History and evolution of minimally invasive plate osteosynthesis
In the first edition of “Technique of internal fixation of fractures” published in 1965 [ 1], the founding fathers of the AO Foundation laid down the following theoretical and practical principles of rigid internal fixation:
Anatomical reduction
Rigid fixation of fragments
Preservation of vascularization of the bone fragments
In their justification of these principles, the authors stated that direct healing of bone was a desirable clinical and radiological concept. It was also called “fracture union without visible callus formation”. They believed that any excess callus should be considered detrimental, regarded as a kind of “keloid” of the bone, indicating movement at the fracture site. Any radiologically visible callus formation during fracture healing after internal fixation was regarded as a warning that should initiate appropriate action. Union without radiologically visible callus, on the other hand, appeared to be the most desirable form of healing. The healing of a fracture without callus could be regarded as radiological evidence of continuous rigid fixation. These views were further supported by the experimental demonstration of direct bone healing by Schenk and Willenegger [ 2]. The trend, therefore, was for all fractures to be anatomically reduced and rigidly fixed, with direct bone healing without visible callus formation as the desired end result ( Fig 1-1 ). Subsequent editions of the “Manual of Internal Fixation: Techniques Recommended by the AO-ASIF Group” [ 3] restated the treatment principles as:
Anatomical reduction
Stable internal fixation
Preservation of blood supply
Early pain-free mobilization of muscles and joints adjacent to the fracture
The principles most attractive to surgeons were those of anatomical reduction and stable internal fixation, possible explanations being that these were the more visible and tangible of the principles as the results could be seen on x-ray. Furthermore, practical exercises at AO Courses were conducted using plastic bones stripped of soft tissues, thus giving the false impression that the soft tissues could be ignored. To be fair, in those cases of fractures treated by anatomical reduction and stable fixation with successful outcomes, and there were many, the results were impressive—patients were regaining pain-free mobility and function of their injured limbs shortly after surgery. “Fracture disease” soon became a thing of the past.
However, despite the inclusion of preservation of blood supply as one of the original treatment principles, and the emphasis on careful handling of soft tissue during surgery, these two elements of fracture management did not receive as much attention from the orthopaedic community. During this time, research and development were directed at improving the rigidity of internal fixation. The concepts of interfragmental compression with lag screws and compression plates, first with the articulating tension device and then with dynamic compression plates (DCPs), were introduced. However, it soon became apparent that rigid internal fixation of fractures did not always produce the desired end result. Instances of sepsis, sequestrum formation, delayed union or nonunion, and refractures were observed.
Research into these failures led to the discovery of the phenomenon of temporary porosis in the area of the footprint of the plate on bone. The cause of this was considerable damage to the periosteal circulation resulting at the interface between implant and bone ( Fig 1-2 ).
Studies using special undercut plates showed that the grooves in the plates reduced vascular damage and mitigated bone porosis. This led to the development of a special undercut plate, the limited contact dynamic compression plate (LC-DCP) (see also chapter 4 Implants, Fig 4-5 ).
Thus, the first moves away from mechanical stability of internal fixation toward biological internal fixation were made. Further evidence that absolute rigidity was not always necessary for fracture union came from the observation that fractures with flexible fixation also heal, albeit with callus formation. Such examples of flexible fixation or splinting came from intramedullary nails, external fixators, bridging, and wave plates. In fact, indirect healing often led to early and reliable solid bone union. The development of indirect methods of fracture reduction for diaphyseal fractures using the principle of ligamentotaxis led to the avoidance of further damage to the blood supply of the fracture fragments, which accompanied direct manipulation of the fracture ends. Furthermore, it was shown that internal fixation based only on reducing the mobility of the fracture fragments without contact between the bone fragments could result in solid healing. Thus, multifragmentary fractures fixed with bridging plates demonstrated high union rates without the need for bone grafting ( Fig 1-3 ). The explanation for this was based on the concept of interfragmentary strain.
The concept of interfragmentary strain states that fractures with a single, narrow gap are intolerant of even minute amounts of displacement due to deformation of repair tissues, while multifragmentary fractures can tolerate a greater degree of instability as the overall displacement is shared between many fracture gaps.
Similarly, the strain in fractures with a larger gap width was also reduced. It became apparent that anatomical reduction and rigid internal fixation were not necessary to achieve union in multifragmentary diaphyseal fractures. Fracture reduction in multifragmentary diaphyseal fractures became simpler and consisted mainly of regaining length, rotation, and axial alignment.
Thus the stage was set for the progression to more biological methods of fracture fixation, namely minimally invasive osteosynthesis (MIO).
MIO is not a new concept in orthopaedic surgery. Closed intramedullary nailing and percutaneous fixation of fractures using screws and K-wires had been performed with satisfactory results. Orthopaedic trauma surgery has traditionally attempted to minimize further trauma to the damaged area. With this consideration, minimally invasive fracture fixation was introduced with the external fixator by the French surgeon, Albin Lambotte, at the beginning of the 20th century, and also with the intramedullary nail by the German surgeon, Gerhard Küntscher, during World War II. Common to both techniques were minimal access to the bone through small skin incisions and an indirect reduction technique that did not involve direct manipulation of the fracture. The relative stability of both stabilization concepts resulted in indirect bone healing by callus formation. The appeal of this minimally invasive stabilization technique was not the small incisions but the biological advantages, such as minimal soft-tissue compromise. It enabled undisturbed fracture healing and fewer infection-related complications, compared to open reduction and internal fixation using cerclage wires and plates, during the early period of fracture fixation.
In multifragmented epiphyseal and metaphyseal fractures, in particular, where indirect reduction techniques using intramedullary fixation was not possible, an open and direct approach to the bone risks delayed bone healing and infection-related complications due to the additional operative trauma. Open reduction results in further devascularization of single fragments. In an attempt to obtain a biomechanically stable construct, the individual bone fragments were left untouched—the so-called “no-touch” technique—and their vascularity was maintained. The goal was not anatomical reduction but regaining length, rotation, and axial alignment. The healing pattern by secondary intention with callus formation enabled a more rapid progression to weight bearing and led to fewer secondary bone grafts and associated infections. In the late 1980s Mast and Ganz [ 4, 5] created the term “biological plating” to describe using indirect reduction techniques, mainly applying blade plates in the epiphysis/metaphysis as extramedullary splints ( Fig 1-4 ).
In 1996, Krettek et al [ 6] proposed a minimally invasive percutaneous plating osteosynthesis (MIPPO) for the distal femur using the dynamic condylar screw ( Fig 1-5 ). In a small clinical series of distal femoral fractures they showed the biological advantage of this technique which resulted in fewer infection-related complications, and fewer primary and secondary bone grafts compared to the traditional open-access surgery. The concept of anatomical reconstruction of the joint using an approach as large as necessary to obtain anatomical reconstruction, combined with a submuscular plating approach to limit additional trauma to the metaphyseal area, were important pillars for the evolution of the concept of minimally invasive plating. Several groups have since proven this concept by applying it to the epiphysis/metaphysis [ 7]; to the diaphysis, when a nail was not appropriate due to a narrow medullary canal [ 8]; an occupied femoral canal by a prosthesis; an open physis or due to physiological reasons in a polytraumatized patient [ 9]. Multifragmentary fractures fixed with bridging plates demonstrate high union rates without further need of bone grafts. In 2001 the first minimally invasive plate osteosynthesis (MIPO) approach using a helical bridge plate at the proximal humeral shaft was proposed by Fernández Dell’Oca [ 10]. In 2004 Livani and Belangero [8] showed the anatomical basis for and clinical application of an anterior bridging plate for the humeral shaft. Further anatomical studies by Apivatthakakul et al [ 11] gave rise to a widespread application of the MIPO technique for the humerus.
The evolution of submuscular plating was accelerated by the invention of internal fixators, eg, the point-contact fixator (PC-Fix), less invasive stabilization system (LISS), and locking compression plate (LCP). Locking head screws (LHSs) had the advantage of preserving the periosteal blood supply and they were easy to apply due to their self-drilling and self-tapping properties. Furthermore, the principle of the PC-Fix acting as an internal fixator caused no loss of primary reduction, when the plate was not anatomically shaped to the bone.
The introduction of the PC-Fix was the first step in the realization of the biological advantages of LHSs, which preserve both the periosteal and endosteal blood supplies. Furthermore, these self-drilling and self-tapping screws offered the advantage of simple handling. Following in the footsteps of the PC-Fix was the LISS, which is described in more detail in chapter 4 Implants, 2.3 Internal fixators. It was designed for application in the metaphyseal and epiphyseal areas, first of the distal femur (DF) ( Fig 1-6 ), and then of the proximal tibia. The LISS could be considered the first plate that was specifically designed and instrumented for insertion using a minimally invasive submuscular approach. It has a special insertion handle which facilitates the introduction of the implant submuscularly and, at the same time, acts as a drill guide for accurate insertion of the screws through separate small stab wounds. The LHSs which are used with this system also offer angular stability to the construct, helping to prevent secondary varus dislocation in the distal femur or the proximal tibia.
The next step which facilitated the widespread implementation of MIPO was the introduction of the LCP with its combination hole. These plates can be applied either as internal fixators using LHSs or as standard dynamic compression plates when using cortex screws. A multitude of new anatomical plates for different anatomical regions and a variety of specially designed reduction instruments have made MIPO a reliable and successful new alternative in orthopaedic trauma surgery.
This new technique with its biological advantages has some problems, including a steep learning curve and a potential for malunions due to the limited view using the C-arm for reduction control. Moreover, simple fracture patterns, due to inadequate reduction in distraction, or due to high strain when using a bridging plate concept treated by MIPO, may result in nonunion or delayed union. The concept of interfragmentary strain states that fractures with a single narrow gap are intolerant of minute amounts of displacement due to deformation of the repair tissue. Therefore in simple fracture patterns anatomical reduction with stable fixation to achieve absolute stability has been proposed using limited open access at the fracture site.
The technique of minimally invasive plating has been supported by the AO since its introduction by way of holding special MIO courses with the aim of teaching this technique in a safe and reproducible way. Since minimally invasive surgery is not determined by the length of the incisions but more by the reduction technique and soft-tissue handling, a definition of MIO includes the following recommendations:
Small soft-tissue windows are used to allow the insertion of implants and instruments remote from the fracture site.
Minimal additional trauma to the soft tissue and fractured fragments results from performing mainly indirect reduction. Direct reduction only when it is necessary to achieve fracture alignment.
Special instruments are designed to be used at the fracture site that cause minimal additional trauma.
In recent years several new and improved reduction instruments and implants have been developed which allow the direct reduction of a fracture by percutaneous means, for example, the collinear reduction clamp ( Fig 1-7 ), percutaneous manipulators, and MIPO cerclage passer.
Several clinical trials have proven the feasibility of the MIPO technique and its biological advantages with reduced rates of infections and less need for primary or secondary bone grafts [ 12– 15]. However, the need for secondary interventions due to nonunion or malalignment may be increased. Further clinical trials with higher levels of evidence are needed to continue to evaluate this promising technique which is likely to become another important element in the armamentarium of orthopaedic fracture treatment.
Further developments in the field of MIPO included the introduction of new types of LCP designed for use in specific anatomical regions, such as the proximal and distal humerus, distal femur, proximal and distal tibia ( Fig 1-8 ). At the same time, instruments that facilitate the surgical procedure are being introduced. Multicenter trials are being conducted to test the efficacy of these new methods, and research is ongoing. Although MIPO is a relatively new concept in fracture treatment, it is slowly gaining acceptance because the underlying principles are sound. Improved instruments and implants are being developed and, with ongoing research and clinical trials, MIPO has the potential of becoming one of the mainstays of fracture management in the years to come.
References
1. Müller ME, Allgöwer M, Willenegger H (1965) Technique of Internal Fixation of Fractures. Berlin Heidelberg: Springer-Verlag. 2. Schenk R, Willenegger H (1984) [On the histology of primary bone healing.] Langenbecks Arch Klin Chir Ver Dtsch Z Chir; 308:440–452. German. 3. Müller ME, Allgöwer M, Schneider R, et al (1991) Manual of internal fixation: Techniques recommended by the AO-ASIF Group. 3rd ed. Berlin Heidelberg: Springer Verlag. 4. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Technique in Fracture Surgery. 1st ed. Berlin Heidelberg: Springer-Verlag. 5. Kinast C, Bolhofner BR, Mast JW, et al (1989) Subtrochanteric fractures of the femur. Results of treatment with the 95 degrees condylar blade-plate. Clin Orthop Relat Res; (238):122–130. 6. Krettek C, Schandelmaier P, Tscherne H (1996) [Distal femoral fractures. Transarticular reconstruction, percutaneous plate osteosynthesis and retrograde nailing.] Unfallchirurg; 99:2–10. German. 7. Helfet DL, Shonnard PY, Levine D, et al (1997) Minimally invasive plate osteosynthesis of distal fractures of the tibia. Injury; 28 Suppl 1:A42–47; discussion A47–48. 8. Livani B, Belangero WD (2004) Bridging plate osteosynthesis of humeral shaft fractures. Injury; 35(6):587–595. 9. Pape HC (2008) Effects of changing strategies of fracture fixation on immunologic changes and systemic complications after multiple trauma: damage control orthopedic surgery. J Orthop Res; 26(11):1478–1484. 10. Fernández Dell’Oca AA (2002) The principle of helical implants. Unusual ideas worth considering. Injury; 33 Suppl 1:SA1–27. Review. 11. Apivatthakakul T, Arpornchayanon O, Bavornratanavech S (2005) Minimally invasive plate osteosynthesis (MIPO) of the humeral shaft fracture. Is it possible? A cadaveric study and preliminary report. Injury; 36(4):530–538. 12. Zlowodzki M, Bhandari M, Marek DJ, et al (2006) Operative treatment of acute distal femur fractures: systematic review of 2 comparative studies and 45 case series (1989 to 2005). J Orthop Trauma; 20(5):366–371. 13. Hasenboehler E, Rikli D, Babst R (2007) Locking compression plate with minimally invasive plate osteosynthesis in diaphyseal and distal tibial fracture: a retrospective study of 32 patients. Injury; 38(3):365–370. 14. Kregor PJ, Stannard J, Zlowodzki M, et al (2001) Distal femoral fracture fixation utilizing the Less Invasive Stabilization System (L.I.S.S.): the technique and early results. Injury; 32 Suppl 3:SC32–47. 15. Schütz M, Müller M, Regazzoni P, et al (2005) Use of the Less Invasive Stabilization System (LISS) in patients with distal femoral (AO33) fractures: a prospective multicenter study. Arch Orthop Trauma Surg; 125:102–108.Related posts:
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