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Biomedical subjects

R Mosheiff

Publications and source records attributed to R Mosheiff.

At least 37 records · Page 2Linked to original sources
PubMed1997

The hybrid ring tubular external fixator: a biomechanical study.

OBJECTIVE: To measure and compare the mechanical properties in bending of the four-ring, and three-ring/one-tube hybrid external fixation frames. DESIGN. IN VITRO: measurements of the mechanical behaviour of ring and ring-tubular external fixation frames. In the latter, one ring of the full circular frame was replaced by one tube and Schanz screws. BACKGROUND: The mechanical properties of the classical Ilizarov four-ring external fixation frames has been compared to those of other external fixation frames by various authors. However, in clinical practice the hybrid fixation frame is being used with increasing frequency. Therefore the mechanical properties of the latter are of immediate interest and clinical value. METHODS: On explanted sheep tibiae with single and double osteotomies, frame stiffness in the four-point bending mode was measured at different K-wire tensions, comparing the values obtained from four-ring frames, to those of three-ring-tubular hybrid frames. These measurements were made under conditions of (a) bone distraction (BD), and (b) segment transport (ST), both at the initial and final stages of this procedure. RESULTS: In circular frames, frame stiffness in bending for increasing K-wire tension showed a Gaussian distribution both in distraction and post-ST with an optimum at 1000 N. In ring tubular hybrid frames, however, frame stiffness showed a more linear relationship to K-wire tension. CONCLUSIONS: In the four-ring Ilizarov external fixation frame, the exchange of one ring with one tube and one Schanz screw both reduced frame stiffness in bending and converted to linear its relationship to K-wire tension. RELEVANCE: Under clinical conditions, the use of a similar ring tubular hybrid external fixator allows the adjustment of frame stiffness in a simple and practical way. This is not the case with the original ring fixation frame.

Journal Article↗
PubMed1997

Eosinophilic granuloma of the spine.

Twenty patients treated for eosinophilic granuloma of the spine were studied. Only 40% demonstrated the classical radiographic picture of vertebra plana. In 60% a lytic lesion of the vertebral body or the posterior elements was found. Seven patients underwent surgery; the indications were neurological involvement or failure of the biopsy to disclose the diagnosis. At an average follow-up period of 7 years, 17 patients are well and alive with no residual spinal pain, neurological compromise, recurrent disease, or extraskeletal involvement. Vertebral body collapse underwent some regeneration but did not regain full body height. In several patients this resulted in a local deformity. In patients with unifocal spinal eosinophilic granuloma, watchful observation with no treatment other than spinal support is warranted. In patients with neural involvement or multifocal lesions, a more active treatment, including surgery, may be indicated.

Adolescent↗
PubMed1997

Nonunion of a fracture of the lateral malleolus: a case report and review of the literature.

Nonunion of a fracture of the lateral malleolus is a rare condition. We present a case of established nonunion of a fracture of the lateral malleolus confirmed and treated surgically, using debridement and internal fixation with autologous bone graft. At 5-year follow-up, the fracture was united but the patient still showed clinical signs of reflex sympathetic dystrophy. Male gender, supination fractures, Weber type C fractures, and primary internal fixation are cited as possible risk factors. Prognosis is variable.

Adult↗
PubMed1997

Cyclosporin A and its non-immunosuppressive derivative exhibit a differential effect on cell-mediated mineralization in culture.

Chronic immunosuppressive treatment with cyclosporin A (CsA) is associated with decreased bone density. However, in culture, CsA inhibits osteoclast differentiation and bone resorption. This raises the question as to whether CsA also affects osteoblast function. Immunophilin, one of the CsA-binding cyclophilins that is implicated in the immunosuppressive action of CsA via calcineurin, is a peptidyl prolyl cis-trans isomerase (PPl). CsA also binds a mitochondrial membrane PPl which is implicated in controlling permeability transition pores. Therefore, in the present study we tested the effect of CsA on cell mediated mineralization in parallel with mitochondrial rhodamine retention as an indicator of mitochondrial membrane potential Rat marrow stromal cells were grown in dexamethasone (DEX) medium to stimulate mineralization in culture, and CsA was added to various cultures using different treatment schedules. Low dose (0.1 microM) CsA inhibited mineralization, compared to controls, when present in the cultures during days 3-11 of DEX stimulation. Contrarily, high dose CsA (1.0 microM) resisted the inhibitory effect of the low dose. SDZ 220-384 (SDZ), a non-immunosuppressive derivative of CsA which is known, like CsA, to bind to mitochondrial cyclophilin but does not inhibit calcineurin, was also tested. Both high and low doses of SDZ decreased mineralization when present in the cultures from day 3 or from day 0. The similar effect of the low CsA dose and SDZ on mineralization is in accord with their ability to block permeability transition pores. The differential effect, on day 21 mineralization, between high CsA dose and SDZ took place in parallel to their opposing effects on mitochondrial membrane potential. On days 4-8, mitochondrial rhodamine retention was higher under CsA than under SDZ. Under these conditions there was no significant difference between the effects of these drugs on cell proliferation measured on day 11; there was a minor decrease in specific alkaline phosphatase activity by SDZ, too small to explain the extent of mineralization inhibition by SDZ. These results suggest that permeability transition pores might be involved in controlling mineralization. Unlike SDZ, CsA exhibits an additional effect on the mitochondrial membrane potential and on mineralization when applied at a high dose on day 3. Therefore identifying the additional activity of high dose CsA, which is missing in SDZ, may be beneficial. Such activity is expected to resist changes in rhodamine retention and decreased mineralization induced by SDZ, and yet enable preservation of immunosuppressive activity of CsA.

Alkaline Phosphatase↗
PubMed1997

[Surgical repair of fractures of the clavicle in the adult].

Clavicular fractures make up 45% of shoulder girdle fractures. The clavicle's susceptibility to injury is due to its subcutaneous position and its role as the bony connection between the thorax and the shoulder. In 95% of cases the mechanism of injury is a direct blow to the shoulder. These fractures are usually treated conservatively without surgery. But there are a few such fractures that require surgical repair in order to unite well. 9 patients were operated on for clavicular fractures during 1991-1995. The indications for surgical repair were lateral-third fracture, floating shoulder, neurovascular deficit or nonunion. The methods used were open reduction and fixation with either plate and screws, Kirchner wires, cerclage or a combination. All fractures united well, with no infections or new neurovascular deficits. Good range of shoulder motion and acceptable cosmetic results were achieved in all. 1 patient had functional limitation due to brachial neuritis caused by brachial damage at the time of injury. Indications for surgical repair and the methods used in these cases are similar to those described in the literature. The high rate of union and absence of complications support surgical repair for the few calvicular fractures that are not likely to unite properly.

Adult↗
PubMed1996

[Immediate posterior stabilization of pelvic fractures using threaded compression rods].

Operative management of pelvic ring disruptions remains a challenge for the orthopedist. Surgical stabilization of an unstable pelvic ring not only involves urgent control of shock, but also protects soft tissues and enables the patient to ambulate earlier and to be comfortable when resting. Appropriate management of pelvic ring injuries requires understanding the anatomy and biomechanics of the pelvis and the mechanism of injury. The choice of posterior stabilization depends on the type of fracture. In this study we evaluated posterior tansiliac fixation using threaded compression rods (sacral bars), 1 of the techniques for treating pelvic instability with disruption of the posterior osseous - ligamentous complex. We used this method during 1987 - 1991 on 17 multitrauma patients with unstable pelvic injuries. We also conducted a long-term follow-up of more than 2 years. The 2 type C3 patients required revision of the posterior fixation, due to loss of stability and recurrence of dislocation of the sacroiliac joint. This seems to support the view that posterior sacral bar fixation is not suitable for bilateral rotational and vertical instability, and that it should be limited to certain posterior injury patterns, including lateral compression injuries and unilateral vertical instability when the contralateral hemipelvis is stable. It is important therefore, that the trauma surgeon be familiar with more than 1 technique of stabilization. Our study indicated that fixation with sacral bars is still an easy, safe and useful method for treating posterior pelvic instability, even though anatomical reduction of the sacroiliac joint is difficult. It should be one of the techniques with which the orthopedic trauma surgeon is acquainted and is ready to use when necessary.

Follow-Up Studies↗
PubMed1995

A double-blinded, randomized, controlled clinical trial to compare cefazolin and cefonicid for antimicrobial prophylaxis in clean orthopedic surgery.

A double-blind, prospective randomized study was performed to compare cefazolin and cefonicid given for prophylaxis to 102 patients undergoing orthopedic surgery. Risk factors (e.g., age, sex, type of operation performed) among the two groups were similar. All patients had foreign material (prosthesis or other hardware) inserted at operation. There was a total of 6 infections (3 wound and 3 urinary tract) in 6 patients among the 48 receiving cefazolin (12.5%), whereas no infections were observed among the 54 patients who received cefonicid. Cefonicid, given once daily, provides protection against postoperative infection that is not inferior to cefazolin. A larger study is needed to confirm whether cefonicid is indeed superior to cefazolin.

Adolescent↗
PubMed1994

Hyperextension fracture-dislocation of the thoracic spine with paraplegia in a patient with diffuse idiopathic skeletal hyperostosis.

The case is described of a hyperextension thoracic spine fracture in a patient with diffuse idiopathic skeletal hyperostosis (DISH). A 70-year-old woman awoke paraplegic after retroperitoneal surgery after having been positioned in the hyperextended axially rotated position. Imaging demonstrated a T9-10 fracture-dislocation with severe pressure on the spinal cord, as well as findings typical of DISH. This case emphasizes the danger inherent in manipulating the ankylosed hyperostotic spine. It is proposed that patients undergoing surgery in this position should be evaluated for DISH as an additional risk factor.

Aged↗
PubMed1994

The role of intramedullary nailing in modern treatment of open fractures of the tibia and femur.

The increasing incidence of open tibial and femoral fractures causes great suffering by patients and is an enormous economic burden, necessitating improved treatment. The current treatment of these fractures is reviewed, as well as the evolving role of intramedullary nailing in this treatment. Intramedullary nailing seems to give better results than external fixation in Gustilo type I and II fractures, and is at least as good in type III. The introduction of the non-reamed interlocking intramedullary nail may bring about even better outcomes. Any improvements in treatment should be based on thorough understanding of the biology and biomechanics of the injury.

Bone Nails↗
PubMed1993

Osteomyelitis of the pelvis.

Four cases of osteomyelitis of the pelvis are reported to demonstrate the several clinical syndromes to which this disease can give rise. Extensive surgical drainage and antibiotic treatment led to recovery in all cases.

Adolescent↗
PubMed1993

Anterior vascularized rib strut graft in the treatment of Pott's disease in the young child.

Two young children suffering from acute thoracic kyphosis due to vertebral tuberculosis (Pott's disease) are described. One patient presented with recent onset spastic paraplegia due to cord compression. Anterior decompression and stabilization with a vascularized rib strut graft was performed in both patients. The neurological recovery in the compromised patient was remarkable; spinal stability was achieved in both patients, thus avoiding the necessity for a posterior spinal fusion.

Child, Preschool↗
PubMed1992

Use of dual-energy X-ray absorptiometry (DEXA) to follow mineral content changes in small ceramic implants in rats.

Dual energy X-ray absorptiometry (DEXA) imaging was used to quantify bone ingrowth into hydroxyapatite (HA) ceramic implants in rats. HA cylinders implanted in the proximal tibiae were followed for 13 wk. The increase in alkaline phosphatase (ALP) activity within the implants preceded the increase in mineral content as measured non-invasively by the DEXA technique. This was consistent with the timing of ALP activity in respect of mineralization as they occur during fracture healing. The results show that DEXA imaging is useful in measuring bone ingrowth into small ceramic HA implants in vivo, despite the high mineral content background of the implant scaffold.

Absorptiometry, Photon↗
PubMed1991

[Interlocked intramedullary nailing of the femoral shaft].

Femoral shaft fracture is usually caused by significant trauma. Conventional treatment is surgical fixation with an intramedullary nail. The addition of interlocking screws has enabled control of rotation at the fracture site as well as the maintenance of correct femoral length. During 1987-1989 we operated on 21 patients with 22 fractures of the femur using the interlocked nail. All fractures had united after an average of 3 months, and the patients returned to normal activity after about a year. There was no mortality nor were there deep wound infections or neurovascular injuries. Complications were infrequent and consisted of pressure signs in the perineum, shortening of the femur and discomfort along the edges of the hardware. Our results support the use of the interlocked nail for femoral fractures when there is no other way to control femoral length or prevent rotation of the fractured elements.

Bone Nails↗