INDICATIONS AND PREOPERATIVE PLANNING
Tibial lengthening with an intramedullary (IM) nail is indicated for skeletally mature patients with limb length discrepancy below the knee who have an open IM canal that is large enough diameter to fit the IM nail. Angular deformity, where the apex of the deformity is located in the zone from the proximal meta-diaphyseal tibia to the mid diaphysis, and rotational deformity can be corrected acutely using this approach. The osteotomy is usually performed 7 to 15 cm from the proximal joint line site (Fig. 1). The nail length is chosen using the shortest nail length analysis aimed to maintain 5 cm of the thick part of nail in the distal segment at the end of distraction (reviewed in chapter one). The entry point of the nail is at the anterior proximal corner of the tibia in the sagittal plane. In the coronal plane, if there is no deformity, the entry is at the proximal end of the anatomic axis line of the tibia. If there is angular deformity, then preoperative anatomic and mechanical axis planning helps to determine the optimal entry point and direction of the nail in the proximal segment as well as the blocking screw(s) location (Fig. 2).
The width of the IM canal is often greater than the diameter of the nail, and the nail will not automatically correct the angular deformity. Furthermore, there are typical deformities that ensue during a tibial lengthening-valgus and apex anterior. Blocking screws can be used to assist with acute deformity correction and prevention of lengthening induced deformities. The blocking screw is typically placed adjacent to the osteotomy site in the concavity of the deformity that is to be prevented or corrected (Fig. 3). In the absence of deformity, the blockings screws are inserted after nail insertion if the width of the IM canal is greater than the nail at the osteotomy site. If there is angular deformity present, blocking screws and a fixator assisted nailing technique are used.
The patient is positioned supine on a radiolucent table with the image intensifier on the opposite side of the surgical extremity. A 2 cm incision is made just lateral to the anterior crest of the tibia at the planned osteotomy location. The periosteum is elevated and multiple drill holes are made with a sharp drill bit (I prefer 4.8 mm) in a multiplanar transverse fashion. There are 2 versions of this technique depending in the clinical circumstance: (1) If there is no deformity or if there is only torsional deformity; (2) If there is angular deformity in the coronal and/or sagittal planes.
If acute correction is planned, prophylactic fasciotomy of the anterior and lateral compartments is performed. The knee is then flexed over a triangle, and a 2.4 mm Steinman pin is placed into the IM canal through the anterior proximal corner of the tibia. A 3 cm incision is made over the pin and the patella tendon is longitudinally split. Alternatively, a suprapatellar tendon approach may be used. A 12 mm cannulated acorn reamer is used to open the canal. In the absence of angular deformity, the guidewire is inserted and sequential reaming is done without use of a tourniquet. Flexible reamers are used to ream the IM canal about 2 mm larger than the diameter of the nail. The IM reamings egress through the drill (vent) holes. Steinmann pins or temporary external fixation pins are placed in the proximal and distal bone segments away from the nail tract to mark rotation (Fig. 4). If there is rotational deformity, the pins are placed with the desired axial plane angular divergence. The osteotomy is completed with an osteotome and then the internal lengthening nail (ILN) is passed across the osteotomy site. The fibula may be left intact at this point to provide leg stability if there is no angular deformity or if there is only torsional deformity that needs to be corrected. Proximal interlocking screws (usually 2) are inserted via the jig and then the jig is removed. Now with the knee in extension, the fibula osteotomy is performed through a lateral approach using the plane between the lateral and posterior compartments. A multiple drill-hole transverse osteotomy technique is used. A 1.8 mm wire is used to the drill holes into the fibula and the osteotomy is completed with an osteotome. Rotation of the bone around the nail confirms a complete osteotomy. Torsional deformity may be corrected at this time as needed. Distal interlocking screws (usually 2) are inserted using a freehand technique. Anterior to posterior blocking screw(s) is/are inserted lateral to the nail if at the osteotomy site there is space between the ILN and the lateral cortex (Fig. 5A). This is to prevent unwanted valgus during lengthening. Medial to lateral blocking screw(s) is/are inserted posterior to the nail if at the osteotomy site, there is space between the ILN and the posterior cortex (Fig. 5B). This is to prevent unwanted flexion during lengthening.
If there is preoperative angular deformity present, the technique is different and utilizes fixator assisted nailing and blocking screw insertion before the osteotomy. The 2 pin external fixator is placed so the pins are outside of the tract of the IM nail. Each pin is placed in the respective segment orthogonal to the axis of that segment. The proximal pin is inserted from the medial side and is posterior to where the nail will be and the distal pin is inserted from the medial side distal to where the nail will be (Fig. 3). This stabilizes the tibia in the corrected position after the osteotomy during the IM canal reaming (Fig. 6). The pins also mark the rotational alignment of each segment so that rotational deformity can be prevented or corrected as needed. In this situation, fibula osteotomy and tibial osteotomy are done and the temporary external fixator is used to hold the tibia in the corrected position before reaming. Furthermore, the entry point and the blocking screws guide the reamer in the desired direction to enable optimal deformity correction (Fig. 7).
Stabilization of the fibula to the tibia is essential during tibial lengthening. The proximal and distal tibia-fibula relationships are stabilized before lengthening of the tibia. This ensures that the fibula osteotomy will separate and lengthen along with the tibial osteotomy (Fig. 7F). Although cannulated wire technique may be used, solid 4.5 mm are needed. Smaller or cannulated screws are likely to break. Omission of this step would result in proximal migration of the distal fibula and distal migration of the proximal fibula despite a fibula osteotomy. Complications of deformity and contracture of the ankle and knee would ensue if this step were omitted.
If there is bone loss at the ankle and distal tibia, then a bifocal approach may be used. The ankle is reconstructed and the length can be restored at a proximal tibial lengthening site (Fig. 8).
Soft-tissue procedures may be needed. Acute correction of tibial deformity carries a risk of compartment syndrome and nerve injury. Adjuvant procedures of prophylactic fasciotomy and peroneal nerve decompression may be appropriate. Gastrocsoleus recession may be needed to prevent or treat equinus contracture during tibial lengthening of over 4 cm (Tables 1, 2).
TABLE 1 -
Tips for Success
|During tibial lengthening, valgus and flexion deformities are prone to occur. Blocking screws lateral and posterior to the nail at the osteotomy site can be used to prevent unwanted deformity
|If there is preoperative angular deformity present, the technique utilizes fixator assisted nailing and blocking screw insertion before the osteotomy. The 2 pin external fixator is placed so the pins are outside of the tract of the IM nail
|Entry point, trajectory of nail in proximal segment, and location of blocking screws controls the deformity correction
|Fibula length stabilization screws should be solid 4-5 mm screws and should be inserted in an oblique direction to enhance the resistance for fibula migration
|Multiple drill-hole osteotomy technique is a low energy osteotomy that minimizes thermal necrosis. Multiple drill holes are made in a transverse fashion at the osteotomy level with a new sharp 4.8 mm drill. Then complete the transverse osteotomy with a sharp osteotome
|In the absence of angular deformity, the fibula may be left intact for leg stability until after passage of the IM nail across the tibial osteotomy
IM indicates intramedullary.
TABLE 2 -
|Fibula length stabilization screws are needed to ensure that the fibula separates along with the tibia. Omission of this step would lead to proximal migration of the distal fibula and distal migration of the proximal fibula resulting in ankle and knee deformity and contracture
|The most important physiotherapy stretching exercise is ankle dorsiflexion with the knee in extension to stretch the gastrocsoleus complex to prevent equinus contracture
|With acute correction of deformity, perform fasciotomy to prevent compartment syndrome
|With acute correction of large valgus deformity, consider peroneal nerve decompression to prevent stretch injury of nerve
|Consider gastrocsoleus recession for lengthening of >4 cm to prevent equinus contracture
|Distraction should be slower in the tibia than in the femur. In most adults, distract 0.2 mm, 3-4 times/d. In teenagers, distract 0.2 mm, 4-5 times/d
Patients are hospitalized for 2 nights after surgery. Intravenous antibiotics are administered before surgery and for 24 hours after surgery. Prophylaxis for deep venous thrombosis is administered for 2 to 4 weeks depending on the activity level of the patient.
Distraction usually begins on postoperative day 7 at a rate of 0.2 mm 4 times per day. In the case of acute deformity correction, the latency phase may be increased and the distraction rate may be slowed. Knee range of motion is started immediately with a continuous passive motion machine in the recovery room. Partial weight-bearing ambulation based on the diameter of the implanted rod is begun on postoperative day 1. Radiographs are obtained every 2 to 3 weeks and the distraction rate is adjusted accordingly. In most cases, 0.2 mm 3 to 4 times per day works well in the tibia. The most important physiotherapy stretching exercises are knee extension, knee flexion, and ankle dorsiflexion with the knee in extension to stretch the gastrocsoleus complex. Full weight-bearing is allowed when there is bridging bone at 2 to 3 cortices of the regenerate (Tables 1, 2).
1. Fragomen AT, Rozbruch SR. Lengthening and deformity correction about the knee using a magnetic internal lengthening nail
. SICOT J. 2017;3:25.
2. Kocaoglu M, Eralp L, Bilen FE, et al. Fixator-assisted acute femoral deformity correction and consecutive lengthening over an intramedullary nail. J Bone Joint Surg Am. 2009;9:152–159.
3. Krettek C, Miclau T, Schandelmaier P, et al. The mechanical effect of blocking screws (“Poller screws”) in stabilizing tibia fractures with short proximal or distal fragments after insertion of small diameter intramedullary nails. J Orthop Trauma. 1999;13:550–553.
4. Muthusamy S, Rozbruch SR, Fragomen AT. The use of blocking screws with internal lengthening nail
and reverse rule of thumb for blocking screws in limb lengthening and deformity correction surgery. Strategies Trauma Limb Reconstr. 2016;11:199–205.
5. Nogueira MP, Paley D, Bhave A, et al. Nerve lesions associated with limb lengthening. J Bone Joint Surg Am. 2003;85-A:1502–1510.
6. Paley D, Herzenberg JE, Bor N. Fixator-assisted nailing of femoral and tibial deformities. Tech Orthop. 1997;12:260–275.
7. Paley D. PRECICE intramedullary limb lengthening system. Expert Rev Med Devices. 2015;12:231–249.
8. Rozbruch SR, Birch JG, Dahl MT, et al. Motorized intramedullary nail for treatment of limb length discrepancy and deformity. J Am Acad Orthop Surg. 2014;22:403–409.
9. Rozbruch SRRozbruch SR, Hamdy RC. Case 2: Tibia lengthening with precice internal lengthening nail
. Limb Lengthening and Reconstruction Surgery Case Atlas Adult Deformity-Tumor-Upper Extremity. Cham, Switzerland: Springer International Publishing; 2015:13–18.
10. Rozbruch SR. Adult posttraumatic reconstruction using a magnetic internal lengthening nail
. J Orthop Trauma. 2017;31(suppl 2):S14–S19.
11. Rozbruch SR, Zonshayn S, Muthusamy S, et al. What risk factors predict usage of gastrocsoleus recession during tibial lengthening
? Clin Orthop Relat Res. 2014;472:3842–3851.
12. Rozbruch SR, Fragomen AT. Tibial/Femoral Osteotomy in Andrew Green, MD, and Roman Hayda, MD: Orthopaedic Postoperative Rehabilitation, American Academy of Orthopaedic Surgeons; 2017.