Robotics in arthroplasty

Robots and robotic technology are a source of human fascination. Aristotle (322BC) dreamt of robots, and Leonardo da Vinci (1495AD) designed one.¹ Currently, there are numerous commercially available and developmental robotic devices for all types of hip and knee arthroplasty. These devices have varying levels of evidence to support their usage; perhaps the most pertinent question is, have robots reached the stage where they are relevant to orthopaedics today?

Responsible introduction of new technology is now considered essential following various implant failures in the recent past. Malchau proposed a now widely accepted stepwise algorithm for this purpose.² This involves:

1. Initial preclinical testing

2. Small randomised trials with sensitive outcome measures (e.g. RSA)

3. Larger clinical studies

Once these stages have been completed, multicentre trials followed by Registry studies should be undertaken.

This review will examine how robotic technology has been introduced to the competitive orthopaedic market, and what the evidence is to support its use.

Background

A robot is a machine capable of carrying out a complex series of actions automatically, especially one programmable by a computer. Robots of many kinds have become commonplace since the first industrial robot was installed in 1961 to unload parts from a die casting operation.

More recently there has been a surge of interest in robotic surgery, led by the da Vinci robot (Intuitive Surgical, Sunnyvale, CA, USA). This allows a surgeon to remotely control laparoscopic instruments with increased precision and dexterity.^3–5 The usage of this robot has increased from around 200 000 procedures per annum in 2009 to over 550 000 procedures worldwide in 2014.⁶ This still represents only a very small percentage of the total number of similar procedures performed using traditional methods, but the growth in the usage of this technology is forecast to continue at a rapid rate.

The use of robotics in joint arthroplasty has developed immensely over the past 30 years and differs in concept from the da Vinci robotic surgery. The relative rigidity of bone allows pre-operative imaging and pre-planning of bony cuts, essentially enabling the robot to perform large sections of the surgery in an automated manner. Intra-operative adjustment of the plan according to the patient’s soft tissues can generally be made, and it is this precision and accuracy of adherence to the surgeon’s plan by the robotic cutting tools that is the major proposed benefit of robotic-assisted joint arthroplasty surgery.

History

The first robot designed for orthopaedics, and total hip arthroplasty (THA) in particular, was the ROBODOC (Think Surgical, Fremont CA., USA) system. This was a collaboration between the IBM Watson Center and UC Davis in 1986. The system underwent dry bone and cadaveric validation over the next six years, until the first patient had a THA with the femoral canal milled by an autonomous robot in 1992.⁷ During this time, the team at University of Washington had demonstrated the concept of cutting a distal femur for total knee arthroplasty (TKA), utilising an industrial robot on bone models in a theatre environment.⁸ ROBODOC was later modified for use in TKA.⁹ The CASPAR (OrthoMaquet, Rastatt, Germany) system followed hot on ROBODOC’s heels in 1999¹⁰, and this was also designed for femoral preparation in THA. This system was then developed again to be used for bony cuts of TKA.¹¹

In 2001, the first paper was published describing surgery with robotic assistance in unicompartmental knee arthroplasty (UKA) utilising the Acrobot (Imperial College, London, UK).¹² A simple system consisting of a robotic surgical arm with a burr as the end effector, it required the rigid fixation of limb to a frame, a significant drawback in the operating theatre.