Soft tissue balancing in total knee replacement

The Knee Vol. 2, No. 1, pp. 27-32, 1995 Copyright 0 1995 Elsev~er Science Ltd Printed in Great Britain. All rights reserved 0261-2194/95 $10.00 + 0.00

Sof% tissue replacement R Johnson, The Wirral Knee L61 IAU. UK

balancing

in total

K Barry, S A G Sampath, Centre,

BUPA

Murrayfield

knee

U Kanitkar

Hospital,

Holmwood

Drive,

Thingwall,

Wirral

Summary We performed 192 Accord total knee replacements, with both components cemented in, between 1983 and 1989. There were 79 rheumatoid arthritic (RA) knees of which 29 (36.7%) required ligament release, and 113 osteoarthritic (OA) knees of which 52 (46.0%) required ligament release at the time of surgery. The results of the four groups, OA and RA with and without ligament release, with a minimum follow up of 4 years, were compared in terms of pain relief, range of movement, flexion deformity, stability and early compljcations. The only significant differences were a greater range of flexion in the RA group with ligament release and greater blood loss in the OA with ligament release group. There were no other significant differences between the groups in either the results or complications. Key words: Total knee replacement, Accord prosthesis, The Knee Vol. 2, No. 1, 27-32, 1995

ligament

Introduction

The bony surfaces in the normal knee contribute to the stability of the joint by their ability to resist compressive loads. The soft tissues alone control movement and resist tensionr. With less constrained total knee replacements, adequate and balanced tension in the soft tissues is essential to ensure prosthetic stability. The design of the Accord prosthesis (Figure 1) incorporates a conical tibia, a cylindrical femoral component and a meniscus which conforms to the femoral component and the upper surface and the conical tibia on its under surface2. Accurate alignment was achieved by a unique system of intramedullary rods on both the femoral and tibia1 sides3. Soft tissue stability was achieved in the anteroposterior plane by equalizing the flexed and extended gaps between the cut surfaces of the femur and the tibia. Asymmetrical coilateral ligament laxity was restored by the appropriate collateral ligament release4. After the bony cuts had been made and the trial femoral and tibia1 components inserted, the indicator as to when to perform soft tissue release was collateral

Accepted: January 1995 Correspondence and r~~~~~~ requests FRCS, The Win-al Knee Centre, Hoimwood Drive, Thingwall, Wirral

io: Mr R Johnson, BUPA Murrayfiefd L61 IAU, UK

MCH

(ORTH)

Hospital,

release, complications

ligament imbalance as indicated by mensical subluxation. If one collateral ligament was tighter than the other, then the meniscus would sublux away from the tight side (Figures 2 and 3). A gradual soft tissue release was then performed on the tight side untili the meniscus was stable (Figure 4). The purpose of this study was to compare the outcome in terms of pain relief, range of movement, flexion deformities, stal$ity, and complications in a group of patients who required ligament releases with the group who did not. Patients and methods

During the period April 1983 to December 1989, 2.59 Accord total knee replacements’, with both components cemented in, were performed; All patients therefore had a minimum follow up of 4 years. Clinical and radiographical assessment of all cases was carried out preoperatively and postoperatively at 6 months, 12 months and annually thereafter. Clinical assessment was recorded on proforma incorporating the Hospital for Special Surgery and British Orthopaedic Association charts enabling results to be recorded as an overall score or as individual parameters. A further chart was used to record operation details. All angular movements were measured using a goniometer. The range of flexion was recorded as

28

The Knee Vol

Figure

1. The

Accord

2 No

1 1995

prosthesis.

1 point per 8” of flexion. Measurements of stability were recorded as recommended by the Knee Society Clinical Ratings Systems5. Measurements of anteroposterior stability were made with the knee flexed to 90” and with the hamstrings relaxed, an anterior drawer test was performed, anteroposterior laxity was recorded as none for 0 to 5 mm, slight as 5 to 10 mm and gross for greater than 10 mm. Valgus or varus deformities were assessedon the preoperative long leg weight bearing films. A varus or valgus deformity was considered to be a 5” or greater deviation from the mechanical axis and neutral between those limits. Of the original 259 patients, there were 48 deaths from unrelated causes, i.e. 18.5% of the population. Therefore, to eliminate any spurious results, any patient who survived more than one year had their latest follow-up results compared with the rest of the groups. Patients were divided into four groups, rheumatoid and osteoarthritic with or without ligament release and a statistical analysis of all the parameters performed.

Figure

2.

Tight

medial

ligament.

osteoarthritic, ligament release; and osteoarthritic no ligament release), were examined using the KruskalWallis Test and the Mann-Whitney U test (range of movement, age blood loss) and the x2 test and Fisher’s exact test (walking pain, resting pain, stability, anteroposterior laxity at 90” flexion, rotation in 90” flexion). The Mann-Whitney test was used in preference to the t-test because the data examined were not consistently normally distributed. The following comparisons were also made with respect to the above outcome measurements: rheumatoid patients versus osteoarthritic patients, between all the ligament release patients versus no ligament release patients, and surviving patients versus non-surviving patients (by diagnostic category). Fisher’s exact test was used to explore differences in the numbers of complications between the ligament release group and the no ligament release group. The significance level (cc) was set at 0.01 throughout; this is somewhat conservative, but is appropriate in view of the number of comparisons being made. Results

Statistical methods used Differences between the four groups (rheumatoid, ligament release; rheumatoid, no ligament release;

The results of the four group, osteoarthritis with ligament release (OAL) or no ligament release (OANL), rheumatoid with ligament release (RAL) or

Johnson

Figure 3. Meniscal IigamenL

Table

1. Median,

subluxation

minimum

away

and maximum

from

Median age (years) age (years) Minimum age (years) maximum

no ligament release (RANL), l-6 and Figures 5-9.

tight

Figure release.

in total knee replacement

4. Meniscus

stable

after

medial

29

collateral

ages (by no. of knees) No ligament

Rheumatoid,

et al.: Soft tissue balancing

release

Ligament

n = 50 Osteoarthritic,

63 26 84

are presented in Tables

We performed 259 knee replacements in 223 patients between 1983 and 1989; 48 patients died from unrelated causes, 8 were lost to follow-up, 6 institutionalized and 4 arthrodesed following deep infection. Therefore, 193 knees were available for review with a minimum follow up of 4 years. The range of follow up was 4 to 7 years, with a mean of 4.8 years. One patient had a diagnosis other than RA or OA and was therefore excluded, leaving 192 knees. There were 113 osteoarthritic knees of which 70 were in women and 43 were in men. Of the 79 rheumatoid knees, 62 were in women and 17 were in men. The average age of all patients was 68.9 years, maximum 84

70 51 81

n = 62 Rheumatoid, 61 37 79

release

n = 29 Osteoarthritic,

n = 51

65 40 82

and minimum 26 years. The median ages of the groups are shown in Table 1. There were 113 OA knees of which 50 (44.2%) required ligament release and 63 (55.8%) did not. There were 79 RA knees of which 29 (36.7%) had a ligament release and 50 (63.3%) did not. There were 66 valgus knees, 70 varus knees and 56 neutral knees. The diagnosis and the numbers requiring ligament releases are shown in Table 2.

Pi&l Figure 5 shows the numbers of knees with residual pain in all groups. There was some evidence that the

The Knee Vol 2 No 1 1995

30

Table

2. Valgus,

varus

and neutral

deformities

and ligament

releases

Diagnosis Rheumatoid

Deformity

n=

Valgus,

No ligament

66

Osteoarthritic

n=

37

Neutral,

n =

Varus,

n = 70

56

25 31

15 55

Figures

in parentheses

release

n = 79

(81.6) (58.6) (38.5) (44.8) (60.0) (60.0)

7 12 15 17 6 22

(18.4) (41.4) (61.5) (55.2) (40.0) (40.0)

are percentages.

Rotation

osteoarthritic knees, with ligament release, had more walking pain, but this was not significant (P = 0.192). There was no significant difference between any of the groups for resting pain (P = 0.481).

in flexion

Figure 6 shows the degree of rotation at 90” flexion and again there was no significant difference between all the groups (P = 0.50).

Range of flexion

Flexion deformity

The range of flexion is shown as one point per 8” flexion. The mean range of flexion is the same in all groups, i.e. 12 points, and the spread is shown in Table 3. The range of flexion was significantly higher in the RAL group compared with the OANL group (P = 0.0057). There were no other significant differences at the 1% level.

Figure 7 shows the propo~ion of patients with flexion deformities. There was no significant difference between the groups (P = 0.6783).

Figures 8 and 9 show the degree of laxity in both the anteroposterior plane measured in millimetres and the valgus-varus plane in degrees. Anteroposterior laxity was considered to be negligible if lessthan 5 mm, slight between 5 and 10 mm and gross if greater than 10 mm. The difference between the groups was not significant (P = 0.014). Similarly Galgus-varus instability showed no significant difference (P = 0.349).

90 80 70 is60 E 2 50 0 40 i 30 20 10 0

Ligament

113

30 17 IO 14 9 33

29

release

i

RANL

OANL

RAL

OAL

a

8 2 B g

90 80 70 60 50 40 30 20 10 0

60 50 $40 ;r :, 30 PP 20 RANL

OANL

RAL

OAL

10

b

0 RANL

Figure

5. (a) Pain on walking; (b) resting pain: E, none; Ci, mild; moderate or severe. OAL had more pain than other gro;ps on walking, P = 0.192; no significant differences in resting pain, P = 0.481. Table Range

3. Range of flexion

OANL

RAL

OAL

Figure 6. Rotation in flexion: II, 30-70”; CJ, 10-30”; 70”. No significant differences between groups: P = 0.050.

of flexion (degrees)

No ligament Rheumatoid,

i‘vledian

12

I3

19 25 6

release

Ligament

n = 50 Osteoarthritic, 12 29 27 6

n = 62

Rheumatoid, 12 10 10 9

release

n = 29 Osteoarthritic, 12 22 23 6

n = 57

Johnson

et al.: Sof? tissue balancing

in total knee replacement

31

Discussion

alignment of the prosthesis in relation to the mechanical axis is essential to the long term survival of total knee replacement@. Bony deformity should be corrected by accurately aligning the components and then by soft tissue release and not by angular bone cuts7-9. Using a system of intramedullary rods, accurate alignment is achieved with this prosthesis with a mean deviation of 0.67” from the mechanical axis”. Having achieved accurate alignment the decision as to whether or not a soft tissue balance needs to be performed, now has to be made. Deformities of the knee are usually a result of bone loss. Some deformities are due to bone loss alone and others a combination of bone loss and collateral ligament contracture . One method of differentiating these two types of deformity is with the CLEFT test (Collateral Ligament Extension-Flexion test). This test involves examining the deformed knee in extension and then flexing the knee. If the deformity, either valgus or varus in extension, disappears when the knee is flexed, then the deformity is purely due to bone loss and a collateral ligament release is not required”. A second and more sensitive method of deciding when collateral releases are required involves the use of the meniscus. The inferior surface of the plastic meniscus conforms to the conical tibia1 component. This provides not only a very sensitive indicator as to when to perform soft tissue releases, but also when equal and adquate soft tissue tension has been achieved. When the meniscus is stable within the tibia1 component during flexion and extension the collateral ligaments are balanced. If one ligament is contracted then subluxation of the meniscus occurs away from the tight side. Correct

RANL

OANL

Figure 7. Flexion deformity: significant differences between

RANL

OANL

RAL

OAL

W, none; 0, some. groups, P = 0.6783.

RAL

NO

OAl

n , negligible 8. Anteroposterior laxity: Figure ((5 mm); c1, slight (5-10 mm); gross (>‘I0 mm). No significant differences between grbups, P = 0.014.

QANL

OANL

FiAL

OAL

Figure 9. Valgus-varus instability: m, none; 0, O-5”; >5”. No significant differences between groups, P = 0.349.

There were no significant differences between the ligament release and no release groups in any of the complications, shown in Table 4. The blood loss figures in Table 5 show a significant increase in the OAL group compared with the RANL group (P = 0.0002). None of the other differences were significant at the 1% level, Of the 48 patients who died, 11 died within the first 12 months, 6 before 2 years, 5 before 3 years, 8 before 4 years, 5 before 5 years, 7 before 6 years, 1 before 7 years and 5 before 8 years. The results of their latest follow-up examination were compared with the rest of the population. Fisher’s exact test was used to compare the dead and alive patients in the four diagnostic groups with respect to walking pain, resting pain, stability, anteroposterior laxity at 90” flexion and rotation in 90” flexion. The only significant differences observed were firstly in anteroposterior laxity at 90” flexion in the osteoarthritic non-ligament release group (P = 0.0081) shown in Table 6 and secondly the range of movement score was significantly higher in the rheumatoid ligament release group than in the osteoarthritic no ligament release group (P = 0.0057).

Table

4. Early complications

Early complications Wound infection Superficial Deep Delayed healing Haematoma Fat embolus Deepvenous thrombosis Pulmonary embolus Cardiovascular accident Cardiac

Stroke Urinary complications Infection Retention Lateral palsy Manipulation required Sublux of meniscus Death Other

No ligament release

Ligament release 1

4 11

4 4 -

-

1

-

-

1 z 2 7.

1 2 2 5

32

The Knee Vol 2 No 1 1995

Table 5. Blood

loss in 100 ml units No ligament

release

n = 50

Osteoarthr~tjc,

Rheumatoid, Median blood loss Minimum blood loss Maximum blood loss P = 0.0021

for OAL

compared

Table 6. Anteroposterior

8 1 25 with

laxity

None (~5 mm) Slight (5-10 mm) Gross (>I0 mm) Fisher’s Values

Ligament n = 6.2 Rheumatoid,

9 0 35

9 0 75

n = 29

release Osteoarthritic,

n = 51

13 0 3%

RANL

References

at 90” fiexion Dead knees

Alive knees

2 (18) 2 (18) 7 (641

39 (63) 21 (34) 2 (97)

1 2

3

exact test, P = 0.0081. in parentheses are percentages.

4

In this series, even with some large deformities, only 41% of the knees required soft tissue releases of one form or another. It is, therefore, in our opinion, essential to make the necessary bone cuts before making any adjustments to the collateral ligaments. The only differences between the groups was an increase in the blood loss in the OAL group and a greater range of flexion in the RAL group. Therefore the results from this series indicate that whether soft tissue balancing has to be performed or not, there were no significant differences in the outcome with a minimum follow up of 4 years. The early and late complications are few in number and there were no significant differences between the groups.

5 6 7

8 9 10

Kapandji IA. Physiology of the Joinfs Vol2. Edinburgh: Churchill Livingstone, 1970: 72-134 Johnson R, Walker CR> Harvey IA, Barry GK, Elloy MA. Five to eight year results of the JohnsonElloy (Accord) total knee arthroplasty. J Arthroplasty 1993; 8: 27-32 Elloy MA, Manning MP, Johnson R. Accuracy of intramedullary alignment in total knee replacement. J RionzedEizg 1992; 14: 363-70 Insall JN. Surgery of the Knee. New York: Churchill Livingstone, 1984: 620-644 Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of The Knee Society Clinical Rating System. Clirz Orthop 1989; 248: 13-14 Jeffery RS, Morris RW, Denham RA. Coronal alignment after total knee replacement. J Bone Joint Surg [Br] 1991; 73B: 709-14 Clayton ML, Thompson TR, Mac RI’. Correction of alignment deformities during total knee arthroplasties. Staged soft tissue releases. Clirl Orthop 1986; 202: 117-24 Dorr LD. Boiardo RA. Technical considerations in total knee arthroplasty. Cf:lin Or~~~~ 1986; 205: 5-11 Laskin RS. Total condylar knee replacement in rheumatoid arthritis. A review of 117 knees. / Booze JoirarSurg [An-z] 1981; 63A: 29-35 JohnsonR, Barry K, MA Elloy. Collateral Ligament Extension-Flexion Test (CLEFT) in total knee replacement. J R Co11Surg Edinb 1994; 39: 127-30