Introduction: Hand and wrist stability are critical for optimal upper extremity function. Instability occurs when injury or a pathological condition alters balance, typically in the
basketball players and handball players. Injury also can occur whenever the ligaments are subjected to tensile forces that exceed their physiological capacities. For example, thumb is stable in extension when ulnar collateral ligament sprain or tear and gamekeepers thumb injury happen but it appears to be unstable inflexion. The goal was to decrease this injury to a region.
Materials and Methods:
Precise hand positioning on 5 Basketball is drawn for guides to teach proper shooting technique by using Morley theorem proof results (figure1). Lemma: if points ź. y. z. ý follow conditions: zý   = zy = yź.  ŷzý = ẑ́yz = π − 2α > ^π then will be located on a
circle. Circleaýzyź is as a Basketball and points are as Head of distal phalanges. If angle size between finger number 1 and finger number 2 and finger number 5 equals3α , this size between finger number 2 and finger number 3 and between finger number 3 and finger number 4 equals2α , It is same for between finger number 4 and finger number 5; as a result, force that comes from the Basketball brings the least damage in the fingers and thumb.
Results: The alpha angle size is different in Athletes; but according to the theorem, it must be less than^π. Our Studies have found alpha angle normal size (about15°) and relation between alpha angle size and Distance between fingers in basketball players follow: sin (^π −  α) +3 1


 sin(π−α)3. When the alpha equals 15, the equation is 2.12 cm, by considering this result shooting range increase and damages is in lowest point.

 Conclusion Results also can be used in evaluations. ligament laxity maybe reduced by using Mathematical model.