COVID-19 with Suspected Secondary Pyogenic Arthritis of the Hip: A Case Report and Literature Review.

Introduction: COVID-19 may be associated with orthopedic symptoms, including myalgia and joint pain. There are reports of reactive arthritis and acute arthritis diagnosed after COVID-19; however, COVID-19-associated pyogenic arthritis has not been reported. Case Report: We treated a young woman with secondary pyogenic hip arthritis that started after COVID-19. The patient was a 23-year-old woman who developed acute pain in the right hip 9 days after being diagnosed with COVID-19. Blood cultures revealed methicillin-sensitive Staphylococcus aureus and contrast-enhanced computed tomography revealed joint effusion in the right hip. Although the joint fluid culture results were negative, we suspected pyogenic arthritis of the hip joint and performed curettage and continuous irrigation of the right hip joint. Intraoperative histopathological examination of the synovial membrane revealed numerous neutrophils with segmental nuclei, consistent with a diagnosis of pyogenic arthritis. Conclusion: To the best of our knowledge, this is the first report of probable secondary pyogenic hip arthritis in a patient with COVID-19.

Two Healthy Elderly Females with Contemporaneous Subchondral Insufficiency Fractures of Bilateral Femoral Heads: A Case Report.

Introduction: Unilateral subchondral insufficiency fractures (SIF) of the femoral head have been reported in many cases; however, bilateral cases occurring simultaneously are very rare. Case Report: We report two cases of relatively active elderly females (aged 73 and 67 years), in which bilateral hip pain appeared simultaneously without any specific triggers. There were no notable lifestyle or medication histories. Imaging and histopathology of the bone excised surgically supported the diagnosis. In Case 1, there was a decrease in bone mineral density and poor congruency between the femoral head and acetabulum. In Case 2, the posterior tilt of the pelvis with aging decreased coverage of the femoral head, and the poor congruency between the femoral head and acetabulum was thought to have contributed to uneven distribution and increased stress in the loading zone. Conclusion: We encountered two unusual cases with contemporaneous bilateral SIF in the elderly. In recent years, the number of highly active elderly people has increased with the increase in healthy life expectancy. The combined effect of factors such as bone fragility, posterior pelvic tilt, and high activity level likely caused bilateral SIFs, and we should be careful as we expect to see an increase in such cases in the future.

Femoral Bowing Increases Early Postoperative Stress around the Femoral Stem in Humans: A Finite Element Analysis.

Background: This study aimed to clarify the characteristics of stress distribution caused by the placement of tapered wedge stems in bowed femurs compared with that in normal femurs and the effect of varus stem placement. Methods: Models with normal and enhanced bowing were created from the right-side computed tomography data of a 17-year-old woman with the least bowing among 40 participants who underwent anterior cruciate ligament reconstruction or operative treatment for trauma in our hospital between January 2017 and May 2018. Finite element analysis was performed, assuming the tapered wedge stem was placed in the neutral and varus positions. Results: Varus stem placement on a femur with normal bowing showed a deviation and increase of von Mises stresses in the medial femur. Stem placement on a bowed femur, even when placed in the neutral position, increased stress across the periprosthetic bone. When the stem was placed in the varus position, von Mises stress across the periprosthetic bone increased. Zone 7, with strong bowing, demonstrated 3.6-fold increased stress compared with normal femurs. The maximum tensile principal stress was greatest in zone 6 and increased in zones 3 and 4. Conclusions: Surgeons should assess femoral bowing preoperatively and pay particular attention to intraoperative stem alignment for femurs with high bowing.

Relationship between perceived and structural leg length discrepancies of patients with hip osteoarthritis dysplasia.

BACKGROUND: Only few studies have been conducted on leg length discrepancy (LLD) in patients with hip osteoarthritis (OA). This study aimed to examine the relationship between perceived LLD (pLLD) and structural LLD (sLLD) in patients with advanced OA and to determine the factors influencing both LLDs. This retrospective study aimed to answer the following questions: (1) are older adults less likely to perceive LLD than younger adults? (2) is there a relationship between pLLD and sLLD? and (3) is pLLD associated with patient satisfaction? HYPOTHESIS: We hypothesized that older adults are less likely to perceive LLD than younger adults. PATIENTS AND METHODS: We recruited 125 patients (102 women and 23 men) with hip OA associated with developmental dysplasia of the hip defined as grade 3 or higher according to the Tönnis classification and excluding contralateral grade 2 or higher. The mean age of the patients was 65.2±11.2 (36-85) years. Before surgery, 2-mm and 5-mm thick plates were placed on the floor on the plantar surface of the short leg to measure pLLD. Preoperative computed tomography (CT) was performed and sLLDs were measured using the 3D planning software ZedHip. The following associated factors were evaluated: age, height, weight, body mass index (BMI), adduction and abduction range of motion (ROM) of the affected hip joint, Crowe classification, standing pelvic inclination in the coronal plane, Cobb angle and Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). RESULTS: The absolute difference between pLLD and sLLD was modestly positively correlated with age (R=0.206; p<0.05) indicating older patients were less prone to perceive LLD. A strong positive correlation was found between pLLD (4.8±7.3mm; range: -37 to 28mm) and sLLD (6.4±7.0mm; range: -29.9 to 23.7mm) (R=0.714, p<0.05). The greater the pLLD, the smaller the hip abduction ROM (24.8±11.6°; range: 0 to 45°) tended to be, while the greater the sLLD, the smaller the hip abduction and adduction ROM (10.3±5.7°; range: 0 to 25°) tended to be (R= -0.259 and R= -0.297, respectively; p<0.05) The clinical significance of this finding is that pLLD may be improved if hip ROM training is performed before surgery. pLLD was significantly smaller in the group without pelvic inclination (8.0±14.1mm; range: -37 to 22mm) than in the group with pelvic inclination to the affected side (6.9±7.5mm; range: -12 to 28mm) and in the group with no inclination to the affected side (7.3±7.6mm; range: -8 to 25mm) (p<0.05) The clinical significance of this finding is that improving pelvic inclination with hip ROM training or muscle stretching may also reduce pLLD. No significant differences were noted between pLLD and JHEQ total scores or subgroups. DISCUSSION: Older patients had less pLLD. Preoperative pLLD was strongly correlated with sLLD but not with patient satisfaction. These results may be useful for conservative treatment of OA, preoperative planning and intraoperative leg length correction. LEVEL OF EVIDENCE: IV; case control study.

Influence of femoral bowing on stress distribution of the proximal femur: a three-dimensional finite element analysis.

BACKGROUND: Whether femoral bowing or its direction has a mechanical effect on the proximal femur is unclear. This study aimed to define the changes in stress distribution in the proximal femur associated with femoral bowing using finite element analysis. METHODS: We created four femoral models: original, entire lateral bowing, entire anterior bowing, and the middle of both (50% anterolateral bowing) from computed tomography data of women with standard bowing. Each model's stress distribution was compared by two-layering the stress distribution under loading conditions during walking. We also evaluated displacement vectors. RESULTS: In all directions of femoral bowing, the stress increased in the femoral neck and the femoral trochanter in the 50% anterolateral bowing. The direction of deformation of the vector for the femoral head increased anteroinferiorly in the 50% anterolateral bowing. CONCLUSIONS: This study showed that the stress distribution at the proximal femur shifted laterally. The high-stress area increased at the femoral neck or trochanter due to increasing femoral bowing. Femoral bowing also increases the anteroinferior vector in the femoral head. This study provides valuable insights into the mechanism of proximal femoral fractures in older adults.