Page 25 - 2020 ISAKOS Newsletter Volume I

CURRENT CONCEPTS
The maximum residual differences in knee kinematics in previous biomechanical studies assessing the effects of
meniscal ramp lesions are shown in Table I.
When comparing the degree to which knee kinematics are increased, it is important to evaluate the normal amounts of movement in ACL-intact and ACL-deficient knees. For example, previous research has shown that a side-to-side difference of >3 mm with maximum manual force (as applied with KT-1000 arthrometer) is indicative of a completely torn ACL. Therefore, the increases of 1 to 5 mm of ATT in association with the presence of meniscal ramp lesions in an ACL-intact knee that have been reported in the controlled laboratory setting may indeed have clinical implications.
TABLE I. Maximum Residual Differences in Knee Kinematics Among Biomechanical Studies Assessing Meniscal Ramp Lesions*
Surgical Treatment Strategies
Current surgical options for meniscal ramp tears include repair, trephination/rasping, and leaving the tear in situ. The chosen treatment depends on the size and stability of the tear as well as on adequate visualization to properly diagnosis the ramp-tear variant (e.g., meniscocapsular vs. meniscotibial). Some authors have advocated for the surgical repair of all meniscal ramp lesions at the time of ACLR on the basis of the potential increased risk of persistent instability and reconstruction graft failure when the tear is not treated. However, given the vascularization of the capsule and the red-red zone of the meniscus, some clinical studies have evaluated the potential for these tears to heal without surgical treatment following acute knee injuries.
Liu et al. evaluated the clinical outcomes for patients with ACLR and concomitant stable ramp lesions measuring <1.5 cm in length and reported no significant differences between trephination and meniscal repair after a mean duration of follow-up of 2 years. Those authors theorized that all meniscal ramp lesions measuring <1.5 cm in length were stable and thus may not require surgical repair with a concomitant ACLR. In contrast, Ahn et al. performed a clinical follow-up study with second-look arthroscopy and noted symptomatic and incomplete healing of meniscal tears at the meniscocapsular junction in 15% of patients with untreated ramp tears. As a result, they recommended that peripheral tears of the PHMM measuring >1 cm in length should be repaired during concomitant ACLR to decrease the rate of reintervention surgery and potentially protect the ACLR graft during primary ACLR.
There are two main reported techniques for repairing meniscal ramp lesions: (1) all-inside repair and (2) inside- out repair. Previous studies have demonstrated satisfactory clinical outcomes at a minimum of 2 years after combined ACLR and all-inside ramp repair. Sonnery-Cottet et al. reported an overall meniscal repair failure rate of 11% in patients who underwent combined ACLR and all-inside ramp repair via an accessory posteromedial portal. The proposed advantages of all-inside repair include no additional large incisions or the use of a single posteromedial portal, improved visualization of the PHMM when utilizing an accessory posteromedial portal, and potentially quicker surgical repair time. However, one disadvantage of all-inside repair via an accessory posteromedial portal is the inability to access tears involving the meniscotibial attachment or undersurface tears of the PHMM. Other disadvantages include the use of fewer sutures (resulting in a weaker repair), the risk of saphenous nerve and vein injury in association with the use of a posteromedial portal, and deployment of a surgical implant into the meniscus. Deployment of a surgical implant into the meniscus can be a major problem because it can cause further tearing of the meniscus and / or iatrogenic cartilage damage during or after deployment of the implant.
Study
ER (deg)
NR
ATT (mm)
Ahn et al.4 (2011)
5.2
Stephen et al.3 (2016) 2.5
Edgar et al.2 (2018)‡
1.7
NR
2.8
3.0
NR
Peltier et al.5 (2015)†
3.5
2.8
1.2
NR
*ATT = anterior tibial translation, IR = internal rotation, ER = external rotation, NR = not reported.
†Did not repair meniscal ramp lesion. ‡Did not cut ACL during testing.
The intuitive theories behind inherent knee instability and meniscal ramp lesions are becoming increasingly recognized. Biomechanical data have provided insight into the roles of both the meniscocapsular and meniscotibial attachments of the posterior part of the medial meniscus. Tearing of the superior meniscocapsular joint capsule or the inferior meniscotibial ligament may create further instability, with increased ATT and knee rotation. However, previous anatomical and histological analyses have shown that these two structures share a common PHMM attachment, and thus it has been theorized that the meniscocapsular and meniscotibial attachments may function together as an anatomical unit rather than as two independent structures. Our recent biomechanical study supported the aforementioned theory as the authors reported no significant differences in knee kinematics between meniscocapsular- based tears and meniscotibial-based tears in ACL-deficient and ACL-reconstructed knees.1 This finding suggests that although ramp lesions may occur in two separate locations instead of only at the meniscocapsular junction of the PHMM as previously described, an inside-out repair of the PHMM may be adequate to address lesions of both structures and restore knee stability.
IR (deg)
ISAKOS NEWSLETTER 2020: VOLUME I 23