ass="h4">Introduction
Prosthetic
and oper
ative modific
ations in tot
al knee
arthropl
asty (TKA) h
ave been proposed to m
aximise post-oper
ative knee flexion
as it is essenti
al in routine function
al
activities.
ass="h4">Methods
We performed a double blind randomised controlled trial to compare clinical outcomes of primary cruciate-retaining TKA for osteoarthritis with the femoral component implanted in either 4掳 flexion in the sagittal plane (F) or in a neutral position (C). The primary outcome of knee flexion and secondary outcomes knee extension, quadriceps strength, WOMAC, SF-12v2, timed stand test, stair climb test and satisfaction were assessed at 1 year. Knee flexion and extension were also assessed intra-operatively. Implant flexion was measured from true lateral radiographs.
ass="h4">Results
Thirty-nine participants (40 knees) were recruited, 20 knees per group. Three subjects from the control group and two from the flexed group were lost to 1 year follow-up but numbers were sufficient to satisfy the sample size calculation. Significant differences were found between the groups in knee flexion (F: 113.6 卤 8.8掳 pre-operative, 122.4 卤 6.0掳 intra-operative, 110.2 卤 7.5掳 1 year, C: 117.4 卤 11.7掳, 117.4 卤 7.6掳, 103.5 卤 10.7掳. p = 0.031) and mental component score of the SF12-v2 (F 53.3 卤 13.2, C 61.1 卤 7.3, p = 0.009) but there were no significant differences in other outcomes and patients were equally satisfied.
ass="h4">Conclusion
Flexing the femoral implant in this cruciate retaining TKA system provided a significant difference in knee flexion compared to a neutral position. The improvement appears to occur predominantly at surgery and was not associated with a clinical or functional benefit at 1 year. (ACTRN12606000325505). Level of evidence: Level 1; randomised controlled trial.
