In vivo acetabular contact pressures during rehabilitation, Part I: Acute phase.

The authors conducted a two-part study to compare in vivo acetabular contact pressures during the acute and postacute phases of rehabilitation. This report compares in vivo acetabular contact pressures generated during selected "inpatient" rehabilitation activities and their relationship to pain, range of motion, and other clinical indicators. A pressure-instrumented Moore-type endoprosthesis was implanted in a 73-year-old woman who had sustained a femoral neck fracture. Acetabular contact pressures during the first 2 weeks after surgery were rank-ordered. Clinical data, including range of motion, manual muscle test grade, use of pain medication, and independence in gait, were collected simultaneously. Acetabular pressures did not follow the predicted rank order corresponding to the commonly prescribed temporal order of inpatient rehabilitation activities. Isometric hip extension and active hip flexion generated the highest pressures of all the studied activities, including those measured during gait activities. Isometric exercises, therefore, may not be entirely benign preparation for ambulatory activity. Clinical data did not correspond with peak pressure data, suggesting that observed responses to rehabilitation may not be dependable criteria for progressing the acute hip rehabilitation protocol. We discuss applications for rehabilitation programs based on hip contact pressure data as an initial attempt to formulate more defensible rehabilitation approaches for patients with acutely painful hips.