Free revascularised periosteum transplantation: an experimental study

Vascularized periosteal transfer from the medial femoral condyle: is it compulsory to include the cortical bone?

BACKGROUND

The corticoperiosteal flap from the medial femoral condyle has become the workhorse in the management of recalcitrant nonunions with vascularized periosteum. Inclusion of the outer condylar cortex has been advocated to avoid damaging the osteogenic capacity of the periosteum and is at present an ordinary technical step in the procedure.

PATIENTS

A clinical prospective study was undertaken to evaluate the effectiveness of periosteal-only microvascular transfers from the medial femoral condyle associated with bone grafts in the treatment of recalcitrant nonunions. A group of 8 patients with periosteal-only flaps (study group) is compared with a corticoperiosteal control group (13 patients). A statistical analysis is made of the results.

RESULTS

We had 100% union rate in both the study and control groups. Evaluation of early signs of bone healing by two independent evaluators did not found differences between the groups (4.5 months in the study and 4.9 months in the control group).

CONCLUSIONS

Although not statistically significant because of the small sample size, our study might support the idea that both periosteal and corticoperiosteal flaps from the medial femoral condyle are effective, when associated with a bone graft, in the treatment of recalcitrant nonunions with small gaps. A further analysis of the results suggests, albeit no statistical significant, that structural and nonstructural bone grafts are both effective when associated with a vascularized periosteal or corticoperiosteal transfer from the medial femoral condyle.

[Vascularized periosteum and bone regeneration]

The osteogenic potential of periosteum is widely recognized. During development, it plays a prominent role in the radial growth of long bones. Similarly, it has a key role in the consolidation of fractures. The physiological function of periosteum in the healthy, mature skeleton remains relatively subtle; however, its detachment from the bone surface reactivates its potential for fibrogenic and osteochondrogenic regeneration. This discreet anatomical structure is actually a reservoir of mesenchymal progenitor cells capable of proliferating and differentiating, by reinitializing cellular and molecular cascades of embryogenesis in mesenchymal tissues. However, given the hitherto limited knowledge of the quantitative potential of periosteum and of the pathways regulating tissue differentiation during regeneration, human applications have remained anecdotal. The findings of several in vivo and in vitro experiments indicate that the maintenance of the periosteum's vascularization stimulates its quantitative potential. The structural organization of the regenerated material in vivo is governed by locoregional biological and mechanical regulatory mechanisms that serve to make it capable of performing its new functions. The increasing awareness of periosteum's potential is stimulating active research in the fields of cellular biology and tissue engineering. The demonstration of its regenerative potential in animals gives reason to believe that strips of vascularized periosteum could become part of the developing armamentarium of regenerative medicine.

Evaluation of osteogenic and chondrogenic activities of prefabricated periallografts

Reconstruction of cartilage and bone defects has always been a challenging problem for the surgeon. Basic elements that are responsible for the repair process of these tissues are periost and perichondrium. Although several methods for the use of periost and perichondrium are proposed in the literature, the osteogenic and chondrogenic capacities of these tissues were shown to be the most important factor for a successful outcome. Bone and cartilage formation in acellular dermal matrix (ADM) prefabricated with periost and perichondrium was studied in 20 New Zealand rabbits. Morphologic and histologic evaluation and comparison of the newly formed tissues were evaluated. Four rabbits were excluded from the study because of infection, and specimens were obtained at 4, 6, 8, and 12 weeks after the study began from the remaining 16 rabbits. A gradual increase in bone and cartilage tissue formation through the 4th to 12th weeks was documented by reason of perichondrium and periost activation infiltrating into acellular dermal allografts. In view of the data obtained, it was concluded that periost or perichondrium prefabricated over ADM may be an alternative technique of cartilage and bone formation that may provide adequate tissue with elastic and osteo- and chondroconductive properties for the reconstruction of challenging defects.

Guided Bone Regeneration at the Donor Site of Iliac Bone Grafts for Future Use as Autogenous Grafts

BACKGROUND

Autogenous bone grafting is considered the standard in management of bony defects but has some disadvantages, including limited source of graft material, especially in children. This study represents an attempt to regenerate bone at the donor site of iliac bone grafts using the guided bone regeneration principle for future use in multistage bone reconstruction by grafting.

METHODS

Critical size defects were created in 24 iliac bones of 12 skeletally mature New Zealand White rabbits. Defects in group 1 (n = 12) were covered with inverted U-shaped resorbable mesh (space maintainer) and polytetrafluoroethylene membranes underneath the periosteum. In group 2 (n = 6), inverted U-shaped resorbable mesh was used alone (positive control). In group 3 (n = 6), neither resorbable mesh nor polytetrafluoroethylene membranes were used (negative control). An unpaired t test was used for comparison between each two groups.

RESULTS

Plain radiographs and contact microradiographic studies showed that bone regeneration was significantly higher in group 1 and group 2 than in group 3 (p < 0.001). There was no significant difference between group 1 and group 2 regarding density.

CONCLUSIONS

The periosteum acted as an ideal membrane for guided bone regeneration so that the polytetrafluoroethylene membranes could be used only to compensate for the deficient periosteum. Space maintenance was essential for bone regeneration.

Osteogenic Capacities of Periost Grafts, Periost Flaps and Prefabricated Periosteal Flaps: Experimental Study

Reconstruction of the bone defects due to various causes is still one of the challenging problems in plastic and reconstructive surgery. Periosteum is accepted to be the essential source for the repair of the bone tissue, which constitutes the basis of the support and the mobility functions of the surrounding tissues. Periosteal grafts and flaps have been used for various purposes by numerous techniques. The osteogenic activity of the periosteal tissues has a great importance regarding the purposes of reconstruction. In this experimental study, 20 New Zealand rabbits were used for the evaluation and the comparison of the osteogenic activities of periosteal grafts, periosteal flaps and prefabricated periosteal flaps. Morphological, histopathological and scinthigraphical observations were carried out for the assessment and the comparison of the groups after a follow-up of 12 weeks. Two of the animals were left out as a result of infection. The results showed that periosteal flaps had a much faster and more stable reconstructive capacity of osteogenesis, whereas prefabricated periosteal flaps had an osteogenic capacity of a lower degree and periosteal grafts apparently less than the former groups. We believe that this study confirms the reconstructive capacity of prefabricated periosteal flaps as an alternative to periosteal flaps for the repair of osseous tissues as well as indicating the osteogenic capacity of the periosteal grafts, though in a lesser degree.

Repair of cartilage defects with periosteal grafts

Alternative sources for repair of cartilage defects are limited and donor sites are associated with morbidity. It is known that cartilage development from periosteal grafts is possible. Various factors have been found positively to affect this process in experimental settings. However, all of these studies were limited to joint cartilage. We conducted an experimental study in rabbits for the investigation of the elastic cartilage regeneration from perichondrial and periosteal grafts together with the effects of hyaluronan on this process. 1 x 1 cm(2) cartilage defects were created on the elastic ear cartilage of rabbits. Four experimental groups with 18 ears in each group were created: Group 1 (repair with perichondrium graft), group 2 (repair with periosteum graft), group 3 (repair with periosteum graft+hyaluronan), group 4 (defect-only control group). Macroscopic and microscopic evaluations were done on the 4th, 8th and 12th weeks. Cellular morphology of the regenerated cartilage and its integration and similarity with adjacent cartilage were evaluated. Cartilage regeneration groups 1, 2 and 3 were found to be statistically different from the control group. There was not a significant difference between groups 1 and 2 or 2 and 3. There is no significant difference between perichondrial and periosteal grafts in cartilage regeneration, and hyaluronan has no beneficial effect on this process.

Comparing the Osteogenic Capacities of Bone Substitutes: Hydroxyapatite, High-Density Porous Polyethylene, and Bone Collagen: A Biochemical and Histological Analysis

Several inorganic materials have been shown previously to hold some osteogenic capacity. The purpose of this study is to compare the bone-forming abilities of hydroxyapatite ceramic, high-density porous polyethylene, and bone collagen within the periosteal island flap of rabbit tibia using histological and biochemical analysis. With this goal, four discrete experimental groups were formed, each comprising 22 New Zealand male rabbits. A sac was created on each rabbit tibial periosteum flap in each of the groups, and each of the previously mentioned materials was placed within this sac separately. One of these groups was thought as a control group without any material being placed inside the periosteal sac. Biopsies were taken at weeks 1, 2, 4, and 8 for biochemical analysis and at weeks 2 and 8 for histological evaluation. Neo-osteogenesis was evaluated quantitatively by determination of alkaline phosphatase and osteocalcin levels biochemically as well as by the percentage of new bone formation inside the periosteal sac histologically. Results show statistically that the osteogenic effect of high-density porous polyethylene is greater than that of the other materials used in this study (P < 0.05).

Heterotopic neo-osteogenesis from vascularized periosteum and bone grafts

BACKGROUND

Periosteum is an osteogenic, flexible tissue. This study investigated the osteogenic potential of vascularized periosteal flaps in heterotopic conditions and compared it to the neo-osteogenesis from vascularized periosteal flaps combined with bone grafts with different properties (autologous and xenograft).

METHODS

Vascularized periosteal flaps from the hindlimbs of 48 rabbits formed cylindrical pouches that were buried in muscles. The pouches were filled with autologous bone grafts (P/A group, n = 16), xenograft (P/X group, n = 16), or left empty (P/E group, n = 16). Specimens were harvested between 1 and 4 months and underwent radiographic, histologic, and histomorphometric evaluation.

RESULTS

The total surface area was larger in the groups combined with bone grafts. Osseous apposition did not differ significantly in the P/A and P/X groups (p > 0.05). The central cavity contained hematopoietic cells (P/A), xenograft (P/X), or was absent (P/E).

CONCLUSION

Vascularized periosteal flaps presented strong osteogenic capacity in heterotopic conditions. Combination with bone grafts resulted in larger specimens. The quality of neo-osteogenesis was not influenced by the different properties of combined bone grafts.

Healing patterns in calvarial bone defects following guided bone regeneration in rats. A micro-CT scan analysis

OBJECTIVE

The objective of this study was to evaluate healing patterns of critical-size calvarial bone defects treated according to principles of guided bone regeneration using micro-CT scan analysis. Specifically, the contribution of bone, periosteum and dura mater to the amount and mineralization of newly formed bone was evaluated.

MATERIAL AND METHODS

Surgically induced, critical-size calvarial bone defects in 48 adult male Wistar rats received the following: an occlusive expanded polytetrafluoroethylene (ePTFE) membrane at the exo- and endocranial aspect (OO; n = 12); an occlusive membrane at the exocranial and a perforated membrane at the endocranial aspect (OP; n = 12); a perforated membrane at the exocranial and an occlusive membrane at the endocranial aspect (PO; n = 12); and a perforated membrane at the exo- and endocranial aspect (PP; n = 12). The animals were euthanized at 4 weeks for quantitative analysis of bone volume fraction and mineralization in the region of interest (ROI) as well as in the external, middle and central area of the defect using micro-CT.

RESULTS

Bone volume fraction ranged from 31.4% (OP) to 24.5% (PP). No differences were found among the groups. Bone volume fraction and mineralization in the middle area were significantly greater in group OP than in group PP, and in the central area in group OO and PO than in group PP.

CONCLUSIONS

The results of this study suggest that use of occlusive ePTFE membranes enhances bone formation and maturation in the calvarial skeleton. When occlusion of endo- and exocranial tissues was compromised by membrane perforation, impaired bone formation and mineralization were observed.

The role of beta-tricalcium phosphate in vascularized periosteum

To investigate the osteogenic capacity of vascularized periosteum in bore grafting, we prepared experimental groups by wrapping beta-tricalcium phosphate (beta-TCP) with vascularized periosteum of the femur of 12-week-old Japanese white rabbits, and evaluated osteogenesis histologically and biochemically. Bone formation was observed in the group with vascularized periosteum and in the group with bone marrow fluid added to the vascularized periosteum. In particular, woven bone was observed in the group that had added bone marrow. Osteogenesis appeared earlier in the group with bone marrow fluid added to the vascularized periosteum, but histologically, there was no significant difference between this group and the group with vascularized periosteum without bone marrow fluid added at week 24 after the operation. In the group with non-vascularized periosteum, slight osteogenesis was found at week 6 after the operation, but in the control group, with beta-TCP implanted in soft tissue, osteogenesis did not occur at all. Alkaline phosphatase (ALP) activity reached a peak at week 2 after the operation in the group with vascularized periosteum, but only half the peak value was then maintained until week 8. In the group with bone marrow fluid added to the vascularized periosteum, similar values were found from immediately after the operation until week 8. ALP activity did not show any significant difference between these two groups at week 8 postoperatively. In the group with beta-TCP implanted in the soft tissue, ALP activity was low at all times measured. These results suggested that the periosteum had osteoinduction capacity and beta-TCP had osteoconduction capacity; that better osteogenesis occurred with vascularized periosteum; and that bone marrow fluid was involved in the promotion of osteoblastic activity, but not in calcification.

Experimental use of fibrin glue to induce site-directed osteogenesis from cultured periosteal cells

The purpose of this study was to determine whether a combination of fibrin glue and cultured periosteal cells will result in new bone formation at heterotopic sites in nude mice. Growing cells and developing matrices surrounding periosteal explants from the diaphyses of radii of newborn calves were minced and mixed with fibrin glue in a syringe. The cell/matrix-fibrin glue admixture was then injected into the subcutaneous space on the dorsum of athymic nude mice. After 12 weeks of implantation, gross morphology and histologic investigations showed newly formed bone structures in all cell/matrix-fibrin glue admixtures, but none in fibrin glue injected alone and used as control samples. Osteopontin, a protein important in bone development, was identified by a Western blot assay of the cell/matrix-fibrin glue composite. This study supports the feasibility of initiating site-directed formation of bone structures at heterotopic tissue sites by means of injection of cultured periosteal cells and matrix in a fibrin glue carrier.

Formation of phalanges and small joints by tissue-engineering

BACKGROUND

This report describes the formation of small phalanges and whole joints from three types of bovine-cell sources transplanted onto biodegradable polymer matrices. The resulting structures had the shape and composition of human phalanges with joints.

METHODS

Fresh bovine periosteum was wrapped around a copolymer of polyglycolic and poly-L-lactic acid. Separate sheets of polyglycolic acid polymer were then seeded with chondrocytes and tenocytes isolated from the shoulders of freshly killed calves. The gross form of a composite tissue structure was constituted in vitro by assembling the parts and suturing them to create models of a distal phalanx, a middle phalanx, and a distal interphalangeal joint.

RESULTS

Subcutaneous implantation of the sutured composite tissues into athymic mice resulted in the formation, after twenty weeks, of new tissue with the shape and dimensions of human phalanges with joints. Histological examination revealed mature articular cartilage and subchondral bone with a tenocapsule that had a structure similar to that of human phalanges and joints. There was continuous cell differentiation at the ectopic site even after extended periods.

CONCLUSIONS

These findings suggest that the formation of phalanges and small joints is possible with the selective placement of periosteum, chondrocytes, and tenocytes into a biodegradable synthetic polymer scaffold.

Osteogenic ability of free periosteal autografts in tibial fractures with severe soft tissue damage: an experimental study

OBJECTIVE

The present study was undertaken to assess whether free nonvascularized autologous periosteum transplants enhance bone healing in a rabbit fracture model designed to resemble a tibial fracture with severe soft tissue damage.

DESIGN

Transplantation of free autologous periosteal grafts on the anteromedial site of the tibia (experimental group) was compared with nontransplantation on the contralateral tibia (control group). We produced a standardized transverse osteotomy of both tibial diaphyses in white male adult New Zealand rabbits. The endomedullary cavity was reamed and nailed, and then a one-centimeter segment of periosteum was excised from either side of the osteotomy. To prevent periosteal and extraosseous ingrowth at the osteotomy site, a silastic sheet was wrapped around two-thirds of the circumference of the tibia. In the first group, on the silastic-free bone window, we then spanned the osteotomy with a free, nonvascularized, longitudinally oriented autologous periosteum and sewed it to the adjacent periosteum both proximally and distally. In the second group, the periosteum was placed transversely, leaving a gap between it and the adjacent periosteum proximally and distally. Revascularization of the graft was determined with the colored microsphere technique.

MAIN OUTCOME MEASUREMENTS

Histomorphometric analysis of the periosteal callus was done on a transparent grid superimposed on enlarged photographs of the histologic sections.

RESULTS

Free, nonvascularized, longitudinally placed autologous periosteum in contact with intact periosteum produced significantly more periosteal callus than was seen in the control group, in which no periosteal graft was used. However, when transversely placed periosteal grafts were set in the silastic-free bone window and there was no contact with surrounding remnants of intact periosteum, no significant difference in callus production was noted when compared with the control. Revascularization of these grafts was seen within one week after transplantation. Bone healing occurred mainly through endochondral ossification.

CONCLUSION

Our data suggest that orthotopically placed autologous nonvascularized periosteum retains its osteogenic potential in a poorly vascularized environment such as a tibial fracture with severe soft tissue damage. The effect is enhanced if the graft is in contact with intact periosteum. Histologically, callus formation after periosteal grafting resembles endochondral and intramembranous ossification.

Osteogenic potential of cultured periosteal cells in a distracted bone gap in rabbits

Osteogenesis of cultured periosteal cells was investigated in a bone-defective gap that was created artificially by distraction in the tibia of 12-week-old rabbits. A 10-mm circumferential length of periosteum was stripped from each stump of the osteotomized tibia, and the tibia was distracted rapidly (2 mm/day), resulting in disturbance of callus formation. Periosteal-derived cells, which were isolated from the contralateral tibia, were introduced into cell culture, subcultured twice to a population of 5 x 10(7) cells, and then injected into the defective bone gap when distraction was complete. Following inoculation of the cultured cells, significant new bone formation in the bone gap was observed. The control group which did not undergo cell transplantation showed only slight new callus formation which is supposed to be formed by osteogenic cells from the bone marrow. The bone mineral content of newly formed bone between the distracted tibia was analyzed quantitatively on radiographs. Histologically, the transplanted cells initially formed a mass at the injected site and then gradually differentiated into bone tissue from the peripheral region. Bromodeoxyuridine immunohistochemical stain was utilized to investigate the localization of the transplanted cells. The present study confirms that the orthotopically implanted periosteum-derived cells facilitate osteogenesis in a bone defect created using distraction in rabbits.

Histologic and biochemical analysis of osteogenic capacity of vascularized periosteum

We analyzed the osteogenic capacity of the vascularized periosteum histologically and biochemically using a new experimental model of the vascularized tibial periosteum-hydroxyapatite composite in rats. Bone formation was observed not only on the surface but also in the pores of the hydroxyapatite at 4 weeks. The alkaline phosphatase activity increased to a peak at 2 weeks, with half this activity maintained until 8 weeks. The bone-specific bone gla protein content increased constantly as time passed. On the other hand, in the vascularized fascia-hydroxyapatite composite group (control group), no bone formation was observed histologically, alkaline phospatase activity was low, and bone gla protein content was very low. These results indicate that (1) the vascularized periosteum has the most significant osteogenic capaacity at 2 weeks, with a constant level of the activity maintained thereafter, (2) it forms new bone soon after operation, and (3) the amount of bone increases as time passes.

Guided bone regeneration in calvarial bone defects using polytetrafluoroethylene membranes

Guided bone regeneration is defined as controlled stimulation of new bone formation in a bony defect, either by osteogenesis, osteoinduction, or osteoconduction, re-establishing both structural and functional characteristics. Bony defects may be found as a result of congenital anomalies, trauma, neoplasms, or infectious conditions. Such conditions are often associated with severe functional and esthetic problems. Corrective treatment is often complicated by limitations in tissue adaptations. The aim of the investigation was to compare histologically the amount of bone formed in an experimentally created parietal bone defect protected with one or two polytetrafluoroethylene membranes with a contralateral control defect. A bony defect was created bilaterally in the parietal bone lateral to the sagittal suture in 29 6-month-old male Wistar rats. The animals were divided into two groups: (1) In the double membrane group (n = 9), the left experimental bone defect was protected by an outer polytetrafluoroethylene membrane under the periosteum and parietal muscles and an inner membrane between the dura mater and the parietal bone. (2) In the single membrane group (n = 20), only the outer membrane was placed. The right defect was not covered with any membrane and served as control. The animals were killed after 30 days. None of the control defects demonstrated complete or partial bone regeneration. In the single membrane group, the experimental site did not regenerate in 15 animals, partially in four, and completely in one. In the double membrane group, six of the experimental defects had complete closure with bone, two had partial closure, and one no closure.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of periosteum in the formation of jaw bone. An experiment in the rat

The aim of the present investigation was to evaluate the bone-forming capacity of the outer (fibrous) and inner (cambium) layer of the mandibular periosteum in skeletally mature rats. The experiment was carried out in 25 rats. The mandibular ramus was exposed on one side (experimental side) after elevation of a muscle-periosteal flap. A teflon capsule was placed with its opening facing the periosteum at the subsurface of the raised muscle-periosteal flap after suturing. In the contralateral side serving as control, the periosteum of the lateral aspect of the mandibular ramus was left intact. This time the teflon capsule was placed with its opening facing the periosteum left behind at the ramus. The histological analysis demonstrated that in all experimental and control specimens, some bone was produced at 7 days after operation. In the experimental specimens, however, both the incidence and the amount of newly-formed bone in the teflon capsules gradually decreased from 7 to 120 days, while increasing in the control capsules placed over the periosteum. At 120 days, the mean amount of new bone produced in the experimental capsules was 3% (range 0-15%) of the total space created by the capsule, while it was 68% (range 41-85%) for the control capsules. The results demonstrated that substantial amounts of bone can be produced predictably by the placement of an occlusive teflon capsule facing mandibular covered with periosteum. Bone produced from the periosteum and without continuity with existing bone becomes resorbed with time.

Use of revascularized periosteal allografts for repairing bony defects: an experimental study

This is an experimental study on the potential of revascularized periosteal allografts for repair of bony defects. Beijing long-eared white rabbits were used as donors and immunologically incompatible Chinchilla rabbits were used as recipients. The periosteum was stripped off from the femurs of the 6 donor rabbits and transplanted to bony defects of 1.2 cm over the radius of the 12 recipients using microsurgical anastomoses of the blood vessels. In the control group of 8 rabbits the same radial bony defects were produced without the transplantation of periosteal grafts. Immunosuppressants were administered after surgery. The animals were observed for 4 months using a series of radiography, histomorphology, fluorochrome labelling and electron microscopy. Results revealed no bony healing of the defects in the control group, but 9 of the 12 defects healed in the experimental group. The results indicated revascularized periosteal allografts were able to form new bone and heal the 1.2 cm radial bone defect in rabbits.

Bone formation by vascularized periosteal and osteoperiosteal grafts. An experimental study in rats

The osteogenic capacity of vascularized periosteal and osteoperiosteal grafts was investigated in 82 Wistar rats about 8 weeks old. The periosteal flaps, pedicled on the descending genicular artery, were taken by stripping the lower third of the femur. In the right hindleg, the grafts were made with periosteum only, while in the left hindleg, the periosteal flaps were associated with cancellous bone. The animals were divided into two groups of 41. In group I, both the periosteal and osteoperiosteal grafts were placed in contact with cortical bone, and in group II, the grafts were buried in muscle. Subgroups of 8 animals were killed after 1, 2, 4, 8, and 16 weeks postoperatively. The grafted region was evaluated radiographically, macroscopically, and histologically. Membranous ossification was the main source of bone formation. Osteoperiosteal grafts produced a greater amount of new bone than periosteal ones. There was evidence that the contact of the graft with living cortical bone favored bone formation.

Vascularized periosteal bone graft from the supracondylar region of the femur

Free, vascularized thin corticoperiosteal grafts and small periosteal bone grafts harvested from the supracondylar region of the femur are described. These grafts are nourished from the articular branch of the descending genicular artery and vein. Thin corticoperiosteal grafts consist of periosteum with a thin layer of outer cortical bone and include the cambium layer, which has a better osteogenic capacity. This graft is elastic and readily conforms to the recipient bed configuration. Thin corticoperiosteal grafts were used to treat 11 patients with fracture non-union of an upper extremity that had no massive bone defects. Early, rapid union occurred in all patients except three: one in which the anastomosed vessel became obstructed and two in which the internal fixation of the fracture was unsecured. The small bone grafts consist of periosteum, full thickness cortex, and the underlying cancellous bone. This graft can be successfully harvested without disturbing the vascularity, unlike the currently used vascularized bone grafts. This graft was used to treat three patients with avascular necrosis of the body of the talus and could prevent the necrotic talus body from progressive collapse in patients in early stages of the disease. One patient with an infectious bone defect of the first metatarsal bone was successfully treated by vascularized bone graft with an accompanying skin flap.

Experimental study of the osteogenic capacity of periosteal allografts: a preliminary report

A total of 16 rabbits were used in this investigation. Beijing long-eared white rabbits served as donors and immunologically incompatible Chinchilla rabbits as recipients. Periosteal flaps were stripped from the femurs of 8 donor rabbits and implanted into the muscles of both thighs of 8 recipients. Revascularization of the grafts was done only on the left side. Immunosuppressants were administered orally beginning the day of surgery. The animals were observed for 1-4 months. A series of radiography, histomorphology, fluorochrome labelling, and electron microscopic examinations were performed. The results demonstrated that all of the revascularized periosteal allografts had new bone formation (8/8), while the nonrevascularized periosteal allografts had none (0/8). The difference in the rate of new bone formation between the two groups was statistically significant.

Periosteal flaps: anatomical bases of sites of elevation

An anatomical study made in 25 injected fresh subjects made it possible to map out the periosteal flaps capable of being raised on the limbs. The preferred donor sites are the distal third of the humerus, the iliac fossa and the distal third of the femur. At the last 2 sites composite osteo-periosteal or musculo-osteo-periosteal flaps can be raised. These technical possibilities illustrate the importance of experimental studies which have shown the osteogenic capacity of grafts of vascularized periosteum.

The reverse flow medial knee osteoperiosteal flap for skeletal reconstruction of the leg. Description and anatomical basis

A new, pedicled, reverse flow osteoperiosteal flap based on 2 branches of the descending genicular a. is presented. Both a periosteal and osteoperiosteal flap can be raised at the distal end of the femur and, in favourable cases (64% of the dissections), transported as far as the middle third of the leg. In all other cases the proximal third of the tibia can be reached. Composite musculo-osteoperiosteal flaps can also be raised, including the articularis genus m. Clinical applications may include the treatment of nonunions, reconstruction of segmental tibial defects and bone revascularisation in aseptic necrosis about the knee joint.

Periosteal microvasculature in the dog alveolar process

Most periodontal surgery has been performed on the basis of the regenerating capacity of the periosteum. Recently it has been pointed out that the blood supply is important to the osteogenic and fibrogenic activity of the periosteum. The purpose of the present study was three-dimensional observation of blood vessels distributed within the gingival periosteum and the periosteum beneath the alveolar mucosa of adult mongrel dogs. Corrosion cast specimens of vessels were observed from three directions: mucosal side, bone side, and horizontal cut surface. It was revealed that the plexus distributed in the periosteum of the gingiva formed a coarse network structure, which consisted mainly of arterioles and venules. In contrast, in the periosteum of the alveolar mucosa, a dense network structure consisting of arterioles, capillaries, and venules formed a vascular bed. Thus, the mucogingival junction was easily located even in the plexus of periosteum which was distributed beneath the gingiva and the alveolar mucosa, suggesting that the difference in tissue specificity was reflected in the plexus of the periosteum.

Osteogenic capacity of vascularised periosteum: experimental study using rib periosteum in rabbits

The osteogenic capacity of vascularised periosteum was investigated in rabbits using island rib periosteum nourished by intercostal vessels as an experimental model. Twenty-three adult white female rabbits were used. Excellent bone formation was observed after 2 postoperative weeks in each case. In the early stages of bone formation, extensive chondral ossification was observed. Newly formed bone became mature after 4 to 8 postoperative weeks, on histological examination.