BMI, Pain, and Gait Predict Odds of Hip Replacement

April 28, 2014

(OARSI 2014) More reasons to stay slim: A small prospective study finds that people with moderate hip osteoarthritis who have hip replacement within a decade are larger and have less normal gait.

Analysis of gait and function has identified patients with mild to moderate hip osteoarthritis (OA) who will progress to total hip replacement, by and large confirming what a physician might guess: Patients who are heavier and in greater discomfort, with a less normal gait, are more likely to have hip replacements within a decade.

This small study by a team from Norway observed the natural history of hip OA in 43 subjects, usinig gait analysis at baseline and again six or seven years later. A camera and force plate motion analysis system measured initial contact, mid-stance peak, hip extension angle and toe-off, and joint space was assessed from postero-anterior digital pelvic radiographs.

The team also evaluated self-reported pain, stiffness, and function using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) hip range of motion and the six-minute walk tests.

After seven years, 31 patients had undergone total hip replacement surgery. Comparing the baseline measurements of those 31 patients to those of the 12 patients who did not have surgery, the latter initially had lower body mass index (BMI), larger minimal joint space, and better self-reported WOMAC function (and less stiffness). During gait, the 12 started with larger hip- and knee-joint excursion and a larger hip flexion moment during the final 50% of stance.

At followup, these 12 had no signs of disease progression.