Ramp Lesions of the Posterior Segment of the Medial Meniscus: What Is Repaired? A Qualitative Histological Study of the Meniscocapsular and Meniscotibial Attachments

Abstract

Background Lesions of the posterior segment of the medial meniscus are the most common intraarticular lesions associated with ACL injuries. Ramp lesions are tears in the peripheral attachment of the posterior horn of the medial meniscus. Such injuries are difficult to detect on preoperative MRI. Arthroscopically, the prevalence of these lesions can reach 24%. Anatomical descriptions of the posterior horn of the medial meniscus are becoming clearer, however, histological descriptions are lacking, especially with regard to the presence or absence of capillaries. Questions/purposes The present qualitative histologic study focused on the posterior segment of the medial meniscus and the meniscocapsular and meniscotibial junctions. Specifically, the objective of this study was to analyze the posterior segment of the medial meniscus and the meniscosynovial junction and to determine whether the meniscus tibial ligament exists. Methods We dissected 10 unpaired cadaveric knees (five male, five female, age range 55 to 66 years), five left and five right, from the French “Don du corps” body donation program via a posterior approach to the posteromedial capsule. We excluded specimens with intra-articular abnormalities (ACL rupture, meniscal tear, arthrosis) preceding dissection by arthrotomy. We thus accessed the posterior segment of the medial meniscus and the meniscosynovial junction. The proximal capsule, posterior segment of the medial meniscus, entire meniscal capsular-tibial junction, and a fragment of the tibia were removed en bloc. For each knee, three sagittal spaced sections of the posterior segment of the medial meniscus (Zone 4 as defined by Śmigielski) were performed. Two experienced pathologists performed qualitative histological analysis on the 30 samples after Hematoxylin and eosin staining, and Safranin O staining. Results Macroscopically, the meniscotibial attachments were pellucid and homogeneous, as were the meniscocapsular attachments; however, the meniscocapsular attachments appeared to be denser in both the anterior and posterior regions of the capsule. Microscopy of the meniscosynovial junction revealed loose collagen fibers that were partially oriented but not parallel, a cellular network featuring a few fibroblasts and adipocytes, and several capillaries. No between-attachment histologic differences were apparent; both tissues shared a site of attachment to the posterior horn of the medial meniscus. We did not detect the meniscotibial ligament, macroscopically or microscopically. Conclusions A ramp lesion may not be a ligamentous injury because the meniscotibial ligament was not detected. Rather, it appears that a ramp lesion is a tear in the common attachment point between the posterior horn of the medial meniscus and meniscocapsular and meniscotibial junctions. This structure is vascularized, and contains nonoriented low cellularity collagen of moderate density. Clinical Relevance Based on our results, a better rationale for the recommendation of surgical repair of a ramp appears to be needed, given the absence of a meniscotibial ligament, and the presence of capillaries in the meniscocapsular and meniscotibial attachments.

Leaving the stable ramp lesion unrepaired does not negatively affect clinical and functional outcomes as well as return to sports rates after ACL reconstruction

“…Attention focused on ramp lesions of the medial meniscus has dramatically increased in the past decade [5, 10, 15, 18, 20]. The epidemiological characteristics of ramp lesions and short‐term to mid‐term clinical outcomes of ramp lesion repair have been investigated by previous studies [6, 18].…”

Ligamento meniscotibial medial do joelho: Uma dissecção passo a passo

“…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.…”

“…Recentemente, Di Francia et al 15 descreveram uma abordagem posterior direta pela fossa poplítea, identificando, isolando e seccionando os músculos isquiotibiais e gastrocnêmios. Isso revelou a cápsula posterior do joelho, que foi aberta em sua porção mais proximal, permitindo o acesso ao segmento posterior do menisco medial.…”

Ramp lesion in anterior cruciate ligament injury: a review of the anatomy, biomechanics, epidemiology, and diagnosis

“…[ 24 ] Di Francia et al. [ 28 ] Laboratory Laboratory Anatomic Laboratory Laboratory 14 14 NR 4 10 36.4% within the total PHMM height Superior edge of PHMM No attachment (free superior edge of PHMM) No attachment (free superior edge of PHMM) Common junction (PM capsule, MTL, PHMM) Common junction (PM capsule, MTL, PHMM) Inferior edge of PHMM Inferior edge of PHMM Solidly anchored to PHMM Common junction (PM capsule, MTL, PHMM) MTL meniscotibial ligament, N number of cadaveric knees, NR not reported, PHMM posterior horn of medial meniscus, PM posteromedial …”