Results of a single total knee prosthesis compared with multiple joint replacement in the lower limb.

We present the clinical results of total knee replacement (TKR) in 133 patients who had two or more major joints of the lower limbs replaced, and compare them to the outcome in 406 patients with an isolated TKR. 383 patients had osteoarthritis (OA) and 136 had rheumatoid arthritis (RA) and these were assessed separately. A meniscal bearing prosthesis was used. The functional score was high and there was no statistically significant difference in the incidence of complications between the two groups.

Reduction of polyethylene in a congruent meniscal knee prosthesis. Experimental and clinical studies.

Polyethylene wear was assessed in the Rotaglide congruent meniscal bearing total knee prosthesis and a partial congruent total knee prosthesis with fixed bearing polyethylene tibial platform and a posterior stabilizer mechanism. A special wear test rig was used to test the 2 prostheses under compression load of 2960 N/mm2 (about 4 times the average body weight) and continuous 0 degree-70 degrees flexion-extension motion at the rate of 1 cycle per second. The most remarkable finding was the lack of measurable wear on the Rotaglide meniscal bearing up to 3.5 million cycles, while the other prosthesis began to show wear from the first million cycles and progressed to 0.38 mm at about 3.5 million cycles. At 11 million cycles (about 20 years of life), the Rotaglide showed penetration wear of 0.35 mm compared to 2.1 mm in the other prosthesis. In 7 meniscal bearings, retrieved either at postmortem (2) or at reoperation (5), no measurable penetration wear was observed after 3 years of implantation. Only 1 prosthesis obtained 5 years after implantation showed 0.23 mm penetration wear or about 0.05 mm per year. These findings strongly suggest that the use of congruent meniscal bearing prosthesis can reduce the polyethylene wear in total knee replacement.

The Rotaglide total knee arthroplasty. Prosthesis design and early results.

The Rotaglide knee (Cozim Medical, UK) is a three-part knee containing a mobile polyethylene meniscal platform, imparting reduced loosening forces to the tibia. The femoral component design provides a high degree of congruency throughout the range of motion from 0 degree to 110 degrees, and both femoral and tibial components ensure minimal bone removal. The system is versatile, including a large number of component options, and it may be used in both primary and revision arthroplasties. The first results in 170 cemented knees (161 patients) with 2- to 5-year follow-up periods (average, 3.1 years) were very encouraging (excellent or good in 95% of knees, based on the British Orthopaedic Association knee assessment system). Poor results were seen only in revision cases. There have been no mechanical implant failures and no platform bearing dislocations, and the platforms continue to move as documented by postoperative roentgenograms, which show the metal markers of the platforms moving anteriorly in flexion and posteriorly in extension.

Late failure and revisions of old-type total knee replacements.

This paper reports the failure rate and survival of old-generation total knee replacements (TKR). Revision operations are also discussed. During a 5-year period from 1974 to 1979, 117 patients, 165 knees, were operated. The prostheses used were Geomedic in 75 knees and Attenborough in 90 knees. Revision was performed in 46 knees (28%). Six knees (4%) were infected. The survival time from implantation averaged 4.3 years, and the followup was 7 to 13 years for the Geomedic (mean 9.7) and 6 to 9 years for the Attenborough (mean 6.7). Mechanical problems were related to loosening of the tibial and femoral components, and revision was required for this reason. The success rate of the revision was 50% at 5.4 years; the less invasive the primary operation, the simpler the revision. Constrained prostheses must be used when ligaments are not intact. In case of infection, removal of the implants is not always necessary.

Patellectomy for osteoarthritis. A study of eighty-one patients followed from two to twenty-two years.

Eighty-one patients treated by patellectomy for osteoarthritis have been reviewed. Eighty-seven knees were examined with a mean follow-up period of six and a half years. Clinical and radiological assessment was carried out and the results have been analysed. A good result was achieved in 53 per cent, a fair result in 26 per cent and a poor result in 21 per cent. The overall result did not deteriorate significantly with time and the radiological appearance of the tibiofemoral joint deteriorated minimally. Pain before operation, radiological changes at the patellofemoral and tibiofemoral joints and the duration of immobilisation after operation were analysed against the end-result. The only factor before operation that indicated a good prognosis was a minimal radiological change at the tibiofemoral joint. Immobilisation for at least three weeks after operation appeared to be beneficial.