A retrospective study of patients treated over 10 years found that longer Kirschner wires and single-knot constructs were associated with a higher risk of failure in tension band wiring for transverse patellar fractures.
Researchers reviewed data from 32 patients who underwent surgical treatment for transverse patellar fractures using classic tension band wiring (TBW) from 2013 to 2022. Among them, 9 patients (28.1%) experienced failure. Of these, six were due to cerclage wire slippage and three were from wire breakage. The median time to failure was 58 days, with slippage occurring at a median of 33 days postoperatively.
Radiographic parameters were assessed to identify predictors of failure. Longer Kirschner wires (K-wires) length was significantly associated with TBW failure. The mean K-wire length in the failure group was 77.75 mm, compared with 65.35 mm in the non-failure group. ROC analysis identified a cutoff of 69.1 mm, with an area under the curve (AUC) of 0.785, sensitivity of 77.8%, and specificity of 73.9%.
The patella-to–K-wire length ratio was also significantly lower in the failure group (0.70) compared to the non-failure group (0.77), indicating potential mismatch between implant length and bone anatomy.
Knot configuration was another predictor of failure. Single-knot constructs had a failure rate of 66.7%, while double-knot constructs had a 19.2% failure rate. Logistic regression showed that failure was 8.4 times more likely in the single-knot group (odds ratio, 0.119).
Lateral placement of the K-wire relative to the articular surface also influenced outcomes. In the slippage group, the mean lateral K-wire distance to the articular surface was 12.15 mm, compared to 9.54 mm in the non-slippage group. ROC analysis determined a cutoff value of 10.85 mm (AUC, 0.792), with 83.3% sensitivity and 73.1% specificity.
The ratio between lateral K-wire distance and patellar thickness was significantly higher in the slippage group (0.48) than in the non-slippage group (0.41). The cutoff value was 0.45, with an AUC of 0.676, sensitivity of 83.3%, and specificity of 65.4%.
The mean patient age was 50 years (range, 26–80). The cohort included 24 men (75%) and 8 women (25%). Failure was not associated with sex, body mass index, or height. However, patients who experienced failure had significantly higher body weight (88.5 kg vs 77.86 kg).
Injury mechanisms included traffic accidents, high-energy falls, and work-related trauma. The researchers focused exclusively on AO Type 34-C1 fractures treated with classic TBW.
The authors reported no conflicts of interest.
