Comparative study of CT guided patient specific jig assisted TKA and conventional instrumentation TKA

Purpose: Comparing the technology of CT guided jigs assisted surgery with conventional instrumentation system in restoring the mechanical axis in total knee arthroplasty.

Method: Randomized two groups of 10 patients each were operated by Conventional instrumentation and CT guided pre-designed patient specific jigs. Intra and postoperative blood loss, operative time and correction of mechanical axis was recorded and compared.

Results: Mean rotational femoral angle was 1.0° for cases group and 1.5° for the control group, difference was statistically significant. The difference in preoperative and postoperative HKA angles between case and control groups was found to be significant in both groups but more in cases group. The alignment of knee in cases was closer to ideal 6-degree valgus alignment than the control group. The mean PCV fall in postoperative period in case group was 2.66 and in control group was 3.5. The mean operative time using CT guided jigs was 52.80 min and that in control group using conventional instrumentation was 62.40 min.

Conclusion: Restoration of alignment axis and placement of femoral component was found to be more accurate with CT guided jigs as compared to conventional instrumentation. Patients having extra articular deformity in femur which hampers the insertion of alignment rod properly to assess the anatomical axis are benefited by these patient specific jigs which obviate the need for intramedullary rod insertion. PSI is more precise as compared to conventional system but tibial jig placement requires improvement as it’s less conforming than femoral jigs which can lead to intraoperative errors.