Design and In Vitro Validation of an Orthopaedic Drill Guide for Femoral Stem Revision in Total Hip Arthroplasty.

OBJECTIVE: Cemented total hip arthroplasty (THA) demonstrates superior survival rates compared to uncemented procedures. Nevertheless, most younger patients opt for uncemented THA, as removing well-fixed bone cement in the femur during revisions is complex, particularly the distal cement plug. This removal procedure often increases the risk of femoral fracture or perforation, haemorrhage and weakening bone due to poor drill control and positioning. Aim of this study was to design a novel drill guide to improve drill positioning. METHODS AND PROCEDURES: A novel orthopaedic drill guide was developed, featuring a compliant centralizer activated by a drill guide actuator. Bone models were prepared to assess centralizing performance. Three conditions were tested: drilling without guidance, guided drilling with centralizer activation held, and guided drilling with centralizer activation released. Deviations from the bone centre were measured at the entry and exit point of the drill. RESULTS: In the centralizing performance test, the drill guide significantly reduced drill hole deviations in both entry and exit points compared to the control ([Formula: see text]). The absolute deviation on the exit side of the cement plug was 10.59mm (SD 1.56) for the 'No drill guide' condition, 3.02mm (SD 2.09) for 'Drill guide - hold' and 2.12mm (SD 1.71) for 'Drill guide - release'. The compliant drill guide centralizer significantly lowered the risk of cortical bone perforation during intramedullary canal drilling in the bone models due to better control of the cement drill position. Clinical and Translational Impact Statement: The drill guide potentially reduces perioperative risks in cemented femoral stem revision. Future research should identify optimal scenarios for its application.

Towards an optimal design of a functionally graded porous uncemented acetabular component using genetic algorithm.

Generation of polyethylene wear debris and peri­prosthetic bone resorption have been identified as potential causes of acetabular component loosening in Total Hip Arthroplasty. This study was aimed at optimization of a functionally graded porous acetabular component to minimize peri­prosthetic bone resorption and polyethylene liner wear. Porosity levels (porosity values at acetabular rim, and dome) and functional gradation exponents (radial and polar) were considered as the design parameters. The relationship between porosity and elastic properties were obtained from numerical homogenization. The multi-objective optimization was carried out using a non-dominated sorting genetic algorithm integrated with finite element analysis of the hemipelvises subject to various loading conditions of common daily activities. The optimal functionally graded porous designs (OFGPs -1, -2, -3, -4, -5) exhibited less strain-shielding in cancellous bone compared to solid metal-backing. Maximum bone-implant interfacial micromotions (63-68 µm) for OFGPs were found to be close to that of solid metal-backing (66 µm), which might facilitate bone ingrowth. However, OFGPs exhibited an increase in volumetric wear (3-10 %) compared to solid metal-backing. The objective functions were found to be more sensitive to changes in polar gradation exponent than radial gradation exponent, based on the Sobol' method. Considering the common failure mechanisms, OFGP-1, having highly porous acetabular rim and less porous dome, appears to be a better alternative to the solid metal-backing.

Investigation of stair ascending and descending activities on the lifespan of hip implants.

Total hip arthroplasty (THA) surgeries among young patients are on the increase, so it is crucial to predict the lifespan of hip implants correctly and produce solutions to improve longevity. Current implants are designed and tested against walking conditions to predict the wear rates. However, it would be reasonable to include the additional effects of other daily life activities on wear rates to predict convergent results to clinical outputs. In this study, 14 participants are recruited to perform stair ascending (AS), descending (DS), and walking activities to obtain kinematic and kinetic data for each cycle using marker based Qualisys motion capture (MOCAP) system. AnyBody Modeling System using the Calibrated Anatomical System Technique (CAST) full body marker set are performed Multibody simulations. The 3D generic musculoskeletal model used in this study is a marker-based full-body motion capture model (AMMR,2.3.1 MoCapModel) consisting of the upper extremity and the Twente Lower Extremity Model (TLEM2). The dynamic wear prediction model detailing the intermittent and overall wear rates for CoCr-on-XLPE bearing couple is developed to investigate the wear mechanism under 3D loading for AS, DS, and walking activities over 5 million cycles (Mc) by using finite element modelling technique. The volumetric wear rates of XLPE liner under AS, DS, and walking activities over 5-Mc are predicted as 27.43, 23.22, and 18.84 mm3/Mc respectively. Additionally, the wear rate was predicted by combining stair activities and gait cycles based on the walk-to-stair ratio. By adding the effect of stair activities, the volumetric wear rate of XLPE is predicted as 22.02 mm3/Mc which is equivalent to 19.41% of walking. In conclusion, in this study, the effect of including other daily life activities is demonstrated and evidence is provided by matching them to the clinical data as opposed to simulator test results of implants under ISO 14242 boundary conditions.

Mid-term results of cemented hip arthroplasties through the direct anterior approach in the lateral decubitus position: a retrospective cohort study.

BACKGROUND: Reports show a high complication rate when starting with the Direct Anterior Approach (DAA) in a supine position for hip arthroplasty. The DAA with the patient in lateral decubitus position may avoid this problem because it supposedly provides better visibility, especially on the femoral side. However, this approach did show a rather high complication rate during the adoption of the approach at 1 year follow up in our previous report. We were interested what the overall 7 year survival estimate would be and whether improvement could be seen with growing experience. METHODS: A cohort of patients undergoing total hip arthroplasty right from the start of applying the DAA in lateral decubitus position was analysed. RESULTS: In total 175 hip prostheses (162 patients) were evaluated. The 7-year survival estimate was 95.1%, 95 CI: 91.8-98.4%. In 6 of 8 revisions there was aseptic loosening of the stem. By dividing the cohort into 3 consecutive groups in time we did not see a significantly improving revision rate. CONCLUSIONS: In our experience, the adoption of the direct anterior approach in lateral decubitus position caused a relatively low 7-year survival estimate without an apparent decrease with growing experience, however given the low number of cases further research is needed to investigate the long-term risk of adopting a new approach.

Mid-term results of titanium-titanium modular neck femoral stem in primary total hip arthroplasty.

BACKGROUND: Modular neck femoral stems are advantageous because they can accurately restore the ideal hip geometry using various options in terms of offset, length, and version. However, there are concerns regarding junctional problems. Despite several reports on such issues, there is a lack of study on mid- to long-term results of these stems. The current study evaluated the mid-term results of patients who underwent primary total hip arthroplasty using a titanium-titanium (Ti-Ti) modular neck femoral stem. METHODS: In total, data on 47 hips (42 patients) that could be followed-up for ≥ 5 years after primary total hip arthroplasty using the Ti-Ti modular neck femoral stem from 2011 to 2015 were reviewed. There were 22 male and 20 female patients, and their mean age was 56.3 (range: 31-76) years. The mean follow-up period was 8 (range: 5-12) years. Functional and radiological outcomes, complications, and reoperations were investigated. In addition, we conducted a comparative analysis of the outcomes between those who underwent surgery using the Ti-Ti modular neck femoral stem and 41 hips (35 patients, 19 males and 16 females) that underwent primary total hip arthroplasty using nonmodular femoral stems as a control. RESULTS: In all Ti-Ti cases, the mean Harris Hip Scores were 50.6 (range: 6-59) preoperatively and 92.7 (range: 78-99) at the last follow-up (P < 0.001). Regarding the neck component's modularity, straight neck components were used in all Ti-Ti cases, and an anteverted or a retroverted neck was not used in any case. Stem revision was performed in one hip due to aseptic loosening. One hip underwent open reduction and internal fixation due to periprosthetic fracture without stem loosening. There were no cases of osteolysis and periprosthetic joint infection and clinically detectable junctional problems. The stem survival rate, with any stem revision as the endpoint, at 12 years was 96.6%. No significant difference was observed in the functional and radiological outcomes beween the Ti-Ti and nonmodular groups. CONCLUSIONS: The Ti-Ti modular neck femoral stem had comparable results with broadly used nonmodular femoral stems; hence, it can be a reliable option in primary total hip arthroplasty. However, in terms of the modularity itself of the modular neck femoral stem, whether the modular neck femoral stem is useful in uncomplicated primary total hip arthroplasty is unclear.

Comparison between accuracy of augmented reality computed tomography-based and portable augmented reality-based navigation systems for cup insertion in total hip arthroplasty.

Augmented reality (AR) has been used for navigation during total hip arthroplasty (THA). AR computed tomography (CT)-based navigation systems and AR-based portable navigation systems that use smartphones can also be used. This study compared the accuracy of cup insertion during THA using AR-CT-based and portable AR-based navigation systems. Patients with symptomatic hip disease who underwent primary THA in the supine position using both AR CT-based and portable AR-based navigation systems simultaneously between October 2021 and July 2023 were included. The primary outcome of this study was the absolute difference between cup angles in the intraoperative navigation record and those measured on postoperative CT. The secondary outcome was to determine the factors affecting the absolute value of the navigation error in radiographic inclination (RI) and radiographic anteversion (RA) of the cup, including sex, age, body mass index, left or right side, approach, and preoperative pelvic tilt. This study included 94 consecutive patients. There were 11 men and 83 women, with a mean age of 68 years. The mean absolute errors of RI were 2.7° ± 2.0° in the AR CT-based and 3.3° ± 2.4° in the portable AR-based navigation system. The mean absolute errors of RA were 2.5° ± 2.1° in the AR CT-based navigation system and 2.3° ± 2.2° in the portable AR-based navigation system. No significant differences were observed in RI or RA of the cup between the two navigation systems (RI: p = 0.706; RA: p = 0.329). No significant factors affected the absolute value of the navigation errors in RI and RA. In conclusion, there were no differences in the accuracy of cup insertion between the AR CT-based and portable AR-based navigation systems.

Cierre de herida en cirugía protésica de rodilla y cadera (PTR y PTC): Resultados de una encuesta sobre la práctica clínica en España / Wound closure after knee and hip replacement (TKA and THA): Survey results on the clinical practice in Spain

Introducción y objetivos: En cirugía protésica de rodilla y cadera está claro que aún no se ha desarrollado una técnica de cierre estandarizada óptima. A nivel local no existen datos que describan la práctica quirúrgica habitual en cierre de herida. El objetivo de este trabajo es analizar el cierre de herida en cirugía protésica a través de una encuesta sobre una muestra representativa a nivel nacional y así obtener información sobre el contexto del cierre en España. Material y método: Se conforma un grupo ad hoc de especialistas en cirugía protésica. El grupo de expertos, posterior al análisis de la literatura, elabora un cuestionario de 32 preguntas cerradas de opción múltiple, divididas en los siguientes bloques: hemostasia, cierre quirúrgico de la herida y apósitos. Resultados: Un total de 471 cirujanos respondieron la encuesta de forma completa y con información suficiente para efectuar el análisis descriptivo; 79% cree que el ácido tranexámico (ATX) puede influir en la disminución de tasa de infección de sitio quirúrgico; 96% cree que el tipo de cierre profundo a nivel de la artrotomía podría influir en los resultados y complicaciones tras prótesis de cadera y/o rodilla; 85% cree que el tipo de cierre superficial a nivel subcutáneo puede influir en los resultados y complicaciones tras prótesis de cadera y/o rodilla; 64% de los cirujanos utiliza la terapia de presión negativa incisional de simple uso para el tratamiento de las complicaciones de la herida quirúrgica (seromas, drenaje prolongado, dehiscencias). Conclusiones: Existe en nuestro entorno una alta variabilidad en el cierre de la herida y una baja inversión en formación sobre este tema. Los autores recomiendan a las diferentes sociedades científicas la inversión de recursos para mejorar la formación en dicho campo y reducir el porcentaje de cirujanos que se consideran inadecuadamente formados, así como adaptar las técnicas de cierre a aquellas consideradas patrón oro según la evidencia.(AU)

Background and objective: In orthopedic surgery, it is clear that an optimal standardized closure technique has not yet been developed. Locally, there are no objective data describing the standard surgical practice in wound closure. The aim of this study is to analyze the clinical practice of surgical wound closure in orthopedic surgery by means of a survey of a representative local sample and thus obtain information on the context of closure in Spain. Method: an ad hoc group of specialists in orthopedic surgery and traumatology was formed. The group of experts, after analyzing the literature, developed a questionnaire of 32 closed multiple-choice questions divided into the following blocks: hemostasis, surgical wound closure (deep, superficial, and cutaneous), and dressings. Results: A total of 471 surgeons responded to the survey completely and with sufficient information to perform the descriptive analysis. 79% believe that ATX can influence the decrease in surgical site infection rate. 96% believe that the type of deep closure at the level of the arthrotomy could influence outcomes and complications after hip and/or knee replacements. 85% believe that the type of shallow closure at the subcutaneous level may influence outcomes and complications after hip and/or knee replacement. 64% of surgeons use single-use incisional negative pressure therapy for the treatment of surgical wound complications (seroma, prolonged drainage, dehiscence). Conclusions: There is a high level of variability in wound closure in our setting and a low level of training on the subject. The authors recommend that the different scientific societies invest resources to improve training in this field and reduce the percentage of surgeons who are considered inadequately trained, as well as adapting closure techniques to those considered gold standard according to the evidence.(AU)

[Translated article] Wound closure after knee and hip replacement (TKA and THA): Survey results on the clinical practice in Spain / Cierre de herida en cirugía protésica de rodilla y cadera (PTR y PTC): resultados de una encuesta sobre la práctica clínica en España

Introducción y objetivos: En cirugía protésica de rodilla y cadera está claro que aún no se ha desarrollado una técnica de cierre estandarizada óptima. A nivel local no existen datos que describan la práctica quirúrgica habitual en cierre de herida. El objetivo de este trabajo es analizar el cierre de herida en cirugía protésica a través de una encuesta sobre una muestra representativa a nivel nacional y así obtener información sobre el contexto del cierre en España. Material y método: Se conforma un grupo ad hoc de especialistas en cirugía protésica. El grupo de expertos, posterior al análisis de la literatura, elabora un cuestionario de 32 preguntas cerradas de opción múltiple, divididas en los siguientes bloques: hemostasia, cierre quirúrgico de la herida y apósitos. Resultados: Un total de 471 cirujanos respondieron la encuesta de forma completa y con información suficiente para efectuar el análisis descriptivo; 79% cree que el ácido tranexámico (ATX) puede influir en la disminución de tasa de infección de sitio quirúrgico; 96% cree que el tipo de cierre profundo a nivel de la artrotomía podría influir en los resultados y complicaciones tras prótesis de cadera y/o rodilla; 85% cree que el tipo de cierre superficial a nivel subcutáneo puede influir en los resultados y complicaciones tras prótesis de cadera y/o rodilla; 64% de los cirujanos utiliza la terapia de presión negativa incisional de simple uso para el tratamiento de las complicaciones de la herida quirúrgica (seromas, drenaje prolongado, dehiscencias). Conclusiones: Existe en nuestro entorno una alta variabilidad en el cierre de la herida y una baja inversión en formación sobre este tema. Los autores recomiendan a las diferentes sociedades científicas la inversión de recursos para mejorar la formación en dicho campo y reducir el porcentaje de cirujanos que se consideran inadecuadamente formados, así como adaptar las técnicas de cierre a aquellas consideradas patrón oro según la evidencia.(AU)

Background and objective: In orthopedic surgery, it is clear that an optimal standardized closure technique has not yet been developed. Locally, there are no objective data describing the standard surgical practice in wound closure. The aim of this study is to analyze the clinical practice of surgical wound closure in orthopedic surgery by means of a survey of a representative local sample and thus obtain information on the context of closure in Spain. Method: an ad hoc group of specialists in orthopedic surgery and traumatology was formed. The group of experts, after analyzing the literature, developed a questionnaire of 32 closed multiple-choice questions divided into the following blocks: hemostasis, surgical wound closure (deep, superficial, and cutaneous), and dressings. Results: A total of 471 surgeons responded to the survey completely and with sufficient information to perform the descriptive analysis. 79% believe that ATX can influence the decrease in surgical site infection rate. 96% believe that the type of deep closure at the level of the arthrotomy could influence outcomes and complications after hip and/or knee replacements. 85% believe that the type of shallow closure at the subcutaneous level may influence outcomes and complications after hip and/or knee replacement. 64% of surgeons use single-use incisional negative pressure therapy for the treatment of surgical wound complications (seroma, prolonged drainage, dehiscence). Conclusions: There is a high level of variability in wound closure in our setting and a low level of training on the subject. The authors recommend that the different scientific societies invest resources to improve training in this field and reduce the percentage of surgeons who are considered inadequately trained, as well as adapting closure techniques to those considered gold standard according to the evidence.(AU)

Validación de la versión española de la escala de Harris modificada / Validation of the Spanish version of the modified Harris score

Antecedentes y objetivos: La escala de Harris modificada (EHM) es una de las herramientas más utilizadas para valorar pacientes con patología de cadera. A pesar de contar con una adaptación transcultural al español realizada por Lara et al., no cuenta con estudios que sustenten su validez. Se pretende obtener una validación de la versión adaptada de la EHM (ES-EHM), comparándola con la escala WOMAC. Materiales y métodos: La ES-EHM se aplicó a 100 pacientes operados de prótesis total de cadera: (1) previamente a la cirugía (ES-EHM prequirúrgica), (2) 2 años tras la cirugía (ES-EHM posquirúrgica) y (3) 6 meses después de la aplicación de la ES-EHM posquirúrgica (ES-EHM final). Se aplicó también, en una ocasión, el cuestionario WOMAC. Se compararon las medias de la ES-EHM prequirúrgica, posquirúrgica y final, así como la totalidad y los parámetros de dolor y función de la ES-EHM con la escala WOMAC. Se obtuvieron parámetros de fiabilidad, validez y sensibilidad al cambio. Resultados: Al comparar la ES-EHM prequirúrgica y la posquirúrgica, se observó una mejoría clínicamente relevante (46,54 puntos). Al comparar la ES-EHM posquirúrgica y la final, no se detectaron diferencias. Se obtuvo una correlación fuerte entre: (1) la ES-EHM posquirúrgica y la ES-EHM final, (2) ES-EHM y WOMAC y (3) parámetros de dolor y función de la ES-EHM y la WOMAC. El índice de respuesta media estandarizada fue de 2,99, la fiabilidad test-retest representada por el coeficiente de correlación intraclase de 0,90 y el índice de consistencia interna alfa de Cronbach de 0,95. Conclusiones: La adaptación transcultural de la ES-EHM muestra ser fiable, válida y sensible al cambio. Por lo tanto, el personal médico de la población española podrá aplicar la ES-EHM con el respaldo científico y la certeza de estar midiendo los parámetros deseados.(AU)

Background and objectives: Modified Harris Hip Score (HHS) is one of the most used scales in the assessment of patients with hip pathology. Although a Spanish cross-cultural adaptation has been recently published, there are many studies supporting its validity yet. Therefore, the aim of this study is to validate the newly adapted Spanish version of the HHS (ES-EHM), comparing it with the WOMAC scale. Materials and methods: The ES-EHM scale was applied to 100 patients who underwent a total hip replacement, in three different situations: (1) prior to surgery (pre-surgical ES-EHM), (2) after surgery, with at least 2 years of follow up (after surgery ES-EHM), and (3) 6 months after the postsurgical registration (final ES-EHM). WOMAC questionnaire was also applied once. We analyzed data of scale main score, pain score, function-related score as well as the mean of pre-surgical, postsurgical and final postsurgical ES-EHM scale, in both the ES-EHM and the WOMAC scales. Parameters of reliability, validity and sensitivity to change were obtained. Results: Clinically relevant improvement was observed (46.55 points) when comparing pre-surgical and post-surgical ES-EHM scores. However, no differences between postsurgical and final ES-EHM were detected. Even so, strong correlation was obtained between the following: (1) postsurgical ES-EHM and final ES-EHM scores, (2) ES-EHM and WOMAC scores, and (3) pain and function-related parameters of ES-EHM and WOMAC scores. Standardized response mean (SRM) was 2.99, test–retest reliability expressed by the intraclass correlation coefficient was 0.90 and Cronbach index 0.95. ConclusionsThe Spanish cross-cultural adaptation of the EHM scale shows to be reliable, valid and sensitive to change. Thus, the Spanish medical staff will be able to apply the ES-EHM scale with good scientific support.(AU)

[Effectiveness analysis of revision surgery after total hip arthroplasty assisted by artificial intelligence preoperative planning system].

Objective: To explore the short-term effectiveness of hip revision surgery guided by artificial intelligence preoperative planning (AIHIP) system. Methods: The clinical data of 22 patients (23 hips) who were admitted between June 2019 and March 2023 and met the selection criteria were retrospectively analyzed. There were 12 males and 10 females with an average age of 69.7 years (range, 44-90 years). There were 19 hips in the first revision, 3 hips in the second revision, and 1 hip in the third revision. The causes of revision included 12 hips with prosthesis loosening, 4 hips with acetabular cup loosening, 3 hips with osteolysis, 2 hips with acetabular dislocation, 1 hip with postoperative infection, and 1 hip with prosthesis wear. There were 6 hips in stage ⅡA, 9 hips in stage ⅡB, 4 hips in stage ⅡC, 3 hips in stage ⅢA, and 1 hip in stage ⅢB according to Paprosky staging of acetabular bone defect. The replacement of prosthesis type, operation time, hospitalization stay, ground active condition, and postoperative infection, fracture, prosthesis loosening, and other adverse events were recorded. The function of the affected limb was evaluated by Harris score before operation, at 1 week and 6 months after operation, and the range of motion of the hip joint was compared before operation and at 6 months after operation. Results: The operation time was 85-510 minutes, with an average of 241.8 minutes; the hospitalization stay was 7-35 days, with an average of 15.2 days; the time of disassociation from the walker was 2-108 days, with an average of 42.2 days. All the 22 patients were followed up 8-53 months (mean, 21.7 months). No adverse events such as prosthesis loosening or infection occurred in the rest of the patients, except for postoperative hematoma of the thigh in 1 patient and dislocation of the hip in 1 hip. The matching degree of acetabular cup was completely matched in 22 hips and mismatched in 1 hip (+2), the matching rate was 95.65%. The matching degree of femoral stem was completely matched in 22 hips and generally matched in 1 hip (-1), and the matching rate was 100%. The Harris scores were 55.3±9.8 and 89.6±7.2 at 1 week and 6 months after operation, respectively, which significantly improved when compared with before operation (33.0±8.6, P<0.05), and further improved at 6 months after operation than at 1 week after operation ( P<0.05). The function of hip joint was evaluated by Harris score at 6 months after operation, and 21 hips were good and 2 hips were moderate, which could meet the needs of daily life. The range of motion of hip joint was (111.09±10.11)° at 6 months after operation, which was significantly different from (79.13±18.50)° before operation ( t=-7.269, P<0.001). Conclusion: AIHIP system can improve the accuracy of revision surgery, reduce the difficulty of surgery, and achieve good postoperative recovery and satisfactory short-term effectiveness.

[Estimation of acetabular cup prosthesis coverage rate in total hip arthroplasty based on X-ray films].

Objective: To explore the method of accurately estimating the acetabular cup prosthesis coverage rate (hereinafter referred to as "cup coverage rate") in total hip arthroplasty (THA) based on X-ray films, and to determine the effective parameters that can be used to estimate the cup coverage rate. Methods: The three-dimensional printed pelvic models were established based on CT data of 16 healthy pelvis, and the acetabular prosthesis were implanted according to conventional THA procedure. The length and width of the uncovered area of the acetabular cup prosthesis were measured by a modified X-ray recording method with a rotating C-arm X-ray machine, and the cup coverage rate was calculated. Then the differences among the traditional anteroposterior X-ray recording method, the modified method, and actual measurement on pelvic model were statistically analyzed. The correlation between the area of the uncovered area of the prosthesis and its width and length was analyzed by using multiple linear regression analysis. Results: The cup coverage rates of traditional method, modified method, and actual measurement were 78.22%±3.36%, 86.74%±3.61%, and 89.62%±2.62%, respectively, with significant differences ( P<0.05). The results of multiple linear regression analysis showed that the width and length were positively linear with the uncovered area of the prosthesis, and the regression equation was as follows: uncovered area of the prosthesis=-21.192+0.248×width+0.140×length, and the coefficient of determination R 2=0.857, P<0.001. Conclusion: Compared with the traditional method, the modified method can more accurately evaluate the cup coverage rate during THA, and the width of the uncovered area of the prosthesis can be used as an effective reference for the cup coverage rate.

Elevated cobalt levels in metal-on-polyethylene knee megaprostheses: a prospective 1-year cohort study of 56 patients with hip and knee megaprostheses.

BACKGROUND AND PURPOSE: Concerns have emerged regarding elevated levels of cobalt and chromium in patients with metal-on-metal megaprostheses. This prospective study aims to identify systemic cobalt and chromium levels in metal-on-polyethylene knee and hip megaprostheses and their associations with other factors. METHODS: 56 patients underwent knee or hip megaprosthesis surgery at 2 sarcoma centers. Serum cobalt and chromium levels were measured preoperatively and thrice within the first year using inductively coupled plasma mass spectrometry. RESULTS: A statistically significant difference in serum cobalt levels (1.4 ppb; 95% confidence interval [CI] 0.0-3.3) was observed 1 year after knee megaprosthesis surgery compared with preoperative levels. In contrast no difference in chromium levels was observed after 1 year compared with preoperative levels (0.05 ppb; CI 0.0-0.8). An association between younger age, higher eGFR, and increased cobalt levels was observed. No significant correlations were found between ion levels and resection length or the number of modular connections. CONCLUSION: We found elevated serum ion levels in metal-on-polyethylene knee megaprostheses in contrast to metal-on-polyethylene hip megaprostheses. Furthermore, a positive correlation between cobalt and chromium levels, and between cobalt and eGFR was identified, along with a negative correlation between cobalt and age. This study highlights the importance of monitoring systemic cobalt and chromium levels in patients with megaprostheses.

Small design modifications can improve the primary stability of a fully coated tapered wedge hip stem.

Increasing the stem size during surgery is associated with a higher incidence of intraoperative periprosthetic fractures in cementless total hip arthroplasty with fully coated tapered wedge stems, especially in femurs of Dorr type A. If in contrast a stem is implanted and sufficient primary stability is not achieved, such preventing successful osseointegration due to increased micromotions, it may also fail, especially if the stem is undersized. Stem loosening or periprosthetic fractures due to stem subsidence can be the consequence. The adaptation of an established stem design to femurs of Dorr type A by design modifications, which increase the stem width proximally combined with a smaller stem tip and an overall shorter stem, might reduce the risk of distal locking of a proximally inadequately fixed stem and provide increased stability. The aim of this study was to investigate whether such a modified stem design provides improved primary stability without increasing the periprosthetic fracture risk compared to the established stem design. The established (Corail, DePuy Synthes, Warsaw, IN, US) and modified stem designs (Emphasys, DePuy Synthes, Warsaw, IN, US) were implanted in cadaveric femur pairs (n = 6 pairs) using the respective instruments. Broaching and implantation forces were recorded and the contact areas between the prepared cavity and the stem determined. Implanted stems were subjected to two different cyclic loading conditions according to ISO 7206-4 using a material testing machine (1 Hz, 600 cycles @ 80 to 800 N, 600 cycles @ 80 to 1600 N). Translational and rotational relative motions between stem and femur were recorded using digital image correlation. Broaching and implantation forces for the modified stem were up to 40% higher (p = 0.024), achieving a 23% larger contact area between stem and bone (R2 = 0.694, p = 0.039) resulting in a four times lower subsidence during loading (p = 0.028). The slight design modifications showed the desired effect in this in-vitro study resulting in a higher primary stability suggesting a reduced risk of loosening. The higher forces required during the preparation of the cavity with the new broaches and during implantation of the stem could bare an increased risk for intraoperative periprosthetic fractures, which did not occur in this study.

Assessment of Automated Identification of Phases in Videos of Total Hip Arthroplasty Using Deep Learning Techniques.

Background: As the population ages, the rates of hip diseases and fragility fractures are increasing, making total hip arthroplasty (THA) one of the best methods for treating elderly patients. With the increasing number of THA surgeries and diverse surgical methods, there is a need for standard evaluation protocols. This study aimed to use deep learning algorithms to classify THA videos and evaluate the accuracy of the labelling of these videos. Methods: In our study, we manually annotated 7 phases in THA, including skin incision, broaching, exposure of acetabulum, acetabular reaming, acetabular cup positioning, femoral stem insertion, and skin closure. Within each phase, a second trained annotator marked the beginning and end of instrument usages, such as the skin blade, forceps, Bovie, suction device, suture material, retractor, rasp, femoral stem, acetabular reamer, head trial, and real head. Results: In our study, we utilized YOLOv3 to collect 540 operating images of THA procedures and create a scene annotation model. The results of our study showed relatively high accuracy in the clear classification of surgical techniques such as skin incision and closure, broaching, acetabular reaming, and femoral stem insertion, with a mean average precision (mAP) of 0.75 or higher. Most of the equipment showed good accuracy of mAP 0.7 or higher, except for the suction device, suture material, and retractor. Conclusions: Scene annotation for the instrument and phases in THA using deep learning techniques may provide potentially useful tools for subsequent documentation, assessment of skills, and feedback.

Midterm Comparative Analysis of Short Femoral Stem Survivorship in Dorr Type A Femurs.

Background: Proximal-distal mismatch has emerged as a prominent concern in Dorr type A femoral morphology, prompting the exploration of short stems as promising alternatives to conventional stems. This study aimed to evaluate clinical and radiographic outcomes of total hip arthroplasty (THA) using short femoral stems in Dorr type A proximal femoral morphology with a minimum follow-up of 5 years. Methods: Patients with short femoral stems in Dorr type A between 2011 and 2017 were included. Patients with the Short Modular Femoral (SMF) stem and Metha stem were recruited and patients with a shortened tapered stem (Tri-Lock BPS) were matched by propensity score matching based on age, sex, body mass index, calcar to canal ratio, and diagnosis. Patient-reported outcomes and the presence of thigh pain were assessed at 5 years postoperatively. Revision rate, complication rate, and radiographic outcomes were also assessed and compared. Results: Twenty-two cases (81%) in the SMF stem and 43 cases (65%) in the Metha stem had more than 5 years of follow-up data available. The SMF stem showed a higher failure rate than the other 2 groups, with 18% requiring revision surgery in the SMF stem compared to 4.6% in the Metha stem, and 2.3% in the Tri-Lock BPS. The SMF stem showed considerable complications such as stem position change and lateral cortical hypertrophy with inferior clinical outcomes than the other 2 stem groups. When the Metha stem and the Tri-Lock BPS groups were compared, more intraoperative fractures were observed in the Metha stem, whereas stress shielding and anterior thigh pain were significantly more prevalent in the Tri-Lock BPS. Conclusions: The SMF stem might be less reliable than previously reported, showing a high failure rate and increased radiologic complications. Thus, its use for THA in Dorr Type A femurs needs caution. On the other hand, the Metha stem showed comparable outcomes to the shortened tapered Tri-Lock BPS.

Reoperation risk of periprosthetic fracture after primary total hip arthroplasty using a collared cementless or a taper-slip cemented stem.

Aims: The aim of this study was to determine both the incidence of, and the reoperation rate for, postoperative periprosthetic femoral fracture (POPFF) after total hip arthroplasty (THA) with either a collared cementless (CC) femoral component or a cemented polished taper-slip (PTS) femoral component. Methods: We performed a retrospective review of a consecutive series of 11,018 THAs over a ten-year period. All POPFFs were identified using regional radiograph archiving and electronic care systems. Results: A total of 11,018 THAs were implanted: 4,952 CC femoral components and 6,066 cemented PTS femoral components. Between groups, age, sex, and BMI did not differ. Overall, 91 patients (0.8%) sustained a POPFF. For all patients with a POPFF, 16.5% (15/91) were managed conservatively, 67.0% (61/91) underwent open reduction and internal fixation (ORIF), and 16.5% (15/91) underwent revision. The CC group had a lower POPFF rate compared to the PTS group (0.7% (36/4,952) vs 0.9% (55/6,066); p = 0.345). Fewer POPFFs in the CC group required surgery (0.4% (22/4,952) vs 0.9% (54/6,066); p = 0.005). Fewer POPFFs required surgery in males with a CC than males with a PTS (0.3% (7/2,121) vs 1.3% (36/2,674); p < 0.001). Conclusion: Male patients with a PTS femoral component were five times more likely to have a reoperation for POPFF. Female patients had the same incidence of reoperation with either component type. Of those having a reoperation, 80.3% (61/76) had an ORIF, which could greatly mask the size of this problem in many registries.

Two-stage revision for periprosthetic joint infection after hip and knee arthroplasty.

Aims: Histology is widely used for diagnosis of persistent infection during reimplantation in two-stage revision hip and knee arthroplasty, although data on its utility remain scarce. Therefore, this study aims to assess the predictive value of permanent sections at reimplantation in relation to reinfection risk, and to compare results of permanent and frozen sections. Methods: We retrospectively collected data from 226 patients (90 hips, 136 knees) with periprosthetic joint infection who underwent two-stage revision between August 2011 and September 2021, with a minimum follow-up of one year. Histology was assessed via the SLIM classification. First, we analyzed whether patients with positive permanent sections at reimplantation had higher reinfection rates than patients with negative histology. Further, we compared permanent and frozen section results, and assessed the influence of anatomical regions (knee versus hip), low- versus high-grade infections, as well as first revision versus multiple prior revisions on the histological result at reimplantation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), chi-squared tests, and Kaplan-Meier estimates were calculated. Results: Overall, the reinfection rate was 18%. A total of 14 out of 82 patients (17%) with positive permanent sections at reimplantation experienced reinfection, compared to 26 of 144 patients (18%) with negative results (p = 0.996). Neither permanent sections nor fresh frozen sections were significantly associated with reinfection, with a sensitivity of 0.35, specificity of 0.63, PPV of 0.17, NPV of 0.81, and accuracy of 58%. Histology was not significantly associated with reinfection or survival time for any of the analyzed sub-groups. Permanent and frozen section results were in agreement for 91% of cases. Conclusion: Permanent and fresh frozen sections at reimplantation in two-stage revision do not serve as a reliable predictor for reinfection.

Cemented dual-mobility constructs in uncemented revision acetabular components.

Aims: Dislocation remains a leading cause of failure following revision total hip arthroplasty (THA). While dual-mobility (DM) bearings have been shown to mitigate this risk, options are limited when retaining or implanting an uncemented shell without modular DM options. In these circumstances, a monoblock DM cup, designed for cementing, can be cemented into an uncemented acetabular shell. The goal of this study was to describe the implant survival, complications, and radiological outcomes of this construct. Methods: We identified 64 patients (65 hips) who had a single-design cemented DM cup cemented into an uncemented acetabular shell during revision THA between 2018 and 2020 at our institution. Cups were cemented into either uncemented cups designed for liner cementing (n = 48; 74%) or retained (n = 17; 26%) acetabular components. Median outer head diameter was 42 mm. Mean age was 69 years (SD 11), mean BMI was 32 kg/m2 (SD 8), and 52% (n = 34) were female. Survival was assessed using Kaplan-Meier methods. Mean follow-up was two years (SD 0.97). Results: There were nine cemented DM cup revisions: three for periprosthetic joint infection, three for acetabular aseptic loosening from bone, two for dislocation, and one for a broken cup-cage construct. The two-year survivals free of aseptic DM revision and dislocation were both 92%. There were five postoperative dislocations, all in patients with prior dislocation or abductor deficiency. On radiological review, the DM cup remained well-fixed at the cemented interface in all but one case. Conclusion: While dislocation was not eliminated in this series of complex revision THAs, this technique allowed for maximization of femoral head diameter and optimization of effective acetabular component position during cementing. Of note, there was only one failure at the cemented interface.

Revision total hip arthroplasty using a modular fluted, tapered revision femoral component and interlocking screws in Vancouver B3 periprosthetic fractures with insufficient bone at the isthmus.

Aims: Revision total hip arthroplasty in patients with Vancouver type B3 fractures with Paprosky type IIIA, IIIB, and IV femoral defects are difficult to treat. One option for Paprovsky type IIIB and IV defects involves modular cementless, tapered, revision femoral components in conjunction with distal interlocking screws. The aim of this study was to analyze the rate of reoperations and complications and union of the fracture, subsidence of the stem, mortality, and the clinical outcomes in these patients. Methods: A total of 46 femoral components in patients with Vancouver B3 fractures (23 with Paprosky type IIIA, 19 with type IIIB, and four with type IV defects) in 46 patients were revised with a transfemoral approach using a modular, tapered, cementless revision Revitan curved femoral component with distal cone-in-cone fixation and prospectively followed for a mean of 48.8 months (SD 23.9; 24 to 112). The mean age of the patients was 80.4 years (66 to 100). Additional distal interlocking was also used in 23 fractures in which distal cone-in-cone fixation in the isthmus was < 3 cm. Results: One patient (2.2%) died during the first postoperative year. After six months, 43 patients (93.5%) had osseous, and three had fibrous consolidation of the fracture and the bony flap, 42 (91.3%) had bony ingrowth and four had stable fibrous fixation of the stem. No patient had radiolucency around the interlocking screws and no screw broke. One patient had non-progressive subsidence and two had a dislocation. The mean Harris Hip Score increased from of 57.8 points (SD 7.9) three months postoperatively to 76.1 points (SD 10.7) 24 months postoperatively. Conclusion: The 2° tapered, fluted revision femoral component with distal cone-in-cone-fixation, combined with additional distal interlocking in patients with bony deficiency at the isthmus, led to reproducibly good results in patients with a Vancouver B3 fracture and Paprosky type IIIA, IIIB, and IV defects with regard to union of the fracture, subsidence or loosening of the stem, and clinical outcomes.

How modular porous metal augments have changed the management of acetabular bone loss at primary or revision total hip arthroplasty.

The advent of modular porous metal augments has ushered in a new form of treatment for acetabular bone loss. The function of an augment can be seen as reducing the size of a defect or reconstituting the anterosuperior/posteroinferior columns and/or allowing supplementary fixation. Depending on the function of the augment, the surgeon can decide on the sequence of introduction of the hemispherical shell, before or after the augment. Augments should always, however, be used with cement to form a unit with the acetabular component. Given their versatility, augments also allow the use of a hemispherical shell in a position that restores the centre of rotation and biomechanics of the hip. Progressive shedding or the appearance of metal debris is a particular finding with augments and, with other radiological signs of failure, should be recognized on serial radiographs. Mid- to long-term outcomes in studies reporting the use of augments with hemispherical shells in revision total hip arthroplasty have shown rates of survival of > 90%. However, a higher risk of failure has been reported when augments have been used for patients with chronic pelvic discontinuity.