[ Pain or NO: The Research | Classifications | Diagnostic Techniques | Slide Show ]

GENERAL INFORMATION:

The term "Spondylolisthesis" refers to a condition where one of the vertebrae (usually L5) becomes misaligned anteriorly (slips forward) in relation to the vertebra below. This forward slippage is caused by a problem or defect within the pars interarticularis (aka: pars), facet joint(s) or neural arch of the effected vertebra. The forward slippage does NOT always occur; however, the par defect, which is considered a non-united childhood fracture by some (134), still may be present. This non-slipped pars defect is called a "Spondylolysis."

The aforementioned structures are responsible for holding the vertebrae of the spine in perfect alignment. Maintaining this alignment is critical in order to keep the spinal exit-holes, (aka: neuroforamen), which are where the delicate spinal nerves exit the spine, large and open. Any narrowing of the neuroforamen may result in compression of the ultra-sensitive exiting spinal nerve root and dorsal root ganglia that in turn may well result in back pain. (Fig.#1)

The pars interarticularis, which is the weakest and thinnest region of the vertebra, may only be able to tolerate the 'activities of daily living' in some individuals (135) and is easily fracturable with repeated loaded-flexion (136) and axial rotation. (139)

In figure #1, the 'pink' region of the vertebrae represents the area of the neural arch known as the "pars interarticularis" or "pars" for short.

Professor Nikolai Bogduk, who is the number 1 functional anatomist in the world and a two time Volvo Award Winner, has the following opinion on the origin of spondylolysis: "The biomechanical and epidemiological evidence points to pars defects being an acquired fracture, either as a result of single, severe trauma or as a result of fatigue failure." (136,138,150,152,153)[126]

It also appears that about 1/2 of these pars fracture occurs in childhood (8) and later, in adulthood, become symptomatic. More explicitly, in the late 1950's Fredrickson et al. prospectively X-rayed 500 asymptomatic first-grade students in attempts to identify the prevalence rate for spondylolisthesis and spondylolysis. The prevalence rate that was discovered in this pain-free group of kids (aka: occurrence rate) was 4.4% at age 6. This increased to 6% in adulthood. The authors concluded that progression of "slip" was "unlikely" after adolescents. (8)

In spondylolisthesis or spondylolysis, a "fibrous tissue" will form within the crack (defect) within the pars. (131) This "fibrous tissue" contains nerve fiber and pain-carrying free nerve endings (133) that contain neuropeptides (134); therefore, this tissue is theoretically capable of transmitting PAIN-signals to the brain [in layman's terms: this scar tissue like stuff that fills the crack in the back bone, has the potential to cause back pain.]

Fig. #2 represents a grade I Isthmic spondylolisthesis, which is the most common form of spondylolisthesis in people under 50 years of age (40). About 90% of these spondylolisthesis' occur at the L5 vertebral level (37). The prevalence rate (rate naturally occurring in a given population) of spondylolysis in the general population is about 7% (502); however, in Alaskan Eskimos the prevalence rate is between 28% (11) and 40%! (10)

In Fig. #2 you can see that a "crack" or "pars defect" that has occurred within the pars interarticularis of the L5 neural arch. Because of the defect, the L5 vertebral body has slid forward by about 25% as measured against the sacral base below; anterior translation has occurred. This condition is called a "spondylolytic spondylolisthesis."

Also notice that the exiting L5 spinal nerve root has become compressed by the translating vertebral column and is red with inflammation. If severely symptomatic, a surgical procedure called a Fusion (LAIF or PLIF) may be indicated to realign the vertebrae and restore the neural foramen to their original size.

In real life, the large and jagged "pars defect" is filled with a fibrous tissue that is, unfortunately, filled with nerve fiber. (133,134)

DOES SPONDYLOLYSIS / SPONDYLOLISTHESIS CAUSE PAIN: THE RESEARCH?

It is common knowledge that spondylolysis and spondylolisthesis are seen with equal frequency in both asymptomatic people and symptomatic people (501,512), and the degree of forward slippage is in no way correlated with the degree of patient pain or disability. (16,46)

More explicitly, in 1982 Libson and Dinari radiographically studied the occurrence rate (prevalence) of spondylolysis / spondylolisthesis in 936 asymptomatic (pain free) and 662 symptomatic (back pain suffering) military soldiers concurrently. They discovered that just as many pain-free soldiers had spondylolysis and/or spondylolisthesis on X-ray as did the soldiers who had symptomatic back pain, i.e., 10% of the asymptomatic soldiers and 9% of the symptomatic soldiers had spondylolysis/spondylolisthesis on radiograph. (501)

Other investigators have confirmed the prevalence rates in the aforementioned findings in pain-free people:

Recently, in 2005 Beck et al. published the results of a very large investigation into the prevalence of spinal anomalies in patients with back pain. After studying the radiographs of 1004 patients presenting to a New Zealand chiropractic clinic for back pain, 7.8% had spondylolisthesis. (502)

In 1966 a famous and often quoted investigation by Moreton investigated the prevalence (occurrence rate) of spondylolysis within 32,600 asymptomatic people who were X-rayed as part of a pre-employment screening. The prevalence of spondylolysis in this group of 18 to 35 year olds was 7.2%. (503) Other investigation have concluded this same prevalence rate. (8,512)

The aforementioned investigation (512), prompted Professor Nikolai Bogduk, MD, researcher, author, and two-time Volvo Award winner to proclaim within the ‘Australasian Faculty of Musculoskeletal Medicine Guidelines’ that “finding a pars defect on a plain film does not constitute establishing a diagnosis of the patient's pain.” (500) Two other research giants, Schmorl and Junghans, have also proclaimed that pain specifically related to spondylolysis and/or spondylolisthesis does not exist. (27)

However, in either spondylolisthesis or spondylolysis, the fibrous-filled defect that forms within the pars (131) certainly has the potential to generate back pain, for it contains both nerve fiber and pain-carrying free-nerve endings (133) that contain neuropeptides (134).

CLASSIFICATION OF SPONDYLOLISTHESIS:

The most widely used classification system was developed by Wiltse et al. back in 1976 (36) This system described five distinct types of spondylolisthesis:

1.) Dysplastic Spondylolisthesis: Congenital malformation of the sacrum or neural arch of L5.

2.) Isthmic Spondylolisthesis: Stress fracture, elongation, or acute fracture of the pars.

3.) Degenerative Spondylolisthesis: Long-standing arthritic process of the zygapophyseal joints.

4.) Traumatic Spondylolisthesis: Neural arch fracture excluding the pars region.

5.) Pathologic Spondylolisthesis: Bone disease - Paget's, Metastatic disease, or Osteopetrosis.

6.) Iatrogenic Spondylolisthesis: Man-made following lumbar spine surgery via LAIF or Laminectomy.

Now, let us look at the more common forms of spondylolisthesis:

DYSPLASTIC SPONDYLOLISTHESIS: (aka: Congenital Spondylolisthesis)

This type of spondylolisthesis results from a congenital (from birth) malformation (aka: dysplasia or defective growth/development) of the neural arch of the vertebra and/or upper portion of the sacrum. More explicitly, the articular processes of the vertebrae are tipped too far forward, the facet joints are facing forward (sagittal or axial) instead of sideways (coronal), and/or there is a malformed sacrum with spina bifida that allows spondylolisthesis.

Although fairly rare, 14-21% of all discovered spondylolisthesis are the result of the the aforementioned congenital malformations. (1) Isthmic spondylolisthesis, however, is four times more common. (40) When dysplastic spondylolisthesis occurs, it's usually quite severe. (40)

Unlike the other forms of spondylolisthesis, the dysplastic variety has a possible genetic predisposition. More explicitly, Wynne-Davies et al. (2) X-rayed 147 first-degree relatives of patients with spondylolisthesis. The results indicated that 33% of the relatives also, unknowingly, had dysplastic spondylolisthesis. This is four-time higher than what would be expected in the normal population where 8% is the population prevalence for spondylolisthesis. (500,501,502,512) Other investigators have also reported a familial predisposition as well (3).

ISTHMIC SPONDYLOLISTHESIS: (aka: Lytic Spondylolisthesis)

In people under the age of 50, Isthmic spondylolisthesis is the number one type of spondylolisthesis encountered and has not been noted in infants (40). The reported prevalence rate (how frequently seen) in the US population is between 6% and 7% (5), although its X-ray presents is certainly not always associated with back pain. (500,501,502,512) There are three "sub-types" within this category:

SUB-TYPE A: (aka: Lytic Spondylolisthesis)

Sub-Type A is the most commonly found type of spondylolisthesis in people under 50 years of age (40). It is believed that "biomechanical stress," such as repetitive mechanical strain from heavy work or sports, causes a fatigue fracture within the pars interarticularis (26) that in turns allows the defective vertebra to move forward in relationship to the sacrum or vertebra below. There does, however, seem to be a familial predisposition for Isthmic spondylolisthesis, for 15% of first-degree relatives of people with Isthmic spondylolisthesis will also have spondylolisthesis (2); this 15% prevalence is double the natural occurrence rate of spondylolisthesis of 6-7%. (501,502,512)

In a recent clinical guideline, Dr. Nikolai Bogduk MD, PhD, author, and Volvo Award Winner, stated, “The biomechanical and epidemiological evidence points to pars defects being an acquired fracture, either as a result of single severe trauma or as a result of fatigue failure (19,21,32,34,35).” (500) “The fibrous tissue that fills the defect may contain osseous debris that is evidence of its traumatic origin (17).”

SUB-TYPE B:

This type of Isthmic spondylolisthesis is characterized by a elongated pars without separation. It is believed that the elongation occurs secondary to "repeated, minor trabecular stress fractures of the pars." (26) Each time these possible sub-acute stress fractures occur and heal, the vertebral body is displaced farther and farther forward. Eventually, the pars may fail to heal and result as a full pars defect; therefore, it may be impossible to differentiate between Sub-Type A and Sub-Type B categories.

SUB-TYPE C:

These types of spondylolisthesis' are extremely rare and result from an acute pars fracture, often as result of traumatic lumbar hyperextension injury; displacement seldom occurs. (39)

DEGENERATIVE SPONDYLOLISTHESIS: (aka: Pseudospondylolisthesis, nonspondylolytic spondylolisthesis)

This is the most common form of spondylolisthesis in patients over 50 years of age and rarely occurs in those under 50. There is no fracture or elongation of the pars interarticularis and the neural arch is intact. The mechanisms of forward displacement are thought to involve a combination of "zygapophyseal joint arthrosis, disc degeneration, and remodeling of the articular processes and pars." (26,41) On X-ray, a widened "Pedicle-facet angle" is one of the tell-tale signs of degenerative spondylolisthesis. Finally, so some strange reason, Degenerative Spondylolisthesis has an affinity for affecting Females, at L4, who are over 40. [The 3 F's of degenerative spondylolisthesis.]

TRAUMATIC SPONDYLOLISTHESIS:

This type of spondylolisthesis, which is extremely rare, results from a traumatically-induced fracture to the neural arch other than the pars region. The "Hangman's Fracture" in the cervical spine's second vertebra (Axis) is a common and often deadly example of such a traumatically induced phenomenon. This type of fracture is extremely rare in the lumbar spine.

PATHOLOGICAL SPONDYLOLISTHESIS:

Generalized or systemic disorders of bone may affect the neural arch of the spine and allow spondylolysis or spondylolisthesis to occur. Metastatic carcinoma (cancer), osteopetrosis, and Paget's disease are some of the more common disorders that may contribute to the formation of spondylolysis. (26)

IATROGENIC SPONDYLOLISTHESIS:

Iatrogenic (man-made) spondylolisthesis is a complication of lumbar anterior interbody fusion (LAIF), which ironically is often used to stabilize spondylolisthesis. Either the vertebrae above of below develops a pars fracture and possibly forward slippage from the extra stress placed upon that segment from the surgery. Laminectomy procedures, which are used for decompressing symptomatic disc herniations in the spine, will result in an overload of weight-bearing stress on the contralateral pars and, in some patients, result in a pars fracture.

DIAGNOSTIC TECHNIQUES:

In 1994 Suh et al. described a technique for differentiating between a symptomatic pars defect and non-symptomatic pars defect. They simply anesthetized the suspect with lidocaine to see if this affected the patients pain. If so, then the pars was named a pain-generator and surgery proceeded. (154)

Bogduk also described this 'pars block' in his recent book entitled "Medical Management of Acute and Chronic Low Back Pain." More explicitly, Bogduk stated the following: "The definitive test of whether a pars defect is symptomatic is to anaesthetise the [pars] defect. (154) Pars blocks are the only means available by which to determine whether or not a radiographically evident defect is a symptomatic or an asymptomatic one. Such a test is imperative in view of the high prevalence of defects in asymptomatic individuals." (126)

REFERENCES:

1) Leone LD, Lamont DW. “Diagnosis and treatment of severe dysplastic spondylolisthesis.” J AM Osteopath Assoc 1999;99:326-8

2) Wynne-Davies R, Scott JHS. “Inheritance and spondylolisthesis – a radiographic family survey.” J Bone Joint Surg Br 1997;618:301-5

3) Saha MM, et al. "Osteopetrosis with spondylolysis: four cases in one family." Br Radiol 43:738, 1970.

5) Wiltse LL. "Spondylolisthesis: Classification and Etiology." Symposium of the Spine, Am Acad Orthop Surg 1969; 143.

7) Batts M Jr. "The etiology of Spondylolisthesis." J Bone Joint Surg (Am) 21:879, 1939

8) Fredrickson BE, et al. "The Natural History of spondylolysis and spondylolisthesis." J Bone Joint Surg (Am) 66:699 1984 "We performed a prospective roentgenographic study to determine the incidence of spondylolysis, spondylolisthesis, or both, in 500 unselected first-grade children from 1955 through 1957. The families of the children with spondylolysis were followed in a similar manner. The incidence of spondylolysis at the age of six years was 4.4 per cent and increased to 6 per cent in adulthood. The degree of spondylolisthesis was as much as 28 per cent, and progression of the olisthesis was unusual. The data support the hypothesis that the spondylolytic defect is the result of a defect in the cartilaginous anlage of a vertebra. There is a hereditary pre-disposition to the defect and a strong association with spina bifida occulta. Progression of a slip was unlikely after adolescence and the slip was never symptomatic in the population that we studied."

10) Stewart TD. "The Age Incidence of Neural Arch Defects in Alaskan Natives, Considered from the Stand Point of Etiology." J Bone Joint Surg (Am) 1953; 35:937

11) Kettelkamp DB, Wright DG. "Spondylolysis in the Alaskan Eskimo." J Bone Joint Surg (Am) 1971; 53:563.

16) Turner RH, Bianco AJ. "Spondylolysis and Spondylolisthesis in Children and Teenagers." J Bone Joint Surg (Am) 53:1298, 1971

17) Eisenstein SM, Ashton IK, Roberts S, Darby AJ, Kanse P, Menage J, Evans H. Innervation of the spondylolysis "ligament". Spine 1994; 19: 912-916.

19) Cyron BM, Hutton WC. The fatigue strength of the lumbar neural arch in spondylolysis. J Bone Joint Surg 1978; 60B: 234-238.

26) Yochum TR, Rowe LJ. "Essentials of Skeletal Radiology" Baltimore; Williams & Wilkins; second edition: 1996:

27) Schmorl G, Junghans H. "The human Spine in Health and Disease, ed 2. New York, Grune & Stratton, 1971

31) Rowe GG, Roche MB. The etiology of separate neural arch. J Bone Joint Surg 1953; 35A: 102-110.

32) Hensinger RN. Spondylolysis and spondylolisthesis in children and adolescents. J Bone Joint Surg 1989; 71A: 1089-1107.

34) O'Neill DB, Micheli LJ. Postoperative radiographic evidence for fatigue fracture as the etiology in spondylolysis. Spine 1989; 14: 1342-1355.

35) Wiltse LL, Widell EH, Jackson DW. Fatigue fracture: the basic lesion in isthmic spondylolisthesis. J Bone Joint Surg 1975; 57A: 17-22.

36) Wiltse LL, Newman PH, Macnab I. "Classification of spondylolysis and spondylolisthesis." Clin Orthop Relat Res. 1976 Jun;(117):23-9.

37) McKee BM, et al. "Spondylolysis and spondylolisthesis in Children: A Review." J Can Assoc Radiol 1971; 22:100

39) Wiltse LL, et al. "Classification of spondylolysis and spondylolisthesis." Clin Orthop 117:23, 1976

40) Moe JH, et al. "Scoliosis and other Spinal Deformities," Philadelphia, WB Saunders, 1978.

41) Macnab I. "Spondylolisthesis with intact an intact neural arch-so called pseudospondylolisthesis." J Bone Joint Surg (Br) 32:325,1950

46) Friberg S. "Studies on Spondylolisthesis." Acta Chir Scand 82(Suppl):55, 1939.

126) Bogduk N, McGuik B. "Medical Management of Acute & Chronic Low Back Pain." vol 13 Amsterdam; Elservier: 2002

131) Roche MB. "The pathology of Neural-Arch Defects." J Bone Joint Surg 1949: 31A: 529-537

132) Ghelman B, Doherty JH. "Demonstration of Spondylolysis by Arthrography of the Apophyseal Joint." Am J Roentgenol 1978; 130:986-987

133) Schneiderman GA, et al. "The Pars Defect as a Pain Source: a Histological Study." Spine 1995; 20:1761-1764. "CONCLUSIONS. Free nerve endings believed to have nociceptive function were identified in all specimens. The finding of neural elements, including free nerve endings within the pars defect tissue, suggests that the pars defect may be a source of back pain in some patients with symptomatic spondylolysis."

134) Eisenstein SM, et al. "Innervation of the Spondylolysis 'Ligament'. Spine 1994; 19:912-916. "CONCLUSION. Spondylolysis of the lower lumbar vertebrae is a non-united childhood fracture of the arch of the vertebra, persisting into adult life. Symptoms of disabling low back pain appear in a minority of patients, usually for the first time in adulthood. This pain is considered to arise from several separate sources, one of which may be the spondylolysis ligament. The movement that the ligament allows at the fracture site may result in stimulation of the nerve endings both in the ligament and in the surrounding soft tissue."

135) Cyron BM, Hutton WC. "Variations in the amount and Distribution of Cortical Bone Across the Partes Interarticulares of L5. A predisposing Factor in Spondylolysis?" Spine 1979; 4: 163-167

136) Cyron BM, Hutton WC. "The Fatigue Strength of the Lumbar Neural Arch in Spondylolysis." J Bone Joint Surgery 1978: 60B:234-238.

138) Green TP, et al. "Spondylolysis: Bending of the Interior Articular Processes of Lumbar Vertebrae during Simulated Spinal Movements." Spine 1994; 19: 2683-2691.

139) Farfan HF, et al. "The Effects of Torsion on the Lumbar Intervertebral Joints: The role of Torsion in the production of Disc Degeneration." J Bone Joint Surg 1970; 52A: 468-497

150) Hensinger RN. "Spondylolysis and Spondylolisthesis in Children and adolescents." J Bone Joint Surg 1989; 71A:1089-1107

152) O'Neil DB, Micheli LJ. "Postoperative Radiographic Evidence for Fatigue Fracture as the Etiology in Spondylolysis." Spine 1989; 14:1342-1355

153) Wiltse LL, et al. "Fatigue Fracture: the Basic Lesion in Isthmic Spondylolisthesis." J Bone Joint Surg 1975; 57A: 17-22

154) Suh PB, Esses SI, Kostuik JP. "Repair of pars interarticularis defect. The prognostic value of pars infiltration." Spine. 1991; 16(8 Suppl):S445-8. "Ten patients with symptomatic spondylolysis or Grade I spondylolisthesis were treated with the Buck method. At follow-up, nine patients were graded as successful. All patients fused. Pain relief, level of function, and likelihood of return to work were higher in patients preoperatively selected by lidocaine infiltration of the pars defect. Pars infiltration gives an accurate prediction of successful outcome following pars repair."

500) Professor Nikolai Bogduk, MD, Multiple Volvo Award Winner ‘Evidence-Based Clinical Guidelines for the Management of Acute Low Back Pain’ The Australasian Faculty of Musculoskeletal Medicine November 1999; Chapter 9

501) Libson E, Bloom RA, Dinari G. Symptomatic and asymptomatic spondylolysis and spondylolisthesis in young adults. Int Orthop 1982;6:259-261.

502) Beck RW, Holt KR, et al. "Radiographic anomalies that may alter chiropractic intervention strategies found in a New Zealand population." J Manipulative Physiol Ther. 2004 Nov-Dec;27(9):554-9. Conclusions: " Eight hundred forty-seven full-spine radiographs were included in the study. Anomalies were found in 68% of patients who had radiographs taken. The 5 most frequently occurring anomalies in descending order were degenerative joint disease (23.8%), posterior ponticle (13.6%), soft tissue abnormalities (13.5%), transitional segments (9.8%), and spondylolisthesis (7.8%). Other noteworthy occurrences because of their generalized status as absolute contraindications to adjustment are fracture (6.6%), malignant tumor (0.8%-3.1%), abdominal aortic aneurysm (0.8%) and atlantoaxial instability (0.6%)."

503) Moreton RD. "Spondylolysis." JAMA. 1966 Feb 21;195(8):671-4. " In 32,600 asymptomatic adults, the prevalence of a pars defect was found to be 7.2%."

512) Jensen MC, et al. “MRI imaging of the lumbar spine in people without back pain.” N Engl J Med – 1994; 331:369-373

SPONDYLOLISTHESIS SLIDE-SHOW: