During revision THR, the surgery is often difficult and compromised due to lack of patient's bone especially in the pelvis. Any extra bone in the acetabulum is expected to be of advantage to the patient and the surgeon. The aim of this study was to see if preservation of medial acetabular osteophyte in uncemented total hip replacement had any adverse effect on the prosthesis survival or patient satisfaction. Conventional acetabular preparation involves reaming down to the true floor. This not only medialises the centre of rotation of the hip but also reduces the acetabular offset. In contrast the main surgeon preserved the acetabular offset by preserving some osteophytic bone between the true floor of the acetabulum and the acetabular cup. This is achieved by reaming the acetabular cavity conservatively while achieving secure primary fixation of the prosthesis. We report the outcome of a single surgeon series of such cases. The endpoint was assessed as the need for revision of the acetabular cup. A total of 106 consecutive patients were identified who underwent uncemented THR from 2005 to 2010. The medial osteophyte was measured on immediate post-operative x-rays, from the “teardrop” to the nearest point of the acetabular cup, by 3 surgeons (one consultant and 2 registrars). The patients were contacted for a telephone interview and their clinical notes, including x-rays, were reviewed. Outcome was available for 79 patients. 74 patients were available for follow-up and 5 patients died unrelated to THR. Average follow-up was for 8.3 years (range 5.5–10.8). Average age was 62 years. The average medial osteophyte was 1.98 mm (range 0–14mm). One patient had late infection and one had dislocation. There was not a single failure of the acetabular component. The patient satisfaction was high at 8.8 out of 10. Preservation of medial osteophyte in the acetabulum whilst doing uncemented THR has the advantage of retaining the patient's own bone stock which can be of great advantage to the surgeon as well as the patient should revision THR be required in future. Our study has shown that this can be achieved without compromising the survival of the prosthesis or the patient satisfaction. This technique may increase the range of motion of the hip by reducing the risk of bony or soft tissue impingement, and also reduce the risk of dislocation. Furthermore, not recreating the native centre of rotation of the hip does not seem to have any adverse effect for the patients, who are very happy with the outcome. We recommend that whilst doing uncemented THR, the acetabulum should not be reamed to the true floor as has been the conventional teaching, but attempt should be made to preserve some medial osteophyte where possible, at the same ensuring that good primary fixation of the cup is achieved. This is to give the patient and surgeon the advantage of extra available bone should revision surgery be required in the future

We measured the levels of cobalt and chromium in the serum in three groups of patients after uncemented porous-coated arthroplasty. Group 1 consisted of 14 consecutive patients undergoing revision for aseptic loosening. Group 2 comprised 14 matched patients in whom the arthroplasty was stable and group 3 was 14 similarly matched patients with arthritis awaiting hip replacement. Specimens were analysed using atomic absorption spectrophotometry.

Aseptic loosening of a component resulted in a significant elevation of serum cobalt (p < 0.05), but not of serum chromium. The relative risk of a component being loose, if the patient had a serum cobalt greater than 9.0 nmol/l, was 2.8.

Background

Although the tribological characteristics are excellent, cup fixation has been one of the limitations in alumina-on-alumina total hip replacement (THR), so different types of materials and surfaces have been developing. We analysed the clinical and radiological outcome of two different uncemented cups for the same alumina-on-alumina THR.

Although cemented fixation provides excellent results in primary total hip replacement (THR), particularly in patients older than 75 years, uncemented implants are most commonly used nowadays. We compare the rate of complications, clinical and radiological results of three different designs over 75-years-old patients.

433 hips implanted in patients over 75 years old were identified from our Local Joint Registry. Group A consisted of 139 tapered cemented hips, group B of 140 tapered grit-blasted uncemented hips and group C of 154 tapered porous-coated uncemented hips. A 28 mm femoral head size on polyethylene was used in all cases. The mean age was greater in group A and the physical activity level according to Devane was lower in this group (p<0.001 for both variables). Primary osteoarthritis was the most frequent diagnoses in all groups. The radiological acetabular shape was similar according to Dorr, however, an osteopenic-cylindrical femur was most frequently observed in group A (p<0.001). The pre- and post-operative clinical results were evaluated according to the Merle-D'Aubigne and Postel scale. Radiological cup position was assessed, including hip rotation centre distance according to Ranawat and cup anteversion according to Widmer. We also evaluated the lever arm and height of the greater trochanter distances and the stem position. Kaplan-Meier analysis was done for revision for any cause and loosening.

The hip rotation centre distance was greater and the height of the greater trochanter was lower in group B (p=0.003, p<0.001, respectively). The lever arm distance was lower in group C (p<0.001). A varus stem position was more frequently observed in group B (p<0.001). There were no intra- or post-operative fractures in group A, although there were five intra-operative fractures in the other groups plus two post-operative fractures in group B and four in group C. The rate of dislocation was similar among groups and was the most frequent cause for revision surgery (8 hips for the whole series). The mean post-operative clinical score improved in all groups. The overall survival rate for revision for any cause at 120 months was 88.4% (95% CI 78.8–98), being 97.8% (95% CI 95.2–100) for group A, 81.8% (95% CI 64.8–98.8) for group B and 95.3% (95% CI 91.1–99.6) for group C (log Rank: 0.416). Five hips were revised for loosening. The overall survival rate for loosening at 120 months was 91.9% (95% CI 81.7–100), being 99.2%(95% CI 97.6–100) for group A, 85.5 (95% CI 69.9 −100) for group B and 100% for group C (Log Rank 0.093).

Despite a more osteopenic bone in the cemented group, the rate of peri-prosthetic fractures was higher after uncemented THR in patients older than 75 years. Although the overall outcome is good with both types of fixation, the post-operative reconstruction of the hip, which might be more reliable after cemented fixation, may affect the rate of complications in this population.

Introduction. Durable bone fixation of uncemented porous-coated acetabular cups can be observed at a long-term, however, polyethylene (PE) wear and osteolysis may affect survivorship. Accurate wear measurements correlated with clinical data may offer unique research information of clinical interest about this highly debated issue. Objetive. We assessed the clinical and radiological outcome of a single uncemented total hip replacement (THR) system after twenty years analysing polyethylene wear and the appearance of osteolysis. Materials and Methods. 82 hips implanted between 1992 and 1995 were prospectively evaluated. The mean follow-up was 20.6 years (range, 18 to 23). A hemispherical porous-coated acetabular cup matched to a proximally hydroxyapatite-coated anatomic stem and a 28 mm standard PE liner, sterilised by gamma irradiation in air, was used in all hips. Radiological position and the possible appearance of loosening and osteolysis were recorded over time. Penetration of the prosthetic head into the liner was measured by the Roentgen Monographic Analysis (ROMAN) Tool at 6 weeks, 6 months, one year and yearly thereafter. Results. Six cups were revised due to wear and four due to late dislocation. All cups were radiographically well-fixed and all stems showed radiographic ingrowth. Six un-revised hips showed osteolysis on the acetabular side and two on the proximal femoral side. Creep at one year was 0.30 (±0.23) mm. Mean total femoral head penetration was 1.23 mm at 10 years, 1.52 mm at 15 years and 1.92 mm at 23 years. Overall mean wear was 0.12 (± 0.1) mm/year and 0.09 (±0.06) mm/year after the creep period. Mean wear was 0.08 (± 0.06) mm/year in hips without osteolysis and 0.14 (±0.03) mm/year in revised hips or with osteolysis (p<0.001). Conclusions. Although continued durable fixation can be observed with a porous-coated cups and a proximally hydroxyapatite-coated anatomic stem, true wear continues to increase at a constant rate over time. PE wear remains as the main reason for revision surgery and osteolysis in uncemented THR and does not stop after twenty years

Objectives

An experimental rabbit model was used to test the null hypothesis, that there is no difference in new bone formation around uncoated titanium discs compared with coated titanium discs when implanted into the muscles of rabbits.