Healthy Tendon Stem Cell-Derived Exosomes Promote Tendon-To-Bone Healing of Aged Chronic Rotator Cuff Tears by Breaking the Positive-Feedback Cross-Talk between Senescent Tendon Stem Cells and Macrophages through the Modulation of Macrophage Polarization

The re-tear rate of rotator cuff tears (RCT) after surgical repair is high, especially in aged patients with chronic tears. Senescent tendon stem cells (s-TSCs) generally exist in aged and chronically torn rotator cuff tendons and are closely associated with impaired tendon-to-bone healing results. The present study found a positive feedback cross-talk between s-TSCs and macrophages. The conditioned medium (CM) from s-STCs can promote macrophage polarization mainly toward the M1 phenotype, whose CM reciprocally accelerated further s-TSC senescence. Additional healthy tendon stem-cells derived exosomes (h-TSC-Exos) can break this positive feedback cross-talk by skewing macrophage polarization from the M1 phenotype to the M2 phenotype, attenuating s-TSCs senescence. S-TSC senescence acceleration or attenuation effects induced by M1 or M2 macrophages are associated with the inhibition or activation of the bone morphogenetic protein 4 signaling pathway following RNA sequencing analysis. Using an aged-chronic rotator cuff tear rat model, it is found that h-TSC-Exos can shift the microenvironment in the tendon-to-bone interface from a pro-inflammatory to an anti-inflammatory type at the acute postoperative stage and improve the tendon-to-bone healing results, which are associated with the rejuvenated s-TSCs. Therefore, this study proposed a potential strategy to improve the healing of aged chronic RCT.

Enhancement of Tendon-to-Bone Healing: Choose a Monophasic or Hierarchical Scaffold?

BACKGROUND

To enhance the healing of tendon to bone, various biomimetically hierarchical scaffolds have been proposed. However, the fabrication of such scaffolds is complicated. Furthermore, the most significant result after a routine repair is loss of the transition zone between the tendon and bone, whose main components are similar to fibrocartilage.

PURPOSE

To compare tendon-to-bone healing results in a rabbit model using a monophasic graft (decellularized fibrocartilage graft; DFCG) and hierarchical graft (decellularized tendon-to-bone complex; DTBC) that contain the native hierarchical enthesis.

STUDY DESIGN

Controlled laboratory study.

METHODS

DFCG and DTBC were harvested from allogenic rabbits. A rabbit model of a chronic rotator cuff tear was established, and 3 groups were assessed: direct repair or repair with DFCG or DTBC fixed between the tendon and bone. Hierarchical evaluations of the repaired tendon-to-bone interface were performed with regard to the tendon zone, transition zone, and bone zone using histological staining and micro-computed tomography scanning. Biomechanical analysis was performed to evaluate the general healing strength.

RESULTS

The healing results in the tendon zone exhibited no significant difference among the 3 groups at any time point. In the transition zone, the grade in the direct repair group was significantly lower than that in the DFCG and DTBC groups at 4 weeks, and the grade in the DFCG group was significantly lower than that in the DTBC group at this time point. However, any significant difference between the DFCG group and DTBC group could no longer be detected at 8 and 16 weeks, which was inconsistent with the results of the biomechanical analysis. Micro-computed tomography analysis showed no significant difference among the 3 groups with regard to bone mineral density at 16 weeks.

CONCLUSION

A monophasic DFCG was able to achieve enhanced tendon-to-bone healing similar to that with hierarchical DTBC over the long term, with regard to both histological and biomechanical properties.

CLINICAL RELEVANCE

Fabrication of a monophasic scaffold instead of a hierarchical scaffold to promote regeneration and remodeling of a transition zone, which was mainly composed of fibrocartilaginous matrix between the tendon and bone, may be sufficient to enhance tendon-to-bone healing.

Three-Dimensional Bioprinting of a Structure-, Composition-, and Mechanics-Graded Biomimetic Scaffold Coated with Specific Decellularized Extracellular Matrix to Improve the Tendon-to-Bone Healing

Healing of a damaged tendon-to-bone enthesis occurs through the formation of fibrovascular scar tissue with greatly compromised histological and biomechanical properties instead of the regeneration of a new enthesis due to the lack of graded tissue-engineering zones in the interface during the healing process. In the present study, a structure-, composition-, and mechanics-graded biomimetic scaffold (GBS) coated with specific decellularized extracellular matrix (dECM) (GBS-E) aimed to enhance its cellular differentiation inducibilities was fabricated using a three-dimensional (3-D) bioprinting technique. In vitro cellular differentiation studies showed that from the tendon-engineering zone to the bone-engineering zone in the GBS, the tenogenic differentiation inducibility decreased in correspondence with an increase in the osteogenic differentiation inducibility. The chondrogenic differentiation inducibility peaked in the middle, which was in consistent with the graded cellular phenotypes observed in a native tendon-to-bone enthesis, while specific dECM coating from the tendon-engineering zone to the bone-engineering zone (tendon-, cartilage-, and bone-derived dECM, respectively) further enhanced its cellular differentiation inducibilities (GBS-E). In a rabbit rotator cuff tear model, histological analysis showed that the GBS-E group exhibited well-graded tendon-to-bone differentiated properties in the repaired interface that was similar to a native tendon-to-bone enthesis at 16 weeks. Moreover, the biomechanical properties in the GBS-E group were also significantly higher than those in other groups at 16 weeks. Therefore, our findings suggested a promising tissue-engineering strategy for the regeneration of a complex enthesis using a three-dimensional bioprinting technique.

Loading Mesenchymal Stem Cell-Derived Exosomes Into a Traditionally Designed Rotator Cuff Patch: A Potential Strategy to Enhance the Repair of Chronic Rotator Cuff Tear Associated With Degenerative Changes

BACKGROUND

Retraction and degenerative changes of chronic rotator cuff tears limit the healing capacity after routine surgical repair.

PURPOSE

To fabricate a mesenchymal stem cell-derived exosome (MSC-Exos) loaded patch and evaluate the effect of this patch on the activity of rabbit tenocytes in vitro and on the repair of chronic rotator cuff tears associated with degenerative changes in vivo.

STUDY DESIGN

Controlled laboratory study.

METHODS

The MSC-Exos loaded patch was fabricated using a dynamic wet-spinning system. In the in vitro studies, the proliferation and migration activities of tenocytes were evaluated by culturing tenocytes with saline, a fiber-aligned patch, or an MSC-Exos loaded patch. In the in vivo studies, a rabbit model of chronic rotator cuff tear was established and directly repaired, repaired with fiber-aligned patch augmentation (RFPA group), and repaired with MSC-Exos loaded patch augmentation (REPA group). Histological and biomechanical analyses were performed at 4, 8, and 12 weeks after surgery.

RESULTS

An MSC-Exos loaded patch with inner aligned fibers, a loose microstructure, and reliable initial strength was fabricated using a dynamic wet-spinning system. The MSC-Exos loaded patch significantly promoted tenocyte proliferation and migration activities in vitro. In vivo, the REPA group exhibited significantly higher tendon maturing scores at 8 and 12 weeks after surgery compared with both the control and the RFPA groups. Fatty infiltration was significantly reduced in the REPA group at 4, 8, and 12 weeks compared with both the control and the RFPA groups. Biomechanical properties, including load to failure and stress, were also significantly improved at 12 weeks in the REPA group compared with both the control and the RFPA groups.

CONCLUSION

Results in the present study suggested that an MSC-Exos loaded patch was able to enhance the repair of a chronic rotator cuff tear by providing mechanical support and minimizing degeneration.

CLINICAL RELEVANCE

This work supported the idea that loading bioactive MSC-Exos into a traditionally designed rotator cuff patch might exert a better effect on the repair of chronic rotator cuff tears than augmented patch repair alone.

Reconstruction for Chronic ACL Tears with or without Anterolateral Structure Augmentation in Patients at High Risk for Clinical Failure: A Randomized Clinical Trial

BACKGROUND

The purpose of this trial was to determine whether anterior cruciate ligament reconstruction (ACLR) with anterolateral structure augmentation (ALSA) would result in better clinical outcomes in patients with a high risk of clinical failure.

METHODS

From February 2017 to June 2018, 120 young, active adults with chronic anterior cruciate ligament injury and high risk of clinical failure were randomized. The patients were followed for >2 years, with 5 being lost to follow-up and 1 being withdrawn from the study. Clinical characteristics, operative findings, and postoperative clinical outcomes were analyzed.

RESULTS

The analysis included data from 114 patients, including 95 men and 19 women with a mean age (and standard deviation) of 30.1 ± 6.7 years in the ACLR group and 30.1 ± 6.4 years in the ALSA group. The rate of clinical failure was 20.4% (11 of 54 patients) and 3.3% (2 of 60 patients) in the ACLR and ALSA groups, respectively (difference, 17.1%; 95% confidence interval [CI], 5.3% to 29.8%; p = 0.007). Significantly higher rates of return to the preinjury level of sports (48.3% versus 27.8%; difference, 20.5%; 95% CI, 2.7% to 36.6%; p = 0.024) and to a competitive level of play (63.3% versus 42.6%; difference, 22.3%; 95% CI, 4.1% to 38.8%; p = 0.027) was found in the ALSA group.

CONCLUSIONS

Compared with isolated ACLR, combined ACLR and ALSA resulted in a reduction in persistent rotatory laxity and higher rates of return to preinjury and competitive levels of play at 2 years of follow-up in the population studied. Our study suggests that patients with high risk of clinical failure appear to be candidates for the ALSA approach.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Adipose Stem Cell-Derived Exosomes Recover Impaired Matrix Metabolism of Torn Human Rotator Cuff Tendons by Maintaining Tissue Homeostasis

BACKGROUND

Adipose stem cell-derived exosomes (ASC-Exos) are reported to effectively prevent muscle atrophy and degeneration of torn rat rotator cuff, but their influence on human samples and their potential mechanism are still unclear.

PURPOSE

We aimed to investigate the effects of ASC-Exos on the metabolic activities of torn human rotator cuff tendons and explore the potential mechanism behind it.

STUDY DESIGN

Controlled laboratory study.

METHODS

Diseased supraspinatus tendons were harvested from 15 patients with a mean ± SD age of 65.8 ± 3.2 years who underwent reverse shoulder arthroplasty for chronic rotator cuff tears associated with glenohumeral pathological changes. Each tendon was dissected into 3 × 4 × 4-mm explants: the ones derived from the same tendon were placed into 12-well plates and cultured in complete culture media (control) or in complete culture media supplemented with ASC-Exos for 72 hours. Afterward, the concentrations of cytokines secreted into the culture media-including interleukin 1β (IL-1β), IL-6, IL-8, and matrix metalloproteinase 9 (MMP-9)-were measured using enzyme-linked immunosorbent assay (ELISA). Tendons were stained with hematoxylin and eosin and immunohistochemistry (type I and III collagens) for histological analyses. Moreover, the expression of anabolic genes (TIMP-1 and TIMP-3; type I and III collagen encoding) and catabolic genes (MMP-9 and MMP-13) in tendons were measured using real-time quantitative polymerase chain reaction. Phosphorylated AMPKα and Wnt/β-catenin pathways were assayed by western blotting to explore the potential mechanism of action of ASC-Exos.

RESULTS

Secretion of proinflammatory cytokines, including IL-1β, IL-6, and MMP-9, was significantly reduced in the ASC-Exos group as compared with the control group. Supraspinatus tendons in the ASC-Exos group exhibited superior histological properties, as demonstrated by higher tendon maturing scores and more type I collagen content, but there was no significant difference in type III collagen content between groups. Expression of MMP-9 and MMP-13 genes was decreased in the ASC-Exos group versus the control group. Increased expression of type I and III collagens and an elevated type I/III ratio were found in the ASC-Exos group when compared with the control group. There was no significant difference in the secretion of IL-8 and expression of TIMP-1 and TIMP-3 genes between the ASC-Exos and control groups. Western blotting revealed that ASC-Exos enhanced phosphorylated AMPKα and decreased β-catenin levels to prevent tendon degeneration.

CONCLUSION

ASC-Exos maintained metabolic homeostasis of torn human rotator cuff tendons to improve their histological properties, which might be achieved by enhancing AMPK signaling to suppress Wnt/β-catenin activity.

CLINICAL RELEVANCE

ASC-Exos could be used as an effective biological tool to promote healing in torn human rotator cuff tendons.

Radiographic Reference Points Do Not Ensure Anatomic Femoral Fixation Sites in Medial Patellofemoral Ligament Reconstruction: A Quantified Anatomic Localization Method Based on the Saddle Sulcus

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is one of the main treatments for lateral patellar translation. Based on intraoperative true lateral radiographs, the accepted methods for femoral MPFL tunnel location are potentially inaccurate. Direct assessment of anatomic characteristics during surgery through palpation of the anatomic landmarks involving the saddle sulcus might help eliminate tunnel malposition.

HYPOTHESIS

The saddle sulcus is a reliable osseous landmark where the MPFL attaches for tunnel placement.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 9 fresh-frozen unpaired human cadaveric knees were dissected; MPFL insertion point and relative osseous structures were marked. Three-dimensional images and transformed true lateral radiographs were obtained for analysis; 3 previously reported radiographic reference points for MPFL femoral tunnel placement were determined on all images and compared with the anatomic insertion.

RESULTS

A saddle sulcus consistently existed where the MPFL was attached, located at 11.7 ± 5.9 mm from the apex of the adductor tubercle (AT) to the medial epicondyle (ME), 62.8% of the average distance between the apexes of the AT and ME, and 5.6 ± 2.8 mm perpendicular-posterior to the border connecting the AT and ME. The reported radiographic reference points were located at average distances of 6.2 ± 3.2 mm (Schöttle method), 5.9 ± 2.3 mm (Redfern method), and 7.3 ± 6.6 mm (Fujino method) from the saddle sulcus center on the true lateral radiographs.

CONCLUSION

The saddle sulcus was a reliable landmark where the MPFL was anatomically attached, located approximately 12 mm from the AT to the ME (approximately 60% along a line from the AT to the ME) and 6 mm perpendicular-posterior to the border connecting the apexes of the AT and ME. Additionally, the saddle sulcus position presented variability on the femoral aspect of different knees. All of the average direct distances from the sulcus to the reference radiographic points exceeded 5 mm, and tunnel localizations on a true lateral radiograph were inaccurate.

CLINICAL RELEVANCE

This study demonstrates the potential precise position of the saddle sulcus, according to the ME and AT, as a reliable anatomic landmark for MPFL femoral tunnel location. Radiographic reference points were not accurate during MPFL reconstruction. Direct palpation of the landmarks might be effective for femoral MPFL tunnel placement.

Tissue-Engineered Decellularized Allografts for Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) reconstruction with allografts is limited by high immunogenicity, poor cellularization, and delayed tendon-bone healing. Decellularized tendons (DAs) have been used as bioscaffolds to reconstruct ligaments with variable success. In the study, four kinds of decellularized allogeneic hamstring tendons were prepared and their microstructure and cytocompatibility were examined in vitro. The results showed that decellularized allografts neutralized by 5% calcium bicarbonate had typical reticular and porous microstructures with optical cytocompatibility. Tissue-engineering decellularized allografts (TEDAs) were prepared with the selected decellularized allografts and tendon stem/progenitor cells and used for ACL reconstruction in a rabbit model. Histological staining showed that the TEDAs promoted cellular infiltration and new vessel formation significantly and improved tendon-bone healing moderately compared to decellularized allografts. Better macroscopic scores and biomechanical results were observed in TEDA groups, but there were no significant differences between DA and TEDA groups at months 1, 2, and 3 postoperatively. Immunohistochemical data showed that the tissue-engineering decellularized allografts enhanced the expression of collagen I at each timepoint and collagen III at months 1 and 2. ELISA analysis showed that the tissue-engineering decellularized allografts reduced the secretion of IgE and IL-1β within 1 month and promoted the secretion of IL-2, IL-4, IL-10, and IL-17 after 1 month. The results showed that tissue-engineering decellularized allografts strengthened intra-articular graft remodeling significantly and provided moderate improvements in tendon-bone healing by creating more suitable immune responses than decellularized allografts. The study revealed that tissue-engineering decellularized allografts as a promising option for ACL reconstruction could achieve more favorable outcomes.

Anterior Cruciate Ligament Reconstruction in a Rabbit Model Using a Decellularized Allogenic Semitendinous Tendon Combined with Autologous Bone Marrow-Derived Mesenchymal Stem Cells

As a regular adoptable material for anterior cruciate ligament (ACL) reconstruction, free tendon allograft exhibits unsatisfactory outcomes, such as retarded ligamentization and tendon–bone integration. The application of bone marrow‐derived mesenchymal stem cells (BMSCs), as well as a decellularized free tendon allograft developed by our group, was proven to be effective in improving ACL reconstruction results. This study aimed to investigate the efficacy and feasibility of decellularized allogenic semitendinous tendon (ST) combined with autologous BMSCs used as a substitute to free tendon allograft in a rabbit model. This study finally shows that the decellularized allogenic ST combined with autologous BMSCs could significantly improve ACL reconstruction results compared with allograft. stem cells translational medicine2019;8:971&982

Time-Dependent Effects of Arthroscopic Conditions on Human Articular Cartilage: An In Vivo Study

PURPOSE

To assess time-dependent effects of arthroscopic conditions on human articular cartilage in vivo.

METHODS

From each of 10 patients undergoing multiligament reconstruction of the knee under our routine arthroscopic conditions (gravity irrigation of 0.9% normal saline solution at room temperature with 150 cm H₂O [110 mm Hg] pressure and pneumatic tourniquet under 270 mm Hg pressure), cartilage specimens were harvested from the lateral edge of the femoral notch at the beginning of the operation (baseline) and at 15-, 30-, 45-, and 60-minute time points during the operation. H&E staining and safranin O staining were used to evaluate the tissue structure, chondrocytes, and extracellular matrix (ECM) of the articular cartilage. Chondrocyte viability was evaluated, and a biochemical examination of the ECM was performed to detect changes in glycosaminoglycan and collagen content. The expression levels of genes associated with proinflammatory cytokines, ECM metabolism, and chondrocyte apoptosis of the articular cartilage were evaluated.

RESULTS

At the 45- and 60-minute time points, an obvious impairment of tissue structure, a significant decrease in glycosaminoglycan content, and a significantly lower percentage chondrocyte viability were observed, as compared with baseline (P < .05). Regarding the tissue collagen content, no significant change was detected at any time point (P > .05). The gene expression examination at the 45- and 60-minute time points detected significant upregulation of interleukin 1β and tumor necrosis factor α (P < .05), indicating an inflammatory response by the chondrocytes, and significant upregulation of aggrecanase 1 (P < .05), which indicates catabolism or the disturbance of aggrecan metabolism.

CONCLUSIONS

Under current arthroscopic conditions, an operative duration of 45 minutes or longer can cause detrimental structural, biochemical, and metabolic effects on human articular cartilage.

CLINICAL RELEVANCE

Arthroscopic skills should always be improved to reduce operation time and thus minimize the potential detrimental effects of arthroscopic conditions on articular cartilage.

[EXPRESSIONS OF LIGAMENT REMODELING RELATED GENES IN RABBIT MODEL OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH PRESERVING TIBIAL RESIDUAL FIBERS]

OBJECTIVE

To observe the effect of preserving tibial residual fibers on the expressions of ligament remodeling related genes in rabbit anterior cruciate ligament (ACL) reconstruction model.

METHODS

Sixty healthy adult New Zealand white rabbits were randomly divided into 4 groups: normal control group (group A, n = 6), sham-operation group (group B, n = 18), non tibial remnant preserved group (group C, n = 18), and tibial remnant preserved group (group D, n = 18). At 2, 6, and 12 weeks after operation, the ligament tissue was harvested to detect the mRNA expressions of collagen type 1A1 (COL1A1), collagen type 3A1 (COL3A1), transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), growth-associated protein 43 (GAP-43), and neurotrophin 3 (NT-3) by real-time fluorescent quantitative PCR.

RESULTS

At each time point, there was no significant difference in the mRNA expressions of COL1A1, COL3A1, VEGF, and NT-3 between group A and group B (P > 0.05). In group D, the mRNA expressions of COL1A1, COL3A1, TGF-β1, and GAP-43 significantly increased when compared with those of group C at 6 weeks after operation (P < 0.05); an increased level of VEGF mRNA was also detected in the group D at 12 weeks after operation (P < 0.05); and an increased level of NT-3 mRNA was also observed in group D at 2 and 12 weeks after operation (P < 0.05).

CONCLUSION

There is a time-dependent manner of angiogenesis-promoting, repair-related, and nerve-related gene expressions after ACL reconstruction with preserving tibial residual fibers during the process of ligamentization. Furthermore, the remnant preservation in ACL reconstruction can promote the expressions of related genes in some time points.

Decellularized Versus Fresh-Frozen Allografts in Anterior Cruciate Ligament Reconstruction: An In Vitro Study in a Rabbit Model

BACKGROUND

The common fresh-frozen allografts that are used for anterior cruciate ligament (ACL) reconstructions behave slower during the remodeling process and produce weaker tendon-bone integrations than do autografts. Decellularization of allogenic tendons results in a clean and porous collagen scaffold with low antigenicity and high compatibility, which may be more suitable for ACL reconstructions.

HYPOTHESIS

Allograft decellularization will result in a tissue structure with suitable mechanical characteristics for ACL reconstruction, thereby promoting graft remodeling and enhancing tendon-bone healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Decellularized allograft tissues were prepared with a pH-modified decellularization process and evaluated for their biocompatibility and biomechanical character in vitro. Eighty New Zealand White rabbits were divided into 2 groups, with 40 in each group, to receive ACL reconstruction with either fresh-frozen (common) allografts or decellularized allografts on both knees. At 2, 4, 8, and 12 weeks postoperatively, the rabbits were euthanized for biomechanical testing, micro-computed tomography analysis, and histologic analysis.

RESULTS

The pH-modified decellularized allograft tissues kept excellent biocompatibility and biomechanical character during the in vitro study. Biomechanical testing indicated that the decellularized allograft had significantly higher ultimate load (P = .02) and stiffness (P = .01) levels than the common allograft at 12 weeks, and there was no significant difference between the 2 groups at any other time point. The micro-CT evaluation determined significantly higher bone mineral density (P < .01) in the decellularized allograft group than that in the common allograft group at 12 weeks, but no difference between the 2 groups was observed at any other time point. Regarding bone volume/total volume, there was no difference between the 2 groups at any time point. Fibroblast ingrowths, vascular formation, and connective tissue formation in the tendon-bone interface were better in the decellularized group within 8 weeks. New bone formation was more common in the decellularized allograft group. The collagen birefringence was restored more quickly in the decellularized allograft group than in the common allograft group at all time points.

CONCLUSION

The use of pH-modified decellularized allografts compared with the common allografts resulted in better cellularity, vascularity, collagen matrix remolding, new bone formation around the graft, enhanced tendon-bone healing, and higher ultimate failure load and stiffness of the graft after ACL reconstruction in the rabbit model.

CLINICAL RELEVANCE

The pH-modified decellularized allograft may be a better graft option than the common fresh-frozen allograft for knee ligament reconstructions.

Ligamentization of Autogenous Hamstring Grafts After Anterior Cruciate Ligament Reconstruction: Midterm Versus Long-term Results

BACKGROUND

In previous studies, unimodal, small-diameter collagen fibrils have been commonly observed as the final collagen ultrastructure of the implanted grafts used in anterior cruciate ligament (ACL) reconstruction. However, the native ACL and hamstring tendon show bimodal collagen fibril distribution, consisting of both large- and small-diameter collagen fibrils.

HYPOTHESIS

Bimodal collagen fibril distribution of the graft is a common phenomenon after ACL reconstruction with hamstring tendon grafts and is time dependent.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 52 patients who underwent double-bundle ACL reconstruction using autogenous hamstring tendons and who also underwent second-look arthroscopic surgery were enrolled. The patients were divided into 2 groups according to the time interval between the 2 operations: the midterm group (27 patients), with a 13- to 30-month time interval between operations, and the long-term group (25 patients) with a 31- to 62-month interval. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues were harvested from 9 patients who underwent total knee replacement, and biopsy specimens of the to-be-grafted semitendinosus tendon tissues were also harvested from another 9 patients who underwent ACL reconstruction with hamstring tendons, which were designated as normal controls. Graft vascularity, cellularity, metaplasia, cellular metabolism, and collagen fibril distribution were analyzed.

RESULTS

Large-diameter (>100 nm) collagen fibrils were detected in 81.5% of the specimens in the midterm group and in 68.0% of the specimens in the long-term group. A typical bimodal distribution mode was observed in 62.6% of the specimens in the midterm group and in 52.0% of the specimens in the long-term group. There was no significant difference between groups with respect to the presence of large-diameter collagen fibrils, bimodal distribution, graft vascularity, cellularity, metaplasia, or cellular metabolic status.

CONCLUSION

Graft ultrastructural maturation, characterized by large-diameter collagen fibrils and a bimodal collagen fibril distribution, is a common phenomenon and is not time dependent in the midterm to long term.

CLINICAL RELEVANCE

After hamstring tendon ACL reconstruction, the implanted grafts can transform into ACL-like tissue with a similar ultrastructure and metabolism, implying their usefulness as grafts.

Arthroscopic treatment of acute acromioclavicular joint dislocation by coracoclavicular ligament augmentation

PURPOSE

Coracoclavicular (CC) ligament augmentation has been a method to treat acromioclavicular (AC) joint dislocation in recent years. The purpose of this paper is to describe our arthroscopic CC ligament augmentation technique in treating type III and V acute AC joint dislocations and to report the early clinical and radiological results.

METHODS

From 2010 to 2011, twelve patients suffering from acute type III or V AC joint dislocations were arthroscopically treated in our department, by CC ligament augmentation after AC joint reduction. The post-operative outcomes were assessed through physical examination, radiographic examination and the Constant-Murley Shoulder Score.

RESULTS

All patients post-operatively experienced anatomical reduction in their AC joint dislocation. No intraoperative complications occurred. At a mean follow-up at 24 months (ranging from 18 to 32 months), the mean Constant-Murley Shoulder Score significantly improved from 24.3 pre-operatively to 91.1 post-operatively. No neurovascular complications or secondary degenerative changes of the AC joint were detected in any of the patients. In one case, a second dislocation occurred 1 month post-operation because the patient had had another traumatic injury. This patient accepted a revision operation, but his AC joint eventually fixated into a subluxated position after his second injury.

CONCLUSION

Based on the resultant successful repair in all cases, the arthroscopic CC ligament augmentation method has thus far proven to be a safe and reliable technique for treatment of acute type III or V AC joint dislocation.

CLINICAL RELEVANCE

The arthroscopic CC ligament augmentation with a flip button/polyethylene belt repair is an efficient method to treat acute type III and V AC joint dislocations which should be popularized.

LEVEL OF EVIDENCE

IV.

Screening for characteristic genes in osteoarthritis induced by destabilization of the medial meniscus utilizing bioinformatics approach

OBJECTIVE

To explore the underlying molecular mechanism of the development of OA (osteoarthritis).

METHODS

The expression profile dataset GSE26475 was downloaded from Gene Expression Omnibus database. A total of 21 samples were available, including knee joint samples from OA mice induced by DMM (Destabilization of the medial meniscus) surgery (6h, 3d, 7d), mice undergoing sham (only capsulotomy) surgery (6h, 3d, 7d) and the age matched Naïve mice (normal controls) that were not operated on. The differentially expressed genes (DEGs) were identified and the KEGG pathway enrichment analysis was conducted for all DEGs.

RESULTS

The number of DEGs between the DMM-induced mice at different times after surgery and normal controls was different that it decreased from 6h to 3d while increased at 7d. The same was true for the change of the number of DEGs between DMM and sham groups. Further analysis revealed that the DEGs between DMM and normal controls were mainly involved in the signaling and inflammation related pathways. Total 16 DEGs between DMM and sham groups at 7d were all involved in the Parkinson's disease, Oxidative phosphorylation and Alzheimer's disease pathways.

CONCLUSION

The results presented here may help us to understand the molecular mechanism of OA.

Biological augmentation of rotator cuff repair using bFGF-loaded electrospun poly(lactide-co-glycolide) fibrous membranes

Clinically, rotator cuff tear (RCT) is among the most common shoulder pathologies. Despite significant advances in surgical techniques, the re-tear rate after rotator cuff (RC) repair remains high. Insufficient healing capacity is likely the main factor for reconstruction failure. This study reports on a basic fibroblast growth factor (bFGF)-loaded electrospun poly(lactide-co-glycolide) (PLGA) fibrous membrane for repairing RCT. Implantable biodegradable bFGF-PLGA fibrous membranes were successfully fabricated using emulsion electrospinning technology and then characterized and evaluated with in vitro and in vivo cell proliferation assays and repairs of rat chronic RCTs. Emulsion electrospinning fabricated ultrafine fibers with a core-sheath structure which secured the bioactivity of bFGF in a sustained manner for 3 weeks. Histological observations showed that electrospun fibrous membranes have excellent biocompatibility and biodegradability. At 2, 4, and 8 weeks after in vivo RCT repair surgery, electrospun fibrous membranes significantly increased the area of glycosaminoglycan staining at the tendon-bone interface compared with the control group, and bFGF-PLGA significantly improved collagen organization, as measured by birefringence under polarized light at the healing enthesis compared with the control and PLGA groups. Biomechanical testing showed that the electrospun fibrous membrane groups had a greater ultimate load-to-failure and stiffness than the control group at 4 and 8 weeks. The bFGF-PLGA membranes had the highest ultimate load-to-failure, stiffness, and stress of the healing enthesis, and their superiority compared to PLGA alone was significant. These results demonstrated that electrospun fibrous membranes aid in cell attachment and proliferation, as well as accelerating tendon-bone remodeling, and bFGF-loaded PLGA fibrous membranes have a more pronounced effect on tendon-bone healing. Therefore, augmentation using bFGF-PLGA electrospun fibrous membranes is a promising treatment for RCT.

Arthroscopic glenoid bone grafting with nonrigid fixation for anterior shoulder instability: 52 patients with 2- to 5-year follow-up

BACKGROUND

The healing rate and clinical outcomes of glenoid bone grafting with nonrigid fixation for patients with recurrent anterior shoulder instability are unknown.

HYPOTHESIS

Glenoid bone grafting with nonrigid fixation can yield satisfactory results for patients with recurrent anterior shoulder instability with regard to graft healing and the restoration of shoulder stability.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 52 patients with recurrent anterior shoulder instability underwent Bankart or bony Bankart repair as well as arthroscopic glenoid bone grafting. Allogenic bicortical iliac grafts were used. Instead of firm fixation, the grafts were tethered to the glenoid by sutures from anchors placed in the glenoid surface. Follow-up occurred at 3, 6, 12, and 24 months. Computed tomography and magnetic resonance imaging examinations were performed immediately after surgery and at each follow-up visit to evaluate the healing of the graft and the changes in the repaired capsule-labrum structure. Functional evaluations were taken at 24 months with the Oxford Shoulder Instability Score and the Rowe Score for Shoulder Instability. For the patients who underwent surgery 2.5 years earlier, an additional review was conducted to evaluate the latest stability status of the shoulder. Failure was defined as recurrence of dislocation or instability.

RESULTS

The mean follow-up time was 39 months (range, 24-64 months). In all cases, the grafts healed to the glenoid at 3 or 6 months, and glenoid remodeling was complete within 12 months; in most cases, a robust bone-capsule structure formed on the anterior side of the glenoid. The glenoid defect area changed from 32.7% ± 8.7% (range, 10.7% to 53.9%) to -16.3% ± 3.3% (range, -26.7% to 5.9%), and the glenoid defect width changed from 28.3% ± 8.7% (range, 10.4% to 54.5%) to -16.9% ± 7.3% (range, -33.4% to 2.8%). Compared with the presumed normal glenoid, the final glenoid surface area increased in 94.2% of patients and final glenoid width increased in 96.2% of patients. One patient experienced redislocation and 2 experienced a sense of instability without dislocation, which resulted in a failure rate of 5.8%. Six patients exhibited slight pain. The Oxford score improved from 29.7 ± 5.6 preoperatively to 42.4 ± 3.3 at 2 years postoperatively, and the Rowe score improved from 34.7 ± 6.1 preoperatively to 91.8 ± 2.8 at 2 years postoperatively.

CONCLUSION

In this study, arthroscopic glenoid bone grafting with nonrigid fixation in combination with Bankart repair resulted in 100% graft healing and the satisfactory restoration of shoulder stability.

Optimal graft length for anterior cruciate ligament reconstruction: a biomechanical study in beagles

The anterior cruciate ligament (ACL) is a major ligament that helps maintain the stability of the knee joint. Injury to the ACL can be treated by replacing the torn ligament. This study determined the optimal flexor tendon length in the bone tunnel in ACL reconstruction.Autologous ACL reconstruction was performed using a flexor tendon in 54 male beagles, with the graft length in the bone tunnel at 5, 9, 13, 17, 21, and 25 mm (9 dogs per graft length). The maximum tensile strength and stiffness of the reconstructed joint (tibia-ACL-femur triad) were recorded at 45, 90, and 180 days after ACL reconstruction (6 joints per time point). The experiment also included an intact control group (3 dogs) and a control group tested immediately after the reconstruction (3 dogs). For the intact control group, the normal ACL (unreconstructed) and flexor tendon mechanical testing was performed. For the other control group, the normal ACL (unreconstructed) mechanical testing was performed first and then mechanical testing of the specimens was performed immediately after reconstruction. The maximum tensile strength and stiffness of the reconstructed tibia-ACL-femur triad increased with time after reconstruction, regardless of the graft length in the bone tunnel. Maximum tensile strength and stiffness of the grafts increased with graft length but reached a plateau at 17 mm. Optimal strength and stiffness of the reconstructed ACL are achieved with 17-mm grafts.

The effect of platelet-rich plasma on patterns of gene expression in a dog model of anterior cruciate ligament reconstruction

BACKGROUND

Autologous platelet-rich plasma (PRP) has been investigated as a potential promoter of tendon healing and has an enhancing effect on the anterior cruciate ligament (ACL) graft maturation process. However, the influence of PRP on the synthesis and degradation of the extracellular matrix during the ACL graft remodeling process has never been investigated.

MATERIALS AND METHODS

Healthy and mature beagle dogs were randomly assigned to one of four groups: in group I (PRP group), ACL grafts were treated with PRP; in group II (control group), ACL grafts were treated with saline; in group III (sham group), only the knee joints were exposed; in group IV (normal control group), no surgery was performed to the knees. Ligament tissue was dissected at 2, 6, and 12 wk after surgery, and real-time PCR was performed using primers for growth factor-β1 (TGF-β1), collagen type1A1 (COL1Al), collagen type3A1 (COL3A1), decorin, biglycan, matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-13 (MMP-13), and tissue inhibitor of metalloproteinase-1 (TIMP-1).

RESULT

In group I, the messenger RNA (mRNA) levels of collagen type 1A1, biglycan, and MMP-1 all increased 2, 6, and 12 wk after surgery, compared with group II (P < 0.05). At 2 and 6 wk after surgery, increased levels of COL3A1, MMP-1, and MMP-13 mRNA were also detected in group I (P < 0.05). Increased levels of TGF-β1 mRNA was observed at 6 and 12 wk in group I after surgery (P < 0.05).

CONCLUSIONS

During the graft remodeling process, we observed a time-dependent change of gene expression following ACL reconstruction surgery. Furthermore, our results demonstrate that PRP alters the expression of some target genes at certain time points, especially during the early stages of graft remodeling, which might explain the enhancing effect of PRP on the ACL graft maturation process.

[Effectiveness of arthroscopic treatment for synovial chondromatosis]

OBJECTIVE

To explore the technique of arthroscopic treatment of synovial chondromatosis of the hip and to evaluate its effectiveness.

METHODS

Between July 2009 and June 2011, 15 patients with synovial chondromatosis of the hip underwent arthroscopic synovectomy and removal of loose bodier. Of 15 patients, 11 were male and 4 were female, aged from 21 to 45 years with an average of 33.1 years. The location was the left side in 6 cases and the right side in 9 cases. The disease duration was 12-43 months (mean, 23 months) Pain and functional motion limitation were the main clinical symptoms. The visual analogue scale (VAS) score was 5.8 +/- 1.1; the range of motion (ROM) of the hip was (149.8 +/- 27.5)degrees; the Harris hip score was 54.5 +/- 13.3.

RESULTS

All incisions healed by first intention. All the patients were followed up 6 months to 2 years (mean, 17.4 months). At last follow-up, the VAS score was 2.0 +/- 1.2; the ROM of the hip was (258.3 +/- 35.4)degrees; the Harris hip score was 93.0 +/- 18.7; and the above indexes were significantly improved when compared with preoperative values (P < 0.05). No recurrence was found on postoperative MRI.

CONCLUSION

Arthroscopic treatment of synovial chondromatosis of the hip has the advantages of minimal invasion, quick recovery, and best recovery of hip function and ROM.

Medial patellofemoral ligament reconstruction using semitendinosus tendons: polyester suture augmentation versus nonaugmentation

BACKGROUND

The comparative clinical outcome of medial patellofemoral ligament reconstruction (MPFLR) using semitendinosus tendons with and without polyester suture augmentation for recurrent patellar instability is unknown.

HYPOTHESIS

Medial patellofemoral ligament reconstruction with polyester suture augmentation will yield better results than MPFLR without augmentation for recurrent patellar instability in adults.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

One hundred patients with recurrent patellar instability receiving MPFLR using semitendinosus tendons were randomly divided into 2 groups either with or without polyester suture augmentation. Tibial tubercle transfer was performed in most cases. Follow-ups were performed at 12, 24, and 60 months postoperatively, and computed tomography (CT) was performed immediately after the operation and at follow-up. The passive patellar glide test was performed before surgery, immediately after MPFLR during the operation, and at each follow-up point. The degree of knee function was evaluated preoperatively and at 2 and 5 years postoperatively using the International Knee Documentation Committee, Lysholm, and Kujala rating scales. Redislocation or multiple episodes of patellar instability were considered failures.

RESULTS

Forty-two patients in the augmentation group and 43 patients in the nonaugmentation group were followed for 5 years and received complete serial CT examinations and functional evaluations. The correction of the static patellar position deteriorated over time in the nonaugmentation group but not in the augmentation group. The results of the passive patellar glide test indicated stable patellae in all patients immediately after MPFLR and more stable patellae in the augmentation group at each follow-up point. Functional evaluations at 2 and 5 years revealed statistically significant superior results in the augmentation group. Finally, no patient in the augmentation group and 2 (4.7%) in the nonaugmentation group experienced episodes of redislocation, and 1 patient (2.4%) in the augmentation group and 8 (18.6%) in the nonaugmentation group experienced multiple episodes of patellar instability, resulting in failure rates of 2.4% and 23.3% in the augmentation group and nonaugmentation group, respectively (P = .004).

CONCLUSION

Medial patellofemoral ligament reconstruction with polyester suture augmentation results in better static patellar position, dynamic stability, and functional outcome than without augmentation in the treatment of recurrent patellar dislocation in adults.

The role of medial retinaculum plication versus medial patellofemoral ligament reconstruction in combined procedures for recurrent patellar instability in adults

BACKGROUND

The comparative clinical outcome of medial retinaculum plication (MRP) versus medial patellofemoral ligament reconstruction (MPFLR) for recurrent patellar instability in adults is unknown.

HYPOTHESIS

Arthroscopic MRP can yield similar results to MPFLR for recurrent patellar instability in adults.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

One hundred patients with recurrent patellar instability were randomly divided into 2 groups receiving either arthroscopic MRP or MPFLR. Lateral release and anteromedial or distal tibial tubercle transfers were also performed as indicated. Follow-ups were performed at 12, 24, and 60 months postoperatively, and computed tomography (CT) was performed immediately after the operation and at follow-up. The passive patella glide test was performed before surgery and at each follow-up point. The degree of knee function was evaluated preoperatively and at 2 and 5 years postoperatively using the International Knee Documentation Committee (IKDC), Lysholm, and Kujala rating scales. Survival analysis was performed, and redislocation or multiple episodes of patellar instability were considered as indicating failure.

RESULTS

Forty-three patients in the MRP group and 45 patients in the MPFLR group were followed for 5 years and received complete evaluations. The correction of the static patellar position deteriorated over time in both groups, but significantly better results were observed for the MPFLR group. The results of the passive patella glide test indicated more stable patellae in the MPFLR group at each follow-up point. Functional evaluations at 2 and 5 years (final Lysholm score, 69.3 ± 6.9 vs 86.9 ± 6.1; Kujala score, 73.8 ± 5.5 vs 87.4 ± 5.7) revealed statistically significant superior results in the MPFLR group. Finally, 4 patients (9.3%) in the MRP group and 1 (2.2%) in the MPFLR group experienced episodes of redislocation, and 7 patients (16.3%) in the MRP group and 3 (6.7%) in the MPFLR group experienced multiple episodes of patellar instability (P = .037). Kaplan-Meier survival analysis and a log-rank test indicated better results and a significantly higher survival rate (P = .006) in the MPFLR group.

CONCLUSION

MPFLR results in better static patellar position and functional outcome than MRP in the treatment of recurrent patellar dislocation in adults.

Prediction of the graft size of 4-stranded semitendinosus tendon and 4-stranded gracilis tendon for anterior cruciate ligament reconstruction: a Chinese Han patient study

BACKGROUND

Little information is available regarding parameters that would enable a surgeon to predict the size and length of 4-stranded semitendinosus (ST) and 4-stranded gracilis tendon (GT) grafts.

PURPOSE

To evaluate whether certain preoperative anthropometric data enable prediction of the size of 4-stranded ST and GT autograft for anterior cruciate ligament (ACL) reconstruction.

STUDY DESIGN

Cohort study (prevalence); Level of evidence, 2.

METHODS

This study involved 235 Chinese Han patients who underwent double-bundle ACL reconstruction with 4-stranded autogenous ST and GT grafts. Preoperatively, the authors recorded height, weight, body mass index (BMI), gender, age, and sports activity. During surgery, the usable length of the ST and GT and the diameter of the 4-stranded grafts made of ST and GT were measured. Multiple regression analysis was used to determine relationships between anthropometric measurements and the length and diameter of intraoperatively measured ST and GT grafts.

RESULTS

Strongest correlations for ST and GT length and GT graft diameter were height and weight. The strongest correlations for ST graft diameter were gender and weight. Body mass index had only moderate correlations with ST and GT graft size. Self-reported activity level was not correlated. Women had significantly smaller GT and ST graft diameters and shorter tendon lengths than did men. Semitendinosus graft size was significantly larger and longer than was the GT graft (7.4 ± 0.7 mm vs 5.9 ± 0.6 mm and 279.9 ± 20.8 mm vs 251.5 ± 20.8 mm, respectively). Simple regression analysis demonstrated that height, weight, and BMI can be used to predict ST and GT autograft length and diameter.

CONCLUSION

Several preoperative anthropometric measurements showed correlation with the length of the ST and GT and diameter of 4-stranded ST and GT grafts. The current data may provide surgeons with important preoperative information about size of ST and GT grafts and would be useful for patient counseling and alternative graft source planning.

The biomechanical and clinical application of using the anterior half of the peroneus longus tendon as an autograft source

BACKGROUND

The shortage of autogenous grafts has often times been a problem in knee ligament reconstruction. There are little data concerning the use of the anterior half of the peroneus longus tendon (AHPLT) as an autograft.

HYPOTHESIS

The AHPLT is a suitable graft with respect to its strength, safety, and donor site morbidity.

STUDY DESIGN

Descriptive laboratory study and case series; Level of evidence, 4.

METHODS

The safety and efficacy of using the AHPLT as an autograft source were evaluated. A cadaveric study was first done to reveal the anatomic profile of the AHPLT, to test its failure load, and to compare it with that of the semitendinosus and gracilis tendons. Then, a cadaveric harvest study was performed to show it was safe and reproducible. The space between the tendon stripper and the peroneal nerve during harvesting of the AHPLT was evaluated. Lastly, a clinical study was performed to evaluate donor site morbidity. The preoperative and postoperative foot and ankle functions of 92 patients who underwent a variety of knee ligament reconstructions with the AHPLT were followed for more than 2 years and were then evaluated using the American Orthopedic Foot and Ankle Society (AOFAS) scale and the Foot and Ankle Disability Index (FADI) to determine the influence of tendon removal on ankle and foot function.

RESULTS

The average failure load of the AHPLT was 322.35 ± 63.18 N, accounting for 97.69% ± 19.48% and 147.94% ± 41.30% of the semitendinosus and gracilis tendons, respectively. During tendon harvesting, the distance between the head of the tendon stripper and the branching point of the deep peroneus nerve was 4.6 to 10.4 cm. The clinical study showed that the preoperative and postoperative AOFAS scores were 97.4 ± 2.0 and 97.2 ± 1.6 (P = .85), respectively, while the FADI scores preoperatively and postoperatively were 96.8 ± 2.2 and 96.9 ± 2.5 (P = .91), respectively. No signs of peroneus nerve injury, peroneus longus tendon rupture, or tendinopathy were found.

CONCLUSION

The AHPLT is acceptable for use as an autograft with respect to its strength, safety, and donor site morbidity.

Recurrent patellar dislocation in adolescents: medial retinaculum plication versus vastus medialis plasty

BACKGROUND

The clinical outcome of arthroscopic medial retinaculum plication (MRP) compared with vastus medialis plasty (VMP) for recurrent patellar dislocation in adolescents is unknown.

HYPOTHESIS

Arthroscopic MRP can yield similar results to open VMP for recurrent patellar dislocation in adolescents.

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 2.

METHODS

Sixty adolescent patients were randomly divided into 2 groups to receive arthroscopic MRP and open VMP respectively. The patients were followed up at 3, 6, 12, and 24 months postoperatively and computed tomography (CT) scans were taken immediately after operation and at 12 and 24 months postoperatively to evaluate the position of the patella. Knee function was evaluated at 24 months postoperatively according to the International Knee Documentation Committee (IKDC), Kujala, Lysholm, and Tegner rating scales. For those who underwent operation more than 3 years previously, an additional review was taken to evaluate the latest patellar stability status.

RESULTS

The final follow-up time was 56.8 ± 21.5 months (range, 24-92 months) and 59.1 ± 24.7 months (range, 24-88 months), respectively, in the MRP and VMP groups. The CT examination showed that the correction of the patellar position deteriorated over time in both groups. The final patellar position was significantly better than that before surgery in the VMP group, but not in the MRP group. The VMP group had significantly better clinical results at each follow-up compared with the MRP group. The IKDC, Lysholm, Kujala, and Tegner scores were 62.5 ± 6.2, 70.7 ± 5.1, 76.6 ± 4.8, and 3.9 ± 0.7, respectively, in the MRP group, and 71.8 ± 7.1 (P < .001), 79.4 ± 5.5 (P < .001), 82.9 ± 4.8 (P < .001), and 5.1 ± 1.4 (P < .001), respectively, in the VMP group at the 2-year follow-up. Five patients (17.9%) in the MRP group and 2 patients (7.7%) in the VMP group (P = .267) experienced episodes of redislocation at the final follow-up.

CONCLUSION

Arthroscopic MRP is less reliable for maintaining the corrected position of the patella and for functional recovery compared with VMP for recurrent patellar dislocation in adolescents.

Arbitrary starting point of separation affects morphology of the 2 bundles of anterior cruciate ligament at insertion sites

PURPOSE

To explore whether changes in the starting point of separation affect the morphology of the 2 bundles of the anterior cruciate ligament (ACL) at insertion.

METHODS

Ten cadaveric knees were used to separate the ACL fibers into 2 bundles from 3 different starting points that were located at the proximal one fifth, two fifths, and three fifths of the inter-bundle mark line. The dividing lines between the 2 bundles at insertion and the area of the anteromedial (AM) bundle resulting from these different separations were compared, with data collected in groups I, II, and III, respectively.

RESULTS

The angle of the dividing line and the long axis of the femoral footprint was 67.24 degrees +/- 11.94 degrees, 91.01 degrees +/- 11.16 degrees, and 116.03 degrees +/- 9.01 degrees in groups I, II, and III, respectively, and the percentage of the AM bundle area in the whole femoral footprint was 38.64% +/- 5.55%, 52.22% +/- 6.76%, and 65.09% +/- 4.53%, respectively. At the tibial insertion sites, the angle between the dividing line and the sagittal plane was 110.17 degrees +/- 13.26 degrees, 127.72 degrees +/- 8.94 degrees, and 149.28 degrees +/- 18.80 degrees in groups I, II, and III, respectively, and the percentage of the AM bundle area in the whole footprint was 25.72% +/- 3.82%, 40.41% +/- 3.73%, and 60.56% +/- 6.59%, respectively. There were statistical differences between the angle and the area data of each of the 2 groups at either the tibial or femoral insertion site.

CONCLUSIONS

In an anatomic study of the ACL, changes in the point from which separation started resulted in noticeably different bundle morphology at the insertion.

CLINICAL RELEVANCE

Proper separation will lead to a more accurate bundle description and, thus, a more accurate location of the tunnels in ACL reconstruction.

[Primary clinical results of double-bundle anterior cruciate ligament reconstruction with semitendinosus allografts]

OBJECTIVE

To evaluate the primary clinical results of double-bundle anterior cruciate ligament reconstruction (ACLR) with semitendinosus allografts.

METHODS

From March 2006 to October 2006, 33 patients underwent double-bundle ACLR with semitendinosus allografts. The complete followed-up data of 31 patients was analyzed retrospectively. There were 24 males and 7 females aged 18-35 years old (average 25 years old). The injury was caused by sports accidents in 23 cases and traffic accidents in 8 cases, involving the left knee in 18 cases and the right knee in 13 cases. Anterior cruciate ligament rupture were confirmed by MRI and arthroscopy in all the patients, without lateral collateral ligaments injuries and posterior cruciate ligament injuries. The time from injury to operation was 1-43 months (average 11 months). The knee was fixed at 0 degree position after operation for 2 weeks and got knee joint rehabilitation exercises gradually.

RESULTS

The incision of 2 patients showed effusion 4 and 7 days after operation, respectively, and healed after symptomatic treatment. The incision of 29 patients healed by first intention. There were no complications such as stiffness of knee joint, neurovascular injuries and joint infections. All the patients were followed up for 24-29 months (average 26 months). MRI displayed the anterior cruciate ligament grafts presented with good connection and signal similar to the normal 2 years after operation. There was significant difference between the preoperational value and the final follow-up value in terms of bilateral knee joint difference of prior laxity, Lachman test, and pivot shift test (P < 0.05 ). The circumference difference between the injured and the normal was (11.6 +/- 7.9) mm before operation and (5.0 +/- 3.1) mm at the final follow-up (P < 0.05). The Tegner score, Lysholm score, and International Knee Documentation Committee score was 3.83 +/- 1.15, 64.38 +/- 6.81, and 41.42 +/- 6.30, respectively, before operation, and 6.29 +/- 0.64, 94.45 +/- 3.03, and 95.72 +/- 3.10, respectively, at the final follow-up. There was a significant difference between before and after operation (P < 0.05).

CONCLUSION

The primary clinical results of double-bundle ACLR with semitendinosus allografts are satisfactory and the allogeneic semitendinosus are good grafts for double-bundle ACLR.

Risk factors for articular cartilage lesions in symptomatic discoid lateral meniscus

PURPOSE

To investigate risk factors related to articular cartilage lesions in discoid lateral meniscus (DLM) and to analyze the possible mechanisms associated with articular cartilage lesions.

METHODS

From October 2004 to April 2008, 103 knees in 97 patients with DLM confirmed by arthroscopy were operated on at our clinical center. Among them, 16 knees were accompanied by articular cartilage injury. Data on risk factors, including patient age, traumatic history, DLM type, presence or absence of tear, symptomatic duration, and meniscal shape, were analyzed to investigate the relation with articular cartilage lesion by logistic regression analysis.

RESULTS

Only symptomatic duration and meniscal shape had a significant relation with articular cartilage lesion. Symptomatic duration and meniscal shape can be regarded as risk factors, and their odds ratios were 4.983 (P < .01) and 5.356 (P < .05), respectively.

CONCLUSIONS

Long symptomatic duration (>6 months) and asymmetrical shape of DLM were more frequently related to articular cartilage lesions than other factors.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

[Biomechanical research of reconstructing anterior cruciate ligament by implanting various length of autogenous tendon into bone tunnel]

OBJECTIVE

To make a comparison for the change of maximum tensile intensity and stiffness of a whole implant that is placed into bone tunnel with various lengths tendon, by using beagle dog's autogenous flexor tendons to reconstruct anterior cruciate ligament (ACL).

METHODS

Sixty male beagle dogs were included in the experiment (weighting 13-16 kg). Three dogs were used for intact flexor tendon of both knees (normal control group), 3 dogs for the intact ACL and femur-graft-tibia complex (auto control group) and 54 dogs (108 knees) for models of reconstructed ACL (6 experimental groups according to different lengths of tendon: 5, 9, 13, 17, 21 and 25 mm in the bone tunnel). The tensile intensity and stiffness were measured after 45, 90 and 180 days separately after operation.

RESULTS

In the normal control group, the maximum tensile intensity of the intact flexor tendon was (564.15 +/- 36.18) N, the stiffness was (59.89 +/- 4.28) N/ mm. In the auto control group, the maximum tensile intensity of the intact ACL was (684.75 +/- 48.10) N, the stiffness was (74.34 +/- 6.99) N/ mm, all ruptured through the intra-articular portion of the graft. The maximum tensile intensity of femur-graft-tibia complex in the auto control group was (301.92 +/- 15.04) N, the stiffness was (31.35 +/- 1.97) N/mm. After 45 days of operation, all failure occurred at the tibial or femoral insertion site. After 90 days of operation, 24 of the breakpoints were scattered in tendon-bone junction, 12 (3 in 17 mm group, 5 in 21 mm group, 4 in 25 mm group) ruptured through the intra-articular portion. After 180 days of the operation, all breakpoints were distributed inside joint of the implant. The maximum tensile intensity and the stiffness were stronger in 17, 21 and 25 mm groups than in 5, 9 and 13 mm groups after operation (P < 0.05).

CONCLUSION

Tendon with 17 mm length, which will be implanted into bone tunnel, is an applicable index, in reconstruction of ACL by autogenous tendons.

Simultaneous double-bundle anterior cruciate ligament and posterior cruciate ligament reconstruction with autogenous hamstring tendons

PURPOSE

The purpose of this study was to evaluate the clinical results of simultaneous double-bundle anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) reconstruction.

METHODS

We performed arthroscopic reconstruction in 21 cases of combined ACL/PCL rupture, 14 chronic and 7 acute, with autogenous hamstring tendons in 1 stage, both in a double-bundle and 4-tunnel manner. The semitendinosus tendon and gracilis tendon from the uninjured leg were used to make two 4-stranded grafts to reconstruct the PCL, and those from the injured leg were used to make two 4-stranded grafts to reconstruct the ACL. The grafts were suspended with a mini-plate and buttons. The patients were followed up for a minimum of 2 years and evaluated according to the International Knee Documentation Committee (IKDC) and Lysholm rating scale. The anterior-posterior knee laxity was assessed by KT-1000 examination (MEDmetric, San Diego, CA).

RESULTS

At the last follow-up, all patients showed normal knee extension. One patient had a 10 degrees flexion limitation, and four had a 5 degrees flexion limitation. KT-1000 examination showed that the side-to-side difference in overall anterior-posterior laxity at 70 degrees flexion was 0 to 2 mm in 16 patients, 3 to 5 mm in 4 patients, and 6 to 10 mm in 1 patient; the side-to-side difference in overall anterior-posterior laxity at 25 degrees flexion was 0 to 2 mm in 14 patients, 3 to 5 mm in 6 patients, and 6 to 10 mm in 1 patient. The IKDC subjective, Lysholm, and Tegner scores were 85.5 +/- 5.8, 91.9 +/- 4.2, and 5.0 +/- 1.9, respectively. According to the last IKDC evaluation, the results were graded as normal in 13 patients (61.9%), nearly normal in 7 patients (33.3%), and abnormal in 1 patient (4.8%).

CONCLUSIONS

Simultaneous double-bundle ACL and PCL reconstruction with autogenous hamstring tendons can yield normal results in 61.9% of patients and nearly normal results in 33.3% at a minimum of 2 years.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Tendon-bone healing enhancement using injectable tricalcium phosphate in a dog anterior cruciate ligament reconstruction model

PURPOSE

The purpose of this study was to evaluate the enhancement potential of injectable tricalcium phosphate (TCP) for tendon-bone healing in anterior cruciate ligament (ACL) reconstruction in a dog model.

METHODS

In this experimental study ACL reconstruction was performed on both knees of 48 beagle dogs with the tendon of the flexor digitorum longus. A suspension fixation technique was used, and the tendon graft filled only the tunnel parts near the joint. On the experimental side, in addition to ACL reconstruction, injectable TCP was used to fill those tunnel parts that were not filled by the graft. On the other side, no additional treatment was applied (control). At 2, 4, 6, 8, 10, and 12 weeks postoperatively, 8 dogs were killed, respectively, with 3 for histologic observation at the proximal tendon-bone junction and 5 for mechanical examination.

RESULTS

Histologic observation showed that on the experimental side, Sharpey fibers, fibrocartilage, and calcified cartilage appear earlier at the tendon-bone interface and tendon-bone healing proceeded more quickly than on the control side. Mechanical examination showed that within 4 weeks, the pullout strength was higher on the experimental side than on the control side, and there was a statistically significant difference between the results.

CONCLUSIONS

Filling the bone tunnel with TCP after inserting the ACL graft results in faster incorporation of the graft to the tunnel, with better biomechanical properties and a more mature histologic pattern.

CLINICAL RELEVANCE

If these results are clinically applicable, rapid tendon-bone healing may be expected in ACL reconstruction.

Arthroscopic treatment of nonunited anterior cruciate ligament tibial avulsion fracture with figure-of-8 suture fixation technique

PURPOSE

The purpose of this study was to evaluate the clinical results of arthroscopic treatment of nonunited anterior cruciate ligament (ACL) tibial avulsion fracture with a figure-of-8 suture fixation technique.

METHODS

Nineteen cases of nonunited ACL tibial avulsion fracture were treated with an arthroscopic figure-of-8 suture fixation technique. The patients were followed up and evaluated according to the International Knee Documentation Committee, Lysholm, and Tegner rating scales.

RESULTS

The time interval between the previous injury and this operation was 1 to 8 years, with a mean of 3.6 years. Eighteen patients were followed up for more than 2 years (range, 24 to 30 months; mean, 26 months). The fracture was united within 3 months after surgery in all cases. At the latest follow-up, there was neither extension nor flexion limitation in all patients. With the exception of 1 patient who had a 1 degrees positive Lachman test with a firm end-point, all of the patients had a negative Lachman test. The side-to-side difference in knee anterior laxity was 0 to 2 mm in 17 patients and 4 mm in 1 patient. The Lysholm score was 91 to 100, with a mean of 96.7 +/- 1.9 (compared with 74.3 +/- 4.6 before surgery, P < .05). Fifteen patients returned to their former activity level. The Tegner scores before injury, preoperatively, and at latest follow-up were 6.1 +/- 0.6, 3.6 +/- 1.0, and 6.0 +/- 0.8, respectively; there was no statistically significant difference between the preinjury and postoperative Tegner scores (P > .05). According to the International Knee Documentation Committee scale, 17 patients' knees were graded as normal and 1 patient's knee was nearly normal.

CONCLUSIONS

Arthroscopic treatment of nonunited ACL tibial avulsion fracture with a figure-of-8 suture fixation technique can ensure fracture healing and restore the stability and function of the joint in most patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

[Development of the meniscal replacement in clinical practice]

OBJECTIVE

To review the details of the current efforts to reconstruct or replace the meniscus.

METHODS

Three kinds of procedures of reconstructing or replacing the meniscus were analyzed and evaluated by an extensive review of the latest literatures concerned.

RESULTS

Three kinds of techniques were established to reconstruct the meniscus clinically, i.e., the allograft of the meniscus, meniscal reconstruction with the autotendon, and the meniscus scaffold. There were still a few defects in the meniscal replacement, and so the curative techniques would still be investigated.

CONCLUSION

Many efforts have been made to reconstruct the meniscus after its injury or its resection so as to prevent degeneration of the knee joint. The meniscal replacement has been employed for many years, but it has not worked so well. The establishment of an ideal replacement of the meniscus requires further studies. Therefore, reconstruction of the meniscus function is still a challenging problem to the surgeons concerned.