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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_11 | Pages 11 - 11
1 Jun 2016
O'Neill C Molloy D Patterson C Beverland D
Full Access

Introduction

Radiological Inclination (RI) is defined as the angle formed between the acetabular axis and the longitudinal axis when projected onto the coronal plane. Higher RI angles are associated with adverse outcomes.

Methods

Primary aim: to investigate the effect of adjusting patient pelvic position in the transverse plane by using a ‘head-down’ (HD) operating table position. This was to determine, when aiming for 35° Apparent Operative Inclination (AOI), which operating table position most accurately achieved a target post-operative RI of 42°.

N=270. Patients were randomised to one of three possible operating table positions:

0°HD (Horizontal),

7°HD, or

Y°HD (Patient Specific Table Position)

Operating table position was controlled using a digital inclinometer. RI was measured using EBRA software.


The Bone & Joint Journal
Vol. 98-B, Issue 1_Supple_A | Pages 37 - 43
1 Jan 2016
Beverland DE O’Neill CKJ Rutherford M Molloy D Hill JC

Ideal placement of the acetabular component remains elusive both in terms of defining and achieving a target. Our aim is to help restore original anatomy by using the transverse acetabular ligament (TAL) to control the height, depth and version of the component. In the normal hip the TAL and labrum extend beyond the equator of the femoral head and therefore, if the definitive acetabular component is positioned such that it is cradled by and just deep to the plane of the TAL and labrum and is no more than 4mm larger than the original femoral head, the centre of the hip should be restored. If the face of the component is positioned parallel to the TAL and psoas groove the patient specific version should be restored. We still use the TAL for controlling version in the dysplastic hip because we believe that the TAL and labrum compensate for any underlying bony abnormality.

The TAL should not be used as an aid to inclination. Worldwide, > 75% of surgeons operate with the patient in the lateral decubitus position and we have shown that errors in post-operative radiographic inclination (RI) of > 50° are generally caused by errors in patient positioning. Consequently, great care needs to be taken when positioning the patient. We also recommend 35° of apparent operative inclination (AOI) during surgery, as opposed to the traditional 45°.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):37–43.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_12 | Pages 32 - 32
1 Nov 2015
O'Neill C Molloy D Patterson C Beverland D
Full Access

Introduction

Operative inclination (OI) is defined as the angle between the acetabular axis and the sagittal plane. With the patient in the true lateral decubitus position, this corresponds to the angle formed between the handle of the acetabular component inserter and the theatre floor intra-operatively.

Patients/Materials & Methods

The primary study aim was to determine which method of acetabular component insertion most accurately allows the surgeon to obtain a target OI of 35o.

270 consecutive patients undergoing cementless THA were randomised to one of three possible methods for acetabular component implantation:

1. Freehand,

2. 35o mechanical alignment guide (MAG), or

3. Digital inclinometer assisted

Two surgeons participated. Target OI was 35o in all cases. OI was measured using a digital inclinometer. For the freehand and MAG cases, the surgeon was blinded to inclinometer readings intra-operatively.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 7 | Pages 883 - 886
1 Jul 2006
Archbold HAP Mockford B Molloy D McConway J Ogonda L Beverland D

Ensuring the accuracy of the intra-operative orientation of the acetabular component during a total hip replacement can be difficult. In this paper we introduce a reproducible technique using the transverse acetabular ligament to determine the anteversion of the acetabular component. We have found that this ligament can be identified in virtually every hip undergoing primary surgery. We describe an intra-operative grading system for the appearance of the ligament. This technique has been used in 1000 consecutive cases. During a minimum follow-up of eight months the dislocation rate was 0.6%. This confirms our hypothesis that the transverse acetabular ligament can be used to determine the position of the acetabular component. The method has been used in both conventional and minimally-invasive approaches.