Porous Frameworks Based on Supramolecular Ball Joints: Bringing Flexibility to Ordered 3D Lattices.

XOFs-type materials (X=M, C, S, that is, metal-organic frameworks, covalent organic frameworks and supramolecular organic frameworks, respectively) share a common unifying feature: mutual spatial orientation of constituting components is strictly directional and unchanging by design. Herein, we illustrate an alternate design for porous architectures, as rigid joints constituted by coordinative (MOFs), covalent (COFs), or hydrogen-donor/acceptor (SOFs) bonds, are replaced by supramolecular ball joints, which confer unprecedented flexibility, especially angular, to porous networks. The obtained frameworks remain highly organized but are also permutable: lacking a forced convergence towards an immutable minimum energy structure, these systems remain able to adjust depending on external conditions. Results of POF (permutable organized framework) synthesis is a family of structures rather than a single pre-determined three-dimensional arrangement, as we demonstrate with an illustrative set of 5 XRD structures.

Partial Ossicular Reconstruction With a Novel Ball Joint Prosthesis: The mCLIP ARC Partial Prosthesis.

OBJECTIVE: Middle ear surgery involves reconstruction of the ossicular chain, predominately using rigid implants. New middle ear prostheses strive to mimic the physiologic micromovements of the ossicular chain and prevent dislocation, protrusion, and preloading of the annular ligament due to pressure fluctuations. METHODS: Thirty-five patients were included in a monocentric, prospective observational study. Patients received tympanoplasty with ossicular reconstruction using the mCLIP ARC partial prosthesis. This titanium prosthesis is equipped with a clip mechanism for coupling at the stapes and a ball joint connecting headplate and shaft. At short-term (ST) and mid-term (MT) follow-up, pure-tone audiometry was performed and the pure tone average of 0.5, 1, 2, and 3 kHz (PTA4) was calculated. The audiological outcome was compared with retrospective data of the Dresden titanium clip prosthesis. RESULTS: The new prosthesis shows favorable clinical results. Pure-tone audiometry showed satisfactory results in ST and MT follow-up, with the PTA4 air-bone gap (ABG) decreasing from 24.5 (±11) dB to 17.4 (±7.9) dB at the ST follow-up at 27 days to 15.6 (±10.3) dB at MT follow-up at 196 days (n = 32). A PTA4-ABG value of less than 20 dB was achieved by 63% of patients at ST follow-up and by 77% at MT follow-up. There was no significant difference in PTA4 ABG compared to the Dresden titanium clip prosthesis during ST follow-up (p = 0.18). CONCLUSION: The mCLIP ARC partial prosthesis, a new middle ear prosthesis with a balanced ball joint, shows promising audiological results and is a safe and effective choice for patients with chronic ear disease. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:3323-3328, 2024.

A Partial Ossicular Replacement Prosthesis With a Concentric Ball Joint in the Headplate.

OBJECTIVE: In passive middle ear prosthetics, rigid implants have proven successful in reconstructing the ossicular chain. However, these cannot fully replicate the physiology of the ossicular chain. Pressure fluctuations cause high stresses in rigid passive prostheses, which can result in dislocation, protrusion, and pre-tension in the annular ligament resulting in unsatisfactory hearing results. METHODS: In collaboration with MED-EL, we developed a new passive middle ear prosthesis that features a balanced, centered ball joint between the headplate and shaft of the prosthesis. We compared the sound transmission properties of this new prosthesis with those of a standard rigid prosthesis. Using Laser-Doppler-Vibrometry, we measured the sound-induced velocity of the stapes footplate relative to a given acoustic stimulus. RESULTS: The new prosthesis showed equivalent sound transmission characteristics compared to the rigid prosthesis, whereas retaining the ability to compensate for pressure fluctuations due to its ball joint. This ensures good transmission properties even during displacements of the tympanic membrane. CONCLUSION: This development is a further step toward a physiological reconstruction of the ossicular chain. LEVEL OF EVIDENCE: NA Laryngoscope, 133:1717-1721, 2023.

Design and Development of a Continuum Robot with Switching-Stiffness.

Continuum robots have the advantages of agility and adaptability. However, existing continuum robots have limitations of low stiffness and complex motion modes, and the existing variable stiffness methods cannot achieve a wide range of stiffness changes and fast switching stiffness simultaneously. A continuum robot structure, switching stiffness method, and motion principle are proposed in this article. The continuum robot is made up of three segments connected in series. Each segment comprises multiple spherical joints connected in series, and the joints can be locked by their respective airbag. A valve controls each airbag, quickly switching the segment between rigidity and flexibility. The motion of the segments is driven by three cables that run through the robot. The segment steers only when it is unlocked. When a segment becomes locked, it acts as a rigid body. As a result, by locking and unlocking each segment in sequence, the cables can alternately drive all the segments. The stiffness variation and movement of the continuum robot were tested. The segment's stiffness varies from 36.89 to 1300.95 N/m and the stiffness switching time is 0.25-0.48 s. The time-sharing control mode of segment stiffness and motion is validated by establishing a specific test platform and a mathematical model. The continuum robot's flexibility is demonstrated by controlling the fast bending of different segments sequentially.

Correction Method for the Bending Characteristics of Aero Ball Joints under High Temperature and High Pressure.

The aero ball joint is pivotal in aircraft duct systems due to its favorable properties, including displacement compensation and flexibility. In the stress assessment of air ducts, ball joints are usually simplified by using "Joints" connections to reduce the convergence problems caused by non-linearity, which requires a high degree of accuracy in the characteristic parameters of the ball joint. Accordingly, this paper builds a high temperature and pressure fatigue test platform to investigate the bending characteristics of the ball joint at different temperatures and pressures and points out the limitations of the current method. Then, a method combining finite element analysis (FEA) and the BP neural network is proposed to obtain the characteristic parameters of the ball joint. The results showed that the bending process of the ball joint tended to have two typically different stiffness properties, which were high rigidity and low rigidity. The bending characteristics were strongly influenced by pressure, but less influenced by temperature. The existing test platform increased the force reaction at the contact areas of the ball joint, resulting in errors in the measurement of characteristic parameters. The BP neural network prediction method could effectively alter the ball joint properties and reduce errors.

Comparison of total and partial ossicular replacement prostheses in patients with an intact stapes suprastructure.

OBJECTIVES: To compare the results of ossiculoplasty with two different partial ossicular replacement prostheses (PORP) to ossiculoplasty with a total ossicular replacement prosthesis (TORP) in patients with an intact stapes suprastructure. METHODS: All patients required primary or revision surgery for chronic middle ear disease and ossicular reconstruction with either a PORP or a TORP, as well as a with an intact stapes suprastructure. In total, 141 patients receiving classic tympanoplasty with PORP (N = 92), ossiculoplasty with PORP with ball joint (N = 22), or TORP (N = 27) between January 2011 and March 2017 were included in this study. The inclusion criterion was an intact stapes suprastructure. The underlying indication for surgery was either middle ear disease, such as cholesteatoma, or revision surgery for audiological improvement. The main outcome measures were four-frequency pure tone average (0.5, 1, 2, 3 kHz) at early and late follow-up after ossiculoplasty, the effects of clinical factors including the underlying middle ear disease, and primary or revision surgery. RESULTS: All patients showed a significantly reduced air-bone gap (ABG 0.5, 1, 2, 3 kHz) at late follow-up (mean: 18 dB) compared to preoperative measurements (mean: 25.5 dB). A significantly better outcome in ABG closure was shown among patients with a preoperatively intact tympanic membrane, with an intact stapes suprastructure or without preexisting cholesteatoma. Outcome was not significantly influenced by the prosthesis-type, the creation of an open mastoid cavity, the status of the mucosa, or the indication for surgery. CONCLUSION: TORP with an intact stapes suprastructure is a safe procedure and provides audiological outcomes similar to PORP. LEVEL OF EVIDENCE: 2C Laryngoscope, 130:768-775, 2020.

Use of a novel ball-joint guide array for magnetic resonance imaging-guided cannula placement and convective delivery: technical note.

OBJECTIVE: The objective of this study was to assess the feasibility, accuracy, effectiveness, and safety of an MRI-compatible frameless stereotactic ball-joint guide array (BJGA) as a platform for cannula placement and convection-enhanced delivery (CED). METHODS: The authors analyzed the clinical and imaging data from consecutive patients with aromatic l-amino acid decarboxylase (AADC) deficiency who underwent infusion of adeno-associated virus (AAV) containing the AADC gene (AAV2-AADC). RESULTS: Eleven patients (7 females, 4 males) underwent bilateral MRI-guided BJGA cannula placement and CED of AAV2-AADC (22 brainstem infusions). The mean age at infusion was 10.5 ± 5.2 years (range 4-19 years). MRI allowed for accurate real-time planning, confirmed precise cannula placement after single-pass placement, and permitted on-the-fly adjustment. Overall, the mean bilateral depth to the target was 137.0 ± 5.2 mm (range 124.0-145.5 mm). The mean bilateral depth error was 0.9 ± 0.7 mm (range 0-2.2 mm), and the bilateral radial error was 0.9 ± 0.6 mm (range 0.1-2.3 mm). The bilateral absolute tip error was 1.4 ± 0.8 mm (range 0.4-3.0 mm). Target depth and absolute tip error were not correlated (Pearson product-moment correlation coefficient, r = 0.01). CONCLUSIONS: Use of the BJGA is feasible, accurate, effective, and safe for cannula placement, infusion MRI monitoring, and cannula adjustment during CED. The low-profile universal applicability of the BJGA streamlines and facilitates MRI-guided CED.

Development of a novel frameless skull-mounted ball-joint guide array for use in image-guided neurosurgery.

OBJECTIVE: Successful convection-enhanced delivery of therapeutic agents to subcortical brain structures requires accurate cannula placement. Stereotactic guiding devices have been developed to accurately target brain nuclei. However, technologies remain limited by a lack of MRI compatibility, or by devices' size, making them suboptimal for direct gene delivery to brain parenchyma. The goal of this study was to validate the accuracy of a novel frameless skull-mounted ball-joint guide array (BJGA) in targeting the nonhuman primate (NHP) brain. METHODS: Fifteen MRI-guided cannula insertions were performed on 9 NHPs, each targeting the putamen. Optimal trajectories were planned on a standard MRI console using 3D multiplanar baseline images. After cannula insertion, the intended trajectory was compared to the final trajectory to assess deviation (euclidean error) of the cannula tip. RESULTS: The average cannula tip deviation was 1.18 ± 0.60 mm (mean ± SD) as measured by 2 independent reviewers. Topological analysis showed a superior, posterior, and rightward directional bias, and the intra- and interclass correlation coefficients were > 0.85, indicating valid and reliable intra- and interobserver evaluation. CONCLUSIONS: The data demonstrate that the BJGA can be used to reliably target subcortical brain structures by using MRI guidance, with accuracy comparable to current frameless stereotactic systems. The size and versatility of the BJGA, combined with a streamlined workflow, allows for its potential applicability to a variety of intracranial neurosurgical procedures, and for greater flexibility in executing MRI-guided experiments within the NHP brain.

Effect of Ball Joint Location in External Fixator on Wrist Motion in Distal Radius Fractures / 대한정형외과연구학회지

PURPOSE: The effects of ball joint location from axis of rotation on postoperative wrist motion in dynamic external fixator for displaced intra-articular fractures in distal radius were evaluated. MATERIALS AND METHODS: 33 patients who had dynamic external fixative surgery after closed reduction within acceptable range and could be followed at least 1 year were reviewed. They were divided into two groups according to distance (5 mm, 10 mm) of ball joint center from axis of wrist rotation which located in proximal cortex of capitate. These groups were compared by clinical results which were evaluated by range of motion of wrist (flexion, extension, radial deviation, ulnar deviation, pronation, supination) and pain evaluation system. They were also divided into two groups according to direction of ball joint migration (proximal, distal) and evaluated by the same methods. RESULTS: No difference in range of motion and pain was observed between distance 0 mm-5 mm group and >5 mm group (p>0.05). Distance 0 mm-10 mm group showed statistically significant more range of motion in extension, supination and pronation than >10mm group (P0.05). Also no difference in range of motion and pain was observed between proximal migration group and distal group (p>0.05). DISCUSSION AND CONCLUSION: In retrospective analysis of dynamic external fixator, range of wrist motion should be preserved by decrease of changes of ball joint location within 10mm from center of rotation.