Step descent strategy is altered bilaterally despite unilateral muscle strength impairment after total knee arthroplasty
Muscle weakness and difficulty descending stairs are common after unilateral total knee arthroplasty (TKA), but the relationship between each is unclear. The purpose of this study was to compare lower extremity muscle strength, lower extremity support moments during step descent, and assess relationships between each.
The study included 40 subjects (20 post-TKA, 20 control). Knee extensor, hip abductor, and hip external rotator strength were measured and biomechanical analyses of step descent performed. Patients with TKA were assessed 3 and 6 months post-surgery.
At 3 and 6 months post-TKA, operated limb hip external rotator and knee extensor strength were impaired compared to the non-operated limb (p < 0.01); however, no between-limb differences were observed during step descent. Compared to the control group, hip external rotator and knee extensor strength, total lower extremity support moment, and knee support moment during step descent were impaired post-TKA (p < 0.05). At 6 months post-TKA, knee extensor and hip external rotator strength correlated with total support moment during step descent (rs = 0.40, 0.41, p < 0.02). Hip abductor and external rotator strength negatively correlated with knee support moment during step descent (rs = − 0.35, − 0.39, p < 0.03).
Persistent operative limb knee extensor and hip external rotator muscle weakness are noted following unilateral TKA. Despite unilateral weakness, bilateral alterations in step descent strategy occur following TKA. Patients with TKA utilize hip musculature to reduce knee muscle demand during step descent, possibly contributing to limitations in long-term step descent performance.
KeywordsTotal knee arthroplasty Stair descent Total support moment Hip strength Quadriceps strength
Total knee arthroplasty
Research reported in the publication was supported by the National Center for Advancing Translational Sciences, National Institutes of Health [grant number TL1TR000115]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
All authors have made substantial contributions to the study. The study was conceptualized by all authors (PK, CJ, SD, BN). Data were acquired and curated by PK and BN, analyzed and interpreted by all authors (PK, CJ, SD, BN). PK drafted the initial manuscript with CJ, SD, and BN each providing critical review for subsequent versions. Lastly, all authors have approved this version of the manuscript to be submitted.
Research reported in the publication was supported by the National Center for Advancing Translational Sciences, National Institutes of Health (grant number TL1TR000115). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Compliance with ethical standards
Conflict of interest
CJ and SD receive research support for projects unrelated to this manuscript from Smith & Nephew, Stryker, and Zimmer Biomet. CJ also receives research support for unrelated projects from Aesculap and Medtronic. SD is a paid consultant for Smith & Nephew. PK and BN have no potential conflicts of interest.
Institutional Review Board approval provided by the University of Kentucky (14-0753-F2L).
- 23.Oatis CA, Li W, DiRusso JM, Hoover MJ, Johnston KK, Butz MK et al (2014) Variations in delivery and exercise content of physical therapy rehabilitation following total knee replacement surgery: a cross-sectional observation study. Int J Phys Med Rehabil Suppl 5:002Google Scholar
- 35.Winter DA (2005) Biomechanics and motor control of human movement, 3rd edn. Wiley, HobokenGoogle Scholar