total hip arthroplasty

Displaced Arthroplasty

Indications

 

Patient > 70

 

Gjertsen et al JBJS Am 2010

- 4335 patients > 70 with displaced subcapital fractures

- minimum 1 year follow up

- 1 year mortality same in each group / 25%

- 22% reoperation in ORIF v 3% in hemiarthroplasty

- more pain / higher dissatisfaction / lower quality life in ORIF group

 

Options

 

Hemiarthroplasty

- unipolar monoblock

- unipolar modular

Paget's Disease

Definition

 

Chronic, non metabolic bone disorder

Characterised by increased bone resorption, bone formation and remodelling

 

Epidemiology

 

Rare < 40

1 – 3 % population over 60

M > F

 

Aetiology

 

Unknown

 

Paramyxovirus implicated

- measles

- RSV

- canine distemper virus

 

Electron Microscope

Uncemented Femur

GoalTHR Uncemented

 

Initial press fit

- implant geometry fits the cortical bone in the proximal femur

- good initial mechanical stability

 

Biological fixation for success

- good press fit

- minimal micromotion

- bony or fibrous tissue ingrowth or ongrowth

 

Templating

AimTHR Templating

 

Reproduce the normal anatomical centre of rotation

Restore femoral offset 

Maintain equal leg lengths 

 

Usually template off normal hip

 

Template

 

1. LLD

2. Offset

3. Femoral component

4. Acetabular component

5. Osteotomy / femoral seating

 

Investigation of Pain

Aetiology

 

Intrinsic

 

Infection

 

Loosening

 

Thigh pain in uncemented

- micro motion at distal end of stem

- modulus mismatch

 

Stress fracture / insufficiency fracture

- pubic rami, sacral

 

Intra-operative fracture

 

Prosthesis failure

 

Subtle instability

 

Extrinsic