Can the distal tibial insertion of the anterolateral ligament be palpated to identify lesions in anterior cruciate ligament tears?

BACKGROUND: It has been established that the anterolateral ligament (ALL) plays a role in controlling the rotational stability of the knee. We have demonstrated that ALL injuries can be identified by ultrasound. In most instances, the injury is tibial. The objective of this study was to evaluate the correlation between acutely painful palpation of the distal insertion of the ALL and the lesion as observed on ultrasound. METHODS: We conducted a prospective single center study with 130 patients (89 men and 41 women). The mean age was 27.2 ± 8.3 years and the subjects had unilateral ACL injury for less than one month. On average, the distal insertion was palpated 8.8 ± 3.2 days after the trauma to determine the pain status of the ALL. An ultrasound was performed preoperatively by a surgeon trained in ultrasound diagnosis. All assessments were conducted in a double blind method (the surgeon did not know the clinical status of the ALL). We measured the correlation between the ALL ultrasound injury assessment and pain on palpation of the distal insertion using the intra-class correlation coefficient with a 95% confidence interval. The correlation between the preoperative pivot shift grade in the operating room and the ultrasound injury assessment was also examined. This study was approved by the ethics committee. Considering that the objective could not be quantified, the number of subjects required was determined by recruitment for 1 year. RESULTS: The consistency between painful palpation of the distal insertion of the ALL and the ultrasound injury assessment was good with a 95% confidence interval of the ICC at 0.801 (95% CI: 0.730, 0.855) The sensitivity of this clinical test was 92% (95% CI: 88-97), specificity, 88 (95% CI: 82-93), the positive predictive value, 88% (95% CI: 82-94) and the negative predictive value, 92% (95% CI: 87 -97). The consistency between the pivot shift grade in the operating room and the injury on ultrasound was good, ICC = 0.850 (95% CI: 0.794, 0.891) CONCLUSION: The diagnostic value of painful palpation of the distal insertion of the ALL in identifying ALL injury was excellent. This structure is involved in the rotational stability of the knee. Therefore, assessment by palpation is adapted to the specific management of knee trauma.