Keywords Fibula - Lower extremity - Pedicled flaps - Tibial defect
INTRODUCTION
Various techniques have been described for tibial reconstruction; however, reconstruction
of post-traumatic composite tibial and soft tissue defects remains challenging. A
fibular free flap is currently considered the standard treatment for tibial defects
> 6 cm [1 ]. However, in cases where the contralateral fibula cannot be used, an ipsilateral
fibular transfer is the alternative, although it can lead to further limb instability
[1 ]
[2 ]
[3 ]
[4 ]. We report an unusual case, wherein a composite tibial defect was reconstructed
with ipsilateral fractured fibular segments and a bipedicled flap, in a patient who
had lost the contralateral leg due to above-knee amputation performed for a severe
crush injury.
CASE
A 38-year-old man sustained injuries in both lower extremities in a motor vehicle
accident. Bilateral closed femoral shaft fractures were present, along with bilateral
tibio-fibular fractures and severe soft tissue injury. The right leg was amputated
at the above-knee level on an emergent basis, due to extensive comminution and loss
of circulation caused by the crush injury. The bilateral femoral shaft fractures were
fixed with plates. Reduction and external fixation of the left tibia was performed
along with titanium plating. Initially, the size of the soft tissue defect was 20
× 15 cm, and the fractured tibial segments were exposed. The patient was treated in
the emergency intensive care unit for 2 weeks due to multiple rib fractures and hemothorax.
A bacterial culture from the tibial defect site revealed the presence of Pseudomonas aeruginosa . Wound care was performed with betadine, saline solution irrigation, and betadine-soaked
dressings. The patient was shifted to the general ward 2 weeks after the trauma, at
which time debridement and ostectomy of the necrotic tibia were performed. The tibial
defect measured 17 cm. A vascularized bone graft was required to reconstruct the tibia;
however, the contralateral fibula was lost due to the trauma and the ipsilateral fibula
had multiple segmental fractures. We conserved the defect by external fixation of
the tibia until complete union of the fractured fibula was achieved.
The P. aeruginosa infection did not resolve despite intravenous antibiotic injections and debridement.
The patient was transferred to the isolation ward due to neutropenic fever, 7 weeks
after the trauma. Carbapenem and other analgesics that were assumed to have caused
the neutropenic fever were discontinued. After 1 week of observation, the patient
returned to the general ward. Thorough sterile irrigation and dressing, as well as
debridement, were performed under general anesthesia twice in order to eradicate P. aeruginosa without antibiotics. During the conservative management period, union of the fractured
fibula was observed on serial follow-up radiographs.
Four months after the trauma, decrease of P. aeruginosa was observed in wound culture from a 20 × 15 cm skin defect, and a united fibula
was noted on radiography ([Fig. 1 ]). We reconstructed the tibial defect using the ipsilateral fibula, including the
united fracture segments.
Fig. 1. Four months post-trauma. A 20×15 cm soft tissue defect can be seen.
First, computed tomography angiography was performed before surgery to check whether
the three main arteries of the lower extremities were intact. The fibula was approached
through a curvilinear posterior incision. The lateral head of the gastrocnemius was
mobilized from the distal femur and the soleus was stripped from its origin from the
posterior aspect of the fibula and the interosseus membrane. The popliteal vessels
were dissected distally to the tibial vessels and the peroneal artery, which supplied
the pedicle to the fibula. The fibula was completely exposed and ostectomy was done
containing the flexor hallucis longus muscle and the peroneal artery. The 17-cm vascularized
fibular flap was transposed through the intermuscular septum. After the transposition
of the vascularized fibular flap, a bipedicled flap was transposed from the medial
to the anterior side to cover the area of bone exposure. The harvested fibula was
affixed to the tibial defect site using a plate and the external fixator system was
maintained for stable alignment of the tibia ([Fig. 2 ]). The size of the soft tissue defect was 20 × 15 cm, and it was covered with the
bipedicled skin flap.
Fig. 2. The fractured fibula was transferred medially to bridge the tibial defect. (A) Clinical
photography. (B) Immediate postoperative X-ray.
Two months after surgery, the flap was stable and bony callus formation was observed
on radiography. The patient started non-weight-bearing and muscle-strengthening exercises
of the left lower leg. Three months postoperatively, hypertrophy of the transferred
fibula and complete healing of the femur was observed on radiography. Weight-bearing
training was started with a lower limb prosthesis on the amputated side. The patient
learned to take steps with the prosthesis and the reconstructed lower leg with the
help of a walker. Two weeks after the start of weight-bearing exercises, the patient
had a fracture in the tibia at the weak point of the proximal plate fixation site.
After confirming fracture union, weight-bearing training was restarted with a walker.
Subsequently, the patient began to ambulate independently without the walker and returned
to routine activities 6 weeks after the second tibial fracture. Two years postoperatively,
good bony union and fibular hypertrophy were observed ([Fig. 3 ]). We confirmed the patient’s satisfaction in performing daily living activities
with the reconstructed leg at a 12-year follow-up ([Fig. 4 ]).
Fig. 3. Two years postoperatively, good bony union and fibular hypertrophy were achieved.
(A) X-ray photography. (B) Anteroposterior photograph of the left lower limb showing
weight-bearing ability.
Fig. 4. Twelve years postoperatively, good bony union and fibular hypertrophy were maintained.
(A) X-ray photography. (B) Anteroposterior photograph of the left lower limb showing
weight-bearing ability.
DISCUSSION
There are various methods to reconstruct bone defects, such as direct bone grafting,
bone transport using the Ilizarov lengthening technique, and using vascularized bone
grafts [1 ]
[5 ]
[6 ]
[7 ]. Bone grafts with an independent vascular supply demonstrate reliable osteoinductive,
osteoconductive, and osteoprogenitor activities [4 ]. The contralateral untraumatized fibula is an ideal donor site for a vascularized
bone graft; however, in cases where microsurgery is not feasible, the ipsilateral
fibula is an alternative [2 ]. In our case, it was not possible to obtain a graft from the contralateral fibula
due to the severe crush injury. A previous study reported that united fibular segments
were used to reconstruct the defect in cases of associated fibular fractures [8 ]. In our case, the fractured segments united while we waited for the patient’s general
condition to improve and for eradication of the P. aeruginosa infection. Therefore, we decided to use the ipsilateral fractured segments. However,
we were uncertain of the ability of the fractured segments to bear weight without
the contralateral leg. Some studies have reported that an ipsilateral fibular graft
may result in the loss of supplementary mechanical support of the tibial graft, thereby
increasing limb instability [4 ]
[9 ]. We managed the issue of instability by using a brace and prosthesis on the contralateral
limb along with a cautious rehabilitation schedule.
Dissection of the fibula while preserving the vasculature is more challenging in a
traumatized lower leg than in untraumatized tissue. Moreover, the procedure becomes
more difficult in cases of fibular fracture. A study reported that dissection was
easier in united fractures than in non-united fractures [8 ]. In our case, there was sufficient time for union of the fractured fibula.
Previous studies reported that the average time for bony union in a vascularized fibular
graft was 3 to 6 months [4 ]
[8 ]. In the present case, callus formation was observed 2 months after surgery and fibular
hypertrophy was observed after 3 months. Considering the overwhelming stress on the
unilateral reconstructed tibia, we gradually initiated weight-bearing exercises for
the patient. The patient required sufficient time to familiarize himself with walking
using the prosthesis and the reconstructed limb.
A review of the literature on vascularized fibular grafts revealed that the stress
fracture rate following complete union was 20% to 60% [4 ]
[5 ]. In our case, a pure stress fracture occurred 2 weeks after initiation of weight-bearing
training. The height and body weight of our patient were 178 cm and 89 kg, respectively.
Bone alignment was maintained through internal fixation. External fixation could be
problematic for infection and rehabilitation treatment, and intramedullary fixation
was not used because it could cause problems with blood circulation and stability
of the fibular flap. Nevertheless, a stress fracture occurred, which was thought to
be because the prosthetic leg and surgical site were not sufficient to support the
weight of 89 kg due to the contralateral amputation. Therefore, when the same operation
is performed in the future, it is considered to be preferable to delay the start of
rehabilitation, unlike the protocol for fibular flaps in general. Although we started
rehabilitation gradually, the stress from the patient’s body weight caused the fracture.
The fracture was managed with a long-leg cast for 6 weeks.
By reporting this case, we have highlighted an unusual scenario of unilateral limb
weight-bearing, wherein we were able to salvage the sole lower extremity by the ipsilateral
fractured fibula transfer and a bipedicled skin flap.
NOTES
Ethical approval
The study was approved by the Institutional Review Board of Wonju Severance Christian
Hospital (IRB No. CR321315) and performed in accordance with the principles of the
Declaration of Helsinki. Written informed consent was obtained.
Patient consent
The patient provided written informed consent for the publication and the use of his
images.
Author contribution
Conceptualization: J Kim. Data curation: SW Kim, ES Kim. Visualization: SW Kim, ES
Kim, CE Yang, J Kim. Writing - original draft: ES Kim. Writing - review & editing:
SW Kim, ES Kim. All authors read and approved the final manuscript.
