Preoperative planning for accurate glenoid component positioning in reverse shoulder arthroplasty.

BACKGROUND: Glenoid component positioning in reverse shoulder arthroplasty (RSA) is challenging. Patient-specific instrumentation (PSI) has been advocated to improve accuracy, and is based on precise preoperative planning. The purpose of this study was to determine the accuracy of glenoid component positioning when only the glenoid surface is visible, compared to when the entire scapula is visible on a 3D virtual model. METHODS: CT scans of 30 arthritic shoulders were reconstructed in 3D models. Two surgeons then virtually placed a glenosphere component in the model while visualizing only the glenoid surface, in order to simulate typical intraoperative exposure ("blind 3D" surgery). One surgeon then placed the component in an ideal position while visualizing the entire scapula ("visible 3D" surgery). These two positions were then compared, and the accuracy of glenoid component positioning was assessed in terms of correction of native glenoid version and tilt, and avoidance of glenoid vault perforation. RESULTS: Mean version and tilt after "blind 3D" surgery were +1.4° (SD 8.8°) and +7.6° (SD 6°), respectively; glenoid vault perforation occurred in 17 specimens. Mean version and tilt after "visible 3D" surgery were +0.3° (SD 0.8°) and +0.1° (SD 0.5°), respectively, with glenoid vault perforation in 6 cases. "Visible 3D" surgery provided significantly better accuracy than "blind 3D" surgery (P<0.05). CONCLUSION: When the entire scapula is used as reference, accuracy is improved and glenoid vault perforation is less frequent. This type of visualization is only possible with pre-operative 3D CT planning, and may be augmented by PSI. LEVEL OF EVIDENCE: Basic science study. Level III.

Intra-protocol repeatability and inter-protocol agreement for the analysis of scapulo-humeral coordination.

Multi-center clinical trials incorporating shoulder kinematics are currently uncommon. The absence of repeatability and limits of agreement (LoA) studies between different centers employing different motion analysis protocols has led to a lack dataset compatibility. Therefore, the aim of this work was to determine the repeatability and LoA between two shoulder kinematic protocols. The first one uses a scapula tracker (ST), the International Society of Biomechanics anatomical frames and an optoelectronic measurement system, and the second uses a spine tracker, the INAIL Shoulder and Elbow Outpatient protocol (ISEO) and an inertial and magnetic measurement system. First within-protocol repeatability for each approach was assessed on a group of 23 healthy subjects and compared with the literature. Then, the between-protocol agreement was evaluated. The within-protocol repeatability was similar for the ST ([Formula: see text] = 2.35°, [Formula: see text] = 0.97°, SEM = 2.5°) and ISEO ([Formula: see text] = 2.24°, [Formula: see text] = 0.97°, SEM = 2.3°) protocols and comparable with data from published literature. The between-protocol agreement analysis showed comparable scapula medio-lateral rotation measurements for up to 120° of flexion-extension and up to 100° of scapula plane ab-adduction. Scapula protraction-retraction measurements were in agreement for a smaller range of humeral elevation. The results of this study suggest comparable repeatability for the ST and ISEO protocols and between-protocol agreement for two scapula rotations. Different thresholds for repeatability and LoA may be adapted to suit different clinical hypotheses.

The biomechanics of reverse anatomy shoulder replacement--a modelling study.

BACKGROUND: Reverse anatomy shoulder prostheses, in which a partial sphere is attached to the scapula and a socket to the humerus, have become popular for the treatment of arthritic shoulders with severe rotator cuff arthropathy. While they have been in relatively common use, their biomechanical aspects have not been fully investigated. METHODS: This study uses an adaptation of a 3D biomechanical shoulder model to describe the DELTA reverse prosthetic shoulder geometry and to investigate its properties. The muscle configuration was modified to represent the pathology and joint contact forces were computed for standardised activities.The model also uses a contact detect algorithm to record the impingement of the prosthesis with the scapula. FINDINGS: Results showed that the reverse design increases the deltoid function compensating for the dysfunctional rotator cuff muscles by providing sufficient moment arm (increased by 42%) to elevate the arm. It also restores joint stability by reversing the envelope of the joint contact forces and reacting to the increased shear forces. Despite these advantages, the model also confirms impingement and predicts bone notches from the contact of the prosthesis with the scapula border. Results indicate that optimised fixation and design alterations can reduce the problem but is difficult to eliminate it without compromising the joint stability. INTERPRETATION: The study provides a deep understanding of the function of the reverse designs highlighting their advantages in irreparable rotator cuff arthropathy but also the associated problems that compromise their use. Despite the limitations results indicate that reverse designs can be optimised to provide maximum functionality.

A framework for the definition of standardized protocols for measuring upper-extremity kinematics.

BACKGROUND: Increasing interest in upper extremity biomechanics has led to closer investigations of both segment movements and detailed joint motion. Unfortunately, conceptual and practical differences in the motion analysis protocols used up to date reduce compatibility for post data and cross validation analysis and so weaken the body of knowledge. This difficulty highlights a need for standardised protocols, each addressing a set of questions of comparable content. The aim of this work is therefore to open a discussion and propose a flexible framework to support: (1) the definition of standardised protocols, (2) a standardised description of these protocols, and (3) the formulation of general recommendations. METHODS: Proposal of a framework for the definition of standardized protocols. FINDINGS: The framework is composed by two nested flowcharts. The first defines what a motion analysis protocol is by pointing out its role in a motion analysis study. The second flowchart describes the steps to build a protocol, which requires decisions on the joints or segments to be investigated and the description of their mechanical equivalent model, the definition of the anatomical or functional coordinate frames, the choice of marker or sensor configuration and the validity of their use, the definition of the activities to be measured and the refinements that can be applied to the final measurements. Finally, general recommendations are proposed for each of the steps based on the current literature, and open issues are highlighted for future investigation and standardisation. INTERPRETATION: Standardisation of motion analysis protocols is urgent. The proposed framework can guide this process through the rationalisation of the approach.

Hyperbaric oxygen in tinnitus: influence of psychological factors on treatment results?

INTRODUCTION: The standard treatment of subjective tinnitus hardly reaches the level of placebo controls. Though the effectiveness of hyperbaric oxygenation (HBO) for subjective tinnitus has never been objectified, it is still advocated by some institutions. We analyzed the effectiveness of hyperbaric oxygen treatment in the context of accompanying factors. PATIENTS AND METHODS: We randomized 360 patients suffering from tinnitus into 2 HBO treatment protocols (group A: 2.2 bar for 60 min bottom time and group B: 2.5 bar for 60 min bottom time once a day for 15 days). All patients were asked to fill in a questionnaire (social and medical history, tinnitus characteristics, pre-HBO duration of tinnitus, prior therapy, pretreatment expectation, accompanying symptoms). A subjective assessment of the therapeutic effect was obtained. RESULTS: Twelve patients (3.3%) experienced complete remission of tinnitus, in 122 (33.9) the intensity lessened, and 44 (12.2%) had a subjectively agreeable change of noise characteristics. No change was found in 157 cases (43.6%) and 25 (6.9%) experienced deterioration. There was no statistically significant difference between groups A and B (p > 0.05). Out of 68 patients with a positive expectation of HBO effects, 60.3% stated that the tinnitus had improved whereas only 47.2 and 19%, respectively, out of patients who underwent therapy with an indifferent (n = 271) or negative expectation (n = 21) reported an improvement. The influence of subjective expectation on the outcome was statistically significant (p < 0.05). CONCLUSION: The therapeutic effects of HBO on subjective tinnitus may be substantially influenced by psychological mechanisms.

Hyperbaric oxygen (HBO2) in tinnitus: influence of psychological factors on treatment results?

UNLABELLED: HBO2 for subjective tinnitus has never been objectified, yet it is still advocated by many institutions. We analyzed the therapeutic effect of HBO2 treatment in the context of accompanying factors, especially focusing on the patients' attitude towards HBO2 prior to therapy. METHODS: 360 patients suffering from tinnitus were investigated in this study. They were randomized into 2 hyperbaric treatment protocols, one at 2.2, the other at 2.5 bar, 60 min bottom time each. All patients were asked to fill in a questionnaire (social and medical history, tinnitus characteristics, pre-HBO2 duration oftinnitus, prior therapy, pre-treatment expectation, accompanying symptoms) immediately before and one month after HBO2 treatment. The subjective impact of tinnitus on daily life was assessed using a score from 1 to 10 prior to HBO2 and one month after the treatment. RESULTS: 12 patients (3.3%) experienced complete remission of tinnitus, in 122 (33.9%) the intensity lessened, and 44 (12.2%) had a subjectively agreeable change of noise characteristics. 157 (43.6%) stated no change and 25 (6.9%) experienced deterioration. There was no statistically significant difference between the two hyperbaric protocols (p > 0.05). Out of 68 patients with positive expectation towards HBO2 therapy 60.3% stated that the tinnitus had improved whereas out of the patients who underwent therapy with indifferent (N = 271) or negative expectations (N = 21) only 47.2% and 19%, respectively, reported an improvement. The influence of both positive and negative anticipation on the outcome was statistically significant (p < 0.05). CONCLUSION: The therapeutic effects of HBO2 on subjective tinnitus might be greatly due to psychological mechanisms triggered by the attitude of the patient towards HBO2 therapy prior to the treatment.

Mechanical evaluation of mandibular defects reconstructed using osteogenic protein-1 (rhOP-1) in a sheep model: a critical analysis.

Osteoinductive bone morphogenetic proteins (BMPs) have been used extensively in experimental and clinical orthopaedic research. It is a natural progression for these growth regulators to be tested in the craniofacial region. The aim of this investigation was to analyse the mechanical properties of the sheep mandibles reconstructed using recombinant human osteogenic protein type 1 (rhOP-1). A unilateral 35 mm osteoperiosteal continuity defect was created at the parasymphyseal region of the mandible in six adult sheep. The animals were sacrificed 3 months after surgery and mechanical properties of the regenerated bone at the operated sides (OS) were compared to the corresponding bone at the non-operated side (NOS). The regenerated tissue at the OS were then submitted for histological and histomorphometric analysis. Although all the animals achieved complete bony union, a wide range of mechanical properties was found. The rhOP-1-induced bone achieved a mean of 36% of the strength of the bone at the NOS (P < 0.05). The mean value of the stiffness of the OS was 24% of the NOS (P < 0.05). While half of the samples of the OS had 'weak' mechanical properties (9-25% strength compared to NOS) and a low stiffness (6-18%), the rest showed relatively higher strength (47-63%) and were stiffer (35-47%). Unlike the NOS, the operated sides failed under tensile stresses and cracks initiated at the superior border of the mandible. The wide mechanical variations suggest that further basic bone biology research is needed to provide better understanding of the cellular and molecular events which take place during the process of osteoinduction.

[Diffuse hyperplastic oncocytosis of the parotid gland]. / Die diffuse Onkozytose der Glandula Parotidea.

BACKGROUND: Oncocytes are epithelial cells characterized by an granular, eosinophilic cytoplasma, and a centrally situated, pycnotic nucleus. These cells were first observed by Hamperl 1931 in the salivary glands. Ultrastructural studies have shown that the cytoplasma of these cells is filled with numerous large and bizarre mitochondria. The exact biological significance of oncocytes is unknown - Becker, Donath and Seifert suggest an intracellular metabolic disturbance associated with mitochondriopathy, caused by an age dependent metabolic defect. Oncocytes are not specific for the salivary glands; they are also found in the thyroid gland, parathyroid gland, liver, pancreas, esophagus and the kidney. Solitary oncocytes appear most often as incidental findings in aging salivary tissue, they are present in persons older than 70 years up to 80 %. The diffuse hyperplastic oncocytosis of the parotid gland represents an extremely rare, non-tumorous alteration of the parotid gland. Caused by an extensive metaplasia of acinic and ductal cells nearly the entire gland consists of oncocytes. Clinically it is characterized by swelling of the parotid gland. Oncocytic adenomatous hyperplasia is a different disease. It represents a multifocal oncocytic proliferation of the duct system. In contrast to diffuse oncocytosis remnants of the original salivary tissue with acini and fatty tissue are usually present between the oncocytic nodules. Typical oncocytomas may possibly develop from such oncocytic proliferation by a tendency to confluent growth. METHODS: Cases of diffuse hyperplastic oncocytosis of the parotid gland were identified by literature review. RESULTS: Worldwide diffuse hyperplastic oncocytosis of the parotid gland has been observed in 8 cases (Fig. ) as of today. PATIENT: We report and discuss the case of a 78-year-old male, who was refered to our hospital because of a painless mass of the left parotid gland. MRI showed a tumorous lesion with a diameter of about 5 cm. Lateral parotidectomy was performed. Histology revealed an extremely rare case of diffuse hyperplastic oncocytosis. There has been no recurrence of tumor after 2 years. CONCLUSIONS: Diffuse hyperplastic oncocytosis of the parotid gland is an extremely rare benign disorder, complete excision of the tumor-like lesion is curative. In literature there has been no report of recurrence, malignant transformation or metastasizing illness.

Mechanical testing of recombinant human bone morphogenetic protein-7 regenerated bone in sheep mandibles.

A new method was developed in this study for testing excised sheep mandibles as a cantilever. The method was used to determine the strength and stiffness of sheep hemi-mandibles including a 35 mm defect bridged by regenerated bone. Recombinant human bone morphogenetic protein-7 (rhBMP-7) in a bovine collagen type-I carrier was used for the bone regeneration. Initial tests on ten intact sheep mandibles confirmed that the strength, stiffness and area beneath the load-deformation curves of the right and left hemi-mandibles were not significantly different, confirming the validity of using the contra-lateral hemi-mandible as a control side. Complete bone regeneration occurred in six hemi-mandibles treated with rhBMP, but the quality and mechanical properties of the bone were very variable. The new bone in three samples contained fibrous tissue and was weaker and less stiff than the contra-lateral side (strength, 10-20 per cent; stiffness, 6-15 per cent). The other half had better-quality bone and was significantly stiffer and stronger (p < 0.05), with strength 45-63 per cent and stiffness 35-46 per cent of the contra-lateral side. Hemi-mandibles treated with collagen alone had no regenerated bone bridge suggesting that 35 mm is a critical-size bone defect.

The impact of heterozygosity for the factor V Leiden and factor II G20210A mutations on the risk of thrombosis in Greek patients.

AIM: There is growing evidence that a number of genetic risk factors predispose independently to venous thrombosis and the coexistence of defective genes is involved in the manifestation and recurrence of thrombotic events. The goal of this study was to examine the efficiency of the selection criteria for performing a genetic test for the factor V G1691A (Leiden) and factor II G20210A mutations. METHODS: Blood samples were drawn from 119 patients referred to us by their physicians. FV and prothrombin (FII) mutations were detected by polymerase chain reaction (PCR) followed by digestion with restriction endonucleases MnlI (FV), HindIII and MspI (FII). RESULTS: Patient carrier frequencies were 16.8% and 10.08% for FV Leiden and FII G20210A, respectively. Heterozygosity for FII G20210A was observed in 10.0% of FV Leiden carriers whereas FV Leiden homozygosity was noted in 1.68% of the patients. Genotype frequencies were in conformity with Hardy-Weinberg equilibrium by the chi square goodness of fit test. CONCLUSION: The obtained data provided a substantial genetic explanation of the thrombotic phenotype in approximately 25% of the patients and thus the physicians selection criteria were sufficient for genetic testing. Furthermore, coinheritance of both genetic defects were significantly associated with increased thrombosis risk and that of recurrent thrombosis.

Evidence of low-grade intravascular coagulation in patients with transvenous pacemakers.

Serum fibrin and fibrinogen degradation products (FDP) were measured in 4 groups of patients. In Group A (30 patients) FDP levels were measured before and 48-60 hours after pacemaker and transvenous electrode placement. They remained negative (less than 10 micrograms/ml) in 14, rose to greater than 10 micrograms/ml less than 40 micrograms/ml in 12, and greater than 40 micrograms/ml in 4. In 12 Group B patients undergoing the same procedure, FDP levels remained negative in 8, and rose in 4 after 24 hours and after 7 days. In 12 Group C patients studied at initial electrode and battery implantation and 3-6 months later, there were the same results in short- and long-term FDP measurements (8 negative and 4 elevated). Finally, in 14 patients with negative FDP levels who underwent battery replacement only, 3.1 to 5.2 years after their initial operation (Group D), no increase of FDP titer was seen postoperatively. Our results suggest that elevated FDP levels suggest subclinical intravenous or intracardiac thrombosis in patients with transvenous pacemakers.

Traumatic hemopericardium and chronic constrictive pericarditis.

Chronic constrictive pericarditis following traumatic hemopericardium has been reported in recent years, but it has not been reproduced experimentally in dogs. The present study attempted to produce posttraumatic constrictive pericarditis in 34 experimental animals. Hemopericardium by means of trauma to the epicardium or pericardium was produced by a sharp instrument or by the injection of autologous blood inside the pericardial sac. All animals were killed at intervals between 3 and 31 months. The animals in which hemopericardium was induced by injecting blood into the pericardial cavity showed no changes. The hemopericardium was completely resolved without noticeable residual trace. Animals having hemopericardium as a result of trauma evidenced a well-developed constrictive pericarditis that was documented clinically, hemodynamically, and histologically. These experimental findings indicate that chronic constrictive pericarditis may well be due to traumatic hemopericardium rather than to specific infection.