The External Obturator Footprint as a Landmark for Stem Depth in Direct Anterior Total Hip Arthroplasty - Clinical Validation

One of the goals of Total Hip Arthroplasty (THA) is to reconstruct leg length as adequately as possible. In order to achieve this one needs landmarks that are visible both on the templating X ray as well as during surgery. The classical posterior and lateral approaches often rely on the distance from the greater trochanter (GT) to the shoulder of the femoral stem or the distance from the lesser trochanter (LT) to the side of the neck osteotomy. If the surgeon finds out on the digital template that the distance from the GT to the shoulder of the implant should be X mm to achieve equal leg length, than the surgeon can try to reconstruct this during surgery. During the Direct Anterior Approach (DAA) these landmarks usually are not visible or require additional dissection injuring important soft tissue structures along the way. One anatomical structure that appears to be always visible during the DAA is the External Obturator tendon (EO). It was recently confirmed that the level of insertion of the EO onto the proximal femur can also always be determined on pre-operative X rays. It therefore represents one of the few landmarks that is visible both on the templating X ray as well as during DAA THA. Indeed, many hip surgeons, including ourselves, believe that if the shoulder of the femoral stem is near the insertion of the EO leg length cannot be far off. However, there is no clinical data to support this. The investigators would therefore like to the correlate the distance observed intra-operatively to the actual established distance on the post-operative X ray.

Study Overview

• Status: Active, not recruiting
• Conditions: Coxarthrosis
• Intervention / Treatment: Procedure: Total Hip arthroplasty via a Direct Anterior Approach

• Study Type: Observational
• Enrollment (Actual): 50

Contacts and Locations

Study Locations

• Belgium
  • Leuven, Belgium, 3000
    • University Hospitals Leuven - Gasthuisberg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

All patient who underwent THA via DAA by a single surgeon who routinely documents the distance from the shoulder of the stem to the upper border of the EO tendon

Description

Inclusion Criteria:

• All patient who underwent THA via DAA by a single surgeon who routinely documents the distance from the shoulder of the stem to the upper border of the EO tendon

Exclusion Criteria:

• Distance not noted
• No radiographs available

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Retrospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients who underwent DAA THA; Patients who underwent DAA THA by a single surgeon who routinely documents the distance from the should of the stem to the upper end of the EO footprint	Procedure: Total Hip arthroplasty via a Direct Anterior Approach; Total Hip arthroplasty via a Direct Anterior Approach

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Correlation between the distance measured intra-operatively and presumed distance on the pelvic radiographs	2 days

Secondary Outcome Measures

Outcome Measure	Time Frame
Visibility of the EO tendon intra-operatively	2 days
Inter and intra-rater reliability	2 days

Collaborators and Investigators

• Sponsor: Universitaire Ziekenhuizen KU Leuven

Publications and helpful links

General Publications

• Rudiger HA, Fritz B, Impellizzeri FM, Leunig M, Pfirrmann CW, Sutter R. The external obturator footprint as a landmark in total hip arthroplasty through a direct anterior approach: a CT-based analysis. Hip Int. 2019 Jan;29(1):96-101. doi: 10.1177/1120700018761320. Epub 2018 May 21.
• Vles G, Meynen A, De Mulder J, Ghijselings S. The External Obturator Footprint Is a Usable, Accurate, and Reliable Landmark for Stem Depth in Direct Anterior THA. Clin Orthop Relat Res. 2021 Aug 1;479(8):1842-1848. doi: 10.1097/CORR.0000000000001799.

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2021
• Primary Completion (Anticipated): January 1, 2022
• Study Completion (Anticipated): January 1, 2022

Study Registration Dates

• First Submitted: November 3, 2020
• First Submitted That Met QC Criteria: November 3, 2020
• First Posted (Actual): November 10, 2020

Study Record Updates

• Last Update Posted (Actual): March 3, 2021
• Last Update Submitted That Met QC Criteria: March 1, 2021
• Last Verified: March 1, 2021

More Information

Terms related to this study

• Keywords: direct anterior approach; leg length; templating; Total hip Arthroplasty; external obturator footprint
• Additional Relevant MeSH Terms: Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Arthritis; Osteoarthritis; Osteoarthritis, Hip
• Other Study ID Numbers: s63944

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No