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Total hip arthroplasty (THA) after rotational acetabular osteotomy (RAO) is technically demanding because of the characteristic acetabular morphology after RAO. The present study aimed to investigate the differences in the three-dimensional cup position between THA after RAO and primary THA. We analysed the pre-operative and post-operative computed tomography (CT) data of 120 patients (20 patients after RAO and 100 patients without a history of RAO) who underwent THA between January 2017 and June 2018. We evaluated radiographic parameters, including acetabular anteversion, antero-posterior distance at the level of the femoral head centre, the presence of anterior acetabular osteophyte and/or rotated fragment during RAO from the CT data. Additionally, operative data and clinical scores were also evaluated. Although we found no significant differences in any clinical parameters, there were significant differences in radiographic parameters and operative data. The morphology of the acetabulum was significantly retroverted, and the antero-posterior distance was longer in patients after RAO, compared to the implanted cup. Additionally, longer operative time was necessary for such patients. These results reflect the atypical acetabular morphology after RAO, and emphasize that care should be taken to avoid anterior bony impingement and post-operative dislocation. For cup implantation during THA after RAO, surgeons should acknowledge the atypical morphology of the acetabulum and not be misled by its visual shape.

Ectopic endochondral ossification in the tendon/ligament is caused by repetitive mechanical overload or inflammation. Tendon stem/progenitor cells (TSPCs) contribute to tissue repair, and some express lubricin [proteoglycan 4 (PRG4)]. However, the mechanisms of ectopic ossification and association of TSPCs are not yet known. Here, we investigated the characteristics of Prg4-positive ( + ) cells and identified that R-spondin 2 (RSPO2), a WNT activator, is specifically expressed in a distinct Prg4 + TSPC cluster. The Rspo2 + cluster was characterized as mostly undifferentiated, and RSPO2 overexpression suppressed ectopic ossification in a mouse Achilles tendon puncture model via chondrogenic differentiation suppression. RSPO2 expression levels in patients with ossification of the posterior longitudinal ligament were lower than those in spondylosis patients, and RSPO2 protein suppressed chondrogenic differentiation of human ligament cells. RSPO2 was induced by inflammatory stimulation and mechanical loading via nuclear factor κB. Rspo2 + cells may contribute to tendon/ligament homeostasis under pathogenic conditions.

The Runt-related transcription factor (Runx) family plays various roles in the homeostasis of cartilage. Here, we examined the role of Runx2 and Runx3 for osteoarthritis (OA) development in vivo and in vitro. Runx3 knockout mice accelerated OA by surgical induction, accompanied with decreased expression of lubricin and aggrecan. Meanwhile, Runx2 conditional knockout mice showed biphasic phenotypes; OA was inhibited by hetero-knockout accompanied with decreased matrix metallopeptidase 13 (Mmp13) expression, but accelerated in homo-knockout of Runx2 accompanied with reduction of type II collagen (Col2a1) expression. Comprehensive transcriptional analyses revealed lubricin and aggrecan as transcriptional target genes of Runx3, and indicated that Runx2 sustained Col2a1 expression through an intron 6 enhancer when Sox9 was decreased. Intra-articular administration of Runx3 adenovirus ameliorated development of surgically induced OA. Runx3 protects adult articular cartilage through extracellular matrix protein production under the normal condition, while Runx2 exerts both catabolic and anabolic effects under the inflammatory condition.

Somatic stem cell transplantation has been performed for cartilage injury, but the reparative mechanisms are still conflicting. The chondrogenic potential of stem cells are thought as promising features for cartilage therapy; however, the correlation between their potential for chondrogenesis in vitro and in vivo remains undefined. The purpose of this study was to investigate the intrinsic chondrogenic condition depends on cell types and explore an indicator to select useful stem cells for cartilage regeneration.The chondrogenic potential of two different stem cell types derived from adipose tissue (ASCs) and synovium (SSCs) of mice and humans was assessed using bone morphogenic protein-2 (BMP2) and transforming growth factor-β1 (TGFβ1). Their in vivo chondrogenic potential was validated through transplantation into a mouse osteochondral defect model.All cell types showed apparent chondrogenesis under the combination of BMP2 and TGFβ1 in vitro, as assessed by the formation of proteoglycan- and type 2 collagen (COL2)-rich tissues. However, our results vastly differed with those observed following single stimulation among species and cell types; apparent chondrogenesis of mouse SSCs was observed with supplementation of BMP2 or TGFβ1, whereas chondrogenesis of mouse ASCs and human SSCs was observed with supplementation of BMP2 not TGFβ1. Human ASCs showed no obvious chondrogenesis following single stimulation. Mouse SSCs showed the formation of hyaline-like cartilage which had less fibrous components (COL1/3) with supplementation of TGFβ1. However, human cells developed COL1/3+ tissues with all treatments. Transcriptomic analysis for TGFβ receptors and ligands of cells prior to chondrogenic induction did not indicate their distinct reactivity to the TGFβ1 or BMP2. In the transplanted site in vivo, mouse SSCs formed hyaline-like cartilage (proteoglycan+/COL2+/COL1-/COL3-) but other cell types mainly formed COL1/3-positive fibrous tissues in line with in vitro reactivity to TGFβ1.Optimal chondrogenic factors driving chondrogenesis from somatic stem cells are intrinsically distinct among cell types and species. Among them, the response to TGFβ1 may possibly represent the fate of stem cells when locally transplanted into cartilage defects.

Background Somatic stem cell transplantation has been performed for cartilage injury, but the reparative mechanisms are still conflicting. The chondrogenic potential of stem cells are thought as promising features for cartilage therapy; however, the correlation between their potential for chondrogenesis in vitro and in vivo remains undefined. The purpose of this study was to investigate the intrinsic chondrogenic condition depends on cell types and explore an indicator to select useful stem cells for cartilage regeneration. Methods The chondrogenic potential of two different stem cell types derived from adipose tissue (ASCs) and synovium (SSCs) of mice and humans was assessed using bone morphogenic protein-2 (BMP2) and transforming growth factor-β1 (TGFβ1). Their in vivo chondrogenic potential was validated through transplantation into a mouse osteochondral defect model. Results All cell types showed apparent chondrogenesis under the combination of BMP2 and TGFβ1 in vitro, as assessed by the formation of proteoglycan- and type 2 collagen (COL2)-rich tissues. However, our results vastly differed with those observed following single stimulation among species and cell types; apparent chondrogenesis of mouse SSCs was observed with supplementation of BMP2 or TGFβ1, whereas chondrogenesis of mouse ASCs and human SSCs was observed with supplementation of BMP2 not TGFβ1. Human ASCs showed no obvious chondrogenesis following single stimulation. Mouse SSCs showed the formation of hyaline-like cartilage which had less fibrous components (COL1/3) with supplementation of TGFβ1. However, human cells developed COL1/3+ tissues with all treatments. Transcriptomic analysis for TGFβ receptors and ligands of cells prior to chondrogenic induction did not indicate their distinct reactivity to the TGFβ1 or BMP2. In the transplanted site in vivo, mouse SSCs formed hyaline-like cartilage (proteoglycan+/COL2+/COL1−/COL3−) but other cell types mainly formed COL1/3-positive fibrous tissues in line with in vitro reactivity to TGFβ1. Conclusion Optimal chondrogenic factors driving chondrogenesis from somatic stem cells are intrinsically distinct among cell types and species. Among them, the response to TGFβ1 may possibly represent the fate of stem cells when locally transplanted into cartilage defects.

Background Hip arthroplasty using acrylic prosthesis was once conducted; however, it has now been abandoned because of early breakages and wear of material. Therefore, complications or revision surgeries due to the use of acrylic prostheses are becoming rare. Case presentation A 76-year-old woman presented with a sudden onset of severe pain in her left femur while walking. Radiographs revealed severe osteolysis and periprosthetic femoral fracture 45 years after the initial hemiarthroplasty using an acrylic prosthesis. We performed a Girdlestone resection arthroplasty by removing the prosthesis and fixing the fracture site using an intramedullary nail and metal plate. The patient was pain-free in her hip and leg 2 years and 9 months after the surgery. Although she walked with a cane or crutches, no postoperative complications were observed. Conclusions The combined use of an intramedullary nail and plate fixation with resection arthroplasty could offer acceptable results for patients with severe osteolysis and periprosthetic fracture after femoral head replacement using an acrylic prosthesis. Our report seems relevant because it not only reminds us of the significant steps made in the development of modern total hip arthroplasty; it also highlights one of the surgical options for severe osteolysis and periprosthetic fracture of the hip.

Background: Somatic stem cell transplantation has been performed for cartilage injury, but the reparative mechanisms are still conflicting. The chondrogenic potential of stem cells are thought as promising features for cartilage therapy, however the correlation between their potential for chondrogenesis in vitro and in vivo remains undefined. The purpose of this study was to investigate the intrinsic chondrogenic condition depends on cell types and explore an indicator to select useful stem cells for cartilage regeneration.Methods: The chondrogenic potential of two different stem cell types derived from adipose tissue (ASCs) and synovium (SSCs) of mice and humans was assessed using bone morphogenic protein-2 (BMP2) and transforming growth factor-β1 (TGFβ1). Their reparative potential was also validated through transplantation into a mouse osteochondral defect model.Results: All cell types showed apparent chondrogenesis under the combination of BMP2 and TGFβ1 in vitro, as assessed by the formation of proteoglycan- and type 2 collagen (COL2)-rich tissues. However, our results vastly differed with those observed following single stimulation among species and cell types; apparent chondrogenesis of mouse ASCs, mouse SSCs, and human SSCs was observed with supplementation of BMP2, either BMP2 and TGFβ1, and BMP2, respectively. Human ASCs showed no chondrogenesis following single stimulation. Among human SSCs, two of six donors formed partially COL2-positive tissues in response to TGFβ1. However, unlike mouse cells, human cells showed fibrous components (COL1/3) with all treatments. Mouse SSCs formed hyaline-like cartilage (proteoglycan+/COL2+/COL1-/COL3-) in the transplanted site in vivo, but other cell types mainly formed COL1/3-positive fibrous tissues. Remarkably, only donors that showed chondrogenic response to TGFβ1 in vitro formed partially COL2-positive tissues in vivo. However, the area was mainly composed of COL1/3, indicating fibrous cartilage-like tissues.Conclusion: The chondrogenic response to TGFβ1 may represent the fate of stem cells when locally transplanted into cartilage defects.

Background Fatty infiltration of the gluteus muscles increases due to the presence of hip osteoarthritis (OA); it is often evident in the gluteus minimus. The gluteus minimus acts not only as an abductor and rotator but also helps stabilize the femur's head. Moreover, the atrophy or fatty infiltration of the gluteus minimus leads to an increased risk of fall and fracture. Until now, fatty infiltration of this muscle has often been evaluated using magnetic resonance imaging using the Goutallier classification system, originally developed for the rotator cuff. However, the accessibility of magnetic resonance imaging remains problematic, and the reliability of the classification has room for improvement. Thus, this study aimed to devise a new classification system for the fatty infiltration of the gluteus minimus using plain computed tomography (CT). Methods We retrospectively reviewed 71 patients (141 hips) who underwent unilateral total hip arthroplasty for hip OA. To assess the system's reliability, three doctors classified the fatty infiltration of the gluteus minimus based on the CT images of 20 hips randomly selected from the study participants using both the Goutallier and the new classification systems. Then, we selected 113 hips with Crowe type 1 and evaluated them using the new classification system to assess the association between the extent of fatty infiltration and the severity of hip OA. Results Both classifications had good intra- and inter-observer reliability. The kappa values of the new classification system (0.83–0.95) were higher than that of the Goutallier classification system (0.72–0.87). The Jonckheere–Terpstra test showed that the degree of fatty infiltration of the gluteus minimus according to the new system progressed incrementally with the progression of hip OA (p = 0.016). Conclusions The new classification system can be recommended for clinical use.

Additional file 5. Gene expression of chondrogenic marker in the mASCs and mSSCs cultured with BMP2, TGFβ1, or their combination at day 14. Data are collected from over three independent lots and presented as a box plot with dot plot.

Additional file 7. Extended data in mouse SSCs transplantation group without in vivo chondrogenesis. (A) In samples which defect site is close to enthesis, host synovial tissue infiltrated to defect site and inhibited in vivo chondrogenesis, but transplanted mSSCs existed within granulation tissue with unspecified state. (B) Synovial infusions must be observed in samples with patellar dislocation. Notably, IHC for GFP implies vessel like structure built by transplanted mSSCs. (C) In the samples with in vivo chondrogenesis, transplanted mSSCs existed with unspecified state in bone marrow region underneath neo cartilage.

Additional file 20. Micro-CT and histological images in the samples transplanted with hSSCs. IHC images for COL2 with red frame have the area positively stained, and images with blue frame were except for quantification because of non-specific staining. IHC images for SOX9 with yellow frame represents the presence of SOX9 positive cells.

Additional file 8. Saf-O and IHC for pSmad1 and pSmad2 of in vivo specimens of transplanted with mSSCs or mASCs. Representative data are shown. Scale bars = 100 μm.

Additional file 14. Pearson correlation analysis between measurements of histological images in chondrogenic pellet cultured with BMP2, TGFβ1, and their combination. (A) Correlation between proteoglycan and COL2 of hSSCs. (B,C) Correlation between fibrous marker and COL2 of hASCs. Each circle represents individual six donors, and circle size reflects standard deviation for the data plotted in Y axis.

Additional file 4. Chondrogenic pellet culture of mASCs and mSSCs in chondrogenic basal media at day 14. Representative data of macroscopic images and histology are shown.

Additional file 6. Histological features for fibrous cartilage or ectopic cartilage development after transplantation with mouse ASCs.

Additional file 9. The alteration of gene expression of TGFβ superfamily receptors (A), ligands, and chondrogenic markers (B) during chondrogenic culture of mSSCs and mASCs. Data are expressed as Mean ± SD for each lot, and each shape of points represent individual lots.

Background: Precise acetabular cup placement is essential for successful total hip arthroplasty (THA). In obese patients, its accuracy is often difficult to achieve because of the thickness of the soft tissues. This study aimed to determine the relationship between the accuracy of acetabular cup angle and body mass index (BMI) in posterolateral THA using the computed tomography-based navigation (CT-navi) system.Methods: We retrospectively reviewed 145 consecutive primary THAs using the CT-navi system between January 2015 and January 2018. All surgeries were performed using cementless cups employing the posterolateral approach with the patient in the decubitus position. We compared the radiographic inclination and anteversion obtained from the angle displayed on the CT-navi screen with those measured by the postoperative CT using the three-dimensional templating software. We evaluated the relationship between the extent of errors and correlation with BMI. Statistical analyses were performed using the Student’s t-test and Spearman’s rank coefficient test.Results: In non-overweight patients (BMI < 25, 88 hips), the mean navigation errors for inclination were 2.8 ± 2.2° and for anteversion were 2.6 ± 2.3°. Meanwhile, in overweight patients (BMI ≥ 25, 57 hips), the mean navigation errors were 2.6 ± 2.4° for inclination and 2.4 ± 2.4° for anteversion. We found no significant difference between overweight and non-overweight patients in both inclination and anteversion. The Spearman’s rank correlation coefficients were -0.04 for inclination and -0.11 for anteversion, showing no correlation between the extent of errors and BMI.Conclusions: In posterolateral THA, CT-navi can aid the precise placement of the acetabular cup irrespective of a patient’s BMI.Trial registration: This trial was retrospectively registered and approved by the institutional ethics committee of Teikyo University. The registration number is 17-190, and the date of approval was March 1, 2018. URL of trial registry is: https://www.teikyo-u.ac.jp/application/files/7015/8432/1341/2016_all_syounin_1.pdf

Purpose:The results of reamed bipolar hemiarthroplasty (BHA) in patients with hip osteoarthritis (OA) are reported to be unfavorable. Acetabular reaming for sufficient bony coverage caused bipolar head migration into the superomedial direction, and most patients required revision surgeries. Several methods are applicable to treat decreased bone stock. This study aimed to investigate the midterm results of revision surgeries using the cementless cup with the rim-fit technique.Methods:Between 1996 and 2014, acetabular revision surgeries using the cementless cup with the rim-fit technique were performed in 86 hips (74 patients). We evaluated radiographic outcomes, including positional change of the rotation center of the artificial femoral head, presence of implant loosening, and filling of the initial gap. We also evaluated clinical outcomes, including the Harris hip score (HHS), and postoperative complications.Results:The average positional changes from BHA to prerevision surgeries were 8.0 mm superiorly and 4.1 mm medially. The average changes from prerevision to postrevision surgeries were 3.7 mm inferiorly and 2.4 mm laterally. No implant loosening was found in all cases; the initial gap between the acetabular host bone and the acetabular cup was filled in 53 (93%) among 57 hips. The average HHS improved from 65.9 before revision surgeries to 83.8 in the latest follow-up. Dislocation and postoperative periprosthetic fracture occurred in two and five hips, respectively; no cases required rerevision surgeries.Conclusion:There were favorable midterm results of the revision total hip arthroplasty for migrated BHA in patients with hip OA using cementless cup with the rim-fit technique.

BackgroundRotational acetabular osteotomy (RAO) is a type of pelvic osteotomy performed to improve the acetabular bony coverage against the femoral head for patients with acetabular dysplasia. The acetabular bony coverage is ideally evaluated three-dimensionally; however, there is a paucity of published data regarding three-dimensional morphology in patients with long-term excellent outcome after RAO. The present study investigated the characteristics of three-dimensional acetabular morphology with long-term excellent outcome after RAO in comparison to patients with normal hip joints and those converted to total hip arthroplasty (THA) after RAO because of osteoarthritis (OA) progression.MethodsAnteroposterior plain radiograph and computed tomography data of 57 hip joints (17 joints with excellent outcome 20 years or more after RAO, 16 normal joints, and 20 joints converted to THA after RAO) were analyzed. The two-dimensional lateral center-edge (CE) angle from plain radiographs and acetabular anteversion, anterior acetabular sector angle, and posterior sector angle from computed tomography (CT) images were calculated.ResultsCompared with patients converted to THA, all parameters in patients with long-term excellent outcome after RAO were similar to those in patients with normal hip joints, particularly in the three-dimensional analyses. The anterior bony coverage was excessive, whereas the posterior bony coverage was deficient in patients converted to THA after RAO. Anterior bony impingement and posterior instability may be the cause of OA progression after RAO.ConclusionCaution must be taken to avoid rotating the separated fragment excessively to the anterior direction during RAO to prevent OA progression and achieve long-term excellent outcome.

Interpretation of thoracic spine radiographs is difficult because they cannot clearly depict the vertebrae due to overlap with soft tissues. This study aimed to evaluate whether thoracic spine radiographs obtained using the energy subtraction method could improve the accuracy of a diagnosis of thoracic osteolytic lesions. The authors analyzed 300 thoracic vertebrae from 25 patients with multiple myeloma who underwent thoracic spine radiography. All patients underwent thoracic spine radiography with 2 views. Two sets of images were prepared: computed radiography images (CR images) acquired using conventional processing parameters; and processed images for specifically visualizing bone, using the energy subtraction method (ES images). The CR images (CR group) and paired CR and ES images (CR+ES group) were interpreted in parallel by 5 orthopedic surgeons. The presence of osteolytic lesions was evaluated for each of the 12 thoracic vertebrae, and the sensitivity and specificity of the method were compared with computed tomography (CT), which is considered the gold standard. Subgroup analysis was also performed based on location. Osteolytic lesions were found on CT in 28 (9.3%) vertebrae of 12 patients. The overall sensitivities and specificities of the CR and CR+ES groups were 17.2% and 54.3%, respectively, and 95.6% and 98.0%, respectively, with statistically significant differences. Subgroup analysis showed particular improvement in the sensitivity for the CR+ES group in the middle thoracic spine compared with that at other locations. Thoracic spine radiographs generated using this method may improve the accuracy of diagnosis of thoracic osteolytic lesions. [ Orthopedics . 2021;44(1):e31–e35.]

Although laboratory tests and mid-term clinical outcomes show the clinical safety and remarkable wear resistance of the highly cross-linked polyethylene (HXLPE) acetabular liner with a nanometer-scaled graft layer of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), the wear resistance of the layer under severe abrasive conditions is concerning. We evaluated the effects of a roughened femoral head and the grafting locus on the wear resistance of the PMPC-grafted HXLPE liner and the effect of PMPC grafting on wear resistance of the HXLPE substrate by removing the PMPC-grafted layer using a severely roughened femoral head. Against a moderately roughened femoral head, the PMPC-grafted HXLPE liner showed negative wear, although an untreated HXLPE liner increased the wear by 154.1% compared with wear against a polished femoral head, confirming that PMPC grafts were unaffected. Against a severely roughened femoral head, the PMPC-grafted layer of the head contact area might be removed under severe conditions. However, the wear rate was reduced by 52.5% compared to that of untreated HXLPE liners. Moreover, the head non-contact area-modified PMPC-grafted HXLPE liner against a polished femoral head reduced the wear by 76.8% compared with untreated HXLPE liner; thus, this area may be also important in the development of fluid-film lubrication. STATEMENT OF SIGNIFICANCE: Here we describe effects of a roughened femoral head and the locus of grafting on the wear-resistance of the phospholipid polymer grafted highly cross-linked polyethylene (PMPC-HXLPE) liner. Against a moderately roughened femoral head, the PMPC-HXLPE liner showed negative wear, confirming that PMPC grafts were unaffected. After removing the PMPC layer of the head contact area using a severely roughened femoral head, the wear rate not only exceeded that of untreated HXLPE liners, but was reduced by 52.5%, confirming that PMPC grafting does not affect the wear-resistance of the HXLPE substrate. In addition, the head non-contact area-modified PMPC-HXLPE liner reduced the wear by 76.8%. Thus, this area may also may be important in the development of fluid-film lubrication.

Incidental durotomy (ID) is a common intraoperative complication of spine surgery. It can lead to persistent cerebrospinal fluid leakage, which may cause serious complications, including severe headache, pseudomeningocele formation, nerve root entrapment, and intracranial hemorrhage. As a result, it contributes to higher healthcare costs and poor patient outcomes. The purpose of this study was to clarify the independent risk factors that can cause ID during posterior open spine surgery for degenerative diseases in adults. We conducted a prospective multicenter study of adult patients who underwent posterior open spine surgery for degenerative diseases at 10 participating hospitals from July 2010 to June 2013. A total of 4,652 consecutive patients were enrolled. We evaluated potential risk factors, including age, sex, body mass index, American Society of Anesthesiologists physical status classification, the presence of diabetes mellitus, the use of hemodialysis, smoking status, steroid intake, location of the surgery, type of operative procedure, and past surgical history in the operated area. A multivariate logistic regression analysis was performed to identify the risk factors associated with ID. The incidence of ID was 8.2% (380/4,652). Corrective vertebral osteotomy and revision surgery were identified as independent risk factors for ID, while cervical surgery and discectomy were identified as factors that independently protected against ID during posterior open spine surgery for degenerative diseases in adults. Therefore, we identified 2 independent risk factors for and 2 protective factors against ID. These results may contribute to making surgeons aware of the risk factors for ID and can be used to counsel patients on the risks and complications associated with open spine surgery.

Background Fracture of an ossified Achilles tendon is a rare entity, and no standard treatment has been established. This is the first report to describe the use of a hamstring tendon graft and gastrocnemius fascia flap for Achilles tendon reconstruction. Case presentation We present the case of a 50-year-old woman with fracture of an ossified Achilles tendon. She presented to our clinic with acute right hindfoot pain, which started suddenly while going up the stairs. Plain radiography and magnetic resonance imaging revealed a massive ossification on the right Achilles tendon extending over 14 cm in length; the ossification was fractured at 5 cm proximal to the calcaneus insertion. Surgical treatment included removal of the ossified tendon and reconstruction with an autologous hamstring tendon graft and gastrocnemius fascia flap. One year after surgery, she was able to walk with little pain or discomfort and to stand on her right tiptoe. Conclusion Our novel surgical procedure may be useful in the treatment of fractured ossified Achilles tendons and large Achilles tendon defects.