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Idiopathic Cam Morphology Is Not Caused by Subclinical Slipped Capital Femoral Epiphysis: An MRI and CT Study.

Monazzam S, Bomar JD, Pennock AT - Orthop J Sports Med (2013)

Bottom Line: The tilt angle for the CamSCFE cohort (mean, 44.5°) was found to be significantly greater than both the CamIP cohort (mean, 5.9°; P < .001) and the control cohort (mean, 12.8°; P < .001).The tilt angle for the CamIP cohort was found to be significantly less than the control cohort (P = .003).The alpha angle and tilt angle were positively correlated in the CamIP cohort, but no correlation was found in the other cohorts.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedic Surgery, Rady Children's Hospital, San Diego, California, USA.

ABSTRACT

Background: Cam impingement as a known sequelae of slipped capital femoral epiphysis (SCFE) has led to speculation that subclinical SCFEs may be the causative factor in idiopathic cam morphology; alternatively, others have implicated an abnormal extension of the growth plate as a causative factor.

Hypothesis/purpose: To investigate the growth plate tilt angle in 4 patient cohorts: normal patients, patients with idiopathic cam morphology (CamIP), patients with cam morphology secondary to known SCFE (CamSCFE), and patients with incidental findings of an asymptomatic cam (Camasymp).

Study design: Case-control study; Level of evidence, 3.

Methods: A database of 192 computed tomography scans of abdomens/pelvises of patients (ages, 5-19 years) with no known orthopaedic issues, reformatted to neutral tilt, inclination, and rotation, were utilized for the normal cohort, the Camasymp cohort, and to create an age- and sex-matched control cohort. In addition, a retrospective review of all patients treated for femoroacetabular impingement (FAI) with preoperative advance imaging was conducted, and patients were separated to CamIP and CamSCFE cohorts. The alpha angle and tilt angle were measured on each hip. Statistical analysis was performed.

Results: The mean tilt angle among the normal patients was 12.1°, with 1.9% of the variation in tilt angle being explained by age; each additional year of age decreased the tilt angle by 0.27° (P = .008). The tilt angle for the CamSCFE cohort (mean, 44.5°) was found to be significantly greater than both the CamIP cohort (mean, 5.9°; P < .001) and the control cohort (mean, 12.8°; P < .001). The tilt angle for the CamIP cohort was found to be significantly less than the control cohort (P = .003). The alpha angle and tilt angle were positively correlated in the CamIP cohort, but no correlation was found in the other cohorts. The mean tilt angle of the 18 hips in the Camasymp cohort was 13.9° ± 11.5° (range, -12° to 37°), with 12 hips (67%) in the tilt angle range of CamIP cohort and 6 in the tilt angle range of CamSCFE.

Conclusion: The proximal femoral growth plate normally has a posterior tilt that becomes more anterior through maturation. Idiopathic cam morphology has a drastically different growth plate tilt angle than cam morphology secondary to SCFE, suggesting that a majority of idiopathic cam morphology is not the result of subclinical SCFEs.

No MeSH data available.


Related in: MedlinePlus

(A) CT axial oblique image of the left hip of a 14-year-old male with asymptomatic cam morphology is shown. The tilt angle of 27° is above 2 standard deviations of the normal range, potentially demonstrating “post-slip morphology.” (B) CT axial oblique image of the left hip of a 17-year-old male with asymptomatic cam morphology is shown. The tilt angle of –12° is below 2 standard deviations of the normal range and demonstrates a more anteriorly tilted growth plate as seen in the CamIP cohort. IP, idiopathic. Image ©San Diego Pediatric Orthopedics. Reproduced with permission.
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fig5-2325967113512467: (A) CT axial oblique image of the left hip of a 14-year-old male with asymptomatic cam morphology is shown. The tilt angle of 27° is above 2 standard deviations of the normal range, potentially demonstrating “post-slip morphology.” (B) CT axial oblique image of the left hip of a 17-year-old male with asymptomatic cam morphology is shown. The tilt angle of –12° is below 2 standard deviations of the normal range and demonstrates a more anteriorly tilted growth plate as seen in the CamIP cohort. IP, idiopathic. Image ©San Diego Pediatric Orthopedics. Reproduced with permission.

Mentions: There were a total of 18 hips of the 258 (14.3%) normal asymptomatic hips ≥10 years of age with an alpha angle ≥55°. The mean tilt angle of the 18 Camasymp cohort was 13.94° ± 11.5° (range, –12° to 37°). The Camasymp cohort tilt angle was significantly greater than the CamIP cohort and significantly less than the CamSCFE cohort. Of the 18 hips, 12 (67%) were within the tilt angle range of the CamIP cohort (range, –13° to 19°) and 6 (33%) were within the tilt angle range of CamSCFE (range, 18° to 65°) (Figure 4). Additionally, 13 (72%) of the 18 Camasymp were within 2 standard deviations from the control cohort mean. Of those hips outside the normal range, 3 were above (Figure 5A) and 1 was below 2 standard deviations of the control cohort mean (Figure 5B).


Idiopathic Cam Morphology Is Not Caused by Subclinical Slipped Capital Femoral Epiphysis: An MRI and CT Study.

Monazzam S, Bomar JD, Pennock AT - Orthop J Sports Med (2013)

(A) CT axial oblique image of the left hip of a 14-year-old male with asymptomatic cam morphology is shown. The tilt angle of 27° is above 2 standard deviations of the normal range, potentially demonstrating “post-slip morphology.” (B) CT axial oblique image of the left hip of a 17-year-old male with asymptomatic cam morphology is shown. The tilt angle of –12° is below 2 standard deviations of the normal range and demonstrates a more anteriorly tilted growth plate as seen in the CamIP cohort. IP, idiopathic. Image ©San Diego Pediatric Orthopedics. Reproduced with permission.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4555520&req=5

fig5-2325967113512467: (A) CT axial oblique image of the left hip of a 14-year-old male with asymptomatic cam morphology is shown. The tilt angle of 27° is above 2 standard deviations of the normal range, potentially demonstrating “post-slip morphology.” (B) CT axial oblique image of the left hip of a 17-year-old male with asymptomatic cam morphology is shown. The tilt angle of –12° is below 2 standard deviations of the normal range and demonstrates a more anteriorly tilted growth plate as seen in the CamIP cohort. IP, idiopathic. Image ©San Diego Pediatric Orthopedics. Reproduced with permission.
Mentions: There were a total of 18 hips of the 258 (14.3%) normal asymptomatic hips ≥10 years of age with an alpha angle ≥55°. The mean tilt angle of the 18 Camasymp cohort was 13.94° ± 11.5° (range, –12° to 37°). The Camasymp cohort tilt angle was significantly greater than the CamIP cohort and significantly less than the CamSCFE cohort. Of the 18 hips, 12 (67%) were within the tilt angle range of the CamIP cohort (range, –13° to 19°) and 6 (33%) were within the tilt angle range of CamSCFE (range, 18° to 65°) (Figure 4). Additionally, 13 (72%) of the 18 Camasymp were within 2 standard deviations from the control cohort mean. Of those hips outside the normal range, 3 were above (Figure 5A) and 1 was below 2 standard deviations of the control cohort mean (Figure 5B).

Bottom Line: The tilt angle for the CamSCFE cohort (mean, 44.5°) was found to be significantly greater than both the CamIP cohort (mean, 5.9°; P < .001) and the control cohort (mean, 12.8°; P < .001).The tilt angle for the CamIP cohort was found to be significantly less than the control cohort (P = .003).The alpha angle and tilt angle were positively correlated in the CamIP cohort, but no correlation was found in the other cohorts.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedic Surgery, Rady Children's Hospital, San Diego, California, USA.

ABSTRACT

Background: Cam impingement as a known sequelae of slipped capital femoral epiphysis (SCFE) has led to speculation that subclinical SCFEs may be the causative factor in idiopathic cam morphology; alternatively, others have implicated an abnormal extension of the growth plate as a causative factor.

Hypothesis/purpose: To investigate the growth plate tilt angle in 4 patient cohorts: normal patients, patients with idiopathic cam morphology (CamIP), patients with cam morphology secondary to known SCFE (CamSCFE), and patients with incidental findings of an asymptomatic cam (Camasymp).

Study design: Case-control study; Level of evidence, 3.

Methods: A database of 192 computed tomography scans of abdomens/pelvises of patients (ages, 5-19 years) with no known orthopaedic issues, reformatted to neutral tilt, inclination, and rotation, were utilized for the normal cohort, the Camasymp cohort, and to create an age- and sex-matched control cohort. In addition, a retrospective review of all patients treated for femoroacetabular impingement (FAI) with preoperative advance imaging was conducted, and patients were separated to CamIP and CamSCFE cohorts. The alpha angle and tilt angle were measured on each hip. Statistical analysis was performed.

Results: The mean tilt angle among the normal patients was 12.1°, with 1.9% of the variation in tilt angle being explained by age; each additional year of age decreased the tilt angle by 0.27° (P = .008). The tilt angle for the CamSCFE cohort (mean, 44.5°) was found to be significantly greater than both the CamIP cohort (mean, 5.9°; P < .001) and the control cohort (mean, 12.8°; P < .001). The tilt angle for the CamIP cohort was found to be significantly less than the control cohort (P = .003). The alpha angle and tilt angle were positively correlated in the CamIP cohort, but no correlation was found in the other cohorts. The mean tilt angle of the 18 hips in the Camasymp cohort was 13.9° ± 11.5° (range, -12° to 37°), with 12 hips (67%) in the tilt angle range of CamIP cohort and 6 in the tilt angle range of CamSCFE.

Conclusion: The proximal femoral growth plate normally has a posterior tilt that becomes more anterior through maturation. Idiopathic cam morphology has a drastically different growth plate tilt angle than cam morphology secondary to SCFE, suggesting that a majority of idiopathic cam morphology is not the result of subclinical SCFEs.

No MeSH data available.


Related in: MedlinePlus