Basic Science
Glenoid bone resorption after Bankart repair: finite element analysis of postoperative stress distribution of the glenoid

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Background

There are various modifications of the Bankart repair, and postoperative changes to the glenoid morphology after the repair are reported. Among the various procedures performed, a decrease in the lateral glenoid diameter might be related to the surgery that involves removal of the articular cartilage and repair of the labrum–anterior inferior glenohumeral ligament complex on the glenoid surface. This is in contrast to cases without significant bony Bankart lesions that are not on the edge of the glenoid. Thus, this study aimed to compare glenoid rim stress after Bankart repair using 2 methods of finite element analysis: a method of removing the anteroinferior cartilage and repairing the glenohumeral ligament complex on the glenoid and a method of preserving the cartilage and repairing the glenohumeral ligament complex on the glenoid edge.

Methods

Five preoperative computed tomography scans of patients with traumatic anterior instability who underwent arthroscopic Bankart repair were used. Two models simulating different surgical procedures were created as follows: in model G, a 5-mm-thick cartilage on the glenoid rim was removed between 2 and 7 o’clock, and the glenohumeral ligament complex was repaired on the medial edge of the glenoid bone where the cartilage was removed. In model E, the cartilage on the glenoid rim was not removed, and the glenohumeral ligament complex was repaired on the glenoid edge. The load stresses on the anteroinferior area of the glenoid after Bankart repair with models G and E were measured using finite element analysis.

Results

The stress on the glenoid at 3-4 o’clock was 3.16 MPa in model G and 6.42 MPa in model E (P = .043). The stress at 4-5 o’clock was 1.68 MPa in model G and 4.53 MPa in model E (P = .043). The stress at 5-6 o’clock was 2.26 MPa in model G and 3.93 MPa in model E (P = .043).

Conclusion

Significantly lower load stresses were observed at the anteroinferior rim of the glenoid in model G than in model E.

Section snippets

Materials and methods

Five preoperative computed tomographs (CT) from patients with traumatic anterior instability who underwent arthroscopic Bankart repair were used. Preoperative bone defects were less than 10% of the glenoid width in all cases. Amounts of bone loss were measured using the glenoid fossa circle approximation method described by Sugaya et al.25 The subjects included 3 men and 2 women. The mean age at the surgery was 20.2 years (range, 16-26 years).

CT scans were taken with 1.25 mm slice thickness

Results

The stress at 3-4 o’clock was 3.16 MPa in model G and 6.42 MPa in model E (P = .043). The stress at 4-5 o’clock was 1.68 MPa in model G and 4.53 MPa in model E (P = .043). The stress at 5-6 o’clock was 2.26 MPa in model G and 3.93 MPa in model E (P = .043). Model G showed significantly less load stress than model E in all areas.

Since there were only 5 cases, gender and other factors could not be analyzed statistically.

Discussion

The most important finding was significantly lower load stresses at the anteroinferior rim of the glenoid in the model where the cartilage on the glenoid rim was removed between 2 and 7 o’clock and the glenohumeral ligament complex was repaired on the medial edge of the glenoid bone. This finding supports the idea that the decreased lateral diameter of the glenoid width after surgery using the method of removing the articular cartilage was caused by stress shielding.

FEA is widely applied from

Conclusion

Using FEA, load stresses on the anteroinferior area of the glenoid after Bankart repair using a method of removing a 5-mm-thick cartilage on the glenoid rim between 2 and 7 o’clock and repairing the glenohumeral ligament complex on the medial edge of the glenoid bone where the cartilage was removed (model G) and a method of not removing the cartilage of the glenoid rim and repairing the glenohumeral ligament complex on the glenoid edge (model E) were investigated. Significantly lower load

Disclaimer

The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

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