Correlation Between a 3-Step MRI Assessment and Surgical Findings in Classifying Pyramidalis–Anterior Pubic Ligament–Adductor Longus Complex (PLAC) Injuries in 161 Athletes: Validation of Application of the PLAC Classification System

Abstract

Background: Adductor avulsions are complex injuries often involving multiple structures, as indicated by several magnetic resonance imaging (MRI) studies. However, no studies have compared MRI assessments using a dedicated groin protocol with surgical findings. Hypothesis: It was hypothesized that MRI assessments using a dedicated groin protocol would correlate closely with surgical findings, applicable to both experienced and novice users of the pyramidalis–anterior pubic ligament–adductor longus complex (PLAC) classification. Study Design: Case series; Level of evidence, 4. Methods: This retrospective study analyzed 161 athletes who underwent MRI using a dedicated groin protocol, followed by surgical repair of the PLAC. Two musculoskeletal radiologists—1 experienced (rater A) and 1 inexperienced (rater B) in the use of the PLAC classification—independently assessed the MRI scans twice, 6 weeks apart, using a structured 3-step protocol to evaluate (1) adductor longus fibrocartilage (intact, partially avulsed, or completely avulsed), (2) pyramidalis separation from adductor longus (intact, partially separated, or completely separated), and (3) pectineus status (intact or partially avulsed). Agreement between MRI and surgical findings was evaluated using a PLAC injury classification (types 1-5), with intra- and interobserver reliability measured by Cohen kappa. Results: Among the 161 athletes, 93 played soccer, of whom 69 were professional. All athletes exhibited complete fibrocartilage avulsion, with 83 athletes (52%) showing adductor longus separation from the pyramidalis. Isolated adductor longus avulsions (PLAC type 1) were observed in only 36 athletes (22%). The interobserver kappa score between MRI assessments and surgical findings was 0.942 for rater A and 0.858 for rater B. Intraobserver ratings were 0.967 for rater A and 0.875 for rater B. Both inter- and intraobserver scores indicated almost perfect agreement. In combination, these statistical findings support the validity, reliability, and applicability of the MRI protocol using the PLAC classification system for 2 users with varying levels of experience. Conclusion: Adductor avulsions were rarely isolated, typically involving multiple muscles. The PLAC classification effectively captured the complexity of these injuries. When used in conjunction with a dedicated MRI protocol, the PLAC classification demonstrated almost perfect agreement and concordance with surgical findings. Together, the PLAC classification and MRI protocol offered a more comprehensive and accurate representation of patients’ clinical and radiological features and provided valuable guidance for surgical planning