Effectiveness of Manual Therapy for Knee Pain

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

Knee osteoarthritis (Knee OA) is one of the most prevalent and debilitating orthopedic complaints for 28% of adults over 45 years old and 37% of those over 65 years old in the United States. In addition, 1.6% of adults over the age of 60 have undergone total knee arthroplasty (Dillon et al). Improving the underlying mobility, strength, pain, and functional limitations associated with this pathology is a critical component of patient care. There are a number of interventions employed by physical therapists for individuals suffering from knee pain – some more effective than others. Amongst one of the more common, albeit controversial, is the use of manual therapy, or more specifically, joint mobilization.

In 2000, Deyle et al published an initial investigation into the potential effectiveness of manual therapy techniques in combination with exercise in the treatment of knee OA. In this randomized controlled trial, patients in the intervention group received manual therapy techniques based on their specific impairments, which potentially included passive physiologic and accessory joint movements, muscle stretching, and soft-tissue mobilization, applied primarily to the knee. However, if any additional deficits were found in other regions (i.e. hip, foot/ankle, lumbar spine), manual therapy techniques were directed at these areas. At the completion of the study, the intervention group achieved significant improvements in 6-minute walk distance and WOMAC score at 4 weeks and 8 weeks. Additionally, only 5% of those in the intervention group underwent total knee arthroplasty (TKA) in comparison to 20% in the control group. This study was a great first step, however as the control group only received subtherapeutic ultrasound for 10 minutes to the area of knee symptoms, further investigation was warranted.

Later in 2005, Deyle et al conducted a similar study with a control group, which included a standardized home exercise program. In this study, patients in the intervention group received 8 sessions of manual therapy treatment, which consisted of passive physiological and accessory movements, manual muscle stretching, and soft-tissue mobilization. These techniques were primarily applied to structures in the knee region opposed to the holistic approach previously used in the 2000 study. At the 4 week follow-up, WOMAC scores had improved by 52% in the clinic treatment group compared to 26% in the home exercise group, whereas both groups improved by approximately 10% in their 6-minute walk distances. Additionally, at the one-year follow-up, there was no significant difference between groups in either measure. This study gives credence to short-term functional improvements for manual therapy techniques, but not necessarily walking speed or capacity. While this does offer some evidence to support the inclusion of manual therapy, it also puts into question whether a home exercise program is an adequate comparison group.

More recently, Abbott et al conducted a randomized controlled trial comparing manual therapy, exercise, and combined manual therapy and exercise, and a usual care group in the treatment of hip and knee OA. The findings of this study were interesting, at the one year follow-up, both the manual therapy and exercise groups achieved statistically significant improvements with regards to reduction in WOMAC scores. Whereas, combined manual therapy and exercise did not meet this same significant improvement. Along with these findings, following the intention to treat analysis, all intervention groups improved but only usual care plus manual therapy and usual care plus exercise therapy achieved clinically significant reductions of >28 WOMAC points from baseline. Once again, manual therapy and exercise plus usual care improved, but did not meet the 28-point improvement threshold. In a secondary analysis of this trial by Pinto et al, it was determined that within the New Zealand healthcare system, both manual therapy and exercise offer a significant cost savings over usual care for OA treatment.

With this recent research, there does seem to be a fairly significant benefit to the utilization of manual therapy, however a multi-modal program consisting of manual therapy and exercise seems to be less effective than manual therapy in isolation. It should be taken into consideration that this conclusion was derived from one study and may not be a true representation of the patient population as a whole. In agreement with the benefits of manual therapy found by Abbott et al, a systematic review published by Jansen et al found a greater effect size with manual therapy and exercise (0.69) in comparison to either exercise therapy (0.38) or strength training (0.34) in isolation. Additionally, recent works by Rhon et al and Ko et al found significant increases in proprioception and functional performance when manual therapy was combined with exercise and perturbation exercises, respectively.

In addition to the varying degrees of effectiveness found in the aforementioned studies, it must be considered that not every patient with knee OA will respond similarly to any given therapeutic intervention. In order to help delineate those patients with knee OA who will respond favorably to hip mobilization, Currier et al proposed a Clinical Prediction Rule (CPR) to make this distinction. This particular study found that of those individuals who 2+ of the 5 variables present, following hip mobilization, the positive likelihood ratio was 12.9 and probability of success was 97% (success defined as a decrease of at least 30% on composite Numerical Pain Rating Scale score obtained during functional tests or a Global Rating of Change Scale score of at least 3). This CPR should be used with caution, however, as no validation study has been conducted to this date. While this CPR provides some idea as to which patients will respond favorably to manual therapy interventions, it should be understood that this decision must be made in conjunction with sound clinical reasoning following a thorough patient history and physical examination.

Alexis Wright, PT, PhD, DPT, FAAOMPT goes into great detail with regards to evidence-based decision making when deciding whether joint mobilization or manipulation will benefit your patient in her course, “Evidence-Based Examination of the Hip“. So, while the research is far from definitive regarding this specific intervention, manual techniques do appear to provide significant improvements in proprioceptive capacity, perceived physical disability, and pain levels for patients presenting with knee osteoarthritis.

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