Achieving Lumbar Stabilization Through Chiropractic/Rehabilitation After Radiofrequency Neurolysis

ACHIEVING LUMBAR STABILIZATION THROUGH CHIROPRACTIC/REHABILITATION AFTER RADIOFREQUENCY NEUROLYSIS: RETROSPECTIVE CASE REPORT OF A RECOVERING DRUG ADDICT WITH LUMBAR FACT SYNDROME; DEGENERATIVE DISC DISORDER; AND HERNIATED LUMBAR DISC.

Kent C. Long, D.C.

Private practice of chiropractic, Long Chiropractic Office, Dayton, OH.
Submit requests for reprints to: Dr. Kent C. Long, Long Chiropractic Office, 4978 Northcutt Place, Dayton, Ohio 45414.
Submitted August 25, 2009. Peer reviewed by the American Chiropractic Rehabilitation Board

ABSTRACT
Objective:
This case study discusses management of lumbar disc herniation with degenerative disc disease and facet arthropathy using a program of chiropractic manipulation and an active rehabilitation program, and its effectiveness even after radiofrequency neurolysis has been performed.

Clinical features:
A 25-year-old Caucasian male with three year history of lower back pain and right sciatic pain. Prior medical intervention included physical therapy, treatment with non-steroid anti-inflammatory medications, epidural blocks, lumbar facet injections, and radiofrequency neurolysis, with incomplete resolution of his symptoms. The patient was unable to bend, lift, or sit without pain, and unable to return to regular work or to normal activities of daily living. His lumbar range of motion was restricted in all ranges of motions, severely in flexion and extension. He exhibited a positive SLR and Kemps, producing lower back and right lower extremity pain.

Intervention and outcome:
Treatment plan and intervention consisted of patient education on proper posture and ergonomics, such as proper bending and lifting techniques, for both the home and workplace. An in-office chiropractic and rehabilitative exercise treatment program was commenced, with eventual transition from office based into home based therapy and exercises. The patient initially showed good response to treatment, reporting a decrease in his signs and symptoms and improvement in function with the treatment. Active rehabilitation was continued with the goal of restoring normal range of motion, improving core and spinal stability and strength, and returning the patient to work. Upon reaching these goals he was released to home therapy and supportive chiropractic care with continued positive response.

Conclusion:
Management of lumbar disc herniation with degenerative disc disease and facet arthropathy with chiropractic and active rehabilitation is discussed. A literature review is included. Spinal deconditioning and a weakness of the core and spinal stabilization muscles appeared to be the cause of patient’s symptoms and reduced physical capacities in this particular case. Management including patient education on proper posture, proper lifting techniques, core and spinal stabilization exercises, active strengthening exercise and chiropractic manipulation were effective in this case. Stabilization of the core and spine was able to be achieved with no difficulty, despite the radiofrequency neurolysis procedure that was previously performed.

KEYWORDS
Herniation; Facet Arthropathy; Multifidus; Radiofrequency; Chiropractic Manipulation; Rehabilitation

INTRODUCTION
Low back pain is the most common complaint in orthopedic, neurosurgical, and occupational medicine practices. It is the second most common complaint in primary care. It is the third most common condition requiring surgical procedure. (1)

It has been estimated that 60 to 80% of Americans will suffer low back pain during their lifetime, (2) and most of them will experience recurrent back pain.(3,4) Approximately 14% of the US population experiences lower back pain at a given time.(5) According to Waddell, (6,7) there is a 3 to 5% lifetime prevalence of sciatica (pain below the knee).

Cases of chronic non-cancer pain are both the most frequent and most difficult that the spine care professional is called upon to treat. The majority of patients with potential neurosurgical disorders can improve or stabilize with conservative treatments such as chiropractic, physical, or osteopathic therapies in 6 weeks to 6 months. (3) However, frequently if these conservative approaches do not sufficiently resolve the disorder, patients will progress to more aggressive or more invasive procedures, such as epidural blocks, nerve blocks (facet blocks), radiofrequency neurolysis (neorotomy/rhizotomy), and multiple forms of surgery. In many cases these more invasive procedures fail to sufficiently resolve the disorder, and the patient returns to conservative treatment. Occasionally these more invasive procedures can produce a situation in which certain conservative procedures become less effective, ineffective, or contraindicated; thus possibly no longer making the patient a good candidate for conservative methods of care.

One of the procedures mentioned above, radiofrequency neurolysis, or lumbar medial branch neurotomy, can be an effective means of reducing pain in patients carefully selected on the basis of controlled diagnostic blocks (facet blocks). (8) Nerves leave the spinal cord as mainly primary motor rootlets and sensory rootlets. These join to the nerve root before leaving the spinal canal. After the root canal, the nerve root branches into the ventral root, which contains sensory and motor fibers innervating the extremities, and the dorsal root (i.e. the dorsal ramus), which innervates the posterior structures, for example, the back muscles: the dorsal ramus itself may become irritated (dorsal ramus syndrome). Especially predisposed to entrapment is the medial branch of the dorsal ramus, which innervates the multifidus muscle and also contains pain fibers. (9) The lumbar zygapophysial joint (Z-joint) or facet joints are a potential source of low back pain. In general the principle innervation of the Z-joint is the medial branch of the posterior primary ramus of the same level as the target Z-joint as well as the level above.(70) Ablation of the medial branch of the posterior primary ramus through radiofrequency neurolysis therefore not only reduces pain by affecting the sensory fibers of this nerve, but also denervates the multifidus muscle by affecting the motor fibers of the nerve. In fact, denervation of the multifidus muscle as evaluated by electromyography has become a measurement of successful Z-joint denervation. Sometimes this evaluation has shown the multifidus to be successfully denervated as demonstrated by electromyography, but the Z-joints may be inadequately denervated. (10)

Denervation of the multifidus muscle may also occur in lumbosacral radiculopathy and low back pain syndromes. Asymmetric atrophy of the multifidus muscle has been shown in patients with unilateral lumbosacral radiculopathy. (11) Atrophy of the multifidus muscle has been shown to occur in acute and chronic low back pain. Although chronic changes have been believed to be more widespread, acute changes at one segment are identified within days of injury.(12) Unilateral wasting isolated to one level suggests that the mechanism of wasting is not generalized disuse atrophy or spinal reflex inhibition in acute/subacute low back pain.(13) Recent studies support that the pattern of multifidus muscle atrophy in chronic low back pain patients is also localized rather than generalized. These studies have shown that the pattern of atrophy is both vertebral level and side specific.(14) Chronic low back pain has been shown to not only effect the multifidus muscle in decreased size, but there is also evidence provided of corresponding reduced ability to voluntarily contract the atrophied muscle.(15)

The multifidus muscle may also be a source of local and referred pain.(16) Investigation of the relationships between lumbar multifidus muscle atrophy and low back pain, leg pain, and intervertebral disc degeneration shows the correlation between multifidus muscle atrophy and leg pain to be significant, which may explain referred leg pain in the absence of MRI abnormalities.(17) The activity of the multifidus has been shown to be dysfunctional in people with recurrent unilateral low back pain, despite resolution of symptoms. Because multifidus muscle activity is critical for normal spinal control, this provides a mechanism for recurrent episodes. (18) Multifidus muscle recovery is not spontaneous on remission of painful symptoms. Lack of localized, muscle support may be one reason for the high recurrence rate of low back pain following the initial episode. (19)

Multifidus muscle recovery is more rapid and more complete in patients who receive exercise therapy. (19) Multifidus muscle atrophy can exist in highly active elite athletes with low back pain. Specific stabilization exercise retraining resulted in an improvement in multifidus muscle recovery and a decrease in pain. (20)

The contribution of the multifidus muscles to spinal stability is well established. Five clinical beliefs have arisen: (i) the deep fibers of the multifidus muscle stabilize the lumbar spine whereas the superficial fibers of the lumbar multifidus and the erector spinae extend and/or rotate the lumbar spine. (ii) The deep fibers of the multifidus muscle have a greater percentage of type I (slow twitch) muscle fibers than the superficial multifidus and the erector spinae. (iii) The deep fibers of the multifidus muscle are tonically active during movements of the trunk and gait, whereas the superficial multifidus and erector spinae are phasically active. (iv) The deep fibers of the multifidus muscle and the transverses abdominis co-contract during function. (v) Changes in the lumbar paraspinal muscles associated with low back pain affect the deep fibers of the multifidus muscle more than the superficial fibers of the multifidus muscle or the erector spinae. (21) Architectural analysis and intra-operative measurements demonstrate the unique design of the multifidus muscle for lumbar spine stability. The architectural design (a high cross-sectional area and a low fiber length-to-muscle length ratio) demonstrates that the multifidus muscle is uniquely designed as a stabilizer to produce large forces. Furthermore, multifidus sarcomeres are positioned on the ascending portion of the length-tension curve, allowing the muscle to become stronger as the spine assumes a forward-leaning posture. (22)

The specific stabilizing exercise approach appears to be effective in conservative treatment programs of low back pain and lumbar disk disease. (23) Specific stabilization exercise therapy in addition to medical management and resumption of normal activity may be more effective in reducing low back pain recurrences. (24) Muscle endurance is an important variable to measure in the assessment of back muscle function. The multifidus shows the highest fatigue rate during the trunk holding test, which may be due to the higher activity level of the multifidus muscle during the trunk holding contraction. (25) the static holding component between the concentric and eccentric phase was found to be critical in inducing multifidus muscle hypertrophy during stabilization exercise. Treatment consisting of stabilization training combined with an intensive lumbar dynamic-static strengthening program seems to be the most appropriate method of restoring the size of the multifidus muscle. (26)

It has been questioned whether a patient could achieve proper stabilization and recovery through physical rehabilitation after receiving radiofrequency neurolysis, considering the important role the multifidus muscle plays in spinal and core stabilization. The purpose of this case study is to address this issue of achieving spinal and core stabilization, via chiropractic manipulation and active physical rehabilitation, on a patient who had previously undergone radiofrequency neurolysis.

CASE REPORT
A 25-year-old Caucasian male presented with a chronic 3 year duration low back injury. He complained of pain that originated in his lower back and radiated down his right gluteal region and into the back of his right posterior thigh and lateral calf. He reported his original injury occurred three years ago while at work. The day prior to his injury he had performed an entire day of heavy bending and lifting at work unloading trucks. The following day he was unloading produce from a cooler, was bent over lifting a 50 pound box of lettuce, and felt what he described as an immediate “explosion of pain”, originating in his low back and radiating down his right leg. He stated initially his pain levels were 8 or 9 on the verbal analog scale, and the pain ran from his low back and radiated all the way down to his right foot. Initially he had numbness that encompassed his entire right lower extremity to the foot. The patient reported he was a recovering drug addict, and was not able to take any medications for his injury other than a mild over the counter NSAID.

Initial treatment consisted of NSAID treatment and physical therapy at the industrial medical center. The physical therapy consisted of unsupervised exercises and some stretching. The patient stated his pain levels were so bad at that point in time, that the physical therapy did not help his condition, and in fact seemed to exacerbate his condition. He had an MRI performed which revealed degenerative disc disease, central disc herniations, and facet arthropathy at L4-5 and L5-S1. He went through a second unsuccessful program of physical therapy and was subsequently referred to a pain management specialist. The patient received two sets of 3 epidural blocks, facet injections, and eventually underwent the procedure of radiofrequency neurolysis. The patient stated the blocks and injections helped significantly reduce his pain levels, but the relief was temporary and his symptoms eventually returned. He had radiofrequency neurolysis performed approximately one month prior to entering the chiropractic office, which initially helped reduce his pain about 40%, but his symptoms gradually returned again. He remained unable to return to work from the time of his injury.

The patient was given outcome measures to complete in the office. He rated his lower back pain as 8/10 on the Visual Analog Scale. The Oswestry Disability Index (27,28,29) was 46%, severe disability. The patient reported a history of occasional mild achy low back problems in his past, but no significant low back injuries or trauma prior to his work injury. His past medical history was significant for chemical dependency, chicken pox, mononucleosis, and migraine headaches. He exhibited no red flags (30) to conservative treatment.

The initial examination of this patient included a physical, chiropractic, orthopedic, and neurological examination. The patient was 25 years old, 6 feet 1 inches tall, and weighed 130 pounds. His initial blood pressure was 120/80. Pulse was 80 beats per minute and respirations were 18 per minute. His lumbar range of motion was restricted in flexion 10°/90°; extension 5°/25°; right lateral flexion 10°/25° and left lateral flexion 15°/25°. Manual motor testing was performed on the lower extremities. He exhibited full strength against resistance bilaterally of the hip flexor and extensor muscles; knee extensor and flexor muscles; ankle flexor and extensor muscles; and great toe extensor muscles. Heel walk and toe walk were normal. The patellar and achilles deep tendon reflexes were equal and active bilaterally. Pinwheel sensory test was normal bilaterally for the lower extremities.

Orthopedic examination of the lumbar spine revealed a positive SLR at 55° on the right, producing lower back and right leg pain. Kemps test was positive on the left producing low back pain, and positive on the right producing low back and right leg pain. Hyperextension test was positive producing low back pain, and Spring test was positive for restricted joint motion and pain at the levels L3, L4, and L5.

MRI of the lumbar spine was reviewed. The upper lumbar levels were unremarkable. The L3-4 level showed some slight facet arthrosis. The L4-5 level showed degenerative disc disease and some mild disc space narrowing. Broad based central disc herniation caused some effacement of the ventral aspect of the thecal sac. Facet arthritic changes were present at this level, and combined to produce mild canal stenosis. The foramina appeared patent. The L5-S1 level showed disc degeneration and disc space narrowing as well. There was a central or slightly right central disc herniation present at this level, again causing some mild effacement of the ventral aspect of the thecal sac. The foramen were patent.

The patient was diagnosed with lumbar disc herniation with degenerative disc disease and facet arthropathy. He was treated conservatively in the office with a treatment regimen consisting of passive and active treatment at three times per week for three weeks. He was treated with lumbar spinal manipulation, consisting of flexion distraction manipulation and side posture manipulation, as tolerated by the patient. Additionally, modalities were utilized consisting of interferential current and manual therapy techniques to the lower back region. The patient was instructed in and placed on McKenzie exercises, to be performed at home 10 times per day at 10 repetitions each session.

The patient noted improvement in his lower back and right leg pain over the next three treatments. He had some mild difficulty with low back soreness from the extension component of his exercises, but reported overall improvement. On the fourth visit the patient was instructed in proper abdominal breathing, abdominal bracing, and anterior and posterior pelvic tilting exercises. By the seventh visit the patient reported centralizing of his right leg pain and reduced low back pain to an average pain level 3-4 on the verbal analog scale. The patient was scheduled for a Qualitative Functional Capacity Evaluation for the next visit.

On the eighth visit the patient was cleared with a Physical Activities Readiness Questionnaire, and also read and signed an informed consent to perform the Qualitative Functional Capacity Evaluation. The Qualitative Functional Capacity Evaluation was performed on the patient, consisting of age and gender specific flexibility, strength and endurance testing. The following were his results:

Flexibility Tests Result % of Normal
Sit and Reach - 9 cm Poor
Trunk Extension 15 Poor
Repetitive Tests
Repetitive Squat 40 reps 100+%
Repetitive Sit Up 25 reps 86%
Repetitive Arch Up 9 reps 35%
Endurance Tests
Static Abdominal Hold 55 sec 73%
Static Back Endurance 12 sec 14%
Horizontal Side Bridge 40R 43L 43%R 44%L

Results demonstrated significant deficiencies in strength and endurance of the core and spinal extensor muscles. Of particular importance was the major deficiency in static back endurance and repetitive arch up, which involves primarily the multifidus muscles, along with the iliocostalis and longissimus. Informed consent to begin a physical rehabilitation program was obtained. An in office supervised program of low tech floor exercises was initiated consisting of quadruped alternate arm/leg extensions, horizontal side bridges, curl ups, and sit backs. All exercises were performed with concurrent abdominal bracing. The patient performed these exercises at 3 sets of 10 repetitions, 3 days per week for 4 weeks. Superman and see-saw exercises on a gym ball were initiated on week 5, to further challenge the spinal extensor muscles. Repetitive back extension and lateral trunk flexion exercises were initiated (3 sets of 10) on a Roman Chair on week 8.

The patient was re-evaluated after 90 days on this regimen and achieved the following results:

Flexibility Tests Result % of Normal
Sit and Reach + 12 cm Good
Trunk Extension 30 Good
Strength Tests
Repetitive Squat 45 reps 100%+
Repetitive Sit Up 50+ reps 100%+
Repetitive Arch Up 50+ reps 100%+
Endurance Tests
Static Abdominal Hold 90 sec 100%+
Static Back Endurance 120 sec 100%+
Horizontal Side Bridge 100 R 110 L 100%+ R 100%+ L

Since the follow-up testing, the patient has returned to full time employment and is performing his regular activities of daily living with no restrictions. At the time of reporting this case study, two years post-rehabilitation, no exacerbation or significant recurrence of back or leg pain has occurred. The patient’s pain level has remained at an average 1 or 2 out of 10. His Oswestry Disability Index is 16%, minimal disability. His lumbar range of motion is unrestricted in all planes.

DISCUSSION

It has been questioned whether a patient could achieve proper stabilization and recovery through physical rehabilitation after receiving radiofrequency neurolysis, considering the important role the multifidus muscle plays in stabilization.

In this case study the patient had radiofrequency neurolysis performed prior to his rehabilitation program. Functional performance testing prior to beginning rehabilitation showed major deficiencies in static back endurance and repetitive arch up tests, which involves primarily the multifidus muscles. For this reason, rehabilitation was focused on stabilization and strengthening of the core and spinal stabilization muscles, and was primarily extension based, focusing on the multifidus muscles. Functional performance testing after rehabilitation showed above normal levels in static back endurance and repetitive arch up tests, which would suggest the multifidus muscles were sufficiently strengthened and rehabilitated.

Two-year follow up after completion of his rehabilitation program reveals the patient has not had an exacerbation or significant recurrence of back or leg pain. The Static Back Endurance (Sorenson) test is an excellent predictor of future lower back pain. (31) Asymptomatic individuals with very poor scores are three times more likely to suffer from lower back pain in the next year than those scoring considerably higher. (32) The static back endurance test involves primarily the multifidus muscles. The multifidus muscle activity is critical for normal spinal control, and weakness or dysfunction of the multifidus provides a mechanism for recurrent episodes of low back pain and dysfunction. (18) Lack of multifidus muscle recovery may be one reason for the high recurrence rate of low back pain following the initial episode.(19) These facts combined with the lack of recurrence of back or leg pain in this case suggests that proper multifidus recovery was obtained.

A factor worth taking into consideration in cases such as these is whether the radiofrequency neurolysis procedure completely denervated the multifidus muscle. Studies have shown that occasionally the multifidus is not successfully denervated, as demonstrated by electromyography; Studies have also shown that occasionally the multifidus is successfully denervated, as demonstrated by electromyography, but the Z-joints may be inadequately denervated. (10) Thus, just because the procedure has been performed, it does not necessarily assure the multifidus has been denervated.

The theory also exists that stabilization may occur through compensation by strengthening the uninvolved multifidus muscles, thus achieving overall spinal stability without achieving recovery of the specific level of the involved multifidus. However, recent studies support that the pattern of multifidus muscle atrophy in chronic low back pain patients is also localized rather than generalized. These studies have shown that the pattern of atrophy is both vertebral level and side specific. (14)

CONCLUSION
A patient with a clinical diagnosis of lumbar disc herniation with degenerative disc disease and facet arthropathy, post radiofrequency neurolysis procedure, responded positively to a clinical trial of manipulation and active therapeutic rehabilitation which included flexion distraction, specific adjustments to the lumbar spine, and rehabilitative exercises designed for core and spinal stability. Firm conclusions cannot be derived from the outcomes of a single retrospective case study. However, this study does suggest that chiropractic and rehabilitative care can still relieve lower back and leg pain; symptom recurrence rates can be reduced; and core and spinal stability can still be achieved, despite prior radiofrequency neurolysis procedure having been performed. This study also suggests that prior radiofrequency neurolysis procedure should not be considered a contraindication to chiropractic manipulation and rehabilitation. Additional studies need to be completed, using more specific techniques and measures: such as measuring cross sectional areas and performing electromyography of the specific involved multifidus muscles, both pre and post rehabilitation, to specifically determine if actual multifidus recovery is obtained through specific treatment protocols.

REFERENCES:

1. Carey TS, Evans AT, Hadler NM, Lieberman G, Kalsbeek WD, Jackman AM, Fryer JG and McNutt RA. Acute severe low back pain: A population-based study of prevalence and care-seeking. Spine 21:339-344, 1996

2. Frymoyer JW, Cats-Baril W. Predictors of low back pain disability. Clinical Orthopedics and Related Research 221:89-98, 1987

3. VonKorff & Saunders. The course of back pain in primary care. Spine 1996; vol 21(24): 2833-2839.

4. Jayson. Presidential Address. Why does acute back pain become chronic? Spine 1997; vol 22(10)

5. Holbrook TL, Grazier K, Kelsey JL, Stauffer RN. The frequency of occurrence, impact and cost of selected musculoskeletal conditions in the United States. American Academy of Orthopaedic Surgeons, Chicago, IL, 1984

6. Waddell G. Epidemiology review: The epidemiology and cost of back pain. The Annex to the Clinical Standards Advisory Group’s Report on Back Pain. London: HSMO, May 1994

7. Waddell G. The Back Pain Revolution. Edinburgh: Churchill Livingstone, 1998.

8. Dreyfuss P, Halbrook B, Pauza K, Joshi A, Mclarty J, Bogduk N. Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapopysial joint pain. Spine 2000 May 15; 25(10): 1270-7.

9. Sihvonen T, Lindgren KA, Airaksinen O, Leino E, Partanen J, Hanninen O. Dorsal ramus irritation associated with recurrent low back pain and its relief with local anesthetic or training therapy. J Spinal Disord. 1995 Feb;8(1): 8-14.

10. Windsor RE. Radiofrequency lumbar zygapophysial (facet) join denervation: a preliminary report of a new concept. Pain Physician. 2003 Jan; 6(1): 119-23.

11. Hyun JK, Lee JY, Lee SJ, Jeon JY. Asymmetric atrophy of multifidus muscle in patients with unilateral lumbosacral radiculopathy. Spine. 2007 Oct 1; 32(21): E598-602.

12. Hodges P, Holm AK, Hansson T, Holm S. Rapid atrophy of the lumbar multifidus follows experimental disc or nerve root injury. Spine. 2006 Dec 1; 31(25): 2926-33.

13. Hides JA, Stokes MJ, Saide M, Jull GA, Cooper DH. Evidence of lumbar multifidus muscle wasting ipsilateral to symptoms in patients with acute/subacute low back pain. Spine. 1994 Jan 15; 19(2): 165-72.

14. Hides J, Gilmore C, Stanton W, Bohlscheid E. Multifidus size and symmetry among chronic LBP and healthy asymptomatic subjects. Man Ther. 2008 Feb; 13(1): 43-9.

15. Wallwork TL, Stanton WR, Freke M, Hides JA. The effect of chronic low back pain on size and contraction of the lumbar multifidus muscle. Man Ther. 2008 Nov 20.

16. Cornwall J, John Harris A, Mercer SR. The lumbar multifidus muscle and patterns of pain. Man Ther. 2006 Feb; 11(1): 40-5.

17. Kader DF, Wardlaw D, Smith FW. Correlation between the MRI changes in the lumbar multifidus muscles and leg pain. Clin Radiol. 2000 Feb; 55(2): 145-9.

18. MacDonald D, Moseley GL, Hodges PW. Why do some patients keep hurting their back? Evidence of ongoing back muscle dysfunction during remission from recurrent back pain. Pain. 2009 Apr; 142(3): 183-8.

19. Hides JA, Richardson CA, Jull GA. Multifidus muscle recovery is not automatic after resolution of acute, first-episode low back pain. Spine. 1996 Dec 1; 21(23): 2763-9.

20. Hides JA, Stanton WR, McMahon S, Sims K, Richardson CA. Effect of stabilization training on multifidus muscle cross-sectional area among young elite cricketers with low back pain. J Orthop Sports Phys Ther. 2008 Mar; 38(3): 101-8.

21. MacDonald DA, Moseley GL, Hodges PW. The lumbar multifidus: does the evidence support clinical beliefs? Man Ther. 2006 Nov; 11(4): 254-63.

22. Ward SR, Kim CW, Eng CM, Gottschalk LJ 4th, Tomiya A, Garfin SR, Lieber RL. Architectural analysis and intraoperative measurements demonstrate the unique design of the multifidus muscle for lumbar spine stability. J Bone Joint Surg Am. 2009 Jan;91(1):176-85.

23. Kladny B, Fischer FC, Haase I. Evaluation of specific stabilizing exercise int eht treatment of low back pain and lumbar disk disease in outpatient rehabilitation. Z Orthop Ihre Grenzgeb. 2003 Jul-Aug; 141(4): 401-5.

24. Hides JA, Jull GA, Richardson CA. Long term effects of specific stabilizing exercises for first-episode low back pain. Spine. 2001 Jun 1:26(11):E243-8.

25. Ng JK, Richardson CA, Jull GA. Electromyographic amplitude and frequency changes in the iliocostalis lumborum and multifidus muscles during a trunk holding test. Phys Ther. 1997 Sept;77(9):954-61.

26. Danneels LA, Vanderstraeten GG, Cambier DC, Witvrouw EE, Bougois J, Dankaerts W, De Cuyper HJ. Effects of three different training modalities on the cross sectional area of the lumbar multifidus muscle in patients with chronic low back pain. Br J Sports Med. 2001 Jun;35(3):186-91.

27. Von Korff M., Deyo RA, Cherkin D, Barlow W. Back pain in primary care: Outcomes at 1 year. Spine, 1993, 18, 855-862. Oswestry Disability Index

28. Fairbank J, Davies J, et al. The Oswestry Low Back Pain Disability Questionnaire. Physiotherapy, 1980, 66 (18), 271-273

29. Hudson-Cook N, Tomes-Nicholson K. The Revised Oswestry Low Back Pain Disability Questionnaire. Thesis, Anglo-European College of Chiropractic, 1988

30. Klassen AC, Berman ME. Medical care for headaches. A consumer survey. Cephalgia 1991:11 (supp 11) 85-86.

31. Biering-Sorensen F. Physical measurements as risk indicators for low back trouble over a one-year period. Spine 1984; 9: 106-119.

32. Luoto S, Hiliovaara M, Hurri H, Alaranta H. Static back endurance and the risk of low back pain. Clin Biomech 1995; 10: 323-324.