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Key Difference Between Open Versus Arthroscopic Shoulder Stabilization

This is the first study to directly compare muscle strength after open versus arthroscopic surgery for recurrent shoulder dislocation. Other studies have reported on muscle strength after open surgery OR after arthroscopic surgery -- but never comparing the two.

Results from other studies have been varied. Some showed a loss of strength, others didn't. Strength deficits were observed in both internal and external shoulder rotation after arthroscopic surgical stabilization.

The subscapularis muscle of the rotator cuff is split in two during the open procedure. It has always been suspected that strength would be disrupted more after this approach. In this study, there were changes in strength for both internal and external rotation for both groups. The biggest factor linked to changes in strength was arm dominance.

The researchers tested strength for the surgical side as well as the uninvolved (nonoperative) arm. Strength was tested at different speeds and angles to represent functional tasks. Testing was performed at baseline (before surgery) and one year after surgery.

The results showed that the nonoperative arm was always stronger than the surgical side. This was true even when the dominant arm was operated on. But in general, the greatest loss of strength occurred in the nondominant arm no matter which kind of surgery was done.

The amount of strength deficit was different from patient to patient and varied as much as 20 per cent from one patient to another. Post-operative external rotation was weaker than internal rotation for both groups.

Overall, there was no significant difference in muscle strength one year after open or arthroscopic surgery to stabilize the shoulder. Both groups had loss of strength in rotational motions. Splitting the subscapularis during the open procedure did not seem to make a difference in long-term strength outcomes.

The loss of strength after this procedure suggests a need to review rehab protocols. It may be necessary to revise the rehab approach after shoulder stabilization surgery. Regaining rotational strength is an important goal that must be better addressed.

References: Laurie A. Hiemstra, MD, PhD, FRCS(C), et al. Shoulder Strength After Open Versus Arthroscopic Stabilization. In The American Journal of Sports Medicine. May 2008. Vol. 36. No. 5. Pp. 861-867.

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