|Year : 2022 | Volume
| Issue : 2 | Page : 110-114
Femoral lengthening using ilizarov ring fixator and slotted plate
Sujay Milind Kulkarni, Ruta M Kulkarni
Department of Orthopedic Surgery, PGI of Swasthiyog Pratishthan, Miraj, Maharashtra, India
|Date of Submission||23-Jun-2022|
|Date of Decision||04-Aug-2022|
|Date of Acceptance||26-Sep-2022|
|Date of Web Publication||29-Dec-2022|
Sujay Milind Kulkarni
PGI of Swasthiyog Pratishthan, Miraj, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Femoral lengthening is generally considered a cumbersome procedure due to the long fixator duration and complexity of the surgery. Lengthening over nail and lengthening over plate (LOP) have solved most of the problems but are associated with the risk of deep infection and plate prominence, respectively. We report a series of 14 cases with the use of a slotted plate to minimize both the problems. Materials and Methods: The study includes 14 patients, 8 females and 6 males, including four children. The average age of patients was 17.8 years, ranging from 7 years to 30 years. Femoral lengthening was performed with Ilizarov external fixator and slotted plate. Results: The target length ranged from 3 cm to 7 cm with an average of 4.6 cm. External fixator duration achieved ranged from 42 days to 92 days with a mean external fixator duration of 61.5 days. The mean external fixator index was 13.3 days/cm. We had no incidence of plate prominence or deep infection. We had four cases of knee stiffness, of which one needed surgery. All the patients had good quality regenerate and consolidation. Conclusion: The use of a slotted plate for LOP in femoral lengthening is a useful technique to minimize the incidence of plate prominence associated with LOP.
Keywords: External fixator index, femoral lengthening, Ilizarov, lengthening over plate, limb lengthening, slotted plate
|How to cite this article:|
Kulkarni SM, Kulkarni RM. Femoral lengthening using ilizarov ring fixator and slotted plate. J Limb Lengthen Reconstr 2022;8:110-4
| Introduction|| |
Femoral lengthening using Ilizarov fixator has been a time-tested method, with predictable results., The complications such as pin-tract infections, joint stiffness, and lack of patient compliance can be quite difficult to manage. Reducing the time of fixator can be one method to reduce these complications, but there is a risk of fracture of the regenerate after removal.
Techniques of lengthening over nail (LON) and lengthening over plate (LOP) have been devised to reduce the fixator duration as well as protect the regenerate after the removal. LON is very effective but can be associated with the risk of deep intramedullary infections. LOP minimizes the risk of this infection but carries the risk of the plate deviating off the track of the lengthening causing plate prominence and procurvatum deformity.
We report a study of 14 patients where the LOP technique was modified using a slotted plate instead of an Low Contact Dynamic Compression Plate (LCDCP). We believe it will minimize the risk of plate deviation and prominence and secondary deformity.
| Materials and Methods|| |
The study was approved by the institutional review board and was conducted after obtaining informed consent from the patients or their parents. In a retrospective review of 14 consecutive cases where the femoral lengthening procedure was performed by a single surgeon using an external fixator and slotted plate.
The cases included eight females and six males of average age of 17.8 years (range: 7–30 years). There were five cases of congenital short femur syndrome, four cases of postseptic physeal arrest leading to femoral shortening, four cases of posttraumatic shortening, and one case of congenital pseudoarthrosis of tibia (CPT). Except in the case of CPT, every other patient had femoral shortening and was thus advised femoral lengthening. The patient with CPT was advised of femoral lengthening due to extensive scarring of the tibia and was thus found unsuitable for tibial lengthening.
Ilizarov external fixator and a 4.5-mm slotted LCP with a 70-mm slot were used in all patients. The level of osteotomy was distal diaphysis in all patients. The duration of follow-up ranged from 12 months to 100 months with an average of 32.7 months. Patients were allowed to walk full weight bearing as pain permitted. On each follow-up, AP and lateral radiographs were obtained to monitor distraction, and pin tracts were checked. Wire tensioning was performed, and if necessary, local injection of antibiotic was done in the pin tracts.
The following parameters were then calculated:
- External fixator index – Number of days between external fixator application and its removal divided by the lengthening in centimeters, i.e. the external fixator duration for 1 cm lengthening
- Consolidation index – The number of days between external fixator application and three cortex regenerate consolidation divided by the lengthening achieved in centimeters.
The complications with the procedure were classified and documented using Paley's system, classifying them into problems, obstacles, and sequelae.
All patients were evaluated with detailed clinical examination and imaging in the form of a full-length leg radiograph (teleoroentgenogram) [Figure 1].
|Figure 1: A radiograph of both lower limbs shows left-sided femoral shortening|
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With the patient supine on a radiolucent table, the position of the plate and the planned site of corticotomy were confirmed under C-arm imaging. Following this, the incision was taken distal to the planned site and a 4.5-mm slotted LCP with a 70-mm slot (Pitkar, Pune, India) was slid extraperiosteally over the lateral surface of the bone. The plate was positioned such that there were at least three holes distal to the planned corticotomy after taking into account the proposed lengthening and three holes proximal to the corticotomy. The plate was then fixed distally using three locking head screws. Corticotomy was performed in the standard manner at the planned site such that it is just at the beginning of the slot. A cortical fully threaded screw was then inserted in the slot proximal to the corticotomy, preferably engaging both cortices.
An Ilizarov frame was then applied and fixed with one empty ring in the middle. The distal ring was fixed to the femur using at least two olive wires below the plate along with two Schanz pins posteromedial and posterolateral, and the proximal arch was fixed with two Schanz screws, and one Schanz screw as drop fixation. Clicking rods were used to connect the rings to aid lengthening [Figure 2].
|Figure 2: Immediate postoperative X-ray showing Ilizarov fixator with slotted plate and corticotomy. In this case, we have used unicortical screw in the slot|
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Patients were allowed to walk full weight bearing from the next day. Distraction was started from postoperative day 10 at the rate of 1 mm/day. The patients were put on a range of motion exercises for the knee.
Follow-up radiographs were taken every 4 weeks to monitor lengthening and the quality of regenerate [Figure 3].
|Figure 3: AP and lateral X-ray of the femur after distraction. Note the screw slides in the slot, keeping the bone fixed to the femur and on track of the lengthening. AP: Anteroposterior|
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On achieving the target length, the screws were inserted in at least three proximal holes of the plate. The external fixator was removed only after the plate had been secured proximally to prevent loss of length [Figure 4]. Weight bearing on the leg was not allowed until three cortex consolidation was seen on two orthogonal views, following which weight bearing was increased gradually and as per the patient's comfort. Radiographic evaluation was done to confirm that the target length was achieved [Figure 5].
|Figure 4: X-rays taken after the removal of the Ilizarov apparatus and insertion of locking screws proximal to the slot|
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| Results|| |
There were 14 patients included in the study, 8 females and 6 males. The average age of the patients was 17.8 years, ranging from 7 to 30 years [Table 1].
The mean lengthening was 4.6 cm (range: 3–7 cm). The mean external fixator duration was 61.57 days (range: 42–92 days). The mean external fixator index was 13.39 days/cm (range: 11.5–15.3), and the mean consolidation index was 29.82 days/cm (range: 22.4–41.8 days/cm).
There was one case of pin-tract infection which was resolved with local and systemic antibiotics. There were five cases of knee stiffness. Four cases of which resolved with physiotherapy.
In one case, knee stiffness failed to respond to physiotherapy. We had to perform a quadricepsplasty to gain range of motion.
In one patient, a case of congenital short femur syndrome, the limb lengthening procedure resulted in gradually increasing hip subluxation. This was treated by compression of the regenerate by 1cm, and a shelf procedure was performed to salvage this hip. The patient was asymptomatic.
We had no case of deep intramedullary infection or plate prominence in this study.
| Discussion|| |
Limb length discrepancy can be treated with nonoperative and operative methods The Ilizarov technique has undergone several evolutionary changes, but the basic principle of distraction osteogenesis remains the same.
Complications associated with Ilizarov include pin tract infections, knee stiffness, and joint contractures., To reduce the duration of the external fixator, many augmentative fixation methods have been tried, including intramedullary nails and plates.
Chaudhary demonstrated excellent results using intramedullary nails (LON) to reduce the fixator duration. However, they warn that care must be taken to prevent deep intramedullary infection and is certainly a risk with this procedure. Other studies have demonstrated the incidence of deep infection following this technique, but if managed aggressively, can significantly reduce the fixator duration and have a satisfactory outcome.,,
An alternative to the intramedullary nail is to use a plate. Kulkarni et al. described the use of an LCDCP to reduce the fixator duration (LOP). The plate is inserted at the time of the corticotomy, and screws are inserted on one side of the corticotomy. After the distraction is completed, the opposite side screws are inserted, and the fixator is removed. Chances of deep intramedullary infection are low. However, the complication of the plate being prominent and skewing away from the bone was reported.
This led to the use of a slotted plate, where one screw is inserted in a slot made in the plate, proximal to the osteotomy. The plate is fixed distal to the osteotomy by screws in the femoral condyle. This screw would then follow the direction of the distraction and prevent the plate from skewing away from the bone and prevent plate prominence. Once the distraction is complete, the rest of the locking screws are inserted, and the fixator is removed. We have used a 4.5 LCP instead of a DCP to provide even more stability to the construct.
The slot in the plate can be of varying lengths. For small target lengths, slots of 50mm or 60mm can be used. We recommend the use of 70-mm slots for any lengthening of more than 5 cm. We do not recommend the use of this plate in target lengths of more than 7 cm. The screw in the slot can engage both cortices.
In our case series, we have performed femoral lengthening in four cases of congenital short femur syndrome. Lengthening in this condition has been associated with high complication rates, approaching 50%. There was a complication of hip subluxation in one such case, where we had to do a shelf osteotomy. On investigation with a three-dimensional computed tomography scan, we found the acetabulum to be dysplastic. We plan to perform a corrective osteotomy for the acetabulum in the future. We recommend caution for the use of the technique in congenital short femur syndrome since the rate of complications is higher. Such cases should be managed preferably by experienced surgeons only.
Femoral lengthening is a technically demanding procedure. Lengthening over an intramedullary nail is even more so. LOP technique is simpler than LON since the placement of wires and screws need not be changed from the standard technique. As the middle ring is empty, this adds to the ease of the surgery.
Since the external fixator index has been brought down to an average of 13.39 days/cm, we feel it will be a lot more acceptable to patients and surgeons. It can be safely used in femoral as well as tibial lengthening procedures. More studies are required with a larger sample size and preferably randomized prospective studies comparing various techniques are warranted.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]