2017 ISAKOS Biennial Congress ePoster #1116

 

The Incidence of Proximal Avulsion Anterior Cruciate Ligament Tears: A Magnetic Resonance Imaging Evaluation

Jelle P. van der List, MD, PhD, Amsterdam NETHERLANDS
Douglas Mintz, MD, New York, NY UNITED STATES
Gregory S. Difelice, MD, New York, NY UNITED STATES

Hospital for Special Surgery, New York, NY, UNITED STATES

FDA Status Not Applicable

Summary

This study shows that 17% of all acute tears and 35% of acute tears in patients older than 35 years have proximal avulsion ACL (type I) tears, which provides more information on the incidence of tears that could be candidates for arthroscopic primary ACL repair.

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Abstract

Introduction

In the 1970s and 1980s, surgical treatment options of anterior cruciate ligament (ACL) injuries included open primary repair, augmented repair and reconstruction. In 1991, Sherman et al. assessed the role of tear location on open primary repair outcomes and noted that proximal avulsion tears (type I) were associated with better outcomes than midsubstance tears (type IV). Despite these findings, primary repair and augmented repair were abandoned in the surgical treatment algorithm of ACL injuries.

Recently, there has been a resurgence of interest in arthroscopic primary repair of type I tears. Furthermore, augmented repair has been suggested for type II tears, remnant tensioning for type III-IV tears and remnant preservation for type IV-VI tears. The incidence of these tear types is, however, unknown. Therefore, we aim to assess the incidence of the tear types in acute tears using a modified Sherman classification.

Methods

A retrospective search in an institutional radiographic database was performed for knee MRIs at the institution between June 2014 and June 2016. Chronic tears (>1 month between injury and MRI), partial tears and children (<18.0 years) were excluded. Tear locations were graded as proximal avulsion (type I), proximal third (type II), junction proximal third and middle third (type III), middle third (type IV), junction middle third and distal third (type V), distal third (VI) and distal avulsion (type VII). A radiologist, orthopaedic surgeon and research fellow assessed the tear location of 30 patients for the interobserver reliability and the research fellow assessed the tear location in all patients. Interobserver reliability was measured using Cohen’s kappa and graded using Landis and Koch guidelines. Descriptive statistics were used to assess the incidence of the tear types.

Results

A total of 356 patients (57% men) could be included with a mean age of 37.1 years (range: 18.1–81.2 years) and mean delay from injury to MRI of 8 days (range: 0–30 days). Mean interrater reliability of the three observers was ‘substantial’ with Kappa of 0.672 (range 0.599–0.733).

Incidence of type I tears was 17.1% (all soft tissue avulsion), type II tears 25.3%, type III 25.3%, type IV 27.2%, type V 1.4%, type VI 0.6%, and type VII 3.1% (2.5% bony avulsion, 0.6% soft tissue avulsion). Type I tears were common in patients older than 35 (24.7%) and less common in patients younger than 35 (8.8%). There was a trend of more type I tears in females (20.8%) when compared to males (14.4%, p=0.110) and in skiing injuries (21.4%) when compared to basketball (14.3%) and soccer (15.9%).

Conclusions

The modified Sherman classification is reliable in assessing the tear location in acute ACL injuries. Type I tears are noted on MRI in 17% of adult patients with acute ACL tears and in 25% of patients older than 35 years. Furthermore, there is a trend of higher incidence of type I tears in females and patients with skiing injuries. These numbers indicate that in a substantial number of patients have tear types for which arthroscopic primary ACL repair could be considered.