Short knee radiographs can be inadequate for estimating TKA alignment in knees with bowing

Oh, Sung-Mok; Bin, Seong‐Il; Lee, Bum-Sik; Kim, Jong Min

doi:10.1186/s43019-019-0020-4

Cited by 9 publications

(4 citation statements)

References 31 publications

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“…Several trials to predict lower limb alignment using simple knee radiographs by linear regression analysis exist [ 10 , 20 ]. However, the results are not satisfactory, and to obtain satisfactory results, an X-ray image approximately 20 cm in length above and below the knee joint was required [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

Key-Point Detection Algorithm of Deep Learning Can Predict Lower Limb Alignment with Simple Knee Radiographs

Nam

Park

et al. 2023

JCM

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(1) Background: There have been many attempts to predict the weight-bearing line (WBL) ratio using simple knee radiographs. Using a convolutional neural network (CNN), we focused on predicting the WBL ratio quantitatively. (2) Methods: From March 2003 to December 2021, 2410 patients with 4790 knee AP radiographs were randomly selected using stratified random sampling. Our dataset was cropped by four points annotated by a specialist with a 10-pixel margin. The model predicted our interest points, which were both plateau points, i.e., starting WBL point and exit WBL point. The resulting value of the model was analyzed in two ways: pixel units and WBL error values. (3) Results: The mean accuracy (MA) was increased from around 0.5 using a 2-pixel unit to around 0.8 using 6 pixels in both the validation and the test sets. When the tibial plateau length was taken as 100%, the MA was increased from approximately 0.1, using 1%, to approximately 0.5, using 5% in both the validation and the test sets. (4) Conclusions: The DL-based key-point detection algorithm for predicting lower limb alignment through labeling using simple knee AP radiographs demonstrated comparable accuracy to that of the direct measurement using whole leg radiographs. Using this algorithm, the WBL ratio prediction with simple knee AP radiographs could be useful to diagnose lower limb alignment in osteoarthritis patients in primary care.

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Section: Discussionmentioning

confidence: 99%

Key-Point Detection Algorithm of Deep Learning Can Predict Lower Limb Alignment with Simple Knee Radiographs

Nam

Park

et al. 2023

JCM

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“…The radiographic study in two projections performed with SR are part of the standard preoperative study and periodic post-operative evaluation of this procedure. The SR plate is conventionally 30 by 40 cm in size, and it includes the lower femur and upper tibia 20 . This makes it impossible to know the mechanical axis of the limb, which is only possible by performing a LR, a CT, or using techniques such as navigation 21 or individualized templates 22 .…”

Section: Discussionmentioning

confidence: 99%

“…Of note in the literature is the publication of results of TKRs based only on SR where complications of other types can be seen but are never related to the axis of the limb [23][24][25][26][27] . Even in the most used clinical and functional questionnaires after TKR, SR is recommended as a support technique when post-operative limb alignment, rather than knee alignment, should be an essential piece of data for understanding the results and predicting potential complications 20 . The practice of LR certainly involves greater costs, specialized radiological equipment and a higher dose of radiation for the patient, but its absence weakens the evaluation of the technique and the outcomes of this procedure.…”

Section: Discussionmentioning

confidence: 99%

Is an x-ray of the knee sufficient to assess the alignment of the leg? A study of total joint replacement with surgical navigation.

Vaquero¹

2022

MRAJ

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Background: Understanding the femorotibial mechanical axis (FTMA) of the leg is a necessary requirement to assess the outcome of total knee replacement (TKR). Short radiographs, which only capture the knee joint and do not include the center of the femoral head and center of the ankle, only provide us the anatomical axis (FTAA), and not the FTMA. The purpose of this study was to compare the FTMA and FTAA before and after navigated TKR. Methods: In 130 patients undergoing surgery to implant the same TKR model, an x-ray was taken including the hip, knee and ankle. Images were analysed using a computer program that calculates the mechanical and anatomical axis of the femur, tibia and femorotibial joint. An image-free navigation system with femorotibial tensioned gap technique was used for the arthroplasty implantation. After surgery, a new long x-ray was taken, where the measurements indicated above were taken again. Results: Pre-operative x-rays showed a mean difference of 6º between FTAA and FTMA (p<0.001). No significant interaction was seen with patient height, but it was in patients with varus deformity and higher BMI (p=0.029); the greatest discrepancy between the anatomical and mechanical axis of the limb was found in individuals with excess weight. After TKR, the mean FTMA was modified to achieve a neutral axis (180° ±3°), as well as a concentration of the figures that showed great pre-procedure disparity, which was verified by the difference in the pre- and post-operative SD (11.85 versus 3.13). The maximum difference between FTAA and FTMA, which stood at 18º before decreased to 5.5º post-TKR. Conclusions: There is a major discrepancy between the FTAA and FTMA that increases when there is pre-operative varus deformity and in patients with excess weight. After TKR, the FTMA became concentrated, and the mean axis shifted towards the neutral axis. Performing x-rays that only include the knee is not useful for assessing the limb’s alignment prior to or after TKR.

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“…However, it is often the case that these angles change for no apparent reason. These angular changes are explained away as the result of technical errors arising from the distance from the cassette or X-ray beams, the parallax effect of the X-ray beams, and the position of the lower extremity [4][5][6][7][8][9][10][11][12][13]. Positioning the patient such that the patella faces forward, which is common while taking radiographs, may put the lower extremity in different rotational positions [5].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Position on Radiographic Angle Measurements of the Lower Extremities

Chung

Lee

Han

et al. 2022

BioMed Research International

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Purpose. Accurately measuring an angle on a lower extremity X-ray is essential for the diagnosis and treatment of knee osteoarthritis (KOA). However, the angle is often affected by position, especially with flexion contracture and rotation. To date, there have been no quantitative analyses examining the relationship between lower extremity angle and patient position and no studies targeting patients with deformities. The aim of this study is to quantify the effect of position on angle measurements in lower extremity X-rays and to compare the effect in patients with different deformities. Methods. Computed tomography (CT) data of 131 patients with knee pain were retrospectively analyzed. The subjects were categorized into the following groups: neutral (hip-knee-ankle angle (HKAA) between 175 and 185°), varus (HKAA less than 175°), valgus (HKAA more than 185°), and flexion (flexion contracture more than 10°). CT images were digitally reconstructed to anterior-posterior X-ray images using an average intensity projection algorithm. The process was then repeated while rotating the reconstruction plane from internal 9° to external 9°. In this manner, X-ray images were reconstructed in different rotational states. The following angles were measured from reconstructed X-ray images: HKAA, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and femoral valgus angle (FVA). The measurements were then compared according to the degree of rotation. Results. FVA significantly differed according to rotation in all groups ( P < 0.001 ), with a difference of 1.3° (±0.4°). HKAA significantly changed only in the flexion contracture group ( P < 0.001 ), which showed a difference of 1.0° (±0.7°). However, HKAA in the other groups, LDFA, and MPTA did not significantly differ depending on rotation. Conclusions. Radiographic measurement of FVA is subject to change according to rotation. HKAA significantly changed only in the flexion contracture group, so more care should be taken while obtaining X-rays of patients with flexion contracture.

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Short knee radiographs can be inadequate for estimating TKA alignment in knees with bowing

Cited by 9 publications

References 31 publications

Key-Point Detection Algorithm of Deep Learning Can Predict Lower Limb Alignment with Simple Knee Radiographs

Key-Point Detection Algorithm of Deep Learning Can Predict Lower Limb Alignment with Simple Knee Radiographs

Is an x-ray of the knee sufficient to assess the alignment of the leg? A study of total joint replacement with surgical navigation.

The Effect of Position on Radiographic Angle Measurements of the Lower Extremities

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