Finite element analysis of the performance of additively manufactured scaffolds for scapholunate ligament reconstruction

Rupture of the scapholunate interosseous ligament can cause the dissociation of scaphoid and lunate bones, resulting in impaired wrist function. Current treatments (e.g., tendon-based surgical reconstruction, screw-based fixation, fusion, or carpectomy) may restore wrist stability, but do not address regeneration of the ruptured ligament, and may result in wrist functional limitations and osteoarthritis. Recently a novel multiphasic bone-ligament-bone scaffold was proposed, which aims to reconstruct the ruptured ligament, and which can be 3D-printed using medical-grade polycaprolactone. This scaffold is composed of a central ligament-scaffold section and features a bone attachment terminal at either end. Since the ligament-scaffold is the primary load bearing structure during physiological wrist motion, its geometry, mechanical properties, and the surgical placement of the scaffold are critical for performance optimisation. This study presents a patient-specific computational biomechanical evaluation of the effect of scaffold length, and positioning of the bone attachment sites. Through segmentation and image processing of medical image data for natural wrist motion, detailed 3D geometries as well as patient-specific physiological wrist motion could be derived. This data formed the input for detailed finite element analysis, enabling computational of scaffold stress and strain distributions, which are key predictors of scaffold structural integrity. The computational analysis demonstrated that longer scaffolds present reduced peak scaffold stresses and a more homogeneous stress state compared to shorter scaffolds. Furthermore, it was found that scaffolds attached at proximal sites experience lower stresses than those attached at distal sites. However, scaffold length, rather than bone terminal location, most strongly influences peak stress. For each scaffold terminal placement configuration, a basic metric was computed indicative of bone fracture risk. This metric was the minimum distance from the bone surface to the internal scaffold bone terminal. Analysis of this minimum bone thickness data confirmed further optimisation of terminal locations is warranted.

Evaluation of the Efficiency of Supinator Tendon Transfer to Wrist Extensor in Brachial Plexus Injuries at C7-T1, A Case Study Based on OpenSIM Modelling Approach

BackgroundThe incidence of brachial plexus injuries (BPI) is increasing due to improvement in transportation technology. Those with BPI have upper limb performance limitation depends on the type of injury. Various surgical treatments have been used in this group of the subjects to restore their performance. The aim of this study was to evaluate the efficiency of supinator transferred to wrist extensors in those with lesion level at C7-T1 based on OpenSim modelling approach.MethodThe motions of the upper limb during vertical reaching, transverse reaching and wrist motion of a normal subject were achieved by use of motion analysis system. The ranges of motion of the upper limb joints were evaluated by inverse kinematic. OpenSim software was used to determine the muscles forces during aforementioned tasks. Tendon of supinator was transferred to extensors in modified models of OpenSim. Forward dynamic approach was used to determine the range of motion in tendon transferred condition. ResultsThe range of wrist motion in normal condition (extensors intake) were 85, 103 and 140 degrees for the first task (transverse reaching), the second task (vertical reaching) and the third task (only flexion/extension of wrist), respectively. Although the force of supinator was significantly less than that of wrist extensors, the pattern of its force is the same as wrist extensors.

SLAC and SNAC Wrist: The Top Five Things That General Radiologists Need to Know

Wrist osteoarthritis (OA) is a common painful condition that affects the patient’s quality of life by limiting the range of wrist motion and grip strength. Wrist OA often results from scapholunate advanced collapse (SLAC) or scaphoid nonunion advanced collapse (SNAC). Early diagnosis of SLAC and SNAC is crucial because it affects treatment planning. Thus, radiologists should be able to interpret the early imaging findings. This pictorial review discusses the pathophysiology and the clinical symptoms of SLAC and SNAC and presents the imaging findings with emphasis on the proper imaging algorithm. Finally, it focuses on the treatment according to the degenerative status of each of these patterns.

Facilitative Exercise for Surface Myoelectric Activity Using Robot Arm Control System – Training Scheme with Gradually Increasing Difficulty Level –

Various control systems for robot arms using surface myoelectric signals have been developed. Abundant pattern-recognition techniques have been proposed to predict human motion intent based on these signals. However, it is laborious for users to train the voluntary control of myoelectric signals using those systems. In this research, we aim to develop a rehabilitation support system for hemiplegic upper limbs with a robot arm controlled by surface myoelectric signals. In this study, we construct a simple one-link robot arm that is controlled by estimating the wrist motion from the surface myoelectric signals on the forearm. We propose a training scheme with gradually increasing difficulty level for robot arm manipulation to evoke surface myoelectric signals. Subsequently, we investigate the possibility of facilitative exercise for the voluntary surface myoelectric activity of the desired muscles through trial experiments.

Biomechanical Comparison of Dart-Throw Motions after Partial Wrist Fusions

Background Multiple partial wrist fusions exist for the management of arthritic disease. Limited information is available on their effect on wrist range of motion in the dart-throwing direction of wrist motion, even though it is used in most activities of daily living. Purpose The purpose of this study was to measure the retained motion for different orientations of dart-throwing motion for seven different partial wrist fusions and proximal row carpectomy (PRC). Methods Eight fresh frozen right cadavers were tested with the wrist intact and followed simulated fusions. Fusions were performed using an external fixation technique and included scaphocapitate, scapholunate (SL), capitolunate, radiolunate, radioscapholunate, scaphotrapeziotrapezoid, 4 corner fusion, and PRC. Results In the intact wrist, the average arc of wrist motion with the wrist oriented at 20 degrees away from the flexion-extension axis was significantly larger than at any other orientation of motion. All partial wrist fusions and the PRC had significantly smaller average dart-throw arc of motion compared with intact at an orientation 20 and 25 degrees away from flexion-extension. The SL fusion provided a significantly larger arc of motion than most of the other fusions at most orientations. Conclusion/Clinical Relevance This study provides a comprehensive compilation of the range of motion in a functional plane, “the dart-throw motion,” for limited wrist fusions and PRC. These data provide the clinician with important information that can be used to educate patients regarding expectations after surgery.

Accuracy of a Low-Cost 3D-Printed Wearable Goniometer for Measuring Wrist Motion

Wrist motion provides an important metric for disease monitoring and occupational risk assessment. The collection of wrist kinematics in occupational or other real-world environments could augment traditional observational or video-analysis based assessment. We have developed a low-cost 3D printed wearable device, capable of being produced on consumer grade desktop 3D printers. Here we present a preliminary validation of the device against a gold standard optical motion capture system. Data were collected from 10 participants performing a static angle matching task while seated at a desk. The wearable device output was significantly correlated with the optical motion capture system yielding a coefficient of determination (R2) of 0.991 and 0.972 for flexion/extension (FE) and radial/ulnar deviation (RUD) respectively (p < 0.0001). Error was similarly low with a root mean squared error of 4.9° (FE) and 3.9° (RUD). Agreement between the two systems was quantified using Bland–Altman analysis, with bias and 95% limits of agreement of 3.1° ± 7.4° and −0.16° ± 7.7° for FE and RUD, respectively. These results compare favourably with current methods for occupational assessment, suggesting strong potential for field implementation.

Immobilization of the Wrist After Dorsal Wrist Ganglion Excision: A Systematic Review and Survey of Current Practice

Background Postoperative care after dorsal wrist ganglion (DWG) excision is highly varied. The effect of immobilization of the wrist on patient outcomes has not yet been examined. Methods A systematic review of the literature was performed to determine whether wrist immobilization after DWG surgical excision is beneficial. A survey of hand surgeons in Canada was performed to sample existing practice variations in current immobilization protocols after DWG excision. Results A systematic review yielded 11 studies that rigidly immobilized the wrist (n = 5 open excision, n = 5 arthroscopic excision, n = 1 open or arthroscopic excision), 10 studies that used dressings to partially limit wrist motion (n = 5 open, n = 5 arthroscopic), 1 study (open) that did either of the above, and 2 studies (arthroscopic) that did not restrict wrist motion postoperatively. This ranged from 48 hours to 2 weeks in open DWG excision and 5 days to 3 weeks in arthroscopic DWG excision. The survey of Canadian hand surgeons had a similarly divided result of those who chose to immobilize the wrist fully (41%), partially (14%), or not at all (55%). Most surgeons surveyed who immobilized the wrist postoperatively did so for 1 to 2 weeks. Conclusion The systematic review and survey of Canadian hand surgeons reveal that hand surgeons are divided regarding the need to immobilize the wrist after DWG excision. In terms of functional outcome, there is no compelling data to suggest 1 strategy is superior. The time frame for immobilization when undertaken was short at 2 weeks or less. The systematic review is registered in the PROSPERO database (PROSPERO 2016:CRD42016050877).

Finite element analysis of the performance of additively manufactured scaffolds for scapholunate ligament reconstruction

Rupture of the scapholunate interosseous ligament can cause the dissociation of scaphoid and lunate bones, resulting in impaired wrist function. Current treatments (e.g., tendon-based surgical reconstruction, screw-based fixation, fusion, or carpectomy) may restore wrist stability, but do not address regeneration of the ruptured ligament, and may result in wrist functional limitations and osteoarthritis. Recently a novel multiphasic bone-ligament-bone scaffold was proposed, which aims to reconstruct the ruptured ligament, and which can be 3D-printed using medical-grade polycaprolactone. This scaffold is composed of a central ligament-scaffold section and features a bone attachment terminal at either end. Since the ligament-scaffold is the primary load bearing structure during physiological wrist motion, its geometry, mechanical properties, and the surgical placement of the scaffold are critical for performance optimisation. This study presents a patient-specific computational biomechanical evaluation of the effect of scaffold length, and positioning of the bone attachment sites. Through segmentation and image processing of medical image data for natural wrist motion, detailed 3D geometries as well as patient-specific physiological wrist motion could be derived. This data formed the input for detailed finite element analysis, enabling computational of scaffold stress and strain distributions, which are key predictors of scaffold structural integrity. The computational analysis demonstrated that longer scaffolds present reduced peak scaffold stresses and a more homogeneous stress state compared to shorter scaffolds. Furthermore, it was found that scaffolds attached at proximal sites experience lower stresses than those attached at distal sites. However, scaffold length, rather than bone terminal location, most strongly influences peak stress. For each scaffold terminal placement configuration, a basic metric was computed indicative of bone fracture risk. This metric was the minimum distance from the bone surface to the internal scaffold bone terminal. Analysis of this minimum bone thickness data confirmed further optimisation of terminal locations is warranted.

True Symphalangism of All Bilateral Proximal Interphalangeal Joints with Multi-carpal Coalition and Hypoplasia of the Ulnar Styloid Process

Symphalangism is a rare genetic condition characterized by ankylosis of the proximal interphalangeal (PIP) or/and distal interphalangeal (DIP) joints. The patient presented with fused bilateral PIP joints and poor flexion, and an unsatisfactory range of motion (ROM) in the metacarpophalangeal (MP) and DIP joints. Concomitantly, multi-carpal coalition, proximal carpal malalignment, and ulnar styloid process abnormality were also observed in radiographs obtained at diagnosis. Rehabilitation training of the MP and DIP joints and a wrist supporter were recommended to achieve MP and DIP functional motion and restrict dramatic wrist motion. This is the first case report of symphalangism with multi-carpal coalition and abnormality of the ulnar styloid process to the best of our knowledge.

RADIOSCAPHOLUNATE (RSL) FUSION ON SECONDARY OA WRIST WITH NEGLECTED DISLOCATION RADIOCARPAL JOINT AND CONTRACTURE DUE TO ENTRAPMENT OF SUPERFICIAL FLEXOR TENDON INDEX FINGER OF LEFT HAND

ABSTRACT Background: When pain, deformity and instability compromise wrist function, wrist stabilization by means of fusion is a procedure of recognized validity. The goal of wrist arthrodesis is to provide the patient with a stable wrist for power grip and the predictable relief of pain while sacrificing wrist motion. The radioscapholunate (RSL) fusion is one of salvage procedure indicated in the case of traumatic or degenerative osteoarthritis of the radiocarpal joint, involving the lunate facet of the radius. RSL-fusion reduced total wrist motion (3 MC/Rad) in the F/E axis to an average of 49% of F/E in the unfused wrist but preserves midcarpal joint motion while alleviating pain. Case Report: We report a 43-year-old male patient with pain on his left wrist. 10 months before admission, he felt down from stairs with his left hand bear his body weight. He broke his wrist and got surgery at that time. Because still feel pain and his index finger can’t fully extensed, he brought to Soeharso orthopaedic hospital. Here, we have done RSL-fusion using cross pinning K-Wire to reduce pain, distal scapoid excision to optimizing radial angulation and release superficial flexor tendon index finger of left hand. Discussion: With Secondary OA of left wrist post traumatic with neglected radiocarpal dislocation and superficial flexor tendon contracture due to entrapment index finger of left hand post RSL-fusion, distal scapoid excision and release contracture can reduce pain at radiocarpal joint and improve range of movement. Conclusion: The goal of Radioscapholunate (RSL) fusion is to optimizing wrist motion and strength while minimizing or eliminating pain Keywords: Radioscapholunate fusion, partial wrist arthrodesis, limited wrist fusion, reduce pain