A tibiofemoral knee dislocation, where the thigh bone (femur) separates completely from the shin bone (tibia), is a severe orthopedic injury and a true medical emergency. This is distinct from the more common, less severe kneecap (patellar) dislocation. The sheer force required to displace the main knee joint puts surrounding structures, including nerves and major blood vessels, at high risk of injury. Because of the potential for devastating complications, immediate professional medical attention, such as calling 911 or emergency services, is necessary.
Recognizing a Severe Knee Injury
The most immediate sign of a tibiofemoral dislocation is intense pain and a visible, unnatural deformity of the knee joint. The joint may appear grossly out of place, or the leg may be positioned at an abnormal angle. This trauma makes it impossible to bear weight on the injured leg, and the person cannot move or straighten the joint.
The mechanism of injury typically involves high-impact trauma, such as motor vehicle accidents or high-velocity sports injuries. The primary concern is not the bones themselves, but the potential damage to the popliteal artery, a major blood vessel running behind the knee. Injury to this artery can lead to a reduced blood supply to the lower leg, which may present as numbness or a cool feeling in the foot.
Immediate Actions While Waiting for Help
The most important instruction for anyone assisting an injured person is to never attempt to move, straighten, or manually “reset” the dislocated joint. Forcing the joint back into place can cause further damage to already compromised ligaments, nerves, or blood vessels. The limb must be treated with caution in the position in which it was found.
Safe stabilization can be achieved using soft materials, like pillows, rolled blankets, or clothing, to gently support the limb in its current alignment. These materials serve as an improvised splint to minimize movement while waiting for paramedics. Applying a cold pack wrapped in a cloth can help manage pain and reduce swelling around the joint.
Checking the circulation in the foot is an important step to monitor the limb’s blood supply. This can be done by checking for a pulse in the foot or by observing the capillary refill—pressing briefly on a toenail and noting how quickly the pink color returns. Any change in sensation, such as increasing numbness, or a loss of pulse should be immediately reported to emergency medical personnel.
Urgent Hospital Treatment and Stabilization
A knee dislocation is a limb-threatening emergency, and the immediate focus of hospital treatment is to restore blood flow and realign the joint. The urgency stems from the high risk of popliteal artery damage, which occurs in 20 to 40 percent of knee dislocations and can lead to amputation if not addressed quickly. Ischemia, or a lack of blood flow, lasting more than eight hours is associated with amputation rates exceeding 80 percent.
The initial procedure is a closed reduction, where a doctor manually guides the bones back into alignment, typically performed under sedation in the emergency department. If the limb shows signs of poor circulation, such as an absent pulse, this reduction must be performed immediately, sometimes before X-rays are taken. Following reduction, the limb’s vascular status is assessed, often using an Ankle-Brachial Index (ABI) test, which compares blood pressure in the ankle to the arm.
If the ABI is low, or if a strong pulse remains absent after reduction, a CT angiography or immediate surgical exploration is necessary to identify and repair the damaged popliteal artery. This vascular repair takes precedence over all other orthopedic injuries. If the joint cannot be reduced manually, an open reduction (a surgical procedure) is required. The knee is then often immobilized in a brace or a spanning external fixator, which temporarily stabilizes the joint by connecting pins in the femur and tibia with an external frame.
Post-Reduction Recovery and Rehabilitation
Once the joint is stabilized and any vascular damage is addressed, the long-term process of recovery begins. A knee dislocation almost always results in significant damage to the major stabilizing ligaments, such as the anterior and posterior cruciate ligaments (ACL and PCL). This multiligamentous injury often necessitates complex reconstructive surgery, which may be delayed until swelling subsides and the soft tissues improve.
Physical therapy (PT) is the fundamental component of rehabilitation, starting with early, controlled exercises to prevent joint stiffness, a common complication known as arthrofibrosis. The initial goals of PT focus on restoring the range of motion and achieving full knee extension. Strengthening exercises targeting the quadriceps, hamstrings, and hip muscles are progressively introduced to improve joint stability and function.
The timeline for a full recovery is lengthy, typically ranging from six months to over a year, depending on the number of ligaments injured and the need for subsequent surgical reconstructions. Patients rely on crutches and specialized braces for an extended period, and adherence to the structured PT regimen is crucial for achieving a return to pre-injury activity levels.