Lumbar Facet Syndrome
Zygapophysial Joints (ZGAs) in Lumbar Spine
International Publicized Data
GMCD Instructional Course Lectures
Relying on the work of giants is the lifeblood of scientific research. Indeed, if I have seen further, it is by standing on the shoulders of giants. One might even say that I have always depended on the kindness of strangers in this regard (*).
The continuous support by professor BA Kakulas (Neuropathology), professor JR Taylor (Spinal Anatomy and Human Biology), and Sir George M Bedbrook (Spinal Orthopaedic and Rehabilitation Surgeon) made it possible to analyse 23539 post-mortem human spines, normal and pathological, in the Department of Neuropathology, Royal Perth Hospital/University Western Australia, Perth.
Note: in order not to disturb easy reading of the underneath scientifically based chapters, only a few authors are mentioned in the text where dr. Guy considered it essential. Their names are placed between brackets. Further information on their individual research can be read in the last chapter ‘Literature Encyclopedia’.
(*) Mirsky Steve. Copy That. Technology is making it harder for word thieves to earn outrageous fortunes.
Scientific American, February 2014, p.64
Table of Contents
1. Greek term ‘zygapophysial’ (ZGA) joint
‘Zygos’ in Greek means bridge and ‘apophysis’ signifies outgrowth. The spinal ‘bridging outgrowths’ form the posteriorly located articulations between two adjacent vertebrae (Fig. 1a, 1b, 1c) and are called the zygapophysial joints (ZGAs). The shorter term, ‘apophyseal’ joint, is an acceptable term and used regularly.
Because the ZGAs contain various intra-articular facets, each responsible for a particular functional aspect of the ZGA, describing a ZGA joint simply as a ‘facet’ joint is incorrect and too simplistic. Most joints in the human body are multifaceted but all have been well defined with simple names (e.a. knee, ankle, elbow, wrist joint etc…). As there is no rational reason to discard the original Greek term, zygapophysial will be respected in the underneath text.
Fig. 1a. (Left): radiological images of the L3-L4, L4-L5, and L5-S1 ZGA joints (X90-879)
Fig. 1b. (Middle): anatomical views of the L3-L4, L4-L5, and L5-S1 ZGA joints (X90-879)
Fig. 1c. (Right): sagittal view at L1 and L2 pedicular levels with T12-L1 and L1-L2 ZGA joints (X90-879)
2. ZGA joint: hyaline cartilage and synovial lining
Each ZGA joint is composed by two posterior articular processes (= ‘outgrowths’) of two consecutive vertebrae (Fig. 2a, 2b). The superior articular process (SAP) embraces the inferior articular process (IAP). The diarthrodial joint is coated with hyaline articular cartilage and lined with synovium. Like any other synovial joint, the ZGA will undergo the normal course of aging. When degeneration starts, the initial arthritic changes are mostly seen at the proximal and distal ends of the processes because the tips of the ZGAs have no cartilage.
Fig. 2a. (Left) and Fig. 2b. (Right): the zygapophysial joint is a diarthrodial and synovial joint. It is well-coated with articular hyaline cartilage (white zone). The tips of the superior articular process (SAP) and inferior articular process (IAP) have no cartilage. The anteromedial part is not covered by fibrous capsular tissue but by the ligamentum flavum (LF). NR = nerve root. VB = vertebral body
3. Capsule of ZGA joint
The ZGA joint is not circumferentially surrounded by a fibrous capsule. The capsule is thick in its posterior and lateral aspects. The anteromedial part of the ZGA near the spinal canal is not closed by fibrous tissue but replaced by the ligamentum flavum which is in direct contact with the synovium in the ZGA joint (Fig. 2b).
4. Normal anatomic openings in the capsule
At the superior and inferior parts of the ZGA joints, the capsule forms small but normal anatomic openings through which extracapsular adipose tissue moves in and out the joints during the lumbar spinal movements. During the performance of an arthrogram, these normal openings provide a direct route for extravasation of dye into the epidural space. When too much contrast is injected in a ZGA (2 ml or more), the dye always will leak through these normal anatomic holes making the physician incorrectly conclude to a ‘rupture’ of the joint capsule (Fig. 4a, 4b, 4c).
Fig. 4a. (Left): during spinal movements, fat tissue (yellow) moves in an out through normal superior and inferior anatomical openings in the capsule of the ZGA joint
Fig. 4b. (Middle): Author’s conception of an injection of too much blue dye into a ZGA (2 cc or more) resulting in ‘leakages’ through the normal anatomic openings
Fig. 4c. (Right): radiological visualisation of leakages through a normal inferior anatomic opening
5. ZGA joint: shape and orientation of its facets
The shape and orientation of the planes of the articular facets in the ZGA joints determine the relative movements allowed by these joints (Fig. 5a, 5b). The anterior frontally oriented third of the ZGA resists flexion, whereas the posterior sagittally oriented component limits anteroposterior shear movements. As one moves caudally through the lower lumbar levels (L3-L4, L4-L5, L5-S1), a change in the orientation of the articular facets of the ZGAs becomes clear.
Fig. 5a. (Left): T12-L1 ZGA joint in the axial plane. The surface of the superior articular process (SAP) is concave and projects posteromedially. The surface of the inferior articular process (IAP) is convex and directs anterolaterally. There exists a rounded ‘angle’ (more than 90°) between the horizontal and a sagittal components. At the higher lumbar levels (T12-L1, L1-L2, L2-L3) the sagittal orientation is more prominent
Fig. 5b. (Right): Axial view of a L5-S1 ZGA joint. The ZGA becomes less ‘angled’ as the horizontal component becomes more prominent. Note the asymmetry between both ZGAs at the same level
6. Lumbar ZGA joints: orientation varies
Considering the average angle to the sagittal plane (Fig. 6a, 6b), an increase of that angle is clearly distinguished from the T12-L1 vertebral level down to the L5-S1 lumbosacral level. The angle can vary enormously: between 70° and 80° at L3-4, between 80° and 90° at L4-L5, and even over 100° at L5-S1 levels.
Fig. 6a. (Left): orientation of a ZGA joints in the lumbar spine, (Middle): in the thoracic spine, and (Right) in the cervical spines
Fig. 6b. Orientation of the ZGA joints. If oriented 45° to the sagittal axis (red line) there is resistance to forward displacement and rotation. If oriented 0° to the sagittal axis, the ZGA strongly resists rotation. If oriented 90°, there is a strong resistance to forward displacement
7. Bilateral asymmetry (tropism) and its significance
The three-dimensional construction of both ZGA joints at the same lumbar level varies as well. In about 50 % of individuals an average asymmetry varying from 10° to 42° can be measured between left and right ZGAs (Fig. 7a). A difference of 5 degrees or more at one particular lumbar level represents articular tropism.
Tropism strongly suggests the existence of irregular movements. Asymmetry between the ZGAs may lead to increased rotatory hypermobility and torsional strain on the intervertebral disc accelerating the degenerative processes in the nucleus pulposus and creating more annular tears. However, no association has been shown between ZGA joint asymmetry at one particular level and the production of a nuclear herniating pathway at the same level (protrusion, extrusion, or sequestration).
Fig. 7a. Asymmetry of 5° or more between the two ZGA joints at the same lumbar level is called tropism and may lead to rotatory hypermobility
8. Interrelation: intervertebral disc and ZGA joints
The stability and the flexibility of the lumbar spinal column is provided by interaction between the intervertebral discs (IVDs) in the anterior spinal column and zygapophysial joints in the posterior column (Fig. 8a). But as age advances, degenerative processes usually occur in the IVD and subsequently in the ZGA joints. As can be noted on CAT and MRI and has been confirmed by post-mortem analyses: ‘discs degenerate before ZGA joints’.
Fig. 8a. Intervertebral discs and ZGA joints interact for spinal stability and flexibility
9. Essentials on the degenerative discogenic processes
The progress of degenerative processes in the lumbar IVDs leads to the decrease of the hydrostatic pressure resulting in disruption of disc tissues. At the upper lumbar L1-L2 and L2-3 levels, the depressurisation rather occurs in the presence of or is associated with endplate erosions. At the lower lumbar levels, the decrease in nuclear pressure rather leads to the transmission of higher compression loads and an increased concentration of compressive stress into the posterior portions of the annulus. Indeed, the prevalence of annular tears is much higher at the L4-L5 and L5-S1 disc levels. However, it is evident that ruptures of the endplates and the annuli can be present at the same time (Fig. 9a). These disruptions in the disc mostly occur in the sitting, standing, or bending posture. Each of these alterations is considered to initiate (chronic) low back pain.
Fig. 9a. The L4-5 intervertebral disc level (A90/139) presents degenerative internal nuclear disruption, degenerative endplate fissures, anterior and posterior annular bulging, disc height narrowing and osteoporotic vertebral bone
10. ZGA joints: stabilising role
The stabilizing role of the ZGA joints is clearly shown during in vitro experiments and following inadvertent and inappropriate surgery. Partial removal or total resection of the ZGA joints, unilaterally or bilaterally, induce a significant non-physiological segmental range of motion in axial rotation and anteroposterior sagittal translation (Fig. 10a).
Fig. 10a. Inappropriate (surgical) removal of parts of the ZGA joints induce abnormal intervertebral hypermobilities in different directions (red lines)
11. ZGA joints: load sharing structures
Body weight is carried by the vertebral bodies and the adjacent pedicles. In the non-degenerative and healthy lordotic lumbar spine, the axial compressive loads between two vertebral bodies are transmitted by the endplate, nucleus and annulus of the intervertebral discs. Axial compressive loading between the adjacent pedicles is transferred by the ZGAs. The percentage of transmitted load depends on (1) the spinal posture, (2) the degree of intervertebral disc degeneration, and (3) the orientation of the facets in the ZGA joints. In the upright standing position 10 % to a maximum of 20 % of body weight is carried by the ZGAs (measured by mathematical and in vitro models). During increasing hyperextension, more load is transmitted through bony contact at the tips of the inferior articular processes (IAP) with the laminae of the vertebra below. At that moment, the capsules of the ZGAs may be extensively stretched. In forward flexed positions and sitting postures the posterior spinal joints are relatively unloaded in compression but they carry more than 50 % of the anterior shear load. The ZGAs are loaded most heavily in torsion under compression.
When the intervertebral discs start degenerating and disc space narrowing ensues, the forces (N) and stresses (N/m²) on the ZGA joints may increase up to 70 % depending on the spinal posture. An average of 36 % increase in the ZGA pressure has been measured for a 1-mm loss in disc height and an average of 61 % for a 4-mm disc narrowing.
Fig. 11a. (Left) and 11b.(Right): Typical and routine radiological views of internal disc degeneration with subsequent structural destruction of the ZGA joints. This patient never experienced low back pain
As there is no cartilage at the tip of the ZGA joints, these structures are not supposed to resist compressive forces. As narrowing of the IVD progressively occurs, the ZGAs undergo subluxation until the tips of the inferior facets impinge on the vertebral laminae. This evolution increases the contact areas as well as the load transmission between the ZGAs (especially during extension movements). Increased compressive forces cause increased peak pressures and initiate thinning of the articular cartilage in the ZGAs. Both processes of subluxation and cartilage thinning cause capsular laxity allowing more abnormal motions and hypermobility in the motion segment which already was initiated by IVD degeneration. In the more advanced stages of IVD degeneration (and more disc space narrowing), the neural arch starts stress shielding the posterior annulus (in extension) allowing even more compressive load to be transmitted through the ZGAs and the neutral arch (and the anterior annulus). In these stages of IVD degeneration, more degeneration of the cartilage at the ZGAs will occur and give rise to bony hypertrophy and osteophytes, stabilising the segmental hypermobility and altering other spinal motion segments. The final immobilisation of the deformed ZGAs and motion segments may be associated with the development of lumbar spinal stenosis compressing the cauda equina, lateral canals and the nerve roots (Fig.11a and 11b).
Fig. 11b. R. (A90/149): Paramedian sagittal section through two adjacent degenerated intervertebral discs. Both upper L1-L2 and L2-3 IVDS are grossly disrupted. The ZGA joint is grossly degenerated: hypertrophic, reactively remodeled assuming a transverse orientation and no longer the ball-and-socket configuration
12. ZGA joints guide but limit segmental motion
The ZGAs maintain alignment, allow but limit segmental mobility between two adjacent lumbar vertebrae when exposed to flexion-extension, lateral bending and/or rotational forces. However, once the aging and degenerative processes start with ensuing narrowing of the disc space, the intervertebral disc (IVD) always will lead to alterations in the biomechanical loading patterns of the zygapophysial joints.
The amplitude and direction of the movements at each spinal segment (= 2 vertebrae, the IVD and the 2 ZGA joints) are determined by the 3-D orientation of the planes of the ZGAs. These posterior articulations limit lateral bending but are mainly designed for resisting torsion movements and forces. Although the twisting movements in the lumbar spine are coupled with various combinations of lateral bending, flexion, and extension, the normal motion segment is stiff when pure axial rotation is attempted (McFadden; Farfan). The ZGAs block the lumbar axial rotation which has been calculated to be extremely limited to allow only 2° to 3° in each direction (to the left and to the right).The resistance to torsional stress is greater in the more sagittally oriented L1-L2, L2-L3, and L3-4 ZGAs. This explains why the corresponding IVDs are better protected from severe rotational injuries. Indeed, degenerative annular tears are much more frequent in the IVDs at the lower L4-5 and L5-S1 segments where the ZGAs are more frontally oriented.
13. ZGA joints: traumatic intra-articular lesions
When victims of road traffic accidents or falls need surgical procedures to stabilize their spinal fractures,capsular and cartilaginous lesions with exposure of the subchondral bone are frequent findings in the various facets of the ZGA joints. Accidents directly can tear the articular capsule and the ligamentum flavum and even damage the articulation causing cartilaginous fibrillation, synovitis and cysts. None of these intra-articular injuries can be visualized with the existing radiological methods. Then, pre-operative radiological absence of traumatic injuries to the vertebral bodies and/or to the intervertebral discs does not mean that the victims did not sustain lesions in the ZGA joints.
Post-mortem macroscopic and histologic analysis of ZGAs are presently the only available methods to diagnose various subtle lesions. This type of investigations is been performed in the Departments of Anatomy and Embryology (Prof JR Taylor), and Neuropathology (Prof BA Kakulas) at the University of Western Australia in Perth since 1958. Frequently encountered ‘subtle’ aberrations are: synovial plicae, intra-articular haemorrhages, splits in the articular cartilage, separations of the articular cartilage from the subchondral bone, subchondral bone infarctions, tears of the articular capsule, and fractures of the (mostly superior) articular processes (Fig. 13a, 13b, 13c, 13d). Tears of the ligamentum flavum in one or more joints are seen in +/- 77%.
Similar lesions are routine findings in all other synovial joints. All these abnormalities can be arthroscopically diagnosed and handled in the shoulder, elbow, hip, and knee. In the absence of degenerative lesions into the lumbar intervertebral discs, all the mentioned aberrations in the posterior joints may be the primary sources of continuing low back pain (Taylor).
Fig. 13a. (Left): intra-articular fracture at the tip of the IAP in an ZGA joint
Fig. 13b. (Right): intra-articular ZGA haemorrhages (M-A83-58)
Fig. 13c. (Left) and 13d. (Right): intra-articular ZGA joint fractures (Courtesy of professor JA Taylor, Perth, Australia)
14. ZGA joints: degenerative arthritis
It is evident that traumatic lesions of the capsules and the articular cartilage of the ZGA joints may consolidate. But when these lesions result in intraarticular irregularities, interfere with the normal gliding mechanism between the joint surfaces, and alter the normal biomechanical loading patterns, the lesioned ZGA is predisposed to early development of degenerative osteoarthritis. This evolution is similar to that in any other synovial joint in such situation.
In the non-traumatic situation, osteoarthritic changes in the ZGAs are secondary to the evolving degenerative processes inside the intervertebral disc. When the intervertebral disc starts losing its height, the cartilaginous surfaces of the inferior articular process (IAP) and the superior articular process (SAP) are subjected to increased pressures and stresses as well as abnormal motions which result in degradative structural and metabolic changes of the cartilage (Fig. 11a).
Unfortunately, not a lot can be done to halt the degenerative osteoarthritic processes. There exists no vaccination to prevent osteoarthritis. What is well known, is that the quantity, the quality and the osmolarity of the remaining synovial tissues and the articular cartilage can be maintained by daily appropriate gentle active and passive mobility exercises.
It needs to be reminded that osteoarthritis does not equal pain. A huge amount of middle-aged adults worldwide have typical radiological signs of OA in their hips, knees, shoulders, elbows, spines and other joints, but only few experience discomfort, disabling pain or functional limits. On the other hand, people with radiological ‘normal ’ joints may have pain.
Likewise, ZGAs with a radiological image of degeneration and/or osteoarthritis can be totally asymptomatic while ZGAs with none or minimal structural derangement may be the source of pain.
15. Can zygapophysial joint(s) cause low back pain?
Yes. The role of the ZGA joints in generating pain was first proposed in 1911 (Goldthwait). But the modern diagnostic methods still do not allow to indicate that the ZGA is the sole responsible factor for developing (chronic) low back pain. Finally ‘diagnosing’ a lumbar zygapophysial joint as the main reason for low back pain is based on ‘trial and error’ thinking and handling. However, it is totally acceptable that a ZGA may account for part of a spinal problem. Indeed, the prevalence of the posterior spinal joint as an additional part of pain symptoms in the lumbar spine has been suggested to vary between 15 % and 40 %.
Some symptoms in some low back pain sufferers can be caused by accidents and/or evolving osteoarthritis of the ZGA joint.
Deformation or stretching or distension of the joint capsule and irritation of synovium in normal, in degenerating and in degenerated ZGAs may be the mechanical sources of pain as they stimulate the available pain receptors. But in the degenerated ZGA, it has been clearly shown that only 30 % of the capsules are sensitive to mechanical stimulation (Kuslich). Because the degenerated ZGAs present irregular or absent cartilaginous lining, pain may be explained as well by irritation of the subchondral bone. Bone tissue contains nerve endings sensitive to substance P, an essential molecule involved in the transmission and sensation of pain.
Although all the above have been scientifically proven, typical and diagnostic clinical and radiological signs and symptoms do not exist to delineate an unique articular disorder of the spine called ‘lumbar facet syndrome’.
16. Can ‘facet joint syndrome’ be defined?
In 1933 the controversial term of ‘facet syndrome’ was brought forward. But as this syndrome was not irrevocably defined, since then a lot has been published regarding this ‘syndrome’. Although there is no doubt at all that low back pain may originate primarily from a ZGA joint complex, it has been estimated that on its own the ZGA is responsible for only 2 % to 7 % of low back pain symptoms.
Even this estimation and based on my own exclusive spinal formation, my spinal surgical experience, and intense review of the spinal literature, I still have no clue what really means a ‘facet syndrome’ and how to diagnose it correctly.
In my opinion, and except for patients who suffer ‘inexplicable’ low back pain problems and presenting totally ‘normal’ discovertebral radiological investigations as a consequence of trauma, it is not at all evident to conclude that a ZGA joint complex may be the solely responsible structure. The patient’s history, physical examination, and imaging studies are unreliable to conclude to the certainty that the ZGA is the sole culprit.
Both the intervertebral discs (IVDs) and the ZGAs share load during all weight bearing situations. However, the ZGAs are loaded most heavily in torsion under compression. Consequently and from clinical perspective, low back pain should be intensified by motions that are known to load the ZGAs primarily. Then, a history of intermittent bouts of low back pain brought on by movements of combined lateral bending, rotating and arching backward with or without causing referred (= non-topographical, non-radicular) leg pain and subsequently lessened by fluently bending forward, is suggestive for a ‘pathological’ ZGA joint. At least when the IVDs are intact and well hydrated. Degenerative disc lesions can excite exactly the same intermittent bouts of low back pain in the chronic intermittent or in the chronic undulating LBP situations.
The presence of a well localized and mostly unilateral tender spot - and in the absence of abnormal neurologic motor findings - further indicates a potential ZGA problem.
Because the ZGA is a synovial joint, rising in the morning may not be easy. Daily appropriate gentle active and passive physical activities ease symptoms in most painful synovial joints as they maintain the quantity, the quality, and the osmolarity of the remaining synovial tissues and the articular cartilage. Then, LBP aggravated by rest in any posture, including recumbency (e.g. pain at night), and subsequently relieved by repeated or continuous gentle movement (Eisenstein) may further suggest the involvement of a ZGA joint.
But the clinical diagnostic problem remains. LBP due to internal degenerative disc disruptions, endplate fissures and annular ruptures are associated with morning stiffness, pain at night, and the urge to move around the settle the pains (even at night).
On top of it - and especially for those who only rely on radiological ‘images’ for their diagnoses - all existing imaging studies have been shown to be invalid and unreliable as diagnosing methods to conclude to a so-called isolated ‘facet’ syndrome. There exists no correlation between the aforementioned symptoms and signs and osteoarthritic features seen on plain XR, CAT, MRI, arthrography etc …. All the aging and degenerative changes are universally present in all synovial joints of the human body in …. asymptomatic individuals!
The ZGA joints are part of low back pain but rarely as primary reason. Evaluations of post-mortem lumbar spines confirm the findings by CAT and MRI findings: ‘facets degenerate after disc degeneration’.
17. Lumbar ZGA joints: substance P pain sensitive receptors
The dorsal rami of the outgoing lumbar nerve roots give rise to medial branch nerves which provide a rich innervation for the lumbar zygapophysial joints. The capsule of each ZGA may receive medial branches from up to three spinal nerve roots. For example, the L3-L4 ZGA may receive rich innervation provided by the medial branches originating from the L2, L3 and L4 spinal nerve roots (Bogduk).
Although less consistent than in the cervical ZGA joints, the fibrous capsules as well as the synovial lining of the lumbar ZGAs are well innervated. They contain a variety of free and encapsulated mechanoreceptive and afferent nociceptive nerve endings which both are substance P immunofluorescent.
As the ZGAs are load bearing structures, excessive physiological loads but especially abnormal loads due to intervertebral disc degeneration, may induce pain by stimulating the pain sensory nerves. Mechanical irritation of intraarticular ZGA synovial inclusions and/or capsular structures during abnormal spinal positions, compression, pinching, tension, stretching, etc … are sensed by the mechanoreceptors. This normally results in a reflex activity of the paraspinal muscles to regulate function, position, and balance of the lumbar spine (Indahl).
18. ZGA joints: intraarticular versus pericapsular needling
All the needling procedures, extraarticular, intraarticular or combined techniques, remain a field of challenge and experimentation. None is superior to the other. None is definitely diagnostic to indicate that the ZGA joint is the only reason inducing low back pain. Some low back pain patients will have ‘spectacular’ pain relieving results. But in one and the same patient, sometimes intraarticular injections will prove to be superior to pericapsular injections, sometimes it will be the opposite. There is simply no rationale for predicting an outcome of an injection in or around a ZGA joint.
19. ZGA joint arthrogram: simple? and diagnostic?
The major reason for performing an arthrography – under guiding radiographic control - is to localize the exact site for precisely inserting a needle and subsequently injecting a ‘therapeutic’ fluid into this small joint.
Only a few drops of dye are necessary (one drop ~ 0,05 cc) to visualise the ‘inside’ of the ZGA which volume is no greater than 1,5 cc. The initial contrast injection may reveal an inflammation of the synovium (synovitis), an occasional synovial cyst, an intraarticular fracture, or even confirm a spondylolysis.
However, the interpretation of a radiographic contrast-filled ZGA has nearly no value compared to similar arthrograms of large joints (hip, knee, shoulder, etc …). The joint is simply too small to visualise the lesions which are frequently encountered during macro- and microscopic investigations of these joints at autopsy.
Inadvertently or unknowingly injecting a larger volume of dye (1,5 to 2 cc) stretches the capsule joint (Fig. 4c) and may irritate the substance P containing mechanoreceptors and nociceptors. The (re)produced low back pain may then be so intense that further ‘therapeutic’ intraarticular or pericapsular injection needs to be abandoned.
20. Intraarticular ZGA injections: diagnostic? therapeutic?
It is well-known that intraarticular ZGA joint injections in asymptomatic volunteers may cause severe but short-term pain in a specific area of the low back. Indeed, the nociceptive nerve endings in the intracapsular synovial structures can react accordingly. In these cases and when referred pain would arise in the buttocks, posterior thigh and below the knee, the temporarily discomfort can even be associated with positive neuromeningeal tension signs which disappear rapidly when the capsule no longer is stretched.
More than 100 years following the suggestion that a lumbar ZGA joint may induce low back pain (1911), it remains frustrating that a diagnostic or therapeutic ‘block’ does not unequivocally indicates that a lumbar zygapophysial joint may be the pain culprit.
Most percutaneous needling procedures of ZGAs were initiated in the late 1970s. Different injections of water (normal, isotonic, or hypertonic saline) and/or an anaesthetic (bupivacaine / lignocaine) and/or corticosteroids (hydrocortisone / methylprednisolone acetate) were and are still tried. Whatever the combination, none has been proven to be better than the other. In other words, corticosteroid injections are no better than saline (water) injections. There exists no rational explanation for it but only indicates that the ZGA joint rarely is the single or primary cause of low back pain and/or referred leg pain.
All types of ZGA joint injections can provoke low back pain and temporary referred leg pain. They can evoke short-term symptomatic relief of low back pain or have no effect at all. Only 68 % of chronic low back pain sufferers report rapid initial but temporary symptomatic relief. Complete long-term relief (more than 6 months) is present in only 6 % to 20 %.
Single ZGA joint ‘blocks’ are reported to have a false-positive rate of 38 % (Schwarzer). ZGA ‘blocks’ have even been associated with a placebo response rate of 32 %. Note that there is nothing wrong with a placebo! Patients who possess the specific genetic variation of the COMT-enzyme (= catecholamine-O-methyltransferase-gene) on their DNA, produce more serotonin and dopamine in their prefrontal cortex, hormones responsible for a satisfying response (Finniss; Hall).
21. How many and which ZGA joints need to be ‘blocked’?
Deciding which ZGA joints should be needled is rather arbitrarily. Because there are no objective grounds to judge which ZGA joint(s) is/are the culprit, the decision can only be made from the patient’s pain distribution and the radiological ‘pictures’.
From an anatomical point of view, at least two (but better three) joints should be injected if only one is ‘found’ to be the culprit, three to four if two ZGAs are considered responsible (Fig. 21), …. Trying to find out which ZGA then finally is the most probable cause of pain remains wishful thinking and handling or as the Germans define:‘fingerspitzengefühl’.
And of course, repetitive anaesthetic blocks at different levels and on separate occasions may eliminate the ‘cheating’ joints. Once the culprit found, the infiltrating technique may be repeated over and over again.
Fig. 21. Totally inaccurate investigation as minimum two levels need to be explored The cornerstone for all healing processes is the production of scar tissue. The formation of collagens depends for 80 % on piezoelectric effects (Fukada; Minary-Jolandan). Then, healing effects of andullation are explained by the fact that vibrations penetrate into the body, transform the collagen fibrils, and as such induce the required piezoelectric effects for the fibroblasts to fulfil their synthetic activities.
22. Intraarticular ZGA injections as epidural blocks?
To avoid extravasation, the total injected volume of a diagnostic or therapeutic fluid needs to be as small as possible: maximum 1,5 cc. The volume of the small ZGA joint is estimated at only 1,5 cc.
When excess fluid is injected, greater manual pressure is needed. Then, leakages occur through the normal anatomical openings in the superior and/or the inferior parts of the ZGA joints (Fig. 4b). Leakages may occur as well through unexpected ruptures in the capsule joint caused by trauma and which were never visible during the (repeated) radiographic investigations.
If the volume of the diagnostic or therapeutic fluid to be injected is not respected, surplus of anaesthetic and/or a corticosteroid will leak into the epidural space ending up in a combined ZGA joint and epidural block.
23. Conclusion regarding intraarticular ZGA joint ‘blocks’
It is evident that the diagnosis of a pathologic ZGA joint responsible for low back pain (LBP) is considered when relief of pain is achieved. However, it has long been known that an injection into a ZGA is of little durable value in the treatment of patients with LBP (Carette; Jackson). Any disappearance or decrease of pain is coincidental and eventually transient.
Intraarticular ‘blocking’ of a ZGA remains an aspecific, unreliable and unpredictable modality for potentially diagnosing and/or treating low back pain even if it results in temporarily relieve of pain. The only conclusion that can be made from a ‘successful’ ZGA infiltration is that part of the patient’s low back pain and referred leg pain is attributable to a lumbar ZGA joint. Nothing more. Nothing less.
Pathologic changes in the lumbar spine are rarely isolated to a single ZGA. From biomechanical and functional point of view, this observation is totally normal and logic to explain. In response to the processes of intervertebral disc degeneration, internal nuclear disruption and consequent loss of disc height, the ZGAs will undergo higher mechanical strains during spinal loading. It ultimately affects both the structure and function of the disco-ZGA joint complex bridging two adjacent vertebral bodies. Post-mortem and radiological studies indicate that, except in traumatic cases, the intervertebral disc nearly always degenerates before ZGA joints. The anatomopathological findings during analysis of the different lumbar disco-ZGA joint complexes (including the thoracolumbar and the lumbosacral levels) in over twenty-three thousand post-mortem cases (23,000!) in the Department of Neuropathology in Perth, Western Australia (1958 till 1991), concluded that ZGA joint involvement followed degenerative IVD pathology in 98 % of all examined specimens.
The day innovative scanning devices will be able to monitor the human cellular and molecular damage (Chung) at spinal level, it will become possible to associate directly the post injection period of relief of low back pain with the nature and the ‘degree’ of intervertebral joint and ZGA joint degeneration.
24. Extraarticular nerve block or thermocoagulation
Those who consider an intraarticular ZGA joint procedure a controversial and non-reliable diagnostic and/or therapeutic procedure concentrate on an extraarticular needling procedure of the posterior spinal joints (for anatomic reasons at least two!).
The dorsal rami of identical spinal nerve roots give rise to medial branches whose nerve endings (mechanoreceptors and nociceptors) terminate inside and on the outside capsular structure of the ZGAs.
Extraarticular capsular needle probing techniques are applied frequently. Saline, anaesthetics and/or corticosteroids are injected locally to these medial branches or directly around the capsules of a suspected ZGA joint (Fig. 24).
So-called lumbar ZGA joint denervation by ‘burning’ the nerves with radiofrequency waves through a needle (= percutaneous rhizotomy or rhizolysis) was introduced in the 1970’s (Rees; Shealy). Thermocoagulation of these nerves has no value as the nerves will ‘regenerate’.
However, it remains totally unpredictable if those extraarticular needling procedures will achieve some short-term or no-term pain relief. Conclusions can never been extrapolated.
Fig. 24. Example of an extraarticular lumbar medial nerve branch block. Because the nerve branch passes at the level between the transverse process and the superior articular process (SAP), the tip of the needle is positioned in this zone to inject local anesthetic, sterile water or a corticosteroid. Skilled and sensitive fingers do inject the ‘therapeutic’ fluids at different points of the capsule without penetrating the ZGA joint
25. Additional conservative pain relieving method
Biophysical methods using energy (e.g. warmth, electric currents, UV light, IR radiation, ultrasonic sound, laser beams, magnetic fields, etc ...) are physiotherapeutic tools to suppress low back pain complaints. Andullation induces energy by applying low frequency vibrations in combination with infrared light. The pain inducing effect of andullation is explained by the theory of Melzack and Wall. The vibrating sensory stimuli applied to the skin are filtered by the T cells in the spinal cord (‘gate control’) before being forwarded to the brain where pain relieving effects result. Because the mechanically generated vibrations are stochastically modulated, andullation can be employed for long times activating the liberation of pain relieving endorphins.
The cornerstone for all healing processes is the production of scar tissue. The formation of collagens depends for 80 % on piezoelectric effects (Fukada; Minary-Jolandan). Then, healing effects of andullation are explained by the fact that vibrations penetrate into the body, transform the collagen fibrils, and as such induce the required piezoelectric effects for the fibroblasts to fulfil their synthetic activities.
26. Literature Encyclopaedia
Abumi K, Panjabi MM, Kramer KM, Duranceau J, Oxland T, Crisco JJ
Biomechanical evaluation of lumbar spinal stability after graded facetectomies
Spine, 1990, 15:1142
Adams MA, Hutton WC
The effect of posture on the role of the apophyseal joints in resisting intervertebral compressive forces
J Bone Joint Surg, 1980, 62B:358
Adams MA, Hutton WC
The mechanical function of the lumbar apophyseal joints
Spine, 1983, 8:327
Adams MA, Hutton WC
The relevance of torsion to the mechanical derangement of the lumbar spine
Spine, 1981, 6:241
Adams MA, May S, Freeman BJ, Morrison HP, Dolan P
Effects of backward bending on lumbar intervertebral discs. Relevance to physical therapy treatments for low back pain
Spine, 2000, 25:431
Ashton IK, Ashton BA, Gibson SJ, Polak JM, Jaffray DC, Eisenstein SM
Morphological basis for back pain. The demonstration of nerve fibers and neuropeptides in the lumbar facet
joint capsule but not in ligamentum flavum
J Orthop Res, 1992, 10:72
Avramov AI, Cavanaugh JM, Ozaktay CA, Getchell TV, King AI
The effects of controlled mechanical loading on group-II, III, and IV afferent units from the lumbar facet joint and surrounding tissue. An in vitro study
J Bone Joint Surg, 1992, 74A:1464
The articular facets in relation to low-back pain and sciatic radiation
J Bone Joint Surg, 1941, 23A:481
Baumgarten M, Bloebaum RD, Ross SD, Campbell P, Sarmiento A
Normal human synovial fluid. Osmolarity and exercise-induced changes
J Bone Joint Surg, 1985, 67A:1336
Beaman DN, Graziano GP, Glover RA, Wojtys EM, Chang V
Substance P innervation of lumbar spine facet joints
Spine, 1993, 18:1044
Berven S, Tay BB, Colman W, Hu SS
The lumbar zygapophyseal (facet) joints. A role in the pathogenesis of spinal pain syndromes and
Semin Neurol, 2002, 22:187
Boden SD, Riew KD, Yamaguchi K, Brach TP, Schellinger D, Wiesel SW
Orientation of the lumbar facet joints. Association with degenerative disc disease
J Bone Joint Surg, 1996, 78A:403
The innervation of the lumbar spine
Spine, 1983, 8:286
Bogduk N, Engel R
The menisci of the lumbar zygapophyseal joints. A review of their anatomy and clinical significance
Spine, 1984, 9:454
Bogduk N, Long DM
Percutaneous lumbar medial branch neurotomy. A modification of facet denervation
Spine, 1980, 5:193
Bogduk N, Long DM
The anatomy of the so-called "articular nerves" and their relationship to facet denervation in the treatment of
J Neurosurg, 1979, 51:172
Bogduk N, Twomey LT
Clinical anatomy of the lumbar spine. 2nd ed
Churchill Livingstone, Melbourne, 1991
Bogduk N, Wilson AS, Tynan W
The human lumbar dorsal rami
J Anat, 1982, 134:383
Bough B, Thakore J, Davies M, Dowling F
Degeneration of the lumbar facets joints. Arthrography and pathology
J Bone Joint Surg, 1990, 72B:275
Deformities of the lumbosacral region of the spine
Brit J Surg, 1929, 16:562
Butler D, Trafimow JH, Andersson GB, McNeill TW, Huckman MS
Discs degenerate before facets
Spine, 1990, 15:111
Carette S, Marcoux S, Truchon R, Grondin C, Gagnon J, Allard Y, Latulippe M
A controlled trial of corticosteroid injections into facet joints for chronic low back pain
N Engl J Med, 1991, 325:1002
Lumbar facet joint injection in low back pain and sciatica. Description of technique
Radiology, 1980, 137:661
Carrera GF, Williams AL
Current concepts in evaluation of the lumbar facet joints
Crit Rev Diagn Imaging, 1984, 21:85
Carrera GF, Williams AL, Haughton VM
Computed tomography in sciatica
Radiology, 1980, 137:433
Carter DR, Orr TE, Fyhrie DP, Schurman DJ
Influences of mechanical stress on prenatal and postnatal skeletal development
Clin Orthop Relat Res, 1987, 219:237
Carter DR, Wong M
Mechanical stresses and endochondral ossification in the chondroepiphysis
J Orthop Res, 1988, 6:148
Cassidy JD, Loback D, Yong-Hing K, Tchang S
Lumbar facet joint asymmetry. Intervertebral dis herniation
Spine, 1992, 17:570
Cavanaugh JM, El-Bohy A, Hardy WN, Getchell TV, Getchell ML, King AI
Sensory innervation of soft tissues of the lumbar spine in the rat
J Orthop Res, 1989, 7:378
Cavanaugh JM, Ozaktay AC, Yamashita HT, King AI
Lumbar facet pain. Biomechanics, neuroanatomy and neurophysiology
J Biomech, 1996, 29:1117
Chung K, Wallace J, Kim SY, Kalyanasundaram S, Andalman AS, Davidson TJ, Mirzabekov JJ, Zalocusky KA, Mattis J, Denisin AK, Pak S, Bernstein H, Ramakrishnan C, Grosenick L, Gradinaru V, Deisseroth K
Structural and molecular interrogation of intact biological systems
Nature, 2013, 497:332
Cyron BM, Hutton WC
Articular tropism and stability of the lumbar spine
Spine, 1980, 5:168
Delmas A, Ndjaga-Mba M, Vannareth T
Le cartilage articulaire de L4-5 et de L5-S1
Comptes Rendus de l'association des anatomistes, 1970, 147:230
Destouet JM, Gilula LA, Murphy WA, Monsees B
Lumbar facet joint injection. Indication, technique, clinical correlation, and preliminary results
Radiology, 1982, 145 :321
Do DH, Taghavi CE, Fong W, Kong MH, Morishita Y, Wang JC
The relationship between degree of facet tropism and amount of dynamic disc bulge in lumbar spine of patients symptomatic for low back pain
Eur Spine J, 2011, 20:71
Dooris AP, Goel VK, Grosland NM, Gilbertson LG, Wilder DG
Load-sharing between anterior and posterior elements in a lumbar motion segment implanted with an artificial disc
Spine, 2001, 26:E122
Arthrography of the lumbar facet joints
Radiology, 1981, 140:23
Dreyfuss PH, Dreyer SJ, Herring SA
Lumbar zygapophysial (facet) joint injections
Spine, 1995, 20:2040
Dunlop RB, Adams MA, Hutton WC
Disc space narrowing and the lumbar facet joints
J Bone Joint Surg, 1984, 66B:706
Eisenstein SM, Parry CR
The lumbar facet arthrosis syndrome. Clinical presentation and articular surface changes
J Bone Joint Surg, 1987, 69B:3
El-Bohy A, Cavanaugh JM, Getchell ML, Bulas T, Getchell TV, King AI
Localization of substance P and neurofilament immunoreactive fibers in the lumbar facet joint capsule and
supraspinous ligament of the rabbit
Brain Res, 1988, 460:379
El-Bohy AA, King AI
Intervertebral disc and facet contact pressure in axial torsion
Adv Bioeng, 1986, 2:26
El-Bohy AA, Yang KH, King AI
Experimental verification of facet load transmission by direct measurement of facet lamina contact pressure
J Biomech, 1989, 22:931
Engel R, Bogduk N
The menisci of the lumbar zygapophysial joints
J Anat, 1982, 135:795
Esses SI, Moro JK
The value of facet joint blocks in patient selection for lumbar fusion
Spine, 1993, 18:185
Fairbank JC, Park WM, McCall IW, O’Brien JP
Apophyseal injection of local anesthetic as a diagnostic aid in primary low-back pain syndromes
Spine, 1981, 6:598
Mechanical disorders of the low back
Philadelphia, Lea & Febiger, 1973
Farfan HF, Cossette JW, Robertson GH, Wells RV, Kraus H
The effects of torsion on the lumbar intervertebral joints. The role of torsion in the production of disc
J Bone Joint Surg, 1970, 52A:468
Farfan HF, Huberdeau RM, Dubow HI
Lumbar intervertebral disc degeneration. The influence of geometric features on the pattern of disc
degeneration. A post mortem study
J Bone Joint Surg, 1972, 54A:492
Farfan HF, Sullivan JD
The relation of facet orientation to intervertebral disc failure
Can J Surg, 1967, 10:179
Finniss DG, Kaptchuk TJ, Miller F, Benedetti F
Biological, clinical, and ethical advances of placebo effects
The Lancet, 2010, 375:686
Frank C, Akeson WH, Woo SLY, Amiel D, Coutts RD
Physiology and therapeutic value of passive joint motion
Clin Orthop Relat Res, 1984, 185:113
Fukada E, Yasuda I
Piezoelectric Effects in Collagen
J Applied Physics, 1964, 3:117
Gamble JG, Edwards CC, Max SR
Enzymatic adaptation in ligaments during immobilization
Am J Sports Med, 1984, 12:221
Low back pain. With special reference to the articular facets, with presentation of an operative procedure
J Amer Med Assoc, 1933, 101:1773
Giles LG, Harvey AR
Immunohistochemical demonstration of nociceptors in the capsule and synovial folds of human
Br J Rheumatol, 1987, 26:362
Giles LG, Taylor JR
Human zygapophyseal joint capsule and synovial fold innervation
Br J Rheumatol, 1987, 26:93
Giles LG, Taylor JR
Intra-articular synovial protrusions in the lower lumbar apophyseal joints
Bull Hosp Jt Dis Orthop Inst, 1982, 42:248
Innervation of zygapophyseal joint synovial folds in low-back pain
The Lancet, 1987, 330:692
Giles LGF, Taylor JR
Innervation of lumbar zygapophyseal joint synovial joints
Acta Orthop Scand, 1987, 58:43
Giles LGF, Taylor JR, Cockson A
Human zygapophyseal joint synovial folds
Acta Anat, 1986, 126:110
The lumbo-sacral articulation. An explanation of many cases of "lumbago," "sciatica" and paraplegia
Boston Med Surg J, 1911, 164:365
Grigg A, Hoffman AH, Fogarty KE
Properties of Golgi-Mazzoni afferents in cat knee joint capsule, as revealed by mechanical studies of
isolated joint capsule
J Neurophysiol, 1982, 47:31
Mechanical factors influencing response of joint afferent neurons from cat knee
J Neurophysiol, 1975, 38:1473
Gurr KR, McAfee PC, Shih CM
Biomechanical analysis of posterior instrumentation systems after decompressive laminectomy. An unstable calf-spine model
J Bone Joint Surg, 1988, 70A:680
Anatomico-roentgenographic studies of the spine
Springfield, Charles C. Thomas, 1976
Hägg O, Wallner A
Facet joint asymmetry and protrusion of the intervertebral disc
Spine, 1990, 15:356
Haher TR, Felmy W, Baruch H, Devlin V, Welin D, O’Brien M, Ahmad J, Valenza J, Parish S
The contribution of the three columns of the spine to rotational stability. A biomechanical model
Spine, 1989, 14:663
Haher TR, O’Brien M, Dryer JW, Nucci R, Zipnick R, Leone DJ
The role of the lumbar facet joints in spinal stability. Identification of alternative paths of loading
Spine, 1994, 19:2667
Hakim NS, King AI
A three dimensional finite element dynamic response analysis of a vertebra with experimental verification
J Biomech, 1979, 12:277
Hall KT, Kaptchuk TJ
Genetic biomarkers of placebo response: what could it mean for future trial design?
Clinical Investigation, 2013, 3:311
Hall KT, Lembo AJ, Kirsch I, Ziogas DC, Douaiher J, Jensen KB, Conboy LA, Kelly JM, Kokkotou E, Kpatchuk TJ
Catechol-O-methyltransferase val158met polymorphism predicts placebo effect in irritable bowel syndrome
PloS One, 2012, 7, e48135
Horwitz T, Smith RM
An anatomical pathological and roentgenological study of the intervertebral joints of the lumbar spine and of
the sacroiliac joints
Am J Roentgenol, 1940, 43:173
Indahl A, Kaigle A, Reikeras O, Holm S
Electromyographic response of the porcine multifidus musculature after nerve stimulation
Spine, 1995, 20:2652
Indahl A, Kaigle AM, Reikeras O, Holm SH
Interaction between the porcine lumbar intervertebral disc, zygapophysial joints, and paraspinal muscles
Spine, 1997, 22:2834
Jackson HC II, Winkelmann RK, Bickel WH
Nerve endings in the human lumbar spinal column and related structures
J Bone Joint Surg, 1966, 48A:1272
The facet syndrome. Myth or reality?
Clin Orthop Relat Res, 1992, 279:11
Jackson RP, Jacobs RR, Montesano PX
1988 Volvo award in clinical sciences. Facet joint injection in low-back pain. A prospective statistical study
Spine, 1988, 13:966
Kato Y, Panjabi MM, Nibu K
Biomechanical study of lumbar spinal stability after osteoplastic laminectomy
J Spinal Disord, 1998, 11:146
Kénési C, Lesur E
Orientation of the articular processes at L4, L5, and S1. Possible role in pathology of the intervertebral disc.
Anat Clin, 1985, 7:43
Konttinen YT, Grönblad M, Korkala O, Tolvanen E, Polak JM
Immunohistochemical demonstration of subclasses of inflammatory cells and active, collagen-producing
fibroblasts in the synovial plicae of lumbar facet joints
Spine, 1990, 15:387
Kuslich SD, Ulstrom CL, Michael CJ
The tissue origin of low back pain and sciatica. A report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia
Orthop Clin North Am, 1991, 22:181
Lee KK, Teo EC, Qiu TX, Yang K
Effect of facetectomy on lumbar spinal stability under sagittal plane loadings
Spine, 2004, 29:1624
Die Arthritis deformans der kleinen Wirbelgelenke
Z Orthop, 1936, 65:42
Lewin T, Moffett B, Vidik A
The morphology of the lumbar synovial intervertebral joints
Acta Morphol Neerl Scand, 1962, 4:199
Liesi P, Grönblad M, Korkala O, Karaharju E, Rusanen M
Substance P. A neuropeptide involved in low back pain?
The Lancet, 1983, 1:1328
Lilius G, Harilainen A, Laasonen EM, Myllynen P
Chronic unilateral low-back pain. Predictors of outcome of facet joint injections
Spine, 1990, 15:780
Lilius G, Laasonen EM, Myllynen P, Harilainen A, Gronlund G
Lumbar facet joint syndrome. A randomised clinical trial
J Bone Joint Surg, 1989, 71B:681
Lin HS, Liu YK, Adams KH
Mechanical response of the lumbar intervertebral joint under physiological (complex) loading
J Bone Joint Surg, 1978, 60A:41
The facet joint and its role in spine pain. Management with facet joint injections
Spine, 1984, 9:746
Lora J, Long D
So-called facet denervation in the management of intractable back pain
Spine, 1976, 1:121
Lorenz M, Patwardhan A, Vanderby R Jr
Load-bearing characteristics of lumbar facets in normal and surgically altered spinal segments
Spine, 1983, 8:122
Lynch MC, Taylor JF
Facet joint injection for low back pain. A clinical study
J Bone Joint Surg, 1986, 68B:138
Maldague B, Mathurin P, Malghem J
Facet joint arthrography in lumbar spondylolysis
Radiology, 1981, 140:29
Marks RC, Houston T, Thulbourne T
Facet joint injection and facet nerve block. A randomised comparison in 86 patients with chronic low back pain
Pain, 1992, 49:325
McCall IW, Park WM, O’Brien JP
Induced pain referral from posterior lumbar elements in normal subjects
Spine, 1979, 4:441
McCormick CC, Taylor JR, Twomey LT
Facet joint arthrography in lumbar spondylolysis. Anatomic basis for spread of contrast medium
Radiology, 1989, 171:193
McFadden KD, Taylor JR
Axial rotation in the lumbar spine and gaping of the zygapophyseal joints
Spine, 1990, 15:295
Mechanoreceptor endings in human cervical facet joints
Spine, 1994, 19:495
McLain RF, Pickar JG
Mechanoreceptor endings in human thoracic and lumbar facet joints
Spine, 1998, 23:168
Mehta M, Sluijter ME
The treatment of chronic pain. A preliminary survey of the effect of radiofrequency denervation of the posterior vertebral joints
Anaesthesia, 1979, 34:768
Melzack R, Wall PD
Pain Mechanisms. A New Theory
Science, 1965, 150:171
Miller JAA, Haderspeck KA, Schultz AB
Posterior element loads in lumbar motion segments
Spine, 1983, 8:331
Minary-Jolandan M, Yu MF
Nanoscale characterization of isolated individual type I collagen fibrils. Polarization and piezoelectricity
Nanotechnology, 2009, 20: 085706
Mooney V, Robertson J
The facet syndrome
Clin Orthop Relat Res, 1976, 115:149
Moore RJ, Crotti TN, Osti OL, Fraser RD, Vernon-Roberts B
Osteoarthrosis of the facet joints resulting from anular rim lesions in sheep lumbar discs
Spine, 1999, 24:519
Moran R, O’Connell D, Walsh MG
The diagnostic value of facet joint injections
Spine, 1988, 13:1407
Computed tomography and fluoroscopy guided anesthesia and steroid injection in facet syndrome
Spine, 1988, 13:686
Nade S, Bell E, Wyke BD
The innervation of the lumbar spinal joint and its significance
J Bone Joint Surg, 1980, 62B:255
Natarajan RN, Andersson GB, Patwardhan AG, Andriacchi TP
Study on effect of graded facetectomy on change in lumbar motion segment torsional flexibility using
three-dimensional continuum contact representation for facet joints
J Biomech Eng, 1999, 121:215
Niemisto L, Kalso E, Malmivaara A, Seitsalo S, Hurri H
Radiofrequency denervation for neck and back pain
The Cochrane Database of Systematic Reviews 2003, Issue 1, Art n° CD004058
Noren R, Trafimow J, Andersson GB, Huckman MS
The role of facet joint tropism and facet angle in disc degeneration
Spine, 1991, 16:530
Oegema TR Jr, Bradford DS
The inter-relationship of facet joint osteoarthritis and degenerative disc disease
Br J Rheumatol, 1991, 30(Suppl 1):16
Ogsbury JS 3rd, Simon RH, Lehman RA
Fact “denervation” in the treatment of low back syndrome
Pain, 1977, 3:257
Diseases of the apophyseal (intervertebral) articulations
J Bone Joint Surg, 1938, 20A:285
Panjabi MM, Krag MH, Chung TQ
Effects of disc injury on mechanical behavior of the human spine
Spine, 1984, 9:707
Anatomy as related to function and pain
Orthop Clin North AM, 1983, 14:475
Pathria M, Sartoris DJ, Resnick D
Osteoarthritis of the facet joints. Accuracy of oblique radiographic assessment
Radiology, 1987, 164:227
Pedersen HE, Conrad FJ, Blunck, Gardner E
The anatomy of lumbosacral posterior rami and meningeal branches of spinal nerves (sinu-vertebral nerves)
with an experimental study of their functions
J Bone Joint Surg, 1956 38A:377
Peh WCG Image-guided facet joint injection
Biomed Imaging Interv, 2011, 7:e4
Pickar JG, McLain RF
Responses of mechanosensitive afferents to manipulation of the lumbar facet in the cat
Spine, 1995, 20:2379
Pintar FA, Cusick JF, Yoganadan N, Reinartz J, Mahesh M
The biomechanics of lumbar facetectomy under compression-flexion
Spine, 1992, 17:804
Prasad P, King AI, Ewing CL
The role of articular facets during +Gz acceleration
J Appl Mech, 1974, 41:321
New concepts in the pathogenesis of sciatic pain
The Lancet, 1927, 2:53
The functional morphology of the superior articular processes of the lumbar vertebrae
J Anat, 1985, 143:181
Rao RD, Wang M, Singhal P, McGrady LM, Rao S
Intradiscal pressure and kinematic behavior of lumbar spine after bilateral laminotomy and laminectomy
Spine J, 2002, 2:320
Raymond J, Dumas JM
Intraarticular facet block. Diagnostic test or therapeutic procedure?
Radiology, 1984, 151:333
Multiple bilateral sub-cutaneous rhizolysis in the treatment of the slipped disc syndrome
Ann Gen Pract, 1971, 16:126
Schellinger D, Wener L, Ragsdale BD, Patronas NJ
Facet joint disorders and their role in the production of back pain and sciatica
Radiographics, 1987, 7:923
Schendel MJ, Wood KB, Buttermann GR, Lewis JL, Ogilvie JW
Experimental measurement of ligament force, facet force, and segment motion in the human lumbar spine
J Biomech, 1993, 26:427
Schütz U, Cakir B, Dreinhöfer K, Richter M, Koepp H
Diagnostic value of lumbar facet joint injection. A prospective triple cross-over study
PLoS ONE, 2011, 6: e27991
Schwarzer AC, Aprill CN, Derby R, Fortin J, Kine G, Bogduk N
Clinical features of patients with pain stemming from the lumbar zygapophysial joints. Is the lumbar facet
syndrome a clinical entity?
Spine, 1994, 19:1132
Schwarzer AC, Aprill CN, Derby R, Fortin J, Kine G, Bogduk N
The false-positive rate of uncontrolled diagnostic blocks of the lumbar zygapophysial joints
Pain, 1994, 58:195
Schwarzer AC, Derby R, Aprill CN, Fortin J, Kine G, Bogduk N
Pain from the lumbar zygapophysial joints. A test of two models
J Spinal Disord, 1994, 7:331
Schwarzer AC, Wang SC, Bogduk N, mcNaught PJ, Laurent R
Prevalence and clinical features of lumbar zygapophysial joint pain. A study in an Australian population with chronic low back pain
Ann Rheum Dis, 1995, 54:100
Selby DK, Paris SV
Anatomy of facet joints and its correlation with low back pain
Contemp Orthop, 1981, 312:1097
Shah JS, Hampson WGJ, Jayson MIV
The distribution of surface strain in cadaveric lumbar spine
J Bone Joint Surg, 1978, 60B:246
Sharma M, Langrana NA, Rodriguez J
Role of ligaments and facets in lumbar spinal stability
Spine, 1995, 20:887
Facet denervation in the management of back and sciatic pain
Clin Orthop Relat Res, 1976, 115:157
Percutaneous radiofrequency denervation of spinal facets. Treatment for chronic back pain and sciatica
J Neurosurg, 1975, 43:448
Finite-element evaluation of contact loads on facets of an L2-L3 lumbar segment in complex loads
Shirazi-Adl A, Ahmed AM, Shrivastava SC
A finite element study of a lumbar motion segment subjected to pure sagittal plane moments
J Biomech, 1986, 19:331
Shirazi-Adl A, Ahmed AM, Shrivastava SC
Mechanical response of a lumbar motion segment in axial torque alone and combined with compression
Spine, 1986, 11:914
Shirazi-Adl A, Drouin G
Load-bearing role of facets in a lumbar segment under sagittal plane loadings
J Biomech, 1987, 20:601
Stilwell DL Jr
The nerve supply of the vertebral column and its associated structures in the monkey
Anat Rec, 1956, 125:139
Taylor JR, Twomey LT
Age changes in lumbar zygapophyseal joints. Observations on structure and function
Spine, 1986, 11:739
Taylor JR, Twomey LT
Age changes in the subchondral bone of human lumbar apophyseal joints
J Anat, 1985, 143:233
Taylor JR, Twomey LT, Corker M
Bone and soft tissue injuries in post-mortem lumbar spines
Paraplegia, 1990, 28:119
Age changes in the human lumbar vertebral column
Thesis. Perth, Western Australia
The University of Western Australia, 1981
Twomey LT, Taylor JR
Age changes in the lumbar articular triad
Aust J Physiother, 1985, 31:106
Twomey LT, Taylor JR, Taylor MM
Unsuspected damage to lumbar zygapophyseal (facet) joins after motor-vehicle accidents
Med J Aust, 1989, 151:210
Vanharanta H, Floyd T, Ohnmeiss DD, Hochschuler SH, Guyer RD
The relationship of facet tropism to degenerative disc disease
Spine, 1993, 18:1000
van Kampen GP, Veldhuijzen JP, Kuijer R, van de Stadt RJ, Schipper CA
Cartilage response to mechanical force in high-density chondrocyte cultures
Arthritis Rheum, 1985, 28:419
Van Schaik JP, Verbiest H, Van Schaik FD
The orientation of laminae and facet joints in the lower lumbar spine
Spine, 1985, 10:59
Wang S, Xia Q, Passias P, Li W, Wood K, Li G
How does lumbar degenerative disc disease affect the disc deformation at the cephalic levels in vivo?
Spine, 2011, 36:E574
White AA III, Panjabi MM (eds)
Clinical biomechanics of the spine (2nd ed)
JB Lippincott Company, Philadelphia, 1990
Wiesel SW, Tsourmas N, Feffer HL, Citrin CM, Patronas N
A study of computer-assisted tomography. I. The incidence of positive CAT scans in an asymptomatic group
Spine, 1984, 9:549
Wilson DC, Niosi CA, Zhu QA, Oxland TR, Wilson DR
Accuracy and repeatability of a new method for measuring facet loads in the lumbar spine
J Biomech 2006, 39:348
The neurology of joints. A review of general principles
Clin Rheum Dis, 1981, 7:223
Yamashita T, Cavanaugh JM, el-Bohy AA, Getchell TV, King AI
Mechanosensitive afferent units in the lumbar facet joint
J Bone Joint Surg, 1990, 72A:865
Yamashita T, Cavanaugh JM, Ozaktay AC, Avramov AI, Getchell TV, King AI
Effect of substance P on mechanosensitive units of tissues around and in the lumbar facet joint
J Orthop Res, 1993, 11:205
Yamashita T, Minaki Y, Ozaktay AC, Cavanaugh JM, King AI
A morphological study of the fibrous capsule of the human lumbar facet joint
Spine, 1996, 21:538
Yang KH, King AI
Mechanism of facet load transmission as a hypothesis for low back pain
Spine, 1984, 9:557
Zander T, Rohlmann A, Klöckner C, Bergmann G
Influence of graded facetectomy and laminectomy on spinal biomechanics
Eur Spine J, 2003, 12:427