Validity, Reliability and Reproducibility of Plain Radiographic Measurements After Total Hip Arthroplasty

Sundsvall Hospital90 enrolled

Overview

In total hip arthroplasty (THA), radiographic preoperative planning and postoperative evaluation of acetabular component, femoral offset (FO) and leg length discrepancy (LLD) require good validity, interobserver reliability and intraobserver reproducibility. Questions/purposes: (1) Evaluate the validity of the Sundsvall method of FO measurement by comparing it to a standard FO measurement method. (2) Evaluate the interobserver reliability and intraobserver reproducibility of measurement of FO, LLD, acetabular cup inclination and anteversion. 90 patients with primary unilateral osteoarthritis (OA) were included in this prospective study. On postoperative radiographs FO by the Sundsvall method, FO by a standard method, LLD, acetabular cup inclination and anteversion were measured. The interobserver reliability and intraobserver reproducibility were made by three independent observers. The validity and degree of prediction of Sundsvall method are measured by comparing its results with the standard method.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Osteoarthritis of the Hip

Eligibility

Sex: ALL

Medical Language ↔ Plain English

Inclusion Criteria: * unilateral total hip replacement with either a cemented Lubinus SP II system (Link, Germany) or an uncemented CLS stem and Triology cup (Zimmer, U.S.A). Exclusion Criteria: * Patient with secondary (OA), previous spinal, pelvic, or lower limb injuries or fractures were excluded.

Locations (1)

Outcomes

Primary Outcomes

Leg Length Discrepancy

LLD on radiographs was defined as the difference in perpendicular distance in millimetres between a line passing through the lower edge of the teardrop points to the corresponding tip of the lesser trochanter. The interobserver reliability was assessed from the measurements made by three independent observers.

Time frame: 1 week

Femoral offset (Sundsvall method)

Measurement of FO using the Sundsvall method was carried out on the AP view of the pelvis as the horizontal distance (parallel to Hilgenreiners line) between the femoral axis (a line drawn through the center of the femoral shaft) and the mid line of the pelvis, at the height of the lateral tip of the greater trochanter. The measurement was performed bilaterally to compare the femoral offset on the operated side to the non-operated hip. The interobserver reliability was assessed from the measurements made by three independent observers.

Time frame: 1 week

Femoral offset (standard method)

Measurement of FO with the standard method was carried out on AP view as the addition of the distance between the longitudinal axis of the femur to center of femoral head and the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis. The measurement was repeated bilaterally to compare the FO of the operated side to non-operated hip. The interobserver reliability was assessed from the measurements made by three independent observers.

Time frame: 1 week

Cup inclination

Cup inclination was measured on AP view as angle in degrees, between a line drawn along the angle of rim of the cup and trans-ischial line (a line drawn between the most inferior point of the ischial tuberosities). The interobserver reliability was assessed from the measurements made by three independent observers.

Time frame: 1 week

Acetabular cup anteversion

Acetabular cup anteversion was measured on lateral radiograph as the angle formed by the intersection of a line drawn across the face of acetabulum and a line perpendicular to the horizontal plane, according to the Woo and Morry method. The interobserver reliability was assessed from the measurements made by three independent observers.

Time frame: 1 week