Structural properties and immune-enhancing activities of galactan isolated from red seaweed Grateloupia filicina.

A water-soluble polysaccharide (GFP) was isolated from Grateloupia filicina and fractionated using a DEAE Sepharose Fast Flow column to evaluate immunostimulatory activity. Carbohydrates (62.0%-68.4%) and sulfates (29.3%-34.3%) were the major components of GFP and its fractions (GFP-1 and GFP-2), with relatively lower levels of proteins (4.5%-15.4%) and uronic acid (1.4%-3.9%). The average molecular weight (Mw ) for GFP and its fractions was calculated between 98.2%-243.7 kDa. The polysaccharides were composed of galactose (62.1%-87.2%), glucose (4.5%-33.2%), xylose (3.1%-5.3%), mannose (1.4%-2.2%), rhamnose (1.2%-2.0%), and arabinose (0.9%-1.7%) units connected through →3)-Galp-(1→, →4)-Galp-(1→, →2)-Galp-(1→, →6)-Galp-(1→, →3,4)-Galp -(1→, →3,6)-Galp-(1→, →4,6)-Galp-(1→, →3,4,6)-Galp-(1→, →2,3)-Galp-(1→, →2,4)-Galp-(1→, →4)-Glcp-(1→, →6)-Glcp-(1→ and →4,6)-Glcp-(1→residues. The isolated polysaccharides effectively induced RAW264.7 murine macrophages by releasing nitric oxide (NO) and various cytokines via nuclear factor kappa light chain enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Further, the expression of toll-like receptor-2 (TLR-2) and TLR-4 in RAW264.7 cells indicated their activation through TLR-2 and TLR-4 binding receptors. Among the polysaccharides, GFP-1 highly stimulated the activation of RAW264.7 cells, which was mainly constituted of (→1) terminal-D-galactopyranosyl, (1→3)-linked-ᴅ-galactopyranosyl, (1→4)-linked-ᴅ-galactopyranosyl and (1→3,4) -linked-ᴅ-galactopyranosyl residues. These findings demonstrate that GFP-1 from G. filicina are effective at stimulating the immune system and this warrants further investigation to determine potential biomedical applications.

A novel sulfated mannan-carboxymethyl-5-fluorouracil-folic acid conjugates for targeted anticancer drug delivery.

CFP2 is a sulfated polysaccharide isolated from Codium fragile that shows excellent immunomodulatory activity. To reduce the side effects of 5-fluorouracil (5-FU), CFP2 was used as a macromolecular carrier to react with carboxymethyl-5-fluorouracil (C-5-FU) to form CFP2-C-5-FU, which further reacted with folic acid (FA) via an ester bond to form novel conjugates (CFP2-C-5-FU-FA). CFP2-C-5-FU-FA was confirmed by nuclear magnetic resonance (NMR) analysis. In vitro drug release results showed that the cumulative release rate of C-5-FU was 49.9% in phosphate buffer (pH 7.4) after 96 h, which was much higher than that of the other groups, indicating that CFP2-C-5-FU-FA showed controlled drug release behavior. CFP2-C-5-FU-FA also exhibited enhanced apoptosis and cellular uptake in vitro. Further, intravenous administration of CFP2-C-5-FU-FA in an HCT-116 cell-bearing xenograft mouse showed that the conjugates were safe and effective drug delivery systems. These results suggest that folate-targeted conjugates can be used effectively for efficient chemotherapy of colorectal cancer.

Myositis unrelated to the inoculation site after COVID-19 vaccination: a case report

We describe the case of a 49-year-old right hand-dominant woman with myositis of the biceps brachii muscle unrelated to the inoculation site following Pfizer-BioNTech COVID-19 vaccination on the deltoid muscle of the left shoulder. Coronavirus disease 2019 (COVID-19) pandemic has involved global spread, and different vaccines including inactivated, protein, vectored, and nucleic acid vaccines have been developed and administered. Common side effects of COVID-19 vaccines include general manifestations such as headache, fever, and fatigue, and various musculoskeletal symptoms. Here, we present a case of myositis occurring in the biceps brachii muscle unrelated to the inoculation site, which has not been reported previously, accompanied by a literature review.

Reliability of Measuring Leg Segments and Joint Angles Using Smartphones during Aquatic Exercise / 대한의료정보학회지

Objectives@#Aquatic therapy is a significant intervention method for both patients and healthy individuals. However, in clinical practice, quantitative measurements are rarely applied in aquatic therapy due to the disadvantages of submerging expensive instruments in water. In this study, we used readily available smartphones and armbands to measure leg segments and joint angles during aquatic gait and evaluated the reliability of these measurements. @*Methods@#Waterproof smartphones were strapped to the trunk, thighs, and shanks of 19 healthy young adults using armbands. The angles of the trunk, thigh, and shank segments were measured during aquatic gait. The measurements were repeated 1 day later. The data were analyzed to obtain the angles of the hip and knee joints. @*Results@#Measurement repeatability, calculated using the intraclass correlation coefficient (ICC), was the highest for the shank segment range of motion (ROM) (first 46.79° ± 5.50°, second 50.12° ± 9.98°, ICC = 0.78). There was high agreement in trunk segment ROM (first 6.36° ± 1.42°, second 4.29° ± 1.83°, ICC = 0.73), thigh segment ROM (first 33.49° ± 5.18°, second 37.31° ± 8.70°, ICC = 0.62), and knee joint ROM (first 52.43° ± 11.26°, second 62.19° ± 16.65°, ICC = 0.68) and fair agreement in hip joint ROM (first 34.60°±4.71°, second 37.80° ± 7.84°, ICC = 0.59). @*Conclusions@#Smartphones can be used to reliably measure leg segments and joint angles during aquatic gait, providing a simpler method for obtaining these measurements and enabling the wider use of aquatic motion analysis in clinical practice and research.

Electrocardiographic Abnormalities following Syncope during Warm-up in a Professional Football Player: A Case Report / 대한스포츠의학회지

We describe the case of a 32-year-old male professional football player experiencing syncope during a warm-up ahead of a regular professional football league match. Syncope recovered spontaneously, but an electrocardiogram test revealed T-wave inversion and upward convex ST elevation. Subsequent echocardiogram, angiography, exercise stress test, cardiac magnetic resonance imaging, and gene analysis showed no abnormalities. The athlete had no recurrence of chest pain or syncope during the treatment period of about 4 weeks, and there was no recurrence of symptoms until 6 months after returning to sports.

Metformin enhances the cytotoxic effect of nilotinib and overcomes nilotinib resistance in chronic myeloid leukemia cells

Nilotinib is used for treating patients with imatinib-sensitive or -resistant chronic myeloid leukemia (CML); however, nilotinib-resistant cases have been observed in recent years. In addition, a considerable number of patients receiving nilotinib developed diabetes. Metformin is a front-line drug for the treatment of type 2 diabetes, and several studies have shown that diabetes patients treated with metformin have reduced incidence of cancer. This study aimed to define the effect of metformin on CML cells to determine whether metformin overcomes nilotinib resistance, and to identify novel targets for the treatment of nilotinib resistance. Methods: We observed the effects of metformin and nilotinib on K562 and KU812 human CML cell lines. Nilotinib-resistant CML cell lines were generated by exposing cells to gradually increasing doses of nilotinib. Then, we investigated the driving force that makes resistance to nilotinib and the effect of metformin on the driving force. Results: Sub-toxic doses of metformin enhanced nilotinib efficacy by reducing Bcl-xL expression, which induces apoptosis in CML cells. Next, we generated nilotinib-resistant K562 and KU812 cell lines that overexpressed the c-Jun N-terminal kinase (JNK) gene. JNK silencing by a JNK inhibitor restored sensitivity to nilotinib. Furthermore, metformin was effective in decreasing phosphorylated JNK levels, restoring nilotinib sensitivity. Combined treatment with nilotinib and metformin was more effective than combined treatment with nilotinib and a JNK inhibitor in terms of cell proliferation inhibition. Conclusions: This study suggested that combination therapy with metformin and nilotinib may have clinical benefits of enhancing antileukemia efficacy and overcoming resistance to nilotinib.

Electrocardiographic Abnormalities following Syncope during Warm-up in a Professional Football Player: A Case Report / 대한스포츠의학회지

We describe the case of a 32-year-old male professional football player experiencing syncope during a warm-up ahead of a regular professional football league match. Syncope recovered spontaneously, but an electrocardiogram test revealed T-wave inversion and upward convex ST elevation. Subsequent echocardiogram, angiography, exercise stress test, cardiac magnetic resonance imaging, and gene analysis showed no abnormalities. The athlete had no recurrence of chest pain or syncope during the treatment period of about 4 weeks, and there was no recurrence of symptoms until 6 months after returning to sports.

Poorer dynamic postural stability in patients with anterior cruciate ligament rupture combined with lateral meniscus tear than in those with medial meniscus tear

Background@#Only limited data are available regarding postural stability between anterior cruciate ligament (ACL)-injured patients with medial meniscus (MM) tear and those with lateral meniscus (LM) tear. The purpose of this study was to compare preoperative postural stability for both involved and uninvolved knees in ACL rupture combined with MM and LM tears. It was hypothesized that there would be a significant difference in postural stability between these two groups. @*Methods@#Ninety-three ACL-injured patients (53 combined with MM tears vs. 40 combined with LM tears) were included. Static and dynamic postural stability were evaluated with the overall stability index (OSI), anterior– posterior stability index (APSI), and medial–lateral stability index (MLSI) using stabilometry. Knee muscle strength was evaluated using an isokinetic testing device. @*Results@#In the static postural stability test, none of the stability indices showed significant differences between the two groups for both knees (p > 0.05). In the dynamic postural stability test for involved side knees, the OSI and APSI were significantly higher in the LM tear group compared to the MM tear group (OSI: 2.0 ± 0.8 vs. 1.6 ± 0.5, p = 0.001; APSI:1.5 ± 0.6 vs. 1.3 ± 0.5, p = 0.023), but not the MLSI ( p > 0.05). In the static and dynamic postural stability tests in each group, there were no significant differences between the involved and uninvolved side knees ( p > 0.05). There was no significant difference in the knee muscle strength between the two groups ( p > 0.05). All postural stability showed no significant correlation with knee muscle strength ( p > 0.05). @*Conclusion@#Dynamic postural stability was poorer in patients with ACL rupture combined with LM tear than in those with MM tear. Therefore, close monitoring for postural stability would be necessary during preoperative and postoperative rehabilitation, especially for patients with ACL rupture combined with LM tear.Level of evidence: Level III:

Arthroscopic Treatment of Popliteal Cysts with and without Cystectomy: A Systematic Review and Meta-Analysis

PURPOSE: To compare the clinical outcomes of the arthroscopic treatments for popliteal cysts with and without cystectomy. METHODS: PubMed/MEDLINE, EMBASE, KoreaMed, and Cochrane Library were searched from the earliest available date of indexing through August 2016. The methodological quality of all articles was assessed according to the Coleman methodology score (CMS). Studies were grouped according to the surgical method, and a meta-analysis was conducted to identify the unsuccessful clinical outcome and complication rates. RESULTS: Nine studies were included; the mean CMS was 67.33 (standard deviation, 8.75 points). Cystectomy was reported in five studies; cystectomy was not performed in four studies. The odds ratio of unsuccessful clinical outcomes evaluated by Rauschning and Lindgren score was 122.05 (p<0.001) with cystectomy and 58.12 (p<0.001) without cystectomy. The effect size of complications was 0.16 (p<0.001) with cystectomy and 0.03 (p<0.001) without cystectomy. The recurrence rate was 0% with cystectomy and 6.4% without cystectomy. CONCLUSIONS: All the currently available studies showed satisfactory outcomes in both with and without cystectomy groups. However, arthroscopic cystectomy concurrently performed with management of intra-articular lesions was associated with a relatively low recurrence rate and a relatively high incidence of complications.

The Correlation Between Clinical Characteristics and Radionuclide Salivagram Findings in Patients With Brain Lesions: A Preliminary Study

OBJECTIVE: To evaluate the correlation between radionuclide salivagram findings and clinical characteristics in dysphagic patients with brain lesions. METHODS: The medical records of 35 dysphagic patients with brain lesions who simultaneously underwent both a videofluoroscopic swallowing study (VFSS) and radionuclide salivagram were analyzed retrospectively. The subjects were divided into two groups according to the presence of aspiration on a salivagram (group A, patients with aspiration on the salivagram; group B, patients with no aspiration on the salivagram). The differences between clinical characteristics and VFSS findings (penetration-aspiration scale [PAS]) between the two groups were analyzed. RESULTS: Eleven out of 35 patients displayed salivary aspiration on the radionuclide salivagram. There were no significant differences between the two groups according to age, sex, disease duration, PAS on VFSS and feeding methods (p≥0.05). The incidence of aspiration pneumonia was significantly higher in group A. In a multivariate logistic regression analysis with forward stepwise method, the Mini-Mental State Examination (MMSE) score was the only significant parameter in predicting positive findings in salivagrams (odds ratio=0.760; 95% confidence interval [CI], 0.625–0.923; p=0.006). The area under the receiver operating characteristic curve (AUC) of the MMSE score for positive detection in salivagrams was 0.855 (95% CI, 0.689–0.953; p < 0.0001). The optimal cut-off value was 7 for the MMSE score (sensitivity 72.73%, specificity 100%). CONCLUSION: In patients with brain lesions who complain of dysphagia, the MMSE score was correlated with salivary aspiration. If patients present with a score of 7 or less on the MMSE, performing a radionuclide salivagram may helpful for early detection of patients at high risk of aspiration pneumonia induced from salivary aspiration.

The Correlation Between Clinical Characteristics and Radionuclide Salivagram Findings in Patients With Brain Lesions: A Preliminary Study

OBJECTIVE: To evaluate the correlation between radionuclide salivagram findings and clinical characteristics in dysphagic patients with brain lesions. METHODS: The medical records of 35 dysphagic patients with brain lesions who simultaneously underwent both a videofluoroscopic swallowing study (VFSS) and radionuclide salivagram were analyzed retrospectively. The subjects were divided into two groups according to the presence of aspiration on a salivagram (group A, patients with aspiration on the salivagram; group B, patients with no aspiration on the salivagram). The differences between clinical characteristics and VFSS findings (penetration-aspiration scale [PAS]) between the two groups were analyzed. RESULTS: Eleven out of 35 patients displayed salivary aspiration on the radionuclide salivagram. There were no significant differences between the two groups according to age, sex, disease duration, PAS on VFSS and feeding methods (p≥0.05). The incidence of aspiration pneumonia was significantly higher in group A. In a multivariate logistic regression analysis with forward stepwise method, the Mini-Mental State Examination (MMSE) score was the only significant parameter in predicting positive findings in salivagrams (odds ratio=0.760; 95% confidence interval [CI], 0.625–0.923; p=0.006). The area under the receiver operating characteristic curve (AUC) of the MMSE score for positive detection in salivagrams was 0.855 (95% CI, 0.689–0.953; p < 0.0001). The optimal cut-off value was 7 for the MMSE score (sensitivity 72.73%, specificity 100%). CONCLUSION: In patients with brain lesions who complain of dysphagia, the MMSE score was correlated with salivary aspiration. If patients present with a score of 7 or less on the MMSE, performing a radionuclide salivagram may helpful for early detection of patients at high risk of aspiration pneumonia induced from salivary aspiration.

Diagnosis and Treatment of Discoid Meniscus

There is a greater incidence of discoid meniscus in Asian countries than in Western countries, and bilateral discoid menisci are also common. The discoid meniscus may be a congenital anomaly, and genetics or family history may play a role in the development of discoid menisci. Because the histology of discoid meniscus is different from that of normal meniscus, it is prone to tearing. Individuals with a discoid meniscus can be asymptomatic or symptomatic. Asymptomatic discoid menisci do not require treatment. However, operative treatment is necessary if there are symptoms. Total meniscectomy leads to an increased risk of osteoarthritis. Therefore, total meniscectomy is generally reserved for rare unsalvageable cases. Partial meniscectomy (saucerization) with preservation of a stable peripheral rim combined with or without peripheral repair is effective, and good short-, mid-, and long-term clinical results have been reported.

Uncommon Primary Synovial Chondromatosis Involving Only the Infrapatellar Fat Pad in an Elderly Patient

Primary synovial chondromatosis is a rare condition of idiopathic synovial chondrometaplasia and usually occurs during the third to fifth decades of life. Conversely, secondary synovial chondromatosis results from the growth of separated particles from articular cartilage or osteophytes in patients with joint diseases, such as degenerative osteoarthritis, and occurs mostly in elderly people. We describe here a 76-year-old male histopathologically confirmed as having primary synovial chondromatosis with no calcification of the infrapatellar fat pad (IFP) of the knee joint. To our knowledge, this is the first description of primary synovial chondromatosis of the knee joint confined to the IFP in a patient >60 years old.

Anion Transport or Nucleotide Binding by Ucp2 Is Indispensable for Ucp2-Mediated Efferocytosis.

Rapid and efficient engulfment of apoptotic cells is an essential property of phagocytes for removal of the large number of apoptotic cells generated in multicellular organisms. To achieve this, phagocytes need to be able to continuously uptake apoptotic cells. It was recently reported that uncoupling protein 2 (Ucp2) promotes engulfment of apoptotic cells by increasing the phagocytic capacity, thereby allowing cells to continuously ingest apoptotic cells. However, the functions of Ucp2, beyond its possible role in dissipating the mitochondrial membrane potential, that contribute to elevation of the phagocytic capacity have not been determined. Here, we report that the anion transfer or nucleotide binding activity of Ucp2, as well as its dissipation of the mitochondrial membrane potential, is necessary for Ucp2-mediated engulfment of apoptotic cells. To study these properties, we generated Ucp2 mutations that affected three different functions of Ucp2, namely, dissipation of the mitochondrial membrane potential, transfer of anions, and binding of purine nucleotides. Mutations of Ucp2 that affected the proton leak did not enhance the engulfment of apoptotic cells. Although anion transfer and nucleotide binding mutations did not affect the mitochondrial membrane potential, they exerted a dominant-negative effect on Ucp2-mediated engulfment. Furthermore, none of our Ucp2 mutations increased the phagocytic capacity. We conclude that dissipation of the proton gradient by Ucp2 is not the only determinant of the phagocytic capacity and that anion transfer or nucleotide binding by Ucp2 is also essential for Ucp2-mediated engulfment of apoptotic cells.

Unstable Simple Elbow Dislocation Treated with the Repair of Lateral Collateral Ligament Complex

BACKGROUND: Unstable simple elbow dislocation (USED) repair is challenged by the maintenance of joint reduction; hence, primary repair or reconstruction of disrupted ligaments is required to maintain the congruency and allow early motion of the elbow. We evaluated the effectiveness and the outcome of lateral collateral ligament (LCL) complex repair with additional medial collateral ligament (MCL) repair in cases of USED. METHODS: We retrospectively reviewed 21 cases of diagnosed USED without fractures around the elbow that were treated with primary ligament repair. In all cases, anatomical repair of LCL complex with or without common extensor origin was performed using suture anchor and the bone tunnel method. Next, the instability and congruency of elbow for a full range of motion were evaluated under the image intensifier. MCL was repaired only if unstable or incongruent elbow was observed. Clinical outcomes were evaluated using the Mayo elbow performance score (MEPS) and radiographic outcomes on last follow-up images. RESULTS: All cases achieved a stable elbow on radiographic and clinical results. LCL complex repair alone was sufficient to obtain the stable elbow in 17 of 21 cases. Four cases required additional MCL repair after restoration of the LCL complex. The overall mean MEPS was 91 (range, 70 to 100): excellent in 12 cases, good in 7 cases, and fair in 2 cases. All 17 cases with LCL complex repair only and 2 of 4 cases with additional MCL repair had excellent or good results by MEPS. CONCLUSIONS: USED requires surgical treatment to achieve a congruent and stable joint. If the repair of lateral stabilizer such as LCL complex acquires enough joint stability to maintain a full range of motion, it may not be necessary to repair the medial stabilizer in all cases of USED.

Diagnosis and Current Trends of Medial Meniscus Posterior Root Tear / 대한정형외과학회잡지

Medial meniscal root tears with extrusion result in the loss of transmission of circumferential hoop stresses, leading to significantly increased tibiofemoral contact pressure and changes in knee biomechanics and kinematics. Therefore, medial meniscal root tears have attracted attention in recent years with regard to their early diagnosis. With the remarkable development of magnetic resonance imaging and arthroscopy, early diagnosis of medial meniscal root tears is on the rise. This report includes diagnosis and current trends of medial meniscal root tears.

Lack of Correlation between Dynamic Balance and Hamstring-to-Quadriceps Ratio in Patients with Chronic Anterior Cruciate Ligament Tears

PURPOSE: The purpose of this study was to evaluate the quadriceps and hamstring muscle strength and hamstring-to-quadriceps (HQ) ratio, as well as the relationships of these parameters with dynamic balance, in patients with anterior cruciate ligament (ACL) rupture. MATERIALS AND METHODS: We compared 25 patients diagnosed with chronic unilateral ACL tears and 25 age-matched healthy volunteers. The maximal torque of the quadriceps and hamstring and dynamic balance were measured. RESULTS: Although the isokinetic maximal peak torques were about 50% lower in the quadriceps (57%, p<0.001) and hamstring (56%, p=0.001) muscles in the chronic ACL tear group than in the control group, their HQ ratios were similar (56%+/-17% vs. 58%+/-6%, p=0.591). HQ ratio was significantly correlated with anterior-posterior stability index (r=-0.511, p=0.021) and overall stability index (r=-0.476, p=0.034) in control group, but these correlations were not observed in chronic ACL tear group. CONCLUSIONS: Thigh muscle strength was about 50% lower in the chronic ACL tear group than in the control group, but the HQ ratio was similar. The dynamic balance of the knee was not influenced by thigh muscle strength but was influenced by HQ ratio in healthy young individuals. However, HQ ratio was not correlated with dynamic knee balance in chronic ACL tear patients.

Results of Gender-Specific Total Knee Arthroplasty: Comparative Study with Traditional Implant in Female Patients

PURPOSE: To compare the incidence of overhang between two distinct femoral components and whether there is clinical and radiological benefit of gender-specific implants in short-term follow-up. MATERIALS AND METHODS: One hundred and four knees in consecutive 66 female patients who underwent primary total knee arthroplasty due to primary osteoarthritis were included in this study. Overhang was measured and recorded in every cut surface of femur with both gender-specific and traditional trial femoral components respectively in every patient. Then, the knees were divided into two groups according to the type of the permanent femoral component they received. Clinical and radiological outcomes were compared between 2 groups at minimum 3 years after operation. RESULTS: Mean follow-up duration was 41.3 months (range, 36 to 50 months). Sixty two knees (59.6%) showed femoral overhang at least in one area with a traditional trial component, while 26 knees (25.0%) did with a gender-specific trial component (p<0.001). In terms of range of motion, Hospital for Special Surgery knee score, radiographic result, patella tilt angle and displacement, no significant difference was observed between two groups. CONCLUSIONS: The use of gender-specific implants substantially reduced the incidence of femoral overhang but did not demonstrate any clinical, functional or radiologic benefit in short-term follow-up.

Arthroscopic Burring of Exposed Cement Following Curettage and Cavity Filling Cementation for Chondroblastoma of the Proximal Tibia

Chondroblastoma of the proximal tibia is difficult to treat because of its epiphyseal predilection. This condition can be treated by curettage, which results in immediate restoration of stability and a reduced recurrence rate, followed by cement filling of the bone defect. Nevertheless, contact with cement can damage articular cartilage, potentially leading to severe knee osteoarthritis. Most previous reports regarding this complication described patients with giant cell tumors of the proximal tibia. We present here a patient who underwent arthroscopic treatment for cement exposure caused by articular cartilage loss of the tibial plateau, which occurred after initial curettage and cementation for chondroblastoma of the proximal tibia. To our knowledge, this is the first report on arthroscopic treatment of this condition.

Artificial Fusion of Infected Total Knee Arthroplasty Using a Flexible Intramedullary Rod Bundle and an Antibiotic-Loaded Cement Spacer / 대한정형외과학회잡지

Multiple total knee arthroplasty (TKA) failure resulting from a recurrent infection is a challenging problem. Knee arthrodesis is one treatment option that normally involves the application of an external fixator, plate fixation, and intramedullary nailing. However, these approaches are not always successful, and a reinfection is a risk, particularly in older, medically compromised patients. This paper reports a new arthrodesis technique that uses a bundle of flexible intramedullary rods and an antibiotic-loaded cement spacer. This technique was used in two cases of multiple TKA failure that resulted from a recurrent infection. The procedure was successful in both cases with no evidence of rod or cement failure. Two advantages of this procedure are infection eradication and mechanical strength. However, this procedure should only be used for medically compromised elderly patients at high risk of rerevision TKA failure resulting from persistent periprosthetic infection because rod fracture or loosening can occur with time.