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Background: This report seeks to clarify whether the dosage and duration of preoperative concurrent corticosteroid use influence postoperative complications after primary total joint arthroplasty (TJA)., Methods: This retrospective single institutional study enrolled 1128 primary TJA cases, including 905 total hip arthroplasties and 223 total knee arthroplasties at a minimum 6 months of follow-up. Mean follow-up period was 51.9 ± 34.1 months (range 6-146). Of all joints, 120 joints (10.6%) were associated with chronic concurrent oral corticosteroid use. Multivariate analysis was performed to identify whether chronic concurrent oral corticosteroid use elevated the risk of postoperative complications including surgical site infection/periprosthetic joint infection, delayed wound healing, periprosthetic fracture, and implant loosening. For chronic concurrent oral corticosteroid user, we determined whether the dosage and duration of preoperative concurrent corticosteroid use influenced postoperative complications and have an effective threshold for postoperative complications using receiver operating characteristic curve analysis., Results: The multivariate analysis revealed that American Society of Anesthesiologist Physical Status 3 was an independent risk factor for postoperative complications, while concurrent oral corticosteroid use was not an independent risk factor. When we compared joints with (n = 13) and without (n = 107) postoperative complications in chronic concurrent oral corticosteroid user, there was no statistical difference in the dosage (P = .97) and duration (P = .69) between the 2 groups. Area under the curve values for the oral corticosteroid dosages and duration were 0.482 and 0.549, respectively., Conclusion: This study revealed that neither dosage nor duration of concurrent oral corticosteroid use was predictive of postoperative complications after TJA. American Society of Anesthesiologist Physical Status 3 is a major factor in postoperative complications after TJA., (Copyright © 2021 Elsevier Inc. All rights reserved.)

In total knee arthroplasty, the surgical transepicondylar axis (SEA) is one of the most reliable rotation axes for stabilizing of the patellofemoral joint. The SEA is identified with reference to the lateral epicondyle and the medial sulcus of the medial epicondyle. However, these two structures rarely appear on the same plane on computed tomography (CT), and it is necessary to take two points in separate images. Many surgeons measure the SEA on the same image (pseudo SEA) instead. We aimed to determine the difference between true SEAs and pseudo SEAs. A total of 31 normal knees and 24 varus knees were included in this study. Three-dimensional (3D) models of the femur were reconstructed from CT images, and a reconstructed plane was made using the International Society of Biomechanics coordinate system. Pseudo SEAs drawn in the plane passing through the lateral epicondyle and medial sulcus were defined as l-SEA and m-SEA, respectively. L-SEA, m-SEA, true SEA, and posterior condylar axis (PCA) were projected onto the International Society of Biomechanics coordinate plane and, "p l-SEA," "p m-SEA," "p true SEA," and "p PCA" were obtained. The true SEA angle was defined as the angle between p true SEA and p PCA. The l-SEA angle or m-SEA angle was defined as the angle between the p l-SEA or p m-SEA and p PCA, respectively. There were no statistically significant differences between true SEA angle (2.64 ± 2.01 degrees) and pseudo SEA angle (l-SEA angle: 2.74 ± 2.07 degrees, m-SEA: 2.54 ± 2.19 degrees). Conversely, 12 knees in the normal group and 2 knees in the varus group had differences of more than 1 degree ( p  = 0.01). Among them, 6 knees in the normal group and 0 knees in the varus group had a difference of 2 degrees or more ( p  = 0.03). In most cases, pseudo SEA can be substituted for true SEA., Competing Interests: None declared., (Thieme. All rights reserved.)

Purpose: It remains to be established whether optical computed tomography (CT)-free and acceleration-based navigation systems differ in terms of implantation accuracy and clinical outcomes for total knee arthroplasty. This randomised prospective study compared the implantation accuracy of these two navigation systems in total knee arthroplasty., Methods: Optical CT-free navigation (ExactechGPS) or acceleration-based navigation (KneeAlign2) was randomly assigned to the left or right knee of 45 patients who underwent a single-stage bilateral total knee arthroplasty: the ExactechGPS (n = 45) and KneeAlign2 groups (n = 45) were compared. Component alignments were evaluated using three-dimensional computed tomography and radiography at pre- and post-surgery. Implantation accuracy of the component alignment, proportion of outliers, postoperative range of motion, and Japanese Orthopaedic Association (JOA) score were compared between the systems., Results: The implantation accuracies of the lower-extremity mechanical alignment, coronal femoral component angle, coronal tibial component angle, sagittal femoral component, axial femoral angle, and axial tibial angle had no significant difference between the groups. The implantation accuracy of the sagittal tibial component angle was superior in the ExactechGPS than the KneeAlign2 group (1.3° vs. 1.8°, P = 0.034). The proportions of outliers, range of motion, and JOA score had no significant difference between the groups., Conclusion: In the tibial sagittal plane, there was a significant difference in the implantation accuracy, but its difference did not affect the clinical outcomes. Both navigation systems have clinically acceptable implantation accuracy., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: This study aimed to investigate the effect of diabetes mellitus (DM) on knee extension/flexion angle and its early clinical course after total knee arthroplasty (TKA)., Methods: Patients who received TKA were retrospectively divided into two groups based on haemoglobinA1c level; the DM group (23 knees) and the control group (23 knees matched for baseline characteristics). The passive knee extension/flexion angle, gait speed and Japanese Orthopaedic Association (JOA) score were evaluated preoperatively and at 1, 6 and 12 months postoperatively., Results: There was no significant difference in the passive knee flexion angle at 1 and 6 months postoperatively between the groups ( p  = .302, p  = .160, respectively). The passive knee flexion angle was significantly lower at 12 months postoperatively in the DM group than the control group ( p  = .014). In the DM group, the passive knee flexion angle at 6 and 12 months significantly decreased compared with that at 1 month postoperatively ( p  = .021, p  < .001, respectively). There were no significant differences in the knee extension angle, gait speed and JOA score between the groups., Conclusion: Patients with DM are likely to experience passive knee flexion angle exacerbating from 1 to 6 months after TKA.

Purpose: During total knee arthroplasty, few rotating reference axes can be reliably used after tibial resection. We speculated that a line that passes through the lateral edge of the posterior cruciate ligament (PCL) at its tibial attachment after resection and the most prominent point of the tibial tubercle [after-tibial resection (ATR) line] will provide a good reference axis. In this study, we aimed to evaluate the association between ATR and Akagi's lines., Materials and Methods: In this case-control simulation study, we retrospectively evaluated 38 patients with varus knee and 28 patients with valgus knee. We defined the reference cutting plane as 10 mm distal from the lateral articular surface of the tibia in varus group and as 7 mm distal from the medial articular surface in the valgus group. We measured angles between Akagi's line and the ATR line (ATR line angle) as well as between Akagi's line and 1/3 Akagi's line (1/3 Akagi's line angle), which passes through the midpoint of PCL and the medial third of the patellar tendon. We used paired t-tests to determine the significance of differences between these angles, with p < 0.05 indicating statistical significance. Intra- and interclass correlation coefficients for the reproducibility of 1/3 Akagi's line angle and ATR line angle were analyzed by two surgeons., Results: We found that 1/3 Akagi's line angle was 10.2° ± 1.3° in the varus group and 10.9° ± 1.3° in the valgus group (p = 0.017). The ATR line was positioned externally compared with Akagi's line in all patients. Mean ATR line angles at 0°, 3° and 7° posterior slopes were 6.1° ± 1.9°, 5.8° ± 2.0° and 6.0° ± 1.7° in the varus group and 6.3° ± 2.3°, 6.2° ± 2.3° and 5.4° ± 2.1° in the valgus group, respectively. There were no significant differences in the ATR line angle between the varus and valgus groups. (p = 0.34-0.67) Intra- and interclass correlation coefficients for the reproducibility of 1/3 Akagi's line angle were 0.936 and 0.986 and those for the reproducibility of ATR line angle were 0.811 and 0.839., Conclusions: The ATR line was positioned between Akagi's line and 1/3 Akagi's line in all patients and was a valid option for evaluating rotational tibial alignment after tibial resection., Competing Interests: The authors have declared that no competing interests exist.

Objectives: Limb lengthening after total knee arthroplasty (TKA) has been reported in some cases, all of which were evaluated using two-dimensional images. To our knowledge, no case has been evaluated using three-dimensional (3D) images. We investigated 3D limb lengthening after TKA., Methods: We simulated 100 varus knees using 3D templating software. Virtual TKA was performed to maintain the original joint line by conducting a measured-resection technique. We examined the relationships of 3D distance between the femoral head center and ankle center before and after TKA, degree of hip-knee-ankle angle (HKA) improvement, and degree of flexion contracture angle improvement., Results: All cases showed limb lengthening (average, 9.4 ± 6.0 mm). The coefficients of correlation with limb lengthening and the degree of HKA improvement and the degree of flexion contracture angle improvement were good (0.730 and 0.751, respectively). The correlation between the degree of total improvement (the degree of HKA improvement + the degree of flexion contracture angle improvement) and limb lengthening was strong (r = 0.896)., Conclusion: The expected limb lengthening when performing measured-resection TKA is expressed as 0.58 × (the degree of HKA improvement + the degree of flexion contracture angle improvement) mm and is a useful index.

Medial collateral ligament (MCL) pie-crusting technique in total knee arthroplasty (TKA) is one of the methods of medial release. The effects and risks of blade pie-crusting have been reported in previous studies. However, only a few have reported the safety and efficacy of needle pie-crusting. In this cadaveric study, we quantitatively evaluated the amount of gap change by MCL needle pie-crusting. We investigated five knees of four fresh human cadavers and performed posterior-stabilized TKA. Only deep MCL release as the medial release was conducted. We punctured the MCL from the deep layer to the superficial layer using a 18 G needle in a 90-degree flexion position for 0, 10, 20, 50, 75, and 100 times. Medial and lateral gaps were measured accurately with a balancer at determined times in 0 and 90-degree flexion positions. Changes in medial and lateral gaps were not significant differences in flexion and extension position. However, in 90-degree flexion, medial gap changes were tended to be larger than lateral gap changes. A 0.6 mm additional medial release and a 0.2 mm additional lateral release were found per 10 times pie crust in flexion position (100 times, p : 0.08). However, large differences existed among the cases. Needle pie-crusting is safer than blade pie-crusting because of the small efficacy of one-time pie crust. MCL needle pie-crusting showed varied effects for each case. This result indicates the risk of relaxation of an unexpected gap. Caution should be taken when choosing between needle pie-crusting and blade pie-crusting., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: The "grand-piano sign" is a well-known indicator of proper rotational femoral alignment. We investigated changes in the shape of the femoral anterior cutting plane by changing the rotational alignment, anterior portion depth, and cutting plane flexion angle., Methods: We simulated various cutting planes after cutting the anterior portion of the femur next to the distal femoral osteotomy in 50 patients with varus knee and also a femoral anterior osteotomy with four degree (S group) and seven degree (T group) flexion angles regarding the mechanical axis. We defined the final cutting plane as the farthest position that we could reach without making a notch and the precutting plane as two millimeters anterior from the final cutting plane. The simulated resection plane was rotated to produce external and internal rotation angles of 0°, three degrees, and five degrees relative to the surgical transepicondylar axis (SEA). We investigated medial and lateral portions of the femoral anterior cutting plane length ratio (M/L)., Results: When we cut parallel to SEA, M/L was 0.67±0.09 and 0.62±0.12 in the T and S groups, respectively. M/L was approximately 0.8 and 0.5 with five degree internal and external rotations, respectively (P<0.01). On comparing final cutting and precutting planes, there were no significant differences in M/L without five degree external rotation in the T group and no significant difference in any case in the S group (P>0.01)., Conclusions: The ideal M/L of the femoral anterior cutting plane was 0.62-0.67. M/L did not change with a precutting plane in almost all rotational patterns., (Copyright © 2017. Published by Elsevier B.V.)

Background: In TKA, we have used the "projected SEA", which is obtained by projecting the "true SEA" on the distal femoral cutting plane in clinical practice to determine the femoral component rotation. There are no reports examining the accuracy of the "projected SEA". In this study, we investigated the difference between the "true SEA" and "projected SEA"., Methods: The present study was a CT-based computer-simulated case series. We evaluated 34 knees without osteoarthritis changes. These patients were selected from the operative schedule prior to THA. We defined the "true SEA" on the 3D model and the "projected SEA" on the cutting plane parallel to the distal femoral axis obtained based on the "true SEA". We changed the cutting angles from 20° flexion to 20° extension, and from five degrees varus to five degrees valgus. We measured the "true SEA angle" and "projected SEA angle" regarding the posterior condylar axis (PCA)., Results: The mean "true SEA angle" was 3.04°±1.34° (0.6-5.0°). The mean "projected SEA angle" was 3.43°±1.58° at 20° flexion, 3.42°±1.56° at 0° flexion, 3.43°±1.52° at 20° extension, 3.39°±1.59° at five degrees valgus, and 3.39°±1.50° at five degrees varus. At each cutting angle, the "projected SEA angle" was significantly larger than the "true SEA angle" (p<0.001). There was no significant difference between any of the "projected SEA angles" (p>0.001)., Conclusions: We found that the true SEA and projected SEA do not differ significantly (0.39°±0.29° [range 0-1.0°])., (Copyright © 2017. Published by Elsevier B.V.)