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There are currently no reports on the clinical outcomes after total hip arthroplasty (THA) with previous curved periacetabular osteotomy (CPO), although the outcomes after THA with non-CPO types of periacetabular osteotomy have been reported. This study aimed to clarify the differences in clinical outcomes and radiographic features after THA with or without previous CPO. We performed a retrospective case–control with individual matching study. The participants were 10 patients with 11 hips that underwent cementless THA between October 1998 and October 2018 with previous CPO (osteotomy group). For the control group, we matched age, sex, and follow-up period, and included 32 patients with 33 hips that underwent cementless THA without previous CPO at a 1:3 ratio. The Harris Hip Score (HHS), cup size, position, and alignment, global offset (GO), operative time, perioperative blood loss, frequency of osteophyte removal, and major complications were compared between the two groups. The osteotomy group had no cases with revision surgery and dislocation. No significant differences were found between the two groups as follows: mean HHS, 94.9 points in the osteotomy group versus 92.7 points in the control group at the final follow-up; mean GO, 70.1 mm in the osteotomy group versus 71.4 mm in the control group; cup size, position, and alignment after THA; operative time; and perioperative blood loss. The frequency of osteophyte removal was higher in the osteotomy group. The take-home messages were that the clinical outcomes, including HHS, and radiographic features, including GO, after THA were equivalent in the two groups.

Background Curved periacetabular osteotomy (CPO) is performed via an anterior approach without detachment of the hip abductor muscles. This study aimed to evaluate the abductor muscle status shortly after CPO on magnetic resonance imaging (MRI). Methods We prospectively evaluated 38 hips in 38 patients 1 week and 3 months after CPO between October 2017 and July 2019. The status of the abductor muscles was assessed on MRI using the following criteria: grade 0, normal; grade I, strain/edema; grade II, partial tear; and grade III, complete tear. We also evaluated associations between muscle status and patients’ characteristics. Results One week after CPO, the gluteus maximus was classified as grade 0 in all patients. The gluteus medius was grade 0 in 84.2% of patients and grade I in 15.8%. The gluteus minimus was grade I in 55.3% of patients and grade II in 44.7%. Three months after CPO, both the gluteus maximus and gluteus medius were grade 0 in all patients, while the gluteus minimus was still grade I in 47.4%. There were no significant differences between patients with a grade 0 and grade I gluteus minimus at 3 months after CPO in patients’ characteristics (age and body mass index) or clinical scores (Harris Hip Score and Japanese Orthopedics Association score). Conclusion Both the gluteus minimus and medius showed abnormal appearances on MRI 1 week after CPO, whereas only the gluteus minimus showed abnormalities 3 months after CPO. This abductor muscle status did not affect the postoperative Harris Hip Score or Japanese Orthopedics Association score.

Pubic nonunion after curved periacetabular osteotomy (CPO) reportedly occurs in 1%-17% of patients and causes pubic pain in 21%. Furthermore, pubic nonunion is associated with a risk of ischial ramus stress fracture, but the mechanical influence of pubic nonunion has not been fully clarified.Patient-specific finite element (FE) analysis was performed using Mechanical Finder software. Three FE models (pre-CPO, union, and nonunion models) were constructed from preoperative and postoperative computed tomographic data. The contact area (mmPatient-specific FE models were generated using 18 consecutive hips treated with CPO. The mean contact pressure in the hip joint was not significantly different between the union and nonunion models (0.50 ± 0.10 vs 0.50 ± 0.09 MPa, P = .88). However, the mean equivalent stress at the ischial ramus in the nonunion models was 1.7 times higher than that in the union models (1.13 ± 0.77 vs 0.64 ± 0.45 MPa, P.01).FE analysis revealed that pubic nonunion did not affect the mechanical distribution in the hip joint itself but increased the mean equivalent stress at the ischial ramus. This finding suggests the importance of achieving pubic union after CPO to avoid the risk of ischial ramus stress fracture.

Background Curved periacetabular osteotomy (CPO) is a joint-preservation surgery to treat acetabular dysplasia. It is performed via an anterior approach with the osteotomy of the anterosuperior iliac spine (ASIS). One of the complications associated with CPO includes non-union of the osteotomy sites. However, all osteotomy sites including the ASIS have not been simultaneously evaluated. Therefore, we investigated: (1) the bone union status of all osteotomy sites; and (2) the predictors of non-union at one year after CPO based on computed tomography (CT). Hypothesis The bone union status may be different in each osteotomy site. Patients and methods This retrospective review included 147 hips of 124 patients with symptomatic acetabular dysplasia who underwent CPO from 2011 to 2018. At one year postoperatively, we evaluated the bone union status of all osteotomy sites: the ASIS, ischium, pubis, and ilium using CT and investigated the predictors for achieving bone union. Results Bone union was confirmed in both the ASIS and ilium in all cases. In contrast, ischial and pubic non-union was confirmed 15/147 hips (10.2%) and 42/147 hips (28.5%), respectively. The multivariate analysis revealed that the predictors of ischial non-union were both large width of the gap at the pubic osteotomy site and small postoperative acetabular roof obliquity, and that the predictor of pubic non-union was large width of the gap at the pubic osteotomy site. Discussion At one year after CPO, both the ASIS and ilium obtained complete bone union, while ischial and pubic non-union were observed. Large width of the gap at the pubic osteotomy site was the predictor of both ischial and pubic non-union. In CPO, sufficient bone union can be achieved at the ASIS and the ilium, while it is necessary to reduce the width of the gap at the pubic osteotomy site to prevent ischial and pubic non-union. Level of evidence IV; retrospective study.

Background Curved periacetabular osteotomy (CPO) is a joint-preservation surgery to treat acetabular dysplasia. It is performed via an anterior approach with the osteotomy of the anterosuperior iliac spine (ASIS). One of the complications associated with CPO includes non-union of the osteotomy sites. However, all osteotomy sites including the ASIS have not been simultaneously evaluated. Therefore, we investigated: (1) the bone union status of all osteotomy sites, and (2) the predictors of non-union at one year after CPO based on computed tomography (CT). Hypothesis The bone union status may be different in each osteotomy site. Patients and Methods This retrospective review included 147 hips of 124 patients with symptomatic acetabular dysplasia who underwent CPO from 2011 to 2018. At one year postoperatively, we evaluated the bone union status of all osteotomy sites: the ASIS, ischium, pubis, and ilium using CT and investigated the predictors for achieving bone union. Results Bone union was confirmed in both the ASIS and ilium in all cases. In contrast, ischial and pubic non-union was confirmed 15/147 hips (10.2 %) and 42/147 hips (28.5 %), respectively. The multivariate analysis revealed that the predictors of ischial non-union were both large width of the gap at the pubic osteotomy site and small postoperative acetabular roof obliquity, and that the predictor of pubic non-union was large width of the gap at the pubic osteotomy site. Discussion At one year after CPO, both the ASIS and ilium obtained complete bone union, while ischial and pubic non-union were observed. Large width of the gap at the pubic osteotomy site was the predictor of both ischial and pubic non-union. In CPO, sufficient bone union can be achieved at the ASIS and the ilium, while it is necessary to reduce the width of the gap at the pubic osteotomy site to prevent ischial and pubic non-union. Level of evidence IV; retrospective study.

The patella is a rare site for the development of primary tumors. This is the case report of a giant cell tumor (GCT) occurring in the patella in a 25-year-old woman. The patient presented with a 1-year history of occasional right anterior knee pain. The radiological characteristics suggested a benign condition. The intraoperative pathological diagnosis was GCT of the bone. The lesion was treated by radical curettage with adjuvant therapy comprising phenol and ethanol and injection of calcium phosphate cement. Histologically, the tumor consisted of round or spindle-shaped mononuclear cells admixed with numerous osteoclastic giant cells. The patient was asymptomatic and there was no evidence of local recurrence or distant metastasis 16 months after surgery. Although rare, patellar GCT may be included in the differential diagnosis of anterior knee pain and/or swelling, particularly in young adults.

Chemical burns from Hydrofluoric Acid (HFA) are poorly recognized, even though we sometimes encounter patients affected by these burns. HFA can cause lethal arrhythmia due to hypocalcemia and hypomagnesemia, particularly in cases of high-concentration HFA exposure. A 57-year-old man received lower body injuries from splashes of 50% HFA solution by an accident. He was transferred to our hospital by a helicopter emergency medical service (Doctor Heli). 10 mL of calcium gluconate solution (8.5% calcium gluconate) had been already administered before arrival to the emergency room. However, hypocalcemia was prolonged, fatal arrhythmia appeared, and we started the continuous administration of calcium gluconate. We amputated his leg in order to prevent systemic spreading of HFA. Further, we administered a massive transfusion of saline with catecholamine for the treatment of shock. However, the patient died after 7 hrs. In many reported cases of exposure to high-concentration HFA, death from fatal arrhythmia occurred within 1hr. Our patient was able to survive for 7 hrs, perhaps because of the early and intensive administration of calcium formulation and intensive care. This case serves as a warning to persons handling HFA, emergency physicians and dermatologists, who should recognize the corrosive nature and the potential risks of HFA to avoid tragic outcomes.