Reconstruction of the distal end of the tibia in a patient with an unstable
ankle joint, bone loss, and/or limb-length discrepancy is a challenging task
for the orthopaedic surgeon. The use of a circular external fixator alone to
achieve ankle arthrodesis was initially described to overcome the complicating
problems of infection, deformity, bone loss, limb-length discrepancy, and/or
osteoporotic
bone1-17.
Nevertheless, the utilization of circular external fixators has been
associated with many
complications4.
Pin-site infection, refracture, nonunion, malunion, and loss of alignment have
been reported in many
series1,2,10,13-17.
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 limb-lengthening in selected patients.
This technique allows for earlier fixator removal, and the intramedullary nail
prevents loss of lengthening, angulation, and refracture.
In patients with chronic osteomyelitis, the operative procedure is
performed in two stages as described by Kocaoglu et
al.1. In those
patients, radical débridement with bone resection is performed during
the first stage. In all other patients, all procedures are performed during
the same operative session.
In patients with chronic osteomyelitis, hardware removal and radical
resection of dead bone with débridement of the infected, scarred soft
tissue is performed and representative tissue specimens, including those from
sinus tracts communicating with dead bone, are obtained for culture. The dead
space is filled with custom-made antibiotic-impregnated
polymethyl-methacrylate beads (a combination of 2.4 g of teicoplanin or 2 g of
vancomycin and 40 g of polymethylmethacrylate powder). Stabilization is
achieved with a temporary external fixator. Small soft-tissue defects
resulting from débridement of infected soft tissues and fistulae,
ranging in diameter from 2 to 3 cm, are closed by means of acute shortening.
In patients with larger soft-tissue defects, free myocutaneous (latissimus
dorsi) flaps are utilized (Figs. 1-A
through 1-D).
The secondary reconstructive procedure is performed under tourniquet
control with the patient in a supine position on a radiolucent operating
table. Initially, the subtalar joint (and the ankle joint when it is also
unstable) is prepared for arthrodesis through a small incision over the sinus
tarsi or through a distal fibular osteotomy
(Fig. 2). The foot is
positioned in correct alignment (neutral to 5° of dorsiflexion in the
sagittal plane, 5° of valgus in the frontal plane, and 5° of external
rotation in the axial plane) for ankle arthrodesis. A threaded Kirschner wire
is inserted through the plantar aspect of the calcaneus, and the entry point
for intramedullary nail insertion (a projection through the middle of the
distal tibial joint line in the frontal plane and the middle to anterior third
of the distal tibial joint line in the sagittal plane) is determined with an
image intensifier (Fig. 3). A
cannulated drill is then percutaneously inserted over the Kirschner wire to
enlarge the hole for the insertion of a guidewire. After preparation of the
appropriate entry site, reaming is performed over a guidewire in 0.5-mm
increments.
Additional holes are predrilled in the nail at the anticipated site of
locking of the segment at the completion of bone transport to prevent recoil
of the segment (Figs. 4-A, 4-B, and
4-C). The levels of the extra holes are determined with use of
intramedullary nail templates on standing radiographs, both of which have the
same scale of magnification (Figs. 4-A and
4-B). Next, a corticotomy is performed at the appropriate level
(Fig. 5) with use of a Gigli
saw. In cases involving lengthening, the level of corticotomy is calculated so
that a proximal bone segment of at least 6 to 8 cm remains at the end of
lengthening.
After the medullary canal is overreamed 2 mm larger than the planned size,
the intramedullary nail is inserted and the distal part is locked with use of
the targeting device of the nail (Figs. 6-A
and 6-B). In bone-segment transfers both ends of the nail are
locked, and in lengthening cases only the distal end is locked. The proximal
holes are locked with use of a freehand technique. The distal part of the
fibula is fixed to the tibia with two headless compression screws (Acutrak) to
augment the arthrodesis site. In patients with paralytic feet, the
talonavicular and calcaneocuboid joints are prepared for arthrodesis by means
of mini-incisions and débridement with a high-speed burr under
image-intensifier control, and osteosynthesis is again achieved with headless
compression screws or 6.5-mm cannulated screws
(Fig. 7).
The circular external fixator construct is prepared preoperatively on the
basis of biplanar radiographs.
In cases of lengthening, two circular rings are assembled at the proximal
part of the tibia, two rings are assembled distal to the osteotomy site, and
one foot frame is placed at the foot. The arthrodesis site is packed with
autologous cancellous bone graft taken from the iliac crest, and compression
is accomplished with use of the ring external fixator. The circular frames are
removed after the lengthening has been completed. The locking screws are then
inserted at the proximal part of the tibia and the lengthened segment
(Figs. 8-A through 8-F).
In cases involving a segment transfer, three circular rings are assembled
at the proximal part of the tibia. One ring, connected with the foot frame
distally, acts as a transport segment. 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 through the custom-made hole in the
intramedullary nail before removal of the external fixator
(Figs. 9-A, 9-B, and 9-C).
Distraction is started between the seventh and tenth postoperative days.
The rate of distraction is 1 mm per 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
patient's comfort level allows. Full weight-bearing with two crutches is
started immediately.
In the outpatient clinic, patients are screened for local signs and
symptoms of infection. The C-reactive protein level and the erythrocyte
sedimentation rate are monitored serially in patients who have had a resection
for the treatment of osteomyelitis. Conventional radiographs are made every
two weeks during the distraction phase and once a month during the
consolidation phase.
CRITICAL CONCEPTSINDICATIONS:An unstable ankle joint (with bone loss) and a limb-length discrepancy due
to such conditions as Charcot arthropathy, poliomyelitis, arthropathy, or
sciatic nerve damageBone loss to within 1 cm of the articular surface of the distal part of the
tibia and/or talus, complicated by infection, limb-length discrepancy, or
deformity resulting from previous trauma, chronic osteomyelitis, or tumor
resectionBone loss due to débridement following infection at the site of a
total ankle arthroplastyCONTRAINDICATIONS:Chronic osteomyelitis in a C host according to the Cierny-Mader
classification systemSevere prior vascular damage (pathologic flow in both the tibialis
posterior and dorsalis pedis arteries) as demonstrated by preoperative Doppler
ultrasonographyAn absent calcaneus resulting from trauma, tumor, or infectionA noncompliant patientPITFALLS:In cases of infection, failure to achieve infection-free margins following
radical débridementFailure to achieve healthy soft-tissue coverage following radical
débridementFailure to precisely determine the length and diameter of the
intramedullary nail to be inserted and the level and number of custom locking
holes with the preoperative use of templates and standing radiographs
(Figs. 4-A, 4-B, and 4-C)Failure to overream the medullary canal by 2 mm larger than the diameter of
the intramedullary nail to ensure easy gliding of bone segments over the
nailFailure to ensure that the inserted Schanz screws or Kirschner wires are at
least 1 mm away from the intramedullary nailFailure to place the external fixator parallel to the intramedullary nail
in both the frontal and sagittal planesFailure to add a talonavicular (and calcaneocuboid) arthrodesis in an
unstable, paralyzed footAUTHOR UPDATE:Recently, for patients needing ankle arthrodesis in conjunction with
segmental transfer and lengthening of the tibia, a substantially longer
intramedullary nail has been utilized and initially left proud proximally. For
those patients, the external fixator frame is temporarily extended proximally
to include the distal portion of the femur. When the intramedullary nail
glides sufficiently distal to free the knee joint during lengthening, the part
of the frame that transfixes the knee joint is removed and physical therapy is
initiated (Figs. 9-A, 9-B, and
9-C).
CRITICAL CONCEPTS
INDICATIONS:
An unstable ankle joint (with bone loss) and a limb-length discrepancy due
to such conditions as Charcot arthropathy, poliomyelitis, arthropathy, or
sciatic nerve damageBone loss to within 1 cm of the articular surface of the distal part of the
tibia and/or talus, complicated by infection, limb-length discrepancy, or
deformity resulting from previous trauma, chronic osteomyelitis, or tumor
resectionBone loss due to débridement following infection at the site of a
total ankle arthroplasty
An unstable ankle joint (with bone loss) and a limb-length discrepancy due
to such conditions as Charcot arthropathy, poliomyelitis, arthropathy, or
sciatic nerve damage
Bone loss to within 1 cm of the articular surface of the distal part of the
tibia and/or talus, complicated by infection, limb-length discrepancy, or
deformity resulting from previous trauma, chronic osteomyelitis, or tumor
resection
Bone loss due to débridement following infection at the site of a
total ankle arthroplasty
CONTRAINDICATIONS:
Chronic osteomyelitis in a C host according to the Cierny-Mader
classification systemSevere prior vascular damage (pathologic flow in both the tibialis
posterior and dorsalis pedis arteries) as demonstrated by preoperative Doppler
ultrasonographyAn absent calcaneus resulting from trauma, tumor, or infectionA noncompliant patient
Chronic osteomyelitis in a C host according to the Cierny-Mader
classification system
Severe prior vascular damage (pathologic flow in both the tibialis
posterior and dorsalis pedis arteries) as demonstrated by preoperative Doppler
ultrasonography
An absent calcaneus resulting from trauma, tumor, or infection
A noncompliant patient
PITFALLS:
In cases of infection, failure to achieve infection-free margins following
radical débridementFailure to achieve healthy soft-tissue coverage following radical
débridementFailure to precisely determine the length and diameter of the
intramedullary nail to be inserted and the level and number of custom locking
holes with the preoperative use of templates and standing radiographs
(Figs. 4-A, 4-B, and 4-C)Failure to overream the medullary canal by 2 mm larger than the diameter of
the intramedullary nail to ensure easy gliding of bone segments over the
nailFailure to ensure that the inserted Schanz screws or Kirschner wires are at
least 1 mm away from the intramedullary nailFailure to place the external fixator parallel to the intramedullary nail
in both the frontal and sagittal planesFailure to add a talonavicular (and calcaneocuboid) arthrodesis in an
unstable, paralyzed foot
In cases of infection, failure to achieve infection-free margins following
radical débridement
Failure to achieve healthy soft-tissue coverage following radical
débridement
Failure to precisely determine the length and diameter of the
intramedullary nail to be inserted and the level and number of custom locking
holes with the preoperative use of templates and standing radiographs
(Figs. 4-A, 4-B, and 4-C)
Failure to overream the medullary canal by 2 mm larger than the diameter of
the intramedullary nail to ensure easy gliding of bone segments over the
nail
Failure to ensure that the inserted Schanz screws or Kirschner wires are at
least 1 mm away from the intramedullary nail
Failure to place the external fixator parallel to the intramedullary nail
in both the frontal and sagittal planes
Failure to add a talonavicular (and calcaneocuboid) arthrodesis in an
unstable, paralyzed foot
AUTHOR UPDATE:
Recently, for patients needing ankle arthrodesis in conjunction with
segmental transfer and lengthening of the tibia, a substantially longer
intramedullary nail has been utilized and initially left proud proximally. For
those patients, the external fixator frame is temporarily extended proximally
to include the distal portion of the femur. When the intramedullary nail
glides sufficiently distal to free the knee joint during lengthening, the part
of the frame that transfixes the knee joint is removed and physical therapy is
initiated (Figs. 9-A, 9-B, and
9-C).