ALPS Reports

Inauen R, Koch D, Bass M.

Arthrodesis of the tarsometatarsal joints in a cat with a two hole advanced locking plate system.

Koch&Bass Referal Practice for Small Animal Surgery, Basadingerstrasse 26, 8253 Diessenhofen, Switzerland.
This report describes the successful use of the novel fixed-angle locking plating system ALPS (advanced locking plate system) in the case of dorsal tarsometatarsal instability in a cat. Partial arthrodesis of the tarsometatarsal joint was performed with a two hole ALPS 5 and two 2.4 mm selftapping locking screws through a small dorsal approach. Five days after the surgery…


Schlegel U, Perren SM.

Surgical aspects of infection involving osteosynthesis implants: implant design and resistance to local infection.

AO Research Institute, AO Foundation, Davos, Switzerland.
May 2006
Infection is still a major complication associated with surgery in orthopedics and traumatology. The implant design, the implant material, and the implantation technique may play essential roles in preventing infection. The goal of this paper is to discuss a series of experiments evaluating different aspects of both surgical…


Perren SM.

Backgrounds of the technology of internal fixators.

AO Research Institute, Davos, Switzerland.
November 2003
PMID: 14580979 [PubMed - indexed for MEDLINE]


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.

AO Research and Development Institutes, Davos, Switzerland.
November 2002
The advent of ‘biological internal fixation’ is an important development in the surgical management of fractures. Locked nailing has demonstrated that flexible fixation without precise reduction results in reliable healing. While external fixators are mainly used today to provide temporary fixation in fractures after severe injury, the internal…


Eijer H, 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.

Department of Orthopaedic Surgery, University Hospital Amsterdam, The Netherlands.
September 2001
Bacterial infection is still one of the main complications after internal fixation of fractures. The design of implants influences local infection resistance. To reduce the development of infections around implants after internal fixation, the vitality of the bone should be preserved to optimize cellular and humoral host defense…


Hertel R, 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.

Department of Orthopaedic Surgery, Inselspitel, University Berne, Switzerland.
September 2001
The Point Contact-Fixator (PC-Fix) was designed as part of the developmental evolution of more biological devices for internal fixations. It is a device characterized by minimal contact to the underlying periosteum and bone, hereby minimizing potential damage to perfusion. A multicentre handling test was conducted in 1993 and 1994 in six hospitals to assess its performance. A total of 83 fractured forearm bones (34 radii and 49 ulnae) in…


Haas N, 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).

Clinic for Trauma and Reconstructive Surgery, Charité, Humboldt University, Berlin, Germany.
September 2001
Fractures of the forearm are considered to be a very good indication for plating. Conventional plating is still technically demanding. Extensive animal studies show that there is potential for improvement. The method consists of using an internal fixator that minimizes implant contact to the bone to reduce biological damage. Furthermore, foregoing the need for precise reduction and interfragmental compression…


Arens S, 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.

OBJECTIVES: Comparison of infection resistance after local bacterial challenge associated with two different designs for fixation implants: the conventional dynamic compression plate (DCP) and the point contact fixator (PC-Fix). DESIGN: Randomized, prospective study in experimental animals. Grouped sequential experimental procedure. Observation time was twenty-eight days, with twenty animals per…


Fernández Dell'Oca AA, Tepic S, Frigg R, Meisser A, Haas N, Perren SM.

Treating forearm fractures using an internal fixator: a prospective study.

British Hospital, Montevideo, Uruguay.
August 2001
Some major complications of internal fixation with plates, such as infections and disturbance of healing, have been shown to be related to necrosis of bone and to the soft tissues immediately deep to the plate. This is attributable to plate contact. To deal with this phenomenon, an internal fixator, the Point Contact Fixator, was developed according to a new concept. The Point Contact Fixator resembles a plate but…


Hauke C, Meisser A, Perren SM.

Methodology of clinical trials focusing on the PC-Fix clinical trials.

Once development and mechanical and biological laboratory testing have been completed, new technologies to be used in orthopaedic and trauma surgery must be investigated in humans before they can be used routinely. Prospective clinical investigations with or without randomization to standard treatments conducted according…


Tepic S, 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.

Research Institute, AO/ASIF Foundation, Davos, Switzerland.
January 1997
OBJECTIVES: Comparison of fracture healing with two different implants: a conventional Dynamic Compression Plate (DCP) and a new internal Point Contact Fixator (PC-Fix). DESIGN: Randomized, prospective study in experimental animals. Observation times: 12, 24, 48 and 96 weeks, with six sheep per group. SETTING: Following surgery, animals were kept with unrestricted weight-bearing in individual stalls for…


Arens S, 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.

AO/ASIF Research Institute, Davos, Switzerland.
Infection rates for open reduction and internal fixation (ORIF) with the DCP in clinical studies are based on heterogeneous data on general risk factors and do not take into account the direct effect of the implant (material, design, surface, technique). The initial degree of bacterial contamination is generally unknown and the applied…


Ungersböck A, 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.

Department of Orthopaedic Surgery, University of Bern, Switzerland.
April 1996
Five types of limited contact dynamic compression plates (LC-DCPs) of pure titanium with different surface treatments and an electropolished stainless steel LC-DCP were tested. The surface roughness parameters and chemical surface conditions were determined and checked for probable surface contamination. After an implantation period…


Miclau T, 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.

Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
February 1995
Cortical bone porosis associated with the dynamic compression plate (DCP) prompted the development of the limited-contact dynamic compression plate (LC-DCP) and the point-contact fixator (PC-Fix) to increase bone vascularity. However, the comparative fixation characteristics of the three designs are unknown. Transverse…


Ungersböck A, Pohler O, Perren SM.

Evaluation of the soft tissue interface at titanium implants with different surface treatments: experimental study on rabbits.

AO/ASIF Research Institute Davos, Switzerland.
Recently, a dominant influence of the surface roughness parameters for the soft tissue reaction at the implant tissue interface was found in an experimental study on sheep. The purpose of the present study is to correlate the surface roughness parameters of different experimental bone plates to the results of the histomorphometric analyses…