Hypothesis
Adding a circumferential cerclage wire to tension band wiring stabilises displaced transverse patella fractures and aids healing.
What failed
Among 72 eligible patients, 27 treated with the added cerclage and 45 without, rates of fixation failure, nonunion and revision surgery were indistinguishable (p = 0.620 for each); the risk associations that did trend upwards were age over 60 or 70 and superficially placed K-wires, the last of which trended worse within the cerclage group itself.
Broken assumption
Adding fixation hardware makes the construct more stable.
Why
The authors conclude the extra wire may be needless and argue correct surgical technique, in particular K-wire depth and control of both wire ends, matters more.
From the published paper: Yang et al. BMC Musculoskeletal Disorders, 2018. ↗CC BY