Abstract
Introduction
High flexion knee arthroplasties have been designed to allow up to 155 degrees flexion and enable high flexion activities such as kneeling and squatting. To date randomised controlled trials have shown no difference in range of movement (ROM) between high flexion and standard designs.
Objectives
The aim of this study was to determine if there is a difference in functional outcome and ROM between the standard and high flexion design of the PFC Sigma TKA system.
Methods
84 patients with the diagnosis of osteoarthritis undergoing primary total knee arthroplasty were randomised to receive either a PFC Sigma or PFC Sigma RP-F total knee arthroplasty. ROM, Oxford Knee Score, Knee Society Score, Patella score and SF-12v2 were assessed independently before and at one year after surgery. Patients were blinded to the implant they received.
Results
42 patients in each group were included in this study and underwent surgery. 77 patients (92%) completed their one-year follow-up. There was no statistically significant difference in preoperative scores between groups.
At one year there was a statistically significant difference in ROM between the groups with a mean of 105 degrees in the PFC Sigma and 114 degrees in the PFC Sigma RP-F group (p=0.01). There was also a statistically significant difference in flexion with 106 degrees and 115 degrees respectively (p=0.007). The difference in improvement in ROM and flexion was also statistically significant between the groups (p=0.009 and p=0.008).
There was no statistically significant difference in any of the functional outcome scores.
Conclusions
This is the first randomised controlled trial to show a statistically significant difference in ROM and flexion between a standard and a high flexion design TKA. Further follow-up will be carried out to determine if these differences persist over time and to evaluate the long-term survival of the different designs.
