Traumatic dislocation of the shoulder is an injury that commonly affects young athletes and has been associated with recurrent instability despite surgical repair. This recurrent instability leads to long-term disability due to early osteoarthritis and loss of shoulder function. Recently, we have characterized the location, magnitude, and direction of capsular injury following multiple shoulder dislocations. The findings of these studies show that the capsular injury pattern following dislocation occurs at regions not previously addressed during surgery and depends on the number of dislocations. This suggests that a more injury-specific capsular repair might be needed in order to improve shoulder function post-operatively. The overall objective of the proposed project is to assess the restoration of glenohumeral kinematics following multiple dislocations using injury-specific capsular repair strategies. Our overall hypothesis is that capsular plication procedures must account for magnitude and direction of injury to properly restore normal joint stability. The first step to achieve this goal is to develop an optimized design for injury-specific capsular repair based on non-recoverable strain data (capsular injury) that best restores kinematics to those of the intact shoulder.
(Aim 1 a) A novel robotic testing system will dislocate cadaveric shoulders and simulate clinical exams to assess joint stability. An optical tracking system will quantify the non-recoverable strain. In order to translate this information to the clinical setting, the non-recoverable strain data will be correlated with capsular surface area changes as quantified on MR arthrogram.
(Aim 1 b) Finally, MR arthrograms will be used to characterize capsular injury before and after surgical repair in subjects that have dislocated their shoulders. The contralateral shoulder will serve as a control and allow assessment of areas of the capsule that current repair methods do not adequately address (Aim 2). The findings of this study will further validate the need for injury-specific repair strategies and provide a solution that can ultimately be implemented in a future randomized controlled trial. Exploring injury-specific strategies can help improve shoulder function and reduce the rate of recurrent instability following capsular repair. Thus, guidelines could be developed to direct the treatment of athletes that experience multiple dislocations throughout a season. Finally, the cost and disability associated with the long-term sequelae of multiple shoulder dislocations will be reduced.
Dislocation of the shoulder commonly occurs in young athletes and has been associated with a high recurrence rate and decreased function despite surgical repair. The proposed research will help establish clinical guidelines for the use of injury-specific capsular repair strategies based on quantitative measures of capsular injury, rather than the current standard of care which fails to address the full extent of capsular injury due to the reliance on a subjective assessment of capsular injury, which is currently limited in the clinical setting. Thus, results of this study will individualize surgical management to improve shoulder function and reduce the occurrence of disabling long-term outcomes of shoulder dislocations.
