Understanding Midfoot Injuries: Anatomy, Mechanisms, Treatment

1. Midfoot Fractures and Dislocations • Anna N. Miller, MD, and Bruce Sangeorzan, MD • University of Washington • Harborview Medical CenterRevised October 2011 • Based on the work of Drs. A. Walling and C. Jones

2. Contents • Lisfranc Joint Injury • Diagnosis • Treatment • Outcomes • Midfoot Crush • Navicular Injury • Cuboid Injury • Cuneiform Injury • Midfoot Anatomy • Mechanisms of Injury • Foot Function and Shape • Treatment Principles • Midfoot Crush • External Fixation • Internal Fixation • Forefoot Crush

3. Midfoot Anatomy • Four Major Units • 1. 1st Metatarsal (MT) <> Medial Cuneiform: 6° of mobility • 2. 2nd MT <> Middle Cuneiform: Firmly Fixed • 3. 3rd MT <> Lateral Cuneiform: Firmly Fixed • 4. 4th – 5th MT <> Cuboid: Mobile 1 2 3 4

4. Midfoot Anatomy • Osseous stability is provided by the “Roman arch” of the metatarsals and the recessed keystone of the second metatarsal base 1 5

5. Midfoot Anatomy * • Associated Structures • Dorsalis pedis artery*: between 1st and 2nd MT bases • Deep peroneal nerve: runs alongside the artery

6. Midfoot Anatomy • “Column” Anatomy • Medial column includes talonavicular joint, cuneiforms, and medial three rays of the forefoot. • Lateral column includes calcaneocuboid joint and fourth and fifth metatarsals.

7. Midfoot Anatomy • Medial column joints (tarsometatarsals (TMT) 1-3) are qualitatively different from lateral column joints (TMT 4-5) • Medial column joints more similar to inter-tarsal joints • Medial column joints need to be alignedand stiff • Lateral column joints need to be mobile

8. Midfoot Anatomy • Lisfranc’s Joint • articulation between the cuneifoms + cuboid (aka tarsus) and the bases of the five metatarsals

9. Midfoot Anatomy • Dorsal Capsule • Plantar Ligaments

10. Midfoot Anatomy • Lisfranc’s ligament: • large oblique ligament that extends from the plantar aspect of the medial cuneiform to the base of the second metatarsal • **there is no transverse metatarsal ligament between the first and second metatarsals)

11. Midfoot Anatomy • Interosseous ligaments: • Connect the metatarsal bases • ONLY 2-5, not 1-2 • Dorsal and plantar • Plantar are stronger and larger • Secondary stabilizers: • Plantar fascia • Peroneus longus • Intrinsincs

12. Mechanisms of Injury • Motor vehicle accidents 1/3-2/3 of cases • Incidence of lower extremity foot trauma has increased with the use of air bags • Crush injuries • Sports-related injuries are also occurring with increasing frequency

13. Mechanisms of Injury • 54 cadaver Limbs • Foot on the brake pedal • 2 groups: with and without plantarflexion. • Impacted at rate up to 16 meters/second • 3/13 of those in neutral position had injury-all at high rates • 65% of those in plantar flexion had injury including those at moderate speeds • Smith BR, Begeman PC, Leland R, Meehan R, Levine RS, Yang KH, King AI. A mechanism of injury to the forefoot in car crashes. Traffic Inj Prev. 2005 Jun;6(2):156-69

14. Mechanisms of Injury: Direct • Force applied directly to the TMT (Lisfranc’s) articulation on the dorsum of the foot.

15. Mechanisms of Injury: Indirect • Axial loading or twisting  hyper-plantarflexion and ligament rupture. • More common than direct.

16. Mechanisms of Injury • Indirect: • More common (typical athletic injury) • Rarely associated with open injury or vascular compromise • Direct: • Less common (crush) • Compartment syndrome more common than with indirect

17. Mechanisms of Injury: Associated Fractures • Forceful abduction of the forefoot may result in: • 2nd metatarsal base fracture • Compression fracture of the cuboid (“nut cracker”)

18. Mechanisms of Injury: Associated Fractures • Forceful abduction of the forefoot may result in: • Avulsion of navicular • Isolated medial cuneiform fracture

19. Foot Function and Shape • Plantigrade metatarsal heads • On heel rise, the [body weight] x 2.5 is supported by the metatarsal planes • Dense plantar ligaments prevent upward migration of metatarsals

20. Foot Function and Shape • Lateral column • Includes calcaneocuboid and 4,5 metatarsals • Shortening = abducto planus deformity

21. Foot Function and Shape • Medial column • Talonavicular joint, cuneiforms, medial 3 rays • Shortening = cavus foot

22. Treatment Principles • MUST • Restore alignment • Protect talonavicular motion • Protect 4,5 TMT motion • Motion of other joints not important • Arthrodesis OK for most small joints

23. Treatment Principles • Hindfoot: Protect ankle, subtalar, and talonavicular joints • Midfoot: restore length and alignment of medial and lateral “columns” • Forefoot: Even weight distribution

24. Midfoot Crush

25. Midfoot Crush • External Fixation • 4 mm Schanz pins in hindfoot • 2.5 mm terminally threaded Schanz pins in forefoot • Maintain length and alignment until swelling resolves

26. Midfoot Crush • Internal Fixation (Bridging) • Restore medial and lateral column • Restore anatomy of key joints • Span joints with 2.7 recon plate • Remove plate at 6 months

27. “Internal Fixator” Used as temporary fixation as in previous slide When mobile joints involved, can place multiple internal fixators Midfoot Crush

28. Midfoot Crush • Staged implant removal at six months post-op

29. Midfoot Crush: Outcomes • 25% of poly trauma patients do not return to work at 1 year • Lower extremity fractures cause more disability than upper • Those with foot injuries score worse in physical function, social function, pain, and physical and emotional role • Turchin JOT 1999; MacKenzie Am J Pub Health 1998.

30. Forefoot Crush

31. Forefoot Crush • Maintain alignment • Even weight distribution

32. Lisfranc Joint Injuries • Bony or ligamentous injury involving the tarsometatarsal joint complex • Named after the Napoleonic-era surgeon who described amputations at this level without ever defining a specific injury

33. Lisfranc Joint Injuries • Generally considered rare • 1 per 55,000 people per year • 15/5500 fractures • As index of suspicion increases, so does incidence • ~20% of these injuries overlooked • Especially in polytraumatized patients!!

34. Lisfranc Joint Injuries: Diagnosis • Requires a high degree of clinical suspicion • 20% misdiagnosed • 40% no treatment in the 1st week • Be wary of the diagnosis of “midfoot sprain”

35. Lisfranc Joint Injuries: Diagnosis • Appropriate mechanism • Midfoot pain and difficulty weight bearing • Swelling across dorsum of foot & plantar ecchymosis • Deformity variable due to possible spontaneous reduction

36. Lisfranc Joint Injuries: Diagnosis • Ecchymosis may appear late • Local tenderness at tarsometatarsal joints • OR edematous foot with poorly localized pain • Gentle stressing plantar/dorsiflexion and rotation will reveal instability

37. Lisfranc Joint Injuries: Diagnosis • Check neurovascular status • Possible compromise of dorsalis pedis artery • Deep peroneal nerve injury • COMPARTMENT SYNDROME

38. Lisfranc Joint Injuries: Evaluation • AP, Lateral and Oblique • Stress views • 2 plane instability • Standing views provide “stress” and may demonstrate subtle diastasis • Comparison views are very helpful

39. Lisfranc Joint Injuries: Evaluation • Oblique radiograph: • Medial base of the 4th metatarsal and medial margin of the cuboid should be aligned

40. Lisfranc Joint Injuries: Evaluation • MRI • More Radiology Income $$$$$$ • CT • Confusion, Total

41. Suspicious Signs • Step off at 2nd, gap between 1 and 2 • Fleck Sign • On the lateral view, the metatarsal should not be • dorsal to the cuneiform.

42. Suspicious Signs: Mills Line • Medial column line no longer intersects first metatarsal

43. Lisfranc Joint Injuries: Classification • Absolutely nobody cares • Simply determine: • Is this a fracture that enters the joint? • Or is this a disruption of the supportive ligaments? • Is there adequate resistance to dorsal translation of the metatarsals?

44. Lisfranc Joint Injuries: Treatment • Early recognition is the key to preventing long term disability • Anatomic reduction is necessary for best results: • Displacement >1mm or gross instability of tarsometatarsal, intercuneiform, or naviculocuneiform joints is unacceptable • Goal: obtain and/or maintain anatomic reduction

45. Lisfranc Joint Injuries: Treatment • Stiff joints: RIGID fixation • Flexible joints: FLEXIBLE fixation

46. Lisfranc Joint Injuries: Treatment • 1,2,3 TM joints have limited motion • Rigid fixation • 4,5 TM joints need mobility • Flexible or temporary fixation • Metatarsal heads need to meet the floor evenly • Bones heal, ligaments scar!

47. Lisfranc Joint Injuries: Treatment • Plantar tarsometatarsal ligaments intact: short leg walking cast • Unstable in 2 planes due to fracture at base: K-wire fixation • Unstable in 2 planes due to ligament rupture: rigid fixation or arthrodesis

48. Lisfranc Joint Injuries: Treatment • Naviculo-cuneiform not a mobile joint • Watch rotation of N-C joints • Primary fusion of immobile joints

49. Lisfranc Joint Injuries: Nonoperative Treatment • For nondisplaced injuries with normal weightbearing or stress x-rays • Short leg cast • 4 to 6 weeks NON weight bearing • Repeat x-rays to rule out displacement as swelling decreases • Total treatment 2-3 months

50. Lisfranc Joint Injuries: • Operative Treatment • Surgical emergencies: • 1. Open fractures • 2. Vascular compromise (dorsalis pedis) • 3. Compartment syndrome