Depletion of b-series ganglioside prevents limb length discrepancy after growth plate injury.

INTRODUCTION: Growth plate damage in long bones often results in progressive skeletal growth imbalance and deformity, leading to significant physical problems. Gangliosides, key glycosphingolipids in cartilage, are notably abundant in articular cartilage and regulate chondrocyte homeostasis. This suggests their significant roles in regulating growth plate cartilage repair. METHODS: Chondrocytes from 3 to 5 day-old C57BL/6 mice underwent glycoblotting and mass spectrometry. Based on the results of the glycoblotting analysis, we employed GD3 synthase knockout mice (GD3-/-), which lack b-series gangliosides. In 3-week-old mice, physeal injuries were induced in the left tibiae, with right tibiae sham operated. Tibiae were analyzed at 5 weeks postoperatively for length and micro-CT for growth plate height and bone volume at injury sites. Tibial shortening ratio and bone mineral density were measured by micro-CT. RESULTS: Glycoblotting analysis indicated that b-series gangliosides were the most prevalent in physeal chondrocytes among ganglioside series. At 3 weeks, GD3-/- exhibited reduced tibial shortening (14.7 ± 0.2 mm) compared to WT (15.0 ± 0.1 mm, P = 0.03). By 5 weeks, the tibial lengths in GD3-/- (16.0 ± 0.4 mm) closely aligned with sham-operated lengths (P = 0.70). Micro-CT showed delayed physeal bridge formation in GD3-/-, with bone volume measuring 168.9 ± 5.8 HU at 3 weeks (WT: 180.2 ± 3.2 HU, P = 0.09), but normalizing by 5 weeks. CONCLUSION: This study highlights that GD3 synthase knockout mice inhibit physeal bridge formation after growth plate injury, proposing a new non-invasive approach for treating skeletal growth disorders.

Radiation therapy improves survival in elderly patients with localized extremity soft tissue sarcoma.

BACKGROUND: This study aims to evaluate the efficacy of radiation therapy in enhancing survival outcomes among elderly patients diagnosed with localized extremity soft tissue sarcomas (STSs). Furthermore, it seeks to explore whether the survival benefits conferred by radiation therapy differ according to tumor characteristics and treatment modalities. METHODS: We conducted a retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER) database to identify patients aged 80 years and older diagnosed with localized extremity STSs. The study assessed 1498 eligible patients, analyzing cancer-specific survival (CSS) and overall survival (OS) through Kaplan-Meier survival analysis and Cox proportional hazards modeling. Propensity score matching was employed to adjust for potential confounders. RESULTS: Among the analyzed patients, 773 patients underwent radiation therapy (Radiation group), while 725 patients either did not receive radiation therapy or it was unknown if they had (No-Radiation group). The 5-year OS rate was 40% in the radiation group compared to 38% in the no-radiation group. After propensity score matching, radiation therapy was associated with a significant improvement in OS (P = 0.005, HR = 0.8, 95% CI 0.7-0.9). Subgroup analyses indicated that patients undergoing primary tumor resection benefited most from radiation therapy in terms of OS. CONCLUSION: Radiation therapy is associated with improved overall survival in elderly patients with localized extremity STSs. These findings suggest that radiation therapy should be considered as a key component of the treatment strategy for this patient population, taking into account individual patient characteristics and comorbidities.

Atelocollagen-associated autologous chondrocyte implantation for the repair of large cartilage defects of the knee: Results at three to seven years.

BACKGROUND: Recently, various types of engineered autologous chondrocyte implantation (ACI) have been developed. Atelocollagen-associated ACI (A-ACI) is the only ACI procedure covered by Japanese Health Insurance since 2013. The indications of the A-ACI are traumatic cartilage defects and osteochondral dissecans (OCD) for knee joints. PURPOSE: To evaluate midterm clinical results after A-ACI for the treatment for full-thickness cartilage defects of the knee. METHODS: Thirteen consecutive patients who underwent A-ACI between 2014 and 2018 had been prospectively enrolled in this study. There were 11 men and 2 women with a mean age of 34 years at the time of surgery. The causes of the cartilage defect were trauma in 10 knees and OCD in 3 knees. The total number of lesions was 15, which were comprised of the medial femoral condyle in 5 knees, the lateral femoral condyle in 5 knees, and the femoral trochlea in 5 knees. The mean size of the lesion was 5.3 cm2. Each knee was clinically and radiologically evaluated preoperatively and postoperatively. RESULTS: The mean Lysholm score improved significantly from 74.0 points to 94.0 points (p = 0.008) and each subscale in Knee injury and Osteoarthritis Outcome Score improved significantly (p < 0.001) at the mean final follow-up period of 51 months (range, 36-84 months). The magnetic resonance observation of cartilage repair tissue 2.0 score at the mean follow-up of 38 months was significantly higher than that at 2 months postoperatively (p = 0.014). According to the International Cartilage Repair Society (ICRS) grading scale, 3 knees were graded as normal, 3 knees as nearly normal, and 1 knee as severely abnormal in second-look arthroscopic evaluation at a mean of 22 months (range, 8-41 months) after A-ACI. CONCLUSION: The present study showed a significant subjective and objective clinical improvement in the A-ACI for large cartilage defects of the knee at a mean follow-up of 51 months (range, 36-84 months).

Amputation surgery associated with shortened survival in patients with localized soft tissue sarcoma.

BACKGROUND: The objectives of this study were to clarify whether localized extremity soft tissue sarcoma (STS) patients who underwent amputation surgery experienced worsened survival and to identify those patients for whom amputation surgery worsened survival. METHODS: Using the Surveillance, Epidemiology, and End Results database, we identified 8897 patients with localized extremity STS between 1983 and 2016. Of these 6431 patients, 733 patients underwent amputation surgery (Amputation group), and 5698 underwent limb-sparing surgery (Limb-sparing group). RESULTS: After adjusting for patient background by propensity score matching, a total of 1346 patients were included. Patients in the Amputation group showed worsened survival (cancer-specific survival (CSS): hazard ratio (HR) = 1.42, 95% confidence interval (CI) 1.15-1.75, overall survival (OS): HR = 1.41, 95%CI 1.20-1.65). In subclass analysis, patients with high-grade STS, spindle cell sarcoma and liposarcoma in the Amputation group showed shortened survival (high-grade-CSS: HR = 1.44, 95%CI 1.16-1.77, OS: HR = 1.38, 95%CI 1.18-1.62; spindle cell sarcoma-CSS: HR = 4.75, 95%CI 1.56-14.4, OS: HR = 2.32, 95%CI 1.45-3.70; liposarcoma-CSS: HR = 2.91, 95%CI 1.54-5.50, OS: HR = 2.32, 95%CI 1.45-3.70). CONCLUSIONS: Survival was shortened in localized extremity STS patients who received amputation surgery.

Glycosphingolipids in Osteoarthritis and Cartilage-Regeneration Therapy: Mechanisms and Therapeutic Prospects Based on a Narrative Review of the Literature.

Glycosphingolipids (GSLs), a subtype of glycolipids containing sphingosine, are critical components of vertebrate plasma membranes, playing a pivotal role in cellular signaling and interactions. In human articular cartilage in osteoarthritis (OA), GSL expression is known notably to decrease. This review focuses on the roles of gangliosides, a specific type of GSL, in cartilage degeneration and regeneration, emphasizing their regulatory function in signal transduction. The expression of gangliosides, whether endogenous or augmented exogenously, is regulated at the enzymatic level, targeting specific glycosyltransferases. This regulation has significant implications for the composition of cell-surface gangliosides and their impact on signal transduction in chondrocytes and progenitor cells. Different levels of ganglioside expression can influence signaling pathways in various ways, potentially affecting cell properties, including malignancy. Moreover, gene manipulations against gangliosides have been shown to regulate cartilage metabolisms and chondrocyte differentiation in vivo and in vitro. This review highlights the potential of targeting gangliosides in the development of therapeutic strategies for osteoarthritis and cartilage injury and addresses promising directions for future research and treatment.

Analysis of foot-originating malignant bone tumors: Epidemiology, characteristics, and survival outcomes.

BACKGROUND: The study examines the characteristics and outcomes of foot-originating malignant bone tumors via Surveillance Epidemiology and End Results (SEER) database analysis. METHODS: A retrospective review of 14,695 malignant bone tumor cases from 2000 to 2019 was conducted. RESULTS: Of the eligible cases, 147 (2.3 %) were foot-origin tumors, typically smaller and more commonly treated with surgery than those in other locations. These tumors were more frequently treated with surgical resection, with a higher proportion undergoing amputation. In contrast, foot-origin tumors were less often managed with chemotherapy and radiation. Foot-origin tumors exhibited higher survival rates compared to non-foot-origin tumors as shown in univariate analysis, although multivariate analysis did not reflect significant differences. CONCLUSION: Foot-originating malignant bone tumors tend to be smaller and are frequently surgically treated, correlating with favorable survival outcomes. These findings point to early detection as a potential factor in the improved survival rates, not necessarily the tumor's origin.

Comparison of clinical features between patients with bone and soft tissue fibrosarcomas.

BACKGROUND AND OBJECTIVES: Fibrosarcomas predominantly arise in soft tissues, but can also develop in bone. Because of their rarity, whether bone development has an impact on clinical features has not been addressed. METHODS: We included fibrosarcoma patients diagnosed between 1983 and 2016 in the Surveillance, Epidemiology, and End Results database. Differences in clinical features between fibrosarcoma of bone (FS-B) and fibrosarcoma of soft tissue (FS-ST) were investigated. RESULTS: After excluding patients without information regarding cause of death, site of origin, distant tumor or survival, 1443 patients were included. Of those, 98 patients had FS-B. Patients with FS-B were younger, more frequently male, with fibrosarcomas that more often developed in an extremity and were histologically high-grade. In contrast, no difference in potential to metastasize was observed. Survival was almost equal between FS-B and FS-ST (FS-B/FS-ST: cancer-specific survival, hazard ratio [HR]: 1.2, 95% confidence interval [CI]: 0.8-1.7; overall survival, HR: 1.3, 95% CI: 0.9-1.7). CONCLUSIONS: Our results clearly indicated that patient backgrounds differed, such as younger age and greater tendencies to affect males, develop in an extremity and show high-grade tumor in patients with FS-B. In contrast, no differences were observed in distant metastatic potential or survival.

Liver metastasis in soft tissue sarcoma at initial presentation.

BACKGROUND AND OBJECTIVES: Noncontrast computed tomography of the chest is the standard imaging modality for cancer staging in patients with soft tissue sarcoma (STS), but appropriate candidates for liver screening have not been clarified. METHODS: We reviewed all patients with STS diagnosed between 2010 and 2018 in the Surveillance, Epidemiology, and End Results database. Incidence of liver metastasis at initial presentation and high incidence of liver metastasis by histological subtype were investigated. In addition, risk factors for liver metastasis were investigated by multiple logistic regression analysis. RESULTS: After excluding patients without information about liver metastasis, cause of death or primary liver tumor, 47 260 patients were included in this study. Of those, 1471 patients (3.2%) showed liver metastasis at initial presentation. The histological subtype showing the highest incidence of liver metastasis was desmoplastic small round cell tumor (30.3%), followed by malignant hemangioendothelioma (11.5%) and angiomyoliposarcoma (10.5%). Deep-rooted tumor, location in the body wall, retroperitoneum, or thorax/peritoneum, high histological grade, and higher T stage were associated with higher incidences of liver metastasis at initial presentation. CONCLUSION: Risk factors for liver metastasis were deep location, trunk development, larger tumor size, high histological grade, and specific histological subtypes.

The effect of local injection of tranexamic acid into peri-articular tissue versus drain clamping in total knee arthroplasty: a randomized controlled trial.

BACKGROUND: Tranexamic acid (TXA) is used as a synthetic anti-fibrinolytic agent for total knee arthroplasty (TKA) to reduce postoperative bleeding. Though the effects on bleeding reduction of several methods of administering TXA have been demonstrated, the optimal method remains controversial. Recently, the hemostatic effect of periarticular local injection of TXA during TKA was reported. Although this method can be expected to suppress postoperative bleeding without placing a drain, its hemostatic effect has not yet been assessed in comparison with local injection and other methods of administering TXA. The aim of this randomized, prospective study was to assess the efficacy of local injection of TXA during TKA. METHODS: To confirm the effect of the local injection of TXA, drain clamping was set as the control. The subjects included a prospective series of 109 patients randomly divided into 2 groups: the local injection (group L) and the drain clamping (group D). The main outcome measure was postoperative bleeding. Secondary outcomes included pain, physical measurements, and laboratory findings. RESULTS: The calculated total blood loss (CTBL) in groups L and D was nearly equal and did not show the non-inferiority of group L to group D (883 ± 248 vs. 841 ± 257 ml, P = .564). Drained blood loss was significantly higher in group L than in group D (395 ± 130 vs 276 ± 78.8 ml, P < .0001). There was no significant difference in hidden blood loss between the groups (488 ± 269 vs 565 ± 261 ml, P = .131). The other laboratory findings and physical measurements were identical between the groups. CONCLUSIONS: Although CTBL in group L did not show non-inferiority to group D, the local injection of TXA was considered to be superior for suppressing bleeding considering the risk of the adverse effects of using a drain. TRIAL REGISTRATION: This was a randomized, prospective study registered with UMIN Clinical Trials Registry (Registration number: UMIN000036146, date of disclosure: 10/3/2019).

Stress on the posteromedial region of the proximal tibia increased over time after anterior cruciate ligament injury.

PURPOSE: Anterior cruciate ligament (ACL) injury induces anterior and rotatory instability of the knee. However, the effect of this instability on the stress distribution in the knee joint in living participants is not clear. The aim of this study was to compare the distribution pattern of subchondral bone density across the proximal tibia in the knees with and without ACL injury, and to investigate the correlation between the distribution patterns of the subchondral bone density and the duration of ACL-deficiency. METHODS: Radiographic and computed tomography (CT) data pertaining to 20 patients with unilateral ACL injury without combined injury (ACL-deficient group) and 19 nontraumatic subjects (control group) were collected retrospectively. Subchondral bone density of the proximal tibia was assessed using CT-osteoabsorptiometry. Both the medial and lateral compartments of the proximal tibia were divided into three subregions of equal width in the sagittal direction. The percentage of high subchondral bone density areas (HDA%) in each subregion was quantitatively analyzed. RESULTS: HDA% of the posteromedial region was significantly higher in the ACL-deficient group (mean: 21.6%) than in the control group (14.7%) (p = 0.002). In contrast, HDA% of the anteromedial region was significantly lower in the ACL-deficient group (9.4%) than in the control group (15.3%) (p = 0.048). The logarithm of the time elapsed from ACL injury to CT examination showed a significant correlation with HDA% in the posteromedial region (p = 0.032). CONCLUSIONS: Subchondral bone density in the posteromedial region significantly increased after ACL injury and correlated with the duration of ACL-deficiency in semi-log manner in meniscus intact knees. The increase in stress on the posteromedial region after ACL injury, which induces a change in the subchondral bone density, justifies early ACL reconstruction after ACL injury.

Hallux Valgus With Second Brachymetatarsia Discovered Accidentally: A Case Report.

Hallux valgus deformity is one of the most common foot and ankle diseases, while brachymetatarsia is a rare foot anomaly with pathological shortening of a metatarsal bone. We present a case of hallux valgus deformity possibly due to second brachymetatarsia. As the hallux valgus was associated with dorsal dislocation of the second toe that made it difficult to evaluate the length of the second toe, the patient was unaware of the second metatarsal shortening until the lengths of the toes compared by manual reposition of the second MTP joint. In this case, proximal osteotomy of the first metatarsal on the hallux valgus and single-stage bone lengthening of the second metatarsal with iliac bone grafting on the second brachymetatarsia were performed. One year after the operation, the callosity of the third toe resolved and the clinical scores were improved. In the case of a hallux valgus deformity with second dorsal dislocation of the toes, surgeons should consider that there are rare cases with second metatarsal shortening. When hallux valgus associated with second brachymetatarsia is diagnosed, second metatarsal lengthening should be considered in addition to hallux valgus surgery.

Delayed Onset of Infectious Foreign Body Granuloma for Nonabsorbable Sutures After Open Achilles Tendon Repair: A Case Report.

Foreign body granulomas from sutures are more common among non-absorbable sutures compared to absorbable sutures and have been reported as a postoperative complication in a variety of medical fields. However, only a few cases of delayed foreign body reaction have been reported and addressed with orthopedics. We present a patient with systemic lupus erythematosus who developed an infectious suture granuloma that extended to the entire Achilles tendon and was induced by nonabsorbable sutures that were used for open Achilles tendon repair 20 years before. This granuloma was resistant to antibiotic treatment and drainage and required surgical intervention. The tumor was marginally resected, and the continuity of the Achilles tendon was preserved. Histopathological examination detected many suture materials surrounded by xanthochromic necrotic lesions and the lesion was diagnosed as a foreign body granuloma. At 1 year after the operation, the patient did not exhibit exacerbation of infection or recurrence of the tumor, and she became able to walk by herself. To the best of our knowledge, this represents the first report of an infectious delayed foreign body granuloma in autoimmune disorder patient after open Achilles tendon repair. Surgical intervention should be considered, as treatment with conservative therapy such as antibiotics may be difficult.

Large osteochondral defect in the lateral femoral condyle reconstructed by Atelocollagen-associated autologous chondrocyte implantation combined with anterior cruciate ligament reconstruction.

BACKGROUND: Articular surface damage commonly associated with rupture of the anterior cruciate ligament (ACL). Large osteochondral defect, which consists of a severe depression fracture and a large cartilage defect, need to be treated due to deformation of the articular surface as it can impact the clinical outcome of ACL reconstruction. Although autologous chondrocyte implantation is one of the useful options in such cases, it can be questioned whether the reconstruction of the ACL and osteochondral defect should be performed in one procedure alone. CASE PRESENTATION: We report a case of a 38-year-old male with a deep depression fracture extending to the edge of the lateral femoral condyle associated with ACL injury after twisting his right knee while skiing. The patient was successfully treated with tissue-engineered cartilage transplantation covered by the periosteum with an iliac bone graft combined with anatomic double-bundle ACL reconstruction. Histopathological examination of the transplanted cartilage taken at second-look arthroscopy showed a cartilage-like tissue in the middle to deep zone in which the extracellular matrix was largely stained with Safranin O. The patient was able to return to his previous level of skiing activity without any experience of knee pain. Magnetic resonance imaging at 4 years after surgery showed that the graft integrated to the border zone and subchondral bone. The operated knee showed negative Lachman test and had a full range of motion. CONCLUSIONS: To our knowledge, this is the first report of anatomic double-bundle ACL reconstruction with tissue-engineered cartilage transplantation and an iliac bone graft to restore the lateral edge of the femoral condyle.

Correction osteotomy for bilateral varus knee deformity caused by premature epiphyseal closure induced by hypervitaminosis A: a case report.

BACKGROUND: A vitamin A derivative, 13-cis-retinoic acid (isotretinoin), has been administered to treat several types of pediatric cancer and has improved survival rates in patients despite being known to induce premature epiphyseal closure. As the number of patients treated by 13-cis-retinoic acid increases, demands for salvage treatment after systemic retinoid therapy are emerging. However, few studies have described the surgical treatment of this disease. CASE PRESENTATION: We report a case with bilateral varus knee deformity due to premature epiphyseal closure that occurred during treatment with isotretinoin for neuroblastoma. The patient was successfully treated with correction osteotomy using a Taylor spatial frame in the right knee joint and femoral closed wedge osteotomy using a locking plate in left knee joint. Histopathological examination of the growth plate showed polar irregularity of chondrocytes and decreased cartilage matrix without apoptosis. In contrast, arthroscopic findings showed an intact joint surface. No recurrence of varus deformity was evident on follow-up at 1 year. CONCLUSIONS: To the best of our knowledge, this represents the first report of correction osteotomy for varus knee deformity due to premature epiphyseal closure that occurred during treatment with isotretinoin.

Bone metastatic cancer of unknown primary at initial presentation.

INTRODUCTION: Cancer of unknown primary (CUP) is a challenging malignancy. The purpose of this study was to investigate the clinical characteristics and prognosis of bone metastatic CUP using the population-based Surveillance, Epidemiology, and End Results (SEER) database. METHODS: From the SEER database, we identified 1908 patients with bone metastatic CUP at initial presentation between 2010 and 2018. Histology was subdivided following International Classification of Diseases for Oncology codes as Adenocarcinoma, Squamous cell, Neuroendocrine, or Carcinoma not otherwise specified (NOS). Cox proportional hazard modeling was applied using factors of age, sex, ethnicity, histological subtype, and therapeutic intervention. RESULTS: Among the 1908 patients, histology was Neuroendocrine in 240 patients, Squamous cell in 201 patients, Adenocarcinoma in 810 patients and NOS in 657 patients. In each subtype, patients tended to be predominantly male and white. Chemotherapy was introduced for 28% of patients and radiation for 34% in the entire cohort. Survival in patients with bone metastatic CUP was unfavorable, with a median survival of 2 months. Among the histological subtypes, Adenocarcinoma showed shorter survival than the other groups. In addition, treatment interventions such as chemotherapy and radiation therapy prolonged survival, particularly for Squamous cell, Adenocarcinoma and NOS, but not for Neuroendocrine. DISCUSSION: Bone metastatic CUP showed extremely poor prognosis, but treatment interventions such as chemotherapy and radiation generally offered survival benefits. Further randomized clinical research is needed to confirm the present results.

Paradoxical Change in Subchondral Bone Density in the Medial Compartment of the Proximal Tibial Articular Surface After High Tibial Osteotomy: A Detailed Subchondral Bone Density Analysis.

BACKGROUND: High tibial osteotomy (HTO) aims to realign the varus knee to alleviate stress in the medial compartment. However, detailed information on the impact of HTO on stress distribution across the tibiofemoral joint surface still needs to be completely elucidated. PURPOSE/HYPOTHESIS: The present study aimed to analyze the subchondral bone density distribution to validate the alignment threshold causing paradoxical changes. We hypothesized that there would be a paradoxical stress change in the medial compartment beyond a specific threshold for lower limb realignment after HTO. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A retrospective clinical study of 32 knees from 30 patients who underwent medial opening-wedge HTO between 2015 and 2019 was conducted at Hokkaido University Hospital. The subchondral bone density across the tibiofemoral joint was analyzed using computed tomography-osteoabsorptiometry before and after HTO. The high-density area (HDA) within the medial and lateral compartments and their subregions, which were quartered in the coronal plane, was specifically examined. RESULTS: The hip-knee-ankle angle, medial proximal tibial angle (MPTA), joint line obliquity (JLO), and joint line convergence angle significantly changed after HTO (P < .01). The HDA of the medial compartment to the total HDA ratio decreased from 83% to 77%. Paradoxically, the HDA in the most central subregion of the medial compartment increased from 24% to 30%. There were significant differences between MPTA and JLO in patients with and without paradoxical changes in the HDA. MPTA and JLO cutoff values causing paradoxical changes in the HDA were 94° and 4°, respectively. CONCLUSION: There was a paradoxical stress increase in the M4 region at the medial compartment associated with the MPTA and JLO beyond specific thresholds. Therefore, surgical planning should be cautiously performed to prevent overcorrection, which can lead to adverse stress distribution changes.

Articular cartilage corefucosylation regulates tissue resilience in osteoarthritis.

This study aimed to investigate the glycan structural changes that occur before histological degeneration in osteoarthritis (OA) and to determine the mechanism by which these glycan conformational changes affect cartilage degeneration. An OA model was established in rabbits using mannosidase injection, which reduced high-mannose type N-glycans and led to cartilage degeneration. Further analysis of glycome in human OA cartilage identified specific corefucosylated N-glycan expression patterns. Inhibition of N-glycan corefucosylation in mice resulted in unrecoverable cartilage degeneration, while cartilage-specific blocking of corefucosylation led to accelerated development of aging-associated and instability-induced OA models. We conclude that α1,6 fucosyltransferase is required postnatally to prevent preosteoarthritic deterioration of articular cartilage. These findings provide a novel definition of early OA and identify glyco-phenotypes of OA cartilage, which may distinguish individuals at higher risk of progression.

Elucidation of the association between additional distal femoral resection and extension angle improvement following the actual surgical steps with the Robot-TKA system.

BACKGROUND: This study investigates the association between additional distal femoral resection and improved flexion contracture in total knee arthroplasty (TKA) with a robot-assisted system. Flexion contracture is a common issue in patients with knee osteoarthritis, which causes postoperative complications and functional limitations. This study aims to evaluate the effectiveness of additional bone resection in flexion contracture correction and knee extension angle improvement after the actual surgical steps. METHODS: The study included 11 patients who underwent posterior-stabilized (PS)-type TKA with a robot-assisted system. The surgical technique consisted of precise bone resection and range of motion evaluation using a navigation system. A precut technique was used to facilitate posterior access and remove osteophytes that cause the contracture. The amount of additional distal femoral resection was determined based on the thickness of the insert trial required for achieving full extension. RESULTS: The flexion contracture correction angle and the amount of additional distal femoral resection demonstrated a linear relationship. An average of 2.0° with the standard error (SE) of 0.6° improvement in flexion contracture was observed per 1.0 mm of additional bone resection. The postoperative evaluation demonstrated a significant improvement in knee extension angle, thereby reducing the contracture degree. CONCLUSION: This study was the first to perform the additional distal femoral resection on the living knee, which closely replicates the actual surgical steps. The current study revealed that an additional 1.0 mm of distal femoral resection in PS-type TKA improves knee extension angle by 2.0° (SE 0.6°) within an additional resection range of 1.0 mm to 3.3 mm.

The alterations in nerve growth factor concentration in plasma and synovial fluid before and after total knee arthroplasty.

Total knee arthroplasty (TKA) is an effective procedure for pain relief; however, the emergence of postsurgical pain remains a concern. In this study, we investigated the production of nerve growth factor (NGF) and mediators that affect NGF production and their function in the synovial fluid and plasma after TKA. This study included 19 patients (20 knees) who had rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and knee osteoarthritis (OA) who underwent TKA, categorized into OA and non-OA groups. The levels of NGF, inflammatory cytokines, and lipid mediators were analyzed before and after surgery. The intraoperative synovial fluid NGF concentration was more than seven times higher in the non-OA group than in the OA group. The intra-articular NGF levels increased significantly by more than threefold postoperatively in the OA group but not in the non-OA group. Moreover, the levels of inflammatory cytokines and lipid mediators were increased in the synovial fluid of both groups. The intra-articular cytokines or NGF concentrations positively correlated with postoperative pain. Targeted NGF control has the potential to alleviate postsurgical pain in TKA, especially in patients with OA, emphasizing the importance of understanding NGF dynamics under different knee conditions.