Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction

Orthopaedic Journal of Sports Medicine, Mar 2015

Background: Criteria for return to unrestricted activity after anterior cruciate ligament (ACL) reconstruction varies, with some using time after surgery as the sole criterion—most often at 6 months. Patients may have residual neuromuscular deficits, which may increase the risk of ACL injury. A single-leg squat test (SLST) can dynamically assess for many of these deficits prior to return to unrestricted activity.

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Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction

Downloaded from ojs.sagepub.com by guest on September Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction Michael P. Hall Ronald S. Paik Anthony J. Ware Karen J. Mohr Orr Limpisvasti Los Angeles California Background: Criteria for return to unrestricted activity after anterior cruciate ligament (ACL) reconstruction varies, with some using time after surgery as the sole criterion-most often at 6 months. Patients may have residual neuromuscular deficits, which may increase the risk of ACL injury. A single-leg squat test (SLST) can dynamically assess for many of these deficits prior to return to unrestricted activity. Hypothesis: A significant number of patients will continue to exhibit neuromuscular deficits with SLST at 6 months after ACL reconstruction. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients using a standardized accelerated rehabilitation protocol at their 6-month follow-up after primary ACL reconstruction were enrolled. Evaluation included bilateral SLST, single-leg hop distance, hip abduction strength, and the subjective International Knee Documentation Committee (IKDC) score. Results: Thirty-three patients were enrolled. Poor performance of the operative leg SLST was found in 15 of 33 patients (45%). Of those 15 patients, 7 (45%) had concomitant poor performance of the nonoperative leg compared with 2 of 18 patients (11%) in those who demonstrated good performance in the operative leg. The poor performers were significantly older (33.6 years) than the good performers (24.2 years) (P ¼ .007). Those with poor performance demonstrated decreased hip abduction strength (17.6 kg operative leg vs 20.5 kg nonoperative leg) (P ¼ .024), decreased single-leg hop distance (83.3 cm operative leg vs 112.3 cm nonoperative leg) (P ¼ .036), and lower IKDC scores (67.9 vs 82.3) (P ¼ .001). Conclusion: Nearly half of patients demonstrated persistent neuromuscular deficits on SLST at 6 months, which is when many patients return to unrestricted activity. Those with poor performance were of a significantly older age, decreased hip abduction strength, decreased single-leg hop distance, and lower IKDC subjective scores. Clinical Relevance: The SLST can be used to identify neuromuscular risk factors for ACL rupture. Many patients at 6 months have persistent neuromuscular deficits on SLST. Caution should be used when using time alone to determine when patients can return to unrestricted activity. anterior cruciate ligament; return to unrestricted activity; single-leg squat test; neuromuscular evaluation - Substantial research has supported neuromuscular deficits to be risk factors for anterior cruciate ligament (ACL) rupture.24-26,48,54,59 Increased valgus loading of the knee and deficits in trunk stability have both been shown to predict ACL injury with high sensitivity and specificity in female athletes.8,25,26,39,54,58,59 Recent kinematic research has now supported a link between increased knee abduction forces and lateral trunk displacement during noncontact ACL injuries.2,6,26,27 This association has provided a strong rationale for the development of trunk- and corebased strengthening programs, which have demonstrated a decreased risk of ACL injury.17,18,20,23,26,37,56 This open-access article is published and distributed under the Creative Commons Attribution - NonCommercial - No Derivatives License (http://creativecommons.org/ licenses/by-nc-nd/3.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the original author and source are credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For reprints and permission queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav. 1 Downloaded from ojs.sagepub.com by guest on September 7, 2016 In addition to preventing ACL injury, preventing reinjury after ACL reconstruction is a concern for orthopaedic surgeons. The risk of ACL rerupture is substantially higher than it is prior to the initial ACL injury,22,44,47,50,52 and traumatic rerupture after ACL reconstruction is the most common mechanism of failure in the first 2 years postoperatively.57 Increasing emphasis is being placed on postoperative rehabilitation, as increased rerupture rates have been observed when deficits in postural stability and hip dynamics are not addressed.22,45 Currently, there is little evidence-based guidance on appropriate criteria, including in-office screening, for determining readiness for return to play after ACL reconstruction. A single-leg squat test (SLST) is used as an indicator of residual deficits in hip abduction strength and pelvic stability and has been used in baseball players returning from shoulder injury.12,34 There is a correlation between performance on SLST and hip abductor function.5,12,31,35 Hip abductor weakness increases the risk of AC (...truncated)


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Michael P. Hall, Ronald S. Paik, Anthony J. Ware, Karen J. Mohr, Orr Limpisvasti. Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction, Orthopaedic Journal of Sports Medicine, 2015, 3/3, DOI: 10.1177/2325967115575900