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During anterior cruciate ligament (ACL) reconstruction, even when a posterior wall of the femoral bone tunnel is identified, computed tomography (CT) occasionally demonstrates a breach of the posterior femoral cortex of the femoral bone tunnel, i.e., posterior wall blowout, after ACL reconstruction (posterior wall blowout-like phenomenon). This study aimed to investigate the influence of the posterior wall blowout-like phenomenon on clinical outcomes after ACL reconstruction using hamstring tendon.A total of 105 patients who underwent CT examination two weeks after ACL reconstruction were enrolled. A cortical suspension device was used for femoral side fixation in all cases. Posterior wall was identified in all cases during the surgery. The side-to-side difference in anterior knee laxity, pivot shift test, Lysholm knee score, the International Knee Documentation Committee (IKDC) subjective form, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were evaluated one year after the surgery. A second CT examination was performed 6-12 months after the surgery, if a posterior wall blowout-like phenomenon was identified in the first CT examination.Two weeks after the surgery, 16 of the 105 patients showed a posterior wall blowout-like phenomenon. Twelve of the 16 cases demonstrated a regenerated posterior femoral cortex of the femoral bone tunnel on their second CT images. There were no significant differences between the posterior wall blowout-like phenomenon group and the normal posterior wall group in terms of a side-to-side difference in anterior knee laxity (0.4 ± 1.5 mm and 0.1 ± 1.6 mm, respectively), pivot shift test, Lysholm knee score, IKDC score, and KOOS at one year after surgery. The length and diameter of the femoral bone tunnel were not significantly different between the two groups.Posterior wall blowout-like phenomenon after ACL reconstruction using a cortical suspension device did not negatively influence clinical outcomes.III - retrospective comparative clinical study.

Anterior cruciate ligament (ACL) injury is the most common traumatic injury to the knee joint. Suspensory fixation has become popular in ACL reconstruction because of its high primary stability, less invasiveness, and surgical convenience. There are two common types of suspensory fixation devices: those with fixed-length and those with adjustable-length loops. Owing to structural differences and differences in initial tensioning techniques, it is expected that mechanical property and damage to the tendons will vary from device to device; however, no literature has examined this so far. The main purpose of this study was to evaluate the damage caused to the tendon by three different suspensory fixation devices. An effective mechanical test was carried out as a prerequisite.First, the mechanical properties of simple loop device (SLD) as fixed-length loop device, first-generation, and second-generation adjustable devices (AD1 and AD2) as adjustable-length loop devices were tested (isolated device testing). Second, each device was tested using bovine extensor tendons (specimen testing). Cyclic testing included 2000 cycles; the devices were subsequently displaced until failure, and the ultimate tensile strength was determined using isolated device testing. Six samples of 3 devices were used in each testing experiment. After specimen testing, the surface structure of the tendon was evaluated quantitatively using optical coherence tomography (OCT) and our original histological scoring system.During isolated device testing, SLD demonstrated the least cyclic displacement, followed by AD1 and AD2. The highest ultimate tensile strength was observed in AD2, followed by SLD and AD1. In specimen testing, the least cyclic displacement was observed in SLD, followed by AD1 and AD2. Histologically, AD1 demonstrated a significantly lower score, with damaged surface morphology, than SLD and AD2. OCT values were significantly higher, with a more disturbing tendon surface structure, in AD1 than in SLD and AD2.The first-generation adjustable loop device exhibited greatest graft tissue damage at the suspensory site in a clinically relevant setting. The thinner adjustable loop mechanism may have elevated graft damage by frictional stresses during loop adjustment or by repetitive tensioning stresses.

Background Knee joint distraction (KJD) has received much attention as a joint preserving surgery, especially in young patients with advanced knee osteoarthritis (OA). Methods This study included 16 patients with advanced knee OA who underwent KJD combined with marrow stimulating techniques and were followed up for more than 2 years. The patients’ clinical scores, including the Japanese Orthopaedic Association (JOA) score, Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales, ROM, joint space width, and semiquantitative MRI were evaluated. The factors affecting clinical outcomes were analyzed. Results Postoperatively, the JOA score and the individual scores of the KOOS subscales improved significantly (JOA score: P = 0.0028, KOOS-symptoms: P = 0.0016, -pain: P = 0.0011, -ADL: P = 0.0009, -sports/recreation: P = 0.0144, and -QOL: P = 0.0034). Although the extension of the knee joint did not change throughout the follow-up period, flexion of the joint deteriorated at the time of device removal but recovered to the preoperative level at the final follow-up. Preoperative joint space width was 2.4 ± 2.0 mm and at the final follow-up, it increased to 3.3 ± 1.5 mm, showing statistically significant improvement (P = 0.034). The postoperative semiquantitative MRI score also improved significantly (from 6.0 ± 3.0 to 42.1 ± 28.7, P = 0.0001). A high BMI was associated with a poor clinical outcome. Conclusion Although the effect of marrow stimulating techniques for cartilage repair was not well clarified and the complication rate was high, the clinical and radiographic outcomes showed significant improvement after KJD combined with marrow stimulating techniques in patients with advanced knee OA. However, we should be careful about suggesting this procedure in obese patients.

To investigate factors that influence the prevalence of articular cartilage injury in patients with anterior cruciate ligament (ACL) injury. This multicentre study included patients with ACL injury. Logistic regression analysis was conducted to identify factors that influence the prevalence of cartilage injury during ACL reconstruction. A total of 811 patients were enrolled. The factors that significantly influenced the prevalence of cartilage injury were age (odds ratio [OR], 1.04; P = 0.000), a positive pivot shift test result (OR, 1.43; P = 0.021), medial meniscal injury (OR, 2.55; P = 0.000), and delayed surgery (≥ 12 months) (OR, 2.52; P = 0.028) in the medial compartment of the knee; age (OR, 1.05; P = 0.000), subjective grades of apprehension during the pivot shift test (OR, 1.46; P = 0.010), lateral meniscal injury (OR, 1.98; P = 0.003), femoro-tibial angle (FTA) (OR, 0.92; P = 0.006), and delayed surgery (≥ 12 months) (OR, 2.63; P = 0.001) in the lateral compartment; and age (OR, 1.06; P = 0.000), body mass index (OR, 1.07; P = 0.028), a positive pivot shift test result (OR, 1.60; P = 0.018), FTA (OR, 0.90; P = 0.006), and delayed surgery (≥ 12 months) (OR, 3.17; P = 0.008) in the patellofemoral compartment. An older age, a longer duration between injury and surgery, and a positive pivot shift test result were positively associated with the prevalence of cartilage injury in three compartments in patients with ACL injuries. Early ACL reconstruction is recommended to prevent cartilage injury. Level III.

Intra-articular synovial haemangioma of the knee is a benign tumour. However, diagnostic delay leads to degenerative changes in the cartilage and osteoarthritis due to recurrent haemarthrosis. Therefore, treatment should be performed immediately. We report the case of a localized synovial haemangioma arising from the medial plica in a 38-year old female presenting with pain and restricted range of motion in the right knee joint. Initially, we diagnosed this case as a localized pigmented villonodular synovitis (LPVS) based on MRI and arthroscopic findings and performed only arthroscopic en bloc excision of the mass and synovectomy around the mass for diagnostic confirmation. Fortunately, there was no difference in the treatment approaches for LPVS and localized haemangioma and the synovial haemangioma had not recurred at the 3-month postoperative follow-up with MRI. The patient's clinical symptoms resolved and had not relapsed two years after surgery.

The present study investigated intra-articular injection of bone-marrow-derived mesenchymal stem cells (MSCs) combined with articulated joint distraction as treatment for osteochondral defects. Large osteochondral defects were created in the weight-bearing area of the medial femoral condyle in rabbit knees. Four weeks after defect creation, rabbits were divided into six groups: control group, MSC group, distraction group, distraction + MSC group, temporary distraction group, and temporary distraction + MSC group. Groups with MSC received intra-articular injection of MSCs. Groups with distraction underwent articulated distraction arthroplasty. Groups with temporary distraction discontinued the distraction after 4 weeks. The rabbits were euthanized at 4, 8, and 12 weeks after treatment except temporary distraction groups which were euthanized at only 12 weeks. Histological scores in the distraction + MSC group were significantly better than in the control, MSC group or distraction group at 4 and 8 weeks, but showed no further improvement. At 12 weeks, the temporary distraction + MSC group showed the best results, demonstrating hyaline cartilage repair with regeneration of the osteochondral junction. In conclusion, joint distraction with intra-articular injection of MSCs promotes early cartilage repair, and compressive loading of the repair tissue after temporary distraction stimulates articular cartilage regeneration.

Background The purpose of this study was to evaluate the functional and radiographic outcome of fixation of unstable juvenile osteochondritis dissecans lesions of the knee after a minimum of 2 years of follow-up. Methods A total of 33 unstable juvenile osteochondritis dissecans lesions in 30 patients underwent fixation using bioabsorbable pins through arthrotomy or under arthroscopy. The patients consisted of 23 males and 7 females, and the average age at the time of operation was 14.4 years (range, 11 to 17 y). The functional outcomes were evaluated using the Lysholm score and Hughston's criteria at a mean follow-up of 3.3 years (range, 2.1 to 6.3 y). Healing of the osteochondritis dissecans lesions were confirmed by plain radiographs and magnetic resonance imaging. Results The Lysholm score improved significantly at 3 months after the surgery, and was maintained until the final follow-up. Radiographically, 32 of 33 lesions healed after fixation of the lesion (healing rate was 97.0%). Healing was achieved at an average of 2.4 months on plain radiographs and 4.2 months on magnetic resonance imaging. According to Hughston's criteria, 25 patients were graded as excellent, 4 as good, and 1 as poor at the final follow-up. Conclusions The fixation of the unstable juvenile osteochondritis dissecans lesions with bioabsorbable pins demonstrated improved clinical outcomes and radiographic high healing rates at a mean of 3.3 years of follow-up. We advocate this procedure for patients with unstable juvenile osteochondritis dissecans lesions of sufficient quality to enable fixation which will preserve the normal contour of the distal femur. Level of evidence Level IV-retrospective case series.

A new cell delivery system using magnetic force, termed magnetic targeting, was developed for the accumulation of locally injected cells in a lesion. The aim of this study was to assess the safety and efficacy of mesenchymal stem cell (MSC) magnetic targeting in patients with a focal articular cartilage defect in the knee. MSC magnetic targeting for five patients was approved by the Ministry of Health Labour and Welfare of Japan. Autologous bone marrow MSCs were cultured and subsequently magnetized with ferucarbotran. The 1.0-T compact magnet was attached to a suitable position around the knee joint to allow the magnetic force to be as perpendicular to the surface of the lesion as possible. Then 1 × 107 MSCs were injected into the knee joint. The magnet was maintained in the same position for 10 min after the MSC injection. The primary endpoint was the occurrence of any adverse events. The secondary endpoints were efficacy assessed by magnetic resonance imaging (MRI) T2 mapping and clinical outcomes using the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation and the Knee Injury and Osteoarthritis Outcome Score (KOOS). No serious adverse events were observed during the treatment or in the follow-up period. Swelling of the treated knee joint was observed from the day after surgery in three of the five patients. The swelling resolved within 2 weeks in two patients. MRI showed that the cartilage defect areas were almost completely filled with cartilage-like tissue. MOCART scores were significantly higher 48 weeks postoperatively than preoperatively (74.8 ± 10.8 vs 27.0 ± 16.8, p = 0.042). Arthroscopy in three patients showed complete coverage of their cartilage defects. Clinical outcome scores were significantly better 48 weeks postoperatively than preoperatively for the IKDC Subjective Knee Evaluation (74.8 ± 17.7 vs 46.9 ± 17.7, p = 0.014) and knee-related quality-of-life (QOL) in the KOOS (53.8 ± 26.4 vs 22.5 ± 30.8, p = 0.012). Magnetic targeting of MSCs was safely performed and showed complete coverage of the defects with cartilage-like tissues and significant improvement in clinical outcomes 48 weeks after treatment. The magnetic targeting of MSCs is useful as a minimally invasive treatment for cartilage repair. IV.

Objective The aim of this study was to evaluate an intraarticular injection of different doses of autologous mesenchymal stem cells (MSCs) for improving repair of midterm osteochondral defect. Design At 4 weeks postoperative marrow stimulation model bilaterally (3 mm diameter; 4 mm depth) in the medial femoral condyle, autologous MSCs were injected into knee joint. Twenty-four Japanese rabbits aged 6 months were divided randomly into 4 groups ( n = 6 per group): the control group and and MSC groups including 0.125, 1.25, and 6.25 million MSCs. Repaired tissue was assessed macroscopically and histologically at 4 and 12 weeks after intraarticular injection of MSCs. Results At 12 weeks, there was no repair tissue in the control group. The gross appearance of the 1.25 and 6.25 million MSC groups revealed complete repair of the defect with white to pink tissue at 12 weeks. An osteochondral repair was histologically significantly better in the 1.25 and 6.25 million MSC groups than in the control and 0.125 million MSC groups at 4 and 12 weeks, due to presence of hyaline-like tissue in the deep layer at 4 weeks, and at 12 weeks hyaline cartilage formation at the periphery and fibrous tissue containing some chondrocytes in the deep layer of the center of the defect. Subchondral bone was restructured in the 1.25 and 6.25 million MSC groups, although it did not resemble the normal bone. Conclusion An intraarticular injection of 1.25 or 6.25 million MSCs could promote the repair of subchondral bone, even in the case of midterm osteochondral defect.

Various cartilage injury treatments such as bone marrow–stimulating techniques and autologous osteochondral grafting have been described. Good clinical results have been attained with these methods for small cartilage injuries. However, these methods are controversial for larger lesions. In 1994, Brittberg et al first reported on the clinical results after autologous chondrocyte implantation using a monolayer culture to repair cartilage injury. Although their surgical procedure heralded a breakthrough in the field of cartilage repair, various potential problems have been identified such as chondrocyte leakage from the defect site, chondrocyte dedifferentiation, and potential uneven distribution of grafted chondrocytes. Despite good clinical results, re-creation of a 3-dimensional zonal architecture of chondrocytes in repair tissue has remained elusive. Lastly, a multicenter report by Zaslav et al delineated high rates of secondary surgical procedures relating to periosteal detachment, periosteal overgrowth, and adhesions. Newer technical improvements in cell selection, surgical technique as well as scaffold development have recently been reported. This article describes these technical enhancements including the use of collagen patch, second-generation cell growth on scaffolds, cultured chondrocytes embedded in Atelocollagen gel, and a fourth-generation arthroscopic gel chondrocyte implantation in a 3-dimensional fibrin gel. Further longitudinal study will hopefully show improved long-term structural results from these enhancements over time.

AbStrA ct Aim: until recently, only fibrin glue has been available for clinical usage to repair articular cartilage, although its adhesiveness is not strong enough for use with articular cartilage, and it is derived from human blood and thus carries the risk of contamination. recently, LYdEX, a new biodegradable hydrogel glue, has come onto the market. t he purpose of this study was to evaluate the adhesive strength and cytotoxicity of LYdEX when used on articular cartilage. Materials and Methods: t he differing adhesive strengths of collagen membrane and articular cartilage with LYdEX versus with fibrin glue were measured using a tensile tester. In addition, the cytotoxity of LYdEX in vitro was evaluated. t he cytotoxity of LYdEX for the articular cartilage of rats was evaluated histopathologically. Results: t he adhesive strength of LYdEX was significantly stronger than that of fibrin glue, giving values about 3.8 times higher. LYdEX has no discernible effect on normal articular cartilage. Conclusions: our study is the first to assess the usefulness and safety of LYdEX for use on articular cartilage.

Skeletal muscle injuries often leave lasting functional damage or pain. Muscle injuries are routinely treated conservatively, but the most effective treatment to promote the repair of injured muscles has not yet been established. Our previous report demonstrated that human peripheral blood-derived CD133(+) cell transplantation to rat skeletal muscle injury models inhibited fibrosis and enhanced myogenesis after injury. However, the acquisition of a sufficient number of cells remains the limitation for clinical application, as the CD133(+) population is rare in human blood. In this study, we applied a magnetic cell targeting system to accumulate transplanted cells in the muscle injury site and to enhance the regenerative effects of CD133(+) cell transplantation, focusing on the fact that CD133(+) cells are labeled with a magnetic bead for isolation. For the magnetic cell targeting, the magnet field generator was set up to adjust the peak of the magnetic gradient to the injury site of the tibialis anterior muscle, and 1×10(4) human peripheral blood CD133(+) cells were locally injected into the injury site. This cell number is 10% of that used in the previous study. In another group, the same number of CD133(+) cells was injected without magnetic force. The CD133(+) cells transplanted with the magnetic force were more accumulated in the muscle injury site compared with the CD133(+) cells transplanted without the magnetic force. In addition, the transplantation of CD133(+) cells under the magnetic control inhibited fibrous scar formation and promoted angiogenesis and myogenesis, and also upregulated the mRNA expression of myogenic transcription factors, including Pax7, MyoD1 and Myogenin. However, the transplantation of CD133(+) cells without the magnetic force failed to demonstrate these effects. Thus, our magnetic cell targeting system enables transplantation of a limited number of CD133(+) cells to promote the repair of skeletal muscle injury.

Background: Cell therapies are hampered by the difficulty of delivering cells to and retaining them in target tissues long enough to repair or regenerate local tissues. Hypothesis: Magnetic-assisted delivery of magnetically labeled mesenchymal stem cells (m-MSCs) would be rapid, allowing for chondrogenic differentiation and functional joint repair without replacement. Study Design: Controlled laboratory study. Methods: Sixteen mini-pigs aged 6 to 7 months were used. A full-thickness cartilage defect was created in the center of the patella with a cylindrical punch (diameter, 6 mm). At 4 weeks after creation of the cartilage defects, the animals were divided into 3 treatment groups: In the M group, m-MSCs (5 × 106 cells) were injected and accumulated to the cartilage defect using an external magnetic force (1.5 T) for 10 minutes; in the G group, the patella was faced upward, filled with MSCs (5 × 106 cells), and held for 10 minutes; and in the C group, only phosphate-buffered saline was injected. The regenerated cartilage was evaluated in 5 knees in each of the 3 groups by arthroscopic surgery at 6 and 12 weeks and histological and ultrasound evaluation at 12 and 24 weeks. Results: The mean arthroscopic scores at 6 weeks were 10.4 ± 1.10 in the M group, 8.8 ± 0.84 in the G group, and 7.4 ± 0.89 in the C group. There was a statistically significant difference between the M group and the other 2 groups. The mean arthroscopic scores at 12 weeks were 12.8 ± 1.30 (M group), 10.5 ± 1.30 (G group), and 9.5 ± 0.58 (C group), with a statistically significant difference between the M and C groups. The mean histological scores using the Wakitani scoring system at 12 weeks were 2.8 ± 0.96 (M group), 5.4 ± 0.55 (G group), and 6.0 ± 2.20 (C group), and the mean histological scores at 24 weeks were 2.4 ± 1.50 (M group), 3.5 ± 0.56 (G group), and 5.3 ± 1.50 (C group). The mean histological scores at 12 weeks were significantly better in the M group than in the other groups, and the M group maintained a significantly better histological score than did the C group at 24 weeks. Conclusion: The m-MSCs had no adverse effect on chondrogenic differentiation, and m-MSCs delivered by magnetic field application repaired cartilage defects. Clinical Relevance: The clinical application of this novel stem cell delivery system is a potential therapeutic option for treating cartilage defects and may be more applicable throughout the body than traditional methods.

Mesenchymal stem cells (MSCs) are an attractive option for tissue repair, but scar tissue and loose bodies occur if we use a large number of cells to treat tissue injury. In 2008, Ochi developed a new cell delivery system using MSCs labeled with supraparamagnetic iron oxide and external magnetic force and succeed the effective accumulation of MSCs to the tissue injury site. This system was applied for cartilage, bone and muscle injury in animal models and better tissue regeneration was obtained than using MSCs injection only. Our new cell delivery system with m-MSCs and an external magnetic force has the potential to become a novel therapeutic option for tissue regeneration in the foreseeable future.

The aim of this study was to investigate a cell delivery system for repair of severe chronic osteochondral defects using magnetically labeled mesenchymal stem cells (m-MSCs), with the aid of an external magnetic device, through the accumulation of a small number of m-MSCs into a desired area and to detect the suitable number of autologous m-MSCs needed for repair of the defect. Twenty-six male Japanese white rabbits aged 6 months were used. An osteochondral defect was created bilaterally at the weight-bearing surface of the medial femoral condyle of the rabbits' knees (3 mm diameter; 4 mm depth). At 4 weeks after creation of the defect, autogenic transplantation of the m-MSCs into the defect area was performed, followed by 10-min exposure to an external magnetic device, where animals were divided into four groups: high (1 × 106 m-MSCs), medium (2 × 105 m-MSCs), low (4 × 104 m-MSCs), and control (PBS injection). At 4 and 12 weeks posttransplantation of m-MSCs, repaired tissue was assessed histologically using the Fortier score with toluidine blue staining. Transplantation of a low number of m-MSCs was not enough to improve osteogenesis and chondrogenesis, but the medium and high groups improved repair of the chronic defect with chondrogenic tissues and showed histologically significantly better results than the control and low groups. The use of a magnetic targeting system for delivering m-MSCs has the potential to overcome the clinical hurdles for repair of the severe chronic osteochondral defect. Furthermore, this system is predicted to produce good clinical outcomes for humans, not only to repair osteochondral defects but also to repair a variety of damaged tissues.

Background A symptomatic bipartite patella is rarely seen in athletic adolescents or young adults in daily clinical practice. To date, only a limited number of studies have focused on patellofemoral alignment. The current study revealed a unique patellofemoral alignment in a patient with a symptomatic bipartite patella. Methods Twelve patients with 12 symptomatic bipartite patellae who underwent arthroscopic vastus lateralis release (VLR) were investigated (10 males and two females, age: 15.7±4.4years). The radiographic data of contralateral intact and affected knees were reviewed retrospectively. From the lateral- and skyline-view imaging, the following parameters were measured: the congruence angle (CA), the lateral patellofemoral angle (LPA), and the Caton–Deschamps index (CDI). As an additional parameter, the bipartite fragment angle (BFA) was evaluated against the main part of the patella in the skyline view. Results Compared with the contralateral side, the affected patellae were significantly medialized and laterally tilted (CA: P =0.019; LPA: P =0.016), although there was no significant difference in CDI ( P =0.877). This patellar malalignment was found to significantly change after VLR (CA: P =0.001; LPA: P =0.003) and the patellar height was significantly lower than in the preoperative condition ( P =0.016). In addition, the BFA significantly shifted to a higher degree after operation ( P =0.001). Conclusions Patients with symptomatic bipartite patellae presented significantly medialized and laterally tilted patellae compared with the contralateral intact side. This malalignment was corrected by VLR, and the alignment of the bipartite fragment was also significantly changed. Level of evidence: Level IV, case series

Cell sheet engineering has developed as a remarkable method for cell transplantation. In the field of cartilage regeneration, several studies previously reported that cartilage defects could be regenerated by transplantation of a chondrocyte sheet using cell sheet engineering. However, it remains unclear how such a thin cell sheet could repair a deep cartilage defect. We, therefore, focused on the mechanism of cartilage repair using cell sheet engineering in this study. Chondrocyte sheets and synovial cell sheets were fabricated using cell sheet engineering, and these allogenic cell sheets were transplanted to cover an osteochondral defect in a rat model. Macroscopic and histological evaluation was performed at 4 and 12 weeks after transplantation. Analysis of the gene expression of each cell sheet and of the regenerated tissue at 1 week after transplantation was performed. In addition, green fluorescent protein (GFP) transgenic rats were used as donors (transplanted chondrocyte sheets) or recipients (osteochondral defect models) to identify the cell origin of regenerated cartilage. Cartilage repair was significantly better in the group implanted with a chondrocyte sheet than in that with a synovial cell sheet. The results of gene expression analysis suggest that the possible factor contributing to cartilage repair might be TGFβ1. Cell tracking experiments using GFP transgenic rats showed that the regenerated cartilage was largely composed of cells derived from the transplanted chondrocyte sheets.

The present study investigated intra-articular injection of bone-marrow-derived mesenchymal stem cells (MSCs) combined with articulated joint distraction as treatment for osteochondral defects. Large osteochondral defects were created in the weight-bearing area of the medial femoral condyle in rabbit knees. Four weeks after defect creation, rabbits were divided into six groups: control group, MSC group, distraction group, distraction + MSC group, temporary distraction group, and temporary distraction + MSC group. Groups with MSC received intra-articular injection of MSCs. Groups with distraction underwent articulated distraction arthroplasty. Groups with temporary distraction discontinued the distraction after 4 weeks. The rabbits were euthanized at 4, 8, and 12 weeks after treatment except temporary distraction groups which were euthanized at only 12 weeks. Histological scores in the distraction + MSC group were significantly better than in the control, MSC group or distraction group at 4 and 8 weeks, but showed no further improvement. At 12 weeks, the temporary distraction + MSC group showed the best results, demonstrating hyaline cartilage repair with regeneration of the osteochondral junction. In conclusion, joint distraction with intra-articular injection of MSCs promotes early cartilage repair, and compressive loading of the repair tissue after temporary distraction stimulates articular cartilage regeneration.

The current patients required high flexion total knee arthroplasty (TKA). We hypothesized the patients who would get the high rotational angle just after TKA could gain high flexion knee 1 year after TKA. Sixty-three patients (average age: 70.6 years) were examined. In order to examine between the intraoperative rotational angles and the gained flexion angles after TKA, the patients were divided into two groups: the H group (more than 120°) and the L groups (less than 120°) by the gained flexion angles. The relationship between the flexion angles at 1 year after surgery and the intraoperative rotational angle had no significant correlation. But the rotational angles in the L group tended to be higher than the ones in the H group, and at only 30°, the L group gained significantly more rotational angle than the H group. These results might show that a tighter rotational stability induces a gain of higher flexion knee after TKA.

Cells, scaffold, and growth factors are crucially important in regenerative medicine and tissue engineering. Progress in science and technology has enabled development of these three factors, with basic research being applied clinically. In the past decade, we have investigated tissue regeneration in animal models of musculoskeletal disorders by using cells, scaffold, and delivery systems which has been relatively easy to apply and develop in clinical settings. Moreover, microRNA (miRNA), which are important in biological processes and in the pathogenesis of human diseases, have been used in research on regenerative medicine. For the cell source, we focused on mesenchymal stem cells (MSC) and CD34+ and CD133+ cells as endothelial progenitor cells for regeneration of musculoskeletal organs. These cells are accessible and safe. For less invasive and more effective therapy, we developed a novel cell-delivery system using magnetic force to accumulate cells at a desired site. Furthermore, administration of synthetic miRNA could enhance tissue regeneration. In our studies, use of these cells combined with a cell-delivery system, miRNA, scaffold, and cytokines has led to effective regeneration of musculoskeletal tissues including cartilage, bone, ligaments, muscle, peripheral nerves, and spinal cord. The current and future objective is more effective and less invasive cell-based therapy with spatial control of transplanted cells by use of an external magnetic force. Analysis of efficiency, safety, and the mechanism of tissue regeneration by cells, scaffold, and miRNA will lead to more promising regenerative medicine, involving the development of a new generation of therapy. This review will focus on our regenerative medicine research, which focuses on clinical application of cells, scaffold, and miRNA.

Multiple epiphyseal dysplasia (MED) is one of the common forms of skeletal dysplasia characterized as epiphyseal dysplasia, with an endosomal dominant inheritance pattern causing an altered enchondral ossification affecting epiphyseal ossification centres [1e3]. Fairbank in 1935 reported a severe form of MED (Fairbank type) with considerable involvement of the wrist and hand for the first time. In 1937 Ribbing reported a milder type (Ribbing type) with or without minimal involvement of the wrist and hand for the first time [2,4,5]. The typical features of this disease are delayed and irregular ossification of epiphyses and early onset of osteoarthritis, mainly affecting the hip and knee joints. The diagnosis is based on radiographic findings, family history and gene mutation [6e8]. Genetically, it is fairly heterogeneous with mutation in COL9A1, COL9A2, COL9A3, COMP, DTDST and MATN3 capable of causing the clinical feature of MED [9]. The radiographic findings of a hip joint with MED are often confused with those of Perthes disease. Because misdiagnosis leads to overtreatment such as orthosis and innominate osteotomy, we should be discerning in our diagnosis of MED [10]. As for the knee joint, a shallow femoral trochlear groove, flattened femoral condyle and flatness of intercondylar eminence are seen after epiphyseal closure, and irregularity and

Far antero-medial (FAM) portal technique is usually used in our department in anterior cruciate ligament (ACL) reconstruction when drilling the femoral tunnel. Although the FAM portal technique carries potential risks, such as cartilage injury of the lateral femoral condyle, peroneal nerve injury and blow out of the lateral femoral condyle's posterior wall, these problems were resolved in a cadaveric study, in which 110°–120°knee flexion was recommended when drilling the femoral tunnel. However, there is a potential risk of injuring the cartilage of the medial femoral condyle especially when drilling the postero-lateral bundle. A new method is proposed to ensure that the femoral tunnel drilling does not damage the cartilage of the medial femoral condyle.

The purposes of this study were to evaluate early- to midterm clinical results after implantation of tissue-engineered cartilage-like tissue for the treatment for full-thickness cartilage defects of the knee and to identify the factors affecting the final clinical results. Tissue-engineered cartilage-like tissue was prepared by culturing autologous chondrocytes in atelocollagen gel for 3–4 weeks. A total of 73 knees of 72 patients with full-thickness cartilage defects were implanted with this tissue-engineered cartilage-like tissue. The follow-up of these patients for >5 years (range 5–11 years, median 8.0 years) is reported. The patients were evaluated clinically using a rating scale, as well as arthroscopically, biomechanically, and histologically. A modified magnetic resonance observation of cartilage repair tissue (MOCART) system was used to quantify the magnetic resonance imaging (MRI) findings of the lesions. The patient or defect factors influencing the final clinical outcomes were also investigated. Clinical rating improved significantly after implantation of tissue-engineered cartilage-like tissue. Arthroscopic findings at 2 years after implantation were graded as normal or nearly normal according to the International Cartilage Repair Society (ICRS) scale in 64 of 73 knees (87.7 %). Biomechanically, stiffness of the graft almost equalled the surrounding normal cartilage (87.9–102.5 %) at 2 years after implantation. Histologically, overall assessment of the repaired tissue by ICRS Visual Assessment Scale II was 70.4 ± 20.8. The average MOCART score was 13.5 ± 11.3 (0–45) preoperatively, 66.6 ± 16.8 (10–90) at 1 year after implantation, 70.4 ± 16.1 (15–90) at 2 years after implantation, and 72.5 ± 17.4 (15–95) at the final follow-up, indicating that MRI results were maintained. Among the factors investigated, only arthroscopic grade of the repaired lesion at 2 years after implantation was significantly correlated with the final clinical scores. Implantation of tissue-engineered cartilage-like tissue for the cartilage defects of the knee was effective in short- to midterm post-operatively. This procedure can be proposed as one option for repairing full-thickness cartilage defect of the knee. IV.

Background It is difficult for an articular cartilage injury to repair spontaneously. There are many procedures for treating cartilage injury, however there is no standard procedure for middle-aged patients who have diffuse knee osteoarthritis, especially of the lateral compartment. Therefore, Ochi developed a new distraction device that uses magnetic power to enlarge a joint space and promote cartilage regeneration with microfracture. The purpose of this study is to evaluate this new distraction arthroplasty system by using the cadaveric knee. Methods This study used ten knees from six cadavers that were embalmed by Thiel's methods. The medial and lateral joint space was measured by AP radiographic view before and after distraction, and after weight-bearing to evaluate the joint distraction. The contact pressure of the medial and lateral compartments at the knee extension position by using a prescale film system was measured before and after weight-bearing with a 15 or 30-kg weight-bearing load to evaluate the effectiveness of this device. Findings The lateral joint space significantly increased from the pre-distraction to the post-distraction; however, it did not change significantly between post-distraction and post-weight-bearing. With a 15 or 30-kg weight-bearing load, the contact pressure of the lateral compartment significantly decreased from the pre-distraction to the post-distraction. Interpretation The most important advantage of this device is that it maintains a continuous distraction tension and enables almost the full range of motion of the knee. We believe that joint distraction by using magnetic force can be a promising option for cartilage injury in middle-aged patients.

To identify the relationship between knee flexion angle and femoral tunnel length, as well as the exit points of guidewires, when using a far anteromedial portal technique for posterolateral femoral tunnel drilling in double-bundle anterior cruciate ligament reconstruction. Using the far anteromedial portal technique in 8 cadaveric knees, femoral tunnel drilling for the posterolateral bundle was performed at 3 knee flexion angles: 90°, 110° and 130°. We measured the femoral tunnel length and the distances from each guidewire to the closest relevant structures. The mean tunnel length at 90° knee flexion (25.8 ± 1.8 mm) was significantly shorter than the length at 110° and 130° knee flexion (32.1 ± 2.6 and 33.1 ± 2.5 mm, respectively). The average distance between the exit point of the guidewire and the posterior articular cartilage of the lateral femoral condyle was the shortest at 90° knee flexion (3.3 ± 2.2 mm). The distance between the guidewire and the centre of the origin of the lateral collateral ligament was the shortest at 130° knee flexion (8.0 ± 1.8 mm). The guidewires penetrated the origin of the lateral gastrocnemius tendon in 2 cases at 110° knee flexion and in 1 case each at 90° and 130° knee flexion. When using the far anteromedial portal technique, more than 110° knee flexion is desirable to achieve ideal femoral tunnel length and avoid articular cartilage injury. In addition, the risk of damage to the origin of the lateral collateral ligament increases when the knee flexion angle increases to 130°. A knee flexion angle between 110° and 120° was recommended when using the far anteromedial portal technique.

For the treatment of ununited fractures, we developed a system of delivering magnetic labelled mesenchymal stromal cells (MSCs) using an extracorporeal magnetic device. In this study, we transplanted ferucarbotran-labelled and luciferase-positive bone marrow-derived MSCs into a non-healing femoral fracture rat model in the presence of a magnetic field. The biological fate of the transplanted MSCs was observed using luciferase-based bioluminescence imaging and we found that the number of MSC derived photons increased from day one to day three and thereafter decreased over time. The magnetic cell delivery system induced the accumulation of photons at the fracture site, while also retaining higher photon intensity from day three to week four. Furthermore, radiological and histological findings suggested improved callus formation and endochondral ossification. We therefore believe that this delivery system may be a promising option for bone regeneration.

The purpose of this study is to clarify the kinetics of transplanted mesenchymal stem cells (MSCs) in rat skeletal muscle injury model and the contribution of the magnetic cell delivery system to muscle injury repair. A magnetic field generator was used to apply an external magnetic force to the injury site of the tibia anterior muscle, and 1 × 106 MSCs labeled with ferucarbotran–protamine complexes, which were isolated from luciferase transgenic rats, were injected into the injury site. MSCs were injected with and without an external magnetic force (MSC M+ and MSC M− groups, respectively), and phosphate-buffered saline was injected into injury sites as a control. In vivo bioluminescence imaging was performed immediately after the transplantation and, at 12, 24, and 72 h, and 1 and 4 weeks post-transplantation. Also, muscle regeneration and function were histologically and electromechanically evaluated. In vivo bioluminescence imaging showed that the photon of the MSC M+ group was significantly higher than that of the MSC M− group throughout the observation period. In addition, muscle regeneration and function in the MSC M+ group was histologically and functionally better than that of the MSC M− group. The results of our study indicated that magnetic cell delivery system may be of use in directing the transplanted MSCs to the injury site to promote skeletal muscle regeneration. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 754–759, 2013

Background Autologous chondrocyte implantation (ACI) is an important procedure when repairing cartilage defects of the knee. We previously reported several basic studies on tissue-engineered cartilage, and conducted a multicenter clinical study in 2009. In this clinical study, we evaluated the patients’ clinical scores and MRI findings before and after tissue-engineered cartilage implantation, and compared the data obtained at 1 year and approximately 6 years post-implantation. Methods Fourteen patients who underwent implantation of tissue-engineered cartilage to repair cartilage defects of the knee were evaluated. Tissue-engineered cartilage was produced by culturing autologous chondrocytes three dimensionally in atelocollagen gel. The patients were evaluated clinically using the Lysholm score, and the original knee-function score at pre-implantation and at 1 year and approximately 6 years post-implantation. MRI scans were obtained at the same observation periods. A modified magnetic resonance observation of cartilage repair tissue (MOCART) system was used to quantify clinical efficacy based on the MRI findings. Results In approximately 6 years of follow-up, none of the 14 patients reported any subjective symptoms of concern. The mean Lysholm score and the original knee-function score (63.0 ± 10.1, 59.9 ± 5.7) significantly improved at 1 year after implantation (86.4 ± 11.8, 94.1 ± 9.2), and were maintained until 6 years after implantation (89.8 ± 6.2, 89.9 ± 11.2), although some patients showed deterioration of Lysholm and original knee scores between 1 year post-implantation and the final follow-up. The mean MOCART score was 13.2 ± 12.0 pre-implantation, and 62.5 ± 24.7 at 1 year and 70.7 ± 22.7 at approximately 6 years post-implantation. The MOCART scores at 1 year and 6 years were significantly higher than the pre-implantation score, but there was no significant difference between the scores at 1 and 6 years, indicating that the MRI results at 1 year after implantation were maintained for the next 5 years. Conclusions The clinical scores and MRI findings after implantation of tissue-engineered cartilage were improved at 1 year after implantation and were maintained until 6 years after implantation.

There are various indirect signs of a discoid lateral meniscus in radiographs, for example lateral joint space widening, hypoplasia of the LFC, etc. There has, however, been no previous report of the characteristic shape of the lateral femoral condyle (LFC) in patients with osteochondritis dissecans (OCD) accompanied by a discoid lateral meniscus. The purpose of this study was to evaluate the characteristic shape of the LFC in patients with OCD accompanied by a discoid lateral meniscus, and sex differences associated with the shape of the LFC in those patients.This study included 29 males (31 knees) and 29 females (32 knees) of average age 17.7 years. There were 15 knees in 15 patients that were accompanied by OCD of the LFC (9 males, 9 knees; 6 females, 6 knees; average age 14.9 years; OCD group). There were 48 knees in 43 patients that were not accompanied by OCD of the LFC (20 males, 22 knees; 23 females, 26 knees; average age 17.6 years; non-OCD group). Standardized Rosenberg view radiographs of the knee were obtained for all patients. We evaluated the shape of LFC using the Rosenberg view and measured the condylar prominence ratio of the medial and lateral condyles adjacent to the intercondylar notch, in accordance with Ha's procedure.The OCD group had a significantly larger prominence ratio than the non-OCD group. The prominence ratio for males was significantly larger than that for females.We clearly demonstrated that the prominence ratio in the OCD group was significantly larger than that in the non-OCD group, indicating that the shape of the LFC and OCD in the LFC may be associated with the development of these lesions.

Purpose The purpose of this study was to determine the relation between the position of the transverse ligament, the anterior edge of the anterior cruciate ligament (ACL) tibial footprint, and the center of the ACL tibial insertion. We used arthroscopy for localization of the anatomic landmarks, followed by insertions of guide pins under direct visualization, and then the position of these guide pins was checked on plain lateral radiographs. Methods The transverse ligament and the anterior aspect of the ACL tibial footprint were identified by arthroscopy in 20 unpaired cadaveric knees (10 left and 10 right). Guide pins were inserted with tibial ACL adapter drill guides under direct observation at the transverse ligament, the anterior aspect of the tibial footprint, and the center of tibial insertion of the ACL. Then, plain lateral radiographs of specimens were taken. The Amis and Jakob line was used to define the attachment of the ACL tibial insertion and the transverse ligament. A sagittal percentage of the location of the insertion point was determined and calculated from the anterior margin of the tibia in the anteroposterior direction. Results The transverse ligament averaged 21.20% ± 4.1%, the anterior edge of the ACL tibial insertion averaged 21.60% ± 4.0%, and the center of the ACL tibial insertion averaged 40.30% ± 4.8%. There were similar percent variations between the transverse ligament and the anterior edge of the ACL tibial insertion, with no significant difference between them ( P = .38). Intraobserver and interobserver reliability was high, with small standard errors of measurement. Conclusions This study shows that the transverse ligament coincides with the anterior edge of the ACL tibial footprint in the sagittal plane. Clinical Relevance The transverse ligament can be considered as a new landmark for tibial tunnel positioning during anatomic ACL reconstruction.

Objective The purpose of this study was to evaluate cartilage defect at medial femoral condyle on MRI in early osteoarthritis and to compare with early osteoarthritis with meniscal tear without clear cartilage defect. Materials and Methods Twelve patients with medial pain of the knee and cartilage defect without meniscal tear by MRI were studied for cartilage defect. There were two males and 10 females with cartilage defect, and they were between 42 and 61 years of age (average, 51.6). Fifteen patients with medial pain of the knee and meniscal tear and without clear cartilage defect had been studied as meniscal tear cases. There were five males and 10 females with meniscal tear, and they were between 45 and 61 years of age (average 54.5). In both groups, knee injuries by trauma and Kellgren radiographic grade III and IV osteoarthritis were excluded. We compared cartilage defect cases and meniscal tear cases by gender, age, medial meniscus displacement ratio from the edge of the tibial medial joint surface, femorotibial angle (FTA) and Mikulicz line. We measured medial meniscus displacement ratio by the proportion of medial meniscus lesion protruding from the edge of tibial medial joint surface to all the medial meniscus width on MRI. For the evaluation of Mikulicz line, we measured the score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width. χ 2 Test was used for gender, and Mann–Whitney U test was used for age, medial meniscus displacement ratio, FTA and Mikulicz line. Results Statistically significant difference was not observed between cartilage defect cases and meniscal tear cases for age and gender. Medial meniscus displacement ratio was 13±12.3% in cartilage defect cases and 50.4±20.1% in meniscal tear cases. Medial meniscus displacement ratio in cartilage defect cases was significantly smaller than in meniscal tear cases ( P =.0001). FTA was 174.9±2.2° in cartilage defect cases and 178.3±4.8° in meniscal tear cases. FTA in cartilage defect cases was significantly smaller than in meniscal tear cases ( P =.00390). The score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width was 35.8±11.8% in cartilage defect cases and 21.7±15.8% in meniscal tear cases. Mikulicz line in cartilage defect cases passes more laterally than in meniscal tear cases significantly ( P =.0264). Conclusion In this study, we reported cartilage defect cases at medial femoral condyle in the early osteoarthritis of the knee. We think that these cases were different from early osteoarthritis with meniscal tear in alignment of lower limb and onset mechanism. It is necessary to evaluate meniscus and cartilage in MRI when we diagnose middle-aged patients with medial pain of the knee and without remarkable changes of X-ray.

Purpose In revision anterior cruciate ligament reconstruction (ACLR), the single-stage technique and the over-the-top route (OTTR) procedure were usually selected for cases where the bone tunnel cannot be created at an anatomical position due to tunnel enlargement and overlap with the mal-positioned tunnel of primary reconstruction. The purpose of this study was to evaluate the clinical results of revision single-bundle ACL reconstruction using OTTR procedure and to compare the clinical results of OTTR procedure with those of anatomical single bundle revision reconstruction (SBR). Hypothesis The results of OTTR procedure are equivalent to that of SBR. Methods Seventy-six revision ACL reconstruction knees from April 2002 to December 2012 were involved in our study. We focused on 21 knees which underwent surgery with SBR and 22 knees with OTTR using hamstring tendon. The clinical results were evaluated by means of the Lysholm score and the knee stability was assessed by the Lachman test, pivot-shift test and side-to-side difference by KT-2000 preoperatively and after 1 year postoperatively. AP translation and rotational laxity using a navigation system were evaluated before and after revision ACL reconstruction under anesthesia in 8 cases of OTTR and in 6 cases of SBR. Results There was no statistically significant difference between the OTTR and SBR regarding Lysholm score, Lachman test, pivot-shift test, ATT by KT-2000, and AP translation and rotational laxity with a navigation system. Conclusions The clinical results of OTTR are almost equivalent to those of SBR. For the cases in which it is impossible to create the femoral tunnel in an anatomical position, OTTR is a valuable revision ACL reconstruction method. Level of evidence Case-control study Level III.

Summary Introduction Assessment of soft-tissue balance by the gap technique in Total Knee Arthroplasty (TKA) impacts femoral component rotation positioning. Proper femoral component rotation is a critical factor in TKA, both for adequate patellar tracking and in achieving a symmetrical flexion gap. Soft tissue balance assessment and gap measurements are performed at 90° flexion and with the patella everted in conventional TKA; during MIS-TKA, this step is performed with the patella in situ. We therefore investigated intra-operative joint gap parameters at 90° flexion with and without patellar eversion during conventional TKA, so as to better understand the influence of this intraoperative patellar position factor on final ligament balance. Hypothesis Conducting TKA without patellar eversion increases both gap size and gap inclination. Materials and methods Twenty-four osteoarthritic knees were included in the study. Joint gap size and inclination were measured intraoperatively on a knee in 90° flexion, with and without patellar eversion. Results The joint gap with patella in situ (17.0 ± 3.4 mm) was significantly greater than with patellar eversion (15.4 ± 3.0 mm), as was gap inclination at 90° flexion with the patella in situ (4.9 ± 3.1°) compared to with patellar eversion (4.0 ± 2.9°). Discussion The flexion gap inclination obtained without patellar eversion was steeper than with patellar eversion. This induced more externally rotated femoral positioning in absence of patellar eversion. These results ought to be taken into account by surgeons considering switching from conventional to MIS-TKA. Level of evidence Level II. Prospective randomized study.

Far antero-medial (FAM) portal technique is usually used in our department in anterior cruciate ligament (ACL) reconstruction when drilling the femoral tunnel. Although the FAM portal technique carrries potential risks, such as cartilage injury of the lateral femoral condyle, peroneal nerve injury and blow out of the lateral femoral condyle's posterior wall, these problems were resolved in a cadaveric study, in which 110°–120° knee flexion was recommended when drilling the femoral tunnel. However, there is a potential risk of injuring the cartilage of the medial femoral condyle especially when drilling the postero-lateral bundle. A new method is proposed to ensure that the femoral tunnel drilling does not damage the cartilage of the medial femoral condyle.