Hip instability is one of the most common complications after total hip arthroplasty (THA). Among the possible techniques to treat and prevent hip dislocation, the use of constrained liners is a well-established option. However, there is concern regarding the longevity of these devices due to higher mechanical stress caused by limited hip motion. The primary aim of this paper is to analyze the failure rate of a specific constrained liner in a series of consecutive cases. This study is a retrospective consecutive case series of THA and revision hip arthroplasty (RHA), in which a constrained polyethylene insert was used to treat or prevent hip instability. Patients were divided in 3 different groups (THA for hip fracture, THA for osteoarthrosis, and RHA). Survival analysis was performed for failure, defined as at least one episode of hip dislocation or radiographical signs of acetabular loosening. Logistical regression was used to investigate risk factors for failure. A total of 103 patients were included in the study. Fourteen patients (13,6%) were THA for osteoarthrosis, 60 (58,3%) were THA for hip fracture, and 29(28,2%) were RHA. The median follow-up was 28 months (ranging 12 − 173 months). Failure occurred in 4 cases (3,9%) comprehending 2 dislocations (1,9%) and 2 early acetabular loosening (1,9%). Amongst the groups, there were no cases of failures in the THA due to osteoarthrosis, in the THA for hip fracture there were 3 cases (5%) and in the RHA one case (3,4%). Failure-free survival was not statistically different between groups. There were no risk factors statistically related to failure. The use of constrained acetabular insert to prevent or treat instability achieved an adequate survival time with a low rate of complications. Further studies are necessary to corroborate our findings.
Dislocation is one of the most common and disturbing complications after total hip arthroplasty (THA). This is a challenging situation, especially in patients with a high risk of dislocation. Constrict acetabular liner is among the different types of technics for preventing instability. Describe the radiological and clinical results of patients submitted to a primary or revision THA using a constrict acetabular liner. 52 patients with high risk for dislocation were operated between 2006 and 2015 with a constrict acetabular liner. They were evaluated clinically and radiographically after 3 months, 6 months and 1 year after surgery and them annually. The Merle D'Aubigné Postel Method was used to access the clinical outcomes and anteroposterior pelvic and hip profile radiography was performed to access any evidence of loosening of the acetabular cup. 33 (63%) patients were female, the average age were 80 (52 – 94) years old. 29 (75%) cases were primary THA and 13 (25%) revision surgery. The mean follow up was 49(19 – 126) months. 31 (59%) patients died during the study, 5 deaths (9.6%) occurred in the first 3 months after surgery. There were 4 unsatisfactory results: 2 (3.8%) dislocations (secondary to high energy trauma) and 2 (3.8%) early aseptic loosening that required revision surgery. The median preoperative global score of Merle D'Aubigné Postel was 16.7% and the postoperative was 88.9%. The population that presented the least improvement in the clinical outcome (< 50% of improvement) were patients with previous surgery on the same hip (p<0.0001) and revisions surgeries due to instability (p=0.005). When comparing the mortality rate with the percent of clinical improvement after surgery, there was no statistic difference. Constricted acetabular liner is a good option for treatment in selected cases, with a low rate of complications and a good implant survival with a short follow up.
