Medial meniscus tears requiring surgical interventions are mostly being done by arthroscopic procedures. During the arthroscopy, accessing the medial joint space is challenging. Because of this situation, pie-crusting of the medial collateral ligament (MCL) of the knee is described. This procedure is to release the MCL 1 cm distal to its origin with a needle-tip. This release provides enough space for both identifying the tear and also provides enough space to introduce necessary equipment in the joint space for repair. But there are some doubts about MCL release. Some authors suspected ongoing valgus instability after this procedure. Our aim is to identify the tension of MCL with USG shear wave elastography before the procedure, and 3 weeks, 6 weeks and 3 months postoperatively.

Meniscal lesions are common orthopedic injuries. Posterior horn and medial meniscus root injuries are frequently seen as isolated cases or in association with ligament injuries ( 1 , 2 ). Arthroscopy is the preferred treatment method, and proper visualization of the medial compartment of the knee is crucial for correct diagnosis and treatment. Arthroscopic visualization of the posteromedial aspect of the knee may be difficult in patients with medial narrow knee joints and no ligament injuries ( 1 , 2 ); inadequate visualization may lead to treatment failure with persistent symptoms such as pain, crepitation, or locking of the joint. Femoral or tibial cartilage damage may occur during arthroscopy due to the narrowness of the medial compartment of the knee, due to the instruments used, which may lead to secondary osteoarthritis or to rupture of the medial collateral ligament (MCL) during valgus stress if excessive force is applied to open the medial joint space. During difficult manipulations, damage and breakage of arthroscopic instruments may occur. Therefore, in order to optimize imaging and intervention in medial knee joint pathologies, it is recommended to perform prophylactic controlled percutaneous needle-assisted loosening of the superficial medial collateral ligament during the operation (pie-crusting). However, there is a concern that the medial collateral ligament may not heal and laxity may develop. There are studies in the literature on patients who underwent medial collateral ligament loosening with the piecrusting method. In these studies, improvement has been shown in functional scores, physical examination (valgus stress), magnetic resonance imaging and knee valgus stress radiographs. However, the healing time and whether the medial collateral ligament has regained its former morphological characteristics have not been quantitatively demonstrated.

Share wave elastography uses sound waves to evaluate the mechanical properties of tissues such as stiffness and elasticity. They are used to detect different pathologies in tissues by using the differences in the mechanical properties mentioned above. Tissue stiffness is calculated using a physical property of tissue called Young's modulus or modulus of elasticity. Young's modulus is defined as the ratio of stress (force applied to the cross-sectional area of a given material) to strain (i.e., deformation; in this case, tissue deformation). The unit of Young's modulus is Pa (Pascal) or the SI unit is N/m2. The sonographic elastography value is usually in kPa (kilopascal) in most clinical settings. Patients who are scheduled for surgery with a diagnosis of medial meniscus tear will be evaluated ultrasonographically by 2 different radiologists in the preoperative period. Both knees will have medial collateral ligament share wave elastography performed and recorded. In patients who have undergone medial collateral ligament pie crusting for imaging of the knee medial compartment during the operation, share wave elastographic measurements will be performed by the same 2 radiologists again in the 3rd, 6th and 12th weeks after the operation. At the same time, the functional scores and examination findings of these patients in their outpatient clinic follow-ups will be noted. Preoperative and contralateral knee medial collateral ligament measurements of the patients will be used as the control group.

Inclusion Criteria:

• Being 18 years of age or older
• Having a medial meniscus laceration detected in the magnetic resonance imaging taken due to the application for knee complaints and therefore having an indication for surgery
• Having consented to the surgical consent form explaining surgical and non-surgical options, accepting the surgical procedure
• Having consented to the research volunteer consent form presented to him/her verbally and in writing after giving his/her consent for surgery

Exclusion Criteria:

• Having had a previous fracture, meniscus tear, anterior or posterior cruciate ligament tear, medial or lateral collateral ligament tear in the same or opposite knee.
• Having had arthroscopic or open surgery around the knee due to or outside of the above reasons.
• Having had or not had surgery on the same lower extremity or the opposite lower extremity, having a fracture sequela or deformity.
• Having grade 1 or higher arthrosis according to the Kellgren-Lawrence arthrosis classification on direct radiographs taken before surgery.
• Patients who do not require medial collateral ligament release to access the medial joint space during surgery and therefore do not require pie-crusting medial collateral ligament release.
• Patients who wish to withdraw their consent given to the research volunteer consent form at any time during the study.

Patients with medial meniscal injury

During the writing process of the research, the age, operated side, preoperative value and postoperative follow-up values of shear wave elastographys are planned to be shared with the other researchers in the article.