“Do you need physiotherapy after hand surgery?”

not always, it will depend on several factors
It sounds like you should be evaluated by a Board-Certified Fellowship-Trained Hand surgeon.
I'd be happy to see you.
please call 413-582-2600 to make an appointment.

I'd recommend therapy, yes. Especially with a certified hand therapist (CHT); it is possible you may only need a few sessions and the therapist provides you with a home exercise program to perform on your own.

Hand therapy is done by occupational therapy but not physical therapy. Therapy should be focused on soft tissue release, the muscle/fascia strain is the precise and exclusive source of pain, tightness, contracture and weakness. NEVER apply stretching or strengthening to an injured soft tissue, otherwise it is irritated and aggravated to worsen. The only effective treatment is done internally by the body itself via light touch precisely on the injured sites to initiate self-healing. All other external treatments are not effective.

That really depends upon what specific kind of surgery you are having. For simple procedures, such as a carpal tunnel release or a trigger finger release, for example, then post-operative therapy is usually not necessary. With more complex procedures, such as a flexor tendon repair, for example, then therapy is quite important. Best you discuss this with your hand surgeon. Good luck.