Evolving Techniques: Patient specific S pecific Targets for Cup Position in Total Hip Arthroplasty Stefan Kreuzer, MD Houston, Texas
Disclosures/ Affiliations: Device companies Board Member/ Advisory Board • Corin: Consult ing/ speaking, Research support , Royalt ies • IS TA • S mit h and Nephew: Consult ing/ speaking, Research support , • ICJR Royalt ies (in t he past ) • MBJ-RF • S t ryker: Royalt ies • S urgical Care Affiliates: Medical Advisory Board • Zimmer/ Biomet: Consult ing, Royalt ies • Employers Direct : Medical Advisory Board • Medt ronic: Consult ing/ speaking Investments/ ownership : • Depuy: Research support t hrough MBJ-RF • IOT • Pacira: Consult ing/ S peaking • K and S solut ions • Brain Lab: Consult ing/ speaking • Alpoza • Int elli-Joint S urgical: Consult ing/ speaking • Ort hosensor • Think S urgical: Consult ing, Research • Argent um Medical (silverlone) • Knee 360: Consult ing (none-compensates) • Inov8 S urgical • S hukla: Consult ing • Invo8 Healt hcare • S wift Pat h: Consult ing/ speaking • First S t reet S urgical Hospit al • Pulse: Consult ing/ speaking, Royalt ies • Texo-Venture • Y our Pract ice on line: Consult ing (none compensat ed) • Employers Direct
“The dogmas of the quiet past are inadequate to the stormy present… As our case is new, so we must think anew, and act anew.”
The first ‘safe zone’ Lewinnek 1 defined safe zone as Normal 30-50° inclination and 5-25° Dislocated anteversion anterior Angle (degrees) posterior 36 yr old analysis (JBJS 1978) unknown 9 dislocations (3 in the safe zone) 300 THRs - only 113 X-rays analysed from the 291 non- dislocated patients Relative to the APP Angle (degrees) 1. Lewinnek, et el, 1978, JBJS
Facts on Dislocation: HSS • The frequency of dislocation was 2.1% (147 of 7040 patients).
Is a safe zone really safe? M. Abdel 2 - AAHKS Nov 2014 12,000 Hips implanted between Angle (degrees) 2003 and 2012 at the Mayo clinic Minimum 2 yr follow up 1.9% (224 hips) dislocated 58% of dislocations were inside the Lewinnek safe zone. Angle (degrees) 1. Lewinnek, et el, 1978, JBJS 2. Abdel, AAHKS, 2014
Introduction The pelvis rotates in the sagittal plane, consequently in patients with THR, the functional cup orientation changes Posterior Tilt Anterior Tilt
Consequences Posterior Rotation Anterior Rotation Bad in hip extension Bad in hip flexion
1517 patients
Variation of functional pelvic tilt
Variation of functional pelvic tilt
Variation of functional pelvic tilt
S ymptomatic THRs analysed in supine 40% in “ safe zone”
S ymptomatic THRs analysed functionally 13% in “ safe zone”
Functional Boundaries
Take Home’s… • 40 - 60% of dislocating/ squeaking hips are within published safe-zones • However, when analysed functionally this number falls to only 13% • Functional analysis is a significantly better predictor of dislocating/ squeaking hips than static assessments
Patient Image Functional FHA imaging processing analysis report Low dose CT scan Segmentation, Analysis using kinematic Results presented in Functional X-Rays landmarking and 3D parameters Functional Hip Analysis implant positioning report
Functional X-rays 1. Standing 2. Flexed Seated 3. Contralateral leg raise
Functional X-rays 1. Standing 2. Flexed Seated 3. Contralateral leg raise
Functional X-rays 1. Standing 2. Flexed Seated 3. Contralateral leg raise
Edge loading Dynamic motion
Delivery tools The guide Cup orientation is ideal for a PSI type solution Not compromised by unknown pelvic position on the table
Case Study 1 S upine Pelvic Tilt 1.7° Flexion Risk
Case Study 1
Case Study 2 S upine Pelvic Tilt 3.6° S upine Pelvic Tilt 3.6°
Case Study 2 S upine Pelvic Tilt 3.6° S upine Pelvic Tilt 3.6° Extension Risk
Case Study 2
S ummary • Variations in sagittal pelvic rotation have a substantial effect on the functional anteversion and inclination of the acetabular cup in flexion and extension. • Optimal cup orientation is likely patient-specific - previously defined static ‘ safe zones’ might not be appropriate for all patients. • Functional analysis may be a significantly better predictor of dislocating/ squeaking hips than static assessments.
Thank Y ou
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