Podcast Summary: FAI June 2024 – Revision Total Ankle Arthroplasty Using the INBONE II System

Podcast: Foot & Ankle International
Host: Charlie Saltzman (Editor, FAI)
Guest: Dr. Jim Diorio (Duke University, Senior Author)
Release Date: June 20, 2024
Lead Paper: Revision Total Ankle Arthroplasty Using the INBONE II System

Overview

This episode features Dr. Jim Diorio, a leading foot and ankle surgeon, discussing his group's extensive experience with the challenging subject of revision total ankle arthroplasty (TAA) using the INBONE II system. The conversation revolves around the results of the largest published cohort to date on revision TAAs, technical pearls, strategies for dealing with complications, and the evolution of ankle arthroplasty implants.

Key Discussion Points & Insights

Study Design and Major Findings

[00:54 – 07:54]

• Scope: Retrospective review of revision total ankle replacements (TARs) (excluding infections) performed at a high-volume center.
• Patient Population: Included patients from all over the U.S., not just local practice.
• Indications for Revision:
  • Implant loosening (most common)
  • Cyst formation (possibly due to temporary polyethylene, possibly improved with vitamin E liners)
  • Polyethylene impingement
  • Subtalar arthritis requiring fusion
  • Excluded infected cases (treated with a staged approach)
• Outcomes:
  • 93% ankle preservation/survival at ~3 years (some patients had shorter follow-up, but were verified to be doing well)
  • 36% complication rate (includes fractures, prosthesis failure, infections, nerve injuries, persistent pain)
  • Comparisons to literature: Previous studies (e.g., Hintermann) reported lower survival rates (~82% at 6 years), but Dr. Diorio anticipates similar or improved medium-term outcomes due to advances in prosthesis technology.

Quote:
“Our results were reasonably good. They were about 93% successful in preserving the ankle... But we did have a relatively high or moderate complication rate of 36%. … One that was the most was actually continued pain.”
– Dr. Jim Diorio [05:50]

Evolution and Design of INBONE II / Envision Systems

[05:10 – 07:50]

• Inspiration & History:

  • The original INBONE and subsequent Envision systems were co-developed by Mark Riley and engineer Mulder.
  • The system allows for different tibial baseplate thicknesses and extended talar components, helping address bone loss and complex revisions.

• Revision-Specific Design:

  • The Envision’s modularity and extended talar fixation are particularly useful in difficult cases (e.g., talonavicular fusion).
  • Quote:
    “The envision is unique because you have multiple thickness of a base for the prosthesis that goes into the tibia, and that allowed you to make up significant loss of bone.”
    – Dr. Jim Diorio [06:26]

• Tibial Fixation Focus:

  • Emphasis on robust tibial fixation; new designs feature extended stems to compensate for “minimal fixation” in some primary implants, which Dr. Diorio believes leads to loosening and need for revision.

Complications and Persistent Pain

[07:54 – 08:06]

• Complication rate: 36% (“moderate”), with persistent pain being the most common issue.
• Theory: Ongoing pain may be due to weak bone and stress at the bone-prosthesis interface, rather than just loosening.
• Other complications: Post-op fractures, prosthesis failure, nerve impingement, infections.

Technical Pearls & Surgical Tips

Medial Malleolar Fixation and Deltoid Release

[08:06 – 12:36]

• Deltoid Release:

  • Introduced by Bonin (France, developer of Salto Talaris).
  • Complete strip from front to back increases stability in varus ankles and decreases need for ligament reconstruction.
  • Diorio claims "hundreds" of such releases without failure.
    • Quote:
      “If you completely strip the medial malleolus of the deltoid, and I mean from front to back...I've never had one fail.”
      – Dr. Jim Diorio [09:37]

• Medial Malleolar Fixation:

  • Commonly fixed with a fully-threaded, cannulated screw (usually 40mm), especially in osteoporotic/soft bone scenarios.
  • Prevents intraoperative fractures, helps with postoperative weight bearing, now common in most revisions.

Alignment Techniques: PSA vs. External Frame

[12:36 – 15:34]

• Use of Patient Specific Alignment (PSA):
  • Recent adopter of PSA (since 2–3 years), but mainly relied on external guide for most revisions in the study.
  • The INBONE system’s external jig typically offers reliable alignment (within 2–3° of varus/valgus).
  • Opened up the ankle and performed Achilles releases early to facilitate guide use.
    • “...The inbone is itself a guide and it gave me a very good guide...So for the vast majority of these, if not all of the revisions that I did using the inbone, I used the external alignment guide.”
      – Dr. Jim Diorio [13:47]

Addressing Revision of Failed INBONE Prostheses

[15:34 – 20:28]

• Approach: Be bone-preserving at all stages.
• Technical Tip:
  • Use a small TPS reciprocating saw vertically to break spot welds and create a minimal window (about 15mm) in the tibia.
  • Use an impactor or a wrench to assist with stem removal, limiting bone loss.
    • “Do not take out a full window to take out the inbone. Use the reciprocating saw, get it loosened up, and then use that technique of putting the wrench on and then hitting the wrench distally, and they all came out.”
      – Dr. Jim Diorio [19:48]

Patient Selection and Contraindications

[20:28 – 23:43]

• Absolute Contraindication: Infection (treat with explant, staged revision with antibiotic spacer).
• Other Considerations:
  • Avascular necrosis (AVN) of talus: If minor, consider Envision; if significant, opt for combined total ankle and total talus replacement.
  • Excessive bone loss: Bone graft as needed, not always necessary to achieve a perfect flat cut.
  • Custom talar implants can be matched to existing components if one side remains stable.

Broader Significance & Clinical Impact

[23:43 – 25:41]

• Function vs. Fusion:
  • Revision TAAs provide better function than fusion (TTC), though both relieve pain. Preserving even slight ankle motion can significantly reduce stress on the subtalar joint and improve quality of life.
  • “...If we can get 5 to 10 degrees only the ankle, then we will reduce the stress on the subtalar joint by 90%. So that's my challenge to you and the audience to complete my goal with that experiment.”
    – Dr. Jim Diorio [25:22]

Advice for Surgeons

[25:49 – 27:11]

• Experience Matters:

  • Surgeons should have experience with at least 10 primary INBONE procedures before attempting revisions.
  • Familiarity with the modular Envision components is highly recommended.
  • In most revision cases (unless faced with major loss of bone or infection), consider revision arthroplasty before fusion.

• Innovation:

  • Emerging strategies like combining custom talar components with familiar tibial hardware are promising.

Memorable Quotes & Moments

• “I have done about 1600 total ankles in my life...Consequently we get to do more revisions than most people.”
  – Dr. Jim Diorio [01:04]
• “Deltoid release... I've done hundreds of them and I've never had one fail.”
  – Dr. Jim Diorio [09:37]
• “I would tell people that you need experience with the primary inbone. So if you want to do revision inbones, then I would certainly do at least 10 inbones before you embark on that.”
  – Dr. Jim Diorio [25:49]
• “The envision is unique... designed for revision. One of the few ankles that that's been the case.”
  – Dr. Jim Diorio [06:26]
• “Do not take out a full window to take out the inbone... And then use that technique of putting the wrench on and then hitting the wrench distally, and they all came out.”
  – Dr. Jim Diorio [19:48]

Timestamps for Key Segments

• Overview and Paper Summary: 00:54 – 07:54
• Technical Pearls (Medial Malleolus/Deltoid): 08:06 – 12:36
• Alignment and PSA: 12:36 – 15:34
• Removing a Failed INBONE: 15:34 – 20:28
• Patient Selection: 20:28 – 23:43
• Clinical Impact & Future Study Goals: 23:43 – 25:41
• Advice for Surgeons/Final Thoughts: 25:49 – 27:11

Summary Prepared by:
Podcast Summarizer (Expert)
For listeners who want a rich, detailed walkthrough of revision total ankle arthroplasty using the INBONE II system, this episode provides unmatched real-world insight, technical pearls, and strategic guidance directly from one of the field’s most experienced practitioners.