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PIPS diagnosis_consultation

Key information


Patellar Instability: Physiotherapy or Surgery? (PIPS)

Chief Investigator: Mr Andrew Metcalfe

Sponsor: University Hospitals Coventry and Warwickshire NHS Trust

Funder: West Midlands Clinical Research Network

Registration Number: ISRCTN14950321


The knee is the largest weight-bearing joint in the body. It is a complex joint where the shin bone (tibia) and thigh bone (femur) meet creating a “hinge”. The kneecap (patella) is a small, triangular shaped bone located in front of the knee joint. It plays a vital role in helping to bend (flexion) the knee by acting as a “pulley” for the thigh (quadriceps) muscle. Patellar instability is where the patella is displaced, often following an injury. It is an important problem affecting young people, and can be a cause of significant disability.

Following a dislocation of the knee joint, anywhere between a half and 70% of patients will go on to suffer with repeated instability symptoms in the knee. The condition typically occurs in a young, active, working population and can be very disabling. This is due to the painful episodes themselves but also because the feeling of instability causes patients to restrict their activity to avoid further pain or dislocation. UK patients with recurrent instability of their patella are typically managed with either physiotherapy or surgery. There uncertainty about the best treatment, and evidence is needed to help clinicians manage this condition effectively, to ensure that patients get the best results possible.

The aim of this study is to conduct a small randomised study to see if a large study comparing the effectiveness of surgery and physiotherapy in patients with plantar instability is feasible.

Sample size:


Primary outcome:

The Norwich Patella Instability Score

The feasibility of the study will be determined primarily by the recruitment rate, expressed as the number of patients recruited to the study per site per month.


Trial end date is the 15 January 2019.

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PIPS Trial Team
Tel: +44 (0) 2476151407