Reconstruction of the distal end of the tibia with an unstable ankle joint,
bone loss, and/or limb-length discrepancy is a challenging task for the
orthopaedic surgeon. Custom-made ankle replacements and other surgical
procedures combining allograft, free-tissue transfer, and ankle arthrodesis
with limb-lengthening or bone transport with use of a circular external
fixator have been utilized to treat this
condition1-16.
The use of a circular external fixator to achieve an ankle arthrodesis was
initially described to overcome the complicating problems of infection,
deformity, and/or osteoporotic
bone3. Subsequently,
the fixator has been used to achieve an ankle arthrodesis in the presence of
bone loss and a leg-length
discrepancy1,9,13-16.
Although all of these challenging problems can be addressed by the use of a
circular external fixator, this method has been associated with many
complications. Pin-site infection, refracture, nonunion, malunion, and loss of
alignment have been reported in many
series1,3,5,9,13-16.
In order to reduce these complications, we used the circular external
fixator in combination with an intramedullary nail to achieve ankle
arthrodesis, bone transport, and/or leglengthening in selected patients. This
method allows for earlier removal of the circular external fixator while the
intramedullary nail protects the regenerated bone and the ankle arthrodesis
from angulation and displacement.
The present retrospective study summarizes our experience using the
combination of a circular external fixator and an intramedullary nail for the
reconstruction of the distal end of the tibia and the ankle.
Between 2002 and 2005, six patients were managed with the combined
technique. Three of them underwent ankle arthrodesis and bone transport and
the other three underwent ankle arthrodesis and tibial lengthening with use of
a circular external fixator and an intramedullary nail. The average age of the
patients at the time of the procedure was 28.7 years (range, seventeen to
seventy years). The average size of the tibial bone defect in three patients
was 5.3 cm (2, 7, and 7 cm), and the average amount of shortening in four
patients was 5.25 cm (range, 4 to 6 cm).
Two patients (Cases 3 and 4) had a distal tibial defect following the
resection of osteomyelitis (type IVB in the Cierny-Mader classification
system)17. One of
them (Case 3) also had 6 cm of shortening. Another patient (Case 1) had a
distal tibial defect following resection of desmoid fibroma. A fourth patient
(Case 2), treated initially during childhood, had 5 cm of shortening of the
tibia with a pes calcaneovalgus deformity, following resection of the sciatic
nerve to treat fibrosarcoma. One patient (Case 5) had sequela of
poliomyelitis, and one (Case 6) had fibular hemimelia.
Demographic data were collected after reviewing the medical record and the
registry maintained in our department of the patients undergoing distraction
osteogenesis. All patients were assessed for local skin condition, shortening,
deformity, distal neurovascular status, and joint function.
The results were divided into two categories, bone results and functional
results, according to the classification system of Paley et
al.1,18
(see Appendix). The complications were evaluated according to the criteria
described by
Paley19.
Operative Technique
The operative procedure for osteomyelitis was done in two stages as
described by Kocaoglu et
al.20. During the
first stage, radical débridement with bone resection was done in the
two patients with chronic osteomyelitis. In the remaining patients, all
procedures were done during the same operation.
The procedure is performed under tourniquet control with the patient in the
supine position on a radiolucent operating table. Initially, the subtalar
joint is prepared for arthrodesis through a small incision placed over the
sinus tarsi. The foot is then positioned in correct alignment for ankle
arthrodesis. A threaded Kirschner wire is inserted through the plantar aspect
of the calcaneus, and the entry point for intramedullary nail insertion is
determined with use of an image intensifier. A cannulated drill is then
inserted over the Kirschner wire to enlarge the hole for the insertion of the
guidewire. After preparing the entry site, reaming is performed progressively
over a guidewire in 0.5mm increments.
Additional holes are predrilled in the nail (TRIGEN tibial nail; Smith and
Nephew, Memphis, Tennessee) at the planned site of locking of the segment upon
the completion of bone transport to prevent recoil of the segment. A
corticotomy is done at the appropriate level with use of a Gigli saw.
After the medullary canal has been overreamed by 2 mm, the intramedullary
nail is inserted and the distal part is locked. For bone segment transfers,
both ends are locked. For the patient with shortening, an intramedullary nail
of the eventual desired length of the tibia is inserted and left proud
proximally so that it can slide distally during treatment.
The circular external fixator construct is prepared preoperatively on the
basis of biplanar radiographs. For lengthening, two circular rings for the
proximal part of the tibia, two rings distal to the osteotomy site, and one
foot frame are assembled. The site of the ankle arthrodesis is packed with
autologous bone graft, and compression is applied with use of the ring
external fixator. The circular frames are removed after the lengthening is
completed. The locking screws are then inserted in the proximal part of the
tibia and the lengthened segment (Fig.
1).
In the case of segment transfer, three circular rings are assembled for the
proximal part of the tibia with one ring acting as a transport segment. It is
connected with the foot frame distally. Autologous bone graft is packed at the
docking site after the transported segment has docked with the talus. The
docking site is compressed and locked with use of the custom-drilled holes in
the rod before removal of the external fixator
(Fig. 2).
Postoperative Care and Follow-up
Distraction is started between the seventh and the tenth postoperative day.
The rate of the distraction is 1 mm/day, divided into four equal increments.
An epidural catheter is placed for postoperative pain management for five
days, and range-of-motion exercises of the knee are initiated as soon as the
comfort of the patient allows. Full weight-bearing with two crutches is
started immediately.
In the outpatient clinic, patients are screened for signs and symptoms of
local infection. The C-reactive protein level and the erythrocyte
sedimentation rate are monitored serially in patients who have undergone
resection for osteomyelitis. Conventional radiographs are made every two weeks
during the distraction phase and once a month during the consolidation
phase.
The external fixation index is calculated as the duration of external
fixation in months divided by the total amount of bone transported and/or the
amount of lengthening in centimeters.
Six patients treated with the combined technique were followed for a mean
of thirty-four months (range, fourteen to fifty-one months). The mean external
fixation time was 3.5 months (range, two to five months). The mean external
fixator index was 0.57 mo/cm (range, 0.4 to 0.8 mo/cm). Union was achieved in
all patients, and there was no recurrence of infection in the two patients
treated for osteomyelitis (Figs. 3-A, 3-B,
3-C, 3-D, 3-E, 3-F,
3-G, 3-H).
Using the criteria described by Paley et al., we achieved excellent bone
results in all six patients. The functional results were good for four
patients and excellent for two. The scores are shown in
Table I.
We observed four complications, which included three that were categorized
according to Paley as problems (a difficulty that occurs during lengthening
and is resolved without operative intervention) and one that was categorized
as an obstacle (a difficulty that occurs during lengthening and needs
operative treatment). One patient had a minor pin-tract infection, which
resolved with local wound care and antibiotics. One patient had pain during
distraction, which resolved with analgesic medication. One experienced reflex
sympathetic dystrophy after frame removal, which resolved with appropriate
medication and rehabilitation. One patient had irritation at a locking screw,
which was removed under local anesthesia.
Reconstruction after distal tibial bone loss with ankle involvement remains
a therapeutic challenge to orthopaedic surgeons. In order to achieve a stable
plantigrade foot without limb-length discrepancy, various methods have been
used1-16,21-23.
Reconstruction with use of a custom-made endoprosthetic ankle implant in tumor
patients has had a high complication
rate21-23.
Problems with deep infection, talar collapse, and deterioration of function
over time have limited the use of the technique in this group of patients.
Arthrodesis of the ankle has become an accepted method to reconstruct the
ankle
joint1-16.
Moore et al. described reconstruction of the ankle with use of allograft and
arthrodesis with an intramedullary nail following resection of a distal tibial
tumor in nine
patients10.
Allograft fracture and nonunion at the allograft-host junction were problems
in that series. Finally, free tissue transfer either with an osteocutaneous
flap or with a muscle flap followed by the placement of autologous bone graft
has been performed in a small number of patients in centers with microsurgical
capabilities4,11,12.
The use of a circular external fixator has been associated with many
complications often requiring additional surgical
procedures1,3,9,13-15.
Johnson et al. used a circular external fixator as a compressive device to
achieve ankle arthrodesis and deformity correction in a group of six patients
with a rigid valgus deformity and destruction of the
talus3. Union was
achieved in five patients. Four patients had an infection, but it had resolved
at the time of the final followup. One patient had a refracture at the
arthrodesis site. Six wires broke and required reinsertion.
Hawkins et al. used a circular external fixator to achieve arthrodesis and
restore length in ten patients with tibial
osteomyelitis9. All
except one of them achieved union at the arthrodesis site, and only one had 3
cm of residual limb-length discrepancy. Seventeen surgical procedures are done
for frame or pin revisions, additional bone-grafting, corticotomy, or internal
fixation at the tibiotalar joint.
Katsenis et al. performed ankle arthrodesis and limb-lengthening in
twenty-one patients, and all achieved union at the arthrodesis
site1. Two of the
patients had a residual limb-length discrepancy of >2 cm. Seventeen
additional procedures were done, and they included osteotomy, repeat
corticotomy, wire exchange, débridement, bone-grafting, and tarsal
tunnel release.
The problems of a long duration of external fixation, pin-site infection,
and loosening have led many surgeons to search for an alternative method of
ankle arthrodesis when there is structural bone loss. The use of an
intramedullary nail has gained acceptance in achieving an ankle arthrodesis
when there is a substantial amount of bone loss such as occurs in the
treatment of a failed total ankle
replacement6-8,24.
The intramedullary nail provides better stability than conventional screw
fixation. This helps to maintain alignment until union is
achieved25.
The cause of nonunion in ankle arthrodesis is commonly related to problems
of the talus, and traditional screw fixation usually fails because the talus
collapses. Furthermore, the subtalar joint is also frequently involved in
patients with posttraumatic arthritis. Retrograde nail fixation is an
excellent method to achieve a tibiotalocalcaneal
arthrodesis6-8,24,26.
However, it does not correct limb-length discrepancy, and it is
contraindicated in the presence of active infection.
The insertion of an interlocking nail after lengthening or segmental
transport has been done to overcome the problems of shortening, plastic
deformation, and fracture of the regenerated bone following removal of the
circular external fixator. However, it requires an additional operation and
increases the duration of
treatment13. To
overcome this problem, we used bone transport and lengthening over a nail and
had successful results. The technique reduces the external fixation time by
almost half, while not reducing the consolidation index, and it protects the
regenerated bone from plastic deformation and
fracture27,28.
We have also used this method successfully to reconstruct defects following
resection of previously infected bone, but only when the infection had been
eliminated before the procedure was
performed20.
This technique reduces the external fixation time because the external
fixator is removed immediately after the distraction phase. The mean duration
of external fixation in our patients (0.57 mo/cm) was much lower than those
reported by Sakurakichi et al., who used the Ilizarov frame alone (4.8 mo/cm
in the compression-distraction group and 1.18 mo/cm in the bone transport
group)13. Early
removal of the frame also leads to fewer complications. Thus, the
intramedullary rod allows earlier frame removal and provides extra stability
for the reconstruction.
This series is the first, as far as we know, to describe simultaneous
arthrodesis, lengthening, and/or segment transfer with use of the combined
technique. It is a valuable alternative to the classic distal tibial
reconstruction with use of a circular external fixator. Our results are
comparable with other techniques in terms of functional outcome and safety and
are superior in terms of treatment time and external fixator index.
A table showing the evaluation criteria of Paley et al. is available with
the electronic versions of this article, on our web site at
(go to
the article citation and click on "Supplementary Material") and on
our quarterly CD-ROM (call our subscription department, at 781-449-9780, to
order the CD-ROM). ?