Case Control Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Jul 18, 2016; 7(7): 426-433
Published online Jul 18, 2016. doi: 10.5312/wjo.v7.i7.426
Computerized tomography based “patient specific blocks” improve postoperative mechanical alignment in primary total knee arthroplasty
Raju Vaishya, Vipul Vijay, Vikas P Birla, Amit K Agarwal
Raju Vaishya, Vipul Vijay, Vikas P Birla, Amit K Agarwal, Department of Orthopaedics, Joint Replacement and Arthroscopy, Indraprastha Apollo Hospital, New Delhi 110076, India
Author contributions: Vaishya R helped in performing the surgery and designing the research; Vijay V helped in data collection and preparation of the manuscript; Birla VP helped in data collection and statistics; Agarwal AK helped in preparation of manuscript.
Institutional review board statement: The study was approved by the IRB of the institution.
Informed consent statement: All the patients included in the study gave an informed consent for inclusion in the study.
Conflict-of-interest statement: No conflicts of interest to declare.
Data sharing statement: The authors are willing to share the data of the present study.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Dr. Vipul Vijay, Department of Orthopaedics, Joint Replacement and Arthroscopy, Indraprastha Apollo Hospital, Sarita Vihar, New Delhi 110076, India.
Telephone: +91-11-29871210
Received: January 11, 2016
Peer-review started: January 14, 2016
First decision: February 29, 2016
Revised: March 14, 2016
Accepted: May 7, 2016
Article in press: May 9, 2016
Published online: July 18, 2016

AIM: To compare the postoperative mechanical alignment achieved after total knee arthroplasty (TKA) using computer tomography (CT) based patient specific blocks (PSB) to conventional instruments (CI).

METHODS: Total 80 knees were included in the study, with 40 knees in both the groups operated using PSB and CI. All the knees were performed by a single surgeon using the same cruciate sacrificing implants. In our study we used CT based PSB to compare with CI. Postoperative mechanical femoro-tibial angle (MFT angle) was measured on long leg x-rays using picture archiving and communication system (PACS). We compared mechanical alignment achieved using PSB and CI in TKA using statistical analysis.

RESULTS: The PSB group (group 1) included 17 females and seven males while in CI group (group 2) there were 15 females and eight males. The mean age of patients in group 1 was 60.5 years and in group 2 it was 60.2 years. The mean postoperative MFT angle measured on long-leg radiographs in group 1 was 178.23° (SD = 2.67°, range: 171.9° to 182.5°) while in group 2, the mean MFT angle was 175.73° (SD = 3.62°, range: 166.0° to 179.8°). There was significant improvement in postoperative mechanical alignment (P value = 0.001), in PSB group compared to CI. Number of outliers were also found to be less in group operated with PSB (7 Knee) compared to those operated with CI (17 Knee).

CONCLUSION: PSB improve mechanical alignment after total knee arthroplasty, compared to CI. This may lead to lower rates of revision in the PSB based TKA as compared to the conventional instrumentation.

Keywords: Knee, Replacement, Arthroplasty, Patient specific jigs, Conventional jigs

Core tip: Computer tomography (CT) based patient specific blocks (PSB) can help restore the mechanical axis of the patients undergoing primary total knee replacement. In the present study, the PSB group had significantly better post-operative mechanical axis as compared to the conventional instrumentation group. CT based PSB holds promise to help in accurate restoration of the mechanical axis and might decrease the rates of revision after total knee arthroplasty.