# Cup accuracy and early-term clinical outcomes of a novel, pinless, robotic-assisted total hip arthroplasty system: A first-in-human pilot study

## TL;DR

A new robotic system for hip replacement surgery shows accurate cup placement and good patient outcomes in a first-in-human trial.

## Contribution

A pinless, fluoroscopic-guided robotic system for total hip arthroplasty is introduced and evaluated in a first-in-human pilot study.

## Key findings

- The robotic system achieved high accuracy in acetabular cup placement, with most differences within 5° of targets.
- Patients showed significant improvement in hip function and pain reduction one year post-surgery.
- 88.2% of patients reported being very satisfied or satisfied with the procedure after one year.

## Abstract

Malpositioning of the acetabular cup represents a challenge during total hip arthroplasty (THA). The purpose of this study was to evaluate the accuracy of acetabular cup placement and early postoperative clinical outcomes with a novel, pinless, fluoroscopic-guided, robotic-assisted application for direct anterior (DA) approach THA.

This prospective, pre-market phase 2 study enrolled 19 patients undergoing THA for osteoarthritis. Standing anteriorposterior (AP) and lateral radiographs up to 1 year postoperatively were assessed for component fixation and complications. Martell Hip Analysis software was used to assess radiographic acetabular anteversion and inclination from postoperative standing AP pelvis images and the results were compared to target and final component values from the surgical logs. Patient reported outcome measures (PROMs) were collected preoperatively, four weeks, three months, and one year after operation.

Mean absolute difference for anteversion and inclination from respective targets on intraoperative fluoroscopic views was 1.4° ± 1.3° (P = 0.159) and 1.3° ± 1.1° (P = 0.378). The absolute difference between postoperative radiographs and intraoperative target values was 2.91 ± 2.40° (P = 0.019) for anteversion and 3.84 ± 2.57° (P = 0.007) for inclination. The difference in target and postoperative radiographic inclination and anteversion was within 5° in 77.8% of cases, and the cup was within the Lewinnek safe zone in 16 of 18. Oxford Hip Score (OHS) (44.3 ± 4.6 vs. 22.2 ± 11.3), score on Numeric Pain Rating Scale (NRPS) (0.5 ± 1.0 vs. 5.7 ± 2.6), and Hip Osteoarthritis Outcome Score-12 (HOOS-12) Overall Score (91.4 ± 11.2 vs. 42.8 ± 20.1) were significantly improved at one year. At one-year, 88.2% and 11.8% of patients were very satisfied or satisfied.

This first-in-human study on THA utilizing a pinless, fluoroscopy-based robotic arm demonstrated high accuracy in terms of radiographic inclination and anteversion, excellent hip-specific functional outcomes and safety one year after operation.

Video Abstract

Video Abstract

The online version contains supplementary material available at 10.1186/s42836-025-00299-x.