Tibial lengthening over intramedullary nails

Step 1: fibular osteotomy

The patient is supine on a radiolucent table. This is carried out under tourniquet control through a 2 cm to 3 cm lateral incision at the junction of the middle and distal third of the fibula through the interval between the soleus and peroneal muscles.

Step 2: intramedullary nail insertion and tibial osteotomy

In order to diminish the canal pressure, and thereby the risk of fat embolism during reaming of the intact tibia, it is important to vent the diaphysis.²¹ This is accomplished by drilling several holes that are 4.8 mm in diameter, at the level of the intended osteotomy. This has the additional benefit of allowing reaming to escape and function as prepositioned bone graft. The standard parapatellar tendon approach is used. The tibial canal is reamed over a guide wire to a total of 2.0 mm larger than the diameter of the nail (usually either 8.5 mm or 10 mm). The tourniquet should not be elevated during reaming, in order to allow better heat dissipation.

The level of the osteotomy is pre-planned on the radiograph to ensure that at least 5 cm of nail length are on the distal side of the distraction gap at the end of lengthening. The guide wire is withdrawn proximal to the planned osteotomy level. Through a 1 cm anterior skin incision, a 5 mm wide region of periosteum on the medial and lateral surfaces is elevated. A corticotomy is performed using either Ilizarov’s classical technique²² or the percutaneous drill hole technique.²³ Alternatively, a Gigli saw cut²⁴ can be performed. It is not recommended to use a Gigli saw in hard cortical diaphyseal bone, as it generates too much heat and leads to poor bone formation. The guide wire is re-inserted into the tibia, and the nail length is measured. The nail length should end about 2.5 cm above the ankle joint to allow distal fixation with two wires. The nail is inserted and locked proximally with two interlocking screws using the standard interlocking guides. If a nail with oblique proximal interlocking screws is used, the interlocking guide may sometimes be slightly rotated to capture the upper end of the fibula. Alternatively, the upper tibiofibular joint can be stabilised with a solid cortical screw, or with a tensioned transfixion wire. The distal tibial fibular syndesmosis is stabilised with a 4.5 mm solid cortical bone screw.

Step 3: application of the external fixator

With the nail in place and the osteotomy completed, an external fixator (Ilizarov circular external fixator or monolateral rail) is applied for lengthening. The pins and wires are carefully positioned so that they do not come into contact with the intramedullary nail. The space between the intramedullary nail and each pin/wire should be at least 2 mm (more space is preferred).

Ilizarov fixator - (Figs 1a to 1c) A frame consisting of three rings sized to allow two finger breadths of clearance circumferentially around the calf is preconstructed. Guided by the image intensifier, a 1.8 mm bayonet-tipped long transverse Ilizarov wire is inserted perpendicular to the nail, approximately 1 cm behind to the upper end of the nail and 15 mm to 20 mm below the knee joint. With the use of fluoroscopy, the wire on the lateral view is checked to make sure it is not in contact with the nail. The three-ring frame is suspended from this reference wire and tensioned to 130 kg. If properly aligned, the lengthening rods are parallel to the intramedullary rod. The distal ring should be 1 cm above the ankle joint. In the distal tibia, one transverse and one medial face tibial wire are inserted into the tibia and tensioned to 130 kg. Alternatively, one of the distal wires may be used to capture the fibula and tibia together, thus stabilising the syndesmosis. The frame should be adjusted in the sagittal plane before attaching these wires to ensure parallelism between the lengthening rods and the rod in the sagittal plane. Using a Rancho cube (Smith & Nephew, Memphis, Tennessee) and a 4.8 mm drill bit, a 6 mm half-pin is suspended off the upper ring by the proximal tibia. To make sure that the half-pin does not contact the nail, its position is checked with the image intensifier. Passing a 1.8 mm wire first and checking its position with the image intensifier is one way to ensure no contact. If the wire is at least 3 mm from the rod, a 4.8 mm cannulated drill bit followed by a 6 mm pin can be used. For additional stability, another half-pin may be added proximally. With no wires or pins, the middle ring acts to stabilise the construct by eliminating uninterrupted long threaded rods. The frame may be extended to the foot with the ankle positioned in neutral to prevent equinus from developing during lengthening.

Fig. 1

Illustrations showing lengthening over a nail using a circular fixator. (top left) The osteotomy has been made and stabilised by the intramedullary rod, which is locked proximally. The Ilizarov frame requires only minimal fixation: two wires distally and two wires proximally plus a half-pin. It is important to transfix the fibula at each end either with wires or cortical bone screws. After gradual lengthening, the rod has risen up to the diaphyseal region; (bottom left) a bird’s eye view of the proximal fixation. The wires (one of which captures the fibular head) and the half-pin are carefully inserted under control of the image intensifier to ensure that there is no contact between them and the intramedullary rod or its locking screws. Alternatively, the proximal and distal tibiofibular joints can be captured with independent bone screws. (right) The distal two interlocking screws are inserted to prevent shortening and the frame can be removed, leaving the rod as an internal stent, protecting the newly formed bone from bending, fracture, and deformation. Partial weight bearing is essential until there is complete consolidation. If the fibular regenerate bone is not healed at the time of frame removal, a cortical bone screw should be first inserted to stabilise the distal syndesmosis. Failure to do so may result in proximal migration of the distal fibula and disruption of the mortise. (Copyright 2015, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore).

Orthofix fixator (Orthofix, Inc., McKinney, Texas) - (Figs 2a to 2c) A monolateral external fixation system (Limb Reconstruction System, 400 mm lengthener) is applied. When inserting the most proximal and distal 6 mm half-pins in the posterior part of the tibia, use the wire/cannulated drill technique and make sure that the half pins are placed parallel to each other and perpendicular to the nail. When inserting the second proximal and second distal half-pins, choose an appropriate level based on the space available and the spacing of the Orthofix pin clamp. It is helpful to plan the placement of the four pins by pre-operatively checking lateral radiographs. The distal pin should not be in contact with the tibial fibular syndesmotic screw.

Fig. 2

Illustrations showing lengthening over a nail using a monolateral fixator. (top left) The nail is locked proximally. The proximal tibiofibular joint is captured by an independent bone screw. The distal tibiofibular joint is captured by a 4.5 mm cortical bone screw. During lengthening, the nail rises up. At the end of lengthening, the nail is locked distally. After frame removal, the newly formed bone matures under protection of the intramedullary rod; (bottom left) a bird’s eye view of the monolateral fixator slightly posterior to the intramedullary nail. The proximal fibula is transfixed with an independent screw; (right) a sagittal view of the tibial bone showing the position of the intramedullary nail in relation to the external fixator pins before lengthening has started (copyright 2015, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore).

Aftercare

The ankle is splinted in dorsiflexion with an orthotic that has Velcro straps to pull the foot up. The Velcro straps connect to the Ilizarov rings or to an arch that can be piggybacked onto the monolateral fixator. Distraction is begun at 0.25 mm four times per day, seven days post-operatively. Daily physical therapy to maintain knee and ankle ROM should begin one to two days after surgery. In addition to one hour of supervised physical therapy per day, the patient should undertake knee and ankle ROM exercises at home. Only touch-down weight bearing with two crutches is permitted during the distraction phase. Radiographs are obtained every ten to 14 days to monitor distraction. For delayed bone formation, the rate of distraction should be slowed to 0.75 mm per day, or 0.5 mm per day.

After the lengthening goal is achieved, the patient returns to the operating room for the distal locking screws to be inserted into the tibia and the external fixator is removed (Fig. 3). To prevent loss of length, it is important to lock the nail before removing the fixator. The distal tibial fibular syndesmotic screw must remain in place to prevent proximal migration of the distal fibula, as tension from the immature regenerate bone tends to pull it proximally. The patient must continue using two crutches and partial weight bearing until the newly forming bone is bridged on at least two sides. After two cortices are completely bridged, full weight bearing with crutches is permitted in unilateral cases and 50% weight-bearing in bilateral cases. In bilateral cases, full weight bearing without crutches is permitted once three intact cortices are seen. Hardware removal may be offered electively six to 12 months after complete healing, provided all four cortices have bridged.

Fig. 3

Radiographs of (left) a young man with a history of clubfoot and a 3 cm left tibial discrepancy (second left) obtained after lengthening by 3 cm. The external fixation spans the ankle to prevent equinus, and the distal tibial fibular syndesmosis is transfixed with a bone screw. The nail rises up during lengthening, but it still has sufficient length in the distal segment for stability; (second right) showing nail is locked distally, and external fixation is removed. The distal tibial fibular screw prevents proximal migration of the distal fibula; and (right) obtained four months after nail is locked showing that complete healing has been achieved (copyright 2015, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore).

LON group

We performed 19 tibial LON procedures in 16 patients (seven male, nine female), three of whom had simultaneous bilateral tibial lengthening (Table IV). The mean follow-up time calculated from the first surgery was 23 months (nine to 52). The mean age was 27 years (15 to 62). The indications for lengthening were limb-length discrepancy in 13 patients and lengthening for stature in three patients. The aetiology of leg-length discrepancy or short stature was classified as congenital in five tibias, developmental (for example, leg-length discrepancy owing to growth arrest (post-fracture, sepsis, radiation, Blount disease, and avascular necrosis), spina bifida, Klippel-Trenaunay syndrome, and short stature (owing to achondroplasia or growth hormone deficiency)) in nine tibias, and post-traumatic (secondary to acute shortening from fractures and post-tumour resection) in five tibias. In one patient, who had both a leg-length discrepancy and a post-traumatic nonunion of the distal tibia, the LON technique was used simultaneously to lengthen and achieve healing of the nonunion site. In another patient, both tibial and femoral LON procedures were performed simultaneously.

For the patients in the LON group, the difficulty levels for each lengthening were calculated as six mild, ten moderate, and three severe. Three patients had an acute correction of a tibial deformity at the time of the osteotomy. Orthofix monolateral fixators (Orthofix, McKinney, Texas) were used in two tibias, and Ilizarov circular fixators (Smith & Nephew Orthopedics, Memphis, Tennessee) were used in the remaining 17 tibias. For those patients in whom we used the circular fixator, we included the entire foot in the frame in two, and the heel only in five patients (one who was a bilateral tibial lengthening patient). We injected the gastrocsoleus muscle with a Botulinum toxin (Allergan, Inc., Irvine, California) to prevent equinus contracture of the feet in one patient who had bilateral tibial lengthenings.

Ace nails (Ace Medical Company, Los Angeles, California) were used in ten cases, and Russell-Taylor Delta tibial nails (Smith & Nephew Orthopedics, Memphis, Tennessee) were used in seven cases. In the two remaining cases, an AO nail (Synthes, Paoli, Pennsylvania) and a Gross-Kempf nail (Howmedica, Rutherford, New Jersey) were already in place from previous surgeries and were therefore used for lengthening. Except for one case, all nails were inserted and locked proximally, and at the time of fixator removal, the nails were locked distally. In the one case, the nail was inserted retrograde from the heel to obtain an ankle fusion and was later locked proximally.

There were six additional surgeries at the time of frame application in the LON group: three tarsal tunnel decompressions, two Achilles tendon lengthenings, and one flexor digitorum longus tendon lengthening.

The tibial osteotomy was achieved with a percutaneous technique by using a Gigli saw in 12 cases, a modified percutaneous multiple drill hole technique in four cases, and the classical Ilizarov corticotomy with an osteotome in three cases. The tibial osteotomy level was at the metaphyseal-diaphyseal junction in two tibias, purely diaphyseal in 13 tibias, and metaphyseal in three tibias. In one tibia, no osteotomy was performed as the lengthening was achieved through a gradual distraction of a nonunion site that was percutaneously drilled.

In total, 12 patients were asked to donate blood before surgery, considering the potential blood loss caused by reaming the intramedullary canal of the tibia. None of the patients in the matched case group were asked to pre-deposit autologous blood.

Ilizarov group

The Ilizarov tibial lengthening matched case group consisted of 17 patients (11 male, six female) who had a total of 19 tibial lengthenings using only circular external fixation. All patients were followed prospectively for a minimum of two years. The mean age of the patients in this group was 27 years (13 to 54). The indications for lengthening were leg-length discrepancy in 15 patients, and lengthening for stature in two patients (who underwent simultaneous bilateral tibial lengthening). The aetiology was classified as post-traumatic in nine cases, congenital in one case, and developmental in nine cases. In one patient who had both a leg-length discrepancy and a post-traumatic nonunion of the distal tibia, the Ilizarov technique was used to simultaneously lengthen the tibia through a proximal tibial osteotomy and achieve healing of the nonunion site. One patient had a simultaneous lengthening of the tibia and femur. In six patients, we performed a double-level osteotomy to obtain a bifocal lengthening. The tibial osteotomy was achieved by using a Gigli saw in four cases and a classical Ilizarov corticotomy with an osteotome in the remaining 15 cases. The osteotomy level was diaphyseal in two cases, metaphyseal in 14 cases, and metaphyseal-diaphyseal in three cases. In ten patients, we included the entire foot in the frame. The pre-operative levels of difficulty were calculated as six mild, ten moderate, and three severe.

Outcomes

All the patients in both groups, including the two distal tibial nonunions, achieved a complete consolidation of the new bone. The mean lengthening was 5.2 cm (2.0 to 10.2) in the LON group and 4.9 cm (1.3 cm to 12.5 cm) in the matched case group. The mean external fixation time in the LON group was 2.6 months (1.4 to 3.8) and 7.6 months (four to 18) for patients in the matched case group. The difference in external fixation times was significant (p = 0.004). In two LON patients, the external fixator was not removed immediately at the end of the distraction phase in order to provide additional temporary support for a long distraction gap. The mean external fixation index was 0.7 months per cm (0.5 to 1.1) for the LON group and 2.3 months per cm (1.1 to 8.1) in the matched case group. The difference in the external fixation index between the two groups was significant (p = 0.009). The mean radiographic consolidation time, determined in 15 LON cases, was 6.6 months (four to ten). Four cases did not have a sufficient number of radiographs to determine the radiographic consolidation time. The matched case group had a mean radiographic consolidation time of 7.6 months (4 to 18). The difference in the radiographic consolidation time between the two groups was not significant (p = 0.7). The radiographic consolidation index was 1.4 months per cm (0.7 to 3.4) in the LON group and 2.3 months per cm (1.1 to 8.1) for the matched case group. This difference in the radiographic consolidation index was not significant (p = 0.15).

There were no evident differences in the mechanical axis displacement owing to the lengthening with circular fixation. The monolateral fixator tended to push the lengthened tibia into slight valgus, which resolved after locking the nail and removing the fixator. The mean cost for patients in the LON group was $30 802 ($25 946 to $42 202) while the mean cost for patients in the matched case group was $20 480 ($15 500 to $27 875). This cost difference was significant with p < 0.0001. Mean operative time was four hours (three to seven) for the LON group and 4.6 hours (2.7 to 6.0) for the matched case group. The difference between the two groups with respect to operative time was not significant (p = 0.63). The mean blood loss for the LON group was 280 ml (100 to 600) and 100 ml (30 to 200) for the matched case group. The difference in blood loss was significant (p = 0.004). Four LON patients received an autologous blood transfusion post-operatively, whereas none of the patients in the matched case group needed this additional intervention. The rate of additional unplanned surgeries for the LON group was 31%, while that for the matched case group was 42%. This was not significant (p = 0.58).

Functional outcomes

Full weight-bearing for patients in both groups was permitted after a mean of 4.8 months (2.6 to 6.8). All patients in both groups regained their pre-operative knee and ankle ROM. The mean total arc of movement for the ankle pre-operatively in the LON patients was 49° while post-operatively it was 54° (p = 0.33). For the matched case patients, the mean pre-operative ankle total arc of movement was 49°, while post-operatively it was 50° (p = 0.85).

In the LON group, the tibial lengthening outcome score was excellent in 17 cases and good in two cases (Table IV). In the matched case group, the outcome score was excellent in 14 cases and good in five cases.

Seven cases in the matched case group had improvements in gait after treatment - four cases improved from a slight limp to no limp and three cases improved from a moderate limp to a slight limp. Two cases had no limp before treatment and had a slight limp after treatment. Five cases had no change in gait after treatment with the Ilizarov method - one case had a slight limp that remained after treatment and four cases had no limp.

Gait improved in 12 cases that had LON treatment: four cases improved from a slight limp to no limp, seven cases improved from a moderate limp to a slight limp, and one case improved from a moderate limp to no limp. Seven cases had no change in gait before and after LON treatment - two cases had a slight limp and five cases had no limp.

In three LON patients, we corrected axial deviations that developed during the lengthening by using external hinges placed on the circular frame. Seven patients in the matched case group developed axial deviation during lengthening.