VA Research and Development LOGO

Logo for the Journal of Rehab R&D
Volume 43 Number 4, July/August 2006
Pages 435 — 444

Abstract - Isometric performance following total hip arthroplasty and rehabilitation

Karen L. Frost, PhD;1* Gina E. Bertocci, PhD;2 Craig A. Wassinger, MS, PT;3 Michael C. Munin, MD;3-4
Ray G  . Burdett, PhD, PT;3 Shirley G . Fitzgerald, PhD1,5

1Injury Risk Assessment and Prevention Laboratory and 2Department of Mechanical Engineering, University of Louisville, Louisville, KY; 3School of Health and Rehabilitation and 4Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA; 5Department of Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA
Abstract-We compared differences in isometric strength between older adults who have undergone elective unilateral total hip arthroplasty (THA) and completed rehabilitation with a population of community-dwelling older adults who have not had THA. The study was a cross-sectional design, and 22 unilateral THA subjects and 38 community-dwelling older adults participated. THA subjects received on average 13 outpatient or home-based physical therapy sessions before evaluation. THA subjects were evaluated 4 to 5 months postsurgery. We assessed isometric muscle strength by measuring peak hip torque per body weight with a robotic dynamometer during abduction, flexion, and extension. No significant performance differences were observed between operated and nonoperated hips of THA subjects. THA subject operated and nonoperated hips generated significantly less peak torque per body weight during flexion (p = 0.03) compared with community-dwelling older adult hips (THA subject operated hips = 6.96 ft-lb/lb, THA subject nonoperated hips = 8.26 ft-lb/lb, community-dwelling older adult hips = 11.56 ft-lb/lb). No significant differences were observed between THA subjects and community-dwelling older adults during hip extension (p = 0.55) or abduction (p = 0.17). At 4 to 5 months postsurgery, THA subjects were not at the same level of biomechanical performance as community-dwelling older adults. Significant strength deficits were found in THA subject operated versus nonoperated hips during isometric flexion. Additional or modified physical therapy that targets the hip flexors is recommended after THA.
Key words: arthroplasty, biomechanical performance, hip replacement, hip strength, isometric performance, muscle strength, osteoarthritis, physical therapy, rehabilitation, strength deficit.

go to Contents Page for Volume 43, No 3
go to HTML version of this article
go to PDF version of this article