The Zespol Contribution to Locking Plate Osteosynthesis

Kenneth A. Johnson, MVSc, PhD, FACVSc, DACVS, DECVS

Maria Podsiedlik, DVM, MSc, DACVS (Small Animal)

Implementation of locking bone plate fixation of fractures in humans was first described over 40 years ago, not by Swiss surgeons, but by a group of Polish surgeons in Warsaw. This Polish method of osteosynthesis goes by the name of the Zespol method.

The Zespol plate was applied with little or no contouring and locked using special platform screws and nuts, patented in 1979. The plates were positioned either just outside the skin (called external or supracutaneous) or inside the soft tissue envelope; either adjacent to the bone – but not in contact with the bone (called paraosseous) or above the muscles and below the skin (called subcutaneous). Lack of contact between the plate and a bone surface was crucial in this system, allowing for preservation of a periosteal blood supply, therefore, enhancing bone healing.

Descriptions of the Zespol implant design, mechanical performance and clinical application are documented in detail in a textbook published in 1988 and other publications.[1] [2] [3] However, the propagation of knowledge about the Zespol methods to the rest of the orthopaedic world was possibly hampered by the political climate in Poland in that era, as well as language barriers.

About a decade later, AO Foundation researchers and surgeons also embarked upon the development of locking plate technology. First came the Point Contact Fixator, which had a conical coupling locking mechanism of screw head engagement into the plate hole.[4] The Point Contact Fixator was soon abandoned despite showing positive results, but it later re-emerged as the ALPS plate by Kyon.[4] Next was the Less Invasive Stability System (LISS) for distal femoral and proximal tibial fractures. The LISS plate then transitioned to the Locking Compression Plate (LCP) with the more versatile Combi Hole. This ushered in a completely new concept in osteosynthesis that has been adopted, adapted, and copied by others.

The biological advantages of minimally invasive surgical techniques of fracture osteosynthesis started to achieve greater prominence thanks to these developments in locking plate technology. The value of these surgical techniques of making smaller incisions and minimizing soft tissue surgical trauma through the creation of epi-periosteal tunnels for plates was recognized as a key factor in the support of the fracture healing process and reducing fracture-related infections.[5] [6]

The clinical communication in this issue of the journal reports the management of tibial and antebrachial fractures in dogs and cats using supracutaneous locking plates, according to the Zespol methodology.[7] The type of locking plates used in these cases was different from those in some previous reports, but the concept is similar to the Zespol methods. It can be predicted that an increase in the offset distance of the locking plate from the underlying bone, and also increased screw length, will decrease construct stiffness; this is a topic that needs more investigation from both a biological and mechanical perspective. It has also been suggested that the second locking plate in orthogonal bridge plate fixation could be supracutaneous; this might facilitate postoperative imaging of fracture healing as well as allow staged-implant removal.

Publication History

Article published online:
12 September 2025

• References

• 1 Ramotowski W, Granowski R, Bielawski J. Osteosynteza metoda Zespol: teoria I praktyka kliniczna (Zespol Osteosynthesis Theory and Clinical Practice). Warzawa: Panstwowy Zaklad Wydawnictw Lekarskich; 1988
• 2 Hopf T, Osthege S. Interfragmental compression of the Zespol osteosynthesis system. Experimental biomechanical studies [In German]. Z Orthop Ihre Grenzgeb 1987; 125 (05) 546-552
• 3 Hopf T, Albert H. Tensile strength of plate osteosynthesis. Comparative biomechanical study of the original autocompression plate and a functional modification using the ZESPOL principle [In German]. Unfallchirurg 1990; 93 (03) 100-104
• 4 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. J Orthop Trauma 1997; 11 (01) 14-23
• 5 Farouk O, Krettek C, Miclau T, Schandelmaier P, Guy P, Tscherne H. Minimally invasive plate osteosynthesis and vascularity: preliminary results of a cadaver injection study. Injury 1997; (28 Suppl 1): A7-A12
• 6 Tong GO, Bavonratanavech S. AO Manual of Fracture Management. Minimally Invasive Plate Osteosynthesis (MIPO). Davos, Switzerland: AO Publishing; 2007
• 7 İnal KS. Minimally invasive radial–ulnar and tibial fracture management with supracutaneous locking plates in dogs and cats. Vet Comp Orthop Traumatol 2025; 38 (05) 254–-262