Total knee replacement (TKR) outcomes depend on accurate positioning of implants and restoration of the mechanical axis of the knee. Compared with standard techniques, patient-specific cutting guides are postulated to improve accuracy of bone resections, and therefore implant placement. Furthermore, patient-specific cutting guides are postulated to reduce operative time and increase efficiency by reducing the number of trays used.
This study evaluates these claims using the Visionaire (Smith & Nephew, Inc., Memphis, TN, USA) patient-specific system. The thickness of actual bone resections was compared with the predicted thickness (giving a resection 'error'). Data were also obtained on the number of trays used, skin-to-skin operating time and tourniquet time.
Forty-one TKRs were performed on 33 females (one bilateral) and seven males. Average resection errors were 0.22 mm medially and 0.05 mm laterally for the distal femur, 0.99 mm medially and 0.74 mm laterally for posterior femoral condyles, and 0.55 mm medially and 0.71 mm laterally for the proximal tibia. There were no significant differences in tourniquet time, skin-to-skin time or the number of trays used between the patient-specific and historical comparison groups.
Patient-specific cutting guides make accurate resections. Operative and tourniquet times and the number of trays used were no different to standard TKRs. Further investigation is needed to determine whether patient-specific cutting guides improve post-operative alignment and patient satisfaction.