Biomechanics Flashcards
Varum and valgum throughout development
Birth = genu varum (15-20 degrees) 2-4 years = straight (0 degrees) 4-6 years = genu valgum (5-15 degrees) 6-12 years = straight (0 degrees) 12-14 years = genu valgum (5-10 degrees) 14+ years = straight (0 degrees)
Ankle equinus
Less than 10 degrees dorsiflexion
Ankle joint stable position
Ankle joint is most stable in maximally dorsiflexed position
STJ axis
- 42 degrees from sagittal plane, 16 degrees from transverse plane
- Neutral position is 2/3 the distance from the most supinated position
STJ ROM
- Average ROM is 25-30 degrees (highly variable)
- Minimum of 12 degrees is required for normal ambulation
Femur ankle of inclination
Long axis of the neck vs long axis of the shaft
- Birth = 140 degrees
- Adults = 120-130 degrees
Femur ankle of declination (antetorsion)
AKA angle of femoral torsion - long axis of neck vs coronal plane of distal condyles
- 1 year = 39 degrees
- Adult = 6 degrees
Angle of anteversion
Long axis of neck of femur relative to pelvis
- Birth = 60 degrees
- Adult = 10-12 degrees
Metatarsal length
Longest - 2 - 3 - 5 - 4 - 1 Shortest
Metatarsal distal protrusion
Longest - 2 - 3 - 1 - 4 - 5 Shortest
Bohlers angle
Angle between posterior to middle facet and anterior to middle facet of calcaneus
- Normal = 20-40 degrees
- Average = 30-35 degrees
- Decreases in calcaneal fracture
Bohler’s angle bottoms out
Gissane’s angle
AKA critical angle or crucial angle - angle between middle facet to sinus tarsi and sinus tarsi to anterior facet
- Normal: 120-145
- Increases in calcaneal fracture
Gissane’s angle gets greater
Fowler-Philip angle
Angle from posterior calcaneus to plantar calcaneus
- Normal = 44-69 degrees
- Pathology = >75 degrees
Total angle
- Calcaneal inclination able + Fowler-philip angle
- Greater than 90 degrees may be observed in a Haglund’s deformity
Parallel pitch lines
- Line across plantar calcaneus
- Line perpendicular to first line
- At dorsal calcaneus, draw line perpendicular to second line (parallel to first line)
- If the posterior tubercle of the calcaneus extends above the third line there is a Haglund’s deformtiy