The assessment of canal flare index and proximal femoral bone density can improve stem selection for peri-prosthetic bone maintenance after total hip arthroplasty

INTRODUCTION

Bone maintenance after total hip arthroplasty (THA) is important for implant success. This study aimed to investigate the relationship between patient characteristics and periprosthetic bone maintenance after THA for better implant selection.

MATERIALS AND METHODS

This retrospective cohort study enrolled 112 consecutive patients who underwent THA using full hydroxyapatite (HA) compaction with short (n = 55) or short-tapered wedge (n = 61) stems. Periprosthetic bone mineral density (BMD) was compared between the two groups after propensity score matching, and the relationship between periprosthetic BMD changes and patient background was analyzed.

RESULTS

Both groups showed similar periprosthetic BMD changes after adjusting for patient background using propensity score matching. Canal flare index > 3.7 in patients that underwent THA using tapered-wedge stem (odds ratio (OR), 3.2; 95% confidence interval (CI), 1.3-7.9, p = 0.013) and baseline zone 1 BMD > 0.65 in patients that received with short HA compaction stems (OR, 430.0; 95% CI 1.3-1420, p = 0.040) were associated with proximal periprosthetic bone maintenance after THA.

CONCLUSION

Considering their predictive value, canal flare index and zone 1 BMD assessment might be useful strategies for implant selection during THA.

Influence of Distal Reference Point of the Tibial Mechanical Axis on the Ankle and Hindlimb Alignment Change after Total Knee Arthroplasty

The alignment philosophy in total knee arthroplasty (TKA) has tended to shift from the gold standard of mechanically aligned technique to personalized alignment, such as the kinematically aligned (KA) technique. However, the influences of different surgical techniques on lower limb alignment relative to the ground are not fully investigated. This study investigated the influence of the ankle and hindlimb alignment change after mechanically aligned TKA and KA-TKA. The varus osteoarthritic patients who underwent TKAs were divided into a mechanically aligned TKA group (group M, n = 50) and a KA-TKA group (group K, n = 50). Radiographic parameters (hip-knee-calcaneus [HKC] angle, hip-knee-ankle [HKA] angle, talar tilt angle [TTA], and tibiocalcaneal angle [TCA]) were investigated using full-length standing radiographs. The deviation angle (ΔTA; angle between the tibial mechanical axis [TMA] and the ground tibial mechanical axis [gTMA]) and the change of ΔTA (cΔTA) were also assessed. These parameters were compared between the two groups, along with the correlation between the preoperative HKA angle and other parameters. ΔTA, TTA, and TCA showed no differences between the groups pre- and postoperatively, and no significant changes were observed postoperatively. The preoperative HKA angle showed a significant negative correlation with cΔTA in both groups (group M: r = -0.33, p = 0.02; group K: r = -0.29, p = 0.04) although no correlation was observed the with preoperative TTA and TCA. Despite no change in ΔTA after surgery, the preoperative varus deformity was associated with a change in the deviation between gTMA and TMA after surgery. A severely varus knee may be inappropriate for ground KA-TKA.

What effect does preoperative flexion contracture have on the component angles in unicompartmental knee arthroplasty?

PURPOSE

The indication for unicompartmental knee arthroplasty (UKA) has been extended to cases with some degree of preoperative knee flexion contracture recently. The purpose of this study was to clarify the effect of flexion contracture on component angles.

MATERIALS AND METHODS

Thirty-five fixed-bearing UKAs using the spacer block technique with preoperative flexion contracture (Group FC) and 35 UKAs using the same technique without preoperative flexion contracture (Group NC) were included. Using radiographs, the coronal femoral component angle, coronal tibial component angle, sagittal femoral component angle, and sagittal tibial component angle were determined. Also, extension and flexion angles of the knee as well as coronal Hip-Knee-Ankle (HKA) angles in long-leg standing radiographs were measured. The data about the thickness of the selected insert were also collected. The above results were compared between the two groups.

RESULTS

The femoral component tended to be placed in a more varus and flexed position in Group FC, while no significant difference was found about the tibial component angles. While there was no significant difference in pre- and postoperative knee flexion angles between the two groups, flexion contracture remained postoperatively in Group FC. Preoperative HKA angle was greater in Group FC while the difference was no longer significant postoperatively. Regarding the thickness of the selected insert, thicker inserts tended to be used in Group FC.

CONCLUSIONS

In fixed-bearing UKA with the spacer block technique, the femoral component tended to be placed in a flexed and varus position in the knees with preoperative flexion contracture.

Accuracy of portable navigation during THA in patients with severe developmental dysplasia of hip

INTRODUCTION

Correct cup placement in total hip arthroplasty (THA) for patients with developmental dysplasia of the hip (DDH) is considerably difficult. This study aimed to analyze the orientation accuracy of cup insertion during THA using a portable navigation system in patients with DDH.

MATERIALS AND METHODS

In this retrospective cohort study, we analyzed data from 64 patients who underwent THA using infrared stereo camera-matching portable navigation. Patients underwent THA via the anterolateral approach in the lateral decubitus position. Navigation records for intraoperative cup angles, postoperative cup angles measured on computed tomography (CT) images, and cup angle measurement differences were measured and compared between patients with non-DDH/mild DDH and severe DDH. Furthermore, the predictive factors for outliers of accurate acetabular cup placement were analyzed.

RESULTS

The average measurement absolute abduction differences (postoperative CT-navigation record) were 3.9 ± 3.5° (severe DDH) and 3.3 ± 2.6° (non-DDH/ mild DDH), and the anteversion differences were 4.7 ± 3.4° (severe DDH) and 2.3 ± 2.1° (non-DDH/ mild DDH). The anteversion difference was different between the two groups. Multivariate analysis showed that the navigation difference (absolute difference in anteversion between postoperative CT and navigation records of > 5°) was significantly associated with severe DDH (odds ratio [OR]: 3.3; p = 0.049, 95% confidence interval [CI]: 1.0-11.1) and posterior pelvic tilt (OR: 1.1; p = 0.042, 95% CI: 1.0-1.27).

CONCLUSIONS

In patients with severe DDH, it is important to pay close attention during THA using portable navigation. However, the average difference was < 5º even in patients with severe DDH, and the accuracy may be acceptable in a clinical setting when the cost is considered.

Predicting postoperative coronal alignment after fixed-bearing unicompartmental knee arthroplasty using a new morphological assessment method: the arithmetic hip-knee-ankle angle

PURPOSE

Only a few reports have been published so far on factors that predict postoperative coronal alignment after unicompartmental knee arthroplasty (UKA). The purpose of this study is to clarify the relationship between the arithmetic hip-knee-ankle angle (aHKA) and postoperative coronal alignment after medial fixed-bearing UKA.

METHODS

One hundred and one consecutive patients (125 knees) who underwent medial fixed-bearing UKA were assessed. Pre- and postoperative coronal HKA angles, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and the thickness of the tibial and femoral bone cut were measured. aHKA was calculated as 180° - LDFA + MPTA. Correlations between postoperative HKA angle and aHKA, LDFA, and MPTA were investigated by single regression analysis. After the patients were divided into three groups according to the postoperative HKA angle, i.e., HKA angle > 180°, 175° < HKA angle ≤ 180°, and HKA angle ≤ 175°, aHKA, LDFA, MPTA, preoperative HKA angle, and the thickness of the distal femoral as well as tibial bone cut were compared among the three groups.

RESULTS

aHKA and MPTA were positively correlated with postoperative HKA angle, while no correlation was found between postoperative HKA angle and LDFA. Among the three groups classified by postoperative HKA angle, significant differences were found in aHKA, MPTA, and preoperative HKA angle, while no significant difference was found in LDFA and the amount of distal femoral and tibial osteotomies.

CONCLUSIONS

aHKA was correlated with postoperative HKA angle after medial fixed-bearing UKA, which was probably due to the influence of MPTA.

Mid- to Long-Term Results of Total Knee Arthroplasty for Charcot Arthropathy of the Knee

Background

Total knee arthroplasty (TKA) for Charcot arthropathy of the knee is considered controversial because of its higher complication rate compared with that of TKA for osteoarthritis. In this study, we investigated the clinical outcomes, survival rates, and complications of primary TKA for Charcot arthropathy.

Methods

We conducted a retrospective analysis of nine patients (12 knees) with Charcot arthropathy who underwent TKA. The mean age of the patients was 63.9 ± 9.4 years (range, 52-83 years). The most frequent causative disease was diabetes mellitus (three patients). Patients' clinical outcomes, including the 2011 Knee Society Score and the range of motion, were compared between preoperative and the most recent postoperative data. The 5- and 10-year survival rates for aseptic revision, revision due to infection, and complications were examined. The mean follow-up period was 7.3 ± 3.9 years (range, 3-14 years).

Results

The 2011 Knee Society Score and the knee flexion angle significantly improved after TKA surgery (P < 0.05). The 5-year survival rates for aseptic revision, revision due to infection, and complications were 100%, 91.7%, and 83.3%, respectively; the 10-year survival rates for these parameters were the same. One patient underwent revision for insert replacement due to periprosthetic infection, and the other patient had varus/valgus instability due to soft tissue loosening.

Conclusions

The mid- to long-term results of TKA for Charcot arthropathy were generally favorable. Our findings indicate that TKA may be a viable treatment option for Charcot arthropathy.

Sex differences of NF-κB-targeted therapy for mitigating osteoporosis associated with chronic inflammation of bone

Aims

Transcription factor nuclear factor kappa B (NF-κB) plays a major role in the pathogenesis of chronic inflammatory diseases in all organ systems. Despite its importance, NF-κB targeted drug therapy to mitigate chronic inflammation has had limited success in preclinical studies. We hypothesized that sex differences affect the response to NF-κB treatment during chronic inflammation in bone. This study investigated the therapeutic effects of NF-κB decoy oligodeoxynucleotides (ODN) during chronic inflammation in male and female mice.

Methods

We used a murine model of chronic inflammation induced by continuous intramedullary delivery of lipopolysaccharide-contaminated polyethylene particles (cPE) using an osmotic pump. Specimens were evaluated using micro-CT and histomorphometric analyses. Sex-specific osteogenic and osteoclastic differentiation potentials were also investigated in vitro, including alkaline phosphatase, Alizarin Red, tartrate-resistant acid phosphatase staining, and gene expression using reverse transcription polymerase chain reaction (RT-PCR).

Results

Local delivery of NF-κB decoy ODN in vivo increased osteogenesis in males, but not females, in the presence of chronic inflammation induced by cPE. Bone resorption activity was decreased in both sexes. In vitro osteogenic and osteoclastic differentiation assays during inflammatory conditions did not reveal differences among the groups. Receptor activator of nuclear factor kappa Β ligand (Rankl) gene expression by osteoblasts was significantly decreased only in males when treated with ODN.

Conclusion

We demonstrated that NF-κB decoy ODN increased osteogenesis in male mice and decreased bone resorption activity in both sexes in preclinical models of chronic inflammation. NF-κB signalling could be a therapeutic target for chronic inflammatory diseases involving bone, especially in males.

Preclinical models for studying corticosteroid-induced osteonecrosis of the femoral head

Nontraumatic osteonecrosis of the femoral head (ONFH) is a refractory condition that commonly results in femoral head collapse and degenerative arthritis of the hip. In the early stages, surgical procedures for hip preservation, including core decompression (CD), have been developed to prevent progressive collapse of the femoral head. Optimization of bone regeneration and biological augmentation may further enhance the therapeutic efficacy of CD for ONFH. Thus, combining CD with cell-based therapy has recently been proposed. In fact, patients treated with cell-based therapy using autologous bone marrow concentrate demonstrate improved survivorship of the femoral head, compared with conventional CD alone. Preclinical research studies to investigate adjunctive therapies for CD often utilize the rabbit model of corticosteroid-induced ONFH. Mesenchymal stem cells (MSCs) are known to promote osteogenesis and angiogenesis, and decrease inflammation in bone. Local drug delivery systems have the potential to achieve targeted therapeutic effects by precisely controlling the drug release rate. Scaffolds can provide an osteoconductive structural framework to facilitate the repair of osteonecrotic bone tissue. We focused on the combination of both cell-based and scaffold-based therapies for bone tissue regeneration in ONFH. We hypothesized that combining CD and osteoconductive scaffolds would provide mechanical strength and structural cell guidance; and that combining CD and genetically modified (GM) MSCs to express relevant cytokines, chemokines, and growth factors would promote bone tissue repair. We developed GM MSCs that overexpress the anti-inflammatory, pro-reconstructive cytokines platelet-derived growth factor-BB to provide MSCs with additional benefits and investigated the efficacy of combinations of these GM MSCs and scaffolds for treatment of ONFH in skeletally mature male New Zealand white rabbits. In the future, the long-term safety, efficacy, durability, and cost-effectiveness of these and other biological and mechanical treatments must be demonstrated for the patients affected by ONFH.

Clinical use of autologous adipose-derived stromal vascular fraction cell injections for hip osteoarthritis

Introduction

Currently, studies on adipose-derived stromal vascular fraction (SVF) cells are attracting increasing attention because they have the potential to differentiate into a subset of cell types, such as bone marrow-derived mesenchymal stromal cells (MSCs), and are easier to harvest than MSCs, thus making them easier to apply clinically. This study evaluated the short-term clinical outcomes of SVF cell therapy for hip osteoarthritis (OA).

Methods

Forty-two patients were enrolled in this study; these patients received a single injection comprising an average of 3.8 (standard deviation [SD], ±1.3) × 10⁷ SVF cells into the hip joint. All patients were followed-up for at least 6 months. The mean age of the patients was 60.2 years (SD, ±9.4 years). Kellgren-Lawrence (KL) grades II, III, and IV based on radiography were 13, 13, and 16 patients, respectively. SVF cells were obtained from the subcutaneous fat of the abdomen or breech using a Celution® 800/CRS system. The average cell viability of SVF cells was 90.8% (SD, ±2.8%). Clinical assessments were performed using the Harris Hip Score (HHS), Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) score, and visual analog scale (VAS) score to evaluate pain. Images were evaluated using radiography, and T2 mapping values were obtained using a 1.5-T magnetic resonance imaging system. These clinical and imaging assessments were followed from preoperatively to 6 months postoperatively.

Results

The HHS, JHEQ score, and VAS score improved significantly from 22.5 (SD, ±16.6), 26.6 (SD, ±11.3), and 75.5 (SD, ±15.8) preoperatively to 46.8 (SD, ±27.2), 39.4 (SD, ±19.7), and 46.5 (SD, ±27.9), respectively, at 6 months postoperatively. KL grade II showed significant improvement in clinical outcome from preoperative to postoperative, while KL grade IV showed slight or little improvement. The center edge angle, acetabular head index on the radiographs, and T2 mapping values did not change significantly from preoperatively to 6 months postoperatively.

Conclusions

SVF cell injection in the hip joint showed good short-term clinical efficacy for reducing hip OA symptoms. SVF cell therapy is thus an innovative and effective treatment for hip OA.

C-C Motif Chemokine Ligand 2 Enhances Macrophage Chemotaxis, Osteogenesis, and Angiogenesis during the Inflammatory Phase of Bone Regeneration

Local cell therapy has recently gained attention for the treatment of joint diseases and fractures. Mesenchymal stem cells (MSCs) are not only involved in osteogenesis and angiogenesis, but they also have immunomodulatory functions, such as inducing macrophage migration during bone regeneration via macrophage crosstalk. C-C motif chemokine ligand 2 (CCL2), a known inflammatory mediator, is associated with the migration of macrophages during inflammation. This study examined the utility of CCL2 as a therapeutic target for local cell therapy. Using lentiviral vectors for rabbit MSCs, genetically modified CCL2 overexpressing MSCs were generated. Osteogenic differentiation assays were performed using MSCs with or without macrophages in co-culture, and cell migration assays were also performed. Additionally, co-cultures were performed with endothelial cells (ECs), and angiogenesis was evaluated using a tube formation assay. Overexpression of CCL2 did not affect bone formation under monoculture conditions but promoted chemotaxis and osteogenesis when co-cultured with macrophages. Furthermore, CCL2-overexpression promoted tube formation in co-culture with ECs. These results suggest that CCL2 induces macrophage chemotaxis and osteogenesis by promoting crosstalk between MSCs and macrophages; CCL2 also stimulates ECs to induce angiogenesis. These findings indicate that CCL2 may be a useful therapeutic target for local cell therapy in areas of bone loss.

Successful Total Knee Arthroplasty for Hoffa and Proximal Tibial Fractures: Report of Three Complex Cases After Failed Osteosynthesis Procedures

BACKGROUND Distal femoral and proximal tibial fractures often lead to nonunion and post-traumatic osteoarthritis, and total knee arthroplasty (TKA) has emerged as an effective alternative for older patients. This report includes 3 cases of successful TKA treatment. The cases involve a 42-year-old man and a 62-year-old man with Hoffa coronal fractures of the distal femur, and a 50-year-old man with a proximal tibial fracture. These patients underwent multiple osteosynthesis procedures before receiving TKA. CASE REPORT Case 1: A 42-year-old man with a displaced Hoffa's fracture had persistent knee pain. Nonunion post-initial fixation led to reoperation with iliac bone grafting and plate fixation. TKA using a Posterior Stabilized (PS)-type implant resulted in improved motion and function after 3 years. Case 2: A 62-year-old man suffered lateral condyle and ligament injuries from a displaced Hoffa's fracture. Despite plate fixation, dislocation occurred, requiring conversion. TKA with long-stem hinge-type implant, using augmentation block, led to enhanced stability and outcomes at 2 years. Case 3: A 50-year-old man's tibial nonunion, treated with plate fixation, resulted in infection and bone fusion. TKA using a constrained PS-type implant insert addressed the lateral tibial adhesions via iliotibial band (ITB) release and treated severe tibial plateau damage. Positive results were seen at 1 year. CONCLUSIONS The challenges of pseudarthrosis, like bone defects and compromised tissue, highlight the need for precise implant selection based on evaluations of bone quality, defects, knee stability, and hyperextension, rather than resorting to overly-constrained implants.

Effects of Femoral Component Design on the Deepest Point Position of the Trochlear Grove in Kinematically Aligned Total Knee Arthroplasty: A Comparison of Four Prothesis Designs

The aim of the study is to explore and compare the differences in trochlear shape and knee anatomy between four types of prostheses and preoperative native knee matched with preoperative computed tomography (CT). Thirty patients were scheduled for primary kinematically aligned total knee arthroplasty (TKA) for varus knee osteoarthritis at our hospital and the region between their pelvis to ankle joint was simulated using a CT-based three-dimensional planning software. The axial plane containing the transepicondylar axis was set as Slice A, and the 10-mm distal plane from Slice A was set as Slice B. The distances to the deepest trochlear groove between the native knee and each prosthesis and the medial and lateral facet heights were compared among the four groups. The deepest femoral trochlear groove of the prostheses was located 1.6 to 3.0 mm more medial than that of the native knee, and in the Persona group, it was significantly more medial than in the e-motion or Triathlon groups on both Slices A and B. The native knee and the medial and lateral facet heights of the four prostheses on both Slices A and B were significantly lower than those of preoperative native knees when femoral prostheses were set in the kinematically aligned (KA)-TKA position. The deepest point of the trochlear groove of the Persona group was the most medial among the four prostheses studied, and the deepest points differed depending on the prosthesis design in KA-TKA. Thus, surgeons should carefully select the type of prostheses used in KA-TKA.

Heterogeneous Cells as well as Adipose-Derived Stromal Cells in Stromal Vascular Fraction Contribute to Enhance Anabolic and Inhibit Catabolic Factors in Osteoarthritis

The stromal-vascular fraction (SVF), comprising heterogeneous cell populations and adipose-derived stromal cells (ADSCs), has therapeutic potential against osteoarthritis (OA); however, the underlying mechanism remains elusive. This study aimed to investigate the therapeutic effects of heterogeneous cells in rabbit SVF on rabbit chondrocytes. Rabbit SVF and ADSCs were autografted into knees at OA onset. The SVF (1 × 105) and low-dose ADSCs (lADSC; 1 × 104) groups adjusted for their stromal cell content were compared. Animals were euthanized 8 and 12 weeks after OA onset for macroscopic and histological analyses of OA progression and synovitis. Immunohistochemical and real-time polymerase chain reaction assessments were conducted. In vitro, immune-fluorescent double staining was performed for SVF to stain macrophages with F4/80, CD86(M1), and CD163(M2). OA progression was markedly suppressed, and synovitis was reduced in the SVF groups (OARSI histological score 8 W: 6.8 ± 0.75 vs. 3.8 ± 0.75, p = 0.001; 12 W: 8.8 ± 0.4 vs. 5.4 ± 0.49, p = 0.0002). The SVF groups had higher expression of collagen II and SOX9 in cartilage and TGF-β and IL-10 in the synovium, lower expression of MMP-13, and lower macrophage M1/M2 ratio than the lADSC groups. Immunofluorescent double staining revealed a markedly higher number of M2 than that of M1 macrophages in the SVF. The therapeutic effects of SVF on chondrocytes were superior than those of lADSCs, with enhanced anabolic and inhibited catabolic factors. Heterogeneous cells, mainly M2 macrophages in the SVF, enhanced growth factor secretion and chondrocyte-protective cytokines, thus benefiting chondrocytes and knee joint homeostasis. Overall, the SVF is a safe, relatively simple, and a useful treatment option for OA.

Glycolytic reprogramming in macrophages and MSCs during inflammation

Background

Dysregulated inflammation is associated with many skeletal diseases and disorders, such as osteolysis, non-union of fractures, osteonecrosis, osteoarthritis and orthopaedic infections. We previously showed that continuous infusion of lipopolysaccharide (LPS) contaminated polyethylene particles (cPE) caused prolonged inflammation and impaired bone formation. However, the metabolic and bioenergetic processes associated with inflammation of bone are unknown. Mitochondria are highly dynamic organelles that modulate cell metabolism and orchestrate the inflammatory responses that involve both resident and recruited cells. Glycolytic reprogramming, the shift from oxidative phosphorylation (OXPHOS) to glycolysis causes inappropriate cell activation and function, resulting in dysfunctional cellular metabolism. We hypothesized that impaired immunoregulation and bone regeneration from inflammatory states are associated with glycolytic reprogramming and mitochondrial dysfunction in macrophages (Mφ) and mesenchymal stromal cells (MSCs).

Methods

We used the Seahorse XF96 analyzer and real-time qPCR to study the bioenergetics of Mφ and MSCs exposed to cPE. To understand the oxygen consumption rate (OCR), we used Seahorse XF Cell Mito Stress Test Kit with Seahorse XF96 analyzer. Similarly, Seahorse XF Glycolytic Rate Assay Kit was used to detect the extracellular acidification rate (ECAR) and Seahorse XF Real-Time ATP Rate Assay kit was used to detect the real-time ATP production rates from OXPHOS and glycolysis. Real-time qPCR was performed to analyze the gene expression of key enzymes in glycolysis and mitochondrial biogenesis. We further detected the gene expression of proinflammatory cytokines in Mφ and genes related to cell differentiation in MSC during the challenge of cPE.

Results

Our results demonstrated that the oxidative phosphorylation of Mφ exposed to cPE was significantly decreased when compared with the control group. We found reduced basal, maximal and ATP-production coupled respiration rates, and decreased proton leak in Mφ during challenge with cPE. Meanwhile, Mφ showed increased basal glycolysis and proton efflux rates (PER) when exposed to cPE. The percentage (%) of PER from glycolysis was higher in Mφ exposed to cPE, indicating that the contribution of the glycolytic pathway to total extracellular acidification was elevated during the challenge of cPE. In line with the results of OCR and ECAR, we found Mφ during cPE challenge showed higher glycolytic ATP (glycoATP) production rates and lower mitochondrial ATP (mitoATP) production rates which is mainly from OXPHOS. Interestingly, MSCs showed enhanced glycolysis during challenge with cPE, but no significant changes in oxygen consumption rates (OCR). In accordance, seahorse assay of real-time ATP revealed glycoATP rates were elevated while mitoATP rates showed no significant differences in MSC during challenge with cPE. Furthermore, Mφ and MSCs exposed to cPE showed upregulated gene expression levels of glycolytic regulators and Mφ exposed to cPE expressed higher levels of pro-inflammatory cytokines.

Conclusion

This study demonstrated the dysfunctional bioenergetic activity of bone marrow-derived Mφ and MSCs exposed to cPE, which could impair the immunoregulatory properties of cells in the bone niche. The underlying molecular defect related to disordered mitochondrial function could represent a potential therapeutic target during the resolution of inflammation.

The efficiency of genetically modified mesenchymal stromal cells combined with a functionally graded scaffold for bone regeneration in corticosteroid-induced osteonecrosis of the femoral head in rabbits

Core decompression (CD) with mesenchymal stromal cells (MSCs) is an effective therapy for early-stage osteonecrosis of the femoral head (ONFH). Preconditioning of MSCs, using inflammatory mediators, is widely used in immunology and various cell therapies. We developed a three-dimensional printed functionally graded scaffold (FGS), made of β-TCP and PCL, for cell delivery at a specific location. The present study examined the efficacy of CD treatments with genetically modified (GM) MSCs over-expressing PDGF-BB (PDGF-MSCs) or GM MSCs co-over-expressing IL-4 and PDGF-BB and preconditioned for three days of exposure to lipopolysaccharide and tumor necrosis factor-alpha (IL-4-PDGF-pMSCs) using the FGS for treating steroid-induced ONFH in rabbits. We compared CD without cell-therapy, with IL-4-PDGF-pMSCs alone, and with FGS loaded with PDGF-MSCs or IL-4-PDGF-pMSCs. For the area inside the CD, the bone volume in the CD alone was higher than in both FGS groups. The IL-4-PDGF-pMSCs alone and FGS + PDGF-MSCs reduced the occurrence of empty lacunae and improved osteoclastogenesis. There was no significant difference in angiogenesis among the four groups. The combined effect of GM MSCs or pMSCs and the FGS was not superior to the effect of each alone. To establish an important adjunctive therapy for CD for early ONFH in the future, it is necessary and essential to develop an FGS that delivers biologics appropriately and provides structural and mechanical support.

CCL2 promotes osteogenesis by facilitating macrophage migration during acute inflammation

Novel minimally invasive strategies are needed to obtain robust bone healing in complex fractures and bone defects in the elderly population. Local cell therapy is one potential option for future treatment. Mesenchymal stromal cells (MSCs) are not only involved in osteogenesis but also help direct the recruitment of macrophages during bone regeneration via MSC-macrophage crosstalk. The C-C motif chemokine ligand 2 (CCL2) is an inflammatory chemokine that is associated with the migration of macrophages and MSCs during inflammation. This study investigated the use of CCL2 as a therapeutic target for local cell therapy. MSCs and macrophages were isolated from 10 to 12 week-old BALB/c male mice. Genetically modified CCL2 over-expressing MSCs were produced using murine CCL2-secreting pCDH-CMV-mCCL2-copGFP expressing lentivirus vector. Osteogenic differentiation assays were performed using MSCs with or without macrophages in co-culture. Cell migration assays were also performed. MSCs transfected with murine CCL2-secreting pCDH-CMV-mCCL2-copGFP expressing lentivirus vector showed higher levels of CCL2 secretion compared to unaltered MSCs (p < 0.05). Genetic manipulation did not affect cell proliferation. CCL2 did not affect the osteogenic ability of MSCs alone. However, acute (1 day) but not sustained (7 days) stimulation with CCL2 increased the alizarin red-positive area when MSCs were co-cultured with macrophages (p < 0.001). Both recombinant CCL2 (p < 0.05) and CCL2 released from MSCs (p < 0.05) facilitated macrophage migration. We demonstrated that acute CCL2 stimulation promoted subsequent osteogenesis in co-culture of MSCs and macrophages. Acute CCL2 stimulation potentially facilitates osteogenesis during the acute inflammatory phase of bone healing by directing local macrophage migration, fostering macrophage-MSC crosstalk, and subsequently, by activating or licensing of MSCs by macrophage pro-inflammatory cytokines. The combination of CCL2, MSCs, and macrophages could be a potential strategy for local cell therapy in compromised bone healing.

Bone regeneration in inflammation with aging and cell-based immunomodulatory therapy

Aging of the global population increases the incidence of osteoporosis and associated fragility fractures, significantly impacting patient quality of life and healthcare costs. The acute inflammatory reaction is essential to initiate healing after injury. However, aging is associated with "inflammaging", referring to the presence of systemic low-level chronic inflammation. Chronic inflammation impairs the initiation of bone regeneration in elderly patients. This review examines current knowledge of the bone regeneration process and potential immunomodulatory therapies to facilitate bone healing in inflammaging.Aged macrophages show increased sensitivity and responsiveness to inflammatory signals. While M1 macrophages are activated during the acute inflammatory response, proper resolution of the inflammatory phase involves repolarizing pro-inflammatory M1 macrophages to an anti-inflammatory M2 phenotype associated with tissue regeneration. In aging, persistent chronic inflammation resulting from the failure of M1 to M2 repolarization leads to increased osteoclast activation and decreased osteoblast formation, thus increasing bone resorption and decreasing bone formation during healing.Inflammaging can impair the ability of stem cells to support bone regeneration and contributes to the decline in bone mass and strength that occurs with aging. Therefore, modulating inflammaging is a promising approach for improving bone health in the aging population. Mesenchymal stem cells (MSCs) possess immunomodulatory properties that may benefit bone regeneration in inflammation. Preconditioning MSCs with pro-inflammatory cytokines affects MSCs' secretory profile and osteogenic ability. MSCs cultured under hypoxic conditions show increased proliferation rates and secretion of growth factors. Resolution of inflammation via local delivery of anti-inflammatory cytokines is also a potential therapy for bone regeneration in inflammaging. Scaffolds containing anti-inflammatory cytokines, unaltered MSCs, and genetically modified MSCs can also have therapeutic potential. MSC exosomes can increase the migration of MSCs to the fracture site and enhance osteogenic differentiation and angiogenesis.In conclusion, inflammaging can impair the proper initiation of bone regeneration in the elderly. Modulating inflammaging is a promising approach for improving compromised bone healing in the aging population.

Therapeutic effects of MSCs, genetically modified MSCs, and NFĸB-inhibitor on chronic inflammatory osteolysis in aged mice

The number of total joint replacements is increasing, especially in elderly patients, and so too are implant-related complications such as prosthesis loosening. Wear particles from the prosthesis induce a chronic inflammatory reaction and subsequent osteolysis, leading to the need for revision surgery. This study investigated the therapeutic effect of NF-ĸB decoy oligodeoxynucleotides (ODN), mesenchymal stem cells (MSCs), and genetically-modified NF-ĸB sensing interleukin-4 over-secreting MSCs (IL4-MSCs) on chronic inflammation in aged mice. The model was generated by continuous infusion of contaminated polyethylene particles into the intramedullary space of the distal femur of aged mice (15-17 months old) for 6 weeks. Local delivery of ODN showed increased bone mineral density (BMD), decreased osteoclast-like cells, increased alkaline phosphatase (ALP)-positive area, and increased M2/M1 macrophage ratio. Local injection of MSCs and IL4-MSCs significantly decreased osteoclast-like cells and increased the M2/M1 ratio, with a greater trend for IL4-MSCs than MSCs. MSCs significantly increased ALP-positive area and BMD values compared with the control. The IL4-MSCs demonstrated higher values for both ALP-positive area and BMD. These findings demonstrated the therapeutic effects of ODN, MSCs, and IL4-MSCs on chronic inflammatory osteolysis in aged mice. The two MSC-based therapies were more effective than ODN in increasing the M2/M1 macrophage ratio, reducing bone resorption, and increasing bone formation. Specifically, MSCs were more effective in increasing bone formation, and IL4-MSCs were more effective in mitigating inflammation. This study suggests potential therapeutic strategies for treating wear particle-associated inflammatory osteolysis after arthroplasty in the elderly.

MegaPro, a clinically translatable nanoparticle for in vivo tracking of stem cell implants in pig cartilage defects

Rationale: Efficient labeling methods for mesenchymal stem cells (MSCs) are crucial for tracking and understanding their behavior in regenerative medicine applications, particularly in cartilage defects. MegaPro nanoparticles have emerged as a potential alternative to ferumoxytol nanoparticles for this purpose. Methods: In this study, we employed mechanoporation to develop an efficient labeling method for MSCs using MegaPro nanoparticles and compared their effectiveness with ferumoxytol nanoparticles in tracking MSCs and chondrogenic pellets. Pig MSCs were labeled with both nanoparticles using a custom-made microfluidic device, and their characteristics were analyzed using various imaging and spectroscopy techniques. The viability and differentiation capacity of labeled MSCs were also assessed. Labeled MSCs and chondrogenic pellets were implanted into pig knee joints and monitored using MRI and histological analysis. Results: MegaPro-labeled MSCs demonstrated shorter T2 relaxation times, higher iron content, and greater nanoparticle uptake compared to ferumoxytol-labeled MSCs, without significantly affecting their viability and differentiation capacity. Post-implantation, MegaPro-labeled MSCs and chondrogenic pellets displayed a strong hypointense signal on MRI with considerably shorter T2* relaxation times compared to adjacent cartilage. The hypointense signal of both MegaPro- and ferumoxytol-labeled chondrogenic pellets decreased over time. Histological evaluations showed regenerated defect areas and proteoglycan formation with no significant differences between the labeled groups. Conclusion: Our study demonstrates that mechanoporation with MegaPro nanoparticles enables efficient MSC labeling without affecting viability or differentiation. MegaPro-labeled cells show enhanced MRI tracking compared to ferumoxytol-labeled cells, emphasizing their potential in clinical stem cell therapies for cartilage defects.

Metabolic profile of mesenchymal stromal cells and macrophages in the presence of polyethylene particles in a 3D model

BACKGROUND

Continuous cross talk between MSCs and macrophages is integral to acute and chronic inflammation resulting from contaminated polyethylene particles (cPE); however, the effect of this inflammatory microenvironment on mitochondrial metabolism has not been fully elucidated. We hypothesized that (a) exposure to cPE leads to impaired mitochondrial metabolism and glycolytic reprogramming and (b) macrophages play a key role in this pathway.

METHODS

We cultured MSCs with/without uncommitted M0 macrophages, with/without cPE in 3-dimensional gelatin methacrylate (3D GelMA) constructs/scaffolds. We evaluated mitochondrial function (membrane potential and reactive oxygen species-ROS production), metabolic pathways for adenosine triphosphate (ATP) production (glycolysis or oxidative phosphorylation) and response to stress mechanisms. We also studied macrophage polarization toward the pro-inflammatory M1 or the anti-inflammatory M2 phenotype and the osteogenic differentiation of MSCs.

RESULTS

Exposure to cPE impaired mitochondrial metabolism of MSCs; addition of M0 macrophages restored healthy mitochondrial function. Macrophages exposed to cPE-induced glycolytic reprogramming, but also initiated a response to this stress to restore mitochondrial biogenesis and homeostatic oxidative phosphorylation. Uncommitted M0 macrophages in coculture with MSC polarized to both M1 and M2 phenotypes. Osteogenesis was comparable among groups after 21 days.

CONCLUSION

This work confirmed that cPE exposure triggers impaired mitochondrial metabolism and glycolytic reprogramming in a 3D coculture model of MSCs and macrophages and demonstrated that macrophages cocultured with MSCs undergo metabolic changes to maintain energy production and restore homeostatic metabolism.

Acute Deterioration of Patient with Sudden Onset of Shock Caused by Group G Streptococcus Infection after Revision Total Knee Arthroplasty: A Case Report

BACKGROUND Periprosthetic joint infection is a difficult complication, especially in patients with rheumatoid arthritis. Life-threatening septic shock due to periprosthetic joint infection caused by group G streptococcus is rare, and there have been few reports about its treatment. We describe a successful case of sudden onset septic shock due to group G Streptococcus infection after revision total knee arthroplasty. CASE REPORT A 61-year-old woman with rheumatoid arthritis treated with biological disease-modifying antirheumatic drugs for about 12 years presented with acute right knee pain and shock 6 months after revision total knee arthroplasty. Periprosthetic joint infection caused by group G Streptococcus was diagnosed. She was admitted to the Intensive Care Unit, treated with respiratory support and dialysis, and underwent irrigation, debridement, and polyethylene liner exchange as the first surgery. At 9 days after the first surgery, she underwent the second surgery, consisting of implant removal and antibiotic spacer placement due to failure. It took approximately 7 weeks to normalize the levels of systemic markers of inflammation with intravenous antibiotics and then oral antibiotics for further 12 weeks, but re-revision total knee arthroplasty was successfully performed 1.5 years later. At a 1-year follow-up from the final surgery, she was able to walk with a cane and had no symptoms of infection. CONCLUSIONS In such cases with sudden onset of septic shock due to periprosthetic joint infection, appropriate and prompt surgical treatment should be performed to save the infected limb as well as the patient's life.

Clinical and Radiological Comparison of Single and Double Intra-articular Injection of Adipose-Derived Stromal Vascular Fraction for Knee Osteoarthritis

The aim of the article is to compare the clinical and radiological outcomes between single and double stromal vascular fraction (SVF) cell injections in patients with knee osteoarthritis (OA). We included 54 patients treated for varus knee OA with intra-articular SVF cell injection. They were divided into two groups: those who received one injection and those who received two. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, knee range of motion, and knee muscle force were assessed at baseline and 3, 6, 12, and 24 months after the first injection. The preoperative hip-knee-ankle (HKA) angle was evaluated using plain radiographs, and T2 mapping values were assessed. The total WOMAC score improved significantly in the single injection group from 3 to 24 months, but the total WOMAC score in the double injection group improved significantly at 24 months. The T2 mapping values in both the groups improved, with a significant difference at 12 months. The preoperative mean HKA angle and the correlation coefficients between the HKA angle and the total WOMAC score and between the HKA angle and the T2 mapping value of the medial femur were significant. In conclusion, double injections may provide more satisfactory treatment outcomes in patients with severe varus knee alignment. This clinical trial is registered in the Japanese Ministry of Health, Labour and Welfare (URL: https://saiseiiryo.mhlw.go.jp/published_plan/index/2) with the registration name "Cell transplantation therapy for osteoarthritis using autologous subcutaneous adipose tissue-derived regenerative (stem) cells (ADRCs)," and the registration number was "PB5160012."

Knee Stability following Posterior-Stabilized Total Knee Arthroplasty: Comparison of Medial Preserving Gap Technique and Measured Resection Technique

Novel medial preserving gap technique (MPGT) focuses on medial compartment stability and allows lateral physiological laxity. This study aimed to compare the MPGT with the measured resection technique (MRT) to determine which provides better postoperative knee stability after posterior-stabilized total knee arthroplasty (PS-TKA). Primary PS-TKA, using either MPGT (n = 65) or MRT (n = 65), was performed in 130 patients with varus knee osteoarthritis. Postoperative knee stabilities at extension and flexion were assessed using varus-valgus stress radiographs and stress epicondylar view, respectively (at 1 month, 6 months, 1 year, and 3 years postoperatively). The distance between the femoral prosthesis and polyethylene insert was measured on each medial and lateral side, defined as the medial joint opening (MJO) and lateral joint opening (LJO), respectively. Decreasing MJO or LJO translated to increasing postoperative stability. The femoral external rotation angle was compared between the two surgical techniques; postoperative knee stability was also compared between the medial and lateral compartments, as well as the surgical techniques. A significant difference was found in the femoral external rotation angle between MPGT (4.2 ± 0.2 degrees) and MRT (3.6 ± 0.1 degrees, p < 0.01). Postoperative MJOs both at extension and flexion were significantly smaller than LJOs using MPGT and MRT at all time points (p < 0.05). MJOs and LJOs at extension using MPGT were significantly smaller than those when using MRT, at 1 and 3 years postoperatively (p < 0.05). Furthermore, MJOs at flexion using MPGT were significantly smaller than those when using MRT at 6 months, 1 year, and 3 years postoperatively (p < 0.05). MPGT provided higher postoperative medial knee stability than MRT both at extension and flexion, even at 3 years after PS-TKA. This suggests that this newly developed surgical technique is a more feasible option than MRT for the preservation of postoperative medial knee stability.

P21 deficiency exhibits delayed endochondral ossification during fracture healing

INTRODUCTION

Endochondral ossification is a complex biological phenomenon involving a variety of factors and cells. Cyclin-dependent kinase inhibitor 1 (p21) inhibits cell cycle progression and is affected by external stress. We recently reported that embryonic endochondral ossification is unaffected by endogenous p21 deficiency. In this study, we evaluated whether p21 expression affects endochondral ossification during fracture healing.

METHODS

Tibial fractures were introduced into p21 knockout (p21^-/-) (n = 24) and wild-type C57BL/6 (p21^+/+) (n = 24) mice at age 10 weeks. Fracture healing was evaluated using radiological, histological, and immunohistochemical (IHC) analyses. The effect of p21 small interfering RNA (siRNA) on ATDC5 cells was assessed in vitro.

RESULTS

The Allen score for fracture healing was lower in p21^-/- mice than in p21^+/+ mice. In addition, p21^-/- mice exhibited larger calluses and lower bone mineral density. IHC analyses showed that p21^-/- mice exhibited delayed endochondral ossification via the Ihh-Runx2-Osterix pathway in vivo. Down-regulation of p21 expression in ATDC5 cells delayed endochondral ossification in vitro.

CONCLUSIONS

p21 deficiency leads to delayed endochondral ossification by attenuating the Ihh-Runx2-Osterix pathway in vivo, and p21 deficiency in hypertrophic chondrocytes causes delayed differentiation of hypertrophic chondrocytes in vitro. p21 plays a role in endochondral ossification during fracture healing.

Lateral osteoarthritis progression is associated with a postoperative residual tibiofemoral subluxation in Oxford UKA

PURPOSE

Lateral compartment osteoarthritis progression (LOP) is a major complication after Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). This study aimed to identify the association between tibiofemoral subluxation (TFS) and LOP after OUKA. Patients whose TFS was uncorrectable according to preoperative stress radiographs were hypothesised to develop residual TFS even after surgery, and thought to be more likely to develop LOP.

METHODS

The study included 201 patients who underwent medial OUKA. Fifteen patients showed increases in LOP of at least two Kellgren-Lawrence grades after surgery [progression (P) group], while the others had no progression (N group, n = 186). TFS was measured on preoperative full leg weight-bearing radiographs, valgus stress radiographs and postoperative plain radiographs. Valgus stress radiographs were obtained using a firm manual valgus force with the knee flexed at 20°. Leg alignment, Oxford knee score (OKS), and revision rates were assessed.

RESULTS

The P group had significantly higher TFS values on preoperative valgus stress (6.8° ± 2.2° vs. 4.5° ± 2.0°; P < 0.001) and postoperative radiographs (6.6° ± 2.3° vs. 4.6° ± 2.9°; P < 0.001) than the N group. Patients with postoperative residual TFS and postoperative valgus alignment were more likely to have LOP, but 9 of the 15 LOP patients did not show postoperative valgus alignment. The P group had significantly poorer postoperative OKS (33.0 ± 10.2 vs. 37.4 ± 6.5, P = 0.017) and a higher rate of revision (6/15 vs 6/186; odds ratio = 19.16; 95% CI = 4.98-76.05, P < 0.001).

CONCLUSION

OA progression in the lateral compartment after medial OUKA might be associated with postoperative residual TFS, but does not always coexist with postoperative valgus alignment. Preoperative assessment of TFS with valgus stress could be a potential predictor of postoperative residual TFS and LOP.

LEVEL OF EVIDENCE

Level III.

Sex differences in the therapeutic effect of unaltered versus NFκB sensing IL-4 over-expressing mesenchymal stromal cells in a murine model of chronic inflammatory bone loss

Wear particles from joint arthroplasties induce chronic inflammation associated with prolonged upregulation of nuclear factor kappa-B (NF-κB) signaling in macrophages and osteoclasts, which leads to osteolysis and implant loosening. Mesenchymal stromal cell (MSC)-based therapy showed great potential for immunomodulation and mitigation of osteolysis in vivo, especially in the chronic phase of inflammation. We previously generated genetically modified MSCs that secrete the anti-inflammatory cytokine interleukin 4 (IL-4) in response to NF-κB activation (NFκB-IL-4 MSCs). However, whether the impact of sexual difference in the internal environment can alter the therapeutic effects of IL-4 over-secreting MSCs that simultaneously mitigate prolonged inflammation and enhance bone formation remains unknown. This study investigated the therapeutic effects of unaltered MSCs versus NFκB-IL-4 MSCs in mitigating chronic inflammation and enhancing bone formation in male and female mice. The murine model was established by continuous infusion of polyethylene particles contaminated with lipopolysaccharide (cPE) into the medullary cavity of the distal femur for 6 weeks to induce chronic inflammation. Unaltered MSCs or NFκB-IL-4 MSCs were infused into the femoral intramedullary cavity in sex-matched groups beginning 3 weeks after primary surgery. Femurs were harvested at 6 weeks, and bone marrow density was measured with micro-computational tomography. Numbers of osteoclast-like cells, osteoblasts, and macrophages were evaluated with histochemical and immunofluorescence staining. cPE infusion resulted in severe bone loss at the surgery site, increased tartrate-resistant acid phosphatase positive osteoclasts and M1 pro-inflammatory macrophages, and decreased alkaline phosphatase expression. MSC-based therapy effectively decreased local bone loss and polarized M1 macrophages into an M2 anti-inflammatory phenotype. In females, unaltered MSCs demonstrated a larger impact in enhancing the osteogenesis, but they demonstrated similar anti-inflammatory effects compared to NFκB-IL-4 MSCs. These results demonstrated that local inflammatory bone loss can be effectively modulated via MSC-based treatments in a sexually dimorphic manner, which could be an efficacious therapeutic strategy for treatment of periprosthetic osteolysis in both genders.

Comparison between Single- and Multi-Radius Prostheses Used in Modified Kinematically Aligned Cruciate-Retaining Total Knee Arthroplasty

Kinematically aligned total knee arthroplasty (TKA) has gained interest for achieving more favorable clinical outcomes than mechanically aligned TKA. The present study aimed to compare the clinical outcomes of kinematically aligned TKAs using single-radius (SR) or multi-radius (MR) prostheses. Sixty modified kinematically aligned cruciate-retaining TKAs (30 SR and 30 MR type prostheses) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative and postoperative patellar tracking were compared between the two groups. Trochlea shape was also compared between the prostheses and preoperative native anatomy using three-dimensional simulation software. Total 2 years postoperatively, the range of motion and 2011 Knee Society Scores (KSS) were compared between the two groups. There were no differences in patellar maltracking including patellar lateral shift and tilt between the two groups; however, the ratio of intraoperative lateral retinacular release for adjusting patellar tracking was significantly higher in the MR group than in the SR group. Lateral and medial facet heights in both prostheses were understuffed compared with native knee anatomy, while the deepest point of the trochlear groove was significantly more medial in the MR group. The postoperative clinical outcomes showed no significant differences between the two groups. In conclusion, modified kinematically aligned TKAs using a SR or MR prosthesis showed no significant differences in clinical outcomes or patellar tracking when appropriate lateral retinacular release was performed.

Preoperative Condition of the Patellofemoral Joint Does Not Negatively Impact Surgical Outcomes of Lateral Unicompartmental Knee Arthroplasty in the Short Term

The relationship between patellofemoral joint (PFJ) degeneration and clinical outcomes following lateral unicompartmental knee arthroplasty (UKA) has not been well described thus far. This study aimed to investigate the relationship between the preoperative PFJ condition and postoperative outcomes and the changes in lower-limb and PFJ alignment after lateral UKA. This was a retrospective study including 54 patients (mean age 72.9 years) who underwent lateral UKA for isolated lateral knee osteoarthritis at our institution between March 2013 and January 2019. The Oxford Knee Score (OKS), the Knee Society Score-Knee (KSSK), and Knee Society Score-Function (KSSF), the degree of degeneration, tilting angle and lateral shift of the PFJ, and the hip-knee-ankle angle (HKA) were evaluated pre- and postoperatively. The average follow-up period was 2.8 (range 1-6.1) years. There was a significant improvement in the OKS, KSSK, and KSSF after lateral UKA. Preoperative degeneration of the PFJ did not correlate with the recovery of clinical scores. The degeneration, tilting angle, and lateral shift of the PFJ did not significantly progress following lateral UKA. The HKA was improved after lateral UKA, and there was no correlation between the HKA change and PFJ condition. Postoperative severe valgus knee alignment was associated with a greater tilting angle. Preoperative degeneration of the PFJ did not have a negative impact on postoperative outcomes, and no short-term changes in the degeneration, tilting angle, and lateral shift of the PFJ were observed. Correction of knee-joint alignment did not have a negative impact on the condition of the PFJ.

Evaluation of morphological characteristics for incomplete discoid medial meniscus with an oversized posterior segment

BACKGROUND

A discoid medial meniscus is rare in comparison with a discoid lateral meniscus. We encountered a new type of incomplete discoid with an oversized posterior segment. Therefore, this study aimed to report cases of medial meniscus with an oversized posterior segment and analyze the morphological characteristics by comparing them to cases with a discoid medial meniscus and normal medial meniscus.

METHODS

Four patients with an oversized posterior segment medial meniscus (oversize group, mean age: 25.3 ± 12.0 years) and seven patients with a discoid medial meniscus (discoid group, mean age: 34.4 ± 19.6) were identified using magnetic resonance imaging (MRI) and diagnosed by arthroscopic findings in our hospital. Fifty patients without medial meniscal injury were retrospectively selected as the normal group (normal group, mean age: 24.0 ± 11.3 years). The clinical symptoms were examined. The anteroposterior (AP) length of both the anterior and posterior segments, AP length ratio of the posterior segment to the AP length of the medial tibial plateau, and mediolateral (ML) width of the mid-body of the medial meniscus were also evaluated using MRI and compared among the three groups.

RESULTS

All patients in the oversize group complained of medial knee pain during deep knee flexion. In sagittal MRI, posteriorly deviated indentations were also observed at the medial tibial plateau in all cases in the oversize group. There was a significant difference in the AP length of the posterior segment between the normal and oversize groups (14.3 ± 2.8 vs. 23.6 ± 2.8 mm, P < 0.001), whereas there was no significant difference in the AP length of the anterior segment (9.1 ± 2.1 vs. 9.5 ± 1.9 mm, P = 0.869). The ML width of the mid-body in the normal, oversize, and discoid groups was 9.3 ± 1.8, 19.9 ± 2.6, and 25.8 ± 1.9 mm, respectively (normal vs. oversize group: P < 0.001, oversize vs discoid group: P = 0.01, normal vs. discoid group: P < 0.001).

CONCLUSIONS

Oversized posterior and normal anterior segments characterize this new type of incomplete discoid medial meniscus as a morphological abnormality.

Ageing attenuates bone healing by mesenchymal stem cells in a microribbon hydrogel with a murine long bone critical-size defect model

BACKGROUND

Despite the high incidence of fractures and pseudoarthrosis in the aged population, a potential role for the use of mesenchymal stem cells (MSCs) in the treatment of bone defects in elderly patients has not been elucidated. Inflammation and the innate immune system, including macrophages, play crucial roles in the differentiation and activation of MSCs. We have developed lentivirus-transduced interleukin 4 (IL4) over-expressing MSCs (IL4-MSCs) to polarize macrophages to an M2 phenotype to promote bone healing in an established young murine critical size bone defect model. In the current study, we explore the potential of IL4-MSCs in aged mice.

METHODS

A 2 mm femoral diaphyseal bone defect was created and fixed with an external fixation device in 15- to 17-month-old male and female BALB/c mice. Microribbon (µRB) scaffolds (Sc) with or without encapsulation of MSCs were implanted in the defect sites. Accordingly, the mice were divided into three treatment groups: Sc-only, Sc + MSCs, and Sc + IL4-MSCs. Mice were euthanized six weeks after the surgery; subsequently, MicroCT (µCT), histochemical and immunohistochemical analyses were performed.

RESULTS

µCT analysis revealed that bone formation was markedly enhanced in the IL4-MSC group. Compared with the Sc-only, the amount of new bone increased in the Sc + MSCs and Sc + IL4-MSC groups. However, no bridging of bone was observed in all groups. H&E staining showed fibrous tissue within the defect in all groups. Alkaline phosphatase (ALP) staining was increased in the Sc + IL4-MSC group. The Sc + IL4-MSCs group showed a decrease in the number of M1 macrophages and an increase in the number of M2 macrophages, with a significant increase in the M2/M1 ratio.

DISCUSSION

IL4 promotes macrophage polarization to an M2 phenotype, facilitating osteogenesis and vasculogenesis. The addition of IL4-MSCs in the µRB scaffold polarized macrophages to an M2 phenotype and increased bone formation; however, complete bone bridging was not observed in any specimens. These results suggest that IL4-MSCs are insufficient to heal a critical size bone defect in aged mice, as opposed to younger animals. Additional therapeutic strategies are needed in this challenging clinical scenario.

Effect on Osteogenic Differentiation of Genetically Modified IL4 or PDGF-BB Over-Expressing and IL4-PDGF-BB Co-Over-Expressing Bone Marrow-Derived Mesenchymal Stromal Cells In Vitro

The use of genetically modified (GM) mesenchymal stromal cells (MSCs) and preconditioned MSCs (pMSCs) may provide further opportunities to improve the outcome of core decompression (CD) for the treatment of early-stage osteonecrosis of the femoral head (ONFH). GM interleukin-4 (IL4) over-expressing MSCs (IL4-MSCs), platelet-derived growth factor (PDGF)-BB over-expressing MSCs (PDGF-BB-MSCs), and IL4-PDGF-BB co-over-expressing MSCs (IL4-PDGF-BB-MSCs) and their respective pMSCs were used in this in vitro study and compared with respect to cell proliferation and osteogenic differentiation. IL4-MSCs, PDGF-BB-MSCs, IL4-PDGF-BB-MSCs, and each pMSC treatment significantly increased cell proliferation compared to the MSC group alone. The percentage of Alizarin red-stained area in the IL4-MSC and IL4-pMSC groups was significantly lower than in the MSC group. However, the percentage of Alizarin red-stained area in the PDGF-BB-MSC group was significantly higher than in the MSC and PDGF-BB-pMSC groups. The percentage of Alizarin red-stained area in the IL4-PDGF-BB-pMSC was significantly higher than in the IL4-PDGF-BB-MSC group. There were no significant differences in the percentage of Alizarin red-stained area between the MSC and IL4-PDGF-BB-pMSC groups. The use of PDGF-BB-MSCs or IL4-PDGF-BB-pMSCs increased cell proliferation. Furthermore, PDGF-BB-MSCs promoted osteogenic differentiation. The addition of GM MSCs may provide a useful supplementary cell-based therapy to CD for treatment of ONFH.

Sequential changes in lower extremity function after total knee arthroplasty

PURPOSE

The effectiveness of total knee arthroplasty (TKA) for recovering ambulation and balance functions has not been investigated in detail. The present study aimed to measure functional changes in the lower limb before and after TKA by measuring ambulation function with the 3 m Timed Up and Go (TUG) test and balance function using one-leg standing time (ST).

METHODS

The study included 137 patients (116 women and 21 men) with osteoarthritis of the knee who underwent primary TKA. The mean age of the patients was 74.4 years. The mean postoperative hospital stay for rehabilitation was 23.9 days. The TUG test and ST were performed preoperatively, 2 weeks postoperatively, at discharge, and 3, 6, and 12 months postoperatively. These results from these six measurements were also compared using one-way repeated measures analysis of variance.

RESULTS

The TUG test and ST were significantly improved at 3 months after surgery. However, both the TUG test and ST did not improve further from 3 months to 6 months postoperatively or from 6 months to 1 year postoperatively.

CONCLUSION

TKA is useful for restoring lower limb function, as both ambulation and balance functions were significantly improved 3 months after surgery. However, no further improvement in ambulation or balance function was recognized beyond 3 months.

Accelerometer-Based Portable Navigation System Is Useful for Tibial Bone Cutting in Modified Kinematically Aligned Total Knee Arthroplasty

Several studies have reported better clinical outcomes following kinematically aligned total knee arthroplasty (KA-TKA) than mechanically aligned TKA. Consistent reproduction of a KA-TKA is aided by accurate tibial bone resections using computer navigation systems. This study compares an accelerometer-based portable navigation system with a conventional navigation system on tibial bone resection and clinical outcomes in KA-TKA. This study included 60 knees of patients who underwent primary KA-TKA between May 2015 and September 2017. They were randomly assigned to the OrthoPilot and iASSIST groups. A tibial bone cut was performed with 3 degree varus and 7 degree posterior slope in relation to the mechanical axis in all cases. The tibial component angle (TCA) and posterior slope angle (PSA) were evaluated by postoperative radiography, and those that deviated more than 2 degree were set as outliers. The clinical outcomes were the knee range of motion (ROM) and 2011 Knee Society Score (KSS) evaluated at 1 year postoperation. The groups were compared in terms of the TCA, PSA, number of outliers, ROM, and 2011 KSS (p < 0.05). No significant difference was observed between the groups in terms of the mean TCA, PSA, number of outliers, ROM, and categories of the 2011 KSS (objective knee indicators, symptoms, satisfaction, expectations, and functional activities). Although tibial bone cuts were performed with 3 degree varus and 7 degree posterior slope, no significant difference was observed between the OrthoPilot and iASSIST groups in terms of the accuracy of cuts or postoperative clinical result. The iASSIST was found to be a simple and useful navigation system for KA-TKA.

Radiographic Comparison of the Mechanical Axis Including Calcaneus to the Conventional Mechanical Axis in Medial Unicompartmental Knee Arthroplasty

Since a hindfoot alignment is not included in the conventional mechanical axis (hip-ankle [HA] line), a mechanical axis including the calcaneus (hip-calcaneus [HC] line) has recently attracted attention as an alternative weight-bearing line. However, there are few reports on unicompartmental knee arthroplasty (UKA) regarding the HC line. Therefore, this study aimed to compare postoperative alignments after UKA between the HA line and the HC line. Postoperatively, HC radiographs were taken in 88 consecutive patients who underwent medial UKA. The hip-knee-ankle (HKA) and hip-knee-calcaneus (HKC) angles were compared in the same patient. Regarding tibial inclination, the conventional tibial component-ankle (TCA) angle was compared with reference to the HC line (tibial component-calcaneus [TCC] angle). The mean postoperative HKA and HKC angles were 2.8 ± 2.7 and 2.0 ± 2.5 degree, respectively. The mean postoperative TCA and TCC angles were 87.7 ± 2.1 and 88.5 ± 2.1 degree, respectively. There were significant differences between the two groups in both lower limb alignment and tibial component angle. The present study indicated that the HKC and the TCC angles significantly decreased the varus alignment by approximately 1 degree compared with the HKA and TCA angles. Neutral in the HA line corresponds to valgus in reference to the HC line, which may result in overcorrection. Surgeons should consider evaluating the HC line in place of the HA line, which may affect preoperative planning and postoperative outcome during UKA. This is a Level II, diagnostic study.

Susceptibility of cyclin-dependent kinase inhibitor 1-deficient mice to rheumatoid arthritis arising from interleukin-1β-induced inflammation

We recently reported that cyclin-dependent kinase inhibitor 1 (p21) deficiency induces osteoarthritis susceptibility. Here, we determined the mechanism underlying the effect of p21 in synovial and cartilage tissues in RA. The knee joints of p21-knockout (p21^-/-) (n = 16) and wild type C57BL/6 (p21^+/+) mice (n = 16) served as in vivo models of collagen antibody-induced arthritis (CAIA). Arthritis severity was evaluated by immunological and histological analyses. The response of p21 small-interfering RNA (siRNA)-treated human RA FLSs (n = 5 per group) to interleukin (IL)-1β stimulation was determined in vitro. Arthritis scores were higher in p21^-/- mice than in p21^+/+ mice. More severe synovitis, earlier loss of Safranin-O staining, and cartilage destruction were observed in p21^-/- mice compared to p21^+/+ mice. p21^-/- mice expressed higher levels of IL-1β, TNF-α, F4/80, CD86, p-IKKα/β, and matrix metalloproteinases (MMPs) in cartilage and synovial tissues via IL-1β-induced NF-kB signaling. IL-1β stimulation significantly increased IL-6, IL-8, and MMP expression, and enhanced IKKα/β and IκBα phosphorylation in human FLSs. p21-deficient CAIA mice are susceptible to RA phenotype alterations, including joint cartilage destruction and severe synovitis. Therefore, p21 may have a regulatory role in inflammatory cytokine production including IL-1β, IL-6, and TNF-α.

External rotation of the tibial component should be avoided in lateral unicompartmental knee arthroplasty

BACKGROUND

Lateral unicompartmental knee arthroplasty (UKA) leads to good clinical outcomes for isolated lateral osteoarthritis. However, the impact of the tibial component position on postoperative outcomes in lateral UKA is yet to be determined.

PURPOSE

This study investigated the influence of tibial component malposition on clinical outcomes in lateral UKA.

MATERIALS

This was a retrospective study of 50 knees (mean age 73.5 years) who underwent lateral UKA between September 2013 and January 2019. The Oxford Knee Score (OKS), Knee Society Score - Knee (KSSK), and Knee Society Score - Function (KSSF) were evaluated. The coronal alignment, posterior slope of tibial component, tibial component rotation relative to Akagi's line (angle α), and femoral anteroposterior (AP) axis (angle β) were measured postoperatively. The average follow up period was 2.3 (range, 1-4.9) years.

RESULTS

Clinical scores were significantly improved after lateral UKA. The mean coronal alignment was 0.9° ± 3.2° varus (range, 9.1° varus to 5.5° valgus), the mean posterior slope was 6.8° ± 3.8° (range, 0.8° to 14.8°). The mean α and β angles, were 4.1° ± 5.8° (range, -9.7° to 16.5°) and 6.7° ± 7.1° (range, -7.0° to 20.5°) external rotation. The angle α had significant negative correlations with postoperative OKS (r = -0.36), KSSK (r = -0.28), and KSSF (r = -0.39), and angle β had significant negative correlations with postoperative OKS (r = -0.34) and KSSK (r = -0.46).

CONCLUSION

Excessive external rotation of the tibial component could negatively influence the postoperative outcomes of lateral UKA.

Comparison of clinical and biomechanical outcomes between the kinematic and mechanical alignment methods in total knee arthroplasty: Protocol for a multicenter randomized controlled trial

Introduction

The concept of anatomic restoration has garnered considerable interest in the form of kinematically aligned total knee arthroplasty (KA-TKA). KA-TKAs have been reported to reproduce natural alignment and kinematics. However, few randomized controlled trials (RCTs) have compared the biomechanical outcomes and the long-term clinical outcomes of KA-TKA with those of mechanically aligned TKA (MA-TKA). We aim to investigate the long-term clinical and biomechanical effects of KA-TKA and to determine whether KA-TKA or MA-TKA is more appropriate for primary TKA.

Methods

This trial will compare clinical and biomechanical outcomes of KA-TKA to those of MA-TKA. Two hundred patients will be enrolled in the RCT and randomized into KA-TKA or MA-TKA groups. Both the groups will be evaluated 1 week before the operation, on the day of the operation, 6 months after the operation, and 1, 5, and 10 years after the operation. The primary outcome is the difference between preoperative and 1-year postoperative functional activity scores of the 2011 Knee Society Score (2011 KSS) in both groups as well as the differences between the scores of both groups. The secondary outcomes will include differences in symptom, satisfaction, and expectation scores of the 2011 KSS, intraoperative kinematics evaluation, postoperative clinical outcomes and complications, pre- and postoperative gait analyses and radiograph evaluations between both KA-TKA and MA-TKA.

Comparison of plantar pressure distribution during walking and lower limb alignment between modified kinematically and mechanically aligned total knee arthroplasty

Lower extremity alignment is very important after total knee arthroplasty (TKA). This study aimed to compare the plantar pressure distribution while walking and the overall limb alignment, including the hindfoot, between kinematically (KA) and mechanically aligned (MA) TKA. The plantar pressure distribution was investigated using a pressure plate during walking and one-leg standing among four groups: patients one year after KA-TKA (KA group; n = 25), patients one year after MA-TKA (MA group, n = 25), patients with osteoarthritis (OA) undergoing non-surgical care (OA group, n = 25), and healthy controls (Healthy group; n = 25). Conventional and true mechanical axes (the line from the femoral head to the lowest point of the calcaneus) were evaluated on unipedal standing long-leg radiographs in the KA, MA, and OA groups. Results were compared using analysis of variance. The OA group showed a lateral loading pattern in the mid- and rearfoot, while the MA group showed a medial rearfoot loading pattern during walking. On the contrary, the KA and Healthy groups showed an almost equal pressure distribution between the medial and lateral rearfoot. Moreover, although both mechanical axes in the KA group passed through the knee more medially, a more neutral alignment was achieved in the true mechanical axis compared to that in the MA group. KA-TKA results in more neutral weight-bearing through the true mechanical axis and allows patients to walk while maintaining medial and lateral rearfoot pressure more evenly than MA-TKA.

Cryopreserved human adipose-derived stromal vascular fraction maintains fracture healing potential via angiogenesis and osteogenesis in an immunodeficient rat model

Background

Novel therapeutic strategies for the healing of nonunion, which has serious effects on the quality of life of patients, are needed. We evaluated the therapeutic effect of local transplantation of human stromal vascular fraction (SVF) cells on fracture healing in a rat non-healing fracture model and compared the effects between freshly isolated (F) and cryopreserved (C)-SVFs.

Methods

Non-healing fracture model was induced in the femur of female immunodeficient rats (F344/N Jcl rnu/rnu) with cauterizing periosteum. Immediately after the creation of non-healing fracture, rats received local transplantation of F and C-SVFs suspended in phosphate-buffered saline (PBS) or the same volume of PBS without cells using the same scaffold as a control group. During 8 weeks post-surgery, radiologic, histological, immunohistochemical, and biomechanical analyses were performed to evaluate fracture healing. The comparison of radiological results was performed with a chi-square test, and the multiple comparisons of immunohistochemical, histological, and biomechanical results among groups were made using a one-way analysis of variance. A probability value of 0.05 was considered to denote statistical significance.

Results

At week 8, in 60% of animals receiving F-SVF cells and in 50% of animals receiving C-SVF cells, the fracture radiologically healed with bone union whereas nonunion was observed in the control group. The healing potential was also confirmed by histological and biomechanical assessments. One of the mechanisms underlying healing involving intrinsic angiogenesis/osteogenesis was enhanced in F- and C-SVF groups compared with that in the control group. Human cell-derived vasculogenesis/osteogenesis, which was also confirmed in an in vitro differentiation assay, was also enhanced in the F- and C-SVF groups compared with that in the control groups and could be another mechanism for healing.

Conclusions

SVF cells can enhance bone healing and cryopreserved cells have almost equal potential as fresh cells. SVF cells can be used for improving nonunion bone fracture healing as an alternative to other mesenchymal stem cells and the effect of SVF cells can be maintained under cryopreservation.

Mid-flexion stability in the anteroposterior plane is achieved with a medial congruent insert in cruciate-retaining total knee arthroplasty for varus osteoarthritis

PURPOSE

This study aimed to compare the intraoperative kinematics, especially for mid-flexion femorotibial anteroposterior (AP) stability, between newly developed medial congruent (MC) inserts and cruciate-retaining (CR) inserts in navigated cruciate-retaining total knee arthroplasty (CR-TKA).

METHODS

Thirty consecutive patients with varus osteoarthritis undergoing CR-TKA using an image-free navigation system were enrolled. AP kinematics, the AP translation under manual maximum stress to the knee joint at 45° flexion, rotational kinematics, and varus-valgus laxity were evaluated using a navigation system and statistically compared between the MC and CR inserts.

RESULTS

AP kinematic analysis showed that the femoral position with the CR insert was significantly anterior at a maximum extension to 45° flexion compared with the MC insert (p < 0.05). The amount of AP translation at 45° flexion with the MC insert was significantly smaller than that with the CR insert (p < 0.05). Rotational kinematics found that the tibial position at maximum extension was significantly externally rotated with the MC inserts than with the CR inserts. Varus-valgus laxity was comparable between the MC and CR inserts.

CONCLUSION

The current results showed that greater mid-flexion AP stability was achieved with the MC inserts than with the CR inserts in CR-TKA. Intraoperative kinematics with the MC inserts more closely resembled those with preoperative conditions in CR-TKA.

LEVEL OF EVIDENCE

III, prospective comparative study.

Comparison of Clinical and Imaging Outcomes of Different Doses of Adipose-Derived Stromal Vascular Fraction Cell Treatment for Knee Osteoarthritis

Favorable clinical outcomes of intra-articular injection of adipose-derived stromal vascular fraction (SVF) cells for knee osteoarthritis (OA) have been reported, but the effects of different doses of SVF cells have not been examined. This study aimed to compare the short-term clinical and imaging outcomes of different doses of SVF cells for knee OA treatment. This study included 60 patients with knee OA who underwent intra-articular injection of SVF cells. The follow-up period was at least 12 months. Thirty patients received an intra-articular injection of 2.5×10⁷ SVF cells (low-dose group), and the remaining 30 patients received an intra-articular injection of 5.0×10⁷ SVF cells (high-dose group). Clinical evaluations were performed for the Knee injury and Osteoarthritis Outcome Score (KOOS). Imaging evaluations, including the magnetic resonance imaging Osteoarthritis Knee Score (MOAKS) features (bone marrow lesions, cartilage defects, osteophytes, Hoffa’s synovitis, and effusion synovitis), were also performed. All clinical and imaging evaluations were performed preoperatively and 12 months postoperatively and compared between the groups. In demographic data, no significant differences were found between the two groups. The total score of KOOS at 12 months postoperatively was significantly more favorable than the preoperative score in the high-dose groups. Pain and symptoms subscale scores of KOOS at 12 months postoperatively were significantly better in the high-dose group than in the low-dose group. The bone marrow lesions, Hoffa’s synovitis, and effusion synovitis improved approximately 30–40% at 12 months postoperatively compared to baseline in both groups. However, there were no significant differences in imaging evaluations between the two groups. In conclusion, the pain and symptoms subscale scores of KOOS from baseline to 12 months postoperatively improved better in the high-dose group than in the low-dose group. Our findings suggest that intra-articular injection of SVF cells for knee OA is an innovative approach.

Extent of in vivo sagittal bearing movement and its relationship with tibial posterior slopes in Oxford mobile-bearing unicompartmental knee arthroplasty

BACKGROUND

The effect of increased tibial slope on the bearing movement and clinical results in mobile-bearing unicompartmental knee arthroplasty has not been well discussed. We aimed to clarify the extent of in vivo sagittal bearing movement and bearing overhang using fluoroscopy and their relationship with the tibial posterior slopes and clinical results.

METHODS

This retrospective study included 40 patients who underwent Oxford unicompartmental knee arthroplasty for anteromedial osteoarthritis or osteonecrosis of the knee. Intraoperative posterior translation and posterior overhang of the bearing were assessed during flexion. The tibial posterior slopes were evaluated before and 2 weeks after surgery, and its increment was recorded. Clinical evaluations were also performed preoperatively and at 2 years postoperatively (maximum flexion angle, Oxford Knee Score). Single linear regression analysis was performed to assess the correlation between the tibial posterior slopes and the posterior translation and the posterior overhang and determine if these could affect the clinical outcomes.

FINDINGS

The average posterior translation was 10.7 ± 4.3 mm, and posterior overhang of the mobile bearing was found in 35% of overall patients. They were associated with increased tibial slope as well as poorer improvement in Oxford Knee Score at 2 years postoperatively.

INTERPRETATION

In Oxford unicompartmental knee arthroplasty, mobile bearing can probably move posteriorly beyond the posterior margin of the tibial component during flexion when the tibial posterior slope increases more than the original magnitude. Additionally, the posterior translation and posterior overhang closely correlated with the poorer improvement in Oxford Knee Score at 2 years postoperatively.

Gelatin hydrogels with eicosapentaenoic acid can prevent osteoarthritis progression in vivo in a mouse model

Eicosapentanoic acid (EPA) is an antioxidant and omega-3 polyunsaturated fatty acid that reduces inflammatory cytokine production. Gelatin hydrogel can be used as a carrier of a physiologically active substance that release it gradually for an average of ~3 weeks. Therefore, this study aimed to clarify the effect of EPA-incorporating gelatin hydrogels on osteoarthritis (OA) progression in vivo. Ten-week-old male C57BL/6J mice were randomly divided into six groups (n = 6): Sham, destabilization of the medial meniscus (DMM), Corn: DMM + 2 µL corn oil, EPA injection alone (EPA-I): DMM + 2 µL corn oil + 125 μg/μL EPA, Gel: DMM + gelatin hydrogels, and EPA-G: DMM + 125 μg/μL EPA-incorporating gelatin hydrogels. The mice were euthanized at 8 weeks after DMM or Sham surgery, and subjected to histological evaluation. Matrix-metalloproteinases-3 (MMP-3), MMP-13, interleukin-1β (IL-1β), p-IKK α/β, CD86, and CD163 protein expression in the synovial cartilage was detected by immunohistochemical staining. F4/80 expression was also assessed using the F4/80 score of macrophage. Histological score was significantly lower in EPA-G than in EPA-I. MMP-3-, MMP-13-, IL-1β-, and p-IKK α/β-positive cell ratio was significantly lower in EPA-G than in EPA-I. However, CD86- and CD163-positive cell ratio was not significantly different between EPA-I and EPA-G. The average-sum F4/80 score of macrophage in EPA-G was significantly lower than that in EPA-I. EPA-incorporating gelatin hydrogels were shown to prevent OA progression in vivo more effectively than EPA injection alone. Our results suggested that intra-articular administration of controlled-release EPA can be a new therapeutic approach for treating OA.

Pelvic morphology medial to the femoral head center predicts anterior coverage and range of motion after curved periacetabular osteotomy

This study observed anterior coverage extent after lateral rotation of the acetabulum, without anterior or posterior rotation, during curved periacetabular osteotomy by three-dimensional simulation, and determined if preoperative pelvic morphology affects postoperative anterior coverage and range of motion. Thirty patients scheduled for consecutive primary curved periacetabular osteotomy for developmental hip dysplasia at our hospital between 2016 and 2017 were included. Virtual acetabular osteotomies were performed to achieve a postoperative lateral center-edge angle of 30°. We measured anterior center-edge angles before curved periacetabular osteotomy through the medial one-third and one-quarter of the femoral head as an index reflecting the pelvic morphology medial to the femoral head center. The range of motion simulation was performed after virtual curved periacetabular osteotomy. Single linear regression analysis was performed to examine correlations between preoperative pelvic morphology parameters and anterior center-edge angles after virtual osteotomy. Furthermore, linear regression analysis was used to assess correlations between center-edge angles and simulated range of motions (P < .05). Anterior center-edge angle after virtual osteotomy was more strongly correlated with the anterior center-edge angle through the medial one-third (r = .92, P < .0001) and one-quarter (r = .84, P < .0001) of the femoral head. Flexion angle and internal rotation at 90° flexion showed significant correlations with anterior center-edge angle through the medial one-third (r = -.62, P = .0003; r = -.57, P = .001) and one-quarter (r = -.60, P = .0005; r = -.55, P = .002) of the femoral head and anterior center-edge angle after virtual osteotomy (r = -.67, P = .0005; r = -.62, P = .0003). Measuring preoperative parameters reflecting pelvic morphology enables surgeons to predict postoperative anterior coverage and range of motion in curved periacetabular osteotomy cases.

Intraoperative Soft Tissue Balance/Kinematics and Clinical Evaluation of Modified Kinematically versus Mechanically Aligned Total Knee Arthroplasty

Recently, kinematically aligned total knee arthroplasty has been found to achieve better clinical outcomes than mechanically aligned TKA. Despite the good clinical outcomes that are reported at short- to mid-term follow-up, intraoperative variables that are associated with a better outcome have not been measured. Therefore, this study was conducted to compare intraoperative kinematics/soft tissue balance and the clinical outcomes of patients who underwent modified kinematically (restricted tibial cut) or mechanically aligned total knee arthroplasty. Sixty cruciate-retaining total knee arthroplasties (30 modified kinematically [3-degree varus and 7-degree posterior slope in tibial cut] and 30 mechanically aligned) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative kinematics assessed by the navigation system and soft tissue balance assessed by an offset-type tensor were compared between the groups. One year postoperatively, the range of motion and 2011 Knee Society scores were compared between the groups. Kinematic assessment exhibited that tibial internal rotation during flexion was significantly maintained in the kinematic compared with the mechanical group (p < 0.05). Varus/valgus ligament balance at 90 and 120 degrees of flexion significantly maintained lateral laxity in the kinematic compared with the mechanical group (p < 0.05). Improvement of flexion angles, functional activity scores, and patient satisfaction were significantly better in the kinematic than in the mechanical group (p < 0.05). Modified kinematically aligned cruciate-retaining total knee arthroplasty maintained more tibial internal rotation and lateral laxity during flexion than mechanically aligned total knee arthroplasty; thus, the former may result in better clinical outcomes.

The influence of adipose-derived stromal vascular fraction cells on the treatment of knee osteoarthritis

Background

Adipose-derived stromal vascular fraction (SVF) cells are a mixed cell population that includes cells with multilineage potential, similar to bone marrow-derived mesenchymal stem cells. Our purpose is to investigate the influence of SVF cells in patients with knee osteoarthritis (OA) and the short-term treatment effects.

Methods

Fifty-seven patients were enrolled and treated with intra-articular injection of 2.5 × 10⁷ SVF cells into the knee joint between September 2017 and March 2018. All patients were followed up for 12 months or longer. Mean age at treatment and follow-up period were 69.4 ± 6.9 years and 13.7 ± 2.0 months, respectively. The mean preoperative hip-knee-ankle angle was 6.7 ± 3.6°. SVF cells were prepared using the Celution®800/CRS system from the patients’ abdominal or breech subcutaneous fat. The mean SVF cell viability was 90.6 ± 2.7%. Clinical evaluations were performed for range of motion, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale (VAS) for pain, and the Knee injury and Osteoarthritis Score (KOOS). Imaging evaluations, which included the hip-knee-ankle angle assessed via radiography, and T2 mapping value using a 1.5-T magnetic resonance imaging unit were also assessed. Both clinical and imaging evaluations were performed preoperatively, 1, 3, 6, and 12 months postoperatively, and compared among all timepoints (p < 0.05).

Results

Knee extension angle at 6 and 12 months postoperatively was significantly better than the preoperative angle. Total WOMAC, VAS, and KOOS scores at 1, 3, 6 and 12 months postoperatively were significantly better than preoperative scores. There was no significant difference in hip-knee-ankle angle among the five time periods. T2 mapping values of lateral femur and tibia were significantly higher 12 months postoperatively than preoperatively.

Conclusions

The short-term clinical effects of intra-articular SVF cell injection on knee OA were excellent. Intra-articular SVF cell injection is a novel and innovative approach for treating patients with knee OA.

Adequate Positioning of the Tibial Component Is Key to Avoiding Bearing Impingement in Oxford Unicompartmental Knee Arthroplasty

BACKGROUND

Bearing dislocation is a serious complication of unicompartmental knee arthroplasty (UKA) with the Oxford knee prosthesis equipped with a mobile bearing. We aimed to clarify the extent of intraoperative movement of the mobile bearing and its relationship with the positioning of prosthesis components in patients undergoing Oxford UKA.

METHODS

This retrospective study included 50 patients (50 knees) who underwent Oxford UKA for anteromedial osteoarthritis or osteonecrosis of the knee. Intraoperative bearing movement was assessed at various angles of knee flexion (0°, 30°, 60°, 90°, and 120°). We stratified patients according to the extent of bearing movement posteriorly during intraoperative knee flexion, with or without contacting the lateral wall of the tibial component (with contact, 20 knees; without contact, 30 knees). Postoperative radiographic evaluations were conducted at 1 week postoperatively to assess the positional parameters of the tibial and femoral components (varus/valgus alignment, rotation, mediolateral position). Clinical evaluations were conducted at 1 year postoperatively (maximum flexion angle, Oxford Knee Score).

RESULTS

Abnormal intraoperative movement of the mobile bearing resulting in contact with the lateral wall of the tibial component was associated with a significantly more medial position and external rotation of the tibial component, as well as poorer improvement in knee flexion angle at 1 year postoperatively.

CONCLUSION

In Oxford UKA recipients, the bearing may impinge on the lateral wall of the tibial component during flexion above 60° if the tibial component is placed too medially or exhibits pronounced external rotation, which may limit knee function improvement postoperatively.

Intra-articular autologous uncultured adipose-derived stromal cell transplantation inhibited the progression of cartilage degeneration

The role of uncultured adipose-derived stromal cells for osteoarthritis treatment remains unclear despite sporadic reports supporting their use in clinical settings. This study aimed to evaluate the therapeutic effects of autologous uncultured adipose-derived stromal cell transplantation in a rabbit osteoarthritis model. Uncultured adipose-derived stromal cells isolated from rabbits were administered via intra-articular injection into the knees after osteoarthritis onset. Animals were sacrificed at 8 and 12 weeks after osteoarthritis onset to compare the macroscopic, histological, and immunohistochemical characteristics between the uncultured adipose-derived stromal cell and control groups. Co-culture assay was also performed. The chondrocytes isolated from the model were co-cultured with adipose-derived stromal cells. The cell viability of chondrocytes and expression of chondrocyte-specific genes in the co-culture (uncultured adipose-derived stromal cell) group were compared with the mono-culture (control; chondrocytes only) group. In macroscopic and histological analyses, the uncultured adipose-derived stromal cell group showed less damage to the cartilage surface than the control group at 8 and 12 weeks after osteoarthritis onset. In immunohistochemical and co-culture assay, the uncultured adipose-derived stromal cell group showed higher expression of collagen type II and SRY box-9 and lower expression of matrix metalloproteinase-13 than the control group. The cell viability of chondrocytes in the uncultured adipose-derived stromal cell group was higher than that in the control group. Intra-articular autologous uncultured adipose-derived stromal cell transplantation inhibited the progression of cartilage degeneration in a rabbit osteoarthritis model by regulating chondrocyte viability and secreting chondrocyte-protecting cytokines or growth factors, which promote anabolic factors and inhibit catabolic factors. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1376-1386, 2019.

Effect of intraoperative soft tissue balance on postoperative recovery of ambulatory and balancing function in posterior-stabilized total knee arthroplasty

BACKGROUND

The effectiveness of total knee arthroplasty (TKA) on ambulatory and balancing function recovery should be quantitatively investigated. The present study aimed to evaluate ambulatory function using 3m-timed up and go (TUG) test and balancing function using one-leg standing time (ST) from before and after TKA, and to analyze the effects of intraoperative soft tissue balance on the postoperative improvement of their functions after TKA.

METHODS

The study included 65 patients with varus-type knee osteoarthritis who underwent primary posterior-stabilized (PS) TKA. The TUG test and ST were performed preoperatively, 1 month and 12 months after TKA. The intraoperative soft tissue balance, medial and lateral joint looseness (MJL, LJL) were evaluated with both femoral trial in place and patellofemoral joint reduced using the OFR tensor® with the knee at 0, 10, 30, 45, 60, 90, 120, and 135°. The influences of MJL and LJL on the improvement in TUG test time and ST and the 2011 Knee Society Knee Scoring System (2011 KSS) 12 months after TKA were investigated.

RESULTS

The mean TUG test times and ST were 12.7 and 13.1, 13.5 and 15.4, and 10.9 and 19.2 s preoperatively, 1 month and 12 months after TKA, respectively. The MJL at 10, 30 and 90° flexion was significantly negatively correlated with improvement in the TUG test time and the MJL at 0° flexion was significantly negatively correlated with improvement in the ST. However, the LJL was not significantly correlated with improvement in the TUG test time and the ST. The MJL at 45, 60, and 90° flexion was significantly negatively correlated with the 12-month postoperative score on the activities subscale of the 2011 KSS.

CONCLUSIONS

The higher intraoperative medial knee stability may be associated with the better postoperative improvement in ambulatory function and activities subscale of the 2011 KSS after PS-TKA.

Medial joint line elevation of the tibia measured during surgery has a significant correlation with the limb alignment changes following medial unicompartmental knee arthroplasty

PURPOSE

This study aimed to determine the correlation between the change in joint line height calculated from the resected bone and insert thickness during surgery and the change in limb alignment following unicompartmental knee arthroplasty (UKA). It was hypothesized that joint line elevation is correlated with the change in limb alignment.

METHODS

A total of 74 consecutive patients diagnosed with either isolated medial compartmental osteoarthritis (38 patients) or spontaneous osteonecrosis of the knee (36 patients) were included. The thickness of the proximal tibial and distal femoral bony cuts was measured during surgery; using these values, the medial joint line elevation of the tibia (MJLET) and medial joint line reduction of the femur (MJLRF) were defined. The correlation between the amount of change in the hip-knee-ankle (HKA) angle before and after surgery (δHKA) and the thickness of the tibial insert (TI), MJLET, or MJLRF were evaluated.

RESULTS

The mean values of δHKA, TI, MJLET, and MJLRF were 5.0° ± 2.6°, 8.5 ± 0.8, 4.4 ± 1.3, and 0.0 ± 1.1 mm, respectively. The δHKA had a significant, but weak-positive correlation with the TI (P = 0.02), and moderate-positive correlation with MJLET (P < 0.001). However, no correlation was observed between δHKA and MJLRF.

CONCLUSIONS

The MJLET measured during surgery had a significant moderate-positive correlation with the change in limb alignment following medial UKA. For clinical relevance, the surgeon can predict postoperative limb alignment after UKA by considering, intraoperatively, both the insert thickness and the depth of resection at the proximal tibia thus minimizing technical error to obtain an optimal alignment after UKA.

LEVEL OF EVIDENCE

Diagnostic study, level II.