A 28-year clinical and radiological follow-up of alumina ceramic-on-crosslinked polyethylene total hip arthroplasty: a follow-up report and analysis of the oxidation of a shelf-aged acetabular component.

AIMS: Our aim in this study was to describe a continuing review of 11 total hip arthroplasties using 22.225 mm Alumina ceramic femoral heads on a Charnley flanged femoral component, articulating against a silane crosslinked polyethylene. PATIENTS AND METHODS: Nine patients (11 THAs) were reviewed at a mean of 27.5 years (26 to 28) post-operatively. Outcome was assessed using the d'Aubigne and Postel, and Charnley scores and penetration was recorded on radiographs. In addition, the oxidation of a 29-year-old shelf-aged acetabular component was analysed. RESULTS: The mean clinical outcome scores remained excellent at final follow-up. The mean total penetration remained 0.41 mm (0.40 to 0.41). There was no radiographic evidence of acetabular or femoral loosening or osteolysis. There was negligible oxidation in the shelf-aged sample despite gamma irradiation and storage in air. CONCLUSION: These results highlight the long-term stability and durability of this type of crosslinked, antioxidant containing polyethylene when used in combination with a small diameter alumina ceramic femoral head. Cite this article: Bone Joint J 2017;99-B:1286-9.

Microseparation, fluid pressure and flow in failures of metal-on-metal hip resurfacing arthroplasties.

OBJECTIVES: Metal-on-metal (MoM) hip resurfacing was introduced into clinical practice because it was perceived to be a better alternative to conventional total hip replacement for young and active patients. However, an increasing number of reports of complications have arisen focusing on design and orientation of the components, the generation of metallic wear particles and serum levels of metallic ions. The procedure introduced a combination of two elements: large-dimension components and hard abrasive particles of metal wear. The objective of our study was to investigate the theory that microseparation of the articular surfaces draws in a high volume of bursal fluid and its contents into the articulation, and at relocation under load would generate high pressures of fluid ejection, resulting in an abrasive water jet. METHODS: This theoretical concept using MoM resurfacing components (head diameter 55 mm) was modelled mathematically and confirmed experimentally using a material-testing machine that pushed the head into the cup at a rate of 1000 mm/min until fully engaged. RESULTS: The mathematical model showed the pattern but not the force of fluid ejection, the highest pressures were expected when the separation of the components was only a fraction of one millimetre. The experimental work confirmed the results; with the mean peak ejection pressure of 43 763 N/m(2) equivalent to 306 mmHg or 5 psi. CONCLUSIONS: The mechanical effect of the high-pressure abrasive water jet is the likely cause of the spectrum of complications reported with metal-on-metal resurfacing. Investigating serum levels of metallic elements may not be the best method for assessing the local mechanical effects of the abrasive water jet.

Charnley low-friction arthroplasty in teenage patients: the ultimate challenge.

Increasing follow-up identifies the outcome in younger patients who have undergone total hip replacement (THR) and reveals the true potential for survival of the prosthesis. We identified 28 patients (39 THRs) who had undergone cemented Charnley low friction arthroplasty between 1969 and 2001. Their mean age at operation was 17.9 years (12 to 19) and the maximum follow-up was 34 years. Two patients (4 THRs) were lost to follow-up, 13 (16 THRs) were revised at a mean period of 19.1 years (8 to 34) and 13 (19 THRs) continue to attend regular follow-up at a mean of 12.6 years (2.3 to 29). In this surviving group one acetabular component was radiologically loose and all femoral components were secure. In all the patients the diameter of the femoral head was 22.225 mm with Charnley femoral components used in 29 hips and C-stem femoral components in ten. In young patients who require THR the acetabular bone stock is generally a limiting factor for the size of the component. Excellent long-term results can be obtained with a cemented polyethylene acetabular component and a femoral head of small diameter.

The principle of low frictional torque in the Charnley total hip replacement.

The design of the Charnley total hip replacement follows the principle of low frictional torque. It is based on the largest possible difference between the radius of the femoral head and that of the outer aspect of the acetabular component. The aim is to protect the bone-cement interface by movement taking place at the smaller radius, the articulation. This is achieved in clinical practice by a 22.225 mm diameter head articulating with a 40 mm or 43 mm diameter acetabular component of ultra-high molecular weight polyethylene. We compared the incidence of aseptic loosening of acetabular components with an outer diameter of 40 mm and 43 mm at comparable depths of penetration with a mean follow-up of 17 years (1 to 40). In cases with no measurable wear none of the acetabular components were loose. With increasing acetabular penetration there was an increased incidence of aseptic loosening which reflected the difference in the external radii, with 1.5% at 1 mm, 8.8% at 2 mm, 9.7% at 3 mm and 9.6% at 4 mm of penetration in favour of the larger 43 mm acetabular component. Our findings support the Charnley principle of low frictional torque. The level of the benefit is in keeping with the predicted values.

Charnley low-frictional torque arthroplasty: follow-up for 30 to 40 years.

Of the 11 054 Charnley low-frictional torque arthroplasties carried out at our hospital between 1962 and 1977, 110 (94 patients) had a minimum follow-up of 30 years with a mean of 32.3 years (30.0 to 40.5). The mean age of the patients at operation was 43.3 years (17.0 to 65.0) and 75.7 years (51.0 to 97.0) at follow-up. Overall, 90% of hips (99) were free from pain and activity was reported as normal in 58% of the patients. A total of 13 hips (11.8%) were revised at a mean follow-up of 32.3 years (30.0 to 39.5), with wear and loosening of the acetabular component as the main indications. The clinical results did not reflect the mechanical state of the implant. Follow-up with sequential radiographs of good quality is essential. Revision for radiological changes alone must be accepted if gross loss of bone stock is to be avoided. Improvements in the design, materials and operative technique, based on the long-term outcome, are highlighted.

Increasing patients' body mass. Are the criteria for testing stemmed femoral components in total hip arthroplasty still valid?

The increasing incidence of obesity in the population is a topic of current interest. This trend is reflected in patients undergoing primary Charnley hip replacement. Over a 21 year period from January 1986 to October 2006, during which 6910 primary operations were performed, the body mass of patients increased at a mean rate of 0.48 kg/year. The findings suggest that the test criteria for the endurance of stemmed femoral components be modified. The maximum load should be increased from 2.3 kN to 2.5 kN to reflect patients' increasing weight. The duration of the test should be increased from 5 x 10(6) cycles during which the 'femoral component shall not fracture' to 10 x 10(6) cycles in order to reflect not only the patients' activity level but also the 4-11 year period at risk for stem fracture, and so 'reflect developing clinical experience'.

Charnley low-friction arthroplasty: survival patterns to 38 years.

We studied survival to 38 years after Charnley low-friction arthroplasty of the hip. We used revision as an end-point, while adopting a policy of regular follow-up and early revision for radiological changes alone if indicated. Between November 1962 and June 2005, 22,066 primary low-friction arthroplasties (17,409 patients) had been performed at Wrightington Hospital by more than 330 surgeons. By June 2006, 1001 (4.5%) hips had been revised and 1490 patients (2662 hips, 12%) had died. At 31 years, where a minimum of 40 hips were still attending follow-up, survival with revision for infection as an endpoint was 95%, for dislocation 98%, for a fractured stem 88.6%, for a loose stem 72.5% and for a loose acetabular component 53.7%. Wear and loosening of the ultra-high-molecular-weight polyethylene acetabular component were the main long-term problems. We conclude that regular follow-up after hip replacement is essential and that all operative findings should be recorded at revision.

Periprosthetic femoral fractures treated with a modular distally cemented stem.

PURPOSE: To assess the treatment outcome of revision hip arthroplasty for Vancouver type B3 periprosthetic femoral fractures using a modular distally cemented stem. METHODS: 22 men and 14 women (37 hips) aged 66 to 79 (mean, 70) years underwent revision hip arthroplasty for Vancouver type B3 periprosthetic femoral fractures. The indication for surgery was periprosthetic fracture with stem loosening and loss of proximal bone stock. The patients were referred from other hospitals after previous surgeries had failed: 8 with 3 previous surgeries, 19 with 2, and 9 with one. Using a transtrochanteric approach, the existing prosthesis was removed and a modular proximal femoral replacement stem was inserted, bypassing the area of proximal femoral fracture and bone loss. The stem was distally cemented. Patients were immobilised within 48 hours of surgery. RESULTS: Patients were followed up for a mean of 14 (range, 8-18) years. The mean Harris hip score improved from 29 (range, 5-40) to 78 (range, 56-88); 24 patients attained excellent or good scores (>80), 10 attained fair, and 2 attained poor scores. The mean healing time was 7 (range, 6-14) months; there was no non-union. Improvement in proximal bone stock was noted on serial radiographs. None of the stems had cement fracture or migration, requiring revision. Two (5%) of the patients had dislocations. CONCLUSION: Vancouver type B3 periprosthetic femoral fractures can be successfully treated with a distally cemented modular proximal femoral replacement prosthesis.

The microbiology of infected hip arthroplasty.

Infection following joint replacement surgery although rare presents a challenging problem. Bacterial resistance to antibiotics is an emerging problem. We analysed the microbiology of 337 single-stage revisions for deep infection. Coagulase negative staphylococcus was found to be the predominant organism, although staphylococcus aureus is gaining importance. Gentamicin only provides cover for 64.1% of organisms. Resistance to this commonly used antibiotic prophylaxis is escalating. Fusidic acid and erythromycin provide improved cover. We would suggest on a microbiological basis that these antibiotics be considered for addition to acrylic bone cement. This will provide local antibiotic delivery when performing a revision for deep infection.

The Charnley hip replacement -- 43 years of clinical success.

The Charnley low-frictional torque arthroplasty of the hip with 22.225 mm diameter head and thick ultra high molecular weigh polyethylene cup, both components grouted with cold curing acrylic cement, has reached 43 years of clinical success. Follow-up past 30 years is now available. Over 96% of patients are satisfied with the result. Post operative activity level is a reflection of patient selection. The neuropathic nature of the new joint does not reflect the mechanical state of the arthroplasty: regular follow-up with good quality radiographs is essential. Revisions may have to be undertaken for asymptomatic radiographic changes: a principle that must be understood and accepted before the primary procedure. The long-term problems are wear and cup loosening and strain shielding of the proximal femur. Long-term success will be further extended by understanding and practical application of the principles at the primary procedure and use of low wear materials for the articulation. The operation of total hip arthroplasty marks the beginning and not the end of treatment.

The angle-bore acetabular component and dislocation after revision of a failed total hip replacement.

We reviewed 1039 revision total hip replacements where an angle-bore acetabular component was used. After a mean follow-up of nine years (0 to 20.6), the incidence of revision for dislocation was 2.1% (22 revisions), a success rate of 97.9%. In 974 revisions, where the indication was other than dislocation, the success rate was 98.5%. Of the 65 revisions for dislocation, 58 (89.2%) were successful after the first revision and a further five after the second revision, an overall success of 96.9%. Two patients elected to have their implants removed. Dislocation after revision of failed total hip replacement is a complex issue. There is often no single cause and no simple solution. The angle-bore acetabular component, in combination with a 22.225-mm diameter femoral head, offers a high level of success.

Charnley low-frictional torque arthroplasty for avascular necrosis of the femoral head.

Forty-nine patients (mean age, 37 years; 20-50 years) had had 69 Charnley low-frictional arthroplasties for avascular necrosis of the femoral head. Their mean follow-up was 13.4 years (2-25 years). Five patients (8 hips) had no continuing follow-up, 5 (8 hips) are known to have died, 6 (7 hips) had had a revision at a mean follow-up of 16.4 years (11-25 years): 6 for cup loosening and 1 for a fractured stem and a loose cup. The remaining 33 patients (46 hips) had an excellent clinical result with all stems remaining soundly fixed, but 6 cups were radiologically loose at a mean follow-up of 16 years and 4 months. Wear and cup loosening are the main problems limiting the survival of the arthroplasty.

Low-friction arthroplasty of the hip using alumina ceramic and cross-linked polyethylene. A 17-year follow-up report.

We report the results of our continued review of 11 total hip arthroplasties using 22.225 mm alumina ceramic femoral heads on a Charnley flanged stem, articulating with chemically cross-linked polyethylene. There was an initial bedding-in of up to 0.41 mm at the articular surface in the first two years. This had not progressed further, at a minimum follow-up of 15 years. Radiographically no femoral or acetabular component showed loosening or osteolysis.

Prediction of Charnley femoral stem aseptic loosening by early post-operative radiological features.

We describe the association between immediate post-operative radiological appearances and early aseptic failure of total hip replacement. Sixty-three hips were entered into the aseptic failure group and 138 into the control group. Alignment of the femoral stem was not associated with failure (p=0.283). Thickness of the cement mantle was associated with failure in Gruen zones 6 (p=0.040) and 7 (p=0.003). A significant association for the presence of radiolucent lines was found for Gruen zones 3 (p=0.0001) and 5 (p=0.0001). Grade of cementation was associated with failure for Barrack grades C (p=0.001) and D (p=0.001). This study has demonstrated that easily applied radiological criteria can be used to identify 'hip arthroplasties at risk' from the immediate post-operative radiograph.

Effect of hip stem taper on cement stresses.

The aim of this study was to use finite element models to investigate the effect of the design of the taper of polished, collarless, total hip replacement femoral components on stresses in the cement mantle surrounding the component. A single-taper prosthesis, double-taper prosthesis, and triple-taper prosthesis were compared. Peak stresses and stress distributions in the cement mantle were found to be a function of taper design, although the differences between designs were minor. Using a probability of failure technique based on the initial cement stress distribution, a triple-taper prosthesis was predicted to cause less cement mantle damage (0.15% of the volume of the cement mantle failing after 20 million loading cycles) than a double-taper prosthesis (0.74%) or a single-taper prosthesis (1.50%). Further research is required to confirm this finding.