Abstract
The composition and morphology of the glenoid are integral to the support of a glenoid component in total shoulder arthroplasty (TSA). This study was performed to identify the morphology of glenoid cavity in pre and post replacements in a cadaveric model.
Eleven normal cadaveric shoulders (Right – 5, Left – 6) were dissected down to the bone such that the glenoid labrum was left intact. Computerised Tomography (CT) scanning at 0.5 mm thickness was performed on each of the specimens in a standardised fashion to evaluate the morphology of the glenoid and glenoid medullary cavity. CT scanning was repeated after a mixture of cemented pegged and keeled glenoid components were inserted into all the specimens using standard instrumentation.
Five reproducible lengths (Body width), Posterior wall length, Anterior Wall length. Glenoid body length and corrected body width) and the retroversion angle of the glenoid were identified on the CT scans. These measurements were taken at the 25th, 50th and 75th percentiles of the height of each glenoid both pre and post replacements. Further post glenoid replacement CT scans were analysed for cement-fill of the glenoid cavity and cortical encroachment of the prosthesis.
There was significant correlation of all the measurements including the retroversion angle between the pre and post glenoid replacements at all levels. All but one pegged prosthesis had insufficient cement mantle or critical penetration or abutment at one of the pegs at least. Most often the penetration or cortical abutment was along the posterior wall. All keeled prosthesis had a sufficient cement mantle all around.
The designs of the glenoid prosthesis were satisfactory with some respects like radius of curvature, size and to a certain degree the shape. The margin of error for insertion of the pegged prosthesis was very narrow. Design changes are required in the glenoid component for better bony fixation.
These abstracts were prepared by Mr Cormac Kelly. Correspondence should be addressed to him c/o British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
