Tendon transfer for the restoration of upper limb function after a cervical spinal cord injury

The Surgical Restoration of Arm and Hand Function in Tetraplegic Patients

BACKGROUND

There are approximately 140 000 people in Germany with spinal cord injury, with approximately 2400 new patients each year. Cervical spinal cord injuries cause, to varying degrees, weakness and impairment of everyday activities of the limbs (tetraparesis, tetraplegia).

METHODS

This review is based on relevant publications retrieved by a selective search of the literature.

RESULTS

From among 330 initially screened publications, 40 were included and analyzed. Muscle and tendon transfers, tenodeses, and joint stabilizations yielded reliable functional improvement of the upper limb. Tendon transfers improved the strength of elbow extension from M0 to an average of M3.3 (BMRC) and grip strength to approximately 2 kg. In the long term, 17-20% of strength is lost after active tendon transfers and slightly more after passive ones. Nerve transfers improved strength to M3 or M4 in over 80% of cases, with the best results overall in patients under 25 years of age who underwent early surgery (within 6 months of the accident). Combined procedures in a single operation have been found to be advantageous compared to the traditional multistep approach. Nerve transfers from intact fascicles at segmental levels above that of the spinal cord lesion have been found to be a valuable addition to the established varieties of muscle and tendon transfer. The reported long-term patient satisfaction is generally high.

CONCLUSION

Modern techniques of hand surgery can help suitably selected tetraparetic and tetraplegic patients regain the use of their upper limbs. Competent interdisciplinary counseling about these surgical options should be offered as early as possible to all affected persons as an integral part of their treatment plan.

Upper Limb Nerve Transfer Surgery in Patients With Tetraplegia

IMPORTANCE

Cervical spinal cord injury (SCI) causes devastating loss of upper extremity function and independence. Nerve transfers are a promising approach to reanimate upper limbs; however, there remains a paucity of high-quality evidence supporting a clinical benefit for patients with tetraplegia.

OBJECTIVE

To evaluate the clinical utility of nerve transfers for reanimation of upper limb function in tetraplegia.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective case series, adults with cervical SCI and upper extremity paralysis whose recovery plateaued were enrolled between September 1, 2015, and January 31, 2019. Data analysis was performed from August 2021 to February 2022.

INTERVENTIONS

Nerve transfers to reanimate upper extremity motor function with target reinnervation of elbow extension and hand grasp, pinch, and/or release.

MAIN OUTCOMES AND MEASURES

The primary outcome was motor strength measured by Medical Research Council (MRC) grades 0 to 5. Secondary outcomes included Sollerman Hand Function Test (SHFT); Michigan Hand Outcome Questionnaire (MHQ); Disabilities of Arm, Shoulder, and Hand (DASH); and 36-Item Short Form Health Survey (SF-36) physical component summary (PCS) and mental component summary (MCS) scores. Outcomes were assessed up to 48 months postoperatively.

RESULTS

Twenty-two patients with tetraplegia (median age, 36 years [range, 18-76 years]; 21 male [95%]) underwent 60 nerve transfers on 35 upper limbs at a median time of 21 months (range, 6-142 months) after SCI. At final follow-up, upper limb motor strength improved significantly: median MRC grades were 3 (IQR, 2.5-4; P = .01) for triceps, with 70% of upper limbs gaining an MRC grade of 3 or higher for elbow extension; 4 (IQR, 2-4; P < .001) for finger extensors, with 79% of hands gaining an MRC grade of 3 or higher for finger extension; and 2 (IQR, 1-3; P < .001) for finger flexors, with 52% of hands gaining an MRC grade of 3 or higher for finger flexion. The secondary outcomes of SHFT, MHQ, DASH, and SF36-PCS scores improved beyond the established minimal clinically important difference. Both early (<12 months) and delayed (≥12 months) nerve transfers after SCI achieved comparable motor outcomes. Continual improvement in motor strength was observed in the finger flexors and extensors across the entire duration of follow-up.

CONCLUSIONS AND RELEVANCE

In this prospective case series, nerve transfer surgery was associated with improvement of upper limb motor strength and functional independence in patients with tetraplegia. Nerve transfer is a promising intervention feasible in both subacute and chronic SCI.

Hand Reconstruction in Children with Spinal Cord Injury

Comprehensive programs for children who sustain traumatic spinal cord injury should incorporate optimizing hand and upper extremity function along with the other traditional pillars of rehabilitation. Children's smaller anatomy, open growth plates, and future skeletal growth, combined with the age-related psychosocial impact of these injuries, require protocols suited to these age-related issues. There is a role for surgical reconstruction, as is the case for adults with traumatic tetraplegia, and surgical outcomes are equally beneficial and long lasting. Strict adherence to surgical indications, and surgical strategies and protocols that incorporate their age-related challenges, are the keys to successful management.

Considerations in the Management of Upper Extremity Spasticity

Spasticity is a movement disorder characterized by a velocity-dependent increase in muscle tone and a hyperexcitable stretch reflex. Common causes of spasticity include cerebral palsy, spinal cord injury, and stroke. Surgical treatment plans for spasticity must be highly individualized and based on the characteristics of patients and the spasticity in order to maximize functional gains. Candidates for surgery must be carefully selected. In this article, the authors review the pathophysiology of spasticity and discuss general considerations for surgical management with an emphasis on patient factors and spasticity characteristics. Specific considerations for the common causes of spasticity are presented.

Biceps-to-triceps transfer for elbow extension in persons with tetraplegia

PURPOSE

Restoration of elbow extension via tendon transfer is an integral part of upper extremity surgical reconstruction in persons with tetraplegia. The purpose of this investigation was to assess patient satisfaction and elbow extension strength after biceps-to-triceps transfers.

METHODS

This is a retrospective chart review of biceps-to-triceps transfers in patients with spinal cord injury. Forty-five patients (77 arms) with spinal cord injury underwent biceps-to-triceps transfer. A total of 40 patients (68 arms) were available for follow-up. The average age at surgery was 17.3 years (range, 6.4-21.7 y).The biceps tendon was transferred around the medial aspect of the arm. The preoperative elbow extension strength was 0/5 (54 arms), 1/5 (10 arms), or 2/5 (4 arms). We also used the Canadian Occupational Performance Measure to measure patient-perceived outcome in a subset of 8 subjects.

RESULTS

Stringent manual muscle testing (MMT) for elbow extension revealed a statistically significant increase in muscle strength after surgery (p < .001). Forty-two arms were able to extend completely against gravity (MMT 3/5 or greater). Nine arms had a mild extension lag against gravity (MMT of 3/5). Therefore, 75% (51/68) of arms were able to function overhead. Seventeen arms had MMT scores less than 3/5. The top 5 goals of the 8 patients with completed preoperative and postoperative Canadian Occupational Performance Measure results were analyzed. After transfer, all 8 patients reported improved performance of and/or satisfaction with at least one goal. Performance and satisfaction were greatly improved (at least 4 points) for activities of living such as dressing, grooming, reaching for objects, recreational activities, wheelchair propulsion, and transfers.

CONCLUSIONS

Based on these results, we believe the biceps-to-triceps transfer is a reliable technique for restoration of elbow extension in persons with tetraplegia. Overhead function is obtainable in most cases with careful surgical technique and meticulous postoperative therapy.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Involuntary, electrically excitable nerve transfer for denervation: results from an animal model

PURPOSE

The purpose of this study was to evaluate the efficacy of "paralyzed" nerve transfer (ie, transfer of an involuntary, nondegenerated, electrically excitable nerve onto an involuntary, degenerated, non-electrically excitable nerve) and functional electrical stimulation for reinnervation. We hypothesized that lower motor neuron cell body continuity with the motor cortex, via intact upper motor neurons, is not necessary for reinnervation of the extremities.

METHODS

Fischer 344 rats had lower thoracic spinal cord injury (SCI) followed by unilateral tibial nerve transection and delayed peroneal ("paralyzed") to tibial nerve transfer (group A) or primary neurorrhaphy (group B). Control groups had SCI and a unilateral hindlimb incision and nerve exposure only (group C) or a unilateral hindlimb disection and transection of both the tibial and peroneal nerves (group D). Three months after surgery, the proximal peroneal (group A) or proximal tibial (groups B, C, and D) nerves were electrically stimulated in vivo, and gastrocnemius force production was measured on both the operative and nonoperative hindlimbs. In addition, the distal tibial nerves from both the experimental and control-side hindlimbs were sectioned and stained with anti-neurofilament protein to determine total axon counts.

RESULTS

Mean gastrocnemius force return and mean axonal regeneration was 47% and 51%, respectively, for group A animals (n = 9), 68% and 73% for group B animals (n = 4), 97% and 99% for group C animals (n = 4), and 0 and 2% for group D animals (n = 4). A 1-way analysis of variance for independent samples yielded significant differences between groups A, B, and C for gastrocnemius force return and between all groups for axonal regeneration.

CONCLUSIONS

Paralyzed nerve transfer produces a mean of approximately 50% return of gastrocnemius force and axonal regeneration. Paralyzed nerve transfer combined with functional electrical stimulation is a viable method for reanimating denervated motor units in the setting of SCI.

Reconstruction of elbow extension

The loss of elbow extension power is particularly disabling for the nonambulatory patient. Reconstruction of elbow extension can be performed by a deltoid to triceps transfer or by a biceps to triceps transfer provides the most satisfying reconstruction for patients. Although the overall time for rehabilitation can be lengthy, the functional gain is substantial, predictable, and easily appreciated by the patient. Furthermore, the risks to residual preoperative function are practically nil.

Quantifying the passive extensibility of the flexor pollicis longus muscle in people with tetraplegia

STUDY DESIGN

Repeat measures design.

OBJECTIVE

The purpose of this study was firstly, to describe a simple clinical tool that can be used to measure the extensibility of the flexor pollicis longus (FPL) muscle; secondly, to test its reliability; and thirdly, to attain some 'normative' data of the extensibility of the FPL muscle in a representative sample of people with tetraplegia.

SETTING

A spinal cord injury unit in Sydney.

SUBJECTS

A total of 37 people (62 hands) with C4-C7 tetraplegia.

MAIN OUTCOME MEASURES

Angle of the carpometacarpal (CMC) joint of the thumb was measured in all subjects with the application of a series of thumb extensor torques. A device specifically designed for this purpose was used to standardize the torque and objectively quantify the CMC joint angle. In addition, repeat measurements were taken 3-5 days later in one subgroup of 13 subjects (one hand per subject) and 3 months later in another subgroup of 13 subjects (one hand per subject).

ANALYSIS

Intraclass correlation coefficients and percent close agreement scores were derived to quantify the 3-5 days and 3-month reliability between repeat measurements.

RESULTS

The median CMC angle of the thumb with the application of a 0.044 Nm torque was 63 degrees (range, 20-93 degrees). The intraclass correlation coefficients with the application of a 0.044 Nm torque were 0.88 (95% CI, 0.65-0.96) for measurements taken 3-5 days apart, and 0.90 (95% CI, 0.67-0.97) for measurements taken 3 months apart.

CONCLUSION

This study describes a simple and reliable way of measuring the extensibility of the FPL muscle in people with tetraplegia. This assessment tool and the 'normative' data provided in this study can be used to further investigate the contribution of the passive mechanical properties of the FPL muscle to hand function of people with C6 and C7 tetraplegia.

Analyse critique des modalités d’évaluation des résultats de la chirurgie fonctionnelle du membre supérieur tétraplégique. Revue de la littérature sur les 50 dernières années

OBJECTIVE

To study the methods of assessment of upper limb functional surgery in the literature.

METHODS

The literature review relating to the years 1950-2002 was carried out with three data bases: Medline, Pascal, Embase. This review also involved a thorough study of non-indexed references.

RESULTS

Although many instruments or tests are used to assess outcome after surgery, their reliability, validity and responsiveness have not been adequately proven. Methodology appears to be the major failing of the various scales used to assess these patients. The conceptual models underlying the evaluation are all too often unspecified. There is a lack of pertinence of the selected tasks for tetraplegics. There is limited documentation of the guiding framework or conceptualisation. Furthermore, the process of item selection is often unknown. Scales or instruments are also deemed to be too insensitive to document the small but meaningful functional gains made by tetraplegics after functional surgery.

CONCLUSION

To answer the need for a specific assessment tool for tetraplegics who undergo functional surgery, we have developed a national, multicenter, prospective and longitudinal study based on two concepts: the first concept is related to Life Habits that are the activities of daily living and social roles recognised by the socio-cultural context of a person according to age, sex and social and personal identity. They include activities that should be accomplished on a daily basis (nutrition, fitness, personal care, communication, mobility, etc.). Life Habits presenting a significant level of disruption can create handicap situations. The second concept is in relation with Motor Capacities that correspond to the abilities of a patient to perform basic and functional tasks regardless of contextual factors (environmental and personal factors).

Prospective evaluation of biceps to triceps and deltoid to triceps for elbow extension in tetraplegia

PURPOSE

The purpose of this study was to evaluate and compare the deltoid to triceps and biceps to triceps transfers for restoration of elbow extension in young persons with tetraplegia.

METHODS

This was a prospective randomized study. Sixteen arms of 9 subjects between 8 and 20 years of age with cervical-level spinal cord injuries were assigned randomly to undergo either a deltoid to triceps transfer or a biceps to triceps transfer. All arms were followed-up prospectively for at least 2 years after surgery.

RESULTS

Elbow extension was restored in 8 arms via the deltoid and in 8 arms via the biceps transfers. At the 24-month follow-up evaluation 7 of the 8 biceps transfers produced antigravity strength (grade 3 or better); in contrast only one arm with the deltoid transfer was able to extend against gravity. There was a considerable but subclinical loss (no subject appreciated any functional deficit) of elbow flexion torque after both transfers. Three months after surgery the deltoid group showed a 51% loss of elbow flexion torque and the biceps group showed a 52% loss of elbow flexion torque. By 24 months after surgery both groups improved but still showed a loss of flexion torque (deltoid 32%, biceps 47%). After gaining elbow extension the subjects in both groups rated the performance of most activities of daily living (ADL) and all self-selected activities as better, as measured on the Modified University of Minnesota Tendon Transfer Functional Improvement Questionnaire and the Canadian Occupational Performance Measure, respectively. Likewise all subjects were more satisfied with performance of their goals after undergoing elbow extension reconstruction.

CONCLUSIONS

This study showed the benefits of restoring elbow extension in persons with tetraplegia and provided support for the biceps transfer as an alternative to the deltoid to triceps transfer in individuals with good brachialis and supinator strength.

Improved kinematics of unrestrained arm raising in C5-C6 tetraplegic subjects after deltoid-to-triceps transfer

STUDY DESIGN

Prospective comparative study.

OBJECTIVE

To determine whether control of upper limb joint synergy during unrestrained arm raising involving shoulder and elbow flexion is modified by deltoid-to-triceps transfer.

SETTING

Rehabilitation unit for spinal cord injury patients, France.

METHODS

Five C6 subjects with C5-C6 tetraplegia sustained posterior deltoid-to-triceps transfer and were compared to a control group of 11 subjects. Kinematics of shoulder and elbow joints before, 6 month and 1 year after surgery, during straight-arm raising (SAR) in the plane of the scapula and hand-to-nape-of-neck movements (HNNMs) were explored. Motion was recorded with a six-camera Vicon motion analysis system and the data used to assess the coupling of elbow and shoulder flexion velocities (EFVs and SFVs) and extension velocities.

RESULTS

All subjects were initially assessed at 6.9 months (mean) postsurgery. Three of the upper limbs were assessed a second time (mean 17.9 months). The first assessment showed an increase in shoulder flexion amplitudes in tetraplegic subjects with presurgery shoulder flexion deficits. Peak SFVs and EFVs and extension velocities were slightly modified at the first postsurgery assessment and dramatically improved at the second assessment during both SAR and HNNM. Despite these increased velocities, joint coordination was only partially restored.

CONCLUSION

A restored elbow active extension improves the speed of elbow flexion. The additional improvement of shoulder motion emphasises the relation between joints in the control of arm movement.

[Functional surgery of upper limb in tetraplegics since 50 years]

OBJECTIVE

Development of upper limb functional surgery in tetraplegics in the last 50 years.

METHODS

The literature review relating to the years 1950-2002 was carried out with 3 data bases: Medline, Pascal, Embase. This review also involved a thorough study of non-indexed references.

RESULTS

A large number of surgical procedures are described. Two priorities are stressed by the authors: safety of these procedures and duration of postoperative immobilization.

CONCLUSION

This review of literature shows that the prospects for restoring upper limb function in tetraplegics are greater than ever, offering a larger number of patients the possibility to increase their independence in daily life. Functional surgery remains, nevertheless, demanding in terms of length of immobilization and presupposes requiring a multidisciplinary approach requiring rehabilitation teams to be up to date with surgical procedures.

The influence of elbow position on the range of motion of the wrist following transfer of the brachioradialis to the extensor carpi radialis brevis tendon

BACKGROUND

In patients who have an injury of the cervical spinal cord, the brachioradialis tendon may be transferred to the extensor carpi radialis brevis tendon to restore voluntary wrist extension. We hypothesized that the active range of motion of the wrist depends on the position of the elbow after this transfer because the brachioradialis changes length substantially during elbow flexion, which implies the maximum force that the muscle can produce varies with elbow position. The objectives of this study were to determine whether the position of the elbow influences the range of motion of the wrist following transfer of the brachioradialis to the extensor carpi radialis brevis tendon and to evaluate the effect of surgical tensioning.

METHODS

The range of motion of eight wrists was assessed after brachioradialis transfer. Two positions of the elbow were tested, the passive limit of elbow extension and 120 degrees of flexion. The range of motion of the wrist was also simulated with use of a biomechanical model. Using the model, we compared the active range of motion of the wrist, with the elbow at 0 degrees and 120 degrees of flexion, following three different approaches to surgical tensioning. The simulations were also repeated to evaluate how muscle strength influences outcomes.

RESULTS

Wrist extension decreased and passive flexion increased when the elbow was flexed. Maximum wrist extension was significantly correlated with passive flexion in all subjects (r = 0.95 and p < 0.001 when the elbow was extended and r = 0.82 and p < 0.03 when the elbow was flexed). The biomechanical model suggested that tensioning the tendon transfer so that the fibers of the brachioradialis do not become excessively short when the elbow is flexed may improve outcomes. The simulations also revealed that it is more difficult to maintain a consistent wrist position with the elbow in different postures when a weaker muscle is transferred.

CONCLUSIONS

The model suggests that altering the surgical tension could improve wrist extension when the elbow is flexed. However, the ultimate result is sensitive to the strength of the brachioradialis.

Elbow extension

Reconstruction of elbow extension is an established treatment with a high degree of patient satisfaction. The D-T transfer is the most common method and has the advantage of inducing no serious complications; however, it necessitates a long period of healing and recovery. The Bi-T transfer is used much less frequently and, in the author's opinion, has few advantages compared with the D-T transfer. It is somewhat less time consuming to perform, and the rehabilitation period is a few weeks shorter. This method, however, has several drawbacks, including difficulties in learning to use the muscle as an extensor and a reduction of elbow flexion strength, which might result in a subjective functional loss. What is the best treatment for patients with a posterior deltoid that has a strength grade of 2 or 3: a D-T or Bi-T transfer or functional electrical stimulation? Today, this question is impossible to answer. The author is convinced that the optimal postoperative regimen for a reconstructed elbow extension has not been found yet.

Management of the paralyzed elbow in tetraplegia

The management of the paralytic conditions in tetraplegia requires understanding neural pathophysiology. A comprehensive rehabilitative and surgical plan requires a multidisciplinary approach. Prior to redistributing the muscle forces across the elbow, a supple osseo-articular platform must be created. The authors recommend PDT and BTT transfers and a FES neuroprosthesis. Future work in this field will advance the application of neuromodulation and its deployment in different neurophysiologic states.

Kinematic assessment of manual skill following functional hand surgery in tetraplegia

To determine whether surgical key grip reinforcement actually leads to a better movement ability we developed a procedure for the kinematic analysis of manual skill following hand surgery in tetraplegia. The functional results of surgery in 5 cases were examined by the kinematic analysis of drawing movements using an electronic pen and a digitizer under 3 conditions: with eyes open, with eyes closed, and while performing a concurrent arithmetic task. Movement velocity and dysfluency (ie, the number of velocity changes per centimeter) were measured before and at several moments after surgery during subsequent rehabilitation. Both movement velocity and dysfluency showed good stability across repeated trials and were consistently affected by visual deprivation. Movement velocity showed a 39% increment between the first and last assessment. Although grip strength increased in all patients, it was not associated with the change of movement velocity. These results suggest that other factors (eg, deep sensibility, cognition, muscle coordination) play a critical role in the ability to use improved grip force for controlling drawing movements and emphasize the value of a kinematic assessment besides measuring isolated grip force in the evaluation of functional hand surgery.

Moment arm and force-generating capacity of the extensor carpi ulnaris after transfer to the extensor carpi radialis brevis

Tendon transfers to the extensor carpi radialis brevis (ECRB) are often performed to augment wrist extension. This study was conducted to analyze how transfer of the extensor carpi ulnaris (ECU) to the ECRB affects the moment arms, force-generating capacity, and moment-generating capacity of the ECU over a range of wrist flexion-extension. A graphics-based computer model was developed from anatomic measurements of the muscle-tendon paths before and after transfer. This model calculates the lengths and moment arms of the muscles over a range of wrist flexion-extension and represents the muscles' force-generating characteristics from previous measurements of their physiologic cross-sectional areas, fiber lengths, and pennation angles. Analysis of the computer model revealed that the maximum isometric extension moment of the ECU at the neutral wrist position increased from 0.50 N-m to 1.72 N-m after transfer to the ECRB. The deviation moment shifted from 2.72 N-m ulnar deviation to 1.42 N-m radial deviation. The extension moment generated by the ECU varied more with wrist flexion angle after transfer due to its broadened operating range on the muscle force-length relationship. The simulations highlight the need for proper intraoperative tensioning of the ECU to maximize the force-generating potential of the transferred muscle over the functional range of motion.

Gaining independence in tetraplegia. Cleveland technique

Considerable independence can be achieved by four simple operations that can be done for patients with tetraplegia. Transfers for wrist extension were done 17 times. Posterior deltoid transfers were done 59 times. Opponens transfers were done 112 times. Transfers for finger flexion were done 88 times. Opponens and finger flexion transfers should be done at the same time. There were 22 other operations done. The patients with C6, C7, and C8 complete neurologic motor levels were almost as independent after their tendon transfers as paraplegics. They could transfer from a chair, insert a catheter, write, type, hold a book, take care of their toilet needs, bathe themselves, eat food and drink, dress themselves, and perform other activities of daily living. The few patients with a C5 neurologic level that was surgically treated for wrist extension acquired automatic grasp or used a wrist driven splint. A posterior deltoid transfer was not done on any of the patients with a C5 neurologic level but it is recommended now.

A comparison between control methods for implanted FES hand-grasp systems

Implanted neuroprostheses employing functional electrical stimulation (FES) provide grasp and release to individuals with tetraplegia. This paper describes and compares three methods of controlling the stimulated hand movement: shoulder position, wrist position and myoelectric activity from the wrist extensors. Three experienced neuroprosthesis users were evaluated with each of the control methods by performing a grasp release test (GRT). A significant improvement was found between each functional electrical stimulation (FES) method and tenodesis without FES. No significant difference in overall performance was found between the three FES methods of control. Each method of control demonstrated advantages and disadvantages which depend upon characteristics of the individual patient. Factors which must be considered are injury level, voluntary wrist strength, proximal upper limb strength, the level of cognition of the patient, hand-grasp characteristics, cosmeses, importance of using both arms, and personal preference. Due to the unique characteristics of each controller type, it is advantageous to have each type available for the FES patients to adapt the system to the needs and desires of the individual patient.

The outcome of tendon transfers for C6-spared quadriplegics

The purpose of this study was to review retrospectively and evaluate a uniform group of C6-spared quadriplegics who had similar surgical procedures. Eight patients undergoing 12 procedures were reviewed at an average of 3.8 years follow-up. There were three bilateral procedures. All patients had extensor carpi radialis longus to flexor digitorum profundus and brachioradialis to flexor pollicis longus transfers to improve grip strength and key pinch. All patients reported subjective improvements in quality of life, activities of daily living and patient-centred goals. There were six excellent and two good results. Objective improvements included mild improvements in key pinch and grip strength.

Peripheral nerve stimulation for restoration of motor function

This review paper discusses the use of electrical stimulation to restore function after upper motor neurone type of paralysis. It describes the basic physiology of electrical stimulation, the electrophysiology and biomaterials associated with using metal electrodes to deliver charge to living tissue, and also the adverse effects of stimulation. The central concepts of electrode applications, stimulus parameters, muscle fatigue, and stimulation control are covered. Next, a survey of clinical applications is made with focus on upper and lower limb applications. A concluding section mentions the current status of commercial products available for stimulation.

Implanted functional electrical stimulation hand system in adolescents with spinal injuries: an evaluation

OBJECTIVE

To study the utility and functional benefits of an implanted functional electrical stimulation (FES) system for hand grasp and release in adolescents with tetraplegia secondary to spinal cord injuries.

DESIGN

Intervention study with before-after trial measurement with each subject as his or her own control.

SETTING

Nonprofit pediatric orthopedic rehabilitation facility specializing in spinal cord injury.

PARTICIPANTS

A convenience sample of five adolescents between 16 and 18 years of age with C5 or C6 level tetraplegia at least 1 year after traumatic spinal cord injury. Key muscles for palmar and lateral grasp and release were excitable by electrical stimulation.

INTERVENTIONS

A multichannel stimulator/receiver and eight electrodes were surgically implanted to provide stimulated palmar and lateral grasp and release. In conjunction with implantation of the FES hand system, surgical reconstruction in the form of tendon transfers, tendon lengthenings and releases, and joint arthrodeses was performed to augment stimulated hand function. Rehabilitation of the tendon transfers and training in the use of the FES hand system were provided.

MAIN OUTCOME MEASURES

Measurements of pinch and grasp force, the Grasp and Release Test (GRT), and an assessment of six activities of daily living (ADL) were administered before implantation of the FES hand system and at regular follow-up intervals. Results of the stimulated response of individual muscles and surgical reconstruction were evaluated using standard and stimulated muscle testing techniques and standard assessment of joint range of motion. All subjects completed followup testing.

RESULTS

Lateral and palmar forces were significantly greater than baseline forces (p = .043). Heavy objects on the GRT could only be manipulated with FES, and FES increased the level of independence in 25 of 30 ADL comparisons (5 subjects, 6 activities) as compared to baseline. After training, FES was preferred in 21 of 30 comparisons over the typical means of task completion. Of the 40 electrodes implanted, 37 continue to provide excellent stimulated responses and all of the implanted stimulators have functioned without problems. The surgical reconstruction procedures greatly enhanced FES hand function by either expanding the workspace in which to utilize FES (deltoid to triceps transfer), stabilizing the wrist (brachioradialis to wrist extensor transfer), or stabilizing joints (intrinsic tenodesis transfer, FPL split transfer).

CONCLUSION

For five adolescents with tetraplegia, the combination of FES and surgical reconstruction provided active palmar and lateral grasp and release. Laboratory-based assessments demonstrated that the FES system increased pinch force, improved the manipulation of objects, and typically increased independence in six standard ADL as compared to pre-FES hand function. The study also showed that the five adolescents generally preferred FES for most of the ADL tested. Data on the benefits of the implanted FES hand system outside of the laboratory are needed to understand the full potential of FES.

Brachioradialis transfer for wrist extension in tetraplegic patients who have fifth-cervical-level neurological function

The brachioradialis tendon was transferred to the extensor carpi radialis longus and brevis tendons to restore active extension of the wrist in nine patients who had traumatic tetraplegia. The classification of neurological function was the fifth cervical level for all patients. The average time from the injury to the operation was six years (range, one to twenty years), and the average duration of follow-up was ten years (range, two to fifteen years). The evaluation of the patient included a determination of the preoperative and postoperative ranges of motion of the wrist, manual muscle-testing of the strength of the brachioradialis and the wrist extensors, a functional assessment of the ability to perform activities of daily living (eating, grooming, dressing, personal hygiene, and desktop activities [writing, typing, using a telephone, and so on]), and an assessment of functional independence. In addition, the result of the operation was evaluated subjectively by the patient. No patient had active extension of the wrist against gravity preoperatively. The strength of the wrist extensors improved postoperatively to a grade of good in six patients and to a grade of fair-plus in three. Function of the hand improved markedly in seven patients, and no patient had a loss of function. The patients had improvement in the ability to pick up objects, to feed and groom themselves, to tend to personal hygiene, to write and type, and to use a telephone.

Functional hand surgery following tetraplegia

Traumatic tetraplegia is an overwhelming injury often requiring permanent adaptations by patients and families. The greatest potential for improving the quality of life lies with rehabilitation and restoration of upper extremity function. Reconstructive hand surgery following tetraplegia is individualized based on functional level and can significantly improve hand function and quality of life. Careful selection and evaluation of surgical candidates in combination with an experienced surgeon and hand rehabilitation team are critical for a successful outcome.

Elbow extension using anterior deltoids and upper pectorals in spinal cord-injured subjects

OBJECTIVE

Surface electromyography was used to identify muscles active in isometric elbow extension in spinal cord-injured (SCI) patients.

DESIGN

Tetraplegic subjects participated in this cohort study aimed at identifying some of the muscles that are active during isometric elbow extension.

SETTING

Regional Spinal Cord Injury (SCI) Center.

PATIENTS

The patients had to have a C6 motor level on the right side (wrist extensor > or = 3/5) with 0/5 or 1/5 elbow extensor muscle power. Of 32 patients who could be contacted by telephone, 6 eventually were able to make it to the SCI center for testing.

MEASUREMENTS

The patients performed a series of isometric elbow extension contractions of 25%, 50%, and 75% of maximum voluntary contraction (MVC) as measured by a force transducer. Surface electromyography (EMG) of the right elbow extensor, anterior deltoid, and upper pectoral muscles was measured using the root mean square (rms) of the amplitude of the motor unit activity as the parameter of muscle activity. Statistical analyses were performed using a repeated analysis of variance (ANOVA) with Tukey post-hoc HSD for each percentage of MVC.

RESULTS

For each muscle tested, there was significantly (p < 0.05) greater rms activity for each percentage of MVC except between 50% and 75% MVC of the elbow extensor muscle. However, the elbow extensor muscle had minimal EMG activity when compared with the amplitude of the rms activity of the anterior deltoid and upper pectoral muscles for each percentage of MVC.

CONCLUSION

The results of the study suggest that the anterior deltoid and the upper pectoral muscles exert an isometric elbow extension force for C6 quadriplegic patients.

Rerouting of the biceps brachii for paralytic supination contracture of the forearm in tetraplegia due to trauma

Six tetraplegic patients (eight forearms) who had a supination contracture were evaluated after lengthening and rerouting of the biceps brachii. Preoperatively, the mean range of supination and pronation of the forearm was 85 and 14 degrees, respectively. Pronation increased a mean of 75 degrees without affecting the strength of flexion or the flexion-extension arc of motion of the elbow. The forearms that had a satisfactory result had a mean active range of supination of 69 degrees, while those that had a poor result had no active supination. The mean duration of follow-up was twenty-seven months (range, twelve to seventy-two months). The result was considered satisfactory for six limbs and unsatisfactory for two. Functional gains were made in the patients' ability to feed and groom themselves, in their ability to tend to personal hygiene, and in writing and typing skills when the dominant extremity was treated. The results were less predictable for the non-dominant extremity. The maximum gain in the range of motion occurred at three months and the maximum functional gain, by six months.

Functional neuromuscular stimulation: outcomes in young people with tetraplegia

Percutaneous intramuscular functional neuromuscular stimulation (FNS) systems were fitted to the forearms of five adolescents with tetraplegia in an effort to provide active grasp and release. Two assessments designed at Case Western Reserve University to evaluate functional outcomes of FNS in adults were employed. The common object test (COT) was used to assess hand function during five activities of daily living (ADLs): eating, drinking, writing, brushing teeth and applying toothpaste. A usage survey provided information on the frequency of FNS use in environments outside of the laboratory. In addition, interviews were employed using open-ended questions to gain a deeper understanding of the perceptions of FNS in the adolescents' own environments. Based on the COT results, each adolescent was able to perform ADLs with and without FNS. However, FNS allowed unilateral function so that the extremity without FNS was freed to assist in balance or participate in bilateral tasks. Also, FNS reduced the need for multiple devices, providing users with the potential to perform activities in a variety of environments without transporting adaptive equipment. Those who reported using FNS most often obtained hard-bound school books, held pens during classroom and homework assignments, engaged in leisure activities and performed hygiene tasks. FNS was also used as a means to communicate and socialize through hand gestures. Well-known factors that influence the independence of people with tetraplegia also appeared to affect FNS use.

Tendon transfers in patients with cervical spinal cord injury

Between 1983 and 1988, 32 patients with cervical spinal cord injuries underwent 124 upper limb tendon transfers during 85 procedures. Of the numerous surgical procedures that have been recommended for treatment of this condition, my experience indicates that the most successful are posterior deltoid-to-triceps transfer, restoration of finger flexion, and restoration of thumb opposition. Longitudinal incisions prove to be quite cosmetic.

Reconstruction of the upper extremity in tetraplegia: functional assessment, surgical procedures and rehabilitation

The results of 22 procedures (8 for elbow extension, 14 for hand rehabilitation) on the upper limb in tetraplegia are reported. To evaluate the effect of surgery an objective hand function test is presented. The few complications after surgery must be attributed to the material used.

Elbow extension in the C5 quadriplegic using functional neuromuscular stimulation

A system has been designed to provide overhead reach in C5/6 quadriplegic subjects using functional neuromuscular stimulation (FNS) for control of the triceps muscle. The system uses the position of the arm in space as the input command, relieving the user from having to supply a conscious command signal. By measuring the position of the arm, the magnitude of the gravitational and passive torques opposing elbow extension can be calculated. This torque is counteracted by electrical activation of the triceps muscle, with the appropriate stimulus parameters determined from the recruitment characteristics of each electrode. Sufficient stimulus is applied to produce full elbow extension. Intermediate elbow angles are achieved using voluntary elbow flexor torque to counteract the effects of the stimulation. System performance was tested in two subjects. Subjects were asked to reach targets with and without stimulation, with loads up to 500 g in the hand. Using the FNS system, subjects were able to successfully reach the target positions above the horizontal that were inaccessible without stimulation.

Implantable functional neuromuscular stimulation in the tetraplegic hand

Functional neuromuscular stimulation of the upper extremity provides manipulative capacity to persons with high level tetraplegia who have insufficient voluntary muscles available for tendon transfer surgery. We report an enhancement of the technique to include surgical implantation of a multichannel receiver-stimulator, sensory feedback stimulation, and tendon transfers. Tendon transfers were done with spastic, rather than voluntary motors employing standard surgical techniques. The system described has been operational for more than 1 1/2 years.

Intraoperative assessment of wrist extensor muscle force

Surgical restoration of hand grasp in the patient with spinal cord injury at the sixth cervical level often involves use of one of the two radial wrist extensors. Because the loss of the remaining wrist function would be devastating, it is important to establish techniques for quantitatively predicting postoperative function before tendon transection. An in situ method has been developed for determining muscle strength during tendon transfer surgery. Buckle transducers are placed on the tendons of the extensor carpi radialis brevis and longus for simultaneous measurement of strength of each individual muscle during voluntary and/or electrically stimulated extension of the wrist. The measured strength of the extensor carpi radialis brevis is examined to determine whether sufficient wrist extension torque would remain if the long wrist extensor is transferred. This technique allows accurate measurement of the force developed in any voluntarily activated muscle that has a long tendon of insertion.

A review of surgical rehabilitation of the upper limb in quadriplegia

The options for surgical reconstruction of the quadriplegic upper limb are clarified by a new international classification of each limb independently, based upon the lowest functioning key muscle and residual sensation. Surgical restoration of active elbow extension, of pinch, and of grasp is now an accepted part of rehabilitation. This additional function may be achieved by transfer of a non-essential muscle, by tenodesis, or occasionally by arthrodesis. The techniques available for each group of the new international classification are described.

The contributions of plastic surgery to care of the spinal cord injured patient

Plastic surgeons have contributed to the understanding of pressure sore pathophysiology and prophylaxis. Increasingly sophisticated surgical techniques such as myocutaneous or innervated flaps add to the reliability and durability of repairs. The majority of quadriplegics may benefit from surgical restoration of active elbow extension, lateral pinch and grasp. Prolonged postoperative care in bed or immobilisation of the upper limb demands that patients should understand fully all that the reconstructive procedure involves. The nature and importance of subsequent rehabilitation must be appreciated by the patient so that he will be motivated to achieve the best possible result. Functional electrical stimulation may find an increasing role in the years to come.

The brachioradialis: anatomy, properties, and value for tendon transfer in the tetraplegic

We have studied the brachioradialis muscle both physiologically and clinically for its suitability for tendon transfer in the tetraplegic. Intraoperative measurements have shown that the muscle is strong, provides excellent excursion, and is commonly available for transfer in the absence of other candidate muscles. The anatomic features that limit its use can be overcome during the operation. Postsurgical assessment of the muscle using electromyography and muscle-force measurement have shown that the muscle is voluntarily activated and provides strength for the intended function. Our experience with transfer of the brachioradialis to the hand of a tetraplegic patient has been highly positive.

Postoperative results of opponensplasty and flexor tendon transfer in patients with spinal cord injuries

Key pinch, palmar pinch, and grasp strength were evaluated after opponensplasty and flexor tendon transfer in 24 patients who had suffered cervical spinal cord injuries during a 17-year period. The patients had 57 tendon transfers: 35 opponensplasties and 22 flexor tendon transfers. The average follow-up was 4.2 years. The brachioradialis and pronator teres were the most frequently used motors for the opponensplasty and flexor tendon transfer. Key pinch strength averaged 1.47 kg (range of 0.13 to 4.70 kg). Grasp strength averaged 2.81 kg (range of trace to 10.0 kg). Palmar pinch was obtained in 45% of the extremities; the overall result was 1.04 kg (range of 0.20 to 3.00 kg). In general, patients with higher functional classifications achieved better results. We believe that intraoperative length-tension studies were an important factor in improving the results. The choice of muscle for opponensplasty or flexor transfer when two different adequate motors were available did not seem to affect the outcome of key pinch or grasp. We believe that tendon transfers are beneficial and should be considered in all patients with spinal cord injuries regardless of age at injury if at least 1 year has elapsed since injury and the patients are neurologically stable and have participated in a rehabilitation program.