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Marion Rapp - One of the best experts on this subject based on the ideXlab platform.

  • additional tension screws improve stability in elastic stable intramedullary nailing biomechanical analysis of a femur Spiral Fracture model
    European Journal of Pediatric Surgery, 2014
    Co-Authors: Gregor Zachert, Marion Rapp, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Martin M Kaiser
    Abstract:

    PURPOSE For pediatric femoral shaft Fractures, elastic stable intramedullary nailing (ESIN) is an accepted method of treatment. But problems regarding stability with shortening or axial deviation are well known in complex Fracture types and heavier children. Biomechanical in vitro testing was performed to determine whether two modified osteosyntheses with an additional tension screw fixation or screw fixation alone without nails could significantly improve the stability in comparison to classical ESIN. METHODS A total of 24 synthetic adolescent-sized femoral bone models (Sawbones, 4th generation; Vashon, Washington, United States) with an identical Spiral Fracture (length 100 mm) were used. All grafts underwent retrograde fixation with two C-shaped steel nails (2C). Of the 24, 8 osteosyntheses were supported by one additional tension screw (2C1S) and another 8 by two screws (2S) in which the intramedullary nails were removed before testing. Each configuration underwent biomechanical testing in 4-point bending, external rotation (ER) and internal rotation (IR). Furthermore, the modifications were tested in axial physiological 9 degrees position for shifting and dynamic compression as well as dynamic load. RESULTS Both screw configurations (2C1S and 2S) demonstrated a significantly higher stability in comparison to the 2C configuration in 4-point bending (anterior-posterior, 0.95 Nm/mm [2C] < 8.41 Nm/mm [2C1S] and 15.12 Nm/mm [2S]; posterior-anterior, 8.55 Nm/mm [2C] < 12.65 Nm/mm [2C1S] and 17.54 Nm/mm [2S]; latero-medial, 1.17 Nm/mm [2C] < 5.53 Nm/mm [2C1S] and 9.15 Nm/mm [2S]; medio-lateral, 1.74 Nm/mm [2C] < 9.69 Nm/mm [2C1S] and 12.20 Nm [2S]; all p < 0.001) and during torsion (ER, 0.61 Nm/degree [2C] < 4.10 Nm/degree [2C1S] and 9.29 Nm/degree [2S]; IR, 0.18 Nm/degree [2C] < 6.17 Nm/degree [2C1S] and 10.61 Nm/degree [2S]; all p < 0.001]. The shifting in compression in 9 degrees position was only slightly influenced. The comparison of 2S versus 2C1S showed more stability for 2S than 2C1S in all testing, except the axial 9 degrees compression tests for shifting. In contrast to the 2C configuration, both modifications (2C1S and 2S) turned out to be stable in dynamic 9 degrees axial compression with a force of 100 up to 1,000 N at 2.5 Hz in 250,000 load cycles. CONCLUSIONS In this in vitro adolescence femur Spiral Fracture model, the stability of ESIN could be significantly improved by two modifications with additional tension screws. If transferred in clinical practice, these modifications might offer earlier weight bearing and less problems of shortening or axial deviation.

  • modification of elastic stable intramedullary nailing with a 3rd nail in a femoral Spiral Fracture model results of biomechanical testing and a prospective clinical study
    BMC Musculoskeletal Disorders, 2014
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christine Stratmann, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral Fractures in children. However, high complication rates (10-50%) are reported in complex Fractures. This biomechanical study compares the stiffness with a 3rd nail implanted to that in the classical 2C-shaped configuration and presents the application into clinical practice. For each of the 3 configurations of ESIN-osteosynthesis with titanium nails eight composite femoral grafts (Sawbones®) with an identical Spiral Fracture were used: 2C configuration (2C-shaped nails, 2 × 3.5 mm), 3CM configuration (3rd nail from medial) and 3CL configuration (3rd nail from lateral). Each group underwent biomechanical testing in 4-point bending, internal/external rotation and axial compression. 2C and 3CM configurations showed no significant differences in this spiroid type Fracture model. 3CL had a significantly higher stiffness during anterior-posterior bending, internal rotation and 9° compression than 2C, and was stiffer in the lateral-medial direction than 3CM. The 3CL was less stable during p-a bending and external rotation than both the others. As biomechanical testing showed a higher stability for the 3CL configuration in two (a-p corresponding to recurvation and 9° compression to shortening) of three directions associated with the most important clinical problems, we added a 3rd nail in ESIN-osteosynthesis for femoral Fractures. 11 boys and 6 girls (2.5-15 years) were treated with modified ESIN of whom 12 were ‘3CL’; due to the individual character of the Fractures 4 patients were treated with ‘3CM’ (third nail from medial) and as an exception 1 adolescent with 4 nails and one boy with plate osteosynthesis. No additional stabilizations or re-operations were necessary. All patients achieved full points in the Harris-Score at follow-up; no limb length discrepancy occurred. The 3CL configuration provided a significantly higher stiffness than 2C and 3CM configurations in this biomechanical model. These results were successfully transmitted into clinical practice. All children, treated by 3CL or 3CM according to the individual character of each Fracture, needed no additional stabilization and had no Re-Do operations. As a consequence, at our hospital all children with femoral diaphyseal Fractures with open physis are treated with this modified ESIN-technique.

  • increasing stability by pre bending the nails in elastic stable intramedullary nailing a biomechanical analysis of a synthetic femoral Spiral Fracture model
    Journal of Bone and Joint Surgery-british Volume, 2012
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral Fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated Fracture, we performed biomechanical testing to determine the influence on the stability of the Fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a Spiral Fracture. In eight cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the Fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in Spiral Fractures and reduce the complications of varus deformity and shortening.

  • biomechanical analysis of a synthetic femoral Spiral Fracture model do end caps improve retrograde flexible intramedullary nail fixation
    Journal of Orthopaedic Surgery and Research, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Marion Rapp, Rebecca Eggert, Robert Wendlandt, Christine Stratmann, Lucas Wessel, Arndt P Schulz, Benjamin Kienast
    Abstract:

    Elastic Stable intramedullary Nailing (ESIN) of dislocated diaphyseal femur Fractures has become an accepted method for the treatment in children and adolescents with open physis. Studies focused on complications of this technique showed problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. Biomechanical in vitro testing was performed to evaluate the stability of simulated Spiral femoral Fractures after retrograde flexible titanium intramedullary nail fixation with and without End caps. Eight synthetic adolescent-size femoral bone models (Sawbones® with a medullar canal of 10 mm and a Spiral Fracture of 100 mm length identically sawn by the manufacturer) were used for each group. Both groups underwent retrograde fixation with two 3.5 mm Titanium C-shaped nails inserted from medial and lateral entry portals. In the End Cap group the ends of the nails of the eight specimens were covered with End Caps (Synthes Company, Oberdorf, Switzerland) at the distal entry. Beside posterior-anterior stress (4.11 Nm/mm vs. 1.78 Nm/mm, p < 0.001), the use of End Caps demonstrated no higher stability in 4-point bending compared to the group without End Caps (anterior-posterior bending 0.27 Nm/mm vs. 0.77 Nm/mm, p < 0.001; medial-lateral bending 0.8 Nm/mm vs. 1.10 Nm/mm, p < 0.01; lateral-medial bending 0.53 Nm/mm vs. 0.86 Nm/mm, p < 0.001) as well as during internal rotation (0.11 Nm/° vs. 0.14 Nm/°, p < 0.05). During compression in 9°- position and external rotation there was no statistical significant difference (0.37 Nm/° vs. 0.32 Nm/°, p = 0.13 and 1.29 mm vs. 2.18 mm, p = 0.20, respectively) compared to the "classic" 2-C-shaped osteosynthesis without End Caps. In this biomechanical study the use of End Caps did not improve the stability of the intramedullary flexible nail osteosynthesis.

  • biomechanical analysis of a synthetic femur Spiral Fracture model influence of different materials on the stiffness in flexible intramedullary nailing
    Clinical Biomechanics, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Lucas Wessel, Benjamin Kienast, Marion Rapp
    Abstract:

    Abstract Background Flexible intramedullary nail fixation of dislocated diaphyseal femur Fractures has gained wide acceptance for children and adolescents with open physes. Studies with a special emphasis on complications reveal frequent problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. This biomechanical study analyses how much the material of the nails influences the stiffness in a synthetic bone model. Methods Twenty-four composite grafts (Sawbones®, 4th generation, medullar canal of 10 mm) with an identical Spiral Fracture were used in three configurations of eight grafts. Elastic stable intramedullary nailing was performed in a retrograde C-shaped manner with two nails of equal size (2 × 3.5 mm). Close contact of the fragments could be achieved. We compared Group A (steel nails) with Group B and C (two types of titanium nails). All specimens underwent 4-point bending, torsion and axial compression in the 0° and 9° positions, and the results were analysed. Findings Group A (steel nails) revealed a significantly higher stiffness in all directions than Group B. Apart from compression in the 9° position this steel nail fixation showed significant higher stiffness than titanium nails of Group C. Comparing Group B and C did not show an systematic difference. Interpretation In this biomechanical study with composite artificial bones the use of steel Nails demonstrated the highest stiffness in our model when compared to two different titanium nail configurations. Apart from in cases of known allergy or planned MRI-examinations our results and data from the literature question the use of titanium nails.

Martin M Kaiser - One of the best experts on this subject based on the ideXlab platform.

  • additional tension screws improve stability in elastic stable intramedullary nailing biomechanical analysis of a femur Spiral Fracture model
    European Journal of Pediatric Surgery, 2014
    Co-Authors: Gregor Zachert, Marion Rapp, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Martin M Kaiser
    Abstract:

    PURPOSE For pediatric femoral shaft Fractures, elastic stable intramedullary nailing (ESIN) is an accepted method of treatment. But problems regarding stability with shortening or axial deviation are well known in complex Fracture types and heavier children. Biomechanical in vitro testing was performed to determine whether two modified osteosyntheses with an additional tension screw fixation or screw fixation alone without nails could significantly improve the stability in comparison to classical ESIN. METHODS A total of 24 synthetic adolescent-sized femoral bone models (Sawbones, 4th generation; Vashon, Washington, United States) with an identical Spiral Fracture (length 100 mm) were used. All grafts underwent retrograde fixation with two C-shaped steel nails (2C). Of the 24, 8 osteosyntheses were supported by one additional tension screw (2C1S) and another 8 by two screws (2S) in which the intramedullary nails were removed before testing. Each configuration underwent biomechanical testing in 4-point bending, external rotation (ER) and internal rotation (IR). Furthermore, the modifications were tested in axial physiological 9 degrees position for shifting and dynamic compression as well as dynamic load. RESULTS Both screw configurations (2C1S and 2S) demonstrated a significantly higher stability in comparison to the 2C configuration in 4-point bending (anterior-posterior, 0.95 Nm/mm [2C] < 8.41 Nm/mm [2C1S] and 15.12 Nm/mm [2S]; posterior-anterior, 8.55 Nm/mm [2C] < 12.65 Nm/mm [2C1S] and 17.54 Nm/mm [2S]; latero-medial, 1.17 Nm/mm [2C] < 5.53 Nm/mm [2C1S] and 9.15 Nm/mm [2S]; medio-lateral, 1.74 Nm/mm [2C] < 9.69 Nm/mm [2C1S] and 12.20 Nm [2S]; all p < 0.001) and during torsion (ER, 0.61 Nm/degree [2C] < 4.10 Nm/degree [2C1S] and 9.29 Nm/degree [2S]; IR, 0.18 Nm/degree [2C] < 6.17 Nm/degree [2C1S] and 10.61 Nm/degree [2S]; all p < 0.001]. The shifting in compression in 9 degrees position was only slightly influenced. The comparison of 2S versus 2C1S showed more stability for 2S than 2C1S in all testing, except the axial 9 degrees compression tests for shifting. In contrast to the 2C configuration, both modifications (2C1S and 2S) turned out to be stable in dynamic 9 degrees axial compression with a force of 100 up to 1,000 N at 2.5 Hz in 250,000 load cycles. CONCLUSIONS In this in vitro adolescence femur Spiral Fracture model, the stability of ESIN could be significantly improved by two modifications with additional tension screws. If transferred in clinical practice, these modifications might offer earlier weight bearing and less problems of shortening or axial deviation.

  • modification of elastic stable intramedullary nailing with a 3rd nail in a femoral Spiral Fracture model results of biomechanical testing and a prospective clinical study
    BMC Musculoskeletal Disorders, 2014
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christine Stratmann, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral Fractures in children. However, high complication rates (10-50%) are reported in complex Fractures. This biomechanical study compares the stiffness with a 3rd nail implanted to that in the classical 2C-shaped configuration and presents the application into clinical practice. For each of the 3 configurations of ESIN-osteosynthesis with titanium nails eight composite femoral grafts (Sawbones®) with an identical Spiral Fracture were used: 2C configuration (2C-shaped nails, 2 × 3.5 mm), 3CM configuration (3rd nail from medial) and 3CL configuration (3rd nail from lateral). Each group underwent biomechanical testing in 4-point bending, internal/external rotation and axial compression. 2C and 3CM configurations showed no significant differences in this spiroid type Fracture model. 3CL had a significantly higher stiffness during anterior-posterior bending, internal rotation and 9° compression than 2C, and was stiffer in the lateral-medial direction than 3CM. The 3CL was less stable during p-a bending and external rotation than both the others. As biomechanical testing showed a higher stability for the 3CL configuration in two (a-p corresponding to recurvation and 9° compression to shortening) of three directions associated with the most important clinical problems, we added a 3rd nail in ESIN-osteosynthesis for femoral Fractures. 11 boys and 6 girls (2.5-15 years) were treated with modified ESIN of whom 12 were ‘3CL’; due to the individual character of the Fractures 4 patients were treated with ‘3CM’ (third nail from medial) and as an exception 1 adolescent with 4 nails and one boy with plate osteosynthesis. No additional stabilizations or re-operations were necessary. All patients achieved full points in the Harris-Score at follow-up; no limb length discrepancy occurred. The 3CL configuration provided a significantly higher stiffness than 2C and 3CM configurations in this biomechanical model. These results were successfully transmitted into clinical practice. All children, treated by 3CL or 3CM according to the individual character of each Fracture, needed no additional stabilization and had no Re-Do operations. As a consequence, at our hospital all children with femoral diaphyseal Fractures with open physis are treated with this modified ESIN-technique.

  • increasing stability by pre bending the nails in elastic stable intramedullary nailing a biomechanical analysis of a synthetic femoral Spiral Fracture model
    Journal of Bone and Joint Surgery-british Volume, 2012
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral Fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated Fracture, we performed biomechanical testing to determine the influence on the stability of the Fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a Spiral Fracture. In eight cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the Fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in Spiral Fractures and reduce the complications of varus deformity and shortening.

  • biomechanical analysis of a synthetic femoral Spiral Fracture model do end caps improve retrograde flexible intramedullary nail fixation
    Journal of Orthopaedic Surgery and Research, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Marion Rapp, Rebecca Eggert, Robert Wendlandt, Christine Stratmann, Lucas Wessel, Arndt P Schulz, Benjamin Kienast
    Abstract:

    Elastic Stable intramedullary Nailing (ESIN) of dislocated diaphyseal femur Fractures has become an accepted method for the treatment in children and adolescents with open physis. Studies focused on complications of this technique showed problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. Biomechanical in vitro testing was performed to evaluate the stability of simulated Spiral femoral Fractures after retrograde flexible titanium intramedullary nail fixation with and without End caps. Eight synthetic adolescent-size femoral bone models (Sawbones® with a medullar canal of 10 mm and a Spiral Fracture of 100 mm length identically sawn by the manufacturer) were used for each group. Both groups underwent retrograde fixation with two 3.5 mm Titanium C-shaped nails inserted from medial and lateral entry portals. In the End Cap group the ends of the nails of the eight specimens were covered with End Caps (Synthes Company, Oberdorf, Switzerland) at the distal entry. Beside posterior-anterior stress (4.11 Nm/mm vs. 1.78 Nm/mm, p < 0.001), the use of End Caps demonstrated no higher stability in 4-point bending compared to the group without End Caps (anterior-posterior bending 0.27 Nm/mm vs. 0.77 Nm/mm, p < 0.001; medial-lateral bending 0.8 Nm/mm vs. 1.10 Nm/mm, p < 0.01; lateral-medial bending 0.53 Nm/mm vs. 0.86 Nm/mm, p < 0.001) as well as during internal rotation (0.11 Nm/° vs. 0.14 Nm/°, p < 0.05). During compression in 9°- position and external rotation there was no statistical significant difference (0.37 Nm/° vs. 0.32 Nm/°, p = 0.13 and 1.29 mm vs. 2.18 mm, p = 0.20, respectively) compared to the "classic" 2-C-shaped osteosynthesis without End Caps. In this biomechanical study the use of End Caps did not improve the stability of the intramedullary flexible nail osteosynthesis.

  • biomechanical analysis of a synthetic femur Spiral Fracture model influence of different materials on the stiffness in flexible intramedullary nailing
    Clinical Biomechanics, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Lucas Wessel, Benjamin Kienast, Marion Rapp
    Abstract:

    Abstract Background Flexible intramedullary nail fixation of dislocated diaphyseal femur Fractures has gained wide acceptance for children and adolescents with open physes. Studies with a special emphasis on complications reveal frequent problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. This biomechanical study analyses how much the material of the nails influences the stiffness in a synthetic bone model. Methods Twenty-four composite grafts (Sawbones®, 4th generation, medullar canal of 10 mm) with an identical Spiral Fracture were used in three configurations of eight grafts. Elastic stable intramedullary nailing was performed in a retrograde C-shaped manner with two nails of equal size (2 × 3.5 mm). Close contact of the fragments could be achieved. We compared Group A (steel nails) with Group B and C (two types of titanium nails). All specimens underwent 4-point bending, torsion and axial compression in the 0° and 9° positions, and the results were analysed. Findings Group A (steel nails) revealed a significantly higher stiffness in all directions than Group B. Apart from compression in the 9° position this steel nail fixation showed significant higher stiffness than titanium nails of Group C. Comparing Group B and C did not show an systematic difference. Interpretation In this biomechanical study with composite artificial bones the use of steel Nails demonstrated the highest stiffness in our model when compared to two different titanium nail configurations. Apart from in cases of known allergy or planned MRI-examinations our results and data from the literature question the use of titanium nails.

Gregor Zachert - One of the best experts on this subject based on the ideXlab platform.

  • additional tension screws improve stability in elastic stable intramedullary nailing biomechanical analysis of a femur Spiral Fracture model
    European Journal of Pediatric Surgery, 2014
    Co-Authors: Gregor Zachert, Marion Rapp, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Martin M Kaiser
    Abstract:

    PURPOSE For pediatric femoral shaft Fractures, elastic stable intramedullary nailing (ESIN) is an accepted method of treatment. But problems regarding stability with shortening or axial deviation are well known in complex Fracture types and heavier children. Biomechanical in vitro testing was performed to determine whether two modified osteosyntheses with an additional tension screw fixation or screw fixation alone without nails could significantly improve the stability in comparison to classical ESIN. METHODS A total of 24 synthetic adolescent-sized femoral bone models (Sawbones, 4th generation; Vashon, Washington, United States) with an identical Spiral Fracture (length 100 mm) were used. All grafts underwent retrograde fixation with two C-shaped steel nails (2C). Of the 24, 8 osteosyntheses were supported by one additional tension screw (2C1S) and another 8 by two screws (2S) in which the intramedullary nails were removed before testing. Each configuration underwent biomechanical testing in 4-point bending, external rotation (ER) and internal rotation (IR). Furthermore, the modifications were tested in axial physiological 9 degrees position for shifting and dynamic compression as well as dynamic load. RESULTS Both screw configurations (2C1S and 2S) demonstrated a significantly higher stability in comparison to the 2C configuration in 4-point bending (anterior-posterior, 0.95 Nm/mm [2C] < 8.41 Nm/mm [2C1S] and 15.12 Nm/mm [2S]; posterior-anterior, 8.55 Nm/mm [2C] < 12.65 Nm/mm [2C1S] and 17.54 Nm/mm [2S]; latero-medial, 1.17 Nm/mm [2C] < 5.53 Nm/mm [2C1S] and 9.15 Nm/mm [2S]; medio-lateral, 1.74 Nm/mm [2C] < 9.69 Nm/mm [2C1S] and 12.20 Nm [2S]; all p < 0.001) and during torsion (ER, 0.61 Nm/degree [2C] < 4.10 Nm/degree [2C1S] and 9.29 Nm/degree [2S]; IR, 0.18 Nm/degree [2C] < 6.17 Nm/degree [2C1S] and 10.61 Nm/degree [2S]; all p < 0.001]. The shifting in compression in 9 degrees position was only slightly influenced. The comparison of 2S versus 2C1S showed more stability for 2S than 2C1S in all testing, except the axial 9 degrees compression tests for shifting. In contrast to the 2C configuration, both modifications (2C1S and 2S) turned out to be stable in dynamic 9 degrees axial compression with a force of 100 up to 1,000 N at 2.5 Hz in 250,000 load cycles. CONCLUSIONS In this in vitro adolescence femur Spiral Fracture model, the stability of ESIN could be significantly improved by two modifications with additional tension screws. If transferred in clinical practice, these modifications might offer earlier weight bearing and less problems of shortening or axial deviation.

  • modification of elastic stable intramedullary nailing with a 3rd nail in a femoral Spiral Fracture model results of biomechanical testing and a prospective clinical study
    BMC Musculoskeletal Disorders, 2014
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christine Stratmann, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral Fractures in children. However, high complication rates (10-50%) are reported in complex Fractures. This biomechanical study compares the stiffness with a 3rd nail implanted to that in the classical 2C-shaped configuration and presents the application into clinical practice. For each of the 3 configurations of ESIN-osteosynthesis with titanium nails eight composite femoral grafts (Sawbones®) with an identical Spiral Fracture were used: 2C configuration (2C-shaped nails, 2 × 3.5 mm), 3CM configuration (3rd nail from medial) and 3CL configuration (3rd nail from lateral). Each group underwent biomechanical testing in 4-point bending, internal/external rotation and axial compression. 2C and 3CM configurations showed no significant differences in this spiroid type Fracture model. 3CL had a significantly higher stiffness during anterior-posterior bending, internal rotation and 9° compression than 2C, and was stiffer in the lateral-medial direction than 3CM. The 3CL was less stable during p-a bending and external rotation than both the others. As biomechanical testing showed a higher stability for the 3CL configuration in two (a-p corresponding to recurvation and 9° compression to shortening) of three directions associated with the most important clinical problems, we added a 3rd nail in ESIN-osteosynthesis for femoral Fractures. 11 boys and 6 girls (2.5-15 years) were treated with modified ESIN of whom 12 were ‘3CL’; due to the individual character of the Fractures 4 patients were treated with ‘3CM’ (third nail from medial) and as an exception 1 adolescent with 4 nails and one boy with plate osteosynthesis. No additional stabilizations or re-operations were necessary. All patients achieved full points in the Harris-Score at follow-up; no limb length discrepancy occurred. The 3CL configuration provided a significantly higher stiffness than 2C and 3CM configurations in this biomechanical model. These results were successfully transmitted into clinical practice. All children, treated by 3CL or 3CM according to the individual character of each Fracture, needed no additional stabilization and had no Re-Do operations. As a consequence, at our hospital all children with femoral diaphyseal Fractures with open physis are treated with this modified ESIN-technique.

  • increasing stability by pre bending the nails in elastic stable intramedullary nailing a biomechanical analysis of a synthetic femoral Spiral Fracture model
    Journal of Bone and Joint Surgery-british Volume, 2012
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral Fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated Fracture, we performed biomechanical testing to determine the influence on the stability of the Fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a Spiral Fracture. In eight cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the Fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in Spiral Fractures and reduce the complications of varus deformity and shortening.

  • biomechanical analysis of a synthetic femoral Spiral Fracture model do end caps improve retrograde flexible intramedullary nail fixation
    Journal of Orthopaedic Surgery and Research, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Marion Rapp, Rebecca Eggert, Robert Wendlandt, Christine Stratmann, Lucas Wessel, Arndt P Schulz, Benjamin Kienast
    Abstract:

    Elastic Stable intramedullary Nailing (ESIN) of dislocated diaphyseal femur Fractures has become an accepted method for the treatment in children and adolescents with open physis. Studies focused on complications of this technique showed problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. Biomechanical in vitro testing was performed to evaluate the stability of simulated Spiral femoral Fractures after retrograde flexible titanium intramedullary nail fixation with and without End caps. Eight synthetic adolescent-size femoral bone models (Sawbones® with a medullar canal of 10 mm and a Spiral Fracture of 100 mm length identically sawn by the manufacturer) were used for each group. Both groups underwent retrograde fixation with two 3.5 mm Titanium C-shaped nails inserted from medial and lateral entry portals. In the End Cap group the ends of the nails of the eight specimens were covered with End Caps (Synthes Company, Oberdorf, Switzerland) at the distal entry. Beside posterior-anterior stress (4.11 Nm/mm vs. 1.78 Nm/mm, p < 0.001), the use of End Caps demonstrated no higher stability in 4-point bending compared to the group without End Caps (anterior-posterior bending 0.27 Nm/mm vs. 0.77 Nm/mm, p < 0.001; medial-lateral bending 0.8 Nm/mm vs. 1.10 Nm/mm, p < 0.01; lateral-medial bending 0.53 Nm/mm vs. 0.86 Nm/mm, p < 0.001) as well as during internal rotation (0.11 Nm/° vs. 0.14 Nm/°, p < 0.05). During compression in 9°- position and external rotation there was no statistical significant difference (0.37 Nm/° vs. 0.32 Nm/°, p = 0.13 and 1.29 mm vs. 2.18 mm, p = 0.20, respectively) compared to the "classic" 2-C-shaped osteosynthesis without End Caps. In this biomechanical study the use of End Caps did not improve the stability of the intramedullary flexible nail osteosynthesis.

  • biomechanical analysis of a synthetic femur Spiral Fracture model influence of different materials on the stiffness in flexible intramedullary nailing
    Clinical Biomechanics, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Lucas Wessel, Benjamin Kienast, Marion Rapp
    Abstract:

    Abstract Background Flexible intramedullary nail fixation of dislocated diaphyseal femur Fractures has gained wide acceptance for children and adolescents with open physes. Studies with a special emphasis on complications reveal frequent problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. This biomechanical study analyses how much the material of the nails influences the stiffness in a synthetic bone model. Methods Twenty-four composite grafts (Sawbones®, 4th generation, medullar canal of 10 mm) with an identical Spiral Fracture were used in three configurations of eight grafts. Elastic stable intramedullary nailing was performed in a retrograde C-shaped manner with two nails of equal size (2 × 3.5 mm). Close contact of the fragments could be achieved. We compared Group A (steel nails) with Group B and C (two types of titanium nails). All specimens underwent 4-point bending, torsion and axial compression in the 0° and 9° positions, and the results were analysed. Findings Group A (steel nails) revealed a significantly higher stiffness in all directions than Group B. Apart from compression in the 9° position this steel nail fixation showed significant higher stiffness than titanium nails of Group C. Comparing Group B and C did not show an systematic difference. Interpretation In this biomechanical study with composite artificial bones the use of steel Nails demonstrated the highest stiffness in our model when compared to two different titanium nail configurations. Apart from in cases of known allergy or planned MRI-examinations our results and data from the literature question the use of titanium nails.

Rebecca Eggert - One of the best experts on this subject based on the ideXlab platform.

  • additional tension screws improve stability in elastic stable intramedullary nailing biomechanical analysis of a femur Spiral Fracture model
    European Journal of Pediatric Surgery, 2014
    Co-Authors: Gregor Zachert, Marion Rapp, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Martin M Kaiser
    Abstract:

    PURPOSE For pediatric femoral shaft Fractures, elastic stable intramedullary nailing (ESIN) is an accepted method of treatment. But problems regarding stability with shortening or axial deviation are well known in complex Fracture types and heavier children. Biomechanical in vitro testing was performed to determine whether two modified osteosyntheses with an additional tension screw fixation or screw fixation alone without nails could significantly improve the stability in comparison to classical ESIN. METHODS A total of 24 synthetic adolescent-sized femoral bone models (Sawbones, 4th generation; Vashon, Washington, United States) with an identical Spiral Fracture (length 100 mm) were used. All grafts underwent retrograde fixation with two C-shaped steel nails (2C). Of the 24, 8 osteosyntheses were supported by one additional tension screw (2C1S) and another 8 by two screws (2S) in which the intramedullary nails were removed before testing. Each configuration underwent biomechanical testing in 4-point bending, external rotation (ER) and internal rotation (IR). Furthermore, the modifications were tested in axial physiological 9 degrees position for shifting and dynamic compression as well as dynamic load. RESULTS Both screw configurations (2C1S and 2S) demonstrated a significantly higher stability in comparison to the 2C configuration in 4-point bending (anterior-posterior, 0.95 Nm/mm [2C] < 8.41 Nm/mm [2C1S] and 15.12 Nm/mm [2S]; posterior-anterior, 8.55 Nm/mm [2C] < 12.65 Nm/mm [2C1S] and 17.54 Nm/mm [2S]; latero-medial, 1.17 Nm/mm [2C] < 5.53 Nm/mm [2C1S] and 9.15 Nm/mm [2S]; medio-lateral, 1.74 Nm/mm [2C] < 9.69 Nm/mm [2C1S] and 12.20 Nm [2S]; all p < 0.001) and during torsion (ER, 0.61 Nm/degree [2C] < 4.10 Nm/degree [2C1S] and 9.29 Nm/degree [2S]; IR, 0.18 Nm/degree [2C] < 6.17 Nm/degree [2C1S] and 10.61 Nm/degree [2S]; all p < 0.001]. The shifting in compression in 9 degrees position was only slightly influenced. The comparison of 2S versus 2C1S showed more stability for 2S than 2C1S in all testing, except the axial 9 degrees compression tests for shifting. In contrast to the 2C configuration, both modifications (2C1S and 2S) turned out to be stable in dynamic 9 degrees axial compression with a force of 100 up to 1,000 N at 2.5 Hz in 250,000 load cycles. CONCLUSIONS In this in vitro adolescence femur Spiral Fracture model, the stability of ESIN could be significantly improved by two modifications with additional tension screws. If transferred in clinical practice, these modifications might offer earlier weight bearing and less problems of shortening or axial deviation.

  • modification of elastic stable intramedullary nailing with a 3rd nail in a femoral Spiral Fracture model results of biomechanical testing and a prospective clinical study
    BMC Musculoskeletal Disorders, 2014
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christine Stratmann, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral Fractures in children. However, high complication rates (10-50%) are reported in complex Fractures. This biomechanical study compares the stiffness with a 3rd nail implanted to that in the classical 2C-shaped configuration and presents the application into clinical practice. For each of the 3 configurations of ESIN-osteosynthesis with titanium nails eight composite femoral grafts (Sawbones®) with an identical Spiral Fracture were used: 2C configuration (2C-shaped nails, 2 × 3.5 mm), 3CM configuration (3rd nail from medial) and 3CL configuration (3rd nail from lateral). Each group underwent biomechanical testing in 4-point bending, internal/external rotation and axial compression. 2C and 3CM configurations showed no significant differences in this spiroid type Fracture model. 3CL had a significantly higher stiffness during anterior-posterior bending, internal rotation and 9° compression than 2C, and was stiffer in the lateral-medial direction than 3CM. The 3CL was less stable during p-a bending and external rotation than both the others. As biomechanical testing showed a higher stability for the 3CL configuration in two (a-p corresponding to recurvation and 9° compression to shortening) of three directions associated with the most important clinical problems, we added a 3rd nail in ESIN-osteosynthesis for femoral Fractures. 11 boys and 6 girls (2.5-15 years) were treated with modified ESIN of whom 12 were ‘3CL’; due to the individual character of the Fractures 4 patients were treated with ‘3CM’ (third nail from medial) and as an exception 1 adolescent with 4 nails and one boy with plate osteosynthesis. No additional stabilizations or re-operations were necessary. All patients achieved full points in the Harris-Score at follow-up; no limb length discrepancy occurred. The 3CL configuration provided a significantly higher stiffness than 2C and 3CM configurations in this biomechanical model. These results were successfully transmitted into clinical practice. All children, treated by 3CL or 3CM according to the individual character of each Fracture, needed no additional stabilization and had no Re-Do operations. As a consequence, at our hospital all children with femoral diaphyseal Fractures with open physis are treated with this modified ESIN-technique.

  • increasing stability by pre bending the nails in elastic stable intramedullary nailing a biomechanical analysis of a synthetic femoral Spiral Fracture model
    Journal of Bone and Joint Surgery-british Volume, 2012
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral Fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated Fracture, we performed biomechanical testing to determine the influence on the stability of the Fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a Spiral Fracture. In eight cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the Fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in Spiral Fractures and reduce the complications of varus deformity and shortening.

  • biomechanical analysis of a synthetic femoral Spiral Fracture model do end caps improve retrograde flexible intramedullary nail fixation
    Journal of Orthopaedic Surgery and Research, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Marion Rapp, Rebecca Eggert, Robert Wendlandt, Christine Stratmann, Lucas Wessel, Arndt P Schulz, Benjamin Kienast
    Abstract:

    Elastic Stable intramedullary Nailing (ESIN) of dislocated diaphyseal femur Fractures has become an accepted method for the treatment in children and adolescents with open physis. Studies focused on complications of this technique showed problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. Biomechanical in vitro testing was performed to evaluate the stability of simulated Spiral femoral Fractures after retrograde flexible titanium intramedullary nail fixation with and without End caps. Eight synthetic adolescent-size femoral bone models (Sawbones® with a medullar canal of 10 mm and a Spiral Fracture of 100 mm length identically sawn by the manufacturer) were used for each group. Both groups underwent retrograde fixation with two 3.5 mm Titanium C-shaped nails inserted from medial and lateral entry portals. In the End Cap group the ends of the nails of the eight specimens were covered with End Caps (Synthes Company, Oberdorf, Switzerland) at the distal entry. Beside posterior-anterior stress (4.11 Nm/mm vs. 1.78 Nm/mm, p < 0.001), the use of End Caps demonstrated no higher stability in 4-point bending compared to the group without End Caps (anterior-posterior bending 0.27 Nm/mm vs. 0.77 Nm/mm, p < 0.001; medial-lateral bending 0.8 Nm/mm vs. 1.10 Nm/mm, p < 0.01; lateral-medial bending 0.53 Nm/mm vs. 0.86 Nm/mm, p < 0.001) as well as during internal rotation (0.11 Nm/° vs. 0.14 Nm/°, p < 0.05). During compression in 9°- position and external rotation there was no statistical significant difference (0.37 Nm/° vs. 0.32 Nm/°, p = 0.13 and 1.29 mm vs. 2.18 mm, p = 0.20, respectively) compared to the "classic" 2-C-shaped osteosynthesis without End Caps. In this biomechanical study the use of End Caps did not improve the stability of the intramedullary flexible nail osteosynthesis.

  • biomechanical analysis of a synthetic femur Spiral Fracture model influence of different materials on the stiffness in flexible intramedullary nailing
    Clinical Biomechanics, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Lucas Wessel, Benjamin Kienast, Marion Rapp
    Abstract:

    Abstract Background Flexible intramedullary nail fixation of dislocated diaphyseal femur Fractures has gained wide acceptance for children and adolescents with open physes. Studies with a special emphasis on complications reveal frequent problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. This biomechanical study analyses how much the material of the nails influences the stiffness in a synthetic bone model. Methods Twenty-four composite grafts (Sawbones®, 4th generation, medullar canal of 10 mm) with an identical Spiral Fracture were used in three configurations of eight grafts. Elastic stable intramedullary nailing was performed in a retrograde C-shaped manner with two nails of equal size (2 × 3.5 mm). Close contact of the fragments could be achieved. We compared Group A (steel nails) with Group B and C (two types of titanium nails). All specimens underwent 4-point bending, torsion and axial compression in the 0° and 9° positions, and the results were analysed. Findings Group A (steel nails) revealed a significantly higher stiffness in all directions than Group B. Apart from compression in the 9° position this steel nail fixation showed significant higher stiffness than titanium nails of Group C. Comparing Group B and C did not show an systematic difference. Interpretation In this biomechanical study with composite artificial bones the use of steel Nails demonstrated the highest stiffness in our model when compared to two different titanium nail configurations. Apart from in cases of known allergy or planned MRI-examinations our results and data from the literature question the use of titanium nails.

Maaike Schulzehessing - One of the best experts on this subject based on the ideXlab platform.

  • additional tension screws improve stability in elastic stable intramedullary nailing biomechanical analysis of a femur Spiral Fracture model
    European Journal of Pediatric Surgery, 2014
    Co-Authors: Gregor Zachert, Marion Rapp, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Martin M Kaiser
    Abstract:

    PURPOSE For pediatric femoral shaft Fractures, elastic stable intramedullary nailing (ESIN) is an accepted method of treatment. But problems regarding stability with shortening or axial deviation are well known in complex Fracture types and heavier children. Biomechanical in vitro testing was performed to determine whether two modified osteosyntheses with an additional tension screw fixation or screw fixation alone without nails could significantly improve the stability in comparison to classical ESIN. METHODS A total of 24 synthetic adolescent-sized femoral bone models (Sawbones, 4th generation; Vashon, Washington, United States) with an identical Spiral Fracture (length 100 mm) were used. All grafts underwent retrograde fixation with two C-shaped steel nails (2C). Of the 24, 8 osteosyntheses were supported by one additional tension screw (2C1S) and another 8 by two screws (2S) in which the intramedullary nails were removed before testing. Each configuration underwent biomechanical testing in 4-point bending, external rotation (ER) and internal rotation (IR). Furthermore, the modifications were tested in axial physiological 9 degrees position for shifting and dynamic compression as well as dynamic load. RESULTS Both screw configurations (2C1S and 2S) demonstrated a significantly higher stability in comparison to the 2C configuration in 4-point bending (anterior-posterior, 0.95 Nm/mm [2C] < 8.41 Nm/mm [2C1S] and 15.12 Nm/mm [2S]; posterior-anterior, 8.55 Nm/mm [2C] < 12.65 Nm/mm [2C1S] and 17.54 Nm/mm [2S]; latero-medial, 1.17 Nm/mm [2C] < 5.53 Nm/mm [2C1S] and 9.15 Nm/mm [2S]; medio-lateral, 1.74 Nm/mm [2C] < 9.69 Nm/mm [2C1S] and 12.20 Nm [2S]; all p < 0.001) and during torsion (ER, 0.61 Nm/degree [2C] < 4.10 Nm/degree [2C1S] and 9.29 Nm/degree [2S]; IR, 0.18 Nm/degree [2C] < 6.17 Nm/degree [2C1S] and 10.61 Nm/degree [2S]; all p < 0.001]. The shifting in compression in 9 degrees position was only slightly influenced. The comparison of 2S versus 2C1S showed more stability for 2S than 2C1S in all testing, except the axial 9 degrees compression tests for shifting. In contrast to the 2C configuration, both modifications (2C1S and 2S) turned out to be stable in dynamic 9 degrees axial compression with a force of 100 up to 1,000 N at 2.5 Hz in 250,000 load cycles. CONCLUSIONS In this in vitro adolescence femur Spiral Fracture model, the stability of ESIN could be significantly improved by two modifications with additional tension screws. If transferred in clinical practice, these modifications might offer earlier weight bearing and less problems of shortening or axial deviation.

  • modification of elastic stable intramedullary nailing with a 3rd nail in a femoral Spiral Fracture model results of biomechanical testing and a prospective clinical study
    BMC Musculoskeletal Disorders, 2014
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christine Stratmann, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral Fractures in children. However, high complication rates (10-50%) are reported in complex Fractures. This biomechanical study compares the stiffness with a 3rd nail implanted to that in the classical 2C-shaped configuration and presents the application into clinical practice. For each of the 3 configurations of ESIN-osteosynthesis with titanium nails eight composite femoral grafts (Sawbones®) with an identical Spiral Fracture were used: 2C configuration (2C-shaped nails, 2 × 3.5 mm), 3CM configuration (3rd nail from medial) and 3CL configuration (3rd nail from lateral). Each group underwent biomechanical testing in 4-point bending, internal/external rotation and axial compression. 2C and 3CM configurations showed no significant differences in this spiroid type Fracture model. 3CL had a significantly higher stiffness during anterior-posterior bending, internal rotation and 9° compression than 2C, and was stiffer in the lateral-medial direction than 3CM. The 3CL was less stable during p-a bending and external rotation than both the others. As biomechanical testing showed a higher stability for the 3CL configuration in two (a-p corresponding to recurvation and 9° compression to shortening) of three directions associated with the most important clinical problems, we added a 3rd nail in ESIN-osteosynthesis for femoral Fractures. 11 boys and 6 girls (2.5-15 years) were treated with modified ESIN of whom 12 were ‘3CL’; due to the individual character of the Fractures 4 patients were treated with ‘3CM’ (third nail from medial) and as an exception 1 adolescent with 4 nails and one boy with plate osteosynthesis. No additional stabilizations or re-operations were necessary. All patients achieved full points in the Harris-Score at follow-up; no limb length discrepancy occurred. The 3CL configuration provided a significantly higher stiffness than 2C and 3CM configurations in this biomechanical model. These results were successfully transmitted into clinical practice. All children, treated by 3CL or 3CM according to the individual character of each Fracture, needed no additional stabilization and had no Re-Do operations. As a consequence, at our hospital all children with femoral diaphyseal Fractures with open physis are treated with this modified ESIN-technique.

  • increasing stability by pre bending the nails in elastic stable intramedullary nailing a biomechanical analysis of a synthetic femoral Spiral Fracture model
    Journal of Bone and Joint Surgery-british Volume, 2012
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Robert Wendlandt, Marion Rapp
    Abstract:

    Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral Fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated Fracture, we performed biomechanical testing to determine the influence on the stability of the Fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a Spiral Fracture. In eight cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the Fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in Spiral Fractures and reduce the complications of varus deformity and shortening.

  • biomechanical analysis of a synthetic femur Spiral Fracture model influence of different materials on the stiffness in flexible intramedullary nailing
    Clinical Biomechanics, 2011
    Co-Authors: Martin M Kaiser, Gregor Zachert, Rebecca Eggert, Maaike Schulzehessing, Nina Gros, Christina Stratmann, Lucas Wessel, Benjamin Kienast, Marion Rapp
    Abstract:

    Abstract Background Flexible intramedullary nail fixation of dislocated diaphyseal femur Fractures has gained wide acceptance for children and adolescents with open physes. Studies with a special emphasis on complications reveal frequent problems regarding stability, usually in complex Fracture types such as Spiral Fractures and in older children weighing > 40 kg. This biomechanical study analyses how much the material of the nails influences the stiffness in a synthetic bone model. Methods Twenty-four composite grafts (Sawbones®, 4th generation, medullar canal of 10 mm) with an identical Spiral Fracture were used in three configurations of eight grafts. Elastic stable intramedullary nailing was performed in a retrograde C-shaped manner with two nails of equal size (2 × 3.5 mm). Close contact of the fragments could be achieved. We compared Group A (steel nails) with Group B and C (two types of titanium nails). All specimens underwent 4-point bending, torsion and axial compression in the 0° and 9° positions, and the results were analysed. Findings Group A (steel nails) revealed a significantly higher stiffness in all directions than Group B. Apart from compression in the 9° position this steel nail fixation showed significant higher stiffness than titanium nails of Group C. Comparing Group B and C did not show an systematic difference. Interpretation In this biomechanical study with composite artificial bones the use of steel Nails demonstrated the highest stiffness in our model when compared to two different titanium nail configurations. Apart from in cases of known allergy or planned MRI-examinations our results and data from the literature question the use of titanium nails.