The Effect of Sagittal Knee Deformity on Preoperative Measurement of Coronal Mechanical Alignment during Total Knee Arthroplasty.

PURPOSE: The purpose of this prospective study was to determine correlation between coronal mechanical alignment measured on preoperative standing full-length radiographs and navigation during total knee arthroplasty (TKA) in the presence of an associated sagittal deformity (hyperextension and flexion deformity). MATERIALS AND METHODS: Coronal mechanical alignment measured on preoperative, standing, full-length, hip-to-ankle anteroposterior radiographs was compared with intraoperative measurements recorded with computer navigation in 200 primary navigated TKAs. RESULTS: The mean difference in mechanical alignment between the two techniques was significantly greater (p=0.001) in patients with an associated flexion deformity >10° when compared to knees with associated flexion deformity ≤10°; 48% of knees with a flexion deformity >10° had a difference of ≥3° between the full-length radiograph and navigation alignment measurements. There was a strong correlation between the radiographic and navigation measurement techniques. CONCLUSIONS: The mean difference in coronal mechanical alignment between the two techniques was significantly higher in patients with an associated flexion deformity >10°. Hence, surgeons should take caution when relying on preoperative full-length radiographs for determining coronal mechanical alignment in patients with an associated flexion deformity >10° where using navigation may be more reliable.

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

PURPOSE: We aimed to determine variation in femoral valgus correction angle (VCA) between the two limbs in a patient with windswept deformity undergoing total knee arthroplasty (TKA). METHODS: Femoral VCA was measured on full-length, hip-to-ankle, standing radiographs and was compared between the varus and the valgus limbs in 66 patients with windswept deformities. RESULTS: The mean VCA in varus knees was significantly higher compared to mean VCA in valgus knees (p = 0.002). CONCLUSION: Significant difference in VCA is present between the varus and the valgus limbs in most patients with windswept deformity undergoing TKA.