Department of Kinesiology and Health, Northern Kentucky University, Highland Heights, KY, USA
Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, HI, USA
Straub Bone and Joint Center, Straub Hospital and Clinic, Honolulu, HI, USA
Corresponding author: Rachele E. Vogelpohl, PhD, ATC, Department of Kinesiology and Health, Northern Kentucky
University, 109 HC Nunn Drive, Highland Heights, KY 41099, USA. Tel.: +1 859 572 5623; Fax: +1 859 572 6090; E-mail: [email protected].
Abstract: BACKGROUND: The direct anterior (DA) total hip arthroplasty (THA) is a minimally invasive procedure that accesses the hip joint from the anterior aspect of the hip by retracting instead of incising muscles during surgery. The lack of soft tissue damage is thought to result in an accelerated return of strength and function. PURPOSE: The purpose of this study was to identify when participants undergoing DA regained normal strength and function. METHODS: Twenty DA and 14 controls participated in this prospective study. Maximum isometric hip strength was measured in all hip motions using a hand-held dynamometer. Function was assessed using the Timed Up and Go (TUG) test and the Trendelenburg Single-Leg Balance (SLB) test. Data were collected at pre-operation, three and six weeks, and three months post-operation. MAIN RESULTS: At three and six weeks post-operation, all strength values except for hip adduction were significantly lower than the control group. By three months, only hip external rotation remained significantly lower in the DA group (p = 0.04; DA: 0.86 ± 0.54 N/BW, Control: 1.22 ± 0.37 N/BW). At three and six weeks post-operation, all strength values except for hip extension and external rotation were more asymmetrical than the control group. By three months post operation, only hip flexion remained more asymmetrical (p = 0.03, DA: –1.11 ± 2.04, Control: 0.55 ± 2.24). There were significant time effects for Trendelenburg SLB test (p = 0.04) and TUG (p = 0.003), but post hoc testing revealed no further differences. CONCLUSIONS: The results indicate that an emphasis on improving hip flexion and external rotation strength may be valuable in regaining normal strength and function in the DA population.
Keywords: Direct anterior total hip arthroplasty, hip isometric strength, functional measures