This study will utilize the Moxy wearable sensor to measure muscle oxygen saturation levels in athletes following lower extremity surgery (ACL or Hip arthroscopy) to evaluate their Return-to-Play. The acquired data will complement current protocols utilized by Dr. Voos and Dr. Salata in this regard and will add quantifiable evidence to enable a robust measurement of the surgical limb versus non-surgical limb.

Patients with a diagnosis of ACL tear or hip pathology will undergo surgery. Following surgery, patients will report to clinic for scheduled physical therapy per their institution's injury-specific physical therapy protocol. At set time points (6-week, 12-week, 6 months, and 9 months) during their recovery, patients will be assessed for muscle oxygen saturation and hemoglobin levels with the Moxy sensor. This sensor is a non-invasive device placed over the rectus femoris to monitor oxygen and hemoglobin levels. The patient will then follow the therapy as instructed by the physical therapist and perform the protocol-specific exercises with the sensor in place. The measured parameters will be recorded and stored per patient.

The injured patients will be compared to healthy control patients undergoing a similar one-hour exercise session while wearing the Moxy sensor for comparison of results.

The goal of this study is to use the data obtained from the Moxy sensor device to further predict recovery of function in muscles supporting injured soft tissues to determine safe return to sport.

Inclusion Criteria:

• Age range: Patients age 14 to 30 years
• Patients with ACL injury requiring surgical correction
• Patients undergoing arthroscopic hip surgery
• Healthy individuals with no history of ACL, arthroscopic knee or arthroscopic hip surgery

Exclusion Criteria:

• Patients below 14 years or above 30 years
• Non-English-speaking subjects
• Pregnant individuals