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

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

Bone defects on the glenoid or humeral side are a primary reason for failure following instability surgery [Burkhart SS, De Beer JF. Arthroscopy 2000; Bollier MJ, Arciero R. Sports Med Arthrosc 2010]. The critical level for bone loss at the glenoid or humeral head as a risk factor following instability surgery is historically considered to be 20% to 25% and 25%, respectively. According to Robert Arciero, University of Connecticut Health Center, Farmington, Connecticut, USA, however, much of these data are derived from cadavers with isolated lesions, whereas in clinical practice, concomitant defects of the glenoid and humeral head occur in 89% to 100% of patients with instability.

Dr. Arciero shared data from a study that evaluated combined lesions of the shoulder from a cadaveric model that was based on an actual patient database. The purpose of the study was to assess the effects of concomitant glenoid (Bankart) lesions and humeral head (Hill—Sachs) lesions in a bipolar bone loss model.

The study was designed to determine (1) whether combined defects of the glenoid and humeral head had an additive negative effect on stability, and (2) whether the percentage of bone defects that predict instability is lower in the two lesions when they occur concomitantly. The working hypothesis was that combined humeral head and glenoid defects would increase glenohumeral translation and adversely affect soft tissue repair and that lower percentages of bone loss would compromise soft tissue repair.

Using eight cadavers, the research team created 2-, 4-, and 6-mm glenoid bone lesions and an isolated 1.47-cm³ Hill—Sachs lesion. A 3D printer was used to make a model of the proximal humerus with a 1.47-cm³ bone lesion. The humerus lesion was then recreated in cadaveric specimens. Glenoid bone defects were created and made parallel at 2, 4, and 6 mm, which represented an 8% to 25% defect. These bone defects were tested on a test shoulder apparatus at 60° of glenohumeral abduction and 60° of external rotation, and with a 50 Newton compressive load as described by previous research [Itoi E et al. J Bone Joint Surg Am 2000; Yamamoto N et al. Am J Sports Med 2009]. The primary outcome was load to translation to 10 mm, loaded at a rate of 2 mm/second. Every specimen was tested intact with the humeral lesion, with subsequent bony lesions, and with Bankart repair (Table 1).

Dr. Arciero then reviewed the results. There was no significant difference in average load to translation when the two lesions were tested separately. When the two lesions were tested together with a 2-, 4-, or 6-mm glenoid defect, however, the average load-to-translation decreased significantly (Figure 1).

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Figure 1.

Cumulative Effects of Bone Defects on Load to Transmission

HS=Hill—Sachs.Reproduced with permission from RA Arciero, MD.

Dr. Arciero concluded that combined lesions have an additive and adverse effect on the amount of bone loss required to compromise soft tissue repair and that the critical point is lower than that of either defect evaluated in isolation. This may require surgeons to investigate alternative surgical procedures other than soft tissue repairs alone.

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