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Page 6 of 10 Schaeffer et al. Plast Aesthet Res 2022;9:27 https://dx.doi.org/10.20517/2347-9264.2021.122

Several authors have attempted to compare primary union rates between vascularized bone flaps.
[14]
Lin et al. found no significant difference in the rate of primary union between fibula, rib and iliac crest
[40]
bone flaps (82%, 73.7%, and 75%, respectively). Han et al. were unable to detect a statistically significant
difference between the rate of primary union, rate of overall union, time to union, or return to full activity
following vascularized fibula and iliac crest bone grafts. However, 32% of patients who underwent
vascularized iliac bone graft required a secondary procedure to achieve union, compared to only 17% of
patients following vascularized fibula graft. Secondary procedures included cancellous bone grafting and
[40]
external electrical stimulation followed by cast immobilization .
The time to union of vascularized bone grafts in the setting of lower extremity trauma has been evaluated by
Yazar et al. and Pelissier et al. in single center retrospective reviews. It is reported as an average time to
[13]
[39]
[39]
union for all included vascularized bone grafts (regardless of donor site). Yazar et al. evaluated one-stage
composite bone and soft tissue reconstruction in the setting of lower extremity trauma using fibula (50),
iliac crest (6) and rib (5) vascularized bone grafts. The average time to primary union in this series of 61
patients was 6.9 months, with an average time to overall union of 8.5 months . Pelissier et al. reported a
[39]
[13]
series of 24 patients who underwent vascularized bone grafting (10 iliac crest, 12 fibula, 2 lateral arm flaps),
with an average time to primary union of 11.5 months. Another single center review of 14 patients who
underwent vascularized fibula flap for post-traumatic lower extremity reconstruction reported an average
[45]
time to union of 3.9 months . The average time to union following MFC flaps for all lower extremity
reconstruction is 3.5 months in a systematic review of the literature by Kazmers et al. . However, the
[44]
average time to union in the setting of foot and ankle reconstruction with MFC flap was reported to be 7.1
months in a retrospective review of 30 MFC flaps by Stranix et al. .
[25]
Flap failure
The reported rate of flap failure, defined as unsalvageable vascular thrombosis resulting in total flap loss, in
[39]
the setting of post-traumatic bone defect ranges from 3.1% to 10% (Yazar et al. , 2 of 63 flaps; Lin et al. , 3
[14]
of 68 flaps; Hierner and Wood , 1 of 10 flaps). Higher rates of flap failure following reconstruction for
[19]
chronic osteomyelitis compared to post-traumatic bone defects have been reported - 20.7% (Lin et al. , 6 of
[14]
29 flaps) to 25% flap failure rate (Hierner and Wood , 6 of 24 flaps) .
[19]
[39]
[14]
The rate of flap failure based on donor site was assessed by Lin et al. . Ninety-seven vascularized bone
transfers to the lower extremity from 1991 to 1995 were included for retrospective review. The indications
for bone reconstruction were post-debridement of osteomyelitis and post-traumatic bone defects. The flap
failure rates in this series were 4.7% following fibula flaps, 13.6% following rib flaps, and 27.3% following
iliac bone flaps. Stranix et al. reported no total flap losses in their 30 patient series of MFC flaps for foot
[25]
and ankle reconstruction.

Stress fracture
Stress or fatigue fractures of the vascularized bone graft can occur, especially in lower extremity
reconstruction. Following vascularized bone graft reconstruction, excessive mechanical loading before the
graft has had an opportunity to adequately hypertrophy can result in fracture. The rates of stress fracture
following vascularized fibula grafts for post-traumatic bone defects ranges from 11.5% to 13.1% [14,26,39,43] .
Lin et al. compared the rate of stress fracture following vascularized fibula, rib and iliac bone grafting to
[14]
the lower extremity and found no significant difference (13.1%, 15.8%, and 12.5%, respectively). Two strut
bone constructs had lower rates of stress fracture (6.7% compared to 15.2% for one strut construct);
however, this difference was not statistically significant. No significant association between the length of the
bone graft and the incidence of stress fracture was identified. Of note, indications for bone grafting in this
series included post-traumatic defects and chronic osteomyelitis . Management of stress fractures included
[14]