54: Hallux Limitus/Rigidus - Bennett

Question 1

define hallux limitus

Answer 1

Deformity of the 1st MPJ in which base of proximal phalanx of hallux is subluxed plantarly upon the 1st metatarsal head

Hallux cannot dorsiflex 65° during propulsive phase of gait and this limitation of motion is called hallux limitus

Question 2

what is hallux rigidus

Answer 2

When all motion ceases, it is called hallux rigidus

Some consider hallux limitus to be the pathology that leads to the deformity of hallux rigidus

Question 3

s/s hallux limitus/rigidus

Answer 3

• Marked by patient’s complaint of pain
• Grinding and limited motion at the 1st MTPJ
• Dorsal bump on the 1st metatarsal head
• Combined with radiographic findings

Question 4

DJD and hallux limitus

Answer 4

• Osseous compression occurs on dorsal aspect of 1st MPJ
• Dorsal aspect of proximal phalanx jams into upper 1/3 of articular surface of metatarsal head which results in DJD

Question 5

etiologies of hallux limitus

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Answer 5

1. hypermobility
   
   1. Hypermobility of 1st ray, in association with eversion of the foot caused by abnormal STJ pronation in a rectus foot type. Hypermobility caused by inadequate plantar stabilization by peroneus longus. Hypermobility with eversion needed so that medial force will dorsiflex 1st metatarsal
2. foot type with increased medial forefoot force
   
   1. everted calcaneus, evereted FF wtih plantarflexed 1st ray or flexible FF valgus (load 1st ray sooner with greater force)
3. Immobilization of the 1st ray
   
   1. Arthritis at the 1st metatarsal-cuneiform joint. Acquired in long standing cases of abnormal STJ pronation due to subluxation at 1st met-cuneiform joint
   2. Calcaneal-navicular synostosis
4. Excessively long 1st metatarsal
   
   1. Weight-bearing forces during propulsion concentrated for excessive period at distal 1st metahead which prevents plantarflexion of 1st ray and leads to delay in proximal migration of transverse joint axis to allow dorsal migration of phalanx on the 1st metahead.
5. Metatarsus primus elevatus
   
   1. Congenital-1st ray has full range of motion, but lacks adequate plantarlexion to allow normal hallux dorsiflexion
   2. Acquired-less than normal 1st ray motion, and 1st ray fixed in elevated position
6. High Heels
   
   1. Increasing heel height reduces 1st MPJ dorsiflexion.
   2. 1” heel automatically dorsiflexes 1st MPJ by 20°; each additional inch further reduces it another 14°. If we need 65° for normal function, a 2” heel allows only 31° of dorsiflexion (or the joint needs to dorsiflex around 100°)
7. Trauma
   
   1. Blunt trauma or turf toe

Question 6

what is necessary for normal 1st MPJ motion?

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Answer 6

• 1st. Ray plantarflexion
• 2nd. Metatarsal longer than the 1st. (normal parabola)
• Normal intrinsic and extrinsic muscle function
• Normal sesamoid function
• Intact base of the proximal phalanx

Question 7

describe the function of the 1st MPJ in gait

Answer 7

midstance to toe-off

• hinge motion for first 20 degrees
• arthrodial motion
  
  • Sliding motion with plantarflexion of 1st ray with heel lift, STJ supination, and normal sesamoid function.
  • Dorsiflexion to end ROM during propulsion with 35 ° knee flexion and 20 ° ankle plantarflexion

Question 8

design of head of met

Answer 8

cam shape

rolling, sliding, and compression can occur

Question 9

amount of dorsiflexion needed for gait

Answer 9

65-75 degrees

Question 10

as the 1st ray plantarflexes it ….

Answer 10

slides proximally

Question 11

what is happening in propulsive phase of gait?

Answer 11

hip extension

knee flexion

ankle plantarflexion

Question 12

Restricted 1st ray plantarflexion prevents proximal gliding of metatarsal over sesamoids and …

Answer 12

subsequent positioning of the 1st metatarsal below the transverse plane of the lesser metatarsal heads

Question 13

describe the windlass mechanism

Answer 13

• Heel lift w/ankle plantarflexion will dorsiflex the mpj.
• Tightening of the plantar fascia, to raise the arch and shorten the foot.
• Raising the arch will resist elongation of the foot, and assist in resupinating the subtalar joint.
• Windlass function is blocked by any force that drives the 1st ray up (1st ray is prevented from plantarflexing, hallux can’t dorsiflex, plantar fascia tension increases, and 1st MPJ compression increases)

Question 14

key radiographic findings for hallux limitus

Answer 14

• Functional adaptation of bone
• Occurs in young patients by resorption of dorsal bone at 1st metahead and allows increased range of hallux dorsiflexion
• In adults, this same intermittent compression leads to osseous proliferation on the dorsal surface of the 1st metahead and produces a spur or “dorsal flag” sign
• Degenerative changes at 1st MPJ
  
  • Subchondral sclerosis, asymmetrical joint narrowing, subchondral cysts, and osteophytes will develop with broadening of the base of the proximal phalanx, and metatarsal head.

Question 15

sequelae of hallux limitus

Answer 15

• 1st MTPJ Pain, limited motion
• IPJ arthritis
• Nail trauma
• Shoe pressure on dorsal bump leading to pain or cystic changes in EHL or adventitious bursa over bone
• Lesser metatarsalgia

Question 16

oloff and jacobs radiographic hallux limitus classification

Answer 16

• Grade 1 (minimal adaptive changes)
  
  • metatarsus primus elevatus (noted)
  • plantar subluxation of phalanx on metahead
  • rearfoot pronation
  • pain on end r.o.m.
• Grade 2
  
  • flattening of 1st metahead, with possible osteochondral defect
  • small dorsal exostosis
  • pain on end r.o.m.
  • passive r.o.m. limited with forefoot loading
• Grade 3
  
  • more severe flattening of 1st metahead
  • osteophytes, especially dorsally on both metahead and phalanx
  • assymetrical joint narrowing
  • subchondral eburnation with possible cysts
  • pain on full r.o.m. with crepitus
  • degeneration of articular cartilage
  • broadening of 1st MPJ
• Grade 4
  
  • total obliteration of joint space
  • loose bodies
  • less than 10 degrees total motion
  • worsening of grade 3 changes

Question 17

functional vs. structural hallux limitus

Answer 17

• Structural =hallux dorsiflexion decreased when first ray is loaded (passive dorsiflexion of great toe in RCSP) and unloaded (passive dorsiflexion of great toe in NCSP)
• Functional = hallux dorsiflexion decreased only when the first ray is loaded
• Structural = limited dorsiflexion loaded and unloaded
• Functional hallux limitus may develop into structural
• Functional does not have the arthritic changes restricting hallux dorsiflexion
• Functional is due to hypermobile dorsally displaced 1st ray that possibly can be controlled with orthotics that prevent abnormal pronation and allow for 1st ray plantarflexion

Question 18

how do you check functional vs. structural hallux limitus?

Answer 18

• patient sitting
• with functional hallux limitus you will have decreased motion when dorsiflexion attempted with STJ not in neutral position
• vs. normal movement when STJ in neutral

Question 19

orthotic casting for functional hallux limitus

Answer 19

• Cast with STJ neutral, MTJ fully pronated or locked, and 1st ray plantarflexed (or great toe dorsiflexed)
  
  • To plantarflex 1st ray, push down over 1st met-cuneiform joint
  • If you don’t plantarflex the 1st ray, you will capture excess varus in the cast and orthotic which will lead to 1st ray dorsiflexion
• The end result of this casting technique is to try and increase the rom of the 1st MPJ
  
  • Done with a reverse Morton’s extension, for early stage I
  • However, some people will have less pain with less motion, so use a Morton’s extension to limit 1st MPJ motion by preventing proximal phalanx dorsiflexion (usually achieved by using thin carbon filler instead of orthotic)
  • Deeper heel cup to prevent eversion
  • Kirby Medial Heel Skive: increase supinatory torque

Question 20

reverse morton’s extension

Answer 20

works for hypermobility or elongated 1st met etiologies