Dislocated Knee: Causes, Symptoms, Treatment, and Rehabilitation

What is a dislocated knee in the right leg?

A dislocated knee, also known as a tibiofemoral dislocation, is a severe and uncommon injury where the bones forming the knee joint (the tibia and femur) are completely separated from their normal alignment. This condition in the right leg signifies a significant traumatic event requiring immediate medical intervention due to the high risk of associated neurovascular damage.

Understanding Knee Anatomy

To comprehend a knee dislocation, it's essential to first understand the complex anatomy of the knee joint. The knee is a hinge joint, primarily formed by the articulation of three bones:

• Femur: The thigh bone.
• Tibia: The larger of the two lower leg bones, or shin bone.
• Patella: The kneecap, which glides over the front of the femur.

Stability in the knee is provided by a robust network of ligaments, which are strong, fibrous tissues connecting bones:

• Cruciate Ligaments:
  • Anterior Cruciate Ligament (ACL): Prevents the tibia from sliding too far forward relative to the femur.
  • Posterior Cruciate Ligament (PCL): Prevents the tibia from sliding too far backward relative to the femur.
• Collateral Ligaments:
  • Medial Collateral Ligament (MCL): Provides stability to the inner side of the knee.
  • Lateral Collateral Ligament (LCL): Provides stability to the outer side of the knee.

These ligaments, along with the joint capsule and surrounding musculature (quadriceps and hamstrings), work synergistically to allow smooth movement while preventing excessive motion and maintaining joint integrity.

What is a Knee Dislocation?

A knee dislocation occurs when the main articulating surfaces of the tibia and femur lose complete contact. Unlike a patellar dislocation (where only the kneecap moves out of place), a tibiofemoral dislocation is a much more serious injury that typically involves the rupture of multiple major knee ligaments, often including both cruciate ligaments and at least one collateral ligament. The severity stems not only from the extensive damage to the joint itself but also from the high incidence of injury to critical neurovascular structures that pass behind the knee, such as the popliteal artery and peroneal nerve.

Types of Knee Dislocations

Knee dislocations are typically classified by the direction of the tibia's displacement relative to the femur:

• Anterior Dislocation: The most common type, where the tibia moves forward relative to the femur. Often caused by hyperextension of the knee.
• Posterior Dislocation: The tibia moves backward relative to the femur. Often caused by a direct blow to the front of the tibia while the knee is flexed (e.g., a "dashboard injury" in a car accident).
• Medial Dislocation: The tibia moves inward (medially) relative to the femur.
• Lateral Dislocation: The tibia moves outward (laterally) relative to the femur.
• Rotatory Dislocation: A combination of displacement and rotation.

These classifications help medical professionals understand the mechanism of injury and anticipate potential associated damage.

Causes and Mechanisms of Injury

Knee dislocations are almost always the result of high-energy trauma. The force required to disrupt the strong ligamentous structures of the knee is substantial. Common scenarios include:

• Motor Vehicle Accidents (MVAs): Particularly head-on collisions where the knee strikes the dashboard (posterior dislocation) or forces the knee into hyperextension.
• Falls from Significant Heights: Landing directly on the knee or with an outstretched leg.
• High-Impact Sports Injuries: Such as those seen in football, rugby, or skiing, where there are direct blows to the knee or extreme twisting/hyperextension forces.
• Industrial Accidents: Involving heavy machinery or crushing injuries.

Less commonly, a knee dislocation can occur with low-energy trauma in individuals with extreme joint laxity or specific underlying conditions.

Signs and Symptoms

A dislocated knee in the right leg presents with unmistakable and severe signs and symptoms:

• Obvious Deformity: The most striking sign is a visibly deformed or unnatural appearance of the knee joint. The lower leg may be angled abnormally.
• Severe Pain: Intense and immediate pain at the time of injury.
• Inability to Bear Weight: The individual will be unable to put any weight on the affected right leg.
• Rapid Swelling: Due to internal bleeding and fluid accumulation within the joint.
• Joint Instability: A feeling that the knee is completely unstable or "out of place."
• Loss of Pulse in the Foot (Distal Ischemia): This is a critical sign of popliteal artery injury. The foot on the affected side may feel cold, appear pale or bluish, and have diminished or absent pulses. This is a medical emergency.
• Numbness or Tingling (Paresthesia): Indicative of nerve damage, particularly to the peroneal nerve, which can lead to foot drop (inability to lift the front part of the foot).
• Bruising: May develop over time around the knee.

Immediate First Aid and Medical Attention

A dislocated knee is an orthopedic emergency. Immediate action is crucial to minimize complications, especially neurovascular damage.

• Do NOT Attempt to Reduce the Dislocation: Never try to push the bones back into place yourself. This can cause further damage to nerves, blood vessels, and soft tissues.
• Immobilize the Leg: If possible, keep the right leg as still as possible in the position it was found.
• Call Emergency Services (911/112/999): Seek immediate professional medical help.
• Check for Circulation and Sensation: If trained, quickly assess the pulse in the foot and check for sensation and movement in the toes. Report any abnormalities to emergency responders.
• Elevate (if possible): Gently elevate the injured leg if it does not cause more pain or instability.
• Control Bleeding (if open wound): Apply direct pressure to any open wounds with a clean cloth.

Diagnosis

Diagnosis of a knee dislocation is typically made rapidly based on the obvious clinical presentation. Further diagnostic tests are then performed to assess the extent of the damage and identify any associated injuries:

• Clinical Examination: A thorough assessment of the knee, including palpation, evaluation of deformity, and careful neurovascular checks (pulses, sensation, motor function).
• X-rays: To confirm the dislocation, identify any fractures, and assess the direction of displacement.
• CT Angiography (CTA) or Angiography: This is often performed urgently to assess the popliteal artery for injury, as vascular damage is a limb-threatening complication.
• Magnetic Resonance Imaging (MRI): Once the knee is reduced and stabilized, an MRI is crucial to evaluate the extent of ligamentous, meniscal, and cartilaginous damage. This helps in surgical planning.

Treatment Options

Treatment for a dislocated knee is a multi-stage process, beginning with emergency intervention and progressing through surgical repair and extensive rehabilitation.

• Emergency Reduction: The immediate priority is to realign the bones of the knee joint. This is typically performed by a medical professional in an emergency setting under sedation or anesthesia. Prompt reduction can relieve pressure on blood vessels and nerves.
• Vascular Repair: If a popliteal artery injury is identified, emergency vascular surgery is performed to repair the damaged artery and restore blood flow to the lower leg. This is a limb-saving procedure.
• Nerve Repair: While some nerve injuries may recover spontaneously, severe damage to nerves (like the peroneal nerve) may require surgical exploration and repair, though outcomes can vary.
• Ligament Reconstruction/Repair: After the initial emergency, surgical repair or reconstruction of the torn ligaments (ACL, PCL, MCL, LCL) is almost always necessary. This is often performed in a delayed fashion once swelling has subsided and other immediate threats are managed. The specific ligaments repaired or reconstructed depend on the pattern of injury.

Rehabilitation and Recovery

Rehabilitation following a knee dislocation is a long and challenging process, often lasting 6-12 months or more, depending on the severity of the injury and the extent of surgical repair. It is crucial for restoring function and preventing long-term complications.

• Initial Immobilization: The knee is typically immobilized in a brace for a period to protect the healing structures.
• Range of Motion (ROM) Exercises: Gradual progression to restore knee flexion and extension, often with the guidance of a physical therapist.
• Strengthening Exercises: Targeting the quadriceps, hamstrings, glutes, and calf muscles to restore muscle strength and support the knee joint.
• Proprioception and Balance Training: Exercises to re-educate the body's sense of joint position and improve balance.
• Gait Training: Learning to walk properly without limping and progressing to normal walking patterns.
• Sport-Specific Training: For athletes, this involves progressive drills to prepare for a safe return to sport, emphasizing agility, cutting, and jumping.

Adherence to a structured physical therapy program is paramount for optimal recovery.

Potential Complications

Despite immediate and appropriate medical care, a dislocated knee carries several potential complications:

• Vascular Injury: Damage to the popliteal artery is the most serious complication, potentially leading to compartment syndrome, limb ischemia, and even amputation if not promptly managed.
• Nerve Injury: Damage to the peroneal nerve (leading to foot drop) or tibial nerve, which can result in persistent numbness, weakness, or motor deficits.
• Chronic Instability: Even after surgical repair, some degree of instability may persist.
• Stiffness and Arthrofibrosis: Excessive scar tissue formation within the joint can severely limit range of motion.
• Osteoarthritis: The extensive damage to the joint cartilage and supporting structures increases the long-term risk of developing degenerative arthritis.
• Infection: A risk with any open wound or surgical procedure.
• Compartment Syndrome: A dangerous condition where swelling within the muscle compartments of the lower leg causes dangerous pressure buildup, potentially leading to muscle and nerve damage.

Prevention Strategies

While not all high-energy trauma can be prevented, certain measures can reduce the risk of knee dislocations:

• Safe Driving Practices: Adhering to speed limits, wearing seatbelts, and avoiding distracted driving significantly reduces the risk of motor vehicle accidents.
• Workplace Safety: Following safety protocols and using appropriate protective equipment in industrial settings.
• Sports Safety:
  • Proper Technique: Learning and utilizing correct biomechanics for movements in sports.
  • Strength and Conditioning: Maintaining strong quadriceps, hamstrings, and core muscles to provide dynamic stability to the knee.
  • Proprioceptive Training: Exercises that improve balance and joint awareness.
  • Appropriate Protective Gear: While not foolproof, some protective gear may offer a degree of protection in high-impact sports.
• Awareness of Environment: Being mindful of surroundings to prevent falls from heights or other traumatic events.

Conclusion

A dislocated knee in the right leg is a severe orthopedic injury that demands immediate and comprehensive medical attention. Its complexity lies not only in the extensive damage to the knee joint's ligamentous structures but also in the high risk of associated neurovascular compromise, particularly to the popliteal artery. Understanding the anatomy, mechanisms of injury, and critical signs is vital. For fitness enthusiasts, personal trainers, and student kinesiologists, recognizing the gravity of this injury underscores the importance of proper training techniques, injury prevention strategies, and the absolute necessity of prompt professional medical intervention should such a traumatic event occur. The path to recovery is arduous, requiring dedicated rehabilitation to restore function and mitigate long-term complications.