Shoulder dislocations are common in the United States, with an incidence of nearly 24 per 100,000 person-years. For athletes younger than age 30, the risk of repeat dislocations ranges from 70% to 100%. Each dislocation can cause cumulative damage to the stabilizing structures in the shoulder, including the labrum, glenohumeral ligaments and joint capsule, which increases the risk for future dislocations.
Pinpointing the optimal time for surgical intervention
The gold standard for treating shoulders prone to dislocations is arthroscopic stabilization, but each subsequent dislocation affects the quality of tissue and bone stock that surgeons can utilize. In one 10-year study by Jakobsen et al., patients who had conservative, nonsurgical treatment had dislocation rates of 62%, compared with 9% in surgical patients.
Despite data showing the benefits of early surgical intervention, many patients put off surgery. This increases the risk of future dislocations, which are associated with a higher rate of recurrent shoulder instability after surgical stabilization that may require revision surgery.
“With each dislocation, patients lose about 3% to 4% of bone stock and further attenuation of labral-capsular tissue, and with multiple dislocations before a surgical procedure, patients have a greater risk of failing a more straightforward arthroscopic soft tissue repair of labral-capsular tissue,” says Brian Forsythe, MD, an orthopedic surgeon specializing in arthroscopic shoulder, knee and elbow surgery at Rush. “So the question is, when is the optimal time to intervene to restore stability, and is it reasonable to allow athletes to go back to sports with a shoulder that hasn’t been surgically stabilized?”
The aim and methodology of the study
Dr. Forsythe and his co-authors, including Elyse Berlinberg, Vikranth Mirle, Harsh Patel, Vahram Gamsarian, Joshua Chang and Daanish Khazi-Syed from Rush, set out to determine the degree to which single versus multiple dislocations prior to arthroscopic surgery affect the need for revision surgery. To do so, they extracted data from an all-claims database representing 144 million patients from across the United States from 2010 through 2020. In this matched case-control analysis, patients who had a single instability event were matched in a 1:1 ratio to patients who had multiple dislocations by surgery type (open Bankart repair, anterior bone block, open Latarjet, open capsulorrhaphy or arthroscopic capsulorrhaphy) as well as age and gender. Dr. Forsythe says his team designed this large, well-powered database study so their results would be generalizable to a wide population.
Researchers assessed the rate of revision shoulder instability surgery at least 90 days after initial surgery, as well as rates of closed shoulder reductions, emergency department (ED) visits, readmissions and intensive care unit admissions within 90 days of surgery. They also tracked rates of medical complications, adhesive capsulitis and manipulation under anesthesia.
Results
A total of 322 patients were included in the final matched cohort analysis, with equal numbers of patients with a history of single versus multiple dislocations.
Dr. Forsythe’s team found that the risk of revision surgery following stabilization was 2.75 times higher in patients with multiple dislocations prior to the index surgery. According to Dr. Forsythe, these findings suggest that cumulative damage to the shoulder from multiple dislocations may affect shoulder stability, even after surgical intervention. “Our study clearly illustrates that postponing surgery puts patients at risk for recurrent dislocations and an almost three-times greater risk of failing the stabilization procedure and requiring revision surgery,” Dr. Forsythe says.
Multiple dislocations were also associated with a 3.76 times higher risk for postoperative dislocation requiring a closed reduction. Researchers also found a dose-dependent relationship between the number of dislocations prior to surgery and the rate of postoperative dislocations requiring intervention. Each additional dislocation was associated with a 5% higher risk for closed reduction surgery and a 3% higher risk for revision stabilization surgery.
These findings support previous results from Wasserstein et al., who reported a 7.7% revision rate in patients with more than three dislocations before surgery, compared with a 3% revision rate in those with single dislocations. In addition, Marshall et al. found patients with multiple dislocations before Bankart repair were six times more likely to require revision surgery, compared with patients who had a single dislocation.
In Dr. Forsythe’s study, patients with multiple dislocations were also more than twice as likely to visit the ED within 90 days of surgery. Diagnostic data and procedure codes suggest that postoperative instability requiring closed reduction was likely the cause of these ED visits. However, there was no difference in readmissions between the single and multiple dislocation groups.
Isolated arthroscopic capsulorrhaphy was associated with a seven-fold higher risk of revision surgery for instability. These findings reinforce previous studies suggesting that simply tightening the joint capsule via tissue imbrication is not enough to stabilize the shoulder. “The study shows that it’s absolutely imperative that the labral tissue be repaired concurrently with the capsular imbrication,” Dr. Forsythe says.
Researchers also found a higher risk for revision surgery in patients who had an open Latarjet procedure, which may be related to differences in patient selection, as open shoulder stabilization is more likely to be recommended for patients with multiple dislocations.
Next steps
The next phase of Dr. Forsythe’s research is to explore the effect of interventions performed concurrently with shoulder stabilization, such as the Remplissage procedure to fill the bony defects in the humeral head.
In the meantime, Dr. Forsythe believes his team’s findings will help surgeons better advise young athletes with shoulder instability to not delay surgery to stabilize their shoulder so they can prevent future dislocations, as these can contribute to early arthritis and possibly put an end to patients’ athletic endeavors.
“This study enhances our ability as orthopedic surgeons to practice shared decision-making with patients, using not only data from our own patients but also data from other institutions across the country,” Dr. Forsythe says.
