Identifying under-reported instances of peri-prosthetic fracture

Peri-prosthetic femoral fracture is a sudden and devastating complication of hip and knee replacement surgery. In a high proportion of cases these injuries require further surgery which can be associated with significant morbidity and risks for patients. This study funded by Orthopaedic Research UK (ORUK) is looking at a specific cause of failure of hip and knee replacements – peri-prosthetic fracture, where the femur supporting the hip replacement or the knee replacement breaks. When this occurs it is instantly debilitating; patients are normally admitted to hospital as an emergency and almost always need an operation. They are typically old and frail, so the recuperation and rehabilitation are lengthy; they are typically in hospital for 5 to 7 days before surgery and they are then inpatients in for at least a month before they return home.

The bulk of research in the UK to date has been based upon either small case-series or on a subset of patients treated with only revision surgery captured within the National Joint Registry (NJR). According to one of the project’s lead researchers, Jonathan Evans.

‘The NJR is an amazing resource, but it only captures those incidents where a break is treated with a replacement. What it’s not capturing is where the bone is fixed around the original hip or knee replacement. We believe that this has led to the under-reporting of peri-prosthetic fractures.’

This research project gives a more complete picture of the incidence and outcomes of periprosthetic femoral fractures in England including how many patients die after this surgery, how long they remain in hospital and the costs associated with treatment of these injuries. It combines data from the NJR with the Hospital Episode Statistics (HES) database to give a more complete picture of what is happening. It reveals that around 50% of fractures, which did not result in revision surgery, have been excluded from the NJR data. Jonathan Evans says,

‘When you include all the peri-prosthetic fractures that are treated with fixing rather than revision, it goes from the third biggest reason for failure to by far the biggest. Over half of these injuries are treated without changing the implant. It is a much more common injury than we thought and means that researchers have been inadvertently ignoring a significant number of cases. Having identified the true scale of the problem, we can encourage much more investment in research, and on prevention and treatment.’

The findings of this research project will be used alongside data from the National Hip Fracture Database to raise awareness of the previously unidentified incidence of the injury and the potential impact on patients. This will help patients by giving more detailed information to aid the consent process for total hip and knee replacement surgery, as well as supporting patients and health care professionals in the treatment of these injuries. The researchers plan to undertake a series of interviews with patients and carers to better understand their needs and expectations. Jonathan Evans says,

‘Ultimately what we want is to design interventions to improve care for these patients. We need to answer questions such as ‘Are we fixing them in a particular way? Does it matter how we fix them? Does it matter how soon we get them up on their feet? Do we need to have specialist rehabilitation programmes, and do we need to have support for the families? We are also working with health economists to analyse potential cost savings for the NHS.’

This project has already raised awareness and led to the formation of two national working groups within the British Association of Surgery to the Knee and the British Hip Society. These working groups are using the results of this research project to create plans for the care of patients and future research into periprosthetic fractures.

The research funded by ORUK has been undertaken in parallel with another project funded by the University of Leeds which is investigating whether there is a link between instances of fracture and the type of hip replacement used. The Leeds study is being led by Dr Josh Lamb, an honorary clinical fellow at the University of Leeds, who Jonathan Evans credits with grappling with the ‘hard statistics’ and finding linkages in the datasets that had eluded other researchers.

The researchers would like to acknowledge the work and support of Professor Michael Whitehouse, Dr Adrian Sayers and the rest of the team at the Musculoskeletal Research Unit at the University of Bristol. The National Joint Registry, in particular, the patients, staff and research sub-committee without whom this project would not be possible.