What Constitutes a Successful Hip Replacement?

There are a number of factors that need to be considered when asking the question: “What constitutes a successful hip replacement?” At GaitSmart we have some insights into the answer, and have put together this paper accordingly. I thought I would start this article with a brief overview of the GaitSmart system so that when GaitSmart is referred to in the article, you will be able to put things in context. 

GaitSmart Analysis

GaitSmart Analysis

A little background on GaitSmart 

  • GaitSmart is a sensor-based system that can analyse walking or gait, as well as other functional movements like squatting, jumping and stretching.
  • A GaitSmart analysis and detailed report can be completed in a few minutes.
  • GaitSmart has been validated against the optical gait lab and the GaitSmart results were within one degree of the optical system.
  • GaitSmart systems are in use in education and research, sport and healthcare.
  • GaitSmart has been utilised in a number of published research studies, ongoing as well as completed, at locations including the Royal National Orthopaedic hospital at Stanmore and the Royal Devon and Exeter hospital.

Hip Replacement Causes

The number of NHS total hip replacement operations continues to increase in the UK. There are a number of factors that may drive this and they include:

  • Exercise – The increased numbers of people jogging and attending gyms for exercise means more people are applying increased bio-mechanical loading on their joints
  • Longevity – Improvements in healthcare mean that people are living longer and therefore the pool for potential hip replacements is increasing
  • Obesity – Lifestyle and food choices mean that the number of people that are considered obese has increased dramatically which increases the bio-mechanical loading on the joints.

A survey in the USA showed that the men in the survey took an average of 7192 steps per day and the women took an average of 5210 steps per day. An elite athlete will take in excess of 11,000 steps per day and a number of those will be at speed or involving turning and weight-shifting. Based upon the size of an average stride (2ft 6” or 76cm) it takes just over 2000 strides to walk one mile. If the gait of an individual is not correct then a person could be walking 5000+ steps every day incorrectly. This will have an adverse effect on the joints of an individual.

Hip Replacement Numbers and Costs

At this point in time, there are approximately 80,000 total hip replacements carried out in the UK each year. The average age of patients undergoing hip arthroplasty operations has continued to decrease since 2009. The average cost for a total hip replacement operation in the private healthcare sector in the UK, as of 2014, was £11,800.

As you can see the total cost for hip replacement operations alone, without pre and post treatment care is approximately £944,000,000.

Hip Problems, Pain and the Individual

Hip Joint Pain

In general, most people will not go to the doctor at the first instance of pain. Pain will begin to occur and then slowly increase, and, what tends to happen, is that the individual will begin to alter their gait to alleviate the pain and to continue to perform their regular daily activities.

When a person gets to the stage where they are unable to accomplish normal, daily activities such as dressing in the morning, taking a shower, walking, and getting into bed, then they will seek medical help. It could take a number of years to get to that situation.

The change to the gait of an individual is sub-conscious. It is repeated for many steps per day over, potentially, many years. This gait change becomes a learned behaviour. 

Hip Treatments and Total Hip Replacement

There are a number of treatments available to doctors for patients experiencing hip pain and restricted movement. These include changes in activities, mild painkillers, and physiotherapy. Depending on the age of the patient and the damage to the tissue, the surgeon may suggest arthroscopy or a partial hip replacement before a total hip replacement.

All through this consultation process, the person will continue to walk poorly because of pain. GaitSmart has been used to analyse many individuals that have hip problems and the common change to gait is to swing the affected hip out and round or hip hike, rather than to pull the hip through in a straight line under the body. This movement occurs as it usually reduces the pain for the individual. This means that the opposite leg will take more of the weight when walking, and the swinging motion of the opposite leg causes a rotation of the body, which increases the strain on the opposite knee.

At GaitSmart, we have even analysed patients that came to the doctor with a knee problem and knee pain, but the problem turned out to be the opposite hip. Most people will adapt their way of walking to avoid pain and to be able to cope in their everyday lives.  

What is a Successful Hip Replacement?


A hip replacement operation will usually follow the steps below:

  • The operation will be carried out by the surgeon (approximately 2 hours for a total hip replacement)
  • The stay in hospital will usually be anything up to a week
  • You will receive exercise and movement advice during your stay
  • The surgeon will see the patient approximately 6 – 8 weeks after the operation
  • Physio NHS – Currently outpatient physiotherapy following hip replacement surgery is not routine; often patients are given a home exercise package, but there isn’t always supervised physiotherapy provided on the NHS
  • Physio Private – You will generally have a set number of sessions prescribed
  • You will need to continue the exercises at home
  • Your surgeon may also see you at 12 months post treatment

A published study by Dr. David Hamilton of Edinburgh University found that three factors broadly determine the overall satisfaction rate of a hip replacement:

  • Meeting pre-operative expectations
  • Achieving satisfactory pain relief
  • Having a satisfactory hospital experience

Apart from pain relief, these factors can be managed to some extent. However, because most patients are pleased to be free from pain and provide feedback accordingly, how you walk has taken a backseat as a determining factor in the success of an operation. Also, until GaitSmart, there has not been a practical means to review walking accurately.

GaitSmart and Total Hip Replacements

There are two studies that are currently underway, that use GaitSmart to monitor the movement of patients following hip replacement surgery. The evidence to date shows that while pain has disappeared following treatment, in many cases, gait remains poor. Often, gait improvement is noticeable while the patient is still under the immediate direction of a healthcare professional, but stops improving when the patient has to be self-motivating.

Some people are not aware of issues with their movement post treatment. However, in many cases, friends or relatives have commented on the movement of the patient, suggesting that there is an unbalanced or even a ‘rolling or waddling motion’ to their walk.

The data being collected in studies with GaitSmart is showing that a high percentage of patients continue to walk with the same gait that they had prior to the operation. As mentioned previously, this is a learned behaviour and there is no pain to stimulate a change in the gait again, post treatment, so the gait remains poor.

Poor gait means that the individual is continuing to apply an incorrect bio-mechanical loading on the lower limbs and spine. This, in turn, will lead to further problems for the individual. People are returning to doctors for seemingly unrelated problems with knees, ankles and backs.

We also have evidence that using the data from a GaitSmart analysis, it is possible to help a person to improve their gait by providing the individual with the supporting, objective data. Apart from the report giving the person accurate, quantifiable data, it has a secondary but equally important benefit of being a motivator that empowers the person to continue to achieve, and maintain, a healthy gait. GaitSmart also allows ongoing tracking and monitoring of gait.

Pain versus Gait Function as an indicator of Success?

elderly runner

Of course, pain, or lack of, is a big factor in the success of a hip replacement. Pain was the initial indicator for the individual that there was an issue. They have had to endure increasing pain as the condition has deteriorated and if that pain does not diminish or disappear completely, then they will have to continue to live with pain and therefore could not consider the treatment successful.

However, as explained previously, if there is no pain, but there is incorrect function, then the person will continue to have walking issues, albeit not necessarily with the hip. A good functioning gait should be achieved in order to ensure the best prognosis for continued healthy movement.

At this point in time, Patient Reported Outcome Measures (PROMs), rely heavily on subjective feedback from the patient. There are two reasons for this:

  • It has not been possible to assess gait function accurately nor in a practical way
  • The patient only has pain as a measurement tool

In order to ensure full rehabilitation and a greatly reduced potential for re-admission with a gait related issue, pain and gait function need to be assessed together. Lack of pain does not mean there is not an issue, but it does mean that a person is more likely to have higher levels of activity and therefore will exacerbate any problems.

Assessing gait function will potentially need a paradigm shift in the medical world, because it could add to the complexity of the treatment for the healthcare professionals. Currently, a hip replacement operation could be deemed a success if the pain has diminished. In the future, the same operation would not be deemed a success unless pain had diminished and gait function was good.

A key objective for many of the NHS groups and also Private Health Institutions is to “Deliver excellent clinical outcomes”. In order to do this, function must be considered alongside pain as an outcome measurement.

Lastly, particularly for the NHS, costs are key. The ability to reduce the number of patients re-admitted for a gait related issue will have a huge impact on the costs to the NHS.

GaitSmart is a non-invasive process that can be completed in minutes, including the production of accurate gait data that can be practically applied by any healthcare professional. On-going functional assessment, post hip replacement, would ensure that gait problems are minimised. This could be a service provided in the private healthcare industry or the NHS.

Ultimately, it seems ironic, and unthinkable, that a successful hip replacement could mean you may never walk correctly again.