Shoulder MRI after surgical treatment of instability

To analyze magnetic resonance imaging (MRI) findings of the shoulder after an instability operation.

Physical examinations, radiographs and MRI of 10 patients after anterior glenoid bone block insertion for ventral instability were compared. MRI included T1-weighted spin-echo (TR = 600, TE = 20 ms) and T2*-weighted gradient-echo sequences (TE = 600, TE = 18, Flip = 30 degrees) in the axial, oblique-coronal and oblique-sagittal planes.

No patient suffered from recurrent subluxation. We found fusion of the bone block with the anterior glenoid in seven cases, dislocation of the bone block without contact to the glenoid in one case, and no visible bone block in two cases. On MRI, the bone block showed either signal intensity equivalent to fatty bone marrow (n = 4) or was devoid of signal consistent with cortical bone or bone sclerosis (n = 4). In all patients, a low signal intensity mass, 2-4 cm in diameter, was visible next to the glenoid insertion site.

Insertion of a bone block onto the anterior glenoid induces formation of scar tissue, increasing the stability of the shoulder joint. This scar is well visible on MRI and forms independently of the behavior of the bone block itself. MRI is ideally suited for evaluating postoperative shoulder joints after bone-grafting procedures.