Glenoid bone-grafting in total shoulder arthroplasty

Abnormal glenoid architecture resulting from loss of bone usually is listed among the contraindications to total shoulder arthroplasty using an unconstrained prosthesis. However, in a series of 463 consecutive replacement procedures that were performed between 1973 and 1985, in only two patients did the lack of bone make the implantation of a glenoid component impossible. Of the remaining sixty-five shoulders that had an abnormal glenoid, twenty were successfully treated with a large, internally fixed bone graft or grafts and forty-five, with smaller bone grafts that were not internally fixed. Nineteen of the twenty shoulders that had a large graft or grafts were followed for two years or more (average, 4.4 years). The clinical results were judged to be excellent in sixteen and satisfactory in one, and the desired limited goals were obtained in two. Two fixation screws broke and one screw was worn by contact with the humeral component. None of the glenoid components clinically loosened or migrated, and no patient has needed further surgical treatment. Although bone-grafting was necessary in only twenty (4.3 per cent) of the 463 replacement procedures, this procedure provided sufficient osseous support to allow implantation of a component in a severely damaged glenoid.     

Clinical and radiographic results of eccentric glenoid reaming in reverse total shoulder arthroplasty

BackgroundOne option for treating glenoid bone loss in reverse shoulder arthroplasty (RSA) is eccentric reaming of the glenoid, but the effect on clinical results is unclear. The aim of this study was to investigate the association between medialization of the bone-baseplate interface (herein, ‘medialization’) caused by eccentric reaming of the glenoid and scapular notching, baseplate loosening, and clinical outcomes after RSA.MethodsWe retrospectively reviewed data for 91 patients who underwent primary RSA between January 2014 and December 2016 with a lateralized implant and a minimum 2-year follow-up. The amount of medialization was estimated using a 3-dimensional computed tomography scan-based computer planning software. The average amount of medialization estimated by the 3-dimensional planning software was 3.4 mm (range, 0.5-10 mm). Outcomes included range of motion (ROM), American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST) score, visual analog scale (VAS) for pain, and the rates of scapular notching and baseplate loosening. The association between the estimated medialization and the outcomes of interest was evaluated using multivariate models.ResultsAfter controlling for age, sex, diagnosis, subscapularis repair, glenosphere size, and baseline ROM, medialization was not associated with the postoperative abduction (P = .35), external rotation (ER) at 90° (P = .16), internal rotation at 90° (P = .08), and internal rotation at the back (P = .06). However, we found a significant association between medialization and postoperative ER at the side (P = .02). According to the multivariate model, for a 1-mm increase in medialization during surgery, a decrease of 1.6° in postoperative ER would be expected. We found no association between medialization and the postoperative ASES score (P = .48), SST score (P = .59), or VAS score (P = .27). At a minimum of 2 years of follow-up, we found no baseplate loosening or radiographic signs of baseplate loosening in any patient. Scapular notching of grades 1 to 2 was observed in 22 patients (24%). We were not able to detect a difference in scapular notching when medialization was > 1 mm ver when medialization ≤ 1 mm (odds ratio, 2.5; 95% confidence interval: 0.28-23).ConclusionsIncreasing medialization due to eccentric reaming after RSA with a lateralized implant was associated with a decrease in postoperative ER at the side. However, increasing medialization was not associated with worse patient-reported outcome scores or increased baseplate loosening at short-term follow-up.     

Bipolar implant shoulder arthroplasty. Long-term results

The bipolar shoulder implant (BSI), designed by the senior author in 1975, has an unfixed metal glenoid cup with a polyethylene liner that articulates with a cemented titanium humeral component. The BSI was inserted in 35 shoulders of 33 patients with severe rheumatoid arthritis (20 cases), degenerative arthritis (ten cases), and posttraumatic lesions (five cases). The follow-up period ranged from 24 to 140 months (average, 63 months). Pain relief was good to excellent in 31 shoulders; four experienced some pain during daily activities. After BSI, motion was greatly improved with 71 degrees average range of abduction, 23 degrees range of adduction, 79 degrees range of flexion, 45 degrees range of extension, 76 degrees range of internal rotation, and 28 degrees range of external rotation. BSI was well-tolerated by the bone and soft tissues, with no erosive changes at the coracoacromial arch. There was no evidence of loosening at the cement-bone interface. One patient with a postoperative subcoracoid dislocation maintained a good functional result for more than 11 years. One BSI had draining sinus tract with negative culture, which spontaneously healed following removal of the implants. There were 3.3 mm (range, -7 mm to 11 mm) of superior subluxation of the humeral head on the preoperative roentgenogram. This increased to 8.7 mm (range, -5 mm to 20 mm) in the long-term follow-up roentgenogram. The bipolar implant is specially indicated in the severely arthritic shoulders in patients with vertical humeral subluxation and complicated histories of multiple failed operations.     

Stress analyses of glenoid components in total shoulder arthroplasty

Finite element analysis was used to characterize the local stresses at the bone-implant interface of 2 different types of glenoid components presently used in unconstrained total shoulder arthroplasty. A series of 2-dimensional finite-element meshes was developed to model the glenoid in 2 mutually perpendicular planes with and without implanted components. One of the implants modeled was a cemented all-polyethylene component, and the second was an uncemented metal-backed component. A variety of parameters were studied including the resultant loading direction (concentric versus eccentric), keel geometry, subchondral bone integrity, and cement mantle size. Results of the analyses show that the cemented all-polyethylene design demonstrated an overall stress pattern that was closer to that of the intact glenoid. When the effects of concentric and eccentric loading conditions were compared, the overall stress magnitudes in the subchondral bone were found to be much lower with the uncemented metal-backed component than with its cemented all-polyethylene counterpart. This finding suggests that some degree of stress shielding may be associated with the metal-backed component. In addition, under both the concentric and eccentric loading conditions, extremely high stress regions were found within the polyethylene near the polyethylene-metal interface of the uncemented metal-backed component.     

Uncemented glenoid component in total shoulder arthroplasty. Survivorship and outcomes

BACKGROUND: Glenoid component loosening continues to be a major factor affecting the long-term survivorship of total shoulder replacements. Radiolucent lines, cement fracture, migration, and loosening requiring revision are common problems with cemented glenoid components. The purpose of this study was to evaluate the results of total shoulder arthroplasty with an uncemented glenoid component and to identify predictors of glenoid component failure. METHODS: One hundred and forty-seven consecutive total shoulder arthroplasties were performed in 132 patients (mean age, 63.3 years) with use of an uncemented glenoid component fixed with screws between 1988 and 1996. One hundred and forty shoulders in 124 patients were available for follow-up at an average of 7.5 years. One shoulder in which the arthroplasty had failed at 2.4 years and for which the duration of follow-up was four years was also included for completeness. The preoperative diagnoses included osteoarthritis in seventy-two shoulders and rheumatoid arthritis in fifty-five. RESULTS: Radiolucency was noted around the glenoid component and/or screws in fifty-three of the 140 shoulders. The mean modified ASES (American Shoulder and Elbow Surgeons) score (and standard deviation) improved from 15.6 +/- 11.8 points preoperatively to 75.8 +/- 17.5 points at the time of follow-up. Eighty-five shoulders were not painful, forty-two were slightly or mildly painful, ten were moderately painful, and three were severely painful. Fifteen (11%) of the glenoid components failed clinically, and ten of them also had radiographic signs of failure. Eleven other shoulders had radiographic signs of failure but no symptoms at the time of writing. Three factors had a significant independent association with clinical failure: male gender (p = 0.02), pain (p < 0.01), and radiolucency adjacent to the flat tray (p < 0.001). In addition, the annual risk of implant revision was nearly seven times higher for patients with radiographic signs of failure. Clinical survivorship was 95% at five years and 85% at ten years. CONCLUSIONS: The failure rates of the total shoulder arthroplasties in this study were higher than those in previously reported studies of cemented polyethylene components with similar durations of follow-up. Screw breakage and excessive polyethylene wear were common problems that may lead to additional failures of these uncemented glenoid components in the future.     

Treatment of symptomatic glenoid loosening following unconstrained shoulder arthroplasty

Nine patients with symptomatic glenoid loosening were identified and ultimately underwent surgical revision. Preoperative assessment demonstrated that pain, decreased range of motion, and functional disability were common features. A painful clunking sensation with forward elevation of the arm was noted in four of the nine patients. At surgical revision, a grossly loose glenoid component was found in all cases and removed. Seven of the nine patients underwent revision using another cemented glenoid component, and two patients were left with a hemiarthroplasty due to glenoid bone deficiency. Results following revision surgery demonstrated increased range of motion, decreased pain, and increased functional ability with good overall patient satisfaction in seven of nine patients. Two patients in whom revision glenoid components were implanted were considered failures due to recurrent loosening. Although revision of the glenoid component is often technically feasible, recurrent loosening may occur. Revision to a hemiarthroplasty may be an acceptable alternative to glenoid replacement.     

Constrained total shoulder arthroplasty. Long-term follow-up observations

Constrained total shoulder arthroplasty is a salvage procedure for patients with disabling pain and a nonfunctioning rotator cuff mechanism. Considering the advanced pathologic process and severe symptoms of these patients, the results of pain relief are gratifying. Many of the patients have weak or absent deltoid muscles, and active overhead motion is not possible. A method of attaching the metal glenoid to the scapula has been designed to reduce the risk of loosening. However, constrained total shoulder arthroplasty does produce considerable stress on bony attachments. Careful patient selection and an excellent, carefully supervised postoperative rehabilitation program are mandatory for success. Before considering a constrained total joint arthroplasty, the surgeon should carefully assess the patient's needs and consider other less extensive shoulder reconstructions.     

Rehabilitation following total shoulder arthroplasty

Total shoulder arthroplasty (TSA) is a standard operative treatment for a variety of disorders of the glenohumeral joint. Patients, who have continued shoulder pain and loss of function in the presence of advanced joint pathology, despite conservative management, are often managed by undergoing a TSA. The overall outcomes that are reported after surgical intervention are quite good and appear to be primarily determined by the underlying pathology and the tissue quality of the rotator cuff. The current Neer protocol for postoperative TSA rehabilitation is widely used and based on tradition and the basic science of soft tissue and bone healing. The purpose of this paper is to review the indications for TSA, focusing on the underlying pathologies, and to describe the variables that impact the rehabilitation program of individuals who have had a TSA. A postoperative TSA rehabilitation protocol and algorithm, founded on basic science principles and tailored toward the specific clinical condition, are presented.     

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.     

Clinical results of revision shoulder arthroplasty for glenoid component loosening

We retrospectively reviewed 32 patients who underwent glenoid revision surgery after total shoulder arthroplasty to compare the results of revision total shoulder arthroplasty with those of revision hemiarthroplasty and to identify factors associated with poor results after revision shoulder arthroplasty for glenoid component loosening. Results were reviewed at a mean follow-up of 4 years (range, 2-8 years). Glenoid reimplantation resulted in significant pain relief (P < .0001), improvement in American Shoulder and Elbow Surgeons (ASES) score (P < .02), and external rotation (24 degrees to 44 degrees , P < .004). Revision to a hemiarthroplasty also resulted in significant pain relief (P < .01) and improvement in ASES score (P < .05). For the treatment of glenoid loosening without glenohumeral instability, both reimplantation of a glenoid component and revision to a hemiarthroplasty improved function, satisfaction, and level of pain. Reimplantation of a new glenoid component offered greater improvements in pain (P < .008) and external rotation (increase of 20 degrees versus 3 degrees , P < .03) compared with hemiarthroplasty. For patients with preoperative glenohumeral instability, revision surgery did not improve motion, function, or pain significantly. Risk factors associated with a poor outcome after revision arthroplasty included persistent glenohumeral instability, rotator cuff tears, and malunion of the greater tuberosity.