Reproducibility of condylar twist angle measurement using computed tomography and axial radiography of the distal femur

Coronal and axial alignment relationship in Caucasian patients with osteoarthritis of the knee

Individualized pre-operative assessment of the patterns of the lower extremity anatomy and deformities in patients undergoing total knee arthroplasty seems essential for a successful surgery. In the present study, we investigated the relationship among the coronal alignment and the rotational profile of the lower extremities in the Caucasian population with end-stage knee osteoarthritis. We conducted a prospective study of 385 knees that underwent a pre-operative three-dimensional computed tomography-based model. The lower extremity alignment was determined (mechanical tibiofemoral or hip-knee-ankle angle, supplementary angle of the femoral lateral distal angle, and proximal medial tibial angle). For each case, the femoral distal rotation (condylar twist angle), the femoral proximal version, and the tibial torsion were determined. As the coronal alignment changed from varus to valgus, the femoral external rotation increased (r = 0.217; p < 0.0005). As the coronal alignment changed from varus to valgus, the external tibial torsion increased (r = 0.248; p < 0.0005). No correlation was found between the global coronal alignment and the femoral version. The present study demonstrates a linear relationship between the coronal alignment and the rotational geometry of the distal femur. This correlation also occurs with the tibial torsion. Perhaps outcomes of total knee arthroplasty surgery might be improved by addressing these deformities as well.

Anatomical Study of Femoral Condylar Index in Magnetic Resonance Imaging: Implication to Total Knee Replacement Surgery for Vietnamese People

BACKGROUND

The femoral rotation angle is important element in total knee replacement (TKR).

AIM

To measure this angle, we determine through the axes: the transepicondylar axis (cTEA and sTEA), the posterior condylar axis (PCA), the anteroposterior axis (APA - Whiteside axis).

METHODS

Measuring the angles created by the four axes: cTEA, sTEA, PCA and APA in magnetic resonance imaging (MRI); determining the femoral rotation angle and application TKR.

RESULTS

the angle between APA and cTEA: 90.41° ± 3.35°, the angle between APA and sTEA: 94.47° ± 3.31°, the angle between APA and PCA: 96.40° ± 4.59°, the angle between cTEA and sTEA: 4.00° ± 1.02°, the angle between cTEA and PCA: 6.53° ± 2.55°, the angle between sTEA and PCA: 3.48° ± 1.91°.

CONCLUSION

The angle between sTEA and PCA is the angle that best represents the femoral rotation angle. However, in case of sTEA or PCA is difficult to identify, it can be measure via the APA or cTEA. These angles don't differ by age, gender and place of knee joint.

Interobserver and Intraobserver Reliability of Computed Tomography-Based Three-Dimensional Preoperative Planning for Primary Total Knee Arthroplasty

BACKGROUND

Preoperative planning is an important factor for total knee arthroplasty (TKA). The aim of this study is to document the interobserver and intraobserver reliability of computed tomography (CT)-based 3-dimensional (3D) preoperative planning for primary TKA.

METHODS

Twenty knees (10 with osteoarthritis and 10 with rheumatoid arthritis) were studied independently by 6 orthopedic surgeons using a CT-based 3D planning system. The measurements were made twice at more than 3-week intervals without any knowledge of their own previous measurements or those of the others. We assessed the femoral and tibial component sizes and the alignment of the femoral component.

RESULTS

The interobserver and intraobserver agreements for femoral component size were 44.3% and 62.5% with exact size, and increased to 90.7% and 99.2% within one size difference; the intraclass correlation coefficients (ICCs) were 0.919 and 0.936, respectively. The interobserver and intraobserver agreements for tibial component size were 57.0% and 66.7% with exact size, and increased to 87.3% and 90.0% within one size difference; the ICCs were 0.909 and 0.924, respectively. The ICCs for femoral and tibial size were better in rheumatoid arthritis than in osteoarthritis. Interobserver ICC for femoral valgus angle was 0.807, and 0.893 for intraobserver reliability. Interobserver ICC of the femoral external rotation angle was 0.463, and 0.622 for intraobserver reliability.

CONCLUSION

CT-based 3D preoperative planning for primary TKA has clinical implications for predicting appropriate size and alignment of the component in patients with osteoarthritis and rheumatoid arthritis.