Improved Patient Reported Outcomes with Functional Articulating Spacers in Two-stage Revision of the Infected Hip

Background: Two-stage revision arthroplasty with an antibiotic-loaded spacer is the treatment of choice in chronically infected total hip arthroplasties. Interval spacers can be functional articulating or prefabricated. Functional results of these spacers have scarcely been reported.

Aim: To compare retrospectively the patient reported outcome and infection eradication rate after two-stage revision arthroplasty of the hip with the use of a functional articulating or prefabricated spacer.

Methods: All patients with two-stage revision of a hip prosthesis at our hospital between 2003 and 2016 were included in this retrospective cohort study. Patients were divided into two groups; patients treated with a functional articulating spacer or with a prefabricated spacer. Patients completed the Hip Osteoarthritis Outcome Score and the EQ-5D-3L (EQ-5D) and the EQ-5D quality of life thermometer (EQ-VAS) scores. Primary outcomes were patient reported outcome and infection eradication after two-stage revision. The results of both groups were compared to the patient acceptable symptom state for primary arthroplasty of the hip. Secondary outcomes were complications during spacer treatment and at final follow-up. Descriptive statistics, mean and range are used to represent the demographics of the patients. For numerical variables, students' -tests were used to assess the level of significance for differences between the groups, with 95% confidence intervals; for binary outcome, we used Fisher's exact test.

Results: We consecutively treated 55 patients with a prefabricated spacer and 15 patients with a functional articulating spacer of the hip. The infection eradication rates for functional articulating and prefabricated spacers were 93% and 78%, respectively ( > 0.05). With respect to the functional outcome, the Hip Osteoarthritis Outcome Score (HOOS) and its subscores (all < 0.01), the EQ-5D ( < 0.01) and the EQ-VAS scores ( < 0.05) were all significantly better for patients successfully treated with a functional articulating spacer. More patients in the functional articulating spacer group reached the patient acceptable symptom state for the HOOS pain, HOOS quality of life and EQ-VAS. The number of patients with a spacer dislocation was not significantly different for the functional articulating or prefabricated spacer group ( > 0.05). However, the number of dislocations per patient experiencing a dislocation was significantly higher for patients with a prefabricated spacer ( < 0.01).

Conclusion: Functional articulating spacers lead to improved patient reported functional outcome and less perioperative complications after two-stage revision arthroplasty of an infected total hip prosthesis, while maintaining a similar infection eradication rate compared to prefabricated spacers.