It is safe to use minimal restrictions following posterior approach total hip arthroplasty: results from a large cohort study.

Background: To prevent early postoperative dislocation following a total hip arthroplasty (THA) procedure, patients must adhere to restrictions. Restrictive protocols are common if THA surgery is performed using the posterior approach, but scientific evidence form larger studies that supports these restrictions are scarce. In this large cohort study we compare the Methods: Prospective cohort (n = 1049) of consecutive elective primary hip replacement surgery procedures (September 2014-July 2017) managed with minimal postoperative restrictions. Hospital charts were prospectively reviewed for patient demographics, risk factors and any hip dislocation. Control (n = 1102) consecutive primary elective THAs (January 2011-August 2014) managed with a traditional restrictive protocol. A posterior surgical approach was used in all procedures. Results: Minimal restrictions group: 17 dislocations <90 days (1.6%); Restricted group: 28 (2.5%), chi-square p = 0.1. Testing the hypothesis of inferiority by a minimum of 1% increase in <= 90 days dislocation risk: p = 0.14 (test for difference) and p < 0.001 (non-inferiority test), allowing us to discard the null hypothesis (absolute increase in risk of > 1% with minimal restrictions). The proportion of surgeries performed with a femoral head size > 32 mm was higher in the minimal restrictions group. Conclusions: Patients can be managed safely with minimal restrictions following posterior approach THA if combined with frequent use of larger femoral heads.