Measurement Of Acetabular Prosthesis Anteversion Angle In Total Hip Arthroplasty With A Word Lamp Combined With A Camera Protractor

Objective: To explore the clinical reference value and accuracy in total hip arthroplasty(THA)of using a word line laser positioning lamp combined with a mobile phone camera protractor to measure the anteversion angle of acetabular component.Methods: Clinical datas were selected from our hospital's four ward of orthopedics department in March 2015 to September 2016,and all patients were treated with total hip arthroplasty for the first time.The patient's surgery was completed by the same physician in the THA.A total of 47 patients(49 hips)were enrolled in this study who included Developmental Dysplasia of the Hip(type ?)5 cases(6 hips),necrosis of the femoral head 9 cases(10 hips),fracture of the femoral neck 21 cases,hip arthritis 12 cases.To use of a word line laser positioning lamp combined with mobile phone camera protractor to measure the acetabular prosthesis anteversion angle during operation,and the anteversion angle of the acetabular component were measured using the postoperative fifth day of the patient's pelvic double hip posteroanterior radiograph in Picture Archiving and Communication Systems(PACS).The two groups of datas were statistically analyzed.We used the intraclass correlation coefficient(ICC)to estimate the credibility of the measurement method.By using two independent samples t-test to compare the intraoperative and postoperative measurement of the anteversion values whether are different or not.By limitation of the patient's anteversion angle of acetabular cup which was measured of using the PACS system.if the angle is greater than its by the camera angle protractor measurement in operation.We were defined as positive,whereas as negative to calculate the size of the error range of the measurement method in this subject.Results: The ICC was 0.83 in the anteversionangle of acetabular component by the Mobile phone camera protractor and PACS measurement methods.The acetabular component anteversion angle was(18.31±1.98)° by Mobile phone camera protractor measurement.The acetabular component anteversion angle was(17.96±5.12)° by our hospital's PACS measurement.There was no statistically significant difference between the two methods in this subject(P>0.05).47 patients(49 hips)with acetabular prosthesis anteversion angle measured by PACS whose remained within safe zone in 44 hips,and 5 hips were beyond safe range of 1 to 4°.The results of intraoperative measurements compared with the results measured by our hospital PACS were-16 to +8 °,which indicated that the acetabular component anteversion angle by Mobile phone camera protractor measurement was larger than that by the PACS measurementConclusion: By using of a word line laser positioning lamp combined with mobile phone camera protractor,in the initial total hip arthroplasty positioning of the acetabular prosthesis angle has a good reference value.