Usefulness of Probing Sensor Device for Evaluating Meniscal Suture and Scaffold Implantation.

Appropriate suture tension is a key factor in successful meniscal repair. This study aimed to clarify the appropriate value of meniscal stabilization with suture repair based on a probing procedure for healthy porcine menisci and a novel meniscal scaffold. After evaluating the reliability of the probing sensor, meniscal vertical tear and partial meniscectomy models were developed, in which suture repair and meniscal scaffold implantation were performed at suture intervals ranging between 20 and 2.5 mm. The residence forces at each interval were evaluated using a probing sensor. Moreover, a tensile test was conducted to evaluate the displacement and presence or absence of gaps. We found that normal and meniscal scaffolds should be fixed within 5 mm of suture interval. The probing residence forces required were at least 1.0 N for vertical tears and 3.0 N for meniscal scaffolds. These findings may be taken into consideration to reduce suture failure following meniscal tear repair and stabilizing meniscal scaffold fixation.

Determining the Relationship between Mechanical Properties and Quantitative Magnetic Resonance Imaging of Joint Soft Tissues Using Patient-Specific Templates.

To determine whether the mechanical properties of joint soft tissues such as cartilage can be calculated from quantitative magnetic resonance imaging (MRI) data, we investigated whether the mechanical properties of articular cartilage and meniscus scheduled to be resected during arthroplasty are correlated with the T2 relaxation time on quantitative MRI at the same location. Six patients who had undergone knee arthroplasty and seven who had undergone hip arthroplasty were examined. For the knee joint, the articular cartilage and lateral meniscus of the distal lateral condyle of the femur and proximal lateral tibia were examined, while for the hip joint, the articular cartilage above the femoral head was studied. We investigated the relationship between T2 relaxation time by quantitative MRI and stiffness using a hand-made compression tester at 235 locations. The patient-individualized template technique was used to align the two measurement sites. The results showed a negative correlation (from -0.30 to -0.35) in the less severely damaged articular cartilage and meniscus. This indicates that tissue mechanical properties can be calculated from T2 relaxation time, suggesting that quantitative MRI is useful in determining when to start loading after interventional surgery on cartilage tissue and in managing the health of elderly patients.

Horseradish Peroxidase-Mediated Bioprinting via Bioink Gelation by Alternately Extruded Support Material.

Horseradish peroxidase (HRP)-mediated extrusion bioprinting has a significant potential in tissue engineering and regenerative medicine. However, they often face challenges in terms of printing fidelity and structural integrity when using low-viscosity inks. To address this issue, a method that alternately extrudes bioinks and support material was developed in this study. The bioinks consisting of cells, HRP, and phenolated polymers, and the support material contained hydrogen peroxide (H2O2). The support material not only prevented the collapse of the constructs but also supplied H2O2 to facilitate the enzymatic reaction. 3D constructs with tall and complex shapes were successfully printed from a low-viscosity ink containing 10 U/mL HRP and 1.0% w/v phenolated hyaluronic acid (HA-Ph), with a support material containing 10 mM H2O2. Over 90% viability of mouse fibroblasts (10T1/2) was achieved following the printing process, along with a morphology and proliferation rate similar to that of nontreated cells. Furthermore, human hepatoblastoma (HepG2) cells showed an increased spheroid size over 14 days in the printed constructs. The 10T1/2 cells adhered and proliferated on the constructs printed from inks containing both phenolated gelatin and HA-Ph. These results demonstrate the great potential of this HRP-mediated extrusion bioprinting technique for tissue engineering applications.

Validation of a Method to Measure the T2 Value from the Color Mapping by Hue Value.

BACKGROUND: Color mapping using quantitative MRI (Magnetic Resonance Imaging) is now being reported in various medical fields to be useful in showing tissue conditions and morphological perspectives. Specifically, T2 mapping, as one of the color mapping has been used to describe cartilage conditions in orthopedics. However, for orthopedic physicians in outpatient clinics, the color mapping shows only the colors on the mapping to patients without explaining their numerical values. METHODS: Our study proposed an approach to measure T2 values based on the hue value converted from Red, Green, Blue information on the processed color map to address this issue. We evaluated the validity of our method with 25 subjects. RESULTS: Our proposed method showed a good and high correlation coefficient (r = 0.9924, p < 0.0001), and the difference in the T2 values using dedicated software on the console of the MRI scanner and our method was small (its absolute value was approximately 1.5, p = 0.008). CONCLUSION: Therefore, we consider the proposed method is an alternative approach to show the T2 value when the color mapping is available.

Correlation between the elastic modulus of anterior cruciate ligament (ACL) and quantitative ultrashort echo time (UTE) magnetic resonance imaging.

Conventional magnetic resonance imaging (MRI) often acquires no signal in anterior cruciate ligament (ACL) due to the short apparent transverse relaxation time of ACL. Ultrashort echo time (UTE) MRI is capable of imaging ACL with high signal which enables quantitative ACL assessment. This study aimed to investigate the correlations of the mechanical and microstructural properties of human ACL specimens with quantitative three-dimensional UTE Cones (3D-UTE-Cones) MRI measures. ACL specimens were harvested from cadaveric knee joints of 13 (50.9 ± 21.1 years old, 11 males and 2 female) donors. Specimens were scanned using a series of quantitative 3D-UTE-Cones T2 * (UTE-T2 *), T1 (UTE-T1 ), Adiabatic T1ρ (UTE-Adiab-T1ρ ), and magnetization transfer (UTE-MT) sequences in a wrist coil on a clinical 3T scanner. ACL elastic modulus was measured using a uniaxial tensile mechanical test. Histomorphometry analysis was performed to measure the average fascicle specific surface, fascicle size, and number of cells per unit area. Spearman's rank correlations of UTE-MRI biomarkers with mechanical and histomorphometry measures were investigated. The elastic modulus of ACL showed significant moderate correlations with UTE-Adiab-T1ρ (R = -0.59, p = 0.01), macromolecular fraction from MT modeling (R = 0.54, p = 0.01), magnetization transfer ratio (R = 0.53, p = 0.01), UTE-T2* (R = -0.53, p = 0.01), and average fascicle specific surface (R = 0.54, p = 0.01). UTE-MRI showed nonsignificant correlations with histomorphometry measures. UTE-MRI biomarkers may be useful noninvasive tools for the ACL mechanical assessment.

Comparison of Labrum Resistance Force while Pull-Probing In Vivo and Cadaveric Hips.

Cadaver tissue has been identified as the highest-fidelity anatomical representation in terms of the training for orthopedic surgery, including for arthroscopy of a damaged hip labrum. However, hip labrum stiffness in vivo and in cadavers has not been directly compared. The purpose of this study was to compare in vivo and cadaveric hip labrum stiffness during pull-probing with a force sensor. We measured the resistance force of the hip labrum in ten patients during hip arthroscopy (i.e., in vivo) and compared it with ten cadavers, both intact and detached from the acetabulum, using a surgical knife. We confirmed a partial labral tear (i.e., not detached fully from the rim) at an antero-superior potion in all of the patients. The mean highest resistance levels for the hip labrum in the patients (4.7 N) were significantly lower than the intact cadaveric labrum (8.3 N), and slightly higher than the detached labrum (4.2 N). In this study, the stiffness of the cadaveric labrum tissue was similar to that of the in-vivo hip labrum.

A Useful Combination of Quantitative Ultrashort Echo Time MR Imaging and a Probing Device for Biomechanical Evaluation of Articular Cartilage.

In this study, we combined quantitative ultrashort echo time (UTE) magnetic resonance (MR) imaging and an investigation by a probing device with tri-axial force sensor to seek correlations with mechanical properties of human patellar cartilage for in situ evaluation of biomechanical properties. Cartilage blocks (15 × 20 × 5 mm3) were dissected from the patella of six donors; 5 mm square regions of interest from the cartilage blocks were imaged using UTE-MR imaging sequences (T2* and magnetization transfer ratio (MTR)), and mechanical properties were measured using a micro indentation device. Then, the vertical reaction force on the cartilage surface was measured while push-probing forward 3 mm with the probing device at a 30° tilt to the horizontal plane. The results showed a positive correlation between stiffness/elastic modulus and each predictor variable (UTE-T2* (r = 0.240 and 0.255, respectively, UTE-MTR (r = 0.378 and 0.379, respectively), and probing device force (r = 0.426 and 0.423, respectively). Furthermore, multiple linear regression analysis showed the combination of the three predictors had stronger correlation (adjusted r2 = 0.314 (stiffness), 0.323 (elastic), respectively). Our results demonstrate the potential for these non- and less- invasive methods for in situ evaluation of the mechanical properties of cartilage tissue.

The Resistance Force of the Anterior Cruciate Ligament during Pull Probing Is Related to the Mechanical Property.

There are various methods for reconstructing the anterior cruciate ligament (ACL) from other muscles or tendons. Initial tension of the reconstructed ACL is one of the key elements affecting postoperative outcomes. However, tension cannot be measured after graft fixation. The only intraoperative assessment is pull probing, which is performed by pulling joint soft tissues with the arthroscopic probe and can be measured quantitatively. Therefore, its value might be used as an alternative value for the mechanical property of the ACL. Using a probing device one author developed to measure the resistance force of soft tissues quantitatively while probing, we measured the resistance force of dissected ACLs and used tensile testing to investigate the correlation between the resistance force and the mechanical property of the ligaments. According to the results, when a certain amount of tension (strain; 16.6%) was applied, its mechanical properties were moderately correlated (r = 0.56 [p = 0.045]) with the probing force. Therefore, the tension of the reconstructed ACL after fixation under real ACL reconstruction surgery can be derived from the value of the probing device.

Inclusion of the Acetabular Labrum Reduces Simulated Range of Motion of the Hip Compared With Bone Contact Models.

PURPOSE: To determine whether inclusion of the acetabular labrum affects the maximum range of motion (ROM) during simulation of the flexion-adduction-internal rotation impingement examination. METHODS: Three-dimensional surface reconstructions of the femur, hemi-pelvis, and labrum from computed tomography arthrography images of 19 participants were used to simulate maximum ROM during the flexion-adduction-internal rotation examination. Simulations were conducted for positions between 70° and 110° flexion and 0° and 20° adduction at 10° increments to measure maximum internal rotation and the position of contact between the femur and acetabular rim (bone-to-bone) or the femur and labrum (bone-to-labrum). Internal rotation angles and clock-face position values were compared between the 2 contact scenarios for each position. RESULTS: The ROM in the bone-to-labrum contact model was significantly less than that of the bone-to-bone contact model for all evaluated positions (P ≤ .001, except at 110° flexion and 20° adduction, P = .114). The inclusion of the labrum reduced internal rotation by a median [interquartile range] of 18 [15, 25]° while altering the position of contact on the acetabular clock-face by -0:01 [-0:27, 0:16]. The variability in contact location for the bone-to-labrum contact scenario was nearly double that of the bone-to-bone contact scenario, as indicated by the interquartile range. CONCLUSIONS: Inclusion of the anatomy of the acetabular labrum in collision models used to simulate impingement examinations reduced the internal rotation ROM by approximately 20° and increased variability in the location of contact relative to the acetabular rim. CLINICAL RELEVANCE: While standard bone-to-bone contact ROM simulations may be informative with respect to the relative change in ROM based on a surgical intervention (e.g., pre- and post-osteochondroplasty for cam-type femoroacetabular impingement), they may not accurately represent the clinical ROM of the joint or the kinematic position at which damage may occur due to shape mismatch between the femur and acetabulum.

A Probing Device for Quantitatively Measuring the Mechanical Properties of Soft Tissues during Arthroscopy.

Probing in arthroscopic surgery is performed by pulling or pushing the soft tissue, which provides feedback for understanding the condition of the soft tissue. However, the output is only qualitative based on the "surgeon's feeling". Herein is described a probing device developed to address this issue by measuring the resistance of soft tissues quantitatively with a tri-axial force sensor. Under both conditions (i.e., pull- and push-probing certain tissues mimicking the acetabular labrum and cartilage), this probing device is found to be useful for measuring some mechanical properties in joints during arthroscopy.

Sclerotic lesions of the femoral head-neck junction for diagnosis of femoroacetabular impingement.

The morphological characteristics associated with a diagnosis of femoroacetabular impingement (FAI) observed on plain radiographs can also be seen in subjects without hip joint symptoms. Therefore, the purpose of this study was to investigate whether sclerotic lesions on femoral head-neck junction (FHNJ) could be used as a supplemental diagnostic feature. A total of 128 hips from 119 patients (43 male and 76 female) diagnosed with FAI and 24 hips from 21 patients (2 male and 19 female) with other hip pathologies as control were compared in this study. Using standing frog-leg plain radiographs, the prevalence of sclerotic lesions on the FHNJ was established. Additionally, the pixel intensity (PI) of the sclerotic lesions between the FAI and the control groups were quantitatively compared. Sclerotic lesions were present in 96.1% of FAI hips (123 of 128) and only 37.5% of control hips (9 of 24) (p < 0.05). The ratio of PI in the FAI group was significantly higher (approximately 10%) than in the control group (p < 0.05). The evaluation of sclerotic lesions may be used as a supplement to aid in the diagnosis of FAI.

Quantitative evaluation of capsular and labral resistances in the hip joint using a probing device.

BACKGROUND: Probing to assess conditions of hip capsule and acetabular labrum is performed by "surgeons' feeling". OBJECTIVE: We investigated the resistance of the labrum and the hip capsule quantitatively while they were pulled with a probing device. METHODS: With the probing device in which a strain gauge was embedded, ten fresh frozen specimens of the pelvis and proximal femur were measured in each three surgical steps, (1) closed, (2) open, (3) closured for the capsule, and (1) intact, (2) cut, (3) repaired for the labrum. RESULTS: The mean highest resistance levels for the capsule were 9.8 N at the closed capsule, 4.1 N at the open capsule, and 8.5 N at the closured capsule. The values at the three phases were statistically significant. The mean highest resistance levels for the hip labrum were 8.2 N at the labrum intact, 4.0 N at the labrum cut, and 7.9 N at the labrum repair. The values at the three phases were also statistically significant. CONCLUSIONS: Since the quantitatively measured values in each three steps were significantly different, the values with the probing device might be useful to evaluate whether the lesion of the soft tissue exists and whether some surgical intervention works well.

Morphological abnormalities of the femur in the dysplastic hip. Relation between femur en acetabulum.

AIMS: To apply cutting edge geometry processing techniques and statistical shape modelling to perform a quali-tative and quantitive evaluation of femoral deformity in developmental hip dysplasia and to describe its relation to the amount of acetabular coverage in full 3D. An observational case-control study consisting of 40 right dysplastic cases compared to 43 normal hips, was designed. All subjects were Asian females with an average age of 53.9 years. The right femurs were scanned using computed tomography, followed by 3D reconstruction for statistical shape modelling. Inter- shape correspondences of the femoral shape were used to portray changes in femoral morphology to the amount of acetabular coverage. Partial least-squares regression was applied to establish a direct connection between acetabular coverage and the geometry of the femoral shape. Acetabular coverage accounted for 7.1% of variation in the overal femur shape (p<0.05). Significant changes in femoral morphology (p<0.05) were observed with decreasing acetabular coverage. The regression model demonstrated progressive shortening of the femur neck, as well as increasing attening of the femur head. Further, analysis of curvature and normal displacement demonstrated significant (p<0.05) flat- tening of the femur head especially in the area of the head-neck junction with increasing severity of acetabular dysplasia. Anatomic abnormalities inherent to the dysplastic hip are limited to the very proximal part of the femur and significantly increase when the acetabular coverage decreases. Flattening of the femur head is most pronounced at the peripheral part of the head, in specific the femoral head-neck region.

Evaluation of the efficacy of Ajuga decumbens extract supplement in individuals with knee discomfort associated with physical activity: A randomized, double-blind, placebo-controlled study.

The aim of the present study was to assess the efficacy and safety of the oral administration of Ajuga decumbens extract (ADE) supplement to individuals with knee discomfort associated with physical activity. A randomized, double-blind, placebo-controlled study was conducted using 48 subjects. The subjects were randomly allocated to an ADE diet group (oral administration of ADE-containing diet, n=24) or a placebo group (n=24), and the intervention was conducted for 12 weeks. A total of 22 subjects in the placebo group and 22 subjects in the ADE diet group were assessed to be eligible for assessment of the efficacy of supplement. Knee function was assessed by changes in the scores of the Japanese Knee Osteoarthritis Measure (JKOM) questionnaire and the scores of the Japan Orthopedic Association (JOA) criteria, as well as by analyzing the levels of type II collagen synthesis and degradation biomarkers (procollagen II C-terminal propeptide, cross-linked C-telopeptide of type II collagen, collagen type II cleavage and matrix metalloproteinase-13). Outcomes were measured at the baseline and at 4, 8 and 12 weeks from the start of administration. Subscale II (joint flexion/stiffness) of the JOA criteria was markedly improved in the ADE diet group compared with the placebo group at 8 and 12 weeks during the intervention. Furthermore, in the subgroup analyses using subjects with mild knee discomfort, subscale II (pain/stiffness) and IV (general activities) scores of JKOM were significantly improved (P<0.05) and total JKOM score was markedly improved in the ADE diet group compared with the placebo group at week 8 of the intervention. No adverse effects were identified for the administration of ADE. In conclusion, these observations suggest that the administration of an ADE-containing diet is safe and improves joint function (flexion and stiffness) and general activity in subjects with mild knee discomfort. Therefore, ADE could be a promising candidate as a functional food that is beneficial to joint health.

Hip Arthroscopy Capsular Closure: The Figure of Eight Technique.

Hip arthroscopy techniques have continued to evolve for femoroacetabular impingement and other intra-articular pathologies. However, there is still debate about the importance and technique of routine capsular closure. We present an efficient and reliable technique for creating a watertight capsular closure to prevent iatrogenic macro and microinstability. This Technical Note details our stepwise technique using figure of eight sutures to obtain a complete and secure capsular closure.

Prophylactic bioactive screw fixation as an alternative augmentation for femoroplasty.

Femoroplasty is theoretically a prophylactic surgical procedure for femoral neck fracture. Although bone cement is generally used for augmentation, its distribution cannot be easily controlled. This study investigated whether a bioactive screw is feasible for femoroplasty as an alternative augmentation material. A mechanical test was done to compare the strength of four types of augmentation bioactive screw (Superfixsorb), two bioinert cements, or no intervention in a composite femoral bone. The peak load to fracture under simulated falling was compared among the four groups. The mean peak load to failure in the bioactive screw group (2667 N) was significantly higher than that in the intact group (2391 N) (p=0.028), comparable to that in the Simplex P cement group (2864 N) (p=0.11), and significantly lower than that of the cranioplastic cement group (3022 N) (p=0.006). The strength of a composite femur with the bioactive screw was higher than that of an intact bone and comparable to one cement augmentation. Thus, this bioactive screw can be potentially used as augmentation material for femoroplasty.

Sagittal gap balancing with the concept of a single radius femoral component in posterior cruciate sacrificing total knee arthroplasty with patient-specific instrumentation.

PURPOSE: Sagittal gap balancing (relation between flexion and extension gaps) with placement of trial femoral components and reduction of the patella in total knee arthroplasty (TKA) is important, but it is not easy. The purpose of this study was to investigate whether (1) the flexion and extension gaps were equal when a previously suggested three-dimensional planning for a single-radius femoral component (its sagittal centre is matched with flexion-extension axis of knee movement) is executed with patient-specific instrumentation (PSI) and whether (2) PSI was done with good accuracy, which did not affect the first purpose. METHODS: Posterior cruciate ligament sacrificed (PS) TKA was performed on 12 joints. Using the patients' pre-operative computed tomography (CT) images, PSI was manufactured to fit on the bony surface of the knee joint and to simultaneously transfer pre-operative planning to the operating room. After osteotomy with PSI, gap measurements were calculated with the knee in flexion and extension. Angle deviations of both components were investigated with postoperative CT images. RESULTS: The flexion gap (mean, 19.1 mm) was larger than the extension gap (mean, 12.3 mm) in all cases. Angle differences between pre- and postoperative alignments were within 3° in all cases. CONCLUSIONS: Although PSI executed the pre-operative planning with good accuracy, the flexion gap is always larger than the extension gap. This finding suggests that surgeons may not aim for equal gaps of flexion and extension in PS-TKA.

Accuracy of angle and position of the cup using computed tomography-based navigation systems in total hip arthroplasty.

OBJECTIVE: The objectives of this study were to evaluate the accuracy of computed tomography (CT)-based navigation and to investigate whether the level of surgeon experience affects the accuracy of cup positioning under navigation. METHODS: This study investigated 117 hips in 103 patients who underwent primary total hip arthroplasty (THA) by 7 surgeons using a CT-based navigation system. Pre- and postoperative CT images were matched using a volume registration technique. Postoperative cup angles and positions were then measured using the same pelvic coordinates, and results were compared for experienced and inexperienced surgeons. RESULTS: The mean absolute error of the cup angle was 1.8 ± 1.6° for inclination and 1.2 ± 1.1° for anteversion. The mean absolute errors of cup position were 1.9 ± 1.5 mm, 1.4 ± 1.2 mm, and 1.9 ± 1.3 mm on the x-, y- and z-axes, respectively. No significant differences in accuracy were identified between experienced and inexperienced surgeons. CONCLUSIONS: The absolute spatial error of cup position was ≤ 2 mm for each axis, and the angle error was ≤ 2° for the angles of inclination and anteversion. This navigation system could therefore help surgeons perform accurate cup placement irrespective of the surgeon's level of experience.

Anterior impingement test for labral lesions has high positive predictive value.

BACKGROUND: The anterior impingement test is intended to detect anterosuperior acetabular labral lesions. In patients treated for labral lesions its sensitivity is reportedly 95% to 100%, and in a small group of patients undergoing periacetabular osteotomy, its sensitivity was 59% and specificity 100%. However, the sensitivity, specificity, positive predictive value, and negative predict value of this test to detect these labral lesions in unselected patients with hip pain are unknown. QUESTIONS/PURPOSES: We investigated these four parameters (1) in unselected patients with hip pain, and (2) in three subgroups of patients with dysplasia, femoroacetabular impingement (FAI), and with an intact joint space. METHODS: We prospectively studied 69 patients (15 men and 54 women) with a mean age of 57.2 years (range, 27-81 years). One observer performed the anterior impingement test in all patients. We determined the presence or absence of an anterosuperior labral lesion with radial MRI in 107 hips (38 patients in both hips: 14 with pain, and 24 without pain). We also investigated the parameters in the three subgroups which consisted of 60 cases of dysplasia, 27 cases of FAI, and 80 cases with intact joint space; the third subgroup partially overlapped the first and second subgroups. RESULTS: The four parameters in all hips were 50.6% (45/89), 88.9% (16/18), 95.7% (45/47), and 26.7% (16/60), respectively. Parameters in the three subgroups were similar to those of all cases. CONCLUSIONS: Although the sensitivity of the anterior impingement test did not reach a sufficient level for detecting anterosuperior labral lesions, we believe the high positive predictive value makes the test useful. LEVEL OF EVIDENCE: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

The intraoperative gap difference (flexion gap minus extension gap) is altered by insertion of the trial femoral component.

A Tensor/Balancer device has been recently developed in order to assess soft tissue balancing in total knee arthroplasty (TKA) under more physiological conditions. This device allows us to measure the joint gap with a trial femoral component in place with the patella reduced. The purpose of this study was to clarify whether the placement of the component changes the intraoperative gap difference (flexion gap distance minus extension gap distance). We prospectively investigated the extension (0°) and flexion (90°) gaps in 73 posterior-stabilized TKAs under 30 lb of joint distraction force. Then, we compared the gap difference with and without the trial femoral component in place. Our results showed that the intraoperative gap difference with the trial femoral component in place was larger than the intraoperative gap difference without the trial component (p=0.00003; with the trial component: mean 4.7 mm (standard deviation (SD): 3.0mm); without the trial component: mean 2.7 mm (SD: 3.3mm)). We consider that the change in gap difference with or without femoral component was caused by a relative difference in the elasticity and/or tightness of the soft tissue in extension versus flexion. Surgeons should be aware of this effect of the femoral component when considering intraoperative soft tissue balancing which leads to postoperative stability of the knee joint consequently.