Objectives: The present study presents the technique to predict cubitus varus by post reduction Affected Side and Normal Side Baumann�s angle difference (ASBA and NSBA) respectively. It intends to correlate the Baumann�s angle to the final carrying angle of the injured elbow and presents the relevant mathematical clinical rule along with its prediction test characteristics.

Material and Methods: Total 57 patients of 6.5�1.67yrs, 22 were males and 8 females with 19/30 having left side injury. Isolated closed supracondylar fractures of humerus up to 5 days duration included and previous trauma, pathological fracture, other injury, elbow disease were excluded .30/57 completed >1 year follow-up.

Results: The Mean NSBA was 74.4�4.14�. The mean normal side carrying angles (NSCA) were 9.56 � 2.2�. The NSCA IQR (Inter Quartile Range) was 8.8-10�. The ASBA was 79.9�9.1� and affected side carrying angles (ASCA) was 0.20�8.7�. The ASCA was best predicted by the difference between ASBA-NSBA (ASCA=3.87-0.65(ASBANSBA; F=15.91). At a cut off of 8.8� (the lower limit of IQR for NSCA), a value >0� for ASBA- NSBA was 80% predictive of cubitus varus. With pre test probability of varus at 70%, sensitivity was 0.94 and specificity 0.42.

Discussion: A prediction rule to predict the final carrying angle from ASBA NSBA difference is presented with a positive predictive value 0.80, specificity of 0.42, and sensitivity of 0.94 at a pre test probability of 0.70.When the diagnosis of cubitus varus is ASCA<8.8� (Lower limit of the IQR for NSCA).

Conclusion: If affected side Baumann�s Angle � Normal Side Baumann�s Angle is equal to or greater than 0 then there was 80% probability of having cubitus varus.