Introduction: The anterior and anterolateral approach to the hip traditionally are well described exposures in primary hip arthroplasty with fewer dislocations than the posterior approach. A very debilitating complication associated with the anterolateral approach however is the persistent limp and positive Trendelenburg sign. We discuss our results with respect to abductor function and morphological integrity seen on MRI when using an approach in which we preserve the majority of gluteus medius.

Methods: We carried out a prospective study of thirty-nine consecutive total hip replacements performed through a gluteus medius sparing anterolateral approach. The same hip surgeon performed all these between April and October 2004. Gait analysis and Trendelenburg tests were evaluated during clinical follow-up at six weeks and three months. Coronal STIR and T1 weighted MRI sequences of the abductors were performed between four and six weeks and the findings were agreed by the consensus of two radiologists.

Results: At three-month follow-up all thirty-nine patients tested Trendelenburg negative. Post-operative radiographs showed satisfactory femoral and acetabular component position. MRI findings showed the gluteus medius tendon to be intact with no shortening on T1. Artefacts were found to be less marked in the higher field strength magnet but more apparent in the STIR weighted sequences.

Discussion: We have tried to incorporate the advantages of reduced dislocation rate of the anterolateral approach, whilst avoiding violation of the abductors. The clinical result and radiographic findings we have presented suggest that the described exposure is an effective and safe method of approaching the hip, with minimal disruption of the abductor mechanism. In addition to maintaining the reduced dislocation rate associated with the standard anterolateral approach. Intact abductor function allows for rapid rehabilitation.

Scientific Background The Coracoid process of scapula is a principal landmark in shoulder surgery. Brachial plexus is at risk of injury during surgery around the coracoid, e.g. Weaver-Dunn procedure. Magnetic resonance imaging is the method of choice for evaluating the anatomy and pathology of the brachial plexus and has good resolution compared to Computed tomography or Ultrasound (Ref: 1).

Aim The aim was to study the proximity of brachial plexus to coracoid process in various Shoulder positions. The objective was to define the position of safety for operating around the coracoid.

Methods With Ethics Committee approval, twelve healthy volunteers (men with average age of thirtyfive years) were recruited. Exclusion criteria included previous shoulder injury or operations, known contra-indication for MRI examination and children. An open Magnetic Resonance Scanner (1.5 Teslar) was used to facilitate shoulder positioning. Consent was obtained prior to scanning after information was given to subjects. They were placed under the scanner and images were obtained in axial, coronal and sagittal plane with shoulder in neutral, 45 degrees and 90 degrees of abduction. The images taken are T1, T2 axial spin-echo sequences with 2-mm cuts and coronal echo of a T1-3D gradient with 2 mm cuts, together with a T1 coronal spin-echo, with cuts 2 mm in width. Distance from coracoid process to the Brachial plexus bundle is measured in millimetre on the PACS system which has software to eliminate magnification.

Results The brachial plexus consistently moved away medially from the coracoid in all the subjects at 45 degrees abduction of the shoulder. It returned to the closer position to coracoid in 90Degree abduction. The statistical analysis showed that on an average the distance the brachial plexus moved away towards medial side by 4.37 mm with Standard deviation 3.57 (p= 0.014).

Conclusion The brachial plexus move medially away from coracoid process at 45 degrees shoulder abduction. This position reduces the risk of injury to the brachial plexus during surgery around the coracoid process.