Effectiveness of an Extension-Oriented Treatment Approach in a Subgroup of Subjects With Low Back...

8/6/2019 Effectiveness of an Extension-Oriented Treatment Approach in a Subgroup of Subjects With Low Back Pain

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Effectiveness of an Extension-OrientedTreatment Approach in a Subgroupof Subjects With Low Back Pain:A Randomized Clinical TrialDavid A Browder, John D Childs, Joshua A Cleland, Julie M Fritz

Background and PurposeThe purpose of this multicenter randomized clinical trial was to examine the effec-

tiveness of an extension-oriented treatment approach (EOTA) in a subgroup ofsubjects with low back pain (LBP) who were hypothesized to benefit from thetreatment compared with similar subjects who received a lumbar spine strengtheningexercise program.

MethodsSubjects with LBP and symptoms distal to the buttocks that centralized with exten-sion movements were included. Forty-eight subjects were randomly assigned togroups that received an EOTA (n26) or a strengthening exercise program (n22).

Subjects attended 8 physical therapy sessions and completed a home exercise pro-gram. Follow-up data were obtained at 1 week, 4 weeks, and 6 months afterrandomization. Primary outcome measures were disability (modified Oswestry Low

Back Pain Disability Questionnaire) and pain (Numeric Pain Rating Scale).

ResultsSubjects in the EOTA group experienced greater improvements in disability com-

pared with subjects who received trunk strengthening exercises at 1 week (meandifference between groups from baseline8.9, 95% confidence interval [CI]2.0,15.9), 4 weeks, (mean difference14.4, 95% CI4.8, 23.9), and 6 months (meandifference14.6, 95% CI4.6, 24.6). The EOTA group demonstrated greater changein pain at the 1-week follow-up only.

Discussion and ConclusionAn EOTA was more effective than trunk strengthening exercise in a subgroup of

subjects hypothesized to benefit from this treatment approach. Additional research isneeded to explore whether an EOTA may benefit other subgroups of patients.

DA Browder, MAJ, PT, DPT, OCS,is Director, Outpatient PhysicalTherapy, Physical Therapy Depart-ment, Wilford Hall Medical Cen-

ter, San Antonio, Tex, and Assis-tant Professor, US ArmyBaylorUniversity Doctoral Program inPhysical Therapy, San Antonio,Tex. Institutional address: 59CSG/59 DTS/SGOYP, 2200Bergquist Dr, Ste 1, Lackland AFB,TX 78154 (USA). Address all cor-respondence to Dr Browder at:[email protected].

JD Childs, PT, PhD, MBA, OCS,FAAOMPT, is Assistant Professorand Director of Research, US

ArmyBaylor University DoctoralProgram in Physical Therapy.

JA Cleland, PT, PhD, OCS,FAAOMPT, is Associate Professor,Franklin Pierce University, Con-cord, NH, and Physical Therapist,Rehabilitation Services, ConcordHospital, Concord, NH.

JM Fritz, PT,PhD, ATC, is AssociateProfessor, Division of PhysicalTherapy, University of Utah, andClinical Outcomes Research Scien-tist, Intermountain Healthcare,Salt Lake City, Utah.

[Browder DA, Childs JD, ClelandJA, Fritz JM. Effectiveness of anextension-oriented treatment ap-proach in a subgroup of subjectswith low back pain: a randomizedclinical trial. Phys Ther. 2007;87:16081618.]

2007 American Physical TherapyAssociation

Research Report

Post a Rapid Response orfind The Bottom Line:www.ptjournal.org

1608 f Physical Therapy Volume 87 Number 12 December 2007


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Next to the common cold, lowback pain (LBP) is the mostcommon reason individuals

visit a physicians office,1 resulting inbillions of dollars in medical expen-

ditures and lost labor costs eachyear.2 Attempts to identify effectivenonsurgical treatment approachessuch as exercise for the managementof LBP have been largely unsuccess-ful,3 resulting in a array of disparatetreatment recommendations in LBP

practice guidelines.4

The equivocal findings on the effec-tiveness of exercise for LBP may beattributable to the failure of research-ers to adequately account for the im-

portance of subgrouping, or classify-ing, subjects.5 The use of broadinclusion criteria in previous re-

search may result in the selection ofheterogeneous samples that likely in-clude many subjects for whom nobenefit is expected from the partic-ular treatment, thus potentiallymasking the interventions true

value. Consequently, the develop-ment of methods for identifying sub-groups of subjects with LBP and

matching them to the treatmentsmost likely to benefit them hasevolved as an important researchpriority.57

One subgroup of subjects with LBPconsists of subjects proposed to ben-efit from an extension-oriented treat-ment approach (EOTA). This ap-

proach typically involves somecombination of active or passive ac-tivities to promote extension in thelumbar spine.8,9 Several studies haveexamined the effectiveness of anEOTA for subjects with LBP, withmost finding no benefit compared

with other treatments1017; how-ever, these studies have not sought

to identify subjects a priori whomight be likely to respond to anEOTA, leaving open the possibilitythat a subgroup of patients with LBPmay exist for whom EOTA is a ben-eficial treatment.

Several recent studies1821 have provided preliminary evidence that theuse of subgrouping classification

methods for the physical therapistmanagement of subjects with LBP

may result in better outcomes thanphysical therapist management thatis not classification based. Thetreatment-based classification systemdescribed by Delitto and colleagues8

includes a subgroup of subjectsthought to preferentially benefit

from an EOTA. The key criterion forinclusion in the EOTA subgroup isthe presence of the centralizationphenomenon with extension move-ment testing during the physicalexamination.18,22 Other authori-

ties9,23,24 also have proposed thatcentralization is important in identi-fying patients likely to benefit from

an EOTA.

The centralization phenomenon oc-curs when a movement or positionresults in the migration of symptomsfrom an area more distal or lateral inthe buttocks or lower extremity to alocation more proximal or closer tothe midline of the lumbar spine.9 Al-

though it is generally agreed that pa-tients likely to benefit from an EOTAare those who experience centraliza-tion with lumbar extension move-ments, most previous studies havenot incorporated this hypothesisinto their design or inclusion criteria.The purpose of this study was toexamine the effectiveness of an

EOTA in a subgroup of subjects hy-pothesized to benefit from the treat-ment compared with a lumbar spinestrengthening exercise program atboth short-term and long-termfollow-up.

MethodConsecutive patients who were re-

ceiving physical therapy interven-tion for a primary complaint of LBP

were considered for participation.Ten physical therapists at 9 clinics in

various settings in the United States(3 academic medical centers and 6

smaller outpatient practice settings)participated. The median age of theparticipating physical therapists was

37 years (range3040 years), withan average of 7 years of practice

(range

116 years) in an outpatientorthopedic setting. Most participat-ing sites were health care facilities

within the Department of Defensethat treated active-duty and retiredpersonnel as well as dependent fam-ily members. Each sites institutional

review board approved the study be-fore recruitment began.

Inclusion criteria were age between18 and 60 years, with LBP and symp-toms of any duration extending distal

to the buttocks on at least one lowerextremity. The centralization phe-nomenon, determined by the exam-

iner using active movement testing,had to be present. A single move-ment of lumbar extension was as-sessed first, followed by repeated ex-tension movements consisting of 10repetitions performed with the sub-

ject standing. Repeated extensionmovements also were performed

with the subject positioned prone.

Centralization was judged to bepresent when extension movementabolished symptoms or caused symp-toms to move proximally toward themidline of the lumbar spine in atleast one of these positions. The in-terrater reliability of determining thepresence of centralization using thisdefinition has been reported to be

high.22 A modified Oswestry LowBack Pain Disability Questionnaire(ODQ) score of at least 30% was re-quired. Exclusion criteria were redflags possibly indicative of a patho-logical condition (eg, tumor, frac-ture, infection), current pregnancy,or surgery to the lumbar spine in thepast 6 months. Once admitted, we

used intention-to-treat principles, with no subject removed fornonadherence.

An Extension-Oriented Treatment Approach to Low Back Pain

December 2007 Volume 87 Number 12 Physical Therapy f 1609


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History and Physical ExaminationAt baseline, subjects completed sev-eral self-report measures and then re-

ceived a standardized history andphysical examination. Baseline as-

sessments were performed by aphysical therapist who was unawareof the subjects treatment group. There-examinations were not alwaysconducted by an examiner who wasunaware of the subjects treatmentgroup; however, the re-examination

procedures consisted of self-reportquestionnaires that were completedby the subjects without any input orinfluence from the examiner.

Self-report measures included the

ODQ, Numeric Pain Rating Scale(NPRS), and Fear-Avoidance BeliefsQuestionnaire (FABQ). The ODQ is a

region-specific disability scale for pa-tients with LBP, with scores rangingfrom 0 to 100, that has been shownto exhibit high levels of reliability,

validity, and responsiveness.25 TheNPRS is an 11-point pain rating scaleranging from 0 (no pain) to 10(worst pain imaginable), which wasused to assess current pain intensity

and the best and worst level of painduring the last 24 hours.26 The 3scores were averaged. The FABQ

was used to quantify the subjectsfear of pain and beliefs about avoid-ing activity.27 Subjects also recordedthe anatomic location of symptomson a body diagram. The body dia-gram was used to determine the

extent to which centralization oc-curred at follow-up visits. Symptomlocation was recorded using proce-dures shown to have excellent reli-ability.24 The most distal symptoms

were scored as: 0 if no symptomswere identified, 1 if the most distalsymptoms were in the central lowback, 2 in the lateral low back, 3 in

the buttocks, 4 in the thigh, 5 in thecalf, or 6 in the foot. Figure 1 showsthe demarcations for each area forbody chart scoring.

The history consisted of demo-graphic information, including age;sex; height; weight; past medical his-tory; duration, location, and natureof symptoms; relieving and aggravat-ing activities; prior episodes of LBP;occupation; and participation in lei-sure activities. Physical examinationprocedures included a neurologicalassessment of strength (muscle

force-generating capacity), sensa-tion, muscle-stretch reflexes, andstraight leg raise test; measurementsof active lumbar range of motion us-ing a single inclinometer28; andposterior-to-anterior mobility of thelumbar spine performed with thesubjects positioned prone.29

Therapist TrainingEach participating physical therapistreceived a detailed manual of oper-ating procedures defining all exami-nation and treatment techniques

used in the study. Each therapist alsomet with an investigator before datacollection began to ensure proper

performance of all examination andtreatment procedures.

Treatment Groups A random number generator wasused to construct a randomizationlist prior to the study. Individual, se-quentially numbered index cards

with the randomization assignments

were prepared. The index cardswere folded and placed in sealed en-velopes. After the baseline examina-tion, the physical therapist who con-ducted the examination opened theenvelope, indicating the treatment

group assignment. Subjects wererandomly assigned to 1 of 2 exercisegroups: (1) the EOTA group or (2)

the strengthening group. Subjects inboth groups attended physical ther-apy sessions twice a week for thefirst 2 weeks, then once a week forthe next 2 weeks, for a total of 6sessions over 4 weeks.

Treatment was initiated immediatelyafter completion of the baseline ex-

amination unless prohibited by timeconstraints, in which case the firsttreatment session took place within48 hours of the baseline examina-tion. All subjects were provided acopy of an exercise instruction book-let with detailed written descriptionsand pictures of the proper perfor-mance, frequency, and progression

of each exercise (Supplemental Ap-pendixes 1 and 2 available onlineonly at www.ptjournal.org). Sub-

jects were instructed to record theiradherence in an exercise log, which

was reviewed by the treating thera-pist at each session to encourage ad-herence. Subjects were instructed toperform their assigned exercise pro-

gram at home on the days that theydid not attend physical therapy ses-sions. On the basis of the benefitsassociated with remaining active,30

subjects in both groups also were

Figure 1.Body chart for symptom location analysis.




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given advice to maintain their usualactivity within the limits of pain.

EOTA group. Subjects in theEOTA group received exercise and

mobilization to promote extensionof the lumbar spine with the goal ofproducing centralization of symp-toms. The first activity consisted of aseries of extension-oriented exer-cises, including sustained and re-peated lumbar extension in prone

and standing positions. Extension ex-ercises were progressed as toleratedstarting with static prone positioningand progressing to repeated end-range prone and standing extension.

A subject who tolerated the com-

plete exercise program performed 3sets of 10 repetitions of repeatedend-range extension in prone posi-

tion and then 3 sets of 10 repetitionsof end-range extension in standing,holding each repetition at end rangefor 2 to 3 seconds (Supplemental

Appendix 1).

The second activity to promote lum-bar extension was posterior-to-anterior lumbar mobilization. The

mobilization technique consisted ofa series of 10 to 20 grade I to IVoscillations based on the proceduresdescribed by Maitland.31 The thera-pist selected the grade and segmen-tal level at which the mobilization

was directed during each treatmentsession based on the considerationof several factors, including the goal

of achieving maximum centraliza-tion, reducing segmental hypomobil-ity, and decreasing symptoms.

In addition to the mobilization treat-ment and exercise program in theclinic, subjects were instructed toperform 1 set of 10 repetitions of theprone press-up exercise every 2 to 3

waking hours during the 4-weektreatment period. Alternatively, theycould perform 1 set of 10 repetitionsof repeated extension in standing ifthey were unable to assume theprone position (eg, at work, out

shopping). Therapists also providededucation on how to maintain thenatural lordosis of the lumbar spine

while sitting, and subjects were in-structed to avoid sitting for periods

greater than 20 to 30 minutes. Inaddition, subjects were given gen-eral instructions to discontinue anyactivities and avoid positions thatcaused their symptoms to peripher-alize or that led to an increase in theintensity of their symptoms. Alterna-

tively, subjects were encouraged toperform activities and maintain posi-tions that centralized or improvedtheir symptoms.

Strengthening group. System-

atic reviews recommend musclestrengthening exercises for patients

with chronic LBP.32 This study used

a strengthening program designedby Hicks et al33 to improve isolatedcontractions of the deep abdominalmuscles (eg, transversus abdominus)and to strengthen primary stabilizersof the spine (eg, oblique abdominal,multifidus, quadratus lumborum,and erector spinae muscles).34,35 Theprogram is described in detail in Sup-

plemental Appendix 2. Subjects per-formed the strengthening exerciseprogram in the physical therapyclinic and were instructed to per-form the program at home once dailyon days they did not attend physicaltherapy sessions.

To balance possible attention effects

between treatment groups, thera-pists closely supervised subjects per-forming strengthening exercises andprovided frequent verbal encourage-ment and tactile cues while instruct-ing the subjects in the exercises. Al-though this program was performedonly once a day, compared with ahome program performed several

times a day by the subjects receivingan EOTA, the strengthening programrequired more time to complete,making the total amount of daily ex-ercise time comparable betweengroups.

Follow-up ExaminationsFollow-up examinations were per-formed 1 and 4 weeks after random-

ization. Follow-up examinationsincluded re-assessment of the self-

report measures. At approximately 6months after discharge, the self-report questionnaires were mailedalong with a questionnaire concern-ing additional interventions that thesubjects may have received follow-ing completion of the study. If sub-

jects did not respond to the initialfollow-up mailing, multiple attempts

were made to contact each subjectto ensure that they received and hadthe opportunity to respond to thequestionnaire.

Sample Size CalculationSample size calculations were based

on detecting a 10-point difference onthe ODQ, which has been identifiedas the minimum clinically importantdifference.36A sample size of 24 sub-

jects per group provided 80% powerto detect a clinically important differ-ence of 10 points between groups,assuming a common standard devia-tion of 12.0 and a 2-sided hypothesis

with an alpha level of .05.

Data AnalysisBaseline variables were comparedbetween groups using independent ttests or Mann-Whitney U tests forcontinuous data or chi-square testsof independence for categoricaldata. Potential differences in the

follow-up rate were examined usinga Pearson chi-square test. The effectsof treatment on pain and disability

were examined with 2-way repeated-measures analysis of covariance(ANCOVA), with treatment group(EOTA versus strengthening) as thebetween-subjects variable and time(baseline and follow-up) as the

within-subjects variable. The use ofan ANCOVA was not preplanned,and the use of the planned analysisthat did not adjust for previous sur-gery provides a different result. His-tory of lumbar surgery was used as a




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covariate because previous lumbarsurgery may adversely affect progno-

sis,37,38 and it differed betweengroups. Separate ANCOVAs wereperformed with pain (NPRS) and dis-ability (ODQ) as the dependent vari-able. For each ANCOVA, the hypoth-esis of interest was the 2-way

interaction between time and group.We hypothesized that subjects in the

EOTA group would experiencegreater improvement in pain and dis-ability at each follow-up compared

with subjects in the strengtheninggroup. We also performed plannedpair-wise comparisons to examine

differences from baseline to eachtime point separately between thetreatment groups.

The effect of treatment on location

of symptoms was examined by com-paring the proportion of patients ineach group whose symptoms cen-tralized at the 1- and 4-weekfollow-up assessments. At eachfollow-up, the subjects symptoms

were categorized using a body chart

(Fig. 1) as central (symptoms abol-ished or in only area 1 on the bodychart) or non-central (symptomspresent in area 2 or more distal onthe body chart). We also categorizedsubjects as improved (symptoms

moved more proximal than baselinelocation) or not improved (symp-toms moved more distal or unmoved

from baseline). We hypothesizedthat a greater proportion of subjectsin the EOTA group would have cen-tral symptoms and experienceimprovement at 1 and 4 weeks.Intention-to-treat principles wereused to account for subjects whodropped out by carrying the lastavailable score forward.

Results Approximately 300 patients werescreened for eligibility during a 22-month period from March 2003 toDecember 2004; 63 patients satisfiedthe criteria for inclusion in the study.The high rate of ineligibility is attrib-utable to our effort to identify a sub-

group of subjects most likely to ben-efit from an EOTA, namely thosesubjects with LBP whose symptomsextend below the buttocks and whodemonstrate centralization of symp-toms with extension movementsupon initial examination. Fifteen eli-gible subjects declined to partici-pate: 5 for no particular reason and

10 due to time constraints. The re-maining 48 subjects (mean age39.0

years, SD10.2; 31% female), wererandomly assigned to the EOTAgroup (n26) or to the strengthen-ing group (n22). Figure 2 illus-

Subjects with low back pain who met inclusion or exclusioncriteria (n=63)

Elected not to participate

(n=15)

Baseline examination and randomization (n=48)

Strengthening group (n=22)EOTA group (n=26)

1-wk follow-up (n=26)

Total lost to follow-up (n=0)

Discontinued intervention (n=0)


Total lost to follow-up (n=0)

Discontinued intervention (n=1,[4.5%], increased pain)


Total lost to follow-up (n=1, [4.5%],

did not return telephone calls)


Total lost to follow-up (n=1, [4.0%],did not return telephone calls)

6-mo follow-up (n=15)

Total lost to follow-up (n=11, [42%])

*Did not return 6-mo follow-up

questionnaire after 2telephone reminders: 4

*Unable to return due to

deployment: 4*Mail returned undeliverable

and contact information nolonger current: 3

6-mo follow-up (n=16)

Total lost to follow-up (n=6, [27%])

*Did not return 6-mo follow-up

questionnaire after 2telephone reminders: 3

*Unable to return due to

deployment: 2*Mail returned undeliverable

and contact information nolonger current: 1

Figure 2.Flow diagram for subject recruitment and randomization. EOTAextension-orientedtreatment approach.




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trates the flow diagram for subjectrecruitment, randomization, andretention.

Baseline variables for each group arepresented in Table 1. A notable dif-ference between groups was the his-tory of lumbar surgery (Tab. 1). Fivesubjects in the EOTA group reported

a history of lumbar surgery com-pared with no subjects in thestrengthening group. Patients with arecent history of surgery (within thepast 6 months) were excluded fromthe study, but patients with a pasthistory of surgery met the inclusioncriteria.

Results of the repeated-measures ANCOVA showed a significantgroup time interaction (P.02)for the outcome of disability (ODQ),but not for pain (NPRS) (P.07).Table 2 provides results at each time

point with 95% confidence intervals(CIs) for differences in ODQ andNPRS scores between groups. Signif-icantly greater improvement was ob-served in the EOTA group for theODQ at each follow-up period(Fig. 3), but only at 1 week for theNPRS (Fig. 4).

Information on additional treatmentsor health care utilization was pro-

vided by 34 subjects (71%), 17 ineach treatment group. No differ-ences in additional treatments orhealth care utilization were foundbetween groups at the 6-monthfollow-up. Of the subjects returninginformation, 2 in each treatment

group had surgery over the 6-monthperiod, 5 in each group had receivedadditional physical therapy treat-ment, and 5 in each group wereseeking additional treatment for LBPat the time of the 6-month follow-up.

After 1 week, 1 subject in thestrengthening group (4.5%) and 7subjects in the EOTA group (26.9%)had central symptoms (P.04),

whereas 6 subjects in the strength-ening group and 17 subjects in theEOTA group showed improvementin pain location (P.008). At the4-week follow-up, 4 subjects in the

strengthening group and 7 subjectsin the EOTA group had central symp-toms (P.47), and 5 and 13 subjectsin the strengthening and EOTAgroups, respectively, showed im-provement in pain location (P.05)(Fig. 5).

Because of the disproportionate

number of subjects with a history oflumbar surgery in the EOTA group(n5), we compared the outcomesin the subjects receiving EOTA witha history of lumbar surgery with thesubjects receiving EOTA without a

Table 1.Baseline Demographic and Self-Reported Variables for Both Treatment Groupsa

All Subjects(N48)

Strengthening Group(n22)

EOTA Group(n26)

Age, y 39.0 (10.2) 37.9 (10.0) 40.0 (10.4)

Sex, % female 31.3 31.8 30.8

Body mass index, kg/m2 27.0 (6.6) 25.9 (2.5) 28.0 (8.6)

Current smokers, % 14.6 9.1 19.2

History of low back pain, % 64.6 59.1 69.2

Median duration of current symptoms, d (range) 59.5 (21,550) 59.5 (81,095) 63.5 (21,550)

Taking medication for low back pain at baseline, % 87.5 81.8 92.3

Narcotic medication use for low back pain this episode, % 31.3 27.3 34.6

Received physical therapy prior to this episode, % 20.8 18.2 23.1

Prior lumbar spine surgery, % 10.4 0 19.2

Missed any work for this injury, % 43.8 45.5 42.3

Have not missed any work in the past 6 mo, % 70.8 68.2 73.1

Symptoms distal to the knee, % 56.3 50.0 61.5

FABQ physical activity subscale score 15.7 (5.4) 15.0 (5.2) 16.4 (5.6)

FABQ work subscale score 14.7 (10.7) 15.4 (10.9) 14.1 (10.7)

ODQ score 37.0 (12.9) 35.2 (10.5) 38.5 (14.7)

NPRS score 5.0 (1.7) 4.9 (1.9) 5.2 (1.6)

aValues presented as mean (SD) unless otherwise stated. EOTAextension-oriented treatment approach, FABQFear-Avoidance Beliefs Questionnaire,ODQmodified Oswestry Low Back Pain Disability Questionnaire, NPRSNumeric Pain Rating Scale.




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history of surgery, using ANCOVAprocedures as previously described

with the baseline score serving asthe covariate. Significantly less im-provement in disability (ODQscores) was found in the subjects

with a history of surgery after 1 week(mean difference14.7 points, 95%CI1.5, 27.8) and 4 weeks (mean

difference19.0 points, 95% CI3.4, 34.6). The difference at 6months approached significance(P.07) even with a small number ofpatients (Fig. 6). Differences inchanges in pain did not reach statis-tical significance.

DiscussionRecent studies1820 have reportedthat using specific inclusion criteriato identify more homogenous sub-groups of subjects and attempting tomatch treatment to the subgroup hasthe potential to enhance treatmenteffects. Several previous studies ex-amining the effectiveness of anEOTA treatment in a more heteroge-

neous group of subjects10,11,13 havefailed to find significant differences

when compared with alternativetreatment procedures. The presentstudy examined a more homogenoussample (those with symptoms distal

Table 2.Change in Outcome Measures Over Timea

Measureb Strengthening Group EOTA Group Mean Difference BetweenGroups From Baseline(95% CI)

1-wk change (95% CI)

ODQ 4.2 ( 0.70, 11.1) 13.1 (6.9, 19.4) 8.9 (2.0, 15.9)

NPRS 0.30 ( 0.70, 1.3) 1.7 (0.80, 2.7) 1.4 (0.41, 2.5)

4-wk change (95% CI)

ODQ 5.8 ( 3.5, 15.2) 20.2 (11.6, 28.8) 14.4 (4.8, 23.9)

NPRS 1.0 ( 0.30, 2.3) 2.3 (1.0, 3.6) 1.2 ( 0.22, 2.7)

6-mo change (95% CI)

ODQ 8.2 ( 1.7, 18.0) 22.7 (13.7, 31.7) 14.6 (4.6, 24.6)

NPRS 1.4 ( 0.10, 2.9) 2.5 (1.1, 3.9) 1.1 ( 0.42, 2.6)

a EOTAextension-oriented treatment approach, ODQmodified Oswestry Low Back Pain Disability Questionnaire, NPRSNumeric Pain Rating Scale.b Change scores adjusted for covariate.

6 mo4 wk1 wkBaseline

Time

45

40

35

30

25

20

15

10

5

0

erocSQ

DOnaeMdetsujdA

EOTA

Strengthening

* =.01

* =.004* =.005

Figure 3.Adjusted modified Oswestry Low Back Pain Disability Questionnaire (ODQ) scores ateach assessment point. Asterisk (*) indicates significant difference between groupsin change from the baseline score (P.05). EOTAextension-oriented treatment ap-proach.




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to the buttock demonstrating cen-tralization with lumbar extension)and found significant differences in

improvement in disability at eachfollow-up period. These findings

support the hypothesis of improvedoutcomes when interventions arematched to more specific subgroupsof patients. The small size and meth-odological shortcomings of the cur-rent study, however, indicate a per-sistent need for additional research

investigating an EOTA approach us-ing larger samples with longer andmore complete follow-ups.

This study attempted to identify asubgroup of subjects a priori who

were expected to respond more suc-cessfully to an EOTA than to otherinterventions. The inclusion criteria

were based on previous reports sug-gesting that subjects centralizing

with extension movements will im-prove if they are given exercises thatencourage end-range movement inthe direction of extension.8,39 Theseprevious reports were supported by

the work of Long et al21 who dem-onstrated greater improvement in

disability over 2 weeks when subjects with a directional preferencefor extension were given an exercisematched to that preference. The cur-rent study extends this previous

work by showing that subjects who

centralized with extension who were given a treatment programmatched to that direction hadgreater reductions in disability for upto 6 months than similar subjects

who were given a strengthening ex-ercise program that has demon-strated merit in other subgroups ofpatients with LBP.32,40 In contrast to

the study by Long et al,21 no ad- vanced training or certification wasrequired of the therapists participat-ing in this study, perhaps resulting ingreater generalizability to physicaltherapists without specific training.

Further research is needed to clarifywhether subjects who demonstrate a

0

2

4

6

8

10

12

14

16

18

20

CentralSymptoms

Improved

Strengthening

EOTA

1 Wk 4 Wk

*

**

CentralSymptoms

Improved

Figure 5.Number of subjects with central symptoms or improved pain location at 1- and 4-week

follow-ups. Asterisk (*) indicates P.05 for the difference between groups, doubleasterisk (**) indicates P.05 for difference between groups. EOTAextension-orientedtreatment approach.

Figure 4.Adjusted Numerical Pain Rating Scale (NPRS) scores at each assessment point. Asterisk(*) indicates significant difference between groups in change from the baseline score(P.05). EOTAextension-oriented treatment approach.




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preference for extension (ie, a direc-tional preference or centralization)constitute a discrete subgroup of pa-tients and, if so, what the optimalintervention strategy may be for thissubgroup. The current study did notfind significant differences in pain re-duction between groups over the

course of the study, and we wereunable to document differences inresource utilization at the 6-monthfollow-up. These results indicate thatadditional research to more narrowlydefine the subgroup of patients thatbest responds to an EOTA would bebeneficial. A clinical prediction ruleto help accurately identify those pa-

tients who will most likely improvewith an EOTA could allow for betterdelineation of this subgroup of pa-tients by clinicians and improve theinclusion criteria for future clinicaltrials.

A potentially important factor identi-fied in this study was the failure ofsubjects with a history of lumbar sur-gery to respond to an EOTA as suc-cessfully as other subjects. This find-ing suggests that patients with ahistory of surgery, even those whoexperience centralization with ex-

tension movement, may benefitmore from a different treatment ap-proach. However, the number ofsubjects in this study with a priorhistory of surgery was small (n5),and none were randomly chosen toreceive the strengthening exercisetreatment, preventing a comparisonof the outcome of an EOTA ap-

proach to an alternative in subjectswho had a history of lumbar surgery.

Several shortcomings of the presentstudy should be considered in assess-ing the results. Inherent in studies

performed in military settings is thepotential that results will not be gen-eralizable to all populations. For this

study, 30 subjects (63%) were re-cruited from military settings and 18

subjects (37%) were recruited fromcivilian settings. However, these subjects had a mean age of 39.0 years(SD10.2) years and body mass in-dex of 27.0 kg/m2 (SD6.6), indicat-ing that, despite military affiliation,these subjects were not younger or

leaner than the sample as a whole. Although caution is warranted, theresults should be generalizable toother populations of patients withLBP.

A primary concern for this study wasthe 6-month follow-up rate. Six-month data were obtained from 73%

of subjects in the strengtheninggroup and 58% in the EOTA group.Based on the inclusion of active-dutymilitary service members in thestudy, the low 6-month follow-uprate may be partially attributable toextended deployments with no abil-ity to reach subjects via postal orelectronic mail (Fig. 2). The rate of

follow-up loss was apparentlygreater in the EOTA group, raisingadditional concerns. The loss tofollow-up may have resulted in anexaggeration of the differences be-tween the treatment groups, or mayhave attenuated these differences.41

The 6-month results should be inter-preted with caution.

Although the current study showedsignificant differences in improve-ment in disability favoring use of anEOTA approach in this relativelyhomogenous group of subjects, wedid not find differences in improve-ment in pain beyond 1 week or inlong-term resource utilization. There

may be several explanations forthese findings. First, although our in-clusion criteria attempted to identifya relatively homogenous group ofsubjects likely to respond to anEOTA, we still may have included

6 mo4 wks1 wkBaseline

Time

45

40

35

30

25

20

15

10

5

0

AdjustedMeanODQScor

e

prior surgery

no prior surgery

* P=.03

* P=.02

Figure 6.Adjusted modified Oswestry Low Back Pain Disability Questionnaire (ODQ) scores forsubjects in the extension-oriented treatment approach group with or without a historyof lumbar surgery. Asterisk (*) indicates statistically significant difference betweengroups from the baseline score (P.05).




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some subjects who did not havegood potential to respond to anEOTA, such as those with a history of

surgery as mentioned previously.Conversely, we may have excluded

some subjects who may have had ahigh likelihood of a positive re-sponse to an EOTA. We found ap-proximately 20% of individuals withLBP fit our criteria of inclusion in theEOTA subgroup. Although this per-centage is consistent with previous

studies we have conducted,20,42 it ispossible that the subgroup is actuallylarger. For example, Long et al21

used a directional preference insteadof centralization as the criterion forinclusion, and reported that 61% of

patients with LBP displayed a direc-tional preference for extensionmovements. Perhaps a more encom-

passing criterion for inclusion wouldhave resulted in a larger treatmenteffect in our study. Second, theEOTA protocol used, which in-cluded exercise and mobilization,may not have been sufficient to max-imize the improvement. A higherdosage of exercise or mobilizationmay have resulted in a larger treat-

ment effect.

Other studies that have assessed theeffectiveness of extension-orientedexercise in a heterogeneous popula-tion with LBP11,13 have shown mini-mal treatment effects. We looked atthe effectiveness of an EOTA in aspecific subgroup of patients with

LBP by utilizing narrow inclusion cri-teria in order to select a priori amore homogeneous group of pa-tients expected to respond to anEOTA. This study provides prelimi-nary evidence that an EOTA is amore effective treatment than astrengthening approach for patients

with symptoms extending to the but-

tocks or more peripherally whodemonstrate centralization with ex-tension movements. Because thisstudy did not include patients who

were not expected to respond to anEOTA, another possible interpreta-

tion of the results would be that theEOTA approach used in this study issuperior to this strengthening ap-

proach in general, and not specifi-cally to a particular subgroup of

patients. Further validation of the ex-istence of this subgroup of patients who preferentially respond to anEOTA could be achieved throughrandomized trials with broader in-clusion criteria that examine theinteraction among those fitting the

criteria for the EOTA subgroup,treatment received, and outcomes.19

ConclusionIn a subgroup of subjects identified a

priori as expecting to benefit from

an EOTA, subjects who received anEOTA experienced significantlygreater improvements in disabilitythan subjects who received an alter-native trunk strengthening program

that also has evidence for its effec-tiveness in a different subgroup ofpatients. No differences were foundbetween the groups for reductionsin pain beyond 1 week. The resultsof this study support the belief thatpatients who centralize with exten-

sion movements during examinationmay preferentially benefit from a

treatment approach focused on re-peated extension movements.

Dr Childs and Dr Fritz provided concept/idea/research design and fund procurement.

All authors provided writing. Dr Browder, DrChilds, and Dr Cleland provided data collec-tion. Dr Browder, Dr Childs, and Dr Fritzprovided data analysis, Dr Browder providedproject management and clerical/secretarialsupport. Dr Browder and Dr Cleland pro-

vided subjects and facilities/equipment. DrFritz provided institutional liaisons. DrChilds, Dr Cleland, and Dr Fritz providedconsultation (including review of manuscriptbefore submission). The authors acknowl-edge the efforts of Sarah Eberhart, KevinJohnson, Shane Koppenhaver, and IsmaelMagtoto.

A platform presentation of the research wasgiven at the Combined Sections Meeting ofthe American Physical Therapy Association;February 1418, 2007; Boston, Mass.

Funding for the study wasprovided by a researchgrant from the Founda-tion for Physical Therapyto Dr Childs.

The opinions or assertions contained herein

are the private views of the authors and arenot to be construed as official or as reflectingthe views of the US Air Force or Departmentof Defense.

This article was submitted September 28,

2006, and was accepted July 17, 2007.

DOI: 10.2522/ptj.20060297

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