Twenty-year results of McKee-Farrar versus Charnley prosthesis.

The results of 107 consecutive McKee-Farrar and 70 Charnley total hip arthroplasties performed in 169 patients between 1975 and 1976 are reviewed. At an average followup of 20 years (range, 19-21 years), 29 patients with 20 McKee-Farrar and 11 Charnley prostheses were available for clinical and radiologic evaluation; 102 patients (107 hips) had died, 3 patients were lost to followup, and 5 patients (6 hips) were unavailable for review because of medical problems. There were 5 revisions for sepsis and 1 Girdlestone procedure for recurrent dislocation. Sixteen McKee-Farrar and 8 Charnley prostheses were revised for aseptic loosening, giving a 20-year aseptic probability of survival of 77% and 73%, respectively. Radiographic signs of loosening were present in 52% of the surviving prostheses. Clinical scores showed weak correlation with the radiographic loosening in both groups, and 18 McKee-Farrar and 8 Charnley prostheses were still considered satisfactory by the patients. The mean annual linear polyethylene wear was 0.12 mm. Osteolytic lesions were observed in association with 2 McKee-Farrar and 5 Charnley prostheses in surviving hips. The long term results of the McKee-Farrar prosthesis are comparable with those of the low friction arthroplasty in this series. Wear of the polyethylene bearing and accumulation of polyethylene particles in the periprosthetic tissue may become an increasing problem. Second generation all metal implants seem to be worth considering in patients with long life expectancy.

Stem loosening more common with ITH than Lubinus prosthesis. A 5-year clinical and radiographic follow-up of 142 patients.

Out of a consecutive series of 169 cemented total hip arthroplasties, 77 Lubinus SP 2 and 65 ITH prostheses, were followed-up after 5 years with clinical and radiographic assessments. Radiolucencies were commoner around the ITH titanium stem than around the Lubinus cobalt-chrome stem. 6 of the ITH stems were considered as definitely loose, as compared to none of the Lubinus stems. Hitherto, 5 patients in the ITH group have had revisions and 2 need revision because of loosening. The poorer performance of the cemented ITH stem may be due to an unfavorable combination of design and material properties.

Effect of diclofenac on fixation of hydroxyapatite-coated implants. An experimental study.

We studied the effect of non-steroidal anti-inflammatory drugs on the fixation of hydroxyapatite-coated implants. Cylindrical plugs of pure titanium, coated with hydroxyapatite (HA), were inserted into both femora of 10 adult rabbits, 5 of which received 7 daily doses of 30 mg diclofenac. Three weeks after implantation the interface strengths were measured by the pull-out test. The mean peak force for the diclofenac-treated group was 290 +/- 57 N compared with 369 +/- 37 N for the control group (p < 0.025). We conclude that the inhibitory effect of diclofenac on bone repair is not neutralised by HA-coating of an implant.

Tc-scintimetry in 56 cementless hip arthroplasties. A prospective, randomized comparison of two femoral components.

In a prospective, randomized study of cementless total hip arthroplasties, radionuclide images as well as radiographs were obtained at 6, 12, and 36 months postoperatively. The femoral component was porous-coated, rigid in 28 patients and smooth, isoelastic in 28. The radionuclide uptake was quantified in the regions of interest and correlated to the non-operated side. Among prostheses considered to be stable 3 years after surgery, the activity had normalized in the calcar region. The uptake was also reduced below the tip of the prostheses, but the activity was still 50 percent increased compared to the non-operated side. The isoelastic prosthesis showed less reduction of activity below the tip than the rigid prosthesis. Proximally, the isoelastic prosthesis showed no reduction of activity, whereas the rigid prosthesis had normalized the uptake at the 3-year control. A high rate of non-stable fixation was observed for the flexible prosthesis at the radiographic assessment, which may have contributed to the increased radionuclide activity. Sequential scintimetry may be used as a complement to the radiographic evaluation of the femoral component of the hip prosthesis.

Revision of infected hip replacement. Two-stage procedure with a temporary gentamicin spacer.

We revised 5 infected totally-replaced hips in 2 stages. At the first operation a gentamicin-loaded modelled cement spacer was inserted, and the definitive prosthesis was inserted 3-8 weeks later. 9-24 months after the last operation, there was a recurrent infection in 1 case. 2 of the patients could walk in the interval.

Design and testing of a flexible hip prosthesis.

A prosthesis with flexibility and optimal proximal fit was constructed in titanium alloy. The aim was to create the same elasticity as in the femoral shaft. Distally it was cylindrical with slots in the stem and a spacer made of polymer was placed in the slots. The proximal part of the prosthesis was wedge-shaped in both planes and a collar with a conical contact surface to bone was used. Pure titanium was plasma sprayed on the upper part as well as underneath the collar allowing bony ingrowth. A test jig was constructed and 10 million cycles with 4000 N loading was planned. The prosthesis broke after 600 000 cycles and it was a typical fatigue failure. A commercially available flexible prosthesis was tested as a reference and broke after 29 000 cycles. It is concluded that construction of a flexible hip prosthesis using metal with reasonable security against fatigue failure breakage is difficult, and we are somewhat doubtful if it is possible.

A prospective comparison of Butel and PCA hip arthroplasty.

We compared two cementless femoral components, the 'isoelastic' Butel stem and the more rigid PCA design, in a randomised, prospective study of 56 patients with a mean follow-up of 4 years (2 to 5). Patients were matched in 28 pairs, and one of each pair was treated with each femoral component. The isoelastic stem gave fewer signs of stress shielding radiologically, but both the Harris hip score and the visual analogue pain scale showed significantly inferior results at the two-year and three-year follow-up. The overall failure rates for the femoral components were 43% for the Butel and 11% for the PCA. These results contrast with those of earlier experimental and clinical studies, in which isoelastic properties appeared to be advantageous. This review emphasises the importance of controlled studies before an altered or new design of prosthesis is released on to the market for general use.

Renal function after hip arthroplasty and isoxazolylpenicillin prophylaxis.

Two different isoxazolylpenicillins (cloxacillin and dicloxacillin) were compared regarding impairment of renal function after total hip arthroplasty. 85 patients received dicloxacillin and 93 patients received cloxacillin as antibiotic prophylaxis. A total dose of 6 grams was given during a 36-hour period in doses of 1 gram pre-, per- and postoperatively. Creatinine in serum and beta 2-microglobulin in serum and urine were determined preoperatively and 2, 4, and 10 days after the operation. The dicloxacillin-treated patients had an increase in creatinine and beta 2-microglobulin in serum that was not seen in the cloxacillin group. The increase indicates a transient injury in the process of glomerular filtration. Although the increase was temporary and subclinical, a dose reduction is nevertheless recommended for older patients.

Heterotopic bone formation prevented by diclofenac. Prospective study of 100 hip arthroplasties.

A double-blind, placebo-controlled study was done on the influence of diclofenac, a nonsteroidal anti-inflammatory drug, on heterotopic bone formation after total hip arthroplasty. Totally, 100 operations were involved, and a follow-up was performed after 1 year. There were no cases of substantial bone formation in the treated group versus two thirds of the cases in the placebo group, and some of these had pain. Because side effects of treatment with diclofenac are few and mild, we advocate prophylactic use of this drug.

Risks, benefits and economic consequences of total hip arthroplasty in an aged population.

An attempt was made to evaluate risks, benefits and costs of total hip replacement in patients over 80 years. Forty consecutive replacements in 37 patients were analysed and the results were compared to a younger population (36 patients) concerning complications and duration of hospitalization. The elderly group was reexamined two years postoperatively to assess the outcome. There was a significantly prolonged stay in hospital/long-term care for the octogenarians, 31.1 days compared to 13.6 for the younger group, as well as an increased risk for complications. Eleven patients had 18 different complications (11/40; 27.5%) in contrast to 2 complications in 2 patients (2/36; 5.6%) in the younger population. Quality of life was increased in terms of pain relief and there was moderate improvement in function. For the elderly, the community expenses for welfare services were not found to be reduced after the intervention. It is concluded that the observed improvement of quality of life has to be balanced against the increased risks and costs for this group.

A comparative study between McKee-Farrar and Charnley arthroplasty with long-term follow-up periods.

One hundred seventy-seven consecutive total hip arthroplasties on 169 patients, 107 with a McKee-Farrar prosthesis and 70 with a Charnley low-friction arthroplasty, were followed in a prospective study. Fifty-five patients (31%) representing 55 hips died during the study period. Four (2%), two McKee-Farrar and two Charnley, were lost to follow-up study. The remaining 55 McKee-Farrar and 41 Charnley hips were evaluated after a mean follow-up period of 11.5 years (range, 10.1-13.5 years). Twenty-two (12%) of the hips had been revised. A survival study was performed and the two techniques were compared with regard to walking ability, Harris hip score, and radiologic assessment. No major differences were observed. The mean annual revision rate in this series was 1.3%. Walking distance increased from 200 m before operation to 2,000 m 1 year after operation and then remained constant during the observation time. The results, using the Harris hip score, were good or excellent (greater than 80 points) in 47%. Thirty hips (32%) showed signs of prosthetic loosening; 17 of these caused pain on weightbearing occasionally or regularly and 13 caused no pain at all.

A simplified roentgen stereophotogrammetric method. Analysis of small movements between the prosthetic stem and the femur after total hip replacement.

A simplified roentgen stereophotogrammetric method is described. It is based on the use of a 50 mm thick reference plate consisting of a carbon-fibre-reinforced polyester box. The patient is placed directly on this box, which makes the methods less cumbersome and more suitable for routine use. The method has been tested in a model experiment designed for detecting small movements between femur and prosthesis at an early stage after total hip replacement. The head and two hemispheres on the prosthesis and three small tantalum balls inserted in the femur serve as reference points. The model experiment now reported shows that the method has acceptable precision.

Calcar unloading after hip replacement. A cadaver study of femoral stem designs.

The load transfer from the pelvis to the femur in extension and 45 degrees of flexion was examined in normal hips and hips replaced with 11 different prostheses. The cadaver specimens were mounted in a jig and the load patterns recorded by strain gauges attached to critical points determined in a pilot study, with the aid of a photoelastic coating. All the prostheses except an "isoelastic" model showed marked reduction of strain in the calcar area compared with the normal femur. A collar increased the strain to about 40 per cent of normal. No significant difference was noted between curved and straight stems. There were no major differences between the prostheses on loading in flexion.

Total hip replacement comparison between the McKee-Farrar and Charnley prostheses in a 5-year follow-up study.

In a prospective study, 177 patients who underwent total hip replacement by the McKee-Farrar or Charnley techniques were followed up for 5 years with yearly clinical examinations, walking tests, and X-rays. The findings concerning pain, walking ability, and complications were satisfactory and similar to the inventors' own 5-year results. Comparison between the two techniques disclosed no major differences. Over 90% of the patients were free from pain; the infection rate was 3.4% and the loosening rate 6%. A walking test showed marked increase in speed over the first few years and a slight decrease after the third year. Our findings do not support the hypothesis that the metal-on-metal prosthesis is clinically inferior to the metal-on-polyethylene prosthesis.

Loosening 5 years after total hip replacement--a radiological study of the McKee-Farrar and Charnley prostheses.

In a prospective study, 138 patients who underwent total hip replacement by the McKee-Farrar or the Charnley technique were monitored yearly for 5 years by X-ray. Six variables were measured on anteroposterior and lateral projections to describe the position of the prosthesis. Lateral opening greater than 50 degrees and cover of the acetabular cup less than 1.5 cm correlated with an increased cup-loosening rate: 71% (98 of 138) were loose at the 5-year follow-up. However, only about one-third of all cup loosenings in the present series can be explained by nonoptimal position of the prosthesis. No significant difference emerged concerning loosening rate between the McKee-Farrar and the Charnley prostheses.