Elsevier

The Journal of Arthroplasty

Volume 21, Issue 7, October 2006, Pages 1032-1037
The Journal of Arthroplasty

Original Article
Influence of Polyethylene Constraint on Tibial Component Fixation in Total Knee Arthroplasty. Follow-Up Report After 5 Years

https://doi.org/10.1016/j.arth.2005.08.025Get rights and content

Abstract

The influence of articulating surface design of AMK total knee prosthesis (DePuy, Johnson & Johnson) on migration and radiographic outcome at 5 years was evaluated. The knees were randomly allocated to receive a flat or a concave insert with retention of the posterior cruciate ligament when preoperative deformity was less severe and either a concave or a posterior-stabilized insert with resection of the posterior cruciate ligament when deformity was more pronounced. In 64 knees, migration was measured with radiostereometry. The posterior-stabilized component displayed more varus-valgus tilting than the concave insert. Other statistically significant differences in migration were not seen. Radiolucent lines were frequently seen without differences between prosthesis groups.

Section snippets

Patients and Methods

Eighty-three patients (87 knees) with noninflammatory gonarthrosis were operated with the AMK (DePuy, Johnson & Johnson) total knee replacement. Patients with a 5° or less varus-valgus alignment were randomly selected to receive either a relatively flat or a concave tibial plateau. The posterior cruciate ligament (PCL) was retained. Patients who had more than 5° varus-valgus alignment and /or extension defect of 10° or more were randomly selected to receive either a concave or a

Lost to Follow-Up and Revisions

Fifteen patients were lost to the 5-year follow-up. Two patients were revised before the 1-year follow-up [4]. After 2-year follow-up, one patient with a flat insert was operated with intramedullary nail because of supracondylar femoral fracture and had 25° of valgus alignment after nailing. Seven patients had died because of reasons unrelated to the TKA, one had dementia, three patients refused follow-up because of other disabilities, and one had moved abroad.

Radiostereometry

Eight to 9 spherical tantalum markers (size 0.8 mm) were inserted into the proximal tibia after preparation of the bone and before cementing of the components. Three 0.5-mm and three 0.8-mm tantalum markers were inserted in the polyethylene component. The biplanar radiostereometric technique and the UmRSA 3.2 software (RSA Biomedical Innovations, Umeå, Sweden) were used. Fictive points were used to measure translations [8]. Rotation around the transverse, longitudinal and sagittal axes, maximum

Radiographic Evaluation

Radiolucent lines around the tibial and femoral components were evaluated according to the Knee Society scoring postoperatively and after 2 and 5 years [12]. An orthopedic surgeon, who had not operated on any of the patients, evaluated the radiographs. The width of all zones around the tibial and femoral components is summarized resulting in a total score for each component. Radiolucent with a total score of 5 to 9 should be followed for progression and 10 or more signifies possible or

Clinical Evaluation

The Hospital for Special Surgery Knee Scores (HSS) [13] was used at the clinical evaluation.

Statistics

Mann-Whitney U test was used to evaluate the results at 5 years. P values less than .05 were regarded to represent statistically significant differences. Based on the number of knees available at 5 years, we could detect differences of rotation between 0.2° and 0.4° with at least 80% probability depending on the direction of the rotation and subgroup analyzed. With the same power, differences of 0.3 mm in lift-off and maximum subsidence could be detected. Correspondingly, differences of 0.6 mm

Small Deformity—Retained PCL

From 2 to 5 years, the absolute rotation about the longitudinal (internal/external rotation) and transverse (anterior/posterior tilting) axes tended to increase in the group with flat inserts, whereas minimum changes were seen in the concave group. There was also a tendency to increased rotation around sagittal axis (varus-valgus tilting) after 2 years in the group with concave inserts, but none of these tendencies resulted in any significant differences at 5 years. Neither did the translation

Discussion

In the 5-year follow-up, we found no definite influence of tibial implant design on clinical performance, regardless of the degree of preoperative deformity. The fixation of the tibial component was not influenced by choice of insert design in cases with minor deformity. In the group with more pronounced deformity, PS inserts displayed increased rotation about the sagittal axis. Most of the migration parameters studied showed a similar pattern suggesting that the joint area design had a very

Acknowledgment

This project was financially sponsored by the Swedish Medical Research Council (MRF K97-17X-07941-11B9), the Ingabritt and Arne Lundbergs Research Foundation, the Félix Neubergh Research Foundation, the Göteborg Medical Society, and DePuy, Johnson & Johns on.

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Benefits or funds were received in partial or total support of the research material described in this article from the Swedish Medical Research Council (MRF K97-17X-07941-11B9), the Ingabritt and Arne Lundbergs Research Foundation, the Félix Neubergh Research Foundation, the Göteborg Medical Society and DePuy, Johnson & Johnson.

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