Thirty cases were assessed using the isokinetic machine (Cybex 340) before and after being operated on by the modified Boytchev procedure. All subjects were males ranging in, age from 14 to 36 years (average, 22.5 years.). Eighteen had disorders of the dominant side. Follow-up time was 12 to 41 months (average, 21 months). Peak torque of external and internal rotation power and abduction power were assessed. Rotation power was measured from 60 degrees internal rotation to 60 degrees external rotation at 30 degrees abducted position, and the abduction power was measured from 0 to 120 degrees abduction in the scapular plane. Measurement speeds were 60deg/sec, 180deg/sec, 240deg/sec in each motion. Uninvolved and involved sides were compared before and after surgery except for abduction.The following results were founed;1. External rotationStatistical significance was not seen between uninvolved and involoved side before and after surgery.2. Internal rotationPeak torque of the involved side was lower than univolved side before surgery (p<0.05), but this statistical significance was not seen after surgery.3. AbductionStatistical significance was not seen between uninvolved and involved side after surgery.In our modified Boytchev procedure, the coracoid process is passed through between the joint capsule and the subscapular tendon without detaching the subscapular tendon and it increases the tension of the subscapular tendon. For this reason, we concluded that the modified Boytchev procedure didn't decrease the power of shoulder joint.