(1) Patients with diabetic foot ulcers Wagner classification (1) of grades 3–4 (infection damage involving deep tissues but not the ankle) have been ineffective for more than two months through dressing changes, debridement,and standard medical treatment; (2) preoperative CT angiography or angiographic ultrasound demonstrating patency of the superficial femoral and popliteal arteries and patency of at least one branch of the anterior tibial, posterior tibial, or peroneal arteries to the plane of the ankle joint (11); (3) good compliance and complete follow-up data.

(1) Combination of other serious uncontrollable diseases that cannot tolerate the procedure, such as diabetic ketoacidosis, cardiovascular disease, or systemic infection; (2) those with broken and infected skin of the affected lower leg or tibia with an internal fixation device; (3) those who have serious psychiatric disorders and cannot cooperate with the external frame adjustment. [This study was approved by the Medical Ethics Committee of Chongqing Yubei District People's Hospital (No. 2022C1), and all signed an informed consent form before surgery].

Nineteen patients with diabetic foot ulcers were included in this study. DFU treated with the tibial transverse transfer technique were classified as the transfer group (8 cases), including 5 males and 3 females. The DFU treated with the periosteal distraction technique was classified as the distraction group (11 cases), including 7 males and 4 females. All patients were followed up for approximately 4.8–12 months, with a mean of 8.4 months. No statistically significant differences were found in comparing general information and preoperative wound wanger grading between the two groups (P > 0.05) (Tables 1, 2).

(1) If there is no contraindication for all patients to improve the Computed Tomography Angiography (CTA) of the lower limbs after admission, a color Doppler ultrasound of arteriovenous vessels in the lower limbs should be performed to understand the vascular occlusion if the CTA cannot be improved. (2) The diabetic diet plan was formulated jointly with the Endocrinology Department before the operation, and the joint ward round was conducted at least once a week to regulate blood glucose. The blood glucose control standards were as follows: 2 h after meals, blood glucose ≤10.0 mmol/L, fasting blood glucose ≦8 mmol/L, and albumin level ≥30 g/L. (3) Culture the wound secretions, and the Joint Infection Department selected antibiotics according to the culture and drug sensitivity results and dynamically followed up to adjust the medication.

The transfer group: after satisfactory anesthesia with lower limb nerve block without a tourniquet, routine disinfection, and towel laying. A 3 cm-long curved incision was made on the medial side of the tibial tuberosity about 5 cm distal to the periosteum (without cutting the periosteum) to determine the extent of the transverse tibial bone transfer and osteotomy (5.0 cm in length and 1.5 cm in width). A 2.5 mm drill was used as a guide to making successive holes at 2 cm intervals within the predetermined bone window, and a 4 mm stainless steel half-pin was screwed in to transfer the bone. Then, a bone knife was used to pry the displaced bone block along the drilled hole to move the bone window up and down. A 0.5 mm external fixation stainless steel half-pin was screwed into each of the proximal and distal tibias at about 1 cm of the bone window (penetrating both layers of the cortex). The bone transfer device was assembled and fixed firmly, and the subcutaneous tissue and skin were sutured. After surgery, the distal diabetic foot wound was cleared, and Vacuum Sealing Drainage(VSD) negative pressure suction was placed to promote wound healing according to the condition of the wound. On the third postoperative day, the external fixation brace was adjusted for bone transfer, and the bone block was first moved outward at a rate of 0.5 mm/24 h. After moving for 14 days, the bone was left standing for three days, and then moved back at the same speed. After the transfer, the external brace was fixed for 6–8 weeks until the bone window healed and the external brace was removed.

The distraction group: after satisfactory anesthesia with lower limb nerve block without a tourniquet, routine disinfection, and towel laying. A longitudinal incision of approximately 1 cm was made on the anterior medial side of the proximal calf (4 cm below the tibial tuberosity and 1 cm medial to the tibial spine), and the tissue was separated to reach the periosteum. The periosteum is incised transversely with a sharp knife for approximately 1 cm. Then, the periosteum is gently dissected up and down along the tibial stem with a special periosteal stripper to the length of the pre-inserted plate, avoiding excessive dissection that may result in insufficient postoperative retraction. Then, four quadrants were established with the skin and periosteal incision as the longitudinal and transverse axes. A 2.0 mm drill was used to penetrate the unilateral bone cortex at each of the four quadrants to perform medullary decompression, followed by the insertion of a 0.8cm × 0.8 cm distraction plate at the periosteal incision, all of which were inserted distally and moved in the opposite direction until the midpoint of the plate was confirmed to be at the periosteal incision and the midline of the upper and lower margins of the tibial stem. A flat-headed hollow screw was screwed into the middle of the plate, followed by a 1.5 mm kerf pin in the hollow screw hole and penetrating the contralateral bone cortex to fix the plate and the hollow screw, and after satisfactory fixation, C-arm fluoroscopy ensured that the distraction plate was placed along the midline of the anterior and posterior margins of the tibial stem and that the screw and kerf pin was well positioned. Finally, the periosteum was observed to lift with the screw plate by twisting the caudal cap of the hollow screw clockwise. The cremaster's pin was cut parallel to the caudal cap of the screw so that the caudal end was just over the retractor screw by approximately 0.2 cm. The periosteum was closed with 3-0 absorbable sutures, and the incision was fully closed. A distal diabetic foot debridement was then performed. The retraction of the periosteum was started on postoperative day 3, with a clockwise retraction rate of 0.25 mm/12 h per day, and the retraction screws and plates were removed after 20d of continuous retraction. The patient was allowed to leave the bed for daily activities during the retraction period. The dressing of periosteal stretch wound was changed every two days, and the external nail canal was disinfected with 75% alcohol every day to prevent nail canal infection. (The surgical tools of Zhejiang Kehui Medical Devices Co.).

Before operation, 14 days, 28 days and 90 days after move, the pain score (NRS) method (from 0 to 10, patients are required to choose a value representing their pain, 0 means no pain, the higher the value, the greater the pain) was used to record the operation time, blood loss and pain sensation in the operation area of the two groups. Then skin temperature, ankle-brachial index (ABI) and percutaneous oxygen partial pressure (TcPO₂ > 40 mmHg: no bloody lesions; 21 mmHg–39 mmHg: mild ischemic lesion; TcPO₂ < 20 mmHg: severe ischemic lesion (12) to evaluate the peripheral circulation of the affected limb. Semmes-Weinstein Monofilament (SWM) is used to evaluate the improvement of neuropathy around diabetic foot ulcer (covering patients’ eyes, placing monofilaments with different specifications perpendicular to the affected foot, and uniformly exerting force to bend the monofilaments to 90 degrees, and the position that can be correctly perceived twice in three consecutive times is “+”. Normal specification (1.65–2.83), mild tactile hypoesthesia (3.22–3.61), protective sensory hypoesthesia (3.84–4.31), protective sensory loss (4.56–6.65) and total sensory loss (specification >6.65) (13).The progress of pain in the affected limb was evaluated by visual analogue scale (VAS). Finally, the healing time of diabetic foot wound, limb preservation rate and complications (nail infection, displaced site fracture and skin necrosis in operation area) were observed and recorded in the two groups.

5 ml of fasting peripheral venous blood was drawn before surgery and at 7:00 am on the 7 days, 21 days, and 35 days after the start of the move and placed upright for a moment to allow the whole blood to clot; the serum and blood cells were separated by centrifugation at a radius of 10 cm and 2,000 r/min for 10 min, and 1.5 ml of the supernatant was placed in a centrifuge tube and stored at −80℃ in a refrigerator. The levels of VEGF, bFGF, EGF and PDGF were determined by enzyme immunoassay kits (provided by Hangzhou Biotechnology Co, Ltd.) using vascular endothelial growth factor (VEGF), essential fibroblast growth factor (FGF), epidermal growth factor (EGF) and platelet-derived growth factor (PDGF).

SPSS 23.0 statistical software was used for statistical analysis, and the measurement data were expressed as (X±s), and t-test for independent samples was used for comparison between two groups, and a variance test was used for comparison between three groups. The rank sum test was used for the comparison of hierarchical data. All test levels α = 0.05.

The operative time, intraoperative bleeding and pain score in the operative area were significantly less in the distraction group than in the transfer group, with statistically significant differences (P < 0.05). The intra-group comparison between the two groups revealed that the skin temperature ABI, TcPO2, SWM and VAS of the affected limb were significantly improved compared with those before surgery, and the difference was statistically significant (P < 0.05). No statistically significant differences were found in skin temperature, ankle-brachial index, TcPO2, SWM and VAS between the two groups of patients compared at the corresponding time points preoperatively and postoperatively (P > 0.05). All wounds were healed in both groups, with healing times ranging from 15 to 41 days, with a mean value of 28d. The limb preservation rate was 100%. There were two complications in the transfer group: One patient in the displaced group had a fracture in the osteotomy area, and a nail tract infection accompanied one patient. All patients in the distraction group were successfully discharged from the hospital with the external frame support removed. (Tables 3, 4; Figures 1, 2).

The expression levels of VEGF, bFGF, EGF and PDGF were significantly higher in both groups compared with the preoperative levels, and the differences were statistically significant (P < 0.05). There was no statistically significant difference in the expression levels of VEGF, bFGF, EGF and PDGF between the two groups at the corresponding time points before and after surgery (P > 0.05). Each index increased with the increase of retraction intensity. The increasing trend was delayed after removing the retraction outer frame in both groups at 35 days after the move, and the levels of EGF, bFGF and PDGF decreased compared with those at 21 days after the move. (Table 5; Figure 3).