- Author: Remi Nader, MD, CM, FRCS(C), FACS, FAANS; Chief Editor: Remi Nader, MD, CM, FRCS(C), FACS, FAANS more...
The synovial joints between the superior and inferior articular processes on adjacent vertebrae are termed the facet joints. The facet joint (also known as zygapophysial joint or Z-joint) is an important load-bearing structure in the spine. This joint plays a role in preventing extension, rotation, and anterior displacement. For more information about the relevant anatomy, see Lumbar Spine Anatomy. A remodeling process in the facet has been seen to occur in cases of damage to the joint’s bone structure and ligamentous capsule.
Images depicting facetectomy can be seen below.
Although this process can stabilize the joint, it may also lead to nerve root impingement and radiculopathy. Degeneration of the facet’s articular cartilaginous surface may cause hypertrophy of the articular surface, which can in turn lead to stenosis. It may also result in changes in the alignment and loss of mobility. As such, in addition to disk disorders, facet joint instability, degeneration, and injuries have been associated with low back pain, radiculopathy, and other spinal disorders. Osteoarthritis of the facet joint can result in synovial cyst formation and subsequent back pain unrelated to disk degeneration.
Greater shear loads in the lower spine explains why the surface areas of the lumbar facet joints increase from L-1 to S-1. Also, the facet joint angle in the coronal plane increases, from a mean of 25° at L1–2 to about 53° at L5–S1.[3, 4, 5]
Lumbar facetectomy may be performed in a partial (typically medial) or a complete way. It may also be performed unilaterally or bilaterally, depending upon the pathology and mechanism at hand. Pathologies requiring a facetectomy procedure include the following:
Degenerative spine disease (by far the most common indication; this is the focus of this paper)
Traumatic injury to the spine such as a fracture and/or subluxation requiring open reduction and fixation
Congenital conditions such as kyphoscoliosis or other states of malalignment
Neoplasms of the spine, in particular ones involving nerve roots such as schwannoma or neurofibroma
Vascular lesions of the spine extending along a nerve root sleeve such as a spinal arteriovenous malformation
Inflammatory conditions or infections of the spine leading to spinal destruction, misalignment, and requiring surgical reduction and fixation
Medial facetectomy (the most commonly performed form of this procedure) is usually performed in conjunction with a lumbar laminotomy or laminectomy and foraminotomy procedure; this is carried out with or without diskectomy. In the setting of degenerative spine disease, this operation is indicated in cases refractory to medical and conservative treatment, such as anti-inflammatory treatment, physical therapy, pain management, etc. Indications for this procedure include the following:[8, 9]
Facet hypertrophy resulting in foraminal stenosis on imaging studies (MRI or CT myelogram), and painful radiculopathy
Facet hypertrophy resulting in symptomatic central stenosis, in the setting of advanced degenerative changes
Foraminal stenosis caused by other osteophytic changes, degenerative disk disease, or herniated nucleus pulposus
Presence of a symptomatic synovial cyst
Informing the patient that the main goal of this procedure is to relieve compression at the level of the foramen and hence treat leg pain and radiculopathy is important. This procedure is not designed nor is it indicated to treat primary axial back pain.
This procedure is usually performed in the setting of a lumbar fusion, such as transforaminal or posterior lumbar interbody fusion and pedicle screw fixation. Alternatively, it may be performed unilaterally in the setting of a far lateral disk herniation (foraminal disk herniation). Removing one facet joint in its entirety does carry a more elevated risk of instability when combined with a decompressive procedure such as laminectomy (especially in extension, where alterations in rotational motion, flexibilities, and coupled motion are seen) and, while it may be performed as a stand-alone procedure, it is usually best to combine it with instrumentation and fusion.[1, 10]
When unilateral facetectomy is carried out alone, without disruption of the other posterior elements (ie, preservation of the spinous processes, interspinous and supraspinous ligaments, laminas, as well as the contralateral facet joint), the risk of instability is much lower (less than 3%).
Alternatives to medial facetectomy have been suggested, such as partial medial and lateral facetectomies with preservation of at least 50% of the facet joint, in cases of foraminal pathologies. This has been demonstrated to carry a lower risk of instability.[12, 13]
Contraindications for medial facetectomy (performed in conjunction with a lumbar laminotomy or laminectomy and foraminotomy) include the following:
Absence of neural compromise on imaging studies
Instability or deformity on imaging studies precluding further decompression without consideration for fusion
Skin or soft tissue infection at the site of the projected incision
Medical comorbidities or advanced age precluding the patient from undergoing surgical intervention
General anaesthesia with endotracheal (ET) intubation is typically used. A reinforced tube should be used because the patient is in the prone position and tube kinking is a risk to airway compromise. The ET tube should be adequately secured to the mouth with strong tape to prevent dislodgement when positioning.
In cases in which intraoperative monitoring is used, such as SSEP, EMG, or MEP, the anesthesiologist should be made aware prior to the onset of induction so as to use medications that will not affect the electrophysiological readings (eg, avoiding muscle relaxants).
Alternatively, if the patient is unable or unwilling to undergo general anaesthesia, the procedure may be performed under regional or spinal anaesthesia.
Standard surgical equipment for lumbar spine surgery is used. This includes the following:
Self-retaining or tubular retractor
High-speed drill with matchstick type bit
Nerve root retractor
Loop or microscope magnification
If a complete facetectomy is to be performed, then the use of osteotomes and a mallet should also be considered in order to remove the facet in an en bloc fashion. The complete facetectomy procedure, however, is not discussed here, as this topic's focus is primarily on medial facetectomy.
Operative adjuncts also include the following:
Preoperative studies are crucial in planning the surgical approach and determining indications. These include the following:
MRI: exiting nerve roots are visualized on the axial T2-weighted images and parasagittal T2-weighted images as well. Facet hypertrophy or synovial cyst may be evident. Gadolinium contrast can be administered in cases of reoperation to outline epidural fibrosis versus recurrent disk herniation or synovial cyst.
CT scan: used to outline bony elements, look for possible spontaneous fusion, osteophytes, calcified ligaments, pars integrity, etc. The addition of myelography contrast enables visualization of neural elements and assessment of degree of stenosis. This is especially helpful in patients unable to undergo MRI studies.
Plain x-rays with flexion/extension views (dynamic studies): enables determination of instability by subluxation and pars integrity.
The patient is positioned prone on a Wilson frame with the hips and knees flexed if a decompression procedure is to be performed, in order to straighten the lumbar lordosis, and hence open the interlaminar space.
In cases where fusion is contemplated, the back should be in the neutral position, as such, the Jackson radiolucent table is used and the patient is rotated in the prone position while maintaining neutral alignment of the lumbar spine.
In both cases, the patient’s abdomen is allowed to hang freely in order to avoid increased intra-abdominal pressure and hence reduce bleeding intraoperatively.
Preoperative antibiotics are used for infection prophylaxis and are continued for 24 hours, unless a drain is used, in which case they are continued until the drain is removed.
Deep venous thrombosis prophylaxis should be initiated intraoperatively in the form on sequential compression devices and/or ted hoses.
Intraoperative imaging is used prior to making the incision and throughout the procedure to confirm the adequate level. It is also used to guide instrumentation placement if a fusion procedure is contemplated. Care must be taken when reviewing the scans and other imaging studies to look for aberrations such as a lumbarized sacrum, bifid spinous process or other anomalies that may bring further challenges
Adequate laboratory studies should be sent preoperatively including a CBC (to rule out anemia, thrombocytopenia or elevated white blood cell count), electrolytes, coagulation profile and type and screen. Patients with a significant medical history should undergo clearance by an internal medicine specialist and preoperative optimization (eg, beta blockade in hypertensive patients, closer glucose level controls in diabetic patients).
The most common form of facetectomy procedure is discussed here, namely the medial facetectomy, performed for degenerative disk disease, which may be performed in combination with a lumbar laminotomy or laminectomy as well as foraminotomy.
Images depicting facetectomy can be seen below.
Opening and dissection
Extended midline approach
This approach is typically chosen when the pathology extends toward the midline or if signs of stenosis of the central canal exist, such as a large central disk herniation extending toward the foramen or severe degenerative changes involving facet and ligament hypertrophy.
After prepping and draping the patient in the usual sterile fashion, a needle marker is placed in the midline at the level of interest and a lateral lumbar radiograph is obtained in order to verify the adequate level.
A midline incision is then performed using a number 10 blade and is carried down through the skin and subcutaneous tissue down to the paraspinal fascia. The Cobb elevator is used to elevate the fascia on both sides, and a self-retaining retractor such as a Weitlaner retractor is then placed in order to expose the fascia.
Using the Bovie cautery the fascia is then incised in the midline down to the spinous processes of one level above and one level below the level of interest. The Cobb elevator as well as the Bovie cautery are used to dissect the paraspinal muscles that are attached to the spinous process and lamina and the dissection is extended laterally to the facet joint. This may be done unilaterally or bilaterally, depending on the pathology.
Once the facet joint is exposed, a deeper retractor such as an Oberhill or Adson-Backmann retractor or, alternatively, a self-retaining retractor such as the Versa-Trac, are then used to expose the structures of interest and retract the paraspinal muscles. At this point, a lateral lumbar radiograph is again obtained after placing a marker at the level of the lamina of interest, usually a number 4 Penfield dissector in order to verify that one is at the adequate level.
Alternatively, this approach may be performed in the minimally invasive fashion using a tubular retractor system and exposing a single lamina and facet joint level unilaterally, if addressing unilateral single level pathologies such as a lateral recess herniated disk.
Far lateral approach
The far lateral approach is typically used for paramedian pathologies that are centered around the facet joint or within the foramen such as a far lateral disk herniation. Often times, this approach may be performed in a minimally invasive fashion using tubular retractor systems.
After prepping and draping the patient in the usual sterile fashion, a needle marker is placed in the midline at the level of interest, and a lateral lumbar radiograph is obtained in order to verify the adequate level.
A paramedian incision is then performed at the level of interest that is about 2-3 cm from the midline. Depending on the retractor type used the incision is extended about 2.5 cm if the tubular retractor is to be used or 5 cm if the procedure is to be done in open fashion by using the Meyerding or Taylor retractor.
In a similar fashion as the extended midline approach, the incision is carried down with a number 10 blade through the skin and subcutaneous tissue up to the fascia. The fascia is then opened with a Bovie cautery and the underlying paraspinal muscles are identified. Finger dissection is then carried down through the plane between the longissimus and multifidus muscles; this plane is developed down to the facet joint. This plane also extends down to the dorsal ramus of the involved nerve root.
If the tubular retractor is to be used, tubes of increasing diameters are then inserted in a sequential fashion through the incision, and a tract is developed down to the facet joint. The outer tubular retractor is then inserted over the last tube and attached to an anchoring arm that is attached to the side of the table. Again the adequate level of dissection is verified using a lateral radiograph. Typically, a persistent thin layer of muscle will overlay the facet; this will have to be dissected and resected using the Bovie cautery with an extended sleeve as well as pituitary rongeurs in order to expose the bony elements of the facet joint. The lateral aspect of the laminas is also exposed, as well as the pars intra-articularis.
Bony resection and neural element decompression
A curved curette is then used to identify the plane between the 2 laminas as well as dissect any remaining soft tissue. The high-speed drill is used to drill the lateral aspect of the lamina and the medial portion of the pars interarticularis as well as the medial aspect of the facet joint down to a thin eggshell rim. Drilling is started at the level of the rostral laminae initially because the caudal laminae and facet joint are typically deep to the rostral structures. Frequent irrigation is used when drilling so as to prevent thermal injury.
Kerrison rongeurs are then used to resect the thin eggshell portion of the lamina and medial facet of the rostral level exposing the underlying caudal medial facet joint and inferior lamina. Note that when using a Kerrison rongeur, the footplate of the Kerrison must be easily slid with minimal resistance below the bony element to be resected, as any resistance encountered may be secondary to adhesions and may place the patient at higher risk of dural tear.
The ligamentum flavum or yellow ligament is then exposed and, again, using a combination of straight curettes and curve curettes, the ligament is dissected from its attachment to the underlying lamina. The ligament typically attaches to the superior medial portion of the lamina and usually the bony resection is extended to the level of the ligament attachment. It will be easier to dissect the ligaments off if the bony decompression is extended slightly more rostrally along the superior aspect of the lamina.
The caudal lamina, in a similar fashion, is also drilled down using the high-speed drill with a matchstick bur, and so is the medial aspect of the caudal facet. Note the curvature of the caudal facet along its superior aspect. The nerve root is usually impinged right below this curvature. Failure to identify this part may result in a less-than-optimal decompression. In a similar fashion, the Kerrison rongeurs are used to resect the remainder of the thin bony rim that his left from drilling.
The pars interarticularis must be identified. The medial portion of the pars may be resected; however, 1 cm of pars should be preserved in order to preserve stability, unless a fusion procedure is contemplated.
Once bony decompression is completed, then the yellow ligament can be removed. The ligament is typically preserved until as much bony decompression as possible is achieved so as to protect the underlying neural elements. Using a right-angle blunt hook, a small plane is created between the fibers of the ligaments and, subsequently, using a larger Kerrison rongeur, such as a 4-mm rongeur, the ligament is then resected. Do not pull on the ligament when resecting it; instead, bite it off with a rongeur so as not to cause any undue tension on the underlying dura. This exposes the underlying thecal sac.
Using the Woodson instrument, the neural foramen is then identified between the 2 pedicles of the vertebrae above and below. The Kerrison rongeur is then used to underbite the remaining lateral aspect facet joints and decompress the neural foramen and the nerve root in that manner. Adequacy of the decompression is verified again by passing the Woodson instrument, which should easily pass with no resistance through that foramen. In a similar fashion, the neural foramen of the level below is also identified distal to the caudal pedicle, and a foraminotomy can be performed at that level if indicated.
When addressing herniated disk pathology, the thecal sac is then retracted medially using a nerve root retractor and the underlying herniated or bulging disk is exposed. A small needle marker is placed in the disk to verify exact location, and a lateral lumbar radiograph is obtained prior to performing the annulotomy. This typically exposes also epidural veins and some epidural bleeding will occur at that site. The bipolar cautery at a low setting is then used to coagulate any bleeding. The use of Gelfoam powder with thrombin or FloSeal is also recommended to aid in hemostasis prior to start of the diskectomy.
The diskectomy is then carried in the usual fashion. When dealing with cases of disk extrusion, the disk extruded fragment should be immediately visualized once retracting the thecal sac and may be then resected using pituitary rongeurs. In cases of contained disk herniations, an annulotomy is performed using a number 15 blade, and the cuts through the annulus fibrosis are typically performed parallel to the thecal sac so as to avoid thecal sac injury by inadvertent extension of the cuts.
Subsequently, the pituitary rongeur is used to resect the bulging portion of the disk. The remainder of the disk may then be also resected in a piecemeal fashion using straight curettes to dissect the remainder of the nucleus pulposus from within the interbody space and using reverse angled (Epstein) as well as angled curettes to remove the disk portions that are more medial and lateral. Subsequently pituitary rongeurs that are straight, up-angled, and down-angled are used to resect as much disk is possible from within the disk space. Finally, the curettes are then used to verify that no free fragments of nucleus pulposus (which may herniate at a later time) remain within the disk. The disk space is then irrigated with antibiotic impregnated saline solution. This is done by using a small red rubber catheter so as to prevent future diskitis or infection.
In cases in which a lumbar fusion is contemplated, such as in cases of primarily axial back pain or axial back pain that is significant in combination with radicular symptoms, then the facet joint may be resected in its entirety and all bony elements resected are typically preserved and cut down to smaller pieces to be later used as locally harvested bone graft. The details of lumbar fusion and instrumentation are beyond the scope of this paper.
Prior to achieving closure, adequate hemostasis should be completed after profuse irrigation with antibiotic impregnated saline solution of the incision. Hemostasis is achieved in the usual fashion using the bipolar cautery to cauterize any bleeding vessels. The bipolar cautery should be set at a low setting when close to the thecal sac or neural elements so as not to cause any thermal injury to the surrounding nerves. Gelfoam powder with thrombin or FloSeal are then used to further achieve hemostasis and aid in control of venous oozing. Irrigation is then completed again.
Closure is then done in layers starting with the paraspinal muscles and fascia, which are closed using 0-Vicryl interrupted sutures. The subcutaneous tissues are closed using 2-0 or 3-0 Vicryl interrupted buried sutures. The skin may be closed with staples or subcuticular 3-0 Monocryl suture. A Blake or Jackson-Pratt drain may be left in place along the bony elements and tunneled subcutaneously to a distal exiting site if any oozing of blood during closure remains.
Adequate dressings are applied and the patient is then turned back to the supine position and extubated.
Disk replacement with preservation of motion has been used to address lower back pain of discogenic origin. Facet replacement has been used lately to address instability created by the surgical decompression or to address chronic instability or replace painful facet joints.
Postoperative considerations are as follows:
The patient is mobilized 6 hours after the procedure.
Adequate analgesia is given, such as patient controlled analgesia (PCA pump) or intravenous narcotics. Typically, patients who are on chronic pain medications are restarted on their preoperative medications and may have added breakthrough intravenous analgesics.
The patient may be kept on antibiotics for 24 hrs.
If stable and ambulatory, the patient may be discharged in 24 hrs.
See the list below:
Extensive manipulation of the nerve root should be avoided, as it may cause persistent pain postoperatively.
Dural tears should be treated under the microscope. The tear should be exposed in its entirety by removing more bone. It is then sutured with 5-0 Prolene. Fibrin glue is then placed along the dural surface.
Wound infection is prevented with antibiotic prophylaxis. Postoperatively, the wound is kept clean and the dressing changed every day.
Spinal instability can be caused by excessive drilling and removal or wider portions of the facet or the pars interarticularis.
CSF leakage from the wound can be treated with wound reinforcement and lumbar drain placement.
Epidural or subcutaneous hematoma may need reoperation.
Disk reherniation or herniation of residual fragment may need reoperation.
Injury to the thecal sac or cauda equina can occur.
Neuropathic or complex regional pain syndrome may be a source of persistent pain.
Positioning injuries should be prevented (eg, brachial plexus, ulnar nerve injuries).
After multilevel procedures for removal of tumors, long-term instability or deformity may occur. 
See the list below:
Return to work status is evaluated after 1-2 months.
The patient is followed for at least 3 months postoperatively via monthly visits.
An LSO corset can be given to the patient to wear during the recovery on an intermittent basis.
In cases of lumbar fusion, serial radiographs are obtained on a monthly basis to assess adequacy of the instrumentation in bony bridge formation. 
In cases of workers compensation, maximal medical improvement can be evaluated after 3 months and may require the performance of a functional capacity evaluation by a trained physical therapist prior to return to work
See the list below:
Patients are instructed not to lift any heavy objects with the typical weight restriction of about 10-20 pounds. [23, 24]
Patients are also instructed to avoid sitting or standing for prolonged period of time greater than 20 minutes and also avoid riding in a motorized vehicle for more than 20 minutes at a time without frequent breaks in which the patient will get out of the vehicle and stretch.
During the healing process, typically, some axial muscular back pain exists; however, the radicular symptoms should improve. Improvement may be seen immediately postoperatively or may take several days to weeks to occur, especially in cases in which some neuropathic-type damage or chronic changes within the nerve root or dorsal root ganglion occurred.
Patients should also be instructed that, given the fact that they have undergone a decompression, they will have some limitations for the rest of their lives with regards to any type of strenuous activity. They should be very careful with their use of their lower back. Patients should be referred to a physical therapist, occupational therapist are other allied health or posture specialists (such as an Alexander technique specialist  ) to assist them with training for adequate use of their lower back.
As a general rule, in all cases of degenerative spine disease, the patient should be instructed to stop smoking if a smoker or lose weight if overweight.
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