THE GUIDEWIRE · CLASSROOM SERIES
TMT SLIPPAGE
~ a fellowship-level brief ~
SUBJECT:HVA Surgery · Post-op TMT pain
TOPIC:Distal osteotomy failure modes
DATE:2026
— page 01 —
1
∙ Lesson 1 ∙

What this is.

"TMT slippage" is the working term — half clinical jargon, half newly-published nomenclature — for post-operative subluxation, widening, or symptomatic instability at the first tarsometatarsal joint after a distal metatarsal osteotomy (DMO) for hallux valgus correction.

You fix the bunion distally. The head looks great on the table. Six weeks later the patient points proximally — to the dorsal midfoot, roughly 3–4 cm above the bump — and says "this is what hurts now."

FORMAL DEFINITION (LALEVÉE 2024, WBCT)
The transverse-plane lateral distance between the most lateral aspect of the medial cuneiform and the 1st metatarsal base — measured at the dorsal, central, and plantar thirds of the TMT joint on axial weightbearing CT — that increases from preoperative to postoperative state.

The term is new (third-generation MIBS literature, ~2022–2024). The phenomenon is old. Lapidus wrote about it in 1934. We just have better imaging now to see it happen.

📌 Heads up on the term: "TMT slippage" is not in McGlamry's. It's not in Coughlin/Mann. The published equivalents are "1st TMT joint subluxation," "loss of correction at the first TMT," and "symptomatic first-ray instability after distal HV correction." Use it as shorthand — but cite the underlying concept.
— page 02 —
2
∙ Lesson 2 ∙

Why it matters.

Because the most common reason a bunion surgery "fails" isn't the surgery — it's choosing the wrong operation for the wrong foot.

The TMT slippage concept is really a patient-selection concept. It forces the question every resident should ask in clinic before drawing the consent form: where is the apex of this deformity, and can my chosen procedure actually correct it there?

★ Stakes for the patient
Persistent midfoot pain · loss of correction · transfer metatarsalgia · recurrence of the bump · return to the OR for a Lapidus salvage that could have been the index procedure.
— page 03 —
3
∙ Lesson 3 ∙

Four mechanisms.

Memorize these. They overlap. They co-exist. They explain virtually every case of post-DMO TMT pain you'll ever see.

  1. 1 Pre-existing instability unmasked. The deviated hallux + bowstrung lateral structures were hiding a lax TMT. Once you re-seat the sesamoids and align the ray, ground reactive force transmits straight up a column that can't tolerate it. Hansen's "first ray as a single dynamic unit."
  2. 2 Wrong-level correction (CORA mismatch). If the apex of deformity is at the TMT, a distal cut is biomechanically eccentric. The long lever arm of metatarsal shaft above the osteotomy drifts back into varus. Capsular fatigue follows. McCabe et al. identify the TMTJ1 as the CORA of HV.
  3. 3 The MIBS levering effect. Lalevée 2024 on WBCT: the extreme lateral translation of the capital fragment in 3rd-gen MIS bunionectomy, plus adduction of the residual shaft, mechanically pushes the metatarsal base laterally relative to the medial cuneiform — measurable widening even in feet without preop instability.
  4. 4 Frontal-plane under-correction. Dayton, Campbell, Kim, de Cesar Netto: HV is triplanar. A translational osteotomy that doesn't derotate leaves a pronated first ray and persistent abnormal medial-column loading.
FLOW: Deformity hides TMT laxity → distal correction reduces the bump → ground forces now transmit through a deficient TMT → capsule fatigues, transverse widening, dorsal-medial subluxation → pain, recurrence, or both
— page 04 —
4
∙ Lesson 4 ∙

The hypermobility debate.

You cannot understand TMT slippage without understanding the century-long argument about whether first-ray hypermobility is a real disease entity. This is fellowship-board material.

"It's REAL"
  • Morton 1928, 1935 — original concept
  • Lapidus 1934 — atavistic 1st MTC = root cause of HV
  • Sangeorzan & Hansen 1989 — modernized Lapidus
  • Hansen 2000 — Lapidus first for most HV
  • Dayton et al. 2013–14 — triplanar pronation at TMT
  • Ellington et al. — 96% of recurrent HV had clinical hypermobility
"It's a CONSEQUENCE"
  • Coughlin & Jones 2007 (JBJS) — Klaue dropped 7.2 → 4.5mm after proximal osteotomy + soft tissue, no TMT fusion
  • Plantar gapping resolved in 1/3 of feet without arthrodesis
  • Doty & Coughlin 2013 — "facts and fiction"
  • Faber: TMT contributes 82% of medial / 57% of dorsal 1st-ray motion → it's normal
  • Campbell 2021 WBCT — pronation may be intrinsic metatarsal torsion a Lapidus can't fix
✏️ Where the field has landed (2020–2025): Hypermobility is real but multiplanar. Sagittal-only Klaue testing is inadequate. WBCT metrics (intercuneiform distance, plantar gapping, TMT axial widening) are better. Most relevant when severe, recurrent, or with adductus / planovalgus.
— page 05 —
5
∙ Lesson 5 ∙

Don't pick DMO if...

The high-yield list of red flags that should push you toward a Lapidus (or proximal procedure) instead of a distal-only correction.

★ Pearl from Kaufmann
Distal Chevron reliably corrects ~6.5° of IMA. That's it. If you need more than that, you are asking the wrong operation to do work it cannot do.
— page 06 —
6
∙ Lesson 6 ∙

Workup of post-op TMT pain.

History. Persistent or worsening dorsomedial midfoot pain weeks-to-months after an initially successful bunionectomy. Pain with push-off. Recurrence of the bump.

Exam.

Imaging.

→ Weightbearing AP/lat/sesamoid axial: IMA recurrence, plantar gapping (lat), sesamoid station, hardware position, TMT joint-space changes.
→ Weightbearing CT = standard of care. Quantifies transverse TMT widening, intercuneiform distance, frontal-plane pronation (alpha angle, sesamoid rotation), subtle arthritic change.
→ MRI if hardware permits — capsulitis, BME, stress reaction, neuroma.
★ THE SINGLE MOST USEFUL TEST
Diagnostic intra-articular 1st TMT injection (lidocaine ± steroid, under fluoro or US). If pain disappears, the TMT is the generator. If it doesn't, look elsewhere — shaft, neuroma, MTP, hardware.

Differential. 1st TMT OA · symptomatic instability without OA · painful retained hardware · sural/DM cutaneous neuroma · 2nd met stress reaction · dorsal malposition of the capital fragment · transfer metatarsalgia · recurrent HV with bursitis · AVN of the head (esp. after aggressive lateral release or scarf).

— page 07 —
7
∙ Lesson 7 ∙

When salvage is needed.

Conservative first (4–6 months, unless clearly mechanical):

🔧 The workhorse salvage: Modified Lapidus arthrodesis. The landmark paper is Coetzee, Resig, Kuskowski, Saleh — JBJS 2003;85:60–65 — "The Lapidus Procedure as Salvage After Failed Surgical Treatment of Hallux Valgus."

→ 77% very satisfied · 4% satisfied · 19% somewhat satisfied · 0 hallux varus · 3 nonunions (all smokers) · 0 recurrences.

Know this paper. Cite this paper.

Alternatives & adjuncts:

DECISION RULE: WBCT shows TMT widening or plantar gapping > 2mm change from postop baseline + diagnostic injection localizes pain to the TMT + conservative care has failed at 3–4 mo → revision modified Lapidus arthrodesis with takedown of the prior osteotomy.
— page 08 —
8
∙ Lesson 8 ∙

Pitfalls.

High-yield mistakes that get residents in trouble — and on oral boards.

— page 09 —
9
∙ Lesson 9 ∙

Pearls.

The things you write down once, and remember for ten years.

★ #1 — The CORA principle
Correction belongs at the apex of deformity. If the apex is the TMT, correcting at the head is the surgical equivalent of patching drywall when the foundation has shifted.
★ #2 — Patient selection > technique
TMT slippage is overwhelmingly a failure of selection, not execution. The resident who screens for instability, pronation, sesamoid station, and adductus before choosing the operation sees this complication far less.
★ #3 — WBCT changes the conversation
If you only have plain films, you are missing transverse TMT widening, frontal-plane pronation, and subtle subluxation. The 2024 Lalevée paper exists because WBCT made it visible.
★ #4 — The injection is your friend
Confused about whether the pain is TMT vs. neuroma vs. hardware vs. shaft? Inject the joint. Twenty minutes later you'll have your answer.
★ #5 — Coetzee 2003 is the salvage paper
Lapidus rescues failed distal HV surgery with high satisfaction. Know the numbers. Cite it on rounds. Use it in your consent discussion.
★ #6 — Term is emerging, concept is old
"TMT slippage" is 2024 vocabulary for a 1934 idea. Don't get caught defending the name on oral boards — defend the underlying biomechanics.
— page 10 —
10
∙ Editor's marginalia ∙

Confidence & sources.

CONFIDENCE LEVEL — 7 / 10
Strong: the underlying biomechanics (Lapidus rationale, Coughlin/Jones data, Coetzee salvage outcomes, recurrence predictors).
Evolving: the specific term "TMT slippage" and WBCT-based thresholds — these are 2024 literature, not yet settled.
Debated: whether isolated first-ray hypermobility is a discrete entity (Coughlin vs. Hansen schools).

∙ Sources ∙

∙ ∙ ∙ END OF NOTES ∙ ∙ ∙
CLASSROOM EDITION
— Peter Sorensen, DPM
THE GUIDEWIRE · soleintell.com
AI-assisted research and composition. Educational use only.
Not a substitute for individualized clinical judgment, peer-reviewed literature, or attending guidance.
Verify locally before applying any concept to a real patient.
Terminology around "TMT slippage" is emerging and not yet uniform across the literature.
© 2026 PETER SORENSEN, DPM