Listening for a Hip Fracture
Abstract & Commentary
Source: Adams SL, Yarnold PR. Clinical use of the patellar-pubic percussion sign in hip trauma. Am J Emerg Med 1997;15:173-175.
Adams and yarnold offer a new bedside trick to consider in the diagnosis of hip fracture. The principle involved is osteophony, and it marks the first time I have linked the terms "orthopedic" and "stethoscope" in the same thought. The patellar-pubic percussion (PPP) sign calls for the placement of the bell of the stethoscope on the symphysis pubis while the patient is supine. Next, while the legs are in extension, each patella is percussed. Equivalent bilateral pitch and loudness is consistent with normal bony anatomy (or similar injuries bilaterally); duller percussion on one side reflects bony disruption secondary to some type of skeletal pathology, be it traumatic or atraumatic.
The authors prospectively evaluated the PPP sign in 41 consecutive patients presenting to the ED with a history of hip trauma. A pair of physicians performed the exam in a uniform manner on each patient; these examiners were blinded to historical data, recognizing, however, that some injuries were obvious by inspection alone. Only those patients whose clinicians ordered x-rays were included in the study. Plain radiography of the hip was the gold standard for fracture. If either physician noted the PPP sign to be abnormal, it was classified as abnormal for data analysis purposes.
Although these figures were not presented in the paper, the following can be calculated from the data regarding the use of the PPP sign for diagnosis of hip fracture: sensitivity, 79%; specificity, 95%; positive predictive value, 94%; and negative predictive value, 84%. Overall inter-rater reliability regarding the PPP sign was reported to be 90%.
COMMENT BY RICHARD A. HARRIGAN, MD
It is not often that you read about a new physical examination tool in the medical literature. I could find no mention of this technique in assorted emergency medicine, orthopedic, and physical diagnosis texts; this may not attest so much to the novelty of the PPP sign, but rather to its (limited) utility. Nonetheless, I found it interesting.
Since the usefulness of a physical examination finding for hip fracture would lie in its ability to let you say with certainty "if this test is negative, I don’t need to get an x-ray" (i.e., there is no fracture), the negative predictive value is important. Unfortunately, it is only 84%; therefore, the PPP sign has limited utility. Similarly, if a fracture is present, how good is the PPP sign at screening for it (sensitivity)? Once again, the results are disappointing. The specificity and positive predictive value are high, and in fact are limited by the one false-positive resultwhich occurred in a patient with Paget’s disease. As Adams and Yarnold point out, it is not surprising that osteophonic findings would be abnormal in such a case, so actually, the PPP sign is very specific (100%) for bony pathology. A test that is specific for hip fracture and bony pathology is not that useful clinically, however. I can see utility for this test in patients with other regional trauma (e.g., knee, tibia) that impairs your ability to properly examine the hip. When in doubt, however, we still need to order the x-ray.
Penicillin-Resistant S. pneumoniae in Children with Sickle Cell Disease
Abstract & Commentary
Source: Daw NC, et al. Pediatrics (electronic article) 1997;99:http://www.pediatrics.org/cgi/content/full/99/4/e7.
Pediatric hematologists from the mid-south region of the United States report on the prevalence of nasopharyngeal (NP) carriage, antimicrobial susceptibilities, and serotypes of Streptococcus pneumoniae (SP) in children with sickle cell disease. Over an 18-month period beginning in July 1994, NP cultures were obtained from 312 children, 208 (67%) of whom were receiving penicillin prophylaxis. Colonization with SP occurred in 42 children (13%), 71% of whom were receiving penicillin prophylaxis. Twenty-three of the 42 SP isolates (55%) were penicillin-resistant; 18 (78%) were of intermediate resistance, and five (22%) were highly resistant. Of the 23 isolates resistant to penicillin, 19 (83%) were obtained from children receiving penicillin prophylaxis. Penicillin-resistant SP (PRSP) organisms were also resistant to cefotaxime (43%), trimethoprim-sulfamethoxazole (57%), and erythromycin (22%). Children younger than 18 months were 2.5 times more likely to be colonized with SP than older children, and children treated with antibiotics during the preceding month were 4.6 times more likely to carry PRSP than those who were not.
n COMMENT BY LEONARD FRIEDLAND, MD
Compared with hematologically normal children, children with sickle cell disease have a 400-fold increase in SP septicemia/meningitis. The risk appears to be greatest in those children younger than 5 years old, but the disease can occur at all ages. Because of this risk in children with sickle cell disease, penicillin prophylaxis is routinely started at three months and continued until at least 5 years of age. The routine prophylactic use of penicillin has dramatically decreased the incidence of severe invasive pneumococcal infections. In the past, isolates of SP were uniformly susceptible to penicillin; however, penicillin-resistant and multidrug-resistant strains have begun to emerge in the United States and are widespread in some communities.
In this study of children followed in a Mid-South sickle cell practice, 55% of the NP SP isolates were penicillin-resistant, thus raising questions concerning the continued effectiveness of penicillin prophylaxis. Also worrisome was the high rate of resistance to cefotaxime, trimethoprim-sulfamethoxazole, and erythromycin. The results of this study serve to remind us that the initial treatment of suspected septicemia in children with sickle cell disease is no longer straightforward in the age of PRSP and multidrug-resistant SP.
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