Archives of Orthopaedic and Trauma Surgery - 2026-05-07 - Journal Article
Robotic-arm assisted total hip arthroplasty using a short metaphyseal filling collared femoral implant through a direct anterior approach: minimum two-year outcomes.
Marchand R, Kaczynski E, Taylor K, Smitterberg C, Mont MA
Topics
Key Takeaway
A short collared metaphyseal-filling stem via robotic-arm assisted DAA THA achieved 98.1% survivorship and HOOS-JR improvement from 54.5 to 94.4 at mean 2.6-year follow-up.
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Summary
This study evaluated functional outcomes, complications, and survivorship of a short collared metaphyseal-filling stem implanted via robotic-arm assisted DAA THA at minimum 2-year follow-up in 120 patients (mean age 69.2, 71% female). HOOS-JR improved from 54.5 ± 13.9 preoperatively to 94.4 ± 10.3 (P < 0.001). Survivorship was 98.1% with two septic revisions and no aseptic mechanical failures reported.
Key Limitation
The absence of a comparator group (conventional stem, non-robotic DAA, or posterior approach) makes it impossible to isolate the contribution of implant design, robotic assistance, or approach to the reported outcomes.
Original Abstract
INTRODUCTION
Short, collared, metaphyseal-filling femoral stems preserve proximal bone and achieve stable fixation while reducing stress shielding compared to diaphyseal-engaging stems. Early six-month data for one such stem demonstrated improved patient-reported outcomes with no implant-related complications. This study extends follow-up of the same cohort to a minimum of two years to evaluate (a) functional outcomes, (b) implant-related complications, and (c) survivorship.
MATERIALS AND METHODS
The prospective cohort of 120 patients underwent robotic-arm assisted total hip arthroplasty (THA) through a direct anterior approach (DAA) using a short, collared, metaphyseal-filling stem. Patients had a mean age of 69.2 years (range 37-90) and a body mass index of 28.2 (range 18.1-49.1), and they were 71% women and were followed for a mean of 2.6 years (range 2.0-3.4). The Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR) was compared with baseline using Student's t-tests. Complications included all-cause revision, periprosthetic joint infection, periprosthetic fracture, and dislocation at final follow-up.
RESULTS
At mean follow-up, HOOS-JR scores improved from a mean of 54.5 ± 13.9 preoperatively to 94.4 ± 10.3 (P < 0.001). The overall survivorship was 98.1% following two septic revisions.
CONCLUSIONS
This short, collared, metaphyseal-filling stem demonstrated sustained functional improvements and low implant-related complication rates of the prior six-month follow-up through a minimum of two years. These results support the continued clinical efficacy and stability of the implant in robotic-arm assisted DAA THA.