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.
Rotator cuff arthropathy is characterised by pain and loss of function. Surgical management of the condition is difficult and controversial. We have conducted a direct comparison between two shoulder replacement systems with different design rationales specifically recommended for the management of rotator cuff arthropathy. 15 patients who had previously undergone bipolar shoulder replacements (BIOMET) were matched for sex and age with patients who underwent DELTA reverse geometry shoulder replacements (DEPUY). All patients in this study were over 70 years old and had rotator cuff arthropathy with pain as their primary complaint and with a maximum active elevation of their arm of 50°. Patients were assessed clinically and radiologically, preoperatively in the 12 months after surgery. All patients benefited from surgery with regard to pain relief, but the improvement as measured on the visual analogue scale was greater in those with the reverse geometry group (p<
0.05). Active range of movements was only marginally improved in the bipolar group. However there was a marked improvement in the reverse geometry group with 14 out of 15 patients able to actively elevate their arm about shoulder height. This was a highly statistically significant finding (p<
0.01). This case comparison study strongly supports the reverse geometry design rationale over the bipolar design for the management of rotator cuff arthropathy in the elderly.
Neer reconstruction remains a gold-standard operation. Standard rehabilitation regime is early mobilization to prevent the development of stiffness of the shoulder. However, an aggressive early rehabilitation may lead to non-healing of the greater tuberosity.
