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Knee News

Patellar Dislocation in Young, Active Adults

This is the first randomized controlled trial comparing two different treatment approaches for patellar (kneecap) dislocation. Forty patients with dislocation of the kneecap were included. All patients had a traumatic injury either from a military exercise or a sports activity. All of the patients were in the military. Most were men between the ages of 19 and 22.

The real question behind this study was: should a primary (first-time) patellar dislocation be treated right away with surgery? Or can it be managed nonoperatively with a knee orthosis (brace). What are the long-term results of both approaches? There are many surgical ways to stabilize a dislocated patella. In this study, two types of procedures were used based on the type of damage present. Besides a dislocated patella, patients also had an injury to the patellofemoral ligament requiring repair or reconstruction.

The mechanism of dislocation was a sudden displacement of the patella laterally (away from the other knee). The soft tissue structures along the medial side (closest to the other knee) were stretched and disrupted by the force of the pull. Bleeding and swelling into the area was common.

Before the study began, all patients had a knee aspiration done (usually within the first few days after injury). This means that fluid from the swelling was removed with a suction needle. Sometimes aspiration had to be done more than once, especially for patients with massive swelling. Anyone in the study with a loose bone fragment from fracture of the patella had it removed arthroscopically before being assigned to a treatment group.

Everyone was randomly placed in one of two groups: either surgery or bracing. Except for gender, the patient make-up of the two groups was very similar. Surgeons performing the operations could use any surgical technique they thought was best. No one was told to follow a specific surgical protocol. The brace group received a knee brace designed to hold the kneecap in place. This is called a patellar stabilizer.

Patients in both groups followed the same rehab program after their treatment, so that part of their management was the same. The only difference was one of timing: the surgical group began the exercise program 24 to 48 hours after surgery. The orthotic group began their exercise program right away. Exercises were prescribed and supervised by a physical therapist.

The rehab program started with isometric quadriceps exercises. The quadriceps is the large muscle along the front of the thigh. When it contracts, the patella is pulled upwards and the knee straightens. In isometric exercises, the muscle is contracted without actually moving the knee joint. Range-of-motion of the knee was limited to 30-degrees of flexion for the first three weeks. Patients were allowed to bend up to 90-degrees during weeks three through six. After six weeks, the brace could be taken off and the knee could move freely. At that point, a program of strengthening exercises was started.

A variety of different measures were used to compare the results between these two treatments. Patients answered questions and filled out surveys describing and rating their pain, function, activity level, and limitations. Functional activities included things like squatting, jumping, and climbing stairs. These activities are appropriate measures of outcome given that the patient population was a group of soldiers and many of them were involved in competitive athletics.

Knee range-of-motion was measured and size of the quadriceps muscle was compared from the injured side to the uninvolved side. X-rays and MRIs were also taken and compared before and after treatment. Severity of the injury was determined using MRIs. Grades I through IV are given based on how much of the cartilage and bone were damaged. Four areas of knee joint cartilage were assessed (two on each side of the joint).

The main outcome measure was whether the patella dislocated (partially or fully) and whether another operation was needed during the follow-up period. Patients were followed for an average of seven years. What they found was that there were far fewer redislocations in the follow-up period for the surgical group. Nearly one-third of the nonoperative (bracing and exercise) group had a second patellar dislocation. If partial dislocations called patellar subluxation are included, then almost half of the nonoperative group had patellar instability.

The authors concluded that early surgical stabilization and repair of the surrounding damaged soft tissue structures can reduce the risk of redislocation in young, active military recruits. Criteria for surgery used by these surgeons are a traumatic patellar dislocation with medial patellofemoral ligament injury. Type of surgery done depends on the type of injury, presence of fracture or bone fragments, and the natural contours of the patient's knees. Some patients may have imbalances in the shape and alignment of the patella that should be corrected at the time of surgery.


Petri J. Sillanpää, MD et. al. Treatment With and Without Initial Stabilizing Surgery for Primary Traumatic Patellar Dislocation. In Journal of Bone and Joint Surgery. February 2009. Vol. 91A. No. 2. Pp. 263-273.

02/19/2009

*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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