AJR:204, April 2015 W461 gression of slippage is thought to be mini- mal after the age of 16 years [11]. Beutler et al. [13] followed a cohort of subjects with isthmic spondylolisthesis over a period of 45 years and found that slip progression slowed with each decade. Degenerative spondylolisthesis, although progressive, rarely exceeds grade II [14]. Spur formation, sclerosis, and ossification of ligaments limit the progression of degen- erative spondylolisthesis [15]. Huang et al. [16] found that 20.9% of a cohort of 86 sub- jects had arthrodesis accompanying spondy- lolisthesis. Subjects with spontaneous fusion were, on average, 10 years older than subjects without arthrodesis. Newman [17] noted that spondylolisthesis could occur with an intact neural arch in the presence of facet joint de- generation and may have been the first to call this entity “degenerative spondylolisthesis.” Meyerding [18] developed a grading sys- tem that measures the amount of slippage as a percentage of the diameter of the verte- bra below the slippage. He defined grade I as 0–25% displacement, grade II as 26–50% displacement, grade III as 51–75% displace- ment, and grade IV as 76-100% displacement, and grade V (spondyloptosis) as greater than 100%. Grades I and II are considered low- grade. Keep in mind that Meyerding’s grad- ing of spondylolisthesis does not necessarily Functional Radiography in Examination of Spondylolisthesis Justin R Câmara 1 Joseph R. Keen 2 Farbod Asgarzadie 2 Câmara JR, Keen JR, Asgarzadie F 1 Loma Linda University, 11234 Anderson St, Loma Linda, CA 92354. Address correspondence to J. R. Câmara ([email protected]). 2 Department of Neurological Surgery, Loma Linda University, Loma Linda, CA. Musculoskeletal Imaging • Review WEB This is a web exclusive article. AJR 2015; 204:W461–W469 0361–803X/15/2044–W461 © American Roentgen Ray Society S pondylolisthesis is the anterior slippage of one vertebra relative to the inferior vertebra [1]. Mul- tiple classification systems have been proposed for spondylolisthesis [2–5], but commonly used classifications are dys- plastic, isthmic, degenerative, traumatic, and pathologic [1]. Isthmic spondylolisthesis is by definition always accompanied by and is often preceded by spondylolysis, a defect in the pars interarticularis that allows the verte- bral body to slip anteriorly, especially during a growth spurt. The term “spondylolysis” re- fers strictly to defects in the pars interarticu- laris that may or may not be accompanied by vertebral slippage. The slippage in this case would be termed “isthmic spondylolisthesis” [6, 7]. Degenerative spondylolisthesis, on the other hand, occurs in the absence of pars in- terarticularis defects. The entire vertebra in- cluding the arch slips anteriorly relative to the inferior vertebra [8]. Kalichman et al. [9] found that the preva- lence of spondylolysis diagnosed using CT in a community-based population was 11.5%, which is a much higher prevalence than re- ported in previous studies using convention- al radiography. Spondylolysis progresses to isthmic spondylolisthesis in a significant fraction of cases, with reports of progression in up to 80% of cases [10–12]; however, pro- Keywords: degenerative spondylolisthesis, flexion- extension, functional radiography, instability, isthmic, spondylolisthesis, translation DOI:10.2214/AJR.14.13139 Received May 14, 2014; accepted after revision July 24, 2014. OBJECTIVE. Despite the predominant use of standing flexion-extension radiography for quantifying instability in isthmic and degenerative spondylolisthesis, other functional radio- graphic techniques have been presented in the literature. CONCLUSION. The current evidence reported in the literature is insufficient to influ- ence how the results of these other functional radiographic techniques should affect clinical management; however, it does raise doubts regarding the accuracy and reliability of stand- ing flexion-extension radiography in this setting. Based on the currently available evidence and until randomized studies are performed to assess the efficacy of functional radiographic techniques in directing clinical decision making, positioning schemes other than traditional standing flexion-extension may be considered as options in the evaluation of patients with symptomatic isthmic and degenerative spondylolisthesis in which standard flexion-extension radiographs fail to show pathologic instability. Câmara et al. Functional Radiography of Spondylolisthesis Musculoskeletal Imaging Review Downloaded from www.ajronline.org by 117.3.252.4 on 04/13/23 from IP address 117.3.252.4. Copyright ARRS. For personal use only; all rights reserved
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Functional Radiography in Examination of SpondylolisthesisAJR:204, April 2015 W461
gression of slippage is thought to be mini- mal after the age of 16 years [11]. Beutler et al. [13] followed a cohort of subjects with isthmic spondylolisthesis over a period of 45 years and found that slip progression slowed with each decade.
Degenerative spondylolisthesis, although progressive, rarely exceeds grade II [14]. Spur formation, sclerosis, and ossification of ligaments limit the progression of degen- erative spondylolisthesis [15]. Huang et al. [16] found that 20.9% of a cohort of 86 sub- jects had arthrodesis accompanying spondy- lolisthesis. Subjects with spontaneous fusion were, on average, 10 years older than subjects without arthrodesis. Newman [17] noted that spondylolisthesis could occur with an intact neural arch in the presence of facet joint de- generation and may have been the first to call this entity “degenerative spondylolisthesis.”
Meyerding [18] developed a grading sys- tem that measures the amount of slippage as a percentage of the diameter of the verte- bra below the slippage. He defined grade I as 0–25% displacement, grade II as 26–50% displacement, grade III as 51–75% displace- ment, and grade IV as 76-100% displacement, and grade V (spondyloptosis) as greater than 100%. Grades I and II are considered low- grade. Keep in mind that Meyerding’s grad- ing of spondylolisthesis does not necessarily
Functional Radiography in Examination of Spondylolisthesis
Justin R Câmara1
Joseph R. Keen2
Câmara JR, Keen JR, Asgarzadie F
1Loma Linda University, 11234 Anderson St, Loma Linda, CA 92354. Address correspondence to J. R. Câmara ([email protected]).
2Department of Neurological Surgery, Loma Linda University, Loma Linda, CA.
Musculoskeleta l Imaging • Review
AJR 2015; 204:W461–W469
© American Roentgen Ray Society
S pondylolisthesis is the anterior slippage of one vertebra relative to the inferior vertebra [1]. Mul- tiple classification systems have
been proposed for spondylolisthesis [2–5], but commonly used classifications are dys- plastic, isthmic, degenerative, traumatic, and pathologic [1]. Isthmic spondylolisthesis is by definition always accompanied by and is often preceded by spondylolysis, a defect in the pars interarticularis that allows the verte- bral body to slip anteriorly, especially during a growth spurt. The term “spondylolysis” re- fers strictly to defects in the pars interarticu- laris that may or may not be accompanied by vertebral slippage. The slippage in this case would be termed “isthmic spondylolisthesis” [6, 7]. Degenerative spondylolisthesis, on the other hand, occurs in the absence of pars in- terarticularis defects. The entire vertebra in- cluding the arch slips anteriorly relative to the inferior vertebra [8].
Kalichman et al. [9] found that the preva- lence of spondylolysis diagnosed using CT in a community-based population was 11.5%, which is a much higher prevalence than re- ported in previous studies using convention- al radiography. Spondylolysis progresses to isthmic spondylolisthesis in a significant fraction of cases, with reports of progression in up to 80% of cases [10–12]; however, pro-
Keywords: degenerative spondylolisthesis, flexion- extension, functional radiography, instability, isthmic, spondylolisthesis, translation
DOI:10.2214/AJR.14.13139
Received May 14, 2014; accepted after revision July 24, 2014.
OBJECTIVE. Despite the predominant use of standing flexion-extension radiography for quantifying instability in isthmic and degenerative spondylolisthesis, other functional radio- graphic techniques have been presented in the literature.
CONCLUSION. The current evidence reported in the literature is insufficient to influ- ence how the results of these other functional radiographic techniques should affect clinical management; however, it does raise doubts regarding the accuracy and reliability of stand- ing flexion-extension radiography in this setting. Based on the currently available evidence and until randomized studies are performed to assess the efficacy of functional radiographic techniques in directing clinical decision making, positioning schemes other than traditional standing flexion-extension may be considered as options in the evaluation of patients with symptomatic isthmic and degenerative spondylolisthesis in which standard flexion-extension radiographs fail to show pathologic instability.
Câmara et al. Functional Radiography of Spondylolisthesis
Musculoskeletal Imaging Review
Câmara et al.
signify instability [19]. The term “spondylop- tosis” is reserved for 100% displacement of the superior vertebra [20].
The choice of vertebral landmarks used to measure the degree of slippage is debat- able and varies among studies [21–23]. Stand- ing conventional radiographs from the lateral view are often used to identify spondylolis- thesis, whereas standing flexion-extension ra- diographs are commonly used to quantify the degree of intervertebral instability [24–31]. Although not sufficient alone, standing flex- ion-extension radiographs are often used in combination with clinical signs and symptoms to choose between conservative management and surgery—specifically, fusion [32–40]. The relationship between radiographically visible instability and clinical findings is un- clear. Some studies have found that instabil- ity seen on functional radiographs correlates well with symptoms of low back pain [41, 42], whereas other studies have not found this rela- tionship to hold true [24, 43]. Currently, func- tional radiography is most useful when its findings agree with the larger context of clini- cal signs and symptoms [44, 45].
Despite the predominant use of standing flexion-extension radiographs for quantify- ing instability in isthmic and degenerative spondylolisthesis, other forms of functional radiography have been proposed and eval- uated in the literature [24, 29, 46–56]. The purpose of this article is to evaluate the evi- dence for various forms of functional radiog- raphy with potential usefulness in examining instability in patients with isthmic spondylo- listhesis and in those with degenerative spon- dylolisthesis. The term “instability” as used here refers to the acute motion of the verte- brae at the level of spondylolisthesis as a re- sult of external forces such as weight, trac- tion, or a change in body position.
Materials and Methods A search of the PubMed database was performed
for articles published in English through April 2013 that included any of the following terms: spondylo- listhesis intervertebral instability, spondylolisthesis prone radiography, spondylolisthesis supine radiog- raphy, spondylolisthesis traction radiography, spon- dylolisthesis flexion-extension radiography, spondy- lolisthesis instability radiography, spondylolisthesis recumbent radiography, spondylolisthesis dynamic radiography, spondylolisthesis functional radiogra- phy, and spondylolisthesis stress radiography. The search yielded a total of 887 results. Additionally, the related citations generated by PubMed and the bibliographies of relevant articles were checked to
identify additional studies. Studies that compared methods of functional radiography for quantifying instability in isthmic or degenerative spondylolisthe- sis were included in our study (n = 9). Studies evalu- ating instability in diagnoses other than isthmic and degenerative spondylolisthesis were excluded from direct comparison; however, studies discussing other forms of instability, such as retrolisthesis, are men- tioned in the Discussion where relevant.
For each of the nine studies addressing function- al radiographic techniques in the examination of pa- tients with isthmic spondylolisthesis or patients with degenerative spondylolisthesis, study population size, subject characteristics, diagnosis, subject posi- tioning, instability criteria, and results were collect- ed. These findings were then incorporated into ta- bles and are summarized in the Results section. The validity of each study’s results was judged on the basis of the strength of evidence as determined by study design and study methods including prospec- tive versus retrospective design, sampling method, baseline subject characteristics, quality of methods description, blinding, reproducibility, and power. Because of a paucity of studies evaluating certain methods of functional radiography in the context of spondylolisthesis, we included information about studies that investigated other types of vertebral in- stability in the Discussion section.
Results Table 1 summarizes the nine studies that
investigated methods of functional radiogra- phy in patients with isthmic and degenerative spondylolisthesis. The studies summarized in Table 1 were selected because they present ev- idence for and against alternatives to standing flexion-extension radiography. On average, study size was small, and subject populations were a mixture of patients with isthmic spon- dylolisthesis and patients with degenerative spondylolisthesis. The mean age of the sub- jects in the studies in Table 1 varies consid- erably given the mixture of isthmic and de- generative spondylolisthesis, ranging from a mean age of 32 [54] to 70.1 [46] years. In one study, the lower limit of the age range was 14 years [57]. Only three of nine studies had a control group of asymptomatic healthy sub- jects. The threshold for significant or patho- logic intervertebral slippage used for the stud- ies varied from more than 1.6 mm [58] to more than 5 mm [57].
Studies have experimented with various subject-positioning schemes with the intent of maximizing the sensitivity for detecting lumbar instability on lateral radiographs. Images of the various subject-positioning schemes, which attempt to maximize trans-
lational movement, are shown in Figure 1. Subject positioning is chosen to maximize translational motion of the unstable vertebra. Commonly studied combinations are neutral standing (Fig. 1A) versus neutral recumbent (Fig. 1B), standing flexion (Fig. 1C) versus standing extension (Fig. 1C), lateral decubi- tus flexion (Fig. 1D) versus lateral decubitus extension (Fig. 1E), and hanging axial trac- tion (Fig. 1F) versus standing axial compres- sion [46, 47, 49, 51, 54–58] (Fig. 1G). No single study in Table 1 compares all of the available functional radiographic positions, although the study by Luk et al. [49] comes the closest. Axial traction in these studies is typically produced by having the subject hang from a horizontal bar [55]. Compres- sion has been accomplished by placing a bal- anced weight across the shoulders. Friberg [55, 57] applied an arbitrary 20-kg weight in 1987 and 20–100 kg in 1989. Kälebo et al. [54, 58] also used a 20-kg weight for axial compression in two studies.
D’Andrea et al. [47] is alone in promotion of a modified prone position in which the subject rests on the knees and elbows for a minimum of 5 minutes before a lateral radio- graph of the lumbar spine is obtained (Fig. 1H). The inclusion of a time component is novel but is not comparable because other studies have not specified time as a variable.
Pitkänen et al. [50] studied 306 subjects with suspected lumbar spinal instability using hanging axial traction and standing axial com- pression for patient positioning. In that study, the arbitrary 20-kg compression weight was re- placed with a weight equal to 30% of the sub- ject’s body weight. Pitkänen et al. [50] reported that flexion-extension positioning more fre- quently revealed signs of instability on radiog- raphy than traction-compression positioning, a finding that contradicted the results of Friberg [55, 57] and Kälebo et al. [54, 58].
In the study by Luk et al. [49], the tor- sos of subjects were strapped to a table in the prone (Fig. 1I) and supine (Fig. 1J) po- sitions while traction was applied to the legs. Luk et al. contended that subjects with symptomatic spondylolisthesis will not tol- erate hanging and that the average subject’s grip may not be sufficient to suspend him or her. Stripp [59] publicized the use of later- al flexion-extension lumbar radiographs ob- tained with the patient in a seated position. Although this method has seen limited atten- tion in comparative studies, it does provide an easy, more physiologically friendly option for patients. Putto and Tallroth [53] provide
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
AJR:204, April 2015 W463
Functional Radiography of Spondylolisthesis
a detailed analysis of this method; however, they chose to exclude subjects with any form of spondylolisthesis. The findings of Luk et al. suggest that visualization of maximum dynamic instability does not require hanging
but, rather, requires a combination of stand- ing flexion and prone axial traction to pro- duce maximum dynamic translation.
Wood et al. [51] found the degree of sagit- tal translation to be greater on lateral decu-
bitus flexion-extension radiographs than on standing flexion-extension radiographs.
A methodologic analysis of the studies summarized in Table 1 is shown in Table 2. As shown in Table 2, none of the nine studies
TABLE 1: Studies Comparing Functional Radiographic Methods for Grading Spondylolisthesis (SP)
First Author (Year)
(Diagnosis)
No. of Control Group
50 50 (SP or bilateral PI defects)
Yes NA NR Dynamic translation > 2 mm
NSNR, SFE 26% of patients showed > 2 mm translation from recumbent to standing position; SFE showed additional displacement in only an unspecified “small percentage” of patients
Friberg (1987) [55]
117 117a (45 isthmic SP, 7 DG SP, 65 RL)
Yes: 32/45 with isthmic SP, 7/7 with DG SP, 52/65 with RL
NA Isthmic SP, 36.8; DG SP, 63.8; RL, 35.8
NR NSNR, HATSAC Maximal anterior displacement was seen during standing axial compression and maximal posterior displacement was seen during hanging axial traction
Kälebo (1989) [54]
Yes NA 32 NR NSNR, SFE, HATSAC
HATSAC produced statistically significant sagittal translation in 11/15 patients; NSNR and SFE produced statistically significant sagittal translation in 5/15 and 3/15 patients, respectively
Friberg (1989) [57]
426 NR (range, 14–80)
Dynamic translation > 5 mm
HATSAC HATSAC showed translation of > 5 mm in 45/93 SP patients, 14/14 DG SP patients, and 97/214 RL patients
Kälebo (1990) [58]
44 29 (25 grade I isthmic SP, 4 grade II isthmic SP)
Yes 15 35 Dynamic translation > 1.6 mm or > 3.6% adjacent vertebral endplate AP diameter
HATSAC, neutral recumbent
Wood (1994) [51]
60 50 (27 Isthmic or dysplastic SP, 23 DG SP or history of laminectomy)
Yes 10 Isthmic or dysplastic SP, 38.8; DG SP or had laminec- tomy, 58.9
Dynamic translation > 8% adjacent vertebral endplate AP diameter
SFE, lateral decubitus flexion- extension
Lateral decubitus flexion-exten- sion revealed pathologic translation in 87% of patients versus 42% on SFE
Luk (2003) [49]
377 37 (SP) NA NA 53 NR NSNR, neutral prone, SFE, lateral decubitus flexion-exten- sion, supine axial traction and prone axial traction
Standing flexion and prone axial traction showed maximum subluxation (translation) and reduction, respectively
D’Andrea (2005) [47]
75 75 (Low-grade SP [grade I or II later treated with fusion])
Yes NA NR Dynamic translation > 3 mm
Neutral standing, SFE, neutral supine and modified proned
Greater or new SP was observed in 19/75 patients with the supine and modified prone positioning as compared with SFE; all patients with positive findings on flexion-extension radiographs also had positive findings on supine and modified prone radiographs
(Table 1 continues on next page)
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
Study Characteristic Assessed
Lowe (1976) [56]
Friberg (1987) [55]
Kälebo (1989) [54]
Friberg (1989) [57]
Kälebo (1990) [58]
Wood (1994) [51]
Luk (2003) [49]
– + –b –b – + + –c –b
Study population reported in article was described in adequate detaild
– –e –e + + –e + – +
+ + + + + – + + +
All imaging studies were included (i.e., patients with poor-quality imaging studies not excluded)
–b + –b –b –b + – –c –b
Blinded assessment of images – –b + – –b –b –b – –
+ + + + + + + – +
– + + – – + + – +
Study questiong Feasibility Accuracy Accuracy Feasibility Feasibility Accuracy Accuracy Accuracy Accuracy
Level of evidence as defined by USPSTF guidelines [60]
III III III III III III III III III
Spectrum bias NA NA NA + + + NA NA NA
Note—All of the studies shown here were cross-sectional descriptive studies. Minus sign (–) indicates absent, and plus sign (+) indicates present. SP = spondylolisthesis, USPSTF = U.S. Preventive Services Task Force, NA = not applicable because there was no control group.
aUncertain. bThis information was not included in the study article, so we assumed this study characteristic was absent. cExcluded patients who did not undergo surgery. dMinimum requirements of age, sex, clinical presentation, and indications for investigation. eOnly lacking sex information. fDetail was considered adequate if technique was reproducible from study description. gBased on classification proposed by Freedman [89] and further explained in Mol et al. [61].
TABLE 1: Studies Comparing Functional Radiographic Methods for Grading Spondylolisthesis (SP) (continued)
First Author (Year)
(Diagnosis)
No. of Control Group
Cabraja (2011) [46]
100 100 (72 grade I SP, 28 grade II SP, 83 DG SP, 17 isthmic SP)
Yes NA DG SP, 70.1; isthmic SP, 39.5
Dynamic translation > 4 mm or > 8% at L1– L5 or > 6% adjacent vertebral endplate AP diameter at L5–S1
SFE, NSNRe; standing flexion and neutral recumbente
NSNR and standing flexion and neutral recumbent positioning produce greater sagittal translation than SFEf
Note—All of the studies shown here were cross-sectional descriptive studies. Ref. = reference, PI = pars interarticularis, NA = not applicable, NR = not reported, NSNR = neutral standing and neutral recumbent, SFE = standing flexion and standing extension, DG = degenerative, RL = retrolisthesis, HATSAC = hanging axial traction and standing axial compression, AP = anterior-posterior.
aStudy population was 490 patients with low back pain. bStudy population was 1762 patients with low back pain. cAll subjects in study had chronic low back pain. dPatients were asked to rest on their elbows and knees and relax in that position for a minimum of 5 minutes before lateral radiographs were obtained. eNeutral recumbent images in this study were obtained using CT rather than conventional radiography. fIn 11 patients, standing flexion-extension positioning revealed pathologic translation (> 8%) that was missed on NSNR and standing flexion and neutral recumbent positioning.
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
AJR:204, April 2015 W465
Functional Radiography of Spondylolisthesis
attempted to evaluate the clinical value of various functional radiographic methods in the management of actual patients with isth- mic or degenerative spondylolisthesis. The studies in Table 2 were primarily designed to
try new radiographic methods and assess the diagnostic accuracy of those methods. Stud- ies that seek to show the feasibility or diag- nostic accuracy of a new imaging technique typically compare the results of a standard
test with those of the new test in the same subjects. Thus, all of the studies considered in Table 2 are cross-sectional descriptive studies and can be classified as level III evi- dence according to the U.S. Preventive Ser-
A CB
D E F G
H Fig. 1—Various schemes investigated for positioning subjects to maximize translational movement during radiography in assessment of patients with spondylolisthesis. A–C, Neutral standing (A), neutral recumbent (B), and standing flexion and standing extension (C). Green cone indicates orientation of x-ray emitter. D and E, Lateral decubitus flexion (D) and lateral decubitus extension (E). Insets show translational and rotational movements along x-, y-, and z-axes. F, Hanging axial traction. Green cone indicates orientation of x-ray emitter. G, Standing axial compression. Weights from 20 to 100 kg are used. Green cone indicates orientation of x-ray emitter. H, Modified prone described by D’Andrea et al. [47]. I and J, Prone axial traction (I) and supine axial traction (J) described by Luk et al. [49]. Traction is applied to belt around patient’s waist while upper body is held in position by strap around chest.
JI
Câmara et al.
vices Task Force guidelines [60]. Although most studies of diagnostic accuracy can pro- vide sensitivity and specificity data for a new diagnostic test, the ability of a study to pro- vide sensitivity and specificity data is depen- dent on the existence of a so-called “refer- ence standard” reference test for comparison [61].…
gression of slippage is thought to be mini- mal after the age of 16 years [11]. Beutler et al. [13] followed a cohort of subjects with isthmic spondylolisthesis over a period of 45 years and found that slip progression slowed with each decade.
Degenerative spondylolisthesis, although progressive, rarely exceeds grade II [14]. Spur formation, sclerosis, and ossification of ligaments limit the progression of degen- erative spondylolisthesis [15]. Huang et al. [16] found that 20.9% of a cohort of 86 sub- jects had arthrodesis accompanying spondy- lolisthesis. Subjects with spontaneous fusion were, on average, 10 years older than subjects without arthrodesis. Newman [17] noted that spondylolisthesis could occur with an intact neural arch in the presence of facet joint de- generation and may have been the first to call this entity “degenerative spondylolisthesis.”
Meyerding [18] developed a grading sys- tem that measures the amount of slippage as a percentage of the diameter of the verte- bra below the slippage. He defined grade I as 0–25% displacement, grade II as 26–50% displacement, grade III as 51–75% displace- ment, and grade IV as 76-100% displacement, and grade V (spondyloptosis) as greater than 100%. Grades I and II are considered low- grade. Keep in mind that Meyerding’s grad- ing of spondylolisthesis does not necessarily
Functional Radiography in Examination of Spondylolisthesis
Justin R Câmara1
Joseph R. Keen2
Câmara JR, Keen JR, Asgarzadie F
1Loma Linda University, 11234 Anderson St, Loma Linda, CA 92354. Address correspondence to J. R. Câmara ([email protected]).
2Department of Neurological Surgery, Loma Linda University, Loma Linda, CA.
Musculoskeleta l Imaging • Review
AJR 2015; 204:W461–W469
© American Roentgen Ray Society
S pondylolisthesis is the anterior slippage of one vertebra relative to the inferior vertebra [1]. Mul- tiple classification systems have
been proposed for spondylolisthesis [2–5], but commonly used classifications are dys- plastic, isthmic, degenerative, traumatic, and pathologic [1]. Isthmic spondylolisthesis is by definition always accompanied by and is often preceded by spondylolysis, a defect in the pars interarticularis that allows the verte- bral body to slip anteriorly, especially during a growth spurt. The term “spondylolysis” re- fers strictly to defects in the pars interarticu- laris that may or may not be accompanied by vertebral slippage. The slippage in this case would be termed “isthmic spondylolisthesis” [6, 7]. Degenerative spondylolisthesis, on the other hand, occurs in the absence of pars in- terarticularis defects. The entire vertebra in- cluding the arch slips anteriorly relative to the inferior vertebra [8].
Kalichman et al. [9] found that the preva- lence of spondylolysis diagnosed using CT in a community-based population was 11.5%, which is a much higher prevalence than re- ported in previous studies using convention- al radiography. Spondylolysis progresses to isthmic spondylolisthesis in a significant fraction of cases, with reports of progression in up to 80% of cases [10–12]; however, pro-
Keywords: degenerative spondylolisthesis, flexion- extension, functional radiography, instability, isthmic, spondylolisthesis, translation
DOI:10.2214/AJR.14.13139
Received May 14, 2014; accepted after revision July 24, 2014.
OBJECTIVE. Despite the predominant use of standing flexion-extension radiography for quantifying instability in isthmic and degenerative spondylolisthesis, other functional radio- graphic techniques have been presented in the literature.
CONCLUSION. The current evidence reported in the literature is insufficient to influ- ence how the results of these other functional radiographic techniques should affect clinical management; however, it does raise doubts regarding the accuracy and reliability of stand- ing flexion-extension radiography in this setting. Based on the currently available evidence and until randomized studies are performed to assess the efficacy of functional radiographic techniques in directing clinical decision making, positioning schemes other than traditional standing flexion-extension may be considered as options in the evaluation of patients with symptomatic isthmic and degenerative spondylolisthesis in which standard flexion-extension radiographs fail to show pathologic instability.
Câmara et al. Functional Radiography of Spondylolisthesis
Musculoskeletal Imaging Review
Câmara et al.
signify instability [19]. The term “spondylop- tosis” is reserved for 100% displacement of the superior vertebra [20].
The choice of vertebral landmarks used to measure the degree of slippage is debat- able and varies among studies [21–23]. Stand- ing conventional radiographs from the lateral view are often used to identify spondylolis- thesis, whereas standing flexion-extension ra- diographs are commonly used to quantify the degree of intervertebral instability [24–31]. Although not sufficient alone, standing flex- ion-extension radiographs are often used in combination with clinical signs and symptoms to choose between conservative management and surgery—specifically, fusion [32–40]. The relationship between radiographically visible instability and clinical findings is un- clear. Some studies have found that instabil- ity seen on functional radiographs correlates well with symptoms of low back pain [41, 42], whereas other studies have not found this rela- tionship to hold true [24, 43]. Currently, func- tional radiography is most useful when its findings agree with the larger context of clini- cal signs and symptoms [44, 45].
Despite the predominant use of standing flexion-extension radiographs for quantify- ing instability in isthmic and degenerative spondylolisthesis, other forms of functional radiography have been proposed and eval- uated in the literature [24, 29, 46–56]. The purpose of this article is to evaluate the evi- dence for various forms of functional radiog- raphy with potential usefulness in examining instability in patients with isthmic spondylo- listhesis and in those with degenerative spon- dylolisthesis. The term “instability” as used here refers to the acute motion of the verte- brae at the level of spondylolisthesis as a re- sult of external forces such as weight, trac- tion, or a change in body position.
Materials and Methods A search of the PubMed database was performed
for articles published in English through April 2013 that included any of the following terms: spondylo- listhesis intervertebral instability, spondylolisthesis prone radiography, spondylolisthesis supine radiog- raphy, spondylolisthesis traction radiography, spon- dylolisthesis flexion-extension radiography, spondy- lolisthesis instability radiography, spondylolisthesis recumbent radiography, spondylolisthesis dynamic radiography, spondylolisthesis functional radiogra- phy, and spondylolisthesis stress radiography. The search yielded a total of 887 results. Additionally, the related citations generated by PubMed and the bibliographies of relevant articles were checked to
identify additional studies. Studies that compared methods of functional radiography for quantifying instability in isthmic or degenerative spondylolisthe- sis were included in our study (n = 9). Studies evalu- ating instability in diagnoses other than isthmic and degenerative spondylolisthesis were excluded from direct comparison; however, studies discussing other forms of instability, such as retrolisthesis, are men- tioned in the Discussion where relevant.
For each of the nine studies addressing function- al radiographic techniques in the examination of pa- tients with isthmic spondylolisthesis or patients with degenerative spondylolisthesis, study population size, subject characteristics, diagnosis, subject posi- tioning, instability criteria, and results were collect- ed. These findings were then incorporated into ta- bles and are summarized in the Results section. The validity of each study’s results was judged on the basis of the strength of evidence as determined by study design and study methods including prospec- tive versus retrospective design, sampling method, baseline subject characteristics, quality of methods description, blinding, reproducibility, and power. Because of a paucity of studies evaluating certain methods of functional radiography in the context of spondylolisthesis, we included information about studies that investigated other types of vertebral in- stability in the Discussion section.
Results Table 1 summarizes the nine studies that
investigated methods of functional radiogra- phy in patients with isthmic and degenerative spondylolisthesis. The studies summarized in Table 1 were selected because they present ev- idence for and against alternatives to standing flexion-extension radiography. On average, study size was small, and subject populations were a mixture of patients with isthmic spon- dylolisthesis and patients with degenerative spondylolisthesis. The mean age of the sub- jects in the studies in Table 1 varies consid- erably given the mixture of isthmic and de- generative spondylolisthesis, ranging from a mean age of 32 [54] to 70.1 [46] years. In one study, the lower limit of the age range was 14 years [57]. Only three of nine studies had a control group of asymptomatic healthy sub- jects. The threshold for significant or patho- logic intervertebral slippage used for the stud- ies varied from more than 1.6 mm [58] to more than 5 mm [57].
Studies have experimented with various subject-positioning schemes with the intent of maximizing the sensitivity for detecting lumbar instability on lateral radiographs. Images of the various subject-positioning schemes, which attempt to maximize trans-
lational movement, are shown in Figure 1. Subject positioning is chosen to maximize translational motion of the unstable vertebra. Commonly studied combinations are neutral standing (Fig. 1A) versus neutral recumbent (Fig. 1B), standing flexion (Fig. 1C) versus standing extension (Fig. 1C), lateral decubi- tus flexion (Fig. 1D) versus lateral decubitus extension (Fig. 1E), and hanging axial trac- tion (Fig. 1F) versus standing axial compres- sion [46, 47, 49, 51, 54–58] (Fig. 1G). No single study in Table 1 compares all of the available functional radiographic positions, although the study by Luk et al. [49] comes the closest. Axial traction in these studies is typically produced by having the subject hang from a horizontal bar [55]. Compres- sion has been accomplished by placing a bal- anced weight across the shoulders. Friberg [55, 57] applied an arbitrary 20-kg weight in 1987 and 20–100 kg in 1989. Kälebo et al. [54, 58] also used a 20-kg weight for axial compression in two studies.
D’Andrea et al. [47] is alone in promotion of a modified prone position in which the subject rests on the knees and elbows for a minimum of 5 minutes before a lateral radio- graph of the lumbar spine is obtained (Fig. 1H). The inclusion of a time component is novel but is not comparable because other studies have not specified time as a variable.
Pitkänen et al. [50] studied 306 subjects with suspected lumbar spinal instability using hanging axial traction and standing axial com- pression for patient positioning. In that study, the arbitrary 20-kg compression weight was re- placed with a weight equal to 30% of the sub- ject’s body weight. Pitkänen et al. [50] reported that flexion-extension positioning more fre- quently revealed signs of instability on radiog- raphy than traction-compression positioning, a finding that contradicted the results of Friberg [55, 57] and Kälebo et al. [54, 58].
In the study by Luk et al. [49], the tor- sos of subjects were strapped to a table in the prone (Fig. 1I) and supine (Fig. 1J) po- sitions while traction was applied to the legs. Luk et al. contended that subjects with symptomatic spondylolisthesis will not tol- erate hanging and that the average subject’s grip may not be sufficient to suspend him or her. Stripp [59] publicized the use of later- al flexion-extension lumbar radiographs ob- tained with the patient in a seated position. Although this method has seen limited atten- tion in comparative studies, it does provide an easy, more physiologically friendly option for patients. Putto and Tallroth [53] provide
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
AJR:204, April 2015 W463
Functional Radiography of Spondylolisthesis
a detailed analysis of this method; however, they chose to exclude subjects with any form of spondylolisthesis. The findings of Luk et al. suggest that visualization of maximum dynamic instability does not require hanging
but, rather, requires a combination of stand- ing flexion and prone axial traction to pro- duce maximum dynamic translation.
Wood et al. [51] found the degree of sagit- tal translation to be greater on lateral decu-
bitus flexion-extension radiographs than on standing flexion-extension radiographs.
A methodologic analysis of the studies summarized in Table 1 is shown in Table 2. As shown in Table 2, none of the nine studies
TABLE 1: Studies Comparing Functional Radiographic Methods for Grading Spondylolisthesis (SP)
First Author (Year)
(Diagnosis)
No. of Control Group
50 50 (SP or bilateral PI defects)
Yes NA NR Dynamic translation > 2 mm
NSNR, SFE 26% of patients showed > 2 mm translation from recumbent to standing position; SFE showed additional displacement in only an unspecified “small percentage” of patients
Friberg (1987) [55]
117 117a (45 isthmic SP, 7 DG SP, 65 RL)
Yes: 32/45 with isthmic SP, 7/7 with DG SP, 52/65 with RL
NA Isthmic SP, 36.8; DG SP, 63.8; RL, 35.8
NR NSNR, HATSAC Maximal anterior displacement was seen during standing axial compression and maximal posterior displacement was seen during hanging axial traction
Kälebo (1989) [54]
Yes NA 32 NR NSNR, SFE, HATSAC
HATSAC produced statistically significant sagittal translation in 11/15 patients; NSNR and SFE produced statistically significant sagittal translation in 5/15 and 3/15 patients, respectively
Friberg (1989) [57]
426 NR (range, 14–80)
Dynamic translation > 5 mm
HATSAC HATSAC showed translation of > 5 mm in 45/93 SP patients, 14/14 DG SP patients, and 97/214 RL patients
Kälebo (1990) [58]
44 29 (25 grade I isthmic SP, 4 grade II isthmic SP)
Yes 15 35 Dynamic translation > 1.6 mm or > 3.6% adjacent vertebral endplate AP diameter
HATSAC, neutral recumbent
Wood (1994) [51]
60 50 (27 Isthmic or dysplastic SP, 23 DG SP or history of laminectomy)
Yes 10 Isthmic or dysplastic SP, 38.8; DG SP or had laminec- tomy, 58.9
Dynamic translation > 8% adjacent vertebral endplate AP diameter
SFE, lateral decubitus flexion- extension
Lateral decubitus flexion-exten- sion revealed pathologic translation in 87% of patients versus 42% on SFE
Luk (2003) [49]
377 37 (SP) NA NA 53 NR NSNR, neutral prone, SFE, lateral decubitus flexion-exten- sion, supine axial traction and prone axial traction
Standing flexion and prone axial traction showed maximum subluxation (translation) and reduction, respectively
D’Andrea (2005) [47]
75 75 (Low-grade SP [grade I or II later treated with fusion])
Yes NA NR Dynamic translation > 3 mm
Neutral standing, SFE, neutral supine and modified proned
Greater or new SP was observed in 19/75 patients with the supine and modified prone positioning as compared with SFE; all patients with positive findings on flexion-extension radiographs also had positive findings on supine and modified prone radiographs
(Table 1 continues on next page)
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
Study Characteristic Assessed
Lowe (1976) [56]
Friberg (1987) [55]
Kälebo (1989) [54]
Friberg (1989) [57]
Kälebo (1990) [58]
Wood (1994) [51]
Luk (2003) [49]
– + –b –b – + + –c –b
Study population reported in article was described in adequate detaild
– –e –e + + –e + – +
+ + + + + – + + +
All imaging studies were included (i.e., patients with poor-quality imaging studies not excluded)
–b + –b –b –b + – –c –b
Blinded assessment of images – –b + – –b –b –b – –
+ + + + + + + – +
– + + – – + + – +
Study questiong Feasibility Accuracy Accuracy Feasibility Feasibility Accuracy Accuracy Accuracy Accuracy
Level of evidence as defined by USPSTF guidelines [60]
III III III III III III III III III
Spectrum bias NA NA NA + + + NA NA NA
Note—All of the studies shown here were cross-sectional descriptive studies. Minus sign (–) indicates absent, and plus sign (+) indicates present. SP = spondylolisthesis, USPSTF = U.S. Preventive Services Task Force, NA = not applicable because there was no control group.
aUncertain. bThis information was not included in the study article, so we assumed this study characteristic was absent. cExcluded patients who did not undergo surgery. dMinimum requirements of age, sex, clinical presentation, and indications for investigation. eOnly lacking sex information. fDetail was considered adequate if technique was reproducible from study description. gBased on classification proposed by Freedman [89] and further explained in Mol et al. [61].
TABLE 1: Studies Comparing Functional Radiographic Methods for Grading Spondylolisthesis (SP) (continued)
First Author (Year)
(Diagnosis)
No. of Control Group
Cabraja (2011) [46]
100 100 (72 grade I SP, 28 grade II SP, 83 DG SP, 17 isthmic SP)
Yes NA DG SP, 70.1; isthmic SP, 39.5
Dynamic translation > 4 mm or > 8% at L1– L5 or > 6% adjacent vertebral endplate AP diameter at L5–S1
SFE, NSNRe; standing flexion and neutral recumbente
NSNR and standing flexion and neutral recumbent positioning produce greater sagittal translation than SFEf
Note—All of the studies shown here were cross-sectional descriptive studies. Ref. = reference, PI = pars interarticularis, NA = not applicable, NR = not reported, NSNR = neutral standing and neutral recumbent, SFE = standing flexion and standing extension, DG = degenerative, RL = retrolisthesis, HATSAC = hanging axial traction and standing axial compression, AP = anterior-posterior.
aStudy population was 490 patients with low back pain. bStudy population was 1762 patients with low back pain. cAll subjects in study had chronic low back pain. dPatients were asked to rest on their elbows and knees and relax in that position for a minimum of 5 minutes before lateral radiographs were obtained. eNeutral recumbent images in this study were obtained using CT rather than conventional radiography. fIn 11 patients, standing flexion-extension positioning revealed pathologic translation (> 8%) that was missed on NSNR and standing flexion and neutral recumbent positioning.
D ow
nl oa
de d
fr om
w w
w .a
jr on
lin e.
or g
by 1
17 .3
.2 52
.4 o
n 04
/1 3/
23 f
ro m
I P
ad dr
es s
11 7.
3. 25
2. 4.
C op
yr ig
ht A
R R
S. F
or p
er so
AJR:204, April 2015 W465
Functional Radiography of Spondylolisthesis
attempted to evaluate the clinical value of various functional radiographic methods in the management of actual patients with isth- mic or degenerative spondylolisthesis. The studies in Table 2 were primarily designed to
try new radiographic methods and assess the diagnostic accuracy of those methods. Stud- ies that seek to show the feasibility or diag- nostic accuracy of a new imaging technique typically compare the results of a standard
test with those of the new test in the same subjects. Thus, all of the studies considered in Table 2 are cross-sectional descriptive studies and can be classified as level III evi- dence according to the U.S. Preventive Ser-
A CB
D E F G
H Fig. 1—Various schemes investigated for positioning subjects to maximize translational movement during radiography in assessment of patients with spondylolisthesis. A–C, Neutral standing (A), neutral recumbent (B), and standing flexion and standing extension (C). Green cone indicates orientation of x-ray emitter. D and E, Lateral decubitus flexion (D) and lateral decubitus extension (E). Insets show translational and rotational movements along x-, y-, and z-axes. F, Hanging axial traction. Green cone indicates orientation of x-ray emitter. G, Standing axial compression. Weights from 20 to 100 kg are used. Green cone indicates orientation of x-ray emitter. H, Modified prone described by D’Andrea et al. [47]. I and J, Prone axial traction (I) and supine axial traction (J) described by Luk et al. [49]. Traction is applied to belt around patient’s waist while upper body is held in position by strap around chest.
JI
Câmara et al.
vices Task Force guidelines [60]. Although most studies of diagnostic accuracy can pro- vide sensitivity and specificity data for a new diagnostic test, the ability of a study to pro- vide sensitivity and specificity data is depen- dent on the existence of a so-called “refer- ence standard” reference test for comparison [61].…
Related Documents
