Validation of the Ligamentous-Fossa-Foveolar Complex (LFFC) Grading System With Clinical Correlation for Patients Undergoing Hip Arthroscopy.

Abstract

Background: Pathology involving the acetabular fossa is often identified during hip arthroscopy, with many of the descriptive classification systems focusing on the ligamentum teres (LT). Recently, a novel grading system for ligamentous-fossa-foveolar complex (LFFC) lesions was introduced for open hip preservation surgery that included evaluation of the cotyloid fossa and perifoveal cartilage.

Purpose: To validate the LFFC grading system for hip arthroscopy and correlate these results with preoperative and intraoperative findings.

Study design: Cohort study (diagnosis); Level of evidence, 3.

Methods: High-resolution arthroscopic images of the central compartment were obtained identifying the LT, cotyloid fossa, and perifoveal cartilage in a prospective series of patients undergoing hip arthroscopy. Each structure was graded according to increasing pathology on a scale of 0 to 4 based on a modified LFFC classification system to include the pulvinar intra-articular adipose tissue. Five surgeons graded the images, which were then randomized and regraded for intraobserver reliability. Agreement was quantified by the intraclass correlation coefficient (ICC) and kappa (κ) statistic to determine inter- and intraobserver reliability. Grading discrepancies were resolved in conference with the senior author, and final LFFC grades were compared with preoperative clinical and radiographic data as well as intraoperative findings.

Results: A total of 93 patients were included in the study. LFFC component intraobserver reliability for 2 rounds of grading resulted in an LT ICC of 0.78 to 0.90, cotyloid fossa ICC of 0.85 to 0.93, and perifoveal cartilage ICC of 0.78 to 0.87 with an LFFC total score ICC of 0.87 to 0.95. Interobserver reliability resulted in an LT ICC of 0.73 to 0.91, cotyloid fossa ICC of 0.84 to 0.95, perifoveal cartilage ICC of 0.83 to 0.91, and LFFC total score ICC of 0.89 to 0.96. Severe central compartment pathology (LFFC total score >6) was significantly associated with age (48.2 vs 34.4; P = .0002), preoperative Tönnis grade 1 (43% vs 4%; P < .0001), preoperative Tönnis angle (8.7 vs 5.2; P = .002), and intraoperative femoral head weightbearing chondral lesions (14% vs 0%; P = .02) when compared to patients with an LFFC score <6.

Conclusion: The modified LFFC grading system demonstrated satisfactory intraobserver and interobserver reliability for patients undergoing hip arthroscopy that compares favorably with existing arthroscopic classification systems for the acetabular fossa. The addition of a descriptive classification system for the pulvinar intra-articular adipose tissue did not decrease the reliability of the grading system. Increasing LFFC scores were found to be associated with known risk factors for inferior outcomes after hip arthroscopy providing enhanced clinical utility for this grading system.