by Chris Cheung
Facet joint hypertrophy is an enlargement of the posterior articular processes between adjacent vertebrae and occurs when they become enlarged due to degenerative changes. This enlargement can cause compression of nerves and other structures in the area, which can create localized pain in the neck or back and radiating pain to other parts of the body, leading to functional impairments.
The vertebral column consists of 24 vertebrae and a fused sacral and coccygeal region, each articulating with the vertebra above and below. A vertebra can be divided into two sections: an anterior section, which is the vertebral body, and a posterior section, which is the vertebral arch. The two sections are held together by pedicles. The vertebrae are connected posteriorly by two superior articular facets and two inferior articular facets. The superior articulations of a vertebra form a facet joint with the inferior articulations of the vertebra above. These joints are also called zygapophyseal or apophyseal joints. Because these joints are synovial joints, they are surrounded by a joint capsule and lined with articular cartilage inside. The space within the joint is filled with synovial fluid and the outside is innervated by the medial and lateral branches of the dorsal primary rami1. The articular surfaces of facet joints are usually flat, but become slightly curved in the upper cervical and lumbar regions. The superior facets are usually formed in a concave manner, allowing the convex surface of the inferior facet to fit congruently2. Depending on the orientation of the articulations, each joint allows different types of movements and restricts others. In general, facets oriented in a horizontal direction allow for axial rotation. Cervical facets are oriented in this manner. Those in the vertical direction allow for flexion, extension, and lateral flexion. This includes thoracic facets, which are oriented in the frontal plane, and lumbar facets in the sagittal plane. In reality, most facet joints are oriented between a horizontal and vertical plane, and therefore allow for some movement in each direction1.
Motion within the intervertebral complex occurs at the facet joints, vertebral bodies and the intervertebral disc. Hypertrophy of the facets occurs mostly in the lumbar and cervical regions, but rarely in the thoracic level. Studies show that the facets between L3-4, L4-5, and L5-S1 experience the greatest amount of stress with forward and lateral flexion. This predisposes those areas to experience an increased amount of repetitive strain and inflammation, which can lead to facet hypertrophy and other degenerative changes3. Therefore, hypertrophy of facets occurs primarily as a result of other degenerative processes. A dysfunction in one area will eventually cause damage in other parts of the complex.
Facet joints are primarily responsible for guiding the movements of the vertebral column and are vulnerable to damage caused by increased forces and repetitive movements. Increased forces on the facets creates additional loading on the joints and compresses the two articular surfaces together. The constant strain on these joints begins an inflammatory process, which thickens the joint capsule and decreases the movement allowed at that joint. Trauma at the level of the facet also initiates the inflammatory process, leading to hypertrophy4.
The increased compression in the facets also causes damage to the articular cartilage in the joint. As the deterioration of cartilage progresses, osteoarthritis begins to develop in the facet joints and the impact of the bones against each other causes development of bony projections called ostephytes. This additional bone growth can cause further damage to the remaining cartilage in the joint3.
Damage to the intervertebral discs can also lead to degenerative changes in the facet joints. As the fibers of the disc weaken and the nucleus pulposus herniates out the sides of the disc, the height of the disc also decreases. As a result, the vertebral bodies come into contact when the spine goes into flexion and extension, causing an increase in the load placed on the facet joints. The decrease in disc space also brings the facets closer in contact, creating the increased amount of physical stress placed the facets and causing hypertrophy of the joint to develop5. Any alterations in the position of the posterior elements of the vertebra can lead to situations where facet joints become hypertrophied. The facets can sublux, causing abnormal sliding movements that lead to hypertrophy4. A decreased disc height can also shift the axis through which the spinal segments rotate. The axis of roation for flexion and extension normally occur through the disc, but with the decrease in disc space, the axis changes to go through the facet joints, increasing the damage to that area1. Osteoarthritis of the facet joints is also seen with disc degeneraton3.
Hypertrophy of the facets can cause stenosis in the spinal canal or the area where spinal nerve roots exit. Marzluff et al. performed a study on thoracic stenosis and found that each case was caused by facet hypertrophy6. Choudhury and Taylor discovered similar findings in 28 patients who had radicular pain and other symptoms. Each one of these patients had stenosis of the lateral recess due to facet hypertrophy which compressed the nerves as they came out of the intervertebral foramen, causing pain to radiate down the legs4. Radiating pain due to nerve root entrapment can be confused with disc herniations, as the symptoms of both are similar. Hypertrophy of the facet joints can also irritate branches of the dorsal rami, which creates pain in the joint and referred down the leg1. Radiation of symptoms primarily occurs unilaterally, but occasionally bilateral symptoms can appear4.
In the study performed by Choudhury and Taylor, the most common symptom exhibited by the subjects with facet hypertrophy was a long history of low back pain. The pain began intermittently and progressed to a more chronic pain. Some subjects also had radiating pain down the legs, mostly on one side of the body. Because of the pain, the subjects had restricted back mobility4.
The various symptoms of facet hypertrophy are determined through different methods. CT scans and MRI are more useful to view the hypertrophy of the facets7, while nerve blocks can determine if nerve root entrapment is present and which levels are affected8. Changes in the facets can be seen on any radiographs, but CT scans are preferred over MRIs. CT scans can locate the level of degeneration and the extent of the damage8. To test if a facet is the source of pain the patient is experiencing, facet joint blocks can be used through intraarticular injections at a specific level or anesthetizing the medial branches of the dorsal rami, which innervate the facet joint. A true positive response will be a short duration of pain relief when a short-acting agent is injected, and a long duration of relief with a long-acting agent. False positives are guarded against by observing the injection on a radiograph to ensure that the injection is only localized to one level. Cervical and lumbar injections have been demonstrated to have good face validity9.
Relief for pain and other symptoms of facet hypertrophy can be achieved from direct injection of corticosteroids and anesthetics, such as lidocaine and bupivacaine, into the joint. A fluoroscopic radiography is used to ensure that the injection is made into the correct joint level to decrease inflammation and pain9. In one study on facet blocks, 74% of the subjects had immediate relief of their symptoms and 33% had a relief for over 3 months10.
The purpose of injections is to relieve the pain and inflammation so that other forms of treatment can be used. Physical therapy is another form of conservative treatment for facet hypertrophy, with the goal of reducing pain and restoring function. The joints in the back need movement of fluid and nutrients in and out of the joint space. Mobilizations on the affected spinal level can achieve this, in addition to relieving the pain and compression in the joint. Physical therapists can also use modalities such as heat, ice, electrical stimulation and ultrasound to help relieve pain. Exercises are also important for regaining flexibility and strengthening core muscles that control the movement of the vertebrae and ensure proper alignment of the joints9.
The standard surgical procedure for facet hypertrophy is a surgical decompression with instrumented fusion11. One method of decompression is decompressive laminectomy. This procedure was performed by Katz et al. on 88 patients presenting with lumbar stenosis. In their procedure, surgeons decompressed the spine through the removal of the lamina at the level where symptoms presented. Lateral recesses were decompressed through a medial facetectomy and nerve roots were decompressed along their path through the intervertebral foramen. Additional fusion of the vertebrae with bone from the iliac crest was performed on older patients with spondylolisthesis. Three years after the procedure, it was observed that subjects who with additional co-morbidities, such as arthritis and cardio-pulmonary diseases, demonstrated poorer outcomes. Seventeen percent of the subjects had a repeat operation and 30% had severe pain12.
The subjects in the study done by Choudhury and Taylor underwent a similar procedure called “wide laminectomy.” Each patient had compression of nerve roots in the lateral recess due to hypertrophy of a facet joint. In the procedure, decompression was achieved through removal of the lamina. The excision was extended more laterally to include the part of the facet covering the lateral recess, so that the nerve roots could be accessed for removal of surrounded scar tissue and adhesions. Twenty-four of the 28 patients had complete resolution of their symptoms and were able to return to normal activity4. However, because it was been seen that surgical decompression with fusion restricts spinal mobility and the procedure has a re-operation incidence of 20%11, people have looked to other methods of relieving spinal stenosis caused by facet hypertrophy.
A novel method of correcting facet joint dysfunctions is through a facet arthroplasty. If the lateral recess is being compressed, it can be decompressed by removing the facets and lamina, and replacing them with a metal device called a Total Facet Arthroplasty System (TFAS). The TFAS is shown to maintain the same mobility of the spine and the same load placed on the disc without creating adverse effects on the other spinal levels. In one study by Phillips et al., their observed normal ranges of motion at the L3-4 levels in subjects who used the TFAS model, whereas those who had fusion had an increased the amount of motion in the other segments to compensate for the lack of mobility in the fused segements. The TFAS model was able to equally distribute the motion through the entire spine13.
Other forms of surgical treatment include:
•Interspinous Process Decompression
Another treatment option that is available to physical therapists is the use of physical agents as an adjunctive therapy to their main treatment program. These include thermotherapy and cryotherapy, ultrasound and electrical stimulation. The purpose of these supplemental treatments is to lessen the severity of the symptoms of the patient is experiencing in order to make the primary treatments more tolerable and effective14.
Thermotherapy involves the application of heat, while cryotherapy is the application of cold to a specific part of the body. Heat is used to help control pain, increase tissue extensibility and improve blood flow in order to facilitate healing of tissues. Cold can be used to help control inflammation and edema, decrease pain, and reduce spasticity to increase movement. The purpose of these therapies in relation to facet hypertrophy is to decrease the symptoms the patient is experiencing, which is usually pain. In both cases, heat and cold affect the body’s perception of pain through the gate control theory. The cutaneous sensory receptors that perceive superficial temperature changes are stimulated by the heat or cold and transmit signals to the brain that block the signals from pain receptors and influence the body’s perception of pain. Another form of heat application is the use of ultrasound waves on a particular area of the body. Ultrasound can decrease pain through the gate control theory or by increasing soft tissue extensibility to decrease joint stiffness14.
Pain can also be decreased with the use of electrical stimulation superficially through the skin. This application of electrical stimulation at a comfortable intensity also works through the use of the gate control theory. It is called transcutaneous electrical nerve stimulation or TENS. Similar to TENS is the use of interferential currents (IFC), which delivers electrical currents from different circuits that produce a different frequency. It works on the same basis as TENS through the gate control theory14.
Mechanical traction is another method of pain relief that is available for physical therapists to relieve pain caused by facet hypertrophy. Traction applies a distraction force on the facet joint surfaces, reduces compression of joint spaces and opens up the intervertebral foraminal space to relieve the pressure on nerve roots. This can decrease the pain caused by a joint surface dysfunction, allowing for the patient to perform pain-free functional activities14.
Although the theory behind each of these modalities is sound and each are used frequently in physical therapy clinics, there is little evidence in the literature to support their use for back pain. Reviews of studies on each of these modalities demonstrated overall results that were not statistically significant or inconsistent and came from low quality studies15-20. A review done on the use of IFC for musculoskeletal pain was found to be a good supplemental intervention when done in combination with other treatments. However, it was unclear which of the two interventions was more effective in managing pain. It was shown however that the use of IFC alone was not more effective than a placebo or another form of treatment15. A Cochran review done on the use of heat and cold found moderate support for the short-term use of a blanket heat wrap to decrease pain and disability in populations with acute or subacute low back pain. However, there was insignificant evidence to support the use of heat or cold overall16. One study found that a combination of various treatments, including electrotherapy, heat, ultrasound, massage, and exercise therapy was effective in improving pain and function compared to a control group in patients with musculoskeletal dysfunctions. However, no specific combinations were specified to be more effective than others17. Overall, these studies demonstrated that there are no significant outcomes from the use of these physical agents to decrease pain and disability.
Although results from most studies do not support the use of traction to relieve back pain21-22, one study found significant results in the treatment of back pain due to facet dysfunction. Gose et al. found that of the 19 subjects with facet syndrome, their pain decreased from an average of 4 out of 5 to 1.13 out of 5. These subjects demonstrated a decrease in pain of 72%, with a success rate of 68%23.
Despite these positive results, more studies need to be done to provide a more conclusive stance on the effect of traction to relieve pain caused by facet hypertrophy and dysfunction. Larger high quality studies in this area can help determine the efficacy of traction of this patient population.
There are few studies done to examine the effects of modalities on facet hypertrophy or pain specifically. Most studies have been performed on subjects with general back pain. Future research needs to be done in this area in order to develop a more solid position on the effects their effects on facet dysfunction.
1. Facet Hypertropy -http://www.dr-bertagnoli.com/facet-hypertrophy.html
2. Facet Hypertrophy - http://www.laserspineinstitute.com/back_problems/facet_disease/facet_hypertrophy
3. Facet Joints and Low Back Pain - http://www.spineuniverse.com/conditions/back-pain/physical-therapy-relieve-back-pain
4. North American Spine Society - http://www.spine.org/Pages/Default.aspx
5. OrthoSpine and Pain - http://www.orthospineandpain.com/
6. Facet Replacement System - http://www.facetsolutions.com/AFRSproduct.html
7. Spinal Stenosis -http://www.mayoclinic.com/health/spinal-stenosis/DS00515
1. Neumann DA. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 2nd ed. St. Louis, MO: Mosby; 2010.
2. 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(5):923-944.
3. Cohen SP, Raja SN. Pathogenesis, diagnosis, and treatment of lumbar zygapophysial joint pain. Anesthesiology. 2007; 106(3): 591-614.
4. Choudhury AR, Taylor JC. Occult lumbar spinal stenosis. J Neurol Neurosurg Psychiatry. 1977; 40:506-510.
5. Barnett GH, Hardy Jr. RM. Thoracic stenosis and spondylosis. In: Tarlov EC (ed) Neurosurgical Treatment of Disorders of the Thoracic Spine. Neurosurgical topics: American Association of Neurological Surgeons Publication Committee 1991, pp. 45-51.
6. Marzluff JM, Hungerford GD, Kempe LG, et al. Thoracic myelopathy caused by osteophytes of the articular processes: thoracic spondylosis. J Neurosurg. 1979; 50:779-783.
7. Misaggi B, Gallazzi M, Colombo M. Articular facet syndrome: diagnostic grading and treatment options. Eur Spine J.2009; 18(1):S49-S51.
8. Wilde GP, Szypryt EP, Mulholland RC. Unilateral lumbar facet joint hypertrophy causing nerve root irritation. Ann R Coll Surg Engl. 1988; 70:307-310.
9. Manchikanti L, Singh V. Review of chronic low back pain of facet joint origin. Pain Physician. 2002; 5(1):83-101.
10. Gorbach C, Schmid MR, Elfering A, Hodler J, Boos N. Therapeutic efficacy of facet joint blocks. AJR. 2006; 186:1228–1233.
11. Gillet, P. The fate of the adjacent motion segments after lumbar fusion. J Spinal Disord Tech. 2003; 16(4): 338-345.
12. Katz JN, Lipson SJ, Larson MG, McInnes JM, Fossel AH, Liang MH. The outcome of decompressive laminectomy for degenerative lumbar stenosis. J Bone Joint Surg Am. 1991; 73:809-816.
13. Phillips FM, Tzermiadianos MN, Voronov LI, et al. Effect of the Total Facet Arthroplasty System after complete laminectomy-facetectomy on the biomechanics of implanted and adjacent segments. Spine. 2009; 9(1):96-102.
14. Cameron MH. Physical Agents in Rehabilitation: From Research to Practice. 3rd ed. St. Louis, MO: Elsevier, Inc., 2009.
15. Fuentes JP, Olivio SA, Magee DJ, Gross DP. Effectiveness of interferential current therapy in the management of musculoskeletal pain: a systematic review and meta-analysis. Phys Ther. 2010; 90(9):1219-38.
16. French SD, Cameron M, Walker BF, Reggars JW, Esterman AJ. A Cochran review of superficial heat or cold for low back pain. Spine. 2006; 31(9):998-1006.
17. Pieber K, Herceg M, Kienbauer M, et al. Combination treatment of physical modalities in the treatment of musculoskeletal pain syndromes: a prospective-controlled study. European Journal Translational Myology. 2010; 1(4):157-165.
18. van der Windt DA, van der Heijden GJ, van den Berg SG, ter Riet G, de Winter AF, Bouter LM. Ultrasound therapy for musculoskeletal disorders: a systematic review. Pain. 1999; 81(3): 257-71.
19. Poitras S, Brosseau L. Evidence-informed management of chronic low back pain with transcutaneous electrical nerve stimulation, interferential current, electrical muscle stimulation, ultrasound, and thermotherapy. Spine. 2008; 8:226-233.
20. Khadilkar A, Milne S, Brosseau L, Robinson V, Saginur M, Shea B, Tugwell P, Wells G. Transcutaneous electrical nerve stimulation (TENS) for chronic low-back pain. Cochrane Database Syst Rev. 2005; 3:CD003008.
21. Beurskens AJ, de Vet HC, Koke AJ, et al. Efficacy of traction for nonspecific low back pain: 12-week and 6-month results of a randomized clinical trial. Spine. 1997; 22(23): 2756-2762.
22. van der Heijden GJ, Beurskens AJ, Koes BW, Assendelft WJ, de Vet HC, Bouter LM. The efficacy of traction for back and neck pain: a systematic, blinded review of randomized clinical trial methods. Phys Ther. 1995; 75(2): 93-104.
23. Gose EE, Naguszewski WK, Naguszewki RK. Vertebral axial decompression therapy for pain associated with herniated or degenerated discs or facet syndrome: An outcome study. Neurol Res. 1998; 20: 186-190.