Realignment and intramedullary rodding is the best surgical option for long bones deformities in osteogenesis imperfecta (OI). Plates and screws are contraindicated.1
Since 2001, the Fassier-Duval (FD) telescopic system has been used in the treatment of OI and congenital pseudarthrosis of the tibia and various skeletal dysplasias. This telescopic (growing) nail has the advantage over regular nails to have a lower revision rate, but is also more demanding technically.
The indications for rodding should be discussed during multidisciplinary OI clinics which is the ideal environment to manage these complex patients. These clinics allow for patients and families to receive evaluation by all providers (metabolic team, occupational therapy, physiotherapy, social worker, nutritionist, and pediatric orthopaedic surgeon) in a short period.
The discussion for the rodding depends on the following:
- The age of the patient.
- Ideally rodding is reserved for children who have reached walking age. The “signal” is when the child pulls up to stand. With the use of bisphosphonates, the gross motor development of OI children is faster.
- The deformities of the long bones.
- There is no scientific data to rely on for the maximum angulation that can be tolerated. It is generally accepted that beyond 20 degrees of angulation; it is difficult to protect long bones with braces, particularly femurs.
- The number of fractures.
- Two fractures of the same bone, the same year usually leads to rodding, but nondisplaced/incomplete fractures in minimally deformed bones can be treated conservatively.
- Surgery and bisphosphonates.
- Delaying surgery >48 hours after bisphosphonates administration is sufficient to ensure that no drug remains in the blood stream. This is important to avoid the drug “targeting” active bone sites such as osteotomies.
It is important to discuss with the family and define what their expectations are, and expose the risks and possible complications of rodding surgery.
Walking is the first important step in the life of OI patients; therefore, only lower extremity rodding will be discussed here.
When the 2 femurs and the 2 tibiae are deformed, the author prefers to rod 1 limb at a time, starting with the femur, and then the tibia is performed under tourniquet. The second leg is operated a week or 2 later. If one anticipates an easy percutaneous rodding, the 4 long bones can be done in the same setting. The advantages are obvious: 1 anesthesia, 1 postoperative pain, 1 hospital stay. If only the femurs or the tibiae need rodding, both can be done at the same time. Very rarely a patient will be booked for both lower extremity and upper extremity rodding at the same time (difficult installation, duration of surgery).
How many osteotomies will be necessary to straighten a bone? In most cases, 2 osteotomies are sufficient to correct severe deformities, sometimes 3. The placement of each osteotomy must be judiciously chosen to limit the number of osteotomies. This can be foreseen on preoperative radiographs, but fine tuning of osteotomy(ies) location is performed when the patient is asleep and ready for surgery (under C-arm guidance, careful analysis of the bone deformity(ies) is made before begin the surgery).
Open or Percutaneous Osteotomies?
For the femur, the absence of a medullary cavity on preoperative radiographs, and severe deformities (>60 degrees in which case, bone shortening will be necessary as the soft tissues will be under tension) should lead to choose open osteotomies. Percutaneous osteotomies are performed for patients with large bones, wide medullary canal and mild deformities. For the tibia, open osteotomies are the rule: the foot being in most cases in mild equinus before surgery, the correction of the angulation leads to a worsening of the equinus and the solution is bone shortening (which is preferred to Achilles tendon lengthening to avoid unnecessary weakening of the triceps surae).
Choice of Size of Rod
This can be done preoperatively on radiographs, but the surgeon must remember that OI bones deform overtime, the femur commonly anterolaterally due to the tether effect of medial hamstrings and the tibia deforms anteromedially due to the posterolateral tether of the triceps surae. Although the shaft angulates, the cross-section of the bone also changes and both femurs and tibiae take a “rib-shape” appearance. Therefore, on the lateral view of the bones, they look wide and the anticipated rod size is very optimistic, whereas looking at the anteroposterior (AP) view, the transverse diameter of the medullary canal is very small. For these reasons, I prefer to choose the implant size looking at the canal aspect after the osteotomy is performed. This has a corollary: all sizes of FD rods must be available in the operating room (OR) at the time of surgery, not just the rods chosen preoperatively.
INSTALLATION OF THE PATIENT IN THE OR
A radiolucent OR table is mandatory for such a surgery. The Jackson Table is a good option as it has no metal on the edges; but any OR table without lateral metallic reinforcement can be used.
The patient is positioned supine, with a saline bag under the buttock of the operated side. The patient is placed on the edge of the table (Fig. 1) for the following reasons:
- Before starting the surgery, the lower extremity to be operated is left hanging over the edge of the table, allowing a true AP radiographs of hip, to eliminate a “false” coxa vara.2
- During the surgery, the long reamers and male drivers, will be manipulated more easily outside of the table (eg, dropping the hand below the level of the table) than if the patient was on the middle of the OR table.
This semilateral position offers the great advantage of having access to a good AP view of the femur and a lateral when the hip of the operated side is flexed and adducted. Be sure, during the installation, that there is no obstacle for the use of the C-arm at the knee in lateral view (cautery plate/cable, catheter, or hand of the patient …). All the space on the opposite side of the pelvis must be free for good radiographic reading.
Before positioning the patient, the anesthesia team usually performs a caudal or epidural type of anesthesia for postoperative comfort. This “routine” procedure has improved significantly the postoperative care of our patients.
For more detailed description of this procedure, please refer to the referenced publications.3–5 The key steps will be summarized below.
Open osteotomies of the femur is performed through a classic posterolateral approach, lifting up the vastus lateralis. After the osteotomy is performed, the proximal fragment is reamed retrograde, aiming to the tip of the greater trochanter (GT). Reaming is “at mimima” as the idea is to support the bone and not to put the largest possible nail which will take the entire biomechanical load and prevent bone work. The reaming of the distal fragment, and additional osteotomy(ies) is performed, aiming to the middle of the distal femoral epiphysis, on both AP and lateral views. When reaming is done, to facilitate the introduction of the nail, a K-wire (male size) is pushed from the proximal osteotomy up into the buttock. The K-wire is found through a short incision and the male driver is pushed over the K-wire to the osteotomy site. The K-wire is then removed and replaced with the male nail which is locked in the driver. After reduction of the osteotomy (2 options if the reduction is difficult due to soft tissue tension: have the patient temporarily paralyzed, or shorten the bone), the male nail is pushed distally until it is close to the distal femoral growth plate. Check on both AP and lateral that the position of the nail is OK, and then (only then) screw it through the growth plate into the distal femoral epiphysis. The nail is often too anterior and an additional metaphyseal extension osteotomy can be performed percutaneously to ensure proper distal fixation. The female nail length is measured directly on the patient leg using a long K-wire and C-arm, and cut with the Midas Rex (Table 1).
The male driver is retrieved, taking care not to pull the male nail (a K-wire, same diameter is used to counter push the nail while pulling the driver, Fig. 2). The female nail is introduced and its’ length checked (Fig. 3) before screwing it into the nonossified GT. The threads of the female nail should not be screwed in the ossified metaphysis (in such a case, the GT will continue to grow proximally and the nail will apparently sink into the bone). The male nail can now be cut with the appropriate size male nail cutter, taking care not to bend the tip of the male nail above the female nail … or the rods will not telescope.
In case 2 osteotomies of the shaft are necessary, the K-wire used to facilitate the introduction of the male driver should be inserted from the most distal osteotomy up, allowing reduction of the proximal osteotomy under direct vision. The remaining of the procedure is the same.
Beware: most patients with deformed femurs present with a mild to moderate fixed flexion contracture of the hip flexors. Angulation of the C-arm beam is often necessary to check the proximal femur.
A short approach of the GT by splitting the gluteal muscles in the direction of their fibers allows to introduce a 1.6-mm K-wire through the tip of the GT until it reaches the apex of the deformity. Over the K-wire a 3.2-mm reamer is introduced and the bone reamed, leaving the reamer inside the bone. A short (2 to 3-mm long) incision is made at the apex of the deformity and using a straight small hemostat forceps, the fibers of the quadriceps are split, and a small osteotome is introduced. The bone is cut partially and by hand manipulation, the femur is progressively straightened (osteoclasis). Then the K-wire is pushed to the distal metaphysis (or the apex of the second deformity for a second osteotomy). The reaming is performed in the distal fragment and the reamer is removed. The K-wire is left inside the bone, and 1 hand of the operator is used to maintain traction of the osteotomized femur to keep the alignment. When the male nail is ready for introduction, the K-wire is removed and replaced with the nail, always keeping the femur in traction. When the nail is anchored distally, the introduction of the female nail follows the same steps as for open osteotomies.
After the femoral wounds are closed, a sterile tourniquet is applied (or a Hemaclear in small patients) and the osteotomy is performed (open) at the apex of the deformity. The choice of nail diameter is made depending on the medullary canal aspect. The distal fragment is reamed first. Then a medial parapatellar incision is made (3 to 4 cm) the fascia is cut and the prespinal area of the proximal tibia is identified (extra-articular). Using a “T” handle, a 2.0-mm K-wire (prebent ∼30 degrees in its distal third) is introduced through the middle of the epiphysis into the proximal metaphysis. The K-wire is removed and replaced with a 1.6-mm K-wire which is pushed down to the osteotomy side. The 1.6-mm K-wire is too flexible to be used to find the medullary canal of the tibia.
The K-wire is held with a Kocher forceps and the 3.2-mm reamer is introduced proximally. When the appropriate reaming is achieved, the male nail is introduced proximally and the osteotomy realigned (do not hesitate to correct in hyperextension 5 to 10 degrees). The nail is screwed (short threads) in the distal tibial epiphysis. The male nail is cut as flush as possible to the proximal tibial plateau (another option is to precut the male nail before insertion). The female nail is measured with the use of a long K-wire and C-arm (same as for the femur except that in the tibia the female threads must be completely inside the proximal epiphysis). It is then introduced and screwed in the proximal epiphysis (all threads should be within the epiphysis). After insertion of both nails, check that the male nail does not interfere with the knee extension. If it is the case, it must be shortened.
Before closing the wounds, a fasciotomy can be performed if it is deemed appropriate.
When the tibial wounds are closed, dressing and stockinette are applied on the entire lower extremity. A mold is taken for a brace (knee ankle foot orthosis for children who have never walked before surgery and ankle foot orthosis for children who walked before surgery). Then a long leg back slab is made for 3 weeks. Discharge is usually second day postoperation. At 3 weeks postoperation the patient is seen by the orthotist who removes the cast and fits the brace. The patient is seen for x-rays (Fig. 4) and a week of intensive physiotherapy (tilt table, pool therapy, then walker). As soon as the physiotherapist finds the quadriceps strong enough, the knee ankle foot orthosis is transformed into AFO’s.
No bisphosphonates are administered before 4 months postoperation; or clear radiologic healing of osteotomies. The medication acts in reducing the number of osteoclasts, and these cells are important for bone healing/remodeling.
The functional results of the FD rod in femurs in OI patients show that the improvement in ambulation, gross motor function, self-care, and mobility is beyond physiological expectations due to developmental growth.6
1. Fassier FR, Gdalevitch MShapiro JR, Byers PH, Glorieux FH, Sponseller PD. Implant considerations in long bones in osteogenesis imperfecta
. Osteogenesis Imperfecta
—A Translational Approach to Brittle Bone Disease. New York: Elsevier Inc.; 2014:421–426.
2. Fassier F, Zeeshan S, Aarabi M, et al. Results and complications of a surgical technique
for correction of coxa vara in children with osteopenic bones. J Pediatr Orthop. 2008;28:799–805.
3. Esposito PWFlynn JM, Wiesel SW. Multiple percutaneous osteotomies and Fassier-Duval telescoping nailing of long bones in osteogenesis imperfecta
. Operative Techniques in Pediatric Orthopaedics. Philadelphia: Lippincott Williams & Wilkins; 2011:259–269.
4. Fassier FRSabharwal S. Osteogenesis imperfecta
. Pediatric Lower Limb Deformities—Principles and Techniques of Management (Chapter 16). New York: Springer; 2016:255–266.
5. Fassier F, Paley D, Duval P. Fassier-Duval telescopic IM system, surgical techniques in Pegamedical.com. 2014. Available at: https://www.pegamedical.com
6. Ruck J, Dahan-Oliel N, Montpetit K, et al. Fassier-Duval femoral rodding in children with osteogenesis imperfecta
receiving bisphosphonates: functional outcomes at one year. J Child Orthop. 2011;5:217–224.
Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
osteogenesis imperfecta; telescopic rodding; surgical technique