Predicting Who Needs Surgery After ACL Injury

Deciding who needs surgery and who doesn't after an anterior cruciate ligament tear is a challenge. Some athletes seem to be able to compensate well after ACL injury. They can return to sports at their preinjury level without surgery. These patients are referred to as copers.

Others have ongoing episodes of knee instability. The knee gives-way underneath them during activities. Athletes in this group are called noncopers.

In this study, researchers look to see if age, gender, or mechanism of injury are linked in any way to becoming a coper vs. a noncoper. The mechanism of injury was either contact or noncontact ACL injury.

Contact injuries occurred when there was a collision with another player or object. Noncontact injuries were more likely to occur when the athlete was pivoting, cutting, or jumping.

A series of tests and measures were used to screen for knee instability after ACL rupture. The screening exam included range of motion, strength, and the single-leg hop test. Patients also reported the number of times they had giving-way episodes. All participants in the study completed a survey of knee function.

Analysis of the results showed that women were more likely to be in the noncopers group. Athletes who had a noncontact ACL injury were also noncopers. Copers seem to have better neuromuscular control. In other words, the muscles around the knee functioned in such a way as to prevent knee instability.

The authors suggest that athletes with altered or poor neuromuscular control may be at risk for ACL injury. If the muscle responds too slowly or without enough muscle fibers contracting, injury may occur.

For noncontact injuries, the ligament ruptures when internal forces are greater than the strength of the ligament. In the case of contact injuries, external force (colliding with another person or object) exceeds the tensile strength of the ligament.

Female athletes tend to produce less muscle stiffness compared to male athletes. Women start to contract and use the quadriceps muscle (along the front of the thigh) before the hamstring muscle (along the back of the thigh). The delayed hamstring response to stress on the ACL may be an important factor in the gender differences.

It was expected that more ACL injuries would occur with increasing age. This was not the case in this study. The mid-range age group (35-44 years old) had the highest rate of injuries. Adults older than 44 had the lowest rate of injury.

As this study showed, there are specific patient groups who are more likely to need surgery after ACL. Females and all individuals who had a noncontact injury describe the noncoper group. Age may be an important variable but more study is needed to understand the role of this factor.



References: Wendy J. Hurd, PT, PhD, SCS, et al. Influence of Age, Gender, and Injury Mechanism on the Development of Dynamic Knee Stability After Acute ACL Rupture. In Journal of Orthopaedic & Sports Physical Therapy. February 2008. Vol. 38. No. 2. Pp. 36-41.