Biomechanical relevance of glenoid component positioning in the reverse Delta III total shoulder prosthesis

The presence of a notch at the inferior part of the scapular neck is a common radiographic finding in patients treated with a reverse Delta III shoulder prosthesis. It is thought that this notch is a result of mechanical contact between the polyethylene cup of the humeral implant and the inferior glenoid pole during adduction of the arm. This in vitro study assessed the effect of glenoid component positioning on glenohumeral range of motion in 8 shoulder specimens. Four different positions of the glenosphere were tested: glenosphere centered on the glenoid, leaving the inferior glenoid rim uncovered (configuration A); glenosphere flush with the inferior glenoid rim (configuration B); glenosphere extending beyond the inferior glenoid rim (configuration C); and glenosphere tilted downward 15 degrees (configuration D). The respective mean adduction and abduction angles in the scapular plane were -25 degrees and 67 degrees for configuration A, -14 degrees and 68 degrees for configuration B, -1 degrees and 81 degrees for configuration C, and -9 degrees and 75 degrees for configuration D. Placing the glenosphere distally (test configuration C) significantly improved adduction and abduction angles compared with all other test configurations (P < .001).     

Comminuted periprosthetic humeral fracture after reverse shoulder prosthesis

Periprosthetic fractures represent a severe complication after joint replacement. A case of comminuted displaced humeral fracture around the stem of a SMR reverse shoulder prosthesis is reported. The patient was a 81-year-old lady who had had a total shoulder replacement 28 months previously. The surgical solution consisted of a partial revision of the modular implant with conservation not only of the glenoid component but also of the prosthetic humeral body, which was well fixed in the humeral metaphysis. The humeral stem was removed and a long uncemented revision stem was implanted providing fracture stabilisation and allowing early mobilisation.     

Comminuted periprosthetic humeral fracture after reverse shoulder prosthesis

Periprosthetic fractures represent a severe complication after joint replacement. A case of comminuted displaced humeral fracture around the stem of a SMR reverse shoulder prosthesis is reported. The patient was a 81-year-old lady who had had a total shoulder replacement 28 months previously. The surgical solution consisted of a partial revision of the modular implant with conservation not only of the glenoid component but also of the prosthetic humeral body, which was well fixed in the humeral metaphysis. The humeral stem was removed and a long uncemented revision stem was implanted providing fracture stabilisation and allowing early mobilisation.     

Evolution of the reverse total shoulder prosthesis

Over the last decade, reverse total shoulder arthroplasty has gained significant popularity due to its ability to address difficult reconstructive shoulder problems that could not be adequately treated in the past. The concept of the reverse shoulder prosthesis was introduced in the 1970s, but the initial attempts were associated with high complication and implant failure rates. The pioneering work of Paul Grammont (shifting the center of rotation medially and distally) and the development of the DELTA prosthesis have been fundamental to all subsequent reverse shoulder arthroplasty systems. These semiconstrained prostheses utilize the deltoid to improve function and stability of the shoulder joint by coupling a convex glenoid with a concave humeral component. Modern generations of reverse shoulder prosthesis continue to evolve on the fundamentals of Grammont. Though results of these new prosthesis demonstrate promising outcomes, many controversies and challenges continue to be refined. An historical review of the evolution of reverse shoulder arthroplasty is presented, as well as the currently expanding indications for its application.     

The use of the reverse shoulder prosthesis for the treatment of failed hemiarthroplasty for proximal humeral fracture

BACKGROUND: Humeral 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. METHODS: Over 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. RESULTS: The 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. CONCLUSIONS: The 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.     

肩关节置换术中肱骨假体低置的疗效分析

目的探讨肱骨假体低置在肩关节置换术患者中的疗效。方法对12例肱骨近端三、四部骨折的老年患者行半肩关节置换术治疗,术中采用假体低置使肱骨大结节与肱骨近端重叠方式固定,并对其进行5～36个月随访,参照美国肩肘关节医师学会肩关节评分系统（ASES）进行功能评分。结果 12例患者均无明显疼痛,无肩关节脱位或不稳的情况出现,患肩上举、内旋、外旋、外展活动总体满意。ASES功能评分平均为81分,评定为满意。结论肱骨假体低置对肩关节置换术患者的早期功能及稳定性影响不大。     

The reverse shoulder prosthesis for primary and secondary treatment of proximal humeral fractures: a case report

Humeral head fractures are very common among elderly people, often requiring shoulder arthroplasty. One requirement for good function after shoulder arthroplasty is an intact or at least reparable rotator cuff. In patients with multifractured and or osteoporotic tuberosities, refixation leads to the potential risk of redislocation and resorption of the tuberosities or coexisting irreparable rotator cuff tears lead to a high failure rate after implantation of traditional fracture prosthesis, whereas the reverse shoulder arthroplasty may provide better outcome. Here we report of a 79-year-old woman, who fractured both humeral heads at different times. Her right side was treated with a fracture prosthesis, which had to be converted after 2 years to a reverse shoulder prosthesis. Because of coexisting irreversible rotator cuff tear accompanying the second humeral head fracture on her left side, this patient was primarily treated with a reverse shoulder prosthesis. During the most recent follow up, 33 months after reverse shoulder arthroplasty on the left side and 39 months on the right side, the age- and gender-adapted constant score was 88 compared to 59 on the right side. The primary or secondary implantation of the reverse shoulder prosthesis in proximal humeral fractures has to be planned carefully, since long-term results are still lacking and treatment options after failed reverse shoulder arthroplasty are few. Generally, primary implantation of traditional fracture prosthesis is indicated in most cases of humeral head fractures; but in carefully selected cases primary reverse shoulder arthroplasty may be superior and lead to better outcome. Therefore, future research should be conducted to find criteria where the reverse shoulder arthroplasty is indicated as first line treatment of proximal humeral head fractures in elderly patients.     

半肩假体置换治疗肱骨近端复杂性骨折的应用研究

目的探讨半肩假体置换治疗肱骨近端NeerⅢ和NeerⅣ骨折的临床疗效及手术要点。方法从2005年9月～2010年10月,本组收治了33例肱骨近端复杂骨折的患者,男14例,女19例;年龄62～80岁,平均73.7岁;左侧11例,右侧22例,NeerⅢ13例,NeerⅣ20例,行LINK半肩假体置换治疗。术后应用改良的半肩关节置换评分系统（scoring system-modification for hemiarthroplasty,SSMH）评分和美国肩肘医师评分（American Shoulder and Elbow Surgeon Score,ASES）评价治疗效果。结果 33例患者中均得到随访,随访时间6～55个月,平均28个月。SSMH评分术后1周平均评分14.5分,末次随访（所有患者随访时间均〉6个月）平均评分25.6分,ASES评分术后1周平均评分45分,末次随访平均为84分。结论半肩关节置换是一种治疗肱骨近端复杂性骨折的有效方法,肩袖重建方式、假体与关节盂吻合度、术后功能锻炼是影响疗效的主要因素。     

Optimal glenoid component inclination in reverse shoulder arthroplasty. How to improve implant stability

Background

Total shoulder arthroplasty infections are rare, depending on the use of antibiotic prophylaxis, the local blood supply, the axial load gradient and the proximal location of the shoulder. The purpose of this study was to evaluate the results of treatment for infections in total shoulder arthroplasty and septic arthritis using a preformed antibiotic-loaded spacer.

Materials and methods

Seven shoulders in as many patients were treated for infected arthroplasty or septic arthritis without previous surgery. A preformed antibiotic-loaded spacer was always applied. Patients were evaluated at the final follow-up with the Constant Score (CS), the Secec Elbow Score (SES), and the American Shoulder and Elbow Society Score (ASESS).

Results

The mean follow-up was 40, 71 months after spacer implant. Infection was always confirmed preoperatively by the leukocyte and neutrophil counts in the aspirated synovial fluid, and intra-operative biopsy and pathologic analysis. Positive bacterial cultures were found in 5 cases: 3 MRSA and 2 Staphylococcus epidermidis. The mean SES increased from 34.43 before spacer implant to 77.29 at final follow-up, ASESS ranged from 14.86 to 21.14, and CS from 40.28 to 79.14.

Conclusion

A preformed antibiotic-loaded spacer is intended to release gentamicin alone, but we can consider adding vancomycin to increase antibiotic spectrum. An early diagnosis and an immediate treatment can prevent a persistent infection and severe soft-tissue damage. The use of a preformed antibiotic spacer allows maintaining joint function at the intermediate stage in two-stage treatment.