A study of the natural history and aetiology of deep vein thrombosis in 499 patients after total hip replacement is presented. Deep vein thrombosis was diagnosed by scanning the leg for 125Iodine-labelled fibrinogen for a period of 14 to 18 days and by ascending phlebography. It has been shown that deep vein thrombosis occurs ater than in patients who have undergone abdominal operations, and the risk period is longer. The peak of onset of thrombosis is on the fourth day after the hip replacement. Attempts at prophylaxis using subcutaneous heparin or intermittent pneumatic compression of the calves delay the appearance of thrombosis. Analysis of possible aetiology factors shows that the age of the patient, the degenerative disease of the hip, the surgical approach, and under-transfusion of blood, all have a significant effect on the incidence of thrombosis

Roentgen stereophotogrammetry was used to measure the migration of the centre of the femoral head in 84 cemented Lubinus SP I hip arthroplasties (58 primary operations, 26 revisions). Four to seven years later, seven femoral components had been revised because of painful loosening. These implants showed greater subsidence, medial migration and posterior migration during the first two postoperative years than did the hips which had not been revised. Six months after operation, subsidence of more than 0.33 mm combined with a total migration of more than 0.85 mm predicted an increased risk of subsequent revision; the amount of subsidence at two years was an even better predictor. The probability of revision was greater than 50% if the subsidence at two years was 1.2 mm or more

Aims

Cardiac magnetic resonance (CMR) was used to assess whether cardiac function or tissue composition was affected in patients with well-functioning metal-on-metal hip resurfacing arthroplasties (MoMHRA) when compared with a group of controls, and to assess if metal ion levels correlated with any of the functional or structural parameters studied.

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

Of 142 Chiari pelvic osteotomies for osteoarthritis in dysplastic hips, most performed by Chiari himself, we were able to review 82 and obtain information about 18 by questionnaire. All patients were over 30 years of age at operation; follow-up averaged 15.5 years. Twenty hips had undergone secondary total hip replacement. The outcome was good in 75%, fair in 9% and poor in 16%. High osteotomies all gave good results, and the result also depended on adequate medialisation. Statistics were worse for patients over 44 years of age at the time of operation. For osteoarthritis secondary to hip dysplasia, the Chiari pelvic osteotomy is an alternative procedure to early hip replacement. In contrast to intertrochanteric osteotomy, it has the advantage of facilitating the implantation of an acetabular prosthesis should arthroplasty become necessary at a later stage

During the years 1971 to 1975, 378 Charnley low-friction arthroplasties of the hip were performed on 278 patients with rheumatoid arthritis. The average age at operation was thirty-nine years. The follow-up time ranged from one to six years (mean two and a half years). Forty per cent of patients were receiving steroids at the time of operation. The most common complications were loosening of the prosthesis (3.4%), perforation of the femoral cortex and fracture. Deep infection occurred in 0.7%, dislocation in 0.7%, and thromboembolic episodes in 1.3%. Ninety-five per cent of patients were free of pain at follow-up compared to 84% who were severely handicapped by pain before operation. In addition, the increased mobility in 98.5% of patients and their improved independence makes hip replacement a recommendable procedure in these patients

We studied the pattern of . 99m. Tc-methylene diphosphonate uptake around uncemented femoral components in 44 asymptomatic hip arthroplasties, performing isotope scans at intervals from 4 to 48 months after operation. We used phase-III images obtained with a high-resolution gamma camera and measured the activity in various zones using a specially designed computer program. The components studied at 4, 6, 9 and 12 months were coated with hydroxyapatite (HA) and those studied at 18, 24, 36 and 48 months were not coated. We found a statistically significant fall in activity between four and six months around HA-coated prostheses in all five femoral periprosthetic zones. After six months activity was relatively uniform, but remained higher than that in normal femoral bone at 48 months in non-coated prostheses. We discuss the application of these patterns in the evaluation of painful cementless hip arthroplasties

We measured polyethylene wear in 231 porous-coated uncemented acetabular cups. We divided the hips into two groups according to the fixation of the femoral component, by cementing (n = 97) or press-fit (n = 134). Follow-up was from three to five years. The patients in two sub-groups were matched for weight, diagnosis, sex, age and length of follow-up. The linear wear rate of cups articulated with uncemented femoral components (0.22 mm/year) was significantly higher than the wear rate (0.15 mm/year) of cups articulated within cemented femoral components (p < 0.05). These results can be compared with previously reported wear rates of 0.08 mm/year for cemented all-polyethylene cups and 0.11 mm/year for cemented metal-backed cups. The higher wear rates of uncemented arthroplasties could jeopardize the long-term results of this type of hip replacement

Fifty-four cobalt-chrome alloy femoral heads were retrieved at revision surgery or at post-mortem; 23 came from uncemented, eight from hybrid and 23 from cemented hip arthroplasties. The uncemented and hybrid implants had porous coating, metal backing and modular femoral heads; with one exception none of the cemented implants had any of these. Twenty-five of the 31 heads from uncemented and hybrid arthroplasties, and 11 of the 23 heads from cemented arthroplasties showed surface damage involving more than 25% of the surface. Scanning electron microscopy revealed multidirectional fine scratches 1 micron to 10 microns in depth and width which appeared to have been made by fine, hard particles. There was a higher rate of such damage in the uncemented and hybrid arthroplasties than in the cemented implants, suggesting that the abrasive particles were mainly released from the metal, rather than from the cement or polyethylene components of the implants

We report the 12 to 74 month results of our mark I saddle prosthesis after its use as a salvage device for gross loss of pelvic bone stock in 76 patients with failed hip arthroplasties. The implant transmits load between iliac bone and bare polish chrome-cobalt. Our clinical and radiological results indicate that a useful and stable articulation can be achieved in most cases, provided that continued deep infection can be avoided. The appearance of radiological sclerosis at the bearing site in successful cases seems to indicate that significant late migration will not occur. Based on our experience with the mark I prosthesis we have designed and developed a mark II model which has freedom of axial rotation of the saddle. Our early results in 40 cases show a significant improvement over the results which could have been predicted for the mark I device

The effect of hypobaric spinal anaesthesia or narcotic-halothane-relaxant general anaesthesia on the incidence of postoperative deep vein thrombosis was studied in 140 elective total hip replacements in a prospective randomised manner. Deep vein thrombosis was diagnosed using impedance plethysmography and the 125I fibrinogen uptake test, combined, in selected cases, with ascending contrast venography. The overall incidence of deep vein thrombosis was 20%. Nine patients (13%) developed deep vein thrombosis in the spinal group and nineteen (27%) in the general anaesthetic group (p less than 0.05). The incidences of proximal thrombosis and of bilateral thrombi were also less with spinal anaesthesia than with general anaesthesia. It is concluded that spinal anaesthesia reduces the risks of postoperative thromboembolism in hip replacement surgery. The presence of varicose veins, being a non-smoker and having a low body mass index were associated with an increased incidence of deep vein thrombosis

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

The purpose of this study was to establish if the Bateman prosthesis functions as a bipolar device moving primarily at the inner metal-on-polyethylene bearing as originally proposed, or as a unipolar hemiarthroplasty moving at the outer metal-on-cartilage surface as has recently been suggested. One hundred hips were examined at one year follow-up; 78 were examined again at two to four years. The replacement was performed for arthritis in 76 hips and for femoral neck fracture in 24. Movement was assessed both with and without weight-bearing. In 80% of the arthritis group the prosthesis functioned as a bipolar hip replacement with movement occurring primarily at the inner metal-on-polyethylene surface. By contrast, in 75% of the fracture group the prosthesis functioned largely as a unipolar device with movement occurring primarily at the outer metal-on-cartilage surface. In all cases examined serially the movement pattern was the same at two to four years as it has been at one year. Clearly, the action of the prosthesis depends on the condition of the acetabular cartilage

All surgical operations have the potential for contamination, and the equipment used can harbour bacteria. We collected samples from 100 elective primary hip and knee arthroplasties. These showed rates of contamination of 11.4% for the sucker tips, 14.5% for light handles, 9.4% for skin blades and 3.2% for the inside blades used during surgery; 28.7% of gloves used for preparation were also contaminated. Of the samples taken from the collection bags used during hip arthroplasty, 20% grew bacteria, which represents a significant microbial reservoir. Also, 17% of theatre gowns were contaminated at the end of the operation. Contamination was found in 10% of the needles used during closure of the fascia. Overall, 76% of the organisms grown were coagulase-negative staphylococcus. A total of 63% of operations showed contamination in the field of operation. Some changes in practice are suggested. Follow-up for a minimum of two years revealed one deep infection but the organism was not identified as a contaminant. These data provide a baseline for studying the bacteriology of the surgery of revision arthroplasty

Objectives

Prosthetic joint infection (PJI) diagnosis is a major challenge in orthopaedics, and no reliable parameters have been established for accurate, preoperative predictions in the differential diagnosis of aseptic loosening or PJI. This study surveyed factors in synovial fluid (SF) for improving PJI diagnosis.

Aims

Single-stage revision is not widely pursued due to restrictive inclusion criteria. In this study, we evaluated the results of single-stage revision of chronically infected total hip arthroplasty (THA) using broad inclusion criteria and cementless implants.

A total of 110 total knee replacements (TKRs) was randomised to receive either a cemented or an uncemented prosthesis. Postoperative venography at five to seven days was used to compare the prevalence, site and size of deep-vein thrombosis (DVT). We also compared the findings with those of postoperative venography in a group of patients with cemented total hip replacements (THRs). The total prevalence of DVT was significantly greater after uncemented (81%) than after cemented TKR (55%). Both knee groups had a significantly higher prevalence of DVT than in cemented hip replacements (32%). We found no difference in the proportion with proximal DVT in the three groups (14%, 15% and 16%). The median length of the thrombi was significantly greater after cemented (26.5 cm) than after uncemented TKR (11 cm) or after cemented THR (7 cm). This difference was mainly due to greater lengths of distal rather than proximal thrombi. We conclude that the use of cement may affect the formation of DVT after joint replacement, but does not appear to lead to an increased incidence

We have developed a new drug delivery system using porous apatite-wollastonite glass ceramic (A-W GC) to treat osteomyelitis. A-W GC (porosity, 70% and 20% to 30%), or porous hydroxyapatite (HA) blocks (porosity 35% to 48%) used as controls, were soaked in mixtures of two antibiotics, isepamicin sulphate (ISP) and cefmetazole (CMZ) under high vacuum. We evaluated the release concentrations of the antibiotics from the blocks. The bactericidal concentration of ISP from A-W GC was maintained for more than 42 days, but that from HA decreased to below the detection limit after 28 days. The concentrations of CMZ from both materials were lower than those of ISP. An in vivo study using rabbit femora showed that an osseous concentration of ISP was maintained at eight weeks after implantation. Osteoconduction of the A-W GC block was good. Four patients with infected hip arthroplasties and one with osteomyelitis of the tibia have been treated with the new delivery system with excellent results