Hospital do Servidor Público Estadual de São Paulo, São Paulo, SP, Brazila
The transtrochanteric fractures correspond to extracapsularfractures of the proximal femur included between the greaterand lesser trochanters.1,2Of the annual 250,000 proximalfemoral fractures in the U.S.A., 25% are transtrochanteric.3,4Each year, in developed countries this lesion affects one inevery 1000 people. It is estimated that in 2050 the incidencewill be three times higher3,5and the annual cost of US$ 8 bil-lion will be duplicated.3,6Thus, worldwide these fractures areconsidered as a major public health problem.1,2
These are the most frequent fractures, with higher associ-ated mortality rate (12-41% in the first six months),7and 90%of them, arising from low-energy trauma, occur in patientsolder than 65 years.8
Usually, the treatment is surgical. Only exceptionally theprocedure will be conservative in patients with comorbiditiesthat contraindicate anesthesia, surgery, or both.1,8,9It is essen-tial that the stability of the fracture be determined, so thatthe surgeon can properly choose the method to be employed.Unstable fractures are those lesions involving the posterior-medial cortex and that feature reverse trace or subtrochantericextension.1,8Recently, the critical importance of the lateralcortex in regional stability was recognized.10-13
In stable fractures, the implant of choice is the slid-ing hip screw (DHS); however, because of the biomechanicaladvantages of intramedullary location, cephalomedullaryimplants have been advocated for the treatment of unstablefractures.1,14-17
Both for DHS and for cephalomedullary pins, placingthe sliding screw in the correct position is crucial to thesuccess of osteosynthesis. The method of Baumgartner corre-sponds to the parameter of good positioning currently moreaccepted.1Anatomical characteristics of certain populationsand factors related to the experience of the surgeon wererelated to a placement not always considered "ideal" for theseimplants.18-20
In the evolution process of cephalomedullary pins, theanti-rotational device evolved in order to provide additionalstability to the system, both at the time of its implementa-tion and in maintaining the reduction until the consolidation.However, the presence of an anti-rotational device is relatedto early complications arising from its position, and later, likeas a "Z effect."1,21
The present study aimed to analyze the influence of the useof anti-rotational device in cephalomedullary pins used in ourinstitution in the average displacement of the sliding screwin its positioning along the central axis of the femoral neck.Furthermore, our study aims to determine the percentageof patients whose tip-apex distance was beyond the recom-mended measure, and the relation of minimum diameter offemoral neck for implant positioning.
Materials and methods
The study was submitted to and approved by the Ethics andResearch Committee of Hospital do Servidor Público Estadualde São Paulo (HSPE). All patients signed an informed consentto participate.
From January to December 2011, a case series comprisedof 58 patients admitted to the emergency room of the HSPEwith preoperative radiographic diagnosis of unstable proximalfemur fracture was prospectively analyzed. The participantswere evaluated for age, gender, and fracture classification.According to the classification of Tronzo,13fractures type III,variant III, IV and V (Fig. 1) were considered unstable. In theosteosynthesis, we employed the principle of relative stability,with the cephalomedullary tutor used in our institution. Thesurgical technique was common to all patients and consistedof an indirect reduction of the fracture and osteosynthesis in
Figura 1 - Classificac¸ão de Tronzo.
orthopedic table by the closed focus technique, with the aid offluoroscopy.
We used pins with a distal diameter of 10 or 12 mm and witha single proximal diameter of 17 mm, mediolateral angle of 6?and cervicodiaphyseal angle of 130?between the neck and theintramedullary nail screws. The choice of implant was takenafter preoperative planning, according to the cervicodiaphy-seal angle of the proximal end of the contralateral femur andthe diameter of the medullary diaphyseal region. All patientsreceived antithrombotic and antibiotic prophylaxis.
Two cases were excluded because, during the operation,it was decided not to use the anti-rotational device. Thesepatients were considered only in the assessment of gender,age and Tronzo's classification.
In the immediate post-operative period, plain digital radio-graphies (anteroposterior [AP] and profile [P] views) of thepelvis and of the hip ipsilateral to the osteosynthesis wereobtained, according to the standardization proposed by Pole-sello et al.22In AP view, the patient was positioned supinewith the legs in internal rotation of 15-20?and with the beamof X-rays directed at the midline just above the pubic symphy-sis. In Acelin's profile view, the patient was positioned supinewith 90?of flexion of the contralateral hip, with the X-ray tubeangled at 45?cranially in the horizontal plane, toward the rootof the affected thigh (Fig. 2).
With the use of filing and transmission system Impax®(version 6.3.1.7501, AGFA Health Care NV), the measures (inmillimeters) of the diameter of the femoral head at its great-est axis, diameter of the neck in its smaller thickness (AB),angle of reduction, distance between the center of the slidingscrew and the top edge of the anti-rotational device (ZX), anddistance from the center of the sliding screw to the inferiormargin of the neck (XB) were digitally obtained in the AP posi-tion. The central axis of the neck was determined using themidpoint of the smaller thickness of the femoral neck (AB).
The distance from the tip of the screw to the apex of thefemoral head was assessed in AP and P (Tip Apex Distance,TAD) views, according to Baumgartner and Solbert method.Fig. 3 shows schematically the points of reference used forthese measurements, and Fig. 4 demonstrates the use ofdigital tools of the Impax®program for obtaining the afore-mentioned measures.
The value of ZX (15 mm) is constant and supplied by themanufacturer. Such information was confirmed in an implantsample with the use of a universal caliper (Fig. 5). To ensurereliability of the data obtained, we applied as individual cor-rection factor for each measurement made the relation of themeasurement of ZX obtained on the digital radiography versusvalue provided by the manufacturer.Considering as ideal the positioning of the sliding screwon the central axis of the neck, we examined the feasibility ofthis positioning in our sample with the analysis of the mini-mum neck diameter required and its relation to the size of ZX.Then, we attributed the minimum distance of 2 mm from eachFig
eachFig. 2 - Standard positioning for AP and P radiographs.
Figura 3 - ZXBAB'Fig. 3 - Reference points for the proposed measures. AB:diameter of the femoral neck in its smaller thickness. AB:radius of the femoral neck. X: axis of sliding screw. Z: linetangent to the upper edge of the anti-rotational device. ZX:distance from the axis of the screw to the upper edge of theanti-rotational device.
Figura 5 - Fig. 5 - True measure of distance ZX, with universal caliper.
osseous margin and determined the equation: AB = (ZX + 2) 2.As the value of ZX corresponds to 15 mm, the minimum size ofthe femoral neck for such positioning is 34 mm. Then, we cal-culated the percentage of the sample in which the positioninghere considered as ideal could be obtained.We measured the average separation of the sliding screwin relation to the central axis of the neck in situations wherean optimum positioning cannot be achieved.The analyses of the quantitative variables were evalu-ated statistically with respect to the mean, median, standardFig
Fig. 4 - Use of Impax®for the taking of measures. (A) AP radiograph of the pelvis, as described. (B) Diameter of the neck andhead. (C) Angle of reduction. (D) TAD in AP. (E) TAD in PF. (F) Distance ZX.
deviation, minimum, and maximum. In the comparisonbetween the genders, we applied the nonparametric Wilcoxontest. The qualitative variables were evaluated for distributionof absolute and relative frequencies, and their associationswere tested by Pearson Chi-square test or Fisher exact test,when the approximation of the first test was not appropriate.The significance level used in these tests was 5%, and optionaltwo-tailed hypotheses always were considered.
Results
Of the 58 patients in the series, 42 (72.4%) were women and16 (27.6%) men. In the analysis of the age distribution, most ofthe study patients were between the eighth and ninth decadesof life, and there was no statistically significant difference inthe comparison between genders (Table 1).Regarding the classification of the fracture and accordingto Table 2, 33 (56.9%) patients were grouped as Tronzo III, six(10.4%) as Tronzo IV, and 19 (19.8%) as Tronzo V. The associativeanalysis between Tronzo's classification and gender revealedno statistically significant difference.With the help of standard X-rays, we obtained dataconcerning the angle of reduction achieved during the intra-operatory period and the implant positioning; no statisticalsignificance was demonstrated when comparing gender,according to Table 3.Regarding the TAD, it was observed that in 46 cases (82.15%)the values were smaller than 25 mm, thus being consideredideal.A comparison of neck and head diameter values of theselected patients showed statistically significant differencesbetween genders, which also occurred for the measure of Z X(Table 4).
Applying the correction factor for each individual measure-ment, values taken as real were obtained. These values areshown in Table 5.
Given the corrected diameter of the femoral neck,it was found that an ideal positioning would bepossible in 19 patients with CI (95%) = 21.8%; 47.8%(Table 6).
For those cases in which the position of the sliding screwcould not be ideal, the mean inferior separation value (XB)found with relation to the central axis was 4.06 (Table 7).
Discussion
The treatment of unstable transtrochanteric fractures withuse of cephalomedullary pins presents biomechanical advan-tages due to its intramedullary location, such as reducingthe bending moment, better rotational control, shortening,and collapse in varus.1,14-17Although controversial, thereare reports of superiority of cephalomedullary pins versusDHS in relation to early return to ambulation, reduced sur-gical time, and less blood loss.1,8,19Thus, at our institutioncephalomedullary pins are applied in the treatment of unsta-ble fractures.1
Regarding the epidemiological findings observed in thepresent study, there is a vast literature attesting the femalepredominance and an age close to 80 years in otherseries.1,9,18,21,23This reflects the decrease in bone mineral den-sity. We found no statistically significant difference betweenthe ages of male and female patients.
Although the pattern fracture of reverse obliquity (TronzoV or AO 31 A3) has been reported as the most frequent typein some case series of unstable fractures,9,24most studieshave described as the most prevalent types those classifiedas Tronzo III or IV (or AO 31 A2),1,18,25,26which agrees withour results. When comparing males and females, we foundno statistically significant differences in relation to fracturetype according to the classification of Tronzo.
According to Werner-Tutschku et al.,27the main predictorof the cutout is unsatisfactory initial reduction, especially invarus, besides favoring Trendelenburg gait.
We found a mean value of 130.5?for men (with a standarddeviation of 10.42) and 129.40?(9.81) for women, and thisassessment was not statistically significant. These findingsare similar to those found in another study with unstabletranstrochanteric fractures.1
There was a statistically significant difference in thecomparison between male and female genders in the mea-surements related to diameter of the head and neck. Whencomparing the bone structure of the neck in young andelderly subjects of Chinese and Caucasian origin, Wang et al.28showed that male subjects have larger diameters, that thisvalue tends to increase with age, being higher in popula-tions of white origin. According to Pu et al.,18as the Chinesepopulation is of lower stature than that of the European sub-jects, the length of the proximal femur and the diameter ofthe femoral neck are also smaller, which leads to the inappro-priate positioning of the cephalomedullary pin's spiral bladeused in the study, or to redundancy of the proximal end of thepin. In the utilization of the cephalomedullary pin used in ourservice, the minimum diameter for an optimal placement is34 mm, which corresponds to twice the Z X measure, takinginto account a thickness of cortical (top and bottom) of 4 mm.In our series, in only 19 patients (32.8%) the placement of thesliding screw could be performed in the situation regarded asideal by our methodology. Extrapolating the confidence inter-val for the Brazilian population, only in 21.8-47.8% of patientsin 95% of the time the implant could be placed optimally (i.e.,the center of the sliding screw located along the central axisof the neck).
According to Baumgaertner et al.,15the correct implantplacement occurs when the distance between the tip of thesliding screw and the femoral head center does not exceed25 mm after the sum of the values obtained on anteroposteriorand profile views (tip-apex index, or TAD 25 mm). This facili-tates the telescoping of the dynamic system of the implant andreduces the risk of cutout.9Although described for osteosyn-thesis with DHS, the method can be used to assess the correctpositioning of the cephalomedullary pins.1However, in pinswith two proximal fixation screws, there is difficulty in thepositioning of the sliding screw in the center of the femoralhead in the anteroposterior view. Thus, there is a greater ten-dency for the positioning of the sliding screw in a more inferiorlocation in the AP radiographic view, particularly in patientswith short femoral neck and head.21The location of the screwsin the profile position is not affected, since the screws are par-allel. In the osteosynthesis using the cephalomedullary pinin question, the mean displacement necessary for the intro-duction of the nail without violating the anti-rotational uppercortical neck was of 4.6 mm (i.e., the amount of downwarddisplacement of the system, in millimeters, from the axisof the femoral neck). To calculate the required displacementof the sliding screw relative the central axis of the neck insituations where this option is not possible, the following for-mula: = displacement required = 34 mm - neck size (AB) wasapplied.
Conclusion
Considering the mean diameter of the neck in our sample,the positioning on the central axis of the neck would not bepossible for the majority of the population.Considering the implant studied, the minimum size of theneck which allows positioning the central axis is 34 mm.
In situations where the positioning in the central axis isnot possible due to the minimal size of the neck, the down-ward displacement required can be calculated by the formula:displacement required = 34 - neck size (AB).
Conflicts of interestThe authors declare no conflicts of interest.
1. Borger RA, Leite FA, Araújo RP, Pereira TFN, Queiroz RD.
Avaliac¸ão prospectiva, radiográfica e funcional do tratamento
das fraturas trocantéricas instáveis do fêmur com haste
cefalomedular. Rev Bras Ortop. 2011;46(4):380-9.
2. Guimarães FAM, Lima RR, Souza AC, Livani B, Belangero WD.
Avaliac¸ão da qualidade de vida em pacientes idosos um ano
após o tratamento cirúrgico de fraturas transtrocanterianas
do fêmur. Rev Bras Ortop. 2011;46 Suppl 1:48-55.
3. Kyle RF. Fractures of the proximal part of the femur. J Bone
Joint Surg Am. 1994;76(6):924-50.
4. Fratura transtrocanteriana. Rev Assoc Med Bras.
2009;55:637-40. Disponível em:
5. Haidukewych GJ. Intertrochanteric fractures: ten tips to
improve results. J Bone Joint Surg Am. 2009;91(3):
712-9.
6. Cummings SR, Rubin SM, Black D. The future of hip fractures
in the United States Numbers, costs, and potential effects of
postmenopausal estrogen. Clin Orthop Relat Res.
1990;(252):163-6.
7. Russel TA. Intertrochanteric fractures. In: Bucholz RW,
Heckman JD, Court-Brown CM, Tornetta 3rd P, editors.
Rockwood and Green's fractures in adults. Philadelphia:
Lippincott Williams & Wilkins; 2010. p. 1597-640.
8. Kaplan K, Miyamoto R, Levine BR, Egol KA, Zuckerman JD.
Surgical management of hip fractures: an evidence-based
review of the literature II. Intertrochanteric fractures. J Am
Acad Orthop Surg. 2008;16(11):665-73.
9. Guimarães JAM, Guimarães ACA, Franco JS. Avaliac¸ão do
emprego da haste femoral curta na fratura trocantérica
instável do fêmur. Rev Bras Ortop. 2008;43(9):
406-17.
10. Kulkarni GL, Kulkarni M, Kulkarni S. Intertrochanteric
fractures. Indian J Orthop. 2006;40(1):16-23.
11. Gotfried Y. The lateral trochanteric wall. Clin Orthop Relat
Res. 2004;425:82-6.
12. Müller ME. Classification and international
AO-Documentation of femur fractures. Unfallheilkunde.
1980;83(5):251-9.
13. Tronzo RG. Symposium on fractures of the hip Special
considerations in management. Orthop Clin North Am.
1974;5(3):571-83.
14. Schipper IB, Steyerberg EW, Castelein RM, van der Heijden FH,
den Hoed PT, Kerver AJ, et al. Treatment of unstable
trochanteric fractures Randomised comparison of gamma
nail and the proximal femoral nail. J Bone Joint Surg Br.
2004;86(1):86-9.
15. Baumgaertner MR, Curtin SL, Lindskog DM. Intramedullary
versus extramedullary fixation for the treatment of
intertrochanteric hip fractures. Clin Orthop Related Res.
1998;(348):87-9.
16. Bridle SH, Patel AD, Bircher M, Calvert PT. Fixation of
intertrochanteric fractures of the femur. A randomized
prospective comparison of the gamma nail and the dynamic
hip screw. J Bone Joint Surg Br. 1991;73(2):330-4.
17. Schipper IB, Bresina S, Wahl D, Linke B, van Vugt AB,
Schneider E, et al. Biomechanical evaluation of the proximal
femoral nail. Clin Orthop Related Res. 2002;(405):277-86.
18. Pu JS, Liu L, Wang GL, Fang Y, Yang TF. Results of the proximal
femoral nail anti-rotation (PFNA) in elderly Chinese patients.
Int Orthop. 2009;33(5):1441-4.
19. Gadegone WM, Salphale YS. Short proximal femoral nail
fixation for trochanteric fractures. J Orthop Surg.
2010;18(1):39-44.
20. Heinert G, Parker MJ. Intramedullary osteosynthesis of
complex proximal femoral fractures with the Targon PF nail.
Injury. 2007;38(11):1294-9.
21. Kawatani Y, Nishida K, Anraku Y, Kunitabe K, Tsutsumi Y.
Clinical results of trochanteric fractures treated with the
Targon® proximal femur intramedullary nailing fixation
system. Injury. 201;42(Suppl 4):S22-7.
22. Polesello GC, Nakao TS, Queiroz MC, Daniachi D, Ricioli Junior
W, Guimaraes RP, et al. Proposta de padronizac¸ão do estudo
radiográfico do quadril e da pelve. Rev Bras Ortop.
2011;46(6):634-42.
23. Hungria Neto JO, Dias CR, Almeida JDB. Características
epidemiológicas e causas da fratura do terc¸o proximal
do fêmur em idosos. Rev Bras Ortop. 2011;46(6):660-7.
24. Ertürer RE, Sönmez MM, Sari S, Sec¸kin MF, Kara A, Öztürk I.
Intramedullary osteosynthesis of instable intertrochanteric
femur fractures with Proflim® nail in elderly patients. Acta
Orthop Traumatol Turc. 2010;46(2):107-12.
25. Chou DT, Taylor AM, Boulton C, Moran CG. Reverse oblique
intertrochanteric femoral fractures treated with the
intramedullary hip screw (IMHS). Injury. 2012;43(6):817-21.
26. Sahin S, Ertürer E, Öztürk I, Toker S, Sec¸kin F, Akman S.
Radiographic and functional results of osteosynthesis using
the proximal femoral nail antirotacional (PFNA) in the
treatment of unstable intertrochanteric femoral fractures.
Acta Orthop Traumatol Turc. 2010;44(2):127-34.
27. Werner-TutschkuW, Lajtai G, Schmiedhuber G, Lang T, Pirkl C,
Orthner E. Intra-and perioperative complications in the
stabilization of per-and subtrochanteric femoral fractures by
means of PFN. Unfallchirurg. 2002;105(10):881-5.br
28. Wang XF, Duan Y, Beck TJ, Seeman E. Varying contributions of
growth and ageing to racial and sex differences in femoral
neck structure in old age. Bone. 2005;36(6):978-86.
