The temporal sequence of periosteal attachment after elevation

This study investigated the adherence of periosteum to bone after elevation to document the temporal sequence of healing at the periosteal/bone interface. There has been a lack of consensus among surgeons as to the time required for healing at this interface; some believe that the healing achieves significant strength in a few days, whereas others believe that the periosteum does not adhere to the bone for many weeks. The aim of this study was to document the time course for healing, completeness of the reattachment, and structural characteristics of the union of bone and periosteum.To test the hypothesis, scalp flaps were elevated in a subperiosteal plane and were reattached in 40 adult guinea pigs and controls. The individual groups were studied at 3, 6, 12, 30, and 90 days postoperatively. Postmortem study consisted of analysis of the mechanical and histologic findings. Strength of adherence was documented by measuring the force required for reverse avulsion of the flaps with an Instron Mini 44 tensiometer. The specimens were also submitted for electron microscopic examination. The mean tension recorded in the plateau phase of avulsion of the flaps was as follows: controls, 78 g; experimental at 3 and 6 days, not applicable (weak adherence not permitting exposure for reverse avulsion); 12 days, 39 g (p = 0.0001); 30 days, 58 g (p = 0.0012), and 90 days, 63 g (p = 0.0229). There was a significant difference between all groups and the controls. Electron microscopic study showed collagen deposition at the bone periosteal interface, which became progressively more organized in the groups studied at 30 and 90 days, with decreasing amounts of inflammation and inflammatory cells.This study demonstrated that healing at the bone/periosteal interface progresses at a rate consistent with healing of most other wounds, dispelling many widespread beliefs that the adherence at this interface was accelerated. The temporal sequence of healing at the periosteal bone interface should be considered in the various procedures in which periosteal flaps are elevated. For example, there is clinical relevance in subperiosteal brow lift procedures, in which the periosteum should be reattached by a fixation technique that will remain stable for a minimum of 30 days to allow adequate adherence between the bone and periosteum at the postoperative elevated brow position.     

Prefabrication of bone by use of a vascularized periosteal flap and bone morphogenetic protein.

The purpose of this pilot study was to prefabricate a vascularized bone graft by using a vascularized periosteal flap containing osteoprogenitor cells, a structural matrix, and recombinant human bone morphogenetic protein-2 (rhBMP-2). In a rat model, a periosteal flap vascularized by the saphenous artery and vein was dissected off the medial surface of the tibia. This flap consisted of three layers-periosteum, muscle, and fascia-and was tubed on itself to form a watertight chamber that was then transferred on its vascular pedicle to the groin. A total of 78 vascularized periosteal chambers were constructed in 39 animals and divided into 10 groups. In group 1, the periosteal chamber was left empty. Groups 2, 3, and 4 consisted of the periosteal flap and rhBMP-2, but in group 3, the proximal vascular pedicle was ligated, and in group 4, the flap was harvested without the periosteal layer and turned inside out. Groups 5 through 10 consisted of the vascularized periosteal flap containing several different structural matrices (calcium alginate spheres, polylactic acid, or demineralized bone matrix) with or without rhBMP-2. Animals were killed at 2, 4, or 8 weeks in each group. The presence and density of any new bone formation was evaluated both radiologically and histologically. Significant bone formation was seen only in those periosteal flaps containing rhBMP-2 and either the calcium alginate or polylactic acid matrix. New bone formation increased both radiologically and histologically from 2 weeks to 8 weeks only in the periosteal flaps containing the polylactic acid matrix and rhBMP-2. This preliminary study therefore suggests that four factors-blood supply, osteoprogenitor cells in the periosteal layer, a biodegradable matrix, and rhBMP-2-are required for optimal prefabrication of a vascularized bone graft.     

Vascularized periosteum associated with cancellous bone graft: an experimental study

The association of a vascularized periosteal flap with a cancellous bone graft was studied on a group of 20 Wistar rats. Ten rats were sacrificed at 6 weeks and seven at 12 weeks (three died prematurely). The behavior of the cancellous bone graft buried in striated muscle and the osteogenic capacity of a simple vascularized periosteal flap also were observed on the same animals. Results of the study are as follows: In 14 of 17 animals, a vascularized periosteal flap wrapped around a cancellous bone graft resulted in new cortical bone formation with little resorption of the initial cancellous graft. A vascularized musculoperiosteal flap has produced a small amount of new compact bone only in 4 of 17 animals. A cancellous bone graft buried into well-vascularized muscle tissue was resorbed (15 cases) or necrotic (2 cases) at 12 weeks. In conclusion, the association of a vascularized periosteal flap and cancellous bone is a better means to produce compact bone than a vascularized periosteal flap alone or an isolated cancellous bone graft.     

Vascularized periosteal grafts: an experimental study using two different forms of tibial periosteum in rabbits

Three groups of rabbits were studied to investigate the osteogenic capacity of vascularized periosteum. It was found that such tissue, especially in the form of musculoperiosteal flaps, produced a significant amount of bone. It is concluded that vascularized periosteal flaps have an excellent osteogenic capacity even though they are not subjected to weight or stress.     

Prefabricated galeal flap based on superficial temporal and posterior auricular vessels

Scalp layers are widely used in reconstructive procedures. The authors used prefabricated galeal flaps based on the superficial temporal or postauricular vessels for ear, cheek, mandible, and cranium reconstructions in three cases. In case 1, synchronous beard and ear reconstructions were accomplished by using the temporoparietal and retroauricular flaps. In case 2, a buccomandibular defect was reconstructed by transposing the supra-auricular and retroauricular galea with prefabricated bone and skin. In case 3, an epidural hematoma in the left frontoparietal area was evacuated after a circular craniectomy. The harvested bone was not put back on the defect area but buried between the periosteal and galeal layers because of brain edema. These layers were raised as an osteogaleoperiosteal flap and transposed onto the defect area after 7 weeks. When used with a prefabrication method, scalp layers offer versatile options for repairing composite defects of the head region. A galeal flap based on the posterior auricular vessels is practical and reliable in reconstructive procedures. The authors suggest that this flap is an option in cases in which the temporoparietal fascia artery or the superficial temporal artery is not available. Prefabrication of the harvested cranial bone inside the adjacent tissues offers several advantages in that a viable bone is provided at the end of the procedure, intervention at a distant area is avoided, the graft is placed on osteogenic tissue (periosteum) that is also transposed onto the defect, and sophisticated procedures such as microsurgical techniques are not needed.     

Time course for bone formation with long-term external mechanical loading.

Increased mechanical loading of bone with the rat tibia four-point bending device stimulates bone formation on periosteal and endocortical surfaces. With long-term loading cell activity diminishes, and it has been reported that early gains in bone size may reverse. This study examined the time course for bone cellular and structural response after 6, 12, and 18 wk of loading at 1,200-1, 700 microstrain (muepsilon). Bone formation rates, measured by histomorphometry, were compared within groups, between loaded and contralateral nonloaded tibiae, and between weeks. Formation surface, mineral apposition rate, and bone formation rate on periosteal and endocortical surfaces were elevated after 6 wk of loading. By 12 wk of loading, periosteal and endocortical formation surface and endocortical mineral apposition rates were elevated. By 18 wk of loading, periosteal adaptation appeared complete, whereas endocortical mineral apposition rate remained elevated. No periosteal resorption was observed. Average thickness of new bone formed, from baseline to collection, was greater in loaded than nonloaded tibiae by week 6 and was maintained through week 18. Early increases in bone formation result in periosteal apposition of new bone that persists after formation ceases.     

The mechanobiological effects of periosteal surface loads

We have developed an improved mechanobiological model of bone morphogenesis and functional adaptation that includes the influences of periosteum tension and pressure on bone formation and resorption. Previous models assumed that periosteal and endosteal bone deposition and resorption rates are governed only by the local intracortical daily stress or strain stimulus caused by cyclic loading. The new model incorporates experimental findings that pressures on periosteal surfaces can impede bone formation or induce bone resorption, whereas periosteal tensile strains perpendicular to bone surfaces can impede bone resorption or induce bone formation. We propose that these effects can produce flattened or concave bone surfaces in regions of periosteal pressure and bone ridges in regions of periosteal tension. The model was implemented with computer simulations to illustrate the role of adjacent muscles on the development of the triangular cross-sectional geometry of the rat tibia. The results suggest that intracortical stresses dictate bone size, whereas periosteal pressures may work in combination with intracortical stresses and other mechanobiological factors in the development of local bone cross-sectional shapes.     

Investigating the specificity of periosteal reactions in pathology museum specimens

The relationship between periosteal new bone formation and a number of infectious and metabolic conditions frequently seen in archeological human skeletal remains was investigated by studying human long bones demonstrating periosteal new bone formation archived in two London, UK, pathology museums: the St. George's Hospital Pathology Museum and the Hunterian Museum. The samples were subjected to macroscopic and radiographic analysis to determine if the characteristics of their periosteal lesions were specific to the corresponding disease states. The results demonstrated that no qualitative or quantitative characteristics of the periosteal reactions emerged that were specific to individual disease states. It was established that disease progression, rather than disease type, was the most important determinant of periosteal lesion appearance. A critical analysis of the bioarcheology literature pertaining to the recording and interpretation of periosteal reactions determined that the varied pathogenesis of periosteal new bone formation has been largely ignored in favor of a diagnosis of "nonspecific infection." Assumptions regarding the infectious etiology of periosteal lesions have become embedded into the bioarcheology literature potentially skewing the results of skeletal population-based paleoepidemiological studies.     

The inhibition of skeletal changes in a rat burn model with a local muscle flap

The effects of early wound closure using a local muscle flap on the development of periosteal new bone formation in a rat burn model were studied. Following a full-thickness burn to one hind limb, periosteal new bone formation along the tibial diaphysis was measured by the use of the fluorochrome agent calcein and an image-analysis system. Prostaglandin E levels, a known inflammatory mediator, from the bone beneath the burn also were measured. Periosteal new bone formation was inhibited by 50 percent in animals that had debridement and wound closure with a gastrocnemius muscle flap and skin graft on postburn day 2 compared to untreated controls or animals closed with skin grafts only. There was a trend toward reduced prostaglandin E measurements from tibial sections in the early closure group compared to untreated controls. This study demonstrates that early wound closure using a local muscle flap inhibits the periosteal new bone formation which is possibly associated with the inflammation in a rat burn model.     

A three-dimensional ultrastructural study of osteoid-osteocytes in the tibia of chick embryos

Summary Morphology and ultrastructure of osteoid-osteocytes were studied in serial thin sections (700–800 Å thick) of periosteal woven bone in tibiae of 15-day-old chick embryos. The three-dimensional shapes of 21 partially, and of one fully sectioned cell were reconstructed manually and by means of a computer-assisted image analyser.Osteoid-osteocytes are active cells engaged in organic matrix secretion and calcification. Like osteoblasts, their activity seems to be polarized towards the mineralization front, as shown by the presence of cytoplasmic processes on their mineral-facing side and by the position of the nucleus toward the vascular side of the cytoplasm. Cellular processes directed towards blood vessels appear only at a later stage, i.e. when the mineralization starts to spread all round the cell.The asynchrony in formation, together with the observed differences in morphology suggest the hypothesis that the cellular processes of the mineral-facing side are mainly involved in bone formation and those of the vascular side in cell nutrition.     

The use of a temporal osteoperiosteal flap for the reconstruction of malar hypoplasia in Treacher Collins syndrome

The clinical use of a temporal periosteal bone flap for the reconstruction of a malar bone in a patient with the Treacher Collins syndrome is presented. The temporal muscle functions as an axial carrier of the periosteum that induces osteogenesis in young children, whereas the bone segments may serve as a nucleus for further bone formation from the periosteum. Correction of the eyelid coloboma was obtained by the rotation and advancement of a temporopalpebral flap.     

Computational simulation of spontaneous bone straightening in growing children

Periosteal surface pressures have been shown to inhibit bone formation and induce bone resorption, while tensile strains perpendicular to the periosteal surface have been shown to inhibit bone resorption and induce new bone deposition. A new computational model was developed to incorporate these experimental findings into simulations of spontaneous bone straightening in children with congenital posteromedial bowing of the tibia. Three-dimensional finite element models of the periosteum were used to determine the relationships between the defect angle and the distribution of bone surface pressures and strains due to growth-generated tensile strains in the periosteum. These relationships were incorporated into an iterative simulation to model development of a growing, bowed tibia with an initial defect angle of 27°. When periosteal loads were included in the simulation, the defect angle decreased to 10° after 2 years, and the bone straightened by an age of 25 years. When periosteal loads were not included in the simulation, the defect angle decreased to 23° after 2 years, and a defect angle of 9° remained at an age of 25 years. A “modeling drift” bone apposition/resorption pattern appeared only when periosteal loads were included. The results suggest that periosteal pressures and tensile strains induced by bone bowing can accelerate the process of bone straightening and lead to more complete correction of congenital bowing defects. Including the mechanobiological effects of periosteal surface loads in the simulations produced results similar to those seen clinically, with rapid straightening during the first few years of growth.     

Tomographical description of tennis-loaded radius: reciprocal relation between bone size and volumetric BMD.

Effects of long-term tennis loading on volumetric bone mineral density (vBMD) and geometric properties of playing-arm radius were examined. Paired forearms of 16 tennis players (10 women) and 12 healthy controls (7 women), aged 18-24 yr, were scanned at mid and distal site by using peripheral quantitative computerized tomography. Tomographic data at midradius showed that tennis playing led to a slight decrease in cortical vBMD (-0.8% vs. nonplaying arm, P < 0. 05) and increase both in periosteal and endocoritcal bone area (+15. 2% for periosteal bone, P < 0.001; and +18.8% for endocortical bone, P < 0.001). These data suggest that, together with an increase in cortical thickness (+6.4%, P < 0.01), cortical drift toward periosteal direction resulted in improvement of mechanical characteristics of the playing-arm midradius. Enlargement of periosteal bone area was also observed at distal radius (+6.8%, P < 0.01), and the relative side-to-side difference in periosteal bone area was inversely related to that in trabecular vBMD (r = -0.53, P < 0.05). We conclude that an improvement of mechanical properties of young adult bone in response to long-term exercise is related to geometric adaptation but less to changes in vBMD.     

Frontal bone periosteal osteomas

Osteomas are the most common tumors of the cranial vault and facial skeleton. Osteomas are usually benign in nature, commonly presenting with symptoms of facial deformity, facial pain, and headaches. Although the frontal sinus is the most frequent location of cranial osteomas, they are also occasionally seen involving only the frontal bone periosteum. This study is a retrospective series investigating the characteristics, management, and outcomes of five patients with frontal bone periosteal osteomas surgically treated with superficial osteotomies with primary closure. Medical charts were reviewed focusing on symptoms, size, radiographic findings, and disease of the periosteal osteomas. The chief complaint primarily involved a palpable deformity, which led to surgical evaluation. Radiographic studies were obtained to evaluate size and location of the frontal osteomas. Microanalysis of the specimens confirmed the presence of mature cancellous and/or cortical bone. Postoperative follow-up revealed no evidence of recurrence or complications. The superficial ostectomy technique with primary closure offers a simple, effective method for removal of frontal bone periosteal osteomas with minimal side effects.     

Reconstruction of facial defects with superficial temporal artery island flaps: a donor site with various alternatives

Color and texture match is crucial in reconstruction of facial tissue defects. Between March of 1997 and July of 2000, island flaps based on the parietal, anterofrontal, centrofrontal, posterofrontal, and superior auricular branches of the superficial temporal artery were used in the reconstruction of tissue defects localized on different regions of the face in 28 patients. According to the size and the location of the defect, the flap was selected. There were 15 male patients and 13 female patients, with ages ranging between 19 and 74 years. In six of the flaps, venous congestion was observed. Because of the elevation of the eyebrow on the flap side, three patients required a sling to the opposite eyebrow. Excellent color and tissue match and transfer of hair-bearing tissue to the eyebrow and beard areas were achieved with no other complications. Satisfactory aesthetic results were gained.     

On an attempt to treat primary and secondary osteoporosis with human growth hormone.

Three male patients with severe osteoporosis were treated with human growth hormone. One of them had a primary osteoporosis, the two others osteogenesis imperfecta. The duration of therapy was 8 to 15 months and average doses per day were 1.45 to 2.3 mg. While clinical and 47calcium kinetic data failed to prove marked influences of the treatment, histomorphometry of bone biopsies showed indisputable changes. There was an increase of periosteal new bone formation as well as of intracortical bone resorption, while at the same time the relative activity of osteoblasts on endosteal surfaces showed a significant increase.     

Revascularized periosteal grafts--a new method to produce functional new bone without bone grafting

Rib periosteum was transplanted to the groins of 9 dogs. In half of the periosteal grafts, no microvascular anastomoses were done (free grafts); at 6 weeks after grafting they had become resorbed. The other periosteal grafts were revascularized by microvascular anastomoses of the intercostal vessels to local muscular vessels; at 6 weeks those with confirmed vascular patency had all formed substantial amounts of new bone. Five cm, full-thickness defects were created in the tibias of 10 dogs. The control animals (without grafting) did not heal in two months. However, the experimental dogs, with vascularized periosteal grafts in the defects regenerated their tibias with healthy new bone by 6 weeks--and were walking on them then.     

Mechanistic,Mathematical Model to Predict the Dynamics of Tissue Genesis in Bone Defects via Mechanical Feedback and Mediation of Biochemical Factors

The link between mechanics and biology in the generation and the adaptation of bone has been well studied in context of skeletal development and fracture healing. Yet, the prediction of tissue genesis within - and the spatiotemporal healing of - postnatal defects, necessitates a quantitative evaluation of mechano-biological interactions using experimental and clinical parameters. To address this current gap in knowledge, this study aims to develop a mechanistic mathematical model of tissue genesis using bone morphogenetic protein (BMP) to represent of a class of factors that may coordinate bone healing. Specifically, we developed a mechanistic, mathematical model to predict the dynamics of tissue genesis by periosteal progenitor cells within a long bone defect surrounded by periosteum and stabilized via an intramedullary nail. The emergent material properties and mechanical environment associated with nascent tissue genesis influence the strain stimulus sensed by progenitor cells within the periosteum. Using a mechanical finite element model, periosteal surface strains are predicted as a function of emergent, nascent tissue properties. Strains are then input to a mechanistic mathematical model, where mechanical regulation of BMP-2 production mediates rates of cellular proliferation, differentiation and tissue production, to predict healing outcomes. A parametric approach enables the spatial and temporal prediction of endochondral tissue regeneration, assessed as areas of cartilage and mineralized bone, as functions of radial distance from the periosteum and time. Comparing model results to histological outcomes from two previous studies of periosteum-mediated bone regeneration in a common ovine model, it was shown that mechanistic models incorporating mechanical feedback successfully predict patterns (spatial) and trends (temporal) of bone tissue regeneration. The novel model framework presented here integrates a mechanistic feedback system based on the mechanosensitivity of periosteal progenitor cells, which allows for modeling and prediction of tissue regeneration on multiple length and time scales. Through combination of computational, physical and engineering science approaches, the model platform provides a means to test new hypotheses in silico and to elucidate conditions conducive to endogenous tissue genesis. Next generation models will serve to unravel intrinsic differences in bone genesis by endochondral and intramembranous mechanisms.     

Does interference with mucoperiosteum and palatal bone affect craniofacial growth? An experimental study in beagles

This study was designed to assess the effects of raising mucoperiosteal flaps and exposing palatal bone at the time of palatoplasty. Using 62 beagle puppies as subjects, we tested the hypothesis that raising mucoperiosteal flaps does not interfere with craniofacial growth. We further hypothesized that the size of the area of bone exposed following palatoplasty does affect subsequent craniofacial growth. The animals were divided into four groups: two control groups (unoperated and unrepaired) and two experimental groups. In the first experimental group, two-flap palatoplasty was used to close the surgically induced palatal defect, leaving narrow strips (0 to 2.5 mm) of bone exposed lateral to the flaps. In the second group, one flap was raised to close the defect, leaving a wide area (5 to 6 mm) of palatal bone exposed on one side. Thirty-four direct craniometric measurements were analyzed. Animals that had elevation of both mucoperiosteal flaps with narrow strips of denuded bone on both sides had less severe craniofacial growth aberrations than those in which the defect was left unrepaired or was repaired with one mucoperiosteal flap leaving a wider area of bare bone exposed. These findings suggest that raising mucoperiosteal flaps is less detrimental to craniofacial growth than leaving large areas of exposed palatal bone.