Effect of wire electro discharge machining process parameters on surface integrity of Ti49.4Ni50.6 shape memory alloy for orthopedic implant application

Ti_49.4Ni_50.6 (atomic %) shape memory alloy (SMA) is a unique class of smart materials because of its unbeatable property. It plays a very important role in the construction of novel orthopedic implants, because of its lower Young's modulus compared to other biomedical implant materials, Conventional machining of Ti-Ni yields poor surface finish and low dimensional accuracy of the machined components. Wire electro-discharge machining (WEDM) can achieve high dimensional accuracy, but its thermal nature causes great concern regarding surface integrity for biocompatibility application of Ti-Ni material. Therefore, it is necessary to investigate the surface morphology and non-toxic, non-hazardous surface conductive to the human body. Hence, WEDM of Ti-Ni can be used. Shape memory effect (SME) of SMA was achieved by subsequent heat treatment processes which include annealing followed by ageing. For manufacturing the Ti-Ni implants, a WEDM optimized process has been used and various performance attributes such as material removal rate (MRR), surface roughness (SR), surface topography, metallurgical changes, recast layer, micro-hardness, residual stresses and shape recovery ability of the machined components have been evaluated, so as to obtain high biocompatibility of machined surface. The minimum surface roughness with consistency, suitable surface integrity parameters like less deposition of material, minimum recast layers thickness, consentaneous amount of surface hardness and less affecting subsurface residual stresses have been determined for validated experiment with an increase in wire feed. MRR increases with increase in wire feed. SR decreases with increase in wire feed due to enhanced splashing of molten material. Shape recovery ability near wire electro-discharge machined surface has been investigated from the biocompatible point of view. Heat treatment like annealing is found to be the most suitable process to recover shape memory effect of WEDMed samples.

Comparison of implant failure rates of different plates for midshaft clavicular fractures based on fracture classifications

Backgrounds

The aim of our study was to investigate failure rates of reconstruction plate and non-reconstruction plate, and find the best strategy for implant selection for different fracture types for midshaft clavicular fractures.

Patients and methods

Two hundred twenty-six consecutive patients with midshaft clavicular fractures who received open reduction and plate fixation during Jan 2012 to July 2017 were reviewed. The correlations between implant failure rates and risk factors including demographic data, fracture classifications, and implant types were analyzed.

Results

AO/OTA fracture classification and plate types are the most important factors affecting implant failure for midshaft clavicular fractures. Reconstruction plate had a significantly higher failure rate (53%) than that of non-reconstruction plates (3%) in comminuted midshaft clavicular (AO/OTA 15-2C) fractures (P value < 0.01). However, the difference was not significant in AO/OTA 15-2A and 2B classifications.

Conclusion

Patients with comminuted midshaft clavicular (AO/OTA 15-2C) fractures treated with reconstruction plates had very high implant failure rates compared to non-reconstruction plates. We suggested that patients with comminuted midshaft clavicular (AO/OTA 15-2C) fractures treated with reconstruction plates need more protection and more frequent follow-up in the postoperative period.

A biomechanical comparison of conventional dynamic compression plates and string-of-pearls™ locking plates using cantilever bending in a canine Ilial fracture model

Background

Fracture of the ilium is common orthopedic injury that often requires surgical stabilization in canine patients. Of the various methods of surgical stabilization available, application of a lateral bone plate to the ilium is the most common method of fixation. Many plating options are available, each having its own advantages and disadvantages. The purpose of this study was to evaluate the biomechanical properties of a 3.5 mm String-of-Pearls™ plate and a 3.5 mm dynamic compression plate in a cadaveric canine ilial fracture model. Hemipelves were tested in cantilever bending to failure and construct stiffness, yield load, displacement at yield, ultimate load, and mode of failure were compared.

Results

The mean stiffness of dynamic compression plate (116 ± 47 N/mm) and String-of-Pearls™ plate (107 ± 18 N/mm) constructs, mean yield load of dynamic compression plate (793 ± 333 N) and String-of-Pearls™ plate (860 ± 207 N) constructs, mean displacement at yield of dynamic compression plate (8.6 ± 3.0 mm) and String-of-Pearls™ plate (10.2 ± 2.8 mm) constructs, and ultimate load at failure of dynamic compression plate (936 ± 320 N) and String-of-Pearls™ plate (939 ± 191 N) constructs were not significantly different. No differences were found between constructs with respect to mode of failure.

Conclusions

No significant biomechanical differences were found between String-of-Pearls™ plate and dynamic compression plate constructs in this simplified cadaveric canine ilial fracture model.

Two reconstruction plates provide superior stability of displaced midshaft clavicle fractures in comparison to single plating - A biomechanical study

BACKGROUND

Displaced midshaft fractures are the most common surgically treated clavicle fractures. However, they are associated with high complication rates following plating due to fixation failure in terms of plate breakage, screw breakage and/or screw loosening. The aim of this study was to compare the biomechanical competence of three different plating techniques for fixation of displaced midshaft clavicle fractures.

METHODS

Displaced midshaft fractures type 2B according to the Robinson classification were simulated by standardized osteotomy gap in 18 synthetic clavicles, assigned to three groups (n = 6) for plating with either superiorly placed Dynamic Compression Plate (width/thickness 11.0/4.0 mm), locked Superior Anterior Clavicle Locking Compression Plate (width/thickness 10.2/2.0 mm), or two non-locked Reconstruction Plates placed superiorly and anteriorly (width/thickness 10.0/2.8 mm). Each specimen was cyclically tested at 3 Hz under craniocaudal cantilever bending, superimposed with torsion around the shaft axis over 720'000 cycles or until failure occurred. The latter was defined by plate breakage, screw breakage or screw loosening.

FINDINGS

Initial construct stiffness (N/mm) and cycles to failure in group Reconstruction Plates (22.30 ± 4.07; 712'778 ± 17'691) were significantly higher compared with both groups Compression Plate (12.53 ± 2.09; 348'541 ± 212'941) and Locking Plate (4.19 ± 0.46; 19'536 ± 3'586), p ≤ 0.019. In addition, these two outcomes were significantly higher in group Compression Plate versus Locking Plate, p ≤ 0.029.

INTERPRETATION

Double plating of unstable midshaft clavicle fractures with reconstruction plates seems to provide superior fixation stability under dynamic loading, when compared to single compression or locked plating, whereas the latter is associated with inferior performance.

Clinical Outcome of Treatment of Diaphyseal Fractures of Humerus Treated by Titanium Elastic Nails in Adult Age Group

INTRODUCTION

Humerus shaft fracture is one of the most common injuries to the musculoskeletal system, which are managed both conservatively and surgically. There are pitfalls, advantages and disadvantages in each method. The individual fracture analysis determines the therapeutic options.

AIM

To assess the clinical outcome of treatment of diaphyseal fractures of humerus treated by Titanium elastic nail in adult age group by DASH scoring.

MATERIALS AND METHODS

It was a prospective study of 20 cases of diaphyseal fracture of humerus admitted to Era's Lucknow Medical College and Hospital between October 2014 and September 2015 treated with close reduction and internal fixation with titanium elastic nail. Functional outcome was evaluated using DASH scoring system and radiological outcome was evaluated by serial radiographs. The data was processed with SPSS software version 16.0 (Chicago, inc. USA) and it was summarized in proportion and percentage.

RESULTS

In our series of 20 patients, 17 were males and three were females. Most of the patients were between 30-50 years of age (mean 38 years). Most common mode of injury, side of involvement, level of fracture and fracture type were road traffic accidents (60%), right side (53.3%) and mid one third (75%), transverse (60%) respectively. So, in 65% of the patients, there was no disability of arm shoulder and hand as DASH score was within normal range and in 15% of the patients the disability was mild to moderate as scoring was slightly higher than normal and in 20% the disability was severe as the DASH score could not be calculated because of non union.

CONCLUSION

Elastic nail fixation require very minimal soft tissue dissection and being a close reduction, the biology of the fracture is also not disturbed and the chances of nerve injury are much less and as the non union was seen in oblique and spiral fracture type hence it should be used with caution or else other alternative methods of fixation should be used.

Are proximal screws necessary for osteosynthesis of stable-stem periprosthetic femoral fractures fixed with non-locking plate and cable?

INTRODUCTION

The purpose of this study was to assess the effectiveness of the cable-plate-cable technique which comprises fixation of the proximal fragment using cable loops without additional proximal screws on the plate for the treatment of stable-stem periprosthetic femoral fractures around hip prostheses.

METHODS

We retrospectively reviewed Vancouver types B1 and C periprosthetic femoral fractures treated with a dynamic compression plate combined with Dall-Miles cable between 2010 and 2016 at a single institution and followed for at least 12 months. Patients were treated with proximal fragment fixation using cable combined with screws (Group I) or with proximal fragment fixation using cable alone (Group II). Demographic data, fracture types, and clinical and radiological outcomes were analyzed.

RESULTS

A total of 50 patients were included (Group I, n = 23 patients; Group II, n = 27). Fracture union was achieved in 49 patients with one case of non-union in Group I and no cases of non-union in Group II. Mean time to union was 5.4 months in Group I and 5.1 months in Group II (P = 0.624). Mean Harris hip score at latest assessment was 69.5 in Group I and 69.4 in Group II (P = 0.919). Regarding complications, there was one deep wound infection, one stem subsidence, and one loss of reduction in Group I, and one stem subsidence in Group II. No significant difference in clinical and radiological outcomes between groups was observed.

CONCLUSIONS

The cable-plate-cable technique sufficiently treats Vancouver types B1 and C periprosthetic femoral fractures without use of additional screws in the proximal fragment.

Bilateral symmetrical pronation type of Galeazzi fracture following high-speed motor traffic crash: A case report

INTRODUCTION AND IMPORTANCE

Bilateral Galeazzi fracture is a rare occurrence following trauma. Anatomical reduction of the fracture and the distal radioulnar joint is mandatory for a good outcome.

CASE PRESENTATION

We present a 24-year-old patient with bilateral Galeazzi fracture following a high-velocity motorbike accident.

CLINICAL DISCUSSION

A motorcyclist presented with bilateral painful deformed forearms following a motor traffic crash. Radiographs of bilateral forearms showed bilateral symmetrical supination type (Type II) Galeazzi fractures. He has undergone open reduction and internal fixation of the bilateral radii. Bilateral distal radioulnar joints reduced spontaneously when the fracture of the radius reduced anatomically. The reduction of the fracture and the distal radioulnar joints was confirmed by postoperative radiographs.

CONCLUSION

Bilateral Galeazzi fracture is a rare entity following high-velocity injury. Disruption of the distal radial ulnar joint needs to address to achieve a good outcome. An awareness of this entity, early detection, and intervention of this condition may help to regain the full function of the forearm.

Higher nonunion rates with locking plates compared to dynamic compression plates in forearm diaphyseal fractures: a multicenter study

BACKGROUND

Dynamic compression plate (DCP) osteosynthesis is the gold standard for treating forearm diaphyseal fractures, providing stability and promoting healing. Locking plates (LPs) are increasingly used in modern fracture management but may increase the risk of nonunion if applied with excessive rigidity and without proper fracture site compression. The purpose of this study is to compare the nonunion rate between LPs and DCPs.

MATERIALS AND METHODS

We conducted a retrospective study by reviewing the medical records and radiographs of 515 patients diagnosed with radial and/or ulnar shaft fractures at three trauma centers between 2014 and 2019. Inclusion criteria were patients treated with locking plates (LPs), locking compression plates (LCPs), or dynamic compression plates (DCPs) who had at least 9 months of outpatient follow-up and imaging assessments. Exclusion criteria included treatment with other methods, hospitalization for pathological fractures or implant removal, or incomplete surgical records. Data on patient demographics, injury details, and surgical outcomes were collected to compare nonunion rates, as well as early and late complications, between the LP and DCP groups.

RESULTS

A total of 368 patients were included in the analysis. Among them, 132 (35.9%) had isolated radial shaft fractures, 116 (31.5%) had isolated ulnar shaft fractures, and 120 (32.6%) had both-bone fractures. Of these, 124 patients received LP implants, 98 were treated with LCPs, and 146 were treated with DCPs. Early complications were comparable among the groups; however, the nonunion rate was significantly higher in the LP group (18.5% versus 11.2% versus 6.2%, p < 0.007). Logistic regression identified LP use [odds ratio (OR): 3.05, 95% confidence interval (CI) 1.24-7.53] as a significant predictor of nonunion. Notably, LPs lacking dynamic compression functionality were associated with markedly higher odds of nonunion in radial shaft fractures (OR: 26.94, 95% CI 3.52-206.15). These findings collectively indicate that LPs increase the nonunion rate in forearm fractures.

CONCLUSIONS

Using LPs without compression functionality to treat forearm diaphyseal fractures increases the nonunion rate, particularly in radial shaft fractures. Therefore, we recommend using LCPs or DCPs for forearm diaphyseal fractures to ensure adequate compression at the fracture site during fixation, thereby promoting optimal bone healing rates.

LEVEL OF EVIDENCE

Level III: retrospective comparative therapeutic study.

Outcome Of Dynamic Compression Plate With Dorsal Radial Sliding Graft Technique For Wrist Arthrodesis In Brachial Plexus Injury Patients

BACKGROUND

The incidence of brachial plexus injuries have shown to increase over the years. It is 1- 2% worldwide according to the WHO. In global brachial plexus injuries and lower root injures when the wrist and hand functions are lost, wrist arthrodesis is a viable option. In other cases, when there are some residual hand functions, wrist arthrodesis stabilizes the wrist as well as provides donor muscles tendons to enhance finger functions. Apart from these, wrist arthrodesis increase grip strength and power, and also wrist in extension assume a better shape cosmetically.

PURPOSE

Outcome of dynamic compression plate with dorsal radial sliding graft for wrist arthrodesis in terms of time to union and complications in brachial plexus injury patients.

METHODS

This is a retrospective chart review of patients treated in National Orthopaedic Hospital Bahawalpur, from January 2011 to Sep 2017. All the patients with brachial plexopathies of both genders from age 14 to 60 were included in the study. Data was analysed using MS Excel 2010.

RESULTS

A total of 34 patients were included in the study. Road traffic accidents was the major cause of the injury having 30 (88%) patients whereas birth palsy and gunshots had 2 patients each (6%). Twenty-three patients had no associated fracture while remaining 11 patients had a fracture. There was union in all patients (100 %) and mean time to union was 6.5 weeks (range 6-8) radiologically. Mean follow up was 20.2 months (range 1.5-72).

Mechanics of dynamic compression plate application in fracture fixation

BACKGROUND

Dynamic compression plating is a fundamental type of bone fracture fixation used to generate interfragmentary compression. The goal of this study was to investigate the mechanics of the surgical application of these plates, specifically how plate prebend, screw location, fracture gap, and applied torque influence the resulting compressive pressures.

METHODS

Synthetic bones with transverse fractures were fixed with locking compression plates. One side of the fracture was fixed with locking screws. On the other side of the fracture, a nonlocking screw was inserted eccentrically to induce interfragmentary compression. A pressure mapping sensor within the fracture gap was used to record the resulting pressure distribution. Plate prebends of 0 mm, 1.5 mm, and 3 mm were tested. Three locations of the eccentric screw, four levels of screw torque, and two initial fracture gap conditions also were tested.

FINDINGS

With increasing plate prebend, fracture compression pressures shifted significantly toward the far cortex; however, compression force decreased (P < 0.05). The 1.5 mm prebend plate resulted in the greatest contact area. Increasing screw torque generally resulted in greater fracture compression force. The introduction of a 1 mm fracture gap at the far cortex prior to dynamic compression resulted in little or no fracture compression.

INTERPRETATION

The model showed that increasing plate prebend results in an increasing shift of fracture compression pressures toward the far cortex; however, this is accompanied by decreases in compressive force. Initial fracture gaps at the far cortex can result in little or no compression.

Precontoured dynamic compression plate using patient-specific 3D-printed models in minimally invasive surgical technique for midshaft clavicle fractures

INTRODUCTION

This study introduced a novel approach for the treatment of midshaft clavicle fractures, utilizing patient-specific 3D-printed models for accurate preoperative contouring of dynamic compression plates (DCPs) and an alternative minimally invasive plate osteosynthesis (MIPO) technique with precontoured DCPs through small vertical separated incisions.

PATIENT AND METHODS

Mirror image 3D clavicular models were reproduced from 40 patients with acute displaced midshaft clavicle fractures who underwent MIPO using precontoured DCPs inserted through small, vertical separated incisions. Exclusion criteria included patients with open fractures, pathological fractures, ipsilateral limb injury, skeletal immature patients, and those who had previous clavicle fractures or surgery. Postoperative evaluation was conducted using clinical and radiographic review. The Constant-Murley and American Shoulder and Elbow Surgeons Shoulder Scores were used for clinical evaluations, and the Patient and Observer Scar Assessment Scale was used to assess surgical scars.

RESULTS

The average time to union of all fractures was 12.88 weeks (range, 8-15) without loss of reduction. The patient-specific precontoured DCPs fitted well in all cases, with fracture consolidation and minimal three cortical sides connecting the fracture fragment. No hardware prominence and skin complications occurred, and clinical evaluation showed no existing difference compared with the contralateral sides. The average Constant-Murley and American Shoulder and Elbow Surgeons Shoulder Scores were 96.33 ± 3.66 and 93.26 ± 5.15, respectively. Two patients requested their implant removal, and scar qualities were satisfactory.

CONCLUSIONS

Our study demonstrated that the use of a patient-specific precontoured DCP, in combination with 3D printing technology, provides accurate preoperative planning, effective fracture reduction, and improved postoperative outcomes in displaced midshaft clavicle fractures. The MIPO with a patient-specific precontoured DCP through separated vertical incisions along the Langer's lines appears to be a promising option, regarding appearance, avoiding associated complications, and obviating the need for reoperation. These results suggest that this technique has merit and can be a viable option for the treatment of midshaft clavicle fractures.

Laterally applied single bone plate option for fixation of complete diaphyseal fracture of a third metatarsal bone in a circus work pony

Background

Complete fractures of the third metacarpal/metatarsal bones (Mc/t3) are not common, but can occur in various situations and all types of horses, contributing for approximately one third of all long bone fractures in the horse, mostly related to external trauma or to high energy injuries. To stabilize Mc/t3 fractures in the horse, conservative management with walking casts and/or open reduction and internal fixation techniques are referred in the scientific literature, these last one generally by double platting application to bone surface in 90 degrees. In the present case will be described a Mt3 complete diaphyseal fracture stabilization on an adult pony from a circus by applying only one bone plate. This work pony could return to its previous activity fully recovered 3 months after fracture stabilization.

Case Description

A 7-year-old, male, Shetland pony (103 kg), used for performance work at a circus was admitted to the Veterinary Teaching Hospital of University of Tras-os-Montes and Alto Douro, presenting on lateral recumbency after being struck by a truck. On physical examination, a penetrating wound of small dimension was detected at the medial aspect of the right hindlimb. After radiographic examination, a complete diaphyseal fracture with slight obliquity of the right Mt3 was confirmed. The owner opted for surgical repair thus fracture stabilization was achieved by the placement of just a single 8-hole 4.5 mm broad dynamic compression plate applied to the lateral face of Mt3 in compression function with 7 cortical screws (4.5 mm). Post-operatively a full limb cast was performed and maintained for 4 weeks, while the animal was kept under movement limitation at the hospital facilities for this period of time although the animal stayed until his full recovery 3 months' post-surgery.

Conclusion

A complete recovery was achieved and the animal returned to the previous level of exercise without any significant postoperative complications or degree of lameness. In the authors knowledge, this is the first case report where stabilization of a complete Mt3 diaphyseal fracture was attain using a single compression plate contoured to the lateral face of the bone, instead of double plating, on an adult work pony from a circus subjected to a very demanding and intense physical activity.