How should a base of the fifth metatarsal fracture be managed in adults, considering fracture zone (avulsion zone I versus Jones zone II versus zone III), degree of displacement, activity level, and comorbidities such as diabetes, smoking, peripheral vascular disease, or chronic steroid use?

Management of Base of Fifth Metatarsal Fractures in Adults

For Zone I (avulsion) fractures, treat with a hard-soled shoe or CAM-walker boot allowing immediate weight-bearing as tolerated; for Zone II (Jones) fractures in active patients or those with high-risk features (diabetes, smoking, peripheral vascular disease, chronic steroid use), proceed directly to intramedullary screw fixation rather than conservative management to avoid the high risk of nonunion and prolonged disability. 1, 2

Initial Imaging and Diagnosis

• Obtain standard three-view ankle radiographs (anteroposterior, lateral, and mortise) that include the base of the fifth metatarsal distal to the tuberosity to characterize fracture location, displacement, and involvement of the cubometatarsal joint 3
• The base of the fifth metatarsal must be visualized on ankle films because isolated foot radiographs miss associated ankle pathology in inversion injuries 3

Fracture Zone Classification and Treatment Algorithm

Zone I: Tuberosity Avulsion Fractures (Most Common)

Non-operative management is appropriate for all undisplaced or minimally displaced (<2 mm) avulsion fractures:

• Use either a hard-soled shoe or CAM-walker boot with immediate weight-bearing as tolerated—both achieve similar functional outcomes, though the CAM-walker demonstrates slightly faster radiographic healing (7.2 vs 8.6 weeks) 4
• A soft Jones dressing is superior to rigid casting, allowing return to activity in 33 days versus 46 days without compromising union 5
• Surgical fixation with intramedullary screw, tension band, or plate is indicated when displacement exceeds 2 mm or when more than 30% of the cubometatarsal joint surface is involved 6, 2
• All avulsion fractures demonstrate radiographic healing by 65 days (average 44 days) and patients return to full activity within 96 days 5

Zone II: Jones Fractures (Metaphyseal-Diaphyseal Junction)

This zone carries the highest risk of nonunion and delayed healing due to watershed blood supply:

• For active patients, athletes, or those with any high-risk comorbidity (diabetes, smoking, peripheral vascular disease, chronic steroid use), recommend primary intramedullary screw fixation to reduce nonunion risk and accelerate return to activity 1, 2
• For sedentary patients with acute undisplaced Jones fractures (Torg Type I), non-operative management with non-weight-bearing cast immobilization for 6-8 weeks is acceptable, though healing time is prolonged 2
• Torg Type II fractures (delayed union with widened fracture line) can be treated conservatively only in low-demand patients; active individuals require surgery 2
• Torg Type III fractures (established nonunion) mandate operative fixation due to high complication rates 2

Zone III: Proximal Shaft Fractures

• Non-displaced or minimally displaced shaft fractures (<3-4 mm displacement, <10° angulation) can be managed non-operatively with protected weight-bearing 2
• Surgical fixation with percutaneous K-wires, plate, or screw is indicated when displacement exceeds 3-4 mm or angulation exceeds 10° 2

Comorbidity-Specific Modifications

Patients with diabetes, smoking history, peripheral vascular disease, or chronic steroid use face substantially elevated nonunion risk:

• Lower the threshold for surgical intervention in these populations—consider operative management even for minimally displaced Zone II fractures 1
• These patients require more aggressive monitoring for delayed healing and should not undergo prolonged trials of conservative management 6

Pain Management and Early Mobilization

• Provide multimodal analgesia immediately with scheduled acetaminophen; avoid NSAIDs in elderly patients due to renal and gastrointestinal risks 7, 8
• Begin active range-of-motion exercises of all uninjured toes and ankle joints within 3 days to prevent debilitating stiffness, which becomes extremely difficult to treat after fracture healing 7
• Splints or boots must not restrict motion of uninjured joints 7

Osteoporosis Evaluation in Patients Over 50 Years

A fifth metatarsal fracture in older adults may represent an underlying fragility fracture requiring comprehensive bone health assessment:

• Order serum vitamin D, calcium, and parathyroid hormone levels during the initial visit and arrange outpatient DEXA scan with referral to a bone health clinic 7, 8
• Consider initiating anti-osteoporotic therapy even before DEXA results in patients with typical fragility fracture patterns 8
• Implement fall prevention programs including balance training, which reduce subsequent falls by approximately 20% 3, 7
• Adequate calcium intake (1000-1200 mg/day) and vitamin D supplementation (800 IU/day) are associated with 15-20% reduction in non-vertebral fractures 3

Common Pitfalls to Avoid

• Do not treat Jones fractures (Zone II) conservatively in active patients or those with risk factors—the nonunion rate is unacceptably high and leads to prolonged disability 1, 2
• Do not neglect osteoporosis evaluation in patients over 50—untreated bone loss increases the risk of subsequent hip or vertebral fractures by 2-4 fold within one year 7
• Do not delay mobilization of uninjured joints awaiting complete pain resolution—stiffness develops rapidly and is difficult to reverse 7
• Do not use rigid casting for simple avulsion fractures—soft dressings or functional boots allow faster return to activity without compromising union 5

Follow-Up Protocol

• Assess clinical healing, weight-bearing tolerance, and pain at 4,8, and 12 weeks or until asymptomatic and able to return to prior activity level 4
• Monitor for persistent pain during follow-up, which warrants investigation for delayed union, nonunion, or refracture—these are the most common complications of fifth metatarsal base fractures 6
• In elderly patients, screen for pressure injuries, nutritional status, and cognitive function at each visit 8
• Ensure systematic monitoring of osteoporosis treatment adherence through dedicated follow-up 7