MSK Cortex Regional Adult Orthopaedics - Pelvis & Lower Limb

Question 1

In a low demand older patient, how long can a total hip replacement (THR) be expected to last?

Answer 1

15 years for the cup

20 years for the stem

Question 2

Why do THR loosen over time?

Answer 2

Loosening of components is predominantly due to wear particles from the bearing surface causing an inflammatory response at the implant‐bone (or cement‐bone) interface

Question 3

What are the early local complications of THR?

Answer 3

Infection
Dislocation
Nerve injury (sciatic nerve)
Leg length discrepancy

Question 4

What are the early general complications of THR?

Answer 4

Medical complications from surgery (MI, chest infection, UTI, blood loss & hypovolaemia)
Deep vein thrombosis and pulmonary embolism

Question 5

What are the late local complications of THR?

Answer 5

Early loosening, late infection (haematogenous spread from a distant site) and late dislocation (due to component wear)

Question 6

What may AVN be secondary to?

Answer 6

Alcohol abuse
Steroids
Hyperlipidaemia
Thrombophillia

Question 7

What does AVN of the hip look like on imaging?

Answer 7

Early cases may only show changes on MRI whilst later cases show patchy sclerosis of the weight bearing area of the femoral head with a lytic zone underneath formed by granulation tissue from attempted repair. The lytic zone gives rise to the classic “hanging rope sign” on x-ray

Question 8

What is the management of AVN of the hip pre-collapse?

Answer 8

Drill holes can be made up the femoral neck and into the abnormal area in the head in an attempt to relieve pressure (decompression), promote healing and prevent collapse

Question 9

What is the management of AVN of the hip if a collapse has already occurred?

Answer 9

THR

Question 10

What is the principle role of the ACL?

Answer 10

To prevent abnormal internal rotation of the tibia (although it is clinically tested by assessing anterior translation of the tibia)

Question 11

What does the PCL do?

Answer 11

Prevents hyperextension and anterior translation of the femur (although it is tested by assessing posterior translation of the tibia)

Question 12

What does the MCL do?

Answer 12

Resists valgus force

Question 13

What does the LCL do?

Answer 13

Resists varies force and abnormal external rotation

Question 14

What might clinical examination of a meniscal tear reveal?

Answer 14

Effusion
Joint line tenderness
Pain on tibial rotation localising to the affected compartment (Steinmann’s test)

Question 15

Are medial or lateral meniscal tears more common?

Answer 15

Medial (10 times more common)

Question 16

What type of meniscal tears can occur?

Answer 16

Longitudinal tears
Radial tears
Oblique tears
Horizontal tears

Question 17

Large longitudinal meniscal tears may result in what?

Answer 17

“Bucket handle tear”

Question 18

What type of meniscal tear should be considered for surgical repair?

Answer 18

Reasonably fresh longitudinal tears involving the outer 1/3 of the meniscus in a younger patient

Question 19

An LCL tear may be accompanied by an injury to which nerve and which blood vessel?

Answer 19

Common perineal nerve

Popliteal artery

Question 20

What does the extensor mechanism of the knee consist of?

Answer 20

Quadriceps muscle
Quadriceps tendon
Patella
Patellar tendon
Tibial tuberosity

Question 21

When the patella dislocates which ligament is torn?

Answer 21

Medial patellofemoral ligament

Question 22

What are the predisposing factors for patella dislocation?

Answer 22

Ligamentous laxity
Female gender
Shallow trochlear groove
Genu valgum
Femoral neck anteversion
High riding patella (patella alta)