Late-Onset Femoroacetabular Impingement Syndrome Following Knee Arthroscopy in a Retrospective Cohort

Background/Objectives: Hip-knee coupling is a well-documented phenomenon, and interventions to one joint can alter biomechanics at the other. The purpose of this study was to investigate if knee surgery is associated with later onset of femoroacetabular impingement syndrome (FAIS). Methods: A retrospective chart review was conducted regarding patients at a single academic institution who underwent hip arthroscopy for FAIS between January 2011-October 2021. Patient charts were queried for past surgical history of knee arthroscopy before hip arthroscopy. Patients who previously underwent hip arthroscopy with no history of knee arthroscopy served as controls. Details about demographics and the onset of hip symptoms were abstracted from patient charts. Statistical analysis was conducted using Mann-Whitney testing and binary logistic regression. Results: Of the 1569 patients identified, 127 had a history of knee arthroscopy and reported no hip symptoms at or prior to the time of surgery. Patients who had undergone prior knee arthroscopy were significantly older at onset of initial hip symptoms (42.15 ± 11.80 years versus 34.62 ± 12.49 years, p < 0.001) and at the time of hip arthroscopy (44.12 ± 11.85 years versus 36.90 ± 12.14 years, p < 0.001) when controlling for age, sex, and BMI. These patients first developed hip symptoms at a mean of 8.57 ± 8.53 years following knee arthroscopy (median 6.10 years) and underwent operative treatment 1.76 ± 1.96 years later. Conclusions: Patients with a history of prior knee arthroscopy are older at the time of hip symptom onset and subsequent hip arthroscopy for the treatment of FAIS.