Question: In patients with symptomatic osteoarthritis (OA) of the knee associated with a valgus deformity, do medial-wedge insoles reduce joint pain and improve function and alignment?
Design: Randomized (allocation not concealed), blinded (patients, clinician, and outcome assessors) controlled trial with follow-up at 8 weeks.
Setting: Rheumatology Division of the University of São Paulo, São Paulo, Brazil.
Patients: 30 women (mean age, 62 y) who had knee OA (according to American College of Rheumatology criteria) with bilateral valgus deformities =8°. Inclusion criteria were lateral compartment involvement detected on radiographs (grade =2 on the Kellgren-Lawrence [K-L] scale), absent or minimal involvement (K-L grade 0 or 1) in the medial compartment, and pain on movement (a score of =2 on visual analog scale [VAS]). Exclusion criteria were body mass index =40 kg/m2, scoliosis, a >1-cm difference in lower-limb length, knee surgery, hallux rigidus, rheumatologic disease, soft-tissue involvement, foot or lower-leg symptoms, or use of corticosteroid or hyaluronic acid infiltrations within 3 or 6 months, respectively, before study entry. All patients completed the study.
Intervention: Patients were allocated to shoes with medial-wedge insoles (n = 16) or neutral insoles (n = 14). Medial-wedge insoles had an 8-mm-high wedge at the rear of the insole. Neutral insoles were identical but without the raised wedge. All patients received the same new shoes and used commercial neoprene elastic banding for ankle support. Patients wore the shoes and elastic banding for 3 to 6 hours per day.
Main outcome measures: Pain was assessed by VAS at night, at rest, and on movement. The Western Ontario and McMaster Universities Osteoarthritis (WOMAC) and Lequesne scales were used to assess pain and functioning. An improvement of >20% in WOMAC and Lequesne scores was defined as a clinically meaningful change. Femorotibial, talocalcaneal, and talar tilt angles were also evaluated at baseline and at the time of the 8-week follow-up.
Main results: Patients in the medial-wedge insole group showed a significant reduction in pain from baseline in all outcome measurements (VAS, WOMAC, and Lequesne; p = 0.002). Patients in the neutral insole group had a significant reduction from baseline only in night pain (p = 0.019). The percent changes in pain on movement and at night and in the WOMAC and Lequesne scores were greater in the medial-wedge insole group than in the neutral insole group (Table). A clinically meaningful change was seen in more patients in the medial-wedge insole group than in the neutral insole group by WOMAC score (100% vs 57%, p = 0.005). The difference between groups for Lequesne index did not reach significance (100% vs 79%, p = 0.09). A significant increase from baseline occurred in femorotibial angle in the medial-wedge insole group (169.0 vs 170.8, p = 0.001) compared with no change in the neutral insole group (171.3 vs 171.3, p = 0.47). No changes in talar tilt or talocalcaneal angles were seen in either group.
Conclusion: In patients with symptomatic osteoarthritis of the knee with valgus deformity, medial-wedge insoles were more effective than neutral insoles at reducing pain and improving function.
This randomized trial evaluated the effect of medial-wedge insoles on joint pain, function, and alignment in patients with symptomatic osteoarthritis of the knee with valgus deformity. The purpose of medial-wedge insoles is to transfer load from the lateral to the medial compartment of the knee joint. At 8 weeks, the authors noted improvements in VAS pain scores and in WOMAC scores in the patients who were using medial-wedge insoles.
The strengths of this study were that it was a randomized trial, the assessors were blinded, the patients were evaluated with use of validated scoring systems, and all patients received new shoes and some received the medial-wedge insoles.
The study has several potential weaknesses. First, only 30 patients were randomized. Second, the activity levels of the patients were not delineated, so it is difficult to determine which patients would most likely benefit from this therapy. Third, it was not clear if the patients used other treatments for their knee pain during the course of the study. Patients only wore the insoles for 3 to 6 hours per day and the type of footwear worn at other times was not assessed, so this could have influenced the results. Fourth, the etiology of the osteoarthritis and the valgus deformity was not delineated in this study. Finally, the patients were only studied for 2 months.
Osteoarthritis of the knee with valgus deformity is a common condition. There are a number of different options for the management of patients with osteoarthritis of the knee. Although a larger randomized trial with a longer term of follow-up would be useful, the results of this study suggest that a relatively simple device, a medial-wedge insole, can provide at least short-term pain relief for patients with lateral compartment osteoarthritis of the knee.