Method of treating lower back pain

A method of treating a subject with early-stage degenerative disc disease (DDD) characterized by an intervertebral disc (IVD) exhibiting Grade II or III on the Pfirrmann scale, comprising:

• i) providing an injection device comprising:
• an activatable reservoir containing an activatable composition comprising an active precursor component;
• an activator reservoir containing an activator composition comprising an activator agent, which promotes physical and/or chemical transformation of the active precursor component into an active component;
• and
• a mixing chamber with an outlet;
• wherein the activatable reservoir and the activator reservoir maintain separation between the activatable and activator compositions;
• ii) operating the injection device to simultaneously:
• deliver the activatable composition from the activatable reservoir and the activator composition from the activator reservoir into the mixing chamber to form a treatment composition;
• and
• inject the treatment composition, via a needle or cannula, into a nucleus pulposus of the IVD;
• wherein the combined volume of the activatable composition and activator composition used to form the treatment composition is between 0.1 and 3 mL;
• mixing the activator composition with the activatable composition causes the active precursor component to swell and gel;
• wherein the active precursor component physically and/or chemically transforms into the active component to provide, within the nucleus pulposus of the IVD, a non-biodegradable post-treatment composition comprising the active component;
• wherein both the active precursor component and the active component exhibit pH-sensitive swelling and gelling properties;
• wherein the post-treatment composition is relatively less fluidly mobile than the treatment composition;
• wherein the treatment composition is fluidly mobile and the post-treatment composition is a gel.