Navigation & Robotics

 

Cup inclinationCup anteversion

 

Goals

 

Acetabular position

 

Affects dislocation / liner wear / impingement / ROM

 

Lewinnek safe zone

- inclination 40+/-10 degrees

- anteversion 15+/-10 degrees

 

Minimize leg length discrepancy

 

Causes gait disturbance and lower back pain

 

Restore offset

 

Measuring acetabular position

 

Cup inclination

 

Cup inclination

 

Cup anteversion

 

Methods for measuring cup anteversion on xray PDF

 

Cup anteversionCup anteversion

 

Anteversion 1Anteversion 2

 

CT cup anteversion

 

Options for component positioning

 

Mechanical navigation / intra-operative landmarks

Intra-operative fluoroscopy

Image-less optical navigation

CT based navigation

 

Results

 

Fluoroscopy versus no imaging

 

Lecoultre et al Arthroplasty 2023

- systematic review of 10 papers and 1400 papers

- fluoroscopy did not improve cup position / offset or LLD

 

Fluoroscopy versus image-less navigation

 

Manzo et al JAAOS 2024

- fluoroscopy versus image-less navigation in 640 anterior hips

- navigation improved cup anteversion and LLD

 

CT versus fluoro versus no navigation

 

Matsuki et al J Orthop Sci 2023

- 171 hips with post op CT

- CT navigation most accurate in cup placement versus fluoro or mechanical guides

 

CT versus image-less navigation

 

Hasegawa et al Computer Assist Surg 2021

- cup anteversion and inclination more accurate with CT

- accuracy equal if both ASIS included in image-less navigation

 

Conventional alignment guides

 

Mech alignmentmech alignment

Stryker Trident Acetabulum guide

 

Intra-operative fluoroscopy

 

THA fluoroTHA fluroTHA fluoro

 

Advantage

- assesses femoral fit and fill

 

Issues

- 2 dimensional image

- easier in supine position / direct anterior THA

- parallax and distortion

- less accurate for acetabular anteversion

 

Image-less optical navigation

 

Navigation 2Navigation

Smith&Nephew RI Hip Navigation

 

StrykerStryker

Stryker OrthoMap

 

Method

- insert trackers

- register anatomy

- produce an intra-operative 3D image

 

Advantage

- easy to use supine or lateral position

 

Issues

- dependent on registration of bony landmarks

- affected by patient body habitus

- longer surgical times

 

Accuracy

 

Naito et al BMC Musculoskeletal Disord 2021

- 107 navigated THA with postoperative CT

- inclination within 3 +/-3 degrees

- anteversion within 6 +/-5 degrees

 

CT based navigation

 

Makoo 2Mako 1

 

Stryker Mako Hip System

 

Advantage

- can identify bony osteophytes that can cause bony impingement

- highly accurate

 

Issues

- radiation from CT

- longer surgical times

 

Accuracy

 

Hasegawa et al J Orthop Surg Res 2023

- 65 THA with computer navigation and post op CT

- inclination within 2.5+/-2 degrees

- anteversion within 2.5+/-2 degrees

 

Robotics

 

Mako 3Styker MakoMako

Stryker Mako Hip System - CT based

 

Zimmer Rosa Zimmer Rosa

Zimmer Rosa Hip System - intra-operative fluoroscopy based

 

Advantage

- robot reams acetabulum

- can minimize medial reaming

 

Fontalis et al, BJJ 2024

- RCT robot vs conventional THR

- robot had improved accuracy (COR, offset, length, cup)