Postgrad. med. J. (November 1968) 44, 848-850.

Hard and soft osteo-arthritis

C. P. BROADM. B., F.R.C.S.

The Rowley Bristow Orthopaedic Hospital, Pyrford, Surrey

SummaryThis short paper attempts to show how the

X-ray appearance influences the choice andsuccess of operative procedures performed on thehip and knee joints for osteo-arthritis. If thebones look 'soft' the only methods likely to suc-ceed are those in which total replacementcoupled with the use of cement ensure firmanchorage and wide distribution of stress. Whenbones look 'hard' simpler methods are usuallysatisfactory.

IN THE treatment of osteo-arthritis it is usuallyeasy to decide whether or not operative treatmentis indicated: but frequently it is difficult tochoose which operation is best suited to theindividual patient. The three basic procedures arearthrodesis, osteotomy and arthroplasty. Arthro-desis is usually reserved for those patients inwhom one joint only is involved, the 'compensat-ing' joints are reasonably supple and the patientfairly young. Osteotomy is most likely to succeedwhere the joint has a reasonable range of move-ment and the disease is not so advanced thatbone collapse precludes the probability of jointregeneration. Arthroplasty is the only feasibleprocedure for all other patients and nowadays avariety of techniques is available.The present hypothesis is not concerned with

those cases selected for arthrodesis. It attemptsto rationalize the choice between osteotomy andarthroplasty as well as indicating which techniqueof arthroplasty should be used.The hip and knee joints were selected for study,

these being the joints at which the problem wasmost often encountered. When patients were ex-amined at least 2 years after operation it wasrelatively easy to decide which were successfulor which were failures. Next the X-ray filmswere studied and again two clear-cut groupsemerged; those in whom the bones looked 'hard'(Fig. la) and those in whom they looked 'soft'(Fig. lb). The third stage of the investigation wasto try and correlate success or failure with hard-ness and softness of bone. The thesis of this articleis that such a correlation not only exists but is

remarkably constant and has a rational basis inpathology.Secondary osteo-arthritis may follow mechan-

ical anomalies (e.g. fractures into the joint, devel-opmental disorders, mal-alignment, etc.) in whichcase the texture of the bone is relatively normaland it looks 'hard' on X-ray. But when the degen-erative changes are secondary to rheumatoidarthritis the bone looks 'soft', as it also does inosteoporotic disorders.When 'soft' bone osteoarthritis of the hip was

treated by prosthetic replacement of the femoralhead the result was often unsatisfactory. Pain wasnot relieved or it subsequently recurred; and laterX-ray films showed the prosthesis migrating downthe femoral shaft, or burrowing into the pelvis, orboth (Fig. 2). Even osteotomy rarely succeeded,presumably because any biological regenerationwas more than offset by the continuing collapseof the soft bone. But even with 'soft' bone atotal hip-replacement using McKee's techniquewas nearly always successful. The essentialfeature is probably the wide distribution of stressafforded by the use of the cement which anchorsthe metal components.With 'hard' bone osteo-arthritis at the hip,

procedures less elaborate than total replacementwere usually adequate. Osteotomy was successful(providing the joint preoperatively had at least700 of flexion and little bone collapse hadoccurred), and cup arthroplasty or simple re-placement of the femoral head with a Moore'sor Thomson's prosthesis were also satisfactory.Similarly Ring's total hip replacement althoughnot employing cement was successful, presum-ably because the long screw carrying the acetabu-lar component obtained an excellent grip on the'hard' bone of the ilium.At the knee the findings were similar. With

'soft' bone osteo-arthritis neither osteotomy norsimple tibial plateau replacement proved reliable;continuing collapse caused failure and successcould be obtained only by using total knee re-placement in which each component wasanchored with cement distributing the loadwidely. When the bone was 'hard' osteotomy or

Protected by copyright.

on 7 March 2019 by guest.

http://pmj.bm

j.com/

Postgrad M

ed J: first published as 10.1136/pgmj.44.517.848 on 1 N

ovember 1968. D

ownloaded from

Hard and soft osteo-arthritis 849

FIG. 1. 'Hard' (a) and 'soft' (b) osteo-arthritis.

FIG. 2. (a) A Moore's prosthesis which has been inserted in the presence of 'soft' bone. (b) The same hip asillustrated in (a) after an interval of 3 years. The prosthesis has sunk down the shaft of the femur and into theacetabulum.

*....

-:.....5:..

Protected by copyright.

on 7 March 2019 by guest.

http://pmj.bm

j.com/

Postgrad M

ed J: first published as 10.1136/pgmj.44.517.848 on 1 N

ovember 1968. D

ownloaded from

850 C. P. Broad

tibial plateau prosthetic replacement were usuallysatisfactory.

ConclusionsIn choosing between the various procedures

available in the surgical treatment of osteo-arth-ritis the radiographic appearance of the bones isof considerable importance. If the bones look'soft' the only methods likely to succeed are those

in which total replacement coupled with the useof cement ensure firm anchorage and wide dis-tribution of stress. When the bones look 'hard'simpler methods are usually satisfactory.

AcknowledgmentI wish to thank Mr A. Graham Apley who encouraged

me to develop this thesis.

Protected by copyright.

on 7 March 2019 by guest.

http://pmj.bm

j.com/

Postgrad M

ed J: first published as 10.1136/pgmj.44.517.848 on 1 N

ovember 1968. D

ownloaded from