Elbow hemiarthroplasty for acute distal humeral fractures and their sequelae: medium- and long-term follow-up of 41 cases.

BACKGROUND: The earliest distal humeral hemiarthroplasty (or elbow hemiarthroplasty [EHA]) implants, which date back to the late 1940s, were performed in patients with severe elbow joint injuries as an alternative to arthrodesis. After some clinical reports and case studies with a short follow-up, published in the 1990s, a new "anatomically convertible" EHA model was introduced in 2005 and became a common surgical option to treat complex elbow fractures and their sequelae. We describe the mid- and long-term outcomes of EHA performed to treat acute intra-articular fractures or their sequelae. METHODS: From 2006 to 2017, 51 patients underwent EHA for acute intra-articular fractures or their sequelae. A total number of 41 patients (80.5% female) with a minimum follow-up of 2 years, 24 with acute lesions and 17 with sequelae, were identified retrospectively. Clinical evaluation was according to the Disabilities of the Arm, Shoulder, and Hand (DASH) score (subjective), and the Oxford Elbow Score (OES) and Mayo Elbow Performance Score (MEPS) (objective). Radiographic follow-up was with standard radiographs. RESULTS: Mean follow-up was 92.2 months (range, 24-151). Mean patient age at surgery was 62.8 years (range, 45-81). The mean MEPS was 87.1 points, with excellent results in 26 cases, good results in 9 cases, fair in 2, and poor results in 4. The mean DASH score was 15.9 and the mean OES was 40.5, with satisfactory results in 30 cases. Twenty patients experienced complications and 2 required revision surgery. DISCUSSION: EHA is a valuable surgical option in selected patients with comminuted distal humeral joint fractures that cannot be reconstructed with stable fixation and in those with malunion of the articular surface of the humerus. EHA offers potential advantages, especially in active elderly patients and in those aged less than 70 years. It is essential to achieve joint stability, restoring medial and lateral ligament function besides the integrity of the coronoid process. An intact olecranon surface without signs of degenerative changes is also critical for EHA success. CONCLUSION: Our mid- and long-term experience with EHA is favorable, with a high proportion of satisfactory results and long survival rates for both lesion types. In selected patients with acute and post-traumatic injuries, EHA is a valuable surgical option.

Vascular Supply and Bone Marrow Concentrate for the Improvement of Allograft in Bone Defects: A Comparative In Vivo Study.

BACKGROUND: Surgical repair of critical-sized bone defects still remains a big challenge in orthopedic surgery. Biological enhancement, such as growth factors or cells, can stimulate a better outcome in bone regeneration driven by well-established treatments such as allogenic bone graft. However, despite the surgical options available, correct healing can be slowed down or compromised by insufficient vascular supply to the injured site. MATERIALS AND METHODS: In this pilot study, critical size bone defects in rabbit radius were treated with allograft bone, in combination with vascular bundle and autologous bone marrow concentrate seeded onto a commercial collagen scaffold. Microtomographical, histological and immunohistochemical assessments were performed to evaluate allograft integration and bone regeneration. RESULTS: Results showed that the surgical deviation of vascular bundle in the bone graft, regardless from the addition of bone marrow concentrate, promote the onset of healing process at short experimental times (8 wk) in comparison with the other groups, enhancing graft integration. CONCLUSION: The surgical procedure tested stimulates bone healing at early times, preserving native bone architecture, and can be easily combined with biological adjuvant.

Diagnosis and treatment of acute Essex-Lopresti injury: focus on terminology and review of literature.

BACKGROUND: Acute Essex-Lopresti injury is a rare and disabling condition of longitudinal instability of the forearm. When early diagnosed, patients report better outcomes with higher functional recovery. Aim of this study is to focus on the different lesion patterns causing forearm instability, reviewing literature and the cases treated by the Authors and to propose a new terminology for their identification. METHODS: Five patients affected by acute Essex-Lopresti injury have been enrolled for this study. ELI was caused in two patients by bike fall, two cases by road traffic accident and one patient by fall while walking. A literature search was performed using Ovid Medline, Ovid Embase, Scopus and Cochrane Library and the Medical Subject Headings vocabulary. The search was limited to English language literature. 42 articles were evaluated, and finally four papers were considered for the review. RESULTS: All patients were operated in acute setting with radial head replacement and different combinations of interosseous membrane reconstruction and distal radio-ulnar joint stabilization. Patients were followed for a mean of 15 months: a consistent improvement of clinical results were observed, reporting a mean MEPS of 92 and a mean MMWS of 90.8. One case complained persistent wrist pain associated to DRUJ discrepancy of 3 mm and underwent ulnar shortening osteotomy nine months after surgery, with good results. DISCUSSION: The clinical studies present in literature reported similar results, highlighting as patients properly diagnosed and treated in acute setting report better results than patients operated after four weeks. In this study, the definitions of "Acute Engaged" and "Undetected at Imminent Evolution" Essex-Lopresti injury are proposed, in order to underline the necessity to carefully investigate the anatomical and radiological features in order to perform an early and proper surgical treatment. CONCLUSIONS: Following the observations, the definitions of "Acute Engaged" and "Undetected at Imminent Evolution" injuries are proposed to distinguish between evident cases and more insidious settings, with necessity of carefully investigate the anatomical and radiological features in order to address patients to an early and proper surgical treatment.

Effect of trochleocapitellar index on adult patient-reported outcomes after noncomminuted intra-articular distal humeral fractures.

BACKGROUND: Anatomic surgical reduction of intra-articular fractures of the distal humerus is important to achieve the best long-term outcomes and prevent post-traumatic arthritis. In this study we compared the radiographic reduction using the trochleocapitellar index. We also correlated the trochleocapitellar index to the functional outcomes next to the comparison of the triceps brachii lifting approach and olecranon osteotomy approach, 2 common approaches for distal humeral fractures. METHODS: From January 2006 to June 2016, patients with elbow fractures were registered in 4 centers. The trochleocapitellar index, a ratio between the angle of the capitellum and the trochlea to the midline of the distal humerus on anterior-posterior radiographs, was calculated for included patients. Functional outcomes were measured using the Oxford Elbow Score and the Mayo Elbow Performance Score. Bone healing was measured using radiographic union scoring. RESULTS: There were 86 patients enrolled: 46 in the olecranon osteotomy group and 40 in the triceps lifting group. Functional outcomes and bone healing did not differ between the approaches. Functional results had a medium correlation with the trochleocapitellar index, which did not differ between the 2 approaches (olecranon osteotomy group, κ = 0.56; triceps lifting group, κ = 0.57; P = .7932). CONCLUSIONS: The trochleocapitellar index has a moderate predictive value on the functional results after 12 months after open reduction and internal fixation of intra-articular distal humeral factures. There is no difference in reduction, as measured by trochlear index and functional outcome scores, between the olecranon osteotomy approach and the triceps brachii lifting approach groups.

Grafting and fixation of proximal humeral aseptic non union: a prospective case series.

BACKGROUND: Fractures of the proximal part of the humerus represent almost 4-5% of all fractures. The rate of non union is estimated to be 1.1 to 10%. Non union, displacement, and fixation failure can be hazardous complications for these injuries. The purpose of our study was to evaluate the outcomes of plate and bone strut allograft with bone chips grafting augmentation in the management of proximal humeral aseptic non union. METHODS: We treated 16 aseptic non union proximal humeral fractures by the medial humeral shaft bone strut allograft and lateral plate and screws with bone chips grafting. The patients' ages were between 55 and 70 years. The chosen criteria to evaluate the group during the clinical and radiological follow-up were the quality of life measured by The Short Form (12) Health Survey (SF-12), shoulder function and related quality of life measured by the Constant Shoulder Score (CSS) compared with healthy side, bone healing measured by X-rays, and postoperative complications. The follow-up was perfor med with clinical and radiographic controls at 1, 3, 6 and 12 months. Surgical time and international units of red blood cells transfused were also calculated. The evaluation endpoint was set at 12 months. RESULTS: The X-rays bone healing occurred in our group on average of 126.4 days after surgery. The surgical time and blood loss were consistent with standard surgical procedures. The quality of life and functional recovery were excellent after plate and bone strut allograft. CONCLUSIONS: Surgical techniques that increase mechanical stability, while incorporating bone biology, are effective aids for treating problematic fractural patterns.

Coronoid reconstruction with an osteochondral radial head graft.

BACKGROUND: Chronic coronoid deficiency can occur subsequent to coronoid fracture malunion/nonunion or to coronoid hypoplasia or dysplasia resulting from injury during development. Several surgical options have been described to treat this difficult condition, but results are equivocal. We hypothesized that a modified coronoid reconstruction using a radial head osteochondral graft could restore elbow stability and congruity and that a technique involving rigid internal fixation would promote graft union. METHODS: The coronoid was reconstructed using an osteochondral fragment from a frozen allograft radial head in 3 young women affected by complex post-traumatic elbow instability and incongruity resulting from coronoid deficiency. To promote bone healing, the fragment was kept as large as could be fitted in place, the cut surface compressed onto the remaining coronoid was as large as possible, the medial portion of the radial head (containing dense bone) was used, and 3 lag screws were inserted in different directions. RESULTS: At a mean follow-up of 26 months, all 3 patients achieved a painless, congruent stable joint with a functional range of motion. Computed tomography scans performed 3 months after surgery showed complete union of the graft in all the patients. Each patient rated herself as "almost normal" or "greatly improved" on the Summary Outcome Determination scale. CONCLUSION: Coronoid reconstruction with a radial head osteochondral allograft was successful in restoring stability and function in chronically unstable elbows with coronoid deficiency. Strong fixation using a large segment of the medial radial head achieved rapid graft healing.

Total elbow arthroplasty in distal humeral nonunion: clinical and radiographic evaluation after a minimum follow-up of three years.

BACKGROUND: Total elbow arthroplasties (TEAs) are usually indicated in chronic inflammatory arthropathies. This procedure has also recently been used in complex distal humeral fractures and nonunions in selected patients. This study analyzed the clinical and radiographic outcomes in patients treated for nonunions around the elbow region with a minimum follow-up of 3 years. METHODS: Between May 2002 and June 2012, 20 patients affected with distal humeral nonunions were treated with TEA. All patients were assessed clinically using the Mayo Elbow Performance Score and radiographically to evaluate the positioning of the prosthetic components and signs of loosening. Statistical analyses were performed to investigate the presence of clinical and radiographic variables as predictive factors of poor functional outcomes. RESULTS: The Mayo Elbow Performance Score of the affected arm improved significantly between the preoperative period and follow-up. Results were good or excellent in 90% of the patients even if a high rate of complications (30%) was encountered. The development of complications after surgery and stages II, III, and IV radiolucency, according to the Morrey criteria, were predictive factors of poor outcomes. CONCLUSIONS: According to the satisfactory results observed in this study, TEA could be indicated in selected patients aged older than 70 years with low functional demands and affected with distal humeral nonunions in which obtaining a stable fixation is difficult.

Treatment of osteoid osteoma of the elbow by radiofrequency thermal ablation.

BACKGROUND: This article presents the experience at the Rizzoli Orthopaedic Institute in the treatment of intracapsular osteoid osteoma (OO) of the elbow by computed tomography-guided percutaneous radiofrequency thermal ablation (RFA). MATERIALS AND METHODS: Our team performed more than 800 RFA procedures to treat OO up to 2010. In 27 cases, the lesion site was the articular area of the elbow (humerus in 13 cases, ulna in 13, and radius in 1). These patients were reviewed and assessed for eradication rate, incidence of complications, and functional results measured by the Mayo Elbow Performance Score. The outcome was evaluated after a mean follow-up period of 67.4 ± 35.3 months (range, 24-128 months). RESULTS: The mean duration of symptoms at the time of diagnosis was 31.0 ± 19.8 months (range, 5-72 months). All patients complained about pain, and in 24 of 27 cases (88.8%), the joint function was significantly impaired by the presence of OO (pretreatment score, 54.8). After RFA, the Mayo Elbow Performance Score improved by a mean of 37.7 ± 14.8 points, with 25 of 27 patients (92.5%) scoring 90 to 100 points at final follow-up. OO recurred in only 1 patient (3.7%), 5 months after the procedure. However, this was successfully retreated by RFA. No adverse effects were observed, and all patients were free of disease at the final follow-up. DISCUSSION: The RFA procedure can be technically challenging in difficult sites such as the elbow joint. The low invasiveness of RFA compared with traditional surgery allows excellent functional recovery. RFA of elbow OO is effective and safe, and it should be considered the first-choice treatment for this disease.

[Management of the worker affected by shoulder pathology]. / Gestione del lavoratore affetto da patologie della spalla.

Shoulder disorders due to overexertion include joint and soft tissues chronic conditions and are an important cause of disability. Shoulder pain is one of the most common musculoskeletal disorders and has been associated to manual handling of heavy loads, high repetition jobs, exposure to hand-arm vibration and to overhead activities. Diagnosis of shoulder disorders is primarily based on clinical examination; selected cases should be referred to an orthopedic specialist and to imaging. Return to normal activities should be encouraged.

Response of human chondrocytes and mesenchymal stromal cells to a decellularized human dermis.

BACKGROUND: Although progress has been made in the treatment of articular cartilage lesions, they are still a major challenge because current techniques do not provide satisfactory long-term outcomes. Tissue engineering and the use of functional biomaterials might be an alternative regenerative strategy and fulfill clinical needs. Decellularized extracellular matrices have generated interest as functional biologic scaffolds, but there are few studies on cartilage regeneration. The aim of this study was to evaluate in vitro the biological influence of a newly developed decellularized human dermal extracellular matrix on two human primary cultures. METHODS: Normal human articular chondrocytes (NHAC-kn) and human mesenchymal stromal cells (hMSC) from healthy donors were seeded in polystyrene wells as controls (CTR), and on decellularized human dermis batches (HDM_derm) for 7 and 14 days. Cellular proliferation and differentiation, and anabolic and catabolic synthetic activity were quantified at each experimental time. Histology and scanning electron microscopy were used to evaluate morphology and ultrastructure. RESULTS: Both cell cultures had a similar proliferation rate that increased significantly (p < 0.0005) at 14 days. In comparison with CTR, at 14 days NHAC-kn enhanced procollagen type II (CPII, p < 0.05) and aggrecan synthesis (p < 0.0005), whereas hMSC significantly enhanced aggrecan synthesis (p < 0.0005) and transforming growth factor-beta1 release (TGF-ß1, p < 0.0005) at both experimental times. Neither inflammatory stimulus nor catabolic activity induction was observed. By comparing data of the two primary cells, NHAC-kn synthesized significantly more CPII than did hMSC at both experimental times (p < 0.005), whereas hMSC synthesized more aggrecan at 7 days (p < 0.005) and TGF-ß1 at both experimental times than did NHAC-kn (p < 0.005). CONCLUSIONS: The results obtained showed that in in vitro conditions HDM_derm behaves as a suitable scaffold for the growth of both well-differentiated chondrocytes and undifferentiated mesenchymal cells, thus ensuring a biocompatible and bioactive substrate. Further studies are mandatory to test the use of HDM_derm with tissue engineering to assess its therapeutic and functional effectiveness in cartilage regeneration.

Elbow hemiarthroplasty in distal humeral fractures: Indication, surgical technique and results.

The surgical management of distal humerus fractures in adults generally consists in open reduction internal fixation (ORIF) or total elbow arthroplasty (TEA). Hemi humeral hemiarthroplasty (EHA) is a treatment option for unreconstructable intra-articular distal humerus fractures. It is a reasonable option in patients over the fifth decade and its potential advantages are to eliminate the complications related to the ulnar component such as wear of the hinge (busching wear) or the aspetic loosening of the ulnar component. The potential disadvantages are the risk of instability with the possibility of a wear and progressive joint osteoarthrosis. The aims of this manuscript are to evaluate the indications in which we used the EHA, analyzing the correct surgical technique and describe the outcomes in medium and long-term follow-ups. Between 2006 and 2019, we performed 51 EHAs at the Hesperia Hospital in Modena and at the Rizzoli Orthopedic Institute. Taking into consideration only the cases of acute fractures, 27 patients (27 elbows) with a minimum follow-up of 12 months were identified. The patient's mean age at the time of surgery was 64 years old (range from 45 to 78 years old) and they were 78% female (21 out of 27). The Latitude Tornier implant was used in all the patients of our group. The mean MEPS was 89.3 points (from 50 to 100 pts) with excellent results in 19 patients, good in 5, one fair and 2 poor;the mean DASH was 12.6 (from 3.3 to 45.8); the mean OES was 42.3 (from 22 to 47). Complications, were found in 12 patients and any patients required a TEA conversion. Distal humerus hemiarthroplasty from our experience is a good option for the surgical management of unrecostructible distal humeral fractures in selected patients. It is important to perform a precise surgical technique; preserve the triceps insertion, preserve or repair the collateral ligaments, fix the condylar bones implant the prosthesis at the correct size, depth and rotation. The majority of the complication that we observed are related to the stiffness and not to the progressive degenerative changes of the articular surface.

Unstable lesions of the forearm: Terminology, evaluative score and synoptic table.

The term "unstable lesions of the forearm" (ULF) was born to more easily describe how a partial or complete instability of the forearm unit might occur due to a traumatic loss of the transverse or longitudinal connection between the radius and ulna. For such an alteration to occur, at least two of the three main osteoligamentous locks (proximal, middle and distal) must be interrupted, often in association with a radial and/or ulnar fracture. Examining the historical patterns (Monteggia, Galeazzi, Essex-Lopresti and criss-cross lesions) and variants described in the literature, out of a total of 586 recorded interventions for forearm trauma, two elbow teams and one wrist team selected 75 cases of ULF. The aim was to describe the instability depending on its clinical and radiographic features, together with the anatomopathological evolution of the lesions based on the time of diagnosis and treatment. The clinical results, evaluated using a new score (FIPS) the Forearm Italian Performance, revealed a correlation between earlier diagnosis and treatment and a better score. The authors suggest a synoptic table that describes 1) the type of instability (proximal transverse, distal transverse, longitudinal and transverse, proximal and distal transverse), 2) classic patterns and variants with characteristic lesions and evolution over time (acute, chronic dynamic, chronic static) and 3) the three forearm constraints and segmental involvement of radius and/or ulna using an alphanumeric classification. Finally, some generic surgical suggestions are proposed.

Choice of treatments of the coronal shear fractures of the humerus. A national survey of Italian AO members.

INTRODUCTION: Coronal shear fractures of the distal humerus are uncommon injuries representing 6% of distal humeral fractures. There is no univocal consensus about the correct management of this type of fracture. A national survey was conducted to gain more insight into the current classification, diagnosis and treatment of coronal shear fractures in Italy. MATERIALS AND METHODS: A postal survey was sent to all AO Italian members including residency orthopaedic surgeons. The survey consisted of general questions about personal experience in the management of these fractures: types of classification systems used, surgical approaches, treatment options and rehabilitation programs. RESULTS: 114 orthopaedic surgeons answered a 13-items questionnaire. The most used classification system was AO/OTA (72,8%). Independent screws and if necessary plates were the most answered regarding surgical treatment (81,6%). The most encountered post-surgical complication was stiffening of the elbow (81,6%). CONCLUSION: An algorithm of treatment has been proposed. To better classify coronal shear fractures, the authors recommended the integration of two classification systems: AO and Dubberley classifications. In the case of posterior wall comminution, a Kocher extensile approach is recommended, otherwise, if a posterior wall is intact, Kocher or Kaplan approach can be used. The posterior transolecranic approach can be reserved to Dubberley type III or AO 13B3.3. The best treatment choice is represented by independent screws and plates placed according to fracture patterns while arthroplasty is indicated when a stable ORIF is not possible. Mobilization is postponed for about 2 weeks.

Decellularized human dermis to treat massive rotator cuff tears: in vitro evaluations.

Interest is increasing in biological scaffolds for tissue regeneration such as extracellular matrix membranes, developed through soft tissue decellularization. Extracellular matrix membranes were developed to heal different tendon and soft tissue lesions that are very frequent in the general population with high health-care costs and patient morbidity. The aim of this research was to evaluate a human dermal matrix (HDM) decellularized by a chemico-physical method. A primary culture of rat tenocytes was performed: tenocytes were seeded on HDM samples and on polystyrene wells as controls (CTR). Cell viability and synthetic activity were evaluated at 3 and 7 days. An in vitro microwound model was used to evaluate HDM bioactivity: after tenocyte expansion, artificial wounds were created, HDM extracts were added, and closure time and decorin synthesis were monitored histomorphometrically at 1, 4, 24, and 72 hr. A significant higher amount of collagen I was observed when cells were cultured on HDM in comparison with that on CTR (3 days: p < 0.0001; 7 days: p < 0.05). In HDM group, fibronectin synthesis was significantly higher at both experimental times (p < 0.0001). At 3 days, proteoglycans and transforming growth factor-ß1 releases were significantly higher on HDM (p < 0.0001 and p < 0.005, respectively). The artificial microwound closure time and decorin expression were significantly enhanced by the addition of 50% HDM extract (p < 0.05). In vitro data showed that the decellularization technique enabled the development of a matrix with adequate biological and biomechanical properties.

Computer-Aided Planning and 3D-Printed Surgical Guide in Patients with Extreme Cubitus Varus Deformity: A Report of 2 Cases.

CASE: We describe 2 patients with extreme triplanar cubitus varus deformity, treated with step-cut corrective virtually planned osteotomies and performed with custom-made surgical guides. The surgery was simulated on the patients' bone 3D-printed model to verify the effectiveness of the surgical plans. At a medium 21-month follow-up after surgery, in both patients, clinical and radiological results were fully satisfactory, and no complications have been reported. CONCLUSION: The precision of computer-aided surgical planning and custom-made surgical guides allow to perform reproducible and relatively safe surgeries even in extreme deformities where the surgical complexity could discourage attempts at surgical correction.

Open Reduction and Internal Fixation Using Double Plating with Biological and Artificial Bone Grafting of Aseptic Non-unions of the Distal Humerus: Clinical Results.

AIM: Intra-articular non-union of fractures is an uncommon but complex problem because in general, it is characterised by marked instability, pain, strength loss and significant functional limitation. The aim of this study is to report our prospective medium-term outcomes of the treatment of intra-articular, distal humeral aseptic non-unions using open reduction and internal fixation, augmented with artificial bone. MATERIALS AND METHODS: A retrospective case series of 16 patients with intra-articular, aseptic non-unions of the distal humerus was analysed for range of motion, pain, Mayo Elbow Performance Scores (MEPS) and Oxford Elbow Scores (OES) after 12 months. Mean age was 44 years (range, 18-84 years) and mean total follow-up was 43 months (range, 24-62 months). RESULTS: All subjective and objective scores were significantly higher 12 months after treatment with internal fixation and artificial bone augmentation; the mean improvement on the MEPS was 18 points and 17 points on the OES. All patients returned to work, most without limitations. Autografts had worse outcomes compared to allografts regarding post-operative pain and time to return to work. No adverse events related to the artificial bone augmentation were seen and all fractures consolidated. CONCLUSION: The use of two locking plates and bone graft augmentation with autografts or allografts with artificial bone grafts is a successful treatment of intra-articular distal humeral non-unions after hardware failure or biological limitations. CLINICAL SIGNIFICANCE: The use of artificial bone in the treatment of septic non-unions of the upper limb is safe. When no autograft is possible because of concurrent morbidity, it can be used alone or combined with an allograft to reconstruct the affected bone without leading to extra morbidity or complications. HOW TO CITE THIS ARTICLE: Rollo G, Vicenti G, Rotini R, et al. Open Reduction and Internal Fixation Using Double Plating with Biological and Artificial Bone Grafting of Aseptic Non-unions of the Distal Humerus: Clinical Results. Strategies Trauma Limb Reconstr 2021;16(3):144-151.

Clinico-Radiological Features of Tumor-like Lesions of the Upper Limbs: don't worry about those lumps.

Tumor-like lesions of the upper limb are more frequent than malignant neoplastic lesions and they represent a wide and heterogeneous group of disorders. The combination of clinical evaluation and imaging is the first pivotal step to attempt a distinction between benign and malignant masses, since there are important implications for further management, such as the requirement for conservative or interventional treatment. The classification of these pseudo tumoral lumps remains arbitrary and is still a matter of debate, currently based on a conjunct clinico-radiologic approach. In this article, we review various types of tumor-like lesions of the upper limb in terms of imaging approach and related clinic features, proponing a descriptive classification, useful in clinical practice to recognize these disorders, and to avoid unnecessary or potentially harmful procedures.

In vitro study of the inhibition and induction of human cytochromes P450 by crystalline glucosamine sulfate.

The induction and inhibition of human hepatic cytochrome P450 (CYP) isoforms by crystalline glucosamine sulfate (CGS) was investigated in vitro. Inhibition of CYP1A2, CYP2E1, CYP2C19, CYP2C9, CYP2D6, and CYP3A4 by CGS was assessed using recombinant human enzymes incubated with CGS (up to 3 mM expressed as free base). Induction of CYP1A2, CYP2B6, CYP2C9, CYP2C19 and CYP3A4 by CGS (0.01, 0.3 and 3 mM) was evaluated in cryopreserved human hepatocytes, by determining CYP mRNA expression using quantitative RT-PCR. CGS produced no inhibition or induction of any the CYP enzymes tested at concentrations hundred folds higher than the steady state peak plasma concentrations (approximately 10 microM) observed in man after therapeutic doses of CGS of 1500 mg once a day. Therefore, no clinically relevant metabolic interactions are expected between CGS and co-administered drugs that are substrates of the CYP enzymes investigated.

Glucosamine binding to proteins in plasma and synovial fluid and blood cell/plasma partitioning in mouse and man in vitro.

Protein binding of [14C]glucosamine (400, 1000 and 4000 ng/ml) was evaluated in human and mouse plasma and in human synovial fluid. Blood cell/plasma partitioning in human and mouse was also determined. There was no measurable protein binding of [14C]glucosamine. Its association with human and mouse blood cells ranged from 43-47% and from 27-29%, respectively. Therefore, the unbound (pharmacologically active) fraction of glucosamine in plasma and at the site of action (the joint) is the same. Protein binding displacement drug-drug interactions are unlikely during the clinical use of crystalline glucosamine sulfate. No corrections are needed, either for unbound fraction when comparing human and mouse pharmacokinetic data or for blood cell/plasma partitioning to assess glucosamine total blood clearance from plasma data in these two species.

Periprosthetic fractures of the humerus.

Classifications have been previously reported and biomechanical studies have been performed, but the management of humeral fractures between implants remains problematic. At the time of arthroplasty, planning of the optimum length of the prostheses is required, especially for patients being considered for a second arthroplasty in the ipsilateral elbow or shoulder. Current treatment may be conservative if reduction can be obtained and the prostheses are stable, or it may be surgical using internal fixation with plates, strut grafts, double plates, or a plate and strut graft construct if the fracture extends around the components of the prosthesis and autogenous bone grafting.