Cam Type FAI is a Cause of Hip Pain in the Young Adult and a Precursor to OA

An abnormally formed hip joint (cam deformity) is a major cause of osteoarthritis (OA). Individuals may not experience any symptoms until OA is severe due to extensive cartilage loss and changes in underlying bone. A series of studies showed that the cam deformity can lead to the development of OA if left untreated, thus strongly suggesting a causal relationship. Currently, the cam deformity that causes pain is surgically removed to relieve the pain and treat the associated cartilage damage. Recent studies have demonstrated that surgical treatment leads to bone and cartilage changes that were related to improved function and reduced pain.

This study will allow the investigators to gain a better understanding of the relationship between cartilage and bone changes. The investigators will examine adult participants in the disease state that require surgical correction and compare to age-matched controls. The investigators will look at the impact of surgical intervention through joint-specific biomarkers of OA, specifically the PET-MRI and blood/urine biomarkers, which will allow them to simultaneously query cartilage and bone activity. The investigators propose that the use of PET-MRI will give more sensitive and hip-specific information about the joint health compared to the blood/urine biomarkers in patients with symptomatic cam morphology. Participants will undergo motion analysis and 3D modeling to help the investigators better understand the disease process during the performance of specific activities and define joint contact mechanics as they relate to the PET-MRI imaging, validating a biomarker for early joint degeneration. This diagnostic tool will be extremely useful for younger individuals with a cam deformity who have not yet developed symptoms. In the future the investigators could use this to detect early degeneration in adolescents to prevent and mitigate development of OA later on. This will also help the investigators develop activity guidelines for people with smaller cam deformities in order to avoid surgery and prevent degeneration.

Eligibility Criteria:
Inclusion Criteria:

* Skeletally mature patient undergoing cam resection by hip arthroscopy with hip pain longer than 6 months
* Absence of arthritis (Tonnis Grade 0 or 1)
* Absence of dysplasia (LCEA \> 25°) or overcoverage (LCEA \> 39°)
* Alpha angle greater than 55° on multiplanar imaging
* Subject is over the age of 18 years old at time of enrollment
* Subject is willing and able to complete required study visits and assessments
* Subject is willing to sign the approved Informed Consent Form

Group 2 Inclusion Criteria:

* Normal femoral head neck contour and no evidence of dysplasia
* Subject is over the age of 18 years old at time of enrollment
* Subject is willing and able to complete required study visits and assessments
* Subject is willing to sign the approved Informed Consent Form

Exclusion Criteria:

* Prior joint replacement surgery in any lower-limb joint due to OA
* History of lower-limb joint or back injury in the last year that impairs mobility
* Metallic prosthesis
* Worked with metal, metal fragments in the eye
* Blood transmittable disease(s)
* In vivo devices (Aneurysm clip(s), Pacemaker, ICD, Implanted hearing device)
* Extreme claustrophobia
* Overweight or obese (BMI \> 30) and/or waist circumference \>102cm in men and \>88cm in women
* Diagnosis of Parkinson's or uncontrollable tremors
* Known history of early OA in the immediate family
* Pregnant, Breastfeeding, or planning to get pregnant
* Cognitive impairment that prevents accurate completion of patient-reported outcome questionnaires
* Patient unable/unwilling to complete all required follow-up visits
* Participants who have been exposed to other sources of radiation within the last year (Bringing radiation exposure above annual maximum)