Description of a Dislocated Knee

A dislocated knee is an uncommon knee injury seen by orthopaedic physicians.

A knee dislocation typically happens after a traumatic fall, high-speed car injury or a severe sporting accident. Sometimes, a dislocated knee will go back (reduce) into place on its own or with assistance, but this is a very painful and complex process patients will often need to be put under anesthesia or be given a pain block to reduce the dislocated knee.

Dislocated knee symptoms include:

  • Physical deformity – crooked appearance
  • Severe pain
  • Numbness below the knee
  • Absent or diminished pulses in some cases

A dislocated knee is a very serious injury. It is very important that the vascular and nerve function status be determined at the time of injury. For more severe knee dislocations, a CT angiogram may be needed to determine if a potential popliteal artery injury exists. In addition, up to 35% of all dislocated knees also have nerve damage; this should be carefully evaluated at the time of injury, mainly for the common peroneal and tibial nerves.

Most dislocated knees involve injuries to three or four of the major knee ligaments. These include the ACL,PCL, posterolateral corner, and the medial knee structures (including the medial collateral ligament and posterior oblique ligament). In addition, there may be injuries to the medial or lateral meniscus, the articular cartilage, a fracture or patellar tendon injury. It is very important to carefully assess the injury both on history and physical exam – it is also important to obtain x-rays, an MRI scan, and other studies as necessary.

Dislocated Knee Treatment

It is well recognized that the outcomes of knee dislocation surgery are best in the hands of surgeons who perform them regularly and in large numbers. This is important due to the requirement of having a familiarity with injury patterns; a well versed surgical team, and a varied supply of allograft ligaments for reconstruction and other factors. Dr. LaPrade is able to offer all of these components to each patient that comes to him with a dislocated knee or any complex knee injury.

In general, the results of a dislocated knee are best if they are treated within the first 3-4 weeks of injury.

Confounding factors that can affect a dislocated knee include:

  • Popliteal artery bypass surgery
  • Blood clot
  • Significant amount of swelling
  • Knee stiffness
  • Abrasions or lacerations which may require a delay in surgery

Any associated lacerations or abrasions of the knee may also need to be carefully evaluated for the suitability of surgery to help minimize the risk of infection.

While there is some discussion as to whether the surgical treatment of a dislocated knee should be staged – the collateral ligaments are repaired/reconstructed first and then 6-8 weeks later the cruciate ligament reconstructions are performed – we strongly believe all of these injuries should be treated at once and in one surgery if possible.

Dr. LaPrade and his team are very experienced in knee dislocation surgery; the goal during surgery is to complete the surgery in an efficient and effective manner. Our usual recommended treatment for a dislocated knee is to reconstruct the ACL with a patellar tendon allograft, double bundle PCL reconstruction with an Achilles tendon and tibialis anterior allografts, repair with an augmentation of the medial knee structures or to perform a direct reconstruction of the medial knee structures, and to perform a concurrent hybrid repair and reconstruction of the posterolateral corner structures as needed. Our preference is to repair meniscal tears rather than to resect them when possible.


Research shows that 20-25% of patients need a second surgery to address stiffness, this can happen when the patient does not begin physical therapy exercises immediately after surgery. Dr. LaPrade strives to achieve a minimum of 0-90° range of motion on the first day of physical therapy after surgery to lower the risk of future surgery. This has proven to be successful in minimizing postoperative stiffens in our treated patients.

A dislocated knee is a very complex injury and, in general, there is no “cookbook” recipe to address them. Each patient has a unique injury pattern that must be assessed when making a surgical plan. However, a careful assessment, utilization of the physician’s knowledge and having the patient work with a well qualified physical therapist and rehabilitation protocol typically gets patients back to normal activities and, more often than not, to a high level of sporting activities.