gms | German Medical Science

Severe hand injuries that lead to amputations and extensive soft tissue defects require treatment by a specialized hand and trauma center. Such injuries are associated with extensive reconstructive procedures that are applied to restore the function, form, and aesthetic of the hand or its parts. Reconstructive procedures, such as local or free flap surgery for reconstruction of soft tissue, osteosynthesis, tendon transfer, free functioning muscle transfer, arthrodesis, tenodesis and other corrective procedures, are performed to restore function and form. In addition to functional loss and emotional burden for the patient, severe hand injuries also result in high financial costs due to health care expenses and productivity loss [1].

For these reasons, extensive reconstructive surgery after severe hand injury and complex multi-fascicular plexus brachialis lesion might be reconsidered for patients who may benefit from early supply of modern bionic prosthesis. An alternative first-intent surgical approach using myoelectric prosthetic functional replacement may be superior to an extensive reconstructive surgical approach in terms of overall functional outcome, interval of rehabilitation and cost-effectiveness.

New bionic tools can enable good functional use of the hand with unmatched freedom and integration into daily activities. These technologies require the following key elements: a modular prosthetic limb, a neural interface with signal processing and control algorithms as well as tissue and virtual integration [2].

The system is based on electromyographic (EMG) signals applied through conscious control of a specific muscle, leading to an inducible surface potential on the skin created by the residual muscle. This technique was developed over the last two decades and is in current use. However, enabling multiple degrees of motion remains an important goal of this technology. In addition to local EMG surface sensors, wireless implantable myoelectric sensors (IMES) have been developed [3], [4], [5], extending the possible capabilities of EMG sources to control the device. This advance increases the number of signal sources and opens the possibility of amputee and prosthesis control from an entirely different muscular area [6]. Another modern surgical procedure is called targeted muscle reinnervation (TMR). When complex nerve trauma is present, TMR transfers otherwise functionless residual nerves to new muscle targets for reinnervation [7], [8], [9], [10]. Upon successful reinnervation, the muscle amplifies the nerve motor signal [9], [11] to allow control of the prosthetic. Importantly, Aszmann et al. presented the first combined technique using selective nerve and muscle transfers, elective amputation and prosthetic rehabilitation to regain hand function in patients with global brachial plexus injury with lower root avulsion [12].

Current reconstruction approaches often do not consider an initial preparation for bionic prosthetic treatment option. However, in light of the recent advances in bionic prosthetics, it may be time to reconsider reconstructive procedures after severe hand injury in context of temporary coverage and early add-on prosthetic supply. Utilizing bionic prosthetics may be less stressful for patients, yield better results and higher satisfaction, and be more cost efficient. To implement an initial surgical approach for bionic reconstructions, the technology has to become available in hospitals with a hand surgery focus. If these new technologies and the supportive research are overlooked, they are unlikely to be integrated into specialized centers. The purpose of this study was to determine the level of knowledge and awareness among clinicians about important advances in bionic limb replacement.

We performed a cross-sectional assessment of the current knowledge of bionic prosthesis supply from a representative sample of specialists, residents, and students in departments for plastic and hand surgery, plastic surgery only, orthopedics, and trauma and hand surgery in German university hospitals. In addition, clinicians’ and students’ self-perceived knowledge regarding surgical reconstruction options for severe hand injury and outcomes of plexus brachialis damage were evaluated. We included students in the assessment to evaluate the current teaching level in the field. Anonymous questionnaires were collected by email, telephone interview, and from submission within the hospital.

The questionnaire was divided into 10 parts consisting of 40 questions. Seven parts queried factual knowledge and three parts queried self-perception of knowledge and awareness of surgical reconstruction for complex hand trauma. Included in the latter parts were questions to ascertain whether patients with unsuccessful reconstruction and permanent loss of function may be considered qualified for amputation and bionic prosthetic supply [12], [13].

Questionnaire total scores were determined by summing true and false selected answers to the survey. We created seven knowledge sections and three self-evaluation questions. The knowledge evaluation included 5 to 7 answer possibilities while the self-evaluation consisted of 4 selection possibilities with one possible selection. Multiple answer selection was possible for the knowledge section. Each correct answer added +1 point to the total and each false answer added –1 point. Knowledge classification was stratified with the following grading system for the summation of true (+1) and false (–1) answers: grade 1 (100%–85%), grade 2 (84%–70%), grade 3 (69%–55%), grade 4 (54%–40%) and grade 5 (<40%). No prior investigations for validity and reliability exist for this compilation of questions. The questions and correct answers were based on current research and general information about bionic prosthesis supply. Regarding self-perception we only assessed and described the selected answers statistically.

Level of knowledge and self-perception regarding bionic prosthesis supply, surgical indication and preparation for bionic supply, and subjective perception of appropriateness of supplying bionic prosthesis after complex or multi-fascicular injuries were evaluated. A descriptive statistical calculation was done by defining mean value () ± standard deviation SD, p<0.05, relative frequency of selected answers and diagrammatic representation were performed using Microsoft Excel Version 15.14. A validation of the questionnaire was not done. Based on the described methods a response rate could not be defined.

In total, 105 questionnaires from 30 specialists, 35 residents and 40 students were returned for evaluation. Specialists in plastic and reconstructive surgery departments with an additional hand surgery focus attained the highest mean rate of correct survey answers, falling in grade 3 (= 67% ± SD 13%, n=9 specialists, p<0.05, Figure 1 [Fig. 1]). Other specialty departments displayed lower correct response rates (Figure 1 [Fig. 1] and Figure 2 [Fig. 2]). The mean rate of correct answers reached grade 3 for trauma surgery with hand surgery focus (=59% ± SD 17%, n=6 (p<0.05), grade 4 for plastic and reconstructive surgery departments without hand surgery (=42% ± SD 10%, n=10 (p<0.05), and grade 4 for orthopedics (=41% ± SD 6%, n=5 (p<0.05). Students attained the lowest correct answer rate regarding current developments and technological details (= 27% ± SD 10%, significance level p<0.05, 95% interval). Nevertheless, there is a persistent knowledge increase from student to resident to specialist (Figure 1 [Fig. 1] and Figure 2 [Fig. 2]). No department attained better results than grade 3. Self-perception, ability to assess surgical indication and ability to prepare for surgery were evaluated as insufficient. Additionally, the perception of the outcome of severe hand injuries and plexus brachialis lesions seem not to be satisfying and suggests a need to improve outcomes. Most survey responses indicated an insufficient ability to consult and supervise on patients for supply with bionic prosthesis (Figure 3 [Fig. 3]). Most responses suggested that specialists cannot undertake the decision for a surgical indication and perform operations needed to supply patients with modern bionic prosthesis (Figure 4 [Fig. 4]). The majority of specialists, residents and students have an insufficient perception regarding the outcome of complex hand trauma and multi-fascicular plexus brachialis damages (Figure 5 [Fig. 5]). Figure 6 [Fig. 6] shows excerpts from the German survey.

Severe hand and multi-fascicular plexus brachialis injuries lead to high economic and social costs. However, there are strict selection criteria and therapy algorithms for such injuries. The burdens of hand disability and negative aesthetic appearance are exacerbated by repetitive operations with hospitalization, extended total operation time, psychological stress, and phantom limb pain [14]. The infirmity also leads to substantial financial and personal burden [15], [16]. Further, the reconstructive surgeries have imperfect records of functional and aesthetic restoration and the long duration of nerve regeneration affects quality of life and employability. For example, free flap surgery or reconstruction of soft tissue are associated with immobility of the hand, long lasting reduced hand functionality and poor aesthetic outcomes as well as the need for repetitive reoperations.

An alternative to traditional surgery with the potential for better economic and social outcomes involves the use of bionic limb replacement. Selection criteria for bionic reconstruction and a bionic score have to be defined for initial injuries. A scoring system for mutilating hand injuries could predict functional recovery and outcome of initial bionic prosthetic supply based on early amputation and temporary coverage of defects to restore hand function with a bionic prosthesis [17]. For patients with plexus brachialis lesions, a strict algorithm for bionic prosthesis supply is available [12], [17], [18], [19]. Hruby et al. showed that bionic reconstruction improves overall quality of life, restores an intact self-image and reduces deafferentation pain for patients with complete brachial plexopathies without hand functions for years [20].

However, we have found that there is a lack of understanding about such procedures. The survey described herein shows that, within German university hospitals, no department reached a correct response score regarding awareness of this treatment option higher than 67%. Departments with a hand surgery focus completed the questionnaires more accurately than others, but the results still suggest that there is room for significant improvement. Moreover, specialists and residents feel they have insufficient knowledge to consult or supervise patients regarding bionic prosthetic supply and do not confidently understand surgical indications or procedures for the operations. One alternative explanation for the results is that the complexity of multi-answer selection questionnaires may lead to misunderstanding of the questions. On the other hand, current literature suggests that only a few departments are researching the topic, which may best explain the limited breadth of knowledge that the survey revealed.

Recent developments in bionic replacement aim to solve the core problems in prosthetic supply. One priority is to deliver natural sensations when grabbing or touching an object. Such sensory feedback will likely be achieved through nerve surgery and implementation of neural connections. The ability to restore motor function to manipulate objects is based on these somatosensory signals. Initial promising trials with artificial sensors for hand prostheses stimulate the median and ulnar nerves by using multichannel intra-fascicular electrodes. This approach allows sensing of stiffness and shape [21]. Additional integrated sensors on the fingertips allow sensory feedback for very fine motor skills. Recently, Collinger et al. reported an extensive reconstruction of limbs in a patient with tetraplegia by using neuro-prosthetic limbs to recover upper extremity functionality [22]. However, treatment with bionic prosthesis needs long preoperative evaluation and training to identify and to control different EMG signals. For deinnervated muscles with no EMG signal, surgical procedures are needed, such as neurotization [23]. This pre-bionic training and preparation is needed for an appropriate use of the prosthesis [12], [24]. Also postoperative treatment and adaption of the prosthesis is necessary.

However, there still remains a gap in tissue integration processes such as osseous integration and electrode implantation into muscles and nerves [4], [25]. Recent publications have outlined neuro-prosthetic systems in which sensory information is processed through direct nerve stimulation, which may serve to bridge the time between currently available systems and completion of novel advanced systems [21], [26], [27]. Continued work should improve techniques for prosthetic integration directly into biological tissue like bone, nerve and muscle. In the near future, the merging of stimulation and decoding prosthetic systems with human biology may transform the future of plastic and reconstructive surgery [11]. There is an enormous potential for these new reconstructive technologies not only to restore function, but also to enhance it. Such advances will involve developing immune-inactive substances for material surfaces with stable integration into human biological systems.

Implementation of these and other exciting developments will require that medical practitioners are informed about their options. Knowledge of current state-of-the-art technologies can still provide patient benefit. To improve the general awareness of modern bionic prosthetic replacement, more studies must focus on patients supplied with prosthesis and describe their positive functional outcome and financial benefits. Nevertheless, the data should be considered taking into account the undefined response rate and the lack of validation of the questionnaire.

Our investigation showed that there is inadequate knowledge and awareness among clinicians regarding modern bionic prosthesis. Modern research and development in the field of hand surgery may change surgical intent and treatment of severe hand injuries and irreversible plexus brachialis injuries affecting hand function. Early discussion and decision making by patients, surgeons and insurers regarding treatment options may greatly impact long-term social and economic outcomes. A bionic score is necessary to assess initial injury patterns and helping to decide whether to choose surgical reconstruction or initial bionic prosthetic supply after severe hand injury. This discussion should include presentation of the most current surgical techniques and prosthetic limb devices. It is therefore critical that the involved participants understand the breadth of choices available.

The authors declare that they have no competing interests.