Italy – 17/5/17 – Nadal talks with Almagro as he touches his knee following an injury. REUTERS/Max Rossi
Anterior cruciate ligament (ACL) tears remain one of the most common sports injuries. These injuries typically happen in young athletes dooming them to an 80% chance of developing osteoarthritis (OA) as soon as 10 years after the injury(1,2). Thus, ACL injuries can contribute to life-long disability, with nearly half of those injured never returning to their previous level of sport participation(2). Despite the attention to rehabilitation following an ACL tear, repeated ACL injury incidence remains high(3).
Researchers from the Queen Mary University of London suspected that neuromuscular deficits might be at the root of the high rates of reinjury and OA(1). They conducted a systemic review and meta-analysis to evaluate the short and long-term changes in knee’s neuromuscular function after a knee injury. After an extensive literature search and analysis, they identified 52 studies that met high or moderate inclusion standards. Of those, 46 included patients status-post ACL injury managed conservatively and with various methods of repair.
One of the criteria for study inclusion was healthy controls to compare leg and knee function rather than relying on the ‘healthy’ side as a control. The reasoning was that the ‘healthy leg’ may also experience neuromuscular changes after an injury on the opposite side. Therefore, relying on the standard of the non-injured leg as a return-to-sport criterion may result in insufficient rehabilitation and contribute to the high rate of reinjury.
When the researchers analyzed the studies of ACL injury patients, they found them lacking in measurements of muscles and function other than the quadriceps and hamstrings. The analysis of those muscles found that both demonstrated short and long-term deficits in strength and neuromuscular function. The quadriceps, in particular, failed to recover voluntary activation as well as strength. Thus, even when the swelling and pain resolved and spinal-reflex excitability returned to normal, the patients could not recruit the quadriceps as quickly or easily as the healthy controls. The authors point to decreased cortical excitability hampering the patient’s efforts.
Practical implications
The researchers suggest that the persistent neuromuscular deficits and inability to quickly and precisely produce force within the quadriceps may impact the patient’s risk of suffering another ACL injury more than overall strength. They also implicate the neuromuscular deficits as contributing to the early development of OA. The less than ideal firing and force production from injured leg’s quadriceps may add to the uneven wear and distribution of forces within the joint.
The authors recognize that many of the included articles didn’t report how they recruited subjects, which possibly led to a study population with a high level of bias. They also acknowledge that neuromuscular deficits are a risk factor for knee injuries in healthy populations. In this review, there was no way to know the neuromuscular function of subjects before their injury. In addition, there was a high level of variability in the rehabilitation conducted with the study’s subjects.
However, the results do suggest that the current modes of rehab aren’t sufficiently addressing neuromuscular function. Clinicians need to pay attention to the movement quality and speed of force production in the injured muscles, not just the peak strength. The authors suggest using controlled contractions with low-loads to retrain movement quality. They also recommend heavy resistance and plyometric activities to increase the rate of muscle recruitment and torque development.
Anterior cruciate ligament injuries remain one of the most common sports injuries(1). While sports injury science has made strides toward understanding the causes of injury and prevention strategies, many young athletes still suffer from ACL tears and ruptures. In 2019, sports professionals from various disciplines gathered in Pittsburgh, Pennsylvania, to reach a consensus on the... MORE
Paper Title: A Secondary Injury Prevention Program May Decrease Contralateral Anterior Cruciate Ligament Injuries in Female Athletes: 2-Year Injury Rates in the ACL-SPORTS Randomized Controlled Trial Publication: J Orthop Sports Phys Ther.2020 Sep;50(9):523-530. doi: 10.2519/jospt.2020.9407. Publication Date: Epub 2020 Aug 1 INTRODUCTION: Rehab of athletes after ACL reconstruction surgery (ACL-r) often includes quad strengthening, plyometrics,... MORE
Gluteus medius (GMed)weakness gets blamed for all manner of lower extremity injuries. This broad muscle lies under the gluteus maximus, arises from the ilium’s posterior portion and spans from the iliac crest to the sciatic notch, and attaches on the greater trochanter of the femur. The muscle spreads out like a fan and has three... MORE
There are two reasons why clinicians should consider rehabilitating athletes differently than other individuals. Firstly, athletes are already highly trained with muscular adaptations for their sport. Secondly, they desire to return to a level of performance beyond community-based activity. Therefore, they start with a baseline of strength beyond most individuals, and they need to return... MORE
Children are pushed at younger ages to specialize in a sport and play at an elite (for their age) level. While kids of the same age remain roughly on the same ability level as children, performance gaps become more noticeable as they approach adolescence. It seems obvious that the bigger kids are for their age,... MORE
Dancers are a very elite and specialized kind of athlete. While considered an art form, dance requires a significant amount of athleticism. As such, dancers are prone to athletic injuries, just like other athletes. However, without a personal background in dance, clinicians may be left scratching their heads to determine when dancers are ready to... MORE