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There is an increasing demand for a suitable bone substitute to replace current clinical gold standard autografts or allografts. Majority of previous studies have focused on the early effects of substitutes on bone formation, while information on their long-term efficacies remains limited. This study investigated the efficacies of natural hydroxyapatite (nHA) derived from oyster shells and synthetic hydroxyapatite mixed with collagen (COL/HA) or chitosan (CS/HA) on bone regeneration and implant fixation in sheep. Titanium implants were inserted into critical-size defects in distal femur condyles bilaterally, and circumferential gaps around implants were filled with substitute materials or allografts (as control). 14 or 24 weeks post-operatively, the implant-bone blocks were harvested and evaluated using microarchitectural, histomorphometric, and mechanical methods. The nHA and COL/HA groups showed significant bone formation at both 14 and 24 weeks. There was a pronounced increase in bone tissue volume and ingrowth into titanium implant’s porous surfaces, significantly enhancing mechanical fixation strength at 24 weeks. CS/HA had a limited ability to induce bone formation and implant fixation. We conclude that nHA and COL/HA revealed long-term effects on enhancing bone formation and implant fixation that were at least as good as allograft after 24 weeks, and both nHA and COL/HA appear to be good alternative materials to bone allograft. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the biomechanical contributions of the nail and the plate individually to a complete nail‐plate construct in the setting of comminuted distal femur fractures. For this biomechanical study, comminuted extra‐articular distal femur fractures were created in 24 synthetic osteoporotic femur models. These were then split into three groups: the nail‐only group, the plate‐only group, and the nail‐plate group. After fixation, each specimen underwent sequential axial and torsional loading, and axial and torsional stiffness were calculated and compared. The addition of a nail to a plate‐only construct increased axial stiffness by 19.7% and torsional stiffness by 59.4%. The plate‐only group and nail‐plate group both demonstrated significantly greater axial and torsional stiffness than the nail‐only group at all levels of axial and torsional load. (p < 0.001) At 1000 and 2000 N of cyclic loading, the nail‐plate group demonstrated significantly greater axial stiffness than the plate‐only group (p ≤ 0.018). The nail‐plate group demonstrated greater torsional stiffness than the plate‐only groups at all levels of torsional loading (p < 0.001). In osteoporotic comminuted distal femur fracture models, most of the axial stiffness in a nail‐plate construct comes from the plate. While the combination of the two constructs is not fully additive, the plate contributes the majority of the axial and torsional stiffness in a nail‐plate construct. The supplementation of the plate with a nail primarily helps to increase resistance to rotational forces. Level of Evidence: III. [ABSTRACT FROM AUTHOR]

Percutaneous Osseointegrated Implants (POI) affix artificial limbs to the body after amputation. Several adverse events challenge mainstream uptake of this technology. This study aims to achieve a consensus regarding "the challenges and adverse events to POI integration and long-term fixation in limb amputation". We sought a panel of clinical experts divided by profession into surgical, clinical, or clinical academic categories. We used a real time eDelphi method to develop consensus on both the challenges and adverse event items, enabling anonymity, iteration, controlled feedback, and statistical aggregation of group responses. The full panel agreed that the most impactful items are amongst 10 key challenges and eight adverse events. Panellists were in consensus regarding the five most impactful challenges, which were, in decreasing order: patient selection, absence of a multidisciplinary team, design of the implant, soft tissue stability and an experienced surgical team. Panellists considered the five most impactful adverse events, in decreasing order, to be the following: no biological fixation, deep infection, aseptic loosening, no mechanical fixation, and implant breakage. Consensus was obtained on implant breakage and deep infection items. The proportion of consensus from the whole panel across all items was in line with the literature, and we observed an improvement in consensus once the panel was stratified based on job, expertise and implant system. [ABSTRACT FROM AUTHOR]

Cementless total knee arthroplasty (TKA) has regained interest for its potential for long-term biologic fixation. The density of the bone is related to its ability to resist static and cyclic loading and can affect long-term implant fixation; however, little is known about the density distribution of periarticular bone in TKA patients. Thus, we sought to characterize the bone mineral density (BMD) of the proximal tibia in TKA patients. We included 42 women and 50 men (mean age 63 years, range: 50 to 87; mean body mass index 31.6, range: 20.5 to 49.1) who underwent robotic-assisted TKA and had preoperative computed tomography scans with a BMD calibration phantom. Using the robotic surgical plan, we computed the BMD distribution at 1 mm-spaced cross-sections parallel to the tibial cut from 2 mm above the cut to 10 mm below. The BMD was analyzed with respect to patient sex, age, preoperative alignment, and type of fixation. The BMD decreased from proximal to distal. The greatest changes occurred within ± 2 mm of the tibial cut. Age did not affect BMD for men; however, women between 60 and 70 years had higher BMD than women ≥ 70 years for the total cut (P =.03) and the medial half of the cut (P =.03). Cemented implants were used in 1 86-year-old man and 18 women (seven < 60 years, seven 60 to 70 years, and four ≥ 70 year old). We found only BMD differences between cemented or cementless fixation for women < 60 years. To our knowledge, this is the first study to characterize the preoperative BMD distribution in TKA patients relative to the intraoperative tibial cut. Our results indicate that while sex and age may be useful surrogates of BMD, the clinically relevant thresholds for cementless knees remain unclear, offering an area for future studies. [ABSTRACT FROM AUTHOR]

Copyright of Die Orthopädie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fixation with suture anchors and metallic hardware for osteosynthesis is common in orthopedic surgeries. Most metallic commercial bone anchors achieve their fixation to bone through shear of the bone located between the threads. They have several deficiencies, including stress‐shielding due to mechanical properties mismatch, generation of acidic by‐products, poor osteointegration, low mechanical strength and catastrophic failure often associated with large bone defects that may be difficult to repair. To overcome these deficiencies, a swelling porous copolymeric material, to be used as bone anchors with osteointegration potential, was introduced. The purpose of this study was to investigate the fixation strength of these porous, swelling copolymeric bone anchors in artificial bone of various densities. The pull‐out and subsidence studies indicate an effective fixation mechanism based on friction including re‐fixation capabilities, and minimization of damage following complete failure. The study suggests that this swelling porous structure may provide an effective alternative to conventional bone anchors, particularly in low‐density bone. [ABSTRACT FROM AUTHOR]

Abstract Custom-made triflange acetabular implants are increasingly used in complex revision surgery where supporting bone stock is diminished. In most cases these triflange cups induce stress-shielding. A new concept for the triflange is introduced that uses deformable porous titanium to redirect forces from the acetabular rim to the bone stock behind the implant and thereby reduces further stress-shielding. This concept is tested for deformability and primary stability. Three different designs of highly porous titanium cylinders were tested under compression to determine their mechanical properties. The most promising design was used to design five acetabular implants either by incorporating a deformable layer at the back of the implant or by adding a separate generic deformable mesh behind the implant. All implants were inserted into sawbones with acetabular defects followed by a cyclic compression test of 1800N for 1000 cycles. The design with a cell size of 4 mm and 0.2 mm strut thickness performed the best and was applied for the design of the acetabular implants. An immediate primary fixation was realized in all three implants with an incorporated deformable layer. One of the two implants with a separate deformable mesh needed fixation with screws. Cyclic tests revealed an average additional implant subsidence of 0.25 mm that occurred in the first 1000 cycles with minimal further subsidence thereafter. It is possible to realize primary implant fixation and stability in simulated large acetabular revision surgery using a deformable titanium layer behind the cup. Additional research is needed for further implementation of such implants in the clinic.

The Orthopaedic Research Society's Research Interest Group completed its international consensus meeting (ICM) on musculoskeletal infections (MSKI) following the 2023 Annual Meeting. The work products from this ICM include the 65 questions with recommendation and rationale, and the voting results from the 72 delegates. There are also five Consensus Articles in this issue of the Journal of Orthopaedic Research from the ICM Sections: Host Immunity, Established Infection‐Treatment, Clinical Questions not addressed by the prior MSKI ICMs, In Vitro, and Animal Models. This Introduction summarizes the 3‐year Delphi process used by the ICM with timelines and critical milestones. It also highlights several challenges that had to be addressed, and a large body of work that remains. [ABSTRACT FROM AUTHOR]

Total disc replacements utilize textured coatings to maximize bony ongrowth. However, the contribution of direct bony attachment to overall fixation for total disc replacements has not been reported. The goal of the present study was to document the extent of bony attachment to the surfaces of two clinically functional total disc replacements that were securely fixed at the time of revision. Two metal‐and‐polymeric disc replacements, one cervical and one lumbar, were evaluated following surgical retrieval. The cervical device was retrieved at 8 months and the lumbar device at 28 months post‐operative. Both devices were reported well‐fixed at the time of removal, with large bone masses attached to one endplate of each device. Visual inspections, non‐destructive gravimetric measurements, and surface metrology were performed to assess fixation. These inspections suggested that both devices had been fixed at the time of removal with little in vivo mechanical damage, as surgical extraction damage was noted on both devices and provided imaging showed a lack of device migration. Devices were then embedded and sectioned to evaluate the bone‐implant interface. High resolution photographs and contact microradiographs were taken to assess bony attachment. In contrast to initial analysis, these images revealed radiolucent gaps between the endplates and bone masses. Little direct contact between the bone and endplate surface was identified and the original surgical cuts were still visible. Both devices were clinically fixed at the time of removal and neither had complications associated with loosening. However, osseointegration was minimal in one of the devices and altogether absent from the other. The findings of the present study suggest that other factors may influence overall clinical fixation such as the surgical preparation of the vertebral bone or the surface roughness of the treated endplates. Despite the limitations of the present study, this information is unique to the current total disc replacement literature and the ongrowth and fixation of devices should be considered as a topic for future investigation. [ABSTRACT FROM AUTHOR]

Custom-made triflange acetabular implants are increasingly used in complex revision surgery where supporting bone stock is diminished. In most cases these triflange cups induce stress-shielding. A new concept for the triflange is introduced that uses deformable porous titanium to redirect forces from the acetabular rim to the bone stock behind the implant and thereby reduces further stress-shielding. This concept is tested for deformability and primary stability. Three different designs of highly porous titanium cylinders were tested under compression to determine their mechanical properties. The most promising design was used to design five acetabular implants either by incorporating a deformable layer at the back of the implant or by adding a separate generic deformable mesh behind the implant. All implants were inserted into sawbones with acetabular defects followed by a cyclic compression test of 1800N for 1000 cycles. The design with a cell size of 4 mm and 0.2 mm strut thickness performed the best and was applied for the design of the acetabular implants. An immediate primary fixation was realized in all three implants with an incorporated deformable layer. One of the two implants with a separate deformable mesh needed fixation with screws. Cyclic tests revealed an average additional implant subsidence of 0.25 mm that occurred in the first 1000 cycles with minimal further subsidence thereafter. It is possible to realize primary implant fixation and stability in simulated large acetabular revision surgery using a deformable titanium layer behind the cup. Additional research is needed for further implementation of such implants in the clinic. [ABSTRACT FROM AUTHOR]

This study investigated the presence and progression of radiolucent lines (RLLs) after cemented total knee arthroplasty (TKA) with or without tourniquet use. There were 369 consecutive primary cemented TKAs with 5 to 8 years of follow-up. A tourniquet was used during component cementation in patients who underwent surgery from January 3, 2006, to March 31, 2010. No tourniquet was used from August 14, 2009, to October 14, 2014. There were 192 patients in the tourniquet group (TQ) and 177 patients in the no tourniquet group (NQ). Patient demographics, reoperations, and complications were recorded. RLLs were identified on anteroposterior, lateral, and skyline x-rays at 1, 2, and 5 to 8 years postoperatively using the modern knee society radiographic evaluation system. Demographics, reoperations, complications, and RLLs were compared. Age, sex, and body mass index were similar between groups. Mean tourniquet time in TQ was 11 minutes (range, 8 to 25). The presence of RLLs differed between groups, with 65% of TQ knees having RLLs under any part of the prostheses versus 46% of NQ knees (P <.001). The progression of RLL >2 mm occurred in 26.0% of knees in TQ and 16.7% of knees in NQ (P =.028). There were 13 TKAs that underwent subsequent revision surgery. There was no statistically or clinically significant difference in revision rate between groups (7 revisions in TQ, 6 in NQ, P =.66). Less RLLs were identified in NQ versus TQ. There were no statistically or clinically significant differences in revision rates between the NQ and TQ groups at 5 to 8 years. [ABSTRACT FROM AUTHOR]

The stability in an implant fixation plays a vital role in ensuring proper formation and remodelling process of the fractured bone. Failure in implant fixation is commonly associated with short- and long-term instability of the bone-implant interface. The bone-implant interaction creates a complicated mechanical interplay that might influence the stress distribution and hence the biomechanical performance stability of the implant fixation. Furthermore, implant screw parameters namely thread size, geometrical design and material properties become additional factors that affect the bone-implant interaction. The purpose of this study was to investigate the effect of unicortical and bicortical screws' parameters on the screw-bone interaction mechanism. To evaluate the stress transfers between screw and bone, the stress parameters namely stress transfer parameters (STP) was employed. A two-dimensional (2D) finite element model of full treaded screw was simulated while varying the parameters of the screw: two types of material (stainless steel A316 and titanium alloy Ti-6Al-4V), screw length and screw pitch. It was found that the lower in elastic modulus results to the higher stress transfer between implantbone interface. As the titanium have lower elastic modulus, it gave higher values of STP which help to transmit and distribute stress better compared to the stainless steel. While the effect of varying screw pitch between two types of screws shows that STPs values of fully threaded bicortical screws shows significant result for finer pitch size that may advancing bone remodelling process at the early stage. [ABSTRACT FROM AUTHOR]

Proximal femur fractures in the elderly are associated with significant loss of independence, mobility, and quality of life. This prospective study aimed to: (1) investigate gait biomechanics in intertrochanteric fracture (ITF) patients (A1 and A2 AO/OTA) managed via femoral nailing at 6 weeks and 6 months postoperative and how these compared with similarly aged elderly controls; and (2) investigate whether femoral offset shortening (FOS) and lateral lag screw protrusion (LSP) were associated with changes in gait biomechanics at postoperative time points. Hip radiographs and gait data were collected for 34 patients at 6 weeks and 6 months postoperatively. Gait data were also collected from similarly aged controls. FOS and LSP were measured from radiographs. Joint angles, external moments, and powers were calculated for the hip, knee, and ankle and compared between time points in ITF patients and healthy controls using statistical parametric mapping. The relationship between radiographic measures with gait speed, step length, peak hip abduction, and maximum hip abduction moment was assessed using a Pearson correlation. External hip adduction moments and hip power generation improved in the first 6 months postoperative, but differed significantly from healthy controls during single limb stance. LSP showed a moderate correlation with maximum hip abduction moment at 6 weeks postoperative (r = −0.469, p = 0.048). These results provide new detail on functional outcomes after ITF and potential mechanisms that functional deficiencies may stem from. Lag screw prominence may be an important factor in maintaining functional independence and minimizing the risk of secondary falls after ITF in the elderly. [ABSTRACT FROM AUTHOR]

This study investigated the effect of romosozumab on bone union in a rat posterolateral lumbar fixation model. Posterolateral lumbar fixation was performed on 8‐week‐old male Sprague Dawley rats (n = 20). For bone grafting, autogenous bone (40 mg) was harvested from the spinous processes of the 10th thoracic vertebra until the 2nd lumbar vertebra and implanted between the intervertebral joints and transverse processes of the 4th and 5th lumbar vertebrae on both sides. Rats were matched by body weight and equally divided into two groups: R group (Evenity®, 25 mg/kg) and control (C) group (saline). Subcutaneous injections were administered twice a week until 8 weeks after surgery. Computed tomography was performed at surgery and week 8 after surgery. The area and percentage of bone trabeculae in the total area of bone fusion were calculated. Statistical analysis was performed using an unpaired t test (p < 0.05). We found that the R group rats had significantly higher mean bone union rate and volume than did the C group rats at all time courses starting week 4 after surgery. The R group had significantly higher increase rates than did the C group at weeks 4 and 6 after surgery. The percentage of bone trabeculae area in the R group was approximately 1.7 times larger than that in the C group. Thus, we demonstrated that romosozumab administration has stimulatory effects on bony outgrowth at bone graft sites. We attribute this to the modeling effect of romosozumab. [ABSTRACT FROM AUTHOR]

Aseptic loosening remains one of the top causes of revision surgery of total knee arthroplasty (TKA). Radiostereometric analysis (RSA) is used in research to measure implant migration, however limitations prevent its clinical use. New methods have allowed the same measurements as RSA to be performed with computed tomography (CT) scanners (CT-RSA). The objective of this study is to determine inducible displacement measurements from weight-bearing computed tomography (WBCT) and conventional RSA to assess implant stability. Participants (n = 17) completed RSA exams in the supine and standing position, and WBCT exams in the seated (leg extended) and standing position. Double examinations were performed in the seated (WBCT) or supine (RSA) positions. Inducible displacements were measured with model-based RSA (MBRSA) for RSA exams, and a novel CT-RSA software, V3MA, for WBCT exams. Precision of each technique was calculated between double examinations. Precision data for tibial component total translations and rotations were 0.05 mm and 0.118°, respectively with WBCT-RSA, and were 0.108 mm and 0.269°, respectively with MBRSA. MTPM precision was 0.141 mm with WBCT-RSA and was 0.168 mm with MBRSA. Inducible displacement MTPM of the tibial component was 0.244 ± 0.220 mm with WBCT-RSA and 0.662 ± 0.257 mm with MBRSA. Inducible displacement measurements with MBRSA were significantly different from WBCT-RSA for tibial component anterior tilt (p = 0.0002). WBCT-RSA demonstrated comparable precision to MBRSA, and both techniques measured inducible displacements consistent with stable components. Clinical Significance: As the availability of WBCT increases, its use as an alternative to MBRSA is supported to measure the instantaneous fixation of implant components., (© 2024 The Author(s). Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Aims: We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants. Methods: An established allografted revision protocol was implemented bilaterally into the stifle joints of 24 canines. At revision surgery, each animal received one BMP-2 (5 µg) functionalized implant, and one raw implant. One group (12 animals) received bone graft impregnated with zoledronate (0.005 mg/ml) before impaction. The other group (12 animals) received untreated bone graft and systemic zoledronate (0.1 mg/kg) ten and 20 days after revision surgery. Animals were observed for an additional four weeks before euthanasia. Results: No difference was detected on mechanical implant fixation (load to failure, stiffness, energy) between local or systemic zoledronate. Addition of BMP-2 had no effect on implant fixation. In the histomorphometric evaluation, implants with local zoledronate had more area of new bone on the implant surface (53%, p = 0.025) and higher volume of allograft (65%, p = 0.007), whereas implants in animals with systemic zoledronate had the highest volume of new bone (34%, p = 0.003). Systemic zoledronate with BMP-2 decreased volume of allograft by 47% (p = 0.017). Conclusion: Local and systemic zoledronate treatment protects bone at different stages of maturity; local zoledronate protects the allograft from resorption and systemic zoledronate protects newly formed bone from resorption. BMP-2 in the dose evaluated with experimental revision implants was not beneficial, since it significantly increased allograft resorption without a significant compensating anabolic effect.

Copyright of Der Unfallchirurg is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A solution for challenging hip dysplasia surgery could be a patient‐specific 3D‐printed shelf implant that is positioned extra‐articular and restores the dysplastic acetabular rim to normal anatomical dimensions. The anatomical correction and biomechanical stability of this concept were tested in a canine model that, like humans, also suffers from hip dysplasia. Using 3D reconstructed computed tomography images the 3D shelf implant was designed to restore the radiological dysplastic hip parameters to healthy parameters. It was tested ex vivo on three dog cadavers (six hips) with hip dysplasia. Each hip was subjected to a biomechanical subluxation test, first without and then with the 3D shelf implant in place. Subsequently, an implant failure test was performed to test the primary implant fixation. At baseline, the dysplastic hips had an average Norberg angle of 88 ± 3° and acetabular coverage of 47 ± 2% and subluxated at an average of 83 ± 2° of femoral adduction. After adding the patient‐specific shelf implants the dysplastic hips had an average Norberg angle of 122 ± 2° and acetabular coverage of 67 ± 3% and subluxated at an average of 117 ± 2° of femoral adduction. Implant failure after primary implant fixation occurred at an average of 1330 ± 320 Newton. This showed that the patient‐specific shelf implants significantly improved the coverage and stability of dysplastic hips in a canine model with naturally occurring hip dysplasia. The 3D shelf is a promising concept for treating residual hip dysplasia with a straightforward technology‐driven approach; however, the clinical safety needs to be further investigated in an experimental proof‐of‐concept animal study. [ABSTRACT FROM AUTHOR]

The need for a substitute for allograft and autograft is rising as bone graft surgeries exceed available supplies. We investigated the efficacy of the low‐molecular weight marine bioactive compound fucoidan (FUC) on bone regeneration and implant fixation in seven female sheep, as FUC has shown great promise as a bone substitute. Titanium implants were inserted bilaterally in the distal femurs to test three hydroxyapatite/fucoidan (HA/FUC) groups and compared to allograft. The HA was coated with either 500 or 1500 μg of FUC, obtained by microwave‐assisted chemical extraction, or 500 μg of FUC obtained by an enzyme‐assisted extraction method. The concentric 2‐mm gap around the implant was filled with either one of the HA/FUCs or allograft from the donor sheep. After 12 weeks, implant–bone blocks were harvested and divided into three parts for mechanical push‐out testing, immunohistochemistry, and micro‐CT and histomorphometry. Pronounced bone formations were observed by micro‐CT and histomorphometry in all groups, but higher bone volume fractions were seen in the allograft group compared to the three HA/FUC groups. The trabecular thickness, trabecular separation, and architectural anisotropy were all significantly higher in the allograft group compared to the three HA/FUC groups. In conclusion, adequate bone formation was observed in all groups, although the bone formation was significantly greater in the allograft group. Also, no significant differences existed in the shear mechanical properties between groups, suggesting that the combination of HA and FUC can achieve a similar fixation strength to allograft in this model. [ABSTRACT FROM AUTHOR]

Purpose: It is essential to have sufficient bone bulk and density at the implant site in order to achieve good bone-to-implant contact and primary stability, which are crucial for osseointegration. A new osteotomy preparation technique was recently introduced that uses a bone preservation method that creates a layer of compacted bone along the surface of the osteotomy. The hypothesis of this study was that this novel technique would increase primary implant stability, bone mineral density, and the percentage of bone at the implant surface compared with drilling technique. Materials and Methods: A total of 72 osteotomies were created in porcine tibial plateau bone samples using three preparation techniques: standard drilling; osseous extraction drilling with a new tapered, multi-fluted bur design; and osseous densification with the same multi-fluted bur rotating in a reversed direction that preserved and created a compacted layer of bone. The surgical process (temperature increase, drilling force, and torque), mechanical stability during the insertion and removal of 4.1-mm and 6.0-mm diameter implants (implant torque and stability quotient), and bone imaging (scanning electron microscopy, microcomputed tomography measurement of bone mineral density, and histomorphology) were compared among the three preparation techniques. Results: Osseous densification significantly increased insertion and removal torques compared to standard drilling or extraction drilling. No significant differences in implant stability quotient readings or temperature increases were demonstrated among the three groups. Although the same bur was used for extraction drilling and osseous densification techniques, the osseous densification osteotomy diameters were smaller than both the extraction drilling and standard drilling osteotomies due to the spring-back effect of bone elastic strain created. Imaging methods documented a layer of increased bone mineral density around the periphery of osseous densification osteotomies. The percentage of bone at the implant surface was increased by approximately three times for implants prepared with osseous densification compared with standard drilling. Conclusion: This study confirmed the hypothesis that the osseous densification technique would increase primary stability, bone mineral density, and the percentage of bone at the implant surface compared with drilling. By preserving bulk bone, it is hypothesized that the healing process will be accelerated due to the bone matrix, cells, and biochemicals that are maintained in situ and autografted along the surface of the osteotomy site. The healing response requires further study in vivo. [ABSTRACT FROM AUTHOR]

Background: Hip and knee implants can either be fixed without cement, press-fit, or with bone cement. Real-world data from arthroplasty registers, as well as studies provide a broad database for the discussion of cemented versus uncemented arthroplasty procedures., Objective: What does current evidence from international arthroplasty registries and meta-analyses recommend regarding cemented or cementless fixation of hip and knee implants?, Methods: A recommendation is generated by means of direct data comparison from the arthroplasty registries of eight countries (USA, Germany, Australia, UK, Sweden, Norway, New Zealand, Netherlands), the comparison of 22 review studies and meta-analyses based on registry data, as well as an evaluation of recommendations of healthcare systems from different nations. For this purpose, reviews and meta-analyses were selected where the results were statistically significant, as were the annual reports of the arthroplasty registries that were current at the time of writing., Results: For knee arthroplasties, long survival time as well as lower risk of revision can be achieved with the support of cemented fixation with antibiotic-loaded bone cement. In patients aged 70 years and older, cemented fixation of hip stem implants significantly reduces risk of intraoperative or postoperative periprosthetic fracture (quadruple). This applies both to elective total hip arthroplasties and to hemiarthroplasty after femoral neck fractures. Antibiotic-loaded bone cement significantly (p = 0.041) reduces the risk of periprosthetic infection, especially in patients with femoral neck fractures., Conclusion: Total knee replacement with antibiotic-loaded bone cement is well established internationally and is evidence-based. Registry data and meta-analyses recommend cemented fixation of the hip stem in older patients. In Germany, USA and Australia these evidence-based recommendations still must be transferred to daily practice., (© 2024. The Author(s).)

Introduction: Aseptic tibial loosening is now considered the most common reason that total knee arthroplasties (TKA) fail long term. There are unique subsets of patients that fail into varus alignment of the tibial tray with collapse of the medial proximal tibia. It is currently unknown if the implant fixation fails first or if the proximal medial tibia collapses first.Materials: We performed a retrospective analysis of 88 patients that were revised at our institution secondary to aseptic varus collapse of the proximal tibia. Two fellowship-trained arthroplasty surgeons performed a retrospective analysis on sequential precollapse radiographs in each patient to determine which failed first: the implant fixation (implant-cement or cement-bone interface) or the medial proximal tibia.Discussion: 36/88 (40.9%) patients had a series of precollapse radiographs that could be reviewed. Failure at the implant-cement interface before varus collapse in 23 vs 22 patients, failure at the implant-cement and cement-bone interface before varus collapse in two patients, and contemporaneous failure at the implant-cement interface and varus collapse in 11 vs 12 patients were identified by reviewers one and two, respectively.Conclusion: The most frequent mechanism of failure identified was failure of the implant-cement interface followed by subsequent medial tibial varus collapse. Improving implant fixation may decrease the incidence of this unique failure mechanism. We advocate the use of supplemental stem fixation in high-risk patients and optimal cement techniques for all patients as methods of potentially avoiding tibial varus collapse, one of the most frequent modes of long-term failure. [ABSTRACT FROM AUTHOR]

The sacroiliac joint (SIJ) is a known pain generator that, in severe cases, may require surgical fixation to reduce intra‐articular displacements and allow for arthrodesis. The objective of this computational study was to analyze how the number of implants affected SIJ stabilization with patient‐specific characteristics such as the pelvic geometry and bone quality. Detailed finite element models were developed to account for three pelvises of differing anatomy. Each model was tested with a normal and low bone density (LD) under two types of loading: compression only and compression with flexion and extension moments. These models were instrumented with one to three cylindrical, threaded and fenestrated implants through a posterior oblique trajectory, requiring less muscle dissection than the more common lateral trajectory used with triangular implants. Compared with the noninstrumented pelvis, the change in range of motion (ROM) and stress distribution were used to characterize joint stabilization. Noninstrumented mobility ranged from 0.86 to 2.55 mm and from 1.37° to 6.11°. Across patient‐specific characteristics, the ROM reduction with one implant varied from 3% to 21% for vertical and 15% to 47% for angular displacements. With two implants, the ROM reduction ranged from 12% to 41% for vertical and from 28% to 61% for angular displacements. Three implants, however, did not further improve the joint stability (14% to 42% for vertical and 32% to 63% for angular displacements). With respect to patient characteristics, an LD led to a decreased stabilization and a higher volume of stressed bone (>75% of yield stress). A better understanding of how patient characteristics affect the implant performance could help improve surgical planning of sacroiliac arthrodesis. [ABSTRACT FROM AUTHOR]

Morphologic analysis of the proximal humerus has been performed to provide information about regions of best bone quality for stemless implant fixation. However, implant design-related bone analysis regarding primary fixation strength has not been reported. The purpose of this study was to investigate bone volume fraction (BV/TV) and bone mineral density (BMD) in the spatial vicinity of humeral implant fixation and biomechanical performance following placement of two different stemless RSA designs. It was hypothesized that peripheral expandable implant fixation (PEF) would result in residual peri-implant bone with higher BMD and BV/TV and higher fixation strength compared to a central-hexagonal impaction fixation (CHIF) design. Overall 25 human cadavers were prepped for stemless RSA using either a CHIF (n = 5) or PEF design (n = 20). Micro computed tomography scans were obtained post-preparation to analyze overall BV/TV and BMD in the anchoring region of 2 stemless implant designs. Bone volumes of paired specimens (each group n = 5) were further segmented and divided into three even planar subsections along the implantation direction with four additional radial sectors, each according to their anterior-posterior and medial-lateral direction. Following implantation, biomechanical testing was performed to evaluate ultimate failure load and stiffness of the 2 implants. Postpreparation paired humeral bone analysis revealed significantly greater residual peri-implant BMD (P <.026) and higher BV/TV for PEF. Overall linear correlation between residual BMD and BV/TV showed good coefficients of determination (R2 > 0.69) with significantly higher bone density for PEF (P =.003). Further division in proximal to distal planar subsections of paired specimens showed overall statistically higher BMD and BV/ TV for PEF (at least P <.002). Except from the posterior sector, BMD and BV/TV of overall and specific radial sectors within planar subvolumes were significantly higher for PEF. Biomechanical testing revealed increased ultimate loads (−818 ± 282 N vs. −535 ± 144 N; P =.081) and stiffness (898 ± 106 N/mm vs. 431 ± 121 N/mm; P <.001) with smaller tilting angles at failure for PEF compared to CHIF. A linear relationship between normalized failure load by the implant size and combined bone parameter (BV/TV*BMD) provided an accuracy in the order of R2 > 0.89 with significantly higher primary stability for PEF (P =.046). Implant design in stemless RSA affects residual bone quality in the anchoring region and primary fixation strength. Peripheral implant anchoring along the insertion direction provides significantly higher residual peri-implant BMD and BV/TV to achieve improved primary fixation with a radial expandable anchoring implant compared to a central-hexagonal impacted design. Basic Science Study; Anatomy Study; Imaging; Biomechanics [ABSTRACT FROM AUTHOR]

Introduction: Surgically balanced total knee arthroplasties have shown improved functional and clinical outcomes. Two different alignment methods have been proposed, the measured resection technique which uses femoral landmarks on the one hand and the ligament balanced technique which uses spreaders on the other. As anatomical landmarks also vary widely, with regards to the tibial cut irrespective of the collateral ligaments, we hypothesized that anatomical landmarks are not suitable for ideal femoral component rotational alignment. Materials and methods: Ten cadaveric bilateral knees underwent TKA using a navigational device and a double tensiometer. By means of the navigational device, flexion gaps were balanced by femoral component size, rotation and flexion until a symmetric flexion and extension gap was obtained. Acquired femoral component rotation was compared to femoral landmarks (Whiteside Line, posterior condylar line and trans-epicondylar line). Results: Using the Whiteside line, the posterior condylar line and the surgical trans-epicondylar line to identify femoral component rotation did not balance the flexion gap as well as navigation. Depending on the parameter, deviations in femoral rotation of up to 6° were observed compared to the gap balancing technique. Furthermore, large deviations between these landmarks were observed. Conclusion: Based on this study flexion gap balancing can be better optimized using ligament balancing technique. As this technique is highly dependent on the proximal tibial cut, we do recommend the use of navigational devices, which additionally assure a neutral leg alignment. [ABSTRACT FROM AUTHOR]

Background: This study aims to present an overview and critical appraisal of all previous studies comparing costs and outcomes of the different modes of fixation in total hip arthroplasty (THA). A secondary aim is to provide conclusions regarding the most cost-effective mode of implant fixation per gender and age-specific population in THA, based on high quality studies. Methods: A systematic search was conducted to identify cost-effectiveness analyses (CEAs) comparing different modes of implant fixation in THA. Analysis of results was done with solely CEAs that had a high methodological quality. Results: A total of 12 relevant studies were identified and presented, of which 5 were considered to have the methodological rigor for inclusion in the analysis of results. These studies found that either cemented or hybrid fixation was the most cost-effective implant fixation mode for most age- and gender-specific subgroups. Conclusion: Currently available well performed CEAs generally support the use of cemented and hybrid fixation for all age-groups relevant for THA and both genders. However, these findings were mainly based on a single database and depended on assumptions made in the studies' methodology. Issues discussed in this paper have to be considered and future work is needed. [ABSTRACT FROM AUTHOR]

Abstract Background Lycopene prevents bone loss in osteopenic models. However, the role of lycopene in the success rate of dental implants under osteopenic conditions remains unknown. The aim of this study was to evaluate whether lycopene prevents delayed implant osseointegration in an ovariectomized (OVX) rat model. Methods Thirty female Sprague-Dawley rats were randomly divided into the following groups: OVX with vehicle (OVX group), OVX with lycopene (OVX + lycopene group) and sham-operated with vehicle (sham group). Twelve weeks after ovariectomy or sham operation, titanium implants were placed into the distal metaphysis of the bilateral femurs of each rat. These rats were subsequently gavaged with lycopene (50 mg/kg/day) or vehicle. After 12 weeks of gavage, all rats were sacrificed, and specimens were harvested. Sample osseointegration was evaluated by biomechanical testing, 3D micro-computed tomography (micro-CT) analysis and histomorphometric analysis. Results Compared with the OVX group, the OVX + lycopene group showed a 69.3% increase in the maximum push-out force (p 0.05). Conclusions Lycopene improved implant osseointegration, fixation and bone formation under osteopenic conditions, suggesting that lycopene is a promising therapeutic agent to prevent delayed implant osseointegration and bone loss under osteopenic conditions.

Particles released from implants cause inflammatory bone loss, which is a key factor in aseptic loosening, the most common reason for joint replacement failure. With the anticipated increased incidence of total joint replacement in the next decade, implant failure will continue to burden patients. The gut microbiome is increasingly recognized as an important factor in bone physiology, however, its role in implant loosening is currently unknown. We tested the hypothesis that implant loosening is associated with changes in the gut microbiota in a preclinical model. When the particle challenge caused local joint inflammation, decreased peri‐implant bone volume, and decreased implant fixation, the gut microbiota was affected. When the particle challenge did not cause this triad of local effects, the gut microbiota was not affected. Our results suggest that cross‐talk between these compartments is a previously unrecognized mechanism of failure following total joint replacement. [ABSTRACT FROM AUTHOR]

Radiostereometric analysis (RSA) is the most accurate method of measuring component migration using radiographs but is restricted to use in prospective studies. Ein‐Bild‐Roentgen‐analyze (EBRA)‐Cup can be used retrospectively, but its accuracy to measure component migration following revision is unknown. This study aimed to determine the accuracy of EBRA‐Cup measurements of uncemented acetabular component migration after revision total hip replacement (THR). The secondary aim was to compare the number of cases identified using EBRA‐Cup and RSA as having proximally migrated above and below 1 mm at 2 years postoperatively. EBRA‐Cup measurements were performed on plain antero‐posterior pelvic radiographs taken at the same time as RSA radiographs in a prospective cohort of 53 hips undergoing acetabular revision. At 2 years, the mean difference between the RSA and EBRA‐Cup measurements for 17 components used to treat pelvic discontinuity was 0.90 mm, significantly greater than the mean difference of 0.28 mm for 36 components without discontinuity (P =.0001). The mean difference between the RSA and EBRA‐Cup measurements at 2 years for hips that were reconstructed with an acetabular component alone, 0.28 mm, was significantly lower than hips that were reconstructed with an acetabular component in combination with an augment and/or cage, 0.74 mm (P =.0005). In conclusion, EBRA‐Cup can accurately measure migration of uncemented acetabular components used at revision THR. The presence of pelvic discontinuity, and addition of augments and cages, significantly influenced the accuracy of EBRA‐Cup measurements. EBRA‐Cup and RSA had good agreement on classification of components that migrated proximally above or below 1 mm at 2 years, with 100% sensitivity, and 87% specificity. [ABSTRACT FROM AUTHOR]

• Stress relaxation in bone led to a reduction of the cup deformations of 30% • Recording the impaction force can help to predict the fixation strength • Polyurethane foam is not suitable to replicate the viscoelasticity of bone • Initial cup deformation was similar for bone and polyurethane foam • Impulse duration decreased and impaction force increased with impact number Deformation of an acetabular cup implant during cementless implantation is indicative of the radial compressive forces, and such of the initial implant fixation strength. Stress relaxation in the surrounding bone tissue following implantation could reduce the deformation of the cup and thus primary implant fixation. The aim of this study was therefore to determine the early shape change of the implanted cup immediately after implantation with different press-fit levels and whether recording the force during cup impaction can be used to estimate initial cup fixation. Cup implantations into porcine acetabulae (n=10) were performed using a drop tower. The force induced by the drop weight and cup seating after each impact was recorded. Deformation of the implanted cup was determined with strain gauges over a period of 10min. Lever-out torques were measured to assess the initial fixation strength. Stress relaxation in the bone caused a reduction in cup deformation of 13.52±4.06% after 1min and 29.34±5.11% after 10min. The fixation strength increased with a higher force magnitude during impaction (R s 2=0.810, p=0.037). Reduction of the radial compressive forces due to stress relaxation of the surrounding bone should be considered during press-fit cup implantation in order to compensate for the reduced fixation strength over time. In addition, recording the implantation force could help to estimate initial fixation strength. [ABSTRACT FROM AUTHOR]

The fracture toughness KIc of 11 clinically used acrylic bone cements was studied in air at room temperature with single edge V‐notched beam specimens. By driving the crack step‐wise through the specimens, crack resistance curves ("R‐curves") were recorded. One group of bone cements showed an increase of the fracture toughness with increasing crack length (including CMW1+G and several Palacos bone cements) whereas another group (including Simplex, SmartSet, Copal and some Palacos bone cements) did not exhibit an R‐curve behavior. The plateau values for KIc ranged from 0.93 MPa√m (Simplex P) to 1.98 MPa√m (Palacos R+G). The observation of the crack growth with an optical microscope revealed some mechanisms influencing the crack growth like the formation of microcracks in the extended damage zone of the crack tip, the attraction of the crack by inclusions or the shielding of the crack tip by bridges in the wake of the crack. Furthermore, bone cements could be distinguished by the pattern of the path the crack followed during propagation. The crack pattern of CMW1+G provides a possible explanation of the distinct R‐curve behavior of this cement. [ABSTRACT FROM AUTHOR]

Purpose: Since the beginning of cochlear implant (CI) surgery, several techniques to fixate the electrode array at the cochleostomy and stabilize it have been described; however, most techniques use autologous tissues such as fascia, muscle, fat or fibrin glue. We describe a new surgical technique aimed to stabilize the electrode array of a CI without using autologous tissues or artificial materials. Materials and methods: The surgical technique described consists in creating three stabilizing channels in the temporal bone for the electrode array. The first one in a partially opened aditus, the second one in a partially preserved Koerner's septum (KS) and the last one in the sinodural angle. The procedure was performed in five human temporal bones using a straight array; a radiography was made to confirm the correct placement of the electrode array and afterwards all temporal bones were shaken using a Titramax 1000 platform. The correct placement of the array post-shaking was then confirmed using the microscope and another radiography. Results: No migration of the electrodes outside the cochlea was observed. The CI cable remained in the same position at the aditus and the KS in all the temporal bones. In three cases (60%), the electrode array moved away from the groove carved in the sinodural angle. Conclusions: The new surgical technique described stabilizes the electrode array using the temporal bone's normal anatomy, preserving the middle ear spaces, facilitating the ulterior explantation and reimplantation if necessary, and may reduce cost and surgery time. [ABSTRACT FROM AUTHOR]

Bioresorbable iron‐manganese alloys (Fe‐30%Mn) are considered as one of the next‐generation resorbable materials for orthopedic applications. Previous in vitro study showed that Fe30Mn scaffolds with 10% porosity displayed strong mechanical properties and adequate degradation rate without severe cytotoxicity effect. However, the cellular compatibility of these alloys in terms of cell‐to‐cell and alloy‐to‐cell interactions is not ideal. Collagen is the most abundant protein in human bone, providing structural support beneficial to bone healing. We hypothesized that coating collagen on Fe30Mn can improve osteointegration or activities promoting cell adhesion, migration, and proliferation, as the alloy degrades. After preparing collagen coating on Fe‐30Mn via spin coating, we conducted a corrosion test and a direct cytotoxicity test on four Fe30Mn groups: non‐porous and 10% porosity, with and without collagen coating. Furthermore, we evaluated and compared the morphologies of cells over a period of 7 days. Results showed that there was no significant difference between the collagen‐coated and non‐coated groups in corrosion rates, yet a significant decrease from the porous non‐coated group to the porous collagen‐coated group in cytotoxicity level was found. Cell morphology on the porous non‐coated group displayed round shape, whereas that on the porous collagen‐coated group displayed flattened spreading. The study showed that the collagen coating significantly increased the initial cell viability and adhesion for both the porous and non‐porous groups without impeding their degradation rates. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:523–535, 2020 [ABSTRACT FROM AUTHOR]

Osteoporosis poses a major public health challenge, and it is characterized by low bone mass, deterioration of the microarchitecture of bone tissue, causing a consequent increase in bone fragility and susceptibility to fractures and complicating bone fixation, particularly screw implantation. In the present study, our aim was to improve implant stability in osteoporotic bone using a thermoresponsive hyaluronan hydrogel (HA-pNIPAM) to locally deliver the bisphosphonate zoledronic acid (ZOL) to prevent bone resorption and bone morphogenetic protein 2 (BMP2) to induce bone formation. Adult female Wistar rats (n = 36) were divided into 2 treatment groups: one group of SHAM-operated animals and another group that received an ovariectomy (OVX) to induce an osteoporotic state. All animals received a polyetheretherketone (PEEK) screw in the proximal tibia. In addition, subgroups of SHAM or OVX animals received either the HA-pNIPAM hydrogel without or with ZOL/BMP2, placed into the defect site prior to screw implantation. Periprosthetic bone and implant fixation were monitored using longitudinal in vivo microCT scanning post-operatively and at 3, 6, 9, 14, 20 and 28 days. Histological assessment was performed post-mortem. Our data showed that pure hydrogel has no impact of implant fixation The ZOL/BMP2-hydrogel significantly increased bone-implant contact and peri-implant bone fraction, primarily through reduced resorption. Local delivery of ZOL and BMP2 using a biocompatible hydrogel improved implant stability in osteoporotic bone. This approach could constitute a potent alternative to systemic drug administration and may be useful in avoiding implant loosening in clinical settings. • We sought to enhance implant stability in osteoporotic rats by using a thermoresponsive hyaluronan hydrogel (HA-pNIPAM) as a local delivery system. • Pure HA-pNIPAM did not affect peri-implant bone nor contralateral bone, confirming its biocompatibility for this application. • We used a combination of zoledronic acid and bone morphogenetic protein 2 (ZOL/BMP2) to induce both an osteogenic response and prevent bone resorption. • ZOL/BMP2-releasing HA-pNIPAM enhanced implant fixation in OVX animals to levels comparable or superior to those observed in SHAM animals. [ABSTRACT FROM AUTHOR]

Fibrous dysplasia (FD) is a benign bone lesion characterized by replacement of normal bone with abnormal fibrous tissue, clinically manifesting as deformities, bone pains, and pathological fractures. The standard medical management for FD includes systemic bisphosphonate therapy. The efficacy of systemic bisphosphonate is however limited with minimal functional improvement and pain relief. Keeping the above lacunae in mind, we have made a solitary attempt at treating FD with locally administered zoledronic acid. A 25-year-old gentleman had presented to our institute with swelling and pain involving the left thigh and left lower leg. He was diagnosed as having polyostotic FD, confirmed on bone histopathology. He was administered 4 mg of zoledronic acid intravenously while 1 mg of the drug was injected locally into the femoral lesion under ultrasound and fluoroscopy guidance. There were no peri-procedural complications. At 6 months follow-up, there was marked improvement in pain scores at the left thigh, while that at the left leg remained unchanged. In addition, repeat bone scintigraphy showed a 20.8% and 25.3% reduction in anterior and posterior uptake values, respectively, at the left femur while that at the left tibia remained unaltered.

Fibrous dysplasia (FD) is a benign bone lesion characterized by replacement of normal bone with abnormal fibrous tissue, clinically manifesting as deformities, bone pains, and pathological fractures. The standard medical management for FD includes systemic bisphosphonate therapy. The efficacy of systemic bisphosphonate is however limited with minimal functional improvement and pain relief. Keeping the above lacunae in mind, we have made a solitary attempt at treating FD with locally administered zoledronic acid. A 25-year-old gentleman had presented to our institute with swelling and pain involving the left thigh and left lower leg. He was diagnosed as having polyostotic FD, confirmed on bone histopathology. He was administered 4 mg of zoledronic acid intravenously while 1 mg of the drug was injected locally into the femoral lesion under ultrasound and fluoroscopy guidance. There were no peri-procedural complications. At 6 months follow-up, there was marked improvement in pain scores at the left thigh, while that at the left leg remained unchanged. In addition, repeat bone scintigraphy showed a 20.8% and 25.3% reduction in anterior and posterior uptake values, respectively, at the left femur while that at the left tibia remained unaltered. [ABSTRACT FROM AUTHOR]

Introduction: High loosening rates after distal femoral replacement may be due to implant design not adapted to specific anatomic and biomechanical conditions.Materials and Methods: A modular tumor system (MUTARS®, Implantcast GmbH) was implanted with either a curved hexagonal or a straight tapered stems in eight Sawbones® in two consecutively generated bone defect (10 cm and 20 cm proximal to knee joint level). Implant-bone-interface micromotions were measured to analyze main fixation areas and to characterize the fixation pattern.Results: Although areas of highest relative micromotions were measured distally in all groups, areas and lengths of main fixation differed with respect to stem design and bone defect size. Regardless of these changes, overall micromotions could only be reduced with extending bone defects in case of tapered stems.Conclusions: The tapered design may be favorable in larger defects whereas the hexagonal may be advantageous in defects located more distally. [ABSTRACT FROM AUTHOR]

The effect of age on implant fixation in bone is not always considered during the design of preclinical models. The decision on animal's age is often related to practical or historical reasons, which ultimately may affect the reproducibility of results. This study aimed to quantify the effect of age by monitoring the fixation of contrast‐enhanced PEEK screws in rats, hypothesizing that the kinetics of fixation is impaired in older animals but that age effects are less severe than osteoporotic effects. The time course of implant fixation was investigated in healthy rats at 24, 40, and 60 weeks of age; and in ovariectomized rats. Implant fixation was monitored using in‐vivo microCT and dynamic histomorphometry during 1 month. The rats were euthanized 28 days post screw insertion. The data was analyzed both in absolute value and after normalization to baseline bone mass. In absolute terms, greater age had a detrimental effect on bone implant contact, bone fraction, implant stiffness, and bone remodeling but less than ovariectomy. Interestingly, once data was normalized to baseline bone mass this effect disappeared, suggesting that the physiologic response to implant placement was not affected by age. In conclusion, implant fixation kinetics is less affected by age than by baseline bone mass in this rat model. Animals of different ages can therefore be compared but data must be construed relatively to baseline bone mass and not in absolute terms. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1–12, 2018. [ABSTRACT FROM AUTHOR]

Background/Objective: The present study investigated the efficacy of poly-d,l-lactic acid (PDLLA) and hyaluronic acid (HyA) on implant fixation when coated onto hydroxyapatite/beta-tri-calcium phosphate (HA/βTCP) granules. Methods: The effect was assessed in a clinically relevant in vivo gap model in sheep. Thus, four titanium implants combined with either allograft (control), pure HA/βTCP, HyA infiltrated HA/βTCP, or PDLLA reinforced HA/βTCP granules were bilaterally inserted into the trabecular bone of the distal femurs in eight sheep. The insertion created a 2-mm peri-implant gap. After 12 weeks, histomorphometry and push-out test was used for quantification of newly formed bone in the gap, bone-implant contact, and implant fixation. Results: The histomorphometric analysis revealed the presence of newly formed bone in all groups, though substitute groups showed fragments of nonabsorbed substitute material. A significant larger bone volume was found in the allograft group versus the HA/βTCP-PDLLA group (Zone 1), and in Zone 2 a statistically significantly larger bone volume was found in the allograft compared with the HA/βTCP group. The mechanical properties and the bone-implant contact revealed no statistically significant differences between the groups. Conclusion: This study demonstrates that HA/βTCP granules coated with PDLLA and HyA have similar bone ingrowth and implant fixation as those with allograft, and with mechanical properties resembling those of allograft in advance, they may be considered as alternative substitute materials for bone formation in sheep.

Background/Objective: Despite recent progress in regeneration medicine, the repair of large bone defects due to trauma, inflammation and tumor surgery remains a major clinical challenge. This study was designed to produce large amounts of viable bone graft materials in a novel perfusion bioreactor to promote bone formation. Methods: Cylindrical defects were created bilaterally in the distal femurs of sheep, and titanium implants were inserted. The concentric gap around the implants was randomly filled either with allograft, granules, granules with bone marrow aspirate (BMA) or bioreactor activated granule (BAG). The viable BAG consisted of autologous bone marrow stromal cells (BMSCs) seeded upon porous scaffold granules incubated in a 3D perfusion bioreactor for 2 weeks prior to surgery. 6 weeks after, the bone formation and early implant fixation were assessed by means of micro-CT, histomorphometry, and mechanical test. Results: Microarchitectural analysis revealed that bone volume fraction and trabecular thickness in the allograft were not statistically different than those (combination of new bone and residue of granule) in the other 3 groups. The structure of the allograft group was typically plate-like, while the other 3 groups were combination of plate and rod. Histomorphometry showed that allograft induced significantly more bone and less fibrous tissue in the concentric gap than the other 3 granule groups, while the bone ingrowth to implant porous surface was not different. No significant differences among the groups were found regarding early implant mechanical fixation. Conclusion: In conclusion, despite nice bone formation and implant fixation in all groups, bioreactor activated graft material did not convincingly induce early implant fixation similar to allograft, and neither bioreactor nor by adding BMA credited additional benefit for bone formation in this model.

Objective: This study aims to determine the frequency of urinary tract infection (UTI), identify the isolated bacteria, and assess antibiotic sensitivity in patients undergoing orthopedic implant fixation for hip fractures., Methodology: After ethical approval from the institutional review board, this retrospective cross-sectional study was conducted at the Orthopedic Surgery Department of Dow University Hospital Karachi from June 2022 to June 2023. Through non-probability consecutive sampling, 186 patients above 16 years of age, of either gender, presenting with hip fractures such as intracapsular or extracapsular fractures, who underwent surgical fixation, were included in the study. A urine sample for urinalysis of these patients was sent on admission. Patients who presented with open fractures or those treated with conservative management were excluded from the study. The fracture diagnosis was confirmed on radiographs. All other relevant baseline investigations were also performed before surgery, per protocol, and urine-detailed and cultured reports were followed. In addition, each patient was asked about common symptoms of UTI before surgery and then diagnosed with UTI on positive urine culture and sensitivity (CS)., Results: Out of 186 hip fracture patients, 98 (52.7%) were males and 88 (47.3%) were females, with a mean age of 61.03 ± 16.43 (16-96) years. Pre-operative UTI symptoms were reported by 79 patients, including dysuria (16; 20.3%), polyuria (19; 24.0%), and burning (44; 55.7%). UTI was diagnosed on culture and sensitivity report in 65 (34.9%) patients with Escherichia coli as commonly diagnosed bacteria 35 (53.8%), followed by Enterococcus 8 (12.4%), Klebsiella 7 (10.9%), Pseudomonas aeruginosa 3 (4.7%), and Acinetobacter 2 (3.1%) patients. E. coli was sensitive to amikacin, amoxicillin/clavulanic acid, ampicillin, cefixime, ceftriaxone, cefuroxime, ciprofloxacin, colistin, cotrimoxazole, fosfomycin, gentamycin, levofloxacin, meropenem, nitrofurantoin, polymyxin B, and piperacillin-tazobactam., Conclusion: Urinary tract infection is common in patients undergoing orthopedic implant fixation for hip fractures, which can lead to potentially serious outcomes. Overall, hygiene, prompt treatment, and standard protocol should be utilized to treat those infected and minimize the spread., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Khatoon et al.)

Background Glenoid loosening, a common complication of shoulder arthroplasty, could relate to implant design and bone quality. However, the role of bone density has not been tested experimentally yet. In this study, tests on cadaveric specimens of varying bone density were performed to evaluate the effects of bone quality on loosening of typical anatomic glenoid implants. Methods Cadaveric scapulae scanned with a quantitative computed tomography scanner to determine bone mineral density (BMD) were implanted with either pegged or keeled cemented glenoid components and tested under constant glenohumeral load while a humeral head component was moved cyclically in the inferior and superior directions. Implant superior and inferior edge lifting, defined as displacement from the underlying bone, was measured with linear variable differential transducers until we reached 23,000 test cycles, and statistical testing was performed for differences in edge lifting due to implant design and related to periprosthetic BMD. Results Edge lifting was statistically significant at all time points, but on average, implant design had no effect. Lifting was highest in specimens in which BMD below the lifting edge was lower, with trends of increased displacement with decreased BMD. Conclusions Implant lifting was greater in glenoids of lower bone density for both implant designs. This finding suggests that fixation failure will most likely occur in bone of lower density and that the fixation design itself may play a secondary role. [ABSTRACT FROM AUTHOR]