ACCURACY OF RADIALLY RECONSTRUCTED MAGNETIC RESONANCE ARTHROGRAPHY IN DIAGNOSING ACETABULAR LABRAL TEARS AND CARTILAGE DEFECTS

Abstract

Background: Acetabular labral tears are increasingly recognised as a cause of hip pain in young adults and middle aged patients. Degenerative acetabular conditions and sporting activities can cause labral injury. Recent interest has focussed on anterior femoroacetabular impingement as a cause of labral injury, progressive articular cartilage damage and secondary osteoarthritis. Labral tears are difficult to diagnose clinically or with conventional radiographic techniques.

Aim: The purpose of this study was to assess the accuracy of MR arthrography in locating labral tears and articular cartilage defects compared with hip arthroscopy.

Materials and Methods: 200 consecutive patients with a diagnosis of acetabular labral tear underwent hip arthroscopy. All of them had a preoperative Magnetic Resonance Arthrogram done by a single musculoskeletal radiologist using a standard protocol. The labrum was assessed for abnormalities of morphology and signal intensity. Acetabular articular cartilage defects were expressed as a reduction in joint space. All hip arthroscopies were done by a single surgeon after a trial period of conservative therapy consisting of activity modification, physiotherapy and non-steroidal anti-inflammatory medications. All procedures were recorded digitally and documented in an operative report. Labral tears and acetabular cartilage abnormalities were described by location and appearance.

Results: Comparison of MRA and hip arthroscopy findings demonstrate MRA to have a sensitivity of 100%, positive predictive value of 99%, negative predictive value of 100% and accuracy of 99% in predicting labral tears. MRA correctly identified the location of labral tears in 90% of cases. Acetabular cartilage abnormalities were under recognised by MRA (43 hips on MRA vs 54 hips on arthroscopy). MRA was not sensitive enough to pick up early delamination of cartilage adjacent to labral tear in 6 hips.

Conclusion: Hip MRA with radial reformatting has high accuracy rates in diagnosing and localising hip labral lesions.