Glenohumeral arthritis is associated with eccentric posterior glenoid wear and subsequent retroversion. Total shoulder arthroplasty provides a reliable and robust solution for this pattern of arthritis but success may be tempered by malposition of the glenoid component, resulting in pain, functional impairment, prosthetic loosening and ultimately failure. Correction of glenoid retroversion through anterior eccentric reaming, prior to glenoid component implantation, is performed to restore normal joint biomechanics and maximise implant longevity.

The aim of this study was to assess whether magnetic resonance imaging (MRI) or plain axillary radiography (XR) most accurately assessed glenoid version and hence provided the optimal modality for pre-operative templating.

Glenoid version was assessed in pre-operative shoulder MRIs and axillary radiographs (XR) by two independent observers in forty-eight consecutive patients undergoing total shoulder arthroplasty.

The mean glenoid version measured on magnetic resonance imaging was −14.3 degrees and −21.6 degrees on axillary radiographs (mean difference −7.36, p=<0.001). Glenoid retroversion was overestimated in 73% of XRs. Intra-observer and inter-observer reliability coefficients for MRI were 0.96 and 0.9 respectively. Intra-observer and inter-observer reliability coefficients for XR were 0.8 and 0.71 respectively.

Axillary radiographs significantly overestimate glenoid retroversion and are less precise than shoulder magnetic resonance, which provides excellent intra- and inter-observer reliability. MRI is a useful pre-operative osseous imaging modality for total shoulder arthroplasty as it offers a more precise method of determining glenoid version, in addition to the standard assessment rotator cuff integrity.

Total Shoulder Resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics.

This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR. This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated.

Synthes Epoca instruments generated average temperatures of 40.7°^C (SD 0.9°^C) in the rheumatoid group and 56.5°^C (SD 0.87°^C) in the osteoarthritis group (p = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°^C (SD 1.2°^C). Saw bone analysis generated temperatures of 58.2°^C (SD 0.79°^C) in the Synthes (Epoca) 59.9°^C (SD 0.81°^C) in Biomet (Copeland) and 58.4°^C (SD 0.88°^C) in the Depuy (CAP) reamers (p=0.12).

Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°^C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels, and should be performed regularly during this step in TSR.