Jones Fractures

Fifth Metatarsal Anatomy - Zone 2

Zone 2 - The Critical Location

Anatomical Boundaries:

• Proximal: Level of 4-5 intermetatarsal articulation
• Distal: Junction of metaphysis and diaphysis
• Key feature: Fracture line extends INTO the 4-5 intermetatarsal joint

Watershed Blood Supply - Why Jones Fractures Don't Heal

Mechanism of Injury

Primary Mechanisms:

1. Adduction force on planted forefoot
2. Vertical loading with heel off ground
3. Repetitive stress in athletes (acute-on-chronic)

Biomechanical Factors:

• Fifth metatarsal acts as lever arm during push-off
• Peroneus brevis creates bending moment
• Lateral column overload in hindfoot varus

Risk Factors:

• High-level athletes (running, cutting sports)
• Hindfoot varus alignment
• Tight gastrocnemius
• Previous fifth metatarsal injury
• Inadequate footwear

Radiographic Findings:

• Sharp, well-defined fracture line
• No periosteal reaction
• No medullary sclerosis
• Narrow fracture gap

Treatment Options:

Non-Athletes:

• Non-weight-bearing short leg cast
• 6-8 weeks immobilization
• Accept 25-50% nonunion rate

Athletes:

• Primary intramedullary screw fixation
• Faster union (8-10 weeks vs 15+ weeks)
• Lower nonunion rate (under 5% vs 25-50%)
• Earlier return to sport

Proper technique and attention to detail ensure optimal outcomes.

Radiographic Findings:

• Widened fracture line
• Periosteal new bone formation
• Early medullary sclerosis
• Previous treatment failure common

Treatment:

• Intramedullary screw fixation
• Consider bone grafting
• Some surgeons curet the fracture site
• Expected healing 10-12 weeks
• Higher refracture risk than Type I

Key Point: Bone graft improves healing in delayed union - autograft from iliac crest or proximal tibia.

Radiographic Findings:

• Complete medullary sclerosis
• Obliterated medullary canal
• Wide, irregular fracture gap
• Periosteal reaction/callus

Treatment:

• Curettage of medullary canal (essential)
• Bone grafting (autograft preferred)
• Intramedullary screw fixation
• Some use plate fixation if canal severely obliterated
• Expected healing 12-16+ weeks

Alternative: Plantar plating if medullary canal cannot accommodate screw.

Indications: Sedentary patients, low functional demands, Torg Type I acute fractures, patient accepts 25-50% nonunion risk.

Protocol: Short leg non-weight-bearing cast with strict non-weight-bearing for 6-8 weeks. Serial radiographs every 2-3 weeks. Gradual weight-bearing when radiographic healing seen. Total treatment time 12-20 weeks.

Expected Outcomes: Union rate 50-75%, time to union 15-20 weeks, return to sport 4-5 months if healing occurs.

Indications: Athletes (any level), high functional demands, Torg Type II-III, failed conservative treatment, desire for faster return to activity.

Technique Keys (SCREW): Size matters (5.5mm minimum diameter), Cannulated technique over guidewire, Ream if needed (overream by 0.5mm only), Entry point at tip of tuberosity (high and medial), Wedge screw into far cortex to engage plantar bone.

Why Athletes Need Surgery: Faster return to sport (8-10 weeks vs 15+ weeks), lower nonunion rate (under 5% vs 25-50%), more predictable healing.

Timeline: Week 0-2 involves non-weight-bearing in posterior splint. Week 2-6 uses CAM boot with progressive weight-bearing. Week 6-8 transitions to athletic shoe with full weight-bearing. Week 8-10 begins sport-specific training with return to play.

Patient Setup: Supine on radiolucent table with bump under ipsilateral hip. Foot must be accessible for fluoroscopy.

Equipment: Fluoroscopy (C-arm), 5.5mm or 6.5mm cannulated screws, guidewires, cannulated drill, and countersink.

Surgical Steps: (1) Approach via direct lateral incision over tuberosity (2-3cm), protecting sural nerve. (2) Entry point critical at tip of tuberosity ("high and medial"). (3) Introduce guidewire under fluoroscopy, confirm central position. (4) Measure screw length, ream if needed (overream 0.5mm). (5) Insert largest screw that fits (5.5mm minimum), engage far cortex. (6) Final check with fluoroscopy AP/lateral/oblique, confirm compression.

When Required: Torg Type II with significant sclerosis, Torg Type III nonunion, or revision surgery.

Graft Options: (1) Iliac crest autograft is the gold standard. (2) Proximal tibia autograft offers less morbidity. (3) Calcaneus autograft allows same operative field access.

Technique: Curet sclerotic bone from medullary canal, pack morselized graft into canal, may place graft around fracture site, then insert intramedullary screw.

Entry Point Critical: Too plantar risks sural nerve injury, too dorsal causes eccentric screw placement. Aim for center of medullary canal.

Screw Selection: A large (5.5mm or greater) solid screw is recommended in elite athletes; undersized hardware is a recognised cause of refracture and nonunion (Hunt and Anderson 2011). Solid screws are biomechanically stronger than cannulated screws. The screw must cross and compress the fracture site adequately and "fit and fill" the canal.

Final Check: Fluoroscopy AP, lateral, and oblique views to confirm adequate fracture compression, no joint penetration, and countersink head to avoid prominence.

Risk Factors: Conservative treatment (25-50% rate), Torg Type II-III at presentation, inadequate immobilization, early weight-bearing, smoking, and diabetes.

Treatment: Surgical fixation with bone graft, curettage of sclerotic bone, and consideration of larger screw or plate fixation.

Risk Factors: Small screw diameter (under 5mm), early return to sport, hardware removal, and residual varus alignment.

Prevention: Use adequate screw size (5.5mm minimum), delay return to sport until healed, address biomechanical factors, and consider leaving hardware in place long-term.

Complications: Prominent screw head may need removal after healing. Screw backing out requires revision fixation. Screw breakage is rare with adequate size.

Sural Nerve Injury: Caused by entry point too plantar or retraction injury. Prevention involves entry at TIP of tuberosity with careful soft tissue handling and direct visualization.

Week 0-2: Posterior splint with non-weight-bearing. Elevation and ice for swelling control.

Week 2-6: CAM boot with progressive weight-bearing in boot. ROM exercises out of boot. Pool therapy if available.

Week 6-8: Transition to athletic shoe with full weight-bearing. Progressive strengthening including stationary bike and swimming.

Week 8-10: Sport-specific training begins with cutting and jumping progression. Return to play when criteria met.

Criteria for Return to Sport: (1) Pain-free with sport-specific activities, (2) Full range of motion, (3) Normal strength demonstrated by single-leg hop test, (4) Radiographic evidence of healing with bridging callus, (5) Typically 8-10 weeks post-operatively.

Comparison: Surgical approach allows 8-10 weeks return to sport, while conservative treatment requires 15-20+ weeks if healing occurs. This timing difference explains why athletes choose surgery.

Athletes require earlier return to sport, making surgical fixation the preferred option for competitive and active individuals.