Free Composite Serratus Anterior-Latissimus-Rib Flaps for Acute One-Stage Reconstruction of Gustilo IIIB Tibia Fractures
Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.
Dr. Houdek and Dr. Sems are Assistant Professors of Orthopedics, Dr. Wagner is an Upper Extremity Fellow, Dr. Watts is an Orthopedic Surgery Resident; and Dr. Moran is a Professor of Plastic Surgery and Orthopedics, Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota. Dr. Houdek was a resident at the time the article was written.
Address correspondence to: Steven L. Moran, MD, Mayo Clinic, Division of Plastic and Reconstructive Surgery, 200 First St. SW, Rochester, MN 55905 (email, firstname.lastname@example.org).
Am J Orthop. 2018;47(6). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
Gustilo IIIB injuries of the tibia with segmental bone loss continue to be a difficult reconstructive problem. The serratus anterior-latissimus-rib (SALR) composite flap consists of bone and muscle; this flap can provide soft tissue coverage and vascularized bone in a single surgical procedure. The purpose of this study is to describe the use of the SALR flap for the treatment of a large open tibia fracture with segmental bone loss, with a specific focus on postoperative complications, limb salvage, and time to union.
We reviewed the medical records of patients undergoing an SALR flap (n = 5) for the treatment of Gustilo Type IIIB tibia fractures within 1 month of injury. We compared the mechanism of injury, injury severity score, time from injury to free tissue transfer, complications, and time to radiographic and clinical union.
All patients were male, with a mean age of 25 years. On average, patients underwent free tissue transfer within 1 week of injury. The average time to radiographic union was 7 months. Two patients underwent reoperation. There were no graft failures.
Free SALR flaps can be a useful option for the treatment of high-energy tibia fractures with extensive soft tissue and bone loss. These flaps provide immediate osseous and soft tissue reconstruction with an acceptable complication profile.
- Gustilo IIIB injuries with segmental bone loss can be difficult to treat with conventional means.
- Vascularized bone grafts are beneficial for reconstructing bone defects >5 cm.
- The SALR composite flap consists of bone and muscle.
- This flap can provide soft tissue coverage and vascularized bone in a single surgical procedure.
- In this study, the use of the SALR composite flap was capable of healing large segmental bony defects at an average of 7 months.
Reconstruction of the lower extremity following Gustilo’s grade IIIB injuries is difficult due to loss of both combined soft tissue and segmental bone loss. Since these injuries necessitate the need for soft tissue flap coverage along with vascularized bone grafting, free fibula flaps have classically been used for reconstruction.1-3 In the setting of bilateral lower extremity injury, the contralateral fibula is often not appropriate to harvest and transfer; therefore, other sources of vascularized bone grafts must be utilized including vascularized iliac crest and rib.1-5 The vascularized iliac crest graft is insufficient to provide the bony reconstruction of bone defects >6 cm to 7 cm and does not have a reliable skin paddle.4 In contrast, free composite serratus anterior-latissimus-rib (SALR) flaps can provide both long segments of vascularized bone and abundant soft tissue coverage for large segmental defects.1-5
Free fibula grafts have been considered the gold standard for the reconstruction of large (>6 cm) bone defects.6 In cases of “mangled extremities,” bone defects are associated with large soft tissue defects, which require either single-stage surgery consisting of 2 separate free flaps (ie, free fibula and free latissimus) or a 2-stage procedure where the soft tissue reconstruction precedes the bone reconstruction.2,7-9 Unlike free fibula and latissimus flaps, composite SALR flaps provide both osseous reconstruction and soft tissue in 1 flap supplied by a single vascular pedicle; unfortunately, outcomes using this flap for large Gustilo IIIB injuries are limited.1-5 The purpose of this study is to examine the use of free composite SALR flaps for soft tissue coverage in cases of Gustilo IIIB injuries with large soft tissue and bony deficits. This study specifically examines time to union, need for reoperation, and graft failure following the use of these flaps.
Materials and Methods
Following approval from our Institutional Review Board, we retrospectively reviewed the medical records of patients undergoing a free composite SALR flap (n = 5) for the treatment of a severe open tibia fracture within 1 month of injury. All patients sustained open injuries classified as IIIB on the Gustilo-Anderson scale.10 Medical records were examined for the mechanism of injury (MOI), injury severity score (ISS), time from injury to free tissue transfer, medical comorbidities, surgical complications, and time to radiographic and clinical union. Radiographic union was determined by the presence of bridging bone on 3 of 4 of cortices on plain film radiographs.
All patients were male (n = 5), with a mean age of 25 years (range, 19-30 years) at the time of injury (Table). The MOI included motorcycle collisions (n = 2), pedestrian struck by car (n = 1), motor vehicle collisions (n = 1), and direct blow to the leg (n = 1). The mean ISS of the cohort was 18 (range, 10-34) (Table). On average, patients underwent free tissue transfer within 1 week (range, 3 days to 2 weeks) from the time of injury. Patients in this cohort were followed clinically for a mean of 4 years (range, 1-6 years) after surgery. Patients were non-weight-bearing for an average of 5 months (range, 4-6 months) following their reconstructions.
All flaps survived. The mean time to radiographic and clinical union was 7 months (range, 6-9 months). Two patients underwent reoperation. One patient underwent a bone grafting procedure for a delayed union at 6 months postoperative, and 1 patient underwent irrigation and débridement of superficial soft tissue infection. Donor site complications occurred in 2 patients, including chronic rib pain (n = 1) and a pleural effusion requiring drainage (n = 1). At the last follow-up, all ribs had incorporated, and all patients were weight-bearing as tolerated on the limb.
A 22-year-old male smoker was transferred to our facility after a motor vehicle accident with bilateral tibia fractures, 1 closed and 1 open with significant bone loss (Figures 1A, 1B). He had initially been placed in an external fixator and transferred to our facility. A preoperative computed tomography angiogram was obtained to determine patency of recipient vessels.
The patient is placed in the lateral decubitus position during the procedure. A 2-team approach is used for dissection of the flap and preparation of recipient vessels to decrease operative time. A J-shaped incision is started on the chest at the mid-axillary line and extended just over the fifth and sixth rib. The incision can be made to fall into the intermammary crease in a woman to hide the scar. The dissection begins by exposing the anterior border of the latissimus muscle (Figure 2A). Next, the latissimus is dissected to reveal the thoracodorsal vessels (Figure 2B). At this level, the thoracodorsal vessel can be traced into the axilla. The branch going into the fifth, sixth, and lower slips of the serratus are dissected. The long thoracic nerve and the thoracodorsal nerve are preserved during the dissection (Figure 2C). The fifth, sixth, and seventh slips of the serratus are preferentially included in the dissection while leaving the most superior slips of the serratus to preserve scapular stability. Dissection begins by identifying 2 adjacent rib sections of the fifth and sixth or sixth and seventh ribs. The defect in the lower extremity determines the length of rib harvested. The serratus slips are then divided anteriorly over the chest wall. The dissection is extended to the intercostal spaces of the fourth and fifth ribs. The supraperiosteal dissection is performed at the anterior margin of the rib (Figure 2D). The intercostal vessels to the fourth rib are dissected free to preserve vascularity and sensation to the nipple areola complex. The ribs are dissected back at the level of the fifth rib superiorly and the distal aspect of the sixth rib, while being careful to preserve the intercostal vessels with the sixth rib to preserve the periosteal blood supply. The intercostal vessels are ligated as the length of rib is dissected posteriorly. Here the serratus muscle is left intact with the periosteum and now is divided posteriorly. Dissection is then performed around the serratus branch of the thoracodorsal vessels and these are dissected back to the main thoracodorsal trunk (Figure 3A). The small branches of the long thoracic nerve are preserved proximally to maintain the innervation to more proximal segments of the serratus. The serratus is then lifted off the chest wall with the underlying rib and a segment of the intercostal muscle (Figure 3B). The defect in the chest wall can then be reconstructed with synthetic mesh or decellularized dermis (Figure 3C). The parietal pleura is not violated in most dissections; however, if it is, a temporary chest tube or red rubber catheter can be placed within the thorax and allowed to water seal for 24 hours. The flap may be taken with a portion or all of the latissimus if there is a requirement for significant soft tissue reconstruction. The latissimus, serratus, and rib are all maintained on the thoracodorsal vessels, which are dissected to the level of the axillae. The thoracodorsal vessels are divided once adequate length has been achieved and the flap is transferred down to the lower extremity where the anastomosis is performed preferentially in an end-to-side fashion to the anterior or posterior tibial vessels. Following the anastomosis, the ribs are secured to the defect in an onlay fashion using compression screws. A washer is used in addition to the screw to allow for compression of the graft against the defect. A small partial greenstick fracture can be created over the curved aspect of the convex surface of the rib to enable the rib to straighten more effectively (Figure 4A). Small wedges can be removed from the rib to create a straight bone segment if this is necessary because of the length of the defect. Finally, the donor site in the chest is closed in a layered fashion. The latissimus and serratus portions of the flap are then covered with a split-thickness skin graft once they are secured in the lower leg.
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).
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
There are several limitations to this study. The small sample size and retrospective nature of the study limits the amount of data we are able to collect from the medical record and places obvious constraints on the analysis. Although all these procedures were performed at 1 institution, multiple providers were involved in the reconstruction of these injuries, and there is no standard protocol for their treatment. Similarly, although other forms of extremity reconstruction were used during this time period, there was no standard protocol that could serve as a comparator for patients who underwent an SALR compared with other reconstructive procedures.
Overall, SALR grafts provide an excellent option for 1-stage reconstruction of severe, open lower extremity injuries. In this series we noted a 100% graft success rate with an acceptable complication profile.
This paper will be judged for the Resident Writer’s Award.