Orthobiologics in the Foot and Ankle.

Many allogeneic biologic materials, by themselves or in combination with cells or cell products, may be transformative in healing or regeneration of musculoskeletal bone and soft tissues. By reconfiguring the size, shape, and methods of tissue preparation to improve deliverability and storage, unique iterations of traditional tissue scaffolds have emerged. These new iterations, combined with new cell technologies, have shaped an exciting platform of regenerative products that are effective and provide a bridge to newer and better methods of providing care for orthopedic foot and ankle patients.

Induction of neural tissue markers by micronized human spinal cord implants.

The osteoinductive capacity of biological noncellular material has been widely recognized. Studies using bone morphogenetic proteins and acellular bone matrix demonstrate that host mesenchymal cells can be readily transformed into osteoprogenitor cells. The current study sought to determine whether another biological noncellular material, human spinal cord matrix, could induce transformation of host cells into a neural lineage. We demonstrate the formation of neural tissue and the expression of neural-specific lineage markers in host cells colonizing implanted spinal cord fragments and adjacent tissue along with the lack of expression of nonneural lineage markers. These studies demonstrate that the inductive capacity of biological noncellular material is not limited to the osteogenic lineage and suggest that acellular spinal cord matrix could be used to generate host-derived cells for use in neural repair and regeneration.

Carboxyl-modified single-wall carbon nanotubes improve bone tissue formation in vitro and repair in an in vivo rat model.

The clinical management of bone defects caused by trauma or nonunion fractures remains a challenge in orthopedic practice due to the poor integration and biocompatibility properties of the scaffold or implant material. In the current work, the osteogenic properties of carboxyl-modified single-walled carbon nanotubes (COOH-SWCNTs) were investigated in vivo and in vitro. When human preosteoblasts and murine embryonic stem cells were cultured on coverslips sprayed with COOH-SWCNTs, accelerated osteogenic differentiation was manifested by increased expression of classical bone marker genes and an increase in the secretion of osteocalcin, in addition to prior mineralization of the extracellular matrix. These results predicated COOH-SWCNTs' use to further promote osteogenic differentiation in vivo. In contrast, both cell lines had difficulties adhering to multi-walled carbon nanotube-based scaffolds, as shown by scanning electron microscopy. While a suspension of SWCNTs caused cytotoxicity in both cell lines at levels >20 µg/mL, these levels were never achieved by release from sprayed SWCNTs, warranting the approach taken. In vivo, human allografts formed by the combination of demineralized bone matrix or cartilage particles with SWCNTs were implanted into nude rats, and ectopic bone formation was analyzed. Histological analysis of both types of implants showed high permeability and pore connectivity of the carbon nanotube-soaked implants. Numerous vascularization channels appeared in the formed tissue, additional progenitor cells were recruited, and areas of de novo ossification were found 4 weeks post-implantation. Induction of the expression of bone-related genes and the presence of secreted osteopontin protein were also confirmed by quantitative polymerase chain reaction analysis and immunofluorescence, respectively. In summary, these results are in line with prior contributions that highlight the suitability of SWCNTs as scaffolds with high bone-inducing capabilities both in vitro and in vivo, confirming them as alternatives to current bone-repair therapies.

A comparison of two microbial detection methods used in aseptic processing of musculoskeletal allograft tissues.

Tissues from 78 musculoskeletal donors were concurrently tested for microorganisms using both a swab and liquid culture method. An aggregate total of 20 organisms were detected by both methods. The swab detected 4/20 organisms while the liquid culture detected 18/20 organisms. The swab method yielded sensitivity and negative predictive values of 20 and 92.3%, respectively. Comparatively, the liquid culture displayed a sensitivity of 90% and a negative predictive value of 99%. These results clearly demonstrate that the liquid culture method is superior to swab cultures in microbial detection. Additional studies are necessary to determine the optimal culture conditions for different types of tissues when utilizing the liquid culture method.

Use of corticocancellous allogeneic bone blocks for augmentation of alveolar bone defects.

PURPOSE: The use of autogenous block bone grafts in bone regeneration procedures for alveolar ridge augmentation can be limited by donor site morbidity and complications. The purpose of the present study was to evaluate the efficacy of allogeneic corticocancellous iliac block grafts used for ridge augmentation prior to implant placement. MATERIALS AND METHODS: Forty-one patients with severe ridge volume deficiency underwent augmentation using allogeneic corticocancellous iliac block bone grafts. After rigid fixation of the graft, the site was covered with a freeze-dried allogeneic dura mater membrane, and the wound was closed with tension-free suturing. Implants were placed 3 to 4 months after surgery. Three to 6 months after implant placement, panoramic radiographs were taken and implants were uncovered for prosthetic restoration. RESULTS: Of the 57 grafts placed, one showed 2.5 mm of resorption at the superior buccal aspect of the graft. No other clinical problems were observed. The block grafts were clinically well integrated into the recipient sites and the augmented bone remained stable throughout the implant placement procedures. Of the 84 implants placed, only one failed to integrate. CONCLUSION: These results demonstrate that the use of allogeneic corticocancellous iliac block bone grafts in conjunction with guided bone regeneration principles is a viable alternative to autogenous grafts in selected patients with alveolar ridge deficiencies.

Proximal humerus reconstructions for tumors.

UNLABELLED: The optimal method for reconstructing the proximal humerus in patients with tumors is controversial. To determine functional outcomes and complication rates after different types of reconstructions, we reviewed a consecutive series of 49 patients who underwent proximal humerus resection and osteoarticular allograft (17 patients), allograft-prosthetic composite (16), or endoprosthetic (16) reconstruction. Operative indications included primary malignancies (24 patients), metastatic disease (19), and benign aggressive disease (six). Implant revision was more common after osteoarticular reconstruction (five of 17) than after allograft-prosthetic composite (one of 16) or endoprosthetic (zero of 16) reconstructions. At a minimum followup of 24 months (median, 98 months; range, 24-214 months) in surviving patients, Musculoskeletal Tumor Society functional scores averaged 79% for the allograft-prosthetic composite, 71% for the osteoarticular allograft, and 69% for the endoprosthetic reconstruction cohorts. Shoulder instability was associated with abductor mechanism compromise and was more common after endoprosthetic reconstruction. Allograft fractures occurred in 53% of patients receiving osteoarticular allografts. We recommend allograft-prosthetic composite reconstruction for younger patients with primary tumors of bone and endoprosthetic reconstruction for older patients with metastatic disease. Because of the unacceptable complication rate, we do not recommend osteoarticular allograft reconstruction for routine use in the proximal humerus. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Cancellous and cortical microparticulate allograft for dental implantation: an experimental study in non-human primates.

BACKGROUND: : A comparison of freeze-dried cancellous and cortical particulate bone allograft was made using a non-human primate model. METHODS AND MATERIALS: : Microparticulate bone allograft (90-300 µm size) made from either cortical or cancellous bone was used to pack standard bone defects in the lower extremities of baboons, Papio hamadryas. Bone allografts were aseptically processed and freeze dried. Bone allografts were prepared from animals other than those included in this study. Six weeks after bone grafting, the animals were killed. Extremities with defects were radiographed. The bone preparations were sectioned with a diamond saw, inspected grossly, photographed, then fixed, and subjected to histologic and histomorphometric analysis. RESULTS: : Cylindrical bone defects were healed in all animals. No differences in the healing patterns and new bone formation were detected between defects filled with cortical and cancellous microparticulate bone preparations. CONCLUSION: : Either cortical or cancellous microparticulate bone preparations can be used with equal effectiveness to promote bone regeneration in confined bone defects.

Microparticulate cortical allograft: an alternative to autograft in the treatment of osseous defects.

Benign bone tumors are commonly diagnosed and treated. Following tumor removal, the defect in the bone can be filled with auto- or allografts, (degradable) bone substitutes or non-degradable polymethylmethacrylate. The ideal substitute for this purpose should provide immediate structural support and readily incorporate into bone over a short period of time. Experimentally, microparticulate allograft has been shown to incorporate quickly in metaphyseal and metadiaphyseal cortico-cancellous defects in primates [1]. Using a combination of small allogeneic cortical graft particles (< 250 microm), bone defects were filled following intralesional excision in 97 consecutive patients with benign and low grade malignant tumors and tumor-like conditions of bone. The clinical results and rate of radiographic incorporation and osseous consolidation were recorded and analyzed. These patients underwent 104 procedures in which osseous defects were packed with microparticulate allograft. The follow-up was from 23 to 49 months. There were 94 (90.3%) closed defects and 10 (9.7%) open defects. The average size of the grafted defect was 42.8 cm(3) (0.48 - 315.0 cm(3)). Internal fixation was used in 11 of the 104 procedures (10.6 %). Radiographically, incorporation was observed in 91% of patients and consolidation in 60%. There were eleven failures (10.6 %), eight (72 %) due to tumor recurrence. Seven of eight patients with tumor recurrence underwent a second resection and grafting procedure that resulted in allograft incorporation and defect healing. There were two deep infections requiring debridement with retention of the graft; both resolved with satisfactory healing.Both incorporation and consolidation were observed in over 90% of patients with a low rate of complications. The use of small-particle cortical allograft proved to be an effective alternative to autogenous bone graft in patients with metaphyseal and metadiaphyseal surgical bone defects.

Changes in vertebral bodies adjacent to acutely narrowed intervertebral discs: observations in baboons.

STUDY DESIGN: The study used nonhuman primates to investigate changes in the vertebral bodies adjacent to acutely narrowed intervertebral discs. OBJECTIVE: To describe changes in the vertebral bodies adjacent to acutely narrowed intervertebral discs in the lumbar spine. SUMMARY OF BACKGROUND DATA: Alterations in the intervertebral disc are known to affect the adjacent vertebral bodies. The consequences of sudden narrowing of the intervertebral disc on adjacent vertebral bodies have not been studied. We studied the effect of decompression of the normal primate IVD on the adjacent bone. The use of larger primates was appropriate for this study since the biomechanics of the spine on these animals mimics the human spine. METHODS: Experiments were performed on 36 adult baboons. The intervertebral discs were decompressed with enzymes or surgically. On death at 4, 12, and 24 weeks, the spines were radiographed, sectioned, and photographed. The changes in the subchondral vertebral bone were documented. Segments were examined histologically. RESULTS: At 24 weeks, 8 of 10 enzyme-injected discs (and at 14 weeks, 3 of 3 of the discectomies) contained semicircular yellowish-white areas in the bone adjacent to the narrowed discs. These showed bone marrow cell depletion and microfractures of trabecular bone. The lesions were most extensive following surgical nucleotomy. These changes were not seen following bone graft (0 of 4) or spacer replacement (0 of 4) of the intervertebral discs. CONCLUSION: Alteration in vertebral bodies adjacent to suddenly narrowed intervertebral discs suggest trabecular bone response to physical stress. This is manifested by microfractures and bone marrow depletion.

Comparison of frozen and freeze-dried particulate bone allografts.

Freeze-dried and frozen particulate bone allografts are used interchangeably on the assumption that the biologic behavior of these grafts is similar. Dissimilarities in biologic behavior and differences in the rate and extent of bone incorporation of freeze-dried and frozen particulate grafts were demonstrated in a comparative study using a non-human primate model. Freeze-dried particulate allografts induced new bone formation and healing of the osseous defects much faster than the frozen allografts.

Distal tibial osteoarticular allografts.

Osteoarticular allografts can be used for limb reconstruction following tumor excision. Most commonly, the distal femur, proximal tibia and distal radius have been studied, while distal tibial allografts receive only sporadic mention in the literature. We evaluated the functional outcomes of distal tibial allografts used in tumor reconstruction. Following FDA guidelines and using a questionnaire, we surveyed operating surgeons on the outcomes of 29 distal tibial allografts used to reconstruct osseous defects secondary to benign and malignant tumors. Twelve patient questionnaires were returned revealing nine complications in eight patients. These included nonunions (three), fracture (two), arthrosis (two), and delayed union (two). There were no reported infections. Two patients died of their disease. The average rating using the Musculoskeletal Tumor Society (MSTS) score was 67.3%. The 10 living patients had an average rating of 72.4%. Distal tibial osteoarticular allografts offer acceptable functional results when used in tumor reconstruction. Difficulties achieving union (delayed or nonunion) between the host and the graft appears the most common complication of this technique.

Particulate bone allograft incorporation in regeneration of osseous defects; importance of particle sizes.

Packing of bone defect with particulate allografts is a commonly performed clinical procedure. However, the ideal size of bone particles used to fill bone defects is ill-defined. For this reason the study of biology of bone allografts with different particle sizes has been performed. Standard size bone defects in the femur and the tibia of experimental animals were filled with freeze-dried cortical bone allografts with particle sizes of 1-2mm, 800-500mum, 500-300mum, 300-90mum, 250-125mum, 125-106mum, 106 to 75mum and 75-25mum. Unfilled defects and those filled with autologous bone served as controls. Cortical bone was chosen because it produced better clinical results than did cancellous bone. Likewise freeze-dried particulate bone effected more rapid healing than did frozen bone. Numerical scores were assigned to each defect based on the gross, radiographic and histomorphometric studies. Particles in the range of 300 to 90 microns produced rapid healing by direct ossification. Particles below 100microm had a significantly reduced osteogenic potential. Particles in the range of 75-25mum failed to heal the defects all together. Healing of defects packed with particles larger than 300mum was slower than with 300 - 90 mum grafts. Rapid healing of bone defects packed with particulate bone allografts in the range of 300 to 90mum indicates such allografts can be used effectively in the filling of bone defects. This is of clinical relevance.

Transplantation of osteochondral allografts after cold storage.

BACKGROUND: Transplantation of fresh osteochondral allografts stored at hypothermia into knee cartilage defects is a common procedure; however, the length of time that allografts can be stored prior to transplantation is controversial and has been determined, in part, by the results of vital stain uptake by chondrocytes. This study was performed to further define the limits of allograft storage. METHODS: Articular cartilage from six cadavers was stored for up to fifty-one days in tissue-culture media, and histologic sections were evaluated histomorphometrically to quantify the loss of chondrocytes. Samples of the cartilage were also placed into tissue culture to assess cell growth. Animal studies were performed in parallel on sixteen adult baboons with osteochondral allografts transplanted into the medial femoral condyle. Prior to transplantation, all allografts were stored in RPMI-1640 with 10% fetal calf serum at 4 degrees to 6 degrees C for up to eighty-five days. The transplants were graded on their gross and histological appearance, as well as their histochemical properties. RESULTS: Many of the human samples stored at hypothermia in culture media for up to forty days retained some recognizable chondrocytes, but morphometry showed a gradual, significant decrease in the number of chondrocytes after nine days (p = 0.001). In addition, the cell outgrowth occurred from all specimens stored for up to fifteen days but not in samples stored for longer than thirty-four days. In animal studies, transplanted allograft cartilage that had been stored for less than eighteen days looked smooth and glistening, but grafts stored for over twenty-one days were pale, pitted, fragmented, or yellow, and chondrocytes were absent. CONCLUSIONS: Time-dependent loss of chondrocytes in articular cartilage stored at hypothermia, especially in specimens stored for longer than fifteen to twenty days, was observed in this study. Cartilage allografts transplanted into nonhuman primates after twenty-one days of storage underwent more severe degenerative changes than allografts that had been stored for less than twenty-one days. These findings suggest caution when transplanting cartilage stored at hypothermia for over twenty days.

Salvage of failed massive allograft reconstruction with endoprosthesis.

UNLABELLED: A subset of osteoarticular allograft reconstructions after tumor resection ultimately will fail in patients achieving long-term survival. There are several alternative surgical approaches to revising these reconstructions. We retrospectively evaluated the outcome of 20 patients who had allograft reconstruction with a modular endoprosthesis. All patients had a failed massive allograft (average length, 15.7 cm) after tumor resection about the shoulder and knee. The reasons for original allograft failure were fracture (14 patients), infection (five patients), and both (one patient). Followup of the patients averaged 159.7 months (range, 63-293 months) after allograft reconstruction and 77 months (range, 24-234 months) after endoprosthetic revision. The average number of operative procedures each patient had was 4.1 (range, 2-15 procedures). Two patients had amputations for resistant periprosthetic infections. A successful revision procedure was accomplished in 80% of the patients, and 90% of the patients retained functional limbs at recent followup. The predicted 5-, 10-, and 15-year survivals were 92%, 55% and 28% respectively. Musculoskeletal Tumor Society scores averaged 76% (range, 60-93.3%). When used to salvage massive allograft failure from infection and fractures, endoprosthetic revision preserves limb function with minimal complications. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Effect of hydrogen peroxide on osteoinduction by demineralized bone.

The osteoinductive capacity of demineralized bone matrix (DBM) has led to wide use of this material for surgical reconstruction. Preparation of DBM often includes sterilization with ethylene oxide, disinfection with various chemical agents, or irradiation. Exposure to hydrogen peroxide (H2O2) is used for both sterilization and bleaching of bone, the latter primarily for cosmetic reasons. We investigated the effect of H2O2, on the osteoinductive capacity of DBM. Cortical bone implants prepared from rat femurs were placed into 3% H2O2 solution. Control specimens were not exposed to H2O2. Bones were then lipid-extracted, demineralized, sterilized with ethylene oxide, and freeze-dried in an identical manner. Allografts were implanted into rat hosts for 1 to 3 weeks. Osteoinduction proceeded rapidly in implants not exposed to H2O2, with chondrocytes and new bone appearing in the implant. After 3 weeks, perforations in the implant were largely replaced with new bone. In contrast, osteoinduction did not occur in implants treated with H2O2. Perforations in H2O2-treated implants were filled with vascularized fibrous tissue, but no cartilage or bone. These findings reveal that H2O2 used for disinfection or bleaching of DBM can abolish its osteoinductive capacity in rats.

Bone and tissue allograft use by orthopaedic surgeons.

The purpose of our study was to determine the involvement of orthopaedic surgeons in the process of acquiring allografts they transplant. A questionnaire regarding allograft acquisition and use was directed to 340 hospitals. In approximately 85% of the institutions, nonorthopaedic personnel selected and acquired the allografts. In most, those responsible for providing surgeons with allografts had little or no knowledge of the practices of tissue banking and allograft transplantation biology. In about 15% of the hospitals, the surgeon was involved in the selection of the source of allografts. It is imperative that orthopaedic surgeons who transplant bone and tissue allografts become actively involved in determining the source and processing of tissue transplants they place in their patients.

Recurrent aggressive chondrosarcoma of the middle phalanx of the index finger: excision and reconstruction with an osteocartilaginous allograft.

INTRODUCTION: Chondrosarcomas are malignant tumours and need to be treated aggressively including ablative surgery. Bovée et al. and Mankin have recently drawn attention to a less aggressive behaviour of chondrosarcomas of the phalanges compared with those of other localizations including the metacarpals. MATERIALS AND METHODS: An 12 year follow-up of a patient with a chondrosarcoma of the middle phalanx of the index finger is presented. The lesion was curetted initially, and a repeat curettage was performed 4 years later. Finally, 8 years later the phalanx was excised and reconstructed with an osteocartilaginous allograft. Histologically, the lesion changed from a chondrosarcoma grade I to grade II. RESULT: The patient continues to be free of recurrence and metastases 4 years after the final resection. CONCLUSION: The potential for systemic disease of chondrosarcomas of the phalanges is probably much lower than in chondrosarcomas of other localizations, and therefore digit-sparing techniques may be considered rather than ablative procedures.

Blood and marrow cultures as indicators of bone contamination in cadaver donors.

Of 770 cadaver bone donors evaluated, 185 had positive blood or ilium marrow aspirate cultures. These donors were matched with an immediately preceding or subsequent donor with negative blood and marrow cultures. Donors with cultures positive for skin contaminants only were not included in the study. Samples of the blood and bone marrow, surface swab cultures, and cultures of tissue samples of the excised skeletal tissues were obtained at the time of tissue procurement. There were 88 (48%) donors with similar microbial species recovered from the blood and ilium marrow. These donors had a higher rate of positive bone cultures (30%) than donors with positive blood (15%) or marrow cultures only (11%) or donors with negative blood and marrow culture results (7.3%). Recovery of similar isolates from the blood and marrow had a positive predictive value of 72% for the isolation of the same types of organisms from the excised tissues compared with 38% for donors with positive blood cultures only. Although not absolute predictors of tissue contamination, combined blood and bone marrow cultures were more reliable indicators of tissue contamination than blood cultures alone.

Allograft reconstruction after resection of malignant tumors of the scapula.

The oncologic and functional outcomes of six patients who had scapular allograft reconstruction after scapulectomy for malignant tumors were reviewed. Five patients had Stage IIB and one patient had Stage IB tumors. Total scapulectomy was done in five patients, and partial scapulectomy (glenoid and neck) was done in one patient. Frozen glycerolized scapular allografts were implanted and fixed with plates and screws. The scapular muscles were reattached to the allograft. Tendon reconstruction to replace the excised muscles was done in two patients. The patients were followed up for an average of 3.8 years (range, 2-6 years). Cosmesis, elbow, and hand function were good in all patients. There were no infections, nonunions, or shoulder dislocations. One patient fractured the body of the allograft after a fall. One patient had local recurrence and had scapulectomy 5 years postoperatively. Two patients died 3 and 5 years postoperatively with lung metastases but with functioning grafts. The mean functional result using the Musculoskeletal Tumor Society functional score was 82 (range, 77-87). In this series, scapular allograft reconstruction restored cosmesis, shoulder stability, and function. Preservation or reconstruction of rotator cuff muscles is recommended.

A study of retrieved allografts used to replace anterior cruciate ligaments.

PURPOSE: The purpose of the study was the examination of retrieved whole anterior cruciate ligament (ACL) replacement grafts to determine the rate and the extent of cellular replacement and remodeling of the grafts. TYPE OF STUDY: Gross and histopathologic examination of specimens. METHODS: Nine specimens of ACL replacement allografts and 1 autograft were obtained at autopsy and surgical procedures. RESULTS: Examination of these specimens from 20 days to 10 years after transplantation revealed a pattern of revascularization similar to that reported in previous biopsy studies. However, examination of the entire allografts showed that, at 2 years after transplantation, the central portions of the grafts remained acellular and that complete attachment was not present, but was found in a 3.5-year post-transplantation specimen. CONCLUSIONS: Because attachment of the graft to bone tunnel walls required over 2 years, the tunnel remodeling may be explained on a mechanical basis. The remodeling of ACL replacement grafts is a gradual or slow process. Complete remodeling and cellular replacement of the entire graft may require 3 years or longer.