Dimensional analysis of the distal phalanx with consideration of distal interphalangeal joint arthrodesis using a headless compression screw

Comparative Finite Element (FE) Analysis of the Mechanical Behavior in an Innovative Nitinol Staple for Arthrodesis in Distal Interphalangeal Joint

Objective

Osteoarthritis (OA) is a source of significant limitations for individuals, health systems, and economies. The most common complications of OA are often associated with risk factors related to chronic diseases, cardiovascular disease, and depression. In this article, a new kind of staple is proposed, designed to provide better strength when subjected to bending and torque loads.

Methods

This innovative staple has been numerically tested and compared to a MEMOFIX staple by Smith + Nephew, in order to evaluate its mechanical behavior. The radius and ulna were fixed at the lower extremity, while the distal interphalangeal of the little finger was loaded with a bending load of 50 N and a torque moment of 500 N/mm2.

Results

For the bending load, a maximum value of stress of 120 MPa in the traditional staple, while 90 MPa are registered in the innovative one. The torsional load produces a value of 107 MPa in the traditional staple and 85 MPa in the innovative one.

Conclusion

Computational simulations showed the biomechanical performance of a new type of nitinol staple compared with a traditional one. This staple is designed with an elliptical shape in order to support different kinds of loads. Our results confirm an optimal mechanical behavior, compared to the traditional staple, in terms of the evaluated Equivalent Von Mises stress; also the contact force exerted by the innovative staple was increased.

Risk factors in distal interphalangeal joint arthrodesis in the hand: a retrospective study of 173 cases

In this retrospective study we aimed to analyse the risk factors for complications after different methods of distal interphalangeal arthrodesis in the hand. Forty-four per cent were treated with K-wire/cerclage fixation, 46% with X-fuse® implants (Stryker GmbH, Selzach, Switzerland) and 10% with headless compression screws (HBS®-screw, KLS Martin Group, Tuttlingen, Germany). The median follow-up was 16 weeks (range 6-224). The overall complication incidence was 44% (minor complications 29% and major 15%). The logistic regression showed that osteoarthritis, revisional arthrodesis and smoking had a negative impact on the total complication incidence. A Cox-regression analysis showed that HBS®-screw arthrodesis was associated with a significantly lower incidence of major complications compared with K-wire/cerclage and X-Fuse®-arthrodesis. Revisional arthrodesis was five times more frequently connected with major complications than primary surgery. Smokers were three times more likely to experience major complications than non-smokers. We conclude that arthrodesis of the distal interphalangeal joint often leads to complications. Risk factors must be kept in mind.Level of evidence: III.

Implementing Monocular Visual-Tactile Sensors for Robust Manipulation

Tactile sensing is an essential capability for robots performing manipulation tasks. In this paper, we introduce a framework to build a monocular visual-tactile sensor for robotic manipulation tasks. Such a sensor is easy to manufacture with affordable ingredients and materials. Based on a marker-based detection method, the sensor can detect the contact positions on a flat or curved surface. In the case study, we have implemented a visual-tactile sensor design specifically through the framework proposed in this paper. The design is low cost and can be processed in a very short time, making it suitable for use as an exploratory study in the laboratory.

Morphological Analysis of Metacarpal Shafts With Respect to Retrograde Intramedullary Headless Screw Fixation

Background: The use of retrograde intramedullary headless compression screw fixation for metacarpal neck and shaft fractures has been described in the literature. The purpose of this study was to perform a computed tomography (CT)-based morphological analysis of metacarpal size to help surgeons anticipate expected hardware needs. Methods: In all, 108 consecutive hand CT scans were evaluated for the medullary diameter in the volar-dorsal and radial-ulnar planes at the narrowest point of the canal, as well as for the distance from the articular surface to this point. Results were then analyzed by finger and by sex. Results: The ring finger had the smallest average medullary canal diameter for both men and women (2.7 and 2.6 mm, respectively); the small finger had the largest average diameter (3.9 mm) for men and the middle finger (3.6 mm) for women. Radial-ulnar was the rate-limiting dimension in the index, middle, and ring fingers, whereas volar-dorsal was the smallest dimension in the small finger, regardless of sex. Medullary diameter tended to be larger in patients aged more than 50 years. More than 50% of fingers have diameters >3.0 mm, and at least 40% of index, middle, and small fingers have diameters >3.5 mm, which are common diameters of commercially available headless compression screws. Conclusions: When preparing to perform open reduction internal fixation of a metacarpal using retrograde intramedullary headless compression screws, the surgeon needs to be prepared with screws of larger diameters to optimize fixation. Screws of larger diameters are needed to achieve endosteal purchase, regardless of sex.

Distal interphalangeal joint arthrodesis with nonaxial multiple small screws: a biomechanical analysis with axial headless compression screw and clinical result of 15 consecutive cases

Background

The axial headless compression screw (AHCS) technique is a widely used method for distal interphalangeal joint (DIPJ) and thumb IPJ arthrodesis. However, it might not be suitable for cases over 10° flexion of fusion angle and extremely small-sized phalanx. Here, the authors describe the nonaxial multiple small screws (NMSS) technique, compare the mechanical strength of the NMSS technique with the AHCS technique, and suggest clinical outcomes of the NMSS technique.

Methods

DIPJ and thumb IPJ arthrodesis models were simulated in the 4th generation composite bone hand. Fixation with three 1.5 mm cortical screws (NMSS) or one HCS (AHCS) was performed in each pair of the phalanx. The bending stiffness and load to failure were tested in 10 pairs of each specimen, and the torsional stiffness and torque to failure were tested in seven pairs of each specimen. Moreover, 15 consecutive clinical DIPJ and thumb IPJ arthrodesis cases were reviewed retrospectively.

Results

The NMSS specimens showed significantly higher bending load to failure, torsional stiffness, and torque to failure than the AHCS specimens. All 15 arthrodesis cases were united without severe complications. The mean fusion angle was 16.3° for the nine cases of the flexed target position.

Conclusions

The NMSS technique showed biomechanical stability comparable to that of the AHCS technique in DIPJ and thumb IPJ arthrodesis. Thus, the NMSS technique could be used as a feasible option in DIPJ and thumb IPJ arthrodesis, especially when a small finger is indicated and a significant flexion angle is required.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05473-9.

Distal interphalangeal Joint Arthrodesis using only Kirschner Wires in small distal Phalanges

PURPOSE

To report the clinical and radiographic results of arthrodesis of relatively small-sized distal interphalangeal joints (DIPJs) using only K-wire fixation.

PATIENTS AND METHODS

Between January 2000 and December 2018 28 arthrodesis in 21 patients (9 males and 12 females with an average age of 52.1 years) with relatively small-sized DIPJs were performed using only K-wires. Data on patient's characteristics, such as age, sex, affected finger, and the number and size of the used k-wires were collected from the medical database. The narrowest diameter of the cortex and medulla of the distal phalanx was measured on preoperative plain radiographs. The time to union and the arthrodesis angle was determined using serial X-ray radiography follow-up. Preoperatively and at the latest follow-up examination, pain using the visual analogue scale (VAS) and the quick DASH score was registered. In addition, complications were investigated.

RESULTS

Average follow-up period was 11.4 months. The small finger was mostly affected (n = 12; 42.9 %). The narrowest diameters of the distal phalanx cortex and the medulla measured on preoperative X-ray images were 2.8 mm (SD 0.5) and 1.2 mm (SD 0.4), respectively. Seven fusions were done with use of 1 K-wire, 20 with 2 (71.4 %), and 1 with 3 K-wires. The most common K-wire sizes were 1.1-inch (24 K-wires = 48 %), and 0.9 inch (21 K-wires = 42 %) The preoperative VAS score and quick DASH score improved from 6.1 (range: 0-9) and 25.8 (range: 2-38) to 0.4 (range: 0-2) and 3.4 (range: 0-10.2), respectively. 25 (89.3 %) out of 28 fingers achieved bony union in an average of 96.1 days (range: 58-114) with three non-union.

CONCLUSION

Arthrodesis of small DIPJs with K-wire fixation has a high success rate. Therefore, we suggest K-wire fixation as an acceptable alternative for patients with a small phalanx which may be at risk of mismatch with bigger implants. However, concerns remain in terms of fusion delay with K-wire only fixation.

[Arthrodesis of the distal interphalangeal Joint - a literature Review]

This review addresses the arthrodesis of the distal interphalangeal joint of the finger and the interphalangeal joint of the thumb with focus on indications, approaches, preparation of the articular surfaces, the angle of arthrodesis, advances and disadvantages of each technique, and postoperative care.

Investigating the origin of photoplethysmography using a multiwavelength Monte Carlo model

Photoplethysmography (PPG) is a photometric technique used for the measurement of volumetric changes in the blood. The recent interest in new applications of PPG has invigorated more fundamental research regarding the origin of the PPG waveform, which since its discovery in 1937, remains inconclusive. A handful of studies in the recent past have explored various hypotheses for the origin of PPG. These studies relate PPG to mechanical movement, red blood cell orientation or blood volume variations.

OBJECTIVE

Recognising the significance and need to corroborate a theory behind PPG formation, the present work rigorously investigates the origin of PPG based on a realistic model of light-tissue interactions.

APPROACH

A three-dimensional comprehensive Monte Carlo model of finger-PPG was developed and explored to quantify the optical entities pertinent to PPG (e.g. absorbance, reflectance, and penetration depth) as the functions of multiple wavelengths and source-detector separations. Complementary to the simulations, a pilot in vivo investigation was conducted on eight healthy volunteers. PPG signals were recorded using a custom-made multiwavelength sensor with an adjustable source-detector separation.

MAIN RESULTS

Simulated results illustrate the distribution of photon-tissue interactions in the reflectance PPG geometry. The depth-selective analysis quantifies the contributions of the dermal and subdermal tissue layers in the PPG wave formation. A strong negative correlation (r = -0.96) is found between the ratios of the simulated absorbances and measured PPG amplitudes.

SIGNIFICANCE

This work quantified for the first time the contributions of different tissue layers and sublayers in the formation of the PPG signal.

Arthrodesis of the digital joint using intraosseous wiring in patients with rheumatoid arthritis

OBJECTIVE

Digital joints affected by rheumatoid arthritis often have severe deformity and/or dislocation, and arthrodesis in a functional position is required.

METHODS

Arthrodesis was performed using intraosseous wiring (modified Lister's method) from January 2011 to December 2015, and we investigated the union rate, postoperative complications, and patient satisfaction with the operation at the final follow-up. The DASH score, grip power, and pinch power were also investigated before the operation and at the final follow-up.

RESULTS

Arthrodesis was performed for 90 digital joints in 56 patients. Bone union was obtained in 85 of 89 joints (96%). Wire removal was needed due to subcutaneous protrusion in 20 joints and superficial infection in five joints. The mean preoperative DASH score of 50.5 improved to 45.2 at the final follow-up. The pulp pinch power of the index fingers through the little fingers changed significantly. In the questionnaire regarding the operated digit using a visual analogue scale (VAS, 0 [worst] to 100 [best]), the overall satisfaction was 70.

CONCLUSION

With this approach, we achieved painless stability as well as deformity correction. A restored prehensile pattern and improvement in the activities of daily life can thus be expected after surgery.

Monte Carlo Analysis of Optical Interactions in Reflectance and Transmittance Finger Photoplethysmography

Photoplethysmography (PPG) is a non-invasive photometric technique that measures the volume changes in arterial blood. Recent studies have reported limitations in developing and optimising PPG-based sensing technologies due to unavailability of the fundamental information such as PPG-pathlength and penetration depth in a certain region of interest (ROI) in the human body. In this paper, a robust computational model of a dual wavelength PPG system was developed using Monte Carlo technique. A three-dimensional heterogeneous volume of a specific ROI (i.e., human finger) was exposed at the red (660 nm) and infrared (940 nm) wavelengths in the reflectance and transmittance modalities of PPG. The optical interactions with the individual pulsatile and non-pulsatile tissue-components were demonstrated and the optical parameters (e.g., pathlength, penetration depth, absorbance, reflectance and transmittance) were investigated. Results optimised the source-detector separation for a reflectance finger-PPG sensor. The analysis with the recorded absorbance, reflectance and transmittance confirmed the maximum and minimum impact of the dermis and bone tissue-layers, respectively, in the formation of a PPG signal. The results presented in the paper provide the necessary information to develop PPG-based transcutaneous sensors and to understand the origin of the ac and dc components of the PPG signal.

Distal interphalangeal joint arthrodesis with the intramedullary Lync® implant: Prospective study of 22 cases

Several techniques have been described for fusion of the distal interphalangeal joint. The intramedullary Lync^® implant (Novastep™) may be superior to other options as it is available in straight or bent configurations, does not need to be removed and does not require fingertip incisions. The objective of our prospective study was to determine the effectiveness of finger distal interphalangeal (DIP) arthrodesis with Lync^® implants. Between February 2016 and June 2017, we performed 22 cases of DIP arthrodesis with this implant. Pain was assessed with a visual analog scale, the joint range of motion was measured using a digital goniometer, the pulp to palm distance was measured using a ruler, and the QuickDASH Questionnaire was filled out. AP and lateral X-rays were used to look for secondary displacement at 3 weeks and joint fusion at 6 weeks, 3 months, 6 months and 12 months. The primary endpoint was clinical and radiological union defined as the presence of trabecular bone bridges across the arthrodesis site. The patients' mean age was 57.8 years ± 9.9 (36-73). The mean follow up was 10 months ± 4.9 (3-15). The pre-operative pain level was 6/10 ± 2.4 (0-10) and it was 1.3/10 ± 1.7 (0-6) at 3 months post-operative (P < 0.0001). The mean pre-operative DASH Score was 64/100 ± 16 (15.9-86.3) and it was 19/100 ± 14 (2.3-45.4) at 3 months post-operative (P < 0.0001). At the end of the study, 20 DIP joints were fused (91%); 18 joints had fused at the 3 month follow-up visit (82%). Three cases required reoperation. DIP arthrodesis with the Lync^® implant resulted in DIP fusion in 91% of cases. When fusion was achieved, it provided pain relief and improved function. The Lync^® implant is less bulky than other arthrodesis devices and does not need to be removed.

A two scale modeling and computational framework for vibration-induced Raynaud syndrome

Hand-Arm Vibration syndrome (HAVS), usually caused by long-term use of hand-held power tools, can in certain manifestations alter the peripheral blood circulation in the hand-arm region. HAVS typically occurs after exposure to cold, causing an abnormally strong vasoconstriction of blood vessels. A pathoanatomical mechanism suggests that a reduction of the lumen of the blood vessels in VWF (Vibration White Finger) subjects, due to either hypertrophy or thickening of the vessel wall, may be at the origin of the disease. However, the direct and indirect effects of the load of the hand-held tools on the structure of blood vessels remain controversial:.one hypothesis is the mechanical action of vibration on the local acral dysregulation and/or on the vessel histomorphological modifications. Another hypothesis is the participation of the sympathetic nervous system to this dysregulation. In this paper, we assume the modifications as mechanobiological growth and the load-effect relationship may be interpreted as directly or indirectly induced. This work is the first attempt to model the effect of vibration through soft tissues onto the distal capillaries, addressing the double paradigm of multi space-time scales, i.e. low period vibration versus high time constant of the growth phenomenon as well as vibrations propagating in the macroscopic tissue including the microscopic capillary structures subjected to a pathological microstructural evolution. The objective is to lay down the theoretical basis of growth modeling for the small distal artery, with the ability to predict the geometrical and structural changes of the arterial walls caused by vibration exposure. We adopt the key idea of splitting the problem into one global vibration problem at the macroscopic scale and one local growth problem at the micro level. The macroscopic hyperelastic viscous dynamic model of the fingertip cross-section is validated by fitting experimental data. It is then used in steady-state vibration conditions to predict the mechanical fields in the close vicinity of capillaries. The space scale transfer from macroscopic to microscopic levels is ensured by considering a representative volume element (RVE) embedding a single capillary in its center. The vibrations emitted by the hand held power tool are next linked to the capillary growth through the adopted biomechanical growth model at the capillary level. The obtained results show that vibrations induce an increase of the thickness of the capillary's wall, thereby confirming the scenario of vibrations induced reduction of the lumen of blood vessels.

Individual headless compression screws fixed with three-dimensional image processing technology improves fusion rates of isolated talonavicular arthrodesis

BACKGROUND

Screw fixation is a typical technique for isolated talonavicular arthrodesis (TNA), however, no consensus has been reached on how to select most suitable inserted position and direction. The study aimed to present a new fixation technique and to evaluate the clinical outcome of individual headless compression screws (HCSs) applied with three-dimensional (3D) image processing technology to isolated TNA.

METHODS

From 2007 to 2014, 69 patients underwent isolated TNA by using double Acutrak HCSs. The preoperative three-dimensional (3D) insertion model of double HCSs was applied by Mimics, Catia, and SolidWorks reconstruction software. One HCS oriented antegradely from the edge of dorsal navicular tail where intersected interspace between the first and the second cuneiform into the talus body along the talus axis, and the other one paralleled the first screw oriented from the dorsal-medial navicular where intersected at the medial plane of the first cuneiform. The anteroposterior and lateral X-ray examinations certified that the double HCSs were placed along the longitudinal axis of the talus. Postoperative assessment included the American Orthopaedic Foot & Ankle Society hindfoot (AOFAS), the visual analogue scale (VAS) score, satisfaction score, imaging assessments, and complications.

RESULTS

At the mean 44-months follow-up, all patients exhibited good articular congruity and solid bone fusion at an average of 11.26 ± 0.85 weeks (range, 10 ~ 13 weeks) without screw loosening, shifting, or breakage. The overall fusion rates were 100%. The average AOFAS score increased from 46.62 ± 4.6 (range, 37 ~ 56) preoperatively to 74.77 ± 5.4 (range, 64-88) at the final follow-up (95% CI: -30.86 ~ -27.34; p < 0.001). The mean VAS score decreased from 7.01 ± 1.2 (range, 4 ~ 9) to 1.93 ± 1.3 (range, 0 ~ 4) (95% CI: 4.69 ~ 5.48; p < 0.001). One cases (1.45%) and three cases (4.35%) experienced wound infection and adjacent arthritis respectively. The postoperative satisfaction score including pain relief, activities of daily living, and return to recreational activities were good to excellent in 62 (89.9%) cases.

CONCLUSIONS

Individual 3D reconstruction of HCSs insertion model can be designed with three-dimensional image processing technology in TNA. The technology is safe, effective, and reliable to isolated TNA method with high bone fusion rates, low incidences of complications.

Modeling of diffuse reflectance of light in heterogeneous biological tissue to analysis of the effects of multiple scattering on reflectance pulse oximetry

Fingertip-type pulse oximeters are popular, but their inconvenience for long-term monitoring in daily life means that other types of wearable pulse oximeters, such as reflectance pulse oximeters, need to be developed. For the purpose of developing reflection pulse oximetry, we have analyzed the light propagation in tissue to calculate and estimate the measured intensities of reflected light using the analytical and numerical solutions of the diffusion approximation equation. The reflectance of light from the biological tissue is investigated from theoretical and experimental perspectives, for light in the visible and near-infrared wavelengths. To establish the model, the calculated curves were compared with the analytical solution (AS) of the diffusion approximation equation in biological tissue. The results validated that the diffusion approximation equation could resolve the heterogeneous advanced tissue and the finite element method (FEM) could offer the simulation with higher efficiency and accuracy. Our aim has been to demonstrate the power of the FEM and AS in modeling of the steady-state diffusion approximation in a heterogeneous medium. Also, experimental data and the Monte Carlo model as a gold standard were used to verify the effectiveness of these methods.