Hypermobile Meniscus


Clinically Relevant Anatomy[edit | edit source]

Axial view illustration of the anatomic relationships of the posterolateral meniscus.[1] Permission obtained by author.

Lateral meniscus hypermobility (LMH) is excess motion at the lateral meniscus (LM) that can cause lateral knee pain or tenderness, locking of the knee, or limitation of the range of motion during knee flexion. [2][3] It is a rare, uncommon condition. [2]

The menisci are crescent shaped, cartilaginous discs that lie between the articular cartilage of the femur and tibia. The menisci have various functions - load transmission, shock absorption, joint lubrication, nutrition, secondary mechanical stability, and guiding of movements.[4]

Anterior view illustration of the anatomic attachments to the posterolateral meniscus.[5] Permission obtained by author.

The LM is smaller, thinner, and more mobile than the medial meniscus. In addition, the LM has fewer anchoring stabilizers, most notably at its posterolateral aspect.[2] The anchoring stabilizers of the LM include capsular, fascicular, and ligamentous reinforcements. These anchoring stabilizers are the popliteomeniscal fascicles (PMF), the posterior capsule, the meniscofemoral ligaments, and the posterior meniscotibial ligament. [2] These attachments to the posterior knee prevent the subluxation of the posterior horn of the LM into the joint. [6]

Mechanism of Injury / Pathological Process[edit | edit source]

Posteromedial view illustration of the anatomic attachments to the posterolateral meniscus.[7] Permission obtained from author.

LMH relates to three different mechanisms: congenital deficiency in the capsular attachments[8], atraumatic injury to the ligamentous attachments[6], and trauma to those ligamentous attachments. Traumatic or atraumatic injury most often involve the PMF.[3]

Commonly, hypermobility is due to an atraumatic and/or overuse injuries. An isolated incidence of LMH is rare. Studies have found that concurrent damage to the PMF, which may result in LMH, occur in many cases of anterior cruciate ligament (ACL) and/or posterolateral injuries to the knee. [3]

Clinical Presentation[edit | edit source]

Symptoms include lateral knee pain, instability and painful popping or locking with the knee specifically in flexion and/or external rotation.[2]  Pain can be reproduced through application of a varus force at the knee with the hip placed in flexion and external rotation.(ie: Figure 4 or FABER position)[9] Case studies have demonstrated normal radiographs despite patients experiencing atraumatic, painful locking when sitting with legs crossed. [6][9]

Diagnostic Procedures[edit | edit source]

Arthroscopy is considered the gold standard of diagnosing LMH. An LMH diagnosis is confirmed if 50% of the LM crosses anterior to the midline of the tibial plateau. This is called a Gutter's Sign and is present in 95.5% of patients with LMH. To determine the level of hypermobility of the LM, an arthroscopic procedure is conducted to test for Gutter's Sign - a probe hooked behind the posterior lateral meniscus with anterior pressure causes translation of the LM beyond the tibial articular surface. [8]

The two main surgical techniques to stabilize the LM is to either suture the meniscal tissue to the anterior popliteomeniscal fascicle or fasten the LM to the posterior capsule of the knee.[2] There was an 82% success rate and 56% of participants returned to sport at the same performance level prior to injury according to a study that focused on suturing the LM to the posterior capsule, [10]

An MRI will show no abnormalities, but if an MRI is taken during the “locked” phase, you may see the posterior aspect of the LM anterior to the midline of the tibial plateau. This is indicative of LMH.[3]

Outcome Measures[edit | edit source]

Management / Interventions
[edit | edit source]

Early physical therapy interventions should focus on returning to full weight-bearing status and establishing early range of motion immediately following surgery. [11] The recommendation is to restrain weight-bearing past 90 degrees of knee flexion during the first 4 weeks post-surgery. Release to full activity and sport participation can occur at approximately 12 weeks post-surgery.[8] The treating clinician must consider the clinical evidence of the LM biomechanical functional capabilities during treatment to allow for full tissue healing and a safe return to activity.[11]

Goals of Rehab (0-3 weeks)[12]

  • Pain management
  • Promote tissue healing
  • Reduce swelling
  • Knee mobility
  • Restore full knee extension
  • Quadriceps activation
    • NMES


Goals of Rehab (3-6 weeks)[12]

  • Pain management
  • Promote tissue healing
  • Maintain full knee extension
  • Strengthening exercises
    • Minimal to Moderate Intensity


Goals of Rehab (6 weeks +)[12]

  • Establish normal gait pattern
  • Equal degrees of knee flexion compared to non-surgical limb
  • Progress strengthening exercises
  • Functional movement patterns
  • Return to Sport Training
    • Plyometrics
    • Agility
    • Straight-Line Running
  • Return to Sport Testing
  • Return to Sport Guidelines
    • No report of pain
    • No instability
    • No popping
    • No catching during deep knee flexion past 90 degrees

Differential Diagnosis
[edit | edit source]

Resources
[edit | edit source]

Meniscal Lesions Physiopedia Page

Arkansas Colleges of Health Education Musculoskeletal 1 PhysioPedia Project

MassGeneral Rehabilitation Guidelines for Athroscopic Meniscal Repair

References[edit | edit source]

  1. Aman ZS, DePhillipo NN, Storaci HW, Moatshe G, Chahla J, Engebretsen L, et al. Quantitative and qualitative assessment of posterolateral meniscal anatomy: Defining the popliteal hiatus, popliteomeniscal fascicles, and the lateral meniscotibial ligament. Am J Sports Med [Internet]. 2019;47(8):1797–803. Available from: http://dx.doi.org/10.1177/0363546519849933
  2. 2.0 2.1 2.2 2.3 2.4 2.5 1. Beel W, Macchiarola L, Mouton C, Laver L, Seil R. The hypermobile and unstable lateral meniscus: a narrative review of the anatomy, biomechanics, diagnosis and treatment options. Ann Jt [Internet]. 2022;7:14–14. Available from: http://dx.doi.org/10.21037/aoj-21-9
  3. 3.0 3.1 3.2 3.3 4. Kamiya T, Suzuki T, Otsubo H, Kuroda M, Matsumura T, Kubota C, et al. Midterm outcomes after arthroscopic surgery for hypermobile lateral meniscus in adults: Restriction of paradoxical motion. J Orthop Sci [Internet]. 2018;23(6):1000–4. Available from: http://dx.doi.org/10.1016/j.jos.2018.06.003
  4. Habegger A. The Knee. 2023 Mar.
  5. Aman ZS, DePhillipo NN, Storaci HW, Moatshe G, Chahla J, Engebretsen L, et al. Quantitative and qualitative assessment of posterolateral meniscal anatomy: Defining the popliteal hiatus, popliteomeniscal fascicles, and the lateral meniscotibial ligament. Am J Sports Med [Internet]. 2019;47(8):1797–803. Available from: http://dx.doi.org/10.1177/0363546519849933
  6. 6.0 6.1 6.2 McHugh C. Hypermobile lateral Meniscus [Internet]. Orthosports. 2022 [cited 2023 Mar 28]. Available from: https://orthosports.com.au/hypermobile_lateral_meniscus
  7. Aman ZS, DePhillipo NN, Storaci HW, Moatshe G, Chahla J, Engebretsen L, et al. Quantitative and qualitative assessment of posterolateral meniscal anatomy: Defining the popliteal hiatus, popliteomeniscal fascicles, and the lateral meniscotibial ligament. Am J Sports Med [Internet]. 2019;47(8):1797–803. Available from: http://dx.doi.org/10.1177/0363546519849933
  8. 8.0 8.1 8.2 8.3 Van Steyn MO, Mariscalco MW, Pedroza AD, Smerek J, Kaeding CC, Flanigan DC. The hypermobile lateral meniscus: a retrospective review of presentation, imaging, treatment, and results. Knee Surg Sports Traumatol Arthrosc [Internet]. 2016;24(5):1555–9. Available from: http://dx.doi.org/10.1007/s00167-014-3497-0
  9. 9.0 9.1 Nakashima H, Takahara Y, Uchida Y, Kato H, Itani S, Tsujimura Y, et al. Hypermobile anterior horn of the lateral meniscus: A case report and literature review. Case Rep Orthop [Internet]. 2020;2020:8870156. Available from: http://dx.doi.org/10.1155/2020/8870156
  10. Steinbacher G, Alentorn-Geli E, Alvarado-Calderón M, Barastegui D, Álvarez-Díaz P, Cugat R. Meniscal fixation is a successful treatment for hypermobile lateral meniscus in soccer players. Knee Surg Sports Traumatol Arthrosc [Internet]. 2019;27(2):354–60. Available from: http://dx.doi.org/10.1007/s00167-018-5080-6
  11. 11.0 11.1 Spang RC III, Nasr MC, Mohamadi A, DeAngelis JP, Nazarian A, Ramappa AJ. Rehabilitation following meniscal repair: a systematic review. BMJ Open Sport Exerc Med [Internet]. 2018;4(1):e000212. Available from: http://dx.doi.org/10.1136/bmjsem-2016-000212
  12. 12.0 12.1 12.2 Rehabilitation protocol for arthroscopic meniscal repair [Internet]. Massgeneral.org. [cited 2023 Mar 28]. Available from: https://www.massgeneral.org/assets/mgh/pdf/orthopaedics/sports-medicine/physical-therapy/rehabilitation-protocol-for-meniscus-repair.pdf