resulting in a range of less than 10 to 125 degrees21) to change with age ... than thirty years who have a tear of the anterior cruciate ligament will ... the International Knee Ligament Standard Evaluation. Form [Fig. 3]). Informed ... Forty-one right knees and thirty-four left knees were .... millimeters, a value of 3+. The result of ...
Copyright 1998 by The Journal of Bone and Joint Surgery, Incorporated
Reconstruction of the Anterior Cruciate Ligament in Patients Who Are at Least Forty Years Old A LONG-TERM FOLLOW-UP AND OUTCOME STUDY* BY KEVIN D. PLANCHER, M.D., M.S.f, J. RICHARD STEADMAN, M.D.t, KAREN K. BRIGOS, M.B.A.t, AND KIRK S. HUTTON, M.D4, VAIL, COLORADO
Investigation performed at Steadman Hawkins Clinic and Steadman Hawkins Sports Medicine Foundation, Vail
ABSTRACT: The long-term results were reviewed for seventy-two patients (seventy-five knees) who had had a bone-patellar ligament-bone intra-articular reconstruction of the anterior cruciate ligament between August 1984 and May 1992. The mean age of the patients at the time of the operation was forty-five years (range, forty to sixty years). Three patients had a bilateral procedure. The primary mechanisms of injury were accidents that occurred during skiing (thirtytwo knees), tennis (fourteen knees), and soccer (five knees). We analyzed the responses to subjective questionnaires, the functional results, and the objective clinical data. The clinical examination included assessment of the range of motion, performance of Lachman and pivot-shift tests, and measurements with use of a KT1000 arthrometer. All knees were evaluated with use of three common rating scales: that of Lysholm and Gillquist; that of The Hospital for Special Surgery, as modified by Insall et al.; and the International Knee Ligament Standard Evaluation Form. At the latest follow-up evaluation, at a mean of fifty-five months (range, twenty-six to 117 months), three patients reported pain or swelling. No patient reported giving-way or symptoms related to the patellofemoral joint. The mean range of extension was -12 to 6 degrees, compared with -8 to 42 degrees preoperative!^ and the mean range of flexion was 112 to 150 degrees, compared with 52 to 154 degrees preoperatively. Flexion was limited to 112 degrees in one patient, but this was 5 degrees greater than that of the uninvolved knee. Sixty knees (80 per cent) had a negative pivot-shift test, and ten knees (13 per cent) had a grade •Although none of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, foundation, educational institution, or other non-profit organization with which one of the authors (J. R. S.) is associated. No funds were received in support of this study. tSteadman Hawkins Clinic (K. D. P. and J. R. S.) and Steadman Hawkins Sports Medicine Foundation (K. D. P., J. R. S., and K. K. B.), 181 West Meadow Drive, Suite 1000, Vail, Colorado 81657. Please address requests for reprints to Dr. Plancher. ISports Medicine Center, University of Nebraska Medical Center, 2255 South 1.32nd Street, Omaha, Nebraska 68144.
184
of 1+. On testing with the KT-1000 device at maximum manual pressure, the mean difference between the injured and uninjured knees was found to have improved by 5.1 millimeters, from 6.4 millimeters preoperatively to 1.4 millimeters postoperatively (p < 0.01). The grade on the International Knee Ligament Standard Evaluation Form improved markedly; seventytwo knees (96 per cent) had a grade of C or D preoperatively, whereas seventy knees (93 per cent) had a grade of A or B postoperatively. The Hospital for Special Surgery score improved from a mean of 69 points preoperatively to a mean of 92 points postoperatively (p < 0.01). The mean score according to the scale of Lysholm and Gillquist increased from a mean of 63 points preoperatively to a mean of 94 points postoperatively (p < 0.01). All patients indicated that they were pleased with the result of the procedure. Bicycling was resumed at a mean of four months; jogging, at a mean of nine months; skiing, at a mean of ten months; and tennis, at a mean of twelve months. The treatment of a torn anterior cruciate ligament in patients who are more than forty years old remains controversial. Recent studies have suggested that a return to the preinjury level of activity results in a substantial rate of reinjury in patients who are managed non-operatively61016. Studies also have shown that use of a brace has not been effective in decreasing the rate of reinjury61034. Most clinicians use non-operative treatment for injuries of the anterior cruciate ligament in patients who are more than forty years old. Most surgeons are concerned that operative reconstruction of the anterior cruciate ligament in this age-group is associated with a higher rate of arthrofibrosis and a resultant decrease in the arc of motion. The reported rates of arthrofibrosis have varied. Strum et al.45, in 1990, found the lesion in 35 per cent (eleven) of thirty-one patients who had had an acute injury of the anterior cruciate ligament and were between the ages of twelve and forty-five years as well as in 12 per cent (fifteen) of 125 patients who had had a chronic injury. Harner et al.21 reported a rate of 11 per cent (twenty-seven of 244) in a group of younTHE JOURNAL OF BONE AND JOINT SURGERY
185
R E C O N S T R U C T I O N OF T H E A N T E R I O R CRUCIATE LIGAMENT No. of Patients
40-45
46-50
51-55
56-60
Years of Age FIG. 1
Graph showing the age distribution of the patients at the time of reconstruction of the anterior cruciate ligament.
ger patients (mean age, twenty-six years). Fisher and Shelbourne", in 1993, reported a rate of 4 per cent (forty-two of 959), and Sachs et al.41 reported a rate of 24 per cent (thirty of 126). Our experience with eighty patients who had an acute injury of the anterior cruciate ligament and were between the ages of fifteen and fifty years revealed a rate of arthrofibrosis of 8 per cent (six patients); the rate was 9 per cent (seven) of eighty patients who had a chronic injury and were between the ages of fourteen and forty-nine years. We have not found the rate of arthrofibrosis (defined as postoperative loss of motion resulting in a range of less than 10 to 125 degrees21) to change with age, and we do not believe that the rate is too high to prohibit operative reconstruction of the anterior cruciate ligament. The lack of published data concerning patients older than forty years and the reports of arthrofibrosis after operative treatment in the 1980s encouraged physicians to recommend that such patients change their athletic lifestyle and use an appro-
priate knee brace. Although the assumption is controversial, many orthopaedists believe that patients older than thirty years who have a tear of the anterior cruciate ligament will have an excellent prognosis if they modify their activity46. In the current study, a group of highly motivated, mature athletes did not want to change their level of activity after sustaining a tear of the anterior cruciate ligament. Thirty-seven (49 per cent) of the seventy-five knees had been treated non-operatively by other physicians, and the patients became dissatisfied with the performance of the knee over time. The mean interval between the injury and the operation was 194 weeks, although fourteen knees were operated on within twenty-one days after the injury. After the other options available for treatment were discussed with the patients, they were offered a reconstruction of the ligament with a chance to return to the preinjury level of activity. The patients had a full understanding of the lengthy postoperative rehabilitation protocol before they signed the consent form. The purpose of the current paper is to report the long-term results after reconstruction of the anterior cruciate ligament in patients who were between the ages of forty and sixty years. Materials and Methods The records of seventy-five patients (seventy-eight knees) who were forty to sixty years old (mean, fortyfive years old) when they had a reconstruction of the anterior cruciate ligament were reviewed (Fig. 1). All operative procedures were performed by the senior one of us (J. R. S.) between August 1984 and May 1992. A bone-patellar ligament-bone graft from the ipsilateral knee was used in all procedures. An open arthrotomy was performed routinely before 1987; this was replaced with an arthroscopic two-incision technique in
Skiing (32) 43%
Tennis (14)19%
^
\\
Basketball or Football (4) 5%
Soccer (5) 7%
^k
Fall (5) 7%
Other (n=15)
Other (15) 20%
Hiking (3) IVlotor-Veh. / Ace. / (3) /
^^Hlii>
Jogging (2)
\ Racquetball
1 Volleyball (3)
Gymnastics (2)
FIG. 2
Graph showing the mechanisms of injury for the seventy-five knees. VOL. 80-A, NO. 2, FEBRUARY 1998
(1) Bicycling (1)
186
K. D. PLANCHER, J. R. STEADMAN, K. K. BRIGGS, AND K. S. HUTTON
1987. Eighteen knees had augmentation of the reconstruction with an extra-articular iliotibial-band tenodesis. The tenodesis was performed routinely in all patients until 1990. The data that were analyzed included the mechanism of injury, the interval between the injury and the operation, the preoperative subjective findings, the results of objective clinical examination, and information obtained with use of three knee-rating scales (that of The Hospital for Special Surgery, as modified by Insall et al.23; that of Lysholm and Gillquist30; and the International Knee Ligament Standard Evaluation Form [Fig. 3]). Informed consent was obtained from all patients before operative intervention. Seventy-two (96 per cent) of the seventy-five patients were available for the clinical follow-up, and two of us (K. D. P. and K. S. H.) traveled independently around the country to several central locations to examine them. There were forty-two men and thirty women. Three patients (two women and one man) had a bilateral injury. Forty-one right knees and thirty-four left knees were involved. The mean duration of follow-up was fifty-five months (range, twenty-six to 117 months). The primary mechanisms of injury were accidents that occurred during skiing (thirty-two knees), tennis (fourteen knees), and soccer (five knees). The other injuries were sustained as a result of a basketball or football accident, a fall from a height, or some other mechanism (Fig. 2). Fourteen knees had an acute injury — that is, they were treated with the index operation within twenty-one days. The remaining sixty-one knees had a chronic tear of the anterior cruciate ligament. Thirty-four of these sixty-one knees had had another type of operative procedure, and a subsequent reinjury, before the reconstruction of the anterior cruciate ligament. Thirty-six patients (thirty-seven knees) had previously consulted with one to four other physicians, who had recommended non-operative treatment. The mean interval between the injury and the operation was 194 weeks (range, two days to 1196 weeks) for the seventy-five knees. The fourteen knees that had an acute injury were operated on at a mean (and standard deviation) of 9.6 ± 4.6 days (range, two to twenty-one days). Six of these knees were operated on within seven days after the injury; seven knees, between eight and fourteen days; and one knee, between fifteen and twenty-one days. The sixty-one knees that had a chronic injury had the index operation at a mean of 1667 ± 1871 days (range, twenty-five days to twentythree years). Twelve of these knees were operated on between twenty-five days and less than three months; four, between three months and less than six months; six, between six months and less than one year; five, between one year and less than two years; and thirtyfour, at two years or more. Eleven knees had an isolated tear of the anterior cruciate ligament, and sixty-four had associated lesions identified at the time of the reconstruction of the ante-
TABLE I KNEE-SCORING SCALE OF LYSHOLM AND GILLQUIST 30
Category
No. of Points
Limp (5 points) None Slight or periodica] Severe or constant
5 3 0
Support (5 points) None Stick or crutch Weight-bearing impossible
5 2 0
Locking (15 points) No locking and no catching sensation Catching sensation but no locking Occasional locking Frequent locking Locked joint on examination
15 10 6 2 0
Instability (25 points) No giving-way Rarely during athletics or other strenuous exertion Frequently during athletics or other strenuous exertion Occasionally in daily activities Often in daily activities With every step
25 20 15 10 5 0
Pain (25 points) None Inconstant and slight during strenuous exertion Marked during strenuous exertion Marked on or after walking more than 2 km Marked on or after walking less than 2 km Constant
25 20 15 10 5 0
Swelling (10 points) None On strenuous exertion On ordinary exertion Constant
10 6 2 0
Stair-climbing (10 points) No problems Slightly impaired One step at a time Impossible
10 6 2 0
Squatting (5 points) No problems Slightly impaired Not beyond 90 degrees Impossible
5 4 2 0
rior cruciate ligament. Sixteen knees had an abnormality of the medial meniscus, which included degenerative disease in three and a tear in twelve; the remaining knee had had a medial meniscectomy. Six knees had a tear of the lateral meniscus. Nine knees had abnormalities of both the medial and the lateral meniscus, which included a tear in seven knees and degenerative disease in one; one knee had had a lateral and medial meniscectomy. A chondral defect was noted in fifteen knees; the defect was grade II in two knees, grade III in two, and grade IV in six, according to the system described by Outerbridge38. Of the remaining five knees with a chondral defect, two had degenerative joint disease in all compartments and three had chondromalacia patellae. Sixteen knees had both a meniscal abnormality and THE JOURNAL OF BONE AND JOINT SURGERY
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TABLE II KNEE-RATING SCALE OF T H E HOSPITAL FOR SPECIAL SURGERY AS MODIFIED BY INSALL ET AL. 23
Category Pain (30 points) No pain at any time No pain on walking Mild pain on walking Moderate pain on walking Severe pain on walking No pain at rest Mild pain at rest Moderate pain at rest Severe pain at rest Function (22 points) Walking and standing unlimited Walking distance of 5-10 blocks and standing ability intermittent (25°
n
6 to 10 mm
°
>10mm
°
Soft
3 to 5 mm
D
6 to 10 mm
D
>10 mm
6 to 10 mm
4. Ligament evaluation (manual, instrumented, radiographic)* Lachman test
D
- 1 to 2 mm
End point
D
Firm
Total anteroposterior translation
D
0 to 2 mm
D
Posterior sag
° 0 to 2 mm
0
3 to 5 mm
D
Medial joint opening
D
D
3 to 5 mm
° 6 to 10 mm
a
Lateral joint opening
a
0 to 2 mm
°
3 to 5 mm
D
6 to 10 mm
a
>10 mm
Pivot shift
D
Equal
° 1 + (glide)
D
2+ (clunk)
D
3+ (gross instability)
Reverse pivot shift
°
Equal
°
D
Marked
°
Severe
0 to 2 mm
° 3 to 5 mm
Glide
a >10 mm >10 mm
FINAL SCORE
A °'B
D
5. Compartmental findings* Crepitus, patellofemoral
D
None
D
Moderate
D
Crepitation with mild pain
D
Crepitation with >mild pain
Crepitus, medial compartment
D
None
D
Moderate
D
Crepitation with mild pain
D
Crepitation with >mild pain
Crepitus, lateral compartment
D
None
°
Moderate
D
Crepitation with mild pain
D
Crepitation with >mild pain
D
None
a Mild
°
Severe
6. Symptoms at donor site
°
Moderate
FIG. 3 The 1993-1994 International Knee Ligament Standard Evaluation Form. The lowest grade within a group determined the group grade. The final score was the worst group grade among the first four groups. * = difference between the value for the involved knee and the value that is (or is assumed to be) normal. (Modified from a form provided by the International Knee Documentation Committee; available from the American Orthopaedic Society for Sports Medicine.)
assisted technique for reconstruction with a bonepatellar ligament-bone graft from the ipsilateral limb. The preferred technique has been described in detail by Steadman and Seemann44. Extra-Articular lliotibial-Band
Tenodesis
Eighteen knees had, in addition, an extra-articular iliotibial-band tenodesis. This procedure was used often by the senior one of us before 1990. All eight knees that had the reconstruction before 1987 and eight of the
twenty-three that had it between 1987 and 1990 had an iliotibial-band tenodesis. Of the remaining forty-four knees, which were treated after 1990, only two had an iliotibial-band tenodesis. We no longer consider this additional procedure to be necessary. This technique involved obtaining a 1.2-millimeter strip of iliotibial band and leaving a proximally based pedicle. The strip then was secured to the posterolateral aspect of the femur, where the bone had been abraded, with use of a guidepin and reamer. The ideal position was achieved when THE JOURNAL OF BONE AND JOINT SURGERY
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the graft was taut with the knee in both flexion and extension. The graft was secured with use of sutures placed over a screw and washer. Postoperative Program Postoperative management included use of a continuous passive-motion device (Sutter, San Diego, California), beginning with 30 to 70 degrees of motion; the motion was increased as tolerated for forty-eight hours while the patient was in the hospital. Intensive physical therapy with passive range-of-motion exercises was begun on the morning after the operation. Our rehabilitation protocol emphasizes early return of motion and immediate weight-bearing as tolerated. Use of crutches was discontinued when the patient could walk without a limp. A Sentry brace (Innovation Sports, Irvine, California) or an equivalent brace was placed on the knee immediately postoperatively. The brace was removed only to allow unrestricted passive range-of-motion exercises during the first six weeks postoperatively. A surface cryotherapy device was used in the hospital, and anti-inflammatory drugs were administered for thirty days after the operation to help control pain and any effusion. All patients were taught to use a standardized, self-monitored rehabilitation program and were discharged with written guidelines, instructions, and an exercise timetable, designed by the senior one of us. Complications All patients were interviewed with regard to any postoperative complications. They were considered to have had a reinjury when there had been a serious event that led to knee pain, effusion, damage to the tendon or ligament, or fracture and that often interfered with activities of daily living. Statistical A nalysis Descriptive statistical analysis of variant testing and chi-square analysis were used as applicable. Statistical
189
significance was established at p < 0.01. Data were stored in a dBase-IV database (Borland International, Scotts Valley, California). Spearman rank-correlation coefficients were derived among continuous variables as many were ordinal scores. Associations between categorical variables were assessed with use of chi-square tests or, if assumptions were not met, with use of exact tests; if a categorical variable was intrinsically ordinal, a Mantel-Haenszel chi-square test was used. Wilcoxon rank-sum and Kruskal-Wallis tests were used to determine differences in continuous variables among groups. To determine the association between a covariate and the interval to subsequent operative intervention, proportional-hazards models were derived and assumptions were assessed. All tests of significance were two-tailed and were performed with use of an alpha error of 0.01. Results Subjective Results Preoperatively, sixty (80 per cent) of the seventyfive knees had pain and swelling and fifty-five (73 per cent) had giving-way. The follow-up questionnaires revealed occasional pain and swelling in three knees. None of these three knees had a procedure in addition to the index operation. Two of the patients had a torn anterior cruciate ligament in the contralateral knee. The third patient had a Workers' Compensation claim pending. None of the seventy-two patients reported giving-way in the involved knee. Anti-inflammatory medication was used by thirtyfive patients preoperatively and was still being used postoperatively by seven. Three of these patients used the medication before participation in sports, and four used it as a precaution although they never had any swelling. Fifty-one patients continued to wear a brace for high-risk pivoting or twisting sports because of fear of reinjury although they never had giving-way of the knee. The patients who had discontinued use of the brace by the time of the latest follow-up evaluation stated that they had worn the brace for a mean of sixteen months postoperatively. Objective Results
Lysholm Score
HSS Score
4 Graph showing the results of the modified Hospital for Special Surgery (HSS)23 and Lysholm and Gillquist30 knee-rating scales. The I-bars indicate the 95 per cent confidence intervals, and the p values indicate a significant difference between the preoperative and postoperative scores. FIG.
VOL. 80-A, NO. 2, F E B R U A R Y 1998
The mean Lysholm and Gillquist score30 before the operation was 63 points (range, 11 to 100 points); this score improved to a mean of 94 points (range, 69 to 100 points) postoperatively (p < 0.01) (Fig. 4). Changes in the score were correlated with changes in The Hospital for Special Surgery scores (r = 0.52). The mean Hospital for Special Surgery score at the time of the initial presentation was 69 points (range, 16 to 98 points); this score improved to a mean of 92 points (range, 74 to 100 points) postoperatively, and the difference was significant (p < 0.01) (Fig. 4). According to this scoring system, fifty-two knees (69 per cent) had an excellent result, twenty-one (28 per cent) had a good
190
K. D. P L A N C H E R , J. R. STEADMAN, K. K. BR1GGS. AND K. S. HUTTON
TABLE III RESULTS OF THE LACHMAN AND PIVOT-SHIFT TESTS PREOPERATIVELY AND AT THE LATEST FOLLOW-UP EVALUATION
Test Lachman Preop. grade Postop. grade No. of knees Pivot-shift Preop. grade Postop. grade No. of knees
0 0 0
1+ 0 3
1+ 1+ 3
2+ 0 21
2+ 1+ 19
2+ 2+ 1
3+ 0 10
3+ 1+ 15
3+ 2+ 3
3+ 3+ 0
0 0 3
1+ 0 6
1+ 1+ 4
2+ 0 28
2+ 1+ 5
2+ 2+ 2
3+ 0 23
3+ 1+ 1
3+ 2+ 3
3+ 3+ 0
result, and two (3 per cent) had a fair result. The postoperative score was significantly better for the knees that had not had a previous operation than for those that had (p < 0.01). The interval between the injury and the operation was inversely correlated with The Hospital for Special Surgery score at the time of followup (r = 0.26); longer intervals were associated with lower scores. The patients also were evaluated with use of the 1993-1994 International Knee Ligament Standard Evaluation Form. Preoperatively, seventy-two knees (96 per cent) were considered abnormal; thirty-nine (52 per cent) had a grade of D, thirty-three (44 per cent) had a grade of C, and three (4 per cent) had a grade of B. The scores improved markedly after the reconstruction, with seventy knees (93 per cent) now considered normal or nearly normal. Twenty-one (28 per cent) had a grade of A; forty-nine (65 per cent), a grade of B; and five (7 per cent), a grade of C. Improvement by at least one grade was noted in seventy knees; forty-six knees had an improvement of at least two grades, and only five had a grade that remained unchanged. Eleven knees improved from a grade of D to a grade of A; twenty-six, from a grade of D to a grade of B; two, from a grade of D to a grade of C; twenty-one, from a grade of C to a grade of B; nine, from a grade of C to a grade of A; and one, from a grade of B to a grade No. of knees
IA
50
ms n c CJD
40
30 20
10 0
1
1
Preop.
JHMLL_L_1-« Postop.
Acute Injuries
Preop.
Postop.
Chronic Injuries
FIG. 5 Graphs comparing the grades on the International Knee Ligament Standard Evaluation Form between the knees that had an acute
injury and those that had a chronic injury.
of A. Three knees maintained a grade of C and two, a grade of B. The knees that had had an acute injury were compared with those that had had a chronic injury (Fig. 5). Before the operation, one of the fourteen acutely injured knees had had a grade of B; one, a grade of C; and twelve, a grade of D compared with two (3 per cent), thirty-two (52 per cent), and twenty-seven (44 per cent) in the chronically injured group. Postoperatively, four knees that had had an acute injury had a grade of A; nine, a grade of B; and one, a grade of C compared with seventeen (28 per cent), forty (66 per cent), and four (7 per cent) in the chronically injured group. Thus, the two groups had similar improvement in the International Knee Ligament Standard Evaluation Form scores. In contrast, we found that the more acute the injury, the greater the change in The Hospital for Special Surgery score. Chronic injuries were significantly associated with lower postoperative Hospital for Special Surgery scores and with higher preoperative values as measured with the KT-1000 device (p < 0.01 for both). The preoperative Lachman values were 1+ for six knees (8 per cent), 2+ for forty-one knees (55 per cent), and 3+ for twenty-eight knees (37 per cent). The pivotshift test was graded preoperatively as 0 for three knees (4 per cent), 1+ for ten knees (13 per cent), 2+ for thirty-five knees (47 per cent), and 3+ for twenty-seven knees (36 per cent) (Table III). Postoperatively, the Lachman values were 0 or 1+ for seventy-one knees (95 per cent) and 2+ for four knees (5 per cent) (Table III). The pivot-shift test was 0 for sixty knees (80 per cent), 1+ for ten knees (13 per cent), and 2+ for five knees (7 per cent). Four knees had no improvement in the Lachman score, and six that had had a positive pivotshift test preoperatively had no change after the reconstruction although they remained asymptomatic. As measured with the KT-1000 arthrometer at maximum manual pressure, the mean difference (and standard deviation) in preoperative displacement, compared with the contralateral side, was 6.4 ± 3.1 millimeters for the seventy-three knees in which it was tested. Sixtyone (84 per cent) of these knees had a mean difference of three millimeters or more. These data are consistent with values that were previously reported in a study of disruption of the anterior cruciate ligament5•12J\ PostTHE JOURNAL OF BONE AND JOINT SURGERY
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operatively, the difference in displacement, measured for all seventy-five knees, improved to a mean of 1.4 ± 3.3 millimeters. Fifty knees (67 per cent) had a difference of less than three millimeters (Table IV). The mean difference between the preoperative and postoperative values was 5.1 millimeters (p < 0.01). No significant difference was detected, with the numbers available, between the postoperative difference in knees that had had an extra-articular iliotibial-band procedure and those that had had only an intra-articular reconstruction. Four knees had a residual difference that was greater than four millimeters (Figs. 6-A and 6-B); two of these knees had a postoperative decrease in the difference, one had an unchanged value, and one had an increase. The interval between the injury and the operation was inversely correlated with the change in the
191
difference in displacement on testing with the KT-1000 arthrometer. Preoperatively, the range of motion was a mean of 1 degree of extension (range, 8 degrees of hyperextension to 42 degrees of extension) and 125 degrees of flexion (range, 52 to 154 degrees). Postoperatively, the mean values improved to 2 degrees of hyperextension (range, 12 degrees of hyperextension to 6 degrees of extension) and 136 degrees of flexion (range, 112 to 150 degrees). One knee flexed to less than 125 degrees postoperatively; however, the value of the arc of flexion of 112 degrees was greater than that of 107 degrees for the uninjured knee. Patellofemoral crepitation was noted in twenty knees preoperatively and in twenty-five knees at the time of the latest follow-up evaluation. No patient re-
No. of knees
0
1
2
3
4
5
6
7
8
9
10 11 12
13 14
15 16 17 18
Millimeters of R/L Displacement Difference FIG. 6-A Figs. 6-A and 6-B: Histograms showing the side-to-side differences in displacement as measured with the KT-1000 arthrometer at maximum manual pressure. Fig. 6-A: Preoperative displacement as measured for seventy-three knees.
No. of knees 14 12 10 8 6 4
1
2
3
•• •• • 4
5
6
7
8
9
10 11 12
13 14
15 16 17 18
Millimeters of R/L Displacement Difference FIG. 6-B
Postoperative displacement as measured for all seventy-five knees. VOL. 80-A, NO. 2, FEBRUARY 1998
192
K. D. PLANCHER, J. R. STEADMAN, K. K. BRIGGS, AND K. S. HUTTON TABLE IV RESULTS OF TESTING WITH THE KT-1000 ARTHROMETER AT MAXIMUM MANUAL PRESSURE*
Side-to-Side Difference 7.5 mm
Before Reconstruction (No. of Knees) 12 17 25 19
(16%) (23%) (34%) (26%)
After Reconstruction (No. of Knees) 50 22 2 1
(67%) (29%) (3%) (1%)
*Seventy-three knees were examined before reconstruction, and seventy-five were examined after it. The mean side-to-side difference (and standard deviation) was 6.4 ± 3.1 millimeters before the reconstruction and 1.4 ± 3.3 millimeters after it. The mean difference between the preoperative and postoperative values was 5.1 millimeters, which was significant (p < 0.01).
ported patellofemoral pain at the time of the latest follow-up; therefore, no relationship was noted between patellofemoral pain and crepitation. Return to Activity and Satisfaction of the Patient
the index operation before 1987, when we changed our technique to use of interference screws. Second-look arthroscopy was performed, for diagnostic and therapeutic purposes, when the hardware was removed. One patient had inflammation of the patellar ligament, which was relieved with fenestration and arthroscopic debridement. Six patients had second-look arthroscopy for evaluation of chondral defects seen at the index procedure or at the time of debridement. Three patients had lysis of adhesions because of a loss of motion of 5 degrees or more. None of the patients who had an additional procedure had any visible injury to the graft used to reconstruct the anterior cruciate ligament. The patients who had not had a subsequent operation had significantly more improvement in the score on the International Knee Ligament Standard Evaluation Form (p < 0.01). Survivorship Analysis Survivorship curves27, with survival defined as no additional operation on the knee, were calculated for
Bicycling was resumed at a mean of four months; jogging, at a mean of nine months; skiing, at a mean of ten months; and tennis, at a mean of twelve months. Six patients discontinued jogging after the reconstruction or a subsequent operation. All patients were satisfied with the result of the reconstruction and said that they would recommend the procedure to a patient in a similar age-group.
too
60 40
Complications There were no infections in any of our patients. Five patients reinjured the knee, but none sustained a rupture of the reconstructed anterior cruciate ligament. All five patients had an additional procedure for treatment of the reinjury. The first patient slipped and fell on a wet surface two weeks postoperatively, sustaining a rupture of the patellar ligament, which was subsequently repaired. Three years previously, she had had a reconstruction of the anterior cruciate ligament in the contralateral knee, which was not affected by the fall. The second patient fell directly on the knee ten months after the operation and sustained a patellar fracture; the knee was successfully repaired without additional sequelae. The third patient fell seventeen months after the operation and sustained a chondral injury, necessitating arthroscopy, debridement, and chondroplasty. The fourth patient fell during a sports activity two years postoperatively and had recurring effusions. The knee was treated with arthroscopic irrigation and debridement of an area of particulate synovitis. The fifth patient fell while skiing three years after the reconstruction and sustained a meniscal tear, which was debrided arthroscopically. A total of fourteen other patients needed an additional procedure. Four of these patients had removal of hardware that was causing pain. All four had had
^
go
20
0
12
24
36 48 60 72 84 Postoperative Follow-up (months) FIG.
96
108
120
7-A
Figs. 7-A and 7-B: Non-parametric Kaplan-Meier survivorship curves, with survival defined as the absence of a subsequent operation. (No knee had a subsequent operation because of abnormalities of the involved anterior cruciate ligament.) Fig. 7-A: Survivorship curve for all knees that had not had a reinjury. 100
*
80
i" |
40 20
0
12
24
36 48 60 72 84 96 Postoperative Follow-up (months)
108
120
FIG. 7-B Survivorship curve for all knees, including those that had a reinjury.
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the knees that had not had a reinjury (Fig. 7-A) and for all knees, including those that had had a reinjury (Fig. 7-B). Eight years postoperatively, more than 80 per cent of the knees that had not had a reinjury had not needed a subsequent operation. All variables that were associated with, or predictive of, the outcome were incorporated individually in proportional-hazards regression models. With the numbers available for study, we could not detect a significant influence of gender, age, the interval between the injury and the procedure, The Hospital for Special Surgery score23, the Lysholm and Gillquist score30, the results of the Lachman and pivotshift tests, or a previous procedure. Discussion Several studies have demonstrated that reconstruction of a ruptured anterior cruciate ligament is more successful than rehabilitation and use of a brace for young, active patients1'78'11162234'35. Operative intervention has become the standard of treatment for this agegroup. However, reconstruction of the anterior cruciate ligament in patients between the ages of forty and sixty years remains controversial despite the lack of an association between age at the time of reconstruction and decreased postoperative function78. The reason for this ongoing controversy may be that no report, to our knowledge, has specifically documented the outcome of reconstruction of the anterior cruciate ligament in this age-group810. Each patient in our study was carefully evaluated as a candidate for the operation. We have found that middle-aged patients who are highly motivated, are athletically inclined, and desire to return to their previous level of activity can be managed successfully with operative intervention. Our follow-up rate of 96 per cent (seventy-five of seventy-eight knees) exceeded that of most other published studies7'81518'20'22'24'3233'36; of the three knees that were excluded, two had a chronic injury and one had an acute injury of the anterior cruciate ligament. The follow-up was free from surgeon bias, as no final examination was performed by the senior one of us, who performed the operation. All of the patients had been dissatisfied with the performance of the knee after non-operative treatment. In two recent studies, eight (15 per cent) of fiftyfive patients and five (17 per cent) of thirty patients in this age-group were also dissatisfied with non-operative treatment of a rupture of the anterior cruciate ligament810. The rate of dissatisfaction appears to increase with an extended duration of follow-up. In studies of younger patients who had been managed nonoperatively, the rate of poor functional results increased as the interval between the injury and the follow-up examination increased2-6-22'26'35'42. We believe that the rates of dissatisfaction reported after non-operative treatment may represent underestimates of the number of VOL. 80-A, NO. 2, FEBRUARY 1998
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patients who eventually will be unhappy with the function of the knee. An operation had been performed on thirty-four (45 per cent) of the seventy-five knees in our study before the index procedure; however, no knee had had an earlier reconstruction of the anterior cruciate ligament. In a comparably sized group of younger patients, thirty-five (51 per cent) of sixty-eight knees had had a previous operation before the reconstruction of the anterior cruciate ligament7. Skiing was the sport most often responsible for the rupture of the anterior cruciate ligament in our patients. Similarly, skiing caused the injury in twenty-six (50 per cent) of fifty-two middle-aged patients who had been managed non-operatively by Ciccotti et al.10. Conversely, many authors have found that young athletes most frequently sustain a tear of the anterior cruciate ligament while playing football or basketball61634-3540. We agree with the speculation that this age-related disparity with regard to the mechanism of injury results from a shift from team-oriented, organized sports to individual, casual sports as people mature and leave the academic environment10. Evaluation was performed with use of three separate scoring systems. The scale of Lysholm and Gillquist30 was designed specifically for evaluation after operative procedures involving knee ligaments. This scoring system gives an accurate indication of function, with a high number of points assigned to the category of instability, or giving-way30. The mean Lysholm and Gillquist score for our patients increased from 63 points preoperatively to 94 points postoperatively. This finding indicates nearly normal function of the knee and compares favorably with mean scores of 90 and 92 points in younger patients who had an operatively treated tear of the anterior cruciate ligament1. The scores in the current study were markedly higher than those reported after non-operative treatment of a tear of the anterior cruciate ligament in series ranging from thirty to seventy-two patients (mean score, 84 to 86 points for young patients and 82 points for middle-aged patients)110,37'40. The scoring system of The Hospital for Special Surgery23 has been used after reconstruction of the anterior cruciate ligament as well as after non-operative treatment of a rupture of the ligament in several studies78. This rating scale designates more points for pain and range of motion than for instability. The mean preoperative Hospital for Special Surgery score in the present study was 69 points; the score improved to a mean of 92 points after reconstruction of the anterior cruciate ligament. Buss et al.7, in a study of similar size involving patients who were substantially younger (mean age, twenty-four years) than our patients, reported mean Hospital for Special Surgery scores of 40 points preoperatively and 88 points postoperatively. In another study, of non-operative management of patients who were more than thirty years old or who had a limited level
194
K. D. PLANCHER, J. R. STEADMAN, K. K. BRIGGS, AND K. S. HUTTON
of activity, Buss et al.8 reported a mean Hospital for Special Surgery score of 71 points at the time of the latest follow-up; this score is lower than that in the current study. These data indicate that the functional outcome after reconstruction of the anterior cruciate ligament in middle-aged patients is at least as good as that in younger patients7 and is better than that in middleaged patients who are managed non-operatively8. Use of the International Knee Ligament Standard Evaluation Form revealed an overall improvement in the knee scores in our patients. The results of the preoperative Lachman and pivot-shift tests were inversely correlated with the change between the preoperative and postoperative International Knee Ligament Standard Evaluation Form scores: greater changes in the scores were associated with lower values on the tests. This indicates that the preoperative scores on the International Knee Ligament Standard Evaluation Form were more influenced by the patient's assessment and the symptoms than by the examination of the ligament. The Lachman test has been proved to be the most accurate test for the assessment of laxity of the anterior cruciate ligament25. At the time of follow-up, seventyone (95 per cent) of the seventy-five knees had a value of 1+ or less on the Lachman test. These results compare favorably with the findings in a study of younger patients7, in which sixty (88 per cent) of sixty-eight knees had a postoperative value of 1+ or less. Conversely, twenty-nine (97 per cent) of thirty patients who had been managed non-operatively between the ages of forty and sixty years had a Lachman value of 2+ or 3+, indicating residual instability10. As expected, reconstruction of the anterior cruciate ligament resulted in substantially less laxity of the knee in our patients than rehabilitation or use of a brace alone would have810. We believe that this stability contributed to the overall success of the reconstruction. The pivot-shift test has also been used as a clinical indicator of a tear of the anterior cruciate ligament4•". Our patients had a marked reduction in the degree of pivot shift after the reconstruction. Seventy knees (93 per cent) had a value of 0 or 1+, and the remainder had a value of 2+, at the latest follow-up examination. Similar results have been noted in younger patients after reconstruction of the anterior cruciate ligament7. In contrast, twenty (67 per cent) of thirty older patients who had been managed non-operatively had a pivot-shift value of 2+ or 3+10. Although the pivot-shift test is not as accurate as the Lachman test for the assessment of laxity of the anterior cruciate ligament, our patients nevertheless had marked objective improvement in stability of the knee. The preoperative Lachman scores were positively correlated with the preoperative pivot-shift values as well as with the differences between the values on the injured and uninjured sides as measured with the KT-1000 arthrometer at maximum manual pressure. Arthrometric testing has been used to discriminate
between abnormal and normal knees and has been found to be both highly sensitive and specific51213. In several studies that included 120 to 338 normal subjects, 99 per cent had a side-to-side difference of less than three millimeters5'213. In the current study, the mean postoperative side-to-side variance was 1.4 + 3.3 millimeters; it was less than three millimeters in 67 per cent of the knees. Neither the follow-up examination nor the questionnaires revealed a discrete, identifiable cause for the laxity in our patient in whom postoperative arthrometric testing demonstrated a side-to-side difference of five millimeters compared with ten millimeters preoperatively. The patient who had a decrease from 9.5 to nine millimeters had the reconstruction while we were still using the technique of open arthrotomy with an iliotibial-band tenodesis. At this writing, he was still jogging without any symptoms, including giving-way of the knee. The patient who had no change in a 7.5-millimeter side-to-side difference had waited 11.5 years for the reconstruction because of a medical condition. He already had grade-IV changes38 in the medial compartment of the knee at the time of the operation. The bone was soft where the tibial tunnel was placed, necessitating fixation of the graft over a screw and washer. He had limited all athletic activity preoperatively, but he was able to return to golfing, bicycling, and skiing within one year after the operation. The patient who had an increase in the side-to-side difference from 2.5 to 6.5 millimeters had gained weight after the procedure and had hypothyroidism. She stated that the knee had functioned perfectly until the hardware had been removed by another surgeon. She had waited four years before having the reconstruction, which was performed with an open-arthrotomy technique; the rating of C according to the International Knee Ligament Standard Evaluation Form did not improve after the procedure. Despite the values for these four patients, the overall results as measured with the KT-1000 device were comparable with those that have been reported for younger patients who had reconstruction of the anterior cruciate ligament31. Comparison of our data with those obtained in a study of patients who had been managed non-operatively between the ages of forty and sixty years revealed considerable disparity; in that study, the mean side-to-side difference on arthrometric testing at maximum manual pressure was six millimeters10. Similarly high values were found after non-operative treatment of a tear of the anterior cruciate ligament in patients who were more than thirty years old or who led a sedentary lifestyle8. None of our patients had a loss of extension of more than 8 degrees. Similar results were reported by Buss et al.7 after reconstruction of the anterior cruciate ligament in young patients. The potential for arthrofibrosis, defined by many as a 10-degree loss of motion in the involved knee postoperatively43, is a real concern for a THE JOURNAL OF BONE AND JOINT SURGERY
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patient of any age who has a reconstruction of the anterior cruciate ligament. Postoperative restriction in the range of motion has been a concern of many surgeons who perform reconstruction of the anterior cruciate ligament in older patients. This finding was not noted in any of our patients at the latest follow-up evaluation. Although we performed an extra-articular iliotibialband tenodesis routinely in our patients before 1987 and subsequently in selected patients, we discontinued its routine use in mid-1990. We believe that, although this technique is not harmful29, it does not provide any additional benefit for patients having an intra-articular reconstruction. The eighteen knees that had an iliotibialband tenodesis and the fifty-seven that had only an intra-articular reconstruction were not found to differ with respect to the clinical results, the values obtained with use of the KT-1000 arthrometer postoperatively, the range of motion, or the presence of arthrofibrosis. All seventy-two of our patients were satisfied with the operative result. This finding is supported by a comparable rate of satisfaction (sixty-six [97 per cent] of sixty-eight) in a group of younger patients who had been operated on by Buss et al.7. Lower rates of satisfaction have been reported after non-operative treatment in middle-aged patients (twenty-five [83 per cent] of thirty)10 and in patients who were sedentary or were more than thirty-years old (forty-seven [85 per cent] of fifty-five)8. Giving-way has been reported previously in association with a lower knee-rating score81". Our patients reported no giving-way postoperatively. Other authors have reported rates ranging from one (1 per cent) of sixty-eight young, athletic patients who had a reconstruction of the anterior cruciate ligament7 to thirty-four (85 per cent) of forty young, active patients who had been managed non-operatively22 to thirty-two (58 per cent) of fifty-five older patients who had a decreased level of activity and had been managed non-operatively8. These patients may have had a lifestyle similar to that of our patients, who wanted to continue high-level participation in athletic activities after the injury without any modifications. We believe that giving-way should be a relative indication for reconstruction of the anterior cruciate ligament in any age-group. Postoperatively, most of our patients were able to participate in sports activity comfortably. After fiftyseven (76 per cent) of the seventy-five index procedures, the patient was able to return to the preinjury level of sports activity; after fifteen (20 per cent), it was necessary for the patient to modify the level of activity; and after three (4 per cent), the patient no longer engaged in athletic activity because of fear of reinjury. Buss et al.7 found that forty-five (68 per cent) of sixty-six patients who had had reconstruction of the anterior cruciate ligament returned to their preinjury level of participation in sports. The reason most frequently given by the remaining twenty-one patients (32 per cent) for a deVOL. 80-A, NO. 2, FEBRUARY 1998
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crease in activity was a fear of reinjury or an alteration in lifestyle7. Edwards et al.14, in 1991, reported that patients who had been managed for an injury of the anterior cruciate ligament when they were more than thirty years old had a substantially higher rate of return to full, unrestricted, active military service than did those who had been managed for such an injury when they were less than thirty years old. Conversely, in series ranging from thirty to seventy-nine patients who had been managed without a reconstruction of the anterior cruciate ligament681022,14 to 49 per cent returned to the previous level of activity. Edwards et al. believed that patients between the ages of forty and sixty years may have a more successful outcome after reconstruction of the anterior cruciate ligament than younger patients. Older patients may have a greater ability to participate in rehabilitation because of increased financial security. Edwards et al. also thought that compliance with the rehabilitation program may increase with maturity. A successful outcome also may be attained more easily in the forty to sixty-year-old age-group because the preinjury and postinjury sport or occupation of these patients may be less demanding on the knee than that of younger patients14. In the current study, five (7 per cent) of the seventyfive knees sustained a reinjury after the patient returned to activity. This rate is in contrast with that of eleven (37 per cent) of thirty in a group of middle-aged patients who had been managed non-operatively10. In that study, in which the mean duration of follow-up was seven years, only one-third of the patients sustained the second injury within one year after the initial injury and the rate of reinjury was not altered by use of a brace10. A study of ninety-eight younger patients who had been managed without reconstruction of the anterior cruciate ligament documented reinjury in thirty-four (35 per cent) within a mean of fifty months after the initial injury"1. In another study, a younger group of patients (mean age, twenty-six years) who were managed nonoperatively had a similar rate of reinjury (twenty-nine [37 per cent] of seventy-nine)6. Seventeen of these patients had a single reinjury, and twelve had multiple reinjuries. That report also noted poorer results after non-operative treatment as the interval after the initial injury increased. Thirteen (27 per cent) of forty-nine patients who were followed for three to four years had a poor result, whereas fifteen (50 per cent) of thirty patients who were followed for four to eight and onehalf years had such a result6. Other authors have come to similar conclusions with regard to reinjury and outcome215263442. Bonamo et al.6 found reoperation to be a poor prognostic indicator, with nine of twelve patients who had a second arthroscopy eventually having a poor result. The mean age of our patients who had a subsequent procedure was identical to that for the entire
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K. D. P L A N C H E R , J. R. STEADMAN, K. K. BRIGGS, A N D K. S. HUTTON
study group. With one exception, all patients in this subgroup had improvement from a grade of D or C to a grade of B on the International Knee Ligament Standard Evaluation Form. Most of these patients had debridement for chondral defects of the condyles, after which they were able to return to their preinjury sport, Survivorship analysis suggested that 20 per cent of patients who are managed with reconstruction of the anterior cruciate ligament between the ages of forty and sixty years may need a subsequent procedure. If a patient has no problem with the knee within twentyseven months after reconstruction of the anterior cruciate ligament, an excellent outcome can almost always be expected. The mean interval until our patients were able to return to bicycling was four months, that for jogging was nine months, that for skiing was ten months, and that for tennis was twelve months. All patients returned to bicycling, fifty-nine (86 per cent) of the sixty-nine who had jogged previously returned to jogging, sixtyone (91 per Cent) Of the SixtV-SeVen Who had Skied prev
r
.
.
.
,
/ n
'T.
VIOUSly returned tO Skiing, and forty (80 per Cent) Of the
fifty who had played tennis previously returned to playing that game. In conclusion, all of our patients had a satisfactory outcome after reconstruction of the anterior cruciate ligament, and none reported giving-way of the involved knee. The range of active and passive motion was excellent, with no evidence of arthrofibrosis. The rates of reinjury were substantially lower than those reported in studies of similar and younger patients who were managed non-operatively6'71016. The higher rate of poor results seen in association with an increased interval since the injury, repetitive injury, and repeat arthroscopy should be discussed with patients as risks of nonoperative treatment of a tear of the anterior cruciate ligament. When strict criteria for patient selection are followed, a mature athlete who sustains a tear of the anterior cruciate ligament will have a lower risk of reinjury and a very high likelihood of a satisfactory outcome after operative intervention, NoTE: T h e a
"lh°rs thank Bernard Bach, M.D.. Terry Orr. M.D., Arthur Boland, M.D.,
Kevin Stone, M.D., Ken Taylor, M.D., Jeanne Schulteis, B.S., and Cristal Adams. R.N., for theirassistanccinthissludy.SpecialthankstoCarolHowardforpreparationofthismanuscripl.
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21. Harner, C. D.; Irrgang, J. J.; Paul, J.; Dearwater, S.; and Fu, F. H.: Loss of motion after anterior cruciate ligament reconstruction. Am. J. Sports Med., 20: 499-506,1992. 22. Hawkins, R. J.; Misamore, G. W.; and Merritt, T. R.: Followup of the acute nonoperated isolated anterior cruciate ligament tear. Am../. Sports Med., 14:205-210,1986. 23. Insall, J. N.; Ranawat, C. S.; Aglietti, P.; and Shine, J.: A comparison of four models of total knee-replacement prostheses. / Bone and Joint Surg., 58-A: 754-765, Sept. 1976. 24. Jokl, P.; Kaplan, N.; Stovell, P.; and Keggi, K.: Non-operative treatment of severe injuries to the medial and anterior cruciate ligaments of the knee. /. Bone and Joint Surg., 66-A: 741-744, June 1984. 25. Jonsson, T.; Althoff, B.; Peterson, L.; and Renstrom, P.: Clinical diagnosis of ruptures of the anterior cruciate ligament: a comparative study of the Lachman test and the anterior drawer sign. Am. J. Sports Med., 10:100-102,1982. 26. Kannus. P., and Jarvinen, M.: Conservatively treated tears of the anterior cruciate ligament. Long-term results. J. Bone and Joint Surg., 69-A: 1007-1012, Sept. 1987. 27. Kaplan, E. L., and Meier, P.: Nonparametric estimation from incomplete observations. J. Am. Statist. Assn., 53:457-481,1958. 28. Kurosaka, M.; Yoshiya, S.; and Andrish, J. T.: A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am. J. Sports Med., 15: 225-229,1987. 29. Larson, R. L., and Taillon, M.: Anterior cruciate ligament insufficiency: principles of treatment. J. Am. Acad. Orthop. Surgeons, 2: 2635,1994. 30. Lysholm, J., and Gillquist, J.: Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am. J. Sports Med., 10:150-154,1982. 31. McCarroll, J. R.; Shelbourne, K. D.; and Rettig, A. C: Anterior cruciate ligament reconstruction in the competitive athlete. Orthop. Trans., 13: 617-618,1989. 32. McDaniel, W. J., Jr., and Dameron, T. B., Jr.: Untreated ruptures of the anterior cruciate ligament. A follow-up study../. Bone and Joint Surg., 62-A: 696-705, July 1980. 33. McDaniel, W. J., Jr., and Dameron, T. B., Jr.: The untreated anterior cruciate ligament rupture. Clin. Orthop., 172:158-163,1983. 34. Noyes, F. R.; Matthews, D. S.; Mooar, P. A.; and Grood, E. S.: The symptomatic anterior cruciate-deficient knee. Part II: The results of rehabilitation, activity modification, and counseling on functional disability. J. Bone and Joint Surg., 65-A: 163-174, Feb. 1983. 35. Noyes, F. R.; Mooar, P. A.; Matthews, D. S.; and Butler, D. L.: The symptomatic anterior cruciate-deficient knee. Part I: The long-term functional disability in athletically active individuals. /. Bone and Joint Surg., 65-A: 154-162, Feb. 1983. 36. Odensten, M.; Lysholm, J.; and Gillquist, J.: The course of partial anterior cruciate ligament ruptures. Am. J. Sports Med., 13: 183186,1985. 37. Odensten, M.; Hamberg, P.; Nordin, M.; Lysholm, J.; and Gillquist, J.: Surgical or conservative treatment of the acutely torn anterior cruciate ligament. A randomized study with short-term follow-up observations. Clin. Orthop., 198: 87-93,1985. 38. Outerbridge, R. E.: The etiology of chondromalacia patellae. / Bone and Joint Surg., 43-B(4): 752-757,1961. 39. Paschal, S. O.; Seemann, M. D.; Ashman, R. B.; and Allard, R. N.: A biomechanical comparison of interference versus post-fixation of bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction. Orthop. Trans., 16:80,1992. 40. Pattee, G. A.; Fox, J. M.; Del Pizzo, W.; and Friedman, M. J.: Four to ten year followup of unreconstructed anterior cruciate ligament tears. Am. J. Sports Med., 17: 430-435,1989. 41. Sachs, R. A.; Daniel, D. M.; Stone, M. L.; and Garfein, R. F.: Patellofemoral problems after anterior cruciate ligament reconstruction. Am. J. Sports Med., 17: 760-765,1989. 42. Satku, K.; Kumar, V. P.; and Ngoi, S. S.: Anterior cruciate ligament injuries. To counsel or to operate? J. Bone and Joint Surg., 68-B(3): 458-461,1986. 43. Shelbourne, K. D.; Patel, D. V.; and Martini, D. J.: Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction. Am. J. Sports Med., 24:857-862,1996. 44. Steadman, J. R., and Seemann, M. D.: ACL injuries in the elite skier. In The Crucial Ligaments. Diagnosis and Treatment of Ligamentous Injuries about the Knee, edited by J. A. Feagin, Jr. Ed. 2, pp. 759-772. New York, Churchill Livingstone, 1994. 45. Strum, G. M.; Friedman, M. J.; Fox, J. M.; Ferkel, R. D.; Dorey, F. H.; Del Pizzo, W.; and Snyder, S. J.: Acute anterior cruciate ligament reconstruction. Analysis of complications. Clin. Orthop., 253:184-189,1990. 46. Zarins, B., and Adams, M.: Knee injuries in sports. New England J. Med., 318:950-961,1988.
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