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

A high percentage of hips in patients with rheumatoid arthritis presenting for total joint replacement have protrusio deformity with extremely thin medial acetabular walls. Biomechanical principles suggest that, to prevent inward migration of the acetabular component, the prosthesis should be positioned laterally near the acetabular rim. To reinforce the medial wall, the femoral head is fashioned into a solid graft which is anchored against the medial wall as a plug, minimising the amount of cement used and making the use of wire mesh and restraining rings about the acetabulum unnecessary. A series of nine operations on seven patients is presented. Serial radiographs, tomograms and scintigrams taken after operation suggest satisfactory incorporation of the grafts, and no complications have been encountered in a follow-up period ranging from three months to two years

Although about 200 000 cementless Zweymüller-Alloclassic total hip arthroplasties (THAs) were carried out worldwide in the last decade, the survival analysis of these prostheses was not available in the 2000 report of the Swedish national hip arthroplasty registry. We report a prospective survivorship analysis of 200 consecutive grit-blasted cementless Alloclassic primary THAs carried out since 1988. Using surgical, clinical and radiological endpoints for the stem and the threaded cup the ten-year survivorship was 91.5% for reoperation for any cause, 96.4% for hip pain (Merle d’Aubigné score < 5 points, clinical failure), 99.4% for definite aseptic loosening (radiological failure) and 99.3% for revision for aseptic loosening. Using the Swedish registry criteria of primary osteoarthritis and revision for aseptic loosening as the endpoint, the survival rate of 99.1% at ten years for the subgroup of 157 Alloclassic THAs in osteoarthritis compares favourably with that of the best modern cemented hip replacements reported in the Swedish arthroplasty registry

In 1988 we reported a ten-year review of 83 surviving patients from a group of 135 (146 prostheses) who had undergone primary hip replacement using the Stanmore prosthesis. We have now reviewed 44 of these patients at 15 to 16 years. Four patients had undergone revision, but the other 40 were all satisfied with the result of their hip replacement, 36 having little or no pain. Functional activities had decreased, but were still adequate for their average age of 81 years. There had been definite migration of the cup and/or femoral component in three hips, wear of the cup in ten and resorption of the calcar in six. Of the 24 hips inserted with radiopaque cement, eight showed an increase in radiolucent lines at the acetabular interface. The cumulative survival rate of the prosthesis was 91% at 15 to 16 years

Aims

The objective of this study was to compare early postoperative functional outcomes and time to hospital discharge between conventional jig-based total knee arthroplasty (TKA) and robotic-arm assisted TKA.

We report the long-term outcome of 218 Charnley low-friction arthroplasties in 141 patients who were 40 years old or younger at the time of surgery. The minimum follow-up was ten years with a mean of 16 years. The probability of the femoral component surviving 20 years was 86% and of the acetabular component, 84%. The chance that both components would survive for this period was 75%. The pathological diagnosis significantly influenced implant survival. In rheumatoid patients the probability of both components surviving at 20 years was 96% compared with 51% in patients with osteoarthritis. Clinical assessment of 103 patients (166 hips) in whom the arthroplasty was still functioning showed that 94% of hips had minimal pain or none. We conclude that in young patients cemented total hip replacement is a good procedure for those with rheumatoid arthritis but that the results are much less reliable in those with osteoarthritis

In 16 patients we used uncemented Lord prostheses at revision operations for aggressive granulomatosis after cemented hip arthroplasties; in 12 bone grafts also were used. In 13 hips the granulomatous lesions were multifocal, and in one the acetabular component was involved. There was no evidence of infection in any case: all the patients had normal ESR and CRP levels. The revision operation was performed on average 9.4 years after the primary replacement; the mean age at revision was 64 years. On radiographs, the bone around the prosthesis had consolidated by an average of 16 months. At follow-up, two to six years later (mean 3.5 years) there had been no recurrences, nine patients had an excellent Mayo hip score, five were good and two fair

Total hip replacement was performed in 27 hips of patients who had sickle cell anaemia with avascular necrosis of the femoral head. The disease was bilateral in 11 patients. Considerable medical problems were encountered although most of the patients had exchange transfusion before surgery (86%), which prevented postoperative sickle cell crises in all but two cases. At the primary operation hard sclerotic bone was seen in nine femora with complete obliteration of the femoral canal. There were four femoral fractures, three following perforation of the shaft due to this hard bone. There was a very high morbidity due to loosening in both cemented and uncemented prostheses. With a rate of 59% over a cumulative 5.5 year period, revision was being performed at an average of only 43 months. Surgeons should be aware of these problems

In this prospective, randomised study, we have compared the wear rate of cemented, acetabular polyethylene cups articulating with either a 22 mm or a 32 mm cobalt-chromium head. We evaluated 89 patients who had a total of 484 radiographs. The mean follow-up period was 71.4 months (SD 29.1). All the radiographs were digitised and electronically measured. The linear wear rate was significantly higher during the first two years and decreased after this period to a constant value. We suggest that this is partly due to a ‘run-in’ process caused by irregularities between surfaces of the cup and head and an initial plastic deformation of the polyethylene. The mean volumetric wear was 120.3 mm. 3. /year for the 32 mm head, which was significantly higher than the 41.5 mm. 3. /year for the 22 mm heads. The mean linear wear rate was not significantly different. We were, however, unable to find radiological signs of osteolysis in the patients who had higher wear rates

Implants of solid sintered hydroxyapatite form very tight bonds with living bone, but are susceptible to fatigue failure. This problem can be overcome by using plasma-sprayed apatite coatings on titanium implants. A very strong bond is formed between bone and this composite material; this was studied in canine bone with plug implants, avoiding any mechanical retention. Mechanical testing showed an interface shear strength at six weeks of 49 MPa with a maximum of 64 MPa after six months. There was histological evidence of direct bonding between the apatite coating and living bone while uncoated control plugs were easily extracted. The results indicate that apatite-coated implants can form a chemical fixation with a strength comparable to that of cortical bone itself. This fixation is far stronger than that provided by current cemented or uncemented fixation techniques

Aims

The aim of this retrospective multicentre study was to evaluate mid-term results of the operative treatment of Monteggia-like lesions and to determine the prognostic factors that influence the clinical and radiological outcome.

The results of conventional hip replacement in young patients with osteoarthritis have not been encouraging even with improvements in the techniques of fixation and in the bearing surfaces. Modern metal-on-metal hip resurfacing was introduced as a less invasive method of joint reconstruction for this particular group. This is a series of 446 hip resurfacings (384 patients) performed by one of the authors (DJWM) using cemented femoral components and hydroxyapatite-coated uncemented acetabular components with a maximum follow-up of 8.2 years (mean 3.3). Their survival rate, Oxford hip scores and activity levels are reviewed. Six patients died due to unrelated causes. There was one revision (0.02%) out of 440 hips. The mean Oxford score of the surviving 439 hips is 13.5. None of the patients were told to change their activities at work or leisure; 31% of the men with unilateral resurfacings and 28% with bilateral resurfacings were involved in jobs that they considered heavy or moderately heavy; 92% of men with unilateral hip resurfacings and 87% of the whole group participate in leisure-time sporting activity. The extremely low rate of failure in spite of the resumption of high level occupational and leisure activities provides early evidence of the suitability of this procedure for young and active patients with arthritis

Glass ionomer cement (Ionocem) was developed for use in bone surgery and is reported to be notably biocompatible. Between 1991 and 1994 we performed revision operations for aseptic loosening of arthroplasties of the hip on 45 patients using this material in its granulate form (Ionogran) mixed with homologous bone as a bone substitute. Of these 45 patients, 42 were followed up for a mean of 42 months. Early reloosening of the acetabular component has occurred in ten after a mean of 30 months. Histological examination showed large deposits of aluminium in the adjacent connective tissue and bone. Osteoblastic function and bone mineralisation were clearly inhibited. The serum levels of aluminium were also increased. The toxic damage at the bone interface caused by high local levels of aluminium must be seen as an important factor in the high rate of early reloosening. Our findings cast doubt on the biocompatibility of this material and we do not recommend continuation of its further use in orthopaedic surgery

Inadequate bone stock is often found in revision surgery of femoral components of total knee replacements. Our aim was to test the hypothesis that these remodelling patterns can be explained by stress shielding, and that prosthetic bonding characteristics affect maintenance of bone mass. We made a three-dimensional finite-element model of an average male femur with a cemented femoral knee component. This model was integrated with iterative remodelling procedures. Two extreme prosthetic bonding conditions were analysed and gradual changes in bone density were calculated. The long-term bone loss under the femoral knee component resembled clinical findings which confirms the hypothesis that stress shielding can cause distal femoral bone loss. Our study predicts, contrary to clinical findings, that an equilibrium situation is not reached after two years, but that bone resorption may continue. This hidden bone loss may be so drastic that large reconstructions are needed at the time of revision

Aim

It has been suggested that the use of a pilot-hole may reduce the risk of fracture to the lateral cortex. Therefore the purpose of this study was to determine the effect of a pilot hole on the strains and occurrence of fractures at the lateral cortex during the opening of a high tibial osteotomy (HTO) and post-surgery loading.

We have compared the survival of two hydroxyapatite (HA)-coated cups, 1208 Atoll hemispheric and 2641 Tropic threaded, with cemented Charnley all-polyethylene cups (16 021) using the Cox regression model. The Tropic cup used in combination with an alumina ceramic femoral head, had good results, similar to those of the Charnley cup. When used in combination with a stainless-steel head, however, the risk of revision beyond four years was increased 3.4 times for the Tropic cup compared with the Charnley cup (p < 0.001). Over the same period, the Atoll cup had an increased risk of revision of 3.8 times when used with the alumina heads (p < 0.001) and an increased risk of 6.1 times when used with stainless-steel heads (p < 0.001). Revision because of wear and osteolysis was more common with both types of HA-coated cup than with the Charnley cup. The rate of revision of the Atoll cup because of aseptic loosening was also increased. We found that HA-coated cups did not perform better than the Charnley cup

We reviewed 64 patients in whom 66 acetabula had been reconstructed with either the Muller ring (46) or the Burch-Schneider anti-protrusio cage (20) at a mean follow-up of five years. Five hips had been revised a second time for loosening, all after a Muller ring had been used for a medial segmental defect (2), ungrafted cavitary defects (2) or after resorption of a block graft (1). The use of bone grafts with the implants reduced the incidence of failure from 13% to 6% and of circumferential radiolucent lines at the bone-implant interface from 39% to 2%. The Muller ring is indicated for acetabula with isolated peripheral segmental defects or cavitary defects confined to one or two sectors. The Burch-Schneider cage should be used for medial segmental defects, extensive cavitary defects and combined deficiencies. Defects should be reconstituted with bone graft rather than cement