Keywords
ligaments - menisci, tibial - dissection
Introduction
The menisci are fibrocartilaginous structures that provide important functionalities
to the biomechanical complex of the knee, such as axial and tension forces, cushioning,
synovial fluid distribution and an increase in articular surface area between the
tibia and femur.[1]
[2]
[3]
[4] These structures are attached to the knee by meniscocapsular ligaments, which contain
meniscofemoral and meniscotibial (MTL) components.[1]
[5]
[6]
Peltier et al.[7] described the importance of MTLs for knee stability, especially for posteromedial
rotation stability. MTL lesion is a common cause of knee pain in middle-aged athletes.[8] In addition, MTLs, particularly the medial meniscotibial ligament, exhibit synergic
action with the anterior cruciate ligament (ACL), primarily for rotation stability,
anterior translation and internal and external rotations, clinically confirmed by
the rotational test during physical examination.[7]
Considerable attention has been paid to MTLs, also known as coronary ligaments, especially
after the “Save the Meniscus” initiative gained importance among knee surgeons. Technically
challenging, the diagnosis and treatment of ramp lesion show the importance of MTLs.[1] These ligaments were discovered long ago, but their contribution to knee stability
has only recently been studied and still lacks information.[1]
Thus, the aim of the present study was to describe step-by-step an dissection technique
of the medial LMT, efficient, reproducible and that may lead to further research.
Methods
The present study was approved by the Research Ethics Committee (protocol number:
27128619.6.0000.5047). Twenty fresh cadaver knees were used, with no preference for
sex or age. The corpses were selected by the Intrahospital Commission on Organ and
Tissue Donation for Transplants.
Exclusion criteria were cadavers with traumatic signs or degenerative lesion around
the knee that would hinder medial MTL dissection. However, none of the selected cadavers
were excluded.
All the knees were dissected using the same technique to determine the incidence of
medial MTLs, thereby maintaining standards important to the study conclusions.
Results
The cutaneous incision starts in the topography proximal to the medial epicondyle
toward the posterior edge of the tibia ([Fig. 1A]). After dieresis of the skin and subcutaneous cell tissue, the crural fascia was
identified inferiorly to the sartorius fascia ([Fig. 1B]).
Fig. 1 Access for exeresis of the medial MTLs. (A) The cutaneous incision starts in the topography proximal to the medial epicondyle
toward the posterior edge of the tibia. (B) First medial layer of the knee. (P: Patella; AL: Articular Line; F: Femur; T: Tibia;
FA: Sartorius Fascia; *: Cutaneous Incision).
After the longitudinal incision on the crural fascia is made, it is possible to observe
the superficial medial collateral ligament (MCL) and articular line (AL) ([Fig. 2]). After distally releasing the superficial MCL, we can identify the capsule of the
knee joint (known as the third layer, according to Warren and Marshall[9]), which becomes thicker and forms a vertically oriented band of short fibers known
as the deep MCL. This, in turn, extends from the femur to the medial portion of the
peripheral margin of the meniscus and tibia.
Fig. 2 Access for exeresis of the medial MTLs. Second medial layer of the knee. Needles
demonstrate the exact position of the articular line. Medial collateral ligament between
the needles (Red asterisk: 25 × 7mm needles; Blue asterisk: medial collateral ligamentl).
Anteriorly, the deep MCL is clearly separated from the superficial MCL by an interposed
pouch. Posteriorly, however, the layers join because the meniscofemoral portion of
the deep MCL tends to merge with the overlying superficial MCL in the region near
cephalic fixation. The meniscotibial portion of the deep MCL, however, is immediately
separated from the overlying superficial MCL and is referred to as the coronary ligament,
that is, part of the medial MTL itself. Thus, identifying the deep MCL is an excellent
reference to identify the medial MTL and its meniscal and tibial insertions ([Fig. 3]).
Fig. 3 Access for exeresis of the medial MTLs. Third medial layer of the knee. Medial collateral
ligament displaced proximally, to enable visualization of the medial meniscus and
medial MTL (inserted). (MCL: Medial collateral ligament; MTL: Meniscotibial ligament;
MP: Medial plateau; MM: Medial meniscus).
The tibial insertion of the MTL is released and the meniscus proximally displaced,
revealing the entire extension and length of the medial MTL ([Fig. 4]).
Fig. 4 Access for exeresis of the medial MTLs. Third medial layer of the knee. Medial MTL
insertion (displaced proximally). (MTL: Medial tibial meniscus ligament; MM: Medial
meniscus; MFC: Medial femoral condyle; MP: Medial plateau; C: Cartilage).
In all the cadavers, we observed that this ligament exhibits vast meniscal and tibial
interdigitation.
A transverse incision is made in the meniscal and tibial insertions, highlighting
the entire medial MTL ([Fig. 5])
Fig. 5 Access for exeresis of the medial MTLs. Disinsertion of the medial MTL of the medial
meniscus and its tibial insertion (MTL: Medial tibial meniscus ligament; MM: Medial
meniscus; MFC: Medial femoral condyle; MP: Medial plateau).
The medial MLT was found in all 20 knees studies using the aforementioned technique.
In our sample, the medial MTL exhibited an average length of 70.0 ± 13.4 mm and width
of 32.25 ± 3.09 mm, thickness of 35.3 ± 2.7 mm and weight of 0.672 ± 0.134 g. In all
the cases, the origin of the medial MCL was proximal and deep in relation to the deep
MTL in the tibia.
Discussion
Clinical and anatomical studies of the MTL have increased significantly in recent
years. However, a thorough understanding of the anatomy via well performed or standardized
dissections is essential to manage surgeries and conduct additional research. However,
information on medial MTLs is limited, primarily with respect to anatomical dissection.
In 2010, Fang et al.[10] dissected 10 cadavers, initially identifying the superficial MCL and the deep MCL
from their femoral and tibial insertions. The anatomy of the deep MCL was analyzed
in two parts: meniscofemoral and meniscotibial ligaments, with a description of the
length, insertion site and relationship with the meniscus. Cavaignac et al.[11] studied 14 cadavers and described a dissection with disinsertion of goose foot tendons,
sectioning the medial gastrocnemius tendon up to its femoral insertion to release
the posterior capsula and disinsert the femur from the vastus medialis muscle. A single
anatomical part was collected from each cadaver, including the medial condyle, medial
tibial plateau, medial meniscus, cruciate ligaments, articular capsule and distal
insertion of the semimembranosus. In all the cases, macroscopic examination revealed
a structure corresponding to the meniscotibial ligament, inserted into the inferior
part of the medial meniscus, specifically at the posterior-inferior border.
In a study on the anatomy of the posterior medial meniscus, DePhillipo et al.[12] described a dissection in which all the soft tissues were removed 10 cm distal and
proximal to the articular line, and whole structures of the posteromedial corner were
left intact. Analysis revealed a common attachment between the insertion of the medial
meniscus ligament and meniscocapsular insertion in the posterior horn of the medial
meniscus.
Griffith et al.[13] dissected 24 cadaver knees, highlighting the semitendinosus, gracilis and sartorius
muscles and tendons, and isolating, in a deeper dissection, the proximal and distal
divisions of the superficial MCL, posterior oblique ligament and the meniscofemoral
and meniscotibial divisions of the deep MCL. DePhillipo et al.[14] described a posterior longitudinal approach with the dissection made between the
heads of the gastrocnemius muscles, locating the MTL medial to the tibial facet of
the posterior cruciate ligament, 1.5 cm distal to the articular line. A 2007 study[2] dissected 85 knees, finding MTLs in only 23.5%, and two different insertions in
each.
Di Francia et al.[15] recently described a direct posterior approach via the popliteal fossa, identifying,
isolating and sectioning the ischiotibial and gastrocnemius muscles, revealing the
posterior capsula of the knee, which was opened at its most proximal part, allowing
access to the posterior segment of the medial meniscus. Histological analysis found
no ligament structure corresponding to the MTL.
The present study presented a large number of patients studied when compared with
others on the same topic. LaPrade et al.[16] dissected 8 cadaver knees to study the anatomy of the medial part of the knee. El-Khoury
et al.[17] dissected 10 knees, 4 from adult cadavers and 6 from dead fetuses, to study ruptures
of the MTL. Liu et al.[10] studied the knees of 10 cadavers to describe the morphology of the medial collateral
ligament. Griffith et al.[13] dissected 24 cadavers to assess the biomechanical correlation of the medial knee
structures. Few studies, however, provide a detailed description of the anatomical
dissection procedure.
Conclusion
We describe a simple effective and reproducible medial MTL dissection technique that
makes it possible to identify the ligament over the entire medial extension of the
knee.
