Total shoulder arthroplasty (TSA) is being performed with increasing frequency. According to recent data, the number of TSAs performed annually increased 2.5-fold from 2000 to 2008.1 As more are performed, the need for improved implant survival will increase as well. In particular, advances in glenoid survivorship will be a primary focus. Previous experience has demonstrated that the glenoid component is the most common source of loosening and failure, and glenoid loosening has been documented in 33% to 44% of arthroplasties, with the rate of radiographically lucent lines even higher.2-5 Thus, a correlation between increasing incidence of procedures and high rates of glenoid loosening represents the potential for a significant increase in the number of future revisions. A recent report from Germany indicated that TSA had a 3-fold higher relative burden of revision than hemiarthroplasty.6
Ingrowth metal-backed glenoid components offer the theoretical advantage of bone growth directly into the prosthesis with a single host–prosthesis interface. Use of a novel tantalum glenoid may avoid the stress-shielding, component-stiffness, dissociation, and backside-wear issues that have produced the high failure rates of conventional metal-backed glenoids. According to the literature, the multiple different-style cementless glenoids being used have had unpredictable outcomes and demonstrated an increased need for revisions.7-11
In this article, we present a case series of midterm radiographic and clinical outcomes for TSAs using porous tantalum glenoid components. Our goals were to further understanding of survivorship and complications associated with ingrowth glenoid components and to demonstrate the differences that may occur with use of tantalum.
Materials and Methods
Data were examined for all TSAs performed at a single institution between 2004 and 2013. Before reviewing the data, we obtained approval from the hospital institutional review board. Our retrospective chart review identified all patients who underwent TSA using a tantalum ingrowth glenoid component. Exclusion criteria included revision arthroplasty, use of a non-tantalum glenoid, reverse shoulder arthroplasty, and conversion from hemiarthroplasty to TSA. Twelve shoulders (11 patients) were identified. We obtained patient consent to examine the data collected, and patients were reexamined if they had not been seen within the past 12 months. Figures 1 and 2 show the preoperative radiographs.
The TSAs were performed by 2 fellowship-trained shoulder surgeons using glenoid components with porous tantalum anchors (Zimmer). Indications for this procedure were age under 60 years, no prior surgery, and glenoid morphology allowing for version correction without bone grafting. Patients with severe posterior erosion that required bone graft or with a dysplastic glenoid were not indicated for this glenoid implant.
In each case, the anesthesia team placed an indwelling interscalene catheter, and then the surgery was performed with the patient under deep sedation. The beach-chair position and a deltopectoral approach were used, and biceps tendon tenodesis was performed. The subscapularis was elevated with a lesser tuberosity osteotomy and was repaired with nonabsorbable braided suture at the end of the case. During glenoid implantation, the periphery of the polyethylene was cemented. This is consistent with the approved method of implantation for this device. Closed suction drainage was used. After surgery, the patient was restricted to no weight-bearing. During the first 6 weeks, passive forward elevation was allowed to 130° and external rotation to 30°. Active and active-assisted range of motion was started at 6 weeks, and muscular strengthening was allowed 12 weeks after surgery.
We analyzed standard radiographs at yearly intervals for trabecular bony architecture and lucency surrounding the tantalum anchor of the glenoid. Before and after surgery, American Shoulder and Elbow Surgeons (ASES) scores and active forward elevation (AFE) and active external rotation (AER) measurements were recorded. These measurements served as endpoints of analysis.
Results
Twelve shoulders (11 patients) were identified and examined. Mean follow-up was 20 months (range, 6-84 months). In all cases, annual standard radiographs showed bony trabeculae adjacent to the tantalum anchor without lucency. There was no sign of glenoid loosening in any patient.
ASES scores and AFE and AER measurements were obtained with physical examinations and compared with t tests. ASES scores, available for 8 patients, increased from 32 before surgery to 85 after surgery (P < .01). Mean AFE increased from 117° to 159° (P < .01), and mean AER increased from 23° to 53° (P < .01). Figures 3 and 4 show the postoperative radiographs, and the Table highlights the ASES and range-of-motion data.
Discussion
Data for the 12 TSAs followed in this series showed promising outcomes for cementless ingrowth glenoid components. Much as with other data in the literature, there were significant improvements in ASES scores, AFE, and AER. What differs from the majority of available data is the survivorship and lack of radiolucent lines on follow-up radiographs.