1. Division of Neurological Surgery (RFH), University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey; and and the
2. Departments of Orthopaedic Surgery (ARV, TJA, RAB, JMC)
3. Rothman Institute (ARV, JJM, TJA, RAB), Pennsylvania Hospital, Philadelphia, Pennsylvania
4. Neurological Surgery (BEN), Thomas Jefferson University, Jefferson Medical College, Philadelphia, Pennsylvania;