The Investigators are investigating a continuous passive motion device to exercise the knee of young children with arthrogryposis after they have had knee surgery.

The investigators will measure the effect of continuous passive motion (CPM) of the knee joint post-surgery on young children with arthrogryposis. The investigators have developed a motorized brace that will move the joint through a prescribed range of motion and speed while the subject is seated. The objective of this pilot study is to develop the device from subject feedback and determine the right dose and speed of CPM to provide. CPM is routinely used for adults and older children after surgery to maintain range of motion. The machines used are too large for young children therefore the investigators have developed a prototype for small sized kids that will exercise their knee joint post-surgery.

Inclusion Criteria:

• Children with arthrogryposis
• Children between 3 and 7 years of age
• Children who have had recent knee surgery

Exclusion Criteria:

• Children older than 7
• Children unable to cooperate with protocol steps