Due to great variability fixed HKS angle for alignment of the distal cut leads to a significant error in coronal TKA orientation

Lampart, Maurin; Behrend, Henrik; Moser, Lukas B.; Hirschmann, Michael T.

doi:10.1007/s00167-018-5041-0

Cited by 23 publications

(22 citation statements)

References 18 publications

(30 reference statements)

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“…Therefore, there is an urgent need for a convenient and effective method to measure HKA. Traditional HKA measurement methods [5][6][7] rely on the doctors to calculate the angle. No automatic measurement system has emerged yet.…”

Section: Introductionmentioning

confidence: 99%

Automated measurement of hip–knee–ankle angle on the unilateral lower limb X-rays using deep learning

et al. 2020

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Significant inherent extra-articular varus angulation is associated with abnormal postoperative hip-knee-ankle (HKA) angle. At present, HKA is manually measured by orthopedic surgeons and it increases the doctors' workload. To automatically determine HKA, a deep learning-based automated method for measuring HKA on the unilateral lower limb X-rays was developed and validated. This study retrospectively selected 398 double lower limbs X-rays during 2018 and 2020 from Jilin University Second Hospital. The images (n = 398) were cropped into unilateral lower limb images (n = 796). The deep neural network was used to segment the head of hip, the knee, and the ankle in the same image, respectively. Then, the mean square error of distance between each internal point of each organ and the organ's boundary was calculated. The point with the minimum mean square error was set as the central point of the organ. HKA was determined using the coordinates of three organs' central points according to the law of cosines. In a quantitative analysis, HKA was measured manually by three orthopedic surgeons with a high consistency (176.90 ° ± 12.18°, 176.95 ° ± 12.23°, 176.87 ° ± 12.25°) as evidenced by the Kandall's W of 0.999 (p < 0.001). Of note, the average measured HKA by them (176.90 ° ± 12.22°) served as the ground truth. The automatically measured HKA by the proposed method (176.41 ° ± 12.08°) was close to the ground truth, showing no significant difference. In addition, intraclass correlation coefficient (ICC) between them is 0.999 (p < 0.001). The average of difference between prediction and ground truth is 0.49°. The proposed method indicates a high feasibility and reliability in clinical practice.

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Section: Introductionmentioning

confidence: 99%

Automated measurement of hip–knee–ankle angle on the unilateral lower limb X-rays using deep learning

et al. 2020

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“…Interestingly, despite using a variable VCA, there were 15% outliers in group A, which may be due to the discrepancy between the plan and its execution. Lampart et al [ 21 ] prospectively collected computed tomography (CT) data from 1480 consecutive patients who underwent CT for 3D reconstruction before TKA and observed a variable femoral mechanical (FMA) angle. They concluded that due to greater variability of the FMA angle, the FMA angle seems more relevant than the hip-knee-shaft (HKS) angle in defining the strategy of realignment of the lower limb.…”

Section: Discussionmentioning

confidence: 99%

Achieving coronal plane alignment in total knee arthroplasty through modified preoperative planning based on long-leg radiographs: a prospective study

Singh

2021

J EXP ORTOP

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Purpose This prospective study was undertaken to examine whether the desired coronal plane alignment of limb and prosthetic components in total knee arthroplasty (TKA) could be achieved precisely using conventional jig-based methods by modifying the preoperative planning of bone resection utilizing long-leg radiographs (LLRs). Methods The study included consecutive 245 TKA procedures. Pre- and postoperative radiological variables, i.e., the mechanical axis (hip-knee-ankle [HKA] axis), mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle (MPTA), and their outliers were evaluated. Statistical analysis was performed using SPSS version 21.0. Results The mean postoperative HKA axis, mLDFA and MPTA was 179.80 ± 1.81° (p < 0.01; 95% CI: 8.09–9.67), 90.35 ± 1.54° (p < 0.01; 95% CI: 1.33–2.02), and 90.26 ± 1.25° (p < 0.01; 95% CI: 4.41–5.20), respectively. The postoperative HKA axis on the coronal plane was 180 ± 3° in 235 knees (95.92%, 4.08% outliers). Femoral and tibial components were implanted in an acceptable position, withing 90 ± 3° of the mechanical axis of the femur and tibia on the coronal plane in 238 (97.14%, 2.86% outliers) and 243 (99.18%, 0.8% outliers) knees, respectively. Conclusion Modified preoperative planning for TKA on LLRs is a reliable and consistent method to achieve the desired limb and component alignment on the coronal plane without adding financial or logistical costs. Level of evidence II

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“…A recent study evaluated 1,480 consecutive patients with hip-knee-shaft angles ranging from 2.5°-9°, confirming the insufficiency of the aforementioned correction to AP measurements in many cases. 30 Thus, despite the high correlation between AP and full-length radiographs, there is great potential for misinterpretation of true mechanical alignment when using measurements on standard AP radiographs as proxies.…”

Section: Discussionmentioning

confidence: 99%

True Mechanical Alignment is Found Only on Full-Limb and not on Standard Anteroposterior Radiographs

Graden

Dean

Kahat

et al. 2020

Arthroscopy, Sports Medicine, and Rehabilitation

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Purpose The purpose of this study was to compare alignment measured on standard anteroposterior (AP) radiographs versus full-length weight-bearing radiographs. Methods Patients were prospectively enrolled from June 2019 to August 2019 from a single orthopedic surgeon’s practice if they were ≥ 18 years of age, obtained both AP and full-length alignment radiographs and were capable of full weight-bearing with appropriate positioning. Patients were excluded if they were < 18 years of age, had previous knee arthroplasty, previous knee or hip osteotomy, were unable to bear full weight on both limbs, and if the patient’s body habitus precluded appropriate visualization of necessary landmarks on the radiographs. Tibiofemoral angles were measured on AP radiographs using 2 techniques (AP angles 1 and 2). Linear regression and paired t tests were used to compare measurements. The minimal clinically important difference was defined as < 2°. Results There were 120 patients (62 males, 58 females) with an average age of 45 ± 17 years who were enrolled. There were positive correlations between average alignment on full-length weight-bearing and AP radiographs for AP angle 1 ( r = 0.72) and AP angle 2 ( r = 0.76) measurement techniques ( P < .001). There was a significant difference in mean alignment between full-length weight-bearing and AP measurements (AP angle 1: 2.5° difference; AP angle 2: 4.4° difference; P < .001). Frequency distributions for the minimal clinically important difference between true mechanical alignment and AP views demonstrated that 46.7% of patients had ≥ 2° difference for AP angle 1, and 78.3% of patients had ≥ 2° difference for AP angle 2. Conclusion The average absolute difference in alignment measured between standard AP radiograph and full-length weight-bearing radiograph views was significant, with 46.7% to 78.3% of patients having a greater than 2° absolute difference between these 2 views. In cases where precise objective alignment measurement is necessary, full-length weight-bearing radiographs are recommended over standard AP radiographs for presurgical planning so as to reduce potential error in over- or underestimation of the true mechanical alignment. Study Design Prospective case-comparison; Level of evidence, 1.

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Due to great variability fixed HKS angle for alignment of the distal cut leads to a significant error in coronal TKA orientation

Cited by 23 publications

References 18 publications

Automated measurement of hip–knee–ankle angle on the unilateral lower limb X-rays using deep learning

Automated measurement of hip–knee–ankle angle on the unilateral lower limb X-rays using deep learning

Achieving coronal plane alignment in total knee arthroplasty through modified preoperative planning based on long-leg radiographs: a prospective study

True Mechanical Alignment is Found Only on Full-Limb and not on Standard Anteroposterior Radiographs

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