Midterm results of mobile-bearing total knee arthroplasty in patients younger than 65 years.

This study evaluated 117 patients younger than 65 years (average, 56 years) in whom mobile-bearing total knee arthroplasties were inserted. All patellae were resurfaced with a mobile-bearing patella implant. Followup averaged 102 months (range, 60-171 months). The average knee score was 91 points, with a pain score of 27 points (possible 30 points). There were eight (7%) revision surgeries in this series, with four malpositioned implants, one infection, and one case of osteolysis. Two patients had bearing revisions for bearing dislocation and polyethylene wear. Survivorship at 14 years was 88%.

Total knee arthroplasty with a mobile-bearing prosthesis: comparison of retention and sacrifice of the posterior cruciate ligament in cementless implants.

We compared patient outcome after total knee arthroplasties with two types of low-contact-stress (LCS) cementless implants: a meniscal-bearing implant that retained the posterior cruciate ligament (n = 147), and a rotating-platform implant requiring sacrifice of this ligament (n = 44). The minimum follow-up was 5 years (mean, 68.5 months). Pain was occasional or nonexistent at follow-up in 94.6% of patients with meniscal-bearing implants and 93.2% of patients with rotating-platform implants. The mean total range of motion was 120 degrees for patients with meniscal-bearing implants and 108 degrees for those with rotating-platform implants (P < 0.001). Mean total scores on the New Jersey Orthopaedic Hospital Knee Scale were 93.2 for meniscal bearings and 87.6 for rotating platforms (P < .001). Patellar complications, including two fractures, were seen in 1.0% of cases. Five meniscal-bearing and no rotating-platform implants have been revised. The 7-year overall survival rate was 97.5% for meniscal bearings and 100% for rotating platforms.

Survivorship analysis of cementless meniscal bearing total knee arthroplasty.

Four hundred seventy-three consecutive cementless cruciate retaining meniscal bearing primary total knee replacements were done on 375 patients from May 1985 to February 1991. These were observed for a 10-year period (average, 5 years). Seventeen (3.6%) required change of components because of mechanical failure. There were 12 polyethylene fractures or dislocations. There were 5 tibial subluxations secondary to ligamentous instability occurring at an average of 21 months postoperatively. There were 2 component loosenings secondary to bone graft resorption (1 femoral, 1 tibial). There were 5 infections (4 Staphylococcus aureus, 1 Pseudomonas). Significantly, with the exception of the 2 knees with bone graft resorption, there was no component (femoral, tibial, or patellar) loosening. Kaplan-Meier survival estimates, using as an endpoint of revision surgery for any mechanical reason (polyethylene breakage, polyethylene dislocation, or ligamentous instability), showed a survivorship of 94.6% at the 8-year interval. Survivorship related to mechanical loosening of fixation of any component at the 8-year interval was 99%.

Comparison of range of motion after posterior cruciate ligament retention or sacrifice with a mobile bearing total knee arthroplasty.

This study evaluated factors affecting range of motion at 24 months in 782 total knee arthroplasties (TKAs) performed between 1983 and 1987 in a nonrandomized, multicenter clinical trial by 17 independent surgeons. A mobile bearing prosthesis was used with either a posterior cruciate ligament (PCL)-retaining or PCL-sacrificing technique. Age and gender did not reveal any differences in outcome. For individual surgeons, the outcome was highly variable and did not reflect the number of cases performed. Postoperative range of motion was greater for the PCL-retaining implant; however, there was also a significant difference in the preoperative motion compared with the PCL-sacrificing device. Postoperative motion improved from preoperative for the whole group. Preoperative motion groups of < 90 degrees gained 28 degrees, 90 degrees to 105 degrees gained 15 degrees, and > 105 degrees lost 1 degree. The change in motion for patients without prior surgery was greater than for those with prior surgery.