Risk Factors and Preventive Strategies for Dislocation Following Primary Total Hip Arthroplasty: A Large Single-Surgeon Cohort Study

Objective: This study aimed to analyze the incidence and multifactorial causes of dislocation following primary total hip arthroplasty (THA) and to evaluate current surgical strategies for the prevention and management of this complication. Methods: This retrospective study included 1066 hips (median age 57 years; 805 females and 261 males) that underwent primary THA performed by a single surgeon between 1996 and 2025. The median follow-up duration of the patients was 46 months (min: 6, max: 357 months), and 68.9% had primary coxarthrosis, while 31.1% had secondary coxarthrosis. In this study, the effects of dislocation causes, age, gender, femoral head size, liner angle, posterior capsular repair, type of anesthesia, fixation method of the prosthesis, etiology, and surgical experience (distribution by years) on dislocation were statistically analyzed. Results: The analysis revealed that 44 of the 1066 hips (4.1%) developed a dislocation. The most common causes of dislocation were identified as femoral offset error (40.91%) and acetabular component malposition (31.82%). A statistically significant correlation was found between dislocation development and gender (p < 0.001) and femoral head diameter (p = 0.006); the dislocation rate was higher in male patients (8.0%) than in female patients (2.9%). A marked reduction in dislocation rates (1.6%) was observed following the routine use of large-diameter femoral heads (32–36 mm). The highest dislocation rate was observed during the early years of surgical experience (1996–2000, 6.8%). No statistically significant differences were found between dislocation development and age (p = 0.055), type of anesthesia, type of prosthesis, liner angle, and secondary etiological factors (p > 0.05). Conclusions: Instability developing after primary THA is a multifactorial complication. In our study, inadequate femoral offset restoration and acetabular component malposition were identified as the most common mechanical causes of dislocation. Male gender was significantly associated with an increased risk of dislocation, whereas the use of larger femoral head diameters was associated with lower dislocation rates. Our findings suggest that meticulous preoperative planning, accurate component positioning, increased surgical expertise, and the use of larger femoral head diameters may play important roles in reducing the risk of instability.