Tibial stress fracture as a complication of free-fibula vascularised graft for mandibular reconstruction

Assessment of fibular regeneration after graft harvesting in patients with benign bone tumors: A retrospective study comparing different age groups

INTRODUCTION

Using non-vascularized fibula as autogenous graft has gained much success in reconstruction after tumor resection owing to its simplicity. Donor-site morbidity related to fibula deficiency includes valgus ankle, chronic pain and stress fractures of the ipsilateral tibia.

HYPOTHESIS

Growth potential before skeletal maturity is the most important factor promoting fibular regeneration after non- vascularized harvesting, and its decline with skeletal maturity causes failure of fibular regeneration.

PATIENTS AND METHODS

This is a retrospective study of the patients with benign bone tumors who required bone defect reconstruction by non-vascularized fibular graft utilizing a periosteal preserving technique. The study entailed 118 patients below the age of 12, 100 age 12-18, and 80 above the age of 18.

RESULTS

In children below 12, regeneration was complete in 95%, incomplete in 4.2% and partial in 0.8% of the cases. In adolescents, regeneration was complete in 72%, incomplete in 15% and partial in 13% of the cases. After skeletal maturity, no regeneration occurred in 92.5%of the patients, while partial regeneration occurred in 7.5% of the cases. Valgus ankle occurred in 2.8% of the cases before skeletal maturity, and none in older patients.

DISCUSSION

Complete regeneration after non-vascularized fibula graft harvesting is the rule in pediatric patients and to a lesser extent in adolescent group. This is usually associated by near normal regaining of the regenerate strength and function. Non-regeneration dominates in older age group. The length of the harvested segment has no impact on the regeneration or the remodeling process.

LEVEL OF EVIDENCE

IV; case series, retrospective comparative study.

Delayed pathologic tibial fracture with chronic osteomyelitis after fibula free flap

The reported donor site morbidity of the fibula free flap (FFF) is low; however, several uncommon complications have been reported with tibia fracture rarely being reported. We present a case of a pathological tibial fracture in the setting of chronic osteomyelitis after FFF. A 54-year-old female presented with a benign fibro-osseous lesion of the right mandible and was treated with mandibulectomy and reconstructed with a left FFF. Approximately 1 year following surgery, the patient presented to the emergency department. Imaging showed a pathological fracture of the distal third of the tibial shaft with persistent erythema and cellulitis of the lateral prior graft harvest site without signs of systemic infection. She was taken to the operating room for irrigation and debridement with culture and biopsy as well as external fixation of the tibial fracture. Intraoperative biopsy and culture demonstrated fracture site change with callus formation and negative culture. The patient was discharged on 6 weeks of IV vancomycin and ceftriaxone. In conclusion, tibial fracture following FFF is an uncommon complication, yet it can be exacerbated by chronic osteomyelitis. This report highlights the importance of close observation and comprehensive wound care of donor sites after free flap harvest for head and neck reconstruction.

Distal tibial fractures are a poorly recognised complication with fibula free flaps

The fibula free flap is ideal for complex jaw reconstructions, with low reported donor and flap morbidity. We discuss a distal tibial stress fracture two months following a vascularised fibula free flap procedure. Despite being an unrecognised complication, a literature review produced 13 previous cases; only two were reported in the reconstructive surgery literature, with the most recent claiming to be the first. The majority of these studies treated this fracture non-operatively; none reported their patient follow-up. Each case presented with ipsilateral leg pain, which has been cited as an early donor site morbidity in as many as 40% of fibula free flap cases. It is known that the fibula absorbs at least 15% of leg load on weight bearing. Studies have shown severe valgus deformities in up to 25% of patients with fibulectomies. We treated our patient operatively, first correcting his worsening valgus deformity with an external fixator, then reinforcing his healed fracture with a long distal tibial plate. We believe that this complication is underreported, unexpected and not mentioned during the consenting process. By highlighting the management of our case and the literature, we aim to increase awareness (and thus further reporting and appropriate management) of this debilitating complication.

Construction and characterization of a recombinant human adenovirus vector expressing bone morphogenetic protein 2

The aim of this study was to construct and characterize a novel recombinant human adenovirus vector expressing bone morphogenetic protein 2 (BMP2) and green fluorescent protein (GFP). The BMP2 gene in the plasmid pcDNA3-BMP2 was sequenced and the restriction enzyme recognition sites were analyzed. Following mutagenesis using polymerase chain reaction (PCR), the gene sequence after the translation termination codon was removed and new restriction sites were added. The mutated BMP2 gene (BMP2⁺ gene) was cloned into an adenovirus shuttle vector to obtain pShuttle cytomegalovirus (CMV)-BMP2⁺-internal ribosome entry site (IRES)-hrGFP-1. The adenovirus plasmid pAd CMV-BMP2⁺-IRES-hrGFP-1 was constructed by homologous recombination and was transfected into HEK293A cells, followed by adenovirus packaging. pAd CMV-BMP2 was used as the control. The two types of adenovirus were transfected into marrow stromal cells (MSCs). The expression of BMP2 and GFP, as well as the alkaline phosphatase (ALP) activity of expressed BMP2 were detected. Following mutagenesis, the BMP2 gene sequence and recombinant adenovirus vector were as predicted. The novel adenovirus vector expressed both BMP2 and GFP, indicating that a novel recombinant human adenovirus vector expressing BMP2 had been successfully constructed.

Near-infrared imaging of face transplants: are both pedicles necessary?

BACKGROUND

Facial transplantation is a complex procedure that corrects severe facial defects due to traumas, burns, and congenital disorders. Although face transplantation has been successfully performed clinically, potential risks include tissue ischemia and necrosis. The vascular supply is typically based on the bilateral neck vessels. As it remains unclear whether perfusion can be based off a single pedicle, this study was designed to assess perfusion patterns of facial transplant allografts using near-infrared (NIR) fluorescence imaging.

METHODS

Upper facial composite tissue allotransplants were created using both carotid artery and external jugular vein pedicles in Yorkshire pigs. A flap validation model was created in n = 2 pigs and a clamp occlusion model was performed in n = 3 pigs. In the clamp occlusion models, sequential clamping of the vessels was performed to assess perfusion. Animals were injected with indocyanine green and imaged with NIR fluorescence. Quantitative metrics were assessed based on fluorescence intensity.

RESULTS

With NIR imaging, arterial perforators emitted fluorescence indicating perfusion along the surface of the skin. Isolated clamping of one vascular pedicle showed successful perfusion across the midline based on NIR fluorescence imaging. This perfusion extended into the facial allograft within 60 s and perfused the entire contralateral side within 5 min.

CONCLUSIONS

Determination of vascular perfusion is important in microsurgical constructs as complications can lead to flap loss. It is still unclear if facial transplants require both pedicles. This initial pilot study using intraoperative NIR fluorescence imaging suggests that facial flap models can be adequately perfused from a single pedicle.

The outcome of pelvic reconstruction with non-vascularised fibular grafts after resection of bone tumours

We retrospectively evaluated 18 patients with a mean age of 37.3 years (14 to 72) who had undergone pelvic reconstruction stabilised with a non-vascularised fibular graft after resection of a primary bone tumour. The mean follow-up was 10.14 years (2.4 to 15.7). The mean Musculoskeletal Tumor Society Score was 76.5% (50% to 100%). Primary union was achieved in the majority of reconstructions within a mean of 22.9 weeks (7 to 60.6). The three patients with delayed or nonunion all received additional therapy (chemotherapy/radiation) (p = 0.0162). The complication rate was comparable to that of other techniques described in the literature. Non-vascularised fibular transfer to the pelvis is a simpler, cheaper and quicker procedure than other currently described techniques. It is a biological reconstruction with good results and a relatively low donor site complication rate. However, adjuvant therapy can negatively affect the outcome of such grafts.

A novel biomimetic polymer scaffold design enhances bone ingrowth

There has been recent interest in treating large bone defects with polymer scaffolds because current modalities such as autographs and allographs have limitations. Additionally, polymer scaffolds are utilized in tissue engineering applications to implant and anchor tissues in place, promoting integration with surrounding native tissue. In both applications, rapid and increased bone growth is crucial to the success of the implant. Recent studies have shown that mimicking native bone tissue morphology leads to increased osteoblastic phenotype and more rapid mineralization. The purpose of this study was to compare bone ingrowth into polymer scaffolds created with a biomimetic porous architecture to those with a simple porous design. The biomimetic architecture was designed from the inverse structure of native trabecular bone and manufactured using solid free form fabrication. Histology and muCT analysis demonstrated a 500-600% increase in bone growth into and adjacent to the biomimetic scaffold at five months post-op. This is in agreement with previous studies in which biomimetic approaches accelerated bone formation. It also supports the applicability of polymer scaffolds for the treatment of large tissue defects when implanting tissue-engineering constructs. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.

Donor-site complications of autogenous nonvascularized fibula strut graft harvest for anterior cervical corpectomy and fusion surgery: experience with 163 consecutive cases

BACKGROUND CONTEXT

The fibula is a source of bone graft for reconstruction of the appendicular and axial skeleton.

PURPOSE

The aim of this study is to determine donor-site complications and morbidity in a large series of patients who underwent autogenous fibula harvesting for anterior cervical corpectomy and fusion (ACCF) surgery.

STUDY DESIGN/SETTING

Retrospective review (Level III).

PATIENT SAMPLE

One hundred sixty-three patients over an eight-year period who underwent ACCF with autogenous fibula.

OUTCOME MEASURES

Donor site complications (such as infection, cellulitis, pain, damage to the superficial peroneal nerve, ankle instability, tibial stress fracture, and so forth), treatment, and final outcome were determined from patient records.

METHODS

Retrospective study of patients who underwent ACCF with autogenous nonvascularized fibula strut graft over an eight-year period (from 1995 to 2002) was conducted. Donor site complications (such as infection, cellulitis, pain, damage to the superficial peroneal nerve, ankle instability, tibial stress fracture, and so forth), treatment, and final outcome were determined from patient records.

RESULTS

One hundred sixty-three patients underwent ACCF with autogenous fibula graft during the study period. The most common short-term complication (lasting <3 months) was incisional pain, present in 86 of 163 patients (53%). Incisional pain lasted longer than 3 months in 25 of 163 patients (15%) but resolved in all but two patients by 24 months. Two patients (1.2%) developed superficial peroneal neuromas. Five patients (3%) developed tibial stress fractures. Two patients (1.2%) developed ankle instability. Fifteen (9%) patients developed cellulitis that resolved in all patients after a short course of oral antibiotics, with one additional patient developing a deep infection requiring surgical debridement and intravenous antibiotics.

CONCLUSIONS

Although autogenous fibula is an excellent graft for multilevel ACCF reconstruction, surgeons should carefully consider the associated morbidity of fibular harvest before surgery. In this series, most complications were of short duration. However, nine patients with long-term complications required five additional surgical procedures. Therefore, patients who are scheduled to undergo autogenous fibula harvest should be advised about these potential complications.

Free vascularized fibular transfer for femoral head osteonecrosis: donor and graft site morbidity

BACKGROUND

Autogenous vascularized fibular transfer is used effectively for a variety of complex reconstructive procedures. Published series demonstrating the morbidity associated with its harvest have, understandably, been relatively small, and graft site (hip) complications have not been reported. This report describes both the donor and the graft site morbidity associated with use of vascularized fibular transfer to treat osteonecrosis of the femoral head.

METHODS

Between 1990 and 2006, 1270 free vascularized fibular grafts were used to treat osteonecrosis of the femoral head in 946 consecutive patients. All procedures and follow-up examinations were performed by one of two surgeons. Subjective and objective findings were recorded on standardized examination sheets at routine postoperative intervals. Data were analyzed to determine the morbidity associated with donor and graft sites.

RESULTS

There were 215 complications (a 16.9% rate) at the time of follow-up, at an average of 8.3 years, after the 1270 procedures. Of these complications, 146 (11.5%) and sixty-nine (5.4%) were referable to the donor and graft sites, respectively. A major complication requiring an additional surgical procedure or chronic pain management occurred after fifty-four (4.3%) of the 1270 procedures.

CONCLUSIONS

A measurable but acceptable morbidity risk is associated with vascularized fibular transfer for the treatment of osteonecrosis of the hip. Major complications are not frequent, and many minor complications are transient and improve over time. Risks can be minimized when specific technical principles are followed.

Tibia adaptation after fibula harvesting: an in vivo quantitative study

Absence of the fibula after harvesting to reconstruct an upper-limb segment increases loads on the donor-side tibia and thereby provides a unique opportunity to analyze the bone adaptation process in humans. We therefore quantified densitometric and morphologic changes of the donor-side tibia in three young patients (ages 8, 13, 16 years), on the basis of computed tomography (CT) examinations of both legs (one preoperatively and two postoperatively). The range of final followup was 27-43 months. Three-dimensional models of shank bones were generated from CT data and used to measure cross-sectional area, diaphyseal cortical thickness, and cross-sectional moment of inertia. In addition, density of the newly formed bone was evaluated. The donor-side tibia showed morphologic and density adaptation with time. New bone was deposited predominantly in the interosseous space and almost replaced the bone area lost by excision of the fibula. The second moment of area grew more in the donor-side tibia than in the intact one, without fully recovering the contralateral tibia-fibula complex values, and the principal axes rotated toward the preoperative direction. Thus, while considerable adaptation had occurred by 27-43 months in these young patients, the adaptation was incomplete; the mineral density of the newly formed bone recovered normal cortical bone values only in the patient with the longest followup (43 months).

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

A heterotopic primate model for facial composite tissue transplantation

The purpose of this study was to develop a nonhuman primate model for heterotopic composite tissue facial transplantation in which to study the natural history of facial transplantation and evaluate immunosuppressive regimens.A composite oromandibular facial segment transplant based on the common carotid artery was evaluated. Flaps from 7 cynomolgus monkeys were transplanted to the groins of 7 recipients at the superficial femoral artery and vein. The immunosuppressive regimen consisted of thymoglobulin, rapamycin, and tacrolimus. Allograft survival ranged from 6 to 129 days. Histology performed in the long-term survivor at the time of necropsy revealed extensive inflammation and necrosis of the allograft skin; however, muscle and bone elements were viable, with minimal inflammation. This heterotopic facial transplantation model avoids the potential morbidity of mandibular resection and orthotopic facial transplantation. Our work also concurs with the work of other groups who found that the skin component is the most antigenic.

Review: Mineralization of Synthetic Polymer Scaffolds for Bone Tissue Engineering

It has repeatedly been shown that demineralization improves the ability of bone auto- and allografts to regenerate natural bone tissue. Conversely, much work in the field of bone tissue engineering has used composite materials consisting of a mineralized phase or materials designed to mineralize rapidly in situ. In this review, we seek to examine these disparate roles of mineralization and the underlying factors that cause this discordance and to examine methods and principles of the mineralization of synthetic polymer scaffolds. Biomimetic approaches to mineralization and phosphorus-containing materials are highlighted, and a brief section focusing on drug-delivery strategies using mineralized scaffolds is included.

Reconstruction with non-vascularised fibular grafts after resection of bone tumours

We evaluated 31 patients who were treated with a non-vascularised fibular graft after resection of primary musculoskeletal tumours, with a median follow-up of 5.6 years (3 to 26.7 years). Primary union was achieved in 89% (41 of 46) of the grafts in a median period of 24 weeks. All 25 grafts in 18 patients without additional chemotheraphy and/or radiotherapy achieved primary union, compared with 16 of the 21 grafts (76%; 13 patients) with additional therapy (p = 0.017). Radiographs showed an increase in diameter in 70% (59) of the grafts. There were seven fatigue fractures in six patients, but only two needed treatment.

Non-vascularised fibular transfer is a simpler, less expensive and a shorter procedure than the use of vascularised grafts and allows remodelling of the fibula at the donor site. It is a biological reconstruction with good long-term results, and a relatively low donor site complication rate of 16%.

Sex differences in long bone fatigue using a rat model

Stress fractures can occur because of prolonged exercise and are associated with cyclic loading. Fatigue is the accumulated damage that results from cyclic loading and bone fatigue damage is of special concern for athletes and army recruits. Existing literature shows that the rates of stress fracture for female athletes and female army recruits are higher than their male counterparts. In this study, we used an ex vivo rat model to investigate the fatigue response of female and male bones. We determined the strain versus number of cycles to failure (S/N) for each sex and found that for a certain initial strain (5,000-7,000 microepsilon) female bones have shorter fatigue life. To further characterize the bone response to fatigue, we also determined the creep that occurred during the fatigue test. From the creep data, for a certain strain range, female bones accumulated greater residual strains and reached the critical strain at a faster rate. In summary, this study demonstrates that female rat bones have a lower resistance to fatigue in the absence of a physiological response such as muscle fatigue or osteogenic adaptation. From these results, we hypothesized that creep was the underlying mechanism that accounted for the fast deterioration of female bones during fatigue.