Summary

Titanium fixation devices used in high tibial osteotomy procedures do not influence the outcomes of quantitative MRI T2-mapping of knee cartilage

Abstract

Introduction

High tibial osteotomy (HTO) is an effective therapy to delay joint replacement in patients with early stage kneeosteoarthritis. Quantitative biochemical magnetic resonance imaging (MRI) techniques are increasingly used in osteoarthritis research to study therapeutic effects on cartilage composition and to accurately compare different treatment strategies. An important challenge for the application of these techniques in the context of HTO is the presence of metal fixation devices after the procedure, causing artifacts and an unknown influence on quantitative MRI outcomes. Our purpose was to assess the influence of titanium fixation devices on the outcomes of T2-mapping of knee articular cartilage, a widely used quantitative MRI technique to measure collagen content and network integrity in cartilage.

Methods

Five human cadaveric knee joints underwent T2-mapping with a 3D fast spin-echo sequence with 5 echo times (3, 13, 27, 40, 68 ms) before and after implantation of a fixation device. Scanning was performed on a 3 Tesla whole body MRI scanner using a 8-channel knee coil. A titanium locking plate widely used for HTO was fixated to the medial side of the proximal tibia using titanium screws by an experienced orthopaedic surgeon. The outcomes of T2-mapping, T2 relaxation times, were calculated in 6 cartilage regions (located in the medial and lateral weight-bearing and posterior cartilage of the femoral condyles and tibial plateaus). In each region, three corresponding central slices were carefully selected in the
scans with and without the implanted fixation device by an experienced researcher. T2 relaxation times before and after implantation of the metal fixation devices were compared with paired t-tests.

Results

Mean T2 relaxation times before and after implantation of the titanium fixation device for the different regions were as follows: femur posterior lateral 50.5 vs. 52.7 ms (p=0.23); femur posterior medial 57.8 vs. 59.5 ms (p=0.41); femur weight-bearing lateral 61.1 vs 58.7 ms (p=0.30); femur weight-bearing medial 58.4 vs. 56.3 ms (p=0.54); tibia weight-bearing lateral 62.6 vs. 58.9 ms (p=0.07); and tibia weight-bearing medial 58.0 vs. 54.0 ms (p=0.13). The paired t-tests showed no significant differences between the scans acquired with and without the metal implants.

Discussion And Conclusion

Based on the current data, we found no evidence to suggest that T2 relaxation times are influenced by the titanium fixation device. Thus, we propose that it is possible to implement T2-mapping as a quantitative MRI technique to evaluate the effect of the HTO on cartilage quality in clinical studies.