Early outcome after total knee replacement using computed tomography-based patient-specific cutting blocks versus standard instrumentation

Purpose. To compare early outcome of total knee replacement (TKR) using computed tomography (CT)-based patient-specific cutting blocks versus standard instrumentation. Methods. 40 men and 44 women (90 knees) aged 45 to 88 (mean, 65) years who underwent TKR using standard instrumentation were compared with 39 men and 43 women (90 knees) aged 44 to 85 (mean, 64) years who underwent TKR using CT-based patient-specific cutting blocks. A single surgeon performed all TKRs through the medial parapatellar approach using a cemented prosthesis, with the posterior cruciate ligament retained and the patella resurfaced. Results. Respectively in the standard and patient-specific instrumentation groups, 74 and 70 patients were followed up for a mean of 30 and 14 months. The mean Oxford Knee Score was 19 and 19 preoperatively, 34 and 34 at 3 months, and 37 and 40 at 12 months (p = 0.02). 71% and 88% of patients achieved good-to-excellent outcome (Oxford Knee Score of >34) at 12 months (p = 0.008). The respective mean EQ-5D score was 54 and 52 preoperatively, 73 and 76 at 3 months, and 77 and 78 at 12 months. 18% and 2% of patients required a blood transfusion (p = 0.0002), with a mean blood loss of 292 and 254 g/l (p = 0.049). The mean tourniquet time was 45 minutes in both groups. There was no infection or revision in either group. Conclusion. Compared with standard instrumentation, the use of CT-based patient-specific cutting blocks for TKR achieved higher Oxford Knee Score at 12 months and lower blood loss and transfusion rate.