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Effect of ACL reconstruction on meniscal and chondral lesions in the chronic anterior cruciate deficient knee
Copyright
The Knee Vol. 2, No. 4. pp. 201-205. 1995 0 1996 Elsevier Science Ltd. All rights reserved Printed m Great Britain 0968JJl60195 $10.00 + 0.00
PII: S0968-0160(96)00008-7
Effect of ACL reconstruction on meniscal and chondral lesions in the chronic anterior cruciate deficient knee M Barry
I,* , R Thomas
‘Mayday University Mary and Westfield
I**, A Rees’,
Hospital, College,
Thornton London,
B Shafighian
Heath, Surrey; UK
I, M A S Mowbray’
21RC in Biomedical
Materials,
Queen
Summary
‘Second look’ arthroscopy was performed in 129 patients after anterior cruciate ligament reconstruction. Meniscal or chondral lesions noted at the time of reconstruction were subsequently reviewed at the second arthroscopy and any new lesions were also noted. Stabilization of the knee resulted in a significant reduction in the incidence of meniscal injury, however, the incidence of chondral lesions was not significantly altered. Other factors, including increasing patient age, acute subchondral trauma at the time of cruciate rupture and altered knee kinematics both before and after reconstruction may be responsible for the progressive chondral damage noted. Copyright @ 1996 Elsevier Science Ltd.
Key
words:
The Knee
Anterior Vol.
2, No.
cruciate 4, 201-205,
ligament
reconstruction,
meniscus,
surface
1995
Introduction The association between men&al injury and anterior cruciate ligament (ACL) rupture is well established. It is generally accepted that one of the benefits of ACL reconstruction is preservation of the men&ii and therefore preservation of the integrity of the articular surfaces. It has also beeti stated that ACL reconstruction will allow the chondral surfaces to recover as well, but there is little if any objective data in the literature to support this statement. This paper attempts to investigate the role of ACL reconstruction in preserving the meniscii and chondral surfaces. Patients and methods Between 1986 and 1993, 129 patients received an arthroscopy both before and after anterior cruciate reconstruction. Reconstruction was undertaken Iby the senior author (M.A.S.M.) for chronic symptomatic instability of the knee as a result of ACL insufficiency. This group was followed up for a mean of 46.4 ((range Accepted: April 1996 Correspondence and reprint Registrar, West Middlesex TW7 6AF, UK
chondral
requests to: Mr M Barry FRCS, Orthopaedic University Hospital, Isleworth, Middlesex
12-88) months. There were 108 (84%) men and 21 (16%) women. The mean age at the time of surgery was 27.7 (range 17-56) years and the mean interval from injury to surgery was 31.5 (range 6-132) months. The cause of rupture is shown in Figure 1: 86% were sporting injuries. Before reconstruction, clinical evaluation included both Lachman’ and pivot shift’ tests. The pivot shift test was scored as absent, l-l- (tibia1 slip) or 2+ (tibia1 jerk.) Objective functional scoring was obtained using modified Lysholm3 and Tegner scores3. Arthroscopic assessment was performed on all patients at or near the time of ACL reconstruction. The condition of the meniscii and chondral surfaces was noted. Meniscal lesions were treated by partial menisectomy or repair when indicated. Chondral lesions were graded from 0 (normal) to 4 (exposed subchondral bone)4. Postoperatively, clinical examination was performed and objective scoring was obtained as well as a subjective assessmentby the patient. Results were analysed using the unpaired t-test and the x2 test with Yates’s correction if appropriate. Significance was accepted at the P < 0.05 level. Logistic regression and cross-tabular methods were used for multiple variable analysis.
202
The Knee Vol. 2, No. 4, 1995
Other
only four had recurred, two medial and two lateral. One medial meniscal tear was associated with the recurrence of a pivot shift. We found ten (8%) new meniscal tears, six medial and four lateral; one new meniscal flap tear was associated with a recurrent pivot shift. There were no bilateral tears. Logistic regression analysis did not show any correlation between the patient’s age, interval from injury, preoperative meniscal or chondral status and subsequent meniscal trauma after cruciate reconstruction. However cross-tabular statistics demonstrated that operative intervention was a highly significant (P < 0.001) factor in preserving the intact meniscus after reconstruction.
sport
Chondral lesions Figure
1. Cause of anterior
cruciate
ligament
rupture.
Anterior cruciate reconstruction All 129 patients had their anterior cruciate ligaments reconstructed with a prosthetic ligament (ABC Ligament, Surgicraft, Redditch, UK) The ABC ligament is a scaffold type prosthesis and is made up of 24 strands of unit material, composed of either carbon fibre and polyester or polyester alone5. In this series, 110 patients (85%) had the carbon/polyester type and 19 (15%) the polyester/polyester type. The prosthesis was passedthrough a drill hole in the proximal tibia, then through the knee, to exit over the top of the lateral femoral condyle. The implant was held distally with a polysulphone button and proximally with an expanding polysulphone bollard drilled into cortical bone on the lateral femoral shaft. Postoperatively, the majority of patients were managed in a functional brace for 6 weeks, when a rehabilitation program was started. Return to contact sports was discouraged for a year.
At the time of reconstruction, 20 patients (16%) were found to have 24 chondral lesions: 11 were grade 1 lesions, 12 were grade 2 and 1 was grade 3. There were 3 lesions on the patella, 12 on the medial femoral condyle and 9 on the lateral femoral condyle. There was no significant difference in the mean age between those with a chondral lesion (28.9 years) and those without (27.5 years). The mean interval from injury to reconstruction in patients with chondral damage was 34.8 months, which was not significantly longer than those patients with an intact articular surface (30.0 months). Of the 24 chondral lesions identified before reconstruction, 13 (54%) had resolved at the ‘second look’ arthroscopy, 11 were still present and these had all deteriorated as shown in Table 1. There were seven medial and four lateral lesions. However, at ‘second look’ arthroscopy, 34 new
Bilateral
Secondary arthroscopy Arthroscopy was undertaken in all patients at a mean of 24.3 (range 3-78) months after cruciate reconstruction. It was performed both on a routine basis and when indicated clinically and with the informed consent of the patient. A further inspection of the men&ii and chondral surfaces was made as well as an assessmentof the graft and the state of the synovium. Results Meniscal lesions At operation, 63 patients (49%) were found to have 70 meniscal tears (Figure 2). Of the 70 meniscal tears treated pre-operatively, at ‘second look’ arthroscopy,
Figure
l
2. Site of meniscal
tear at initial
arthroscopy.
?zr
Barry Table
1. Grade
of chondral
lesions
present
et al.: Meniscal
Preoperative lesion
Postoperative old lesion
Postoperative new lesion
1
11
0
0
2 3 4
12 1 0
6 4 1
25 9 0
Total
24
11
34
lesions
after ACL reconstruction
203
found. The development of a pivot shift was not significantly associated with the production of a new meniscal tear (x2 test: P = 0.24). In the 33 patients with a pivot shift, five new chondral lesions were found and in the 96 patients with a stable knee, 29 new chondral lesions were identified. Therefore, the development of a pivot shift was not significantly associated with the production of new chondral damage (x2 test: P = 0.09).
in knees -
Chondral grade
and chondral
-
-
Discussion chondral lesions were found in 31 knees: 8 were situated on the patella, 16 on the medial and 10 on the lateral femoral condyles. These new lesions were predominantly grade 2 (Table 1). Again, logistic regression analysis did not show any correlation between patient’s age, interval from injury, preoperative meniscal or chondral status and subsequent chondral lesion after cruciate reconstruction. However, in this instance, cross-tabular statistics demonstrated that operative intervention was not a significant factor in determining the chondral status after reconstruction. Objective scoring At the time of surgery, the mean Lysholm score for the group was 63.5. After ACL reconstruction, the mean Lysholm score had significantly increased to 86.7 (t test: P < 0.0001.) The mean pre-injury Tegner score for the group was 7.1. At operation, the mean score had fallen to 2.9 and after reconstruction, the Tegner score significantly improved to 5.1 (t test: P < 0.0001). The presence of either meniscal or chondral injury before or after reconstruction had no significant effect on either Tegner or Lysholm scores. Pivot shift When reviewed at a mean of 46.4 months, 96 patients (74%) had a stable knee with an absent pivot shift. In the 33 patients with a pivot shift (l+ or 2+) only one new meniscal tear was found and in the 96 patients with a negative pivot shift, nine new men&al tears were
Table
2.
Incidence
of meniscal
Series This series 1996 Aichroth et al. 1991’ Bray and Dandy 198915 Irvine and Glasgow 199216 Mitsou et al. 19908 O’Brien et al. 1991” Rees and Mowbray 1992” Warren and Marshal 19786
tears
in other
reported
Mean interval to surgery
series
from injury (months) 32 64 34 36 29 36 37 ?
In our series, at a mean of 31.5 months after injury, 49% of our patients had sustained a meniscal tear and this figure is in agreement with other quoted figures (Table 2). Of the injured meniscii, 61.5% were on the medial side and 38.5% on the lateral side. We therefore agree with other authors &12 that it is the medial meniscus that is the most susceptible to injury. Shoemaker and Markolfj3 have shown that the medial meniscus is a significant restraint to anterior tibia1 translation in the cruciate deficient knee whilst the lateral meniscus does not seem to play a similar restraining role. This may explain why the medial meniscus is increasingly vulnerable to injury with time. It is generally accepted that in an unstable knee, meniscal trauma increases with times,10-‘2~14-16. Figure 3 is a graph of the cumulative meniscal injury plotted against the time from injury in our series. Logistic regression analysis has shown that the reduction in the incidence of meniscal trauma from 49% before stabilisation to 8% after, was not related to patient age, interval from injury to reconstruction and meniscal or chondral status preoperatively. Crosstabulation analysis confirms that operative intervention was a highly significant factor associated with the reduction of the incidence of men&al injury. We conclude therefore, that stabilization is important if continued meniscal damage is to be avoided. Even in knees with anterior cruciate deficiency, degenerative changes are less likely when the meniscii are intactI and menisectomy in stable knees is associated with long term degenerative changes in the knee”. The relationship between stabilization of the knee and subsequent preservation of the articular surface is
Number
of patients In)
Percentage of meniscal injury
129
49
50 47 100 244 80 131 98
66 45 86 68 68 58 26
204
The Knee Vol. 2, No. 4, 1995
20
40
60
80
100
120
i
140
Interval from ACL injury (months) Figure
3. Cummulative
meniscal
injury
rate.
lessclear. Both Aichroth et a1.9 and Bray and Dandyi showed a reduction in chondral injury rates following stabilization, however, only 44% (Aichroth et al.) and 47% (Bray and Dandy) of their patients who had preoperative arthroscopy, had ‘second look’ arthroscopy and it was not clear in either paper if the chondral lesions that were identified after reconstruction were new or old. In our series, however, all patients had both a pre- and postoperative arthroscopy and any intra-articular pathology was noted on each occasion. Whilst 20 patients (16%) had chondral lesions prior to reconstruction, 31 patients (28%) had developed new chondral lesions after reconstruction. This increase was not due to associated factors such as patient age, interval from injury to reconstruction or meniscal status. Cross-tabulation analysis demonstrated that operative intervention had no effect on subsequent chondral status. Furthermore and surprisingly, the presence or absence of the pivot shift was not a significant factor in determining the condition of the chondral surfaces. Concern has been expressed in the literature” about the theoretical development of damage to the articular cartilage by harmful chondrolytic enzymes produced in the synovium by a giant cell foreign body reaction to particular debris derived from artificial material within the knee. It could, therefore, be argued that the continued chondral damage noted in our patients was simply a result of debris shed by the prosthetic material within their knees. We have investigated and reported on this possibility”’ and we found no statistical association between a chronic giant cell synovitis and the presence of chondral damage. Furthermore, damage to the articular surface in the presence of chondrolytic enzymes would be likely to produce a generalized change in the vitality of the whole of the joint articular surface and therefore changes would be noted at all sites of high contact stress within the knee joint. Our findings, however, showed that chondral lesions were confined to one contact site only, suggesting that a localized mechanical mechanism was responsible.
The increasing rate of chondral lesions in the knee joint following cruciate ligament reconstruction, despite the preservation of meniscal function, is a cause for concern. Persisting adverse mechanical factors, subchondral injury at the time of the ligament rupture, ageing and any or all of these factors may be involved. Vellet et aZ.27 showed that after an acute knee injury, 72% of the patients in their serieshad sustained an occult subchondral fracture. Of these occult fractures, 79% were associated with an ACL rupture. In subsequent follow up, there was a high incidence of osteochondral sequelae. Altered stiffness in the subchondral bone may therefore lead to abnormal stresses and subsequent progressive degenerative changes in the overlying articular cartilage in spite of surgical stabilization. Setton et aZ.22 in a study of the articular cartilage of canine knees following ACL transection found adverse changes in the biochemistry, morphology and mechanical properties of the articular cartilage. In a cadaver study, Cawleyz3 showed that following a bone-patella tendon-bone reconstruction, knee joint kinematics were not normal in spite of the apparent restoration of stability and abolition of the pivot shift. The increasing age of the patient and the time from initial injury to reconstruction may also be a factor in the progression of chondral lesions in our patients. In our series the mean interval from injury to reconstruction was 31.5 (range 6-132) months.
Conclusions Meniscal tears were present in 49% of knees prior to ACL reconstruction, after reconstruction meniscal tears were present in only 8% of knees. ACL reconstruction was a significant factor in reducing the number of meniscal tears. Chondral lesions were present in 16% of knees prior to ACL reconstruction, after reconstruction new chondral lesions were present in 28% of knees. Neither operative intervention nor the presence or absence of a pivot shift was a significant factor in the development of chondral damage. Other causes, such as chronicity of the chondral lesion, associated subchondral trauma at the time of ACL injury and the presence of altered knee kinematics, in spite of apparent operative stabilization, are more likely to be responsible for the progressive chondral changes. The presence of intra-articular pathology before reconstruction had no effect on either the Lysholm or Tegner scores at a mean follow up of 46.4 months after surgery.
Acknowledgements We wish to thank Mr C Fernandez of the Audit Department at the Mayday University Hospital for his assistancewith the logistic regression and cross-tabular statistics.
Barry
et al.: Meniscal
References 1 2 3 4 5
6 7
8
9
10
11
Torg JS, Conrad W, Kalen V. Clinical diagnosis of anterior cruciate ligament instability in the athlete. Am J Sports Med 1976; 4: 84-93 Galway RD, Beaupr6 A, Macintosh DL. Pivot shift: a clinical sign of symtomatic anterior cruciate insufficiency. J Bone Joint Surg[BrJ 1972; 54B: 763-764 Tegner Y, Lysholm J. Rating systems in the evaluation of the knee ligament injuries. Clin Orthop 1985; 198: 43349 Peterson L, RenstrGm P. Sports Injuries. Their Prevention and Treatment. 1st edn. London, UK: Martin Dunitz, 1986 Strover A, Hughes F, O’Brien T, Minns R. Mechanical properties of the ABC carbon and polyester fibre anterior cruciate ligament. Proc Inst Mech Eng (l/K) Engineering in Medicine Meeting. 1989, 97-101 Warren RF, Marshall JL. Injuries of the anterior cruciate and medial collateral ligaments of the knee. Clin Orth 1978; 136: 191-197 Kornblatt I. Warren RF, Wickiewicz TL. Long term follow-up of anterior cruciate reconstruction using the quadriceps tendon substitute for chronic anterior cruciate ligament insufficiency. Am J Sports Med 1988; 16: 444-448 Mitsou A. Vallianatos P, Piskpakis N, Maheras S. Anterior cruciate ligament reconstruction by ove:r-thetop repair combined with popliteus tendon plasty. J Bone Joint Surg[BrJ 1990; 72B: 398-404 Aichroth PM, Pate1 DV, Jones CB, Wand JS. A combined intra- and extra-articular reconstruction using a carbon-dacron composite prosthesis for chronic anterior cruciate instability. Znt Orthop 1991; 15: 2 I 9-227 O’Brien SJ, Warren RF, Pavlov H, Panariello R, W-ickiewicz TL. Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patella ligament. J Bone Joint Surg[,4mj 1991; 73A: 278-286 Rees A, Mowbray M. Meniscal lesions in chronic anterior cruciate ligament deficiency: are they secondary to instability and does reconstruction stop their occurence? J Bone Joint Surg[Br] 1992; 749 (Suppl.): 113
and chondral 12
13
14 15 16 17 18 19
20
21
22
23
lesions
after ACL reconstruction
205
Keene GCR, Bickerstaff D, Rae PJ, Paterson RS. The natural history of meniscal tears in anterior cruciate ligament insufficiency. Am J Sports Med 1993; 21: 672-679 Shoemaker SC, Markolf KL. The role of the meniscus in the anterior-posterior stability of the loaded anterior cruciate deficient knee. J Bone Joint Surg[Am] 1986; 68A: 71-79 Satku K, Kumar VP, Ngoi SS. Anterior cruciate ligament injuries: to counsel or to operate? J Bone Joint Surg [Br] 1986; 68B: 458461 Bray RC, Dandy DJ. Meniscal lesions and chronic anterior cruciate ligament deficiency J Bone Joint Surg [Br] 1989; 71B: 128-130 Irving GB, Glasgow MMS. The natural history of the meniscus in anterior cruciate insufficiency. J Bone Joint Surg [Br] 1992; 74B: 403405 Warren RF. Menisectomy and repair in the anterior cruciate deficient patient. Clin Orthop 1990; 252: 55-63 Lanzer WL, Komenda G. Changes in articular cartilage after menisectomy. Clin Orthop 1990; 252: 4148 Olson EJ, Kang JD, Fu FH, Georgescu HI, Mason GC, Evans CH. The biochemical and histological effects of artificial ligament wear particles: In vitro and in vivo studies. Am J Sports Med 1988; 16: 558-570 Barry M, Thomas S, Rees A, Shafighian B, Mowbray MAS. Histological changes associated with an artificial anterior cruciate ligament. J Clin Pathol 1995; 48: 55&559 Vellet AD, Marks PH, Fowler PJ, Munro TG. Occult post-traumatic osteochondral lesions of the knee: prevelance, classification and short-term sequelae evaluated with MR imaging. Radiology 1991; 178: 271-276 Setton LA, Mow VC, Miiller FJ, Pita JC, Howell DS. Mechanical properties of canine articular cartilage are significantly altered following transaction of the anterior cruiciate ligament J Orthop Res 1994; 12: 451-463 Cawley PW. Knee kinematics and bracing. Presented at: Is knee bracing really necessary? 2nd June 1994, London
The Knee Vol. 2, No. 4. pp. 201-205. 1995 0 1996 Elsevier Science Ltd. All rights reserved Printed m Great Britain 0968JJl60195 $10.00 + 0.00
PII: S0968-0160(96)00008-7
Effect of ACL reconstruction on meniscal and chondral lesions in the chronic anterior cruciate deficient knee M Barry
I,* , R Thomas
‘Mayday University Mary and Westfield
I**, A Rees’,
Hospital, College,
Thornton London,
B Shafighian
Heath, Surrey; UK
I, M A S Mowbray’
21RC in Biomedical
Materials,
Queen
Summary
‘Second look’ arthroscopy was performed in 129 patients after anterior cruciate ligament reconstruction. Meniscal or chondral lesions noted at the time of reconstruction were subsequently reviewed at the second arthroscopy and any new lesions were also noted. Stabilization of the knee resulted in a significant reduction in the incidence of meniscal injury, however, the incidence of chondral lesions was not significantly altered. Other factors, including increasing patient age, acute subchondral trauma at the time of cruciate rupture and altered knee kinematics both before and after reconstruction may be responsible for the progressive chondral damage noted. Copyright @ 1996 Elsevier Science Ltd.
Key
words:
The Knee
Anterior Vol.
2, No.
cruciate 4, 201-205,
ligament
reconstruction,
meniscus,
surface
1995
Introduction The association between men&al injury and anterior cruciate ligament (ACL) rupture is well established. It is generally accepted that one of the benefits of ACL reconstruction is preservation of the men&ii and therefore preservation of the integrity of the articular surfaces. It has also beeti stated that ACL reconstruction will allow the chondral surfaces to recover as well, but there is little if any objective data in the literature to support this statement. This paper attempts to investigate the role of ACL reconstruction in preserving the meniscii and chondral surfaces. Patients and methods Between 1986 and 1993, 129 patients received an arthroscopy both before and after anterior cruciate reconstruction. Reconstruction was undertaken Iby the senior author (M.A.S.M.) for chronic symptomatic instability of the knee as a result of ACL insufficiency. This group was followed up for a mean of 46.4 ((range Accepted: April 1996 Correspondence and reprint Registrar, West Middlesex TW7 6AF, UK
chondral
requests to: Mr M Barry FRCS, Orthopaedic University Hospital, Isleworth, Middlesex
12-88) months. There were 108 (84%) men and 21 (16%) women. The mean age at the time of surgery was 27.7 (range 17-56) years and the mean interval from injury to surgery was 31.5 (range 6-132) months. The cause of rupture is shown in Figure 1: 86% were sporting injuries. Before reconstruction, clinical evaluation included both Lachman’ and pivot shift’ tests. The pivot shift test was scored as absent, l-l- (tibia1 slip) or 2+ (tibia1 jerk.) Objective functional scoring was obtained using modified Lysholm3 and Tegner scores3. Arthroscopic assessment was performed on all patients at or near the time of ACL reconstruction. The condition of the meniscii and chondral surfaces was noted. Meniscal lesions were treated by partial menisectomy or repair when indicated. Chondral lesions were graded from 0 (normal) to 4 (exposed subchondral bone)4. Postoperatively, clinical examination was performed and objective scoring was obtained as well as a subjective assessmentby the patient. Results were analysed using the unpaired t-test and the x2 test with Yates’s correction if appropriate. Significance was accepted at the P < 0.05 level. Logistic regression and cross-tabular methods were used for multiple variable analysis.
202
The Knee Vol. 2, No. 4, 1995
Other
only four had recurred, two medial and two lateral. One medial meniscal tear was associated with the recurrence of a pivot shift. We found ten (8%) new meniscal tears, six medial and four lateral; one new meniscal flap tear was associated with a recurrent pivot shift. There were no bilateral tears. Logistic regression analysis did not show any correlation between the patient’s age, interval from injury, preoperative meniscal or chondral status and subsequent meniscal trauma after cruciate reconstruction. However cross-tabular statistics demonstrated that operative intervention was a highly significant (P < 0.001) factor in preserving the intact meniscus after reconstruction.
sport
Chondral lesions Figure
1. Cause of anterior
cruciate
ligament
rupture.
Anterior cruciate reconstruction All 129 patients had their anterior cruciate ligaments reconstructed with a prosthetic ligament (ABC Ligament, Surgicraft, Redditch, UK) The ABC ligament is a scaffold type prosthesis and is made up of 24 strands of unit material, composed of either carbon fibre and polyester or polyester alone5. In this series, 110 patients (85%) had the carbon/polyester type and 19 (15%) the polyester/polyester type. The prosthesis was passedthrough a drill hole in the proximal tibia, then through the knee, to exit over the top of the lateral femoral condyle. The implant was held distally with a polysulphone button and proximally with an expanding polysulphone bollard drilled into cortical bone on the lateral femoral shaft. Postoperatively, the majority of patients were managed in a functional brace for 6 weeks, when a rehabilitation program was started. Return to contact sports was discouraged for a year.
At the time of reconstruction, 20 patients (16%) were found to have 24 chondral lesions: 11 were grade 1 lesions, 12 were grade 2 and 1 was grade 3. There were 3 lesions on the patella, 12 on the medial femoral condyle and 9 on the lateral femoral condyle. There was no significant difference in the mean age between those with a chondral lesion (28.9 years) and those without (27.5 years). The mean interval from injury to reconstruction in patients with chondral damage was 34.8 months, which was not significantly longer than those patients with an intact articular surface (30.0 months). Of the 24 chondral lesions identified before reconstruction, 13 (54%) had resolved at the ‘second look’ arthroscopy, 11 were still present and these had all deteriorated as shown in Table 1. There were seven medial and four lateral lesions. However, at ‘second look’ arthroscopy, 34 new
Bilateral
Secondary arthroscopy Arthroscopy was undertaken in all patients at a mean of 24.3 (range 3-78) months after cruciate reconstruction. It was performed both on a routine basis and when indicated clinically and with the informed consent of the patient. A further inspection of the men&ii and chondral surfaces was made as well as an assessmentof the graft and the state of the synovium. Results Meniscal lesions At operation, 63 patients (49%) were found to have 70 meniscal tears (Figure 2). Of the 70 meniscal tears treated pre-operatively, at ‘second look’ arthroscopy,
Figure
l
2. Site of meniscal
tear at initial
arthroscopy.
?zr
Barry Table
1. Grade
of chondral
lesions
present
et al.: Meniscal
Preoperative lesion
Postoperative old lesion
Postoperative new lesion
1
11
0
0
2 3 4
12 1 0
6 4 1
25 9 0
Total
24
11
34
lesions
after ACL reconstruction
203
found. The development of a pivot shift was not significantly associated with the production of a new meniscal tear (x2 test: P = 0.24). In the 33 patients with a pivot shift, five new chondral lesions were found and in the 96 patients with a stable knee, 29 new chondral lesions were identified. Therefore, the development of a pivot shift was not significantly associated with the production of new chondral damage (x2 test: P = 0.09).
in knees -
Chondral grade
and chondral
-
-
Discussion chondral lesions were found in 31 knees: 8 were situated on the patella, 16 on the medial and 10 on the lateral femoral condyles. These new lesions were predominantly grade 2 (Table 1). Again, logistic regression analysis did not show any correlation between patient’s age, interval from injury, preoperative meniscal or chondral status and subsequent chondral lesion after cruciate reconstruction. However, in this instance, cross-tabular statistics demonstrated that operative intervention was not a significant factor in determining the chondral status after reconstruction. Objective scoring At the time of surgery, the mean Lysholm score for the group was 63.5. After ACL reconstruction, the mean Lysholm score had significantly increased to 86.7 (t test: P < 0.0001.) The mean pre-injury Tegner score for the group was 7.1. At operation, the mean score had fallen to 2.9 and after reconstruction, the Tegner score significantly improved to 5.1 (t test: P < 0.0001). The presence of either meniscal or chondral injury before or after reconstruction had no significant effect on either Tegner or Lysholm scores. Pivot shift When reviewed at a mean of 46.4 months, 96 patients (74%) had a stable knee with an absent pivot shift. In the 33 patients with a pivot shift (l+ or 2+) only one new meniscal tear was found and in the 96 patients with a negative pivot shift, nine new men&al tears were
Table
2.
Incidence
of meniscal
Series This series 1996 Aichroth et al. 1991’ Bray and Dandy 198915 Irvine and Glasgow 199216 Mitsou et al. 19908 O’Brien et al. 1991” Rees and Mowbray 1992” Warren and Marshal 19786
tears
in other
reported
Mean interval to surgery
series
from injury (months) 32 64 34 36 29 36 37 ?
In our series, at a mean of 31.5 months after injury, 49% of our patients had sustained a meniscal tear and this figure is in agreement with other quoted figures (Table 2). Of the injured meniscii, 61.5% were on the medial side and 38.5% on the lateral side. We therefore agree with other authors &12 that it is the medial meniscus that is the most susceptible to injury. Shoemaker and Markolfj3 have shown that the medial meniscus is a significant restraint to anterior tibia1 translation in the cruciate deficient knee whilst the lateral meniscus does not seem to play a similar restraining role. This may explain why the medial meniscus is increasingly vulnerable to injury with time. It is generally accepted that in an unstable knee, meniscal trauma increases with times,10-‘2~14-16. Figure 3 is a graph of the cumulative meniscal injury plotted against the time from injury in our series. Logistic regression analysis has shown that the reduction in the incidence of meniscal trauma from 49% before stabilisation to 8% after, was not related to patient age, interval from injury to reconstruction and meniscal or chondral status preoperatively. Crosstabulation analysis confirms that operative intervention was a highly significant factor associated with the reduction of the incidence of men&al injury. We conclude therefore, that stabilization is important if continued meniscal damage is to be avoided. Even in knees with anterior cruciate deficiency, degenerative changes are less likely when the meniscii are intactI and menisectomy in stable knees is associated with long term degenerative changes in the knee”. The relationship between stabilization of the knee and subsequent preservation of the articular surface is
Number
of patients In)
Percentage of meniscal injury
129
49
50 47 100 244 80 131 98
66 45 86 68 68 58 26
204
The Knee Vol. 2, No. 4, 1995
20
40
60
80
100
120
i
140
Interval from ACL injury (months) Figure
3. Cummulative
meniscal
injury
rate.
lessclear. Both Aichroth et a1.9 and Bray and Dandyi showed a reduction in chondral injury rates following stabilization, however, only 44% (Aichroth et al.) and 47% (Bray and Dandy) of their patients who had preoperative arthroscopy, had ‘second look’ arthroscopy and it was not clear in either paper if the chondral lesions that were identified after reconstruction were new or old. In our series, however, all patients had both a pre- and postoperative arthroscopy and any intra-articular pathology was noted on each occasion. Whilst 20 patients (16%) had chondral lesions prior to reconstruction, 31 patients (28%) had developed new chondral lesions after reconstruction. This increase was not due to associated factors such as patient age, interval from injury to reconstruction or meniscal status. Cross-tabulation analysis demonstrated that operative intervention had no effect on subsequent chondral status. Furthermore and surprisingly, the presence or absence of the pivot shift was not a significant factor in determining the condition of the chondral surfaces. Concern has been expressed in the literature” about the theoretical development of damage to the articular cartilage by harmful chondrolytic enzymes produced in the synovium by a giant cell foreign body reaction to particular debris derived from artificial material within the knee. It could, therefore, be argued that the continued chondral damage noted in our patients was simply a result of debris shed by the prosthetic material within their knees. We have investigated and reported on this possibility”’ and we found no statistical association between a chronic giant cell synovitis and the presence of chondral damage. Furthermore, damage to the articular surface in the presence of chondrolytic enzymes would be likely to produce a generalized change in the vitality of the whole of the joint articular surface and therefore changes would be noted at all sites of high contact stress within the knee joint. Our findings, however, showed that chondral lesions were confined to one contact site only, suggesting that a localized mechanical mechanism was responsible.
The increasing rate of chondral lesions in the knee joint following cruciate ligament reconstruction, despite the preservation of meniscal function, is a cause for concern. Persisting adverse mechanical factors, subchondral injury at the time of the ligament rupture, ageing and any or all of these factors may be involved. Vellet et aZ.27 showed that after an acute knee injury, 72% of the patients in their serieshad sustained an occult subchondral fracture. Of these occult fractures, 79% were associated with an ACL rupture. In subsequent follow up, there was a high incidence of osteochondral sequelae. Altered stiffness in the subchondral bone may therefore lead to abnormal stresses and subsequent progressive degenerative changes in the overlying articular cartilage in spite of surgical stabilization. Setton et aZ.22 in a study of the articular cartilage of canine knees following ACL transection found adverse changes in the biochemistry, morphology and mechanical properties of the articular cartilage. In a cadaver study, Cawleyz3 showed that following a bone-patella tendon-bone reconstruction, knee joint kinematics were not normal in spite of the apparent restoration of stability and abolition of the pivot shift. The increasing age of the patient and the time from initial injury to reconstruction may also be a factor in the progression of chondral lesions in our patients. In our series the mean interval from injury to reconstruction was 31.5 (range 6-132) months.
Conclusions Meniscal tears were present in 49% of knees prior to ACL reconstruction, after reconstruction meniscal tears were present in only 8% of knees. ACL reconstruction was a significant factor in reducing the number of meniscal tears. Chondral lesions were present in 16% of knees prior to ACL reconstruction, after reconstruction new chondral lesions were present in 28% of knees. Neither operative intervention nor the presence or absence of a pivot shift was a significant factor in the development of chondral damage. Other causes, such as chronicity of the chondral lesion, associated subchondral trauma at the time of ACL injury and the presence of altered knee kinematics, in spite of apparent operative stabilization, are more likely to be responsible for the progressive chondral changes. The presence of intra-articular pathology before reconstruction had no effect on either the Lysholm or Tegner scores at a mean follow up of 46.4 months after surgery.
Acknowledgements We wish to thank Mr C Fernandez of the Audit Department at the Mayday University Hospital for his assistancewith the logistic regression and cross-tabular statistics.
Barry
et al.: Meniscal
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