Copyright © 2008 by The Journal of Bone and Joint Surgery, Inc.

Commentary & Perspective

Commentary & Perspective on
"Acute Patellar Dislocation in Children and Adolescents: A Randomized Clinical Trial"
by Sauli Palmu, BM, et al.

Commentary & Perspective by
William E. Garrett Jr., MD, PhD, and Kevin L. Krasinski, MD*,
Duke University Medical Center, Durham, North Carolina

Posted March 2008

Palmu and coauthors have evaluated operative and nonoperative treatment of acute patellar dislocation in children in a prospective, randomized trial with a follow-up of fourteen years. The generally satisfactory outcome of this evidence-based study, despite a high risk of recurrent dislocation, is welcome news.

The study demonstrates a similar conclusion to that of our study, published in 1996, which showed that, in a case series of patients, early surgical treatment (acute surgical repair of the medial patellofemoral ligament) did not significantly improve the outcome in comparison with previously reported results of nonoperative treatment1.

At that time, we repaired medial patellofemoral ligaments that had been torn from the femur. Our study was primarily a pathoanatomic study. We were unaware at that time that any similar study existed in the English-language literature. Contemporary literature emphasizes repair or reconstruction of this ligament2, which is the primary stabilizer to prevent lateral dislocation3.

At the time that the Palmu study was performed, there was far less awareness of the importance of the medial patellofemoral ligament and the pathoanatomy of patellar dislocations. The issue of whether or not to perform surgery for acute dislocations of the patella is similar to the issue of whether or not to treat with medicine. What is most important is the kind of medicine or surgery that is chosen. The medicine must be clearly chosen to fit the conditions. In the study by Palmu et al., the surgical technique chosen by the authors must be questioned with respect to current surgical concepts. Fewer than half of the patients in their study had repair of the medial patellofemoral ligament. Thus, acute repair of the medial patellofemoral ligament was not the standard of care in this series and the surgical technique used by the authors is different than it might be currently4. The authors do not mention whether the medial patellofemoral ligament was repaired to its femoral attachment. The authors also point out that lateral release alone was performed in 19% of the operatively treated knees, which is also not the current practice.

The surgery as performed by the author apparently did not affect the outcome. Still, eleven (39%) of twenty-eight nonoperatively treated knees and sixteen (44%) of thirty-six operatively treated knees required subsequent surgery. It is not clear how many of the ultimate outcomes were influenced by subsequent surgery. We do not know the nature of the subsequent surgery. Although most patients were doing well at the time of long-term follow-up, 40% did not have a good or excellent result and 42% required additional surgery. Initial treatment for patella dislocation clearly has room for improvement. This paper does not rule out the possibility that specific risk factors might help to identify patients who are less likely to do well and that improved surgical procedures might be successfully used in the patients at higher risk.

*The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

References

1. Sallay PI, Poggi J, Speer KP, Garrett WE. Acute dislocation of the patella: a correlative pathoanatomic study. Am J Sports Med. 1996;24:52-60.
2. Smith TO, Walker J, Russell N. Outcomes of medial patellofemoral ligament reconstruction for patellar instability: a systemic review. Knee Surg Sports Traumatol Arthrosc. 2007;15:1301-14.
3. Conlan T, Garth WP Jr, Lemons JE. Evaluation of the medial soft-tissue restraints of the extensor mechanism of the knee. J Bone Joint Surg Am. 1993;75:682-93.
4. Bicos J, Fulkerson JP, Amis A. Current concepts review: the medial patellofemoral ligament. Am J Sports Med. 2007;35:484-92.