Intracapsular pressure and elasticity of the hip joint capsule in osteoarthritis.

We investigated intracapsular pressure and elasticity of the hip joint capsule in osteoarthritis. HOOS hip score, sonography of the hip joint, and radiographic assessment of osteoarthritis were performed in 31 patients before total hip arthroplasty. The intracapsular hydrostatic pressure was measured perioperatively, and 0.9% saline solution was then injected in the hip joint, 1 mL at a time, with continuous pressure recording up to 300 mm Hg. The mean radiographic grade of severity of osteoarthritis was 8 (SD, 2.4). The mean hydrostatic intracapsular pressure in 45 degrees of flexion was 2.2 mm Hg (SD, 10.0); in extension, 15.8 mm Hg (SD, 33.0); in inward rotation, 13.7 mm Hg (SD, 26.0); and in outward rotation, 12.1 mm Hg (SD, 24.3). Severe osteoarthritis was associated with lower intracapsular pressure and lower elasticity of the joint capsule.