IS INSTRUMENTED LAXITY A RISK FACTOR FOR FUNCTION AND ARTHRTITIS AFTER ACL RECONSTRUCTION : A PROSPECTIVE COHORT AT TWELVE YEARS FOLLOW-UP

KURT P SPINDLER WARREN DUNN RICK PARKER BRYAN HAN FRANK HARRELL CHUCK MATHEWS

Corresponding author Kurt P Spindler

CCF:Sport health Vanderbilt sports medicine

INTRODUCTION

Traditional measures of results for ACL reconstruction have appropriately focused on restoring anterior –posterior laxity (APL) in the development and refinement of commonly utilized arthroscopically assisted techniques performed today. This has resulted in a majority of successful short-term results with return to play and the majority of measurements of less then 3 mm laxity. To conduct studies the primary outcome was laxity with sample sizes to detect 1-2 mm side-to-side differences each group required 60-70 patients . The long-term outcomes focusing on arthritis and functional outcomes of modern arthroscopically assisted techniques with autograft hamstring or patellar tendon require investigation . In addition a multivariate approach for risk factors including meniscus, articular cartilage, and bone bruise on MRI should be evaluated at ten years for arthritis and function. Nine RCT’s comparing autograft choice at two-three year f/u have shown subtle statistically significant differences with little clinical relevance between graft types . One study found that meniscus injury and treatment was the best predictor of patient relevant outcome . A caveat was a multivariable analysis was not performed to control for confounding variables associated with meniscus pathology. A study by Daniel demonstrated a self-selected group of “low demand “ patients left ACL deficient had fewer radiographic arthritis then the group of “higher demand “ having ACL recon . Similarly Wu and Shelbourne retrospectively evaluated ACL reconstructions at average of 5-10 year f/u both studies in univariate analysis observed meniscus loss as result of injury associated with poorer results . Clearly how instrumented laxity , meniscus injury,articular cartilage injury and bone bruises predict the long-term results a ten years requires a multivariable analysis. The results should include arthritis( radiographic ,MRI), WOMAC, present activity level , and function as defined by newly created patient relevant outcome instruments ( KOOS and IKDC ) , and quality of life instrument (SF-36). In addition the correlation between instrumented laxity with return to sports , activity level , or “ function “ have not been widely evaluated. Studies by Wotyjs and Synder-Mack have failed to demonstrate a tight correlation between postoperative or post ACL tear with functional parameters . Perhaps suggesting other intra and extra articular factors are the primary determinant of return to function. Alternatively a threshold for tolerable laxity could exist below which other variables predominate such as meniscus tears , degenerative arthritis or additional surgery post reconstruction could be independent risk factors . If instrumented laxity is appropriately the primary studied outcome variable for ACL reconstruction then not only the threshold but correlation for which laxity determines long-term results of arthritis , activity level, patient relevant outcomes , and functional tests warrants study in a prospective cohort . We hypothesized that bone bruise , meniscus tears , and articular cartilage injuries are associated with degenerative arthritis at long-term follow-up of ACL reconstructions(ref KPS ’93). In addition we hypothesize that instrumented laxity at ten year follow-up is not associated with function ( patient relevant outcomes or activity level ) or arthritis.