The Relationship between Arthroscopically Definied Acetabular Cartilage Defects and Preoperative Dgemric Indices: Refining the Use of Dgemric

Background: dGEMRIC is an advanced imaging technique that may detect early chondral damage. Although dGEMRIC may be useful in diagnosing early arthritis, there is a paucity of literature correlating local chondral damage with dGEMRIC indices.

Purpose: To report associations between dGEMRIC indices and intraoperatively defined acetabular cartilage damage in non-arthritic hips with femoro-acetabular impingement and/or labral tears, and to evaluate a new dGEMRIC index that may improve utility in predicting the aforementioned chondral defects.

Methods: Between April 2010 and August 2015, 195 hips (183 patients) underwent hip arthroscopy after undergoing dGEMRIC. Exclusion criteria were previous hip conditions or surgeries, arthritis of >1 Tönnis grade, >180 days between MRI and surgery, and missing sagittal superior dGEMRIC index. dGEMRIC indices measured using four methods, one of which was newly formulated to potentially detect coronal anterolateral (CAL) acetabular damage, were compared to arthroscopically-defined cartilage damage (ALAD and Outerbridge classifications). dGEMRIC indices were compared between non-arthritic hips with no/mild (grades 0 and 1) and those with moderate/severe localized chondral damage (grades 2, 3, and 4).

Results: The three established dGEMRIC indices (sagittal superior, coronal superior, and sagittal anterosuperior) were not significantly different when comparing no/mild to moderate/severe localized chondral damage and demonstrated weak correlations to acetabular cartilage damage. The CAL indices demonstrated a significant difference between no/mild and moderate/severe localized chondral damage, according to both ALAD (p < 0.0001) and Outerbridge (p < 0.0001) groups, and was moderately correlated to ALAD (ρ = -0.403; p < 0.0001) and Outerbridge (ρ = -0.454; p < 0.0001) grades.

Conclusions: The three established dGEMRIC indices did not accurately predict the intraoperative acetabular localized chondral damage in non-arthritic hips. The CAL index was the only method able to differentiate between local non/mildly and moderately/severely chondral damage in non-arthritic hips, and was also moderately correlated with these findings.