An 18-month-old female presented with an extensile mass of the extensor compartment of her dominant forearm. Her lesion is known by magnetic resonance imaging (MRI) to abut but not involve the posterior interosseous nerve (PIN). There was no bony involvement, and the mass did not extend through the interosseous ligament into the volar compartment. Biopsy confirmed the suspected diagnosis of malignancy, revealing a grade II synovial sarcoma with X:18 translocation. There was no regional node involvement or metastasis by radiographic staging (stage IIA). The patient underwent a primary resection of the extensor carpi radialis brevis and longus, supinator, and a portion of the brachioradialis (Figure 45-1). The PIN was resected beyond the bifurcation of the radial nerve motor and sensory nerves.

The absence of muscle function in a hand or upper limb can be devastating. This can be due to trauma, nerve injuries, compartment syndromes, cancers, and congenital deficiencies. Free muscle transfer is performed when (1) there are no other viable reconstructive options available, such as a regional tendon transfer, and (2) both the recipient site and donor muscle have a reasonable chance of successful functional outcome. Many muscles have been used for functional free muscle transfer with variable success. The best donor muscle for free transfer to the upper limb is the gracilis. The latissimus dorsi, pectoralis major, serratus anterior, and rectus abdominis have been used with less success. Restoration of elbow flexion, finger flexion, and finger extension are the most common functional goals of free muscle surgery, and much less commonly free transfers to the deltoid and triceps. This is complex surgery. Whenever possible, simpler solutions, if available, should be pursued.1^,2

Free muscle transfer is also performed for coverage of upper limb major soft tissue deficiencies whenever other less complex treatments (skin grafts, regional or pedicle flaps) are not viable. This is most common after major trauma, oncologic resection, and chronic infection. The gracilis, latissimus dorsi, transverse rectus abdominis (TRAM), and serratus anterior muscles are the usual free musculocutaneous flaps used for coverage in the upper limb. Free tissue transfer surgery is best performed with an outstanding team. Simultaneous harvesting of the donor muscle and preparation of the recipient site lessens anesthesia time, surgeon fatigue, and the most likely patient complications. The optimal team consists of highly skilled nurses and/or midlevel providers, therapists, surgical subspecialists, and cooperative patients and families.

The prerequisites for free tissue transfers are a high level of familiarity with the anatomy and performance of these procedures as well as expert microsurgical and hand reconstructive skills. There are no green circle or blue square level procedures here, only black diamond and double black diamond level skill for all members of the team. The thinking and planning part of these procedures strains the
brain. The doing part is very hard (“Why do you think microsurgery is a four-letter word?”) and requires a large treasure chest of expert technical skills. The communicating and doctoring part is critical to your patient’s wellbeing and outcome. You need to build yourself and every member of your team up to an elite level if this is to be a part of your career. If not, find some outstanding professional colleagues to whom you can send these complex patients for the best care possible. And then help with the before and after care.

For functional free muscle transfers, a suitable donor nerve is essential to a positive outcome. One of the problems with a brachial plexus injury that has been treated with microsurgery is that there may not be adequate donor nerves for late reconstruction with a free muscle. If all reasonable ipsilateral donors were used in the initial microsurgical neural reconstruction, the only alternatives become the contralateral C7, contralateral pectoral, or ipsilateral phrenic. None of these are universally predictable and have been abandoned by most centers. Besides poor nerve surgery outcome with some avulsion injuries in adults, the dearth of donor nerves is one of the reasons that Doi advocated for early free gracilis transfer for elbow flexion and digital extension; the SAN could be used for neurotization without expending it in the initial nerve reconstruction. Similarly, the ICNs can be preserved for later reconstruction of digital flexion, elbow extension, and hand sensibility.25 The best donor nerves are the SAN, ICNs, and the AIN and PIN for elbow and finger function. The gracilis is the best muscle for upper limb functional transfers. It is expendable; has predictable nerve and blood supply; and contours well for elbow flexion, digital flexion, and digital extension. It can be harvested with a skin paddle or covered with a split-thickness skin graft. Its functional excursion usually results in an improved limb.