Biomechanics Flashcards
When is the hip at most risk in DDH?
12th week gestation - if LE rotates medially, will develop atypically
18th week gestation - hip muscles developing; arhtrogryposis or spina bifida can lead to dislocation
36-40 weeks gestation - mechanical forces associated with breech presentation can lead to dislocation
Contributing factors to DDH in late gestation
Breech presentation- Hip flexion with knee extension
First-born children
Large babies
Limited uterine space
Associated conditions with DDH
Congenital muscular torticollis
Metatarsus adductus
Oligohydramnios
How can DDH be spotted on ultrasound?
Femoral head is totally uncovered by ilium- at least 1/2 should be covered
What is Galeazzi sign?
Hooklying, feet flat, asis level
Observe for 1 knee higher than the other, screening for leg length discrepancy and hip joint integrity
Clinical presentation of DDH (3 mo. to 1 yr)
Limited hip ABD during diaper changes
Leg-length discrepancy
Clicking with hip movement
Uneven leg folds at gluteal line
Clinical presentation of DDH (>1 yr)
Pelvic obliquities
Lumbar lordosis in response to hip contracture due to bilat. dislocations in children that are walking
Trendelenburg gait
Treatment for DDH
Pavlik harness
Hip abd splint
6-12 wks; 23/24 hrs/day or more
Hip spica cast
Most reliable way to measure leg length
ASIS to medial malleolus with tape measure
Normal femoral neck/shaft angle
120-135 degrees
Surgical treatment for femoral varus
Wedge osteotomy
Legg–Calvé-Perthes disease
A condition affecting blood supply to femoral head, causing bone to collapse
How to measure knee varus/valgus?
Distance between medial malleoli or between patella in standing or supine
Intervention for knee varus/valgus
Epiphysiodesis
8 plate
Stapling
Normal femoral version
12 degrees relative to frontal plane
Femoral anteversion
INCREASE in femoral head/neck angle relative to frontal plane
Instability
Femoral retroversion
DECREASE in femoral head/neck angle relative to frontal plane
Impingement
Normal femoral torsion
12 degrees relative to the femoral condyles
Femoral retrotorsion
Decreased angle between femoral head/neck relative to femoral condyles
Externally rotated thigh
Femoral antetorsion
Increased angle between femoral head/neck relative to femoral condyles
Internally rotated thigh
T/F: Tibial torsion is present at birth
False
Develops with weight bearing
18-23 degrees as an adult
How is tibial torsion measured?
Thigh-foot angle
Transmalleolar angle test to eliminate forefoot deformities
