Higher precision and better alignment: infra- vs retro-tubercle slope-reducing HTO

Introduction

High tibial osteotomy (HTO) is a well-known procedure for patients with knee deformities, especially when there is varus alignment, medial compartment overload, or excessive posterior tibial slope (PTS). Surgeons often aim not only to correct the slope but also to preserve or optimize frontal (varus/valgus) alignment.

A recent study (Patel et al., 2025) adds important insight: comparing two techniques of slope-reducing HTO — infra-tubercle vs retro-tubercle osteotomy — they assess whether one technique offers more precise slope correction while maintaining frontal plane alignment better than the other.

This is relevant for surgeons who want to ensure both sagittal and coronal control in HTO, minimize unintended alignment shifts, and improve the predictability of outcomes.

What was done

1. The study compared two HTO techniques in slope reduction:

1. 1. Infra-tubercle: the osteotomy is made below the tibial tubercle.
   2. Retro-tubercle:  osteotomy behind or proximal to the tubercle.
      
      
2. Key outcomes measured:
   
   
   1. How closely the actual postoperative slope matched the planned/desired slope (i.e., precision of slope change).
   2. How much the frontal plane alignment (varus/valgus) was preserved (avoidance of unintended drift).
      
      
3. Statistical comparison between the two surgical techniques to see which method achieves better results in these metrics.
   
   

Key findings

• Higher precision: The infra-tubercle technique produced smaller deviations between planned and achieved posterior tibial slope. In other words, surgeons could better “hit” their target slope reduction.
  
  
• Better frontal alignment preservation: Using the infra-tubercle method led to fewer deviations in the coronal (frontal) plane — less unintended varus or valgus after surgery — compared with retro-tubercle.
  
  
• Overall, infra-tubercle slope-reducing HTO seems to give a more predictable result for both slope and frontal alignment.
  
  

Why this matters

• Surgical precision is crucial. If slope correction is imprecise or if the frontal alignment is altered inadvertently, the patient may experience suboptimal biomechanical loading, risk of early osteoarthritis, instability, or need for revision.
  
  
• Many techniques focus on either correcting slope or correcting varus/valgus, but achieving both safely and predictably is technically challenging. The findings suggest that infra-tubercle HTO might reduce some of those risks.
  
  
• For surgeons planning slope-reducing osteotomies (for example, in patients with combined varus + high posterior slope, or patients at risk for ACL graft failure), choosing the infra-tubercle approach could improve outcomes.
  
  

  Limitations & open questions

• The study seems to focus on radiographic alignment and precision. Functional outcomes (pain, mobility, long-term joint survival) are not the primary endpoints. We don’t yet know how these radiographic advantages translate into patient-centered results over longer follow-ups.
  
  
• Surgical technique, surgeon experience, and patient anatomy (bone shape, soft-tissue envelope) could influence how easy or reliable one method is. These factors may limit generalizability.
  
  
• Possible trade-offs: Does infra-tubercle osteotomy require more complex exposure, increased risk to certain structures, or more demanding fixation? These aspects need evaluation.
  
  
• Follow-up time: whether any drift in alignment or slope occurs over time (due to bone remodeling, fixation loosening, etc.).
  
  

• Clinical take-home

  If you are a surgeon considering slope-reducing HTO, the infra-tubercle technique appears to offer better precision in achieving the planned slope and less risk of unintended change in frontal plane alignment compared to retro-tubercle.

  
  When planning, consider:

  • Preoperative imaging and planning to set both slope and coronal alignment goals.
  • Use the infra-tubercle approach, especially when controlling unintended frontal plane changes is critical.
  • Monitor your postoperative radiographs closely; measure how close slopes are to planned, and observe coronal alignment shifts.