Retrospective evaluation of MRI findings in arthroscopically confirmed cases of hypermobile lateral meniscus.

OBJECTIVE: To identify preoperative MRI findings in patients with arthroscopically confirmed hypermobile lateral meniscus utilizing a standard MRI knee protocol, with comparison to normal control and lateral meniscal tear groups. SUBJECTS AND METHODS: All patients with arthroscopically confirmed hypermobile lateral meniscus diagnosed at our institution were retrospectively identified. The following structures were evaluated on preoperative knee MRIs: superior and inferior popliteomeniscal fascicles, lateral meniscus and meniscocapsular junction, popliteal hiatus, and soft tissue edema around the popliteal hiatus. The same MRI features were evaluated in the normal control and lateral meniscal tear groups. RESULTS: Study, normal control, and lateral meniscal tear patients (18 each) were included. In the study group, 94.4% had superior popliteomeniscal fascicle abnormality, 89.0% had inferior popliteomeniscal fascicle abnormality, and 72.2% had lateral meniscal abnormality. Incidence of these abnormalities was significantly higher than in the normal control group. Meniscal abnormalities in the study group all involved the posterior horn meniscocapsular junction, 12/13 of which had vertical signal abnormality at the junction and 1/13 with anterior subluxation of the entire posterior horn. Popliteus hiatus measurements were largest in the lateral meniscal tear group. CONCLUSION: In patients with hypermobile lateral meniscus, the combination of popliteomeniscal fascicle abnormality and vertical signal abnormality at the meniscocapsular junction was seen in the majority of patients. Popliteomeniscal fascicle signal abnormality without identifiable lateral meniscal injury was the next most common imaging appearance. Radiologists may provide valuable information by suggesting the diagnosis of hypermobile lateral meniscus in such cases.

Hypermobile lateral meniscus: A systematic review of current treatment options.

PURPOSE: The reliable data on the incidence of hypermobile lateral meniscus (HLM) and its clinical manifestations, diagnostic methods and therapeutic approaches are limited. This systematic study aimed to review available treatment options for HLM and the outcomes of each approach. METHODS: A systematic search was performed in four electronic databases (PubMed, EMBASE, Scopus, Web of Science) to identify studies in which arthroscopically confirmed cases of HLM were treated surgically or nonsurgically, and the required data comprising study characteristics, patient data, treatment approaches and outcome measures were extracted from eligible studies. RESULTS: Twenty studies with a total of 212 patients (138 males and 74 females) and 219 knees were included. The most frequently reported symptoms were locking sensations, knee pain, giving way and snapping. Treatments used by the studies were: radiofrequency energy in two studies; arthroscopic partial meniscectomy in one study; open surgery in two studies; and arthroscopic meniscal repair in 17 studies. Eleven studies used an all-inside repair method and an inside-out meniscal repair was reported in eight studies. Three studies reported the usage of posterior arthroscopy for therapeutic or diagnostic approaches. Evaluation of symptom resolution was the main outcome measurement for which almost all of the studies stated relief of symptoms after intervention. CONCLUSION: Despite the lack of definite consensus about the most appropriate intervention for HLM, therapeutic preference was directed towards arthroscopic all-inside and inside-out repair techniques. Although the surgeon's decision remains the key factor in choosing the most suitable treatment option for each individual, posterior arthroscopic meniscal repair may be considered as a better option for HLM treatment according to the findings of this review. LEVEL OF EVIDENCE: Level IV.

Morphology of the popliteomeniscal fascicles around the popliteal hiatus on three-dimensional images reconstructed from 7 T magnetic resonance imaging: A cadaveric study.

BACKGROUND: This study aimed to clarify the characteristic features of the anteroinferior and posterosuperior popliteomeniscal fascicles (aiPMF and psPMF, respectively) and popliteal hiatus using three-dimensional (3D) reconstructions of 7 T magnetic resonance imaging (MRI) arthrography. METHODS: Six knees from human cadavers fixed using the Thiel embalming method were examined using 7 T MRI arthrography. 3D Images of the structures around the popliteal hiatus were reconstructed. Morphologies of the psPMF, aiPMF, and popliteal hiatus were investigated and their positional relationships analyzed. RESULTS: The PMFs attached to the periphery of the lateral meniscus (LM) to form the popliteal hiatus. Each coursed in an oblique direction. The mean length of the psPMF and aiPMF attachments to the LM were 6.8 and 21.6 mm, respectively; mean popliteal hiatus length was 12.8 mm. These lengths corresponded to 7.5%, 24.3%, and 14.5% of the total length of the LM, respectively. The aiPMF was thick near the lateral aspect of the articular capsule and became thinner towards the posteromedial aspect of the LM. The psPMF was thick near the posterior aspect of the articular capsule and became thinner towards the posterolateral aspect of the LM. CONCLUSION: Morphological properties of the aiPMF, psPMF, their attachments to the LM, and the popliteal hiatus were consistent across the cadaver specimens examined. Each PMF was thin near the popliteal hiatus and became thicker towards its attachment to the articular capsule. These findings may be useful for anatomical repair for the LM hypermobility.

Repair of popliteomeniscal fascicles tear using a posterior transseptal portal fixes hypermobile lateral meniscus.

PURPOSE: This study investigates the effects of the all-inside repair of posterosuperior popliteomeniscal fascicle (PMF) on lateral meniscus stabilization using a posterior arthroscopic approach. METHODS: Between 2015 and 2018, 17 patients with hypermobile lateral meniscus (HLM) underwent posterior knee arthroscopy for PMF repair. The all-inside repair was performed through posteromedial transseptal and posterolateral portals using a suture hook technique. Patients were clinically assessed based on IKDC and Lysholm scores. RESULTS: Both IKDC and Lysholm scores improved significantly after an average follow-up of 3.5 years (P < 0.001). No patients underwent reoperation, and no complications associated with posterior knee arthroscopy were reported. CONCLUSION: The all-inside suture hook technique using posterolateral and posteromedial transseptal portals fixes HLM with excellent IKDC and Lysholm scores. LEVEL OF EVIDENCE: Level IV.

Preoperative Magnetic Resonance Imaging as a Diagnostic Aid for Hypermobile Lateral Meniscus.

BACKGROUND: Hypermobile lateral meniscus is difficult to diagnose with imaging due to its absence of tears or anomalies. We aimed to clarify the accuracy of the preoperative diagnosis using magnetic resonance imaging (MRI). METHODS: The preoperative MRI status of the posterosuperior popliteomeniscal fascicle (sPMF), anteroinferior popliteomeniscal fascicle (iPMF), and popliteal hiatus were examined retrospectively on sagittal images in the hypermobile lateral meniscus group (n = 22) and an age- and gender-matched control group (n = 44). These statuses were evaluated by a logistic regression analysis to assess their degree of diagnostic accuracy. RESULTS: The area under the curve (AUC) of the sPMF, iPMF, popliteal hiatus, and all three criteria combined was 0.66, 0.74, 0.64, and 0.77, respectively (low, moderate, low, and moderate accuracy, respectively). The odds ratios of the most severe type 3 forms of the sPMF, iPMF, and popliteal hiatus for hypermobile lateral meniscus were significantly high (5.50, 12.20, and 5.00, respectively). Although the diagnostic accuracy was not high enough, the significantly higher odds ratio for type 3 may indicate a hypermobile lateral meniscus. CONCLUSION: a definitive diagnosis of hypermobile lateral meniscus is difficult with MRI findings alone; however, MRI evaluations of the iPMF, sPMF, and the widening of popliteal hiatus can be used as an adjunct to diagnosis.

The aspiration test: an arthroscopic sign of lateral meniscus posterior horn instability.

The suspensory mechanism of the posterior horn of the lateral meniscus (PHLM) is an anatomically complex structure including the popliteomeniscal fascicles, the meniscotibial posterior root attachment and the meniscofemoral ligaments. Damage to one or several of these structures - either through knee trauma or congenital abnormalities-can result in an instability of the PHLM that may lead to lateral knee pain, locking sensations or lack of rotational control of the knee (e.g. after anterior cruciate ligament injuries). The diagnosis of PHLM instability is complex due to the lack of reliable clinical tests and imaging signs. Direct visual dynamic inspection via arthroscopy thus remains the gold standard. However, arthroscopic probing of the PHLM is not always reliable and the precise quantification of the amount of subluxation of the PHLM can be difficult. Therefore, the main objective of this report was to describe a quick and easy arthroscopic screening test called "the aspiration test" in order to help surgeons to detect PHLM instability. During the exploration of the lateral tibiofemoral compartment with the knee kept in the figure of 4 position, the arthroscope is placed in the antero-lateral portal and directed towards the lateral tibiofemoral compartment. The aspiration test is then performed by activating the aspiration of the 4-mm shaver when located in the intercondylar notch. In case of a PHLM instability, an excessive displacement of the PHLM is observed. After repair, a second aspiration test allows to verify that the PHLM has been stabilized.

An isolated Posterolateral corner injury with rotational instability and hypermobile lateral meniscus: a novel entity.

PURPOSE: Although complete tear of the knee posterolateral corner (PLC) commonly occurs in combination with other knee ligamentous injuries, the incidence of isolated PLC injury was reported only 28% and overlooked in many cases. Nevertheless, an isolated PLC injury does not only provoke posterolateral instability, but also may be associated to hypermobile lateral meniscus. This study aims at showing the characteristics of isolated PLC injuries and to alert potential overlooked cases by describing their arthroscopic findings and clinical characteristics. METHODS: Seventy-one patients with a clinically proven isolated PLC injury who underwent knee arthroscopy were included in this study. Pre-operative symptoms and clinical signs at examination were recorded: Pain at the posterolateral aspect, feelings of instability, catching, locking; and for clinical signs: McMurray test, varus stress test in extension and at 30° of flexion, posterolateral drawer test at 30° and 80°, dial test at 30° and 80° of flexion. In terms of arthroscopic findings, systematic meniscal stability was performed to evaluate the presence of hypermobile lateral meniscus, "lateral drive through test" was also recorded in all cases. RESULTS: Positive Lateral Drive through test was found in 69 patients (95.8%). Hypermobile lateral meniscus was seen in all patients. CONCLUSIONS: Hyper mobile lateral meniscus was concomitant with all isolated PLC injuries in our case series. As the typical arthroscopic characteristic, lateral drive through test positive were seen in 95.8%. In order to prevent overlooking this concomitant pathology, meticulous arthroscopic observation is crucial. LEVEL OF EVIDENCE: Level IV.

MR Imaging of the Hypermobile Lateral Meniscus of the Knee: A Case Report.

OBJECTIVE: The hypermobile lateral meniscus of the knee is a rarely described entity. In this case report we aim to draw attention to the clinical presentation and MR imaging findings of this pathology. CASE REPORT: We review the clinical and imaging findings that led to the diagnosis of hypermobile lateral meniscus with transient subluxation causing intermittent locking, and which subsequently led to successful surgical treatment. CONCLUSION: Hypermobile lateral meniscus is rarely diagnosed prospectively on MR imaging. A better understanding of this uncommon condition will lead to prompt diagnosis and effective treatment, with a better outcome for the patient.

Menisco lateral hipermóvil: diagnóstico y tratamiento de lesiones de fascículos poplíteo meniscales / Hypermobile lateral meniscus: diagnosis and treatment of popliteomeniscal fasciculi injuries

El Síndrome de Menisco Hipermóvil, caracterizado por bloqueos mecánicos dolorosos de la rodilla, tiene un sustento anatómico basado en los fascículos poplíteo meniscales anteroinferior y posterosuperior, responsables de la estabilidad primaria de la esquina posterolateral meniscal. Con un cuadro clínico característico, usualmente con Resonancia Magnética sin hallazgos sugerentes de patología, la artroscopía juega un rol esencial en casos de alta sospecha, comprobando el diagnóstico al presentar hipermobilidad del cuerno posterior del menisco lateral. MÉTODO: Se presentan 9 casos resueltos, con hiperlaxitud posterolateral meniscal, y presentación clínica caracterizada por bloqueo articular de rodilla sin causa aparente. En todos los casos se realizó reparación de los fascículos poplíteo meniscales con suturas meniscales, con resolución completa de la sintomatología y sin complicaciones post quirúrgicas. CONCLUSIÓN: El manejo del cuadro de menisco hipermóvil está basado por la sospecha clínica y el descarte de otras patologías como causa subyacente de la sintomatología. El manejo quirúrgico con suturas meniscales ha demostrado restaurar la biomecánica normal del compartimento posterolateral de la rodilla, logrando la resolución completa de los síntomas. NIVEL DE EVIDENCIA: IV.

Hypermobile Meniscus Syndrome, characterized by painful mechanical blockages of the knee, has an anatomical support based on the anteroinferior and posterosuperior poplíteomeniscal fascicles, responsible for the primary stability of the posterolateral meniscal corner. With a characteristic clinical presentation, usually with Magnetic Resonance without suggestive findings of pathology, arthroscopy plays an essential role in cases of high suspicion, checking the diagnosis by presenting hypermobility of the posterior horn of the lateral meniscus. METHOD: We present 9 resolved cases, with posterolateral meniscal hypermobility, and clinical presentation characterized by knee articular block without apparent cause. In all cases, poplíteomeniscal fascicles were repaired with meniscal sutures, with complete resolution of the symptoms and without post-surgical complications. CONCLUSION: The management of the hypermobile meniscus syndrome is based on clinical suspicion and the discarding of other pathologies as the underlying cause of the symptomatology. Surgical management with meniscal sutures has been shown to restore the normal biomechanics of the posterolateral compartment of the knee, achieving complete resolution of symptoms. LEVEL OF EVIDENCE: Case series IV.