Quantitative Evaluation of the Thickness of the Available Manipulation Volume Inside the Knee Joint Capsule for Minimally Invasive Robotic Unicondylar Knee Arthroplasty

Abstract

Developing robotic tools that introduce substantial changes in the surgical workflow is challenging because quantitative requirements are missing. Experiments on cadavers can provide valuable information to derive workspace requirements, tool size, and surgical workflow. This work aimed to quantify the volume inside the knee joint available for manipulation of minimally invasive robotic surgical tools. In particular, we aim to develop a novel procedure for minimally invasive unicompartmental knee arthroplasty (UKA) using a robotic laser-cutting tool. Methods: Contrast solution was injected into nine cadaveric knees and computed tomography scans were performed to evaluate the tool manipulation volume inside the knee joints. The volume and distribution of the contrast solution inside the knee joints were analyzed with respect to the femur, tibia, and the anatomical locations that need to be reached by a laser-cutting tool to perform bone resection for a standard UKA implant. Results: Quantitative information was determined about the tool manipulation volume inside these nine knee joints and its distribution around the cutting lines required for a standard implant. Conclusion: Based on the volume distribution, we could suggest a possible workflow for minimally invasive UKA, which provides a large manipulation volume, and deducted that for the proposed workflow, an instrument with a thickness of 5-8 mm should be feasible. Significance: We present quantitative information on the three-dimensional distribution of the maximally available volume inside the knee joint. Such quantitative information lays the basis for developing surgical tools that introduce substantial changes in the surgical workflow.

Miniature parallel robot with submillimeter positioning accuracy for minimally invasive laser osteotomy

“…The dimensions of the manufactured prototype are close to the dimensions of standard tools used for knee arthroscopy, as the main body of the prototype has a height of 7.6 mm. This height is also below 8 mm, which is the upper boundary of the manipulation space's thickness we expect to be available for a large portion of the cutting locations in minimally invasive UKA [20]. However, the prototype's height of 7.6 mm does not include additional space that the mechanism's legs may require.…”

“…However, in other procedures, for example, in knee arthroplasty, large-area bone machining is required to generate bone cuts of several centimeters length or surface milling of several square centimeters [19,20]. Effort has been invested in making knee arthroplasty procedures less invasive.…”

“…Concerning challenge (iii) on small dimensions and a narrow manipulation space, we aim at a device height below 8 mm for our prototype, according to our first target application (UKA). This height limit is based on the manipulation volume that we expected to be available for a minimally invasive intervention inside the knee joint based on cadaver experiments previously performed [20], as well as on 1) guides a robotic endoscope (2) for minimally invasive laser osteotomy, including its actuation unit (3). The laser is guided through the endoscope to the endoscope tip segment ( 4) by an optical fiber (5).…”

Robotic Endoscope System for Future Application in Minimally Invasive Laser Osteotomy: First Concept Evaluation

“…This laser positioning device is designed to require minimal manipulation space above the bone and can be operated in confined spaces such as inside a joint. We have also investigated cadaveric knee joints to quantify the available manipulation space for robotic instruments during a minimally invasive UKA procedure [10]. However, we did not yet show how this laser positioning device and the supplies required for intervention (e.g., the laser fiber) can be inserted into the patient and deployed at the intervention site in a minimally invasive manner.…”

“…This amount of manipulation space is not available during minimally invasive procedures on This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ bones such as in joints (maximally 8 mm based on our evaluation [10]).…”