Varus-valgus Malalignment Research Articles

Description of new sign of integral (∫) for rotational deformity of distal femur.

Femur shaft fractures commonly occur due to high velocity trauma and most of them are fixed with nailing. Malrotation is common after fixation. A rotational malalignmentmore than 30° is a deformity which requires correction. Various techniques described for rotational deformities are: the 'cable techniques' for the determination of varus-valgus malalignment; the 'hyperextension test', 'radiographic recurvatum sign', 'tibial plateau sign', and 'meterstick technique' for length analysis; and the 'hip rotation test', 'lesser trochanter shape sign', 'cortical step sign', and 'diameter difference sign' for rotational analysis. We describe integration sign at the medial or lateral aspect of notch of femur in fixed internal or external rotation due to condensation of trabeculae. This is a prospective observational study. Informed consent was taken, and this study was approved by institutional review board. C arm imaging study of 50 knees was done at our institution in which rotational profile of distal femur was analyzed In 3 different views -AP , Internal and external rotation views. The rotation views were taken sequentially and each observer was asked to identify the sign at its appearance and at rotation when it was best seen. All the observers were asked to draw the sign on linear line diagram of distal femur. The data was analysed statistically. Sign of integral (∫) for rotational deformity was seen at Mean external rotation of 22±1.71 with a range of 19 degree to 25 degree and Mean internal rotation of 15.78±1.21 with a range of 14 degree to 18 degree. The integration sign can be used as intraoperative C arm sign to understand the rotational deformity of distal fragment of femur. This helps the surgeon to understand the alignment and revise if needed intraoperatively. If combined with position of lesser trochanter, this will give alignment for both proximal as well as distal fragment of femur.

Tibial tray rotation and posterior slope increase risk for outliers in coronal alignment.

The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation. We constructed a computer model of knee arthroplasty and used a virtual cutting guide to cut the tibia at 90° to the coronal plane. The virtual guide was rotated axially (15° medial to 15° lateral) and with posterior slopes (0° to 7°). To assess the effect of axial malrotation, we measured the coronal plane alignment of a tibial tray that was axially rotated (25° internal to 15° external), as viewed on a standard anteroposterior (AP) radiograph. Axial rotation of the cutting guide induced a varus-valgus malalignment up to 1.8° (for 15° of axial rotation combined with 7° of posterior slope). Axial malrotation of tibial tray induced a substantially higher risk of coronal plane malalignment ranging from 1.9° valgus with 15° external rotation, to over 3° varus with 25° of internal rotation. Coronal alignment of the tibial cut changed by 0.07° per degree of axial rotation and 0.22° per degree of posterior slope (linear regression, R2 > 0.99). While the effect of axial malalignment has been studied, the impact on coronal alignment is not known. Our results indicate that the direction of the cutting guide and malalignment in axial rotation alter coronal plane alignment and can increase the incidence of outliers. Cite this article: Bone Joint J 2020;102-B(6 Supple A):43-48.

Wearable inertial sensors and pressure MAT detect risk factors associated with ACL graft failure that are not possible with traditional return to sport assessments

IntroductionAnterior cruciate ligament reconstruction (ACLR) is associated with poor return to sport and high graft re-rupture rates. This study explored the use of a wearable inertial sensor (ViMove) that incorporates...

Coronal Knee Malalignment in Young Adults and Its Link to Body Measures.

Our aim was to report the prevalence of knee varus-valgus malalignment (KVVM) and its association with body mass index (BMI) and body height in a healthy and fit young adult population. Information on the disability codes associated with KVVM according to the Regulations of Medical Fitness Determination was retrieved from a medical database containing records of 17-year-old males and females before their recruitment into mandatory military service. Logistic regression models assessed the association between the BMI and body height to KVVM. The study cohort included 821,381 subjects (460,674 males and 360,707 females). The prevalence of KVVM was 0.9% in males and 0.6% for females. Under/overweight subjects were associated with higher prevalence of KVVM. The odds ratios (ORs) had a "J" curve pattern, increasing for underweight males and females, and even more so for above-normal BMIs (for obese males and for both overweight and obese females). The strongest association was between obese females and KVVM: an obese female had an OR of 22.864 (confidence interval [CI] = 20.683-25.725, p < 0.001) to have KVVM and an obese male had an OR of 4.483 (CI = 4.158-4.833 p < 0.001). When the BMI was analyzed as a continuous variable, each increase in one BMI unit was associated with an increase in OR of 7.6% for males and 24.1% for females. There is a strong association between BMI and KVVM in both underweight and overweight young adults. KVVM is more common in males, but most strongly associated with overweight and obese females.This is a Level III, case-control study.

Increases in tibial force imbalance but not changes in tibiofemoral laxities are caused by varus-valgus malalignment of the femoral component in kinematically aligned TKA.

The purposes of this study were to quantify the increase in tibial force imbalance (i.e. magnitude of difference between medial and lateral tibial forces)and changes in laxities caused by 2° and 4° of varus-valgus (V-V) malalignment of the femoral component in kinematically aligned total knee arthroplasty (TKA) and use the results to detemine sensitivities to errors in making the distal femoral resections. Because V-V malalignment would introduce the greatest changes in the alignment of the articular surfaces at 0° flexion, the hypotheses were that the greatest increases in tibial force imbalance would occur at 0° flexion, that primarily V-V laxity would significantly change at this flexion angle, and that the tibial force imbalance would increaseand laxities would change in proportion to the degree of V-V malalignment. Kinematically aligned TKA was performed on ten human cadaveric knee specimens using disposable manual instruments without soft tissue release. One 3D-printed reference femoral component, with unmodified geometry, was aligned to restore the native distal and posterior femoral joint lines. Four 3D-printed femoral components, with modified geometry, introduced V-V malalignments of 2° and 4° from the reference component. Medial and lateral tibial forces were measured during passive knee flexion-extension between 0° to 120° using a custom tibial force sensor. Eight laxities were measured from 0° to 120° flexion using a six degree-of-freedom load application system. With the tibial component kinematically aligned, the increase in the tibial force imbalance from that of the reference component at 0° of flexion was sensitive to the degree of V-V malalignment of the femoral component. Sensitivities were 54N/deg (medial tibial force increasing > lateral tibial force) (p < 0.0024) and 44N/deg (lateral tibial force increasing > medial tibial force) (p < 0.0077) for varus and valgus malalignments, respectively. Varus-valgus malalignment did not significantly change varus, internal-external rotation, anterior-posterior, and compression-distraction laxities from 0° to 120° flexion. At only 30° of flexion, 4° of varus malalignment increased valgus laxity 1° (p = 0.0014). At 0° flexion, V-V malalignment of the femoral component caused the tibial force imbalance to increase significantly, whereas the laxities were relatively unaffected. Because tibial force imbalance has the potential to adversely affect patient-reported outcomes andsatisfaction, surgeons should strive to limit errors in resecting the distal femoral condyles to within ± 0.5mm which in turn limits the average increase in tibial force imbalance to 68N. Because laxities were generally unaffected, instability resulting from large increases in laxity is not a clinical concern within the ± 4° range tested. Therapeutic, Level II.

Does Use of a Jig Influence the Precision of Tibial Plateau Leveling Osteotomy Surgery?

To compare the precision of tibial plateau leveling osteotomy (TPLO) surgery when performed with or without a jig. Cadaveric study. Cadaveric, adult greyhound hindlimbs (n=9 pair). TPLO (n=18) was performed on each limb pair; 1 with and 1 without use of a jig. Measurements taken from pre- and postsurgical radiographs were osteotomy position, tibial plateau angle (TPA), varus-valgus malalignment, and tibial torsion. The null hypothesis was that TPLO precision was not affected by use of a jig. Student's t-test was used to investigate differences in TPA, osteotomy location, and frequency and extent of iatrogenic limb malalignment; P<.05 was considered significant. There were no significant differences in postsurgical TPA, tibial crest thickness, varus-valgus malalignment, or tibial torsion between TPLOs performed with or without a jig. Osteotomy location was significantly more distal when a jig was used (P=.03). Jig use did not improve the precision of TPLO surgery. Performing TPLO without a jig should reduce surgery time, eliminate complications related to placement of the distal jig pin and allow unhindered positioning of the osteotomy.

Intraoperative control of axes, rotation and length in femoral and tibial fractures technical note

In an effort to limit the amount of soft tissue dissection at the fracture site, indirect reduction and minimally invasive fixation techniques have been developed to treat femoral and tibial fractures. These techniques, which do not rely upon anatomical reduction of the fracture fragments are technically difficult. Correct limb length, axial alignment in the frontal and sagittal plane, and rotation must be assessed using means other than open reduction. In this technical note, some simple and effective intra-operative cinical examination and radiographic techniques to determine limb alignment are described. These include: the ‘cable technique’ for the determination of varus-valgus malalignment; the ‘hypertension test’, ‘radiographic recurvatum sign’, ‘tibial plateau sign’, and ‘meterstick technique’ for length analysis; and the ‘hip rotation test’, ‘lesser trochanter shape sign’, ‘cortical step sign’, and ‘diameter difference sing’ for rotational analysis. For each of the listed techniques, basis principles, technical instructions, limitations, advantages, and disadvantages are described.