Ligament Reconstruction Reduces Kneecap Dislocations in Children With Patellar Instability

Jim Kling

October 04, 2010

October 5, 2010 (San Francisco, California) — Children with patellar instability have good short-term results after reconstruction of the medial patellofemoral ligament (MPFL), according to a study presented here at the American Academy of Pediatrics 2010 National Conference and Exhibition.

MPFL reconstruction has been well studied in adults with patellar instability, but use of the technique is controversial in children. "Historically, there have not been a lot of great options [for children with patellar dislocations]," Jennifer Weiss, MD, assistant professor of orthopedics at Children's Hospital Los Angeles, California, who presented the study findings, told Medscape Medical News.

The researchers conducted a retrospective review of MPFL reconstructions performed by a single surgeon at their institution. The sample consisted of 27 patients who had 29 knee operations over a 3-year period. The average age of the patients was 14.4 years (range, 7 to 18 years). There were 13 female patients (48%) and 14 male patients (52%). The surgeon operated on 12 left knees (41%) and 13 right knees (45%); 2 patients (7%) underwent bilateral procedures.

The surgeon performed patellar fixation using a biotenodesis screw. Femoral fixation was achieved at the adductor tubercle by interference screw. The surgeon used arthroscopy to evaluate the joint and performed a lateral release, when indicated, for lateral patellar tilt. The researchers conducted a chart review that included postoperative range of motion, complications, and incidence of redislocation.

After a mean follow-up of 7 months, 3 patients (11%) developed complications: 1 patient each experienced recurrent instability, stiffness that required manipulation under anesthesia, and a traumatic patella fracture.

In all, 24 patients (89%) achieved full range of motion. Eight patients responded to postoperative questionnaires, including the International Knee Documentation Committee Subjective Knee Evaluation Form (mean, 73.71; range, 58.62 to 97.70), the Lysholm Knee Score (mean, 86.57; range, 57 to 100), and the Tegner Activity Score (mean, 5.3; range 1 to 7).

"The kids who mimic sports injuries in adults have done amazingly well with this surgery," said Dr. Weiss. She noted that the complications occurred in children with cerebral palsy and Down's syndrome. "It [might be that] the unique nature of some of these kids who have [problems] like cerebral palsy [means that] previous studies haven't picked them out as not doing [well]. Their muscles are different. They're overactive in some places and underactive in others, so their balancing is much different. They're going to stress whatever we do with their surgery in a different, more demanding way."

Some patients presented with patellar instability because of traumatic events, whereas others are "habitual dislocators," who suffer a kneecap dislocation just from bending a knee, according to Dr. Weiss. Both groups of patients do well with this surgery "as long as they don't have something like Down's syndrome or cerebral palsy. For patients with such comorbidities, we need to consider adding something [for additional stability]."

"It's a nice focus, because if you can fix that anatomic tear, it's almost akin to repairing the [anterior cruciate ligament]. You can hopefully give stability back to that patellar femoral joint. They had a very reasonable failure rate (about 16%)," William Hennrikus, MD, associate dean and professor of orthopedics and pediatrics at Penn State Medical School in Hershey, Pennsylvania, who attended the session, told Medscape Medical News.

Dr. Hennrikus noted that treatment hasn't stood the test of time. "We need to keep watching. There are 5 or 6 treatment choices, but none of them works in every case."

The study did not receive commercial support. Dr. Weiss and Dr. Hennrikus have disclosed no relevant financial relationships.

American Academy of Pediatrics (AAP) 2010 National Conference and Exhibition: Abstract 9235. Presented October 2, 2010.

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