Effect of intramedullary polymethylmethacrylate and autogenous cancellous bone on healing of frozen segmental allografts

Cemented allograft-prosthesis composite reconstruction for the proximal femur tumor

INTRODUCTION

Cemented allograft-prosthesis composite (APC) reconstruction is one option following resection of the proximal femur tumor. However, rare studies have focused on the indications and complications. The goal of the present study was to (1) ascertain the indications for cemented APC arthroplasty in the proximal femur; (2) identify the detailed perioperative management; and (3) illustrate our experiences to avoid the complications of cemented APC.

MATERIALS AND METHODS

A total 28 patients who underwent cemented APC reconstruction of the proximal femur after tumor resection were retrospectively evaluated at a median follow-up of 56 months. Clinical records and radiographs were reviewed to evaluate patients' outcome.

RESULTS

In our series, excluding three cases of death that had a short follow-up period, union occurred in 22 (88.0%) patients (range 9-18 months). Nonunion of the greater trochanter was seen in six of the 12 patients (50.0%). Eight (32.0%) hips had resorption. There were two (8.0%) hips that were observed to have asymptomatic wear of the acetabulum. The average Musculoskeletal Tumor Society (MSTS) score was 26.5 points. The average Harris Hip Score (HHS) score was 80.6 points. There were no cases of recurrence, but metastasis was found in two hips.

CONCLUSIONS

Mastering indications, perioperative management, and complication prevention are all very important in the APC reconstruction after resection of the proximal femur.

Percutaneous lovastatin accelerates bone healing but is associated with periosseous soft tissue inflammation in a canine tibial osteotomy model

Experimental studies have shown the ability of statins to stimulate bone formation when delivered locally or in large oral doses, however most have been studied in rodents. This anabolic effect is through the selective activation of BMP-2. Our purpose was to determine the effects of local treatment with lovastatin on bone healing in mammals as a preclinical animal model. We administered lovastatin (6 mg/kg) by percutaneous injection to a canine tibial osteotomy stabilized with external fixation. We found that lovastatin improved bone healing after a single injection into the fracture site assessed by serial radiography and histology at bone union. However, lovastatin treatment resulted in adverse local soft tissue inflammation. These results suggest that percutaneous lovastatin injection may be a useful adjuvant treatment over the course of bone healing to augment fracture repair, although further investigation into the mechanism of soft tissue adverse effects is warranted.

Intercalary allograft reconstructions using a compressible intramedullary nail: a preliminary report

BACKGROUND

Although intercalary allograft reconstructions are commonly performed using intramedullary devices, they cannot generate compression across host-allograft junctions. Therefore, they sometimes are associated with gap formation and suboptimal healing conditions.

QUESTIONS/PURPOSES

We describe a new technique and present preliminary results for intercalary allograft reconstructions for tumors using a compressible intramedullary nail.

PATIENTS AND METHODS

We retrospectively reviewed 10 patients (19 host-allograft junctions) who underwent intercalary allograft reconstruction using the compression nailing technique. Two patients were excluded as they had additional vascularized fibular autografts, leaving 15 junctions in eight patients for analysis. Three of the intercalary reconstructions had supplemental plate fixation at one junction. All patients received host bone reamings and cancellous allograft and one had bone marrow aspirate and demineralized bone matrix in addition to the cancellous allograft. The minimum followup was 3 months (mean, 18 months; range, 3-39 months).

RESULTS

Thirteen of 15 junctions healed without additional surgery. Two diaphyseal-diaphyseal junctions did not unite after allograft arthrodeses. One patient underwent revision for nonunion 8 months after the initial procedure, with subsequent healing. The second patient had no evidence of union at 6 months, after which he was lost to followup. There were no allograft fractures or infections in any reconstruction. One patient died of metastatic renal cell carcinoma, and one patient had multicentric local soft tissue recurrences of a periosteal osteosarcoma requiring resection.

CONCLUSIONS

Our early observations indicate newer compressible intramedullary nails reliably address junctional gap formation, providing for a high rate of union while retaining the long-term benefits of intramedullary stabilization.

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Results of 32 allograft-prosthesis composite reconstructions of the proximal femur

The use of allograft-prosthesis composites for reconstruction after bone tumor resection at the proximal femur has generated considerable interest since the mid1980s on the basis that their use would improve function and survival, and restore bone stock. Although functional improvement has been documented, it is unknown whether these composites survive long periods and whether they restore bone stock. We therefore determined long-term allograft-prosthesis composite survival, identified major complications that led to revision, and determined whether allograft bone stock could be spared at the time of revision. We also compared the radiographic appearance of allografts sterilized by gamma radiation and fresh-frozen allografts. We retrospectively reviewed 32 patients with bone malignancy in the proximal femur who underwent reconstruction with a cemented allograft-prosthesis composite. The allograft-prosthesis composite was a primary reconstruction for 23 patients and a revision procedure for nine. The minimum followup was 2 months (median, 68 months; range, 2-232 months). The cumulative incidence of revision for any reason was 14% at 5 years (95% confidence interval, 1%-28%) and 19% at 10 years (95% confidence interval, 3%-34%). Nine patients (28%) had revision of the reconstruction during followup; four of these patients had revision surgery for infection. Allografts sterilized by gamma radiation showed worse resorption than fresh-frozen allografts. Based on reported results, allograft-composite prostheses do not appear to improve survival compared with megaprostheses.

LEVEL OF EVIDENCE

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

Allograft-prosthesis composites after bone tumor resection at the proximal tibia

The survival of irradiated allograft-prosthesis composites at the proximal tibia is mostly unknown. However, allograft-prosthesis composites have proved beneficial at other reconstruction sites. We presumed allograft-prosthesis composites at the proximal tibia would improve survival and facilitate reattachment of the extensor mechanism compared with that of conventional (megaprostheses) reconstructions. We retrospectively reviewed 26 patients who underwent resection of proximal tibia tumors followed by reconstruction with allo-graft-prosthesis composites. Patients received Guepar massive custom-made fully constrained prostheses. Allografts were sterilized with gamma radiation, and the stems were cemented into the allograft and host bone. The minimum followup was 6 months (median, 128 months; range, 6-195 months). Fourteen patients had one or more components removed. The median allograft-prosthesis composite survival was 102 months (95% confidence interval, 64.2-infinity). Of the 26 allografts, seven fractured, six showed signs of partial resorption, and six had infections develop. Seven allografts showed signs of fusion with the host bone. Six extensor mechanism reconstructions failed. Allograft-prosthesis composites sterilized by gamma radiation yielded poor results for proximal tibial reconstruction as complications and failures were common. We do not recommend irradiated allograft-prosthesis composites for proximal tibia reconstruction.

Gluteal muscle attachment during proximal femoral reconstruction in a canine model

In this 18 month in vivo canine study we compared three methods of attaching the gluteal muscles to the proximal femur during hip reconstruction with an allograft-prosthesis composite (APC). All three methods are commonly practiced in human hip revision surgery and data on their effectiveness in dogs is directly relevant to human treatment. The methods compared were host gluteal tendon sutured to allograft tendon, host greater trochanter apposed to allograft using a cable grip system, and host cortical bone shells around the allograft secured with cerclage wires. For each method, we assessed changes in allograft-host bone fusion, weight bearing, gluteal muscle mass, and structural properties through qualitative radiography, gait analysis, histology, and biomechanical testing. Hip reconstruction using the WRAP method resulted in the greatest limb use with complete resolution of gluteal muscle atrophy 18 months after surgery. This method yielded a stronger, more stable hip joint that allowed for more normal limb function. These hips had the more rapid rate of bony union at the host bone-allograft junction and little resorption of the graft. The increased limb use and resultant larger gluteal muscle mass conferred to the WRAP hip composites the greatest tensile strength and stiffness when tested 18 months after reconstruction. There was a large amount of new bone formation on the periosteal surface where the WRAP reconstructions had an overlay of live bone that resulted in a more rapid union and increased cortical width at the level of the osteotomy. New bone also penetrated into the allograft a greater distance from the osteotomy in the WRAP group.

Percutaneous injection of recombinant human bone morphogenetic protein-2 in a calcium phosphate paste accelerates healing of a canine tibial osteotomy

BACKGROUND

In this study, we evaluated the capacity of a single percutaneous injection of recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered in a rapidly resorbable calcium phosphate paste (alpha-BSM) to accelerate bone-healing in a canine tibial osteotomy model. We hypothesized that the osteotomy sites would heal faster after percutaneous delivery of rhBMP-2/alpha-BSM than they would after injection of alpha-BSM alone or after no treatment.

METHODS

Bilateral tibial osteotomy was performed and the sites were stabilized with external fixators in sixteen dogs. Four hours after the surgery, one limb of each dog was treated with a single percutaneous injection of rhBMP-2/alpha-BSM paste or an equal volume of alpha-BSM alone. There were eight limbs in each group, and the osteotomy site in the contralateral limb served as an untreated control. The results were evaluated with serial radiography and force-plate analysis at four and eight weeks after surgery and with mechanical testing and histologic examination at eight weeks after the surgery.

RESULTS

At four and eight weeks after the osteotomy and treatment, the scores for radiographic union were significantly greater for the rhBMP-2/alpha-BSM-treated limbs than they were for the alpha-BSM-treated or untreated, control limbs (p < 0.05). The callus area in the rhBMP-2/alpha-BSM-treated limbs was significantly greater than that in the alpha-BSM-treated and untreated, control limbs at four and eight weeks postinjection (p < 0.05). The time-integrated vertical force for the rhBMP-2-treated limbs was significantly greater than that for their contralateral controls at four weeks and significantly greater than that for the treated and control limbs of the alpha-BSM-treated dogs at four and eight weeks after the surgery (p </= 0.05). The rhBMP-2-treated limbs were significantly stiffer in bending and in torsion (p < 0.05) compared with the alpha-BSM-treated and control limbs. Histologic analysis demonstrated increased bone formation and more mature bone at the osteotomy site in the rhBMP-2-treated limbs compared with that in the alpha-BSM-treated and control limbs.

CONCLUSIONS

This study demonstrates the capacity of a single percutaneous injection of rhBMP-2 delivered in a resorbable calcium phosphate paste (alpha-BSM) four hours after surgery to accelerate the healing of tibial osteotomy sites in a canine model.

Allograft-allograft healing? Salvage of massive allografts after fracture

Two cases are presented in which an allograft was inserted to salvage a previous allograft bone reconstruction that had followed resection for osteosarcoma. In each instance an allograft-allograft junction was created and, with time, healed. In the first case, a fracture of a distal femoral osteoarticular allograft was salvaged by adding a second allograft and a total knee arthroplasty. This construct preserved the majority of the allograft and allowed rapid rehabilitation. In the second case, an allograft arthrodesis of the knee was salvaged after fracture by replacing the distal portion of the fractured allograft with a new allograft. Again, an allograft-allograft junction was created and healed within 6 months. Allograft fractures pose challenging reconstructive problems. In these two cases, the addition of more allograft facilitated continued limb salvage and function.