Glenoid replacement in total shoulder arthroplasty

Advances in glenoid replacement have contributed to improved patient outcomes and satisfaction while decreasing complications following total shoulder arthroplasty.     

Glenoid component failure in total shoulder arthroplasty

Glenoid component failure is the most common complication of total shoulder arthroplasty. Glenoid components fail as a result of their inability to replicate essential properties of the normal glenoid articular surface to achieve durable fixation to the underlying bone, to withstand repeated eccentric loads and glenohumeral translation, and to resist wear and deformation. The possibility of glenoid component failure should be considered whenever a total shoulder arthroplasty has an unsatisfactory result. High-quality radiographs made in the plane of the scapula and in the axillary projection are usually sufficient to evaluate the status of the glenoid component. Failures of prosthetic glenoid arthroplasty can be understood in terms of failure of the component itself, failure of seating, failure of fixation, failure of the glenoid bone, and failure to effectively manage eccentric loading. An understanding of these modes of failure leads to strategies to minimize complications related to prosthetic glenoid arthroplasty.     

Glenoid revision surgery after total shoulder arthroplasty.

Forty-eight shoulders that underwent glenoid component revision surgery were reviewed at a mean of 4.9 years (range, 2 to 12 years). The indications for surgery were glenoid component loosening in 29 shoulders, glenoid implant failure in 14 shoulders, and glenoid component malposition or wear leading to instability in 5 shoulders. Seventeen shoulders had associated instability. Thirty shoulders underwent implantation of a new glenoid component and 18 underwent removal of the component and bone grafting for bone deficiencies. There was significant pain relief, improvement in active elevation and external rotation, and satisfaction with revision glenoid surgery (P <.05). Patients without a glenoid component were significantly less satisfied with the procedure than those patients who underwent reimplantation of a glenoid component (P =.01). Satisfactory pain relief was achieved in 86% of patients with a new glenoid component and 66% of patients who underwent glenoid component removal. Seven shoulders with a new glenoid component (2 for glenoid loosening) and 5 who underwent removal without reimplantation (3 for painful glenoid arthritis) required re-revision surgery. Eleven of the 17 patients with instability were stable at the most recent follow-up. The data from this study suggest that at the time of revision glenoid surgery, patients who have placement of a glenoid component have a higher degree of satisfaction than those undergoing glenoid component removal. Patients who continue to have pain after bone grafting without placement of a component may be candidates for glenoid component placement after graft consolidation.     

Compaction bone-grafting in prosthetic shoulder arthroplasty

BACKGROUND: Compaction bone-grafting has been suggested as a means of improving the stability of the humeral component in shoulder arthroplasty, but the clinical and radiographic results of the procedure have not been reported in the literature, to our knowledge. To address this deficit, we report on a series of shoulder arthroplasties performed with compaction bone-grafting to secure humeral component fixation. These prostheses were implanted in shoulders demonstrating a suboptimal interference fit of the humeral component. METHODS: Fifty-eight shoulders in fifty-three patients were treated with prosthetic shoulder arthroplasty that included compaction bone-grafting. Clinical assessments were performed at regular intervals with use of visual analog scales for pain, shoulder comfort and function, and overall quality of life, and with use of patient self-assessments including the American Shoulder and Elbow Surgeons Score and the validated Simple Shoulder Test. A detailed radiographic analysis was performed by three raters to determine whether radiolucent lines were present immediately postoperatively and at a later follow-up interval. The humeral tilt angle was determined by measuring the angle between the humeral axis and the component. Subsidence was also evaluated. The mean of the raters' measurements was used in the analysis. RESULTS: The mean duration of follow-up was sixty-nine months (range, twenty-six to 148 months). No loose stems were observed, and no humeral component was revised. At the time of follow-up, there was significant improvement in the Simple Shoulder Test scores and all visual analog scores (p < 0.0001 in each instance). Thirty-four stems had no radiolucent line at the time of follow-up, and the mean maximum thickness of the lucent lines was 0.21 mm in the entire group of fifty-eight shoulders. Most lucent lines occurred near the distal stem tip. The mean tilt of the valgus and varus humeral components was 2.2 degrees and 2.6 degrees , respectively, on the immediate postoperative radiographs. No humeral component shifted from varus to valgus or vice versa. The duration of follow-up was not correlated with the maximum thickness of the humeral component lucency, and the presence or absence of a prosthetic glenoid was also unrelated to the maximum thickness of the lucency. CONCLUSIONS: Compaction bone-grafting in shoulder arthroplasty can yield stable and durable fixation of the humeral component, as seen clinically and radiographically, without use of cement. Our findings provide evidence that compaction bone-grafting in shoulder arthroplasty is an option to ensure intermediate-term fixation (at a mean of five years) of humeral components that have a suboptimal fit.     

Glenoid loosening in total shoulder arthroplasty. Association with rotator cuff deficiency

Seven cases of total shoulder arthroplasty exhibiting major glenoid radiolucent lines or actual translation of the glenoid component were evaluated to identify factors associated with glenoid loosening. The average time from arthroplasty was 30 months (range, 14-44 months). Six of the patients had severe, incompletely reconstructable rotator cuff tears present at the time of surgery, and one patient developed a cuff tear within 1 year of surgery. The amount of superior migration of the humeral component was closely correlated with the degree of glenoid loosening. With superior displacement of the humeral component, superior tipping of the glenoid component was observed: a "rocking horse" glenoid. For comparison, a contemporary group of 16 consecutive total shoulder arthroplasty patients with intact rotator cuffs were reviewed. The control group had no glenoid loosening an average of 5 years after operation. Upward riding of the prosthetic humeral head in patients with rotator cuff deficiency may contribute to loosening of the glenoid component in total shoulder arthroplasty.     

Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid.

BACKGROUND: The marked loss of glenoid bone volume or alteration of glenoid version can affect glenoid component fixation in patients undergoing total shoulder arthroplasty. The purpose of this study was to evaluate the long-term results associated with the use of bone-grafting for restoration of glenoid volume and version at the time of total shoulder arthroplasty. METHODS: Twenty-one shoulders received an internally fixed, corticocancellous bone graft for the restoration of peripheral glenoid bone stock at the time of total shoulder arthroplasty between 1980 and 1989. Grafting was indicated when glenoid bone stock was insufficient to maintain adequate version or fixation of the prosthesis. Seventeen shoulders were available for follow-up; the average duration of follow-up for the thirteen shoulders that did not have prosthetic failure within the first two years was seventy months. Total shoulder arthroplasty was performed because of osteoarthritis in five shoulders, chronic anterior fracture-dislocation in five, capsulorrhaphy arthropathy in three, inflammatory arthritis in two, recurrent dislocation in one, and failure of a previous arthroplasty in one. All patients had some form of anterior or posterior instability preoperatively. There were five anterior and twelve posterior glenoid defects. Bone from the resected humeral head was used for grafting in fifteen shoulders, and bicortical iliac-crest bone was used in two. RESULTS: The average glenoid version after grafting was 4 degrees of retroversion, with an average correction of 33 degrees. The graft failed to maintain the original correction in three shoulders due to nonunion, dissolution, or shift. Five total shoulder replacements failed, necessitating glenoid revision at two to ninety-one months postoperatively. The failures were associated with recurrent massive cuff tears (one shoulder), persistent instability (two shoulders), improper component placement (one shoulder), and loss of graft fixation (one shoulder). There were no humeral component failures. According to the criteria of Neer et al., the functional result was rated as excellent in three shoulders, satisfactory in six, and unsatisfactory in eight. CONCLUSIONS: Despite the finding that eight shoulders had an unsatisfactory functional result at the time of longterm follow-up, corticocancellous grafting of the glenoid successfully restored glenoid version and volume in fourteen of the seventeen shoulders in the present study. Patients with glenoid deficiency often have associated glenohumeral instability, which may affect the results of total shoulder arthroplasty. Bone-grafting of the glenoid is a technically demanding procedure that can restore bone stock in patients with structural defects.     

Glenoid bone loss in primary total shoulder arthroplasty: evaluation and management

Glenohumeral osteoarthritis is the most common reason for shoulder replacement. Total shoulder arthroplasty provides reliable pain relief and restoration of function, with implant survivorship reported at 85% at 15 years. Glenoid component wear and aseptic loosening are among the most common reasons for revision. Glenoid wear characteristics have been correlated with, among other things, the degree of anatomic glenoid version correction. Anatomic glenoid reconstruction is particularly challenging in the presence of glenoid bone deficiency. Walch classified glenoid morphology into five types: type A, centered, without posterior subluxation but with minor erosion (A1) or major erosion (A2); type B, posteriorly subluxated (B1) or posteriorly subluxated with posterior glenoid erosion (B2); and type C, excessive glenoid retroversion. The type A glenoid represents only 59% of patients; thus, the need to address glenoid deformity is common. Methods of correction include asymmetric reaming of the anterior glenoid, bone grafting of the posterior glenoid, and implanting a specialized glenoid component with posterior augmentation. In many cases of type C or hypoplastic glenoid, the humerus is concentrically reduced in the deficient glenoid and glenoid deformity may not need to be corrected. Severely hypoplastic glenoid may require the use of bone-sparing glenoid components or reverse total shoulder arthroplasty.     

Glenoid loosening after total shoulder arthroplasty: An in vitro CT‐scan study

Glenoid fixation failure has only been grossly characterized. This lack of information hinders attempts to improve fixation because of a lack of methodologies for detecting and monitoring fixation failure. Our goal was twofold: to collect detailed data of glenoid fixation fracture, and to investigate computed tomography (CT)‐scanning as a tool for investigations of fixation failure. Six cadaver scapulas and six bone‐substitute specimens were cyclically loaded and CT‐scanned at clinical settings after 0, 1,000, 5,000, 10,000, 30,000, 50,000 and 70,000 load cycles. The fixation status was evaluated by inspection of the scans. After 70,000 cycles, the specimens were sectioned, and the fixation inspected by microscopy. The results of the microscopy analysis were compared to the CT‐scan analysis. Fracture of the glenoid fixation initiated at the edge of the glenoid rim and propagated towards and around the keel of the implant. The entire process from initiation to complete fracture took place at the polyethylene implant–cement interface, while the cement, the adjacent bone, and the cement–bone interface remained intact. Thus, strengthening the polyethylene–cement interface should improve glenoid fixation. Microscopy results validated the CT methodology, suggesting that the CT technique is reliable. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1589–1595, 2009     

Bilateral anatomic total shoulder arthroplasty versus reverse shoulder arthroplasty

The results of anatomic total shoulder arthroplasty and reverse shoulder arthroplasty have previously been reported separately. Although the indications differ, scenarios exist in which a patient may have a total shoulder arthroplasty on 1 shoulder and a reverse shoulder arthroplasty on the contralateral shoulder.Between 1992 and 2009, twelve patients underwent bilateral sequential primary shoulder arthroplasty with a total shoulder arthroplasty on 1 side and reverse shoulder arthroplasty on the contralateral side. Constant score, American Shoulder and Elbow Surgeons (ASES) score, subjective shoulder value, and patient satisfaction were obtained a minimum 1 year postoperatively. Mean postoperative Constant score was 77 after total shoulder arthroplasty and 73 after reverse shoulder arthroplasty (P<.2488). Mean postoperative active forward flexion was similar after total shoulder arthroplasty compared with reverse shoulder arthroplasty (P=.8910). Greater external rotation at the side (43° vs 12°; P<.0001) and internal rotation (T8 vs L1; P<.0001) were observed after total shoulder arthroplasty. Mean ASES score was 89.6 after total shoulder arthroplasty compared with 82.4 after reverse shoulder arthroplasty (P=.0125). Patient satisfaction was 92% for both prostheses, and mean subjective shoulder value was similar (85.4% vs 82.5%; P=.6333).Bilateral shoulder arthroplasty performed with a total shoulder arthroplasty and reverse shoulder arthroplasty on opposite shoulders can provide good functional outcome and high patient satisfaction. Although range of motion is better following total shoulder arthroplasty, no difference was observed in final Constant score or subjective patient assessment.