Knee Osteoarthritis Functional Classification Scheme – Validation of Time Dependent Treatment Effect. One Year Follow-Up of 518 Patients

Objective: The purpose of the current study was to validate time dependent changes of a novel functional classification for patients with knee osteoarthritis (KOA), following a home-based biomechanical treatment (HBBT).Methods: A retrospective analysis of 518 patients with KOA was conducted. All patients were classified using a novel knee osteoarthritis functional grade (KOFG) classification for KOA, based on spatio-temporal gait analysis. Patients were re-classified after 3 months and 1 year of HBBT to examine and validate this classification using timedependant changes. The time dependent changes in the classification were compared to gold-standard selfassessment questionnaires, WOMAC and short form 36 (SF-36).Results: The changes in KOFG were demonstrated over time, with most changes occurring after 3 months of treatment with consolidation of the effect at 12 months. For example, of 427 patients that were classified in KOFG 2-4 grade at baseline, 44.9% and 51.5% had lower (better) KOFG grades at 3 and 12 months of treatment, respectively. The changes in KOFG were validated with WOMAC and SF-36 questionnaires showing a significant correlation between KOFG changes and changes in WOMAC and SF-36. SF-36 pain sub-scale showed an improvement of 33.0% and 38.0% following 3 months and 12 months of treatment, respectively (p values <0.0001).Conclusions: The results of the current study validate the knee osteoarthritis functional grade classification scheme as a tool to assess time dependant changes in KOA as well as its sensitivity to assess treatment effect. The KOFG can offer a more robust mode of reporting clinical results in describing the natural history and time-dependent treatment results of patients suffering from knee OA and should be considered as an additional outcome measure in future studies.