The correct combination
Case 144
【Progress】
They consulted with orthopedists in our hospital. They were given nonsteroidal anti-inflammatory drugs and/or direct injection of steroid + xylocaine to the painful lesions.
【Discussion】
In the knee joint, the medial site is more supportive to the body weight than the lateral site. Medial condyle and medial meniscus are larger than lateral condyle and lateral meniscus, respectively. The attachments of anterior cruciate ligament (ACL) and posterior cruciate ligament are central-anterior-medial portion and central-posterior medial portion, respectively of tibia. ACL attaches to the medial meniscus which is believed to be caused the simultaneous injury of ACL and medial longitudinal (vertical) meniscus tear (1).
Spontaneous osteonecrosis of the knee (SONK) usually occurs at the medial condyle of the femur. It initially occurs from bone marrow edema, the less volume of cartilage of the femur medial condyle and/or after the less volume of the medial meniscus (1-4). Bone edema advances necrosis of the bone. As time progress, when treatment is appropriate, the bone marrow area becomes decreased and the necrotic area becomes cystic degeneration (1, 2). SONK affects middle age and elderly women with osteoporosis. It represents subchondral microfracture and often associates with meniscal root tear. In our patient with SONK suffering from throbbing pain and stabbing pain (Fig. 3), she is a 72 year-old female probably with osteoporosis whose knee has the horizontal tear of meniscus, simultaneously.
The image of subchondral bone plate fracture varies depending on the stage, subchondral bone plate injury is possible to develop to SONK (1, 2). It initially causes bone edema, followed by fluid-filled cleft within the subchondral bone plate, followed by granulation tissue and callus, representing the thickness of subchondral bone plate (5). In our case, subchondral cleft was shown on T2WI and subchondral fluid collection on fat suppression T2WI (Fig. 4).
An intraarticular loose body is the same term word as intraarticular body or fragment which is not always movable. Pathological examination reveals the intraarticular fragment composes of bone and cartilage (6). It possibly turns the cartilage component into bone component because it gets nutrients from intraarticular fluid. It can lead to damage the articular cartilage, causing osteoarthritis. It is important to comment the exact site of the intraarticular fragment on MRI for retrieval of the fragment via arthroscopic approach. Further, it is imperative to differentiate intraarticular fragment from meniscal ossicle which is shown calcified nodule within the meniscus, especially most often found within the posterior horn of the medial meniscus on MRI (7). In our case, calcified nodule was shown intraarticular space but not within the meniscus, diagnosing intraarticular loose body (Fig. 2).
【Summary】
We presented five cases suffering from knee joint pain: Meniscus radial tear, Intraarticular loose bodies, Spontaneous osteonecrosis of the knee (SONKS), Sub-chondral bone plate microfracture, Injury of the medial collateral ligament. It is borne in mind that anterior crucial ligament attaches to medial meniscus, which is believed to be caused the simultaneous injury of ACL and the longitudinal (vertical) medial meniscus tear. Spontaneous osteonecrosis of the knee (SONK) usually occurs at the medial condyle of the femur. SONK affects middle age and elderly women with osteoporosis. It represents subchondral microfracture and often associates with meniscal root tear. Subchondral bone plate fracture initially causes bone edema, followed by fluid-filled cleft within the subchondral bone plate, followed by granulation tissue and callus, representing the thickness of subchondral bone plate. Intraarticular fragment composes of bone and cartilage. It possibly turns the cartilage component into bone component because it gets nutrients from intraarticular fluid. It can lead to damage the articular cartilage, causing osteoarthritis. Meniscal ossicle which is shown calcified nodule within the meniscus, especially most often found within the posterior horn of the medial meniscus.
【References】
1.Geijer, M, et al. MR appearance of the temporal evolution and resolution of spontaneous osteonecrosis of the knee: a case report. Acta Radiol Open. 2017 Feb; 6(2): 2058460116688719
2.Jordan RW, et al. The importance of early diagnosis in spontaneous osteonecrosis of the knee - A case series with six year follow-up. Knee 2016; 23: 702–707.
3.Juréus J, et al. The natural course of spontaneous osteonecrosis of the knee (SPONK). A 1- to 27-year follow-up of 40 patients. Acta Orthop 2013; 84: 410–414.
4.Zywiel MG, et al. Osteonecrosis of the knee: a review of three disorders. Orthop Clin North Am 2009; 40: 193–211.
5.Viana SL, et al. MRI of subchondral fractures: a review. Skeletal Radiol 2014; 43: 1515–1527.
6.Milgram, JW et al. Multiple Loose Bodies: Formation, Revascularization, and Resorption A 29-Year Followup Study.[Article] Source Clinical Orthopaedics & Related Research. 1996; 322:152-157.
7.Mohankumar R, et al. Meniscal Ossicle: Posttraumatic Origin and Association With Posterior Meniscal Root Tears. American Journal of Roentgenology. 2014;203: 1040-1046.
2019.5.15