Examining Shibboleths of Hip Rehabilitation Protocols Using in vivo Contact Pressures from an Instrumented Hemiarthroplasty

Abstract

Summary This study uses acetabular contact pressure data from the immediate post-operative period to examine some of the commonly held beliefs about early phase hemiarthroplasty rehabilitation. Data were obtained from an instrumented femoral head prosthesis implanted in an 82-year-old man (height 1.6 m; weight 54.5 kg) with a displaced left hip fracture. Data were collected daily during the two weeks of immediate post-operative hospitalisation. The shibboleths being examined are related to the functional activities: sit-to-stand, ambulation, and stair-climbing. Results support beliefs about rising from a chair: lower pressures were created when rising from a 62 cm hip chair (1.4 MPa) than from a 48 cm standard chair (7.09 MPa): and less pressure was created when rising from a 62 cm hip chair with operated leg out in front (1.21 MPa) than when rising from the same chair with feet together (2.96 MPa). Gait training beliefs are challenged by the study findings: there was no significant difference between touch weight bearing, partial weight bearing, and weight bearing as tolerated; and use of a very commonly used post-operative gait sequence (walker, then operated leg, then non-operated leg) generated a greater peak pressure than an ‘incorrect’ sequence (walker, then non-operated leg, then operated leg). Limited early post-operative stairs data prevented definitive conclusions from being reached about stair-climbing in the early post-operative period. However, examination of data from one year post-operatively demonstrates that unassisted reciprocal gait on stairs creates large (15.52 MPa) acetabular contact pressures. This study uses acetabular contact pressure data from the immediate post-operative period to examine some of the commonly held beliefs about early phase hemiarthroplasty rehabilitation. Data were obtained from an instrumented femoral head prosthesis implanted in an 82-year-old man (height 1.6 m; weight 54.5 kg) with a displaced left hip fracture. Data were collected daily during the two weeks of immediate post-operative hospitalisation. The shibboleths being examined are related to the functional activities: sit-to-stand, ambulation, and stair-climbing. Results support beliefs about rising from a chair: lower pressures were created when rising from a 62 cm hip chair (1.4 MPa) than from a 48 cm standard chair (7.09 MPa): and less pressure was created when rising from a 62 cm hip chair with operated leg out in front (1.21 MPa) than when rising from the same chair with feet together (2.96 MPa). Gait training beliefs are challenged by the study findings: there was no significant difference between touch weight bearing, partial weight bearing, and weight bearing as tolerated; and use of a very commonly used post-operative gait sequence (walker, then operated leg, then non-operated leg) generated a greater peak pressure than an ‘incorrect’ sequence (walker, then non-operated leg, then operated leg). Limited early post-operative stairs data prevented definitive conclusions from being reached about stair-climbing in the early post-operative period. However, examination of data from one year post-operatively demonstrates that unassisted reciprocal gait on stairs creates large (15.52 MPa) acetabular contact pressures.