Total Hip Replacement Surgery
By Dr Ooi Lai Hock

 

Introduction
Total hip replacement surgery is a reliable method of treating painful hip arthritis. The good to excellent results are as high as 95% in most long-term studies. The typical patient requiring a total hip replacement surgery is one who has failed non-surgical treatment. This group of patients have tried painkillers and physiotherapy to treat their hip pain. The use of a walking aid helps to offload the joint but the pain still persists.

Current total hip replacement surgery has changed in the past 5-10 years in terms of the surgical technique. There is renewed interest in performing surgery through smaller incisions or with muscle-sparing techniques. The reported advantage is better pain relief and rehabilitation in the post-operative period. There has also been changes to better implant designs and materials. The use of computer surgical navigation has been shown to improve alignment of the hip implant.

 

Surgical Techniques
One of the advances is that newer surgical instruments have been designed to allow for smaller incisions. These newer instruments allow the surgeon to employ muscle-sparing techniques to avoid traditional methods where muscles are cut to gain access to the hip joint. The advantage is less pain and faster rehabilitation. However, not all patients’ anatomy allow for these muscle-sparing techniques and long term results are similar to the muscle-splitting techniques.

Hip incision scar measuring 10cm

Specialised surgical instruments to allow muscle-sparing techniques or smaller incisions

 

Implant Designs and Materials
The improvement of implant design and materials allow bigger femoral heads to be used to allow for greater range of motion. The most commonly used implant articulation is the metal-on-polyethylene bearing. However, there is renewed interest in metal-on-metal and ceramic-on ceramic bearings which provide better lubrication and hence will last longer. Therefore such bearing surfaces are used in younger patients (<50 years old).1

  Metal-on-metal hip replacement with a large femoral head that allows for better range of motion and reduces the rate of dislocation


“Pink” ceramic femoral head used in this total hip replacement that has improved lubrication and longevity

 

Results and Complications:
Usually hip replacement surgery is an uneventful operation with a high success rate (98%). However, there are complications that can arise and all patients must be fully aware of the risks before surgery. The rate of complications varies from person to person. In an elderly person, the rate quoted is between 1-2%. The list of complications include:

  1. Bleeding
  2. Nerve and blood vessel injury
  3. Wound and implant infection
  4. Dislocation of the implant
  5. Fracture of bone
  6. Others: Acute myocardial infarction (heart attack), stroke, deep vein thrombosis/pulmonary embolism (clots in the veins of the leg), urinary tract infection, pneumonia.

 

References

  1. Ooi LH et al. Metal-on-metal total hip arthroplsty in young patients with a neck of femur fracture- a report of 2 cases. Presented at the 30th Annual Scientific Meeting , Singapore Orthopaedic Association, 2007.