Relationship between tibio-fibular overlap ratio and lower limb torsion in an Asian population.

Forty-seven children with 70 clubfeet had computed tomography studies performed to determine the degree of femoral, tibial, and total limb torsion in both lower limbs. The total limb torsion angle (angle between the axis of the femoral neck and the axis of the ankle), which describes the relationship between femoral and tibial torsion, was used to evaluate the whole rotational deformity of the lower limb. The children were between the ages of 2 and 10 years (mean, 5 years) at the time of the computed tomography study. The mean femoral torsion was 25 degrees in the limbs with a clubfoot and 23 degrees in the contralateral limbs of patients with a unilateral clubfoot. The mean tibial torsion was 25 degrees in the limbs with a clubfoot and 24 degrees in the contralateral limb of patients with a unilateral clubfoot. The authors observed decreases of anterior femoral torsion corresponding to increases in age, consistent with the observations made by other authors of studies of children without clubfoot. External tibial torsion increased with age, with similar values in limbs with and without clubfoot. Ten limbs (nine with clubfoot, one without clubfoot) had femoral torsion greater than the means plus one standard deviation and 12 limbs (eight with clubfoot, four without clubfoot) had tibial torsion less than the means minus one standard deviation. The authors found four limbs (all with clubfoot) in three patients with lower than the mean minus one standard deviation of the total limb torsion angle (intoeing). Overall, there was no appreciable difference in the amount of femoral or tibial torsion in limbs with and without a clubfoot.

The prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT. We retrospectively evaluated symptomatic patients with FAI or hip dysplasia with CT scans performed between September 2011 and September 2016. A total of 261 hips (174 patients) had a measurement of FT and TT. Their mean age was 31 years (SD 9), and 63% were female (165 hips). Patients were compared to an asymptomatic control group (48 hips, 27 patients) who had CT scans including femur and tibia available for analysis, which had been acquired for nonorthopaedic reasons. Comparisons were conducted using analysis of variance with Bonferroni correction. In the overall study group, abnormal FT was present in 62% (163 hips). Abnormal TT was present in 42% (109 hips). Normal FT combined with normal TT was present in 21% (55 hips). The most frequent abnormal combination was increased FT combined with normal TT of 32% (84 hips). In the hip dysplasia group, 21% (11 hips) had increased FT combined with increased TT. The prevalence of abnormal FT varied significantly among the subgroups (p < 0.001). We found a significantly higher mean FT for hip dysplasia (31°; SD 15)° and valgus hips (42° (SD 12°)) compared with the control group (22° (SD 8°)). We found a significantly higher mean TT for hips with cam-type-FAI (34° (SD 6°)) and hip dysplasia (35° (SD 9°)) compared with the control group (28° (SD 8°)) (p < 0.001). Patients with FAI had a high prevalence of combined abnormalities of FT and TT. For hip dysplasia, we found a significantly higher mean FT and TT, while 21% of patients (11 hips) had combined increased TT and increased FT (combined torsional malalignment). This is important when planning hip preserving surgery such as periacetabular osteomy and femoral derotation osteotomy. Cite this article: Bone Joint J 2020;102-B(12):1636-1645.

The EOS imaging system is an advanced piece of equipment for full-body imaging, but its reliability and reproducibility should be further verified. A prospective study was conducted including 18 adult volunteers (36 lower extremities) (24±2 years old). Femoral and tibial torsion were measured by both EOS imaging and three-dimensional computed tomography (3D CT) reconstruction. Bland-Altman plots were performed to evaluate the difference between femoral and tibial torsion measurements obtained by these two methods. The intraclass correlation coefficient (ICC) was used to evaluate intrareader agreement. The mean difference between the two methods was 3° (range, -9° to 4°) for femoral torsion, 0° (range, -6° to 6°) for tibial torsion and 0° (range, -4° to 5°) for femorotibial torsion. No statistically significant difference between the measurements of the two methods was detected by Bland-Altman plots. With the exception of one measurement of femoral torsion, one measurement of tibial torsion and one measurement of femorotibial torsion, all EOS imaging measurements were within the 95% limits of agreement (the mean ± 1.96 SD). Intrareader agreement was statistically significant (P<0.001) for all measurements, with high ICCs. For EOS imaging, the ICC was 0.92 for the femoral measurement, 0.92 for the tibial measurement and 0.918 for the femorotibial measurement; the corresponding values for CT were 0.950, 0.927 and 0.889. There was good agreement between EOS imaging based and 3D CT reconstruction based technique in measuring femoral, tibial and femorotibial torsion; and good reliability and reproducibility of EOS Imaging in measuring femoral, tibial and femorotibial torsion was also verified.

BackgroundTo investigate the relationship between femoral or tibial torsion and hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), or mechanical medial proximal tibial angle (mMPTA) in patients with medial knee osteoarthritis (OA).MethodsA total of 75 knees were enrolled. Femoral and tibial torsions were measured by superimposing the axial planes of computed tomography images. The relationship between femoral or tibial torsion and HKA, mLDFA, or mMPTA on radiographs was examined.ResultsThe mean femoral torsion was 12.2 ± 8.5° internally; femoral internal and external torsions were observed in 70 and 5 knees, respectively. The mean tibial external torsion was 18.0 ± 7.4° externally; tibial external torsion was observed in all 75 knees. Femoral internal and tibial external torsions increased with lower mMPTA (r = 0.33, P = 0.003; r = − 0.32, P = 0.005, respectively) but were not related to HKA or mLDFA.ConclusionFemoral and tibial torsions were correlated with varus inclination of the proximal tibia in patients with medial knee OA.

To evaluate in children the agreement between femoral and tibial torsion measurements obtained with low-dose biplanar radiography (LDBR) and CT, and to study dose reduction ratio between these two techniques both in vitro and in vivo. Thirty children with lower limb torsion abnormalities were included in a prospective study. Biplanar radiographs and CTs were performed for measurements of lower limb torsion on each patient. Values were compared using Bland-Altman plots. Interreader and intrareader agreements were evaluated by intraclass correlation coefficients. Comparative dosimetric study was performed using an ionization chamber in a tissue-equivalent phantom, and with thermoluminescent dosimeters in 5 patients. Average differences between CT and LDBR measurements were -0.1° ±1.1 for femoral torsion and -0.7° ±1.4 for tibial torsion. Interreader agreement for LDBR measurements was very good for both femoral torsion (FT) (0.81) and tibial torsion (TT) (0.87). Intrareader agreement was excellent for FT (0.97) and TT (0.89). The ratio between CT scan dose and LDBR dose was 22 in vitro (absorbed dose) and 32 in vivo (skin dose). Lower limb torsion measurements obtained with LDBR are comparable to CT measurements in children and adolescents, with a considerably reduced radiation dose. • LDBR and CT lower-limb torsion measurements are comparable in children and adolescents. • LDBR considerably reduced radiation dose necessary for lower-limb torsion measurements. • LDBR can be used for evaluation of lower limb-torsion in orthopaediatric patients.

Several anatomic risk factors associated with patellofemoral disorders have been described. The purpose of this study was to analyze the relationship between bony parameters commonly used to analyze and define patellofemoral malalignment. Patients with patellofemoral disorders presenting between 2016 and 2018 who underwent a standardized radiographic workup including conventional radiographs, weight bearing full-leg radiographs, magnetic resonance imaging (MRI) of the knee, and torsional analysis using hip-knee-ankle MRI were initially included. Patients with a history of lower extremity fracture and a history of surgical procedures affecting bony alignment or partial/total arthroplasty were subsequently excluded. Radiographs and MRI of all included patients were analyzed by four independent observers. Parameters of interest were: femoral torsion, tibial torsion, trochlear dysplasia, tibial tuberosity-trochlear groove (TT-TG) distance, and frontal mechanical axis. All parameters were compared between patients with low grade and high grade trochlear dysplasia as well as between female and male patients. Correlation of continuous variables was assessed with the Pearson correlation coefficient. A binary logistic regression model was used for the calculation of odds ratio between different parameters. Interclass correlation coefficients (ICC) were calculated to determine the interobserver reproducibility. A total of 151 patients could be included for detailed analysis. Group comparison revealed that patients with high grade trochlear dysplasia showed significantly higher values for femoral torsion (low grade: 9.8° ± 11.0°, high grade: 16.8° ± 11.5°; p < 0.001) and significantly higher values for TT-TG distance (low grade: 19.0mm ± 5.0mm, high grade: 21.9mm ± 5.4mm; p = 0.002). No significant difference was found for age, tibial torsion, and frontal mechanical axis. With regard to gender, female patients had higher values for femoral torsion (female: 15.6° ± 11.3°, male: 11.0° ± 12.7°; p = 0.044). The correlation analysis found significant correlation between femoral torsion and tibial torsion (r = 0.244, p = 0.003), femoral torsion and TT-TG distance (r = 0.328, p < 0.001), femoral torsion and frontal mechanical axis (r = 0.291, p < 0.001), and tibial torsion and TT-TG distance (r = 0.182, p = 0.026). Bony malalignment in patients with patellofemoral disorder is a complex problem given the significant correlation between femoral and tibial torsion, trochlear dysplasia, TT-TG distance, and frontal mechanical axis. Advanced imaging to analyze rotational and frontal plane alignment is recommended in patients with trochlear dysplasia and/or increased TT-TG on standard radiographs and knee MRI. Understanding of the bony pathology in patellofemoral disorders is key to improve the therapeutic and surgical decision. III, retrospective cohort study.

Torsion of the lower extremities has been suggested to be a predisposing factor for patellar instability. However, no clear torsional factors have been clarified. This study aimed to elucidate the rotational geometry of the lower limb through segmental analysis in patients with patellar instability. Eighty-three patients with patellar instability were included. Computed tomography of the lower limb was acquired. Femoral and tibial torsion were measured in different segments. Femoral and tibial torsion in each segment was compared between the high- and normal-torsion groups to investigate which segment contributes the most. All segments of femoral and tibial torsion except proximal femoral torsion showed significant differences between the high- and normal-torsion groups. The average proximal femoral torsion was 1.9° ± 7.1°, indicating that there was only slight torsion in the segment of the femoral neck. The angle between the femoral neck and the foot orientation in the normal-torsion, high-torsion tibial, and combined high-torsion femoral and tibial groups was 89.1° ± 12.0°, 81.3° ± 9.4°, and 98.2° ± 11.7°, respectively (p < 0.001), which suggested that the femoral neck remained nearly perpendicular to the foot orientation in the normal-torsion group. Shaft and distal femoral torsion contributed the most to total femoral torsion. For tibial torsion, from distal to proximal, internal torsion of both the proximal and distal segments contributed to the high torsion. There was no significant difference between distal femoral torsion and proximal tibial torsion, which suggested that, rather than the distal femur rotating internally on its own, the distal femur and the proximal tibia simultaneously rotated internally. In patients with patellar instability, torsional deformity occurs along the length of the tibia and in the shaft and distal segments of the femur. The comprehensive embodiment of lower-extremity malrotation is an internal rotation deformity of the knee. This study elucidated the rotational geometry of the lower limb through a detailed segmental analysis in patients with patellar instability. It could serve as a theoretical basis for choosing a derotational osteotomy site and may be a reference for additional clinical research.

The aim of this study was to investigate the association of femoral (FT), tibial (TT), and knee torsion (KT) on the patella tilt (PT), the axial engagement index (AEI), and the tibial tuberosity-trochlear groove distance (TTTG). Femoral torsion, tibial torsion, knee torsion, patella tilt, the axial engagement index, the TTTG, and trochlear dysplasia were retrospectively evaluated on 59 patients suffering from recurrent patella instability or anterior knee pain with 118 torsional lower limb magnetic resonance imaging studies. FT and TT did not show any significant associations with TTTG, PT, and AEI (n.s.). KT was significantly associated with a higher TTTG, higher PT, and lower AEI (all, p < 0.001). Higher grade trochlear dysplasia was associated with a higher PT and lower AEI (both, p < 0.001). The Dejour classification showed no significant association with FT, TT, KT, and TTTG (n.s.). All measurement parameters showed an excellent interrater agreement (ICC 0.89-0.97). Static patella tilt and patellofemoral axial engagement in knee extension are mainly influenced by knee torsion, TTTG, and trochlear dysplasia but not by femoral or tibial torsion. These findings help to understand the underlying reasons for the patella position in knee extensions in CT and MRI investigations in patients suffering from patella instability and patellofemoral pain syndrome. III.

Purpose:To analyze the torsion of the lower extremities in a healthy cohort and to determine the contribution of different segments of the femur and tibia to the torsion of both bones.Methods:In this cross-sectional study, 32 patients with nonjoint or bone-related symptoms were analyzed by CT angiography. Lower-limb torsion, femoral torsion, proximal femoral torsion, femoral shaft torsion, distal femoral torsion, tibial torsion, proximal tibial torsion, and distal tibial torsion were measured.Results:The median total limb torsion was 25° external torsion, with the median femoral torsion being −9° and the median tibial torsion 30°. Both femoral metaphyses had internal torsion, with the internal torsion of the proximal metaphysis being approximately three times greater than that of the distal femoral metaphysis. The shaft was found to compensate with an external torsion of approximately two-thirds of the internal torsion of both femoral metaphyses. The proximal metaphysis of the tibia accounted for approximately one-third of the external torsion, with the segment from the distal to the tibial tubercle accounting for the remaining two-thirds of the tibial torsion.Conclusions:The diaphysis and distal metaphysis are the major contributors to external torsion of the tibia, whereas the proximal metaphysis is the major contributor to the internal torsion of the femur.

The results of tibial osteotomy used to treat osteoarthritis of the medial compartment of the knee deteriorate over time even when the initial correction is optimal. Studies have shown that tibial and femoral torsion and the femorotibial index (tibial torsion minus femoral torsion) contribute, together with coronal malalignment, to the development of single-compartment knee osteoarthritis. The objective of our study was to evaluate the impact of femoral and tibial torsion and of coronal realignment on the long-term clinical and radiographic outcomes of valgus tibial osteotomy. A function score was calculated for sixty-eight patients at a mean of thirteen years after the osteotomy. Anteroposterior single-leg-stance radiographs were used to evaluate loss of the femorotibial joint space. Goniometry was used to measure coronal malalignment preoperatively, at one year, and at the time of the last follow-up, and postoperative computed tomography was performed to measure femoral anteversion and tibial torsion and to calculate the femorotibial index. We looked for associations linking body mass index, initial loss of joint space, coronal malalignment, femoral and tibial torsion, the femorotibial index, and functional outcomes. Worse outcomes were associated with changes in coronal alignment (>/=2 degrees ) over time, which were associated with deterioration of the femorotibial space. Femoral anteversion was significantly greater in patients in whom valgus increased over time than in those in whom valgus decreased over time. Stability of coronal alignment seemed to be dependent on a linear relationship between the femorotibial index and the degree of postoperative realignment. A body mass index of >25 kg/m(2) was associated with a long-term loss of coronal realignment. Preoperative loss of the medial femorotibial joint space, coronal alignment at one year, and age were not associated with secondary malalignment or functional outcomes. Long-term success of a valgus tibial osteotomy is related to the stability over time of the postoperative coronal realignment. Therefore, the results of our study suggest that modifying the realignment according to the extent of femoral anteversion may improve long-term outcomes.

Background: The results of tibial osteotomy used to treat osteoarthritis of the medial compartment of the knee deteriorate over time even when the initial correction is optimal. Studies have shown that tibial and femoral torsion and the femorotibial index (tibial torsion minus femoral torsion) contribute, together with coronal malalignment, to the development of single-compartment knee osteoarthritis. The objective of our study was to evaluate the impact of femoral and tibial torsion and of coronal realignment on the long-term clinical and radiographic outcomes of valgus tibial osteotomy. Methods: A function score was calculated for sixty-eight patients at a mean of thirteen years after the osteotomy. Anteroposterior single-leg-stance radiographs were used to evaluate loss of the femorotibial joint space. Goniometry was used to measure coronal malalignment preoperatively, at one year, and at the time of the last follow-up, and postoperative computed tomography was performed to measure femoral anteversion and tibial torsion and to calculate the femorotibial index. We looked for associations linking body mass index, initial loss of joint space, coronal malalignment, femoral and tibial torsion, the femorotibial index, and functional outcomes. Results: Worse outcomes were associated with changes in coronal alignment (≥2°) over time, which were associated with deterioration of the femorotibial space. Femoral anteversion was significantly greater in patients in whom valgus increased over time than in those in whom valgus decreased over time. Stability of coronal alignment seemed to be dependent on a linear relationship between the femorotibial index and the degree of postoperative realignment. A body mass index of >25 kg/m2 was associated with a long-term loss of coronal realignment. Preoperative loss of the medial femorotibial joint space, coronal alignment at one year, and age were not associated with secondary malalignment or functional outcomes. Conclusions: Long-term success of a valgus tibial osteotomy is related to the stability over time of the postoperative coronal realignment. Therefore, the results of our study suggest that modifying the realignment according to the extent of femoral anteversion may improve long-term outcomes. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

Background: Increased femoral torsion (FT) or tibial torsion (TT) has been suggested to be a potential risk factor for recurrent patellofemoral instability. However, the influence of increased FT or TT on the postoperative clinical outcomes of recurrent patellofemoral instability has rarely been investigated. Purpose: To assess the effect of increased FT or TT on postoperative results in patients with recurrent patellofemoral instability after combined medial patellofemoral ligament reconstruction (MPFLR) and tibial tubercle transfer, along with the influence of other risk factors. Study Design: Cohort study; Level of evidence, 3. Methods: Out of 91 patients, the study’s analyses included 86 patients with recurrent patellofemoral instability who were treated with MPFLR and tibial tubercle transfer and enrolled between April 2020 and January 2021. FT and TT were assessed using preoperative computed tomography images. According to the torsion value of FT or TT, patients were categorized into 3 groups for each of FT and TT: group A (<20°), group B (20°-30°), and group C (>30°). Patellar height, femoral trochlear dysplasia, and the tibial tuberosity–trochlear groove (TT-TG) distance were also assessed. Patient-reported outcome scores (Tegner, Kujala, International Knee Documentation Committee [IKDC], Lysholm, and Knee injury and Osteoarthritis Outcome Score [KOOS]) were evaluated pre- and postoperatively. Clinical failure of MPFLR was recorded. Subgroup analysis was conducted to evaluate the effect of increased FT or TT on the postoperative outcomes. Results: A total of 86 patients were enrolled with a median follow-up time of 25 months. At the final follow-up, all functional scores improved significantly. Patella alta, high-grade trochlear dysplasia, and increased TT-TG distance did not have any significant effect on the postoperative functional scores. Regarding FT, subgroup analysis indicated that all functional scores of group C were lower than those of groups A and B except the KOOS knee-related Quality of Life score. For TT, group C had lower scores than group A for all functional outcomes except Tegner and KOOS Quality of Life and lower scores than group B for Kujala, IKDC, KOOS (Symptoms and Sport and Recreation subscales), Tegner, and Lysholm scores. The comparison between group A and group B, whether for FT or TT, revealed no significant differences. Conclusion: For patients with recurrent patellofemoral instability, increased lower extremity torsion (FT or TT >30°) was associated with inferior postoperative clinical outcomes after combined MPFLR and tibial tubercle transfer.

Measuring femoral and rotational alignment: EOS system versus computed tomography

Malalignment of the lower extremity can affect one, two or all three anatomic planes. We hypothesized an influence between the malalignment of the coronal and axial planes. A total of 356 lower extremities of 226 patients were included. Femoral and tibial torsion were assessed in computer tomographic scans while frontal plane alignment was measured in long-leg standing radiographs. The mechanical angles were for knee phenotyping according to the coronal plane alignment of the knee classification. The correlation between the coronal alignment and torsional profile was analyzed. The population was divided into three groups according to leg alignment (valgus, neutral, varus) and gender. As the coronal alignment changed from valgus to varus the tibial external torsion increased (r = 0.35; p < 0.001). Femoral internal torsion increased as well but only in the male subgroup (r = -0.34; p < 0.001). Both femoral internal torsion and tibial external torsion increased with higher mechanical lateral distal femoral angle (mLDFA) but were not related to mechanical medial proximal tibial angle. A distinct pattern of results concerning knee phenotypes in relation to femoral and tibial torsion was found. Tibial torsion correlated with increasing varus alignment while both femoral and tibial torsion correlated with higher mLDFA, but the correlations were weak. Therefore, the coronal alignment does not enable to predict the degree of femoral and tibial torsion. This study demonstrates that an individual approach to each patient with lower limb malalignment is unavoidable. Level III.

Recurrent patellar dislocation in children and adolescents is a multifactorial condition associated with anatomic risk factors such as patella alta, trochlear dysplasia, and torsional deformities of the lower limb. Although medial patellofemoral ligament reconstruction (MPFLR) is the standard approach, undetected torsional abnormalities may compromise outcomes. While computed tomography (CT) offers precise femoral torsion (FT) and tibial torsion (TT) evaluation, its widespread use is constrained by cost and radiation exposure. To evaluate whether conventional radiographic parameters can predict excessive lower limb torsion in patients undergoing MPFLR. Cohort Study (Diagnosis); Level of evidence, 3. The authors retrospectively analyzed 104 knees (70 patients) evaluated using CT for FT, TT, and combined torsion (FT+TT) between December 2016 and December 2023. Radiographic measures included the Caton-Deschamps index, congruence angle, sulcus angle, and patellar tilt angle. FT and TT were categorized as <20°, 20° to 30°, or >30°, and FT+TT as <40°, 40° to 50°, or >50°. Receiver operating characteristic (ROC) analysis and multivariate regression were used to assess the diagnostic performance of radiographic variables. The patellar tilt angle was significantly associated with FT (r = 0.24; P = .015) and FT+TT (r = 0.27; P = .009). ROC analysis showed the highest predictive accuracy for patellar tilt angle, with an area under the curve of 0.629 for FT >20°, 0.653 for FT >30°, and 0.665 for FT+TT >50°. A threshold of 20° was identified across categories. Body mass index (β = -0.461; P = .019) and patellar tilt angle (β = 0.222; P = .021) were independent predictors of FT (adjusted R 2 = 0.102). This study showed that although patellar tilt angle demonstrated the highest predictive value among evaluated parameters, its diagnostic accuracy was limited and insufficient to replace cross-sectional imaging. Comprehensive preoperative evaluation of lower limb torsion remains critical for minimizing residual instability and improving outcomes after MPFLR.