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ACL-Friendly Test-Arm


     Introducing New ACL-Friendly Test Arm (sm) to validate, demonstrate, and/or calibrate the ACL and MCL injury-mitigation function of forthcoming new Howell SkiBindings.  Uses simple leverage to test the proper magnitude of the lateral-heel release function of the complete ski-boot-binding system. ‘Just push (or pull) the numbered-section of the test-bar according to the special chart that’s supplied.

     ‘Binding shown is a still-top-rated 1986 Geze 952 TC that does NOT provide lateral-heel release:  this test-device also exposes how ACL-rupture can take-place even with the best of ordinary bindings.

     ‘Can also be used to test AT-bindings for ACL release function — noting importantly that pure AT-pin bindings can cause severe tibia tuberosity fracture irrespectively of any ‘release setting’.

     Adopts seamlessly to ‘foot’ supplied-separately by Vermont Safety Research (Vermont Safety Research is NOT affiliated with Howell SkiBindings).  Requires calibration of ordinary torsional release torque according to industry-standards prior to testing lateral-heel release function (using the separately-supplied foot).  

     ACL-Friendly Test-Arm is intended for ski shop use — but can be purchased by anyone — to precisely tune the ACL and MCL integrity function of Howell SkiBindings.



(1)  All three visual release indicators on each left and right Howell SkiBinding should be set according to the Howell SkiBindings ‘Recommended Release Setting’ chart, which chart conforms with ISO 9462 and ISO 8061.  Boots must conform to ISO 5355 — the international alpine ski boot standard (no metal dimples for pin-bindings).

(2)  Calibrate the torsional release torque of Howell SkiBindings according to the ‘Recommended Release Settings’ chart provided by Howell SkiBindings using a release torque measuring device such as the Vermont Release Calibrator by Vermont Safety Research (Vermont Safety Research is NOT affiliated with Howell SkiBindings).

(3) Remove the torsional release torque wrench from the foot — then attach the ACL-Friendly Test Arm to the foot — with the numbered-section of test-arm positioned over the rear-section of the ski.

(4)  Select a numerical ‘Transition-Point’ from the special ACL-Friendly Release Chart supplied by Howell SkiBindings:  see photo gallery, above (for use ONLY with Howell SkiBindings).   If other bindings are tested — the outcome is purely for demonstration:  other bindings must NOT be used on-snow / in-skiing in conjunction with this process.

(5)  Push (or pull) the numbered-section of the test-arm where the test-arm displays a centimeter-numbered measurement-scale:

(5.a)  Push (or pull) at a point on the test arm slightly aft of the selected Transition-Point — to cause lateral-toe release;

(5.b)  Push (or pull) at a point on the test arm slightly forward of the selected Transition-Point — to cause lateral-heel release.

(6)  If lateral-toe release — or respectively lateral-heel release — does not take place as noted in point #5.a AND #5.b, do NOT change the magnitude of the lateral-toe release / do NOT change the torsional release torque.  Change ONLY the lateral-heel release setting — provided however that no change in the lateral-heel release setting is greater than one-and-a-half lateral-heel visual release indicator numbers.

(7)  If a change of more than one-and-a-half lateral-heel release visual indicator numbers is required to cause the function described in points #5.a AND #5.b — a list of ‘Troubleshooting Actions’ is provided by Howell SkiBindings to cause the function specified in points #5.a AND #5.b.  See full-instructions including Troubleshooting Actions supplied with ACL-Friendly Test-Arm and Howell SkiBindings Operations Manual.

(8)  If after applying the Troubleshooting Actions provided by Howell SkiBindings the function described in points #5.a AND #5.b is still not occurring — the binding, the boot, or both — are defective and/or incompatible.  
WARNING: in this scenario #8 — ACL-integrity and/or MCL-integrity is compromised.

In all scenarios above, ordinary lateral-toe release / ordinary torsional release torque will remain true and correct:  the tibia-integrity function of Howell SkiBindings will remain true and correct.

(9)  In normal / typical operation, the function described in points #5.a AND #5.b occurs true and correct in Howell SkiBindings without readjustment of the lateral-heel release setting.

Using the ACL-Friendly Test-Arm is simple and fast — taking only a few minutes. 

     ACL-Friendly Test-Arm validates, demonstrates, and calibrates the ACL and MCL integrity-function of the complete ski-boot-binding system that includes Howell SkiBindings.


Biomechanical Proof

     ACL-Friendly Test-Arm is based on 19-years of biomechanical research by Rick Howell as Principal Investigator — peer-reviewed and approved by Scientific Committees — and presented at:

     International Society for Skiing Safety (ISSS) Pontresina, Switzerland, 2003 (presented by University of Montréal researchers based on a 2001 grant-application promulgated by Rick Howell — all other presentations listed below, investigated / enhanced / and presented by Rick Howell);  Niigata, Japan, 2005;  Aviemore, Scotland, 2007;  Bariloche, Argentina, 2013;  Cortina, Italy, 2015;  Innsbruck, Austria, 2017;  Squaw Valley, USA, 2019;  

     International Medical Society for Skiing Safety [SITEMSH':   Société Internationale de Traumatologie et Médicine des Sports d’Hiver] (SITEMSH) Flachau, Austria, 2014;  Inawashiro, Japan, 2016;  Barcelona, Spain, 2018;

     International Olympic Committee on Prevention of Injury in Sport (IOC), Monte Carlo, Monaco, 2017;

     European Society for Knee Surgery, Arthroscopy and Sports Traumatology (ESSKA), Barcelona, Spain, 2016;  and

     International Society for Science in Skiing (ICSS), Voukatti, Finland, 2019;

     ... as well as at 2 forthcoming scientific-medical (skiing-safety biomechanics) conferences postponed in 2020 due to the c-virus.


ACL-Friendly Test-Arm — is available now for shipment.


‘ACL-Friendly Test-Arm’ (sm) is a Service Mark of Howell SkiBindings / Howell Product Development Holding, Inc. of Stowe, Vermont, USA.

Copyright © by Howell SkiBindings, Howell Product Development Holding, Inc., and Rick Howell, 2020.  All rights reserved.