The meniscus is divided into the medial and lateral parts. Each meniscus can be further divided into the anterior horn, the body, and the posterior horn. The tears in different regions have significant differences in terms of anatomical structure, blood supply conditions, and mechanical environment, presenting distinct challenges for the design of meniscus repair needles and the operation techniques. Understanding these differences is the key to mastering the meniscus repair technique.

Posterior horn tear is the most common and challenging type. The posterior horn of the medial meniscus is adjacent to the posterior cruciate ligament and the popliteal tendon, and the space is extremely narrow. Traditional suture techniques are difficult to perform here. The advantages of the meniscus repair needle are fully demonstrated here: the slender needle body can bypass the medial femoral condyle and precisely reach the posterior horn tear site under arthroscopic monitoring. Due to the special anatomy of the posterior horn, some repair needles are designed with a pre-bent angle (usually 15° - 25°), allowing the needle tip to naturally align with the tear surface. During the operation, the doctor needs to place the knee in the "4-point position" (hip externally rotated and abducted, ankle placed on the opposite knee) to expand the posterior medial gap and create an operating space for the repair needle.

The treatment of the body part tear is relatively easier, but the required fixation strength is the highest. The body part of the meniscus bears most of the axial load, and the sutures here need to withstand tensile forces of over 100 Newtons. When repairing a tear in the body part of the meniscus, the meniscus repair needle usually adopts the "vertical mattress" suture method, with the suture perpendicular to the collagen fibers, providing the strongest tensile strength. To ensure a firm fixation, doctors often place 2-3 anchor nails, with the spacing controlled at around 5 millimeters. The scale markings on modern repair needles can help doctors precisely control the needle insertion depth, avoiding damaging the articular cartilage by penetrating the lower surface of the meniscus.

Anterior horn tear is relatively rare in clinical practice, but its treatment is not simple. The meniscus tissue in the anterior horn area is thin and has poor blood supply, with low healing potential. Additionally, the anterior horn is close to the infrapatellar fat pad and the patellar tendon, and it is prone to being interfered with by soft tissues during operation. The application of meniscus repair needles at this location requires extra caution: the insertion point should be as close to the meniscus edge as possible, and when the suture passes through, ensure that it includes a sufficient width of tissue (at least 3 millimeters); otherwise, the suture is prone to being cut. For radial tears in the anterior horn, some doctors will adopt the "full internal cross" technique, forming a grid-like fixation with two crossed repair needles to disperse stress.

Apart from the differences in the location, the shape of the tear also affects the choice of the repair needle. Longitudinal tears (the most common type being the bucket-handle-shaped tears) are suitable for vertical mattress suturing, where the repair needle needs to be inserted from one side of the tear, pass through the tear gap, and then exit from the other side. Horizontal tears are suitable for horizontal mattress suturing, where the repair needle is passed parallel to the meniscus surface, bringing the upper and lower lamellae together. For complex compound tears, multiple suture techniques may need to be combined, and the flexibility of the repair needle to change the thread is particularly important.

The blood supply condition is another crucial factor determining the repair strategy. The blood supply of the meniscus comes from the branches of the anterior and posterior arteries of the knee, covering only 10% to 30% of the lateral area (the red zone), while the central area (the white zone) has almost no blood supply. The healing rate of tears in the red zone can reach over 90%, while that in the white zone is less than 50%. Another innovative application of the meniscus repair needle is "biological enhanced repair": during suturing, the hollow channel of the repair needle is used to inject platelet-rich plasma (PRP) or bone marrow concentrate, providing growth factors to the non-blood-supplied areas and promoting healing. This dual function of "drug delivery + mechanical fixation" is becoming a new direction for the development of meniscus repair needles.

Finally, the post-operative rehabilitation plan must also be adjusted according to the location of the tear. After posterior horn repair, deep squats and extreme knee flexion (>90°) should be avoided to prevent excessive force on the sutures; after mid-part repair, rotational movements should be restricted, especially sudden stops and changes of direction; after anterior horn repair, excessive extension of the knee joint should be avoided. The strong fixation provided by the meniscus repair needles enables the implementation of these individualized rehabilitation plans, ultimately achieving the best functional recovery.