Massive bone allografts in large skeletal defects after tumor surgery: a clinical and microradiographic evaluation

Use of Three-dimensional Titanium Trusses for Arthrodesis Procedures in Foot and Ankle Surgery: A Retrospective Case Series

Periarticular osseous defects pose a challenge when considering arthrodesis. Failure to restore the cubic content of bone can result in shortening and malalignment, as well as subsequent biomechanical issues. This study reports on 12 patients treated with patient-specific 3-D printed (7) and prefabricated titanium trusses (5). Twelve consecutive patients were treated for osseous defects of the forefoot, hindfoot, and ankle with patient-specific, 3D printed or prefabricated manufacturer titanium trusses. Seven were customized, patient-specific 3D printed trusses (4WEB, Frisco, Texas) and 5 were prefabricated manufacturer titanium trusses. All patients had a minimum of 6 months of clinical and radiographic follow-up. and no patients were lost to follow-up. Seven of the 12 patients had a computed tomography (CT) scan performed following surgery. Successful limb or ray salvage was achieved in 11 of 12 patients (91.7%). Six of 7 patients (85.7%) with a postoperative CT scan, went on to complete radiographic consolidation across all arthrodesis sites. The remaining 5 patients showed complete consolidation across the arthrodesis sites on plain film radiographs. Complications included one patient with a residual midfoot deformity that required a subsequent midfoot osteotomy in order to obtain a plantigrade foot following successful tibiotalocalcaneal (TTC) arthrodesis, and a below knee amputation in one patient who underwent revision TTC arthrodesis to salvage avascular necrosis of the talus that developed following the index procedure. Eleven of 12 patients undergoing arthrodesis demonstrated successful union with both customized, patient-specific 3D printed and prefabricated manufacturer titanium trusses on CT scans or radiographs. The average follow-up was 14 months. Reports on traditional methods of addressing periarticular defects in patients requiring arthrodesis show mixed results and relatively high complication rates. Custom, 3D printed and prefabricated titanium truss technology offers an alternative to traditional methods for large, periarticular osseous defects.

Clinical applications of allografts in foot and ankle surgery

PURPOSE

The purpose of this review is to systematically analyse current literature on the use of allografts in the surgical treatment of foot and ankle disorders in adult patients. Based on this study, we propose evidence-based recommendations.

METHODS

The database for PubMed was searched for all published articles. No timeframe restrictions were applied. Clinical studies eligible for inclusion met the following criteria: performed on patients over 18 years old; subject to surgical treatment of foot and ankle disorders; with report on the outcome of the use of allografts; with a report and assessment of pain and function, or equivalent; minimum follow-up of 1 year was required. Two reviewers independently screened and selected studies for full-text analysis from title and abstract. 107 studies were included from 1113 records. Studies were grouped according to surgical indications into ten categories: musculoskeletal tumours (n = 16), chronic ankle instability (n = 15), ankle arthritis (n = 14), osteochondral lesions of the talus (n = 12), Achilles tendon defects (n = 11), other tendon defects (n = 9), fusions (n = 9), fractures (n = 8), hallux rigidus (n = 3) and other indications (n = 10).

RESULTS

Most studies displayed evidence level of IV (n = 57) and V (n = 39). There was one level I, one level II and nine level III studies. Most studies reported allografting as a good option (n = 99; 92.5%). Overall complication rate was 17% (n = 202).

CONCLUSIONS

Fair evidence (Grade B) was found in favour of the use of allografts in lateral ankle ligament reconstruction or treatment of intra-articular calcaneal fracture. Fair evidence (Grade B) was found against the use of allogeneic MSCs in tibiotalar fusions.

LEVEL OF EVIDENCE

V.

Tibiotalocalcaneal arthrodesis with distal tibial allograft for massive bone deficits in the ankle

BACKGROUND

The purpose of this study was to assess the outcomes of distal tibial structural allograft to obtain a stable TTC fusion.

METHODS

Retrospectively, ten patients were carried out with a minimum one year follow-up. The median age was 72 (33-81). The median BMI was 28 (24-33). Indications for TTC arthrodesis included failed total ankle arthroplasty (n=7 patients), prior nonunion (n=2 patients), and a trauma injury.

RESULTS

Union rate was 80%. The median initial height of the distal tibial allograft was 19mm (14-24mm). In seven cases the allograft did not lose height. The AOFAS score median was 69 (31-84). SF-12 median physical component was 39 (30-53), and 59 (23-62) for mental component. The VAS median was 2 (0-8).

CONCLUSIONS

TTC using distal tibial allograft shows a lower rate of collapse than other structural grafts and provides a fusion rate higher or in accordance with the literature.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Bone Regeneration after Treatment with Covering Materials Composed of Flax Fibers and Biodegradable Plastics: A Histological Study in Rats

The aim of this study was to examine the osteogenic potential of new flax covering materials. Bone defects were created on the skull of forty rats. Materials of pure PLA and PCL and their composites with flax fibers, genetically modified producing PHB (PLA-transgen, PCL-transgen) and unmodified (PLA-wt, PCL-wt), were inserted. The skulls were harvested after four weeks and subjected to histological examination. The percentage of bone regeneration by using PLA was less pronounced than after usage of pure PCL in comparison with controls. After treatment with PCL-transgen, a large amount of new formed bone could be found. In contrast, PCL-wt decreased significantly the bone regeneration, compared to the other tested groups. The bone covers made of pure PLA had substantially less influence on bone regeneration and the bone healing proceeded with a lot of connective tissue, whereas PLA-transgen and PLA-wt showed nearly comparable amount of new formed bone. Regarding the histological data, the hypothesis could be proposed that PCL and its composites have contributed to a higher quantity of the regenerated bone, compared to PLA. The histological studies showed comparable bone regeneration processes after treatment with tested covering materials, as well as in the untreated bone lesions.

Vancomycin iontophoresis of allograft bone

Objectives

The most concerning infection of allografts and operative procedures is methicillin resistant Staphylococcus aureus (MRSA) and no current iontophoresed antibiotics effectively combat this microbe. It was initially hypothesised that iontophoresis of vancomycin through bone would not be effective due to its large molecular size and lack of charge. The aim of this study was to determine whether this was a viable procedure and to find the optimum conditions for its use.

Methods

An iontophoresis cell was set up with varying concentrations of Vancomycin within the medulla of a section of sheep tibia, sealed from an external saline solution. The cell was run for varying times, Vancomycin concentrations and voltages, to gain information on optimisation of conditions for impregnating the graft. Each graft was then sectioned and dust ground from the exposed surface. The dust was serially washed to extract the Vancomycin and concentrations measured and plotted for all variables tested.

Results

Vancomycin was successfully delivered and impregnated to the graft using the iontophoresis technique. The first order fit to the whole data set gave a significant result (p = 0.0233), with a significant concentration (p = 0.02774) component. The time component was the next most significant (p = 0.0597), but did not exceed the 95% confidence level.

Conclusions

Iontophoresis is an effective method for delivering Vancomycin to allograft bone. The concentrations of the vancomycin solution affected the bone concentration, but results were highly variable. Further study should be done on the effectiveness of delivering different antibiotics using this method.

Long-term results of reconstruction with pelvic allografts after wide resection of pelvic sarcomas

Reconstruction after the resection of a pelvic tumor is a challenging procedure in orthopedic oncology. The main advantage of allograft reconstruction is restoration of the bony architecture of the complex pelvic region. However, high complication rates such as infection and allograft resorption had been reported in the literature. In this study, we aimed to retrospectively review nine patients treated with pelvic resection and structural pelvic allograft reconstruction. Functional results, complications, and survival of the patients and the allografts were evaluated. At a mean follow-up of 79 months, three patients were dead. Major complications were detected in eight of the nine patients. Infection (four of the nine patients) and allograft resorption (three of the nine patients) were the most common causes of failure. The cumulative survival of the patients was 66.7 percent at 70 months. However, allograft survival was only 26.7 percent at 60 months. Mean MSTS score was 69. In conclusion, we suggest that other reconstruction options should be preferred after pelvic resections because of the high complication rates associated with massive allograft reconstruction.

Tibiotalocalcaneal arthrodesis with bulk femoral head allograft for salvage of large defects in the ankle

BACKGROUND

Tibiotalocalcaneal arthrodesis in patients with large segmental bony defects presents a substantial challenge to successful reconstruction. These defects typically occur following failed total ankle replacement, avascular necrosis of the talus, trauma, osteomyelitis, Charcot, or failed reconstructive surgery. This study examined the outcomes of tibiotalocalcaneal (TTC) arthrodesis using bulk femoral head allograft to fill this defect.

METHODS

Thirty-two patients underwent TTC arthrodesis with bulk femoral head allograft. Patients who demonstrated radiographic union were contacted for SF-12 clinical scoring and repeat radiographs. Patients with asymptomatic nonunions were also contacted for SF-12 scoring alone. Preoperative, intraoperative, and postoperative factors were analyzed to determine positive predictors for successful fusion.

RESULTS

Sixteen patients healed their fusion (50% fusion rate). Diabetes mellitus was found to be the only predictive factor of outcome; all 9 patients with diabetes developed a nonunion. In this series, 19% of the patients went on to require a below-knee amputation.

CONCLUSIONS

Although the radiographic fusion rate was low, when the 7 patients who had an asymptomatic nonunion were combined with the radiographic union group, the overall rate of functional limb salvage rose to 71%. TTC arthrodesis using femoral head allograft should be considered a salvage procedure that is technically difficult and carries a high risk for complications. Patients with diabetes mellitus are at an especially high risk for nonunion.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Local delivery of FTY720 accelerates cranial allograft incorporation and bone formation

Endogenous stem cell recruitment to the site of skeletal injury is key to enhanced osseous remodeling and neovascularization. To this end, this study utilized a novel bone allograft coating of poly(lactic-co-glycolic acid) (PLAGA) to sustain the release of FTY720, a selective agonist for sphingosine 1-phosphate (S1P) receptors, from calvarial allografts. Uncoated allografts, vehicle-coated, low dose FTY720 in PLAGA (1:200 w:w) and high dose FTY720 in PLAGA (1:40) were implanted into critical size calvarial bone defects. The ability of local FTY720 delivery to promote angiogenesis, maximize osteoinductivity and improve allograft incorporation by recruitment of bone progenitor cells from surrounding soft tissues and microcirculation was evaluated. FTY720 bioactivity after encapsulation and release was confirmed with sphingosine kinase 2 assays. HPLC-MS quantified about 50% loaded FTY720 release of the total encapsulated drug (4.5 μg) after 5 days. Following 2 weeks of defect healing, FTY720 delivery led to statistically significant increases in bone volumes compared to controls, with total bone volume increases for uncoated, coated, low FTY720 and high FTY720 of 5.98, 3.38, 7.2 and 8.9 mm(3), respectively. The rate and extent of enhanced bone growth persisted through week 4 but, by week 8, increases in bone formation in FTY720 groups were no longer statistically significant. However, micro-computed tomography (microCT) of contrast enhanced vascular ingrowth (MICROFIL®) and histological analysis showed enhanced integration as well as directed bone growth in both high and low dose FTY720 groups compared to controls.

The enhancement of bone allograft incorporation by the local delivery of the sphingosine 1-phosphate receptor targeted drug FTY720

Poor vascularization coupled with mechanical instability is the leading cause of post-operative complications and poor functional prognosis of massive bone allografts. To address this limitation, we designed a novel continuous polymer coating system to provide sustained localized delivery of pharmacological agent, FTY720, a selective agonist for sphingosine 1-phosphate receptors, within massive tibial defects. In vitro drug release studies validated 64% loading efficiency with complete release of compound following 14 days. Mechanical evaluation following six weeks of healing suggested significant enhancement of mechanical stability in FTY720 treatment groups compared with unloaded controls. Furthermore, superior osseous integration across the host-graft interface, significant enhancement in smooth muscle cell investment, and reduction in leukocyte recruitment was evident in FTY720 treated groups compared with untreated groups. Using this approach, we can capitalize on the existing mechanical and biomaterial properties of devitalized bone, add a controllable delivery system while maintaining overall porous structure, and deliver a small molecule compound to constitutively target vascular remodeling, osseous remodeling, and minimize fibrous encapsulation within the allograft-host bone interface. Such results support continued evaluation of drug-eluting allografts as a viable strategy to improve functional outcome and long-term success of massive cortical allograft implants.

Reconstruction of the pelvis after resection of malignant bone tumours in children and adolescents

The predominant tumour of the pelvic region in children and adolescents is Ewing's sarcoma followed by osteosarcoma. Both tumours are treated by chemotherapy and the best chance of survival is offered by wide tumour resection. Compared to surgical treatment on the extremities, the resection and reconstruction of pelvic sarcomas remains challenging. Surgery of pelvic sarcomas shows higher rates of local recurrence and complications and a lower functional outcome than other localisations. Especially in children and adolescents the reconstruction methods have to focus additionally on the growing skeleton. According to the different types of pelvic resections and therefore the need of different reconstruction methods, the following article is based on Enneking's surgical classification of pelvic resections. Type I resections are best reconstructed with autografts implanted between the supracetabular osteotomy and the sacrum. Patients show the best functional results after this reconstruction. Periacetabular resections (type II) in small children do best with iliofemoral arthrodesis or pseudarthrosis; in larger adolescents the use of the pedestal Schoellner cup showed superior results over the prior saddle prosthesis. Type III resections are not reconstructed. Complete internal hemipelvectomy represents the most difficult situation, in children as well as in adults. High complication rates after allograft and endoprosthetic reconstruction have recently favoured the renaissance of a flail hip reconstruction or the hip transpositionplasty.

Inaccuracy in selection of massive bone allograft using template comparison method

The use of massive bone allografts is increasing year by year and selection method remains unchanged. Superposition of patient's radiograph over allograft image and comparison of distances is the gold standard. Experiment was led to test selection procedure of a major european tissue bank. Four observers were asked to select an allograft for 10 fictive recipients. Nine allografts were provided. To simulate a perfect allograft, recipient himself was inserted in the pool of allografts (trap graft). The 10 potential bone transplants were classified in four categories (from adequate to unacceptable). In addition, observers were asked to choose the three best grafts for a given recipient. Quadratic kappa measuring agreement on classification between two observers ranged between 0.74 (substantial) and 0.47 (moderate). Trap graft was quoted by observers as adequate four times (10%) and was cited eight times (20%) among the three best matching allografts. None of the observers discovered that recipient was among allograft panel. This study demonstrates that current selection method is inaccurate for hemipelvic allograft selection. New methods should be developed and tested to assist tissue banks in bone allograft selection.

Bone allografts: What they can offer and what they cannot

Bone allografts can be used in any kind of surgery involving bone from minor defects to major bone loss after tumour resection. This review describes the various types of bone grafts and the current knowledge on bone allografts, from procurement and preparation to implantation. The surgical conditions for optimising the incorporation of bone are outlined, and surgeon expectations from a bone allograft discussed.

Iontophoresis of antibiotics into segmental allografts

Iontophoresis is a novel technique which may be used to facilitate the movement of antibiotics into the substance of bone using an electrical potential applied externally. We have examined the rate of early infection in allografts following application of this technique in clinical practice. A total of 31 patients undergoing revision arthroplasty or surgery for limb salvage received 34 iontophoresed sequential allografts, of which 26 survived for a minimum of two years. The mean serum antibiotic levels after operation were low (gentamicin 0.37 mg/l (0.2 to 0.5); flucloxacillin 1 mg/l (0 to 1) and the levels in the drains were high (gentamicin 40 mg/l (2.5 to 131); flucloxacillin 17 mg/l (1 to 43). There were no early deep infections. Two late infections were presumed to be haemotogenous; 28 of the 34 allografts were retained. In 12 patients with pre-existing proven infection further infection has not occurred at a mean follow-up of 51 months (24 to 82).

Iontophoresis as a means of delivering antibiotics into allograft bone

Allograft bone is widely used in orthopaedic surgery, but peri-operative infection of the graft remains a common and disastrous complication. The efficacy of systemic prophylactic antibiotics is unproven, and since the graft is avascular it is likely that levels of antibiotic in the graft are low. Using an electrical potential to accelerate diffusion of antibiotics into allograft bone, high levels were achieved in specimens of both sheep and human allograft. In human bone these ranged from 187.1 mg/kg in endosteal (sd 15.7) to 124.6 (sd 46.2) in periosteal bone for gentamicin and 31.9 (sd 8.9) in endosteal and 2.9 (sd 1.1) in periosteal bone for flucloxacillin. The antibiotics remained active against bacteria in vitro after iontophoresis and continued to elute from the allograft for up to two weeks. Structural allograft can be supplemented directly with antibiotics using iontophoresis. The technique is simple and inexpensive and offers a potential means of reducing the rate of peri-operative infection in allograft surgery. Iontophoresis into allograft bone may also be applicable to other therapeutic compounds.

Treatment of giant cell tumors with allograft transplants: a 30-year study

We retrospectively reviewed 144 patients with giant cell tumors who had resection and implantation of cadaveric allografts from 1971-2001. Most procedures were done in the distal femur, proximal tibia, proximal femur, and proximal humerus. Seventy-eight percent of patients have retained their grafts and remain functional, but with limitations. Tumor complications included local recurrences (eight patients, none required an amputation) and metastases (three patients). None of the patients died. Allograft fracture occurred in 30 (21%) of the 144 patients, nonunion occurred in 12 (8%) patients, and infection occurred in 12 (8%) patients. Only patients with infection had a marked decline in outcome. Four patients required amputations, and only two of the eight patients with infection (17%) retained a functional graft. Eighty of the 144 patients (56%) had no complications, with a 94% success rate for the procedure. There have been fewer grafts done with the advent of burring, phenolization, and insertion of polymethylmethacrylate. However, based on our data and the good outcome for more extensive and destructive tumors, allograft implants can be used for treatment of patients with aggressive tumors, tumors that have caused fractures, or tumors that have recurred after conservative treatment.

Allograft arthrodesis of the knee in high-grade osteosarcoma

BACKGROUND

A retrospective cohort study was conducted to evaluate the outcomes of massive allograft arthrodesis in the management of high-grade osteosarcoma around the knee.

METHODS

The results of 19 patients with high-grade osteosarcoma around the knee, which was treated by wide resection and reconstruction using allograft arthrodesis, were evaluated for a mean length of 7.3 years (range, 3-13 years). The mean age at the time of surgery was 13.3 years (range, 6-27 years). According to the Musculoskeletal Tumor Society staging system, 17 patients were stage IIB and 2 were stage IIIB at presentation. Evaluations were based on the oncologic results, non-oncologic results and complications. Functional evaluation was performed with the Enneking functional evaluation form.

RESULTS

Four patients (21.1%) died of their disease; 3 (15.8%) are alive with disease; and 12 (63.2%) are free of disease. Four patients (21.1%) had local recurrence of their tumor at a mean of 23 months postoperatively (range, 9-44 months). The mean time to union of the metaphyseal junction was 24.7 weeks (range, 16-30 weeks) and the diaphyseal junction was 47 weeks (range, 24-78 weeks). The overall complication rate was 31.6%, including 2 (10.5%) infections, 3 (15.8%) allograft fractures, and 1 (5.3%) nonunion. Our mean final functional result was 65%.

CONCLUSION

Due to the high rate of complications in this study, we conclude that allograft arthrodesis should be left as a salvage or "back-up" reconstructive procedure after resection of osteosarcoma around the knee, unless there are special indications for this procedure. We found allograft fracture to be the most common complication.

Tissue banking in South Africa: a 19-year history

The establishment of a Tissue Bank and the science of Tissue Banking in South Africa started in the 1960s and is still developing. This article describes the development and growth of Tissue Banking in South Africa. The current emphasis is to supply viable bone products that have been produced under the best possible quality controlled circumstances; with the collaboration between different Organ Donation Organisations. Through collaboration, a dramatic increase in the number of donors was noted over the years. Concurrently, there was a dramatic increase in the usage of different allograft products and now necessitates the development of new graft materials for expanding patient options. As an ongoing concern, the Tissue Bank in South Africa experienced an ever increase in costs to enhance quality/safety controls: increase in historical patient information, documentation and serological testing in a population struggling to control HIV. To date, the South African Tissue Bank has not experienced any untoward patient incidence since the 1960s and currently is getting over 500 donors per year.

Large segment allograft survival is improved with intramedullary cement

BACKGROUND AND OBJECTIVES

The most common cause of failure in large segment bone allografts used for oncologic reconstruction is allograft fracture. Reinforcement with pressurized intramedullary cement may improve the mechanical properties of allografts.

METHODS

We reviewed the prospectively collected records of 45 patients who underwent en bloc resection of an extremity bone tumor and reconstruction using an allograft with intramedullary cement.

RESULTS

Seven allografts were used for arthrodesis, 20 were intercalary, and 18 were osteochondral. Twenty eight of 45 patients were alive at a mean 5.8 years (SD 1.9; range 3-11.2) with 24 allografts in situ. In these 45 patients, there were four allograft fractures and four infections. Six of these complications resulted in allograft removal. The estimated 5-year allograft survival rate was 86% (95% confidence interval 74-98%). Seven patients required secondary autogenous bone grafting for non-unions. Function measured by the Toronto Extremity Salvage Score and the 1987 and 1993 Musculoskeletal Tumor Society Rating Scales demonstrated a consistent pattern with worse function in patients with osteochondral allografts and best function with intercalary allografts.

CONCLUSIONS

These results suggest the addition of intramedullary cement to large segment bone allografts improves their survival by decreasing the fracture risk, particularly for allografts used for arthrodesis and intercalary reconstructions.

Allograft arthrodesis treatment of bone tumors: a two-center study

The current study consists of an outcome review of a consecutive series of 92 patients with knee arthrodesis using an allograft, done for malignant or aggressive tumors in two centers on different continents during a period of 18 years (mean followup, 5 +/- 4 years). The data were compiled by creating a computerized file using the information provided by both centers. Seventy-five of the patients (81%) had high-grade nonmetastatic tumors (Stage II), mostly osteosarcoma. In addition seven (8%) had metastases at outset (Stage III) and the remaining 10 (11%) had benign disease, mostly giant cell tumor or revision procedures for failed allograft or total joint replacement. Seventy-two patients (78%) had distal femoral lesions (78%) whereas the proximal tibia was the site of the tumor in 20 patients (22%). The average age of the patients was 23 +/- 16 years; 51 were males and 41 were females. Tumor complications were a major problem for patients in the series. Thirty-four percent of the patients died, 47% had metastases develop, and 9% had a local recurrence. Allograft complications included an infection rate of 20%, a fracture rate of 25%, and a nonunion rate of 44%. Repeat surgery was required for more than 50% of the patients with 26 requiring one additional operation, 11 requiring two, and 10 requiring three or more operations. Nineteen of the patients required an amputation (20%), only four of which were for recurrent tumor. When these data were compared with data for a control series of 880 patients with allografts other than allograft arthrodeses, the complications were greater and the outcome less successful, suggesting that other approaches should be considered unless there are special indications for this procedure.

Soft-tissue flap coverage maximizes limb salvage after allograft bone extremity reconstruction

Limb salvage after extremity tumor ablation may include the use of allograft bone. The primary complication of this method is infection of the allograft, which can lead to limb loss in up to 50 percent of cases. The purpose of this study is to evaluate the efficacy of primary muscle flap coverage in the setting of allograft bone limb salvage surgery. This study is a prospective review of all patients with flap coverage of extremity allografts over the 10-year period 1991 to 2001. There were 20 patients (11 male and nine female patients) with an average age of 28 years (range, 6 to 72 years). Flap coverage was primary in 16 patients and delayed in four. Delayed coverage was performed for failed wounds that did not have a primary soft-tissue flap. Pathologic findings included osteosarcoma in nine patients, Ewing sarcoma in five patients, malignant fibrohistiocytoma in two patients, chondrosarcoma in two patients, synovial sarcoma in one patient, and leiomyosarcoma in one patient. Allograft reconstruction was performed for the upper extremity in 12 patients and for the lower extremity in eight patients. Flap reconstruction was accomplished with 20 pedicle flaps in 17 patients (latissimus dorsi, 12; gastrocnemius, four; soleus, three; and fasciocutaneous flap, one) and four free flaps (rectus abdominis, three; latissimus dorsi, one) in four patients. All pedicled flaps survived. There was one flap failure in the entire series, which was a free rectus abdominis flap. This case resulted in the only limb loss noted. The follow-up period ranged from 1 to 50 months (average, 12.35 months). At the time of final follow-up, three patients were dead of disease and 17 were alive with intact extremities. The overall limb salvage rate in the setting of bone allograft and soft-tissue flap coverage was 95 percent (19 of 20). Reoperation for bone-related complications was required in 50 percent (two of four) of cases receiving delayed flap coverage compared with 19 percent (three of 16) of patients with primary flap coverage (statistically not significant). The results of this study support the use of soft-tissue flap coverage for allograft limb reconstruction. In this series, no limb was lost in the setting of a viable flap. Reoperation was markedly reduced in the setting of primary flap coverage. Pedicled or microvascular transfer of well-vascularized muscle can be used to wrap the allograft and minimize devastating wound complications potentially leading to loss of allograft and limb.

Perforations of cortical bone allografts improve their incorporation

The incorporation of perforated cortical bone allografts was compared with non-perforated allografts. A 5-cm circumferential defect in the middiaphysis at the tibia was created in adult sheep. A frozen tibial allograft was implanted and fixed with a locked nail for 6 months. There was no postoperative immobilization. Group I consisted of eight sheep with non-perforated allografts, whereas Group II was comprised of 10 sheep with perforated allografts. Union was evaluated radiographically, whereas the central part of the allograft had a densitometric evaluation. Creeping substitution was assessed on microradiographs from cross-sections of the central 3 cm of graft by measurement of porosity and percentage of new and old bone area within the confines of the graft. The width of periosteal and endosteal callus also was determined. There was no statistical difference between both groups for the union score and bone density. However, the cortical bone graft porosity and the amount of new bone within the cortical bone differed significantly between the perforated allografts and the non-perforated ones. Periosteal callus was similar in both groups, whereas endosteal callus was significantly more wide and extended in the perforated allografts. Perforation of a cortical bone substantially improved the amount of newly formed bone by the host when compared with a non-perforated bone. The creation of channels seemed to increase the interface between living soft tissues of the host and the allografted bone with a resulting enhanced incorporation.

Histomorphometric description of allograft bone remodeling and union in a canine segmental femoral defect model: a comparison of rhBMP-2, cancellous bone graft, and absorbable collagen sponge

The purpose of this study was to determine the effect of recombinant human bone morphogenetic protein type 2 (rhBMP-2) on the histomorphometry of femoral allograft-host bone union and allograft remodeling. A 6 cm mid-diaphyseal femoral defect was created and filled with an allograft stabilized with an interlocking nail in 21 dogs. Dogs were randomly divided into three equal groups and the allograft-host bone junctions and the mid-diaphyses of the allografts were treated with either an absorbable collagen sponge (ACS) loaded with rhBMP-2 (BMP group), an autogenous cancellous bone graft (CBG group), or ACS loaded with buffer solution (ACS group). All dogs received daily tetracycline until sacrifice at 24 weeks to label new bone formation. Histomorphometric analyses on sections of proximal and distal allograft-host bone junctions and the mid-diaphyseal portion of allografts were performed using fluorescent and regular light microscopy. Analyses of the host bone and junctions between allograft and host bone revealed significantly greater new bone formation and larger osteon radii in the BMP group compared to CBG and ACS groups and contralateral intact bone. Porosity in CBG and ACS groups was significantly higher than in the BMP group, which had similar values to intact bone. In transverse sections of allografts, the largest pore diameters were present in the CBG group. Based on all parameters measured, significantly higher bone turnover occurred in the outer cortical area of the allograft in all groups as compared to the inner cortical and mid-cortical areas. New bone formation and osteon radius/osteon width in allografts were similar for all three groups. Higher porosity and larger pore diameters in the CBG and ACS groups suggested higher bone resorption versus formation in these groups compared to the BMP group. The results of this study reveal more balanced allograft bone resorption and bone formation in the BMP group, with greater resorptive activity in the CBG and ACS groups. However, neither rhBMP-2 nor autogenous bone graft increased allograft incorporation when compared to the negative control (ACS group).

Bone bank service in Finland. Experience of bacteriologic, serologic and clinical results of the Turku Bone Bank 1972-1995

560 bones were harvested by The Turku Bone Bank between 1972-1995. It was started with massive allografts for bone tumor surgery, but today most are femoral heads for hip revision surgery. The increase in harvested bones nearly trebled from 1984-1989 to 1990-1995. Only 1 positive hepatitis C test was found. There were no hepatitis B or HIV positive donors. The incidence of discarding after screening was 24%, with positive bacterial growth (8%, usually Staphylococcus epidermidis) as the commonest reason. 2 massive grafts with negative cultures when harvesting were positive after thawing and resulted in deep infection. 369 allografts were transplanted. The infection rate of massive allografts for bone tumor surgery was 5/63 in 1973-1995, and 2/52 in 1985-1995. The infection rate for hip revision surgery was 3.4%. The clinical functional results correspond to those reported in larger international series.

The results of transplantation of intercalary allografts after resection of tumors. A long-term follow-up study

We reviewed the results of 104 intercalary allograft procedures that had been performed, between April 1974 and August 1992, in 100 patients, usually after resection of a segment of bone because of an osseous neoplasm. The median duration of follow-up was 5.6 years. Retention of the graft and return to essentially normal function were the measures of success and, on that basis, eighty-seven (84 per cent) of the 104 reconstructions were successful. Of the fifteen limbs in which the reconstruction failed, four were salvaged with insertion of a second allograft and three, with use of some other technique. Of the 104 allograft procedures, eight (including two in patients who had a recurrent tumor) were followed by an amputation; thus, the ultimate rate of salvage was 92 per cent for the entire series. Thirty-one grafts failed to unite at one junction with the host or both, within one year after the operation, and this necessitated eighty-one additional operative procedures to achieve a good result. Life-table regression analysis showed that age, gender, anatomical site, and length of the graft were not associated with significant differences in the over-all outcome. Infection (p = 0.0001); fracture (p = 0.002); stage of the lesion (p = 0.007); and use of adjuvant chemotherapy or radiation, or both (p = 0.008), all had an adverse effect on the survival of the allograft. Despite the relatively high rate of non-union that necessitated additional operations, these data indicate that transplantation of allografts for the treatment of intercalary defects has a high rate of success and usually results in a functional limb.

[Massive reconstruction of acetabulum and proximal femur]

In revision hip surgery, allografts are useful for restoring the bone stock and allow the muscle fixation avoiding the use of massive metallic prothesis.

MATERIAL AND METHODS

We have reviewed 51 hip reconstructions with a follow up of 4 years and half (1982 - 1991). Indications were: - revision arthroplasties with destroyed acetabulum, - bone tumors (mainly chondrosarcoma).

RESULTS

The results are good for pain, articular movement and the consolidation of the allograft host bone junction. Some complications were encountered: - Post-operative death (early or late for tumoral extension) in case of major surgery for tumor (4 cases). - Deep infections (2 cases). - Weakness of the gluteus medius with hip dislocation needing anti-dislocation device. - Aseptic serous fluid leak meaning immunobiologic reaction of bone grafts (3 cases).

DISCUSSION

This surgery has to be compared to massive reconstruction prostheses, arthrodesis with limb shortening, femoral head and neck resection and in some cases inter ilio-abdominal amputation which gives also major post-operative complication.

Long-term results of allograft replacement in the management of bone tumors

Over the past 24 years, the authors have implanted >870 massive frozen cadaveric allografts mostly for the treatment of defects created by the resection of a bone tumor. Most of the grafts were obtained from the authors' institutional bone bank. The results show that only stage and type of graft affected outcome predictably. Specifically, grafts for a Stage 2 or Stage 3 tumor had a poorer outcome than those for Stages 0 and 1. The results for allograft arthrodeses were considerably poorer than osteoarticular, intercalary, and allograft plus prosthesis. The other major factors in results were complications--recurrence, infection, fracture, and nonunion--with the former 2 having a profound negative effect on outcome. After the first year of susceptibility to infection (10%) and the third year of increased risk of fracture (19%), the grafts become stable, and approximately 75% are retained by patients and are considered to be successful for >20 years after implantation. Osteoarthritis becomes a problem at approximately 6 years for osteoarticular grafts, and so far, 16% of the patients with distal femoral, proximal tibial, or proximal femoral grafts have required total joint replacements. Although the current results are adequate, they are imperfect, and research should be directed at improving the results.

Follow-up of spongiosa plugs with contrast enhanced magnetic resonance imaging

The aim of this study was to evaluate the extent and duration of the revascularization process in spongiosa plugs when a fibrin sealant was used. 20 patients with tumour-like lesions, benign tumours and tumours with a potential for malignant transformation were studied. After intralesional tumour removal, the defect was filled with homologous spongiosa either combined with or without a fibrin sealant, according to a prospective randomization. Magnetic resonance imaging (MRI) follow-up examinations were performed within 1 week, and 1.5, 3, 4.5, 6, 8, 12, 24 and 36 months after surgery. Those patients without a fibrin sealant showed an increased revascularization zone up to the sixth week. Patients treated with fibrin, however, showed increased revascularization up to 3 months. In the 25% percentile the extent as well as the rate of revascularization is higher in those with a fibrin sealant. It is of clinical relevance that no revascularization should be expected at 3 months after surgery, which is easily demonstrated by MR follow-up.

Massive intercalary bone allografts in the treatment of primary and secondary bone tumors. A report on 21 cases

From 1981 to 1993, 21 patients received intercalary bone allografts for reconstruction of the extremity after en bloc tumor resection (15 malignant and 6 benign tumors). The allografts were collected from multiorgan donors and cryopreserved at -70 degrees C. The mean follow-up was 4.4 (range 1-13) years. The fate of the grafts was followed by conventional radiography, bone scintigraphy, and functional assessment. The overall survival rate of the 7 patients with high-grade malignancies was 86%. Solid union of the graft-host sites in less that 15 months occurred in 85%. An increased isotope uptake of the graft indicates that incorporation at the osteotomies as well as remodelling is still continuing at 9 years after operation. The overall complication rate was 43%; 3 patients had two or more complications. Complications were related to the allograft in 6 (infection or fatigue fracture in 1 and delayed healing in 4 cases) and to the osteosynthesis in 3 patients. The definitive results after treatment of complications show that satisfactory results have been obtained in all but 2 patients: 62% had excellent, 19% good, and 10% fair results. Intercalary allografts therefore provide a valuable solution for large skeletal defects after resection of bone tumors.

The effects of cisplatin on the incorporation of fresh syngeneic and frozen allogeneic cortical bone grafts

Allograft transplantation with concomitant chemotherapy has proven successful in the treatment of malignant bone tumors. However, these chemotherapeutic agents may delay tissue healing, resulting in clinical complications. To clarify the effects of cisplatin on the healing of bone grafts, we studied the incorporation of stably fixed massive diaphyseal femoral syngeneic and allogeneic grafts in rats treated with cisplatin. These data were compared with those of historical controls from animals that did not receive cisplatin. Rats that were to receive a fresh syngeneic graft or frozen allogeneic graft were given cisplatin every 4 weeks starting 9 weeks preoperatively and continuing until the time of death. The total bone area of the graft in animals that received cisplatin was smaller than that of the graft in untreated control rats that did not receive cisplatin. The area of the frozen allograft did not increase between 2 and 4 months. Revascularization was incomplete in cisplatin-treated groups at 2 months, but by 4 months, vessel ingrowth in fresh syngeneic grafts approached control values. Frozen allografts remained poorly revascularized at 4 months. Host-graft union was poor at 2 months in cisplatin-treated rats compared with controls. In cisplatin-treated rats, the host-graft union of the frozen allograft remained inferior at 4 months while that of the syngeneic graft improved. Allogeneic cortical bone grafts are incorporated more slowly and incompletely than syngeneic grafts, and this handicap is exacerbated by the administration of cisplatin.

Allograft in the treatment of benign cystic lesions of bone

Seventeen patients with benign cystic osseous lesions were treated by curettage and grafting using allogenic decalcified bone. Human bones were partially decalcified using 0.6 N HCl and preserved in 90% ethanol in a deep freezer at -16 degrees C. The cystic lesions were: 5 cases of fibrous dysplasia, 4 aneurysmal bone cysts, 3 simple bone cysts, 2 giant-cell tumours, 1 chondromyxoid fibroma, 1 non-ossifying fibroma and 1 fibrous cortical defect. The bones involved were: femur, tibia, humerus, fibula and calcaneum. Infection was a complication in three patients. In two of these it did not interfere with healing, but in one it persisted for more than 1 year with partial resorption of the graft. The time to adequate incorporation of the graft varied from 6 to 9 months in children and 9 to 15 months in adults. The overall response compares favourably with that to allograft from more sophisticated bone banks.

Current status of allografting for bone tumors

Over the past 20 years the Orthopaedic Oncology Unit of the Massachusetts General Hospital has performed over 660 massive cadaveric allograft transplantations, mostly for patients with bone tumors. The overall success rate for such procedures is around 80%, with most of the failures occurring in the first 3 years as a result of fracture (19%), nonunion (14%), and infection (10%). With longer follow up, late occurring osteoarthritis has been noted in approximately 17% of those patients at risk, suggesting that the articular surface begins to "wear" at 5 years. Some problems remain with the procedure, and more study of such aspects as the immune mechanism, cryopreservation of cartilage, maintaining the status and safety of the bone banking system, and improving the techniques of surgery ultimately may lead to a more uniform and predictable success rate.

Autogenously vascularised bone allografts. Experimental model of a new bone-muscle composite graft

Conventional bone allografts carry a high incidence of complications such as infections and pseudarthroses due to immunological rejection and avascularity of grafts. In vascularised grafts healing and remodelling of bone is quicker and more complete. However, vascularised allografts need immunosuppression for prevention of rejection with vascular occlusion. Autogenously vascularised allografts are formed after implantation of bone in muscle of the recipient, allowing vascularisation from this muscle. A muscle-bone composite graft is thus obtained that can be transferred as a pedicled or free graft with microvascular anastomosis. In this study donors were DA and recipients Lewis rats. The bone grafts were implanted in the adductor muscles and transferred after 6 weeks into a femoral defect. A higher number of osteocytes were found in the autogenously vascularised group than in non-vascularised grafts. "Creeping substitution" was found in all cortical layers in vascularised grafts, whereas in conventional allografts bone resorption predominated. The experimental data suggest that in rat autogenously vascularised bone allografts show a remodelling pattern comparable with that of conventional vascularised bone autografts. The advantage of the autogenously vascularised bone allograft is that it allows transfer of a vascularised bone allograft together with its well-vascularised recipient bed without immunosuppressive treatment.

Bone transplantation

According to one principle of surgery, the transplantation of vital tissue is the best method of reconstructing a defect. Because of absent immunologic reactions, high osteogenic potency, and preserved stability, transplantation of autogenous bone shows the best results. Necrosis of transplanted bone, leading inevitably to absorption and remodeling of the graft, can be avoided if microsurgically vascularized autogenous bone segments are transferred. Disadvantages are the low availability and the necessity of additional operations. As an alternative, deep-frozen allogeneic bone is used. However, this kind of bone shows delayed incorporation based on cellular and humoral immune reactions, and it is also installed into the host bed after overcoming the immune barrier. The risk of microbiological contamination or transmission of unrecognized germs such as HIV is a cause of great expense in bone banking techniques. If one succeeds in reducing (a) the immunologic defense reaction and (b) the risk of infection by sterilization or disinfection without damaging the osteoinductive proteins of bone matrix, the rate of complications can be lowered. Demineralized bone matrix can be used if biomechanical stability is not required. Its ability to induce osteogenesis without a major immune reaction or the risk of transmitting diseases justifies its clinical application. Further intensive research in these areas is unavoidable.