A novel and reproducible reference axis for distal tibial axial rotation

The tibial tubercle-to-trochlear groove distance changes in standing weight-bearing condition: An upright weight-bearing computed tomography analysis

BACKGROUND

The tibial tubercle-to-trochlear groove (TT-TG) distance and Insall-Salvati (I/S) ratio are widely used to determine the need for distal realignment in conjunction with medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent patellar dislocation. A TT-TG distance >20 mm and an I/S ratio >1.3 are significant anatomical risk factors for patellar instability. However, these parameters have traditionally been measured using non-weight-bearing (NWB) imaging modalities. As patellar dislocation occurs during weight-bearing actions, these two parameters should be measured under weight-bearing conditions. Thus, this study aimed to measure the TT-TG distance and I/S ratio using upright full-weight-bearing (FWB) computed tomography (CT) scans and compare the data with NWB CT scans.

METHODS

This study included 49 knee joints of 26 healthy volunteers. CT images were obtained under both FWB and NWB standing conditions using a 320-detector row upright CT scanner. TT-TGs in the axial plane and I/S ratios in the sagittal plane were measured and compared.

RESULTS

The average FWB TT-TG distance was 20.3 ± 3.9 mm, whereas the average NWB TT-TG distance was 12.3 ± 4.7 mm. The TT-TG level was significantly higher in the FWB condition than that in the NWB condition (P < 0.001). The I/S ratios were comparable between the FWB and NWB conditions (P = 0.29).

CONCLUSIONS

The TT-TG distance in the standing weight-bearing condition was larger than the conventional TT-TG distance and surpassed the historical cutoff value of TT-TG, which may affect the indication of additional distal realignment in MPFL reconstruction for patellar instability.

Extra-articular location of the three-dimensional mechanical axis in advanced knee osteoarthritis: an upright computed tomography study

PURPOSE

One of the most widely used benchmarks of lower-limb alignment is the mechanical axis (MA), which passes through the centers of the femoral head and the ankle in the weight-bearing position. However, where the MA passes through three-dimensionally (3D) is unclear. We investigated the MA in 3D (3D-MA) in knee osteoarthritis (OA) using upright computed tomography (CT).

MATERIALS AND METHODS

This study included 66 varus OA knees from 38 patients [age 70.0 (64.8-77.0) years; median (interquartile range)]. The 3D-MA was determined using upright CT data and compared among Kellgren-Lawrence (KL) grades. Further, correlations between the 3D-MA and other parameters were evaluated.

RESULTS

The 3D-MA was located at 5.3 (1.3-14.4)% medially and 7.1 (0.7-15.3)% posteriorly on the tibial plateau in KL-1, and was translated medioposteriorly with increased KL grade. The 3D-MA in KL-3 [30.6 (22.6-42.6)% medially and 50.9 (45.8-80.2)% posteriorly] and KL-4 [56.7 (48.5-62.9)% medially and 92.3 (50.2-127.1)% posteriorly] was located extra-articularly. The mediolateral position of the 3D-MA correlated with the femorotibial angle [correlation coefficient (CC) = - 0.85, p < 0.001], and the anteroposterior position of the 3D-MA correlated with the knee flexion angle (CC = - 0.93, p < 0.001).

CONCLUSION

Our analysis demonstrated that the 3D-MA in low-grade OA knees passes slightly medial and posterior to the knee center, and the 3D-MA is translated medioposteriorly with the progression of knee OA. Further, the 3D-MA is translated medially with varus progression and posteriorly with the progression of knee flexion contracture.

Three-dimensional joint surface orientation does not correlate with two-dimensional coronal joint line orientation in knee osteoarthritis: Three-dimensional analysis of upright computed tomography

BACKGROUND

Two-dimensional (2D) coronal joint line orientation on radiography under weight-bearing conditions has been widely used in evaluating knee osteoarthritis (OA). However, the effects of tibial rotation remain unknown. The present study aimed to newly define three-dimensional (3D) joint surface orientation relative to the floor as an unchangeable 3D angle unaffected by tibial rotation using upright computed tomography (CT), and to investigate correlations between 3D and 2D parameters in knee OA.

METHODS

Sixty-six knees in 38 patients with varus knee OA underwent standing hip-to-ankle digital radiography and upright CT. The 2D parameters measured on radiographs included femorotibial angle (FTA), tibial joint line angle (TJLA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). The 3D inner product angle between vectors of the tibial joint surface and the floor from CT was defined as the 3D joint surface-floor angle.

RESULTS

Mean 3D joint surface-floor angle was 6.0 ± 3.6°. No correlation was identified between 3D joint surface-floor angle and 2D joint line parameters, even though FTA correlated substantially with 2D joint line parameters. No significant differences in 3D joint surface-floor angle were identified among Coronal Plane Alignment of the Knee (CPAK) types.

CONCLUSIONS

The 3D joint surface orientation did not correlate with 2D coronal joint line orientation and was unaffected by CPAK classification types. This finding suggests that current 2D evaluations should be reconsidered for a better understanding of true knee joint line orientation.

A novel anteroposterior axis of the tibia for total knee arthroplasty: An upright weight-bearing computed tomography analysis

BACKGROUND

The traditional anteroposterior (AP) axis (i.e., Akagi's line) has been widely used as the tibial component AP axis during total knee arthroplasty (TKA). However, this AP axis has been defined based on computed tomography (CT) in a non-weight-bearing supine position. In this study, AP axes of the tibial plateau from upright CT in weight-bearing and non-weight-bearing positions were determined and compared.

METHODS

This study included 43 knees from 23 healthy volunteers. CT images were obtained in weight-bearing and non-weight-bearing standing positions using a 320-detector row upright CT scanner. The line perpendicular to surgical transepicondylar axis projected onto the tibia plateau was determined as the AP axis in upright weight-bearing and non-weight-bearing conditions. Angular differences between these two conditions were measured.

RESULTS

The upright weight-bearing AP axis was positioned in a mean of 7.4 ± 4.3° of internal rotation relative to the traditional AP axis. Distance between the traditional and upright weight-bearing AP axis was 2.9 ± 1.6 mm at the edge of the tibial plateau. The upright non-weight-bearing AP axis was positioned in a mean of 3.5 ± 4.1° of internal rotation relative to the traditional AP axis. Mean angular difference between weight-bearing and non-weight-bearing conditions was 3.9 ± 4.1°.

CONCLUSIONS

The upright weight-bearing AP axis was positioned in 7.4° of internal rotation relative to the traditional AP axis, showing one-seventh of the tibial tuberosity away from the medial border of the tibial tubercle, which represents a practical landmark for the tibial component AP axis during TKA.

Increase in tibial internal rotation due to weight-bearing is a key feature to diagnose early-stage knee osteoarthritis: a study with upright computed tomography

Background

The classification of knee osteoarthritis is an essential clinical issue, particularly in terms of diagnosing early knee osteoarthritis. However, the evaluation of three-dimensional limb alignment on two-dimensional radiographs is limited. This study evaluated the three-dimensional changes induced by weight-bearing in the alignments of lower limbs at various stages of knee osteoarthritis.

Methods

Forty five knees of 25 patients (69.9 ± 8.9 years) with knee OA were examined in the study. CT images of the entire leg were obtained in the supine and standing positions using conventional CT and 320-row detector upright CT, respectively. Next, the differences in the three-dimensional alignment of the entire leg in the supine and standing positions were obtained using 3D-3D surface registration technique, and those were compared for each Kellgren–Lawrence grade.

Results

Greater flexion, adduction, and tibial internal rotation were observed in the standing position, as opposed to the supine position. Kellgren–Lawrence grades 1 and 4 showed significant differences in flexion, adduction, and tibial internal rotation between two postures. Grades 2 and 4 showed significant differences in adduction, while grades 1 and 2, and 1 and 3 showed significant differences in tibial internal rotation between standing and supine positions.

Conclusions

Weight-bearing makes greater the three-dimensional deformities in knees with osteoarthritis. Particularly, greater tibial internal rotation was observed in patients with grades 2 and 3 compared to those with grade 1. The greater tibial internal rotation due to weight-bearing is a key pathologic feature to detect early osteoarthritic change in knees undergoing osteoarthritis.

Relationship between lower limb torsion and coronal morphologies of the femur and tibia in patients with medial knee osteoarthritis

Background

To 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).

Methods

A 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.

Results

The 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.

Conclusion

Femoral and tibial torsions were correlated with varus inclination of the proximal tibia in patients with medial knee OA.

[Treatment of rotational malalignment of the lower leg]

BACKGROUND

Rotational malalignment after intramedullary nailing of tibial shaft fractures is not uncommon. In-toeing and out-toeing conditions in children are often the reason for orthopedic and traumatological medical consultation.

OBJECTIVE

Evaluation of diagnostic modalities and therapeutic options for rotational malalignment in relationship to the patient's age. Surgical indications and efficacy of specific surgical techniques.

MATERIAL AND METHODS

Systematic literature search in the German Institute for Medical Documentation and Information (DIMDI) and MEDLINE and evaluation of the currently published articles.

RESULTS

In adults computed tomography (CT) scanning is the gold standard for measuring the rotational alignment of the lower leg. To avoid exposure to ionizing radiation, magnetic resonance imaging (MRI) is currently the preferred modality in children and adolescents. The indications for corrective osteotomy are dependent on the functional complaints as well as the rotation angle measured by CT or MRI. Presently, there is no published study which demonstrates a correlation between rotation of the lower leg and the development of arthrosis in the knee or ankle joint. When a rotational osteotomy above the tibial tubercle is performed, correction of the rotation and the distance between the tibial tuberosity and the trochlear groove (TT-TG) and therefore patellofemoral imbalance can be effectively treated. Treatment of rotational malalignment after tibial shaft fractures is performed by diaphyseal osteotomy with intramedullary nail stabilization. In children, supramalleolar rotational osteotomy with subsequent locking plate osteosynthesis or stabilization using external fixation is performed for torsion correction.

CONCLUSION

If there is a suspicion of rotational malalignment in the lower leg, a CT scan can be performed in adults and MRI in children and adolescents. Surgical indications for corrective osteotomy are dependent on functional complaints as well as the CT and MRI measurements. The CT and MRI reference values are only published according to the method of Waidelich et al. and Jend et al.

Total knee replacement modifies the preoperative tibial torsion angle-similar results between computer-assisted and standard technique

Background

Malpositioning of the components in total knee replacement (TKR) can result in failure or deficient outcomes of the surgical procedure. In the tibial segment, the rotational position of the tray should reproduce the mechanical axis without modifying physiological tibial torsion.

Methods

A randomised, prospective study was made of 74 patients subjected TKR involving the standard technique (38 cases) and navigation surgery (36 cases). A computed tomography study of the knee and ankle was made before the operation and after arthroplasty implantation, in order to identify the position of the prosthetic tibial tray in the transverse axis and the tibial torsion angle.

Results

The rotation of the tibial tray changed from its preoperative to postoperative range, but no significant differences were found between the navigated and the standard groups. The presence of preoperative deformities in the frontal plane did not modify the changes in the rotation of the tibial component. The mean preoperative tibial torsion angle was 17.76º (SD =10.15) of external rotation, with no significant differences in relation to the previous frontal deformity. After TKR, the tibial torsion angle was 15.36º (SD =7.16) (P=0.021). There were no differences in final tibial torsion between the knees operated upon with the standard instruments and those subjected to computer-assisted surgery (CAS; P=0.157).

Conclusions

TKR surgery modifies preoperative tibial torsion. Neither mechanical instrumentation nor navigation surgery precisely reproduces the rotational axis of the leg.

The tibial growth plate as a predictor of the original tibial plateau joint line as a reference for kinematically aligned total knee arthroplasty

Background

Restoration of the natural joint line is a cornerstone for kinematically aligned total knee arthroplasty (TKA). The purpose of this study was to investigate the relative orientation of the tibial growth plate (GP) with respect to the tibial plateau (TP) for possible application in predicting natural joint line for knees with highly advanced osteoarthritis patient at the time of kinematically aligned TKA.

Methods

Images from computed tomography (CT) of 27 normal knees (9 males, 18 females; mean age, 31.6 years) were studied. Geometry of the GP was extracted from CT images, and its moment-of-inertia axes were calculated for the whole GP and the medial and lateral halves. Angular orientations of each GP axis with respect to the TP plane were measured in anatomical coordinates.

Results

The TP and GP planes were oriented in 2.3 ± 1.8° of varus and 1.1 ± 1.9° of valgus relative to the tibial mechanical axis, respectively. With respect to the TP plane, the whole GP plane was inclined in 3.4 ± 1.5° of valgus. Orientation of the GP plane differed drastically between medial and lateral halves. The medial GP was in 4.9 ± 2.9° of varus and 1.8 ± 2.5° of anterior inclination, and the lateral half was in 10.4 ± 2.4° of valgus and 18.6 ± 4.0° of anterior inclination relative to the TP.

Conclusions

Angular orientation of the original TP plane can be predicted in reference to the GP plane and may provide reasonable guidance for the target bone resection angle of the tibia in kinematically aligned TKA.

Femoral Version and Tibial Torsion are Not Associated With Hip or Knee Arthritis in a Large Osteological Collection

BACKGROUND

Tibial torsion and femoral anteversion are common rotational abnormalities in children, and their courses are most often benign and self-resolving. Although neither usually requires surgical treatment, the decision to perform a derotational osteotomy is usually based on the degree of functional impairment. Neither condition is thought to influence the development of osteoarthritis of the hip or knee; however, to date there have been no large scale studies confirming this.

METHODS

Tibial torsion and femoral version in 1158 cadaveric tibiae and femora were measured using a camera setup based on previously described radiographic landmarks. Any specimens with obvious traumatic, rheumatic, or metabolic abnormalities were excluded. Degenerative joint disease of the hip and knee were each graded from 0 to 6. Correlations between tibial torsion, femoral version, age, race, and sex with osteoarthritis of the hip and knee joints were evaluated with multiple regression analysis.

RESULTS

The mean and SDs of tibial torsion and femoral anteversion were 7.9±8.8 and 11.4±12.0 degrees, respectively. African Americans had significantly increased tibial torsion (5.1±8.7 vs. 9.2±8.5 degrees, P<0.0005) and greater femoral anteversion (14.1±11.9 vs. 10.2±11.8 degrees, P<0.0005) compared with whites. The average grades for hip and knee osteoarthritis were 3.1±1.4 and 2.7±1.4. Using multiple regression analysis neither tibial torsion nor femoral version were independent predictors of hip or knee arthritis (P>0.05 for all).

DISCUSSION

This study confirmed previously reported differences in the rotational profiles between races and sexes. However, neither tibial torsion nor femoral anteversion had a significant influence on the development of arthritis of the hip or knee.

CLINICAL RELEVANCE

These results support the practice of treating tibial torsion and femoral anteversion based on the symptomatology of the patient. Parents of asymptomatic children can be reassured that long-term consequences are unlikely.