Do Patients Need to See a Physio After Knee Arthroplasty? | The CORKA Trial

The Community Rehabilitation after Knee Arthroplasty (CORKA) trial compared usual outpatient physiotherapy with a multicomponent home based rehabilitation programme but which intervention led to better outcomes?

Knee arthroplasty (replacement) is one of the most common orthopaedic procedures to take place worldwide with largely beneficial outcomes. However 10-15% of patients report little or no improvement in symptoms after surgery the problem is we don’t know how to identify these patients and target their rehab.

Improve your Exercise Selection with Lee Herrington

The most common post-op intervention is out-patient physiotherapy for between 4-6 sessions involving general strengthening, endurance and flexibility exercises with the option of further follow up if required. The variability in what level and duration of service provided post-op is variable and there are concerns this is sub-therapeutic and lacks the required intensity to have benefit.

Therefore a new trial published in BMJ Open, called the CORKA trial, has aimed to compare usual outpatient rehabilitation with an individualised programme targeted towards those who are more likely to have a poorer outcome post op. Additionally the benefit will be to get the intensity and duration of rehab right for all participants


The CORKA trial was a multi centre prospective single-blinded, two arm randomised controlled superiority trial with outcomes being assessed at the start of the trial and at 6 and 12 months. The full trial protocol was published in Trials.

Patients were recruited from 14 different NHS Trusts in the UK and were all 55 years or older and due to have a knee arthroplasty. A standardised screening tool was used in prep clinic appointments to identify those suitable for eligibility and try and identify those at risk of poorer outcome.

The screening tool was based on data from the Knee Arthroplasty Trial dataset and identified those who were at risk of poorer outcome at one year post arthroplasty. Patients were ineligible if they had any preoperative complications, had further surgery planned within the next 12 months and were unable to participate in exercise.

Randomisation took place on the third day post-op or on discharge if earlier. Randomisation was performed using permuted blocks which were 2, 6 and 6 participants in size in a 1:2:1 ratio which prevents prediction of treatment allocation. Once randomised to group patients and clinicians were aware of treatment allocation because of the nature of the interventions. However those taking outcome measures remained blinded.

The primary outcome measure used was the late-life function and disability instrument (LLFDI) function score, with secondary measures the OKS scale, PASE, KOOS, EQ-5D-5L, figure of 8 walking test, 30s chair stand test and single leg stance. This is a lot of outcome measures and more than you would expect in a knee arthroscopy trial suggesting a cast-your-net-wide approach to measuring improvements.

What Was The CORKA Intervention and How Does it Differ From Usual Care?

CORKA is a home-based multi-component rehabilitation programme which consists of an initial assessment with up to six follow up sessions. The interventions started up to 4 weeks post-op but most often started within 2 weeks.

The aim of the intervention was to improve function and participation in activities for people at risk of a poorer outcome after arthroplasty. The main part of the intervention is an individually tailored exercise plan delivered in the patients own home centred around overcoming ‘problematic’ tasks or activities.

The programme also included functional task practice, goal setting and keeping an exercise diary. The initial and middle sessions were delivered by a physiotherapist with the rest by a rehabilitation support worker who was present at the start of the programme.

Usual care was an approximation of the average of all the variations of ‘usual care’ received by patients. This included a minimum of one physio sessions up to a maximum of six with the focus being exercise but could included hydrotherapy or group sessions.


In total 621 participants took part in the CORKA trial with 309 in the intervention group. 37 participants (6%) were lost to follow up. The mean age of participant was 70.4 years and 60% were female.

Participants were deemed as compliant in the usual care group if they attended a single session where as in the CORKA group a minimum of 4 sessions indicated compliance. However the median number of sessions in the usual care group was 4 and in the CORKA group, 5.

Quick Summary of the CORKA trial

  • Home-based multi-component rehabilitation does not provide benefit compared to usual care
  • Using support workers for post-op knee arthroplasty exercise offers flexibility in workforce planning
  • Self-directed rehabilitation is the recommended treatment option for people who have had a knee arthroplasty

There was no improvement in LLFDI between groups with both control and intervention seeing significant improvement in the first 6-months post arthroplasty and minimal provident thereafter.

For all secondary outcome measures there was also no significant differences between the two groups at any time throughout the 1 year of follow up. There were no differences in adverse outcomes between groups either.

The results of this trial are in keeping with a recent NICE evidence review which found no difference in clinically reported outcome measures between group or individual based supervision and self-directed rehabilitation.

Therefore for those who remain well enough and have circumstance which enable them to, self-directed rehabilitation is the recommended treatment option for people who have had a knee arthroplasty.

Hip and knee strengthening course for physiotherapists