Posterior bone block for posterior instability

Case contributed by Dr Domenico Nicoletti

Presentation

Recurrent posterior dislocation

Patient Data

Age: 25 years
Gender: Male

postoperative rx right shoulder

The bone graft is placed in the level of the glenoid joint line. The screw fixation is tricortical.

postoperative Ct right shoulder

Axial CT scan of the shoulder showing the triangular shaped posterior glenoid defect (“delta”-type). Posterior tricortical bone block aligned in place. The angle of glenoid retroversion is increased: 18.5 °. There is os acromiale.

Operative report

Autologous tricortical iliac bone graft for posterior glenoid defect.

 

Case Discussion

There are two different patterns of posterior glenoid deficiency. For traumatic posterior shoulder instability a triangular (“delta”) bony defect has been described in contrast to a rounded posterior glenoid deficiency (“lazy J”), which is mainly found in atraumatic posterior instability. It is essential that the graft be voluminous (up to 3 cm long). A tricortical bone graft is harvested from the ipsilateral anterior iliac crest. The mean glenoid retroversion measured in the MRI scans according to the method described by Friedman et al. is 10.5°.

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