JOA - 2026-09-09 - Journal Article
The Effect of Posterior Tibial Slope Change on Functional Outcomes After Posterior-Stabilized Total Knee Arthroplasty: An Analysis of 370 Patients Who Had A Minimum 4-Year Follow-Up.
Altun O, Ergişi Y, Özdemir E, Özihtiyar AA, Altıntaş M, Daşar U
Topics
Key Takeaway
In 370 PS-TKA patients at mean 64.6 months follow-up, neither the direction nor magnitude of posterior tibial slope change (mean absolute change 5.47°) was associated with postoperative pain, functional scores, or ROM in any clinically meaningful way.
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Summary
This single-center retrospective cohort examined whether postoperative PTS change—analyzed by direction, magnitude, and a 5.47° mean-change cutoff—affected functional outcomes in 370 primary cemented PS-TKA patients at minimum 4-year follow-up. No association was found between PTS change and VAS, WOMAC, KSS, OKS, FJS-12, or overall clinical improvement (all P>0.05). Each 1° increase in PTS produced a statistically significant but clinically negligible 0.53° gain in flexion, and preoperative functional status was the dominant predictor of postoperative outcomes.
Key Limitation
The study is restricted to a single PS implant design at one center, so findings cannot be extrapolated to CR-TKA or other PS systems where cam-post geometry and slope sensitivity differ substantially.
Original Abstract
BACKGROUND
Posterior tibial slope (PTS) is an important sagittal alignment parameter in posterior-stabilized total knee arthroplasty (PS-TKA). Although excessive PTS may influence knee biomechanics, the clinical relevance of postoperative PTS changes remains controversial.
METHODS
This single-center retrospective cohort study included 370 patients who underwent primary cemented PS-TKA using a single implant design, with a minimum follow-up of 48 months. The cohort consisted of 370 patients who had a mean age of 71 years (range, 55 to 90) and a mean follow-up duration of 64.6 months (range, 48 to 74). Sex distribution and operated side were comparable across PTS change groups. Preoperative and postoperative PTS were measured on standardized lateral radiographs. Posterior tibial slope measurements were performed independently by two blinded observers, and interobserver reliability was assessed using intraclass correlation coefficients. The PTS change was analyzed according to direction (decrease, neutral, or increase), magnitude (≤3, 4 to 9, and ≥10°), and a cut-off based on the mean absolute change (5.47°). Clinical outcomes included Visual Analog Scale, Western Ontario and McMaster Universities Osteoarthritis Index, Knee Society Score, Oxford Knee Score, Forgotten Joint Score-12, and knee range of motion. Multivariable statistical analyses were performed.
RESULTS
All patient-reported outcome measures demonstrated significant improvement following surgery. Neither the direction nor the magnitude of PTS change was associated with postoperative pain, functional outcomes, or overall clinical improvement (all P > 0.05). An increase in PTS was associated with a modest increase in postoperative knee flexion (0.53° per one-degree increase; P < 0.001); however, this gain in range of motion did not translate into improved patient-reported functional outcomes. Across all analyses, preoperative functional status was the strongest predictor of postoperative results.
CONCLUSION
Within accepted surgical ranges, changes in PTS do not have a clinically meaningful impact on functional outcomes after PS-TKA. Postoperative success appears to be driven primarily by preoperative functional status rather than by small deviations in tibial slope.