Abstract Background Total hip arthroplasty (THA) altered the mechanical axis and loading distribution of the lower extremity. The effect of a prior THA on clinical outcomes of a subsequent ipsilateral total knee arthroplasty (TKA) remains unknown. Methods We reviewed 83 patients who underwent ipsilateral THA and TKA for rheumatoid arthritis or osteoarthritis between January 2008 and April 2014. Forty-seven patients were classified as TKA followed by ipsilateral THA (THA-TKA group) and 36 as THA subsequent to ipsilateral TKA (TKA-THA group). Twenty-eight patients (30 hips and knees) were selected for each group after the propensity score was matched with preoperative demographics and hip-knee-ankle angle (HKA). Clinical measurements, radiographic evaluations, and complication data were compared between 2 groups. Results Both groups had a significant improvement in modified Harris Hip Scores (HHS), Knee Society Score (KSS), and Short Form-12 at final follow-up compared to baseline ( p &lt; .001). The clinical parameters were actually lower in THA-TKA group. However, those differences were not significant ( p &gt; .05). Meanwhile, there was no significant difference in postoperative radiographic axial alignment and implant survivorship (90.0% vs 96.7%, p = .305). The rate of complication was also similar in both groups. Conclusions A prior THA does not appear to influence clinical outcome of a subsequent ipsilateral TKA. Patients with different sequence of ipsilateral THA and TKA have similar mid-long term clinical outcomes and implant survivorship. Trial registration: The trial was registered in the Chinese Clinical Trial Registry (ChiCTR2000035147) dated 2rd August 2020.

Mid-long term results of total knee arthroplasty followed by ipsilateral total hip arthroplasty versus total hip arthroplasty subsequent to ipsilateral total knee arthroplasty: A retrospective cohort study