A retrospective cohort study on prevalence of postoperative complications in comminuted patellar fractures: comparisons among stabilized with Cannulated-Screw, Kirschner-Wire, or Ring-Pin Tension Bands

BACKGROUND: Displaced patellar fractures are commonly treated with open reduction and fixation with several different types of tension-band (TB) constructs. The main objective of this study was to compare the prevalence of postoperative complications after surgical stabilization of comminuted patellar fractures with either a modified Kirschner-wire tension band (MKTB), a cannulated-screw tension band (CSTB), or a ring-pin tension band (RPTB). METHODS: We conducted a retrospective and consecutive cohort study of comminuted patellar fractures (n = 334) stabilized using a TB construct. Postoperative premature loss of reduction, infection, and skin breakdown were compared according to the type of TB constructs received (MKTB, CSTB, or RPTB). The rate of implant removal due to symptomatic hardware was also evaluated. RESULTS: Fixation failure rate was significantly different among the groups (P = 0.013), with failure rates of 4.7% observed in the MKTB group,14.5% in the CSTB group, and 4.9% in the RPTB group. Skin breakdown and infection were not significantly different among the groups (Ps > 0.05). Due to symptomatic hardware, 40.5% of the patients in the MKTB group, 22.9% in the CSTB group, and 24.3% in the RPTB group underwent implant removal (P = 0.004). After adjusting for age, gender, comorbidities, number of supplementary screws/K-wires, and use of cerclage cables, multivariate regression analysis revealed that CSTB contributed to a 2.08-times greater risk of fixation failure compared to RPTB, while MKTB and RPTB were similar in risk of failure. In addition, it was found that patients who underwent MKTB fixation were more than twice as likely to undergo implant removal for symptomatic hardware compared with RPTB (odds ratio = 2.11, 95% CI = 1.20 to 3.72; P = 0.010). CONCLUSIONS: RPTB have advantage over MKTB and CSTB fixation in terms of symptomatic hardware and premature failure, respectively. LEVEL OF EVIDENCE: Therapeutic Level III