Nine uncemented hip prostheses of modular design were revised because of late infection (2 cases), femoral stem loosening or fracture (2), loosening of threaded cups (3) and protrusion of bipolar cups (2). At surgery we found tissue discoloration and macroscopic corrosion in four of the nine prostheses, located at the head-neck junction. Histological examination in most cases showed extensive necrosis associated with metal particles, indicating metal toxicity. Metallographic examination of the prosthetic heads revealed structural imperfections and inhomogeneity of the metal. We suggest that the crevice between the head and neck is a potential site of corrosion in modular designs

Aims

The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions.

We present the results of 506 consecutive Howse hip arthroplasties with a minimum follow-up of 10 years. The mortality within one month of surgery was 0.79%. The early dislocation rate was 1.38%, two hips requiring revision. Nine hips developed deep sepsis (1.78%), eight of which required revision. At 10 years 42 hips (8.3%) had required revision, including 14 with aseptic acetabular loosening and 11 with femoral stem fractures. We feel that as judged by the dislocation rate and the need for subsequent revision, the Howse arthroplasty is an acceptable form of total hip replacement, particularly in the older patient and in those requiring total replacement for femoral neck fractures

To assess the effect of improved methods of femoral cementing on the loosening rates in young patients, we reviewed 50 'second-generation' cemented hip arthroplasties in 44 patients aged 50 years or less. The femoral stems were all collared and rectangular in cross-section with rounded corners. The cement was delivered by a gun into a medullary canal occluded distally with a cement plug. A clinical and radiographic review was undertaken at an average of 12 years (10 to 14.8) and no patient was lost to follow-up. No femoral component was revised for aseptic loosening, and only one stem was definitely loose by radiographic criteria. By contrast, 11 patients had undergone revision for symptomatic aseptic loosening of the acetabular component and 11 more had radiographic signs of acetabular loosening

The purpose of this study was to determine the biological effects of the elastic modulus of the femoral stem in canine hip arthroplasty. Cementless total hip arthroplasty was performed in 12 dogs, six had a low elastic modulus polyacetal resin stem and six had a high modulus stainless steel stem. The components were otherwise similar. At six and 12 months after operation, radiographic and histomorphometric analysis showed that those with steel implants had more cortical porosity than did the other group (p less than 0.01). We suggest that the elastic modulus of the implant is an important factor in controlling cortical bone resorption. A low modulus femoral prosthesis can significantly decrease bone resorption which might otherwise eventually lead to implant failure

The results of 140 total hip revision procedures for "non-septic" loosening, dislocation, and fracture of the femoral stem or shaft have been personally reviewed and rated by the Harris method. The minimum follow-up period was six months: thirty-three (24 per cent) showed excellent or good results, seventy-two (51 per cent) showed fair or poor results. Subsequent excision arthroplasty was performed in thirty-one patients. The infection rate for these revision procedures was very high, suggesting that many were already infected at the time of revision, and that every "loose" hip must be assumed to be infected until proved otherwise. The mortality rate of 3 per cent was surprisingly low after more than one major surgical procedure in these elderly patients

The newer techniques of cementing aim to improve interlock between cement and bone around a femoral stem by combining high pressure and reduced viscosity. This may produce increased embolisation of fat and marrow leading to hypotension, impaired pulmonary gas exchange and death. For this reason the use of high pressures has been questioned. We compared finger-packing with the use of a cement gun by measuring intramedullary pressures during the cementing of 31 total hip replacements and measuring physiological changes in 19 patients. We also measured pressure in more detail in a laboratory model. In the clinical series the higher pressures were produced by using a gun, but this caused less physiological disturbance than finger-packing. The laboratory studies showed more consistent results with the gun technique, but for both methods of cementing the highest pressures were generated during the insertion of the stem of the prosthesis

Aims

To compare the in vivo long-term fixation achieved by two acetabular components with different porous ingrowth surfaces using radiostereometric analysis (RSA).

We performed total hip replacement on 25 congenitally dislocated hips using corticocancellous bone from the femoral neck as a bone graft to reconstruct the deficient acetabulum. Two patients (two hips) died less than five years after surgery and three hips developed deep infection. We reviewed the remaining 20 hips at an average interval of 8.4 years (5.2 to 12.9). Their functional scores (modified Merle d'Aubigne and Postel) averaged 5.7 for pain, 5.1 for walking ability, and 4.2 for range of motion. Radiographs showed union and remodelling of the grafted bone in every case. There were radiological signs of aseptic loosening in three sockets (15%) without collapse of the grafted bone. None of the femoral stems was loose. No revision operation has been performed. Our results confirm the usefulness in the long term of femoral autografts for severe acetabular deficiency

We implanted 57 uncemented cobalt-chrome porous-coated collarless femoral components into 51 patients (mean age 49 years). At review, five to eight years postoperatively, good or excellent results were recorded in 70% by the Mayo Clinic hip evaluation and in 84% by the Harris hip score. Revision for aseptic loosening of the femoral stem was necessary in only one hip. Thigh pain diminished with time and was present in only two hips at the time of review. Endosteal bone formation was seen at the junction of the smooth and the porous segments of the stem in 94% of hips and in 60% it continued after three years. In 90% of hips, proximal femoral atrophy did not progress after three years. Discontinuous radiolucent lines were seen around 30% of stems, most commonly in zones I, IV and VII. They were not progressive in 94% and their presence did not correlate with the clinical outcome

Ten uncemented total hip replacements were performed in 1975 using an implant in which the cobalt-chrome femoral stem was coated to give a porous surface. In all but one case a high-density polyethylene head was used. The radiological changes in the upper femoral shafts were assessed between three and nine years later. Seven showed extensive stress-relieving changes, loss of calcar, stress fractures at the root of the lesser trochanter with subsequent detachment, and osteoporosis followed by avulsion of the greater trochanter. In these seven patients the lower part of the stem appeared to be soundly embedded, although in only one was there evidence of bony incorporation. It is suggested that if the fixation of a fully coated implant of this sort remains sound, gross atrophy of the upper femoral shaft develops after five years. This atrophy, associated with an implant which can be removed only at the expense of further bone destruction, presents substantial problems if revision is needed

Aims

Metaphyseal fixation during revision total knee arthroplasty (TKA) is important, but potentially difficult when using historical designs of cone. Material and manufacturing innovations have improved the size and shape of the cones which are available, and simplified the required bone preparation. In a large series, we assessed the implant survivorship, radiological results, and clinical outcomes of new porous 3D-printed titanium metaphyseal cones featuring a reamer-based system.

We report the clinical and tribological performance of 67 ceramic acetabular prostheses implanted between 1976 and 1979 without bone cement. They articulated with ceramic femoral heads mounted on mental femoral stems. After a mean elapsed period of 144 months, 59 sockets were radiographically stable but two showed early signs and six showed late signs of loosening. Four of the loose sockets have been revised. Histological analysis of the retrieved tissue showed a fibrous membrane around all the implants, with fibrocartilage in some. There was no bone ingrowth, and the fibrous membrane was up to 6 mm thick and infiltrated with lymphocytes, plasma cells, and macrophages. Intra- and extracellular birefringent wear particles were seen. Tribological analysis showed total wear rates in two retrieved alumina-on-alumina joints of 2.6 microns per year in a stable implant and 68 microns in a loose implant. Survival analysis showed a revision rate of 12.4% at 136 months

We reviewed 19 patients who presented with aggressive granulomatosis around the femoral stem after hip replacement. All had experienced stress pain and had required revision arthroplasty on average 8.8 years after the primary operation. Fifteen patients were men and four were women; none had rheumatoid arthritis. One patient had an uncemented Moore hemiprosthesis; the others all had cemented total hip replacements. When first detected, the granulomatous lesions were multifocal in 13 patients. The first granuloma was in the region of the lesser trochanter in 10, and near the tip of the stem in only two. Speed of growth varied but on average there was doubling of the area on anteroposterior films in 2.2 years (range 6 months to 4.6 years). Aggressive granulomatous lesions in replaced hips are a distinct condition, different from simple loosening or infection; the lesions may grow rapidly, so revision surgery is indicated soon after diagnosis

Aims

Short, bone-conserving femoral components are increasingly used in total hip arthroplasty (THA). They are expected to allow tissue-conserving implantation and to render future revision surgery more straightforward but the long-term data on such components is limited. One such component is the global tissue-sparing (GTS) stem. Following the model for stepwise introduction of new orthopaedic implants, we evaluated early implant fixation and clinical outcome of this novel short-stem THA and compared it to that of a component with established good long-term clinical outcome.

We report a prospective study of the use of intramedullary bone blocks to improve the fixation of a matt-finish femoral stem in Charnley low-friction arthroplasties. There were 379 patients (441 hips), but at a minimum follow-up of ten years there were 258 arthroplasties in 221 patients including some which had been revised. The mean age at surgery was 41 years (17 to 51) and the mean follow-up was 13.4 years (1 to 20 including the early revisions). Nine stems (3.5%) had been revised for aseptic loosening, but there were no stem fractures. Survivorship of stems was 99.2% at ten years and 94.35% at 15 and 20 years. We found that the patient’s gender, the position of the stem and the experience of the surgeon all influenced the outcome. Our findings suggest that using our method of stem fixation, follow-up of over 11 years was needed to reveal the effects of endosteal cavitation of the femur, and of over 13 years to assess any divergence between the clinical and the radiological outcomes of stem fixation

We studied the risk of recurrent dislocation in 121 primary and 39 revision Charnley or Charnley hybrid total hip arthroplasties which had been treated for a primary dislocation between 1979 and 1995. Only 35% of these hips had no further dislocation or a revision for instability within one year. The rates of survival gradually declined with time or if a second, third or fourth dislocation occurred. The risk of recurrence was greater in men, but was not related to age, diagnosis, time of the first dislocation or whether the index operation had been a primary or a revision procedure. Operative treatment included 15 reoperations leaving intact components, 50 revisions, and permanent removal of the femoral stem in seven patients. The operation was successful in four patients with reoperations and in 36 who had an exchange procedure within two years. Treatment was successful in 35 of 49 hips in which it was possible to correct a technical error compared with 5 out of 16 hips in which malposition of the components was not seen (p = 0.007)

Polyethylene liners of modular acetabular components wear sometimes need to be replaced, despite the metal shell being well fixed. Replacing the liner is a relatively simple procedure, but very little is known of the outcome of revision. We prospectively followed up 1126 Harris-Galante I metal-backed, uncemented components for between nine and 19 years. We found 38 (3.4%) liners of 1126 acetabular components wore and required revision. These revisions were then followed up for a mean of 4.8 years. The rate of dislocation was 28.9%. Nine of the dislocations occurred once and two were recurrent. The overall secondary revision rate was three of 38 total hip replacements (7.9%) at a mean follow-up of 4.8 years. This gives a 92.1% survivorship (35 of 38) at under five years. In isolated revision of a liner, we had a complication rate of 23% (three of 13). In revision of a liner combined with revision of the femoral stem, there was a complication rate of 48% (12 of 25). We discuss possible reasons for the high dislocation rates. Leaving the well-fixed acetabular shell in situ leads to an increased risk of instability. However, this needs to be balanced against the otherwise low complication rate for revision of the liner. Patients should be consented accordingly