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Prospective clinical comparisons of semitendinosus versus semitendinosus and gracilis tendon autografts for anatomic double-bundle anterior cruciate ligament reconstruction
J Orthop Sci DOI 10.1007/s00776-013-0427-9
ORIGINAL ARTICLE
Prospective clinical comparisons of semitendinosus versus semitendinosus and gracilis tendon autografts for anatomic double-bundle anterior cruciate ligament reconstruction Yusuke Inagaki • Eiji Kondo • Nobuto Kitamura • Jun Onodera • Tomonori Yagi • Yasuhito Tanaka • Kazunori Yasuda
Received: 21 February 2013 / Accepted: 1 June 2013 Ó The Japanese Orthopaedic Association 2013
Abstract Background The data available from the previously reported clinical studies remains insufficient concerning the hamstring graft preparation in double-bundle anterior cruciate ligament (ACL) reconstruction. Objective To test the hypothesis that there are no significant differences between the semitendinosus tendon alone and the semitendinosus and gracilis tendon graft fashioning techniques concerning knee stability and clinical outcome after anatomic double-bundle ACL reconstruction. Methods A prospective study was performed on 120 patients who underwent anatomic double-bundle ACL reconstruction according to the graft fashioning technique. The authors developed the protocol to use hamstring tendon autografts. When the harvested doubled semitendinosus tendon is thicker than 6 mm, each half of the semitendinosus tendon is doubled and used for the anteromedial (AM) and posterolateral (PL) bundle grafts (Group I). On the other hand, when the harvested semitendinosus This paper was presented at the 8th Biennial International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Congress, 15–19 May 2011, Rio de Janeiro, Brazil. Y. Inagaki E. Kondo (&) N. Kitamura J. Onodera K. Yasuda Department of Sports Medicine and Joint Surgery, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan e-mail: [email protected] Y. Inagaki Y. Tanaka Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan T. Yagi Department of Orthopedic Surgery, Yamanote-dori Yagi Hospital, Sapporo, Hokkaido, Japan
tendon is under 6 mm in thickness, the gracilis tendon is harvested additionally. The distal half of the semitendinosus and gracilis tendons are doubled and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon is doubled and used for the PL bundle grafts (Group II). Sixty-one patients were included in Group I, and 59 patients in Group II. The two groups were compared concerning knee stability and clinical outcome 2 years after surgery. Results The postoperative side-to-side anterior laxity averaged 1.3 mm in both groups, showing no statistical difference. There were also no significant differences between the two groups concerning the peak isokinetic torque of the quadriceps and the hamstrings, the Lysholm knee score, and the International Knee Documentation Committee evaluation. Conclusion There were no significant differences between the two graft fashioning techniques after anatomic double-bundle ACL reconstruction concerning knee stability and postoperative outcome. The present study provided orthopedic surgeons with important information on double-bundle ACL reconstruction with hamstring tendons. Level of evidence Level II; prospective comparative study.
Introduction The normal anterior cruciate ligament (ACL) consists of the anteromedial (AM) and posterolateral (PL) bundles, which have different functions [1, 2]. The idea of reconstructing both bundles was proposed in the 1980s [3]. In the early 2000s, since Yasuda et al. [4] reported a new concept of anatomic reconstruction of the AM and PL bundles of the ACL with 2-year clinical results superior to conventional
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single-bundle ACL reconstruction, a number of anatomic, biomechanical, and clinical studies on the anatomic doublebundle reconstruction procedures have been conducted in the field of ACL reconstruction, and several clinical trials have found that postoperative knee stability is superior in the anatomic double-bundle reconstruction compared with conventional single-bundle reconstruction [5–13]. The essence of ACL reconstruction is grafting tendon bundles across the knee joint. Therefore, graft selection, preparation, and fixation are critical factors to ensure ACL reconstruction leads to clinical success [14]. However, it has been well established that the weak points of the hamstring tendon graft fixed with sutures to bone are (1) low stiffness of the graft-suture-bone complex, (2) rapid relaxation of the graft tension after surgery, and (3) difficulty in tension control during graft fixation [15, 16]. Therefore, the authors have developed hamstring tendon ‘hybrid’ autografts which consist of hamstring tendon connected in series with commercially available polyester tape (Leeds-Keio Artificial Ligament, Neo Ligament, Leeds, England, United Kingdom) [10, 15, 16]. The hybrid graft was used to address the above described weak points based on biomechanical studies [17–19]. In anatomic double-bundle ACL reconstruction, the authors developed the protocol described below to fully utilize the limited amount of hamstring tendon. Concerning the graft preparation in double-bundle ACL reconstruction, a few clinical comparisons between different fashioning techniques have been reported [20, 21]. On the basis of clinical results [8, 9, 13], the authors hypothesized that there are no significant differences between the semitendinosus tendon alone and semitendinosus and gracilis tendon graft fashioning methods concerning knee stability and clinical outcome after anatomic double-bundle ACL reconstruction. The purpose of this study was to test this hypothesis.
routinely performed computed digital radiographs and MRI scans, and the findings at surgery. Patients with a combined ligament injury in the posterior cruciate ligament, the lateral collateral ligament, the PL corner structures of the knee, and medial collateral ligament (grade 3) were excluded from this study. In addition, patients with any previous operations for ligament injuries, a concurrent fracture, or severe osteoarthritis were excluded. The time from onset of injury to surgery was 1 month or more. This clinical study design had been accepted by the institutional review board clearance in this hospital before commencement, based on the described study design and informed consent. In 2004, 2005 and 2006, 55, 42, and 46 patients, respectively, were enrolled in this study. Patients were informed that they were going to be in a study, and that they could choose another graft type if they did not wish to participate in this study. Other surgical options in this hospital included single-bundle reconstruction with hamstring tendon autografts, or a bone-patella tendon-bone autograft. The patients who did not wish to take part in this study were not enrolled. Two years after surgery, each patient was examined with the standard clinical evaluation methods. One hundred and twenty patients (83.9 %) underwent the same followup examinations, while 23 patients were lost (Fig. 1); 16 patients were excluded from the evaluation because there were no muscle torque data taken at the final follow-up. Two patients were excluded for contralateral ACL injury and ipsilateral revision ACL surgery, respectively. Finally, three patients did not attend the regular follow-up after ACL reconstruction up to 2 years postoperatively. There were 68 men and 52 women with an average age of 27 years at the time of surgery. In Group I, 61 patients underwent anatomic double-bundle ACL reconstruction using the semitendinosus tendon alone. In Group II, 59 patients underwent anatomic double-bundle ACL
Materials and methods
143 patients 2004: 55 patients 2005: 42 patients 2006: 46 patients
Study design A prospective, comparative, cohort study was conducted in 143 patients who underwent anatomic double-bundle ACL reconstruction using hamstring tendon autografts in one of the author’s affiliate hospitals between 2004 and 2006. Based on the graft fashioning protocol described below, the authors performed anatomic double-bundle reconstruction using semitendinosus tendon autograft or semitendinosus and gracilis tendon autografts for all patients. Each patient showed an ACL deficiency in the unilateral knee at the time of surgery. The diagnosis of injured ligaments was made based on a detailed history of the knee injury, physical examinations on pathologic status and abnormal laxity,
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Group I
Group II
75 patients
> 2-yr f/u
61 patients
68 patients
Loss of f/u
23 patients
> 2-yr f/u
59 patients
Fig. 1 Flowchart demonstrating patient movement through the study
Hamstring graft in DB ACL reconstruction Table 1 Comparison of background factors of patients between Groups I and II Group I (N = 61)
Group II (N = 59)
P value 0.320
Age (years)
28.2 ± 11.9
26.2 ± 10.3
Male/female (patients)
35/26
33/26
0.873
Height (cm) Weight (kg)
166.4 ± 7.9 62.5 ± 9.3
166.3 ± 8.4 65.6 ± 10.7
0.954 0.0954
Interval between injury and operation (months)
23.6 ± 50.4
16.1 ± 46.3
0.394
Meniscal injury (patients)a
9:4
12:5
0.343
Values are expressed as mean ± SD a
The number of patients with partial resection versus that with meniscus repair
Fig. 2 The hamstring tendon hybrid autografts for anatomic doublebundle anterior cruciate ligament reconstruction. The lengths of autografts were 60–70 and 50–60 mm for AM and PL bundles, respectively. AM anteromedial, PL posterolateral
Graft fashioning technique reconstruction using the semitendinosus and gracilis tendons. There were no significant differences between the two groups concerning age, gender, height, weight, and the time to surgery (Table 1). One senior orthopedic surgeon (K.Y.) performed all operations using the same procedure for each group. At the time of reconstruction, the medial or lateral meniscus was partially resected in 21 patients, and repaired in nine patients (Table 1). No treatment was administered for softening or fissuring of the articular cartilage. In each group, an approximately 3-cm-long incision was made in the antero-medial portion of the proximal tibia, and the hamstring tendon was harvested using a tendon stripper. Concerning the graft selection for each patient, first, a surgeon harvested the semitendinosus tendon. When the harvested doubled distal portion of the semitendinosus tendon was thicker than 6 mm, the semitendinosus tendon was used for the AM and PL bundle graft. On the other hand, when the harvested doubled distal portion of the semitendinosus tendon was under 6 mm in thickness, the gracilis tendon was harvested additionally. The length of the semitendinosus tendon or/and gracilis tendon was measured using a linear scale. The distance from the tibial insertion of the tendon to its tendinous termination into muscle was defined as the length of the tendon [22]. The cross-sectional area of the tendon portion was measured with a cylindrical gauge (Sizing system, Acufex, Smith & Nephew Endoscopy, Andover, Massachusetts). After the harvested tendon was passed through each stainless tube, the greatest diameter of the gauge was defined as the diameter of the tendon. Each reconstruction procedure was performed using the arthroscopically assisted 1-incision (transtibial tunnel) technique. Each graft was secured with EndoButtons-CL (Smith & Nephew Endoscopy) on the femur and with two staples (Meira, Nagoya, Japan) on the tibia. All patients underwent postoperative management with the same rehabilitation protocol [9, 23].
In Group I, when the harvested doubled semitendinosus tendon was thicker than 6 mm, the semitendinosus tendon was cut into two parts. The distal half of the semitendinosus tendon was doubled (two strands) with side-by-side sutures and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon was also doubled (two strands) with side-by-side sutures and used for the PL bundle graft (Fig. 2). The lengths of the autografts were 60–70 and 50–60 mm for the AM and PL bundle grafts, respectively. The autografts were connected in series with 10-mm-width polyester tape (Leeds-Keio Artificial Ligament, Neo Ligament) at the tibial side and attached to the Endobutton-CL (Smith & Nephew Endoscopy) (Fig. 2). The size of the Endobutton-CL was adjusted so that an autogenous tendon portion of 15–20 mm was located in the femoral and tibial tunnels. In Group II, when the harvested semitendinosus tendon was under 6 mm in thickness, the gracilis tendon was harvested additionally. The distal half of the semitendinosus and the gracilis tendons were doubled (four strands) with side-by-side sutures and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon was doubled (two strands) with side-by-side sutures and used for the PL bundle grafts. However, when the doubled proximal half of the semitendinosus tendon was under 5 mm in thickness, the proximal half of the gracilis tendon was added additionally. Then, three or four strand semitendinosus and gracilis tendons were used for the PL bundle grafts. After that, the two hamstring hybrid autografts were fashioned in the same manner as in Group I. Anatomic double-bundle ACL reconstruction procedure The details of this procedure have been previously described in the literature [4, 13]. Briefly, a tibial tunnel for the PL bundle was created. To insert a guidewire, a hole-in-
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one guide (Wire-navigator, Smith & Nephew Endoscopy, Tokyo, Japan) was used. The tibial indicator of the Navi-tip was placed at the center of the PL bundle footprint on the tibia. Then, keeping the tibial indicator at this point, the femoral indicator was aimed at the center of the PL bundle attachment on the femur. A guidewire was drilled through the sleeve in the tibia. Then, a guidewire for AM bundle reconstruction was inserted in the same manner. Using a wire-navigator, the femoral indicator was aimed at the center of the AM bundle attachment on the femur. The two tibial tunnels were made with a cannulated drill corresponding to the measured diameter of the prepared substitute. To create two femoral tunnels for the AM and PL bundles in the lateral condyle, first, a guidewire was drilled at the center of the femoral attachment of the AM bundle through the AM tibial tunnel by use of an offset guide (transtibial femoral ACL Drill Guide, Arthrex, Naples, FL, USA). Using the inserted guidewire, a tunnel was made with a 4.5-mm cannulated drill. The length of the tunnel was measured with a scaled probe. Then, the portal for an arthroscope was changed to the medial infrapatellar portal. A guidewire was inserted at the center of the PL bundle attachment on the femur through the PL tibial tunnel. A 4.5-mm-diameter tunnel was drilled, and its length was measured in the same manner. Finally, two sockets were created for the AM and PL bundles, respectively, with cannulated drills, the diameter of which was matched to the two grafts prepared with the technique described above. Finally, the graft for the PL bundle was introduced through the tibial tunnel to the femoral tunnel by use of a passing pin. The EndoButton was flipped on the femoral cortical surface. Then, the graft for the AM bundle was placed in the same manner. For graft fixation, an assistant surgeon simultaneously applied tension of 30 N to each graft using two tensiometers (Meira, Nagoya, Japan) at 10° of knee flexion for 2 minutes. Then, a surgeon simultaneously secured the two tape portions onto the tibia using two spiked staples (Meira) in the turn-buckle fashion. Clinical evaluations Each patient underwent clinical examination 2 years after surgery. The side-to-side anterior laxity was measured with a KT-2000 arthrometer (MEDmetric, San Diego, CA, USA) at 30° of knee flexion under an anterior drawer force of 133 N. A well-trained physical therapist who was blinded to the procedure collected the KT-2000 arthrometer results postoperatively. An experienced orthopedic surgeon (E.K.), who was also blinded to the procedure, performed the pivot-shift test, the results of which were subjectively evaluated by the examiner. In evaluation of the pivot-shift test [4, 9], the indication of ?? was defined when the
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examiner felt a sudden rotational slip movement between the tibia and femur, a so-called jog, during the test for the injured knee. The ?? pivot-shift test result showed an obvious failure of the ACL function. The indication of ? was defined when the examiner felt some difference in the rotational movement during the test between the injured and uninjured knees but did not obviously feel the sudden rotational slip movement. This condition showed some insufficiency of the ACL function but did not show a complete failure of the ACL. As to overall evaluation, the Lysholm knee score (maximum score 100 points) and the International Knee Documentation Committee (IKDC) form were used. Peak isokinetic torque of the quadriceps and the hamstrings was measured at 60 °/s of angular velocity using KIN-COM (Chattecx Corp, Chattanooga, TN, USA) in both knees after surgery. Muscle torque as measured postoperatively in the uninvolved knee was represented as a ratio (percentage) to the uninvolved value. Statistical analysis All data were shown as means with SD. For each parameter, unpaired Student’s t test and Chi-square test were performed between the two groups. When a significant result was obtained, a post hoc test with a Fisher protected least significant difference test was made for multiple comparisons. Correlations between the side-to-side anterior laxity and the tunnel diameter were calculated by use of the Pearson correlation coefficient. A commercially available software program (StatView, SAS Institute, Cary, NC, USA) was used for statistical calculation. The significance level was set at P = 0.05.
Results In Group I, the lengths and the diameters of the semitendinosus tendon averaged 254.4 and 4.7 mm (Table 2), respectively. In Group II, the lengths and the diameters of the semitendinosus tendon averaged 235.2 and 4.4 mm (Table 2), respectively, while those of the gracilis tendon averaged 206.0 and 3.4 mm. The length of the semitendinosus tendons in Group I was significantly longer than those of the semitendinosus tendons (P \ 0.0001) in Group II. The diameter of the semitendinosus tendons in Group I was also significantly thicker than those of the semitendinosus tendons (P \ 0.0001) in Group II. Concerning the diameter of the AM bundle graft, Group II was significantly greater (P \ 0.0001) than Group I (Table 2). Regarding the diameter of the PL bundle graft, there were no significant differences between the two groups. The distribution of the AM and PL bundle graft diameter in Groups I and II are shown in Fig. 3.
Hamstring graft in DB ACL reconstruction
The postoperative side-to-side anterior laxity measured at 30° of knee flexion with the KT-2000 averaged 1.3 mm in both groups, showing no statistical difference. In each group, there was no significant relationship between the femoral and tibial tunnel diameter of the AM and PL grafts and the postoperative side-to-side anterior laxity (correlation coefficients range; r = -0.171 to 0.17, P = 0.1189–0.9613). Regarding the pivot-shift test (Table 3), the Chi-square test Table 2 The lengths and diameters of the semitendinosus and gracilis tendons, and the diameters of the anteromedial and posterolateral tunnels of the femur and tibia in Groups I and II Group I (N = 61)
Group II (N = 59)
P value
Discussion
Semitendinosus tendon Length (mm)
254.4 ± 15.9
235.2 ± 22.9
\0.0001
Diameter (mm)
4.7 ± 0.5
4.4 ± 0.5
\0.0001
Gracilis tendon Length (mm)
Not applicable
Diameter (mm)
206.0 ± 26.0 3.4 ± 0.5
Anteromedial bundle graft Diameter (mm)
6.2 ± 0.5
6.9 ± 0.5
\0.0001
5.9 ± 0.3a
0.639
Posterolateral bundle graft Diameter (mm)
showed no significant difference between the two groups. Concerning the range of knee motion, there was no patient with loss of terminal knee extension in Group I. On the other hand, three patients had loss of knee extension over 5° in Group II. In both groups, there was no patient with loss of terminal knee flexion over 15°. Regarding the ratio of the involved limb to the contralateral limb about the peak isokinetic torque of the quadriceps and the hamstrings, there were no significant differences between the two groups (Table 3). There were also no significant differences between the two groups concerning the Lysholm knee score, and the IKDC evaluation (Table 3).
5.9 ± 0.4
Values are expressed as mean ± SD a
In 19 patients, the semitendinosus and gracilis tendons were used for the PL bundle graft
This study demonstrated that there are no significant differences between the semitendinosus tendon alone and the semitendinosus and gracilis tendon graft fashioning techniques concerning the postoperative side-to-side anterior laxity, the peak muscle torque, the range of knee motion, the Lysholm knee score, and the IKDC evaluation 2 years after anatomic double-bundle ACL reconstruction. The postoperative side-to-side anterior laxity measured with KT-2000 averaged 1.3 mm in both groups. The Lysholm score and the IKDC evaluation achieved good results in both groups compared with the previously reported results after anatomic double-bundle reconstruction [4–6,
Group I (AM bundle graft)
50
40
Patients
Patients
40 30 20
30 20 10
10 0
Group I (PL bundle graft)
50
0 5
5.5
6
6.5
7
7.5
8
5
5.5
Group II (AM bundle graft)
7
7.5
8
7.5
8
Group II (PL bundle graft)
50
40
40
Patients
Patients
6.5
Diameter (mm)
Diameter (mm) 50
6
30 20 10
30 20 10
0
0 5
5.5
6
6.5
7
Diameter (mm)
7.5
8
5
5.5
6
6.5
7
Diameter (mm)
Fig. 3 The distribution of the AM and PL bundle graft diameters in Groups I and II. AM anteromedial, PL posterolateral
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Y. Inagaki et al. Table 3 Comparisons in the clinical outcome between Groups I and II Group I (N = 61)
Group II (N = 59)
P value
1.3 ± 1.4
1.3 ± 1.5
0.825
(-) (?)
48 patients 13 patients
45 patients 14 patients
(??)
0 patient
0 patient
Loss of extension ([5°)
0 patient
3 patients
Loss of flexion ([15°)
Anterior laxitya (mm) Pivot-shift test
0.751
Loss of knee motion
0.0745 0 patient
0 patient
Peak isokinetic torque of the quadricepsb (%)
86.4 ± 15.9
87.6 ± 14.6
0.661
Peak isokinetic torque of the hamstringsb (%) Lysholm knee score (points)
93.3 ± 17.8
92.6 ± 15.1
0.842
97.0 ± 4.6
96.7 ± 5.4
IKDC score
0.775 0.593
A (normal)
46 patients
44 patients
B (nearly normal)
15 patients
14 patients
C (nearly abnormal)
0 patient
1 patient
D (abnormal)
0 patient
0 patient
Values are expressed as mean ± SD a
Difference of anterior knee laxity between treated knee and uninjured knee (mm)
b
Ratio of treated knee to uninjured knee (%)
8–11, 13, 23]. The results indicated that this graft fashioning procedure may be an effective method in restoring knee stability in anatomic double-bundle ACL reconstruction. The reason for the similar results in the two groups is that the difference in tunnel diameter between the two groups was\1 mm, so it may not affect the maturation and the function of the grafts. Recently, Zhao et al. [21] compared the clinical results of a double-bundle ACL reconstruction with four strands versus eight strands of hamstring tendon graft. They reported that a double-bundle ACL reconstruction with eight strands yields significantly better results than a double-bundle ACL reconstruction with four strands, concerning the side-to-side difference in anterior knee laxity, the IKDC subjective result, and the Lysholm score. However, Zhao et al. [21] described that their double-bundle reconstruction was not an anatomic reconstruction. On the tibial side, the inner openings of both bundles were 7-mm anterior to the tip of the tibial spine and located on a medial–lateral line, side by side. In addition, Li [24] pointed out that the diameter of an eight-strand hamstring tendon (mean diameter 8 mm, range 6–11 mm) was significantly greater than that of a native ACL. Therefore, notchplasty was performed in more patients in the eightstrand hamstring tendon group than in the four-strand group. Because of the obviously decreased volume of the knee
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cavity following reconstruction, impingement between the eight-strand hamstring graft and the posterior cruciate ligament or the femoral notch might occur, which could impair the strength and reduce the longevity of the graft, and even the posterior cruciate ligament, because of intermittent shear force following knee motion. In this study, the mean AM bundle diameters were 6.2 and 6.9 mm in Groups I and II, respectively. Therefore, in the author’s double-bundle reconstruction, most patients did not show graft impingement, because the placed AM and PL grafts were relatively thin and anatomically twisted in the intercondylar notch. Therefore, the authors did not perform the notchplasty except in chronic cases. However, the authors found some tendency of a difference in postoperative loss of knee extension between the two procedures. Namely, three patients showed loss of knee extension by 5°–10° in Group II, while there were no patients with loss of knee extension in Group I. From the clinical viewpoint, the loss of knee extension is one of the pathological conditions that should be absolutely avoided after ACL reconstruction [25]. Even though this difference was not statistically significant, the authors believe it was clinically important for avoiding graft impingement. Therefore, surgeons should consider the graft thickness for graft preparation using the semitendinosus and gracilis tendon graft fashioning techniques. Recently, Niki et al. [20] reported the clinical results of anatomic double-bundle ACL reconstruction by use of bone-patellar tendon-bone and gracilis tendon grafts and compared them with the results of double-bundle ACL reconstruction by use of semitendinosus tendon or semitendinosus and gracilis tendon grafts. At 2 years follow-up, there were no significant differences in terms of the Lysholm score, Tegner activity level, and IKDC evaluation among the three groups. In their hamstring double-bundle ACL reconstruction, two double-looped semitendinosus tendons were prepared for both the AM and PL bundle grafts when the semitendinosus tendon was 24 cm or longer. Gracilis tendon was harvested for the PL bundle graft and double looped only when the semitendinosus tendon was \24 cm long. This protocol was different from the authors’ graft preparation protocol. In our protocol, the authors consider that a 6-mm diameter may be the necessary thickness of the AM hamstring graft in ACL reconstruction, based on previous cadaveric studies [26–28]. Although, in general, long hamstring tendons have thick diameters, while short tendons have thin diameters, surgeons should consider not only the graft length but also the graft thickness for graft preparation. There are many reports on the effect of additional gracilis tendon harvesting in single bundle ACL reconstruction [29–34]. Tashiro et al. [34] reported that patients with reconstructed single bundle ACLs with semitendinosus and gracilis tendons showed lower isokinetic and isometric muscle peak torque in the deep knee flexion range
Hamstring graft in DB ACL reconstruction
than those with semitendinosus only. Segawa et al. [33] and Gobbi et al. [31] also reported the weakness of internal rotation muscle strength in those with semitendinosus and gracilis tendons than those with semitendinosus tendon only. On the other hand, Ardern et al. [30] showed no statistical difference concerning the muscle strength between the groups which were grouped in the same manner as this study. Nakamura et al. [32] reported a decrease in maximum standing knee flexion angle of the involved limb compared to the uninvolved limb in patients who underwent ACL reconstruction with semitendinosus and gracilis tendons, compared with those with semitendinosus tendon only. On the contrary, the above mentioned Ardern et al. [30] reported that there was no correlation between the maximum standing knee flexion angle and the isometric muscle torque at 105° of knee flexion, so it should not be used as the clinical parameter of postoperative muscle strength. Therefore, in addition to long-term results, more detailed evaluation on the muscle strength such as the value at deep knee flexion, and the internal muscle torque of knee is needed. There were several limitations to this study. The first limitation is that the patients were not truly randomized because the authors used the originally developed graft fashioning protocol in anatomic double-bundle ACL reconstruction. Although age, gender, height, weight, and the time from injury to surgery were not completely the same between the two groups, there were no statistical differences. The second limitation is that the authors only evaluated the peak isokinetic torque of the quadriceps and the hamstrings at 60 °/s of angular velocity after ACL reconstructions with hamstring tendon graft. The third limitation is that the follow-up period was only 2 years. Therefore, at the present time, the authors cannot speculate as to whether there will be differences between the two different graft fashioning techniques in terms of long-term outcome of knee function and return to sports. The fourth limitation is that the authors did not precisely evaluate the ability of sports performance because, in the short-term results, these parameters are commonly favorable, independent of reconstruction procedures. In the future, the authors should conduct a long-term follow-up study to compare the subjective evaluation and the ability of sports performance between the two groups. However, beyond these limitations, the present study provided orthopedic surgeons with important information on double-bundle ACL reconstruction with hamstring tendons.
Conclusion In this study, the authors did not find any significant differences between the two graft types of hamstring tendon
hybrid autograft (semitendinosus only, or semitendinosus and gracilis tendons) after anatomic double-bundle ACL reconstruction, concerning postoperative side-to-side anterior laxity, peak muscle torque, range of knee motion, Lysholm knee score, or IKDC evaluation 2 years after the operation. Acknowledgments This research was supported in part by Grantsin-Aid for scientific research (21500400) from the Ministry of Education, Science and Culture, Japan. The authors report no conflict of interest.
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ligament: biomedical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am. 1999;81: 549–57. Yasuda K, Tsujino J, Ohkoshi Y, Tanabe Y, Kaneda K. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med. 1995;23:706–14. Yasuda K, Tsujino J, Tanabe Y, Kaneda K. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Autogenous doubled hamstring tendons connected in series with polyester tapes. Am J Sports Med. 1997;25: 99–106. Miyata K, Yasuda K, Kondo E, Nakano H, Kimura S, Hara N. Biomechanical comparison of anterior cruciate ligament: reconstruction procedures with flexor tendon graft. J Orthop Sci. 2000;5:585–92. Numazaki H, Tohyama H, Nakano H, Kikuchi S, Yasuda K. The effect of initial graft tension in anterior cruciate ligament reconstruction on the mechanical behaviors of the femur-grafttibia complex during cyclic loading. Am J Sports Med. 2002;30:800–5. Yamanaka M, Yasuda K, Tohyama H, Nakano H, Wada T. The effect of cyclic displacement on the biomechanical characteristics of anterior cruciate ligament reconstructions. Am J Sports Med. 1999;27:772–7. Niki Y, Matsumoto H, Hakozaki A, Kanagawa H, Toyama Y, Suda Y. Anatomic double-bundle anterior cruciate ligament reconstruction using bone-patellar tendon-bone and gracilis tendon graft: a comparative study with 2-year follow-up results of semitendinosus tendon grafts alone or semitendinosus-gracilis tendon grafts. Arthroscopy. 2011;27:1242–51. Zhao J, He Y, Wang J. Double-bundle anterior cruciate ligament reconstruction: four versus eight strands of hamstring tendon graft. Arthroscopy. 2007;23:766–70. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev. 1991;20:1085–8. Tohyama H, Kondo E, Hayashi R, Kitamura N, Yasuda K. Gender-based differences in outcome after anatomic doublebundle anterior cruciate ligament reconstruction with hamstring tendon autografts. Am J Sports Med. 2011;39:1849–57. Li B. Concerns about double-bundle reconstruction with 8-strand hamstring tendon graft. Arthroscopy. 2008;24:969.
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25. Shelbourne KD, Urch SE, Gray T, Freeman H. Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery. Am J Sports Med. 2012;40:108–13. 26. Takahashi M, Doi M, Abe M, Suzuki D, Nagano A. Anatomical study of the femoral and tibial insertions of the anteromedial and posterolateral bundles of human anterior cruciate ligament. Am J Sports Med. 2006;34:787–92. 27. Mochizuki T, Muneta T, Nagase T, Shirasawa S, Akita K, Sekiya I. Cadaveric knee observation study for describing anatomic femoral placement for two-bundle anterior cruciate ligament reconstruction. Arthroscopy. 2006;22:356–61. 28. Edwards A, Bull AMJ, Amis AA. The attachments of the anteromedial and posterolateral fibre bundles of the anterior cruciate ligament part 2: femoral attachment. Knee Surg Sports Traumatol Arthrosc. 2008;16:29–36. 29. Adachi N, Ochi M, Uchio Y, Sakai Y, Kuriwaka M, Fujihara A. Harvesting hamstring tendons for ACL reconstruction influences postoperative hamstring muscle performance. Arch Orthop Trauma Surg. 2003;123:460–5. 30. Ardern CL, Webster KE, Taylor NF, Feller JA. Hamstring strength recovery after hamstring tendon harvest for anterior cruciate ligament reconstruction: a comparison between graft types. Arthroscopy. 2010;26:462–9. 31. Gobbi A, Domzalski M, Pascual J, Zanazzo M. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy. 2005;21:275–80. 32. Nakamura N, Horibe S, Sasaki S, Kitaguchi T, Tagami M, Mitsuoka T, Toritsuka Y, Hamada M, Shino K. Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons. Arthroscopy. 2002;18:598–602. 33. Segawa H, Omori G, Koga Y, Kameo T, Iida S, Tanaka M. Rotational muscle strength of the limb after anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon. Arthroscopy. 2002;18:177–82. 34. Tashiro T, Kurosawa H, Kawakami A, Hikita A, Fukui N. Influence of medial hamstring tendon harvest on knee flexor strength after anterior cruciate ligament reconstruction, a detailed evaluation with comparison of single- and double-tendon harvest. Am J Sports Med. 2003;31:522–9.
ORIGINAL ARTICLE
Prospective clinical comparisons of semitendinosus versus semitendinosus and gracilis tendon autografts for anatomic double-bundle anterior cruciate ligament reconstruction Yusuke Inagaki • Eiji Kondo • Nobuto Kitamura • Jun Onodera • Tomonori Yagi • Yasuhito Tanaka • Kazunori Yasuda
Received: 21 February 2013 / Accepted: 1 June 2013 Ó The Japanese Orthopaedic Association 2013
Abstract Background The data available from the previously reported clinical studies remains insufficient concerning the hamstring graft preparation in double-bundle anterior cruciate ligament (ACL) reconstruction. Objective To test the hypothesis that there are no significant differences between the semitendinosus tendon alone and the semitendinosus and gracilis tendon graft fashioning techniques concerning knee stability and clinical outcome after anatomic double-bundle ACL reconstruction. Methods A prospective study was performed on 120 patients who underwent anatomic double-bundle ACL reconstruction according to the graft fashioning technique. The authors developed the protocol to use hamstring tendon autografts. When the harvested doubled semitendinosus tendon is thicker than 6 mm, each half of the semitendinosus tendon is doubled and used for the anteromedial (AM) and posterolateral (PL) bundle grafts (Group I). On the other hand, when the harvested semitendinosus This paper was presented at the 8th Biennial International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Congress, 15–19 May 2011, Rio de Janeiro, Brazil. Y. Inagaki E. Kondo (&) N. Kitamura J. Onodera K. Yasuda Department of Sports Medicine and Joint Surgery, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan e-mail: [email protected] Y. Inagaki Y. Tanaka Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan T. Yagi Department of Orthopedic Surgery, Yamanote-dori Yagi Hospital, Sapporo, Hokkaido, Japan
tendon is under 6 mm in thickness, the gracilis tendon is harvested additionally. The distal half of the semitendinosus and gracilis tendons are doubled and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon is doubled and used for the PL bundle grafts (Group II). Sixty-one patients were included in Group I, and 59 patients in Group II. The two groups were compared concerning knee stability and clinical outcome 2 years after surgery. Results The postoperative side-to-side anterior laxity averaged 1.3 mm in both groups, showing no statistical difference. There were also no significant differences between the two groups concerning the peak isokinetic torque of the quadriceps and the hamstrings, the Lysholm knee score, and the International Knee Documentation Committee evaluation. Conclusion There were no significant differences between the two graft fashioning techniques after anatomic double-bundle ACL reconstruction concerning knee stability and postoperative outcome. The present study provided orthopedic surgeons with important information on double-bundle ACL reconstruction with hamstring tendons. Level of evidence Level II; prospective comparative study.
Introduction The normal anterior cruciate ligament (ACL) consists of the anteromedial (AM) and posterolateral (PL) bundles, which have different functions [1, 2]. The idea of reconstructing both bundles was proposed in the 1980s [3]. In the early 2000s, since Yasuda et al. [4] reported a new concept of anatomic reconstruction of the AM and PL bundles of the ACL with 2-year clinical results superior to conventional
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single-bundle ACL reconstruction, a number of anatomic, biomechanical, and clinical studies on the anatomic doublebundle reconstruction procedures have been conducted in the field of ACL reconstruction, and several clinical trials have found that postoperative knee stability is superior in the anatomic double-bundle reconstruction compared with conventional single-bundle reconstruction [5–13]. The essence of ACL reconstruction is grafting tendon bundles across the knee joint. Therefore, graft selection, preparation, and fixation are critical factors to ensure ACL reconstruction leads to clinical success [14]. However, it has been well established that the weak points of the hamstring tendon graft fixed with sutures to bone are (1) low stiffness of the graft-suture-bone complex, (2) rapid relaxation of the graft tension after surgery, and (3) difficulty in tension control during graft fixation [15, 16]. Therefore, the authors have developed hamstring tendon ‘hybrid’ autografts which consist of hamstring tendon connected in series with commercially available polyester tape (Leeds-Keio Artificial Ligament, Neo Ligament, Leeds, England, United Kingdom) [10, 15, 16]. The hybrid graft was used to address the above described weak points based on biomechanical studies [17–19]. In anatomic double-bundle ACL reconstruction, the authors developed the protocol described below to fully utilize the limited amount of hamstring tendon. Concerning the graft preparation in double-bundle ACL reconstruction, a few clinical comparisons between different fashioning techniques have been reported [20, 21]. On the basis of clinical results [8, 9, 13], the authors hypothesized that there are no significant differences between the semitendinosus tendon alone and semitendinosus and gracilis tendon graft fashioning methods concerning knee stability and clinical outcome after anatomic double-bundle ACL reconstruction. The purpose of this study was to test this hypothesis.
routinely performed computed digital radiographs and MRI scans, and the findings at surgery. Patients with a combined ligament injury in the posterior cruciate ligament, the lateral collateral ligament, the PL corner structures of the knee, and medial collateral ligament (grade 3) were excluded from this study. In addition, patients with any previous operations for ligament injuries, a concurrent fracture, or severe osteoarthritis were excluded. The time from onset of injury to surgery was 1 month or more. This clinical study design had been accepted by the institutional review board clearance in this hospital before commencement, based on the described study design and informed consent. In 2004, 2005 and 2006, 55, 42, and 46 patients, respectively, were enrolled in this study. Patients were informed that they were going to be in a study, and that they could choose another graft type if they did not wish to participate in this study. Other surgical options in this hospital included single-bundle reconstruction with hamstring tendon autografts, or a bone-patella tendon-bone autograft. The patients who did not wish to take part in this study were not enrolled. Two years after surgery, each patient was examined with the standard clinical evaluation methods. One hundred and twenty patients (83.9 %) underwent the same followup examinations, while 23 patients were lost (Fig. 1); 16 patients were excluded from the evaluation because there were no muscle torque data taken at the final follow-up. Two patients were excluded for contralateral ACL injury and ipsilateral revision ACL surgery, respectively. Finally, three patients did not attend the regular follow-up after ACL reconstruction up to 2 years postoperatively. There were 68 men and 52 women with an average age of 27 years at the time of surgery. In Group I, 61 patients underwent anatomic double-bundle ACL reconstruction using the semitendinosus tendon alone. In Group II, 59 patients underwent anatomic double-bundle ACL
Materials and methods
143 patients 2004: 55 patients 2005: 42 patients 2006: 46 patients
Study design A prospective, comparative, cohort study was conducted in 143 patients who underwent anatomic double-bundle ACL reconstruction using hamstring tendon autografts in one of the author’s affiliate hospitals between 2004 and 2006. Based on the graft fashioning protocol described below, the authors performed anatomic double-bundle reconstruction using semitendinosus tendon autograft or semitendinosus and gracilis tendon autografts for all patients. Each patient showed an ACL deficiency in the unilateral knee at the time of surgery. The diagnosis of injured ligaments was made based on a detailed history of the knee injury, physical examinations on pathologic status and abnormal laxity,
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Group I
Group II
75 patients
> 2-yr f/u
61 patients
68 patients
Loss of f/u
23 patients
> 2-yr f/u
59 patients
Fig. 1 Flowchart demonstrating patient movement through the study
Hamstring graft in DB ACL reconstruction Table 1 Comparison of background factors of patients between Groups I and II Group I (N = 61)
Group II (N = 59)
P value 0.320
Age (years)
28.2 ± 11.9
26.2 ± 10.3
Male/female (patients)
35/26
33/26
0.873
Height (cm) Weight (kg)
166.4 ± 7.9 62.5 ± 9.3
166.3 ± 8.4 65.6 ± 10.7
0.954 0.0954
Interval between injury and operation (months)
23.6 ± 50.4
16.1 ± 46.3
0.394
Meniscal injury (patients)a
9:4
12:5
0.343
Values are expressed as mean ± SD a
The number of patients with partial resection versus that with meniscus repair
Fig. 2 The hamstring tendon hybrid autografts for anatomic doublebundle anterior cruciate ligament reconstruction. The lengths of autografts were 60–70 and 50–60 mm for AM and PL bundles, respectively. AM anteromedial, PL posterolateral
Graft fashioning technique reconstruction using the semitendinosus and gracilis tendons. There were no significant differences between the two groups concerning age, gender, height, weight, and the time to surgery (Table 1). One senior orthopedic surgeon (K.Y.) performed all operations using the same procedure for each group. At the time of reconstruction, the medial or lateral meniscus was partially resected in 21 patients, and repaired in nine patients (Table 1). No treatment was administered for softening or fissuring of the articular cartilage. In each group, an approximately 3-cm-long incision was made in the antero-medial portion of the proximal tibia, and the hamstring tendon was harvested using a tendon stripper. Concerning the graft selection for each patient, first, a surgeon harvested the semitendinosus tendon. When the harvested doubled distal portion of the semitendinosus tendon was thicker than 6 mm, the semitendinosus tendon was used for the AM and PL bundle graft. On the other hand, when the harvested doubled distal portion of the semitendinosus tendon was under 6 mm in thickness, the gracilis tendon was harvested additionally. The length of the semitendinosus tendon or/and gracilis tendon was measured using a linear scale. The distance from the tibial insertion of the tendon to its tendinous termination into muscle was defined as the length of the tendon [22]. The cross-sectional area of the tendon portion was measured with a cylindrical gauge (Sizing system, Acufex, Smith & Nephew Endoscopy, Andover, Massachusetts). After the harvested tendon was passed through each stainless tube, the greatest diameter of the gauge was defined as the diameter of the tendon. Each reconstruction procedure was performed using the arthroscopically assisted 1-incision (transtibial tunnel) technique. Each graft was secured with EndoButtons-CL (Smith & Nephew Endoscopy) on the femur and with two staples (Meira, Nagoya, Japan) on the tibia. All patients underwent postoperative management with the same rehabilitation protocol [9, 23].
In Group I, when the harvested doubled semitendinosus tendon was thicker than 6 mm, the semitendinosus tendon was cut into two parts. The distal half of the semitendinosus tendon was doubled (two strands) with side-by-side sutures and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon was also doubled (two strands) with side-by-side sutures and used for the PL bundle graft (Fig. 2). The lengths of the autografts were 60–70 and 50–60 mm for the AM and PL bundle grafts, respectively. The autografts were connected in series with 10-mm-width polyester tape (Leeds-Keio Artificial Ligament, Neo Ligament) at the tibial side and attached to the Endobutton-CL (Smith & Nephew Endoscopy) (Fig. 2). The size of the Endobutton-CL was adjusted so that an autogenous tendon portion of 15–20 mm was located in the femoral and tibial tunnels. In Group II, when the harvested semitendinosus tendon was under 6 mm in thickness, the gracilis tendon was harvested additionally. The distal half of the semitendinosus and the gracilis tendons were doubled (four strands) with side-by-side sutures and used for the AM bundle graft, and the remaining proximal half of the semitendinosus tendon was doubled (two strands) with side-by-side sutures and used for the PL bundle grafts. However, when the doubled proximal half of the semitendinosus tendon was under 5 mm in thickness, the proximal half of the gracilis tendon was added additionally. Then, three or four strand semitendinosus and gracilis tendons were used for the PL bundle grafts. After that, the two hamstring hybrid autografts were fashioned in the same manner as in Group I. Anatomic double-bundle ACL reconstruction procedure The details of this procedure have been previously described in the literature [4, 13]. Briefly, a tibial tunnel for the PL bundle was created. To insert a guidewire, a hole-in-
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one guide (Wire-navigator, Smith & Nephew Endoscopy, Tokyo, Japan) was used. The tibial indicator of the Navi-tip was placed at the center of the PL bundle footprint on the tibia. Then, keeping the tibial indicator at this point, the femoral indicator was aimed at the center of the PL bundle attachment on the femur. A guidewire was drilled through the sleeve in the tibia. Then, a guidewire for AM bundle reconstruction was inserted in the same manner. Using a wire-navigator, the femoral indicator was aimed at the center of the AM bundle attachment on the femur. The two tibial tunnels were made with a cannulated drill corresponding to the measured diameter of the prepared substitute. To create two femoral tunnels for the AM and PL bundles in the lateral condyle, first, a guidewire was drilled at the center of the femoral attachment of the AM bundle through the AM tibial tunnel by use of an offset guide (transtibial femoral ACL Drill Guide, Arthrex, Naples, FL, USA). Using the inserted guidewire, a tunnel was made with a 4.5-mm cannulated drill. The length of the tunnel was measured with a scaled probe. Then, the portal for an arthroscope was changed to the medial infrapatellar portal. A guidewire was inserted at the center of the PL bundle attachment on the femur through the PL tibial tunnel. A 4.5-mm-diameter tunnel was drilled, and its length was measured in the same manner. Finally, two sockets were created for the AM and PL bundles, respectively, with cannulated drills, the diameter of which was matched to the two grafts prepared with the technique described above. Finally, the graft for the PL bundle was introduced through the tibial tunnel to the femoral tunnel by use of a passing pin. The EndoButton was flipped on the femoral cortical surface. Then, the graft for the AM bundle was placed in the same manner. For graft fixation, an assistant surgeon simultaneously applied tension of 30 N to each graft using two tensiometers (Meira, Nagoya, Japan) at 10° of knee flexion for 2 minutes. Then, a surgeon simultaneously secured the two tape portions onto the tibia using two spiked staples (Meira) in the turn-buckle fashion. Clinical evaluations Each patient underwent clinical examination 2 years after surgery. The side-to-side anterior laxity was measured with a KT-2000 arthrometer (MEDmetric, San Diego, CA, USA) at 30° of knee flexion under an anterior drawer force of 133 N. A well-trained physical therapist who was blinded to the procedure collected the KT-2000 arthrometer results postoperatively. An experienced orthopedic surgeon (E.K.), who was also blinded to the procedure, performed the pivot-shift test, the results of which were subjectively evaluated by the examiner. In evaluation of the pivot-shift test [4, 9], the indication of ?? was defined when the
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examiner felt a sudden rotational slip movement between the tibia and femur, a so-called jog, during the test for the injured knee. The ?? pivot-shift test result showed an obvious failure of the ACL function. The indication of ? was defined when the examiner felt some difference in the rotational movement during the test between the injured and uninjured knees but did not obviously feel the sudden rotational slip movement. This condition showed some insufficiency of the ACL function but did not show a complete failure of the ACL. As to overall evaluation, the Lysholm knee score (maximum score 100 points) and the International Knee Documentation Committee (IKDC) form were used. Peak isokinetic torque of the quadriceps and the hamstrings was measured at 60 °/s of angular velocity using KIN-COM (Chattecx Corp, Chattanooga, TN, USA) in both knees after surgery. Muscle torque as measured postoperatively in the uninvolved knee was represented as a ratio (percentage) to the uninvolved value. Statistical analysis All data were shown as means with SD. For each parameter, unpaired Student’s t test and Chi-square test were performed between the two groups. When a significant result was obtained, a post hoc test with a Fisher protected least significant difference test was made for multiple comparisons. Correlations between the side-to-side anterior laxity and the tunnel diameter were calculated by use of the Pearson correlation coefficient. A commercially available software program (StatView, SAS Institute, Cary, NC, USA) was used for statistical calculation. The significance level was set at P = 0.05.
Results In Group I, the lengths and the diameters of the semitendinosus tendon averaged 254.4 and 4.7 mm (Table 2), respectively. In Group II, the lengths and the diameters of the semitendinosus tendon averaged 235.2 and 4.4 mm (Table 2), respectively, while those of the gracilis tendon averaged 206.0 and 3.4 mm. The length of the semitendinosus tendons in Group I was significantly longer than those of the semitendinosus tendons (P \ 0.0001) in Group II. The diameter of the semitendinosus tendons in Group I was also significantly thicker than those of the semitendinosus tendons (P \ 0.0001) in Group II. Concerning the diameter of the AM bundle graft, Group II was significantly greater (P \ 0.0001) than Group I (Table 2). Regarding the diameter of the PL bundle graft, there were no significant differences between the two groups. The distribution of the AM and PL bundle graft diameter in Groups I and II are shown in Fig. 3.
Hamstring graft in DB ACL reconstruction
The postoperative side-to-side anterior laxity measured at 30° of knee flexion with the KT-2000 averaged 1.3 mm in both groups, showing no statistical difference. In each group, there was no significant relationship between the femoral and tibial tunnel diameter of the AM and PL grafts and the postoperative side-to-side anterior laxity (correlation coefficients range; r = -0.171 to 0.17, P = 0.1189–0.9613). Regarding the pivot-shift test (Table 3), the Chi-square test Table 2 The lengths and diameters of the semitendinosus and gracilis tendons, and the diameters of the anteromedial and posterolateral tunnels of the femur and tibia in Groups I and II Group I (N = 61)
Group II (N = 59)
P value
Discussion
Semitendinosus tendon Length (mm)
254.4 ± 15.9
235.2 ± 22.9
\0.0001
Diameter (mm)
4.7 ± 0.5
4.4 ± 0.5
\0.0001
Gracilis tendon Length (mm)
Not applicable
Diameter (mm)
206.0 ± 26.0 3.4 ± 0.5
Anteromedial bundle graft Diameter (mm)
6.2 ± 0.5
6.9 ± 0.5
\0.0001
5.9 ± 0.3a
0.639
Posterolateral bundle graft Diameter (mm)
showed no significant difference between the two groups. Concerning the range of knee motion, there was no patient with loss of terminal knee extension in Group I. On the other hand, three patients had loss of knee extension over 5° in Group II. In both groups, there was no patient with loss of terminal knee flexion over 15°. Regarding the ratio of the involved limb to the contralateral limb about the peak isokinetic torque of the quadriceps and the hamstrings, there were no significant differences between the two groups (Table 3). There were also no significant differences between the two groups concerning the Lysholm knee score, and the IKDC evaluation (Table 3).
5.9 ± 0.4
Values are expressed as mean ± SD a
In 19 patients, the semitendinosus and gracilis tendons were used for the PL bundle graft
This study demonstrated that there are no significant differences between the semitendinosus tendon alone and the semitendinosus and gracilis tendon graft fashioning techniques concerning the postoperative side-to-side anterior laxity, the peak muscle torque, the range of knee motion, the Lysholm knee score, and the IKDC evaluation 2 years after anatomic double-bundle ACL reconstruction. The postoperative side-to-side anterior laxity measured with KT-2000 averaged 1.3 mm in both groups. The Lysholm score and the IKDC evaluation achieved good results in both groups compared with the previously reported results after anatomic double-bundle reconstruction [4–6,
Group I (AM bundle graft)
50
40
Patients
Patients
40 30 20
30 20 10
10 0
Group I (PL bundle graft)
50
0 5
5.5
6
6.5
7
7.5
8
5
5.5
Group II (AM bundle graft)
7
7.5
8
7.5
8
Group II (PL bundle graft)
50
40
40
Patients
Patients
6.5
Diameter (mm)
Diameter (mm) 50
6
30 20 10
30 20 10
0
0 5
5.5
6
6.5
7
Diameter (mm)
7.5
8
5
5.5
6
6.5
7
Diameter (mm)
Fig. 3 The distribution of the AM and PL bundle graft diameters in Groups I and II. AM anteromedial, PL posterolateral
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Y. Inagaki et al. Table 3 Comparisons in the clinical outcome between Groups I and II Group I (N = 61)
Group II (N = 59)
P value
1.3 ± 1.4
1.3 ± 1.5
0.825
(-) (?)
48 patients 13 patients
45 patients 14 patients
(??)
0 patient
0 patient
Loss of extension ([5°)
0 patient
3 patients
Loss of flexion ([15°)
Anterior laxitya (mm) Pivot-shift test
0.751
Loss of knee motion
0.0745 0 patient
0 patient
Peak isokinetic torque of the quadricepsb (%)
86.4 ± 15.9
87.6 ± 14.6
0.661
Peak isokinetic torque of the hamstringsb (%) Lysholm knee score (points)
93.3 ± 17.8
92.6 ± 15.1
0.842
97.0 ± 4.6
96.7 ± 5.4
IKDC score
0.775 0.593
A (normal)
46 patients
44 patients
B (nearly normal)
15 patients
14 patients
C (nearly abnormal)
0 patient
1 patient
D (abnormal)
0 patient
0 patient
Values are expressed as mean ± SD a
Difference of anterior knee laxity between treated knee and uninjured knee (mm)
b
Ratio of treated knee to uninjured knee (%)
8–11, 13, 23]. The results indicated that this graft fashioning procedure may be an effective method in restoring knee stability in anatomic double-bundle ACL reconstruction. The reason for the similar results in the two groups is that the difference in tunnel diameter between the two groups was\1 mm, so it may not affect the maturation and the function of the grafts. Recently, Zhao et al. [21] compared the clinical results of a double-bundle ACL reconstruction with four strands versus eight strands of hamstring tendon graft. They reported that a double-bundle ACL reconstruction with eight strands yields significantly better results than a double-bundle ACL reconstruction with four strands, concerning the side-to-side difference in anterior knee laxity, the IKDC subjective result, and the Lysholm score. However, Zhao et al. [21] described that their double-bundle reconstruction was not an anatomic reconstruction. On the tibial side, the inner openings of both bundles were 7-mm anterior to the tip of the tibial spine and located on a medial–lateral line, side by side. In addition, Li [24] pointed out that the diameter of an eight-strand hamstring tendon (mean diameter 8 mm, range 6–11 mm) was significantly greater than that of a native ACL. Therefore, notchplasty was performed in more patients in the eightstrand hamstring tendon group than in the four-strand group. Because of the obviously decreased volume of the knee
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cavity following reconstruction, impingement between the eight-strand hamstring graft and the posterior cruciate ligament or the femoral notch might occur, which could impair the strength and reduce the longevity of the graft, and even the posterior cruciate ligament, because of intermittent shear force following knee motion. In this study, the mean AM bundle diameters were 6.2 and 6.9 mm in Groups I and II, respectively. Therefore, in the author’s double-bundle reconstruction, most patients did not show graft impingement, because the placed AM and PL grafts were relatively thin and anatomically twisted in the intercondylar notch. Therefore, the authors did not perform the notchplasty except in chronic cases. However, the authors found some tendency of a difference in postoperative loss of knee extension between the two procedures. Namely, three patients showed loss of knee extension by 5°–10° in Group II, while there were no patients with loss of knee extension in Group I. From the clinical viewpoint, the loss of knee extension is one of the pathological conditions that should be absolutely avoided after ACL reconstruction [25]. Even though this difference was not statistically significant, the authors believe it was clinically important for avoiding graft impingement. Therefore, surgeons should consider the graft thickness for graft preparation using the semitendinosus and gracilis tendon graft fashioning techniques. Recently, Niki et al. [20] reported the clinical results of anatomic double-bundle ACL reconstruction by use of bone-patellar tendon-bone and gracilis tendon grafts and compared them with the results of double-bundle ACL reconstruction by use of semitendinosus tendon or semitendinosus and gracilis tendon grafts. At 2 years follow-up, there were no significant differences in terms of the Lysholm score, Tegner activity level, and IKDC evaluation among the three groups. In their hamstring double-bundle ACL reconstruction, two double-looped semitendinosus tendons were prepared for both the AM and PL bundle grafts when the semitendinosus tendon was 24 cm or longer. Gracilis tendon was harvested for the PL bundle graft and double looped only when the semitendinosus tendon was \24 cm long. This protocol was different from the authors’ graft preparation protocol. In our protocol, the authors consider that a 6-mm diameter may be the necessary thickness of the AM hamstring graft in ACL reconstruction, based on previous cadaveric studies [26–28]. Although, in general, long hamstring tendons have thick diameters, while short tendons have thin diameters, surgeons should consider not only the graft length but also the graft thickness for graft preparation. There are many reports on the effect of additional gracilis tendon harvesting in single bundle ACL reconstruction [29–34]. Tashiro et al. [34] reported that patients with reconstructed single bundle ACLs with semitendinosus and gracilis tendons showed lower isokinetic and isometric muscle peak torque in the deep knee flexion range
Hamstring graft in DB ACL reconstruction
than those with semitendinosus only. Segawa et al. [33] and Gobbi et al. [31] also reported the weakness of internal rotation muscle strength in those with semitendinosus and gracilis tendons than those with semitendinosus tendon only. On the other hand, Ardern et al. [30] showed no statistical difference concerning the muscle strength between the groups which were grouped in the same manner as this study. Nakamura et al. [32] reported a decrease in maximum standing knee flexion angle of the involved limb compared to the uninvolved limb in patients who underwent ACL reconstruction with semitendinosus and gracilis tendons, compared with those with semitendinosus tendon only. On the contrary, the above mentioned Ardern et al. [30] reported that there was no correlation between the maximum standing knee flexion angle and the isometric muscle torque at 105° of knee flexion, so it should not be used as the clinical parameter of postoperative muscle strength. Therefore, in addition to long-term results, more detailed evaluation on the muscle strength such as the value at deep knee flexion, and the internal muscle torque of knee is needed. There were several limitations to this study. The first limitation is that the patients were not truly randomized because the authors used the originally developed graft fashioning protocol in anatomic double-bundle ACL reconstruction. Although age, gender, height, weight, and the time from injury to surgery were not completely the same between the two groups, there were no statistical differences. The second limitation is that the authors only evaluated the peak isokinetic torque of the quadriceps and the hamstrings at 60 °/s of angular velocity after ACL reconstructions with hamstring tendon graft. The third limitation is that the follow-up period was only 2 years. Therefore, at the present time, the authors cannot speculate as to whether there will be differences between the two different graft fashioning techniques in terms of long-term outcome of knee function and return to sports. The fourth limitation is that the authors did not precisely evaluate the ability of sports performance because, in the short-term results, these parameters are commonly favorable, independent of reconstruction procedures. In the future, the authors should conduct a long-term follow-up study to compare the subjective evaluation and the ability of sports performance between the two groups. However, beyond these limitations, the present study provided orthopedic surgeons with important information on double-bundle ACL reconstruction with hamstring tendons.
Conclusion In this study, the authors did not find any significant differences between the two graft types of hamstring tendon
hybrid autograft (semitendinosus only, or semitendinosus and gracilis tendons) after anatomic double-bundle ACL reconstruction, concerning postoperative side-to-side anterior laxity, peak muscle torque, range of knee motion, Lysholm knee score, or IKDC evaluation 2 years after the operation. Acknowledgments This research was supported in part by Grantsin-Aid for scientific research (21500400) from the Ministry of Education, Science and Culture, Japan. The authors report no conflict of interest.
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