Backgrounds: This study aimed to investigate the characteristic deformities of the hip in multiple hereditary exostoses patients (MHE) and its association with the hip impingement syndrome.Materials and methods: Between 2001 and 2019, total 51 patients (102 hips) were evaluated in this study. Patients with MHE were classified to femoro-acetabular impingement (FAI) symptom group, ischio-femoral impingement (IFI) symptom group and non-impingement symptom group by comparing the symptoms, clinical signs and imaging studies. To assess the morphometry of the hip in patients with MHE, the femoral neck-shaft angle, Sharp’s acetabular angle and center-edge (CE) angle were evaluated. Alpha angle was further evaluated to investigate the FAI using radiographs, and the minimum ischio-femoral distance was further measured to investigate the IFI using computed-tomographic (CT) study.Results: On hip impingement symptom analysis, FAI symptom and IFI symptom were confirmed in 14 hip joints and 18 hip joints, respectively. Unlike general population, the number of the hip with IFI-symptom was higher than those with FAI symptom in this study. In morphometric evaluation of MHE hips, coxa valga was most prominent deformity with occasional tendency of mild acetabular dysplasia. In a comparison of morphometric study between the impingement symptom group and non-symptom group, the FAI symptom showed significant differences of morphometric measure values than those of the non-symptom group (FAI symptom group vs. Non-FAI symptom group; Femoral neck-shaft angle (153.9 vs 142.6), Sharp’s angle (45.0 vs 41.5), CE angle (21.1 vs 28.8) and alpha angle (76.7 vs 57.9)). Similarly, the IFI symptom group also showed significant differences of morphometric measure values than those of the non-symptom group (IFI-symptom vs. Non-IFI symptom; Femoral neck-shaft angle (150.9 vs 142.7), Sharp’s angle (44.7 vs 41.4), CE angle (21.1 vs 29.3) and alpha angle (73.3 vs 56.8)). In addition, the minimum ischio-femoral distance measured using CT was significantly decreased in the IFI symptom group (IFI symptom group: 6.6, Non-IFI symptom group: 16.4).Conclusion: The results suggest that the characteristic deformities represented by coxa valga in the MHE hip act as an offset for FAI symptoms, on the contrary, act as a trigger for IFI symptoms.Level of evidence: Level III.

Modular endoprostheses are frequently used to reconstruct skeletal and knee defects from bone tumor resection and preserve joint function in patients with bone tumors around the knee. Depending on the tumor location, the muscles and extent of the tumor can vary, which can affect gait function. This study aimed to analyze kinetic and kinematic characteristics according to tumor location in patients with endoprosthetic knee replacements after bone tumor resection. Gait analyses were performed in 16 patients who underwent knee endoprosthesis due to tumors around the knee. We divided the patients into distal femur (n = 7) and proximal tibia (n = 9) groups and conducted between-group comparisons and comparisons with healthy participants. Compared with the control group, the distal femur group showed a tendency for knee extension, and the proximal tibia group showed increased maximal dorsiflexion during stance. The proximal tibia group maintained a flexed hip during the entire gait cycle, compared with the distal femur group. In summary, our results suggest a difference in gait between the distal femur and proximal tibia groups. Patients who have undergone knee prosthesis after knee tumor resection may require different rehabilitation strategies according to the tumor location.

A giant cell tumor (GCT) of the bone is characteristically found in skeletally mature patients. The tumor is rare in pediatric patients, and incidence reported in literature varies from 1.8% to 10.6%. We performed a retrospective study addressing symptoms, treatment, and outcome in pediatric patients who were diagnosed with GCT between March 1997 and January 2015 at our hospital. Fourteen (11.1%) of 126 surgically treated patients with histologically proven GCT were <19 years of age. We confirmed skeletal maturity using magnetic resonance imaging (MRI). Fourteen patients from 8 to 19 years old were identified. Sixteen lesions (76.2%) were found in long bones and 5 lesions (23.8%) in short bones. The most common site was around the knee in 8 patients (38%). GCTs mostly occur at the epi-metaphysis in 11 patients (52.3%). Regardless of the openness of epiphyseal plate, we observed GCT of bone in the epiphysis. Further study will be needed to prove the association between the presence of epiphyseal plate and location of tumor. Three patients (21.4%) had multicentric lesions, and four patients (28.5%) had local recurrence. Multicentric giant cell tumor and local recurrence occur more often in pediatric patients. The characteristics of GCT in pediatric patients do not differ from what is reported for GCT in adults.

Background: Slipped capital femoral epiphysis (SCFE) is a hip disorder that occurs in adolescence before epiphyseal plate closure, causing anatomical changes in the femoral head. Obesity is known to be the single most important risk factor for idiopathic slipped capital femoral epiphysis (SCFE), which is highly related to mechanical factors. Meanwhile, as increased slip angle increases major complications in patients with SCFE, slip severity is an important factor to evaluate prognosis. In obese patients with SCFE, higher shear stress is loaded on the joint, which increases the likelihood of slip. The study aim was to assess the patients with SCFE treated with in situ screw fixation according to the degree of the obesity and to find any factors affecting the severity of slip. Methods: Overall, 68 patients (74 hips) with SCFE who were treated with in situ fixation screw fixation were included (mean age 11.38, range: 6–16) years. There were 53 males (77.9%) and 15 females (22.1%). Patients were categorized underweight, normal weight, overweight, and obese depending on BMI percentile for age. We determined slip severity of patients using the Southwick angle. The slip severity was defined as mild if the angle difference was less than 30 degrees, moderate if the angle difference was between 30 and 50 degrees, and severe if the angle difference was greater than 50 degrees. To examine the effects of several variables on slip severity, we used a univariable and multivariate regression analysis. The following data were analyzed: age at surgery, sex, BMI, symptom duration before diagnosis (acute, chronic, and acute on chronic), stability, and ability to ambulate at the time of the hospital visit. Results: The mean BMI was 25.18 (range: 14.7–33.4) kg/m². There were more patients with overweight and obese than those with normal weight in SCFE (81.1% vs. 18.9%). We did not find significant differences between overall slip severity and degree of obesity or in any subgroup analysis. Conclusions: We did not find a relationship between slip severity and degree of obesity. A prospective study related to the mechanical factors affecting the slip severity according to the degree of obesity is needed.

The purpose of this study was to evaluate the outcomes of patients with Legg–Calvé–Perthes disease (LCPD) with disease onset before 6 years of age who were treated with conservative methods and to identify prognostic factors. Moreover, we evaluated the duration of the Waldenström stage and its correlation with the disease outcome. Disease severity was assessed using the lateral pillar classification, and the final outcome was evaluated using the Stulberg classification. We divided patients with LCPD into two groups according to the age at onset: group 1 (<4 years) and group 2 (4–6 years). The final outcomes of the two groups were compared. We also assessed the duration of each Waldenström stage. LCPD was noted in 49 hips of 49 patients. The lateral pillar class was A in one patient, B in 29 patients, and B/C or C in 19 patients. The Stulberg class was I or II (good) in 30 patients, III (fair) in 13 patients, and IV or V (poor) in six patients. The lateral pillar class significantly correlated with the final outcome. Groups 1 and 2 comprised 25 and 24 patients, respectively. The prevalence of good outcomes did not significantly differ between the groups (p = 0.162). The duration of the initial stage was 4.1 months in the good outcome group and 6.2 months in the fair or poor outcome group. The duration of the fragmentation stage of the femoral head was 5.9 months in the good outcome group and 11.9 months in the fair or poor outcome group. The durations of initial and fragmentation stages significantly differed between good outcome group and fair or poor outcome group (p = 0.009 and p < 0.001, respectively). The prognosis of patients with disease onset before the age of 6 years was favorable. The disease severity and duration of each Waldenström stage can be predictors of the outcome. Patients with prolonged initial and fragmentation stages showed worse outcomes and often required more active treatment to shorten the durations of the initial and fragmentation stages.