A simple planning tool for tibial slope osteotomy-Osteotomy depth is a precise parameter to determine wedge height

Area of Science:

• Orthopedic surgery
• Biomechanics
• Surgical planning

Background:

• Posterior tibial slope (PTS) correction is crucial in high tibial osteotomy (HTO).
• Accurate wedge height planning is essential for achieving desired angular correction in ACW-HTO.
• Existing methods for wedge height calculation may introduce errors.

Purpose of the Study:

• To compare the planning precision of three wedge height calculation methods against an angular-based reference for infratubercle ACW-HTO.
• To determine the most accurate method for planning wedge resection in ACW-HTO.

Main Methods:

• Retrospective review of lateral knee radiographs from patients undergoing infratubercle ACW-HTO with PTS ≥ 13°.
• Comparison of three planning methods: osteotomy depth method, fixed ratio 1 (1.2 mm/°), and fixed ratio 2 (1.67 mm/°).
• Angle-based planning served as the reference; correction error defined as wedge height difference; precision assessed using a ±1° threshold.

Main Results:

• The osteotomy depth method achieved a correction error within ±1° in 83% of cases.
• Fixed ratio 1 resulted in a ±1° error in 50% of cases, while ratio 2 had an error in 91% of cases.
• The osteotomy depth method demonstrated superior planning precision compared to fixed ratio methods (p < 0.001).

Conclusions:

• Fixed wedge height ratios lead to significant planning errors in infratubercle ACW-HTO, potentially exceeding ±1° in up to 91% of cases.
• Wedge height calculation based on osteotomy depth and correction angle provides significantly higher planning precision.
• This method is recommended for accurate surgical planning in ACW-HTO procedures.