Bionic Upper Limb Reconstruction: A Valuable Alternative in Global Brachial Plexus Avulsion Injuries-A Case Series

Abstract

Global brachial plexopathies including multiple nerve root avulsions may result in complete upper limb paralysis despite surgical treatment. Bionic reconstruction, which includes the elective amputation of the functionless hand and its replacement with a mechatronic device, has been described for the transradial level. Here, we present for the first time that patients with global brachial plexus avulsion injuries and lack of biological shoulder and elbow function benefit from above-elbow amputation and prosthetic rehabilitation. Between 2012 and 2017, forty-five patients with global brachial plexus injuries approached our centre, of which nineteen (42.2%) were treated with bionic reconstruction. While fourteen patients were amputated at the transradial level, the entire upper limb was replaced with a prosthetic arm in a total of five patients. Global upper extremity function before and after bionic arm substitution was assessed using two objective hand function tests, the action research arm test (ARAT), and the Southampton hand assessment procedure (SHAP). Other outcome measures included the DASH questionnaire, VAS to assess deafferentation pain and the SF-36 health survey to evaluate changes in quality of life. Using a hybrid prosthetic arm mean ARAT scores improved from 0.6 ± 1.3 to 11.0 ± 6.7 (p = 0.042) and mean SHAP scores increased from 4.0 ± 3.7 to 13.8 ± 9.2 (p = 0.058). After prosthetic arm replacement mean DASH scores improved from 52.5 ± 9.4 to 31.2 ± 9.8 (p = 0.003). Deafferentation pain decreased from mean VAS 8.5 ± 1.0 to 6.7 ± 2.1 (p = 0.055), while the physical and mental component summary scale as part of the SF-36 health survey improved from 32.9 ± 6.4 to 40.4 ± 9.4 (p = 0.058) and 43.6 ± 8.9 to 57.3 ± 5.5 (p = 0.021), respectively. Bionic reconstruction can restore simple but robust arm and hand function in longstanding brachial plexus patients with lack of treatment alternatives.

Keywords: artificial limbs; bionics; brachial plexus injury; chronic pain; nerve root avulsion; prostheses and implants; prosthesis fitting.

Figure 1

Flowchart showing detailed reasons for exclusion of patients with a global brachial plexus injury from the study.

Figure 2

(A) Despite complete muscle atrophy in the patient’s forearm a fascicle group containing viable motor axons was identified in the median nerve with an intra-operative fast staining method screening for acetylcholine positivity. (B) A free functional muscle, i.e., the gracilis muscle from the patient′s leg, was transferred to the medial upper arm and its muscle nerve branch (the obturator nerve) was co-apted to the fascicle group previously tested positive for the presence of functional motor axons. (C) After successful nerve regeneration and elective amputation, the patient′s attempt to make a fist produced a reliable EMG signal detectable with transcutaneous electrodes placed over the muscle. (D) To improve future prosthetic handling and avoid excess length of the prosthetic limb, a humerus shortening osteotomy was performed upon amputation in the same patient.

Figure 3

Adaptation of the human anatomy to improve the biotechnological interface and the information transfer between man and machine as performed in Case No. 3. To preserve valuable EMG activity, (A) the biceps muscle was transferred to the infraclavicular fossa and (B), the triceps muscle was transferred to the infraspinatous fossa. (C) The patient now controls his prosthetic arm with a two-signal control (transferred biceps and triceps m.); co-contraction of both signals allows him to switch between the three degrees of freedoms (elbow flexion/extension, hand rotational unit, hand opening/closing).

Figure 4

After initial rehabilitation including surface EMG signal training a hybrid prosthetic arm is mounted onto the functionless plexus arm. The patient controls it with the EMG signals identified and trained previously. This allows a prediction of future prosthetic control. The results of the objective hand function tests using the hybrid arm are video-documented and need to be superior to original upper extremity function before elective amputation of the plexus arm may be considered.