[Characteristics and clinical significance of irreducible Pipkin type

Objective: To summarize the characteristics and clinical significance of irreducible Pipkin type Ⅰ and Ⅱ femoral head fracture-dislocations. Methods: The clinical data of 4 patients with irreducible Pipkin type Ⅰ and Ⅱ femoral head fracture-dislocations between January 2010 and December 2019 were collected. There were 2 males and 2 females and the age ranged from 24 to 41 years, with an average age of 33.5 years. The cause of injury included traffic accident in 3 cases and falling in 1 case. Pipkin classification was 2 cases of type Ⅰ and 2 cases of type Ⅱ. The time from injury to operation was 1-2 days. The clinical features were that the hip joint of the affected limb was in a locked position, and the passive range of motion was poor. The affected limb was slightly flexed at the hip joint and shortened, in a state of neutral position or slight adduction and internal rotation. The imaging data suggested that the femoral head dislocated backward and upward, and the hard cortex of the posterior edge of the acetabulum was embedded in the cancellous bone of the femoral head, and the two were compressed and incarcerated. Patients of cases 1-3 underwent closed reduction of hip dislocation 1-2 times at 3, 1, and 3 hours after injury respectively, and femoral neck fracture occurred. The injury types changed to Pipkin type Ⅲ, and open reduction and internal fixation were performed. Patient of case 4 did not undergo closed reduction, but underwent open reduction and internal fixation directly. Results: Patients of cases 1-3 were followed up 14, 17, and 12 months, respectively. They developed osteonecrosis of the femoral head at 9, 5, and 10 months after operation respectively, and all underwent total hip arthroplasty. Patient of case 4 was followed up 24 months and had no hip pain and limited mobility; the imaging data indicated that the internal fixator position was good and the fracture healed; no collapse or deformation of the femoral head was seen, and no osteonecrosis of the femoral head occurred. Conclusion: Clinicians need to improve their understanding of the unique clinical features and imaging findings of irreducible Pipkin type Ⅰ and Ⅱ femoral head fracture-dislocations. It is suggested that open reduction and simultaneous fixation of femoral head fracture should be directly used to reduce the incidence of osteonecrosis of the femoral head.