Newer design of knee replacements not superior to older models, study finds

Older knee replacement designs are just as effective as newer models.

UK: A recent study from the Norfolk and Norwich University Hospital and the University of East Anglia determined if a newer design of total knee replacement (TKR) (Journey II BCS) gives superior patient-reported biomechanical outcomes and outcomes scores. 

Results published in the journal BMJ Open did not support the hypothesis that the Journey II BCS produces a better outcome than the Genesis II for the primary outcome of the OKS six months after surgery. The study compared the effectiveness of two established knee replacements. Iain Mcnamara, Consultant Orthopaedic Surgeon at NNUH and an honorary professor at UEA, led the research.

Eighty osteoarthritis patients received total knee replacements in 2018 and 2019 and took part in the CAPAbility study - a blinded, randomised, controlled trial run by researchers at NNUH and UEA.

Dr. Mcnamara said: “The lack of difference between implant designs is important for patients, surgeons, healthcare providers and implant companies.

“For the patient and surgeons, reassurance can be gained that older designs, with a proven track record of function and survivorship, can provide the same patient-reported and functional outcome as more modern designs."

The study is the largest published total knee replacement comparison to date, and patients will be reviewed three and five years after surgery.

Prof Mcnamara said: “For healthcare providers, older implants are often less expensive and, in the absence of clinical benefit with demonstrable longevity, the additional expenditure on more modern designs could be avoided.

“The future of design and innovation may come in the form of more modern surgical techniques such as robotic-assisted implantation to assist in placing the knee in a more kinematically sympathetic position which in turn may allow the newer design philosophies to positively influence the outcome.”

The team are planning future research looking at the effectiveness of robotic technology in knee replacement surgery. 

Reference:

McNamara I, Pomeroy V, Clark AB, et alComparison of the Journey II bicruciate stabilised (JII-BCS) and GENESIS II total knee arthroplasty for functional ability and motor impairment: the CAPAbility, blinded, randomised controlled trial BMJ Open 2023;13:e061648. doi: 10.1136/bmjopen-2022-061648