Isolated meniscal ramp lesion without obvious ACL rupture

Background To study isolated meniscal ramp lesion without obvious ACL analysis its clinical characteristics and evaluate clinical effect of all-inside horizontal mattress suture. Methods From 2015-2017, there are 20 isolated meniscal ramp lesion patients without obvious ACL rupture in our hospital. These isolated ramp lesions were arthroscopically repaired through all-inside horizontal mattress suturing method with 12 0 Mitek Omnispan meniscal repairing system. MRI was performed preoperatively and postoperatively 3 months later during follow-up. The Tegner-lysholm score and VAS score were recorded preoperatively and postoperatively at 2 years follow-up. T-test was performed to detect statistical significance. Results MRI postoperatively 3 months later shows healing of the isolated ramp lesion. Postoperatively at 2 years follow-up, VAS score was significantly decreased and Tegner-lysholm score was significantly raised comparing preoperatively. All patients recover their knee function without pain, including walking, stairs climbing and descending, squatting et al. Conclusion Isolated meniscal ramp lesion without obvious ACL rupture may exist because of ACL longitudinal splits. Through all-inside horizontal mattress suturing method with 12 0 Mitek Omnispan meniscal repairing system, isolated ramp lesion can be repaired through routine anterolateral and anteromedial portal. Our study shows isolated meniscal ramp lesion without obvious ACL rupture may exist because of ACL minor laxity caused by longitudinal splits. Through all-inside horizontal mattress suturing repair with Omnispan meniscal repairing system, isolated ramp lesions can be repaired through routine anterolateral and anteromedial portal and can heal with improved knee function and without posteromedial knee pain.

''ramp lesion'' was first described by Strobel in the 1980s [1], and useful for differentiating from other types of longitudinal posterior horn tears. These lesions have been reported in 15-17% of patients undergoing an ACL reconstruction [2,3,4].
Can Ramp lesion happened solely without obvious ACL rupture? There are no previous article reporting isolated ramp lesion without obvious ACL rupture. In our hospital, isolated ramp lesions without obvious ACL rupture were encountered. We retrospectively review clinical characteristics of these patients and arthroscopic repairing method. Ramp lesion was arthroscopically repaired through all-inside horizontal mattress suturing method with 12 0 Omnispan meniscal repairing system (Depuy Mitek Inc, Rayhanm MA, USA). Patients were evaluated postoperatively at 6 weeks, and at 3, 6, 12, and 24 months in outpatient clinic. The mean follow-up period is about 26 months. MRI was performed preoperatively and postoperatively 3 months later during follow-up ( Figure 1). The Tegnerlysholm score and Visual analogue scale (VAS) score were recorded preoperatively and in the last follow-up. T-test was performed to detect statistical significance between preoperative and the last follow-up.

Surgical method:
The knee joint was examined through anterolateral portal with 30 0 arthroscope by an experienced arthroscopic surgeon. The ACL integrity and tension was routinely checked through arthroscopic examination and probe tensioning. Usually some longitudinal spilt may be found without obvious ACL complete or partial rupture. In order to enlarge the posteromedial vision, the medial collateral ligament was pie-crust released with 5ml syringe needle in joint line percutaneously. Otherwise view of PHMM may be partly blocked by medial femoral condyle. With valgus and hyperextension of the knee, examination of the PHMM with meticulous probing were performed to find the ramp lesion.
If the probe hook tip (4mm length) can be inserted into meniscocapsular junction (meniscofemoral ligament) from upper surface of medial meniscus, it shows the ramp lesion of PHMM ( Figure 2). Because of tension of medial collateral ligament and convex contour of medial condyle, it is not easy to explore ramp lesion from routine anterolateral portal arthroscopically. Usually, we will explore and confirm ramp lesion through intercondylar notch view (between medial condyle and posterior cruciate ligament/PCL). To visualize the posteromedial compartment for inspection of meniscocapsular junction area, a 30 0 arthroscope was advanced through the intercondylar notch space [5]. A 70 0 arthroscope may be more helpful with wider vision. The posteromedial portal was created with 5ml syringe needle insertion into posteromedial compartment. The meniscocapsular junction of PHMM was examined with a probe to detect a ramp lesion through posteromedial portal. The meniscocapsular junction of PHMM may be easily visualized and confirmed through posteromedial view ( Figure 3). We utilize 12 0 Omnispan meniscal repairing system to perform all-inside horizontal mattress repair through anteromedial portal with anterolateral view. To facilitate the repairing procedure, the knee was placed in valgus and hyperextension position to avoid blocking of medial femoral condyle to the needle in the Omnispan applier. And medial collateral ligament piecrusting is also helpful to perform all-inside repairing procedure. Although it may be difficult, we perform all these ramp lesions repairing though the method successfully.
Rehabilitation procedure: Usually, we use knee brace for patients about 3 months during walking with crutches to prevent pivot shifting activity. In 6 weeks postoperatively, the knee is limited in 0 0 extension. After 6 weeks, the knee is limited in less than 60 0 flexion. On the first day postoperatively, patient begin straight leg raising exercise for improving quadriceps muscle strength and knee flexion/extension on bed. The knee flexion range is increased gradually on bed. After 2 weeks, knee flexion can be more than 90 0 . After 3-4 weeks, knee flexion can be more than 120 0 . Postoperatively 3 months later, with MRI proved healing of RAMP lesion, without knee pain and with full range of motion, squatting and jogging was permitted. With normal Single leg hop for distance (the distance hopped on the involved leg is more than 85% of the uninvolved leg) and negative Thessaly test, pivot activity at 6 months and full activity at 9 months were permitted.

Results
After 3 months, these patients manifest as no posteromedial pain in the knee. They can walk without knee brace or crutches supporting in daily life. After knee rehabilitation exercise, full range of motion can be acquired. But until 6 months postoperatively, pivot activity should be avoided to prevent retear of ramp area. With normal Single leg hop for distance and negative Thessaly test, pivot activity at 6 months and full activity at 9 months were permitted.

1.4)
points. The Tegner-Lysholm knee function score was raised from preoperative 35.6 (± 5.3) points to postoperative 85.7 (± 3.5) points. Both have statistical significance through Student's T test, shown in Table 1.  months after initial ACL injury. Patients younger than 30 years of age and male patients were more susceptible [3].
ACL rupture will increase tibial anterior translation and internal rotation, which make medial meniscus to ''engage'' the posteromedial femoral condyle and act as a wedge against the postero-medial tibia [6,7,8]. On the other hand, Hughston [9] suggested the presence of posteromedial tibial edema, and detachment between medial meniscus and joint capsule as the most significant indicator of a Ramp lesion [16].
These lesions are very peripherally located in the synovial sheath of posteromedial capsule. Their mobility at probing is very low. These characteristics make it possible to perform all-inside isolated ramp lesion repair with Omnispan meniscal repairing system through routine anterolateral and anteromedial portal. Because of longitudinal rupture of isolated ramp lesion, horizontal mattress suture can be performed to restore good stability. After 3 months, these patients can acquire healing of isolated ramp lesion ( Figure 1) because of good blood supply in Ramp region and good repairing stability.
Arthroscopy is considered gold standard for diagnosis of ramp lesions [18]. However, it is not without pitfalls [19]. Forty percent of ramp lesions are not identified through standard anterior portal visualization and inspection of the posterior compartment via a trans-notch view, and posteromedial probing is required to identify them [17,18].
Improved visualization through intercondylar view is key to (1)