Injuries to bones and joints of the lower limb

Question 1

Pelvic fractures

Answer 1

Can result from direct trauma to the pelvic bones e.g. car accident or a fall onto the feet (forces transmitted up lower limb).

May cause injury to pelvic soft tissue, pelvic viscera, blood vessels and nerves.

Abdominal viscera can be injured, particularly the bladder (and urethra in men which sits posterior to the pubis).

Question 2

Trauma to veins

Answer 2

Causes vast blood loss because they cannot constrict.

Damage to arteries are less severe because insult causes constriction which helps reduce blood loss.

Question 3

Injury to the pelvic floor

Answer 3

Common in childbirth

Perineum, levator ani (pubococcygeus), pelvic fascia may by injured during childbirth.

Puboccygeus encircles and supports urethra, vagina and anal canal. Stretching or tearing may alter the position of the bladder and urethra.

Can cause stress incontinence, impotence in men.

Question 4

Injury to sacral plexus

Answer 4

Common during childbirth (foetal head may compress plexus)

Results in pain of the lower limb if sciatic nerve is damaged.

Obturator nerve vulnerable to injury if there is damage to the lateral pelvic wall. May cause painful spasms of adductor muscles and sensory loss in medial thigh.

Damage to plexus can also injure pudendal nerve. Can cause incontinence and impotence.

Question 5

Injury to the ilium

Answer 5

Caused by direct lateral injury e.g. trauma or falls, particularly if bones are soft or weak.

Question 6

Injury to the pubic bone

Answer 6

Disruption of the pubic symphysis caused by severe trauma to the groin.

More common in the elderly, rest and rehabilitation is the best treatment. Resolves in 6-12 weeks.

Question 7

Open book fracture of the pelvis

Answer 7

Caused by a heavy impact to the pubis (common in motorcycling accidents).

Left and right halves of the pelvis are separated at the front and rear. Requires surgical reconstruction before rehabilitation.

Increased risk of infection and haemorrhaging from vessel injury

Question 8

Pelvic ring

Answer 8

Sacroiliac joints to the pubic symphysis.

Produces stability in the pelvis.

Question 9

Acetabular fracture

Answer 9

Intra-articular fracture that damages the articular surface.

Caused by lateral blow to the greater trochanter or femur, which forces the femoral head into the acetabulum. If not repaired correctly, increases risk of arthritis

Question 10

Traumatic hip dislocation

Answer 10

Normally occurs in car accidents - hip is flexed, adducted and medially rotated when sat down. Posterior dislocations are most common.

The fibrous layer of the joint capsule ruptures inferiorly and posteriorly, allowing the femoral head to pass through the tear in the capsule and over the posterior margin of the acetabulum to the lateral surface of the ilium.

Limb appears shortened and medially rotated. Sciatic nerve may be damaged/compresed.

Must be replaced within 6hrs. Can cause chondrolysis, avascular necrosis, and lead to degenerative arthritis.

Question 11

Cruciate ligament injuries

Answer 11

ACL acts as a pivot for rotatory movements of the knee. Prevents tibia sliding posteriorly on the knee. Taut during flexion. Damaged along with MCL

PCL prevents femur sliding anteriorly on the tibia in flexion. May by injured when someone lands on a flexed knee.

Tested by drawer sign

Question 12

Compartment syndrome

Answer 12

The fascial compartments of the lower limbs are closed spaces, ending proximally and distally at the joints. Because the septa and deep fascia that form the compartments of the leg are strong, in increase in volume due to bleeding or inflammation increases intra-compartmental pressure.

Disruption to the blood supply due to fractures causes necrosis of the muscle. Infections can spread to other compartments.

Requires decompression (fasciotomy) to relieve pressure and debride and infection/necrosis.

Question 13

Fractures of the femoral neck

Answer 13

More common in women secondary to osteoporosis. Weakens the bone, resulting in a stress fracture on falling/trauma.

Can occur at several locations. Intertrochanteric line used to distinguish between intrcapsular and extracapsular fractures.

Blood supply to head of femur is unidirectional, vessels from circumflex femoral artery pass underneath the joint capsule to supply the femoral head. Fractures can disrupt blood supply and cause avascular necrosis.

Question 14

Fracture of the femoral shaft

Answer 14

The femoral shaft is large and strong, fractures occur due to violent direct injury e.g. car crash which may cause a spiral fracture.

Question 15

Appearance of a dislocated/fractured hip

Answer 15

Limb appears shorter and is laterally rotated due to the action of the muscles acting on the joint.

Gluteus maximus + deep gluteal muscles - lateral rotators

Iliopsoas and quadriceps - flex the thigh at hip

medial thigh muscles (adductors) adduct thigh at the hip

Question 16

How does compartment sydrome occur?

Answer 16

Fascial compartments of the limbs are closed spaces ending proxmally and distally at the joints.

Trauma to muscles and/or vessels in the compartment from burns, intense overuse or blunt force may produce haemorrhage, inflammation and oedema.

Because the septa and deep fascia surrounding the compartments are strong, increased volume increases intracompartmental pressure.

If the increase in compartmental pressure exceeds venous pressure, drainage stops but arterial input continues, further increasing pressure. When arterial pressure is exceeded, blood supply to the tissue stops causing ischemia and necrosis. Compression of the nerves causes pain, parasthesia and can lead to paralysis.

Question 17

Symptoms of compartment syndrome

Answer 17

Pain

Pallor

Absent Pulses

Parasthesia

Paralysis

Question 18

How would you manage compartment syndrome?

Answer 18

Fasciotomy to release compression

Question 19

Shin splints

Answer 19

Mild form of anterior compartment syndrome

Oedema and pain in the distal two thirds of the tibia. This results from repetitive microtrauma to tibialis anterior which causes small tears in the periosteum covering the shaft of the tiba and/or the deep fascia of the leg.

Question 20

SImmonds test

Answer 20

Test for tupture of the achilles tendon.

Patient lies face down with feet handing off the edge of the bed.

When the calf is squeezed if there is no movement of the foot (loss of plantarflexion) it indicates rupture.

Question 21

Potts fracture

Answer 21

Fracture-dislocation of the ankle that occurs when the foot is forcibly everted. This pulls on the strong medial ligament, and can aculse the medial malleolus.

The talus moves laterally, shearing the lateral malleolus, or can break the fibula at the tibiofibular syndesmosis. The distal end of the tibia can also be sheared off by the talus.

Question 22

Drawer test

Answer 22

Used to detect rupture of the cruciate ligaments in the knee.

Patient is supine with hips flexed to 45 degrees, knee flexed to 90 degrees.

Examiner sits on the patient’s feet and pulls the tibia forward or backwards. If the tibia pulls forward ot backwards more than normal (excessive displacement) it indicates the ACL or PCL are torn.

Must compare both sides.