BACKGROUND: The currently available reverse shoulder arthroplasty (RSA) designs can be classified into medial glenoid/medial humerus (MGMH), lateral glenoid/medial humerus (LGMH), and medial glenoid/lateral humerus (MGLH) prosthesis designs. The purpose of this study was to radiologically analyze the effect of different RSA designs on humeral position following RSA. METHODS: A total of 50 patients who underwent primary RSA were retrospectively analyzed. Among 50 patients, 33 patients (group A: MGMH) underwent RSA with Aequalis system (Wright, Inc, Bloomington, MN, USA), 6 (group B: LGMH) with Aequalis system using bony increased offset, and 11 (group C: MGLH) with Aequalis Ascend Flex system. The acromiohumeral distance, acromioepiphyseal distance (AED), lateral humeral offset (LHO), LHO from the center of rotation (LHO(COR)), and deltoid length were radiologically measured to quantify the distalization and lateralization of the humerus. RESULTS: The increment in postoperative AED was 19.92 ± 3.93 mm in group A, 24.52 ± 5.25 mm in group B, and 25.97 ± 5.29 mm in group C, respectively (p=0.001). The increment in postoperative LHO was 0.13 ± 6.30 mm, 8.00 ± 12.14 mm, and 7.42 ± 6.88 mm, respectively (p=0.005). The increment in postoperative LHOCOR was 20.76 ± 6.06 mm, 22.04 ± 5.15 mm, and 28.11 ± 4.14 mm, respectively (p=0.002). CONCLUSIONS: The radiologic analysis of the effect of different RSA designs on humeral position following RSA showed significant differences in the increment in postoperative AED, LHO, and LHO(COR) between the 3 groups. Therefore, MGLH design seems to be more effective for humeral distalization and lateralization compared to original Grammont design.
Arthroplasty ; Humans ; Humerus ; Prosthesis Design ; Retrospective Studies ; Shoulder

OBJECTIVETo evaluate the short-term results of humeral head replacement for the treatment of four-part proximal humeral fractures or fracture-dislocations.

METHODSTwenty-five patients (11 male and 14 female)with four-part proximal humeral fractures or fracture-dislocations underwent humeral head replacement. The average age was 68.2 years (ranging from 56 to 77 years). All cases were followed up and evaluated the clinical results including pain, function and range of motion of shoulder with Neer scoring system.

RESULTSThe follow-up ranged from 12 to 40 months with an average time of 29.3 months. No prosthesis loosening, prosthesis dislocation, postoperative infection, nerve injury or periprosthesis fractures occurred. The results were excellent in 8 cases, good in 11 cases and fair in 6 cases. The excellent and good rate was 76% according to Neer scoring system.

CONCLUSIONReplacement of humeral head prosthesis could attain good short-term results for four-part proximal humeral fractures or fracture-dislocations. The key to improve the postoperative results is meticulous surgical techniques and appropriate correct consecutive physical therapy.

Aged ; Arthroplasty, Replacement ; methods ; Female ; Humans ; Joint Prosthesis ; Male ; Middle Aged ; Shoulder Dislocation ; surgery ; Shoulder Fractures ; surgery ; Treatment Outcome

OBJECTIVETo compare the clinical efficacies of humeral head prosthesis and internal fixation in the treatment of comminuted proximal humeral fractures.

METHODSThe clinical data were analyzed for the patients with comminuted proximal humeral fractures undergoing surgeries for humeral head replacement or open reduction plus internal fixation in our hospital between January 2002 and January 2009. Constant scores were used to determine the excellent clinical outcome rates in the two groups, and the operating time, blood loss and postoperative motor scores of the shoulder were compared.

RESULTSForty patients in the humeral head replacement group were evaluated. According to the Constant scores, excellent outcomes were achieved in 16 patients, good outcomes in 18 patients, moderate in 3 patients, and poor in 3 patients, with an excellent outcome rate of 85%. In the 40 cases receiving open reduction plus internal fixation, excellent outcomes were achieved in 11 cases, good in 13 cases, moderate in 8 cases, and poor in 8 cases, with an excellent clinical outcome rate of 60%. Compared with open reduction plus internal fixation, humeral head replacement was associated with shortened operating time, reduced blood loss and better motor function recovery of the shoulder.

CONCLUSIONSReplacement of humeral head prosthesis produces better clinical outcomes than open reduction and internal fixation in patients with comminuted proximal humeral fractures, and can promote the short-term functional recovery of the shoulder with minimal surgical complications.

Aged ; Arthroplasty, Replacement ; Female ; Fracture Fixation, Internal ; methods ; Fracture Healing ; physiology ; Fractures, Comminuted ; etiology ; surgery ; Humans ; Humerus ; surgery ; Joint Prosthesis ; Male ; Middle Aged ; Prosthesis Implantation ; Shoulder Fractures ; surgery

A 59-year-old woman who had previously undergone an anatomic left total shoulder arthroplasty presented with increasing left shoulder pain and significant reduction in motion of the left shoulder joint. No evidence of prosthetic loosening or periprosthetic fracture was detected on the radiographs or fluoroscopic arthrogram images. Dual-energy computed tomography (DECT) images revealed evidence of loosening of the glenoid component and secondary rotator cuff failure. This case illustrates how a combination of detailed clinical history, careful physical examination and DECT arthrogram evaluation may be used to identify complications of an anatomic total shoulder arthroplasty.
Arthroplasty, Replacement, Shoulder ; adverse effects ; Diagnostic Imaging ; Female ; Humans ; Middle Aged ; Osteoarthritis ; diagnosis ; surgery ; Prosthesis Design ; Prosthesis Failure ; Range of Motion, Articular ; Reoperation ; Rotator Cuff ; diagnostic imaging ; Shoulder Joint ; diagnostic imaging ; physiopathology ; surgery

PURPOSE: The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS: Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a 45degrees angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position. RESULTS: In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased. CONCLUSION: This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.
Bite Force ; Crowns ; Dental Porcelain ; Dental Prosthesis Design ; Dental Stress Analysis ; Finite Element Analysis ; Molar ; Shoulder ; Software ; Tooth ; Zirconium

The ball and socket structure of the hip joint allows a wide range of motion that is exceeded in no other joint of the body except the shoulder. At the same time, a remarkable degree of stability is provided by the close fit of the femoral head into the acetabulum and its deepening lip, the glenoid labrum, and by the support of the strongest capsular ligaments and the thickest musculature of the body. Of all the joints, the hip is most deeply situated. This relative inaccessibility increases the difficulty of diagnosing hip lesions, rendering thorough operative exposure of the joint arduous. Precise knowledge about the anatomy of the hip joint and its surrounding structures help orthopaedic surgeons diagnose and treat various diseases and trauma around the hip joint. An understanding of the biomechanics of the hip is vital to advancing the diagnosis and treatment of many pathologic conditions. Benefits from advances in hip biomechanics include the evaluation of joint function, the development of therapeutic programs for treatment of joint problems, procedures for planning reconstructive surgeries, and the design and development of total hip prostheses. Biomechanical principles also provide a valuable perspective to our understanding of the mechanism of injury to the hip, to femoroacetabular impingement, and to the etiology of degenerative hip disease.
Acetabulum ; Biomechanics ; Femoracetabular Impingement ; Head ; Hip ; Hip Joint ; Hip Prosthesis ; Joints ; Ligaments ; Lip ; Range of Motion, Articular ; Shoulder

BACKGROUND: The aim of this study was to determine if there were significant differences in glenohumeral joint morphology between North American and East Asian populations that may influence sizing and selection of shoulder arthroplasty systems. METHODS: Computed tomography reconstructions of 92 North American and 58 East Asian patients were used to perform 3-dimensional measurements. The proximal humeral position was normalized in all patients by aligning it with the scapular plane utilizing anatomic landmarks. Measurements were performed on the humerus and scapula and included coronal and axial humeral head radius, humeral neck shaft and articular arc angles, glenoid height and width, and critical shoulder angle. Glenohumeral relationships were also measured and included lateral distance to the greater tuberosity and acromion, abduction lever arm, and acromial index. Parametric and nonparametric statistical analyses were used to compare population metrics. RESULTS: East Asian glenohumeral measurements were significantly smaller for all linear metrics (p < 0.05), with the exception of acromial length, which was greater than in the North American cohort (p < 0.001). The increase in acromial length affected all measurements involving the acromion including abduction lever arms. No difference was found between the neck shaft and articular angular measurements. CONCLUSIONS: The East Asian population exhibited smaller shoulder morphometrics than their North American cohort, with the exception of an extended acromial overhang. The morphologic data can provide some additional factors to consider when choosing an optimal shoulder implant for the East Asian population, in addition to creating future designs that may better accommodate this population.
African Americans/*statistics & numerical data ; Aged ; Anthropometry ; Asian Continental Ancestry Group/*statistics & numerical data ; European Continental Ancestry Group/*statistics & numerical data ; Female ; Humans ; Male ; Prosthesis Design ; Republic of Korea/epidemiology ; Shoulder/*anatomy & histology ; Shoulder Joint/*anatomy & histology ; Shoulder Prosthesis ; United States/epidemiology

BACKGROUND: Different implant designs are utilized in reverse shoulder arthroplasty. The purpose of this systematic review was to evaluate the results of reverse shoulder arthroplasty using a traditional (Grammont) prosthesis and a lateralized prosthesis for the treatment of cuff tear arthropathy and massive irreparable rotator cuff tears. METHODS: A systematic review of the literature was performed via a search of two electronic databases. Two reviewers evaluated the quality of methodology and retrieved data from each included study. In cases where the outcomes data were similar between studies, the data were pooled using frequency-weighted mean values to generate summary outcomes. RESULTS: Thirteen studies met the inclusion and exclusion criteria. Demographics were similar between treatment groups. The frequency-weighted mean active external rotation was 24° in the traditional group and 46° in the lateralized group (p = 0.0001). Scapular notching was noted in 44.9% of patients in the traditional group compared to 5.4% of patients in the lateralized group (p = 0.0001). The rate of clinically significant glenoid loosening was 1.8% in the traditional group and 8.8% in the lateralized group (p = 0.003). CONCLUSIONS: Both the traditional Grammont and the lateralized offset reverse arthroplasty designs can improve pain and function in patients with diagnoses of cuff tear arthropathy and irreparable rotator cuff tear. While a lateralized design can result in increased active external rotation and decreased rates of scapular notching, there may be a higher rate of glenoid baseplate loosening.
Adult ; Aged ; Aged, 80 and over ; *Arthroplasty, Replacement/adverse effects/instrumentation/statistics & numerical data ; Female ; Humans ; Male ; Middle Aged ; Postoperative Complications ; Prosthesis Design ; Rotator Cuff/*surgery ; *Shoulder Prosthesis/adverse effects/statistics & numerical data ; Treatment Outcome

We developed a three-dimensional finite element model of the shoulder glenohumeral joint after shoulder arthroplasty including humerus shaft, scapular, scapular cartilage and eight muscles, while each of the muscles was simulated with 50 spring elements. To reduce the element number and improve the analytical precision, we used mixed tetrahedral and hexahedral elements in the model. We then used the model to calculate the biomechanics of the shoulder glenohumeral joint after hemiarthroplasty during humeral external rotation. Results showed that the maximum joint reaction force was 374.72 N and the maximum contact stress was 6. 573 MPa together with the contact areas at 40 degrees external rotation. These might be one of the reasons for prosthetic disarticulation, and would provide theoretical bases to prosthetic design.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Humeral Head ; anatomy & histology ; Models, Anatomic ; Prosthesis Design ; Range of Motion, Articular ; Rotation ; Shoulder Joint ; anatomy & histology

BACKGROUND: Antibiotic spacers in shoulder periprosthetic joint infection deliver antibiotics locally and provide temporary stability. The purpose of this study was to evaluate differences between stemmed and stemless spacers. METHODS: All spacers placed from 2011 to 2013 were identified. Stemless spacers were made by creating a spherical ball of cement placed in the joint space. Stemmed spacers had some portion in the humeral canal. Operative time, complications, reimplantation, reinfection, and range of motion were analyzed. RESULTS: There were 37 spacers placed: 22 were stemless and 15 were stemmed. The stemless spacer population was older (70.9 ± 7.8 years vs. 62.8 ± 8.4 years, p = 0.006). The groups had a similar percentage of each gender (stemless group, 45% male vs. stemmed group, 40% male; p = 0.742), body mass index (stemless group, 29.1 ± 6.4 kg/m² vs. stemmed group, 31.5 ± 8.3 kg/m²; p = 0.354) and Charlson Comorbidity Index (stemless group, 4.2 ± 1.2 vs. stemmed group, 4.2 ± 1.7; p = 0.958). Operative time was similar (stemless group, 127.5 ± 37.1 minutes vs. stemmed group, 130.5 ± 39.4 minutes). Two stemless group patients had self-resolving radial nerve palsies. Within the stemless group, 15 of 22 (68.2%) underwent reimplantation with 14 of 15 having forward elevation of 109°± 23°. Within the stemmed group, 12 of 15 (80.0%, p = 0.427) underwent reimplantation with 8 of 12 having forward elevation of 94°± 43° (range, 30° to 150°; p = 0.300). Two stemmed group patients had axillary nerve palsies, one of which self-resolved but the other did not. One patient sustained dislocation of reverse shoulder arthroplasty after reimplantation. One stemless group patient required an open reduction and glenosphere exchange of dislocated reverse shoulder arthroplasty at 6 weeks after reimplantation. CONCLUSIONS: Stemmed and stemless spacers had similar clinical outcomes. When analyzing all antibiotic spacers, over 70% were converted to revision arthroplasties. The results of this study do not suggest superiority of either stemmed or stemless antibiotic spacers.
Anti-Bacterial Agents ; Arthroplasty* ; Body Mass Index ; Comorbidity ; Dislocations ; Humans ; Joints ; Male ; Operative Time ; Paralysis ; Prosthesis-Related Infections ; Radial Nerve ; Range of Motion, Articular ; Replantation ; Shoulder*