Gene expression in human meniscal tears has limited association with early degenerative changes in knee articular cartilage

Abstract

Purpose/Aim: Meniscus tears are a common injury to the knee associated with the development of osteoarthritis. Gene expression in the injured meniscus may be associated with early degeneration in the articular cartilage. The purpose of this study was to test the hypothesis that gene expression in meniscus tears is associated with early degenerative changes in the articular cartilage at the time of partial meniscectomy.

Materials and methods: Torn meniscus was removed at the time of partial meniscectomy in 68 patients without radiographic osteoarthritis. Meniscal mRNA expression was measured by quantitative PCR for multiple molecular markers of osteoarthritis and cartilage homeostasis. The presence of early degenerative changes in the knee was recorded by X-ray (N = 63), magnetic resonance imaging (MRI, N = 48), and arthroscopy (N = 63). Gene expression was tested for correlation with the presence/absence of degenerative changes after adjusting for age, sex, and body mass index.

Results: Overall gene expression varied significantly with degenerative changes based on X-ray (P = 0.047) and MRI (P = 0.018). The linear combination of gene variation was also significant. However, only adiponectin (ADIPOQ) (P = 0.015) was expressed at a significantly lower level in patients with chondrosis on MRI, while the expression of ADIPOQ (P = 0.035) and resistin (RETN) (P = 0.017) was higher in patients with early degenerative changes on X-ray. None of the genes varied significantly with presence/absence of chondrosis as measured by arthroscopy.

Conclusions: There is an overall association of gene expression in meniscal tears to early degenerative changes in the knee, but only a limited number of specific genes demonstrate this relationship. The roles of adiponectin and resistin in knee injury and osteoarthritis deserve further study.

Keywords: Chondrosis; gene expression; meniscus tear; osteoarthritis; partial meniscectomy.

Fig. 1

Examples of presence/absence of degenerative changes based on X-rays, MRI and arthroscopy. X-rays: (A) no OA; (B) joint space narrow and osteophyte formation (arrow) as evidence for early OA. MRI: (C) chondrosis; (D) chondral flap. Arthroscopy: (E) no chondrosis; (F) chondrosis. FC = femoral condyle, TP = tibia plateau, MM = medial meniscus, LM = lateral meniscus