Thigh Pain Uncemented Femur

Epidemiology

 

Ranges

- up to 4%

 

Clinical

 

Focal pain

- typically anterolateral thigh

- often tender

- corresponds to tip of stem

 

Aetiology

 

1.  Instability

 

Types

- early

- late / failed bony ingrowth

 

Cause

- micromotion at distal stem

- disadvantage of proximal coating

 

2.  Mismatch modulus of elasticity

 

A.  Component material

- mismatch between femoral component and surrounding bone

- lower with titanium stems compared with cobalt chrome stems

- titanium components less stiff & tend to have lower incidence of thigh pain

 

B.  Stem size

- more commonly seen in larger stems

- increases relative stiffness of stem compared to bone

 

3.  Stem design

- distal flutes can decrease distal stiffness

- fully porous coating decreases incidence, but increases proximal stress shielding

 

4.  Osteoporotic bone

- more commonly seen with lower bone quality

 

DDx

 

Loosening

- start up pain

 

Infection

 

Xray

 

Loosening

- migration

- progressive radiolucent lines

- abscence of spot welds

 

Bone Scan

 

No correlation of findings with thigh pain

 

Management

 

Non operative

 

Up to 2 years

- allows for remodelling

 

NSAIDS

Physio

 

Operative

 

1.  Cerclage wire cortical strut grafts

 

Theory

- improve bony rigidity over distal stem

 

Technique

- application to lateral femur

- overlap tip proximally and distally 8 cm

- must get host bone integration

- periosteal elevation / bone graft / rigid fixation

- TWB 6 weeks post op

 

Results

- good results reported

 

2.  Revision