Implant choice was changed from cemented Thompson to Exeter Trauma Stem (ETS) for treatment of displaced intra-capsular neck of femur fractures in University Hospital Aintree, Liverpool, United Kingdom (a major trauma center), following the NICE guidelines that advised about the use of a proven femoral stem design rather than Austin Moore or Thompson stems for hemiarthroplasties. The aim of our study was to compare the results of Thompson versus ETS hemiarthroplasty in Aintree. We initially compared 100 Thompson hemiarthroplasties that were performed before the start of ETS use, with 100 ETS hemiarthroplasties. There was no statistically significant difference between the two groups in terms of patients' demographics (age, sex and ASA grade), intra-operative difficulties/complications, post op medical complications, blood transfusion, in-patient stay and dislocations. The operative time was statistically significantly longer in the ETS group (p= .0067). Worryingly, the 30 days mortality in ETS group was more than three times higher in ETS group (5 in Thompson group versus 16 in ETS group. P= .011). To corroborate our above findings we studied 100 more consecutive patients that had ETS hemiarthroplasty. The results of this group showed 30 day mortality of 8 percent. However the operative time was again significantly longer (p= .003) and there was 18 percent conversion to bipolar hemiarthropalsty. Moreover there was statistically significant increased rate of deep infection (7%, p = .03) and blood transfusion (27%, p = .007). This we feel may be due to longer and more surgically demanding operative technique including pressurised cementation in some patients with significant medical comorbidities. Our results raise the question whether ETS hemiarthoplasty implant is a good implant choice for neck of femur fracture patients. Randomised control trials are needed to prove that ETS implant is any better than Thompson hemiarthroplasty implants in this group of patients.
For the bilaterally normal group the mean hip rotation was 2.9 degrees internal (SD 11.8). For the arthroplasty group the mean rotation on the normal and operated sides were 9.4 degrees external (SD 9.5) and 6.9 degrees internal (SD 13.9) respectively. In this group there was a significant difference between the normal and operated side (P= 0.02).
An electromagnetic tracking system was used to measure the flexion in the operated and normal hip of each patient. Tracker sensors were placed on the iliac crest and the mid-lateral thigh. The patients were then asked to flex forward from a standing position to pick an object up off the floor. This movement was repeated 3 times. Flexion data was collected at 10Hz which was accurate to 0.15 degrees. Spinal flexion was not recorded during the task. Patients were also asked to complete the Harris and Oxford Hip Score questionnaires to obtain qualitative data regarding their hip replacement.
Small bearing group:
Operated side: Peak flexion = 79.3 Normal side: Peak flexion = 83.4. Thus the bilateral difference for peak flexion was 4.1 (paired t-test, P=0.12). Large bearing group: Operated side: Peak Flexion = 72.7. Normal side: Peak Flexion = 74.0 Thus the bilateral difference for peak flexion was 1.3 (paired t-test, P= 0.83). Comparing the small bearing group with the large bearing group, the peak difference was 6.6. This difference was non-significant with P = 0.43. All patients reported good – excellent functional results when completing the Harris and Oxford Hip Scores.