Browsing by Author "Zamora, Tomas"
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- ItemA Best-Fit of an Anatomic Tibial Baseplate Closely Parallels the Flexion-Extension Plane and Covers a High Percentage of the Proximal Tibia(2021) Nedopil, Alexander J.; Zamora, Tomas; Shelton, Trevor; Howell, Stephen M.; Hull, MauryThere are no reports of in vivo internal-external (I-E) rotational alignment and coverage of the proximal tibia after performing a best-fit method of an anatomically designed and asymmetrically shaped tibial baseplate during calipered kinematically aligned (KA) total knee arthroplasty (TKA). We hypothesized that a best-fit plane sets the anterior-posterior (A-P) axis of the anatomic baseplate closely parallel to the flexion-extension (F-E) plane of the knee and covers a high percentage of the proximal tibia. A total of 145 consecutive primary TKAs were prospectively collected. The calipered KA method and verification checks set the positions and orientations of the components without ligament release in all knees without restrictions on the preoperative deformities. A best-fit method selected one of six trials of anatomic baseplates that maximized coverage and set I-E rotation parallel to and within the cortical edge of the proximal tibia. The angle between the transverse axes of the components (i.e., the deviation of the A-P axis of the anatomic baseplate from the F-E plane of the native knee) and the cross-sectional area (CSA) of the proximal tibia were measured on postoperative computerized tomographic scans. The mean deviation of the anatomic baseplate from the F-E plane was 2-degree external +/- 5degrees. The mean coverage of the proximal tibia was 87 +/- 6% (CSA of baseplate from the manufacturer/CSA of proximal tibiax100). The anatomic baseplate and best-fit method adequately set I-E rotation of the baseplate closely parallel to the F-E plane of the knee and cover a high percentage of the proximal tibia.
- ItemCan the Surgical Apgar Score predict morbidity and mortality in general orthopaedic surgery?(2012) Urrutia, Julio; Valdes, Macarena; Zamora, Tomas; Canessa, Valentina; Briceno, JorgePurpose The Surgical Apgar Score (SAS) is a simple tally based on intra-operative heart rate, blood pressure and blood loss; it predicts 30-day major postoperative complications and mortality in different surgical fields, but no validation has been performed in general orthopaedic surgery.
- ItemHigh prevalence of deep vein thrombosis in elderly hip fracture patients with delayed hospital admission(2020) Bengoa, Francisco; Vicencio, Gerardo; Schweitzer, Daniel; Lira, Maria Jesus; Zamora, Tomas; Klaber, IanivPurpose Deep vein thrombosis (DVT) is a common complication in hip fracture patients, associated with significant morbidity and mortality. Research has focused on postoperative DVT, with scant reports on preoperative prevalence. The aim of this study was to describe the prevalence of preoperative DVT in patients accessing medical care >= 48 h after a hip fracture. Methods We included elderly patients admitted >= 48 h after sustaining a hip fracture, between September 2015 and October 2017. Patients with a previous episode of DVT, undergoing anticoagulation therapy, with pathologic fractures or undergoing cancer treatment were excluded. Of 273 patients, 59 were admitted at least 48 h after the fracture. DVT screening by Doppler ultrasound of both lower extremities was carried upon hospital admission. We recorded age, sex, Charlson comorbidity index and ASA score, fracture type, time since injury, time from admission to surgery and total length of hospital stay. Results We studied 41 patients, 79 (+/- 10.34) years old. The delay from injury to admission was 120 h (48-696 h). Seven patients (17.1%) had a DVT upon admission. There were no significant differences between patients with and without DVT, regarding time from admission to surgery or the total length of the hospital stay. Conclusions The prevalence of DVT in patients admitted >= 48 h after a hip fracture was 17.1%. The diagnosis and management of DVT did not increase time to surgery or hospital stay. Our results suggest routine screening for DVT in patients consulting emergency services >= 48 h after injury.
- ItemInter- and intra-observer agreement using the new AOSpine sacral fracture classification, with a comparison between spine and pelvic trauma surgeons(2022) Meissner-Haecker, Arturo; Diaz-Ledezma, Claudio; Klaber, Ianiv; Zamora, Tomas; Valencia, Manuel; Camino-Willhuber, Gaston; Astur, Nelson; Yurac, Ratko; Valacco, Marcelo; Urrutia, JulioBackground: Sacral fractures treatment frequently involves both spine and pelvic trauma surgeons; therefore, a consistent communication among surgical specialists is required. We independently assessed the new AOSpine sacral fracture classification's agreement from the perspective of spine and pelvic trauma surgeons. Methods: Complete computerized tomography (CT) scans of 80 patients with sacral fractures were selected and classified using the new AOSpine sacral classification system by six spine surgeons and three pelvic trauma surgeons. After four weeks, the 80 cases were presented and reassessed by the same raters in a new random sequence. The Kappa coefficient ( K) was used to measure the inter-and intra-observer agreement. Results: The inter-observer agreement considering the fracture severity types (A, B, or C) was substantial for spine surgeons ( K= 0.68 [0.63 - 0.72]) and pelvic trauma surgeons ( K= 0.74 (0.64 - 0.84). Regarding the subtypes, both groups achieved moderate agreement with K= 0.52 (0.49 - 0.54) for spine surgeons and K= 0.51 (0.45 - 0.57) for pelvic trauma surgeons. The intra-observer agreement considering the fracture types was substantial for spine surgeons ( K= 0.74 [0.63 - 0.75]) and almost perfect for pelvic trauma surgeons ( K= 0.84 [0.74 - 0.93]). Concerning the subtypes, both groups achieved substantial agreement with, K= 0.61 (0.56 - 0.67) for spine surgeons and K= 0.68 (0.62 - 0.74) for pelvic trauma surgeons. Conclusion: This classification allows an adequate communication for spine surgeons and pelvic trauma surgeons at the fracture severity type, but the agreement is only moderate at the subtype level. Future prospective studies are required to evaluate whether this classification allows for treatment recommendations and establishing prognosis in patients with sacral fractures. @ 2021 Elsevier Ltd. All rights reserved.
- ItemRadiographic Assessment of Bone Quality Using 4 Radiographic Indexes: Canal Diaphysis Ratio Is Superior(2024) Faundez, Jorge; Carmona, Maximiliano; Klaber, Ianiv; Zamora, Tomas; Botello, Eduardo; Schweitzer, DanielBackground: Osteoporosis increases the risk of periprosthetic fracture and loosening in hip arthroplasty. Many methods have been proposed to assess bone quality in X-rays, including both qualitative such as the Dorr classification and quantitative such as the Calcar-Canal Ratio (CCR) and Cortical -Thickness index/Canal-Bone ratio (CTI/CBR). The Canal-Diaphysis ratio (CDR) has been described as a predictor for hip fragility fractures; however, its relationship with bone mineral density (BMD) has not been described. The purpose of this study was to evaluate the correlation of the Dorr classification, CCR, CTI/CBR, and CDR with BMD of the proximal femur in patients without hip fracture. Methods: Forty-seven patients over 45 years of age who had less than 6 months between radiographs and dual -energy X-ray absorptiometry were evaluated. Measurements of CCR, CBR, CDR, and Dorr classification were performed in all radiographs by 2 independent observers. Results: The CDR had a high correlation (r = 0.74, P=<0.01) with BMD, whereas the CTI/CBR had a moderate correlation (r = 0.49, P=<0.01), and the CCR had no correlation with BMD (r = 0.06, P = .96). When evaluating the receiver operating characteristic curve, CDR showed the best performance (area under curve [AUC] = 0.75) followed by CBR (AUC = 0.73) and CCR (AUC = 0.61). The optimal cutoff value for the CDR was 0.49, with 100% sensitivity and 58% specificity. The inter- and intra-observer variability was good for all methods. No differences were found between Dorr classification of patients who had or did not have osteoporosis. Conclusion: Of all the analyzed methods, the CDR was found to have the best correlation with BMD. This study proposes the use of CDR as a tool for assessing bone quality when deciding the implant fixation method in hip arthroplasty. (c) 2023 Elsevier Inc. All rights reserved.
- ItemSix Commonly Used Postoperative Radiographic Alignment Parameters Do Not Predict Clinical Outcome Scores after Unrestricted Caliper-Verified Kinematically Aligned TKA(2022) Dhaliwal, Anand; Zamora, Tomas; Nedopil, Alexander J.; Howell, Stephen M.; Hull, Maury L.Background: Unrestricted caliper-verified kinematically aligned (KA) TKA restores patient's prearthritic coronal and sagittal alignments, which have a wide range containing outliers that concern the surgeon practicing mechanical alignment (MA). Therefore, knowing which radiographic parameters are associated with dissatisfaction could help a surgeon decide whether to rely on them as criteria for revising an unhappy patient with a primary KA TKA using MA principles. Hence, we determined whether the femoral mechanical angle (FMA), hip-knee-ankle angle (HKAA), tibial mechanical angle (TMA), tibial slope angle (TSA), and the indicators of patellofemoral tracking, including patella tilt angle (PTA) and the lateral undercoverage of the trochlear resection (LUCTR), are associated with clinical outcome scores. Methods: Forty-three patients with a CT scan and skyline radiograph after a KA TKA with PCL retention and medial stabilized design were analyzed. Linear regression determined the strength of the association between the FMA, HKA angle, PTS, PTA, and LUCTR and the forgotten joint score (FJS), Oxford knee score (OKS), and KOOS Jr score obtained at a mean of 23 months. Results: There was no correlation between the FMA (range 2 degrees varus to -10 degrees valgus), HKAA (range 10 degrees varus to -9 degrees valgus), TMA (range 10 degrees varus to -0 degrees valgus), TSA (range 14 degrees posterior to -4 degrees anterior), PTA (range, -10 degrees medial to 14 degrees lateral), and the LUCTR resection (range 2 to 9 mm) and the FJS (median 83), the OKS (median 44), and the KOOS Jr (median 85) (r = 0.000 to 0.079). Conclusions: Surgeons should be cautious about using postoperative FMA, HKAA, TMA, TSA, PTA, and LUCTR values within the present study's reported ranges to explain success and dissatisfaction after KA TKA.
- ItemSpondylolysis and spina bifida occulta in pediatric patients: prevalence study using computed tomography as a screening method(2016) Urrutia, Julio; Cuellar, Jorge; Zamora, TomasThe prevalence of spondylolysis reported from radiograph-based studies has been questioned in recent computed tomography (CT)-based studies in adults; however, no new data are available in pediatric patients. Spina bifida occulta (SBO), which has been associated to spondylolysis, may be increasing its prevalence, according to recent studies in adults in the last decades, but without new data in pediatric patients. We aimed to determine the prevalence of spondylolysis and SBO in pediatric patients using abdomen and pelvis CT as a screening tool.
- ItemTraction images heavily influence lateral wall measurement in trochanteric hip fractures. A prospective study(2023) Carmona, Maximiliano; Gonzalez, Nicolas; Segovia, Javier; de Amesti, Martin; Zamora, Tomas; Schweitzer, DanielIntroduction: hip fracture represents a global health problem, with a high morbidity and mortality rate and an increasing incidence. The treatment of trochanteric fractures is reduction and osteosynthesis, and implant selection depends mainly on the stability of the fracture and lateral wall competence. Lateral wall competence has gained relevance in recent years, which led to the modification of the AO/OTA classification. However, determination of lateral wall integrity is difficult from plain radiographs; the influence of images with traction on its measurement has not been evaluated.
- ItemWhich Asymmetric Tibial Component Is Optimally Designed for Calipered Kinematically Aligned Total Knee Arthroplasty?(2022) Nedopil, Alexander J.; Zamora, Tomas; Delman, Connor; Howell, Stephen M.; Hull, Maury L.Calipered kinematically aligned (KA) total knee arthroplasty (TKA) restores the patient's prearthritic joint lines and sets internal-external rotation of the tibial component parallel to the flexion-extension (FE) plane, which is not a mechanical alignment (MA) target. Two asymmetric tibial components designed for MA set the tibial component to either a femoral component (FC) target or a tibial tubercle (TT) target. The study determined the optimal asymmetric tibial component to use with KA as the one with smaller IE deviation from the MA target, greater coverage of tibial resection, and lower incidence of cortical overhang. The study included 40 patients treated with bilateral calipered KA TKA with different asymmetric tibial components in opposite knees. A best-fit of a kinematic tibial template to the tibial resection set the template's slot parallel to the knee's FE plane. Each asymmetric tibial component's anterior-posterior (AP) axis was set parallel to the slot. Computer tomography analysis determined the IE deviation (-internal/+external) of each tibial component from its MA target, tibial resection coverage by the baseplate and insert, and incidence of cortical overhang. The patient-reported Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) determined outcomes. The mean IE deviation from the MA target was 2 degrees external for the FC-target asymmetric tibial component and -8 degrees internal for the TT-target asymmetric tibial component ( p <0.001). Tibial resection coverage by the baseplate (insert) was 88% (84%) for the FC target and 84% (79%) for the TT target ( p <0.001 for baseplate and insert). The FC target insert covered 3mm more of the posterolateral resection ( p <0.001). Posteromedial coverage was comparable. The incidence of cortical overhang was 2.5% for each baseplate. There was no difference in FJS and OKS. When performing calipered KA, the more optimal design was the asymmetric tibial component with the FC target because of the smaller deviation from its MA target and the greater coverage of the tibial resection by the baseplate and insert.