Postoperative volume maintenance rate of microvascular free flap in oral and maxillofacial region: Systematic review and meta-analysis.

[BACKGROUND AND OBJECTIVES] The resorption of flap's volume can be frequently observed in the transplantation of microvascular free flaps, which could significantly affect postoperative function. Therefore, it's essential to comprehend the postoperative flap volume and the mechanisms behind before making clinical decisions.

[METHODS] Literature search was conducted from database on PubMed, EMBASE, Cochrane Library, Chinese database and Google Scholar. A random effects model meta-analyses and descriptive systematic review were performed.

[RESULTS] The search identified 420 articles, of which 9 studies included in meta-analysis and 14 studies included in descriptive systematic review. Postoperative flap volume maintenance rate is used to represent the volume change. The pooled mean postoperative flap volume maintenance rate was 62.82 % for soft tissue flap (95 %CI: 58.83 to 66.82, p = 0.076, I=56.3 %) and 85.96 % for bone flap (95 %CI: 84.19 to 87.73, p = 0.274, I=20.4 %). Weight loss, muscle atrophy, and decreased serum albumin levels are risk factors for postoperative volume reduction of soft tissue flaps. The bone resorption rate of bone flaps in women is higher than that in men.

[CONCLUSION] When designing microvascular free flaps for oral and maxillofacial surgery, soft tissue flaps should consider an anticipated postoperative shrinkage of 37 %, while bone flaps should consider an anticipated postoperative shrinkage of 14 %.