2017 ISAKOS Biennial Congress ePoster #1281

 

Ct Measurement Of Distal Femoral Valgus Angle In Indian Population

Raju Vaishya, MBBS, MS, MCh, FRCS, New Delhi INDIA
Ifeanyi Charles Nwagbara, MBBS, FMCS(ortho), New Delhi, Delhi NIGERIA
Amit Kumar Agarwal, MBBS,MS,DNB,MCh,Dip.sicot, Ghaziabad, Uttar Pradesh INDIA
Vipul Vijay, MS, DNB, New Delhi, Delhi INDIA

Indraprastha Apollo Hospital, New Delhi, Delhi, INDIA

FDA Status Not Applicable

Summary

In a prospective study (134 knees) involving the analysis of the CT scans of knee (in patients undergoing TKA) shows that a wide variation in DFVA exists in Indian population and it is recommended that preoperative measurement of DFVA should be done; if fixed valgus angle cutting jig is used, then a distal femoral cut at 6 degrees during TKA may achieve a good result.

Abstract

Background

The restoration of the mechanical alignment of the limb in total knee arthroplasty (TKA) has been shown to reduce the incidence of loosening significantly and improve the long-term survival of the prosthesis. During surgery, the alignment of the limb is restored by appropriately placed bone cuts augmented by soft tissue release. The distal femoral bone cuts are conventionally made with jigs that are oriented along the anatomical axis of the femur to achieve this fixed valgus angle of 50 or 60.It assumes that the distal femoral valgus angle (DFVA) of most individuals will fall within 30 of this value. There may, however, be wide variations in the femoral anatomy that can significantly alter the DFVA outside the acceptable margin. The aim of this study is to determine the normal variability of the DFVAin the Indian population using Computed tomography (CT) scans and to determine the appropriateness of using fixed angle jigs.

Materials And Methods

This prospective study involved the analysis of the CT scans of patients who were being investigated for knee osteoarthritis using a standard protocol.The DFVA is defined as the angle between the anatomical and mechanical axes of the femur in the coronal plane. The mechanical axis is defined as the line joining the centre of the femoral head, and the centre of the knee joint and the anatomical axis is the line joining the centre of the knee and the centre of the femoral shaft. The angle between the mechanical and anatomical axes was measured. The values of the DFVA obtained were subjected to Student’s t-test and Pearson correlation coefficient to evaluate the statistical correlation between the gender, age, and side.

Results

One hundred and thirty-four knees in 78 patients (59 females and 19 males) were involved in the study. The knees were bilateral in 59 cases and unilateral in 16 cases. The average age of the patients was 63.84 years (range: 43-86 years). The average DFVA for the whole study population was 5.830(range of 4-7.5). It was 5.860 for the left side and 5.800 for the right side. The value for males was 5.810 and for females, it was 5.840.There was no statistically significant difference (P> 0.05) between the DFVA on the left and right side or between the males and females on either side. There was a positive correlation between the DFVA on the left and right side for each patient (R2= 0.752; P< 0.01) but no significant relationship between the DFVA with the age of the patient.

Conclusion

Wide variation in DFVA exists in Indian population. It is recommended that preoperative measurement of DFVA should be done, and an appropriate femoral cut is made during TKA surgery. If a fixed valgus angle cutting jig is used, then a distal femoral cut at 6 degrees during TKA may achieve a good result in restoring the natural mechanical alignment of the lower extremity in Indian patients.