Common Knee Injuries: Symptoms, Causes, and Treatment

Common Knee Injuries

Knee Plica

Fetal knee development involves three chambers that typically merge into one. The internal walls (plica) separating these chambers may persist. While often asymptomatic, the medio-patellar plica is most prone to causing issues. Symptoms can mimic meniscus injury, leading to catching and locking sensations.

Patellar Subluxation and Dislocation

Occurs at the patellofemoral joint, with lateral dislocations being the most common.

Knee Joint Dislocation

Occurs at the tibiofemoral joint and often involves tears of the MCL, ACL, LCL, and joint capsule.

Patellar Tendon Rupture

A complete tear of the quadriceps or patellar tendon, typically at its attachment to the patella.

Medial and Lateral Collateral Ligament Injuries

• Medial Collateral Ligament (MCL): Injuries are more common than LCL injuries.
• Lateral Collateral Ligament (LCL): Injuries often present with extracapsular swelling.

Posterior Cruciate Ligament (PCL) Sprain

Often caused by a dashboard injury or a posteriorly-directed force, such as a fall on a flexed knee with the foot plantarflexed. The PCL restrains posterior tibial motion.

Anterior Cruciate Ligament (ACL) Sprain

Considered the most serious ligament injury, frequently accompanied by medial meniscus and MCL injuries (Unhappy Triad). Patients often report feeling a "pop." Mechanism of injury involves excessive multi-planar joint motion and forces during jumping, cutting, and twisting, typically with low sagittal plane flexion and increased frontal and transverse plane motion (knee valgus). Risk factors include BMI, strength, anatomical factors (e.g., tibiofemoral angle, navicular drop), hormonal influences (potential effects on ligament compliance), and genetics.

Surgical Repair Options

• Autograft: Tissue harvested from the patient. Preferred over allograft, using either patellar tendon or hamstring tendon. Outcomes are similar between patellar tendon and hamstring tendon grafts.
• Allograft: Tissue harvested from a cadaver.

Meniscal Lesions

Partial or complete tears of the medial or lateral meniscus. Medial meniscus injuries are more common due to its limited mobility, being attached to the MCL and secured to the tibial plateau.

Unhappy Triad

A combination of ACL, MCL, and medial meniscus tears.

Osteochondral Defects

Damage where articular cartilage is sheared off the bone, referred to as an osteochondral fracture when bone is also involved.

Osteoarthritis

Inflammation of the joint caused by the "wear and tear" of articular cartilage. Symptoms include stiffness and swelling, with activity potentially causing flare-ups. Loose bodies may lead to catching, locking, and pain, along with weakness or buckling of the knee and crepitus (grinding).