Background: During the past decades many treatments and devices were developed in attempt to unload the diseased articular surface in knee Osteoarthritis (OA). A novel biomechanical device and treatment methodology (The APOS System) was introduced in order to unload the diseased articular surface during activity (dynamic wedging), strengthen dynamic stabilizers and train neuromuscular control by means of controlled biomechanical perturbations. The purpose of this study is to examine the effectiveness of APOS System in reducing pain and improving function in knee OA patients.

Method: A double blind, randomized, prospective study was performed with 61 knee OA patients, aged 49–83 (66 ±8.1) years and graded 1–4 (3 ±1) according to Kellgren & Lawrence. Patients were randomized into research (active) and control (placebo) groups. All patients under-went 8 weeks of treatment. Patients were examined at baseline and supervised 4 times during the study. Patients in the research group used the biomechanical device that consists of 2 biomechanical elements located under the strategic weight bearing spots of each of the patient’s feet and a mounting and positioning mechanism embedded in designated shoes. The treatment methodology that was applied to the research group included dynamic wedging of the diseased articular surface. Patients in the control group used a placebo device without the biomechanical elements. Patients were assessed at baseline, after 4 weeks and after 8 weeks at the end of the study using Knee Society Score, WOMAC, SF-36, ALF and VAS. The assessment was performed without the examiner knowing the group affiliation of the patient.

Results: The two groups were statistically similar (p> 0.05) at baseline with respect to age, Kellgren& Lawrence classification and all assessed parameters including subscales. Significant difference between groups over time was observed for Knee Score (p< 0.001), Knee Society Function Score (p< 0.001), WOMAC (p< 0.001), SF-36 (p< 0.001), ALF (p< 0.001) and VAS (p< 0.001). Significant improvement was observed in the research group throughout all assessed parameters (measured improvement for Knee Score, Knee Society Function Score, WOMAC, SF-36, ALF and VAS were a multiplication of 1.8, 1.4, 3, 1.4, 1.35 and 2 in the applicable scale respectively). A slight deterioration was observed in the control group throughout all assessed parameters at final assessment.

Conclusion: The findings demonstrate that APOS System is effective and significantly improves function and reduces pain among knee OA patients.