Microfluidic force sensor has real feel for hip replacement surgery

Implant survival rates are 89 per cent after 15 years but drop to 58 per cent after 25 years. Furthermore, hip replacement patients are often younger and more active than in previous generations, and their implants need to survive higher stresses.

The new microfluidic force sensors, developed by Professor Sohini Kar-Narayan at Cambridge University and Vikas Khanduja, a consultant orthopaedic surgeon at Addenbrooke’s Cambridge University Hospitals NHS Trust, have the potential to reduce the chances of patients needing revision surgery.

“This is a key clinical unmet need, particularly for the hip joint,” said Khanduja. “Improper implant positioning, where forces on the implant are not balanced, can lead to premature wear and necessitating complex and expensive revision procedures.”

Hip replacement surgery involves the use of a liner, which is a wear-resistant plastic component forming the bearing surface on the acetabular (cup) side of the total hip replacement.

“Integrating sensors within the trial liners during surgery will provide real-time objective feedback to facilitate soft tissue balancing and accurate implant placement, thereby potentially prolonging the longevity of the implant,” said Khanduja.

The team’s sensors, which have been awarded the 2022 Armourers and Brasiers Venture Prize, are to be commercialised via spin-out company ArtioSense Limited.

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ArtioSense’s smart sensor-embedded trial liners will aid surgeons in determining the optimum force-balanced positioning of the implant via real-time measurements. Once the optimum position is set, the surgeon removes the ArtioSense sensor-embedded liners and fits the final liner.

“This makes our technology attractive to both the surgeon, as well as the implant manufacturers, who simply need to integrate our technology into an already existing manufacturing workflow,” said Professor Kar-Narayan. “In addition, the sensors will be fabricated from inexpensive materials so will not add significantly to costs.”

She continued: “Our primary focus is on developing our smart trial liners for hip implants. However, the technology is versatile and customisable, and can be applied to similar use in other joints such as the knee, shoulders and ankles and could be adapted for use in veterinary surgery as well.”

ArtioSense will combine the £25,000 Venture Prize with its planned seed-funding round to support the development and finalisation of product specifications in advance of first in-human trials. A patent application covering ArtioSense’s microfluidic force sensing technology has been filed through Cambridge Enterprise.