Analysis of multiple risk factors affecting the result of free flap transfer for necrotising soft tissue defects of the lower extremities in patients with type 2 diabetes mellitus.

BACKGROUND: The limb-threatening large soft tissue defects that occur on the feet of type 2 diabetic patients have complex causes and are less likely to be corrected by free flap reconstruction compared to those in non-diabetic patients. We retrospectively analysed factors affecting the success of free flap transfer for necrotising soft tissue defects of the lower extremities in patients with type 2 diabetes. METHODS: This study included 33 diabetic patients whose feet were treated with free flap transfers. All patients had limb-threatening large soft tissue defects with tendon or bone exposure. The operative results were divided into three groups at 1 month post-operatively: the complete healing group, and the complication group, with either partial necrosis requiring additional simple procedures or flap failure with total necrosis. Nine preoperative factors were analysed: (1) ankle brachial index, (2) HbA1c, (3) BMI, (4) the smoking factor, (5) atherosclerotic calcifications (6) serum creatinine levels (>1.28 mg dL(-1) vs. <1.28 mg dL(-1)), (7) GFR, (8) wound infection and (9) wound defect size. RESULTS: Of the 33 patients, 15 showed complete healing and 18 showed complications of the free flap (eight partial necrosis and 10 flap failure). No atherosclerotic calcifications were found in the patients in the complete healing group, although they were found in 12 patients in the complication group, and this difference was significant (p = 0.002). Patients with serum creatinine levels >1.28 mg dL(-1) had significantly higher free flap transfer complication rates than those with serum creatinine levels <1.28 mg dL(-1) (p = 0.038). CONCLUSIONS: This study analysed the risk factors of free flap reconstruction for limb-threatening large soft tissue defects on the feet of type 2 diabetic patients. Serum creatinine levels >1.28 mg dL(-1) and atherosclerotic calcifications were confirmed as risk factors for flap survival.

Biodegradable internal fixation plates enabled with X-ray visibility by a radiopaque layer of ß-tricalcium phosphate and poly (lactic-co-glycolic acid).

Biodegradable polymer plates can be clinically used as an alternative to metal plates (e.g., titanium) for internal fixation, which, however, are not visible with X-ray imaging, often used for post-operative diagnostics. In this study, therefore, we prepared a biodegradable plate enabled with X-ray visibility by attaching a radiopaque layer on a biodegradable fixation plate in clinical use (Inion, Finland). A radiopaque layer was made of a fine powder of a radiopaque agent, ß-tricalcium phosphate (TCP) and a biodegradable binder material, poly (lactic-co-glycolic acid) (PLGA), which were physically mixed without change in their chemical structure. The radiopacity increased as we increased the layer thicknesses from 0.5 mm to 1.3 mm. Regardless of layer thickness, however, the radiopacity decreased with time both in vitro and in vivo due to decreasing density of TCP in the layer by swelling and degradation of a binder material, PLGA. The in vivo study with rabbits revealed that a discernible image of the radiopaque plate could be obtained by X-ray for up to 21 days, also showing the overall biocompatibility 6 months after implantation. Therefore, we conclude that the radiopaque plate prepared in this work is a promising fixation device enabled with both X-ray visibility and biodegradability.