Graduation date: 2007
Lateral heel wedge orthotics are designed to reduce medial tibiofemoral joint loading and pain in patients with knee osteoarthritis (OA). To date, the efficacy of long-term lateral heel wedge orthotics use among OA patients has not been determined. This study evaluated the extent to which lateral heel wedge orthotics reduced medial knee joint loading during walking and stair descent in knee OA patients. A secondary purpose was to measure the effects of lateral heel wedge orthotics on selected health-related quality of life parameters. A cohort of 36 men and women with moderate to severe medial knee OA were assigned to either an Orthotics group (mean age, 60.8 ± 9.8 yrs; mean BMI, 28.1 ±3.71) or Control group (mean age, 61.0 ± 9.2 yrs; mean BMI, 28.0 ± 4.3). The Orthotics group wore a pair of custom-made 7° lateral heel wedges daily for 12 weeks. The Control group wore a pair of neutral inserts for 12 weeks. Pain and functional levels were assessed using a 100-mm visual analog pain scale and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC™). Three-dimensional kinematic and kinetic data during level walking and stair descent were collected using a nine-camera motion analysis system synchronized with two strain gauge force plates. Subjects performed 5 walking trials and 5 stair descent trials at 3 different speeds, e.g., self-selected pace, slower, and faster. Biomechanical and health-related quality of life data were collected from subjects at baseline, 6 weeks and 12 weeks. Using inverse dynamics equations, lower extremity joint moments and angles were calculated. Eleven dependent variables were analyzed with univariate Group (2) x Time (3) between/within ANOVAs. A weighted Bonferroni adjustment was used to protect against Type I error. During level walking trials, the early stance peak external knee adduction moment decreased 14.6% in the Orthotics group from Week 1 to Week 12 (p < 0.05). The WOMAC™ pain and activities of daily living subscale scores decreased in both the Orthotics and Control groups throughout the study (p< 0.05). During stair descent, the peak knee adduction moment was not different between Groups or Time during stair descent trials (p > 0.05). However, at Week 12 subjects in the Orthotics group had an average 47% reduction in self-reported pain levels during stair descent compared with their pain scores at entry into the study (p = 0.038). These findings suggest that lateral heel wedge orthotics can effectively lower medial knee joint loading for OA patients during level walking, while also reducing pain during the difficult task of descending stairs.