Corticosteroid-associated osteonecrosis of the femoral head in an 87-year-old patient following treatment for COVID-19-associated pneumonia: A case report.

Coronavirus disease 2019 is known to cause severe acute respiratory syndrome, and serious cases need to be treated with corticosteroids. Herein, we report an 87-year-old woman who developed bilateral osteonecrosis of the femoral head after corticosteroid treatment for coronavirus disease 2019-related pneumonia. Sixteen months after treatment, she developed right hip pain without any evidence of trauma. A diagnosis of bilateral osteonecrosis of the femoral head was made based on sclerotic bands on plain radiographs and low-signal bands on T1-weighted magnetic resonance images. The patient underwent right total hip arthroplasty 4 months after symptom onset. Histological examination of the resected femoral head revealed pathological evidence of osteonecrosis. The postoperative course was good, and the patient can now walk unassisted. To the best of our knowledge, this is the first report of histologically proven osteonecrosis after corticosteroid therapy for coronavirus disease 2019-related disease.

Assessment of the Hip Flexor Muscles Shortly after Curved Periacetabular Osteotomy using Magnetic Resonance Imaging.

BACKGROUND: Curved periacetabular osteotomy requires detachment and retraction of the hip flexors. In this study, we evaluated hip flexor muscle status by magnetic resonance imaging (MRI) shortly after curved periacetabular osteotomy. METHODS: We retrospectively evaluated 60 hips of 56 patients by MRI 1 week and 3 months after curved periacetabular osteotomy performed from August 2017 to December 2019. We classified the condition of the flexors as follows: Grade 0, normal; Grade I, strain/edema; Grade II, partial tear; and grade III, complete tear. RESULTS: At 1 week after surgery, the iliacus muscle was classified as grades I and II in 12.0 and 88.0% of hips; psoas as grades 0, I and II in 22.0, 72.0, and 6.0%; sartorius muscle as grades 0, I and II in 6.0, 62.0, and 32.0%; and rectus femoris muscle as grades 0 and I in 86.0 and 14.0%, respectively. At 3 months, 82.0, 88.0, and 96.0% of psoas, sartorius, and rectus femoris muscles, respectively, had improved to grade 0, whereas the iliacus was grades I and II in 94.0 and 6.0%, respectively. These changes in the iliacus muscle at 3 months were not significantly associated with patient characteristics, radiographic data, or clinical scores. CONCLUSIONS: All the iliacus, 78% of psoas, 94% of sartorius, and 14% of rectus femoris muscles appeared abnormal on MRI 1 week after curved periacetabular osteotomy. However, at 3 months, only 18% of psoas, 12% of sartorius, and 4% of rectus femoris muscles appeared abnormal, whereas all iliacus muscles still appeared abnormal. These abnormalities did not significantly affect clinical scores.

Pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee.

BACKGROUND: In recent years, the involvement of the compensation ability of the subtalar joint in lower extremity alignment has been reported. We previously showed that hindfoot alignment angle (HAA) is an indicator of compensation ability of the subtalar joint. The abnormal compensation ability of the subtalar joint was defined by the mobility of the subtalar joint, and evaluation of the mobility of the subtalar joint may help to further clarify the pathophysiology of abnormal compensation ability of the subtalar joint. This study was performed to evaluate the mobility of the subtalar joint and clarify the pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee. METHODS: Seventy-two knees of 72 patients aged ≥40 years with varus knee were included in this study. Preoperative radiographs were used for measurement of this study parameters. Based on our previous study, we defined HAA of ≥15.9°as abnormal compensation ability of the subtalar joint. The patients were divided into an abnormal group (A-group) and normal group (N-group). All measurement parameters were compared between the groups, and correlations between the HAA and each measurement parameter were analyzed. RESULTS: The weight-bearing hindfoot angle (WBHA) (p < 0.001) and non-weight-bearing hindfoot angle (non-WBHA) (p = 0.003), were significantly greater in the A-group than in the N-group. Conversely, the ratio of change in hindfoot alignment (p = 0.006), were significantly smaller in the A-group than in the N-group. The HAA was positively correlated with WBHA (r = 0.66) and non-WBHA (r = 0.43) and negatively correlated with the ratio of change in hindfoot alignment (r = -0.32). CONCLUSIONS: The pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee is thought to involve a state of increased valgus of hindfoot alignment and an inability to move into normal hindfoot alignment. LEVEL OF EVIDENCE: Level Ⅲ, retrospective study.

A case of total hip arthroplasty for nonunion after femoral trochanteric fracture surgery with complete breakage of only the compression screw of the InterTAN nail.

Intramedullary nails are an effective treatment for common femoral trochanteric fractures. However, one of their complications is implant breakage due to poor reduction and nonunion after surgery. We herein report a case of a 54-year-old man who underwent total hip arthroplasty for nonunion after internal fixation of a femoral trochanteric fracture. The femoral trochanteric fracture was treated by internal fixation using the Trigen InterTAN nail. The patient developed symptoms of hip pain 6 months after internal fixation. Nine months after internal fixation, hip radiographs and computed tomography scans showed breakage of only the compression screw. During total hip arthroplasty, we were unable to remove the lag screw and compression screw before the femoral head dislocation because no gap was present between the two screws. Thus, we removed these screws with the femoral head after dislocation of the femoral head. The removed nail was partially damaged at the lag screw hole. This change was retrospectively observed on the preoperative computed tomography scan. Three months after total hip arthroplasty, the patient was able to walk unaided and the hip pain had resolved. If only the compression screw is completely broken after internal fixation with the Trigen InterTAN nail, both the lag screw and compression screw will be difficult to remove with preservation of the femoral head. We effectively managed such a case by not only revision internal fixation but also total hip arthroplasty.

Clinical Outcomes for Total Hip Arthroplasty with and without Previous Curved Periacetabular Osteotomy.

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.

Changes in patellar baja progress until 3 months after medial open-wedge high tibial osteotomy.

PURPOSE: The purpose of this study was to evaluate sequential patellar height changes as well as the factors leading to these changes after medial open-wedge high tibial osteotomy (MOWHTO). METHODS: The study cohort constituted 37 knees from 36 patients who underwent MOWHTO for varus knee. The Caton-Deschamps index (CDI) for patellar height was measured preoperatively and at 2 weeks and 3, 6, and 12 months postoperatively. The factors related to sequential changes in patellar height were evaluated. RESULTS: Significant differences were observed between preoperative CDI and postoperative CDI at all time points (p < .05). Two-week postoperative CDI and postoperative CDI at 3,6,12-months was also significantly different (p < .05). The only significant factor for the change in patellar height between preoperative CDI and postoperative CDI at 2-weeks and 12-months was the change in the Δ medial proximal tibial angle (ΔMPTA) (postoperative MPTA-preoperative MPTA). We could not identify the factor that affected the change in patellar height change from 2-weeks postoperatively. CONCLUSION: The change in patellar height continued sequentially until at least 3 months postoperatively. ΔMPTA was associated with the change in patellar height at 2 weeks postoperatively compared with preoperatively; however, no factors associated with the change in patellar height from 2 weeks postoperatively to 3, 6, and 12-months postoperatively were identified.

Mechanical Influence of Pubic Nonunion on the Stress Distribution After Curved Periacetabular Osteotomy: Patient-Specific Three-Dimensional Finite Element Analysis.

BACKGROUND: 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. METHODS: 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 (mm2) and contact pressure (MPa) in the hip joint as well as the equivalent stress (MPa) at the ischial ramus were evaluated among the 3 FE models. RESULTS: Patient-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). CONCLUSION: 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.

Bone union status of all osteotomy sites one year after curved periacetabular osteotomy based on computed tomography.

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.

Magnetic Resonance Imaging Assessment of Abductor Muscles Shortly After Curved Periacetabular Osteotomy.

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.

Giant cell tumor of the patella: An uncommon cause of anterior knee pain.

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.

Imaging features of periosteal chondroma manifesting as a subcutaneous mass in the index finger.

Periosteal chondroma is a rare benign hyaline cartilage neoplasm that occurs most commonly in the metaphases of long tubular bones. We present a unique case of periosteal chondroma arising in the proximal phalanx of the left index finger in a 12-year-old boy. Physical examination revealed a slightly protuberant, subcutaneous mass. Plain radiographs and computed tomography scans showed a periosteal lesion producing saucerization of the cortex and subjacent cortical sclerosis, without internal matrix calcification. On magnetic resonance imaging, the lesion exhibited intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Contrast-enhanced fat-suppressed T1-weighted images demonstrated peripheral and septal enhancement. The patient underwent a marginal excision with curettage of the underlying bone cortex. Histological examination confirmed the diagnosis of periosteal chondroma. There has been no evidence of local recurrence eight months after surgery. Periosteal chondroma can protrude into the subcutaneous soft tissue causing a palpable mass. Recognition of the typical radiological features can lead to an accurate diagnosis of this rare condition.