lower limb- bones

Question 1

describe bony features of the ilium (8 points)

Answer 1

• body joins ischium and pubis to form acetabulum
• has “wing like” alae (for fleshy attachment of muscles) , extending out to iliac crests
• on the iliac crests are the anterior superior iliac spine (ASIS)- quite palpable-, anterior inferior iliac spine (AIIS), posterior superior iliac spine (PSIS) and posterior inferior iliac spine (PIIS)
• 5-6cm posterior to the ASIS is the iliac tubercle
• below the PIIS is the greater sciatic notch- the inferior border of which is the ischial spine (actually part of the ischium
• the lateral surface of the ilium has 3 gluteal lies which are the attachments of gluteal muscles
• medially each ala has a smooth depression, the iliac fossa
• posteromedially the illium articulates with the sacrum via the rough auricular surface and iliac tuberosity superior to it

Question 2

describe bony features of the ischium (5 points)

Answer 2

• forms posteroinferior part of hip bone, body of ischium fuses with pubis and ilium to form the acetabulum
• ramus of ischium joins inferior ramus of pubis to form ischiopubic ramus, making the inferior border of the obturator foramen.
• posteriorly the ischial spine is the inferior border of greater sciatic notch.
• below the ischial spine is the smaller, rounder lesser sciatic notch
• below the lesser sciatic notch is the ischial tuberosity- the part that you sit on. also provides tendinous attachment for the posterior thigh muscles.

Question 3

describe bony features of pubis (4 points)

Answer 3

• anteromedial part of hip bone, anterior part of acetabulum, proximal attachment for muscles of medial thigh. has a body and two rami
• medially the symphysis of body of pubis articulates with the contralateral pubis (pubic symphysis)
• antero-superior part of the united bodies is the pubic crest (wh/ provides attachment for abdominal muscles). at either end of this crest are the pubic tubercles wh/ are important inguinal landmarks
• the inferior ramus articulates with the ischium, the superior ramus articulates as part of the acetabulum

Question 4

describe the obturator foramen (2 points)

Answer 4

• aperture in the hip bone bounded by pubis, ischium and their rami
• closed by a thin, strong obturator membrane with a small canal (obturator canal) wh/ allows passage of obturator nerve and vessels.

Question 5

describe the acetabulum (simple bony markings) (3 points)

Answer 5

• large cup shaped cavity on lateral hip bone that articulates with the head of femur
• margin is incomplete inferiorly at the ace tabular notch
• rough depression in the floor of the acetabulum is the ace tabular fossa

Question 6

where are the common sites of avulsion fracture of the hip bone? (1 point)

Answer 6

• at the sites of muscle attachment eg. ASIS, AIIS, ischial tuberosities, ischiopubic rami.

Question 7

describe the angles found in the proximal femur (2 points)

Answer 7

• angle of inclination: angle between the long axis of the head/neck and the shaft. approx 115-140 degrees (av 126). greatest at birth and diminishes with age. less in females.
• angle of torsion/angle of declination: angle between horizontal axis of head/neck and horizontal axis of femur. about 12 degrees.

Question 8

describe bony features of the proximal femur (5 points)

Answer 8

• where the neck joins the shaft are the greater and lesser trochanters.
• lesser trochanter extends medially from the posteromedial part and gives attachment to illiopsoas
• greater trochanter is large and laterally placed, projects superiorly and posteriorly. provides attachment for abductors and rotators.
• intertrochanteric line joins trochanters anteriorly. formed by attachment of iliofemoral ligament.
• intertrochanteric crest joins the trochanters posteriorly

Question 9

describe the bony features of the shaft of femur (4 points)

Answer 9

• slightly convex anteriorly
• the line aspera runs on the posterior surface providing attachment for adductors of thigh. in the medial third, this line has medial and lateral lips.
• superiorly the lateral lip of the line aspera blends with the gluteal tuberosity, the medial lip blends with the spiral line
• interiorly the lies aspera divides into the medial ad lateral supraepicondylar lines which lead to the spirally curved medial and lateral condyles.

Question 10

describe the bony features of the distal femur (4 points)

Answer 10

• essentially consists of medial and lateral femoral condyles. these articulate with menisci and tibial condyles to form the knee joint.
• the menisci and tibia condyles glide across the poster-inferior aspect of the femoral condyles during flexion and extension
• the condyles are separated posteriorly and inferiorly by an intercondylar fossa but merge anteriorly forming a shallow depression- the patella surface
• lateral and medial epicondyles provide sites for muscular attachment. superior to the medial epicondyle is the adductor tubercle which also provides attachment

Question 11

what is coxa vara? how about coxa valga? (2 points)

Answer 11

• coxa vara is when the angle of inclination is decreased

- coxa valga is when the angle of inclination is increased

Question 12

what is a slipped epiphysis? (1 point)

Answer 12

• occurs in older children or adolescents. epiphysis of femoral head may slip away from femoral neck causing progressive coxa vara. can be due to acute trauma or repetitive micro trauma.

Question 13

what are the common types of femoral fractures? (2 points)

Answer 13

• NOF is most commonly fractured, esp secondary to osteoporosis- this includes transcervical, intertrochanteric, subcapital. impaction often occurs.
• fracture of greater trochanter, shaft or spiral fracture usually only occurs in major trauma/direct trauma/sports. fractures of the distal femur may separate the condyles and subsequently disrupt neuromuscular structures.

Question 14

describe bony features of the proximal tibia. (5 points)

Answer 14

• superior end is widened to form medial and lateral condyles which provide a flat surface called the tibial plate.
• the tibial plateu is actually 2 articular surfaces. the medial one slightly concave, the lateral slightly convex. these articulate with the condyles of the femur.
• the two articular surfaces are separated by the intercondylar eminence, made up of medial and lateral intercondylar tubercles. this fits into the intercondylar fossa.
• the anterolateral aspect of the condyles bears the anterolateral tibial tubercle which provides attachment for the ITB
• the lateral condyle also has a fibular articular facet.

Question 15

describe bony features of shaft of tibia. (3 points)

Answer 15

• is somewhat triangular- its three sides are the medial, lateral/interosseous, posterior
• at the superior end of the anterior border, the tibial tuberosity provides attachment for the patella ligament
• the shaft is at its thinnest at the junction of its middle and distal thirds.

Question 16

describe bony features of the distal tibia. (3 points)

Answer 16

• the distal end of the tibia flares only medially to form the medial malleolus.
• the inferior surface of the shaft and lateral surface of the malleolus articulate with the talus.
• the interosseous border of the tibia is sharp where it gives attachment to the interosseous membrane of the two leg bones. inferiorly this sharp border is replaced by the fibular notch.

Question 17

describe bony features of the fibula. (4 points)

Answer 17

• lies posterolateral to the tibia and is attached to it by the tibiofibular syndesmosis which includes the interosseous membrane.
• no function in weight bearing, serves mainly for muscle attachment.
• distal end enlarges and is prolonged laterally as the lateral malleolus, more prominent and posterior than the medial malleolus.
• like the tibia, the fibula is triangular in cross section

Question 18

what types of tibial and fibular fractures can occur? (5 points)

Answer 18

• compound fracture can result from direct trauma.
• transverse stress (march) fractures can occur in the inferior 1/3 when non conditioned people take long hikes.
• torsional injuries can cause diagonal fracture of the shaft at the junction of middle and inferior thirds as well as assoc fibular fracture.
• disruption of the epiphysial plate at the tibial tuberosity can result in recurring pain and osgood schlatter disease (in adolescence)
• fibular fractures commonly occur in assoc with fracture dislocation of the ankle joint

Question 19

name the bones of the foot (1 point)

Answer 19

• seven tarsal bones (talus, calcaneus, cuboid, navicular and three cuneiforms), 5 metatarsal bones, 14 phalanges

Question 20

describe the arrangement of the tarsal bones. (7 points)

Answer 20

• the superior (trochlear of) talus articulates with the mortise of the ankle.
• the talus then transmits the weight of the body onto both the calcaneus and the forefoot. it does this by sitting on top of the calcaneus but also by resting its head on an “osseoligamentus shelf/hammock” which is suspended between a medial ridge of the calcaneus (the talar shelf) and the navicular bone.
• the calcaneus makes up the heel of the foot. its anterior 2/3 supports the talus and it also has a medial projection, the talar shelf. its weight bearing prominence is the calcaneal tuberosity.
• the navicular articulates with the head of talus (the bit on the “hammock” posteriorly and with the three cuneiforms anteriorly.
• the cuboid sits infero-lateral to the navicular
• the three cuneiforms articulate with the navicular posteriorly and the lateral one articulates with the cuboid laterally
• beyond this is the metatarsus

Question 21

describe some important fractures of the foot bones

Answer 21

• calcaneal fractures can occur after a hard fall onto the heel. often comminuted. very disabling b/c it disrupts the subtler joint.
• fractures of the talar neck may occur during severe dorsiflexion e.g.. brake pedal injury in MVA
• metatarsal fractures can occur when a heavy object falls on the foot. also common in dancers when dancing demi-point. fatigue fracture of the metatarsals can occur with prolonged walking.
• sudden and violent inversion of the foot can result in avulsion of the 5th metatarsal