Normal Anterior Cruciate Ligament Research Articles

Twenty-Year Experience of a Double-Bundle Anterior Cruciate Ligament Reconstruction.

Double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using a four-strand semitendinosus tendon was started in our department in July 1994. The motivation for starting the procedure was that the EndoButton with an inside-out procedure instrument became available in Japan. A review article of our DB ACL reconstruction procedure was summarized for the twentieth anniversary of the surgical procedure. Initial tension setting of the two grafts was changed in the first 8 years to achieve better stability during DB ACL reconstruction. A randomized clinical trial (RCT) was started in July 2002 to clarify superiority of the DB procedure to single-bundle (SB) reconstruction under the concept of anatomic reconstruction. Several anatomic studies were performed to describe normal ACL anatomy, which is essential for realizing anatomic reconstruction. A remnant-preserving technique would be an additional option for our DB procedure to improve reconstruction outcomes. Thus, a new remnant-preserving DB procedure was started in 2012. The reproducibility of the new procedure was investigated using three-dimensional computed tomography images. More complex procedures were performed using a transtibial technique and EndoButtons. Initial tension balancing between the two grafts was important for a better outcome. Superiority of knee stability after the DB compared to that after the SB procedure was clarified by the RCT. However, no patient consensus has been reached on any subjective advantage to the DB procedure. Studies of normal ACL anatomy have left questions unresolved regarding where the two tunnels should be created for direct and indirect insertions based on normal anatomy. A new remnant-preserving DB ACL procedure has been practiced. The procedure was more reproducible with respect to creating the femoral tunnel. DB ACL reconstruction using a semitendinosus tendon is an attractive option when pursuing a better outcome for patients.

Radiographic (magnetic resonance) evaluation of the anteromedial versus the transtibial technique in anterior cruciate ligament reconstruction

Purpose: Making the femoral tunnel through the anteromedial (AM) portal is believed to allow an unconstrained position compared with the traditional transtibial (TT) tunnel. Our aim was to compare the AM and TT portals during anterior cruciate ligament (ACL) reconstruction using magnetic resonance imaging (MRI) to identify the three-dimensional (3D) position of the ACL and compare it to the normal ACL. Materials and Methods: The literature was reviewed to identify the angles used for comparison. A case-control study was conducted with AM, TT and control groups. MRI was used to measure the sagittal ACL angle (angle A), the Blumensaat angle (angle B), and the coronal ACL angle (angle C) in the three groups. Results: The sum of squares and mean squares of the angles were used. A comparison of the AM and control groups (A vs. C) showed a P value of 0.417, whereas the P value for the control and TT groups (C vs. T) was 0.001. The P values for the two comparisons with angle C were significant (P = 0.0007 and

Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) tears constitute the most common ligamentous injury in the knee. Surgical options for the restoration of the mechanical function of the ACL include primary repair, or ACL graft reconstruction. Primary repair is useful for cases of tibial avulsion of the ACL. MRI is the modality of choice for the evaluation of graft integrity. Potential complications are demonstrated optimally with MRI. A clear knowledge of the imaging appearance of the normal ACL graft is essential for the accurate assessment of possible complications after ACL graft reconstruction.

Comparison of Pull-out Strength for Different Bone Block Length in a Porcine Anterior Cruciate Ligament Model.

Background:Bone block length for bone–patellar tendon–bone (BPTB) anterior cruciate ligament (ACL) reconstruction has traditionally been 25 mm in length. The previous surgical technique did not require the surgeon to pay particular attention to the length of the bone block, and therefore, there is scant evidence in the literature describing ideal lengths. With the gaining popularity of accessory medial portal drilling of the femoral tunnel, concerns with tunnel length and graft shuttling have surfaced. Newer techniques have advised shortening of the femoral bone block to accommodate the shorter tunnel and for ease of bone block manipulation into the aperture of the tunnel.Purpose:To compare the effects of bone block length on the pull-out strength of patellar tendon grafts using metal interference screws in a porcine ACL reconstruction model. The hypothesis was that the pull-out strength of each length of bone block under cyclic and ultimate load to failure testing would surpass the physiologic loads experienced by a normal ACL.Study Design:Controlled laboratory study.Methods:This study used 27 unmatched porcine femurs and BPTB constructs. Specimens were randomly assigned to a 10-, 15-, or 20-mm bone block reconstruction and a cycle load of 100, 500, or 1000 cycles. This resulted in 9 specimen groups with 3 specimens in each group. A central composite design (CCD) for the test matrix was selected, as this was optimum for requiring relatively few experiments while still exploring the complete range of interest for 2 independent variables. Each reconstruction used a 7 × 20–mm titanium interference screw. All reconstructions were performed on the femoral side using 10-mm-wide patellar tendon grafts, and tensile tests were performed. The loading protocol started with a 20-N preload, then cyclic testing to the appropriate number of cycles in the elastic region between 50 and 150 N at a strain rate of 200 mm/min, and then ended with ultimate load-to-failure testing. Ultimate load to failure, peak stress, elongation, and stiffness were all recorded. The patellar tendon graft mode of failure was measured by visual inspection.Results:During load-to-failure testing, 5 of 9 graft constructs in the 10-mm group failed at the bone block, while 2 of 9 failed in the 15-mm group at this interface. In the 20-mm group, all 9 specimens failed at the tendon, and none failed at the bone block. There was a statistically significant difference in modes of failure between the bone block length groups in the reconstructed ACL grafts. Analysis indicates that a smaller bone block length graft is more likely to fail due to a bone block failure than a tendon failure. The average ± standard deviation failure load for all specimens was 573 ± 171 N. The mean failure loads for the 10-, 15-, and 20-mm groups were 614 ± 110, 658 ± 92, and 540 ± 203 N, respectively. There was no statistical significance between the groups in any of these measurements.Conclusion:Bone blocks of 20 to 25 mm in length are normally used in surgical practice. Thus, the purpose of this study was to explore the effects of a smaller bone block length in the fixation strength of a graft. This study could not yield a significant difference in failure load for differently sized bone blocks. There was a significant tendency of shorter bone block lengths to fail due to bone block failure.Clinical Relevance:Bone block failure was defined as slippage of the bone block or interference screw. These results show that using a smaller bone block may increase the likelihood of a graft failure in an ACL reconstruction.

Outcome of anatomical double-bundle ACL reconstruction using hamstring tendons via an outside-in approach

To evaluate the clinical outcome of anatomical double-bundle anterior cruciate ligament (ACL) reconstruction using multistranded hamstring tendons via an outside-in approach. One hundred and twenty-one patients (mean age 28±10years) who underwent ACL reconstruction were examined. Using an outside-in femoral drill guide, an upper femoral tunnel for the anteromedial (AM) graft was created just below the superior articular cartilage margin of the medial wall of the lateral condyle through a small incision. A lower femoral tunnel for the posterolateral (PL) graft was drilled in the centre of the inferior-posterior half of the attachment area behind the resident's ridge in the same manner. Two tibial tunnels were created at the centre of the AM and PL bundle footprints of a normal ACL. Patients were evaluated at 24months postoperatively. According to the IKDC form, 52 knees (43%) were graded as normal, 64 (53%) as nearly normal, 1 (1%) as abnormal and 4 (3%) as graft rupture due to re-injury. Loss of knee extension of <5° was observed in one patient (1%). Among 111 patients who were directly evaluated, none showed loss of flexion of <5°. Lachman sign was negative in 103 patients (93%), while the pivot shift test result was negative or equivalent to that of the contralateral healthy knee in 103 patients (93%). The mean side-to-side difference in anterior laxity at manual maximum force with the KT-2000 arthrometer(®) was 0.9±1.1mm, and 94% of patients showed a range between -1 and +2mm. The anatomical double-bundle outside-in ACL reconstruction provided a satisfactory short-term outcome. Case series, Level IV.

Optimal Parameters for Sutures Tied to a Post during Anterior Cruciate Ligament Reconstruction: Thread Numbers, Knot Numbers, Suture Techniques and Stitch Numbers: An Experimental Laboratory Study Using Porcine Tendon

We evaluated the conditions required for sutures tied to a post for tibial fixation during anterior cruciate ligament (ACL) reconstruction. Harvested porcine tendon was used as a graft material and nonabsorbable suture was used for sutures. Samples were tested for ultimate tensile load and elongation according to thread numbers, knot numbers, suture techniques and stitch numbers. As thread numbers were increased, ultimate tensile load was increased and elongation was decreased. However, more than 4 strands of threads provided the sufficient ultimate tensile load more than 454 N of normal ACL for daily activities. As knot numbers were increased, ultimate tensile load was increased, but elongation was decreased. In terms of failure mode, unraveling occurred 100% in 3 and 4 knots, 81.2% in 5 knots, 54.5% in 6 knots, and 0% in 7 knots. Suture techniques and stitch numbers didn’t significantly affect the ultimate tensile load and the elongation. For sutures tied to a post for tibial fixation in ACL reconstruction, more than 4 threads, more than 7 knots, and more than 4 stitches provide adequate ultimate tensile load and elongation.

Use of a strontium-enriched calcium phosphate cement in accelerating the healing of soft-tissue tendon graft within the bone tunnel in a rabbit model of anterior cruciate ligament reconstruction

We investigated whether strontium-enriched calcium phosphate cement (Sr-CPC)-treated soft-tissue tendon graft results in accelerated healing within the bone tunnel in reconstruction of the anterior cruciate ligament (ACL). A total of 30 single-bundle ACL reconstructions using tendo Achillis allograft were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, whereas that on the contralateral limb was untreated and served as a control. At timepoints three, six, nine, 12 and 24 weeks after surgery, three animals were killed for histological examination. At six weeks, the graft-bone interface in the control group was filled in with fibrovascular tissue. However, the gap in the Sr-CPC group had already been completely filled in with new bone, and there was evidence of the early formation of Sharpey fibres. At 24 weeks, remodelling into a normal ACL-bone-like insertion was found in the Sr-CPC group. Coating of Sr-CPC on soft tissue tendon allograft leads to accelerated graft healing within the bone tunnel in a rabbit model of ACL reconstruction using Achilles tendon allograft.

Biological and Biomechanical Evaluation of the Ligament Advanced Reinforcement System (LARS AC) in a Sheep Model of Anterior Cruciate Ligament Replacement: A 3-Month and 12-Month Study

The purposes of this study were to assess tissue ingrowth within the Ligament Advanced Reinforcement System (LARS) artificial ligament (LARS AC; LARS, Arc sur Tille, France) and to study the biomechanical characteristics of the reconstructed knees in a sheep model of anterior cruciate ligament (ACL) replacement. Twenty-five female sheep underwent excision of the proximal third of the left ACL and intra-articular joint stabilization with a 44-strand polyethylene terephthalate ligament (mean ultimate tensile failure load, 2,500 N). Animals were killed either 3 or 12months after surgery. Explanted knees were processed for histology (n= 10) or mechanical tests including tests of laxity and loading to failure in tension (n= 15). Well-vascularized tissue ingrowth within the artificial ligament was only observed in the portions of the ligament in contact with the host's tissues (native ligament and bone tunnels). Ligament wear was observed in 40% of explanted knees. The ultimate tensile failure loads of the operated knees at both time points were inferior to those of the contralateral, intact knees (144 ± 69 N at 3 months and 260 ± 126 N at 12 months versus 1,241 ± 270 N and 1,218 ± 189 N, respectively) (P < .01). In specimens with intact artificial ligaments, failure occurred by slippage from the bone tunnels in all specimens explanted 3 months postoperatively and in half of the specimens explanted 12 months postoperatively. This study provides evidence that the LARS AC has a satisfactory biointegration but that it is not suitable for ACL replacement if uniform tissue ingrowth is contemplated. Despite good clinical performance up to 1 year after implantation, none of the reconstructions approached the mechanical performance of the normal ACL in the ovine model. Partial tearing of the artificial ligament, which led to a significant decrease in ultimate tensile strength, was observed in 40% of cases in the ovine model. The LARS is not a suitable scaffold for ACL replacement. Further animal studies are needed to evaluate its potential for augmentation of ligament repair.

Optimal Graft Length for Anterior Cruciate Ligament Reconstruction: A Biomechanical Study in Beagles

The anterior cruciate ligament (ACL) is a major ligament that helps maintain the stability of the knee joint. Injury to the ACL can be treated by replacing the torn ligament. This study determined the optimal flexor tendon length in the bone tunnel in ACL reconstruction.Autologous ACL reconstruction was performed using a flexor tendon in 54 male beagles, with the graft length in the bone tunnel at 5, 9, 13, 17, 21, and 25 mm (9 dogs per graft length). The maximum tensile strength and stiffness of the reconstructed joint (tibia-ACL-femur triad) were recorded at 45, 90, and 180 days after ACL reconstruction (6 joints per time point). The experiment also included an intact control group (3 dogs) and a control group tested immediately after the reconstruction (3 dogs). For the intact control group, the normal ACL (unreconstructed) and flexor tendon mechanical testing was performed. For the other control group, the normal ACL (unreconstructed) mechanical testing was performed first and then mechanical testing of the specimens was performed immediately after reconstruction. The maximum tensile strength and stiffness of the reconstructed tibia-ACL-femur triad increased with time after reconstruction, regardless of the graft length in the bone tunnel. Maximum tensile strength and stiffness of the grafts increased with graft length but reached a plateau at 17 mm. Optimal strength and stiffness of the reconstructed ACL are achieved with 17-mm grafts.

Sensitivity and specificity of bell-hammer tear as an indirect sign of partial anterior cruciate ligament rupture on magnetic resonance imaging

The main purpose of this study was to evaluate the usefulness of the bell-hammer sign in the diagnosis of partial tears of the anterior cruciate ligament (ACL) of the knee on MRI. A retrospective study was performed including all patients who underwent ACL reconstruction for partial or complete tears from 2008 to 2009. The diagnosis of partial or complete ACL tears was based on the appearance of the ligament bundles and the signal quality on MRI. On arthroscopy, which is considered the gold standard, each bundle was classified as normal, partially or completely torn depending on the extent of the rupture and the quality of the remaining fibres. The study included 312 patients, 83 women and 229 men (mean age 33.3 ± 19.6 years). A diagnosis of a tear was made in all patients on preoperative MRI. Arthroscopy did not show any normal ACL, 247/312 (79.2 %) complete tears and 65/312 (20.8%) partial tears, 50/65 (76.9%) on the anteromedial bundle (AM) and 15/65 (23.1%) the posterolateral bundle. The bell-hammer sign was found on MRI in 13/312 patients (4.5%). It involved 9/65 (13.8%) partial tears, all in the AM bundle, and 4/247 (1.6%) complete tears, significantly more frequent in cases of partial rupture (p < 0.0001). MRI diagnosed a partial tear in 15/65 cases without the bell-hammer sign (sensitivity CI 95% = 23.1 ± 10%, specificity CI 95% = 95.9 ± 2.5%) and with the bell-hammer sign in 23/65 cases (sensitivity CI 95% = 35.4 ± 11%, specificity CI 95% = 93.9 ± 3%). The association of the bell-hammer sign with conventional radiological diagnostic criteria has improved diagnosis performance of MRI for partial tears but not significantly (ns). The most important interest of the bell-hammer sign in the day-to-day clinical work is to suggest partial tears on MRI. It aids making a diagnosis, but its absence does not exclude partial ACL rupture. Diagnostic study, Level II.

Possibility of natural healing to anterior cruciate ligament tear

An acute tear of the ligament generally heals conservatively. Whereas, it is thought that the tear of the anterior cruciate ligament (ACL) does not heal by the conservative treatment. There are many studies about the factors that ACL does not heal conservatively.The purpose of the research was to create a rat model of natural healing of ACL and to examine the healed ligament histologically and mechanically.After cutting ACL, the artificial ligament was penetrated the bone tunnel of tibia tuberosity and back of the distal femur, and controlled the abnormal movement of the knee joint. We had confirmed the continuity of the healed ACL in all rats with histological evaluation. Running of the healing ligament had been normally approximated. Compared to the normal ACL, the healing ligament was thick, and scar tissue had grown into joint intercondylar fossa. Healing ACL was about half strength compared to the normal.We found that the ruptured anterior cruciate ligament was healed by joint control kinematically.

Anterior cruciate ligament regeneration using mesenchymal stem cells and collagen type I scaffold in a rabbit model

The objective of this study was to determine whether using mesenchymal stem cells (MSC) seeded in a collagen type I scaffold would be sufficient to regenerate the torn anterior cruciate ligament (ACL). Anterior cruciate ligament transection was performed on both knees in 10 New Zealand rabbits and then repaired with as follows: suture alone (suture-treated group, n = 6), suture associated with collagen type I scaffold (collagen type I scaffold-treated group, n = 8) or suture associated with autologous MSC seeded on collagen type I scaffold (MSC/collagen type I scaffold-treated group, n = 6). At 12-week post-intervention, the animals were killed and the ACLs were characterised macroscopically and histologically. Data of the 3 groups were against normal ACL (normal group, n = 10). Macroscopic observation found that in MSC/collagen type I scaffold group, 33% of specimens showed a complete ACL regeneration, with a tissue similar to the normal ACL. Regeneration was not observed in the group treated with suture alone or associated with collagen type I scaffold without cells. In the latter, only a reparative attempt at the ends was observed. Histological analysis of the regenerated ACL showed a tissue with organised collagen and peripheric vessels. These results provide evidence that the use of MSC seeded in a collagen type I scaffold in the treatment of ACL injuries is associated with an enhancement of ligament regeneration. This MSC-based technique is a potentially attractive tool for improving the treatment of ACL ruptures.

Sonography of the Normal Anterior Cruciate Ligament: A Preliminary Report

Currently, sonography is not used routinely for the evaluation of anterior cruciate ligaments (ACLs). The purpose of this study is to show that sonography can be used to directly evaluate the ACL. A normal individual and a patient with a chronic left ACL tear that was not repaired underwent magnetic resonance imaging (MRI) and sonographic examination in a 90° knee flexion position. A 7–9 MHz linear ultrasound transducer was used to obtain sonographic images at the infra-patellar region. We subsequently compared the MRI and sonographic images to define the ACL images. We proved our hypothesis by using a Kelley to pinpoint the ACL during the arthroscopic examination of a knee with normal ACL. Thirty-three normal right knees in 33 individuals also received sonographic examination for confirmation of our study. The ACL appeared as a hypoechoic band attached 11.00 ± 1.24 mm perpendicularly inferior to the tibia plateau. Its mean diameter was 8.30 ± 1.46 mm.

The pattern of cartilage damage in antero‐medial osteoarthritis of the knee and its relationship to the anterior cruciate ligament

Within antero-medial gonarthrosis (AMG) of the knee, there is a spectrum of damage seen in the functionally intact anterior cruciate ligament (ACL). Our aim was to correlate the degree of ACL damage to the geographical extent and degree of cartilage loss on the tibial plateau. Ninety tibial plateaus resected during unicompartmental arthroplasty were photographed and digitally mapped. The ACL damage was graded (0: normal, 1: synovium loss, 2: longitudinal splits), and dimensions of full thickness cartilage loss and damage recorded. The percentage of full thickness loss in patients with a normal ACL was compared to those with a damaged, but functionally intact ligament. All specimens showed similar elliptical loss of cartilage in the antero-medial part of the tibial plateau. A total of 45(50%) patients had a macroscopically normal ACL, 21(23%) had synovial loss, and 24(27%) had longitudinal splits. An increase in the area of cartilage damage was seen with progressive ACL damage (p < 0.001). The area of macroscopically normal cartilage found posteriorly did not change. This study demonstrates that phenotypic distribution of cartilage damage in AMG is highly reproducible with a pattern of increasing cartilage erosion associated with increasing ACL damage.

Measurement of normal patellar ligament and anterior cruciate ligament by MRI and data analysis

The aim of this study was to obtain geometric data of in vivo patellar ligament (PL) and anterior cruciate ligament (ACL) by MRI and to analyze the correlation of the two with body weight, height and gender. A total of 157 cases with normal sagittal images of bilateral PL and ACL were enrolled. The PL and ACL lengths in the images were measured using the Radworks 5.1 application. The intraclass correlation coefficient for the data measured independently by three doctors was 0.997–1.000. In individuals aged 15–24 years, the values of PL and ACL length and the PL to ACL ratio were 43.95±4.25 mm, 38.45±4.62 mm and 1.15±1.09 in males and 42.03±0.94 mm, 36.00±1.06 mm and 1.18±0.1 in females, respectively. In individuals aged 25–64 years, the values in males were 40.99±4.45 mm, 36.06±3.74 mm and 1.14±0.09 and in females were 39.84±0.64 mm, 36.50±0.81 mm and 1.11±0.02, respectively. In individuals aged ≥65 years, the values in males were 41.43±3.08 mm, 36.62±3.44 mm and 1.15±0.09 and in females were 38.94±0.79 mm, 34.36±0.85 mm and 1.13±0.07, respectively. There was a significant difference between PL and ACL length on the same side (P<0.01). The data obtained was stable and repeatable. The present study established a database of PL and ACL length and the ratio of the two measured by MRI.

Cellular and extracellular matrix changes in anterior cruciate ligaments during human knee aging and osteoarthritis

IntroductionAnterior cruciate ligament (ACL) degeneration is observed in most osteoarthritis (OA)-affected knee joints. However, the specific spatial and temporal relations of these changes and their association with extracellular matrix (ECM) degeneration are not well understood. The objective of this study was to characterize the patterns and relations of aging-related and OA-associated changes in ACL cells and the ECM.MethodsHuman knee joints from 80 donors (age 23 through 94) were obtained at autopsy. ACL degeneration was assessed histologically by using a quantitative scoring system. Tissue sections were analyzed for cell density, cell organization, ECM components, ECM-degrading enzymes and markers of differentiation, proliferation, and stem cells.ResultsTotal cell number in normal ACL decreased with aging but increased in degenerated ACL, because of the formation of perivascular cell aggregates and islands of chondrocyte-like cells. Matrix metalloproteinase (MMP)-1, -3, and -13 expression was reduced in aging ACL but increased in degenerated ACL, mainly in the chondrocyte-like cells. Collagen I was expressed throughout normal and degenerated ACL. Collagen II and X were detected only in the areas with chondroid metaplasia, which also expressed collagen III. Sox9, Runt-related transcription factor 2 (Runx2), and scleraxis expression was increased in the chondrocyte-like cells in degenerated ACL. Alpha-smooth muscle actin (α-SMA), a marker of myofibroblasts and the progenitor cell marker STRO-1, decreased with aging in normal ACL. In degenerated ACL, the new cell aggregates were positive for α-SMA and STRO-1.ConclusionsACL aging is characterized by reduced cell density and activation. In contrast, ACL degeneration is associated with cell recruitment or proliferation, including progenitor cells or myofibroblasts. Abnormally differentiated chondrocyte-like cell aggregates in degenerated ACL produce abnormal ECM and may predispose to mechanical failure.

Long-term results after reconstruction of the ACL with hamstrings autograft and transtibial femoral drilling

To evaluate the long-term clinical, patient-reported and radiological outcome of patients reconstructed for anterior cruciate ligament (ACL) insufficiency. We wanted to examine the relationship between clinical findings and patient-reported scores. The 96 first successive patients that underwent ACL reconstruction using transtibial technique, hamstrings autograft and tunnel placement ad modum Howell were evaluated 10 years post-operatively. Subjective outcomes were Lysholm score, IKDC 2000 subjective score and Tegner activity scale. The clinical examination included evaluation of rotational and sagittal laxity. Evaluation of osteoarthritis was done radiologically. Eighty-three patients (86%) were available for follow-up at mean 10.2 years post-operatively. Three patients had revision ACL surgery prior to the 10-year evaluation. The mean Lysholm score, subjective IKDC 2000 score and Tegner activity scale were 89 (SD 13), 83 (SD 15) and 5 (range, 3-9), respectively. Six patients (8%) had moderate or severe osteoarthritis. Eighty-six per cent of patients had normal or near-normal anterior-posterior ACL laxity. Twenty per cent of patients had positive pivot shift and 42 % had a pivot glide. The former group had a significant lower Lysholm score compared to the rest of the patients. Although the mean Lysholm score was classified as good (89) at the 10-year follow-up, a positive pivot shift was found in 20% of these patients. Compared to patients with normal rotational laxity or pivot glide, this patient group reported significant lower subjective satisfaction at the long-term follow-up. Case series, level IV.

Partial tears of the anterior cruciate ligament: diagnostic performance of isotropic three-dimensional fast spin echo (3D-FSE-Cube) MRI

To compare the performance of 3D-FSE-Cube MRI to arthroscopy, the reference test for the diagnosis of partial anterior cruciate ligament (ACL) tears. A retrospective study was performed including all patients who underwent surgery for an ACL tear in our Sports Surgery Unit from January 2008 to December 2009. All patients underwent a preoperative MRI, conventional 2D or 3D-Cube. The diagnosis of a partial tear was based on the appearance of the ligament bundles and signal quality on MRI, and on the continuity of the fibers on arthroscopy and the quality of the remaining ligament. Sixty-four of the 312 included patients underwent MRI 3D-Cube and 248 conventional 2D-MRI. The series included 82 women and 223 men, mean age 33.3 ± 19.6 years. Arthroscopy did not reveal any normal ACL, 247/312 (79.2 %) complete tears, and 65/312 (20.8 %) partial tears, with 50/65 (76.9 %) involving the anteromedial bundle and 15/65 (23.1 %) the posterolateral. The results of MRI 3D-Cube were as follows: sensitivity 95 % CI = 62.5 ± 23.7 %, specificity 95 % CI = 93.7 ± 6.9 %, likelihood ratio LR(+) = 9.9, LR(-) = 0.4 and accuracy 85.9 %. Results of conventional 2D-MRI were as follows: sensitivity 95 % CI = 10.2 ± 8.5 %, specificity 95 % CI = 96.5 ± 2.5 %, LR(+) = 2.9, LR(-) = 0.9 and accuracy 79.4 %. The diagnostic performance of MRI 3D-Cube was better than conventional 2D-MRI. The diagnostic performance of MRI 3D-Cube in partial ACL tears was good and significantly better than conventional 2D-MRI. The likelihood of having a positive test was 9.9 times higher in a patient with a partial tear. A negative result did not exclude this diagnosis.

Differential expressions of lysyl oxidase family in ACL and MCL fibroblasts after mechanical injury

Lysyl oxidase (LOX) family has the capacity to catalyse the cross-linking of collagen and elastin, implicating its important fundamental roles in tissue development and injury healing. However, the variations in expression of the LOX family in the normal and injured anterior cruciate ligament (ACL) are not fully known. To better understand the role of LOX family in the self-healing inability mechanism of injured ACL, this study is to measure the LOX family's differential expressions in ACL and medial collateral ligament (MCL) fibroblasts after mechanical injury induced by using an equi-biaxial stretching chamber. The cells received various degrees of mechanical stretch 0% (resting state), 6% (physiological state) and 12% (injurious state), respectively. The gene profile and protein expressions were analysed by semi-quantitative PCR, quantitative real-time PCR and Western blotting. At physiological state, gene expression showed LOX in ACL was 2.6–5.2 folds higher than that in MCL in all culture time periods, LOXL-4 1.2–3.6 folds, but LOXL-3 in MCL showed 1.1–4.8 folds higher than that in ACL. In injurious state, MCL gene expressions were 2.8–29.6 folds higher than ACL in LOX, LOXL-2, LOXL-3 and LOXL-4 at 2, 6 and 12h periods. These differential expression profiles of the LOX family in the two ligament tissues were further used to explain the intrinsic differences between ACL and MCL, and why injured ACL could not be amenable to repair itself, whereas MCL could.

Paper 14: Magnetic Resonance Imaging Measurement of the Two Bundles of the Normal Anterior Cruciate Ligament

Paper 14: Magnetic Resonance Imaging Measurement of the Two Bundles of the Normal Anterior Cruciate Ligament