Week 23: MSK Part 2/2: Rhabdo, Back Pain, & more

Sacroiliitis is an inflammatory disorder of the sacroiliac joint in the posterior pelvis. It is a feature of spondyloarthropathies such as ankylosing spondylitis. Patients may present with low back pain or pain in the buttock or leg. There is tenderness to palpation of the sacroiliac joint but no pelvic instability. Patients with ankylosing spondylitis are usually men less than 40 years of age and often report back pain and stiffness that is worse upon waking up and improves with activity throughout the day. Plain films of the spine may demonstrate “squaring” of the vertebral bodies (bamboo spine). Referral to a rheumatologist and treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) are recommended. Emergent causes of low back pain (e.g., spinal cord compression, spine infection, trauma) should be considered and screened with directed history and physical examination. Concerning features of back pain include history of trauma, recent surgery, intravenous drug use, old age, history of cancer, fever, focal neurologic deficits (e.g., weakness, numbness), urinary or bowel dysfunction, and unexplained weight loss. Patients with these features should be worked up for emergent causes of back pain such as malignancy, cord compression, or infection with advanced imaging, blood cultures, and potentially consultation to a spine surgeon.

Central cord syndrome (A) is the most common spinal cord syndrome and presents with upper extremity weakness greater than lower extremity weakness. It is caused by extreme neck extension. Pott’s disease (B) is vertebral osteomyelitis. Patients usually present with fever and other signs of infection such as tachycardia, leukocytosis, and erythema overlying the area of infection. A psoas abscess (C) is an infected fluid collection of the iliopsoas muscle compartment. Patients are usually ill-appearing and septic with fever and back pain, flank pain, or lower abdominal pain that does not improve throughout the day.

Fluoroquinolone drugs, including levofloxacin, have been associated with spontaneous tendon ruptures. Fluroquinolones are a commonly prescribed antibiotic class. The class includes ciprofloxacin, moxifloxacin and levofloxacin. The fluoroquinolone class of drugs has a number of side effects, the most serious of which are prolongation of the QTc and spontaneous tendon rupture. Tendon rupture appears to be more common in older patients. The overall risk is between 0.1 – 0.4%. These drugs are discouraged for use in pregnant women and children secondary to their effect on cartilage.

Sciatica is a lumbosacral radiculopathy that is caused by compression of the spinal nerve root(s). 90% of all cases are due to disc herniation, although spinal stenosis, spondylolisthesis, and piriformis syndrome are other notable causes. Symptoms typically develop suddenly during physical activity and consist of back pain radiating down the leg, though the pain may radiate bilaterally. Weakness and numbness in the affected limb may also be present. The straight leg raise (SLR) is a good screening test for sciatica with 92% sensitivity and 28% specificity. The patient’s affected leg is extended and passively elevated. Pain elicited in a sciatic nerve distribution past the knee indicates a positive test. Pain elicited in the back alone is not considered positive. The crossed straight leg raise compliments the straight leg raise well in that it has a sensitivity of 28% and specificity of 90%. The crossed straight leg raise is performed by passively elevating the extended unaffected leg. A positive test is signified by pain evoked in a sciatic nerve distribution in the affected leg. Atraumatic sciatica does not necessitate imaging. Imaging should be sought when there is concern for infection or malignancy or when significant neurologic deficits are present (e.g., marked weakness, numbness, or bowel/bladder dysfunction). MRI is the preferred imaging modality in these cases. Treatment of sciatica is largely symptomatic with the use of non-narcotic analgesics, preferably nonsteroidal anti-inflammatory drugs, and activity as tolerated. Steroids and neuropathic pain medications have not shown significant efficacy in sciatica. With conservative management, most patients’ symptoms resolve after six weeks. Surgical treatment via discectomy is reserved for patients who have failed conservative management. However, while studies have shown short-term improvement in pain control after surgery, no difference in long-term pain control has been found between conservatively and surgically managed patients.

Crossed leg raise alone (A) has good specificity, but poor sensitivity. Crossed straight leg raise and straight leg raise (B) should be used together, however the straight leg test has the highest sensitivity and the crossed straight leg raise has the highest specificity. Straight leg raise alone (C) has good sensitivity, but poor specificity.

This young patient with low back pain and morning stiffness that improves with exercise most likely has ankylosing spondylitis. Ankylosing spondylitis is an inflammatory arthritis that primarily affects the spine and is associated with human leukocyte antigen (HLA-B27). Diagnosis is made using a combination of clinical symptoms, lab testing, and radiographic findings suggestive of sacroiliac joint pathology. Classically, X-ray imaging shows fusion of vertebrae (“bamboo spine”) as the peripheral fibers of the intervertebral annulus fibrosus discs ossify. However, symptoms can be present up to 10 years before radiographic evidence of the disease is apparent. Patients generally present with arthritic symptoms most apparent in the lower back, but can also have enthesopathy (as in this patient’s Achilles tendon pain), uveitis, and fibrosis of the upper lobes of the lung. The sacroiliac joint can be tested by flexing, abducting, and externally rotating one leg (FABER test). If pain is elicited on the posterior, contralateral side, it is suggestive of sacroiliac joint pathology. If pain is elicited on the anterior, ipsilateral side, it is suggestive of pathology within the hip. The mainstay of treatment is nonsteroidal anti-inflammatory drugs (NSAIDs) along with tumor necrosis factor antagonist medications.

Osteoarthritis (B) can also cause back pain, but generally affects older patients and usually improves with rest rather than worsening. The sacroiliac joints are rarely affected. Rheumatoid arthritis (D) can cause arthritic pain in younger individuals with morning stiffness, but usually affects small joints (hands, feet, and cervical spine). Osteofibrous dysplasia (C) is a fibrovascular defect of the long bones that leads to replacement of cortical bone with fibrous tissue. The disease is usually painless and spinal involvement is extremely rare.

Rhabdomyolysis is the result of the breakdown of skeletal muscle releasing the intracellular contents into the bloodstream. In minor cases, patients are asymptomatic but with severe cases the condition is life threatening with severe electrolyte disturbance and renal failure. The ultimate final pathway in rhabdomyolysis is the accumulation of intracellular cytoplasmic calcium which leads to myocyte destruction. This occurs as a result of direct cell membrane damage and ATP depletion. The hallmark of diagnosis is the presence of elevated serum creatine kinase and myoglobinuria. Management of rhabdomyolysis involves treating or removing the underlying cause, correcting electrolyte abnormalities and prevention of renal failure. Intravenous fluid administration is the mainstay of therapy titrating to a goal urine output of 3 mL/kg/hr.

Standard therapy used to include alkalinization of both serum and urine with the administration of sodium bicarbonate. An alkaline pH of the urine (A) above pH of 6.5 is the goal in alkalinization. This is not achieved with intravenous normal saline as described in the vignette. Intravenous fluid should be continued until clearance of the plasma creatine kinase. Precise guidelines do not exist, but the goal CK should be a level less than 1000 U/L, not 15,000 U/L (B). A creatinine less than 1.0 mg/dL (C) is not a standard goal of hydration for rhabdomyolysis. If renal failure is present, hydration will continue until improvement although no specific value is identified as the target.

The subacromial space is an area between the coracoacromial arch and the greater tuberosity of the humerus. It contains the long head of the biceps tendon, the supraspinatus tendon, and the subacromial bursa. Subacromial bursitis is most often an overuse injury due to chronic impingement. Patients who participate in frequent overhead activity are most at risk. The most common complaints are pain with overhead movement and difficulty finding a comfortable position at night due to pain. On physical examination, they likely will have a positive Neer impingement sign (pain with arm in 180 degrees forward flexion, followed by internal rotation) and Hawkins impingement sign (pain with arm in 90 degrees abduction, elbow flexed at 90 degrees, followed by internal rotation). Initial treatment is conservative with rest, nonsteroidal anti-inflammatory drugs and activity modification. Some patients may need additional physical therapy or a subacromial bursa steroid injection. Those with continued pain may proceed to further imaging with ultrasound or MRI and consideration of decompression surgery with orthopedics.

Acromioclavicular separation (A) involves partial or complete tearing of the acromioclavicular and coracoclavicular ligaments. It follows an injury to the shoulder, most often a direct or blunt hit to the shoulder. On examination, there is often a notable deformity at the AC joint along with associated tenderness to palpation. Adhesive capsulitis (B) or “frozen shoulder” is an inflammatory reaction within the capsule and synovium of the glenohumeral joint. It results in significant global loss of active and passive range of motion of the shoulder (forward flexion, abduction, external rotation and internal rotation). It can occur following an injury or spontaneously in those with autoimmune disorders such as diabetes or hypothyroidism. Full-thickness supraspinatus tear (C) most often occurs following an acute injury and presents with an inability to abduct the arm and a positive empty can test (unable to hold arm in 90 degrees of abduction with internal rotation).

auda equina syndrome results from compression of the conus medullaris and nerve roots, most commonly fromherniated discs, bone fragments, hematomas, epidural abscess, tumors, or vascular insufficiency. The compression classically occurs below L1. Patients present with complaints of low back pain, lower extremity pain, paralysis or paresthesia, saddle anesthesia, impotence, and bowel or bladder dysfunction. Urinary retention is the most consistent finding with a sensitivity of 90%. A thorough history about recent spinal procedures, trauma, anticoagulation, intravenous drug use, and malignancy help aide in determining the cause. On physical examination, lower extremity deficits, whether sensory or motor, may be present. Frequently asymmetric and unilateral signs and symptoms are present. Absent or decreased rectal tone and bulbocavernosus reflexes and a palpable bladder due to urinary retention may also be present. Patients with a suspicious history and physical concerning for cauda equina require emergent MRI imaging for evaluation. CT myelogram may be utilized in patients unable to have an MRI performed. Treatment consists on surgical decompression by a spine surgeon.

Fecal incontinence (A), motor deficits (B), and saddle parenthesis (C) all may or may not be present in a patient with cauda equina syndrome, but none of these symptoms are the most sensitive.

Rhabdomyolysis is the breakdown of striated muscle resulting in release of intracellular contents into the extracellular fluid and circulation. This can result in a spectrum of disease severity ranging from asymptomatic elevation of muscle enzymes to life-threatening electrolyte imbalances, acute renal failure, multiorgan failure, and death. There are several causes of rhabdomyolysis such as exertion, drugs and toxins, trauma, infections, electrical current, hypoxia, hyperthermia, or metabolic disorders. However, in the United States, it occurs most often due to prolonged muscle compression in the intoxicated patient who lays motionless or in the elderly with dementia following a fall. Patients classically present with complaints of muscle weakness, myalgias, and tea-colored urine. Physical examination may reveal muscle weakness, tenderness and swelling, or skin color changes, such as blistering or discoloration. Compartment syndrome should be considered if the exam reveals a firm compartment, pain on passive extension, and neurovascular compromise. The diagnosis of rhabdomyolysis can be made with a creatine kinase level greater than five times normal. Other laboratory abnormalities may include an elevated serum myoglobin, myoglobinuria, large blood on urinalysis with the absence of red blood cells, hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, and hypoalbuminemia. The mainstay of treatment is with high volumes of normal saline to maintain a urine output of 200 to 300 mL/hr. Urine alkalinization theoretically enhances renal myoglobin clearance and can be achieved by adding bicarbonate to the intravenous fluids to maintain a urine pH greater than 6.5. This can be used as an adjunct, however, there are potential adverse effects such as hypernatremia, fluid overload, and exacerbation of hypocalcemia.

Elevated creatinine (B) may be seen in rhabdomyolysis that is complicated by acute renal failure, however, it is not diagnostic. Hypokalemia (C) is not diagnostic of rhabdomyolysis. Potassium levels are typically elevated in rhabdomyolysis. Large blood on urinalysis with red blood cells present (D) is not diagnostic of rhabdomyolysis, however, large blood on urinalysis with the absence of red blood cells is diagnostic of rhabdomyolysis and is due to myoglobinuria.

Pain with passive stretch of the effected compartment is the most common symptom early in compartment syndrome. Compartment syndrome develops when pressure builds within a confined anatomical space. Increasing pressure leads to decreased perfusion compromising tissue. Tissue ischemia eventually leads to death of muscle, nerve and bone tissue. Although it is typically associated with major trauma and crush injuries, it can develop after a relatively minor injury. Any compartment that is prescribed by fascial planes can develop compartment syndrome. However, the lower extremities are the most common location due to their higher risk for injury and their relatively low-volume compartments. Long-bone fractures account for 75% of all traumatic compartment syndromes. Patients will present with pain that is often out of proportion to examination.

Although pallor (B), parasthesias (C), pulse deficit (D) and paralysis are four of the classic symptoms, pain with passive stretch of the muscles involved is the most common early finding. Early recognition is key as prompt decompression can be limb saving.

Grade IA recommendation is for early activity and to avoid bed rest (by RCT).

The first choice for patients with mild to moderate back pain should be acetaminophen or a nonsteroidal anti-inflammatory drug (NSAID) like ibuprofen or naprosyn. In patients with severe pain, opiate medications may be necessary. However, it is important to note that no studies have demonstrated the superiority of one pain medication (or class of medication) over another in the treatment of back pain. Patients with milder symptoms should initially be treated with acetaminophen or an NSAID. These medications are well tolerated in short courses with minor side effects. NSAIDs have not been shown to be superior to acetaminophen.