Symmetry Restoration and Functional Recovery Before and After Anterior Cruciate Ligament Reconstruction

Logerstedt D, Lynch A, Axe MJ, Snyder-Mackler L. Knee Surg Sports Traumatol Arthrosc. 2012 Feb 21. [Epub ahead of print]

Restoration of function after anterior cruciate ligament reconstruction (ACLR) is paramount for return-to-sport and long-term health of the knee joint. During rehabilitation, clinical measures of quadriceps strength and hop performance along with self-reported outcome measures have been used to evaluate improvements in function but we don’t know when these measures return to “normal” with rehabilitation before and after surgery. Furthermore, it is not clear how much improvement in limb symmetry, based on quadriceps strength and hop performance, is meaningful. Therefore, the purpose of this study was to identify how limb symmetry, based on using quadriceps strength and hop measures, changes during rehabilitation. Eighty-three athletes’ participating in sports involving cutting, pivoting and jumping activities were examined for this study. All athletes underwent pre-ACLR rehabilitation including strengthening and perturbation training (PERT). Functional measures of quadriceps strength, hop performance and self-reported outcome measures were collected at baseline (after injury but before pre-operative rehabilitation), after pre-operative PERT training (prior to surgery), as well as 6 and 12 months after ACLR. Quadriceps strength was tested through maximum voluntary isometric contraction with burst superimposition technique [Snyder-Mackler, 1995]. Four single leg hop tests, as previously described by Noyes et al, were used to evaluate limb symmetry (involved limb’s results divided by uninvolved limb’s results) with ≥90% limb symmetry considered normal knee function, based on normal subject values [Risberg, 1995]. Self-reported questionnaires were used to evaluate the patients’ perception of knee function; Knee Outcome Survey-Activities of Daily Living (KOS-ADLs), International Knee Documentation Committee 2000 (IKDC 2000) and Global Rating Scale (GRS). Quadriceps strength measures of the involved limb (surgical limb) at baseline were weaker than the uninvolved limb (contralateral healthy limb). However, quadriceps strength improved overtime and there were no differences between limbs after baseline measures. The involved limb for all subjects hop scores, except the cross-over hop, improved more than the uninvolved limb and all scores improved from baseline to 12 months after ACLR. Despite the improvements, at 6 months after ACLR 19 to 23% of individuals did not achieve normal knee function based on ≥90% limb symmetry on hop measures and 5 to 11% of individuals did not achieve this score at 12 months. Similarly, 25% and 13% of individuals had IKDC2000 scores below normal ranges at 6 month and 12-month post-ACLR; respectively. Small changes in all outcome measures occurred from 6 to 12 months after surgery.

While perturbation training and quadriceps strengthening was capable of improving limb symmetry in many patients not all individuals achieved ≥90% limb symmetry at 6 and 12 months after surgery. Six months after surgery, when individuals are typically cleared to return-to-sport, up to 23% of individuals in this study did not achieve ≥90% limb symmetry. Furthermore, at 12 months after surgery 5 to 11% of individuals still had not achieved 90% limb symmetry. This may be concerning since it is speculated that these asymmetries, tested during controlled dynamic hopping tasks, may be magnified during opposed athletic play. However, it is important to note that there is insufficient evidence to suggest that individuals that do not achieve this 90% cut-off have poorer outcomes. A recent systematic review determined that consistent return-to-sport criteria are lacking for this population [Barber-Westin, 2011].  Self-reported questionnaires and objective assessments of limb symmetry may become an important components for return-to-sport criteria. Based on normal values of ≥90% [Risberg, 1995], not all individuals achieve limb symmetry at 6 and 12 months. Do you think this cut-off is sufficient to determine when return-to-sport is appropriate? Or is 90% not strict enough?    

Written by: Kathleen White
Reviewed by: Jeffrey Driban  

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Logerstedt D, Lynch A, Axe MJ, & Snyder-Mackler L (2012). Symmetry restoration and functional recovery before and after anterior cruciate ligament reconstruction. Knee Surgery, Sports Traumatology, Arthroscopy PMID: 22349604