Intramedullary Compression Fixation of Metacarpal and Phalangeal Fractures

Courtesy: Marco Guidi MD, University Hospitals Zurich, Switzerland

Introduction

• Intramedullary fixation is an emerging technique for the treatment of metacarpal and phalangeal fractures.
• It is considered a minimally invasive alternative to traditional plate fixation.
• However, plate fixation is still relevant, and treatment should always be based on proper fracture indication and pattern.

 

Limitations of Plate Fixation

Major complications

• Finger stiffness
• Extensor tendon adhesion and scarring
• Reduced tendon gliding over the plate

Mechanism

• Plates placed dorsally may interfere with:
  • Extensor tendon movement
  • Soft-tissue gliding
• This may result in:
  • Extensor lag
  • Postoperative stiffness

Evidence

• Earlier studies (e.g., Page & Stern, 1998) reported significant stiffness after plate fixation, particularly in proximal phalanx fractures.
• Although modern low-profile plates have reduced these complications, stiffness still remains a concern in some cases.

 

Emergence of Intramedullary Fixation

• Intramedullary screw fixation aims to:
  • Reduce soft-tissue dissection
  • Preserve tendon gliding
  • Allow earlier rehabilitation.

Early reports

• Bolton et al. (2010) reported successful treatment of subcapital metacarpal fractures using intramedullary screws.

Further development

• Francisco del Piñal popularized minimally invasive intramedullary fixation with excellent clinical outcomes.

 

Current Literature

• Over the past decade there has been a significant increase in publications regarding intramedullary fixation.
• Approximate literature trends:
  • ~85 studies on metacarpal intramedullary fixation
  • ~36 studies on phalangeal fractures.
• Biomechanical and clinical studies from several centers, including Zurich, have reported good functional outcomes.

 

Indications

Intramedullary screw fixation is most suitable for:

• Transverse fractures
• Short oblique fractures
• Selected comminuted fractures
• Fractures where minimal soft-tissue dissection is preferred

Not ideal for

• Long oblique fractures
• Spiral fractures
• Very proximal fractures
• Very distal fractures

Reason:

• Limited bone stock for adequate screw purchase.

 

Implants Used

Commonly used implants include:

• Headless compression screws (HCS)
• Self-drilling and self-tapping screws

Typical sizes:

• 3.0 mm screws – metacarpals
• 2.2 mm screws – phalanges
• 1.7 mm screws – small phalanges

 

Surgical Technique

General principles

• Perform closed or minimally invasive fracture reduction.
• A small incision is made over the joint.
• A guide K-wire is inserted into the intramedullary canal.
• A cannulated headless compression screw is advanced over the wire to stabilize the fracture.

 

Metacarpal Fracture Fixation

Entry point

• Through the dorsal aspect of the metacarpal head.

Technique steps

• Achieve fracture reduction.
• Insert guidewire through the metacarpal head.
• Advance into the intramedullary canal.
• Insert cannulated screw across the fracture.

Key technical considerations

• Measure metacarpal length carefully.
• Confirm position in AP and lateral fluoroscopic views.
• Ideally, the screw should cross the isthmus of the canal for stability.

 

Comminuted Fractures

• Some comminuted fractures may still be treated with intramedullary fixation.

Y-Strut Concept (Del Piñal)

• Uses two intramedullary screws to create a triangular or Y-shaped structural stability.
• Provides:
  • Improved stability
  • Better resistance to deforming forces.

 

Proximal Phalanx Fractures

Screw size

• Usually 2.2 mm screws

Technique options

1. Transarticular Antegrade Technique

• Guidewire inserted through metacarpal head ? proximal phalanx.
• Screw passed across fracture.

Drawback

• Potential cartilage injury at entry point.

 

2. Retrograde Intra-articular Technique

• Finger flexed at PIP joint.
• Screw inserted through phalanx head proximally.

Advantages:

• Simple
• Fast
• Frequently used technique.

Potential risks:

• Cartilage injury
• Central slip injury

 

Middle Phalanx Fractures

Antegrade extra-articular technique

• Entry from lateral side.
• Avoids cartilage injury.
• Suitable for transverse fractures.

Retrograde intra-articular technique

• Entry through distal interphalangeal joint.

Risks:

• Extensor tendon injury

 

Postoperative Management

Early mobilization

• Early protected motion encouraged.

Additional protection

• Buddy taping for 6 weeks to control rotational instability.

Rehabilitation

• Early hand therapy improves outcomes.

Follow-up protocol

• X-ray at 6 weeks
• Return to manual activity at ~8 weeks
• Office work possible within 1–2 weeks.

 

Outcomes

Systematic review findings:

• 958 fractures analyzed
• Mean operative time: ~26 minutes
• Fracture healing: 5–6 weeks
• Complication rate: ~3.2%

Most common complication

• Extension lag (~2%)

Overall results show:

• Good range of motion
• Rapid recovery.

 

Cartilage Damage

Studies report limited cartilage injury at entry point:

• 4–5% surface damage with larger screws.
• Other studies report 4–9% cartilage loss.

Clinical significance

• Long-term risk of post-traumatic osteoarthritis remains unclear.
• Long-term outcome studies are still limited.

 

Tendon Injury

Risk factors:

• Percutaneous insertion without visualization.

Evidence suggests:

• Mini-open approach (<1 cm incision) reduces extensor tendon injury compared with purely percutaneous technique.

 

Complications

Possible complications include:

• Screw protrusion
• Screw breakage
• Rotational instability
• Loss of fracture length
• Extension lag
• Rare osteonecrosis of phalanx head

 

Contraindications

Intramedullary fixation should not be used for:

• Long oblique fractures
• Spiral fractures
• Highly comminuted intra-articular fractures
• Open growth plates
• Active infection
• Subacute fractures.

 

Advantages of Intramedullary Fixation

• Minimally invasive
• Short operative time
• Less soft-tissue disruption
• Lower postoperative edema
• Faster rehabilitation
• Adequate stability for early motion.

 

Limitations

• Not suitable for all fracture patterns.
• Potential cartilage injury during screw entry.
• Removal of broken screws can be technically challenging.

 

Key Take-Home Messages

• Intramedullary screw fixation is a safe and effective technique for selected metacarpal and phalangeal fractures.
• It offers minimally invasive stabilization with early rehabilitation.
• Appropriate patient and fracture selection is essential for optimal outcomes.
• Plate fixation still remains necessary for complex fracture patterns.