JOA - 2026-05-08 - Journal Article
Standardized Sagittal Alignment Targets Fail to Restore Native Medial and Lateral Posterior Tibial Slope in Primary Total Knee Arthroplasty.
Hwang R, Quevedo-Gonzalez F, Burgio C, Zepeda K, Debbi E, Mayman D
Topics
Key Takeaway
A standardized 3° posterior tibial slope target would deviate >4° from native medial PTS in 51% and native lateral PTS in 71% of primary TKA patients.
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Summary
This study quantified medial and lateral posterior tibial slope (PTS) on preoperative CT in 591 consecutive robotic-assisted TKA patients to determine how often standardized sagittal targets fail to match native anatomy. Mean medial PTS was 6.9° and mean lateral PTS was 9.3° (P<0.01), with women demonstrating greater medial PTS than men (7.5° vs 6.4°, P<0.01). Applying a standardized 3° PTS target would produce >4° deviation from native medial slope in 51% and native lateral slope in 71% of patients.
Key Limitation
The absence of postoperative slope data and patient-reported outcomes means the functional and biomechanical consequences of slope mismatch cannot be determined from this dataset.
Original Abstract
INTRODUCTION
Prior studies report high variability of the posterior tibial slope (PTS) in patients undergoing total knee arthroplasty (TKA). However, these studies are often performed using radiographs and do not differentiate between the medial and lateral PTS. The purpose of this study was to report the medial and lateral PTS using computed tomography (CT) on patients undergoing primary TKA.
METHODS
Retrospective analysis was performed on 591 consecutive patients undergoing a robotic-assisted TKA from May 2023 to November 2024. Preoperative CT scans were obtained as part of the standard CT-based planning workflow and used to measure the medial and lateral PTS relative to the tibial mechanical axis.
RESULTS
The mean medial PTS was 6.9° (range, -5.9 to 25.8°), while the mean lateral PTS was 9.3° (range, -3.4 to 24.6°) (P < 0.01). The medial PTS was greater for women (mean 7.5°, range, -3.9 to 25.8°) than men (mean 6.4°, range, -5.9 to 21.1°) (P < 0.01). The lateral PTS was 9.1° (range, -3.4 to 24.6°) for women and 9.6° (range, -0.4 to 23.7°) for men (P = 0.09). There were 45% of patients who had a medial PTS of greater than 3° from the mean, while there were 40% of patients who had a lateral PTS of greater than 3° from the mean. Using a standardized sagittal alignment target of 3° of PTS would result in greater than 4° deviation from the native medial and lateral PTS in 51 and 71% of patients, respectively.
CONCLUSION
Patients undergoing primary TKA demonstrate high variability in medial and lateral PTS as measured on preoperative CT. The use of standardized sagittal alignment targets in TKA will alter the medial and lateral PTS in a large proportion of patients. Additional studies are needed to determine the optimal target for PTS in patients undergoing primary TKA.