Lumbosacral Facet Syndrome

The first discussion of the Z-joint as a source of LBP was by Goldwaith in 1911.[8]  In 1927, Putti illustrated osteoarthritic changes of Z-joints in 75 cadavers of persons older than 40 years.[9]  In 1933, Ghormley coined the term facet syndrome, suggesting that hypertrophic changes secondary to osteoarthritis of the zygapophyseal processes led to lumbar nerve root entrapment, which caused LBP.[10]  In the 1950s, Harris and Mcnab[11]  and McRae[12]  determined that the etiology of Z-joint degeneration was secondary to intervertebral disc degeneration.

Hirsch et al were later able to reproduce LBP with injections of hypertonic saline solution into the Z-joints, thus affirming the role of the Z-joints as a source of LBP.[13]  Mooney and Robertson also performed provocative hypertonic saline Z-joint injections and recorded pain referral maps with radiation mainly to the buttocks and posterior thigh.[14]

Frequency

United States

LBP is the most common musculoskeletal disorder of industrialized society and the most common cause of disability in persons younger than 45 years. Given that 90% of adults experience LBP sometime in their lives, the fact that it is the second leading cause for visits to primary care physicians and the most frequent reason for visits to orthopedic surgeons or neurosurgeons is not surprising. As the primary cause of work-related injuries, LBP is the most costly of all medical diagnoses when time off from work, long-term disability, and medical and legal expenses are taken into account.[73]

The lumbosacral Z-joint is reported to be the source of pain in 15-40% of patients with chronic LBP. Ray believed that Z-joint–mediated pain is the etiology for most cases of mechanical LBP,[15] whereas other authors have argued that it may contribute to nearly 80% of cases. Thus, the diagnosis and treatment of this entity may help alleviate LBP in a significant number of patients.

International

International data on lumbosacral facet syndrome have not been clearly established.

The spine is composed of a series of functional units. Each unit consists of an anterior segment, which is made up of 2 adjacent vertebral bodies and the intervertebral disc between them, and the posterior segment, which consists of the laminae and their processes. One joint is formed between the 2 vertebral bodies, whereas the other 2 joints, known as the Z-joints, are formed by the articulation of the superior articular processes of one vertebra with the inferior articular processes of the vertebra above. Thus, the Z-joints are part of an interdependent functional spinal unit consisting of the disc-vertebral body joint and the 2 Z-joints, with the Z-joints paired along the entire posterolateral vertebral column.

In the lumbar spine, the superior articular processes face anterolaterally, whereas the inferior articular processes face posteromedially. The superior articular process has a concave orientation in order to accommodate the more convex orientation of the inferior articular process. The upper lumbar Z-joints are oriented in a sagittal plane, whereas the lower lumbar Z-joints approach a more frontal orientation. Thus, as the lumbosacral Z-joints maintain a progressive coronal orientation, greatest at the S1 level, they are functionally able to resist rotation in the upper lumbar region as well as resist forward displacement in the lower lumbosacral region.

The Z-joint is considered a motion-restricting joint, able to resist stress and withstand both axial and shearing forces. In back extension, the Z-joints, along with the intervertebral discs, absorb a compressive load. In addition, the transmission of the Z-joint load occurs through contact of the tip of the inferior articular process with the pars of the vertebra below. The overloaded Z-joint then causes posterior rotation of the inferior articular process, resulting in stretching of the joint capsule.

If one considers the disc and each of the adjacent Z-joints as an interdependent functional spinal unit, degenerative changes within this 3-joint complex can influence each of the segments. Thus, degeneration of the discs can lead to loss of disc height, resulting in a relative increase in Z-joint load that is found in compression and extension maneuvers. One theory is that these excessive Z-joint loads cause the inferior articular process to pivot about the pars and stretch the joint capsule, in addition to causing rostrocaudal subluxation (ie, Z-joint malalignment). Thus, some authors postulate that Z-joints undergo osteoarthritic changes in response to disc degeneration secondary to changes in loading. 80% of the loading weight is carried through the vertebral bodies and intervertebral discs and 20% by the Z-joints. However, thinning of the intervertebral discs from wear and tear causes more weight bearing through the Z-joints. This in turn results in arthropathy and slight angulation deformity, or a more horizontal orientation, which allows for degenerative spondylolisthesis to occur. Most commonly, this occurs at L4-5 and to a lesser degree at the superior levels.

The Z-joint is a common pain generator in the lower back. The 2 common mechanisms for this generation of pain are either (1) direct, from an arthritic process within the joint itself, or (2) indirect, in which overgrowth of the joint (eg, Z-joint hypertrophy or a synovial cyst) impinges on nearby structures.

The Z-joints are diarthrodial joints with a synovial lining, the surfaces of which are covered with hyaline cartilage, which is susceptible to arthritic changes and arthropathies. Repetitive stress and osteoarthritic changes to the Z-joint can lead to zygapophyseal hypertrophy. Like any synovial joint, degeneration, inflammation, and injury can lead to pain with joint motion, causing restriction of motion secondary to pain and, thus, deconditioning. In addition, Z-joint arthrosis, particularly trophic changes of the superior articular process, can progress to narrowing of the neural foramen. In addition, as is the case for any synovial joint, the synovial membrane can form an outpouching and, thus, a cyst. Z-joint cysts are most commonly seen at the L4-L5 level (65%), but they are also seen at the L5-S1 (31%) and L3-L4 (4%) levels. These synovial cysts can be clinically significant, particularly if they impinge on nearby structures (eg, the existing nerve root).

The neural foramen is bordered by the superior articular process, pars interarticularis, and posterior portion of the vertebral body. Z-joint hypertrophy or a synovial cyst can contribute to lateral and central lumbar stenosis, which can lead to impingement on the exiting nerve root. Thus, Z-joint pain can occasionally produce a pain referral pattern that is indistinguishable from disc herniation.

To understand the pattern of pain generation from the Z-joint, knowledge of the innervation pattern is essential. This pattern is frequently misunderstood even by experienced practitioners. Each Z-joint is innervated by branches of the dorsal ramus, termed the medial branch. The medial branch is 1 of 3 branches of the dorsal ramus, with the other 2 being the lateral branch (which does not exist for the L5 dorsal ramus) and the intermediate branch. The lateral branch innervates the iliocostalis muscle, and the intermediate branch innervates the longissimus muscle. The medial branch innervates many structures, including the Z-joint, but it also innervates the multifidus, interspinales, and intertransversarii mediales muscles, the interspinous ligament, and, possibly, the ligamentum flavum (see image below).

After the medial branch splits off from the dorsal ramus, it courses caudally around the base of the superior articular process of the level below toward that level’s Z-joint (eg, the L2 medial branch wraps around the L3 superior articular process to approach the L2-L3 Z-joint). The medial branch then continues in a groove between the superior articular process and transverse process (or, in the case of the L5 medial branch, between the superior articular process of S1 and the sacral ala of S1, which is the homologous structure to the transverse processes of the lumbar vertebrae). As it makes this course, the medial branch is held in place by a ligament joining the superior articular process and the transverse process, termed the mamillo-accessory ligament (MAL) (see image below).

The MAL is so named because it adjoins the mamillary process of the superior articular process to the accessory process of the transverse process (see image below). The MAL is clinically important because it allows precise location of the medial branch of the dorsal ramus using only bony landmarks, which is essential for fluoroscopically guided procedures.

After passing underneath the MAL, the medial branch of the dorsal ramus gives off 2 branches to the nearby Z-joints. One branch innervates the Z-joint of that level, and the second branch descends caudally to the level below. Therefore, each medial branch of the dorsal ramus innervates 2 joints—that level and the level below (eg, the L3 medial branch innervates the L3-L4 and L4-L5 Z-joints). Similarly, each Z-joint is innervated by the 2 most cephalad medial branches (eg, the L3-L4 Z-joint is innervated by the L2 and L3 medial branches). Some authors have also suggested that the L5-S1 Z-joint has a unique triple innervation; in addition to the expected innervation by the L3 and L4 medial branches, the S1 medial branch emerging from the S1 posterior sacral foramen ascends cranially to also innervate the L5-S1 Z-joint. This has not, however, been consistently reported.

Understanding of this anatomy is crucial for procedures that attempt to obliterate Z-joint–mediated pain by blunting the innervation, whether through anesthesia (eg, a medial branch block) or denervation (eg, medial branch radiofrequency ablation [RFA]).[16] Practitioners commonly make the mistake of thinking that each Z-joint is innervated by the 2 adjoining medial branches (eg, that the L4-L5 Z-joint is innervated by the L4 and L5 medial branches of the dorsal rami, when it is actually innervated by the L3 and L4 medial branches). Two common reasons are cited for why practitioners make this mistake.

First, in the cervical region, the Z-joints are innervated by the 2 medial branches of the same name (eg, the C3-C4 Z-joint is innervated by the C3 and C4 medial branches), with the transition occurring at the T1-T2 Z-joint, which is innervated by the C8 and T1 medial branches. The second reason practitioners commonly confuse the innervation pattern is because they fail to recognize that the medial branch descends one level to reach the Z-joint. For example, the L2 medial branch courses around the L3 superior articular process, crosses underneath the L3 MAL, and then sends branches to the L2-L3 and L3-L4 Z-joints. Therefore, in a medial branch block, the medial branches closest to the Z-joint are targeted; they simply descended from a higher level.

Moreover, it is important to note that the medial branch of the posterior rami also innervates other posterior back structures. This has several important clinical implications. First, pain relief from anesthetizing the medial branch does not necessarily implicate the Z-joints as the primary pain generator, because one of the other structures innervated by the medial branch may have been the pain generator. Second, denervation of the medial branch by RFA may affect the nerve supply to the multifidus muscle. This is important because lumbosacral radiculopathy is often another consideration in the differential diagnosis of LBP.

One test to confirm the diagnosis of a lumbosacral radiculopathy is electromyography (EMG) of the multifidus muscle. Normally, denervation potentials in the multifidus muscle of a patient with LBP might be interpreted as evidence of a lumbosacral radiculopathy. However, in the context of a patient who has had RFA of the medial branch of the dorsal rami for the treatment of Z-joint pain, an alternative explanation for the denervation potentials in the multifidus would be denervation from the RFA, not from a lumbosacral radiculopathy.

The Z-joints contain nociceptive nerve fibers from nerves of the sympathetic and parasympathetic ganglia, which can be activated by local pressure and capsular stretch. Nociceptive type IV receptors have been identified in the fibrous capsule and represent a plexus of unmyelinated nerve fibers and type I and II corpuscular mechanoreceptors. In addition, encapsulated type I and II nerve endings have been found to be primarily mechanosensitive and likely provide proprioceptive and protective information to the central nervous system.

In addition, the Z-joints have been found to undergo sensitization of neurons by naturally occurring inflammatory mediators such as substance P and phospholipase A2. Peripheral nerve endings release chemical mediators such as bradykinin, serotonin, histamine, and prostaglandins, which are noxious and can cause pain. Substance P has been implicated because of its ability to act directly on nerve endings or indirectly through vasodilation, plasma extravasation, and histamine release. Phospholipase A2 hydrolyzes phospholipids to produce arachidonic acid, causing an inflammatory reaction, edema, and prolonged nociceptive excitation.

In all, many sources of pain can be found at the Z-joint, ranging from degenerative changes to irritated nerve endings (chemical and mechanical) to concomitant nerve root entrapment.

Related Medscape Reference topics include the following:

• Herniated Nucleus Pulposus

• Lumbosacral Disc Injuries

• Lumbosacral Spine Acute Bony Injuries

• Lumbosacral Spine Sprain/Strain Injuries

• Lumbosacral Spondylolisthesis

• Lumbosacral Spondylolysis

• Spinal Stenosis

Athletes involved in nearly any type of sport are susceptible to Z-joint injury. From linemen on a football team, who may sustain repetitive and compressive forces to an extended spine, to baseball players or golfers, who perform repeated spinal rotational maneuvers, lumbosacral facet syndrome can impact athletes in most sports.

Related Medscape Reference topics include the following:

• Degenerative Lumbar Disc Disease in the Mature Athlete

• Lumbar Disk Problems in the Athlete

Establishing a diagnosis of lumbosacral facet syndrome is difficult because the findings are nonspecific and correlation between the history and physical examination findings is poor. However, obtaining a detailed history and performing a physical examination help rule out other entities and assist with guiding the examiner in establishing the diagnosis of Z-joint–mediated LBP.

Although no single sign or symptom is diagnostic, Jackson et al demonstrated that the combination of the following 7 factors was significantly correlated with pain relief from an intra-articular Z-joint injection[17] :

• Older age

• Previous history of LBP

• Normal gait

• Maximal pain with extension from a fully flexed position

• The absence of leg pain

• The absence of muscle spasm

• The absence of exacerbation with a Valsalva maneuver

A basic demographic history should be taken. In particular, because most Z-joint pain is related to degenerative changes, older age may be related to Z-joint pathology.

The basic history should include a temporal account of the symptoms, a complete description of the problem, and a discussion of the associated activities that cause or alleviate the pain. The patient should describe the location of the pain; state whether it is isolated or radiating; and relate its intensity, character, and frequency. Red flags (ie, symptoms or signs that stand out as highly suggestive) that should be seriously scrutinized include the presence of unexplained weight loss, fever, and chills. The clinician should also obtain a history of any previous treatments (eg, injections, medications, therapy) and whether they were successful.

Z-joint pathology should be considered if the patient describes nonspecific LBP with a deep and achy quality that is usually localized to a unilateral or bilateral paravertebral area.

Provocative injections of the Z-joints have been used to create a sclerotomal map of the Z-joint’s pain referral pattern. Based on these studies, the common referral areas for Z-joint–mediated pain are flank pain, buttock pain (often extending into the posterior thigh, but rarely below the knee), pain overlying the iliac crests, and pain radiating into the groin. However, this pain pattern is not consistently reported in patients with Z-joint pain as confirmed by diagnostic intra-articular Z-joint injections. Therefore, this sclerotomal representation of the Z-joint is only suggestive, not diagnostic.

The pain is often exacerbated by twisting the back, by stretching, by lateral bending, and in the presence of a torsional load. Some patients describe their pain as worse in the morning, aggravated by rest and hyperextension, and relieved by repeated motion. Often, this lumbosacral facet syndrome may occur after an acute injury (eg, extension and rotation of the spine), or it may be chronic in nature.

Unlike other lumbar spine pathologies such as disc herniation, Z-joint–mediated pain likely will not worsen with an increase in intra-abdominal and thoracic pressure. Therefore, worsening of pain with coughing, laughing, or a Valsalva maneuver is suggestive that the Z-joint is not the primary pain generator.

No historical findings or examination maneuver is unique or specific to Z-joint–mediated LBP. In fact, some authors report up to a 45% false-positive rate when the physical examination findings are correlated to diagnostic medial branch blocks of the posterior rami. Many clinicians agree that correlating history or physical examination findings with pain emanating from the Z-joint is a challenge.

Patients with Z-joint–mediated LBP usually have nonspecific history and physical examination findings. An in-depth evaluation of the neurologic and musculoskeletal systems helps exclude other diagnoses and guides the clinician to possible Z-joint pathology.

Inspection

Inspection should include an evaluation of paraspinal muscle fullness or asymmetry, increase or decrease in lumbar lordosis, muscle atrophy, or posture asymmetry.

Patients with chronic facet syndrome may have flattening of the lumbar lordosis and rotation or lateral bending at the sacroiliac joint or thoracolumbar area.

Palpation

The examiner should palpate along the paravertebral regions and directly over the transverse processes because the Z-joints are not truly palpable. This is performed in an attempt to localize and reproduce any point tenderness, which is usually present with Z-joint–mediated pain.

In some cases, Z-joint–mediated pain may radiate to the gluteal or posterior thigh regions.

Range of motion

Range of motion should be assessed through flexion, extension, lateral bending, and rotation.

With Z-joint–mediated LBP, pain is often increased with hyperextension or rotation of the lumbar spine, and it might be either focal or radiating.

Flexibility

Inflexibility of the pelvic musculature can directly impact the mechanics of the lumbosacral spine.

With Z-joint pathology, the clinician may find an abnormal pelvic tilt and rotation of the hip secondary to tight hamstrings, hip rotators, and the quadratus, but these findings are nonspecific and can be found in patients with other causes of LBP.

Sensory examination

Sensory examination (ie, light touch and pinprick in a dermatomal distribution) findings are usually normal in persons with Z-joint pathology.

Muscle stretch reflexes

Patients with Z-joint–mediated LBP usually have normal muscle stretch reflexes. Radicular findings are usually absent unless the patient has nerve root impingement from bony overgrowth or a synovial cyst.

Side-to-side asymmetry should lead one to consider possible nerve root impingement.

Muscle strength

Manual muscle testing is important to determine whether weakness is present and whether the distribution of weakness corresponds to a single root, multiple roots, or a peripheral nerve or plexus.

Typically, manual muscle testing results are normal in persons with Z-joint pathology; however, subtle weakness of the muscles of the pelvic girdle may contribute to pelvic tilt abnormalities. This subtle weakness may be appreciated with trunk, pelvic, and lower-extremity extension asymmetry.

Straight leg – raise test

This maneuver is usually normal for Z-joint–mediated pain. However, if Z-joint hypertrophy or a synovial cyst encroaches on the intervertebral foramen, causing nerve root impingement, this maneuver may elicit a positive response.

Laboratory studies are not generally necessary for the diagnosis of lumbosacral facet joint syndrome.

Plain radiography

Plain radiographs are traditionally ordered as the initial step in the workup of lumbar spine pain. The main purpose of plain films is to determine underlying structural pathologic conditions. These studies are not generally recommended in the first month of symptoms in the absence of red flags. An exception to this would be if the low back symptoms are related to a sports injury and a fracture is suggested.

Three views are commonly obtained, including an anteroposterior (AP), lateral, and oblique; however, the utility of oblique views has been questioned.

Plain radiographs may reveal degenerative changes, but these findings have not been found to correlate with Z-joint–mediated pain.

Bone scanning

Bone scanning can be helpful when a tumor, infection, or fracture (occult or traumatic) is suggested.

Bone scanning is not usually indicated in the initial workup, and the results are normal in persons with lumbosacral facet joint syndrome.

Bone scan findings have not been found to correlate with Z-joint–mediated pain.

Computed tomography (CT) scanning

Generally, CT scanning is not necessary unless other bony pathology (eg, fracture) must be excluded.

A CT scan of the lumbosacral spine provides excellent anatomic imaging of the osseous structures of the spine, especially to rule out fractures or arthritic changes. Single-photon emission CT (SPECT) images may offer better resolution if spondylolysis is suggested.

With Z-joint pathology, one may find arthritic changes in the Z-joints and degenerative disc disease; however, Z-joint pathology is also frequently seen in asymptomatic patients, and, therefore, abnormal findings on a CT scan are not diagnostic.

Despite the excellent imaging of the bony anatomy of the Z-joint, CT scans are not useful for the diagnosis of the Z-joint as a pain generator. For example, Schwarzer et al found no correlation between Z-joint pathology on a CT scan and those patients who responded to diagnostic Z-joint blocks.[7] Therefore, the correlation of an abnormal Z-joint anatomy as observed on CT scans with true Z-joint–mediated pain is poor.

Magnetic resonance imaging (MRI)

In general, MRI is not indicated for the evaluation of nonradicular LBP.

The main utility of MRI is for excluding pathologies other than Z-joint arthropathy, because many degenerative changes in the Z-joint are asymptomatic. Similarly, true Z-joint–mediated pain may be present despite a normal MRI examination.[18]

MRI provides detailed anatomic images of the soft structures of the spine, such as the intervertebral discs, which often show degenerative changes before Z-joint pathology.[19]

MRI also may illustrate nerve root entrapment secondary to Z-joint hypertrophy or a synovial cyst and may help visualize the intervertebral foramen; however, Z-joint pathology may be present despite normal imaging study findings.

MRI is particularly useful for the evaluation of a synovial cyst emanating from a Z-joint and for distinguishing a synovial cyst from other abnormalities. Gadolinium enhancement is useful in the evaluation of a potential synovial cyst. Also helpful is to make the radiologist aware that a synovial cyst is part of the differential diagnosis because this entity is often overlooked.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the Medscape Reference topic Nephrogenic Systemic Fibrosis.

NSF/NFD has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. As of late December 2006, the FDA had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Electrodiagnosis

Electrodiagnostic studies, such as nerve conduction studies and needle EMG, are not usually indicated for possible lumbosacral facet syndrome. However, these studies should be considered if the history and physical examination findings suggest nerve root impingement or if the diagnosis remains unclear.

Persons with Z-joint pathology typically present with normal sensory and motor examination findings; however, some patients describe the pain as radiating in nature and others report a positive straight leg – raise test result. Thus, electrodiagnostic testing may be helpful for excluding other causes of pain, such as radiculopathy.

RFA of the medial branch of the dorsal ramus affects the innervation of not only the Z-joint, but also the multifidus muscle. Normally, denervation potentials in the multifidus muscles in the setting of LBP are most commonly associated with lumbosacral radiculopathy. In the setting of a patient who has had previous RFA, however, the denervation potential is likely secondary to denervation from the procedure and not a radiculopathy.

Medial branch block

Given that no historical or physical examination maneuver is unique or specific to Z-joint–mediated LBP, fluoroscopically guided medial branch nerve injections are often used for diagnostic purposes to determine whether the Z-joint in question is responsible for LBP. Once the Z-joint is established as the pain generator, more definitive treatment options, such as radiofrequency ablation, are offered. A Z-joint injection may also be used for therapeutic purposes, but many consider this procedure more challenging to perform.

Given the dual innervation of each Z-joint, one must anesthetize or block the cephalad and subadjacent medial branches (eg, anesthetize the L3 and L4 medial branches for the L4-L5 Z-joint). Injections are diagnostic if patients report significant relief of symptoms, usually at least a 50% reduction in pain. Although the optimal number of blocks prior to radiofrequency denervation is uncertain, most guidelines, including the Spine Intervention Society (SIS) and the North American Spine Society (NASS), recommend a positive response to 2 screening medial branch blocks with at least 80% relief on 2 occasions for radiofrequency ablative denervation  to be done.[20]

Rehabilitation Program

Physical Therapy

The initial treatment plan for acute Z-joint pain is focused on education, relative rest, pain relief, maintenance of positions that provide comfort, exercises, and some modalities. Physical therapy includes instruction on proper posture and body mechanics in activities of daily living that protect the injured joints, reduce symptoms, and prevent further injury. Positions that cause pain (eg, extension, oblique extension) should be avoided. Bed rest beyond 2 days is not recommended because this can have detrimental effects on bone, connective tissue, muscle, and the cardiovascular system. Thus, activity modification, rather than bed rest, is strongly recommended.

Modalities such as superficial heat and cryotherapy may also help relax the muscles and reduce pain. In addition, medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) may also be administered. Spinal manipulation and mobilization may also be attempted to reduce pain.

Surgical Intervention

Surgical intervention is not the first-line treatment for the management of LBP, including Z-joint–mediated pain, and the vast majority of patients with LBP improve without surgery. Some circumstances, however, dictate that surgical evaluation is indicated. For example, loss of bowel or bladder function or saddle anesthesia (ie, decreased sensation of the perineal region, such as loss of the ability to feel toilet paper touching the skin) are particularly concerning and require emergent surgical evaluation.

Other red flags that may necessitate surgical evaluation include signs and symptoms of malignancy (eg, rapid, unintended weight loss; cancer history; night pain; radiologic findings), unexplained fever, or rapidly progressing neurologic deficits. Importantly, the practitioner must be alert to these ominous signs (red flags) because they can manifest even later in the course of managing a patient’s LBP.

Other Treatment

Spinal manipulation may be useful for both short- and long-term pain relief. Some evidence supports the use of spinal manipulative therapy combined with a trunk-strengthening program, which, over the course of a year, may actually reduce the need for pain medication.

While radiofrequency ablation for the treatment of general low back pain is controversial, one area that it seems to have better outcomes is lumbar facet syndrome. A study that investigated function, pain, and medication use outcomes of radiofrequency ablation for lumbar facet syndrome demonstrated a durable treatment effect of radiofrequency ablation for lumbar facet syndrome at long-term follow-up, as measured by improvement in function, pain, and analgesic use.[21]  

A study by Juch et al reviewed three randomized clinical trials that evaluated the effectiveness of radiofrequency denervation in 681 total patients with chronic low back pain and who were unresponsive to standard treatment (251 patients in the facet joint trial, 228 in the sacroiliac joint trial and 202 patients in a combination of facet joints, sacroiliac joints, or intervertebral disks trial). The study reported no clinically important improvements in patients from radiofrequency denervation combined with a standardized exercise program compared with a standardized exercise program alone.[22]

 

Rehabilitation Program

Physical Therapy

Once the painful symptoms are controlled during the acute phase of treatment, stretching and strengthening exercises of the lumbar spine and associated muscles can be initiated.

Because Z-joint–mediated pain tends to be worse with extension, strengthening and conditioning exercises should typically be performed with a flexed trunk. Strengthening maneuvers must emphasize flexion, neutral postures, and pelvic tilt, all in an effort to reduce compression of the Z-joints.

Another therapeutic goal is to reduce the lumbar lordosis because excessive lordosis increases the loading on the posterior elements, including the Z-joints. Therefore, the patient should be taught pelvic tilt maneuvers to reduce the degree of lumbar lordosis. Pelvic tilt maneuvers can be taught in multiple positions (with knees bent while standing, legs straight while standing, and while sitting) to emphasize proper posture in multiple planes. Flexion-based exercises should be avoided in the presence of hypermobility or instability or if the maneuvers increase LBP.

Similarly, stretching exercises should be focused on restoring proper pelvic tilt; therefore, special emphasis should be placed on stretching those muscles that cause excessive anterior pelvic tilt (eg, the hip flexors and lumbar extensors). Stretching should be not limited to just these muscles because all the muscles attaching to the lumbar spine and pelvic girdle may be in imbalance, and regular stretching can help restore normal motion to the lumbar spine and pelvis. Therefore, stretching programs should also include stretches of the hamstrings, quadriceps, hip abductors, gluteals, and abdominals. Stretching through dynamic postural motions (eg, yoga postures) can be especially helpful because the motions can restore balance to the muscles of the lumbar spine and pelvic girdle.

These exercises are eventually incorporated into a more comprehensive rehabilitation program, which includes spine stabilization exercises. The goal with these exercises is to teach the patient how to find and maintain a neutral spine during everyday activities. The neutral spine position is specific to the individual and is determined by the pelvic and spine posture that places the least stress on the elements of the spine and supporting structures. Bridges and planks are ideal exercises for this as they can be done in the neutral spine position with high muscle activation and relatively low spinal loads. McGill recommends work up to 1 rep at 60 sec holds to build the necessary endurance for optimum spine function.[23]

Dynamic lumbar control is also incorporated to protect the spine from biomechanical stresses, including tension, compression, torsion, and shear. Spinal stabilization emphasizes synergistic activation of the trunk and spinal musculature in the midrange position by strengthening the abdominal and gluteal muscles and enables the patient to develop the muscles that support the trunk and spine and, ultimately, diminish the overall stress on the spine.

Not all patients have the same flexibility and strength imbalances. Individual, detailed assessment by an experienced physical therapist may allow for a tailored therapeutic program.

Other Treatment (Injection, manipulation, etc.)

Three fluoroscopically guided spinal injections are often used in the diagnosis and management of Z-joint pain, although their efficacy remains in question. The goal of Z-joint injections is to facilitate a physical therapy program; therefore, their utility is primarily to verify the diagnosis and perhaps reduce pain to make the patient’s physical therapy program more successful. If previous injections were helpful and pain recurs, injections can be repeated; however, they should be limited.

Single injections with a local anesthetic have high false-positive rates (38%). Therefore, when performing any interventional injection, the criterion standard is to use a double- or triple-block paradigm. In a double-block protocol, the patient is given an injection with a short-acting anesthetic (eg, lidocaine) and records the duration of pain relief in a diary. On a follow-up visit (typically 1-2 wk later), a second injection is performed, using an anesthetic with a different duration of action (eg, bupivacaine, which has a longer half-life than lidocaine), and the patient again should chart pain relief in a diary. A patient is diagnosed as having a positive block if they receive pain relief (typically >80%) for both injections for a length of time corresponding to the duration of action of the medication.

For additional diagnostic accuracy, a third block can be performed with saline, although this is rarely performed in clinical practice. The diagnostic reliability of double- and triple-block protocols is clearly superior to that of a single-block protocol; therefore, these should be used before performing an ablation procedure or surgery.

Intra-articular Z-joint injection with corticosteroids and a local anesthetic can also be performed.[24, 25, 26, 27, 28, 29] Typically, this is performed under fluoroscopic guidance with contrast medium. Intra-articular anesthetic injections are considered the most accurate method for diagnosing Z-joint–mediated pain, particularly when performed with a double- or triple-block protocol.

Some have questioned, however, whether intra-articular corticosteroids are as effective in relieving Z-joint–mediated pain as other options, namely RFA of the medial branch of the dorsal ramus.[30, 31, 32] Additionally, injections into the Z-joint are often technically difficult because of joint degeneration and bony overgrowth. The main advantage of intra-articular injections, then, is not so much in its efficacy, but rather that it allows the practitioner to offer a potentially therapeutic injection at the same time as the diagnostic injection (as opposed to RFA, which is preferably performed after a double- or triple-block diagnostic protocol, and thus requires at least 3 separate injections).

Proietti et al aimed to evaluate the effectiveness of facet joints injections in lumbar facet syndrome correlating clinical results to the sagittal contour of the spine. Only patients with thoracolumbar kyphosis and short hyperlordosis (Type I Rossouly classification) showed significant improvement in pain at 3 month follow-up. For other classifications, facet joint injections provided only a temporary pain relief and should be reserved for diagnostic use.[33]

The long-term benefit of intra-articular injection remains controversial, and some studies have reported similar results with either steroids or saline injection.

Complications are rare, although tenderness at the injection site is reported. A few reports have noted spinal block, vasovagal episodes, and chemical meningitis due to puncturing of the dural cuff, but these reports are rare. Recommend that patients withhold medications that promote bleeding, such as NSAIDs, warfarin (Coumadin), and aspirin. However, recent guidelines from the NASS have noted that the risk of MI or stroke in stopping these medications is much greater than the risk of bleeding in the soft tissues of the lumbar spine. Contraindications include bacterial infection, possible pregnancy, bleeding diathesis, and local anesthetic allergy.

Medial branch block for diagnostic purposes has already been described (see Workup, Procedures), and studies have shown it to be effective in this regard; however, controversy remains regarding its use as a therapeutic intervention. Note that such a block also eliminates pain that may be emanating from other structures that are innervated by the medial branch, such as the multifidus or interspinous muscles or the interspinous ligaments.

An alternative to medial branch block denervation was studied by Iwatsuki et al in 21 patients with lumbosacral facet syndrome.[34] These investigators evaluated the use of laser denervation to the dorsal surface of the facet capsule. At 1-year postprocedure, 17 patients (81%) experienced complete or greater than 70% pain reduction, whereas 4 patients (19%) had unsuccessful therapy.[34] Iwatsuki et al suggested that the dorsal surface of the facet capsule might be a more preferable target for facet denervation.

A third intervention involves a medial branch neurotomy through RFA, chemical neurolysis, or cryoneurolysis. Percutaneous radiofrequency neurotomy is a method of denaturing the nerves that innervate the Z-joint through coagulation, thus resulting in more prolonged pain relief.[35, 36] Medial branch neurotomy through RFA has emerged as the standard therapy for facet-mediated low back pain.[20] When performing these procedures, remember that the radiofrequency signal spreads circumferentially from the shaft and not linearly from the tip of the transducer; therefore, the shaft of the transducer must be placed parallel to the medial branch (as opposed to when performing a medial branch block, in which the tip should be aimed at the medial branch because the anesthetic leaves the tip of the needle and not the shaft). Once the axons regenerate, pain often returns.

The therapeutic benefit of this procedure likewise remains controversial[30, 37, 38] ; however, success rates range from 17-90% for periods of 6-12 months. Many of the studies have poor selection criteria, inconsistent techniques, poor outcome measures, and small sample sizes.

Related Medscape Reference topics:

• Corticosteroid Injections of Joints and Soft Tissues

• Therapeutic Injections for Pain Management

Rehabilitation Program

Physical Therapy

The maintenance phase represents the final phase of the rehabilitation process for lumbosacral facet syndrome. Eccentric muscle-strengthening exercises, including more dynamic conditioning exercises (eg, with a large gym ball) are added to the program. Exercises are to be performed in a functional manner and in functional planes (eg, standing in multiple planes). For patients involved in sporting activities, sports-specific training is incorporated so that a neutral spine can be maintained. The goals of a comprehensive spine rehabilitation program have been met when pain is controlled, near-full range of motion of the spine is achieved, symmetrical flexibility is attained, and trunk control can be maintained in sport or recreational activities.

Other Treatment

Spinal manipulation is being used for both short- and long-term pain relief. Some evidence supports the use of spinal manipulative therapy combined with a trunk-strengthening program, which, over the course of a year, may actually reduce the need for pain medication.

Various medications are used in the treatment of LBP secondary to the degenerative changes often observed in Z-joint dysfunction. These include acetaminophen, NSAIDs, muscle relaxants, opioid analgesics, and antidepressants. Before prescribing these medications, the physician should be aware of the contraindications, common adverse effects, and mode of action of each agent.

Related Medscape Reference topics include the following:

• Acetaminophen Toxicity

• Antidepressant Toxicity

• Opioid Toxicity

• Nonsteroidal Anti-inflammatory Agent Toxicity

Class Summary

NSAIDs offer anti-inflammatory benefits compared with acetaminophen. The dose needed to achieve an anti-inflammatory benefit is significantly greater than that needed for an analgesic effect. Risks are associated with NSAIDs, especially in elderly persons or persons with peptic ulcer disease, hypertension, or renal insufficiency. Newer-generation NSAIDs selectively interact with the cyclooxygenase (COX)-2 receptors and have a lower GI risk. Prolonged use of these medications is generally not recommended for most low back dysfunctions.

Ibuprofen (Ibuprin, Motrin, Advil)

DOC for mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Class Summary

Muscle relaxants may be helpful in some patients with LBP and may offer additional benefit when used with NSAIDs. These agents can be used as short-term adjunctive medications and should be taken at bedtime to take advantage of the sedating effects.

Cyclobenzaprine (Flexeril)

Skeletal muscle relaxant that acts centrally and reduces motor activity of tonic somatic origins, influencing both alpha and gamma motor neurons. Structurally related to TCAs and thus carries some of their same liabilities.

Class Summary

Opioid analgesics should be limited to pain that is unresponsive to alternative medication. These agents can be prescribed for acute facet syndrome to facilitate participation in an active rehabilitation program, and they should be used on a defined dosing schedule rather than prn. In addition, an adequate baseline dose should be established to achieve analgesia. Long-acting opioids should be considered in patients who require an opioid for greater than 1-2 weeks.

Oxycodone (OxyContin, OxyIR, Roxicodone)

Indicated for moderate to severe pain.

Class Summary

Tricyclic antidepressants (TCAs) can be used as an adjunctive treatment for pain and sleep if they are taken at bedtime. The initial doses should be low, and subsequent doses can be slowly increased to minimize adverse effects.

Amitriptyline (Elavil)

Inhibits reuptake of serotonin and/or norepinephrine at presynaptic neuronal membrane, which increases the concentration in the CNS. Analgesic for certain chronic forms of pain.

Class Summary

These agents are a complex group of drugs that inhibit serotonin and norepinephrine reuptake. Some drugs in this class are weak inhibitors of dopamine reuptake with sedative effects.

Duloxetine (Cymbalta)

Duloxetine can be used for chronic musculoskeletal pain or low back pain. It is a potent inhibitor of neuronal serotonin and norepinephrine reuptake.

Athletes who demonstrate lumbosacral Z-joint pathology should remain out of their sport until they regain full, pain-free range of motion and are able to complete sport-specific training without discomfort. They should also have symmetrical flexibility and be able to maintain trunk control throughout sporting activities to prevent recurrence.

In some cases, lumbosacral facet syndrome can lead to chronic pain, time lost from employment or sports, and disability. Interventional procedures, such as Z-joint injections with anesthetics and corticosteroids, can lead to transient lower-extremity weakness, insomnia, headache, fluid and electrolyte disorders (especially in patients with congestive heart failure), GI upset, bone demineralization, and impaired glucose tolerance (patients with diabetes). Less common effects are mood swings, increased appetite, and, the most serious, adrenocortical insufficiency. Dural puncture can lead to infection and an increased incidence of headaches.

Instruction should be provided to the patient on proper posture, activity modification, and body mechanics in activities of daily living and sports. This helps protect the injured joints, reduce symptoms, and prevent further injury. Positions that cause pain should be avoided.

With an active and focused spine rehabilitation program, the prognosis for these patients to achieve pain-free activity is good; however, the definitive diagnosis of Z-joint pathology is often difficult to make and challenging to confirm. For some patients, LBP may persist, and more aggressive interventions beyond conservative rehabilitation should be considered. Interventions such as medial branch blocks or neurolysis remain controversial, but they should be given consideration in the event conservative treatment remains inadequate and all other sources of LBP have been investigated.

Patient education is important for the recovery and rehabilitation of the spine in patients with lumbosacral facet syndrome. In the acute stage, patients must have a good understanding of their condition and of the possible detrimental effects of prolonged bed rest (ie, >2 d). Instruction in proper posture and body mechanics with activities of daily living is very important for these individuals. As pain becomes more controlled, the patient must be active in a progressive spine rehabilitation program, which later should be incorporated into a home exercise program for continued functional strengthening. Back safety and joint protection strategies should be incorporated throughout the rehabilitation process.