High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming- A CT Based Anatomical Study

Christian Merle, Moritz Innmann, Wenzel Waldstein, Elise Pegg, Peter R Aldinger, Harinderjit Gill, David W. Murray, George Grammatopoulos

Research output: Contribution to journalArticle

Abstract

Background:

The objectives of the present study were to (1) evaluate the accuracy and reliability of native acetabular offset measurements performed on conventional supine anterior-posterior (ap) pelvis radiographs with reference to computed tomography (CT) in patients with end-stage hip osteoarthritis (OA); (2) determine the minimum and maximum amount of medialisation of the centre of rotation (COR) simulating different reaming techniques for acetabular preparation; and (3) identify patients at increased risk of excessive medialisation of the COR.

Methods:

A consecutive series of corresponding 131 CT scans and radiographs of patients with primary hip osteoarthritis was evaluated using validated software for 3D measurements. Acetabular and femoral parameters were evaluated. We simulated the implantation of a hemispherical press-fit cup comparing anatomical and conventional reaming techniques and assessed corresponding changes in acetabular offset. A medialization greater than 8mm was considered as clinically relevant.

Results:

Standardised ap pelvis radiographs allowed for an accurate and reliable assessment of acetabular offset compared to CT based measurements. Cup placement in the most lateral position (anatomical reaming technique) resulted in a mean implant-related medialization of 5.9±3.4 mm. On average, the most medial aspect of the cup remained at the level of the acetabular “true floor”; however, anatomical cup placement did not require reaming to the true floor in 64 hips (49%). With the conventional reaming technique, the total medialization of the COR (implant-related and reaming-related) was 6.8±2.9, with 34% of cases having a medialization ≥8 mm. There was no difference in the number of patients with high FO and Dorr type A femora at high risk for excessive reaming between anatomical- (16%) and conventional (24%) reaming.

Conclusions:

The present study quantifies potential changes of native COR with different acetabular reaming techniques and highlights the variability of acetabular anatomy in patients with primary OA. Acetabular offset can be accurately and reliably determined on conventional ap pelvis radiographs and appears to be independent of femoral shape or geometry. Depending on the preferred reaming technique a substantial number of patients appear at risk for excessive cup medialisation. The present findings support the use of pre-operative AO assessment and templating in order to improve individual restoration of hip offset in patients with primary hip OA.
LanguageEnglish
JournalJournal of Arthroplasty
Early online date1 Apr 2019
DOIs
StatusE-pub ahead of print - 1 Apr 2019

Fingerprint

Hip Osteoarthritis
Hip Dislocation
Femur
Thigh
Cohort Studies
Anatomy
Neck
Osteoarthritis
Leg
Body Mass Index

Keywords

  • anatomy
  • proximal femur
  • hip
  • osteoarthritis
  • dysplasia

Cite this

High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming- A CT Based Anatomical Study. / Merle, Christian; Innmann, Moritz; Waldstein, Wenzel; Pegg, Elise; Aldinger, Peter R; Gill, Harinderjit; Murray, David W.; Grammatopoulos, George.

In: Journal of Arthroplasty, 01.04.2019.

Research output: Contribution to journalArticle

Merle, Christian ; Innmann, Moritz ; Waldstein, Wenzel ; Pegg, Elise ; Aldinger, Peter R ; Gill, Harinderjit ; Murray, David W. ; Grammatopoulos, George. / High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming- A CT Based Anatomical Study. In: Journal of Arthroplasty. 2019.
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abstract = "Background:The objectives of the present study were to (1) evaluate the accuracy and reliability of native acetabular offset measurements performed on conventional supine anterior-posterior (ap) pelvis radiographs with reference to computed tomography (CT) in patients with end-stage hip osteoarthritis (OA); (2) determine the minimum and maximum amount of medialisation of the centre of rotation (COR) simulating different reaming techniques for acetabular preparation; and (3) identify patients at increased risk of excessive medialisation of the COR.Methods:A consecutive series of corresponding 131 CT scans and radiographs of patients with primary hip osteoarthritis was evaluated using validated software for 3D measurements. Acetabular and femoral parameters were evaluated. We simulated the implantation of a hemispherical press-fit cup comparing anatomical and conventional reaming techniques and assessed corresponding changes in acetabular offset. A medialization greater than 8mm was considered as clinically relevant.Results:Standardised ap pelvis radiographs allowed for an accurate and reliable assessment of acetabular offset compared to CT based measurements. Cup placement in the most lateral position (anatomical reaming technique) resulted in a mean implant-related medialization of 5.9±3.4 mm. On average, the most medial aspect of the cup remained at the level of the acetabular “true floor”; however, anatomical cup placement did not require reaming to the true floor in 64 hips (49{\%}). With the conventional reaming technique, the total medialization of the COR (implant-related and reaming-related) was 6.8±2.9, with 34{\%} of cases having a medialization ≥8 mm. There was no difference in the number of patients with high FO and Dorr type A femora at high risk for excessive reaming between anatomical- (16{\%}) and conventional (24{\%}) reaming.Conclusions:The present study quantifies potential changes of native COR with different acetabular reaming techniques and highlights the variability of acetabular anatomy in patients with primary OA. Acetabular offset can be accurately and reliably determined on conventional ap pelvis radiographs and appears to be independent of femoral shape or geometry. Depending on the preferred reaming technique a substantial number of patients appear at risk for excessive cup medialisation. The present findings support the use of pre-operative AO assessment and templating in order to improve individual restoration of hip offset in patients with primary hip OA.",
keywords = "anatomy, proximal femur, hip, osteoarthritis, dysplasia",
author = "Christian Merle and Moritz Innmann and Wenzel Waldstein and Elise Pegg and Aldinger, {Peter R} and Harinderjit Gill and Murray, {David W.} and George Grammatopoulos",
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T1 - High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming- A CT Based Anatomical Study

AU - Merle, Christian

AU - Innmann, Moritz

AU - Waldstein, Wenzel

AU - Pegg, Elise

AU - Aldinger, Peter R

AU - Gill, Harinderjit

AU - Murray, David W.

AU - Grammatopoulos, George

PY - 2019/4/1

Y1 - 2019/4/1

N2 - Background:The objectives of the present study were to (1) evaluate the accuracy and reliability of native acetabular offset measurements performed on conventional supine anterior-posterior (ap) pelvis radiographs with reference to computed tomography (CT) in patients with end-stage hip osteoarthritis (OA); (2) determine the minimum and maximum amount of medialisation of the centre of rotation (COR) simulating different reaming techniques for acetabular preparation; and (3) identify patients at increased risk of excessive medialisation of the COR.Methods:A consecutive series of corresponding 131 CT scans and radiographs of patients with primary hip osteoarthritis was evaluated using validated software for 3D measurements. Acetabular and femoral parameters were evaluated. We simulated the implantation of a hemispherical press-fit cup comparing anatomical and conventional reaming techniques and assessed corresponding changes in acetabular offset. A medialization greater than 8mm was considered as clinically relevant.Results:Standardised ap pelvis radiographs allowed for an accurate and reliable assessment of acetabular offset compared to CT based measurements. Cup placement in the most lateral position (anatomical reaming technique) resulted in a mean implant-related medialization of 5.9±3.4 mm. On average, the most medial aspect of the cup remained at the level of the acetabular “true floor”; however, anatomical cup placement did not require reaming to the true floor in 64 hips (49%). With the conventional reaming technique, the total medialization of the COR (implant-related and reaming-related) was 6.8±2.9, with 34% of cases having a medialization ≥8 mm. There was no difference in the number of patients with high FO and Dorr type A femora at high risk for excessive reaming between anatomical- (16%) and conventional (24%) reaming.Conclusions:The present study quantifies potential changes of native COR with different acetabular reaming techniques and highlights the variability of acetabular anatomy in patients with primary OA. Acetabular offset can be accurately and reliably determined on conventional ap pelvis radiographs and appears to be independent of femoral shape or geometry. Depending on the preferred reaming technique a substantial number of patients appear at risk for excessive cup medialisation. The present findings support the use of pre-operative AO assessment and templating in order to improve individual restoration of hip offset in patients with primary hip OA.

AB - Background:The objectives of the present study were to (1) evaluate the accuracy and reliability of native acetabular offset measurements performed on conventional supine anterior-posterior (ap) pelvis radiographs with reference to computed tomography (CT) in patients with end-stage hip osteoarthritis (OA); (2) determine the minimum and maximum amount of medialisation of the centre of rotation (COR) simulating different reaming techniques for acetabular preparation; and (3) identify patients at increased risk of excessive medialisation of the COR.Methods:A consecutive series of corresponding 131 CT scans and radiographs of patients with primary hip osteoarthritis was evaluated using validated software for 3D measurements. Acetabular and femoral parameters were evaluated. We simulated the implantation of a hemispherical press-fit cup comparing anatomical and conventional reaming techniques and assessed corresponding changes in acetabular offset. A medialization greater than 8mm was considered as clinically relevant.Results:Standardised ap pelvis radiographs allowed for an accurate and reliable assessment of acetabular offset compared to CT based measurements. Cup placement in the most lateral position (anatomical reaming technique) resulted in a mean implant-related medialization of 5.9±3.4 mm. On average, the most medial aspect of the cup remained at the level of the acetabular “true floor”; however, anatomical cup placement did not require reaming to the true floor in 64 hips (49%). With the conventional reaming technique, the total medialization of the COR (implant-related and reaming-related) was 6.8±2.9, with 34% of cases having a medialization ≥8 mm. There was no difference in the number of patients with high FO and Dorr type A femora at high risk for excessive reaming between anatomical- (16%) and conventional (24%) reaming.Conclusions:The present study quantifies potential changes of native COR with different acetabular reaming techniques and highlights the variability of acetabular anatomy in patients with primary OA. Acetabular offset can be accurately and reliably determined on conventional ap pelvis radiographs and appears to be independent of femoral shape or geometry. Depending on the preferred reaming technique a substantial number of patients appear at risk for excessive cup medialisation. The present findings support the use of pre-operative AO assessment and templating in order to improve individual restoration of hip offset in patients with primary hip OA.

KW - anatomy

KW - proximal femur

KW - hip

KW - osteoarthritis

KW - dysplasia

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M3 - Article

JO - Journal of Arthroplasty

T2 - Journal of Arthroplasty

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SN - 0883-5403

ER -