An adjustable prosthetic socket includes proximal and distal ends and an axis extending between the proximal and distal ends. A distal base is adapted to support a distal portion of a residual limb and is located at the distal end of the socket. First and second spines extend upward from the distal base that define at least part of a circumference of the socket about the axis. A proximal support is connected to the second spine and arranged to distribute pressure from the second spine over a portion of the residual limb. A tensioning system is operatively connected to the first and second spines and arranged to selectively adjust the circumference of the socket. The tensioning system includes a dial tensioner connected to the first spine.