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Clinical Rehabilitation 2014, Vol. 28(9) 892 –901 © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0269215514525059 cre.sagepub.com

CLINICAL REHABILITATION

Intensive, progressive exercise improves quality of life following lumbar microdiskectomy: a randomized controlled trial

George J Beneck1, John M Popovich Jr2, David M Selkowitz3, Stan Azen4 and Kornelia Kulig5 on behalf of Physical Therapy Clinical Research Network (PTClinResNet)

Abstract Objective: The purpose of the study was to examine changes in quality of life measures in patients who have undergone an intensive exercise program following a single level microdiskectomy. Design: Randomized controlled trial with blinded examiners. Setting: The study was conducted in outpatient physical therapy clinics. Subjects: Ninety-eight participants (53 male, 45 female) who had undergone a single-level lumbar microdiskectomy allocated to receive exercise and education or education only. Interventions: A 12-week periodized exercise program of lumbar extensor strength and endurance training, and mat and upright therapeutic exercises was administered. Outcome measures: Quality of life was tested with the Short Form 36 (SF-36). Measurements were taken 4–6 weeks postsurgery and following completion of the 12-week intervention program. Since some participants selected physical therapy apart from the study, analyses were performed for both an as- randomized (two-group) design and an as-treated (three-group) design. Results: In the two-group analyses, exercise and education resulted in a greater increase in SF-36 scales, role physical (17.8 vs. 12.1) and bodily pain (13.4 vs. 8.4), and the physical component summary (13.2 vs. 8.9). In the three-group analyses, post-hoc comparisons showed exercise and education resulted in a greater increase in the SF-36 scales, physical function (10.4 vs. 5.6) and bodily pain (13.7 vs. 8.2), and the physical component summary (13.7 vs. 8.9) when compared with usual physical therapy. Conclusions: An intensive, progressive exercise program combined with education increases quality of life in patients who have recently undergone lumbar microdiskectomy.

1 Department of Physical Therapy California State University Long Beach, Long Beach, CA, USA

2 Center for Orthopedic Research, Michigan State University, East Lansing, MI, USA

3 Department of Physical Therapy Education, Western University of Health Sciences, Pomona, CA, USA

4 Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA

525059CRE0010.1177/0269215514525059Clinical RehabilitationBeneck et al. research-article2014

Article

5 Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA

Corresponding author: George J Beneck, Department of Physical Therapy, California State University, Long Beach, 1250 Bellflower Blvd, ET 122, Long Beach, CA 90840, USA. Email: [email protected]

Beneck et al. 893

Keywords SF-36, lumbar microdiskectomy, intensive exercise

Received: 11 November 2013; accepted: 26 January 2014

Introduction

Lumbar diskectomy is one of the most common neurosurgical procedures performed in the United States. Individuals with a lumbar disk herniation, or postspinal decompression surgeries, may pre- sent with pain and decreased ability to perform cer- tain daily activities, which may ultimately lead to diminished health and quality of life in this patient population. A generic measure of perceived health status, the Short Form 36 (SF-36, Medical Outcomes Trust, Boston, MA), was developed as a multipurpose, short-form health survey with only 36 questions.1,2 This questionnaire has been used to assess quality of life in patients with low back pain (LBP), as well as patients following various spine surgeries.

Most studies documenting quality of life changes in microdiskectomy patients report sig- nificant improvements.3–10 Many of these improved outcomes are assessed postsurgically, or after specific time points after the surgery, with brief or no mention of any postsurgical care. Weinstein et al.10 compared surgical vs. non-surgi- cal (usual care) intervention as a treatment for disk herniations, in which the non-surgical group con- sisted of physical therapy. The surgical group had greater improvement in SF-36 scores when com- pared with the non-surgical group, but both dem- onstrated improvements. The physical therapy intervention specifics were not reported, but the results suggest physical therapy intervention may improve quality of life in patients with low back problems. To adequately assess the effects of reha- bilitation on improvements in quality of life, an attempt to control for postsurgical intervention is necessary.

Physical therapy aimed at improving trunk and lower extremity function may play a role in improving quality of life in persons following microdiskectomy. A high-intensity lumbar extensor

strengthening program has shown to promote improvements in SF-36 scores following eight weeks of training in persons with non-specific LBP, however, improvements did not differ from low-intensity or controls at a later 24-week follow- up.11,12 In persons four weeks after undergoing lumbar microdiskectomy surgery, components of the SF-36 correlated with back extensor endurance times.13 While improvements in quality of life have been demonstrated in patients with non-specific LBP following an intense exercise program,12 evi- dence is lacking for persons who have undergone an intensive postoperative exercise program fol- lowing single-level lumbar microdiskectomy sur- gery. Previously, we reported the effects of an intensive exercise program on disability and func- tional performance in patients following lumbar microdiskectomy.14 Therefore, the purpose of this study was to evaluate changes in health-related quality of life measures in this patient population.

Methods

Study design

This study was a prospective randomized con- trolled trial with blinded examiners. The methods used in the development and implementation phases of the study protocol and the study popula- tion have been described elsewhere.14,15 The study and its informed consent process were approved by the Institutional Review Board of the University of Southern California (USC).

Randomization and interventions

Adults between the ages of 18 and 60 who were scheduled to undergo a single-level lumbar micro- diskectomy for the first time between December

894 Clinical Rehabilitation 28(9)

2003 and January 2006 were screened for inclu- sion. Participants were randomly assigned using blocked randomization from a computer-generated list by the Data Management Center of the Physical Therapy Clinical Research Network (PTClinResNet).15 After consenting to the study, the study coordinator informed the participant about his or her group allocation. Allocation was to one of two groups: one session of back care educa- tion (education only), or a back care education ses- sion followed by the 12-week USC Spine Exercise Program (exercise and education). Both the educa- tion session and the exercise program were admin- istered by “intervention” physical therapists at participating physical therapy clinics in the greater Los Angeles area. To ensure the proper implemen- tation of the intervention, each interventional ther- apist participated in eight hours of intervention training and passed the two-hour patient-based exam.14 Intervention therapists were required to complete a one-page-per-day form for each ses- sion. For each participant, the first three forms were faxed to the trial’s central office to check completeness and quality.

Education comprised a one-hour “one-on-one” session with the intervention therapist that occurred after the pre-intervention testing session, four to six weeks after surgery. This educational session was tailored specifically for individuals who had undergone a lumbar microdiskectomy, to help them understand their back problem and how to care for their back. It was guided by an educational booklet that was created especially for this study.15

The exercise program14 comprised back exten- sor strength and endurance training, accompanied by trunk and lower extremity exercise training, which were performed within the same sessions. It began within a few days of the education session, and occurred three times a week for 12 weeks. The program was systematic and individualized, thus accommodating participants of varying levels of fitness and symptoms, and allowing measurable progression of the workload over the 12-week training period. The back extensor strength and endurance training portion of the program was designed to load the back extensor muscles in a graded manner using a variable-angle Roman chair.

The purpose of the trunk and lower extremity exer- cise training was to progressively and dynamically develop strength, endurance, and control of move- ment by the trunk and lower extremity musculature by performing exercise progressions in each of three postures: supine, quadruped, and standing. Exercise progression was based on each partici- pant’s symptoms, use of correct technique, and rate of perceived exertion.

Outcome measures and follow-up

All outcome measurements were obtained by eval- uators who were blinded to group allocation, and who successfully completed standardized training in the testing procedures.14 Testing on all outcome measures began four to six weeks after surgery. Blinding of the intervention therapists and partici- pants was not possible owing to the nature of the intervention.

The SF-36 questionnaire yields an eight-scale profile of scores, as well as physical and mental component summary measures.2 The eight-scale profile of the SF-36 includes physical function, role physical, bodily pain, general health, vitality, social function, role emotional, and mental health components. It has been used in patients with LBP16,17 and after lumbar surgeries.18–20

Statistical analysis

Power calculations were performed based on data from prior published studies, using an alpha level of 0.05 and power of 0.8.21–25 Accounting for attri- tion, each group was estimated to need approxi- mately 50 participants.14

Coded data for all outcome measures and rele- vant independent measures were transferred by the blinded evaluators to data management and analy- sis personnel. These data were then transferred from hardcopy recordings to a menu-driven web- based SQL data entry system (PTClinResNet), and then exported to SAS version 8.2 (SAS Institute Inc., Cary, NC, USA) for statistical analysis.14

A two-group, pretest-posttest (repeated meas- ure) design was originally planned. However, some of the participants did not adhere with the random

Beneck et al. 895

assignment to a particular group and, instead, self- selected a course of physical therapy at a clinic of their choosing. This created a third group that we called “usual physical therapy”. Therefore, both a two-group design (for those participants who com- pleted intervention and testing as randomized) and a three-group design (based on actual treatment received) was used to analyze the data.

The change scores (posttest minus pretest) for both the two-group and three-group designs were assessed using an analysis of covariance (ANCOVA) for each outcome measure, with the baseline/pretest as the covariate. For the three- group design, if the ANCOVAs for any of the out- come measures were significant, post-hoc testing

was performed using Tukey’s method to determine statistically significant pair-wise comparisons between the groups.26 All alpha levels were 0.05. Owing to the higher drop-out rate in the education- only group, an intention-to-treat analysis was not performed. Such analysis would bias in favor of the exercise and education group.14

Results

A total of 176 patients were screened for this study (Figure 1). Of the 176 patients screened, 98 were randomized into either exercise and education (n = 51) or education only (n = 47). Of these 98 partici- pants, a total of 77 completed evaluations at each of

Figure 1. CONSORT flow diagram of participants through the study. Reproduced with kind permission from the American Physical Therapy Association.14 LBP: low back pain.

896 Clinical Rehabilitation 28(9)

the specified time points. Participant demographic information from the exercise and education (n = 45) or education only (n = 32) groups are presented in Table 1. Owing to lack of adherence with group assignment, participants were further categorized into three groups: Education and exercise (n = 43), education only (n = 14), and usual physical therapy (n = 20). Of all study participants completing the intervention period, 3.9% (3/77 participants) expe- rienced an adverse event, all considered not related to the study.14

Analyses performed on the outcome measures for the two-group (as randomized) assignment are presented in Table 2. The ANCOVA results showed significant differences in the postintervention scores between the exercise and education group and education only group for SF-36 role physical (P = 0.012) and SF-36 bodily pain (P = 0.007), indicat- ing that the exercise and education group had sig- nificantly greater improvement in these variables.

Comparisons for the three groups (as-treated – exercise and education, education only, and usual physical therapy) are presented in Table 3. Similar to the two-group analysis, the ANCOVA results for the postintervention scores demonstrated signifi- cant differences in the SF-36 role physical (P = 0.041) and SF-36 bodily pain (P = 0.025). SF-36 physical function was also significantly different (P = 0.023) when compared across the three groups. Post-hoc comparisons showed these sig- nificant improvements existed in the exercise and education compared with the usual physical ther- apy group for each variable (SF-36 bodily pain, P = 0.029; SF-36 physical function, P = 0.034), except for SF-36 role physical (P = 0.125). No sig- nificant differences in postintervention scores were found between the exercise and education and edu- cation only groups, or between the education only and usual physical therapy groups (all, P > 0.05).

Discussion

In both the randomized (two group) and as-treated (three group) analyses, the patients treated with exercise and education achieved greater improve- ments in the SF-36 role physical and bodily pain scales and the physical component summary.

Additionally, in the as-treated analysis, the exer- cise and education group achieved greater improve- ments in SF-36 physical function scale. No differences were identified between the exercise and education group and the education-only group in the as-treated analyses. This is best explained by the loss of statistical power resulting from the high number of participants who did not adhere to their assignment in the education only group. The results of the current study are similar to those of Harts and colleagues.12 In that study, greater increases in SF-36 scores were achieved in a group participat- ing in a high-intensity lumbar extensor program, as compared with both low-intensity and a control group. However, the participants in that study had chronic LBP without signs of nerve root compres- sion and had not received a lumbar spine surgical intervention. Although several studies27–31 have examined the effects of rehabilitation following lumbar diskectomy, only one reported the effects of rehabilitation on health-related quality of life.28 In that study, an eight-week exercise program, target- ing trunk muscle performance and hip mobility combined with a behavioral approach including graded activity, was compared with one session of home exercise instruction following beginning 0–3 weeks following first-time lumbar microdiskec- tomy. Health-related quality of life was measured using both the SF-36 and the European Quality of Life Scale (EuroQol). In contrast to the current study, the group receiving the home-based program achieved greater increases in three of the SF-36 scales and the EuroQol visual analogue scale. To our knowledge, the current study is the first to demonstrate greater improvements in health- related quality of life from a standardized clinic- based exercise program in patients post lumbar microdiskectomy.

The three scales of the SF-36, role physical, bodily pain, and physical function, shown to increase in the current study, are all part of the physical component summary of the SF-36, in con- trast to SF-36 scales, vitality, social function, role emotional, and mental health, which primarily form the mental component summary. The SF-36 role physical, bodily pain, and physical function scales correlate most highly with, and contribute

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Table 1. Baseline demographic, primary outcomes, and participation measures by randomization groups (N = 98).

Variable Exercise and education (n = 51)

Education only (n = 47)

P

Demographics Age (years) 39.2 (10.2) 41.4 (9.9) 0.90 Gender: male 29 (58%) 24 (50%) 0.43 Latino or Hispanic 6 (12%) 9 (19%) 0.35 Race Black or African American 1 (2%) 1 (2%) 1.00 White 35 (70%) 34 (71%) Unspecified or Other 14 (28%) 13 (27%) Involved in a litigation process with Workers’ Compensation

4 (9%) 9 (19%) 0.14

Medical history Duration of pain episode prior to

surgery (months) 6.7 (9.8) 5.9 (7.0) 0.66

Time since first onset of low back pain (months)

82.1 (93.3) 120.7 (125.3) 0.12

Time since first onset of sciatica (months)

33.1 (67.6) 38.7 (69.8) 0.71

Number of previous episodes <3 13 (32%) 16 (34%) 0.75 3–5 3 (7%) 5 (11%) 5–10 5 (12%) 3 (6%) >10 13 (32%) 18 (38%) unspecified 7 (17%) 5 (11%) Involved spinal level(s): L4/L5 19 (38%) 24 (50%) 0.35 L5/S1 30 (60%) 24 (50%) L2/L3 1 (2%) 0 (0%) Positive passive straight leg raise 29 (63%) 19 (45%) 0.09 SF-36 Physical function 40.5 (8.9) 37.6 (9.8) 0.13 Role physical 32.4 (10.5) 31.9 (10.5) 0.82 Bodily pain 37.7 (7.8) 35.6 (7.3) 0.18 General health 51.8 (8.3) 49.3 ((9.2) 0.17 Vitality 48.1 (8.8) 45.6 (9.5) 0.20 Social function 35.7 (10.2) 35.8 (12.1) 0.95 Role emotional 47.8 (10.6) 43.6 (13.8) 0.11 Mental health 50.0 (8.5) 47.7 (9.5) 0.23 Physical component summary 36.8 (8.2) 35.3 (8.4) 0.39 Mental component summary 50.3 (9.9) 47.8 (11.3) 0.24

Values are mean (±SD) for continuous variables; frequency (%) for categorical variable. Chi-square tests were used for categorical variables and a one-way ANOVA for continuous variables. Missing data for the following variables (exercise and education, education only): Involved in a litigation process with Workers’ Compensation (4, 0); duration of pain episode prior to surgery (4, 6); time since first onset of low back pain (10, 9); time since first onset of sciatica (12, 2); number of previous episodes (4, 6); positive passive straight leg raise (5, 5); physical Function (0, 1).

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most to, the physical component summary score32 and are reported to be the most valid SF-36 scales for measuring physical health.33 They are also con- sidered most responsive to interventions intended to improve physical health.33 In contrast to just reporting a single summary, such as the physical component summary score, we chose to analyze the individual scales because they have the poten- tial of yielding a richer interpretation of the results. Furthermore, a comparison of scoring methods demonstrated that the best physical health test con-

sistently performed better than the physical com- ponent summary score.34

In contrast to the SF-36, condition-specific functional measures, such as the Oswestry Disability Index or the Roland–Morris Disability Questionnaire, focus on symptoms and dysfunc- tions believed to be important to both patients and clinicians. The primary focus of these measures is on activity restrictions and postural limitations.35 In contrast to these measures, the items in the SF-36 pertaining to physical health encompass a

Table 2. SF-36 quality of life measures based on two-group (as randomized) analyses. Values are change (baseline– post) scores (95% confidence interval).

Outcome measures Exercise and education (n = 45)

Education only (n = 32)

P

Physical function 9.53 (7.4 to 11.7) 7.18 (4.6 to 9.7) 0.052 Role physical 17.81 (15.0 to 20.6) 12.07 (8.1 to 16.1) 0.012 Bodily pain 13.44 (10.5 to 16.4) 8.37 (6.2 to 10.6) 0.007 General health 2.00 (0.2 to 3.8) 0.40 (−2.9 to 3.7) 0.216 Vitality 7.24 (4.7 to 9.8) 6.73 (3.9 to 9.5) 0.544 Social function 15.88 (12.5 to 19.3) 12.44 (8.8 to 16.1) 0.331 Role emotional 6.01 (2.8 to 9.2) 4.64 (−0.5 to 9.7) 0.068 Mental health 4.22 (1.5 to 6.9) 2.08 (−1.0 to 5.2) 0.131 Physical component summary 13.19 (11.0 to 15.3) 8.93 (6.5 to 11.3) 0.010 Mental component summary 4.87 (1.8 to 7.9) 4.10 (0.5 to 7.7) 0.351

The P-value is a between-group comparison of the postintervention scores using ANCOVA for the overall (covariate = baseline).

Table 3. SF-36 quality of life measures based on actual intervention received. Values are change (baseline–post) scores (95% confidence interval).

Outcome measures Exercise and education (n = 43)

Education only (n = 14)

Usual physical therapy (n = 20)

P

Physical function 10.35 (8.2 to 12.5) a 7.22 (2.6 to 11.9) 5.64 (3.0 to 8.3) 0.023 Role physical 18.51 (15.8 to 21.2) 7.91 (3.7 to 12.1) 13.55 (7.7 to 19.4) 0.041 Bodily pain 13.71 (10.8 to 16.7)a 8.13 (4.3 to 12.0) 8.20 (5.3 to 11.1) 0.025 General health 2.05 (0.1 to 4.0) 2.38 (−2.3 to 7.1) −0.91 (−5.0 to 3.2) 0.644 Vitality 7.33 (4.7 to 10.0) 6.00 (0.8 to 11.2) 7.02 (4.0 to 10.0) 0.936 Social function 15.85 (12.3 to 19.4) 14.02 (8.9 to 19.1) 11.73 (6.7 to 16.7) 0.547 Role emotional 6.69 (3.5 to 9.9) 4.19 (14.67) 3.48 (−3.2 to 10.2) 0.163 Mental health 4.13 (1.4 to 6.9) 3.90 (−3.5 to 11.9) 1.22 (−2.3 to 4.7) 0.563 SF-36 physical component 13.65 (11.6 to 15.7)a 7.75 (4.4 to 11.1) 8.91 (5.4 to 12.4) 0.022 SF-36 mental component 4.87 (1.7 to 8.0) 5.31 (−1.2 to 11.8) 3.31 (−0.6 to 7.3) 0.797

The P-value is a between-group comparison of the postintervention scores using ANCOVA for the overall (covariate = baseline). aSignificant difference (P ≤ 0.05) for post-hoc analysis between the exercise and education group and the usual physical therapy group.

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wider array of activities and potential effects on physical health. While there are some similarities between these measures and the scales of the SF-36 related to physical health, these outcomes measure different constructs.36 Furthermore, the SF-36 scales, vitality, social function, role emotional, and mental health, provide an outcome of mental health that is gleaned by the functional measures.35 In the current study, no significant differences were iden- tified between groups in either of the analyses, sug- gesting that the intervention benefits of the exercise and education intervention were mainly physical.

In a systematic review examining the effects of rehabilitation on short-term pain reduction follow- ing lumbar disk surgery,31 the authors reported low-quality evidence indicating that exercises are more effective than no treatment and that there is no significant differences between supervised exercise and home exercises for short-term pain relief. Since that review, only one29 of four stud- ies27–30 reported greater pain reduction in persons participating in an exercise program postdiskec- tomy. In nearly all studies, a visual analogue scale was typically used to quantify back pain. In the current study, the body pain scale of the SF-36 shows significantly greater reductions in pain in both analyses. The body pain scale of the SF-36 differs from the visual analogue scale in that it is a composite score calculated from two questions: (1) pertaining to the severity of bodily pain, and (2) how much did pain interfere with work. One could argue that question 2 could equally be a measure of function, and thus explain the significant differ- ences reported in the current study.

One limitation of the study is that a large num- ber of participants did not adhere to the original allocation into the education-only group, which suggested a preference for the exercise and educa- tion intervention. Since more motivated subjects may have dropped out of the education-only group, an analysis excluding that data may have hindered the outcomes of that group. The more conservative option of analyzing the evaluable data in the two groups was chosen. Thus, several subjects who received physical therapy outside the study were included in the education-only group in the two- group analysis. A more detailed discussion of this issue can be found in our previous report.14

A second limitation is the disparity of time spent with a physical therapist between groups, i.e. the education and exercise group received more one- on-one time than the other groups. Measured out- comes can be influenced by time spent with a therapist. However, it is important to point out that greater time spent with a physical therapist may not necessarily increase health-related quality of life outcome measures. Two previous studies of physi- cal therapy intervention effects on health-related quality of life from low back disorders with greater time spent with the therapist showed no differences in the increase in quality of life between these groups.37,38 Furthermore, a third study reported greater increases in health-related quality of life in a group that received a home-based program in con- trast to participants in a clinic-based program.28

Improvements in quality of life measurements favor individuals who performed an intensive 12-week strength and endurance training program of the trunk and lower extremity musculature. These postintervention improvements manifest in domains typical of physical therapy and patient- oriented outcomes. The results of this clinical trial support the role of an intensive 12-week strength and endurance training program of the trunk and lower extremity musculature for patients having undergone first-time single-level microdiskectomy. However, the long-term effects of such a program for patients having undergone first-time single- level microdiskectomy remain to be determined.

Clinical messages

• Intensive exercise may improve quality of life following lumbar microdiskec- tomy more than education alone or usual physical therapy.

• Quality of life gains following intensive exercise are in the physical domain of the SF-36.

Acknowledgements

Physical Therapy Clinical Research Network (PTClinResNet): Network Principal Investigator is Carolee J Winstein and Co-Principal Investigator

900 Clinical Rehabilitation 28(9)

is James Gordon (both at University of Southern California). Project Principal and Co-Principal Investigators are: David A Brown (Northwestern University); Sara Mulroy and Bryan Kemp (Rancho Los Amigos National Rehabilitation Center); Loretta M Knutson (University of Indianapolis); Eileen G Fowler (University of California at Los Angeles); and Sharon K DeMuth, Kornelia Kulig, and Katherine J Sullivan (University Southern California). The Data Management Center is located at the University of Southern California and is directed by Stanley P Azen. The four-member Data Safety and Monitoring Committee are: Nancy Byl, Chair (University of California at San Francisco), Hugh G Watts (Shriners’ Hospital for Children–LA Unit, Los Angeles, California), June Isaacson Kailes (Western University, Los Angeles, California), and Anny Xiang (University of Southern California).

Conflict of interest

The authors declare that there is no conflict of interest.

Funding

This study was funded by a grant from the Foundation for Physical Therapy. Institutional Review Board of the University of Southern California.

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