Mid-sulcus line predictive guide for tibial mechanical axis during TKA

Alok Umre et al found in a study that-"Mid-sulcus line can be used as an additional anatomical landmark to guide the tibial resection and thereby achieve appropriate coronal alignment in primary TKAs without any extra-articular deformity."

Achieving appropriate alignment of components in total knee arthroplasty (TKA) is essential for optimal functional outcomes as well as implant longevity. Performing TKA in the absence of a computer-assisted navigation system (CANS) mandates the use of accurate anatomical landmarks for achieving appropriate alignment. In this study, authors have evaluated the reliability of ‘mid-sulcus line’ as an anatomical landmark to guide tibial resection, with the intra-operative help of CANS.

The study was conducted at Department of Orthopaedics, Arogyam Superspeciality Hospital, Nagpur, India. The article has been published in ‘The Knee’ journal. A total of 322 patients undergoing primary TKA (excluding previously operated limbs and limbs with extra-articular deformities of tibia or femur) using CANS were included in the study. After resecting ACL, the mid-sulcus line was drawn with a cautery tip. The authors hypothesized that if tibial cut was made perpendicular to the mid-sulcus line, coronal alignment of the tibial component would be along the neutral mechanical axis. This was evaluated intra-operatively with the help of CANS.

Key findings of the study were:

• A total of 279 patients were found to have pre-operative varus alignment with mean deformity of 5.60 (range, 0.5–260). Forty-three patients were found to have pre-operative valgus alignment with mean deformity of 5.20 (range, 0.5–180).

• Of 322 knees, identification of the ‘mid-sulcus line’ was possible in 312 knees.

• The mean angle between the tibial alignment defined by mid-sulcus line and the neutral mechanical axis was found to be 0.450 (range, 0–1.50) (P < 0.05).

• In all of the 312 knees, the tibial alignment defined by mid-sulcus line was found to be within 30 of the neutral mechanical axis (confidence interval: 0.4100, 0.4910).

Further reading:

Is mid-sulcus line a predictive guide for tibial mechanical axis during total knee arthroplasty? A. Umre, O. Wakde and R. Meghare The Knee 41 (2023) 373–379 https://doi.org/10.1016/j.knee.2023.02.003