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Background: Interest in cementless total knee arthroplasty (TKA) has increased with advancement of biomaterials and implant design and associated improved longevity. We sought to evaluate the gap patterns and radiolucent zones radiographically for 2 newer-generation cementless TKA designs. Methods: We retrospectively reviewed our single-institution database between January 2017 and December 2019. We identified patients with a porous keeled tibia baseplate with 4-bullet cruciform spikes and peri-apatite coated femoral component (study group 1) and patients who received a cementless porous coated femoral component and rotating platform tibia baseplate with 4 peripheral porous coated pegs around a central cone (study group 2). We identified gap patterns at 6 weeks and at 1 year or more postoperatively on radiographs, noting indications for reoperation. Results: We identified 228 patients in study group 1 and 41 patients in study group 2. At 1-year follow-up, we found evidence of resolved femoral gaps in 52 (72.2%) of 72 patients in study group 1 and 10 (58.8%) of 17 patients in study group 2 (p = 0.124). We identified 27 (84.3%) of 32 patients in study group 1 and 7 (70.0%) of 10 patients in study group 2 with resolved tibia gaps (p = 0.313). After 1 year, there were significantly more Zone 3 a femoral zonal radiolucent gaps (p = 0.001) and Zone 8 tibia zonal radiolucent gaps (p = 0.002) in study group 2 than in study group 1. There were 4 reoperations for study group 1 and 0 reoperations for study group 2. Conclusion: The modern cementless TKA systems have varied gap patterns in postoperative radiographs, which may be attributed to the implant design. Most radiolucent gaps resolve radiographically on follow-up. Contexte : Les perc es dans les biomat riaux et la conception des proth ses, associ es une long vit accrue de ces derni res, ont entra n un regain d'int r t pour l'arthroplastie totale du genou (ATG) non ciment e. Nous avons cherch valuer par radiographie les espaces et les zones radiotransparentes pour 2 ATG de nouvelle g n ration sans ciment. M thodes : Nous avons r trospectivement pass en revue notre base de donn es (un seul tablissement) pour la p riode de janvier 2017 d cembre 2019. Nous y avons rep r les patients ayant re u une pi ce tibiale poreuse quille avec 4 pointes cruciformes et une composante f morale rev tement de peri-apatite (groupe 1) et les patients ayant re u une composante f morale poreuse rev tue non ciment e et une pi ce tibiale en rotation avec 4 plots p riph riques poreux rev tus autour d'un c ne central (groupe 2). Six semaines puis au moins 1 an apr s l'intervention, nous avons identifi sur des radiographies les espaces en notant les indications de r intervention. R sultats : Nous avons tudi 228 patients dans le groupe 1 et 41 patients dans le groupe 2. Au suivi apr s 1 an, nous avons trouv des signes d'espace f moral r sorb chez 52 patients sur 72 (72,2%) du groupe 1 et chez 10 patients sur 17 (58,8%) du groupe 2 (p = 0,124). Nous avons trouv chez 27 patients sur 32 (84,3%) du groupe 1 et 7 patients sur 10 (70,0%) du groupe 2 un espace tibial r sorb (p = 0,313). Apr s 1 an, il y avait consid rablement plus d'espaces radiotransparents dans la zone f morale 3a (p = 0,001) et d'espaces radiotransparents dans la zone tibiale 8 (p = 0,002) dans le groupe 2 que dans le groupe 1. Il y a eu 4 r interventions dans le groupe 1 et aucune dans le groupe 2. Conclusion : Les syst mes d'ATG modernes sans ciment pr sentent des espaces vari s sur les radiographies postop ratoires, ce qui peut tre attribu la conception de la proth se. La plupart des espaces radiotransparents se sont r sorb s la radiographie de suivi., Knee end-stage osteoarthritis is successfully treated with total knee arthroplasty (TKA), with more than 55 000 TKA procedures performed in Canada in 2020-2021 alone. (1) Cemented TKA is typically preferred [...]

Background: The direct lateral (DL) approach to total hip arthroplasty is more commonly used than the newer direct anterior (DA) approach. Both approaches use collared or collarless femoral stems. We sought to assess implant stability of stem designs implanted with the DL approach and compare outcomes from this cohort with those of a previously reported cohort of patients who underwent arthroplasty with a DA approach. We also sought to determine if early recovery influences differences in migration. Methods: Patients underwent total hip arthroplasty using the DL or the DA approach and were randomized to receive either a collared or collarless, cementless femoral stem. On the day of surgery and at 6 follow-up visits through to 1 year, patients underwent supine radiostereometric imaging to track implant migration. At follow-up visits, patients performed an instrumented walking test to assess their functional ability and logged an average daily step count to assess their activity levels. We assessed whether patient function and activity were correlated with migration. Results: Stem design did not have a significant effect on migration for the DL group (p = 0.894). Compared with the DA group, the DL group migrated significantly less for both collared (p = 0.031) and collarless (p = 0.002) stems. Migration was not correlated with function or activity at any time point (p > 0.05). Conclusion: Most implant migration occurred from the day of surgery to 2 weeks after the operation and stabilized thereafter, suggesting adequate fixation and a low risk for aseptic loosening in both patient groups. Contexte : La voie laterale directe (LD) est utilisee plus frequemment pour effectuer une arthroplastie totale de la hanche (ATH) que la voie anterieure directe (AD), plus recente. Les 2 approches utilisent des tiges femorales avec ou sans collerette. Nous avons evalue la stabilite des modeles de tiges implantes par voie LD et compare les issues de cette cohorte a celles d'une cohorte de patients ayant deja fait l'objet d'une etude qui avaient subi une arthroplastie par voie AD. Nous avons aussi cherche a determiner si le debut du retablissement avait une influence sur des differences dans le risque de migration. Methodes : Des patients devant subir une arthroplastie par voie LD ou AD ont ete repartis aleatoirement en 2 groupes : tiges femorales sans ciment avec ou sans collerette. Le jour de l'intervention et durant 6 visites de suivi la premiere annee, les patients ont subi un examen d'imagerie radiostereometrique en decubitus visant a mesurer la migration de l'implant. Durant les visites de suivi, ils ont fait un test de marche instrumente visant a evaluer leur capacite fonctionnelle et enregistre leur nombre moyen de pas quotidiens, ce qui permet d'evaluer leur niveau d'activite. Nous avons cherche a determiner s'il y avait une correlation entre la migration observee, et la capacite fonctionnelle et le niveau d'activite des patients. Resultats : Le modele de tige n'a pas eu d'effet significatif sur la migration pour le groupe LD (p = 0,894). Par contre, comparativement au groupe AD, on a enregistre chez les patients du groupe LD une migration significativement inferieure pour les tiges avec collerette (p = 0,031) et sans collerette (p = 0,002). Aucune correlation n'a ete observee entre la migration et la capacite fonctionnelle ou le niveau d'activite, peu importe le moment de l'evaluation (p > 0,05). Conclusion : L'essentiel de la migration des implants est survenu dans les 2 semaines suivant l'intervention, puis le processus s'est stabilise, ce qui semble indiquer une fixation adequate et un faible risque de descellement aseptique dans les 2 groupes de patients., Total hip arthroplasty (THA) is the only viable treatment for patients with end-stage osteoarthritis of the hip, and is successful and reliable in improving patients' quality of life, restoring function [...]

Background: Surgical approaches for total knee arthroplasty (TKA) include the medial parapatellar (MPA), subvastus (SV), midvastus (MV), and lateral parapatellar approach (LPA); it remains unclear which approach is superior. Methods: Patients having undergone TKA at our institution were retrospectively organized into matched groups according to surgical approach (MPA, MV, SV, or LPA). Outcomes between the groups were compared using the Short-Form 12 (SF-12), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Society Score (KSS), and range of motion (ROM) up to 2 years postoperative. Results: Sixty-eight MV patients, 8 SV patients, and 4 LPA patients were matched with groups of MPA patients. There was no difference in outcomes between the MPA and MV groups up to 2 years. The SV group had significantly higher SF-12 Physical Composite Score (PCS; p = 0.036) and WOMAC stiffness score (p = 0.014) at 2 years, but significantly lower flexion at 1 year (p = 0.022) than the MPA group. The LPA group had significantly lower SF-12 PCS (p = 0.011) and WOMAC function scores (p = 0.022) at 1 year than the MPA group. Conclusion: There was no significant difference between the MPA and MV approach. The SV approach had some improved long-term outcomes over the MPA aproach (SF-12 and WOMAC), but had significantly lower flexion at 1 year. The LPA group showed inferior outcomes than the MPA group but had more severe valgus preoperative deformity (p = 0.024). Further studies are required to investigate the potential benefit of quadriceps-sparing approaches. Contexte : Les voies chirurgicales d'arthroplastie totale du genou (ATG) sont les suivantes : parapatellaire interne (PI), subvastus (SV), midvastus (MV), et parapatellaire externe (PE); il n'est pas clair quelle voie est superieure. Methodes : Les patients qui ont subi une ATG dans notre etablissement ont ete classes retrospectivement en groupes apparies selon la voie chirurgicale (PI, MV, SV ou PE). Les resultats des differents groupes ont ete compares au moyen du Short-Form 12 (SF-12), de l'indice Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), du score de la Knee Society (KSS) et de l'amplitude du mouvement jusqu'a 2 ans apres l'operation. Resultats : Au total, 68 patients traites par voie MV, 8 par voie SV et 4 par voie PE ont ete apparies avec des groupes de patients traites par voie PI. Il n'y avait aucune difference dans les resultats entre les groupes PI et MV jusqu'a 2 ans. Comparativement au groupe PI, le groupe SV avait des resultats significativement plus eleves pour le score physique fonctionnel (PCS) du SF-12 (p = 0,036) et le score de raideur de l'indice WOMAC (p = 0,014) apres 2 ans, mais une flexion significativement plus faible apres 1 an (p = 0,022). Encore comparativement au groupe PI, le groupe PE avait des resultats significativement plus faibles pour le PCS du SF-12 (p = 0,011) et les scores fonctionnels de l'indice WOMAC (p = 0,022) apres 1 an. Conclusion : Il n'y avait pas de difference significative entre les voies PI et MV. La voie SV offrait de meilleures issues a long terme que la voie PI (SF-12 et WOMAC), mais une flexion significativement plus faible apres 1 an. Le groupe PE a eu des issues moins bonnes que le groupe PI, mais presentait plus souvent une deformation valgus preoperatoire grave (p = 0,024). D'autres etudes seront requises pour etablir les bienfaits potentiels de voies evitant le quadriceps., Many approaches have been described for total knee arthroplasty (TKA), including the medial parapatellar (MPA), subvastus medialis (SV), midvastus (MV), and lateral parapatellar (LPA) approaches. The most commonly used of [...]

Though radiostereometric analysis (RSA) is the gold standard for migration tracking, computed tomography‐based RSA (CT‐RSA) does not require marker beads and is available for clinical adoption. This study investigated CT‐RSA in comparison to RSA for assessing hip implant stability with inducible displacement (ID) examinations. Patients (n = 48) from a previous study returned to be re‐examined for femoral stem stability with CT‐RSA and RSA imaging. Implant migration since patients last follow‐up was calculated as a measure of stability. ID was assessed between alternated leg rotation scans for CT‐RSA and between supine and weight‐bearing scans for RSA. Measurements from ID and double examinations were compared between CT‐RSA and RSA. All stems were well‐fixed with migration <0.2 mm/year. ID measurements were lower with CT‐RSA than RSA for distal translation (mean difference = 0.122 mm, p < 0.0001), total translation (mean difference = 0.158 mm, p < 0.0001), and total rotation (mean difference = 0.449°, p < 0.0001). The ID and double exam were significantly different for total translation and total rotation for CT‐RSA, and significantly different for medial, distal, and total translation, and total rotation for RSA. Precision ranged from 0.049 to 0.130 mm in translation and 0.061° to 0.220° in rotation for CT‐RSA, and from 0.108 to 0.269 mm in translation and 0.151° to 0.670° in rotation for RSA. ID measurements from both CT‐RSA and RSA were minimal, consistent for a cohort with well‐fixed stems. CT‐RSA demonstrated superior precision in all axes compared to RSA. Clinical Significance: Future work should explore the use of CT‐RSA in patients with suspected loosening as a potential diagnostic tool. [ABSTRACT FROM AUTHOR]

Background: Total hip arthroplasty (THA) via the direct anterior approach has increased in popularity in the last decade, with research supporting enhanced early recovery; however, some investigators have reported increased early revision rates in direct anterior THA. We examined outcomes from a single institution's experience with a fully hydroxyapatite-coated collared femoral stem implanted via the anterior or the lateral approach. Method: Patients who had received fully hydroxyapatite-coated collared femoral stems as part of THA surgery performed by 1 of 3 surgeons between January 2012 and September 2017 were identified from our institutional database. We examined revision rates for the 2 approaches and compared them between the 2 groups. We also analyzed outcomes on plain film radiographs obtained immediately postoperatively and at 1 and 2 years. Results: A total of 695 patients received a fully hydroxyapatite-coated collared stem during the study period. Total hip arthroplasty was performed via the direct anterior approach in 281/778 hips (36.1%) and via the direct lateral approach in 497 (63.9%). Nineteen patients (2.5%) underwent subsequent revision surgery; there was no statis tically significant difference in the revision rate between the anterior and lateral approaches (2.5% v. 2.4%, p = 0.95). The mean subsidence of the stem at 1 year was 1.68 mm (standard deviation 11.7 mm). No statistically significant differences were observed between the cohorts for any of the radiographic measurements at either follow-up time Conclusion: We found no significant difference in revision rates between the direct anterior and direct lateral approach. Stem subsidence levels were in keeping with expected values, and no major changes in stem position occurred during the first postoperative year. Surgical approach did not appear to substantially affect biomechanical stem behaviour. Contexte : L'arthroplastie totale de la hanche (ATH) par voie anterieure directe a gagne en popularite dans les 10 dernieres annees, la recherche ayant montre qu'elle favorisait un retablissement rapide; certains chercheurs ont toutefois signale qu'elle etait associee a un taux accru d'operations de revision precoces. Nous avons etudie les issues de l'installation d'une tige femorale a collier entierement recouverte d'hydroxy apatite par voie anterieure ou laterale dans un etablissement. Methodes : Nous avons interroge la base de donnees de notre etablissement pour y recenser les patients ayant subi, entre janvier 2012 et septembre 2017, une ATH au cours de laquelle 1 de 3 chirurgiens a installe une tige femorale a collier entierement recouverte d'hydroxyapatite. Nous avons ensuite examine le taux d'operations de revision pour les 2 approches etudiees, et avons compare les issues des 2 groupes. Nous avons egalement analyse les cliches radiographiques pris immediatement apres l'intervention, de meme de ceux pris aux suivis a 1 et a 2 ans. Resultats : Durant la periode a l'etude, 695 patients se sont fait installer une tige femorale a collier entierement recouverte d'hydroxyapatite. Sur 778 hanches, 281 (36,1 %) avaient subi une ATH par voie anterieure directe, et 497 (63,9 %), une ATH par voie laterale directe. Dix-neuf patients (2,5 %) ont du subsequemment subir une operation de revision; aucune difference statistiquement significative n'a ete observee entre le groupe voie anterieure et le groupe voie laterale en ce qui a trait au taux de revision (2,5 % c. 2,4 %; p = 0,95). L'affaissement moyen de la tige au suivi a 1 an etait de 1,68 mm (ecart type 11,7 mm). Les mesures radiographiques des 2 groupes ne presentaient pas de differences statistiquement significatives, quel que soit le moment du suivi. Conclusion : Nous n'avons constate aucune difference significative dans le taux de revision entre les 2 groupes. L'affaissement observe etait dans les valeurs attendues, et la position de la tige n'avait pas change de facon importante au cours de la premiere annee. La voie chirurgicale utilisee ne semblait pas influencer considerablement le comportement biomecanique de la tige., Total hip arthroplasty (THA) is one of the most reliable and reproducible procedures in orthopedic surgery today, with a success rate as high as 97%.1 With recent advances in implant [...]

Background: Corrosion at the head-neck junction of femoral stems is a rare complication of total hip arthroplasty (THA) with manifestations ranging from subclinical wear to failure. Prior studies have identified a single femoral component design with an increased propensity for catastrophic trunnion failure. The purpose of the present study was to quantify trunnion damage of this femoral component retrieved from patients undergoing revision THA for non-trunnionosis indications. Methods: 24 femoral components from a single manufacturer were identified for study inclusion. Each prosthesis underwent stereomicroscopic inspection. Corrosion and fretting scores were assigned per the Goldberg criteria to quadrants of the trunnion. Material loss was calculated based on cone angles across trunnion quadrants. This was carried out using a coordinate measuring machine that digitised each trunnion surface. Stems were compared to a series of femoral stems with the same trunnion design. Results: 20 of the 24 (83%) trunnions demonstrated corrosion, all 24 trunnions demonstrated fretting. Corrosion scores did not statistically differ with respect to trunnion zone (p = 0.53), while fretting scores were higher in the inferior compared to the superior zones (p < 0.001). There was no significant difference in cone angles assessing material loss between stems (p = 0.25). Conclusions: Evidence of trunnion damage was observed in each stem retrieved for non-trunnionosis revision. Fretting occurred more frequently about the inferior quadrants. However, digitised trunnion shapes were similar between compared stems exhibiting no material loss. Therefore, it is possible that previous reports of trunnion failures for this implant are not a systemic issue, and that further investigation is required. [ABSTRACT FROM AUTHOR]

Component-on-component impingement in total hip arthroplasty may lead to post-operative complications including dislocation. Despite numerous clinical studies focusing on reducing this risk, assessment methods remain limited to qualitative radiography, finite element analysis, and cadaver studies. There is a need for more precise measurements of impingement in the research setting. We aimed to validate a novel RSA-based impingement metric to measure component-on-component impingement in vivo. A phantom experiment of a standard metal-on-polyethylene total hip system was performed. RSA examinations were performed as typical for a traditional weight-bearing RSA exam for large joints. The phantom was placed in 10 possible impinged positions and one neutral position. Double exposure radiographs were taken to measure repeatability. The closest distance between the skirt of the head and the inner circumference of the acetabular cup liner was measured to assess impingement risk. Distances between the closest point of the hood to the edge of the cup in 10 impinged positions ranged from 0.05 to 1.03 mm, with the average being 0.67 mm. In the neutral position, the distance measured is 11.02 mm. Excellent repeatability was observed, with a standard deviation of 0.03 mm with an r value of 0.09. A validated RSA-based risk metric was established to evaluate in vivo hip impingement. A 1 mm threshold may be proposed to define impingement where distances approaching 1.00 mm are at a greater risk of impingement. This simplified metric holds promise for upcoming clinical studies on component-on-component impingement. [ABSTRACT FROM AUTHOR]

In this study we combined empirical data about latency (delays) inherent in the transmission of information via the Internet with psychoacoustic information about the ability of musical performers to synchronize their playing and discern independent musical events. We used this information to determine the feasibility of conducting networked musical performances over local-area networks (LANs), wireless localareanetworks (WLANs), and even wide-areanetworks (WANs), including performance ofmusic that requires relatively tight synchrony of events. The experimental psychoacoustic and performance data we collected implies that successful rhythmically-synchronized networkedperformances can occur if the network latency is less than the time needed to perceive musical events as simultaneous, and less than the ability of the players to synchronize. These stipulations were usually met in performances involving MIDI transmission between two locations thatare less than 400 miles apart (where network latency is below about 20 ms). In a future article we will detail the latency characteristics of networked performances involving transmission of audio streams, In this article we restrict our discussion to MIDI streams, which is far less demanding of network bandwidth. By conducting our tests on commonly available hardware and software, we have shown that networked performances are accessible to both household users and university performers alike.