9 - Lisfranc's Injury Flashcards
Key learning points
- Define the key tarsal-metatarsal joint anatomic landmarks used to assess injury
- Describe the radiographic features of TMTJ injury
- Compare the evidence based treatment recommendations and the evolution of treatment recommendations
Anatomy
- Lis franc’s joint (3 Cuneiforms, Cuboid, Bases of metatarsals 1-5)
- Intrinsic Osseous Stability is provided by the Roman arch of the metatarsals and the recessed keystone of the second metatarsal base
- Further stability is provided by ligaments
Ligament anatomy
- Inter-osseous ligaments connect metatarsals 2 - 5 at the bases (Both dorsal and plantar)
- No transverse metatarsal ligament from the first to the second
- Plantar ligaments are stronger and larger
Lis franc’s ligament
- Strong oblique ligament from the plantar aspect of the medial cuneiform to the base of the second metatarsal
Associated structures
- Dorsalis pedis artery courses between 1st and 2nd metatarsal bases
- Deep peroneal nerve runs alongside the artery
Lis franc’s injury
- Fracture and dislocation of the tarso-metatarsal joint complex
- May be a pure dislocation due to ligament rupture only (Primarily Ligamentous)
- May involve fractures of the metatarsals and the cuneiforms (Intra articular and/or Extra articular)
- Lots of variability
Classifications of lis franc’s injuries
- Quenu and Kuss (1909) – Homolateral, Isolated, and Divergent
- Modified by Hardcastle in 1982
- Further modified by Myerson in 1986
- Fail to encompass all injury patterns especially crush injuries and do not establish prognosis
Reality of classifications
o Lots of them
o Do they really help? No
What MUST you evaluate in a Lis Franc’s injury?
o Angulation & Translocation
o Transverse & Sagittal displacement
What may hide a true deformity?
Spontaneous reduction
o **Does it match the other side?
o **Careful attention to the “key-stone”
Subtle Lis Franc’s deformity
The subtle ones are the toughest
- Often missed in the ED
- History and physical exam is key
- Alignment of the second metatarsal base medially is an important radiographic finding
Mechanism of injury
- Trauma
o Motor vehicle accidents account for one third to two thirds of all cases
o Incidence of lower extremity foot trauma has increased with the use of air bags - Direct or Crush injuries
- Sports-related injuries are also occurring with increasing frequency
Mechanism of injury - indirect force
- More common than direct
- Result from axial loading or twisting
- Metatarsal bases dislocate dorsally more often than plantar
Advanced imaging
- CT and MRI are unlikely to be helpful with either diagnosis or treatment
- Must be suspicious due to the possibility of spontaneous reduction
- Stability is key Do a Stress test***
- Comparison to the other foot
Clinical questions for treatment of TMTJ dislocation
- Reduction vs. No Reduction?
- Closed Reduction with Pin vs. Open Reduction?
- Wires vs. Screws?
- ORIF vs. Fusion?
Example
- Positional changes from unstable Lis franc’s causes severe progressive functional abnormalities
- Angular and Translational
Notes on x-ray
o “Skinny” joint on the lateral view – no normal joint space
o Sign of degenerative joint disease
o Subchondral sclerosis
o This is a sign of DJD
o 2nd metatarsal is set back behind joint of 1st metatarsal
o 1st metatarsal should be parallel to talar neck line on the lateral view (“Meary’s line”)
** KEY POINTS **
- TMTJ stability and alignment is important for function
- Arthrodesis is the most stable option for repair with the lowest revision rate
- There is no good argument from a surgical or functional standpoint for “Joint Preservation” in the TMTJ
- Locking plates provide a stable, load bearing construct that tolerates external stresses better than traditional AO techniques
- Must prioritize deformity correction in both acute and late reconstructions
Case study - alignment on x-ray
- Base of second metatarsal is not lined up with the intermediate cuneiform
- This is how you know that there is a dislocation
- On an AP x-ray this is the most reliable clue to why there is an injury and this is not just normal anatomy
Case study - fracture
- Fracture of base of 2nd metatarsal
- Evulsion of Lis Franc’s ligament which goes from base of 2nd metatarsal to medial cuneiform
- All the cortices of the joint line up,
- If you have the evulsion, you have a severe instability and it needs to be addressed
Case study - dislocation, no fracture
- Base of the 1st metatarsal and medial cuneiform
- No fracture, so this is a purely ligamentous
- Much worse than a fracture
- Worse prognosis
Classifications
Classifications = not important, not clinically relevant
Case study - 3rd metatarsal fracture
- Base of the 3rd metatarsal is fractured
- Do a contralateral x-ray to be able to compare
- To get a lateral film will tell you if there is any sagittal plane deviation
- Stress test shows you that there is a severe injury
- Substantial dislocation is present
- Advanced imaging is not necessary
- The key to a Lis Franc’s injury is restoring stability – do not worry about restoring “function”
- CT and MRI are unlikely to be helpful with either diagnosis or treatment
- Must be suspicious due to the possibility of spontaneous reduction
Instability
- Do you need to reduce it?
- Open or closed? Closed reduction should always be tried first according to literature
- Joint NEEDs to be stabilized, one way or another
Elevated first ray
- 1st ray elevation leads to forefoot supination, leading to compensation via hind foot pronation
- Hallux limitus will occur
- Additional stress on the lateral metatarsal heads
- Reduces weight bearing on the medial foot
- Hind foot pronation leads to medial rotation of the knee
- Midfoot abduction leads to a rotational equilibrium leading to pronation of the foot
Small shift equals big deformity
- Even when it is just a “little bit off” it is a big problem because it will get worse 100% of the time
Reduction vs no reduction
- Instability is well known to result in progressive collapse biomechanical dysfunction and painful arthrosis
- All studies that compare accurate reduction to mal position show better outcome for accurate reduction
Percutaneous fixation
- Instability remains
- Imperfect reduction – there’s no way to get it perfect
- Intraarticular fractures need to be perfect
- Studies do not support the use of percutaneous fixation
- Highly variable
- Inadequate reduction leads to continued instability and further damage
- Almost everyone recommends ORIF
- 100% of patients had DJD of TMTJ regardless soft reduction
Screws or pins
- Incomplete stability after ORIF
- Loss of reduction after pin removal
- High incidence of DJD
- High rate of revision surgery
- ORIF needs revision because they will fail, even with the best options we have
- 3 operations is not uncommon
Arthrodesis vs ORIF
- Even though the evidence is compelling that you need stability and arthrodesis, some still say you need to try ORIF first
- Arthrodesis has much better results
ORIF stats
- 15 of 20 had loss of correction, arthrosis and or pain
- 16 out of 220 needed hardware removal and secondary surgery
Ligamentous injury ****
ORIF
o Dorsal instability
o Medial second metatarsal base fracture
o Much more stable
o This is because the dorsal ligaments are the only ones that are torn, but they don ‘t even matter
o Plantar ligaments are still intact and they are strong
Arthrodesis
o Plantar instability
o Pure ligamentous instability with dislocation
o Less reliable
Fracture
o Better outcome than if it is purely ligamentous
ORIF - Henning 2009
Prospective randomized study of patients presenting with Lis franc’s fracture dislocation
o ORIF vs primary arthrodesis of 1-2-3
o Follow up for 1 year
o 94% fusion rate in the arthrodesis group
o ***Found similar short term stability …
ORIF vs complete TMTJ - Muiler 2002
- ORIF did better functionally than complete TMTJ arthrodesis 1-4
- Only fuse 1-2-3
Late or revision arthrodesis - Rammelt 2008
- We can always fuse it later, but no one actually wants 2-3 operations
- We can talk people into it, but we should not be doing this
- Primary arthrodesis had better functional results, less complicated recovery than secondary arth
- Medial column fusion gave better result than fusion of all 5 joints
- It is a much harder operation
ORIF
- 2nd and 3rd surgeries common
- High DJD in first 5 years
- No post op advantage
Case study
- Evulsion fracture off of the medial cuneiform (or 2nd metatarsal), but looks more like medial cuneiform
- Lateral deviation of base of 2nd metatarsal (possibly – very subtle)
- Implication of the evulsion fracture is that it is an intraarticular and involves
- Lis Franc’s is more plantar than dorsal, so it is the most important
- If it is truly unstable with a stress test, arthrodesis of 1-2-3 is the best treatment option
- Alignment is key for arthrodesis
- Align the 2nd with intermediate cuneiform and
Case study
- Joint space is diminished 2-5, joint space is irregular in 1
- Treatment is arthrodesis
SUMMARY
- Closed pinning and ORIF – high failure rates and high revision rates
- Consider adjacent joint degeneration
Alignment
- 1st ray is elevated
- Leads to hallux limitus
- It causes degenerative changes of the first MPJ with arthritic changes
Surgical technique
- 2 incisions
- Only make incision over 4 and 5
- Fuse 1-2-3
- Lateral incision is much more lateral than you would think
- Need to know the anatomy “associated anatomy slide on DP
- Not fusing 4 and 5, just debriding it
Diagnosis
- Hard to diagnose
- Just as bad as leaving it, is fusing it in an abnormal position
- The key is that they come in and they are subtle, they don’t do a stress test
- Stress test – thumb pressure on cuboid, hand pressure on 1st metatarsal
Review
- Type II= slip of the physis and fracture of the shaft
- Non-articular and has robust
- Relax the patient and reduce it closed
Steps for reduction of fracture
- Anesthesia
- Increase deformity
- Traction
- Reduce deformity
- Maintain reduction (screws, immobilization, cast, etc.)
