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Biomedical subjects

J B Carr

Publications and source records attributed to J B Carr.

At least 37 records · Page 2Linked to original sources
PubMed1993

Fracture blisters: clinical and pathological aspects.

Fracture blisters are tense vesicles or bullae that arise on markedly swollen skin directly overlying a fracture. There is very little objective data in the literature detailing their characteristics and management. All fracture blisters that occurred over a 3 1/2-year period were studied retrospectively at four hospitals, of which three were level I trauma centers. A total of 53 blisters developed in 51 patients. They occurred in characteristic locations along the human musculoskeleton, most commonly overlying the tibia, ankle, and elbow. They arose within 24-48 h of acute injury in most instances. The timing of surgical intervention affected the occurrence of fracture blisters. Those patients with acute fractures who underwent open reduction internal fixation (ORIF) within 24 h of injury had the lowest incidence of fracture blisters (2.0%) compared with those delayed for > 24 h (8.0%) (p < 0.001). In those patients with fracture blisters present at time of surgery, patient care was affected in 10 of 13 cases (71%). Two of these were major complications occurring as postoperative wound infections. Other management problems consisted of delaying surgery, and changing in the operative plan. There were no adverse affects on patient care when the fracture blister developed postoperatively. Twenty-one fractures with blisters were treated by closed means, with the presence of fractures blisters delaying closed reduction and casting in two. Biopsy examination of 15 blisters supported the clinical impression that fracture blisters are subepidermal vesicles. The blister fluid was found to be a sterile transudate. Microbial evaluation of 11 ruptured fracture blisters demonstrated colonization (primarily with skin pathogens), occurred soon after blister rupture, and continued until reepithelialization.

Adult↗
PubMed1993

A simplified method of total contact casting for diabetic foot ulcers.

A simplified method of total contact casting for diabetic plantar ulcerations is described in which a standard, well-molded short-leg walking cast is applied. Weekly cast changes are performed initially, followed by longer cast change intervals. Either fiberglass or plaster casting tape appears equally efficacious. Healing of all ulcers was demonstrated in 12 patients treated with this technique.

Aged↗
PubMed1993

A comparison of femoral neck fixation with the reconstruction nail versus cancellous screws in anatomic specimens.

Femoral neck fixation techniques were applied to five matched pairs of autopsy specimens to evaluate the fixation of the Russell-Taylor femoral nail in ipsilateral neck and shaft fractures of the femur. Reconstruction nail fixation of the femoral neck was compared with that of three parallel screws. The intact and postfixation femora were subjected to an applied bending moment in 0 degrees, 30 degrees, and 90 degrees of simulated hip flexion. The bending stiffness was determined from the load deformation data for each intact femur and then after the appropriate fixation. The fatigue response of the fixation, presence of osteopenia, degree of fracture reduction, and device alignment showed that the stiffness ratio (fixed to normal) of the nail was greater in most specimens. There was no statistical difference in retained stiffness after cyclic loading between the nail and cancellous screw fixations. The ultimate strength of the nail was 2.5 times the strength of the screw fixation of the femoral neck. Thus, the nail provided biomechanically sound fixation of the femoral neck.

Aged↗
PubMed1993

Mechanism and pathoanatomy of the intraarticular calcaneal fracture.

The mechanism and pathoanatomy of the acute intraarticular calcaneal fracture is produced by axial loading. A combination of shear and compression forces produce two characteristic primary fracture lines. Shearing forces produce a fracture dividing the calcaneus into medial and lateral portions. This fracture line typically splits the posterior facet and can extend anteriorly to involve the anterior and cuboid facets. Compression forces divide the calcaneus into anterior and posterior portions. This fracture line can extend medially to involve the middle facet. Loss of calcaneal height and length are readily explained by this mechanism.

Calcaneus↗
PubMed1991

1991 Volvo Award in experimental studies. Cauda equina syndrome: neurologic recovery following immediate, early, or late decompression.

An animal model of cauda equina syndrome was developed. Neurologic recovery was analyzed following immediate, early, and delayed decompression. Five experimental groups, each containing six dogs, were studied. Compression of the cauda equina was performed in all 30 dogs following an L6-7 laminectomy. The cauda equina was constricted by 75% in each group. The first group was constricted and immediately decompressed. The remaining groups were constricted for 1 hour, 6 hours, 24 hours, and 1 week, respectively, before being decompressed. Somatosensory evoked potentials were performed before and after surgery, before and immediately after decompression, and 6 weeks following decompression. Daily neurologic exams using the Tarlov grading scale were performed. At 6 weeks postdecompression, all dogs were killed, and the neural elements analyzed histologically. Following compression, all 30 dogs had significant lower extremity weakness, tail paralysis, and urinary incontinence. All dogs recovered significant motor function 6 weeks following decompression. The dogs with immediate decompression generally recovered neurologic function within 2-5 days. The dogs receiving 1-hour and 6-hour compression recovered within 5-7 days. The dogs receiving 24-hour compression remained paraparetic 5-7 days, with bladder dysfunction for 7-10 days and tail dysfunction persisting for 4 weeks. The dogs with compression for 1 week were paraparetic (Tarlov Grade 2 or 3) and incontinent during the duration of cauda equina compression. They recovered to walking by 1 week and Tarlov Grade 5 with bladder and tail control at the time of euthanasia. Immediately after compression, all five groups demonstrated at least 50% deterioration of the posterior tibial nerve evoked potential amplitudes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Varus of the talus in the ankle mortise secondary to calcaneus fracture. A case report.

Varus displacement of the talus in the ankle mortise secondary to a calcaneus fracture was observed in a 33-year-old man. Similar to the calcaneus fracture-dislocation, the mechanism involved inferior and medial displacement of the talus into the body of the calcaneus. The patient's ankle deformity was not corrected by a lateral ankle ligament reconstruction. Correction required a distraction subtalar bone block fusion. Successful reconstruction of the hindfoot after calcaneus fractures requires a careful analysis of the pathologic lesion. In this unusual case, correction required restoration of lost hindfoot bone structure.

Adult↗
PubMed1990

Volumetric three-dimensional computed tomography for acute calcaneus fractures: preliminary report.

Volumetric three-dimensional (3-D) computed tomographic reconstructions were performed on three cadaver specimens before and after fracture for 16 acute calcaneal fractures. This "second-generation" 3-D reconstruction technique produced accurate, detailed images of the extra-articular fracture anatomy. Use of this method provided visualization of specific fracture component displacement otherwise unappreciated prior to surgery. In two cases, vertical splits in the superomedial fragment were demonstrated to best advantage by this 3-D technique.

Calcaneus↗
PubMed1990

Closed intramedullary pinning of metacarpal and phalanx fractures.

The surgical technique for closed intramedullary pinning of metacarpal and phalanx fractures is described. Commonly available 0.045 K-wires are used in a manner similar to Ender or Rush nailing of long bone fractures. This technique avoids impaling soft tissue structures--a drawback to more commonly used percutaneous K-wire techniques--and provides sufficient stability to allow early, protected motion.

Bone Nails↗
PubMed1989

Experimental intra-articular calcaneal fractures: anatomic basis for a new classification.

Experimental calcaneus fractures were produce by axially loading 18 specimens. Anatomic dissections were performed and documented. Two constant primary fracture lines were identified, dividing the calcaneus in the coronal and sagittal planes. A constant anterolateral fragment was identified, as were three patterns of calcaneocuboid joint fracture involvement. Based on the pathoanatomy and surgical anatomy of the calcaneus, a medial and lateral column classification is proposed. The medial column includes the superomedial fragment. The lateral column includes the calcaneocuboid joint, lateral wall and posterior facet. This concept can help identify fracture displacements and correlate them with a treatment plan.

Calcaneus↗
PubMed1988

Subtalar distraction bone block fusion for late complications of os calcis fractures.

The authors are presenting a new subtalar fusion technique for late complications of calcaneus fractures. These complications include pain, shoe wear difficulties, and foot deformity. The complex pathology includes incongruous subtalar joint, loss of calcaneal body height, and decreased lateral talocalcaneal angle. The latter two factors can result in tibiotalar neck impingement, a deformity that has received little attention in the literature. The subtalar fusion technique involves distraction of the subtalar joint, insertion of a bone block, and rigid screw fixation. The distraction allows correction of the talocalcaneal relationship and regains lost hindfoot height. The clinical series involved 16 feet with an average follow-up of 19 months. Results were satisfactory in 13 feet. Pre- and postoperative radiographic analysis for tibiotalar impingement, lateral talocalcaneal angle, and talonavicular subluxation was performed, with improvement to a normal range seen in the cases analyzed. The results are encouraging but should be considered preliminary based on the length of follow-up.

Arthrodesis↗
PubMed1987

Occurrence of neonatal and postnatal mortality in range beef cattle. I. Calf loss incidence from birth to weaning, backward and breech presentations and effects of calf loss on subsequent pregnancy rate of dams.

Data from 13,296 calvings collected over a 15-yr period indicated 893 calves died from birth to weaning for an average loss of 6.7%. Calves lost from birth through Day 3 postcalving accounted for a 4.6% loss with an additional 2.1% loss from Day 4 through weaning. Calf deaths from primiparous 2- and 3-yr-old dams accounted for 41.0% of total mortality. Losses within groups were primiparous 2-yr-olds, 10.9%; primiparous 3-yr-olds, 8.7%; second-calf 3-yr-olds, 4.1%; second-calf 4-yr-olds, 8.3%; multiparous 4-yr-olds, 4.8%; and dams 5 yr and older, 5.3%. The majority of calf deaths (57.4%) occurred within the first 24 h postpartum with 75% of the total occurring Days 0 through 7. This loss was similar among all dam age and parity groups. Calf death due to dystocia accounted for the single largest loss category through the first 96 h postpartum, resulting in 69.6, 39.6, 30.8 and 33.3% of the loss incidence for Day 0, 1, 2 and 3 postpartum, respectively. More (P < 0.01) male calves (510, 57.6%) died than females (376, 42.4%). Backward presentations occurred more frequently (P < 0.01) than breech (1.6 vs 0.6% of all births, respectively). Incidence of backward presentation was 2.3%, 5.6% and 0.9% for primiparous 2-yr-old, 3-yr-old and multiparous dams, respectively (P < 0.01); 64.2% of the backward calves were males and 35.8% females (P < 0.01). Survival of calves in backward presentation exceeded (P < 0.01) that of breech calves (70.7 vs 32.9%). Fall pregnancy rate of dams that lost calves and reentered the breeding herd that same year was 72.4% compared to 79.4% (P < 0.01) for contemporary females that did not lose calves. The depression in pregnancy rate was not specifically due to dystocia but apparently to some general effect of calf loss.

Journal Article↗
PubMed1979

Multiple linear and nonlinear regression analyses of factors causing calving difficulty.

Calving difficulty (CD) was analyzed as the dependent variable from observations on 592 first-calf, 2-year-old heifers that were either Angus X Hereford (AH), Charolais X AH or Simmental X AH. Independent variables were birth weight (BW), pelvic area (PA), BW.(33), PA.(5), cow weight (CW), cow condition score (CS) and sex of calf (S). CD was analyzed as score (1 = no difficulty through 4 = extreme difficulty) CD-I, % CD (1 vs 2 + 3 + 4 , CD-II) or % high CD (1 + 2 vs 3 + 4 , CD-III). R(2) values from CD-II and CD-III multiple correlation (R) analyses were consistently lower (.10 to .13) than from the CD-I analysis. When only BW and PA were included in the model, R(2) values for CD-I were .36, .39 and .39 for the linear, quadratic and cubic analyses, respectively. When BW, PA, CW, CS and S were included in the model, the R(2) values for CD-I were .40 and .42 for the linear and quadratic analyses (cubic effects were not tested). In the linear analysis with BW.(33) and PA.(5), the R(2) for CD-I was .36. In all analyses, the order of importance of the factors studied was BW and PA, with a much lower contribution from CW and S. CS did not account for a significant increase in R(2) in any analysis. CD remained below 50% whenever the PA BW ratio exceeded 8.4. This ratio is a convenient practical method to relate PA and BW to CD. Conclusions are that the linear effects of BW and PA account for the majority of the identified variation in CD (R(2)) and that small increases in R(2) can be obtained by adding CW, CS and S to the model and/or by expanding the model to include quadratic effects.

Journal Article↗