In order to become a member of the initiative it is essential that the expert has either used the Quadriceps tenton autograft for Ligament reconstruction in surgical practice or/and has published papers on the subject.
Each application will be processed and answer will be given in the shortest time possible
Year of publishing 2022
Abstract Purpose: The purpose of this study was to evaluate three different methods of attachment of continuous loop suspensory cortical preparation of all soft tissue central quad tendon grafts compared to a bone block control for anterior cruciate ligament reconstruction on construct displacement and load to failure. Methods: Thirty-two cadaveric central quadriceps tendon (CQT) specimens were harvested, using three clinical techniques for graft fixation: cortical button alone (BTB EB), BTB cortical button with rip-stop suture (BTB RS), and continuous loop cortical button (BTB CL). A control group was also included that consisted of a bone block secured within testing clamps (BTB CON). Specimens were preloaded to 150 N. Tendons were then cyclically loaded between 50 N and 250 N for 1,000 cycles at .5 Hz. Displacement was measured at the point of fixation of the CQT after the 150 N preload, 250 N initial load and every 100th cycle. The specimens were loaded to failure after 1,000 cycles. Results: There was a significant increase in displacement from .32 ± .56 mm for the BTB CON to 1.91 ± 1.13 mm for the BTB RS (P = .014) and 3.85 ± 2.32 mm for the BTB CL condition (P = .023). There was no significant increase in displacement for BTB EB (P = .182). Failure occurred for all of the BTB CL and 62.5% of the BTB EB specimens within the first 50 cycles. Twenty-five percent of the BTB CON specimens and 12.5% BTB RS failed at ∼400 and 500 cycles, respectively. Similar failure loads were observed for the BTB CON and the BTB RS (446.4 ± 151.46 N vs 505.74 ± 131.41 N; P = .99) Failure testing was not feasible for the BTB CL and BTB EB preparation methods. Conclusion: In response to cyclic loading, the three all-soft tissue suspensory conditions experienced significantly greater displacement compared to the bone block controls. None of the soft-tissue conditions appeared superior when compared to each other. Clinical relevance: It remains unknown which method of soft-tissue suspensory provides optimal fixation. As these autografts become more common, it is essential to evaluate which fixation methods provide superior outcomes. Keywords: ACL; bone block; quadriceps tendon; soft tissue fixation. © 2022 The Authors.
Year of publishing 2022
Abstract PURPOSE OF THE STUDY We aimed to evaluate the biomechanical properties of quadriceps tendon graft with a bone plug ending (QTBP) and a quadriceps graft with a tendinous ending(QTT) fixed on the femoral side with different fixation devices. MATERIAL AND METHODS Twenty-five paired 2-year-old calf QTs and 25 paired 2-year-old sheep femurs were used for this study. 90x8 mm central part of the quadriceps tendons with or without a bone plug was harvested. 8×25 mm tunnel was placed in lateral condyles. The QTT was fixed with four different fixation devices, including the adjustable suspensory system (QTT-ASS, group 1), biodegradable interference screws (QTT-BIS, group 2), titanium interference screws (QTT-TIS, group 3), and an adjustable suspensory system + biodegradable interference screws (QTT-(ASS+BIS), group 4); QTBP was fixed with titanium interference screws (QTBP-TIS, group 5). All groups were tested in a servohydraulic materials testing machine. Stiffness(N/mm), slippage of the tendon(mm), and the ultimate tensile load-bearing ability(N) of the groups were tested. The Kruskal-Wallis H test was used with the Monte Carlo simulation technique to compare the nonparametric variables of stiffness, slippage, and ultimate tensile load. Dunn's test was used for the post hoc analyses. RESULTS Group 3 had the stiffest fixation (median 45.09 N/mm). The amount of slippage was highest in group 1(median 6.41mm). Group 1 was the most resistant group against a tensile load during the load-to-failure test(464 N). Fixing the QTT with the ASS and BIS in group 4 increased both stiffness and ultimate tensile load strength. There was no significant difference between the QTBP and QTT fixed with titanium screws. Fixing QTT with titanium screws was significantly superior to fixation with BIS(p < 0.05). CONCLUSIONS This study demonstrates that QTBP fixation with TIS have no advantage over QTT fixation with TIS on the femoral side. Although the QTT group fixed with ASS was the most resistant group against tensile forces during load-to-failure test, amount of slippage was highest for this group as well. Thus, if an ASS is to be used, a strong tension force must be applied prior to tibial side fixation to prevent further slippage of the graft in the tunnel. Key words: anterior cruciate ligament, quadriceps tendon graft, femoral side, fixation, biomechanical properties.
Year of publishing 2022
© 2021. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).
Year of publishing 2022
© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).
Year of publishing 00.00.0000
Year of publishing 2012
Abstract Purpose: A secure tibial press-fit technique in posterior cruciate ligament reconstructions is an interesting technique because no hardware is necessary. For anterior cruciate ligament (ACL) reconstruction, a few press-fit procedures have been published. Up to the present point, no biomechanical data exist for a tibial press-fit posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to characterize a press-fit procedure for PCL reconstruction that is biomechanically equivalent to an interference screw fixation. Methods: Quadriceps and hamstring tendons of 20 human cadavers (age: 49.2 ± 18.5 years) were used. A press-fit fixation with a knot in the semitendinosus tendon (K) and a quadriceps tendon bone block graft (Q) were compared to an interference screw fixation (I) in 30 porcine femora. In each group, nine constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness, and elongation during failure testing and cyclical loading were investigated. Results: The maximum load to failure was 518 ± 157 N (387-650 N) for the (K) group, 558 ± 119 N (466-650 N) for the (I) group, and 620 ± 102 N (541-699 N) for the (Q) group. The stiffness was 55 ± 27 N/mm (18-89 N/mm) for the (K) group, 117 ± 62 N/mm (69-165 N/mm) for the (I) group, and 65 ± 21 N/mm (49-82 N/mm) for the (Q) group. The stiffness of the (I) group was significantly larger (P = 0.01). The elongation during cyclical loading was significantly larger for all groups from the 1st to the 5th cycle compared to the elongation in between the 5th to the 20th cycle (P < 0.03). Conclusion: All techniques exhibited larger elongation during initial loading. Load to failure and stiffness was significantly different between the fixations. The Q fixation showed equal biomechanical properties compared to a pure tendon fixation (I) with an interference screw. All three fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical. Clinical trials have to investigate the biological effectiveness of these fixation techniques.
Year of publishing 2022
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Year of publishing 2022
© The Author(s) 2022.
Year of publishing 2022
© 2022. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.
Year of publishing 2000
The aim of the present study was to quantify the amount of antagonist coactivation and the resultant moment of force generated by the hamstring muscles during maximal quadriceps contraction in slow isokinetic knee extension. The net joint moment at the knee joint and electromyographic (EMG) signals of the vastus medialis, vastus lateralis, rectus femoris muscles (quadriceps) and the biceps femoris caput longum and semitendinosus muscles (hamstrings) were obtained in 16 male subjects during maximal isokinetic knee joint extension (KinCom, ROM 90-10 degrees, 30 degrees x s(-1)). Two types of extension were performed: [1] maximal concentric quadriceps contractions and [2] maximal eccentric hamstring contractions Hamstring antagonist EMG in [1] were converted into antagonist moment based on the EMG-moment relationships determined in [2] and vice versa. Since antagonist muscle coactivation was present in both [1] and [2] a set of related equations was constructed to yield the moment/EMG relationships for the hamstring and quadriceps muscles, respectively. The equations were solved separately for every 0.05 degrees knee joint angle in the 90-10 degrees range of excursion (0 degrees = full extension) ensuring that the specificity of muscle length and internal muscle lever arms were incorporated into the moment/EMG relationships established. Substantial hamstring coactivation was observed during quadriceps agonist contraction. This resulted in a constant level of antagonist hamstring moment of about 30 Nm throughout the range of motion. In the range of 30-10 degrees from full knee extension this antagonist hamstring moment corresponded to 30-75% of the measured knee extensor moment. The level of antagonist coactivation was 3-fold higher for the lateral (Bfcl) compared to medial (ST) hamstring muscles The amount of EMG crosstalk between agonist-antagonist muscle pairs was negligible (Rxy2<0.02-0.06). The present data show that substantial antagonist coactivation of the hamstring muscles may be present during slow isokinetic knee extension. In consequence substantial antagonist flexor moments are generated. The antagonist hamstring moments potentially counteract the anterior tibial shear and excessive internal tibial rotation induced by the contractile forces of the quadriceps near full knee extension. In doing so the hamstring coactivation is suggested to assist the mechanical and neurosensory functions of the anterior cruciate ligament (ACL).
Year of publishing 2012
Introduction: Coactivation of the hamstring muscles during dynamic knee extension may compensate for increased knee joint laxity in anterior cruciate ligament (ACL) deficient subjects. This study examined if antagonist muscle coactivation during maximal dynamic knee extension was elevated in subjects with anterior cruciate ligament (ACL) deficiency compared to age-matched healthy controls. Methods: Electromyography (EMG) and net knee joint moments were recorded during maximal concentric quadriceps and eccentric hamstring contractions, performed in an isokinetic dynamometer (ROM: 90-10°, angular speed: 30°/s). Hamstring antagonist EMG recorded during concentric quadriceps contraction was converted into antagonist moment based on the EMG-moment relationship observed during eccentric agonist contractions. Results: The magnitude of antagonist hamstring EMG was 65.5% higher in ACL deficient subjects compared to healthy controls (p<0.05). Likewise, antagonist hamstring moment expressed in percentage of the measured net extension moment was elevated in ACL deficient subjects (56 ± 8 to 30 ± 6%) compared to controls (36 ± 5 to 19 ± 2%) at 20-50° of knee flexion (0°=full extension) (p<0.05). Discussion: The results showed a marked increase in hamstring coactivation towards more extended joint positions. Notably, this progressive rise in coactivation was greater in ACL deficient subjects, which may reflect a compensatory strategy to provide stability to the knee joint in the anterior-posterior plane during isolated knee extension. The present study encourages further investigations of hamstring coactivation in ACL deficient subjects.
Year of publishing 2000
Purpose: The purpose of this study was to use current fixation techniques and compare the stiffness and ultimate tensile failure of the tendinous end of the quadriceps tendon (QT) with the bone plug end of the bone-patellar tendon-bone (BPTB) graft using current techniques of fixation. Type of study: Randomized trial of elderly cadaver knees. Materials and methods: Tibial and femoral biodegradable interference fixation and femoral EndoButton (Smith & Nephew, Acufex, Mansfield, MA) fixation in bone tunnels with the QT and the BPTB graft were compared by using 10 pairs of elderly cadavers and biomechanical testing. Two groups, fixation at time zero (simulating fixation in the operating room) and testing after 1, 000 loading cycles (simulating patient rehabilitation exercises), were used. Results: At time zero fixation, stiffness of the soft tissue QT tibial tunnel interference fixation was 59% less stiff than the stiffness of the interference fixation of a BPTB plug in a femoral tunnel (P =.11). The EndoButton femoral fixation resulted in a decrease in stiffness at time zero compared with femoral tunnel interference fixation of the soft tissue QT (P =.03). All groups improved stiffness with cycling the construct to 1,000 cycles. Conclusions: Placement of the QT tendinous end of the graft in the femoral bone tunnel when using a interference fixation will approximate the stiffness of a bone plug in the tibial bone tunnel with interference fixation. The EndoButton fixation is not as stiff as either of the femoral interference fixation options. The addition of more than 20 loading cycles could remove laxity from the graft fixation-graft cruciate ligament complex and improve its stiffness.
Year of publishing 2006
Introduction: Press-fit fixation of bone-patellar tendon-bone (BPTB) grafts in anterior cruciate ligament (ACL) reconstruction has been analyzed biomechanically in previous studies; however, the use of quadriceps tendon-patellar bone (QTPB) grafts has not been studied so far. It is hypothesized that QTPB grafts provide primary fixation strength comparable to BPTB grafts in press-fit ACL reconstruction with respect to bone plug length and loading angle. Materials and methods: Fifty-two QTPB grafts were harvested from fresh human cadaver knees (mean age 73.3 years) with the length of the patellar bone plug being either 15 mm (Group I) or 25 mm (Group II). The grafts were anchored within fresh porcine femora (mean age 12 months) using a press-fit fixation technique. Forty-eight specimens were loaded to failure at 10 mm/s with varying loading angles of 0 degrees , 30 degrees , and 60 degrees until failure. A microradiographic pre-post-implantation analysis was conducted on four grafts. Results: The biomechanical testing showed a significant difference in the ultimate failure loads comparing Group I (mean 224+/-79.3 N) to Group II (mean 339+/-61.4 N), both showing mean ultimate failure loads to increase with rising loading angle. The predominant mode of failure was graft pullout at axial loading and tendon rupture at 60 degrees loading angle. The microradiographic analysis revealed an iatrogenic damage of the bone-tendon junction on the cancellous aspect of the bone plug in all trials, corresponding with the site of impactor placement during implantation. Conclusion: QTPB grafts provide a loading capability comparable to BPTB grafts in press-fit ACL reconstruction. The broad and profound area of quadriceps tendon attachment to the patellar bone plug makes graft implantation demanding.
Year of publishing 2017
Year of publishing 2015
Year of publishing 2014
Purpose: Quadriceps tendon grafts have renewed interest for ACL reconstruction; however, biomechanical studies comparing anatomic single-bundle (SB) and double-bundle (DB) reconstruction techniques are rare. The purpose of this study was to compare the knee biomechanics in four different types of anatomic ACL reconstruction techniques, using the quadriceps tendon in a human cadaver. Methods: Four different tibial (T) and femoral (F) tunnel configurations, (a) DB-2F-2T, (b) DB-2F-1T, (c) SB-1F-1T and (d) DB-1F-2T, were used for ACL reconstruction using the split quadriceps tendon with patella bone. Ten cadaver knees were subjected to an 89 N anterior tibial load and combined 7 N m valgus and 5 N m internal torques. The anterior tibial translation (ATT) and in situ force were measured using a robotic system for the ACL-intact, ACL-deficient and ACL-reconstructed knees. Results: DB reconstructions mostly restored ATT to the intact ACL. The in situ forces under the anterior load in the DB reconstructions were similar to the intact ACL, but that of the SB reconstruction was different at 30°, 60° and 90° of flexion (P < 0.05). Under combined torques, the in situ force of the SB graft was less than that of intact ACL at 0°, 15° and 30° of knee flexion (P < 0.05), while that of the ACL DB reconstruction was similar to the intact ACL. Conclusion: DB ACL reconstruction using quadriceps tendon can restore biomechanics of the knee to that of the intact ACL regardless of whether three or four tunnels are used, but SB reconstruction does not.
Year of publishing 2017
Year of publishing 2014
Year of publishing 2016
Purpose: To quantify the structural and material properties of 10-mm central sections of the quadriceps and patellar tendons in the setting of anterior cruciate ligament reconstruction using cadaveric grafts and biomechanical analysis. Methods: The structural and mechanical properties of 11 bone-patellar tendon-bone (BPTB) and 12 quadriceps tendon-bone (QT) allografts were evaluated. Ten-millimeter-wide tendon grafts from both patellar and quadriceps tendons were harvested and subjected to biomechanical testing using the MTS servohydraulic test machine (MTS Systems, Eden Prairie, MN). The cross-sectional area was also calculated and compared between the BPTB and QT grafts. Results: The mean cross-sectional area was 91.2 ± 10 mm(2) for the QT compared with 48.4 ± 8 mm(2) for the BPTB (P = .005). The mean ultimate stress was 23.9 ± 7.4 MPa for the QT and 33.4 ± 9.0 MPa for the BPTB (P = .01). Ultimate strain was similar between the 2 tested groups, with a 10.7% change in the QT group and an 11.4% change in the BPTB group (P = .484). The Young modulus of elasticity was 255.3 ± 64.1 MPa for the QT and 337.8. ± 67.7 MPa for the BPTB (P = .006). The mean stiffness was 466.2 ± 133 N/mm for the QT and 278.0 ± 75 N/mm for the BPTB (P = .005). The mean ultimate load to failure was 2,185.9 ± 758.8 N for the QT compared with 1,580.6 ± 479.4 N for the BPTB (P = .045). Conclusions: The cross-sectional area of the QT was nearly twice that of the BPTB. Ultimate load to failure and stiffness were also significantly higher for the QT graft. The variability in the cross-sectional area was similar in both tendon groups. Clinical relevance: On the basis of graft predictability and biomechanical properties, our study reaffirms that the QT graft is a biomechanically sound alternative for anterior cruciate ligament reconstruction.
Year of publishing 2016
Year of publishing 2015
Purpose: Quadriceps tendon grafts have renewed interest for ACL reconstruction; however, biomechanical studies comparing anatomic single-bundle (SB) and double-bundle (DB) reconstruction techniques are rare. The purpose of this study was to compare the knee biomechanics in four different types of anatomic ACL reconstruction techniques, using the quadriceps tendon in a human cadaver. Methods: Four different tibial (T) and femoral (F) tunnel configurations, (a) DB-2F-2T, (b) DB-2F-1T, (c) SB-1F-1T and (d) DB-1F-2T, were used for ACL reconstruction using the split quadriceps tendon with patella bone. Ten cadaver knees were subjected to an 89 N anterior tibial load and combined 7 N m valgus and 5 N m internal torques. The anterior tibial translation (ATT) and in situ force were measured using a robotic system for the ACL-intact, ACL-deficient and ACL-reconstructed knees. Results: DB reconstructions mostly restored ATT to the intact ACL. The in situ forces under the anterior load in the DB reconstructions were similar to the intact ACL, but that of the SB reconstruction was different at 30°, 60° and 90° of flexion (P < 0.05). Under combined torques, the in situ force of the SB graft was less than that of intact ACL at 0°, 15° and 30° of knee flexion (P < 0.05), while that of the ACL DB reconstruction was similar to the intact ACL. Conclusion: DB ACL reconstruction using quadriceps tendon can restore biomechanics of the knee to that of the intact ACL regardless of whether three or four tunnels are used, but SB reconstruction does not.
Year of publishing 2015
Year of publishing 2015
Background: Bone tunnel enlargement is a phenomenon present in all anterior cruciate ligament (ACL)- reconstruction techniques. It was hypothesized that press-fit fixation using a free autograft bone plug reduces the overall tunnel size in the tibial tunnel. Methods: In a prospective cohort study twelve patients who underwent primary ACL reconstruction using an autologous quadriceps tendon graft and adding a free bone block for press-fit fixation (PF) in the tibial tunnel were matched to twelve patients who underwent ACL reconstruction with a hamstring graft and interference screw fixation (IF). The diameters of the bone tunnels were analysed by a multiplanar reconstruction technique (MPR) in a CT scan three months postoperatively. Manual and instrumental laxity (Lachman test, Pivot-shift test, Rolimeter) and functional outcome scores (International Knee Documentation Committee sore, Tegner activity level) were measured after one year follow up. Results: In the PF group the mean bone tunnel diameter at the level of the joint entrance was not significantly enlarged. One and two centimeter distal to the bone tunnel diameter was reduced by 15% (p = .001). In the IF group the bone tunnel at the level of the joint entrance was enlarged by 14% (p = .001). One and two centimeter distal to the joint line the IF group showed a widening of the bone tunnel by 21% (p < .001) One and two centimeter below the joint line the bone tunnel was smaller in the PF group when compared to the IF group (p < .001). No significant difference for laxity test and functional outcome scores could be shown. Conclusion: This study demonstrates that press-fit fixation with free autologous bone plugs in the tibial tunnel results in significantly smaller diameter of the tibial tunnel compared to interference screw fixation.
Year of publishing 2014
Year of publishing 2014
Quadriceps tendon with a patellar bone block may be a viable alternative to Achilles tendon for anterior cruciate ligament reconstruction (ACL-R) if it is, at a minimum, a biomechanically equivalent graft. The objective of this study was to directly compare the biomechanical properties of quadriceps tendon and Achilles tendon allografts. Quadriceps and Achilles tendon pairs from nine research-consented donors were tested. All specimens were processed to reduce bioburden and terminally sterilized by gamma irradiation. Specimens were subjected to a three phase uniaxial tension test performed in a custom environmental chamber to maintain the specimens at a physiologic temperature (37 ± 2 °C) and misted with a 0.9 % NaCl solution. There were no statistical differences in seven of eight structural and mechanical between the two tendon types. Quadriceps tendons exhibited a significantly higher displacement at maximum load and significantly lower stiffness than Achilles tendons. The results of this study indicated a biomechanical equivalence of aseptically processed, terminally sterilized quadriceps tendon grafts with bone block to Achilles tendon grafts with bone block. The significantly higher displacement at maximum load, and lower stiffness observed for quadriceps tendons may be related to the failure mode. Achilles tendons had a higher bone avulsion rate than quadriceps tendons (86 % compared to 12 %, respectively). This was likely due to observed differences in bone block density between the two tendon types. This research supports the use of quadriceps tendon allografts in lieu of Achilles tendon allografts for ACL-R.
Year of publishing 2014
Implant-free anterior cruciate ligament (ACL) reconstruction is the fixation of ACL grafts without the need for artificial implants. Our aim was to study the evolution of this technique, review the biomechanical evidence and summarise the results. Implant-free graft fixation for bone patella tendon ACL reconstruction was first described in 1987. This concept of implant-free graft fixation was adapted for hamstring and quadriceps tendons as alternative graft sources. Various biomechanical studies have reported that by adhering to certain technical details, this technique provides comparable fixation strength as conventional ACL fixation. The outcome studies of implant-free ACL reconstruction also report clinical results similar to ACL reconstruction with conventional implants.
Year of publishing 2013
Purpose: The purposes of this study were to investigate anterior tibial translation under loading conditions after single-bundle (SB) anterior cruciate ligament (ACL) reconstruction using a rectangular tunnel placement strategy with quadriceps and bone--patellar tendon--bone (BPTB) graft and to compare these data with a SB hamstring reconstruction with a round tunnel design. Methods: In 9 human cadaveric knees, the knee kinematics were examined with robotic/universal force-moment sensor testing. Within the same specimen, the knee kinematics under simulated pivot-shift and KT-1000 arthrometer (MEDmetric, San Diego, CA) testing were determined at 0°, 15°, 30°, 60°, and 90° of flexion under different conditions: intact knee, ACL-deficient knee, and SB ACL-reconstructed knee. For the SB ACL-reconstructed knee, 3 different SB reconstruction techniques were used: a rectangular tunnel strategy (9 × 5 mm) with quadriceps graft, a rectangular tunnel strategy with BPTB graft, and a round tunnel strategy (7 mm) with hamstring graft. Results: In a simulated Lachman test, a statistically significant difference was found at 0° and 15° of knee flexion between the rectangular reconstruction with quadriceps graft (5.1 ± 1.2 mm and 8.3 ± 2 mm, respectively) or BPTB graft (5.3 ± 1.5 mm and 8 ± 1.9 mm, respectively) and the reconstruction using hamstring graft (7.2 ± 1.4 mm and 12 ± 1.8 mm, respectively) (P = .032 and P = .033, respectively, at 0°; P = .023 and P = .02, respectively, at 15°). On the simulated pivot-shift test at 0° and 15°, rectangular ACL reconstruction with quadriceps graft (3.9 ± 2.1 mm and 6.5 ± 1.7 mm, respectively) or BPTB graft (4.2 ± 1.8 mm and 6.7 ± 1.7 mm, respectively) showed a significantly lower anterior tibial translation when compared with round tunnel reconstruction (5.5 ± 2.1 mm and 7.9 ± 1.9 mm, respectively) (P = .03 and P = .041, respectively, at 0°; P = .042 and P = .046, respectively, at 15°). Conclusions: Under simulated Lachman testing and pivot-shift testing, a reconstruction technique using a rectangular tunnel results in significantly lower anterior tibial translation at 0° and 15° of flexion in comparison to knees reconstructed with a hamstring SB graft using a round tunnel strategy. Clinical relevance: ACL reconstruction with a rectangular tunnel and BPTB and quadriceps tendon might result in better anterior knee stability at low flexion angles than ACL reconstruction with hamstring SB graft and a round tunnel in the clinical setting.
Year of publishing 2011
Purpose: Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations. Methods: In a controlled laboratory study, the patellar-, quadriceps- and hamstring tendons of 10 human cadavers (age: 49.2 ± 18.5 years) were used. An inside out press-fit fixation with a knot in the semitendinosus and gracilis tendons (SG) combined with an additional bone block, with two quadriceps tendon bone block grafts (QU) was compared with press-fit fixation of two bone patellar tendon bone block (PT) grafts in 30 porcine femora. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated. Results: The maximum load to failure was 703 ± 136 N for SG fixation, 632 ± 130 N for QU and 656 ± 127 N for PT fixation. Stiffness of the constructs averaged 138 ± 26 N/mm for SG, 159 ± 74 N/mm for QU, and 154 ± 50 N/mm for PT fixation. Elongation during initial cyclical loading was 1.2 ± 1.4 mm for SG, 2.0 ± 1.4 mm for QU, and 1.0 ± 0.6 mm for PT (significantly larger for PT and QU between the first 5 cycles compared with cycles 15-20th, P < 0.01). Conclusion: All investigated double-bundle fixation techniques were equal in terms of maximum load to failure, stiffness, and elongation. Unlike with single-bundle press-fit fixation techniques that have been published, no difference was observed between pure tendon combined with an additional bone block and tendon bone grafts. All techniques exhibited larger elongation during initial cyclical loading. All three press-fit fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical.
Year of publishing 2010
Sixty-eight patients were clinically evaluated preoperatively, 3, 5, 7, 9 months, 1 and 2 years after ACL reconstruction, 34 with patellar tendon graft, 34 with hamstring graft. Outcome regarding graft choice and anterior knee laxity (P = 0.04) was in favour of patellar tendon graft. Hamstring graft led to a larger laxity, 2.4 mm compared with patellar tendon graft, 1.3 mm at 1 year and 2.5 mm and 1.5 mm, respectively, at 2 years (P = 0.05). There was a significant difference in rotational knee stability in favour of the patellar tendon graft at all test occasions but 9 months. A general effect regarding graft choice and muscle torque was found at 90 degrees/s for quadriceps (P = 0.03) and hamstrings (P < or = 0.0001) and at 230 degrees/s for hamstrings (P < or = 0.0001). No treatment effect regarding graft choice and one-leg hop test, postural sway or knee function was found. No group differences in anterior knee pain were found at any of the test occasions but 2 years in favour of hamstring graft compared to patellar tendon graft (P = 0.04). Patellar tendon graft resulted in higher activity level than hamstring graft at all test occasions but 1 year (P = 0.01). Patellar tendon ACL reconstruction led to more stable knees with less anterior knee laxity and less rotational instability than hamstring ACL reconstruction. Hamstring graft patients had not reached preoperative level in hamstring torque even 2 years after ACL reconstruction. Athletes with patellar tendon graft returned to sports earlier and at a higher level than those with hamstring graft.
Year of publishing 2009
Background: Anatomic double-bundle reconstruction has been thought to better simulate the anterior cruciate ligament anatomy. It is, however, a technically challenging procedure, associated with longer operation time and higher cost. Hypothesis: Double-bundle anterior cruciate ligament reconstruction using a single femoral and tibial tunnel can closely reproduce intact knee kinematics. Study design: Controlled laboratory study. Methods: Eight fresh-frozen human cadaveric knee specimens were tested using a robotic testing system to investigate the kinematic response of the knee joint under an anterior tibial load (130 N), simulated quadriceps load (400 N), and combined torques (5 N.m valgus and 5 N.m internal tibial torques) at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion. Each knee was tested sequentially under 4 conditions: (1) anterior cruciate ligament intact, (2) anterior cruciate ligament deficient, (3) single-bundle anterior cruciate ligament reconstruction using quadrupled hamstring tendon, and (4) single-tunnel-double-bundle anterior cruciate ligament reconstruction using the same tunnels and quadrupled hamstring tendon graft as in the single-bundle anterior cruciate ligament reconstruction. Results: Single-tunnel-double-bundle anterior cruciate ligament reconstruction more closely restored the intact knee kinematics than single-bundle anterior cruciate ligament reconstruction at low flexion angles (< or =30 degrees ) under the anterior tibial load and simulated muscle load (P < .05). However, single-tunnel-double-bundle anterior cruciate ligament reconstruction overconstrained the knee joint at high flexion angles (> or =60 degrees ) under the anterior tibial load and at 0 degrees and 30 degrees of flexion under combined torques. Conclusion: This double-bundle anterior cruciate ligament reconstruction using a single tunnel can better restore anterior tibial translations to the intact level compared with single-bundle anterior cruciate ligament reconstruction at low flexion angles, but it overconstrained the knee joint at high flexion angles. Clinical relevance: This technique could be an alternative for both single-bundle and double-tunnel-double-bundle anterior cruciate ligament reconstructions to reproduce intact knee kinematics and native anterior cruciate ligament anatomy.
Year of publishing 2008
Ligaments and tendons are similar in composition but differ in proportion and arrangement. Tendons are being used as grafts for the ACL reconstruction. Their microscopic structure has not been sufficiently studied and compared to the native ACL. A null hypothesis was declared stating that the anterior cruciate ligament should be histological, morphologically and functionally different from the tendon grafts used for ACL reconstruction. We investigated similarities and differences of the structure of ACL and tendons used as a graft tissue for ACL reconstruction. In this study, standardized samples of quadriceps, hamstrings (semitendinosus and gracilis) and patellar tendons, and the ACL were harvested from 26 autopsies (average age 36.4) and were investigated using light and electron microscopy, immunohistochemistry and morphometry. The thickness of the collagen fibrils, collagen organization and diameter, the fibril/interstitium ratio, density of fibroblasts and blood vessels, and distribution of the collagen type I, III and V fibrils were analyzed. The semitendinosus showed the highest density of fibroblasts and blood vessels, while the gracilis the highest fibril/interstitium ratio. No differences regarding the thickness of collagen fibrils and distribution of fibrils were found. The ACL had the highest concentration of type III and V collagen fibrils as well as elastic fibers. The histological and ultrastructural appearance of the ACL differs from those of the tendons used as graft, for ACL reconstruction. Its ultrastructure is varied and complex, with its collagen fibers bundles lying in many directions.
Year of publishing 2007
Purpose: This retrospective study was performed to relate tunnel position as measured by plain radiographs and magnetic resonance imaging (MRI) to residual pivot shift and to determine its clinical relevance after anterior cruciate ligament reconstruction via central quadriceps tendon autograft. Methods: We reviewed 137 arthroscopic anterior cruciate ligament reconstructions via quadriceps tendon autograft with a minimum of 2 years' follow-up. Clinical results were evaluated by use of the Lachman test, pivot-shift test, Lysholm score, and Cybex dynamometer (Lumex, Ronkonkoma, NY). Anterior tibial translation was measured with the KT-1000 arthrometer (MEDmetric, San Diego, CA). Patients were classified into 3 groups based on postoperative pivot-shift and Lachman test findings: group I, both negative; group II, negative Lachman test and positive pivot shift; and group III, both positive. The radiographic analysis was performed via the angle between the tibial and femoral tunnels on plain anteroposterior radiographs, the angle between the tibial tunnel and anterior tibial cortex on the lateral view, and the femoral and tibial tunnel location by use of the ratio method. Postoperative knee MRI was performed, and the angle between the intercondylar anteroposterior axis and femoral tunnel on the axial view and the angle between the joint line and the graft on the oblique coronal and sagittal views were measured. Results: There were 100 patients in group I, 13 in group II, and 24 in group III. Patients in group I showed the greatest improvement in Lysholm score among the groups, and patients in group III had the greatest side-to-side difference by KT-1000 arthrometer. Tunnel obliquity as measured by the angle between the anteroposterior axis of the femur and the femoral tunnel in the axial view on MRI was greater (P < .05) and the angle between the joint line and the graft on the oblique coronal view was less in group I. Conclusions: This study showed a significantly lower Lysholm score and more vertical orientation of the femoral tunnel in the group with residual pivot shift than in the group without pivot shift. Vertical orientation of the femoral tunnel in the axial plane is closely related to residual pivot shift without definite anteroposterior laxity. More oblique positioning of the graft may have advantages in rotational stability, which in turn increase subjective patient satisfaction. Level of evidence: Level III, diagnostic study of nonconsecutive patients without consistently applied reference gold standard.
Year of publishing 2007
Background: Recently, the use of the quadriceps tendon transplant with bone block (patellar bone quadriceps tendon autografts) for anterior cruciate ligament reconstruction has increasingly been reported. Hypothesis: Clinical results after the implantation of a patellar bone quadriceps tendon autograft fixed with cross-pins or screws will show no significant difference between the 2 techniques with regard to stability, function, and subjective satisfaction. Study design: Cohort study; Level of evidence, 2. Methods: Between 1998 and 2004, 193 patients with anterior cruciate ligament ruptures were implanted with a patellar bone quadriceps tendon autograft. For 100 of these patients, fixation was carried out using absorbable cross-pins, and for the remaining 93, fixation was carried out using absorbable screws. The results were evaluated by means of International Knee Documentation Committee, Noyes, and Lysholm scores, as well as KT-1000 arthrometer measurement and subjective satisfaction. Results: The mean follow-up postoperative control period was 29 months. In the International Knee Documentation Committee overall evaluation, the pin group showed a significantly better result (P =.03). The values of the Noyes score produced no significant differences. The mean value of the Lysholm score was 94 points in the screw group and 89 points in the pin group (P <.001). Overall, 90% of the patients subjectively judged their conditions as good or very good. Conclusion: With both operating processes examined, 80% to 90% of the cases achieved good to very good results. The use of cross-pins can be recommended for fixing patellar bone quadriceps tendon autografts.
Year of publishing 2006
Introduction: Press-fit fixation of bone-patellar tendon-bone (BPTB) grafts in anterior cruciate ligament (ACL) reconstruction has been analyzed biomechanically in previous studies; however, the use of quadriceps tendon-patellar bone (QTPB) grafts has not been studied so far. It is hypothesized that QTPB grafts provide primary fixation strength comparable to BPTB grafts in press-fit ACL reconstruction with respect to bone plug length and loading angle. Materials and methods: Fifty-two QTPB grafts were harvested from fresh human cadaver knees (mean age 73.3 years) with the length of the patellar bone plug being either 15 mm (Group I) or 25 mm (Group II). The grafts were anchored within fresh porcine femora (mean age 12 months) using a press-fit fixation technique. Forty-eight specimens were loaded to failure at 10 mm/s with varying loading angles of 0 degrees , 30 degrees , and 60 degrees until failure. A microradiographic pre-post-implantation analysis was conducted on four grafts. Results: The biomechanical testing showed a significant difference in the ultimate failure loads comparing Group I (mean 224+/-79.3 N) to Group II (mean 339+/-61.4 N), both showing mean ultimate failure loads to increase with rising loading angle. The predominant mode of failure was graft pullout at axial loading and tendon rupture at 60 degrees loading angle. The microradiographic analysis revealed an iatrogenic damage of the bone-tendon junction on the cancellous aspect of the bone plug in all trials, corresponding with the site of impactor placement during implantation. Conclusion: QTPB grafts provide a loading capability comparable to BPTB grafts in press-fit ACL reconstruction. The broad and profound area of quadriceps tendon attachment to the patellar bone plug makes graft implantation demanding.
Year of publishing 2000
Purpose: The purpose of this study was to use current fixation techniques and compare the stiffness and ultimate tensile failure of the tendinous end of the quadriceps tendon (QT) with the bone plug end of the bone-patellar tendon-bone (BPTB) graft using current techniques of fixation. Type of study: Randomized trial of elderly cadaver knees. Materials and methods: Tibial and femoral biodegradable interference fixation and femoral EndoButton (Smith & Nephew, Acufex, Mansfield, MA) fixation in bone tunnels with the QT and the BPTB graft were compared by using 10 pairs of elderly cadavers and biomechanical testing. Two groups, fixation at time zero (simulating fixation in the operating room) and testing after 1, 000 loading cycles (simulating patient rehabilitation exercises), were used. Results: At time zero fixation, stiffness of the soft tissue QT tibial tunnel interference fixation was 59% less stiff than the stiffness of the interference fixation of a BPTB plug in a femoral tunnel (P =.11). The EndoButton femoral fixation resulted in a decrease in stiffness at time zero compared with femoral tunnel interference fixation of the soft tissue QT (P =.03). All groups improved stiffness with cycling the construct to 1,000 cycles. Conclusions: Placement of the QT tendinous end of the graft in the femoral bone tunnel when using a interference fixation will approximate the stiffness of a bone plug in the tibial bone tunnel with interference fixation. The EndoButton fixation is not as stiff as either of the femoral interference fixation options. The addition of more than 20 loading cycles could remove laxity from the graft fixation-graft cruciate ligament complex and improve its stiffness.
Year of publishing 1999
We analyzed mechanical tensile properties of 16 10-mm wide, full-thickness central parts of quadriceps tendons and patellar ligaments from paired knees of eight male donors (mean age, 24.9 years). Uniaxial tensile testing was performed in servohydraulic materials testing machine at an extension rate of 1 mm/sec. Sixteen specimens were tested unconditioned and 16 specimens were tested after cyclic preconditioning (200 cycles between 50 N and 800 N at 0.5 Hz). Mean cross-sectional areas measured 64.6 +/- 8.4 mm2 for seven unconditioned and 61.9 +/- 9.0 mm2 for eight preconditioned quadriceps tendons and were significantly larger than those values of seven unconditioned and seven preconditioned patellar ligaments (36.8 +/- 5.7 mm2 and 34.5 +/- 4.4 mm2, respectively). Mean ultimate tensile stress values of unconditioned patellar ligaments were significantly larger than those values of unconditioned quadriceps tendons: 53.4 +/- 7.2 N/mm2 and 33.6 +/- 8.1 N/mm2, respectively. Strain at failure was 14.4% +/- 3.3% for preconditioned patellar ligaments and 11.2% +/- 2.2% for preconditioned quadriceps tendons (P = 0.0428). Preconditioned patellar ligaments exhibited significantly higher elastic modulus than preconditioned quadriceps tendons. Based on mechanical tensile properties analyses, the quadriceps tendon-bone construct may represent a versatile alternative graft in primary and revision anterior and posterior cruciate ligament reconstruction.
Become a member