Original article
Internal impingement in the etiology of rotator cuff tendinosis revisited

https://doi.org/10.1016/S0749-8063(03)00732-1Get rights and content

Abstract

Purpose: The theory of internal impingement holds that, in overhead athletes, repeated contact between the undersurface of the rotator cuff and the posterosuperior glenoid rim leads to articular-sided partial-thickness rotator cuff tears and superior labral lesions. However, we have noted this same constellation of lesions in our general patient population. These recreational athletic patients do not routinely assume the position of extreme abduction and external rotation, and thus are unlikely to experience significant internal impingement forces. The goal of this study was to document the prevalence of superior labral lesions in patients being treated for partial-thickness undersurface rotator cuff tears. Type of Study: Retrospective case series. Methods: We retrospectively reviewed the records of 75 shoulders arthroscopically treated for partial-thickness articular-sided rotator cuff tears. With the exception of one professional tennis player, no patients were playing sports at a professional or major college level. No professional or collegiate throwing athletes were included. The prevalence of these lesions and their association with recreational athletics was noted. Results: We found that 55 of 75 (73.3%) shoulders with articular-sided partial-thickness rotator cuff tears also had superior labral lesions. A statistically significant increased prevalence of superior labral lesions in the dominant shoulder was seen (P = .03). In addition, our patients who engaged in overhand throwing had significantly fewer superior labral lesions in the dominant shoulders than did nonthrowers (P = .017). Conclusions: The “kissing lesions” of undersurface rotator cuff tears and posterosuperior labral damage may be explained by mechanisms other than “internal impingement.”

Section snippets

Methods

We retrospectively reviewed the records of 75 shoulders in 72 patients (3 bilateral) with arthroscopically proven partial-thickness articular-sided rotator cuff tears to determine the prevalence of superior labral lesions. These shoulders were part of a series of 79 shoulders previously reported.7 One of the 4 patients not included had an isolated bursal-sided partial-thickness rotator cuff tear (he also had no superior labral lesion). The other 3 were excluded because of incomplete records.

Results

Fifty-one shoulders (68.0%) had the articular-sided partial-thickness rotator cuff tears isolated to the supraspinatus, 21 shoulders (28%) had partial-thickness tears involving the supraspinatus and infraspinatus, 2 shoulders had tendinosis isolated to the infraspinatus, and 1 shoulder had tendinosis of the supraspinatus and subscapularis. Overall, 73 of 75 (97.3%) shoulders had involvement of the supraspinatus.

Fifty-five of 75 (73.3%) shoulders with articular-sided tears had type I labral

Discussion

In this study, 55 of 75 (73.3%) patients from a general, recreational athletic population were found to have superior labral fraying associated with undersurface partial-thickness rotator cuff tears. Others have previously commented on the high prevalence of superior labral fraying in combination with articular-sided rotator cuff pathology. Altchek et al.9 noted a 40% incidence of this combination. Guidi et al.10 noted superior labral degeneration in 90% of patients with partial-thickness

Conclusions

This study documents a high prevalence of superior labral fraying in a general, recreational athletic population with undersurface partial-thickness rotator cuff tears. These lesions occur very frequently in patients who do not routinely engage in overhead athletics and, therefore, may be caused by mechanisms other than internal impingement. They may be better explained by tension overload of the rotator cuff and repetitive superior shearing of the humeral head against the labrum. The proven

Acknowledgements

The authors thank Micheal A. Conditt, Ph.D., for help with the statistical analysis.

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