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Knee Surg Sports Traumatol Arthrosc. 2018 Feb;26(2):426-433. doi: 10.1007/s00167-017-4678-4. Epub 2017 Sep 16.

Young athletes after ACL reconstruction with quadriceps strength asymmetry at the time of return-to-sport demonstrate decreased knee function 1 year later.

Author information

1
Movement Analysis and Performance Laboratory, School of Health and Rehabilitation Sciences, The Ohio State University, 2050 Kenny Road, Columbus, OH, USA.
2
OSU Sports Medicine, The Ohio State Wexner Medical Center, Columbus, OH, USA.
3
Sports Medicine Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
4
Division of Physical Therapy, School of Health and Rehabilitation Sciences, The Ohio State University, 453 W 10th Avenue, Atwell Hall, Columbus, OH, USA.
5
Divisions of Occupational and Physical Therapy and Sports Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 10001, Cincinnati, OH, USA.
6
Biomechanics Laboratories and Sports Medicine, Departments of Orthopaedic Surgery, Physical Medicine and Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, RO_GU_01_22, Rochester, MN, USA.
7
Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH, USA.
8
Movement Analysis and Performance Laboratory, School of Health and Rehabilitation Sciences, The Ohio State University, 2050 Kenny Road, Columbus, OH, USA. laura.schmitt@osumc.edu.
9
Sports Medicine Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA. laura.schmitt@osumc.edu.
10
Division of Physical Therapy, School of Health and Rehabilitation Sciences, The Ohio State University, 453 W 10th Avenue, Atwell Hall, Columbus, OH, USA. laura.schmitt@osumc.edu.

Abstract

PURPOSE:

Quadriceps femoris (QF) strength deficits at return-to-sport (RTS) after ACL reconstruction (ACLR) contribute to decreased knee function at the same time point. However, the impact of QF strength at RTS on longitudinal function has not been examined. The purpose of this study was to test the hypothesis that young athletes after ACLR with QF strength asymmetry at RTS would demonstrate decreased knee-related function and lower proportions of functional recovery at 1 year post-RTS compared to young athletes following ACLR with nearly symmetric QF strength at RTS.

METHODS:

Participants included 76 young athletes (74% female; mean age at RTS = 17.3 years) after primary, unilateral ACLR, cleared to RTS, and followed for 1 year after RTS. At the time of RTS, QF strength was quantified on an isokinetic dynamometer and a Limb Symmetry Index (LSI) was calculated [(involved/uninvolved) × 100%]. The cohort was subdivided into two groups based on RTS QF LSI: high quadriceps (HQ; LSI ≥ 90%; n = 36) and low quadriceps (LQ; LSI < 85%; n = 36). The cohort was followed for 1 year post-RTS, and knee-related function was assessed using the International Knee Documentation Committee subjective form (IKDC), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and LSI of single-leg hop tests. Functional recovery at 1 year post-RTS was defined as KOOS scores above literature-reported cut-offs.

RESULTS:

While the HQ group demonstrated higher symmetry on all 1 year post-RTS hop tests, only the triple-hop test (p = 0.020) was found to be statistically different. Similarly, while the HQ group scored higher on all 1 year post-RTS self-reported knee function measures, only differences on the KOOS-Sport/Rec score (p = 0.039) and IKDC score (p = 0.011) were statistically different. Additionally, the HQ group demonstrated higher proportions of functional recovery at 1 year post-RTS than the LQ group on the KOOS-Symptoms (HQ: 88.9%, LQ: 69.4%; p = 0.040) and KOOS-Sport/Rec (HQ: 91.7%, LQ: 69.4%; p = 0.017).

CONCLUSIONS:

Young athletes after ACLR with QF strength asymmetry at RTS demonstrated decreased knee-related function and lower proportions of functional recovery at 1 year post-RTS. However, group differences did not exceed reported minimal clinically important difference values. Further study is warranted to understand factors that contribute to longitudinal knee function after ACLR. Clinicians should focus on restoring symmetric QF strength at RTS after ACLR, which may promote higher longitudinal knee function.

LEVEL OF EVIDENCE:

Level II, Prospective cohort study.

KEYWORDS:

ACL reconstruction; Knee function; Quadriceps strength

PMID:
28918506
DOI:
10.1007/s00167-017-4678-4
[Indexed for MEDLINE]

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