Residual Bone Graft Research Articles

Histology of a fusion mass augmented with demineralized bone matrix for congenital scoliosis

The pseudarthrosis rate after a posterior spinal fusion for congenital scoliosis and kyphoscoliosis is high, between 9.1 and 46.1%. Autogenous iliac crest bone graft is the current gold standard graft material, but is associated with complications that include donor site pain and infection. Demineralized bone matrix (DBM) may be a cost effective, safe, and clinically effective alternative bone graft material. The medical records of a single patient with the diagnosis of congenital scoliosis who had undergone a posterior spinal fusion were reviewed under an institutional review board approved protocol. At 11 months after posterior spinal fusion, bone biopsies were obtained upon routine planned exploration of the spinal fusion site. These samples were sectioned and reviewed by an independent pathologist to assess for bone maturity and the presence of residual allograft bone graft material. The histological specimens that were obtained from the patient showed mature bone with no residual graft material evident in any of the samples. In conclusion, in this particular case, the DBM was fully incorporated into the fusion mass. Although a large clinical trial would be necessary to make generalized conclusions about the use of DBM in the congenital scoliosis population, this histological analysis adds evidence that DBM is incorporated and may aid in obtaining a solid spinal fusion in this difficult population.

Back‐scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphate

To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS). Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material. Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio > or =2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11-2.4) and C, mainly calcium phosphate (S/P< or =0.11; C), which had a mean Ca : P ratio of 1.63+/-0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process. CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone.

B2A Peptide on Ceramic Granules Enhance Posterolateral Spinal Fusion in Rabbits Compared With Autograft

Six groups of 10 animals underwent single level, uninstrumented posterolateral lumbar fusions. Graft sites were implanted with autologous bone, autologous bone plus B2A coated granules with concentrations of 0-, 50-, 100-, or 300 microg/mL, or no graft material. Explanted motion segments were analyzed by Faxitron radiographs, computerized tomography (CT), manual palpation, and histology. The synthetic peptide B2A2-K-NS (B2A) was evaluated as a novel agent for augmenting spinal fusion in a posterolateral, noninstrumented rabbit lumbar spine fusion model. There have been many efforts to increase the rate of posterolateral spinal fusion while, at the same time minimizing, use of autologous bone with its inherent harvest morbidity. B2A coated ceramic granules (0-, 50-, 100-, and 300 microg/mL) were mixed 1:1 with autogenous iliac crest bone and implanted. Autogenous bone alone was used as a positive control. Fusion was assessed at 6 weeks via radiographs and manual palpation. These results were confirmed with histology and CT. Fusion results from palpation and radiographic evaluations were similar. CT and histology confirmed bridging bone across the transverse processes for fused spines. The highest fusion rates were observed in the 100 mug B2A/mL group-89% in comparison to 33% for uncoated granules (0 microg B2A/mL) and 63% for autograft alone. These differences were statistically significant. All investigated B2A concentrations demonstrated increased fusion rates. Fusion masses resulting from the implantation of 100 mug B2A/mL granules demonstrated new woven bone: fused to the transverse processes, within granule pores, bridging bone across the transverse processes, and bridging residual bone graft and granules. It was concluded that each investigated concentration of B2A coated granules in a 1:1 mixture with autograft increased fusion rates in comparison to controls in this rabbit model.

Morphologic Characteristics of Bony Edentulous Jaws

The objective of this study was to examine bone tissue characteristics of edentulous arches and residual ridges in different regions of the human jaws. For the study, 24 maxillary and 99 mandibular completely edentulous dry specimens were examined macroscopically and by linear and caliper measurements. Width and length of the edentulous arches were registered from the molar regions to the crest of the incisor zone. Residual ridges were quantified at the incisor, premolar, and molar regions. Arches and ridges varied in size and shape. A trabecular bone track was present at the edentulous surface. In the maxillary arch, trabecular tissue was external to the cortical palatal vault, and in the mandible, the trabecular bony stretch was inside the cortical plates along the entire edentulous surface of the jaw. Of the ridges, 38% were thin knife-edged. In the maxilla, bone resorption was centripetal, and the crest of the edentulous arch was external to the osseous base of the cranium. In the mandible, resorption was centrifugal, forming an edentulous crest lingual to the mental protuberance anteriorly and to the mandibular base posteriorly. This discrepancy produced a reverse horizontal overlap of the residual crests, where the edentulous maxilla was at the same level or internal to the facing edentulous mandible. This study, performed on 123 human edentulous dry bone specimens, indicates that the edentulous arch and the residual ridge take many forms. At the occlusal surface of the edentulous jaw a trabecular track is the remaining scar after tooth extraction. To accommodate an entire metal osseointegrated implant within the residual bone volume, crest reduction and bone grafts may be required as preprosthetic surgical measures. After tooth loss, maxillary resorption was centripetal and apical, whereas mandibular resorption was centrifugal and also apical, resulting in a reversed horizontal relationship in fully edentulous subjects.

Investigation of Bone Formation using Non-Crystalline Calcium Phosphate Glass in Beagle Dogs

Investigation of Bone Formation using Non-Crystalline Calcium Phosphate Glass in Beagle Dogs

Osseous healing using injectable calcium sulfate-based putty for the delivery of demineralized bone matrix and cancellous bone chips.

Three formulations of injectable calcium sulfate-based putties containing demineralized bone matrix (DBM), 50% DBM/50% cancellous bone (CB) chips, and 30% DBM/70% CB were studied in canines. Four humeral defects per dog were implanted with one of each of the putty formulations while the fourth defect was left untreated. After 6 weeks, the dogs were euthanized. Radiographs and histology showed that the area fraction of new bone in the defects was greater for the three putty formulations than the untreated defects. The area of residual cancellous bone graft remaining in the defects was <10% in both CB putties. Residual calcium sulfate was not apparent in any of the histological sections. We conclude that fast-resorbing calcium sulfate-based putties are effective delivery means of bone graft materials for the successful restoration of bony defects.

Wednesday, October 30, 2001 4:42–5:25 pm Concurrent Session 2B: Lumbar Fusion Complications: 4:42 Residual lower extremity pain after decompression and posterolateral fusion for lumbar spondylolisthesis is often related to bone graft harvest

Purpose of study: Posterior decompression and single-level posterolateral fusion is a well-accepted means of treating symptomatic grade 1–2 lumbar spondylolisthesis. Patients often present with lower extremity (LE) radiculopathy in addition to low back pain. This study was performed to determine whether residual LE pain is secondary to continued radiculopathy or to bone graft site harvest.Methods used: A total of 1,225 patients who had undergone lumbar surgery between 1997 and 2000 were retrospectively studied; 137 patients had undergone single-level posterolateral lumbar fusion for grade 1–2 spondylolisthesis that failed conservative treatment and were available for minimum 2-year follow-up. All patients had iliac crest bone graft site harvest contralateral to the side with the more severe radiculopathy preoperatively. Patients with continued LE discomfort were examined postoperatively to determine whether radicular signs were present and whether tenderness was present directly over the bone graft harvest site.of findings: Twenty-three patients (16.8%) continued to have some LE pain postoperatively. In 19 patients (82.6%) this pain was on the bone graft side. Postoperative physical examination demonstrated that in all 19 of these patients, radicular signs were absent, but tenderness localized to the buttock/posterior iliac crest area was present. Only 1 of the 23 patients had true residual radiculopathy. Fisher's exact test showed that the proportion of patients with residual LE pain and bone graft site findings was significantly greater than the proportion of patients with residual LE pain and radiculopathy (p<.01).Relationship between findings and existing knowledge: Excellent fusion rates and clinical outcomes have been reported for single-level posterior decompression and fusion for grade 1–2 spondylolisthesis. Although resolution of radicular symptoms is more reliable than relief of back pain, some patients still do complain of some LE pain postoperatively. Little is known about whether this is the result of true radiculopathy or the result of bone graft site pain.Overall significance of findings: Radiculopathy after single-level decompression and posterolateral fusion for lumbar grade 1–2 spondylolisthesis is rare. Patients with residual LE pain after this surgery most often have symptoms secondary to iliac crest bone graft harvest. The clinician must be aware of this and perform a thorough examination to prevent unnecessary reoperation for residual LE symptoms.Disclosures: No disclosures.Conflict of interest: No conflicts.

Histologic analysis of implant sites after grafting with demineralized bone matrix putty and sheets.

Grafting to restore lost alveolar bone is frequently used to enable placement of endosseous implants and improve cosmesis. Conflicting reports concerning the osteoinductivity of demineralized bone matrix (DBM) and historical use of synthetic bone graft substitutes has limited the use of DBM in oral and maxillofacial applications. Implant placement after bone grafting provides the unique opportunity to biopsy and histologically evaluate new bone formation. Bone grafting of the mandible or maxilla was performed to fill extraction sockets and restore ridge structures in a consecutive series of eight patients. DBM prepared as malleable putty (Grafton DBM Putty) or flexible sheets (Grafton DBM Flex) was used. Biopsies were taken at reentry, and histologic analysis determined the amount and quality of regenerated bone. Extensive new bone formation and minimal residual bone graft matrix were observed at an average of 5 months postoperative. The pattern of new bone maturity and remodeling varied by patient and the time in situ. Putty and Flex regenerated excellent bone height and width for the placement of dental implants, were easy to handle intraoperatively, and readily conformed to bony defects.