Repetitive allogeneic intraarticular injections of synovial mesenchymal stem cells promote meniscus regeneration in a porcine massive meniscus defect model

OBJECTIVE

A new strategy is required in order to regenerate a meniscus for extensive defects. Synovial mesenchymal stem cells (MSCs) are an attractive cell source for meniscus regeneration due to their high proliferation and chondrogenic potential. We examined the effect of repetitive intraarticular injections of synovial MSCs on meniscus regeneration in a massive meniscal defect of pigs. We followed up the efficacy using MRI evaluation in addition to macroscopic and histological observations.

DESIGN

Two weeks before the injection of synovial MSCs, the anterior half of the medial menisci was resected in both knees of pigs. Fifty million allogeneic synovial MSCs were injected into the right knee at 0, 2, and 4 weeks and followed up by sequential MRI. The regenerated meniscus, adjacent articular cartilage, and subchondral bone were evaluated by MRI at 2, 4, 8, 12 and 16 weeks. They were also evaluated macroscopically and histologically at 16 weeks (n = 7).

RESULTS

The resected meniscus regenerated significantly better in the MSC group than in the control group based on histological and MRI analyses. Macroscopically, the meniscal defect already appeared to be filled with synovial tissue at 2 weeks. Articular cartilage and subchondral bone at the medial femoral condyle were also significantly more preserved in the MSC group based on MRI, macroscopic, and histological analyses.

CONCLUSIONS

Intraarticular injections of allogeneic synovial MSCs appeared to promote meniscus regeneration and provide protection at the medial femoral articular cartilage in a porcine massive meniscal defect model.

Mesenchymal stem cells in synovial fluid increase after meniscus injury

BACKGROUND

Although relatively uncommon, spontaneous healing from a meniscus injury has been observed even within the avascular area. This may be the result of the existence of mesenchymal stem cells in synovial fluid.

QUESTIONS/PURPOSES

The purpose of this study was to investigate whether mesenchymal stem cells existed in the synovial fluid of the knee after meniscus injury.

METHODS

Synovial fluid was obtained from the knees of 22 patients with meniscus injury just before meniscus surgery and from 8 volunteers who had no history of knee injury. The cellular fraction of the synovial fluid was cultured for 14 days followed by analysis for multilineage potential and presentation of surface antigens characteristic of mesenchymal stem cells. Colony-forming efficiency and proliferation potential were also compared between the two groups.

RESULTS

Cells with characteristics of mesenchymal stem cells were observed in the synovial fluid of injured knees to a much greater degree than in uninjured knees. The colony-forming cells derived from the synovial fluid of the knee with meniscus injury had multipotentiality and surface epitopes identical to mesenchymal stem cells. The average number of colony formation, obtained from 1 mL of synovial fluid, in meniscus-injured knees was 250, higher than that from healthy volunteers, which was 0.5 (p < 0.001). Total colony number per synovial fluid volume was positively correlated with the postinjury period (r = 0.77, p < 0.001).

CONCLUSIONS

Mesenchymal stem cells were found to exist in synovial fluid from knees after meniscus injury. Mesenchymal stem cells were present in higher numbers in synovial fluid with meniscus injury than in normal knees. Total colony number per synovial fluid volume was positively correlated with the postinjury period.

CLINICAL RELEVANCE

Our current human study and previous animal studies suggest the possibility that mesenchymal stem cells in synovial fluid increase after meniscus injury contributing to spontaneous meniscus healing.

Anatomic and histologic analysis of the mid-substance and fan-like extension fibres of the anterior cruciate ligament during knee motion, with special reference to the femoral attachment

PURPOSE

The purpose of this study is to evaluate the morphology of the mid-substance and fan-like extension fibres of ACL during knee motion with reference to the femoral attachment.

METHODS

This study used six fresh-frozen cadaveric knees and 22 embalmed cadaveric knees to macroscopically evaluate morphological changes in the ACL attachment during knee motion. Three embalmed specimens fixed at knee extension and another three specimens fixed at 120° flexion were used for histologic observations.

RESULTS

The fan-like extension fibres were adhered to the bone surface and the fibre location and orientation in relation to the femoral surface did not change, regardless of the knee flexion angle, while the orientation of the mid-substance fibres in relation to the femur did change during knee motion. During knee flexion, a fold in the ACL femoral attachment was observed at the border between the mid-substance and the fan-like extension fibres. The attachment of the mid-substance fibres was significantly smaller than the attachment of the fan-like extension fibres.

CONCLUSION

The present study clarified anatomic and histologic character of the mid-substance fibres and fan-like extension fibres, and provided critical information for future clinical and biomechanical studies concerning both two different fibres. Specifically for ACL reconstruction, it is difficult to reconstruct the natural fan-like extension fibres by creating a tunnel at the femoral and tibial ends of each fibre bundle, although the mid-substance fibres can be reconstructed by such procedures.

Transplantation of Achilles tendon treated with bone morphogenetic protein 7 promotes meniscus regeneration in a rat model of massive meniscal defect

Objective

This study was undertaken to examine whether bone morphogenetic protein 7 (BMP-7) induces ectopic cartilage formation in the rat tendon, and whether transplantation of tendon treated with BMP-7 promotes meniscal regeneration. Additionally, we analyzed the relative contributions of host and donor cells on the healing process after tendon transplantation in a rat model.

Methods

BMP-7 was injected in situ into the Achilles tendon of rats, and the histologic findings and gene profile were evaluated. Achilles tendon injected with 1 μg of BMP-7 was transplanted into a meniscal defect in rats. The regenerated meniscus and articular cartilage were evaluated at 4, 8, and 12 weeks. Achilles tendon from LacZ-transgenic rats was transplanted into the meniscal defect in wild-type rats, and vice versa.

Results

Injection of BMP-7 into the rat Achilles tendon induced the fibrochondrocyte differentiation of tendon cells and changed the collagen gene profile of tendon tissue to more closely approximate meniscal tissue. Transplantation of the rat Achilles tendon into a meniscal defect increased meniscal size. The rats that received the tendon treated with BMP-7 had a meniscus matrix that exhibited increased Safranin O and type II collagen staining, and showed a delay in articular cartilage degradation. Using LacZ-transgenic rats, we determined that the regeneration of the meniscus resulted from contribution from both donor and host cells.

Conclusion

Our findings indicate that BMP-7 induces ectopic cartilage formation in rat tendons. Transplantation of Achilles tendon treated with BMP-7 promotes meniscus regeneration and prevents cartilage degeneration in a rat model of massive meniscal defect. Native cells in the rat Achilles tendon contribute to meniscal regeneration.

[Articular cartilage regenerative therapy with synovial mesenchymal stem cells in a pig model]

Current therapies for cartilage injury remain some issues such as the quality of regenerated cartilage and its invasiveness. We have been trying to develop a low invasive treatment for cartilage regeneration with synovial mesenchymal stem cells (MSCs) . Here we introduce our preclinical study with miniature pigs whose knee joints are similar to those of humans in terms of size and cartilage metabolism. Cartilage defect was created at the weight bearing area of both porcine knee joints. Synovial MSCs were transplanted by delivering a synovial MSC suspension onto the cartilage defect of the one side and the knee was kept immobilized for 10 minutes. Sequential arthroscopic and histological observations showed the contribution of synovial MSCs after transplantation, and a better hyaline cartilaginous-tissue regeneration in the MSC-treated knees than in the non-treated control knees at 12 weeks. Based on this and other preclinical studies, we have started a clinical study for cartilage regeneration with autologous synovial MSCs.

Intraarticular injection of synovial stem cells promotes meniscal regeneration in a rabbit massive meniscal defect model

We investigated whether single intraarticular injection of synovial MSCs enhanced meniscal regeneration in a rabbit massive meniscal defect model. Synovium were harvested from the knee joint of rabbits, and the colony-forming cells were collected. Two weeks after the anterior half of the medial menisci were excised in both knees, 1 × 10(7) MSCs in 100 μl PBS were injected into the right knee. The MSC and control groups were compared macroscopically and histologically at 1, 3, 4, and 6 months (n = 4). Articular cartilage of the medial femoral condyle was also evaluated histologically at 6 months. Multipotentiality of the colony-forming cells was confirmed. Injected MSCs labeled with DiI were detected and remained in the meniscal defect at 14 days. The size of meniscus in the MSC group was larger than that in the control group at 1 and 3 months. The difference of the size between the two groups was indistinct at 4 and 6 months. However, histological score was better in the MSC group than in the control group at 1, 3, 4, and 6 months. Macroscopically, the surface of the medial femoral condyle in the control group was fibrillated at 6 months, while looked close to intact in the MSC group. Histologically, defect or thinning of the articular cartilage with sclerosis of the subchondral bone was observed in the control group, contrarily articular cartilage and subchondral bone were better preserved in the MSC group. Synovial MSCs injected into the knee adhered around the meniscal defect, and promoted meniscal regeneration in rabbits.

Transplantation of aggregates of synovial mesenchymal stem cells regenerates meniscus more effectively in a rat massive meniscal defect

Transplantation of mesenchymal stem cells (MSCs) derived from synovium is a possible therapy for meniscus regeneration. We have previously reported that intraarticular injection of 5 million synovial MSCs promoted meniscal regeneration in rat meniscal defects. However, if a similar cell number per body weight were required, preparation of required human MSCs would not be practical in a clinical situation. The use of aggregates of MSCs may be one of the solutions. Here, we investigated whether the use of aggregates of synovial MSCs regenerated meniscus more effectively in a rat meniscectomized model. The total number of synovial MSCs was adjusted to 25,000 cells, and aggregates consisting of MSCs or 25,000 MSCs suspended in PBS were placed on the meniscal defects. Five million MSCs suspended in PBS were also used as another control. For the regenerated menisci, the area was larger and the histological findings were closer to that of the normal meniscus in the aggregate groups than to that in the suspension groups at 4 weeks. The effects of transplantation of aggregates were still observed at 12 weeks. Luminescence intensity remained higher at 3 weeks and thereafter in the aggregate group than in the suspension group when the same number of luciferase expressing MSCs were transplanted. We confirmed that MSCs transplanted as aggregates existed in the regenerated meniscus focally and partially. Transplantation of aggregates of synovial MSCs regenerated meniscus more effectively in a rat massive meniscal defect.

Intraoperative joint gaps affect postoperative range of motion in TKAs with posterior-stabilized prostheses

BACKGROUND

Joint gaps and mediolateral (ML) soft tissue balance have long been known to affect clinical scores and patient function after TKA, but the relationship between gaps and soft tissue balance remain poorly defined. If specific relationships exist between soft tissue tension and patient function, then objective targets could be established to assist surgeons in achieving more consistent postoperative knee function.

QUESTIONS/PURPOSES

By performing instrumented gap measurements during TKA, we sought to quantify the relationships between intraoperative soft tissue tension and clinical scores and patient function.

METHODS

We prospectively followed 57 patients with 63 primary TKAs with posterior-stabilized prostheses. Joint gaps and ML soft tissue balance were measured intraoperatively from 0° to 135° with the patella reduced after independent bone cuts and soft tissue releases. We determined the relationships between these intraoperative measurements and postoperative ROM and Knee Society scores at minimum 2-year followup.

RESULTS

Larger joint gaps at 120° and 135° flexion predicted larger postoperative knee flexion (r=0.296 and r=0.393, respectively), whereas larger gaps at 10° flexion predicted greater postoperative knee extension (r=0.285). Knees with rectangular joint gaps did not show better ROM or Knee Society scores compared with knees with trapezoidal joint gaps. In the range of normal surgical variation, neither joint gaps nor gap asymmetry affected the incidence of postoperative instability.

CONCLUSIONS

Avoiding small joint gaps in extension and in deep flexion should allow patients who undergo TKAs to obtain maximum ROM.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Incidence and risk factors for medial tibial stress syndrome and tibial stress fracture in high school runners

PURPOSE

Medial tibial stress syndrome (MTSS) and tibial stress fracture (SF) are common lower leg disorders in runners. A prospective study was done to identify the incidence of MTSS and SF in high school runners and to determine risk factors.

METHODS

A total of 230 runners participating in high school running teams were evaluated. All runners aged 15 years as first grade of high school were involved in the study. They were followed up for 3 years. The measured items included height, weight, body mass index (BMI), range of hip and ankle motion, straight leg raising (SLR), intercondylar and intermalleolar interval, Q-angle, navicular drop test, hip abductor strength and physical conditioning. Each runner was followed for 3 years to report occurrence of MTSS and SF.

RESULTS

A total number of 102 MTSS (0.29 athlete exposures) and 21 SF (0.06 athlete exposures) were identified. In females, BMI significantly increased the risk of MTSS after adjustment for the other variables in this study (adjusted odds ratio, 0.51; 95 % confidence interval, 0.31-0.86). Increased internal rotation of the hip significantly increased the risk of MTSS (adjusted odds ratio, 0.91; 95 % confidence interval, 0.85-0.99). In males, limited SLR also significantly increased the risk of SF with adjustment for the other variables in this study (adjusted odds ratio, 1.38; 95 % confidence interval, 1.04-1.83).

CONCLUSION

A significant relationship was found between BMI, internal hip rotation angle and MTSS in females, and between limited SLR and SF in males.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

The kinematic analysis of female subjects after double-bundle anterior cruciate ligament reconstruction during single-leg squatting

BACKGROUND

The kinematic characteristics of female anterior cruciate ligament (ACL)-injured subjects were recognized in our previous study using an electromagnetic device comparing both female control groups and male ACL-injured subjects during single-leg squatting.

OBJECTIVE

To assess the kinematic characteristics of female subjects after double-bundle ACL reconstruction during single-leg squatting.

METHODS

Three-dimensional motion analysis was performed for single-leg squatting in female subjects after ACL reconstruction. We evaluated the relative angles between the pelvis, thigh, and lower leg using an electromagnetic device during single-leg squatting in 28 female subjects with ACL reconstruction. All patients included in this study restored their sports performance level to 90 % or higher.

RESULTS

Comparing the involved leg to the uninjured leg of female subjects after ACL reconstruction, the involved leg demonstrated significantly more hip adduction and less knee varus than the uninjured leg. Comparing the anterior cruciate ligament-reconstructed female subjects to the healthy female controls, the involved leg after ACL reconstruction demonstrated significantly less hip flexion, more hip external rotation, more hip adduction, and more knee flexion than the dominant leg of the control group.

CONCLUSION

This kinematic study exhibited kinematic characteristics of ACL-reconstructed knees of female subjects. Double-bundle anterior cruciate ligament reconstruction could not quite restore the normal kinematics of female-involved legs compared with both uninjured legs of female subjects and healthy female controls. In future studies, restoring the correct alignment of ACL reconstructed knee during single-leg squatting would be expected to reduce ACL re-injury and to assist a safe return to sport activities.

Effect of posterolateral bundle graft fixation angles on graft tension curves and load sharing in double-bundle anterior cruciate ligament reconstruction using a transtibial drilling technique

PURPOSE

To evaluate the effect of posterolateral bundle (PLB) graft fixation angles on graft tension curves and load sharing between the anteromedial bundle (AMB) and the PLB in double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-four patients who underwent double-bundle ACL reconstruction were included in this study. AMB and PLB were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion-extension and in response to anterior or rotatory loads. A pivot-shift test, as well as factors affecting the residual pivot-shift, was also evaluated.

RESULTS

A20P45 created reciprocal tension curves and load sharing, in which the tension in both bundles was equivalent during flexion-extension and during each loading test at 30°. In A20P0, the tension of the AMB was constantly higher than that of the PLB. Seven patients showed grade 1 pivot-shift phenomenon in A20P0, whereas no patient showed a positive pivot-shift at other settings. Larger tension reduction of the PLB between 0° and 30° and smaller load sharing of the PLB were significant factors affecting residual pivot-shift.

CONCLUSIONS

In double-bundle ACL reconstruction, fixation of the AMB at 20° and the PLB at 45° created reciprocal tension curves and load sharing between the bundles. Fixation of the AMB at 20° and the PLB at 0° led to insufficient tension in the PLB, resulting in a residual pivot-shift phenomenon in 7 of 24 patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Human YKL39 (chitinase 3-like protein 2), an osteoarthritis-associated gene, enhances proliferation and type II collagen expression in ATDC5 cells

Human YKL39 (chitinase 3-like protein 2/CHI3L2) is a secreted 39kDa protein produced by articular chondrocytes and synoviocytes. Recent studies showed that hYKL-39 expression is increased in osteoarthritic articular chondrocytes suggesting the involvement of hYKL-39 in the progression of osteoarthritis (OA). However little is known regarding the molecular function of hYKL-39 in joint homeostasis. Sequence analyses indicated that hYKL-39 has significant identity with the human chitotorisidase family molecules, although it is considered that hYKL-39 has no enzymatic activity since it lacks putative chitinase catalytic motif. In this study, to examine the molecular function of hYKL-39 in chondrocytes, we overexpressed hYKL-39 in ATDC5 cells. Here we report that hYKL-39 enhances colony forming activity, cell proliferation, and type II collagen expression in these cells. These data suggest that hYKL-39 is a novel growth and differentiation factor involved in cartilage homeostasis.

Osteopontin level in synovial fluid is associated with the severity of joint pain and cartilage degradation after anterior cruciate ligament rupture

Objective

To explore the molecular function of Osteopontin (OPN) in the pathogenesis of human OA, we compared the expression levels of OPN in synovial fluid with clinical parameters such as arthroscopic observation of cartilage damage and joint pain after joint injury.

Methods

Synovial fluid was obtained from patients who underwent anterior cruciate ligament (ACL) reconstruction surgery from 2009 through 2011 in our university hospital. The amounts of intact OPN (OPN Full) and it’s N-terminal fragment (OPN N-half) in synovial fluid from each patient were quantified by ELISA and compared with clinical parameters such as severity of articular cartilage damage (TMDU cartilage score) and severity of joint pain (Visual Analogue Scale and Lysholm score).

Results

Within a month after ACL rupture, both OPN Full and N-half levels in patient synovial fluid were positively correlated with the severity of joint pain. In contrast, patients with ACL injuries greater than one month ago felt less pain if they had higher amounts of OPN N-half in synovial fluid. OPN Full levels were positively correlated with articular cartilage damage in lateral tibial plateau.

Conclusion

Our data suggest that OPN Full and N-half have distinct functions in articular cartilage homeostasis and in human joint pain.

Arthroscopic centralization of an extruded lateral meniscus

Extrusion of the lateral meniscus has been reported after posterior root tear or radial tear, partial meniscectomy, and meniscoplasty of discoid meniscus. It has also been shown to be associated with the development of osteoarthritis. This technical note describes a new arthroscopic technique to centralize and stabilize the mid body of the lateral meniscus to restore and maintain the lateral meniscus function by repairing/preventing extrusion of the meniscus. A JuggerKnot Soft Anchor (Biomet, Warsaw, IN), loaded with a MaxBraid suture (Biomet), was placed on the lateral edge of the lateral tibial plateau, just anterior to the popliteal hiatus, through a midlateral portal. A Micro Suture Lasso Small Curve with Nitinol Wire Loop (Arthrex, Naples, FL) was used to pass 2 limbs of the MaxBraid suture through the meniscus at the margin between the meniscus and the capsule. Another anchor was inserted on the lateral edge of the lateral tibial plateau, 1 cm anterior to the first anchor, and the same procedure was repeated. The sutures were then tied by use of a self-locking sliding knot, achieving centralization and secure stabilization of the lateral meniscus.

Intra-articular injection of human mesenchymal stem cells (MSCs) promote rat meniscal regeneration by being activated to express Indian hedgehog that enhances expression of type II collagen

OBJECTIVE

Meniscal regeneration was previously shown to be enhanced by injection of mesenchymal stem/stromal cells (MSCs) but the mode of action of the MSCs was not established. The aim of this study was to define how injection of MSCs enhances meniscal regeneration.

DESIGN

A hemi-meniscectomy model in rats was used. Rat-MSCs (rMSCs) or human-MSCs (hMSCs) were injected into the right knee joint after the surgery, and PBS was injected into the left. The groups were compared macroscopically and histologically at 2, 4, and 8 weeks. The changes in transcription in both human and rat genes were assayed by species-specific microarrays and real-time RT-PCRs.

RESULTS

Although the number of hMSCs decreased with time, hMSCs enhanced meniscal regeneration in a manner similar to rMSCs. hMSCs injection increased expression of rat type II collagen (rat-Col II), and inhibited osteoarthritis progression. The small fraction of hMSCs was activated to express high levels of a series of genes including Indian hedgehog (Ihh), parathyroid hormone-like hormone (PTHLH), and bone morphogenetic protein 2 (BMP2). The presence of hMSCs triggered the subsequent expression of rat-Col II. An antagonist of hedgehog signaling inhibited the expression of rat-Col II and an agonist increased expression of rat-Col II in the absence of hMSCs.

CONCLUSIONS

Despite rapid reduction in cell numbers, intra-articular injected hMSCs were activated to express Ihh, PTHLH, and BMP2 and contributed to meniscal regeneration. The hedgehog signaling was essential in enhancing the expression of rat-Col II, but several other factors provided by the hMSCs probably contributed to the repair.

Isolation and characterization of multipotential mesenchymal cells from the mouse synovium

The human synovium contains mesenchymal stem cells (MSCs), which are multipotential non-hematopoietic progenitor cells that can differentiate into a variety of mesenchymal lineages and they may therefore be a candidate cell source for tissue repair. However, the molecular mechanisms by which this can occur are still largely unknown. Mouse primary cell culture enables us to investigate the molecular mechanisms underlying various phenomena because it allows for relatively easy gene manipulation, which is indispensable for the molecular analysis. However, mouse synovial mesenchymal cells (SMCs) have not been established, although rabbit, cow, and rat SMCs are available, in addition to human MSCs. The aim of this study was to establish methods to harvest the synovium and to isolate and culture primary SMCs from mice. As the mouse SMCs were not able to be harvested and isolated using the same protocol for human, rat and rabbit SMCs, the protocol for humans was modified for SMCs from the Balb/c mouse knee joint. The mouse SMCs obtained showed superior proliferative potential, growth kinetics and colony formation compared to cells derived from muscle and bone marrow. They expressed PDGFRá and Sca-1 detected by flow cytometry, and showed an osteogenic, adipogenic and chondrogenic potential similar or superior to the cells derived from muscle and bone marrow by demonstrating in vitro osteogenesis, adipogenesis and chondrogenesis. In conclusion, we established a primary mouse synovial cell culture method. The cells derived from the mouse synovium demonstrated both the ability to proliferate and multipotentiality similar or superior to the cells derived from muscle and bone marrow.

Comparison of Gingiva, Dental Pulp, and Periodontal Ligament Cells From the Standpoint of Mesenchymal Stem Cell Properties

The specific properties of mesenchymal stem cells (MSCs) in oral tissues still remain unknown though their existence has been previously reported. We collected gingiva, dental pulp, and periodontal ligament tissues from removed teeth and isolated MSCs. These MSCs were compared in terms of their yields per tooth, surface epitopes, and differentiation potentials by patient-matched analysis. For in vivo calcification analysis, rat gingival and dental pulp cells mounted on β-tricalcium phospateTCP were transplanted into the perivertebral muscle of rats for 6 weeks. Gingival cells and dental pulp cells showed higher yield per tooth than periodontal ligament cells (n=6, p<0.05). Yields of periodontal ligament cells were too low for further analysis. Gingival and dental pulp cells expressed MSC markers such as CD44, CD90, and CD166. Gingival and dental pulp cells obtained phenotypes of chondrocytes and adipocytes in vitro. Approximately 60% of the colonies of gingival cells and 40% of the colonies of dental pulp cells were positively stained with alizarin red in vitro, and both gingival and dental pulp cells were calcified in vivo. We clarified properties of MSCs derived from removed teeth. We could obtain a high yield of MSCs with osteogenic potential from gingiva and dental pulp. These results indicate that gingiva and dental pulp are putative cell sources for hard tissue regeneration.

Hyaluronan injection therapy for athletic patients with patellar tendinopathy

BACKGROUND

Patellar tendinopathy produces activity-related pain and focal tenderness at the attachment of the patellar tendon at the lower pole of the patella. It frequently causes a reduction in athletic ability. An injection of hyaluronan was found to be useful for patellar tendinopathy, provided the indication is appropriate, based on the authors' pilot cases. The purpose of this study was to summarize the clinical experience of and to describe the appropriate indication for this injection therapy.

METHODS

Fifty patients were treated from January 1999 to December 2006. The observation period averaged 25.7 months (range 6-88). All patients were graded stage 2 or 3 by Blazina's classification. Each treatment was counted separately for 9 patients (10 knees) who had more than one treatment period with 3 months or more between the injections. There were 4 bilaterally injected patients. Patellar tendinopathy was classified into 4 types according to the degree of tenderness and the regions that are tender. Hyaluronan was injected into the interface between the patellar tendon and the infrapatellar fat pad at the proximal insertion, or into the region of maximum tenderness.

RESULTS

The total number of injections was 135, and there were an average of 2.0 injections per case (range 1-11). Following treatment, 54 % of the cases were rated in excellent condition, as they were able to return to their previous athletic activities with little difficulty, while 40 % of the cases were rated in good condition-these patients were able to return to their previous sporting activities with some degree of limitation.

CONCLUSIONS

Hyaluronan injection therapy for athletic patients with patellar tendinopathy is an optional but effective treatment.

Properties and usefulness of aggregates of synovial mesenchymal stem cells as a source for cartilage regeneration

INTRODUCTION

Transplantation of mesenchymal stem cells (MSCs) derived from synovium is a promising therapy for cartilage regeneration. For clinical application, improvement of handling operation, enhancement of chondrogenic potential, and increase of MSCs adhesion efficiency are needed to achieve a more successful cartilage regeneration with a limited number of MSCs without scaffold. The use of aggregated MSCs may be one of the solutions. Here, we investigated the handling, properties and effectiveness of aggregated MSCs for cartilage regeneration.

METHODS

Human and rabbit synovial MSCs were aggregated using the hanging drop technique. The gene expression changes after aggregation of synovial MSCs were analyzed by microarray and real time RT-PCR analyses. In vitro and in vivo chondrogenic potential of aggregates of synovial MSCs was examined.

RESULTS

Aggregates of MSCs cultured for three days became visible, approximately 1 mm in diameter and solid and durable by manipulation; most of the cells were viable. Microarray analysis revealed up-regulation of chondrogenesis-related, anti-inflammatory and anti-apoptotic genes in aggregates of MSCs. In vitro studies showed higher amounts of cartilage matrix synthesis in pellets derived from aggregates of MSCs compared to pellets derived from MSCs cultured in a monolayer. In in vivo studies in rabbits, aggregates of MSCs could adhere promptly on the osteochondral defects by surface tension, and stay without any loss. Transplantation of aggregates of MSCs at relatively low density achieved successful cartilage regeneration. Contrary to our expectation, transplantation of aggregates of MSCs at high density failed to regenerate cartilage due to cell death and nutrient deprivation of aggregates of MSCs.

CONCLUSIONS

Aggregated synovial MSCs were a useful source for cartilage regeneration considering such factors as easy preparation, higher chondrogenic potential and efficient attachment.

Human mesenchymal stem cells in synovial fluid increase in the knee with degenerated cartilage and osteoarthritis

We investigated whether mesenchymal stem cells (MSCs) in synovial fluid (SF) increased in the knee with degenerated cartilage and osteoarthritis. SF was obtained from the knee joints of 22 patients with anterior cruciate ligament (ACL) injury during ACL reconstruction, and cartilage degeneration was evaluated arthroscopically. SF was also obtained from the knee joints of 6 healthy volunteers, 20 patients with mild osteoarthritis, and 26 patients with severe osteoarthritis, in which the grading was evaluated radiographically. The cell component in the SF was cultured for analyses. Synovium (SYN) and bone marrow (BM) were also harvested during total knee arthroplasties. The MSC number in SF was correlated with the cartilage degeneration score evaluated by arthroscopy. The MSC number in the SF was hardly noticed in normal volunteers, but it increased in accordance with the grading of osteoarthritis. Though no significant differences were observed regarding surface epitopes, or differentiation potentials, the morphology and gene profiles in SF MSCs were more similar to those in SYN MSCs than in BM MSCs. We listed 20 genes which were expressed higher in both SYN MSCs and SF MSCs than in BM MSCs, and 3 genes were confirmed by quantitative RT-PCR. MSCs in SF increased along with degenerated cartilage and osteoarthritis.

[Locomotive syndrome and frailty. Total knee arthroplasty supports active life of the elderly]

For a society with an aging population, it is important to extend healthy life expectancy. Knee arthroplasty is one of the most successful and beneficial treatments for osteoarthritic knees, helping the elderly improve their activities of daily life. Previous reports have proved health-related quality of life improves dramatically with this surgery. In particular, pain and physical functioning scores improve significantly. Although the preoperative physical activity of each patient does affect the postoperative activity level, sufficient improvements can be expected for this procedure on the elderly. These effective improvements make the number of knee arthroplasties increase year to year. The elderly have high risks of postoperative medical complications. However, long term results are comparable or superior to those in younger patients. In elderly patients, pre-existing conditions should be carefully controlled, and postoperative complications, including infection and thrombosis, should be treated prophylactically to promote safety and postoperative recovery.

Arthroscopic, histological and MRI analyses of cartilage repair after a minimally invasive method of transplantation of allogeneic synovial mesenchymal stromal cells into cartilage defects in pigs

BACKGROUND AIMS

Transplantation of synovial mesenchymal stromal cells (MSCs) may induce repair of cartilage defects. We transplanted synovial MSCs into cartilage defects using a simple method and investigated its usefulness and repair process in a pig model.

METHODS

The chondrogenic potential of the porcine MSCs was compared in vitro. Cartilage defects were created in both knees of seven pigs, and divided into MSCs treated and non-treated control knees. Synovial MSCs were injected into the defect, and the knee was kept immobilized for 10 min before wound closure. To visualize the actual delivery and adhesion of the cells, fluorescence-labeled synovial MSCs from transgenic green fluorescent protein (GFP) pig were injected into the defect in a subgroup of two pigs. In these two animals, the wounds were closed before MSCs were injected and observed for 10 min under arthroscopic control. The defects were analyzed sequentially arthroscopically, histologically and by magnetic resonance imaging (MRI) for 3 months.

RESULTS

Synovial MSCs had a higher chondrogenic potential in vitro than the other MSCs examined. Arthroscopic observations showed adhesion of synovial MSCs and membrane formation on the cartilage defects before cartilage repair. Quantification analyses for arthroscopy, histology and MRI revealed a better outcome in the MSC-treated knees than in the non-treated control knees.

CONCLUSIONS

Leaving a synovial MSC suspension in cartilage defects for 10 min made it possible for cells to adhere in the defect in a porcine cartilage defect model. The cartilage defect was first covered with membrane, then the cartilage matrix emerged after transplantation of synovial MSCs.

The effect of graft fixation angles on anteroposterior and rotational knee laxity in double-bundle anterior cruciate ligament reconstruction: evaluation using computerized navigation

BACKGROUND

One of the main differences affecting outcome between single-bundle and double-bundle anterior cruciate ligament (ACL) reconstructions may be graft fixation angles and initial force settings; however, there has been little research to investigate these effects in either technique.

HYPOTHESIS

Anteroposterior and rotational knee laxities will be less in double-bundle ACL reconstructions than single-bundle reconstructions, and different graft fixation angles affect knee kinematics and pivot-shift phenomenon in double-bundle ACL reconstructions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven patients who underwent double-bundle ACL reconstruction were included in this study. The anteromedial bundle (AMB) and the posterolateral bundle (PLB) were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB only at 20° (A20), (2) PLB only at 20° (P20), (3) AMB at 20° and PLB at 0° (A20P0), (4) AMB at 20° and PLB at 20° (A20P20), and (5) AMB at 20° and PLB at 45° (A20P45). All the grafts were tensioned at a constant stress level. Anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) at 30° and 90° of knee flexion applied with manual maximum load were measured before graft insertion and in each setting using a navigation system. A pivot-shift test was also evaluated manually with modified International Knee Documentation Committee criteria in each setting.

RESULTS

A20 was less constrained than A20P20 and A20P45 in ATT at 30° and less constrained than A20P45 in IR at 30°. P20 was less constrained than any other settings in ATT at 30° and less constrained than A20P45 in IR at 30°. A20P0 was less constrained than A20P45 in IR at 30° and in ER at 30°. Grade 1 pivot-shift phenomenon persisted in 8 cases in P20, in 4 cases in A20, and in 3 cases in A20P0, whereas no case showed a positive pivot-shift result in A20P20 and A20P45.

CONCLUSION

In this in vivo laboratory model, double-bundle ACL reconstruction with fixation of AMB at 20° and PLB at 20° or 45° restored better stability than single AMB or single PLB reconstruction in which the graft was of smaller size.

CLINICAL RELEVANCE

In double-bundle ACL reconstruction, fixation of the PLB at 0° might be looser and function worse compared with that of PLB at 20° or 45° when the AMB is fixed at 20°, with the individual variability that should lead to caution until it can be better assessed by surgeons.