What did the study look at?
The menisci are crescent-shaped, cartilage-like structures between the thigh bone and shin bone in the knee joint. They deepen the joint surface, transmit load, absorb shock and help stabilise the knee. The authors note a growing trend over the past decade to save the meniscus whenever possible.
The aim of this review was to summarise the anatomy, biomechanics and movement characteristics (kinematics) of the meniscus to guide surgeons during meniscal repair.
How was it done?
This is a review article: the authors did not carry out a new experiment or patient study but brought together earlier anatomical, cadaveric, laboratory and clinical work. Topics covered include the size and zones of the menisci, their root attachments, links with surrounding ligaments, tissue composition, embryological development, blood supply and the biomechanical effects of different tear types.
What did it find?
The main points reported in the review are:
- Size: the medial meniscus is about 45.7 mm long and 27.4 mm wide, and the lateral meniscus about 35.7 mm long and 29.3 mm wide. Because of its thinner, more elastic attachments, the lateral meniscus is more mobile than the medial one.
- Roots: the meniscal roots convert axial load into hoop stress and stop the meniscus being pushed out of the joint (extrusion). A root tear can raise contact pressures to levels similar to removal of the whole meniscus.
- Composition: the meniscus is roughly 70% water and 30% organic material; collagen makes up 75% of its dry weight.
- Blood supply: vessels reach the outer 20-30% of the medial meniscus and the outer 10-25% of the lateral meniscus; the centre is largely avascular. However, a recent study is cited that found vessels and progenitor cells in the so-called "white-white" zone.
- Load sharing: the meniscus carries 70% of the load in the lateral compartment and 50% in the medial compartment.
- Tear types: a cadaveric study reported a 70% rise in contact pressures with horizontal cleavage tears; removing one leaflet increased pressure by 33-46% and removing both by 75-79%. Large radial tears and root tears can be functionally equivalent to removing the whole meniscus.
- Walking and movement: the studies reviewed reported increases in measures reflecting load on the inner side of the knee after partial meniscectomy, which were not seen in repair groups.
The authors' conclusion
The authors conclude that meniscal tears can cause serious functional, biomechanical and kinematic disturbances in the knee, leading to faster degeneration of joint cartilage. A sound understanding of how the meniscus and its attachments relate to key arthroscopic landmarks allows the surgeon to repair meniscal problems anatomically and restore the knee's natural biomechanics.
Reference
Mameri ES, Dasari SP, Fortier LM, Verdejo FG, Gürsoy S, Yanke AB, Chahla J. (2022). Review of Meniscus Anatomy and Biomechanics. Current Reviews in Musculoskeletal Medicine, 15(5), 323-335.
DOI: 10.1007/s12178-022-09768-1
Free full text: PubMed Central (PMC9463428)
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
