Recon Flashcards
Alpha angle on X-ray?
50-55 degrees
Centre edge angle?
Looking for acetabular dysplasia.
25 degrees
Use a cross table lateral to?
Assess a perpendicular line straight down. acetabular version should be 20 degrees, if greater too anteverted
Assess resurfacing head version. How?
Line along femur should go up 15 degrees. If more than 15 degrees too anteverted.
What type of contact is desired for metal on metal?
Polar is superior to equatorial contact
What coating is on our shells?
HA and plasma. 50 microns optimal
What is stress shielding?
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
What is the classic sign for avn of the hip on X-ray? MR?
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
Avn classification?
Ficat. Steinberg is newer classification. If there is collapse then go to Arthroplasty
Also important to determine percentage of femoral head affected.
What is the treatment for avn prior to THA?
Protected weight bearing, bisphosphonates
Core decompression, vascularised or non - vascularised bone graft
Resurfacing
THA
How much lengthening can the sciatic nerve tolerate?
3cm (some references say 4cm)
List five soft tissue changes that accompany proximal migration of the femoral head in adult DDH
Transverse orientation of abductors
Capsular thickening
Psoas tendon hypertrophy
Short hamstrings, adductors and rectus femoris
Femoral nerve exits more lateral and superior
List 4 benefits of restoring the native hip centre in DDH arthroplasty.
Lower joint reactive force
Improved abductor function
Permits limb lengthening
Better bone stock
List 3 ways to determine quality of a AP pelvis X-ray.
Coccyx in line with symphysis
Distance bw coccyx and symphysis 1-3cm (male) & 3-5cm (female)
Symmetric obturator foramina
List 4 plain radiographic indices for adult DDH and normal values.
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.
List five criteria to determine satisfactory final position of your Bernese PAO on intraop X-ray.
Horizontal roof
Congruent femoral head
Appropriate anteversion (no crossover sign)
Femoral head medialized to within 5-15mm of ilioischial line
Normal Shenton’s line
INDICATIONS FOR HIP OSTEOTOMY (list 4)
- young physiologic age (< 55 y/o)
- prearthritic / early arthrosis
- adequate hip motion
- correctable structural abnormality
CONTRAINDICATIONS TO ACETABULAR OSTEOTOMIES (list 4)
- advanced age
- moderate to severe joint arthrosis
- restricted hip ROM
- morbid obesity
ADVANTAGES OF THE BERNESE PAO (list 4)
- one incision
- perseveration of acetabular blood supply
- inherently stable → maintenance of posterior column integrity
- powerful correction → multidimensional acetabular correction (CEA correction of 20-30°)
DISADVANTAGES OF BERNESE PAO (list 4)
- anterior over-correction → acetabular retroversion (FAI)
- neurovascular injury (e.g. LCFN)
- intra-articular acetabular fracture
- technically difficult
REQUIREMENTS FOR HIP ARTHRODESIS
• 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)
High risk HO after THA
bilateral > unilateral hypertrophic OA Pagets Ank spond DISH Approach: anterior or lateral Troch osteotomy Uncemented prosthesis in the femur Prior hx of HO`
Increase risk of HO after TKA
hypertrophic OA notching femur stripping periosteum Quads muscle damage Postop hematoma Manipulation for stiffness
