Clinical Practice Guideline
Developed for the
Aerospace Medical Association
by their constituent organization
Overview: Chronic recurrent low back pain is commonly defined as pain that has persisted for three months that has not responded to conservative management or, alternatively, three distinct episodes in one year, each lasting at least six weeks, that has recurred despite conservative management.2, 3, 5, 10, 13, 16
Approximately 75-80% of adults will suffer from low back pain at some point in their life and it is second only to upper respiratory problems as a reason to visit their primary care physician.2, 8, 11, Low back pain affects men and women equally in the age range of 30 to 50 years and it is the most common cause of work related disability in people under 45 years of age.15 Fitzgerald and Crotty found a 13% incidence of backache directly related to flying in Royal Air Force pilots.22
The risk factors include heavy lifting, bending, twisting, vibration, excessive weight, poor conditioning, static work postures, sustained or repeated applications of force, sustained awkward postures, rapid repeated motions, cold environment, fatigue, smoking, and psychological/psychosocial factors.2, 8, 12, 14, 16 Vibration is not routinely thought of, but it was the most commonly reported cause of back pain or disorder in occupations that had prolonged whole body vibration exposures.17 Vibration exposure in the 4 to 6 Hz range, as seen in motor vehicle operation (truck drivers), has been shown to be a risk factor for low back pain.2, 9, 16 In the aeromedical environment, rotary wing aviators are at the highest risk for vibration associated injury. Repeated exposures to vibration can fatigue the paraspinal musculature which can lead to injury.17, 22
One study reported that 90% of patients with low back pain seen within three days of the injury or onset of pain completely recovered within two weeks using conservative therapy.7 In another study, up to 40% experienced a recurrence of their back pain within six months.4 If low back pain is still present at six months, the likelihood of an individual ever resuming normal activities is 40 to 55% and almost 0% at two years.16
Mechanical low back pain accounts for 97% of the diagnosis; 70% due to lumbar strain/sprain, 10% due to degenerative processes, 4% due to herniated disc, 4% due to osteoporotic compression fracture, 3% due to spinal stenosis, 2% due to spondylolisthesis, less than 1% due to traumatic fracture, and less than 1% due to congenital disease. Referred pain from visceral disease accounts for 2% including disease of the pelvic organs, renal disease, aortic aneurysm, and gastrointestinal disease. Non-mechanical spinal conditions account for approximately 1%; includes neoplasia (0.7%), inflammatory arthritis (0.3%), and infection (0.01%).8 This clinical practice guide primarily deals with mechanical low back pain due to lumbar strain/sprain and degenerative processes. See the Herniated Nucleus Pulposus and Spinal Fusion, Spinal Fractures, and Spondylolisthesis waiver guides for those topics.
Aeromedical Concerns: The final aeromedical disposition for mechanical low back pain due to lumbar strain/sprain and degenerative processes is dependent on the degree of functional residual impairment that remains once treatment and rehabilitation are completed. The flight surgeon must ascertain that the airman can safely perform all flight duties. There should be no significant limitation of motion, loss of strength, or functional impairment that may compromise safe operation of the aircraft, and/or safe egress. If the patient responds well to therapy and there are few or no recurrences, the airman may be eligible for continuation of flight duties. If the low back pain is recurrent and disabling it is disqualifying for all flight classes regardless of the cause. Low back pain due to other causes such as herniated disc, spondylolisthesis, and spinal fractures has unique aeromedical concerns and is discussed in their respective waiver guides.
Aircrew members who wear chest, back or seat style parachutes may use a lumbar pad to provide comfort to the lumbar region of the individual’s back and keep the spine in the best position to withstand shock. Life support can obtain, fit and provide specific guidance on the use of lumbar pad.
Medical Work-up: Initial evaluation of low back pain should include a history and physical to help place the individual with low back pain into one of three broad categories: nonspecific low back pain, back pain potentially associated with radiculopathy or spinal stenosis, or back pain potentially associated with another specific spinal cause.6 The “red flags” of back pain in the history must be addressed (more likely to be in the latter two categories); history of trauma, age greater than 50 years or less than 20 years, history of malignancy or immune compromised, pain which worsens when supine, recent onset of bowel or bladder dysfunction, saddle anesthesia and severe or progressive neurologic deficit of the lower extremities.9 Other significant history includes; chronic corticosteroid use, unexplained weight loss, IV drug use, recent urinary tract infection, pain over one month duration, or failure to improve with conservative therapy.9, 16 Psychosocial factors and emotional distress should be assessed because they are stronger predictors of adverse low back pain outcomes than either physical examination findings or severity and duration of pain. Routine imaging and other diagnostic tests in individuals with nonspecific low back pain is not recommended, whereas in individuals with low back pain and severe or progressive neurologic deficits are present or when serious underlying conditions are suspected then imaging is appropriate.6 Individuals with persistent (> 4 weeks) low back pain and signs or symptoms of radiculopathy or spinal stenosis should be evaluated with MRI and plain radiographs. Of note, anatomic evidence of a herniated disc may be found in 22 - 40% of asymptomatic persons. Bulging discs may be seen in up to 81% of asymptomatic persons.8 Electromyography /nerve conduction velocity may help in the diagnosis of nerve route irritation and can confirm clinical findings of abnormal motor or sensory function.1
Multiple therapeutic modalities are available for mechanical back pain, particularly lumbar strain/sprain and degenerative processes. For acute back pain (< 4 weeks), these include initial short-term bed rest (less than 2 days), walking and normal daily activities as quickly as possible, short-term opioid analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, benzodiazepines, and manipulation. For chronic back pain, NSAIDS and acetaminophen, exercise and physical therapy, back school, massage, yoga, acupuncture, spinal manipulation, cognitive-behavioral therapy and/or progressive relaxation can be effective.6 Meta-analyses have concluded that acupuncture is significantly more effective than sham therapies for the short-term relief of chronic low back pain, although not superior to other active therapies.13 Spinal manipulation may be mildly effective for some individuals with chronic low back pain. Traction, corsets and braces have not been shown to be of much benefit for acute or chronic back pain or prevention of recurrence of back injury. When appropriate, weight reduction, posture and body mechanics training “back school” and strengthening and flexibility programs should be instituted.1, 13 Tricyclic antidepressants have been shown to effectively treat chronic pain8 (although not waiverable for aircrew). One study showed that medium-firm mattresses improved pain compared to firm or hard bed mattresses.13 With chronic low back pain, an early multidisciplinary approach to combine cognitive-behavioral therapy, patient education, supervised exercise, selective nerve blocks, or other strategies to restore functioning is recommended.1, 8
Aeromedical Disposition (military): Air Force: Chronic low back pain is disqualifying for FC I/IA, II and III. Waiver may be granted in trained FC II and III aviators when the diagnosis is clearly delineated and the pain is controlled either with conservative, non-pharmacological means or using therapeutic doses of ibuprofen, naproxen, acetaminophen or aspirin.18
The aeromedical summary should include:
A) History - Must define the back pain symptomatology; location, radiation, duration, conditions that improve or aggravate the pain, limitations of activities, treatment, and medications. Address pertinent negatives.
B) Physical exam – range of motion, muscle strength, gait, sensation, reflexes, etc.
C) Reports of any radiological or neurological studies and lab work to exclude specific causes of back pain.
D) All specialty consults/opinions obtained.
Navy: Waiver may be recommended when the pain is controlled by conservative, non-pharmacological means, and is not associated with an organic cause. Designated personnel with osteoarthritis requiring low dose NSAIDs who can maintain close supervision by a flight surgeon may be considered for a waiver on a case by case basis.21
Army: Waiver may be granted when the pain or discomfort is controlled by conservative, non-pharmacological means or with the chronic use of NSAIDs. 19
Aeromedical Disposition (civilian): Low back pain from any etiology is considered under the category of “general medical condition”. This states that “No other organic, functional, or structural disease, defect, or limitation that the Federal Air Surgeon, based on the case history and appropriate, qualified medical judgment relating to the condition involved finds - (1) Makes the person unable to safely perform the duties or exercise the privileges of the airman certificate applied for or held; or (2) May reasonably be expected, for the maximum duration of the airman medical certificate applied for or held, to make the person unable to perform those duties or exercise those privileges. No medication or other treatment that the Federal Air Surgeon, based on the case history and appropriate, qualified medical judgment relating to the medication or other treatment involved, finds - (1) Makes the person unable to safely perform the duties or exercise the privileges of the airman certificate applied for or held; or (2) May reasonably be expected, for the maximum duration of the airman medical certificate applied for or held, to make the person unable to perform those duties or exercise those privileges”. Chronic low back pain if it is symptomatic or requires medication, other than nonsteroidal anti-inflammatory agents, is disqualifying unless the applicant holds a letter from the FAA specifically authorizing the Examiner to issue the certificate when the applicant is found otherwise qualified. As in most conditions, the FAA considers each case on its own merit. Any type of “chronic pain syndrome” that requires even intermittent analgesics will likely be unacceptable. If the applicant presents evidence documenting that the underlying condition for which the medicine is being taken is not in itself disabling and the applicant has been on therapy (NSAID) long enough to have established that the medication is well tolerated and has not produced adverse side effects, the Examiner may issue a certificate.20
Waiver Experience (military): Review of large military electronic waiver database from 2001 through mid-August 2007 showed 93 entries for lumbago ICD-9 (724.2). Of the 93 waiver entries, 38 (41%) were disqualified. Of the 38 disqualified personal, 14 (37%) had multiple diagnoses and an additional 7 (18%) were disqualified due to medications.
Waiver Experience (civilian): The current pathology coding system does not permit specific numbers of cases to be determined.
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