The results of 75 total hip replacements in 42 children with juvenile chronic arthritis are reported after a mean follow-up of 5.4 years. Their ages ranged from 11 to nearly 17 years at operation and many had active disease. Severe pain and marked stiffness of the hips were limiting their independence. At least half of the children were still growing and continued to grow after operation. The patients were carefully selected and gratifying results were obtained, but pre-operative assessment and overall supervision by a rheumatologist are important. Technical difficulties related to the size and maldevelopment of the hip are discussed. There was no infection and the single case of loosening of a femoral component after nine years has been successfully revised

It has been shown by mechanical analysis that by using cement to bond the stem of a femoral head prosthesis to bone two advantages are obtained when the conditions are compared with conventional methods. 1. "Fretting" between the implant and the living bone is eliminated. This source of persistent relative movement is probably the most important starting point for the progressive loosening of weight-bearing implants. 2. When cement is used the bond with the bone is exposed to stresses which are of an order three hundred times less than the shear strength of bone. The conventional prostheses expose the bond to compressive stresses which are near to the failure limits of the compressive strength of bone, especially in elderly patients with atrophic cortical bone in the femoral neck

Patients who had a revision total hip arthroplasty using the Bürch-Schneider anti-protrusio cage (APC) by a single surgeon have been reviewed after a minimum of five years. There were 63 operations in 58 patients with an average age of 63 years (41 to 83) at the time of revision. At an average follow-up of 8.5 years (5 to 18), 15 patients (25.9%) rated their results as excellent, 38 (65.5%) as good, and five (8.6%) as fair. Five further revisions of the acetabular prosthesis were required, three due to aseptic loosening, one for recurrent dislocation and one due to sepsis. Of the remainder, one was definitely loose, two probably loose, and 12 possibly so. Impressive augmentation of bone stock can be achieved with the anti-protrusio cage, while enabling the hip to be centred in its anatomical position

We compared the radiographic results of secondary total hip replacements, 99 following failed uncemented hemiarthroplasties and 21 following failed mould arthroplasties, with those of 825 primary cemented total hip replacements. The probability of occurrence of a number of radiological changes over time was calculated using survival analysis. The mean follow-up was 7.6 years (range one month to 20 years). The performance of the secondary total hip replacements varied with the preceding implant and was different for acetabular and femoral components. The incidence of radiological loosening was higher for femoral components implanted after failed hemiarthroplasties and for acetabular components after failed mould arthroplasties. However, the incidence of continuous radiolucent lines was lower for the acetabular components of converted hemiarthroplasties than for the primary replacements

One concern about the fixation of HA-coated implants is the possible disintegration of the surface, with the migration of HA granules into the joint space, producing third-body wear. We report a study of six revisions of HA-coated polyethylene RM cups at 9 to 14 years after successful primary arthroplasty. In all six hips, we found HA granules embedded in the articulating surface of the polyethylene, with abrasive wear of the cup and the metal femoral head. The cup had loosened in four hips and three showed severe osteolysis of the proximal femur. Third-body wear due to HA particles from implant coating may produce severe clinical problems with few early warning signs. Further clinical, radiological and histological observations are needed to determine the possible incidence of this late complication in the various types of coating of a variety of substrates

Aims

We present a retrospective review of patients treated with extracorporeally irradiated allografts for primary and secondary bone tumours with the mid- and long-term survivorship and the functional and radiographic outcomes.

We studied the rate of revision in 84 consecutive total hip replacements performed for failed osteosynthesis of femoral neck fractures and compared it with that for primary arthroplasty for osteoarthritis. The age and sex adjusted risk of prosthetic failure was 2.5 times higher after failure of fixation, but all the excess risk was in patients over 70 years of age. There were radiographic signs of loosening of the femoral component at five to 12 years after secondary arthroplasty in six of 33 survivors. In general, the results of secondary replacement were no worse than those obtained after primary arthroplasty for femoral neck fracture. We consider that internal fixation should be the primary procedure: total hip replacement is a safe secondary procedure when osteosynthesis fails

Fifteen patients with rheumatoid arthritis had 19 elbow arthroplasties with the Wadsworth type of surface replacement prosthesis. After a follow-up period averaging 30 months, 11 patients with 15 elbow arthroplasties were entirely satisfied with their freedom from pain and range of movement. Radiologically, however, the humeral component was loose in 10 of the 19 elbows and the ulnar component in 5. Two patients had reoperation, one to remove a prosthesis for early deep infection and one to exchange a humeral component which was loose. The risk of mechanical loosening is reduced by accurate positioning of the humeral component, but there is a high potential for failure. Changes in the design of the prosthesis and better instrumentation for alignment of the components are desirable. Prosthetic replacement of the elbow should still be regarded as experimental

The stabilised gliding knee prosthesis is a compromise between hinged joints and condylar prostheses. It is a two-piece implant designed to allow normal gliding movements of flexion and extension and which, stabilised by a connecting rod between the femoral and tibial components, allows a designed laxity of rotation and lateral movements. A modification of the original femoral component is described. Two hundred and forty-five knee replacement operations have been done between January 1973 and September 1977 and the results are reported. The results using this prosthesis are at least equal to those using hinged or condylar prostheses. So far there has been no case of spontaneous loosening of the components and the implant can be used in patients who, because of severe deformities and instability, are unsuitable for condylar prostheses

We made a semiquantitative study of the comparative histology of pseudomembranes from 12 loose cemented ceramic-ceramic and 18 metal-polyethylene total hip replacements. We found no significant difference in cellular reaction between the two groups, but there was a major difference in the origin of the particulate debris. In the metal-polyethylene group, polyethylene of articular origin was predominant, while in the ceramic-ceramic group the cellular reaction appeared to be a response to zirconia ceramic particles used to opacify cement used for fixation. Isolation and characterisation of the debris showed that the zirconia particles formed the greatest proportion (76%) in ceramic-ceramic hips, while alumina debris of articular origin formed only 12%. Our study has indicated that aseptic loosening of ceramic cups is not due to a response to debris generated at the articular interface, but to mechanical factors which lead to fragmentation of the cement

Increasing innovation in rapid prototyping (RP) and additive manufacturing (AM), also known as 3D printing, is bringing about major changes in translational surgical research.

This review describes the current position in the use of additive manufacturing in orthopaedic surgery.

Cite this article: Bone Joint J 2018;100-B:455-60.

We studied the migration of 58 cemented Hinek femoral components for total hip replacement,using roentgen stereophotogrammetric analysis over four years. The implants migrated faster during the first year than subsequently, and the pattern of migration in the second period was very different. During the first year they subsided, tilted into varus and internally rotated. After this there was slow distal migration with no change in orientation. None of the prostheses has yet failed. The early migration is probably caused by resorption of bone damaged by surgical trauma or the heat generated by the polymerisation of bone cement. Later migration may be due to creep in the bone cement or the surrounding fibrous membrane. The prosthesis which we studied allows the preservation of some of the femoral neck, and comparison with published migration studies of the Charnley stem suggests that this decreases rotation and may help to prevent loosening

Improvement in the life expectancy of patients with primary bone tumours has led to increased emphasis on limb salvage and preservation of function. Between 1979 and 1994 we used custom-made endoprostheses in 18 patients to reconstruct diaphyseal defects after excision of primary bone tumours. The mean age at operation was 26 years (9 to 64) and the median follow-up 65 months (6 to 188). Fifteen patients have survived and are free from local or metastatic disease. Local recurrence developed in one patient. Using the modified Enneking functional scoring system, 77% of the patients achieved 80% or more of their premorbid functional capability. Mechanical loosening, limb shortening and secondary osteoarthritis were the main complications. There were no infections. We conclude that diaphyseal endoprostheses offer a good clinical and functional outcome in the lower limb

Aims

Hydroxyapatite coatings for uncemented fixation in total knee arthroplasty can theoretically provide a long-lasting biological interface with the host bone. The objective of this study was to test this hypothesis with propriety hydroxyapatite, peri-apatite, coated tibial components using component migration measured with radiostereometric analysis over two years as an indicator of long-term fixation.

We report a high rate of failure of the Ring polyethylene cementless cup caused largely by granulomatous osteolysis. We have reviewed 126 prostheses inserted from 1986 to 1992 at from 11 to 90 months after surgery. There was radiological evidence of osteolytic granulomas adjacent to the external surface of the cup in 32%, appearing on average at three years from operation. In a subgroup of 59 prostheses followed for at least four years the incidence of such changes was 54%. A total of 27 cups (22%) have required revision, 21 for granulomatous loosening at an average follow-up of five years. In the retrieved prostheses there was obvious polyethylene abrasion and histological examination confirmed the presence of polyethylene wear debris. We found no significant correlation of osteolysis with cup size, although smaller cups were predominant among those having revision

We measured the stability of fixation in femoral neck fractures treated with von Bahr screws, investigated the influence of impaction and correlated peroperative stability with the clinical results. Stability was measured at operation using a metal probe fitted with strain gauges. Its tip was anchored in the subchondral bone of the femoral head and its lateral end was fixed in the lateral femoral cortex. The shearing force produced by longitudinal compression applied to the foot of the operated leg was recorded. The results in 41 consecutive patients all followed for 30 months, showed that fractures with early loosening or nonunion had all had significantly poorer stability than the fractures that had healed. Impaction improved stability in only 23 out of the 41 fractures; in the others stability had deteriorated or was unchanged

Sterilisation by gamma irradiation in the presence of air causes free radicals generated in polyethylene (PE) to react with oxygen, which could lead to loss of physical properties and reduction in fatigue strength. Tissue retrieved from failed total hip replacements often has large quantities of particulate PE and most particles associated with peri-implant osteolysis are oxidised. Consequently, an understanding of the cellular responses of oxidised PE particles may lead to clarification of the pathogenesis of osteolysis and aseptic loosening. We have used the agarose system to demonstrate the differential effects of oxidised and non-oxidised PE particles on the release of proinflammatory products such as interleukin-1β (IL-1β), IL-6, and tumour necrosis factor-α (TNF-α) from monocytes/ macrophages (M/M). Oxidised PE particles were shown to stimulate human M/M to phagocytose and to release cytokines. Oxidation may alter the surface chemistry of the particles and enhance the response to specific membrane receptors on macrophages, such as scavenger-type receptors

During the 11-year-period from 1970 to 1980, 799 total hip arthroplasties with metal-on-plastic prostheses were performed for primary osteoarthritis. In all cases high viscosity cement was used, but not under pressure; acetabular cartilage was removed, but the femoral canal was not plugged. The rate of revision and risk factors were evaluated by survivorship analysis. The overall cumulative revision rates were 11%, 14% and 19% after 8, 10, and 14 years respectively. When prophylactic antibiotics were not used, there was a significant risk of revision for infection. The risk of revision for mechanical loosening of both the acetabular and femoral components was significantly increased for men, younger patients, and if a snap-fit prosthesis with a 35 mm head and short wedged stem was used. The survivorship findings were validated by multivariate statistical analysis