Unilateral Meniscomeniscal Ligament
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n Case Report Unilateral Meniscomeniscal Ligament CHARLES M. CHAN, MD; JOHN P. GOLDBLATT, MD abstract Full article available online at Healio.com/Orthopedics. Search: 20121120-31 Four normal variants of meniscomeniscal ligaments have been previously reported in the anatomy, arthroscopy, and radiology literature. The anterior and posterior trans- verse meniscal ligaments are the 2 most commonly observed, with a reported fre- quency of 58% and 1% to 4%, respectively. The last 2 variants include the medial and lateral oblique meniscomeniscal ligaments and account for a combined frequency of 1% to 4%. This article describes 2 patients with unilateral meniscomeniscal ligaments observed Figure: Intraoperative arthroscopic image showing on magnetic resonance imaging. One patient had a unilateral lateral meniscomeniscal the course of the medial meniscomeniscal liga- ligament extending from the anterior horn of the lateral meniscus to the posterior horn ment (asterisk) from the anterior horn (AH) to the of the lateral meniscus and underwent conservative management. The second patient posterior horn of the medial meniscus adjacent to had a unilateral medial meniscomeniscal ligament with a concomitant medial menis- the medial tibial spine. Abbreviations: MFC, medial femoral condyle; MTP; medial tibial plateau. cus tear and underwent arthroscopic intervention. The ligament was stable intraopera- tively and, therefore, was not resected. Both patients had resolution of their symptoms. These 2 variants are additions to the previously described 4 normal intermeniscal ligament variants. The functions of the 2 new variants described in this article are poorly understood but are thought to involve meniscal stability. Accurate descriptions of normal variants can lead to the proper management of anomalous rare structures and prevent false imaging interpretations because these structures can closely mimic a double posterior cruciate ligament sign. Furthermore, an understanding of the various normal variants of intermeniscal ligaments can prevent unnecessary surgery that could result in further iatrogenic meniscus injury. Drs Chan and Goldblatt are from the Department of Orthopaedics, Division of Sports Medicine, University of Rochester Medical Center, Rochester, New York. Drs Chan and Goldblatt have no relevant financial relationships to disclose. Correspondence should be addressed to: John P. Goldblatt, MD, Department of Orthopaedics, Division of Sports Medicine, University of Rochester Medical Center, PO Box 665, 601 Elwood Ave, Rochester, NY 14642 ([email protected]). doi: 10.3928/01477447-20121120-31 DECEMBER 2012 | Volume 35 • Number 12 e1815 n Case Report our normal variants of menisco- meniscal ligaments have been re- Fported in the anatomy, arthroscopy, and radiology literature. The first and most prevalent is the anterior transverse menis- cal ligament, with a frequency of 58%.1 The second most frequently encountered variant is the posterior transverse menis- cal ligament, with a reported frequency of 1% to 4% .1,2 The last 2 variants include the medial and lateral oblique meniscomenis- cal ligaments, with a combined frequency of 1% to 4%.1,2 The oblique menisco- 1 2 meniscal ligaments run from the anterior Figure 1: Sagittal magnetic resonance image Figure 2: Coronal magnetic resonance image horn of 1 meniscus to the posterior horn showing a unilateral medial meniscomeniscal liga- showing a unilateral medial meniscomeniscal liga- ment (arrow) and adjacent normal structures. ment (arrow) and adjacent normal structures. of the opposite meniscus.3-5 The ligament is named for its anterior meniscal origin and has received increased attention be- cause it is often mistaken for a displaced bucket handle meniscus tear on magnetic resonance imaging (MRI). This article describes 2 patients with a unilateral variant to add to the 4 previously described normal variants. The difference between the oblique and unilateral menis- comensical ligaments is subtle and differs in their attachment to the posterior horn of the contralateral or ipsilateral meniscus. 3 Figure 3: Intraoperative arthroscopic image show- 4 ing the course of the medial meniscomeniscal liga- CASE REPORTS Figure 4: Sagittal magnetic resonance image ment (asterisk) from the anterior horn (AH) to the showing a unilateral lateral meniscomeniscal liga- Patient 1 posterior horn of the medial meniscus adjacent to ment (arrow) and adjacent normal structures. A 44-year-old woman presented with the medial tibial spine. Abbreviations: MFC, medial an approximately 3-month history of se- femoral condyle; MTP, medial tibial plateau.. vere knee pain localized to the medial joint line. She reported persistent pain The patient underwent surgical inter- recovery with full resolution of symp- while navigating stairs and with prolonged vention. Intraoperatively, the knee was toms. weight bearing. Her symptoms had been found to have a complex medial menis- managed conservatively with observation cus tear as demonstrated on the MRI and Patient 2 and physical therapy. was treated with a partial medial menis- A 14-year-old boy presented with Physical examination was significant cectomy. A unilateral meniscomeniscal right knee pain after sustaining a rota- for a moderate effusion with pain on ligament was also identified and traced tional injury during football practice. deep flexion. Medial joint-line pain was from the anterior to the posterior horn of On examination, the knee was ligamen- elicited with circumduction maneuvers. the medial meniscus (Figure 3). Although tously stable with a moderate effusion Magnetic resonance imaging revealed an the ligament was not attached to the in- but demonstrated medial joint-line ten- oblique tear of the posterior horn medial tercondylar spine along its entirety, mini- derness with circumduction maneuvers. meniscus. In addition, coronal and sagittal mal displacement occurred with probing. Magnetic resonance imaging findings in- MRIs demonstrated a rounded low-signal The ligament also resisted displacement cluded bony edema of the medial femo- structure arising from the anterior horn to the weight-bearing portion of the joint ral condyle, lateral tibial plateau, and a and inserting on the posterior horn of the and was deemed stable and left intact. blind-ending ligamentous structure adja- medial meniscus (Figures 1, 2). Postoperatively, the patient made a full cent to the intercondylar notch interpret- e1816 ORTHOPEDICS | Healio.com/Orthopedics UNILATERAL MENISCOMENISCAL LIGAMENT | CHAN & GOLDBLATT ed as a lateral meniscomeniscal ligament posterior horn of the lateral meniscus. They oblique and isolated unilateral variants so (Figure 4). cautioned that the oblique meniscomenis- as not to unnecessarily resect a normal The patient underwent conservative cal ligament mimicked the appearance structural variant and risk potentially management and had a quick recovery. At of a double posterior cruciate ligament causing further injury. 8-week follow-up, he had no mechanical sign on MRI and could thus be mistaken symptoms of locking or instability. for a bucket handle meniscus tear. Dervin REFERENCES and Paterson4 reported a similar case in a 1. Zivanovic S. Menisco-meniscal ligaments of DISCUSSION 41-year-old patient who was found to have the human knee joint. Anat Anz. 1974; 135(1- 2):35-42. The unilateral meniscomeniscal liga- an oblique meniscomeniscal ligament at the 2. Radoievitch S. Les ligaments des menisques ment is a relatively uncommon structure. time of arthroscopic intervention. They re- interarticulaires du genous. Ann Anat Path To the authors’ knowledge, it has not ported that the ligament could be mistaken Anat Normale Medico-Chirugicales. 1931; been previously reported in the anatomy, for an anterior cruciate ligament stump due 8:3-11. arthroscopy, or radiology literature. It ex- to its proximity to the anterior cruciate liga- 3. Sanders TG, Linares RC, Lawhorn KW, Tir- man PF, Houser C. Oblique meniscomenis- 4 tends from the anterior horn to the poste- ment as it traverses the intercondylar notch. cal ligament: another potential pitfall for a rior horn of the corresponding meniscus. Cadaveric studies have suggested in- meniscal tear–anatomic description and ap- pearance at MR imaging in three cases. Radi- Similar to the oblique meniscomeniscal creased excursion of the anterior horn of ology. 1999; 213(1):213-216. ligament, diagnostic imaging may mis- the medial meniscus at 30° of knee flexion 4. Dervin GF, Paterson RS. Oblique menisco- take this variant for a displaced bucket with transection of the anterior transverse meniscal ligament of the knee. Arthroscopy. handle meniscus tear due to its orienta- meniscal ligament, although the clinical 1997; 13(3):363-365. tion. However, the ligament is a distinct relevance is unknown.6,7 5. Kim HK, Laor T. Oblique meniscomeniscal ligament: a normal variant. Pediatr Radiol. structure with visible longitudinal fibers, 2009; 39(6):634. and it is resistant to displacement by ar- CONCLUSION 6. Muhle C, Thompson WO, Sciulli R, et al. throscopic probing. Similar to the oblique meniscomenis- Transverse ligament and its effect on menis- Sanders et al3 reported 3 patients with cal ligament, the exact function of the uni- cal motion. Correlation of kinematic MR im- aging and anatomic sections. Invest Radiol. oblique meniscomeniscal ligaments on lateral meniscomeniscal ligament is poor- 1999; 34(9):558-565. MRI, each traversing from the anterior ly understood. Surgeons should be aware 7. Tubbs RS, Michelson J, Loukas M, et al. The horn of the medial meniscus through the of the anatomic diversity of intermeniscal transverse genicular ligament: anatomical study intercondylar notch and inserting on the ligaments and the possible presence of and review of the literature. Surg Radiol Anat. 2008; 30(1):5-9. DECEMBER 2012 | Volume 35 • Number 12 e1817.