Evan S. Lederman

Metallosis after hemiarthroplasty as a result of glenoid erosion causing contact with retained metallic suture anchors: a case series

Metallosis is a well-documented cause of joint replacement failure. Metal-on-metal contact leads to increased numbers of metal ions, which form immune protein complexes. This hypersensitivity reaction can lead to aseptic loosening. Although most metallosis failures are described in metal-on-metal hip arthroplasties, it has also been reported in the knee, elbow, and wrist. Arthroscopic or open labral repair is a commonly performed procedure to treat shoulder instability. Glenohumeral arthrosis may develop in these patients as a result of degeneration, chondrolysis, or mechanical causes. Shoulder arthroplasty is often used for pain relief and functional improvement in these patients. We report 3 patients with metallosis that resulted after hemiarthroplasty when existing metallic glenoid suture anchors came into contact with the humeral prosthesis after medial erosion of the glenoid. The only documented case of metallosis in the shoulder is after a total shoulder arthroplasty without any retained hardware or prior procedures.

A prospective, multicenter study to evaluate clinical and radiographic outcomes in primary rotator cuff repair reinforced with a xenograft dermal matrix

BACKGROUND Minimal information is currently available on the outcome of rotator cuff repair reinforced with an extracellular matrix (ECM) graft. Therefore, the purpose of this study was to determine the clinical and radiographic outcome of repair of large rotator cuff tears with ECM graft reinforcement. METHODS This was a prospective study of 61 shoulders with large repairable rotator cuff tears (3 to 5 cm). The rotator cuff tears were surgically repaired and reinforced with a xenograft ECM graft. The average patient age was 56 years (range, 40-69 years). The average tear size was 3.8 cm. RESULTS Follow-up was obtained at 6, 12, and 24 months in 58, 54, and 50 of the 61 patients, respectively. Functional outcome scores, isometric muscle strength, and active range of motion were significantly improved compared with baseline. Magnetic resonance imaging at 12 months showed retorn rotator cuff repairs in 33.9% of shoulders, using the criteria of a tear of at least 1 cm, and tears in 14.5% of the shoulders using the criteria of retear >80% of the original tear size. Three patients underwent surgical revision. Complications included 1 deep infection. CONCLUSIONS Repair of large rotator cuff tears structurally reinforced with xenograft ECM resulted in improved functional outcomes scores and strength. Adverse events were uncommon, and the rate of revision surgery was low.

Healing and functional outcome of a subscapularis peel repair with a stem-based repair after total shoulder arthroplasty

BACKGROUND The purpose of this study was to evaluate functional outcome and healing of a subscapularis peel with a stem-based repair after total shoulder arthroplasty (TSA). The hypothesis was that the repair would lead to subscapularis healing in the majority of cases. METHODS A prospective analysis was performed on a consecutive series of TSAs. Range of motion and functional outcome were assessed according to American Shoulder and Elbow Surgeons, Single Assessment Numeric Evaluation, Simple Shoulder Test, and visual analog scale scores at a minimum follow-up of 1 year. Belly-press and lift-off tests were also performed. An ultrasound evaluation assessed subscapularis healing at final follow-up. RESULTS At a mean follow-up of 15 months, 60 patients (mean age, 64 years) were examined. Mean forward flexion improved from 115° to 137°. External rotation at the side improved from 27° to 52°, and internal rotation improved from L4 to L2 (P < .05). American Shoulder and Elbow Surgeons score improved from 34.3 to 79.8 (P < .001). Likewise, the Single Assessment Numeric Evaluation and Simple Shoulder Test scores showed significant improvement from 33.1 to 85.3 and 4.3 to 10.2, respectively (P < .001). The visual analog scale score for pain decreased from 5.8 to 0.7 (P < .001). On ultrasound examination, the subscapularis was healed intact in 55 cases (91.7%), attenuated in 3 cases (5%), and torn in 2 cases (3.3%). CONCLUSION A stem-based repair of a subscapularis peel after TSA leads to functional improvement in the majority of cases with >90% postoperative healing of the subscapularis.

Finite element analysis of glenoid-sided lateralization in reverse shoulder arthroplasty.

The purpose of this study was to evaluate glenoid‐sided lateralization in reverse shoulder arthroplasty (RSA), and compare bony and prosthetic lateralization. The hypothesis was that stress and displacement would increase with progressive bony lateralization, and be lower with prosthetic lateralization. A 3D finite element analysis (FEA) was performed on a commercially available RSA prosthesis. Stress and displacement were evaluated at baseline and following 5, 10, and 15 mm of bony or prosthetic lateralization. Additional variables included glenosphere size, baseplate orientation, and peripheral screw orientation. Maximum stress for a 36 mm glenosphere without bone graft increased by 137% for the 5 mm graft, 187% for the 10 mm graft, and 196% for the 15 mm graft. Likewise, displacement progressively increased with increasing graft thickness. Stress and displacement were reduced with a smaller glenosphere, inferior tilt of the baseplate, and divergent peripheral screws. Compared to bony lateralization, stress was lower with prosthetic lateralization through the glenosphere or baseplate. Displacement with 5 mm of bony lateralization reached recommended maximal amounts for osseous integration, whereas, this level was not reached until 10–15 mm of prosthetic lateralization. Baseplate stress and displacement in an FEA model is lower with a smaller glenosphere, inferior tilt, and divergent screws. Bony lateralization increases stress and displacement to a greater degree than prosthetic lateralization. It appears that at least 10 mm of prosthetic lateralization is mechanically acceptable during RSA, but only 5 mm of bony lateralization is advised.

Biomechanical Study of a Subscapularis Repair Technique for Total Shoulder Arthroplasty

Secure subscapularis repair is an essential element of total shoulder arthroplasty. Some surgeons prefer subscapularis peel because of ease of use, but some evidence suggests that lesser tuberosity osteotomy provides better fixation. The authors developed a novel, through-implant repair technique and performed a biomechanical study of its strength with cadaveric specimens. The authors obtained 20 matched pairs of cadaveric shoulders and inserted an uncemented short-stemmed humeral prosthesis that facilitates through-implant repair in all specimens. For each cadaver, the subscapularis was repaired with lesser tuberosity osteotomy and standard suture technique on 1 side, and the contralateral subscapularis was repaired with a novel through-implant suture repair and subscapularis peel technique. Displacement of the subscapularis footprint, ultimate load to failure, and stiffness of each repair were measured and compared between fixation groups. Mean±SD displacement of the lesser tuberosity osteotomy group was 0.75±0.94 mm at 10 cycles and 2.24±2.76 mm at 500 cycles. Mean±SD load to failure was 612±185 N, and mean±SD ultimate stiffness was 119±32 N/mm. No significant differences were noted between the lesser tuberosity osteotomy group and the subscapularis peel group in mean±SD displacement at 10 cycles (1.09±1.30 mm, P=.31), mean±SD displacement at 500 cycles (2.85±2.43 mm, P=.26), mean±SD load to failure (683±274 N, P=.31), or mean±SD ultimate stiffness (117±37 N/mm, P=.88). In a biomechanical testing model, through-implant subscapularis repair provided secure fixation relative to currently accepted subscapularis repair techniques in total shoulder replacement. [Orthopedics. 2016; 39(5):e937-e943.].

Radiographic changes differ between two different short press-fit humeral stem designs in total shoulder arthroplasty

BACKGROUND The purpose of this study was to compare the radiographic changes of the humerus in the short term after total shoulder arthroplasty with two different short-stem humeral components. The hypothesis was that there would be no difference in radiographic changes or functional outcome based on component type. METHODS A retrospective review was conducted of primary total shoulder arthroplasties performed with a short press-fit humeral component. Group A included a collarless humeral stem with an oval geometry and curved stem (Ascend or Ascend Flex; Wright Medical, Memphis, TN, USA). Group B included a humeral stem with a metaphyseal collar, rectangular geometry, and straight stem (Apex; Arthrex, Inc., Naples, FL, USA). Radiographic changes and functional outcome were evaluated at a minimum of 2 years postoperatively. RESULTS There were 42 patients in group A and 35 patients in group B available for analysis. There was no difference in functional outcome between the groups. In group A, the mean total radiographic change score of the humerus was 3.9, with changes classified as low in 38% and high in 62%. In group B, the mean total radiographic change score of the humerus was 2.5, with changes classified as low in 77% and high in 23% (P < .001). Medial calcar osteolysis was present in 71% of group A compared with 28.5% of group B (P < .001). CONCLUSION At short-term follow-up, there is no difference in functional outcome or revision between 2 different humeral stem designs. However, bone adaptive changes and the rate of medial calcar osteolysis are significantly different.

Short-term clinical outcome of an anatomic short-stem humeral component in total shoulder arthroplasty

BACKGROUND Short-stem press-fit humeral components have recently been developed in an effort to preserve bone in total shoulder arthroplasty (TSA), but few studies have reported outcomes of these devices. The purpose of this study was to evaluate the short-term clinical outcomes of an anatomic short-stem humeral component in TSA. We hypothesized that the implant would lead to significant functional improvement with low rates of radiographic loosening. METHODS A multicenter retrospective review was performed of TSAs using an anatomic short-stem humeral component (Apex; Arthrex, Inc., Naples, FL, USA). The minimum follow-up was 2 years. Functional outcome was evaluated according to the American Shoulder and Elbow Surgeons score, Visual Analog Scale for pain, Single Assessment Numeric Evaluation, Simple Shoulder Test, and range of motion. A radiographic analysis was performed to evaluate component loosening. RESULTS Sixty-four patients with a mean age of 64.1 years were available for follow-up at a mean of 25 months postoperatively. There were significant improvements in the Visual Analog Scale (6 to 2; P < .001), Simple Shoulder Test (4 to 10; P < .001), Single Assessment Numeric Evaluation (32 to 84; P < .001), and American Shoulder and Elbow Surgeons (37 to 80; P < .001) scores. Forward flexion improved from 116° to 148° (P < .001), external rotation improved from 30° to 57° (P < .001), and internal rotation improved from an average spinal level of S1 to L2 (P < .001). On radiographic examination, 9% of stems were deemed at risk for loosening, but there was no gross loosening in any patient. CONCLUSIONS TSA with an anatomic press-fit short-stem humeral component is associated with significant improvements in clinical outcomes, without evidence of component loosening at short-term follow-up.

Stress shielding of the humerus in press-fit anatomic shoulder arthroplasty: review and recommendations for evaluation

Uncemented press-fit humeral stems were developed with the goal of decreasing operative time, preserving bone stock, and easing revision. In recent years, short stems and stemless humeral implants have also become available. These press-fit humeral implants have varying designs that can lead to changes in stress distribution in the proximal humerus. Such stress shielding manifests as bony adaptations and may affect long-term functional outcome and the ability to perform revision. However, current studies of humeral fixation during total shoulder arthroplasty are complicated because a variety of classification systems have been used to report findings. The purpose of this report is to review the current literature on press-fit fixation of the humeral component during total shoulder arthroplasty and propose minimum requirements for radiographic descriptions of stress shielding.

Proximal stress shielding is decreased with a short stem compared with a traditional-length stem in total shoulder arthroplasty

BACKGROUND This study compared the outcome and radiographic humeral adaptations after placement of a traditional-length (TL) or short-stem (SS) humeral component during total shoulder arthroplasty (TSA). The hypothesis was there would be no difference in outcome or radiographic adaptations. METHODS A multicenter retrospective review was performed of primary TSAs performed with a TL or SS press-fit humeral component. The stems were identical in geometry and coating, with the only variable being stem length. Functional outcome and radiographs were reviewed at a minimum of 2 years postoperatively in 58 TL stems and 56 SSs. RESULTS There were significant improvements in all range of motion and functional outcome from baseline (P < .001) but no difference between the groups (P > .05). TL stems were placed in anatomic alignment 98% of the time compared with 86% of the SS cases (P = .015), but alignment did not influence outcome. Cortical thinning was more common in the medial metaphysis with the TL stem (74%) than with the SS (50%; P = .008). Partial calcar osteolysis was seen in 31% of TL stems and in 23% of SSs (P = .348). There was no difference in loosening or shift between the 2 groups. CONCLUSION There is no difference in functional outcome at short-term follow-up between a TL stem and a SS in TSA. The pattern of radiographic adaptations may differ based on stem length. Further study is needed to evaluate the mid- to long-term differences, particularly with regard to calcar osteolysis.

Coracoid bypass procedure: surgical technique for coracoclavicular reconstruction with coracoid insufficiency.

BACKGROUND Failed acromioclavicular (AC) joint reconstruction secondary to a coracoid fracture or insufficiency of the coracoid is an uncommon but challenging clinical situation. We describe a surgical technique of revision coracoclavicular (CC) reconstruction, the coracoid bypass procedure, and report short-term results with this technique in 3 patients. METHODS In the coracoid bypass procedure, reconstruction of the CC ligaments is performed by passing a tendon graft through a surgically created bone tunnel in the scapular body (inferior to the base of the coracoid) and then fixing the graft around the clavicle or through bone tunnels in the clavicle. Three patients treated with this technique were retrospectively reviewed. RESULTS AC joint reconstruction performed for a traumatic AC joint separation failed in the 3 patients reported in this series. The previous procedures were an anatomic CC reconstruction in 2 patients and a modified Weaver-Dunn procedure in 1 patient. The coracoid fractures were detected postoperatively, and the mean interval from the index surgery to the coracoid bypass procedure was 8 months. The patients were a mean age of 44 years, and average follow-up was 21 months. At the last follow-up, all 3 patients were pain free, with full range of shoulder motion, preserved CC distance, and a stable AC joint. CONCLUSION The coracoid bypass procedure is a treatment option for CC joint reconstruction during revision AC joint surgery in the setting of a coracoid fracture or coracoid insufficiency.