A comparison of ef fi cacy of femoral and tibial fractures healing treated by static and dynamic intramedullary nails

Introduction: Intramedullary nailing is synthesis and consolidation of fracture fragments with the main goal to gain strength and permanent placement of the implants. Two techniques of intramedullary osteosynthesis are used: with dynamic or with static intramedullary nail. Dynamization include conversion of static nail by removing screws from the longest fragment. The aim of this study is to determine whether there is a difference in the speed and quality of healing of the type A and B fractures of the femur and tibia treated by static or dynamic intramedullary nails and to compare the results. Methods: The study was conducted on a total of 129 patients with closed fractures of the diaphysis of the femur and tibia type A and type B. Patients were divided into two groups, based on the applied operating method, static or dynamic intramedullary osteosynthesis. Results: The average number of weeks of healing femoral and tibial fractures was slightly in advantage of static intramedullary osteosynthesis, it was 17.08 weeks (SD=3.382). The average number of weeks of healing in 23 patients with fractures of the femur, treated by dynamic intramedullary osteosynthesis was 17.83 (SD=2.978). Conclusion: We can conclude that static intramedullary nailing osteosynthesis unable movements between fragments which directly stimulates bone formation and formation of minimal callus. Static intramedullary ostesinthesys resolve the problem of stabilizing the fracture, limb shortening and rotation of fragments. © 2012 All rights reserved


Introduction
In 1943 Bohler said that the installation of the nail in the bony canal is osteosynthesis that will be used in a future.Indication for osteosynthesis with intramedullary nail are fractures of the middle part of the long bones, most of the transverse and short oblique fractures, mostly of femur and tibia.Th is kind of stabilization has three main advantages : 1. Closed fractures can be treated in a closed technique, i.e. without additional exposure of fragments and damage of soft tissues.Circulation supply of the fragments remains fully sustained, and it's expected bone to heal in a similar way as by the non surgical treatment.Th e incidence of infection with this technique of osteosynthesis was signifi cantly reduced.2. Early stability and early function of extremities are achieved by axial (biomechanically optimal) use of implants, in favorable circumstances; the patient will be mobilized almost immediately aft er surgery.3. Th ird, which occurs regularly, are loosening nail into the medullary canal within a few months of use, thus encourages formation of biological callus growth and fracture crack that gradually accepts on greater force.Th e exception to this rule is statically embedded nail.Th e ideal goal in intramedullary nailing osteosynthesis is achieved when the nail is inserted with elasticity in both fragments.Th e greater the area of contact between the implant and the inner cortical means greater stability of the complex, and thus a better stability of the fractured fragments.Th e last model of intramedullary nail has the shape of three-leafed clover with longitudinal slit, and so far it is the optimal solution.Also in addition, it is possible ingrowth of new blood vessels from the medullary canal.It is especially signifi cant technological solutions -the top of the nail has a conical shape and breakthrough medullary canal, but also prevents notching the nail in the cortex during guidance through the medullary canal.At the other end is a separate opening in which the instrument hooks during the extraction of the intramedullary nails.Th ere are diff erent lengths and thicknesses of intramedullary nails, and its width is 0.9 to 1.0 mm.For each region there are special instruments.Intramedullary nailing osteosynthesis requires adequate technical conditions-instruments, x-rays in the room with one or two monitors, adequate operating table, experienced radiological technician, it is necessary that the patient is in the right position to do reposition of fractured fragments (1).Nowadays two techniques are mainly used, with static and with dynamic intramedullary nails: Static intramedullary nails use additional fi xation with screws, which are inserted into the proximal, distal, or at both ends of the nail.When the nail is stabilized with screws at each end of nail, then fi xation is static (2).Th is method avoids the problems losing of fi xation, stabilization, shortening, rotation that occur in plain intramedullary nail.Axially unstable fractures are best treated by static intramedullary nailing.Th e most common indication for the locking pin is comminuted fractures.Dynamic intramedullary nails are used in axially stable fractures of the bone and as well as in delayed bone healing process.Dynamic intramedullary nail has two screws, in the distal fragment and in the proximal fragment one screw which is axially movable by longitudinal slot in the implant.Dynamic intramedullary nail control bending and rotational deformity of the bones and implants, but the main advantage is to provide almost complete transfer of axial pressure on the bone fragments."Dynamization" is a process of converting static intramedullary osteosynthesis into dynamic intramedullary osteosynthesis.Dynamization re-quires removing farthest screw, 10-16 weeks aft er surgery.Earlier it was considered that the task of dynamization is to promote callus remodeling.Today's latest experimental studies and clinical studies do not consider dynamization as mandatory; some consider it detrimental to the healing time and frequent occurrence of limb shortening aft er dynamization.Majority believe that dynamization is necessary only in those cases where there is a permanent gap between the fragments, and the conversion from static to dynamic fi xation is rarely necessary, especially in fractures of the femur (3).Preoperative planning and measurement of implants should be performed on radiography of the bone that is not injured.TMD method is the best, cheapest and most accurate of all methods in determining nail length (the tibial tubercle-medial malleolar distance -distance between the highest points on the medial malleolus of tibia and tibial tubercle).Diameter of nail is assessed by measuring the tibia or femur on the tightest spot of medullary canal, which can be determined on lateral radiographs.Th ere are two types of intramedullary nails, rimmed and non rimmed type.Th ose who support non rimmed type of nails, highlight malefi cent eff ects such as fat embolism from bone marrow into the lungs.Th is eff ect is not clinically signifi cant in most patients; some authors suggest that the development of pulmonary complications may further connect with the associated chest injuries than with rimming of medullary canal.Potential advantages of non-rimmed technique over rimmed nail technique include shorter time of surgery, less blood loss and less disruption of endosteal blood supply in patients with severe closed injuries of soft tissues.Nowadays mostly it is preferred rimming technique and applications of rimmed type of nails, where there is no present signifi cant damage of soft tissues.Rimming type of nails enables application of stronger implants with larger diameter.Non rimmed nail insertion usually requires nails with a diameter of 8-10 mm, depending on the medullary canal diameter and cannot be used in patients with medullary canal narrower than 8 mm.Application of intramedullary nail in the short tubular bones of wrist and feet is a failure.Setting intramedullary nails in children contraindicate due to open epiphyseal growth plates.Th e aims of this study is to determine whether there is a diff erence in the speed and quality of healing of the simple fractures of the femur and tibia of type A and B treated by static or dynamic intramedullary osteosynthesis and to compare the results of healing of fractures of the femur and tibia treated by static or dynamic intramedullary osteosynthesis.

Methods
Th e study was conducted at the Clinic for Orthopaedic and Traumatology, Clical Center University Sarajevo from January 2004 to June 2009.Th e study was retrospective-prospective, manipulative, controlled.Th e study was conducted on a total of 129 patients with closed fractures of the diaphysis of the femur and tibia type A and type B, with different segments of bone, regardless of sex and age structure, with the exception of children under 14 years of age.Precisely there were 47 patients with femoral fractures and 82 patients with tibial fractures.Patients were divided into two groups, based on the applied operating method, static or dynamic intramedullary osteosynthesis: 1. Patients with fracture of the femur or tibia treated with static method of intramedullary nailing, where the static intramedullary nail fastened cross screws (3 or 4 screws) on both ends, and by that controls the axial and rotation instability and bending (24 patients with femoral fractures and 58 patients with tibial fractures) 2. Patients with fracture of the femur or tibia treated with dynamic method of intramedullary osteosynthesis (or patients whom had performed "dynamization"), which allows the complete axial pressure with control of bending and rotation.nailing.Of this number, 58 were treated with a static intramedullary nail with an average healing time of 13.55 weeks, and 24 treated with dynamic intramedullary nail with an average healing time of 15.17 weeks.Th e diff erence in the number of weeks of tibial fracture healing, in dependence of the nail (dynamic-static), it was signifi cant.Value of t-test is: t = 2.227, level of signifi cance of p <0.05.

Discussion
Intramedullary nail provide fragments stability and contributes to the process of osteogenesis.Biomechanical role of intramedullary nails is to keep the bone fragments in a good correlation, but also to prevent torsion and shear forces.It was considered that in a given moment should be provided an axial load transmission through the bone and fracture by the phenomenon of "dynamization", which accelerates osteogenesis by allowing micro-movements at the site of the fracture process, explanation was that the axial movements of fragments reduces fracture area, accelerates fracture callus maturation and remodeling of bone.Such recommendations for "dynamization" or converting static to dynamic intramedullary nailing for us surgeons are still unclear.It's constant dilemma, is the "dynamization" still needed, and when is the real indication and the optimal time for performing the same.Legacy of the 80's recommends to convert static into the dynamic form of intramedullary osteosynthesis in the period of 10-16 weeks, when the fi brous callus provide stability of the bone fragments, while other authors believe this procedure is unnecessary   or even harmful.Infections associated with implants for osteosynthesis according to the literature generally occur with prevalence of 5-10% (4).
On the other hand it can be said that perfect intramedullary nail has not yet been designed.Th e assumption of stable ostesinthesys is the strength and permanent position of the implant that is well tolerated by the tissues.Th e objective of such osteosynthesis is a direct angiogenic bone formation in conditions of absolute stability of the fragments and good vascularization.Th e fact is that healing of cortical bone of the femur and tibia and begins periosteal and endosteal.A review of available literature and published articles, we found limitations in the number and quality of studies published in longitudinal evaluations of available radiological and clinical methods for detailed analysis of the processes of bone healing (4).Also, we found that lack of consensus among orthopedic surgeons in terms of the defi nition of fracture healing.Without valid and reliable indicators of clinical and radiological signs of fracture healing, the interpretation of the fracture treatment success is diffi cult ( 5) Th e question is, which method is the most commonly used to evaluate the healing of long bones?Grigoryan and associates in their study tried to assess the quantitative and qualitative characteristics of bone healing using volumetric computerized tomography (CT) and to compare the results obtained by conventional radiological methods to assess healing of long bones (4) McClelland and associates in their study made a comparison between radiological assess fracture healing and strength measurements (stiff ness) of the layout (6).According to the method in which we are committed in this study, the author Corrales Morshed, Bhandaria & Miclaua shows the qualitative and quantitative fracture healing (3).Radiological Assessment of healing of fractures of the femur and tibia "cortical bridging" is based on data estimates healing each of the 4 cortical bone (anterior, posterior, medial and lateral) with a record of time until the appearance of callus, the time to the occurrence of mature callus fracture lines and loss of fracture line at diff erent stages fracture healing, performed by three independent examiners ( 6 ; 1 ; 7).In our study it was reported an average of 73.64% of identical responses and 25.58% of diff erent an-swers.Radiological assessment of fracture healing may be supplemented with bone densitometry and by measuring ultrasonic transmission.In certain cases of large callus due to the "fracture movements" it is possible to make additional mathematical processing generated callus summarized with clinical and radiological signs of fracture healing.What this research has defi nitely been sort out in relation to similar studies is that all fractures of the femur and tibia healed in a very short time, if they were perfectly operatively treated in an optimal time by an experienced operating team in strict compliance with the indications, and where the fragments diastasis were less than 0.2 mm.Necessary transformation to higher levels of care, with a well-trained surgical and monitoring team (anesthesiologist, instruments, support staff , operating rooms, a physiatrist and physiotherapist) and secured the technical conditions for the operation, make the optimum conditions for carry-ing out the method of osteosynthesis.Th is team has to be continuously available from the existing staff , with compulsory continuous training.Th e results of this study showed that adequacy of our suspicions of doctrinal conduction "of dynamization", and additional hospitalization for surgery, of "static screw" removal in the period of 10-16 weeks.Th e signifi cance is the same only in those cases where there is a bone fragment diastasis greater than 0.2 mm, and the conversion itself is rarely necessary in fractures of the femur.In the end, we would say that the study of treatment of fractures of the femur and tibia by static and dynamic intramedullary osteosynthesis showed all the good eff ects of early stabilization of fractures in relation to morbidity and length of hospitalization.Th e guarantee of success and quality of healing of fractures of the femur and tibia, treated by static and dynamic intramedullary osteosynthesis are proven low incidence of infection, high stability and strength of the fragments, the possibility of early mobilization of the patient with preservation of soft tissue and peripheral circulation.

Conclusions
Static intramedullary nailing unable movements between fragments which directly stimulates bone formation and formation of angiogenic minimal callus with sharp edges and a dense structure.Also static intramedullary ostesinthesys resolve the problem of stabilizing the fracture, limb shortening, rotation of bone fragments are the best recommendations for treatment are comminuted fractures.Dynamic intramedullary opsteosinethesys use of force on the fracture, causing bone resorption and thus looseness implants due to mechanical instability, which creates large (stimulus) callus with vague contours and turbulent structure.

FIGURE 2 .
FIGURE 2. The average number of weeks of tibial fracture healing presented by the type of nail.(A) Patients treated by static indramedullary osteosynthesis.(B) Patients treated by dynamic indramedullary osteosynthesis.(C) Total number of treated patients.

FIGURE 1 .
FIGURE 1.The average number of weeks of femoral fracture healing presented by the type of nail.(A) Patients treated by static indramedullary osteosynthesis.(B) Patients treated by dynamic indramedullary osteosynthesis.(C) Total number of treated patients.

TABLE 1 .
Clinical and radiographic signs of fracture healingResultsAccording to the results of clinical and radiological study conducted by three independent examiners, the average number of healing of fractures of the femur and tibia expressed in the weeks go slightly in advantage of static intramedullary osteosynthesis and it was 17.08 weeks with a standard deviation of 3.382.Th e average number of weeks of healing in 23 patients with fractures of the femur, treated by dynamic intramedullary osteosynthesis was 17.83, with a standard deviation of 2.978.Th e diff erence in the number of weeks of healing of fractures of the femur, depending on the type of nail (dynamic-static) was not statistically signifi cant.Value of t-test is: t = 0.897.According to the results, average number of weeks of bone healing of the tibial fractures were 14.02 in 82 patients treated with rimmed intramedullary

TABLE 2 .
The average number of weeks of femoral fracture healing by a nail.

TABLE 3 .
The average number of weeks of tibial fracture healing by the type of nail.