Periprosthetic fractures of the distal femur (PPDFs) above a total knee arthroplasty (TKA) are challenging to manage. Further, substantial controversy exists regarding the ideal fixation strategy, with locked plating (LP) and retrograde intramedullary nailing (RIMN) being the two favoured constructs. Given the debate regarding the optimal management of this injury, we conducted a multi-centre randomized controlled trial of LP versus RIMN for the treatment of PPDFs. This prospective, multi-centre randomized controlled trial compared LP to RIMN for the management of PPDFs. Between 2014–2022, patients were recruited from thirteen trauma centres in Canada, the USA and Spain. Patients meeting inclusion criteria were randomized to either LP or RIMN via block randomization with stratification based on a pre-operative diagnosis of osteoporosis and were followed for two years post-intervention. Our primary outcome was the timed up and go (TUG) test at 3 months. Secondary outcomes included the Knee Society Score (KSS), rates of nonunion, malunion, re-operation, and mortality. Malunions were defined as fractures healing with greater than five degrees of malalignment in any plane or those with greater than one centimeter of shortening. We calculated a desired sample of size of 47 patients in each group (94 patients total) in order to detect a clinically significant difference in TUG scores and accounting for 10% loss to follow-up. Of the 94 patients randomized, 53 were randomized to LP and 41 to RIMN. Follow-up data for our primary outcome was available for 82% of patients. No significant differences were observed between groups on the TUG test at 3 months (56.5±57.0 seconds in the LP group vs 50.0±51.5 seconds in the RIMN group, p = 0.62), or any time point thereafter (see Figure 1). Similarly, no significant differences were observed in KSS scores at any time point. Nonunion occurred in 3/40 (7.5%) of patients in the LP group at one year versus 0/30 (0%) patients in the RIMN group (p = 0.25, see Figure 2). Malunion was less common in the LP group 4/43 (9.3%) vs the RIMN group 13/36 (36.1%) (p = 0.003, see Figure 2). Reoperation occurred in 5/40 (12.5%) patients in the LP group at one year versus 1/30 (3.3%) patients in the RIMN group (p = 0.23). Mortality rates were similar in both groups at one year (13% LP group versus 14.3% RIMN group, p = 1.0). This multicentered, international, randomized controlled trial of LP versus RIMN for the treatment of PPDFs did not demonstrate any significant differences between the two fixation strategies with respect to functional outcomes. However, differences in healing were found. Malunion was significantly more common in the RIMN group, while nonunion and re-operation occurred more frequently in the LP group, although the differences were not significant and both events were infrequent. Overall, both LP and RIMN are acceptable treatment options for the management of PPDFs above a TKA. For any figures or tables, please contact the authors directly.
Nauth et al. (Wed,) studied this question.