Design of patient-specific gait modifications for knee osteoarthritis rehabilitation

Abstract

Gait modification is a nonsurgical approach for reducing the external knee adduction torque in patients with knee osteoarthritis (OA). The magnitude of the first adduction torque peak in particular is strongly associated with knee OA progression. While toeing out has been shown to reduce the second peak, no clinically realistic gait modifications have been identified that effectively reduce both peaks simultaneously. This study predicts novel patient-specific gait modifications that achieve this goal without changing the foot path. The modified gait motion was designed for a single patient with knee OA using dynamic optimization of a patient-specific, full-body gait model. The cost function minimized the knee adduction torque subject to constraints limiting how much the new gait motion could deviate from the patient's normal gait motion. The optimizations predicted a "medialthrust" gait pattern that reduced the first adduction torque peak between 32% and 54% and the second peak between 34% and 56%. The new motion involved three synergistic kinematic changes: slightly decreased pelvis obliquity, slightly increased leg flexion, and slightly increased pelvis axial rotation. After gait retraining, the patient achieved adduction torque reductions of 39% to 50% in the first peak and 37% to 55% in the second one. These reductions are comparable to those reported after high tibial osteotomy surgery. The associated kinematic changes were consistent with the predictions except for pelvis obliquity, which showed little change. This study demonstrates that it is feasible to design novel patient-specific gait modifications with potential clinical benefit using dynamic optimization of patient-specific, full-body gait models. Further investigation is needed to assess the extent to which similar gait modifications may be effective for other patients with knee OA.

Knee contact forces are not altered in early knee osteoarthritis

“…In agreement with this statement, aberrant knee joint loading has been identified as a factor affecting the progression of knee OA (13)(14)(15) in more advanced stages of OA (16): increased medial compartment loading has been associated with more pronounced clinical symptoms and OA severity as assessed by radiography (24,25). Most studies (17)(18)(19)(20)(21)(22)(23)(24) used the knee adduction moments (KAM), i.e. the external knee joint moment in the frontal plane was used as an indirect measure of medial compartment loading during functional activities.…”

Correlation between the knee adduction torque and medial contact force for a variety of gait patterns

“…Second, clinicians should consider conservative interventions such as strengthening of the quadriceps 29,30 and iliotibial band 31,32 or gait retraining 33,34 to lower the adduction torque to below the target level. For example, a medial thrust gait motion designed in a recent computational study has been shown to reduce the peak adduction torque by 35-50%, 35 an amount comparable to HTO surgery, in the one patient studied thus far. To implement these suggestions, clinical gait labs would need to play a central role in initial screening, treatment design, and evaluation of treatment efficacy.…”

Gait modification strategies for altering medial knee joint load: A systematic review

“…No RCTs were identified, and with the exception of 2 studies (26,27), none implemented modifications over the longer term. Studies lacked an adequate description of procedures, the modification implemented, the training methods, and the evaluation of skill acquisition.…”

“…Most studies evaluated the overall or early-stance peak KAM (Table 2). Twelve studies reported early-stance peak KAM values (27,30 -33,35,43-46,48,49), with late-stance peak KAM values reported in 6 studies (27,30,32,33,35,45). Point estimates and measures of variability were not reported for 1 study and could not be extracted from graphical data (36).…”