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Biomedical subjects

B R Moed

Publications and source records attributed to B R Moed.

52 records · Page 3Linked to original sources
PubMed1993

Measurement of intracompartmental pressure: a comparison of the slit catheter, side-ported needle, and simple needle.

An experimental model of acute compartment syndrome involving the anterolateral compartment of the hindlimb in dogs was used to compare three methods of measurement of intracompartmental pressure: the simple-needle technique, use of the slit catheter, and use of the side-ported needle. No statistical difference was found between the values obtained with the slit catheter and those obtained with the side-ported needle; the mean difference was 1.4 millimeters of mercury throughout the range of compartment pressures that were measured. The side-ported needle appeared to be as accurate as the slit catheter for the measurement of compartment pressures (p = 0.355, 1-beta = 0.9). The values obtained with use of the simple needle were consistently higher than those obtained with the other two methods (p < 0.001): an average of 18.3 millimeters of mercury higher than the values measured with the slit catheter and 19.3 millimeters of mercury higher than those measured with the side-ported needle. Clinically, the side-ported needle or the slit catheter can be used to obtain accurate measurements of compartment pressure. Use of the simple 18-gauge needle is not recommended for this purpose.

Acute Disease↗
PubMed1992

Intraoperative somatosensory evoked potential monitoring of the sciatic nerve: an animal model.

Sciatic, peroneal, and tibial nerves were isolated in 18 hind limbs in 10 adult mongrel cats. A pair of needle electrodes was used to stimulate both divisions of the sciatic nerve individually at the level of the popliteal fossa. The sciatic nerve was injured by complete or partial transection, crush, and controlled compression. Motor function was correlated with intraoperative cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings. We observed that significant changes in the waveforms of cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings immediately precede postoperative peripheral nerve deficits, and that loss of motor function may be avoided by immediate response to significant spinal somatosensory evoked potential and cortical somatosensory evoked potential waveform changes. A complete motor palsy can be created in one division of the sciatic nerve while normal tracings are being obtained in the other division of the nerve. Stimulating both divisions may result in a spinal somatosensory-evoked potential/cortical somatosensory evoked potential tracing that masks the deficit that is present in only one nerve division.

Animals↗
PubMed1991

Compartment syndrome after closed intramedullary nailing of the tibia: a canine model and report of two cases.

Two patients developed an anterior tibial compartment syndrome after closed reamed intramedullary nailing of their fractured tibial shaft. Subsequently, a study was undertaken using a canine model to evaluate the risk of compartment syndrome after this operative procedure. A closed tibial fracture was created in 20 mongrel canines by applying a torsional load localized to the tibial shaft through a stress riser made with an intramedullary drill. Compartment pressures were measured in the canine anterolateral and deep posterior leg compartments. In 10 dogs, closed intramedullary nailing with reaming was performed while compartment pressures were measured. The remaining 10 dogs served as controls. Compartment pressures were monitored for 4 hours. In the experimental group, one dog attained and maintained a pressure greater than 50 mm Hg; a second dog maintained a pressure of 20 mm Hg during the postoperative monitoring period. In both of these cases, fasciotomy reduced the pressures to zero. The high tissue pressure readings were localized to the anterolateral muscle compartment. In the control group, no pressures higher than 8 mm Hg were recorded. Compartment syndrome is a potential complication of closed intramedullary nailing of the tibia, and the anterior muscle compartment appears to be the one most at risk. Therefore, perioperative tissue pressure monitoring is recommended.

Adult↗
PubMed1991

Compartment syndrome after low-velocity gunshot wounds to the forearm.

Between 1980 and 1988, 127 patients with 131 low-velocity gunshot wounds to the forearm were treated. In 71 extremities there was no bony injury; 60 extremities sustained fractures. The diagnosis of a compartment syndrome was based on tissue pressure measurements and/or clinical examination. A univariate analysis followed by a multivariate stepwise logistic regression was used to evaluate potential risk factors including fracture location, displacement, comminution, and the quantity of radiographically determined metallic foreign bodies in the wound. A compartment syndrome was diagnosed in 13 of the extremities (10%). Fracture location was the only significant risk factor for the development of a compartment syndrome. Low-velocity gunshot injuries to the forearm are at definite risk for the occurrence of a compartment syndrome. A high index of suspicion is necessary to prevent untoward sequelae. Patients with this injury, especially those with a proximal one-third fracture who constitute an extremely high-risk group, should be monitored closely.

Adolescent↗
PubMed1991

The effect of autogenous bone graft application on wound contamination.

A rat model was created in which contaminated wounds were closed in either the presence or absence of autogenous bone graft. The recipients of bone graft were divided into two groups--one receiving autogenous cancellous bone, the other receiving nonviable autogenous autoclaved cortical bone. Quantitative bacterial cultures were collected both at the time of wound closure and 2 weeks after closure. A significantly increased level of soft-tissue contamination was associated with wound closure in the presence of either type of bone graft, indicating an overall adverse effect on soft tissues. A critical level existed such that at initial bacterial contamination levels greater than 10(4) organisms/g tissue, final contamination levels were significantly elevated. With initial contamination levels less than 10(4) organisms/g tissue, however, final bacterial contamination levels were not significantly different. These results may help explain the different rates of infection that have been reported when delayed primary closure of open fractures is done in conjunction with autogenous bone graft.

Animals↗
PubMed1990

Effects of dynamization after interlocking tibial nailing: an experimental study in dogs.

Dynamization of statically locked tibial nails was studied in a canine model. Reamed static interlocking nails were inserted in 16 canine tibiae with unstable osteotomies. At 8 weeks, half were dynamized. At 20 weeks, the tibiae were harvested and studied radiographically, biomechanically, and histologically. Apparent clinical union was present in all tibiae. Complete radiographic bony union was achieved in 13 of 16, with residual radiolucent lines in two tibiae in the static and one in the dynamic group. Biomechanically, dynamization improved stiffness at the fracture site. Histological patterns were similar, but there were trends toward a denser trabecular callus pattern in the dynamized group. The results of this animal study indicate that although dynamization may have a beneficial effect on the quality of early bony healing, static interlocking does not decrease the rate of bony union.

Animals↗
PubMed1989

Cancellous bone donor site regeneration.

Patients requiring cancellous bone grafting of an extensive deficit or multiple grafting procedures often lack a sufficient quantity of autogenous cancellous donor bone. This study was designed to determine the potential for reharvesting autogenous cancellous bone donor sites in a canine model. Fixed-sized cancellous bone grafts were harvested from the ilium of 12 mature, conditioned dogs. Ilia containing the donor sites were removed from groups of 3 dogs at intervals of 6 weeks, 3 months, 6 months, and 1 year. The donor sites were evaluated by roentgenograms, histology, and histomorphometric analysis and were compared to the opposite, nonoperated ilia, which served as controls. The analysis revealed a gradual replacement of the surgical defect with new cancellous bone by 1 year. Donor site reharvesting is a potential alternative to multiple site grafting or the use of allograft material.

Animals↗
PubMed1986

Immediate internal fixation of open fractures of the diaphysis of the forearm.

Between 1975 and 1983, fifty-seven patients were treated at Sunnybrook and Harborview Medical Centers with immediate internal plate fixation of an open diaphyseal fracture of the forearm. Fifty patients were available for follow-up, which ranged from one to nine years and averaged three years. The injuries were classified on the basis of the extent of soft-tissue injury as defined by Gustilo and Anderson, and consisted of twenty Type-I injuries, nineteen Type-II injuries, and eleven Type-III injuries. The complications included deep infection in two patients and non-union in six. The functional results were excellent or good in 85 per cent of the series. This study demonstrates that immediate stable plate fixation is a beneficial method of treatment of open fractures of the forearm. The results are related to the severity of the initial soft-tissue injury and the surgical technique. Autogenous cancellous bone-grafting at the time of closure of the wound in comminuted fractures in which interfragmental compression cannot be obtained is recommended.

Adolescent↗
PubMed1984

Displaced midline longitudinal fracture of the sacrum.

An unstable displaced midline longitudinal (vertical) fracture of the sacrum, apparently not previously reported, is described. Pitfalls in treatment are elucidated. It is recommended that Pennal 's classification be used to categorize all pelvic fractures in order to ensure early and adequate treatment and minimize the occurrence of disabling sequelae. In the patient reported, complications were bladder prolapse, pelvic instability, and sciatic nerve injury.

Adult↗
PubMedDate not supplied

Ultrasound for the early diagnosis of tibial fracture healing after static interlocked nailing without reaming: histologic correlation using a canine model.

OBJECTIVE: Ultrasound is thought to be clinically useful in evaluating bone formation through its presumed identification of fracture callus. However, documentation of the actual histology of the tissue identified by ultrasound has been lacking. The purpose of this study was to determine the histologic composition of the hyperechoic tissue "seen" by ultrasound. STUDY DESIGN: Unilateral fractures were created in eight canine tibias and then fixed by using locked intramedullary nailing without reaming. The limbs were studied at two, three, four, six, and eight weeks postoperatively with plain radiographs, ultrasound, and ultrasound-directed needle biopsy. RESULTS: The presence of a hyperechoic ultrasound signal was found to have a 100 percent correlation with the presence of hard fracture callus biopsy tissue. In addition, fracture union by ultrasound criteria significantly predated radiographic fracture union (5.6 vs. 7.3 weeks, p = 0.05). CONCLUSIONS: These results support and provide a scientific basis for the clinical use of ultrasound to assess tibial fracture healing following static interlocked nailing without reaming.

Animals↗
PubMedDate not supplied

Ultrasound for the early diagnosis of tibial fracture healing after static interlocked nailing without reaming: clinical results.

OBJECTIVE: Based on the results of a pilot study indicating the potential value of ultrasound (US) as a diagnostic tool for the early assessment of fracture healing and the related need for secondary operative procedures in patients treated by statically locked intramedullary (IM) nailing without reaming, a protocol was established for a larger scale prospective trial. The purpose of this study was to evaluate the outcome of this follow-up trial. DESIGN/METHODS: All skeletally mature patients admitted to the Henry Ford Hospital (Detroit, Michigan) from January 1993 to August 1994 who had sustained an acute fracture of the tibial shaft and who were treated by statically locked IM nailing, without reaming, were candidates for study. Forty-seven patients with fifty fractures that could be evaluated by US were included. The adopted determinants for fracture healing were complete disappearance of the IM nail on US examination performed at six weeks postoperatively, or progressive disappearance of the nail noted between the initial six-week study and a second nine-week US examination, both in conjunction with periosteal callus formation. Radiographs were obtained to monitor maintenance of reduction and to further evaluate fracture healing. RESULTS: Of thirty-eight fractures with a positive US (thirty-two at six weeks, six at nine weeks), thirty-seven healed uneventfully, a positive predictive value of 97 percent. Radiographic fracture healing was not evident until, on average, nineteen weeks after injury. The single false-positive fracture progressed to nonunion. Of the twelve fractures with negative US studies, ten underwent secondary procedures (nine dynamization, one bone graft), with four progressing to nonunion. Two patients refused secondary surgery; screw failure occurred in both. Otherwise, there were no hardware failures in this series. CONCLUSIONS: The results of this study indicate that US may provide important prognostic information concerning fracture healing after unreamed tibial nailing, upon which subsequent treatment can be based.

Adolescent↗
PubMedDate not supplied

Unreamed retrograde intramedullary nailing of fractures of the femoral shaft.

OBJECTIVE: To evaluate the efficacy of unreamed retrograde intramedullary (IM) nailing of fractures of the femoral shaft in a second series of patients using modifications suggested from our initial study. DESIGN: Prospective. SETTING: Level I trauma center. METHODS: Based on the findings of a previous study, we began a clinical series incorporating changes consisting of (a) inclusion of any patient with a femoral shaft fracture amenable to IM nailing (i.e., closed physes), (b) primary use of a split patellar tendon intercondylar distal femoral entry portal, and (c) the use of a full-length femoral implant having variable size availability and dynamization capability. Over a twelve-month period, thirty-four patients with thirty-five femoral shaft fractures were treated. The protocol called for planned dynamization in statically locked stable fractures and unstable fractures showing minimal healing at six to twelve weeks. Functional outcome was assessed by using the Knee Society clinical rating system. RESULTS: Incorporating the concepts of canal fill and early dynamization, there were only two nonunions (6 percent) in this series as compared with 14 percent in the previously reported series with an overall shorter time to union (12.6 versus 15 weeks). There were no infections or malunions. Postoperative complaints of knee pain were minimal (knee score average: 98 points) and knee function was excellent (knee score average: 97 points). CONCLUSIONS: Although not advocated as a replacement for other techniques, unreamed retrograde nailing is presented as a safe and beneficial fracture fixation method that should be added to the orthopaedic surgeon's treatment armamentarium. The operative technique is quick and simple, and blood loss is minimal. Early nail dynamization and early weight-bearing are important in minimizing the risk of nonunion.

Adolescent↗
PubMedDate not supplied

Retrograde nailing of the femoral shaft.

Retrograde intramedullary nailing of fractures of the femoral shaft with use of a distal intercondylar intra-articular entry portal is a relatively new surgical technique. This method of nailing represents a modification of the previously described procedure in which an extra-articular entry portal in the medial femoral condyle was used. The earlier procedure was plagued by technical difficulties, which limited its use; these problems were mainly related to the fact that the entry portal was not in line with the intramedullary canal, as well as to the fact that purpose-specific implants and instrumentation were not available. Modification of this technique, by using the intercondylar entry portal and a nail designed for retrograde insertion, has proved very effective in clinical studies. There have been theoretical concerns regarding postoperative knee function and intraoperative injury to important anatomic structures, such as branches of the femoral nerve; however, laboratory and clinical findings have dispelled many of these concerns and have provided firm support for continued use of the technique. Nonetheless, further study is required to delineate the long-term outcome of knee joint function. Current indications for use of this technique include multisystem injuries, multiple fractures (including ipsilateral lower-limb combination injuries), ipsilateral vascular injuries, periprosthetic fractures, and morbid obesity.

Equipment Design↗
PubMedDate not supplied

Screw fixation of closed oblique and spiral fractures of the tibial shaft.

The difficulty of reducing and holding fractures of the tibial shaft, especially those of oblique configuration, is well known. A high incidence of malalignment after closed treatment of fractures of the distal third of the tibial shaft, as compared with fractures in more proximal sites, has also been reported. In 29 of 37 fractures in the present study treatment by closed methods had failed. In highly selected cases of closed tibial shaft fractures, notably those in the distal third and at the middle third-distal third junction with an oblique or a spiral configuration and an unacceptable position after closed reduction, simple screw fixation followed by plaster immobilization provides an effective treatment alternative.

Adolescent↗