The state of the art of osseointegration for limb prosthesis

Osseointegration for transfemoral amputees: Influence of femur length and implant sizing on bone-implant contact and alignment

INTRODUCTION

Clinical data on osseointegration (OI) for limb replacement indicates a concerning increase in mechanical complications after five years post-implantation. Since adequate bone-implant contact and proper implant alignment are critical factors for successful osseointegration, it is essential to identify the factors influencing these outcomes. This study aimed to assess the effects of residual femur length and implant sizing on bone-implant contact and implant alignment.

METHODS

Three-dimensional models of eight cadaveric femora were reconstructed from CT scans, and transfemoral amputations were simulated for each femur at three levels: short (ST: 1/3 L), medium (MD: 1/2 L), and long (LG: 2/3 L). Virtual OI surgeries were then performed using computer-aided design (CAD) models, and implant sizes were recorded. Subsequently, the effect of implant sizing was assessed by adjusting the implant size by ±1 mm. Contact length and implant alignment were compared between the groups using repeated measures analysis of variance with Bonferroni correction.

RESULTS

The contact in the ST group (65.2 ± 7.3 %) was significantly less compared to the MD (96.1 ± 4.1 %, p < 0.001) and LG (96.8 ± 3.2 %, p < 0.001) groups. Upsizing increased contact in the ST group by 7.0 ± 2.6 % (p < 0.001), though it did not reach levels comparable to the MD and LG groups (p > 0.05). Additionally, sagittal implant misalignment was larger in the ST group (10.1 ± 2.0°) than in the MD (7.9 ± 1.5°) and LG (3.5 ± 1.6°) groups (p < 0.001), while no difference was observed in coronal implant alignment.

CONCLUSION

These findings highlight the factors influencing mechanical complications of osseointegration implants and provide a basis for refined implant designs and surgical techniques for patients with short residual limbs.

Engineering of Bioresorbable Polymers for Tissue Engineering and Drug Delivery Applications

Herein, the recent advances in the development of resorbable polymeric-based biomaterials, their geometrical forms, resorption mechanisms, and their capabilities in various biomedical applications are critically reviewed. A comprehensive discussion of the engineering approaches for the fabrication of polymeric resorbable scaffolds for tissue engineering, drug delivery, surgical, cardiological, aesthetical, dental and cardiovascular applications, are also explained. Furthermore, to understand the internal structures of resorbable scaffolds, representative studies of their evaluation by medical imaging techniques, e.g., cardiac computer tomography, are succinctly highlighted. This approach provides crucial clinical insights which help to improve the materials' suitable and viable characteristics for them to meet the highly restrictive medical requirements. Finally, the aspects of the legal regulations and the associated challenges in translating research into desirable clinical and marketable materials of polymeric-based formulations, are presented.

Dermatologic Conditions Following Limb Loss

The use of prostheses in individuals with limb loss increases the risk of maceration, friction, and pressure-induced skin injuries due to the vulnerability of the residual limb and the close contact with the socket. Poorly fitting prostheses exacerbate these issues, especially for those with immunosuppression or vascular conditions. Skin pathologies disrupt daily prosthetic limb use and impact the independence of those with limb loss. Preventive measures, including proper prosthesis socket fitting and meticulous skin care, are crucial. This review explores residual limb-site skin pathologies and details current mitigation and management strategies.

Amputation Surgery: Review of New and Emerging Techniques

Major upper and lower extremity amputations are increasingly being performed for peripheral vascular disease, infectious etiologies, trauma, and oncologic purposes. Attention to technique and emerging treatments for the residual peripheral nerve is critical to prosthetic wear and quality of life following these life changing events. Here, we detail advancements in amputation surgery including targeted muscle reinnervation, regenerative peripheral nerve interface, and the use of osseointegrated implants.

The effect of zinc-containing calcium phosphate coating on the osseointegration of transcutaneous implants for limb prosthetics

Introduction Increasing the integration of transcutaneous implants is an important goal for their application in clinical practice.

The purpose of the work was to evaluate the osseointegration of transcutaneous titanium implants with calcium-phosphate coating containing zinc ions.

Materials and methods The studies were performed on 12 male rabbits, who underwent implantation of an original implant into the tibial stump. After implantation, a compression device was installed on the bone, maintaining a load of 3.5 N for 5 weeks. Duration of observation was 26 weeks. The animals were divided into two groups: a control group (n = 6) with an implant without coating and an experimental group (n = 6) with a zinc-substituted calcium-phosphate coated implant.

Results The implant fell out in one case in animals from the control group; no cases of implant loss were noted in the experimental group. It was revealed that the weight concentration of Ca and P in all zones of the bone-implant block of the animals in the experimental group significantly exceeded similar indicators in  the  control group. In the control group, long-term persistence of high levels of C-reactive protein was noted, which was not observed in the experimental group.

Discussion This series of studies has shown that an implant with a zinc-modified calcium-phosphate coating exhibited a more effective integration, in contrast to an uncoated product. The absence of serious adverse reactions to the tested products indicates acceptable tolerability and safety of its use.

Conclusion The implants with a zinc-modified calcium-phosphate coating showed signs of more effective osseointegration compared to the product without additional coating.

Harmonic Vibration Analysis in a Simplified Model for Monitoring Transfemoral Implant Loosening

A simplified axisymmetric model of a transfemoral osseointegration implant was used to investigate the influence of the contact condition at the bone-implant interface on the vibrational response. The experimental setup allowed the degree of implant tightness to be controlled using a circumferential compression device affixed to the bone. Diametrically placed sensors allowed torsional modes to be distinguished from flexural modes. The results showed that the structural resonant frequencies did not shift significantly with tightness levels. The first torsional mode of vibration was found to be particularly sensitive to interface loosening. Harmonics in the vibrational response became prominent when the amplitude of the applied torque increased beyond a critical level. The torque level at which the third harmonic begins to rise correlated with implant criticality, suggesting a potential strategy for early detection of implant loosening based on monitoring the amplitude of the third harmonic of the torsional mode.

New materials and complications of prostheses in humans: situation in Spain

Prostheses or implantable medical devices (IMDs) are parts made of natural or artificial materials intended to replace a body structure and therefore must be well tolerated by living tissues. The types of IMDs currently available and usable are very varied and capable of replacing almost any human organ. A high but imprecise percentage of Spaniards are carriers of one or more IMDs to which they often owe their quality of life or survival. IMDs are constructed with different types of materials that are often combined in the same prosthesis. These materials must combine harmlessness to human tissues with high wear resistance. Their durability depends on many factors both on the host and the type of prosthesis, but the vast majority last for more than 10-15 years or remain in function for the lifetime of the patient. The most frequently implanted IMDs are placed in the heart or great vessels, joints, dental arches or breast and their most frequent complications are classified as non-infectious, particularly loosening or intolerance, and infectious. Complications, when they occur, lead to a significant increase in morbidity, their repair or replacement multiplies the health care cost and, on occasions, can cause the death of the patient. The fight against IMD complications is currently focused on the design of new materials that are more resistant to wear and infection and the use of antimicrobial substances that are released from these materials. Their production requires multidisciplinary technical teams, but also a willingness on the part of industry and health authorities that is not often found in Spain or in most European nations. Scientific production on prostheses and IMD in Spain is estimated to be less than 2% of the world total, and probably below what corresponds to our level of socio-economic development. The future of IMDs involves, among other factors, examining the potential role of Artificial Intelligence in their design, knowledge of tissue regeneration, greater efficiency in preventing infections and taking alternative treatments beyond antimicrobials, such as phage therapy. For these and other reasons, the Ramón Areces Foundation convened a series of experts in different fields related to prostheses and IMDs who answered and discussed a series of questions previously formulated by the Scientific Council. The following lines are the written testimony of these questions and the answers to them.

Comparison In Vitro Study on the Interface between Skin and Bone Cell Cultures and Microporous Titanium Samples Manufactured with 3D Printing Technology Versus Sintered Samples

Percutaneous implants osseointegrated into the residuum of a person with limb amputation need to provide mechanical stability and protection against infections. Although significant progress has been made in the biointegration of percutaneous implants, the problem of forming a reliable natural barrier at the level of the surface of the implant and the skin and bone tissues remains unresolved. The use of a microporous implant structure incorporated into the Skin and Bone Integrated Pylon (SBIP) should address the issue by allowing soft and bone tissues to grow directly into the implant structure itself, which, in turn, should form a reliable barrier to infections and support strong osseointegration. To evaluate biological interactions between dermal fibroblasts and MC3T3-E1 osteoblasts in vitro, small titanium discs (with varying pore sizes and volume fractions to achieve deep porosity) were fabricated via 3D printing and sintering. The cell viability MTT assay demonstrated low cytotoxicity for cells co-cultured in the pores of the 3D-printed and sintered Ti samples during the 14-day follow-up period. A subsequent Quantitative Real-Time Polymerase Chain Reaction (RT-PCR) analysis of the relative gene expression of biomarkers that are associated with cell adhesion (α2, α5, αV, and β1 integrins) and extracellular matrix components (fibronectin, vitronectin, type I collagen) demonstrated that micropore sizes ranging from 200 to 500 µm of the 3D printed and sintered Ti discs were favorable for dermal fibroblast adhesion. For example, for representative 3D-printed Ti sample S6 at 72 h the values were 4.71 ± 0.08 (α2 integrin), 4.96 ± 0.08 (α5 integrin), 4.71 ± 0.08 (αV integrin), and 1.87 ± 0.12 (β1 integrin). In contrast, Ti discs with pore sizes ranging from 400 to 800 µm demonstrated the best results (in terms of marker expression related to osteogenic differentiation, including osteopontin, osteonectin, osteocalcin, TGF-β1, and SMAD4) for MC3T3-E1 cells. For example, for the representative 3D sample S4 on day 14, the marker levels were 11.19 ± 0.77 (osteopontin), 7.15 ± 0.29 (osteonectin), and 6.08 ± 0.12 (osteocalcin), while for sintered samples the levels of markers constituted 5.85 ± 0.4 (osteopontin), 4.45 ± 0.36 (osteonectin), and 4.46 ± 0.3 (osteocalcin). In conclusion, the data obtained show the high biointegrative properties of porous titanium structures, while the ability to implement several pore options in one structure using 3D printing makes it possible to create personalized implants for the best one-time integration with both skin and bone tissues.

Advantages of customization of osseointegrated implants in transfemoral amputees: a comparative analysis of surgical planning

BACKGROUND

Commercially available osseointegrated devices for transfemoral amputees are limited in size and thus fail to meet the significant anatomical variability in the femoral medullary canal. This study aimed to develop a customized osseointegrated stem to better accommodate a variety of femoral anatomies in transfemoral amputees than off-the-shelf stems. Customization is expected to enhance cortical bone preservation and increase the stem-bone contact area, which are critical for the long-term stability and success of implants.

METHODS

A customized stem (OsteoCustom) was designed based on the statistical shape variability of the medullary canal. The implantability of the OsteoCustom stem was tested via 70 computed tomography (CT) images of human femurs and compared to that of a commercial device (OFI-C) for two different resection levels. The evaluations included the volume of cortical bone removed and the percentage of stem-bone contact area for both resection levels. Statistical significance was analyzed using paired and unpaired t tests.

RESULTS

The OsteoCustom stem could be virtually implanted in all 70 femurs, while the OFI-C was unsuitable in 19 cases due to insufficient cortical thickness after implantation, further emphasizing its adaptability to varying anatomical conditions. The OsteoCustom stem preserved a greater volume of cortical bone than did the OFI-C. In fact, 42% less bone was removed at the proximal resection level (3.15 cm³ vs. 5.42 cm³, p ≤ 0.0001), and 33% less at the distal resection level (2.25 cm³ vs. 3.39 cm³, p = 0.003). The stem-bone contact area was also greater for the OsteoCustom stem, particularly at the distal resection level, showing a 20% increase in contact area (52.3% vs. 32.2%, p = 0.002) compared to that of the OFI-C.

CONCLUSIONS

The OsteoCustom stem performed better than the commercial stem by preserving more cortical bone and achieving a greater stem-bone contact area, especially at distal resection levels where the shape of the medullary canal exhibits more inter-subject variability. Optimal fit in the distal region is of paramount importance for ensuring the stability of osseointegrated implants. This study highlights the potential benefits of customized osseointegrated stems in accommodating a broader range of femoral anatomies, with enhanced fit in the medullary canal.

Emerging Value of Osseointegration for Intuitive Prosthetic Control after Transhumeral Amputations: A Systematic Review

Background

Upper extremity limb loss profoundly impacts a patient's quality of life and well-being and carries a significant societal cost. Although osseointegration allows the attachment of the prosthesis directly to the bone, it is a relatively recent development as an alternative to conventional socket prostheses. The objective of this review was to identify reports on osseointegrated prosthetic embodiment for transhumeral amputations and assess the implant systems used, postoperative outcomes, and complications.

Methods

A systematic review following PRISMA and AMSTAR guidelines assessed functional outcomes, implant longevity and retention, activities of daily living, and complications associated with osseointegrated prostheses in transhumeral amputees.

Results

The literature search yielded 794 articles, with eight of these articles (retrospective analyses and case series) meeting the inclusion criteria. Myoelectric systems equipped with Osseointegrated Prostheses for the Rehabilitation of Amputees implants have been commonly used as transhumeral osseointegration systems. The transhumeral osseointegrated prostheses offered considerable improvements in functional outcomes, with participants demonstrating enhanced range of motion and improved performance of activities compared with traditional socket-based prostheses. One study demonstrated the advantage of an osseointegrated implant as a bidirectional gateway for signal transmission, enabling intuitive control of a bionic hand.

Conclusions

Osseointegrated prostheses hold the potential to significantly improve the quality of life for individuals with transhumeral amputations. Continued research and clinical expansion are expected to lead to the realization of enhanced efficacy and safety in this technique, accompanied by cost reductions over time as a result of improved efficiencies and advancements in device design.

Soft and Hard Tissue Integration around Percutaneous Bone-Anchored Titanium Prostheses: Toward Achieving Holistic Biointegration

A holistic biointegration of percutaneous bone-anchored metallic prostheses with both hard and soft tissues dictates their longevity in the human body. While titanium (Ti) has nearly solved osseointegration, soft tissue integration of percutaneous metallic prostheses is a perennial problem. Unlike the firm soft tissue sealing in biological percutaneous structures (fingernails and teeth), foreign body response of the skin to titanium (Ti) leads to inflammation, epidermal downgrowth and inferior peri-implant soft tissue sealing. This review discusses various implant surface treatments/texturing and coatings for osseointegration, soft tissue integration, and against bacterial attachment. While surface microroughness by SLA (sandblasting with large grit and acid etched) and porous calcium phosphate (CaP) coatings improve Ti osseointegration, smooth and textured titania nanopores, nanotubes, microgrooves, and biomolecular coatings encourage soft tissue attachment. However, the inferior peri-implant soft tissue sealing compared to natural teeth can lead to peri-implantitis. Toward this end, the application of smart multifunctional bioadhesives with strong adhesion to soft tissues, mechanical resilience, durability, antibacterial, and immunomodulatory properties for soft tissue attachment to metallic prostheses is proposed.

A scoring system to evaluate stability of percutaneous osseointegrated implants for transfemoral amputation with validation in the ITAP clinical trial

Percutaneous osseointegrated implants for individuals with lower limb amputation can increase mobility, reduce socket related pain, and improve quality of life. It would be useful to have an evaluation method to assess the interface between bone and implant. We assessed outpatient radiographs from the Intraosseous Transcutaneous Amputation Prosthesis clinical trial using an interface scoring system which summed and weighted equally measures of implant collar cortical ongrowth and radiolucency along the implant stem/bone interface. Radiographs from 12 participants with unilateral transfemoral amputations (10 males, 2 females, mean age = 43.2, SD = 7.4 years) in the clinical trial from cohort I (implanted in 2008/09) or cohort II (implanted in 2013/14) were collated (mean image span = 7.2, SD = 2.4 years), scale normalised, zoned, and measured in a repeatable way. Interface scores were calculated and then compared to clinical outcomes. Explanted participants received the lowest interface scores. A higher ratio of stem to residuum and shorter residuum's produced better interface scores and there was an association (weak correlation) between participants with thin cortices and the lowest interface scores. A tapered, cemented, non curved stem may provide advantageous fixation while stem alignment did not appear critical. In summary, the interface score successfully demonstrated a non-invasive evaluation of percutaneous osseointegrated implants interfaces when applied to the Intraosseous Transcutaneous Amputation Prosthesis clinical trial. The clinical significance of this work is to identify events leading to aseptic or septic implant removal and contribute to clinical guidelines for monitoring rehabilitation, design and surgical fixation choices.

Association between blood markers and the progression of osseointegration in percutaneous prostheses patients-A pilot study

Patients implanted with osseointegrated (OI) prosthetic systems have reported vastly improved upper and lower extremity prosthetic function compared with their previous experience with socket-suspension systems. However, OI systems have been associated with superficial and deep-bone infections and implant loosening due, in part, to a failure of the osseointegration process. Although monitoring the osseointegration using circulating biomarkers has clinical relevance for understanding the progression of osseointegration with these devices, it has yet to be established. Ten patients were enrolled in this study. Blood samples were collected at pre-selected times, starting before implantation surgery, and continuing to 12 months after the second surgery. Bone formation markers, bone resorption markers, and circulating amino acids were measured from blood samples. A linear mixed model was generated for each marker, incorporating patient ID and age with the normalized marker value as the response variable. Post hoc comparisons were made between 1 week before Stage 1 Surgery and all subsequent time points for each marker, followed by multiple testing corrections. Serial radiographic imaging of the residual limb containing the implant was obtained during follow-up, and the cortical index (CI) was calculated for the bone at the porous region of the device. Two markers of bone formation, specifically bone-specific alkaline phosphatase (Bone-ALP) and amino-terminal propeptide of type I procollagen (PINP), exhibited significant increases when compared with the baseline levels of unloaded residual bone prior to the initial surgery, and they subsequently returned to their baseline levels by the 12-month mark. Patients who experienced clinically robust osseointegration experienced increased cortical bone thickness at the porous coated region of the device. A medium correlation was observed between Bone-ALP and the porous CI values up to PoS2-M1 (p = .056), while no correlation was observed for PINP. An increase in bone formation markers and the lack of change observed in bone resorption markers likely reflect increased cortical bone formation induced by the end-loading design of the Utah OI device used in this study. A more extensive study is required to validate the correlation observed between Bone-ALP and porous CI values.

An antimicrobial blue light device to manage infection at the skin-implant interface of percutaneous osseointegrated implants

Antimicrobial blue light (aBL) is an attractive option for managing biofilm burden at the skin-implant interface of percutaneous osseointegrated (OI) implants. However, marketed aBL devices have both structural and optical limitations that prevent them from being used in an OI implant environment. They must be handheld, preventing even irradiation of the entire skin-implant interface, and the devices do not offer sufficient optical power outputs required to kill biofilms. We present the developmental process of a unique aBL device that overcomes these limitations. Four prototypes are detailed, each being a progressive improvement from the previous iteration as we move from proof-of-concept to in vivo application. Design features focused on a cooling system, LED orientation, modularity, and "sheep-proofing". The final prototype was tested in an in vivo OI implant sheep model, demonstrating that it was structurally and optically adequate to address biofilm burdens at the skin-implant of percutaneous OI implants. The device made it possible to test aBL in the unique OI implant environment and compare its efficacy to clinical antibiotics-data which had not before been achievable. It has provided insight into whether or not continued pursual of light therapy research for OI implants, and other percutaneous devices, is worthwhile. However, the device has drawbacks concerning the cooling system, complexity, and size if it is to be translated to human clinical trials. Overall, we successfully developed a device to test aBL therapy for patients with OI implants and helped progress understanding in the field of infection management strategies.

Soft robotics in wearable and implantable medical applications: Translational challenges and future outlooks

This work explores the recent research conducted towards the development of novel classes of devices in wearable and implantable medical applications allowed by the introduction of the soft robotics approach. In the medical field, the need for materials with mechanical properties similar to biological tissues is one of the first considerations that arises to improve comfort and safety in the physical interaction with the human body. Thus, soft robotic devices are expected to be able of accomplishing tasks no traditional rigid systems can do. In this paper, we describe future perspectives and possible routes to address scientific and clinical issues still hampering the accomplishment of ideal solutions in clinical practice.

Optimising soft tissue in-growth in vivo in additive layer manufactured osseointegrated transcutaneous implants

Osseointegrated transcutaneous implants could provide an alternative and improved means of attaching artificial limbs for amputees, however epithelial down growth, inflammation, and infections are common failure modalities associated with their use. To overcome these problems, a tight seal associated with the epidermal and dermal adhesion to the implant is crucial. This could be achieved with specific biomaterials (that mimic the surrounding tissue), or a tissue-specific design to enhance the proliferation and attachment of dermal fibroblasts and keratinocytes. The intraosseous transcutaneous amputation prosthesis is a new device with a pylon and a flange, which is specifically designed for optimising soft tissue attachment. Previously the flange has been fabricated using traditional machining techniques, however, the advent of additive layer manufacturing (ALM) has enabled 3-dimensional porous flanges with specific pore sizes to be used to optimise soft tissue integration and reduce failure of osseointegrated transcutaneous implants. The study aimed to investigate the effect of ALM-manufactured porous flanges on soft tissue ingrowth and attachment in an in vivo ovine model that replicates an osseointegrated percutaneous implant. At 12 and 24 weeks, epithelial downgrowth, dermal attachment and revascularisation into ALM-manufactured flanges with three different pore sizes were compared with machined controls where the pores were made using conventional drilling. The pore sizes of the ALM flanges were 700, 1000 and 1250 μm. We hypothesised that ALM porous flanges would reduce downgrowth, improve soft tissue integration and revascularisation compared with machined controls. The results supported our hypothesis with significantly greater soft tissue integration and revascularisation in ALM porous flanges compared with machined controls.

Plasma polymerized bio-interface directs fibronectin adsorption and functionalization to enhance "epithelial barrier structure" formation via FN-ITG β1-FAK-mTOR signaling cascade

BACKGROUND

Transepithelial medical devices are increasing utilized in clinical practices. However, the damage of continuous natural epithelial barrier has become a major risk factor for the failure of epithelium-penetrating implants. How to increase the "epithelial barrier structures" (focal adhesions, hemidesmosomes, etc.) becomes one key research aim in overcoming this difficulty. Directly targeting the in situ "epithelial barrier structures" related proteins (such as fibronectin) absorption and functionalization can be a promising way to enhance interface-epithelial integration.

METHODS

Herein, we fabricated three plasma polymerized bio-interfaces possessing controllable surface chemistry. Their capacity to adsorb and functionalize fibronectin (FN) from serum protein was compared by Liquid Chromatography-Tandem Mass Spectrometry. The underlying mechanisms were revealed by molecular dynamics simulation. The response of gingival epithelial cells regarding the formation of epithelial barrier structures was tested.

RESULTS

Plasma polymerized surfaces successfully directed distinguished protein adsorption profiles from serum protein pool, in which plasma polymerized allylamine (ppAA) surface favored adsorbing adhesion related proteins and could promote FN absorption and functionalization via electrostatic interactions and hydrogen bonds, thus subsequently activating the ITG β1-FAK-mTOR signaling and promoting gingival epithelial cells adhesion.

CONCLUSION

This study offers an effective perspective to overcome the current dilemma of the inferior interface-epithelial integration by in situ protein absorption and functionalization, which may advance the development of functional transepithelial biointerfaces. Tuning the surface chemistry by plasma polymerization can control the adsorption of fibronectin and functionalize it by exposing functional protein domains. The functionalized fibronectin can bind to human gingival epithelial cell membrane integrins to activate epithelial barrier structure related signaling pathway, which eventually enhances the formation of epithelial barrier structure.

Osseointegration for Lower-Extremity Amputees: Operative Considerations from the Plastic Surgeon's Perspective

➢

Osseointegration for lower-extremity amputees, while increasing in frequency, remains in its relative infancy compared with traditional socket-based prostheses.

➢

Ideal candidates for osseointegration have documented failure of a traditional prosthesis and should be skeletally mature, have adequate bone stock, demonstrate an ability to adhere to a longitudinal rehabilitation protocol, and be in an otherwise good state of health.

➢

Lowering the reoperation rate for soft-tissue complications depends heavily on surgical technique and on the implant device itself; the current gold standard involves a smooth implant surface for dermal contact as well as maximal skin resection to prevent skin breakdown against the prosthesis. This may include the need for thighplasty to optimize skin reduction.

➢

Interdisciplinary peripheral nerve management, such as targeted muscle reinnervation, performed in tandem with a plastic surgery team can treat existing and prevent future symptomatic neuromas, ultimately improving pain outcomes.

Determining the Antibiofilm Efficacy of Oregano Gel in an Ex Vivo Model of Percutaneous Osseointegrated Implants

Biofilm contamination is common in patients with percutaneous osseointegrated (OI) implants, leading to frequent infections, irritation, and discomfort. Reported infection rates soar up to 65% as the recalcitrant nature of biofilms complicates treatment. There is persistent need for therapies to manage biofilm burden. In response, we formulated and tested oregano essential oil in a topical gel as a potential biofilm management therapy. We developed an ex vivo system based on an established ovine OI implant model with Staphylococcus aureus ATCC 6538 biofilms as initial inocula. Gel was administered to the samples across a period of five days. Samples were quantified and colony forming unit (CFU) counts were compared against a positive control (initial bacterial inocula without treatment). Significant biofilm reduction was observed in samples treated with oregano gel compared to controls, demonstrating the potential of an oregano oil-based gel as a biofilm management therapy at the skin-implant interface of percutaneous OI implants.

Fifty years of bone tumors

There have been enormous advances in the treatment of bone tumors over the past half-century. The most notable of these has been the transition from amputation as the standard of care to limb salvage surgery. This transition is the result of advances in imaging techniques, accurate diagnosis, systemic therapies (including chemotherapy), and prosthetic design for the reconstruction of musculoskeletal defects. Advances have also been made in the management of benign and metastatic bone tumors.

Implantable biosensors for musculoskeletal health

PURPOSE

A healthy musculoskeletal system requires complex functional integration of bone, muscle, cartilage, and connective tissues responsible for bodily support, motion, and the protection of vital organs. Conditions or injuries to musculoskeeltal tissues can devastate an individual's quality of life. Some conditions that are particularly disabling include severe bone and muscle injuries to the extremities and amputations resulting from unmanageable musculoskeletal conditions or injuries. Monitoring and managing musculoskeletal health is intricate because of the complex mechanobiology of these interconnected tissues.

METHODS

For this article, we reviewed literature on implantable biosensors related to clinical data of the musculoskeletal system, therapeutics for complex bone injuries, and osseointegrated prosthetics as example applications.

RESULTS

As a result, a brief summary of biosensors technologies is provided along with review of noteworthy biosensors and future developments needed to fully realize the translational benefit of biosensors for musculoskeletal health.

CONCLUSIONS

Novel implantable biosensors capable of tracking biophysical parameters in vivo are highly relevant to musculoskeletal health because of their ability to collect clinical data relevant to medical decisions, complex trauma treatment, and the performance of osseointegrated prostheses.

Extramedullary Osseointegration-A Novel Design of Percutaneous Osseointegration Prosthesis for Amputees

The percutaneous osseointegrated (OI) prostheses have greatly improved the overall quality of life for amputees. However, the long-term maintenance of the OI prostheses is still challenging. A major problem is bone resorption around the bone-implant-skin interface, which might cause implant loosening or osteomyelitis. Another problem is the breakage of connecting components between the intramedullary implant and external prosthesis due to excessive stress. We designed a novel osseointegration implant by changing the bone-implant contact from the inner cortex to the outer surface of cortical bone. In the current study, we compared the extramedullary cap-shaped implants with the intramedullary screw-type implants in rabbits. Osteointegration was confirmed at the interface of bone to implant contact (BIC) in both implant types. The external implant induced intramedullary bone regeneration in the medullary canal and increased the cortical bone density at the end of the stump. This study provides a new perspective on the design of osseointegration implants which might prevent the currently reported complications of the intramedullary OI systems.

Trends and Opportunities in Health Economic Evaluations of Prosthetic Care Innovations

Overcoming obstacles to prosthetic fittings requires frequent tryouts of sockets and components. Repetitions of interventions are upsetting for users and place substantial economic burden on healthcare systems. Encouraging prosthetic care innovations capable of alleviating clinical and financial shortcomings of socket-based solutions is essential. Nonetheless, evidence of socio-economic benefits of an innovation are required to facilitate access to markets. Unfortunately, complex decisions must be made when allocating resources toward the most relevant health economic evaluation (HEE) at a given stage of development of an innovation. This paper first, aimed to show the importance and challenges of HEEs of intervention facilitating prosthetic fittings. Next, the main trends in HEEs at various phases of product development and clinical acceptance of prosthetic care innovations were outlined. Then, opportunities for a basic framework of a preliminary cost-utility analysis (CUA) during the mid-stage of development of prosthetic care innovations were highlighted. To do this, fundamental and applied health economic literature and prosthetic-specific publications were reviewed to extract and analyse the trends in HEEs of new medical and prosthetic technologies, respectively. The findings show there is consensus around the weaknesses of full CUAs (e.g., lack of timeliness, resource-intensive) and strengths of preliminary CUAs (e.g., identify evidence gaps, educate design of full CUA, fast-track approval). However, several obstacles must be overcome before preliminary CUA of prosthetic care innovations will be routinely carried out. Disparities of methods and constructs of usual preliminary CUA are barriers that could be alleviated by a more standardized framework. The paper concludes by identifying that there are opportunities for the development of a basic framework of preliminary CUA of prosthetic care innovations. Ultimately, the collaborative design of a framework could simplify selection of the methods, standardise outcomes, ease comparisons between innovations and streamline pathways for adoption. This might facilitate access to economical solutions that could improve the life of individuals suffering from limb loss.

Health Service Delivery and Economic Evaluation of Limb Lower Bone-Anchored Prostheses: A Summary of the Queensland Artificial Limb Service's Experience

The emergence of skeletal prosthetic attachments leaves governmental organizations facing the challenge of implementing equitable policies that support the provision of bone-anchored prostheses (BAPs). In 2013, the Queensland Artificial Limb Service (QALS) started a five-year research project focusing on health service delivery and economic evaluation of BAPs. This paper reflects on the QALS experience, particularly the lessons learned. QALS' jurisdiction and drivers are presented first, followed by the impact of outcomes, barriers, and facilitators, as well as future developments of this work. The 21 publications produced during this project (e.g., reimbursement policy, role of prosthetists, continuous improvement procedure, quality of life, preliminary cost-utilities) were summarized. Literature on past, current, and upcoming developments of BAP was reviewed to discuss the practical implications of this work. A primary outcome of this project was a policy developed by QALS supporting up to 22 h of labor for the provision of BAP care. The indicative incremental cost-utility ratio for transfemoral and transtibial BAPs was approximately AUD$17,000 and AUD$12,000, respectively, per quality-adjusted life-year compared to socket prostheses. This project was challenged by 17 barriers (e.g., limited resources, inconsistency of care pathways, design of preliminary cost-utility analyses) but eased by 18 facilitators (e.g., action research plan, customized database, use of free repositories). In conclusion, we concluded that lower limb BAP might be an acceptable alternative to socket prostheses from an Australian government prosthetic care perspective. Hopefully, this work will inform promoters of prosthetic innovations committed to making bionic solutions widely accessible to a growing population of individuals suffering from limb loss worldwide.

A trilogy antimicrobial strategy for multiple infections of orthopedic implants throughout their life cycle

Bacteria-associated infection represents one of the major threats for orthopedic implants failure during their life cycles. However, ordinary antimicrobial treatments usually failed to combat multiple waves of infections during arthroplasty and prosthesis revisions etc. As these incidents could easily introduce new microbial pathogens in/onto the implants. Herein, we demonstrate that an antimicrobial trilogy strategy incorporating a sophisticated multilayered coating system leveraging multiple ion exchange mechanisms and fine nanotopography tuning, could effectively eradicate bacterial infection at various stages of implantation. Early stage bacteriostatic effect was realized via nano-topological structure of top mineral coating. Antibacterial effect at intermediate stage was mediated by sustained release of zinc ions from doped CaP coating. Strong antibacterial potency was validated at 4 weeks post implantation via an implanted model in vivo. Finally, the underlying zinc titanate fiber network enabled a long-term contact and release effect of residual zinc, which maintained a strong antibacterial ability against both Staphylococcus aureus and Escherichia coli even after the removal of top layer coating. Moreover, sustained release of Sr2+ and Zn2+ during CaP coating degradation substantially promoted implant osseointegration even under an infectious environment by showing more peri-implant new bone formation and substantially improved bone-implant bonding strength.

Successful salvage via re-osseointegration of a loosened implant in a patient with transtibial amputation

CASE DESCRIPTION

Osseointegration is a relatively new technique for prosthetic limb attachment that offers various improvements for patients with amputation and facilitates joint preservation. We present a case of implant loosening during rehabilitation in a patient with transtibial amputation that was successfully managed through a combination of measures, aiming to promote re-osseointegration of the implant.

OBJECTIVES

Not much is known about structured management of adverse events after osseointegration. Septic or aseptic loosening is currently regarded as implant failure, prompting removal and possible re-implantation at a later stage. The objective of this case report was to evaluate the feasibility of salvaging a loosened implant.

STUDY DESIGN

Case report.

TREATMENT

A novel treatment approach was employed to enable renewed osseointegration of the implant. First, the bone-implant interface was disrupted and renewed through axial rotation and distal repositioning of the implant. Afterwards, extracorporal shockwave therapy and antibiotic treatment were administered. Prosthetic rehabilitation was then started anew. Regular follow-up x-rays and clinical evaluations were conducted, including standardized outcome tests.

OUTCOMES

These combined measures led to a successful re-osseointegration of the implant. In a 21-month follow-up, the patient regained a stable and secure gait pattern, using his prosthesis every day for 15 hours and scoring above average on standardized outcome measures.

CONCLUSION

This represents the first report of implant salvage after failed primary osseointegration. As the associated risks of this novel treatment are very low, investigations are warranted to evaluate this approach on a larger scale.

Percutaneous cementoplasty of periprosthetic loosening: can interventional radiologists offer an alternative to revision surgery?

OBJECTIVE

To evaluate feasibility and validate both safety and efficiency of radiological percutaneous periprosthetic bone cementoplasty (RPPBC) performed under local anesthesia as an alternative minimally invasive treatment of aseptic implant loosening.

METHODS

In this case series, seven patients (mean age 81 years, range 73 to 89 years, 2 men and 5 women) were enrolled between February 2011 and January 2020 with confirmed aseptic loosening of orthopedic implants. One patient presented with tibial component loosening of an unicompartmental knee arthroplasty, one with glenoid component loosening from a reverse shoulder arthroplasty, one femoral gamma nail, and four presented with pedicle screw loosening after staged posterior lumbar interbody fusion. All patients underwent clinical, biochemical, and imaging assessments to confirm the diagnosis of aseptic loosening. All benefited from RPPBC under dual CT and fluoroscopic guidance. All procedures were performed under local anesthesia by an experienced radiologist. Preprocedural, immediate and 6-month post-cementoplasty pain levels on a visual analogue scale (VAS), and functional outcomes were evaluated. Immediate and 6-month postprocedural CTs were performed to evaluate the treated region.

RESULTS

All RPPBC were well tolerated by patients throughout the procedure. None of the patients suffered from local or systemic infection post-RPPBC, or periprosthetic fractures. No recurrent implant loosening was observed. Six patients were pain free at 6 months. All patients expressed functional improvements during validated outcome score evaluations.

CONCLUSION

RPPBC appears to be an efficient and reliable treatment strategy for aseptic loosening of orthopedic implants in elderly patients deemed unfit for revision surgery.

KEY POINTS

• Radiological percutaneous periprosthetic bone cementoplasty offers immediate and long-lasting pain relief in elderly frail patients, or those deemed unfit for revision surgery despite presenting with symptomatic aseptic loosening of orthopedic implants. • Radiological percutaneous periprosthetic bone cementoplasty brings quick and long-lasting improvements in clinical functional outcomes and offer effective pain reduction, thereby improving the overall quality of life. • Radiological percutaneous periprosthetic bone cementoplasty is a safe, quick, reliable, and well-tolerated minimally invasive procedure which can be easily performed under simple locoregional anesthesia and requires short-term hospital stay.