Anterior versus Posterior Total Knee Arthroplasty Referencing Shows comparative Outcomes, Suggests Study

The optimal femoral sizing technique in primary total knee arthroplasty (TKA)—anterior (AR) versus posterior referencing (PR)—remains debated due to patient-specific anatomical differences. To eliminate these confounding variables, Tapasvi et al. prospectively compared AR and PR functional outcomes directly within the exact same patients undergoing simultaneous bilateral TKA.

Therefore, the two-year prospective study evaluated 81 osteoarthritis patients with symmetrical bilateral varus deformities. By implanting identical posterior-stabilized systems—randomizing anterior referencing to one knee and posterior referencing to the other—clinicians directly compared radiographic, operative, and functional outcomes within the exact same patients. Complex deformities and inflammatory arthritis were excluded to ensure an accurate, highly controlled clinical comparison.

Key Clinical Findings of the Study Includes:

• Bone Resection Equality: Investigators reported that the mean values for both distal femoral and proximal tibial bone cuts were nearly identical with no statistical significance between the two techniques.

• Implant Size Consistency: Authors found that the femoral implant sizes were exactly the same in 60.5% of the simultaneous surgeries, maintaining a comparable mean polyethylene thickness of 5.86 mm for AR and 5.81 mm for PR.

• Offset Preservation: Researchers noted that the mean postoperative posterior condylar offset ratio remained stable and comparable across both groups, measuring 0.47 in the AR knees and 0.46 in the PR knees.

• Functional Parity: Clinicians demonstrated that the two-year mean flexion ranges (125.3° for AR versus 124.4° for PR) and improvements in the Revised Oxford Knee Scores (ROKS) were virtually indistinguishable.

• Patient Preference: Scientists revealed that 83.5% of the subjects expressed absolutely no preference for either the AR or PR knee at their final follow-up assessment.

The results suggest that knees sized with anterior referencing yield identical functional outcomes to those using posterior referencing, as evidenced by completely comparable two-year flexion ranges and functional improvement scores. When utilizing a modern knee system that offers multiple sizing increments, both referencing techniques prove highly acceptable with no discernable differences across all measured clinical parameters.

Thus, the study concludes orthopedic surgeons can comfortably choose either anterior or posterior femoral referencing based on their intraoperative judgment, provided careful balancing is achieved, as neither technique inherently compromises the patient's postoperative joint functionality.

The study is limited by its modest sample size, a higher proportion of female subjects, and the strict exclusion of complex deformities like valgus or posttraumatic arthritis. Consequently, it may be beneficial to gently explore how these two referencing techniques perform across a wider array of structural knee variations in future clinical evaluations.

Reference

Tapasvi, S. R., Chowdhry, M., Shekhar, A., Tapasvi, K. S., Dipane, M. V., & McPherson, E. J. (2026). Comparing Anterior Versus Posterior Size Referencing in Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty: One Technique Per Knee. Indian Journal of Orthopaedics, 60, 696–703.