Plenary Lectures / Journal of Biomechanics 43S1 (2010) S3–S14 S13

this class of mechanisms takes the advantage of characteristics

of mobility change of metamorphic mechanisms to change the

structure of a palm during operation, leading to supplementary

mobility, easy grasping and more dexterity of the multi-fingered

hand, forming a novel prosthetic hand.

The plenary speech presents the inherent properties of

metamorphic mechanisms and the extensive application of the

new kind of mechanisms in the development of surgical and

rehabilitation devices. Since the first surgical robot was initiated

in 1985, surgical robotics has progressed for approximately

25 years in conjunction with mechanism development. In the

next 25 years, mechanisms development promises huge progress in

surgical robotics comparable to the development of manufacturing

robotics in industrial production over the past 25 years. The

trend has been clearly indicated by the latest technology that

provides superior visuals and enhances dexterity for the surgeon

and by the worldwide market value expected to be $5.7

billion by 2011 for medical robots and computer-aided surgery

devices and equipment. The multidisciplinary work and the

conjunction between mechanisms development and medical device

development promise the rapid progress of both surgical and

rehabilitation robotics.

P-22

The Role of Computer Navigation in Assessing Knee Kinematics

During Total Knee Replacement

A. Adhikari. The South West London Elective Orthopaedic Centre, UK

Total Knee Replacement (TKR) has been recently referred to as

the ‘joint of the decade’. TKR has proved to be an extremely

successful operation that has provided a much improved quality

of life for millions of patients suffering from arthritis of their knees.

Many designs of total knee replacement that are being implanted

currently have a survivorship of more than 90% for 10 years.

Good outcome following total knee arthroplasty is collectively

dependent on many factors. Accurate alignment of the prosthetic

components is most stressed upon. The effects of appropriate

soft tissue balancing are very closely intertwined. Needless to

mention is the importance of other operative steps including aseptic

precautions in the operation theatre.

Acceptable range for coronal plane alignment of the knee prosthesis

has been defined as +/− three degrees with respect to mechanical

axis of the lower limb. The TKR not within this alignment range

have worse long-term outcomes. In recent years, use of Computer

Navigation has resulted in improved accuracy of knee prosthetic

placement and limb alignment.

Modern designs of TKR rely on congruence of the metal

and polyethylene components for stability. However, the

reestablishment of proper knee kinematics through both medial-

lateral and flexion-extension ligamentous balancing is a factor well

within the surgeon’s decisive control. Respectful management of

the extensor mechanism has also been stressed up. Assessment of

soft tissue balance has however remained largely subjective.

The advent of Computer Navigation and improved instrumentation

has allowed precise determination of various intra-operative

parameters. This has the added advantage in that every operative

step and measurement is recorded. It is also now possible to assess

passive kinematics of the knee intra-operatively. Improvements

in hardware have been followed side by side with software

development enabling us to use different techniques of knee

replacement with computer navigation assistance using the same

prosthesis.

P-23

Shoulder Surgery – A Perspective of 40 Years

S. Copeland. Reading Shoulder Unit, Royal Berkshire Hospital, UK

Speed of change in surgery appears to be exponential. I am sure

each generation of surgeons feel that they have seen the greatest

change of all generations. I am convinced we have seen the greatest

change – so far.

Surgeon training has changed from the apprenticeship system to

‘fly by wire’ training on simulators. We have progressed in the

type of surgery we do from open major invasive surgery to keyhole

minimally invasive surgery. Progression from the mechanical to the

electronic age has enabled miniaturisation. The speed of computer

development has allowedmassive data manipulation as an everyday

occurrence. The body can now be investigated so much more

accurately that surgery concentrates on correcting what is wrong

rather than the morbidity associated with the approach. This has

certainly lead to better results but maybe at the expense of certain

clinical skills – we may have gone too far and need to address this

in training.

Navigation and robotics are replacing the need for extended

cognitive surgical training. We are moving from tissue manipulation

to cell manipulation and really focussing down on the ‘why’ more

than the ‘how’.

The development of joint replacement now a totally accepted

technique, is all entirely within one surgical generation. What I do

now bears no relationship to the job I was trained to do 40 years

ago. If the speed of change really is exponential, I really regret not

being around for the next 40 years, they are exciting times.

P-24

Shoulder Arthroplasty, Past and Present – and Where are We

Going?

O. Levy. Reading Shoulder Unit, Royal Berkshire Hospital, UK

The first joint replacement in the human history was performed

on the shoulder by Themistocles Gluck in 1890 that used an ivory

prosthesis for Tuberculosis. He experimented with cadaveric bone

and ivory and with fixation in the bone using copper amalgam,

plaster of Paris and stone putty. Unfortunately, he has not recorded

any results of these shoulder arthroplasty and he has stopped

here arthroplasty work a year later. The first documented joint

replacement was a total shoulder replacement performed by Emile

Pean in 1893 after an excision of the shoulder joint for tuberculosis.

This prosthesis has lasted only two years due to the recurrence of

infection.

Modern shoulder replacement started in the UK in 1950 by Jackson-

Burrows at the Royal National Orthopaedic Hospital in Stanmore for

the treatment of tumours after massive resection of the proximal

humerus. These were salvage operations as the prosthesis was used

as a spacer. The resection of the soft tissue envelope due to the

tumour in these cases, resulted in poor function.

The Stanmore shoulder was developed in 1969. This was a modified

hip prosthesis which was constrained. These implants failed due to

increased torque on the cemented lateralised glenoid fixation. Its

usewas abandoned due to high complication rate with dislocations

and loosening. Other constrained joints were developed at the

era, some of them double jointed and some reversed geometry

prostheses (the Beddow Liverpool shoulder, the Kolbel and the

Kessel shoulders). All these early reverse shoulders have failed

due to the increased lateralisation of the centre of rotation and

increased torque on the glenoid fixation, with loosening of the

glenoid component.

On the other side of the Atlantic in 1951 Charles Neer has designed

his shoulder replacement initially to treat the four part factures.

Only later on, after this was successful, a glenoid component was

designed for the use in the cases of arthritis, and unconstrained

total shoulder replacement was introduced.

The development of shoulder replacement was initiated therefore,

mainly to treat infection by Gluck and Pean for tumours by the

Stanmore constraint prosthesis and for fractures by Neer. None of

these early developments were specifically designed for arthritis.

The first stemmed prostheses were made mono-block which

necessitated large number of different sizes in length and head.