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Biomedical subjects

R W Bucholz

Publications and source records attributed to R W Bucholz.

At least 19 recordsLinked to original sources
PubMed1999

Three-dimensional collagen gel culture promotes osteoblastic phenotype in bone marrow derived cells.

When calvarial cells or osteogenic cell lines were cultured in type I collagen gel, calcification was observed early and diffusely compared to monolayer culture. Bone marrow derived cells were cultured in three-dimensional type I collagen gel to investigate whether the cells can differentiate into osteogenic cells. In terms of efficient induction of osteogenic differentiation, we compared collagen gel culture to type I collagen coated dish culture and collagen-free plastic dish culture by morphology, alkaline phosphatase activity, and mRNA expression for type I collagen and osteopontin. Bone marrow derived primary cells formed colonies consisting of fibroblastic cells positively expressing alkaline phosphatase activity. Mineral deposition was observed in both primary and the 3rd passaged cells cultured in collagen gel, whereas the 3rd passaged cells on plastic dishes failed to be mineralized. Cells in collagen gel showed higher alkaline phosphatase activity than those in the other two methods suggesting that three-dimensional collagen network stimulated osteoblastic differentiation effectively. The expression level for type I collagen mRNA of the cells in collagen gel was three times higher in the 3rd passaged cells, and was slightly decreased in primary cells compared to the other two methods. The osteopontin mRNA expression of the cells in collagen gel was four times higher in the 3rd passaged cell culture but lower in primary cell cultures. These results suggested that collagen gel culture might be a useful environment for osteogenic induction of passaged cells derived from bone marrow.

Alkaline Phosphatase↗
PubMed1998

Effect of recombinant human bone morphogenetic protein-2 on fracture healing in a goat tibial fracture model.

Bone morphogenetic proteins (BMPs) are considered to have important regulatory roles in skeletal embryogenesis and bone healing. Recombinant human BMPs (rhBMPs) have been shown to heal critical size defects and promote spinal fusion. We studied the effects of rhBMP-2 in an absorbable collagen sponge (ACS) on bone healing in a large animal tibial fracture model. Bilateral closed tibial fractures were created in 16 skeletally mature goats and reduced and stabilized using external fixation. In each animal, one tibia received the study device (0.86 mg of rhBMP-2/ACS or buffer/ACS), and the contralateral fracture served as control. The device was implanted as a folded onlay or wrapped circumferentially around the fracture. Six weeks following fracture, the animals were sacrificed and the tibiae harvested for torsional testing and histomorphologic evaluation. Radiographs indicated increased callus at 3 weeks in the rhBMP-2/ACS treated tibiae. At 6 weeks, the rhBMP-2/ACS wrapped fractures had superior radiographic healing scores compared with buffer groups and controls. The rhBMP-2/ACS produced a significant increase in torsional toughness (p = 0.02), and trends of increased torsional strength and stiffness (p = 0.09) compared with fracture controls. The device placed in a wrapped fashion around the fracture produced significantly tougher callus (p = 0.02) compared with the onlay application. Total callus new bone volume was significantly increased (p = 0.02) in the rhBMP-2/ACS fractures compared with buffer groups and controls regardless of the method of device application. The rhBMP-2/ACS did not alter the timing of onset of periosteal/endosteal callus formation compared with controls. Neither the mineral apposition rates nor bone formation rates were affected by rhBMP-2/ACS treatment. The increased callus volume associated with rhBMP-2 treatment produced only moderate increases in strength and stiffness.

Animals↗
PubMed1997

Polyglycolide bioabsorbable screws in the treatment of ankle fractures.

Twenty-one patients with unstable medial malleolar, bimalleolar, or trimalleolar ankle fractures underwent open reduction and internal fixation of the medial malleolus with 4.5-mm polyglycolide screws. All lateral malleolar fractures were internally fixed with standard metallic implants. Radiographic and clinical follow-up results were available on 16 of 21 patients. All fractures healed at an average of 3.4 months (range, 3-6 months), and there were no medial wound infections. Eight of 16 patients developed an inflammatory reaction to the biodegradable polyester at 3 to 4 months after implantation, including one who developed a sterile draining sinus tract. No surgical or nonsurgical treatment was required in those eight patients. We conclude that whereas polyester screws yield union rates and functional results similar to those of metallic screws in the treatment of medical malleolar fractures, the use of polyglycolide screws is associated with an unacceptable rate of inflammatory reactions.

Adult↗
PubMed1996

Orthopedic surgery.

Explore the source record for details and available documents.

Bone Morphogenetic Proteins↗
PubMed1994

Fixation with bioabsorbable screws for the treatment of fractures of the ankle.

One hundred and fifty-five patients who had a closed, displaced medial malleolar, bimalleolar, or trimalleolar fracture of the ankle were managed with medial malleolar fixation with use of either 4.0-millimeter orientruded polylactide screws (eighty-three patients, study group) or 4.0-millimeter stainless-steel screws (seventy-two patients, control group). All lateral malleolar fractures were stabilized with standard metallic implants. At an average of thirty-seven months (range, twenty-one to fifty-nine months), the radiographic and functional results in the two groups were equivalent. Differences between the two groups with regard to the rates of operative and postoperative complications were not statistically significant. Late spontaneous drainage of the hydrolyzed polylactide was not noted in any patient in the study group. The prevalence of late tenderness over the medial malleolar implant was lower in the patients in whom the fracture had been stabilized with polylactide screws. We conclude that polylactide screws are a safe and effective alternative to stainless-steel screws for the fixation of displaced medial malleolar fractures.

Adult↗
PubMed1992

Exstrophy of the bladder: primary closure after iliac osteotomies without external or internal fixation.

A total of 6 consecutive infants with exstrophy of the bladder underwent iliac osteotomy in association with primary closure of the bladder without internal or external fixation of the bony pelvis. Hospitalization time was short and there were no resulting problems with healing, bony deformities or subsequent ambulation. Fixation of the bony pelvis after iliac osteotomy does not appear to be necessary in nonambulatory patients undergoing primary closure for bladder exstrophy.

Bladder Exstrophy↗
PubMed1989

Interporous hydroxyapatite as a bone graft substitute in tibial plateau fractures.

The metaphyseal defects in 40 patients with displaced tibial plateau fractures necessitating surgical repair were filled with either cancellous autograft or interporous hydroxyapatite. Roentgenographic and clinical assessments at follow-up periods averaging 15.4 months (autograft) and 34.5 months (hydroxyapatite) demonstrated no significant differences in the two groups. Interporous hydroxyapatite is a safe, effective alternative to autogenous cancellous bone for the filling of metaphyseal defects associated with tibial plateau fractures.

Adolescent↗
PubMed1988

Posterior plating of the cervical spine. A biomechanical comparison of different posterior fusion techniques.

Posterior arthrodesis is a preferred treatment for posttraumatic instability of the cervical spine. While most surgical constructs yield predictably high rates of fusion in satisfactory alignment, certain injury patterns involving fractures of the lamina or spinous processes may preclude rigid immobilization by simple wiring techniques. Plate fixation of the posterolateral masses has been advocated for such injuries. The purpose of this biomechanical study was to test the relative stiffness provided by different posterior fusion constructs, including lateral mass plating. All testing was performed on fresh, unembalmed cadaveric spines divided into two vertebral segment units. Muscular tissue was stripped from the specimens, but all discal and ligamentous structures were preserved. Four different posterior fixation constructs were tested. These included 1) Rogers interspinous wiring, 2) Halifax laminar clamps, 3) bilateral 1/3 tubular plates on the lateral masses, using unicortical screws, and 4) bilateral 1/3 tubular plates on the lateral masses, using bicortical screws. Stiffness measurements were taken in both flexion and extension on all specimens. Yield strength and fatigue strength of the spines were not measured. It was found that 1/3 tubular plates secured with bicortical screws to the lateral masses provided the highest mean stiffness. Less stiffness was found in spines stabilized by Halifax clamps, interspinous wiring, and plates secured with unicortical screws. There was, however, no statistically significant difference in stiffness provided by any of these four implants. It was concluded that there is no advantage in plate fixation over standard fusion constructs in augmenting the stiffness of posterior fixation of the cervical spine.

Biomechanical Phenomena↗
PubMed1988

Osteomyelitis of the odontoid process.

Pyogenic osteomyelitis of the odontoid process is a rare condition requiring a high index of suspicion for diagnosis. The three cases presented illustrate that patients with severe neck pain, aggravated by rotation, and persistent fever without apparent source should be studied carefully to exclude infection of the C1-C2 area. The unusual anatomy of the C1-C2 articulation may make routine diagnostic studies difficult to interpret. Computed tomography, magnetic resonance imaging, and 111In-labeled white blood cell scans may improve diagnostic accuracy. Treatment includes rigid immobilization, high dose antibiotics, and surgical stabilization in selected cases.

Anti-Bacterial Agents↗
PubMed1987

Porous hydroxyapatite as a bone graft substitute in diaphyseal defects: a histometric study.

Porous hydroxyapatite (IP200), formed by conversion of the Poritidae porites exoskeleton, has pores averaging 230 microns and pore interconnections averaging 190 microns in diameter. In the distal radial diaphyses of 14 dogs, bilateral 7.5 X 20 mm cortical windows were created and fitted with 5 X 7.5 X 20 mm blocks of IP200 implants and iliac autografts. Both implanted and contralateral grafted radius specimens were retrieved at 3, 6, 12, 24, and 48 months. Unstained undecalcified sections were examined by microradiography and UV epi-illumination. Stained undecalcified sections were examined by light microscopy and quantitated by histometric methods. Implant specimens demonstrated good union and bone ingrowth at all time intervals. The implant specimens were composed of (mean +/- SE) 10.6% +/- 1.0% soft tissue, 51.2% +/- 1.3% bone, and 38.2% +/- 1.0% IP200. The graft specimens showed good union with little apparent ingrowth at 3 months, followed by progressive appositional closure of cancellous spaces. The graft specimens contained 21.9% +/- 0.9% bone at 3 months with increases at each time interval to 73.1% +/- 8.7% at 48 months. The volume fraction and mean width of IP200 did not change with time, confirming the absence of implant biodegradation. The volume fraction and mean width of bone remained stable in the implant but increased in the graft specimens, corresponding to graft neocortex formation. It is concluded that implants initially filled in with bone while grafts initially replaced much of their spongiosa and subsequently filled in with bone. Histometry of untreated defects and measurement of mechanical properties are suggested for further study.

Animals↗
PubMed1987

Coralline hydroxyapatite bone-graft substitutes in a canine diaphyseal defect model. Radiographic-histometric correlation.

Radiographic and histometric evaluation of a new form of bonegraft substitute derived from reef-building sea coral was performed in a canine diaphyseal defect model. Comparably sized blocks of this material and iliac crest autograft were placed into bilateral surgically created cortical windows in the distal radial diaphyses of 14 dogs. Representative graft specimens of both types underwent densitometric radiography and harvesting at 3, 6, 12, 24, and 48 months. Histometric analysis of implant specimens revealed satisfactory union and native osseous ingrowth at all time intervals. Graft specimens exhibited adequate union with scant host bone ingrowth at three months, but subsequent progressive appositional closure of cancellous spaces during the ensuing 45 months. Volume fraction and mean width of host bone remained stable in the implants but increased in the grafts due to neocortex formation. Stereologic distribution of bone was homogeneous in both implant and graft specimens, and no evidence for biodegradation of the former was observed. Corrected transmission density determinations accurately reflected these differences but correlated significantly with volume fractions and tissue widths of bone and soft tissue only in the autografts. These results support the successful early application of coralline hydroxyapatite bone graft substitutes as an alternative to autogenous grafting in the clinical setting and emphasize the potential role of noninvasive densitometric techniques in monitoring the incorporation of bone-graft materials.

Absorptiometry, Photon↗
PubMed1987

Fatigue fracture of the interlocking nail in the treatment of fractures of the distal part of the femoral shaft.

The clinical and mechanical factors predisposing to a fatigue fracture of an interlocking nail were studied in seven patients who were treated for a fracture of the distal part of the femur. In all patients, the fracture of the femur was five centimeters or less from the more proximal of the two distal screw-holes. Finite-element analysis revealed that the stress on the nail exceeded its fatigue endurance limit and that the femur had to regain 50 per cent of its original stiffness through healing to accommodate weight-bearing without the risk of fatigue failure of the nail. The risk of fatigue failure may be minimized by using nails that have a larger diameter and by avoiding early weight-bearing.

Adolescent↗
PubMed1987

Hydroxyapatite and tricalcium phosphate bone graft substitutes.

Autografts have consistently outperformed calcium phosphate implants in most experimental models and clinical applications. However, human trials in metaphyseal defects demonstrate comparable results with autograft, hydroxyapatite, and TCP. Diaphyseal fractures and segmental defects represent more challenging problems, with less predictable results achieved with the synthetic bone graft substitutes. Improvements in the pore configuration, mechanical properties, and osteoinductive capacity of these implants should widen their future clinical application.

Adolescent↗
PubMed1986

Coralline hydroxyapatite bone graft substitutes in a canine diaphyseal defect model: radiographic features of failed and successful union.

Radiographic and densitometric evaluation of a new type of bone graft substitute derived from reef-building sea coral via a hydrothermal chemical exchange process was undertaken in a canine diaphyseal defect model. Comparably sized blocks of this material and autogenous iliac cortical-cancellous graft were implanted into the respective radial diaphyses of seven dogs. Qualitative and quantitative radiographic assessment was performed during the immediate postoperative period and at 3 months following surgery. Significant complications were observed radiographically in over half of the coralline implanted limbs, including failed union, graft fracture, and loosening of internal fixation hardware. No significant difference was noted in degree of native osseous in-growth between the implants and the autografts, and the latter exhibited a higher success rate. Radiographic film densitometry was found not to be reliably predictive of coralline implant behavior in the individual case. It is concluded that coralline hydroxyapatite bone graft substitutes appear to offer no particular advantage over autogenous grafts in the management of diaphyseal defects, although further investigation is warranted since other factors may be responsible for the unfavorable findings in this study.

Absorptiometry, Photon↗
PubMed1986

Coralline hydroxyapatite bone-graft substitutes in a canine metaphyseal defect model. Radiographic-histometric correlation.

Radiographic and histometric evaluation of a new form of bone-graft substitute derived from reef-building sea coral was performed in a canine metaphyseal defect model. Blocks of this material were implanted into the proximal tibial metaphyses of eight dogs, with radiographic densitometry and harvesting performed at two, four, six, and 12 months. Histometric analysis demonstrated progressive apposition of host compact bone at the margins and trabecular bone at the interior of the implants with time following surgery. Corrected transmission density determinations correlated significantly with degree of osseous ingrowth (R = -0.78), void volume fraction (R = 0.88), and postoperative interval (R = 0.88). These results support the successful early application of coralline hydroxyapatite bone-graft substitutes as an alternative to autogenous grafting in the clinical setting, and indicate that the course of incorporation into host bone can be noninvasively monitored using densitometric techniques.

Absorptiometry, Photon↗