Radiographs and Low Back Pain

(Australia—Australian Family Physician, July 1998, p. 620.) The role of radiology in the diagnosis of low back pain remains controversial. While many serious conditions may cause low back pain, their prevalence is low in primary care patients. The incidence of compression fracture is estimated to be 4.0 percent; spinal neoplasm, 0.66 percent; ankylosing spondylitis, 0.3 percent; and spinal osteomyelitis, 0.01 percent. In addition, studies have shown that many changes that may be visualized on radiography, including degenerative changes, spondylosis, osteophytes, facet joint arthrosis, subluxation and degenerative listhesis, are also present in pain-free control subjects. Radiographs also may have limited ability to detect pathology. The sensitivity and specificity of radiographs are 70 percent and 90 percent, respectively, in the detection of malignancy, 80 to 90 percent and 70 to 90 percent, respectively, in detecting osteomyelitis and 50 percent and 90 percent, respectively, in detecting spondylitis. Criteria have been suggested for the use of plain films as an aid in the diagnosis of low back pain, including history of trauma or cancer, unexplained weight loss or fever, abuse of alcohol or drugs or use of steroids, neuromotor deficit, age older than 50 years, failure to make symptomatic improvements over time, and pending legal or compensation case. The correlation of findings on radiography with clinical and historic evidence is particularly important, as is the explanation to patients and families of the potential benefits and drawbacks of using radiography in the diagnosis of back pain.

Assessment of Neonatal Jaundice

(Great Britain—The Practitioner, July 1998, p. 528.) Up to 80 percent of infants have detectable jaundice in the first few days of life, but only 5 percent have significantly elevated bilirubin levels. Most cases of jaundice are due to physiologic breakdown of hemoglobin. High levels of unconjugated bilirubin can cross the blood-brain barrier, leading to kernicterus. In the assessment of jaundiced infants, signs of sepsis, dehydration and hepatosplenomegaly are particularly important factors to consider. Causes of hemolytic jaundice must be considered. Blood type incompatibility is the most common cause of hemolytic jaundice. Children who are jaundiced 14 days after birth probably have a serious condition and should undergo blood tests for conjugated and unconjugated bilirubin, liver function tests, complete blood cell counts, thyroid function tests and urine testing for galactosemia. Jaundice associated with conjugated bilirubin may result from biliary atresia, hepatitis, infections or metabolic disorders.

Enchondroma

(Hong Kong—Hong Kong Practitioner, July 1998, p. 404.) Enchondroma is a benign cartilaginous tumor that usually occurs in the bones of the hands and the wrists. The metacarpals are most commonly affected, followed by the proximal and middle phalanges. The fifth digit is a frequent site. The lesions are often found incidentally or present as painless bony swellings. Radiographically, enchondromas appear as radiolucent lesions with well-defined sclerotic borders. Various patterns of calcification occur, including punctate, stippled or flocculent patterns. Patients occasionally have multiple enchondromas (Ollier's disease), which usually begin in childhood. Malignant transformation of enchondroma is rare.

Kienböck's Disease

(Canada—Canadian Family Physician, August 1998, p. 1616.) Avascular necrosis of the lunate was described by Kienböck in 1910 as a common cause of unilateral wrist pain of the dominant hand. The condition typically affects men who are manual laborers and are between the ages of 20 and 40 years. Although the etiology of Kienböck's disease is unknown, it is probably related to repetitive low-impact stress fractures in patients with a congenital anatomic predisposition. Many patients with this condition are believed to have only a single palmar artery supplying the lunate bone instead of the normal double arterial supply. Patients with Kienböck's disease also frequently have relatively short ulnar bones. The discrepancy between the shorter ulna and the normal length radius results in negative ulnar variance and sets up an abnormal mechanical situation that could lead to ischemia of the lunate. Patients present with localized wrist pain, reduced grip strength and limited range of motion in the wrist. Radiographs are diagnostic but may not detect early stages of the disease. Magnetic resonance imaging is the best investigation for detecting early Kienböck's disease. Initial treatment consists of immobilization of the wrist for up to 12 weeks. However, this treatment frequently fails, and the lunate collapses. Surgical interventions include radiocarpal fusion or replacement of the lunate with a prosthesis.