Case Study: Chronic Knee Dislocations Due to Work Injury

A 31 year old male patient came into the office complaining of continuous knee pain. He also complained that his kneecap would “give out”. During the examination, we determined the problems began back in 2008 following a work injury. The patient explained that during the incident, he had twisted his knee at work, which had caused his knee to dislocate.

At the time, the patient had been treated with physical therapy and a brace. He was able to return to work following the injury but continued to suffer with the symptoms described above for years. Upon examination, it was determined that he was suffering from chronic patella instability and multiple dislocations.

As part of the examination, we noted the following:

•           Knee swelling

•           Increased patella laxity

•           Positive patellar apprehension sign

•           Increased Q angle

Before determining the exact treatment protocol, the increased Q angle indicated the need to perform a CT scan to measure the distance between the tibial tubercle and the trochlear groove. This is referred to as the T-T distance. A T-T distance greater than 2.0 cm requires the anteromedial transfer of the tibial tubercle and will decrease the T-T distance. This will encourage improved stability of patella.

It was determined that the best treatment approach was to combine two surgical procedures at the same time. The first procedure is referred to as MPFL reconstruction. The medial patellofemoral ligament or MPFL is a thin band of tissue that attaches the kneecap to the inner part of the knee. When the kneecap dislocates, it often tears the MPLF on the inside of the knee, which is important for stability in the knee. During the procedure, the MPFL is reconstructed and re-attached in the most anatomically correct position. To do this, we used a hamstring allograft and replaced the torn MPFL.

The second procedure is referred to as anterio-medialization of the tibal tubercle. The operation focuses on recentering the patella and reduces patellofemoral contact pressure. This improves the Q angle and reduces lateral vector force on the reconstructed MPFL.

The surgery proved to be a success. Following surgery, the patient was in a hinged brace and utilized crutches for 4 weeks. He then completed 12 weeks of physical therapy that was focused on edema control, range of motion and strength training. He was able to return to his job as a laborer 3 months post-op. He is currently doing extremely well and no longer suffers from patellar instability. He currently works 50-60+ hours per week without difficulty. 

Lateral Patellar Instability and the Medial Patellofemoral Ligament (MPFL)

Lateral patellar instability occurs when the kneecap dislocates out of place. The kneecap or patella is a small bone in the front of the knee. It glides along the femoral groove (a groove in the femur bone) as the knee bends and straightens. If the patella comes out of the groove completely, it is referred to as patellar dislocation. If the patella comes out of the groove partially, it is referred to as patellar subluxation.

Symptoms of dislocations of the kneecap are as follows:

-          Pain at the knee joint
-          Swelling
-          Obvious displacement of the kneecap (kneecap can often briefly dislocate and return, but pain and swelling will still be present)

When the kneecap dislocates, it often tears the medial patellofemoral ligament on the inside of the knee. The MPFL is a thin band of tissue that attaches the kneecap to the inner part of the knee. The medial patellofemoral ligament or MPFL is important for stability in the knee.

There are surgical and non-surgical treatments for patellar instability. Rest, ice and bracing have been known to heal the injury and prevent recurrent dislocations. However, surgical intervention is sometimes needed to correct recurrent dislocations.

If the MPFL is torn, the patient can potentially benefit from a surgical procedure known as MPFL reconstruction. Reconstruction of the MPFL is a surgical procedure that restores patellofemoral stability. The most successful and widely accepted approach to this procedure is to use an approach that restores the MPFL to its anatomically correct position. This procedure, along with other options, such as tibial tubercle osteotomy, and/or a trochleoplasty can be used to correct the problem. The exact treatment protocol varies by individual.