Experimental vascularized bone transplantations

The postoperative hypertrophy of the vascularized fibula graft is of particular interest. In order to clarify the etiology of the hypertrophy, we conducted experimental projects on vascularized bone grafts using fluorochrome bone labelings, histomorphometry and measurement of blood flow in rats and rabbits. In the murine vascularized tibio-fibula graft for bone defects of the tibia, where mechanical stress to the graft can be expected, cross-sectional bone growth was maintained with acceleration of new bone formation and an alteration of growth direction at 3 weeks after the transplantation. In vascularized bone grafts where no mechanical stress to the graft is expected, more bone resorption was seen than bone formation. In the murine tail bone graft to a bony defect of the femur, the cancellous bone gradually disappeared, and the trabeculae took on an architecture characteristic of the femur. This process slowly transforms the graft into a femur with the morphologic features of a long bone. These results suggested that remodeling of the graft corresponding with the changes in the dynamic environment was accompanied by adequate resorption. The cross-age transplantation of vascularized tibio-fibula grafts in rats showed that the younger the donor, the faster the hypertrophy. Age is one of the important factors affecting remodeling of the vascularized bone graft. The blood flow of the grafted bone in the rabbits increased immediately after the transplantation as a reaction to surgery. Thereafter the blood flow of the graft may depend on the biological demands for new bone formation in adapting to the biomechanical environment of the recipient site.

The anatomic basis of a free vascularized bone graft based on the canine distal ulna

The anatomy of the canine distal ulna was evaluated to determine its potential as a free vascularized bone graft. Twelve cadavers were studied by gross dissection and nonselective and selective angiography. The caudal interosseous artery consistently served as a source artery to the distal ulnar periosteal vasculature in all dogs. The diameters of the caudal interosseous artery and venae comitantes were large enough to permit microvascular anastomoses. Nonselective perfusions of the brachial artery demonstrated large barium-filled vessels within soft tissues surrounding the ulna with anastomotic connections between medullary and periosteal vasculature. Grafts selectively perfused through the caudal interosseous artery (periosteal circulation only) had barium-filled vessels within the muscular cuff, periosteum, cortical bone, and medullary canal of the ulna. A surgical approach to remove the distal ulna along with an intact musculoperiosteal cuff and its associated vasculature is described.

Total elbow allograft for twice-failed total elbow arthroplasty. A case report

A successful case of total elbow allograft after removal of a twice-failed total elbow prosthesis is reported. The patient, a disabled 63 year old at the time of allograft implantation, can now perform all activities of daily living, including household chores. Both the humeral and ulnar allografts have incorporated, and there is no evidence of degenerative changes or allograft resorption two years nine months postoperatively.

Heterotopic vascularized growth plate transfer in juvenile dogs

Prior animal studies of vascularized epiphyseal transfers placed growth plates in 2 bone systems where the independent growth of epiphyses and their response to altered stresses has been difficult to assess. This study assessed growth of vascularized ulnar epiphyses transferred to the ipsilateral humerus of 12-week-old puppies. Growth was permitted by a specially designed extensible plate. Control groups showed that humeral dissection, osteotomy and ostectomy alone do not stimulate growth. In 4 puppies initial growth of the transferred epiphysis was seen but late collapse and formation of bridging callus occurred so that overall humeral length at maturity was not significantly different from control humeri. Physical forces inherent in heterotopic transfer may preclude long term growth of transferred epiphyses particularly in sites of higher relative load. The extensible plate used here may be a useful device in the fixation of transferred epiphyses with growth potential.

Quantitative histologic study of the influence of anterior spinal instrumentation and biodegradable polymer on lumbar interbody fusion after corpectomy. A canine model

Histomorphometric and microradiographic studies were performed to investigate whether there are different rates of bone remodeling based on the intrinsic stability with anterior spinal instrumentation and to evaluate if biodegradable polymer could be used clinically as the material of choice for anterior spinal instrumentation. Twenty-one coon hounds underwent anterior and posterior spinal destabilizing procedures to produce a reproducible amount of spinal instability: corpectomy of L5, discectomies and partial facetectomies of L4-5 and L5-6, resections of L5 lamina, spinous process, supra- and interspinous ligament, and ligamentum flavum. Group 1 (N = 7) underwent anterior autogenous ulna strut graft alone at L4-6; group 2 (N = 7) underwent anterior biodegradable polymer strut alone at the same level; group 3 (N = 7) underwent same bone graft as in group 1, augmented by anterior Kaneda device. Six months after surgery quantitative histologic study showed that device-related osteopenia occurred in spines treated with Kaneda device. Within the L5 vertebral body the volumetric density of bone (mm3/cm3) was less for the group with Kaneda device (group 3) compared with that without instrumentation (group 1, P less than 0.05). In the spine treated with biodegradable polymer, no adverse host tissue responses were observed histologically. In addition, osteoconductive abilities of the polymer were suggested microscopically. Its mechanical property, however, was not rigid enough to stabilize the corpectomized spine.

The olecranon bone graft for nasal augmentation

The olecranon bone graft offers an alternative to the cranial bone when autogenous material is preferred in the repair of moderate deficiencies of the nasal dorsum. The predictably thick cortex of the olecranon allows the crafting of a customized implant, and minimal donor site morbidity makes it a safe alternative to the cranial graft.

Arthrodesis of the wrist by a new technique

Twenty-eight arthrodeses of the wrist were carried out for various indications using an ulnar graft. The results were evaluated and it was found that the obliquely resected lower end of the ulna gave a longer graft for better fusion between the distal end of radius and the base of the 3rd metacarpal. There was no instability of the inferior radio-ulnar joint, and rotation of the forearm was improved whenever it had been previously limited.

Single stage reconstruction of a large tibial defect using a free vascularised osteomyocutaneous ulnar transfer

We present the case of a young man with 13 cm of bone and soft-tissue loss in the tibia and a severe traction injury of the brachial plexus. A free vascularised composite transfer of the bone and soft tissues of the ulnar side of the forearm was undertaken to reconstruct the defect. Bony union was achieved after a year and was followed by complete functional recovery of the lower limb.

Organization of positional information in the axolotl limb

We have used the phenomenon of position-dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. When either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. However, transplants of humerus or radius into anterior or ventral positions did not lead to the formation of any additional digits. The ulna by contrast was capable of stimulating supernumerary digit formation when transplanted into anterior, posterior, dorsal, or ventral positions. We interpret these results to indicate that the humerus and radius are surrounded by symmetrically arranged anterior and ventral positional values, whereas the ulna is surrounded by a complete asymmetrical set of angular positional values. We use our proposed arrangement for the positional information in the limb center to explain a number of previous experimental findings. In addition, we provide an explanation, in terms of the underlying positional information, for the structural and developmental relationships between the different skeletal elements of the vertebrate limb, and in particular for the anatomical pattern known as Gregory's pyramid.

Thumb reconstruction by the posterior interosseous osteocutaneous flap

An island osteo-fasciocutaneous flap, based on the posterior interosseous vessels, is described for thumb reconstruction. The artery supplies the fascial plexus of the posterior forearm as well as the superficial and deep extensor muscles. A vascularised bone segment of the upper third of the ulna can be harvested, including a cuff of the extensor pollicis longus muscle. The flap was used successfully in two clinical cases.

Experimental vascularized bone grafts: histopathologic correlations with postoperative bone scan: the risk of false-positive results

A positive bone scan in an experimental model of bilateral ulna diaphyseal bone grafts demonstrated early bone repair in both vascularized and nonvascularized orthotopic ulna autografts. A positive bone scan did not correlate with the perfusion of the vascularized and nonvascularized grafts as measured by microangiograms done 1 week postoperatively. In this model, if the bone scan is intended to monitor the circulatory status and viability of the bone graft, it must be done earlier than 1 week postoperative prior to the onset of creeping repair in both vascularized and nonvascular ulna autografts.

Modified instruments for wrist fusion

A technique and new instruments for intramedullary fixation of the wrist arthrodesis is described, based on the technique of Clayton, popularized by Nalebuff and Millender. This allows early mobilisation, secure fixation and simplicity of the technique. It also allows other surgical procedures to be performed under the same anaesthetic and tourniquet due to the reduction in operative time.

Canine cortical bone autograft remodeling in two simultaneous skeletal sites

The morphological and physical aspects of cortical bone autografts implanted in dogs for 1-9 months in two differently located skeletal defects are reported with a twofold aim: to provide a reference system for further comparison with various allografts and to delineate a general pattern of cortical bone graft healing. A 3-cm osteoperiosteal gap was created in the diaphyseal segment of the ulna and fibula of mature dogs. The grafts, freed from periosteum and bone marrow, were then inverted and replaced for the autografts in the left limb bone without internal fixation or external splints. On the right side, different allografts were tested. A group of three animals also had an unfilled segmental resection on the right as control. Dogs were observed for 1, 2, 3, 6, and 9 months and were able to bear weight within 3 days. Twenty-eight ulnae and 27 fibulae were available for this autograft study. Fluorochromes were injected at mid-term and at the end of the observation. All the grafts were assessed morphologically by cross-section microradiographs and ultraviolet light microscopy, and a morphometric analysis for porosity and fluorescence was done. To evaluate the physical aspects of graft healing, the recovered ulnar autografts, when available, were submitted to photon absorptiometry and to torsional loading. Morphologically, resorption was found to invade the cortical bone graft transversely through radial tunnels, and in addition to the host-bone-graft junction, the entire transplant surface provided another way for revascularization. The highest porosity level was achieved 2 months after surgery for both ulna and fibula, while new bone formation, as assessed by fluorochromes, was most important at 3 months. At 9 months, porosity remained above the normal range as determined in a set of five nongrafted dogs. While the lack of correlation for porosity between the two grafts suggests that local factors are more important in graft resorption, the observed correlation for fluorescence indicates that new bone deposition is more dependent upon skeletal metabolic activity. Within each graft, porosity and new bone formation were not well correlated. In the ulna, the bone mineral content (BMC) reflected the graft volumetric variations during the remodeling, with the lowest mean value at 3 months. For each graft, BMC was well correlated with the torsional stiffness. When torsionally loaded, the maximal tangential shear stress at failure of the graft was negatively related to its cortical porosity.(ABSTRACT TRUNCATED AT 400 WORDS)

Retinoic acid modifies positional memory in the anteroposterior axis of regenerating axolotl limbs

The effects of retinoic acid (RA) on anteroposterior (AP) positional memory of regenerating axolotl limbs were tested after removing the anterior or posterior half from the zeugopodium (lower arm or leg). RA (150 micrograms/g body wt) was injected into groups of animals bearing the following types of limbs: (1) anterior and posterior half zeugopodia grafted to the eyesocket and amputated distally 7 days later; (2) unamputated anterior and posterior half zeugopodia in situ; (3) double anterior and double posterior half zeugopodia amputated distally 7 days after their construction; (4) sham-operated zeugopodia amputated distally 7 days after operation. Controls consisted of these four groups injected with the retinoid solvent, dimethyl sulfoxide, or not injected. Control half zeugopodia grafted to the eyesocket regenerated no more than one or two digits. Control unamputated half zeugopodia in situ underwent partial or complete regeneration of the missing half from the proximal and midline wound surfaces exposed during construction of the half zeugopodia. Control double anterior and posterior zeugopodia both regenerated symmetrical, hypomorphic regenerates with 1-3 digits in the double anteriors and 1-6 digits in the double posteriors. Sham-operated controls regenerated normally. Regenerating anterior and posterior halves responded differently to RA. RA-treated anterior half zeugopodia in the eyesocket, and anterior half stumps adjacent to the unamputated posterior half zeugopodia in situ both produced regenerates that duplicated stump structures in the proximodistal axis and formed a complete and normal AP pattern. RA-treated double anterior zeugopodia regenerated proximodistal-duplicated pairs of mirror-imaged limbs, each with a complete and normal AP pattern. In contrast, half posterior zeugopodia in the eyesocket, the posterior half stumps of unamputated half anterior zeugopodia in situ, and double posterior zeugopodia all failed to regenerate. These results suggest that RA modifies positional memory in only one direction in the AP axis, posterior.

Cortical bone grafts with muscle pedicles. An experimental study of survival and ability to bridge a bone gap

A cortical bone graft on a muscle pedicle was taken from the ulna and transferred to bridge a complete defect of the radius in 16 dogs. In 14 control dogs a free graft was used, that is, one without a muscle pedicle. Union in the group with pedicle grafts was far superior to that in the group with free grafts, mainly because in those with pedicle grafts there was good subperiosteal new bone formation from active viable periosteum. In six of the pedicle grafts the viability of some osteocytes was retained over a 12-week period and in five the graft was almost completely replaced by new bone.

Fate of vascularized and nonvascularized autografts

Controlled laboratory data demonstrate biologic and mechanical characteristics of orthotopically placed canine ulnar autografts. The pattern of bone repair was similar in vascular and nonvascular ulnar grafts beginning with resorption followed by appositional reactive bone formation. The time intervals in the sequence were accelerated in the vascularized grafts. Both the strength and stiffness of the vascularized grafts were found to be significantly greater in Groups studied from six weeks to six months postoperation. There was no statistical difference between the grafts for mechanical testing performed on dogs either one week or one year postoperation. The vascularized ulnar bone grafts fared better than comparably sized nonvascularized grafts and were more rapidly repaired. The mechanical testing demonstrated superior strength and stiffness of the vascularized grafts throughout the repair process.

Bone grafting: role of histocompatibility in transplantation

The role of histocompatibility matching in bone allografting was studied in two canine bone graft models. In a cancellous ulnar segmental replacement model, frozen bone allografts exchanged between closely matched dogs were significantly better incorporated by radiographic and histologic criteria than were strongly incompatible grafts. Frozen allografts from disparate donors in recipients receiving immunosuppression appeared indistinguishable 6 months later from those in the untreated closely matched groups and from fresh autografts. Fresh vascularized orthotopically placed fibular bone grafts were evaluated by quantitative blood flow assessment, microangiography, and fluorochrome histomorphometry. Revascularized grafts exchanged between untreated closely matched dogs demonstrated preservation of blood flow and a pattern of repair that was delayed but not otherwise different than vascularized autografts. These results suggest that fresh vascularized grafts in the judiciously matched or immunosuppressed recipient offer attractive clinical possibilities.

Closure of a defect of the femur with a compound free forearm transfer including both the radius and the ulna

We report our experience of a patient with a most unusual and unfortunate combination of injuries. We feel that this case demonstrates not only the value of vascularised bone grafts in the treatment of large defects but also the imaginative use of seemingly useless parts in surgical reconstruction.

Osteoinductivity of partially decalcified alloimplants in healing of large osteoperiosteal defects

About 3.5 cm osteoperiosteal circumferential gaps in rabbit ulnae were bridged by partially decalcified (by 0.6 M HCl) allogenic implants, 8-12 weeks after implantation complete bridging of the gap by new bone formation and union at host-graft junctions was observed in 97.2 per cent of the experiments. Instant permeability and the powerful osteo-inductive potential of the implant coupled with some degree of mechanical stability provided by partial decalcification ensured successful bone formation in almost all the experiments. It is suggested that partially decalcified allogenic bone matrix preserved in 70 per cent ethanol may be a reasonably good substitute for autologous bone graft.

Free microvascular epiphyseal transplantation: an experimental study in dogs

Orthopic and heterotopic microvascular epiphyseal transplants based on periosteal blood supply were performed in 2 experiments. Heterotopic transplants averaged 69 per cent of growth of non-operated control bones. Orthopic transplants achieved a better result but the number of dogs available for evaluation was too small to be conclusive. The question is raised whether additional blood supply to the epiphyseal side of the transplant could improve the results.

Growth in revascularized bone grafts in young puppies

The results of microvascular transfers of growing ulnas in puppy forelegs have been studied. These transfers were carried out both heterotopically and orthotopically. The growth in the revascularized bone grafts has been compared to that in heterotopic, nonvascularized ulna transfers and to normal ulnar growth. The growth in the vascularized bone grafts was significantly greater than in the nonvascularized grafts, but significantly less than in normal ulnar growth. A metaphyseal contribution to the blood supply of the growing portion of long bones is suggested.

Compression treatment of long bone pseudarthroses

In 122 cases of non-union and delayed union, rigid fixation with Swiss compression plates without the use of casts, produced 92.6% success with the first operation. Half of the cases, especially in the well aligned fractures with hypertrophic callus, were treated without bone grafts and without resecting the pseudarthrosis. Non-resection did not adversely affect the healing time or rate. There were 9 failures or 7.4% chiefly in the difficult hypovascular atrophic bone-grafted group. Many of these cases were treated with shingling and grafts as well; 4 cases showed signs of healing but refractured secondary to trauma; 4 of 5 failures were replated and eventually healed. About 83% of the 24 infected cases healed with one compression plate operation. All of the fractures that were dry pre- and post-operatively united. In a few with drainage and poor skin coverage or cicatrix, rigid fixation with external fixators and Steinmann pins were applied. Early active exercises with delayed weight-bearing until union, gave remarkable return of function even in the difficult metaphyseal pseudarthroses. The compression method of rigid fixation is an excellent adjuvant to pseudarthrosis therapy.

Prevention and treatment of non-union of slightly displaced fractures of the lateral humeral condyle in children. An end-result study

In a ten-year study of the healing responses of thirty-one children with fresh fractures of the lateral condyle of the humerus with less than four millimeters of displacement, there were three patterns of healing. Forty-nine per cent healed rapidly in six weeks with abundant callus and periosteal new bone. Thirty-eight per cent healed slowly over eight to twelve weeks, mostly by endosteal union with little callus. Thirteen per cent had progressive displacement of the fragment in the plaster cast and required surgery to prevent non-union. Those fractures that healed had two millimeters or less of displacement of the fragment initially. Those that did not heal had an average of three millimeters of initial displacement. Established non-unions in good position that were symptomatic while the elbow was still immature were salvaged by bone-grafting, sparing the physis of the condylar fragment. The fragment united and grew with the elbow to maturity, producing an excellent end result on long-term follow-up. When the physeal plate of the ununited condylar fragment was absent, the fragment could not grow with the elbow and the result of surgery was less satisfactory.