Search

Abstract Background With the advent of MRI (Magnetic Resonance Imaging), Synovial lesions around knee are being more and more easily detected. Synovial lesions of knee present with boggy swelling, effusion, pain, and restriction of motion. Differential diagnoses of such lesions include pigmented villonodular synovitis, synovial lipoma, synovial chondromatosis, rheumatoid arthritis, synovial hemangioma, amyloid arthropathy, xanthomata and lipoma arborescens. CT and MRI often help in diagnosis of such lesions. MRI of Lipoma Arborescens has been regarded to have characteristic diagnostic appearance – it includes a synovial mass with frond‐like architecture and fat signal intensity on all pulse sequences. Sometimes Lipoma Arborescens can present in conjunction with inflammatory arthritis. Synovectomy is often curative for such conditions. Findings We report two cases where lesions diagnosed as Lipoma Arborescens on MRI subsequently revealed to be chronic inflammatory synovitis, characterized by absence of fat infiltration in histopathological examination – refuting the original diagnosis. There was infiltration of lymphocytes and neutrophils in the synovium, suggestive of chronic inflammatory arthritis. Both of these patients required management from rheumatologist, and had relief of symptoms after use of methotrexate and hydroxychloroquine. We also report a third case, where a loose body appearing as chondral fragment on arthroscopy was subsequently diagnosed as an organized hematoma on histopathological examination. Conclusion Diagnostic pitfalls after MRI of the knee is not uncommon. For example ‐ normal variant of meniscomeniscal ligaments have been reported as meniscal tears; motion artifacts have been falsely reported as meniscal injuries; and meniscofemoral ligament can appear as free osteochondral fragment. In most of these cases, a routine arthroscopy is enough to clear the confusion. However, as evident in the three cases described here ‐ in some synovial lesions of knee joint, even after MRI and arthroscopic examination, histopathological confirmation may still be prudent. In spite of availability of advanced imaging technologies and high definition arthroscopy equipment, an arthroscopy surgeon still must not forget the value of histopathological examination in establishing the true nature of synovial lesions of the knee joint.

Animal osteoarthritis (OA) models have been developed to understand OA progression and evaluate new OA therapies. However, individual variations in joint lesions remain a critical problem in most current OA models. We established a novel rabbit model by creating a longitudinal tear in the medial meniscus body that was reproducible and similar to posttraumatic biomechanical disturbances in human OA. New Zealand rabbits underwent surgery and were assessed for 9 weeks. The rabbits were randomized into the sham control, medial meniscal tear (MMT), and anterior cruciate ligament transection (ACLT) groups. The animals were sacrificed at 4, 6, and 9 weeks posttreatment. The knee joints were harvested for histological and gene expression assessments. Both the MMT and ACLT procedures led to time-dependent degenerative changes in the femoral condyle cartilage. At each time point, the MMT group cartilage showed more severe degenerative changes than did the ACLT group cartilage. Consistently, inflammatory cytokine and catabolic gene expression were significantly higher, and anabolic gene expression was significantly lower in the MMT group than in the ACLT group. MMT treatment caused more severe structural damage to the cartilage and higher catabolic gene expression levels than the ACLT model at each time point. The MMT model may be highly beneficial in investigating posttraumatic OA (PTOA) development, especially PTOA from a meniscal injury. The MMT model replicated key features of human PTOA, including meniscal lesions, inflammatory responses, and the progression to osteoarthritic cartilage degeneration, thereby providing an exciting new avenue for translating promising treatments to clinical practice., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Anterior cruciate ligament (ACL) tears occur in isolation or in tandem with other intra-articular injuries such as meniscus tears. The impact of injury pattern on the molecular biology of the injured ACL is unknown. Here, we tested the hypothesis that the biological response of the ACL to injury varies based on the presence or absence of concomitant meniscus tear. We performed RNA-seq on 28 ACL tears remnants (12 isolated, 16 combined). In total, 16,654 transcripts were differentially expressed between isolated and combined injury groups at false discovery rate of 0.05. Due to the large number of differentially expressed transcripts, we undertook an Ensembl approach to discover features that acted as hub genes that did not necessarily have large fold changes or high statistical significance, but instead had high biological significance. Our data revealed a negatively correlated module containing 5,960 transcripts (down-regulated in combined injury) and a positively correlated module containing 2,260 transcripts (up-regulated in combined injury). TNS1, MEF2D, NOTCH3, SOGA1, and MLXIP were highly-connected hub genes in the negatively correlated module and SCN2A, CSMD3, LRC44, USH2A, and LRP1B were critical hub genes in the positively correlated module. Transcripts in the negatively correlated module were associated with biological adhesion, actin-filament organization, cell junction assembly, and cell matrix adhesion. The positively correlated module transcripts were enriched for neuron migration and exocytosis regulation. These findings indicate genes and pathways reflective of healing deficiency and gain of neurogenic signaling in combined ACL and meniscus tears, suggesting their diminished repair potential. The biological response of ACL to injury could have implications for healing potential of the ligament and the long term health of the knee. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2612-2621, 2018., (© 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Concentrations of pro- and anti-inflammatory cytokines in synovial fluid samples collected from patients with chronic meniscal tears were investigated. An acute inflammatory response is generally reported 24-48 h after knee injury, but the largest body of data available in literature concerns anterior cruciate ligament injury and very little information is available about the balance of soluble factors in the synovial fluid of knees with chronic meniscal tears. Sixty-nine patients (46 males and 23 females) with meniscal tear that occurred more than 3 months earlier were enrolled. According to cartilage integrity assessment by arthroscopic examination, patients were assigned to one of the following groups: (i) no chondral damage (n = 18); (ii) chondral damage graded from I to II (n = 15); and (iii) chondral damage graded from III to IV (n = 37). In all groups, levels of IL-10 and inflammatory cytokines IL-6, TNF-α, and IL-8 where greater compared with those reported in the intact population; by contrast, levels of IL-1ra and IL-1β were significantly lower. Interestingly, IL-6 levels were higher in female than male patients. Cytokine levels did not correlate with degree of chondral damage. IL-6 and IL-1ra levels positively correlated with IL-1β, and negatively correlated with TNF-α. Interestingly, levels of IL-1β and TNF-α were inversely correlated. Our data demonstrate increased levels of pro-inflammatory cytokines (IL-6, IL-8, and TNF-α) in the chronic phase of meniscal trauma. This pro-inflammatory state is maintained in the joint from the time of initial injury to several months later and could be a key factor in hampering cartilage regeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:340-346, 2017., (© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)