The First SICOT Oral Presentation Award 2011: Imageless computer-assisted femoral component positioning in hip resurfacing: a prospective randomised trial

Abstract

Purpose The aim of the study was to evaluate the effects of imageless computer-assisted surgery (CAS) on the accuracy of positioning of the femoral component and on the shortterm clinical outcome in hip resurfacing (HR) using a randomised prospective design. Methods A total of 75 consecutive patients undergoing HR were randomly allocated to CAS and conventional implantation, respectively. Preoperatively and six months postoperatively standardised pelvic anteroposterior X-ray images, the total Western Ontario and McMaster Universities Osteoarthritis Index, the Harris Hip Score and the EQ-5D utility index were evaluated in a blinded manner. The primary end point of the study was a post-operative femoral component malpositioning in five degrees or more either varus or valgus absolute deviation from the planned stem shaft angle. Results Patient demographics and algofunctional scores did not differ between the CAS and conventional implantation samples. Using CAS fewer femoral components were positioned in five or more degrees absolute deviation (4/37 vs 12/38, Fisher's exact p=0.047; 95 % confidence interval for the primary end point's incidence difference: +3 %; +39 %); the respective incidences of five or more degrees of varus deviation were 0/37 vs 5/38. One conversion to a stemmed prosthesis (CAS group) was performed for periprosthetic femoral neck fracture. Radiological signs of superolateral femoral neck/implant impingement were observed in two cases (one CAS-based and one conventional implantation). Conclusions The accuracy of femoral HR component positioning was significantly improved using CAS. However, one major complication necessitated early revision in the CAS group at six months of observation. Apart from that adverse event no inter-group differences were observed for the short-term clinical outcome. Future studies need to address the clinical long-term relevance of CAS in HR.

No added value for Computer-Assisted surgery to improve femoral component positioning and Patient Reported Outcomes in Hip Resurfacing Arthroplasty; a multi-center randomized controlled trial

“…We did observe an overall improvement of patients’ functioning over time, but this was similar for the two treatment groups. All results are consistent with previous studies [9, 19, 37].…”

“…In contrast to our results, Stiehler et al, did show a significant improvement in placement of the femoral component with the use of CAS. Fewer femoral components were positioned in ≥5 degrees absolute deviation compared to preplanning in the CAS group [19]. In another, retrospective study, they showed a more accurate placement of the femoral component and less deviations from the planned SSA was accomplished with the use of CAS [37].…”

Effect of surgical experience on imageless computer-assisted femoral component positioning in hip resurfacing – a preclinical study

“…Similar findings were published by Resubal and Morgan: in their study, none vs. 31 of 131 (24%) outliers occurred in the CAS and conventional group, respectively [ 21 ]. A cadaver study performed by Davis et al showed that surgeons tend to implant the femoral cap in varus orientation with a deviation up to 15° when using the manual jig, whereas this deviation was reduced to a maximum of 8° by the use of CAS [ 22 , 23 ]. Furthermore, we previously compared the same CAS system and conventional free-hand technique as evaluated in the present study in a prospectively randomized clinical trial and found that CAS significantly reduced the rate of outliers with five or more degrees of absolute deviation (4/37 vs. 12/38, respectively, Fisher’s exact P = 0.047) [ 23 ].…”

“…A cadaver study performed by Davis et al showed that surgeons tend to implant the femoral cap in varus orientation with a deviation up to 15° when using the manual jig, whereas this deviation was reduced to a maximum of 8° by the use of CAS [ 22 , 23 ]. Furthermore, we previously compared the same CAS system and conventional free-hand technique as evaluated in the present study in a prospectively randomized clinical trial and found that CAS significantly reduced the rate of outliers with five or more degrees of absolute deviation (4/37 vs. 12/38, respectively, Fisher’s exact P = 0.047) [ 23 ]. In addition, that study demonstrated a reduced incidence of varus outliers exceeding 5° by CAS (0/37 vs. 5/38 for CAS and control group, respectively, P = 0.054).…”