Document Type: RESEARCH PAPER
Shahid Beheshti University of Medical Sciences, Tehran, Iran
Bone Joint and Related Tissues Research Center, Akhtar Hospital, Shaheed Beheshti University of Medical Sciences, Tehran, Iran
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 this regard. In the current randomized clinical study, the outcomes of computer tomography (CT)-based
PS (patient specific)-guided TKA were compared to the results of conventional instrumentation (CVI) TKA. The guides
were designed on the basis of distal femoral and proximal tibial pin orientation of the conventional related guides.
Methods: The present study was carried out on 24 TKA candidates randomly assigned to two PSI (n=12) and CVI
(n=12) groups. The patients were postoperatively followed for 2 years. Then, the hip-knee-ankle angle (HKAA), femoral
component flexion, and orientation of components in the coronal plane were measured. In addition, the Western
Ontario and McMaster Universities Osteoarthritis (WOMAC) Index and Knee Society Score (KSS) questionnaire were
completed for all the patients.
Results: The rate of the outliers of the HKAA was higher in the CVI group (41.7% and 8.3%; P=0.077); nevertheless,
the difference was not significant in this regard. The rate of the outliers of other radiographic measurements and
operational time were similar in both groups. Furthermore, there was no significant difference between the two groups
in terms of the WOMAC and KSS.
Conclusion: The CT-based PS-guided TKA may result in the improved postoperative mechanical alignment of the limb
and should be considered in complicated TKAs. However, future studies should investigate whether the results of PSI
TKA support the considerably higher costs of this technique.
Level of evidence: II