disadvantages

Results 

90% fusion rates

Lose70% sagittal plane ROM

Disadvantages of Arthrodesis 

Non union rates up to 12%

Decreased gait speed

Poor mobility over uneven surfaces

Philosophy

Need the least amount of constraint necessary to obtain sufficient stability

Increasing constraint

Advantages

- increase stability

Disadvantage

- increase stress at implant host interface

3 Types

1.  Unconstrained

A.  Posterior cruciate retaining

Options

1. Always resurface

2. Never resurface

3. Selectively resurface

Decision Making

Controversial

- literature divided on issue

Historically

- poor outcomes due to poor implant design

- now improved designs

- non resurfacing also improved due to better design and improved techniques in regard to tracking and rotation

Aim

UKA is intended to be load sharing

- correct to neutral or slight varus

HTO is a load-shifting / load-sparing procedure

- over correct into valgus

UKA v TKR

Advantages UKA

1.  Rapid rehabilation

Definition

The perpendicular distance from the centre of the femoral head to the long axis of the femur

Harris 1992

- aim for supra-physiologic offset 

- avoid making offset less than original at all costs & makes longer if possible

Soft tissue balancing equals restoring femoral offset

Effect of short offset

1.  Abductor lurch / Trendelenburg gait

Concept

Femur

- removal of femoral head cartilage

- resurfacing with metal

- cemented / uncemented

Acetabulum

- standard technique

Bearing surface

- metal on metal

Indications

Relatively young man (40 - 50)

OA

Indications

Young adult 

- 16 - 30 years old

- monoarticular disease

- heavy demand 

Exhausted options of osteotomy

- risk of THA failure  / multiple revision surgeries considered too high

Aims of arthrodesis

Maximise bony contact

Minimise shortening