Biomechanical Evaluation of Threaded Headless .Headless Screws Compared to Traditional ... Biomechanical

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  • Biomechanical Evaluation of Threaded

    Headless Screws Compared to Traditional

    Headed Screws in Subtalar Fusion Model

    David E. Oji, Brent Parks, Mark Reed, Josh Nadaud, Michael Tsai, Alan Yan, Stuart Miller

    1

  • Biomechanical Evaluation of Threaded Headless

    Screws Compared to Traditional Headed Screws

    in Subtalar Fusion Model

    David Oji

    Stuart Miller

    My disclosure is in the

    Final AOFAS Program Book.

    I have no potential conflicts

    with this presentation

    2

  • Background:

    Headless screws shown to be equal or superior to traditional screws in: maintaining fixation in an osteotomy

    fracture reduction and fixation

    Headless screws provide a locking mechanism in the setting of lower compressive strength versus traditional screws

    Hypothesis: Headless screws hold a subtalar arthrodesis fusion model

    with less deformity in cyclic loading than conventional screws

    3

  • Method:

    12 matched pairs -> subtalar arthrodesis

    in-situ

    2 screw fixation of the subtalar joint

    1 extremity w/ Integra 7.5mm headless cannulated screws

    Contralateral side w/ AO 7.3mm partially threaded cannulated

    screws

    Joint surface was not prepared

    4

  • Method:

    Talus / calcaneus excised and mounted on loading frame

    Differential variable reluctance transducers used to measure motion

    Torque applied rate of 1 degree / sec

    0 N of axial load

    Stiffness and subtalar motion was assessed

    Paired t-test to determine statistical significance

    5

  • Results:

    Headless screws compared to traditional screws demonstrated less motion before and after cyclical loading to internal and external rotation (p

  • Results:

    Statistically significant higher initial stiffness to internal and external rotation (p

  • Discussion:

    Headless screws demonstrated statistically significant increased stiffness and less motion compared to traditional screws

    Possible improved biomechanical properties due to proximal locking mechanism

    Clinical application in fusions that require more stability or in patients with osteopenic bone

    Provide less soft tissue irritation

    Further studies are needed to determine the clinical significance of using headless screws in subtalar fusion

    8

  • Conclusion:

    The headless screw model was able to hold a

    subtalar arthrodesis with less deformity to cyclic

    loading compared to conventional headed

    screws

    9

  • References

    1. Abbasian A, Zaidi R, Guha A, Goldberg A, Cullen N, Singh D. Comparison of three different fixation methods of calcaneal osteotomies. Foot Ankle Int. 2013 Mar;34(3):420-5

    2. Somford MP, van Ooij B, Schafroth MU, Kloen P. Hoffa nonunion, two cases treated with headless compression screws. J Knee Surg. 2012 Jul 13

    3. Kokubu T, Nagura I, Mifune Y, Kurosaka M. Arthroscopic bony bankart repair using double-threaded headless screw: a case report. Case Rep Orthop. 2012

    4. Ball B, Bergman JW. Scaphoid excision and 4-corner fusion using retrograde headless compression screws. Tech Hand Up Extrem Surg. 2012 Dec;16(4):204-9

    5. Elkowitz SJ, Polatsch DB, Egol KA, Kummer FJ, Koval KJ. Capitellum fractures: a biomechanical evaluation of three fixation methods. . J Orthop Trauma. 2002 Aug;16(7):503-6

    6. Magee W, Hettwer W, Badra M, Bay B, Hart R. Biomechanical comparison of a fully threaded, variable pitch screw and a partially threaded lag screw for internal fixation of Type II dens fractures. Spine (Philadelphia, PA 1976). 2007 Aug 1;32(17):E475-9

    7. Capelle JH, Couch CG, Wells KM, Morris RP, Buford WL Jr, Merriman DJ, Panchbhavi VK. Fixation strength of anteriorly inserted headless screws for talar neck fractures. Foot Ankle Int. 2013 Mar 1

    8. Hintermann B, Valderrabano V, Nigg B. Influence of screw type on obtained contact area and contact force in a cadaveric subtalar arthrodesis model. Foot Ankle Int. 2002 Nov;23(11):986-91

    9. Sides SD, Fetter NL, Glisson R, Nunley JA. Bending stiffness and pull-out strength of tapered, variable pitch screws, and 6.5mm cancellous screws in acute Jones fractures. Foot Ankle Int. 2006 Oct;27(10):821-5

    10. Eddy AL, Galuppo LD, Stover SM, Taylor KT, Jensen DG. A biomechanical comparison of headless tapered variable pitch compression and AO cortical bone screws for fixation of a simulated midbody transverse fracture of the proximal sesamoid bone in horses. Vet Surg. 2004 May-Jun;33(3):253-62

    11. Chuckpaiwong B, Easley ME, Glisson RR. Screw placement in subtalar arthrodesis: a biomechanical study. Foot Ankle Int. 2009 Feb;30(2):133-41

    10

    http://www.ncbi.nlm.nih.gov/pubmed/12172281