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Fixation of Femoral fracture in osteogenesis imperfecta with the Fassier-Duval telescopic IM system

    Overview

    Learn the Fixation of Femoral fracture in osteogenesis imperfecta with the Fassier-Duval telescopic IM system surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Fixation of Femoral fracture in osteogenesis imperfecta with the Fassier-Duval telescopic IM system surgical procedure.
    Osteogenasis Imperfecta (OI) is an inherited connective tissue disorder characterised by bone fragility and deformity. The majority of cases are due to defects in the genes responsible for type 1 collagen synthesis and assembly and its incidence is 1 in 15000 to 20000 live births. Extra osseous manifestations include joint hyper laxity, dental problems and blue sclera to the eyes.
    Although Sillence originally classified OI into 4 different types, in reality the disease is a spectrum from mild to severe. The most severe cases (type II) are generally an autosomal dominant inheritance and result in death in the perinatal period. Milder cases have normal life expectancy.
    Upper limb fractures are often treated conservatively. Lower limb fractures can be treated non operatively but frequently result in deformity which makes further fracture more likely. Bone remodelling may not occur before further fracture.
    Intramedullary stabilisation allows correction of deformity and strengthens the bone making refractor less likely. The femur is the most appropriate bone for stabilisation although tibial rodding has also become very popular. A few centres advocate rodding of humerus and forearm although telescopic rods are not used in the forearm due to narrow dimension of the bone.
    Growing telescopic rods were introduced in the 1970’s. The first generation were Bailey Dubov. These were followed by the Sheffield nails and then in late 1990’s by the Fassier Duval (FD) nail. The advantage of the 3rd generation systems such as the FD nail is that the implants can be inserted entirely from the tip of the greater trochanter since the distal tip on the male rod is threaded. Second generation systems such as the Sheffield nail had a ‘T’ piece at the end of the male and female components. Insertion required an arthrotomy of the knee. A window was then created in the distal femur to insert the male end of the rod. The female component was inserted from the top of the bone and a further approach made to the middle of the bone to railroad the female rod over the male. The procedure was even more complex in the tibia where the ankle had to be disarticulated to pass the male component retrograde through the distal tibia.
    Although the classic indication for telescopic rods such as the FD nail is Osteogenesis Imperfecta, the same implants have also been used for other fragility disorders such as Congenital pseudarthrosis of tibia, Fibrous dysplasia, and cerebral palsy.

    Indications

    INDICATIONS
    Femoral fractures in otherwise healthy children age 5 years and older are usually managed with intra medullary stabilisation. In these children implants are usually removed once the fracture has united. Children with OI are likely to re-fracture so the implant is ideally retained permanently. Standard implants quickly become too small to support the bone in a rapidly growing child. Telescopic nailing systems anchor into the epiphysis at each end of the femur (distal femoral epiphysis and greater trochanter). As the child grows and the femur lengthens the aim is that the rod should elongate to provide stability to the whole bone. The suitability for FD nail is determined by the size of the childs bone. It would be unusual for a child with OI to have a wide enough femoral canal prior to age of 3 years.
    Most patients will have been diagnosed previously either due to multiple fractures or positive family history but for some this may be a first presentation. In such cases non-accidental injury should always be borne in mind as a differential diagnosis.
    SYMPTOMS & EXAMINATION
    Patients present acutely with fracture. They age at which they present will depend on the severity of their disease. Femoral fractures in more severely affected individuals often occur as the child starts to weight bear. In the case of OI fractures occur with minimal trauma. Intra medullary stabilisation is also indicated in bones with significant deformity due to previous united fractures.
    IMAGING
    Fractures are generally assessed with plain radiographs. Anteroposterior and lateral views are necessary. If there are doubts as to whether a rod will be compatible with the dimensions of the femoral canal a CT can may aid in determining best form of management. If NAI is being considered a skeletal survey may be indicated although care must be taken since old fractures (eg of ribs) may be present in both conditions. Wormian bones on the skull x ray are characteristic of OI.
    ALTERNATIVE OPERATIVE TREATMENT
    In older children a telescopic nail is not required. Standard treatment in adolescents would include TENS (titanium elastic nail) nails (Nancy Nails) or lateral entry rigid nailing systems (ALFN).
    Telescopic nails can also be used as an elective procedure in patients who are at high risk of recurrent fractures. This will tend to be OI patients with 2 or more previous fractures where the femur is often deformed. In the elective scenario the same implant is used but the technique is different. Rather than the approach described here (fracture site opened) the nail is inserted integrate from the greater trochanter. Percutaneous osteotomies are performed as necessary to allow passage of the straight nail down the femur.
    NON-OPERATIVE MANAGEMENT
    The smallest telescopic nail is 3.2mm in diameter. If the femur is too small to accomodate a nail of this size the standard management would be traction (usually gallows traction) followed by hip spica.
    The advent of bisphosphonates has reduced the frequency of long bone fractures in OI. Bisphosphonates act by inhibiting osteoclastic activity. They are usually given intravenously and are withheld for a few weeks post surgery as there is some evidence that they slow bone healing.
    CONTRAINDICATIONS
    Telescopic nailing is not possible if the femoral canal is too small to accommodate the smallest nail (3.2mm).

    Setup

    Surgery is performed under general anaesthetic. Femoral nerve block or caudal block is advisable. For unilateral cases group and save is sufficient but cross match is required if bilateral surgery occurs( It is not possible to use a tourniquet of course).
    Prophylactic antibiotics should be administered prior to commencing surgery.
    A surgical assistant is mandatory. Image intensifier is needed throughout the operation and should be advanced from the opposite side of the table to the surgical team.

    Operation – 1

    Pre operative anteroposterior radiograph showing fracture midshaft femur.
    The transverse fracture indicative of a bone that has failed under tensile stress.

    Lateral radiograph shows bowing of femur indicative of previous fracture.

    Position patient supine with radiolucent bolster behind effected hip.It is imperative to ensure that imaging of the entire femur from greater trochanter to knee joint is possible. It is much easier to move the limb than the image intensifier (II) which should be positioned in an AP plane. If a radiolucent bolster (1L bag of normal saline) is placed behind the buttock of the effected leg it is simple to obtain an AP image by externally rotating the limb.

    By internally rotating the limb a lateral view of the distal femur is obtained.

    A lateral view of the proximal segment can be achieved by placing the leg in frog lateral position.

    Prep leg free and apply drape to ensure access to buttock, the entrance point for the nail.
    The leg is draped free. Either alcoholic betadine or chlorhexidine is used. Proximally a ‘U’ drape allows access to the proximal femur. It is very important that there is good access to the buttock since this will be the entrance point for the nail.

    Image intensifier(II) approaches from opposite side of table and lateral view is obtained by moving limb rather than the II machine.The image intensifier approaches from the opposite side of the operating table and the level of the fracture is identified.

    A lateral approach is used to access the fracture site which may need to be extended proximally or distally if further osteotomies are required.The incision is centred over the fracture. In OI patients will often have suffered previous fractures and the femur will not be straight. Multiple osteotomies may be necessary to allow passage of the straight nail.

    Make a straight incision parallel to the femur over the lateral aspect of the leg.
    Dissection should continue to the deep fascia and iliotibial band which is cleared by blunt dissection of the fat.

    Deep fascia is incised longitudinally over vastus lateralis.The deep fascia of the iliotibial band is incised longitudinally. It is important to ensure that one is not too far posterior since this will result in opening up the posterior compartment and hamstrings.

    Vastus lateralis is elevated forwards off the intermuscular septum and identify perforating vessels.Perforating vessels run from the posterior compartment forwards through the intermuscular septum closely apposed to the femur. they will be seen deep under the vastus lying on the periosteum. There are 4 or 5 sets along the total length of the femur.
    If torn or divided they will bleed profusely and may retract. They should be sought and either ligated or coagulated.

    In the case of fracture the periosteum will already be torn. This should be carefully elevated off the bone fragments and Homan retractors placed anterior (behind vastus laterals) and posterior to the femur. Major nerves and vessels are posteromedial to the femur and should not be at risk.

    The PEGA nail tray includes cannulated reamers, guide wires, male order inserters, male rod cutter and a female driver.
    The female rod is cut with diamond saw cutter (eg Black Max).
    The rod pusher is essentially a guide wire with a black handle.

    The anatomy of the PEGA telescopic nail
    The male rod slots inside the female rod. These 2 components are inserted separately, male first and then female over male.
    The female rod has threads proximally (A) to engage into the greater trochanter and its shaft (B) is cut to the appropriate length.
    The distal shaft of the male rod (C) can be seen at the end of the female rod. The male rod has flanges that insert into the driver and a threaded tip (D) that engages into the distal epiphysis.

    Deliver the proximal fracture end into the wound and pass guide wire retrograde.The proximal segment should be prepared first. Deliver the end of the fractured bone into the wound so that the medullary canal can be accessed.
    A long K wire or guide wire (usually present on the set) is passed retrograde. The wire should be narrow (less than 1.6mm) since the smallest size hand reamers will not pass over larger K wires.

    It is imperative that reaming is done by hand. The torque generated by power reaming runs risk of shattering the brittle bone. Fassier Duval nail sizes start at 3.2mm and increase in 0.8mm increments up to 6.4mm. Corresponding cannulated reamers are 0.25mm wider than the nail.

    Pass cannulated hand reamers over the guide wire.Start with the smallest reamer and gradually increase in size. It is not necessary to completely fill the canal with nail. Excessive reaming runs risk of fracture. Do not look for the characteristic ‘chatter’ of the reamer against the endosteal surface as one does with reaming of adult bones. The aim is to use the largest nail that fits comfortably in the canal.

    Check progress of reaming under II to determine whether an osteotomy of the bent femur is required.Reaming should be performed under II control. The femur will frequently be deformed from previous fractures and the reamer should only be advanced until it contacts the cortex on the convex side of the bone. This will determine the site of the next osteotomy (if required).

    Withdraw guide wire and reamer and perform osteotomy with saw or drill/osteotome.The osteotomy may be performed either with saw or drills and osteotomes. This should be done with care to avoid the bone shattering

    The bone ends may need to be shortened slightly since straightening a bent bone increase tension in the soft tissues. Using excessive force to reduce the fracture/osteotomy runs a risk of breaking the bone. Safeguard the segment of bone since this will be reinserted.

    Pass the guide wire down distal segment of femur.Once the osteotomised segment of bone has been removed it should be simple to access the distal segment.

    Pass guide wire as far as physis and then pass hand reamers sequentially over wire.A guide wire is loaded onto the hand held T handle and chuck. This is passed under II control aiming for the middle of the knee on AP and lateral planes.
    It is not necessary to pass the wire across the physis. Ream over this wire in the same manner as for the proximal segment taking care not to transgress the physis.

    Once the distal segment is prepared return to the proximal segment. Pass a guide wire retrograde so that it exits through the trochanter.

    Complete preparation of proximal segment by passing reamer retrograde through tip of trochanter. Pass guide wire through buttock.The aim is to exit through the centre of the greater trochanteric apophysis. Inevitably there will be some transgression of the piriform fossa. Avoid the temptation to exit to far laterally through the trochanter. There will be a risk of fracturing through the lateral wall and it will also be difficult to pass the nail.
    Once the trochanter has been reamed the guide wire is advanced retrograde through the buttock and skin. This point is typically 10cm proximal to the trochanter. The hip has to be flexed and adducted to improve the angle and minimise the distance that has to be transgressed by the guide wire.

    reassemble and reduce the femurWithdraw the guide wire through the buttock but leave the tip within the canal of the proximal femoral segment.
    Replace the isolated fragment/s of femur and “reconstruct the femur”. Hold the bone carefully with Hey Groves or similar bone holding forceps. It is easy to crush the bone.

    Operation – 2

    Advance the guide wire across the osteotomies as far as distal femoral physis.Once the femoral bone has been reconstructed advance the guide wire from proximal to distal across the fracture and osteotomised segments and into the distal fragment so that the tip is at the level of the distal femoral physis.
    At this point the length of male rod is calculated. Take a second wire that is the same length and pass this alongside the 1st wire (through the same wound in the buttock) until it touches the tip of the trochanter.

    Determine length of male rod by passing second guide wire to tip of greater trochanter under II.The next step is to determine the length of the male rod. Providing the 2 guidwires are the same length, by measuring the difference the length of nail can be calculated (ensure that tip of guide wire is at level of the physis).
    In addition to this one has to add the length of the threaded segment of the male rod which anchors distally in the epiphysis.

    Determine thread length from pre operative radiograph, these vary from 5mm to 15mm. There are ‘short’ and ‘long’ thread versions for each size of nail. The appropriate length is gauged from per operative x rays.
    Note the ‘flanges’ proximal to the threaded tip. These engage into slots on the introducer.
    Alternate sizes of nail have a small 1.2mm hole in the threads through which a small K wire can be passed to act as a ‘locking’ wire and stop the nail from backing out. This is rarely used in practice because it is so difficult to pass a wire across.

    Cut male rod to correct length.The male rod is cut with the specially designed cutter provided on the set. This gives a ‘clean’ cut which is imperative to allow smooth gliding of the components.

    Load male component onto introducer.The male component slots into the introducer. Be careful since there is no ‘lock’. If the introducer is pointed downwards the male rod will slide off it.
    Remove the guide wire and insert the male rod carefully.

    If it is difficult to access the entrance hole in the trochanter then the introducer (A) can be “railroaded” over the male rod (B). The male rod is passed retrograde through the proximal fragment so that its proximal end exits the buttock and the introducer then inserted over it.

    The male rod should be introduced slowly and carefully under II guidance.The male rod should be introduced slowly and carefully under II guidance using the appropriately sized introducer.


    Once the tip of the rod reaches the distal physis it is carefully screwed into the epiphysisOnce the tip of the rod reaches the distal physis it is carefully screwed into the epiphysis. Do not go too far since backing the rod out will make it loose.
    Aim for the centre of the epiphysis on AP and lateral views. All threads must be across the physis and in the epiphysis.

    Extreme care has to be taken when withdrawing the introducer since the male rod must not back out at the same timeExtreme care has to be taken when withdrawing the introducer since the male rod must not back out at the same time.
    There is a ‘pusher’ wire/rod that is inserted into the introducer so that pressure can be maintained on the male rod as the introducer is withdrawn. Use II to confirm that male rod is not backing out.

    The next step is to prepare the female rod. The length of the male rod is known. Subract the length of the threads plus an additional 1-2cm to accommodate the ‘flange’ on the male rod proximal to the threaded tip. Mark this with a pen.

    The length of the female rod is determined and the rod cut with diamond cutting disc.The female rod is cut with a diamond cutting disc since the rods are made of stainless steel and a standard bolt cutter would crush the lumen of the female rod. I use Black Max high speed cutter. It is critical to get a clean cut otherwise the rods will not ‘glide’. The rod gets hot so it is useful to slowly inject water or saline down the rod. Also, be careful since there are generally sparks generated by the diamond cutter.

    Ensure that the tip of the rod has no sharp edges. A mosquito forceps is useful to ensure the lumen is clear.

    The discarded segment of male rod can be used to test that the rods glide easily.The discarded segment of male rod can be used to test that the rods glide easily.

    The female rod is carefully inserted over the male. Use the II to ensure that the male rod is not being advanced into the knee.

    The female rod is advanced over the male rod until the proximal threads are fully engaged into the greater trochanterThe female rod is advanced until the proximal threads are fully engaged into the greater trochanter. If inadequately advanced there is a significant chance that the rod will back out.

    Check that the distal tip is still in the epiphysis and that the distal end of the female rod is not impinging on the threads or flange of the male rod.

    The wound is closed in layers.The wound is closed in layers. The vastus lateralis is allowed to fall back into position and the deep fascia repaired.

    Dissolvable subcuticular sutures are used for skin closure in the paediatric patient.

    Casts are necessary to control rotation. It is best to leave the foot free but pad around the leg, particularly the ankle, well. Collar and cuff material stops the lower edge rubbing.

    Keep the knee bent at 20-30 degrees

    A broomstick is applied to control rotation (both legs need to be in cast even if unilateral nailing). Do not apply with too much abduction since getting through doors can be difficult. Insufficient abduction and perineal hygiene is difficult.

    Fassier Duval nails do not have any rotational stability therefore a broomstick cast is applied with the knee slightly bent.Completed cast.

    Post operative AP and lateral radiographs are required to ensure that the alignment is satisfactory. The distal threads should be within the epiphysis and the proximal threads in the greater trochanter.
    This radiograph is taken at 6 weeks. Note that osteotomy is not completely united. Patient should be allowed to weight bear at this stage.

    The lateral X-ray confirms good re-alignment of the femur, and extra-articular position of the distal end of the implant.

    Post Operative

    Patients should have 2 post operative doses of prophylactic antibiotics. Blood transfusion is rarely necessary for unilateral surgery but may be necessary if 2 or more long bones have surgery at the same time.
    The patient is not allowed to weight bear until there are signs of callus. The Broomstick cast is retained for approximately 4 weeks and weight bearing commences under supervision of a physiotherapists at 5-6 weeks.

    Recommended Reading

    Our combined series (Birmingham and Bristol) has been presented and is in press. A series of 45 femoral FD nails had complications in 29 cases. One third of patients required revision for either periprosthetic fracture and bending of the rod or because the patient had outgrown the rod. Despite the threaded proximal end 11 patients required further surgery due to the female rod backing out. However, this is still less frequent than for the previous Sheffield system. Disengagement of the male threads from the distal epiphysis is more common in tibia FD nails but still occurred in 8 cases.
    Whilst complications remain common the results are as good as or better than previous 1st and 2nd generation systems.
    Overall we found approximately 65% 5 year survival which is similar to other authors (Azzam, J Pediatr Orthop 2018)

    Reference

    • orthoracle.com

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