Kuzyk, J Orthop Trauma 2012 - Femoral Head Lag Screw Position for Cephalomedullary Nails: A Biomechanical Analysis - Article Summary

Femoral Head Lag Screw Position for Cephalomedullary Nails: A Biomechanical Analysis

Kuzyk, Schemitsch, et al.·J Orthop Trauma·2012·160 citations·Biomechanical study

Purpose

The purpose of this study was to determine if lag screw position affects the biomechanical properties of a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Methods

Unstable peritrochanteric fractures were created in 30 synthetic femurs and repaired with Long Gamma 3 Nails using one of 5 lag screw positions: superior, inferior, anterior, posterior, or central.
Radiographic measurements including tip-apex distance and a calcar referenced tip-apex distance were calculated from anteroposterior and lateral radiographs.
Specimens were tested for axial, lateral bending, and torsional stiffness and then loaded to failure in the axial position.
Analysis of variance and linear regression were used for statistical analysis.

Results

The inferior lag screw position had significantly greater mean axial stiffness than superior (P < 0.01), anterior (P = 0.02), and posterior (P = 0.04) positions.
Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared with other lag screw positions (P < 0.01 all 4 pairings).
No statistical differences were noted for lateral bending stiffness.
Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (P < 0.01 and P = 0.02) and posterior (P < 0.01 and P = 0.05) positions.
There were significant negative linear correlations between stiffness with distance from the calcar on anteroposterior radiographs and load-to-failure with distance from the center of femoral neck on the lateral radiographs.

Conclusions

The inferior lag screw position produced the highest axial and torsional stiffness. Anterior and posterior lag screw positions produced the lowest stiffnesses and load-to-failure. Inferior placement of the lag screw on the anteroposterior radiograph and central placement on the lateral radiographs is recommended.

Supplemental

Femoral Head Lag Screw Position for Cephalomedullary Nails: A Biomechanical Analysis.

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Problems in the Management of Type III (Severe) Open Fractures: A New Classification of Type III Open Fractures.

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Neer Award 2005: The Grammont Reverse Shoulder Prosthesis: Results in Cuff Tear Arthritis, Fracture Sequelae, and Revision Arthroplasty.

Boileau, Hovorka, et al.J Shoulder Elbow Surg20061,115 citationsProspective cohort

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A System for the Surgical Staging of Musculoskeletal Sarcoma.

Enneking, Goodman, et al.Clin Orthop Relat Res19802,112 citationsRetrospective cohort

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Fracture Fixation in the Operative Management of Hip Fractures (FAITH): An International, Multicentre, Randomised Controlled Trial.

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Dislocations after Total Hip-Replacement Arthroplasties.

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Landmark

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PipkinJ Bone Joint Surg Am1957445 citationsCase series

Landmark

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Landmark

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Landmark

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Landmark

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Landmark

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Landmark

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Landmark

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Femoral Head Lag Screw Position for Cephalomedullary Nails: A Biomechanical Analysis

Kuzyk, Schemitsch, et al.·J Orthop Trauma·2012·160 citations·Biomechanical study

DOI·PubMed

Purpose

The purpose of this study was to determine if lag screw position affects the biomechanical properties of a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Methods

Unstable peritrochanteric fractures were created in 30 synthetic femurs and repaired with Long Gamma 3 Nails using one of 5 lag screw positions: superior, inferior, anterior, posterior, or central.
Radiographic measurements including tip-apex distance and a calcar referenced tip-apex distance were calculated from anteroposterior and lateral radiographs.
Specimens were tested for axial, lateral bending, and torsional stiffness and then loaded to failure in the axial position.
Analysis of variance and linear regression were used for statistical analysis.

Results

The inferior lag screw position had significantly greater mean axial stiffness than superior (P < 0.01), anterior (P = 0.02), and posterior (P = 0.04) positions.
Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared with other lag screw positions (P < 0.01 all 4 pairings).
No statistical differences were noted for lateral bending stiffness.
Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (P < 0.01 and P = 0.02) and posterior (P < 0.01 and P = 0.05) positions.
There were significant negative linear correlations between stiffness with distance from the calcar on anteroposterior radiographs and load-to-failure with distance from the center of femoral neck on the lateral radiographs.

Conclusions

Purpose

The purpose of this study was to determine if lag screw position affects the biomechanical properties of a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Methods

Unstable peritrochanteric fractures were created in 30 synthetic femurs and repaired with Long Gamma 3 Nails using one of 5 lag screw positions: superior, inferior, anterior, posterior, or central.
Radiographic measurements including tip-apex distance and a calcar referenced tip-apex distance were calculated from anteroposterior and lateral radiographs.
Specimens were tested for axial, lateral bending, and torsional stiffness and then loaded to failure in the axial position.
Analysis of variance and linear regression were used for statistical analysis.

Results

The inferior lag screw position had significantly greater mean axial stiffness than superior (P < 0.01), anterior (P = 0.02), and posterior (P = 0.04) positions.
Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared with other lag screw positions (P < 0.01 all 4 pairings).
No statistical differences were noted for lateral bending stiffness.
Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (P < 0.01 and P = 0.02) and posterior (P < 0.01 and P = 0.05) positions.
There were significant negative linear correlations between stiffness with distance from the calcar on anteroposterior radiographs and load-to-failure with distance from the center of femoral neck on the lateral radiographs.

Conclusions

Purpose

The purpose of this study was to determine if lag screw position affects the biomechanical properties of a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Methods

Unstable peritrochanteric fractures were created in 30 synthetic femurs and repaired with Long Gamma 3 Nails using one of 5 lag screw positions: superior, inferior, anterior, posterior, or central.
Radiographic measurements including tip-apex distance and a calcar referenced tip-apex distance were calculated from anteroposterior and lateral radiographs.
Specimens were tested for axial, lateral bending, and torsional stiffness and then loaded to failure in the axial position.
Analysis of variance and linear regression were used for statistical analysis.

Results

The inferior lag screw position had significantly greater mean axial stiffness than superior (P < 0.01), anterior (P = 0.02), and posterior (P = 0.04) positions.
Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared with other lag screw positions (P < 0.01 all 4 pairings).
No statistical differences were noted for lateral bending stiffness.
Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (P < 0.01 and P = 0.02) and posterior (P < 0.01 and P = 0.05) positions.
There were significant negative linear correlations between stiffness with distance from the calcar on anteroposterior radiographs and load-to-failure with distance from the center of femoral neck on the lateral radiographs.