The histological and elemental characterisation of corrosion particles from taper junctions.

OBJECTIVES: This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. METHODS: The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris. RESULTS: The CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p < 0.001). The brown/red particles were significantly higher for ASR/SROM (p < 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride. CONCLUSION: This study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage.Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016;5:370-378. DOI: 10.1302/2046-3758.59.2000507.

Cementless total hip replacement without femoral osteotomy in patients with severe developmental dysplasia of the hip: minimum 15-year clinical and radiological results.

We describe the clinical and radiological results of cementless primary total hip replacement (THR) in 25 patients (18 women and seven men; 30 THRs) with severe developmental dysplasia of the hip (DDH). Their mean age at surgery was 47 years (23 to 89). In all, 21 hips had Crowe type III dysplasia and nine had Crowe type IV. Cementless acetabular components with standard polyethylene liners were introduced as close to the level of the true acetabulum as possible. The modular cementless S-ROM femoral component was used with a low resection of the femoral neck. A total of 21 patients (25 THRs) were available for review at a mean follow-up of 18.7 years (15.8 to 21.8). The mean modified Harris hip score improved from 46 points pre-operatively to 90 at final follow up (p < 0.001). A total of 15 patients (17 THRs; 57%) underwent revision of the acetabular component at a mean of 14.6 years (7 to 20.8), all for osteolysis. Two patients (two THRs) had symptomatic loosening. No patient underwent femoral revision. Survival with revision of either component for any indication was 81% at 15 years (95% CI 60.1 to 92.3), with 21 patients at risk. This technique may reduce the need for femoral osteotomy in severe DDH, while providing a good long-term functional result.

The S-ROM hydroxyapatite proximally-coated modular femoral stem in revision hip replacement: results of 397 hips at a minimum ten-year follow-up.

We report on 397 consecutive revision total hip replacements in 371 patients with a mean clinical and radiological follow-up of 12.9 years (10 to 17.7). The mean age at surgery was 69 years (37 to 93). A total of 28 patients (8%) underwent further revision, including 16 (4%) femoral components. In all 223 patients (56%, 233 hips) died without further revision and 20 patients (5%, 20 hips) were lost to follow-up. Of the remaining patients, 209 (221 hips) were available for clinical assessment and 194 (205 hips) for radiological review at mean follow-up of 12.9 years (10 to 17.7). The mean Harris Hip Score improved from 58.7 (11 to 92) points to 80.7 (21 to 100) (p < 0.001) and the mean Merle d'Aubigné and Postel hip scores at final follow-up were 4.9 (2 to 6), 4.5 (2 to 6) and 4.3 (2 to 6), respectively for pain, mobility and function. Radiographs showed no lucencies around 186 (90.7%) femoral stems with stable bony ingrowth seen in 199 stems (97%). The survival of the S-ROM femoral stem at 15 years with revision for any reason as the endpoint was 90.5% (95% confidence interval (CI) 85.7 to 93.8) and with revision for aseptic loosening as the endpoint 99.3% (95% CI 97.2 to 99.8). We have shown excellent long-term survivorship and good clinical outcome of a cementless hydroxyapatite proximally-coated modular femoral stem in revision hip surgery.

Ceramic-on-ceramic bearings in young patients: outcomes and activity levels at minimum ten-year follow-up.

We report the clinical and radiological outcomes of a series of contemporary cementless ceramic-on-ceramic total hip replacements (THRs) at ten years in patients aged ≤ 55 years of age. Pre- and post-operative activity levels are described. A total of 120 consecutive ceramic cementless THRs were performed at a single centre in 110 patients from 1997 to 1999. The mean age of the patients at operation was 45 years (20 to 55). At ten years, four patients had died and six were lost to follow-up, comprising ten hips. The mean post-operative Harris hip score was 94.7 (55 to 100). Radiological analysis was undertaken in 90 available THRs of the surviving 106 hips at final review: all had evidence of stable bony ingrowth, with no cases of osteolysis. Wear was undetectable. There were four revisions. The survival for both components with revision for any cause as an endpoint was 96.5% (95% confidence interval 94.5 to 98.7). The mean modified University of California, Los Angeles activity level rose from a mean of 6.4 (4 to 10) pre-operatively to 9.0 (6 to 10) at the ten-year post-operative period. Alumina ceramic-on-ceramic bearings in cementless primary THR in this series have resulted in good clinical and radiological outcomes with undetectable rates of wear and excellent function in the demanding younger patient group at ten years.

The use of ceramic-on-ceramic bearings in isolated revision of the acetabular component.

The practice of removing a well-fixed cementless femoral component is associated with high morbidity. Ceramic bearing couples are low wearing and their use minimises the risk of subsequent further revision due to the production of wear debris. A total of 165 revision hip replacements were performed, in which a polyethylene-lined acetabular component was revised to a new acetabular component with a ceramic liner, while retaining the well-fixed femoral component. A titanium sleeve was placed over the used femoral trunnion, to which a ceramic head was added. There were 100 alumina and 65 Delta bearing couples inserted. The mean Harris hip score improved significantly from 71.3 (9.0 to 100.0) pre-operatively to 91.0 (41.0 to 100.0) at a mean follow up of 4.8 years (2.1 to 12.5) (p < 0.001). No patients reported squeaking of the hip. There were two fractures of the ceramic head, both in alumina bearings. No liners were seen to fracture. No fractures were observed in components made of Delta ceramic. At 8.3 years post-operatively the survival with any cause of failure as the endpoint was 96.6% (95% confidence interval (CI) 85.7 to 99.3) for the acetabular component and 94.0% (95% CI 82.1 to 98.4) for the femoral component. The technique of revising the acetabular component in the presence of a well-fixed femoral component with a ceramic head placed on a titanium sleeve over the used trunnion is a useful adjunct in revision hip practice. The use of Delta ceramic is recommended.

Wear in alumina-on-alumina ceramic total hip replacements: a retrieval analysis of edge loading.

We analysed 54 alumina ceramic-on-ceramic bearings from total hip replacements retrieved at one centre after a mean duration of 3.5 years (0.2 to 10.6) in situ. These implants were obtained from 54 patients (16 men and 38 women) with a mean age of 67 years (33 to 88) who underwent revision for a variety of reasons. Posterior edge loading was found in the majority of these retrievals (32 out of 54). Anterosuperior edge loading occurred less often but produced a higher rate of wear. Stripe wear on the femoral heads had a median volumetric wear rate of 0.2 mm(3)/year (0 to 7.2). The wear volume on the femoral heads corresponded to the width of edge wear on the matching liner. Anteversion of the acetabular component was found to be a more important determinant than inclination for wear in ceramic bearings. Posterior edge loading may be considered to be a normal occurrence in ceramic-on-ceramic bearings, with minimal clinical consequences. Edge loading should be defined as either anterosuperior or posterior, as each edge loading mechanism may result in different clinical implications.

The role of patient factors and implant position in squeaking of ceramic-on-ceramic total hip replacements.

We investigated factors that were thought to be associated with an increased incidence of squeaking of ceramic-on-ceramic total hip replacements. Between June 1997 and December 2008 the three senior authors implanted 2406 primary total hip replacements with a ceramic-on-ceramic bearing surface. The mean follow-up was 10.6 years. The diagnosis was primary osteoarthritis in each case, and no patient had undergone previous surgery to the hip. We identified 74 squeaking hips (73 patients) giving an incidence of 3.1% at a mean follow-up of 9.5 years (4.1 to 13.3). Taller, heavier and younger patients were significantly more likely to have hips that squeaked. Squeaking hips had a significantly higher range of post-operative internal (p = 0.001) and external rotation (p = 0.003) compared with silent hips. Patients with squeaking hips had significantly higher activity levels (p = 0.009). A squeaking hip was not associated with a significant difference in patient satisfaction (p = 0.24) or Harris hip score (p = 0.34). Four implant position factors enabled good prediction of squeaking. These were high acetabular component inclination, high femoral offset, lateralisation of the hip centre and either high or low acetabular component anteversion. This is the largest study to date to examine patient factors and implant position factors that predispose to squeaking of a ceramic-on-ceramic hip. The results suggest that factors which increase the mechanical forces across the hip joint and factors which increase the risk of neck-to-rim impingement, and therefore edge-loading, are those that predispose to squeaking.

The effect of obesity on the mid-term survival and clinical outcome of cementless total hip replacement.

The outcome of total hip replacement (THR) is potentially affected by the body mass index (BMI) of the patient. We studied the outcome of 2026 consecutive primary cementless THRs performed for osteoarthritis. The mean follow-up was 6.3 years (0 to 11.71) and no patient was lost to follow-up for survival analysis. The patients were divided into two groups according to their BMI as follows: non-obese (BMI < 30 kg/m(2)) and obese (BMI > or = 30 kg/m(2)). The obese patient undergoing surgery was found to be significantly younger (p < 0.001). The log-rank test for equality of survival showed no difference in the mid-term survival (p = 0.552) with an estimated survival at 11 years of 95.2% (95% CI 92.5 to 98.0) in the non-obese and 96.7% (95% CI 94.9 to 98.5) in the obese groups. The clinical and radiological outcome was determined in a case-matched study performed on 134 obese individuals closely matched with 134 non-obese controls. The non-obese group was found to have a significantly higher post-operative Harris hip score (p < 0.001) and an increased range of movement, but overall satisfaction with surgery was comparable with that of the obese patients. Radiological analysis of the acetabular and femoral components showed no significant differences with regard to radiolucent lines, osteolysis, ingrowth of the femoral component, the acetabular inclination angle or alignment of the femoral component. Our results suggest that the survival of cementless THR is not adversely affected by obesity. Obese patients can therefore be counselled that despite a lower clinical score, they should expect to be satisfied with the result of their THR with a mid-term survival rate equivalent to that of non-obese patients.

The impact of obesity on the mid-term outcome of cementless total knee replacement.

We evaluated 535 consecutive primary cementless total knee replacements (TKR). The mean follow-up was 9.2 years (0.3 to 12.9) and information on implant survival was available for all patients. Patients were divided into two groups: 153 obese patients (BMI > or = 30) and 382 non-obese (BMI < 30). A case-matched study was performed on the clinical and radiological outcome, comparing 50 knees in each group. We found significantly lower mean improvements in the clinical score (p = 0.044) and lower post-operative total clinical scores in the obese group (p = 0.041). There was no difference in the rate of radiological osteolysis or lucent lines, and no difference in alignment. Log rank test for survival showed no significant differences between the groups (p = 0.167), with a ten-year survival rate of 96.4% (95% confidence interval (CI) 92 to 99) in the obese and 98% (95% CI 96 to 99) in the non-obese. The mid-term survival of TKR in the obese and the non-obese are comparable, but obesity appears to have a negative effect on the clinical outcome. However, good results and high patient satisfaction are still to be expected, and it would seem unreasonable to deny patients a TKR simply on the basis of a BMI indicating obesity.

Third-generation alumina-on-alumina ceramic bearings in cementless total hip arthroplasty.

BACKGROUND: Wear debris has been implicated in the pathogenesis of osteolysis. Alumina-on-alumina ceramic bearings have a low wear rate, which may reduce the prevalence of osteolysis. The purpose of this study was to determine the rates of wear and osteolysis associated with modern cementless hip arthroplasty with alumina-on-alumina bearings at five years. METHODS: We analyzed a series of 301 third-generation alumina-on-alumina cementless primary total hip replacements in 283 patients. The average age of the patients at the time of the arthroplasty was fifty-eight years. All procedures were performed with use of the same surgical technique and the same implant at a single center. At a minimum of five years postoperatively, ten patients had died and twenty-two patients were lost to follow-up. We assessed patients clinically and radiographically, and all retrieved bearings were analyzed for wear. RESULTS: At the time of the latest follow-up, the mean Harris hip score was 95 points. All surviving implants had radiographic evidence of stable bone ingrowth. There were nine revisions of one or both components. Four stems were revised following periprosthetic fracture, one stem was revised because of aseptic loosening at two months, and one stem was revised to facilitate a femoral shortening osteotomy. Two cups were revised because of psoas tendinitis, and both components of one arthroplasty were revised because of impingement and osteolysis. The rate of survival of both components, with revision because of aseptic loosening or osteolysis as the end point, was 99% at seven years. The retrieved femoral heads showed an early median wear rate of 0.2 mm(3) per year. CONCLUSIONS: Cementless primary total hip prostheses with a third-generation alumina-on-alumina bearing showed very low wear and were associated with minimal osteolysis at the time of follow-up, at a minimum of five years.

Wear and acetabular component orientation in third generation alumina-on-alumina ceramic bearings: an analysis of 33 retrievals [corrected].

We studied 33 third generation, alumina ceramic-on-ceramic bearings retrieved from cementless total hip replacements after more than six months in situ. Wear volume was measured with a Roundtest machine, and acetabular orientation from the anteroposterior pelvic radiograph. The overall median early wear rate was 0.1 mm(3)/yr for the femoral heads, and 0.04 mm(3)/yr for the acetabular liners. We then excluded hips where the components had migrated. In this stable subgroup of 22 bearings, those with an acetabular anteversion of < 15 degrees (seven femoral heads) had a median femoral head wear rate of 1.2 mm(3)/yr, compared with 0 mm(3)/yr for those with an anteversion of > or =15 degrees (15 femoral heads, p < 0.001). Even under edge loading, wear volumes with ceramic-on-ceramic bearings are small in comparison to other bearing materials. Low acetabular anteversion is associated with greater wear.

Polyethylene wear rates with Zirconia and cobalt chrome heads in the ABG hip.

We report a radiological analysis of 281 primary cementless ABG total hip arthroplasties performed between 1991 and 1994, with a mean follow-up of 78 months. We compare the polyethylene wear in hips with Zirconia ceramic heads manufactured prior to the introduction of hot isostatic pressing and hips with cobalt chrome heads. The mean linear wear rate was 0.19 mm/yr with 28mm Zirconia heads (n=203), 0.20 mm/yr with 32mm Zirconia heads (n=47) and 0.14mm/yr with 28mm cobalt chrome heads (n=31). We matched each of the 31 patients with 28mm cobalt chrome heads with a patient from the 28mm Zirconia group for gender and age. The mean linear wear rates in these two groups were 0.14mm/yr and 0.19mm/yr respectively (p<0.05). There were 19 revisions for osteo-lysis in 250 hips with Zirconia heads (7.6%) and no revisions in 31 hips with metal heads. We advocate regular review of patients with Zirconia on polyethylene bearing surfaces due to the high linear wear rates and associated osteolysis. (Hip International 2005; 15: 63-70).

Two knees or not two knees? Patient costs and outcomes following bilateral and unilateral total knee joint replacement surgery for OA.

AIMS: This study aims to address medical and non-medical direct costs and health outcomes of bilateral and unilateral total knee replacement from the patients' perspective during the first year post-surgery. METHODS: Osteoarthritis patients undergoing primary unilateral total knee or bilateral total knee replacement (TKR) surgery at three Sydney hospitals were eligible. Patients completed questionnaires pre-operatively to record expenses during the previous three months and health status immediately prior to surgery. Patients then maintained detailed prospective cost diaries and completed SF-36 and WOMAC Index each three months for the first post-operative year. RESULTS: Pre-operatively, no significant differences in health status were found between patients undergoing unilateral TKR and bilateral TKR. Both unilateral and bilateral TKR patients showed improvements in pain, stiffness and function from pre-surgery to 12 months post-surgery. Patients who had bilateral TKR spent an average of 12.3 days in acute hospital and patients who had unilateral TKR 13.6 days. Totally uncemented prostheses were used in 6% of unilateral replacements and 48% of bilateral replacements. In hospital, patients who had bilateral TKR experienced significantly more complications, mainly thromboembolic, than patients who had unilateral TKR. Regression analysis showed that for every one point increase in the pre-operative SF-36 physical score (i.e. improving physical status) out-of-pocket costs decreased by 94%. Out-of-pocket costs for female patients were 3.3 times greater than for males. CONCLUSION: Patients undergoing bilateral TKR and unilateral TKR had a similar length of stay in hospital and similar out-of-pocket expenditures. Bilateral replacement patients reported better physical function and general health with fewer health care visits one year post procedure. Patients requiring bilateral TKR have some additional information to aid their decision making. While their risk of peri-operative complications is higher, they have an excellent chance of good health outcomes at 12 months and are not going to be doubly "out-of-pocket" for the experience.

Macrophages at the skeletal tissue-device interface of loosened prosthetic devices express bone-related genes and their products.

Aseptic loosening of prosthetic arthroplasty is the most common reason for implant failure in adult orthopaedic reconstruction. At the interface of aseptic loosened prostheses, there is an abundance of particle-activated macrophages and other inflammatory cells. The role of these particle-laden macrophages in the osteogenic arm of the remodeling skeleton in this pathological condition is poorly understood. Molecular signaling by mesenchymal cells and mononuclear inflammatory cells residing in the interfacial tissues between bone and cement or prosthetic material of aseptically loosened joint prostheses was studied using in situ hybridization and immunohistochemical techniques. We found that a range of collagenous and noncollagenous matrix proteins, including osteopontin, osteocalcin, bone sialoprotein, and type I collagen, were produced in the periprosthetic tissue by foamy macrophages, as well as nearby osteogenic cells. The former accumulated in profusion in the three zones of interfacial tissues: pseudomembranous, fibrous, and osseous. Spindle mesenchymal cells in the fibrous zone failed to express any of the osteogenic mRNAs or proteins sought. The expression of bone-related genes and proteins by foamy macrophages at the interface of an aseptic loosened prosthesis may contribute to the disturbance of bone remodeling at this site.

The effect of substrate roughness and hydroxyapatite coating thickness on implant shear strength.

This study examined the role of substrate preparation and hydroxyapatite (HA) coating thickness on bone ongrowth and shear strength in a bilateral bicortical sheep model. Plasma-sprayed and grit-blasted titanium implants with different thickness HA coatings were examined at 4, 8, 12, and 26 weeks after implantation. Shear strength increased with time for all implants. Plasma-sprayed implants were superior to grit-blasted implants at all time points. The 100-microm-thick HA layer used in the present study provided greater fixation and ongrowth and less resorption compared with the 50-microm-thick layer. We did not observe any advantage in using a thicker HA coating for the titanium substrates examined.

Morphometric and mechanical evaluation of titanium implant integration: comparison of five surface structures.

Achieving a stable bone-implant interface is an important factor in the long-term outcome of joint arthroplasty. In this study, we employed an ovine bicortical model to compare the bone-healing response to five different surfaces on titanium alloy implants: grit blasted (GB), grit blasted plus hydroxyapatite (50 microm thick) coating (GBHA), Porocoat(R) (PC), Porocoat(R) with HA (PCHA) and smooth (S). Push-out testing, histology, and backscatter scanning electron microscope (SEM) imaging were employed to assess the healing response at 4, 8, and 12 weeks. Push-out testing revealed PC and PCHA surfaces resulted in significantly greater mechanical fixation over all other implant types at all time points (p <.05). HA coating on the grit-blasted surface significantly improved fixation at 8 and 12 weeks (p <.05). The addition of HA onto the porous coating did not significantly improve fixation in this model. Quantification of ingrowth/ongrowth from SEM images revealed that HA coating of the grit-blasted surfaces resulted in significantly more ongrowth at 4 weeks (p <.05).

Quantification of the bone-related mRNAs at the bone/prosthetic interface.

Aseptic loosening is one of the major reasons for failure of joint prostheses. The periprosthetic tissue has previously been described microscopically; however, little work has been devoted towards quantitating genes expressed by cells at the materials/tissue interface. This study aims to characterize the phenotypic expression of osteoblasts and test the feasibility of quantifying the level of gene expression in periprosthetic tissue sections by combining in situ hybridization and image analysis techniques. There are many factors to consider when quantifying mRNA, in that comparing labeling between different cDNA probes, these should have comparable length and base comparison. The probes should be labeled with the same specific activity, that is the amount of probe to label added is the same, both between different probes and between batches of the same probe. Chromagen color reactions are variable in that the color development is not always linear and more likely follows a sigmoidal curve. Samples should only be compared when it is known that the reaction has been in the linear range. The image analysis of such staining introduces further factors which should be considered and controlled. Color analysis is a very complex problem with respect to reproducibly analyzing histological sections. The brightness component of the image should be independent of the colors within the image, in conventional RGB (red, green and blue) signalling mode this is not possible, while when using HSI (hue saturation and intensity) mode this becomes possible, and factors like staining intensity and brightness of the image become much more accountable and controllable. With these factors identified, we consider that the quantitative image analysis approach does allow comparison of patterns of bone-related mRNAs and demonstrates differences in expression in these osteogenic factors depending on distance from the prosthesis, tissue type, patient and device.

Preliminary report of impaction grafting for exchange femoral arthroplasty.

Gie and Ling have described a method for femoral component revision using compressed morselized cancellous allograft and a cemented collarless polished taper stem. The authors report their early experience with this technique. Of the first 67 patients who had femoral exchange by impaction grafting, 60 were alive 2 to 5 years after hip revision; 2 hips failed because of late sepsis, and 5 patients were decreased. In 56 individuals available for review, the Harris Hip Score average was 90 points, with > 80% reporting no pain. On radiograph, 48% of the stems showed an average of 2.8 mm of subsidence in the polymethylmethacrylate mantle, but only 7% of the cement graft composites had subsided in the cortical tube. Lucent lines were rare, and in 93% of revised femurs the radiographs showed evidence of graft incorporation and bone remodeling. There were 6 reoperations in the group: 3 for late fracture of the femoral shaft and 3 for cup exchange (2 chronically dislocating, 1 loose). No evidence for femoral component loosening was found in this group. Further study is necessary, but these preliminary findings give rise to cautious optimism that this is a reliable method for femoral revision, reconstruction, and reconstitution.

Patterns of osteolysis around total hip components inserted with and without cement.

We reviewed the radiographs of 137 patients (137 hips) who had been managed with a total hip arthroplasty, with insertion of an extensively porous-coated femoral component without cement, because of osteoarthrosis or avascular necrosis. A porous-coated acetabular component had been inserted with cement in sixty-three of these patients (Group A) and without cement in seventy-four patients (Group B). The radiographs were examined for osteolysis, either directly adjacent to the joint or at locations remote from the joint. The mean duration of follow-up was 105 months (range, fifty-four to 142 months). The rate of osteolysis of the acetabulum in the unrevised hips in which the acetabular component had been inserted with cement was 37 per cent (nineteen of fifty-one). The osteolysis was most frequently of the linear type, a pattern that was associated with a high prevalence of loosening in the hips that had a cemented cup (30 per cent [nineteen of sixty-three]). The rate of acetabular osteolysis (18 per cent [thirteen of seventy-one]) in the patients who had a cup that had not been inserted with cement and that had not been revised was not as high as that associated with the surviving cups that had been inserted with cement (p < 0.05). The osteolysis associated with the cups that had not been inserted with cement was localized and expansile, and it was not associated with loosening of the component. However, it produced more loss of bone than did the linear pattern of osteolysis around the cemented cups.(ABSTRACT TRUNCATED AT 250 WORDS)