Summary
HSI >/= 15mm was associated with a 50% failure rate following adolescent arthroscopic bankart repair, yet off-track lesions were not predictive of failure.
Abstract
Introduction
The treatment of adolescent shoulder instability can be a challenging problem, with multiple patient and radiographic risk factors for recurrent instability. Although glenoid bone loss has been well described, humeral bone loss has gained more recent attention, particularly with respect to “off-track” lesions. The purpose of this study is to evaluate clinical and radiographic predictors of failure following arthroscopic bankart repair in adolescents.
Methods
A retrospective IRB approved study was performed to identify patients less than 19 years of age treated with isolated arthroscopic anterior labral repair for unidirectional shoulder instability. Radiographic measurements of glenoid diameter, % glenoid bone loss, glenoid track, Hill-Sachs interval (HSI), HS/glenoid track (HS/GT) ratio, and hill-sachs depth were performed for all patients with magnetic resonance imaging (MRI). All patients were contacted at final follow-up to collect outcome scores (PASS and SANE scores, activity level). All patients had minimum 24-month follow-up. Failure was defined as revision surgery or post-operative subjective instability.
Results
59 patients, 46 males and 13 females with a median age of 16 years [15, 17] were included. 10 patients (17%) had revision surgery and 8 patients (14%) had subjective instability without revision. In univariate analysis, patient height was the only patient factor which was significantly different between the revision/instability (RI) cohort and the non-revision/instability (NRI) cohort.
Intra- and inter-rater reliability (ICCs) for radiographic measurements were good to excellent for all measurements. The only radiographic variable which was statistically significantly different between the RI and NRI cohorts was glenoid diameter. Percent glenoid bone loss, glenoid track, HSI, and HS/GT ratio, were no different. 5 patients measured "off track" with a HSI:GT >1, but this was not associated with RI.
Subgroup analysis of 38 patients with a hill-sachs defect identified significantly greater HSI and HS depth in the revision surgery cohort (20.9mm, 6.8mm respectively) as compared to no revision (13.9mm, 5.0mm respectively), (p=0.001, p=0.031 respectively). Among patients with a HSI >/= 15mm, there was a 50% rate of revision surgery.
Patient reported outcome measures were obtained in all patients PASS and SANE scores at final follow-up were significantly lower in the RI cohort (75.5 and 67.5, respectively) as compared to the NRI cohort (98 and 98 respectively), p<0.001. 74% of NRI patients returned to the same or higher level of sport following surgery, as compared to 56% of RI patients, but this did not reach statistical significance (p=0.225).
Conclusions
31% of adolescent patients in our cohort had revision instability surgery or reported subjective feelings of instability following arthroscopic bankart repair. This was associated with inferior PASS and SANE scores and lower rates of return to sports. Off-track lesions, as measured by HS/GT ratio, were identified in 8.5% of our cohort, but were not predictive of failure with primary bankart repair. Among patients with a HS defect, greater HSI and HS depth was associated with revision surgery. This study includes the highest risk patient population for recurrent instability based on prior studies – male, adolescent, contact sport athlete – and this likely is a confounding factor in identifying additional clinical and radiographic predictors of failure. In our adolescent series, the current definition of “off-track” does not appear to reliably predict failure with isolated bankart repair.