Low Back Pain In Children: Natural History and Value of Diagnostic Radiologic Studies

Saturday, October 15, 2011: 8:00 AM
Otis (Westin Waterfront)
Robert A. Miller, BS1, Nicholas A. Beck, BS1, Norma Rendon Sampson, MS1, Xiaowei Zhu, MS2, John M. Flynn, MD1 and Denis Drummond, MD1, (1)Division of Orthopaedic Surgery, Children's Hospital of Philadelphia, Philadelphia, PA, (2)Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA

Purpose: Mechanical low back pain is common in the pediatric population; recent studies have shown that undiagnosable mechanical low back pain (UMLBP) is common in adolescents, accounting for up to 78% of cases.  Spondylolysis/spondylolisthesis is the most common pathologic cause of back pain in this age group.  The goals of this study are to: determine the natural history of low back pain, evaluate the value of radiographic studies in establishing a diagnosis of spondylolysis, and determine the cost and radiation effective doses (EDs) associated with those studies.

Methods: A retrospective review of patients records aged 10-19 years who presented to our institution with mechanical low back of undiagnosed etiology from 1/1/2000 – 1/1/2008 were identified.  Patients with previous back surgery, high energy trauma, congenital syndromes, or medical co-morbidities were excluded.  UMLBP was defined as back pain with etiology undetected on examination and imaging.  Age-specific radiation EDs were calculated for 0-15 years, 16-18 years, and >18 years year for plain films, fine cut 2-level L-spine CT scans (CTs), and bone scans (BSs).

Results: 2846 patients (63% female) with average age of 14.3 years were identified.  2244 (79%) patients had UMLBP, over 90% of which had <3 office visits.  272 patients (9.6%) were diagnosed with spondylolysis; 234 (86%) by plain film, 34 (12.5%) by BSs, and 4 (1.5%) by CTs.  Most (74%) patients with spondylolysis had a positive plain film study.  There was no significant difference between 2-view (AP, LAT) and 4-view (AP, LAT, ROB, LOB) studies in sensitivity (78% vs. 72%, p=0.39).  Advanced imaging was pursued in 90/354 (25%) patients with negative plain film studies.  Of these, 53% of BSs performed were positive and 27% of CTs performed were positive (p=0.02).  BSs exposed patients to much more radiation than CTs and plain film studies.  Costs and age-specific radiation EDs for diagnostic studies are outlined in Table 1.

Conclusion: Mechanical low back pain is common in adolescents and in most cases is undiagnosed; most require no imaging and <3 office visits.  For spondylolysis, 2-view plain films are often diagnostic and oblique views did not add value.  Advanced imaging increases diagnostic accuracy, but adds considerable cost and radiation exposure.  Because diagnosis of spondylolysis rarely changes clinical management, physicians should use these studies sparingly in children.

Table 1.  Costs and age-specific radiation effective doses for diagnostic studies.

Cost Effective Dose (mSv)
0-18 y/o 0-15 y/o 16-18 y/o >18 y/o
2-view $364 0.7 0.8 0.7
4-view $511




CT $2,011 1.5 1.7 1.7
BS $1,660 8.3 7.2 6.7

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