AbstractBackgroundDiabetic foot ulcers often affect tendon tissue. Consequently, the infection may spread proximally along the tendon, leading to amputation or even the death of patients. Exposed, degenerated, and necrotic tendons are key factors affecting the healing of diabetic foot ulcers. The effective treatment of the tendon involvement may positively affect the prognosis. In clinical practice, treatment with Shengji ointment and bromelain induces islands of granulation tissue on the denatured tendon surface, which gradually grows and merges. Ideally, the exposed tendon is covered entirely by granulation tissue.This trial aims to assess the effect of a combined treatment regime of Shengji ointment, which has been shown to regenerate muscle tissue and pineapple protease in preventing the loss of function and amputation caused by tendon necrosis. This trial will provide high-quality evidence for the effectiveness of this combination in healing diabetic ulcers with tendon necrosis.MethodsThe sample size will be 180 patients who will be randomly assigned 1:1 to a treatment group (90 patients) using Shengji ointment combined with bromelain and a control group (90 patients) using hydrocolloid dressing. Both groups will continue their conventional treatments, such as blood glucose and blood pressure medication, lipid regulation, antiplatelets, and others. The primary outcome will be the wound coverage with granulation tissue. Secondary outcomes will be the wound healing rate, amputation extent (where needed), time to granulation, and the Maryland Foot Score. Other efficacy outcomes will be the time to debridement of necrotic tendon tissue and granulation tissue score.DiscussionThis study will treat patients with diabetic foot ulcers with exposed, degenerated, and necrotic tendons with Shengji ointment and bromelain. The trial aims to promote regeneration and healing, to preserve the limb and its function, and to develop a comprehensive and effective protocol that can be applied to promote the healing of exposed tendons in diabetic foot wounds.Trial registrationChiCTR2000039327; date of registration: 2020-10-23.