Intact Knee Research Articles

The relationship between patellar lateralization diagnostic imaging markers and non-contact internal knee derangements

BackgroundTo investigate differences in the tibial tubercle-trochlear groove (TT-TG) and patellar tendon-posterior cruciate ligament (PT-PCL) distances in symptomatic patients with non-contact internal knee derangements (IKD) and symptomatic patients with internally intact knees (control).MethodsA retrospective review of MRI studies was completed by comparing 78 patients with meniscal and ligamentous derangements of the knee to 63 internally intact knees (age range, 13 to 50 years). MRI findings were reviewed independently by two board-certified radiologists to assess for agreement. TT-TG and PT-PCL distances were measured on proton density-weighted axial images by two independent observers blinded to the MRI and arthroscopic findings. Independent t tests were used to determine differences in TT-TG distance between the internal derangement and control groups. Chi-square tests were used to compare categorical variables for distributional equality between study groups.ResultsThe mean TT-TG distance averaged across the two raters in the IKD group was 11.5 mm (95% confidence interval [CI], 10.6–12.4), compared to 8.3 mm (95% CI, 7.6–9.0) in the control group (p < 0.001). The mean PT-PCL distance similarly averaged across both raters was 20.6 mm (95% CI, 19.7–21.5) for the IKD group compared to 18.2 mm (95% CI, 17.2–19.2) for the control group (p < 0.001). Among the IKD group, there were 51 meniscal tears, 12 cruciate ligament tears, and 15 tears with a combination of meniscal and cruciate findings. IKD was significantly correlated with greater TT-TG distance (p < 0.001) and greater PT-PCL distance (p < 0.003) when compared with control.ConclusionsIncreased TT-TG distances and PT-PCL distances are associated with both cartilaginous and ligamentous internal knee injuries in the present study, with TT-TG distances greater than the 12 mm representing a new threshold for concern.

A constrained-condylar fixed-bearing total knee arthroplasty is stabilised by the medial soft tissues

PurposeRevision constrained-condylar total knee arthroplasty (CCK-TKA) is often used to provide additional mechanical constraint after failure of a primary TKA. However, it is unknown how much this translates to a reliance on soft-tissue support. The aim of this study was therefore to compare the laxity of a native knee to the CCK-TKA implanted state and quantify how medial soft-tissues stabilise the knee following CCK-TKA.MethodsTen intact cadaveric knees were tested in a robotic system at 0°, 30°, 60° and 90° flexion with ± 90 N anterior–posterior force, ± 8 Nm varus-valgus and ± 5 Nm internal–external torques. A fixed-bearing CCK-TKA was implanted and the laxity tests were repeated with the soft tissues intact and after sequential cutting. The deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) were sequentially transected and the percentage contributions of each structure to restraining the applied loads were calculated.ResultsImplanting a CCK-TKA did not alter anterior–posterior laxity from that of the original native knee, but it significantly decreased internal–external and varus-valgus rotational laxity (p < 0.05). Post CCK-TKA, the sMCL restrained 34% of the tibial displacing load in anterior drawer, 16% in internal rotation, 17% in external rotation and 53% in valgus, across the flexion angles tested. The dMCL restrained 11% of the valgus rotation moment.ConclusionsWith a fully-competent sMCL in-vitro, a fixed-bearing CCK-TKA knee provided more rotational constraint than the native knee. The robotic test data showed that both the soft-tissues and the semi-constrained implant restrained rotational knee laxity. Therefore, in clinical practice, a fixed-bearing CCK-TKA knee could be indicated for use in a knee with lax, less-competent medial soft tissues.Level of evidenceControlled laboratory study.

An MRI-compatible varus\u2013valgus loading device for whole-knee joint functionality assessment based on compartmental compression: a proof-of-concept study

ObjectiveBeyond static assessment, functional techniques are increasingly applied in magnetic resonance imaging (MRI) studies. Stress MRI techniques bring together MRI and mechanical loading to study knee joint and tissue functionality, yet prototypical axial compressive loading devices are bulky and complex to operate. This study aimed to design and validate an MRI-compatible pressure-controlled varus–valgus loading device that applies loading along the joint line.MethodsFollowing the device’s thorough validation, we demonstrated proof of concept by subjecting a structurally intact human cadaveric knee joint to serial imaging in unloaded and loaded configurations, i.e. to varus and valgus loading at 7.5 kPa (= 73.5 N), 15 kPa (= 147.1 N), and 22.5 kPa (= 220.6 N). Following clinical standard (PDw fs) and high-resolution 3D water-selective cartilage (WATSc) sequences, we performed manual segmentations and computations of morphometric cartilage measures. We used CT and radiography (to quantify joint space widths) and histology and biomechanics (to assess tissue quality) as references.ResultsWe found (sub)regional decreases in cartilage volume, thickness, and mean joint space widths reflective of areal pressurization of the medial and lateral femorotibial compartments.DiscussionOnce substantiated by larger sample sizes, varus–valgus loading may provide a powerful alternative stress MRI technique.

Contact mechanics after mattress suture repair of medial meniscus vertical longitudinal tear: an in vitro study.

Most studies have concentrated on the changes in contact pressure and area on the tibiofemoral joint. This study compared the contact mechanics underneath the medial meniscus of a repaired vertical longitudinal tear with that of the intact or the torn ones. In this controlled laboratory study, a 1000 N compressive axial load was applied to eight fresh-frozen cadaveric knees at four flexion angles and four loading conditions using a custom testing apparatus attached to a material testing machine. Intact knees, knees with a medial meniscus vertical longitudinal tear, and knees after meniscal repair were tested. The peak contact pressure and area underneath the meniscus were measured using Fuji pressure-sensitive film. A medial meniscus vertical longitudinal tear significantly increased the contact pressure and decreased contact area underneath the meniscus compared with those at the intact meniscus under all tested biomechanical conditions, and repair of the tear can restore the contact pressure and area in most conditions. While the repaired group showed a significantly higher or similar contact pressure compared with the tear group at 90° neutral knee position and at 60°, 90° 5 N·m-external rotation and 134 N-anterior tibial translation, and 5 N·m-internal rotation at all flexion angles. The contact area corresponding to the aberrant result of the contact pressure in the repaired group was lower than in the intact meniscus group. The contact mechanics underneath the meniscus of the repaired medial meniscus vertical longitudinal tear were significantly improved compared with the corresponding tear conditions in most cases, while the contact pressure and area at some certain status after repair were not significantly different from those of the corresponding tear conditions.

Reduction of in situ force through the meniscus with phased inner resection of medial meniscus: an experimental study in a porcine model

PurposePartial meniscectomy can cause osteoarthritic changes in knees, as inner portion as well as peripheral portion of meniscus is important. The hypothesis of this study was that the amount of the inner resection of medial meniscus affected the in situ forces through the meniscus and the tibial varus and external rotation under axial load.MethodsFourteen intact porcine knees were investigated with a six-degree of freedom robotic system and force/moment, and the three-dimensional path of intact knees were recorded by universal force sensor when an axial load of 300-N was applied at four different flexion angles (30°, 60°, 90°, and 120°). The same examination was performed on three phased inner resections (30%, 60%, and 90% width) of the medial meniscus. Finally, all paths were reproduced after total medial meniscectomy, and in situ forces of the medial meniscus were calculated based on the superposition principle. Changes in tibiofemoral varus/valgus and internal/external rotation alignment during an axial load were also calculated.ResultsIn situ forces of the medial meniscus decreased according to the amount of meniscal resection at all flexion angles. The reduction was significant in knees with inner resections of > 60% width at all flexion angles and even of 30% width at a flexion angle of 120° (p < .05). Incremental changes in the tibiofemoral varus alignment increased depending on the inner resection width at all flexion angles (p < .05).ConclusionThe amount of inner resection of the medial meniscus was related to reduction of its in situ forces and increment of the tibial varus rotation under axial load.

The implications of non-anatomical positioning of a meniscus prosthesis on predicted human knee joint biomechanics

Despite all the efforts to optimize the meniscus prosthesis system (geometry, material, and fixation type), the success of the prosthesis in clinical practice will depend on surgical factors such as intra-operative positioning of the prosthesis. In this study, the aim was therefore to assess the implications of positional changes of the medial meniscus prosthesis for knee biomechanics. A detailed validated finite element (FE) model of human intact and meniscal implanted knees was developed based on a series of in vitro experiments. Different non-anatomical prosthesis positions were applied in the FE model, and the biomechanical response during the gait stance phase compared with an anatomically positioned prosthesis, as well as meniscectomized and also the intact knee model. The results showed that an anatomical positioning of the medial meniscus prosthesis could better recover the intact knee biomechanics, while a non-anatomical positioning of the prosthesis to a limited extent alters the knee kinematics and articular contact pressure and increases the implantation failure risk. The outcomes indicate that a medial or anterior positioning of the meniscus prosthesis may be more forgiving than a posteriorly or laterally positioned prosthesis. The outcome of this study may provide a better insight into the possible consequences of meniscus prosthesis positioning errors for the patient and the prosthesis functionality.Graphical abstract

Rehabilitation of Individuals with Limb Loss due to Trauma

To provide a comprehensive overview of care and rehabilitation of those with traumatic limb loss, from preoperative to lifelong care. Comprehensive care including peer support and monitoring for the development of secondary conditions which compound disability is essential after traumatic amputation. Conditions that commonly develop after traumatic limb loss include heterotopic ossification, intact limb knee osteoarthritis, low back pain, and reduction in cardiopulmonary reserve. Optimal care for people after traumatic limb loss requires a multidisciplinary team to provide perioperative and lifelong care. In addition to ensuring optimal rehabilitation based on the individual’s vocational and avocational goals, current function, concomitant injuries, and amputation level, their psychological recovery must not be overlooked. To optimize quality of life and independence, lifelong follow-up with a physiatrist is essential to care for complications and secondary conditions, as well as to promote an active lifestyle.

In Vitro Kinematic Analysis of Single Axis Radius Posterior-Substituting Total Knee Arthroplasty.

This is an experimental study. As current posterior-substituting (PS) total knee arthroplasties have been reported to incompletely restore intrinsic joint biomechanics of the healthy knee, the recently designed single axis radius PS knee system was introduced to increase posterior femoral translation and promote ligament isometry. As there is a paucity of data available regarding its ability to replicate healthy knee biomechanics, this study aimed to assess joint and articular contact kinematics as well as ligament isometry of the contemporary single axis radius PS knee system. Implant kinematics were measured from 11 cadaveric knees using an in vitro robotic testing system. In addition, medial collateral ligament (MCL) and lateral collateral ligament (LCL) forces were quantified under simulated functional loads during knee flexion for the contemporary PS knee system. Posterior femoral translation between the intact knee and the single axis radius PS knee system differed significantly (p < 0.05) at 60, 90, and 120 degrees of flexion. The LCL force at 60 degrees (9.06 ± 2.81 N) was significantly lower (p < 0.05) than those at 30, 90, and 120 degrees of flexion, while MCL forces did not differ significantly throughout the range of tested flexion angles. The results from this study suggest that although the contemporary single axis radius PS knee system has the potential to mimic the intact knee kinematics under muscle loading during flexion extension due to its design features, single axis radius PS knee system did not fully replicate posterior femoral translation and ligament isometry of the healthy knee during knee flexion.

Hinged total knee arthroplasty for fracture cases: Retrospective study of 52 patients with a mean follow-up of 5 years

IntroductionHinged total knee arthroplasty (hTKA) is one of the treatment options available for complex fractures around an intact knee or an existing implant. The primary objective of this multicenter study was to evaluate the medium-term outcomes of hTKA for fractures. The secondary objective was to analyze the complications and risk factors based on fracture type, predisposition and time to surgery. We hypothesized that outcomes would be satisfactory, despite the context, and comparable to published data although impacted by significant mortality and morbidity. Materials and methodsWithin the framework of a symposium organized by the French Society of Orthopedic and Traumatology Surgery (SOFCOT), 52 patients from 11 hospitals were included retrospectively. All had undergone hTKA following a fracture event: recent fracture, postoperative course after a complex epiphyseal fracture on an intact knee, or periprosthetic fracture. Clinical outcomes (demographics, IKS score, Parker score, Devane score, time to surgery) and radiographic outcomes, along with complications were analyzed. ResultsOf the 52 patients included, 3 were lost to follow-up and 1 died early on. Thus, 48 patients with a mean age of 72 years (range, 31–95) were available for analysis at a mean follow-up of 59 months (range, 3–162). Forty of these patients (78%) had suffered a fracture to an intact knee and 12 (22%) had suffered a periprosthetic fracture. Of the 52 initial patients, 21 (40%) had early complications with 7 patients (19%) requiring surgical revision (5 surgical site infections, 1 extensor mechanism tear, 1 patellar dislocation). Sixteen patients (31%) developed late complications an average of 57 months after the hTKA implantation. All required surgical revision. There were 8 implant infections (15%), 3 cases of stiffness (6%), 2 extensor mechanism tears (4%) and 3 cases of loosening (6%). At a mean follow-up of 59 months, there was a 24-point improvement on the IKS pain scale (p=0.032). The postoperative activity level was unchanged in the patients who did not suffer a complication. The mortality rate was high (7/48; 15%). ConclusionOur hypothesis was confirmed since the outcomes were satisfactory, but mortality and morbidity were high. Performing hTKA remains an option in the post-fracture context, although surgeons must carefully consider the indications. Level of evidenceIV, retrospective study.

Anterolateral Ligament Reconstruction and Modified Lemaire Lateral Extra-Articular Tenodesis Similarly Improve Knee Stability After Anterior Cruciate Ligament Reconstruction: A Biomechanical Study

To determine the stabilizing role of anterolateral ligament reconstruction (ALLR) and modified Lemaire lateral extra-articular tenodesis (LET) performed in combination with anterior cruciate ligament reconstruction (ACLR) and to determine whether either procedure was superior to the other. Six nonpaired, human, fresh-frozen cadaveric knees were tested with a 6-df robotic system. Internal rotation and anterior translation of the knee were recorded from 0° to 90° of flexion after application of a 5-Nm internal rotation torque and a 134-N anterior load, respectively. A full kinematic assessment was performed in each of the following conditions: (1) intact knee, (2) after sectioning of the anterior cruciate ligament (ACL), (3) after sectioning of the ACL and anterolateral ligament, (4) after isolated ACLR, and (5) after combined ACLR and Lemaire LET and combined ACLR and ALLR. ALLR was performed using the gracilis tendon, whereas the modified Lemaire procedure was performed using the central strip of the iliotibial band. The different states were compared using a Tukey paired comparison test. In knees with combined deficiency of the ACL and anterolateral structures, anterior translation and internal rotation remained significantly increased after isolated ACLR compared with the intact knee (+2.33 ± 1.44 mm and+1.98° ± 1.06°, respectively; P < .01). On the other hand, the addition of ALLR or modified Lemaire LET to ACLR restored anterior translation and internal rotation to values similar to those in the intact knee. The 2 anterolateral procedures did not show statistically significantly different values for both tests. This difference was 0.67 ± 1.46 mm for anterior translation (P= .79) and 0.11° ± 1.11° for internal rotation (P=.99). In knees with ACL and anterolateral deficiency, combined ACLR and anterolateral reconstruction restored the native knee stability in anterior translation and internal rotation contrary to isolated ACLR. In addition, both types of extra-articular reconstruction-ALLR and modified Lemaire LET-were similar in terms of restoring knee kinematics, and neither overconstrained the knee. In knees with deficiency of the ACL and anterolateral structures, combined ACLR and anterolateral reconstruction increased knee stability at time zero after surgery. This biomechanical improvement could be responsible for the protective effect on ACL graft and meniscal repair reported in the literature after the combined procedure.

User‐feedback based robust and simplified damping control for affordable transfemoral prosthesis

The high cost of the powered prosthetic leg is one of the challenges for the lower-limb amputees in developing countries. This Letter presents a robust design and simplified control strategy for a cost-effective magnetorheological-damper-based prosthetic leg for transfemoral amputees. Herein, a simple sensing technique having an accelerometer and two force-sensing resistors is incorporated to obtain the gait events. Based on gait phase detection, a simplified if-else rule-based control strategy is implemented. A comparison between angles of prosthetic and intact knee is presented to demonstrate the effectiveness of the proposed design.

3D Imaging of Cleared Tissues

Tissue clearing technique enables visualization of opaque organ and tissue in 3‐dimension by turning tissue transparent. Current tissue clearing methods are restricted by limited types of tissue that can be cleared with each individual protocol, which inevitably led to the presence of blind‐spots within whole body or body parts imaging. Hard tissues including bones and teeth are still the most difficult organs to be cleared. In addition, endogenous fluorescence loss remains to be a major concern for solvent based clearing methods. Here, we developed a polyethylene glycol (PEG) Associated Solvent System (PEGASOS), which rendered nearly all types of tissue transparent and preserved endogenous fluorescence. Bones and teeth could be turned to nearly invisible after clearing. The PEGASOS method turned the whole adult mouse body transparent and we were able to image an adult mouse head composed of bones, teeth, brain, muscles and other tissues with no blind areas. Hard tissue transparency enabled us to reconstruct intact mandible, teeth, femur or knee joint in 3‐D. We were able to image intact mouse brain at sub‐cellular resolution and to trace individual neurons and axons over a long distance. We were able to visualize dorsal root ganglions directly through vertebrae. Finally, we revealed the neural network distribution pattern in 3‐dimension within the long bone marrow space. These results suggest that the PEGASOS method is a useful tool for general biomedical research.Support or Funding InformationThis work was supported by startup funding from Texas A&amp;M University, NIH/NIDCR grant K08DE025090, NIH/NIDCR grant R21 DE027928 and NIH/NIDCR grant R01 DE 028291 to Hu Zhao.Thy1‐EGFP spinal cord imaged with a tiling light sheet microscopeFigure 1

Tougu Xiaotong capsule exerts a therapeutic effect by improving knee meniscus in the early osteoarthritis rat model.

The aim of the study was to observe the effects of Tougu Xiaotong capsule (TGXTC) on the microstructure and ultrastructure of meniscus in rats with early knee osteoarthritis (KOA). A total of 27 Sprague Dawley rats were randomly divided into three groups: The normal group (non-papain-induced KOA; received saline only), the model group (papain-induced KOA; received saline only) and the TGXTC group [papain-induced KOA; received TGXTC (0.31g·kg-1·d-1)]. After 4 weeks treatment, the animals were anesthetized and the sagittal plane of the intact knees (n=6 per group) was obtained and prepared in paraffin section. Following hematoxylin and eosin staining, the degeneration of cartilage structure was evaluated via Mankin score, the microstructure of meniscus was observed and the area of calcification in meniscus was analyzed. Following toluidine blue staining, the content of proteoglycan in meniscus was analyzed. Three samples in each group were obtained and the ultrathin sections of meniscus were observed through a transmission electron microscope. The results showed that compared with the normal group, in the model group the joint space became narrow and the cartilage layer was slightly damaged and the Mankin score was 4.17±0.76, suggesting that the early KOA model was successfully established. After TGXTC treatment, the joint space stenosis and cartilage damage were improved as the Mankin score significantly decreased. Compared with the normal group, in the model group the surface of meniscal cartilage was much more uneven, the area of calcification was significantly increased and the content of proteoglycan of cartilage matrix was significantly decreased. However, following TGXTC treatment, the surface of the meniscal cartilage was much more smooth and flat, and the damage of tissue structure and the calcified area were significantly reduced, and the proteoglycan of cartilage matrix content was significantly increased. Compared with the normal group, the number of cellular processes and organelles, including the rough endoplasmic reticulum, mitochondria and Golgi apparatus of meniscal cartilage were reduced and swollen in the model group. In addition, the nuclei were deformed and heterochromatin agglutinated. The extracellular collagen fibrils became slender, disordered and sparse. Compared with the model group, the TGXTC group had more cell processes and organelles, alleviated swelling and heterochromatin agglutinating. Additionally, the collagen fibrils around the cells were thicker, larger and arranged in an orderly manner. In conclusion, TGXTC exerted its therapeutic effects on the development of KOA via reducing the destruction of the cartilage structure of the meniscus and improving the composition and function of the meniscus cartilage matrix.

Different effects of the lateral meniscus complete radial tear on the load distribution and transmission functions depending on the tear site.

To compare the effect of the lateral meniscus (LM) complete radial tear at different tear sites on the load distribution and transmission functions. A compressive load of 300N was applied to the intact porcine knees (n = 30) at 15°, 30°, 60°, 90°, and 120° of flexion. The LM complete radial tears were created at the middle portion (group M), the posterior portion (group P), or the posterior root (group R) (n = 10, each group), and the same loading procedure was followed. Finally, the recorded three-dimensional paths were reproduced on the LM-removed knees. The peak contact pressure (contact area) in the lateral compartment and the calculated in situ force of the LM under the principle of superposition were compared among the four groups (intact, group M, group P, and group R). At all the flexion angles, the peak contact pressure (contact area) was significantly higher (lower) after creating the LM complete radial tear as compared to that in the intact state (p < 0.01). At 120° of flexion, group R represented the highest peak contact pressure (lowest contact area), followed by group P and group M (p < 0.05). The results of the in situ force carried by the LM were similar to those of the tibiofemoral contact mechanics. The detrimental effect of the LM complete radial tear on the load distribution and transmission functions was greatest in the posterior root tear, followed by the posterior portion tear and the middle portion tear in the deep-flexed position. Complete radial tars of the meniscus, especially at the posterior root, should be repaired to restore the biomechanical function.

Reconstruction of the anterior cruciate- and anterolateral ligament deficient knee with a modified iliotibial graft reduces instability more than with an intra-articular hamstring graft.

To compare knee kinematics before and after anterior cruciate ligament ACL reconstruction (ACL-R) using hamstring graft (HG) and a double-stranded iliotibial tract graft attached to Gerdy's tubercle (providing an extra-articular anterolateral tenodesis) (named the modified iliotibial tract graft = MIT). Eighteen cadaveric knees were tested in a 6 degree of freedom kinematics rig. An optical tracking system recorded kinematics of the knee from 0 to 80 degrees of flexion applying no load, internal/external rotation (IR/ER), valgus/varus rotation (VGR/VRR), simulated pivot shift (SPS), anterior translation (AT) and posterior translation loads. The knee was tested before and after resection of the ACL and the anterolateral ligament (ALL), respectively; then after HG-ACL-R and MIT-ACL-R. Grafts were fixed at 20° of flexion. Results were compared to the intact knee. ACL resection resulted in a significant increase in AT (p < 0.05) over the entire range of motion, peaking at 20° of flexion, mean difference 6.6 ± 2.25mm (p = 0.0007). ACL-R with HG-ACL and MIT-ACL restored AT. Resection of the ALL increased IR in the fully extended knee, mean difference 2.4 ± 2.1° (p = 0.024). When compared to the intact knee and the knee after HG-ACL-R, MIT-ACL-R knee reduced IR/SPS significantly (p < 0.05) in deep flexion angles (60°-80°), peaking at 80° of flexion. The MIT-ACL-R caused significantly less VRR at 80° flexion (p = 0.02). MIT-ACL-R restored AT equally to the HG-ACL-R. The MIT-ACL-R reduced IR and SPS in deep flexion, resulting in overconstraint. MIT-ACL-R can be used as an alternative to standard reconstruction methods.

The Influence of a Single Intra-Articular Lidocaine Injection on the Viability of Articular Cartilage in the Knee.

To evaluate the in vivo effect of a single intra-articular injection of local anesthetic (LA) lidocaine on the viability of articular cartilage in the intact or osteoarthritic (OA) human knees, and to measure the synovial postinjection concentration of lidocaine in the knee. This study includes 3 interconnected experiments: (A) Synovial LA concentration measurement after a 2% lidocaine injection before knee arthroscopy in 10 patients by liquid chromatography-tandem mass spectrometry (LC-MS/MS). (B) Human osteochondral explants (N = 27) from intact knees procured at autopsies were incubated for different time intervals (30 minutes, 2 hours, 24 hours) with 2% lidocaine, 0.04% lidocaine (measured), or culture medium (control), and later evaluated for cell viability by LIVE/DEAD staining. (C) Ten out of 19 matched patients scheduled for knee replacement received a single intra-articular injection of 2% lidocaine approximately 30 minutes prior to the procedure; 9 patients served as control. Osteochondral samples with OA changes were harvested during surgery and analyzed for chondrocyte viability by LIVE/DEAD staining. (A) The synovial LA concentration was significantly lower than the primary concentration injected: average 0.23 mg/mL (0.02%), highest measured 0.37 mg/mL (0.04%). (B) In vitro exposure to a reduced LA concentration had no significant influence on chondrocyte viability in intact cartilage explants (24-hour averages: control, 93%; 0.04% lidocaine, 92%; 2% lidocaine, 79%). (C) Viability of chondrocytes in OA knees was similar between 2% lidocaine injection (85%) and control (80%). A single intra-articular knee injection of 2% lidocaine did not influence the chondrocyte viability neither in healthy nor in OA cartilage. A fast postinjection reduction of synovial LA concentration (more than 40 times) is the most likely protective mechanism.

A novel approach for optimal graft positioning and tensioning in anterior cruciate ligament reconstructive surgery based on the finite element modeling technique

BackgroundIn ACL-reconstructed patients the postoperative knee biomechanics may differ from the intact knee biomechanical behavior which can alter knee kinematics and kinetics, and as a result lead to the progression of knee osteoarthritis. The aim of this study was to demonstrate the potential of finite element models to define the optimal choices in surgical parameters in terms of optimal graft positioning in combination with graft type in order to restore the kinematic and kinetic behavior of the knee as best as possible. MethodsA workflow was proposed based on cadaveric experiments in order to restore the injured knee to a near normal physiological condition. Femoral and tibial graft insertion sites and graft fixation tension were optimized to obtain similar intact knee laxity, for three common single-bundle and one double-bundle reconstructions. To verify the success of the surgery with the variables calculated using the proposed workflow, a full walking cycle was simulated with the intact, ACL-ruptured, optimal ACL-reconstructed and non-optimal reconstructed knees. ResultsOur results suggested that for patellar tendon and hamstring tendon grafts, anatomical positioning (fixation force: 40 N), and for quadriceps tendon graft, isometric positioning (fixation tension: 85 N) could recover the intact joint kinematics and kinetics. Also for double-bundle reconstruction, with the numerically calculated optimal insertion sites, both bundles needed 50-N fixation force. ConclusionsWith optimal graft positioning parameters, following the proposed workflow in this study, any of the single-bundle graft types and surgical techniques (single vs. double-bundle) may be used to acceptably recover the intact knee joint biomechanical behavior.

Biomechanical evaluation of PCL reconstruction with suture augmentation

PurposeThe purpose of this study was to compare kinematics and patellofemoral contact pressures of all inside and transtibial single bundle PCL reconstructions and determine if suture augmentation further improves the biomechanics of either technique. MethodsCadaveric knees were tested with a posterior drawer force, and varus, valgus, internal and external moments at 30, 60, 90, and 120° of flexion. Displacement, rotation, and patellofemoral contact pressures were compared between: Intact, PCL-deficient, All-Inside PCL reconstruction with (AI-SA) and without (AI) suture augmentation, and transtibial PCL reconstruction with (TT-SA) and without (TT) suture augmentation. ResultsSectioning the PCL increased posterior tibial translation (PTT) from intact at 60° to 120° of flexion, p < 0.001. AI PCL reconstruction improved stability from the deficient-state but had greater PTT than intact at 90° of flexion, p < 0.05. Adding suture augmentation to the AI reconstruction further reduced PTT to levels that were not statistically different from intact at all flexion angles. TT reconstructed knees had greater PTT than intact knees at 60, 90, and 120° of flexion, p < 0.01. Adding suture augmentation (TT-SA) improved posterior stability to PTT levels that were not statistically different from intact knees at 30, 60, and 120° of flexion. Patellofemoral pressures were highest in PCL-deficient knees at increased angles of flexion and were reduced after reconstruction, but this was not significant. ConclusionIn this time-zero study, both the all-inside and transtibial single bundle PCL reconstructions effectively reduce posterior translation from the deficient-PCL state. In addition, suture augmentation of both techniques provided further anterior–posterior stability.

A biomechanical study after combined reconstruction of the anterior cruciate and anterolateral ligaments: Comparison between anatomic anterolateral ligament reconstruction and lateral tenodesis using the modified Lemaire technique

Objectives:To determine the stabilizing role of the anterolateral ligament reconstruction (ALLR) and the modified Lemaire lateral extraarticular tenodesis (LET) performed in combination with anterior cruciate ligament reconstruction (ACLR) and to determine if one of these two procedures was superior to the other.Methods:Six non paired cadaveric knees were tested with a 6 degrees of freedom robotic system (KUKA Robotics). Internal rotation and anterior tibial translation were measured between 0 and 90° knee flexion after applying 5 N-m Torque and a 134-N anterior load, respectively. A full kinematics assessment was performed in each following conditions: intact knee, after section of the anterior cruciate ligament (ACL), after section of the ACL and anterolateral ligament (ALL) and Kaplan fibers, after isolated ACLR, after combined ACLR+LET and ACLR+ALLR. ALLR was performed using Gracilis tendon while central strip of the ilio-tibial band was used for the modified Lemaire procedure.These different states were compared using a Tukey paired comparison test.Results:In combined ACL and anterolateral deficient knee, anterior translation and internal rotation remained significantly increased after isolated ACLR compared to intact knee (+2.33 ± 1.44 mm and +1.98 ± 1.06°; p > 0.01). On the other hand, the addition of an ALLR or a modified Lemaire LET to the ACLR allowed to restore anterior translation and internal rotation to values similar to the intact knee. Finally, the two anterolateral procedures had not significantly different values in both tests. This difference was 0.67 ± 1.46 mm for anterior translation (p=0.79) and 0.11 ± 1.11° for internal rotation (p=0.99).Conclusion:In ACL and anterolateral deficient knee, combined ACLR and anterolateral reconstruction allowed restoration of native stability of the knee in anterior translation and internal rotation contrary to isolated ACLR.Additionally, both types of extra-articular reconstruction, ALLR or modified Lemaire procedure, were similar in terms of restoring knee kinematics and neither overconstrained the knee.

A biomechanical comparison of the main anterolateral procedures used in combination with anterior cruciate ligament reconstruction

Background:None of the anterolateral procedures used in combination with ACL reconstruction (ACLR) to control rotational laxity have demonstrated superiority. The objective was to compare the capacity of the main anterolateral procedures associated with ACLR to restore intact knee kinematics in case of combined ACL and anterolateral structure injury.Methods:The complete kinematics of 10 cadaveric knees, previously modelled by TDM, were recorded using a 3D Motion Analysis® system. Intact knee kinematics, including internal rotation (IR) of the tibial and anterior-posterior (AP) laxity at 30 and 90° flexion were initially assessed, followed by a sequential section of the ACL and anterolateral complex (ALC) (anterolateral ligament (ALL), ALL capsule and Kaplan fibers). After the ACLR, 5 anterolateral procedures were performed consecutively on the same knee: ALLR; Ellison; Deep Lemaire; Superficial Lemaire; and MacIntosh. The last three procedures were randomized. For each procedure, the graft was fixed in neutral rotation at 30° flexion with a tension of 20 N.Results:ACLR alone did not restore overall knee kinematics when there was an ACL+ALC injury, and resulted in residual rotational laxity of the tibia (p > 0.001). Only the ALLR (p=0.262) and modified Ellison (p=0.081) procedures restored normal global IR kinematics. Superficial/deep Lemaire and MacIntosh procedures resulted in over-constrained kinematic profiles (respectively: p=0.013, p=0.018 and p=0.030). In terms of ACLR, the addition of an anterolateral procedure did not provide additional control over AP translation at 30 and 90° (p > 0.05), exception for the surficial Lemaire procedure at 90° (p = 0.032).Discussion:ACLR alone was not sufficient to restore normal kinematics in ACL and ALC-deficient knees. ALLR and Ellison procedures restored physiological kinematics, unlike the MacIntosh procedure which caused additional control of IR and thereby induced over-constraint.Conclusion:The addition of ALLR or the modified Ellison procedure, which restore intrinsic kinematics, might be useful during primary ACL reconstruction to avoid repeated injury without a risk of over-constraint. The superficial/deep Lemaire and MacIntosh procedures resulted in over-constrained kinetics but provided additional rotation control that could be useful in revision surgery.