Ide C. Heyligers

High rate of failure of impaction grafting in large acetabular defects

We reviewed the results of 71 revisions of the acetabular component in total hip replacement, using impaction of bone allograft. The mean follow-up was 7.2 years (1.6 to 9.7). All patients were assessed according to the American Academy of Orthopedic Surgeons (AAOS) classification of bone loss, the amount of bone graft required, thickness of the graft layer, signs of graft incorporation and use of augmentation. A total of 20 acetabular components required re-revision for aseptic loosening, giving an overall survival of 72% (95% CI, 54.4 to 80.5). Of these failures, 14 (70%) had an AAOS type III or IV bone defect. In the failed group, poor radiological and histological graft incorporation was seen. These results suggest that impaction allografting in acetabular revision with severe bone defects may have poorer results than have previously been reported.

Effect of long-term preservation on the mechanical properties of cortical bone in goats

Background and purposeu2003Bones used in mechanical studies are frequently harvested from human cadavers that have been embalmed in a buffered formaldehyde solution. It has been reported that formaldehyde fixation or freezing hardly affects the mechanical properties of bone after a storage period of several weeks. However, human cadaver bones are usually stored for longer periods of time before use. We therefore investigated the effects of long-term embalming or freezing on the mechanical properties of cortical bone. Methodsu2003After 5 different storage periods (ranging from 0 to 12 months), goat femora and humeri were used to evaluate the effect of embalming and freezing on torsion, and on bending stiffness and strength. The effect on hardness and bone mineral density (BMD) was also evaluated. Resultsu2003Even after 1 year, no statistically significant differences could be found in stiffness, strength, and energy absorption when we compared embalmed or frozen bones to a fresh reference group. In addition, although we found no significant change in BMD, there appears to be a tendency to increasing hardness. Interpretationu2003We found that there was no effect on the mechanical properties of bone after storage periods of 1 year. We conclude that embalmed or frozen bones can safely be used for mechanical testing, at least for storage periods of up to one year.

Accuracy of diagnostic imaging techniques in the diagnosis of aseptic loosening of the femoral component of a hip prosthesis: A META-ANALYSIS

In this meta-analysis we included 32 English-language articles published between January 1975 and June 2004 on the diagnostic performance of plain radiography, subtraction arthrography, nuclear arthrography and bone scintigraphy in detecting aseptic loosening of the femoral component, using criteria based on the Cochrane systematic review of screening and diagnostic tests. The mean sensitivity and specificity were, respectively, 82% (95% confidence interval (CI) 76 to 87) and 81% (95% CI 73 to 87) for plain radiography and 85% (95% CI 75 to 91) and 83% (95% CI 75 to 89) for nuclear arthrography. Pooled sensitivity and specificity were, respectively, 86% (95% CI 74 to 93) and 85% (95% CI 77 to 91) for subtraction arthrography and 85% (95% CI 79 to 89) and 72% (95% CI 64 to 79) for bone scintigraphy. Although the diagnostic performance of the imaging techniques was not significantly different, plain radiography and bone scintigraphy are preferred for the assessment of a femoral component because of their efficacy and lower risk of patient morbidity.

Tricalcium-phosphate and hydroxyapatite bone-graft extender for use in impaction grafting revision surgery: AN IN VITRO STUDY ON HUMAN FEMORA

Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery. A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed.

Detection of living cells in non-processed but deep-frozen bone allografts.

Impacted morselized donor bone is successfully used to treat bone loss in revision total hip arthroplasties. It is generally thought, but not proven, that the processing and storage at −80xa0°C of the donor bone kills all cells. Because of the risk of contamination and to increase our understanding about the process of new bone formation after revision total hip arthroplasty, the aim of this study was to investigate whether the donor bone does contain vital cells. Samples from 11 femoral heads were obtained according to the American and European standards of bone banking, and tested for their capacity to give rise to proliferating cells, using tissue culture methods. All bone samples were stored at xa0−xa080°C for a minimum of 6xa0months. Bone sample cores were morselized and cultured for 6 weeks. Inverted phase contrast microscopy was used to evaluate cell growth. DNA marker analysis was used to confirm celluar identity.All bank bone samples gave rise to cell growth. The cell cultures showed osteoblastic characteristics in that they expressed high levels of alkaline phosphatase activity. DNA marker analysis showed identical alleles for cultured cells from frozen bone and freshly obtained buccal cells from the same donor, indicating that the cells growing from the banked bone were indeed originating from the donor tissue. It was therefore concluded that −80xa0°C freezing of bone tissue does not routinely kill cells within the tissue.

Osteogenic protein (OP-1, BMP-7) stimulates cartilage differentiation of human and goat perichondrium tissue in vitro

The objective of this study was to examine in vitro the influence of recombinant human osteogenic protein-1 [rhOP-1, or bone morphogenetic protein-7 (BMP-7)] on cartilage formation by human and goat perichondrium tissue containing progenitor cells with chondrogenic potential. Fragments of outer ear perichondrium tissue were embedded in clotting autologous blood to which rhOP-1 had been added or not added (controls), and the resulting explant was cultured for 3 weeks without further addition of rhOP-1. Cartilage formation was monitored biochemically by measuring [35S]-sulphate incorporation into proteoglycans and histologically by monitoring the presence of metachromatic matrix with cells in nests. The presence of rhOP-1 in the explant at the beginning of culture stimulated [35S]-sulphate incorporation into proteoglycans in a dose-dependent manner after 3 weeks of culture. Maximal stimulation was reached at 40 microg/mL (human explants: +148%; goat explants: +116%). Histology revealed that explants treated with 20-200 microg/mL of rhOP-1, but not untreated control explants, contained areas of metachromatic-staining matrix with chondrocytes in cell nests. It was concluded that rhOP-1 stimulates differentiation of cartilage from perichondrium tissue. The direct actions of rhOP-1 on perichondrium cells in the stimulation of chondrocytic differentiation and production of cartilage matrix in vitro provides a cellular mechanism for the induction of cartilage formation by rhOP-1 in vivo. Thus rhOP-1 may promote early steps in the cascade of events leading to cartilage formation and could prove to be an interesting factor in the regeneration of cartilage in articular cartilage defects.

Bone Metabolism after Total Hip Revision Surgery with Impacted Grafting: Evaluation using H2 15O and [18F]fluoride PET; A Pilot Study

PurposeTo evaluate bone blood flow and bone formation in patients after total hip revision surgery with impacted bone grafting using H215O and [18F]fluoride positron emission tomography (PET).ProceduresTo asses bone blood flow and bone metabolism in bone allograft after impaction grafting, four patients treated with total hip revision surgery were enrolled prospectively in this study. Six patients scheduled for primary hip arthroplasties were included as a control group. The study protocol consisted of three H215O and [18F]fluoride PET scans in each patient.ResultsBone blood flow increased significantly compared to the preoperative state in patients treated for primary hip arthroplasty. In patients undergoing revision surgery, bone blood flow was twofold to threefold higher compared to the preoperative state, but did not reach significance. Bone metabolism in patients undergoing revision was threefold higher 2xa0weeks postoperatively compared to the primary hip group. We found a significant correlation between Ki and bone blood flow.ConclusionsAllogeneic bone grafts induce a higher rate of local periprosthetic bone formation compared to periprosthetic bone formation after a primary total hip placement. In vivo coupling between bone blood flow and bone metabolism suggests that bone metabolism in allogeneic bone grafts may partly rely on bone blood flow adaptations.

A comparison of radiographic and scintigraphic techniques to assess aseptic loosening of the acetabular component in a total hip replacement.

BACKGROUNDnThe diagnosis of a loose total hip prosthesis is often established with use of radiographic and nuclear medicine techniques, but there is controversy about the relative utility of plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy. In this retrospective study, we evaluated the sensitivity, specificity, and interobserver reliability of these imaging modalities in patients suspected of having aseptic loosening of the acetabular component.nnnMETHODSnFrom 1994 to 1999, eighty-six consecutive patients with pain after a total hip arthroplasty were evaluated for possible loosening of the components. The imaging evaluation included plain radiography followed by a one-day protocol that included bone scintigraphy, subtraction arthrography, and nuclear arthrography. For this study, two experienced nuclear medicine physicians and two experienced radiologists, all of whom were blinded with respect to the clinical pretest data and the clinical outcome, retrospectively interpreted the diagnostic images. The sensitivity and the specificity of each imaging modality were established by comparing the findings obtained with each technique with those found at surgery or during the subsequent clinical course of the patient. Interobserver variability was determined with the intraclass correlation coefficient.nnnRESULTSnPlain radiography had a sensitivity of 85% (95% confidence interval, 71 to 94) and a specificity of 85% (95% confidence interval, 66 to 96) in detecting aseptic loosening of the acetabular component, but it had only fair interobserver variability (intraclass correlation coefficient, 0.37). For subtraction arthrography, the sensitivity was 72% (95% confidence interval, 57 to 84), the specificity was 70% (95% confidence interval, 50 to 86), and there was good interobserver variability (intraclass correlation coefficient, 0.71). For nuclear arthrography, the sensitivity was 57% (95% confidence interval, 41 to 71), the specificity was 67% (95% confidence interval, 46 to 84), and there was fair interobserver variability (intraclass correlation coefficient, 0.24). For bone scintigraphy, the sensitivity was 83% (95% confidence interval, 69 to 92), the specificity was 67% (95% confidence interval, 46 to 84), and there was moderate interobserver variability (intraclass correlation coefficient, 0.43).nnnCONCLUSIONSnPlain radiography had the highest diagnostic accuracy in the evaluation of aseptic loosening of the acetabular component. The diagnostic accuracy was increased when plain radiography was combined with bone scintigraphy or subtraction arthrography. However, we found considerable interobserver variability in image interpretation, even with experienced radiologists and nuclear medicine physicians.

Late failure of the polyethylene liner fixation in an uncemented total hip arthroplasty.

We report on the failure of fixation of a polyethylene liner of a Harris/Galante first-generation cementless acetabular component (Zimmer, Warsaw, IN). The failure was diagnosed 9 years after implantation. The polyethylene liner was partly dissociated in its metal shell, resulting in nearly complete wearing through of the metal caused by the femoral head. This wearing contributed to severe metallosis and osteolysis around both the femoral and the acetabular component. The possible failure mechanisms are described, and a complete review of the literature is given.

Diagnostic accuracy and interobserver variability of plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy in the assessment of aseptic femoral component loosening.

Background: Plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy are imaging techniques commonly used to identify aseptic femoral component loosening. Controversy exists about the relative utility of these techniques. Patients and methods: We evaluated the diagnostic accuracy and interobserver reliability of the four techniques in 78 consecutive patients (mean age 70xa0years, range 29–88xa0years) referred for evaluation of their femoral hip prostheses. The standard evaluation protocol consisted of plain radiography followed by subtraction arthrography, nuclear arthrography, and bone scintigraphy. Surgery or the subsequent clinical course of the patient was used as gold standard. Results: Overall, plain radiography had a sensitivity and specificity of 81 and 74%, respectively. Subtraction arthrography had a sensitivity of 47% and a specificity of 78%. Nuclear arthrography had a sensitivity of 69% and a specificity of 76%, and bone scintigraphy had a sensitivity of 88% with a specificity of 50%. Conclusion: We found considerable interobserver variability in all four techniques. Multivariate regression analysis revealed that bone scintigraphy and nuclear arthrography together made a significant contribution to the diagnosis when used in combination with plain radiography and are, when plain radiography is inconclusive, useful additional diagnostic techniques for the detection of femoral component loosening.