Introduction of a day surgery pathway for Unicompartmental Knee Replacement


To disseminate the success of this innovative new pathway, delaying knee flexion, to a wider audience.

The current emphasis within the NHS is to safely reduce the time patients spend in hospital and perform more operations as day surgery or short stay. Our aim was to reduce the length of stay (LOS) for all unicompartmental knee replacements (UKRs) by introducing a new pathway with an innovative rehabilitation protocol, delaying knee flexion. This was to help reduce post-operative pain and speed up mobilisation to give as many patients as possible the opportunity to be managed as day surgery cases.


2.6 to 1.5 days
Reduction in length of stay
Saved over 12 months


In September 2016 an innovative day surgery pathway was introduced. All UKR patients were assumed as day surgery cases on admission and followed a pathway of minimally invasive UKR surgery, general or spinal anaesthesia and local infiltration. They were mobilised by a physiotherapist, weight bearing as tolerated on the day of surgery and discharged home if they were medically well, had someone to stay with them for the first 24 hours and were safe using crutches and stairs. For the next 4-5 days patients were instructed to keep their knee in extension and perform only static quadriceps and foot and ankle circulatory exercises. They should also keep the post-operative dressings and pressure bandage on until they returned to a day surgery UKR clinic in 4-5 days for a wound check and commencement of knee flexion exercises. Those patients who remained overnight, for whatever reason, and were discharged on day 1 also followed this protocol. Patients who remained in on day 2 commenced knee flexion on that day and were discharged when they were medically well and safe on crutches and stairs.


Eleven orthopaedic consultants and their teams performed 436 primary unilateral UKRs in the 12 months to August 2017. 130 patients (30%) went home on the day of surgery, 180 (41%) on day 1 and 126 (29%) stayed in 2 or more days (range 2-28 days). At the 4-5 day clinic the average fixed flexion deformity (FFD) was 3.9° (range 0-40) and flexion 78° (range 30-115). The 6 week average FFD was 2.8° (range 0-20) and flexion 109° (range 60-135). LOS reduced from 2.6 to 1.5 days (median of 1 day). There were no MUAs required.

Cost and savings

  • Reduction in LOS from 2.6 to 1.5 days (median of 1 day)
  • The physiotherapy restructuring was cost neutral.
  • A saving of 480 bed days and £144,000 was made in 12 months.


Many components of traditional clinical care were altered allowing adoption of this pathway. We feel the important factors were delayed knee flexion, physiotherapists working late evening shifts, a consistent team message and patient education. The changes we achieved were the result of marginal improvements in all areas of the pathway, rather than any one major change.

We have shown that delaying knee flexion until 4-5 days post-operatively does not have any long term effect on knee flexion following UKR. The day surgery pathway was safe and acceptable to patients and allows 71% to be discharged by day 1.

Top three learning points

  1. Delaying knee flexion provided benefits in terms of earlier mobilisation with no short term detriment
  2. A cost neutral restructuring of physiotherapy rotas allowed patients to mobilise and be discharged later in the day.
  3. Providing a consistent team message and patient education.

Funding acknowledgements

We acknowledge the support of the Oxford Biomedical Research Unit.

Additional notes

This work was presented at Physiotherapy UK 2018.

The full paper can be found here

This project was presented at the National Orthopaedic Alliance Quarterly Meeting on 1st August 2018

For further information about this work, contact Cathy Jenkins: