Research Papers

Design of a Dynamic External Finger Fixator

[+] Author and Article Information
May M. Youssef

School of Mechanical Engineering,
University of Birmingham,
Birmingham B15 2TT, UK
e-mail: mmy179@bham.ac.uk

Duncan E. T. Shepherd

School of Mechanical Engineering,
University of Birmingham,
Birmingham B15 2TT, UK
e-mail: d.e.shepherd@bham.ac.uk

O. Garth Titley

Queen Elizabeth Hospital,
Birmingham B15 2TH, UK
e-mail: Garth.Titley@uhb.nhs.uk

Manuscript received October 28, 2015; final manuscript received March 14, 2016; published online August 5, 2016. Assoc. Editor: Rita M. Patterson.

J. Med. Devices 10(4), 041004 (Aug 05, 2016) (6 pages) Paper No: MED-15-1286; doi: 10.1115/1.4033602 History: Received October 28, 2015; Revised March 14, 2016

This paper describes an improved design of an external fixator. The new fixator comprises 13 parts which are assembled together. The proposed device materials consist of polyether ether-ketone (PEEK) and stainless steel 316L. The design was subjected to finite-element analysis, and a working model was manufactured and subjected to cyclic mechanical testing. The finite-element analysis showed that the maximum stress was 242.9 MPa and this was less than the yield strength and the fatigue endurance limits for the selected materials. Mechanical testing showed that testing reached run-out of 170,000 cycles with no cracks or damage visible in the device parts.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.


Houshian, S. , Jing, S. S. , Chikkamuniyappa, C. , Kazemian, G. H. , and Tehrani, M. E. , 2013, “ Management of Posttraumatic Proximal Interphalangeal Joint Contracture,” J. Hand Surg. Am., 38(8), pp. 1651–1658. [CrossRef] [PubMed]
Salafia, A. , and Chauhan, G. , 1997, “ Joshi External Stabilising System (JESS) in Proximal Interphalangeal Joint (PIP) Contractures in Leprosy,” Indian J. Lepr., 69(4), pp. 331–340. [PubMed]
Messina, A. , and Messina, J. , 1993, “ The Continuous Elongation Treatment by the TEC Device for Severe Dupuytren's Contracture of the Fingers,” J. Plast. Reconstr. Surg., 92(1), pp. 84–90. [CrossRef]
Fahmy, N. R. , 1990, “ The Stockport Serpentine Spring System for the Treatment of Displaced Comminuted Intra-Articular Phalangeal Fractures,” J. Hand Surg., 15(3), pp. 303–311. [CrossRef]
Hodgkinson, P. D. , 1994, “ Use of Skeletal Traction to Correct the Flexed PIP Joint in Dupuytren's Disease,” J. Hand Surg. Br., 19(4), pp. 534–537. [CrossRef] [PubMed]
Neil, C. N. , and Messina, J. C. , 1998, “ The Use of Skeletal Traction in the Treatment of Severe Primary Dupuytren's Disease,” J. Bone Jt. Surg., Br., 80, pp. 126–129. [CrossRef]
Kasabian, A. , McCarthy, J. , and Karp, N. , 1998, “ Use of a Multiplanar Distracter for the Correction of a Proximal Interphalangeal Joint Contracture,” J. Ann. Plast. Surg., 40(4), pp. 378–381. [CrossRef]
Ng, C. Y. , and Oliver, C. W. , 2009, “ Fractures of the Proximal Interphalangeal Joints of the Fingers,” J. Bone Jt. Surg., Br., 91(6), pp. 705–712. [CrossRef]
Hotchkiss, R. , Hotchkiss, K. , and Woodward, A. , 1994, “ Dynamic Finger Support,” U.S. Patent No. 5,376,091.
Bonaspetti, G. , Volpi, P. , De Filippo, G. , Damiani, L. , and Pazzaglia, U. E. , 1999, “ L'utilizzo del Compass PIP Joint Hinge in Pazienti affetti da morbo di Dupuytren’ con Retrazione in Flessione dell'articolazione Interfalangea Prossimale,” Minerva Ortoped. Traumatologica, 50(3), pp. 103–106 (in Italian).
Bain, G. I. , Mehta, J. A. , Heptinstall, R. J. , and Bria, M. , 1998, “ Dynamic External Fixation for Injuries of the Proximal Interphalangeal Joint,” J. Bone Jt. Surg., Br., 80(6), pp. 1014–1019. [CrossRef]
Houshian, S. , Gynning, B. , and Schrøder, H. A. , 2002, “ Chronic Flexion Contracture of Proximal Interphalangeal Joint Treated With the Compass Hinge External Fixator. A Consecutive Series of 27 Cases,” J. Hand Surg., 27(4), pp. 356–358. [CrossRef]
Feldscher, S. B. , and Blank, J. E. , 2002, “ Management of a Proximal Interphalangeal Joint Fracture Dislocation With a Compass Proximal Interphalangeal Joint Hinge and Therapy: A Case Report,” J. Hand Ther., 15(3), pp. 266–273. [CrossRef] [PubMed]
Lahiri, A. , Mahmoud, M. M. , and Titley, O. G. , 2007, “ Management of Proximal Interphalangeal Joint Disorders With the Compass Hinge Dynamic External Fixator,” The British Society for Surgery of the Hand Annual Scientific Meeting, London, UK, Nov. 1–2.
Youssef, M. M. , Shepherd, D. E. T. , and Titley, O. G. , 2015, “ Engineering Analysis of a Failed Compass Proximal Interphalangeal (PIP) Joint Hinge,” Biomed. Eng.: Appl. Basis Commun., 27(2), p. 1550013. [CrossRef]
Walker, P. S. , and Erkman, M. J. , 1975, “ Laboratory Evaluation of a Metal Plastic Type of Metacarpophalangeal Joint Prosthesis,” Clin. Orthop. Relat. Res., 112, pp. 349–356. [CrossRef] [PubMed]
Lee, J. W. , and Rim, K. , 1990, “ Maximum Finger Force Prediction Using a Planar Simulation of the Middle Finger,” J. Eng. Med., 204(38), pp. 169–178. [CrossRef]
Reese, N. B. , and Bandy, W. D. , 2013, Joint Range of Motion and Muscle Length Testing, Elsevier Health Sciences, St. Louis, MO, p. 472.
Joyce, T. J. , and Unsworth, A. , 2000, “ The Design of a Finger Wear Simulator and Preliminary Results,” Proc. Inst. Mech. Eng., Part H, 214(5), pp. 519–526. [CrossRef]
Victrex, 2016, ” VICTREX® PEEK, Material Properties Guide,” Victrex plc, Lancashire, UK, http://www.victrex.com/en/victrex-peek
Carpenter Technology Corp., 2016, “ Carpenter BioDur™ 316LS Stainless Medical Implant Alloy, 90% Cold Worked,” MatWeb LLC, Blacksburg, VA.
HPC Gears, 2013, “ Catalogue C14 Gear Transmission Products,” HPC Gears Ltd., Chesterfield, UK.
Tilley, A. R. , and Associates, H. D. , 2002, The Measure of Man and Woman: Human Factors in Design, Wiley, New York, pp. 22–25.
BS EN ISO, 2010, “ Basic Human Body Measurements for Technological Design: Body Measurement Definitions and Landmarks,” British Standards Institute, London, Standard No. 7250-1.
Peebles, L. , and Norris, B. , 1998, “ Adult Data: The Handbook of Adult Anthropometric and Strength Measurements: Data for Design Safety,” Department of Trade and Industry, London, UK, pp. 134–142.
Alexander, B. , and Viktor, K. , 2010, “ Proportions of Hand Segments,” Int. J. Morphol., 28(3), pp. 755–758.
StrataSys, 2016, “ Laser Sintering Materials,” StrataSys Direct Manufacturing, Valencia, CA.
Trotignon, J. P. , Verdu, J. , Martin, C. H. , and Morel, E. , 1993, “ Fatigue Behaviour of Some Temperature-Resistant Polymers,” J. Mater. Sci., 28(8), pp. 2207–2213. [CrossRef]


Grahic Jump Location
Fig. 2

Assembled design of the new external dynamic protractor hinge fixator

Grahic Jump Location
Fig. 1

(a) Assembled compass hinge external fixator, with the individual parts numbered and (b) attached to a patient's finger

Grahic Jump Location
Fig. 3

Meshed finite-element model of the new fixator with the load 210N and constrains applied at position 1 gear teeth fixed at 15–30 deg. Arrows on teeth and axle indicate the constrains, and arrows on the clamping block indicate the forces.

Grahic Jump Location
Fig. 4

Assembled fixator in two different positions of engagement with the worm gear: (a) position 1 gear teeth fixed at 15–30 deg and (b) position 2 gear teeth fixed at 90–105 deg

Grahic Jump Location
Fig. 5

Working model of the external dynamic protractor hinge fixator that was manufactured using additive-manufacturing processes

Grahic Jump Location
Fig. 6

The setup used for the cyclic bending test of the working model

Grahic Jump Location
Fig. 7

Distribution of von Mises stresses for the model of the new fixator for position 1 gear teeth fixed at 15–30 deg



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In