Correlation of the SLAP lesion with lesions of the medial sheath of the biceps tendon and intra-articular subscapularis tendon.

BACKGROUND: Superior labral anterior to posterior (SLAP) lesions have been well described in the literature and are thought to be secondary to traction injuries to the biceps anchor and/or falls on the outstretched arm. The pulley has recently been described as a structure that aids in the prevention of biceps instability. The intra-articular subscapularis insertion (IASS) has been noted to contribute to the robust nature of the medial sheath. The purpose of the study was to determine a potential correlation of SLAP lesions and pulley lesions with/without IASS lesions, (hereafter referred to as medial sheath) as forces that can disrupt the biceps anchor and may also disrupt structures of the medial sheath or vice-versa.

MATERIALS AND METHODS: Three hundred and sixteen consecutive shoulder arthroscopies performed by one surgeon were reviewed retrospectively. Operative reports and arthroscopic pictures were carefully reviewed with particular attention paid to the labral and pulley pathology. Selection bias was noted as the author had never operated primarily for a Type 1 SLAP lesion. Following, however, and as such, the exclusion criteria, was a Type 1 SLAP.

RESULTS: There were a total of 30 SLAP lesions and a total of 126 medial sheath lesions. There were 13 patients who had both SLAP and medial sheath lesions. There were 17 patients who had a SLAP lesion without a medial sheath lesion. There were 96 medial sheath lesions without a SLAP. A comparison of rates between patients who had a medial sheath lesion with a SLAP and those who had a medial sheath lesion without a SLAP, for the 316 patients, and when tested with a Fisher exact test revealed that there was no statistical significance, P = 0.673. The prevalence of SLAP lesions in this population of 316 patients was 9.4%, Buford 1%, medial sheath lesions 39%, and SLAP and medial sheath lesions 4%. Interestingly, there were three Buford complexes, all associated with a SLAP and one Buford complex was associated with both a SLAP and a pulley. When looking at the rate for medial sheath lesions when restricted to patients with SLAP lesions, the medial sheath lesion rate was 43.3% (13/30; 95% confidence interval 19.6-66.9%). The medial sheath lesion rate for patients with SLAP lesions differs from a rate of zero and is statistically significant, with a P value <0.05. In other words, when a SLAP lesion is present there is a statistically significant rate of medial sheath lesions, a previously unpublished association.

CONCLUSIONS: With a 43% association of the medial sheath lesion with SLAP lesions, the author postulates that forces that affect the biceps anchor may also damage the pulley system of the bicipital sheath and, as such, this anatomic structure should be evaluated, especially when SLAP lesions are present.