The new science of hip and knee replacements

Posted on 1 July 2016

Orthopaedic surgery has come a long way. Hip or knee replacement operations are no longer a case of deep cuts, invasive surgery and long recovery times. Mediclinic Potchefstroom orthopaedic surgeon Dr Hannes Jonker talks us through the new technology in use today.

Conventional vs minimally invasive surgery
In conventional hip replacements the surgeon would make a cut along the side of your hip and move the muscles connected to the top of your thighbone to access and operate on your hip joint. The incision would usually be about 20cm long.

‘The modern technology we use for hip replacement is called minimally invasive surgery,’ explains Dr Hannes Jonker, an orthopaedic surgeon at Mediclinic Potchefstroom. ‘It’s not so invasive that we have to cut the muscles. Now we use small incisions to go in between certain muscle groups. We separate them and use that natural recess to access the joint. In the past patients had to lie on their back for a day or two after surgery. Now they’re getting up on the same day. Many of our younger, healthier patients are discharged within three days of the operation, but most older patients require a longer healing process. Even though the surgery is less invasive, it’s still major surgery!’

In minimally invasive hip replacements the surgeon will make one or two small cuts of 5-10cm, then perform the same operation through those smaller incisions. Dr Jonker says, ‘It’s less invasive, although the exposure for the surgeon is just as good as with conventional surgery.’

3D tech for knee replacements
Knee replacement surgery has also come a long way. In conventional knee replacement procedures, surgeons would use manual alignment to position the new prosthetic knee as best they could, says Dr Jonker. ‘The better you align the prosthesis, the better its survival rate,’ he says. ‘Although that’s still a subject of very wide debate.’

About five years ago, computer navigation was brought in to help the surgeon’s trained eye, but Dr Jonker points out even that type of surgery isn’t as popular any more as it used to be. ‘Today we perform a patient-specific intervention,’ he says. ‘Here we use the technology of 3D scans and 3D printers to give the patient the best possible fit – in other words, a prosthesis that is custom-fitted to their knee.’

With a tailor-made replacement, the chances of it being viable over the long term are extended even further. Dr Jonker explains the process: ‘After consultation, if required I’ll recommend a knee replacement. You’ll then go for a CT scan. From that scan we develop a web-derived 3D model, and as the surgeon I will then be able to operate on you “virtually”, positioning the prosthesis according to the best fit and the clinical notes I have of your knee. As soon as I press the button, we can start to produce the custom-made 3D model. Thereafter I can fit the prosthesis exactly as I had mapped it.’

Like the new hip replacement technology, this new approach to knee replacement promises quicker recovery, reduced risk of failure, and a better quality of life for the patient.

Published in Orthopaedics

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