Chapter 1: risk factors for DIP subluxation after a mallet fracture. Fragment size, fragment displacement, and interval between injury and treatment were associated with initial and late subluxation in mallet fractures. For each 1% increase in total articular surface involvement in fractures with more than 39% involvement, the risk of subluxation increased by 4% and for each 1% of displacement, the risk of subluxation increased by 4%. Concluding that fragment displacement also could play a role in the decision making for surgical treatment. Chapter 2: we found that mallet fractures of the thumb presented for treatment sooner after injury, had less fragment displacement, and less articular involvement compared to mallet fractures of others fingers. None of the mallet fractures of the thumb had radiographic evidence of subluxation, whereas 25% of mallet fractures of other fingers had initial or later subluxation. Chapter 3: We wanted to study the factors associated with subluxation of the PIP joint and to calculate a threshold value of the fragment size and fragment displacement associated with subluxation. We found moderate to substantial agreement between hand surgeons on subluxation and an overall percent agreement of 85%. Fragment size of 35% had a specificity of 90% and a NPV of 92% for joint subluxation. Fracture displacement of 35% had a specificity of 92% and an NPV of 94% for joint subluxation. Chapter 4: we wanted to report the rate of pathologic fractures among patients with primary bone tumors of the metacarpals and phalanges and to study the potential predictors of the occurrence of pathologic fracture. We found that 49% of the tumors presented as a pathologic fracture. The small finger was independently associated with pathologic fractures. Tumors of the metacarpal bones were the least likely to fracture. Chapter 5: the aim was to report the rate of postoperative subluxation and arthritis. Fourteen percent had postoperative dorsal subluxation after initial surgery. Fifty percent of the joints with postoperative arthritis had postoperative subluxation compared with 21% of joints without postoperative subluxation. No significant association was found between postoperative dorsal subluxation with postoperative arthritis. Chapter 6, we studied the reoperation rate of PIP joint involved fractures. Of the 161 fingers, 16% underwent revision surgery. Open fracture was independently associated with revision surgery. The most common indication for reoperation was joint stiffness (35%). Chapter 7: we studied the reoperation rate of all open phalangeal fractures. Furthermore, we studied the factors associated with postoperative nonunion and infection. Overall, 340 of 1321 (26%) injured fingers underwent secondary surgery injured fingers underwent secondary surgery. Fractures involving the thumb had lower odds of undergoing secondary surgery. Crush injury, proximal phalangeal fracture, arterial injury, other injured fingers, and other injuries to the ipsilateral hand were associated with higher odds of undergoing secondary surgery. Other injury to the ipsilateral hand, vein repair, and external fixator as initial treatment were associated with postoperative nonunion. Crush injury and proximal phalangeal fracture were associated with postoperative infection. Chapter 8: we studied the rate of and factors associated with Depression in patients presenting at the outpatient clinic with a hand condition. We found that 1 in 8 patients had un(der)treated symptoms of depression. Having multiple pain conditions, a history of depression, and greater limitation from pain for daily activities were independently associated with Depression. Chapter 9: we studied the rate of Depression in patients presenting with a fingertip injury. Furthermore, we aimed to determine the threshold QuickDASH score for Depression. Eight of 56 patients had Depression. A threshold value of the QuickDASH of 50 showed a sensitivity of 88% and a specificity of 81%, with a NPV of 95% for Depression.