Contribution of patient-specific cutting guides to lower limb alignment for total knee arthroplasty.

UNLABELLED: Patient-specific cutting guides (PSCG) are an extension of preoperative planning for total knee arthroplasty (TKA). We wanted to evaluate their contribution to postoperative lower limb alignment. This study involved primary TKA cases being performed with PSCG between 10/05/2010 and 05/03/2013 and then followed prospectively. The analysis involved the PSCG usage and postoperative measurement of the patient's HKA, medial distal femoral joint angle (MDFA) and medial proximal tibia joint angle (MPTA). Of the 104 eligible cases, 68 were included; 11 of these cases were not performed completely with the PSCG as initially planned. Thus we compared these 11 cases with the 57 where PSCG were used. The preoperative HKA in the included cases was 175.8° ± 7.8; the postoperative angles on average were 179.2° ± 2.9 for the HKA, 89.9° ± 1.6 for the MDFA and 89.0° ± 2.3 for the MPTA. The average postoperative deviation from the target values was 2.22° ± 2.14 for the HKA angle, 1.07° ± 1.15 for the MDFA and 1.66° ± 1.90 for the MPTA. There were no significant differences between the two groups in any of the measurements. The lower limb alignment goal was achieved in 50 cases (73%), with 41 of these achieved with PSCG (82%). Of the 18 cases where the target was not achieved, PSCG were used 16 times (88%). In this study cohort, lower limb alignment was not significantly closer to an HKA of 180° or achieved more often with the use of PSCG versus standard instrumentation. Since the results of the two groups can be superimposed, we found no evidence that use of PSCG improves postoperative lower limb alignment. LEVEL OF EVIDENCE IV. STUDY TYPE: Cohort.