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Femoral Stress Fractures: Identification and Management

The following is an article written for the online, video-based physical therapy continuing education company MedBridge

Stress fractures are a common occurrence amongst the military, cross country, and endurance athlete population patient populations. With the prospective studies indicating an incidence of 31% in military personnel and 21% in track and field athletes, this is an area that needs to be thoroughly understood by clinicians working in a direct access environment. While femoral stress fractures only account for 5-7% of all stress fractures, there is currently no validated clinical decision rule in identifying those at risk and therefore other factors need to be considered by the clinician. (Weishaar et al., 2005; Bennell et al., 1996; Milgrom et al., 1985; Matheson et al., 1987; Monteleone et al., 1995; Changstrom et al., 2014)

What causes a femoral stress fractures?

Stress-related bone and soft-tissue injuries occur in response to an excessive progression of repetitive loading activities. These injuries develop when the extent of the micro-damage exceeds the ability of the remodeling process to keep up with the demands placed upon it. With regards to femoral stress fractures, during running, the largest bending moments about the anterior to posterior axes of the proximal femur occurs during the impact phase of loading response. As this occurs, the largest stress is then placed on the medial aspect of the femur (Edwards et al., 2008)

Who is at risk? (Wright et al., 2015; Bennell et al., 1999)

  • Stress fracture injury rates are highest in girls cross country (10.6), girls gymnastics (7.4), and boys cross country (5.4)
  • In endurance athletes, female sex (odds ratio = 2.31) and previous history of stress fracture (OR = 4.99) were found to be significant risk factors
  • The presence of concomitant ipsilateral Femoroacetabular impingement demonstrates a higher incidence in both the general and military population (Goldin et al., 2015; Carey et al., 2013)
  • Recent, sudden increase in training volume, especially in relatively inactive individuals

What is the clinical presentation? (Clement et al., 1993; Weishaar et al., 2005; Wright et al., 2015)

  • Vague pain in the thigh that radiates into the hip and/or groin region
  • Anterior thigh (45.9%), hip (27.0%), and/or groin (8.1%) pain
  • In femoral shaft stress fractures, hip A/PROM not typically limited, but can be painful, however in femoral neck stress fractures, a gross limitation in A/PROM can be present
  • Groin pain with single leg hop (70%)

Special Testing? (Reiman et al., 2012; Reiman et al., 2015)

  • Patellar-pubic Percussion Test
Reliability Sensitivity Specificity +LR -LR
0.89 0.89 – 0.96 0.82 – 0.95 5.1 – 20.4 0.06 – 0.75

 

  • Fulcrum Test
Reliability Sensitivity Specificity +LR -LR
N/A 1.00 1.00 0.00

 

Is conservative management effective?

There have been several case reports and case series detailing successful diagnosis, treatment, and return to sport following conservative management. Unfortunately, at this time, there have been no high level studies supporting the physical therapy intervention in this population. In those case studies detailing successful management, programs included progressive posterolateral hip strengthening, neuromuscular re-education, and a graded return to running/physical activity (Weishaar et al., 2005; Ivkovic et al., 2006; Kang et al., 2005).

Without the clinical decision rules for identification of fracture that are available for the foot/ankle (Ottawa Ankle Rules), knee (Ottawa Knee Rules, Pittsburgh Knee Rules), and cervical spine (Canadian Cervical Spine Rules), evaluation of potential hip fracture needs to be managed with the best available evidence. By taking into consideration patient demographics, subjective report of training volume/progression, and utilizing tests/measures supported in the literature, the treating clinician can more accurately identify those athletes in need of further radiological evaluation.

References:

  1. Reiman et al. Diagnostic accuracy of clinical tests of the hip: a systematic review with meta-analysis. Br J Sports Med. 2012
  2. Reiman MP, Mather RC, Cook CE. Physical examination tests for hip dysfunction and injury. British Journal of Sports Medicine. 2015;49(6):357-361. doi:10.1136/bjsports-2012-091929.
  3. Weishaar M. Identification and Management of 2 Femoral Shaft Stress Injuries. Journal of Orthopaedic & Sports Physical Therapy. 2005;35(10):665-673.
  4. Ivkovic A. Stress fractures of the femoral shaft in athletes: a new treatment algorithm. British Journal of Sports Medicine. 2006;40(6):518-520. doi:10.1136/bjsm.2005.023655.
  5. Kang L. Stress fractures of the femoral shaft in women’s college lacrosse: a report of seven cases and a review of the literature. British Journal of Sports Medicine. 2005;39(12):902-906. doi:10.1136/bjsm.2004.016626.
  6. Wright AA, Taylor JB, Ford KR, Siska L, Smoliga JM. Risk factors associated with lower extremity stress fractures in runners: a systematic review with meta-analysis. British Journal of Sports Medicine. July 2015:bjsports–2015–094828–8. doi:10.1136/bjsports-2015-094828.
  7. Edwards WB, Gillette JC, Thomas JM, Derrick TR. Internal femoral forces and moments during running: Implications for stress fracture development. Clinical Biomechanics. 2008;23(10):1269-1278. doi:10.1016/j.clinbiomech.2008.06.011.
  8. Bennell KL, Matheson G, Meeuwisse W, Brukner P. Risk factors for stress fractures. Sports Med. 1999;28:91-122.
  9. Carey T, Key C, Oliver D, Biega T, Bojescul J. Prevalence of radiographic findings consistent with femoroacetabular impingement in military personnel with femoral neck stress fractures. J Surg Orthop Adv. 2013 Spring; 22(1):54-8.
  10. Goldin M, Anderson CN, Fredericson M, Safran MR, Stevens KJ. Femoral Neck Stress Fractures and Imaging Features of Femoroacetabular Impingement. PM R. 2015 Jun;7(6):584-92. doi: 10.1016/j.pmrj.2014.12.008. Epub 2015 Jan 13.
  11. Weishaar M. Identification and Management of 2 Femoral Shaft Stress Injuries. Journal of Orthopaedic & Sports Physical Therapy. 2005;35(10):665-673.
  12. Bennell KL, Malcolm SA, Thomas SA, et al. Risk factors for stress fractures in track and field athletes. A twelve- month prospective study. Am J Sports Med. 1996;24:810-818.
  13. Milgrom C, Giladi M, Stein M, et al. Stress fractures in military recruits. A prospective study showing an unusu- ally high incidence. J Bone Joint Surg Br. 1985;67:732- 735.
  14. Matheson GO, Clement DB, McKenzie DC, Taunton JE, Lloyd-Smith DR, MacIntyre JG. Stress fractures in athletes. A study of 320 cases. Am J Sports Med. 1987;15:46-58.
  15. Monteleone GP, Jr. Stress fractures in the athlete. Orthop Clin North Am. 1995;26:423-432.
  16. Changstrom BG, Brou L, Khodaee M, Braund C, Comstock RD. Epidemiology of Stress Fracture Injuries Among US High School Athletes, 2005-2006 Through 2012-2013. American Journal of Sports Medicine. 2014;43(1):26-33. doi:10.1177/0363546514562739.

Ice Hockey Injuries: Who gets hurt and why does it matter?

Ice hockey is an inherently physical sport and as such creates situations where injury is possible and often likely. With the influence that injuries can have on a team’s success, research has started to focus on our ability to assess injury risk and prevent injuries before they occur. However, these strategies cannot be effectively laid out until we first understand who gets hurt, when they get hurt, and how they get hurt.

Who gets hurt?

According to a prospective cohort study performed by Flik et al., there is a significant disparity in injury incidence depending upon player position in NCAA Division 1 ice hockey. Only 6.2% of injuries were sustained by goaltenders, whereas 32.7% were defensemen and 61.1% were forwards. In agreement with this distribution, Agel et al found 9.6% of injuries effected goaltenders, 40.8% were defensemen, and 48.3% were forwards. This information also correlated with a recent study investigating injury incidence during the World Championship and Olympic tournaments, where goaltenders were once again the least injured followed by defensemen and forwards. However, when evaluating injuries in the National Hockey League (NHL), the only significant difference found was a higher likelihood of defensemen missing gametime due to injury in comparison to forwards. This study also found that a significant predictor of missing at least 5 games due to injury included being a goaltender (odds ratio = 1.68). So, while goaltenders do not get injured as often, their return to play is often more extended in comparison to other players. These numbers are likely not as drastically position dependent due to the disparity of position players on the ice at one time (3 forwards, 2 defensemen, and 1 goaltender), which may account for a significant amount of the variance reported in the literature at the collegiate, international, and professional levels.

When do they get hurt?

Understanding when injuries occur during the course of an individual game and throughout the course of the season allows us to understand when an athlete is at an increased risk of injury. With regards to the collegiate level, 65.5% of injuries occur during games and 35.5% during practice. Additionally, preseason practice rates were more than twice as high as in season injury rates. Two studies looked into the distribution of injuries during game play and found drastically different results. Agel and colleagues found that most injuries occurred in the 2nd and 3rd periods, which is likely due to athlete fatigue and intensity of gameplay increasing as the game progresses. In contrast to this report, amongst NHL regular season injuries, the vast majority occur in the first period (48.1%). Intuitively, as the NHL season progresses, the likelihood of injury also increases. This increase in injury rate is likely due to player fatigue and increased intensity of play as teams are fighting for a playoff spot.

How do they get hurt?

Due to the physical nature of ice hockey, the vast majority of injuries are contact-related, however non-contact injuries tend to make up a higher proportion of practice injuries. According to Agel and colleagues, non-contact injuries make up 9.7% of injuries during games, whereas they make up 32% of injuries during practice. During games, approximately 50% of injuries are due to contact with another player and 39.6% are due to contact with another object (boards, puck, etc.). In agreement with these trends, in the NHL body checking made up 28.6% of injuries, while incidental contact (14.3%), hit by puck (13.5%), contact with environment (9.4%), and other intentional player contact (7.4%) made up the bulk of injuries incurred. Aside from these mechanisms, non-contact injuries made up 14.8% of all injuries and accounted for 11.7% of man games lost due to injury (1,921 games) between 2009 and 2012. This gives good insight into the general cause of injury, but what types of injury are most common amongst ice hockey players?

Over a 16 season timeframe, injures most often sustained during gameplay included internal derangement of the knee (13.5%), concussion (9.0%), acromioclavicular joint injury (8.9%), upper leg contusion (6.2%), and musculotendinous strain of the hip/groin region (4.5%). However, distribution of injuries during practice shows a slightly different distribution. The most common injuries during practice were musculotendinous strain of the hip/groin region (13.1%), internal derangement of the knee (10.1%), ankle ligament sprain (5.5%), concussion (5.3%), and acromioclavicular joint injury (4.4%). Looking further at this data, during games, the highest prevalence of severe injuries was knee internal derangement and the most common mechanism of injury was due to player contact. Of the most common severe injuries reported, musculotendinous injuries of the pelvis/hip was the only pathology (6.2%) that had a non-contact mechanism as the most common cause. In agreement with these findings, amongst NHL players, the most common sites of injury include the head (17%), thigh (14%), knee (13%), and shoulder (12%). Additionally, with regards to man games lost, these regions also comprised the largest impact on their respective teams. Unfortunately, this study did not break the body regions into specific injuries/pathologies.

Given the fairly vague description of the injuries reported in these large epidemiological studies, it is also important to look more in depth to determine which specific injuries are actually reported in the literature. With regards to knee ligamentous injuries, Sikka and colleagues found that between 2006 and 2010, only 47 players sustained an anterior cruciate ligament tear in the NHL, which is significantly lower than most professional contact team sports. These injuries included 3 goaltenders, 8 defensemen, and 36 forwards. Of these 47 injuries, the reported mechanism for all but one injury was contact with another player and/or with the boards. In addition to the primary ACL rupture, 68% of injuries reported a concomitant meniscal or medical collateral ligament injury as well. Looking at the more commonly injured MCL, from 2003-04 to 2010-11, 13 MCL injuries were reported within one collegiate ice hockey program. This resulted in ten different players being injured (12.7%) and an incident rate of 0.44 per 1,000 athlete exposures. Of these injuries, 77% were contact related and an acute non-contact injury was reported in 15% of cases.

Looking at the most common non-contact injury, hip/pelvic pathology has also been investigated in the literature for this population. Over a four year span, 890 hip or groin injuries were reported in the NHL. Of those reported, 10.6% were found to be intra-articular in nature. There was a very small difference between injury occurring during games (44.6%) and during practice (41.4%), but the vast majority occurred during the regular season (71.2%). The most frequent intra-articular hip diagnosis made in this cohort was hip labral tear (69.1%), followed by hip osteoarthritis (13.8%), hip loose body (6.3%), femoroactebular impingement (5.3%), other hip injury (3.1%), and hip chondromalacia (2.12%). With regards to player position, injuries per 1000 player-game appearances were significantly higher in goaltenders compared with all other players.

Why does it matter?

Having a successful team depends on multiple factors, but regardless of coaching or talent, injuries can have a significant impact on a team’s ability to win. Unfortunately, the NHL does not readily provide injury data to the general public, however ManGamesLost.com has provided data supporting the negative impact of injuries on a team’s success. Over the past five seasons, the Stanley Cup champion has been among the top five least injured teams throughout the regular season. Along those same lines, this season’s President’s Trophy (best regular season record) winning Washington Capitals also had the least man games lost due to injury. Additionally, with the exception of the Pittsburgh Penguins, none of the top five most injured teams have had consistent success over the past five years. In fact, two of those included in the top five most injured also had the two of the worst overall records over this timeframe (Columbus Blue Jackets and Edmonton Oilers).

Screen Shot 2016-04-24 at 3.29.05 PM

In addition to the obvious impact on team performance, when a player returns from a significant injury, their productivity and durability has the potential to decline in the seasons following their return to play. The presence of a meniscal injury was associated with a decreased length of career for all positions. Furthermore, for wings and centers, the number of games played decreased in the first full season after ACL injury from 71.2 to 58.2 and in the second full season to 59.29. With regard to offensive production, there was a 31% reduction in goals scored per season, 60% reduction in assists, and 42% reduction in total points compared with an uninjured control group. Only 37.5% of players who were previously selected as All-Stars were able to regain this honor upon their return to play.

Finally, there is also a financial impact as well. According to Donaldson and colleagues, between the 2009-10 and 2011-12 seasons, 50.9% of NHL players missed at least one game, which translated to a total salary cost of $218 million per year.

With the substantial impact on team performance and the associated financial implications, understanding how to identify those at risk and develop programs to lessen the likelihood of injury are paramount to a successful organization. Part 2 of this series will delve into the evidence regarding injury risk assessment and prevention in this population of athletes.

References:

1. Agel J, Dompier T, Dick R, Marshall S. Descriptive Epidemiology of Collegiate Men’s Ice Hockey Injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 Through 2003–2004. Journal of Athletic Training. 2007;42(2):241-248.

2. Flik K. American Collegiate Men’s Ice Hockey: An Analysis of Injuries. American Journal of Sports Medicine. 2005;33(2):183-187. doi:10.1177/0363546504267349.

3. Currier, Nathan. “The Most Injured NHL Teams Since the 2009-2010 Season.” ManGamesLost.com. N.p., 12 Apr. 2016. Web. 22 Apr. 2016.

4. Donaldson L, Li B, Cusimano MD. Economic burden of time lost due to injury in NHL hockey players. Inj Prev. 2014;20(5):347-349. doi:10.1136/injuryprev-2013-041016.

5. Epstein DM, McHugh M, Yorio M, Neri B. Intra-articular Hip Injuries in National Hockey League Players: A Descriptive Epidemiological Study. American Journal of Sports Medicine. 2013;41(2):343-348. doi:10.1177/0363546512467612.

6. Grant JA, Bedi A, Kurz J, Bancroft R, Miller BS. Incidence and Injury Characteristics of Medial Collateral Ligament Injuries in Male Collegiate Ice Hockey Players. Sports Health. 2013;5(3):270-272. doi:10.1177/1941738112473053.

7. McKay CD, Tufts RJ, Shaffer B, Meeuwisse WH. The epidemiology of professional ice hockey injuries: a prospective report of six NHL seasons. British Journal of Sports Medicine. 2014;48(1):57-62. doi:10.1136/bjsports-2013-092860.

8. Sikka R, Kurtenbach C, Steubs JT, Boyd JL, Nelson BJ. Anterior Cruciate Ligament Injuries in Professional Hockey Players. American Journal of Sports Medicine. 2016;44(2):378-383. doi:10.1177/0363546515616802.

9. Tuominen M, Stuart MJ, Aubry M, Kannus P, Parkkari J. Injuries in men’s international ice hockey: a 7-year study of the International Ice Hockey Federation Adult World Championship Tournaments and Olympic Winter Games. British Journal of Sports Medicine. 2015;49(1):30-36. doi:10.1136/bjsports-2014-093688.

The Importance of Isometrics

An isometric contraction is a static form of exercise in which a muscle contracts to produce force without an appreciable change in muscle length and without visible joint movement1 We learn these basic concepts in school and are told to provide these types of interventions during the early phases of rehabilitation, but do we truly understand the benefit of these seemingly simple exercises?

Eccentrics versus Isometrics

While eccentric exercise is the mainstay of most rehabilitation programs for tendinopathies, some patients find them painful to complete and difficult to perform.2 In these cases, patient compliance suffers due to increased pain, leading to underwhelming outcomes.3

Conversely, the impact of isometric contraction on pressure pain thresholds (PPTs) yields promising results. When asymptomatic volunteers held a quadriceps isometric contraction at 21% MVIC until exhaustion (maximum of 5-minute duration), patients demonstrated a significant increase in PPT at the start of contraction. PPT continued to increase until the middle of the contraction period and stayed increased for up to 5 minutes post-intervention.4

Reduced Perceived Pain

In a similar study, PPTs were determined after 14 healthy women completed 2 sets of submaximal (40-50% MVIC) isometric exercise consisting of squeezing a dynamometer for 2 minutes with their dominant hand.5 This trial demonstrated a positive contralateral and ipsilateral hypoalgesic effect with elevated PPTs and a reduction in self-perceived pain rating for both hands following isometric exercise. While this provides a good foundation of support, it does not provide information regarding isometric exercise’s effect on individuals with a painful condition

To answer this question, Rio and associates performed a randomized cross-over study to investigate the hypoalgesic impact of a single bout of isometric contractions on individuals with patellar tendinopathy.6 Those in the intervention group performed 5 sets of 45 second isometric quadriceps contractions (70% MVIC) with a 2 minute rest break between each set. Those in the control group performed 4 sets of 8 repetitions (100% 8-repition maximum) of an isotonic leg extension exercise with a 4 second eccentric phase and 3 second concentric phase.

At the conclusion of the study, isometric contractions reduced pain during single-leg decline squat from 7.0 to 0.17 on an 11-point scale and increased MVIC by 18%. Both values were maintained for 45 minutes post-intervention. Also, cortical inhibition increased from 27.5% to 54.9%, which may factor into the underlying mechanism of this hypoalgesia.7

Further supporting the hypoalgesic properties of isometric contractions, Rio and colleagues once again added to the depth of literature in this area. They used a within-session randomized controlled trial to compare isometric leg extension at 60 degrees of knee flexion to isotonic leg extension in volleyball or basketball players with patellar tendinopathy. At the conclusion of the study, those randomized to the isometric knee extension group demonstrated significantly greater immediate analgesia throughout the 4 weeks trial.8

Back to the Basics

Isometrics are not simply an introductory exercise for patients following a post-operative procedure (i.e. quad sets following ACL reconstruction). Their hypoalgesic effects are far more impactful then most of us recognize. Although we are not sure why isometrics are efficacious in these tendinopathies, they give us an intervention that is successful.  Clinicians often get too caught up in complex and intricate treatment philosophies when in reality all we have to do is go back to the basics!

References

1. Kisner, Carolyn, and Lynn Allen. Colby. Therapeutic Exercise: Foundations and Techniques. 5th ed. Philadelphia: F.A. Davis, 2007. Print.

2. Alfredson H, Pietila T, Jonsson P, et al. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med 1998;26:360–6.

3. Visnes H, Hoksrud A, Cook J, et al. No effect of eccentric training on jumper’s knee in volleyball players during the competitive season: a randomized clinical trial. Clin J Sport Med 2005;15:227–34.

4. Kosek E, Ekholm J. Modulation of pressure pain thresholds during and following isometric contraction. Pain 1995;61:481–6.

5. Koltyn KF, Umeda M. Contralateral attenuation of pain after short-duration submaximal isometric exercise. J Pain 2007;8:887–92.

6. Rio E, Kidgell D, Purdam C, et al. Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. British Journal of Sports Medicine. 2015;49(19):1277-1283. doi:10.1136/bjsports-2014-094386.

7. Rio E, Kidgell D, Moseley GL, et al. Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review. British Journal of Sports Medicine.2015.

8. Rio E, van Ark M, Docking S, Moseley GL, Dawson K, Gaida J, van den Akker-Scheek I, Zwerver J, Cook J. Isometric Contractions Are More Analgesic Than Isotonic Contractions for Patellar Tendon Pain: An In-Season Randomized Clinical Trial. Clinical Journal of Sport Medicine. 2016.

Hip Pain: Return to Sport Considerations

Pre-arthritic hip pain is a common occurrence among athletes, especially those competing in ice hockey1 and field-based team sports (soccer, rugby, and football).2 While this area receives less attention than knee or shoulder injuries, current research is beginning to improve diagnosis and treatment of both intra-articular and extra-articular hip pathology. But, what about return to sport?

What the Literature Says

Determining an athlete’s readiness to return to sport is complicated. The decision with regards to hip pathology is even more convoluted due to the lack of evidence. Most literature discusses outcomes following arthroscopic surgery, and only a few studies outline the proposed benefit of conservative management.3

The available literature suggests that surgery for femoroacetabular impingement is beneficial in a symptomatic population, with 87% of patients returning to sport and 82% returning to previous level of competition.4 On the other hand, no randomized controlled studies adequately compare conservative and surgical management.5 Unfortunately, at this point the research tends to relate only to reported patient satisfaction, subjective questionnaires, and self-reported return to sport.6

How Do We Determine Return to Sport?

Unlike ACL reconstruction, hip injury lacks sufficient evidence to support return to sport guidelines. According to the 2016 Consensus Statement on Return to Sport, clinicians should combine information from a biological, psychological, and social standpoint.7 These factors include:

  • Health risk based on the athlete’s specific injury (subjective and objective measures)
  • Activity risk of returning to sport (type of sport, competition level, etc.)
  • Risk tolerance (pressure, fear of re-injury, etc.)

The StAART Framework (pictured below) proposed by Shrier and colleagues sums up this approach.8 It allows the clinician to comprehend and address all areas impacted by an individual’s readiness to return to sport.

MC020-205 Starrt Framework Chart_v03

Functional Testing Considerations

A recent systematic review conducted by Kivlan and colleagues demonstrated that several tests are reliable and valid when determining return to sport after hip injuries:9

  • Single-leg Stance
  • Deep Squat
  • Single-leg Squat
  • Star Excursion Balance Test (SEBT) / Y-Balance Test

These tests have appropriate validity and reliability but no solid cut-points, so findings should be interpreted on a patient-specific basis by considering their limb symmetry index during these tasks. Significant increase in medial–lateral sway and worse anterior–posterior control during a dynamic single-leg squat task in individuals with pre-arthric hip pain supports the use of a single-leg squat assessment.10

The modified star excursion balance test (also known as the Lower Quarter Y-Balance Test)  has been successful in identifying asymmetry and impaired proximal stability in many conditions. Recently, Johansson and colleagues performed the first study to determine the criterion and divergent validity of the SEBT in individuals with femoroacetabular impingement11. They determined that SEBT performance in the posterolateral and posteromedial directions had high to moderate criterion validity in relation to the HAGOS subscales for pain intensity and symptoms. Additionally, the posterolateral direction and ADL function showed high to moderate criterion validity. Finally and most importantly, the SEBT showed adequate divergent validity and could successfully differentiate between healthy individuals and individuals diagnosed with FAI.

Several recent studies have investigated if hop testing is appropriate in this population. Kivlan and colleagues evaluated the difference in hop testing (cross-over reach test, medial triple hop test, lateral triple hop test, and cross-over hop test) between the involved and uninvolved hip in dancers with hip pathology.12 All tests demonstrated excellent reliability (0.89 – 0.96); however, only the medial triple hop test showed significant difference between the two limbs with the non-involved limb achieving 17.8 cm more distance than the involved limb.

More recently, Kivlan and colleagues investigated the hop performance between dancers with clinically diagnosed femoroacetabular impingement and an asymptomatic control group. This study found a significant difference of approximately 50 cm when comparing the performance of the FAI group to the asymptomatic control group during both the medial triple hop test and the lateral triple hop test:13

table-remake

Further supporting the use of hop and dynamic balance activities, findings from another recent study determined that following arthroscopic hip surgery and concomitant rehabilitation, patients demonstrated > 90% limb symmetry index in the performance of a single-leg squat test, single-leg vertical jump, single-leg hop for distance, and single-leg side hop.14 While this information shows that we can achieve a LSI that is often used in return to sport of athletes post-ACL reconstruction, functional testing should be used with caution when translating it to a population of athletes with hip pain.

Continue with Caution

In the absence of definitive return to sport criteria, the clinician must focus on the tissue health (the load the tissue can absorb before injury), individual tissue stresses imposed by the athlete’s chosen sport and competition level, and any pertinent psychosocial factors (fear of re-injury).

Return to sport testing should be considered with caution as little evidence is available for this patient population.

References:

1. Lerebours F, Robertson W, Neri B, Schulz B, Youm T, Limpisvasti O. Prevalence of Cam-Type Morphology in Elite Ice Hockey Players. Am J Sports Med. 2016 Jan 28. pii: 0363546515624671. [Epub ahead of print]

2. Gerhardt MB, Romero AA, Silvers HJ, Harris DJ, Watanabe D, Mandelbaum BR. The Prevalence of Radiographic Hip Abnormalities in Elite Soccer Players. American Journal of Sports Medicine. 2012;40(3):584-588. doi:10.1177/0363546511432711.

3. Wall PD, Fernandez M, Griffin D, Foster N. Nonoperative Treatment for Femoroacetabular Impingement: A Systematic Review of the Literature. PMRJ. March 2013:1-9. doi:10.1016/j.pmrj.2013.02.005.

4. Casartelli NC, Leunig M, Maffiuletti NA, Bizzini M. Return to sport after hip surgery for femoroacetabular impingement: a systematic review. British Journal of Sports Medicine. 2015;49(12):819-824. doi:10.1136/bjsports-2014-094414.

5. Reiman MP, Thorborg K, Hölmich P. Femoroacetabular Impingement Surgery Is on the Rise—But What Is the Next Step? Journal of Orthopaedic & Sports Physical Therapy. 2016;46(6):406-408. doi:10.2519/jospt.2016.0605.

6. Sim Y, Horner NS, de SA D, Simunovic N, Karlsson J, Ayeni OR. Reporting of non-hip score outcomes following femoroacetabular impingement surgery: a systematic review. J Hip Preserv Surg. 2015;2(3):224-241. doi:10.1093/jhps/hnv048.

7. Ardern CL, Glasgow P, Schneiders A, et al. 2016 Consensus statement on return to sport from the First World Congress in Sports Physical Therapy, Bern. British Journal of Sports Medicine. May 2016. doi:10.1136/bjsports-2016-096278.

8. Shrier I. Strategic Assessment of Risk and Risk Tolerance (StARRT) framework for return-to-play decision-making. British Journal of Sports Medicine. 2015; 49: 1311–15.

9. Kivlan BR, Martin RL. Functional Performance Testing of the Hip in Athletes: A Systematic Review for Reliability and Validity. International Journal of Sports Physical Therapy. 2012;7(4):402-412.

10. Freke MD, Kemp J, svege I, Risberg MA, Semciw A, Crossley KM. Physical impairments in symptomatic femoroacetabular impingement: a systematic review of the evidence. British Journal of Sports Medicine. June 2016. doi:10.1136/bjsports-2016-096152.

11. Johnansson AC, et al. The Star Excursion Balance Test: Criterion and divergent validity on patients with femoral acetabular impingement. Manual Therapy. 2016; 26(C): 104-109. doi:10.1016/j.math.2016.07.015.

12. Kivlan BR, Carcia CR, Clemente FR, Phelps AL, Martin RL. Reliability and validity of functional performance tests in dancers with hip dysfunction. International Journal of Sports Physical Therapy. 2013 Aug;8(4):360-9.

13. Kivlan BR, et al. Comparison of Range of Motion, Strength, and Hop Test Performance of dancers with and without a Clinical Diagnosis of Femoroacetabular Impingement. International Journal of Sports Physical Therapy. 2016; 11(4): 527-535.

14. Tijssen M, van Cingel R, de Visser E, Sanden der MN-V. A clinical observational study on patient-reported outcomes, hip functional performance and return to sports activities in hip arthroscopy patients. Physical Therapy in Sport. 2016;20(C):45-55. doi:10.1016/j.ptsp.2015.12.004.

Evidence-Based Strength Training: Gluteus Maximus

To build upon my previous post regarding Evidence-based Strength Training of the Gluteus Medius, I wrote the following article for MedBridge Education

Pain and Gluteal Strength

The gluteal musculature has been implicated in many different pathologies due to its potential impact on lower extremity biomechanics. During weight bearing, the femur moves about a fixed patella and therefore excessive femoral internal rotation and adduction results in increased contact directed primarily at the lateral facet of the patella1. Just 10° of IR can lead to a substantial decrease in PFJ contract area and a 50% increase in joint stress. Coinciding with these findings, Souza et al.2 found that females with patellofemoral pain syndrome (PFPS) demonstrated greater peak hip internal rotation compared to the control group during running, drop jump, and step down. The PFPS group also demonstrated 14% weaker hip abductor strength and 17% weaker hip extensor strength. Wilson et al3, Noehren et al4, and Nakagawa et al5 found that individuals presenting with PFPS demonstrated increased hip adduction during running, jumping, and single-leg squats. This excess femoral adduction creates an increased valgus force about the knee joint, which in turn causes increased loading of the lateral patellofemoral joint. In addition to patellofemoral pain, a hip etiology or influence has also been implicated in iliotibial band syndrome6, anterior cruciate ligament rupture7, and achilles tendinopathy8. More specifically, impaired gluteus maximus function has been demonstrated in individuals diagnosed with femoroacetabular impingement9.

Gluteal strengthening and Rehabilitation

In support of a gluteal etiology, several studies have found the effectiveness of gluteal strengthening in the treatment of lower extremity disorders. A recent systematic review conducted by Santos and colleagues9 found gluteal strengthening decreased the highest intensity of pain experienced during the previous week, pain when ascending and descending stairs, and pain while squatting or sitting for prolonged periods amongst individuals diagnosed with PFPS. Additionally, with regards to rehabilitation following anterior cruciate ligament reconstruction, the inclusion of hip strengthening appears to improve sagittal plane dynamic balance at three months post ACLR as compared to traditional rehabilitation10.

EMG Activity and Exercise Goals

According to Reiman et al.11 and Escamilla et al.12, moderate electromyographic activity (EMG) activation (21-40% MVIC) is best used to facilitate endurance and neuromuscular re-education; high activation (41-60+% MVIC) in order to promote strength gains.

From Biomechanics to Exercises

Gluteus Maximus

Origin: Ilium posterior to posterior gluteal line; dorsal surface of sacrum and coccyx; sacrotuberous ligament

Insertion: Iliotibial tract and gluteal tuberosity

Primary Function: Extends thigh and assists in hip abduction and external rotation; steadies thigh and assists in rising from sitting position

Among introductory exercises, the gluteus maximus achieves the highest EMG levels during:

  1. Front-plank with Hip Extension
  2. Gluteal Squeeze
  3. Side-plank with Hip Abduction
  4. Quadruped with Contralateral Arm/Leg Lift
  5. Uni-lateral Bridge

screen-shot-2016-09-19-at-2-51-18-pm

Additionally, you must consider the interaction of other muscles acting with or against the gluteus maximus when determining exercise prescription. It has been proposed that individuals who demonstrate excess femoral internal rotation during functional tasks may be relying too heavily on the tensor fasciae latae to control their pelvis in the presence of weak or inhibited gluteus medius musculature.

Selkowitz and colleagues determined that the following exercises achieved the best Gluteal to Tensor Fasciae Latae Activation Ratio:

  1. Clamshell
  2. Side-step with resistance band
  3. Single-leg bridge
  4. Quadruped hip extension with knee extended
  5. Quadruped hip extension with knee flexed

screen-shot-2016-09-19-at-2-55-12-pm

Finally, when progressing your patient towards more functional closed kinetic chain and sport/activity-specific exercises, the following exercises achieve the highest gluteus medius activation:

  1. Cross-over Step-up
  2. Hip Thrust Variations (Barbell, Band, American)
  3. Rotational Single-Leg Squat
  4. Skater Squat
  5. Single-Leg Squat

screen-shot-2016-09-19-at-2-56-43-pm

Exercise prescription is a multi-faceted decision, which is driven by the individual patient’s goals, functional limitations, and the evidence supporting the treatment of these factors. Using EMG studies to drive the selection of exercise is highly valuable, especially during early stages of rehabilitation or when attempting to isolate individual muscles and/or groups of muscles. However, there are limitations when comparing different studies due to methodological differences (type of EMG, patient population, data analysis, etc.). Additionally, due to the cost and time to conduct these studies, there are thousands of exercises that have not been evaluated in the literature. In light of this information, these studies should be used to guide your decision making, it should not override your clinical expertise when accompanied by biological plausibility.

Learn from John: Upcoming Courses

I will be teaching two one-day continuing education courses in Indiana later this month through Medical Minds in Motion. These courses will teach clinicians (PT, PTA, or OT) evidence-based assessment, treatment, and return to sport/recreation of hip pathology.

For more information, see the below links for specific details of each course or feel free to message me directly.

February 27th – Indianapolis, Indiana – Evidence-Based Assessment and Treatment of the Hip Joint

February 28th – Evansville, Indiana – Evidence-Based Assessment and Treatment of the Hip Joint

Thanks!

John Snyder, PT, DPT, CSCS

Conservative Management of Femoroacetabular Impingement

The following is an article written for the online, video-based physical therapy continuing education company MedBridge

FAI Prevalence

As mentioned in my previous post on differential diagnosis of femoroacetabular impingement (FAI), hip pain is an all too common occurrence among older adults and adolescents.1

    • Older adults. According to a survey and subsequent study of 2,221 German respondents (predominantly female and > 40 years old), 15.2% reported hip pain and 3.5% reported bilateral hip pain.2
    • Adolescents. Spahn et al found that 6.5% of German adolescents reported hip pain. Women were more likely to be affected, along with individuals that consumed alcoholic beverages.3

A multitude of different pathologies and medical conditions explain the hip pain, but the more common cause is FAI. Young, active individuals with hip pain generally have very high incidence of FAI (as high as 87%).4

Is Conservative Care Effective for FAI?

With such a high prevalence, especially in athletes, clinicians must understand the evidence for conservative management.

To determine the effectiveness of therapy and other conservative care, Wall and colleagues conducted a systematic review of the available literature.5 Unfortunately, only 5 studies met the inclusion criteria due to the significant predominance of surgical interventions versus conservative care.

Benefits of Exercise and Activity Modification

That said, two studies with high-quality evidence found that patients can benefit from physical therapy and activity modification. The physical therapy programs included exercise-based staged rehabilitation focusing on the core hip musculature, education, and advice to help reduce the frequency of impingement.

In the first study, only 4 of 37 patients ended up undergoing surgical intervention.6 The remaining 33 subjects significantly improved their mean Harris Hip Score from 72 to 91 points at the 24-month follow-up.

The second study found no significant differences in pain and function when comparing conservative care to conservative care plus surgical intervention.7 Both groups showed improvement at the one-year follow-up.

Separately from this systematic review, a case report also found promising results for prescribing an augmented home exercise program of standing lateral glides and supine inferior glides of the hip using a belt.8

Interventions

Going back to the systematic review, the successful conservative FAI management programs included the following interventions.

  • An overwhelming emphasis was put on core and gluteal musculature training.
  • Most programs focused on pain-free stretching of the hip flexor muscle group.
  • PROM and stretching at end-ranges of hip flexion and internal rotation were avoided.

Interestingly, only one of the programs included joint mobilization or specific manual therapy interventions. Based on the evidence supporting manual therapy in other hip pathologies, and the general FAI pathomechanics, it would appear that joint mobilization techniques should significantly enhance FAI rehabilitation.9

However, more recently Wright and colleagues investigated the effectiveness of conservative management in the treatment of FAI with favorable results10. In this small pilot study, patients were randomly assigned to receive either manual therapy and supervised exercise or advise and a home exercise program. At the conclusion of the 6 week treatment period, there was not a significant difference between the two groups, however both groups showed significant improvements in pain.

Conservative management of FAI is horribly underrepresented in the literature, but the scarce evidence available does provide some optimism. With the lack of definitive evidence supporting specific interventions, therapists must rely on the remaining two pillars of evidence-based practice: experience and patient beliefs.

Evolution of the Treatment-Based Classification for Low Back Pain

The following is an article written for the online, video-based physical therapy continuing education company MedBridge

The prevalence and economic burden of low back pain (LBP) has reached an epidemic level and continues to put a strain on the U.S. healthcare system. According to Hoy et al, the overall incidence of LBP is between 1.5% and 36% with incidence of first-ever LBP ranging between 6.3-15.3%.

This is a HUGE proportion of the general population and typically makes up a large portion of the therapist’s daily caseload. Through the improvement of medical imaging, physicians are better able to see “what’s going on” inside an individual’s spine, but is this information helpful?

Is Medical Imaging the Answer?

The accuracy of the pathoanatomical model in diagnosing and treating LBP is severely overrated. Multiple imaging studies have proven this model is limited by the high rate of false-positives. For example, a study conducted by Savage et al found that 32% of asymptomatic individuals had ‘abnormal’ lumbar spines (as determined by MRI) and 47% of symptomatic individuals had no evidence of abnormality. Additionally, Jarvik and colleagues found no benefit with regards to patient self perceived disability when imaging was conducted early in their course of care. So, if medical imaging isn’t the answer, then how do we diagnose and treat these patients?

Treatment-Based Classification and Its Evolution

According to the Low Back Pain Clinical Guidelines published by Delitto et al, “The best available evidence supports a classification approach that de-emphasizes the importance of identifying specific anatomical lesions after red flag screening is completed.” Within the physical therapy community, there are several unique classification systems, but only one is backed by a substantial bounty of evidence. This Treatment-Based classification (TBC) system distinguishes 4 sub-groups of patients that are treated with specific interventions depending upon their classification. These sub-groups include:

This system was initially proposed by Delitto et al in 1995 and has evolved over the greater part of two decades. Below is a table created by Fritz et al presenting both both the original criteria and the revision proposed in 2007.

FritzTBC2007

Recently, the TBC approach to the management of low back pain underwent another revision in order to address several limitations that have come to light since its revision in 2007. Alrwaily et al recognized that the current system was lacking in addressing the biopsychosocial aspects of low back pain and that the categorization process was not efficient enough. In order to improve this system, the following areas were updated:
  1. Initial triage process includes all healthcare providers who come in first contact with patients with LBP in addition to the level of the rehabilitation provider
  2. Establishing decision-making criteria for the first contact practitioner to triage patients into one of three approaches: medical management, rehabilitation management, self-care management
  3. Utilizing risk stratification and psychosocial tools to determine which patients require psychologically informed rehabilitation
  4. The treatment based classification categories were broadened in order to prevent misclassification of patients

One of the largest issues with the 2007 TBC system proposed by Fritz et al was an inability to match patients to their appropriate treatment group. An evaluation by Stanton et al in 2011 determined that when a patient did not match a specific intervention, they were broadly lumped into the stabilization category or simply remained unclassified. In addition to this flaw, another study conducted by Stanton and colleagues found that close to 25% of patients met the criteria for at least two of the included treatment categories.

In order to address these limitations, Alrwaily and colleagues once again revised the classification system in 2015. This new system breaks the initial triage process into the level of the first healthcare provider contact (direct access) and rehabilitation provider. At the level of the first provider, the patient is directed either toward medical management, rehabilitation management, or self management. This determination is based on the presence/absence of red flags and neurological deficits. Once the patient has been transitioned to rehabilitation management, the classification categories have been broadened in order to direct patients toward the correct treatment approaches. Instead of breaking the categories into specific interventions, they are now broken into logical groups of interventions (symptoms modulation, movement control, and functional optimization). This alteration will prevent patients from being categorized into multiple groups or not being classified what so ever.

TBC2015

Treatment-Based Classification Yields Better Outcomes

In 2000, Fritz et al published a prospective cohort study looking at short-term patient outcomes after matching patient sub-groups to their corresponding treatment strategies. This study evaluated the outcomes of 120 patients receiving physical therapy for acute LBP. While Fritz’s initial evaluation of this treatment strategy did not compare its effects to standard care, it did give some preliminary support to its efficacy.

Later in 2003, Fritz et al conducted a randomized controlled trial of 78 patients comparing their treatment-based classification system to the current clinical guidelines for patients with acute LBP. Patients with work-related LBP of less than 3 weeks duration were admitted after being cleared of “red flags.”

Guideline Group

Subjects assigned to the Guideline Group (GG) were treated with low-stress aerobic exercise (treadmill walking or stationary cycling), general muscle reconditioning exercises, and advice was given to remain as active as possible within the limits of their pain.

Classification Group

Patients in the Classification Group (CG) were evaluated and assigned to the most appropriate sub-group. Following assignment, they were then treated based on the system proposed by Delitto et al.

Results

At 4 weeks, when compared to the GG, the CG had statistically significant mean improvements within group in:

  • Oswestry (22.5 v. 11.6),
  • SF-36 PCS (-13.6 v. -8.0)
  • Improved median satisfaction with treatment

At the one-year follow-up, mean Oswestry scores approached, but did not meet statistical significance (p= 0.063) in favor of the CG.

In terms of healthcare utilization, of the 20 patients who took up 51% of the total medical costs, 13 were from the GG and only 7 were from the CG. This translated into a relative risk of 2.1 for the guideline group and a number needed to treat of 5.5, or an average number of patients who need to be treated to avoid a ‘high cost’ patient when using the classification system compared to the clinical guideline approach.

Why It Works: Superior Interventions or the Matching Principle?

What if the interventions being provided from the previous clinical guideline standards were simply inferior to the techniques used by the classification group? Would proper pairing of presentation to treatment remain an important factor in outcomes when the same interventions were used throughout the patient population?

Brennan et al published a randomized controlled trial that investigated the impact of pairing interventions to the correct sub-group of patients with non-specific LBP. In evaluation of 123 patients, those individuals who were matched to the correct treatment approach demonstrated greater short- and long-term improvements in disability compared to those who were unmatched. Patients in the matched group achieved significantly greater improvements in mean Oswestry scores at 4 weeks (29.9 v. 23.3) and one year from baseline (33.3 v. 26.1).

Additionally, 78% of subjects in the matched group achieved progression to stage II of treatment, while only 60% of the unmatched patients achieved this milestone (p= 0.039). This study gave continued credence to the application of a treatment-based approach in the management of acute LBP.

Do the Outcomes Depend on a Clinician’s Experience?

The above studies give the treatment-based classification system solid evidence-based support, but is it reliable enough for widespread utilization by clinicians?

Fritz et al evaluated the inter-rater reliability of individual examination characteristics related to the treatment-based classification system in clinicians with varying levels of experience.

The evaluation included:

  • 10 ‘novice’ physical therapists (< 5 years of experience, no experience using the classification system)
  • 10 ‘experienced’ physical therapists (5+ years of experience, no experience using the system)
  • 10 ‘expert’ physical therapists (used the system clinically and participated in research involving the system)

Patients were evenly distributed to each clinician category with between 24-25 patients seen by each group. In terms of individual examination characteristics, the inter-rater reliability coefficients were at least moderate for all range of motion measurements, the prone instability test, and judgments of centralization/peripheralization with flexion and extension ROM. However, reliability of centralization/peripheralization with repeated or sustained extension movements and judgments of aberrant movements were fair or poor.

The ultimate agreement among clinicians on patient placement within the classification decision-making algorithm was 75.9%, which correlated to a kappa value of 0.60 (moderate agreement). Additionally, there was no significant difference in kappa value depending on experience of the examining therapist.

Earlier this year, Henry et al conducted a similar study with 12 therapists evaluating 24 total patients. This small cross-sectional reliability study produced total agreement on classification of 80.9% and a kappa value of 0.62 (moderate-good agreement), which agrees with the previous study by Fritz et al.

The Most Effective Evidence-Based Tool for Low Back Pain

This classification system has been rigorously evaluated and has come out with moderate to good inter-rater reliability regardless of clinician experience or expertise. This goes along with the improved clinical outcomes and decreased healthcare costs seen in two large randomized controlled trials. Currently, this is the most consistent and effective evidence-based tool to evaluate and treat LBP and should be considered a viable option for any therapist.

Additionally, as new evidence comes to light, the system continues to evolve in order to accommodate the growing body of evidence with regards to the evaluation and treatment of low back pain. During clinical practice, not every patient will fit nicely into a specific subgroup, but having this framework aids clinicians in making more informed, evidence-based treatment decisions.

VMO: An Update

The following is an article written for the online, video-based physical therapy continuing education company MedBridge

Patellofemoral pain syndrome (PFPS) is among the most common sports injuries and yet the current treatment protocols are not optimal. In particular, the latest research questions our ability to selectively recruit vastus medialis obliquus (VMO) and affect its timing and suggests that VMO may have nothing to do with the PFPS.

Prevalence of Patellofemoral Pain Syndrome

PFPS has an astounding prevalence according to a retrospective case-control analysis by Taunton et al. They analyzed 2,002 running-related injuries seen at a primary care sports injury facility – and 42.1% (842/2,002) were knee injuries. Of these knee injuries, 39.3% (331/842) were due to patellofemoral pain syndrome (PFPS), which made PFPS by far the most common diagnosis found in this large-scale study.

Similarly, in an older study (1984), Devereaux et al found that over a five year period, 137 patients presented with PFPS – accounting for 25% of all knee injuries seen at this sports injury clinic.

These two studies were conducted 17 years apart, giving support to the consistently high prevalence of this disorder. Now the most important question is, how are we treating these patients?

How are we treating patients with PFPS?

Imbalance of LV and VMO

The biomechanical study by Lieb et al made the VMO the mainstay of most physical therapy protocols and treatment approaches for PFPS.

Conducted in 1968, the study found that VMO’s fibers are oriented at 55° from the longitudinal axis of the femur. This orientation alone makes VMO the primary restraint to lateral subluxation of the patella. The study further postulated that VMO was able to counterballance the pull of the much larger vastus lateralis (VL) due to the discrepancy in mechanical advantages.

As a result of this study, an insufficient balance between the VL and VMO has long been considered the primary contributing factor in developing patellar subluxation, or maltracking.

VL:VMO timing

A study by Cowan et al found that subjects with PFPS have an imbalance of VL:VMO timing. The VL typically begins to fire approximately 15-20 ms prior to the VMO.

Due to this understanding of the biomechanics, the treatment strategy typically involved correcting the potential VMO atrophy, hypoplasia, inhibition, and impaired motor control.

Now, this all seems logical in theory, but can we actually selectively train the VMO? Is this relatively small muscle affected differently than the rest of the quadriceps musculature in the presence of pain?

New research questions…

Does VMO atrophy relative to the rest of quadriceps?

A recent study by Giles and colleagues refutes one of the cornerstones of the VMO theory; namely, that this small muscle tends to atrophy relative to the rest of the quadriceps during or following surgery. They performed a cross-sectional study of 35 participants diagnosed with PFPS.

The results showed atrophy of all portions of the quadriceps muscles – and no selective atrophy of the VMO – present in the affected limb of people with unilateral PFPS.

Can we selectively activate VMO?

Even if the atrophy was present, the literature is not very kind to the ability to preferentially activate this musculature either.

Cerny et al evaluated the ability to preferentially recruit the VMO during 22 different quadriceps exercises. Through electromyographic analysis, they determined that VMO activity was not higher in any exercise compared to VL.

In a randomized controlled trial, Song et al found no evidence that VMO can be activated separately. They compared the change in VMO cross-sectional area after 8 weeks of unilateral leg press and unilateral leg press with subsequent hip adduction. The two groups showed no significant difference between the change in VMO cross-sectional area (the standard leg press actually yielded better results).

Thus, selective isolation of the VMO in everyday clinical practice is highly unlikely. In all reality, if we consider inability to selectively recruit their target, most of the ‘VMO programs’ are merely strengthening the quadripceps as a whole. If we could selectively recruit these fibers, according to Grabiner et al, it would take approximately 60% of maximal voluntary contraction to stimulate hypertrophy of the VMO.

Does VMO training have advantages over general quadriceps strengthening?

In 2010, Bennell et al investigated how VMO retraining compares to a general quadriceps strengthening program in relation to vasti onset.

The VMO retraining group used EMG biofeedback during the following series of exercises:

  • isometric VMO contractions at 90° of knee flexion
  • standing mini squats to 40°
  • isometric contraction of the VMO in combination with hip abduction and hip external rotation during an isometric wall contraction in standing
  • step downs

The quadriceps group performed:

  • isometric quad sets
  • straight-leg raises
  • SAQs
  • side-lying hip abduction

At the conclusion of the training programs, the retraining group actually did create more significant changes in stair descent activation in the short-term. However, at the 8-week follow-up, both values were nearly identical. The initial improvement may have been due to the use of ‘step downs’ in the retraining group, which most closely simulates the functional and muscular demands of stair descent.

During stair ascent, on the other hand, the quadriceps strengthening group caused a much more significant alteration in VMO:VL timing and was the only group that caused the VMO to fire prior to the VL.

A study conducted by Laprade et al showed similar results using isometric exercise. This study compared the EMG activity in individuals with PFPS and asymptomatic controls during 5 isometric exercises. There was no significant difference in the ratio of VMO:VL firing between the two groups.

Given these results, I find it hard to support the use of VMO training in everyday clinical practice.

Does VMO strengthening make a difference for PFPS?

Suppose it was possible to selectively recruit the VMO. Would it reduce patellofemoral contact stress sufficiently to relieve the pain?

Sawatsky et al say no. They conducted a biomechanical study using New Zealand white rabbits. Although this is not a direct human study, the muscular alignment and pull of the quadriceps is very similar: the fibers of the VMO and VL are oriented at 45-50° and 14-19°, respectively, in relation to the longitudinal axis of the femur.

They transected VMO at varying levels of knee flexion (30°, 60°, and 90°), measuring patellofemoral joint contact pressures before and after the transections.

There were no significant differences between peak pressures, average pressures, contact areas, or contact shapes before and after transection.

If the contact area and pressure are not altered when the muscle is removed from the equation, then why do we continue thinking VMO training is the gold standard in PFPS treatment?

Evidence-Based Strength Training: Gluteus Medius, An Update

To build upon my previous post regarding Evidence-based Strength Training of the Gluteus Medius, I wrote the following article for MedBridge Education

Pain and Gluteal Strength

The gluteal musculature has been implicated in many different pathologies due to its potential impact on lower extremity biomechanics. During weight bearing, the femur moves about a fixed patella and therefore excessive femoral internal rotation and adduction results in increased contact directed primarily at the lateral facet of the patella1. Just 10° of IR can lead to a substantial decrease in PFJ contract area and a 50% increase in joint stress. Coinciding with these findings, Souza et al.2 found that females with patellofemoral pain syndrome (PFPS) demonstrated greater peak hip internal rotation compared to the control group during running, drop jump, and step down. The PFPS group also demonstrated 14% weaker hip abductor strength and 17% weaker hip extensor strength. Wilson et al3, Noehren et al4, and Nakagawa et al5 found that individuals presenting with PFPS demonstrated increased hip adduction during running, jumping, and single-leg squats. This excess femoral adduction creates an increased valgus force about the knee joint, which in turn causes increased loading of the lateral patellofemoral joint. In addition to patellofemoral pain, a hip etiology or influence has also been implicated in iliotibial band syndrome6, anterior cruciate ligament rupture7, and achilles tendinopathy8.

Gluteal strengthening and Rehabilitation

In support of a gluteal etiology, several studies have found the effectiveness of gluteal strengthening in the treatment of lower extremity disorders. A recent systematic review conducted by Santos and colleagues9 found gluteal strengthening decreased the highest intensity of pain experienced during the previous week, pain when ascending and descending stairs, and pain while squatting or sitting for prolonged periods amongst individuals diagnosed with PFPS. Additionally, with regards to rehabilitation following anterior cruciate ligament reconstruction, the inclusion of hip strengthening appears to improve sagittal plane dynamic balance at three months post ACLR as compared to traditional rehabilitation10.

EMG Activity and Exercise Goals

According to Reiman et al.11 and Escamilla et al.12, moderate electromyographic activity (EMG) activation (21-40% MVIC) is best used to facilitate endurance and neuromuscular re-education; high activation (41-60+% MVIC) in order to promote strength gains.

From Biomechanics to Exercises

Gluteus Medius

Origin: External surface of Ilium between anterior and posterior gluteal lines

Insertion: Lateral surface of greater trochanter

Primary Function: Abduction of the hip joint; the anterior fibers contribute to hip flexion and hip internal rotation, and the posterior fibers to hip extension and hip external rotation. Additionally, the gluteus medius is responsible for preventing the opposite side of the pelvis from dropping during the stance phase of gait and plays a major role in providing frontal stability for the entire pelvis during walking and other functional activities.

The gluteus medius achieves the highest EMG levels during13,14:

  1. Side-lying plank with hip abduction
  2. Reverse clamshell with hip abduction and extension
  3. Prone plank with hip extension
  4. Reverse clamshell with hip abduction
  5. Single-leg Bridge

Screen Shot 2015-07-26 at 3.30.35 PM

Additionally, you must consider the interaction of other muscles acting with or against the gluteus medius when determining exercise prescription. It has been proposed that individuals who demonstrate excess femoral internal rotation during functional tasks may be relying too heavily on the tensor fasciae latae to control their pelvis in the presence of weak or inhibited gluteus medius musculature.

Selkowitz and colleagues determined that the following exercises achieved the best Gluteal to Tensor Fasciae Latae Activation Ratio15:

  1. Clamshell
  2. Side-step with resistance band
  3. Single-leg bridge
  4. Quadruped hip extension with knee extended
  5. Quadruped hip extension with knee flexed

Screen Shot 2015-07-26 at 3.23.48 PM

Finally, when progressing your patient towards more functional closed kinetic chain and sport/activity-specific exercises, the following exercises achieve the highest gluteus medius activation13,16,17,18:

  1. Walking lunge with dumbbell in contralateral hand
  2. Unilateral mini-squat
  3. Skater squat
  4. Unilateral deadlift
  5. Unilateral wall squat

Screen Shot 2015-07-26 at 3.24.37 PM

Exercise prescription is a multi-faceted decision, which is driven by the individual patient’s goals, functional limitations, and the evidence supporting the treatment of these factors. Using EMG studies to drive the selection of exercise is highly valuable, especially during early stages of rehabilitation or when attempting to isolate individual muscles and/or groups of muscles. However, there are limitations when comparing different studies due to methodological differences (type of EMG, patient population, data analysis, etc.). Additionally, due to the cost and time to conduct these studies, there are thousands of exercises that have not been evaluated in the literature. In light of this information, these studies should be used to guide your decision making, it should not override your clinical expertise when accompanied by biological plausibility.