Subgroup analysis on pain and function outcomes of post-operative exercise therapy in patients with knee osteoarthritis


Osteoarthritis (OA) is a common disorder in the ageing people, which mostly affects the knee joint. Several treatment options are available to reduce pain or improve knee function with a possibility of surgical interventions at end-stage knee OA, taking complications and comorbidities into account. Exercise therapy (ET) is one of the non-surgical, non-pharmacological therapy interventions with beneficial effects, recommended by international clinical guidelines. Several studies have shown a beneficial effect of ET on pain, stiffness, muscle weakness and physical function. Still it is unknown which patients benefit from ET given post-surgery, as the overall effects of postoperative ET are rather small and patients with knee OA consist of an heterogeneous group.

Therefore this study aims to identify subgroups of patients with knee OA who have better outcome after postoperative ET compared to usual care.


We will perform an individual patient data (IPD) analysis with IPD data of relevant published randomized controlled trials (RCTs). We will conduct a systematic literature search through several literature databases. We will include interventions involving any form of supervised, repetitive and structured postoperative exercise therapy in comparison to usual care. The primary outcome will be the difference of self-reported pain and knee function 6 months post-surgery and post ET on a WOMAC/KOOS scale between the subgroups and the secondary outcomes are pain and physical function measured at other time points and scales, hospital stay duration, adverse events, analgesic use and quality of life.

The subgroups will be defined based on age, sex, body mass index (BMI), severity of pain and physical disability, muscle strength, mental health complaints, presence of comorbidities, daily physical activity, radiographic involvement of patellofemoral compartment and swelling of the knee joint.

For all eligible trials, the lead investigators will be invited to share anonymized IPD. The data will be pooled if the exercise interventions are homogenous and analysed using a two-stage approach to evaluate the treatment effect in different subgroups.


Ongoing. We are currently screening studies for inclusion to our review.

Protocol and publications


R.U. (Upasna) Sharma 1
J. (Jos) Runhaar1
K. (Koen) P. Bos 2
D. (Desirée) M.J. Dorleijn 3
M. (Marijn) Vis 4
P. (Patrick) J.E. Bindels 1
M. (Max) Reijman 2
M. (Marienke) van Middelkoop 1, 5
S. (Sita) M.A. Bierma-Zeinstra 1, 2

1. Erasmus MC Medical University Center Rotterdam, Department of General Practice, The Netherlands
2. Erasmus MC Medical University Center Rotterdam, Department of Orthopedics & Sports Medicine, The Netherlands
3. University Hospital Ghent, Department of Orthopedics, Belgium
4. Erasmus MC Medical University Center Rotterdam, Department of Rheumatology, The Netherlands
5. OA Trial Bank Steering Group, Rotterdam, Netherland