hmmm tricky one! I don't know what type of equipment that you have access to:how about the
Tricep Rope Pressdown
Facing a high-cable pulley machine, stand with your feet hip-width apart and knees slightly bent.
Grasp the ends of the ropes attached to a high-cable pulley, palms facing each other. Hold elbows close to body at waist level.
Without altering elbow position, press your arms down until hands drift apart and palms face behind you.
Return to starting position and repeat.
I'm going over in my head all kinds of tricep workouts like

ullover-and-Presses
Reverse-Grip Bench Presses
Dips between Benches
One-Arm Dumbbell Triceps Extensions
Two-Dumbbell Triceps Extensions
Power Pushdowns
Reverse Pulley Pushdowns
One-Arm Pulley Pushdowns
Incline Cable Triceps Extensions
High-Pulley, Long-Cable Triceps Extensions
Kneeling High-Pulley, Long-Cable Triceps Extensions
One-Arm, High-Pulley, Long-Cable Triceps Extensions
Barbell Triceps Kickbacks
Dumbbell Triceps Kickbacks
One-Arm Cable Triceps Kickbacks and the rope press down is the best I could come up with that won't put too much strain on you!hmmm!The last and probably easiest way to go would be a quick combo of an alternating bicep curl with a tricep extension on the down motion working both sides evenly at a faster pace to work the tri but it won't be a full range of movement and be less stressful! hope this helped!Your friend in fitness~~Francine