Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Health and Rehabilitation Sciences

Supervisor

Bryant, Dianne M.

2nd Supervisor

Getgood, Al M.J.

Co-Supervisor

Abstract

Purpose: Graft failure rates following anterior cruciate ligament reconstruction (ACLR) are inadequate in young, active patients. Recently, the STABILITY 1 Study provided level 1 evidence that augmenting hamstring ACLR with a lateral extra-articular tenodesis (LET) reduces graft failure. Further evidence regarding outcomes after LET and in those with specific risk factors is required.

Methods: This thesis includes three studies. In study 1, we used logistic regression to determine predictors of persistent rotatory laxity and graft failure in young, active patients two-years post-ACLR. In study 2, we investigated a subgroup of patients with lateral meniscal posterior root tears (LMPRT) at the time of ACLR to determine how the injury affected their outcome postoperative. In study 3, we performed magnetic resonance imaging on a consecutive subgroup of patients at two-years postoperative to determine whether augmenting ACLR with LET affects articular cartilage quality in the lateral compartment of the knee.

Results: In study 1, adding an LET was significantly associated with 60% lower odds of graft rupture, while younger age, increased tibial slope, high-grade preoperative knee laxity, and earlier RTS were associated with higher odds of graft rupture. Adding an LET and increasing graft diameter significantly reduced persistent rotatory laxity. In study 2, we found that patients with a LMPRT have similar outcomes to patients without LMPRT, regardless of treatment performed. In study 3, we found that T1rho relaxation was slightly elevated in the lateral compartment for the ACLR + LET group. Cartilage relaxation values increased as meniscal tear size increased when the meniscus was excised, while relaxation times were relatively stable after repair.

Conclusion: Our findings confirm the protective nature of the LET while identifying other predictors of clinical failure and graft rupture. Our results suggest clinicians are skilled at deciding when LMPRTs need to be repaired, and that the meniscus should be repaired, where possible, to prevent changes in cartilage relaxation. This study confirms the need for long-term follow-up of STABILITY 1 patients to determine whether the LET provides short-term stability without increasing increased risk of OA development.

Summary for Lay Audience

The anterior cruciate ligament (ACL) is commonly torn in young, active people. ACL tears result in an unstable knee that people cannot trust, so it needs to be replaced with surgery. Adding an extra piece, called a lateral extra-articular tenodesis (LET), to the outside of the knee during ACL surgery leads to a more stable knee and lower chance of injuring the ACL again. This thesis contains three studies using patients from the STABILITY 1 study who underwent ACL surgery with or without LET, to get more information on how patients do after surgery. The goal of the first study is to see which patient and injury characteristics are related to injuring the ACL again after surgery. The second and third projects are magnetic resonance imaging (MRI) studies. MRI lets us see inside the knee to look at damage. The second study takes patients who had a specific injury at the same time as their ACL, called a lateral meniscal posterior root tear (LMPRT), and looks at how the injury was treated and how these patients do after surgery. The last study takes a group of patients from one site to see how adding an LET affects knee cartilage, which protects the knee during activity. When cartilage is injured, it begins to wear down and stops protecting the knee, which can lead to pain and difficulty with activity. MRI can be used to compare cartilage after ACL surgery with or without the LET, to help us think about how these patients will do ten- or twenty-years later. Overall, these studies will help show how specific risk factors relate to results of ACL surgery and whether adding an LET affects knee cartilage.

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