Relationship Between Intraoperative Macroscopic Anterior Cruciate Ligament Findings, Perioperative Surgical Findings, and Postoperative Clinical Outcome After Cruciate-Retaining Total Knee Arthroplasty.

PURPOSE: To assess how intraoperative macroscopical anterior cruciate ligament (ACL) findings affect perioperative procedures, biomarkers, and postoperative anterior-posterior (AP) laxity and range of motion (ROM) after cruciate-retaining (CR) total knee arthroplasty (TKA) and to determine how chronic ACL deficiency may affect postoperative inflammatory biomarker, AP laxity, and ROM. METHODS: A total of 121 patients with varus knee osteoarthritis without a history of ACL injury who underwent ATTUNE® (DePuy Synthes, Warsaw, IN) CR TKA were analyzed. Intraoperative ACL findings were stratified into intact, damaged, and diminished, according to the tension by probing, synovial coverage, and vascularity. C-reactive protein (CRP) levels were examined at one, seven, and 14 days after surgery. Knee AP laxity measurements using Kneelax 3 (Monitored Rehab Systems, Haarlem, The Netherlands) and postoperative knee ROM were also compared. RESULTS: One-way ANOVA showed significant differences in CRP levels examined one day after surgery observed between the three groups (8.4 (3.8), 9.8 (4.3), and 13.2 (7.7) mg/dL, respectively; P = 0.018), with post hoc analysis showing that CRP levels one day after surgery were significantly greater in the diminished group than in the intact and damaged groups (P = 0.012 and 0.023, respectively). AP laxity in 30° of knee flexion was observed between the three groups (5.4 (2.3), 5.8 (2.5), and 7.1 (2.8) mm, respectively; P = 0.039), with post hoc analysis showing that AP laxity in 30° of knee flexion was significantly greater in the diminished group than in the intact group (P = 0.038). Knee ROM showed no significant differences. CONCLUSION: Intraoperative ACL diminishment was associated with higher CRP one day after surgery and midrange AP laxity one year after surgery.

Can tibia-first total knee arthroplasty using computer-assisted system improve anterior and posterior knee stability?

BACKGROUND: Total knee arthroplasty (TKA) is a widely performed procedure to alleviate pain and restore function of patients with end-stage knee osteoarthritis. OBJECTIVE: The study aim was to determine if tibia-first (TF) total knee arthroplasty (TKA) using a novel computer-assisted surgery (CAS) system can yield better anterior and posterior (AP) knee stability. METHODS: Patients with knee osteoarthritis with obvious varus knee who met the indication for and underwent TKA from May 2019 to November 2020 were included. Forty-one measured resection (MR)-TKAs and 32 TF-TKAs were compared. The varus-valgus ligament balance and joint tension at a joint center-gap setting equal to the tibial-baseplate thickness were measured, and appropriate polyethylene inserts with 0∘, 30∘, 45∘, 60∘, 90∘, and 120∘ of knee flexion were placed. A Kneelax 3 arthrometer was used to measure knee AP laxity in the postoperative anesthetized patients with 30∘ and 90∘ of knee flexion. RESULTS: The horizontal gap balance was significantly closer in the TF-TKA group than the MR-TKA group for 0∘, 30∘, 45∘, and 60∘ of knee flexion. In contrast, no significant differences were observed for 90∘ and 120∘ of knee flexion. No significant differences in joint-gap tensions among all knee-flexion angles were observed. Translation was significantly smaller in the TF-TKA group than the MR-TKA group for AP laxity with 30∘ of knee flexion (8.8 ± 2.9 mm vs. 10.7 ± 3.1 mm, P= 0.0079). In contrast, no significant AP laxity was observed with 90∘ of knee flexion (7.2 ± 2.8 mm vs. 7.2 ± 3.5 mm). CONCLUSION: TF-TKA using a novel CAS system provided better AP knee stability with close to horizontal gap balances.

Biomechanical Comparisons of Anterior Cruciate Ligament Avulsion Fracture Fixation Using High-Strength Suture and Ultra-High Molecular Weight Polyethylene Suture Tape in a Porcine Model.

A wide variety of fixation methods have been reported to fix anterior cruciate ligament (ACL) tibial avulsion fractures, but there have been no studies into the fixation of these fractures with ultra-high molecular weight polyethylene (UHMWPE) suture tape as an alternative to conventional thread. Type III ACL tibial avulsion fractures were created in 20 skeletally immature porcine knees. All specimens were randomized into two treatment groups: (1) pullout repair using no. 2 suture fixation and (2) pullout repair using UHMWPE suture tape fixation. The specimens were tested cyclically (20 cycles, 0-40 N, 100 mm/min) in the direction of the native ACL and loaded to failure (100 mm/min) on a tensile tester. Statistically significant differences between the structural properties (displacement, upper yield load, maximum load, linear stiffness, and elongation at failure) under cyclic loading and single-cycle loading were analyzed. Displacement during cyclic testing was 1.56 ± 1.03 mm in the UltraBraid group and 0.99 ± 0.48 mm in the SUTURETAPE group, with no significant differences found between the groups (p = 0.13). There were no significant differences in upper yield load (161.9 ± 68.9 N in the UltraBraid group, 210.4 ± 60.1 N in the SUTURETAPE group, p = 0.11), linear stiffness (14.7 ± 4.7N/mm in the UltraBraid group, 18.1 ± 7.9 N/mm in the SUTURETAPE group, p = 0.27), or elongation at failure (20.1 ± 8.0 mm in the UltraBraid group, 21.5 ± 7.2 mm in the SUTURETAPE group, p = 0.69). On the other hand, significant differences were observed in maximum load in the SUTURETAPE group (219.7 ± 89.2 N in the UltraBraid group, 319.3 ± 92.6 N in the SUTURETAPE group, p = 0.025).

Evaluation of Tibial Tunnel Location with the Femoral Tunnel Created Behind the Resident's Ridge in Transtibial Anterior Cruciate Ligament Reconstruction.

Few studies have determined whether a femoral bone tunnel could be created behind the resident's ridge by using a transtibial (TT) technique-single bundle (SB)-anterior cruciate ligament (ACL) reconstruction. The aim of this study was to clarify (1) whether it is possible to create a femoral bone tunnel behind the resident's ridge by using the TT technique with SB ACL reconstruction, (2) to define the mean tibial and femoral tunnel angles during anatomic SB ACL reconstruction, and (3) to clarify the tibial tunnel inlet location when the femoral tunnel is created behind resident's ridge. Arthroscopic TT-SB ACL reconstruction was performed on 36 patients with ACL injuries. The point where 2.4-mm guide pin was inserted was confirmed, via anteromedial portal, to consider a location behind the resident's ridge. Then, an 8-mm diameter femoral tunnel with a 4.5-mm socket was created. Tunnel positions were evaluated by using three-dimensional computed tomography (3D-CT) 1 week postoperatively. Quadrant method and the resident's ridge on 3D-CT were evaluated to determine whether femoral tunnel position was anatomical. Radiological evaluations of tunnel positions yielded mean ( ± standard deviation) X- and Y-axis values for the tunnel centers: femoral tunnel, 25.2% ± 5.1% and 41.6% ± 10.2%; tibial tunnel, 49.2% ± 3.5%, and 31.5% ± 7.7%. The bone tunnels were anatomically positioned in all cases. The femoral tunnel angle relative to femoral axis was 29.4 ± 5.5 degrees in the coronal view and 43.5 ± 8.0 degrees in the sagittal view. The tibial tunnel angle relative to tibial axis was 25.5 ± 5.3 degrees in the coronal view and 52.3 ± 4.6 degrees in the sagittal view. The created tibial bone tunnel inlet had an average distance of 13.4 ± 2.7 mm from the medial tibial joint line and 9.7 ± 1.7 mm medial from the axis of the tibia. Femoral bone tunnel could be created behind the resident's ridge with TT-SB ACL reconstruction. The tibial bone tunnel inlet averaged 13.4 mm from the medial tibial joint line and 9.7 mm medial from the tibia axis.

Histological Evaluation of Harvested Specimen of a Patient Who Underwent Unicompartmental Knee Arthroplasty Two Years and Six Months After Medial Meniscus Posterior Root Tear Transtibial Pull-Out Repair.

Transtibial pull-out repair is routinely performed to treat medial meniscal posterior root tear (MMPRT). However, data on the postoperative histological evaluation of the repaired medial meniscus posterior attachment after the procedure is scarce. In this report, we present a histological evaluation of the harvested specimen of a patient who underwent unicompartmental knee arthroplasty (UKA) approximately two years and six months after MMPRT transtibial pull-out repair. The patient was a 75-year-old female. Her X-ray showed Kellgren-Lawrence classification grade II and her MRI revealed MMPRT. Arthroscopic transtibial pull-out repair was performed two months after the onset, and her condition was fine two years after the operation. However, her knee pain gradually worsened, and UKA was performed two years and six months after the initial surgery. The medial meniscus posterior root was continuous from the resected tibia. Tissue specimens were prepared and evaluated. There were Sharpey's fiber-like tissues in the tibial bone tunnel. The medial meniscus posterior attachment showed a four-layer structure of ligaments, uncalcified fibrocartilage, calcified fibrocartilage, and subchondral bone zone. The structures were observed 2,000 ㎛ medially from the bone tunnel. The results revealed that the reconstructed graft after a transtibial pull-out repair for the medial meniscus posterior root showed different histological findings compared with the native posterior root and similar to the anterior root of the medial meniscus.

Internal bracing with an artificial ligament for superficial medial collateral ligament injury impairs the mechanical property of repaired native ligament: A porcine study.

BACKGROUND: Superficial medial collateral ligament (sMCL) injury is common, but there are no in vivo studies describing the biomechanical efficacy of anatomic repair with internal bracing for grade 3 injuries. METHODS: We used a porcine model to evaluate the efficacy of internal bracing using an artificial ligament for the early repair of acute, grade 3 sMCL injuries. Sixteen male castrated pigs were randomly assigned to a repair group: (1) anatomic repair using two suture anchors (Group R; n = 9) or (2) anatomic repair with internal bracing augmentation (Group IB; n = 7). The left knees were allocated to a sham surgery group (Group S; n = 16). All animals were sacrificed 4 weeks after surgery. The right and left femur-sMCL-tibia complexes were mounted on a tensile tester and stretched to failure using the same conditions as preconditioning at a cross-head speed of 50 mm/min. The internal bracing in Group IB was removed prior to the biomechanical testing. The failure mode and structural properties (upper yield load, maximum load, linear stiffness, and elongation at failure) were determined. RESULTS: Significant differences in failure mode were observed among the three groups. All sMCLs repaired with just the suture anchors (Group R) were avulsed from the femoral attachment, while most of the sMCLs repaired with internal bracing augmentation (Group IB) exhibited mid-substance tears (Group R vs Group IB, P = 0.0023). In Group S, 14 sMCLs were avulsed from the femoral attachment and two were avulsed from the tibial attachment (Group IB vs Group S, P < 0.001). No significant difference was observed between Group R and Group S. There were no significant differences in the upper yield load, maximum load, linear stiffness, or elongation at failure among the groups. CONCLUSIONS: Loading of an artificial ligament for internal bracing did not result in better structural properties of the repaired sMCL itself.

Willingness of Patients With Knee Osteoarthritis to Use Telemedicine Amid Sars-CoV-2 Outbreak.

BACKGROUND: There is no report yet on the application of telemedicine in orthopedic practice in Japan. With a focus on patients with KOA, we investigated the willingness of patients to use telemedicine by assessing factors such as the patient's age, smartphone possession, hospital visiting time, and severity of KOA. METHODS: Data of patients who regularly consulted orthopedic surgeons at our institutions from April 2020 to June 2020 were retrospectively analyzed using an electronic medical database. The patients were diagnosed with KOA according to clinical and radiological findings, according to the Kellgren-Lawrence (KL) classification. included were patients with KOA with KL classification above grade 2. All patients were asked: 1) whether they were willing to use telemedicine (Yes or No), 2) the reason why they answered Yes, 3) the reason why they answered No, 4) if they possessed a smartphone, 5) their numeric rating scale for pain at their last outpatient visit after the Sars-CoV-2 epidemic emerged, and 6) the time required for visiting hospital from their house. Patients were stratified into 2 groups depending on whether they answered Yes (Group Y) or No (group N). Comparisons between the groups concerning smartphone possession, NRS pain, hospital visiting times, and distribution of KL grade were made. RESULTS: Only 36.7% of the patients with KOA said they were willing to use telemedicine. The average age of group Y was significantly younger than that of group N (67.9 ± 9.1 vs 73.1 ± 8.0, P = 0.0026) and the cutoff age was 70.0 years. In addition, the rate of smartphone possession was significantly higher in group Y than in group N (82.5% vs 34.5%, P < 0.001). Hospital visit times and the severity of KOA did not differ between the groups. CONCLUSION: Age is a barrier to the adoption of telemedicine.

Serial passage of a street rabies virus in mouse neuroblastoma cells resulted in attenuation: potential role of the additional N-glycosylation of a viral glycoprotein in the reduced pathogenicity of street rabies virus.

Street rabies viruses are field isolates known to be highly neurotropic. However, the viral elements related to their pathogenicity have yet to be identified at the nucleotide or amino acid level. Here, through 30 passages in mouse neuroblastoma NA cells, we have established an attenuated variant of street rabies virus strain 1088, originating from a rabid woodchuck followed by 2 passages in the brains of suckling mice. The variant, 1088-N30, was well adapted to NA cells and highly attenuated in adult mice after intramuscular (i.m.) but not intracerebral (i.c.) inoculations. 1088-N30 had seven nucleotide substitutions, and the R196S mutation of the G protein led to an additional N-glycosylation. Street viruses usually possess one or two N-glycosylation sites on the G protein, 1088 has two, while an additional N-glycosylation site is observed in laboratory-adapted strains. We also established a cloned variant 1088-N4#14 by limiting dilution. Apart from the R196S mutation, 1088-N4#14 possessed only one amino acid substitution in the P protein, which is found in several field isolates. 1088-N4#14 also efficiently replicated in NA cells and was attenuated in adult mice after i.m. inoculations, although it was more pathogenic than 1088-N30. The spread of 1088-N30 in the brain was highly restricted after i.m. inoculations, although the pattern of 1088-N4#14's spread was intermediate between that of the parental 1088 and 1088-N30. Meanwhile, both variants strongly induced humoral immune responses in mice compared to 1088. Our results indicate that the additional N-glycosylation is likely related to the reduced pathogenicity. Taken together, we propose that the number of N-glycosylation sites in the G protein is one of the determinants of the pathogenicity of street rabies viruses.