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.

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.

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.

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.

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.

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.

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.

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.

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.

Physeal injuries of the cervical spine

Four cases of cervical spine growth plate ("ring apophysis") injury are described. Two nonfatal injuries involved anterior displacement of a portion of the inferior physis and epiphyseal ossification center in the lower cervical spine. Neither injury was associated with neurological damage. Follow-up roentgenograms demonstrated healing, but with a spur-like prominence in one patient. A third patient sustained a fatal separation through the inferior end plate of C2. The fourth patient sustained a complete separation of C6 from C7. These injuries are correlated with pathologic specimens and normal developmental anatomy.

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.

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.

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.

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.

Tension band wiring of displaced tibial tuberosity fractures in adolescents

Twelve adolescent boys with avulsion fractures of the tibial tuberosity were treated with open reduction and tension band wire fixation. Fasciotomies were required in two cases for associated compartmental syndromes. All fractures healed in anatomic position. The tension band wire assisted both in neutralizing tensile (distracting) forces and compressing comminuted fragments. Early functional motion was started within four weeks. Osgood-Schlatter disease was diagnosed in five of the 12 patients. The apparent high incidence of this fracture pattern in the community prompted the recommendation to restrict jumping sports for adolescent boys with active Osgood-Schlatter disease.

Porous hydroxyapatite as a bone-graft substitute in metaphyseal defects. A histometric study

Porous hydroxyapatite (Interpore 500) formed by conversion of the Porites goniopora coral exoskeleton has pores averaging 600 micrometers and pore interconnections averaging 260 micrometers in diameter. In the proximal tibial metaphysis of eight dogs, a defect one cubic centimeter in size was created unilaterally and was fitted with a block of Interpore 500. Both proximal tibial metaphyses were retrieved at two, four, six, and twelve months. Stained undecalcified sections were examined by light microscopy and quantitated by histometric methods. The implant-side specimens contained compact bone along the external surface and trabecular bone interiorly. The interior of these specimens was composed of 51.9 +/- 1.3 per cent soft tissue, 13.0 +/- 1.2 per cent bone, and 35.1 +/- 1.2 per cent Interpore 500 (mean and standard error). The interior of the normal specimens was composed of 79.7 +/- 1.4 per cent soft tissue and 20.2 +/- 1.4 per cent bone. The allocation of implant pore space between bone and soft tissue was proportional to that of bone and soft tissue in the normal tibiae. The stereological distribution of regenerated bone in the porous hydroxyapatite was also the same as in the normal tibiae. The appositional process of incorporation of the implant was confirmed by the finding that 66.5 per cent of the surface of the Interpore 500 was covered with bone ingrowth at twelve months.

Classification of injuries to the thoracolumbar spine

Significant advances have been made over the past 40 years in the understanding of the pathoanatomy, biomechanics, and neurophysiology of thoracolumbar injuries. These improvements are reflected in the sophisticated classifications currently in use. Yet, we remain in a transitional phase of our classification of these fractures. Future schemes will probably offer two precise classifications--one neurologic and one structural--for every injury.

Injuries of the pelvis and hip

Pelvic, acetabular, and hip fractures have a very high incidence of catastrophic early and late complications. In the emergency department, attention should be focused on the prompt and judicious management of concurrent local visceral and systemic problems. The eventual outcome of any pelvic or hip injury reflects the adequacy of the emergency treatment.

The role of computerized tomographic scanning in the evaluation of major pelvic fractures

Twenty-five patients with double vertical fractures of the pelvic ring had evaluations by both plain radiography and computed-tomography scanning of the pelvis. In eight of the twenty-five patients, the interpretation that was made from the plain radiographs, based on the classification of Pennal et al., changed when additional anatomical information was provided by the computed-tomography scan. We recommend that computed tomography be used for: (1) double vertical fracture-dislocations of the pelvic ring in which plain radiographs are inadequate to judge pelvic stability, (2) fractures of the pelvic ring with extension into the acetabulum, and (3) major injuries to the hemipelvis that are to be treated by open reduction and internal fixation. However, due to the increased cost and radiation exposure, routine computed-tomography scanning is not justified for all injuries to the pelvic ring.

Development of a variable stiffness external fixation system for stabilization of segmental defects of the tibia

The mechanical properties of a variable stiffness external fixation system were explored. Initial testing of a unilateral fixator configuration demonstrated that system rigidity could be increased by maximizing pin separation distance in the fracture component and the number of pins used while minimizing pin separation distance across the fracture site and the sidebar offset distance from bone. A triangulated system composed of half pin frames mounted anteriorly and medially on the tibial aspects and linked by crossbars was devised. Progressive disassembly of the frame was shown to result in progressive decreases in fixator rigidity in all planes.

Fresh autogenous grafts and osteochondral allografts for the treatment of segmental collapse in osteonecrosis of the hip

The treatment of femoral head osteonecrosis and segmental collapse with fresh autogenous grafts and osteochondral allografts is in the experimental stages. The early results suggest that the grafts may be a satisfactory intermediate conservative alternative to radical surgery. Strict adherence to the criteria for selection of candidates for grafting and meticulous surgical technique are essential prerequisites if optimal results are to be achieved. Factors favoring the choice of autologous or allogeneic grafts in osteonecrosis of the hip are the clinically insignificant immunologic reaction and viable hyaline cartilage. Immunosuppressive agents are nonessential. Failure does not preclude artificial resurfacing, endoprosthetic replacement, or total hip arthroplasty.

Benefits and risks of sequential parenteral--oral cephalosporin therapy for suppurative bone and joint infections

Seventy-five infants and children with suppurative skeletal infections were managed with a sequential parenteral-oral regimen of cephalosporin antibiotic therapy. Initially, parenteral antibiotics (cefamandole for 48 patients and cefuroxime for 27 patients) were given for a median of 5 days. Oral therapy was with large doses of cefaclor (150 mg/kg/day) or cephalexin (100 mg/kg/day). Eight patients (11%) had inadequate serum bactericidal activity with cefaclor. Six of them were successfully managed with alternative oral antibiotics, and parenteral therapy resumed in one patient. Chronic disease developed in a child who was continued on oral cloxacillin therapy in spite of absent serum bactericidal activity. It is concluded that oral therapy can be successful for the majority of patients but that it is hazardous and not indicated if careful laboratory monitoring of compliance and serum bactericidal activity cannot be performed.

Surgical treatment of displaced, comminuted fractures of the distal end of the femur

Thirty supracondylar and intercondylar fractures of the femur in twenty-eight patients were reduced and stabilized with ASIF techniques. After an average follow-up of 28.5 months, the results were good or excellent in twenty-four limbs. An extensile surgical exposure with elevation of the tibial tuberosity was used successfully in eight limbs to facilitate the exposure of multiplanar intra-articular fractures. Close attention to the surgical details is necessary to avoid the potential complications of this approach.

Injury to the acetabular triradiate physeal cartilage

Traumatic disruption of the acetabular triradiate physeal cartilage is an infrequent injury. When it occurs during adolescence, subsequent growth changes in acetabular morphology and congruency of the hip joint are unlikely. However, in younger children, especially those who are less than ten years old, acetabular growth abnormality is a frequent complication of this injury and may result in a shallow acetabulum similar to that seen in patients with congenital disease of the hip. By the time of skeletal maturity, disparate growth increases the incongruency of the hip joint and may lead to progressively more severe subluxation of the hip. Acetabular reconstruction may be necessary to correct the gradual subluxation of the femoral head. Variable irregularities of growth at the proximal end of the femur also may occur. In this series, nine patients with triradiate physeal-cartilage injury were classified according to the degree of displacement and the probable type of growth-plate disruption. Two main patterns of injury occurred. The first was a shearing type-1 or 2 growth-mechanism injury, with central displacement of the distal portion of the acetabulum. This injury pattern seems to have a favorable prognosis for continued normal acetabular growth, although premature closure of the triradiate physes may occur. The other pattern appeared to be a crushing type-5 growth-mechanism injury. This type has a poor prognosis, with premature closure of the triradiate physes occurring secondary to the formation of a medial osseous bridge. In either pattern, the prognosis is dependent on the age of the patient at the time of injury and on the extent of chondro-osseous disruption.

The pathological anatomy of Malgaigne fracture-dislocations of the pelvis

Despite renewed interest in the reduction and external fixation of pelvic disruptions, anatomical studies of such injuries are lacking. Of 150 consecutive victims of multiple trauma examined at autopsy, forty-seven (31 per cent) were found to have a pelvic injury. Twenty-six of the thirty-two cadavera that were examined radiographically and dissected had a double break in the pelvic ring (Malgaigne pattern). An anatomical classification based on the degree of posterior injury to the ring is proposed. Anatomical reduction of the posterior fracture-dislocation by external manipulation was impossible in the majority of cadavera because of either ligamentous or osseous interposition, or both, in the sacro-iliac joint, or because of triplane displacement of the hemipelvis.

Unstable hangman's fractures

One hundred and seventy consecutive multiple trauma victims were studied postmortem by radiography and direct inspection at autopsy for the presence of cervical spine injuries. Of the total 38 fractures and/or dislocations, eight had bilateral pedicle fractures of the axis. Only atlanto-occipital dislocations were more frequently encountered. Dissection of six of the eight spines with hangman's fractures showed variable osseous and ligamentous injuries. In only two of the eight cases were significant ligamentous structures sufficiently intact to prevent gross displacement on flexion and extension. In three of the specimens complete laceration of the upper cervical spinal cord was found. Unstable hangman's fractures are a common fatal cervical spine injury in multiple trauma victims.

The management of transpharyngeal gunshot wounds to the cervical spine

Management to prevent cervical osteomyelitis in transpharyngeal gunshot wounds which involve the cervical spine consists of triple endoscopy to identify the pharyngeal injury, anteroposterior and lateral view roentgenograms to localize the injury to the cervical spine, administration of penicillin and gentamicin intravenously, exploration of the neck and repair of pharyngeal wounds, debridement of the cervical spine and external immobilization of the spine for six weeks. This management protocol has proved successful in five patients.

Occult cervical spine injuries in fatal traffic accidents

Post-mortem radiographs as well as careful inspection at autopsy of 100 consecutive traffic accident victims revealed an incidence of cervical spine injury of 24%. All but four of the 24 fractures and/or dislocations were localized to the level between the occiput and the axis. One half of the cases were not clinically suspected of having spine injuries before the detailed postmortem search. Seventeen of the 24 cervical spines were resected en bloc and the pathologic anatomy of the injuries was determined. The high incidence of cervical spine injuries and the anatomic findings at dissection have clinical implications for physicians who manage multiply traumatized patients. The need for immobilization and early radiographic evaluation of patients with cervical spine injuries is emphasized.

Cervical osteomyelitis complicating transpharyngeal gunshot wounds to the neck

Four cases of cervical osteomyelitis complicating transpharyngeal gunshot wounds to the neck are discussed. Thorough debridement of bone and soft tissue, adequate drainage, broad-spectrum antibiotics, and rigid immobilization of the cervical spine are essential for the successful treatment of this complication. Inadequate or delayed treatment may result in prolonged hospitalization, the need for multiple surgical procedures, and possible neurologic deficits.

The pathological anatomy of fatal atlanto-occipital dislocations

Nine atlanto-occipital dislocations were found in postmortem examinations of 112 victims of multiple trauma. Axial traction facilitated roentgenographic identification of the injury. A hyperextension mechanism of injury was suggested by the associated injuries, including submental lacerations and mandibular fractures. Atlanto-occipital dislocations were more frequent in children than in adults. A pure dislocation injury without fracture was identified.