2015 ISAKOS Biennial Congress ePoster #2115
Total Shoulder Resurfacing Effectively Restores Humeral Anatomy in Cases with Significant Humeral Head Deformity
Justin R. Knight, MD, Hollywood, FL UNITED STATES
John E. Zvijac, MD, Coral Gables, FL UNITED STATES
John W. Uribe, MD, Coral Gables, FL UNITED STATES
UHZ Sports Medicine Institute, Coral Gables, Florida, USA
FDA Status Cleared
Summary: Total shoulder resurfacing using an ovoid humeral component effectively restores predicted normal humeral anatomy in cases with a significant degree of preoperative humeral head flattening deformity.
Total shoulder resurfacing is a technique that has several advantages when compared to a traditional total shoulder arthroplasty for degenerative joint conditions. One of the major claims by implant designers is that this option effectively restores patient native anatomy, however some studies have shown an increase in glenohumeral offset postoperatively. The objectives of this study were to determine if the increase in postoperative offset is related to the degree of preoperative humeral head flattening deformity, and to assess the ability of a resurfacing implant to restore the humeral radius of curvature to a predicted normal value. Our hypothesis was that there will be a greater change in humeral head offset with greater preoperative humeral head deformity, and that there will no difference in the predicted normal humeral head ROC and the postoperative humeral head ROC following the resurfacing procedure.
Preoperative and postoperative radiographs from patients undergoing total shoulder resurfacing were retrospectively reviewed. All procedures were performed using an ovoid humeral resurfacing implant with a central cannulated screw along with a cemented inlay glenoid component. The modified length of glenohumeral offset (LGHO), radius of curvature of the humeral head, and neck-shaft angle of the humerus were measured on a preoperative true AP radiograph of the shoulder. The modified LGHO was measured on a postoperative true AP radiograph of the shoulder. The difference in LGHO between pre and postoperative conditions was calculated. The neck shaft angle was used to predict the normal radius of curvature (ROC) of the humeral head. The difference between the actual ROC of the humeral head and the predicted normal ROC was determined to quantify the degree of humeral head deformity. Significant deformity was defined as a difference between actual and predicted humeral head ROC greater than 2mm, whereas values less than 2mm depicted marginal deformity. The implant ROC was then compared to the predicted normal ROC to assess restoration of the patients’ anatomy. Statistical analysis was performed.
Of the patients who met inclusion criteria, 56 shoulders in 50 patients were radiographically evaluated. There were 32 shoulders with marginal deformity, whereas 24 shoulders had significant deformity. There was an increase of 3.5mm in modified LGHO postoperatively compared with the preoperative condition (p = 0.003). The difference between pre and postoperative LGHO measurements was increased in patients with significant deformity compared with marginal deformity, 6.1mm versus 1.6mm, respectively (p < 0.0001). There was a non-statistically significant average difference of 0.08mm between the ROC of the humeral implant and the predicted normal humeral head for the entire group (p = 0.868). This difference only increased to 1.3 mm in cases with significant humeral head deformity (p = 0.15), which was not a statistically significant difference.
Total shoulder resurfacing using an ovoid humeral implant effectively restores predicted normal humeral anatomy in cases with a significant degree of preoperative humeral head flattening deformity.