August 2016

Surgery beats conservative care for first-time kneecap dislocations

8peds-news-patellar-shutterstock_280947350_SM-copyLess recurrence, better sports outcomes

By Greg Gargiulo

Adolescent patients with first-time acute patellar dislocations treated surgically have a lower risk for recurrent dislocation and higher knee-related quality of life and sports-related outcomes compared with those managed conservatively, according to a recent  review and meta-analysis from the Hospital for Special Surgery (HSS) in New York City.

“Our review was focused on first-time patella dislocators, which is a more controversial area than recurrent or chronic cases,” said first author Benedict Nwa­chukwu, MD, an orthopedic surgery resident at HSS. “We believe our findings suggest surgery may be able to better restore patients to preinjury level of function than conservative care.”

Nwachukwu and colleagues included 11 studies that provided data on 627 injured knees: 470 were managed conservatively (mean age of patients, 17 years) and 157 were treated surgically (mean age, 16.1 years). The overall quality of the studies analyzed was variable, with only two using a randomized controlled trial design.

Of the conservatively managed knees, 136 (30.9%) sustained a repeat dislocation, while 35 (22.3%) of those treated surgically experienced another dislocation. Both conservative and surgical treatments were associated with good functional outcomes. Surgery, however, was associated with significantly higher Knee Osteoarthritis Outcomes Scores (KOOS) for knee-related quality of life, daily function, and sports and recreation compared with conservative care. The most commonly used surgical procedure is medial patellofemoral ligament reconstruction.

Knee Surgery, Sports Traumatology, Arthroscopy published the findings in March 2016.

The standard of care for patellar dislocation is conservative management, based on historical studies, such as Cash and Hughston in 1988 in the American Journal of Sports Medicine, that have found good, if not excellent, results with nonoperative care, said Nwachukwu. This care consists almost exclusively of physical therapy to improve proprioception and strengthen the quadriceps and surrounding knee musculature.

Trochlear dysplasia and skeletal immaturity were risk factors for repeat dislocation in both groups.

“The current controversy is mainly among surgeons, to whom these patients present,” Nwachukwu said. “Surgery is associated with a decreased risk of recurrent dislocation, but, because it’s an invasive procedure, it can be challenging to decide when it is most appropriate.”

In addition to the primary outcomes, the current study also identified trochlear dysplasia and skeletal immaturity as predictive risk factors for repeat dislocation in both conservatively and surgically treated patients. Although little attention is currently paid to these characteristics, the results encourage more consideration of them when making treatment decisions, experts say.

“The decision of whether to undergo surgical or conservative treatment with initial patellar dislocation should be made after careful discussion with the child, parents, and surgeon,” Nwachukwu said. “With the understanding that surgery was shown in our study—as well as in institutional experience—to decrease the risk of recurrent dislocation, we hypothesize that surgery attenuates the risk of recurrent dislocation in children with pathoanatomic findings of immature physes and trochlear dysplasia.”

Because patients who underwent surgery also demonstrated higher functional outcome scores on the KOOS sports-related outcomes subscale, an additional consideration for undergoing early surgery might include an elite level of athletic participation, he said.

These findings therefore suggest that, in highly active pediatric patients with pathoanatomy that predisposes them to recurrent dislocation, surgery as a first-line treatment might reduce recurrence risk and maximize functional outcome.

However, the quality of featured studies urges caution.

“This is a well-performed meta-analysis, but it is limited by the quality of the data in the included studies,” said Laurel Blakemore, MD, associate professor and chief of the Division of Pediatric Ortho­paedics at the University of Florida College of Medicine in Gainesville. “The study does suggest there may be an indication to consider earlier surgical treatment in the highly active pediatric athlete based on measurable benefits in return to sport and quality of life, but the authors correctly point out the need for a prospective randomized study on this subject.”

Nwachukwu acknowledged this, as well: “Based on the limitations of the data, our study is one data point that should be considered with prior studies and future studies when making a clinical decision on pediatric patients with this injury,” he said.

Finally, Blakemore pointed out why it’s important to make a distinction based on patients’ activity level: “For less active individuals, the benefits of early surgery may not be as clear, and in those patients in particular, I believe a trial of conservative treatment is still appropriate,” she said.

Nwachukwu and his coauthors intend to continue exploring this topic by further analyzing whether highly functioning athletes benefit more in terms of quality of life and other areas from surgery than conservative care. They also plan to establish a prospective registry for patellar dislocation in which they can follow patients regardless of their treatment and track their outcomes in a longitudinal fashion.

Greg Gargiulo is a freelance medical writer based in San Francisco.


Nwachukwu BU, So C, Schairer WW, et al. Surgical versus conservative management of acute patellar dislocation in children and adolescents: a systematic review. Knee Surg Sports Traumatol Arthrosc 2016;24(3):760-767.

Cash JD, Hughston JC. Treatment of acute patellar dislocation. Am J Sports Med 1988;16(3):244-249.

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