Adolescent idiopathic scoliosis and back pain
Pain associated with scoliosis
Regarding associated symptoms, a German study evaluated the data of more than 640,000 youths included in an insurance database. ICD diagnosis codes M40-43 would be relevant for the purpose of our review (M40: kyphosis and lordosis; M41: scoliosis; M42: spinal osteochondrosis; and M43: other deforming dorsopathies). For scoliosis, data from 2002 showed the following means in % (girls/boys) for prevalence at 0–14 years of age and at 15–24 years: M41: 2.31 (2.51/2.12) and 3.44 (3.80/3.07) [18]. Ramirez et al. [19] reported on more than 2400 subjects with AIS. Of these, 23 % reported back pain at the time of diagnosis. An additional 9 %, initially free of pain and managed with observation alone, developed pain during follow-up. A study from Japan including more than 30,000 adolescents concluded that the subgroup with scoliosis had an approximately 3 to 5 fold increased point and lifetime prevalence of backache in the upper and middle right part of the back [20]. In a prospective multicentre study, Lonner et al. [21] compared three groups of adolescents including 894 with AIS and 31 healthy controls. The pain scores on the specific subdomain of the SRS-22 questionnaire were 4.15 in the scoliosis group and 4.24 among the controls, which is not a significant difference.
A retrospective chart review of a random sample of 310 individuals (10–17 years) selected from all cases of AIS referred to a Canadian university hospital has been published recently [22]. The authors concluded that the prevalence of back pain was “moderately high” but the reported data on pain do not seem very homogeneous (gathered by the attending physicians, or reported by medical references, or by letters from the parents, narrative or through a pain score, with or without a specific topography of pain recorded, etc.). Of note, severe pain was documented in only 1 % of the charts [22].
A prospective multicentre study including 744 patients (621 females) surgically treated for AIS addressed the differences between genders in functional outcome. Before surgery, males were aged an average of 15.2 years and females 14.0 years (p??0.001) with no significant differences in maximum Cobb angles (F: 53.3° and M: 55.9°) or Risser grades (F: 3.2 and M: 3.5) [23]. At baseline, the scores on the pain domain of the SRS-30 were 4.1 among girls and 4.3 in boys, below the statistical significance threshold [23].
A recent meta-analysis has been published comparing selective versus non-selective thoracic fusion in Lenke 1C curves [24]. Preoperative data on pain using the SRS-22 has shown slightly different scores between the two groups that is 4.13 (0.77) in the selective fusion group versus 3.92 (0.79) in those undergoing non-selective procedures. The difference is statistically significant (p?=?0.038), but is at the limit of the minimum clinically important difference (MCID), reported to be 0.20 [21, 25, 26]. As any other tool, the questionnaires used to gather information on patients with scoliosis have some limitations. An American study evaluated SRS-22 performance in 450 healthy adolescents (mean age: 16 years; range: 9.3 to 21.8 years). Concerning specifically pain, the mean score was 4.3?±?0.6 with males scoring a bit higher (actual figures by gender not reported but r?=?0.103, p??0.05) [27]. Moreover, ethnicity was also a significant factor with African Americans scoring significantly higher at 4.5 (i.e. less pain) than Hispanics (4.3). Other socio-demographic variables were significantly associated with different domains of the questionnaire [27].
Other studies have also shown that culture and ethnicity have an influence on outcomes with Caucasians reporting more pain than East Asians on the SRS-30 [28, 29]. Finally, in a Polish study, the living environment has also been reported to influence the results of the SRS-24 questionnaire, with rural patients reporting more pain than those from an urban environment [30].
The Pediatric Outcomes Data Collection Instrument (PODCI), a multidimensional tool developed in North America (also known as POSNA for Pediatric Orthopedic Society of North America) [31], was used to evaluate 102 patients with AIS (as well as other groups of patients with different pathologies) [32]. Scores of these patients were compared to those of a small group of 27 “healthy” adolescents evaluated in a different study [33]. Of these 102 patients, 95 (86 girls) filled in the patient questionnaire. The scores of the two groups for the comfort/pain scale were 86.7?±?14.5 for the healthy group versus 75.2?±?22.4 for the AIS group. Each dimension is scaled from 0 to 100, with 100 the most favourable outcome. The result is statistically significant at p??0.05; however, the differences between the two groups do not seem clinically relevant when compared with the properties of the same tool described elsewhere [34].
Considering another perspective on the association between symptoms and scoliosis, a study carried out on 1743 men in the military (range: 18–30 years) found a prevalence of idiopathic scoliosis of 6.65 % among those with no symptoms and free of any lytic or olisthetic lesions [35]. Of note, none had a Cobb angle 20°. Prevalence ranged from 13.3 to 23.8 % in the symptomatic and asymptomatic subgroups with uni- or bilateral pars break and 18.3 % among those without any lesion of the posterior arch but reporting back pain.
Clark et al. [36] have just published the results of a prospective, population-based, birth cohort study with complete data on 3184 participants. Subjects were evaluated at age 15 for scoliosis using total-body dual-energy X-ray absorptiometry (DXA) and surveyed at age 18 for pain and function. A multivariable analysis shows a significant association between small spinal curves (?6°) at age 15 and self-reported back pain at age 18. Spinal curvature is also associated with days off school and avoidance of activities.
It appears quite clear from comparing the prevalence of back pain and scoliosis that the latter cannot be the main explanation for LBP for a majority of adolescents reporting such symptoms, although scoliosis playing a role in some patients cannot be ruled out. However, comparing the results of different studies does not allow any firm conclusions to be drawn on the possible causal relationship between different variables. Nevertheless, the compelling and overwhelming predominance of girls in the adolescent cohorts with idiopathic scoliosis (up to almost 90 % in some series, such as that published by Théroux et al. [22]) casts doubt on the aetiological role of scoliosis on back pain in the general population, at least among boys. Another piece of information that suggests a limited role of scoliosis in back pain is the weak or even absent correlation between the magnitude of the curves measured by the Cobb angle and the presence of pain [22, 28, 37, 38].
The main references quoted in this section are summarized in Table 1.
Summary of the main publications including data on pain presented in the order of citation in the manuscript
Reference 1st author/year
Design
Tools used for Pain
Results
Comments
N. Ramirez/JBJS 1997 [19]
Retrospective study of 2442 patients with AIS. Mean age was 14 years for those with back pain and 13 years for those who did not have pain.
History of back pain
Back pain was reported by 23 % at the time of presentation. Of 210 patients managed with observation only and who were pain-free initially, 9 % reported back pain during follow-up (about 3 years).
Pain was associated with age 15 years or Risser sign ?2 but not with gender, type or magnitude of the curves.
T. Sato/Eur Spine J 2011 [20]
Epidemiological study including 32,083 students without scoliosis and 51 with AIS. Age range was 9–15 years.
Questionnaire Severity of back pain defined according to functional limitation (3 categories)
Adjusted OR of back pain (point or lifetime prevalence) was 2.29 in the scoliosis group compared with the controls. Pain was also more severe, had longer duration and more recurrences in the scoliosis group.
The difference was highly significant only for pain located in the right scapular area. No difference was found for lumbar pain.
B. Lonner/Spine 2013 [21]
Prospective pretreatment multicenter and retrospective chart review including 894 patients with AIS (mean age 14.9 years) who were compared with 106 patients with Scheuermann’s kyphosis (mean age 16.1 years) and with 31 healthy adolescents (mean age 14.2 years).
SRS-22
Mean Pain scores were 4.15 in the AIS group versus 4.24 among healthy controls.
MCID for Pain was set at 0.2. Patients with Scheuermann kyphosis reported significantly more pain than AIS patients
J. Theroux/Pain Res Manag 2015 [22]
Retrospective review of a random sample of 310 charts of AIS adolescents. Mean age was 13.9 years for girls and 14.5 for boys.
Documentation of back pain from different sources. Previous surgery and other spinal pathologies were exclusion criteria.
Almost half of the patients (47.3 %) had chart-documented back pain, most frequently lumbar pain. Pain intensity was specified in only 21 % of charts and described as mild in 9.4 %, moderate in 11 % and severe in 1 % of cases. Pain intensity was not correlated with the Cobb angle.
No comparison group.
D.W. Roberts/Spine 2011 [23]
Longitudinal cohort study comparing outcomes before and after surgery. N?=?744 patients. Mean age was 15.2 years for boys and 14.0 in girls.
SRS-30
Preoperatively Pain scores were 4.1 for females and 4.3 for males. Of note, the latter were 1.2 years older than females (average age 15.2 versus 14.0 years).
Despite boys were significantly older, the baseline differences between genders were N.S.
A.J. Boniello/J Neurosurg Spine 2015 [24]
Meta-analysis of preoperative data limited to patients with Lenke type 1C curves. 1 prospective and 6 retrospective case-control studies. Overall 488 patients. Mean age for each group: 14.7 and 14.8 years (N.S.).
SRS-22
Baseline data from the largest multicenter study showed Pain scores of 4.13?±?0.77 in the group eventually undergoing selective fusion Vs 3.92?±?0.79 in those later fused nonselectively.
J. Bago/Eur Spine J 2009 [25]
Study designed to identify Minimal important differences in 91 AIS patients undergoing surgical procedures. Mean age was 18.1 years (range 10–38 years).
SRS-22
Preop scores were 3.8–3.9
MID for Pain dimensions was identified at 0.6
L.Y. Carreon/Spine 2010 [26]
Longitudinal cohort (735 girls 152 boys. Mean age 14.3 years) to evaluate MCID
SRS-22 SRS-30
Baseline scores for Pain: 4.1?±?0.71
MCID for Pain domain: 0.2
K. Verma/Spine 2010 [27]
Healthy adolescents. Anonymous survey N?=?450 / 16 (10–22) years
SRS-22
Mean score for Pain domain was 4.3?±?0.6. Males had higher score. African Americans scored higher than Hispanics.
Normative baseline in healthy adolescents
L.J. Morse/Spine 2012 [28]
Preoperative comparison of 6 ethnic groups of children with AIS. Total?=?1853 composed of US white (1234), black (213), Hispanic (78), and Asian (29), as well as native Japanese (192) and Koreans (107). Overall mean age was 14.85 years ranging from 14.34 (Hispanics) to 14.97 (white). There were statistically significant differences between groups in terms of age, gender, BMI, and major curve magnitude.
SRS-30
The scores for the Pain domain ranged from 4.52?±?0.51 among the Japanese patients, to 4.04?±?0.72 in the US white patients (P??0.001).
Whites reported more pain than Japanese and Koreans. The authors recommend taken into account cultural and ethnic differences when counseling patients.
K. Watanabe/Spine 2007 [29]
Comparison of 2 groups of 100 AIS patients each, one American and the other Japanese. Both groups were comparable with regard to age (mean age was 15.0 years in Americans and 14.9 years in Japanese), gender, curve location, Cobb angle and thoracic kyphosis.
SRS-24
Scores for the total pain domain were 3.7?±?0.8 among Americans and 4.3?±?0.4 in the Japanese group
The authors highlight the cultural differences and suggest that a cross-cultural comparison of the SRS-24 content is necessary.
E. Misterka/Med Sci Monit 2012 [30]
Retrospective study comparing 20 rural and 40 urban Female Polish patients with AIS with???2 years follow-up after surgery for AIS
SRS-24
Mean Pain scores were 4.4 in the urban group and 4.3 in the rural one (NS).
Some differences between groups were found but the authors did not end-up with strong conclusions based on the environment.
J.A. Lerman/Spine 2002 [32]
102 adolescents with AIS (15.3 years), 47 with congenital scoliosis and 84 “normals”.
PODCI (Pediatric Outcomes Data Collection Instrument). All dimensions scaled 0–100 where highest is best.
Comfort/Pain scores self reported by adolescents (N?=?95) (parents’ questionnaires NOT included here) respectively were 86.7?±?14.5 for “Normals” and 75.2?±?22.4 in the AIS group (P??0.05)
No significant differences in Comfort/pain scores according to age, Cobb angle or curve location.
R.J. Haynes/J Pediatr Orthop 2001 [33]
Only the 1st administration of the questionnaire included. Parents’ questionnaire for patients 2–18 years. Patients’ questionnaire for those aged 11–18 years.
POSNA (Pediatric Orthopaedic Society of North America)
L.N. Pellegrino/J Spinal Disord Tech 2014 [37]
Prospective observational study pre- and postoperative of 33 patients (mean age 15.6 years).
SRS-30 and SF-36
Preop mean SRS pain score was 3.95?±?0.09 and SF-36 61.00?±?4.20
P.R.P. Rushton/Spine 2013 [55]
Review and statistical analysis of the literature. Data on pain were available from 21 cohorts from 15 published studies.
SRS-22r
In 17 cohorts AIS patients reported statistically more pain than controls, in 3 cohorts patients and controls scored similarly, and in 1 study patients had less pain. However, in only 1 study was the difference clinically relevant (MCID)
E.M. Clark/Spine 2016 [36]
Prospective, population-based, birth cohort study. Subjects with spinal curve???6° at the age 15 (N?=?202/3184) were surveyed for back pain at age 18
1ary outcome: Pain (?1 day in the prev. month).
At age 15 202 subjects had spinal curves ?6°. Median curve size 11°. Curves ?25° were found in 11 participants.
Spinal curves were identified using the DXA scoliosis method.
2ary outcomes: Self-reported days off activities
Back pain was reported by 21.3 % of the subjects with curves versus 16 % of those without.
?7 days off activities in the last 6 months were reported by 21.7 % of those with spinal curves versus 12.3 % of the controls.