MRI of the knee joint in the control group and after ACLR.

<p>In the sagittal cross section of a control knee (A), the medial meniscus is homogenously black. The femur and tibia are on top of one another. In the knee joint after ACLR, the lack of the ACL caused the tibia to be moved forwards (B1). However, the menisci are still homogeneously black (B2). There is no evidence of degeneration in AH, PI and PH of the medial menisci (C). There is also no evidence of degeneration in the lateral menisci (D).</p

Primer sequence, annealing temperatures (AT) and PCR product size for the different genes.

<p>Primer sequence, annealing temperatures (AT) and PCR product size for the different genes.</p

Results of the qRT-PCR. The normalized expression of medial menisci in the control and ACLR group is compared and the changes in expression are described.

<p>Results of the qRT-PCR. The normalized expression of medial menisci in the control and ACLR group is compared and the changes in expression are described.</p

Histological evaluation of the degeneration in the PI of menisci in the control (A, B) and ACLR (C, D) group.

<p>A four step scoring was performed using hematoxylin-eosin staining. In case of homogeneously stained matrix with balanced cell distribution (A) degeneration was graded O. If additional matrix clefts occurred, degeneration was graded 1 (B). Degenerative changes such as moderate basophilic (blue) matrix staining in accordance with matrix clefts have been graded 2 (C). Additional mucoid changes (circle in D) and the separation of the fibrocartilage represent third grade degeneration (D). The grade of degeneration in AH, PH and PI of all medial menisci has been determined (E). Clear degeneration was only able to be observed in the medial menisci after ACLR (F).</p

HE-staining-based four-stage scoring system for meniscal degeneration [32].

<p>HE-staining-based four-stage scoring system for meniscal degeneration [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159331#pone.0159331.ref032" target="_blank">32</a>].</p

Qualitative immunohistochemical analysis of type I collagen in the PI.

<p>No staining without antibody (A), weak staining in the control group and more intense staining after ACLR (C).</p

MRI-based classification of meniscal degeneration (adapted from [30]).

<p>MRI-based classification of meniscal degeneration (adapted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159331#pone.0159331.ref030" target="_blank">30</a>]).</p

Scatter graphs showing the distributions of the TRYCAT metabolism ratios.

<p>Scatter graphs showing the distributions of the TRYCAT metabolism ratios.</p

Scatter graphs showing the distribution of the serum levels of the measured TRYCATs in ng/mL.

<p>Scatter graphs showing the distribution of the serum levels of the measured TRYCATs in ng/mL.</p

Serum levels of TRYCATs in ng/mL.

<p>Results from MANCOVA controlled for age, sex, body mass index, presence of a cardiovascular disease and smoking; *p<0.05; KYN = kynurenine, KYNA = kynurenic acid, 3-HK = 3-hydroxykynurenine, AA = anthranilic acid.</p