Review
Free functional muscle transfer for upper limb paralysis – A systematic review

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Abstract

Background

Functional restoration of upper limb paralysis represents a major reconstructive challenge. Free functional muscle transfer (FFMT) enables reanimation in patients with a lack of local donor tissues or delayed presentation. This systematic review summarises the evidence for FFMT in the reconstruction of upper limb paralysis.

Methods

A comprehensive search of MEDLINE and EMBASE was performed with a systematic review using methodology adapted from the Cochrane Handbook and the PRISMA statement. Data from included studies were compiled and narratively synthesised. Studies were assessed for risk of bias.

Results

A total of 1155 records were screened, with 39 observational studies of 904 patients included. The most common aetiology was brachial plexus injury (736, 81.4%). Mean time from injury to intervention was 26 months. Restoration of elbow flexion was the commonest reconstructive goal. The most common donor muscle was gracilis (91.5%). Reported outcomes were heterogeneous with patient-reported outcome measures (PROMs) available in only 7 of 39 studies. Nearly half of FFMTs had a post-operative MRC grade of <4 and 18.1% had an MRC <3. Mean flap failure rate was 3.6% (range 0–10.5%). All studies were at high risk of bias.

Conclusions

FFMT may be an effective surgical intervention for upper limb paralysis; however, the current evidence has significant shortcomings. There is no consensus regarding outcome measures nor is it possible to identify prognostic factors for its effectiveness. This review highlights a need for improved study design with pre-operative assessment, standardisation in outcome reporting, and the use of PROMs to determine the effectiveness of FFMT in upper limb paralysis.

Introduction

Paralysis of the upper limb is debilitating with severe functional, psychological, and socioeconomic impact1, 2. Whilst surgical intervention can offer cost-effective improvement in quality of life3, 4, reconstructive surgery is far from able to restore function to pre-injury status. Various surgical techniques including tendon, nerve, and free functional muscle transfer (FFMT) are available for reanimation of the upper limb. Intervention selection depends on factors including aetiology and functional impairment, injury to reconstruction time, availability of donor tissues, and the patient/clinician's shared decision-making regarding treatment priorities.5

The major benefits of FFMT over other available techniques include limited donor site morbidity without further compromising upper limb function and the lack of restriction regarding the timing of surgery post-injury. First described in canine studies in 19706 and human subjects for facial reanimation in 1976 7, FFMT has since been utilised for the treatment of upper limb paralysis.8, 9 It is a useful technique particularly for patients in whom the motor unit has become irreversibly denervated, and where there is no adequate local or regional donor tissue that can be sacrificed without unacceptable morbidity. It is often used following failed nerve transfers or in delayed reconstruction. However, the disadvantages of FFMT include complex planning and execution, as well as prolonged recovery and rehabilitation.10

There has been a recent uptake in the use of FFMT in upper limb paralysis.9 However, there is no consensus on clinical indication. Furthermore, functional outcomes and adverse events are poorly understood. The aim of this systematic review is to summarise and appraise the evidence for the effectiveness of FFMT to treat upper limb paralysis.

Section snippets

Methods

This review followed the Cochrane Handbook for Systematic Review of Interventions and was reported in accordance with the PRISMA statement and checklist.11 The protocol was developed prospectively, locally peer-reviewed, and registered in the PROSPERO database (CRD42019139184).12

Study selection

There were 1155 unique records identified through database searching and screening, with 79 passing to full-text review. Thirty-nine studies met the inclusion criteria (Fig. 1).16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54

Study characteristics

All studies were observational. There were 36 cohort studies and 3 case series (Table 1). Of the cohort studies, 15 studies offered a comparative analysis of 2 or more

Discussion

This systematic review aimed to evaluate the current evidence on the effectiveness of FFMT to reconstruct upper limb paralysis. We identified 39 observational studies. Nearly all studies concluded that FFMT is an effective intervention for upper limb paralysis. However, significant heterogeneity was found in terms of patient population, cause of paralysis, interventions, and outcome reporting. The duration of follow-up varied significantly within and across studies. Only 21 studies reported

Conclusions

FFMT may offer restoration of function and improved quality of life to patients with upper limb paralysis. However, there is currently limited evidence to demonstrate its efficacy in terms of functional and patient-reported outcomes. Although the procedure is technically feasible with a low flap failure rate, there remains a lack of understanding of its impact on patients in their functional context or how this procedure compares to alternative surgical interventions including nerve and tendon

Ethics statement

Not relevant as this is a systematic review.

Conflict of Interest statement

None.

Financial disclosure statement

No funding was directly received for this article. No authors have any relevant commercial associations. JCR Wormald is funded by the Royal College of Surgeons of England.

Acknowledgements

None

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    • Presented at: 31 Oct 2019 - British Society for Surgery of the Hand Autumn Scientific Meeting, Dublin, Ireland

    05 Dec 2020 - Military Section Colt Foundation Research & Innovation Meeting, Royal Society of Medicine, London, UK

    Author involvement: All authors contributed to the design of the project. NT conducted the literature search. Manuscripts were screened by AR and HC, conflicts were resolved by discussion between AR, HC, and JW. Analysis and manuscript preparation was conducted by all authors.

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    © 2021 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.