Patient selection for minimally invasive spine surgery

Chapter 3: Patient selection for minimally invasive spine surgery

Jay Darji, Jason Hamamoto, Behnum Habibi


Low back pain is a common health problem suffered by millions of people worldwide and a substantial contributor to disability, affecting individual general well-being and years lived with disability (YLD). In the United States, an estimated 149 million work days are lost every year because of low back pain, with total costs estimated to be $100 to $200 billion per year (of which two-thirds is due to lost wages and lower productivity).1,2 According to a National Health and Nutrition Examination Survey (NHANES) from 2010, point prevalence for chronic low back pain was 13.1%, with the highest likelihood in the fifth and sixth decades of life.3 The proportion of people that experience low back pain during their lifetime ranges from 60% to 80%, and a report by Hurwitz et al. estimated that in 2015 roughly 500 million people globally experienced low back pain of at least 3 months duration.47

There are many risk factors that have an impact on chronic low back pain including age, gender, socioeconomic status, race, general health, occupation, and education level. Women are more likely to have chronic low back pain than men, those who are White are 1.5 times more likely than African Americans or Hispanics to have chronic low back pain, and those with chronic low back pain are less likely to have a college education.3

Compared with open spine surgery, minimally invasive spine surgery (MISS) has better cosmetic results from smaller skin incisions (sometimes as small as several millimeters). There is also less blood loss, reduced risk of muscle damage, reduced risk of infection and postoperative pain, faster recovery from surgery with less rehabilitation required, and diminished reliance on pain medications after surgery.8 In particular, transforaminal interbody lumbar fusion (TLIF) reduces the 2-year societal cost for spine surgeries, causes fewer medical complications, reduces time to return to work, and improves short-term Oswestry Disability Index (ODI) scores.8

Patient perception of MISS compared with open surgery also plays an important role in choosing treatment. The most important criteria for patients choosing between open surgery and MISS are long-term outcomes, surgeon’s recommendations, and complication risks.9 When compared with MISS, the majority of patients perceive open surgery to be more painful (83.8%), to have an increased complication risk (78.5%), to have an increased recovery time (89.3%), to have increased costs (68.1%), and to require heavier sedation (62.6%). If required to have spine surgery in the future, the majority of patients prefer a minimally invasive approach (80.0%).9


The indications for MISS are broad and include, but are not limited to:

A more detailed description of indications for MISS follows in the “Patient History” section of this chapter.


As with any medical intervention, risks must be weighed against benefits. MISS can offer select patients with alternatives to undergoing open surgical procedures. There are, however, contraindications for MISS including, but not limited to10:

Patient history

The indications for minimally invasive spinal fusion (MISF) are broad and include degenerative disease, spondylolisthesis, trauma, spinal deformities, and tumors; therefore candidates may present with a wide range of symptoms.

The patient’s history should include questions to assess the quality of the pain and its impact on the patient’s daily activities, including nighttime pain that interferes with sleep. Identifying the mechanism of injury is essential if there is an inciting event. However, symptoms may also develop insidiously. The clinician must ask the patient about any current or past treatments, bladder or bowel incontinence, saddle anesthesia, history of malignancy, inflammatory conditions, infections, history of immunosuppression, and drug use. A comprehensive review of systems may reveal red flag signs that suggest underlying infection, inflammatory disease, or malignancy, such as fever, night sweats, or unintentional weight loss.11

Patients with disc herniations are generally younger, typically 30 to 50 years old, and have a history of an acute inciting event such as lifting a heavy object, bending, or twisting motions.12 They may experience localized back pain with associated radicular pain in the arms or legs depending on the location of the herniation (cervical vs. lumbar). There may be weakness, numbness, or paresthesia in specific nerve root distributions due to mechanical and/or chemical irritation of an adjacent nerve root. Patients may also have limited trunk flexion and pain exacerbated by straining, sneezing, and coughing. Seated positioning also worsens pain because of increased pressure applied to the disc.11 It is also important to inspect the circulatory system, as vascular claudication may mimic neurogenic pathology.

Lumbar spinal stenosis is the most common indication for lumbar spine surgery in patients over 65 years old.13 Lumbar spinal stenosis classically presents as pain exacerbated by prolonged ambulation, standing upright, and low back extension, owing to the degenerated intervertebral discs, hypertrophy of the facet joints, and thickening of the ligamentum flavum protruding into the spinal canal.14 The pain is relieved by forward flexion and rest. Neurogenic claudication is an important characteristic of lumbar spinal stenosis. Symptoms are typically bilateral, but usually asymmetric involving the back, buttock, and legs. Pain in addition to numbness and tingling is present in most patients. Symptoms of numbness and tingling typically involve the entire leg and rarely affect an isolated nerve root distribution.15 Patients may report that walking upstairs is easier than downstairs, as the back is forward flexed with ascending stairs. If patients present with new-onset bowel or bladder dysfunction, bilateral lower extremity weakness, and saddle anesthesia, they may have developed cauda equina syndrome requiring emergent surgical decompression.

Patients with symptomatic spondylolisthesis may present similarly to those affected by spinal stenosis, given that symptoms arise when translation of the vertebral body compresses neural elements from canal narrowing. The clinician should pay special attention to any history of trauma when evaluating for spondylolisthesis, as pars interarticularis defects result from chronic repetitive loading in hyperextension or acute trauma. Low-grade slips and canal stenosis may decompress with forward flexion or sitting, leading to pain relief. As in spinal stenosis, pushing a grocery cart or walking upstairs results in flexion of the spinal column and thereby pain relief.16 Classically, patients complain of pain that radiates to the buttocks and both lower extremities. If the spondylolisthesis becomes unstable, as evidenced by progression on lateral flexion and extension x-rays, surgery is indicated.

The most common etiology of vertebral compression fractures is osteoporosis, and therefore it is the most common fragility fracture. Vertebral compression fractures demonstrate a bimodal age distribution, as younger patients sustain these injuries from high-energy trauma such as motor vehicle accidents or fall from height. Once the patient has been stabilized, the initial evaluation of spine fractures includes assessment of the neurologic function of the upper and lower extremities, bladder, and bowel. Many high-energy compression fractures have associated abdominal, cerebral, and extremity injuries.

There are many adults who suffer from spinal deformities, such as scoliosis, and live with significant pain and many comorbidities. Open surgical procedures to correct these deformities can be risky, sometimes requiring extensive surgical reconstruction to correct the deformity. Less invasive surgical options can help reduce the risk of complications. Mummaneni et al. previously developed a minimally invasive surgery deformity algorithm (MISDEF) for selection of patients to undergo MISS.17 These patients were selected based on sagittal parameters, and those with higher degrees of imbalance were not selected. This algorithm was revised to incorporate newer technique options, known as minimally invasive spinal deformity algorithm 2 (MISDEF2).17 In this updated algorithm, patients are grouped in classes I through IV, compared with previously being grouped in classes I to III. Patients are first grouped according to whether their deformity is fixed or flexible and subsequently on presence or absence of sagittal and coronal deformities.

Physical examination

When evaluating candidates for MISS, the physical examination should be focused yet broad enough to capture subtle findings related to spinal pathology including pain, postural changes, and gait abnormalities. The curvature of the spine should be assessed to evaluate for loss of lordosis in the cervical and lumbar region indicating degeneration. A scoliosis deformity may be observed, or the patient may have a high steppage gait to avoid toe drag owing to foot drop. Abnormal limb advancement may indicate pain in the back or extremities from nerve root compression.

The range of motion (ROM) examination of the neck and back is important to assess because loss of ROM and pain elicited in specific planes can help localize the lesion. Normal cervical spine ROM is 0 to 45 degrees of flexion and extension, 0 to 70 degrees of rotation, and 0 to 40 degrees of lateral bending.18

Lumbar spine ROM is assessed with the patient in a standing position and should be observed with the practitioner at the back or side of the patient. The practitioner may stabilize the patient by placing their hands on the pelvis to ensure that motion only occurs at the spine. Motion occurs in three planes and includes four directions, as follows: forward flexion—52 degrees ±9; extension—19 degrees ±9; lateral flexion/side bending—31 degrees ±6; rotation—32 degrees ±9.19

Palpation of the spine helps to identify focal tenderness from muscles, tendons, ligaments, and joints. The examiner should begin at the cervical region including the shoulders then work down to the lumbosacral region including the sacroiliac joints. Severe point tenderness may suggest the presence of a fracture or underlying infection such as an epidural abscess.20 It is important to note a palpable step-off deformity, which may be present in the setting of an acute trauma or severe spondylolisthesis.

Muscle strength testing is performed to evaluate for muscle weakness from a neurologic deficit, poor endurance, or muscle imbalance. Strength can be evaluated in multiple ways including manual muscle testing or functional strength testing. The most accepted method of evaluating muscle strength is the Medical Research Council Manual Muscle Testing scale that tests key muscles of the upper and lower extremities against the examiner’s resistance.21 Strength is graded on a scale of 0 to 5, and commonly tested key muscles and the corresponding spinal nerve roots include:

May 21, 2023 | Posted by in PAIN MEDICINE | Comments Off on Patient selection for minimally invasive spine surgery

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