Things are not always as they seem… The Basis for a Regional Interdependence Model

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

Think for a minute about what you would do if the following patient walked into your clinic…

A 24-year-old female patient presents with left anterior knee pain, which was exacerbated after beginning a rigorous marathon training program. No other complaints other than pain during her runs and for 4-6 hours thereafter, but no other functional limitations when performing her ADLs. 

So, based on this scenario, where would you focus your evaluation? My guess is that the majority of clinicians would focus on the knee and more specifically, the patellofemoral joint. Active and passive range of motion would be taken, gross lower extremity strength would be screened, and special tests would be performed. But, what if the patellofemoral joint was not the issue?

While these tests and measures are often indicated, with regards to musculoskeletal injuries, a joint or muscle group proximal or distal to the involved site can actually be the cause of the patient’s complaints. This concept is known as Regional Interdependence. This can be seen with a variety of orthopedic complaints as hip involvement has been associated with low back pain (Cibulka et al) and knee osteoarthritis (Cliborne et al), and thoracic/rib involvement in neck pain (Cleland et al) and subacromial impingement (Bergman et al). Specifically speaking of patellofemoral pain syndrome (PFPS) and our marathon running patient, proximal and distal impairments have also been shown to be very common in this patient population. A recent study conducted by Khayambashi et al found that following 8 weeks of hip abductor and external rotator strengthening, reduced pain and improved function was reported in women with PFPS in comparison to a control group. Furthermore, Khayambashi et al later conducted a randomized controlled trial comparing quadriceps strengthening to posterolateral hip strengthening in patients with PFPS. This study once again favored the hip-strengthening group with improvements in VAS and WOMAC scores in the posterolateral hip exercise group being superior to those in the quadriceps exercise group post-intervention and at 6-month follow-up. Going along with these findings, a systematic review investigating the utility of proximal stability training in patients with PFPS, which included 8 RCTs and found a consistent reduction of pain and improved function in the treatment of patellofemoral pain (Peters et al). Additionally, looking distally from the knee at the foot/ankle joint, according to a case-control study performed by Barton et al, individuals who present with PFPS, possess a more pronated foot posture and increased foot mobility compared to controls.

So, as the research shows, there is a fairly significant amount of evidence supporting the premise of Regional Interdependence, but how do we evaluate how and where to address the potential proximal or distal impairments? While there are several systems available to therapists to identify and address impairments based on the regional interdependence model, one of the most well-known and widely accepted systems is that of the Selective Functional Movement Assessment (SFMA). This system consists of a series of 7 full-body movement tests designed to assess fundamental patterns of movement, such as bending and squatting, in those with known musculoskeletal pain. From this assessment, interventions can then be applied to the identified impairments. While in comparison to its brother system, the Functional Movement Screen (FMS), which was developed for movement assessment in individuals without a painful condition, the SFMA has significantly less research available. That being said, a reliability study was recently conducted by Glaws et al in the International Journal of Sports Physical Therapy. This study found intra-rater reliability that ranged from Good to Poor and inter-rater reliability ranging from slight to substantial agreement. Those raters with increased experience utilizing the system demonstrated superior performance compared to those who were less experienced. This study provides preliminary evidence with regards to the reliability of the system, but there has yet to be a study conducted to validate the system’s effectiveness. In lieu of this evidence, the system itself still provides a reliable way to assess your patient’s movement impairments and allows the clinician to apply interventions, whether manual therapy techniques or therapeutic exercise, that will improve the patient’s quality of movement. For further information regarding the SFMA and its utility, take the time to understand the intricacies of the system by taking “Movement Dysfunction: An Evidence-Based Overview” by Kyle Kiesel, PT, PhD, ATC. The research indicates that movement relies on a coordinated interaction of multiple joints, muscles, and biological systems (cardiovascular, musculoskeletal, neurological, ect.). Because of these multiple influences, the therapist must look at potential factors that may be predisposing the patient to their painful condition and many times this will take us away from the effected joint.

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