Abstract Background: The constrained acetabular cups are widely used to treat instability after hip arthroplasty. Aim of Study: To assess the hip joint function pre and post-operatively after the use of constrained acetabular com-ponent. Patients and Methods: This cross-sectional study included 20 patients who underwent hip arthroplasty. These cases had hip instability either preoperatively or intra-operatively and they were all treated with hip arthroplasty involving the use of constrained acetabular component (The Single Articulation or Double Articulation Constrained cup). The follow-up period ranged from 12 to 30 months (the average was 20.4 months). Results: When compared to the initial (preoperative) Harris hip score, a significant rise of the Harris hip score was measured at 3 months and 1 year postoperatively, [mean 25 vs. 77 vs. 91, respectively]. The improvement between 3 months and 1 year was slight and statistically significant. In the current study, 15 cases (75%) passed uncomplicated; while 5 cases had complications; two cases were dislocated, another two cases developed post-operative infection, one of them was combined with trochanter nonunion, and another case suffered from trochanter nonunion. Conclusion: We concluded that the use of constrained acetabular component is an effective option in the treatment of patients with instability of the hip.