Mark,
You didn't mention what camera you are using or what format you are shooting. Perhaps a different camera would help. The Linhof Technikardan is one possibility. It has exactly three knobs. Two small knobs on the left side (your uninjured hand) are loosened/tightened to extend the rail for long lenses. The only other knob, and the only one on the right side, is the focusing knob. The function of this knob is very smooth and doesn't require much force to operate. The focus, and all other movements, are locked using levers. For this reason, I found the TK45S very easy to use in cold weather with gloves on and/or numb fingers. Sounds like it might also be a good match for your needs.
As Jorge mentioned, butterfly or T-Knobs require less force to tighten/loosen than knurled round knobs. Some cameras that use primarily T-Knobs and levers are the Canham and Phillips brands. The Canham DLC (and larger metal models) use a knob for focusing (low force) and for front and rear shifts. All other movements (rear tilt and swing, front rise/fall, tilt and swing) all use either T-Knobs or levers to tighten/loosen.
Another possible option is a camera that uses self-locking geared movements. This assumes that it's the force required to loosen/tighten the controls, and not merely the act of turning a knob that aggravates your condition. The ARCA-SWISS Monolith uses self-locking geared movements for all movements (but it's a heavy camera better suited to studio use). The F-Line Metric models use self-locking greared movements for front and rear shit and rise/fall. You can also add the Micrometric Orbix for self-locking gear driven front tilt. The front and rear focus locks still use knobs. In the standard configuration, these knobs are on the right, but I believe the camera can be re-configured to place the focusing controls and locking knobs on the left side of the rail. Also, the ARCA-SWISS knobs have rubber grips and are easier on the hands than most other bare metal knobs.
If you could get to a dealer or show where multiple cameras are present (Linhof, ARCA-SWISS, Canham) you could try them in person and see which work the best for you. It's hard for others to make specific recommendations as we don't know exactly how much torque/force you can apply before triggering the pain you are experiencing. This is truly a case where try-before-you-buy would be the best course of action if at all possible.
There are probably other cameras that don't rely entirely on knobs, but I can't think of any off the top of my head.
Kerry