Femoral strut allografts in cementless revision total hip arthroplasty

One hundred thirteen cases of cementless femoral revision total hip arthroplasty using either cortical strut or proximal calcar allografts were reviewed for radiographic incorporation at an average 4.75 years after operation. All cortical strut grafts were used to supplement the host bone after achieving stable femoral fixation by a tight distal diaphyseal fit. Eighty-seven of the 95 cortical strut grafts showed radiographic evidence of graft incorporation. Eleven of the 18 calcar grafts had resorbed. Complications consisted of eight dislocations, three pulmonary embolisms, two superficial infections, two myocardial infarctions, and two sciatic nerve palsies. When stable distal fixation of cementless femoral prostheses have been achieved, the cortical strut allograft can be readily incorporated into the host femur and augments the host bone structure.

Revision arthroplasty of the proximal femur using allograft bone

Revision arthroplasty of the hip may require restoration of bone stock on the femoral side to provide bone support for the new implant and restore anatomy and leg length. Large cortical defects can be reconstructed best with allograft bone because of the quality and quantity of the bone required. In this article, the surgical technique and results of cortical allograft as full circumferential and cortical strut grafts are presented.

Complications of proximal femoral allografts in revision total hip arthroplasty

Four revision hip arthroplasties using a well-described surgical construct involving a large frozen femoral allograft to replace a deficient proximal femur developed six major complications related to the use of the allograft or of the surgical construct. These cases represent three consecutive cases using this surgical construct performed by the senior author and one postoperative referral that used the same construct. The complications included three allograft fractures, two nonunions at the host-allograft junction, and one postoperative infection. All four of the patients previously had cemented revisions before the allograft procedure, and all had deficient proximal femurs at the time of the allograft procedure. All three of the fractures occurred at the tip of the femoral prosthesis within the allograft. The unacceptably high fracture rate, three of four, was associated with the allograft functioning as an unsupported load-bearing element in this study.

Biomechanical evaluation of interference screw fixation in a bovine patellar bone-tendon-bone autograft complex for anterior cruciate ligament reconstruction

A bovine model was developed for biomechanical evaluation of anterior cruciate ligament (ACL) reconstruction using patellar bone-tendon-bone (b-t-b) autograft to examine the differences in time zero fixation mechanical properties of different interference screw lengths and diameters. The surgical technique of interference screw fixation of the b-t-b complex performed clinically was reproduced in a controlled animal model. The femur-patellar tendon graft-tibia complex was tested with anterior displacement of the tibia in 30 degrees of knee flexion to allow examination of the femoral and tibial fixation properties simultaneously. The statistical model concurrently explored differences between screw length and diameter while accounting for variations between graft properties. No statistically significant differences were found between the 7- and 9-mm screws with respect to peak load or energy to failure when using a 10-mm triangular graft in a 10-mm tunnel. The 7- and 9-mm screws were superior to the 5.5-mm screws with respect to these same parameters. Based on our results, the 7-mm interference screws can be used with equal confidence as the 9-mm screw, and the 20-mm length can be similarly exchanged for 30-mm length for patellar b-t-b graft fixation.

Revision total hip arthroplasty. The use of solid allograft

Intact solid allograft was used to augment severe bone loss in 8 acetabula and 15 femora in 22 patients who underwent revision total hip arthroplasty with noncemented implants. The average follow-up period was 4 years. The average time to radiographic union of whole acetabular allografts was 11 months. Superior migration of the allografts occurred in four patients. Varus tilt of the acetabular component within the allografts was noted in three patients. Eleven patients underwent entire proximal femoral allograft reconstruction, and four patients had femoral head allograft reconstruction. Nine patients with entire proximal femoral allografts achieved radiographic union at an average of 13 months and two failed by nonunion. Only one of the four patients with femoral head allograft reconstruction achieved union. Femoral component subsidence was noted in seven whole proximal femoral allografts (64%). Entire proximal femoral allograft reconstruction was complicated by at least one episode of postoperative dislocation in 6 of 11 procedures. The authors recommend that femoral head allografts should be used with caution to reconstruct proximal femoral deficiencies in which structural support is required for stability of the implant. Successful use of acetabular allografts requires that the majority of the allograft be contiguous to host bone and not to soft tissue. With entire proximal femoral reconstruction, the tip of the femoral component should not reside at the host-graft junction. All components should be cemented into allograft bone; and revision surgery should be performed before osteolytic destruction of bone advances to the point where allograft reconstruction is required.

Roentgenographic procedure for selecting proximal femur allograft for use in revision arthroplasty

A roentgenographic scoring system was developed to help orthopaedic surgeons and bone banks estimate the quality of bone stock in proximal femoral allografts intended to use in revision arthroplasty. This system scores a standardized anteroposterior roentgenograph of the proximal femur using four indices representing morphological features of cancellous and cortical bone known to be clinically associated with bone strength. The indices were combined to give a weighted score, which was thought to reflect the ability of a bone to carry in vivo loads. Thirty bones were evaluated for bone mineral density using dual-photon absorptiometry. They were then sent to another institution and evaluated using the newly devised roentgenographic scoring system. The results showed that the bone score roentgenographic method is a reasonable technique for selecting allograft femurs for transplantation. This roentgenographic technique and scoring system has now been packaged into kits and is available to orthopaedic surgeons and bone banks for evaluating bone stock quality in proximal femoral allografts intended for transplantation.

Proximal femoral allografts in revision total hip arthroplasty

The senior authors have performed 141 proximal femoral whole-bone allografts in failed total hip reconstruction. The results of the first 50 have been previously reported. This study reviews 70 additional cases performed since 1987 and reflects improved technique and several different junctional constructs. Modest improvements in the rate of union (64% v 80%) and of dislocation (28% v 16%) have been achieved. The infection rate (6% v 4%) and demographics of the groups have remained constant. The frequency of complications (67% v 53%) has decreased, but unfortunately remains high. A step-out allograft junction with a long lateral sleeve has been the most reliable construct.

Techniques of bone grafting in total knee arthroplasty

Bone grafting of osseous defects in primary or secondary total knee arthroplasty remains a popular and often indispensable solution to reconstructive problems. Solutions to contained, uncontained, and massive defects of both the tibia and femur are presented, as well as several options for reconstruction of deficient or ruptured extensor mechanisms.

Biomechanical comparison of bone graft used in anterior spinal reconstruction. Freeze-dried demineralized femoral segments versus fresh fibular segments and tricortical iliac blocks in autopsy specimens

This study compares the compression strength of frozen corticocancellous iliac blocks and short fibular segments with freeze-dried, partially ("surface") demineralized microperforated (FDPDM) short femoral segments. Three blocks from each iliac crest and segments from the fibular and femoral diaphyses were retrieved. The femoral segments were microperforated, demineralized for 24 hours, and freeze-dried. All were then loaded to failure in a stress testing machine. The FDPDM showed a significantly higher failure load and stiffness than the fibular segments and the iliac crest segments. The femoral and fibular segments were similar in strength but significantly higher than iliac crest grafts. Compared with commonly used frozen grafts, freeze-dried partially demineralized femoral segments may be used safely as axial load-bearing struts in anterior spine reconstruction.

Vascularized bone autografts

Recent advances in microvascular surgery have made it possible to reconstruct large skeletal defects with autogenous bone grafts on a vascular pedicle. Experimental studies have demonstrated that vascularized bone grafts have superior blood flow and osteocyte survival when compared with nonvascular grafts. This improves the union rate and allows full incorporation of cortical bone, remodeling, and graft hypertrophy. Clinical experience over the past decade demonstrates that 80% to 90% of these grafts are ultimately successful, allowing limb salvage in complex reconstructive cases. However, the technique is technically demanding, has a relatively high complication rate, and requires prolonged immobilization and rehabilitation. Thus, vascularized bone grafts should only be used when simpler reconstructive techniques are unlikely to succeed.

Cortical strut allografts for femoral reconstruction in revision hip arthroplasty

One hundred thirty-six cortical strut allografts fixed to the femur in revision hip surgery were studied using quantitative and qualitative radiographic analysis. In addition, 58 patients were clinically evaluated. The grafts showed a consistent behavior characterized by some resorption, bony bridging between host and graft, and a high incidence of union. The grafts showed evidence of revascularization and in some cases complete incorporation. The average Harris scores in the clinical group increased from 48 to 79 and was not influenced by the quality of bone before revision. Strut allografting of the femur in revision surgery is a reliable method of augmenting bone stock.

Biomechanical assessment of surface demineralized micro-perforated femoral diaphyseal segmental allograft

The use of surface demineralized micro-perforated femoral allograft (SDMFA), in the form of short diaphyseal segments, is of interest for anterior thoracic and lumbar spine reconstruction. Its reported osteoinductive capacity is enhanced by demineralization, though the mechanical strength is reduced. The strength of SDMFA segments was significantly higher at 24 h of demineralization time as compared to 48 h of demineralization time. The SDMFA segments from the junction of the proximal and mid-third of the femoral diaphysis had the greatest load to failure and stiffness.

Femoral allograft reconstruction in revision total hip arthroplasty

Rigid graft fixation with cortical loading through the graft to protect from stress shielding is an important goal during femoral allograft reconstruction in revision total hip arthroplasty. Total proximal femur allografts require intramedullary prosthetic splinting and a step-cut osteotomy or extended lateral allograft plate for the most secure fixation and ultimate union. Nonunion and dislocation are the most critical complications, and infection rates are similar to other reconstruction procedures. This review discusses the principles and application of allografts in femoral revision total hip arthroplasty.

[Transmission electron microscopy observations of a homologous bone graft preserved at -196 degrees C]

The authors have studied the ultrastructural modifications after one year of a homologous bone grafting stored for 8 days in nitrogen liquid at -196 degrees C. It was observed that the osteocytes showed nuclear and cytoplasmic degenerations; the empty lacunae showed precipitates of mineralized matrix. In comparison with a bone autografting a homologous bone grafting lost the ability of bone synthesis.

Bone graft and total hip arthroplasty. A review

The success of total hip arthroplasty has been well documented. Aseptic loosening remains the major long-term problem that can lead to significant bone loss and structural deficits. Bone graft has been used with increasing frequency to reconstruct these difficult cases. In this review, the authors detail the biology, biomechanics, and banking of bone grafts. A summary of currently available data on the clinical result of autograft and allograft in reconstructive hip surgery is presented.

Vascularized bone allografts: an experimental study in dogs

This study attempted to re-establish vascularization to canine allograft bone by means of the introduction of a pedicle in the medullary canal with a capillary network. The experiment showed basically that the introduction of arteries and veins with a capillary network into the medullary canal of an allograft femur provided enough vascular supply to produce fibrous tissue and enough bone to cover preoperatively drilled holes, suggesting that the allograft "revives" with the introduction of a vascular supply.

[The dependence of the osteoinductive activity of the bone matrix on the mass and area of the transplant]

White rat experiments have demonstrated that bone matrix osteoinductive activity (the matrix ability to induce ectopic osteogenesis) is in direct proportion with the transplant mass in cases when this mass is within 0 to 0.16% b. m. A higher transplant mass is not associated with elevated osteoinductive activity. When the transplant masses are equal, their osteoinductive activities are in proportion with their sizes. These regularities should be borne in mind when choosing the transplant mass and shape.

Inhibition of the immune response to experimental fresh osteoarticular allografts

The immune response to osteoarticular allografts is capable of destroying the cartilage--a tissue that has antigens on its cells identical to those on the bone and marrow cells. Osteoarticular allografts of the distal femur were performed in rats using various methods to attempt to temporarily inhibit the antibody response. The temporary systemic immunosuppressant regimens investigated were cyclophosphamide, azathioprine and prednisolone, cyclosporine A, and total lymphoid irradiation. The most successful appeared to be cyclosporine A, but significant side effects were observed. To specifically inhibit the immune response in the allograft antigens without systemically inhibiting the entire immune system, passive enhancement and preadministration of donor blood were tried. Neither was as effective as coating the donor bone with biodegradable cements, a method previously found to be successful. Cyclosporine A was investigated in dogs in a preliminary study of medial compartmental knee allografts and was found to be successful in inhibiting the antibody response and in producing a more successful graft; however, some significant side effects were similarly observed.

Neuropathic arthropathy as a possible cause of failure of a whole joint allograft. A case report

This report illustrates the fate of a whole joint allograft in a 23-year-old male with chondrosarcoma of the right hip. An extraarticular resection of the right proximal femur and surrounding pelvis was performed. Reconstruction was carried out with a fresh-frozen cadaveric allograft of articulated proximal femur and acetabulum with the capsule intact. Excellent union at the junction of host bone with the allograft was demonstrated roentgenographically 12 months later. Nineteen months after the operation, as weight bearing proceeded, sudden onset of instability of the joint occurred without pain. Collapse of the allograft with partial dissolution of the femoral head and acetabulum were observed roentgenographically. Reconstruction was achieved with a prosthetic implant. The roentgenographic and pathologic features of the allograft are suggestive of neuropathic arthropathy; however, the possibility of allograft rejection cannot be excluded but seems unlikely.

[Preliminary results of 79 massive bone allografts in the conservative treatment of malignant tumors in adults and children]

We have used massive allografts, preserved by freezing to -30 degrees C and sterilised by irradiation, to reconstruct large defects in bone after resection of high grade neoplasms. The average length of the defect was 20.5 cm. Complications included 3 deep infections, 8 pseudoarthroses, of which 4 joined after further operation and 3 are still under treatment, and 4 late fractures of the graft. Seventy two cases have been followed up, and the functional result was excellent in 30, very good in 22, good in 13, poor in 3 and bad in 4. In 3 cases H.L.A. antibodies against the graft have been detected, but no clinical or radiological abnormality was noted. Bone scintigraphy showed progressive revascularisation of the graft from surrounding muscle. Reattachment of muscles to the allografts was successful, and contributed to the good functional results. Reconstruction with sterilised allografts, in association with long stemmed titanium prostheses or a cemented nail, gave a better functional results than using massive stainless steel prostheses in patients with a reasonable life expectancy.

Cement coating of osteoarticular allografts in rats to prevent the immune response

Recently, more attention is being paid to the treatment of the articular surface defect in the young, active individual. Resurfacing or "shell" allografts are being considered as one of the alternatives for treatment. The immune response by the host may be the chief obstacle to the successful use of fresh osteoarticular allografts. Since proteins on the surfaces of allograft bone cells are considered to be the principal antigens eliciting the immune response, we hypothesized that mechanical masking of these cells by a biodegradeable blocking agent might prevent the immune response. Osteoarticular allografts of the distal femur were performed in rats and the cut surfaces of the graft were coated with cement before implantation. In a preliminary experiment, six biodegradeable cement materials were tried (bone wax, zinc polycarboxylate, collodion, fibrin adhesive, zinc oxide, and isobutyl-cyanoacrylate). Of these, the zinc oxide cement and isobutyl-cyanoacrylate were effective in inhibiting the immune response observed in control rat distal femur allografts. A second experiment was performed using nine rats with zinc oxide and nine rats with isobutyl-cyanoacrylate cements. These were compared with 20 control rats that had allografts without cement coating. Eighteen of the control rats (90%) developed an immune response, while only 22% (2/9) of the rats with zinc oxide coating and 33% (3/9) of the rats with isobutylcyanoacrylate developed an immune response. In a third experiment distal femur allografts were performed in 13 rats using only the liquid component of the zinc oxide cement.(ABSTRACT TRUNCATED AT 250 WORDS)

Deep-freezing versus 4 degrees preservation of avascular osteocartilaginous shell allografts in rats

Osteocartilaginous allografts (distal femurs of rats) were stored at 4 degrees for six, 12, 24, and 48 hours and at -80 degrees for five days and then evaluated for viability of the bone and cartilage. Storage at 4 degrees for 12 or 24 hours had little effect on cartilage viability but decreased bone viability to 40% and 10% of controls, respectively. Storage at -80 degrees for five days resulted in nonviable bone in all cases but showed an either/or response of cartilage, with high viability in two cases and nonviability in the other eight cases. In a second set of experiments, femurs from rats were stored in situ at 4 degrees for 12 or 24 hours or were harvested and stored at -80 degrees for five days, after which they were transplanted into rats of a different strain. The antibody response to each set of femurs was measured at two, six, and 12 weeks after operation. The 4 degrees storage resulted in a moderately decreased immunogenicity, whereas the storage at -80 degrees resulted in significantly reduced immunogenicity.

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.