A Primer to Hip Dysplasia

Educational Objectives

The goal of this program is to improve the diagnosis and management of hip dysplasia. After hearing and assimilating this program, the clinician will be better able to:

1. Evaluate the various diagnostic tools used to assess hip dysplasia.

Summary

Diagnosis of hip dysplasia: the anteroposterior (AP) pelvis radiograph and false-profile radiograph provide complementary views of the acetabulum; the false-profile view, or the Luque view, is a specific radiographic technique that offers a near-perfect lateral view of the pelvis (65-70 degrees turned to the side) and allows for a comprehensive assessment of the acetabulum and surrounding pelvic bone; a healthy hip socket should point downward and slightly forward; more orientation to the side may lead to improper coverage of the femoral head (FH); this reduced contact area between the cartilage surfaces may cause increased wear and tear

AP view: the patient is placed in a supine or standing position; a vertical line is drawn from the center of the FH, and another line intersects the lateral edge of the joint; the distance between these lines is the lateral center-edge angle; a normal angle is >25 degrees; a smaller angle indicates a higher risk for hip pain and secondary arthritis because of insufficient coverage of the FH by the acetabulum

Tonnis angle (acetabular index): measures orientation of the hip socket relative to the horizontal plane; normal range is 3 to 13 degrees; a larger angle indicates an upward tilt of the socket; this abnormal orientation can lead to improper positioning of the FH and increased wear and tear on the joint

Concepts of anteversion and retroversion: refer to the anterior or posterior tilt of the hip socket; one method involves tracing the anterior and posterior rims of the acetabulum; in a normal hip, the anterior rim is less prominent than the posterior rim, and they intersect at the superior lateral aspect of the joint; however, in retroversion, the anterior rim extends beyond the posterior rim, creating a crossover sign; another sign of retroversion is the posterior wall sign (the posterior rim reaches the center of the FH)

False-profile view: the anterior center-edge angle is measured by drawing a vertical line from the center of the FH and another line intersecting the most anterior part of the joint surface; a normal angle is >30 degrees; lower measurements indicate reduced anterior coverage

Management: reshaping — suitable for young, growing individuals who have an irregularly shaped socket; reorientation — involves surgically repositioning the hip socket to improve alignment and coverage of the FH; labral repair — addresses tears in the acetabular labrum or injury to cartilage surface tendons and other bursa around the hip; the underlying cause of dysplasia must be addressed to prevent recurrent labral tears; hip replacement — considered a last resort for severe cases of dysplasia, especially in older individuals; Bernese periacetabular osteotomy — involves making 3 cuts in the pelvis, ie, one below the hip, one along the pubic ramus, and one on the inside of the quadrilateral surface; the final cut is an incomplete controlled fracture created to avoid significant soft tissue damage

Readings

Lerch TD, Meier MK, Boschung A, et al. Diagnosis of acetabular retroversion: Three signs positive and increased retroversion index have higher specificity and higher diagnostic accuracy compared to isolated positive cross over sign. Eur J Radiol Open. 2022;9:100407. Published 2022 Feb 25. doi:10.1016/j.ejro.2022.100407; Sherman B, Lalonde FD, Schlechter JA. Measuring the acetabular index: An accurate and reliable alternative method of measurement. AJR Am J Roentgenol. 2021;217(1):172-176. doi:10.2214/AJR.20.23358; Venkatadass K, Durga Prasad V, Al Ahmadi NMM, et al. Pelvic osteotomies in hip dysplasia: Why, when and how?. EFORT Open Rev. 2022;7(2):153-163. Published 2022 Feb 15. doi:10.1530/EOR-21-0066; Wilkin GP, Ibrahim MM, Smit KM, et al. A contemporary definition of hip dysplasia and structural instability: Toward a comprehensive classification for acetabular dysplasia. J Arthroplasty. 2017;32(9S):S20-S27. doi:10.1016/j.arth.2017.02.067.

Disclosures

For this program, the following relevant financial relationships were disclosed and mitigated to ensure that no commercial bias has been inserted into this content: Dr. Learned is a paid consultant at Stryker Corporation and Globus Medical, Inc. Members of the planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Learned was recorded at UCI Orthopaedic Surgery Annual Symposium – A Review for Surgeons and Non-Surgeons, held on June 7, 2024, in Newport Beach, CA, and presented by University of California, Irvine. For more information about upcoming CME activities from this presenter, please visit Uci.cloud-cme.com. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.50 CE contact hours.

Lecture ID:

OR480101

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.