14-year-old patient with left arm mass
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A 14-year-old patient with no significant past medical history presented with a 2-year history of a left arm mass. On exam, the patient was neurovascularly intact with full strength and intact sensation throughout her left upper extremity. There was a firm, semi-mobile mass located over the dorsal ulnar left forearm. The mass had a negative Tinel’s sign, and she had no palpable lymph nodes. MRI showed a heterogeneous mass on the dorsal ulnar left forearm, with indeterminate features, that was closely associated with the radius (Figure 1). Biopsy was consistent with low-grade fibromyxoid sarcoma. CT of the chest was negative for metastatic disease. Wide resection was planned without radiotherapy secondary to the patient’s age. In anticipation of the need for soft tissue and potential bony reconstruction, a CT angiogram of the bilateral lower extremities was obtained (Figure 2). Despite the patient having palpable dorsalis pedis and posterior tibial pulses, the angiogram revealed absence of the bilateral posterior tibial arteries.
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Bilateral peronea arteria magna (dominant peroneal arteries)
Preoperative CT angiogram identified bilateral dominant peroneal arteries (peronea magna) with absence of the posterior tibial arteries. Prior to these findings, a free vascularized fibula flap with skin paddle was considered for reconstruction of the potential bony and soft-tissue defect following wide resection. After identification of this vascular anomaly, the surgical plan changed to include a composite parascapular flap if bony and soft-tissue reconstruction was necessary.
The patient underwent wide local excision of a left dorsal forearm sarcoma with a periosteal dissection of the tumor (Figure 3). Intraoperative frozen margins along the periosteum were negative for tumor and, as such, no bone was resected. Following tumor resection there was an 8 cm by 15 cm soft-tissue defect. As no bone was needed, a free anterolateral thigh (ALT) flap was used for reconstruction. The patient had an uneventful postoperative course and was discharged 5 days after tumor resection. At the latest follow-up, there was no evidence of recurrence and the flap had healed.
Bony flap for reconstruction
The free vascularized fibula flap (FVF) is a commonly used bony flap for reconstructing segmental bone defects, which provides a long segment of bone with a reliable and long pedicle. In addition, it can be harvested as a composite flap to provide soft-tissue coverage in the setting of a combined bony and soft-tissue defect. With most of the blood supply to the foot provided by the anterior and posterior tibial arteries, sacrifice of the peroneal artery, which is the primary blood supply to the fibula and skin of the lateral leg, often does not lead to ischemic complications of the foot.
In rare cases of variations in arterial anatomy to the lower leg, harvest of the peroneal vessel for FVF can lead to compromise of the blood supply to the foot. Hypoplasia of the anterior or posterior tibial arteries leads to a dominant peroneal artery (peronea arteria magna). Variations in popliteal artery branching have been classified as type 3A (hypoplasia of the posterior tibial artery leading to a dominant peroneal artery which replaces the posterior tibial artery distally behind the medial malleolus); type 3B (anterior tibial artery is hypoplastic, leading to a dominant peroneal artery which replaces the dorsalis pedis artery distally); and type 3C (both anterior and posterior tibial arteries are hypoplastic, leading to a dominant peroneal artery which replaces the entire blood supply distally). As these variations can mimic intact distal pulses, these are often not identified without imaging of the vascular supply to the foot.
CT angiogram of vascular supply
Preoperative planning, including advanced imaging of the lower extremities, is essential to evaluate for any abnormalities that may affect a soft-tissue flap donor site. An uncommon vascular anomaly, such as peronea arteria magna, can lead to substantial ischemic complications if not preoperatively recognized. In the case presented, preoperative CT angiogram (CTA) was performed to verify the vascular supply to multiple flaps, including the fibula, which is when it was discovered the patient had a bilateral peronea arteria magna. To our knowledge, this has not previously been reported.
Often, a clinical exam alone is not sensitive enough to detect a peronea arteria magna anomaly because the peroneal artery can mimic the normal dorsalis pedis and/or posterior tibial artery pulses distally. Such anatomical variants, in which either the anterior or posterior tibial arteries are hypoplastic, occur in 7% to 12% of the population. Instances in which the peroneal artery is the only vascular supply to the foot occur in 0.2% to 5.3% of the population and are most often a unilateral phenomenon.
Although there is no standardized preoperative vascular imaging modality, no instance of ischemic complications to the foot has been reported when vascular studies are obtained prior to FVF. As screening for anatomic variations via clinical history, physical examination and even Doppler probe have been shown to have poor sensitivity, we recommend vascular imaging for preoperative vascular flap planning. Our preferred method is to use CTA when deciding whether to modify or abandon the FVF when anatomic variants are present. In addition, preoperative vascular planning has been shown to decrease flap dissection time, improve flap survival and decrease risk of injury to lower limb vasculature.
- References:
- Abou-Foul AK, et al. Br J Oral Maxillofac Surg. 2017;doi:10.1016/j.bjoms.2017.08.363.
- Betz LH, et al. Pediatr Radiol. 2009;doi:10. 1007/s00247-009-1253-2.
- Houdek MT, et al. Bone Joint J. 2017;doi:10. 1302/0301-620X.99B1.BJJ-2016-0160.R1.
- Kim D, et al. Ann Surg. 1989;doi:10.1097/ 00000658-198912000-00014.
- Young DM, et al. J Reconstr Microsurg. 1994; doi:10.1055/s-2007-1006596.
- For more information:
- Matthew T. Houdek, MD, and Elizabeth P. Wellings, MD, can be reached at Department of Orthopedic Surgery, Mayo Clinic.
- Steven L. Moran, MD, can be reached at Division of Plastic and Reconstructive Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. Houdek’s email: houdek.matthew@mayo.edu. Wellings’ email: wellings.elizabeth@mayo.edu. Moran’s email: moran.steven@mayo.edu.
- Edited by Joshua D. Johnson, MD, and Nicholas A. Trasolini, MD. Johnson is a chief resident in the department of orthopedic surgery at Mayo Clinic in Rochester, Minnesota. He will be a musculoskeletal oncology fellow at MD Anderson following residency. Trasolini is the administrative chief resident in the department of orthopedic surgery at Keck Medical Center of the University of Southern California and will be a sports medicine fellow at Rush University Medical Center following residency. For information on submitting Orthopedics Today Grand Rounds cases, please email: orthopedics@healio.com.
Disclosures: Houdek, Moran and Wellings report no relevant financial disclosures.