What is the Elbow Flexion Strength After Free Functional Gracilis Muscle Transfer for Adult Traumatic Complete Brachial Plexus Injuries?

Abstract

Background: Traumatic brachial plexus injuries (BPIs) in the nerve roots of C5 to T1 lead to the devastating loss of motor and sensory function in the upper extremity. Free functional gracilis muscle transfer (FFMT) is used to reconstruct elbow and shoulder function in adults with traumatic complete BPIs. The question is whether the gains in ROM and functionality for the patient outweigh the risks of such a large intervention to justify this surgery in these patients.

Questions/purposes: (1) After FFMT for adult traumatic complete BPI, what is the functional recovery in terms of elbow flexion, shoulder abduction, and wrist extension (ROM and muscle grade)? (2) Does the choice of distal insertion affect the functional recovery of the elbow, shoulder, and wrist? (3) Does the choice of nerve source affect elbow flexion and shoulder abduction recovery? (4) What factors are associated with less residual disability? (5) What proportion of flaps have necrosis and do not reinnervate?

Methods: We performed a retrospective observational study at Dr. Soetomo General Hospital in Surabaya, Indonesia. A total of 180 patients with traumatic BPIs were treated with FFMT between 2010 and 2020, performed by a senior orthopaedic hand surgeon with 14 years of experience in FFMT. We included patients with traumatic complete C5 to T1 BPIs who underwent a gracilis FFMT procedure. Indications were total avulsion injuries and delayed presentation (>6 months after trauma) or after failed primary nerve transfers (>12 months). Patients with less than 12 months of follow-up were excluded, leaving 130 patients eligible for this study. The median postoperative follow-up period was 47 months (interquartile range [IQR] 33 to 66 months). Most were men (86%; 112 of 130) who had motorcycle collisions (96%; 125 patients) and a median age of 23 years (IQR 19 to 34 years). Orthopaedic surgeons and residents measured joint function at the elbow (flexion), shoulder (abduction), and wrist (extension) in terms of British Medical Research Council (MRC) muscle strength scores and active ROM. A univariate analysis of variance test was used to evaluate these outcomes in terms of differences in distal attachment to the extensor carpi radialis brevis (ECRB), extensor digitorum communis and extensor pollicis longus (EDC/EPL), the flexor digitorum profundus and flexor pollicis longus (FDP/FPL), and the choice of a phrenic, accessory, or intercostal nerve source. We measured postoperative function with the DASH score and pain at rest with the VAS score. A multivariate linear regression analysis was performed to investigate what patient and injury factors were associated with less disability. Complications such as flap necrosis, innervation problems, infections, and reoperations were evaluated.

Results: The median elbow flexion muscle strength was 3 (IQR 3 to 4) and active ROM was 88° ± 46°. The median shoulder abduction grade was 3 (IQR 2 to 4) and active ROM was 62° ± 42°. However, the choice of distal insertion was not associated with differences in the median wrist extension strength (ECRB: 2 [IQR 0 to 3], EDC/EPL: 2 [IQR 0 to 3], FDP/FPL: 1 [IQR 0 to 2]; p = 0.44) or in ROM (ECRB: 21° ± 19°, EDC/EPL: 21° ± 14°, FDP/FPL: 13° ± 15°; p = 0.69). Furthermore, the choice of nerve source did not affect the mean ROM for elbow flexion (phrenic nerve: 87° ± 46°; accessory nerve: 106° ± 49°; intercostal nerves: 103° ± 50°; p = 0.55). No associations were found with less disability (lower DASH scores): young age (coefficient = 0.28; 95% CI -0.22 to 0.79; p = 0.27), being a woman (coefficient = -9.4; 95% CI -24 to 5.3; p = 0.20), and more postoperative months (coefficient = 0.02; 95% CI -0.01 to 0.05]; p = 0.13). The mean postoperative VAS score for pain at rest was 3 ± 2. Flap necrosis occurred in 5% (seven of 130) of all patients, and failed innervation of the gracilis muscle occurred in 4% (five patients).

Conclusion: FFMT achieves ROM with fair-to-good muscle power of elbow flexion, shoulder abduction, and overall function for the patient, but does not achieve good wrist function. Meticulous microsurgical skills and extensive rehabilitation training are needed to maximize the result of FFMT. Further technical developments in distal attachment and additional nerve procedures will pave the way for reconstructing a functional limb in patients with a flail upper extremity.

Level of evidence: Level III, therapeutic study.

Fig. 1

This flowchart shows all patients who had surgical treatment for brachial plexus injury between 2010 and 2020 at Dr. Soetomo General Hospital; FFMT = free functional muscle transfer.

Fig. 2

These photographs show harvest of the gracillis muscle flap. (A) The gracilis was approached through three small incisions: a 3-cm longitudinal incision at the pes anserine, a 5-cm transverse incision in the medial aspect of the distal thigh, and a 15-cm longitudinal incision in the medial thigh. (B) The adductor longus was retracted anteriorly to cut the gracilis origin at the inferior ramus of the pubis. (C) We identified the anterior branch of the obturator nerve, medial circumflex artery, and two concomitant veins. (D) The gracilis was dissected from the thigh, with a full-length gracilis muscle (44 cm) and tendon (6 cm).

Fig. 3

This figure shows distal attachment of the gracilis tendon to the extensor carpi radialis brevis for wrist stabilization, performed in 84% (110 of 130) of patients. The gracilis flap was proximally attached to the distal one-third of the clavicle with a subcutaneous tunnel on the anteromedial aspect of the arm along the medial distal humerus.

Fig. 4

This figure shows three boxplots with postoperative ROM for elbow flexion (n = 130 patients), shoulder abduction (n = 130), and wrist extension (n = 94) after FFMT in patients with total BPIs. The middle line shows the median, the borders of the boxplots show the interquartile range, and the outer lines show the minimum and maximum ROM values; FFMT = free functional muscle transfer; BPI = brachial plexus injury.

Fig. 5

This bar chart shows the postoperative MRC strength for (A) elbow flexion, (B) shoulder abduction, and (C) wrist extension after FFMT in 130 patients with total BPIs. The number of patients with the same MRC outcome is also shown per bar; MRC = Medical Research Council; FFMT = free functional muscle transfer; BPI = brachial plexus injury.

Fig. 6

These graphs show the postoperative MRC strength for (A) elbow flexion, (B) shoulder abduction, and (C) wrist extension after FFMT in 130 patients with total BPIs, stratified for the difference in time between injury and surgery: patients with early intervention (≤ 6 months) (light blue), patients with delayed intervention (7 to 12 months) (medium blue), and patients with late intervention (> 12 months) (dark blue). The number of patients with the same MRC outcome is also shown; MRC = Medical Research Council; FFMT = free functional muscle transfer; BPI = brachial plexus injury.