Abstract
PurposeThis prospective randomized study compares the clinical and radiographic long-term results at least 16 years after total knee arthroplasty (TKA) between a mobile-bearing high flex and a fixed-bearing posterior-stabilized knee.MethodsIn 2000, we included 60 patients who underwent a TKA. Patients were divided into two groups. At the time of the follow-up after a minimum of 16 years (16.5 years ± 0.6), 16 patients had died for causes unrelated to the operation, 15 were lost to the follow-up. Five patients of the high flex group had a revision. The final evaluation included the hospital for special surgery score (HSS) and radiographs. Using the X-rays and the Knee Society Roentgenographic Evaluation and Scoring System, radiolucent lines and the maximal knee flexion were determined.ResultsNo significant differences between the two groups were found. The mean HSS score of LPS group patients was 87.9 (± 10.6) points and that of the high flex group was 93.1 (± 7.4) points. Five patients of the high flex group had undergone a reoperation. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the components.ConclusionThe long-term follow-up does not show any clear benefits and even a higher incidence of implant loosening using the mobile-bearing high-flex knee.
Highlights
The high flex total knee arthroplasty (TKA) was developed for patients requiring a deeper flexion up to 150° for reasons of profession, culture and religion
The long-term results after 10 years have shown no clear benefits and even higher incidence of implant loosening of the high flex knee system [2]
There were no relevant differences between the two groups
Summary
The high flex total knee arthroplasty (TKA) was developed for patients requiring a deeper flexion up to 150° for reasons of profession, culture and religion. The high flex knee (NexGen LPS Flex mobile, Zimmer Inc., Warsaw, USA) was specially designed to prevent increasing wear and to maintain knee stability in comparison to the regular posterior stabilised (PS) knee (NexGen LPS) Other studies had even shown a higher complication rate postoperatively using mobile-bearing systems. Ridgeway et al observed early coronal plane instability and knee pain in 25 cases within 2 years postoperatively [4]. Subluxation, dislocation, increasing wear rate and stress shielding were observed [4]. The long-term results after 10 years have shown no clear benefits and even higher incidence of implant loosening of the high flex knee system [2]
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