We report on gender-specific reference intervals
of the alpha angle and its association with other qualitative cam-type
findings in femoroacetabular impingement at the hip, according to
a population-based cohort of 2038 19-year-olds, 1186 of which were
women (58%). The alpha angle was measured on standardised frog-leg
lateral and anteroposterior (AP) views using digital measurement
software, and qualitative cam-type findings were assessed subjectively
on both views by independent observers. In all, 2005 participants
(837 men, 1168 women, mean age 18.6 years (17.2 to 20.1) were included
in the analysis. For the frog-leg view, the mean alpha angle (right
hip) was 47° (26 to 79) in men and 42° (29 to 76) in women, with
97.5 percentiles of 68° and 56°, respectively. For the AP view,
the mean values were 62° (40 to 105) and 52° (36 to 103) for men
and women, respectively, with 97.5 percentiles of 93° and 94°. Associations
between higher alpha angles and all qualitative cam-type findings
were seen for both genders on both views. The reference intervals
presented for the alpha angle in this cross-sectional study are
wide, especially for the AP view, with higher mean values for men
than women on both views. Cite this article:
The reported prevalence of an asymptomatic slip
of the contralateral hip in patients operated on for unilateral slipped
capital femoral epiphysis (SCFE) is as high as 40%. Based on a population-based
cohort of 2072 healthy adolescents (58% women) we report on radiological
and clinical findings suggestive of a possible previous SCFE. Common
threshold values for Southwick’s lateral head–shaft angle (≥ 13°)
and Murray’s tilt index (≥ 1.35) were used. New reference intervals
for these measurements at skeletal maturity are also presented. At follow-up the mean age of the patients was 18.6 years (17.2
to 20.1). All answered two questionnaires, had a clinical examination
and two hip radiographs. There was an association between a high head–shaft angle and
clinical findings associated with SCFE, such as reduced internal
rotation and increased external rotation. Also, 6.6% of the cohort
had Southwick’s lateral head–shaft angle ≥ 13°, suggestive of a
possible slip. Murray’s tilt index ≥ 1.35 was demonstrated in 13.1%
of the cohort, predominantly in men, in whom this finding was associated
with other radiological findings such as pistol-grip deformity or
focal prominence of the femoral neck, but no clinical findings suggestive
of SCFE. This study indicates that 6.6% of young adults have radiological
findings consistent with a prior SCFE, which seems to be more common
than previously reported. Cite this article:
In Norway total joint replacement after hip dysplasia
is reported more commonly than in neighbouring countries, implying
a higher prevalence of the condition. We report on the prevalence
of radiological features associated with hip dysplasia in a population
of
2081 19-year-old Norwegians. The radiological measurements used
to define hip dysplasia were Wiberg’s centre-edge (CE) angle at
thresholds of <
20° and <
25°, femoral head extrusion index
<
75%, Sharp’s angle >
45°, an acetabular depth to width ratio
<
250 and the sourcil shape assessed subjectively. The whole
cohort underwent clinical examination of their range of hip movement,
body mass index (BMI), and Beighton hypermobility score, and were
asked to complete the EuroQol (EQ-5D) and Western Ontario and McMaster
Universities Osteoarthritis Index (WOMAC). The prevalence of hip
dysplasia in the cohort varied from 1.7% to 20% depending on the
radiological marker used. A Wiberg’s CE angle <
20° was seen
in 3.3% of the cohort: 4.3% in women and 2.4% in men. We found no
association between subjects with multiple radiological signs indicative
of dysplasia and BMI, Beighton score, EQ-5D or WOMAC. Although there
appears to be a high prevalence of hip dysplasia among 19-year-old
Norwegians, this is dependent on the radiological parameters applied. Cite this article:
