Experimental microvascular growth plate transfers. Part I--Investigation of vascularity

Total hip reconstruction after sarcoma resection in children with a free vascularized fibula without osteotomy of the bone flap: Technique description and case series

BACKGROUND

Hip joint reconstruction following intra-articular resection of the femoral head in children is a highly demanding challenge. We aimed to describe the outcomes of hip reconstruction in paediatric patients with a free fibular epiphyso-diaphyseal flap based on both anterior tibial and peroneal vessels within a radius allograft.

PATIENTS AND METHODS

Four patients underwent hip reconstruction following this technique between 2013 and 2020 at La Paz University Hospital (Madrid, Spain). The postoperative follow-up period ranged between 12 months and seven years. Two of the patients were diagnosed with Ewing's sarcoma and two with osteosarcoma. The median age at the time of surgery was eight years (six to nine).

RESULTS

Three patients remained to be disease-free at the time of this study, and one died shortly after surgery, so he was excluded from the reconstruction analysis of results. No postoperative complications requiring reintervention were recorded. Imaging studies (X-ray and MRI) showed three-dimensional growth of the flap and integration of the allograft. Mean leg length discrepancy was 1.3 cm (0 to 2.3). At the last follow-up visit, all patients were able to ambulate.

CONCLUSION

For children following oncological resection of the femoral head, reconstruction with a vascularized epiphyso-diaphyseal fibula flap combined with radius allograft is a safe option. This procedure provides encouraging functional results and avoids the complications of previously published techniques or implants.

Transplantation of a Scaffold-Free Cartilage Tissue Analogue for the Treatment of Physeal Cartilage Injury of the Proximal Tibia in Rabbits

PURPOSE

The purpose of this study was to investigate the effects of transplantation of an in vitro-generated, scaffold-free, tissue-engineered cartilage tissue analogue (CTA) using a suspension chondrocyte culture in a rabbit growth-arrest model.

MATERIALS AND METHODS

We harvested cartilage cells from the articular cartilage of the joints of white rabbits and made a CTA using a suspension culture of 2×10⁷ cells/mL. An animal growth plate defect model was made on the medial side of the proximal tibial growth plate of both tibias of 6-week-old New Zealand white rabbits (n=10). The allogenic CTA was then transplanted onto the right proximal tibial defect. As a control, no implantation was performed on the left-side defect. Plain radiographs and the medial proximal tibial angle were obtained at 1-week intervals for evaluation of bone bridge formation and the degree of angular deformity until postoperative week 6. We performed a histological evaluation using hematoxylin-eosin and Alcian blue staining at postoperative weeks 4 and 6.

RESULTS

Radiologic study revealed a median medial proximal tibial angle of 59.0° in the control group and 80.0° in the CTA group at 6 weeks. In the control group, statistically significant angular deformities were seen 3 weeks after transplantation (p<0.05). On histological examination, the transplanted CTA was maintained in the CTA group at 4 and 6 weeks postoperative. Bone bridge formation was observed in the control group.

CONCLUSION

In this study, CTA transplantation minimized deformity in the rabbit growth plate injury model, probably via the attenuation of bone bridge formation.

The use of free vascularized fibular grafts in skeletal reconstruction for bone tumors in children

The reconstruction of large skeletal defects in children following resection of a bone tumor presents a unique challenge to the orthopaedic surgeon. Issues in this population that are not present in the adult population include significant remaining growth potential, the desire for biologic preservation of the joint surface, and the need for a long-term viable reconstruction in patients who are anticipated to survive for decades. The use of a free vascularized fibular graft, supplied by the peroneal vessels in intercalary fibular grafts and the anterior tibial vessels in proximal fibular grafts, has been shown to provide biologic reconstruction that successfully addresses these issues in the pediatric population. Specific techniques are applied in the upper and lower extremity to provide long-term excellent functional results. Experience in microvascular surgery and careful postoperative care are required for the success of these procedures.

Vascularized epiphyseal transplant

In skeletally immature patients, the transfer of vascularized epiphysis along with a variable amount of adjoining diaphysis may provide the potential for growth of such a graft, preventing future limb length discrepancy. This article describes the authors' experience with the vascularized transfer of the proximal fibular epiphysis in the reconstruction of large bone defects including the epiphysis in a series of 27 patients ranging in age from 2 to 11 years. The follow-up, ranging from 2 to 14 years, has been long enough to allow some evaluation of the validity, indications, and limits of this reconstructive option.

Microvascular transplantation of epiphyseal plates: studies utilizing allograft donor material

Compromised function of an epiphyseal plate caused by trauma, tumor, infection, or congenital malformation can result in significant musculoskeletal deformity. Techniques used to correct or minimize the extent of these deformities include autogenous or allogeneic cancellous bone grafts, nonvascularized cortical allografts, vascularized bone and composite tissue transfers, and distraction osteogenesis. These solutions are not ideal for children because they do not adequately address the actively growing nature of the extremity. Microvascular techniques have enabled the experimental transplantation of vascularized epiphyseal plates with high levels of postoperative viability and subsequent growth and offer a potential advantage over conventional treatments.

Treatment of rabbit growth plate injuries with an autologous tissue-engineered composite. An experimental study

Tissue engineering has become a promising way of treating growth plate injuries. In this study, we attempted investigating the role of the autologous tissue-engineered composite in the treatment of rabbit growth plate injuries. Growth plate chondrocytes from iliac crest epiphyseal cartilage of immature New Zealand rabbits were obtained by dissection and sequential digestion with 0.2% collagenase (type II). After proliferating in monolayer culture in vitro for 3 weeks, the cells were harvested and seeded onto the demineralized bone matrix (DBM) scaffold to construct the composite. The autologous tissue-engineered composites were finally implanted into the proximal right tibia defects of the growth plate created in 12 rabbits (group A underwent the operation after obtaining chondrocytes 3 weeks beforehand), another 12 rabbits were implanted with only the DBM scaffold (group B), and the defects in group C (12 rabbits) were not implanted. The left tibias of all animals were left undone as the normal control. Two weeks after the operation, severe shortness and angulation deformity of the right tibia evaluated by X-ray were gradually observed in groups B and C. However, there were no obvious changes in group A and there were significant differences between group A and groups B and C (p < 0.05) at the 4-, 8-, and 16-weeks time points. 16 weeks after operation, histological examination revealed that the defects of the right tibias in group A had restored to almost the normal columnar structure of the growth plate. The results demonstrate that tissue-engineered composite established by combination of autologous growth plate chondrocytes and DBM can prevent the formation of a bone bridge and restore the growth of damaged growth plate.

Epiphyseal transplant: Harvesting technique of the proximal fibula based on the anterior tibial artery

Epiphyseal transplants in children were introduced into clinical practice about 20 years ago. Among possible donor sites, the proximal fibula is definitely the most popular choice, and has been used mainly for reconstruction of the proximal humerus and distal radius. Provided that an adequate blood supply both to the physis and to the diaphysis must be restored in order to obtain acceptable axial growth of the transferred fibula and a bone fusion at the osteotomy site, the choice of feeding pedicle is still a controversial issue. Our contribution involves a homogeneous series of 24 patients under 11 years of age who had skeletal reconstruction in the upper limb by means of a vascularized transfer of the proximal fibula based on the anterior tibial artery. The aim of the present paper is to describe in detail the harvesting technique which has been partially modified and gradually refined in our 10-year experience.

Vascularized Fibular Epiphyseal Transplantation for Limb Salvage Following Bone Tumour Excision

Vascularized fibular transplantation has found wide application for long bone reconstruction in both congenital and acquired defects. However, in children the growth of these transplants is limited and requires the epiphysis if it is to be substantial. Also, the reconstruction of a joint is best achieved with autologus hyaline cartilage. Vascularized fibular epiphyseal transplantation, thus, may play a role in limb salvage procedures in children to both preserve joint function and facilitate long bone growth. The present paper discusses the history of vascularized epiphyseal transplantation both in the laboratory and clinical realm. In discussing its advantages and associated problems, special emphasis is directed at the vascular factors, the endocrine environment, the innervation, mechanical stressors, the recipient site and the donor site. Two case examples are presented to demonstrate the technique, the results and the long term outcome.

Distraction and microvascular epiphysis transfer for radial club hand

This paper presents a different technique of treatment for Bayne type IV radial club hand using a microvascular joint transfer in order to reconstruct the absent half of the wrist joint, aiming for better movement and stability at the wrist joint with preservation of longitudinal growth. The method uses preoperative soft tissue distraction to obtain proper alignment of the hand on the ulna before the second metatarsophalangeal joint with the whole metatarsal bone is transplanted. The treatment takes about 4 months and the optimum period for surgery is during the second year of life. Pollicization is added later in the normal manner. The new technique has been used in 12 cases by the author since 1987 and the results of the first nine cases are reported with a mean follow-up of 6 years. This technique appears to be promising but is demanding because of the microvascular joint transplantation at an early age.

Can quantitative 99mTc-MDP bone scans be used to predict longitudinal growth of epiphyseal plate allografts after microvascular transplantation? An experimental study

Allograft and autograft microvascular proximal tibial epiphyseal plate transplants were performed in female New Zealand White (NZW) rabbits to quantify the growth rate and total growth potential of immunosuppressed and nonimmunosuppressed rabbits. The purpose of this experiment is to examine whether the 99mTc-MDP radionuclide uptake of the transplanted epiphyseal plate at 1 week postoperatively, done to assess anastomotic patency of the transplant, could also serve as a predictor of eventual longitudinal growth of the transplant or replant. All transplants and replants demonstrating positive 99mTc-MDP uptake in the proximal tibial epiphyseal plate at 1 week showed continued longitudinal growth. The precise amount of 99mTc-MDP uptake, however, did not correlate with the amount of growth at 3 and 5 weeks follow-up.

Effect of ischemia and three different perfusion solutions on the rabbit epiphyseal growth plate

An isolated vascularized knee joint model was used (1) to determine the minimum ischemia time that produced growth retarding damage to the epiphyseal plate and (2) to evaluate whether intra-arterial perfusion could reduce the ischemia damage. Experiment 1 consisted of 31 rabbits in 5 groups: 0, 2,4,6, and 8 hr of warm ischemia produced by clamping the pedicle. Experiment 2 consisted of 18 rabbits in which 10 ml of one of (1) Euro-Collins, (2) University of Wisconsin solution, or (3) heparinized blood were perfused through the joint without ischemia. Experiment 3 consisted of 21 rabbits in which one of the three solutions was perfused for a short period during 6 hr of ischemia. Growth of the tibia was followed radiographically every month over 3 months, and the growth plates were evaluated histologically after sacrifice. Results showed that at least 6 hr of ischemia was needed before longitudinal growth was reduced; less ischemia time caused overgrowth. Histologic damage was found in all animals to some degree. Perfusion alone without ischemia had no detrimental effect on growth or histology. The growth reduction at 6 hr of ischemia was minimized by perfusion with every solution. Heparinized blood was the most effective and Euro-collins was the least effective.

Epiphyseal plate transplantation: an historical review

Non-vascularized and vascularized transplantation of epiphyseal plate autografts have been performed both clinically and experimentally for over 100 years. However, the ultimate clinical goal of vascularized transplantation of epiphyseal plate allografts for paediatric extremity reconstruction remains elusive, due primarily to the lack of suitably nontoxic techniques to prevent graft rejection. We have summarized the published clinical and experimental investigations of vascularized epiphyseal plate transplantation, and organized the experiments and clinical operations into four main groups: (1) local vascular studies on unmanipulated epiphyseal plates, (2) studies of epiphyseal plate behaviour after orthotopic replantation, (3) studies of epiphyseal plate behaviour after heterotopic transplantation, and (4) studies of epiphyseal plate behaviour after allograft transplantation. Prior investigations into the non-vascularized transplantation of epiphyseal plate autografts and allografts are presented as background. These groups of studies serve as the building blocks for the more clinically applicable experimental investigations outlined in the final section of this review.

Bernard O'Brien: the microsurgical transfer of immature bone

Bernard O'Brien was one of the pioneers of vascularized epiphyseal plate transfer. His clear understanding of the wide array of potential applications for reconstructive microsurgery stimulated his interest in the transfer of growing long bones. Investigations have been carried out in his laboratory since the earliest days of skeletal free tissue transfers. This paper describes the work done with epiphyseal plate transfers in O'Brien's laboratory. Research from other centers is then reviewed. Finally, the experience with clinical application is described.

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.

Short-term response of epiphyseal plate cell populations following selective devascularization and microsurgical revascularization

The distal femoral epiphyseal plates of 21 8-week-old New Zealand white rabbits were totally or partially (nutrient artery only) devascularized, or devascularized and then microsurgically revascularized. Sacrifice was at 24, 48 or 72 hours postoperatively. The heights of the proliferative and hypertrophic zones of the epiphyseal plates operated upon were compared with the contralateral control epiphyseal plates for both the central and the peripheral regions of the epiphyseal plate. Neither extent of devascularization nor revascularization had a significant effect on the height of the proliferative zone of chondrocytes at any of the follow-up intervals. Selective devascularization of the nutrient artery led to a significant increase in height of the central region of the hypertrophic zone of chondrocytes at 48 and 72 hours. Microsurgical revascularization did not lead to a significant change in the height of either the central or the peripheral regions of the hypertrophic zone of chondrocytes at any of the follow-up intervals. This study is another 'building block' experiment toward vascularized epiphyseal plate transplantation in humans.

Longitudinal growth after replantation of immature extremities on rats

Replantation of right hindlimbs in 76 immature rats was performed to study the factors affecting longitudinal growth of replanted extremities. There was a significant difference in tibia length between the replanted limb and the contralateral normal limb. The difference was significantly influenced by the ischemic interval (2 vs 4 hours), but not by suture method (intact vessels, vascular anastomosis with 10-0 nylon or 11-0 nylon). The replantation of immature extremities should be promptly undertaken because of the vulnerability of the epiphysis to ischemic insult.

Toe transfer for congenital hand defects

Toe-to-hand transfer is a well-established reconstructive option for certain congenital hand anomalies. It is the only technique which can add growth potential to the immature skeleton. Toe transfer is best suited for constriction ring amputations, which have relatively normal proximal anatomy. Transfers should be performed early in life to avoid lack of cortical integration of the new part. Anatomic variations of both hand and foot are often encountered, which influence both operative approach and functional prognosis. Indications, techniques, and complications are reviewed.

Free Vascularised Toe Joint Transfer for Reconstruction of the Metacarpo-Phalangeal Joint

Two single and two double free vascularised joint transfers from the foot to hand have been undertaken in four patients over a period of four years. All were to replace metacarpo-phalangeal joints in young patients in whom the use of prosthetic devices was considered unsuitable. All the transfers were successfully completed, but one failed late in the second post-operative week due to sepsis. The results of the remaining three transfers compare favourably with prosthetic arthroplasty and continue to improve. Donor site morbidity in the foot has been minimal and is reviewed.