Predictability of the progress of secondary osteoarthritis after developmental dislocation of the hip, utilizing inferior edge (of the teardrop)--center (of the femoral head) distance

"Koehlers teardrop is not a reliable landmark for assessing the centre of rotation after Total hip arthroplasty" - a retrospective radiological study

PURPOSE

Various anatomical landmarks have become established in radiography for the assessment of cup positioning after total hip arthroplasty (THA). The most important one is Koehler's teardrop figure (KTF). However, there is a lack of data on the validity of this landmark, which is widely used clinically for assessing the centre of rotation of the hip.

METHOD

A retrospective measurement of the lateral and cranial distance of the KTF to the centre of hip rotation was performed on the basis of 250 X-ray images of patients who had undergone THA. In addition, the dependence of these distances on pelvic tilt was determined in 16 patients by means of virtual X-ray projections based on pelvic CTs.

RESULTS

It was shown that the distance of the KTF from the centre of hip rotation in the horizontal plane is gender-dependent (men: 42.8 ± 6.0 mm vs. women: 37.4 ± 4.7 mm; p < 0.001) and age-dependent (Pearson correlation  - 0.114; p < 0.05). Furthermore, the vertical and horizontal distances are subject to variation depending on height (Pearson correlation 0.14; p < 0.05 and 0.40; p < 0.001, respectively) and weight (Pearson correlation 0.158; p < 0.05). The distance between the KTF and the centre of hip rotation varies slightly depending on pelvic tilt.

CONCLUSION

The KTF is not a sufficiently valid landmark for assessing the centre of rotation after THA. It is influenced by many different disturbance variables. However, it is largely robust against changes in pelvic tilt, so that it can be used as a reference point when comparing different intraindividual radiographs to assess the change in the centre of rotation due to implantation or to detect cup migration.

Comparison of four parameters to assess acetabular dysplasia and acetabular dysplasia rates in primary hip osteoarthritis patients: A study in Turkish population

INTRODUCTION

Hip osteoarthritis is an important orthopedic problem frequently observed in the elderly. Acetabular dysplasia (AD) is one of the pathologies that cause coxarthrosis. Nearly 20-45% of primary or idiopathic hip osteoarthritis is linked to AD. In our country, there are few studies on this topic. We measured the center-edge (CE) angle, Sharp's angle, acetabular depth, and femoral head coverage ratio on pelvis anteroposterior radiographs of patients with primary coxarthrosis and calculated the dysplasia rates.

PATIENTS AND METHOD

Age at surgery and sex of the patients; and CE angle, Sharp's angle, acetabular depth, and femoral head coverage ratio for both operated and opposite hips were evaluated in 223 total hip prosthesis-performed patients with coxarthrosis. Also the distribution of mean age at surgery, sex of patients, dysplasia rates of operated hips, and bilateral dysplasia rates were calculated.

RESULTS

The right to left ratio of operated hips was 104/119. Female to male ratio was 163/60 (2.7/1), for those with CE angle below 20° it was 123/30 (4.1/1), and it was 40/30 (1.3/1) with CE angle above 20°. Mean age of patients at surgery was 56.9 (±11.4) years. CE angle less than 20° was found in 68.6% of patients, acetabulum depth less than 9 mm was found in 75.3%, Sharp's angle was more than 45° in 65.9%, and femoral head coverage ratio was less than 70% in 70.3% of patients.

CONCLUSIONS

We identified a high rate of AD in primary coxarthrosis patients undergoing total hip arthroplasty in the study population.

Seasonal trends in the incidence of hip osteoarthritis in Japanese patients

Purpose:

There is an association between winter birth and developmental dysplasia of the hip, formerly termed congenital dislocation of the hip. The purpose of this study was to clarify the relationship between the month and season of birth and hip osteoarthritis in Japanese patients who had undergone total hip arthroplasty or transpositional osteotomy of the acetabulum.

Methods:

One thousand eight hundred and 52 female patients that presented for the surgical treatment of hip osteoarthritis between 1999 and 2005 were included in this study. Female out-patients who were seen at the initial visit during same period were used as controls to correct the bias of the month of birth.

Results:

There was a significant deviation of the observed number of births from the expected values calculated on a monthly basis (p<0.001). A comparison by seasons (periods of 3 months) revealed more births than expected in winter (p<0.001). The risk of hip osteoarthritis was significantly associated with the month of birth. Namely, it was highest for births in January (p<0.001).

Conclusions:

These data clearly revealed that the prevalence of hip osteoarthritis was significantly higher in those patients born in winter. The seasonal trend in hip osteoarthritis might be due to the winter prevalence of congenital dislocation of the hip in childhood.

Anticipatory Postural Adjustments During Lateral Step Motion in Patients With Hip Osteoarthritis

Patients with hip osteoarthritis (OA) have difficulty with mediolateral postural control. Since the symptom of hip OA includes joint pain, which mostly occurs upon initial movement, patients with hip OA might have disabling problems with movement initiation. This study aimed to identify the movement strategy during the anticipatory postural adjustments in the lateral step motion in patients with hip OA. We studied 18 female subjects with unilateral hip OA and 10 healthy subjects, and measured temporal, kinetic, and kinematic variables. Patients with hip OA required a longer duration of anticipation phase than the control subjects, the total duration of lateral stepping was not different between the groups. Displacement of the center of mass to the supporting (affected) side during the anticipation phase was not different between the two groups. These findings suggest that, in patients with hip OA, the center of mass slowly moved to the affected side. Furthermore, patients with hip OA showed greater shift of the trunk to the supporting side than did the control subjects. These movement characteristics might contribute to the achievement of both protection of the affected hip joint and quickness in the subsequent lateral step in patients with hip OA.

Acetabular and proximal femoral alignment in patients with osteoarthritis of the dysplastic hip and its influence on the progression of disease

In order to evaluate the relationship between acetabular and proximal femoral alignment in the initiation and evolution of osteoarthritis of the dysplastic hip, the acetabular and femoral angles were calculated geometrically from radiographs of 62 patients with pre-arthrosis and early osteoarthritis. The sum of the lateral opening angle of the acetabulum and the neck-shaft angle was defined as the lateral instability index (LII), and the sum of the anterior opening angle of the acetabulum and the anteversion angle of the femoral neck as the anterior instability index (AII). These two indices were compared in dysplastic and unaffected hips. A total of 22 unilateral hips with pre-arthrosis were followed for at least 15 years to determine whether the two indices were associated with the progression of osteoarthritis. The LII of the affected hips (197.4 (sd 6.0)) was significantly greater than that of the unaffected hips (1830 (sd 6.9)). A follow-up study of 22 hips with pre-arthrosis showed that only the LII was associated with progression of the disease, and an LII of 196 was the threshold value for this progression.