Recon

Question 1

Alpha angle on X-ray?

Answer 1

50-55 degrees

Question 2

Centre edge angle?

Answer 2

Looking for acetabular dysplasia.

25 degrees

Question 3

Use a cross table lateral to?

Answer 3

Assess a perpendicular line straight down. acetabular version should be 20 degrees, if greater too anteverted

Question 4

Assess resurfacing head version. How?

Answer 4

Line along femur should go up 15 degrees. If more than 15 degrees too anteverted.

Question 5

What type of contact is desired for metal on metal?

Answer 5

Polar is superior to equatorial contact

Question 6

What coating is on our shells?

Answer 6

HA and plasma. 50 microns optimal

Question 7

What is stress shielding?

Answer 7

Component takes the force, surrounding bone becomes osteopenic, due to wolffs law, which suggest tissue react to forces applied.

Extensive coating increased prox stress shield

Question 8

What is the classic sign for avn of the hip on X-ray? MR?

Answer 8

Crescent sign. The femoral head density does not change but you can get surrounding disuse osteopenia

MRI you get single line sign on T1, double line sign on T2

Question 9

Avn classification?

Answer 9

Ficat. Steinberg is newer classification. If there is collapse then go to Arthroplasty

Also important to determine percentage of femoral head affected.

Question 10

What is the treatment for avn prior to THA?

Answer 10

Protected weight bearing, bisphosphonates

Core decompression, vascularised or non - vascularised bone graft

Resurfacing

THA

Question 11

How much lengthening can the sciatic nerve tolerate?

Answer 11

3cm (some references say 4cm)

Question 12

List five soft tissue changes that accompany proximal migration of the femoral head in adult DDH

Answer 12

Transverse orientation of abductors
Capsular thickening
Psoas tendon hypertrophy
Short hamstrings, adductors and rectus femoris
Femoral nerve exits more lateral and superior

Question 13

List 4 benefits of restoring the native hip centre in DDH arthroplasty.

Answer 13

Lower joint reactive force
Improved abductor function
Permits limb lengthening
Better bone stock

Question 14

List 3 ways to determine quality of a AP pelvis X-ray.

Answer 14

Coccyx in line with symphysis
Distance bw coccyx and symphysis 1-3cm (male) & 3-5cm (female)
Symmetric obturator foramina

Question 15

List 4 plain radiographic indices for adult DDH and normal values.

Answer 15

Lateral CE angle normal 25-39
Anterior CE angle normal 25-50
Tonnis angle normal <10
Adult Acetabular angle (of Sharp) normal is 33-38.

Question 16

List five criteria to determine satisfactory final position of your Bernese PAO on intraop X-ray.

Answer 16

Horizontal roof
Congruent femoral head
Appropriate anteversion (no crossover sign)
Femoral head medialized to within 5-15mm of ilioischial line
Normal Shenton’s line

Question 17

INDICATIONS FOR HIP OSTEOTOMY (list 4)

Answer 17

• young physiologic age (< 55 y/o)
• prearthritic / early arthrosis
• adequate hip motion
• correctable structural abnormality

Question 18

CONTRAINDICATIONS TO ACETABULAR OSTEOTOMIES (list 4)

Answer 18

• advanced age
• moderate to severe joint arthrosis
• restricted hip ROM
• morbid obesity

Question 19

ADVANTAGES OF THE BERNESE PAO (list 4)

Answer 19

• one incision
• perseveration of acetabular blood supply
• inherently stable → maintenance of posterior column integrity
• powerful correction → multidimensional acetabular correction (CEA correction of 20-30°)

Question 20

DISADVANTAGES OF BERNESE PAO (list 4)

Answer 20

• anterior over-correction → acetabular retroversion (FAI)
• neurovascular injury (e.g. LCFN)
• intra-articular acetabular fracture
• technically difficult

Question 21

REQUIREMENTS FOR HIP ARTHRODESIS

Answer 21

• younger age (< 30)
• high activity level
• failure of non-operative mgnt
-severe pain / stiffness
-post-traumatic arthrosis / end stage disease associated w/ previous infection
• normal neighbouring joints (lumbar spine, contralateral hip, ipsilateral knee)

Question 22

High risk HO after THA

Answer 22

bilateral > unilateral hypertrophic OA
Pagets
Ank spond
DISH
Approach: anterior or lateral
Troch osteotomy
Uncemented prosthesis in the femur
Prior hx of HO`

Question 23

Increase risk of HO after TKA

Answer 23

hypertrophic OA
notching femur
stripping periosteum
Quads muscle damage
Postop hematoma
Manipulation for stiffness