Hemiarthroplasties: the choice of prosthetic material causes different levels of damage in the articular cartilage.

BACKGROUND: Hemiarthroplasty has clear advantages over alternative procedures and is used in 20% of all shoulder joint replacements. Because of cartilage wear, the clinical outcome of hemiarthroplasty is unreliable and controversial. This paper suggests that the optimal choice of prosthetic material may reduce cartilage degeneration and improve the reliability of the procedure. The specific objectives were to assess 3 materials and assess how the severity of arthritis might affect the choice of prosthetic material. METHODS: A CoCr alloy, an AL2O3 ceramic, and a polycarbonate urethane polymer (PCU) were mechanically tested against 5 levels of human osteoarthritic cartilage (from intact to severely arthritic, n = 45). A high friction coefficient, a decrease in Young's modulus, an increase in permeability, a decrease in relaxation time, an increase in surface roughness, and a disrupted appearance of the cartilage after testing were used as measures of cartilage damage. The biomaterial that caused minimal cartilage damage was defined as superior. RESULTS: The CoCr caused the most damage. This was followed by the AL2O3 ceramic, whereas the PCU caused the least amount of damage. Although the degree of arthritis had an effect on the results, it did not change the trend that CoCr performed worst and PCU the best. DISCUSSION AND CONCLUSION: This study indicates that ceramic implants may be a better choice than metals, and the articulating surface should be as smooth as possible. Although our results indicate that the degree of arthritis should not affect the choice of prosthetic material, this suggestion needs to be further investigated.

Development and ex-vivo assessment of a novel patient specific guide and instrumentation system for minimally invasive total shoulder arthroplasty.

OBJECTIVE: To develop and assess a novel guidance technique and instrumentation system for minimally invasive short-stemmed total shoulder arthroplasty that will help to reduce the complications associated with traditional open replacement such as poor muscle healing and neurovascular injury. We have answered key questions about the developed system including (1) can novel patient-specific guides be accurately registered and used within a minimally invasive environment?; (2) can accuracy similar to traditional techniques be achieved? METHODS: A novel intra-articular patient-specific guide was developed for use with a new minimally invasive posterior surgical approach that guides bone preparation without requiring muscle resection or joint dislocation. Additionally, a novel set of instruments were developed to enable bone preparation within the minimally invasive environment. The full procedure was evaluated in six cadaveric shoulders, using digitizations to assess accuracy of each step. RESULTS: Patient-specific guide registration accuracy in 3D translation was 2.2±1.2mm (RMSE±1 SD; p = 0.007) for the humeral component and 2.7±0.7mm (p<0.001) for the scapula component. Final implantation accuracy was 2.9±3.0mm (p = 0.066) in translation and 5.7-6.8±2.2-4.0° (0.001

Early simultaneous bilateral total hip arthroplasty for the management of bilateral acetabular fracture in an elderly patient.

Bilateral acetabular fractures in elderly patients due to seizures are very rare and management is a challenge. The standard treatment for acetabular fracture, open reduction with internal fixation, is not recommended for the elderly because of poor bone quality and the need for bed rest. In the acute phase, total hip arthroplasty may be the best treatment option because it allows early mobilization and avoids bed rest complications. We report the case of a 76-year-old man with a bilateral comminuted acetabular fractures and a left fracture dislocation of the shoulder, treated by immediate shoulder arthroplasty and a one-stage bilateral total hip arthroplasty procedure at 3 weeks, with a good result at 1-year follow-up.

Osteosarcoma after the age of fifty: A clinicopathological study.

INTRODUCTION: Osteosarcoma, a primary malignant bone tumor, has a well-recognised double peak of incidence in early adolescence and after 50 years. This study investigates the clinical features and prognostic factors of patients older than 50 years with osteosarcoma. MATERIEL AND METHODS: From January 2000 to December 2012, in one bone tumor reference center, 32 patients aged more than 50 years at the diagnosis (mean age: 62.4 years (50-85), sex ratio: 13 males, 19 females) diagnosed with osteosarcoma were included. Patients younger than 50 years at diagnosis or with a non-histologically proved osteosarcoma were excluded. For each patient, we registered medical history, tumor location, systemic and local extension, treatment, and survival. RESULTS: 62% were located in the extremities and 28% in the axial skeleton. 6 were secondary sarcomas. Mean delay between first symptoms and biopsy was 7.4 months (range from 0 to 28 months). Ten patients had a systemic osteosarcoma with one or more pulmonary metastases. Six patients were treated with palliative care (18.8%). Eighteen patients received neodajuvant chemotherapy, sixteen of them received postoperative chemotherapy. Twenty-five patients had surgery. Postoperative complications were reported in eight cases (25%). Overall survival for all 31 patients was 25% at 5 years and 6.2% at 10 years. Survival without metastases was 15.6% at 5 years and nil at 10 years. Median survival time for the 22 localised osteosarcoma patients was 4 years (0.9-12.6) versus 1.2 years (0.3-12.3) for the 10 systemic osteosarcoma patients (p = 0.01). CONCLUSION: Metastases at diagnosis, age, axial location are worse prognostic for survival.

Dynamic Three-Dimensional Shoulder Mri during Active Motion for Investigation of Rotator Cuff Diseases.

BACKGROUND: MRI is the standard methodology in diagnosis of rotator cuff diseases. However, many patients continue to have pain despite treatment, and MRI of a static unloaded shoulder seems insufficient for best diagnosis and treatment. This study evaluated if Dynamic MRI provides novel kinematic data that can be used to improve the understanding, diagnosis and best treatment of rotator cuff diseases. METHODS: Dynamic MRI provided real-time 3D image series and was used to measure changes in the width of subacromial space, superior-inferior translation and anterior-posterior translation of the humeral head relative to the glenoid during active abduction. These measures were investigated for consistency with the rotator cuff diseases classifications from standard MRI. RESULTS: The study included: 4 shoulders with massive rotator cuff tears, 5 shoulders with an isolated full-thickness supraspinatus tear, 5 shoulders with tendinopathy and 6 normal shoulders. A change in the width of subacromial space greater than 4mm differentiated between rotator cuff diseases with tendon tears (massive cuff tears and supraspinatus tear) and without tears (tendinopathy) (p = 0.012). The range of the superior-inferior translation was higher in the massive cuff tears group (6.4mm) than in normals (3.4mm) (p = 0.02). The range of the anterior-posterior translation was higher in the massive cuff tears (9.2 mm) and supraspinatus tear (9.3 mm) shoulders compared to normals (3.5mm) and tendinopathy (4.8mm) shoulders (p = 0.05). CONCLUSION: The Dynamic MRI enabled a novel measure; 'Looseness', i.e. the translation of the humeral head on the glenoid during an abduction cycle. Looseness was better able at differentiating different forms of rotator cuff disease than a simple static measure of relative glenohumeral position.