Background: Recently, patient-specific instrumentation (PSI) systems have been developed in order to increase the accuracy of component positioning during total knee arthroplasty (TKA). However, the findings of previous studies are controversial. In current randomized clinical study, the outcomes of CT-based PS guided TKA were compared with results of conventional instrumentation TKA (CVI). The guides were designed on the basis of distal femoral and proximal tibial pin orientation of the conventional related guides.
Methods: There were 24 TKA candidates, which assigned randomly to two equal groups of PSI and CVI. The patients were followed for 2 years, postoperatively. After 2 years, the hip knee ankle angle (HKAA), femoral component flexion and orientation of components in coronal plane were measured. Also, Western Ontario & McMaster Universities Osteoarthritis (WOMAC) Index and knee society score (KSS) were completed for all patients.
Results: Although nonsignificant, the rate of outliers of HKAA was significantly higher in CVI group (41.7% Vs 8.3%, P=0.077). The rate of outliers of other radiographic measurements and the operational time were the same. Furthermore, there was no significant difference in term of WOMAC and KSS.
Conclusion: CT-based PS guided TKA may result in improved postoperative mechanical alignment of the limb and should be considered in complicated TKAs. However, future studies should address whether the results of PSI-TKA support the considerably higher cost of this technique.
Keywords: Mechanical alignment, Patient-specific instrumentation, Total knee arthroplasty
Level of Evidence: II