Strength normalized to muscle volume rather than body weight is more accurate for assessing knee strength following anterior cruciate ligament reconstruction

Article type: Research Article

Authors: Ohji, Shunsuke^{a; *} | Aizawa, Junya^b | Hirohata, Kenji^a | Ohmi, Takehiro^a | Mitomo, Sho^a | Koga, Hideyuki^c | Yagishita, Kazuyoshi^a

Affiliations: [a] Clinical Center for Sports Medicine and Sports Dentistry, Tokyo Medical and Dental University, Tokyo, Japan | [b] Department of Physical Therapy, Juntendo University, Tokyo, Japan | [c] Department of Joint Surgery and Sports Medicine, Tokyo Medical and Dental University, Tokyo, Japan

Correspondence: [*] Corresponding author: Shunsuke Ohji, Clinical Center for Sports Medicine and Sports Dentistry, Tokyo Medical and %****␣ies-30-ies210132_temp.tex␣Line␣25␣**** Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. Tel.: +81 358 034 721; Fax: +81 358 034 720; E-mail: ohji.spt@tmd.ac.jp.

Abstract: BACKGROUND: Knee strength weakness is a major problem frequently observed in patients during postoperative rehabilitation following anterior cruciate ligament reconstruction (ACLR). OBJECTIVE: To investigate whether knee strength normalized to muscle volume could better detect side-to-side differences than that normalized to body weight following ACLR. METHOD: This study included 17 patients who had undergone primary ACLR (11.6 ± 2.3 months). Body weight and total muscle volume were measured using a bioelectrical impedance analysis composition scale. Isokinetic knee extension and flexion moment were measured at 60∘/s and 180∘/s, respectively. Bivariate correlation analysis was used to examine correlations between body composition and knee strength. Differences in knee strength between the operated and unoperated legs were analyzed using a paired t-test, which calculated the effect size. RESULTS: There was a significant correlation between knee strength and body weight (r= 0.53–0.67); however, a stronger correlation was observed between knee strength and total muscle volume (ρ= 0.80–0.87). The effect size was larger for knee strength expressed as % total muscle volume than for knee strength expressed as % body weight. CONCLUSION: Strength expressed as % total muscle volume may be more accurate than that expressed as % body weight for detecting side-to-side differences in knee strength following ACLR.

Keywords: ACL reconstruction, isokinetic moment, isokinetic strength, muscle mass

DOI: 10.3233/IES-210132

Journal: Isokinetics and Exercise Science, vol. 30, no. 1, pp. 7-13, 2022