Improving Surgeons’ Intraoperative Estimation of Stem Anteversion for Hip Arthroplasty by Using Digital Protractor: a Preliminary Report

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พัฒนพงศ์ ปาละวงศ์
อนุวัตร พงษ์คุณากร
ศวิษฐ์ ฉัตรไมตรี


Background: Conventional technique for estimating femoral stem anteversion intraoperatively during hip arthroplasty by surgeon visualization is proven to be inaccurate.
Objective: To determine the accuracy of a new technique of using digital protractor for improving surgeons’ intraoperative estimation of stem anteversion.
Material and method: A prospective observational study was conducted on 69 patients with femoral neck fracture and OA hip who underwent hemi-arthroplasty and total hip arthroplasty in Lampang Hospital during January 2016 and March 2017. The intra-operative femoral stem anteversion was measured by placing a digital protractor to the femoral broach during the assistant hold the leg in the truly vertical position and compared with the anteversion angle
measured in CT scan postopertively. Percentage of the stems having postoperative anteversion angle different from intra-operatively measured angle within 5o was calculated and analyzed for correlation with clinical data by using regression analysis.
Results: Most of the patients were female (62.3%) with the mean age of 63.6 ± 13.8 years (rage, 21-91). Most of diagnoses were femoral neck fracture (59.4%) and osteonecrosis of femoral head (20.3%).Total hip arthroplasty was performed in 55.1% and posterolateral approach was used in 75.4 % of the patients. In posterolateral approach group, the difference between intra-operative and postoperative angle was -0.1o ± 4.2o (p=0.895) and 80.8 % of stems had <5o
of difference. In direct lateral approach group, the average difference was -2.7o ± 10.3o (p=0.313) and 47.1% of stems had <5o of difference.
Conclusion: Using digital protractor for intraoperative estimation of stem anteversion had high
accuracy within 5o of errors for posterolateral approach.


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ปาละวงศ์ พ., พงษ์คุณากร อ., & ฉัตรไมตรี ศ. (2019). Improving Surgeons’ Intraoperative Estimation of Stem Anteversion for Hip Arthroplasty by Using Digital Protractor: a Preliminary Report. Lampang Medical Journal, 38(1), 29–37. Retrieved from
Original Article


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