templating

1.  Templating

Xray

AP in plane of scapula

- template glenoid 

- most inferior screw is in thick bone of scapular axillary border

AP humerus

- size and fit of diaphyseal and metaphyseal humeral components

CT

Aim

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

Issues

Templating

Approach

Fixation

Bearing Surface

Head Size

Offset

Indications

Disabling hip pain

Severe functional impairment

Failed non operative management

Not Indicated 

Painless deformity

Issue

Most common reason for litigation against orthopaedic surgeons in THR

Usually from lengthening

Complications of LLD

1.  Nerve palsy

Sciatic nerve - tolerate average 4.4cm lengthening

Common peroneal nerve - tolerate average 2.7 cm lengthening

Lengthen by up to 15-20% of the resting nerve length

- but in reality is unknown and multifactorial