1st MTP Joint Dissection: Surgical Anatomy

• Anatomic dissection of the 1st MTPJ is used for surgical anatomy of the foot

Hemostasis

• Allows surgeons to better visualize and identify tissue planes
• Minimizes operation time
• Reduces post-operative complications
• Technique involves a vasoconstrictor such as epinephrine (1:200,000)

Anatomic Dissection

• Involves identification of tissue planes and atraumatic technique
• Principles include controlling bleeding, creating full surgical exposure, and ensuring clean separation of fascia
• Clean separation of superficial fascia from deep fascia contributes to improved post-operative healing due to decreased edema, pain and scarring
• Major components are controlled depth incision placement, tissue plane dissection, and preservation of blood and nerve supply
• A fundamental step is the dissection of subcutaneous tissues due to superficial arteries, veins, nerves, and lymphatics' primary network
• Manipulation of the subcutaneous layer is key in anatomic dissection

Techniques for Dissection

• Sharp dissection is suited for thin tissue
• Requires appropriate retraction of skin edges, placing fibrillar elements under tension
• Blunt dissection is for thick tissue
• Uses a spreading motion with a hinged instrument such as Metzenbaum scissors

Reflection

• Reflection involves lifting, folding back, or retracting a layer of tissue
• For medial subcutaneous reflection, start medially at the base of the proximal phalanx
• Be careful not to lacerate the medial plantar neurovascular structures
• For lateral subcutaneous reflection a deep pocket is created along the lateral aspect of the proximal phalanx via finger dissection
• A Weitlaner retractor is used when performing lateral SQ reflection for interspace releases

Hallux Valgus Surgery

• Includes anatomical dissection of tissue plane, plantar lateral release (1st MPJ), arthrotomy/capsular & periosteal reflection, exostectomy (bunionectomy), muscle-tendon balance (adductor tendon transfer) and post-op rehabilitation

Incision procedure

• Uses dorsomedial incision that follows the primary deformity
• A universal incisional approach begins proximally about the midshaft level of the MT head
• Ends proximal to the hallux interphalangeal joint, medial to the EHL tendon

First Interspace Dissection

• Inadequate release of contracture can lead to recurrence
• Evaluate joint motion before and after release in a controlled sequence
• Involves sequential release of a plantar lateral contracture
• Release the adductor hallucis tendon, and avoid cutting the lateral collateral ligament, because this can result in hallux varus
• Release the fibular sesamoidal suspensory ligament
• Cut the lateral head of the FHB or excise the fibular sesamoid
• This may result in patient imbalance

Capsulotomy

• A capsulotomy makes an incision in a capsule
• Medial capsulotomy should follow the release of lateral contractures to correct a hallux valgus deformity
• Characterized by capsular and periosteal reflection
• The primary consideration is that the periosteal tissues provide blood supply to the MT head and neck
• Do not take off all periosteum off of the bone because it can result in avascular necrosis
• Linear longitudinal incision from MT neck to proximal phalanx base along the dorsomedial aspect of the MPJ
• Ensure to keep the synovial fold intact, because this provides blood supply to the MT head

Medial Eminence Resection

• Creates a flat surface to perform an osteotomy
• It is important to only minimally resect the eminence
• You have to make sure to preserve both the sesamoidal groove and sagittal groove
• Loss of these grooves can result in instability and subsequent hallux varus

Muscle Tendon Balancing

• Involves release of lateral contracture, correction of osseous deformity, reestablishment of normal balance, and adductor tendon transfer
• Used to maintain derotation of capsular tissues around the MT head, and enhance medial capsular integrity
• Medial capsulorrhaphy is tightening the joint capsule
• This is the final step to reestablishing balance around the 1st MPJ
• This procedure removes redundant capsules and tissue that have been attenuated

Osteotomy Principles

• The axis guide principle involves the surgeon following resection of the medial eminence
• The surgeon then inserts a 0.45-inch K-wire medial to lateral to arrange it and accomplish Dorsiflexion, plantarflexion, shortening, lengthening, or maintenance of length
• To maintain the length of the 1st MT, set the axis guide perpendicular to the 2nd MT
• Along w/ plantarflexion, it is perpendicular to the 2nd MT, and going from medial-dorsal to plantar-lateral
• "If a patient comes in with hallux limitus due to a long 1st MT osteotomy, make the axis guide proximal-plantar
• To lengthen the 1st MT, go proximal-medial to distal-lateral in reference to the 2nd MT
• maintain: MD to PL
• lengthening: PM to DL
• shortening: DM to PL
• To shorten the length of the 1st MT, go distal-medial to proximal-lateral in reference to the 2nd MT

Surgical Treatments

• Surgical treatment for hypermobile toe involves fusion/arthrodesis/Lapidus
• A statement on "positive dynamic hicks test" instead of saying hypermobile,
• Surgical treatment for “crepitation” in the 1st MPJ is Arthrodesis
• If “crepitation on physical exam” do NOT pick osteotomy and fuse the degenerated joint

Osteotomy

• If the osteotomy depends on intermetatarsal angles, mild (12°) uses Distal osteotomy
• If the osteotomy depends on intermetatarsal angles, moderate (15°) uses Shaft osteotomy
• If the osteotomy depends on intermetatarsal angles, severe (18°) uses Proximal osteotomy/Lapidus
• Normal 1st-2nd IMA is ≤ 9°

Pre-Op Evaluation of Bunion

• Etiologies include biomechanical dysfunction, inflammatory disorders, neuromuscular disorders, trauma, laxity syndromes, congenital malformations, and Surgical complications
• 1st MPJ kinematics (axis of motion) acts on both transverse and vertical axes
• Vertical which performs transverse motion but is insignificant
• Transverse performs sagittal motion which includes Flexion and extension
• The transverse plane is the area in which most motion occurs at this joint and you want 65° of DF and 15° of PF
• ROM includes neutral which is 20-30° of DF from neutral, propulsion, wich is 10-15° of DF
• The Met will glide posteriorly on the sesamoidal apparatus

Biomechanical Dysfunction

• May involve the patient's heel everting w/ a flatfoot, if the heel is everted w/ a flatfoot, you're unable to lock the midtarsal joint because the STJ is pronating instead of supinating
• The PL tendon is no longer functioning correctly and this results in DF of the 1st ray instead of PF, resulting in hypermobility
• This causes an increase in intermetatarsal angle due to changes in vector force of the EHL & FHL
• The abductor hallucis will migrate plantarly, resulting in pronation of the hallux
• The adductor hallucis contracts, resulting in metatarsal-sesamoidal subluxation
• Involves change in the axis of motion of the first MTPJ, involves eversion of the metatarsal which is a three dimensional deformity
• During bunion development there will be eversion of the 1st MT

History and Physical Exam

• Typical patient history involves a superficial painful bump, deep joint pain, radiating neuritic pain, pain at the end of ROM, pain that relates to sesamoids
• If there is deep joint pain, consider MPJ fusion
• Suspect degenerative joint disease and that the Patient has pain in and out of their shoes
• Radiating neuritic pain may arise from nerve excision or patient may have a Joplin's neuroma of the medial dorsal cutaneous nerve
• Pain at the end of ROM can stem from remodeling of the MT head and a dorsal flag sign indicating a cheilectomy
• Typically associated with hallux limitus deformity
• Pain relating to the sesamoids may indicate fusion, the patient likely has an arthritic MPJ
• suspect degenerative joint disease an osteotomy would not fix anything

Physical Exam and Angles

• Physical Exam involves the Klaue device, Root technique and Dynamic hicks test and Questions to ask regarding the 1st ray
• Klaue device (+) indicates hypermobility
• Root technique, normal is 5mm up and 5mm down, anything greater is hypermobile and you perform a Lapidus
• When using the dynamic hicks test, move the 1st ray while the windlass mechanism is engaged
• Positive dynamic hicks test indicates hypermobility and it is addressed with Lapidus
• Considerations include, transverse plane instability, recurrent IM angle deformity, need for a soft tissue release and if you should osteotomy or fusion
• Is there still valgus roation of the toe
• Proximal articular set angle (PASA) normal is 0 - 7.5°
• Used to detect if there is articular/cartilage deviation
• PASA is treated with reverdin surgeries which is a wedge procedure These procedures take a wedge out of the bone to realign deviated cartilage

Angles

• There is the distal articular set angle that is measured at the phalanx at the bed space
• Measures structural malalignment at the base of the proximal phalanx
• Distal articular set angle normal is 0 - 7.5°
• If a patient has a high Distal articular set angle, you perform osteotomy closer to the base of the phalanx
• Distal articular set angle is Not very common, only seen in patients with arthritis
• The Hallux abductus angle is Measured using AP X-ray
• Measures abduction of the proximal phalanx in relation to the 1st MT
• Measurements include Normals 0 - 15° Hallux abductus angle (HAA) buzzword: tracking joint
• There is the Meary's angle which tells you the relationship of the bisection of the 1st MT to the bisection of the head & neck of the talus
• They should be aligned or parallel
• CT "alpha angle" measures alpha angle views Coronal view
• This angle is formed by the line that connects the crista & the dorsal center of the 1st met
• The line vertical to the ground is defined as & is used to measure the 1st met pronation
• Used mostly to tell how much the 1st met is rotating
• Intermetatarsal angle (IM angle) Normal is 10° (2)
• It Includes: rectus foot and adductus foot

Reverdin - Bunion and Angle Concepts

• Metatarsus adductus angle (MAA) measures if there is Anyt greater than 15° is abnormal
• Distal cut is parallel to the articular cartilage in the Reverdin procedure
• The proximal cut is perpendicular to MT in the Reverdin procedure, this is to correct the high PASA 1- The blade can damage the superior surface of the sesamoids resulting in traumatic sesamoiditis 2- The blade can damage the superior surface of the sesamoids resulting in arthritis between two areas
• Reverdin green is a one version of a reverdin osteotomy and Protects the sesamoids via plantar cut

More Osteotomy

• Reverdin laird: Reduces the IM angle along w/ fixing PASA
• it Introduced fracture of the lateral cortex to transpose & reduce the IM angle
• May Shortens the MT & can result in transfer metatarsalgia
• If A 55 y.o with IM 14° , PASA os 17° and a track-bound joint then do a reverdin laird procedure
• The Tood modification Alters the axis of the plantarflexion is technically difficult
• Tilted down to address elevation
• Look for : Unrectricted is associated with no soft tissue or cartilage deviation -Look for Tracking ha- there’s a hallux abductus
• A trAck bound the PASA

Rotation

• What you do for Valgus rotation, occurs, -can be lateralized semomoid -1st insufficiency or loading of the PL anyetiolgoies results in the eversion of the the metarsal
• This results in hypermobility Buzz word HYPERMOBILITY- TX is lateral release fusing 1st Mt metatarsal a. pt . weight - bearing taking ap+ axial b. Pt DF assess where the sesamoids sit over crista c. M< rotation you notice M-C lateral head shape d. Hailux interpangulus – abnormal in the Ditasl aspect structural proximal phalanx length more than lateral caused medial length - Nromral is 10 degrooe
• Clinical abduction , on weight bearing: EHL tendinitis
• x Ray : Im amgle relative length. AP

Additional Considerations: Radiographic View

Hall ark radio sign al lateral X-ray -bunion deformity

• See amt of dorsal displacement and its M-C1st lift - mm dorsal in. mm dorsal Txlapuidas Hypermoblity Ray – plantar gapping Cuniform Joint: shouldnt be space
• This shows the first MT is rotating in a hypermobile for TX LATERAl RELASE. So toe derotates

Mechanical and Anatomic Issues

Mechanical axis : Straight Joint. Asses medial and lateral : axis deformity Plannin

• method angular to fuse
• Talar as Joint for medial Axis Is. Complicating in :

Anamotnic

Mid diepheal Measuring Im Angle - use Axis If 1 mt to 2 Nd mt axis

• Conter rotating (Cora)1ST joint IS CORN
• Apex ( of the midformity
• osteotomy Side the apex WILL prooduce a secondary translation the Cora- Metatarsal protrusion distal normal +l- 2

MT width

• Normal . width to .00 on AP Tibia semiomid position: is NORMAL to position 4 7 HAV sevde defmroity: Look at Joint conditions
• Draw Lines + Angles - If outside the Angle, there is Derailed
• Subluzated Is In Side Angle
• 1mt Head. Shape : 0. If Soften ( soft tusse Ex) high Hallucabius and Ex is normal angle which we kno is associated
• with Soft Tusse Definity. I
• Structural - pasada-Dasta # hall Pasada- Dasta- Ha combined

Procedure Considerations

• HAV (hallux abducro angle) increased 1 -Mangle and is HVA – A: evident on X-Rays no 1 m Pronation status is M< 10 evidence of degenerative joint disease T< Met Oustemom
• increased Mangie Huva w b: avidnet on XRAY pronatio with a no dubeatnon, 2b M Joint. with that 1
• Treated with Triplane correction + consrvwtive , and that includes 1 Met
• Class 3 , 1M, Hav 11 and 1 - metatarsure adductions , NO DEGEN joint Tx; Lapidus with transeverse Corectoon 30061 Met - Tarus
• ⁴. HAS IM angie HVA with out 1 st Pronation : and a Status - M-A with end of djd Tx 15 Mti arthrodesis

What procedures have you heard about

-Akina

  A. Opertoon - that correct the structural deformaty Of promao Proximal Phalanz  (Hl). NOT A PRIMARY
    TX for Hallous . TX . ONLY ADJUT - Akin - does not TX HALLux abductoangle (HAA)
  4.  Is No High Haa ange: . If pt   has It Dist al.  If 1 )asa - then DO Proximal

Procedure : 1, soft 713 : Remove a dueto tendon 2. Remove firula seionod- High H-angle- The

• A: Medial Ousing wede of proxinno : Remove weige - result is - to straight and redution OF IM Angle . dista Atkin - a Closing Wedye : to most common to and .

Mores Procedural Options

4, Oblique - so you con a compression , in bone 5- Clindriocal - .T> B to txt An 1> elongated proximals b. to txt abnoramally elgonated phalanz complication BICA plolangix - long. We break the binge therefore stablity. Cylridia

Proxmial and Sagittal

2 shortens - no hi- or Dasa - And shotens Hallius

1. Proximal : To fix increated Dasa. And ◦Dasa tx - the offset V with proximals tx is. the MS 8 is 16 Im hA , DaSa IS 16. H1 Is , tx is offset Proximal atin = high DASA

• Tx - the Hallux Lmmus
  • Decompress MPU On proximal P
• Side and to txt Halloimus: Regwald Procedi

What Procedures Do For The Hallux Valgus

• A: the General M< angle Below 150 - distal 71x15 - the Common and and tx buninectomy Elevated Im is hovizontol V C cut for all of 69 69 tx NO DOO IN at 15 or. Abnormal angle - UP TO 15 to d neck and 0-7 is normal Pasa / normal protruston / has Comgrous or Denmed
• If Relalove reducon is on Met, they can do more combined with other . If non Com - than the proedure of that , there is plane de for mity to satital grooved a MT

Anatomic dissection of the 1st MTPJ is used for surgical anatomy of the foot. Hemostasis allows surgeons to better visualize and identify tissue planes, minimizing operation time and reducing post-operative complications. Anatomic dissection involves identification of tissue planes and atraumatic technique.