Freeze-dried allogeneic segmental cortical-bone grafts in dogs.

Forty-four adult male mongrel dogs were used to compare segmental cortical freeze-dried allogeneic bone grafts with fresh autogenous, freeze-dried autogenous, and fresh allogeneic segmental cortical grafts. Group I consisted of bilateral fresh autografts as external controls; Group II, a fresh autograft on one side for internal control and a freeze-dried autogenous graft on the other side to evaluate the effect of freeze-drying on repair; Group III, a fresh autograft on one side and a fresh allograft on the other side to measure the differences between autogenous and allogeneic grafts; and Group IV, a fresh autograft on one side and a freeze-dried allogeneic graft on the other to see if freeze-drying altered the repair of allogeneic grafts. The grafts were analyzed qualitatively over a six-month period by the use of interval roentgenograms to determine the times of graft-host union and the incidence of fatigue fractures. Six months after operation, the repair processes in the four groups were compared quantitatively with respect to biological repair and physical strength using torsional stress-testing, tetracycline labeling, and microradiography. The results indicate both qualitatively and quantitatively that: (1) fresh bilateral segmental cortical autografts show reproducible characteristics, so that the canine fibula furnishes a satisfactory model (Group I); (2) freeze-drying does not inhibit the repair process per se (Group II); (3) fresh allografts are rejected in varying degrees of intensity (Group III); and (4) freeze-drying does not protect cortical allogeneic grafts from such rejection (Group IV).     

Vertebral column allografts for the treatment of segmental spine defects. An experimental investigation in dogs

Vertebral column allografts, with their intervertebral discs, were implanted into thoracic spine defects (T7-T9) in 11 dogs in an attempt to re-establish spinal stability and preserve spinal biomechanics. Before implantation, the allografts were harvested under sterile conditions from similar-sized dogs and deep frozen at -80 C. The animals were followed for 18 months postoperatively. Radiographs demonstrated gradual loss of intervertebral disc height. Biomechanical analysis showed that the dogs with allografts had no significant difference in spine stiffness compared with normal spines in compression, flexion, and extension testing. Control spines that had been fused were significantly stiffer than the allograft spines in all modes tested (P less than 0.05). Histologic analysis showed incorporation of the allograft but with incomplete revascularization of the allograft's eighth thoracic body. This investigation found that vertebral body allografts with intervertebral discs can function successfully for 18 months in a canine model. This research may assist in the development of physiologic treatment for spinal deficiencies in humans.     

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).     

Surgical management of pilon fractures with large segmental bone defects using fibular strut allografts: a report of two cases

We present two patients with open pilon fractures with large bone defects treated successfully with fibular strut allografts. The patients were initially treated by massive irrigation, wound debridement, and temporary external fixation. After complete wound healing, the bone defects were managed. Because autologous iliac crest or fibular bone grafts were impossible to be harvested due to multiple fractures, the bone defects were reconstructed with fibular strut allografts. Fixation was performed with a periarticular distal tibia locking plate. At 2 months postoperatively, the patients ambulated with partial weight-bearing; at 6 months, they had full range of motion of the ankle joint and full weight-bearing.     

Iontophoresed segmental allografts in revision arthroplasty for infection

Revision arthroplasty after infection can often be complicated by both extensive bone loss and a relatively high rate of re-infection. Using allograft to address the bone loss in such patients is controversial because of the perceived risk of bacterial infection from the use of avascular graft material. We describe 12 two-stage revisions for infection in which segmental allografts were loaded with antibiotics using iontophoresis, a technique using an electrical potential to drive ionised antibiotics into cortical bone. Iontophoresis produced high levels of antibiotic in the allograft, which eluted into the surrounding tissues. We postulate that this offers protection from infection in the high-risk peri-operative period. None of the 12 patients who had two-stage revision with iontophoresed allografts had further infection after a mean period of 47 months (14 to 78).     

Bone allografts after segmental resection of tumours

Summary Massive cryo-preserved bone allografts were implanted in 17 patients after segmental resection, 10 for malignant and 7 for benign bone tumours. A segmental graft alone was used in 6 cases, a bone graft with an arthrodesis in 8, and a combination of graft and prosthesis in 1. The tumours were resected widely; the average length of graft was 6.4 cm in benign tumours and 11 cm in malignant tumours. Chemotherapy was given for one year after operation. There were 2 local recurrences, one severe infection, sloughing of the wound in 2, graft absorption in 3 and breakage of metal in 2. Follow up was from 14 months to 12 years. Bone healing was assessed by radiography in 13 cases. All grafted bone in patients receiving chemotherapy failed to heal primarily, as did 3 of the grafts for benign tumours. Secondary rigid fixation and an additional autogenous graft resulted in healing of the bone junction within a year.

---

Résumé Des allogreffes osseuses massives cryoconservées ont été mises en place chez 17 malades après résection segmentaire, 10 pour des tumeurs malignes et 7 pour des lésions bénignes. On a eu recours à une greffe segmentaire simple six fois, à une greffe avec arthrodèse huit fois et à l'association d'une greffe et d'une prothèse une fois. Les tumeurs ont été reséquées largement; la longueur moyenne des greffons était de 6,4 cm dans les tumeurs bénignes et de 11 cm dans les tumeurs malignes. La chimiothérapie a été poursuivie pendant un an après l'opération. On a observé deux récidives locales, une infection grave, deux nécroses cutanées, trois résorptions du greffon et deux ruptures du matériel métallique. Le recul est compris entre 14 mois et 12 ans. La guérison osseuse a été confirmée radiologiquement dans 13 cas. Aucune greffe osseuse n'a consolidé d'emblée chez les sujets soumis à une chimiothérapie, de même que dans trois tumeurs bénignes. L'emploi d'une fixation rigide et d'une autogreffe complémentaire a permis d'obtenir la consolidation de la jonction osseuse dans un délai d'un an.

     

Freeze-dried proximal femur allografts in revision total hip arthroplasty. A preliminary report

Failure of cemented total hip arthroplasty can emerge from several causes and may be associated with severe bone loss in the proximal femur with a marked diminution in functional capacity of the limb. This is a preliminary report of 14 patients with revision operations for failed total hip arthroplasty. Freeze-dried allograft bone ws implanted for restoration of extensive bone loss in the proximal for restoration of extensive bone loss in the proximal femur. All 14 patients were operated on to salvage failed cemented total hip arthroplasties. Allografts were employed only for large proximal femoral deficiencies. In these patients the alternatives were either an unstable excision arthroplasty or a femoral deficient prosthesis. After revision, all patients had complete bony union and ambulated with the assistance of a cane with greatly increased function and pain relief. There were no infection. Functionally, the patients have shown marked improvement. At this time there is no radiologic evidence of resorption of the graft. The use of bone allografts in this procedure has been encouraging to date; however, the follow-up period has been only 16-30 months. the success or failure of this procedure will be determined in time.     

Survival of massive allografts in segmental oncological bone defect reconstructions

Reconstructions of large segmental bone defects after resection of bone tumours with massive structural allografts have a high number of reported complications including fracture, infection and non-union. Our goal is to report the survival and complications of massive allografts in our patients. A total of 32 patients were evaluated for fracture, infection, non-union rate and survival of their massive allograft reconstructions. The average follow-up for this group was five years and three months. The total fracture rate was 13% with a total infection rate of 16%. We found a low union rate of 25%. The total survival of the allografts was 80.8% (± 18.7%) after five years. We found a five-year allograft survival of 80.8% which is comparable with other studies.

---

Résumé  La reconstruction des larges pertes de substances osseuses après la résection des tumeurs osseuses par des allogreffes structurales est pourvoyeuse d’un pourcentage élevé de complications, telles que fractures, infections et pseudarthroses. Le but de notre étude est de rapporter la courbe de survie et les complications de ces allogreffes massives. 32 patients ont été évalués en terme de fractures, d’infections et de pseudarthroses, après mise en place d’allogreffes massives, le suivi moyen du groupe a été de 5 ans et 3 mois. le taux de fractures est de 13%, le taux d’infections de 16%. Nous avons trouvé un taux relativement bas de consolidation 25%. La survie de ces allogreffes, globalement est de 80,8% (± 18,7%) après 5 ans. le taux de survie de ces allogreffes à plus de 5 ans est de 80,8%, il est comparable aux autres études.

     

Studies on segmental pancreatic autotransplants in dogs

Success with segmental pancreas transplants has been impaired by immunologic and technical considerations. Experiments were performed with autotransplants to avoid immunologic problems, allowing concentration on surgical techniques. Survival of splenic lobe pancreas autotransplants in pancreatectomized dogs was extended with relocation of the graft from the groin to the abdominal cavity and distal arteriovenous fistula to increase graft flow. Fibrosis of the graft occurred regardless of the method of duct treatment, latex (Neoprene) or Silastic injection or free intraperitoneal drainage. Hormonal responses in normoglycemic animals showed normal insulin levels (6 +/- 0.8 microU/mL) as compared with controls (5.4 +/- 0.9 microU/mL), while peak levels during arginine stimulation were higher in dogs with autotransplants (39.7 +/- 20 microU/mL) than in controls (15.1 +/- 1.9 microU/mL. Pancreatic polypeptide basal levels in animals with transplants were 42 +/- 2.2 pg/mL as compared with 256 +/- 28 pg/mL in controls, with no response to bombesin or protein meal stimulation. In this model, splenic lobe was capable of maintaining normoglycemia with avoidance of ketogenic amino acid patterns. Continuous fibrosis was the biggest threat to islet survival.     

Vascularized fibular grafts for the reconstruction of segmental tibial bone defects

Free vascularized fibular grafts were employed in seven patients with large tibial defects following trauma or resection of tumour. All patients were followed for more than 5 years. Tibial union and excellent functional results were achieved in all seven patients. Free vascularized fibular transfer seems to be an effective method of treatment for massive segmental bone defects.