Multichannel computed tomography (MCCT) analysis of glenoid erosion in shoulder hemiarthroplasty: preliminary clinical applications

Abstract

Glenoid wear following shoulder hemiarthroplasty (HA) has been reported around 80% in long-term follow-up studies. Radiographic analysis is useful to depict glenoid erosion but does not evaluate accurately glenoid bone loss. Multichannel computed tomography (MCCT) allows scanning with submillimeter section thickness through dense areas of glenoid bone, despite the presence of metallic prostheses. In this preliminary study, we performed a MCCT analysis of glenoid erosion, in 15 patients with painful shoulder HA, at an average follow-up of 5.5 years. Clinical scores were retrospectively assessed at an early (1 year), medium (2.5 years), and late (5.5 years) follow-up. We analyzed the following glenoid features: articular line space (ALS), glenoid length (bone stock), glenoid version, morphology of erosion (concentric, superior ed inferior tilt), and gross bone defects. Glenoid was retroversed in 13 patients (minimum 0 degrees maximum 8 degrees), antiversed in 2 patients (2 degrees and 6 degrees). Erosion was described as concentric in 13 patients, eccentric ("superior tilt") in 1 patient, biconcave in another patient. The mean glenoid length was 19.7 mm (min 16.4 max 22.7). Gross bone defects were described in six patients. The scores registered at latest follow-up showed a significant decrease compared with the values at 1 year (P < 0.001) and at 2.5 years (P < 0.001). The patients with glenoid erosion associated with gross defects and ALS <or=1.2 mm had lower scores for pain and lower scores for ROM (P < 0.01). Multidetector CT analysis establishes a new frontier in the postoperative management of shoulder arthroplasty, and its application in the glenoid analysis offers a significant contribution for the following reasons: qualitative and quantitative glenoid features are better seen because volume-rendering eliminates most streak artifacts and produces high-quality images; spatial information relative to the prosthetic devices and the relationship among hardware and bone can be better demonstrated; allows an accurate preoperative planning prior to starting with revision surgery.