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Study looks at Total Hip Replacement vs Partial Hip Replacement for fractures of neck of femur

Earlier this year a 107 year old woman had a partial hip replacement (a 'hemiarthroplasty') and became the oldest patient in Australia to have this operation(1). In her case it was an emergency procedure after a fall resulting in a fracture to the neck of her femur on her right side. The ball joint was replaced by a prosthetic ball and metal stem.

Although acknowledged to be a high risk procedure, without it the patient would have been bedridden for the rest of her life. Fractured neck of femur is a relatively common injury presentation to hospitals in elderly individuals, and it is a serious one almost always requiring surgery.

Hip replacement for this injury is technically similar to hip replacement for arthritis, but this is where the similarity ends. Although she holds the age record for hip surgery, the average age for patients undergoing hip replacement in Australia is 82, and around 22,000 hip replacements are carried out every year.

There are many factors to consider (age of course is one of them) when making recommendations to patients with fractured neck of femur for hip replacement. Although there are different surgical approaches with each procedure, hip replacement can either be total (Total Hip Replacement or 'THR') or partial, (called a hemiarthroplasty). As the name implies, THR involves replacing the entire natural ball and socket joint at the hip with prosthetic components, whereas a hemiarthroplasty involves replacing only the femoral head, ie. the ball joint at the end of the femur.

A recent study led by a research team based at McMaster University in the United States(2) looked at outcomes after hip replacement surgery with a group of 1,495 patients aged 50 or older in ten countries, where surgery was required after a displaced femoral neck fracture. All of the patients in the study had been able to walk prior to the injury. One group of patients underwent total hip replacement surgery and the other group hemiarthroplasty.

The study found that the type of surgery had no significant influence on either the need for revision surgery in the 24 months after the initial procedure, or on the death rate in the same period. Serious complications arose in 42% of patients who underwent total hip replacement surgery and in 37% of those undergoing a hemiarthroplasty.

Patients undergoing THR experienced less pain and stiffness and better function than those who had a hemiarthroplasty, but the team concluded that this difference was not statistically significant.

Current medical thinking is that, where the acetabulum is not unduly affected by arthritis, a hemiarthroplasty is suitable for older patients who are not very physically active, as it is a shorter procedure and there may be a lower chance of dislocation compared to THR.

THR on the other hand is considered more suitable either where significant arthritis is affecting the acetabulum or where the patient is either younger or more physically active or both.

The current study is reassuring that hemiarthroplasty is a reliable and valid option that can be considered even in not-so-elderly patients with fractured neck of femur, should it be preferred or recommended by the clinician based on individual patient condition.

(1) Daphne Keith is the oldest Australian to get a partial hip replacement
(2) Total Hip Arthroplasty or Hemiarthroplasty for Hip Fracture The New England Journal of Medicine 26 September 2019