Only DIP and PIP joints affect TT excursion; hence these are the main joints to be immobilized to protect TT repair. The middle finger TT showed the least tolerance to lengthening with potential for mallet deformity. Joint flexion deformity is proportional to tendon lengthening. Only 1 mm of TT lengthening results in approximately 25 degrees of DIP joint extension lag, and 4 mm of TT lengthening results in DIP joint flexion deformity greater than 60 degrees . Even 1 mm of TT shortening will seriously restrict DIP joint flexion.