VOL.. 68 B. No. 3. MAY 986 447

UNICOMPARTMENTAL REPLACEMENT AND HIGH TIBIAL

OSTEOTOMY FOR OSTEOARTHRITIS OF THE KNEE

A COMPARATIVE STUDY AFTER 5--b YEARS’ FOLLOW-UP

N. S. BROUGHTON, J. H. NEWMAN. R. A. J. BAILY

Froni Bristol Rota! Infirmary and Winford Orihopaedic Hospital, Bristol

We have made a restrospective comparison between the results of 49 high tibial osteotomies and 42

unicompartmental replacement arthroplasties performed for the treatment of osteoarthritis of the knee,

assessed S to 10 years after operation. The type of operation depended on the policy of the consultant

responsible for treatment but analysis of the pre-operative findings showed that the two groups were

sufficiently similar for direct comparison between them.

In the replacement group, 32 (76%) were good, 4 were fair, 3 were poor and 3 had been revised. In the

osteotomy group 21 (43%) were good, 11 were fair, 7 were poor and 10 had been revised. It was concluded

that, in this series, the results of unicompartmental replacement were significantly better and that this group

had shown no sign of late deterioration.

There has been considerable recent controversy over the

treatment of unicompartmental osteoarthnitis of the

knee. The ideal operation provides pain relief, mobility

and stability over a long period. Total knee replacement,

unicompartmental replacement and tibial osteotomy can

all achieve these objectives. but it seems logical to pre-

serve normal anticular cartilage and to perform the least

destructive operation possible. There have been several

recent reviews of the results of tibial osteotomy and of

unicompartmental replacement but none allowed direct

comparison between the two procedures.

We present a retrospective review of a series of

osteotomies and unicompartmental knee replacements

performed in Bristol between 5 and 10 years ago for uni-

compartmental arthritis. The pre-operative state of each

group was similar enough to allow a direct comparison

ofthe results.

MATERIAL AND METHODS

The records of all patients treated for osteoarthnitis of

the knee by tibial osteotomy or unicompartmental

replacement in Bristol between 1974 and 1979 were

studied.

N. S. Broughton. FRCS. Senior Registrar in OrthopaedicsAddenbrooke’s Hospital. Hills Road, Cambridge CB2 2QQ, England.

J. H. Newman, FRCS. Consultant Orthopaedic SurgeonBristol Royal Infirmary. Marlborough Street. Bristol BS2 8HW,England.

R. A. J. Baily. FRCS. Honorary Research Fellow, University of Bristol(formerly Consultant Orthopaedic Surgeon) Winford OrthopaedicHospital, near Bristol BSI8 8AQ. England.

Requests for reprints should be sent to Mr N. S. Broughton.

(� 1986 British Editorial Society of Bone and Joint Surgery

0301 620X863092 52.00

A total of 70 osteotomies had been performed; I I

patients had died and 10 could not be traced, leaving 49

osteotomies in 45 patients who were followed up and

assessed. All the operations were performed by resecting

a wedge ofbone above the tibial tubercie in an attempt to

correct the coronal tibiofemoral angle. The fibula was

dealt with by osteotomy. excision of the fIbular head or

by releasing the tibiofihularjoint and allowing the fihula

to slide. No external fixation was used; a plaster cylinder

was applied and generally removed six weeks after the

operation.

In the same five-year period, 52 unicompartmental

replacements for osteoarthritis of the knee were per-

formed. Six patients had died and three could not be

traced. leaving a total of 42 unicompartmental replace-

ments in 34 patients. The prosthesis used was the St

Geong sledge cemented in position (Engelbrecht ci a!.

1976). Any abnormality in the coronal tibiofemoral

angle was deliberately undercorrected so that after

operation most ofthe medial compartment replacements

had a coronal tibiofemoral angle between 5 valgus and

5 varus (Figs I, 2 and 3).

Patients were assessed at 5 to 10 years after the

operation by interview, examination and radiography

when this was possible. An objective assessment of the

success of the operation was obtained by using the Baily

knee score (Table I). This scoring system, adapted from

that used at the Hospital for Special Surgery. New York,

has been used regularly in Bristol for 10 years and has

proved to be effective. A score of 35 to 50 points is good,

30 to 34 is fair, and less than 30 points is poor.

Radiographs were assessed by the Kellgren and

Lawrence (1957) grading system for severity of arthritis,

IFig. I

!�. � �

Fig. 2

THE JOURNAL OF BONE AND JOINT SURGERY

448 N. S. BROUGHTON, J. H. NEWMAN, R. A. J. RAlLY

Standing radiographs of the kneesofa patient who was 68 years old atthe time of operation. Figure 1 -

Before operation. Figure 2 - Sixmonths after bilateral medial com-partment replacement with StGeorg sledge prostheses. Noattempt had been made to correctthe coronal tibiofemoral angle tophysiological valgus. Figure 3Five years after the operations.There has been no deterioration inthe lateral compartments and thereis fl() evidence of loosening. Thisfigure shows part of a long-legweight-hearing radiograph: the twolines run from the centre of thefemoral heads to the centre of the

ankle joints.

Table I. The Bails knee assessment scale. The figures shown are the and the coronal tibiofemonal angles were measured onmaximum for each fi.ature: a completely normal knee scores 50 points long-leg standing films. Because the significance of radio-

- - Total lucent lines around the tibial component is questionable,- we did not review this feature but relied upon symptoms

P(lI1l IS to define loosening.

The average duration of the operation for uni-

compartmental replacement was 94 minutes ( ± I 7.5

.5 minutes); it was 68 minutes ( ± I 5.4 minutes) for osteo-_0 tomy (P<0.05). The average hospital stay for the

patients having unicompartmental replacement was 29

days and for those having osteotomy 27 days.

Most of the unicompartment replacements were

10 performed by the senior author (RAJB) on by the lateMr W. G. J. Hampson or their registrars. The osteoto-

5 mies were performed by other Bristol consultants and

� their registrars. There was little evidence of cross-

- referral, the treatment selected being dependent on the

50 policy of the consultant responsible for each case. We

-- - - believe, therefore, that the two groups are essentially

similar, and this is supported by such pre-operative en-

tenia as could be determined retrospectively.

Table II. Comparison of the pre-operative condition of the unicom- RESULTSpartmental replacement and osteotomy groups The pre-operative parameters for the two groups are

Replacement Osteotornv shown in Table II. Patients having osteotomy were in- - �-- .- general younger than those having unicompartmental

71 years 63 years replacement; however, further analysis of the results of

3 1 : I I 38 : I I osteotomy revealed no difference between patients over

60 years of age at operation and those under 60. The

36 33 average period of follow-up for the unicompartmental

6 16 replacement patients was 5.8 years ( ± I .2 years) and for

10.2 9.9 the osteotomy group 7.8 years (± 1.5 years). Again,

further analysis (Table III) showed no significant3.2 3.3 deterioration in the results in the replacement group with

time; all three replacements performed more than eight

1.9 2.0 years previously had good results at review.

We therefore considered that the two groups were

2.0 2.4 similar enough before operation to validate direct com-

- - panison of the long-term outcome.

2.6 years

3 months 4� years

6(NS)

4.4 years

7months 6years

\i)E.. 68 B. No. 3. MAY 986

UNICOMPARTMENTAL REPLACEMENT AND HIGH TIBIAL OSTEOTOMY FOR OSTEOARTHRITIS OF THE KNEE

SevereModerateMildNone

I�i4?l(!iOfl

Walking distance\Valking aidsStair climbingRising from chairGiving way

.%!O5(’flk’flt

I point for each 12 . maximum 120

II3(’/Ol!?litS

No fixed flexion or lagVarus valgus angle

Total

Gru/e of r(’suItGood. 35 50Fair, 30 34Poor, under 30 pC9i)ts

Average age

Female :male

Pre-operative deformityVarus kneesValgus knees

Average deviation from the normaltihiofemoral angle of 7 valgus

Average Kellgren Lawrence scoreiii affected compartment

Average Kellgren Lawrence scorein unaffected compartment

Average Kellgren Lawrence scorein patellofen�oral Joint

06

1215

553.5

5

Table Ill. Results in both groups. also showing the effect of length of follow-up and the timing of revision operations

449

Results

Good 24

Replacement

5-61.years 7 lOyears All

8 32*

Osteotomv

-- 5-61,years 7-lOyears All

6 IS 21*

Fair 2 2 4 5 6 II

Poor 2

Revised

Average timeof revision

Range

I(NS) 3

I0

* Difference significant (P<0.0I)

NS. difference not significant

Table IV. Pain at review for both groups

13

Replacement Osteotomy

26*

2 2

3 10

None 10*

Mild 8

Moderate 3

Severe

Revised

* Difference highly significant ( P <0.001)

14

Table V. Local and general complications recorded for both groups

Replacement

MUA necessary

Wound problems

Osteotomy

2 MUA necessary 2

I Numhsole I

Wound problems 5

Local

General Urinary retention I Deep venous thrombo-sis 3

Thrombocytopenia I Pulmonary embolus I

Chest infection 3

Cardiac arrestand recovery 1

Diedat l5days 1

MUA. manipulation under anaesthesia

Compartment

I

18

16

15

512

8

THE JOURNAL OF BONE AND JOINT SURGERY

450 N. S. BROUGHTON, J. H. NEWMAN, R. A. J. BAILY

Overall assessment. U n icom pa rtment replacement

showed significantly better results than osteotomy (Table

III). There were good results in 43% of the osteotomy

group. and in 76% ofthe replacement group (P<0.0l).

Revision had been necessary in 20% of the osteotomy

group but in only 7% ofthe replacement group.

Pain, function and movement. The I 0 osteotomy and

three replacement patients who had had a revision opera-

tion were excluded from this analysis. Of the remaining

patients. the replacement group had significantly less

pain. 62% of them being completely pain-free (Table

IV). The replacement group also scored better for func-

tioli and fbr movement.

Complications. There were more early systemic complica-

tions and wound problems in the osteotomy group

(Table V).

Radiological deterioration. Only the 37 knees which had

not been revised, and for which pre-operative and post-

operative radiographs were available, could be studied.

Table VI shows that, after tibial osteotomy, it was

unusual for the originally affected compartment to de-

teriorate hut that the opposite compartment frequently

did so. In the unicompartmental replacement group it

was unusual to see radiographic deterioration of the

patellofemoral joint and the originally unaffected com-

partment was seen to deteriorate in only two of I 7 knees.

Analyses of failures. Ten of the osteotomies had been

revised between seven months and seven years after the

original operation (mean 4.4 years). One knee was

revised to a Sheehan total replacement seven months

after osteotomy because of failure to unite. Five other

Table VI. Radiographic deterioration in both groups. subdivided into the three possible compartments

Replacement Osteotomy

Deterioration No deterioration Deterioration No deterioration

Originally ifiected 2

Contralateral 2

Patellofemoral 8

Table VII. The final result related to the pre-operative deformity ofeach knee, giving the number of knees

in each category. and also the mean postoperative score (Table I) for each deformity in each group

Replacement Osteotomy

Result Varus Valgus Varus Valgus

Good 26 6 14 7

Fair 4 7 4

Poor 3 4 3

Revised 3 8 2

Mean score 39.6 ± 7�3* 46.8 + I .8* 35.8 ± 7.0 (NS) 33.9 + 10.8 (NS)

* I)itiercnce highly signifIcant ( P < 0.00 1

NS, difTerence not significant

UNI(OMPARTMENTAL REPI.A(’EMENT ANI) HIGH TIBIAI. OSTEOTOMY FOR OSTEOARTHRITIS OF THE KNEE 451

VOL.. 68 B. No. 3. MAY 986

osteotomies gave inadequate correction and after further

radiographic and clinical deterioration had total knee

replacement. One patient. who had a wound infection

after the osteotomy. then had a Sheehan knee replace-

ment two years later. At that operation there was no

obvious infection, but two years later still an arthrodesis

was necessary for an infected prosthesis. In one patient

the position at the osteotomy had slipped soon after

operation. and the knee was replaced by a Sheehan pros-

thesis after five years; two years later an above-knee

amputation was needed for sepsis. The other two osteo-

tomy patients had technically adequate operations but

because of continued symptoms one had revision to an

arthrodesis and one to a Sheehan total knee, both with

success. The osteotomy patients with poor results were

either managing at home with walking aids and the sup-

port of relatives, or they had declined on been unfit for

further operation.

Three patients required revision operations after

medial unicompantmental replacements. One had a

Kinematic knee prosthesis after three months because of

gross overcorrection into valgus causing rapid de-

terioration of the lateral compartment. The second had a

revision after three years for deterioration of the lateral

compartment and the third had a revision operation after

four and a halfyeans because ofincreasingly severe patel-

lar pain.

Effect of pre-operative deformity. The results are related

to pre-operative deformity in Table VII. Valgus knees

treated by lateral replacement did significantly better

than varus knees treated by medial replacement. but the

number of valgus knees was small. No similar trend was

seen in the osteotomy group.

DISCUSSION

This five- to ten-year follow-up has shown significantly

better results. in terms ofpain and function, for unicom-

partmental replacement than for high tibial osteotomy in

similar groups of patients with degenerative disease of

the knee.

Good early results have been reported for unicom-

partmental replacement(Marmor 1979; Jones ci a!. 1981;

Scott and Santore 1981; Shurley ci a!. 1982). Our results

for this operation are similar to those of Inglis (1984)

who reported 86% satisfactory results in 22 operations

with a minimum follow-up of three years. In our longer

follow-up we found no deterioration with time in this

group.

Other reports have, however, been discouraging

about longer term results (Laskin 1978; Insall and

Aglietti 1980; Cameron ci a!. 1981. Insall reported 64%

of his results to be fain or poor after a five- to seven-year

follow-up and has consequently largely abandoned the

procedure in favour of total joint replacement. He did

find significantly better results from a small number of

lateral compartment replacement operations for valgus

knees. His results may have been influenced by the fact

that 55% ofhis patients had previously undergone patel-

lectomy.

The results ofhigh tibial osteotomy appear to be less

predictable. Many series of osteotomies have been

reported. both prospective and. more often, retrospective

(Tj#{246}rnstrand, Egund and Hagstedt 1981; Vainionp#{228}#{228}et

a!. 1981; Keene and Dyreby 1983: Insall, Joseph and

Msika 1984). Several methods of assesssment have been

used and follow-up has varied from one to 10 years so

that it is difficult to infer overall results from such a

hetenogenous group. Results have varied dramatically

from 97% satisfactory reported by Coventry (1973)

using his own assessment after a one- to nine-year

follow-up. to the 56% fair or poor reported by Harding

(1976), using Merle d’Aubign#{233}’s method of assessment

after a five-month to 12-year follow-up. Our results fall

between these two extremes.

This paper compares the results of two procedures

commonly used to treat unicompartmcntal osteoarthnitis

of the knee. Similar groups of patients and an objective

scoring system used after a long follow-up has allowed a

useful direct comparison. In total, 76% of the unicom-

partmental replacement patients had satisfactory results

whereas only 43% of the osteotomy patients were

equally satisfactory.

At the replacement operations. the unicompart-

mental prostheses were deliberately positioned to under-

connect the deformity, with the aim of reducing the risk of

deterioration of the relatively normal contralateral com-

partment. After medial compartment replacements the

postoperative coronal tibiofemoral angle was between 5

valgus and 6 varus in 85% of the cases. Jones ci al.

(1981) report a failure rate of over 50% after medial

replacements which left the knee in yams: failures were

caused mainly by loosening. Insall and Aglietti (1980)

reported radiological deterioration in the lateral com-

partment in 50% ofcases after correcting vanus knees to

an average position of 4 valgus. We found few cases of

contralateral deterioration and, despite deliberate under-

correction, no case of symptomatic loosening of the

tibial component.

Most previous studies of osteotomy have shown

poor results after operation for degeneration of the

lateral compartment (Shoji and Insall 1973; Tj#{246}nnstrand

ci a!. I 98 1 ) although this was not so in our series. We do,

however, agree with some previous authors (Laskin

1978; Insall and Aglietti 1980) who also found that

patients with lateral compartment arthritis had particu-

larly good results after unicompartmental replacement;

this was impressively shown in the comparison with

patients treated by osteotomy.

A prospective trial is the only conclusive way to

prove the superiority of one procedure oven another but

this study has shown clearly that, in the care of one

group of surgeons, each performing the operation of his

choice. unicompartmental replacement with the St