RESEARCH ARTICLE


Does Postoperative Mechanical Axis Alignment Have an Effect on Clinical Outcome of Primary Total Knee Arthroplasty? A Retrospective Cohort Study



Mikhail Salzmann1, Peter Fennema2, Roland Becker1, Hagen Hommel3, 4, *
1 Hochschulklinikum der MHB Theodor Fontane, Städtisches Klinikum Brandenburg GmbH, Center of Orthopedics and Traumatology, Hochstraße 29, 14770 Brandenburg an der Havel, Germany
2 AMR Advanced Medical Research GmbH, Hofenstrasse 89b, 8708 Männedorf, Switzerland
3 KH-MOL GmBH Sonnenburger Weg 3, 16269 Wriezen, Germany
4 Medizinische Hochschule Brandenburg (MHB), Theodor Fontane, Fehrbelliner Straße 38, 16816 Neuruppin, Germany


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© 2017 Salzmann et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the KH-MOL GmbH, Sonnenburger Weg 3, 16269 Wriezen, Germany, Tel: +49 3345640401, Fax: +49 3345640402, Email: H.Hommel@khmol.de


Abstract

Background:

There is an ongoing debate whether patients with constitutional varus should be restored to neutral mechanical alignment following total knee arthroplasty (TKA).

Objective:

The aim of this retrospective cohort study is to determine whether mild unintentional postoperative varus alignment (3°–6°) influences TKA outcome in patients with and without preoperative varus alignment due to medial osteoarthritis of the knee.

Methods:

We analyzed 172 consecutive TKA cases between April 2011 and May 2014. Patients were divided into four groups based on their preoperative and postoperative hip-knee-ankle angles (HKA): preoperative varus ≤ 3° with postoperative varus position ≤ 3° (Group 1, n = 47); preoperative varus >3° with postoperative varus ≤ 3° (Group 2, n = 104); preoperative varus ≤ 3° with postoperative varus malalignment > 3° (Group 3, n = 3); and preoperative varus > 3° with postoperative varus malalignment > 3° (Group 4, n = 18). Patients were followed up until 2 years postoperatively.

Results:

Knee Society Score and Western Ontario and McMaster University Osteoarthritis Index scores for all study groups increased following TKA, with no postoperative differences at any time point. Group 4 performed significantly better on the Forgotten Joint Score than Group 2 (p = 0.019). Group 4 performed significantly better on the High Flexion Knee Score than Group 2 (p = 0.004) and Group 1 (p = 0.019). All other between-group differences were not statistically significant.

Conclusion:

Residual postoperative varus alignment of the lower limb does not appear to adversely affect clinical outcome following TKA for varus-type osteoarthritis.

Keywords: Osteoarthritis, knee, Total knee arthroplasty, Constitutional varus, Clinical outcome, Surgical accuracy, Retrospective cohort study.