Femoral Neck Fracture Fixation: Comparing DHS, MCS, and FNS – Latest Advances in Surgical Treatment

Femoral neck fractures remain one of the most challenging injuries in orthopedic trauma surgery. Despite advances in implant design and surgical techniques, complications such as nonunion, fixation failure, femoral neck shortening, and avascular necrosis (AVN) of the femoral head continue to affect patient outcomes.

Selecting the optimal fixation method requires careful evaluation of fracture pattern, patient age, bone quality, displacement, and biomechanical stability. Today, the three most commonly used fixation techniques are:

• Dynamic Hip Screw (DHS)

• Multiple Cannulated Screws (MCS)

• Femoral Neck System (FNS)

This article reviews the latest evidence, indications, advantages, and limitations of each technique to help surgeons make informed treatment decisions.

Why Femoral Neck Fractures Are Challenging

Risk of Femoral Head Blood Supply Disruption

The femoral head receives its blood supply primarily from:

• Superior retinacular arteries

• Inferior retinacular arteries

• Anterior retinacular arteries

When a femoral neck fracture becomes displaced, these vessels may be damaged, significantly increasing the risk of:

• Femoral head avascular necrosis (AVN)

• Delayed union

• Nonunion

• Fixation failure

Because preservation of the native hip is particularly important in younger and active patients, internal fixation remains the preferred treatment whenever feasible.

Classification Systems That Guide Treatment Decisions

Garden Classification

The Garden classification remains one of the most widely used systems for determining whether fixation or arthroplasty is appropriate.

Garden Type I

• Incomplete valgus impacted fracture

• Generally stable

• Excellent candidate for internal fixation

Garden Type II

• Complete fracture without displacement

• Stable fracture pattern

• Internal fixation typically recommended

Garden Type III

• Complete fracture with partial displacement

• Treatment depends on patient age, bone quality, and reduction quality

Garden Type IV

• Completely displaced fracture

• Highest risk of AVN and nonunion

• Arthroplasty is often considered, especially in elderly patients

Pauwels Classification

Pauwels classification evaluates fracture verticality and shear force.

Pauwels Type I

• Fracture angle <30°

• Relatively stable

• Excellent fixation outcomes

Pauwels Type II

• Fracture angle 30°–50°

• Moderate instability

Pauwels Type III

• Fracture angle >50°

• High shear stress

• Increased risk of fixation failure

The more vertical the fracture line, the stronger the fixation construct required.

Patient Selection for Internal Fixation

Key Factors to Consider

Successful fixation depends on multiple variables:

• Degree of fracture displacement

• Pauwels angle

• Bone quality

• Patient age

• Femoral neck posterior tilt

• Functional demands

Posterior Tilt Matters

Recent studies suggest that a posterior tilt greater than 20° is one of the strongest predictors of fixation failure and reoperation.

Timing of Surgery and Reduction Techniques

Early Surgery Improves Outcomes

Evidence indicates that surgery performed within 24 hours after injury may reduce the risk of:

• Nonunion

• Femoral head ischemia

• Complications associated with prolonged immobilization

Early reduction and fixation remain critical components of treatment.

Closed Reduction Is Preferred

Benefits of Closed Reduction

• Less soft tissue disruption

• Lower infection risk

• Preservation of blood supply

• Faster recovery

Risks of Open Reduction

Recent studies have shown that open reduction does not necessarily improve reduction quality and may increase reoperation rates due to additional surgical trauma.

For most cases, surgeons should attempt anatomical closed reduction before considering open techniques.

Dynamic Hip Screw (DHS): Strong Fixation for Unstable Fractures

What Is DHS?

The Dynamic Hip Screw (DHS) is a sliding hip screw system connected to a side plate that provides strong resistance against shear forces.

Ideal Indications

• Pauwels II and III fractures

• Vertically oriented fractures

• Unstable femoral neck fractures

Advantages of DHS

Superior Shear Resistance

Biomechanical studies consistently demonstrate that DHS provides:

• Excellent stability

• Strong resistance to vertical shear forces

• Lower nonunion rates compared with multiple screw fixation in vertical fracture patterns

Reliable Clinical Outcomes

DHS remains a trusted option for high-risk fractures where stability is the primary concern.

Limitations of DHS

• Larger surgical exposure

• More soft tissue dissection

• Greater blood loss

• Increased operative time

While highly stable, DHS is less minimally invasive than newer fixation systems.

Multiple Cannulated Screws (MCS): A Minimally Invasive Standard

What Is MCS?

Multiple Cannulated Screws (MCS) involve placement of two or three parallel screws across the femoral neck fracture.

This technique has been the traditional standard for decades.

Ideal Candidates

MCS is best suited for:

• Young patients

• Good bone quality

• Garden I and II fractures

• Minimally displaced fractures

Advantages of MCS

Minimally Invasive Procedure

Benefits include:

• Small incisions

• Minimal soft tissue disruption

• Reduced blood loss

• Short operative time

Preservation of Blood Supply

Because surgical exposure is limited, vascular injury may be minimized.

Limitations of MCS

Reduced Stability in Unstable Fractures

Complication rates increase significantly in:

• Garden III fractures

• Garden IV fractures

• Pauwels III fractures

• Posterior tilt >20°

Common problems include:

• Femoral neck shortening

• Screw migration

• Loss of reduction

• Nonunion

Femoral Neck System (FNS): Combining Stability and Minimal Invasiveness

What Is the Femoral Neck System?

The Femoral Neck System (FNS) is a newer fixation platform designed specifically for femoral neck fractures.

It combines:

• Central fixation bolt

• Anti-rotation screw/blade

• Small side plate

This design provides both angular stability and rotational control.

Biomechanical Advantages of FNS

Enhanced Rotational Stability

Compared with cannulated screws, FNS offers:

• Better resistance to rotation

• Improved fracture compression

• Reduced femoral neck shortening

Stability Comparable to DHS

Biomechanical testing demonstrates that FNS can achieve fixation strength similar to DHS while requiring a much smaller surgical exposure.

Clinical Benefits of FNS

Early clinical studies have reported:

• Lower complication rates

• Reduced femoral neck shortening

• Better early functional scores

• Faster mobilization

• Less postoperative pain

For many surgeons, FNS has become an attractive option for unstable fractures in younger patients.

Limitations of FNS

Despite promising results, several challenges remain:

• Higher implant cost

• Limited long-term follow-up data

• More complex implant removal

• Need for additional high-quality comparative studies

Emerging Adjunctive Techniques

Valgus Intertrochanteric Osteotomy

Valgus-producing osteotomy can convert vertical shear forces into compressive forces.

Indications

• Young patients

• Pauwels III fractures

• Failed fixation cases

• High-risk nonunion patterns

This technique remains valuable in selected patients seeking joint preservation.

Medial Buttress Plate Augmentation

Anterior or medial buttress plating has gained attention as a method to improve stability in vertical fractures.

Potential Benefits

• Increased resistance to shear forces

• Enhanced medial cortical support

• Improved construct stiffness

However, current clinical evidence remains limited, and routine use is not yet universally recommended.

DHS vs MCS vs FNS: Quick Comparison

Current Recommendations

Stable Fractures

For:

• Garden I

• Garden II

• Low-angle Pauwels fractures

Multiple Cannulated Screws (MCS) remain an effective and minimally invasive solution.

Unstable Fractures

For:

• Garden III–IV

• Pauwels III

• High posterior tilt fractures

Current evidence increasingly supports:

1. Femoral Neck System (FNS)

2. Dynamic Hip Screw (DHS)

These systems provide superior biomechanical stability and lower fixation failure rates.

Future Directions

The Femoral Neck System represents one of the most significant recent innovations in femoral neck fracture fixation.

Although early outcomes are encouraging, future research should focus on:

• Long-term implant survival

• Rates of avascular necrosis

• Implant removal strategies

• Cost-effectiveness analyses

• Identification of optimal patient populations

As evidence continues to accumulate, FNS may become the preferred fixation method for many unstable femoral neck fractures.

Conclusion

Femoral neck fractures require individualized treatment planning based on fracture morphology, patient factors, and biomechanical demands.

Key takeaways include:

• MCS remains an excellent option for stable, minimally displaced fractures.

• DHS provides powerful fixation for vertical and unstable fracture patterns.

• FNS combines the biomechanical strength of DHS with the minimally invasive advantages of cannulated screws.

• For unstable femoral neck fractures, DHS and FNS are increasingly favored over traditional multiple screw fixation.

As implant technology evolves, the goal remains unchanged: achieving stable fixation, preserving femoral head viability, and restoring patients to their pre-injury level of function as quickly and safely as possible.