Femoral Component Research Articles

Ipsilateral Femoral Neck and Shaft Fractures: Complex Injuries With High Rates of Femoral Shaft Nonunion.

To investigate nonunion rates and risk factors in patients with ipsilateral femoral neck and shaft fractures. Retrospective review. Two Level I trauma centers. Two hundred seven patients treated for ipsilateral femoral neck (AO/OTA 31-B) and shaft (AO/OTA 32A-C) fractures from 2013 to 2022. Patients with less than 6 months of follow-up were excluded. The primary outcome of this study was femoral shaft nonunion. Risk factors for nonunion were evaluated, including smoking, open fracture, delay to full weight-bearing, blood transfusions, and AO/OTA classification. Two hundred twenty-seven patients were initially identified, but only 154 patients had sufficient follow-up and were included in final analysis. The mean age was 38.9 years (SD = 15.3), and injury severity score was 19.5 (9.7). One hundred ten patients (71%) were male and 69 (45%) required intensive care unit care. Thirty-eight patients (25%) experienced an open fracture, and 44 fractures (29%) were AO/OTA Type C. Thirty patients (20%) underwent initial external fixation, and 88 patients (57%) received a perioperative transfusion. Thirty-four patients (22%) developed a femoral shaft nonunion, and 5 (3%) experienced a surgical site infection. Nonunion was associated with perioperative blood transfusion, AO/OTA Type C fracture, postoperative non-weight-bearing, and delay to full weight-bearing ≥12 weeks. Multivariable regression identified perioperative blood transfusion ≥3 (risk ratio [RR] = 1.91; CI, 1.12-2.72; P = 0.02) and AO/OTA Type C fracture (RR = 2.45; CI, 1.50-3.34; P = 0.001) as independent risk factors. Ipsilateral femoral neck and shaft fractures remain difficult injuries to treat. Much attention is given to diagnosis and treatment of the femoral neck component. These results suggest that successful treatment of the femoral shaft component presents its own challenges with high nonunion rates. Prognostic Level III.

Radiolucent lines and revision risk in total knee arthroplasty using the conventional versus the Attune S+ tibial baseplate.

This multicentre retrospective observational study's aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision. A total of 780 patients (39% male; median age 70.7 years (IQR 62.0 to 77.2)) underwent cemented TKA using the Attune Knee System) at five centres, and with the latest radiograph available for the evaluation of RLL at between six and 36 months from surgery. Univariate and multivariate logistic regression models were performed to assess associations between patient and implant-associated factors on the presence of tibial and femoral RLLs. Differences in revision risk depending on RLLs and tibial baseplate design were investigated with the log-rank test. The conventional and novel Attune baseplates were used in 349 (45%) and 431 (55%) patients, respectively. At a median follow-up of 14 months (IQR 11 to 25), RLLs were present in 29% (n = 228/777) and 15% (n = 116/776) of the tibial and femoral components, respectively, and were more common in the conventional compared to the novel baseplate. The novel baseplate was independently associated with a lower incidence of tibial and femoral RLLs (both regardless of age, sex, BMI, and time to radiograph). One- and three-year revision risk was 1% (95% CI 0.4% to 1.9%)and 6% (95% CI 2.6% to 13.2%), respectively. There was no difference between baseplate design and the presence of RLLs on the the risk of revision at short-term follow-up. The overall incidence of RLLs, as well as the incidence of tibial and femoral RLLs, was lower with the novel compared to the conventional tibial Attune baseplate design, but higher than in the predecessor design and other commonly used TKA systems.

ISTA Award 2023: Toward functional reconstruction of the pre-diseased state in total knee arthroplasty.

The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee's functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. There were evident biomechanical differences between the simulated patient models, but also trends that appeared reproducible at the population level. Optimizing the implant position significantly reduced the maximum observed strain root mean square deviations within the cohort from 36.5% to below 5.3% for all but the anterolateral ligament; and concomitantly reduced the kinematic deviations from 3.8 mm (SD 1.7) and 4.7° (SD 1.9°) with MA to 2.7 mm (SD 1.4) and 3.7° (SD 1.9°) relative to the pre-diseased state. To achieve this, the femoral component consistently required translational adjustments in the anterior, lateral, and proximal directions, while the tibial component required a more posterior slope and varus rotation in most cases. These findings confirm that MA-induced biomechanical alterations relative to the pre-diseased state can be reduced by optimizing the implant position, and may have implications to further advance pre-planning in robotic-assisted surgery in order to restore pre-diseased knee function.

A Newly Custom Coordinate System Used for Preoperative Planning of Robotic-assisted Total Knee Arthroplasty

PurposePreoperative planning is critical for total knee arthroplasty (TKA) performed with surgical robots, as it involves establishing a coordinate system to calculate the angle values of the components. This coordinate system serves as a reference during the surgical planning stage. This study aimed to develop a newly custom coordinate system suitable for integration with a surgical robot system. MethodsThe "Skywalker" surgical robot system was used to import computed tomography (CT) images of the entire lower extremities from 50 patients diagnosed with osteoarthritis. Three-dimensional reconstruction was subsequently performed. The TKA component was positioned at a fixed angle using the newly developed custom coordinate system. The angle values of the components, based on the standard CT coordinate system, were then recorded without altering their positioning. These values were analyzed to assess the differences between the two coordinate systems. ResultsThe mean and standard deviation values for the coronal, sagittal, and transverse plane positioning of the femoral component (absolute value of error) were 0.004° ± 0.020°, 0.006° ± 0.024°, and 0.158° ± 0.186°, respectively. Similarly, the mean and standard deviation values for the coronal, sagittal, and transverse plane positioning of the tibial component (absolute value of error) were 0.544° ± 0.452°, 0.042° ± 0.076°, and 0.348° ± 0.445°, respectively. ConclusionThis newly developed custom coordinate system can be employed for preoperative planning in Skywalker surgical robot system-assisted TKA, particularly for patients with significant positional abnormalities in their CT scans.

Impact of surgical alignment, bone properties, AP translation, and implant design factors on fixation in cementless unicompartmental knee arthroplasty.

Micromotion exceeding 150μm at the implant-bone interface may prevent bone formation and limit fixation after cementless knee arthroplasty. Understanding the critical parameters impacting micromotion is required for optimal implant design and clinical performance. However, few studies have focused on UKA. This study assessed the impacts of alignment, surgical, and design factors on implant-bone micromotions for a novel cementless UKA design during a series of simulated daily activities. Three validated finite element knee models for predicting cementless micromotions were loaded with design-specific kinematics/loading to simulate gait, deep knee bending, and stair descent. The implant-bone micromotion and the porous surface area ideal for bone ingrowth were estimated and compared. Overall, the peak tray-bone micromotions were consistently found at the lateral aspect of the tibial baseplate and were consistently higher than the femoral micromotions. The femoral micromotion was insensitive to almost all the factors studied, and the porous area favorable for bone ingrowth was no less than 93%. For a medial uni, implanting the tray 1mm medially or the femoral component 1mm laterally reduced the tibial micromotion by 19.3% and 26.3% respectively. A 5 mm more posterior femoral translation increased the tibial micromotion by 35.8%. The presence of the tray keel prevented the spread of the micromotion and increased the overall porous surface area. In conclusion, centralizing the load transfer to minimize tibial tray applied moment and optimizing the fixation features to minimize micromotion are consistent themes for improving cementless fixation in UKA.

Appropriate sagittal positioning of femoral components in total knee arthroplasty to prevent fracture and loosening.

This study aimed to investigate the optimal sagittal positioning of the uncemented femoral component in total knee arthroplasty to minimize the risk of aseptic loosening and periprosthetic fracture. Ten different sagittal placements of the femoral component, ranging from -5 mm (causing anterior notch) to +4 mm (causing anterior gap), were analyzed using finite element analysis. Both gait and squat loading conditions were simulated, and Von Mises stress and interface micromotion were evaluated to assess fracture and loosening risk. During gait, varied sagittal positioning did not lead to excessive Von Mises stress or micromotion. However, under squat conditions, posterior positioning (-4 and -5 mm) resulted in stress exceeding 150 MPa at the femoral notch, indicating potential fracture risk. Conversely, +1 mm and 0 mm sagittal positions demonstrated minimal interface micromotion. Slightly anterior sagittal positioning (+1 mm) or neutral positioning (0 mm) effectively reduced stress concentration at the femoral notch and minimized interface micromotion. Thus, these positions are deemed suitable to decrease the risk of aseptic loosening and periprosthetic femoral fracture.

A Systematic Review Comparing the Outcomes of Cemented Versus Uncemented Stems in Femoral Impaction Bone Grafting for Revision Hip Arthroplasty.

Femoral impaction bone grafting is a crucial technique in revision hip arthroplasty, addressing bone loss and ensuring implant stability. The choice between cemented and uncemented stems significantly influences the outcomes and long-term success of the procedure. This systematic review aims to compare the clinical outcomes of cemented versus uncemented stems in femoral impaction bone grafting. A comprehensive search of PubMed, MEDLINE Complete, and the Cochrane Library databases was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies evaluating the outcomes of femoral impaction bone grafting with cemented or uncemented stems were included. The primary outcome measured was the rate of loosening of the femoral component, while secondary outcomes included the incidence of complications such as dislocation, infection, fractures, overall patient mortality, and cardiopulmonary diseases. The literature search yielded 78 articles, with 36 meeting the inclusion criteria. These included one randomized controlled trial, 16 cohort studies (10 retrospective and six prospective), and 15 case series. Most surgeries were revision procedures, with aseptic loosening being the most common indication. For the cemented technique, 1,588 hips were analyzed, with 8.00% experiencing aseptic loosening, 3.53% dislocation, 3.87% infection, 37.33% mortality, 7.57% fractures, and 1.13% cardiopulmonary complications. For the uncemented technique, 464 hips were analyzed, with 1.72% aseptic loosening, 4.74% dislocation, 1.5% infection, 38.47% mortality, 7.76% fractures, and 0.65% cardiopulmonary complications. This systematic review highlights that both cemented and uncemented techniques for femoral impaction bone grafting offer unique benefits and challenges, with the choice depending on patient-specific factors. The uncemented technique, with a lower risk of femoral component loosening, may be better suited for younger, active patients with good bone quality, despite a slightly higher risk of fractures and dislocations. In contrast, the cemented technique, offering immediate stability, is more appropriate for elderly patients with compromised bone quality but carries a higher risk of loosening and cardiopulmonary complications. The decision should be tailored to the patient's clinical profile, including age, bone quality, comorbidities, and the surgeon's expertise.

Patient-specific instrumentation improved clinical outcome and implant survival but is not superior compared to conventional total knee arthroplasty: Ten years follow-up of a multicenter double-blind randomized controlled trial.

Patient-specific instrumentation (PSI) is a commonly used technique designed to improve mechanical alignment in total knee arthroplasty (TKA) and was therefore believed to lead to better clinical outcome and implant survival rates compared with conventional instruments (CIs). To date, long-term results comparing these two techniques are not available. This study is a 10-year follow-up of a previous double-blind multicenter randomized controlled trial where PSI was compared with CI. Patients with osteoarthritis of the knee who were candidates for TKA were included. Exclusion criteria were metal near the knee-, ankle- or hip joint, patients with contra-indications for a magnetic resonance imaging (MRI) scan and patients who had previous knee surgery (except arthroscopic meniscectomy). Clinical outcomes were assessed using patient-reported outcome measures (PROMs), and the analysis was performed with a general linear mixed model for repeated measurements. Kaplan-Meier curves were used to compare revision rates. X-rays were obtained and examined by two individual reviewers for any signs of loosening of the components. At a mean follow-up of 10.1 (SD 0.1) years, 129 patients (loss to follow-up 23%) were analysed in this trial. No statistically significant difference between the two groups were found for any of the PROMs and revision rates were comparable, six in the PSI group and three in the CI group (p = 0.29). Two X-rays in the PSI group showed a radiolucent line of the femoral component. At 10-year follow-up, PSI does not lead to better clinical outcome or survival of the prosthesis compared with CI.

Identification of Essential Features in Developing a Novel Femoral Stem Reflecting Anatomical Features of East Asian Population: A Morphological Study.

Background: Recent advancements in hip arthroplasty aim to enhance the stability, longevity, and functionality of femoral implants. However, the distal fitting of femoral stems, often caused by metaphyseal-diaphyseal mismatch, remains a significant issue, particularly in patients with Dorr type A femora. Such mismatches can result in suboptimal implant performance, leading to potential complications. This study focuses on evaluating the anatomical compatibility of five representative single-tapered wedge mid-short stems with the mediolateral (ML) anatomy of the proximal femur in an East Asian population, where these mismatches are often more pronounced. Methods: A total of 742 patients from two hospitals, all of whom underwent unilateral primary total hip arthroplasty, were included in the study. The contralateral proximal femur was confirmed to have normal anatomy in each patient. Hip anteroposterior radiographs were used for measurements, which were standardized in conjunction with CT images. Key anatomical parameters were measured, including proximal and distal medial-lateral canal dimensions, vertical offset, and medial offset. Five femoral stem designs-Tri-lock®, Taperloc®, Anthology®, Accolade II®, and Fit®-were evaluated. R programming was employed for a detailed fit analysis to match stem sizes with patient anatomy, categorizing the fit as proximal, simultaneous proximal-distal, or distal engagement. Results: Among the femoral stems analyzed, the Fit® stem demonstrated the closest alignment with the regression line for ML widths in the study population (slope = 0.69; population ML slope = 0.38). This was followed by Accolade II®, which had a slope of 0.83. In terms of offset options, the Accolade II® offered the largest offset coverage, making it particularly suitable for this population. The fit analysis revealed that the Fit® stem had the highest suitable fit rate (90.56%), followed by Accolade II® (73.04%). Taperloc®, Anthology®, and Tri-lock® had similar fit rates of approximately 59%. Overall, optimal results were obtained for 92.05% of the population in the automated fitting trial, regardless of the product type. Conclusions: When designing modern cementless femoral stems intended for press-fit fixation, it is crucial to account for the anatomical variations specific to the target population. In this study, Fit® and Accolade II® femoral components demonstrated superior compatibility with the femoral anatomy of the East Asian population, particularly in those with a higher incidence of Dorr type A femora. These stems, characterized by slimmer distal dimensions and high-offset options, appear to minimize metaphyseal-diaphyseal mismatch and associated complications.

High accuracy of component positioning and restoration of lower limb alignment using robotic medial unicompartmental knee arthroplasty.

Unicondylar arthroplasty was performed using robotic medial unicompartmental knee arthroplasty (R-mUKA) and gap-balancing instrumentation. Our hypothesis was that robotic unicondylar knee arthroplasty accurately restores component positioning and lower limb alignment when compared to preoperative planning with actual implantation throughout the range of knee motion due to proper knee balancing. Data were collected prospectively and were analysed for patients undergoing RM-UKA. A cemented UKA was implanted using the MAKO® robotic system. Lower limb alignment at 0°, 30°, 45°, 60° and 90° of flexion was recorded of the native knee, with the trial components in place and finally after component implantation. A spacer according to the femorotibial gap was introduced and the alignment was measured. The position of the final component was planned based on three-dimensional computed tomography images before making the bone cuts. The positioning of the femoral and tibial components was analysed in all three planes. A total of 52 patients were included (mean age 66.3 ± 6.7 years; 34 males, 18 females). The difference in femoral component position after planning and final implantation was 0.04° ± 0.58° more valgus in the coronal plane (p = 0.326) and 0.6° ± 1.4° more flexion relative to the sagittal plane (p = 0.034). The tibial component was placed in the coronal plane in 0.3° ± 0.8° of more varus (p = 0.113) and in the sagittal plane in 0.6° ± 1.2° of more posterior tibial slope (p = 0.001). Lower limb alignment of the native knee in extension was 5.8° ± 2.6° of varus and changed to 3° ± 2.1° varus after UKA (p ≤ 0.01). R-mUKA helps to achieve the target of alignment and component position without any significant differences to the planning. Ligament balancing causes non-significant changes in component position. It allows optimal component position even for off-the-shelf implants respecting the patient's specific anatomy. II.

Cemented Versus Cementless Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasty (UKA) offers a more conservative treatment than total knee arthroplasty when osteoarthritis affects only one tibiofemoral knee compartment. Cemented UKA has become the gold standard due to its good functional outcomes and low revision rates. The most common reasons for revision with cemented UKA include aseptic loosing, unexplained pain, and radiolucent lines. Cementless UKA, which adds a porous coating of titanium and hydroxyapatite as well as an additional peg on the femoral component, has been shown to reduce the prevalence of radiolucencies compared to cemented UKAs. National registry data have demonstrated comparable functional outcomes and improved revision rates with cementless UKA. This review aims to summarize various advancements in unicompartmental prostheses, and to highlight how the conceptual advantages of the cementless model leads to superior implant survivorship and functional outcomes.

DOES CRUCIATE LIGAMENT SUBSTITUTION AND IMPLANT ASYMMETRY MAKE A DIFFERENCE FOR TOTAL KNEE ARTHROPLASTY KINEMATICS? A MULTI-IMPLANT EVALUATION

The non-implanted knee differs in comparison to total knee arthroplasty (TKA) designs, with regard to asymmetry and functionality of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). While surgeons may choose to implant either posterior stabilized (PS) or bi-cruciate stabilized (BCS) TKAs, substituting for one or both cruciate ligaments, the effects of symmetry versus asymmetry in substituting TKA designs have not been widely analyzed to determine possible benefits. Therefore, the objective of this research study was to determine if either TKA asymmetry and/or anterior ligament stabilization can lead to more normal-like kinematics and clinical benefit for patients. In vivo, femoro-tibial kinematics for 64 subjects were evaluated in this retrospective study. Overall, ten subjects had a normal, non-implanted knee, 20 had a BCS TKA, and 34 had one of two different PS TKAs. All three TKAs had varying degrees of symmetry incorporated into the design, and all were implanted by the same surgeon and were analyzed using fluoroscopy during a deep knee bend. At full extension, the BCS TKA subjects demonstrated a statistically more anterior position of both condyles compared to both PS TKAs. The BCS TKA subjects also experienced more posterior femoral rollback and axial rotation in early flexion and from full extension to maximum knee flexion. Additionally, the TKAs in this study having asymmetry experienced greater amounts of posterior femoral rollback and weight-bearing knee flexion. The results from this study indicated that in early flexion, the anterior cam/post mechanism does pull the femoral component more anterior, and all TKAs experienced posterior femoral rollback when the posterior cam engaged the post. The asymmetric designs also achieved greater rollback and axial rotation compared to the symmetric designs.

Development of functionally graded structure for hip endoprosthesis stem based on lattice-type metamaterial

The paper reports on design and studies of a promising configuration of a hip endoprosthesis stem. The femoral component of the endoprosthesis is constructed based on a metamaterial produced by additive technologies, representing a periodic porous structure of variable topology. The central goal of the design procedure was to numerically determine the spatially graded relative density of the lattice structure within the implant volume by solving the optimization problem. The first stage of development comprised finite element modeling of a system with a solid implant attached, i.e., the optimization space, for seven different loading scenarios. These scenarios were constructed to represent the most typical cases of human motor activity. The second step was to determine the optimal spatial distribution of relative density of the lattice structure in the implant volume, obtained by solving the topological optimization problem under the given loading. After the optimization problem was solved, the distribution of the relative density of the lattice structure was obtained, serving as a basis for constructing a geometric model of a functionally graded porous scaffold for implantation. This result allows achieving an optimal ratio of stiffness and mass properties under the given loading conditions. The approach was verified by direct finite element modeling of the constructed lattice geometry of the implant under specific loading scenarios. Analyzing the stress fields in the volume of the endoprosthesis, we concluded that there were no critical regions in the developed structure, so the approach taken to develop the metamaterial-based endoprosthesis can be deemed correct.

CT Morphometric Analysis of the Medial Femoral Condyle in an Indian Population: A Comparative Study of Unicompartmental Knee Arthroplasty Implants.

Purpose The objective of this study was to evaluate the compatibility of the medial femoral condyle (MFC) dimensions in the Indian population with the standard femoral components of three commercially available unicompartmental knee arthroplasty (UKA) implants. Methods This analytical study utilized CTmorphometric data from 100 consecutive non-arthritic adult knees. MFC dimensions were measured to assess their compatibility with UKA prostheses. The proportion of knees that could be optimally replaced using three commercially available UKA femoral implant systems, Link, DePuy, and Smith & Nephew, was calculated. Results The study cohort comprised 56 males and 44 females, with a mean age of 43.28 ± 10.53 years. For the Link implant system, the 'small' size was the most compatible, fitting 43% (43) of the patients, followed by 'medium-small' (35%, n = 35) and 'medium' (16%, n = 16). For the DePuy Sigma Uni implant, the best fit was 'size 1' for 38% (38) of the patients, followed by 'size 3' (25%, n = 25), 'size 4' (13%, n = 13), 'size 2' (10%, n = 10), and 'size 5' (2%, n = 2). In the case of the Smith & Nephew system, 'size 2' was the best fit for 30% (30) of the knees, followed by 'size 3' (27%, n = 27), 'size 4' (15%, n = 15), 'size 1' (12%, n = 12), and 'size 5' (8%, n = 8). Overhang of the femoral component, due to the MFC being smaller than the smallest available femoral component size, was observed in 6% (6) of knees with Link implants, 12% (12) with DePuy implants, and 8% (8) with Smith & Nephew implants. Conclusion The findings indicate that the most suitable femoral component sizes for Indian knees were 'small' in the Link system (43%, n = 43), 'size 1' in the DePuy system (38%, n = 38), and 'size 2' in the Smith & Nephew system (30%, n = 30). The results suggest a need for implant manufacturers to consider developing customized components tailored to the Indian population to enhance fit and minimize the occurrence of femoral component overhang.

Does the femoral component design modified in consideration of Asian anatomical characteristics fit better than the conventional design for Korean femora in reality?

We aimed to investigate the anatomical and clinical advantages of an Asian-specific femoral component design with a high femoral aspect ratio, compared with the conventional femoral component design. A retrospective analysis of the operation and outpatient clinic records of 239 knees operated on using an anatomically modified femoral component design (MFCD, Group A) and 153 knees operated on using a conventional femoral component design (CFCD, Group B) in Korean patients was performed. Three subgroups were created based on the mediolateral size of the two different femoral component designs. The geometric accommodation of each femoral component was assessed using intraoperatively measured femoral posterior condylar resection and posterior condylar trimming amounts. Clinical outcomes were assessed using a range of motion (ROM) and patient-reported outcome measurements. In the comparison between Groups A and B, the mean combined bilateral posterior condylar trimming (XPCT) was 2.91 [2SD: -4.12-9.94] and 1.45 [2SD: -5.89-8.80], and the median XPCT was 3 and 1.5. In the largest subgroup (subgroup 2), Groups A and B included 100 and 112 patients, all six posterior condylar resection and trimming parameters were significantly larger in Group A. Preoperative and postoperative ROM and Hospital for Special Surgery scores were similar between the two groups. Preoperative Western Ontario and McMaster Universities Arthritis Index (WOMAC) was higher in Group A. However, postoperative WOMAC was similar between the groups. Perioperative improvement in WOMAC index was significantly greater in Group B. The Asian-specific femoral component design resulted in more resection and trimming of the femoral posterior condyle than the conventional design despite it was not associated with different clinical outcomes. Surgeons should be aware of unexpected excessive posterior condylar resection and formation of large flexion gap when using femoral component design with high femoral aspect ratio.

Effect of tibia-first, restricted functional alignment technique on gap width changes, and component positioning in robotic arm-assisted total knee arthroplasty.

This study aims to quantitatively assess the predictability of post-resection gap dimensions and the attainment of balanced gaps using robotic arm-assisted total knee arthroplasty (TKA). This retrospective cohort study included 100 consecutive patients who underwent robotic arm-assisted TKA for knee osteoarthritis using a restricted functional alignment (FA) technique. Tibial cuts were performed based on preoperative tibial anatomy within predefined boundaries, followed by femoral component adjustments according to tensioned soft tissues to optimise gap balance. The primary outcome was the proportion of balanced gaps, defined as differential laxities of ≤2 mm, across extension, flexion, lateral, and medial gap measurements. Ligament balancing in lateral and medial compartments was assessed using a robotic system at 10° and 90° flexion to evaluate if restricted FA facilitated a balanced knee. Secondary outcomes included implant alignment, resection depth, and patient-reported outcome measures (PROMs). Significant increases in both lateral and medial gaps at 10° and 90° flexion were observed following tibial and femoral bone resections (p < 0.001). At extension, average gap changes were 0.9 mm (lateral) and 1.6 mm (medial) after tibial cuts, and 0.5 mm (lateral) and 1.2 mm (medial) after femoral cuts. At 90° flexion, changes were 0.3 mm (lateral) and 1.7 mm (medial) following tibial cuts, and 1.0 mm (lateral) and 1.4 mm (medial) after femoral cuts. Despite these variations, the tibia-first, gap-balancing technique achieved overall balance in 98% of gap measurements. The tibial component was placed at an average of 2.1° varus, while the femoral component was positioned at 0.3° varus and 1.3° external rotation relative to the surgical transepicondylar axis. Significant improvements in PROMs were noted between preoperative and one-year postoperative evaluations (all p < 0.05). The tibia-first, restricted FA technique achieved a well-balanced knee in 98% of cases, despite inconsistent gap increments observed between initial assessments and post-resection. Therapeutic Level IV.

A retrospective study on two different surgical robots to assist total knee arthroplasty

To compare early clinical and imaging results of domestic HURWA and imported Brainlab Knee3 surgical robot-assisted knee replacement. A retrospective analysis was performed on 93 patients with knee osteoarthritis (KOA) who underwent robot-assisted descending total knee arthroplasty(TKA) from January 2021 to July 2023, and they were divided into BRATKA group and HRATKA group according to use of robotic system. There were 40 patients in BRATKA group, including 16 males and 24 females, aged from 55 to 90 years old with an average of (64.3±7.0) years old;27 patients with grade Ⅲ and 13 patients with grade Ⅳ according to Kellgren-Lawrence(K-L);18 patients on the right side and 22 patients on the left side;the courses of disease ranged from 1 to 30 years with an average of (15.3±7.6) years;imported Brainlab Knee3 surgical robot assisted system was adopted. There were 53 patients in HRATKA group, including 18 males and 35 females, aged from 52 to 81 years old with an average of (64.4±8.5) years old;30 patients with grade Ⅲ and 23 patients with grade Ⅳ;21 patients on the right side and 32 patients on the left side;the courses of disease ranged from 1 to 32 years with an average of (16.4±7.9) years;HURWA surgical robot assisted system was adopted. Operation time, perioperative total blood loss, incision length and postoperative complications were compared between two groups. Deviation angle of hip-knee-ankle angle(HKAA) before operation and on the first day after operation was compared between two groups. Later tibal component (LTC), frontal femoral component (FFC), later femoral component (LFC) and frontal tibal component(FTC) at 1 day after on the first day after operation was compared between two groups. Knee Society score(KSS), visual analogue scale (VAS) and range of motion (ROM) of knee joint were compared between two groups before operation and on the 3rd and 90th day after operation. Both groups were followed up for 11 to 18 months with an average of (14.4±2.1) months, and the wounds of all patients healed well. Operation time and incision length of BRATKA group were (132.1±34.6) min and (12.9±1.9) cm, while (94.1±10.8) min and (14.8±2.1) cm in HRATKA group, respectively, and the differences between two groups were statistically significant(P<0.05). There were no significant difference in perioperative total blood loss and preoperative deviation angle of HKAA between two groups(P>0.05). Deviation angle of HKAA, FFC angle and LFC angle in BRATKA group were (1.90±0.91) °, (87.90±1.51) ° and(9.00±3.2) °, respectively;while (0.93±1.04) °, (89.03±0.96) ° and (7.63±0.59) ° in HRATKA group, respectively, and the differences between two groups were statistically significant (P<0.05). There were no significant differences in FTC and LTC between two groups(P>0.05). There were no significant differences in VAS of knee rest and exercise, KSS score and ROM of knee joint between two groups before operation and 3 days and 90 days after operation(P>0.05). There was no significant difference in complications between two groups (P>0.05). Postoperative imaging of two robot systems showed good lower limb force line. The domestic HRATKA group had better LFC, FFC angle and HKA deviation angle than the imported BRATKA group, but there were no significant difference in postoperative knee function and pain relief.

The role of MRI in the diagnosis of aseptic loosening following total hip arthroplasty.

The role of advanced imaging in diagnosing aseptic implant loosening following total hip arthroplasty (THA) remains unclear. This study aimed to assess the diagnostic value of magnetic resonance imaging (MRI) in detecting aseptic loosening. This was a retrospective review of 342 consecutive patients who underwent revision THA between July 2011 and April 2023 and had a pelvis MRI as part of the preoperative diagnostic evaluation. Among them, 62 patients had an intraoperative diagnosis of aseptic loosening of either the femoral or acetabular component. Patients were stratified based on the concordance between their MRI and radiographs findings. Preoperative MRI showed signs of aseptic loosening in 25/62 patients (sensitivity = 40.3%). Similarly, preoperative radiographs demonstrated signs of aseptic loosening in 27 patients (43.5%). Twelve patients (19.4%) had both MRI and radiographs predictive of aseptic loosening, 22 patients (35.5%) did not show signs of aseptic loosening in either MRI or radiographs, and for 28 patients (45.2%), the results were discordant. Among the patients with a negative radiograph for aseptic loosening (n = 35), 13 patients (37.1%) showed signs of aseptic loosening on MRI. Aseptic loosening remains an elusive diagnosis, and the findings of this study suggest that the utility of MRI and radiographs as part of the diagnostic process is limited. However, in cases of presumed aseptic loosening with inconclusive radiographs findings, MRI may play a role in improving the diagnostic process. III.

Long-term clinical results and patient satisfaction of a metaphyseal-engaging anatomic cementless femoral component in total hip arthroplasty.

There is relatively little information on the long-term clinical results of patients aged < 50 years with a contemporary total hip arthroplasty (THA), although a high rate of revision is projected for this group. Therefore, the purpose of this study was to evaluate the long-term results (a minimum of 21 years) of a metaphyseal-engaging anatomic cementless total hip prosthesis in patients aged < 50 years at the time of their THA. This study included 360 patients (498 hips), specifically 212 men and 148 women. The mean age of the patients at the time of their THA was 45.8 ± 8.1 years. The predominant diagnosis was osteonecrosis (56%). Demographic data, the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the University of California, Los Angeles (UCLA) activity score were recorded. Radiographic evaluation and dual-energy X-ray absorptiometry (DEXA) scanning were used to evaluate implant fixation, bone remodelling, and osteolysis. The mean follow-up was 25.2 year (range 21-28 years). At the latest follow-up, the mean Harris hip, WOMAC, and UCLA activity scores were 93, 10, and 6.7 points, respectively. No patients had thigh pain. All hips had osseous integration of the acetabular and femoral components. No patient had grade 3 stress shielding. The 28-year survival rate was 98.2% (95% confidence interval [CI] 95-100%) for the acetabular components and 98.8% (95% CI 95-100%) for the femoral components. Overall, 90% of the patients were satisfied with the THA results. The results suggest that a metaphyseal-engaging anatomic cementless femoral stem with alumina-on-alumina ceramic articulation provide outstanding long-term fixation and substantial pain relief well into the 3rd decade after surgery. Furthermore, there was no alumina ceramic fracture or osteolysis. Moreover, approximately 90% of the patients were satisfied with the results of their THA.

Does patient-specific instrument or robot improve imaging and functional outcomes in unicompartmental knee arthroplasty? A bayesian analysis.

This study conducted a Bayesian network meta-analysis (NMA) to compare the imaging and functional outcomes of patient-specific instrument-assisted unicompartmental knee arthroplasty (P-UKA), robot-assisted unicompartmental knee arthroplasty (R-UKA), and conventional unicompartmental knee arthroplasty (C-UKA). A comprehensive search was performed on five electronic databases and major orthopedic journals as of September 24, 2023. We included randomized controlled studies featuring at least two interventions of P-UKA, R-UKA, or C-UKA. Primary outcomes encompassed the deviation angle of hip-knee-ankle angle, as well as the coronal and sagittal plane alignment of femoral and tibial components. Secondary outcomes included patient-reported outcome measures (PROM), surgery time, revision rate, and complication rate. Bayesian framework was employed for risk ratio (RR) or mean deviation (MD) analysis, and treatment hierarchy was established based on rank probabilities. This NMA included 871 knees from 12 selected studies. In sagittal plane, R-UKA exhibited a significantly reduced deviation angle of femoral component compared to P-UKA (MD: 4.16, 95% CI: 0.21, 8.07), and of tibial component in comparison to C-UKA (MD: -2.45, 95% CI: -4.20, -0.68). Notably, the surgery time was significantly longer in R-UKA than in C-UKA (MD: 15.98, 95% CI: 3.11, 28.88). However, no significant differences were observed in other outcomes. Compared with P-UKA or C-UKA, R-UKA significantly improves the femoral and tibial component alignment in the sagittal plane, although this does not translate into discernible differences in functional outcomes. Comprehensive considerations of economic and learning costs are imperative for the judicious selection of the appropriate procedure.