What is the best treatment approach for an adult patient with a nonunion zone 1 base of fifth metatarsal fracture and no significant medical history?

Treatment of Nonunion Zone 1 Base of Fifth Metatarsal Fracture

Percutaneous intramedullary screw fixation without fracture site preparation is the definitive treatment for zone 1 nonunion of the fifth metatarsal base, achieving union in essentially all cases by 3 months. 1

Surgical Management: The Evidence-Based Approach

Primary Treatment Recommendation

• Percutaneous screw fixation is highly effective for zone 1 nonunions, with a 100% union rate demonstrated in prospective studies (30/30 patients achieving union, with 29/30 united by 6 weeks). 1

• Zone 1 injuries should be fixed using a 3-mm headless compression screw inserted percutaneously under radiographic guidance. 1

• Fracture site preparation is not necessary—the screw alters the strain at the fracture site, promoting fibrous-to-osseous conversion without requiring debridement or bone grafting in most cases. 1

Surgical Technique Specifics

• The starting point should be proximal and dorsal (high and inside position) to avoid the peroneus brevis insertion and minimize risk to the sural nerve. 2

• Use fluoroscopy with multiple views (anteroposterior, lateral, and oblique) to confirm proper guidewire and screw placement throughout the procedure. 2

• Make the incision 1-3 cm proximal to the fifth metatarsal base to avoid soft-tissue tension and wound complications. 2

• The percutaneous approach minimizes soft-tissue damage, infection rates, and operative time compared to open techniques. 2

Alternative Surgical Approach for Complex Cases

• Endoscopic bone grafting may be considered for painful intra-articular nonunions where the fifth metatarsal-cuboid articulation needs assessment or when intra-articular pathology is suspected. 3

• This technique allows thorough debridement and bone grafting without extensive soft-tissue dissection while permitting arthroscopic evaluation of the joint. 3

Expected Outcomes

Union Rates and Timing

• All patients achieve union by 3 months post-fixation, with the vast majority (97%) uniting by 6 weeks. 1

• Complete symptom resolution occurs in all successfully treated patients. 1

• Full unassisted weight-bearing without pain typically begins at approximately 10 weeks postoperatively. 4

Functional Recovery

• Pain scores improve dramatically, from a preoperative mean of 5.4 to postoperative mean of 1.0 on standard pain scales. 4

• Return to prior activity levels occurs at an average of 8-9 weeks following surgery. 5

Postoperative Protocol

Immediate Postoperative Period (Weeks 0-2)

• Non-weight-bearing in a soft wrap and postoperative boot for the first 2 weeks. 2

• Keep the incision clean and dry with frequent elevation of the foot/ankle. 2

Progressive Weight-Bearing (Weeks 2-6)

• Suture removal at 2-6 weeks with initiation of ankle range-of-motion exercises. 2

• Progressive weight-bearing protocol: 25% at week 3,50% at week 4,75% at week 5, and 100% at week 6. 2

• Use the postoperative boot for all weight-bearing ambulation with crutches during the transition period. 2

Advanced Recovery (Weeks 6-12)

• Increase walking and physical therapy while continuing strengthening exercises. 2

• Begin pool or treadmill activity at weeks 8-12 and progressively increase thereafter. 2

• Radiographic union is expected between weeks 6-10. 2

Critical Pitfalls to Avoid

Surgical Technique Errors

• Do not place the incision too close to the proximal fifth metatarsal—this creates unnecessary soft-tissue tension and increases wound complication risk. 2

• Avoid inadequate soft-tissue retraction—protecting the sural nerve is paramount during screw insertion. 2

• Do not allow immediate weight-bearing—this compromises healing and increases nonunion risk. 2

Patient Selection Considerations

• This technique is not recommended for comminuted fractures or proximal-split fracture patterns—these require plate fixation or alternative approaches. 2

• Poor surgical candidates include those with neuropathic feet, local infection, severe vascular insufficiency, or significant comorbidities that make surgery dangerous. 2

Why Surgery Over Conservative Management for Nonunion

• Conservative management has already failed by definition in a nonunion—continued immobilization is unlikely to achieve union and prolongs disability. 1

• Nonunion causes considerable pain with high morbidity and loss of work, making surgical intervention necessary for functional recovery. 1, 4

• The average time from injury to treatment in nonunion cases is 5.9 months (range 3-36 months), indicating that adequate conservative treatment time has elapsed. 1

Complications and Their Management

• Complication rates are low with this technique, but potential issues include deep infection, delayed wound healing, and sural neuroma formation. 4

• No complications were reported in the largest prospective series of zone 1 nonunions treated with this technique. 1