Evidence-Based Treatment For First-Time Patellar Dislocations
The current trend in medicine is to study each medical condition looking for evidence to support specific treatments as being the best way to approach a problem. One of the best ways to develop specific evidence-based treatment programs is to look back on patient outcomes after treatment and see what kind of results were obtained. Then a treatment algorithm (step-by-step process) can be developed.
In this article, a treatment algorithm for primary (first time) patellar (knee cap) dislocation is presented. The process begins with the physician taking a patient history and performing a physical exam.
The history includes questions about how, when, and why the injury happened. It's important to find out if the patient ever had a similar injury in the past (for either knee). A previous history of knee dislocation is a red flag for recurrent (repeated) patellar dislocations.
Clinical tests performed by the physician must confirm that a patellar dislocation occurred. Just as important, the examiner checks for any injuries or damage to other areas of the knee (e.g., ligaments, cartilage, connective tissue, bone).
In particular, knee dislocations with a piece of bone displaced may require a different treatment approach. This type of injury is referred to as an osteochondral fragment or fracture.
X-rays may not show evidence of bone damage. MRIs are more accurate in outlining the surface of the joint. Any disruptions that might suggest damage to the cartilage or bone with a free-floating fragment inside the patellar joint will be seen with MRIs.
The size and location of the fragment are important factors to evaluate when planning surgery. Small pieces or fragments may not have to be repaired or removed. Larger bone fragments may be reattached to restore and preserve the injured site.
The big question is always about treatment. Can primary patellar dislocations be managed conservatively (i.e., without surgery)? How do you know if surgery is needed? And what type of surgical procedure should be done? Looking back over studies done in this area, here's what the authors of this evidence-based review found:
Nonoperative care seems like a good idea but there are very few studies to support this conclusion or to identify what kind of program works best. Right now, surgeons are advised to put their patients with first-time patellar dislocations in an extension brace for six weeks. Physiotherapy to restore normal motion and strength is recommended. Patients who start putting weight and load on the joint after only three weeks of immobilization are much more likely to re-dislocate it later.
Swelling with blood in the joint requires MRIs to check for osteochondral fragments.
Large fragments can be surgically reattached but studies showing a long-term benefit for this treatment have not been done. It's possible that conservative care is just as effective as surgical repair but studies comparing these two treatment methods have not been done yet.
There simply isn't enough evidence that surgery should be done right away for every patient with a first-time patellar dislocation. Surgery should be considered more carefully after a second- or third-time (repeat) dislocation.
The natural history (what happens without treatment) is another area of more unknowns than knowns. There's no proof that surgery right away yields any better results than letting the area heal naturally.
It may seem like there's more we don't know than we do know about the best (evidence-based) treatment of first-time patellar dislocations. That's okay because it is a starting place from which to begin conducting studies. Finding out what we don't know points scientists in the right direction for developing specific research with practical outcomes.
The algorithm for evaluation and treatment of primary patellar dislocations has already been revised once based on new information. And it will likely be revised again in the future as further results are reviewed and reported.
For now, the algorithm provides a structured method for this condition. Conservative care is the main approach unless a fragment is displaced. And that piece of bone or cartilage must be large enough to have at least one or two pins put through it to reattach it to the main bone.
In light of the lack of research in this area, it looks like this is one area where future studies are needed.
Reference: Neel P. Jain, MD, et al. A Treatment Algorithm for Primary Patellar Dislocations. In Sports Health. March/April 2011. Vol. 3. No. 2. Pp. 170-174.