Bilateral Total Knee Arthroplasties in a Patient with Bilateral Below-Knee Amputations and Osseointegration Limb Replacements: A Case Report.

CASE: A 38-year-old man with congenital pain insensitivity underwent bilateral below-knee amputations. After his subsequent bilateral osseointegration (OI) limb replacements, he rapidly developed severe bilateral knee arthritis and varus deformity. In lieu of performing bilateral above-knee amputations, he underwent bilateral staged total knee arthroplasties (TKA) with excellent clinical and radiographic evaluation at 1-year follow-up. CONCLUSION: To address both the limited bone stock and OI implant stem location, TKA after OI limb replacement in congenital pain insensitivity patients can be successfully achieved with a nonkeeled cementless tibial component and augmentation with a tibial cone.

Ranking Decision-Making Criteria for Early Adoption of Innovative Surgical Technologies.

Importance: There is no decision-making framework in the early-adoption stage of novel surgical technologies, putting the quality of health care and resource allocation of the health care system at risk. Objective: To investigate relevant weighted criteria that decision-makers may use to make an informed decision for the early adoption of innovative surgical technologies. Design, Setting, and Participants: This multi-institutional decision analytical modeling study used a mixed-methods multicriteria decision analysis (MCDA) and had 2 phases. First, a panel of 12 experts validated decision criteria in the literature and identified additional criteria. Second, 33 Canadian experts prioritized the main criteria (domains) using the composition pairwise-comparison weight-elicitation method (analytical hierarchy process model) and ranked their subcriteria using the direct-ranking elicitation method (Likert scale). Data were analyzed, and response consistency was estimated using the consistency ratio. Analysis of variance was used to assess for significant differences between expert responses. The MCDA was conducted at McGill University between 2021 and 2023. Data were collected nationally by inviting experts in Canada. Main Outcome and Measure: Criteria domain weights and subcriteria rankings. Priority vectors, which are priority scores analyzed and prioritized from expert responses, were used to rank criteria domains and subcriteria for decision-making on adopting new innovative surgical technologies. Results: A total of 45 experts (33 male [73.3%] and 12 female [26.7%]) were invited with different levels of education (22 experts with MD or equivalent, 13 experts with master's degree, and 12 experts with PhD degree) and years of experience (4 experts with <10, 12 experts with 11-20, 18 experts with 21-30, and 11 experts with >30 years). Surgeon experts (23 individuals) were from all surgical disciplines, and nonsurgeon experts (22 individuals) were administrative officers in surgical device procurement, health technology assessment experts, and hospital directors. A total of 7 domains and 44 subcriteria were identified. The MCDA model found that clinical outcomes had the highest priority vector, at 0.429, followed by patients and public relevance (0.135). Hospital-specific criteria (priority vector, 0.099), technology-specific criteria (priority vector, 0.092), and physician-specific criteria (priority vector, 0.087) were the next most highly ranked. The lowest priority vectors were for economic criteria, at 0.083, and finally policies and procedures, at 0.075. There was consensus in the responses (consistency ratio = 0.006), and there were no statistically significant differences between expert responses. Conclusions and relevance: This study weighted priority criteria domains in importance and established ranked subcriteria for decision-making of early adoption of surgical technologies. Putting these criteria into a framework may help surgeons and decision-makers make informed decisions for the early adoption of new surgical technologies.

Titanium-Dioxide-Nanoparticle-Embedded Polyelectrolyte Multilayer as an Osteoconductive and Antimicrobial Surface Coating.

Bioactive surface coatings have retained the attention of researchers and physicians due to their versatility and range of applications in orthopedics, particularly in infection prevention. Antibacterial metal nanoparticles (mNPs) are a promising therapeutic, with vast application opportunities on orthopedic implants. The current research aimed to construct a polyelectrolyte multilayer on a highly porous titanium implant using alternating thin film coatings of chitosan and alginate via the layer-by-layer (LbL) self-assembly technique, along with the incorporation of silver nanoparticles (AgNPs) or titanium dioxide nanoparticles (TiO2NPs), for antibacterial and osteoconductive activity. These mNPs were characterized for their physicochemical properties using quartz crystal microgravimetry with a dissipation system, nanoparticle tracking analysis, scanning electron microscopy, and atomic force microscopy. Their cytotoxicity and osteogenic differentiation capabilities were assessed using AlamarBlue and alkaline phosphatase (ALP) activity assays, respectively. The antibiofilm efficacy of the mNPs was tested against Staphylococcus aureus. The LbL polyelectrolyte coating was successfully applied to the porous titanium substrate. A dose-dependent relationship between nanoparticle concentration and ALP as well as antibacterial effects was observed. TiO2NP samples were also less cytotoxic than their AgNP counterparts, although similarly antimicrobial. Together, these data serve as a proof-of-concept for a novel coating approach for orthopedic implants with antimicrobial and osteoconductive properties.

Ceramic-on-Ceramic Total Hip Arthroplasty: I Can Hear You.

Background: Squeaking is a known complication of ceramic-on-ceramic (CoC) total hip arthroplasty (THA), yet there is a lack of studies specifically quantifying its loudness. The aims of this study were: (1) to determine the incidence of squeaking in CoC THAs at long-term follow-up; (2) to identify risk factors; and (3) to quantify the loudness of the squeaking. Methods: A specifically designed prospective questionnaire was used to determine the prevalence, characteristics, and loudness of squeaking in 130 (110 patients) primary THAs with fourth-generation CoC bearings at a mean follow-up of 10.5 years. The loudness of the squeaking was determined by the decibel (dB) scale from the Centers for Disease Control and Prevention. Results: Overall, 28% of the CoC hips experienced squeaking. The mean onset was 5.7 years postoperatively, with 39% of the cases having their onset more than 5 years after their THA. Patients with a lower body mass index were more likely to report squeaking (P = .009). The mean loudness of the squeak was 35 dB (range, 10-70 dB) and was loud in 36% of the hips. Patients who developed squeaking early postoperatively had louder squeaking than those with a later onset (P = .007). The loudness of the squeaking sound progressed in 25% of the cases, and these hips had louder squeaking (P = .04). Conclusions: Squeaking after CoC THA is not uncommon, can be relatively loud, and increases over time. This needs to be considered in young patients that are candidates for CoC THAs.

Local tissue concentrations of cefazolin during total joint arthroplasty: a systematic review.

BACKGROUND: Periprosthetic joint infections (PJI) following joint arthroplasty are now the leading cause of reoperation and are associated with serious morbidity to the patient, often requiring several staged operations and a prolonged course of parenteral antibiotics. Prophylactic administration of intravenous antibiotics before skin incision is arguably the most important measure to prevent PJI; however, the dose effectiveness of cefazolin in target tissue is not well known. We aimed to identify parameters affecting local tissue concentration (LTC) of cefazolin. METHODS: We performed a literature search using the following keywords: "orthopaedics," "orthopedic," "arthroplasty" and "cefazolin." We included studies that measured LTC of cefazolin from samples obtained during either a total knee or total hip arthroplasty. RESULTS: Of the 332 records screened, we included 10 studies that described LTC of cefazolin. The included studies evaluated dosing (n = 7), procedure type (n = 3), body mass index (n = 1) and tourniquet utilization (n = 1). CONCLUSION: Few studies have measured LTC levels of antibiotics (or levels of cefazolin) to validate current recommendations for antibiotic prophylaxis in orthopedic surgery. With infection as the leading reason for early reoperation or revision surgery, the parameters affecting LTC during orthopedic procedures need to be further assessed.

Revision Distal Femoral Replacement Using Custom-made Stem and Cone to Augment Proximal Fixation.

Achieving bone fixation during megaprosthesis revision presents a formidable challenge in view of the substantial bone loss. We report treatment of a failed revision distal femoral replacement in an active 36-year-old male mechanic remotely treated for osteosarcoma. A custom stem and cone were manufactured to augment fixation and preserve bone stock within a short segment of the remaining proximal femur. The patient returned to regular function without the need for assistive devices. Follow-up imaging demonstrated stable implant fixation at 1-year follow-up. While cones and sleeves have vastly improved fixation in revision knee arthroplasty, a custom-made cone for the proximal femur was used to augment fixation of a revision megaprosthesis and obviate the use of a total femoral replacement.

Decision making for early surgical technology adoption into Canada's healthcare system: a scoping review of the decision-making criteria, challenges, and opportunities.

OBJECTIVES: In 2020, Canada spent 12.9 percent of its GDP on healthcare, of which 3 percent was on medical devices. Early adoption of innovative surgical devices is mostly driven by physicians and delaying adoption can deprive patients of important medical treatments. This study aimed to identify the criteria in Canada used to decide on the adoption of a surgical device and identify challenges and opportunities. METHODS: This scoping review was guided by the Joanna Briggs Institute Manual for Evidence Synthesis and PRISMA-ScR reporting guidelines. The search strategy included Canada's provinces, different surgical fields, and adoption. Embase, Medline, and provincial databases were searched. Grey literature was also searched. Data were analyzed by reporting the criteria that were used for technology adoption. Finally, a thematic analysis by subthematic categorization was conducted to arrange the criteria found. RESULTS: Overall, 155 studies were found. Seven were hospital-specific studies and 148 studies were from four provinces with publicly available Web sites for technology assessment committees (Alberta, British Columbia, Ontario, and Quebec). Seven main themes of criteria were identified: economic, hospital-specific, technology-specific, patients/public, clinical outcomes, policies and procedures, and physician specific. However, standardization and specific weighted criteria for decision making in the early adoption stage of novel technologies are lacking in Canada. CONCLUSIONS: Specific criteria for decision making in the early adoption stage of novel surgical technologies are lacking. These criteria need to be identified, standardized, and applied in order to provide innovative, and the most effective healthcare to Canadians.

A Short Course of Celecoxib Prevents Heterotopic Ossification Following Cementless Total Hip Arthroplasty.

Heterotopic ossification (HO) is a common complication after total hip arthroplasty (THA) and can result in pain and loss of motion of the hip. This is the first study in the literature to determine if a short course of Celecoxib is effective in the prevention of HO in patients undergoing cementless THA. In this retrospective study of prospectively collected data, consecutive patients undergoing a primary cementless THA were reviewed at a 2-year follow-up. The Control group consisted of 104 hips that did not receive Celecoxib (Control group), while the 208 hips in the Celecoxib group received 100 mg twice daily for 10 days. Radiographs, patient-recorded outcome measures and range of motion (ROM) were evaluated. Overall, there was a significantly decreased incidence of HO in the Celecoxib group (18.7%) than in the Control group (31.7%) (p = 0.01). The odds that a patient developed HO using Celecoxib were 0.4965 times the odds that a patient developed HO without treatment. Clinically, the Celecoxib group demonstrated significantly greater improvement in their mean WOMAC stiffness (0.35 vs. 0.17, p = 0.02) and physical function scores (3.26 vs. 1.83, p = 0.03) compared to those in the Control group, but there was no difference in the ROM between the two groups. This study is the first to demonstrate that the lowest dose of Celecoxib for a short course of only 10 days is a simple and effective prophylactic treatment option that can significantly reduce the incidence of HO following cementless THA.

Five- to 12-Year Outcomes of a Short, Tapered, Highly Porous, Proximally Coated Cementless Femoral Stem.

BACKGROUND: Short cementless stems in total hip arthroplasty have gained increasing popularity, yet on-going studies of many of these implants are lacking. The aim of this study was to evaluate the minimum 5 year clinical and radiological results of a short, highly porous, single-tapered-wedge cementless femoral implant. METHODS: A retrospective study of 281 hips in 256 patients who had a minimum 5-year follow-up and underwent primary total hip arthroplasty between 2010 and 2016 were evaluated. Clinical and radiological results, complications, and the presence of postoperative thigh pain were evaluated. RESULTS: The mean follow-up was 8 years (range, 5 to 12 years). Clinically, patients had significant improvement in the average patient-related outcome scores postoperatively (Harris hip score: pre 47 versus post 95, University of California Los Angeles activity scale: pre 4 versus post 6, Western Ontario and McMaster Universities Arthritis Index: pre 51 versus post 3, Short Form (SF)-12 physical component summary : pre 32 versus post 52, Short Form-12 mental component summary: pre 49 versus post 55 (P < .001)). Radiographic signs of ingrowth were present in all hips. There were three patients (1.1%) who developed transient thigh pain postoperatively, all of which resolved with nonoperative management. CONCLUSION: This study provides the longest follow-up of this short, highly porous, single-tapered-wedge cementless femoral stem in the literature. This short, single-wedge stem with its highly porous coating demonstrated reproducible bone ingrowth in all patients and significant functional improvement with a very low rate of transient thigh pain.

Episode-of-care costs of total hip arthroplasty: day surgery versus same-day admission.

BACKGROUND: Although day surgery (DS) total hip arthroplasty (THA) has good patient satisfaction and a good safety profile, accurate episode-of-care cost (EOCC) calculations for this procedure compared to standard same-day admission (SDA) THA are not well known. We determined the EOCCs for patients who underwent THA, comparing DS and SDA pathways. METHODS: We evaluated the EOCCs for consecutive patients who underwent DS or SDA THA for osteoarthritis or osteonecrosis performed by a single surgeon at 1 academic centre from July 2018 to January 2020. Patient demographic and clinical data were recorded, as were preoperative diagnosis, type of anesthesia, type of implant used, surgical time and estimated blood loss. We determined direct and indirect costs from time of arrival at the presurgical unit to hospital discharge. We determined the EOCCs using an ABC method. RESULTS: The study included 50 patients who underwent THA (25 DS, 25 SDA). The mean length of stay in the SDA group was 45.1 (standard deviation [SD] 21.4) hours. Differences were observed between the 2 groups in mean age, mean Charlson Comorbidity Index score, surgical technique and mean surgical time (p ≤ 0.001). The mean total EOCC for SDA THA was $10 911 (SD $706.12, range $9944.07-$12 871.95), compared to $9672 (SD $546.55, range $8838.30-$11 058.07) for DS THA, a difference of 11.4%, mostly attributable to hospital resources such as laboratory tests, radiologic studies and cost of the surgical admission. CONCLUSION: Day surgery THA is cost-effective in selected patient populations. With the savings identified in this study, every 10 additional DS THA procedures would save sufficient resources to perform an additional THA operation.

Capsular Repair Counteracts the Risk of Dislocation in Hemiarthroplasty Conversion to Total Hip Arthroplasty.

This study investigated whether decreasing the femoral head size, in addition to performing a posterior capsular closure and short external rotator repair, influences the historical rate of dislocation after conversion of a failed hemiarthroplasty (HA) to a total hip arthroplasty (THA) through a posterior approach. We reviewed 15 patients from our prospective arthroplasty database who underwent a conversion from an HA to a THA with closure of the posterior capsule, had downsizing of the femoral head, and had at least a 2-year follow-up. Patients were clinically observed to determine whether their hip dislocated postoperatively or required re-revision. Radiographs were evaluated to assess for known risk factors for dislocation, including component position and restoration of hip biomechanics. The femoral head size was downsized from a mean of 45 mm (range, 42-57 mm) preoperatively to a mean of 32 mm (range, 28-36 mm) postoperatively (P<.001). Femoral heads sized 36, 32, and 28 mm were used in the revision of 4, 5, and 6 hips, respectively. At the mean 84-month follow-up (range, 24-156 months), there were no dislocations. Attention to surgical technique and closing the posterior capsule can decrease the historically high dislocation rate associated with converting an HA to a total hip replacement using the posterolateral approach. Despite substantial reduction in size of the prosthetic femoral head, there were no postoperative dislocations with closure of the posterior capsule. Downsizing the femoral head during revision THA should be avoided; however, if not feasible, closure of the posterior capsule can offset the otherwise increased risk of dislocation. [Orthopedics. 2023;46(3):175-179.].

Augmented Reality in Arthroplasty: An Overview of Clinical Applications, Benefits, and Limitations.

Augmented reality (AR) is a natural extension of computer-assisted surgery whereby a computer-generated image is superimposed on the surgeon's field of vision to assist in the planning and execution of the procedure. This emerging technology shows great potential in the field of arthroplasty, improving efficiency, limb alignment, and implant position. AR has shown the capacity to build on computer navigation systems while providing more elaborate information in a streamlined workflow to the user. This review investigates the current uses of AR in the field of arthroplasty and discusses outcomes, limitations, and potential future directions.

The Psychological Impact of COVID-19 on Arthroplasty Surgeons.

BACKGROUND: After the COVID-19 pandemic declaration in March 2020, all the elective total joint replacement surgeries in Canada were abruptly canceled for an indefinite period of time. The principal objective of this study was to determine the prevalence of psychological morbidity experienced by arthroplasty surgeons during the peak of the first wave of the COVID-19 pandemic. Secondary objectives included characterizing influential variables affecting the surgeon's well-being and suggesting directives for improvement. METHODS: This study surveyed Canadian Arthroplasty Society (CAS) members regarding their psychological well-being using the validated General Health Questionnaire (GHQ-12), the Center for Epidemiological Studies Depression (CES-D) scale, and the Personal Wellbeing Index-Adult (PWI-A). As well, the survey included questions regarding concerns about COVID-19, precautionary measures, personal well-being, and sociodemographic characteristics. RESULTS: A total of 80 surgeons (52% of those surveyed) completed the questionnaire, representing all 10 provinces in Canada. The prevalence of emotional distress and depression were 38% and 29%, respectively. Psychological morbidity most commonly resulted from concerns of loss of income/operating time, experiences of emotional conflict, and generalized safety worries. The surgeons commonly (93%) demonstrated insight in recognizing the impact of COVID-19 on their emotional health. CONCLUSION: Canadian arthroplasty surgeons demonstrated emotional resilience and insight during COVID-19. Continual communication, as well as remuneration action plans, could improve the mental well-being of at-risk individuals.

Hanging up the surgical cap: Assessing the competence of aging surgeons.

BACKGROUND: As the average age of surgeons continues to rise, determining when a surgeon should retire is an important public safety concern. AIM: To investigate strategies used to determine competency in the industrial workplace that could be transferrable in the assessment of aging surgeons and to identify existing competency assessments of practicing surgeons. METHODS: We searched websites describing non-medical professions within the United States where cognitive and physical competency are necessary for public safety. The mandatory age and certification process, including cognitive and physical requirements, were reported for each profession. Methods for determining surgical competency currently in use, and those existing in the literature, were also identified. RESULTS: Four non-medical professions requiring mental and physical aptitude that involve public safety and have mandatory testing and/or retirement were identified: Airline pilots, air traffic controllers, firefighters, and United States State Judges. Nine late career practitioner policies designed to evaluate the ageing physician, including surgeons, were described. Six of these policies included subjective performance testing, 4 using peer assessment and 2 using dexterity testing. Six objective testing methods for evaluation of surgeon technical skill were identified in the literature. All were validated for surgical trainees. Only Objective Structured Assessment of Technical Skills (OSATS) was capable of distinguishing between surgeons of different skill level and showing a relationship between skill level and post-operative outcomes. CONCLUSION: A surgeon should not be forced to hang up his/her surgical cap at a predetermined age, but should be able to practice for as long as his/her surgical skills are objectively maintained at the appropriate level of competency. The strategy of using skill-based simulations in evaluating non-medical professionals can be similarly used as part of the assessment of the ageing surgeons' surgical competency, showing who may require remediation or retirement.

Marital Relationship and Quality of Life in Couples Following Hip Replacement Surgery.

For the majority of patients with osteoarthritis, total hip (THA) arthroplasty results in a significant reduction in pain, emotional distress, and disability and a significant improvement in their quality of life. Little is known about how these recovery-related changes impact the spouse or the marital relationship. METHODS: Twenty-nine couples whose spouse underwent a THA (29 THA) participated in a semi-structured retrospective interview designed for this study. They were each asked to recall the level of pain before and after surgery and to provide a numerical rating score for questions pertaining to the level of disability in seven different activities of daily living. Couples were also asked to list in order of importance the five ways in which the surgery affected their overall quality of life. RESULTS: The spouses estimated their partner's pain, both pre- and postoperatively, to be significantly higher level than the patient's perception. The spouses perceived a greater improvement in family/home responsibilities, recreation and social activities, and in their occupation than that noted by the partner. After the arthroplasty, the spouses indicated that their lives had improved with respect to doing more activities/leisure (72%), because their partner had less suffering (59%), they had more independence/less caregiving (55%), it improved their marital relationship (52%), they had a better social/family life (28%), and they were able to travel (28%). CONCLUSIONS: This study indicates that THA result in a significant improvement in quality of life not only for the patients, but also for their spouses.

Restoration of Hip Biomechanics after a Hemiarthroplasty for a Femoral Neck Fracture-Who Does It Better?

INTRODUCTION: The restoration of the preoperative biomechanics of the hip, in particular leg length and femoral offset, are critical in restoring normal function and diminishing the risk of dislocation following hip arthroplasty. This study compares the consistency of arthroplasty and non-arthroplasty orthopedic surgeons in restoring the normal biomechanics of the hip when performing a hemiarthroplasty for the treatment of a femoral neck fracture. METHODS: We retrospectively reviewed the preoperative and postoperative digital radiographs of 175 hips that had a modular hemiarthroplasty for the treatment of a displaced femoral neck fracture at a Level 1 academic hospital. Fifty-two hips were treated by one of the three fellowship-trained arthroplasty surgeons (Group A), and 123 were treated by one of the nine non-arthroplasty fellowship-trained orthopedic surgeons (Group B). RESULTS: Patients in Group A were more likely to have their femoral offset restored to normal than patients in Group B, both with respect to under correcting the offset (p = 0.031) and overcorrecting the offset (p = 0.010). Overall, there was no difference in restoration of leg lengths between the two groups (p = 0.869). CONCLUSIONS: Following a hemiarthroplasty for a displaced femoral neck fracture, the normal biomechanics of the hip are more likely to be restored by an arthroplasty-trained surgeon than by a non-arthroplasty-trained surgeon. Identifying the inconsistency of non-arthroplasty surgeons and, to a lesser degree, arthroplasty surgeons in restoring hip biomechanics is important for sensitizing surgeons to rectify this in the future with appropriate templating and femoral implant selection.

Redesigning operating room booking in a tertiary care academic centre during the COVID-19 pandemic.

SUMMARY: With the closure of most operating rooms (ORs) during the coronavirus disease 2019 (COVID-19) pandemic, the traditional allocation of block OR time needed to be redesigned. An important factor permitting the treatment of patients in a prioritized fashion was our pre-existing centralized OR booking (CORB) framework, which already required surgeons to categorize the priority level for each patient. The CORB, in conjunction with the multidisciplinary OR oversight committee that was formed during COVID-19 to review and triage the urgent cases, allowed for prioritization of cases among surgical services. Centralized OR booking provided opportunities that were essential in OR planning during the pandemic, including the ability to plan surgeries to maximize OR efficiency, minimize the number of admissions on any given day to the wards and the intensive care unit, flatten the number of admissions over the week and provide the flexibility to ramp up or down the number of ORs as the crisis changed.

Improving ergonomics in the operating room for orthopaedic surgeons in order to reduce work-related musculoskeletal injuries.

INTRODUCTION: Orthopaedic surgery is characterized by surgical tasks that are physical, repetitive and require some degree of stamina from the surgeon. Occupational injuries are alarmingly common in orthopaedic surgery with two-thirds of all surgeons reporting a work-related musculoskeletal (MSK) injury during their career. One of the leading causes of the high level of MSK injuries among orthopaedic surgeon is lack of ergonomics of the operating room. Implementing an ergonomic process has been shown to be effective in reducing the risk of developing MSK disorders in other high-risk industries. We reviewed well-established and effective ergonomic guidelines from the industrial workplace and determined the pertinent principles that could be transferred to the operating room to help reduce the number and severity of common orthopaedic work-related MSK injuries. METHODS: We reviewed the ergonomic guidelines, primarily from the Occupational Safety and Health Administration (OSHA), that specifically address minimizing the risk of these work-related injuries and that are transferable to the operating room. In addition, the ergonomic guidelines from the Canadian Center for Occupational Health and Safety (CCOHS), the National Institute for Occupational Safety and Health (NIOSH) and the Centers for Disease Control and Prevention (CDC) were reviewed. RESULTS: Many of the guidelines to avoid work-related injuries in industry are transferable to the operating room. The pertinent guidelines clearly indicated how to adjust the height of the operating table, the proper design of hand and power tools and the modifications to the operating room environment that can help prevent injury. These guidelines from industry include maintaining a neutral posture and joint alignment, working with the appropriate hand tools and minimizing the lower extremity fatigue by using the proper footwear and floor mats. DISCUSSION: Optimizing the occupational environment and utilizing well-established ergonomic principle from industry is both feasible and practical in the operating room to decrease the incidence of musculoskeletal injuries among this high-risk profession. These guidelines are simple, effective and are easy to implement by orthopaedic surgeons in order to minimize their risk of sustaining a work-related injury.

Topology optimization of 3D-printed structurally porous cage for acetabular reinforcement in total hip arthroplasty.

Aseptic loosening and mechanical failure of acetabular reinforcement components are among the main causes of their reduced service life. Current acetabular implants typically feature a structural solid layer that provides load bearing capacity, coated with a foam of uniform porosity to reduce stress shielding and implant loosening. This paper presents an alternative concept for a 3D printed cage that consists of a multifunctional fully porous layer with graded attributes that integrate both structural function and bone in-growth properties. The design comprises a hemispherical cup affixed to a superior flange with architecture featuring an optimally graded porosity. The methodology here presented combines an upscaling mechanics scheme of lattice materials with density-based topology optimization, and includes additive manufacturing constraints and bone ingrowth requirements in the problem formulation. The numerical results indicate a 21.4% reduction in the maximum contact stress on the bone surface, and a 26% decrease in the bone-implant interface peak micromotion, values that are indicative of enhanced bone ingrowth and implant long-term stability.