CORRELATION OF THE IMPINGEMENT TEST WITH ARTHROSCOPIC FINDINGS AT THE ACETABULAR RIM IN NONDYSPLASTIC HIPS

Abstract

Aim: The aim of this study was to determine if a correlation exists between the impingement test and the arthroscopic findings at the acetabular rim in non-dysplastic hips. Secondarily, we also wanted to establish if there was a correlation between the pain experienced on the impingement test and the pathology identified.

Patients and Methods: Sixty-two consecutive patients who were due to have an arthroscopy of the hip in our unit were prospectively recruited into the study. All the dysplastic hips were excluded from the study. One observer was involved in examining all the patients and another one in performing all the arthroscopies. The impingement test was considered positive if at 90 degrees of flexion, adduction and internal rotation, the patient complained of discomfort or pain. If the patient experienced pain this was described as a strongly positive test and if there was discomfort experienced it was considered as a weakly positive test. The test was performed on the morning of the arthroscopy and all the intra-articular findings recorded at arthroscopy. A tear of the acetabular labrum and chondral damage in the antero-superior margin of the acetabulum were considered as positive pathology at the acetabular rim.

Results : There were 40 males and 22 females in the study group. The impingement test was positive in 57 patients, strongly positive in 42 and weakly positive in 15. The arthroscopy revealed positive pathology in terms of an acetabular labrum tear and/or chondral damage at the acetabular rim in 55 patients. A negative test was recorded in 5 patients but there was positive rim pathology in two of these 5 patients.

Conclusion: The impingement test correlates positively with the pathology at the acetabular rim; the sensitivity of the test for diagnosing acetabular rim pathology is 96.4 % and the specificity is only 60 % in non-dysplastic hips. However, we did not identify any correlation between the level of pain and the pathology observed.