Use of bio-resorbable implants for stabilisation of distal radius fractures: the United Kingdom patients' perspective

Three-Dimensional Bioprinting Applications for Bone Tissue Engineering

The skeletal system is a key support structure within the body. Bones have unique abilities to grow and regenerate after injury. Some injuries or degeneration of the tissues cannot rebound and must be repaired by the implantation of foreign objects following injury or disease. This process is invasive and does not always improve the quality of life of the patient. New techniques have arisen that can improve bone replacement or repair. 3D bioprinting employs a printer capable of printing biological materials in multiple directions. 3D bioprinting potentially requires multiple steps and additional support structures, which may include the use of hydrogels for scaffolding. In this review, we discuss normal bone physiology and pathophysiology and how bioprinting can be adapted to further the field of bone tissue engineering.

In Vitro and In Vivo Biosafety Analysis of Resorbable Polyglycolic Acid-Polylactic Acid Block Copolymer Composites for Spinal Fixation

Herein, spinal fixation implants were constructed using degradable polymeric materials such as PGA–PLA block copolymers (poly(glycolic acid-b-lactic acid)). These materials were reinforced by blending with HA-g-PLA (hydroxyapatite-graft-poly lactic acid) and PGA fiber before being tested to confirm its biocompatibility via in vitro (MTT assay) and in vivo animal experiments (i.e., skin sensitization, intradermal intracutaneous reaction, and in vivo degradation tests). Every specimen exhibited suitable biocompatibility and biodegradability for use as resorbable spinal fixation materials.

A Review of Bioresorbable Implantable Medical Devices: Materials, Fabrication, and Implementation

Implantable medical devices (IMDs) are designed to sense specific parameters or stimulate organs and have been actively used for treatment and diagnosis of various diseases. IMDs are used for long-term disease screening or treatments and cannot be considered for short-term applications since patients need to go through a surgery for retrieval of the IMD. Advances in bioresorbable materials has led to the development of transient IMDs that can be resorbed by bodily fluids and disappear after a certain period. These devices are designed to be implanted in the adjacent of the targeted tissue for predetermined times with the aim of measurement of pressure, strain, or temperature, while the bioelectronic devices stimulate certain tissues. They enable opportunities for monitoring and treatment of acute diseases. To realize such transient and miniaturized devices, researchers utilize a variety of materials, novel fabrication methods, and device design strategies. This review discusses potential bioresorbable materials for each component in an IMD followed by programmable degradation and safety standards. Then, common fabrication methods for bioresorbable materials are introduced, along with challenges. The final section provides representative examples of bioresorbable IMDs for various applications with an emphasis on materials, device functionality, and fabrication methods.

CVD-grown monolayer MoS2 in bioabsorbable electronics and biosensors

Transient electronics represents an emerging technology whose defining feature is an ability to dissolve, disintegrate or otherwise physically disappear in a controlled manner. Envisioned applications include resorbable/degradable biomedical implants, hardware-secure memory devices, and zero-impact environmental sensors. 2D materials may have essential roles in these systems due to their unique mechanical, thermal, electrical, and optical properties. Here, we study the bioabsorption of CVD-grown monolayer MoS₂, including long-term cytotoxicity and immunological biocompatibility evaluations in biofluids and tissues of live animal models. The results show that MoS₂ undergoes hydrolysis slowly in aqueous solutions without adverse biological effects. We also present a class of MoS₂-based bioabsorbable and multi-functional sensor for intracranial monitoring of pressure, temperature, strain, and motion in animal models. Such technology offers specific, clinically relevant roles in diagnostic/therapeutic functions during recovery from traumatic brain injury. Our findings support the broader use of 2D materials in transient electronics and qualitatively expand the design options in other areas.

Transient electronics entails the capability of electronic components to dissolve or reabsorb in a controlled manner when used in biomedical implants. Here, the authors perform a systematic study of the processes of hydrolysis, bioabsorption, cytotoxicity and immunological biocompatibility of monolayer MoS₂.

Biocomposite Implants Composed of Poly(Lactide-co-Glycolide)/β-Tricalcium Phosphate: Systematic Review of Imaging, Complication, and Performance Outcomes

PURPOSE

To determine the degradation and performance outcomes of poly(lactide-co-glycolide)/β-tricalcium phosphate (PLGA/β-TCP) implants.

METHODS

A MEDLINE and Embase search for randomized or nonrandomized controlled studies and prospective or retrospective case series that used biocomposite interference screws or suture anchors composed of PLGA/β-TCP was performed. Main outcomes included volume of implant resorption and incidence of osteoconductivity at implant sites, imaging findings, adverse events, and the frequency of reoperations.

RESULTS

A total of 13 studies representing 668 patients with either knee or shoulder implants were included. Median follow-up was 28 months (range: 12-37 months). Biocomposite implants lost 88% of their original volume during follow-up. Osteoconductivity at the implant site was identified in 63% of cases. Adverse events included tunnel widening (3%), effusion (5%), and cyst formation (4%). Synovitis was not reported.

CONCLUSIONS

Biocomposite interference screws or suture anchors composed of PLGA/β-TCP almost fully absorb over 3 years while promoting osteoconductivity with few reported adverse events.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Dimensional evaluation of patient-specific 3D printing using calcium phosphate cement for craniofacial bone reconstruction

The 3D printing process is highlighted nowadays as a possibility to generate individual parts with complex geometries. Moreover, the development of 3D printing hardware, software and parameters permits the manufacture of parts that can be not only used as prototypes, but are also made from materials that are suitable for implantation. In this way, this study investigates the process involved in the production of patient-specific craniofacial implants using calcium phosphate cement, and its dimensional accuracy. The implants were previously generated in a computer-aided design environment based on the patient's tomographic data. The fabrication of the implants was carried out in a commercial 3D powder printing system using alfa-tricalcium phosphate powder and an aqueous solution of Na₂HPO₄ as a binder. The fit of the 3D printed implants was measured by three-dimensional laser scanning and by checking the right adjustment to the patient's anatomical biomodel. The printed parts presented a good degree of fitting and accuracy.

Perspectives of patients about bioabsorbable internal fixation for maxillofacial fractures

PURPOSE

Resorbable/bioabsorbable internal fixation provides effective treatment for maxillofacial fractures and avoids the need for metal hardware removal. We evaluated the initial knowledge, attitudes, subjective demand, and treatment satisfaction of patients concerning bioabsorbable osteofixation for maxillofacial trauma.

MATERIALS AND METHODS

From May 2007 to October 2009, there were 71 patients (63 males and 8 females; mean age: 35 ± 15 years) included in this prospective study. The patients completed preoperative and postoperative (4-6 weeks and 1 year) questionnaires.

RESULTS

After receiving information, 70 patients (99%) preferred resorbable/bioabsorbable bone fixation, usually because they preferred to avoid a second operation to remove metal hardware (67 patients [94%]). The higher cost of resorbable/bioabsorbable bone fixation was believed and justified by 41 patients (58%) and not justified by 30 patients (42%). No adverse events were reported by 27 of 34 patients (79%) at 4-6 weeks and by 14 of 21 patients (67%) at 1 year after surgery. Most patients were very satisfied with the outcome of surgery.

CONCLUSION

Patients who have maxillofacial trauma have a high frequency of preference and high satisfaction with resorbable/bioabsorbable than metal osteofixation. Literature review showed increased activity in research and publication worldwide about resorbable bone fixation, suggesting that there may be increased patient demand for resorbable bone fixation in the future.

Prospective continuous study comparing intrafocal cross-pinning HK2(®) with a locking plate in distal radius fracture fixation

The fixation of distal radius fractures by pinning or locking plates remains controversial. The aim of this prospective continuous study was to compare the results of 28 anterior locking plates with 23 intrafocal cross-pinning HK2(®) systems. The mean age of group I (SVP(®), SBI™ plate) was 61 years. There were 15 extra-articular and 13 articular fractures. The mean age of group II (HK2(®), Arex™) was 63 years, with 13 extra-articular and 10 articular fractures. Twelve clinical variables were measured: pain, wrist strength, supination strength, pronation strength, quick DASH score, range of wrist motion in flexion, extension, pronation, and supination, ulnar variance, radial slope, and radial volar tilt. At 40 weeks follow-up, there was no difference between the two groups for 10 variables; two variables showed differences between the two groups: mean quick DASH score was 10.7 for group I, 19.7 for group II, and mean ulnar variance was -0.95 mm for group I, and 1.16 mm for group II. Six transient complications were noted for group I: five tenosynovitis, and one carpal tunnel syndrome. We noted 12 complications in group II: four superficial infections, two secondary displacements, one pin migration, two CRPS type II, two tendon ruptures and one nerve irritation. Generally, plates provided a more stable fixation associated with less complications while the HK2(®) system was quicker and less costly. The indications for its use need to be refined with a larger series and longer follow-up.

Short-term and long-term effects of orthopedic biodegradable implants

Presently, orthopedic and oral/maxillofacial implants represent a combined $2.8 billion market, a figure expected to experience significant and continued growth. Although traditional permanent implants have been proved clinically efficacious, they are also associated with several drawbacks, including secondary revision and removal surgeries. Non-permanent, biodegradable implants offer a promising alternative for patients, as they provide temporary support and degrade at a rate matching tissue formation, and thus, eliminate the need for secondary surgeries. These implants have been in clinical use for nearly 25 years, competing directly with, or maybe even exceeding, the performance of permanent implants. The initial implantation of biodegradable materials, as with permanent materials, mounts an acute host inflammatory response. Over time, the implant degradation profile and possible degradation product toxicity mediate long-term biodegradable implant-induced inflammation. However, unlike permanent implants, this inflammation is likely to cease once the material disappears. Implant-mediated inflammation is a critical determinant for implant success. Thus, for the development of a proactive biodegradable implant that has the ability to promote optimal bone regeneration and minimal detrimental inflammation, a thorough understanding of short- and long-term inflammatory events is required. Here, we discuss an array of biodegradable orthopedic implants, their associated short- and long- term inflammatory effects, and methods to mediate these inflammatory events.

Patients' preoperative expectations and postoperative satisfaction of dysgnathic patients operated on with resorbable osteosyntheses

BACKGROUND

This study evaluated whether personal expectations and satisfaction throughout orthognathic surgery were fulfilled. In addition, patients were interrogated about their experience of resorbable osteosynthesis.

METHODS

A total of 50 patients were interviewed 3 times each throughout the study by a mixed questionnaire of standard psychologic tests and a tailored itemized questionnaire regarding their expectations regarding resorbable osteofixation and their postoperative satisfaction.

RESULTS

A postoperative increase in self-esteem and approach to life were evident. An examination of Oral Health-Related Quality of Life showed constant quality of life; an examination of Oral Health Impact Profile-Germany) showed no postoperative difficulties in dental hygiene and nutrition. No statistically significant change in any of the tests could be expressly determined. Avoidance of secondary surgery motivated 94% to choose resorbable osteofixations, although a mere 66% had heard of them before; 90% of patients were satisfied with the operation result.

CONCLUSIONS

Orthognathic surgery cannot change preexistent depression or a problematic social background. Mastication and oral health improved, and postoperative happiness and confidence increased. When given the choice between resorbable fixation and titanium osteofixation, patients generally preferred resorbable fixations.

A biomechanical comparison of a biodegradable volar locked plate with two titanium volar locked plates in a distal radius fracture model

BACKGROUND

Volar plating is commonly used in the management of distal radius fractures; bioresorbable plates have attractive features. We compared a bioresorbable plate with a latest generation and an established locked titanium plate.

METHODS

Twenty-four fresh-frozen radii (12 pairs) were assigned to three mean bone mineral density-matched groups of eight radii each. A standardized extraarticular distal radius fracture was created and plated using one implant type per group. Postplating stiffness and displacement were studied in a first axial-loading test (15 cycles at 250 N). Next, biodegradation was simulated by 4 weeks' immersion in phosphate-buffered saline, followed by a second axial test. Finally, the specimens underwent cyclic loading (2,400 cycles at 250 N).

RESULTS

It is clear from the initial test that the LCP plate was significantly stiffer and displaced less than the bioresorbable plate. The outcome of the postimmersion tests is that one bioresorbable plate failed early on after 4 weeks' immersion, and the remaining bioresorbable plates and the T plates did not differ significantly. Cyclic tests conclude that the LCP plate was significantly superior to the other systems. One T plate and four of the bioresorbable plates failed, but none of the LCP plates failed. In the bioresorbable constructs, stability, time to failure, and bone mineral density were significantly correlated.

CONCLUSIONS

The LCP plate was biomechanically superior and may be generally recommended for the volar plating of distal radius fractures. Except one plate failure, the bioresorbable plate was similar to the T plate in the quasi-static tests and should, therefore, be considered for clinical studies, with patient selection confined, initially, only to candidates with good bone stock quality.

Early experience with biodegradable implants in pediatric patients

We retrospectively studied nine children and adolescents with congenital malformations, large reconstruction after tumor excision, fractures and osteotomies of the upper extremity, and hand trauma with bone and soft tissue defects treated by internal synthesis using a biocopolymer of L- and DL-stereoisomers of lactic acid polymers and trimethylenecarbonate. A total of 52 biodegradable implants were placed in bone. At a minimum followup of 7 months (mean, 17 months; range, 7-22 months), wound healing was uncomplicated; local or systemic inflammatory tissue reactions, foreign body reactions, and infections were not observed. Bone healing was complete. Six biodegradable screws broke during insertion because of inadequate drilling and tapping, and three biodegradable screws had to be replaced because of damage to the screw head during assembly with the screwdriver. Biodegradable copolymers of poly-L-lactic-poly-DL-lactic acid and trimethylenecarbonate can be used safely and effectively for reconstruction and fixation of bone in children and adolescents.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Biomechanical evaluation of plate osteosynthesis of distal fibula fractures with biodegradable devices

BACKGROUND

This study compared fixation with a titanium one-third tubular plate and one lag-screw vs. fixation with biodegradable plates with one lag-screw applied with two different plate-screw patterns.

MATERIALS AND METHODS

Ten pairs of fibulas were osteotomied, plated (titanium plate with one lag screw vs. absorbable 2/8 plate-screws crossing vs. 0/8 plate-screws crossing the osteotomy gap). and tested in torsion and bending to obtain stiffness and neutral-zone (NZ) data. Tests were performed using 5 load cycles. No load to failure was performed. Biodegradation was simulated by 6 week immersion in phosphate-buffered saline after which the testing protocol was repeated. The specimens were then loaded with 100 N in bending.

RESULTS

Post-implantation, there were no significant differences, in torsion and bending, regarding the NZ or the stiffness, between the 2/8 biodegradable plate and the titanium plate. The 0/8 pattern performed significantly less well in terms of stiffness and NZ in the initial torsion test, and significantly less well in terms of stiffness in the initial bending test. After 6 weeks' immersion, all biodegradable constructs showed a significantly larger NZ and significantly reduced bending and torsional stiffness. When loaded with 100 N, four of the six 0/8 osteosyntheses failed. There were no significant differences between the 2/8 pattern and the titanium plates.

CONCLUSION

In a model of a Weber-B fracture, the use of a 2/8 biodegradable plate construct initially did not differ statistically to that obtained with a one-third tubular titanium plate. After immersion the 2/8 construct withstood some physiological load.

CLINICAL RELEVANCE

For the fixation of ankle fractures with a biodegradable plate of the type employed in this study, the use of fracture-gap-crossing screws is recommended.

Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices

Heating bioabsorbable plates above T(g) allows for temporary softening to facilitate adaptation to bone. This can, however, transiently alter the mechanical properties, a better understanding of which would provide further insight into the use of these polymers. Two types of unoriented L-lactide/glycolide copolymer wafer specimens (82:18 and 95:5 molar ratios) were heated to 90 degrees C, cooled at various rates, and mechanically tested (three-point bend). Long cooling times ( approximately 8 h) did not change mechanical properties compared to unheated controls, whereas faster cooling rates resulted in increased ductility (50-200% increase in energy to break and peak deformation), however, there was gradual recovery. Under simulated physiological incubation conditions (pH 7.4 buffer, 37 degrees C) partial recovery occurred within 48 h. These results fit well into the theoretical framework of free volume considerations. Following rapid cooling to below T(g), the polymer is not initially at equilibrium, containing excess free volume that contributes to increased molecular mobility and ductile behavior. As equilibrium is approached, free volume decreases and the material behaves as a glassy solid. While there is little clinical consequence as regards internal fixation devices, possible transient changes in permeability and other properties could have implications in drug delivery and other applications.