A total hip replacement is offered to people with severe hip pain and loss of mobility due to a degenerative condition like osteoarthritis or a serious hip fracture. It involves removing the damaged hip joint and replacing it with an artificial implant.
New research study
The link between chronic pain and cognitive decline is well-documented, although not specifically in relation to osteoarthritis. However, a research team from the University Medical Center in Hamburg recently set out to determine whether a total hip replacement for patients with osteoarthritis could have a beneficial impact on their cognitive abilities. Their findings were published in The Bone and Joint Journal (J 2022: 104-B (3): 331-340).
The link between and cognitive decline
Chronic (ongoing) pain has been linked to cognitive decline, particularly in older people with pre-existing dementia or depressive symptoms. This can manifest as memory problems, attention, decision-making, planning and flexibility. Experts are not completely sure why there is a link between chronic pain and cognitive impairment. One reason might be that pain and cognition use overlapping neural networks. Chronic pain can also cause structural, functional and chemical changes in the brain. A decrease in grey matter within the areas of the brain responsible for cognition and perception has been observed in patients with chronic pain.
The Hamburg University Medical Center has studied patients with chronic hip pain due to osteoarthritis and found a significant decrease of grey matter volume in certain areas of the brain. This normalised after the pain was eliminated following a total hip replacement, leading researchers to conclude that changes to the grey matter were the consequence rather than the cause of chronic pain.
In this latest study, they wanted to establish whether, as well as normalising grey matter and eliminating chronic pain, a total hip replacement also led to improved cognition.
Methodology
The Hamburg team studied 101 patients with severe osteoarthritis who were scheduled to undergo a total hip replacement. The average age was 67.4 and just over half (51.5%) of the patients were women. They were assessed prior to surgery and then again after three and six months. Various tests were used including the d2 Test of Attention, Trail Making Test (TMT), FAS-test, Rivermead Behavioural Memory Test (RBMT; story recall subtest) and Rey-Osterrieth Complex Figure Test (ROCF).
Findings
The team found that, after six months post-surgery, there was significant improvement in many different areas including attention, working speed and concentration, visual construction and visual memory, semantic memory, verbal episodic memory and immediate recall, as well as in pain. The team concluded that total hip replacement has a positive cognitive impact with notable improvements in attention, concentration and memory after surgery.
Neuropsychological impact of total hip replacement
As the first study to look at the impact of hip replacement surgery on cognition in patients with osteoarthritis, the results are significant and support the concept that joint replacements interact with central nervous system function. This means that the benefits of total hip replacement surgery go beyond physical function and pain reduction and may also include improving the patient’s neuropsychological prognosis. This is a new way of looking at this commonly-performed procedure and, as orthopaedic surgeons, we are excited by the implications this could have for us as a society and for our health economy.
You can find details on our website about total hip replacement, including details of our day case procedure for younger patients and those in good health.
