THE EFFECT OF POSTERIOR TIBIAL SLOPE ON POST OPERATIVE FLEXION AND FUNCTIONAL OUTCOMES IN TOTAL KNEE ARTHROPLASTY. A DOUBLE BLINDED RANDOMISED CONTROLLED TRIAL

We present a prospective trial examining the effect of posterior tibial slope at total knee arthroplasty (TKA) on the range of movement and functional outcome. Current literature shows little difference clinically in TKA with increasing posterior tibial slope. Previous studies have been retrospective or involved small numbers and may represent poor ligament balancing or inaccurate alignment. In a prospective, double-blinded, randomised controlled trial, 250 patients undergoing primary Profix TKA, were randomised to receive either a 0 or 4 degree posterior tibial cut. Range of movement (ROM) was measured pre-operatively, at 3 months and 1 year by a single clinical physiotherapist. SF-12 and WOMAC scores were calculated at the same visit. Both patient and physiotherapist were blinded to the angle of tibial slope. Mean one year post operative ROM was greater by 2 degrees (p=0.470) in those with a 4 degree tibial slope. Post operatively both groups had significant improvement in functional outcome scores. A 0.2 (p= 0.892) and 0.51 (p= 0.707) greater improvement in SF12 physical score and mental scores respectively was found in the 0 degree group at one year. There was also a 1.09 (p=0.718) greater improvement in WOMAC score with a 0 degree slope. In conclusion increased posterior tibial slope gives a marginally better but non-significant post operative ROM and makes no significant difference to functional outcome.