Safe Ultrasonography-Assisted Knee Posterior Transseptal Portal Creation Technique.

Knee arthroscopy is a minimally invasive surgical technique that allows surgeons to diagnose and treat various knee conditions using much smaller incisions than open surgery. However, it is difficult to fully visualize the posterior compartment of the knee joint using the usual anterior portal approach because of blind spots. The transseptal portal technique enables surgeons to visualize the surgical field and access instruments in the posterior compartment of the knee during arthroscopic surgery. However, creation of the posterior transseptal portal increases the risk of neurovascular injury. Particular attention should be paid to avoid damaging the saphenous nerve, common peroneal nerve, popliteal artery, and tibial nerve. Here, we describe an ultrasonography-guided surgical method for creating the posterior transseptal portal by confirming the surrounding anatomy.

Targeting of Periprosthetic Muscles for the Ultrasonographic Screening of Hip Abnormalities in Hip Resurfacing Arthroplasty Patients.

BACKGROUND: Hip resurfacing arthroplasty (HRA) patients require subsequent annual screening for postoperative complications. Ultrasonography may be useful for this purpose but lacks a screening protocol for hips. The purpose of this study was to evaluate the accuracy of ultrasonography for detecting postoperative complications in HRA patients using a screening protocol that specifically targets periprosthetic muscles. METHODS: We enrolled 45 hips from 40 HRA patients with a mean follow-up period of 8.2 years. MRI and ultrasonography scans were simultaneously conducted at follow-up. The ultrasonography assessments were conducted on the anterior part of the hip that targets iliopsoas, sartorius, rectus femoris, lateral with anterior superior and inferior iliac spine (ASIS and AIIS) as bony landmarks, and the lateral and posterior parts that target fascia tensor, short rotators, and gluteus minimus, medius, and maximus with greater trochanter and ischial tuberosity as bony landmarks. The accuracy of diagnosing postoperative abnormalities and the visibility of periprosthetic muscles were compared between these two modalities. RESULTS: Both MRI and ultrasonography detected an abnormal region in eight cases comprising two infections, two pseudotumors, and four patients with greater trochanteric bursitis. Among these cases, four hips required implant removal. The increase in anterior space, measured as the distance between the iliopsoas and resurfacing head, was a good indicator for the abnormal mass in these four HRA cases. In the assessment of periprosthetic muscles, MRI showed a much lower visibility than ultrasonography in the iliopsoas (6.7% vs. 100%), gluteus minimus (6.7% vs. 88.9%), and short rotators (8.8% vs. 71.4%) due to implant halation. CONCLUSIONS: By targeting periprosthetic muscles, ultrasonography can detect postoperative complications as effectively as MRI assessments in HRA patients. Ultrasonography has superior visibility in the periprosthetic muscles of HRA patients, indicating its utility for the screening of small legions in these cases which may not be visible by MRI.

Medial meniscus extrusion and stage are related to the size of spontaneous osteonecrosis of the knee in patients who underwent high tibial osteotomy.

PURPOSE: Spontaneous osteonecrosis of the knee (SONK) causes acute atraumatic knee pain, and meniscus tears may be associated with the pathogenesis of SONK. The purpose of this study was to investigate the relationship of the type of meniscus tear and medial meniscus extrusion with SONK on the medial femoral condyle in patients who underwent surgical treatment with high tibial osteotomy due to severe knee pain. METHODS: We enrolled 98 patients with 102 knees who underwent medial opening wedge high tibial osteotomy (OWHTO) under the diagnosis of medial femoral condyle osteonecrosis at our hospital from December 2003 to January 2020. Based on the Koshino classification, cases of SONK were classified as stage 1-4. The relationships of demographic data, X-rays and MRI images, including femorotibial angle (FTA), meniscus tear type, and medial meniscus extrusion (MME), with the stage and volume of SONK were investigated. RESULTS: Ninety-eight patients (29 males and 69 females), with an average age at surgery of 69.2 ± 9.6 years and Body mass index(BMI) of 61.0 ± 17.6 kg/m2. In 102 cases of SONK, 11 knees, 18 knees, 46 knees, and 27 knees were classified as stage 1-4, respectively. The mean SONK volume was 2161.61 µm (range 95.67-7484.68 µm) on preoperative MRI. The preoperative FTA (mean 180.86°, range 172-187°) was not associated with the stage or volume of SONK. Meniscus tears were found in all cases of SONK and consisted of 2 degenerations, 2 horizontal tears, 0 vertical tears, 40 radial tears, 4 complex tears, and 54 medial meniscus posterior root tears (MMPRTs). In addition, 99% (101/102) of knees showed more than 3 mm of meniscus extrusion. Although the meniscus tear type was not associated with SONK stage, there was a high rate of tears that caused disruption of the hoop strain, such as MMPRTs (52.9%) or radial tears (39.2%). MME was significantly related to SONK volume (r = 0.387, p < 0.001). CONCLUSION: All patients with SONK had coexisting meniscus tears, most menisci had medial extrusion, and a positive correlation was observed between MME and SONK volume.

Return to sports activity after opening wedge high tibial osteotomy in patients aged 70 years and older.

BACKGROUND: The purpose of this study was to evaluate return to sports (RTS) after opening wedge high tibial osteotomy (OWHTO) in elderly patients and associated factors affecting RTS. METHODS: Seventy-four patients (mean age 68 years) who underwent OWHTO were enrolled. Clinical outcomes were evaluated using the Knee Society Score (KSS). Patients were asked regarding types of sports activities and their levels of participation within preoperative 1 year and postoperative 1 year. Levels of participation in sports and recreational activities were examined using the Tegner activity scale. The outcomes were compared between two age groups (≥ 70 years vs. < 70 years). RESULTS: Of the 74 patients overall, 59 participated in at least one sport preoperatively, and 55 returned to sports postoperatively (RTS 93%). The KSS knee score and function score were significantly improved after surgery in both age groups (P < 0.05), but no significant differences were found between the age groups. The Tegner activity scales for ≥ 70 years and < 70 years were 2.9 ± 1.1 and 4.0 ± 1.9 preoperatively (P < 0.01) and 2.7 ± 1.2 and 3.3 ± 1.4 postoperatively (P = 0.16), respectively. RTS was reported by 24 of 25 (96.0%) in the age < 70 years group and 31 of 34 (91.2%) in the age ≥ 70 years group. Majority of age ≥ 70 years participated in low-impact sports preoperatively and returned to the same impact level postoperatively. CONCLUSIONS: The rate of RTS after OWHTO was high in patients aged 70 years and older with low-impact level. OWHTO is a preferred surgical option for elderly patients who desire RTS.

Brain-stiffness-mimicking tilapia collagen gel promotes the induction of dorsal cortical neurons from human pluripotent stem cells.

The mechanical properties of the extracellular microenvironment, including its stiffness, play a crucial role in stem cell fate determination. Although previous studies have demonstrated that the developing brain exhibits spatiotemporal diversity in stiffness, it remains unclear how stiffness regulates stem cell fate towards specific neural lineages. Here, we established a culture substrate that reproduces the stiffness of brain tissue using tilapia collagen for in vitro reconstitution assays. By adding crosslinkers, we obtained gels that are similar in stiffness to living brain tissue (150-1500 Pa). We further examined the capability of the gels serving as a substrate for stem cell culture and the effect of stiffness on neural lineage differentiation using human iPS cells. Surprisingly, exposure to gels with a stiffness of approximately 1500 Pa during the early period of neural induction promoted the production of dorsal cortical neurons. These findings suggest that brain-stiffness-mimicking gel has the potential to determine the terminal neural subtype. Taken together, the crosslinked tilapia collagen gel is expected to be useful in various reconstitution assays that can be used to explore the role of stiffness in neurogenesis and neural functions. The enhanced production of dorsal cortical neurons may also provide considerable advantages for neural regenerative applications.

Risk factors for prolonged operative time in femoral neck fracture patients undergoing hemiarthroplasty through direct anterior approach.

BACKGROUND: The use of direct anterior approach (DAA) for hemiarthroplasty in femoral neck fracture patients has recently increased worldwide. However, no previous studies have elucidated or validated risk factors for prolonged operative time in hemiarthroplasty through DAA. Accurately predicting operative time would contribute to and the selection of the most appropriate surgical approach for each patient and the effective use of operating room. METHODS: Data from 151 femoral neck fracture patients who underwent hemiarthroplasty through DAA were evaluated. A multiple linear regression model of the operative time of hemiarthroplasty was developed, including age, sex, body mass index (BMI), surgeons' DAA experience and approach depth (cm) on the axial computed tomography (CT) slice of the hip as independent factors. RESULTS: Mean age at admission was 83.8 [±6.3 standard deviation (SD)] years and mean operative time was 93.1 (±21 SD) min. Operative time increased by 20 min for every 1 cm increase in approach depth [partial regression coefficient (B), 20.4; standardized partial regression coefficient (ß), 0.68; p < 0.001] and increased 13 min when the DAA was performed by a surgeon with DAA experience of <20 cases (B, 13.1; ß, 0.29; p < 0.001). The adjusted R2 of the model was 0.57. CONCLUSIONS: We demonstrated that increased approach depth and surgeons' DAA experience (<20 cases) are novel risk factors for prolonged operative time in femoral neck fracture patients undergoing hemiarthroplasty through DAA. Surgeons should consider these factors when estimating the operative time of surgery and selecting the most appropriate and safe surgical approach for a patient undergoing hemiarthroplasty.

Increasing Elasticity through Changes in the Secondary Structure of Gelatin by Gelation in a Microsized Lipid Space.

Even though microgels are used in a wide variety of applications, determining their mechanical properties has been elusive because of the difficulties in analysis. In this study, we investigated the surface elasticity of a spherical microgel of gelatin prepared inside a lipid droplet by using micropipet aspiration. We found that gelation inside a microdroplet covered with lipid membranes increased Young's modulus E toward a plateau value E* along with a decrease in gel size. In the case of 5.0 wt % gelatin gelled inside a microsized lipid space, the E* for small microgels with R ≤ 50 µm was 10-fold higher (35-39 kPa) than that for the bulk gel (∼3 kPa). Structural analysis using circular dichroism spectroscopy and a fluorescence indicator for ordered beta sheets demonstrated that the smaller microgels contained more beta sheets in the structure than the bulk gel. Our finding indicates that the confinement size of gelling polymers becomes a factor in the variation of elasticity of protein-based microgels via secondary structure changes.

Low-intensity pulsed ultrasound accelerates fracture healing by stimulation of recruitment of both local and circulating osteogenic progenitors.

We investigated the effect of low-intensity pulsed ultrasound (LIPUS) on the homing of circulating osteogenic progenitors to the fracture site. Parabiotic animals were formed by surgically conjoining a green fluorescent protein (GFP) mouse and a syngeneic wild-type mouse. A transverse femoral fracture was made in the contralateral hind limb of the wild-type partner. The fracture site was exposed to daily LIPUS in the treatment group. Animals without LIPUS treatment served as the control group. Radiological assessment showed that the hard callus area was significantly greater in the LIPUS group than in the control group at 2 and 4 weeks post-fracture. Histomorphometric analysis at the fracture site showed a significant increase of GFP cells in the LIPUS group after 2 weeks (7.5%), compared to the control group (2.4%) (p < 0.05). The LIPUS group exhibited a significantly higher percentage of GFP cells expressing alkaline phosphatase (GFP/AP) than the control group at 2 weeks post-fracture (5.9%, 0.3%, respectively, p < 0.05). There was no significant difference in the percentage of GFP/AP cells between the LIPUS group (2.0%) and the control group (1.4%) at 4 weeks post-fracture. Stromal cell derived factor-1 and CXCR4 were immunohistochemically identified at the fracture site in the LIPUS group. These data indicate that LIPUS induced the homing of circulating osteogenic progenitors to the fracture site for possible contribution to new bone formation.