Idiopathic Osteonecrosis Research Articles

Hyaluronan in articular cartilage: Analysis of hip osteoarthritis and osteonecrosis of femoral head.

Hyaluronan (HA) plays crucial roles in the maintenance of high-quality cartilage extracellular matrix. Several studies have reported the HA in synovial fluid in patients with osteoarthritis (OA), but few have described the changes of HA in articular cartilage of OA or idiopathic osteonecrosis of the femoral head (ONFH). KIAA1199 was recently reported to have strong hyaluronidase activity. The aim of this study was to clarify the HA metabolism in OA and ONFH, particularly the involvement of KIAA1199. Immunohistochemical analysis of KIAA1199 and HA deposition was performed for human OA (n = 10), ONFH (n = 10), and control cartilage (n = 7). The concentration and molecular weight (MW) of HA were determined by competitive HA ELISA and Chromatography, respectively. Regarding HA metabolism-related molecules, HAS1, HAS2, HAS3, HYAL1, HYAL2, and KIAA1199 gene expression was assessed by reverse transcriptase polymerase chain reaction. Histological analysis showed the overexpression of KIAA1199 in OA cartilage, which was accompanied by decreased hyaluronic acid binding protein (HABP) staining compared with ONFH and control. Little KIAA1199 expression was observed in cartilage at the collapsed area of ONFH, which was accompanied by a slight decrease in HABPstaining. The messenger RNA (​​​​​mRNA) expression of HAS2 and KIAA1199 was upregulated in OA cartilage, while the mRNA expression of genes related to HA catabolism in ONFH cartilage showed mostly a downward trend. The MWof HA in OA cartilage increased while that in ONFH cartilage decreased. HA metabolism in ONFH is suggested to be generally indolent, and is activated in OA including high expression of KIAA1199. Interestingly, MW of HA in OA cartilage was not reduced.

Comparison Between Concentrated Autologous Bone Marrow Aspirate Transplantation as a Hip Preserving Surgery and Natural Course in Idiopathic Osteonecrosis of the Femoral Head.

PurposeThe purpose is to compare the therapeutic efficacy of concentrated autologous bone marrow aspirate transplantation (CABMAT) with that of observation alone for osteonecrosis of the femoral head (ONFH).MethodsThis single-center study included patients with idiopathic ONFH that were either treated with CABMAT (CABMAT group) or managed through observation alone (observation group) over a >2-year follow-up period. The Japanese Investigation Committee classification was used to diagnose and classify ONFH. The collapse rates for stages 1 and 2 ONFH (i.e., pre-collapse stages) and the THA conversion rates were compared between the CABMAT and observation groups.ResultsThe CABMAT and observation groups comprised 232 (mean follow-up: 8.2 years) and 106 (mean follow-up: 6.0 years) patients, respectively. No significant intergroup differences were noted in the stages, types, and associated factors of ONFH. The collapse rates for pre-collapse stages in the CABMAT and observation groups were 67.1% and 65.3%, respectively. For stage 1, the collapse rates were significantly lower in the observation group than in the CABMAT group (p<0.05). The overall THA conversion rates in the CABMAT and observation groups were 24.3% and 41.5%, respectively (p<0.0001). For ONFH of stages 3A and 3B (collapse stages), the THA conversion rates were significantly lower in the CABMAT group (p<0.05).ConclusionCollapse rates were significantly higher for stage 1 ONFH; for collapse stages, the THA conversion rates were significantly lower in the CABMAT group than in the observation group. Therefore, observation and CABMAT are recommended for ONFH of stage 1 and for ONFH of higher stages, respectively.

New alcohol-associated idiopathic osteonecrosis of the femoral head (ONFH) development in the contralateral hip after the alcohol-associated ONFH in the lateral hip. A case report

New alcohol-associated idiopathic osteonecrosis of the femoral head (ONFH) development in the contralateral hip after the alcohol-associated ONFH in the lateral hip. A case report

Clinical and genetic characteristics of Legg-Calve-Perthes disease

Legg-Calve-Perthes disease (LCPD) is a known childhood form of idiopathic femoral head osteonecrosis. It is characterized by a sequence of events involving the capital femoral epiphysis. The disease process is associated with the disruption of the blood supply to the femoral head. In most cases, LCPD appears in a sporadic form. Occurrences of cases in families have also been reported, with some families having more than two affected individuals. The disease etiology is still unknown, however, various factors have been considered for the pathogenesis of LCPD, including very low body weight or short stature at birth, maternal smoking, and secondhand smoke exposure. Interaction of multiple environmental and genetic factors has also been postulated as an underlying player in the development of the disorder. Hypercoagulability may have a major role in LCPD development. Families segregating LCPD largely demonstrate autosomal dominant inheritance. Variants in coagulations genes (Factor 5 and Factor 2) and collagen encoding gene (COL2A1) have been linked to the disease. However, our knowledge of the LCPD pathogenic factors is limited. A better understanding of the association between LCPD and causative factors, for example, the role of hypercoagulability in osteonecrosis development, might lead to the development of improved treatments, to shorten the acute phase of the disease during childhood as well as to possibly reduce the long-term effects of osteoarthritis in adulthood. Detection of large-effect variants underlying LCPD may help in offering extended screening for all first-degree family members. In this review, we would like to discuss the etiological factors underlying LCPD with special emphasis on the role of coagulation factors and mutations in the genes encoding those coagulation factors.

Bilateral stress fracture of the femoral neck in association with simultaneously developing osteonecrosis of the femoral head: a case report

BackgroundFemoral neck stress fractures are rare and often recognized as overuse injuries that occur in young athletes or military personnel. A case following osteonecrosis of the femoral head is quite rare; even more uncommon is its occurrence in the bilateral hips. Magnetic resonance imaging has been established as the preferred tool for diagnosing nondisplaced femoral neck stress fracture due to overuse injury. Magnetic resonance imaging was also useful to detect the initial lesion even in this case, although the etiology was different between overuse injury and insufficiency fracture.Case presentationA 41-year-old Japanese woman diagnosed with bilateral early stage idiopathic osteonecrosis of the femoral head was observed non-weight-bearing as much as possible using a stick. However, her pain and difficulty in walking progressed. Bilateral femoral neck stress fractures were subsequently detected by magnetic resonance imaging. The fracture initially appeared as a spot of bone marrow edema at the medial site of the femoral neck, and then developed into a fracture line. The patient underwent internal fixation of both hips with sliding hip screws to stabilize the stress fractures. In addition, the preparatory reaming served as core decompression of the femoral heads, as well as being treatment for osteonecrosis. Her bone mineral density and 25-hydroxy vitamin D values were low for her age. We administered eldecalcitol and teriparatide acetate. Her symptoms mostly improved, and the fracture lines and necrotic lesions on magnetic resonance imaging reduced at 5 months after the surgery.ConclusionsBilateral femoral neck stress fractures are a very rare condition and are often missed. It is important to listen to the patient’s complaints and perform an appropriate examination. We encountered a case of bilateral femoral neck stress fracture that occurred in a patient with early stage osteonecrosis of the femoral head, and were able to observe progression of stress fracture since before fracture occurred. This is considered to be the first report to capture imaging changes before and after the onset.

Is Stage 2 idiopathic osteonecrosis of the hip joint associated with version angles on imaging methods?

Objectives In this study, we aimed to investigate whether anatomical variations of acetabulum were associated to idiopathic osteonecrosis (ON) of the femoral head.Patients and methods Between January 2014 and March 2020, a total of 46 patients (32 males, 14 females; mean age: 43 years; range, 18 to 66 years) who were diagnosed with unilateral or bilateral ON of the hip joint and 44 healthy age- and sex-matched controls (30 males, 14 females; mean age: 46 years; range, 18 to 79 years) with no signs of ON of the hip joint were retrospectively analyzed. For both groups, measurements were taken of the anatomic parameters, including the acetabular version angle (VA), the sharp angle (SA), and the center-edge angle (CEA) on anteroposterior pelvic radiographs and magnetic resonance imaging (MRI) scans.Results The mean VA of both hips was found to be significantly smaller in Group 1 than in Group 2 on both MRI and X-ray (14.9±4.1 and 14.4±3.1 vs. 17.3±3.9 and 18.0±3.7, respectively; p=0.004, p<0.001). The mean SA of both hips was found to be significantly smaller in Group 1 than in Group 2 on both MRI and X-ray (39.0±2.9 and 38.9±2.8 vs. 41.6±3.9 and 40.8±4.9, respectively; p=0.001, p=0.036). The mean CEA of both hips was found to be significantly larger in ON group than in control group on both MRI and X-ray (36.7±6.1 and 36.9±7.0 vs. 32.0±6.0 and 31.5±7.5, respectively; p<0.001, p=0.001). Conclusion Version angles were found to be smaller in patients with ON and more acetabular coverage was observed. Greater coverage of the acetabulum may indicate early collapses of the femoral head even in Stage 2 ON patients. The smaller version angles may be associated with ON.

Osteoblast function in patients with idiopathic osteonecrosis of the femoral head : implications for a possible novel therapy.

AimsTo investigate whether idiopathic osteonecrosis of the femoral head (ONFH) is related to impaired osteoblast activities.MethodsWe cultured osteoblasts isolated from trabecular bone explants taken from the femoral head and the intertrochanteric region of patients with idiopathic ONFH, or from the intertrochanteric region of patients with osteoarthritis (OA), and compared their viability, mineralization capacity, and secretion of paracrine factors.ResultsOsteoblasts from the intertrochanteric region of patients with ONFH showed lower alkaline phosphatase (ALP) activity and mineralization capacity than osteoblasts from the same skeletal site in age-matched patients with OA, as well as lower messenger RNA (mRNA) levels of genes encoding osteocalcin and bone sialoprotein and higher osteopontin expression. In addition, osteoblasts from patients with ONFH secreted lower osteoprotegerin (OPG) levels than those from patients with OA, resulting in a higher receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) ligand (RANKL)-to-OPG ratio. In patients with ONFH, osteoblasts from the femoral head showed reduced viability and mineralized nodule formation compared with osteoblasts from the intertrochanteric region. Notably, the secretion of the pro-resorptive factors interleukin-6 and prostaglandin E2 as well as the RANKL-to-OPG ratio were markedly higher in osteoblast cultures from the femoral head than in those from the intertrochanteric region.ConclusionIdiopathic ONFH is associated with a reduced mineralization capacity of osteoblasts and increased secretion of pro-resorptive factors.Cite this article: Bone Joint Res 2021;10(9):619–628.

Role of combinations of polymorphisms of cytokine genes in the diagnosis of Legg–Calve–Perthes disease in children

Background. LeggCalvePerthes disease (LCPD) is an idiopathic avascular femoral head osteonecrosis. The early disease stage is associated with the development of synovitis of the hip joint linked to the overproduction of factors induced by hypoxia as well as of interleukin (IL)-6. Associations of individual polymorphic variants of cytokine genes with LCPD have been shown. Moreover, alterations in the cytokine regulatory cascade are considered an important link in the pathogenesis of synovial inflammation in the early stages of LCPD. Accordingly, this process may be associated with a certain combination of polymorphic variants of the genes for pro-inflammatory and anti-inflammatory cytokines.&#x0D; Aim. This study aimed to study the associations of polymorphic variants of the genes for pro-inflammatory and anti-inflammatory IL with LCPD.&#x0D; Materials and methods. In this casecontrol study, the main and control groups were composed of 26 children with LCPD and 40 healthy children (all aged 311 years), respectively. Genotyping of IL10 (rs1800896), IL13 (rs20541), IL18 (rs187238), IL18 (rs5744292), IL1a (rs1800587), IL1RA (POL_GF_58), IL-1Ra (rs4251961), IL1B (rs16944), IL1B (rs1143634), IL4 (POL_GF_59), IL4 (rs2243250), IL6 (rs1800796), IL6 (rs1800795), INF (rs2430561), TGF (rs1800469), and TNF (rs1800629) was performed by polymerase chain reaction (PCR) using TaqMan probes to the corresponding polymorphic variants of genes produced by Thermo Fisher Scientific (USA) on an amplifier ViiATM 7 RealTime PCR System (Life Technologies, USA). Statistical processing of the results was carried out using the SNPstats program and multifactor dimensionality reduction.&#x0D; Results. The study revealed three separate LCPD-potentiating genotypes of polymorphic variants of cytokine genes: IL10 (rs1800896; TC)*T/C (OR 6.50), IL4 (POL_GF_49, VNTR, Intron4)*2R/2R (OR 12.32), and IL-6 (rs1800796; GC)*G/C (OR 4.08). Two polymorphic variants of the IL4 gene (POL_GF_49, VNTR, Intron4, and rs2243250; CT) had a pronounced synergism with respect to the diagnosis of LCPD. Moderate synergy with respect to the diagnosis of LCPD demonstrated the intergenic interaction of IL6 (rs1800796, GC) with tumor necrosis factor- (rs1800629, GA). Moderate antagonism between LCPD and intergenic interactions was obtained for polymorphic variants of IL18 (rs5744292, TC) and transforming growth factor- (rs1800469, AG) genes.&#x0D; Conclusions. The pathogenesis of synovitis and subsequent osteonecrosis in LCPD is associated with a combination of polymorphic variants of the genes of pro-inflammatory and anti-inflammatory cytokines, as well as of DNA variants of the pro-allergic IL4 gene.

Plasminogen activator inhibitor-1 promoter sequence variations in idiopathic osteonecrosis of head of femur.

Background & objectives:Primary or idiopathic osteonecrosis of femur head (ONFH) is the second most commonly observed cause among Indian patients suffering from ischemic ONFH. Although a number of genetic polymorphisms have been associated with idiopathic ONFH pathogenesis in Korean and Chinese populations, there are no studies in the Indian population. This is an exploratory study designed to implicate in promoter sequence polymorphisms of a critical fibrinolytic system regulator, plasminogen activator inhibitor-1 (PAI-1) gene, in cases of idiopathic osteonecrosis. Promoter sequence variations can affect expression levels of PAI-1 gene and may disrupt the coagulation/fibrinolytic equilibrium, which may finally culminate into osteonecrosis. Hence, the aim of the study was to investigate the role of single-nucleotide polymorphisms (SNPs) in the promoter region of PAI-1 gene and osteonecrosis development.Methods:Two SNPs of the PAI-1 gene (rs2227631, -844 G/A; rs1799889, -675 4G/5G) were genotyped in 25 patients diagnosed with idiopathic ONFH and 25 control subjects, using direct sequencing. Subsequently, association analyses were performed for the genotyped SNPs.Results:Both the rs2227631 and rs1799889 genotype and allele frequencies of PAI-1 gene showed an insignificant association with osteonecrosis risk (P=0.717, 0.149). Haplotype frequencies of rs2227631 and rs1799889 were also calculated in patients having idiopathic ONFH and controls. Although the distribution of haplotype GA-4G 4G was found to be the highest among the cases, it was not significantly different when compared with the controls.Interpretation & conclusions:Our findings demonstrate that the minor alleles of promoter region sequences of the PAI-1 gene do not contribute to an increase in ONFH predisposition. However, this is a preliminary study and its findings should be considered as suggestive for studies to be done in a larger sample size.

A case of total talar replacement for idiopathic osteonecrosis of the talus

A case of total talar replacement for idiopathic osteonecrosis of the talus

The Clinical Result of Transtrochanteric Curved Varus Osteotomy for Idiopathic Osteonecrosis of the Femoral Head

The Clinical Result of Transtrochanteric Curved Varus Osteotomy for Idiopathic Osteonecrosis of the Femoral Head

A case of total hip arthroplasty for idiopathic osteonecrosis of the femoral head caused by Takayasu arteritis

A case of total hip arthroplasty for idiopathic osteonecrosis of the femoral head caused by Takayasu arteritis

Aseptic femur head necrosis revealing Cushing's disease: a rare presentation

Background: Cushing's disease is an endocrine disorder and may be associated with non-traumatic osteonecrosis of the hip. We report the case of avascular necrosis of the femoral heads (AVNFH) as the presenting manifestation of Cushing's disease. Case presentation: A 29-year-old male patient was referred to our department because of non-traumatic bilateral hip pain evolving for two years. The pain was associated with lameness when walking. He noticed a drop in libido since one year with erectile dysfunction. Physical examination revealed facio-truncal obesity, abdominal violaceous striae, dorsal hyper-kyphosis, a pain and limitation of internal rotation of the left hip with a Lequesne index of 16. The standard radiography showed a loss of sphericity of the left femoral head with an aspect of eggshell. The MRI confirmed the diagnosis of a bilateral AVNFH. The baseline cortisol level was 287 ng/ml. AVNFH as the presenting manifestation of Cushing's disease was suspected and confirmed by a pituitary MRI which revealed a pituitary adenoma. A discharge of the hips was indicated. The patient underwent surgical resection of the adenoma and was referred to the endocrinology department. The histopathological examination confirmed the diagnosis of pituitary adenoma (corticotrope adenoma). The patient has also received an intravenous perfusion of 5 mg of Zoledronic acid. The follow up was marked by the regression of the symptoms of Cushing's disease and the hip pain. Conclusion: AVNFH as the presenting manifestation of Cushing's disease is rarely described. Hence, it’s needed to exclude endogenous hypercorticism in any patient with idiopathic osteonecrosis.

Association of Neutrophil Extracellular Traps with the Development of Idiopathic Osteonecrosis of the Femoral Head

Idiopathic osteonecrosis of the femoral head (ONFH) is defined as necrosis of osteocytes due to a non-traumatic ischemia of the femoral head. Iatrogenic glucocorticoid administration and habitual alcohol intake are regarded as risk factors. It has been suggested that glucocorticoid-induced activation of platelets contributes to the local blood flow disturbance of the femoral head. Both activated platelets and alcohol can induce neutrophil extracellular traps (NETs). To determine the association of NETs with the development of idiopathic ONFH, surgically resected femoral heads of patients with idiopathic ONFH and osteoarthritis were assessed for existence of NET-forming neutrophils by immunofluorescence staining. NET-forming neutrophils were present in small vessels surrounding the femoral head of patients with idiopathic ONFH but not osteoarthritis. Moreover, Wistar-Kyoto rats were intravenously injected with NET-forming neutrophils or neutrophils without NET induction, and then the ischemic state of the tissue around the femoral head was evaluated by immunohistochemistry for hypoxia-inducible factor-1α. NET-forming neutrophils circulated into the tissue around the femoral head, and hypoxia-inducible factor-1α expression in the tissue was higher compared with that of rats intravenously administered with neutrophils without NET induction. Furthermore, ischemic change of osteocytes was observed in the femoral head of rats given an i.v. injection of NET-forming neutrophils. The collective findings suggest that NETs are possibly associated with the development of idiopathic ONFH.

Neck modularity in total hip arthroplasty: a retrospective study of nine hundred twenty-eight titanium neck implants with a maximum follow-up of eighteen years.

Neck modularity was introduced to improve total hip arthroplasty (THA) accuracy, but it has been associated with early breakages and corrosion issues. In our hospital, modular necks have been in clinical use since the 1990s. We retrospectively analysed the occurrence of these sequelae in implants placed between January 2000 and December 2014. Survival data from patients operatedon in our hospital were obtained from the regional arthroplasty registry (Registro dell'Impiantologia Protesica Ortopedica, RIPO). The cohort comprised 928 THAs on 908 patients. The average patient age was 67.8years. Main indications were primary osteoarthritis (71.4%), fracture (9.2%), congenital dysplasia or congenital luxation (7.8%), and idiopathic osteonecrosis (6.4%). All femoral stems were cementless, with 318 anatomically shaped (34.3%), 579 straight (62.4%), and 31 short stems (3.3%). All necks used were made of titanium alloy. The average follow-up time was 9.6years (range, 4-18years). In total, 66 revisions were reported. The main revision causes were periprosthetic fractures (33.3%), aseptic stem loosening (19.7%), luxation (18.2%), and implant breakage (12.1%). Five modular neck breakages were recorded. The overall survival rate was 87.7% at 17years. We did not observe any component corrosion. The neck breakage rate was 0.5%, and the luxation rate was 1.3%. Our experience suggests that neck modularity is a safe, effective way to reconstruct the proximal femur in THA patients. We attribute the absence of corrosion to the exclusive use of titanium necks.

Treatment of avascular osteonecrosis of femoral head by core decompression and platelet-rich plasma: a prospective not controlled study.

Core decompression is a surgical option since the 1960s for hip osteonecrosis treatment. This technique promotes bone repair by reducing intramedullary pressure, but this is not often enough to stop the progression of necrosis. The aim of this study was to associate core decompression with the regenerative stimulus provided by platelet-rich plasma (PRP) and compare our results with other regenerative techniques. Femoral head osteonecrosis was prospectively evaluated in 30 hips (22 patients, 15-60years) treated by core decompression and PRP graft. Patients presented monolateral or bilateral osteonecrosis in stage I-IIA-IIB according to Arlet and Ficat classification. The outcome was assessed by changes in Harris Hip Score (HHS) and the need for total hip replacement (THA). The mean preoperative HHS was 64 points, at two years from surgery was roughly 84 points. Sixteen of 30 hips showed osteonecrosis progression of the femoral head and were converted to THA. At the fiveyear follow-up, the survival rate was 100% for patients at stage I, 67% for stage IIA, and 0% for stage IIB and was 68% and 32% for idiopathic and secondary osteonecrosis, respectively. Core decompression combined with PRP could be indicated as a treatment for the I and IIA stages of osteonecrosis, as it significantly reduces joint pain and delays THA. This procedure should be avoided in AVNFH related to cortisone therapy because only a few benefits have been proven. It also has the advantage of being technically simple, minimally invasive, and free from complications.

Urinary miRNAs as biomarkers for idiopathic osteonecrosis of femoral head: A multicentre study.

ObjectivesUrinary microRNAs (miRNAs) have shown great diagnostic and prognostic values for multiple diseases. The profile of urinary miRNAs in patients with idiopathic osteonecrosis of femoral head (ONFH) is currently unclear.MethodsWe first randomly chose ten patients with each Association Research Circulation Osseous (ARCO) stage (I, II, III and IV) and ten healthy participants from the entire cohorts for initial screening. The miRNA polymerase chain reaction (PCR) array was then performed to identify the differentially abundant miRNAs in urine of these participants. We then verified the findings in the entire cohort. Clinical features including age, gender, bone mass index (BMI), lesion size and stages were recorded. We then analysed the association between the level of urinary miRNAs and clinical features.ResultsOur data indicated that there were 13 differentially abundant miRNAs among all groups. Urinary miR-150 demonstrated the highest diagnostic value among all candidates. Urinary miR-185 and miR-133a increased by ARCO staging. The levels of urinary miR-4824 abruptly decreased after femoral head collapse (ARCO stage III and IV). Urinary miR-144 was the only marker that correlated with lesion size.ConclusionsThe levels of urinary miRNAs are valuable biomarkers for idiopathic ONFH. Given the noninvasive nature of this test, it is potentially useful for diagnosis and monitoring of idiopathic ONFH progression.The translational potential of this articleThis article gives novel methods for ONFH diagnosis and progression monitoring in a convenient and non-invasive way.

Acetabular Anatomical Parameters in Patients With Idiopathic Osteonecrosis of the Femoral Head

BackgroundOsteonecrosis of the femoral head (ONFH) is an increasing worldwide health problem. However, about 30% of the patients are diagnosed with idiopathic ONFH, which means no underlying etiology is identified. We hypothesized that acetabular anatomical abnormalities might be related to idiopathic ONFH. MethodsThis retrospective, 1:2 matched, case-control study included 101 patients (136 hips) with idiopathic ONFH and 202 control subjects (404 hips) matched for age, gender, and body mass index who had no apparent radiographic hip pathologies. The anteroposterior pelvic X-rays of the patients and control subjects were used to measure the anatomical parameters including the center-edge angle, the sharp angle, the acetabular depth ratio (ADR), and the acetabular head index (AHI). ResultsWe found that hips with idiopathic osteonecrosis had less acetabular coverage, lower center-edge angle (28.3° vs 32.3°, P < .001), acetabular depth ratio (298.0 vs 306.4, P = .006), and acetabular head index (82.2 vs 85.8, P < .001), and higher sharp angle (39.7° vs 38.0°, P < .001), compared with the control subjects. The incidence of acetabular dysplasia was also higher in the idiopathic ONFH group than the control group. ConclusionLess acetabular coverage was found in hips with idiopathic osteonecrosis than the control subjects. Less acetabular coverage may be associated with the development of ONFH in East Asian population.

Ultra-Short Anatomic Uncemented Femoral Stem and Ceramic-on-Ceramic Bearing in Patients With Idiopathic or Ethanol-Induced Femoral Head Osteonecrosis

BackgroundLong-term result of the ultra-short anatomic cementless stem in the patients with idiopathic or ethanol-induced osteonecrosis of the femoral head has not been assessed. The aim of this study is to evaluate the long-term clinical, radiographic, computed tomography scan, and dual-energy X-ray absorptiometry scanning results, and survivorship of this specific femoral stem in patients with idiopathic or ethanol-induced femoral head osteonecrosis. MethodsTwo hundred fifty-six patients (335 hips) with an average age of 49.8 years (range 20-63) were enrolled in the current study. All patients underwent dual-energy X-ray absorptiometry scanning of the acetabulum and proximal femur preoperatively and at final follow-up. Computed tomography scan was obtained in all patients at final follow-up. The mean follow-up was 14.7 years (range 13-16). ResultsAt final follow-up, the average Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index score, and University of California, Los Angeles activity score were 94 points, 12 points, and 8 points, respectively. Four stems (1%) underwent revision for aseptic loosening. One acetabular component (0.3%) was revised for recurrent dislocation. No hip was revised for squeaking or clicking sound. Survivorship of the femoral stem was 99.0% (95% confidence interval 94-100) and that of the acetabular component was 99.4% (95% confidence interval 95-100) at 14.7 years. ConclusionUltra-short proximal loading anatomic uncemented femoral stems with ceramic-on-ceramic bearings have excellent survivorship free from aseptic loosening and good clinical results at long term. Level of EvidenceLevel IV

Diagnostic issue on spontaneous osteonecrosis of medial tibial plateau.

To the Editor: I read with great interest the recent report of Yang et al[1], “Clinical Characteristics and Treatment of Spontaneous Osteonecrosis of Medial Tibial Plateau: A retrospective case study” (published on November 5, 2018, Chin Med J, page 2544–2550), because there have been very few reports on isolated spontaneous medial tibial plateau osteonecrosis and little is known about osteonecrosis of the tibial plateau. I would like to comment on diagnostic issues in this letter. Osteonecrosis of the knee can be a devastating disease that leads to end-stage arthritis of the knee. The knee is the second most commonly affected site after the hip.[2] Spontaneous osteonecrosis of the knee (SPONK) involving medial femoral condyle was described as a distinct entity by Ahlback et al in 1968[3] and is also called idiopathic or primary osteonecrosis to distinguish it from secondary osteonecrosis, which is associated with corticosteroid therapy, blood dyscrasias, Gaucher disease, caisson disease,[4] and other rare conditions, for example, laser-assisted arthroscopic chondroplasty.[5] The condition usually involves a single condyle, most often the medial femoral condyle, affected in 94% of the cases and can also occur in the lateral femoral condyle or in the tibial plateaus.[6] Involvement of the tibial plateau, which was first reported in the French literature by d’Angelijan et al[7] in 1967 and was described in the English literature by Houpt et al[8] is less common. Only 2% of osteonecrosis around the knee may affect the tibial plateau. The medial tibial plateau is more frequently affected than the lateral.[9] Therefore, to our knowledge, it remains a rare cause of knee pain. In the article, the case group contains 22 patients in 15 months (from March 2015 to June 2016), it means real prevalence may be underestimated. Magnetic resonance imaging (MRI) is both sensitive and specific for recognizing SPONK of both medial femoral condyle and tibial plateau and recommended for detection of the disease, due to its high sensitivity in detecting bone marrow edema.[10] MRI characteristics include a diffuse area of hyperintensity widespread into the metaphysics on T2-weighted images, the focal subchondral area of low signal intensity adjacent to the subchondral bone plate on T1-weighted images and focal epiphyseal contour depressions. But the MRI-detected subchondral bone marrow lesion, comprised of fibrosis, necrosis, edema, and bleeding into fatty marrow in different proportions as well as abnormal trabeculae, is also a common finding in patients with OA.[11] In the article, the MRI images showed in Figures 2 and 5 have no typical MRI signs of spontaneous medial tibial plateau osteonecrosis, MRI T1 and T2 images show cartilage degeneration, narrow of joint space, focal bone marrow edema and formation of subchondral cysts in medial knee compartment. We think it is more likely anteromedial osteoarthritis of knee, not a typical SPONK of medial tibial plateau. Although medial unicompartmental knee arthroplasty is also appropriate surgical indication. We also noted that in the series, there are 17 patients (77%) with a Level III medial meniscus posterior root tears (MMPRT) and the lesions of 68% patients involved the central tibial plateau. Subchondral marrow edema deep to the MMPRT was described as a harbinger of meniscal root failure. Ipsilateral tibiofemoral compartment bone marrow edema and insufficiency fractures are commonly noted in the presence of posterior meniscal tears.[12] Therefore, differential diagnosis is important and the condition has not been clearly discussed. Funding This work was supported by a grant from Ministry of Science and Technology of China (No. 2017YFC0108003). Conflicts of interest None.