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The Bone & Joint Journal
Vol. 98-B, Issue 7 | Pages 939 - 944
1 Jul 2016
Boonen B Schotanus MGM Kerens B van der Weegen W Hoekstra HJ Kort NP

Aims

We wished to compare the clinical outcome, as assessed by questionnaires and the rate of complications, in total knee arthroplasty (TKA) undertaken with patient-matched positioning guides (PMPGs) or conventional instruments.

Patients and Methods

A total of 180 patients (74 men, 106 women; mean age 67 years) were included in a multicentre, adequately powered, double-blind, randomised controlled trial. The mean follow-up was 44 months (24 to 57).


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 123 - 123
1 Jul 2014
Kerens B Boonen B Schotanus M Kort N
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Summary Statement

This is the first report of a new technique for unicompartmental to total knee arthroplasty revision surgery in which patient specific guides are formed based on preoperative CT imaging. This technique can help to make revision surgery less technically demanding.

Introduction

Unicompartmental to total knee arthroplasty revision surgery can be a technically demanding procedure. Joint line restoration, rotation and augmentations can cause difficulties. This study describes a new technique in which single way fitting guides serve to position knee system cutting blocks.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 334 - 334
1 Jul 2014
Kerens B Boonen B Schotanus M Lacroix H Emans P Kort N
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Summary Statement

This paper is the first to compare the results of unicompartmental to total knee arthroplasty revision surgery between cases with explained pain and cases with unexplained pain. Revision surgery for unexplained pain usually results in a less favourable outcome.

Introduction

Although it is suggested in literature that results of UKA to TKA revision surgery improve when the mechanism of failure is understood, a comparative study regarding this topic is lacking.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 121 - 121
1 Jul 2014
Boonen B Schotanus M Kerens B van der Wegen W Kort N
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Summary

Alignment results did not differ between PSG and conventional instrumentation. A small reduction in operation time and blood loss was found with the PSG system, but is unlikely of clinical significance. Length of hospital stay was identical for both groups.

Introduction

Several techniques for aligning a TKA exist nowadays. Patient-specific guiding (PSG) has relatively recently been introduced to try to resolve the shortcomings of existing techniques while optimising the operative procedure. Still few reports have been published on the clinical outcome and on the peroperative results of this new technique. This prospective, double-blind, randomised controlled trial was designed to address the following research questions: 1. Is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA. 2. Is there a significant difference in operation time, blood loss and length of hospital stay between the 2 techniques.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 18 - 18
1 Dec 2013
Boonen B Kerens B Schotanus M Vangeneugden D Kort N
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Background:

Patient-specific guiding (PSG) is a relatively new technique for aligning a total knee arthroplasty (TKA). Limited data exist on the precise accuracy of the technique. The purpose of this study is to investigate whether there was significant difference between the alignment of the individual femoral and tibial components (in all three anatomical planes) as calculated pre-operatively and the actually achieved alignment in vivo.

Methods:

Twenty-six patients were included. Software permitted matching of the pre-operative MRI-scan (and therefore calculated prosthesis position) to a pre-operative full-leg CT-scan. After surgery a post-operative full-leg CT-scan could be superimposed onto the pre-operative CT-scan to accurately determine deviations from planning (see figure 1 and 2). This 3D-technique has an accuracy of 0.7–1.0 degrees.


The Bone & Joint Journal
Vol. 95-B, Issue 9 | Pages 1204 - 1208
1 Sep 2013
Kerens B Boonen B Schotanus MGM Lacroix H Emans PJ Kort NP

Although it has been suggested that the outcome after revision of a unicondylar knee replacement (UKR) to total knee replacement (TKR) is better when the mechanism of failure is understood, a comparative study on this subject has not been undertaken.

A total of 30 patients (30 knees) who underwent revision of their unsatisfactory UKR to TKR were included in the study: 15 patients with unexplained pain comprised group A and 15 patients with a defined cause for pain formed group B. The Oxford knee score (OKS), visual analogue scale for pain (VAS) and patient satisfaction were assessed before revision and at one year after revision, and compared between the groups.

The mean OKS improved from 19 (10 to 30) to 25 (11 to 41) in group A and from 23 (11 to 45) to 38 (20 to 48) in group B. The mean VAS improved from 7.7 (5 to 10) to 5.4 (1 to 8) in group A and from 7.4 (2 to 9) to 1.7 (0 to 8) in group B. There was a statistically significant difference between the mean improvements in each group for both OKS (p = 0.022) and VAS (p = 0.002). Subgroup analysis in group A, performed in order to define a patient factor that predicts outcome of revision surgery in patients with unexplained pain, showed no pre-operative differences between both subgroups.

These results may be used to inform patients about what to expect from revision surgery, highlighting that revision of UKR to TKR for unexplained pain generally results in a less favourable outcome than revision for a known cause of pain.

Cite this article: Bone Joint J 2013;95-B:1204–8.