- Email: [email protected]
Outcome and Risk Factors After Anterior Cruciate Ligament Reconstruction: A Follow-up Study of 948 Patients
Outcome and Risk Factors After Anterior Cruciate Ligament Reconstruction: A Follow-up Study of 948 Patients Gauti Laxdal, M.D., Jüri Kartus, M.D., Ph.D., Lars Ejerhed, M.D., Ph.D., Ninni Sernert, R.P.T., Ph.D., Lennart Magnusson, M.D., Eva Faxén, R.P.T., and Jon Karlsson, M.D., Ph.D.
Purpose: The aim of the study was to assess the outcome and risk factors after anterior cruciate ligament (ACL) reconstruction in a large group of patients. Type of Study: Case series. Methods: Included in this retrospective study were 948 patients (323 female, 625 male) with a symptomatic unilateral ACL rupture, who underwent arthroscopic reconstruction using patellar tendon autograft and interference screw fixation at 3 Swedish hospitals. The median age of the patients at the time of the index operation was 26 years (range, 14 to 53 years). The patients underwent surgery at a median of 12 months (range, 0.5 to 360 months) after their injury. Independent physiotherapists performed the follow-up examinations at a median of 32 months (range, 21 to 117 months) postoperatively. Results: Of the 948 patients, 550 (58%) underwent meniscal surgery before, during, or after the ACL reconstruction. The median Tegner activity level was 8 (range, 2-10) before injury, 3 (range, 0-9) preoperatively, and 6 (range, 1-10) at follow-up (P ⬍ .0001 preoperative v follow-up). At follow-up, the median Lysholm score was 90 points (range, 14-100), the median KT-1000 anterior side-to-side laxity difference was 1.5 mm (range, ⫺6 to 13 mm), and the median 1-leg hop test quotient was 95% (0% to 167%) compared with the contralateral normal side. At follow-up, 69.3% of the patients were classified as normal or nearly normal according to the International Knee Documentation Committee evaluation system. However, 36% of the patients were unable to or had severe problems performing the knee-walking test. Inferior results correlated with increased time period between the index injury and reconstruction and concomitant joint damage found at the index operation. Conclusions: Overall, the results were good after ACL reconstruction using patellar tendon autograft and interference screw fixation. Concomitant joint damage and a long time period between the injury and reconstruction are major risk factors for inferior outcome after ACL reconstruction. Level of Evidence: Level IV, case series. Key Words: ACL reconstruction—Patellar tendon—Risk factors—Concomitant injuries.
T
From the Departments of Orthopaedics, Sahlgrenska University Hospital (G.L., J.Kartus, E.F., J.Karlsson), Göteborg;NU-Sjukvården (J. Kartus, L.E., N.S.), Trollhättan/Uddevalla; Fyrbodal Research Institute (J.Kartus, L.E., N.S.), Uddevalla; and Köping Hospital (L.M.), Köping, Sweden. Supported by The Norra A¨lvsborgs and Bohus County Councils Development and Research Fund, and the Swedish National Centre for Research in Sports. Address correspondence and reprint requests to Jon Karlsson, M.D., Ph.D., Department of Orthopaedics, Sahlgrenska University Hospital/Östra, SE-416 85 Göteborg, Sweden. E-mail: jon. [email protected] © 2005 by the Arthroscopy Association of North America 0749-8063/05/2108-4235$30.00/0 doi:10.1016/j.arthro.2005.05.007
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here are few or no subjects in modern orthopaedics that have caused such controversy as that of how to treat the torn anterior cruciate ligament (ACL) in the most optimal way.1-6 The annual incidence of ACL ruptures is estimated at 1 of 3,000 in the general population.7 The treatment of ACL ruptures has changed considerably during the last 10 to 15 years, with a rapid transition from open to arthroscopic techniques. Even though the arthroscopic techniques have led to reduced surgical morbidity and less time away from active sports and leisure time activities, there are still several questions remaining. Despite more than 3,000 scientific publications during the last 4 decades concerning the treatment of ACL ruptures, questions such as the selection of patients for reconstruction of
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 21, No 8 (August), 2005: pp 958-964
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 1.
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The 185 Patients Who Were Excluded Reason for Exclusion
Recurrence of instability during follow-up period due to true reinjury or surgical failures Chondrocyte transplantation during follow-up period Patellar fracture during early rehabilitation period Medial collateral ligament reconstruction during follow-up period More than ⫹1, MCL, LCL, or PCL laxity discovered during surgery (indicating combined injury) Follow-up period less than 21 months Ruptured or reconstructed contralateral ACL or PCL at final follow-up Symptomatic contralateral degenerative knee disease Other reasons
No. of Patients 17 4 1 1
20 5 127 4 6
the ACL and timing of the operation are not fully answered yet.8-13 Therefore, an analysis of factors correlated with the final outcome are of major importance. These factors include the timing of surgery as well as the patient’s age and gender.14-19 Some of the most important fac-
FIGURE 2. patients.
FIGURE 1. patients.
The arthroscopic rear entry technique was used in 94
The endoscopic 1-incision technique was used in 854
tors are probably the influence of concomitant injuries, such as cartilage and meniscal injuries,20 and the time period between the index injury and reconstruction. An undue delay of the ACL reconstruction may lead to an increased number of concomitant injuries, which may secondarily lead to an inferior outcome because of the development of osteoarthrosis in the medium and long term.21-24 The aim of this retrospective study was to evaluate the functional and objective outcome in a large cohort of patients who had undergone ACL reconstruction and to analyze the final results in relation to factors such as age, gender, time between the index injury,
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G. LAXDAL ET AL. TABLE 2.
Objective Results
Lysholm score (points) Paresthesia (cm2) (missing values ⫽ 8) KT-1000 anterior (mm; mean) (missing values ⫽ 1) KT-1000 total (mm; mean) (missing values ⫽ 1) Tegner activity level preinjury (missing values ⫽ 4) Tegner activity level at follow-up (missing values ⫽ 1) Desired Tegner activity level at followup (missing values ⫽ 1) Full ROM (missing values ⫽ 4) LOM extension LOM flexion LOM flexion and extension One-leg hop (% of noninjured side)
90 (14-100) 20 (0-832; mean, 32.9) 1.5 (⫺6 to 13) 1.6 (⫺7 to 11.5) 8 (2-10) 6 (1-10) 7 (2-10) 544/944 (57.6%) 122/944 (12.9%) 165/944 (17.5%) 113/944 (12.0%) 95 (0-167; mean, 92.1) (51 patients could not perform the test)
and reconstruction, as well as concomitant joint damage found at the index operation. METHODS Between September 1991 and November 1999, 1,256 patients underwent primary reconstruction of the ACL at 3 hospitals in Sweden using patellar tendon autograft and interference screw fixation.24 Of those patients, 1,133 (90.5%) were re-examined, with a minimum of 21 months follow-up. The inclusion criteria were as follows: 1. The patients had participated in rehabilitation using an accelerated protocol.25 2. The patients had a contralateral knee with a normal nonruptured ACL at the time of the re-examination. 3. The patients had not reruptured their ACL during the follow-up period nor suffered any other major soft-tissue trauma to the involved lower extremity. 4. The patients had a minimum follow-up period of 21 months after the index operation. 5. The patients had not suffered any fractures on either side before the follow-up examination. 6. The patients had not undergone any additional surgery in either knee before the follow-up examination except for arthroscopies or removal of tibial hardware on the index side. This left a total of 948 patients in the study group. The median age of the patients was 26 years (range, 14
to 53 years; mean, 27.2 years). There were 323 female and 625 male patients. The time period between the index injury and the ACL reconstruction was 12 months (range, 0.5 to 360 months). The patients excluded (n ⫽ 185) and the reasons for their exclusion are presented in Table 1. Surgical Technique The endoscopic 1-incision technique was used in 854 patients and the arthroscopic rear-entry11,26 technique was used in 94 patients (Figs 1 and 2). Concomitant intra- articular injuries, such as meniscal ruptures and cartilage damage, were addressed between the index injury and the follow-up, i.e., either before the reconstruction, at the reconstruction, or during the follow-up period. If no new major trauma had occurred during the follow-up period, the index injury was considered to be responsible for all concomitant joint damage registered, regardless of when it was addressed. Follow-up Examination Six independent observers not involved in the surgical treatment or the rehabilitation of the patients performed the follow-up examinations. The follow-up was based on the Lysholm,27 Tegner,28 and International Knee Documentation Committee (IKDC)29 evaluation systems. The functional performance was evaluated using the 1-leg hop test.30,31 The knee-walking test was used to evaluate the
TABLE 3.
Functional Results
Patellofemoral pain, yes/no Knee-walking test, normal Knee-walking test, unpleasant Knee-walking test, difficult Knee-walking test, impossible IKDC A IKDC B IKDC C IKDC D Patient evaluation, excellent (missing values ⫽ 2) Patient evaluation, good Patient evaluation, fair Patient evaluation, poor Patient expectation, excellent (missing values ⫽ 3) Patient expectation, good Patient expectation, fair Patient expectation, poor
Yes, 294 (31.0%) No, 654 (69.0%) 169 (17.8%) 438 (46.2%) 186 (19.6%) 155 (16.4%) 285 (30.1%) 372 (39.2%) 231 (24.4%) 60 (6.3%) 373 (39.4%) 497 (42.0%) 140 (14.8%) 36 (3.8%) 398 (42.1%) 482 (51.0%) 61 (6.5%) 4 (0.4%)
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 4.
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Correlation Analyses Between Primary Outcome Measures and Baseline Variables
Age Follow-up period Time to reconstruction
Lysholm Score
One-Leg Hop Test
KT-1000 Anterior
Tegner Activity Level
Rho ⫽ 0.01 Rho ⫽ 0.03 Rho ⫽ ⫺0.05
Rho ⫽ ⫺0.09 Rho ⫽ 0.02 Rho ⫽ ⫺0.15
Rho ⫽ ⫺0.003 Rho ⫽ ⫺0.08 Rho ⫽ 0.04
Rho ⫽ ⫺0.28 Rho ⫽ ⫺0.03 Rho ⫽ ⫺0.28
NOTE. Correlation analyses between the primary outcome measures and the most important baseline variables showed that there was an inverse correlation between age and Tegner activity level. The corresponding was also found for the time between the index injury and the ACL reconstruction.
donor-site discomfort and was classified as normal, unpleasant, difficult, or impossible to perform.30,31 The patients were classified as having subjective anterior knee pain if they registered pain during stair walking, sitting with the knee in 90° of flexion, and during or after activity. Range of motion (ROM) was measured using a goniometer graded in single degrees. Loss of motion exceeding 4° in both flexion and extension was registered and categorically classified as loss of motion (LOM).1,11,32,33 The anterior and total side-to-side knee laxity was registered at 89 N, using the KT-1000 arthrometer.34 The patients were asked to subjectively classify the result of the ACL reconstruction as excellent, good, fair, or poor and, correspondingly, to classify to what extent the reconstruction had fulfilled their expectations.31 The area of lost or disturbed anterior knee sensitivity (paresthesia) was measured in square centimeters by palpation by the examiner.30,31 At the final follow-up, the Lysholm score, 1-leg hop test, KT-1000 anterior side-to-side laxity, and the Tegner activity level were considered as the primary outcome measures. The age, gender, time between injury and reconstruction, presence of concomitant joint damage at reconstruction, and the length of the follow-up period were considered as the most important baseline variables. Statistical Analyses The Mann-Whitney U test and the unpaired Student t test were used for the comparison of nonparametric and TABLE 5.
Lysholm score (median points) One-leg hop (mean) KT-1000 anterior (mean) Tegner activity level
parametric data, respectively. In case the comparison involved multiple stratified groups, the Kruskal-Wallis test and analysis of variance were used for the corresponding analysis. The Fisher exact test was used to compare categorical data and the Spearman rank-correlation test was used to analyze correlations between variables within the study group. Note that the values are presented as median (range) unless a mean value is indicated; P ⬍ .05 was considered statistically significant. RESULTS Early reconstruction (within 2 months of the index injury) was performed in 98 patients (10.3%), 428 patients (45.2%) were operated between 2 and 12 months, 316 patients (33.3%) between 12 and 60 months, and 106 patients (11.2%) were operated on later than 60 months. The follow-up examination was performed after 32 months (range, 21 to 117 months). Results of the Lysholm test, disturbance of anterior knee sensitivity (paresthesia), KT-1000 anterior and total laxity measurements, Tegner activity levels, LOM, and the 1-leg hop test are presented in Table 2. The KT-1000 anterior side-to-side measurement was 1.5 mm (range, ⫺6 to 13 mm), and the KT-1000 total side-to-side measurement was 1.6 mm (range, ⫺7 to 11.5 mm). The IKDC classification, the patient’s subjective classification of anterior knee pain, knee-walking ability, and the evaluation and expectation of the results are presented in Table 3. A correlation analysis be-
Influence of Gender
Male
Female
90 (22-100; mean, 88) 92.9 (0-167)% 1.4 (⫺4 to 13) 6 (1-10; mean, 6.5)
90 (14-100; mean, 85) 90.4 (0-132)% 1.7 (⫺6 to 10) 6 (1-10; mean, 5.8)
NOTE. The influence of gender on the primary outcome measures appears to be low.
Significance NS P ⫽ .005 P ⫽ .02 P ⬍ .0001
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G. LAXDAL ET AL. TABLE 6.
Influence of Concomitant Meniscal/Chondral Damage Meniscal/Chondral Damage (n ⫽ 591)
Lysholm score (median, points) One-leg hop (mean, %)* KT-1000 anterior (mean, mm, 1 missing value) Tegner activity level (1 missing value) Loss of extension Loss of flexion
No Damage (n ⫽ 357)
90 (14-100; mean, 86) 91.1 (0-167) 1.6 (⫺6 to 13) 6 (1-10) 30.1% 33.7%
92 (38-100; mean, 89) 93.7 (0-123) 1.3 (⫺5 to 10) 6 (1-10) 16.1% 22.4%
Significance P⫽ P⫽ P⫽ NS P⫽ P⫽
.0054 .0017 .014 .0001 .0002
NOTE. Concomitant joint damage significantly worsened the primary outcome measures. *There were 51 patients who could not perform the test.
tween the primary outcome measures and the baseline variables revealed that there was an inverse correlation between the age and Tegner activity level. An inverse correlation was also found for the time period between injury and reconstruction (Table 4). The influence of gender is presented in Table 5. Meniscal injuries treated between the index injury and the follow-up were registered in 550 patients (58.0%). Correspondingly arthroscopic chondral damage (deeper than superficial fraying) was registered in 131 patients (13.8%) between the index injury and the follow-up. Altogether 591 of the 948 patients (62.3%) were registered as having either meniscal or chondral damage. The data in Table 6 show that patients with concomitant intraarticular joint damage had significantly worse outcome measures than patients without such damage. The influence of timing of reconstruction on the primary outcome is shown in Table 7. During the follow-up period, 219 of the 948 patients (23.1%) underwent additional surgery. The most common procedure was additional arthroscopic meniscectomy, which was performed in 65 patients (6.9%) (Table 8).
TABLE 7. Time of Reconstruction After Injury Lysholm score median (range) points One-leg hop mean (range) % KT-1000 anterior mean, (range) mm Tegner activity level median (range)
DISCUSSION The present study is, to our knowledge, the largest study reporting the results after ACL reconstruction that has been published. We decided to analyze this large cohort in order to detect any risk factors that might correlate with poor outcome after ACL reconstruction.35 The follow-up rate was over 90% and strict exclusion criteria were employed. For instance, all patients with signs of combined knee injuries (other than meniscal and/or chondral injuries) were excluded from the follow-up. One potential weakness of this study was that we chose to exclude the patients who had recurrent instability episodes from the final follow-up. The reason for this is that we do not know whether these patients suffered a true reinjury or actually were surgical failures. Taken together, the results of the present study indicate that the risk of failure in terms of stability was approximately 2%. The principal finding of this study is that the final results were satisfactory in the majority (approximately 90%) of the patients treated. The IKDC was judged as A (normal) or B (nearly normal) in approximately 70%,
The Influence of Timing of Reconstruction on Primary Outcome Measures ⬍2 Months (n ⫽ 98)
2 to 12 Months (n ⫽ 428)
1 to 5 Years (n ⫽ 316)
⬎5 Years (n ⫽ 106)
Significance
94 (35-100) mean, 88 92 (0-114)
90 (22-100) mean, 87 94 (0-132)
90 (22-100) mean, 87 91 (0-167)
90 (14-100) mean, 83 89 (0-126)
P ⫽ .04 P ⫽ .02
1.3 (⫺3 to 10)
1.5 (⫺5 to 13)
1.4 (⫺6 to 11.5)
1.9 (⫺4 to 9)
NS (P ⫽ .17)
7 (2-10)
7 (1-10)
6 (1-10)
5 (1-9)
P ⬍ .0001
NOTE. It appears that the primary outcome measures get worse when the time between the injury and reconstruction increases.
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 8.
Additional Surgery During Follow-up Period
Meniscal procedure ROM deficits Removal of tibial hardware Early lavage due to septic knee Removal of osteophytes, chondral lesions, fibrosis, plicas, loose bodies and other procedures
65/948 (6.9%) 60/948 (6.3%) 43/948 (4.5%) 6/948 (0.6%)
51/948 (5.4%)
NOTE. The most frequent reason for additional surgery was meniscal lesion. Multiple reasons for additional surgery were registered in some patients.
which is well on par with previous studies.1,10,11,35-37 In the patients’ own evaluation, approximately 80% judged the knee as excellent or good, and the patients’ expectations were fulfilled (excellent or good) in approximately 93%. The Tegner activity level at follow-up was 6 (range, 1-10) compared with a preinjury level of 8 (range, 2-10). This drop in activity level has been shown in several other studies,1,16,18,31 and can in fact be considered more or less normal. Many patients do not wish to return to their preinjury activity level, even if possible. This is further supported by the finding that the desired Tegner activity level was 7. An interesting finding was that less than 60% of the patients had regained full ROM of the knee at follow-up. The most serious form of LOM is loss of extension and was registered in almost 13% of the patients (loss of extension only) and 12% (loss of both extension and flexion). In the present study, permanent LOM is correlated with meniscal injuries and chondral damage, as shown in Table 6. This finding has previously been reported by Kartus et al.20 However, Harner et al., Irrgang et al., and Mothadi et al.,38-40 have stated that there is no correlation between associated injuries and LOM. This probably also increases the risk of development of arthrosis in the long run. Another important finding was that 36% of the patients judged kneewalking as difficult or impossible.30,31 It is well known from previous studies that difficulties in kneeling or knee-walking may have significant deleterious effects on functional performance in terms of some occupational and leisure time activities.32 Another graft choice, such as hamstring tendon, might of course have reduced the number of patients with these problems.17,31,35 It should, however, be borne in mind that using the patellar tendon was one of the inclusion criteria of the present study. The correlation analysis including the primary outcome measures showed that there was an inverse correlation between age and Tegner activity level. The same finding was true of the time between the index injury and
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the ACL reconstruction. It was shown that the timing of reconstruction, i.e., delayed reconstruction, had a negative influence on the Tegner activity level. This means that if the patient wants to return to high-level activities, the ACL reconstruction should be performed without undue delay once the swelling has subsided and the ROM is restored.26 Correspondingly, Table 7 shows that patients who underwent an early reconstruction had a higher activity level and Lysholm score at follow-up compared with those who underwent reconstruction later on. Therefore, a long time period between the index injury and the reconstruction must be considered a definite risk factor for inferior results. This should be taken into consideration when different treatment alternatives are discussed. One third of the patients in the present study were female. The influence of gender appeared to be low, which is in accordance with previous studies.18 There was no difference in terms of the Lysholm score, but the Tegner activity level was lower at follow-up in female patients than in male patients. The KT-1000 arthrometer results showed slightly increased values in female patients; however, the difference was less than 0.5 mm, which is hardly clinically relevant. Correspondingly, the 1-leg hop test results had a difference of only 2%. Thus, the female sex cannot be considered to be a risk factor for inferior results after ACL reconstruction. Concomitant meniscal and chondral damage significantly worsened the primary outcome measures. It has previously been shown that concomitant joint damage makes the results after an ACL reconstruction worse and increases the risk of arthrosis in the long run.4,6,21,20,23 Even though there were no major differences, the Lysholm score, 1-leg hop test, KT-1000 laxity measurements, and ROM measurements were all significantly worse at the final follow-up in patients with concomitant injuries. Therefore, both meniscal and chondral injuries should be considered as risk factors for inferior outcome after ACL reconstruction.20 CONCLUSIONS Concomitant joint damage and a long time period between the ACL injury and reconstruction appear to be major risk factors for an inferior outcome after ACL reconstruction. Of note is that age and gender do not seem to have major impact on the outcome. REFERENCES 1. Buss DD, Warren RF, Wickiewicz TL, Galiant BJ, Panariello R. Arthroscopically assisted reconstruction of the anterior cru-
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38. 39. 40.
motion after anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:499-506. Kartus J, Magnusson L, Stener S, Brandsson S, Eriksson BI, Karlsson J. Complications following arthroscopic anterior cruciate ligament reconstruction. A 2-5 year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc 1999;7:2-8. Sachs RA, Daniel DM, Stone ML, Garfein RF. Patello-femoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760-765. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med 1987;15:225-229. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990; 18:292-299. Clancy WG Jr. Arthroscopic anterior cruciate ligament reconstruction with patellar tendon. Tech Orthop 1988;2:13-22. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop 1985;198:43-49. Tegner Y, Lysholm J, Lysholm M, et al. A performance test to monitor rehabilitation and evaluate anterior cruciate ligament injuries. Am J Sports Med 1986;14:156-159. Hefti F, Müller W, Jakob RP, et al. Evaluation of knee ligament injuries with the IKDC form. Knee Surg Sports Traumatol Arthrosc 1993;1:226-234. Sernert N, Kartus J, Köhler K, et al. Analysis of subjective, objective and functional examination tests after anterior cruciate ligament reconstruction. A follow-up of 527 patients. Knee Surg Sports Traumatol Arthrosc 1999;7:160-165. Kartus J, Stener S, Lindahl S, Engström B, Eriksson BI, Karlsson J. Factors affecting donor-site morbidity after anterior cruciate ligament reconstruction using bone–patellar tendon– bone autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:222-228. Brosseau L, Balmer S, Tousignant M, et al. Intra- and intertester reliability and criterion validity of the parallelogram and universal goniometers for measuring maximum active knee flexion and extension of patients with knee restrictions. Arch Phys Med Rehabil 2001;82:396-402. Ekstrand J, Wiktorsson M, Öberg B, Gillqvist J. Lower extremity goniometric measurements: A study to determine their reliability. Arch Phys Med Rehabil 1982;63:171-175. Daniel DM, Stone ML, Sachs M, Malcom LL. Instrumented measurement of anterior knee laxity in patients with acute anterior cruciate ligament disruption. Am J Sports Med 1985; 13:401-407. Eriksson K, Anderberg P, Hamberg P, Olerud P, Wredmark T. There are differences in early morbidity after ACL reconstruction when comparing patellar tendon and semitendinosus tendon graft. A prospective, randomised study of 107 patients. Scand J Med Sci Sports 2001;11:170-177. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg Br 2001;83:348-354. Ejerhed L, Kartus J, Sernert N, Köhler, Karlsson J. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with a two-year follow-up. Am J Sports Med 2003;31:19-25. Harner CD, Irrgang JJ, Paul J, Drinkwater S, Fu F. Loss of motion after anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:499-506. Irrgang JJ, Harner CD. Loss of motion following knee ligament reconstruction. Sports Med 1995;19:150-159. Mohtadi NG, Webster-Bogaert S, Fowler PJ. Limitation of motion following anterior cruciate ligament reconstruction. A case-controlled study. Am J Sports Med 1991;19:620-624.
Purpose: The aim of the study was to assess the outcome and risk factors after anterior cruciate ligament (ACL) reconstruction in a large group of patients. Type of Study: Case series. Methods: Included in this retrospective study were 948 patients (323 female, 625 male) with a symptomatic unilateral ACL rupture, who underwent arthroscopic reconstruction using patellar tendon autograft and interference screw fixation at 3 Swedish hospitals. The median age of the patients at the time of the index operation was 26 years (range, 14 to 53 years). The patients underwent surgery at a median of 12 months (range, 0.5 to 360 months) after their injury. Independent physiotherapists performed the follow-up examinations at a median of 32 months (range, 21 to 117 months) postoperatively. Results: Of the 948 patients, 550 (58%) underwent meniscal surgery before, during, or after the ACL reconstruction. The median Tegner activity level was 8 (range, 2-10) before injury, 3 (range, 0-9) preoperatively, and 6 (range, 1-10) at follow-up (P ⬍ .0001 preoperative v follow-up). At follow-up, the median Lysholm score was 90 points (range, 14-100), the median KT-1000 anterior side-to-side laxity difference was 1.5 mm (range, ⫺6 to 13 mm), and the median 1-leg hop test quotient was 95% (0% to 167%) compared with the contralateral normal side. At follow-up, 69.3% of the patients were classified as normal or nearly normal according to the International Knee Documentation Committee evaluation system. However, 36% of the patients were unable to or had severe problems performing the knee-walking test. Inferior results correlated with increased time period between the index injury and reconstruction and concomitant joint damage found at the index operation. Conclusions: Overall, the results were good after ACL reconstruction using patellar tendon autograft and interference screw fixation. Concomitant joint damage and a long time period between the injury and reconstruction are major risk factors for inferior outcome after ACL reconstruction. Level of Evidence: Level IV, case series. Key Words: ACL reconstruction—Patellar tendon—Risk factors—Concomitant injuries.
T
From the Departments of Orthopaedics, Sahlgrenska University Hospital (G.L., J.Kartus, E.F., J.Karlsson), Göteborg;NU-Sjukvården (J. Kartus, L.E., N.S.), Trollhättan/Uddevalla; Fyrbodal Research Institute (J.Kartus, L.E., N.S.), Uddevalla; and Köping Hospital (L.M.), Köping, Sweden. Supported by The Norra A¨lvsborgs and Bohus County Councils Development and Research Fund, and the Swedish National Centre for Research in Sports. Address correspondence and reprint requests to Jon Karlsson, M.D., Ph.D., Department of Orthopaedics, Sahlgrenska University Hospital/Östra, SE-416 85 Göteborg, Sweden. E-mail: jon. [email protected] © 2005 by the Arthroscopy Association of North America 0749-8063/05/2108-4235$30.00/0 doi:10.1016/j.arthro.2005.05.007
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here are few or no subjects in modern orthopaedics that have caused such controversy as that of how to treat the torn anterior cruciate ligament (ACL) in the most optimal way.1-6 The annual incidence of ACL ruptures is estimated at 1 of 3,000 in the general population.7 The treatment of ACL ruptures has changed considerably during the last 10 to 15 years, with a rapid transition from open to arthroscopic techniques. Even though the arthroscopic techniques have led to reduced surgical morbidity and less time away from active sports and leisure time activities, there are still several questions remaining. Despite more than 3,000 scientific publications during the last 4 decades concerning the treatment of ACL ruptures, questions such as the selection of patients for reconstruction of
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 21, No 8 (August), 2005: pp 958-964
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 1.
959
The 185 Patients Who Were Excluded Reason for Exclusion
Recurrence of instability during follow-up period due to true reinjury or surgical failures Chondrocyte transplantation during follow-up period Patellar fracture during early rehabilitation period Medial collateral ligament reconstruction during follow-up period More than ⫹1, MCL, LCL, or PCL laxity discovered during surgery (indicating combined injury) Follow-up period less than 21 months Ruptured or reconstructed contralateral ACL or PCL at final follow-up Symptomatic contralateral degenerative knee disease Other reasons
No. of Patients 17 4 1 1
20 5 127 4 6
the ACL and timing of the operation are not fully answered yet.8-13 Therefore, an analysis of factors correlated with the final outcome are of major importance. These factors include the timing of surgery as well as the patient’s age and gender.14-19 Some of the most important fac-
FIGURE 2. patients.
FIGURE 1. patients.
The arthroscopic rear entry technique was used in 94
The endoscopic 1-incision technique was used in 854
tors are probably the influence of concomitant injuries, such as cartilage and meniscal injuries,20 and the time period between the index injury and reconstruction. An undue delay of the ACL reconstruction may lead to an increased number of concomitant injuries, which may secondarily lead to an inferior outcome because of the development of osteoarthrosis in the medium and long term.21-24 The aim of this retrospective study was to evaluate the functional and objective outcome in a large cohort of patients who had undergone ACL reconstruction and to analyze the final results in relation to factors such as age, gender, time between the index injury,
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G. LAXDAL ET AL. TABLE 2.
Objective Results
Lysholm score (points) Paresthesia (cm2) (missing values ⫽ 8) KT-1000 anterior (mm; mean) (missing values ⫽ 1) KT-1000 total (mm; mean) (missing values ⫽ 1) Tegner activity level preinjury (missing values ⫽ 4) Tegner activity level at follow-up (missing values ⫽ 1) Desired Tegner activity level at followup (missing values ⫽ 1) Full ROM (missing values ⫽ 4) LOM extension LOM flexion LOM flexion and extension One-leg hop (% of noninjured side)
90 (14-100) 20 (0-832; mean, 32.9) 1.5 (⫺6 to 13) 1.6 (⫺7 to 11.5) 8 (2-10) 6 (1-10) 7 (2-10) 544/944 (57.6%) 122/944 (12.9%) 165/944 (17.5%) 113/944 (12.0%) 95 (0-167; mean, 92.1) (51 patients could not perform the test)
and reconstruction, as well as concomitant joint damage found at the index operation. METHODS Between September 1991 and November 1999, 1,256 patients underwent primary reconstruction of the ACL at 3 hospitals in Sweden using patellar tendon autograft and interference screw fixation.24 Of those patients, 1,133 (90.5%) were re-examined, with a minimum of 21 months follow-up. The inclusion criteria were as follows: 1. The patients had participated in rehabilitation using an accelerated protocol.25 2. The patients had a contralateral knee with a normal nonruptured ACL at the time of the re-examination. 3. The patients had not reruptured their ACL during the follow-up period nor suffered any other major soft-tissue trauma to the involved lower extremity. 4. The patients had a minimum follow-up period of 21 months after the index operation. 5. The patients had not suffered any fractures on either side before the follow-up examination. 6. The patients had not undergone any additional surgery in either knee before the follow-up examination except for arthroscopies or removal of tibial hardware on the index side. This left a total of 948 patients in the study group. The median age of the patients was 26 years (range, 14
to 53 years; mean, 27.2 years). There were 323 female and 625 male patients. The time period between the index injury and the ACL reconstruction was 12 months (range, 0.5 to 360 months). The patients excluded (n ⫽ 185) and the reasons for their exclusion are presented in Table 1. Surgical Technique The endoscopic 1-incision technique was used in 854 patients and the arthroscopic rear-entry11,26 technique was used in 94 patients (Figs 1 and 2). Concomitant intra- articular injuries, such as meniscal ruptures and cartilage damage, were addressed between the index injury and the follow-up, i.e., either before the reconstruction, at the reconstruction, or during the follow-up period. If no new major trauma had occurred during the follow-up period, the index injury was considered to be responsible for all concomitant joint damage registered, regardless of when it was addressed. Follow-up Examination Six independent observers not involved in the surgical treatment or the rehabilitation of the patients performed the follow-up examinations. The follow-up was based on the Lysholm,27 Tegner,28 and International Knee Documentation Committee (IKDC)29 evaluation systems. The functional performance was evaluated using the 1-leg hop test.30,31 The knee-walking test was used to evaluate the
TABLE 3.
Functional Results
Patellofemoral pain, yes/no Knee-walking test, normal Knee-walking test, unpleasant Knee-walking test, difficult Knee-walking test, impossible IKDC A IKDC B IKDC C IKDC D Patient evaluation, excellent (missing values ⫽ 2) Patient evaluation, good Patient evaluation, fair Patient evaluation, poor Patient expectation, excellent (missing values ⫽ 3) Patient expectation, good Patient expectation, fair Patient expectation, poor
Yes, 294 (31.0%) No, 654 (69.0%) 169 (17.8%) 438 (46.2%) 186 (19.6%) 155 (16.4%) 285 (30.1%) 372 (39.2%) 231 (24.4%) 60 (6.3%) 373 (39.4%) 497 (42.0%) 140 (14.8%) 36 (3.8%) 398 (42.1%) 482 (51.0%) 61 (6.5%) 4 (0.4%)
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 4.
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Correlation Analyses Between Primary Outcome Measures and Baseline Variables
Age Follow-up period Time to reconstruction
Lysholm Score
One-Leg Hop Test
KT-1000 Anterior
Tegner Activity Level
Rho ⫽ 0.01 Rho ⫽ 0.03 Rho ⫽ ⫺0.05
Rho ⫽ ⫺0.09 Rho ⫽ 0.02 Rho ⫽ ⫺0.15
Rho ⫽ ⫺0.003 Rho ⫽ ⫺0.08 Rho ⫽ 0.04
Rho ⫽ ⫺0.28 Rho ⫽ ⫺0.03 Rho ⫽ ⫺0.28
NOTE. Correlation analyses between the primary outcome measures and the most important baseline variables showed that there was an inverse correlation between age and Tegner activity level. The corresponding was also found for the time between the index injury and the ACL reconstruction.
donor-site discomfort and was classified as normal, unpleasant, difficult, or impossible to perform.30,31 The patients were classified as having subjective anterior knee pain if they registered pain during stair walking, sitting with the knee in 90° of flexion, and during or after activity. Range of motion (ROM) was measured using a goniometer graded in single degrees. Loss of motion exceeding 4° in both flexion and extension was registered and categorically classified as loss of motion (LOM).1,11,32,33 The anterior and total side-to-side knee laxity was registered at 89 N, using the KT-1000 arthrometer.34 The patients were asked to subjectively classify the result of the ACL reconstruction as excellent, good, fair, or poor and, correspondingly, to classify to what extent the reconstruction had fulfilled their expectations.31 The area of lost or disturbed anterior knee sensitivity (paresthesia) was measured in square centimeters by palpation by the examiner.30,31 At the final follow-up, the Lysholm score, 1-leg hop test, KT-1000 anterior side-to-side laxity, and the Tegner activity level were considered as the primary outcome measures. The age, gender, time between injury and reconstruction, presence of concomitant joint damage at reconstruction, and the length of the follow-up period were considered as the most important baseline variables. Statistical Analyses The Mann-Whitney U test and the unpaired Student t test were used for the comparison of nonparametric and TABLE 5.
Lysholm score (median points) One-leg hop (mean) KT-1000 anterior (mean) Tegner activity level
parametric data, respectively. In case the comparison involved multiple stratified groups, the Kruskal-Wallis test and analysis of variance were used for the corresponding analysis. The Fisher exact test was used to compare categorical data and the Spearman rank-correlation test was used to analyze correlations between variables within the study group. Note that the values are presented as median (range) unless a mean value is indicated; P ⬍ .05 was considered statistically significant. RESULTS Early reconstruction (within 2 months of the index injury) was performed in 98 patients (10.3%), 428 patients (45.2%) were operated between 2 and 12 months, 316 patients (33.3%) between 12 and 60 months, and 106 patients (11.2%) were operated on later than 60 months. The follow-up examination was performed after 32 months (range, 21 to 117 months). Results of the Lysholm test, disturbance of anterior knee sensitivity (paresthesia), KT-1000 anterior and total laxity measurements, Tegner activity levels, LOM, and the 1-leg hop test are presented in Table 2. The KT-1000 anterior side-to-side measurement was 1.5 mm (range, ⫺6 to 13 mm), and the KT-1000 total side-to-side measurement was 1.6 mm (range, ⫺7 to 11.5 mm). The IKDC classification, the patient’s subjective classification of anterior knee pain, knee-walking ability, and the evaluation and expectation of the results are presented in Table 3. A correlation analysis be-
Influence of Gender
Male
Female
90 (22-100; mean, 88) 92.9 (0-167)% 1.4 (⫺4 to 13) 6 (1-10; mean, 6.5)
90 (14-100; mean, 85) 90.4 (0-132)% 1.7 (⫺6 to 10) 6 (1-10; mean, 5.8)
NOTE. The influence of gender on the primary outcome measures appears to be low.
Significance NS P ⫽ .005 P ⫽ .02 P ⬍ .0001
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G. LAXDAL ET AL. TABLE 6.
Influence of Concomitant Meniscal/Chondral Damage Meniscal/Chondral Damage (n ⫽ 591)
Lysholm score (median, points) One-leg hop (mean, %)* KT-1000 anterior (mean, mm, 1 missing value) Tegner activity level (1 missing value) Loss of extension Loss of flexion
No Damage (n ⫽ 357)
90 (14-100; mean, 86) 91.1 (0-167) 1.6 (⫺6 to 13) 6 (1-10) 30.1% 33.7%
92 (38-100; mean, 89) 93.7 (0-123) 1.3 (⫺5 to 10) 6 (1-10) 16.1% 22.4%
Significance P⫽ P⫽ P⫽ NS P⫽ P⫽
.0054 .0017 .014 .0001 .0002
NOTE. Concomitant joint damage significantly worsened the primary outcome measures. *There were 51 patients who could not perform the test.
tween the primary outcome measures and the baseline variables revealed that there was an inverse correlation between the age and Tegner activity level. An inverse correlation was also found for the time period between injury and reconstruction (Table 4). The influence of gender is presented in Table 5. Meniscal injuries treated between the index injury and the follow-up were registered in 550 patients (58.0%). Correspondingly arthroscopic chondral damage (deeper than superficial fraying) was registered in 131 patients (13.8%) between the index injury and the follow-up. Altogether 591 of the 948 patients (62.3%) were registered as having either meniscal or chondral damage. The data in Table 6 show that patients with concomitant intraarticular joint damage had significantly worse outcome measures than patients without such damage. The influence of timing of reconstruction on the primary outcome is shown in Table 7. During the follow-up period, 219 of the 948 patients (23.1%) underwent additional surgery. The most common procedure was additional arthroscopic meniscectomy, which was performed in 65 patients (6.9%) (Table 8).
TABLE 7. Time of Reconstruction After Injury Lysholm score median (range) points One-leg hop mean (range) % KT-1000 anterior mean, (range) mm Tegner activity level median (range)
DISCUSSION The present study is, to our knowledge, the largest study reporting the results after ACL reconstruction that has been published. We decided to analyze this large cohort in order to detect any risk factors that might correlate with poor outcome after ACL reconstruction.35 The follow-up rate was over 90% and strict exclusion criteria were employed. For instance, all patients with signs of combined knee injuries (other than meniscal and/or chondral injuries) were excluded from the follow-up. One potential weakness of this study was that we chose to exclude the patients who had recurrent instability episodes from the final follow-up. The reason for this is that we do not know whether these patients suffered a true reinjury or actually were surgical failures. Taken together, the results of the present study indicate that the risk of failure in terms of stability was approximately 2%. The principal finding of this study is that the final results were satisfactory in the majority (approximately 90%) of the patients treated. The IKDC was judged as A (normal) or B (nearly normal) in approximately 70%,
The Influence of Timing of Reconstruction on Primary Outcome Measures ⬍2 Months (n ⫽ 98)
2 to 12 Months (n ⫽ 428)
1 to 5 Years (n ⫽ 316)
⬎5 Years (n ⫽ 106)
Significance
94 (35-100) mean, 88 92 (0-114)
90 (22-100) mean, 87 94 (0-132)
90 (22-100) mean, 87 91 (0-167)
90 (14-100) mean, 83 89 (0-126)
P ⫽ .04 P ⫽ .02
1.3 (⫺3 to 10)
1.5 (⫺5 to 13)
1.4 (⫺6 to 11.5)
1.9 (⫺4 to 9)
NS (P ⫽ .17)
7 (2-10)
7 (1-10)
6 (1-10)
5 (1-9)
P ⬍ .0001
NOTE. It appears that the primary outcome measures get worse when the time between the injury and reconstruction increases.
ACL RECONSTRUCTION OUTCOME AND RISK FACTORS TABLE 8.
Additional Surgery During Follow-up Period
Meniscal procedure ROM deficits Removal of tibial hardware Early lavage due to septic knee Removal of osteophytes, chondral lesions, fibrosis, plicas, loose bodies and other procedures
65/948 (6.9%) 60/948 (6.3%) 43/948 (4.5%) 6/948 (0.6%)
51/948 (5.4%)
NOTE. The most frequent reason for additional surgery was meniscal lesion. Multiple reasons for additional surgery were registered in some patients.
which is well on par with previous studies.1,10,11,35-37 In the patients’ own evaluation, approximately 80% judged the knee as excellent or good, and the patients’ expectations were fulfilled (excellent or good) in approximately 93%. The Tegner activity level at follow-up was 6 (range, 1-10) compared with a preinjury level of 8 (range, 2-10). This drop in activity level has been shown in several other studies,1,16,18,31 and can in fact be considered more or less normal. Many patients do not wish to return to their preinjury activity level, even if possible. This is further supported by the finding that the desired Tegner activity level was 7. An interesting finding was that less than 60% of the patients had regained full ROM of the knee at follow-up. The most serious form of LOM is loss of extension and was registered in almost 13% of the patients (loss of extension only) and 12% (loss of both extension and flexion). In the present study, permanent LOM is correlated with meniscal injuries and chondral damage, as shown in Table 6. This finding has previously been reported by Kartus et al.20 However, Harner et al., Irrgang et al., and Mothadi et al.,38-40 have stated that there is no correlation between associated injuries and LOM. This probably also increases the risk of development of arthrosis in the long run. Another important finding was that 36% of the patients judged kneewalking as difficult or impossible.30,31 It is well known from previous studies that difficulties in kneeling or knee-walking may have significant deleterious effects on functional performance in terms of some occupational and leisure time activities.32 Another graft choice, such as hamstring tendon, might of course have reduced the number of patients with these problems.17,31,35 It should, however, be borne in mind that using the patellar tendon was one of the inclusion criteria of the present study. The correlation analysis including the primary outcome measures showed that there was an inverse correlation between age and Tegner activity level. The same finding was true of the time between the index injury and
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the ACL reconstruction. It was shown that the timing of reconstruction, i.e., delayed reconstruction, had a negative influence on the Tegner activity level. This means that if the patient wants to return to high-level activities, the ACL reconstruction should be performed without undue delay once the swelling has subsided and the ROM is restored.26 Correspondingly, Table 7 shows that patients who underwent an early reconstruction had a higher activity level and Lysholm score at follow-up compared with those who underwent reconstruction later on. Therefore, a long time period between the index injury and the reconstruction must be considered a definite risk factor for inferior results. This should be taken into consideration when different treatment alternatives are discussed. One third of the patients in the present study were female. The influence of gender appeared to be low, which is in accordance with previous studies.18 There was no difference in terms of the Lysholm score, but the Tegner activity level was lower at follow-up in female patients than in male patients. The KT-1000 arthrometer results showed slightly increased values in female patients; however, the difference was less than 0.5 mm, which is hardly clinically relevant. Correspondingly, the 1-leg hop test results had a difference of only 2%. Thus, the female sex cannot be considered to be a risk factor for inferior results after ACL reconstruction. Concomitant meniscal and chondral damage significantly worsened the primary outcome measures. It has previously been shown that concomitant joint damage makes the results after an ACL reconstruction worse and increases the risk of arthrosis in the long run.4,6,21,20,23 Even though there were no major differences, the Lysholm score, 1-leg hop test, KT-1000 laxity measurements, and ROM measurements were all significantly worse at the final follow-up in patients with concomitant injuries. Therefore, both meniscal and chondral injuries should be considered as risk factors for inferior outcome after ACL reconstruction.20 CONCLUSIONS Concomitant joint damage and a long time period between the ACL injury and reconstruction appear to be major risk factors for an inferior outcome after ACL reconstruction. Of note is that age and gender do not seem to have major impact on the outcome. REFERENCES 1. Buss DD, Warren RF, Wickiewicz TL, Galiant BJ, Panariello R. Arthroscopically assisted reconstruction of the anterior cru-
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