Free Composite Serratus Anterior-Latissimus-Rib Flaps for Acute One-Stage Reconstruction of Gustilo IIIB Tibia Fractures

Following the surgical procedure, patients are made non-weight-bearing on the operative extremity until signs of healing are apparent on radiographs. In this case, at the patients’ last follow-up visit, the skin graft was healed, and there was solid fusion of the rib/tibia junction (Figures 4B, 4C).

DISCUSSION

High-energy open injuries to the lower extremities are devastating injuries, with a high rate of late amputation and poor functional outcomes.^11-13 Vascularized bone grafting provides both essential osteoinductive and osteoconductive properties to segmental bone defects in areas with inadequate soft tissue coverage, particularly in the setting of >6 cm of bone loss.^4,14 The results of this study show that acute reconstruction of the lower limb with a composite vascularized SALR graft is a reliable procedure with an acceptable complication profile.

The timing of soft tissue coverage should be performed as soon as the patient is medically stable enough to undergo a reconstructive procedure, ideally within 7 to 10 days; and this timetable has been shown to decrease rates of infection and free flap failure.^15-19 Early coverage provides both control of the soft-tissue envelope and reduces the risk of losing bone.¹ Unlike the timing of coverage, the staging of the procedure is controversial. Proponents of the 2-stage free tissue (soft tissue followed by bony flap) transfer feel that although the tissue may not be infected at the time of coverage, it is contaminated with bacteria at the time of bone reconstruction, and as such is at high risk for both infection and complications.²⁰ Unlike 2-stage procedures, single-stage coverage provides immediate soft tissue coverage, as well as bony support. This reduces the time to bony union and negates the need for repeated surgery in a mangled extremity where secondary surgery is complicated by both scar tissue and altered anatomy.^1,2 Furthermore, it has been shown that there is no difference in the rates of infection when performing a single-stage compared with a 2-stage procedure.⁹ In this study, SALR flaps were typically performed within 2 weeks following an injury as a single procedure. We feel this resulted in the low number of complications in the SALR group.

Unlike free fibulas, rib flaps are easily pedicled with an associated soft-tissue flap due to their blood supply, making them ideal for 1-stage reconstruction. The rib has a dual blood supply: 1 from the posterior intercostal artery, and the other, an abundant periosteal blood supply, from the serratus anterior muscle.⁴ The blood supply to the serratus anterior comes from the thoracodorsal artery, and usually provides 14 cm of a large-caliber pedicle, making it a reliable flap for soft tissue reconstruction.^21,22 Another unique feature of the blood supply to this flap is the amount of soft tissue available for both harvest and transfer; larger portions of serratus muscle and latissimus muscle can be harvested if necessary to cover the soft tissue defect.⁴

Comminuted tibias with segmental bone loss are difficult to manage since they are associated with bony as well as soft tissue defects.^1,12,13,23 These injuries are ideal candidates for a single-stage reconstruction using a vascularized SALR flap. In our series, the use of an SALR flap resulted ultimately in a 100% union and limb salvage rate, with no flap failures and a low complication profile. Unlike the SALR, free fibular flaps must be transferred along with a separate latissimus dorsi flap to provide enough soft tissue coverage necessary for reconstructing large Gustilo IIIB injuries, which could increase the risk of flap failure. Since ribs are composed of membranous bone and have a similar cross-sectional area to both metacarpal and metatarsals, there are concerns regarding the biomechanical properties of ribs for weight-bearing.^4,22,24-26 To compensate for this relatively small cross-sectional area, 2 ribs (either consecutive or alternative) are frequently harvested.^1,4,5,23 Previous studies examining the use of ribs for bony reconstruction have frequently supplemented the rib reconstruction to the tibia using screws and external fixation alone.^1,4,5,23 In our series, all SALR grafts were supported with the use of an intramedullary nail (n = 3) or locked plating (n = 1). The use of this supplemental fixation of the SALR graft allowed our patients to return to full weight-bearing (mean, 6 months) much earlier than the length of time cited in previous reports (12 months) examining these injuries.^1,4,5,23

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