7. Biomechanics Flashcards
1
Q
hallux interphalangeal angle:
normal range
A
normal is 0-10 degrees
2
Q
distal articular set angle (DASA):
normal range
A
normal: 7.5 degrees
3
Q
proximal articular set angle (PASA):
normal range
A
normal: 7.5 degrees
4
Q
Types of joint deformities
(hint: 3 types)
A
- Congruent – joint lines are parallel
- Deviated – joint lines intersect outside joint
- Subluxed – joint lines intersect inside joint
5
Q
3 types of bunion deformities
A
- Structural
- Positional
- Combined
6
Q
structural bunion deformities:
characteristics
A
- Bony deformity
- Abnormal PASA and DASA
- PASA + DASA = HA
7
Q
positional bunion deformities
characteristics
A
- Soft tissue deformity with subluxed or deviated joint
- Normal PASA and DASA
- PASA + DASA < HA
8
Q
combined bunion deformities:
characteristics
A
- Elements of both structural and positional with subluxed or deviated joint
- Abnormal PASA and DASA
- PASA + DASA < HA
9
Q
hallux abductus angle:
normal range
A
normal: 10-15 degrees
10
Q
true intermetatarsal (IM) angle:
normal range
A
Normal: 8-12°
11
Q
mild increase (10-13°) in IM angle:
type of procedure
A
Head procedure if mild 10-13°
12
Q
moderate increase (14-17°) in IM angle:
type of procedure
A
Shaft procedure if moderate 14-17°
13
Q
severe increase (18-21°) in IM angle:
type of procedure
A
Base procedure if severe 18-21°
14
Q
procedure for hypermobile 1st ray
A
Lapidus procedure if hypermobile 1st ray
(recall: involves fusing the joint between the first metatarsal bone and the medial cuneiform)
15
Q
metatarsus adductus angle:
normal range
A
normal: <20 degrees
(recall: bisect tarsus; distal MC, proximal MC, base of 4th Met, tip of CC joint)
16
Q
true IM angle:
calculation
A
True IM angle = (metatarsus adductus angle - 15) + IM angle
17
Q
1st Metatarsal protrusion distance:
normal range
A
Normal +/- 2 mm compared to the 2nd metatarsal
18
Q
tibial sesamoid position:
normal range
A
normal: 1-3
* (recall: tibial sesamoid in relation to line that bisects 1st metatarsal)*
19
Q
1st MPJ: normal ROM
A
- 65-75° dorsiflexion and
- 40° plantarflexion
20
Q
1st Metatarsal-medial cuneiform angle:
normal range
A
Normal: 22°
21
Q
1st ray:
normal ROM
A
- 5 mm dorsiflexion + 5 mm plantarflexion = 1 cm total ROM
22
Q
Engel’s angle:
normal range
A
Normal: <24 degrees
(recall: bisect intermediate cuneiform, bisect 2nd ray)
23
Q
Meary’s angle:
normal range
A
Normal: up to 15 degrees
(recall: angle b/w line drawn from the centers of longitudinal axes of talus and 1st metatarsal)
24
Q
1st MPJ condition:
how to determine, and the 3 types
A
- draw line parallel to articular surface of MT and base of PP
- types:
- congruous: lines are parallel and do not intersect
- deviated: lines intersect OUTSIDE joint
- subluxed: lines intersect WITHIN the joint
25
1st MPJ joint space:
normal value
2 mm width, uniform
26
1st and 2nd MT shaft comparison:
normal
should be **parallel**
*(recall: look at shaft of 1st metatarsal and compare it to shaft of 2nd metatarsal)*
27
Seiberg index:
calculation
* **distal – proximal = Seiberg's index**
* Positive with dorsal angulation → elevatus
* (recall: perpendicular distance [mm] from the dorsal aspect of the 2nd met shaft to the dorsal aspect of the 1st met.*
* *2 points = one at the neck, and the other at 1.5 cm from the 1st met base)*
28
**Fallat & Buckholz 4th IM angle**
(aka 4-5 IM angle):
normal range
* Normal: 6°
* Pathologic: 8.7°
*(recall: angle between bisection of 4th metatarsal and proximal-medial cortical border of 5th metatarsal)*
29
Fallat & Buckholz Lateral Deviation angle (lateral bowing):
normal range
* Normal 2.64°
* Pathologic \>8°
(*recall: Angle of line bisecting head and neck of 5th met and line adjacent to proximal-medial cortex)*
30
metatarsal **length**:
longest → shortest
Longest **2 \> 3 \> _5 \> 4 \> 1_** shortest
31
metatarsal **protrusion:**
longest → shortest
Longest **2 \> 3 \> _1 \> 4 \> 5_** shortest
32
**lesser MPJ** dorsiflexion/plantarflexion:
normal range
* 30-40° dorsiflexion, and
* 50-60° plantarflexion
33
metatarsal declination angle:
normal range
normal: **21 degrees**
34
\*metatarsal abductus angle:
normal range
normal: 0-15 degrees
35
IM angle of 2nd and 5th metatarsals:
normal range
normal: 14-18 degrees
36
IM angle of 1st and 2nd metatarsals:
normal range
Normal: \< 9°
Pathologic \>12°
37
IM angle of 4th and 5th metatarsals:
normal and pathologic
* Normal 4-5°
* Pathologic \>9°
*(Schoenhause says normal 4th IMA is 8°)*
38
Splayfoot angles
**1st IM angle \>12°** and **4th IM angle \>8°**
*\*With metatarsus primus adductus, there is a high predilection of splayfoot*
39
talar neck angle:
normal range at (a) birth and (b) adulthood
Long axis of head and neck with long axis of the body
* Birth: 130-140°
* Adult: 150-165°
40
talar head and neck angle:
normal
* Plantarflexed: 25-30°
* Medially aligned 15° to body
*(source:* [*https://musculoskeletalkey.com/fractures-and-fracture-dislocations-of-the-talus/#s0110)*](https://musculoskeletalkey.com/fractures-and-fracture-dislocations-of-the-talus/#s0110))
41
talar torsion angle:
normal in (a) fetus, (b) childhood, (c) adult
Head is laterally rotated on the body
* Fetus: 18-20°
* Childhood: 30°
* **Adult: 40°**
Note: this motion brings the supinated foot in utero to a more pronated adult position
42
talar declination angle:
normal, and effects of pronation and supination
Normal 21°
* **Pronation – increases** talar declination angle
* Supination – decreases
43
Meary's angle:
normal and pathologic
Intersection of longitudinal axis of talus and 1st metatarsal
* **Normal 0°**
* **Increases** with either pronation or supination
* *Pronation – moves axis of the talus plantar to 1st metatarsal*
* *Supination – moves axis of the talus dorsal to 1st metatarsal*
44
Cyma line:
define, effects of pronation and supination
S-shaped line formed by the articulation of T-N and C-C joints
* ***Pronation – moves line anteriorly***
* *Supination – moves line posteriorly*
45
talonavicular joint:
normal, effects of pronation and supination
**Normal: 75° coverage**
* **Pronation – decreases** coverage
* Supination – increases coverage
46
forefoot abductus angle:
normal
Normal 8° (0-15°)
47
calcaneal inclination angle:
normal, effects of pronation & supination
Normal 21°
* **Pronation – decreases**
* Supination – increases
48
Hibb angle (lateral view):
define, normal
Intersection of longitudinal axis of calcaneus and 1st metatarsal
* **Normal: \>150 degrees**
* Pes cavus: less than 150 degrees
used to identify the apex of deformity in patients with [**pes cavus**](https://radiopaedia.org/articles/pes-cavus?lang=us) on lateral weight bearing radiograph
49
fowler and philip angle:
define, normal, pathologic
Angle formed from the intersection of a line along the **anterior tubercle** and the **plantar tuberosity** and another line along the **posterosuperior prominence** at the Achilles tendon insertion
* Normal: \<70°
* Haglund's deformity: \>75°
50
**total angle of Ruch** (**parallel pitch lines**):
calculation, normal, abnormal
Fowler & Philip angle + calcaneal inclination angle
* Normal: 90°
* Haglunds deformity: \>90°
51
calcaneocuboid abduction angle:
normal, effect of pronation
* **Normal: 0-5°**
* **Increases with pronation**
52
**kite's angle (talocalcaneal** angle)- DP view
infant, adult, effects of pronation/supination
\*helps determine hindfoot varus or valgus
* **Infant: 30-50°**
* **Adult: 20-40°**
* Pronation – increases
* Supination – decreases
53
talocalcaneal angle - LATERAL view
normal
Normal: 25-50°
(does not change with age)
54
Subtalar joint axis direction
STJ goes through 1st ray in neutral, 2nd ray in supination, and is medial to 1st ray in pronation
55
STJ axis of motion
Lateral, posterior, plantar → medial, anterior, dorsal
* 48° from frontal plane
* 42° from transverse plane
* 16° from sagittal plane
56
STJ ROM
From neutral:
* 2/3 motion in inversion (20°) and
* 1/3 in eversion (10°)
57
longitudinal midtarsal joint ROM
* 75° from frontal plane
* 15° from transverse plane
* 9° from sagittal plane
58
oblique midtarsal joint
* 38° from frontal plane
* 52° from transverse plane
* 57° from sagittal plane
59
bohler angle:
define, normal, pathologic
Angle formed by the intersection of a line from the superior aspect of the anterior process to superior aspect of the posterior facet and another line from the superior aspect of the posterior facet to superior point of the calcaneal process
* Normal: 25-40°
* **Decreases** with intra-articular calcaneal fracture
60
gissane angle:
define, normal, pathologic
Angle formed by the intersection of a line along the posterior facet and another line along the middle and anterior facets
* Normal: is 125-140°
* **Increases** with intra-articular calcaneal fracture
61
**toygers** angle:
define, normal, pathologic
Line drawn down posterior skin surface on the radiograph where the Achilles tendon courses posteriorly as it approaches its insertion site on the calcaneus
* **Normal should be a straight line (180°)**
* **Decreases** with Achilles rupture
62
ankle dorsiflexion/plantarflexion:
normal ROM
Normal:
* 10-20° dorsiflexion and
* 20-40° plantarflexion
63
direction of ankle axis of motion
Lateral, posterior, plantar → medial, anterior, dorsal
64
tibial torsion angles:
birth, 6 years, adult
* Birth: 0°
* 6 years: 13-18°
* Adult: 18-23°
65
tibial varum/valgum:
birth, \>2 years
Compare distal 1/3 of tibia to ground
* Birth: **5-10° varum**
* \>2 years: **2-3° valgum**
66
femur angle of inclination:
1 yr, 4 yrs, Adult
* 1 year: 146°
* 4 years: 137°
* Adult: 120-136° (avg 127°)
67
femur angle of **anteversion:**
birth, adult
* Birth: 60°
* Adult: 10-12°
*(Recall: Anteversion means “leaning forward.” Femoral anteversion is a condition in which the femoral neck leans forward with respect to the rest of the femur. This causes the leg to rotate internally, so that the knee and foot twist toward the midline of the body)*
68
angle of declination:
1 yr, 10 yrs, Adult
* 1 year: 39°
* 10 years: 24°
* Adult: 6°
*(Recall: the angle formed by the femoral condyles plane (bicondylar plane) and a plane passing through the center of the neck and femoral head. It usually decreases with age)*
69
hip flexion/extension with **knee _extended_**:
normal ROM
* Normal flexion: **90-100°**
* Normal extension: **10-20°**
70
Hip flexion with **knee _flexed_**:
normal ROM
Normal flexion 120-130°
71
rotation of hip:
normal internal/external ROM
Adults: IR: 35-40, ER: 35-40
Children: IR: 20-25, ER: 45-40
72
Hip abduction/adduction:
normal ROM
* Abduction: 24-60° (avg 36°)
* Adduction: \<30°
73
Knee flexion/extension:
normal ROM
Flexion: 130-150°
Extension: 5-10°
74
knee rotation with knee flexed:
medial rotation ROM, lateral rotation ROM
* Medial rotation: 40°
* Lateral rotation: 40°
75
Knee valgum/varus (bow leg, knock knee):
76
ortolani test:
define
Test for **congenital hip dislocation/dysplasia** in newborns.
* With newborn supine and hip and **knees flexed**, the hips are **adducted** while pressing **downward** and abducted while lifting upward.
* +An unstable hip will dislocate when adducted and reduce when abducted.
77
barlow test:
define
Test for a hip that is **dislocatable but not dislocated** in infants.
* With infant supine and hip and knees flexed, **push posteriorly** in line with the shaft of femur.
* +An unstable femoral head will dislocate posteriorly from acetabulum.
78
Galeazzi (or Allis) sign:
define
Sign of unilateral congenital hip dislocation in infants.
* With infant supine and hip and knees flexed, the knees should be level.
* +If a knee is lower, that hip is dislocated.
79
Trendelenberg test:
define
Test for weak hip abductors.
* As patient stands on affected limb, pelvis drops to opposite side.
