The Original Advanced Locking Plate System


“Biological internal fixation” involves the use of locked internal fixators, which have minimal implant-to-bone contact, long-span bridging and fewer screws for fixation.[1] The Advanced Locking Plate System (ALPS)* is a biological internal fixation system that was designed from the beginning to protect the bone, provide stability and promote rapid healing.

The ALPS plating system builds on research and development work done on the PC-Fix (Point Contact Fixitor) in the 1980’s and 1990’s at the AO Research Institute, Davos, Switzerland. Numerous publications have documented the PC-Fix design and clinical results. Please see the Reports section for references. Currently an in vitro study comparing ALPS plates with other plates is ongoing at the Cummings School of Veterinary Medicine at Tufts University. Results will be referenced once the study is complete and published.

Increased resistance to infection and faster, more consistent healing are all but certain benefits to come from clinical applications. Versatility of the plates with bending in both planes, as well as their geometry optimized for strength and soft tissue cover, are also considered worthwhile improvements over state of the art in internal fracture fixation. By the end of 2009, the ALPS had been used in over 1,000 dogs and cats by more than 50 surgeons in Europe, the Americas, and Japan.


  • Reduced damage to vascular supply
  • Increased resistance to infection
  • Accelerated healing


  • Titanium and titanium alloy for supreme biocompatibility
  • Locking or regular screws in all holes
  • Eliminated fretting
  • Geometry optimized for strength
  • Bending possible in both planes
  • Sizing from cats to horses

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[1] – Perren SM, – Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology.
J Bone Joint Surg Br. 2002 Nov;84(8): 1093-110.
*patented/patent pending




1. Minimize vascular damage to both periosteum and endosteum;
2. Allow adaptation in both planes, yet exceed the strength of conventional plates;
3. Accept both regular and locking screws in all holes;
4. Use superiorly biocompatible titanium and titanium alloys.

Vascular damage is minimal because:

  • The underside of ALPS plates allows for only very small contact areas to the bone, reducing compression of periosteal blood vessels; and
  • The endosteal blood supply is spared through preferred use of locking, monocortical screws – drilling depth is controlled with a drill stop limiting vascular damage within the medullary canal.

Adaptation to bone geometry by bending in both planes is facilitated by:

  • The computer-optimized shape of the plate, resembling the early Sherman plate; and
  • The use of unique bending pliers for in-plane bending and modified bending irons for out-of-plane bending, designed to protect the holes.

Geometry of the screw heads and of the screw holes permit use of either:

  • Conventional bone screws, with ±30° longitudinal and ±5° transverse swivel, either in neutral or compression mode. The screw holes are tapered to squeeze the screw heads, preventing unscrewing; and
  • Locking screws, preferred as long as the cortex thickness is sufficient – near the joints one can use either longer locking screws, or conventional bicortical ones.

ALPS uses only titanium or titanium alloys for all of its implants:

  • They allow bone and soft tissue to make a close, adhering contact at the interfaces, preventing formation of a fluid filled gap – a major risk for seeding and spread of infection; and
  • Their superior mechanical properties, with a favorable tradeoff between ductility and strength.

Highly advanced manufacturing technologies used by KYON suppliers to produce the implants and instruments of the ALPS have given us an opportunity to provide veterinary surgeons with the most advanced, yet affordable plating system.


• ALPS plates minimize contact with the periosteum and thus reduce the iatrogenic insult to bone perfusion common with conventional compression plates

• Preserving perfusion significantly reduces the risk of infection and accelerates bone healing

• Resistance to infection with ALPS is also increased by the biocompatibility of titanium and the absence of fretting

ALPS-Slide1-KYON Underside view of ALPS plate

Side view

Top view
ALPS-Slide2-KYON Self-tapping locking and regular screws with an RU recess (a unique recess that is compatible with TORX®) plus a hole plug
ALPS-Slide3-KYON Plate holes accept either screw type
ALPS-Slide4-KYON Plates can be bent in both planes as needed
ALPS-Slide5-KYON Regular screws can be inserted neutrally with ± 30° longitudinal and ± 5° transverse swivel

Advanced Locking Plate System is patented/patent pending


Vascular Damage in Fracture Plating: An Introduction

In the late seventies and early eighties, in vivo experimental animal studies produced convincing evidence that early temporary porosis, commonly observed under conventional bone plates, resulted from an insult to periosteal blood circulation caused by implant-bone contact. Deprived of blood perfusion, the bone turned necrotic, then sclerotic, before undergoing remodelling through neovascularization. The result was early, frequently persistent porosis. While in most cases, the end result was still bony union, many of the major complications of internal fixation can be linked to the vascular damage caused by surgical intervention and the implants used. Infection tops the list.

Reducing Vascular Damage: Methods

Two engineering proposals from the Straumann Institute, Waldenburg, provided early leads:

(i) Brunner proposed to increase dynamic compression plate (DCP) deformation tolerance in fatigue by transverse undercuts between the screw holes, evening out longitudinal variation in plate stiffness;
(ii) Sutter developed a mandibular reconstruction locking plate system.

In vivo testing of the Brunner plate provided some of the most convincing evidence linking bone remodelling to perfusion damage. Sutter’s in vitro testing of the locked vs. conventional plates demonstrated the mechanical advantages of locked screws.

Research & Development: PC-Fix to LC-DCP

Combining the two proposals with a novel technique, locking the screw by means of friction between a conical head and a conical hole in the plate, Dr. Slobodan Tepic initiated the development of a new plating system, PC-Fix, or Point Contact Fixator, by AO.

Approximately eight years of testing on animals demonstrated some anticipated and some surprising advantages of PC-Fix when compared to conventional plating:

• Significantly increased resistance to infection;
• Faster, more consistent, healing;
• Reduced impact on bone remodelling.

Read reports on PC-Fix>>

PC-Fix was then taken into the clinical setting in both human and veterinary applications. A large, multi-centre clinical trial on forearm fractures largely met the expectations, but the system was never commercialized.

Elucidation, of the role played by vascular damage resulting from internal fixation plates, provided fertile ground for innovation in the past three decades. A spur of activity, in R&D and marketing in the eighties, resulted in the release of the Synthes LC-DCP system. LC-DCP featured a modification in design and established titanium as the metal of choice, but the surgical principles of application remained the same. While the PC-Fix system was never commercialized, the locking screw principle caught the attention of both the industry and the surgical community. Within a very short period of time, locking has become a standard feature on just about every internal fixation system. Technical solutions also proliferated, but the main message of the research that started it all — the crucial role of blood perfusion in the process of healing – was still looking for an audience.

Moving Forward: The Advanced Locking Plate System (ALPS)

Dr. Tepic, who conducted the research on PC-Fix, developed the Advanced Locking Plate System (ALPS) as a “biological internal fixation” [1] system, designed from conception to preserve the vascular supply, increase resistance to infection and accelerate healing. “Biological internal fixation” involves the use of locked internal fixators, which have minimal implant-to-bone contact, long-span bridging and fewer screws for fixation.

ALPS has not been used on any experimental animals, nor has it been tested in a clinical trial, but its main features related to the bone contact and fixation method are very similar to PC-Fix, suggesting that most, if not all of the observations from the PC-Fix project are highly relevant to ALPS, and specifically those related to infection.

The ALPS plate is a combination of Shermann (1907) and Brunner plates, with holes, providing for use of either conventional or locking screws. The shape of the plate allows for bending in both planes. The plate material is c.p. titanium; for the screws, titanium alloy. Finite Element Analysis was used to optimize the shape of the plate. Three sizes, designated by the width of the plate (5, 8 and 10mm), suitable for small animals are currently available, with additional sizes coming soon. Since ALPS’ commercial release in the spring of 2007, 50 surgeons have used ALPS on over 1,000 clinical cases. Anecdotal evidence is positive. Increased resistance to infection and faster, more consistent healing are all but certain benefits to come from further clinical applications.

Currently, an in vitro study, comparing ALPS plates with other plates, is ongoing at the Cummings School of Veterinary Medicine at Tufts University. Results will be referenced once the study is complete and published.
Advanced Locking Plate System is patented/patent pending
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ALPS-Slide6-KYON Use a core diameter drill bit for the hole to be tapped

Use the outer diameter drill bit with the double sleeve guide for the lag hole

The nose on the core diameter drill sleeve limits the range of the swivel
ALPS-Slide7-KYON Use the compression sleeve to achieve dynamic fracture compression with regular screws
ALPS-Slide8-KYON Use the locking screw sleeve to drill for locking screws

Locking screws are only installed perpendicular to the plate
ALPS-Slide9-KYON Before drilling adjust the drill stop position to avoid unintended far side drill penetration

The drill should protrude from the sleeve by 2mm more than the screw length
ALPS-Slide10-KYON It is preferable to use locking screws

Use the lag screws at their best position, do not insist on lagging through the plate
ALPS-Slide11-KYON Always attempt to place a transverse undercut over the fracture

Avoid placing screws too close to the fracture
ALPS-Slide12-KYON Double plating with ALPS is an admissible alternative to lagging

For the second plate, a plate one size smaller and shorter is preferred
ALPS-Slide13-KYON Proper placement of the plate in the bending irons for concave bending

For best control and ease of use, pull apart the ends of the irons
ALPS-Slide14-KYON Proper placement of the plate in the bending irons for convex bending

Proceed hole-to-hole for sharp bends
Use plugs for excessive bends
ALPS-Slide15-KYON Caution! Avoid bending plates back-and-forth

Titanium does not tolerate cycling in the plastic range as well as stainless steel
ALPS-Slide16-KYON For in-plane bending use the special bending instrument

Close the handles, drop the plate between the cylinders and pull the handles apart to bend

For most applications, only a slight in-plane bend is indicated

Advanced Locking Plate System is patented/patent pending



The following database, contains contact information for surgeons who use ALPS implants and instruments.

Please contact to update contact information.


Niederhäuser SK1, Tepic S2, Weber UT1.
Effect of screw position on single cycle to failure in bending and torsion of a locking plate–rod construct in a synthetic feline femoral gap model
American Journal of Veterinary Research. 2015 May; 76(2):402-410. doi: 10.2460/ajvr.76.5.402
1Tierärztliches Überweisungszentrum, Small Animal Referral Practice, CH-4456 Tenniken, Switzerland.
2Kyon AG, Technoparkstrasse 1, CH-8005 Zurich, Switzerland


Nojiri A1, Akiyoshi H, Ohashi F, Ijiri A, Sawase O, Matushita T, Takemoto M, Fujibayashi S, Nakamura T, Yamaguchi T1
Treatment of a unicameral bone cyst in a dog using a customized titanium device
J Vet Med Sci. 2015 Jan; 77(1): 127–131. doi: 10.1292/jvms.13-0548
1Fabre Animal Medical Center, 4–8 Minaminoguchi-cho, Kadoma, Osaka 571– 0065, Japan


Guerrero TG1, Kalchofner K, Scherrer N, Kircher P.
The Advanced Locking Plate System (ALPS): a retrospective evaluation in 71 small animal patients.
Vet Surg. 2014 Feb;43(2):127-35. doi: 10.1111/j.1532-950X.2014.12097.x. Epub 2014 Jan 6.
1Department for Small Animal Surgery, Vetsuisse Faculty University of Zurich, Zurich, Switzerland; Small Animal Medicine and Surgery Academic Program, School of Veterinary Medicine, St. George’s University, True Blue, Grenada, West Indies.


Pozzi A1, Peck JN, Chao P, Choate CJ, Barousse D, Conrad B.
Mechanical evaluation of adjunctive fixation for prevention of periprosthetic femur fracture with the Zurich cementless total hip prosthesis.
Vet Surg. 2013 Jun;42(5):529-34. doi: 10.1111/j.1532-950X.2013.12018.x. Epub 2013 Jun 3.
1Department of Small Animal Clinical Sciences, Comparative Orthopaedics and Biomechanics Laboratory, University of Florida, College of Veterinary Medicine, Gainesville, Florida, USA.


Blake CA1, Boudrieau RJ, Torrance BS, Tacvorian EK, Cabassu JB, Gaudette GR, Kowaleski MP.
Single cycle to failure in bending of three standard and five locking plates and plate constructs.
Vet Comp Orthop Traumatol. 2011;24(6):408-17. doi: 10.3415/VCOT-11-04-0061. Epub 2011 Sep 21.
1Department of Clinical Sciences, Tufts University, North Grafton, MA 01536, USA.


Cabassu JB1, Kowaleski MP, Skorinko JK, Blake CA, Gaudette GR, Boudrieau RJ.
Single cycle to failure in torsion of three standard and five locking plate constructs.
Vet Comp Orthop Traumatol. 2011;24(6):418-25. doi: 10.3415/VCOT-11-04-0050. Epub 2011 Sep 21.
1Department of Clinical Sciences, Tufts University, North Grafton, MA 01536, USA.


Inauen R1, Koch D, Bass M.
Arthrodesis of the tarsometatarsal joints in a cat with a two hole advanced locking plate system.
Vet Comp Orthop Traumatol. 2009;22(2):166-9.
1Koch&Bass Referal Practice for Small Animal Surgery, Basadingerstrasse 26, 8253 Diessenhofen, Switzerland.


Schlegel U1, Perren SM.
Surgical aspects of infection involving osteosynthesis implants: implant design and resistance to local infection.
Injury. 2006 May;37 Suppl 2:S67-73.
1AO Research Institute, AO Foundation, Davos, Switzerland.


Perren SM.
Backgrounds of the technology of internal fixators.
Injury. 2003 Nov;34 Suppl 2:B1-3.
AO Research Institute, Davos, Switzerland.


Perren SM.
Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology.
J Bone Joint Surg Br. 2002 Nov;84(8):1093-110.
AO Research and Development Institutes, Davos, Switzerland.


Eijer H1, Hauke C, Arens S, Printzen G, Schlegel U, Perren SM.
PC-Fix and local infection resistance–influence of implant design on postoperative infection development, clinical and experimental results.
Injury. 2001 Sep;32 Suppl 2:B38-43.
1Department of Orthopaedic Surgery, University Hospital Amsterdam, The Netherlands.


Hertel R1, Eijer H, Meisser A, Hauke C, Perren SM.
Biomechanical and biological considerations relating to the clinical use of the Point Contact-Fixator–evaluation of the device handling test in the treatment of diaphyseal fractures of the radius and/or ulna.
Injury. 2001 Sep;32 Suppl 2:B10-4.
1Department of Orthopaedic Surgery, Inselspitel, University Berne, Switzerland.


Haas N1, Hauke C, Schütz M, Kääb M, Perren SM.
Treatment of diaphyseal fractures of the forearm using the Point Contact Fixator (PC-Fix): results of 387 fractures of a prospective multicentric study (PC-Fix II).
Injury. 2001 Sep;32 Suppl 2:B51-62.
1Clinic for Trauma and Reconstructive Surgery, Charité, Humboldt University, Berlin, Germany.


Arens S1, Eijer H, Schlegel U, Printzen G, Perren SM, Hansis M.
Influence of the design for fixation implants on local infection: experimental study of dynamic compression plates versus point contact fixators in rabbits.
J Orthop Trauma. 1999 Sep-Oct;13(7):470-6.
1AO ASIF Research Institute, Davos, Switzerland.


Fernández Dell’Oca AA1, Tepic S, Frigg R, Meisser A, Haas N, Perren SM.
Treating forearm fractures using an internal fixator: a prospective study.
Clin Orthop Relat Res. 2001 Aug;(389):196-205.
1British Hospital, Montevideo, Uruguay.


Hauke C1, Meisser A, Perren SM.
Methodology of clinical trials focusing on the PC-Fix clinical trials.
Injury. 2001 Sep;32 Suppl 2:B26-37.
1AO ASIF Development Clinical Investigation, Davos-Platz, Switzerland.


Tepic S1, Remiger AR, Morikawa K, Predieri M, Perren SM.
Strength recovery in fractured sheep tibia treated with a plate or an internal fixator: an experimental study with a two-year follow-up.
J Orthop Trauma. 1997 Jan;11(1):14-23.
1Research Institute, AO/ASIF Foundation, Davos, Switzerland.


Arens S1, Hansis M, Schlegel U, Eijer H, Printzen G, Ziegler WJ, Perren SM.
Infection after open reduction and internal fixation with dynamic compression plates–clinical and experimental data.
Injury. 1996;27 Suppl 3:SC27-33.
1AO/ASIF Research Institute, Davos, Switzerland.


Ungersböck A1, Pohler OE, Perren SM.
Evaluation of soft tissue reactions at the interface of titanium limited contact dynamic compression plate implants with different surface treatments: an experimental sheep study.
Biomaterials. 1996 Apr;17(8):797-806.
1Department of Orthopaedic Surgery, University of Bern, Switzerland.


Miclau T1, Remiger A, Tepic S, Lindsey R, McIff T.
A mechanical comparison of the dynamic compression plate, limited contact-dynamic compression plate, and point contact fixator.
J Orthop Trauma. 1995 Feb;9(1):17-22.
1Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX 77030, USA.


Ungersböck A1, Pohler O, Perren SM.
Evaluation of the soft tissue interface at titanium implants with different surface treatments: experimental study on rabbits.
Biomed Mater Eng. 1994;4(4):317-25.
1AO/ASIF Research Institute Davos, Switzerland.