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Patient age is also an important consideration. Traumatic bone defects in the pediatric population are more
rare and have better prognoses compared to the adult population. The integrity of their relatively thick,
vascular, and cellularly active periosteum can be used to guide the reconstruction of pediatric traumatic
bone defects. If the periosteum is intact, bone reconstruction may not be necessary with appropriate
stabilization. A non-vascularized autograft may be used for bone defects with partially intact periosteum. In
patients with no periosteum or with nonunion due to infection, bony reconstruction using the induced
membrane technique followed by autograft bone, bone transport, or vascularized bone grafting has been
described. Case series describing outcomes following reconstruction of pediatric bone defects in the setting
of trauma are limited . However, the use of vascularized bone grafts in the pediatric population has been
[32]
shown to be a reliable reconstructive option following tumor resections of the extremities with flap survival
rates of over 92%-92% for fibula, 100% for iliac crest, and 96% for MFC flaps [33-36] . Long-term outcomes
following vascularized fibula flaps for bone sarcoma reconstruction in pediatric patients were evaluated by
[37]
Ruiz-Moya et al. and Ghoneimyet al. . In these series (68 patients total), the rate of graft fracture was
[38]
33.3% to 34%, and the rate of non-union was 11% to 13.8% [37,38] .

DEFECT RECONSTRUCTION
Following vascularized bone graft harvest and recipient site preparation, the bone graft is inset to bridge the
bony defect, and the flap is revascularized. Several options have been described in the literature for graft
stabilization including plates and screws, screws only, k-wire fixation, intramedullary nail, press-fit (MFC
flaps), and external fixation [3,18,25,39,40] . Stability can also be augmented with graft inset into the medullary
canal of the recipient bone . Many authors advocate for ancillary cancellous bone graft placement at the
[18]
[40]
junction between the graft and the recipient bone has been to accelerate healing [18,40] . Han et al. compared
vascularized bone graft fixation techniques (stable internal fixation vs. unstable internal fixation vs. external
fixation). They reported significantly higher rates of primary bone union with stable internal fixation ±
ancillary bone grafting (71%) compared to external fixation ± ancillary bone grafting (47%). The type of
skeletal fixation with or without ancillary bone grafting had no significant effect on overall bone union
[40]
rates . Many authors describe a preference for stabilization with Ilizarov frames - the reported advantages
include the ability to adjust bone compression/distraction, early weight-bearing, and decreased risk of
infection with an external device [3,41] . The use of large plates for fixation can provide too rigid fixation ,
which can result in a stress-shielding effect on the bone graft [18,42] .

OUTCOMES
Bone union
Osseous union is an indicator of bone healing. This can be assessed using plain film radiographs to evaluate
for the presence of a bridging callus or absence of the fracture line. Reported rates of primary union for
vascularized bone grafting in the post-traumatic setting range from 79% to 88.5% (Minami et al. , 26 of 33
[43]
flaps; Yazar et al. , 54 of 61 flaps) [39,43] . Han et al. evaluated vascularized bone grafting with the fibula and
[39]
[40]
iliac crest flaps to all skeletal defects (mandible, clavicle, upper extremity, pelvis, lower extremity). They
reported significantly lower rates of primary and overall union in patients with osteomyelitis - 46% (29 of 60
flaps) rate of primary union, 76% (46 of 60 flaps) rate of overall union . In a systematic review by
[40]
Kazmers et al. in 2018, MFC flaps performed for talus avascular necrosis and nonunion had an 86% union
[44]
rate (6 of 7 flaps), while flaps performed for navicular avascular necrosis (2 patients) had a 100% union rate.
[25]
Stranix et al. reported a series of 30 MFC flaps for foot and ankle reconstruction with a primary union
rate of 74% and overall union rate of 89% - of note, the etiology of hindfoot pathology was a history of
trauma in 73% of these patients.