A system for monitoring a patient includes a sensor unit having a housing and sensors disposed in or around the housing; and a base having a shell and configured and arranged to be adhesively attached to skin of the patient. The sensors can be used to monitor physical therapy and rehabilitation of the patient. The sensor unit can provide information to a patient or clinician device to facilitate the monitoring. The sensor data can be used to determine measurements such as tilt angle of the sensor unit and range of motion measurements (such as extension, flexion, or forces associated with movement) of the anatomical region to which the sensor unit is attached. The sensor data can also be used for automated identification or classification of exercises performed by the patient.