The prevalence of abnormal magnetic resonance imaging findings in asymptomatic knees. With correlation of magnetic resonance imaging to arthroscopic findings in symptomatic knees.

The purpose of this study was to prospectively evaluate the prevalence of abnormal magnetic resonance imaging scans of the knees of asymptomatic subjects. A prospective analysis of magnetic resonance imaging to arthroscopic findings in symptomatic knees was also performed. The prevalence of meniscal tears found in asymptomatic knees was 5.6% (medial meniscus, 1.9%; lateral meniscus, 3.7%). Other abnormal findings included a prevalence of 1.9% for degenerative changes of the medial femoral condyle and 3.7% both for ganglion cysts and patellofemoral joint articular cartilage degenerative changes. There was also a prevalence of 24.1% of Grade II signal changes of the posterior horn of the medial meniscus. Statistical comparison of our results to previous studies revealed that the magnetic resonance imaging scan readings on the asymptomatic knees in this study were accurate and lesions were correctly identified. We recommend that clinicians match clinical signs and symptoms with magnetic resonance imaging findings before instituting surgical treatment because of a 5.6% prevalence of meniscal tears in the asymptomatic population. The significance of the high percentage of posterior horn medial meniscal Grade II signal changes is unknown.

Arthroscopic decompression of shoulder impingement secondary to Os acromiale.

Os acromiale is the result of failure of one of the outer ossification centers of the acromion to unite with the more medial portion. This creates an additional motion segment which may itself contribute to impingement syndrome of the shoulder or which may create hypertrophy or spurs which directly impinge on the cuff. Three cases of impingement syndrome of the shoulder with associated os acromiale are presented. All three were initially relieved with arthroscopic subacromial decompression of either the entire os acromiale or simply of the impinging spur. After 1 year, however, all three had recurrent or continued complaints of pain and/or impingement. Therefore, it would appear that arthroscopic subacromial decompression is not a solution to impingement syndrome secondary to os acromiale. Careful preoperative radiographic evaluation to rule out all causes of impingement syndrome including os acromiale is essential so that the surgeon may better choose an approach to decompression.