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Acute Patellar Dislocation in Children and Adolescents: A Randomized Clinical Trial

Palmu, Sauli BM; Kallio, Pentti E. MD, PhD; Donell, Simon T. FRCS(Orth), MD; Helenius, Ilkka MD, PhD; Nietosvaara, Yrjänä MD, PhD

Journal of Bone & Joint Surgery - American Volume: 01 March 2008 - Volume 90 - Issue 3 - p 463–470
doi: 10.2106/JBJS.G.00072
Scientific Articles

Background: The treatment of acute patellar dislocation in children is controversial. Some investigators have advocated early repair of the medial structures, whereas others have treated this injury nonoperatively. The present report describes the long-term subjective and functional results of a randomized controlled trial of nonoperative and operative treatment of primary acute patellar dislocation in children less than sixteen years of age.

Methods: The data were gathered prospectively on a cohort of seventy-four acute patellar dislocations in seventy-one patients (fifty-one girls and twenty boys) younger than sixteen years of age. Sixty-two patients (sixty-four knees) without large (>15 mm) intra-articular fragments were randomized to nonoperative treatment (twenty-eight knees) or operative treatment (thirty-six knees). Operative treatment consisted of direct repair of the damaged medial structures if the patella was dislocatable with the patient under anesthesia (twenty-nine knees) or lateral release alone if the patella was not dislocatable with the patient under anesthesia (seven knees). All but four patients who underwent operative treatment had a concomitant lateral release. The rehabilitation protocol was the same for both groups. The patients were seen at two years, and a telephone interview was conducted at a mean of six years and again at a mean of fourteen years. Fifty-eight patients (sixty-four knees; 94%) were reviewed at the time of the most recent follow-up.

Results: At the time of the most recent follow-up, the subjective result was either good or excellent for 75% (twenty-one) of twenty-eight nonoperatively treated knees and 66% (twenty-one) of thirty-two operatively treated knees. The rates of recurrent dislocation in the two treatment groups were 71% (twenty of twenty-eight) and 67% (twenty-four of thirty-six), respectively. The first redislocation occurred within two years after the primary injury in twenty-three (52%) of the forty-four knees with recurrent dislocation. Instability of the contralateral patella was noted in thirty (48%) of the sixty-two patients. The only significant predictor for recurrence was a positive family history of patellar instability. The mode of treatment and the existence of osteochondral fractures had no clinical or significant influence on the subjective outcome, recurrent patellofemoral instability, function, or activity scores.

Conclusions: The long-term subjective and functional results after acute patellar dislocation are satisfactory in most patients. Initial operative repair of the medial structures combined with lateral release did not improve the long-term outcome, despite the very high rate of recurrent instability. A positive family history is a risk factor for recurrence and for contralateral patellofemoral instability. Routine repair of the torn medial stabilizing soft tissues is not advocated for the treatment of acute patellar dislocation in children and adolescents.

Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

1Rakuunantie 18 A 21, FIN-00330 Helsinki, Finland. E-mail: sauli.palmu@helsinki.fi

2Children's Hospital, Helsinki University Central Hospital, Stenbäckinkatu 11, FIN-00290 Helsinki, Finland

3Institute of Health, University of East Anglia, Norwich, NR4 7TJ, United Kingdom

Copyright 2008 by The Journal of Bone and Joint Surgery, Incorporated
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