Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis.
BACKGROUND
The etiology of slipped capital femoral epiphysis (SCFE) is multifactorial, but the role of sagittal balance of the pelvis as a contributing factor to its development has not been well studied. Our primary purpose was to determine whether a smaller pelvic incidence (PI), a position-independent anatomic parameter that regulates pelvic orientation, could be a factor that increases shear stress in the epiphyseal growth plate and potentially contributes to the development of SCFE. We also set out to determine whether acetabular retroversion was associated with SCFE.


METHODS
We obtained 14 cadaveric pelvi from the Hamann-Todd Osteological Collection whose femurs showed evidence of post-SCFE deformity. Two hundred age-matched, sex-matched, and race-matched pelvi were used as controls. PI and acetabular version were measured using standardized lateral photographs and goniometers, respectively. T tests were performed to evaluate for differences in measured parameters between groups.


RESULTS
The mean PI was 40.6±6.1 degrees for SCFE specimens and 47.4±9.9 degrees for normal specimens (P=0.01). The mean version of SCFE and normal acetabula was 15±7 and 17±6 degrees, respectively (P=0.39). There was also no significant difference in version between SCFE acetabula and the contralateral, uninvolved acetabular of the same specimen (15±7 vs. 17±8 degrees, P=0.33).


CONCLUSIONS
Specimens with SCFE deformity demonstrated a smaller PI than a large cohort of normal control specimens. We found no significant difference between acetabular version of specimens with and without SCFE deformity. Contralateral or unaffected acetabuli of SCFE specimens were not more retroverted than the affected side of the same specimen.


CONCLUSIONS
Sagittal balance of the pelvis, and particularly decreased PI, may play an important role in the development of SCFE. The influence of mechanical factors beyond the hip joint in the development of SCFE should be considered by clinicians.
*Department of Orthopaedic Surgery, Rainbow Babies and Children's Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH †The Warren Alpert Medical School of Brown University, Providence, RI ‡Department of Orthopaedic Surgery, Yale University School of Medicine, New Haven, CT.
Jeremy J
JJ
Gebhart
Michael S
MS
Bohl
Douglas S
DS
Weinberg
Daniel R
DR
Cooperman
Raymond W
RW
Liu
D000077:Acetabulum / Q000473:pathology / Q000503:physiopathology; D000718:Anatomy, Regional / Q000379:methods; D053587:Arthrometry, Articular / Q000379:methods; D005260:Female; D006132:Growth Plate / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000473:pathology / Q000503:physiopathology; D004856:Postural Balance; D060048:Slipped Capital Femoral Epiphyses / Q000209:etiology / Q000473:pathology / Q000503:physiopathology