Limb preservation after wide resection of bone cancers can be managed by a variety of reconstructive methods. The use of a metallic megaprosthesis has been documented to provide benefits, including immediate cement fixation that allows full weight bearing and the potential for quicker recovery.1*4 The limitation of the megaprosthesis, especially in young patients, is the likelihood of eventual loosening or mechanical breakdown.
To improve the durability of the reconstruction, the allograft-prosthetic composite has been used to provide biointegration of the allograft to the host bone, resulting in functional load sharing with the large metallic implant.5 Additionally, the allograft allows for more reliable soft tissue reattachment and improved gait and function.6
Bone tumors also occur in the diaphyseal portions of the bone. After wide resection, defects are often reconstructed with an intercalary allograft. Intercalary allograft is usually composed of long pieces of bulk allograft fixed with intramedullary rods, derotation plates, and screws.
These reconstructions pose a unique challenge to orthopedic oncologists because of the difficulty in healing two allograft-host junctions. Fixation can be difficult, and nonunions and delayed unions are common. Bone grafting these junctions is often recommended to aid healing of the junction and incorporation of the allograft.
Allograft failure is reported to occur from infection (3%- 1 1 %), allograft fracture (1I%-19%), and nonunion at the allograft-host junction (4%-15%).7 Possible contributing factors to nonunion include bone/allograft apposition gaps >3 mm, early fracture of the graft, adjunctive chemotherapy or radiation, and loss of fixation.6
Apposition gaps between the host bone and allograft frequently fill in with fibrous tissue, preventing or delaying normal bone-to-allograft healing. For a patient to return to full function and activity, firm bridging of the allograft-host junction must be achieved. Most reports suggest the average time to heal an allograft-host junction is 12 months.5,7
This report focuses on a novel technique and early radiographic outcome using a periosteal replacement membrane to potentially aid in the repair of the allograft-host junction. The rationale for its use was to provide containment of graft material at the junctions.
In animal studies the unique biochemical and mechanical properties of periosteal replacement material have been demonstrated to provide a barrier to fibrous tissue ingrowth. The goal of this composite is to provide the ideal environment for healing of these difficult junctions.
MATERIALS AND METHODS
Between May 13, 2002, and November 27, 2002, nine patients from 13 clinics underwent primary or revision surgery after limb salvage procedures. All patients had a minimum 9week follow-up at the time of this report. Five men and four women were included in the study. The average patient age was 28 years (range: 1 1-48 years).
Figure 1. Graftjacket Acellular Periosteum Replacement Scaffold sutured into a tube-like structure.
Figure 2. Application of AlloMatrix Injectable Bone Graft Putty in Graftjacket configuration. Purse-string sutures were placed on either end of the Graftjacket construct.
Seven patients were treated for primary tumor resection, and two patients were treated for allograft/host bone nonunion. Three patients were treated with an intercalary allograft of the femur, two patients were treated with a proximal tibial allograft prosthetic composite (APC), two patients had a distal femoral APC, and two patients had a partial resection of the distal end of the femur with subsequent uncontained defects.
Each patient had allograft supplemented with demineralized bone and calcium sulfate (AlloMatrix Injectable Bone Graft Putty, Wright Medical Technology, Ine, Arlington, Tenn) mixed with bone marrow and encased by the periosteal graft (GraftJacket Acellular Periosteum Replacement Scaffold, Wright Medical Technology, Ine). Later procedures also incorporated AlloMatrix Custom Bone Graft Putty with donor-matched cancellous bone chips.
There were 10 allograft-host junctions and two uncontained defects. Diagnoses included four patients with osteosarcoma, one patient with a neurosarcoma of bone, one patient with a Ewing's sarcoma one patient with a chondromyxoid fibroma, and two patients with nonunions following an en bloc resection of sarcoma. Eight patients underwent postoperative chemotherapy immediately following the grafting procedure. One patient received radiation to the area at 8 weeks postoperative.
Radiographs were examined to determine the presence of graft material and bone repair at the junction site. Migration of the bone graft material, resorption, and progressive callus formation were assessed at each postoperative follow-up. AU patient complications were recorded.
Preoperative planning is essential for resection and reconstruction of bone tumors. The procurement of fresh frozen bulk allograft is carefully orchestrated with radiographic sizing techniques to ensure appropriate length, diameter, and type of allograft for the specific procedure.
All allograft used in this series was harvested and processed in accordance with the American Association of Tissue Bank guidelines. After visual inspection, each graft was thawed on the sterile field according to the instructions provided by the tissue supplier.
The intercalary allograft incorporated a femoral nail inserted into the premeasured allograft segment with unicortical derotation plates at the proximal and distal graft-host junctions to control rotation. The allograft-prosthetic composites consisted of a stem cemented into the precut allograft and press-fit into the host bone without a derotation plate.
Each allograft-host junction was treated with either one or two 5-mm X 10-mm pieces of GraftJacket Acellular Periosteum Replacement Scaffold carefully wrapped circumferentially around the junction to avoid the neurovascular bundle.
When two Graftjacket Acellular Periosteum Replacement Scaffolds were required to surround the junction, they were joined using polydioxanone sutures (PDS II, Ethicon, Ine, Somerville, NJ). A running suture was used to create a tubelike construct over the allograft-host junction (Figure 1). A purse-string was placed above and below the junction, and the membrane was filled with a composite of AlloMatrix Injectable Putty with or without AlloMatrix Custom Bone Putty and allograft cancellous chips reconstituted with bone marrow (Figure 2).
After the procedure, each patient was immobilized using an appropriate brace for 6 weeks and then began physical rehabilitation. Partial weight bearing began approximately 3 months postoperatively, and full weight bearing was permitted as tolerated at 6 months. Each patient was followed in the clinic at 3- to 6-week intervals, and radiographs were taken at each office visit.
Follow-up averaged 16 weeks (range: 9-34 weeks). Radiographs were taken of all patients immediately postoperatively to establish a baseline. The author analyzed the films to determine migration of the graft material, graft resorption, and progressive callus formation (Figure 3). The host-allograft junction was considered healed when a bridging hard callus with signs of stress-oriented trabaculae was evident.5
None of the sites exhibited migration of the graft. One patient, who was a heavy smoker, showed complete resorption without callus formation. However, this patient has gone on to exhibit radiographic healing as evidenced by progressive obliteration of the allograft-host junction and is asymptomatic. Both patients treated for nonunion of their allograft-host junctions have developed early bridging calluses with signs of progressive maturation. There were no perioperative complications. There was one event of wound drainage secondary to hematoma formation that resolved without sequela.
Complications remain with reconstruction of large en bloc resections of bone neoplasms with allograftprosthesis and intercalary composites. In addition to the concerns of infection, fracture, and early loosening, the problems of nonunion and delayed union must be addressed.
Poor vascularity, apposition gaps, fibrous ingrowth, postoperative chemotherapy, and radiation contribute to a significant incidence of nonunions or delayed unions. Fibrous ingrowth into the junction prevents or delays bone healing and solid union of the junction. In an effort to aid healing of these difficult junctions, local particulate bone graft is frequently used.
Particulate bone graft can be difficult to maintain in position at these junctions. In this review, an extracellular matrix was used as a graft containment device. GraftJacket Acellular Periosteum Replacement Scaffold has demonstrated the ability to provide a favorable microenvironment for bone repair by preserving the biochemical and extracellular structural properties of the dermal collagen structure, thereby providing a template to serve as a pathway for rapid revascularization and subsequent nutritional diffusion.
The extracellular matrix promotes tissue repopulation and aids in preventing fibrous tissue migration into the graft site. Fibrous ingrowth inhibits bone growth and solid union of the junction.
Figure 3. Nineteen-week postoperative AP (A) and lateral (B) radiographs of a distal junction of a femoral intercalary allograft. Note maturing callus.
In this study, the investigators at the clinic hoped to create an ideal environment to promote bone growth at the allograft-host junction and prevent fibrous ingrowth. Although the results are preliminary, they have been encouraging. Containment of the graft material occurred in all patients. Effects on time to bone healing and incidence of nonunion require additional follow-up.
1. Wilkins RM. Stringer EA. Demineralized cortical bone powder: use in grafting space-occupying lesions of bone. Orthop Inter Ed. 1994; 2:71.
2. Eckardt JJ. Kabo JM. Kelley CM. et al. Expandable endoprosthesis reconstruction in skeletally immature patients with tumors. Clin Orthop. 2000:373:51-61.
3. Schindler OS. Cannon SR, Briggs TW. Blunn GW. Grimer RJ, Walker PS. Use of extendable total femoral replacements in children with malignant bone tumors. Clin Orthop. 1998,357:157-170.
4. Wirganowicz PZ. Eckardt JJ, Dorey FJ, Eilber FR, Kabo JM. Etiology and results of tumor endoprosthesis revision surgery in 64 patients. Clin Orthop. 1999; 358:64-74.
5. Zehr RJ. Enneking WF, Scarborough MT. Allograft-prosthesis composite versus megaprosthesis in proximal femoral reconstruction. Clin Orthop. 1996; 322:207-223.
6. Fox EJ. Hau MA, Gebhardt MC, Hornicek FJ. Tomford WW, Mankin HJ. Longterm followup of proximal femoral allografts. Clin Orthop. 2002: 397:106-1 13.
7. Donati D. Giacomi ni S. Gozzi E. Mercuri M. Proximal femur reconstruction by an allograft prosthesis composite. CHn Orthop. 2002:394:192-200.