CARTIZ

3. Presence of at least one objectively documented musculoskeletal manifestation - current or historical - defined as any of: (i) inflammatory arthralgia affecting one or more joints with clinical, imaging, or serological support; (ii) CASPAR-positive psoriatic arthritis; (iii) radiographically documented knee osteoarthritis; (iv) enthesitis on physical examination or ultrasound; (v) documented inflammatory arthropathy of the spine or peripheral joints with a specialist diagnosis.

4. For the retrospective-prospective component: availability of clinical documentation of articular state prior to tirzepatide initiation in the patient's medical record. Documentation may include physical examination notes, imaging, laboratory values, or specialist consultation notes.

5. Signed informed consent for registry enrolment, longitudinal serum biobanking, HLA typing at INCMNSZ, quantitative knee MRI with T2 mapping at Ci3M UAM-Iztapalapa at Week 0 and Week 52, non-contrast cardiac CT at INCar at Week 0 and Week 52, multi-frequency bioelectrical impedance analysis at Universidad La Salle México at six timepoints, and (where applicable) medical record review. Each attestation is consented modularly within a single document.

6. Clinical plan to continue tirzepatide for at least 52 weeks from registry Week 0, based on the treating physician's evaluation of current clinical indication. Discontinuation during follow-up is captured as an outcome variable and does not remove the patient from the registry.

7. Capacity to attend scheduled follow-up visits and to undergo bilateral knee MRI at Ci3M (without severe claustrophobia requiring sedation, without absolute contraindication to MRI - see Exclusion 6) and non-contrast cardiac CT at INCar (without uncontrolled arrhythmia precluding ECG-gated imaging of diagnostic quality).

For the Surgical Tissue Subcohort (Cohort 3) only - additional criteria applied at the time of subcohort enrolment:

8s. Scheduled clinically indicated cardiac surgery at the Instituto Nacional de Cardiología Ignacio Chávez (coronary artery bypass grafting, valve replacement, or combined procedures) during registry follow-up.

9s. Specific additional informed consent for intraoperative collection of epicardial adipose tissue fragments.

2. Major joint surgery within the 3 months prior to Week 0, or planned major joint surgery within the 12 months following Week 0, involving any joint scheduled for evaluation in the registry.

3. Intra-articular corticosteroid or hyaluronic acid injection within the 6 weeks prior to baseline biospecimen collection in any joint. Patients beyond the 6-week washout are eligible.

4. Active malignancy, with the exception of adequately treated non-melanoma skin carcinoma. History of malignancy in remission ≥5 years is permitted at the discretion of the treating investigator.

5. Current pregnancy, lactation, or planned pregnancy within the 12-month observation period.

6. Absolute contraindication to MRI, including non-MRI-compatible cardiac pacemaker or implanted defibrillator, ferromagnetic intracranial vascular clips, non-documented non-MRI-compatible cochlear implants, or other contraindication per the local MRI safety protocol.

7. Systemic rheumatologic disease other than psoriatic arthritis or osteoarthritis requiring active immunomodulation, specifically: seropositive rheumatoid arthritis on biologic therapy, active systemic lupus erythematosus on immunomodulation, active vasculitis on immunosuppression, or other systemic disease whose treatment confounds the inflammatory axis the registry is designed to characterize.

8. Inability to provide informed consent (cognitive impairment, language barrier not resolvable with site interpreter, or other incapacity to understand the protocol), or anticipated inability to complete the 52-week follow-up.

For the Surgical Tissue Subcohort (Cohort 3) only - additional exclusions:

9s. Prior major cardiac surgery resulting in extensive pericardial adhesions that preclude safe intraoperative EAT fragment collection, as assessed by the operating cardiac surgeon.

10s. Emergency cardiac surgery precluding the specific informed consent process.