Can Robotic-Arm Assistance Decrease Iatrogenic Soft-Tissue Damage During Direct Anterior Total Hip Arthroplasty?

Introduction: Manual techniques for total hip arthroplasty (THA) have been widely utilized and proven to be clinically successful. However, the use of advanced computed tomography (CT) scan-based planning and haptically-bounded reamers in robotic-arm assisted total hip arthroplasty (RTHA) holds promise for potentially limiting surrounding soft-tissue damage. This cadaver-based study aimed to compare the extent of soft-tissue damage between a robotic-arm assisted, haptically-guided THA (RTHA) and a manual, fluoroscopic-guided THA (MTHA) direct anterior approach.

Materials and methods: There were six fresh-frozen torso-to-toe cadaver specimens included, with two surgeons each performing three RTHA and three MTHA procedures. One hip underwent an RTHA and the other hip received an MTHA in each cadaver. Postoperatively, one additional surgeon, blinded to the procedures, assessed and graded damage to nine key anatomical structures using a 1 to 4 grading scale: (1) complete soft-tissue preservation to <5% of damage; (2) 6 to 25% of damage; (3) 26 to 75% of damage; and (4) 76 to 100% of damage. Kruskal-Wallis hypothesis tests were used to compare soft-tissue damage between RTHA and MTHA cases and adjusted for ties.

Results: Pooled analysis of the gluteus minimus, sartorius, tensor fascia lata, and vastus lateralis muscle grades demonstrated that cadaver specimens who underwent RTHA underwent less damage to these structures than following MTHA (median, IQR: 1.0, 1.0 to 2.0 vs. 3.0, 2.0 to 3.0; p=0.003). Pooled analysis of the calculated volumetric damage (mm3) for the gluteus minimus, sartorius, tensor fascia lata, and vastus lateralis muscles demonstrated that the cadaver specimens that underwent RTHA underwent less damage to these structures than those that followed MTHA (median, IQR: 23, 2 to 586 vs. 216, 58 to 3,050; p=0.037).

Conclusion: This cadaver-based study suggests that utilizing RTHA may lead to reduced soft-tissue damage compared with MTHA, likely due to enhanced preoperative planning with robotic-arm assisted software, real-time intraoperative feedback, haptically-bounded reamer usage, reduced surgical steps, as well as ease of use with reaming. These findings should be carefully considered when evaluating the utilization of robotic-arm assisted THA in practice.