Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Sep 4;12(9):23259671241264845.
doi: 10.1177/23259671241264845. eCollection 2024 Sep.

Predicting the Recovery of Isokinetic Knee Strength 6 Months After Anterior Cruciate Ligament Reconstruction

Markus Wenning  1   2 , Ghislain N Sofack  3 , Daniela Zöller  3 , Marlene Mauch  4   5 , Albrecht H Heitner  4 , Jochen Paul  4 , Peter Zahn  1 , Ramona Ritzmann  4   6
Affiliations

Predicting the Recovery of Isokinetic Knee Strength 6 Months After Anterior Cruciate Ligament Reconstruction

Markus Wenning et al. Orthop J Sports Med. .

Abstract

Background: The limb symmetry index (LSI) is a metric of strength restoration. It is key to successfully return to sports after anterior cruciate ligament (ACL) reconstruction. The threshold for return to sports is generally considered an LSI of ≥85%.

Purpose: To develop a statistical model for predicting the recovery of knee extension and flexion strength (with LSI ≥85%) at 6 months after ACL reconstruction.

Study design: Case-control study; Level of evidence: 3.

Methods: Patients who underwent arthroscopic ACL reconstruction between November 2015 and December 2020 were included. The patients were classified into 2 groups: "pass" if the LSI at 6 months postoperatively was ≥85% and "fail" if the LSI was <85%. Factors in 25 categories with 74 levels, including patient characteristics, periarticular procedures, intra-articular lesions and treatment, and perioperative management, were collected. A multivariable logistic regression combined with backward variable elimination was used to determine the predictive parameters for recovery of knee extension and flexion strength.

Results: A total of 948 patients were included. Graft site, preoperative isokinetic strength, treatment of meniscal injury, and injured side (left vs right) were identified as general predictors for both knee extension and flexion strength. For knee extension strength, age at injury and partial weightbearing duration were identified as additional predictors. For knee flexion strength, type of meniscal injury, surgeon volume, cartilage procedures, and periarticular procedures were identified as additional predictors. The Nagelkerke R 2 of the final model was 0.178, and the c-statistic was 0.716 (95% CI, 0.676-0.754). The Hosmer-Lemeshow test indicated good calibration (P = .879).

Conclusion: Several factors including preoperative isokinetic strength, treatment of meniscal injuries, left vs. right side and graft site were found to predict recovery of ≥85% LSI in knee extension and flexion strength. Despite the numerous factors that were analyzed, the predictive power was moderate (c-statistic = 0.716), indicating there were other nonincluded factors that significantly influence strength performance at 6 months postoperatively.

Keywords: ACL reconstruction; isokinetic strength; prediction model; return to sports.

PubMed Disclaimer

Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: This study was partially financed by Praxisklinik Rennbahn M.W. was supported by the Berta-Ottenstein Program for clinician scientists of the Faculty of Medicine at the University of Freiburg. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto. Ethical approval for this study was obtained from Ethikkommission Nordwest und Zentralschweiz (ref No. 2017-01825).

Figures

Figure 1.
Figure 1.
Plot showing odds ratios of the isolated factors predicting LSI ≥85% for knee extension strength at 6 months postoperatively. LSI, limb symmetry index; MM, medial meniscus; QT, quadriceps tendon; ST, semitendinosus.
Figure 2.
Figure 2.
Plot showing odds ratios of the isolated factors predicting LSI ≥85% for knee flexion strength at 6 months postoperatively. LSI, limb symmetry index; QT, quadriceps tendon; ST, semitendinosus.
See this image and copyright information in PMC

References

    1. Ahmad SS, Schreiner AJ, Hirschmann MT, et al. Dynamic intraligamentary stabilization for ACL repair: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2019;27(1):13-20. - PubMed
    1. Alba AC, Agoritsas T, Walsh M, et al. Discrimination and calibration of clinical prediction models: users’ guides to the medical literature. JAMA. 2017;318(14):1377. - PubMed
    1. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. Br J Sports Med. 2011;45(7):596-606. - PubMed
    1. Ashigbi EYK, Banzer W, Niederer D. Return to sport tests’ prognostic value for reinjury risk after anterior cruciate ligament reconstruction: a systematic review. Med Sci Sports Exerc. 2020;52(6):1263-1271. - PubMed
    1. Balendra G, Jones M, Borque KA, Willinger L, Pinheiro VH, Williams A. Factors affecting return to play and graft re-rupture after primary ACL reconstruction in professional footballers. Knee Surg Sports Traumatol Arthrosc. 2022;30(7):2200-2208. - PubMed

LinkOut - more resources