Periacetabular osteotomy using computed tomography-based navigation: preoperative planning and accuracy evaluation.

PURPOSE: Since 2011, we have used computed tomography (CT)-based navigation to perform safe and accurate rotational acetabular osteotomy (RAO) for treating developmental dysplasia of the hip. We developed a new method with four fiducial points to improve the accuracy of a published technique. In this study, we introduced a new method to achieve reorientation in accordance with planning and evaluated its accuracy. METHODS: This study included 40 joints, which underwent RAO used CT-based navigation. In 20 joints, reorientation was confirmed by touching the lateral aspect of the rotated fragment with navigation and checking whether it matched the preoperative plan. A new fiducial point method was adopted for the remaining 20 joints. To assess the accuracy of the position of the rotated fragment in each group, postoperative radial reformatted CT images were obtained around the acetabulum and three-dimensional evaluation was performed. The accuracy of acetabular fragment repositioning was evaluated using the acetabular sector angle (ASA). RESULTS: The absolute value of ΔASA, which represents the error between preoperative planning and the actual postoperative position, was significantly smaller in the new fiducial method group than the previous method group in the area from 11:30 to 13:30 (p < 0.05). The Harris Hip Score at 1 year after surgery did not differ significantly between the previous and new fiducial point methods. CONCLUSION: The new fiducial point method significantly reduced reorientation error in the superior-lateral area of the acetabulum: significantly fewer errors and fewer cases of under-correction of lateral acetabular coverage were recorded. The four-reference fiducial method facilitates reorientation of the acetabulum as planned, with fewer errors. The effect of the improved accuracy of the fiducial point method on clinical outcomes will be investigated in the future work.

Evaluation of the Postoperative Risk of Deep Tissue Injury to the Lower Extremities Following Surgery in the Lithotomy Position.

Background The aim of this study was to determine the incidence of deep tissue injury (DTI) and potential risk factors after surgery in the lithotomy position. Methods All patients who underwent surgery in the lithotomy position under general anesthesia at a single center between January 2017 and December 2021 were retrospectively evaluated. The medical records of these patients were reviewed, and patient demographic and clinical characteristics, surgical data, and occurrence of DTI were recorded. Results During the study period, 5146 patients, 2055 (39.9%) males and 3091 (60.1%) females, with a mean age of 57.3 ± 17.4 years, underwent surgery in the lithotomy position. Seven (0.14%) patients developed DTI on their calf following surgery. All presented with severe pain and swelling, requiring prolonged hospital stay. Multivariate analysis showed that male sex (odds ratio (OR): 11.43; 95% confidence interval (CI): 1.15-113.34, p = 0.037), higher BMI (OR: 1.32; 95% CI: 1.17-1.50, p = 0.0001), and longer operation time (OR: 1.01; 95% CI: 1.004-1.014, p = 0.0002) were independent risk factors for postoperative DTI. Optimal cut-off values for BMI and operation time were 23.5 kg/m2 (sensitivity = 100%; specificity = 64%) and 285 minutes (sensitivity = 100%; specificity = 90%), respectively. Conclusion Factors significantly associated with DTI include male sex, higher BMI, and prolonged operation time.

Difference in the anterior displacement of the tibial tuberosity relative to the proximal tibial fragment between opening wedge and closed wedge high tibial osteotomies.

INTRODUCTION: This study aimed to investigate the anterior-posterior (AP) displacement of the tibial tuberosity (TT) and to assess the difference between closed wedge and opening wedge high tibial osteotomies (OWHTO and CWHTO). METHODS: One hundred consecutive knees with osteoarthritis that underwent OWHTO (50 knees) or CWHTO (50 knees) were investigated retrospectively. The femorotibial angle (FTA) was measured on AP radiographs of the knee. AP displacement of the TT, posterior tibial slope (PTS), the modified Blackburne-Peel index (mBPI), and the modified Caton-Deschamps index (mCDI) were measured on lateral radiographs of the knee. RESULTS: Patients had a mean correction angle of 12.58 ± 2.84° and 18.98 ± 5.14° (P < 0.001), with a mean AP displacement of TT of 0.84 ± 2.66 mm and 7.78 ± 3.41 mm (P < 0.001) in OWHTO and CWHTO, respectively. The AP displacement of the TT per correction of 1° was significantly greater in CWHTO than in OWHTO (P < 0.001). A significant correlation was found between the correction angle and AP displacement of the TT in CWHTO (r = -0.523, P < 0.001), but not in OWHTO. The change of PTS per correction of 1° was significantly greater in OWHTO than in CWHTO (P < 0.001). The changes of mBPI and mCDI per correction of 1° were significantly greater in CWHTO than in OWHTO (P < 0.001 and P < 0.001, respectively). CONCLUSIONS: There was greater anterior displacement of the TT in CWHTO than in OWHTO, which was correlated with the correction angle. The results suggested that CWHTO would be better than OWHTO when a concomitant anteriorization of TT is required.

Bead-beating assay during synovial fluid DNA extraction improves real-time PCR accuracy for periprosthetic joint infection.

Polymerase chain reaction (PCR)-based genetic diagnosis is a rapid and sensitive method to diagnose periprosthetic joint infection (PJI). DNA extraction using bead beating is an effective method for collecting bacterial genes in Gram-positive bacteria. We compared the detection accuracy between the conventional and bead-beating DNA extraction assay. The detection rate improved from 86.7% using the conventional method to 95.6% using the bead-beating. Our results suggest that bead-beating during DNA extraction can improve the accuracy of PCR-based genetic diagnosis of PJI.

Preoperative prediction for periprosthetic bone loss and individual evaluation of bisphosphonate effect after total hip arthroplasty using artificial intelligence.

Aims: This study was designed to develop a model for predicting bone mineral density (BMD) loss of the femur after total hip arthroplasty (THA) using artificial intelligence (AI), and to identify factors that influence the prediction. Additionally, we virtually examined the efficacy of administration of bisphosphonate for cases with severe BMD loss based on the predictive model. Methods: The study included 538 joints that underwent primary THA. The patients were divided into groups using unsupervised time series clustering for five-year BMD loss of Gruen zone 7 postoperatively, and a machine-learning model to predict the BMD loss was developed. Additionally, the predictor for BMD loss was extracted using SHapley Additive exPlanations (SHAP). The patient-specific efficacy of bisphosphonate, which is the most important categorical predictor for BMD loss, was examined by calculating the change in predictive probability when hypothetically switching between the inclusion and exclusion of bisphosphonate. Results: Time series clustering allowed us to divide the patients into two groups, and the predictive factors were identified including patient- and operation-related factors. The area under the receiver operating characteristic (ROC) curve (AUC) for the BMD loss prediction averaged 0.734. Virtual administration of bisphosphonate showed on average 14% efficacy in preventing BMD loss of zone 7. Additionally, stem types and preoperative triglyceride (TG), creatinine (Cr), estimated glomerular filtration rate (eGFR), and creatine kinase (CK) showed significant association with the estimated patient-specific efficacy of bisphosphonate. Conclusion: Periprosthetic BMD loss after THA is predictable based on patient- and operation-related factors, and optimal prescription of bisphosphonate based on the prediction may prevent BMD loss.

Differences in Diagnostic Sensitivity of Cultures Between Sample Types in Periprosthetic Joint Infections: A Systematic Review and Meta-Analysis.

BACKGROUND: Differences between the bacterial culture results of the preoperative fluid, intraoperative tissue, and sonication fluid of implants in the diagnosis of periprosthetic joint infection (PJI) are important issues in clinical practice. This study aimed to identify the differences in pooled diagnostic accuracy between culture sample types for diagnosing PJI by performing a systematic review and meta-analysis. METHODS: This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. A comprehensive literature search of PubMed, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library databases was performed. Data extraction and study assessment using the quality assessment of diagnostic accuracy studies were performed independently by two reviewers. The pooled sensitivity, specificity, summary receiver operating characteristic curve, and area under the summary receiver operating characteristic curve were estimated for each sample type. RESULTS: There were thirty-two studies that were included in the analysis after screening and eligibility assessment. The pooled sensitivities of preoperative fluid, intraoperative tissue, and sonication fluid for the diagnosis of PJI were 0.63 (95% confidence interval [CI] 0.56 to 0.70), 0.71 (95% CI 0.63 to 0.79), and 0.78 (95% CI 0.68 to 0.85), while the specificities were 0.96 (95% CI 0.93 to 0.98), 0.92 (95% CI 0.86 to 0.96), and 0.91 (95% CI 0.83 to 0.95), respectively. The area under the curves for preoperative fluid, intraoperative tissue, and sonication fluid were 0.86, 0.88, and 0.90, respectively. CONCLUSIONS: Sonication fluid culture demonstrated better sensitivity compared with the conventional culture method, and preoperative fluid culture provided lower sensitivity in diagnosing PJI.

Increased Wnt5a/ROR2 signaling is associated with chondrogenesis in meniscal degeneration.

The aim of the present study was to investigate the association between chondrogenic differentiation and Wnt signal expression in the degenerative process of the human meniscus. Menisci were obtained from patients with and without knee osteoarthritis (OA), and degeneration was histologically assessed using a grading system. Immunohistochemistry, real-time polymerase chain reaction (PCR), and Western blot analysis were performed to examine the expressions of chondrogenic markers and of the components of Wnt signaling. Histological analyses showed that meniscal degeneration involved a transition from a fibroblastic to a chondrogenic phenotype with the upregulation of SOX9, collagen type II, collagen type XI, and aggrecan, which were associated with increased Wnt5a and ROR2 and decreased TCF7 expressions. OA menisci showed significantly higher expressions of Wnt5a and ROR2 and significantly lower expressions of AXIN2 and TCF7 than non-OA menisci on real-time PCR and Western blot analysis. These results potentially demonstrated that increased expression of Wnt5a/ROR2 signaling promoted chondrogenesis with decreased expression in downstream Wnt/ß-catenin signaling. This study provides insights into the role of Wnt signaling in the process of meniscal degeneration, shifting to a chondrogenic phenotype. The findings suggested that the increased expression of Wnt5a/ROR2 and decreased expression of the downstream target of Wnt/ß-catenin signaling are associated with chondrogenesis in meniscal degeneration.

Physical Therapy May Not Be Successful for Patients With Cam-Type Femoroacetabular Impingement Syndrome and May Result in Insufficient Hip Range of Motion When Femoral Anteversion Is Less Than 16° and α-Angle Is Greater Than 65°.

PURPOSE: To identify factors associated with insufficient range of motion (ROM) improvement after the posterior pelvic tilt change in cam-type femoroacetabular impingement syndrome. METHODS: Preoperative computed tomography images from 71 consecutive patients with femoroacetabular impingement syndrome treated with arthroscopic cam resection were evaluated. Using a dynamic computer simulation program, 3-dimensional models with a 10° posterior pelvic tilt from the supine functional pelvic plane (baseline) were created by computed tomography models. Patients were divided into 2 groups: those who experienced >10° (effective group) and ≤10° (ineffective group) improvements in internal rotation at 90° flexion after a 10° posterior pelvic tilt. Demographic characteristics; preoperative range of internal rotation at 90° flexion; and radiographic parameters, including Tönnis grade, lateral center-edge angle, acetabular roof obliquity angle, central acetabular anteversion, cranial acetabular anteversion, femoral anteversion, and α angle, were compared in the 2 groups. Univariate and multivariable logistic regression analyses were performed to evaluate factors associated with insufficient ROM improvement following a 10° posterior pelvic tilt. RESULTS: The 71 patients included 58 men and 13 women, of mean age 41.4 ± 14.6 years. Posterior pelvic tilt was effective in 13 hips and ineffective in 58. Univariate analysis showed that preoperative range of internal rotation at 90°flexion, femoral anteversion, and α angle differed significantly in the 2 groups. Multivariable analysis showed that femoral anteversion <16° (odds ratio 7.4; 95% confidence interval 1.6-35; P = .012) and α angle >65° (odds ratio 6.7; 95% confidence interval 1.2-37; P = .027) were significant factors associated with insufficient ROM improvement after posterior pelvic tilt. CONCLUSIONS: Physical therapy may not be successful for patients with cam-type femoroacetabular impingement syndrome and may result in insufficient hip ROM when femoral anteversion is less than 16° and α-angle is greater than 65°. CLINICAL RELEVANCE: Patients with a prominent cam-type deformity and lower anterior femoral anteversion are at high risk of clinical failure following improvement in pelvic mobility by conservative treatment alone and are likely to benefit from surgery for cam deformity.

Shelf acetabuloplasty may inhibit range of motion: A computer simulation analysis.

Shelf acetabuloplasty has been performed in patients with developmental dysplasia of the hip (DDH); however, the appropriate position of the shelf has not been determined, particularly with respect to avoiding range of motion (ROM) loss. The aim of this study was to investigate the frequency of ROM inhibition and the influence of 3D position of the shelf following actual shelf acetabuloplasty and virtual surgery using computer simulation analysis. Computed tomography data from 15 patients with DDH who underwent shelf acetabuloplasty were collected between August 2019 and February 2022. The three-dimensional models of a hip joint were constructed using Zed Hip®. Maximal internal rotation (MIR) at 45° and 90° flexion was measured in each patient. The frequency and position of ROM inhibition was determined in a real postoperative model virtually. In addition, a second analysis using virtual acetabuloplasty was performed. Upon placing the shelf, three patterns were provided for the following four parameters: height, coronal inclination, center-edge angle (CEA), and anteroposterior position. The predictors for ROM inhibition were analyzed using a logistic regression model. In the actual postoperative model, a limitation of MIR at 90° and 45° of flexion occurred in 60% and 66.7% of patients, respectively. A higher CEA and anterior position are major factors limiting MIR. The analysis of the virtual shelf acetabuloplasty model revealed that anterior position and CEA were significant factors causing ROM inhibition. As for clinical significance, the results of the current study indicated the optimal location of the shelf to avoid iatrogenic impingement after shelf acetabuloplasty.

Safe Ultrasonography-Assisted Knee Posterior Transseptal Portal Creation Technique.

Knee arthroscopy is a minimally invasive surgical technique that allows surgeons to diagnose and treat various knee conditions using much smaller incisions than open surgery. However, it is difficult to fully visualize the posterior compartment of the knee joint using the usual anterior portal approach because of blind spots. The transseptal portal technique enables surgeons to visualize the surgical field and access instruments in the posterior compartment of the knee during arthroscopic surgery. However, creation of the posterior transseptal portal increases the risk of neurovascular injury. Particular attention should be paid to avoid damaging the saphenous nerve, common peroneal nerve, popliteal artery, and tibial nerve. Here, we describe an ultrasonography-guided surgical method for creating the posterior transseptal portal by confirming the surrounding anatomy.

Accuracy of Albumin, Globulin, and Albumin-Globulin Ratio for Diagnosing Periprosthetic Joint Infection: A Systematic Review and Meta-Analysis.

Periprosthetic joint infection (PJI) is one of the most intractable orthopedic diseases, partly because of the difficulty in differentiating septic from aseptic conditions. We aimed to evaluate and consolidate the diagnostic accuracy of the quantitative assessment of serum albumin (Alb), globulin (Glb), and albumin-globulin ratio (AGR), alone or in combination with the inflammatory marker, C-reactive protein (CRP), for PJI. We searched the PubMed, CINAHL, and Cochrane Library databases for studies that quantitatively measured Alb, Glb, or AGR for the diagnosis of PJI up until the 30 April 2023. A total of 2339 patients were included from 10 studies, including 845 patients with a definitive diagnosis of PJI and 1494 with non-PJI. The pooled sensitivity, specificity, and area under the curve (AUC) in the summary receiver-operating characteristic curve were as follows: 0.625, 0.732, and 0.715 for Alb; 0.815, 0.857, and 0.887 for Glb; 0.753, 0.757, and 0.875 for AGR; 0.788, 0.837, and 0.876 for CRP; 0.879, 0.890, and 0.917 for the CRP-Alb ratio; and 0.845, 0.855, and 0.908 for the CRP-AGR ratio. Serum Alb, Glb, and AGR levels are feasible and accurate diagnostic markers for PJI, and the combination of these markers with CRP levels may potentially improve preoperative serum diagnostic accuracy. Future prospective studies are required to verify these findings because of the small numbers of included studies.

A Comparison of the Minimum Inhibitory Concentration of Antibiotics in Staphylococcus Species Isolated From Orthopedic and Respiratory Medicine Infections.

INTRODUCTION: Antibiotic susceptibility is very important for the successful treatment of orthopedic infections, particularly for implant-related infections. While the minimum inhibitory concentrations (MICs) of Staphylococcus species were well investigated for the isolates from the respiratory tract, investigations for orthopedic pathogens are very limited. We investigated the antibiotic MIC values of Staphylococcus species isolated from orthopedic infections and compared them with those of respiratory medicine isolates used as a control. METHODS: The MICs of vancomycin (VCM), arbekacin (ABK), teicoplanin (TEIC), linezolid (LZD), and rifampicin (RFP) of a total of consecutive 259 (89 orthopedic and 170 respiratory) Staphylococcus speciesisolated in our laboratory from January 2013 to July 2016 were retrospectively reviewed. Differences between the MICs of each antibiotic in orthopedic and respiratory samples were determined. RESULTS: The number of methicillin-sensitive Staphylococcus aureus (MSSA) with a VCM MIC of <0.5 µg/mL among respiratory isolates was significantly higher than that among orthopedic isolates, while those with a MIC of 2 µg/mL were significantly lower (P = 0.0078). The proportion of methicillin-resistant coagulase-negative staphylococci (MRCNS) isolates with a VCM MIC of 2 µg/mL was significantly higher in orthopedic samples than that of methicillin-resistant Staphylococcus aureus (MRSA) (P < 0.001) in respiratory isolates. The proportion of MRCNS orthopedic isolates with an RFP MIC of >2 µg/mL was significantly higher (P = 0.0058) than that of other orthopedic staphylococci. CONCLUSIONS: The VCM MICs of Staphylococcus species from orthopedic infections were higher than those of respiratory samples, particularly MRCNS from implant-related samples.

Novel Local Antifungal Treatment for Fungal Periprosthetic Joint Infection With Continuous Local Antibiotic Perfusion: A Surgical Technique.

Fungal periprosthetic joint infections are one of the most intractable orthopedic disorders. Continuous local antibiotic perfusion allows direct administration of the antifungal agent micafungin into the local infection area at biofilm-disruptive concentrations, while controlling the dead space in addition to conventional treatment. Although the appropriate use of continuous local antibiotic perfusion requires familiarity with the characteristics of local antibiotic perfusion, it is a versatile treatment modality that can improve the clinical outcomes of fungal periprosthetic joint infection in combination with conventional treatment methods.

Bevacizumab promotes tenogenic differentiation and maturation of rat tendon-derived cells in vitro.

Previous work suggested that tenogenic differentiation of tendon stem/progenitor cells (TSPCs) was suppressed by upregulated expression of the angiogenic marker vascular endothelial growth factor (VEGF). The purpose of this study was to test the hypothesis that anti-VEGF antibody, bevacizumab, promotes in vitro tenogenic differentiation and maturation of two distinct types of TSPCs, tendon proper-derived cells (TDCs), and paratenon-derived cells (PDCs) originating from rat Achilles tendon. TDCs and PDCs were isolated from the tendon proper and the paratenon of rat Achilles tendons. TDCs and PDCs were cultured for 3 days on plates with or without VEGF. TDCs and PDCs were also cultured in collagen gel matrix, and the blocking effect of VEGF was examined by the addition of 100 ng/mL of bevacizumab. Effects of bevacizumab on tenogenic differentiation were assessed using real-time PCR, immunofluorescent staining, and western blotting. VEGF significantly attenuated expression of the Tnmd gene in both PDCs and TDCs (P<0.05). Expressions of the Scx, Tnmd, and Col1a1 genes were significantly upregulated by the addition of bevacizumab (P<0.05). Immunofluorescent staining showed that the percentage of tenomodulin-positive PDCs and TDCs was significantly higher with bevacizumab treatment than in control cultures (P<0.05). Western blotting showed that bevacizumab suppressed pVEGFR-2 protein expression in both PDCs and TDCs. Bevacizumab promoted the in vitro tenogenic differentiation and maturation of two distinct TSPCs derived from rat Achilles tendon. Since the previous studies demonstrated that TSPCs have a potential to contribute to tendon repair, attenuating VEGF levels in TSPCs by administration of bevacizumab is a novel candidate therapeutic option for promoting tendon repair.

Application of Intraoperative CT-Ultrasound Fusion Imaging in Hip Endoscopy for Treatment of Iatrogenic Impingement Due to PLLA Screw: A Novel Surgical Technique.

Ultrasound-assisted surgery is becoming an established tool in the medical field. The addition of imagery to ultrasound-assisted surgery may enable one to perform a procedure in a safer and more accurate manner. This can be achieved through fusion imaging (fusion), a technology that synchronizes MRI or CT images with ultrasound images. We describe intraoperative CT-ultrasound fusion-guided (or -assisted) hip endoscopy for the removal of an impinging poly L-lactic acid screw, which was difficult to identify on fluoroscopy during surgery. The fusion technology enables merging two advantages of ultrasound: the real-time guidance capabilities and CT or MRI and the bird's eye view that makes minimally invasive arthroscopic and endoscopic surgery less invasive, precise, and safe.

Tranexamic acid administration for the prevention of periprosthetic joint infection and surgical site infection: a systematic review and meta-analysis.

INTRODUCTION: Tranexamic acid (TXA) has been widely utilized to reduce blood loss and allogeneic transfusions in patients who undergo lower limb arthroplasty. In recent years, there have been several articles reporting the incidence of periprosthetic joint infection (PJI) as a primary outcome of TXA administration, but no meta-analysis has been conducted to date. The present systematic review and meta-analysis evaluated the efficacy of TXA administration in preventing PJI and surgical site infection (SSI). MATERIALS AND METHODS: Pubmed, CINAHL, and the Cochrane Library bibliographic databases were searched for studies published by May 24, 2022, that evaluated the effects of TXA on PJI and SSI. Two researchers screened the identified studies based on the PRISMA flow diagram. The quality of each randomized clinical trial was assessed using Version 2 of the Cochrane risk-of-bias tool for randomized trials (ROB2.0), and the quality of cohort and case-control studies was assessed by risk of bias for nonrandomized studies (ROBANS-I). RESULTS: Of the 2259 articles identified from the database search, 31 were screened and selected. Treatment with TXA significantly reduced the incidence of overall infection, including PJI, SSI, and other infections (OR 0.55; 95% CI 0.49-0.62) (P < 0.00001), and that of PJI alone (OR 0.53; 95% CI 0.47-0.59) (P < 0.00001). TXA reduced the incidence of overall infection in patients who underwent total hip arthroplasty (THA; OR 0.51; 95% CI: 0.35-0.75) (P = 0.0005) and total knee arthroplasty (TKA; OR 0.55; 95% CI: 0.43-0.71) (P < 0.00001). Intravenous administration of TXA reduced the incidence of overall infection (OR 0.59; 95% CI 0.47-0.75) (P < 0.0001), whereas topical administration did not. CONCLUSIONS: Intravenous administration of TXA reduces the incidence of overall infection in patients undergoing both THA and TKA. LEVEL OF EVIDENCE: Level III.

Targeting of Periprosthetic Muscles for the Ultrasonographic Screening of Hip Abnormalities in Hip Resurfacing Arthroplasty Patients.

BACKGROUND: Hip resurfacing arthroplasty (HRA) patients require subsequent annual screening for postoperative complications. Ultrasonography may be useful for this purpose but lacks a screening protocol for hips. The purpose of this study was to evaluate the accuracy of ultrasonography for detecting postoperative complications in HRA patients using a screening protocol that specifically targets periprosthetic muscles. METHODS: We enrolled 45 hips from 40 HRA patients with a mean follow-up period of 8.2 years. MRI and ultrasonography scans were simultaneously conducted at follow-up. The ultrasonography assessments were conducted on the anterior part of the hip that targets iliopsoas, sartorius, rectus femoris, lateral with anterior superior and inferior iliac spine (ASIS and AIIS) as bony landmarks, and the lateral and posterior parts that target fascia tensor, short rotators, and gluteus minimus, medius, and maximus with greater trochanter and ischial tuberosity as bony landmarks. The accuracy of diagnosing postoperative abnormalities and the visibility of periprosthetic muscles were compared between these two modalities. RESULTS: Both MRI and ultrasonography detected an abnormal region in eight cases comprising two infections, two pseudotumors, and four patients with greater trochanteric bursitis. Among these cases, four hips required implant removal. The increase in anterior space, measured as the distance between the iliopsoas and resurfacing head, was a good indicator for the abnormal mass in these four HRA cases. In the assessment of periprosthetic muscles, MRI showed a much lower visibility than ultrasonography in the iliopsoas (6.7% vs. 100%), gluteus minimus (6.7% vs. 88.9%), and short rotators (8.8% vs. 71.4%) due to implant halation. CONCLUSIONS: By targeting periprosthetic muscles, ultrasonography can detect postoperative complications as effectively as MRI assessments in HRA patients. Ultrasonography has superior visibility in the periprosthetic muscles of HRA patients, indicating its utility for the screening of small legions in these cases which may not be visible by MRI.

Monitoring of blood biochemical markers for periprosthetic joint infection using ensemble machine learning and UMAP embedding.

INTRODUCTION: Periprosthetic joint infection (PJI) is a serious complication after total joint arthroplasty. It is important to accurately identify PJI and monitor postoperative blood biochemical marker changes for the appropriate treatment strategy. In this study, we aimed to monitor the postoperative blood biochemical characteristics of PJI by contrasting with non-PJI joint replacement cases to understand how the characteristics change postoperatively. MATERIALS AND METHODS: A total of 144 cases (52 of PJI and 92 of non-PJI) were reviewed retrospectively and split into development and validation cohorts. After exclusion of 11 cases, a total of 133 (PJI: 50, non-PJI: 83) cases were enrolled finally. An RF classifier was developed to discriminate between PJI and non-PJI cases based on 18 preoperative blood biochemical tests. We evaluated the similarity/dissimilarity between cases based on the RF model and embedded the cases in a two-dimensional space by Uniform Manifold Approximation and Projection (UMAP). The RF model developed based on preoperative data was also applied to the same 18 blood biochemical tests at 3, 6, and 12 months after surgery to analyze postoperative pathological changes in PJI and non-PJI. A Markov chain model was applied to calculate the transition probabilities between the two clusters after surgery. RESULTS: PJI and non-PJI were discriminated with the RF classifier with the area under the receiver operating characteristic curve of 0.778. C-reactive protein, total protein, and blood urea nitrogen were identified as the important factors that discriminates between PJI and non-PJI patients. Two clusters corresponding to the high- and low-risk populations of PJI were identified in the UMAP embedding. The high-risk cluster, which included a high proportion of PJI patients, was characterized by higher CRP and lower hemoglobin. The frequency of postoperative recurrence to the high-risk cluster was higher in PJI than in non-PJI. CONCLUSIONS: Although there was overlap between PJI and non-PJI, we were able to identify subgroups of PJI in the UMAP embedding. The machine-learning-based analytical approach is promising in consecutive monitoring of diseases such as PJI with a low incidence and long-term course.

A rare case of intra-articular synovial sarcoma of the hip joint: a case report with intra-articular findings via hip arthroscopy.

Although synovial sarcoma is a relatively common soft tissue sarcoma, primary intra-articular cases are extremely rare. Herein, we report a case of primary intra-articular synovial sarcoma arising from the hip joint, that was initially treated with hip arthroscopy. A 42-year-old male presented with a history of pain in the left hip for 7 years. Radiography and magnetic resonance imaging revealed the primary intra-articular lesion and simple excision with an arthroscopy was performed. Histological findings revealed spindle cell proliferation with abundant psammoma bodies. SS18 gene rearrangement was confirmed by fluorescence in situ hybridization, and the tumor was diagnosed as synovial sarcoma. Adjuvant chemotherapy and radiotherapy were performed. Local control without metastasis was achieved 6 months after excision. This is the first case of intra-articular synovial sarcoma of the hip joint excised via hip arthroscopy. When an intra-articular lesion is identified, malignancies such as synovial sarcoma should be included in the differential diagnosis.

Effects of changes in whole-body alignment on ipsilateral knee pain after total hip arthroplasty.

BACKGROUND: Total hip arthroplasty decreases hip pain and often reduces knee pain in patients with hip osteoarthritis. Whole-body alignment may be associated with knee pain, but to our knowledge this relationship has not been previously investigated. The purpose of this study was to investigate the effect of changes in whole-body alignment on ipsilateral knee pain in patients after total hip arthroplasty. METHODS: In total, 94 patients with unilateral hip osteoarthritis who underwent total hip arthroplasty were enrolled in this study. A visual analog scale (VAS) was used to investigate perioperative knee pain. An EOS 2D/3D X-ray system was used to quantify the whole-body alignment of the spine, pelvis, and lower extremities in the standing position. The relationship between perioperative changes in knee pain and whole-body alignment was investigated. RESULTS: Among 61 patients who had preoperative ipsilateral knee pain, pain resolved in 30 (50%) and persisted in 31 (50%) after surgery. In these patients, average ipsilateral knee pain decreased significantly after surgery, from 41 mm to 14 mm on the VAS (P < 0.01). Preoperative knee pain was correlated with femorotibial rotation, and postoperative knee pain was correlated with K-L grade, preoperative knee pain visualized analog scale, and preoperative sagittal vertical axis. Multiple linear regression identified preoperative sagittal vertical axis as significantly associated with residual postoperative ipsilateral knee pain. CONCLUSIONS: Ipsilateral knee pain decreased in half of patients after total hip arthroplasty. Patients with a considerable forward-bent posture may have residual ipsilateral knee pain after total hip arthroplasty.