A common surgical approach used for hip replacements carries higher risks of worse outcomes and should not be routinely adopted by trainee surgeons, a new analysis suggests.
The study found significantly worse outcomes associated with so-called lateral procedures to the hip joint, in which surgeons access the hip by detaching muscle from the side of the thighbone (femur). Lateral procedures were compared with alternative methods in which the surgeon approaches the hip from in front of (anterior approach), or behind (posterior approach), the thighbone.
Analysis of 723,904 hip replacement operations performed between 2003 and 2016 found that lateral procedures were associated with more deaths and a greater risk of further hip surgery.
The researchers suggest it is probably unwise to ask experienced surgeons to change from using the lateral approach. However, new surgeons should be taught to use other approaches when performing hip replacements.
What’s the issue?
More than 100,000 hip replacement operations are carried out in the UK each year, and surgeons can access the hip joint using different approaches. The most commonly used is the posterior approach, in which surgeons access the hip from behind the thighbone. Other approaches include accessing the hip from in front of the thighbone (anterior) or, in about one in three operations, surgeons use the lateral approach and reach the hip by detaching muscle from the side of the femur. Each approach can be performed through a small (minimally invasive) cut or a standard, longer cut.
The different approaches cause different amounts of soft tissue damage and bleeding. It has been assumed that patients’ recovery, their chances of needing further surgery, and the potential adverse outcomes will be influenced by the approach used. But, before this study, there was little large-scale evidence to assess and compare the outcomes from all of the different surgical approaches.
The study used data collected by the National Joint Registry to identify 723,904 primary total hip replacements carried out between 2003 and 2016 in England, Wales, Northern Ireland and the Isle of Man.
It cross-referenced these data to reports of how the patients fared after surgery. Specifically, it looked at the risk of further (revision) surgery in the long-term, and the risk of death three months after surgery. Data on patient-reported outcomes such as pain, mobility and adverse outcomes six-months after surgery were also reviewed. The study compared these outcomes for each surgical method.
Statistical analysis suggested the lateral approach had worse outcomes than the posterior approach.
Compared to the posterior approach, the lateral approach:
- was predicted to have an increased risk (between 5% and 12%) of revision surgery at 12 years
- was predicted to have a 15% increased risk of death within three months of surgery
- was associated with only slightly more reports from patients of pain and mobility issues.
Overall, the study found that the posterior approach had the lowest risk of revision surgery.
Lateral or anterior approaches carried out using minimally-invasive techniques carried an increased risk of further surgery, but the difference was less certain in models accounting for patients' body mass index. The researchers therefore said the data supported the continued use of minimally-invasive techniques at this time.
Why is this important?
This is the largest study to compare the outcomes from the different ways of performing a common operation. The study was observational and cannot prove that the surgical approach caused the differences in outcomes. However, the data strongly indicate worse outcomes with the lateral approach. It was associated with more deaths and a greater risk of revision surgery.
More than 20,000 hip replacements are performed each year in the UK using the lateral approach, and the study authors argue new surgeons should not routinely use it.
A better option, they say, is posterior approach surgery, which is already the most common. At present, NICE guidelines state surgeons can choose a posterior or lateral approach for hip replacement.
The study authors say their findings parallel those from small studies and should be used to inform clinical practice when NICE and other bodies update guidelines. They suggest that surgeons should be steered away from the lateral approach for hip replacement. The posterior approach should be considered the preferred standard approach, they say, and should be used in training new surgeons. They acknowledge that it might be difficult to safely convert experienced surgeons familiar with the lateral approach to a new approach.
Ideally, the findings of this large but observational study would be checked in a randomised controlled trial. Such a trial could compare the possible benefits of the minimally-invasive posterior approach, the conventional anterior approach and the conventional posterior approach. The present study suggests that these approaches may have the best outcomes.
You may be interested to read
The full study: Blom AW, and others. The effect of surgical approach in total hip replacement on outcomes: an analysis of 723,904 elective operations from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. BMC Medicine. 2020;18:242
Study from the same group looking at surgical techniques: Matharu GS, and others. The Effect of Surgical Approach on Outcomes Following Total Hip Arthroplasty Performed for Displaced Intracapsular Hip Fractures An Analysis from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. The Journal of Bone and Joint Surgery. 2020;102:21-28
NICE guidance: Surgical approaches for primary elective hip replacement (NG157) (2020), advises in Section 1.8.1 to consider a posterior or anterolateral approach for primary elective hip replacement
The study was supported by the Healthcare Quality Improvement Partnership, National Joint Registry and the NIHR Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust.