Computerized tomography based “patient specific blocks” improve postoperative mechanical alignment in primary total knee arthroplasty

Table 1 comparison of post-operative mechanical femoral tibial angle between the patient specific block group and the conventional group

	PSB group(n = 40)Mean ± SD	Conventional group(n = 40)Mean ± SD	Mean difference	P value
Postop MFT angle	178.23 ± 2.67	175.73 ± 3.62	2.497	0.001

Postop: Post operation; MFT: Mechanical femoro-tibial; PSB: Patient specific blocks.

Table 2 Comparison of computerized tomography based and magnetic resonance imaging based patient specific blocks

	Computerized tomography based blocks	Magnetic resonance imaging based blocks
Time for study	Lesser (approximately 5 min)	Longer (approximately 45 min)
Cost	Economical	Costlier
Radiation exposure	Uses ionizing radiation. But focused hip-knee-ankle computerized tomography scanogram reduces exposure to 5 mSv (equal to yearly background exposure)	Does not use ionizing radiation
Availability	Easily available	Not available at all centers
Patient turn over	Useful for high patient turnover centers	Not suitable for high patient turnover center
Contraindication	Can be used in patient with any metal prosthesis in situ	Cannot be used in patient with metal prosthesis or cardiac pacemaker in situ
Based on	Bony landmarks	Cartilage
Accuracy	Comparable	Comparable
Initial infrastructure set up cost	Lower as compared to MRI	High, non affordable for low volume centres
Claustrophobia	No contraindication	Can not be performed in claustrophobic patients

MRI: Magnetic resonance imaging.