The effect of concentrated bone marrow
aspirate in operative treatment of fifth
metatarsal stress fractures

Rationale: Fifth metatarsal (MT-V) stress fractures are ill-famed for their long time to union. Even the current gold standard, being operative treatment, does not present optimal results with a mean time to fracture union of grossly 12-18 weeks. The aim of this randomized trial is to study if it is possible to shorten this time to fracture union after operative treatment of MTV
stress fractures with use of concentrated bone marrow aspirate (cBMA).
Objective: To study the effect of using cBMA in the operative treatment of MT-V stress
fractures on the time to fracture healing.
Study design: A prospective, randomized controlled trial.
Study population: Skeletally mature patients with clinically an MT-V stress fracture
Intervention: Every fracture will be treated operatively by intramedullairy screw fixation with an internal bone graft from the decortication along the fracture lines. In the intervention group, a bone marrow aspirate is harvested from the iliac crest during the operation. This aspirate is concentrated and as cBMA put into and around the fracture using the internal decortication as a natural scaffold. The control group will undergo a sham procedure (only a skin wound on the iliac crest) without adding cBMA. Rehabilitation and follow up is the same for both groups.
Main primary endpoints: radiological time to fracture union (in weeks). Main secondary endpoints: clinical time to union (in weeks), time to return to sport and/or work (weeks),
union rate (%), patient function and satisfaction (SF-12, AOFAS, FAAM), complication rate and cost-effectiveness. In laboratory the stage of the stress fractures will be analyzed as well as the composition and osteoprogenitor activity of the cBMA.
Nature and extent of the burden and risks associated with participation, benefit and
group relatedness: Surgery can lead to the common complications of surgery like local hematoma, neurological failure and infection. Possible known risks of collecting cBMA from the iliac crest are hematoma, (temporary) hyper/hypoesthesia, infection, and pain. The only known risk of adding the cBMA at the fracture site is local pain. Participation requires no extra OR time and the intervention could give shorter time to union and time to return to work, sports and activities, also less nonunions and thus potentially a significant decrease in costs.

Operative treatment with additional concentrated bone marrow cells results in better fifth metatarsal stress fracture healing than operative treatment alone. We furthermore hypothesize that composition of bone marrow cells also contributes to healing time.

Baseline visit is pre-operative, the next visit is intra-operative and immediate post-operative. Follow-up will be every 2 weeks, up until the 14th week and, after that, only in the patients in which union has not yet occurred as deemed necessary by the treating physician. Next follow-up visit is at 6 months and the last one is one year after surgery.

All patients will be treated surgically with open reduction and internal fixation with an intramedullairy screw, combined with a decortication and internal bone graft of the fracture site. The rehabilitation protocol for the first 8 weeks after operation is set standard for both intervention and control group; first two weeks non weight bearing-cast, than 2 weeks partial weight bearing cast, thereafter 4 weeks in a weight bearing cast or walker.
On every patient in the intervention group, a bone marrow draw is performed by the
orthopaedic surgeon while under anaesthesia in the OR, through needle aspiration from patient’s own iliac crest. The cells are concentrated by utilizing MarrowStim Concentration System (Biomet) which centrifuges the cells into an efficient concentration of autologous bone marrow aspirate (cBMA). This cBMA is added to the fracture together with the internal bone graft. In the control group only a skin inciscion at the iliac crest is performed (sham procedure to ensure blinding)