Participants will utilize a 3D printed knee extender device and an at-home home rehabilitation program designed to be used with the 3D printed knee extender device.

Participants will receive a 3D printed knee extender device with sealed water bottles and an at-home rehabilitation program designed to be used with the 3D printed knee extender device.

Knee extension range of motion is measured by a trained study member who is blinded to the participant's study group using a goniometer. Participants are seated on the exam table with their leg maximally extended. The center of the goniometer is placed over the lateral epicondyle of the affected knee. One of the goniometer arms is aimed proximally, pointing toward the greater trochanter of the hip. The other arm is aimed distally, pointing toward the lateral malleolus of the ankle. The study member then reads the angle created by the arms of the goniometer in this position.

Full knee extension will be measured at home by participants by placing a clicking device under their knee which will produce an audible "click" when the knee is fully extended, and the clicker is depressed. Participants in the control and experimental groups will notify the study team during weekly follow up surveys whether they are able to depress the clicker or not.

Participants knee swelling is measured by a trained study member who is blinded to the participant's study group. Circumference of the knee is used as a proxy for knee swelling, and is measured by wrapping a tape measure around the circumference of the knee just proximal to the superior pole of the patella with resting tension.