Jonathan C. Levy

Reverse Shoulder Arthroplasty for the Treatment of Rotator Cuff Deficiency

BACKGROUNDnEarly designs of reverse shoulder arthroplasty components for the treatment of glenohumeral arthritis associated with severe rotator cuff deficiency in some cases have been associated with mechanical failure. The purpose of this study was to perform a prospective outcomes study of reverse shoulder arthroplasty performed with use of 5.0-mm peripheral locking screws for baseplate fixation and a lateralized center of rotation for the treatment of a rotator cuff deficiency.nnnMETHODSnFrom February 2004 to March 2005, 112 patients (114 shoulders) were treated with a reverse shoulder arthroplasty as part of a United States Food and Drug Administration Investigational Device Exemption study. Ninety-four patients (ninety-six shoulders) were available for a minimum follow-up of two years. Of the ninety-six shoulders, thirty-seven had a primary rotator cuff deficiency, thirty-three had a previous rotator cuff operation, twenty-three had a previous arthroplasty, and three had a proximal humeral nonunion. The patients were prospectively followed clinically (the American Shoulder and Elbow Surgeons [ASES] score, the Simple Shoulder Test [SST], and self-reported satisfaction) and radiographically (mechanical failure, loosening, and notching). Patients were videotaped while performing a standard active range-of-motion protocol before and after treatment. These videos were then analyzed in a blinded fashion by three independent observers using a digital goniometer.nnnRESULTSnAt two years, the average total ASES scores had improved from 30 preoperatively to 77.6; the average ASES pain scores, from 15 to 41.6; and the average SST scores, from 1.8 to 6.8 (p < 0.0001 for all). Blinded analysis of range of motion showed that average abduction improved from 61 degrees preoperatively to 109.5 degrees (p < 0.0001); average flexion, from 63.5 degrees to 118 degrees (p < 0.0001); and average external rotation, from 13.4 degrees to 28.2 degrees (p < 0.0001). The patients rated the outcome as excellent in fifty-three shoulders (55%), good in twenty-six (27%), satisfactory in eleven (12%), and unsatisfactory in six (6%). There was no evidence of mechanical failure of the baseplate or scapular notching in any of the patients. Six of the ninety-four patients in this study had a complication.nnnCONCLUSIONSnRecent advances in reverse shoulder arthroplasty have allowed for improvement in patient outcomes while minimizing early mechanical failure and scapular notching and decreasing the overall complication rate at short-term follow-up.

The Use of the Reverse Shoulder Prosthesis for the Treatment of Failed Hemiarthroplasty for Proximal Humeral Fracture

BACKGROUNDnHumeral hemiarthroplasty is an established treatment for patients with selected fractures of the proximal part of the humerus. However, a subset of patients have development of glenoid arthritis and rotator cuff deficiency due to tuberosity failure. To date, there has been no reliable salvage procedure for this problem.nnnMETHODSnOver a period of five years, twenty-nine patients (twenty-five women and four men) with a mean age of sixty-nine years (range, forty-two to eighty years) were managed with removal of a hemiarthroplasty prosthesis and revision with a Reverse Shoulder Prosthesis alone or in combination with a proximal humeral allograft. Patients were followed clinically and radiographically for an average of thirty-five months. All patients were evaluated with use of the American Shoulder and Elbow Surgeons score; the Simple Shoulder Test; range-of-motion measurements, including abduction, forward flexion, and external rotation; and a rating scale for overall satisfaction with the outcome of the surgery. Patients were assessed preoperatively and at all follow-up points beginning at three months postoperatively.nnnRESULTSnThe average total American Shoulder and Elbow Surgeons score improved from 22.3 preoperatively to 52.1 at the time of the last follow-up (p < 0.001). The average American Shoulder and Elbow Surgeons pain score improved from 12.2 to 34.4 (p < 0.001), and the average American Shoulder and Elbow Surgeons function score improved from 10.1 to 17.7 (p = 0.058). The average Simple Shoulder Test score improved from 0.9 to 2.6 (p = 0.004). Forward flexion improved from 38.1 degrees to 72.7 degrees (p < 0.001), and abduction improved from 34.1 degrees to 70.4 degrees (p < 0.001). The overall complication rate was 28% (eight of twenty-nine). At the time of the latest follow-up, sixteen patients rated the outcome as good or excellent, seven rated it as satisfactory, and six were dissatisfied. Four of the six patients who were dissatisfied had been managed with a Reverse Shoulder Prosthesis alone.nnnCONCLUSIONSnThe Reverse Shoulder Prosthesis offers a salvage-type solution to the problem of failed hemiarthroplasty due to glenoid arthritis and rotator cuff deficiency following tuberosity failure. The early results reported here are promising. In cases of severe proximal humeral bone deficiency, augmentation of the Reverse Shoulder Prosthesis with a proximal humeral allograft may improve patient satisfaction.

The treatment of deep shoulder infection and glenohumeral instability with debridement, reverse shoulder arthroplasty and postoperative antibiotics

We retrospectively reviewed 21 patients (22 shoulders) who presented with deep infection after surgery to the shoulder, 17 having previously undergone hemiarthroplasty and five open repair of the rotator cuff. Nine shoulders had undergone previous surgical attempts to eradicate their infection. The diagnosis of infection was based on a combination of clinical suspicion (16 shoulders), positive frozen sections (> 5 polymorphonuclear leukocytes per high-power field) at the time of revision (15 shoulders), positive intra-operative cultures (18 shoulders) or the pre-operative radiological appearances. The patients were treated by an extensive debridement, intravenous antibiotics, and conversion to a reverse shoulder prosthesis in either a single- (10 shoulders) or a two-stage (12 shoulders) procedure. At a mean follow-up of 43 months (25 to 66) there was no evidence of recurrent infection. All outcome measures showed statistically significant improvements. Mean abduction improved from 36.1 degrees (sd 27.8) pre-operatively to 75.7 degrees (sd 36.0) (p < 0.0001), the mean forward flexion from 43.1 degrees (sd 33.5) to 79.5 degrees (sd 43.2) (p = 0.0003), and mean external rotation from 10.2 degrees (sd 18.7) to 25.4 degrees (sd 23.5) (p = 0.0037). There was no statistically significant difference in any outcome between the single-stage and the two-stage group.

Glenoid morphology in reverse shoulder arthroplasty: Classification and surgical implications

BACKGROUNDnA great challenge in reverse shoulder arthroplasty is the wide variation in glenoid morphology that adds uncertainties in glenoid component placement. The purpose of this study was to classify glenoid morphology and examining its effect on possible glenoid component fixation.nnnMATERIALS AND METHODSnThe morphology of 216 glenoids was classified into normal and abnormal with subgroups defined by erosion sites. Six anatomic and 2 surgical parameters were compared among the classified groups. Plain radiographs or 2-dimensional (2D) computed tomography (CT) scans showed 62.5% of glenoids were normal and 37.5% were abnormal, with further subclassification of abnormal in posterior (17.6%), superior (9.3%), global (6.5%), and anterior (4.2%) erosions using 3D CT models.nnnRESULTSnThe standard centerline became significantly shorter in abnormal (19.6 +/- 9.1 mm) than in normal (28.6 +/- 4.1 mm, P < .0001) glenoids. Alternatively, the spine centerline provided longer bony distance in abnormal glenoids (34.9 +/- 17.0 mm). Abnormal glenoid morphology also reduced peripheral screw placement area by 42% and limited it to the anterior and inferior quadrants.nnnDISCUSSIONnGlenoid morphology of the rotator cuff deficient shoulder can be reliably classified using this classification system consisting of normal and abnormal, which included 4 subgroups of posterior, superior, global, and anterior erosions.nnnCONCLUSIONSnAbnormal glenoid morphology was shown to have a significant effect on anatomical and surgical factors which can necessitate adjustments in surgical technique for reverse shoulder arthroplasty.nnnLEVEL OF EVIDENCEnBasic Science Study.

Revision Arthroplasty with Use of a Reverse Shoulder Prosthesis-allograft Composite

BACKGROUNDnPatients with disabling pain and loss of shoulder function with associated proximal humeral bone loss following shoulder arthroplasty have limited reliable treatment options. Our objective was to report the results, obtained as part of a prospective outcomes study, of the use of a reverse shoulder prosthesis-allograft composite in these patients.nnnMETHODSnBetween 2002 and 2005, 353 patients treated with a reverse shoulder prosthesis were enrolled in a prospective cohort study. Twenty-five patients received, in addition, a proximal humeral allograft for the management of severe proximal humeral bone loss, and they comprise the study group. The average bone loss measured 53.6 mm (range, 34.5 to 150.3 mm). Patients were followed clinically with use of the American Shoulder and Elbow Surgeons (ASES) score, the Simple Shoulder Test (SST), and a scale with which the patients rated their satisfaction, and they were followed radiographically to detect mechanical failure, loosening, notching, and graft healing. All patients were followed for a minimum of two years (average, 30.2 months).nnnRESULTSnThe total average ASES score improved from 31.7 points preoperatively to 69.4 points at the time of follow-up (p < 0.0001), and the average SST score improved from 1.4 to 4.5 points (p < 0.0001). Nineteen patients (76%) reported a subjective good or excellent result, five reported a satisfactory result, and one reported that the result was unsatisfactory. The range of motion improved in forward flexion (from 32.7 degrees to 82.4 degrees ; p < 0.0001), abduction (from 40.4 degrees to 81.4 degrees ; p < 0.0001), and internal rotation. Radiographic evaluation at the time of final follow-up showed incorporation of the allograft in the metaphyseal region in 84% (twenty-one) of the twenty-five patients and incorporation of the allograft in the diaphyseal region in 76% (nineteen) of the patients. Four patients had complications.nnnCONCLUSIONSnUse of a reverse shoulder prosthesis-proximal humeral allograft composite for the treatment of shoulder dysfunction following arthroplasty associated with substantial proximal humeral bone loss has shown promising early results. The allograft may restore proximal humeral bone stock, thereby helping to maintain the height of the prosthesis bone construct and thus deltoid tension. Additional, long-term studies are needed to evaluate the longevity of this construct.

Hierarchy of Stability Factors in Reverse Shoulder Arthroplasty

Reverse shoulder arthroplasty is being used more frequently to treat irreparable rotator cuff tears in the presence of glenohumeral arthritis and instability. To date, however, design features and functions of reverse shoulder arthroplasty, which may be associated with subluxation and dislocation of these implants, have been poorly understood. We asked: (1) what is the hierarchy of importance of joint compressive force, prosthetic socket depth, and glenosphere size in relation to stability, and (2) is this hierarchy defined by underlying and theoretically predictable joint contact characteristics? We examined the intrinsic stability in terms of the force required to dislocate the humerosocket from the glenosphere of eight commercially available reverse shoulder arthroplasty devices. The hierarchy of factors was led by compressive force followed by socket depth; glenosphere size played a much lesser role in stability of the reverse shoulder arthroplasty device. Similar results were predicted by a mathematical model, suggesting the stability was determined primarily by compressive forces generated by muscles.

Young patients with shoulder chondrolysis following arthroscopic shoulder surgery treated with total shoulder arthroplasty.

Chondrolysis following shoulder arthroscopy is a devastating complication, often seen in young patients. After nonoperative measures have been exhausted, there are few treatment options available that reliably improve pain and function. The purpose of this study is to examine the intra-operative findings, radiographic features, and clinical outcomes of a series of patients with chondrolysis following arthroscopic surgery managed with a total shoulder arthroplasty. A retrospective review was performed on 11 patients (average age 39) with shoulder chondrolysis following arthroscopy. Attention was focused on review of the index arthroscopy, radiographs, and functional outcome scores prior to total shoulder arthroplasty, as well as intra-operative cultures, histology, radiographs, and functional outcomes from most recent follow-up. All patients were treated with total shoulder arthroplasty at an average of 26 months after the index arthroscopy. Preoperative and postoperative radiographs were reviewed, and outcomes were compared using validated measurements. Statistically significant improvements in shoulder abduction (89 degrees -123 degrees , P = .027), external rotation (26 degrees -48 degrees , P = .037), total ASES scores (30-77.5, P = .0039), and SST scores (3-8, P = .0078) were noted. Ten patients subjectively rated their outcomes as good or excellent, with 1 as satisfactory. Chondrolysis after shoulder arthroscopy has a rapid clinical progression and is likely multifactorial in etiology. Early results of total shoulder arthroplasty show an opportunity for improvements in pain and function; however, progressive glenoid radiolucencies may develop in these patients.

Center of rotation affects abduction range of motion of reverse shoulder arthroplasty.

Although clinical outcomes of the reverse shoulder replacement have noted improvements in pain and function, evaluation of these outcomes reveals concerns regarding progressive scapular notching and variability of functional improvements in range of motion. Therefore, an apparatus was designed to examine differences in abduction range of motion for seven configurations of reverse shoulder arthroplasty. An electronic goniometer was used to measure abduction range of motion, and digital video analysis was used to determine impingement points. Finally, a correlation analysis between range of motion and the effect of changing the center of rotation of the glenosphere was performed. As the center of rotation was moved more lateral from the glenoid, abduction range of motion increased. The greatest range of motion was 97° ± 0.9° using a glenoid component with a center of rotation offset 10 mm ± 0.4 mm from the glenoid. The smallest range of motion was 67° ± 1.8° using a glenosphere with a center of rotation offset 0.5 mm ± 0.1 mm from the glenoid surface. Range of motion always was limited by impingement points on the scapula. Inferiorly, adduction was limited by impingement on either the inferior scapular border or the glenoid. Superiorly, abduction was limited by impingement on the acromion. A positive linear correlation was found between abduction range of motion and center of rotation offset relative to the glenoid.

In vitro and finite element analysis of glenoid bone/baseplate interaction in the reverse shoulder design

We developed biomechanical and finite element models, using high-strength polyurethane foam blocks, to represent the glenoid bone/baseplate junction to determine if increasing the distance between the glenoid bone and the center of rotation of the glenosphere increases baseplate motion during static loading in the reverse shoulder design. Although there was a general trend toward increased baseplate motion with increasing distance from the glenoid to the center of rotation, in vitro mechanical testing revealed no significant difference between the 7 glenosphere types tested, with average baseplate motion during 1000 load cycles ranging from 90 mum to 120 mum. Results from the finite element analysis strongly correlated with the in vitro mechanical testing. The magnitude of baseplate motion occurring in a modeled representation of bone under simulated physiologic loading conditions was similar for the 7 reverse shoulder glenoid components tested in this study.

Scapular fractures after reverse shoulder arthroplasty: evaluation of risk factors and the reliability of a proposed classification

BACKGROUNDnThe aims were to determine the sensitivity of plain radiographs to detect scapular fractures after reverse shoulder arthroplasty (RSA), to test the reliability of a proposed classification, and to evaluate risk factors.nnnMATERIALS AND METHODSnWe matched 53 patients with scapular fractures after RSA to 212 control patients. Clinical risk factors were assessed by correlating comorbidities. Independent observers reviewed radiographs to assess fracture detection accuracy and test the reliability of a proposed classification. Radiographic risks were evaluated by measuring acromial thickness, acromial tilt, glenoid-to-tuberosity distance, and acromion-to-tuberosity (AT) distance.nnnRESULTSnIndependent reviewers accurately diagnosed 78.8% of fractures and 97.4% of controls with good inter-rater reliability (κ = 0.782) and excellent intrarater reliability (κ = 0.862). Inter-rater reliability of the classification was moderate (κ = 0.422). Osteoporosis significantly increased the risk of fracture (odds ratio, 1.97; 95% confidence interval, 1.00-3.91); however, no difference was found for other comorbidities or between preoperative and postoperative radiographic parameters. A significant difference occurred between groups from the postoperative radiographs to the most recent radiographs for AT distance (0.4 ± 5.5 mm for control group and 8.3 ± 7.6 mm for fracture group, P < .001) and acromial tilt (1.8° ± 6.3° for control group and 14° ± 15° for fracture group, P < .001). Of 16 scapular spine fractures, 14 occurred from a screw tip; however, screw orientation and length were not different between groups.nnnCONCLUSIONnOsteoporosis is a significant risk factor for scapular fractures after RSA. The current classification has only moderate reliability, suggesting that an alternative classification method is needed. Decreasing AT distance and increasing acromial tilt on consecutive radiographs may improve fracture detection. Advanced imaging may be needed to confirm the diagnosis. Whereas most scapular spine fractures occurred from a screw, the surgical technique did not increase the relative risk.