• Bone Density & Structure Disorders Clinical Trials
• Shoulder & Elbow Conditions

• Orthopaedics
• Bone Density & Structure Disorders
• Orthopaedics Clinical Trials
• Shoulder & Elbow Conditions

Glenoid bone deficiency has been implicated as a significant risk factor for failure after arthroscopic stabilization, with data suggesting that 20% to 25% glenoid loss is a “critical level” at which this risk increases [Boileau P et al. J Bone Joint Surg Am 2006; Boileau P et al. Clin Orthop Relat Res 2014]. However, there is a paucity of data available to indicate whether a lesser degree of bone loss results in better arthroscopic outcomes.

John Tokish, MD, Tripler Army Medical Center, Hickam AFB, Hawaii, described his group's study to examine whether glenoid bone loss below “critical” levels would affect redislocation and functional outcomes following arthroscopic repair. Data were obtained from an ongoing quality improvement program at Tripler Army Medical Center and included 72 military personnel who underwent isolated anterior Bankart repairs from June 2009 to September 2011 without having undergone concomitant procedures or having extended labral pathology. The study included 68 men and 4 women with an average age of 26.3 years.

Objective data used for evaluation included demographics, operative information with the number of anchors used, and advanced imaging estimates of bone loss. Subjective data included scores on the Western Ontario Shoulder Index (WOSI) and the Single Assessment Numeric Evaluation (SANE), as well as patient-reported dislocations. A minimally clinically important difference on the WOSI was set at 220; a successful WOSI score was considered to be in the range of 320 to 420.

Glenoid bone loss was established with the “perfect circle technique.” A perfect circle was drawn on a sagittal cut of the en fos glenoid. A line was drawn across the glenoid at the level of the bony defect. A separate line was drawn from the anterior lip of the glenoid to the anterior edge of the perfect circle. The lines were divided and converted to a percentage of the glenoid that was absent. Two such determinations were made by 4 independent viewers at a minimum of 2-week intervals.

Cases were divided into quartiles stratified by bone loss; recurrence rates and outcomes were then compared by quartiles. The researchers also analyzed those cases where bone loss resulted in increased recurrence without a significant increase in WOSI scores. If redislocation was excluded, the analysis was repeated to determine if stable patients had worse outcomes with increasing bone loss independent of recurrence.

Overall, average bone loss was 13.4%. Bone loss over the 4 quartiles increased from 0% to 35%, and the recurrence rate increased more than 2-fold from quartile 1 to quartile 4. WOSI scores worsened with each quartile (Table 1). When patients with recurrence (n = 7) were compared to those without (n = 64), bone loss and WOSI scores were twice as high. When patients with recurring dislocations were excluded from the analysis, bone loss still predicted outcomes. The WOSI score was significantly higher (p = .03) in patients with bone loss > 13.5%—well below the “critical level” cutoff of 20% to 25% currently used to predict failure following arthroscopy (Table 2).

Dr. Tokish addressed several study limitations, including its retrospective design and the lack of preinjury scores. Limitations aside, however, he encouraged clinicians to reconsider the cutoff for “critical bone loss” because of its impact on recurrence rates and functional outcomes.

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