Lumbar Spine Muscle Degeneration Inhibits Rehabilitation-Induced Muscle Recovery

Study Overview
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Brief Summary
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Low back pain (LBP) is a complex condition that affects 65-85% of the population, and is the leading musculoskeletal condition contributing to disability in the United States. Disc herniation is the most common injury and 75% of individuals undergoing surgical and rehabilitative interventions for this condition experience suboptimal or poor outcomes. These patients demonstrate disability and deficits in functional capacity, including strength and endurance of the lumbar musculature. Muscle-specific changes in individuals with LBP include altered muscle volume, fatty infiltration and fibrosis, and fiber area and type. Importantly, these changes are insensitive to rehabilitation in patients with continued chronic or recurrent symptoms. While normal disuse-related atrophy in the presence of LBP is expected, more severe or chronic pathology, such as inflammation and fiber damage, may be inducing irreversible fiber degeneration and fatty/fibrotic tissue changes that impair muscle function and recovery. While the structural and adaptive capacities of healthy muscle are well understood, muscle recovery in the presence of pathology is less clear. To address this gap in knowledge, the purpose of this project is to compare structural, physiological, and adaptive responses of muscle in the presence of acute and chronic lumbar spine pathology. The central hypothesis is that chronic injury results in a state of muscle inflammation, atrophy, fibrosis, and muscle degeneration that is not responsive to exercise. The Investigators will identify which patients respond to exercise by examining muscle hypertrophic, fibrotic, inflammatory, and adipogenic gene expression profiles. Patients will be followed for six months post-operatively to measure muscle recovery and strength.

Detailed Description
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AIM: To determine the effect of exercise on induction of muscle hypertrophic, fibrotic, inflammatory, and adipogenic pathways in patients with mild versus severe fatty infiltration of the multifidus muscle. Rationale. The objectives of this aim are to 1) measure molecular responses of muscle to a well-defined bout of pre-operative exercise, and 2) to determine if baseline morphological or exercise-induced molecular responses predict muscle structural recovery and functional gains up to 6 months post-operatively. Design. This will be a longitudinal study of 40 patients with mild (< 20%) versus severe (> 50%) fatty infiltration. Non-exercise controls will also be important and the investigators intend to use a portion of biopsied tissue from other experiments as additional controls. Prior to surgery, patients will undergo clinical and MRI examinations. Additionally, patients will undergo an exercise bout 6 hours pre-operatively, and then immediately undergo a short MRI imaging protocol to measure exercise-induced perfusion changes (IVIM). Six hours after the exercise bout, the investigators will collect biopsies of the multifidus during surgery to characterize the hypertrophic, fibrotic, adipogenic, and inflammatory responses. For primary analyses, patient groups will be selected on the basis of severity of muscle fatty infiltration. Group ages and genders will be matched because the investigators know that baseline and exercise-induced gene expression varies with age. Surgical procedure and manipulation of the disc intraoperatively will be documented to account for the potential for disc and other surgery-specific effects on muscle structure. Six months post-operatively, repeated measures of muscle structure will be made via MRI. At 6, 12, and 24 weeks, strength (isokinetic dynamometer) and patient-specific function (questionnaire data) will be obtained as per standard protocol. Methods: Physical Examination: A physical therapist with spine injury experience will conduct the clinical exam. Age, gender and body mass index (BMI), duration of symptoms, anti-inflammatory drug use, active and passive range of motion, provocative neural tension tests (measuring joint range of motion [ROM]), strength and endurance as measured on an isokinetic dynamometer (MedX Holdings Inc.), neurovascular status, Oswestry Disability Index (81), Baecke Physical Activity Questionnaire (BPA), Fear Avoidance Beliefs Questionnaire (FABQ), and Pain Catastrophizing Scale (PCS) are important measures that capture both physical and psychosocial factors known to be related to LBP and will be collected at the clinical site. This screen will be used to confirm that discogenic symptoms are isolated to levels below L4, which allows us to use vastus lateralis as an internal control muscle biopsy. Clinical MRI: Standard axial, sagittal oblique, and coronal oblique MR images of the spine will be collected on all patients who are scheduled for surgery. To identify disc injury severity (Pfirrmann grade), muscle fatty infiltration (Kjaer grade), and to confirm injury location, T1 and T2 non-fat suppressed or contrast-enhanced axial and sagittal MR images of the spine joint will be used. Multimodal MRI: Imaging will be performed in a single session on a state-of-the-art 3T MRI system (GE MR750). The quantity and distribution of spine muscle volume, fat volume, and connective tissue volume will be performed from supine scans using high-resolution (1mm3) 3D FSPGR, IDEAL fat-water separation, and UTE pulse sequences, respectively using a 32-channel spine array coil. IVIM will be used to quantify regional muscle activation in response to an exercise bout. Exercise protocol: Prior to surgery, patients will be subjected to a lumbar spine exercise protocol on a MedX Lumbar extension dynamometer with a pelvic restraint system allowing for isolation of lumbar spine muscles. The exercise protocol consists of 1 set of 20 repetitions (range 15-25 reps) at a rate of 5 seconds/repetitions with a starting weight of 60-80% of their computerized strength score. Patients will be instructed to target an exertion level of 7/10 on the Borg Rate of Perceived Exertion (RPE) scale within their available passive ROM range into flexion-extension. Diet protocol: Importantly, the patients will remain NPO (no food or water) after the exercise bout but will have a standardized diet for 24 hours prior to the exercise bout and surgery, which mitigates the effects of diet on gene expression (137, 150-152). Evening meals will be standardized (1900h: 11 kcal/kg; 60% carbohydrate [CHO], 25% fat [FAT], 15% protein [PRO]; 2200h (3 kcal/kg; 95% CHO, 2% FAT, 3% PRO) because meal composition can acutely impact gene and protein expression. Harvesting and storage of muscle biopsy: Muscle biopsies will be harvested within 6 hours of the exercise bout at their scheduled surgery time. Subjects will be excluded from the analysis if their biopsies are not harvested within 1 hour of the prescribed time point. Biopsies will be obtained with a standard biopsy clamp at the middle and deep margins of the multifidus muscle as noted in Aim #1 and immediately placed in RNAlater (Qiagen) for subsequent qPCR analysis or frozen in liquid nitrogen for protein abundance/phosphorylation measurements. qPCR and western blotting: Gene expression and protein abundance will be measured by, qPCR and western blotting, respectively. Briefly, real-time PCR will be performed in a Bio-Rad CFX384 using customized plates (PrimePCR, Bio-Rad). Target gene expression will be calculated relative to values from 18S ribosomal subunit, as preliminary findings demonstrate it to be more stable than glyceraldehyde-3-phosphate dehydrogenase (GAPDH; data not presented). For genes in which we find a greater than 3-fold change in expression, western blotting will be used to assess protein abundance, as previously described.

Official Title
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Lumbar Spine Muscle Degeneration Inhibits Rehabilitation-Induced Muscle

Conditions
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Disc Degeneration, Low Back Pain

Intervention / Treatment
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* Other: Exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Spine pathologies requiring un-instrumented surgery (i.e. laminectomy, laminoforaminotomy, or discectomy). Age 21-85 years of age. Exclusion Criteria: History of lumbar spine surgery. Patients requiring placement of instrumentation as part of the surgical procedure (i.e. fusion). Diabetes. Neuromuscular diseases.

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Stratified by fatty infiltration severity (n=20/group x 2 groups + non exercise controls n=20)
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Exercise<br>A single bout of moderate intensity lumbar extensor muscle exercise. | Other: Exercise<br>* The exercise protocol consists of 1 set of 20 repetitions (range 15-25 reps) at a rate of 5 seconds/repetitions with a starting weight of 60-80% of their computerized strength score. Patients will be instructed to target an exertion level of 7/10 on the Borg Rate of Perceived Exertion (RPE) scale within their available passive ROM range into flexion-extension<br>|
| No Intervention: Non-exercise<br>No exercise intervention. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Multifidus Muscle Fatty Infiltration | (% fat at 6 months - % fat at baseline / % fat at baseline) | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Oswestry Disability Index (ODI) | Disability Questionnaire (10 questions, % scale is sum of 10 questions/50, higher score is worse), 6 months - baseline | 6 Months | 
| Change in Fear Avoidance Beliefs Questionnaire (FABQ) | Fear Avoidance Behaviors (sumo 16 items, 0-64 scale, higher score is worse), 6 months- baseline | 6 months | 
| Change in Pain Catastrophizing Scale (PCS) | Pain behaviors questionnaire (sum of 13 items, 0-52 scale, higher score is worse), 6 months - baseline | 6 months | 
| Change in Activated Muscle Volume (%) | (% muscle activation after exercise - % muscle activation at baseline / % muscle activation at baseline) | After exercise (within 5 minutes) | 
| Change in Pain (VAS) | Visual Analog Scale (0-100 mm scale), 6 months - baseline | 6 months | 
| Change in Strength | MedEx dynamometer, Back Extensor Strength (Nm), 6 months - baseline | 6 months | 
| MYHC3 gene expression (delta CT/delta CT) | Embryonic myosin heavy chain gene expression | 6 hours after a single exercise bout | 
| MHY3 protein abundance (ug/mg) | Embryonic myosin heavy chain protein abundance | 6 hours after a single exercise bout | 
| MYOG gene expression (delta CT/delta CT) | Myogenin gene expression | 6 hours after a single exercise bout | 
| MYOG protein abundance (ug/mg) | Myogenin protein abundance | 6 hours after a single exercise bout | 
| PAX7 gene expression (delta CT/delta CT) | PAX7 gene expression | 6 hours after a single exercise bout | 
| PAX7 gene expression (ug/mg) | PAX7 protein abundance | 6 hours after a single exercise bout | 
| ANKRD2 gene expression (delta CT/delta CT) | ANKRD2 gene expression | 6 hours after a single exercise bout | 
| ANKRD2 protein abundance (ug/mg) | ANKRD2 protein abundance | 6 hours after a single exercise bout | 
| MTOR gene expression (delta CT/delta CT) | MTOR gene expression | 6 hours after a single exercise bout | 
| MTOR protein abundance (ug/mg) | MTOR protein abundance | 6 hours after a single exercise bout | 
| COL1A1 gene expression (delta CT/delta CT) | COL1A1 gene expression | 6 hours after a single exercise bout | 
| COL3A1 gene expression (delta CT/delta CT) | COL3A1 gene expression | 6 hours after a single exercise bout | 
| COL9A1 gene expression (delta CT/delta CT) | COL9A1 gene expression | 6 hours after a single exercise bout | 
| LOX gene expression (delta CT/delta CT) | LOX gene expression | 6 hours after a single exercise bout | 
| CTGF gene expression (delta CT/delta CT) | CTGF gene expression | 6 hours after a single exercise bout | 
| TGFB1 gene expression (delta CT/delta CT) | TGFB1 gene expression | 6 hours after a single exercise bout | 
| MMP1 gene expression (delta CT/delta CT) | MMP1 gene expression | 6 hours after a single exercise bout | 
| MMP3 gene expression (delta CT/delta CT) | MMP3 gene expression | 6 hours after a single exercise bout | 
| MMP9 gene expression (delta CT/delta CT) | MMP9 gene expression | 6 hours after a single exercise bout | 
| CEBPA gene expression (delta CT/delta CT) | CEBPA gene expression | 6 hours after a single exercise bout | 
| FABP4 gene expression (delta CT/delta CT) | FABP4 gene expression | 6 hours after a single exercise bout | 
| PPARG gene expression (delta CT/delta CT) | PPARG gene expression | 6 hours after a single exercise bout | 
| PPARD gene expression (delta CT/delta CT) | PPARD gene expression | 6 hours after a single exercise bout | 
| LEP gene expression (delta CT/delta CT) | LEP gene expression | 6 hours after a single exercise bout | 
| ADIPOQ gene expression (delta CT/delta CT) | ADIPOQ gene expression | 6 hours after a single exercise bout | 
| CASP1 gene expression (delta CT/delta CT) | CASP1 gene expression | 6 hours after a single exercise bout | 
| CASP3 gene expression (delta CT/delta CT) | CASP3 gene expression | 6 hours after a single exercise bout | 
| TNFa gene expression (delta CT/delta CT) | TNFa gene expression | 6 hours after a single exercise bout | 
| IL10 gene expression (delta CT/delta CT) | IL10 gene expression | 6 hours after a single exercise bout | 
| IL6 gene expression (delta CT/delta CT) | IL6 gene expression | 6 hours after a single exercise bout | 
| IL1B gene expression (delta CT/delta CT) | IL1B gene expression | 6 hours after a single exercise bout | 
| COL1A1 Protein abundance (ug/mg) | COL1A1 Protein abundance | 6 hours after a single exercise bout | 
| COL3A1 Protein abundance (ug/mg) | COL3A1 Protein abundance | 6 hours after a single exercise bout | 
| COL9A1 Protein abundance (ug/mg) | COL9A1 Protein abundance | 6 hours after a single exercise bout | 
| LOX Protein abundance (ug/mg) | LOX Protein abundance | 6 hours after a single exercise bout | 
| CTGF Protein abundance (ug/mg) | CTGF Protein abundance | 6 hours after a single exercise bout | 
| TGFB1 Protein abundance (ug/mg) | TGFB1 Protein abundance | 6 hours after a single exercise bout | 
| MMP1 Protein abundance (ug/mg) | MMP1 Protein abundance | 6 hours after a single exercise bout | 
| MMP3 Protein abundance (ug/mg) | MMP3 Protein abundance | 6 hours after a single exercise bout | 
| MMP9 Protein abundance (ug/mg) | MMP9 Protein abundance | 6 hours after a single exercise bout | 
| CEBPA Protein abundance (ug/mg) | CEBPA Protein abundance | 6 hours after a single exercise bout | 
| FABP4 Protein abundance (ug/mg) | FABP4 Protein abundance | 6 hours after a single exercise bout | 
| PPARG Protein abundance (ug/mg) | PPARG Protein abundance | 6 hours after a single exercise bout | 
| PPARD Protein abundance (ug/mg) | PPARD Protein abundance | 6 hours after a single exercise bout | 
| LEP Protein abundance (ug/mg) | LEP Protein abundance | 6 hours after a single exercise bout | 
| ADIPOQ Protein abundance (ug/mg) | ADIPOQ Protein abundance | 6 hours after a single exercise bout | 
| CASP1 Protein abundance (ug/mg) | CASP1 Protein abundance | 6 hours after a single exercise bout | 
| CASP3 Protein abundance (ug/mg) | CASP3 Protein abundance | 6 hours after a single exercise bout | 
| TNFa Protein abundance (ug/mg) | TNFa Protein abundance | 6 hours after a single exercise bout | 
| IL10 Protein abundance (ug/mg) | IL10 Protein abundance | 6 hours after a single exercise bout | 
| IL6 Protein abundance (ug/mg) | IL6 Protein abundance | 6 hours after a single exercise bout | 
| IL1B Protein abundance (ug/mg) | IL1B Protein abundance | 6 hours after a single exercise bout | 
| Change in Multifidus muscle volume (%) | Multifidus muscle volume (cc), (6 months - baseline/baseline) | baseline | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Multifidus, Muscle, Degeneration, Lumbar Spine, Disc