Summary

At the time of return to sport after anterior cruciate ligament reconstruction, jump landing mechanics, as indicated by Landing Error Scoring System score, does not seem to be impacted by the initial mechanism of injury.

Abstract

Introduction

Many anterior cruciate ligament (ACL) injuries occur through a noncontact mechanism of injury where the patient is injured during deceleration, pivoting or jump landing. To regain stability in the knee and allow the athlete to return to sport the most common treatment is surgical reconstruction (ACLR) however, there is a lengthy recovery process and a 15% secondary ACL injury rate. Poor jump landing mechanics are a common cause for noncontact ACL injury and are also a risk factor for secondary ACL injury. Therefore, addressing poor jump landing mechanics, especially in those who sustained a noncontact injury, is an important part of the rehabilitation process and decision to return to physical activity participation.

Purpose

To determine if the initial ACL mechanism of injury is associated with the patient's jump landing performance during a return to activity assessment.

Methods

One-hundred and six patients (54M/52F, 21.4±7.8yr, 171.8±11.0cm, 74.4±14.8kg, 9.1±3.2mo post-ACLR) participated in the observational study after a primary, isolated, and uncomplicated ACLR. Each patient self-reported their mechanism of injury as either contact or noncontact. The participant completed the Landing Error Scoring System (LESS) test which was recorded from a frontal and sagittal view then manually scored used Kinovea. A passing score for LESS was a score of four or below. A Chi-Square test was used to compare mechanism of injury and LESS pass/fail criteria. Independent samples t tests were used to compare LESS scores between groups. Tests were considered statistically significant if p < 0.05.

Results

45% (48/106) of participants failed the LESS test. Of those that failed, 69% (40/58) had sustained a noncontact injury and 31% (18/58) had a contact injury. There was no statistically significant difference in mechanism of injury between participants who passed the LESS test and those who failed (X^2=0.47, p=0.49). There was no significant difference for total LESS score between the non-contact group (4.58±2.07) versus the contact group (4.13±2.08, p=0.33). There was no significant difference for frontal LESS score between the non-contact group (2.80±1.52) and the contact group (2.60±1.55, p=0.54), or for sagittal LESS score between the non-contact group (1.78±1.41) and the contact group (1.53±1.33, p=0.41).

Conclusion

Mechanism of initial ACL injury does not appear to impact LESS scores when the patient is being cleared to return to play. Therefore, patients with contact and noncontact injuries display similar landing mechanics following injury indicating that post-surgical landing mechanics may be unrelated to mechanism of ACL injury. There were patients that scored greater than a four for their overall LESS score, which has been associated with an increased risk for reinjury. The decision to allow a patient to return to play should occur after all risk factors, including jump landing mechanics, have been properly mitigated during rehabilitation.