The patient results and satisfaction of knee arthroplasty in a validated grading system

  • Christiaan Rudolf OosthuizenEmail author
  • Catherine Van Der Straeten
  • Innocent Maposa
  • Christian Hugo Snyckers
  • Duwayne Peter Vermaak
  • Sebastian Magobotha
Original Paper



The validated Knee Osteoarthritis Grading System (KOGS) was implemented and clinical results were compared with patient satisfaction data and implant survivorship in a multi-centre study with surgeons familiar with unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA).

This is also the first study to evaluate the prevalence of UKA and TKA in consecutive osteoarthritis (OA) knee arthroplasties assessed by this system..


A consecutive cohort of knees was gathered at three different institutions as categorized by KOGS and surgically treated with the recommended implant unless clinical reasons or patient preference precluded such an option.

One thousand one hundred seventy-seven consecutive knees were evaluated including 311 TKA (26%), 695 medial UKA (59%), 154 lateral UKA (13%) and 17 PFA (2%) and the results of the categories evaluated with the Oxford Knee Score (OKS) and the complications reflected in the different categories.


The failure rate of the UKA (3.5%) or TKA (1.6%) is not higher than accepted results in the literature and the difference in complications is negligible between the UKA (72%) and TKA (26%) cohorts.

Revision of a UKA to a TKA as an endpoint was 0.58% with ipsilateral progression at 0.8% over a period of five to 84 months (mean follow-up of 36 months) despite the ‘excessive’ proportion of UKA in this cohort.

The Oxford Score improvement is significant in TKA and UKA and contributes to the acceptable outcomes (The OKS for TKA improved from 20 pre-operatively to 36 post-operatively and the UKA improved from 22 pre-operatively to 39 post-operatively).


KOGS achieves acceptable early survival and functional results when implemented and is a suitable tool for identifying the preferred implant as was validated.


X-ray Osteoarthritis Grading Knee Arthroplasty Replacement 



The authors would like to thank Margaret Houman (Research Manager) and Andricha Viljoen (Researcher).

Author declarations

We, the authors declare that this manuscript is original, has not been published before and is not currently being considered for publication elsewhere.

We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. All authors have participated in the research. We further confirm that the order of authors listed in the manuscript has been approved by all of us.

We understand that the Corresponding Author, CR Oosthuizen, is the sole contact for the Editorial process.

Compliance with ethical standards

Conflict of interest

All authors declare that they received no research grants from funding agencies for this research.

Author 1 is an ad hoc paid consultant for Zimmer Biomet and Amplitude. Author 2 has received a speaker honorarium for a presentation on general aspects of Research and Innovation from Smith & Nephew.

No other interests required declaration as no benefits in any form have been received from a commercial party related directly or indirectly to the subject of this article.

Ethical approval

Ethical approval was obtained from the Human Research Ethics Committee at the University of the Witwatersrand (WITS) to study the data and X-rays of the individual orthopaedic practices with Clearance Certificate Nos. M1704111 and M1704112. All procedures performed in studies involving human participants were in accordance with the ethical standards of the above named institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Copyright and license term

The appendix containing the synopsis of KOGS and the KOGS flowchart with radiographs was published as an open access article under the Creative Commons Attribution License CC BY-NC-ND. [Oosthuizen CR, Takahashi T, Rogan M, et al. (2019) The Knee Osteoarthritis Grading System for Arthroplasty. J Arthroplasty 34:450–455.], which permits unrestricted use, distribution and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source.


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Copyright information

© SICOT aisbl 2019

Authors and Affiliations

  1. 1.Private Orthopaedic PracticeJohannesburgSouth Africa
  2. 2.Division of Orthopaedic SurgeryUniversity of the WitwatersrandJohannesburgSouth Africa
  3. 3.Head of the Health Innovation and Research InstituteGhent University HospitalGhentBelgium
  4. 4.Faculty of Health Sciences, Wits School of Public HealthUniversity of the WitwatersrandJohannesburgSouth Africa
  5. 5.Private Orthopaedic PracticePretoriaSouth Africa

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