Reliability Of A Simple Fluoroscopic Image To Assess Leg Length Discrepancy During Direct Anterior Approach Total Hip Arthroplasty

Abstract

Background Direct Anterior Approach (Daa) Total Hip Arthroplasty (Tha) In A Supine Position Provides A Unique Opportunity To Assess Leg Length Discrepancy (Lld) Intra-Operatively With Fluoroscopy. Reported Fluoroscopic Techniques Are Useful But Are Generally Complicated Or Costly. Despite The Use Of Multiple Techniques For Leg Length Assessment, Lld Continues To Be A Major Post-Operative Source Of Patient Dissatisfaction Further Emphasizing The Importance Of Near-Anatomic Restoration. The Utility Of An Alternative Direct Measurement Of Lld On An Intra-Operative Fluoroscopic Pelvic Image During Daa Tha Has Not Been Reported. Aim To Determine The Reliability Of A Novel Simple Intra-Operative Measurement Of Lld Using A Parallel Line Technique On A Single Fluoroscopic Digital Image Of The Pelvis. Methods One Hundred And Seventy-One Patients Who Underwent Daa Tha Were Included For Analysis. Intra-Operative Fluoroscopic And Post-Operative Anterior-Posterior Radiographs Were Imported To Traumacad And Calibrated For Lld Measurement. Lld Was Measured On Each Image Using The Right-Left Hip Differences In Lesser Trochanter To Pelvic Reference Line Distances. Pelvic Reference Points Included The Teardrops And Ischia. Fluoroscopic Lld Was Compared To The Gold-Standard Measurement Of Lld Measured On A Post-Operative Radiograph. Results Mean Absolute Difference In Teardrop Referenced Lld Between Fluoroscopic And Post-Operative Radiographs Was 2.17 Mm And Based On The Ischia Mean Absolute Difference Was 2.63 Mm. Linear Regression Of Fluoroscopic And Post-Operativeradiograph Lld Based On Teardrop And Ischia Lld Found R 2 Values Of 0.57 And 0.84, Respectively. Mean Absolute Difference Between Fluoroscopic And Post-Operative X-Ray Lld Was Within 5 Mm In 95% Of Cases Regardless Of Pelvic Reference. Conclusion This Study Demonstrates That A Single Fluoroscopic View Obtained During Daa Tha For Leg Length Assessment Is Clinically Useful