David Mitchell & Shaun English have attended the Combined British and Italian Hip Society Conference, Milan, November 2015.

The debate on the anterior approach for hip replacement continues.  By approach, I mean whether the skin incision is behind, beside, or in front of the hip joint.  There has an underlying assumption that the new anterior approach has a faster recovery and lower dislocation rate.  Neither of these assertions are proven, indeed the length of hospitalisation seen in Ballarat with the mini posterior approach average 1.7 days last year, in contrast to the papers presented at the conference averaged 4.5-9.2 days.  Papers presented included dislocation rates of zero through to 2.5% with anterior approaches including the so called bikini approach.

Complications that are less commonly discussed are damage to the lateral cutaneous nerve of thigh (16%) and heterotopic ossification (21%) with the “new approaches” which we previously did not see with the mini-posterior approach. The paper mentioning nerve injury was on the learning curve looking at the first 30 cases in each institution, and noted numbness over the outer aspect of the thigh is often transient, and not problematic.  We have seen cases of “dysasthesia”, a more permanent unpleasant sensation over the outer thigh that persists after anterior approach.

Heterotopic ossification can cause stiffness of the hip replacement.  In the paper discussing this complication they felt that the clinical results were no different in the 21% of patients having unexpected bone formation on the followup XR. In our series of mini posterior approach, we rarely see heterotypic ossification.  We don’t know if this is an approach specific improvement, or our routine use of COX-2 NSAIDs such as meloxicam.

An interesting evolution is using the direct anterior approach for patients with neck of femur fractures.  This is a group where the dislocation rate for previous operations has been problematic.  Surprisingly, the incidence of fracture around the hip replacement stem was low for this group of patients, and this may be a worthy area to introduce this approach.

In conclusion: we accept the anterior approach has potential, but so far it doesn’t seem to universally better, and carries some new risks.

References
1. Trono M et al, “Learning curve for mini-invasive anterior hip approach: multicentric study”     HIP International, 2015, Volume 25, supp 1. S10
2. Basso M et al, “Is minimally invasive anterior approach to the hip related to high risk of heterotypic ossification?  A clinical and radiological assessment”
HIP International, 2015, Volume 25, supp 1. pS70
3. Mortazavi S et al “Bipolar hemiarthroplasty using anterior approach in elderly patients with femoral neck fracture – faster rehabilitation, less complications”.  HIP International, 2015, Volume 25, supp 1. S55