Abstract
Background: This study was performed to determine the safety and effectiveness of lengthening of the tibia, in patients who have a limb-length discrepancy or a short stature, with use of distraction osteogenesis, a technique based on the principle of distracting the callus that is formed after a subperiosteal osteotomy of the proximal portion of the diaphysis of a long bone.Methods: A total of 230 tibial lengthening procedures were done in 150 patients. Seventy procedures were performed because of a limb-length discrepancy, which was secondary to trauma (thirty limbs), congenital fibular hemimelia (twenty-six), poliomyelitis (ten), or infection (four). The remaining 160 procedures were performed because of a short stature, which was secondary to achondroplasia (fifty-eight limbs), Turner syndrome (thirty-four), an idiopathic etiology (twenty-two), hypochondroplasia (twenty), achondroplasia (ten), Ellis-van Creveld syndrome (six), rickets (four), or adrenogenital syndrome, Laron syndrome, or pseudoachondroplasia (two limbs each). The age of the patients at the time of the operation was 18.4 ± 6.2 years (average and standard deviation), with a range of six to forty-one years.The procedures were performed according to one of three protocols. In Group A (ninety procedures), an Orthofix telescopic fixator and a variable number of screws were used and the tibiofibular syndesmosis was not stabilized; in Group B (ninety-six procedures), an Orthofix reconstruction system was used, the syndesmosis was stabilized, and a tenotomy of the Achilles tendon was performed; and in Group C (forty-four procedures), an Orthofix Garches lengthening device was used, the syndesmosis was stabilized, and a tenotomy of the Achilles tendon was performed.Results: At the time of the latest follow-up (average, five years; range, two to seven years), the average gain in length after the seventy procedures performed because of a limb-length discrepancy was 4.0 ± 1.98 centimeters (range, 2.5 to 9.5 centimeters), or 14 percent (range, 7 to 45 percent). The average gain in length after the 160 procedures that were performed because of a short stature was 7.8 ± 2.28 centimeters (range, 2.5 to fifteen centimeters), or 33 percent (range, 10 to 78 percent). Ten (14 percent) of the seventy procedures performed because of a limb-length discrepancy and forty-six (29 percent) of the 160 performed because of a short stature were associated with a complication. There was only one permanent sequela in the entire series.Conclusions: Although the three operative protocols resulted in similar healing indices, the rates of complications differed significantly among the groups (p < 0.0001). Group C (the Garches device) had the lowest rate of complications (7 percent). It is important to be aware of potential complications as well as the need for additional procedures in order to avoid predictable problems. These procedures include percutaneous tenotomy of the Achilles tendon and fixation of the distal segment of the fibula to the tibia to maintain the integrity of the tibiotalar articulation and the alignment of the foot.
The distraction osteogenesis technique, developed by De Bastiani, myself, Renzi-Brivio, and Trivella at the Department of Orthopaedics at the University of Verona9, has been our procedure of choice for lengthening of the long bones1. This technique consists of distracting the callus that is formed after a subperiosteal osteotomy of the proximal portion of the diaphysis of a long bone. The results of two series of tibial lengthening procedures (consisting of forty-one9 and 124 procedures3) that were performed with use of this method were reported previously. Retrospective analysis of these two series confirmed the usefulness and effectiveness of the technique and identified methods of avoiding some of the expected problems1,9,16.
In the current study, the results of tibial lengthening, performed with modifications of the original distraction-osteogenesis protocol, were reviewed to determine whether the type of fixator or the simultaneous performance of additional procedures affected the outcome.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
†Department of Orthopaedics, Policlinico Borgo Roma, 37134 Verona, Italy.
Between January 1990 and December 1995, 230 tibiae in 150 patients (eighty-eight male patients and sixty-two female patients) were lengthened (Table I). The age of the patients at the time of the operation was an average (and standard deviation) of 18.4 ± 6.2 years (range, six to forty-one years). Patients who had osteogenesis imperfecta, congenital pseudarthrosis of the tibia, partial or total agenesis of the tibia, or a traumatic injury with extensive crushing of soft tissues and disruption of neurovascular structures resulting in a severe, complex deformity of the leg were excluded from the study as they often needed more definitive treatment, such as an amputation or a disarticulation at the knee or ankle and use of an orthotic device or prosthesis.
The average duration of follow-up was five years (range, two to seven years). Seventy patients (seventy tibiae) had a limb-length discrepancy. Their average age was twenty years (range, six to forty-one years) at the time of the operation. The etiology of the limb-length discrepancy was trauma in thirty patients (fifteen had a growth-plate injury), congenital fibular hemimelia in twenty-six, poliomyelitis in ten, and infection in four. On the basis of the classification of fibular hemimelia proposed by Dal Monte et al.8, twenty-two patients had type I (a small fibula, valgus deviation and pronation of the foot, and less than 15 percent shortening), three had type II (a hypoplastic fibula, deformity of the tibiotalar joint and foot, and less than 35 percent shortening), and one had type III (aplasia of the fibula, a very severe tibiotarsal deformity, and at least 40 percent shortening). Several patients who had a short tibia secondary to trauma or a congenital anomaly had associated angular (varus or valgus) and rotational deformities, congenital or secondary instability of the knee and the tibiotalar joint, or a congenital deformity of the foot.
Eighty patients who had a short stature secondary to various etiologies had bilateral lengthening of the tibia (160 procedures). The average age of the patients at the time of the first operation was eighteen years (range, eleven to thirty-one years). Twenty-nine patients (fifty-eight tibiae) had achondroplasia; seventeen (thirty-four tibiae), Turner syndrome; eleven (twenty-two tibiae), no specific etiology; ten (twenty tibiae), hypochondroplasia; five (ten tibiae), chondrodysplasia; three (six tibiae), Ellis-van Creveld syndrome; two (four tibiae), rickets; and three each (six tibiae), adrenogenital syndrome, Laron syndrome, or pseudoachondroplasia.
An anthropometric chart6 was used to calculate percentage ratios between standing height, sitting height, and the length of the long bones of the upper and lower extremities as measured on radiographs of normal individuals who were matched for the age and gender of the patient. The chart is based on the average values for all races, and I believe that these values are universally valid. There was a disproportion between the length of the trunk and that of the lower extremities in all patients who had a short stature.
During the six-year period of the study, lengthening was attained with use of three types of Orthofix external fixators: the telescopic device, the reconstruction system, and the Garches device (Orthofix S.R.L.; Bussolengo, Verona, Italy) (Figs. 1, 2, and 3). The choice of device was not based on any specific characteristics of the patient or on the etiology of the shortening but, rather, on the availability of the device.
In Group A, which comprised ninety tibiae (sixteen in patients who had a limb-length discrepancy and seventy-four in patients who had a short stature), the osteotomy was performed through an anteromedial incision and the site was stabilized with the telescopic fixator, cortical-bone screws were inserted parallel to the posterior surface of the tibia, and one centimeter of the distal third of the fibula was excised. The tibiae in this group were further classified on the basis of the number of screws that were used. In Subgroup A1, two screws were inserted in each segment; in Subgroup A2, three screws were inserted in the proximal segment and two, in the distal segment; and in Subgroup A3, three screws were inserted in each segment. (More screws are currently used as this appears to decrease the risk of osteolysis.) Subgroup A1 comprised fourteen tibiae (four in patients who had a limb-length discrepancy and ten in those who had a short stature); Subgroup A2, fifty-six tibiae (seven in patients who had a limb-length discrepancy and forty-nine in those who had a short stature); and Subgroup A3, twenty tibiae (five in patients who had a limb-length discrepancy and fifteen in those who had a short stature).
In Group B, which included ninety-six tibiae (thirty in patients who had a limb-length discrepancy and sixty-six in patients who had a short stature), the osteotomy was performed through an anterolateral incision with transection of the outer half of the muscle fascia, the fibula was fixed to the tibia with an AO internal fixation screw placed obliquely through the tibiofibular syndesmosis in a proximal and posterior direction, one-half centimeter of the distal third of the fibula was excised, a percutaneous tenotomy of the Achilles tendon was performed at three levels, and a cast-boot was applied with the tibiotalar joint in a neutral position. The osteotomy site was stabilized with the reconstruction device, and three cortical-bone screws were inserted in each segment, from the anterior surface. Postoperatively, a suction drain was used for twenty-four hours. The cast was replaced on the second postoperative day and every thirty days thereafter throughout the period of distraction. The syndesmosis screw was removed six months after removal of the fixator, with the patient under local anesthesia.
In Group C, which comprised forty-four tibiae (twenty-four in patients who had a limb-length discrepancy and twenty in patients who had a short stature), the osteotomy was performed through an anterolateral incision after the insertion of the patellar ligament had been exposed and the outer half of the muscle fascia had been transected. The osteotomy site was stabilized with the Garches device14. Three cortical-bone screws were placed in each segment except when the growth plate was open, in which case only two screws were inserted, in the proximal metaphysis of the tibia. The distal part of the fibula was transfixed to the tibia with insertion of an AO screw through the tibiofibular syndesmosis, a segment of the fibula was excised, and a tenotomy of the Achilles tendon was performed. Postoperatively, the ankle was immobilized in a plaster cast-boot, and a suction drain was used for twenty-four hours.
Major associated rotational and angular deformities usually were corrected at least one year before the lengthening procedure. Slight varus and rotational deformities usually were corrected at the time of the index procedure; however, valgus deformities were corrected only at the end of the period of distraction. Laxity of the ligaments and deformities of the foot were corrected after osseous consolidation of the lengthened segment.
Distraction was started on the tenth postoperative day at a rate of one millimeter per day for the first centimeter of lengthening; this rate was subsequently adjusted commensurate with the degree of ossification seen on the radiographs. The radiographic appearance of a layer of cortical bone in the lengthened segment signaled the need for compression of the segment. This was achieved either by releasing the clamps, which allowed the two ends of the fixator to slide, or by removing one screw from each segment to decrease the rigidity of the device.
The patients were allowed to walk with crutches as early as the first postoperative day, and weight-bearing was increased gradually16. The patients in Groups B and C followed an independent home-exercise program. During the period of distraction, the patients were allowed to bear weight while wearing the plaster cast. After removal of the cast, the patients were able to regain motion of the ankle joint without formal physical therapy; however, supervised physical therapy was provided if there was any evidence of muscle imbalance.
The parameters that were assessed to determine the outcome included the increase in length, the time to consolidation, the delay in consolidation, complications, and long-term sequelae. The increase in length was measured on radiographs of both lower extremities, made with a tube-to-film distance of two meters with the patient in the supine position. The increase in length was expressed in centimeters and as a percentage of the preoperative length of the tibia. The time to consolidation was calculated as the number of days required for complete healing of one centimeter of lengthened bone and was expressed as the healing index1. A delay in consolidation was recorded when healing was prolonged but occurred without the need for additional procedures. A healing index of more than fifty days per centimeter implied a delay in consolidation. Complications included problems that resolved with and without additional operations and did not affect the outcome. Problems related to the fixator were not considered to be complications as they were expected and were easily resolved. Sequelae were irreversible complications that caused permanent functional disability.
The length of the 230 tibiae increased an average (and standard deviation) of 6.6 ± 0.2 centimeters (range, 2.5 to fifteen centimeters), or 27 percent (range, 7 to 78 percent). The seventy tibiae in the patients who had a limb-length discrepancy were lengthened by an average of 4.0 ± 1.98 centimeters (range, 2.5 to 9.5 centimeters), or 14 percent (range, 7 to 45 percent), and the 160 tibiae in the patients who had a short stature were lengthened by an average of 7.8 ± 2.28 centimeters (range, 2.5 to fifteen centimeters), or 33 percent (range, 10 to 78 percent).
The average time until osseous consolidation (the healing index), estimated for 174 tibiae, was 44.6 ± 1.53 days per centimeter (range, eighteen to 110 days per centimeter). (The remaining fifty-six tibiae were excluded from this calculation because complications necessitated additional operations.) Fifty-two tibiae were considered to have had delayed consolidation although the bone healed spontaneously; the average healing index for these tibiae was seventy-two days per centimeter (range, fifty-one to 110 days per centimeter). The remaining 122 tibiae had an average healing index of 39.1 ± 1.69 days per centimeter (range, eighteen to fifty days per centimeter).
A total of fifty-six complications (24 percent) occurred in the entire series (Table II). Ten (14 percent) of the seventy procedures that were performed because of a limb-length discrepancy were associated with a complication. Seven of these complications were related to problems with the osteogenesis: valgus deviation developed in three legs because of a deformity of the lengthened segment after removal of the external fixator, the osteogenesis was insufficient in two, and the bone failed to consolidate in two. The other three complications were related to osteolysis around the proximal screws, which led to loosening of the fixator. Forty-six (29 percent) of the 160 procedures that were performed because of a short stature were associated with a complication. Thirty-one of these complications were related to osteogenesis: valgus deviation developed in eighteen legs, there was premature fusion of the fibular osteotomy site during distraction in seven, the osteogenesis was insufficient in three, fracture occurred in two, and the bone failed to consolidate in one. Thirteen complications were related to the external fixator: instability due to osteolysis developed in twelve legs, and infection developed with formation of an abscess in one. The remaining two complications were related to the position of the patella, with one high-riding patella and one low-riding patella. There was one permanent sequela, consisting of stiffness of the ankle joint secondary to an unrecognized subluxation, in a twenty-two-year-old woman with a short stature who had Turner syndrome.
Talipes equinus was not considered a complication because this deformity is to be expected in any patient who has a major lengthening procedure and it can be avoided by lengthening the Achilles tendon at the time of the osteotomy. Of the ninety limbs in Group A, twenty-nine (six in patients who had a limb-length discrepancy and twenty-three in those who had a short stature) had lengthening of the Achilles tendon at a later date. The protocol for Group A did not include a percutaneous tenotomy of the Achilles tendon or use of a cast-boot, whereas the protocol for Groups B and C included both of these measures.
The ninety tibiae in Group A (the telescopic fixator) had an average increase in length of 6.8 centimeters (range, 3.5 to 11.5 centimeters), or 26 percent (range, 14 to 63 percent). The average healing index was forty-four days per centimeter (range, thirty to 110 days per centimeter), and consolidation was delayed in twenty-five tibiae (28 percent). Of the ninety procedures, thirty-five (39 percent)—five of the sixteen performed because of a limb-length discrepancy and thirty (41 percent) of the seventy-four performed because of a short stature—were associated with a complication (Table III). Valgus deviation and loosening of the fixator due to osteolysis were seen in five of the fourteen tibiae in Subgroup A1, in seventeen of the fifty-six in Subgroup A2, and in two of the twenty in Subgroup A3. The remaining eleven complications had no particular pattern of distribution among the three subgroups.
A typical sequence of events after the index procedure in Group A (the telescopic fixator) is seen on the radiographs (Figs. 4-A, 4-B, 4-C and 4-D) of an eleven-year-old boy who had a congenital limb-length discrepancy, with the right extremity 15 percent shorter than the left. The tibia was lengthened five centimeters. The osteotomy site was stabilized with the fixator, and two screws were inserted in each segment (Subgroup A1) (Fig. 4-A). Signs of consolidation in the lengthened segment were seen during the period after removal of the fixator to allow compression of the fragments (Fig. 4-B). One year after consolidation, there had been complete remodeling of the tibia (Figs. 4-C and 4-D).
The average increase in the length of the ninety-six tibiae in Group B (the reconstruction device) was 6.7 centimeters (range, three to fifteen centimeters), or 28 percent (range, 11 to 78 percent). The average healing index was thirty-seven days per centimeter (range, twenty-four to eighty-seven days per centimeter). Twenty tibiae (21 percent) had delayed consolidation. Eighteen procedures (19 percent)—four (13 percent) of the thirty performed because of a limb-length discrepancy and fourteen (21 percent) of the sixty-six performed because of a short stature—were associated with a complication (Table III). Twelve complications were related to osteogenesis and five, to the external fixator.
A typical sequence of events after the index procedure in Group B (the reconstruction device) is seen on the radiographs (Figs. 5-A, 5-B, 5-C and 5-D) of a fourteen-year-old boy who had a short stature secondary to achondroplasia. The fixator was placed with three screws in each segment (Fig. 5-A). At the end of the period of distraction, after the tibia had been lengthened thirteen centimeters (an increase of 60 percent), there were signs of consolidation (Fig. 5-B). Six months after removal of the fixation device, consolidation and remodeling of the lengthened segment were noted, although the entire bone appeared somewhat osteopenic (Figs. 5-C and 5-D).
The forty-four tibiae in Group C (the Garches device) had an average increase in length of 5.8 centimeters (range, 2.5 to eight centimeters), or 27 percent (range, 7 to 43 percent). The average healing index was thirty-nine days per centimeter (range, eighteen to seventy-seven days per centimeter). Seven tibiae (16 percent) had delayed consolidation. Three procedures (7 percent)—one (4 percent) of the twenty-four performed because of a limb-length discrepancy and two (10 percent) of the twenty done because of a short stature—were associated with a complication (Table III). Two of the three complications were related to osteogenesis.
A typical sequence of events after the index procedure in Group C (the Garches device) is seen on the radiographs (Figs. 6-A, 6-B, and 6-C) of a twelve-year-old girl who had a congenital limb-length discrepancy, with the right lower extremity 16 percent shorter than the left. The fixator was placed with insertion of two screws in the proximal segment and three in the distal segment (the growth plate was open) (Fig. 6-A). The lengthened segment began to consolidate after the central screw in the distal segment of the diaphysis was removed to decrease the rigidity of the fixator (Fig. 6-B). Six months after removal of the fixator, the bone had consolidated and had begun to remodel (Fig. 6-C).
Of the fifty-six complications, thirty-eight occurred during the stage of bone consolidation. In twenty-one tibiae, a valgus deviation of more than 10 degrees developed within six months after removal of the fixator. Five tibiae had insufficient osteogenesis, and three had a failure of consolidation. The fibular osteotomy site fused during the distraction period in seven legs, and two tibiae fractured after removal of the screws. A residual valgus deviation of as much as 10 degrees was considered inevitable in patients who had a congenital or neurological disorder and in those with a short stature who had a very high percentage increase in length. I believe that the desire and the indication for a corrective osteotomy in patients who have a valgus deformity of 10 degrees or less are based on aesthetic considerations rather than on functional deficit. For these reasons, valgus deviation of 10 degrees or less was not regarded as a complication.
Sixteen complications were related to the fixator: fifteen were due to loosening of the device secondary to osteolysis around the screws of the proximal clamp, and one was due to a Staphylococcus aureus infection with formation of an abscess at the tip of the proximal screw.
The remaining two complications were related to the extensor mechanism of the knee. One patient had a high-riding patella because of inadequate release of the rectus femoris muscle, and the other had a low-riding patella because the level of the tibial osteotomy was too proximal.
Valgus deviation was treated with a corrective osteotomy at the apex of the deformity and internal fixation; insufficient osteogenesis, with the addition of autologous cancellous bone grafts; failure of the bone to consolidate, with intramedullary nailing; premature fusion of the fibula, with osteotomy; fracture, with fixation; loosening of the fixator, with reinsertion of the screws; the soft-tissue abscess, with curettage; the high-riding patella, with lengthening of the quadriceps tendon and rehabilitation; and the low-riding patella, with transposition of the tibial apophysis six months after consolidation of the lengthened segment. The angular deviations and the patellar problems were treated operatively six months after removal of the fixator and screws, whereas the other complications were treated while the fixator was still in place.
Distraction osteogenesis involves progressive diaphyseal lengthening by means of distraction of the callus that is formed at the site of a subperiosteal osteotomy. My colleagues and I developed this technique on the basis of experimental and clinical studies conducted from 1975 to 1985. The original technique included a subperiosteal osteotomy, which preserves the osteogenic potential of the periosteum; rigid external fixation with a device that permits conversion to a dynamic construct, such as the Orthofix fixator; a waiting period between the operation and the distraction of not more than fifteen days to facilitate healing of the intraoperative lesions and to allow callus formation to begin; controlled distraction commensurate with the rate of ossification; and dynamic compression to facilitate consolidation of the lengthened segment5.
The average age of the 150 patients was eighteen years (range, six to forty-one years). The average age of the ten patients who had poliomyelitis was twenty-nine years (range, thirteen to forty-one years), and that of the four who had an infection was twenty-five years (range, eighteen to thirty-nine years). The choice of the Orthofix fixator and screws with a diameter of five to six millimeters was based on the fact that our patients were not very young children. The average percentage increase in length was not very high in patients who had dysplasia or dysmorphism as they were older. In order to obtain the maximum increase in length in patients who have a short stature, the procedure should be performed during adolescence2,4,7,9.
The percentage of postoperative lengthening was similar for the various etiologies of limb-length discrepancy (average increase, 14 percent; range, 7 to 45 percent) as well as for the various etiologies of short stature (average increase, 33 percent; range, 10 to 78 percent). The only significant difference with regard to the percentage increase was between the tibiae with achondroplasia and those with other etiologies (average increase, 53 percent compared with 23 percent; p < 0.0001). The percentage increase in length was 14 to 22 percent in 172 (75 percent) of the 230 tibiae.
The average healing index was 37 ± 2.77 days per centimeter (range, eighteen to ninety-three days per centimeter) for the tibiae of patients who had a traumatic or congenital limb-length discrepancy and for those of patients who had a short stature secondary to achondroplasia, hypochondroplasia, chondrodysplasia, Ellis-van Creveld syndrome, or idiopathic causes; these tibiae constituted 75 percent of the entire series. Poliomyelitis, pseudoachondroplasia, Turner syndrome, adrenogenital syndrome, infection, rickets, and Laron syndrome accounted for the etiology in 25 percent of the tibiae and were associated with an average healing index of 45 ± 2.44 days per centimeter (range, thirty-nine to 110 days per centimeter). When the healing indices for the various etiologies were compared with use of analysis of variance Kruskal-Wallis test on ranks, the difference was found to be significant (p = 0.0017). This suggests that the etiology of the shortening has an effect on the time to consolidation12. I did not find any relationship between a high healing index and the percentage increase in length when there was no underlying bone disease. In contrast, there was a delay in consolidation in patients who had poliomyelitis13,14, infection, Turner syndrome13, adrenogenital syndrome, or pseudoachondroplasia, particularly in Groups A and B.
There were many instances of delayed consolidation despite the use of external fixation. These delays were probably related to osteogenesis and could not be predicted with the methods used in the present study. The reasons for delays could include the etiology of the shortening, the age of the patient, the operative technique, or the type of fixator. Critical study of patients with delayed consolidation as a separate group may suggest the need for alternative procedures such as use of a different type of fixator, intramedullary nailing11, or bone-grafting. A long interval before ossification is unsatisfactory for both the patient and the surgeon. Extended use of the external fixator increases the risk of osteolysis, instability, infection, and insufficient osteogenesis7. In the near future, it may be possible to use chemical substances and autologous tissues to enhance bone formation and consolidation10.
Group A had the highest healing index (average, forty-four days per centimeter; range, thirty to 110 days per centimeter). When the limbs that had a complication were excluded, the percentage of tibiae with a healing index of less than fifty days per centimeter was 33 percent in Group A, 60 percent in Group B, and 77 percent in Group C. The high average healing index and the low percentage of tibiae with a healing index of less than fifty days per centimeter in Group A appear to be related to the relatively poor mechanical stability of the Orthofix telescopic lengthening device used with four or five screws (Subgroups A1 and A2). The average healing index for the tibiae that did not have delayed consolidation (thirty-nine days per centimeter) is almost identical to those reported previously after the same method of limb-lengthening (forty-one days per centimeter for forty-one tibiae9 and for 124 tibiae3). Retrospective analysis of the previously published data3,9 and the data in the present study suggests that the average healing index for the described method of tibial limb-lengthening is forty days per centimeter.
The rate of complications was 14 percent after the seventy procedures performed because of a limb-length discrepancy and 29 percent (higher, as expected) after the 160 procedures performed because of a short stature2-4,10. Thirty-eight of the fifty-six complications were related to ossification (Tables II and III). Thirteen of the twenty-one valgus deviations were in Group A, and only two were in Group C. The Garches device (Group C) provides easy axial alignment and allows a more proximal osteotomy, which facilitates osteogenesis. Early fusion of the fibula occurred in Group A, whereas fixation of the fibula to the tibia in the other two groups prevented malalignment of the ankle joint. The sixteen complications associated with the fixator screws (fifteen instances of instability and one soft-tissue abscess) all occurred when the telescopic fixator and the reconstruction system were used. In contrast, there were no instances of osteolysis with use of the Garches device.
Of the fifty-six complications, thirty-five (63 percent) were in Group A, eighteen (32 percent) were in Group B, and three (5 percent) were in Group C. The difference among the three groups was significant (p < 0.0001), according to an independent test on ranks (Wilcoxon test).
Lengthening of the Achilles tendon during or at the end of distraction was necessary in twenty-nine legs, all in Group A, in which the protocol did not include this procedure. In Groups B and C, a percutaneous tenotomy was performed at the time of the osteotomy, and there were no contractures or equinus deformities. The tenotomy is an important part of the procedure as it can prevent problems related to the ankle and foot.
All patients in Groups B and C, in whom the distal aspect of the fibula was fixed to the tibia with an AO screw, had healing without elevation of the lateral malleolus or a valgus deformity of the tibiotarsal and subtalar joints. There were no complications associated with use of this screw. The screw passing through the tibiofibular syndesmosis did not stimulate ossification, and there was no instability of the fibula or limitation of dorsiflexion. Stabilization of the distal aspect of the fibula with the screw, which is removed after the fixator is removed, is another factor that decreases the rate of complications affecting the ankle and foot.
On the basis of the results in the current study and earlier experience3,9, I believe that distraction osteogenesis is a useful and effective method of lengthening. Only three of the 230 lengthening procedures did not lead to consolidation, and five were associated with insufficient osteogenesis. The lowest rates of complications were associated with the Garches device14 and the reconstruction system with insertion of three screws in each segment. Percutaneous tenotomy of the Achilles tendon and fixation of the distal aspect of the fibula to the tibia by means of an AO internal screw proved very useful in attaining stability of the tibiotalar articulation and the foot; therefore, they should be an integral part of the lengthening procedure.
NOTE: The author thanks Carlo Dall'Oca, M.D., and Silvio Galassini, M.D., Professor of Physics and Statistics at the University of Verona.
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