THR

ANZ Working Party on the Management and Prevention of Venous Thromboembolism 2007

Note

Top 6 conditions associated with DVT

- stroke

- THR

- multi trauma

- TKR

- hip fracture

- spinal cord injury

Not one of the 12 doctors was an orthopaedic surgeon

Agents

Heparin / LMWH / fondaparinux

- confirmed effectiveness

THR Complications

Early

Infection (1% risk deep infection)

Wound Haematoma

Bleeding / Transfusion

Dislocation (2 - 3% recurrent)

NVI

Fracture

DVT/PE (Fatal PE 1/1000 with chemoprophylaxis)

LLD (average 1cm, stability more important)

Medical complications

- pneumonia, UTI, CVA. IHD

Death

Late

Limp (LLD, 1 year with anterolateral approach)

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

Epidemiology

Primary THR 1%

Revision THR 3%

DDH  5%

Sciatic nerve 90% of nerve palsy

Other

- femoral nerve

- CPN

- ulna / radial nerve from positioning

Aetiology

Direct 

Laceration

- exposure / sciatic and superior gluteal nerve

- drill reamer / obturator nerve

- spike of cement / obturator nerve

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

Risk factors

Patient 

Advanced age

Immunosuppression - steroids / Rheumatoid / DM

Malnutrition - Lymphocyte count / Transferrin / Albumin

Vascular disease

Obesity

Poor skin i.e. psoriasis

Previous infection in joint

Infection elsewhere - i.e. UTi

Prolonged hospital admission

Revision surgery

Operative Factors

Preoperative

THR Acetabular Fracture

Incidence

Increased incidence with press-fit component

- especially if under ream

Prevention

Don't under-ream >1mm

In osteopenic bone 

- line to line reaming

- i.e. ream to outer diameter of cup

This also avoids leaving gaps at floor 

- very common if under-ream by 2mm

Incidence

2-3% of cases 

- doubles with infrequent operator

- second most common reason for revision after loosening

Australian Joint Registry

- dislocation accounts for 14.8% of revisions

Positions

Posterior dislocation

- hip flexed, adducted, IR