Is the Medial Sural Artery Perforator Flap A New Workhorse Flap? A Systematic Review and Meta-Analysis

Purpose: The medial sural artery perforator (MSAP) flap offers thin, pliable tissue with a relatively long pedicle. Compared to other thin fasciocutaneous flaps, its relatively low donor site morbidity makes the MSAP flap a valuable option for the reconstructive microsurgeon. The purpose of this study is to systematically evaluate the literature on use of MSAP flaps with regards to flap characteristics, indications, recipient site defects, and postoperative outcomes.

Methods: A systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Three electronic databases (Pubmed, Embase (OVID) and Cochrane CENTRAL) were queried. All patients who underwent MSAP flaps with the following outcomes of interest were included: flap failure/success, flap/vessel dimensions, and complications. Descriptive analysis was performed on pooled flap characteristics. Effect size (z-values), odds ratios (ORs) and heterogeneity scores (Q and I² statistics) were calculated for meta-analysis when possible. Multivariate logistic regression was performed to identify factors associated with increased complication rates.

Results:

Thirty-five studies encompassing 526 MSAP flaps were included for analysis. The most common reasons for surgery were oncologic (47.6%) and traumatic injuries (31.8%). The oral cavity was the most common recipient location (45.5%). Average flap dimensions were 6.0 ± 2.3cm by 9.8 ± 3.6cm with an average pedicle length of 10.1 ± 6.6cm. Meta-analysis revealed an overall complication rate of 14.3% (Q value=22.16, p=0.877, I²= -39.9). Use of chimeric MSAP flaps was associated with significantly higher rates of complications (OR=3.92, p=0.039, 95% CI 1.10-13.89). The majority of flap donor sites were closed primarily (68%) versus 32% that were covered with a split-thickness skin graft (STSG). A flap width greater than 5.75cm had an OR=5.3 (95% CI, 1.3-21.8; p=0.014) of having a donor site complication if closed primarily.

Donor site complication rate was 1.9% (n=10) overall. Out of 247 MSAP flaps, 68% were closed primarily versus 32% covered with a split-thickness skin graft (STSG). Average dimensions for flaps whose donor site was closed with a STSG (8.0cm by 12.2cm) was significantly greater than those closed primarily (5.0cm by 8.9cm, p<0.0001). Among those that underwent primary closure, a flap width greater than 5.75cm had an OR=5.3 (95% CI, 1.3-21.8; p=0.014) of having a donor site complication. There was no significant difference in donor site complications based on patient gender or use of primary closure versus STSG.

Conclusions: This is the first systematic literature review and meta-analysis demonstrating the efficacy and safety of the MSAP flap. Our results emphasize the utility of the MSAP flap as a potential workhorse flap for various recipient sites requiring thin, pliable tissue and a relatively long pedicle. With a favorable donor site that can be closed primarily in a flap width of nearly 6cm, the potential benefits of this flap cannot be understated.