What is a Complex Knee Injury?
The knee has four main ligaments that stabilize the knee: Medial Collateral Ligament (MCL), Lateral Collateral Ligament (LCL), Anterior Cruciate Ligament (ACL), and Posterior Cruciate Ligament (PCL). These ligaments work together to allow normal knee range of motion while also providing knee joint stability. A complex knee injury involves damage to three or more of these main stabilizing knee ligaments. This injury is common when a knee dislocation occurs. Dr. Cunningham is a knee specialist at Vail Summit Orthopaedics and Neurosurgery. He is an expert at diagnosing and treating complex knee injuries for patients in Vail, Summit County, Aspen, and Denver, CO.
How Does a Complex Knee Injury Occur?
A complex knee injury occurs due to a traumatic incident. This often involves a high-speed motor vehicle accident, severe athletic injury, or a bad twisting fall. The high energy injury can dislocate the knee, in which the bottom of the thigh bone (femur) which normally creates a hinge joint with the top of the shin bone (tibia) disengages. The two bones can suffer a partial or complete separation from one another.
The mechanics of a knee dislocation typically occurs when the knee is bent slightly and a force causes the lower leg to rotate outward. In a knee dislocation, the ACL and/or PCL tear. In addition, the MCL and/or LCL also tear. are injured. A knee dislocation is an orthopedic emergency, that requires immediate medical attention.
What Happens When the Knee Dislocates?
When the femur and tibia are forcefully unhinged from one another, the tibia can shift anteriorly, posteriorly, medially, or laterally. Symptoms of a dislocated knee include:
- Popping sounds upon injury
- Severe and increasing pain
- Obvious deformity of the knee
- Inability to bear weight on the knee
- Very limited motion of the knee
- Immediate instability of the knee
- Swelling
- Bruising
- Numbness below the knee but usually with the ability to wiggle toes
Due to the serious nature of a knee dislocation, immediate medical attention is necessary. It is critical to get a comprehensive evaluation to prevent further damage, particularly as blood vessel and nerves may be kinked and damaged, compounding the potential for damage.
How to Diagnose a Dislocated Knee
The diagnosis of a dislocated knee begins with an urgent orthopedic evaluation. There is often an obvious deformity that points to the diagnosis of a knee dislocation. Time is of the essence to make the diagnosis and get the knee joint realigned. After obtaining a quick history, the condition of the skin evaluated. Nerve function is checked by seeing if one can move the ankle and toes up and down. Vascularity is assessed by feeling for pulses in the arteries of the foot.
Xrays will be ordered urgently. If the knee is dislocated on an xray, the patient is sedated in the emergency room and the knee joint is gently manipulated to put the hinge joint back in place. After realigning the knee, the knee ligaments are gently tested to see which ligaments are torn while the patient is sedated. Because a dislocated knee with multiply torn ligaments are grossly unstable, the knee is placed in a large knee brace. After the knee has been realigned, a CT arthrogram may be ordered to assess the blood vessels in the leg for occlusions or injury. A non-emergent Magnetic Resonance Imaging (MRI) of the knee will be obtained. The MRI will show which ligaments are torn as well as show meniscus tears or other cartilage damage that may have occurred. With these diagnostic studies having been performed, the best treatment plan can be determined.
Does a Dislocated Knee Injury Require Surgery?
In most cases, ligament, tendon, bone, vascular or nerve damage requires surgical repair, usually within 1 – 3 weeks after the initial swelling is reduced. Use of a leg brace or splint and post injury home care will be prescribed during this period. Resting the leg, managing pain, icing and elevating the leg are some of the home treatments. The surgical procedure will be either arthroscopic or open surgery in cases with a greater degree of damage. The goal of the surgery is to reconstruct each ligament within the knee to help restore normal function.
What is the Recovery Like After a Complex Knee Injury?
Recovery from a dislocated knee is dependent on many factors, including:
- The cause of the injury and degree of damage
- Damage to nerves and blood vessels
- The course of treatment
- Patient compliance with treatment and rehabilitation plan
Due to the complexity of this type of knee injury, rehabilitation can take between 9 – 12 months. Following a comprehensive treatment and rehabilitation program patients can return to normal daily activities. Dr. Cunningham is a knee specialist at Vail Summit Orthopedics. He is an expert at diagnosing and treating dislocated knee injuries for patients in Vail, Aspen, and Denver, CO.