FAI October 2024 Podcast: The Role of the Flexor Hallucis Longus in the Treatment of the Painful Hallux Metatarsophalangeal Joint

Podcast Summary

Overview

Episode Title: The Role of the Flexor Hallucis Longus in the Treatment of the Painful Hallux Metatarsophalangeal Joint
Podcast: Foot & Ankle International
Host: Dr. Charlie Saltzman, Editor, FAI
Guest: Dr. Jim Mickelson, Professor of Orthopedics and Rehabilitation, University of Vermont
Air Date: October 25, 2024

This episode features an in-depth discussion with Dr. Jim Mickelson about his team's 10-year study on the flexor hallucis longus (FHL) and its pivotal role in diagnosing and treating pain and pathology in the hallux metatarsophalangeal (MTP) joint. The conversation challenges traditional approaches, highlights often-missed diagnoses, and explores nonoperative and operative strategies with practical, evidence-based recommendations.

Key Discussion Points and Insights

Study Background & Main Findings

Clinical Inspiration:
Dr. Mickelson recounts seeing patients with unexplained big toe (hallux) pain, ultimately realizing overlooked FHL pathology was significant.

"It's like a lot of other things … everyone kept saying it was medial deltoid injury until [Ken Johnson] identified it. And then all of a sudden you could see it." — Dr. Mickelson [02:52]
Study Overview:
- 10-year review of patients with painful hallux MTP joints at the University of Vermont [00:56].
- Identified FHL stenosis as a major, underdiagnosed cause.
- Most patients improved with nonoperative, targeted FHL stretching.
- Of the small subset requiring surgery, isolated FHL release (not at the toe) led to nearly universal resolution.
"18 out of those 20 people completely cured. One person got a little worse, one person stayed about the same." — Dr. Mickelson [03:46]

Biomechanical Link Between FHL and Hallux MTP Pain

Cadaver Study:
Collaborated with Neil Sharkey to show, through biomechanical cadaver modeling, that minor FHL restriction (as little as 2mm) significantly increased damaging dorsal joint forces at the first MTP.

"…even if you restricted the motion by as little as 2 millimeters, that it increased the forces inside the first MTP joint significantly." — Dr. Mickelson [06:27]
Clinical Relevance:
Provides a mechanistic explanation for isolated arthritis at the first MTP joint—no similar findings at other MTPs [07:42].
- Suggests FHL stiffness contributes directly to pathogenesis.

Reframing Surgical Thinking

Traditional Surgeries vs. FHL Focus:
- Explains that surgical procedures like shortening osteotomies, or dorsal cheilectomy, may inadvertently alleviate FHL tension [08:46].
- Emphasizes that explicit FHL lengthening or release may be the real reason many traditional surgeries offered relief.
"…doing the shortening, osteotomies, all the other fancy stuff, basically, functionally are lengthening the FHL." — Dr. Mickelson [09:28]

Prevalence and Patient Assessment

Bilateral Presence, Unilateral Symptoms:
- About 50% of all patients showed evidence of FHL tightness, half of them bilaterally, but most had symptoms on only one side [09:58].
"…50% of everybody had evidence of tight FHLs without symptoms… of those 50%, 50% of those were bilateral. …the majority of them, it's just the one side." — Dr. Mickelson [10:20]

Imaging and Diagnostic Tools

Role of MRI:
- MRIs rarely reveal FHL pathology, even when present—radiologists often miss it [13:19].
- MRIs primarily used to rule out alternative diagnoses (e.g., ganglion cysts) or when clinical findings are ambiguous.
- Plain films are essential to assess for os trigonum involvement [13:58].

Nonoperative vs. Operative Management

Isolated FHL Stretching:
- First-line and highly effective; standardized stretching protocol provided in the published study [18:11].
- Key is patient compliance—education and demonstration are vital.
"Two things we do for everyone is give everyone an instruction sheet … and then I walk through it with them personally and show them…" — Dr. Mickelson [18:12]
Open vs. Endoscopic FHL Release:
Dr. Mickelson strongly favors open, above-tarsal-tunnel approach:
- Faster (3 min tourniquet time for standard, 6 min with os trigonum removal), supine position, fewer complications (notably, avoids sural nerve injuries more common in endoscopic).
- Comparable recovery, lower complication rates, and cost.
"It is a slam dunk. So I wholeheartedly vote for open. I love the scope. I do scopes for other things, but not for this." — Dr. Mickelson [17:24]

Stretching Protocol Details

Described Protocol:
- Place a small book (~½ inch) under big toe, just distal to MTP joint, passively dorsiflexing it.
- Foot flat, knee bent, perform Achilles stretch while keeping ball of foot and heel on ground.
- Hold for 30 seconds, 3 reps, several times daily [19:20].
"…foot flat on the ground and you do an Achilles stretch with your knee bent. …hold it for a count of 30, stand up straight three times in a row, a couple times a day." — Dr. Mickelson [19:28]

Unrecognized and Delayed Diagnosis

High Frequency of Missed Cases:
- Average diagnostic delay originally 7 years per patient; has improved, but still up to 30% experience a delay of two years [20:09].
- Emphasizes importance of clinician awareness and early, simple intervention.
"…It's an easy diagnosis to make and an easy diagnosis to treat." — Dr. Mickelson [20:49]

Notable Quotes & Memorable Moments

On Eye-Opening Nature of FHL Pathology:

"It's seen me, but I haven't seen it, as you said." — Dr. Saltzman [09:39]
On Shifting Paradigms:

"If we can get in front of this, we potentially have… a way to prevent [progression]. So I think that's pretty cool." — Dr. Mickelson [20:56]

Important Segment Timestamps

[00:56] – Dr. Mickelson’s summary of the 10-year study & clinical observations
[05:18] – Biomechanical data linking FHL tightness to increased MTP joint forces
[08:46] – Explaining why some traditional surgeries likely work: role of FHL
[09:58] – Data on prevalence and bilaterality of FHL tightness
[13:19] – On (limited) use of MRI and reliance on clinical assessment
[14:40] – Open vs. endoscopic FHL release: technical and practical considerations
[18:11] – Detailed description of patient FHL stretching instructions
[20:09] – Impact of missed diagnosis and evolving clinical awareness

Takeaways

FHL stenosis is a common, underdiagnosed cause of hallux MTP joint pain, often mistaken for primary joint pathology.
Nonoperative management with directed FHL stretching is highly effective and should be first-line.
Simple, open FHL release is effective in refractory cases—often superior to endoscopic methods.
Early recognition can prevent unnecessary surgeries and potentially halt arthritis progression.

Podcast Summary

Overview

Key Discussion Points and Insights

Study Background & Main Findings

Clinical Inspiration:
Dr. Mickelson recounts seeing patients with unexplained big toe (hallux) pain, ultimately realizing overlooked FHL pathology was significant.

"It's like a lot of other things … everyone kept saying it was medial deltoid injury until [Ken Johnson] identified it. And then all of a sudden you could see it." — Dr. Mickelson [02:52]
Study Overview:
- 10-year review of patients with painful hallux MTP joints at the University of Vermont [00:56].
- Identified FHL stenosis as a major, underdiagnosed cause.
- Most patients improved with nonoperative, targeted FHL stretching.
- Of the small subset requiring surgery, isolated FHL release (not at the toe) led to nearly universal resolution.
"18 out of those 20 people completely cured. One person got a little worse, one person stayed about the same." — Dr. Mickelson [03:46]

Biomechanical Link Between FHL and Hallux MTP Pain

Cadaver Study:
Collaborated with Neil Sharkey to show, through biomechanical cadaver modeling, that minor FHL restriction (as little as 2mm) significantly increased damaging dorsal joint forces at the first MTP.

"…even if you restricted the motion by as little as 2 millimeters, that it increased the forces inside the first MTP joint significantly." — Dr. Mickelson [06:27]
Clinical Relevance:
Provides a mechanistic explanation for isolated arthritis at the first MTP joint—no similar findings at other MTPs [07:42].
- Suggests FHL stiffness contributes directly to pathogenesis.

Reframing Surgical Thinking

Traditional Surgeries vs. FHL Focus:
- Explains that surgical procedures like shortening osteotomies, or dorsal cheilectomy, may inadvertently alleviate FHL tension [08:46].
- Emphasizes that explicit FHL lengthening or release may be the real reason many traditional surgeries offered relief.
"…doing the shortening, osteotomies, all the other fancy stuff, basically, functionally are lengthening the FHL." — Dr. Mickelson [09:28]

Prevalence and Patient Assessment

Bilateral Presence, Unilateral Symptoms:
- About 50% of all patients showed evidence of FHL tightness, half of them bilaterally, but most had symptoms on only one side [09:58].
"…50% of everybody had evidence of tight FHLs without symptoms… of those 50%, 50% of those were bilateral. …the majority of them, it's just the one side." — Dr. Mickelson [10:20]

Imaging and Diagnostic Tools

Role of MRI:
- MRIs rarely reveal FHL pathology, even when present—radiologists often miss it [13:19].
- MRIs primarily used to rule out alternative diagnoses (e.g., ganglion cysts) or when clinical findings are ambiguous.
- Plain films are essential to assess for os trigonum involvement [13:58].

Nonoperative vs. Operative Management

Isolated FHL Stretching:
- First-line and highly effective; standardized stretching protocol provided in the published study [18:11].
- Key is patient compliance—education and demonstration are vital.
"Two things we do for everyone is give everyone an instruction sheet … and then I walk through it with them personally and show them…" — Dr. Mickelson [18:12]
Open vs. Endoscopic FHL Release:
Dr. Mickelson strongly favors open, above-tarsal-tunnel approach:
- Faster (3 min tourniquet time for standard, 6 min with os trigonum removal), supine position, fewer complications (notably, avoids sural nerve injuries more common in endoscopic).
- Comparable recovery, lower complication rates, and cost.
"It is a slam dunk. So I wholeheartedly vote for open. I love the scope. I do scopes for other things, but not for this." — Dr. Mickelson [17:24]

Stretching Protocol Details

Described Protocol:
- Place a small book (~½ inch) under big toe, just distal to MTP joint, passively dorsiflexing it.
- Foot flat, knee bent, perform Achilles stretch while keeping ball of foot and heel on ground.
- Hold for 30 seconds, 3 reps, several times daily [19:20].
"…foot flat on the ground and you do an Achilles stretch with your knee bent. …hold it for a count of 30, stand up straight three times in a row, a couple times a day." — Dr. Mickelson [19:28]

Unrecognized and Delayed Diagnosis

High Frequency of Missed Cases:
- Average diagnostic delay originally 7 years per patient; has improved, but still up to 30% experience a delay of two years [20:09].
- Emphasizes importance of clinician awareness and early, simple intervention.
"…It's an easy diagnosis to make and an easy diagnosis to treat." — Dr. Mickelson [20:49]

Notable Quotes & Memorable Moments

On Eye-Opening Nature of FHL Pathology:

"It's seen me, but I haven't seen it, as you said." — Dr. Saltzman [09:39]
On Shifting Paradigms:

"If we can get in front of this, we potentially have… a way to prevent [progression]. So I think that's pretty cool." — Dr. Mickelson [20:56]

Important Segment Timestamps

[00:56] – Dr. Mickelson’s summary of the 10-year study & clinical observations
[05:18] – Biomechanical data linking FHL tightness to increased MTP joint forces
[08:46] – Explaining why some traditional surgeries likely work: role of FHL
[09:58] – Data on prevalence and bilaterality of FHL tightness
[13:19] – On (limited) use of MRI and reliance on clinical assessment
[14:40] – Open vs. endoscopic FHL release: technical and practical considerations
[18:11] – Detailed description of patient FHL stretching instructions
[20:09] – Impact of missed diagnosis and evolving clinical awareness

Takeaways

FHL stenosis is a common, underdiagnosed cause of hallux MTP joint pain, often mistaken for primary joint pathology.
Nonoperative management with directed FHL stretching is highly effective and should be first-line.
Simple, open FHL release is effective in refractory cases—often superior to endoscopic methods.
Early recognition can prevent unnecessary surgeries and potentially halt arthritis progression.

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Summary

Podcast Summary

Overview

Key Discussion Points and Insights

Study Background & Main Findings

Biomechanical Link Between FHL and Hallux MTP Pain

Reframing Surgical Thinking

Prevalence and Patient Assessment

Imaging and Diagnostic Tools

Nonoperative vs. Operative Management

Stretching Protocol Details

Unrecognized and Delayed Diagnosis

Notable Quotes & Memorable Moments

Important Segment Timestamps

Takeaways

Further Reading

Summary

Podcast Summary

Overview

Key Discussion Points and Insights

Study Background & Main Findings

Biomechanical Link Between FHL and Hallux MTP Pain

Reframing Surgical Thinking

Prevalence and Patient Assessment

Imaging and Diagnostic Tools

Nonoperative vs. Operative Management

Stretching Protocol Details

Unrecognized and Delayed Diagnosis

Notable Quotes & Memorable Moments

Important Segment Timestamps

Takeaways

Further Reading