Systematic Review of Free Tissue Transfer Used in Pediatric Lower Extremity Injuries

Mehul Thakkar, MBBS; Bartlomiej Bednarz, MBBS, MA(Cantab)

Disclosures

ePlasty. 2021;21:e2 

In This Article

Discussion

As described previously, lower-limb trauma with corresponding soft-tissue defect poses a great challenge to the reconstructive surgeon in terms of decision making. Before any reconstructive procedures can be undertaken, a thorough initial evaluation of the patient should take place. Subsequent discussions should be had with the patient's parents and/or the child if old enough on the options available, the risks involved, and, most importantly, the lengthy rehabilitation process. The decision to amputate or proceed with limb salvage is a difficult one, and scoring systems such as the NISSSA (nerve injury, ischemia, soft-tissue injury, skeletal injury, shock, and age) score have been developed to aid clinicians in the decision-making process.[14] Ideally, such decisions should be made in a center experienced with treating such injuries ideally with orthoplastic capabilities.

Prior to any reconstruction, initial surgical debridement of any devitalized tissue must be undertaken. Careful evaluation of the condition of underlying soft tissues, bones, nerves, tendons, ligaments, and vessels must be done. The scale of the reconstruction is then appreciated in terms of defect size, recipient vessel availability (size and length outside the zone of trauma), soft-tissue reconstruction required (skin coverage, nerve grafts, bone grafts, tendon reconstruction), and any orthopedic intervention required, with further planning required.[1] The ultimate goal of such reconstructions is to restore form, function, and contour of the limb in question.[15]

Harii and Ohmori[16] conducted the first free tissue transfers in the pediatric population in 1975, and Ohmori et al[17] were able to successfully perform a groin flap in a 3-month-old child in 1977, leading to the advent of pediatric free tissue transfer. One of the limiting factors worrying microsurgeons in pediatric free tissue transfers is the diameter of vessels deemed to be safe for microsurgical anastomosis. Gilbert[18] provided an arbitrary figure of 0.7 mm as the lower limit. However, vessel diameters of between 0.3 and 0.5 mm have been successfully anastomosed[19,20] in the dawn of a new era of "super microsurgery." It is recommended that more than 1 anastomosis is performed when very small vessels are encountered (<0.5 mm) to reduce the risk of failure.[21]

In a series of 106 pediatric free tissue transfers by Canales et al,[22] the flap success rate was 88% and together with minor complication rates this was comparable with the adult population, paving the way for the use of free tissue transfer in the pediatric population. Indeed, with further experience over the last 3 decades in microsurgical soft-tissue reconstruction in children, high flap success rates of between 95% and 100% have been reported.[10] In their systematic review of 439 flaps in pediatric lower-limb salvage following trauma, Jabir et al[21] reported a 5.01% failure rate. This was comparable with our review of 220 free flaps where the overall success rate was 95.5% (10/220), strengthening the case.

Another important conundrum faced is the choice of flap used by the reconstructive surgeon. With a vast array of flaps available in the armamentarium, careful thought and planning are required on which flap will be of most benefit to reconstruct an individual defect. Factors that need to be considered are defect size, length/diameter of the pedicle/recipient vessels, and the need for any neurotization.[1] Ultimately, a considerable amount of judgment and experience is required. The top 5 flaps used in this study included ALT flap, LD flap, scapular/parascapular flap, deep inferior epigastric artery perforator flap, and gracillis flap. The most popular flap was the ALT flap (27%), followed closely by the LD flap (23%). The majority of flaps were fasciocutaneous/perforator flaps, accounting for 65% of flaps in comparison with muscle flaps, which accounted for 33% of flaps. This is similar to the review by Claes et al,[15] in which perforator/fasciocutaneous flaps were a more popular option, with the ALT flap being the most popular choice. Of note, in our study, 28 and 19 (47/51) LD flaps, respectively, were from 2 case series that took place over a period of 38 and 15 years, respectively. Similar to the studies of Claes et al[15] and Jabir et al,[21] this series points to a migration from the use of muscle flaps in earlier studies to the use of perforator-based fasciocutaneous flaps, with the latter becoming more popular.

Advantages of perforator flaps are that they are thin and pliable for reconstruction of the distal part of the leg (ankle, foot, heel, sole), large skin islands can be harvested (eg, thoracodorsal artery perforator flap) with reduced donor site morbidity due to direct closure, can be sensate if neurotized, can be debulked in the future, and have a reliant anatomy. Being thin and pliable are vital in reconstruction of the ankle, foot, and heel due to cosmetic appearance, range of motion required, and also ability to fit into footwear.[21] In contrast, muscle flaps lead to functional loss at the donor site and additional skin grafting is required, further increasing donor site morbidity.[15] Also, muscle flaps can create bulk to fill large dead spaces, add additional vascularity to the wound, and, in select cases, be used as a neurotized free functioning flaps.[15]

In this study, the distal third of the leg (ankle, foot, heel/sole) was the location of the majority of soft-tissue reconstructions (n = 116), followed by the lower leg (n = 42), which again mirrors the systematic review by Jabir et al[21] across most series of pediatric free flaps for lower-limb injuries. This may be due to the fact that there is a shortage of local soft tissue in this mobile region, without much pliability and extensibility and possibly exposed tendons. The majority of pediatric lower-limb injuries are caused by road traffic accidents, and these predominantly involve the foot and ankle, accounting for the pattern described earlier.[23–25] In the United States, approximately 9400 children are treated yearly for lawn mower injuries and 37% of these account for injuries to the lower extremity, feet, and toes.[26] These make up the most extensive lower-limb injuries encountered in the United States.[15]

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