Step-by-Step injections aim to ease chronic pain in Loose-Joint conditions

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults age 18 years or older, any gender. * Symptomatic joint hypermobility or instability attributable to one of the following: 1. hEDS diagnosed using the 2017 International Classification of the Ehlers-Danlos Syndromes diagnostic criteria; 2. HSD classified using the 2017 framework (generalized, peripheral, localized, or historical HSD) with Beighton scoring; or 3. post-traumatic joint instability with ligamentous injury documented by examination and/or imaging. * Objective evidence of instability or clinically relevant hypermobility at one or more target joints, defined as at least one of: 1. a positive joint-specific instability provocation test on standardized physical examination; 2. generalized hypermobility (Beighton score ≥ 5/9 for adults) or documented joint-specific hypermobility at the target joint; or 3. imaging evidence of ligamentous laxity or injury at the target joint (dynamic ultrasound, stress radiograph, or MRI). * Pain attributable to the target joint for at least 3 months. * Baseline pain score of 4 or greater on a 0-10 numeric rating scale. * Failure of conservative treatment, including at least 6 weeks of physical therapy directed at the affected joint(s). * Not currently using NSAIDs and willing to avoid NSAIDs during the active treatment period, when clinically appropriate. * Able to provide informed consent and to comply with study procedures and follow-up. Additional eligibility for the Hyaluronic Acid (HA) alternative pathway - a participant may enter the HA pathway if ALL of the following apply, in addition to the inclusion criteria above: * Has completed at least one regenerative medicine phase (dextrose, PRP, or doxycycline) and either 1. was classified as an inadequate responder at the phase decision point (GPI \< 40%) and declined further regenerative rotation, 2. completed all available regenerative phases without adequate response, or 3. experienced an adverse reaction during a regenerative phase that, in the investigator's judgment, contraindicates further regenerative treatment. * A minimum waiting period of 4 weeks has elapsed since the last regenerative medicine treatment attempted, to allow resolution of post-injection effects before HA administration. * The target joint(s) have clinical or imaging features amenable to HA viscosupplementation (e.g., articular/osteoarthritic pain component identifiable on examination or imaging). * No contraindication to HA (see Exclusion Criteria). Exclusion Criteria: * Impaired decision-making capacity that precludes valid informed consent. * Active local or systemic infection. * Known allergy or contraindication to study injections, local anesthetics, iodinated contrast (if fluoroscopy is planned), or required procedural materials. * Known hypersensitivity or intolerance to tetracycline-class antibiotics, including doxycycline (relevant to the doxycycline treatment phase). * Mast cell activation syndrome (MCAS) or other mast cell disorder that, in the investigator's judgment, elevates the risk of injection-related hypersensitivity or systemic reactions. * Active autoimmune or systemic inflammatory connective-tissue disease that, in the investigator's judgment, may confound the response to regenerative treatment or increase procedural risk. * Known hypersensitivity to sodium hyaluronate or to the specific HA product to be used (Visco-3); active skin disease or infection over the planned injection site; venous or lymphatic stasis in the limb of the planned injection. * Active malignancy or anticancer treatment within the prior 12 months; a prior malignancy in documented remission may be enrolled at the investigator's discretion with documented rationale. * Uncontrolled diabetes mellitus, defined as HbA1c ≥ 8.5% on the most recent value within the prior 3 months; the investigator may also exclude for other objectively documented diabetes-related procedural or healing risk. * Prior joint replacement at the target joint. * Planned surgery during study participation. * Corticosteroid injection to the target joint(s) within the prior 6 weeks. * Concurrent enrollment in another interventional study for the same pain condition. * Active litigation or disability claim related to the target condition (to limit secondary-gain confounding of self-reported outcomes). * Pregnancy, or unwillingness to undergo pregnancy testing when fluoroscopy is planned (persons of childbearing potential). * Inability to comply with study procedures or follow-up.