Cement augmentation of the acetabulum for revision total hip arthroplasty for infection.

Antibiotic-loaded cement spacers in first-stage revision hip arthroplasty for infection are associated with a high dislocation and fracture rate. This technical note describes a novel surgical technique, utilizing screws and cement, improving acetabular coverage and reducing the risk of mechanical failure. Fifteen infected hip prostheses underwent removal, cement acetabular augmentation and insertion of a femoral cement spacer. Eleven hips had successful infection eradication and subsequently underwent a second stage revision procedure a mean duration of 15 weeks (9-48) after the first stage. No dislocations or fractures of the cement spacers were observed. This technique affords the potential to reduce the duration of time cement spacers remaining in situ, provides enhanced mechanical stability and improved antibiotic elution through cement-on-cement articulation.

Long-term results of fresh osteochondral allografts and realignment osteotomy for cartilage repair in the knee.

AIMS: The aim of this study was to report the outcome of femoral condylar fresh osteochondral allografts (FOCA) with concomitant realignment osteotomy with a focus on graft survivorship, complications, reoperation, and function. PATIENTS AND METHODS: We identified 60 patients (16 women, 44 men) who underwent unipolar femoral condylar FOCA with concomitant realignment between 1972 and 2012. The mean age of the patients was 28.9 years (10 to 62) and the mean follow-up was 11.4 years (2 to 35). Failure was defined as conversion to total knee arthroplasty, revision allograft, or graft removal. Clinical outcome was evaluated using the modified Hospital for Special Surgery (mHSS) score. RESULTS: A total of 14 grafts (23.3%) failed at a mean of 8.6 years (1.4 to 20.1). Graft survivorship was 87.3% (95% confidence interval (CI) 79.0 to 96.6), 85.0% (95% CI 75.8 to 95.3), 74.8% (95% CI 62.2 to 90.0), 65.2% (95% CI 49.9 to 85.2), and 59.8% (95% CI 43.5 to 82.1) at five, ten, 15, 20, and 25 years, respectively. A total of 23 patients (38.3%) developed complications, and 26 (43.3%) had a further operation. Persistent postoperative malalignment occurred more frequently in failed grafts (28.6% vs 4.3%; p = 0.023), and was a risk factor for graft failure (hazard ratio 6.55; 95% CI 1.61 27.71; p = 0.009). The mean mHSS score improved from 74.1 (40 to 91) preoperatively to 89.0 (66 to 100) at final follow-up (p < 0.001). CONCLUSION: Femoral condylar FOCA with concomitant realignment osteotomy provides excellent long-term graft survival and reliable functional improvement. Persistent malalignment may increase the risk for graft failure.

Fresh osteochondral allografts for posttraumatic knee defects: long-term followup.

Fresh osteochondral allograft transplantation has been an effective treatment option with promising long-term clinical outcomes for focal posttraumatic defects in the knee for young, active individuals. We examined histologic features of 35 fresh osteochondral allograft specimens retrieved at the time of subsequent graft revision, osteotomy, or TKA. Graft survival time ranged from 1 to 25 years based on their time to reoperation. Histologic features of early graft failures were lack of chondrocyte viability and loss of matrix cationic staining. Histologic features of late graft failures were fracture through the graft, active and incomplete remodeling of the graft bone by the host bone, and resorption of the graft tissue by synovial inflammatory activity at graft edges. Histologic features associated with long-term allograft survival included viable chondrocytes, functional preservation of matrix, and complete replacement of the graft bone with the host bone. Given chondrocyte viability, long-term allograft survival depends on graft stability by rigid fixation of host bone to graft bone. With the stable osseous graft base, the hyaline cartilage portion of the allograft can survive and function for 25 years or more.

Management of massive acetabular bone defects in revision arthroplasty of the hip using a reconstruction cage and porous metal augment.

AIMS: It may not be possible to undertake revision total hip arthroplasty (THA) in the presence of massive loss of acetabular bone stock using standard cementless hemispherical acetabular components and metal augments, as satisfactory stability cannot always be achieved. We aimed to study the outcome using a reconstruction cage and a porous metal augment in these patients. PATIENTS AND METHODS: A total of 22 acetabular revisions in 19 patients were performed using a combination of a reconstruction cage and porous metal augments. The augments were used in place of structural allografts. The mean age of the patients at the time of surgery was 70 years (27 to 85) and the mean follow-up was 39 months (27 to 58). The mean number of previous THAs was 1.9 (1 to 3). All patients had segmental defects involving more than 50% of the acetabulum and seven hips had an associated pelvic discontinuity. RESULTS: Three failures were observed in two hips, both of which had undergone a previous resection of a tumour affecting the acetabulum. Other complications included a late arterial injury, a sciatic nerve palsy, a dislocation treated with a femoral revision, a deep infection treated with irrigation and debridement and a fracture of the greater trochanter treated conservatively. The mean Oxford Hip Score significantly increased from 13.9 (2 to 23) to 28.7 (13 to 38) (p < 0.00001). The mean vertical distance between the centre of rotation of the hip and its normal location decreased from 30 mm to 10 mm. CONCLUSIONS: Acceptable early survivorship can be achieved using this novel technique, but it may be unsuitable for use in patients who have previously undergone the resection of a tumour involving the acetabulum. Cite this article: Bone Joint J 2017;99-B:607-13.

The role of cages in the management of severe acetabular bone defects at revision arthroplasty.

An uncemented hemispherical acetabular component is the mainstay of acetabular revision and gives excellent long-term results. Occasionally, the degree of acetabular bone loss means that a hemispherical component will be unstable when sited in the correct anatomical location or there is minimal bleeding host bone left for biological fixation. On these occasions an alternative method of reconstruction has to be used. A major column structural allograft has been shown to restore the deficient bone stock to some degree, but it needs to be off-loaded with a reconstruction cage to prevent collapse of the graft. The use of porous metal augments is a promising method of overcoming some of the problems associated with structural allograft. If the defect is large, the augment needs to be protected by a cage to allow ingrowth to occur. Cup-cage reconstruction is an effective method of treating chronic pelvic discontinuity and large contained or uncontained bone defects. This paper presents the indications, surgical techniques and outcomes of various methods which use acetabular reconstruction cages for revision total hip arthroplasty.

Outcome of revision hip arthroplasty in patients with a previous total hip replacement for developmental dysplasia of the hip.

Our aim was to determine if the height of the cup, lateralisation or the abduction angle correlated with functional outcome or survivorship in revision total hip replacement in patients with a previous diagnosis of developmental dysplasia of the hip. A retrospective investigation of 51 patients (63 hips) who had undergone revision total hip replacement was performed. The mean duration of follow-up was 119 months. Forty-one patients (52 hips) were available for both determination of functional outcome and survivorship analysis. Ten patients (11 hips) were only available for survivorship analysis. The height of the cup was found to have a statistically significant correlation with functional outcome and a high hip centre correlated with a worse outcome score. Patients with a hip centre of less than 3.5 cm above the anatomical level had a statistically better survivorship of the cup than those with centres higher than this. Restoration of the height of the centre of the hip to as near the anatomical position as possible improved functional outcome and survivorship of the cup.

Reconstruction of chronic abductor deficiency after revision hip arthroplasty using an extensor mechanism allograft.

This study reports the clinical outcome of reconstruction of deficient abductor muscles following revision total hip arthroplasty (THA), using a fresh-frozen allograft of the extensor mechanism of the knee. A retrospective analysis was conducted of 11 consecutive patients with a severe limp because of abductor deficiency which was confirmed on MRI scans. The mean age of the patients (three men and eight women) was 66.7 years (52 to 84), with a mean follow-up of 33 months (24 to 41). Following surgery, two patients had no limp, seven had a mild limp, and two had a persistent severe limp (p = 0.004). The mean power of the abductors improved on the Medical Research Council scale from 2.15 to 3.8 (p < 0.001). Pre-operatively, all patients required a stick or walking frame; post-operatively, four patients were able to walk without an aid. Overall, nine patients had severe or moderate pain pre-operatively; ten patients had no or mild pain post-operatively. At final review, the Harris hip score was good in five patients, fair in two and poor in four. We conclude that using an extensor mechanism allograft is relatively effective in the treatment of chronic abductor deficiency of the hip after THA when techniques such as local tissue transfer are not possible. Longer-term follow-up is necessary before the technique can be broadly applied.

Orthotopic bone transplantation in mice. I. Technique and assessment of healing.

A technique for orthotopic bone transplantation in mice has been developed. A section of recipient tibia was removed and replaced by a similar section from the donor animal. The graft was held in place by internal fixation. Bone healing was assessed clinically, histologically, radiologically, and by torsion testing. The most objective measurements of bone healing were the maximum torque and the energy absorbed by the bone to failure, which were derived from torsion testing. The degree of bone healing in donor-recipient combinations differing at H-2, non-H-2, or H-Y antigens was compared to the degree of healing in syngeneic controls. The incidence of nonunion was significantly increased in the H-2-disparate group. Furthermore, the extent of bone healing as measured by torsion testing was significantly reduced in both the H-2-and the H-Y-disparate groups. Thus, in the strain combinations tested, the order of importance of the genetic disparities influencing allogeneic bone grafts was H-2 greater than H-Y greater than non-H-2. The impaired healing of allogeneic bone grafts was probably immunologically mediated, as suggested by the observation that recipients of bone allografts rejected subsequent skin allografts in an accelerated manner.

Orthotopic bone transplantation in mice. II. Studies of the alloantibody response.

The alloantibody response of mice receiving cortical bone allografts was investigated. Such grafts were highly immunogenic, resulting in antibody responses at least as strong as those to skin allografts in the same combinations. The duration of the response to a single bone allograft was very prolonged (greater than 10 months). The antibody response was shown to be directed against H-2K, H-2D, Ia, and at least two non-H-2 antigens. Although the great majority of the parenchymal cells of the graft were dead, the immunogenicity of the graft required living cells, since bone that had previously been frozen and thawed was nonimmunogenic. By retransplanting bone allografts to a second recipient it was possible to demonstrate that the grafts remained immunogenic for at least 4 weeks after transplantation, indicating that the living immunogenic cells survived in the recipient for at least 4 weeks. Such cells may be certain cells of the cortical bone itself, or else residual bone marrow elements which adhere to the endosteal surface of the bone. The observation that a small subpopulation of living cells can provoke strong immune responses against a wide variety of antigens may have implications for understanding the immunogenicity of other types of allografts.

The pathologic features of massive osseous grafts.

The authors studied histologically six of 35 massive osseous or osteochondral transplants that had been inserted following radical resection of musculoskeletal malignancies. The six transplants consisted of three allografts removed because of infection within 12 weeks following insertion and two allografts and one vascularized autograft resected between 52 and 72 weeks because of recurrent tumor. The infected allografts were necrotic and showed extensive osteomyelitis and septic arthritis. Focal areas of cartilage still had chondrocytes. The two non-infected allografts were also necrotic, and host bone had grown into donor bone at the graft--host interface. The vascularized autograft was viable. Articular cartilage was present in only one of the non-infected allografts and was necrotic. Ultrastructurally, allograft cartilage, although necrotic, showed marked destruction of the matrix only when infected. Allograft bone seems to act purely as a strut, inciting little immune response. It is unable to respond to infection and has little osteoinductive ability. Vascularized autograft, in contrast, appeared to contribute to graft union. Articular cartilage can survive transplantation but may become necrotic and undergo marked degeneration when infected. The histologic findings and clinical courses support the conclusion that graft failure within 72 weeks after transplantation is not due to immunologic rejection.

Articular cartilage transplantation.

This report describes the biopsy findings in four of 30 patients treated with cadaver osteochondral shell allografts for osteoarthritis in the knee. This study demonstrates that graft cartilage cells can survive in excess of 25 months, and that host bone can completely replace graft bone by creeping substitution. An inflammatory reaction in synovium and bone marrow was found in only one of four cases. Graft failure was related to prolonged down time of donor cartilage in one case and mechanical factors related to osteoarthritis in the apposing femoral surface in other cases. The clinical success of these grafts is attributed to the prolonged viability of cartilage cells, the capacity of host bone to join graft cartilage without histologic reaction, and the host's immunologic tolerance, which obviates the need for immunosuppressive therapy.

Development, test reliability and validation of a classification for revision hip arthroplasty.

The objective of the study was to develop a valid and reliable classification system for failed hip arthroplasties. The study uses research principals derived from multi-attribute utility theory and consensus group techniques. The development of the severity measure was done in two phases. Phase I of the study included: (a) questionnaire development, (b) submission of the questionnaire to the respondents, (c) data synthesis of the responses and item reduction, and (d) classification development and inter-observer reliability testing. Phase II included: (a) resubmission of the instrument to the respondents for suggestions/feedback, (b) instrument revision by the co-investigators based on the respondents' second feedback, and (c) inter-observer reliability testing and intraoperative validity testing of the instrument. The questionnaires sought to capture expert opinion as to what clinical determinants obtained preoperatively (during patient interview, physical exam and review of plain radiographs - AP pelvis and hip lateral) that would in their clinical experience reveal intraoperative severity. There was an 80% (16/20) response rate from the outside experts invited to participate in the study. Based on item reduction and test retest analysis, a five-grade radiographic classification for the acetabulum as well as the femur was developed. This system was then reviewed by 13 of the initial outside experts (16, 80%) who participated in the first round. Inter-rater reliability testing of the final format of the classification revealed a weighted kappa statistic value of 0.88 between the two-blinded raters (inter-rater reliability) and 0.87 between the blinded raters and the reference standard (intraoperative validity). We conclude that the study developed a reliable and valid radiographic classification system for failed hip arthroplasty.

Varus osteotomy of the distal part of the femur. A survivorship analysis.

Varus osteotomy of the distal part of the femur is often the procedure of choice for the treatment of osteoarthrosis of the lateral compartment associated with genu valgum. We followed twenty-one knees (twenty patients) long term or until failure. At the most recent evaluation (average, 133 months; range, ninety-seven to 240 months), thirteen osteotomies were still successful, seven had failed, and one patient (in whom the knee had remained functional) had died. Of the seven failures, three occurred early (at twelve or twenty-four months) and four occurred late (between seventy-two and ninety-eight months). The probability of survival at ten years was 64 per cent (95 per cent confidence interval, 48 to 80 per cent), as determined with use of the Kaplan-Meier method. We concluded that, with proper selection of patients, this procedure is effective for the treatment of gonarthrosis of the lateral compartment associated with valgus deformity.

Late osteochondral allograft resurfacing for tibial plateau fractures.

Seventeen patients in whom secondary degenerative arthritis developed after a tibial plateau fracture underwent osteochondral allograft resurfacing of the involved plateau. The transplantation was done within twenty-four hours of procurement of the allograft from a cadaver donor so that viable cartilage would be used. There were sixteen tibial resurfacing grafts, and one patient had a tibial and femoral graft. Twelve patients have been followed for more than two years. A rating system for pain and function showed marked improvement in ten of the twelve patients. The clinical results were not related to age, interval from injury to grafting, type of graft, length of follow-up, or radiographic data. We believe that appropriate selection of patients for the procedure was the factor that led to the best results. Collapse of the osseous portion of the graft measuring more than three millimeters occurred in two patients, and there was obliteration of the cartilaginous joint space in one patient. This method of joint resurfacing requires minimum resection of tissue and avoids the use of a prosthesis. The ultimate fate of these grafts is not known, but the results in our series were encouraging. however, at this time the procedure should be restricted to younger patients with disabling, localized post-traumatic arthritis.

Revision of the acetabular component of a total hip arthroplasty with a massive structural allograft. Study with a minimum five-year follow-up.

The results of the placement of a massive structural acetabular allograft in conjunction with a revision total hip arthroplasty in thirty-two patients (thirty-tree hips) were evaluated at a minimum of five years. The graft supported more than 50 percent of the cup in all of the patients. The goals of a revision operation in a hip that has massive loss of bone are to provide support for the cup, to approximate the normal anatomy, to restore the length of the lower limb, and to restore bone stock should a future revision be necessary. Clinical and radiographic review at an average of seven years (range, five to eleven years) after the revision revealed that eighteen hips had needed no additional operation, seven hips had needed a repeat revision but the structural allograft was intact and had been used to support the cup at the repeat revision, and eight hips had had failure of both the prosthesis and the allograft. The result was considered a clinical and radiographic success when the hip score had increased at least 20 points, the cup was stable, the allograft had united, and no additional operation was necessary. According to these criteria, the rate of success was 55 percent (eighteen of thirty-three hips.) The only factor that was found to be clinically important with respect to outcome was the method of reconstruction. Seven of the eight hips that had been reconstructed with use of a roof-reinforcement ring and a structural allograft had a successful result at an average of 7.5 years (range, five to eleven years). The findings of the present study support the use of a structural allograft in the presence of massive loss of bone in order to achieve the goals of a revision hip replacement. Because of the high rate of success with acetabular reinforcement rings, we now use this method of reconstruction whenever a massive allograft is employed on the acetabular side.

The viability of articular cartilage in fresh osteochondral allografts after clinical transplantation.

The articular cartilage of four fresh osteochondral allografts was biopsied after transplantation, and its viability was studied by autoradiography. The biopsy specimens were labeled with both 3H-cytidine, for newly synthesized ribonucleic acid, and 35S-sulphate, for newly synthesized proteoglycans. The cartilage of a lateral humeral condylar graft at twelve months had 96 to 99 per cent labeled chondrocytes, the articular cartilage of a medial femoral condylar graft at twenty-four months showed 69 to 78 per cent labeled chondrocytes, and the cartilage of a medial tibial-plateau graft at forty-one months had 90 per cent labeled cells. At six years, a lateral tibial-plateau graft had 37 per cent labeled chondrocytes.

The immunogenicity of fresh and frozen allogeneic bone.

Both fresh and frozen allogeneic bone elicit both acellular and humoral immune response. This response includes the development of enhancing factors which block detectable immunity and probably protect the graft from rejection. There seems to be no evidence of an alteration in immunogenicity by freezing of the graft. The importance of these observations lies in the potential technique of employing fresh viable allografts; prior freezing and tissue matching for HL-A transplantation antigens should not be necessary.

Reconstruction of massive bone defects with allograft in revision total knee arthroplasty.

Allograft bone was used to reconstruct a defect in the proximal aspect of the tibia or the distal aspect of the femur, or both, in thirty knees of twenty-eight patients who had a revision total knee arthroplasty. The average age of the patients at the time of the index procedure was 65.8 years (range, twenty-four to eighty-nine years). At an average of fifty months (range, twenty-four to 132 months; median, thirty-six months) postoperatively, the score for twenty-three knees (twenty-one patients) had increased by at least 20 points, and these knees did not need additional operative treatment. Thus, the rate of success was 77 per cent. The procedure was considered a failure for the remaining seven knees because of infection (three), loosening of the tibial component (two), fracture of the graft (one), and non-union at the allograft-host junction (one). Properly applied allograft can be used to reconstruct massive bone defects, provide stability and support for implants, and restore bone stock in the event that additional operative treatment is necessary.

Virus-induced osteosarcoma in rats.

An experimental model for osteosarcoma was developed in which, after Moloney murine sarcoma virus was injected into the tibial marrow space of three strains of inbred neonatal rats, a highly malignant neoplasm arose within ten days. This tumor was readily maintained in tissue culture and was transplantable to adult rats. It arose in the metaphyseal marrow of several bones, was locally invasive, metastasized to the lungs, and histologically resembled osteosarcoma.

Immunogenicity of virus-induced rat osteosarcoma.

The immunogenicity of a virus-induced rat osteosarcoma was studied utilizing the lymphocyte microcytotoxicity test. Intratibial injection of murine sarcoma virus (Moloney) resulted in the development of palpable tumors at the injection site which on histopathological examination appeared to be osteosarcomas. In 73 per cent of animals injected these tumors progressed and metastasized to the lungs. Lymphocytes from these "progressor" animals demonstrated an ability to kill osteosarcoma cells in vitro (as quantitated in the microcytotoxicity test) while serum from these animals abrogated or blocked the cell-mediated cytotoxicity. In the remaining animals the tumors either failed to develop or regressed spontaneously. Lymphocytes from these "regressor" animals also demonstrated cytolytic activity against osteosarcoma cells in vitro, but serum failed to block the lymphocyte-mediated cytolysis. Both regressor and progressor groups demonstrated humoral cytotoxic antibodies to tumor antigen on the basis of the ability of their serum to kill tumor cells in vitro.