HipLink: Registry-Retrieval Linkage

What problem did we seek to address?

There is now a wealth of information available to patients on joint replacements. One of the biggest sources is the National Joint Registry (NJR) for England, Wales and Northern Ireland, who have collected data on more than 1.8 million operations (1). They now publish on their website how different implants, surgeons and hospitals are performing. The purpose of our study was to answer the simple question: ‘How accurate are NJR reports?’

How did we tackle the problem?

HipLink

First, we made sure there were no mistakes in our data. We took implants at the LIRC out of storage and re-analysed them to make sure that their details were correct. We then joined the two big databases at the LIRC and the NJR and used a process called ‘validation’ to check for errors.

What were the main findings?

We found that, where a procedure was reported to the NJR, they did an excellent job of recording it. Data completion was over 99.9% for all fields and the error rate was typically less than 5%. We also showed that NJR data was getting better, year-on-year. However, we found that a sizable number of procedures were missing from the NJR database and we could only identify 60.9% of the implants we held at the LIRC.

What does this mean for patients?

This study has shown that the NJR database is largely well completed and accurate. It is probably the best source of data we currently have to analyse how joint replacements perform.

Across the Registry as a whole, missing data probably ‘averages itself out’ to give a good idea of how an implant is performing. However, for individual surgeons (or even hospitals), where the number of cases is much smaller, this missing data could effect how we interpret their performance.

3D modelling set to transform surgical planning

Above the metal hip joint nestled in this 3D-printed pelvis is a "pseudotumour" – a benign growth that can be painful and sometimes requires surgery. This model shows clearly how the tumour can create pressure on major blood vessels. (Image: Cavendish Imaging)

Above the metal hip joint nestled in this 3D-printed pelvis is a "pseudotumour" – a benign growth that can be painful and sometimes requires surgery. This model shows clearly how the tumour can create pressure on major blood vessels. (Image: Cavendish Imaging)

Surgeons can now see and handle the body parts they will be repairing in the operating theatre before making a single cut, thanks to 3D-printed models. 

The patient in the case shown here required revision surgery of her metal-on-metal hip implant. She had developed a pseudotumour, secondary to metal debris, extending into her pelvis and compressing important structures such as her blood vessels, clearly seen in this 3D printed model (red vessels overlying a brown tumour). 

The model was designed using CT and MRI scans, and helped to make for a successful operation where the pseudotumour was removed without damage to her blood vessels. The use of 3D printed models in medicine looks set to be the future of complex surgery and has been featured in New Scientist.

 

 

3D MRI measuring muscle volume

Researchers from the Royal National Orthopaedic Hospital (RNOH) and University College London (UCL) have created software which automatically measures 3D muscle volume using standard MRI scans, and are the first to validate and apply this software to patients with muscle problems. The software was originally developed to measure the volume of cerebral cortex from MRI which has revolutionised clinical trials in dementia by providing a quantifiable measure of brain atrophy. www.rnoh.nhs.uk