Time-dependent sensory nerve ingrowth into a bone conduction chamber

We studied time-dependent ingrowth of sensory nerve fibers into a bone defect in a rat bone conduction chamber model. In 10 male Sprague Dawley rats, a titanium chamber was implanted bilaterally in the proximal tibiae, representing an experimental bone defect. To mimic a clinical situation, the chambers were filled with a fresh blood clot. After 1, 2, 4, 6 and 8 weeks, 2 rats were fixed in vivo at each time before removal of specimens, and histological and immunohistochemical analyses. We used antisera against protein gene product 9.5, neural growth-associated protein 43/B-50, calcitonin gene-related peptide, and substance P, to locate regenerating sensory nerve fibers in the chamber. During bone defect healing, hematoxylin/eosin sections showed that new bone grew in through the ingrowth openings in the chamber, gradually filling it and replacing the blood clot. At 1 and 2 weeks after implantation, no nerve fibers could be detected. At 4, 6 and 8 weeks, however, small numbers of nerve fibers were seen in 8 of 11 specimens. The nerve fibers were located mainly in the dense fibrous tissue in close proximity to the new bone, and in some cases within the new forming bone. In this chamber model, the periosteum is not in contact with the bone ingrowth openings, and all ingrowing nerve fibers thus originated from the cortical bone, endosteum or bone marrow. We speculated that these late ingrowing sensory nerve fibers may actively participate in bone repair.     

Time-dependent sensory nerve ingrowth into a bone conduction chamber

We studied time-dependent ingrowth of sensory nerve fibers into a bone defect in a rat bone conduction chamber model. In 10 male Sprague Dawley rats, a titanium chamber was implanted bilaterally in the proximal tibiae, representing an experimental bone defect. To mimic a clinical situation, the chambers were filled with a fresh blood clot. After 1, 2, 4, 6 and 8 weeks, 2 rats were fixed in vivo at each time before removal of specimens, and histological and immunohistochemical analyses. We used antisera against protein gene product 9.5, neural growth-associated protein 43/B-50, calcitonin gene-related peptide, and substance P, to locate regenerating sensory nerve fibers in the chamber. During bone defect healing, hematoxylin/eosin sections showed that new bone grew in through the ingrowth openings in the chamber, gradually filling it and replacing the blood clot. At 1 and 2 weeks after implantation, no nerve fibers could be detected. At 4, 6 and 8 weeks, however, small numbers of nerve fibers were seen in 8 of 11 specimens. The nerve fibers were located mainly in the dense fibrous tissue in close proximity to the new bone, and in some cases within the new forming bone. In this chamber model, the periosteum is not in contact with the bone ingrowth openings, and all ingrowing nerve fibers thus originated from the cortical bone, endosteum or bone marrow. We speculated that these late ingrowing sensory nerve fibers may actively participate in bone repair.     

Time-dependent sensory nerve ingrowth into a bone conduction chamber

We studied time-dependent ingrowth of sensory nerve fibers into a bone defect in a rat bone conduction chamber model. In 10 male Sprague Dawley rats, a titanium chamber was implanted bilaterally in the proximal tibiae, representing an experimental bone defect. To mimic a clinical situation, the chambers were filled with a fresh blood clot After 1, 2, 4, 6 and 8 weeks, 2 rats were fixed in vivo at each time before removal of specimens, and histological and immunohistochemical analyses. We used antisera against protein gene product 9.5, neural growth-associated protein 43/B-50, calcitonin gene-related peptide, and substance P, to locate regenerating sensory nerve fibers in the chamber. During bone defect healing, hematoxylin/eosin sections showed that new bone grew in through the ingrowth openings in the chamber, gradually filling it and replacing the blood clot. At 1 and 2 weeks after implantation, no nerve fibers could be detected. At 4, 6 and 8 weeks, however, small numbers of nerve fibers were seen in 8 of 11 specimens. The nerve fibers were located mainly in the dense fibrous tissue in close proximity to the new bone, and in some cases within the new forming bone. In this chamber model, the periosteum is not in contact with the bone ingrowth openings, and all ingrowing nerve fibers thus originated from the cortical bone, endosteum or bone marrow. We speculated that these late ingrowing sensory nerve fibers may actively participate in bone repair.     

No effect of growth hormone on bone graft incorporation: Titanium chamber study in the normal rat

A recent series of publications reported greatly improved mechanical properties and increased callus size during the late stages of fracture healing in normal (not hypophysectomized) rats after twice daily injections of growth hormone (GH). We tested whether GH could enhance the incorporation of bone allografts in a new experimental model where we have demonstrated an increase in bone allograft incorporation by local application of basic fibroblast growth factor (bFGF)- Cylinders of defatted allogeneic cancellous bone were placed as grafts in titanium Bone Conduction Chambers in the tibiae of female rats. Only one end of this chamber is open for tissue ingrowth. This permits us to measure the distance into the graft that new bone penetrates after entering the chamber. We injected 10 rats with 1.5 IU per rat of subcutaneous human recombinant GH twice daily for 6 weeks and another 10 rats with similar doses of sterile normal saline. GH caused a constant increase in the rate of weight gain and in the serum concentration of Insulin-like Growth Factor 1 (IGF 1). Tibiae became longer and the ash weight of the second tail vertebra was increased. We also noted an increased joint cartilage thickness. There was no difference in the amount of new bone that had penetrated and replaced parts of the graft in GH-treated or control rats and this was also the case with TcMDP activity of bone samples from both groups. New bone forms in the grafts by membranous (metaplastic) ossification. It appears that the effects of excessive GH stimulation on endochondral and membranous ossification in this model are markedly different.     

No effect of ketoprofen and meloxicam on bone graft ingrowth: A bone chamber study in goats

Background and purpose?There is increasing awareness that non‐steroidal anti‐inflammatory drugs (NSAIDs), and especially the cyclooxygenase‐2 (COX‐2) selective ones, may retard bone healing. We have used NSAIDs (indomethacin for at least 7 days) to prevent heterotopic ossification after acetabular reconstructions using impacted bone grafts. The long‐term clinical results have been satisfying, making it difficult to believe that there is an important negative effect of NSAIDs on graft incorporation. We studied the effect of two different NSAIDs on bone and tissue ingrowth in a bone chamber model in goats, using autograft, rinsed allograft, and allograft that had been rinsed and subsequently irradiated.

Methods?9 goats received no NSAIDs, 9 received ketoprofen, and 9 received meloxicam—all for 6 weeks. In each goat 6 bone chambers were implanted: 2 filled with autograft, 2 with rinsed allograft, and 2 with allograft that had been rinsed and irradiated. The amount of bone ingrowth and total tissue ingrowth was compared between the groups.

Results?There were no statistically significant differences in bone ingrowth between the different groups. Also, no differences in bone ingrowth were found with respect to the type of graft used. Furthermore, there was no statistically significant difference in the total amount of ingrowth of fibrous tissue between the treatment groups.

Interpretation?No differences in bone ingrowth in titanium bone chambers could be detected with both ketoprofen and meloxicam compared to untreated control animals. This confirms our hypothesis that the effect of NSAIDs on the incorporation and ingrowth of bone graft is limited.     

Banked bone grafting for bone defect repair--clinical evaluation of bone union and graft incorporation

One hundred and twenty-four banked bone grafts performed during the past 15 years were studied in respect to union and graft incorporation processes using X-ray, bone scintigraphy and histology. Radiological study of the chip graft showed an absence of cavity contours, and homogenization of the grafted area, followed by development of the trabecular structure. In the block graft, initial union was shown at the junctional area followed by the appearance of mottled shadows throughout the entire graft and finally differentiation of bone marrow and cortex. Bone scintigraphy showed an initial increase in RI uptake at the junction and then a gradual increase in the entire graft. Histological study showed that bone apposition on the trabeculae of the graft starts in the junction and later extends to other areas. The replacement of cancellous bone is more rapid than that of cortical bone. The porous surface seems to promote bone union and incorporation when large block grafts of cortical bone are used.     

Basic fibroblast growth factor infused at different times during bone graft incorporation Titanium chamber study in rats

We investigated the effect of applying basic fibroblast growth factor (bFGF) to a bone graft during different stages of incorporation in an infusion bone chamber model. Bone chambers were implanted bilaterally into rat tibiae. Both chambers were connected to an implanted osmotic minipump. Ingrowing bone could enter the cylindrical interior of the chamber only at one end. The distance which ingrowing bone had reached into the bone graft was then measured on histological slides. Specimens were also analyzed by ^99mTc-MDP scintimetry. The infusion of buffer during 2 weeks from implantation had no effects on tissue ingrowth distance or quality. bFGF was infused during 2 weeks from implantation in a dose of either 1.2 or 12 ng/day. Bone ingrowth was measured 6 weeks after implantation. The higher dose had a more marked effect and was used for studying the effect of application at different times.The maximum stimulation of bFGF as measured at 6 weeks postimplantation was found after infusion during the first postimplantation week. Infusion during the third and fourth weeks had no effect at 6 weeks, but tended to increase the bone ingrowth distance at 8 weeks postimplantation. These findings suggest that bFGF infusion increases bone ingrowth into bone grafts when infused at both an early and a later stage, but the effect can be measured only several weeks later.     

Sensory nerve damage during surgery on the hallux.

Division of the medial branch of the superficial peroneal nerve during surgery on the hallux can lead to unpleasant and troublesome symptoms, including neuroma formation. This study aims to show the incidence and consequences of damage to this nerve and to describe an easily applied solution. A total of 75 feet (51 randomly selected patients) was examined, with a mean follow-up of 4 years. Evidence of nerve damage was seen in 45% on clinical examination but, interestingly, only 29% were aware of their symptoms when questioned beforehand. In 3% the symptoms were severe and disabling. In view of this unexpectedly high incidence, ten cadaveric feet were dissected with a reliable surface marking being described to avoid the nerve during surgery.     

Progression of human bone ingrowth into porous-coated implants: Rate of bone ingrowth in humans

We report the measured progression of human cancellous bone ingrowth into load-bearing porous-coated titanium implants over 5 time periods (0,3,6, 9, and 12 months). There was a statistically significant progression of bone ingrowth into the implants over a 9-month period, but the 9- and 12-month data were not different. Investigators are advised to analyze time “0” implants in order to distinguish mechanical impaction of bone from the biological process of bone ingrowth.     

Inside-out vein graft and inside-out artery graft in rat sciatic nerve repair

Although veins and arteries present similar wall structures, there are differences which may be relevant in peripheral nerve reconstruction. Inside-out vein grafts (IOVG) have been satisfactorily used to repair both motor and sensitive nerves. However, the inside-out artery graft (IOAG) is a new technique and not fully investigated. Our study presents comparative morphological data on nerve regeneration achieved with IOVG and IOAG in the repair of Wistar rat sciatic nerves. Jugular veins and aorta arteries were harvested from donor animals and used "inside-out" to bridge a 10-mm gap. Animals were sacrificed at 10 weeks to evaluate nerve regeneration. Both techniques presented great variability in nervous tissue, though some animals showed satisfactory results. Different intensities of scarring processes might have interfered with nerve regeneration. Although IOVG and IOAG techniques showed similar morphometric results, in general, IOVG presented a closer-to-normal nerve organization than IOAG.     

Injury to the lateral femoral cutaneous nerve during harvest of iliac bone graft,with reference to the size of the graft

In patients who underwent autogenous iliac bone grafting we studied prospectively injury to the lateral femoral cutaneous nerve (LFCN) in relation to the size (length, depth, width) of the graft. We also examined the neurological deficit, by questioning them about numbness and/or pain in the lateral thigh. The risk of injury was significantly higher in those in whom the depth of the graft was more than 30 mm. With regard to the length of the graft the incidence of nerve injury was 20% when the graft was 45 mm long or more, 16% when it was between 30 mm and 45 mm long, and 8% when it was less than 30 mm long. We should inform patients of the possibility of such injury, and take size into consideration when harvesting grafts from the ilium.     

Combination of growth factors inhibits bone ingrowth in the bone harvest chamber

Previous studies using bone harvest chambers have shown that bone morphogenetic protein-2 inhibits bone ingrowth. The authors hypothesized that the combination of bone morphogenetic protein-2 and a potent angiogenic factor, basic fibroblast growth factor, would result in increased bone formation in this model. Five New Zealand White rabbits were surgically implanted with bone harvest chambers in the proximal metaphyseal region of both tibias. The right leg of each rabbit was implanted with a bovine collagen sponge that was impregnated with recombinant human bone morphogenetic protein-2, basic fibroblast growth factor, or a combination of these factors. The left leg chamber was implanted with the collagen sponge with no growth factors as a control. The bone that grew into the chambers was harvested after 2 weeks, and histomorphologic analysis was performed to determine the amount of tissue and bone ingrowth. The tissue chambers were left empty for 2 weeks between test implants, and this tissue also was harvested, analyzed, and compared with the other samples. The results showed decreased bone formation for the bone morphogenetic protein-2, basic fibroblast growth factor, and combination of bone morphogenetic protein-2 and basic fibroblast growth factor treated groups when compared with the control and empty groups. The combination of bone morphogenetic protein-2 and basic fibroblast growth factor showed inhibition of bone formation that was greater than either growth factor individually. The reason for the inhibition of bone formation with the combination of factors is unknown.     

Effect of zoledronic acid on incorporation of a bioceramic bone graft substitute

Many osteoporotic fracture patients are candidates for concurrent treatment with bisphosphonates and bioceramic bone graft substitutes. Osteopromotive silica-based bioactive glasses are known to induce accelerated local bone turnover and adjunct antiresorptive agents, such as zoledronic acid, may affect the process. The current study examined the effect of adjunct zoledronic acid therapy on bioactive glass incorporation. In Harlan Sprague-Dawley rats (n = 80), a standardized region of the proximal tibia was subjected to ablation of local bone marrow and filled with bioactive glass (BG) microspheres. Experimental animals received zoledronic acid (1.5 mug/kg, s.c., once a week, started 1 week before surgery) or doxycycline (a metalloproteinase inhibitor) (33 mg/kg, daily gavage) as a control agent. BG incorporation and geometric bone properties were followed by sequential pQCT imaging. The final outcome at 8 weeks was analyzed by digital radiography, histomorphometry, BEI-SEM, EDXA and muCT. The mRNA levels of markers for bone resorption (cathepsin K, TRACP, MMP-9, MMP-13) and synthesis (type I, II, III collagens, osteocalcin, osteonectin, osteopontin) were measured for determination of local bone turnover. Bones filled with BG microspheres produced 2.5-fold more intramedullary new bone than controls with bone marrow ablation only, but the BG filling delayed the recovery of pQCT strength strain index (SSI) of the bones. Adjunct therapy with zoledronic acid enhanced new bone formation on BG microspheres and particularly improved the SSI values of the BG-filled bones (P < 0.05). The zoledronic acid therapy alone (without BG filling) produced the highest amount of intramedullary new bone (6-fold more than in unfilled controls, P < 0.001) but did not show a similar benefit in SSI. The analyses of mRNA expression confirmed high local bone turnover in all bones with BG filling. At the 9th week of zoledronic acid treatment, bones with and without BG filling showed increased mRNA levels of bone resorption markers and decreased mRNA levels of markers for synthesis, indicating that a corrective resorption process was already in progress in response to massive accumulation of medullary new bone at earlier stages of the therapy. Adjunct antiresorptive therapy seems to be beneficial for incorporation of bioactive glass microspheres and does not block local natural remodeling processes. In the current model, the therapy even resulted in favorable remodeling of the tubular bone structure.     

阿仑膦酸钠对人工关节假体周围骨长入的影响

目的观察阿仑膦酸钠对人工关节假体周围骨长入的影响。方法SD雄性大鼠16只,双侧胫骨上端经膝关节植入定制钛合金假体,随机分成对照组和实验组,对照组术后每日空腹生理盐水灌胃;实验组术后每日空腹阿仑膦酸钠灌胃,剂量0.1 mg/(kg.d),持续6周。术后12周处死取材,进行组织学观察及组织形态计量学测定。结果组织学观察发现,对照组假体周围由新生骨、类骨质和纤维界膜构成。纤维界膜较厚,与新生骨或类骨质间界限清晰。实验组假体周围纤维界膜薄且稀少,新生骨与假体界面多为直接接触,有些部位新生骨与假体界面完全整合。组织形态计量学测定发现,对照组假体周围界膜的厚度和面积均明显大于实验组,差异有显著性(P<0.05)。结论阿仑膦酸钠经胃肠给药可能对钛合金人工关节假体周围骨长入有一定的促进作用。     

Antibiotic resistance of crystalline bacterial ingrowth in a corneal graft

Four recent reports have described the clinical appearance of fine needle-like opacities in the corneal stroma of six patients. In five of these patients these developed in a corneal graft. Histologically, all the corneal buttons had bacterial ingrowth between the stromal lamellae, with a striking lack of inflammatory response. We report a patient in whom this process occurred following penetrating keratoplasty. Intensive topical antibiotic treatment failed, and she underwent a second, successful, penetrating keratoplasty. Postoperatively, this patient has maintained good vision with no recurrence for over three years. Histologic and ultrastructural study of the corneal button revealed viable and nonviable gram-positive cocci with a marked paucity of inflammatory infiltrate.     

Microsurgical nerve graft repair of the ablated cavernosal nerves in the rat.

Erectile dysfunction is a significant complication of radical pelvic surgery in men. Using the rat as an experimental model, we investigated the feasibility of repairing surgically ablated cavernosal nerves. Known fertile male Sprague-Dawley rats were randomly divided into three surgical groups of 30 animals (60 study nerves) per group consisting of nerve ablation, immediate nerve reconstruction, and control groups. The nerve ablation group had 5-mm sections of the cavernosal nerve excised bilaterally. The nerve graft group had 5-mm sections of the cavernosal nerve excised bilaterally, followed by immediate microsurgical reconstruction with an autologous interposition nerve graft utilizing the ipsilateral genitofemoral nerve bilaterally. The anastomoses were performed with 10-O nylon sutures at 16 to 25x magnification. The control group underwent sham operations with the cavernosal nerves being exposed only. Erectile function was evaluated at 1, 2, 4, and 6 months postoperatively. Return of erectile function was defined as tumescence of the corporal bodies with application of direct electrical stimulation (3 V of 5 msec pulses at 20 Hertz) to the proximal cavernosal nerves. The 4- and 6-month electrical stimulation studies resulted in tumescence from 65 and 75% of the grafted nerves, which represented a significant difference compared to the ablated group 11 and 5%, respectively (P less than 0.001 at 4 and 6 months). Behavioral copulatory studies, performed prior to electrical stimulation testing, corresponded closely with the results of electrically induced tumescence. We conclude that in this experimental model immediate nerve graft repair appears to be a successful method of salvaging erectile function when the cavernosal nerves have been divided.