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Salter-Harris Type III Fractures of the Distal Femur: Plain Radiographs can be Deceptive

Lippert, William C. MPH*; Owens, Richard F. MD; Wall, Eric J. MD*

Journal of Pediatric Orthopaedics: September 2010 - Volume 30 - Issue 6 - p 598–605
doi: 10.1097/BPO.0b013e3181e4f55b
Lower Extremity
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Background Salter-Harris (SH) III fractures of the distal femur, although rare, can have devastating effects. The purposes of this study were to: (1) compare the intra-articular fracture displacement measured on plain x-ray and magnetic resonance imaging (MRI) or computed tomography (CT) scan and (2) report the outcomes of patients with a SH III fracture of the distal femur.

Methods All SH III distal femur fractures treated at a large Children's Hospital with a Level I Pediatric Trauma Center between 1995 and 2006 were retrospectively reviewed. A total of 14 patients (average age: 13 y, 11 mo; range: 7 y, 8 mo to 17 y, 11 mo) with an average follow-up time of 21.50 months (range: 2 to 47 mo) were included in this study. Fracture displacement on plain x-ray was compared with the fracture displacement measured on MRI or CT scan. The average time between the initial plain x-ray and MRI or CT scan was 37.48 days (range: 3 h to 6 mo).

Results Plain x-rays significantly underestimated the displacement of SH III fractures versus MRI or CT scan. Six patients who had both plain x-ray and MRI or CT scan had a measured displacement of 0.42 mm and 2.70 mm, respectively (paired Student t test, P=0.005). Ten of the 14 patients (71%) had no physical limitations and full knee motion at their most recent follow-up visit. The treatment of 4 patients (29%) was changed based on the findings of the additional MRI or CT scan.

Conclusions This study and earlier studies have shown a high rate of poor results with SH III fractures of the distal femur. This type of fracture pattern is extremely unstable and the true displacement is often underestimated by x-rays. Thus, it is strongly recommended that an MRI or CT scan be obtained on every SH III fracture of the distal femur. Moreover, any SH III fracture visible on plain radiographs should be treated with open reduction, internal fixation.

Level of Evidence Level IV.

*Cincinnati Children's Hospital Medical Center, Division of Orthopaedics, Cincinnati, OH

Department of Orthopaedic Surgery, Allegheny General Hospital, Pittsburgh, PA

No authors received financial support for this study.

Reprints: Eric J. Wall, MD, Cincinnati Children's Hospital Medical Center, Division of Orthopaedics, 3333 Burnet Avenue, MLC 2017, Cincinnati, OH 45229. e-mail: eric.wall@cchmc.org.

© 2010 Lippincott Williams & Wilkins, Inc.