| Trauma to the Foot and Ankle: Keeping the Surgeon Stable (G) - Index

II. Jones Fractures of the 5th Metatarsal

Robert B. Anderson, MD

I. Definition = fracture of the metaphyseal-diaphyseal junction at or distal to the 4th and 5th metatarsal articulation

II. Zones 1-3

a) Zone 1 – Tuberosity avulsion fractures – typically oblique fracture line

b) Zone 2 – True Jones fracture – transverse fracture line

c) Zone 3 – Diaphyseal stress fractures

d) Zones 2 & 3 have guarded potential for healing related to vascular watershed area and factors placing added load to this area; often treated the same

III. Treatment of Jones fractures

a) Nonoperative

i. NWB for 6 wks (Torg)

ii. 72-75% heal in 5 months

iii. 50% fail to heal or refracture (Quill)

b) Operative

i. Indications (threshold decreasing?)

1. Athlete with acute or stress fx

2. Nonunion

3. Refracture

4. Acute or stress fracture in presence of cavovarus foot/lateral overload

ii. Operative goals

1. Expedite healing

2. Quicker recovery

3. Easier rehab

4 Decreased risk of refracture

iii. Surgical technique

1. Axial screw fixation is the gold standard but no studies with Level 1 or 2 evidence

a. Popularized by J DeLee

b. Plates work but are prominent and require removal with subsequent risk for refracture

2. Low morbidity – percutaneous technique in primary situations

a. Open bone grafting for revisions

3. Select largest solid screw that “comfortably” fits canal

a. Studies only suggest screw must be larger than 4.0 (Porter)

b. No definitive answer on cannulated vs not

c. Headless variable pitch screw has less pull out strength but equal bending strength to 6.5 cancellous lag screw (Sides SD, FAI, 2006)

d. Jones fracture-specific screws now available

4. Surgical technique

a. Outpatient; regional anesthesia; calf tourniquet optional

b. Enter the canal “high and inside” on the tuberosity – need to account for “curved” diaphysis

i. “Hug the cuboid”

ii. Blunt dissection to protect sural nerve

c. Cannulated assisted

i. Option to use a solid 3.2mm drill bit to “ream” the canal free-hand once the proximal canal is opened with a cannulated system

ii. Prevents perforation of cortex or cutting across guide wire

1. Advance on reverse drilling

iii. Adjusts for less than ideal entry site

d. Tap to determine screw diameter and length

i. 4.5, 5.5, 6.5mm – partially threaded

ii .Most men require a 5.5mm screw to obtain distal intramedullary cortical purchase

iii. Excessively large diameter screw may distract fracture site

iv. Threads just past the fracture

1. Longer screw may attempt to “straighten” bone and lead to lateral gapping

v. Headless variable pitch screw has less pull out strength but equal bending strength to 6.5 cancellous lag screw (Sides SD, FAI, 2006)

5. Option to inject biologic (DBM + bone marrow aspirate) or stem cells

a. Consider if lateral/plantar gap present after screw insertion

b. Aspirate from iliac crest or tibia – need 2-4cc volume

iv. Typical postop management

1. NWB 1-2 weeks, then walker boot for 2-4 wks

2. Pool therapy/bike good cross-training rehab tools

3. Run in stiffened shoewear/orthosis once clinically nontender

4. Return to play when nontender – usually 6-8 weeks (x-ray healing lags behind)

5. Leave screw indefinitely - high incidence of refracture after screw removal (Josefsson, Clin Orthop 299:252, 1994)

IV. Complications of intramedullary screw fixation

a) Infection

b) Sural nerve injury

c) Distal cortical perforation (not ”high and inside” or screw too long)

d) Prominent screw head – (not “high and inside” – entered too lateral)

e) Recurrent fracture/nonunion (often with hardware failure)

i. Not a new problem

1. Wright AJSM ’00

2. Larsen AJSM ‘02

3. Anderson: our own review noted a 8% nonunion rate in elite athletes – often asymptomatic

ii. Athlete/parents must understand this risk when early postop play decisions are made (accelerated rehab)

iii. CT scan often necessary to confirm degree of nonunion

1. Need to differentiate from a persistent plantar-lateral gap

iv. Be critical of index surgery

1. Type/size/length of screw

a. Small cannulated screws may bend/break

b. Long screws may “stress shield” proximal metatarsal or create lateral gapping

2. Location/direction of fracture

a. Axial screws for transverse fractures

b. Bicortical screws may be better for very proximal oblique fractures

3. Foot posture

a. Cavovarus/metatarsus adductus creates lateral overload

v. Observe/protect if asymptomatic

1. Okay to play and may do well if well positioned and fitted screw of adequate size

vi. If symptomatic refracture - manage initially with rest/stimulator

1. Other options available include injection of biologic or high energy shockwave

a. Helpful if time constraint

vii. Persistent or unstable nonunion: open bone grafting and screw exchange

1. Place larger solid screw

2. Autogenous bone graft

a. Prefer non-weightbearing location due to risk for stress fracture

i. Iliac crest – use power trephine

3. +/- address lateral overload (depends on index technique)

a. 1st metatarsal or calcaneal osteotomy

b. Use bone removed for bone grafting of nonunion

4. Bone stimulator postop

5. Extended period of non-weightbearing (usually 6 weeks)

6. Repeat CT at 10-12 weeks to assess union

7. RTP when fully united by CT and asymptomatic

viii. Failed revision surgery - reassess for hindfoot varus/lateral overload; consider Vitamin D deficiency

1. Dorsiflexion 1st metatarsal or calcaneal osteotomy or both

2. If normal foot posture?

a. Anecdotal reports of cuboid osteotomy and plantar condylectomy of 5th metatarsal


Bibliography

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2. Carpe L: Fractures of the fifth metatarsal bone, with reference to delayed union. Ann Surg 1927; 86:308-320.

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14. Shah SN, et al: Intramedullary screw fixation of proximal fifth metatarsal fractures: a biomechanical study. Foot Ankle Int 2001; 22:581-584.

15. Sides SD, et al: Bending stiffness and pull-out strength of tapered variable pitch screws and 6.5-mm cancellous screws in acute Jones fractures. FAI 2006; 27, 821- 25.

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