Minimally Invasive Surgery by Angular Stability Systems in Proximal Tibia Fractures Biomechanical Characteristics and Preliminary Results

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2 Minimally Invasive Surgery by Angular Stability Systems in Proximal Tibia Fractures Biomechanical Characteristics and Preliminary Results P.D. Sirbu 1, E. Carata 2, T. Petreus 1, F. Munteanu 1, C. Popescu 3, R. Asaftei 1, and P. Botez 1 1 Gr.T.Popa University of Medicine and Pharmacy, Iasi, Romania 2 Gh. Asachi Technical University, Iasi, Romania 3 Prof. Dr. Nicolae Oblu Emergency Clinical Hospital, Iasi, Romania Abstract Complex fractures of the proximal tibia are difficult to treat. Minimally invasive plate osteosynthesis (MIPO) has determined the result improvement while the angular stability plate type Less Invasive Stabilization System proximal lateral tibia (LISS-PLT) or Locked Compression plate (LCP-PLT) were specially created for this kind of fractures. The purpose of this study was to emphasize the design and biomechanical characteristics of these systems as well as to evaluate the results following the treatment of the complex fractures on the proximal tibia by MIPO with these plates with angular stability. The authors emphasize the design of the plate, the concept of the internal fixator and the importance of the aiming device for percutaneous insertion. There were investigated 8 fractures of the proximal tibia in 8 patients, with a mean age of 39.5 years. Fractures were classified according to AO/ASIF in 2 type A3, 2 type C1, 2 type C2 and 2 type C3). There were three open fractures (1 type I and 2 type II) according to Gustilo. In all 8 cases we have performed minimally invasive plate osteosynthesis, using a LISS-PLT system in 5 cases or a LCP-PLT in 3 cases. All fractures healed after a mean time of 13 weeks and the knee mobility was considered as good (mean flexion of 105 ). Due to major biomechanical and biological advantages, the authors consider that, despite the high prices, the internal fixator type LISS-PLT or LCP-PLT represent the ideal implants for the complex fractures of proximal tibia. Keywords LISS-PLT, proximal tibia fractures, internal fixator, aiming device, angular stability. I. INTRODUCTION Complex fractures of the proximal tibia represent severe lesions that raise treatment problems. In displaced or unstable complex fractures (with/without articular involvement) the main indication is represented by the plate osteosynthesis [1]. The incidence of tegumentary necrosis, nonunions and infections is increased especially for the extended external and medial approach. These complications induce a decrease of the local blood flow due to excessive deperiostation and fragment devitalization. The disadvantages of the external placed plates determined authors as Krettek [2] to introduce MIPPO (minimally invasive percutaneous plate osteosynthesis) technique by medial approach. The main advantages are represented by the ease of molding technique and the subcutaneous placement, without deperiostation or blood flow limitations [3]. However, fixation with classic plates and screws has some limitations regarding immediate and secondary displacements as well as periosteal compression with blood flow reduction. The combination of four requirements for complex meta- and epiphyseal fractures (anatomical reduction, stable internal fixation, preservation of the blood supply and early active and painfree mobilization) has led to the development of a new generation of locked plates and instruments type LISS (Less Invasive Stabilization System). These systems were created mainly for MIPPO in distal femoral fractures [4] and recently for proximal tibia (LISS-PLT) [5,6] II. PURPOSE The purpose of this study is to emphasize the design and biomechanical characteristics of the locked plates type LISS-PLT and LCP-PLT (locked compression plate) as well as to evaluate the results following the treatment of the complex fractures on the proximal tibia by minimally invasive plate osteosynthesis with these plates with angular stability. III. MATERIAL AND METHODS A. Biomechanical Characteristics The LISS-PLT plate has the properties of an internal fixator (screws with threaded head that are locked in the round threaded holed in the plate). This determines the stability increase and eliminates the risks of the secondary displacement, due to an accidental lag between the screw and the plate. This plate differs totally from the classic one where the screws are tightened to fix and compress the plate onto the bone; the stability is due to the friction between the plate and the bone (Fig. 1A). For LISS-PLT, there is no contact between the bone and the internal fixator, so the periosteal blood supply is preserved. (Fig. 1B). S. Vlad, R.V. Ciupa, and A.I. Nicu (Eds.): MEDITECH 2009, IFMBE Proceedings 26, pp ,

414 P.D. Sirbu et al. Fig. 3 (A) LCP-PLT with combi-holes. (B) The concept of LCP with classical screw and locked screw Fig.

By comparison with LISS-PLT with round threaded holes (Fig.

brings the bone to the plate) or of the locked screws (in the threaded half of the hole) (fig.3).

3 414 P.D. Sirbu et al. Fig. 3 (A) LCP-PLT with combi-holes. (B) The concept of LCP with classical screw and locked screw Fig. 1 Distribution differences for the biomechanical load for standard plates (A) by comparison to LISS with unicortical screws (B) and boneimplant interface (adapted from Frigg R, Injury, 32, 2001) [4] By comparison with LISS-PLT with round threaded holes (Fig. 2) the introduction of Locked Compression Plates (LCP) with combi-hole [7] represented the next step in the evolution of the internal fixators by the possible placement of the classic screws (that brings the bone to the plate) or of the locked screws (in the threaded half of the hole) (fig.3). In order to increase the construct stability (bone-liss or LCP), a very complex pattern for the position and angulation of the proximal screws was developed in order to maximize the anchorage and purchase of the screws in proximal tibia (Fig.4). Fig. 4 (A-D) Position and angulation of the proximal screws in the LCP- PLT system Fig. 2 LISS-PLT plate with round threaded holes For optimal stability and for preserving the soft tissues, the internal fixator has to be placed very close to the bone. The plates are therefore preshaped (Fig. 5) and the midshaft is twisted to insure optimal position and fixation (Fig. 6). IFMBE Proceedings Vol. 26

4 1 Minimally invasive surgery by angular stability systems in proximal tibia fractures. Biomechanical characteristics and preliminary results. P.D. Sirbu 1, E. Carata 2, T. Petreus 1, Fl. Munteanu 1, C. Popescu 3, R. Asaftei 1, P. Botez 1 1 Gr.T.Popa University of Medicine and Pharmacy, Iasi, Romania 2 Gh. Asachi Technical University, Iasi, Romania 3 Prof. Dr. Nicolae Oblu Emergency Clinical Hospital, Iasi, Romania Abstract Complex fractures of the proximal tibia are difficult to treat. Minimally invasive plate osteosynthesis (MIPO) has determined the result improvement while the angular stability plate type Less Invasive Stabilization System proximal lateral tibia (LISS-PLT) or Locked Compression plate (LCP-PLT) were specially created for this kind of fractures. The purpose of this study was to emphasize the design and biomechanical characteristics of these systems as well as to evaluate the results following the treatment of the complex fractures on the proximal tibia by MIPO with these plates with angular stability. The authors emphasize the design of the plate, the concept of the internal fixator and the importance of the aiming device for percutaneous insertion. There were investigated 8 fractures of the proximal tibia in 8 patients, with a mean age of 39.5 years. Fractures were classified according to AO/ASIF in 2 type A3, 2 type C1, 2 type C2 and 2 type C3). There were three open fractures (1 type I and 2 type II) according to Gustilo. In all 8 cases we have performed minimally invasive plate osteosynthesis, using a LISS-PLT system in 5 cases or a LCP-PLT in 3 cases. All fractures healed after a mean time of 13 weeks and the knee mobility was considered as good (mean flexion of 105 ). Due to major biomechanical and biological advantages, the authors consider that, despite the high prices, the internal fixator type LISS-PLT or LCP-PLT represent the ideal implants for the complex fractures of proximal tibia. Keywords LISS-PLT, proximal tibia fractures, internal fixator, aiming device, angular stability. I. INTRODUCTION Complex fractures of the proximal tibia represent severe lesions that raise treatment problems. In displaced or unstable complex fractures (with/without articular involvement) the main indication is represented by the plate osteosynthesis [1]. The incidence of tegumentary necrosis, nonunions and infections is increased especially for the extended external and medial approach. These complications induce a decrease of the local blood flow due to excessive deperiostation and fragment devitalization. The disadvantages of the external placed plates determined authors as Krettek [2] to introduce MIPPO (minimally invasive percutaneous plate osteosynthesis) technique by medial approach. The main advantages are represented by the ease of molding technique and the subcutaneous placement, without deperiostation or blood flow limitations [3]. However, fixation with classic plates and screws has some limitations regarding immediate and secondary displacements as well as periosteal compression with blood flow reduction. The combination of four requirements for complex meta- and epiphyseal fractures (anatomical reduction, stable internal fixation, preservation of the blood supply and early active and painfree mobilization) has led to the development of a new generation of locked plates and instruments type LISS (Less Invasive Stabilization System). These systems were created mainly for MIPPO in distal femoral fractures [4] and recently for proximal tibia (LISS-PLT) [5,6] II. PURPOSE The purpose of this study is to emphasize the design and biomechanical characteristics of the locked plates type LISS-PLT and LCP-PLT (locked compression plate) as well as to evaluate the results following the treatment of the complex fractures on the proximal tibia by minimally invasive plate osteosynthesis with these plates with angular stability. III. MATERIAL AND METHODS The LISS-PLT plate has the properties of an internal fixator (screws with threaded head that are locked in the round threaded holed in the plate). This determines the stability increase and eliminates the risks of the secondary displacement, due to an accidental lag between the screw and the plate. There is no contact between the bone and the internal fixator, so the periosteal blood supply is preserved. (Fig. 1). This plate differs totally from the classic one where the screws are tightened to fix and compress the plate onto the bone; the stability is due to the friction between the plate and the bone (Fig. 1A).

5 2 Fig. 3 (A) LCP-PLT with combi-holes. (B) The concept of LCP with classical screw and locked screw. Fig. 1 Distribution differences for the biomechanical load for standard plates (A) by comparison to LISS (B) and bone-implant interface (adapted from Frigg R, Injury, 32, 2001) [10] By comparison with LISS-PLT with round threaded holes (Fig. 2) the introduction of Locked Compression Plates (LCP) with combi-hole [7] represented the next step in the evolution of the internal fixators by the possible placement of the classic screws (that brings the bone to the plate) or of the locked screws (in the threaded half of the hole) (fig.3). In order to increase the construct stability (bone-liss or LCP), a very complex pattern for the position and angulation of the proximal screws was developed in order to maximize the anchorage and purchase of the screws in proximal tibia (Fig.4). Fig. 4 (A-D) Position and angulation of the proximal screws in the LCP-PLT system. Fig. 2 LISS-PLT plate with round threaded holes. For optimal stability and for preserving the soft tissues, the internal fixator has to be placed very close to the bone. The plates are therefore preshaped (Fig. 5) and the midshaft is twisted to insure optimal position and fixation (Fig. 6).

3 Special instruments and insertion guides allow the plates to slide under the muscle in a percutaneous minimally invasive manner (Fig. 8). Fig.

$We have investigated 8 fractures of the proximal tibia in 8 patients, with a mean age of 39.5 years. Fractures were classified according to AO/ASIF in 2 type A3, 2 type C1, 2 type C2 and 2 type C3).$ $There were three open fractures (1 type I and 2 type II) according to Gustilo. In all 8 cases we have performed minimally invasive plate osteosynthesis, using a LISS-PLT system in 5 cases (Fig.$ The ideal anatomical location for LISS or for LCP-PLT is a more anterior placement on the anterolateral tibial wall, just posterior to the crest. (Fig. 7A).

The ideal anatomical location for LISS or for LCP-PLT is a more anterior placement on the anterolateral tibial wall, just posterior to the crest. (Fig. 7A).

$9 (A,B) Proximal tibia fracture C1/AO (C,D) MIPPO with LISS PLT. Fig.$

6 3 Special instruments and insertion guides allow the plates to slide under the muscle in a percutaneous minimally invasive manner (Fig. 8). Fig. 5 Molded LCP plate placement, at distance from tibial bone Fig. 8 (A) LISS-PLT with aiming device, made of carbon reinforced PEEK (B) LISS insertion through a limited curved approach, beneath the anterior tibial muscle. We have investigated 8 fractures of the proximal tibia in 8 patients, with a mean age of 39.5 years. Fractures were classified according to AO/ASIF in 2 type A3, 2 type C1, 2 type C2 and 2 type C3). There were three open fractures (1 type I and 2 type II) according to Gustilo. In all 8 cases we have performed minimally invasive plate osteosynthesis, using a LISS-PLT system in 5 cases (Fig. 9) or a LCP-PLT in 3 cases. Fig. 6 The twisted midshaft of the LCP-PLT. The ideal anatomical location for LISS or for LCP-PLT is a more anterior placement on the anterolateral tibial wall, just posterior to the crest. (Fig. 7A). Thus, the diaphyseal screws are angled slightly posteriorly in order to be directed toward the center of the tibial canal for optimal fixation into the bone (Fig. 7B) Fig. 9 (A,B) Proximal tibia fracture C1/AO (C,D) MIPPO with LISS PLT. Fig. 7 (A) Ideal anatomical location for LISS or for LCP-PLT (B) the diaphyseal screws, angled slightly posteriorly Superficial thread of the locked screws differs from the classic screws with sharp edges and does not cut through the bone substrate when a perpendicular load is applied. Moreover, the superficial thread insures a wider diameter of the core that allows a larger bending force. We have used either a curved incision or a strait incision from the Gerdy tubercle about 50 mm in distal direction. The anterior tibial muscle was detached 1 cm from the tibial ridge, allowing the LISS plate insertion between periosteum and bone. For complex intraarticular fractures we have performed first an indirect reduction and the bone defect was filled with bone substitute. The aiming device allowed the percutaneous insertion of the self-drilling, self-taping screws (Fig. 10). This was possible by using a special water-cooled drill sleeve which connects to a standard syringe and infu-

4 sion set for directing cooling sterile saline to the screw/bone interface and prevent heating. reestablish the length, axis and rotation during minimally invasive techniques [8] VI.

7 4 sion set for directing cooling sterile saline to the screw/bone interface and prevent heating. reestablish the length, axis and rotation during minimally invasive techniques [8] VI. CONCLUSIONS Even if our study is limited, our experience with MIPO with classic plates in proximal tibia and the present results with MIPPO with LISS-PLT and LCP-PLT allows us to consider the internal fixators as ideal for these difficult lesions. REFERENCES Fig. 10 The insertion of the locked screws in diaphysis using aiming device, drill sleeve and saline solution for preventing heating. IV. RESULTS All fractures healed after a mean time of 13 weeks without bone grafting. At the most recent follow-up, all patients were walking without crutches with a good knee mobility (mean knee flexion 105 ) V. DISCUSSIONS The system with angular stability type LISS-PLT and LCP-PLT have revolutionized MIPO techniques in proximal tibia fractures due to the biomechanical and biological advantages. Beside important benefits in direct high-energy injuries, the clinical and biomechanical studies have demonstrated that the features of LISS-PLT and LCP-PLT became particularly beneficial in osteoporotic bone, periprosthetic fractures and open fractures [4,5,6]. In the future, the real time photogrammetry and triangulation techniques by top-performance software will allow the trauma surgeon to obtain accurate images in order to 1. White R.R., Babikian G.M. (2000) Tibia: shaft, in AO Principles of Fractures Management, Thieme, Stuttgart Eds. Rüedi T.P., Murphy W.M., Dell Oca A.F., Holz U., Kellam J.F., Ochsner P.E., New York, Krettek C, Gerich F.T., Miclau T.H. (2001) A minimally invasive medial approach for proximal tibia, Injury, 2001, vol. 32, suppl. 1, Sirbu P., Mihaila R., Ghionoiu G., Bruja R., Asaftei R. (2006) Minimally invasive plate osteosynthesis (MIPO) in proximal and distal fractures of tibia. in Smrkolj Vl., (ed.) 7th European Trauma Congress, Ljubljana (Slovenia), May 14-17, Ed. Medimond Italia, pp , ISBN Frigg R., Appenzeller A, Christensen R., Frenk A, Gilbert S., Schavan R. The development of the distal femur. Less Invasive Stabilization System (LISS), Injury, Int. J. Care Injured, 2001, 32, Goesling T., Frenk A., Appenzeller A., Garapati R., Marti A., Krettek C., LISS PLT: Design, mechanical and biomechanical characteristics, Injury, Int. Care Injured, 2003, S-A11-S-A15 6. Sîrbu P., (2007) Osteosinteza minim invazivă cu plăci în fracturile femurului distal, Casa de Editură Venus, Iaşi 7. Frigg R., Frenk A., Haas N.P., Regazzoni P.- The Locking Compression Plate System. Dialogue (AO International), 2001,14, I, Ip David Orthopedic Traumatology A Resident s Guide; Springer Berlin-Heidelberg 2006 Use macro [author address] to enter the address of the corresponding author: Author: Paul Dan Sîrbu Institute: Gr.T.Popa University of Medicine and Pharmacy Iasi Street: 16, Universitatii City: Iasi Country: Romania pdsirbu@yahoo.com

LISS DF and LISS PLT. Less Invasive Stabilization Systems for Distal Femur and Proximal Lateral Tibia.

LISS DF and LISS PLT. Less Invasive Stabilization Systems for Distal Femur and Proximal Lateral Tibia. LISS DF and LISS PLT. Less Invasive Stabilization Systems for Distal Femur and Proximal Lateral Tibia.