Limb length discrepancy after total knee arthroplasty: Unilateral versus bilateral, a comparative study at tertiary centre

Sabir, Aamir Bin; Faizan, Mohd; Ishtiaq, Md.; Jilani, Latif Zafar; Ahmed, Sohail; Shaan, Ziaul Hoda

doi:10.1016/j.jcot.2020.06.041

Cited by 5 publications

(12 citation statements)

References 16 publications

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“…Though these authors [ 2 ] state that LLD is significant, it may not be clinically important if patients do not appreciate a difference in their limb length. Moreover, a study states that patients only perceive a leg length change of 2 cm or more [ 12 ], suggesting that the majority of patients in our study would not perceive a difference in their limb length after surgery. Our findings suggest that limb lengthening occurs frequently after TKA, but not to a statistically significant extent.…”

Section: Discussionmentioning

confidence: 82%

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

Fang

McAlpine

Gustin

et al. 2021

Advances in Orthopedics

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Introduction. Expectations for limb length differences after TKA are important for patient perception and outcomes. Limb length discrepancies may occur due to postoperative leg length increases, which can lead to decreased patient functionality and satisfaction and even possible litigation. The purpose of this study is to examine the frequency and extent of limb lengthening among various preoperative deformities and between two different implant systems. Methods. Preoperative and postoperative full-length standing radiographs were obtained between August 2018 and August 2019 to measure mechanical axis and limb length of operative limbs. Demographic information such as age, sex, and BMI was also collected. Patients were grouped into categories for pre- and postoperative subgroup analysis: valgus, varus, customized implant, and conventional implant. Regression analysis was performed to evaluate significant relationships. Results. Of the 121 primary TKAs analyzed, 62% of the knees showed an increase in limb length after TKA, with an average lengthening of 5.32 mm. Preoperative varus alignment was associated with a mean lengthening of 3.14 mm, while preoperative valgus alignment was associated with a mean lengthening of 16.2 mm. Overall, there were no statistically significant differences in limb lengths pre- and postoperatively ( p = 0.23) and no significant changes in limb length for any subgroup. Further, no variables were associated with limb length changes ( p = 0.49), including the use of customized implants ( p = 0.2). Conclusions. Limb lengthening after TKA is common and, on average, occurs more significantly in valgus knees. No significant difference in limb lengthening could be demonstrated using customized over conventional implants. Preoperative counseling is important to manage patient expectations.

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Section: Discussionmentioning

confidence: 82%

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

Fang

McAlpine

Gustin

et al. 2021

Advances in Orthopedics

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“…predicted a limb length change of 4 mm for each 10-degree correction in HKA angle [ 10 ]. Accordingly, the more limb length change is expected in the developing and underdeveloped countries where the patients often visit at an advanced stage with extremes of deformity [ 14 ].…”

Section: Discussionmentioning

confidence: 99%

“…Sabir et al . warned that unilateral TKA in bilaterally-affected OA knee might end up with significant LLD causing patient dissatisfaction and poor functional outcome [ 14 ]. In agreement with previous literature, this study also found that the functional outcome was adversely affected when LLD exceeded 10 mm.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Only a few studies in the literature evaluated LLD after TKA [ 5 , 6 , 10 , 14 , 15 , 17 – 23 ]. While the western literature reported minimal LLD (< 5.5 mm) that has no clinical relevance [ 6 , 18 – 21 , 23 ], others have reported substantial limb length discrepancy (≥ 10 mm) following unilateral TKA [ 10 , 14 , 15 , 17 ]. The LLD issue is more alarming in India and few other Asian countries because of the late presentation, advanced disease with bone defect, ligamentous laxity and proceeding for unilateral TKA despite severe bilateral disease.…”

Section: Introductionmentioning

confidence: 99%

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Impact of limb length discrepancy on functional outcome in total knee arthroplasty patients: a prospective cohort study

et al. 2022

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Background Limb length alteration following total knee arthroplasty (TKA) has been under-reported. Few studies have shown a significant association between limb length discrepancy (LLD) and poor functional outcome. This prospective study evaluated the impact of radiographic and perceived LLD on functional outcome in TKA. The variables affecting LLD were also evaluated. Methods The preoperative and postoperative limb lengths of TKA patients (112 knees, 81 patients, KL grade ≥ 3) were measured in full-length digital radiographs. The Hip-Knee-Ankle (HKA) angles were also measured. The functional outcome (Western Ontario and McMaster Universities Arthritis Index) and perception about LLD were evaluated after six months. Results The mean preoperative radiographic LLD in the unilateral and bilateral TKA groups was 0.75 cm ± 0.60 cm and 0.58 cm ± 0.52 cm (P = 0.197), respectively. Similarly, postoperative LLD was 0.76 cm ± 0.85 cm in the unilateral group and was 0.59 cm ± 0.92 cm (P = 0.402) in the bilateral group. Only 19.7% of patients had postoperative radiographic LLD of ≥ 10 mm, and 80.2% of patients had LLD of < 10 mm. The functional outcome was significantly affected when LLD exceeded 10 mm (correlation coefficient 0.54, P < 0.001). Linear regression analysis revealed no significant effects of age, sex, height, weight, BMI, preoperative LLD and difference in deformity between the limbs on postoperative LLD. 34.5% of patients perceived LLD in the preoperative period, which decreased to 3.7% in the postoperative period. Perceived LLD did not correlate to radiographic LLD and functional outcome. Conclusions There is no significant difference in radiographic LLD between unilateral and bilateral TKA. The functional outcome is adversely affected by radiographic LLD of ≥ 10 mm. Age, sex, BMI, preoperative LLD and difference in deformity angle do not affect the LLD. About one-third of patients perceive LLD in the preoperative period, which improves significantly after TKA. Levels of evidence II.

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Automated measurement of leg length discrepancy from infancy to adolescence based on cascaded LLDNet and comprehensive assessment

Zheng¹,

Liu²,

Tong³

et al. 2023

Quant Imaging Med Surg

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Background: Deep learning (DL) has been suggested for the automated measurement of leg length discrepancy (LLD) on radiographs, which could free up time for pediatric radiologists to focus on valueadding duties. The purpose of our study was to develop a unified solution using DL for both automated LLD measurements and comprehensive assessments in a large and comprehensive radiographic dataset covering children at all stages, from infancy to adolescence, and with a wide range of diagnoses. Methods:The bilateral femurs and tibias were segmented by a cascaded convolutional neural network (CNN), referred to as LLDNet. Each LLDNet was conducted through use of residual blocks to learn more abundant features, a residual convolutional block attention module (Res-CBAM) to integrate both spatial and channel attention mechanisms, and an attention gate structure to alleviate the semantic gap. The leg length was calculated by localizing anatomical landmarks and computing the distances between them. A comprehensive assessment based on 9 indices (5 similarity indices and 4 stability indices) and the paired Wilcoxon signed-rank test was undertaken to demonstrate the superiority of the cascaded LLDNet for segmenting pediatric legs through comparison with alternative DL models, including ResUNet, TransUNet, and the single LLDNet. Furthermore, the consistency between the ground truth and the DL-calculated measurements of leg length was also comprehensively evaluated, based on 5 indices and a Bland-Altman analysis. The sensitivity and specificity of LLD >5 mm were also calculated.Results: A total of 976 children were identified (0-19 years old; male/female 522/454; 520 children between 0 and 2 years, 456 children older than 2 years, 4 children excluded). Experiments demonstrated that the proposed cascaded LLDNet achieved the best pediatric leg segmentation in both similarity indices (0.5-1% increase; P<0.05) and stability indices (13-47% percentage decrease; P<0.05) compared with the alternative DL methods. A high consistency of LLD measurements between DL and the ground truth was also observed using Bland-Altman analysis [Pearson correlation coefficient (PCC) =0.94; mean bias =0.003 cm]. The sensitivity and specificity established for LLD >5 mm were 0.792 and 0.962, respectively, while those for LLD >10 mm were 0.938 and 0.992, respectively. Conclusions:The cascaded LLDNet was able to achieve promising pediatric leg segmentation and LLD measurement on radiography. A comprehensive assessment in terms of similarity, stability, and measurement consistency is essential in computer-aided LLD measurement of pediatric patients.

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Limb length discrepancy after total knee arthroplasty: Unilateral versus bilateral, a comparative study at tertiary centre

Cited by 5 publications

References 16 publications

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

Impact of limb length discrepancy on functional outcome in total knee arthroplasty patients: a prospective cohort study

Automated measurement of leg length discrepancy from infancy to adolescence based on cascaded LLDNet and comprehensive assessment

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