Radiographic Review of Helical Blade Versus Lag Screw Fixation for Cephalomedullary Nailing of Low-Energy Peritrochanteric Femur Fractures: There is a Difference in Cutout

Stern, Lorraine C.; Gorczyca, John T.; Kates, Stephen L.; Ketz, John; Soles, Gillian; Humphrey, Catherine A.

doi:10.1097/bot.0000000000000853

Cited by 53 publications

(61 citation statements)

References 20 publications

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“…We observed axial migration of the helical blade although the blade shaft was allowed to slide freely in the test fixture. Clinical series of intertrochanteric fractures demonstrated similar failure mechanisms as observed in our study . Deficient lateral buttress and unstable calcar patterns as mimicked by our test setup, have been described as additional factors for nail toggling and medial migration in intertrochanteric fractures …”

Section: Discussionsupporting

confidence: 83%

“…Helical blades exhibited axial migration with joint perforation in clinical series and revealed a higher cutout rate compared to other implant designs. 12,[24][25][26] A previous biomechanical study reported different direction of the migration vector of helical blades in comparison to dynamic hip screws. 4 We observed a nearly equidistant cranial/vertical and axial migration of helical blades in our test setup.…”

Section: Tip-apex Distance Of Helical Bladesmentioning

confidence: 99%

“…A TAD of less than 25 mm is recommended for helical blades to prevent varus tilt of the femoral head with subsequent cranial cutout. Attributed to the lower contact area of helical blades in axial direction compared to the sum of screw threads of conventional lag screws, helical blades exhibit a higher rate of axial migration with joint penetration …”

mentioning

confidence: 99%

“…11 In conventional screw designs as well as two screw designs predominantly cranial cutout with screw migration into the hip joint or beyond is observed. 12 To prevent cranial migration, a helical blade was introduced together with the proximal femur nail antirotation (PFNA) offering a larger contact area toward the cranial aspect of the surrounding bone and better rotational stability. 4 The helical blade exhibited a lower cranial cutout rate compared to conventional screw designs.…”

mentioning

confidence: 99%

“…Attributed to the lower contact area of helical blades in axial direction compared to the sum of screw threads of conventional lag screws, helical blades exhibit a higher rate of axial migration with joint penetration. 2,4,12 The effect of an increased TAD was extensively examined for conventional lag screws and helical blades, exhibiting a reduced stability of the lag screw anchorage and an earlier failure with cranial cutout. 9,14-17 However, the effect of a reduced TAD on the stability and failure rate of helical blades was never analyzed despite that it is considered as important parameter in view of axial migration.…”

mentioning

confidence: 99%

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Influence of reduced tip‐apex distance on helical blade fixation—a biomechanical study

Lenz

Schwinn

Hofmann‐Fliri

et al. 2019

Journal Orthopaedic Research

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Migration profile of helical blades differs from conventional screw design. Tip‐apex distance (TAD) greater than 25 mm is associated with early failure in hip screws. This study investigates the effect of a reduced TAD on helical blade fixation. Six pairs of human femoral heads were used. Bone mineral density (BMD) was determined by pQCT. Local bone quality was evaluated by breakaway torque. Helical blades were implanted with TAD of 20 mm (normal) and 6 mm (reduced). Specimens were cyclically tested under progressively increasing physiologic loading at 2 Hz with starting peak force of 1′000N, increasing by 0.1N/cycle. Implant migration was monitored by radiographs every 250 cycles. Paired Student's t‐test and Spearman rank correlation coefficient were used for statistical evaluation (p < 0.05). Mean BMD was 246.7 mgHA/cm3 SD48.7 (normal), 244.3 mgHA/cm3 SD47.6 (reduced); p = 0.93. Mean breakaway torque was 3.59 Nm SD2.11 (normal), 3.72 Nm SD1.83 (reduced); p = 0.91. Number of cycles to failure (1 mm vertical migration) was 16′416 SD7972 (normal), 20′000 SD5232 (reduced); p = 0.38. They correlated significantly with BMD (p = 0.01;R2 = 0.91) and breakaway torque (p < 0.049; R2 = 0.814) (normal). Breakaway torque correlated significantly with BMD (p = 0.02; R2 = 0.898) (normal). In reduced TAD these parameters did not correlate significantly. Normal TAD resulted in failure in varus collapse (n = 6), whereas reduced TAD showed blade perforation (n = 3), rotation (n = 2), varus collapse (n = 1). Fixation stability of helical blades correlates with bone quality when implants are fixed in cancellous bone. Near cortical blade fixation might increase the risk of intraarticular blade perforation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1–6, 2019.

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Section: Discussionsupporting

confidence: 83%