2017 ISAKOS Biennial Congress ePoster #1032
Normal Variation of Rotatory Knee Laxity in Athletes
Thomas R. Pfeiffer, MD, Cologne, NRW GERMANY
Ajay C. Kanakamedala, MD, Pittsburgh, PA UNITED STATES
Elmar Herbst, MD, PhD, Münster GERMANY
Kanto Nagai, MD, PhD, Kobe, Hyogo JAPAN
Adam Popchak, DPT, PhD, Pittsburgh, PA UNITED STATES
Amir Ata Rahnemai Azar, MD, Pittsburgh, PA UNITED STATES
Conor I. Murphy, MD, Pittsburgh, PA UNITED STATES
Volker Musahl, MD, Pittsburgh, PA UNITED STATES
University of Pittsburgh, Pittsburgh, Pensilvania, UNITED STATES
FDA Status Not Applicable
Healthy subjects have a mean side-to-side difference of 0.6mm of anterior translation of the lateral compartment of the knee during quantitative Pivot Shift test measured by a video-based 2-D image analysis based tablet technology.
Interindividual variations in generalized knee laxity are poorly understood. A subset of patients who are noted to have a pivot shift glide without any injury. However, it is unclear whether increased knee laxity is a risk factor for anterior cruciate ligament (ACL) injuries. Therefore, the purpose of this study was to determine the average anterior translation of the lateral compartment of the knee during a quantitative pivot shift test in a healthy collegiate athlete population. It was hypothesized that increased anterior translation would correlate with generalized ligamentous laxity, knee hyperextension, and increased anterior-posterior tibial translation.
98 healthy division I college athletes (Football, Soccer, Basketball, Baseball, Track and Field) between 18 and 25 years of age with no history of knee injury were tested. Study participants completed the Tegner and Marx Activity Scales, IKDC Subjective Knee Form (IKDC-SKF), and underwent physical examination consisting of ligamentous laxity testing using the rolimeter (Aircast, Europe) and measurement of active and passive ROM with a goniometer. A standardized pivot shift test was performed in both knees and quantified using tablet technology as previously described. Generalized ligamentous laxity was assessed using the Beighton score. Spearman’s rank correlation coefficient was used to analyze correlations. Significance was set at a p-value of < 0.05.
50 female and 48 male athletes with respective median Tegner and Marx scores of 10 (6-10) and 16 (4-16) were enrolled. The mean IKDC was 98.8 (+/-2,6) points and did not correlate significantly with quantitative Pivot Shift values (NS). The average anterior translation of the lateral compartment of the knee during the pivot shift test was found to be 1.6mm (0.1-7.1) and 1.7mm (0.3-5.7) for the right and left knees, respectively, with a mean side-to-side difference of 0.6mm (+/-0,7). Anterior translation of the lateral compartment of the knee during the pivot shift test was significantly higher in female (1.8/1.8 mm) than in male (1.3/1.6 mm) participants (p<0.05). There was a significant correlation between quantitative pivot shift values and anterior tibial translation as measured by the rolimeter (9.0 mm ±3,4; rho=0,34 p < 0.05). The median Beighton score was found to be 0 (range 0-5), indicating that no subject in this population had generalized ligamentous hyperlaxity. Further, the Beighton score did not correlate with anterior translation of the lateral compartment of the knee.
The main finding from this study is that healthy, competitive athletes have a mean anterior translation of the lateral compartment of the knee during the pivot shift test of 1.6 to 1.7mm. Prior studies on ACL injured patients reported a mean lateral translation of 2.0mm and 3.8mm for subjects with a low-grade and high-grade pivot shift, respectively. No correlation was found between knee laxity and patient-reported knee scores. This suggests that variation in knee laxity may not significantly affect knee-related function and quality of life of athletes. In the future, the data from this study might be helpful for clinicians when evaluating side-to-side differences in athletes with a possible ACL injury.