What is a knee dislocation?
When the thigh bone of the knee (Femur) separates from the leg bone (Tibia) following an injury to the knee, it is termed as a knee dislocation
How serious is this kind of injury?
A great deal of force is necessary for the two bones of the knee to separate from each other to result in a dislocation.
This injury is common in vehicular accidents, contact sports and sports involving speed. However in heavy individuals large forces acting across the knee, even due to trivial falls can result in a knee dislocation.
During a knee dislocation, multiple ligaments holding the knee together get injured and torn. Depending on the severity of dislocation, the nerves and vessels around the knee may also get injured. A dislocation may also be associated with fractures around the knee or other bone injuries. This is therefore a grievous injury which needs to be taken very seriously and treated appropriately with precision and care.
Which structures of the knee get injured following a dislocation?
Depending on the type of dislocation various structures may get injured in differing combinations and severity. This includes a combination of ligaments, cartilage, meniscus, joint capsule, bone, nerves and vessels.
Ligaments : ACL, PCL, Poserolateral (PLC), Posteromedial(PMC), Anterolateral(ALC) & Anteromedial(AMC) ligament complex, Patellar tendon, Quadriceps apparatus
Cartilage : Cartilage of Femur, Tibia or Patella
Meniscus : Medial or Lateral meniscus
Joint capsule : Posteromedial or Posterolateral capsule
Bone : Fractures and bone contusions
Nerves : Common peroneal, Tibial nerves
Vessels : Popliteal & Tibial vessels
How do I recognize a knee dislocation following an injury?
The knee appears swollen with bruising around the joint. It is difficult to sustain balance on the injured knee and one may not be able to walk without support. Very often the knee buckles on the very first attempt to stand up following the injury.
If there is a feeling of tingling, numbness or altered sensations below the knee, it could indicate a nerve injury. A discoloration in the leg and excessive swelling around the feet could also indicate injury to blood vessels around the knee. These are emergency situations requiring urgent critical specialized care.
What happens if the dislocation is neglected or treated incorrectly?
Knee dislocation is a grievous form of injury requiring specialized treatment. Inadequate treatment can lead to loss of knee movements, joint stiffness, recurrent swelling, persistent pain or instability of the joint. Severe injuries involving the nerves and vessels need immediate attention or else it may even result in loss of limb.
If left neglected over a prolonged period, it invariably results in persistent instability with early degeneration, wearing out of the joint and irreversible arthrosis.
How is it different from other knee ligament injuries?
Isolated ligament injuries commonly involving the ACL (Anterior Cruciate Ligament) or the PCL (Posterior Cruciate Ligament) may not be as grievous as a knee dislocation. The management of these isolated ligament injuries may require surgical expertise which are commonly followed by surgeons specialized in this field.
Knee dislocations have multiple- ligament injuries with a complex structural involvement. These require expert assessment to recognize the precise nature and extent of injury. Accordingly the correct modality of treatment needs to be planned for assuring best possible results. Expertized surgical execution is necessary which is mostly a combination of arthroscopic, mini-open and/or open surgical procedures. This requires the surgeon to have the necessary know how and surgical skills to perform all the combination of procedures.
What should be the immediate care ?
Immediate relocation of a dislocated knee is essential followed by correct positioning, resting, icing, compression dressing and keeping the limb elevated.
The condition requires medical attention as an emergency. If relocation of the knee is not achievable, an emergency surgery may also be required in certain cases. Cases with nerve or vessel involvement need close monitoring and may require emergency surgery.
What investigations are necessary?
Plain X-rays of the knee are more often deceptively normal in this condition.
MRI is an essential investigation
Angiography may be required in some cases where vascular injury is suspected
EMG–NC may be required for assessing nerve damage
Is plastering the knee a good method of treatment ?
Plastering the knee often leads to stiffness in the knee and improper healing of tissues. Most often it is an inadequate modality of treatment for a knee dislocation giving substandard results. It may be opted for in very rare selective cases.
What are the other possible treatment options ?
Depending on the severity and extent of injury, most commonly a knee dislocation would require a surgical modality of treatment. This is in order to get it back to normal functionality.
The surgical treatment is often a combination of arthroscopic and open/mini-open procedures.
What is the difference between ligament repairs & reconstructions?
When the torn or damaged tissues are restored back to their previous condition by suturing or anchoring them to their original location, they are termed as repairs.
When another tissue is used to recreate/rebuild a damage structure within the joint, it is termed as a reconstruction
What is the recovery period and prognosis?
Knee dislocations occur in a wide range of severity and type of dislocation. The management of these therefore varies considerably.
The treatment of each case is customized depending on the various findings following a detailed assessment. The recovery period could therefore vary from 3months to a year or even more.
Can I resume to sports following the treatment?
The aim of Joint Preservation Surgery is to get the joint back to its full normal function without any residual symptoms.
Few knee dislocations with extensive injury patterns may not be able to resume sports due to the nature of injury. However a majority would be able to resume pre-injury level of sports following correct treatment.