Most school-aged children carry backpacks regularly, often loaded withheavy books and other items that can add up to a substantial amount ofweight. In fact, studies indicate that backpacks are often loaded with10-22 per cent of a child’s body weight 1, 2!
Article title: The effect of backpacks on the lumbar spine in children
A standing Magnetic Resonance Imaging study
Authors: Neuschwander TB, Cutrone J, Macias BR et al.
Publication information: Spine 2010; 35(1): 83-88
Most school-aged children carry backpacks regularly, often loaded with heavy books and other items that can add up to a substantial amount of weight. In fact, studies indicate that backpacks are often loaded with 10-22 per cent of a child’s body weight 1, 2! When worn up to 60 minutes a day, it is understandable that growing concern exists regarding the relationship between carrying heavy backpacks and back pain in children. Roughly 40 per cent of children report back pain and many of them attribute this pain to backpack use3. Further, a recent study4 revealed that contact pressure under backpack straps can be substantial, and result in pain in children.
To date, there has not been a radiographic study investigating the response of the pediatric spine to backpack loads in a standing position. This study utilized a new standing magnetic resonance imaging (MRI) technique to provide detailed analysis of intervertebral disc compression and spinal curvature changes in response to increasing backpack loads in children, without the associated risks of radiation that accompany other imaging methods.
- Increasing backpack loads of four, eight and 12 kilogram significantly compressed lumbar discs in a linear fashion in the sagittal plane (P < 0.05).
- The L5-S1 disc was more “compressible” – displaying compression of up to two times that of the T12-L1 disc.
- Subjects reported significantly higher pain (up to ~50 per cent) with higher backpack loads (P < 0.001). This relationship was linear (r2=0.711), but this may have been a result of subjects being aware that the load was increasing.
- No statistically significant relationship was identified between spinal load and lordosis (although a trend was noticed).
- Although the correlation coefficient was small (r2=0.124), increasing backpack loads increased coronal spinal asymmetry – this was most noticeable with the eight-kilogram load (9.18°±2.25°). With the 12-kilogram load, subjects were observed adjusting their posture more frequently, which may have altered this measurement (and measurement of lordosis above).
- Four of the eight subjects displayed Cobb angles > 10° during loading.
CONCLUSIONS AND PRACTICAL APPLICATION
As spine care experts, we are well positioned to discuss this issue with our school-aged patients and their parents. In addition to dealing with related musculoskeletal pain when it arises, practitioners should educate patients about minimizing backpack load, maintaining proper posture, backpack use (always two straps!), and employing tissue sparing techniques.
Recently, profession-wide initiatives have been aimed at educating the public on this issue. The findings of this study could now be included in this information and help us stay on the cutting edge of emerging scientific literature on this topic.
This study employed a simple yet appropriaterepeated measures design. Eight students(three boys and five girls, age 11 ± 2) participated, all having no history of backpain, scoliosis, or spine surgery. Eachsubject was between the 25th-75th percentile in bodyweight for their age, representing an “average” sized child.
After resting supine for 30 minutes, subjectsunderwent sagittal T2 MRI scans – first supine, then standing up. Another MRI was taken after adding astandardized backpack containing 4Kg of ceramic tiles worn with two shoulderstraps. This process was then repeatedfor backpacks containing 8 and 12Kg of tiles (these loads representedapproximately 10, 20 and 30% bodyweight). For each trial, subjects wore the backpack for 10 minutes and reportedtheir pain levels using a Visual Analogue Scale. For each MRI image, disc height was measuredfrom T12-L1 to L5-S1 (defined as the average between anterior and posteriordisc height at each level). “Compressibility”was reported as post-loading disc height minus supine disc height. Lumbar curvature was measured using the Cobbmethod (superior endplates of L1 and S1).
Thisstudy employed a simple design and used reasonable backpack loads and outcomes. The authors also employed an appropriateimaging technique that allows precise measurements while eliminating radiationexposure for their young subjects.
However, the results of this study should beinterpreted while keeping the following limitations in mind:
· A lumbar coil was used for imaging, thus notallowing imaging of the entire spine -this may have affected curvature measurements.
· Time of day was not controlled for (the spinalcolumn shortens throughout the day ) – each subject had been ambulatory forat least 60 minutes prior to the 30 minute supine resting period.
· Each backpack load was worn for only 10 minutes –children typically wear their backpacks for longer periods of time, so theeffects seen in this study may have been greater if longer loading periods wereutilized.
· The outcomes measured were not specific to low backpain, and may have captured shoulder, thoracic spine, or other complaints.
1) Watson KD, Papageorgiou AC, Jones GT et al. Lowback pain in school children: occurrence and characteristics. Pain 2002; 97:87-92.
2) Negrini S, Carabolana R, Sibilla P. Backpack as adaily load for schoolchildren. Lancet 1999; 354: 1974.
3) Skaggs DL, Early SD, D’Ambra P et al. Back pain andbackpacks in school children. J Pediatr Orthop 2006; 26: 358-363.
4) Macias BR, Murthy G, Chambers H et al. High contactpressures beneath backpack straps of children contributes to pain. Arch PediatrAdolesc Med 2005; 159: 1186-1187.
5) Tyrell AS, Reilly T, Troup JD. Circadianvariation in stature and the effects of spine loading. Spine 1985; 10: 161-164.
This brief review is a sample of the content posted weekly on Research Review Service and is one of over 60 reviews available per year of the latest scientific literature in chiropractic. RRS is approved for 4.0 CEUs/year by CMCC.
Dr. Shawn Thistle is the founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners to integrate current, relevant scientific evidence into their practice. Shawn graduated from CMCC and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider. For more information about the Research Review Service, visit www.researchreviewservice.com .
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