Podcast Summary: FAI May 2024 Podcast – Discrepancies Between Intraoperative and Postoperative Ankle Motion for Anterior-Approach Total Ankle Arthroplasty

Host: Dr. Charlie Saltzman, Editor, Foot & Ankle International
Guest: Dr. Konstantin Demetrakopoulos, Associate Professor of Orthopedic Surgery, Hospital for Special Surgery, NY
Date: May 7, 2024

Main Theme & Purpose

This episode features an in-depth discussion of Dr. Konstantin Demetrakopoulos’s lead paper published in Foot & Ankle International, which investigates the differences between ankle motion measured during surgery (intraoperatively) versus after surgery (postoperatively) in patients undergoing anterior-approach total ankle arthroplasty (TAA). The conversation explores the study's surprising findings, its clinical implications, and how these insights may influence surgical techniques and patient care.

Key Discussion Points and Insights

Background & Study Rationale (00:03 – 05:15)

• Genesis of the Study:

  • The study originated from an observation by Dr. Rogerio Bitar (Brazil) during his fellowship, who noted an uncertainty in predicting post-op motion based on intraoperative findings.
  • Surgeons commonly debate whether procedures like Achilles lengthening are necessary to preserve or improve ankle motion after TAA.

• Central Question:

  • “What percentage of intraoperative motion achieved during an ankle replacement is maintained at final follow up?” (01:55)
  • Final follow-up defined as when range of motion (ROM) plateaus, based on previous literature (typically around 6 months to 1 year).

Study Design & Major Findings (01:55 – 07:29)

• Methodology:

  • 67 patients with anterior-approach TAA
  • Assessments: Pre-op weight-bearing max flexion/extension X-rays, intraoperative neutral/dorsiflexion/plantar flexion (passive), and post-op follow-up with the same measures.

• Key Results:

  • Dorsiflexion:
    • “Over 90% of patients, if you achieve 10 or 12 or 15 degrees of dorsiflexion intraoperatively, you can expect your patients can maintain that motion at an average of a year after surgery.” (04:39)
  • Plantarflexion:
    • “We actually found that you lose some of that [plantar flexion] motion, more than half of it.” (05:01)
    • Reason likely due to comparing intraoperative passive (supine) and postoperative active (weight-bearing) motion—different biomechanical conditions.
  • Overall ROM:
    • Only modest improvements observed post-op (about 2.5° total arc); no significant gain in dorsiflexion or plantar flexion separately.
    • Significant improvements found only when measuring global (tibiopedal) motion (05:53).

Clinical Implications & Patient Counseling (07:29 – 10:00)

• Expectation Management:

  • “I counsel patients… The reason to do this is to alleviate pain, to preserve the motion you have. Maybe we can get some more range of motion.” (07:48)
  • More improvement in ROM seen in stiffer pre-op patients.

• Loss of Plantar Flexion:

  • Conceded that meaningful plantar flexion loss impacts daily function, such as descending stairs or engaging the calf muscle effectively (09:14).
  • Possible contributing factors:
    • Soft tissue healing, especially anterior capsule/scar formation post-closure.
    • Post-op immobilization protocols versus more immediate knee mobilization post-TKA.

Surgical Factors & Approaches (09:14 – 13:08)

• Incision Technique:

  • Discussion on whether different incisions (e.g., curvilinear anterior or lateral approaches) might mitigate motion loss.
  • Mention of Tim Daniels’ work on a modified anterior approach to reduce wound complications, theorizing it may also allow earlier motion initiation (10:45).

• Practice Change:

  • Study encourages reassessment of when to perform Achilles or gastrocnemius lengthening for increased motion versus deformity correction.
    • “I really have tried to think about this concept of bone resection. How much bone should we be removing, how much bone per individual patient, when to really do a heel cord lengthening, when to do a gastrocnemius recession.” (15:34)

• Bone Resection Considerations:

  • Tensioning soft tissues, bone preservation for potential future revision, restoration of physiologic joint line—all factors influencing surgical decisions (14:15).

• Recent Practice Changes:

  • “I will say that in practice, I’ve been doing fewer heel cord lengthenings since we’ve published this study.” (16:45)

Broader Implications & Call for Research (17:10 – 18:41)

• The Importance of Motion:

  • Motion correlates strongly with patient satisfaction post-TAA.
  • Setting realistic expectations with patients regarding pain relief versus motion gain is crucial. (17:10)

• Research Gaps:

  • Lack of standardized rehab protocols post-TAA.
  • Encouragement for more research on surgical and post-op rehab techniques.
    • “Please do your own research and please do your own studies… What are the surgical techniques? What are the post operative protocols, the rehab protocols?” (17:30)

Notable Quotes & Memorable Moments

• “We’re good at alleviating pain, we can improve function… but almost all studies show a very modest, if any, improvement in the range of motion in the ankle.” – Dr. Demetrakopoulos (02:49)
• “Over 90% of patients, if you achieve 10 or 12 or 15 degrees of dorsiflexion intraoperatively, you can expect your patients can maintain that motion at an average of a year after surgery.” – Dr. Demetrakopoulos (04:39)
• “What holds me back from immediate ankle motion after surgery is I’m worried about the wound healing. Maybe a curvilinear incision would allow earlier range of motion… and that would make a significant difference.” – Dr. Demetrakopoulos (11:10)
• “I will say that in practice, I’ve been doing fewer heel cord lengthenings since we’ve published this study.” – Dr. Demetrakopoulos (16:45)
• “We don’t have a standardized rehab protocol for ankle replacement… how long do we immobilize? When do we begin motion? When do we begin weight bearing? But I truly believe that we need to do more work in this area.” – Dr. Demetrakopoulos (17:35)

Timestamps for Key Segments

| Timestamp | Segment Description | |------------|---------------------------------------------------------------------------| | 00:03 | Introduction to guest and topic | | 01:21 | Study background and rationale | | 04:39 | Key findings: preservation of dorsiflexion, loss of plantar flexion | | 05:53 | Discussion on measurement technique and relevance | | 07:29 | Patient counseling and expectations | | 09:14 | Reasons for loss of plantar flexion, surgical approach considerations | | 12:23 | Impact on clinical practice and decision-making regarding lengthenings | | 15:34 | Bone resection and evolving approach in practice | | 16:45 | Reduction in heel cord lengthenings post-study | | 17:10 | Importance of motion and the need for further research |

Takeaway

This episode reveals that while anterior-approach total ankle arthroplasty reliably preserves intraoperative dorsiflexion, it often does not improve overall ankle range of motion as much as surgeons or patients may hope, with notable loss in plantar flexion. The findings encourage surgeons to re-examine their intraoperative decision-making, postoperative protocols, and the indications for adjunct procedures like tendon lengthening. The call for expanded research and standardization in rehab protocols is clear—a must-listen for any foot and ankle surgeon considering how best to optimize TAA outcomes.