Individualised distal femoral cut improves femoral component placement and limb alignment during total knee replacement in knees with moderate and severe varus deformity

Abstract

Level 2.

Windswept deformities – An indication to individualise valgus correction angle during total knee arthroplasty

“…Our results showing variation in VCA between the varus and valgus knee in windswept knees undergoing TKA is validated by similar studies done by other investigators in arthritic knees undergoing TKA. Mullaji et al, 4 in an analysis of 503 knees undergoing TKA reported that 56% of knees had VCA outside the usual range of 5-78 whereas Palanisami et al, 5 in an analysis of 227 knees reported that 31% of knees had VCA outside the usual range of 5-78. This is similar to our study where 38% of knees had VCA outside the usual range of 5-78.…”

“…[4][5][6][7][8] Individualising the VCA is crucial during TKA in order to achieve accurate limb and femoral component alignment and minimising errors especially in the presence of severe deformity or excessive femoral bowing of the femoral shaft. 5,7 Hence, in view of the significant difference in mean VCA between the varus and the valgus knee, windswept deformities undergoing TKA is an indication for the surgeon to preoperatively measure femoral VCA on full-length hip-to-ankle radiographs in order to minimise error. Limitations of this study include the retrospective nature of the study with its inherent drawbacks and biases and a relatively small number of study subjects considering the inherent rarity of windswept deformity in arthritic knees.…”

“…4 Although, it is recommended that a standard range of 5-78 VCA be used while performing the distal femoral cut, studies have reported significant variation in VCA among individual knees undergoing TKA when measured on full-length standing hip-to-ankle radiographs. [4][5][6][7] Furthermore, individualising the VCA during TKA will result in more accurate restoration of the limb alignment and positioning of femoral component in the coronal plane, especially in the presence of severe varus or valgus deformities and significant femoral bowing. [4][5][6][7][8] Hence, variation in VCA based on the type of knee deformity is more relevant in patients with windswept deformity undergoing TKA where VCA may be significantly different in varus knee when compared to the valgus knee.…”

Comparison of Valgus Correction Angle between Patients with Developmental Dysplasia Hip and Normal Volunteers Measured by Three-Dimensional Reconstruction and X-Ray

“…In previous studies, Mullaji et al reported that 56% of 503 knees undergoing TKA had VCA outside the normal range of 5°-7° [ 14]. Shetty et al reported that 38% of 100 knees undergoing TKA had VCA outside the range of 5°-7° [15]; Palanisami et al reported 31% of 227 knees undergoing TKA had VCA outside 5°-7° [16]. The results of our research measured by 3D indicated that 18% of 112 knees of normal volunteers had VCA outside 5°-7°; 56% of 100 knees of DDH patients had VCA outside 5°-7°.…”

“…However, the femora of some DDH patients are usually abnormal in femoral bowing. In such cases, the intramedullary rod implanted into a distal femur along with the femoral anatomical axis can cause stress concentration and fracture [16]. The lower VCA is more in line with the operation in these cases compared to the upper VCA.…”