61 - HAV 1 Flashcards
1
Q
Introduction
A
- Bunions are a huge part of what we do – all day every day you will see this
- Covering all of bunion treatment is a daunting task
- I want you to be aware of what has been held tried and true in regards to bunion surgery in the eyes of many podiatrists, but what may not be evidence-based
- Some ideas that we will talk about today will be contradictory to what has been engrained
- It takes roughly 17 years for new evidence to become mainstream, so while new ideas are gaining steam, it is not mainstream currently
- New ideas will not be on your board exams and asked in clinical rotations for another 17 years
- I want you to be able to critically think about the evidence presented and form own opinions
- When I am talking about “old” versus “new” – I am not saying those who are doing old procedures are bad surgeons, I’m just saying that it is hard to change habit
- Until 2-3 years ago, bunion surgery was not a highlight of lecture series – many of them were based on complications (hallux varus and recurrence)
- Now we are seeing exciting engagement and discussion of bunions – are we best treating this?
- We will spend a lot more time talking about the concepts of bunion surgery, but not a lot of time talking about the step-by-step memorization of the procedures
- Make sure you review your surgical text on all of your bunion procedures – GERBERT
- When you are reviewing the surgical procedures, do not focus on exactly how you do the procedure, focus on the big picture
- If I have a low IM angle, what type of procedure do I do? What about a high IM angel? – Focus on this, not how you hold the saw blade, etc.
2
Q
Bunion terminology
A
- Evolution of terminology has progressed in parallel with our changing understanding of the deformity itself
- Multiple terms exist, sometimes with multiple meanings
- Inconsistencies in interpretation can lead to confusion
3
Q
Bunion (Durlacher 1845)
A
- Inflammation of the synovial bursa of the great toe, resulting in enlargement of the joint and lateral displacement of the toe
4
Q
Hallux valgus (Heuter 1877)
A
- The distal portion of the great toe (hallux) is deviated away from the midline of the body (valgus)
- This descriptor refers to the transverse plane in the foot (historical perspective)
5
Q
Valgus confusion
A
- Transverse plane valgus
- Frontal plane valgus
6
Q
Hallux abducto valgus (1970)
A
- The great toe (hallux) is deviated away from the midline of the body in the transverse plane (abducto) and rotated away from the midline of the body in the frontal plane (valgus)
- *Tri plane description uses frontal plane definition of Valgus
7
Q
Metatarsus primus varus (Truslow 1925)
A
- The distal portion of the first metatarsal (metatarsus primus) is deviated toward the midline of the body (varus)
- This descriptor refers to the transverse plane in the foot
- So “varus” means toward midline, NOT inverted in frontal plane
- ***Name Change to Highlight the True Level of the Deformity
8
Q
Tri-axial orthogonal coordinate plane
A
- Justifies the frontal plane definition of Valgus used in the term HAV
- It uses transposition of the three cardinal planes used in the leg to the foot
- There is a change in designations of the three planes due to 90 degree
post embryologic rotation - Using this system Varus and Valgus are more appropriate frontal plane
descriptors than transverse plane descriptors in the foot
9
Q
Coronal plane
A
- So, the transverse and sagittal planes are clear, what about the frontal???
- We have not historically talked about any significant research into the frontal plane
- No one has continued to stick with frontal plane research
- It is NOT well understood that there is frontal plane movement, but it has not been incorporated into treatment
10
Q
Multiplanar 1st metatarsal position
A
- Range of Motion studies of the first ray create assumptions of position in a bunion
- Hicks
11
Q
Hick’s orientation
A
o This creates inversion-dorsiflexion and gives the impression that the metatarsal is in a z-axis varus position in a bunion
o Found this from 5 cadavers and manipulated them – this is what our idea is based on
12
Q
Tri-Plane Motion of the First Ray – Which way does it rotate?
A
o Adduction, Dorsiflexion, Inversion
o (Metatarsus Primus Varus(frontal))
13
Q
Alternate observations to Hicks
A
o Adduction, Dorsiflexion, Eversion
o Metatarsus Primus Valgus
14
Q
Dorsiflexion-inversion
A
WRONG
- Hicks
15
Q
Dorsiflexion-eversion
A
All current research
16
Q
Circumstantial association
A
- These studies all pursued understanding of the Normal ROM of the first ray
- Normal Range of motion is just that… Normal!
- Normal tells us nothing of what the metatarsal position is in the deformed foot.
- Even it were acceptable to apply normal ROM to deformity position, the lack of consensus in first ray ROM is enough to prevent the practice
17
Q
Accurate terminology
A
- Use of the tri-axial orthogonal coordinate plane system to promote clarity in conversation.
- Accurate anatomic description of deformity in multiple planes to keep in the mind of the surgeon the complete nature of the deformity for appropriate planning.
18
Q
Hallux Abducto Valgus
A
o Describes great toe segment of deformity
o Uses tri-axial orthogonal coordinate system
o Describes multi-planar position
19
Q
Metatarsus Primus Adducto Valgus
A
o Describes metatarsal segment of deformity
o Uses tri-axial orthogonal coordinate system
o Describes multi-planar position
20
Q
Summary
A
- There is a diversity of terms used to describe a bunion
- Use of the tri-axial orthogonal coordinate system and associated terms provides clarity in conversation
- Multi-planar position should be described to aid the surgeon in planning correction
- Bunion description: Hallux Abducto Valgus with Metatarsus Primus Adducto Valgus
21
Q
Axial studies
A
- Let’s look at the evidence on the frontal plane position of the 1st Met in a bunion….
- Normal feet – Rectus position
- Bunion feet – Valgus position
- This is important because it leads to the surgical approach
22
Q
Coronal plane observation
A
- Valgus metatarsal rotation (pronation) has been shown to be consistent in HAV
23
Q
Literature findings on coronal plane observations
A
- Scranton. CORR 1980: Feet with Bunions averaged 14.5 degrees of eversion of the first metatarsal, 3.1 normal
- Talbot & Saltzman, FAI 1998: Pronation of metatarsal and subluxation
- Mortier. Orthop Traumatol Surg Res. 2012: Feet with Bunions have everted first metatarsals
- Okuda, JOS 2009, 2013: Supination improved correction of sesamoids
- Dayton, Feilmeier, Kauwe 2013, 2014, 2015: Direct correlation of PASA & TSP to pronation of the first metatarsal in frontal plane
- Kim FAI 2015: WB CT evaluation showing metatarsal pronation in HAV (87.3%) vs. control
24
Q
Pronation of the first metatarsal is the THIRD plane of the deformity
A
- Metatarsus Primus Adducto Valgus
- Top: sesamoids are relatively parallel to the WB surface = no bunion
- Middle: sesamoids and met are slightly rotated = bunion present
- Bottom: sesamoids and met are severely rotated = severe bunion
25
Correlation of bunion severity and frontal plane rotation
- Left: tibial sesamoid position is normal (2-3), complex of metatarsal and sesamoids are parallel to the WB surface, so normal
- Middle: starting to see bunion (4 – midline), slight valgus rotation of met + sesamoid complex
- Left: bunion present, tibial sesamoid is 6, significant rotation of met + sesamoid complex
26
Sesamoid position
- We see the sesamoids as displaced , however they are in fact aligned and in their grooves on a pronated metatarsal in many cases
- This fact changes the anatomic basis of bunion correction
- If sesamoids are in fact in their grooves, then soft tissue balancing cannot provide alignment
- The real solution requires addressing the rotation
- NOTE: if we are going to be doing surgery on a patient, we should be trying our best to restore the normal anatomy as best as possible – this is the patient expectation
27
Example of sesamoid position
- You can see the change in sesamoid position real time after frontal plane rotation without opening the MTPJ
- Rotation dramatically changes all components of MTPJ alignment
- This is intraoperative – tibial sesamoid position is initially a 5
- When we rotate the 1st metatarsal in a valgus direction, the
tibial sesamoid position worsens
- Then we rotate the 1st metatarsal in a varus direction, the
tibial sesamoid position is improved
28
Kim Study (2015)
- A new measure of tibial sesamoid position in hallux valgus in relation to the coronal rotation of the first metatarsal in CT scans
- This study did WB CT scans and found that 87% of patients with a bunion had pronation and eversion of the 1st metatarsal and sesamoids
- Some patients did in fact have subluxation of the sesamoids, but this typically happens in a very high IM angle in a long-standing deformity
- ***SUMMARY: most patients with a bunion are in PRONATION with or without subluxation of the sesamoids***
29
Lamo-Espinosa Study (2016)
- The metatarsal is everted or pronated in the deformity
- The goal is to restore “NORMAL” neutral coronal rotation
- This study looked at NORMAL, non-bunion feet and found that 100% had a tibial sesamoid position of grade 0 (position relative to the 1st metatarsal head)
- This means that if we are doing surgery, we need to be trying to get back to normal – TSB of 0
30
Why is this important?
- Ramdass 2010 & Agrawal 2011 showed that the distance of the sesamoids to the second Met does not change. This highlights the need to reposition the metatarsal over the sesamoids
- Failure to correctly position the metatarsal head in the frontal plane during bunion correction leaves deforming force vectors intact
31
Dayton, Feilmeier Study (2014)
- Observed Changes in Radiographic Measurements of the First Ray Following Frontal Plane Rotation of the First Metatarsal in a Cadaveric Foot Model.
- ***The first metatarsal is not supinated(varus) in a bunion deformity, despite what we have been told by Hicks’ axis definition***
32
How do we recognize pathology on an AP radiograph?
- ***Lateral rounding of metatarsal head - This means that the lateral aspect of the 1st metatarsal head, which is actually the plantar aspect of the metatarsal, is coming into view due to frontal plane rotation
- ***Slight lateral rounding of the metatarsal shaft - As the 1st metatarsal rotates, we see an increased concavity of the lateral side because this is the plantar concavity coming into view (D’Amico)
- ***Lateral displacement of sesamoids
NOTE: Historically, we thought the 1st metatarsal has drifted medially off of the sesamoids, so we need to cut the bone and put it back over top of the sesamoids – this is NOT the case… Instead, the entire metatarsal-sesamoid complex is rotated into a valgus/pronated position
33
Multi-planar deformity
- So… if a bunion is Multi-Planar, then it requires Multi-Planar Correction
34
Capsulorrhaphy
- Tightening the capsule so sesamoids appear to be under 1st metatarsal head
- Use soft tissue so the sesamoids look to be placed correctly on AP radiograph
- They will then be out of their spots on the 1st metatarsal and sitting right on the medial crista
- They don’t want to be there, so they will shift back
35
Sesamoid correction – Dayton and Okuda studies
- Both found that supination (varus) rotation of the 1st metatarsal (or distal segment of the 1st metatarsal) led to complete reduction of sesamoids WIITHOUT doing a capsulorrhaphy
36
Distal 1st metatarsal procedures
- Create a new deformity in the metatarsal
| - Does not restore anatomical position
37
Deformity correction principles
- WHY IS THIS IMPORTANT???.... THIS IS A DEFORMITY THAT WE ARE SURGICALLY ADDRESSING
38
Anatomic Axis
o Mid diaphysis line (center of bone to center of bone)
39
Mechanical Axis
o Line formed by connecting the center of the distal and proximal joints (center for joint to center of joint)
40
Level of deformity – Deformity correction rules (D. Paley)
- In a bunion, the anatomic and mechanical axes are NOT lined up
- NOTE: Anything we do surgically, should aim to restore the alignment of the anatomic and mechanical axis – We want them to be PARALLEL
41
Restore normal anatomy
- To restore normal anatomy we have to restore axis alignment in three planes
- In a normal first metatarsal the Anatomic Axis and the Mechanical Axis are co-linear
- The metatarsal is usually neutral in coronal rotation
42
CORA – Rule #1
- CORA: CENTER of ROTATION ANGULATION***
- This is important because this is the DEFORMITY and we should be correcting the DEFORMITY
- The CORA is WHERE we need to do our surgery, or we will not be able to get the axes lined up appropriately
- Intersection of the Proximal Anatomic Axis (PAA) and Distal Anatomic Axis (DAA) of the two segments being corrected
- The level of deformity is NOT in the metatarsal – the metatarsal itself is NORMAL
- ******The CORA is at the metatarsal cuneiform joint*****
- Metatarsus Primus Adductus
- ACA(Axis of Correction of Angulation) in the metatarsal will produce a new deformity
43
Angulation Correction Axis – CORA Rule #2
- The only way to make a straight line out of two lines forming an angle less than 180 degrees is by moving the free end of one of the lines around a point on their cross section (ACA)
44
Paley study (2004)
- “The final correction achieved is related to the relationship between the osteotomy level (ACA) chosen by the surgeon, and the CORA inherent in the geometry of the deformity”
- “If these variables are mismatched, secondary deformities are produced”
- If we choose NOT to correct the deformity at the CORA, we end up with a procedure that is NOT anatomically lined up – deformed/bowed metatarsal with a NEW CORA
45
- “Disregard for the osteotomy rules leads to secondary, or residual deformities” Paley
o The original deformity (IMA) is unchanged
o Mechanical/Anatomic axis mismatch
o Are the forces at the distal and proximal joints optimal?
o Will the joints deteriorate secondary to abnormal forces?
46
Post-op analysis NOTES
you should use the same measurement pre-op and post-op so you know you are correcting the deformity (IM angle) but you cannot do this with a head procedure because you destroy the anatomical axis of the bone by bowing it and creating a new deformity
47
Different levels of deformity
- Are these different deformities?
o NO – Despite differences in IMA, all three have the same level of deformity
- All have transverse, sagittal and frontal plane components
o The first metatarsal is deviated – not deformed
- This means we should NOT be treating the same deformity differently
48
***Three things to look for on the AP radiograph*** TEST QUESTION
3 things that indicate a frontal plane deformity:
o Sesamoid position
o Lateral round sign
o Lateral curvature
49
Outcomes of metatarsal osteotomy and capsular balancing outcomes – Distal procedures
Are the long term outcomes of met osteotomy and capsular balancing as good as we think?
o Agrawal, 2015: 29.8% recurrence in children with 21% revision
o Bock, 2015: 30% recurrence after Scarf
o Iyer, 2015: 64.7% had evidence of recurrence at final
o Raikin, 2014: Complications including recurrence following HV surgery have been reported as high as 50%
o Chong, 2014: long term results worse than we expected 25.9% dissatisfaction at 5.2 yrs
o Pentikainen, 2014: 73% radiographic recurrence of HV deformity of 15 degrees or more at long term follow up after distal chevron
o Okuda, 2007: 25% recurrence with lateral round sign
o Coetzee, 2003:25% recurrence after Scarf
***The fact is, Bunion Surgery is unpredictable based on our current Paradigm***
50
PASA
- PASA is part of a traditional thought process – historically it is recognized as a change in where the cartilage of the 1st metatarsal head is located in relation to the metatarsal head itself
- The way we measure that is by finding the affective articular cartilage of the 1st metatarsal head (draw a line through it), find the TAKE NOTES
- Normal: 0-8°
- Both PASA and postoperative sesamoid position leads to recurrence – this means that surgeons saw too much sesamoids, knew it would recur, but thought it was from not enough capsulorrhaphy, but really it’s because they didn’t correct the CORA
51
Why do we see recurrence?
- Traditionally, joint congruency DMAA (PASA) & TSP are strongly implicated
- This isn’t it… it’s from FAILURE TO CORRECT THE DEFORMITY
52
You may be thinking…
- The results from metatarsal osteotomy and capsular balancing are not really that bad
o The complication rate is not really 30-70%
o Correction of the IMA must occur in more than 30-50%
- There are numerous published case series in which good post-operative reduction in IMA and HAV are reported
- How can this argument hold water?
53
Post-op evaluation
- ***There is unacceptable observational bias in the way we measure before and after***
- STUDY: Coughlin
o “Following distal metatarsal osteotomies, the hallux valgus and IM angles are often not substantially changed”
o “The measured correction of the hallux valgus angle and the 1-2 IM angle with both varied approximately 9° with the different measurement techniques on identical radiographs”
54
PASA measurement
- PASA is firmly entrenched in our current algorithmic paradigm
- Least reliable measurement of all commonly used for HAV assessment
o Coughlin, 2001, 2002 and Chi, 2002
- Some consider PASA to be a radiographic ARTIFACT (not actually present)
o The DMAA reduced after the proximal procedure as measured by ALL observers and averaged reduction of 3.9 degrees Chi FAI 2002
- ***If the DMAA/PASA is intrinsic to the bone it should not change following proximal correction procedures***
55
Real or artifact?
- ARTIFACT – PASA is only an artifact – it does not exist
- When you de-rotate the 1st metatarsal in the frontal plane, PASA looks completely normal without doing anything to the metatarsal head
- Result of IMA correction along with de-rotation of the pronated first metatarsal without distal bone or soft tissue procedures (Dayton, Feilmeier, 2013)
o IMA Decreased 9.59 degrees
o HAV Decreased 17.77 degrees
o ***PASA Decreased 18.11 degrees without distal realignment***
o TSP improved by 3.8
56
Effect of coronal plane rotation
- The Effect of Coronal Plane Rotation of the First Metatarsal on Alignment of the First MTPJ
- Metatarsus Primus Adducto Valgus: Mechanics leading to the deformity, allowing progression, and as a part of recurrence
- Common methods of bunion correction do not realign the bones they make a new deformity and leave the joint misaligned
- This correlates with observed reasons for complications
- No matter where we cut the metatarsal we see the same non-anatomic alignment of MTPJ?
- The bump is gone but the original tri-plane deformity is not corrected and the MTPJ is not anatomically aligned
57
Could recurrence be due to flawed philosophy?
- We are taught to individualize treatment and pick from a variety of over 130 procedures based mostly on 2 dimensional radiographic parameters - HAV, IMA, PASA and Sesamoid Alignment
- How can we possibly get the correct answer consistently with this thought process? Variability is the enemy of consistent quality
58
Fundamental deficiency
- FUNDAMENTAL DEFICIENCY: Algorithms for procedure selection are based on 2D radiographic representation of the anatomy
- Transverse plane predominates
o We focus on the IMA, HVA and DMAA
o We make procedure choices based on the degree of the deformity rather than the anatomic level of deformity
o The net result is hundreds of procedure choices and high variability
- Sagittal plane is talked about less
o Elevation and hypermobility
- What about the coronal plane?
o Very little attention has been focused
59
Concepts to consider as causes for less than optimum outcomes
- Disregard for the level of deformity
o Not fixing the original deformity at the CORA
- Failing to restore the anatomy in all three planes
o Focusing solely on the transverse plane of the deformity
- Inaccurate representation of PASA
o This transverse plane measurement may be just an artifact
- Unpredictability of soft tissue balancing as a component of the corrective procedure
o MTPJ capsular balancing for correction of sesamoid and hallux alignment does not offset the lack of alignment produced by the osteotomy and deteriorates in time
60
QUESTIONS
- What plane does the hallux primarily move in in a “normal foot”? Sagittal
- What anatomic structures are a part of this? Extensors and flexors
- What happens if the hallux rotates into a valgus position in the frontal plane? Both sagittal and transverse motion is present
- What movement occurs now to the hallux now? Lateral deviation
- What impact might this have on the first metatarsal? Retrograde buckling, moving metatarsal more medial, causing even more transverse plane motion (moving the metatarsal even more medial), lose sagittal plane motion
- If we do a transverse osteotomy (i.e. Austin), overtime same deformity can cause pathology
61
Paley: Disregard for normal anatomy
- “Disregard for the deformity rules leads to secondary, or residual deformities” Paley
- Original deformity remains, new deformity is created – Mechanical/Anatomic axis mismatch
- The forces acting at the distal and proximal joints are abnormal
- Will the joints deviate or deteriorate secondary to abnormal forces?
62
Restore normal anatomy
- To restore normal anatomy we have to restore axis alignment in three planes
- In a normal first metatarsal the Anatomic Axis and the Mechanical Axis are co-linear
- The metatarsal is usually neutral in coronal rotation
63
Anatomical analysis
- IF The MTPJ alignment seen on the AP X-ray is a result of metatarsal pronation
- AND the sesamoid to metatarsal groove relationship remains relatively aligned
- THEN metatarsal Rotation, NOT soft tissue balancing is needed, and transverse plane osteotomy cannot correct the deformity
64
Sesamoid position post-op over 14 years
- Transverse and coronal plane position was not corrected
- Retained forces on the soft tissue repair resulted in drift
- Sesamoids are located normally medial & lateral to the crista
65
Hypermobility
- Hypermobility of the first ray does not occur at the TMTJ, if present at all it occurs at proximal joints (Yes, INSTABILITY is present due to mechanics)
- ***Hypermobility as an indication for Lapidus Procedure is a fallacy born of a novel idea from Morton and confirmed by generations of multiple choice test questions and re-publication without confirmation***
- Quoting hypermobility as an indication for TMTJ corrective fusion confirms our lack of understanding of deformity correction principles
66
Lapidus
- It’s not just about doing a Lapidus, because you can do a Lapidus and just address the transverse plane – Correction at the CORA BUT failure to correct rotation leaves original deformity uncorrected
- NEED to have a TRI-PLANE TMTJ arthrodesis procedure if you want to truly correct the deformity
67
Radiographic anatomy – TRADITIONAL approach
- HAA
- Joint congruency
- IMA 1-2
- PASA (DMAA), DASA
- TSP (1st Metatarsal has “moved off” of the sesamoids and fibular is sucked into the interspace)
68
Algorithms for HAV Procedure Selection
- IM severity ( 15 degrees, “Grading”)
- HAA severity
- Metatarsal protrusion distance
- “Hypermobility” at TMTJ
- Congruency of joint (PASA (DMAA), DASA)
69
Bunionectomy alternatives
- There are many ways to cut and reposition bone
- Soft tissue correction
- Exostectomy
- Arthroplasty with or without implant
- Proximal phalanx osteotomy
- Head osteotomy
- Metaphyseal or diaphyseal osteotomy
- Basilar (CBWO, OBWO, Cresentic, proximal chevron, Loison/Balacescu)
- 1st tarso metatarsal joint fusion
- Others (Cuneiform osteotomy, Epiphysiodesis, Joint Replacement)
70
***Traditional algorithm in a nutshell***
- Small IMA = Soft tissue or distal (metaphyseal) osteotomy
- Moderate IMA = Metaphyseal or diaphyseal, with or without soft tissue correction
- Large IMA = Diaphyseal or base, possibly with head osteotomy also, with or without soft tissue correction
- PASA = Reverdin or “rotational” (in transverse plane) osteotomy
- DASA = Proximal Akin (for a proximal deformity)
- HIA = Distal Akin (for a distal deformity)
71
How to answer her questions:
- I have to ask you questions on the historical points here
- First thing – look at the radiographic findings, cross off anything normal, then look at abnormal
- Then look at list of procedures and see what procedure can correct the abnormal value
- Example: Patient has a high IM angle and a high PASA – if one of the options would correct the high IM angle but not the PASA, cross it off. Continue to work through the list of possibilities systematically.
If you know what procedures are done in what part of the bone, you will do perfectly fine ***
