gms | German Medical Science

Objectives: Intraoperative periprosthetic fractures (IPF) are a well described complication following total hip arthroplasty as well as hemiarthroplasty. Uncemented fixation of the femoral stem has been previously shown to be a significant risk factor (Taylor et al. 2012; Langslet et al. 2014). Our aim was to identify other risk factors as well as to characterise the fractures that occurred intraoperatively. Finally, we investigated whether postoperative mobility was increasingly impaired in case of IPF.

Methods: In our clinic, we retrospectively reviewed 481 bipolar hemiarthroplasties for displaced femoral neck fractures from January 2013 to March 2018. 421 (87.5%) procedures were done without cement. 407 (84.6%) procedures were performed using the Zweymüller Alloclassic ® stem. Data on patients' demographics, comorbidities, surgical approach, femoral canal geometry (Dorr Canal Type, Canal Flare Index), surgeon's experience (junior vs. senior surgeon) and timing of surgery (daytime vs. on-call-duty) was obtained. In case of intraoperative fracture, further information was obtained. Patients' mobility was assessed by questionnaire or subsequent telephone interview using a matched pair analysis. Mobility was classified according to the NHFD mobility score. Statistical analysis was performed using SPSS. Chi-square test, Fisher's exact test and Fisher-Freeman-Halton Exact Test were used for comparison between categorical variables, while Mann-Whitney U test was used for continuous variables.

Results and conclusion: Out of 481 procedures, 34 (7.1%) IPF were identified. One significant risk factor could be found which was Dorr Canal Type C (p=.004). Other risk factors included female gender (OR 2.30, 95% CI .872-6.079), stovepipe femur (OR 1.749, 95% CI .823-3.713), junior surgeon (OR 1.204, 95% CI .596-2.432) as well as on-call-duty surgery (OR 1.471, 95% CI .711-3.046), although neither showed a significant difference. Uncemented hemiarthroplasty was not a significant risk factor, neither (p=.104; OR 5.018, 95% CI .674-37.384), however there was only one IPF in 60 cemented procedures (1.67%). Out of 34 IPF, 25 (73.5%) were identified as Vancouver Type A. Treatment of choice was cerclage wiring in a figure of 8 fashion. Within the 12 pairs identified through matched pair analysis, 8 were Vancouver type A, 3 type B and one type C. Overall, postoperative mobility difference was .41 points to the disadvantage of the IPF group. When isolating type A fractures, the point differential was .62.

IPF is a complication not infrequently encountered with uncemented hemiarthroplasty. Identification of risk factors preoperatively is crucial in order to avoid fractures. In case of a Dorr type C femur, cemented fixation should be favored. When an intraoperative fracture does occur and adequate treatment is performed, chances are that outcomes in the short and mid-term are similar when compared to non-fracture cases.