Leg length discrepancy and osteoarthritic knee pain in the elderly: an observational study.

CONTEXT Osteoarthritic knee pain is very common, as are leg length discrepancies (LLDs). The relationship between LLDs and osteoarthritic knee pain is not well understood. OBJECTIVE To confirm a clinical impression that osteoarthritic knee pain is more common in the short (ie, superior-presenting) leg, as measured by supine physical examination of 3 bony landmarks: the medial malleoli, the anterior superior iliac spines, and the iliac crests. The secondary objective was to measure the relative positions of the 3 bony landmarks to better understand functional contributions to LLD. METHODS A prospective single-occasion observational design was used. Patients who reported osteoarthritic knee pain during an office visit were recruited, and data were collected on 3 bony landmarks and which knee was usually most painful. RESULTS Of the 32 participants who were recruited, 28 were women and 4 were men. Of the 17 participants who reported having right knee pain, 10 had a short right leg and 7 had a short left leg. Of the 15 participants who reported having left knee pain, 13 had a short left leg, 1 had a short right leg, and 1 had equal leg lengths. Knee pain was most severe in the short leg for 23 of 32 participants (71.9%). The most common pattern was for both iliac crests to be equal and the short leg to be concordant with a superior anterior superior iliac spine, which occurred in 23 of 32 participants (71.9%). In the present study population, the magnitude of LLD ranged from 0 to 2.1 cm. CONCLUSION Osteoarthritic knee pain was more common in the apparent short leg. More sophisticated studies, including investigations into the role of pelvic torsion in knee pain, as well as investigations for interoperator reliability and validity, are needed to build on the findings reported in this observational study.