[ASSOCIATION OF ANTERIOR CRUCIATE LIGAMENT DEGENERATION WITH MEDIAL MENISCUS TEAR AND INTERCONDYLAR NOTCH IMPINGEMENT]

OBJECTIVE

To explore the association of anterior cruciate ligament (ACL) degeneration with intercondylar notch impingement and the medial meniscus tear in knee osteoarthritis (KOA).

METHODS

Between July 2014 and February 2016, 55 KOA patients (55 knees) with ACL degeneration (degeneration group) and 55 KOA patients (55 knees) without ACL degeneration (control group) were included in the study. No significant difference was found in gender, age, body mass index, and side between 2 groups (P>0.05). The notch width index was measured on preoperative MRI to evaluate whether the intercondylar notch was narrow. The location of the medial and lateral meniscus tear and osteophyte of the ACL tibial insertion were observed under arthroscopy, and the incidences of the meniscus tear and osteophyte were calculated.

RESULTS

There was no significant difference in anterior horn and body tear of the medial meniscus and in anterior horn, body, posterior horn, and root tear of the lateral meniscus (P>0.05). Significant difference was found in the posterior horn and root tear of the medial meniscus, osteophyte of the ACL tibial insertion, narrow intercondylar notch, and the notch width index between 2 groups (P<0.05). The incidence of root tear of the medial meniscus was 53.8% (7/13) in 13 knees with osteophyte of the ACL tibial insertion and was 16.5% (16/97) in 97 knees without osteophyte, showing significant difference (χ²=9.671, P=0.002).

CONCLUSIONS

There is a strong association of ACL degeneration with posterior horn and root tear of the medial meniscus and intercondylar notch impingement in KOA. And the high incidence of root tear of the medial meniscus in knee is correlated with osteophyte of the ACL tibial insertion.

Bone morphogenetic protein 2/SMAD signalling in human ligamentocytes of degenerated and aged anterior cruciate ligaments

OBJECTIVE

Anterior cruciate ligament (ACL) degeneration leads to knee instability and favors osteoarthritis (OA) progression. During ageing the growth factor sensitivity of ligaments changes but nothing is known about BMP2-signalling and -sensitivity in degenerated ACLs. This study addressed the question whether a dysregulated BMP2 signalling might contribute to age- and OA-dependent ACL degeneration.

METHOD

ACL samples from patients with/without OA of different ages (<60 and ≥60 years, males, females) were graded histopathologically (n = 45). After stimulation of cultured ACL fibroblasts with 5 nM BMP2 for different time points, phosphorylation of SMAD1/5/8 and gene expression of crucial BMP2 signalling proteins, ligamentogenic and chondrogenic transcription factors, scleraxis (SCX) and SOX9, were analyzed.

RESULTS

ACL samples displayed different grades of degeneration, often associated with synovitis and calcium deposits. Degeneration correlated significantly with synovitis. ACL fibroblasts expressed BMP type I receptors ALK3 and ALK6 and the BMP type II receptor BMPRII. Donors could be divided into "responders" and "non responders" since their BMP2 mediated SMAD1/5/8 phosphorylation level differed. Basal ID1 expression was lower in cells derived from OA compared with non-OA patients and BMP2 led to an ID1 induction in both. Irrespective of BMP2 stimulation, the donor age significantly influenced the expression profile of BMP6 and SCX but not BMP signalling. The BMP2-mediated SMAD6 expression differed between OA and healthy ACL fibroblasts.

CONCLUSION

Our data indicate that the expression level of BMP2/SMAD target genes such as ID1 and SMAD6 was reduced in ACL fibroblasts derived from OA compared with non OA patients.