Summary

An international multicenter study indicating a correlation between the Beighton hypermobility score and quantitative rotatory knee laxity in healthy knees.

Abstract

Background

Generalized joint laxity is regarded as a risk factor for sustaining anterior cruciate ligament (ACL) injury. However, knee kinematics in patients with generalized joint laxity is not sufficiently understood.

Hypothesis

An increased level of quantitative rotatory knee laxity is associated with a greater level of generalized joint laxity and with knee hyperextension.

Study design: Prospective cohort study; level of evidence, 2

Methods

A total of 103 patients were enrolled across four international centers to undergo anatomic ACL reconstruction. Rotatory knee laxity was evaluated preoperatively, both in the awake state and under anesthesia, using the standardized pivot-shift test. Two devices were used to quantify rotatory knee laxity; an inertial sensor, measuring joint acceleration, and an image analysis system, measuring the lateral compartment translation of the tibia. The presence of generalized joint laxity was determined using the Beighton Hypermobility Score. The correlation between the level of generalized joint laxity and the magnitude of rotatory knee laxity was calculated for the involved knee, the non-involved knee and the side-to-side difference. Further, patients were dichotomized into low (0-4) or high (5-9) Beighton Score groups. Knee hyperextension was determined using a goniometer. When assessing knee hyperextension patients were dichotomized into subgroups (extension = 4° vs hyperextension = 5°). Alfa was set at .05.

Results

Ninety-six patients had complete datasets, 83 and 13 in the low and high Beighton Score groups respectively. There was a significant correlation in anaesthetized patients between the degree of Beighton Score and quantitative pivot shift when analyzing the non-involved knee using the image analysis system (r = .235, p=0.024). No other correlation using the image analysis system and no correlation utilizing the inertial sensor was significant. When analyzing the dichotomized subgroups, no significant correlations could be established for generalized joint laxity or knee hyperextension.

Conclusion

The findings of this study suggest a possible correlation between generalized joint laxity and the contralateral healthy knee indicating a higher degree of rotatory knee laxity in these patients. No correlation was found between generalized joint laxity or knee hyperextension and rotatory knee laxity in the ACL-injured knee.

Clinical Relevance: Individuals with generalized joint laxity might consider prophylactic physiotherapeutic programs. However, future research is needed to better understand if generalized joint laxity could lead to graft failure, inferior post-operative knee function or contralateral ACL injury.