If you train Brazilian Jiu Jitsu, with the gi (kimono) regularly, the chances of you having problems with the joints in your fingers at any given point is almost 100% certain. Although it is wise to give the joint time to heal, some of us, the stubborn ones, rather insist on training, aggravating the problem.
The swelling of the joints is caused by the trauma of repeatedly pushing your your joints to the max, with constant pressure, impact and tugging which can result in having hands like the ones depicted on the banner (which belong to Paulo Miyao). There have been many studies regarding the subject of swollen finger joints in grappling, including in other sports such as Judo.
This is a simple yet effective way to control the movement of your fingers containing the damaged joint, but it can also be used to fortify your grip when you are injury free. The trick is to use a good quality athletic tape; much like the tape you see footballers and Rugby players use to tape their ankles and wrists, which should be available at specialist pharmacies.
The example shown here in this Gracie Jiu Jitsu video, with the “X” shape finger taping is helpful, but the same effect can be drawn from taping circles around the phalanges bones, one around the proximal phalanges, another in the medial phalanges and another in the distal phalanges (distal phalanges is not always necessary depending on the damage on the finger). Also, even though you might have only one finger injured we advise you to tape at least the two fingers next to the damaged one in order to fortify the whole hand.
You will find that with this your grip will be stronger and there will be a lot less pressure on the joints.