Use of Thermoplastic Rings Following Venting of Flexor Tendon Pulleys: A Biomechanical Analysis.

PURPOSE: Normal digital flexion relies on flexor tendon pulleys to convert linear muscular force to angular digital motion. However, there is a growing trend to vent them partially during flexor tendon repair. The objective of this study was to examine the effects of a thermoplastic ring, acting as an external pulley, on flexor tendon biomechanics and finger range of motion (ROM) after pulley venting. METHODS: We tested 15 cadaveric digits using an in vitro active finger motion simulator. We measured loads induced by flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) as well as joint ROM with sequential sectioning of the A2, A3, and A4 pulleys compared with an intact pulley condition. At each stage, external thermoplastic pulley rings were applied snugly over the proximal and middle phalanges to recreate A2 and A4 function, respectively. RESULTS: After complete venting of the A2, A3, and A4 pulleys, proximal interphalangeal joint ROM significantly decreased by 13.4° ± 2.7° and distal interphalangeal joint ROM decreased by 15.8° ± 2.1°. Application of external rings over the proximal and middle phalanx resulted in a residual ROM decrease of 8.3° ± 1.9° at the proximal interphalangeal joint and 7.9° ± 2.1° at the distal interphalangeal joint, nearly restoring ROM. Similarly, complete pulley venting resulted in reduced FDS load by 37% and FDP load by 50% compared with intact pulleys. After application of external rings, loads were restored almost to normal, with a 9% reduction for FDS load and 9% reduction for FDP load compared with intact pulleys. CONCLUSIONS: The application of thermoplastic rings acting as external pulleys is an effective, noninvasive, and reproducible approach to restore flexor tendon biomechanics and digit ROM after pulley venting. CLINICAL RELEVANCE: Thermoplastic rings may be a useful therapeutic adjunct in restoring joint ROM and flexor tendon loads after surgical venting of the pulleys.

Development of an EMG-Based Muscle Health Model for Elbow Trauma Patients.

Wearable robotic braces have the potential to improve rehabilitative therapies for patients suffering from musculoskeletal (MSK) conditions. Ideally, a quantitative assessment of health would be incorporated into rehabilitative devices to monitor patient recovery. The purpose of this work is to develop a model to distinguish between the healthy and injured arms of elbow trauma patients based on electromyography (EMG) data. Surface EMG recordings were collected from the healthy and injured limbs of 30 elbow trauma patients while performing 10 upper-limb motions. Forty-two features and five feature sets were extracted from the data. Feature selection was performed to improve the class separation and to reduce the computational complexity of the feature sets. The following classifiers were tested: linear discriminant analysis (LDA), support vector machine (SVM), and random forest (RF). The classifiers were used to distinguish between two levels of health: healthy and injured (50% baseline accuracy rate). Maximum fractal length (MFL), myopulse percentage rate (MYOP), power spectrum ratio (PSR) and spike shape analysis features were identified as the best features for classifying elbow muscle health. A majority vote of the LDA classification models provided a cross-validation accuracy of 82.1%. The work described in this paper indicates that it is possible to discern between healthy and injured limbs of patients with MSK elbow injuries. Further assessment and optimization could improve the consistency and accuracy of the classification models. This work is the first of its kind to identify EMG metrics for muscle health assessment by wearable rehabilitative devices.

Zone III flexor tendon injuries - A proposed modification to rehabilitation.

In this manuscript, these authors have utilized years of clinical experience to suggest rehabilitation modifications for Zone III flexor tendon injuries. - VictoriaPriganc, PhD, OTR, CHT, CLT, Practice Forum Editor.

Zone-specific pitfalls in flexor tendon rehabilitation: management and prevention.

Despite significant advancements in flexor tendon repair techniques and rehabilitation strategies, achieving complete restoration of digital motion remains a formidable challenge. The most prevalent complications associated with tendon repair are the development of tendon adhesions and joint contractures. Left unaddressed, these complications can further lead to secondary pathomechanical changes, resulting in fixed deformities significantly affecting hand function. This review of zone-specific considerations in flexor tendon rehabilitation provides an in-depth analysis of the dynamics of tendon motion after repair and strategies to minimize common secondary complications.

Static progressive orthosis for patients with limited radial and/or ulnar deviation: an innovative orthotic design.

After injury to the wrist and forearm, therapists and patients frequently work to regain the motions of wrist flexion/extension and forearm pronation/supination. Although these motions play a vital role in everyday functioning, for some, limitations in wrist radial/ulnar deviation can also present functional challenges. These authors describe the creation and utilization of a static progressive orthosis to assist a patient in regaining wrist radioulnar deviation

Alternative Noninvasive Treatment of Unstable Extra-articular Proximal and Middle Phalangeal Fractures: A Static Linear Traction Orthosis Design.

Extra-articular unstable proximal and middle phalanx fractures are typically managed with surgical means with common complications of tendon tethering, stiffness, and secondary hand dysfunction. As a result, alternative conservative measures are being explored. The use of static linear traction through the application of an orthosis allows for fracture reduction and anatomic healing, with successful range of motion outcomes.

Development of an In Vitro Swan Neck Deformity Biomechanical Model.

BACKGROUND: Injury to the finger's extensor mechanism is a common cause of swan neck deformity (SND). Progression of extensor and flexor tendon imbalance negatively affects laxity of the volar plate, resulting in the inhibition of proper finger motion. The complexity of finger anatomy, however, makes understanding the pathomechanics of these deformities challenging. Therefore, development of an SND model is imperative to understand its influence on finger biomechanics and to provide an in vitro model to evaluate the various treatment options. METHODS: The index, middle, and ring fingers from 8 cadaveric specimens were used in an in vitro active motion simulator to replicate finger flexion/extension. An SND model was developed through sectioning of the terminal extensor tendon at the distal insertion (creating a mallet finger) and transverse retinacular ligament (TRL). A strain gauge inserted under the volar plate measured laxity of the plate, and electromagnetic trackers recorded proximal interphalangeal joint (PIPJ) angles. RESULTS: Strain in the volar plate increased progressively with creation of the mallet and SND conditions (P = .015). Although not statistically significant, the mallet finger condition accounted for 26% of the increase, whereas sectioning of the TRL accounted for 74% (P = .031). As predicted, PIPJ hyperextension was not detectable by joint angle measurement; however, the PIPJ angle had a strong positive correlation with volar plate strain (R2 = 1.0, P < .001). CONCLUSION: Volar plate strain measurement, in an in vitro model, can detect an induced SND. Moreover, as a surrogate for PIPJ hyperextension, volar plate strain may be useful to evaluate the time-zero effectiveness of various surgical interventions.

Rehabilitation Following Nerve Transfer Surgery.

Nerve transfer surgery is an important new addition to the treatment paradigm following nerve trauma. The following rehabilitation plan has been developed over the past 15 years, in an interdisciplinary, tertiary peripheral nerve program at the "Roth|McFarlane Hand and Upper Limb Centre." This center evaluates more than 400 patients with complex nerve injuries annually and has been routinely using nerve transfers since 2005. The described rehabilitation program includes input from patients, therapists, physiatrists, and surgeons and has evolved based on experience and updated science. The plan is comprised of phases which are practical, reproducible and will serve as a framework to allow other peripheral nerve programs to adapt and improve the "Roth|McFarlane Hand and Upper Limb Centre" paradigm to enhance patient outcomes.

Identifying Interaction Forces Via EMG Under Changing Motion Dynamics.

Musculoskeletal injuries can severely inhibit performance of activities of daily living. In order to regain function, rehabilitation is often required. Assistive rehabilitation devices can be used to increase arm mobility by guiding therapeutic exercises or assisting with motion. Electromyography (EMG) may be able to provide an intuitive interface between the patient and the device if appropriate classification models allow smart systems to relate these signals to the desired device motion. Unfortunately, the accuracy of pattern recognition models classifying motion in constrained laboratory environments significantly drops when used for detecting dynamic unconstrained movements. The objectives of this study were to quantity how various motion factors affect arm muscle activations during dynamic motion, and to use these motion factors and EMG signals for detecting interaction forces between the person and the environment during motion. The results quantity how EMG features change significantly with variations in arm positions, interaction forces, and motion velocities. The results also show that pattern recognition models were able to detect intended characteristics of motion based solely on EMG signals. Prediction of force was improved from 73.77% correct to 79.17% accuracy during elbow flexion-extension by properly selecting the features, and providing measurable arm position and velocity information as additional inputs to a linear discriminant analysis model.

Enhancing the Therapist-Device Relationship: Software Requirements for Digital Collection and Analysis of Patient Data.

Improving upon the therapist-device relationship is an important aspect that will increase the number of upper-limb robotic rehabilitation devices being used for therapy. One path to strengthen this relationship is for these devices to generate large data sets that rehabilitation therapists can use to enhance their patient assessment procedures. In this article, a national survey of Canadian therapists was conducted in order to learn about their data collection and analysis methods. A total of 33 responses were gathered from an online survey. These results show that there is a demand for the collection and visualization of various patient data, some of which cannot be easily collected with existing methods. It was also seen that there exists a large variation between therapists about which major steps constitute the general rehabilitation process. From these results, a set of fourteen general software requirements has been created. Insights from the survey regarding influences on software designs are briefly discussed. This research helps to enable the development of software systems that increase the interaction potential between therapists and robotic devices.

A Wearable Mechatronic Glove for Resistive Hand Therapy Exercises.

Recent technological improvements are consistently improving the efficacy of wearable mechatronic devices designed to support rehabilitation. However, it has been identified that there is currently a limited number of devices that can perform resistive motion tasks. To address this limitation, a Wearable Mechatronics-Enabled (WearME) Glove has been developed to support rehabilitative motion tasks. Using the WearME Glove, a control system was developed to enable the performance of resistive finger and wrist motion tasks. An initial evaluation of the device applied to rehabilitation tasks shows that average control errors of 2.4% and 1.5% were achieved for a resistive finger task and a resistive wrist flexion-extension task, respectively. In addition, an analysis of each task showed that for the index finger, the thumb and the wrist motion, an average of 69%, 76% and 83% of the duration, respectively, were being resisted by the WearME Glove. The results of this study show that the WearME glove can provide consistent resistance to the finger and wrist for different rehabilitation tasks.

Variation of Grip Strength and Wrist Range of Motion with Forearm Rotation in Healthy Young Volunteers Aged 23 to 30.

Background Grip strength and wrist range of motion (ROM) are important metrics used to evaluate hand rehabilitation and outcomes of wrist interventions. Published normative data on these metrics do not recognize the contribution of forearm rotation. This study aims to identify and quantify variations in grip strength and wrist ROM with forearm rotation in healthy young individuals. Materials and Methods Wrist ROM and grip strength were measured in 30 healthy volunteers aged 23 to 30. Participant demographics, grip strength, and wrist ROM (wrist flexion and extension, ulnar and radial deviation) at three forearm positions (full supination, neutral, and full pronation) were measured using a digital dynamometer and standard goniometers. Data analysis was conducted using a one-way repeated measure ANOVA. Forearm position values were compared using post hoc analysis. Results Grip strength in males was greatest in neutral position (males: nondominant 51.4 kg, dominant 56.1 kg) followed by supination (males: nondominant 46.6 kg, dominant 51.7 kg) and weakest in pronation (males: nondominant 40.1 kg, dominant 42.9 kg). Grip strength in females was similar between supination (nondominant: 26.1 kg, dominant: 28.5 kg) and neutral (nondominant: 27.4 kg, dominant: 29.1 kg) positions, but both were greater than in pronation (nondominant: 22.3 kg, dominant: 24.1 kg). Wrist flexion in males was significantly reduced in supination compared with neutral and pronated positions (nondominant: supination 63.1°, neutral 72.6°, pronation 73.3°; dominant: supination 62.4°, neutral 70.2°, pronation 70.3°), whereas not significant wrist flexion in females was also weaker in supination (supination 74.4°, neutral 79.9°). Wrist extension in males was greater in pronation (supination 64.6°, pronation 69.5°) whereas females showed no significant difference in any of the forearm positions. Ulnar deviation in males did not differ with forearm position, but females demonstrated greater ulnar deviation in supination on the nondominant hand (supination 44.6°, pronation 33.2°). Whereas there was no difference in radial deviation with forearm position in females, it was markedly greater in pronation versus supination on both sides in males (nondominant: supination 16.3°, pronation 24.6°; dominant: supination 15.4°, pronation 23.9°). Conclusion This study characterizes variations in grip strength and wrist ROM in three forearm positions in healthy young individuals. All measurements differed with forearm rotation and were not influenced by hand dominance. These results suggest that wrist ROM and grip strength should be evaluated in different positions of forearm rotation, rather than a fixed position. This has functional implications particularly in patients involved with specialized activities such as sports, instrument-playing, or work-related activities.

Optimizing elbow rehabilitation after instability.

Elbow instability is a common clinical problem that requires careful assessment and treatment to achieve a successful outcome. Rehabilitation is a key element in achieving a stable mobile elbow. Careful communication between the treating therapist and surgeon is essential so that an optimal rehabilitation program can be developed and implemented. By understanding the patterns of injury and the biomechanics of the elbow, a good outcome can be achieved in most patients who have elbow instability.

The Use of Dynamic Assist Orthosis for Muscle Reeducation following Brachial Plexus Injury and Reconstruction.

Therapeutic management of brachial plexus injuries remains complex. The impact of brachial plexus injuries on everyday human functioning should not be underestimated. Early active-assisted range of motion following such injuries may prevent myostatic contractures, minimize muscle atrophy, facilitate muscle fiber recruitment, and enable a faster return to baseline strength levels. The dynamic assist elbow flexion orthosis proposed is designed to provide patients with a graded system for muscle reeducation and function. No clinical data are currently available on the use of this orthosis design; however, this article presents a treatment option based on sound clinical reasoning to facilitate rehabilitation following this devastating injury.

The Effect of Simulated Total Distal Interphalangeal Joint Stiffness on Grip Strength.

PURPOSE: Production of a functional grip pattern requires the concerted action of numerous structures within the hand. This study quantifies the effect of total distal interphalangeal joint (DIPJ) stiffness to grip strength. METHODS: Fifty (25 men, 25 women, 100 hands) individuals with a mean age of 38 years (range: 17-69 years) were recruited. Exclusion criteria included history of previous upper limb injury, neuropathies, or systemic disease. Custom thermoplastic orthoses were used to splint participants' DIPJ in full extension simulating stiffness. Grip strength before and after splinting was measured using a calibrated Jamar dynamometer. Data were analyzed using paired and independent sample t tests and 2 × 2 repeated-measures analysis of variance with hand dominance and configuration (splinted or unsplinted) as within-subject factors. RESULTS: Restriction of DIPJ flexion led to a 20% decrease in grip strength (P < .001). There was no significant difference in this decrease between dominant and non-dominant hands. Univariate analysis did not demonstrate any interaction between hand dominance and testing configuration. Post hoc analysis revealed no statistical difference in baseline grip strength between the dominant and non-dominant hands. Furthermore, men had significantly stronger grip strength than women in all configurations (P < .001). CONCLUSIONS: Flexion at the DIPJ contributes significantly to grip strength, and stiffness at this joint greatly limits functional capabilities of the hand. This necessitates the need for targeted rehabilitation in DIPJ injuries to minimize adverse effects on grip strength.

OBJECTIF: Pour produire un schéma de préhension fonctionnel, il faut l'action concertée de multiples structures de la main. La présente étude quantifie l'effet de la raideur de toute l'articulation interphalangienne distale (AIPD) sur la force de préhension. MÉTHODOLOGIE: Les chercheurs ont recruté 50 personnes (25 hommes, 25 femmes, 100 mains) d'un âge moyen de 38,28 ans (plage de 17 à 69 ans). Les critères d'exclusion incluaient des antécédents de blessure d'un membre supérieur, de neuropathie ou de maladie systémique. Les chercheurs ont utilisé des orthèses thermoplastiques sur mesure pour mettre une attelle sur l'AIPD en pleine extension des participants, afin de simuler la raideur. Ils ont mesuré la force de préhension avant et après la pose de l'attelle à l'aide d'un dynanomètre Jamar calibré. Ils ont évalué les données à l'aide de tests de Student appariés et indépendants et de l'analyse de variance à mesures répétées 2×2 et se sont servis de la dominance de la main et de la configuration (avec ou sans attelle) comme facteurs individuels. RÉSULTATS: La restriction de la flexion de l'AIPD suscitait une diminution de la force de préhension de 20 % (P < 0,001). Il n'y avait pas de différence significative entre les mains dominantes et non dominantes. L'analyse univariée n'a pas démontré d'interaction entre la dominance de la main et la configuration des tests. L'analyse a posteriori n'a révélé aucune différence statistique de la force de préhension entre les mains dominantes et non dominantes en début d'étude. De plus, les hommes avaient une beaucoup plus grande force de préhension que les femmes dans toutes les configurations (P < 0,001). CONCLUSIONS: La flexion de l'AIPD contribue de manière significative à la force de préhension, et la raideur de l'articulation limite considérablement la capacité fonctionnelle de la main. Ainsi, il faut prévoir une réadaptation ciblée des lésions de l'AIPD pour en réduire le plus possible les effets indésirables sur la force de préhension.

Postoperative healing patterns in elbow using electromyography: Towards the development of a wearable mechatronic elbow brace.

Musculoskeletal (MSK) conditions are the most common cause of severe long-term pain and physical disability. Current postoperative treatment for patients requires them to follow a long-term physiotherapy program customized for each specific case; however, this process can be complex, time-consuming and without the right therapy it may end up being ineffective. A possible solution involves the development of wearable mechatronic elbow braces that use electromyography (EMG) to identify patient intent. However, EMG characteristics change based on the health of the individual and therefore require further investigation. In order to quantify the progress of MSK injury patients and assess their neuromuscular health, EMG signals from 16 healthy individuals and 15 postoperative patients were collected and analyzed. The experiments conducted show that EMG can be used as a method for assessing MSK health. A normal range across the muscle groups has been identified to which the patient population was compared. This showed statistically significant differences in the magnitudes of muscle recruitment and activation between the two groups. Furthermore, a comparison within the patient population at the beginning of their therapy versus at the end of their therapy was conducted. Statistical differences arose in this second analysis further proving that patients' signals tend to change and show trends closer to those of the healthy population.

The Effect of Isolated Finger Stiffness on Adjacent Digit Function.

BACKGROUND: Isolated stiffness in a single finger can affect the function of adjacent digits and decrease overall hand function due to the quadriga phenomenon. This study objectively quantifies the dysfunctional impact of each individual stiff finger upon the remaining digits. METHODS: Twenty-five individuals (10 men and 15 women) with a mean age of 31 years (range, 18-58 years) without any upper limb pathology, neuropathy, or systemic illness were recruited. Volar-based finger splints were used to hold individual digits of the dominant hand (24 right and 1 left) sequentially in full extension at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints. Motion of the remaining 3 nonsplinted digits was assessed using a finger goniometer and linear scale to measure the total active range of motion (TAM) and fingertip-to-distal palmar crease (DPC) distance. TAM before and after splinting for each digit was compared using 1-way analysis of variance (ANOVA). RESULTS: Splinting of any individual finger resulted in a significant reduction in the TAM of all adjacent fingers, regardless of which finger was splinted ( P < .001). Digits immediately adjacent to the splinted finger were more heavily impacted compared with nonadjacent digits. Splinting of the ring finger produced the greatest detriment, with a 26% to 47% reduction in the TAM and a DPC distance greater than 40 mm in a third of participants. The index finger caused the least disturbance to remaining digital motion. CONCLUSIONS: Isolated finger stiffness causes a variable degree of dysfunction on adjacent normal digits. This emphasizes the need for a focused and proactive approach to restore full active motion following isolated finger injuries to prevent persistent functional sequelae of the hand.

Dynamic assist splinting for attenuated sagittal bands in the rheumatoid hand.

The extensor mechanism of the hand is complex, requiring effective functioning of all involved structures, including the sagittal bands. The sagittal bands function to maintain the extensor tendons in midline and to limit their distal excursion. Injury to the sagittal bands or sagittal band attenuation can cause instability and ulnar displacement/subluxation of the extensor tendons into the valleys between the digits and lead to a subsequent loss of active finger extension at the metacarpophalangeal joints. Secondary conditions may also develop, such as swan-neck deformity, as is frequently observed in the rheumatoid arthritis population. To prevent or reduce an extension lag and secondary changes and to maintain the functional use of the hand, a dynamic metacarpophalangeal extension assist splint is necessary. This splint enables extension at the metacarpophalangeal joints, thus enabling the functional use of the hand. This article reviews the biomechanics of the sagittal bands and the corrections that enable finger extension at the metacarpophalangeal joints, thus preventing secondary conditions.