• Orthopaedic Procedures
• Hip & Knee Conditions
• Orthopaedics Clinical Trials

• Orthopaedic Procedures
• Hip & Knee Conditions
• Orthopaedics Clinical Trials
• Orthopaedics

According to a study reported by Martinus Richter, MD, Hospital Rummelsberg, Schwarzenbruck, Germany, matrix-associated stem cell transplantation (MAST) is a safe and effective method for the treatment of chondral defects of the foot and ankle. Its main advantage is that it requires only a single procedure.

MAST is a modified version of matrix-induced autologous chondrocyte implantation (ACI) that allows for implantation of a potentially higher concentration of stem cells [Richter M, Zech S. Foot Ankle Surg. 2013]. For this open surgical procedure, stem cell-rich blood (about 3% stem cells) is harvested from pelvic bone marrow and centrifuged at 1500 revolutions per minute to double the concentration of stem cells. The resulting cells are implanted via microfracturing or bone transplantation in the case of a defect that is deeper than 5 mm, through a collagen matrix impregnated with the stem cell and fibrin glue. Motion is permitted 3 days postsurgery. Postoperative treatment includes 15 kg of partial weight bearing for 6 weeks.

In this more recent prospective study, surgeons determined 75 consecutive patients (78 defects) to be eligible for MAST based on initial arthroscopy. All procedures took place between April 2009 and September 2011. Defect size, procedural time, and Visual Analogue Scale Foot and Ankle (VAS-FA) score were recorded. Patients were followed for 2 years. There was no control group.

Patients (mean age, 34 years; range, 16 to 64; 72% men) had a mean baseline VAS-FA score of 50.2 out of 100 (range, 24.3 to 68.4). Medial and lateral talar shoulders were the most common defect sites (28 patients each), followed by defects of the metatarsophalangeal joint 1 head (10 patients). Of the remaining 9 patients, 3 had defects of the medial and lateral shoulders; 3 had defects of the tibia; and 3 had defects of the calcaneus. The mean defect size was 1.1 cm² (range, 0.2 to 6); mean procedural time was 15.4 minutes (range, 5 to 38). Autologous bone graft was used in 3 cases. More than 300 additional procedures were performed at the time of MAST. All patients returned to work after an average of 6 weeks. At 24 months, mean VAS-FA scores were significantly (P = .01) increased (mean, 94.5; range, 73.4 to 100), and no complications were reported.

The results of this study indicate that MAST is safe and associated with good outcomes in patients with chondral defects of the ankle or foot. An important advantage over other approaches is that it can be accomplished with 1 procedure (vs ACI or matrix-induced ACI, which requires 2 procedures). Whether MAST is superior to other available procedures—such as debridement, microfracturing, or abrasion; use of a matrix without cells; or other available cells—is not known. How the result with MAST might compare to the use of “real” stem cells is also not known. Prof Richter concluded that MAST is “just one single step forward.” Prospective randomized studies are needed to compare these methodologies.

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