Arthroscopic thumb carpometacarpal arthroplasty. A, Surface landmarks for D-2 portal. B, Anteroposterior view showing advanced trapeziometacarpal osteoarthritis. C, Arthroscopic view of right thumb from 1-U portal shows the resection (asterisks) in 1-R portal. D, Partial resection of trapezium (Tm). E, Completed hemitrapeziectomy.