Naoyuki Ochiai

TISSUE ENGINEERING OF CARTILAGE USING A HYBRID SCAFFOLD OF SYNTHETIC POLYMER AND COLLAGEN

A biodegradable hybrid scaffold of synthetic polymer, poly (DL-lactic-co-glycolic acid) (PLGA), and naturally derived polymer, collagen, was prepared by forming collagen microsponges in the pores of PLGA sponge. This was then used as the three-dimensional scaffold for tissue engineering of bovine articular cartilage, both in vitro and in vivo. In vitro studies show that hybridization with collagen facilitated cell seeding in the sponge and raised seeding efficiency. Chondrocytes adhered to the collagen microsponges, where they proliferated and secreted extracellular matrices with time, filling the space within the sponge. Hematoxylin and eosin staining revealed that most of the chondrocytes after 4 weeks of culture, and almost all cell types after 6 weeks of culture, maintained their phenotypically rounded morphology. While new tissue formed, the scaffold degraded and lost almost 36.9% of its original weight after 10 weeks. Subcutaneous implantation studies in nude mice demonstrated more homogeneous tissue formation in hybrid sponge than in PLGA sponge. The new tissue formed maintained the original shape of the hybrid sponge. The synthetic PLGA sponge, serving as a skeleton, facilitated easy formation into desired shapes and provided appropriate mechanical strength to define the ultimate shape of engineered tissue. Incorporation of collagen microsponges facilitated cell seeding and homogeneous cell distribution and created a favorable environment for cellular differentiation. The hybrid sponge could therefore represent a promising candidate as a three-dimensional scaffold for articular cartilage tissue engineering.

Lumbar Intervertebral Disk Degeneration in Athletes

Background Several studies have reported that physical loading related to competitive sports activities is associated with lumbar intervertebral disk degeneration. However, the association between types of sports activities and disk degeneration has not been clarified. Hypothesis The frequencies of disk degeneration may vary with the competitive sport because of the different postures and actions specific to each sport. Study Design Cross-sectional study (prevalence); Level of evidence, 3. Methods Study participants were 308 well-trained university athletes (baseball players, basketball players, kendo competitors, runners, soccer players, swimmers) and 71 nonathlete university students (reference group). Disk degeneration was evaluated using T2-weighted magnetic resonance imaging. A self-reported questionnaire concerning low back pain was also conducted. Results The proportions of the participants who had disk degeneration among the baseball players (odds ratio, 3.23) and the swimmers (odds ratio, 2.95) were significantly higher than among the nonathletes using logistic regression analysis. When all patients were grouped together, the association between lifetime experience of low back pain and participants with disk degeneration was significant, and a linear association between the degree of severest low back pain experienced and participants with disk degeneration, analyzed by a Cochran-Mantel-Haenszel test, was also significant. Conclusion Continuous competitive baseball and swimming activities during youth may be associated with disk degeneration. Furthermore, the study indicates that the experience of severe low back pain might be a predictor of disk degeneration in youth. The authors hope that preventive measures and management to protect against disk degeneration and low back pain in athletes will be established by further studies based on these results.

Immunohistochemical demonstration of nerve fibers in the synovial fold of the human cervical facel joint

The role of the intra‐articular synovial fold as a source of facet joint pain is unclear, because the nature of nociceptive innervation in lumbar synovial folds is controversial, and there have been no such studies in cervical synovial folds. The present study aimed to demonstrate the presence of nerve fibers including nociceptive fibers in synovial folds of human cervical facet joints using immunohistochemistry. Synovial folds of cervical facet joints removed from patients undergoing cervical spine laminoplasty were analyzed immunohistochemically using antibodies to protein gene product 9.5, β III‐tubulin, substance P and calcitonin gene‐related peptide. Many nerve fibers immunoreactive for protein gene product 9.5 and β III‐tubulin were demonstrated both around blood vessels and as free fibers in the stroma of the synovial fold. Also, immunostaining showed the presence of free nerve fibers immunoreactive for substance P and calcitonin gene‐related peptide in the stroma. The presence of putative nociceptive fibers in cervical synovial folds supports a possible role for these structures as a source of cervical facet joint pain.

Feasibility of rehabilitation training with a newly developed wearable robot for patients with limited mobility

OBJECTIVE To investigate the feasibility of rehabilitation training with a new wearable robot. DESIGN Before-after clinical intervention. SETTING University hospital and private rehabilitation facilities. PARTICIPANTS A convenience sample of patients (N=38) with limited mobility. The underlying diseases were stroke (n=12), spinal cord injuries (n=8), musculoskeletal diseases (n=4), and other diseases (n=14). INTERVENTIONS The patients received 90-minute training with a wearable robot twice per week for 8 weeks (16 sessions). MAIN OUTCOME MEASURES Functional ambulation was assessed with the 10-m walk test (10MWT) and the Timed Up & Go (TUG) test, and balance ability was assessed with the Berg Balance Scale (BBS). Both assessments were performed at baseline and after rehabilitation. RESULTS Thirty-two patients completed 16 sessions of training with the wearable robot. The results of the 10MWT included significant improvements in gait speed, number of steps, and cadence. Although improvements were observed, as measured with the TUG test and BBS, the results were not statistically significant. No serious adverse events were observed during the training. CONCLUSIONS Eight weeks of rehabilitative training with the wearable robot (16 sessions of 90min) could be performed safely and effectively, even many years after the subjects received their diagnosis.

Evaluation of tibial rotational stability of single-bundle vs. anatomical double-bundle anterior cruciate ligament reconstruction during a high-demand activity — A quasi-randomized trial

The purpose of this study was to compare the tibial rotational stability of anatomical double-bundle anterior cruciate ligament reconstructed knees with single-bundle anterior cruciate ligament reconstructed knees during a high-demand activity. Total of 66 subjects, (22 with double-bundle anterior cruciate ligament reconstruction, 22 with single-bundle anterior cruciate ligament reconstruction, and 22 healthy control individuals) were examined in this study. Using a 9-camera motion analysis system, motion subjects were recorded performing during a drop landing and cutting. Using the point cluster technique, the internal-external tibial rotation of both knees was calculated. The mean maximum range of motion for each knee was evaluated for 3 groups (double-bundle group, single-bundle group, and control group). Clinical assessment, including Tegner score, Lysholm score, and knee arthrometric measurement, revealed restoration of the reconstructed knee stability with no differences between the two anterior cruciate ligament reconstruction groups. The results showed that both groups resulted in tibial rotation values that were significantly smaller than those in the intact legs and those in the healthy controls. There were no significant differences in tibial rotation between the DB group and the SB group. Therefore anatomical double-bundle reconstruction restores normal tibial rotation no more than single-bundle reconstruction during this high-demand dynamic activity. These results suggest a trend towards dynamic overcorrection after the ACL reconstruction.

Relationship Between Low Back Pain and Competitive Sports Activities During Youth

Background Low back pain is a significant problem not only for the adult, but also during youth. However, the relationship between low back pain during youth and the duration or types of competitive sports has not been clarified. Hypothesis Low back pain during youth is associated with the duration and types of competitive sports. Study Design Cross-sectional study; Level of evidence, 4. Methods Study participants were 4667 new university students who, from 2004 to 2006, answered a questionnaire concerning low back pain and their participation in competitive sports. The participants were divided into a “no” group (NO), a middle group (MID), and a high group (HI) based on the duration of participation in competitive sports. The answers to the questionnaire were analyzed using the Cochran-Mantel-Haenszel test. Furthermore, we selected students who had participated in the same sport for 5 or more years and categorized the students according to the type of sport. Differences in low back pain among the groups were analyzed using logistic regression with the NO group as the reference group. Results There were statistically significant linear associations in the NO, MID, and HI groups, with 50.0%, 61.8%, and 71.7%, respectively, of the students experiencing low back pain. Among the NO, MID, and HI groups, 4.4%, 5.7%, 9.6%, respectively, had experienced school absence due to low back pain; and 4.0%, 8.5%, and 14.6%, respectively had low back pain with associated lower extremity pain and numbness. All 8 sports groups that were analyzed had experienced low back pain significantly higher than the NO group, and the odds ratios differed by sport with the highest (3.8) for the volleyball group. Conclusion Excessive exposure to competitive sports activities during youth was associated with low back pain and symptoms in the lower extremities, with the severity varying with the sport. To reduce low back pain in youth, factors that may be causing low back pain, such as sport-specific postures and motions, need to be investigated.

RESULTS OF NERVE GRAFTING FOR INJURIES OF THE AXILLARY AND SUPRASCAPULAR NERVES

We report the results in 33 patients who had nerve grafting of the axillary or the suprascapular nerve or of both. There were 32 men and one woman; their mean age was 21 years and the average interval between injury and operation was three months. At a mean follow-up of 27 months, the deltoid had recovered to M3 or better in 23 of 30 patients (77%) and the infraspinatus in 18 of 25 patients (72%). Shoulder elevation had reached 120 degrees or more in 27 patients (82%), with external rotation of 30 degrees or more in 27 (82%). Twenty-six patients (79%) could reach to the top of their head with their hand. Recovery of muscle strength, range of movement and shoulder function were satisfactory when surgery was performed within four months of the injury. Early exploration and nerve grafting can lead to a good functional recovery, but thorough exploration and careful repair of both nerves are essential.

Lumbar Intervertebral Disk Degeneration in Elite Competitive Swimmers A Case Control Study

Background The majority of orthopaedic problems experienced by competitive swimmers are related to pain in the shoulder, low back, and knee. Three of 39 national swim team members were hampered in their performance due to lumbar disk herniation at an international competition in 2001. There has been no previous research into lumbar disk degeneration in elite competitive swimmers. Hypothesis Excessive competitive swimming activities accelerate lumbar disk degeneration. Study Design Case control study; Level of evidence, 3. Methods Fifty-six elite swimmers (high-load group, 35 men and 21 women; mean age, 19.6 years) and a control group of 38 university recreational level swimmers (low-load group, 24 men and 14 women; mean age, 21.1 years) were evaluated for lumbar disk degeneration using magnetic resonance imaging. We compared the prevalence of disk degeneration and the disk level between the 2 groups and further investigated the relationship among their symptoms, swimming styles, and disk degeneration. Results Thirty-eight (68%) elite swimmers and 11 (29%) controls had degenerated disks at various disk levels, and the prevalence was significantly greater in the elite swimmers (P = .0002). Comparison between the 2 groups of the prevalence of disk degeneration at each level revealed that the disk level of L5-S1 was significantly more frequently degenerated in the high-load group (P = .026). There was no significant relationship observed among the variables of low back pain symptoms, swimming strokes, and disk degeneration. Conclusion Excessive competitive swimming activities might exaggerate lumbar intervertebral disk degeneration, especially in the L5-S1 intervertebral segment. Keywords lumbar intervertebral disk; disk degeneration; swimming; sports

Rotating three-dimensional dynamic culture of adult human bone marrow-derived cells for tissue engineering of hyaline cartilage

The method of constructing cartilage tissue from bone marrow‐derived cells in vitro is considered a valuable technique for hyaline cartilage regenerative medicine. Using a rotating wall vessel (RWV) bioreactor developed in a NASA space experiment, we attempted to efficiently construct hyaline cartilage tissue from human bone marrow‐derived cells without using a scaffold. Bone marrow aspirates were obtained from the iliac crest of nine patients during orthopedic operation. After their proliferation in monolayer culture, the adherent cells were cultured in the RWV bioreactor with chondrogenic medium for 2 weeks. Cells from the same source were cultured in pellet culture as controls. Histological and immunohistological evaluations (collagen type I and II) and quantification of glycosaminoglycan were performed on formed tissues and compared. The engineered constructs obtained using the RWV bioreactor showed strong features of hyaline cartilage in terms of their morphology as determined by histological and immunohistological evaluations. The glycosaminoglycan contents per µg DNA of the tissues were 10.01 ± 3.49 µg/µg DNA in the case of the RWV bioreactor and 6.27 ± 3.41 µg/µg DNA in the case of the pellet culture, and their difference was significant. The RWV bioreactor could provide an excellent environment for three‐dimensional cartilage tissue architecture that can promote the chondrogenic differentiation of adult human bone marrow‐derived cells.

Tissue-engineered cartilage by in vivo culturing of chondrocytes in PLGA–collagen hybrid sponge

Abstract Bovine chondrocytes were isolated from the shoulder articular joints of a calf, seeded in biodegradable porous polymer scaffolds, and implanted subcutaneously in the dorsum of athymic nude mice to tissue engineer articular cartilage in vivo. Hybrid sponge of poly( dl -lactic-co-glycolic acid) (PLGA) and collagen was used as the porous scaffold with PLGA sponge and collagen sponge used as the controls. Chondrocytes were seeded in low (1×10 7 cells/ml) and high (5×10 7 cells/ml) densities. Before implantation, the scaffold-cell constructs were cultured in vitro for 1 week. The implants were harvested after in vivo incubation of 2, 4, 6, and 8 weeks. The PLGA–collagen hybrid sponge implants maintained their original shapes, as did the PLGA sponge, whereas the collagen sponge collapsed. The mechanically strong PLGA sponge functioned as a skeleton and prevented the embedded collagen sponge from collapsing. The implants were examined histochemically by haematoxylin and eosin staining, by safranin O/fast green staining, and immunohistochemically by anti-collagen type II antibody. The percent of cartilaginous extracellular matrices increased, while neovascularization decreased with an increased implantation period. A greater amount of homogeneous cartilaginous tissue formed when chondrocytes were seeded at a higher density. The morphology of chondrocytes, the expression of cartilaginous matrices in the PLGA–collagen hybrid sponge, was similar to those in collagen sponge. The cartilaginous matrices were more homogeneously distributed in the PLGA–collagen hybrid sponge and collagen sponge than in the PLGA sponge. Hybridization of the PLGA sponge and collagen sponge facilitated cell seeding and promoted the in vivo formation of cartilaginous tissue.