COMPARATIVE ANALYSIS OF MODERN METHODS
International clinical practice of long bones lengthening (LBL) with intramedullary distraction devices at the modern stage of development of this orthopaedic area has rather few available set of medical technologies recognized by specialists: A.I.Bliskunov (Ukraine), [1, 15], A. Betz (Fitbon device, Ger-many , √ермани€) , J.-M. Guichet (Albizzia, device, France) [9, 16], S. Hankemeier (ISKD device, USA,) . Every known method has its own benefits and weak points. There are variations in distraction devices construction, implantation technologies and their application for LBL. These variations, respectively, determine the differences in clinical outcomes, in level of patients comfort during all lengthening program. Comparative analysis of methods and available results on already performed LBL provide the possibility to consider all the benefits and weak points more objectively.
Considering existent intramedullary distraction device (Fig. 1Ц5), one may note definite similarity in their outward appearance. In particular, every device consists of telescopic construction with two tubes. Advancing of one tube toward the other just determines lengthening effect (distraction).
Cinematic scheme of all intramedullary distraction devices operation (Fig. 1Ц5), has common similar series of consecutive operations that can be represented as "external effect Ц movement (force) > device mechanism > device internal tube advancing > - (distraction effect)". However, at this point all the similarities come to the end.
јппарат Ѕлискунова (”краина)
In scientistsТ opinion , this strain is enough to counteract muscular resistance during distraction. Although practical implication of the method in clinic has shown that muscular tension and regenerate formation Ц all are major obstacles that limit lengthening at big magnitudes. Maximal hip or shin lengthening magnitude with Fitbon device (one program of lengthening) does not exceed 4.5 Ц 5 cm. If it is necessary to achieve larger result of limb elongation repeated operations in 10-12 months (osteotomy in a zone of formed regenerate or device replacement) are performed and lengthening is continued. Next stage, generally, allows elongating limb segment length up to 3 cm .
Important Fitbon method characteristic that distinguishes it from other distraction methods is a way of force impact transmission to device mechanism. If all distraction devices are the УpureФ mechanics, the Fitbon method uses electromagnetic influence. It is clear that contact mechanical transmission of energy (force) is of high reliability. However, this is only for today. Scientific and technical developments undoubtedly will lead to new ways of noncontact energy transmission to device mechanism. In this sense Fitbon constructors made very important step that considerably broadened this development perspective in orthopedics.
However we should note several this method aspects, which in our opinion demand
more detailed study and possible improvement.
We should note that Bliskunov device (see. Fig. 1, 2) works with longer transmission
chain from external force to distraction effect.
Is this an advantage or drawback? In order to answer this question it is necessary
to "consider" all "positive" and "negative" aspects of such additional link as drive.
We may notice at once that УdriveФ presence in construction means additional surgical
manipulations for its implantation and removal (device switching off). We may also
state that the "drive" in Bliskunov device is additional link in construction,
because it is situated not inside the device. For УdriveФ positioning inside the
body "anatomic place" should be foreseen. At first glance the УdriveФ presence may
be classi-fied as the method drawback. However this view is eliminated if we consider
all functional advantages that Bliskunov method acquires due to this drive in
"Drive" (1) (see Fig. 1), and "drive" (3) (see Fig. 2) creates lifting jack effect,
where external force is smoothly transmitted to leader with step-up ration. On the
one hand, internal tube prolongation (5) (see Fig. 1) and (6) (see Fig. 2) goes
smoothly, without jerks, and on the other hand this tube protracts strictly by the
device axis (this means according to bone growth vector) without "additional",
"side", and rotational movements.
Thus, it is very important that Bliskunov device construction (see Fig. 1, 2) with
the "drive" (1) and (3) does not demand large external force to achieve lengthening
effect. This allows a patient actually during the whole lengthening program to
activate the device (to make LBL) independently (without help of doctor, assistant
and special equipment) outside medical institution, at home. Painlessness distraction
process and patient comfort during the device work are all evidences of sparing
regimen, caused by Bliskunov device construction.
"Drive" absence in јlbizzia devices (see Fig. 4), and ISKD devices (see Fig. 5) Ц
is an advantage. However, this link absence in kinematical system makes external
force transmission into distraction mechanism more direct and hard. External effect
in јlbizzia (see Fig. 4) and ISKD (see Fig. 5) devices Ц are rotational movements
of extremity segment. Doctor or assistant holds patient lower extremity by shin/foot
and make rotational movements (till characteristic click), trying to make the device
Such rotation leads to unscrewing of one device tube out from other with back
movement blocking, which provides for telescopic distraction effect. However, it
is necessary to note that dissected bone is situated on the device rod (apparatus),
which is in unstable condition (rotation/tubes unscrewing with further inner tube
prolongation). The device distraction effect is rotational movement of one apparatus
tube with respect to other. In other words, one device part with fixed in it
corresponding bone part is rotated with respect to other construction (the second
tube with bone part). As the result geometrical space parameters (volume parameters)
between bone margins in osteotomy zone are changed, there is regenerate tissue
screwing in space between bone margins, which is especially pronounced at the
beginning of distraction.
Every operation of ratchet gear in јlbizzia device (see Fig. 4) lengthens the system
by 0.07 mm (15 ratchet gear operations correspond to 1 mm of lengthening). Authors
[9, 16] note that distal fragment rotation shift (17) in respect to proximal (18)
by 20∞, which prevents regeneration, looses its negative effect as bone fragments
separate further. Experimental evidence shows  that their shifting during rod
mechanism turn becomes smaller in comparison with diastasis magnitude. However,
as bone fragments separate and paraosseous tissues are stretched the device mechanism
work becomes harder. In this connection the author  had to complete single-stage
hip lengthening in patients by several stages under general or transdural anesthetics
(such distraction steps number sometimes reached 30). At that the single-stage
lengthening was 4-10 mm. The author  described the case, when one patient could
tolerate only 13 such procedures, after which lengthening program was stopped. The
distraction process was complicated by the device fracture and false joint formation
ISKD device with identical construction (see Fig. 5) Ц the skeletal kinetic distractor
, also provides for distraction effect at distant fragment rotation (19) with
respect to proximal (20) (device movement in respect to external (15) and internal
(16) tubes) from 3 to 9∞. In authorsТ opinion , rotational oscillations are
physiological part of human walking process. Distraction 1 mm is achieved with
160 rotational extremity movements. Actual distraction magnitude is controlled by
special external manual monitor. Patients change daily distraction minimum 5 times
a day. If the distraction length is insignificant the lower extremity is rotated
under monitor control till desired length.
In the first and second cases there is necessity to carry out extremity rotational
movements under constant doctor control. At that general, transdural anesthetics
and other anesthetic methods are not excluded. Especially evident rotational
distraction drawbacks are during shin lengthening (see Fig. 4, 5). Here one of
the problems is УbehaviorФ of dissected fibula free ends during distraction device
activation. Danger of soft tissues and fibular nerve damage considerably hampers
shin lengthening by ISKD and јlbizzia methods, which is indirectly supported by
"poor" statistical data of general completed programs number of these segments
lengthening [16, 17].
Of special interest is bone regeneration in this distraction osteosynthesis conditions.
If we consider how axial instability in distraction movements affects bone regeneration
conditions, we may note that here periostal reaction is major component [9, 16, 17],
which is noticed both at diastasis level, and in adjacent bone fragments. At that
distraction regenerate Уgrowth zoneФ is absent.
Thus, "considering" all "pro et contra" of various distraction methods we
can not fail to notice that by today УdriveФ is rather Bliskunov device advantage.
Drawbacks of temporary (only for lengthening period) УdriveФ presence in the
device construction are compensated by exceeding benefits of its application.
Speaking about stability in regenerate zone we mean, at first place, strong bone
parts fixation as necessary condition for qualitative bone healing. However, as
for bone lengthening, the stability should be interpreted not only as good bone
fixation outside distraction process, but also clearly defined by axis advancing
and dosed bone fragments УseparationФ during distraction. Such stability is the
proper very important precondition for good final clinical result of long bones
In case of instability in osteotomy (future regenerate) zone the disturbances of
bone tissue reparation are possible. This is supported by experimental research
of V.I.Stetsul (1965)  of bones consolidation in long bones diaphysial
fractions after operative osteosynthesis by interstitial constructions. General
regularity was discovered: regenerate volume and its cartilage tissue content
progressively decrease with increase of bone fragments stability. In case of bone
fragments incomplete fixation (mobility in osteotomy zone) large bone-cartilage
or bone-fibrous regenerate is formed that leads to bone cross-section growth and
excessive periosteal callus as a bone УkeloidФ variety.
We can not disagree with J.-M. Guichet [9, 16], ј. Betz , and S. Hankemeier
 also in choosing osteotomy level. It is known  that long bone blood supply
normally is made predominantly through main nutritious artery that divides itself
in bone-marrow cavity into ascending and descending branches with predominance of
capillary net longitudinal-radial orientation. Osteotomy (21) (see Fig. 3), (22)
(see Fig. 4), (23) (see Fig. 5) at the level of upper margin of one-third or at
one-third of long bone diaphysis always damages main artery, and the necessary
bone-marrow cavity milling for distraction device even more damages intraosseous
blood vessels and leads to wide-spread bone microcirculatory disturbances. The
larger the device diameter, the more pronounced is traumatic effect on endosteum,
and, respectively, more prolonged is bone circulation restoration, which decreases
bone tissue reparative processes [5, 8].
Osteotomy level, proposed by the authors [9, 14, 16, 17] in our opinion is forced
choice. The point is that during technological channel milling there is danger
of cutter perforation of the anterior wall (on physiological curve top) of femur
(24) (Fig. 6а) in sagittal plane. At the point, where cutter (25) sets against
anterior bone wall the transverse bone osteotomy takes place (26) (Fig. 6б) with
the help of centro-medullary saw. Further milling of distal fragment is completed
from the physiological curve top (medium one-third of bone diaphysis), and the
bigger the bone curve, the more angle ? is increased to the front (27) between
proximal (28) and distal (29) fragments after intraosseous device implantation
(рис. 6б); that means load axis changing for lower extremity.
It is known that bone tissue reparation quality in distraction osteosynthesis
depends on several factors, namely:
Prof. A. I. Bliskunov already back in 1987 refused from stainless steel (12’18N9T)
in favor of titanium alloy, caused by cases of negative organism reaction Ц
metallosis Ц in some patients . Unique combination of titanium alloy properties,
namely, its mechanical strength, load resistance and light weight allowed decreasing
the device diameter considerably Ц from 15 to 12 mm, without compromising its
The table below summarizes basic characteristics of intraosseous distraction methods.
Morphological examinations  of tissue biopsy materials that surround intraosseous
device after its extraction testify that the material Ц titanium-vanadium alloy
(¬“-16), is biologically inert and does not produce pathological changes in bone
tissue and bone marrow.
With the purpose to determine possible foreign material effect on immunity we completed titanium alloy immune response for several parameters, namely:
We discovered that during the whole period of titanium device stay in human
organism neither quantita-tive nor functional characteristics of basic immunity
cells were changed significantly comparing to baseline. We also received
interesting results from patient, in whose body titanium alloy device rested for
5 years. Even in this case the patient organism did not develop aggressive
reaction to foreign body.
The obtained results testify on absence of negative titanium alloy effect on
immune system. These data are also consistent with studies results on immunity
factors determination in titanium carriers implantation in dentistry [6, 7].
The completed research allows concluding that internal distraction osteosynthesis
as orthopedic field gained much development during recent years. It is important
to note that implementation into clinical practice of УinternalФ bones lengthening
methods allowed us to approach significantly to keeping patient best interests,
the most important from them is distraction comfort and adequate clinical results.
Distraction devices multi-functionality, namely, intraosseous osteosynthesis as
long and adequate consolidating bone protection together with distraction effect
possibility that does not demand connection to external environment provided the
opportunity to minimize quantity of УsubmersibleФ into organism material (actually
it is, predominantly, only device corpus) with high efficiency.
Basing on completed research results we may name the main priorities on the way of methods improvement in intraosseous distraction: