Extrinsic causes may include traumatic dislocation during the birthing process3 or intrauterine pressure leading to malposition of the joints. When intrauterine pressure is combined with reduced intrauterine space, this phenomenon is known as packaging disorder.6 Entanglement of the umbilical cord around the legs of the fetus during development may be another potential factor.1Of note: Cases involving both extrinsic or intrinsic etiologies can present with associated abnormalities that include congenital dislocation of the hip, congenital hip dysplasia, spina bifida, and/or cleft palate—in addition to knee hyperextension.
The exact etiology in our patient was unknown, but we determined the cause was extrinsic based on the lack of other genetic abnormalities. We initially considered a possible connection between our patient’s diagnosis and her family history of thrombocytopenia absent radius syndrome, but it was later determined that both were isolated cases and the limb abnormalities were coincidental.
Treatment options and outcomes for extrinsic and intrinsic etiologies depend on the severity of the hyperextension and any associated abnormalities, as well as the time in which therapy is initiated.1 Reduction of the hyperextension within 24 hours of birth has been associated with excellent outcomes.8 Regardless of the cause, all cases of congenital genu recurvatum should first be treated conservatively. Evidence has suggested that conservative therapy involving early gentle manipulation of the knee combined with serial splinting and casting should be the first line of treatment.6 If initial treatment attempts fail or in cases occurring later in life, surgical interventions (eg, quadriceps release procedures such as percutaneous quadriceps recession or V-Y quadricepsplasty, proximal tibial closing-wedge, anterior displacement osteotomy) likely is warranted.6,9
Our patient. At 1 week of life, our patient’s short leg splints were replaced with long leg splints with a maximal flexion of 20° to 30° (FIGURE 1B). Weekly follow-ups with serial casting were initiated in the pediatric orthopedics clinic. At 3 weeks of life, the patient’s knee flexion had improved and the splints were removed (FIGURE 1C). Upon clinical examination, the bilateral knees were extended to a neutral position, and both could be actively and passively flexed to 90°. The patient was referred to Physical Therapy to perform range of movement exercises on the knees.
IMAGE COURTESY OF: METROHEALTH MEDICAL CENTER, CASE WESTERN RESERVE UNIVERSITY, CLEVELAND, OHIO
At 8 weeks of life, the bilateral legs were in full extension, and knee flexion was up to 130°. Physical therapy for knee range of movement exercise was continued on a weekly basis until 6 months of life, then twice monthly until the patient was 1 year old. Ultimately, the hyperextension was corrected, and the patient started walking at around 16 months of age. Her prognosis is good, and she will be able to participate in low-impact sports, after consulting with her orthopedist.
IMAGE COURTESY OF: METROHEALTH MEDICAL CENTER, CASE WESTERN RESERVE UNIVERSITY, CLEVELAND, OHIO
Continue to: THE TAKEAWAY