Synergistic effects of HBO and PRP improve bone regeneration with autologous bone grafting

Bone defects remain a challenge for patients and orthopaedic surgeons. Autologous transfer of cancellous bone grafts remains the standard of care. However, in recent years various osteoinductive substitute materials, such as platelet rich plasma (PRP) and hyperbaric oxygen therapy (HBO) have been shown to improve bone healing. This study evaluates the effects of a combined application of PRP and HBO with autologous bone grafting in an animal model.In 48 New Zealand White rabbits bone defects at the radius were filled with autologous bone harvested at the iliac crest. This was combined with application of autologous PRP and/or HBO treatment for the duration of this study. After 3 and 6 weeks histomorphometric, immunohistochemical and radiologic evaluations were performed.All animals tolerated the treatment well. Improved bone regeneration was shown in all groups at 6 weeks compared to 3 weeks. Additional application of PRP and HBO resulted in an increase in new bone formation and increased neovascularization at 3 and 6 weeks. There was no statistical significant difference between PRP and HBO application in these regards. A combinatory use of PRP and HBO resulted in an increased bone regeneration and neovascularization compared to all other groups.This study provides evidence for an improvement of bone regeneration with the combinatory application of PRP and HBO to autologous cancellous bone grafts in a model of weight bearing bone defects in rabbits. Also synergistic effects of these two measures on angiogenesis were evident.     

Spatiotemporal Analyses of Osteogenesis and Angiogenesis via Intravital Imaging in Cranial Bone Defect Repair

Osteogenesis and angiogenesis are two integrated components in bone repair and regeneration. A deeper understanding of osteogenesis and angiogenesis has been hampered by technical difficulties of analyzing bone and neovasculature simultaneously in spatiotemporal scales and in 3D formats. To overcome these barriers, a cranial defect window chamber model was established that enabled high‐resolution, longitudinal, and real‐time tracking of angiogenesis and bone defect healing via multiphoton laser scanning microscopy (MPLSM). By simultaneously probing new bone matrix via second harmonic generation (SHG), neovascular networks via intravenous perfusion of fluorophore, and osteoblast differentiation via 2.3‐kb collagen type I promoter‐driven GFP (Col2.3GFP), we examined the morphogenetic sequence of cranial bone defect healing and further established the spatiotemporal analyses of osteogenesis and angiogenesis coupling in repair and regeneration. We showed that bone defect closure was initiated in the residual bone around the edge of the defect. The expansion and migration of osteoprogenitors into the bone defect occurred during the first 3 weeks of healing, coupled with vigorous microvessel angiogenesis at the leading edge of the defect. Subsequent bone repair was marked by matrix deposition and active vascular network remodeling within new bone. Implantation of bone marrow stromal cells (BMSCs) isolated from Col2.3GFP mice further showed that donor‐dependent bone formation occurred rapidly within the first 3 weeks of implantation, in concert with early angiogenesis. The subsequent bone wound closure was largely host‐dependent, associated with localized modest induction of angiogenesis. The establishment of a live imaging platform via cranial window provides a unique tool to understand osteogenesis and angiogenesis in repair and regeneration, enabling further elucidation of the spatiotemporal regulatory mechanisms of osteoprogenitor cell interactions with host bone healing microenvironment. © 2015 American Society for Bone and Mineral Research.     

The missing effect of human recombinant Bone Morphogenetic Proteins BMP-2 and BMP-7 in surgical treatment of aseptic forearm nonunion

IntroductionIn this cohort study, the surgical revision concept of open compression plating and autologous bone grafting with and without additional application of BMP for treatment of aseptic ulna and/or radius shaft nonunion was evaluated. The purpose was to evaluate the clinical and radiological outcome, and to determine any difference in osseous healing, range of time between revision surgery and bone healing, and postoperative complications between the cohort groups.Patients and methodsBetween 01/2005 and 03/2015, a prospective, randomised, controlled cohort study was performed in a Level I Trauma Centre. Forty-nine patients were treated with the diagnosis of aseptic diaphyseal ulnar and/or radial shaft nonunion using compression plating and autologous bone grafting. Additional biological augmentation using BMP-2 or BMP-7 was performed in 24 patients. Clinical and radiological follow-up was performed six weeks, three and six months after revision surgery in accordance to the system by Anderson.ResultsThe study group consisted of 38 men and 11 women with a median age of 44 years (range 19–77). Twenty-four out of 49 patients obtained compression plating either with autologous iliac crest bone grafting (11/24 patients) or cancellous bone grafting (13/24 patients) and additional application of BMP-2 (4/24 patients) or BMP-7 (20/24 patients). The remaining 25 patients did not receive any additional application of BMP, but autologous bone grafting. The median follow-up was 15 months (range 6–54 months). Forty-six out of 49 nonunion healed within 12 months after revision surgery with a median time to union of six months. The clinical outcome, as assessed using the system by Anderson, as well as osseous healing, duration of time interval between revision surgery and bone healing, and postoperative complications did not demonstrate significant differences between the cohort groups.DiscussionAtrophic/oligotrophic forearm nonunion healed irrespective of additional application of BMP combined with autologous bone grafting. For successful treatment, radical resection of fibrous nonunion tissue and internal compression plate fixation is required with the aim of achieving high degree of rigid stability. Also, correction of angular deformities, restoration of length, and precise axial alignment of the distal radio-ulnar joint are mandatory prerequisites to successfully achieve bone healing.     

Mechanical and radiological assessment of the influence of rhTGFbeta-3 on bone regeneration in a segmental defect in the ovine tibia: pilot study.

Limitations in the use of autologous bone graft, which is the gold standard therapy in bone defect healing, drive the search for alternative treatments. In this study the influence of rhTGFbeta-3 on mechanical and radiological parameters of a healing bone defect in the sheep tibia was assessed. In the sheep, an 18-mm long osteoperiosteal defect in the tibia was treated by rhTGFbeta-3 seeded on a poly(L/DL-lactide) carrier (n = 4). In a second group (n = 4), the defect was treated by the carrier only, in a third group (n = 4) by autologous cancellous bone graft, and in a fourth group (n = 2) the defect remained blank. The healing process of the defect was assessed by weekly in vivo stiffness measurements and radiology as well as by quantitative computed tomographic assessment of bone mineral density (BMD) every 4 weeks. The duration of the experiment was 12 weeks under loading conditions. In the bone graft group, a marginally significant higher increase in stiffness was observed than in the PLA/rhTGFbeta-3 group (p = 0.06) and a significantly higher increase than in the PLA-only group (p = 0.03). The radiographic as well as the computed tomographic evaluation yielded significant differences between the groups (p = 0.03), indicating the bone graft treatment (bone/per area, 83%; BMD, 0.57 g/cm(3)) performing better than the PLA/rhTGFbeta-3 (38%; 0.23 g/cm(3)) and the PLA-only treatment (2.5%; 0.09 g/cm(3)), respectively. Regarding the mechanical and radiological parameters assessed in this study, we conclude that rhTGFbeta-3 has a promoting effect on bone regeneration. However, under the conditions of this study, this effect does not reach the potential of autologous cancellous bone graft transplantation.     

Hyperbaric oxygen results in an increase in rabbit calvarial critical sized defects.

OBJECTIVE: This study was undertaken to evaluate whether the effects of hyperbaric oxygen (HBO) therapy could alter the critical size for spontaneous healing of a bone defect in the rabbit calvarial model. STUDY DESIGN: An animal trial of 12 weeks duration was conducted using 20 New Zealand white rabbits, which were randomly divided into 2 groups of 10 animals each. Calvarial defects were created in the parietal bones of each animal bilaterally. Defects were critical-sized, 15 mm on one side and supra-critical-sized, 18 mm on the contralateral side. Group 1 received a 90-min HBO treatment sessions at 2.4 absolute atmospheric pressure (ATA) per day for 20 consecutive days. Group 2 served as a control without any HBO treatment sessions. Five animals in each group were sacrificed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens, post-sacrifice radiographs, as well as histomorphometric analysis to compute the amount of regenerated bone within the defects. ANOVA and paired sample t test were used for statistical analysis. RESULTS: Both radiographic analysis and histomorphometric analysis demonstrated that HBO-treated animals had significantly more new bone within their defects compared with the control group (P < .001). There was no statistically significant difference between the percentage of new bone forming in the 15-mm and 18-mm HBO-treated defects. There was no difference between the 6-week and the 12-week HBO-treated groups. HBO is effective in enhancing the bony healing of full thickness critical sized as well as supra-critical-sized defects in the rabbit calvarial model. CONCLUSION: Bone regeneration was significantly greater in the HBO-treated animals regardless of the defect size. HBO may have increased the diameter of the rabbit critical-sized calvarial defect to more than 18 mm.     

Two‐step stem cell therapy improves bone regeneration compared to concentrated bone marrow therapy

Adult stem cells are a promising tool to positively influence bone regeneration. Concentrated bone marrow therapy entails isolating osteoprogenitor cells during surgery with, however, only low cells yield. Two step stem cell therapy requires an additional harvesting procedure but generates high numbers of progenitor cells that facilitate osteogenic pre‐differentiation. To further improve bone regeneration, stem cell therapy can be combined with growth factors from platelet rich plasma (PRP) or its lysate (PL) to potentially fostering vascularization. The aim of this study was to investigate the effects of bone marrow concentrate (BMC), osteogenic pre‐differentiation of mesenchymal stromal cells (MSCs), and PL on bone regeneration and vascularization. Bone marrow from four different healthy human donors was used for either generation of BMC or for isolation of MSCs. Seventy‐two mice were randomized to six groups (Control, PL, BMC, BMC + PL, pre‐differentiated MSCs, pre‐differentiated MSCs + PL). The influence of PL, BMC, and pre‐differentiated MSCs was investigated systematically in a 2 mm femoral bone defect model. After a 6‐week follow‐up, the pre‐differentiated MSCs + PL group showed the highest bone volume, highest grade of histological defect healing and highest number of bridged defects with measurable biomechanical stiffness. Using expanded and osteogenically pre‐differentiated MSCs for treatment of a critical‐size bone defect was favorable with regards to bone regeneration compared to treatment with cells from BMC. The addition of PL alone had no significant influence; therefore the role of PL for bone regeneration remains unclear. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1318–1328, 2019.     

The effect of hyperbaric oxygen therapy on spinal fusion: using the model of posterolateral intertransverse fusion in rabbits

BACKGROUND: The purpose of this study is to evaluate the facilitating effect of hyperbaric oxygen (HBO) on posterolateral intertransverse fusion using a validated rabbit model. METHODS: Twenty-four male New Zealand rabbits underwent posterolateral intertransverse fusion at L5-L6 with autogenous iliac bone graft. They were evenly divided into two groups: the HBO group and the normal room air (RA) group. Each group had six rabbits killed at 4 weeks and 8 weeks, respectively. The rabbits in the HBO groups were treated with 100% oxygen at 2.5 atm for 2 hours a day. After being killed, all rabbits were subjected to radiographic examination, manual testing, and torsional loading to evaluate the results of spinal fusion. RESULT: Radiographic union of intertransverse fusion areas at 4-week RA, 4-week HBO, 8-week RA, and 8-week HBO were 2 of 12, 7 of 12, 7 of 12, and 10 of 12, respectively. Solid union proven by manual palpation was found to be zero of six, three of six, four of six, and five of six of the cases, respectively. The average peak torsional momentums were 2120.2, 2576.5, 2661.6, and 3079.8 N-mm, respectively. Spinal fusion was significantly improved in the HBO groups at both 4 weeks and 8 weeks. CONCLUSION: The results of this study suggest that intermittent hyperbaric oxygen therapy will hasten the bone healing process and improve the fusion rate as compared with the non-HBO group.     

关节镜下双袢固定自体髂骨修复合并严重骨缺损的Bankart损伤临床疗效分析

目的 探讨关节镜下双袢固定自体髂骨修复合并严重骨缺损的Bankart损伤患者肩关节临床功能改善及肩胛盂骨缺损修复情况.方法 回顾性分析2015年7月至2018年7月在南方医科大学第三附属医院运动医学科采用关节镜下双袢固定自体髂骨植骨术治疗的17例合并严重骨缺损的Bankart损伤患者.在术前和术后使用美国肩肘外科协会(...     

复发性肩关节前脱位伴骨缺损的治疗进展

复发性肩关节前脱位伴骨缺损是肩关节常见疾病之一。如何有效地修复关节盂骨缺损,降低肩关节脱位复发率是临床医师关注的问题。骨移植术能够发挥骨刺激作用,促进骨再生和骨重塑,恢复关节盂的正常解剖结构。其中,Bristow-Latarjet术是治疗复发性肩关节脱位的经典术式,Latarjet术能够修复更大的关节盂骨缺损,但对手术医师的操作要求更高;自体髂骨移植术是Latarjet术失败后翻修的首选方案;骨软骨移植术(自体和异体)在重建原始关节面和预防关节退行性改变方面有一定的优势,但自体骨软骨移植术会造成二次损伤,而异体骨软骨移植术的免疫排斥难以避免。随着复合材料的改进,对骨再生、重塑机制的探究,以及结合骨移植术的优缺点,组织工程技术将来有可能成为治疗关节盂骨缺损的重要方法。     

Combination therapy with intra‐articular injection of mesenchymal stem cells and articulated joint distraction for repair of a chronic osteochondral defect in the rabbit

The present study investigated intra‐articular injection of bone‐marrow‐derived mesenchymal stem cells (MSCs) combined with articulated joint distraction as treatment for osteochondral defects. Large osteochondral defects were created in the weight‐bearing area of the medial femoral condyle in rabbit knees. Four weeks after defect creation, rabbits were divided into six groups: control group, MSC group, distraction group, distraction + MSC group, temporary distraction group, and temporary distraction + MSC group. Groups with MSC received intra‐articular injection of MSCs. Groups with distraction underwent articulated distraction arthroplasty. Groups with temporary distraction discontinued the distraction after 4 weeks. The rabbits were euthanized at 4, 8, and 12 weeks after treatment except temporary distraction groups which were euthanized at only 12 weeks. Histological scores in the distraction + MSC group were significantly better than in the control, MSC group or distraction group at 4 and 8 weeks, but showed no further improvement. At 12 weeks, the temporary distraction + MSC group showed the best results, demonstrating hyaline cartilage repair with regeneration of the osteochondral junction. In conclusion, joint distraction with intra‐articular injection of MSCs promotes early cartilage repair, and compressive loading of the repair tissue after temporary distraction stimulates articular cartilage regeneration. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1466–1473, 2015.     

Transplanted blood-derived endothelial progenitor cells (EPC) enhance bridging of sheep tibia critical size defects

The angiogenic events that accompany bone regeneration function as a “limiting factor” and are the primary regulatory mechanisms that direct the healing process. The general aim of this study was to test whether blood-derived progenitor cells that have endothelial characteristics (EPC), when applied to a large segmental defect, would promote bone regeneration. We established a critical-sized gap platform in sheep tibiae. Our model system takes advantage of the physiological wound healing process that occurs during the first two weeks following injury, and results in the gap being filled with scar tissue. EPC were expanded ex-vivo and 2 × 10⁷ cells/0.2 ml were implanted into a wedged-shaped canal excavated in the fibrotic scar tissue. Sham treated sheep served as controls. Bone regeneration was followed every two weeks for three months by X-ray radiography. At the end of the experimental period, the regenerating segments were subjected to micro-computed tomographic (μCT) analysis. While minimal bone formation was detected in sham-treated sheep, six out of seven autologous EPC-transplanted sheep showed initial mineralization already by 2 weeks and complete bridging by 8–12 weeks post EPC transplantation. Histology of gaps 12 weeks post sham treatment showed mostly fibrotic scar tissue. On the contrary, EPC transplantation led to formation of dense and massive woven bone all throughout the defect. The results of this preclinical study open new therapeutic opportunities for the treatment of large scale bone injuries.     

Orderly osteochondral regeneration in a sheep model using a novel nano‐composite multilayered biomaterial

The objective of this article was to investigate the safety and regenerative potential of a newly developed biomimetic scaffold when applied to osteochondral defects in an animal model. A new multilayer gradient nano‐composite scaffold was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles. In the femoral condyles of 12 sheep, 24 osteochondral lesions were created. Animals were randomized into three treatment groups: scaffold alone, scaffold colonized in vitro with autologous chondrocytes and empty defects. Six months after surgery, the animals were sacrificed and the lesions were histologically evaluated. Histologic and gross evaluation of specimens showed good integration of the chondral surface in all groups except for the control group. Significantly better bone regeneration was observed both in the group receiving the scaffold alone and in the group with scaffold loaded with autologous chondrocytes. No difference in cartilage surface reconstruction and osteochondral defect filling was noted between cell‐seeded and cell‐free groups. In the control group, no bone or cartilage defect healing occurred, and the defects were filled with fibrous tissue. Quantitative macroscopic and histological score evaluations confirmed the qualitative trends observed. The results of the present study showed that this novel osteochondral scaffold is safe and easy to use, and may represent a suitable matrix to direct and coordinate the process of bone and hyaline‐like cartilage regeneration. The comparable regeneration process observed with or without autologous chondrocytes suggests that the main mode of action of the scaffold is based on the recruitment of local cells. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:116–124, 2010     

Intraoral application of vacuum-assisted closure in the treatment of an extended mandibular keratocyst

In extended cysts of the jaw bone particular demands are made in terms of wound closure, especially if an intraoral surgical approach is chosen. A tight closure is even more important if the bony defect has been filled with an alloplastic material or autologous cancellous bone. In our case a keratocyst of the left mandibular angle and ascending ramus was treated. After enucleation of the cyst and grafting with autologous cancellous bone the graft was lost following a wound breakdown. Subsequently a system was developed to apply intraoral V.A.C.-therapy. This led to a safe separation of the cystic defect and the oral cavity and a conditioning of the wound ground. A grafting with an alloplastic material was carried out successfully. With this method the length of treatment could be reduced by several months compared to a conventional therapy with an obturator.     

自体颅骨粉末移植和膜引导再生技术修复兔颅骨缺损的组织学研究

目的应用自体颅骨粉末移植和膜引导再生技术修复兔颅骨缺损模型,观察其组织学演变过程。方法选取50只新西兰大白兔,建立直径1 cm的颅骨全层缺损模型。移植自体骨粉修复兔颅骨缺损,并在移植的骨粉上放置可吸收生物膜,以纤维蛋白胶固定。术后2、4、6、8、12周取材进行组织学观察。结果术后2周,可观察到颅骨缺损区大量骨粉,炎性细胞、毛细血管和成纤维细胞由周围向内浸润,骨粉被吞噬吸收,周边小部分是新生骨,两者之间界限明显。术后4周,观察到骨粉吸收和新骨形成活跃区域向缺损中央内移较多,新生编织骨有所增粗,编织骨之间连接更为紧密,观察到的组织和细胞成分与术后2周时无明显变化。术后6周,基本观察不到未被吸收的骨粉,新生的编织骨变粗,联系更紧密。术后8周,完全观察不到骨粉,缺损中央部已形成单层新生骨,周边部形成的编织骨较为粗大,与正常骨紧密连接,形成初级骨髓腔。术后12周,缺损中央部形成双层新生骨,可见新生骨的改建和较为成熟的骨髓腔,腔内容物形态和成分与正常骨无区别。结论应用自体颅骨粉末移植和膜引导再生技术可以修复颅骨缺损,其组织学演变过程实质是引导性和诱导性骨再生的过程。     

Hyperbaric oxygen does not accelerate latent in vivo prostate cancer: implications for the treatment of radiation-induced haemorrhagic cystitis

OBJECTIVE: To assess the effects of hyperbaric oxygen (HBO2; often used to treat haemorrhagic cystitis, a known side-effect after radiation therapy for prostate cancer and with the potential to induce tumour angiogenesis and stimulate latent recurrence) on indolent in vivo prostate cancer in a murine model. MATERIALS AND METHODS: Human prostate LNCaP cells were injected into 60 severe combined-immunodeficient mice; of these 24 (40%) did not develop palpable tumours after 6 weeks. They were randomized to undergo 20 sessions of either HBO2 or normobaric air in standardized conditions, and observed for another 4 weeks before the histological assessment of any palpable tumours that developed. Analysis of developed LNCaP tumours included tumour volume, microvessel density, MIB-1, p53, p27 and racemase staining intensity. RESULTS: HBO2 was associated with less prostate tumour progression than normobaric air (P = 0.26). During HBO2 therapy, 10 mice remained free of palpable tumours, compared with seven controls (P = 0.30). On evaluation during the 4 weeks after therapy, six mice treated with HBO2 remained free of palpable tumours, vs eight of the controls (P = 0.17). There was tumour invasion and necrosis in a two of six and four of the HBO2 group during and after therapy, respectively, vs five and seven of the controls. Tumour microvessel density, proliferative index, differentiation and apoptosis markers were similar in both groups. CONCLUSIONS: HBO2 does not accelerate the growth of indolent prostate cancer in a murine model, suggesting that it does not increase the risk of residual prostate cancer reactivation when it is used to manage radiation-induced haemorrhagic cystitis in patients treated by pelvic radiotherapy for prostate cancer.     

Bridging the gap: Bone marrow aspiration concentrate reduces autologous bone grafting in osseous defects

Although autologous bone grafting represents an effective tool to induce osteogenic regeneration in local bone defects or pseudarthroses, it is associated with significant donor site morbidity and limited by the amount available for grafting. We investigate the potency of bone marrow aspiration concentrate (BMAC) to augment bone grafting and support bone healing. The functional and radiographic outcome of 39 patients with volumetric bone deficiencies treated with BMAC are presented and evaluated in a prospective clinical trial. A collagen sponge (Col) served as scaffold in 12 patients and a bovine hydroxyapatite (HA) was applied in the other 27 individuals. The minimal follow‐up was 6 months. Clinical and radiographic findings were completed by in vitro data. All patients showed new bone formation in radiographs during follow‐up. However, two patients underwent revision surgery due to a lack in bone healing. In contrast to the Col group, the postoperative bone formation appeared earlier in the HA group (HA group: 6.8 weeks vs. Col group 13.6 weeks). Complete bone healing was achieved in the HA group after 17.3 weeks compared to 22.4 weeks in the Col group. The average concentration factor of BMAC was 5.2 (SD 1.3). Flow cytometry confirmed the mesenchymal nature of the cells. Cells from BMAC created earlier and larger colonies of forming units fibroblasts (CFU‐F) compared to cells from bone marrow aspirate. BMAC combined with HA can reduce the time needed for healing of bone defects when compared to BMAC in combination with collagen sponge. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:173–180, 2011     

Heterotopic implantation of autologous bone marrow in rock pigeons (Columba livia): possible applications in avian bone grafting

Autologous bone marrow, alone or as a composite marrow graft, has received much attention in various species. To assess the potential osteogenicity of autologous, extramedullary bone marrow implants in an avian model, 24 adult pigeons (Columba livia) were given intramuscular implantations of autologous marrow aspirated from the medial tibiotarsus. Birds were euthanatized at 1, 4, 6, 8, 10, and 12 weeks after surgery to evaluate whether ectopic bone had formed at the implant sites. Primary evaluations by in situ radiography and postmortem histologic examinations showed no evidence of bone formation. Further evaluation with histologic scores and histomorphometry revealed a significantly increased rate of angiogenesis at the implant sites by the sixth and tenth week postimplantation (P < .05). No significant differences between the treatment and control sites were present at any other endpoints. Results of this study show that, although autologous bone marrow lacks heterotopic osteogenic potentials in this avian model, it could still function as a useful adjunct to routine bone grafting techniques because of its unique capabilities to promote early angiogenesis.     

Intramyocardial CD34+ cell transplantation combined with off-pump coronary artery bypass grafting

This report describes a new therapeutic approach for severe ischemic heart disease, intramyocardial transplantation of autologous bone marrow-derived CD34 + cells combined with off-pump coronary artery bypass grafting (CABG). CD34 is widely known as a cell surface antigen expressed on hematopoietic stem cells, and recent experimental studies have shown that CD34 + cells include endothelial progenitor cells. We used the Isolex 300i magnetic cell selection system to separate CD34 + cells from bone marrow cells. This report describes the first case treated with the combination of off-pump CABG and cell transplantation for therapeutic angiogenesis and myocardial regeneration. The transplantation of autologous bone marrow-derived CD34 + cells improved perfusion of the ungraftable ischemic area.     

Bone grafting of cryosurgically treated bone defects: experiments in goats

It is hypothesized that cryosurgically treated bone defects are inappropriate host sites for cancellous bone grafting. The influence of autologous cancellous bone grafting on the healing of cryosurgically treated gap defects of long bones was investigated. A unilateral in vivo experiment was done to study bone strength and graft incorporation in the goat. The lining of a cylindrical defect of the femoral diaphysis was treated with a closed liquid nitrogen cryoprobe in 62 goats. Thirty-one animals received an impacted, morselized, cancellous bone graft harvested from the sternum. The other 31 animals served as controls. At 0, 4, 7, 10, 13, 16, and 26 weeks animals were euthanized and the femurs were evaluated for torsional strength, computed tomography, and histologic assessment. Specimens with a bone graft showed no significant increase in torsional strength with time compared to the controls. In all goats euthanized at 10 weeks or later, the graft was resorbed. The amount of bone apposition at the site of the cryosurgical lesion and the time at which the defect was bridged were similar in both groups. Autologous cancellous bone grafting does not accelerate healing of cryosurgically treated, stable, diaphyseal defects in the goat.