Hip arthrography under general anesthesia to refine the definition of hinge abduction in Legg-Calvé-Perthes disease.
BACKGROUND
Hinge abduction is widely accepted as a poor prognostic factor in Legg-Calvé-Perthes disease (LCPD), whereas the exact definition of hinge abduction remains ill defined. The purpose of this diagnostic study was to refine the definition of hinge abduction in LCPD using conventional hip arthrography under general anesthesia.


METHODS
Among 350 hips in 332 LCPD patients, we reviewed 92 hips in 90 patients (75 boys and 15 girls) who consecutively underwent arthrography under general anesthesia because of an expected poor prognosis. The mean age at LCPD onset was 8.2 years (range, 4-13 years). With respect to lateral pillar classification, 25 hips were classified as group B, 27 as B/C border, and 40 as C. Subluxation (>or=3-mm difference from unaffected side) was present in 81 (88%) of the 92 hips. The modified Waldenström classification was used for evaluating the radiographic stage of disease at the time of arthrography: 80 hips were classified as fragmentation stage and 12 as reossification stage. Hinge abduction was defined as an increased subluxation index in maximum abduction and/or a positive impingement sign.


RESULTS
Under this definition, 11% (10 hips) of the study group had hinge abduction. The range of abduction under general anesthesia (40 degrees) was significantly greater than in the awake condition (24 degrees, P < 0.0001).


CONCLUSIONS
The subluxation index and the impingement sign proved to be reliable indicators for diagnosing hinge abduction. Conventional arthrography remains useful. General anesthesia provided an analgesic effect and muscle relaxation.


METHODS
Level II (diagnostic study, development of diagnostic criteria on the basis of consecutive patients).
Nakamura
Junichi
J
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. njonedr@yahoo.co.jp
Kamegaya
Makoto
M
Saisu
Takashi
T
Kenmoku
Tomonori
T
Takahashi
Kazuhisa
K
Harada
Yoshitada
Y
D000293:Adolescent; D017668:Age of Onset; D000768:Anesthesia, General / Q000379:methods; D001175:Arthrography / Q000379:methods*; D002648:Child; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D011379:Prognosis; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012720:Severity of Illness Index