Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-3076-4
KNEE
Comparison of results after anterior cruciate ligament reconstruction using a four-strand single semitendinosus or a semitendinosus and gracilis tendon Hee-Soo Kyung • Hyun-Joo Lee • Chang-Wug Oh Han-Pyo Hong
•
Received: 11 February 2013 / Accepted: 8 May 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purposes To compare the clinical and functional results of anterior cruciate ligament (ACL) reconstruction using an autologous four-strand single semitendinosus (ST) tendon or a ST and gracilis tendon. It was hypothesized that successful ACL reconstruction using a single ST tendon without the gracilis tendon could provide comparable knee stability and reduce donor site morbidity. Methods This study evaluated 144 cases of single-bundle ACL reconstruction using an autologous hamstring tendon. The ST group included 85 cases of reconstruction using a single ST tendon, and the ST/G group included 59 cases of reconstruction using a ST tendon and a gracilis tendon. An extracortical suspension device and a suture tied around a screw post with an additional bioabsorbable screw were used to fix the femoral and tibial tunnels, respectively. Clinical evaluations involved the Lachman, pivot-shift, and one-leg hop tests; an isokinetic test; a KT-2000 arthrometer; an assessment of return to pre-injury activities; and Lysholm, Tegner activity, and International Knee Documentation Committee (IKDC) subjective scores. Results No significant differences were found between the ST and ST/G groups with respect to the Lysholm, Tegner activity, and subjective IKDC scores; the Lachman, pivot-shift, and one-leg hop tests; KT-2000 arthrometer side-to-side differences; or return to pre-injury activities. However, mean peak torque deficit, as determined using the isokinetic test during flexion at 60°/s, was significantly lower in the ST group than in the ST/G group (p = 0.047).
H.-S. Kyung (&) H.-J. Lee C.-W. Oh H.-P. Hong Department of Orthopaedic Surgery, School of Medicine, Kyungpook National University Hospital, 130 Dongduk-Ro Jung-Gu, Daegu 700-721, Korea e-mail: [email protected]
Conclusion This study showed good results for ACL reconstruction using a single ST tendon without deterioration of stability. This provides the evidence that ACL reconstruction using a single ST tendon without the gracilis tendon decreases donor site morbidity without compromising joint stability. Level of evidence IV. Keywords Anterior cruciate ligament reconstruction Semitendinosus Gracilis Single semitendinosus
Introduction Many options are available for anterior cruciate ligament (ACL) reconstruction, including an autologous bone–patellar tendon–bone graft, a hamstring tendon graft, and an allograft. The bone–patellar tendon–bone graft is more likely to result in normal knee joint laxity and less incidence of significant flexion loss. In contrast, hamstring grafts reduce the incidence of patellofemoral crepitus, kneeling pain, and extension loss [10]. Holm et al. [11] published a randomized study with a 10-year follow-up, comparing knee function and osteoarthritis prevalence after ACL reconstruction for a four-strand hamstring autograft versus a bone–patellar tendon–bone autograft. No significant difference between clinical outcomes was found between the two grafts at 10 years postoperatively, although osteoarthritis prevalence was significantly higher in the operated than in the contralateral leg. Pinczewski et al. [21] published a comparative meta-analysis on bone–patellar tendon–bone and hamstring autografts obtained in two consecutive series with a 10-year follow-up and recommended the hamstring graft as the first choice. A
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significantly higher incidence of radiographic osteoarthritic changes was found in knees reconstructed with a bone–patellar tendon–bone autograft than with a hamstring autograft. Allografts have the advantage of no donor site morbidity and good graft source availability, but they incorporate and remodel more slowly than autografts and introduce risk of inflammatory reactions (chronic effusion) and disease transmission, and exhibit tensile property reductions after sterilization and preservation [23, 24]. Mariscalco et al. [18] published a systematic comparative review on autografted versus non-irradiated allografted tissue for ACL reconstruction and found no significant differences between graft failure rates, postoperative laxities, or patient-reported outcome scores. However, these findings were obtained for patients in their late 20 s and early 30 s; thus, caution was advised regarding extrapolating these findings to younger, more active cohorts. Barrett et al. [3] published a comparative study on ACL graft failure and compared graft types with respect to age and Tegner activity level. In patients aged B25 years, autograft hamstrings and allografts were found to have significantly higher failure rates than bone–patellar tendon– bone autografts, indicating bone–patellar tendon–bone autografts might be a better graft source for young, active individuals. Recently, use of the autologous hamstring tendon has become more common than the patellar tendon for ACL reconstruction [1, 21], and the majority of surgeons use both the semitendinosus (ST) and gracilis tendons to produce a four-strand hamstring tendon [4, 16]. Furthermore, the use of bone–patellar tendon–bone autografts, which were previously considered the ‘‘gold standard,’’ is decreasing owing to high levels of donor site morbidity [4]. However, although hamstring tendon harvesting causes less donor site morbidity than bone–patellar tendon–bone harvesting [16], some authors have suggested that a knee flexion strength deficit may occur [8], and others have reported that the flexion strength deficit in deep knee flexion is more severe [8, 20, 26] after harvesting the ST and gracilis tendons. Accordingly, it appears that ACL reconstruction using ST and gracilis tendons causes greater flexion strength deficit and donor site morbidity than reconstruction using a single ST tendon. The hypothesis of this study was that, if ACL reconstruction using a single four-strand ST tendon without the gracilis tendon could be accomplished, comparable knee stability could be achieved and donor site morbidity is reduced. Accordingly, this study was undertaken to compare the clinical and functional results of ACL reconstruction using an autologous four-strand ST tendon and a gracilis (ST/G) tendon or a single autologous four-strand ST tendon.
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Materials and methods Of 201 patients that underwent single-bundle ACL reconstruction using a hamstring tendon between 2004 and 2010, the medical records of 144 patients were evaluated retrospectively. These were ACL reconstruction cases in which an extracortical suspension device was used for femoral fixation, and a suture tied around a screw post and an additional bioabsorbable screw were used for tibial fixation. Patients in the ST group (N = 85) underwent ACL reconstruction using a single four-strand ST tendon, whereas patients in the ST/G group (N = 59) underwent ACL reconstruction using a four-strand ST tendon and a gracilis tendon. As gender would have affected the results, especially isokinetics muscle strength, only male patients were included [7, 15, 19]. Exclusion criteria were multiple ligament injuries (except a conservatively treated medial collateral ligament [MCL] tear), subtotal or total meniscectomy, or bilateral ACL reconstruction. Mean age in the ST and ST/G groups were 28.0 and 31.3 years, respectively. In both groups, 83.3 % of injuries were sportsrelated. Mean time from injury to index surgery in the ST and ST/G groups were 5.8 and 6.0 months, respectively. There were 27 cases of meniscus injury and six cases of MCL injury in the ST group and 21 cases of meniscus injury and two cases of MCL injury in the ST/G group. Partial meniscectomy and meniscus repair was performed in 13 and 14 cases, respectively, in the ST group, and they were performed in 15 and six cases, respectively, in the ST/ G group. MCL injuries were treated conservatively in both groups. Mean follow-up periods in the ST and ST/G groups were 26.4 and 27.5 months, respectively (Table 1).
Table 1 Demographic data ST group (N = 85)
ST/G group (N = 59)
p value
Age (years)
28.0 ± 10.6
31.3 ± 12.3
n.s.
Follow-up period (months)
26.4 ± 4
27.5 ± 5
n.s.
Injury to index surgery (months)
5.8 ± 8.1
6.0 ± 7.5
n.s.
Associated injuries Meniscus injuries
27
21
n.s.
Meniscus excision
13
15
n.s.
Meniscus repair
14
6
n.s.
6
2
n.s.
70
50
n.s.
45
28
n.s.
25 15
22 9
n.s. n.s.
MCL injury Cause of injury Sports injuries Soccer Other sports Others
Knee Surg Sports Traumatol Arthrosc
Surgical technique The ST tendon was detected at the posteromedial tibial margin and then detached from the periosteal membrane at the proximal tibia. This technique allowed retrieval of an additional 2 cm of ST tendon. The distal end of the ST tendon was sutured with No. 2 Ti-Cron (CovidienÒ, Argyle, NY). If the length of harvested ST tendon was [28 cm, a 7-cm four-strand ST tendon was constructed by double-folding; if the length was \28 cm, the gracilis tendon was harvested, and a 10-cm four-strand ST/G tendon was constructed. The ACL remnant and stump was preserved to the extent possible. A 7-mm diameter tunnel was made to the tibial footprint center of the ACL. The diameter of the four-strand ST tendon was 8.4 mm (7–10 mm) and that of the ST/G tendon was 7.9 mm (6–9 mm, p \ 0.05). The center of the femoral footprint was targeted at the 10:30 (right knee) or 1:30 (left knee) position to make the femoral tunnel. Femoral fixation was performed using extracortical suspension devices (CL-EndoButton, Smith and Nephew, Andover, MA or XO-Button, Linvatec, Largo, FL). Graft cyclic loading was applied 20 times at 50 N. The knee flexion angle for tibial fixation was 20° under 50 N of distal tension. Tibial fixation was performed by tying sutures around a screw post with an additional bioabsorbable screw. The portion of the distal tibial tunnel not filled by the tendon was grafted using bone obtained during reaming of the tibial tunnel. Postoperative rehabilitation was performed using the same protocol in both study groups. Briefly, quadricepsmuscle-strengthening exercises were started immediately after surgery. Weight bearing was allowed as tolerated with an extension-locking brace, and active range of motion exercises were started 2 weeks after surgery. In cases with combined meniscus repair, range of motion exercises was restricted to 90° of flexion until 6 weeks. Closed kinetic chain exercises were allowed until 3 months after surgery, after which open kinetic chain exercises were allowed. Contact sports were allowed after 12 months if extension and flexion power had recovered to 85 % of the normal, contralateral side. Outcome analysis Clinical evaluations were performed using range of motion; the Lachman test; the pivot-shift test; a KT-2000 arthrometer; the one-leg hop test; isokinetic muscle strength; time of return to pre-injury activities; and Lysholm, Tegner activity; and International Knee Documentation Committee (IKDC) subjective scores. A Biodex system 3 pro and MVP dynamometer (Biodex Medical Systems, Shirley, NY) were used for testing isokinetic muscle strength in the sitting position. Briefly, patients
were seated on the Biodex testing device, and peak torque in extension and flexion was measured four times at angular velocities of 60 and 180°/s. Deficits of the involved versus the uninvolved sides were compared between the two study groups. The one-leg hop test was performed three times per leg, and maximal distances were evaluated. The limb symmetric index (involved versus uninvolved sides) was also evaluated. This retrospective study was approved by the Institutional Review Board (certified by the Forum for Ethical Review Committees in the Asian and Western Pacific Region, ID number: 2013-08-009). Statistical analysis Student’s t test was used to analyze parametric continuous data, the Mann–Whitney U test for non-parametric data, and the Chi-square test for non-continuous data. Post hoc power analysis was performed for the peak torque deficit. Post hoc power was 42.5 % for the muscle strength analysis. Statistical significance was accepted for p values of \0.05, and SPSS version 19 (SPSS; Chicago, IL, USA) was used for all analyses.
Results Postoperative ranges of motion recovered to pre-operative ranges in both groups. No significant intergroup differences were observed for the Lachman test; pivot-shift test; Lysholm, Tegner activity; or subjective IKDC scores; side-toside differences, as determined using a KT-2000 arthrometer; or time of return to pre-injury activities (Table 2). The one-leg hop test and limb symmetric index were also not different, but the limb symmetry index of the involved side Table 2 Clinical outcome results ST group (N = 85)
ST/G group (N = 59)
p value
Return to pre-op ROM
85
59
n.s.
Lachman (?)
3/85
2/59
n.s.
Pivot shift (?)
2/85
1/59
n.s.
Lysholm score
92.2 ± 6.4
92.1 ± 5.8
n.s.
Tegner activity score
6 (4–8)
6 (5–8)
n.s.
IKDC subjective score
85.1 ± 7.0
83.2 ± 7.8
n.s.
KT-2000 arthrometer (mm) (side-to-side difference)
2.3 ± 1.1
2.2 ± 0.6
n.s.
Return to pre-injury activity
70/85 (82.3 %)
50/59 (84.7 %)
n.s.
IKDC International Knee Documentation Committee, pre-op ROM pre-operative range of motion
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Knee Surg Sports Traumatol Arthrosc Table 3 Functional one-leg hop test results ST group (N = 85)
ST/G group (N = 59)
p value
Involved (cm)
119.8 ± 12.3
128.6 ± 18.2
n.s.
Uninvolved (cm)
150.3 ± 16.9
155.9 ± 17.1
n.s.
Limb symmetric index (%)
80.8 ± 13.3
83.5 ± 15.8
n.s.
Table 4 Peak torque deficits ST group (N = 85)
ST/G group (N = 59)
p value
60°/s extension (%)
26.8 ± 16.3
29.9 ± 18.4
n.s.
60°/s flexion (%)
19.8 ± 14.1
24.6 ± 17.2
0.047*
180°/s extension (%)
17.3 ± 13.2
18.5 ± 20.3
n.s.
9.9 ± 11.7
10.5 ± 24.9
n.s.
180°/s flexion (%) * p \ 0.05
was less than that of the uninvolved side (ST and ST/G group, 80.8 and 83.5 %, respectively, Table 3). Peak torque deficits measured by isokinetic testing in extension at 60 or 180°/s and in flexion at 180°/s were not different. However, peak torque deficit in flexion at 60°/s was significantly lower in the ST group than in the ST/G group (p = 0.047, Table 4). Deep infection of the knee joint (one case) and a superficial tibial infection (three cases) occurred in the ST group, but both resolved after arthroscopic debridement.
Discussion The most important finding of the present study was that no difference was found between the clinical or functional results of the ST and ST/G groups, although the ST group showed less flexion strength deficit. Previous studies have described hamstring tendon regeneration after harvest. Williams et al. [27] reported that ACL reconstruction with ST and gracilis autograft resulted in marked decreases in volume, cross-sectional area, and length of the ST and gracilis muscles and that the tendons showed partial regeneration at 6 months after surgery. The biceps femoris and semimembranosus muscles appear to compensate for reduced ST and gracilis function. Choi et al. [7] reported that hamstring tendons regenerated after harvest for ACL reconstruction in a high proportion of patients (ST 80 % and gracilis 75.6 %). In addition, proximal shifting of the musculotendinous junction was significantly correlated with flexor deficit as determined by the hyperflexion isokinetic test.
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Some authors have reported muscle strength deficits after ACL reconstruction using a hamstring tendon. Nakamura et al. [20] reported active knee flexion and hamstring strength evaluation results after ACL reconstruction using hamstring tendons at 2 years after surgery. Isokinetic testing showed that, in both ST and ST/G groups, knee flexor strength of the involved leg was less effectively restored at 90° of knee flexion than at the angle at which peak torque was generated. Conversely, no significant intergroup differences were observed in side-to-side ratios of peak flexion torque or flexion torque at 90°. Furthermore, the mean side-to-side ratio at the mean maximal standing knee flexion angle was significantly lower in the ST/G group than in the ST group. Importantly, decreased knee flexor muscle strength following the harvest of hamstring tendons may be more significant than previously estimated, and multiple tendon harvest may affect the range of active knee flexion. Tashiro et al. [26] reported the influence of medial hamstring tendon harvest on knee flexion strength after ACL reconstruction at 18 months after surgery. Tendon harvest significantly reduced hamstring muscle strength at high knee flexion angles ([70°), but the weakness could be minimized by preserving the gracilis tendon. Ardern et al. [2] reported hamstring strength recovery after hamstring tendon harvest for ACL reconstruction at 2 years postsurgery. Both ST and ST/G grafts showed strength deficits of between 3 and 27 % as compared with non-operated limbs, indicating that hamstring strength deficits persist despite successful rehabilitation. However, no significant intergroup differences were found with respect to isometric or isokinetic strengths. In the present study, peak torque deficit in flexion at 60°/s during isokinetic testing was significantly less in the ST group than in the ST/G group (p = 0.047). For four-strand hamstring tendons, a graft of at least 6 cm in length is recommended; thus, the minimum required ST tendon length is 24 cm for a four-strand ST graft [17, 28, 30]. However, to improve fixation in the present study, four-strand ST grafts of at least 7 cm were prepared. In a previous study, we found that a four-strand ST tendon of 7 cm could be prepared if [28 cm of the ST was harvested; this length of the ST was obtainable in 94.5 % of patients [13]. The four-strand ST tendon has a larger diameter than the four-strand ST and gracilis tendons because the ST tendon is thicker. Furthermore, it was possible to obtain an additional 2 cm of ST tendon by including the periosteum, which is believed to enhance tendon healing to the bone tunnel [5, 6, 12]. Questions regarding weak fixation strength arise when only 2 cm of graft is within the bone tunnel. Previous animal studies on the optimal length of soft tissue grafts within bone tunnels concluded that a graft length of over 15 mm does not influence the kinematic or structural
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properties of the knee joint [22, 29, 32]. In addition, previous clinical studies have reported good results for ACL reconstruction using a single ST tendon [9, 14, 25, 31]. The limitations of this study are that it was performed retrospectively, associated injuries differed in the two groups, muscle strengths were not compared in hyperflexion, and correlations between functional test results and flexion strength deficits were not analyzed. Furthermore, the sample size was not calculated adequately because the study had multiple end results, including clinical outcomes (knee stability, clinical score, and return to pre-injury activity) and muscle strength; thus, the statistical power might be low.
Conclusion This study shows that good results can be obtained using a single ST graft without the gracilis tendon for ACL reconstruction without adversely affecting stability and with less donor site morbidity. The clinical relevance of the present study is that it shows ACL reconstruction using a single ST tendon reduces donor site morbidity without compromising joint stability. Acknowledgments This research was supported by the Kyungpook National University Research Fund, 2012.
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8. Coombs R, Cochrane T (2001) Knee flexor strength following anterior cruciate ligament reconstruction with the semitendinosus and gracilis tendons. Int J Sports Med 22:618–622 9. Gobbi A, Domzalski M, Pascual J, Zanazzo M (2005) Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 21:275–280 10. Goldblatt JP, Fitzsimmons SE, Balk E, Richmond JC (2005) Reconstruction of the anterior cruciate ligament: meta-analysis of patellar tendon versus hamstring tendon autograft. Arthroscopy 21:791–803 11. Holm I, Oiestad BE, Risberg MA, Aune AK (2010) No difference in knee function or prevalence of osteoarthritis after reconstruction of the anterior cruciate ligament with 4-strand hamstring autograft versus patellar tendon–bone autograft: a randomized study with 10-year follow-up. Am J Sports Med 38:448–454 12. Kyung HS, Kim SY, Oh CW, Kim SJ (2003) Tendon-to-bone tunnel healing in a rabbit model: the effect of periosteum augmentation at the tendon-to-bone interface. Knee Surg Sports Traumatol Arthrosc 11:9–15 13. Kyung HS, Kim TG, Oh CW, Yoon SH (2009) Anterior cruciate ligament reconstruction with a four-strand single semitendinosus tendon autograft. J Korean Arthrosc Soc 13:138–142 14. Kyung HS, Oh CW, Lee HJ (2011) Clinical evaluation of anterior cruciate ligament reconstruction with remnant-preserving technique: method using single four-strand semitendinosus tendon. J Korean Orthop Assoc 46:60–67 15. Lephart SM, Ferris CM, Riemann BL, Myers JB, Fu FH (2002) Gender differences in strength and lower extremity kinematics during landing. Clin Orthop Relat Res 401:162–169 16. Li S, Chen Y, Lin Z, Cui W, Zhao J, Su W (2012) A systematic review of randomized controlled clinical trials comparing hamstring autografts versus bone–patellar tendon–bone autografts for the reconstruction of the anterior cruciate ligament. Arch Orthop Trauma Surg 132:1287–1297 17. Maeda A, Shino K, Horibe S, Nakata K, Buccafusca G (1996) Anterior cruciate ligament reconstruction with multistranded autogenous semitendinosus tendon. Am J Sports Med 24:504–509 18. Mariscalco MW, Magnussen RA, Mehta D, Hewett TE, Flanigan DC, Kaeding CC (2014) Autograft versus nonirradiated allograft tissue for anterior cruciate ligament reconstruction: a systematic review. Am J Sports Med 42:492–499 19. Myer GD, Ford KR, Barber Foss KD, Liu C, Nick TG, Hewett TE (2009) The relationship of hamstrings and quadriceps strength to anterior cruciate ligament injury in female athletes. Clin J Sport Med 19:3–8 20. Nakamura N, Horibe S, Sasaki S et al (2002) Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons. Arthroscopy 18:598–602 21. Pinczewski L, Roe J, Salmon L (2009) Why autologous hamstring tendon reconstruction should now be considered the gold standard for anterior cruciate ligament reconstruction in athletes. Br J Sports Med 43:325–327 22. Qi L, Chang C, Jian L, Xin T, Gang Z (2011) Effect of varying the length of soft-tissue grafts in the tibial tunnel in a canine anterior cruciate ligament reconstruction model. Arthroscopy 27:825–833 23. Scheffler SU, Schmidt T, Gangey I, Dustmann M, Unterhauser F, Weiler A (2008) Fresh-frozen free-tendon allografts versus autografts in anterior cruciate ligament reconstruction: delayed remodeling and inferior mechanical function during long-term healing in sheep. Arthroscopy 24:448–458 24. Scheffler SU, Unterhauser FN, Weiler A (2008) Graft remodeling and ligamentization after cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 16:834–842
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Knee Surg Sports Traumatol Arthrosc 25. Streich NA, Friedrich K, Gotterbarm T, Schmitt H (2008) Reconstruction of the ACL with a semitendinosus tendon graft: a prospective randomized single blinded comparison of doublebundle versus single-bundle technique in male athletes. Knee Surg Sports Traumatol Arthrosc 16:232–238 26. Tashiro T, Kurosawa H, Kawakami A, Hikita A, Fukui N (2003) 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 31:522–529 27. Williams GN, Snyder-Mackler L, Barrance PJ, Axe MJ, Buchanan TS (2004) Muscle and tendon morphology after reconstruction of the anterior cruciate ligament with autologous semitendinosus– gracilis graft. J Bone Joint Surg Am 86-A:1936–1946 28. Xie G, Huangfu X, Zhao J (2012) Prediction of the graft size of 4-stranded semitendinosus tendon and 4-stranded gracilis tendon for anterior cruciate ligament reconstruction: a Chinese Han patient study. Am J Sports Med 40:1161–1166
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29. Yamazaki S, Yasuda K, Tomita F, Minami A, Tohyama H (2006) The effect of intraosseous graft length on tendon–bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 14:1086–1093 30. Yasumoto M, Deie M, Sunagawa T, Adachi N, Kobayashi K, Ochi M (2006) Predictive value of preoperative 3-dimensional computer tomography measurement of semitendinosus tendon harvested for anterior cruciate ligament reconstruction. Arthroscopy 22:259–264 31. Zamarra G, Fisher MB, Woo SL, Cerulli G (2009) Biomechanical evaluation of using one hamstrings tendon for ACL reconstruction: a human cadaveric study. Knee Surg Sports Traumatol Arthrosc 18:11–19 32. Zantop T, Ferretti M, Bell KM, Brucker PU, Gilbertson L, Fu FH (2008) Effect of tunnel-graft length on the biomechanics of anterior cruciate ligament-reconstructed knees: intra-articular study in a goat model. Am J Sports Med 36:2158–2166
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Comparison of results after anterior cruciate ligament reconstruction using a four-strand single semitendinosus or a semitendinosus and gracilis tendon Hee-Soo Kyung • Hyun-Joo Lee • Chang-Wug Oh Han-Pyo Hong
•
Received: 11 February 2013 / Accepted: 8 May 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purposes To compare the clinical and functional results of anterior cruciate ligament (ACL) reconstruction using an autologous four-strand single semitendinosus (ST) tendon or a ST and gracilis tendon. It was hypothesized that successful ACL reconstruction using a single ST tendon without the gracilis tendon could provide comparable knee stability and reduce donor site morbidity. Methods This study evaluated 144 cases of single-bundle ACL reconstruction using an autologous hamstring tendon. The ST group included 85 cases of reconstruction using a single ST tendon, and the ST/G group included 59 cases of reconstruction using a ST tendon and a gracilis tendon. An extracortical suspension device and a suture tied around a screw post with an additional bioabsorbable screw were used to fix the femoral and tibial tunnels, respectively. Clinical evaluations involved the Lachman, pivot-shift, and one-leg hop tests; an isokinetic test; a KT-2000 arthrometer; an assessment of return to pre-injury activities; and Lysholm, Tegner activity, and International Knee Documentation Committee (IKDC) subjective scores. Results No significant differences were found between the ST and ST/G groups with respect to the Lysholm, Tegner activity, and subjective IKDC scores; the Lachman, pivot-shift, and one-leg hop tests; KT-2000 arthrometer side-to-side differences; or return to pre-injury activities. However, mean peak torque deficit, as determined using the isokinetic test during flexion at 60°/s, was significantly lower in the ST group than in the ST/G group (p = 0.047).
H.-S. Kyung (&) H.-J. Lee C.-W. Oh H.-P. Hong Department of Orthopaedic Surgery, School of Medicine, Kyungpook National University Hospital, 130 Dongduk-Ro Jung-Gu, Daegu 700-721, Korea e-mail: [email protected]
Conclusion This study showed good results for ACL reconstruction using a single ST tendon without deterioration of stability. This provides the evidence that ACL reconstruction using a single ST tendon without the gracilis tendon decreases donor site morbidity without compromising joint stability. Level of evidence IV. Keywords Anterior cruciate ligament reconstruction Semitendinosus Gracilis Single semitendinosus
Introduction Many options are available for anterior cruciate ligament (ACL) reconstruction, including an autologous bone–patellar tendon–bone graft, a hamstring tendon graft, and an allograft. The bone–patellar tendon–bone graft is more likely to result in normal knee joint laxity and less incidence of significant flexion loss. In contrast, hamstring grafts reduce the incidence of patellofemoral crepitus, kneeling pain, and extension loss [10]. Holm et al. [11] published a randomized study with a 10-year follow-up, comparing knee function and osteoarthritis prevalence after ACL reconstruction for a four-strand hamstring autograft versus a bone–patellar tendon–bone autograft. No significant difference between clinical outcomes was found between the two grafts at 10 years postoperatively, although osteoarthritis prevalence was significantly higher in the operated than in the contralateral leg. Pinczewski et al. [21] published a comparative meta-analysis on bone–patellar tendon–bone and hamstring autografts obtained in two consecutive series with a 10-year follow-up and recommended the hamstring graft as the first choice. A
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significantly higher incidence of radiographic osteoarthritic changes was found in knees reconstructed with a bone–patellar tendon–bone autograft than with a hamstring autograft. Allografts have the advantage of no donor site morbidity and good graft source availability, but they incorporate and remodel more slowly than autografts and introduce risk of inflammatory reactions (chronic effusion) and disease transmission, and exhibit tensile property reductions after sterilization and preservation [23, 24]. Mariscalco et al. [18] published a systematic comparative review on autografted versus non-irradiated allografted tissue for ACL reconstruction and found no significant differences between graft failure rates, postoperative laxities, or patient-reported outcome scores. However, these findings were obtained for patients in their late 20 s and early 30 s; thus, caution was advised regarding extrapolating these findings to younger, more active cohorts. Barrett et al. [3] published a comparative study on ACL graft failure and compared graft types with respect to age and Tegner activity level. In patients aged B25 years, autograft hamstrings and allografts were found to have significantly higher failure rates than bone–patellar tendon– bone autografts, indicating bone–patellar tendon–bone autografts might be a better graft source for young, active individuals. Recently, use of the autologous hamstring tendon has become more common than the patellar tendon for ACL reconstruction [1, 21], and the majority of surgeons use both the semitendinosus (ST) and gracilis tendons to produce a four-strand hamstring tendon [4, 16]. Furthermore, the use of bone–patellar tendon–bone autografts, which were previously considered the ‘‘gold standard,’’ is decreasing owing to high levels of donor site morbidity [4]. However, although hamstring tendon harvesting causes less donor site morbidity than bone–patellar tendon–bone harvesting [16], some authors have suggested that a knee flexion strength deficit may occur [8], and others have reported that the flexion strength deficit in deep knee flexion is more severe [8, 20, 26] after harvesting the ST and gracilis tendons. Accordingly, it appears that ACL reconstruction using ST and gracilis tendons causes greater flexion strength deficit and donor site morbidity than reconstruction using a single ST tendon. The hypothesis of this study was that, if ACL reconstruction using a single four-strand ST tendon without the gracilis tendon could be accomplished, comparable knee stability could be achieved and donor site morbidity is reduced. Accordingly, this study was undertaken to compare the clinical and functional results of ACL reconstruction using an autologous four-strand ST tendon and a gracilis (ST/G) tendon or a single autologous four-strand ST tendon.
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Materials and methods Of 201 patients that underwent single-bundle ACL reconstruction using a hamstring tendon between 2004 and 2010, the medical records of 144 patients were evaluated retrospectively. These were ACL reconstruction cases in which an extracortical suspension device was used for femoral fixation, and a suture tied around a screw post and an additional bioabsorbable screw were used for tibial fixation. Patients in the ST group (N = 85) underwent ACL reconstruction using a single four-strand ST tendon, whereas patients in the ST/G group (N = 59) underwent ACL reconstruction using a four-strand ST tendon and a gracilis tendon. As gender would have affected the results, especially isokinetics muscle strength, only male patients were included [7, 15, 19]. Exclusion criteria were multiple ligament injuries (except a conservatively treated medial collateral ligament [MCL] tear), subtotal or total meniscectomy, or bilateral ACL reconstruction. Mean age in the ST and ST/G groups were 28.0 and 31.3 years, respectively. In both groups, 83.3 % of injuries were sportsrelated. Mean time from injury to index surgery in the ST and ST/G groups were 5.8 and 6.0 months, respectively. There were 27 cases of meniscus injury and six cases of MCL injury in the ST group and 21 cases of meniscus injury and two cases of MCL injury in the ST/G group. Partial meniscectomy and meniscus repair was performed in 13 and 14 cases, respectively, in the ST group, and they were performed in 15 and six cases, respectively, in the ST/ G group. MCL injuries were treated conservatively in both groups. Mean follow-up periods in the ST and ST/G groups were 26.4 and 27.5 months, respectively (Table 1).
Table 1 Demographic data ST group (N = 85)
ST/G group (N = 59)
p value
Age (years)
28.0 ± 10.6
31.3 ± 12.3
n.s.
Follow-up period (months)
26.4 ± 4
27.5 ± 5
n.s.
Injury to index surgery (months)
5.8 ± 8.1
6.0 ± 7.5
n.s.
Associated injuries Meniscus injuries
27
21
n.s.
Meniscus excision
13
15
n.s.
Meniscus repair
14
6
n.s.
6
2
n.s.
70
50
n.s.
45
28
n.s.
25 15
22 9
n.s. n.s.
MCL injury Cause of injury Sports injuries Soccer Other sports Others
Knee Surg Sports Traumatol Arthrosc
Surgical technique The ST tendon was detected at the posteromedial tibial margin and then detached from the periosteal membrane at the proximal tibia. This technique allowed retrieval of an additional 2 cm of ST tendon. The distal end of the ST tendon was sutured with No. 2 Ti-Cron (CovidienÒ, Argyle, NY). If the length of harvested ST tendon was [28 cm, a 7-cm four-strand ST tendon was constructed by double-folding; if the length was \28 cm, the gracilis tendon was harvested, and a 10-cm four-strand ST/G tendon was constructed. The ACL remnant and stump was preserved to the extent possible. A 7-mm diameter tunnel was made to the tibial footprint center of the ACL. The diameter of the four-strand ST tendon was 8.4 mm (7–10 mm) and that of the ST/G tendon was 7.9 mm (6–9 mm, p \ 0.05). The center of the femoral footprint was targeted at the 10:30 (right knee) or 1:30 (left knee) position to make the femoral tunnel. Femoral fixation was performed using extracortical suspension devices (CL-EndoButton, Smith and Nephew, Andover, MA or XO-Button, Linvatec, Largo, FL). Graft cyclic loading was applied 20 times at 50 N. The knee flexion angle for tibial fixation was 20° under 50 N of distal tension. Tibial fixation was performed by tying sutures around a screw post with an additional bioabsorbable screw. The portion of the distal tibial tunnel not filled by the tendon was grafted using bone obtained during reaming of the tibial tunnel. Postoperative rehabilitation was performed using the same protocol in both study groups. Briefly, quadricepsmuscle-strengthening exercises were started immediately after surgery. Weight bearing was allowed as tolerated with an extension-locking brace, and active range of motion exercises were started 2 weeks after surgery. In cases with combined meniscus repair, range of motion exercises was restricted to 90° of flexion until 6 weeks. Closed kinetic chain exercises were allowed until 3 months after surgery, after which open kinetic chain exercises were allowed. Contact sports were allowed after 12 months if extension and flexion power had recovered to 85 % of the normal, contralateral side. Outcome analysis Clinical evaluations were performed using range of motion; the Lachman test; the pivot-shift test; a KT-2000 arthrometer; the one-leg hop test; isokinetic muscle strength; time of return to pre-injury activities; and Lysholm, Tegner activity; and International Knee Documentation Committee (IKDC) subjective scores. A Biodex system 3 pro and MVP dynamometer (Biodex Medical Systems, Shirley, NY) were used for testing isokinetic muscle strength in the sitting position. Briefly, patients
were seated on the Biodex testing device, and peak torque in extension and flexion was measured four times at angular velocities of 60 and 180°/s. Deficits of the involved versus the uninvolved sides were compared between the two study groups. The one-leg hop test was performed three times per leg, and maximal distances were evaluated. The limb symmetric index (involved versus uninvolved sides) was also evaluated. This retrospective study was approved by the Institutional Review Board (certified by the Forum for Ethical Review Committees in the Asian and Western Pacific Region, ID number: 2013-08-009). Statistical analysis Student’s t test was used to analyze parametric continuous data, the Mann–Whitney U test for non-parametric data, and the Chi-square test for non-continuous data. Post hoc power analysis was performed for the peak torque deficit. Post hoc power was 42.5 % for the muscle strength analysis. Statistical significance was accepted for p values of \0.05, and SPSS version 19 (SPSS; Chicago, IL, USA) was used for all analyses.
Results Postoperative ranges of motion recovered to pre-operative ranges in both groups. No significant intergroup differences were observed for the Lachman test; pivot-shift test; Lysholm, Tegner activity; or subjective IKDC scores; side-toside differences, as determined using a KT-2000 arthrometer; or time of return to pre-injury activities (Table 2). The one-leg hop test and limb symmetric index were also not different, but the limb symmetry index of the involved side Table 2 Clinical outcome results ST group (N = 85)
ST/G group (N = 59)
p value
Return to pre-op ROM
85
59
n.s.
Lachman (?)
3/85
2/59
n.s.
Pivot shift (?)
2/85
1/59
n.s.
Lysholm score
92.2 ± 6.4
92.1 ± 5.8
n.s.
Tegner activity score
6 (4–8)
6 (5–8)
n.s.
IKDC subjective score
85.1 ± 7.0
83.2 ± 7.8
n.s.
KT-2000 arthrometer (mm) (side-to-side difference)
2.3 ± 1.1
2.2 ± 0.6
n.s.
Return to pre-injury activity
70/85 (82.3 %)
50/59 (84.7 %)
n.s.
IKDC International Knee Documentation Committee, pre-op ROM pre-operative range of motion
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Knee Surg Sports Traumatol Arthrosc Table 3 Functional one-leg hop test results ST group (N = 85)
ST/G group (N = 59)
p value
Involved (cm)
119.8 ± 12.3
128.6 ± 18.2
n.s.
Uninvolved (cm)
150.3 ± 16.9
155.9 ± 17.1
n.s.
Limb symmetric index (%)
80.8 ± 13.3
83.5 ± 15.8
n.s.
Table 4 Peak torque deficits ST group (N = 85)
ST/G group (N = 59)
p value
60°/s extension (%)
26.8 ± 16.3
29.9 ± 18.4
n.s.
60°/s flexion (%)
19.8 ± 14.1
24.6 ± 17.2
0.047*
180°/s extension (%)
17.3 ± 13.2
18.5 ± 20.3
n.s.
9.9 ± 11.7
10.5 ± 24.9
n.s.
180°/s flexion (%) * p \ 0.05
was less than that of the uninvolved side (ST and ST/G group, 80.8 and 83.5 %, respectively, Table 3). Peak torque deficits measured by isokinetic testing in extension at 60 or 180°/s and in flexion at 180°/s were not different. However, peak torque deficit in flexion at 60°/s was significantly lower in the ST group than in the ST/G group (p = 0.047, Table 4). Deep infection of the knee joint (one case) and a superficial tibial infection (three cases) occurred in the ST group, but both resolved after arthroscopic debridement.
Discussion The most important finding of the present study was that no difference was found between the clinical or functional results of the ST and ST/G groups, although the ST group showed less flexion strength deficit. Previous studies have described hamstring tendon regeneration after harvest. Williams et al. [27] reported that ACL reconstruction with ST and gracilis autograft resulted in marked decreases in volume, cross-sectional area, and length of the ST and gracilis muscles and that the tendons showed partial regeneration at 6 months after surgery. The biceps femoris and semimembranosus muscles appear to compensate for reduced ST and gracilis function. Choi et al. [7] reported that hamstring tendons regenerated after harvest for ACL reconstruction in a high proportion of patients (ST 80 % and gracilis 75.6 %). In addition, proximal shifting of the musculotendinous junction was significantly correlated with flexor deficit as determined by the hyperflexion isokinetic test.
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Some authors have reported muscle strength deficits after ACL reconstruction using a hamstring tendon. Nakamura et al. [20] reported active knee flexion and hamstring strength evaluation results after ACL reconstruction using hamstring tendons at 2 years after surgery. Isokinetic testing showed that, in both ST and ST/G groups, knee flexor strength of the involved leg was less effectively restored at 90° of knee flexion than at the angle at which peak torque was generated. Conversely, no significant intergroup differences were observed in side-to-side ratios of peak flexion torque or flexion torque at 90°. Furthermore, the mean side-to-side ratio at the mean maximal standing knee flexion angle was significantly lower in the ST/G group than in the ST group. Importantly, decreased knee flexor muscle strength following the harvest of hamstring tendons may be more significant than previously estimated, and multiple tendon harvest may affect the range of active knee flexion. Tashiro et al. [26] reported the influence of medial hamstring tendon harvest on knee flexion strength after ACL reconstruction at 18 months after surgery. Tendon harvest significantly reduced hamstring muscle strength at high knee flexion angles ([70°), but the weakness could be minimized by preserving the gracilis tendon. Ardern et al. [2] reported hamstring strength recovery after hamstring tendon harvest for ACL reconstruction at 2 years postsurgery. Both ST and ST/G grafts showed strength deficits of between 3 and 27 % as compared with non-operated limbs, indicating that hamstring strength deficits persist despite successful rehabilitation. However, no significant intergroup differences were found with respect to isometric or isokinetic strengths. In the present study, peak torque deficit in flexion at 60°/s during isokinetic testing was significantly less in the ST group than in the ST/G group (p = 0.047). For four-strand hamstring tendons, a graft of at least 6 cm in length is recommended; thus, the minimum required ST tendon length is 24 cm for a four-strand ST graft [17, 28, 30]. However, to improve fixation in the present study, four-strand ST grafts of at least 7 cm were prepared. In a previous study, we found that a four-strand ST tendon of 7 cm could be prepared if [28 cm of the ST was harvested; this length of the ST was obtainable in 94.5 % of patients [13]. The four-strand ST tendon has a larger diameter than the four-strand ST and gracilis tendons because the ST tendon is thicker. Furthermore, it was possible to obtain an additional 2 cm of ST tendon by including the periosteum, which is believed to enhance tendon healing to the bone tunnel [5, 6, 12]. Questions regarding weak fixation strength arise when only 2 cm of graft is within the bone tunnel. Previous animal studies on the optimal length of soft tissue grafts within bone tunnels concluded that a graft length of over 15 mm does not influence the kinematic or structural
Knee Surg Sports Traumatol Arthrosc
properties of the knee joint [22, 29, 32]. In addition, previous clinical studies have reported good results for ACL reconstruction using a single ST tendon [9, 14, 25, 31]. The limitations of this study are that it was performed retrospectively, associated injuries differed in the two groups, muscle strengths were not compared in hyperflexion, and correlations between functional test results and flexion strength deficits were not analyzed. Furthermore, the sample size was not calculated adequately because the study had multiple end results, including clinical outcomes (knee stability, clinical score, and return to pre-injury activity) and muscle strength; thus, the statistical power might be low.
Conclusion This study shows that good results can be obtained using a single ST graft without the gracilis tendon for ACL reconstruction without adversely affecting stability and with less donor site morbidity. The clinical relevance of the present study is that it shows ACL reconstruction using a single ST tendon reduces donor site morbidity without compromising joint stability. Acknowledgments This research was supported by the Kyungpook National University Research Fund, 2012.
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