Cedera Meniskus Lutut

01Pathophysiology

The menisci are paired, C-shaped fibrocartilaginous structures located between the femoral condyles and the tibial plateau. The medial meniscus and the lateral meniscus serve as shock absorbers, load distributors, and secondary stabilizers of the knee joint. They also contribute to joint lubrication and proprioception. Without intact menisci, focal contact pressures across the articular cartilage increase dramatically, accelerating degenerative changes.

The medial meniscus is injured far more frequently than the lateral meniscus. This is because it is firmly anchored to the deep fibers of the medial collateral ligament (MCL) and the joint capsule, which makes it relatively immobile. During a twisting force on a flexed, weight-bearing knee, the medial meniscus cannot escape the shearing force between the femur and tibia, and it tears. In contrast, the lateral meniscus has looser capsular attachments and greater mobility, which allows it to accommodate rotational stress more effectively.

Understanding the vascular anatomy of the meniscus is essential because it determines both the healing potential and the management strategy. The meniscus receives its blood supply from the perimeniscal capillary plexus, which branches from the medial and lateral genicular arteries. This blood supply penetrates only the outer 10 to 30 percent of the meniscal width. Based on vascularity, the meniscus is divided into three zones:

• Red-red zone (outer third): Fully vascularized. Tears here have the best healing potential and are candidates for surgical repair.

• Red-white zone (middle third): Partially vascularized. Healing is variable and depends on tear pattern and patient factors.

• White-white zone (inner two-thirds): Avascular. Tears here do not heal on their own and typically require partial meniscectomy rather than repair.

The mechanism of acute meniscal injury involves a rotational force applied to the knee while it is in flexion and bearing weight. During sudden pivoting, the femur rotates on the fixed tibia, trapping and shearing the meniscus. This is why athletes in cutting and pivoting sports are disproportionately affected. In older adults, the collagen within the meniscus undergoes myxoid degeneration, making it prone to tearing from trivial or minimal trauma such as rising from a squatting position.

A displaced meniscal fragment, particularly a bucket-handle tear (a longitudinal tear in which the central fragment flips into the intercondylar notch), can physically block full knee extension. This is the pathophysiologic basis for the classic complaint of the knee "locking" in a flexed position.

02Classification and Clinical Manifestation

03Diagnostic Workup

The workup begins with a thorough history and physical examination. A patient who describes a twisting injury on a planted foot followed by knee pain, swelling that developed over several hours, and mechanical symptoms such as locking or catching should immediately raise suspicion for a meniscal tear. The delayed onset of effusion (developing 6 to 24 hours after injury) is a distinguishing feature, as opposed to the rapid hemarthrosis (within 1 to 2 hours) seen with ACL rupture.

On examination, joint line tenderness is the most sensitive finding but is not very discriminating on its own. The McMurray test is the most commonly tested maneuver and is performed with the patient supine. To test the medial meniscus, the examiner flexes the hip and knee maximally, applies a valgus stress with external rotation of the tibia, and then slowly extends the knee. A palpable click or pop along the medial joint line with pain constitutes a positive test. To test the lateral meniscus, the maneuver is repeated with internal rotation and varus stress. A common exam trap is confusing which rotation tests which meniscus: remember that external rotation tests the medial meniscus.

The Apley compression (grinding) test is performed with the patient prone and the knee flexed to 90 degrees. The examiner applies a downward axial load through the tibia while rotating the leg. Pain with compression favors meniscal pathology, whereas pain with distraction (Apley distraction test) suggests ligamentous injury.

Plain radiographs should be obtained as the initial imaging study, not because they will reveal the meniscal tear, but because they are essential for excluding fractures, loose bodies, and underlying osteoarthritis. The menisci are soft tissue structures and are not visible on X-ray.

MRI is the best non-invasive confirmatory test and is the imaging modality of choice when clinical suspicion is high. On MRI, a meniscal tear is identified by abnormal signal intensity within the meniscus that extends to at least one articular surface. MRI also provides valuable information about concomitant injuries (ACL, chondral lesions, bone bruises) and the tear pattern, which guides the surgical approach.

Arthroscopy remains the definitive diagnostic and therapeutic tool but is invasive. It is not ordered as a standalone diagnostic test. Arthroscopy is pursued when the clinical picture strongly supports a surgically significant tear, when MRI findings are equivocal, or when the patient has failed conservative management.

04Management and Treatment

Acute phase management follows the standard approach for soft tissue injuries. The patient should be instructed to rest the knee, apply ice for 15 to 20 minutes several times per day, use a compressive wrap, and elevate the limb. NSAIDs are the first-line pharmacologic agents for pain and inflammation control. If the patient has a contraindication to NSAIDs (renal insufficiency, active peptic ulcer disease, pregnancy in the third trimester), acetaminophen up to 3 grams per day can be used as an alternative analgesic, though it lacks anti-inflammatory properties.

The decision between conservative versus surgical management hinges on the tear location (vascular zone), tear pattern, patient age and activity level, and the presence of mechanical symptoms. Tears in the outer vascular zone in young patients are the best candidates for arthroscopic repair because the blood supply supports biological healing. In contrast, tears in the inner avascular zone will not heal and are managed with arthroscopic partial meniscectomy, where only the torn, unstable tissue is removed.

A bucket-handle tear causing a locked knee is treated as a relative surgical urgency. The displaced fragment blocks the normal gliding mechanics of the joint and prevents full extension. Surgical reduction of the fragment (with repair or meniscectomy) is the next best step.

Long-term management focuses on physical therapy emphasizing quadriceps and hamstring strengthening, proprioceptive training, and a gradual return to activity. After partial meniscectomy, patients can typically return to full activity in 4 to 6 weeks. After meniscal repair, return to sport is delayed to 3 to 6 months to protect the healing tissue.

An important point for exam purposes: in older patients with degenerative meniscal tears and coexisting osteoarthritis, arthroscopic surgery provides no additional benefit over structured physical therapy. This has been consistently demonstrated in randomized trials and is a commonly tested concept. The best management in this population is conservative.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students miss meniscal injury questions is by confusing the clinical presentation with an ACL tear. Both injuries share a similar mechanism (twisting on a planted foot during sports), but the timing of the effusion is the key separator. ACL tears produce immediate hemarthrosis that develops within the first 1 to 2 hours because of bleeding from the ruptured ligament. Meniscal tears produce a reactive, non-hemorrhagic effusion that develops gradually over 6 to 24 hours because the inner meniscus is avascular and does not bleed. If the vignette describes a swollen knee the morning after a game rather than immediately on the field, think meniscus.

Another frequent trap involves the McMurray test rotation. Students often reverse which direction tests which meniscus. The rule is: external rotation of the tibia with valgus stress tests the medial meniscus; internal rotation with varus stress tests the lateral meniscus.

The "unhappy triad" (also called the O'Donoghue triad) is a classic board concept involving simultaneous injury to the ACL, MCL, and medial meniscus. This occurs with a valgus force combined with external rotation, commonly seen in contact sports (e.g., a lateral blow to the knee). When a vignette describes all three structures injured together, the student must recognize that the meniscal component requires separate evaluation and management beyond the ligament injuries.

Be cautious with degenerative meniscal tears in elderly patients. A vignette presenting an older patient with chronic knee pain, a degenerative meniscal tear on MRI, and underlying osteoarthritis is testing whether you know that the correct answer is physical therapy, not arthroscopic surgery. Selecting surgery in this scenario is the intended wrong answer.

Finally, any vignette describing a patient who cannot fully extend the knee after a twisting injury ("the knee is locked") should immediately trigger consideration of a bucket-handle tear. This is a displaced longitudinal tear and is a relative surgical urgency. The next best step is arthroscopic intervention, not conservative management with physical therapy.