Anatomic double-bundle anterior cruciate ligament reconstruction: kinematics and knee flexion angle-graft tension relation

Short-Term Evaluation of Bone-ACL-Bone Complex Allograft in ACL Reconstruction in a Rabbit Model

The study is to evaluate incorporation of a bone-anterior cruciate ligament-bone (B-ACL-B) allograft in anterior cruciate ligament (ACL) reconstruction in a rabbit model. A total of 61 New Zealand white rabbits were used, with 23 donor rabbits for harvesting B-ACL-B allografts and 38 recipient rabbits undergoing unilateral ACL reconstruction with B-ACL-B allograft. Animals were euthanized for biomechanical testing, micro-computed tomography examination, histological analysis, multi-photon microscopy and transmission electron microscopy testing at 2, 4 and 8 weeks after surgery. Gross inspection and radiographs confirmed the intact ACL allograft in the proper anatomic position. Progressive healing occurred between the bone block and the bone tunnel as demonstrated by a gradual increase in average bone volume fraction and total mineral density at 4 and 8 weeks. Histological analysis showed new bone formation at the bone block-tunnel interface, with maintenance of the native ACL enthesis. Ultrastructural analysis demonstrated the maintenance of overall collagen matrix alignment, while there was repopulation with smaller diameter collagen fibrils. There was no significant difference between 4 and 8 weeks in mean failure force (p = 0.39) or stiffness (p = 0.15) for the B-ACL-B allografts. This study demonstrates the restoration of the normal anatomy of the ACL and progressive graft incorporation and remodeling using a B-ACL-B allograft for ACL reconstruction in the rabbit knee.

Bone-ACL-bone allograft for anterior cruciate ligament reconstruction: Short-term evaluation in a rabbit model with microcomputed tomography

The standard grafts used for anterior cruciate ligament (ACL) reconstruction are tendon, either patellar tendon, hamstring, or quadriceps. However, the microstructure and composition of tendon differs from ligament. Ideally, the ACL would be replaced with the same tissue. To evaluate the incorporation of a bone-ACL-bone (B-ACL-B) graft for ACL reconstruction, we performed a controlled laboratory study in a rabbit model with microcomputed tomography (μCT). Forty-six New Zealand white rabbits were used, with 17 donor rabbits to harvest bilateral B-ACL-B allografts and 29 rabbits undergoing unilateral ACL reconstruction with B-ACL-B allograft. Knee specimens were collected for biomechanical testing (n = 14) at 4 and 8 weeks and for μCT analysis (n = 15) at 2, 4, and 8 weeks after surgery. Gross inspection and μCT examination confirmed bone blocks in the appropriate anatomic position. Biomechanical tests revealed no difference in mean load-to-failure force for B-ACL-B allografts between 4 and 8 weeks. Progressive healing occurred between the bone block and the tunnel as demonstrated by a gradual increase on average bone-volume fraction and total mineral density (TMD) in both femoral and tibial tunnels. Remodeling of the bone block was evidenced by a significant decrease in TMD of both tibial and femoral bone blocks. This is a report of a novel rabbit B-ACL-B allograft reconstruction model demonstrating early signs of graft remodeling and incorporation. Clinical Relevance: This study demonstrates ACL reconstruction using an anatomically matched ACL allograft, rather than a tendon graft, may be possible based on early findings in this lapine model.

Editorial Commentary: For Single-Bundle Anterior Cruciate Ligament Reconstruction, Graft Fixation Should Be Performed at a Medium Tension in Full Extension: Multiple Bundle Reconstruction May Require a Different Strategy

Successful anterior cruciate ligament reconstruction requires a multifaceted approach to replicate normal knee anatomy and biomechanics. Graft tensioning force and the angle at which this tension is applied intraoperatively are factors under the surgeon's control. The literature suggests the best tensioning strategy for single bundle reconstructions is at medium tension in full extension, while tensioning multiple bundles is best done at 20° at lower overall tension. Graft tensioning should be individualized with attention paid to graft choice and fixation. Generally, stiffer grafts are thought to require additional force to create the same amount of lengthening. For example, bone-patellar tendon-bone grafts tend to be stiffer than quadrupled hamstring grafts and the native anterior cruciate ligament. Hamstring grafts also are thought to exhibit greater stress relaxation over time, thus elongating and potentially causing increased laxity over time. Pretensioning may eliminate some postoperative graft creep, typically more of an issue with hamstring grafts.

Single-Tunnel Double-Bundle-Like Effect With Footprint Enhancing Anterior Cruciate Ligament Reconstruction

The anterior cruciate ligament (ACL) consists of an anteromedial bundle and a posterolateral bundle giving anteroposterior and rotational stability. It's one of the most commonly injured ligaments and also one of the most commonly performed arthroscopic procedures. Management of ACL injuries is one of the most frequently studied subjects in the literature. Surgical management of ACL injuries varies from extraarticular tenodesis to arthroscopic transtibial reconstruction to double-bundle reconstruction to anatomic single-bundle reconstruction. Although double-bundle ACL reconstruction gives more rotational stability than anatomic single-bundle, functional outcome of both are the same, but the complication rates are much higher for double-bundle reconstruction. Hence, anatomic single-bundle ACL reconstruction has gained popularity. The femoral and tibial footprint of the ACL varies in shape and size; it can be oval, elliptical, rectangular, C-shape, and more. But all available ACL reconstruction techniques prepare a circular tunnel; hence, the footprint coverage of the native ACL is maximum after double-bundle reconstruction and less after anatomic single-bundle reconstruction. So, to have the benefit of double-bundle reconstruction with a single tunnel, we propose our technique of a single-tunnel double-bundle-like effect, with the footprint enhancing ACL reconstruction using our newly designed tunnel dilators.

Dual fluoroscopic imaging and CT-based finite element modelling to estimate forces and stresses of grafts in anatomical single-bundle ACL reconstruction with different femoral tunnels

PURPOSE

Little is known about the in vivo forces and stresses on grafts used in anterior cruciate ligament (ACL) reconstruction. The aims of this study were to evaluate and compare the forces and stresses on grafts used in anatomical single-bundle ACL reconstruction at different locations of the femoral footprint (anterior vs middle vs posterior; high vs middle vs low) during a lunge motion.

METHODS

Establish subject-specific finite element models with different graft's tunnel loci to represent the primary ACL reconstructions. A displacement controlled finite element method was used to simulate lunge motions (full extension to ~ 100° of flexion) with six-degree-of-freedom knee kinematics data obtained from the validated dual fluoroscopic imaging techniques. The reaction force of the femur and maximal principal stresses of the grafts were subsequently calculated during knee flexion.

RESULTS

Increased and decreased graft forces were observed when the grafts were located higher and lower on the femoral footprint, respectively; anterior and posterior graft placement did not significantly affect the graft force. Lower and posterior graft placement resulted in less stress on the graft at higher degrees of flexion; there were no significant differences in stress when the grafts were placed from 0° to 30° of flexion on the femoral footprint.

CONCLUSION

The proposed method is able to simulate knee joint motion based on in vivo kinematics. The results demonstrate that posterior to the centre of the femoral footprint is the strategic location for graft placement, and this placement results in anatomical graft behaviour with a low stress state.

New insights in anterior cruciate ligament morphology: implications for anterior cruciate ligament reconstruction surgeries

The frequency of injury of anterior cruciate ligament (ACL), the importance of anatomy in surgical repair and potential of the injured ACL to predispose to osteoarthritis necessitates the need for understanding its precise anatomy. Available studies have focussed on tunnel positioning and hence attachment site of the ligament. Few studies which have focussed on morphology reflect ambiguities in size, fibre bundle, number and disposition. Since a near anatomical repair of the ACL is the treatment of choice, the present study was planned to describe the morphology of ACL. Twenty-two ACL (11 right and 11 left) isolated from knee joints of collection of adult embalmed lower limbs were utilised for the study. The ACL morphology and morphometry were studied for footprints and fibre bundles. Three distinct bundles of differing lengths constitute a spiral ACL complex. These bundles are positioned as- intermediate with posteromedial and anterolateral flanking in respective positions. The tibial and femoral footprints are paw-shaped and oval respectively. Tibial footprints are approximately 2.5 times larger in area than the femoral footprints. The unique morphology of ACL vis a vis its spiralization, and its mechanical advantage of in terminal extension and conjunct rotation of knee (which are peculiarly human trait) are discussed. It is recommended to utilize the concept of spiralization and differing bundle length in ACL surgeries to achieve the favourable clinical outcome.

Central patellar portal placement frequently provokes anterior knee compartment radiological abnormalities in anterior cruciate ligament reconstruction

PURPOSE

A central patellar (CP) portal can be used to view the native femoral insertion site of the anterior cruciate ligament (ACL). It aids in the drilling of an anatomical tunnel; however, its impact on the patellar tendon and the infrapatellar fat pad remains a concern. The aim of this study was to investigate complications associated with the CP portal use in arthroscopic ACL reconstruction (ACLR).

METHODS

A total of 105 patients (107 knees, 60 females) who underwent ACLR with a CP portal from 2012 to 2017 were included in this study. The mean age was 28.3 ± 12.4 years. All surgeries were single-bundle reconstructions using the trans-tibial technique via the CP and anteromedial portals. Post-operative events, magnetic resonance imaging (MRI), and arthroscopic findings associated with CP portal creation were evaluated.

RESULTS

Five patients (4.7%) had symptomatic postoperative complications, which included two patients with patellar tendonitis and three patients with fibrosis in the anterior knee compartment. Abnormal signal intensity of the patellar tendon on MRI and increased thickness at the CP portal area were found in 18 of 25 knees (72%). Three of 56 knees (5.4%) that underwent second-look arthroscopy showed fibrosis of the infrapatellar fat pad. Seven patients (12.5%) showed hypertrophy of the ligamentum mucosum.

CONCLUSIONS

The rate of symptomatic complications associated with CP portal placement was 4.7%; however, abnormal MRI or follow-up arthroscopy findings were much higher than clinically symptomatic patients. This study suggests that CP portal placement could provoke anterior knee compartment fibrosis or hypertrophy.

LEVEL OF EVIDENCE

IV.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft through Single Femoral Tunnel and Single Branched Tibial Tunnel

Conventional single-bundle anterior cruciate ligament (ACL) reconstruction cannot improve the rotational stability of the knee. Traditional double-bundle ACL reconstruction requires is demanding, complex, time- and implant consuming, and associated with a high incidence of complications. Double-bundle ACL reconstruction using a free quadriceps tendon autograft through 3 independent tunnels provides some advantage, but the antegrade graft passage, tibial tunnel confluence, and graft site morbidity represent disadvantages. This Technical Note describes a modification of double-bundle ACL reconstruction using the hamstring tendon autograft through a single branched tibial tunnel and a single femoral tunnel using 2 interference screws (Arthrex, Naples, FL). The gracilis tendon autograft is passed through tibial tunnel stem to the posterolateral tibial tunnel branch to the posterolateral position in the femoral tunnel. The semitendinosus tendon autograft is passed through the tibial tunnel stem to the anteromedial tibial tunnel branch to the anteromedial position in the femoral tunnel. Both grafts are fixed by 2 interference screws: 1 at the femoral tunnel and 1 at the tibial tunnel stem with the knee at 20° flexion.

Effect of Dynamic Changes in Anterior Cruciate Ligament In Situ Graft Force on the Biological Healing Response of the Graft-Tunnel Interface

BACKGROUND

Anterior cruciate ligament (ACL) grafts that are placed for reconstruction are subject to complex forces. Current "anatomic" ACL reconstruction techniques may result in greater in situ graft forces. The biological effect of changing magnitudes of ACL graft force on graft-tunnel osseointegration is not well understood.

PURPOSE

The research objective is to determine how mechanical force on the ACL graft during knee motion affects tendon healing in the tunnel.

STUDY DESIGN

Controlled laboratory study.

METHODS

Male rats (N = 120) underwent unilateral ACL reconstruction with a soft tissue flexor tendon autograft. ACL graft force was modulated by different femoral tunnel positions at the time of surgery to create different graft force patterns with knee motion. External fixators were used to eliminate graft load during cage activity. A custom knee flexion device was used to deliver graft load through controlled daily knee motion. Graft-tunnel healing was then assessed via biomechanical, micro-computed tomography, and histological analyses.

RESULTS

ACL graft-tunnel healing was sensitive to dynamic changes in graft forces with postoperative knee motion. High ACL graft force with joint motion resulted in early inferior ACL graft load to failure as compared with knees that had low-force ACL grafts and joint motion and knees that were immobilized (mean ± SD: 5.50 ± 2.30 N vs 9.91 ± 3.54 N [ P = .013] and 10.90 ± 2.8 N [ P = .001], respectively). Greater femoral bone volume fraction was seen in immobilized knees and knees with low-force ACL grafts when compared with high-force ACL grafts at 3 and 6 weeks.

CONCLUSION

The authors were able to demonstrate that ACL graft-tunnel incorporation is sensitive to dynamic changes in ACL graft force with joint motion. Early high forces on the ACL graft appear to impair graft-tunnel osseointegration.

CLINICAL RELEVANCE

Current "anatomic" techniques of ACL reconstruction may result in greater graft excursion and force with knee motion. Our results suggest that the postoperative rehabilitation regimen may need to be modified during the early phase of healing to protect the reconstruction.

Effects of initial graft tension on femoral tunnel widening after anatomic anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft

INTRODUCTION

The effects of initial graft tension upon tunnel widening (TW) following anatomic anterior cruciate ligament (ACL) reconstruction have not been elucidated. The purpose of this study was to retrospectively investigate the effect of two different graft-tensioning protocols upon femoral TW following anatomic ACL reconstruction using a bone-patellar tendon-bone (BPTB) graft and a three-dimensional (3D) computed tomography (CT) model.

METHODS

Forty-three patients who underwent isolated ACL reconstruction using BPTB grafts were included in this study. In 18 out of the 43 patients, the graft was fixed at full knee extension with manual maximum pull (Group H). These patients were compared with 25 patients in whom the BPTB graft was fixed at full knee extension with 80-N pull (Group L). Tunnel aperture area was measured using 3D CT 1 week and 1 year postoperatively, thus enabling us to calculate the percentage change in the area of femoral tunnel aperture. Clinical assessment was performed 1 year postoperatively, corresponding to the time period of CT assessment, and involved the evaluation of Lysholm score, anterior knee stability using a KneeLax3 arthrometer, and the pivot-shift test.

RESULTS

When measured at 1 year postoperatively, the mean area of the femoral tunnel aperture had increased by 78.6 ± 36.8% in Group H when compared with at 1 week postoperatively, whereas that of Group L had increased by 27.7 ± 32.3%. Furthermore, TW (%) in Group H was significantly greater than that of Group L (P < 0.001). No significant differences were detected between the two groups with regard to any of the clinical outcomes evaluated.

CONCLUSION

High levels of initial graft tension resulted in greater TW of the femoral tunnel aperture following anatomical ACL reconstruction using BPTB grafts. However, such levels of graft tension did not affect clinical outcome.

Influence of tibial hybrid fixation on graft tension and stability in ACL double-bundle reconstruction

PURPOSE

Initial graft tension in anterior cruciate ligament (ACL) reconstruction affects stability and tension loss at follow-up. This study investigated the influence of hybrid tibial fixation in 3-tunnel double-bundle ACL reconstruction on initial graft tension and tension change and stability under anterior and combined rotatory loads.

METHODS

Eleven fresh-frozen cadaveric knees were reconstructed with an ACL double bundle using a 3-tunnel technique. Grafts were tightened to 80 N in 60° (AM bundle) and 15° (PL bundle) of flexion. Anterior tibial translation under 134 N of anterior shear load and translation under combined rotatory and valgus loads (10 Nm valgus stress, 4 Nm internal tibial torque) were determined at 0°, 30°, 60°, and 90° flexion. In addition, graft tension under continuous passive motion was determined. Intact, ACL-resected and ACL-reconstructed joints with either tibial extracortical graft fixation or extracortical plus supplemental aperture graft fixation (hybrid fixation) were tested.

RESULTS

Hybrid fixation did not increase graft tension in either bundle during fixation or in motion without additional load. AM-bundle tension increased (p < 0.05) at 0° under combined rotatory and valgus loads and at 30° and 60° under both loading conditions without decreasing the anterior tibial translation. PL-bundle tension increased (p < 0.05) only at 90° under combined rotatory and valgus loads.

CONCLUSIONS

Tibial hybrid fixation in 3-tunnel double-bundle ACL reconstruction increases time-zero AM- and PL-bundle tensions under loading conditions, generating greater construct stiffness. This could lead to a longer preservation of ACL-graft stability in clinical follow-up before bony incorporation.

ACL double-bundle reconstruction with one tibial tunnel provides equal stability compared to two tibial tunnels

PURPOSE

The purpose of this study was to investigate whether an anterior cruciate ligament (ACL) double-bundle reconstruction with one tibial tunnel displays the same in vitro stability as a conventional double-bundle reconstruction with two tibial tunnels when using the same tensioning protocol.

METHODS

In 11 fresh-frozen cadaveric knees, ACL double-bundle reconstruction with one and two tibial tunnels was performed. The two grafts were tightened using 80 N in different flexion angles (anteromedial-bundle at 60° and posterolateral-bundle at 15°). Anterior tibial translation (134 N) and translation with combined rotatory and valgus loads (10 Nm valgus stress and 4 Nm internal tibial torque) were determined at 0°, 30°, 60° and 90° flexion. Measurements were taken in intact ACL, resected ACL, three-tunnel reconstruction and four-tunnel reconstruction. Additionally, the tension on the grafts was determined. Student's t test was performed for statistical analysis of the related samples. Significance was set at p < 0.017 according to Bonferroni correction.

RESULTS

The two reconstructive techniques displayed no significant differences in comparison with the intact ACL in anterior tibial translation at 0°, 60° and 90° of flexion. The same results were obtained for the anterior tibial translation with a combined rotatory load at 60° and 90°. When directly comparing both reconstructive techniques, there were no significant differences for the anterior tibial translation and combined rotatory load at all flexion angles. The measured tension on grafts displayed similar load sharing between both bundles. Except at full extension, both grafts displayed a significantly different tension increase under anterior tibial translation for both techniques (p = 0.0086).

CONCLUSIONS

Tightening both bundles in ACL double-bundle reconstruction with one or two tibial tunnels in different flexion angles achieved comparable restoration of stability, although there was different load sharing on the bundles. With regard to individualized ACL reconstruction, the double-bundle technique with one tibial tunnel offers a possibility to address small tibial insertion sites without compromising the advantages of a double-bundle procedure.

Use of Robotic Manipulators to Study Diarthrodial Joint Function

Diarthrodial joint function is mediated by a complex interaction between bones, ligaments, capsules, articular cartilage, and muscles. To gain a better understanding of injury mechanisms and to improve surgical procedures, an improved understanding of the structure and function of diarthrodial joints needs to be obtained. Thus, robotic testing systems have been developed to measure the resulting kinematics of diarthrodial joints as well as the in situ forces in ligaments and their replacement grafts in response to external loading conditions. These six degrees-of-freedom (DOF) testing systems can be controlled in either position or force modes to simulate physiological loading conditions or clinical exams. Recent advances allow kinematic, in situ force, and strain data to be measured continuously throughout the range of joint motion using velocity-impedance control, and in vivo kinematic data to be reproduced on cadaveric specimens to determine in situ forces during physiologic motions. The principle of superposition can also be used to determine the in situ forces carried by capsular tissue in the longitudinal direction after separation from the rest of the capsule as well as the interaction forces with the surrounding tissue. Finally, robotic testing systems can be used to simulate soft tissue injury mechanisms, and computational models can be validated using the kinematic and force data to help predict in vivo stresses and strains present in these tissues. The goal of these analyses is to help improve surgical repair procedures and postoperative rehabilitation protocols. In the future, more information is needed regarding the complex in vivo loads applied to diarthrodial joints during clinical exams and activities of daily living to serve as input to the robotic testing systems. Improving the capability to accurately reproduce in vivo kinematics with robotic testing systems should also be examined.

Effect of fixation angle and graft tension in double-bundle anterior cruciate ligament reconstruction on knee biomechanics

PURPOSE

To compare the effect of graft fixation angle and tension in double-bundle anterior cruciate ligament (ACL) reconstruction on knee biomechanics.

METHODS

Fourteen cadaver knees were tested using a robotic system under two loadings: (1) an 89-N anterior tibial load (ATL) at full extension (FE), 15°, 30°, 45°, 60°, and 90°, and (2) combined 7 N m valgus and 5 N m internal tibial torques (simulated pivot-shift test) at FE, 15° and 30°. Four graft fixation angles and tensions were used for the anteromedial (AM) and posterolateral (PL) bundles, respectively: (Recon 1) 30°/20N and FE/20N, (Recon 2) 30°/30N and FE/10N, (Recon 3) 45°/20N and 15°/20N, and (Recon 4) 45°/30N and 15°/10N.

RESULTS

All fixation protocols closely restored the intact knee kinematics under ATL and simulated pivot-shift loading. For the AM bundle under ATL, the in situ force (ISF) with Recon 3 at the FE was significantly lower than that of the intact knee. For the PL bundle under ATL, the ISF with Recon 3 at the FE, 15° and 30° was significantly higher than that of the intact knee. In PL bundle under simulated pivot-shift loading, the ISF with Recon 1 and Recon 2 at FE was lower and the ISF of the PL bundle with Recon 3 at the 15° was higher than that of the intact knee.

CONCLUSION

The AM-45°/30N and PL-15°/10N fixation most closely matched intact knee kinematics; however, stabilizing the knee during anterior tibial translation may risk an imbalance of the AM and the PL bundle loading. The results indicate that ACL bundle forces may not be restored even if the clinical assessment shows good results with the Lachman test and pivot-shift test. This may alter the loading on other structures of the knee.

A new technique in double-bundle anterior cruciate ligament reconstruction with implant-free tibial fixation

PURPOSE

This case-series outcome study presents a surgical technique for anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with 4-tunnel using two interference screws. There was a 2-year minimum follow-up.

METHODS

From January to December 2009, an ACL 4-tunnel, anatomic, double-bundle reconstruction was performed on 27 patients. Double-strand hamstring tendon grafts were used in each femoral tunnel as well as two interference screws. Tibial fixation was insured through manual tension, by tying non-absorbable sutures on the bone bridge between the two tunnels at 20° of knee flexion. Clinical assessments included the International Knee Documentation Committee (IKDC) and Lysholm knee scores, range of motion (ROM), pivot-shift test, single-leg hop, and quadriceps-hamstrings strength tests using a hand-held dynamometer. Anterior knee laxity was also assessed using a rolimeter. A single examiner performed all testing pre-operatively at 6 months and during the 2-year follow-up.

RESULTS

All patients were assessed during the 2-year follow-up. At that time, 92 % of the patients presented normal anterior laxity (average, 1.3 ± 0.5 mm) and rotational knee stability. No statistical side-to-side difference was found for ROM, muscle strength, single-leg hop, and function (n.s.). All patients presented a normal knee function according to the IKDC and the Lysholm score. In addition, no infection, graft failure, or pain were observed at the harvesting site.

CONCLUSION

The study shows that satisfactory results in relation to knee laxity, function, and strength can be achieved with the implant-free tibial fixation in the ACL double-bundle reconstruction with two interference screws.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Effect of Initial Graft Tension on Knee Stability and Graft Tension Pattern in Double-Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE

To determine the initial minimal tension for restoring knee stability during double-bundle anterior cruciate ligament (ACL) reconstruction in vivo.

METHODS

Patients who underwent primary double-bundle ACL reconstruction with an autologous semitendinosus tendon during 2012 were included. The bundles were fixed to a graft-tensioning system during surgery. Initial graft tensions were set to the following tensions per 6 mm in graft diameter: (1) 30 N, (2) 25 N, and (3) 20 N. Bundle tension was recorded during knee flexion-extension and in response to anterior or rotatory loads. In addition, anterior knee laxity was measured with the KT-1000 arthrometer (MEDmetric, San Diego, CA), and the pivot-shift test was evaluated.

RESULTS

Sixty patients were evaluated. The tension curves of both bundles among different initial tension settings were significantly different (P < .0001), with the tension in the 30-N setting being highest and that in the 20-N setting being lowest. The tension in both bundles showed reciprocal pattern during flexion-extension (P = .019). The tension of the posterolateral bundle graft was significantly lower than that of the anteromedial bundle graft in response to the anterior load at all settings (P = .0017, P = .0019, and P = .0021 at 30° in the 30-N, 25-N, and 20-N settings, respectively, and P < .0001 at 90° at all settings), whereas the tensions in both bundles in response to rotatory loads were equivalent. Two cases showed a grade 1 pivot shift in the 20-N setting, whereas no case showed a positive pivot shift in the other settings. KT measurements in the 30-N and 25-N settings showed no difference.

CONCLUSIONS

In double-bundle ACL reconstruction, initial tension could be set as low as 25 N; however, initial tension of 20 N is not recommended because it might result in residual pivot shift in some cases, although the pivot-shift difference was not significant.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Effect of posterolateral bundle graft fixation angles on clinical outcomes in double-bundle anterior cruciate ligament reconstruction: a randomized controlled trial

BACKGROUND

In double-bundle (DB) anterior cruciate ligament (ACL) reconstruction, no consensus exists on an optimal setting for the posterolateral bundle (PLB) graft fixation angles.

HYPOTHESIS

Different PLB fixation angles would affect clinical outcomes in DB ACL reconstruction.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

This study prospectively included 90 patients who underwent primary DB ACL reconstruction with an autologous semitendinosus tendon. The PLB fixation angles were randomly set as follows: 0° of flexion (P0; n=30), 20° (P20; n=30), and 45° (P45; n=30). In all groups, the anteromedial bundle was fixed at 20° of flexion. The following evaluation methods were used at the preoperative period and at 3, 6, and 9 months and 1 and 2 years after the surgery: clinical examination, KT-1000 arthrometer measurement, muscle strength, Tegner score, Lysholm score, and subjective rating scale regarding patient satisfaction and sports performance levels. Graft retear, contralateral ACL tear, and additional meniscus surgery were also recorded.

RESULTS

Seventy-five patients (P0, n=25; P20, n=26; P45, n=24) who were followed for 2 years were evaluated. Preoperatively, there were no differences among the groups. Postoperatively, pivot-shift test results in the P0 and P20 groups were better than those in the P45 group (P0, n=23 graded negative and 2 graded 1+; P20, n=23 and 2; P45, n=15 and 7, respectively; P0 vs P45: P=.038 and P20 vs P45: P=.038). Average KT-1000 arthrometer laxity measurements were better in the P20 group than in the P45 group (P0, 0.4 mm; P20, 0.3 mm; P45, 1.3 mm; P20 vs P45: P=.048), and there were more patients with graft failure (KT-1000 measurement, ≥4 mm) in the P45 group (n=3) than the P0 and P20 groups (each, n=0). There were no significant differences in range of motion, other laxity tests, muscle strength, Tegner score, Lysholm score, subjective rating scale, or additional surgery.

CONCLUSION

In DB ACL reconstruction, when the anteromedial bundle was fixed at 20° of flexion, fixation of the PLB at 45° was worse than fixation at 0° and 20° with respect to anterior and rotational stability during the 2-year follow-up. KT-1000 arthrometer measurements and pivot-shift test results were significantly worse, and there were more patients with graft failure in the P45 group. There were no differences among groups in other findings.

Effect of lateral meniscal root tear on the stability of the anterior cruciate ligament-deficient knee

BACKGROUND

Meniscal root tears are an increasingly recognized subset of meniscal injury. The menisci are critical secondary stabilizers of the anterior cruciate ligament (ACL). The kinematic effect of lateral meniscus posterior root tear in the setting of ACL injury is not known.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine the effect of tear of the lateral meniscal root on stability of the ACL-deficient knee. The hypothesis was that disruption of the lateral meniscal root will further destabilize the ACL-deficient knee during a simulated pivot shift.

STUDY DESIGN

Controlled laboratory study.

METHODS

Pivot-shift testing of 8 fresh-frozen cadaveric knees was performed after attachment of photoreflective flags and preparation of CT scans. Each knee was mounted in a custom activity simulator and dynamically loaded from 15° to 90° of flexion with all the permutations of the following: iliotibial band force (50, 75, 100, 125, 150, and 175 N), internal rotation moments (1, 2, and 3 N·m), and valgus moments (5 and 7 N·m). In addition, anterior stability tests were performed by applying a 90-N anterior force to the tibia at flexion angles of 15°, 30°, 45°, 60°, and 90°. During each test, the anterior tibial translation and rotation of the tibia were measured with a high-resolution multiple infrared camera motion analysis system for the following 3 conditions: ACL-intact (ACL-I), ACL-deficient (ACL-D), and ACL-deficient/lateral meniscal posterior root avulsion (ACL-D/LMR-A).

RESULTS

A pivot-shift phenomenon was observed in the ACL-D and ACL-D/LMR-A conditions. The mean tibial translation of the lateral tibial condyle during the pivot-shift maneuver was 2.62 ± 0.53 mm for the ACL-I knees, 6.01 ± 0.51 mm for the ACL-D knees (P value vs. intact: .0005), and 8.13 ± 0.75 mm for the ACL-D/LMR-A knees (P value vs intact: <.0001). During the pivot-shift maneuver, translation was significantly increased in the ACL-D/LMR-A condition compared with the ACL-D condition (P = .0146). Compared with the intact group, anterior tibial translation during the Lachman maneuver also increased at 30° and 90° of flexion in the ACL-D group (P < .0001) and the ACL-D/LM group (P < .0001). No statistically significant difference was found between the ACL-D and ACL-D/LMR-A groups during the Lachman maneuver at 30° and 90° (P = .16 and .72, respectively).

CONCLUSION

A tear of the lateral meniscal posterior root further reduces the stability of the ACL-deficient knee during rotational loading.

CLINICAL RELEVANCE

This study shows that lateral meniscal root injury further destabilizes the ACL-deficient knee and thus advances the concept that the lateral meniscus is a secondary stabilizer of the knee under pivot-shift loading. In the absence of stronger evidence, the study data suggest a rationale for surgical repair of lateral meniscal root tears encountered in the setting of ACL tears.

Individualized anatomic anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) injuries are often seen in young participants in sports such as soccer, football, and basketball. Treatment options include conservative management as well as surgical intervention, with the goal of enabling the patient to return to cutting and pivoting sports and activities. Individualized anatomic ACL reconstruction is a surgical technique that tailors the procedure to the individual patient using preoperative measurements on plain radiographs and magnetic resonance imaging and intraoperative measurement to map the patients' native ACL anatomy in order to replicate it as closely as possible. Anatomic ACL reconstruction, therefore, is defined as reconstruction of the ACL to its native dimensions, collagen orientation, and insertion site. The surgical reconstruction is followed by a specific rehabilitation protocol that is designed to enable the patient to regain muscle strength and proprioception while facilitating healing of the reconstructed ACL prior to the patient's returning to sports activities.

Effect of femoral tunnel position on graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

To evaluate the effect of the femoral tunnel position of the anteromedial bundle (AMB) and the posterolateral bundle (PLB) on the graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Forty-five patients who underwent anatomic double-bundle ACL reconstruction were included. AMB and PLB were provisionally fixed to a graft tensioning system in the following settings during surgery: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion-extension. A pivot shift test was also evaluated. Femoral tunnel positions of the AMB and PLB were then assessed by three-dimensional computed tomography, and the correlation between femoral tunnel position and tension change pattern or residual pivot shift was evaluated.

RESULTS

The depth of the PLB tunnel position was correlated with the extent of tension reduction in the PLB between 0° and 30° irrespective of graft fixation settings, while neither the AMB tunnel position nor the height of the PLB tunnel position affected the tension change pattern. Ten cases showed grade 1 pivot shift only in the A20P0 setting. The PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases (27.5 ± 6.2 and 34.1 ± 5.5%, respectively, P = 0.002).

CONCLUSIONS

In anatomic double-bundle reconstruction, deeper PLB tunnel position was correlated with the larger tension reduction in the PLB between 0° and 30°. Fixation of the AMB at 20° and the PLB at 0° resulted in residual pivot shift phenomenon in 10/45 cases, and the PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases. In anatomic double-bundle reconstruction, the placement of PLB femoral tunnel must not be too deep, as it might lead to significant tension reduction in the PLB near extension and thus insufficient tension in the PLB, resulting in residual pivot shift phenomenon.

LEVEL OF EVIDENCE

IV.

The concept of individualized anatomic anterior cruciate ligament (ACL) reconstruction

PURPOSE

To describe the concept of individualized anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

The PubMed/Medline database was searched using keywords pertaining to ACL reconstruction. Relevant articles were reviewed in order to summarize important concepts of individualized surgery in ACL reconstruction. Surgical experiences with case examples are also highlighted.

RESULTS

Individualized ACL surgery allows for the customization of surgery to each individual patient. Accounting for graft selection and other characteristics such as anatomy, lifestyle and activity preferences may provide the patient with the best potential for a successful outcome. The surgeon should be comfortable with a variety of graft harvests and surgical techniques when practicing individualized surgery.

CONCLUSION

Individualized anatomic ACL reconstruction is founded on the objective evaluation of functional anatomy and individual characteristics, thereby restoring the ACL as closely as possible to the native anatomy and function. The adoption and subsequent use of individualized surgery may facilitate improved clinical as well as objective outcomes, particularly in the long term.

LEVEL OF EVIDENCE

V.

A Preliminary In Vivo Assessment of Anterior Cruciate Ligament-Deficient Knee Kinematics With the KneeM Device: A New Method to Assess Rotatory Laxity Using Open MRI

BACKGROUND

Methods of objectively measuring rotational knee laxity are either experimental or difficult to use in daily practice. A new method has been developed to quantitatively assess rotatory laxity using an open MRI system and new tool, the KneeM device.

PURPOSE/HYPOTHESIS

To perform a preliminary evaluation of a novel knee rotation measurement device to assess knee kinematics during flexion in an MRI field, in both anterior cruciate ligament (ACL)-deficient and healthy contralateral knees. The hypothesis was that the KneeM device would allow in vivo reproduction and analysis of knee kinematics during flexion in healthy and ACL-deficient knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten subjects (7 men and 3 women; mean age ± standard deviation, 32.3 ± 9.4 years) with ACL-deficient knees and contralateral uninjured knees participated in the study. An open MRI was performed with the KneeM device at a mean 4.9 months (range, 3.0-7 months) after ACL injury. The device exerted on the knee an anterior drawer force of 100 N, with an internal rotation of 20°, through the range of flexion (0°, 20°, 40°, and 60°). Both ACL-deficient and healthy contralateral knees were analyzed using the Iwaki method.

RESULTS

There was no statistical difference of anterior translation in the medial compartment between intact and ACL-deficient knees at all degrees of flexion. However, significant differences in the anterior translation of the lateral compartment were observed between ACL-deficient and intact contralateral knees at 0° and 20° of flexion (P = .005 and P = .002, respectively). Between 20° and 40°, the lateral plateau of ACL-deficient knees translated 7.7 mm posteriorly, whereas the medial compartment remained stable, reflecting a sudden external rotation of the lateral plateau under the femoral condyle.

CONCLUSION

This preliminary study suggests that measurement of tibiofemoral movements in both compartments during flexion using the KneeM device was useful for quantifying rotatory laxity in ACL-deficient knees. Moreover, this device seemed to allow a "mechanized pivot shift" and allowed reproduction of the "pivot" phase in the MRI field between 20° and 40° of flexion.

CLINICAL RELEVANCE

This device could be used for diagnostic purposes or to investigate the outcomes of ACL reconstructions.

Anatomic double-bundle anterior cruciate ligament reconstruction using in situ hamstring graft with 4 tunnels

A careful review of the literature suggests that a significant number of patients undergoing anterior cruciate ligament (ACL) reconstruction have less-than-optimal results. Although overall outcomes of ACL reconstruction are favorable, there remains considerable room for improvement. Anatomically, the ACL consists of 2 major functional bundles, the anteromedial bundle and the posterolateral bundle. Biomechanically, both bundles contribute significantly to the anterior and rotational stability of the knee. Therefore anatomic double-bundle ACL reconstruction techniques may further improve the outcomes in ACL surgery. This article presents a technique for arthroscopic double-bundle ACL reconstruction that includes the use of 2 femoral and 2 tibial tunnels to restore both the anteromedial and posterolateral bundles of the ACL with minimal hardware for fixation.

Effect of posterolateral bundle graft fixation angles on graft tension curves and load sharing in double-bundle anterior cruciate ligament reconstruction using a transtibial drilling technique

PURPOSE

To evaluate the effect of posterolateral bundle (PLB) graft fixation angles on graft tension curves and load sharing between the anteromedial bundle (AMB) and the PLB in double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-four patients who underwent double-bundle ACL reconstruction were included in this study. AMB and PLB were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion-extension and in response to anterior or rotatory loads. A pivot-shift test, as well as factors affecting the residual pivot-shift, was also evaluated.

RESULTS

A20P45 created reciprocal tension curves and load sharing, in which the tension in both bundles was equivalent during flexion-extension and during each loading test at 30°. In A20P0, the tension of the AMB was constantly higher than that of the PLB. Seven patients showed grade 1 pivot-shift phenomenon in A20P0, whereas no patient showed a positive pivot-shift at other settings. Larger tension reduction of the PLB between 0° and 30° and smaller load sharing of the PLB were significant factors affecting residual pivot-shift.

CONCLUSIONS

In double-bundle ACL reconstruction, fixation of the AMB at 20° and the PLB at 45° created reciprocal tension curves and load sharing between the bundles. Fixation of the AMB at 20° and the PLB at 0° led to insufficient tension in the PLB, resulting in a residual pivot-shift phenomenon in 7 of 24 patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Clinical and second-look arthroscopic study comparing 2 tibial landmarks for tunnel insertions during double-bundle ACL reconstruction with a minimum 2-year follow-up

BACKGROUND

Few studies have reported the clinical results of tibial tunnel placement during double-bundle anterior cruciate ligament (ACL) reconstruction. It is important to recognize arthroscopic tibial landmarks during this procedure.

HYPOTHESIS

During arthroscopic double-bundle ACL reconstruction, anterior tibial landmarks such as the intermeniscal (transverse) ligament and the Parsons knob for the anteromedial (AM) tunnel provide better knee stability and clinical outcomes than do posterior tibial landmarks such as the fovea anterior to the tibial intertubercle ridge for the posterolateral (PL) tunnel.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 121 patients underwent primary unilateral double-bundle ACL reconstructions using autogenous medial hamstring tendons. Fifty-nine patients from December 2008 through July 2009 underwent reconstructions using posterior tibial landmarks (PL group), and 62 patients from August 2009 through February 2010 underwent reconstructions using anterior tibial landmarks (AM group). Forty-seven patients (follow-up rate, 79.7%) in the PL group and 52 patients (follow-up rate, 83.9%) in the AM group underwent second-look arthroscopy and clinical evaluations under anesthesia at 1 year postoperatively and 3-dimensional computed tomography (3-D CT) evaluations at 3 weeks postoperatively.

RESULTS

Lachman test results indicated no significant differences, and pivot-shift test results were significantly lower in the AM group (P = .007). Mean side-to-side differences using the Telos device at 130 N were significantly lower in the AM group (1.4 ± 1.6 mm) compared with the PL group (2.4 ± 2.5 mm) (P = .012). Results for lack of extension were not significantly different, while those for lack of flexion were significantly better in the AM group than in the PL group (P = .036). No significant differences were observed in the Lysholm scores between the groups. In measurements of the tibial tunnel position by 3-D CT, with regard to anteroposterior depth, the AM bundle of the PL group was 41.6% ± 7.4% and the AM group was 29.1% ± 5.3% (P < .001), and the PL bundle of the PL group was 55.6% ± 7.7% and the AM group was 46.4% ± 5.8% (P < .001). No significant differences were found in mediolateral width. In second-look arthroscopy, there were significant differences with respect to the synovial cover with regard to the AM bundle (P = .024).

CONCLUSION

Patients in the AM group showed better knee stability and range of motion than those in the PL group. Transverse ligaments and Parsons knobs proved to be useful landmarks during ACL reconstruction.

Anatomic single-bundle anterior cruciate ligament reconstruction in Asian population

BACKGROUND

Non-anatomic tunnel placement, which leads to failure in double-bundle anterior cruciate ligament (ACL), has focused greater attention on single-bundle ACL reconstruction. However, single-bundle ACL with 2- to 4-strand autogenous hamstring tendon graft always showed weak graft strength.

METHODS

To solve this problem, single-bundle ACL with 6-strand autogenous hamstring tendon graft was performed on 32 Asian patients in this study. At 24 months post-operatively, all patients were evaluated with Lysholm knee scores, Tegner activity level and KT-1000 examinations.

RESULTS

The results demonstrated that no patients showed knee extension limitation. Of the 32 patients, there were 26 negative and 6 positive 1° in Lachman test; 31 negative and 1 positive 1° in pivot-shift test. There were four patients with a 5° flexion limitation. The median Lysholm score increased from 45 preoperatively to 92 post-operatively (P < 0.001). The median Tegner sport level score increased from 1 preoperatively to 4 post-operatively (P < 0.001). KT-1000 examination revealed that the median anterior laxity at 25° of flexion was 6.3 mm preoperatively and 1.7 mm post-operatively (P < 0.001).

CONCLUSIONS

The data showed that arthroscopic central anatomic single-bundle ACL reconstruction with 6-strand autogenous hamstring tendon graft is a reliable method to restore stabilization and function of the knee.

Comparison of 2 femoral tunnel locations in anatomic single-bundle anterior cruciate ligament reconstruction: a biomechanical study

PURPOSE

To evaluate knee stability after anterior cruciate ligament (ACL) reconstruction using 2 modern clinically relevant single-bundle constructs.

METHODS

Two arthroscopic ACL reconstructions were performed on 6 fresh-frozen human cadaveric knees using bone-patellar tendon-bone autografts. The tibial tunnel was centered in the anatomic tibial footprint. The femoral tunnel was reamed through the anteromedial (AM) portal and centered alternately in either the AM portion of the femoral footprint (center-AM) or the center of the femoral footprint (center-center). Two external loading conditions were applied: (1) a 134-N anterior tibial load and (2) a 10-Nm valgus load combined with a 5-Nm internal tibial torque. Resulting kinematics were determined under 4 conditions: (1) ACL intact, (2) ACL deficient, (3) center-AM reconstruction, and (4) center-center reconstruction.

RESULTS

In response to anterior tibial loading, anterior translation was similar in the ACL-intact knee and the 2 reconstructions at 0° to 60° of flexion but was greater in the reconstructed specimens at 90°. In response to the complex rotatory load, internal tibial rotation (ITR) at 30° of flexion was slightly greater in center-AM knees compared with ACL-intact knees (11.0° ± 0.6° v 10.5° ± 0.6°, P = .03). At other angles tested, ITR in both reconstructions was similar to the ACL-intact knee (P > .05). When we compared the 2 reconstruction alternatives, however, center-center knees exhibited greater resistance to ITR at all angles (P < .05).

CONCLUSION

Anatomic single-bundle ACL reconstruction performed with the femoral tunnel placed through the AM portal restores translational and rotational knee stability to an extent that closely approximates the ACL-intact condition. When compared with the AM femoral tunnel position, a femoral tunnel positioned in the anatomic center of the femoral origin of the ACL may further improve rotatory stability without sacrificing anterior stability.

CLINICAL RELEVANCE

This study provides additional biomechanical evidence in support of anatomic single-bundle ACL reconstruction with tunnels positioned in the center of the femoral and tibial footprints.

Measurement of the end-to-end distances between the femoral and tibial insertion sites of the anterior cruciate ligament during knee flexion and with rotational torque

PURPOSE

The aim of this study was to determine the end-to-end distance changes in anterior cruciate ligament (ACL) fibers during flexion/extension and internal/external rotation of the knee.

METHODS

The positional relation between the femur and tibia of 10 knees was digitized on a robotic system during flexion/extension and with an internal/external rotational torque (5 Nm). The ACL insertion site data, acquired by 3-dimensional scanning, were superimposed on the positional data. The end-to-end distances of 5 representative points on the femoral and tibial insertion sites of the ACL were calculated.

RESULTS

The end-to-end distances of all representative points except the most anterior points were longest at full extension and shortest at 90°. The distances of the anteromedial (AM) and posterolateral (PL) bundles were 37.2 ± 2.1 mm and 27.5 ± 2.8 mm, respectively, at full extension and 34.7 ± 2.4 mm and 20.7 ± 2.3 mm, respectively, at 90°. Only 4 knees had an isometric point, which was 1 of the 3 anterior points. Under an internal torque, both bundles became longer with statistical meaning at all flexion angles (P = .005). The end-to-end distances of all points became longest with internal torque at full extension and shortest with an external torque at 90°.

CONCLUSIONS

Only 4 of 10 specimens had an isometric point at a variable anterior point. The end-to-end distances of the AM and PL bundles were longer in extension and shorter in flexion.

CLINICAL RELEVANCE

The nonisometric tendency of the ACL and the end-to-end distance change during knee flexion/extension and internal/external rotation should be considered during ACL reconstruction to avoid overconstraint of the graft.

Factors affecting anterior knee pain following anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the prevalence of anterior knee pain in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction and to identify critical factors affecting postoperative anterior knee pain development.

METHODS

Subjects comprised 171 patients (171 knees) who underwent anatomic double-bundle ACL reconstruction with a follow-up period of ≥2 years. The procedure used bone-patellar tendon-bone plus gracilis tendon (BTB-G) in 56 knees, semitendinosus tendon (ST) in 71 knees, and ST-G in 44 knees. Clinical results and prevalence and severity of anterior knee pain were assessed at 3 months and 2 years postoperatively. Clinical variables influencing anterior knee pain development at each postoperative period were subjected to univariate analysis, followed by logistic regression analysis to identify risk factors for anterior knee pain.

RESULTS

Overall prevalences of anterior knee pain at 3 months and 2 years postoperatively were 42.0 and 11.1%, respectively. Use of BTB-G graft represented the highest prevalence of anterior knee pain between the 3 different grafts (P = 0.001); however, this statistical significance disappeared at 2 years postoperatively. Prevalence of postoperative extension deficit was significantly higher in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 3 months postoperatively. Level of quadriceps strength was significantly lower, and Lysholm score was significantly worse in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 2 years postoperatively. According to logistic regression analysis, knee extension deficit was a predisposing factor for the development of anterior knee pain at 3 months postoperatively (odds ratio, 2.76; P = 0.004); however, there was no significant predisposing factor for anterior knee pain at 2 years postoperatively.

CONCLUSIONS

Knee extension deficit was an important predisposing factor for postoperative anterior knee pain in the early postoperative period, and anterior knee pain was associated with impaired quadriceps function and inferior subjective results over 2 years postoperatively. Early recovery of full extension may prevent postoperative development of anterior knee pain and achieve successful outcomes for ACL reconstruction.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Effects of single-bundle and double-bundle ACL reconstruction on tibiofemoral compressive stresses and joint kinematics during simulated squatting

The purpose of this study was to compare tibiofemoral (TF) kinematics and TF compressive stresses between single bundle- (SB-) and double bundle-ACL reconstruction (DB-ACLR) during simulated squatting. Twelve matched pairs of fresh frozen cadaver knees were utilized. A simulated squat through 100° of knee flexion was performed in the ACL-intact joint. The ACL was transected and SB- and DB-ACLR procedures were performed in one knee of each pair. The squat was repeated. Knee kinematics were measured using a motion tracking system and the TF compressive forces were measured using thin film pressure sensors. The posterior shifts of the tibia for SB- and DB-ACLR knees were significantly greater than the ACL-intact condition for knee flexion angles 0° to 40° (p<.05). However, there was no difference between the SB- and DB-ACLR knees at any flexion angle (0° to 100°; p=.37). SB- and DB-ACLR knees had greater IE rotation than intact knees from 90° through 50° of flexion (p<.05), but not between 40° and full extension. There was no difference between SB- and DB-ACLR knees (p=.68). The TF compressive stresses of the DB-ACLR were significantly lower than intact for all angles except 10° (p=.06), whereas SB-ACLR knees did not differ from intact at flexion angles between 30° and 50° (p>.32). There were no significant differences between the two reconstruction conditions (p=.74). This study showed that there was no difference in the TF kinematics or compressive stresses between SB- and DB-ACLR, and only minor differences when compared to the intact state.

Arthroscopic evaluation of preserved ligament remnant after selective anteromedial or posterolateral bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the clinical results and morphology of the preserved bundle remnants by second-look arthroscopy postoperatively 1 year after selective anteromedial (AM) or posterolateral (PL) bundle ACL reconstruction.

METHODS

Between July 2004 and September 2009, 1,000 patients underwent arthroscopic anterior cruciate ligament (ACL) reconstruction at our hospital. Among them, 20 (2%) underwent selective AM bundle (group A) or PL bundle (group P) ACL reconstruction surgery with hamstring tendon autografts. At 1 year after surgery, 19 patients (7 male and 12 female patients; age range, 15 to 57 years) underwent second-look arthroscopic evaluations. The follow-up mean was 40.2 months (range, 24 to 70 months). We evaluated the results of manual knee laxity, anterior knee laxity measured by a Telos device (Telos, Marburg, Germany) at 130 N, Lysholm scores, and International Knee Documentation Committee evaluation form and performed evaluations of morphology by second-look arthroscopy.

RESULTS

The side-to-side difference in anterior translation by use of the Telos device at 130 N was improved to 2 ± 2 mm (postoperatively) from 6 ± 2.3 mm (preoperatively) in group A and to 1.02 ± 1.26 mm from 4.93 ± 1.73 mm in group P. By second-look arthroscopy, the graft and preserved remnant of each case was considered to have acceptable synovial coverage and to be taut.

CONCLUSIONS

The preserved ACL remnants possess acceptable morphology and the functions of anterior-posterior and rotational stability after surgery. Our procedure can be recommended for surgery on partial ACL tears.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Prospective analysis of failure rate and predictors of failure after anatomic anterior cruciate ligament reconstruction with allograft

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction is one of the most frequently performed orthopaedic procedures. Failures are a reality of surgery; to limit failures, we must first understand and quantify them.

PURPOSE

The purposes of this study were to determine the rate and factors associated with graft failure after anatomic ACL reconstruction performed with allograft.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All consecutive subjects who underwent anatomic single- or double-bundle ACL reconstruction with allograft between January 2007 and December 2009 were included and followed clinically. Graft failure was defined as patient-reported instability, pathological laxity during the physical examination, or evidence of a failed graft on magnetic resonance imaging or during arthroscopy. Potential predictors of graft failure that were explored included subject age, sex, height, weight, body mass index, meniscus injury, and time of return to preinjury sports.

RESULTS

There were 206 subjects included in this study: 168 double-bundle and 38 single-bundle reconstructions. Overall, 27 (13%) subjects experienced graft failure. Twenty-three (13%) double-bundle subjects failed. The characteristics associated with double-bundle graft failure were younger age (19 vs 25 years, P < .001) and earlier return to sports (at 222 vs 267 days, P = .007). Four (11%) of the single-bundle subjects failed. The characteristics associated with single-bundle graft failure were younger age (19 vs 24 years, P = .049) and increased body mass (83 vs 65 kg, P = .031).

CONCLUSION

The overall graft failure rate after anatomic ACL reconstruction with allograft was 13%. Younger age, earlier return to sports, and a higher body weight were associated with graft failure.

The effect of graft fixation angles on anteroposterior and rotational knee laxity in double-bundle anterior cruciate ligament reconstruction: evaluation using computerized navigation

BACKGROUND

One of the main differences affecting outcome between single-bundle and double-bundle anterior cruciate ligament (ACL) reconstructions may be graft fixation angles and initial force settings; however, there has been little research to investigate these effects in either technique.

HYPOTHESIS

Anteroposterior and rotational knee laxities will be less in double-bundle ACL reconstructions than single-bundle reconstructions, and different graft fixation angles affect knee kinematics and pivot-shift phenomenon in double-bundle ACL reconstructions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven patients who underwent double-bundle ACL reconstruction were included in this study. The anteromedial bundle (AMB) and the posterolateral bundle (PLB) were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB only at 20° (A20), (2) PLB only at 20° (P20), (3) AMB at 20° and PLB at 0° (A20P0), (4) AMB at 20° and PLB at 20° (A20P20), and (5) AMB at 20° and PLB at 45° (A20P45). All the grafts were tensioned at a constant stress level. Anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) at 30° and 90° of knee flexion applied with manual maximum load were measured before graft insertion and in each setting using a navigation system. A pivot-shift test was also evaluated manually with modified International Knee Documentation Committee criteria in each setting.

RESULTS

A20 was less constrained than A20P20 and A20P45 in ATT at 30° and less constrained than A20P45 in IR at 30°. P20 was less constrained than any other settings in ATT at 30° and less constrained than A20P45 in IR at 30°. A20P0 was less constrained than A20P45 in IR at 30° and in ER at 30°. Grade 1 pivot-shift phenomenon persisted in 8 cases in P20, in 4 cases in A20, and in 3 cases in A20P0, whereas no case showed a positive pivot-shift result in A20P20 and A20P45.

CONCLUSION

In this in vivo laboratory model, double-bundle ACL reconstruction with fixation of AMB at 20° and PLB at 20° or 45° restored better stability than single AMB or single PLB reconstruction in which the graft was of smaller size.

CLINICAL RELEVANCE

In double-bundle ACL reconstruction, fixation of the PLB at 0° might be looser and function worse compared with that of PLB at 20° or 45° when the AMB is fixed at 20°, with the individual variability that should lead to caution until it can be better assessed by surgeons.

Outcomes and second-look arthroscopic evaluation after double-bundle anterior cruciate ligament reconstruction with use of a single tibial tunnel

BACKGROUND

The correlation between graft appearance and clinical outcome after double-bundle anterior cruciate ligament (ACL) reconstruction is a major concern. In this study, the graft appearance was assessed with use of second-look arthroscopy and was correlated with the clinical outcome. Overall clinical outcomes after double-bundle ACL reconstruction with use of a single tibial tunnel were analyzed.

METHODS

Thirty-seven knees that underwent second-look arthroscopy after double-bundle ACL reconstruction and sixty-two knees that underwent double-bundle ACL reconstruction without subsequent second-look arthroscopy were included in this retrospective study. The ninety-nine patients enrolled were followed for thirty-five months (range, twenty-four to fifty-eight months), and the mean duration from ACL reconstruction to second-look arthroscopy was twenty-five months (range, twelve to thirty-six months). Graft thickness, apparent graft tension, and synovial coverage were graded during second-look arthroscopy. Correlations were sought between graft appearance and Lysholm knee scores, International Knee Documentation Committee (IKDC) grades, anterior laxity, and pivot-shift test results.

RESULTS

Postoperatively, ninety-four (94.9%) of the ninety-nine knees had an IKDC rating of B or higher, mean anterior laxity was 1.29 mm (range, 0 to 6 mm), and ninety-two knees (92.9%) had a negative pivot-shift result. With regard to graft thickness and tension, anteromedial bundles were graded as A in twenty-eight (75.7%) of the thirty-seven second-look knees and as B in nine knees (24.3%). Posterolateral bundles were graded as A in twenty-five knees (67.6%), B in six knees (16.2%), and C in six knees (16.2%). With regard to synovial coverage, anteromedial bundles were graded as C in only two knees (5.4%) and posterolateral bundles were graded as C in six knees (16.2%). No correlation was found between graft appearance and clinical outcome.

CONCLUSIONS

In the present study, we observed that clinical outcomes were as satisfactory with a single tibial tunnel as with two tibial tunnels. However, more tears and poorer synovial coverage were observed for posterolateral than for anteromedial bundles during second-look arthroscopy. No significant correlation was found between graft appearance and clinical outcome.

The Effect of Synovial Fluid Enzymes on the Biodegradability of Collagen and Fibrin Clots

Recently there has been a great deal of interest in the use of biomaterials to stimulate wound healing. This is largely due to their ability to centralize high concentrations of compounds known to promote wound healing at a needed location. Joints present a unique challenge to using scaffolds because of the presence of enzymes in synovial fluid which are known to degrade materials that would be stable in other parts of the body. The hypothesis of this study was that atelocollagen scaffolds would have greater resistance to enzymatic degradation than scaffolds made of gelatin, fibrin and whole blood. To test this hypothesis, collagen and fibrin-based scaffolds were placed in matrix metallopeptidase-1 (MMP-1), elastase, and plasmin solutions at physiologic concentrations, and the degradation of each scaffold was measured at varying time points. The atelocollagen scaffolds had a significantly greater resistance to degradation by MMP-1, elastase and plasmin over the fibrin based scaffolds. The results suggest that atelocollagen-based scaffolds may provide some protection against premature degradation by synovial fluid enzymes over fibrin-based matrices.

Relationship between thickness of the anteromedial bundle and thickness of the posterolateral bundle in the normal ACL

PURPOSE

Since the development of the anatomic double-bundle anterior cruciate ligament (ACL) reconstruction, many studies have focused on excursion and/or tension of each graft. However, no studies to date have adequately investigated thickness of the graft in anatomic double-bundle ACL reconstruction. To obtain basic knowledge from which an ideal graft thickness can be inferred, thicknesses of the anteromedial bundle (AMB) and posterolateral bundle (PLB) was measured in the normal ACL.

METHODS

The right knees of 50 cadavers donated for anatomy instruction were studied. Each ACL was separated into the AMB and PLB, and circumferences at the mid-substance and cross-sectional area at the femoral and tibial footprints were measured in each.

RESULTS

Cross-sectional areas of the AMB and PLB were 36 ± 10 and 32.1 ± 10.2 mm² at the femoral footprint, and 60.9 ± 21.8 and 52.2 ± 17.3 mm² at the tibial footprint, respectively. Circumferences at the mid-substance were 14.3 ± 3.3 mm for the ALB and 10.8 ± 3.1 mm for the PLB. A positive correlation was seen between AMB and PLB at each of the three sites.

CONCLUSION

The AMB is thicker than the PLB, showing a constant correlation in the normal ACL. This suggests that the anteromedial graft must be thicker than the posterolateral graft at least in actual operations.

Effects of different initial bundle tensioning strategies on the outcome of double-bundle ACL reconstruction: a cohort study

Background

This study was performed to investigate the effects of different strategies and initial tension applied to each one of the bundles, antero-medial (AM) and postero-lateral (PL), on clinical outcome in double bundle (DB) ACL reconstruction.

Methods

One hundred fifty-one primary unilateral DB ACL reconstructions performed by a single surgeon from 1994 through 2002 were included in the study with a follow-up of at least 24 months. They were divided in the following 3 groups: Group I - Higher initial tension applied manually in the AM bundle compared to PL. II - Higher tension applied in the PL bundle compared to AM. III - The 2 bundles were attempted to be equally tensioned. All fixations were performed in 30 degrees of flexion. Group I = 59 patients, group II = 53 patients and group III = 39 patients. The groups had no statistical differences concerning demographic distribution. Clinical outcome was retrospectively evaluated by use of knee range of motion, manual knee laxity tests, KT-1000, Lysholm knee scale, subjective recovery scale and sports performance recovery scale. The differences of data were analyzed among the three groups.

Results

Group I showed a significant extension deficit compared with groups II and III. ANOVA revealed a significant difference of anterior laxity measured by the KT-1000 (average KT difference of 2.1, 2.1 and 1.2 mm in Group I, II and III, respectively). A statistical difference was found among the three groups regarding subjective and sports performance recovery scales with Group II showing higher scores in recovery than Group I.

Conclusions

The current clinical study does not recommend manual maximum of initial tension applied to the anteromedial or posterolateral bundles with graft tension imbalance at 30 degrees of flexion in double-bundle ACL reconstruction to achieve a better clinical outcome.

Anatomic double-bundle anterior crucial ligament reconstruction with G-ST

The anterior cruciate ligament (ACL) consists of two primal functional bundles, anteromedial bundle and posterolateral bundles. Those two bundles play different functional roles and contribute differently to knee stability throughout the range of motion. Recent advancement in studies of anatomy and biomechanics of ACL has led surgeons to perform double-bundle ACL reconstruction to obtain better stability and kinematics. Consequently, variable surgical techniques of double-bundle ACL reconstruction have been reported to replicate native ACL. In addition, various surgical key points and problems in double-bundle ACL reconstruction techniques have also been reported. There has been a trend to more anatomically replicate native ACL bundles, not simply creating two bundles. We summarize the basic knowledge and current concepts of anatomic double-bundle ACL reconstruction using hamstrings tendons.

Biomechanical function of anterior cruciate ligament remnants: how long do they contribute to knee stability after injury in patients with complete tears?

PURPOSE

This study aimed to evaluate the biomechanical function of anterior cruciate ligament (ACL) remnants in anteroposterior and rotational knee stability in patients with a complete ACL injury.

METHODS

ACL remnants were classified into 5 morphologic patterns: group 1, bridging between the posterior cruciate ligament and tibia; group 2, bridging between the intercondylar notch and tibia; group 3, partial rupture of the posterolateral bundle; group 4, partial rupture of the anteromedial bundle; and group 5, no substantial ACL remnants. The decision of whether the remaining bundle represented partial or complete rupture of the ACL was made based on physical, magnetic resonance imaging, and arthroscopic findings in a comprehensive manner. Patients in groups 1 (n = 18) and 2 (n = 12) underwent intraoperative arthrometry with a navigation system before and immediately after resection of the ACL remnant. The effects of chronicity (duration between injury and surgery) and ACL remnant pattern on changes in knee laxity after debridement of the ACL remnant were investigated.

RESULTS

Chronicity had a significant effect on changes in anteroposterior knee laxity evaluated at 30° of knee flexion after resection of the ACL remnant (change in laxity of 2.22 mm for chronicity ≤1 year and 0.17 mm for chronicity >1 year). Chronicity did not influence changes in rotational knee stability after resection of the remnant. There were no significant differences between groups 1 and 2 with regard to any of the evaluated changes in knee stability.

CONCLUSIONS

In groups 1 and 2 ACL remnants contributed to anteroposterior knee stability evaluated at 30° of knee flexion for up to 1 year after injury, beyond which this biomechanical function was lost. Chronicity and remnant pattern did not influence changes in rotational knee stability after resection of the remnant.

LEVEL OF EVIDENCE

Level III, diagnostic study of nonconsecutive patients.

Radiographic findings in restrained hip joints associated with ACL rupture

Although decreased hip range of motion has been detected in many soccer players with noncontact anterior cruciate ligament (ACL), it is not clear whether it is associated with bone spurs, capsular soft tissue stiffness or both. Our aim was to investigate abnormal radiographic findings in soccer players with limited hip range of motion and noncontact ACL injury. Fifty consecutive male soccer players with restricted hip range of motion and noncontact ACL injury were subjected to radiographic examination to identify bone changes that could be associated with decreased hip range of motion. Of 50 patients, 56% revealed abnormal radiographic findings: pericapsular calcifications or acetabular rim osteophytes (24%), femoral neck deformity (10%), femoral neck and acetabular rim disorders (18%), neck groove caused by impingement (4%). Radiographic evaluation of those individuals showed a high number of bone abnormalities around the hip joint. This was considered to be an important finding to guide a decision-making process between three different approaches: changing the type of sports practiced, undergoing a more restrictive surgery (such as a double-bundle intra-articular reconstruction or an intra plus extra technique) or the onset of a hip-stretching program in addition to the conventional ACL rehabilitation protocol. In this last option, ACL-operated patients without radiographic hip abnormalities may have better outcomes for their decreased hip range of motion when submitted to a stretching program targeting the prevention of rotational overload on the reconstructed intra-articular grafts. The decision-making process concerning soccer players with ACL ruptures should take into consideration the amount of motion-limiting abnormalities around the hip joint.