Treatment of patella fracture by claw-like shape memory alloy

Research progress on surface modification and coating technologies of biomedical NiTi alloys

NiTi alloys are an important class of biomaterials with extensive clinical applications such as cardiovascular stents, orthodontic arch-wires, esophageal stents, orthopedic implants and more. However, the long-term implantation of NiTi alloys presents significant challenges due to their susceptibility to wear, corrosion and the excessive release of harmful nickel ions. These factors can severely compromise both the biocompatibility and the overall service life of the implants. To better meet the demands for safety, durability and superior biological performance after implantation, surface modification of NiTi alloys has become a focal point of current research. Based on the fundamental properties of the NiTi alloys and the challenges encountered in their practical applications, this article provides a focused review of recent advances in improving their corrosion resistance, wear resistance, antibacterial properties and biological performance through surface modification and coating techniques. In addition, the paper outlines current research challenges and proposes recommendations for future development directions.

Nanotechnology-Assisted mesenchymal stem cells treatment for improved cartilage regeneration: A review of current practices

Cartilage tissue does not promptly elicit an inflammatory response upon injury, hence constraining its capacity for healing and self-regeneration. Mesenchymal Stem Cells (MSC) therapy, enhanced by nanotechnology, offers promising advancements in cartilage repair. Injuries to cartilage often cause chronic pain, where current treatments are inadequate. As MSCs can readily differentiate into chondrocytes and secrete soluble factors, they are essential components in tissue engineering of cartilage repair. Although, like other stem cell applications, clinical applications are restricted by poor post implantation survival and differentiation. Recent studies show that nanoparticles (NPs) can further improve MSC outcomes by promoting cell adhesion, and chondrogenic differentiation allowing for sustained growth factor release. In addition, nanomaterials can improve the biological activity of MSCs, by also facilitating the composition of a conducive microenvironment for cartilage repair. In this review, the application of nanofibrous scaffolds, hydrogels and nanoscale particulate matter to improve mechanical properties in cartilage tissue engineering, are discussed. Moreover, the MSCs and nanotechnology synergistic effects present hope of overcoming the limitations of conventional treatments. Nanotechnology greatly enhances the MSC based cartilage regeneration strategies and could provide better treatment for cartilage related diseases in the future. Future research should be aimed at standardizing MSC harvesting and culturing protocols and contrasting their long-term efficacy.

Targeting the tumor microenvironment with mesenchymal stem cells based delivery approach for efficient delivery of anticancer agents: An updated review

Drug delivery to cancer cells continues to present a major therapeutic challenge. Mesenchymal stem cells (MSCs) possess an intrinsic ability to migrate specifically to tumor tissues, making them promising candidates for targeted drug delivery. Evidence from preclinical studies indicates that MSCs loaded with therapeutic anti-cancer agents exhibit considerable anti-tumor activity. Moreover, several clinical trials are currently evaluating their effectiveness in cancer patients. The integration of MSCs with synthetic nanoparticles (NPs) enhances their therapeutic potential, particularly through the use of cell membrane-coated NPs, which represent a significant advancement in the field. This review systematically investigates the tumor microenvironment, the sources of MSCs, the tumor homing mechanisms, and the methods of loading and releasing anticancer drugs from MSCs. Furthermore, cutting-edge strategies to improve the efficacy of MSCs based drug delivery systems (DDS) including the innovative use of MSC membrane coated nanoparticles have been discussed. The study concludes with an overview of the therapeutic use of MSCs as drug carriers, including a detailed analysis of the mechanisms by which MSCs deliver therapeutics to cancer cells, enabling targeted drug delivery. It aims to elucidate the current state of this approach, identify key areas for development, and outline potential future directions for advancing MSCs based cancer therapies.

An innovative anti-rotation tension band wiring for treating transverse patellar fractures: finite element analysis and mechanical testing

BACKGROUND

The displacement and rotation of the Kirschner wire (K-wire) in the traditional tension band wiring (TBW) led to a high rate of postoperative complications. The anti-rotation tension band wiring (ARTBW) could address these issues and achieve satisfactory clinical outcomes. This study aimed to investigate the biomechanical performance of the ARTBW in treating transverse patellar fracture compared to traditional TBW using finite element analysis (FEA) and mechanical testing.

METHODS

We conducted a FEA to evaluate the biomechanical performance of traditional TBW and ARTBW at knee flexion angles of 20°, 45°, and 90°. Furthermore, we compared the mechanical properties under a 45° knee flexion through static tensile tests and dynamic fatigue testing. The K-wire pull-out test was also conducted to evaluate the bonding strength between K-wires and cancellous bone of two surgical approaches.

RESULTS

The outcome of FEA demonstrated the compression force on the articular surface of ARTBW was 28.11%, 27.32%, and 52.86% higher than traditional TBW at knee flexion angles of 20°, 45°, and 90°, respectively. In mechanical testing, the mechanical properties of ARTBW were similar to the traditional TBW. In the K-wire pull-out test, the pull-out strength of ARTBW was significantly greater than the traditional TBW (111.58 ± 2.38 N vs. 64.71 ± 4.22 N, P < 0.001).

CONCLUSIONS

The ARTBW retained the advantages of traditional TBW, and achieved greater compression force of articular surface, and greater pull-out strength of K-wires. Moreover, ARTBW effectively avoided the rotation of the K-wires. Therefore, ARTBW demonstrates potential as a promising technique for treating patellar fractures.

Transverse patella fracture fixation: A cadaveric biomechanical comparison of cannulated screws and anterior tension band versus low-profile, multiplanar mesh plating

INTRODUCTION

Multiplanar mesh plating of patella fractures has become more popular in recent years. It was the goal of this study to compare the biomechanical stability of cannulated screw with anterior tension band to multiplanar mesh plating for fixation of transverse patella fractures in cadaver specimens.

MATERIALS AND METHODS

Eight matched pairs of fresh frozen cadaveric knees were obtained and soft tissues dissected leaving the extensor mechanism, joint capsule, and retinaculum intact. Transverse fractures were created at the mid-portion of the patella. For each pair, one specimen was repaired using cannulated screws with anterior tension band, and the second was repaired using multiplanar mesh plating. Each specimen underwent cyclic extension loading with loads increasing by 1.1 kg after every 50 cycles. Interfragmentary displacement was measured at the end of each interval at both 5° and 45° of knee flexion angle, with fixation failure defined by >2 mm displacement.

RESULTS

The specimens fixed with multiplanar mesh plating survived more cycles and higher loads than the specimens fixed with cannulated screws with anterior tension band (p = 0.011 comparing survival plots). After 150 cycles of extension loading, 3 of 8 of the specimens fixed with screws/tension band had failed, whereas none of the mesh plated specimens had failed. After 400 cycles, 7 of 8 of the screws/tension band had failed, whereas half of the mesh plated specimens had failed.

CONCLUSIONS

While a more technically challenging and expensive technique, mesh plating for patella fractures appears to offer greater durability than traditional cannulated screw with tension banding.

Multifunctional coatings of nickel-titanium implant toward promote osseointegration after operation of bone tumor and clinical application: a review

Metal implants, especially Ni-Ti shape memory alloy (Ni-Ti SMA) implants, have increasingly become the first choice for fracture and massive bone defects after orthopedic bone tumor surgery. In this paper, the internal composition and shape memory properties of Ni-Ti shape memory alloy were studied. In addition, the effects of porous Ni-Ti SMA on osseointegration, and the effects of surface hydrophobicity and hydrophilicity on the osseointegration of Ni-Ti implants were also investigated. In addition, the effect of surface coating modification technology of Ni-Ti shape memory alloy on bone bonding was also studied. Several kinds of Ni-Ti alloy implants commonly used in orthopedic clinic and their advantages and disadvantages were introduced. The surface changes of Ni-Ti alloy implants promote bone fusion, enhance the adhesion of red blood cells and platelets, promote local tissue regeneration and fracture healing. In the field of orthopaedics, the use of Ni-Ti shape memory alloy implants significantly promoted clinical development. Due to the introduction of the coating, the osseointegration and biocompatibility of the implant surface have been enhanced, and the success rate of the implant has been greatly improved.

Research and Application of Medical Polyetheretherketone as Bone Repair Material

Polyetheretherketone (PEEK) can potentially be used for bone repair because its elastic modulus is similar to that of human natural bone and good biocompatibility and chemical stability. However, its hydrophobicity and biological inertness limit its application in the biomedical field. Inspired by the composition, structure, and function of bone tissue, many strategies are proposed to change the structure and functionality of the PEEK surface. In this review, the applications of PEEK in bone repair and the optimization strategy for PEEK's biological activity are reviewed, which provides a direction for the development of multifunctional bone repair materials in the future.

Treating Inferior Pole Fracture of Patella with Hand Plating System: First Clinical Results

OBJECTIVE

Inferior pole fractures of patella are notorious fractures where it is difficult to obtain rigid internal fixation by conventional methods. The objective of the study was to introduce the Hand Plating System (HPS), which was a novel surgical technique for inferior pole fractures of patella, and to report the radiological and clinical outcomes following the application of the surgical technique.

METHODS

The study was designed as a retrospective cohort study. Between July 2017 and December 2018, 30 patients who were diagnosed with inferior pole fracture of the patella without additional orthopaedic injuries were enrolled in this case series. After X-ray and 3D-CT examinations, all patients underwent open reduction and internal fixation by HPS with or without supplementary cannulated screw and lag screw stabilization. The bony union time, final range of motion (ROM), Bostman score, visual analog scale (VAS), and complications were measured as the clinical outcomes under a minimum of 12 months of follow-up.

RESULTS

All of the operations went well with the mean operative time of 76.2 ± 15.3 min. Bony union achieved in all the cases at an average of 9.5 ± 1.4 weeks after surgery. There was no loss of reduction, fixative failure, or surgical implant removal during follow-up. The average range of motion 1 year postoperatively was 0°-123.3°. The mean Bostman Score at the last follow-up was 26.8 ± 2.1 with the satisfactory rate of 100%. The pain feeling during walking as measured by VAS averaged at 0.9 ± 1.3. No complications developed except for one case of poor incision healing, which healed eventually after surgical debridement.

CONCLUSIONS

HPS was demonstrated as a secure fixation and as a kind of tension band for inferior pole fractures of the patella. Satisfactory recovery of knee function and low complication rate, including no need for hardware removal, could be expected.

Mechanical Analysis and Clinical Application of Butterfly-Shaped Patellar Claw

Memory alloy patella claws for treating patella fractures have been used for more than 30 years with many desirable features including fast healing, quick recovery, and avoidance of top abrasion of Kirschner wires and other complications. However, there are many models and it is difficult to choose the accurate claw for the patient. In this study, a finite element model of the butterfly-shaped patellar claw made of shape memory alloy was established, its mechanical structure was analyzed, and its clinical application was monitored. We used Solidworks Simulation software for modeling and mainly analyzed the force of the compression ring of the butterfly-shaped patellar claw. Clinically, we chose a closed fresh patella fracture case. After finite element analysis, the maximum stress that the compression ring of the butterfly-shaped patellar claw can withstand is 568.1 MPa. In this range, it always has elastic deformation resistance. The butterfly-shaped patella claw is fixed on the patella and will not break when subjected to a maximum force of 150 N on the encircling arm, and at the same time, there will be no pressure failure due to plastic deformation. A total of 27 cases were clinically used for the assessment of the clinical efficacy of the newly designed butterfly-shaped patella claws. The average follow-up time was 15.5 months, and the average fracture healing time was 8-12 weeks. All patients can get out of bed with crutches within 2 to 3 days after surgery. Among them, there were 15 cases with excellent functional ratings, 10 cases with good ratings, 2 cases with acceptable ratings, and no cases with poor ratings. The designed butterfly-shaped patella claws can provide an effective method for the treatment of patella fractures.

Functional Outcomes of Patella Fractures Treated With Anterior Plate Osteosynthesis at One Year

OBJECTIVES

To evaluate the functional outcomes of patients with displaced patellar fractures treated with anterior plate constructs.

DESIGN

Prospective cohort and retrospective clinical and radiographic assessment.

SETTING

Level I Trauma Center.

PATIENTS/PARTICIPANTS

Between 2014 and 2018, 18 patients who underwent operative intervention for an isolated, displaced patella fracture (OTA/AO 34C1-3) with a minimum of 1-year follow-up agreed to participate in the study. The mean follow-up was 19.5 ± 6.0 months.

INTERVENTION

Patients were treated with 2.4 or 2.7-mm plates and supplemental screws or cerclage wires.

MAIN OUTCOME MEASUREMENTS

Patients were evaluated with the Short Form-36 Survey and the Knee Injury and Osteoarthritis Outcome Scores and asked about symptomatic implants. The range of motion was assessed by goniometer.

RESULTS

The cohort had no wound complications, infections, nonunion, loss of reduction, or implant failure. Active knee flexion was 131 ± 7 degrees. Five patients (28%) endorsed implant irritation. Only one patient (5.5%) underwent implant removal, which consisted of transverse screw removal alone. Twelve of the 14 patients (86%), who were previously employed, returned to work at 10 ± 7 weeks. All Knee Injury and Osteoarthritis Outcome Scores subscale scores and the Short Form-36 Survey scores for physical functioning, limitations due to physical health, limitations due to mental health, and social functioning were significantly lower than reference population norms (P < 0.05).

CONCLUSIONS

Anterior plating provides reliable fixation for displaced patellar fractures and results in a low incidence of implant irritation. However, patients who had anterior fixation for displaced patella fractures continue to exhibit functional deficits at 1-year postoperatively.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Fiber Laser Surface Melting of a NiTi Superelastic Alloy: Influence on Structural and Mechanical Properties

The surface melting of a NiTi superelastic alloy using a high-power laser Yb:Fiber was investigated. The influence of this process on the microstructural and mechanical properties was also examined. The reference material was a 3 mm nitinol strip with a homogeneous austenitic B2 phase. For the laser surface melting process, input fluences were applied from 17.5 to 45 J/mm2. The morphology of the structure and the chemical composition of several regions were determined by optical microscopy, scanning electron microscopy, dispersive energy spectra, and X-ray diffraction techniques. The mechanical properties, such as modulus of elasticity and hardness, were determined using nanoindentation and microindentation techniques. The greatest surface finishing of the fusion zone was observed for the condition 35 J/mm2. Three well-defined regions (fusion zone (FZ), heat-affected zone (HAZ), base metal (BM)) could be observed and dimensions of grain size, width, and depth of the melted pool were directly affected by the laser fluence. The geometry of the molten pool could be controlled by the optimization of the laser parameters. High laser fluence caused preferential volatilization of nickel, dynamic precipitation of intermetallic phases, including Ti2Ni, Ni3Ti, and Ni4Ti3, as well as solubilization of TiC in the matrix, which led to grain refinement. Thus, high laser fluence is a suitable technique to enhance mechanical properties such as hardness and Young’s modulus.

Treatment of Patella Fractures

Patella fractures comprise 1% of all fractures. Treatment options vary based on fracture displacement, classification, and patient factors. Traditionally, nonoperative treatment has been reserved for nondisplaced fractures. Many operative treatments are available with differing indications and levels of success. Tension band constructs have been the most commonly employed approach to fixation, with cerclage wiring for comminuted fractures. Recently, plate fixation of patella fractures has become more popular. Plating constructs offer a low-profile design with stable fixation, allowing for earlier mobilization and potentially improved functional outcomes. Data regarding the long-term outcomes of plating techniques are limited, and further studies are needed. [Orthopedics. 2018; 41(6):e747-e755.].

Five-pointed star lattice sutures for fixation of patella transverse fractures: a clinical study

INTRODUCTION

Fixation of displaced patella fractures with metal implants may be associated with implant failure, post-operative pain, and high re-operation rate. This study reports preliminary clinical results of using five-pointed star lattice sutures for the management of patella transverse fractures.

METHODS

A five-pointed star lattice suture configuration was produced intraoperatively, and 25 patients with patella transverse fractures were treated with this newly designed sutures fixation. All patients were followed up until union of the fractures or until further surgical intervention. At a mean of 1.6 years (range 0.8-2.5 years) of follow-up, the notes and plain radiographs of the 25 patients were reviewed. Bostman score was used to evaluate the therapeutic effects.

RESULTS

All 25 patients experienced union of the patella fractures, with excellent knee function in 19 patients and good in 6 patients evaluated with Bostman score.

CONCLUSION

The newly designed five-pointed star lattice sutures fixation may be a feasible alternative to metal implants fixation in the management of patella transverse fracture.

LEVEL OF EVIDENCE

Level IV case series.

Surgery of patellar fractures using a medial parapatellar approach

PURPOSE

The general surgical approach for patellar fractures has a significant weakness, in that the articular facet is invisible because the fixation is performed using radiation amplifiers after exposing the fracture site through vertical or transverse dissection on the anterior patella. We report excellent outcomes in the surgical treatment of patellar fractures, using a medial parapatellar approach.

METHODS

This study evaluated 20 patients who underwent surgery between August 2008 and April 2014 to correct patellar fractures with comminution or with displacement of the articular facet of ≥2 mm and who had ≥1 year of follow-up. Surgery was performed using anatomical reduction with direct exposure of the articular facet of the patella via a medial parapatellar approach. Bone union, severity of displacement, range of motion (ROM) of the patella, and complications were evaluated after surgery, and patellar function was evaluated using the Lysholm knee score.

RESULTS

Bone union was achieved in all cases, and average displacement of the articular facet decreased from 3.2 mm (range: 1.2-7.3 mm) preoperatively to 0.2 mm (range: 0-0.5 mm) postoperatively. No particular postsurgical complication was observed. All cases had a normal ROM, and the average Lysholm score at final follow-up was 96.2 points.

CONCLUSION

Anatomical fixation of the articular facet via a medial parapatellar approach appears to be suitable for patellar fractures, which are intra-articular.

Comminuted Patella Fracture in Elderly Patients: A Systematic Review and Case Report

Objectives:

To review comminuted patella fracture in the elderly patients and examine the surgical options to avoid complications such as fixation failure and poor functional outcome. To provide an example of mesh augmentation in comminuted patella fracture in the elderly patients.

Data Sources:

A literature review was conducted by the authors independently using Ovid, Medline, Cochrane, PubMed, and Clinical Key in English. We aimed to review data on patients older than 65 with comminuted patella fracture. Search conducted between July and December 2015.

Study Selection:

Search terms included patella fracture, elderly, and fixation failure. Abstracts were included if they were a case report, cohort series, or randomized control trial. Further inclusion criteria were that they were available in full text and included patient age(s), operative details, follow-up, and outcome discussion.

Data Extraction:

Each study was assessed according to its level of evidence, number of patients, age of patients, fracture patterns described, complications of treatment, and results summarized.

Data Synthesis:

Paucity of data and heterogeneity of studies limited statistical analysis. Data are presented as a review table with the key points summarized.

Conclusion:

In patella fracture, age >65 years and comminuted fracture pattern are predictors of increased fixation failure and postoperative stiffness, warranting special consideration. There is a trend toward improved functional outcomes when augmented fixation using mesh or plates is used in this group. Further level 1 studies are required to compare and validate new treatment options and compared them to standard surgical technique of tension band wire construct.

Superior Outcomes After Operative Fixation of Patella Fractures Using a Novel Plating Technique: A Prospective Cohort Study

OBJECTIVE

The purpose of this prospective cohort study was to determine if a new patella fracture fixation construct resulted in improved outcomes compared with traditional tension band techniques.

DESIGN

Comparative cohort study.

SETTING

Academic level I trauma center.

PATIENTS/PARTICIPANTS

Patients with isolated, unilateral patellar fractures were enrolled prospectively. From 2012 to 2014, 33 patients underwent fixation with a novel plate construct that spans half of the patella circumference laterally and provides multiplanar fixation through a low-profile plate. A comparison cohort was drawn from 25 patients treated from 2008 to 2012, where treatment consisted of traditional tension band fixation techniques.

INTERVENTION

Surgical fixation of patella fractures was performed with either a tension band or novel plate construct.

MAIN OUTCOME MEASUREMENTS

Subjective postoperative clinical outcomes and objective functional and strength measurements were subsequently collected.

RESULTS

The 2 cohorts had similar baseline characteristics. Patients with the plate construct had clinically and statistically significantly superior Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS) scores throughout the study period (P < 0.001). Functional testing also demonstrated significant improvements in patients with plate constructs compared with tension band constructs at 12 months. Patients in the plate cohort had significantly increased thigh circumferences (P = 0.003) and decreased anterior knee pain (P < 0.0001) compared with the tension band cohort.

CONCLUSIONS

In this prospective cohort study, the use of a novel fixation construct with multiplanar and interfragmentary fixation and minimal disruption of patellar vascularity enables improved clinical outcomes and functional performance.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.