Summary

Popliteal artery injury during medial UKA is rare but significant. This study analyzed 172 knees from 154 patients, using preoperative MRI to measure the artery's position at the tibial osteotomy level. In 44.2% of cases, the artery was medially located, particularly in severe varus deformities. Preoperative identification of the artery’s position is essential to prevent complications.

Abstract

【Introduction】Injury of popliteal artery during medial unicompartmental knee arthroplasty (UKA) is a relativity rare but have serious complications. However, due to the small number of cases of this injury, limited number of articles have examined in detail the anatomical location of the popliteal artery. In this study, we investigated the distance and positional relationship to the popliteal artery (PA) at the tibial osteotomy plane in the cases of medial UKA.
【Subjects and Methods】We reviewed 154 patients, 172 knees of medial UKA performed at our hospital from 2019 to 2024 (51 male, 103 female). The mean age at the time of operation was 76.6 ± 7.5years (mean ± SD, range 49-93). From the preoperative MRI, axial images were evaluated. At the tibial bone cutting level, we measured the distance between the posterior cortex of the tibia and the anterior border of the PA (D-PA). Additionally, the distance between the medial border of the tibia and the center of the PA is divided by transverse diameter of the tibia, then expressed as % (medial edge 0%, lateral edge 100%)(%-PA). Less than 50% considered to be medial location. The correlation between limb alignment, such as hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle (MPTA), and obtained values were analyzed.
【Results】The values of D-PA and %-PA were 3.9 ± 2.4 mm (range, -2.9-12.8) and 51.2 ± 6.9 % (range, 30.0-70.3), respectively. In 76 cases (44.2%), the %-PA was presented less than 50%, the PA run medially to the center of the tibia at the tibial bone cutting level. There was positive correlation between HKA and D-PA (P=0.0104). The MPTA demonstrated positive correlation with D-PA (P=0.0334). There was no correlation between limb alignment and %-PA.
【Discussion】Although the risk of PA injury during tibial bone cutting in UKA has generally been considered low, it is anticipated that there may be cases with a higher risk of PA injury according to present study. Of note, over 40% of medial UKA cases demonstrated the anatomically medial localized PA in the tibial cutting plane. Therefore, preoperative identification of the position of the PA and careful bone cutting maneuver with protection will be deemed important.
【Conclusion】
This study demonstrated that the more severe varus alignment, the closer the PA is located to the posterior tibial margin. Of note, in 44.2% of UKA cases PA runs medial at the level of tibial bone cutting plane.