Gracilis Free Flap Technique for Elbow Flexion Reconstruction

Brachial plexus injuries (BPI) can be devastating for patients, often resulting in notable physical, psychological, and socioeconomic distress¹. Violent accidents that torque the head away from the shoulder frequently damage the upper brachial plexus roots, with varying severity of damage to the lower roots¹. Patients having pan-plexus injuries typically present with a flail extremity, loss of sensory function, and generalized atrophy. To improve activities of daily living, the treatment of pan-plexus injuries focuses on restoring antigravity motion of the upper extremity, with elbow flexion being a high priority muscle group². Although nerve transfers are an excellent option, this treatment path is not always viable. In such cases, free functioning muscle transfers, especially gracilis transfers, have emerged as a primary reconstructive approach, with excellent outcomes in complete BPI lesions^2,3. In this video article, we present the exploration of a complex BPI in which the creation of a gracilis free flap is executed for elbow flexion reconstruction. We provide a comprehensive guide from markings, flap elevation, microsurgical technique, and inset, with educational operative pearls at every step.

The procedure involves harvesting the gracilis muscle as a free functioning muscle transfer. The gracilis, which will become a type-II muscle flap, is carefully dissected with its pedicle and nerve preserved. The muscle is then transferred to the upper extremity, where its proximal origin is anchored to the clavicle and its distal tendon is inserted into the biceps tendon with use of a Pulvertaft weave. Vascular anastomoses are performed utilizing branches of the thoracoacromial trunk and venous couplers under a microscope. The muscle is innervated with the spinal accessory nerve and tensioned to ensure optimal elbow flexion.

Surgical alternatives include nerve transfers (e.g., Oberlin transfer), tendon transfers, or other free muscle transfers (e.g., latissimus dorsi transfer). Nonsurgical alternatives include orthotic devices to compensate for elbow flexion loss, and physical therapy to maximize existing function.

Gracilis free flap transfer is a reliable option for restoring functional elbow flexion in patients with severe BPI when intra-plexal nerve donors are unavailable. Compared with nerve transfers or tendon transfers, gracilis free flap transfer offers consistent outcomes with greater than M3 muscle strength (with M3 indicating movement against gravity but not against resistance, and M4 indicating movement against both gravity and resistance)². Unlike orthotic devices, this technique provides active elbow flexion, critical for functional independence. The long tendon and reliable vascular pedicle make the gracilis ideal for this purpose.

Free flap gracilis muscle transfer for elbow flexion reconstruction has shown promising outcomes in patients with traumatic brachial plexus injuries. Armangil et al. reported that 68.8% of patients achieved M3 or M4 elbow flexion strength, with a median active range of motion of 75° (range, 30° to 100°), and significant improvements in postoperative DASH and SF-36 scores⁴. De Rezende et al. (2021) demonstrated that 61.9% of patients achieved M4 strength, with 95.2% achieving M2 or higher, and a mean active range of motion of 77° (range, 10° to 110°) across the total cohort⁵. These findings suggest that free gracilis muscle transfer provides reliable functional improvements, enabling meaningful elbow flexion restoration and enhancing quality of life.

Utilize Doppler ultrasound to confirm the location of a skin perforator over the gracilis to aid in postoperative monitoring.Preoperative markings are key. Mark the orientation of the gracilis muscle belly and pedicle preoperatively for efficient harvesting.The gracilis inserts distal to the knee, so extending the knee can help distinguish it from the adductor longus.Preserve all fascia over the gracilis muscle to optimize muscle gliding.Ensure proper resting tension during gracilis insertion to prevent over- or under-tightening, optimize function, and avoid complications like hyperextension or limited flexion.Position the elbow at 90° of flexion and the forearm in supination when tensioning.Make accommodation for any vessel size mismatch between the gracilis pedicle and recipient vessels to minimize complications.Confirm intraoperative vessel patency with use of Doppler flow checks after completing the anastomoses.Confirm nerve viability intraoperatively with use of nerve stimulation, ensuring a strong muscle contraction response.Secure the nerve repair without tension and with the appropriate coaptation in order to maximize reinnervation success.Utilize drains to avoid fluid collections that can create pressure on the pedicle.Place the gracilis tendon insertion precisely with use of the Pulvertaft weave technique, ensuring secure fixation and proper alignment with the biceps tendon.

BPI = brachial plexus injuryDASH = Disabilities of the Arm, Shoulder and HandDVT = deep vein thrombosisEMG = electromyographyFFMT = free functioning muscle transferFGMT = free gracilis muscle transferICN = intercostal nerve transferM3/M4 = muscle strength grade 3 or 4MCA = medial circumflex arteryMCN = musculocutaneous nerveNCS = nerve conduction studyPPX = prophylaxisSAN = spinal accessory nerveSF-36 = Short Form-36.