Total hip replacement is considered one of the most successful orthopaedic procedure and has high patient satisfaction rate (Learmonth, Young and Rorabeck, 2007). As per the UK National joint registry, the 15-year revision rate for a cemented hip replacement is 5.46 % (Reports.njrcentre.org.uk, 2020). At the time of revision hip replacement surgery, removal of components of a cemented hip replacement requires specialised skills and instruments (Kraay, 2015). The most common surgical technique described in the literature is ETO (extended trochanteric osteotomy) (Masri, Mitchell and Duncan, 2005). The ETO can also be used to correct varus femoral deformity, which is secondary to bone remodelling around a loose femoral component (VALLE et al., 2003). But the current literature suggests that ETO is also associated with complication such as arterial injury, intra and post-operative fractures, proximal migration of osteotomy fragment and non-union (Wronka et al., 2020).
There have been several versions of cortical osteotomy described in the literature for extraction of the broken femoral stem (Akrawi et al., 2014) or removal of cemented/uncemented femoral stem (Harada and Fujita, 2016). But these are the technique described in a case report or in the form of a case series with smaller sample size and limited follow up. This affects the external validity of these studies. There is also a lack of insight into the long-term consequences of these techniques, such as implant subsidence or loosening.
Park et al., (2019) described their version of anterior cortical window technique for removal of the femoral stem during revision arthroplasty. In this study, the implant subsidence rate was 8.4% (within one year of surgery), and non-union rate for the cortical window was 2%. The reoperation rate was also significantly high, i.e. 21.4% due to factors such as loosening of the femoral stem and acetabular cup, bursitis related to cerclage wire, periprosthetic femur fracture, prosthetic joint infection and superficial wound infection. The technique is also different from ours as the length of the window is almost equal to an ETO, extending from the shoulder of the stem to the end of cement restrictor. This technique does warrant patients mobilise with protective weight-bearing over operated limb for six weeks. In our study, all cortical windows united mainly due to the smaller size of the window in addition to the meticulous surgical technique. The bevelled edge created by angulating the saw while making the window increases the surface area, and once the window is reduced, it heals with primary healing (Marsell and Einhorn, 2011). The osteotomy was considered healed when cortical bridging was noticed on anterior-posterior and lateral radiographs (Fisher et al., 2018). We did not see a change in implant position in any of our patients during the follow-up, and all the patients were allowed full weight-bearing over revised hips.
Melmer et al., (2004) in their study described long anterolateral cortical window which is made near the tip of the stem. Unfortunately, the author fails to explain the methodology of deciding the site of the window. A window made far from the implant tip will require alteration and further extension. This can potentially increase the length of the window and also the associated risks such as periprosthetic fracture and implant subsidence. In their study, 5.8% of the patients had implant subsidence post osteotomy. To avoid such complications, we believe that it is crucial to mark the osteotomy site by assessing preoperative radiographs or CT scan as described in our surgical technique.
We acknowledge that there are limitations to this study. This is a retrospective case series and provides level IV evidence (Murad et al., 2018). But the follow up of almost 2 years of majority of the patients in this study, provide a strong evidence that this technique does not increases the risk of intraoperative fractures and implant failure.