At the time of surgery, all patients will undergo standard ankle arthroscopy with debridement and microfracture of the OLT. If randomized to the microfracture alone group, no further intervention will take place. If randomized to the microfracture + BMAC group, then, while the surgeon is performing the ankle arthroscopy, the surgical assistant will perform the iliac crest bone marrow aspiration. The ipsilateral iliac crest will undergo sterile preparation and draped into the surgical field. The iliac crest aspiration site will be injected with 2cc of 1% lidocaine for postoperative pain control. Through an approximate 4mm incision, approximately 2 cm posterior to the patient's ipsilateral anterior superior iliac spine, a Jamshidi® type trocar/cannula system will be placed through the incision and the medial and lateral borders of the pelvic brim will be palpated. Once centered, the needle will be malleted into the pelvis between the inner and outer tables to a depth of 2-3 cm. The sharp trocar will be switched for the blunt trocar and introduced another 2-3cm. The blunt trocar is used to prevent penetration of the cannula through the inner table cortex. Next, 60cc of iliac crest bone marrow will be aspirated. The needle will be withdrawn and the incision is closed with one 3-0 nylon suture. The iliac crest bone marrow aspirate is then passed through a filter to remove any bone spicules and then centrifuged using the Harvest SmartPReP 2 BMAC system (http://www.harvesttech.com). This device is approved for intra-operative point-of-care use for concentrating iliac crest bone marrow. Its use is approved at Duke. The process takes approximately 15 minutes and will be occurring simultaneous to the ankle arthroscopy, debridement, and microfracture of the OLT. Concentration of 60cc of iliac crest bone marrow aspirate typically yields 6-7cc of BMAC. Therefore, to provide a standard amount of BMAC across all cases, 5cc of the BMAC will be injected into the ankle joint through the arthroscopy incision prior to closure.