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ACL Reconstructions via Soft-Tissue (e.g. Hamstring) Autografts (includes articles focused on graft-fixation techniques/devices)
For a brief overview of knee anatomy, physiology, and biomechanics, please click here.
Dr. F.L. Avery's concise and pragmatic synopsis of ACL-graft options can be found under Choosing a Knee-Ligament Graft.
For articles specifically addressing the topic of revision ACL reconstructions, please see Revision Reconstructions: Factors behind ACL-Graft Failures, Outcomes.
For articles focusing on ACL reconstruction in degenerate knees, please see ACL Reconstruction in the Arthritic Knee.
Articles comparing single- versus double-bundle ACL grafting can be found under Choosing a Knee-Ligament Graft.
For a good discussion on the biomechanical shortfalls of the traditional single-bundle ACL graft, and for a good discussion on why dual-bundle ACL grafting is ultimately the way of the future (albeit there are some technical-logistical aspects that need to be addressed first, keeping in mind that double-bundle grafting increases the worries of surgeon error because this technique requires more bone-tunnel-drilling alignment finagling, and keeping in mind that incorrect bone-tunneling [hence surgeon error] is still the major cause of ACL-graft failure), please see the superb February 2007 article Effectiveness of Reconstruction of the Anterior Cruciate Ligament With Quadrupled Hamstrings and Bone-Patellar Tendon-Bone Autografts -- An In Vivo Study Comparing Tibial Internal-External Rotation, by Vasileios Chouliaras et al., in the Knee Biomechanics, Functional Anatomy of ACL and Other Ligaments Subsection, as well as the other articles linked to by that article.
For a comparison of hamstring versus patellar-tendon autografts, both using interference-screw fixation, please see the February 2006 article A Comparison of Bone–Patellar Tendon–Bone and Bone–Hamstring Tendon–Bone Autografts for Anterior Cruciate Ligament Reconstruction, by Akio Matsumoto et al., in the Choosing a Knee-Ligament Graft Subsection.
Two-bundle, four-tunnel anterior cruciate ligament reconstruction, Philippe Colombet et al.; Knee Surgery, Sports Traumatology, Arthroscopy; July 2006, Vol 14, p. 629-636. Comments: These authors found that ACL reconstruction via double-bundle grafting (with four tunnels, i.e. two in each bone) brings promising results. They cautiously note that their results are at least as good as other techniques, and note a trend towards better control of forwards tibial sliding (anterior drawer). Please note that, currently, only the hamstring-type graft is amenable to double-bundle grafting methods. (This article is cross-listed under the Choosing a Knee Ligament Graft Section.)
Clinical Evaluation of Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using Hamstring Tendon Grafts: Comparisons Among 3 Different Procedures, Kazunori Yasuda et al.; Arthroscopy: The Journal of Arthroscopic & Related Surgery; March 2006, Vol 22(3), p. 240-251. Comments: These authors found that double-bundle ACL reconstruction brings substantially better results than single-bundle grafting. Keep in mind that there are two general graft-placement schools of thought: isometric (i.e. the bone tunnels are drilled in locations so that the graft will remain the same length throughout the knee range of motion) and anatomic (i.e. the bone tunnels are centered on the location of the original ACL stumps. (This article is cross-listed under the Choosing a Knee Ligament Graft Section.)
Graft Length Changes in the Bi-Socket Anterior Cruciate Ligament Reconstruction: Comparison Between Isometric and Anatomic Femoral Tunnel Placement, Yasukazu Yonetani et al.; Arthroscopy: The Journal of Arthroscopic & Related Surgery; November 2005, Vol 21(11), p. 1317-1322. Comments: With regards to double-bundle ACL reconstruction techniques, the authors found some subtle differences between anatomic and isometric graft placement nuances. It seems that the anatomic graft placement does a better job of avoiding the concern of graft impingement. (Double-bundle ACL grafts currently are only of the hamstring type. So, with regards to ACL reconstruction in particular, the double-bundle graft technique could merely be considered a subset of hamstring autografting.)
For a comprehensive overview of ACL-grafting techniques and pursuant considerations (including rehabilitation, graft ligamentization, potential problems, and other issues), please see the November 2005 article Clinical Sports Medicine Update: Treatment of Anterior Cruciate Ligament Injuries, Part 2, by Bruce Beynnon et al., in the ACL Reconstructions via Patellar-Tendon Autografts Subsection.
For a comprehensive overview of all the major considerations pertaining to treatment of ACL injuries (including discussions of the impact of concomitant injuries, including damage to other ligaments as well as to articular cartilage and menisci), please see the October 2005 article Clinical Sports Medicine Update: Treatment of Anterior Cruciate Ligament Injuries, Part I, by Bruce D. Beynnon et al., in the ACL Reconstructions via Patellar-Tendon Autografts (includes also Quadriceps Tendon Autografts) Subsection.
Changes in Cross-Sectional Area of Hamstring Anterior Cruciate Ligament Grafts as a Function of Time Following Transplantation , Masayuki Hamada et al.; Arthroscopy, the Journal of Arthroscopy and Related Surgery; August 2005, Vol 21, pages 917-922. Comments: The authors found that the hamstring autograft increases encouragingly in cross-sectional area during the year after surgery. This provides tangible evidence that the ACL graft continues to ligamentize long after the typical formal-rehabilitation period of approximately 6 months. This is something to keep in mind when considering returning to knee-demanding sports. It is prudent to wait a year or longer, and to diligently continue physiotherapy and return-to-sports training (including sports-specific exercises and proprioceptive training, including plyometrics) during the latter half of the first postoperative year. (This article is cross-listed under the Choosing a Knee Ligament Graft Section.)
The Effectiveness of Reconstruction of the Anterior Cruciate Ligament Using the Novel Knot/Press-Fit Technique: A Cadaveric Study, Robert Kilger et al.; The American Journal of Sports Medicine, Baltimore; June 2005, Vol 33, p. 856-863. Comments: This cadaver-based study evaluates the implantation strength of knotting the soft-tissue (hamstring-group) graft and press-fitting it so that the knot sits just proximal to the compact bone in the femur, where the ACL normally inserts into the femur. So, this method results in no surgical hardware in the femur, albeit of course it still requires hardware in the tibia. The authors found that this method brings good promise, albeit they note that further study is required.
Predicting In Vivo Clinical Performance of Anterior Cruciate Ligament Fixation Methods From In Vitro Analysis -- Industrial Tests of Fatigue Life and Tolerance Limits Are More Useful Than Other Cyclic Loading Parameters, Emad S.B. Saweeres et al.; The American Journal of Sports Medicine, Baltimore; May 2005, Vol 33, p. 666-673. Comments: Saweeres et al. found that fatigue testing of anterior cruciate ligament reconstructions more accurately depicts both the huge inter-sample variation and the significant effect of magnitude of loading on life expectancy. The authors found such an approach disappointing, since the tremedously scattered results hampered the drawing of meaningful conclusions. They decided to turn to the industrial materials-testing concept of tolerance limits. They note that basing one's judgements on tolerance limits makes the data easier to interpret. The result is a more conservative, hence safer, estimate of what to expect from a given ACL-graft installation.
Contact pressure in anterior cruciate ligament bone tunnels: Comparison of endoscopic and two-incision technique, Hiroyuki Segawa et al.; Arthroscopy: The Journal of Arthroscopic & Related Surgery; April 2005, Vol 21/4, p. 439-444. Comments: This study delves into the topic of bone-tunnel enlargement (also referred to as widening), a problem often observed with soft-tissue (e.g. hamstring DLSTG) grafts, and thus is of particular relevance to ACL reconstruction via hamstring autografting and also allografting. The authors noted that in their clinical investigation of 87 hamstring-autograft ACL-recon cases (with EndoButton anchorage; note that some concern of the "bungee-cord effect" remains with this method), bone tunnel enlargement occurred in 25% of femoral tunnels and 30% of tibial tunnels. In any case, the gold standard of ACL reconstruction remains the patellar-tendon autograft, since this is the only graft which brings the security of bone-to-bone healing (conferred by the graft having bone plugs at both ends).
For a meta-analysis-type update on the ACL-recon-via-patellar-tendon-versus-hamstring debate, please see the December 2004 article Clinical Sports Medicine Update -- Anterior Cruciate Ligament Reconstruction Autograft Choice: Bone-Tendon-Bone Versus Hamstring -- Does It Really Matter? A Systematic Review, by Kurt P. Spindler et al., in the Choosing a Knee-Ligament Graft Subsection.
Isokinetic Evaluation of Internal/External Tibial Rotation Strength After the Use of Hamstring Tendons for Anterior Cruciate Ligament Reconstruction, Tanya Armour et al.; The American Journal of Sports Medicine, Baltimore; October 2004, Vol 32, p. 1639-1643. Comments: This brilliant and thought-provoking study found that hamstring-graft harvesting engenders a weakening in internal tibial rotation. This weakening remains obvious at 2 years post-op, and appears to be permanent. Other good articles which buttress this same conclusion are Tadokoro-AJSM-Oct04.shtml, Viola-AJSM-Jul00.shtml, Segawa-AJARS-Feb02.shtml and Tashiro-AJSM-Jul03.shtml.
Evaluation of Hamstring Strength and Tendon Regrowth After Harvesting for Anterior Cruciate Ligament Reconstruction, Kou Tadokoro et al.; The American Journal of Sports Medicine, Baltimore; October 2004, Vol 32, p. 1644-1650. Comments: This razor-sharp study involved 28 patients who underwent ACL reconstruction via hamstring (double-looped semitendinosus-gracilis) autografting; follow-up period was a minimum of 2 years. In 22 of those patients, some regrowth of the semitendinosus tendon was found. Meanwhile, regrowth of the gracilis tendon was observed in only 13 patients. Additionally, isometric peak torque, a measure of hamstring-group strength, was markedly reduced. The authors make the sombre conclusions that not only do major hamstring-group weaknesses remain long after the graft has been harvested, but that these weaknesses remain in spite of whatever structural regeneration of the tendon units takes place.
For a comparison of the patellar-tendon versus the hamstring autograft, please see the October 2004 article Anterior Cruciate Ligament Reconstruction: Bone-Patellar Tendon-Bone Compared with Double Semitendinosus and Gracilis Tendon Grafts -- A Prospective, Randomized Clinical Trial, by Paolo Aglietti et al., in the Choosing a Knee-Ligament Graft Subsection.
Bone Density and Insertion Torque as Predictors of Anterior Cruciate Ligament Graft Fixation Strength, Teppo L. N. Järvinen et al.; The American Journal of Sports Medicine, Baltimore; September 2004, Vol 32, p. 1421-1429. Comments: Jarvinen et al. found that the anchorage (fixation) strength of a soft-tissue ACL autograft cannot be foretold by the person's native local bone-mineral density, nor by the torque exerted on the interference screws during the installation process. (This is a cadaver-type study.)
Muscle and Tendon Morphology After Reconstruction of the Anterior Cruciate Ligament with Autologous Semitendinosus-Gracilis Graft, Glenn N. Williams et al.; Journal of Bone and Joint Surgery (American Volume); September 2004, Vol 86, p. 1936-1946. Comments: This study, which unfortunately only looked at patients 4-9 months post-op (a longer-term follow-up would have been highly desirable), found that hamstring-graft harvesting does indeed alter the morphology (physical attributes) of the semitendinosus and gracilis muscles (which are both part of the hamstring group), despite the fact that a certain amount of regeneration does take place. Investigation of the structures post-operatively was done through MRI imaging. (Further comments are provided with the study.)
Semitendinosus Regrowth -- Biochemical, Ultrastructural, and Physiological Characterization of the Regenerate Tendon, Sanjitpal Gill et al.; The American Journal of Sports Medicine, Baltimore; March 2002, Vol 32, p. 1173-1181. Comments: This laboratory-rabbit-based study provides interesting insight into the histological, histochemical, structural, anatomical, and biomechanical changes that take place in a semitendinosus tendon (part of the hamstring group) that has been harvested as an ACL-graft source. The authors note that many of the attributes of the regenerated tendon, including attachment (insertion) point, cellular structure, physical characteristics, and presence of biochemical markers, are noticeably different from those what is found in an unaltered tendon.
Reconstruction of the anterior cruciate ligament: Single versus double-bundle multistranded hamstring tendons, N. Adachi et al.; Journal of Bone and Joint Surgery, British Edition; May 2004, Volume 86-B, pages 515-520. Comments: These authors found that, despite that theoretical advantages of double-bundle ACL grafting, no clinical (i.e. measured functionally in real, live people) advantages could be found. However, it should be kept in mind that the biomechanical nuances of the human knee are quite difficult to measure in practice. No surgeon can detect, using manual-manipulation testing (e.g. Lachmann drawer test or the mechanical equivalent, the KT-1000/2000 arthrometer), whether the actual knee motion is that of a single-bundle ACL graft or a double-bundle one. But over the lifetime of a person, the biomechanical differences between a knee with a natural ACL and a reconstructed one show themselves in terms of accelerated wear to articular cartilage and menisci in the rebuilt knee. Such cartilage wear means osteoarthritis. (Note: ACL-injury-history knees also harbour a certain amount of irreversible damage from the initial injury event. This includes the aftermath of bone bruising and meniscal tearing.) Keep in mind that double-bundle grafting brings technical problems: it makes far greater demands on the surgeon's skill...and regular single-bundle ACL grafting is already very difficult for a surgeon to master. Evidence of this can be found in the fact that misplaced bone tunnels (i.e. surgeon error) are still the major cause of ACL-grafting failure. A correctly installed single-bundle ACL graft is much better than a poorly done double-bundle graft! (This article is cross-listed under the Choosing and Knee Ligament Graft Section.)
Second-look arthroscopy of anterior cruciate ligament grafts with multistranded hamstring tendons, Yukiyoshi Toritsuka et al.; Arthroscopy: The Journal of Arthroscopic & Related Surgery; May 2004, Volume 20(3), pages 287-293. Comments: These authors set out to compare single-bundle with double-bundle ACL reconstruction techniques. They were unable to find any advantages of the latter, but note that more study is required to show that the theoretical advantages (i.e. better biomechanics because a double-bundle graft would better mimic the movement of a natural ACL) translate into immediately tangible benefits in the everyday clinical realm. The follow-up period ranged from 5 to 51 months (just over 4 years). Given that knee-ligament injuries bring lifelong consequences, it would be nice to see follow-up periods of 10 years, 20 years, or even longer...because these are the time-frames in which the standard ACL-injury-history sequelae (e.g. degenerative changes in the knee) tend to become increasingly apparent. And, it is over these time frames that the theoretical benefits of double-bundle ACL reconstruction are more likely to translate into improved knee longevity. (Of course, the theoretical benefits of double-bundle ACL grafting are only able to exert themselves if the surgeon is capable of handling the increased technical complexity that double-bundle grafting methods bring. Many surgeons today have a lot of problems correctly performing traditional single-bundle ACL grafts. Proof of this can be found in the fact that the single major cause of ACL-graft failure is still surgeon error.)
Interference Screw Fixation of Soft Tissue Grafts in Anterior Cruciate Ligament Reconstruction: Part 1 Effect of Tunnel Compaction by Serial Dilators Versus Extraction Drilling on the Initial Fixation Strength, Janne T. Nurmi et al.; The American Journal of Sports Medicine, Baltimore; March 2004, Vol 32, p. 411-417. Comments: This article deals with the AT (anterior tibialis) tendon graft, which is more commonly used in Europe/Scandinavia than in North America. Much of the points from this study apply to other soft-tissue grafts (such as the hamstring DLSTG graft). The authors found that serial dilation is not as good as standard extraction-type drilling. (This is a cadaver-type study.)
Interference Screw Fixation of Soft Tissue Grafts in Anterior Cruciate Ligament Reconstruction: Part 2 Effect of Preconditioning on Graft Tension During and After Screw Insertion, Janne T. Nurmi et al.; The American Journal of Sports Medicine, Baltimore; March 2004, Vol 32, p. 418-424. Comments: This article follows directly from Nurmi-AJSM-Mar04a.shtml. The authors found that preconditioning (often done with devices such as the Graftmaster board, in an attempt to eliminate the viscoelastic behaviour of graft tissue [hence the tendency of connective tissues to deform when subjected to sustained loadings]) is of little value.
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, Toshiyuki Tashiro et al.; American Journal of Sports Medicine, Baltimore; July 2003, Vol 31, p.522-529. Comments: This study, which looked at 85 patients (originally 90, but 5 dropped out due to graft failure), found that hamstring-group strength (particularly at deep flexion angles) is detrimentally affected by hamstring-graft harvesting. The authors performed both DLST (double-looped semitendinosus) and DLSTG (double-looped semitendinosus-and-gracilis) grafting, and they noted that harvesting only the semitendinosus (i.e. leaving the gracilis untouched) brings substantially less hamstring-group weakening. The authors conclude that the choice of graft should first be predicated on the types of activities the patient intends to return to. In this study, follow-up was limited to 18 months post-op. It would be interesting to compare the DLST patients the DLSTG ones over the long term.
For a penetratingly insightful medium-term comparison of the two most common autografting options, please see the July 2002 article A Five-Year Comparison of Patellar Tendon Versus Four-Strand Hamstring Tendon Autograft for Arthroscopic Reconstruction of the Anterior Cruciate Ligament, by Leo A. Pinczewski et al., in the Choosing a Knee-Ligament Graft Subsection.
Regeneration of the Semitendinosus Tendon after Its Use in Anterior Cruciate Ligament Reconstruction -- A Histologic Study of Three Cases, Andrea Ferretti et al.; American Journal of Sports Medicine, Baltimore; March 2002, Vol 30, p.204-207. Comments: This study provides excellent insight into the histological changes that occur in a semitendinosus tendon (part of the hamstring group) that has been harvested as an ACL-graft source. The harvested tendon does indeed regenerate to a considerable extent. However, the morphology, histology, and anatomical attributes (most notably the insertion point) are quite different from those of an unharvested tendon.
Rotational Muscle Strength of the Limb After Anterior Cruciate Ligament Reconstruction Using Semitendinosus and Gracilis Tendon, Hiroyuki Segawa et al.; Arthroscopy: The Journal of Arthroscopic and Related Surgery; Feb 2002, Vol 18/2, p.177-182. Comments: This article is a must-read for anyone who is contemplating (or who has undergone) ACL reconstruction via hamstring autografting. The first two paragraphs of the discussion are razor-sharp; if you are tight for time, at least be sure to read those two paragraphs.
Mechanical evaluation of soft-tissue interference screw in free tendon anterior-cruciate-ligament graft fixation, Durgesh G. Nagarkatti; The American Journal of Sports Medicine, Baltimore; Jan/Feb 2001, Vol 29/1, p. 67. Comments: This article discusses bioabsorbable interference screws, and compares hamstring-group-tendon (DLSTG) ACL-graft-anchorage methodologies with those used in the context of the traditional patellar-tendon autograft.
Graft fixation in cruciate ligament reconstruction, Jefferson C. Brand; The American Journal of Sports Medicine, Baltimore; Sep/Oct 2000, Vol 28/5, p. 761 This article discusses ACL-graft anchorage techniques.
Interference screw fixation strength of quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque, Jefferson C. Brand; The American Journal of Sports Medicine, Baltimore; Sep/Oct 2000, Vol 28/5, p. 705. Comments: This article discusses hamstring-graft anchorage devices. The imperative for good bone density and careful graft installation is made clear.
The Influence of Reverse-Thread Screw Femoral Fixation on Laxity Measurements After Anterior Cruciate Ligament Reconstruction With Hamstring Tendon, Timothy Musgrove; The American Journal of Sports Medicine, Baltimore; Sep/Oct 2000, Vol 28/5, p. 695. Comments: Musgrove looks at the effect of the threading direction of the interference screw, as used to anchor ACL grafts. During tightening of the screw, the graft tends to be rotated inside the femoral tunnel; for right knees, the net result is that the graft ends up at the front of the tunnel, hence ending up too loose. Using reverse-threaded screws alleviates the problem. Musgrove recommends that when right-ACL reconstruction with interference-screw anchorage is performed, a reverse-threaded screw be selected for use in the femoral tunnel. (Note that it is technically impossible for any ACL graft to perfectly replicate the natural multifascicular structure of the natural ACL; however, a well-placed, correctly-tensioned graft comes reasonably close.)
Internal and External Tibial Rotation Strength After Anterior Cruciate Ligament Reconstruction Using Ipsilateral Semitendinosus and Gracilis Tendon Autografts,Randall W. Viola et al.; The American Journal of Sports Medicine, Baltimore; July 2000, Vol 28/5, p. 552-555. Comments: This study confirms what would be expected from hamstring autografting: the stripping-out of substantial portions of the hamstring-group tendons (i.e. knee flexors) is not without extremely worrisome long-term consequences. At an average of 51 months post-op, Viola et al. found, using the Cybex-NORM dynamometer, that hamstring-graft harvesting resulted in persistent internal tibial-rotation weakness under all test conditions. Because the hamstring group is essential in protecting the ACL against injurious hyperextension and also against excessive anterior-drawer forcing, any loss in strength in this group is cause for serious concern. (Concerns are amplified in females, who tend to have proportionally weak hamstrings to begin with, and who tend to land jumps with inadequate knee flexion.)
For penetrating insight into the functional anatomy and biomechanics/kinematics of natural versus reconstructed ACLs, be sure to read the pair of current-concepts articles by F.H. Fu: Current Trends in Anterior Cruciate Ligament Reconstruction; Part 1: Biology and Biomechanics of Reconstruction, and Current Trends in Anterior Cruciate Ligament Reconstruction; Part 2: Operative Procedures and Clinical Correlations , in the ACL Reconstruction via Patellar-Tendon Autografting Subsection.
Evaluation of the single-incision arthroscopic technique for anterior cruciate ligament replacement: A study of tibial tunnel placement, intraoperative graft tension, and stability, Stephen M. Howell; The American Journal of Sports Medicine, Baltimore; May/June 1999, Vol 27/3, p. 284. Comments: This article discusses double-looped semitendinosus and gracilis (hamstring-group, DLSTG) tendon ACL grafting. The importance of proper (i.e. anatomically-correct, isometric) graft-tunnel placement, along with proper graft tension at installation, is noted.
Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts, Hugh E. Magen; The American Journal of Sports Medicine, Baltimore; Jan/Feb 1999, Vol 27/1, p. 35. Comments: This article discusses soft-tissue-type graft anchorage, as pertaining to hamstring-type (DLSTG) ACL grafts.
For insight into the treatment of combined ACL-MCL tearing injuries, please see Anterior cruciate ligament-medial collateral ligament injury: Nonoperative management of medial collateral ligament tears with anterior cruciate ligament reconstruction: A preliminary report, by Shelbourne and Porter, and also The Treatment of Acute Combined Ruptures of the Anterior Cruciate and Medial Ligaments of the Knee, by Noyes and Barber-Westin, in the Injuries Involving the MCL and Treatment Thereof Subsection.
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