geometry lead to continuous changes in contact geometry

seen from wear pictures. Examples of distortions following

overload produced by mechanical factors are seen occuring

early on, before the bone adjusts to the new situation. It

is not just failure in the implant, this is too narrow a view,

but the whole system must be analysed. Hence, retrieval is

a step in the analysis of the whole performance of implants

and is very valuable for improvement of implant design.

The underlying concept for this meeting was presented

at the outset when it was pointed out that although

laboratory measuring methods can produce standardized data,

which are of value to the manufacturer of implant materials

and devices, the examination of retrieved implants gives the

ability to learn of the durability and performance of these

under actual service conditions. There is no other way by

which this information can be gained than by examination

of the consequences of human in vivo application, and this

message was constantly reiterated throughout the course of

the conference.

G .W. Hastings

British Orthopaedic Association Spring Meeting Canterbury, UK, 1 O-l 2 April 1980

Over 300 delegates were assembled for the biannual meeting,

held on this occasion at the University of Kent. Owing to

the size of the audience, all presentations were transmitted

live by audio-visual aids to an overspill lecture theatre

showing identical slides. Microphones and public address

systems were installed in each theatre allowing free

disussion between both audiences and the speakers.

The meeting was opened by the Pro-Vice Chancellor

of the University, Professor Maurice Vile, who welcomed

delegates from all countries and wished every success for

the following three days.

A wide range of papers were presented throughout

the meeting and the standard of presentation was high

throughout. A selection of films were shown each morning

simultaneously with the lectures which necessitated the

sacrifice of one of these activities in favour of the higher

priority. Sadly further sacrifices were involved in the

interests of refreshment which was provided continuously

rather than in formal breaks.

Summary of the first day The morning opened with two papers on low modulus

materials for internal fixation devices; namely carbon fibre

reinforced epoxies and titanium alloy. Whilst both papers

concerned the use of less rigid fixation, the objectives of

each were significantly different. The former material,

described by Mr. K.J. Tayton (Cardiff) was employed to

give stable reduction of the fracture throughout the early

healing period by periosteal callus, whilst the latter,

described by Professor H.K. Uhthoff (Ottawa) was used to

stimulate a minimal amount of callus, merely as an indicator

of the progression of ‘primary bone healing’ (cortical

remodelling). Both types of plate were expected to alleviate

the late effects of plate induced osteopoenia.

The use of a unilaterally applied external fixator for

the treatment of tibia1 diaphyseal fractures was described

by Mr. J. Kenwright (Oxford). Early use of such a system

was recommended and delayed union necessitating early

supplementary bone grafting was cited as the main

disadvantage.

The indications and complications of open or closed

intramedullary nailing of the tibia were then presented by

Mr. I.W.L. Bintcliffe (London). In 36 cases of which

172 Biomaterials 1980, Vol 1 July

approximately one third were opened at operation, all

cases united giving good functional results. Infection was

the main complication which was exacerbated by open

reduction.

A novel method of reconstruction of compound skin

and bone defects of the tibia was presented by Mr. R.

Sanders (London). This technique involves free flap transfer

of iliac crest and skin on the deep circumflex iliac artery.

The value of lateral stress radiographs in the demon-

stration of anterior instability of the ankle joint was

described by Mr. M. Glasgow (London). This paper was

complemented by Mr. I.M. Sarsam’s presentation concerning

the role of the anterior tibio fibular ligament in talar

rotation and in ankle fractures.

The final scientific paper of the morning concerned

the orthopaedic complications of renal transplantation and

was given by Mr. J.E. Nixon (London). Thirty out of one

hundred and eighty one transplant patients developed

orthopaedic complications over the six year study period.

The commonest and most serious problem was avascular

necrosis of bone. The treatment and pathology of these

patients were discussed.

To close the first morning’s activities, the Presidential

Address was given by Mr. D.L. Evans who has taken over the

post from Mr. W.J.W. Sharrard. Mr. Evans paid tribute to

the late Reginald Watson-Jones and reminded the audience

of his contribution both to orthopaedic surgery and to the

B.O.A. Mr. Evans closed his address with a recording of the

late Sir Reginald Watson-Jones, the effect of which can be

measured by the silence in which it was received.

The afternoon of the 10th took the form of informal

instructional/discussion groups on the subjects of back

pain and sciatica, rigidity in internal fixation, Tharies hip

surface replacement and surgical approaches to the hip

joint.

The instructional group on the significance of internal

fixation of fractures was led by Professor B. McKibbin

(Cardiff) who gave an informative address on the biology

of fracture healing and the influence of the rigidity of

fixation on the processes involved therein. Whilst the

exact mechanisms of periosteal and medullary callus

formation are not known, a greater understanding of the

functional relationship between these healing processes

and so called ‘primary bone healing’ appears to be developing.

J.S. Bradley