Ribeirão Preto school of medicine locking nail: clinical experience in the femoral fractures treatment

Abstracts

Uma série de 103 casos de fraturas diafisárias complexas do fêmur foram tratadas com a haste intramedular bloqueada FMRP, no período de maio de 1987 a dezembro 1995. Das 103 fraturas, 67 eram cominutivas, 12 bifocais (segmentar), 4 espirais, 13 proximais e 21 distais, instáveis, rotacionalmente, da diáfise femoral. Do total dos casos, constatou-se 97 bloqueios estáticos e 6 dinâmicos. Dessas 97 estáticas, 7 foram dinamizadas durante a evolução. Clínica e radiográficamente a consolidação ocorreu em 97,09% dos casos, com média de 16,72 semanas e em 3 casos não houve consolidação. Houve 4 casos de infecção suspeita e 3 estabelecidas que foram debeladas e evoluíram para consolidação. Houve 81 casos de encurtamentos que variaram entre 0,5 a 4 cm com média de 1 cm. O encurtamento menor ou igual a 2 cm ocorreu em 73 casos. Desvio de alinhamento em qualquer plano acima de 10 º e igual a 15º foi observado em 8 pacientes. Houve 10 casos de deformidades rotacionais, porém nenhum caso acima de 10º. A incidência de infecção foi baixa e a de consolidação alta. A estabilização dessas fraturas complexas permitiu imediata mobilização do paciente, reabilitação precoce do membro e diminuição da permanência hospitalar, excetuando os politraumatizados. A haste FMRP permitiu o tratamento dessas fraturas sem o uso de intensificador de imagens e de fresas flexíveis com baixo custo operacional. Os resultados foram semelhantes aos obtidos com as hastes intramedulares bloqueadas que necessitam de aparelhagem técnica mais sofisticada, porém com vantagens para o paciente e a equipe cirúrgica.

ARTIGO ORIGINAL

Ribeirão Preto school of medicine locking nail: clinical experience in the femoral fractures treatment

Fernando Mendes Paschoal^I; Cleber Antonio Jansen Paccola^II

^IPós-Graduando do Deptº de Cirurgia, Ortopedia e Traumatologia, Faculdade de Medicina de Ribeirão Preto-USP

^IIProfessor Titular do Deptº de Cirurgia, Ortopedia e Traumatologia, Faculdade de Medicina de Ribeirão Preto-USP

SUMMARY

A series of 103 cases of complex femoral fracture were treated with FMRP (Faculdade de Medicina de Ribeirão Preto) nail. These fractures were treated from May 1987 until December 1995. From the 103 fractures, 67 were cominutive, 12 bifocal (segmental), 4 spiral, 13 proximal e 21 distal and unstable rotationaly. From the total of cases, 97 were statically locked and 6 dynamic. From these 97, only 7 were dynamised during evolution. Clinical and radiographic union had occurred in 97.09 per cent of cases with average of 16.72 weeks. In 3 cases the union did not occur with interlocking nail. There were 4 cases with suspected and 3 with established infection that were healed by the time of evolution. There were 81 cases of shortening that varied from 0.5 centimeter to 4 centimeters with an average of 1.0 centimeter. The shortening of less than and equal 2 centimeters occurred in 73 cases. The alignment distortion in any plane up from 10 degrees and equal to 15 degrees was observed in 8 patients. There were 10 cases of rotational deformities, but no case above 10 degrees. The infection incidence was low; and, the union incidence was high. The fracture stabilization had immediately allowed patient's mobilization, early rehabilitation and decreasing hospital stay, except in politrauma cases. The FMRP nail had allowed treating these kind of fractures without using any image intensifier or flexible reamers. Hence this method had turned the cost of treatment down. The outcomes were matching to those reported with intramedullary interlocking nailing which needs technical equipment more sophisticated.

INTRODUCTION

Comminutive fractures of the femoral diaphysis are one of the commonest in the orthopedic clinic. They are generally severe lesions frequently associated to deteriorarion of other organs and they can originate deformities and sequelae in the patients, as a function of immediate or late complications.

In the last decades, different intramedullary locking nail processes have been developed, combined to closed focus and with the insertion of screws that lock the bone to the nail. Using this method, static locking controls rotation and telescoping, possibilitating conversion for dynamic lock, when necessary.

Besides that, the intramedullary locking nailing, when adequately indicated and carried out with the appropriate technique, can be applied to other fractures, where type and localization hinder the use of the conventional nails.

Thus, according to the excellent clinical results presented in the literature^{(15,16,30,33,34)} using the locking nail and due to high cost and the need of a sophisticated hospital infra-structure, the development of new techniques which minimize costs and special equipments was considered important. A locking nail was developed from studies carried out in 1987 in the Ribeirão Preto College of Medicine, University of São Paulo. These studies included the clinical results from a master degree dissertation⁽²⁷⁾, a period in which 103 surgeries were effected, and the clinical results were analyzed. This paper presents the clinical experience as the conclusion of the investigation.

The material presented is the casuistic of femoral fractures operated on with the FMRP (Ribeirão Preto College of Medicine) locking nail and it is also relevant since the operations were carried out in the university hospital where the FMRP locking nail was developed. The osteosyntheses were carried out by the author, by orthopedists of the institution and by residents.

The technique and the instruments developed present the following characteristics: a) low cost; b) dispense the utilization of the image intensifier, special (orthopedic) table, and flexible reamers.

The aim of the study was to clinically evaluate the results of the treatment of 103 unstable femoral fractures using the FMRP intramedullary locking nail developed in Ribeirão Preto and to demonstrate the method efficiency as well as the advantages of the nail.

CASUISTIC AND METHODS

Casuistic

The patients operated on with the FMRP intramedullary nail, the inplants and the instruments used in the investigation are presented.

From May, 1987 to December, 1995, 111 pacientes were operated on with the FMRP intramedullary locking nail, in the "Hospital das Clínicas", Ribeirão Preto College of Medicine, University of São Paulo, and 11 in the UNICAMP "Hospital das Clínicas" (these data were discarded since the patients could not be found), summing up 122 patients with 124 diaphyseal femoral fractures. However, among the 111 patientes operated on in the Ribeirão Preto "Hospital das Clínicas", 10 were not included in this study since they did not show up for re-evaluation.

This study presents data from 103 fractures (101 patients) treated with the FMRP intramedullary locking nail. Among the 103 fractures (101 patients), 57 were right and 46 left, including 2 bilateral cases. Among these patients, 77 were male and 24 female. Concerning the fracture characteristics, 88 were closed and 15 open. Among the open fractures, according to Gustilo's et al.⁽¹³⁾classification, 6 (5.50%) were grade I; 9 (8.26%) were grade II. The fractures comminution was evaluated according to the AO classification criteria, and types B and C were more frequently observed. Most of the patients presented polytraumas with other associated fractures. All of them were operated on using FMRP intramedullary 1.22 mm and 2.0 mm wall thick nails ⁽³⁴⁾.

The ages of the patients ranged from 14 to 84 years, 30.47 years on average.

To classify the 103 fractures, a AO/ASF¹ group classification femur diagram was used, as Figure 1 presents according to Müller⁽²³⁾.

Thirteen fractures type A (12.62%), 61 type B (59.22%), 29 type C (28.16%) were registered and the FMRP locking nail indication was due to comminution of the fractures, in 67 patients (57.26%) because they were above the isthmus (proximal), in 12 (10.26%) because they were segmentar, and in 4 (3.42%) because they were spiral or long oblique.

Distribution of the fractures concerning localization was: 28 proximal (P), 5 proximal and median (P/M), 37 median (M), 3 median and distal (M/D), and 30 (distal).

Characteristics of the Nail

The nail and the special instruments were manufactured by Schobell Indústria Ltda. (Rio Claro/São Paulo/Brazil) and used in patients with complex femoral fractures. These patients were operated on with the intramedullary nail, whose characteristic was a conventional nail of Küntscher with 12 mm standard transversal diameter with clover leaf form modified and manufactured in 316 L stainless steel, with 12 perforations, two proximal holes in a 60º inclination, and ten distal holes, giving a freedom degree of 60º for the screws along the groove of the nail and its plan of symmetry, allowing orientation through the holes in a convergent or divergent direction and, thus, locking the nail in the medular canal in a lateral-lateral direction, as Figure 2 shows. The nail wall was 2.0 mm thick rather than 1.2 mm as the classic Küntscher nail.

The screws were similar to the AO/ASIF type, 4.5 mm, coiled only in their final 16 mm.

The instruments were specially developed according to Paschoal⁽²⁷⁾ to implant the FMRP locking nail.

Proximal locking is effected inserting two screws with the help of a proximal guide connected to the cranial end of the nail.

Distal locking is effected connecting the distal guide to the proximal guide, to determine the local where an orifice must be made in the femur lateral cortex, at the same distance of one of the more distal holes from the nail, at the height of the metaepiphyseal region. This orifice is the guide to remove a 1.5 cm diameter bone cylinder from the lateral cortical with the help of a special trefina. Additional curettage, at the bottom of the created defect, permits localization of the nail inside the medullary canal. Observing the nail inside the canal and the position of the proximal guide connected to the nail, a perforation of about 5 cm is made cranially to the defect, passing through both corticals and one of the nail orifices, where an adequately sized screw is placed. The bone cylinder is then placed in its original place, using a screw that passes through it, through the nail and the medial cortical perforation, effecting the additional distal locking and closing the defect.

In 41 patients, 1.2 mm wall thick nails and in 62 patients, 2.0 mm wall thick nails were used.

Method

The pacientes operated on with the FMRP locking nail were divided according to pre- and post-operatory care.

In the pre-operatory period, the patient were bed rested with approximately 10 to 15 kilograms skeleton traction in the tibial proximal region. In all cases, the so-called antitelescopable locking nail developed in the Ribeirão Preto College of Medicine and in the São Carlos School of Engineering, University of São Paulo ⁽²⁷⁾ was used.

In a first moment: verification of the clinical problem and confirmation of the indication for locking nailing (data which subside re-evaluation), by means of clinical and radiographic parameters. Then, awaiting surgery in Braun's ferule, the patient was submitted to tibial skeleton traction procedures starting with 10 kilos and increasing weight to 15 kilos after 1 to 2 days. Duration must be at least 5 days, to avoid excessive shortening, since the intra-operatory traction is only manual.

After surgery, sutures were removed by the 15^th day. Load on the limb was progressively increased according to the presence of callus in the follow-up radiographs.

The patients were placed on ferula or pillows, such as to maintain hip knee flexure near 90º to avoid adherence of the quadriceps in extension, with consequent loss of flexure. They remained in this position during almost all the first week, leaving it only for physiotherapy, which was instituted in the fourth day, with isometric contractions of the lower limb groups of muscles. The patients were encouraged to walk using walking aids permitting partial load up to 20 kilos, measured with a scale.

The patients were re-evaluated at least 12 months after surgery, in the orthopedics ambulatory, "Hospital das Clínicas", Ribeirão Preto College of Meldicine, when they were submitted to clinical examinations and X-rays. Evaluation of all the cases was done by the author, observing the Thöresen criteria⁽³⁰⁾.

All the patients were followed-up until fracture consolidation, with the exception of 3 whose fracture consolidated with another method of treatment.

To evaluate the fracture consolidation, clinical criteria as absence of pain in the fracture region and painless hip and knee mobility despite articular amplitude were observed. As radiographic criterion the formation of periostal callus simultaneous to the callus between the fragments. Radiographic control was effected immediately after surgery, after four weeks, after eight weeks and at periodic intervals until a minimum of 12 months. The patients were followed up to 12 months after surgery. Follow-up was effected in the ambulatory using clinical and radiographic parameters. The patients were asked in relation to complaints, in particular local pain; mobility of the hip and knee joints was determined; alignment and shortening of the lesioned lower limb were also determined. Concerning the radiographic aspect, bone alignment was observed as well as the formation of the callus around the fracture.

The results of the treatment were evaluated considering the X-rays analysis, the consolidation or not of the fractures and the presence or not of angular deviation; in the clinical examination, shortening and amplitude of the hip and knee movement were considered. The data were analyzed according to the Thöresen et al.⁽³⁰⁾ method, shown in Table 1.

To control bone consolidation radiographs were taken 8 and 16 weeks after surgery. When the radiographs taken in the 8^th week showed a satisfactory callus, total load was authorized.

Final radiographic control and complete re-evaluation were effected 12 months after surgery.

Consolidation of the fracture was defined as the period after surgery when total load in the limb was carried with no external support and radiological consolidation was observed⁽³⁴⁾

Consolidation delay was considered present if, radiographically, consolidation was not evidenced from 16 to 24 weeks after trauma⁽³⁴⁾.

Non-consolidation was defined as the presence of pain and movement in the fracture focus, with no radiographic evidence of progression of the consolidation 26 weeks after the lesion⁽³⁴⁾.

Surgical technique

The patients are placed in lateral decubitus on the contralateral side in the usual operating table. An incision of about 10 cm is made, starting just above the greater trochanter tip and descending aligned with the femur. The fascia lata is opened aligned with the incision.

The maximus and minimum gluteal muscle fibers are cut, giving access to the femoral neck junction with the greater trochanter. Two afastadores de Hohmann are placed in front and behind the neck base.

Punctioning, an orifice is made at middle distance between the Hohmann afastadores, in the neck-trochanter junction. The canal is opened with a long drill. The middle point of the neck-trochanter transition is perforated by means of a punction instrument and the canal is opened. The proximal fragment is successively widened with manual reamers till 12 mm.

The 9 mm reamer pushed by the motor is introduced followed by others, duly protecting the muscular fibers with a soft parts protector special for this purpose. Only the proximal fragment is reamed in this phase.

Passing of the guiding wire: an assistant supports the homolateral hemipelvis, making contraction in the antero-superior iliac spine, while another assistant produces moderate traction with the knee and the hip bent, as they were doing the test of the anterior gaveta. The guiding wire is introduced by the proximal perforation and tentatives are made in order that it passes to the inner distal medular canal, making maneuvers of angulation in the fracture, under traction as previously described. If reduction becomes difficult, an AO distractor can be used⁽²³⁾ as aiding element of reduction. Success in these tentatives is suggested by the attrition sensation in the inner part of the canal when the wire progresses and firmly stops as it meets the distal metaphysis spongy bone. On the contrary, if it is out of the distal canal, the progression stop is relatively "soft" and usually the wire protui in the skin.

If the closed passage becomes difficult a "miniaccess" is made, that is, a 3 cm transverse incision subscutaneous at the focus point. Three cm are longitudinally opened in the fascia lata, following romba dissection until the focus through the lateral vastus. Using one of the hands the guiding wire is advanced/retracted and with the other its is felt and orientated inside the distal canal opening.

Afterwards, impactation of the wire is effected in the distal spongy bone. The second guiding wire allows to estimate to which point the other has penetrated, placing it externally, side by side with the first.

Under traction, the nail lenght is estimated, and the tip of the second wire is placed in the tip of the greater trochanter. The lenght of the second wire that surpasses the first is the nail lenght that is entering the canal.

In all the extension of the isthmus the tubular L reamer is passed to guarantee that the canal has at least 12 mm in straight line and that the nail will not be detained.

The chosen nail is articulated in a special batedor and it is introduced in the limb under traction, with short rotational movements in the batedor handle. The nail must be delicately introduced till about 10 cm out of the wound. Angulation maneuvers in the fracture can facilitate the introduction. A 90º to 180º rotation in the nail using the batedor handle may resolve when progress is blocked.

The batedor is disarticulated and the proximal guide is connected to the nail after remotion of the guiding wire. In this point, the nail must have its longitudinal opening turned to the femur lateral cortical.

The nail is introduced until its end, so as the inferior part of the proximal guide touches the tip of the trochanter. It is very important to maintain traction during this phase, only liberating it after the first proximal screw is placed avoiding excessive shortening and penetration of the nail in the knee.

One must consider the force of gravity which frequently provokes valgus deviation in the fracture, specially when it is distal in the diaphysis. To avoid this, support is given (campos dobrados) to the medial face of the thigh before encraving the nail in the metaphyseal spongy bone.

An assistant maintains, then, the proximal guide firmly articulated in the nail, exerting light pressure on the proximal guide head, while traction is maintained.

The proximal drill protector is placed in the nearest perforation of the nail axle and the first perforation is effected.

The protector is withdrawn and the size of the screw is estimated with a special measurer. The proximal guide must not be withdrawn. It orientates concerning the perforation axle.

The first proximal screw is inserted with the help of a centralizing nipper and traction can be then liberated, since the nail is firm in the distal spongy bone and proximally fixed by the screw, with no more tendency to shortening.

The same steps are followed to place the second proximal screw, however, in the moment it will be placed, the interconnection element is placed instead, with the purpose of maintaining the proximal guide firmly coupled to the nail. In this moment, the assistant can liberate pressure on the proximal guide that maintains it articulated to the nail.

The distal guide is articulated in the proximal guide. Two marks are made on the skin, corresponding to the extremities of the nail distal perforated area, observing the calibration in the distal guide.

The distal guide is removed. Na incision is done in the lateral face of the thigh distal part, from one mark on the skin to the other. The fascia lata is opened aligned with the incision and the lateral vastus is elevated forward, with subperiostal dissection.

Ocasionally, it is necessary to cauterize the superior genicular vessels. Afastadores de Hohman are placed, exposing the lateral face of the distal femur.

The distal guide is again articulated in the proximal. The distal drill protector is placed as to be immediately proximal to the distal mark and to the nail chosen of the correspondent guide chosen nail. The protector is slightly fixed in the lateral cortical. Caution must be taken to avoid forcing the position imposed by the distal guide to the drill protector.

One perforation is made in the lateral cortical and the distal guide is removed. Afterwards, the special trefina centralizing piece is fixed and screwed in the perforation. With the machine, a "bone cork" (1.5 cm diameter cylinder) is then sawed using the trefina. Then, the spongy cortical distal bone cylinder is removed through the trefina guide which had been previously fixed.

Ocasionally, additional curettage is needed at the bottom of the cavity generated by the remotion of the "bone cork", to visualize the nail inside the femur.

When the nail is visualized after remotion of the "bone cork" in the alignment of the proximal guide, a perforation is made more proximally, inclined in relation to the nail long axle, and through one of its holes. An adequately sized screw is placed in this perforation.

With the mao livre technique, a perforation is made in the medial cortical, through the nail more central hole, in the removed "cork" resultant flaw. Using an adequate sized screw, the "cork" is again placed in its original position.

After passing the distal screws, a control radiograph is taken in two incidences, AP and profile.

The interconnection element is then removed and substituted by an adequate sized screw.

The graft taken out by the reamers is placed in the focus, through the mini-incision.

The wound is closed by planes, lefting aspiring drains in the proximal and distal wounds. The drains remain 24 hours.

Final radiographic control in the operating room is made since it is still possible to visualize the proximal portion in AP, the fracture focus and the distal segment in AP and profile.

In this study, the average time for the surgical procedure was approximately 72±43 minutes (minimum 47, maximum 169).

RESULTS

A hundred and three cases (101 patients) operated on with the FMRP intramedullary locking nail due to unstable diaphyseal femoral fractures were evaluated. Among them, 100 fractures (97.09%) consolidated after on average 16.72 weeks, with the exception of 3 cases that did not consolidate demanding another method of treatment to obtain bone union. Dynamization was necessary to obtain consolidation in 7 cases of delay.

Among the 100 fractures which were analyzed, 53 consolidated from 11 to 20 weeks. However, 21 and 26 fractures demanded, respectively, more than 20 weeks and less than 11 weeks, the minimum time for consolidation being 10 weeks and the maximum 48 weeks, on average 16.72. Figure 3 shows the evolution of 1 case treated with the FMRP intramedullary locking nail.

Mean follow-up was 27.18 months (minimum 12, maximum 76 months).

The presence of callus forming a bridge between the fragments was radiographically observed after 8 weeks on average.

Using the evaluation method according to Thörense et al.⁽³⁰⁾ it was observed that the general result registered 87% of excellent and good results.

The maximum post-operatory period was 6 years and 4 months, average 2 years and 4 months and minimum 12 months.

Walking with crutches and partial load on the operated on limb was allowed in the first days after surgery and after 8 weeks. Depending on the appearance callus in the X-rays and the clinical examination of the fracture stabilization, walking with total load was permitted.

Concerning capacity of march, 53 (51.5%) could walk continuously more than 5 km; 33 (32%) from 1 to 5 km; 10 (9.7%) from 100 to 1000 m, and 4 (3.9%) less than 100 m due to other locomotion problems and 3 (2.9%) due to non-analyzed cases.

Concerning pain, 55 (53.4%) had no pain; 41 (39.8%) had mild pain related to effort or change of weather; 4 (3.9%) moderate pain with effort, related to lesioned soft parts due to the trauma, and 3 (2.9%) were not analyzed.

Concerning the use of the lower limb, 80 (77.7%) had normal function, with no differences in relation to the healthy side; 14 (13.6%) ¾ of the function; 4 (3.9%) half of the normal function: 2 (1.9%) less than half of the normal function, and 3 (2.9%) were not analyzed.

Concerning resuming the activities exerted before the trauma, 70 (67.9%) resumed the same level of their original activities; 21 (20.4%) had mild restrictions; 5 (4.9%) moderate restrictions, 4 (3.9%) were disabled, presenting difficulty to walk, and 3 (2.9%) were not analyzed.

In the physician's opinion, 81 (78.6%) results were considered excellent, 15 (14.6%) good, 3 (2.9%) regular, 1 (0.97%) bad, and 3 (2.9%) were not analyzed.

Complications

Among the complications, 7 (6.8%) fractures treated by FMRP locking nailing presented delay in the consolidation, evolving to form callus after dynamization with withdrawal of the screws which locked the nail.

Shortening was frequently purposeful, in the cases of intense comminution, to ease the comminutive fractures consolidation when dynamic locking was used to facilitate consolidation. Mean shortening was 1.00 ± 0.99 cm (minimum 0.5 and maximum 4.0). This occurred in 81 patients, among which 35 had less malleolar spine lenght in the fractured side than in the contralateral side, from 0.6 to 1.5 cm. However, 23 patients presented less than 0.6 cm and other 23 more than 1.5 cm shortening,

Among the systemic complications, in 91, none; fat embolism in 4; pulmonary embolism in 2; pneumonia in 3; deep venous thrombosis (TVP) in 1, and respiratory insufficiency in 1.

Technical errors were observed intra-operatively.

Concerning the reduction quality, only 19 (14.71%) did not present any deviation; 81 (61.76%) presented shortening; 4 (2.94%) were valgus, 1 less than 5º and 3 equal to 10^º; 4 varus on average 7º (maximum 10º). In 2 cases in the femur distal 1/3; one in the proximal 1/3 and 2 in the middle 1/3 of the diaphysis; 4 (3.68%) varus one less than 5º, 4 equal to 10^º. This occurred in 5 patients with on average 6º (maximum 10º). Three of these occurred in the fracture proximal 1/3; in the other two, one in a patient operated on 33 days after the accident and the other with a distal 1/3 fracture, and 10 (45.38%) torsion deformities less than 15º (maximum 15º in only one case); 7 external torsions, and 3 internal torsions (more than one option). Varism was found in 4, valgism in 4 patients, and 5º antecurvatus in one patient. This last patient observing the intramedullary nail which has bent.

Rotation of the hip was normal in 93 (90.29%) patients. With small restrictions of no more than 10^º. There was mild torsional deviation in 10 cases, less than 4º to 10^º.

Concerning mobility of the knee, 93 cases did not present flexure-extension limitation, while 7 cases presented flexure limitation, respectively 0 to 110º and 0 to 40^º Only one case presented flexure limitation from 0 to 40^º.

In the post-operatory period, 7 cases of infection, 4 (6.8%) suspected and 3 (2.91%) established, were observed. Both were treated with drainage, débridement, continuous irrigation and antibioticotherapy with good evolution, with the exception of one case of grade II open fracture in which three days before the locking nail osteosynthesis, débridement and continuous irrigation were done, but even with these precautions, it evolved to a deep infection and after 12 months, when the nail was withdrawn and surgical cleaning was effected, re-fracture occurred and the external fixator was indicated as the option.

Among the 103 studied cases, 92% did not show local complications, while 10% showed the following complications: hematoma in 3, suspected infection with favorable evolution in 4, and established infection in 3; more than one patient presented more than one local complication.

Late complications were: in 7 (6.7%) cases, rupture and bending of the nails demanding substitution, in only 3 (2.91%) cases due to fall and a second motorcycle accident; 8 (7.77%) cases, rupture or bending of the screws evolving to consolidation with no need of change; in 6 (4.59%) cases, a re-osteosynthesis was necessary due to rupture and bending of the nail and screws. There were also 12 cases with the screws out of the orifices, but this had no implication related to consolidation. Figures ⁴ and ⁵ show the evolution of the patients treated with the FMRP intramedullary locking nail.

The status of the implants on re-evaluation was: no alteration in 82; removed in 19; dynamized in 7, and changed in 5.

DISCUSSION

The surgical technique used in this study⁽²⁷⁾ presents a method that provides stabilization of the fracture focus and allows not only its consolidation but also the mobilization of the patient, in general polytraumatized. It favors maximum preservation of the fractured fragments vascularization and facilitates bone callus formation, using simple material without sophistication. The easiness of the technique makes it accessible to most of the country services, with a low index of complications.

Winquist et al. e Wiss et al.^(33,34)reported their observations concerning pre-operatory traction. In the study developed by Paschoal⁽²⁷⁾, it was considered important mainly in what concerns the use of strong traction, using about 5 to 10 kilos in the tibial proximal region. It was also observed more easiness to reduce the fracture in the intra-operatory period, registering only a patient who needed 15 kilos to promote distraction of the fragments, since he presented great development of the quadriceps muscles.

Pre-operatory skeleton traction, in this study, was effected on average from 5 to 10 days. It is recommended as the initial treatment for femoral fractures including open fractures in non-polytraumatized patients. Brumback et al.⁽⁴⁾ and Winquist et al.⁽³³⁾ did not report such complications in their study, stating that, in the cases in which the patients are not polytraumatized and the femoral fractures are not considered isolated, the initial approach must be by means of strong skeleton traction. In spite of that, this study chose the pre-operatory traction to non-polytraumatized patients specially inpatients in the ITU who had their surgeries retarded making difficult the reduction of the fracture during operation because of the presence of the bone callus which had to be undone in order that a good reduction was obtained.

Considering the mini-access to the fracture, we praise Mattos et al.⁽²⁰⁾, Rodrigues & Ortiz⁽²⁸⁾ and Morelli et al. ⁽²¹⁾ findings. They state that mini-access does not interfere in the final result of the surgery, particularly concerning infection. In the studied case, the mini-access to the fracture, during the operation, possibilitated some advantages for a better performance of the surgeon. It was possible to determine shortenings, rotation alterations and, mainly, orientate the passage of the guiding wire in the distal fragment. Besides that, the non-utilization of the image intensifier during the operation avoided false interpretations, mainly the rotational, and exposition to X-rays.

In this study, 97.09% bone consolidation was obtained. This percentage is similar to the obtained by several authors with a consolidation rate from 96 to 100% ^{(2,9,14,17,30,34)}. Some authors as Böhler⁽³⁾ defend the closed technique, since less time for fracture consolidation would be necessary, and lower index of infection, earlier resuming of functions and shorter stay in hospital would be obtained.

Wu & Shih⁽³⁵⁾ reported 7% incidence of rotational alteration using intramedullary locking nailing.

In this study, 4 cases of valgus deviation were observed, with segmental (1), comminutive (1) and segmental (2) fractures, all types B and C. They presented valgism of 10º, 8º, 4º and 4º , respectively. Valgisms of the mentioned cases were not considered clinically and functionally significant.

Among the 103 diaphyseal femoral fractures, static internal fixation with FMRP intramedullary locking nailing was effected in 97 cases and dynamic in 6. Brumback et al.⁽⁴⁾ reported that approximately 10% of erroneous interpretations can occur when reading the pre-operatory radiographs and during operatory fluoroscopy. Brumback et al.⁽⁵⁾ stated that dynamization recommended initially by Wiss et al.⁽³⁴⁾ 6 weeks after static osteosynthesis is not an important factor in the consolidation process evolution and can cause risk of instability to the fractures⁽³⁰⁾. In this study, it apperead that dynamization contributed to the consolidation of the fractures since the nail, in 7 cases, was dynamized by screw withdrawal. These cases presented hyperthrophic characteristics of consolidation delay and lack of contact in the fracture focus. Among the 97 fractures which remained with static intramedullary locking nails, only 87 consolidated with the static FMRP nail until 12 months post-surgery, while 7 consolidated after dynamization by screw withdrawal and other 3 consolidated with another method of treatment.

It is believed that dynamization should be used only in the cases where the biologic factor is represented by bone callus deficiency. The experience promotes disagreement concerning Kempf et al.⁽¹⁵⁾ who suggest dynamization from 8 to 12 weeks while Brumback et al.⁽⁵⁾ prefer dynamization after 12 weeks to avoid shortening. Among the 94 static, seven patients were dynamized from 12 to 40 weeks; all of them were comminutive and segmental fractures type C and evolved till consolidation. Among the 103 fractures submitted to internal fixation with the intramedullary locking nail, 97 were static. In relation to dynamization, the option was 4 cases of fractures that presented rupture of the distal screws resulting in a consolidation delay, and in order that the fracture followed its normal consolidation it was necessary to choose the dynamization procedure.

An important fact concerning the FMRP nail utilization⁽²⁷⁾ is the non-availability of image intensifiers to aid during the operation in most of the national hospitals. That is one of the main reasons of the non-utilization of intramedullary locking nailing in Brazil. Thus, the utilization of the FMRP nailing is recommended to solve the difficulty to access high technology.

In the utilization of the image intensifiers one must consider: gonadal exposition levels; radiation on patients submitted to femoral fracture fixation surgery using intramedullary locking nails. The studies of Kwong et al ⁽¹⁹⁾ contribute to this argument since they observed that after a five-minute exposition, the radiation levels were statistically significant, justifying the use of gonadal protectors during surgery. Other authors studied alternative techniques aiming to reduce exposition to radiation through distal fixation with only one screw^(13,28,31).

The distal locking technique aided by the bone cylinder remotion, introduced in Brazil by Paccola & Paschoal⁽²⁶⁾ avoids the high cost of the investment in image intensifiers, since almost all existent locking nails in the market demanded the use of these intensifiers. Fernandes⁽¹⁰⁾ outlines that the advantages in using that instrument lead us to underestimate the radiation consequences for the patient being operated on. The staff is also unprotected since the effects produced by radiation propagation reach other operating rooms, not to mention the effect that the rays can cause to the surgical team with the so-called secondary irradiation. Nowadays, there exist at least two distinct methods to insert distal locking screws in the femur. One method uses placement of an external guide connected to the intramedullary nail, to localize the distal orifices, a principle we also base ourselves. The problem is that guide mobility and the nail deformation inside the canal disrupt the percutaneous placement of the screws⁽¹⁾ .

There also exist guides for percutaneous placement of the screws with radioscopy⁽³¹⁾ avoiding exposition of the hand to radiation, but this method is also difficult to perform⁽¹⁾.

Divergent placement of the distal screws to lock the nail possibilitates greater stability⁽²⁴⁾. Though the nail has a 12 mm fixed diameter, it is proven that it is mechanically more resistant when compared to the femoral AO-ASIF locking nails of the same diameter, also considering the resistance of the distal blocking first orifice⁽²⁵⁾.

Concerning the infection rate, suspected infections were 4 (3.88%) and established infections were 3 (2.91%). This percentual can be considered low as compared with the literature that analyzes under the point of view of the closed fracture focus⁽³⁾. Focusing the matter differently, Kovacs et al.⁽¹⁸⁾demonstrated that the infection incidence increased in the intramedullary treatment of femur fractures with open focus: with duration of stay in hospital before surgery, with multiple traumas associated to open fractures, and when two of these factors were associated. The 8 fractures were infected since they were open fractures treated under traction and débridement and continuous irrigation during 7 days.

The established infection rate was 2.91% and suspected infection 3.88%. All of them evolved to cure after treatment with drainage, continuous irrigation, débridement and showed consolidation with the nail.

There were other problems concerning bad alignment, similar to those mentioned by Johnson et al. ⁽¹⁴⁾; however, the knee range of movement was better in this series. Success was not so good as Kovacs' et al.⁽¹⁸⁾ in preventing shortenings less than 2.5 cm and bad rotation superior to 15^º. Fractures of the distal third of the femur are particularly prone to develop bad axial alignment. This was not observed by Johnson et al.⁽¹⁴⁾. In this study, 4 fractures with less and 4 with more varus equal to 15º resulted, as well as 10 femoral torsions below 10^º. In spite of the precautions with fracture reduction there was a mean shortening of 1.23 cm (minimum 0,5, maximum 4 cm). The cases which presented shortening and rotational deviation were, respectively, comminutives and spiral fractures according to Winquist & Hansen⁽³²⁾ though the locking nail is the best indication for these fractures.

Shortening of the femur from 0.5 to 4 cm was found in 81 cases. Shortening equal to 4 cm was also reported by Thörensen et al.⁽³⁰⁾ which presented results from 2.1 to 9 cm, while Wiss et al.⁽³⁴⁾from 1 to 2 cm. In this study only one fracture evolved to a 4 cm shortening. Bresides that, femur shortening from 0.5 to 3 cm was found in 80 fractures. The patient with 4 cm shortening evolved with almost 2 cm shortening besides the one observed in the immediate post-operatory.

Another resulting complication was the occurrence of varism in 4 cases during the post-operatory period grades 10, 8, 4 and 15, respectively spiral, comminutive, distal, and comminutive and proximal fractures. The causes of this complication are attributed to screws out of the hole, rupture or bending the screw or nail. The fractures consolidated and there were no clinical and esthetic implications in the result.

Concerning the possibility of re-fractures, reported in the treatment of the unstable femoral fractures, after withdrawal of the synthesis material and which occur in the treatment with plates and screws⁽³⁵⁾, this complication was observed in 1 case among 18. This complication was observed in one case when the nail was withdrawn, after 13 months, consolidated with history of infection treated with continuous irrigation and, at admission to hospital, débridement was carried out followed by surgical cleaning and continuous irrigation; 3 days after, locking nailing was indicated. After a clinical evolution of 12 months, infection was detected and nail withdrawal was indicated since the fracture was already consolidated. In order that the infection treatment continued we chose external fixation and three days after this procedure re-fracture occurred and was sustained with external fixator.

Concerning rupture of the implants, there were 6 cases in distal screws and all occurred most proximal to the fracture focus. Bucholz & Jones⁽⁸⁾ admitted that stress in the most cranial hole of the distal part is markedly increased in the femoral diaphysis distal fractures, and that fractures due to intramedullary nail fatigue may happen when this screw is inserted less than 5 cm far from the fracture focus. However, rupture of Küntscher intramedullary nail does not represent a serious clinical problem, but Zimmerman & Klasen⁽³⁶⁾ reported that it can be a greater risk with the nail locking system. Thus, it can be cosnsidered the probable cause of rupture of the screws in this study as reported by Bucholz & Jones⁽⁸⁾ and the second cause is that the fracture was distal and, thus, the screws were at a distance shorter than 5 cm.

Also concerning rupture of the implant material, one could observe that the greater number of rupture and bending of nails and screws occurred in those cases in which 1.22 mm wall thickness FMRP nail was used and also 4.5 mm screws totalling 7.77%. We can deduce that the 2.0 mm nails and the 16 mm distal screws are more resistant materials and that kind of complication is less observed, 6.8%.

One must emphasize that the higher index of complication due to nails and screws rupture and bending was 14.56% of the operated on cases with the FMRP locking nail. The higher number has occurred with the 1.2 mm thick nail (7.77%). This is also due to adjustment in the implant material and instruments resistance. It was also observed using the 2.9 mm thick nail, 6.8%. This variation may have occurred because it has been applied during the phases of ajustment of resistance, in spite that mechanical tests had been carried out evidencing more resistance of the material⁽²²⁾ .

During the study it was evidenced that ruptures and bendings can also have occurred due to proximity of the more distal cranial hole with the fracture focus^(6,7,9,11). It is outlined that the more distal cranial hole must be filled with screws, at a 5 cm distance between the focus and the first hole of the most distal cranial nail, in order that the nail resistance is not reduced, according to Fischer & Hamblen⁽¹¹⁾.

Finally, rupture of the implant material can occur due to the difficulty to accurately evaluate the consolidation process of these fractures, for instance: the exhuberant formation of bone callus that not always represents sufficient mechanical resistance for load support, favoring the excessive solicitation of the implant which had rupture and bending of the nail and screws as a consequence of failure in the radiographic evaluation which should have been more accurate in order to avoid that incident.

The utilization of the intramedullary locking fixation in the treatment of the comminutive diaphyseal fractures is advantageous when compared with other similar materials for osteosynthesis, because:

- Specialized material is not necessary other than the implant and instrumental material developed in the "Hospital das Clínicas", Ribeirão Preto College of Medicine.

- Orthopedic tables are not necessary, a great advantage when the patients are polytraumatized.

- Low index of complication.

- Functionally, excellent and good results were obtained in 97.09% of the reported cases.

- It emphasizes the importance of approaching the fractures through a miniaccess and the increasing preoccupation concerning the use of the image intensifier in operating rooms.

It was evidenced, also, that the FMRP locking nail can be used in complex diaphyseal fractures of the femur, possibilitating short stay in hospital, early march and lower costs. Since the intramedullary nail is the best option for the treatment of femoral fractures, from the anatomical, functional and physiological point of view, we conclude that the method attended to the clinical and biomechanical exigencies of femoral fractures, mainly comminutive, in which it was used. It is a feasible system and it is employed in Brazil.

REFERÊNCIAS

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• 32. Winquist, R. A.; Hansen, Jr., S. T. Comminuted fractures of the femoral shaft treated by intramedullary nailing. Orthop. Clin. North Am., v. 2, nº 3, p: 633-48, Jul, 1980.
• 33. Winquist, R. A.; Hansen, Jr., S. T.; Clawson, D. K. Closed intramedullary nailing of femoral fractures. J. Bone JointSurg.,v. 66-A, p: 529-39, 1984.
• 34. Wiss, D. A.; Fleming, C. H.; Matta, J. M.; Clark D. Comminuted and rotationally unstable fractures of the femur treated with an interlocking nail. Clin. Orthop., v. 212, p: 35-41, 1986.
• 35. Wu, C. C.; Shih, C. H. Effect of Dynamization of a Static Interlocking nail on fractures healing. Can. J. Surg., v. 36, nº 4, p:302-306 , 1993.
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1

AO/ASIF ( Arbeitsgemeinschaft für Osteosyntesefragen/ Association for the Study of Internal Fixation).

Publication Dates

• Publication in this collection
  28 June 2006
• Date of issue
  Dec 2000