Treatment of Intra-articular Fracture at Base of Fifth Metacarpal with Minimal Displacement
For minimally displaced intra-articular fractures at the base of the fifth metacarpal, removable splinting for 3-4 weeks with early active finger motion exercises is the appropriate treatment approach. 1, 2
Initial Management
- Removable splinting is the treatment of choice for minimally displaced intra-articular fractures, as recommended by the American Academy of Orthopaedic Surgeons for minimally displaced fractures 3, 2
- Immobilization should be maintained for 3-4 weeks 2
- The splint should position the metacarpophalangeal joint in 60-90 degrees of flexion with fingers in full extension 4, 5
- Begin active finger motion exercises immediately after diagnosis to prevent stiffness, which is the most functionally disabling complication 1, 2
Critical Threshold for Surgical Intervention
You must carefully assess displacement parameters, as the fifth metacarpal base fracture behaves similarly to a Bennett fracture and is inherently unstable 6, 7. Surgical treatment becomes mandatory if any of the following are present:
- Displacement >3mm 1, 2
- Dorsal tilt >10 degrees 1, 2
- Any loss of joint congruity on radiographs 1
- Malrotation of any degree 4, 5
- Shortening >5mm 4, 5
Rationale for Treatment Decision
The evidence strongly supports that inadequate reduction of intra-articular fractures at the fifth metacarpal base leads to pain, functional disability, and early osteoarthritic changes 6, 7. Multiple studies emphasize that this fracture pattern—often called the "mirrored Bennett fracture"—cannot be reliably maintained with closed reduction alone if significantly displaced 7, 8. However, when truly minimally displaced, conservative management with removable splinting avoids surgical risks while allowing early motion 3, 2.
Follow-up Protocol
- Obtain radiographs at 3 weeks post-injury to assess for delayed displacement that would require surgical intervention 1, 2
- Repeat imaging at the time of immobilization removal to confirm adequate healing 1, 2
- Monitor for immobilization-related complications (skin irritation, muscle atrophy), which occur in approximately 14.7% of cases 2, 9
Common Pitfalls to Avoid
- Do not rely on closed reduction and casting for displaced fractures—studies demonstrate this approach fails to maintain reduction in fifth metacarpal base fractures 4, 5
- Do not underestimate the degree of displacement—even seemingly minor intra-articular step-offs can lead to post-traumatic arthritis 1, 6
- Do not immobilize for prolonged periods—this leads to joint stiffness, the most disabling complication 1, 2
- Do not skip the 3-week radiographic follow-up—delayed displacement requiring surgical intervention can be missed 1, 2
Surgical Approach if Indicated
If displacement exceeds the thresholds above, closed reduction with percutaneous pinning using fluoroscopic guidance is the preferred surgical method 6, 8. Open reduction with multiple Kirschner wire fixation is reserved for comminuted fractures where closed restoration of the articular surface is not feasible 6. Studies report good functional outcomes with surgical fixation and no arthritic changes at follow-up 6, 8.