Candy box technique with sutures and Nice knot: a novel approach to inferior pole patellar fractures

Abstract

Aims: Our study explores the candy box (CB) technique with sutures and Nice knot as a novel treatment for inferior pole patellar fractures, potentially superior to traditional wire fixation. Methods: CT data from five adult knee joints were extracted to create finite element models for inferior pole patellar fractures and four internal fixation models. These included CB technique combined with high-strength sutures and Nice knot (CB-H), CB technique combined with tendon sutures and Nice knot (CB-T), CB technique combined with steel wires (CB-S), and tension-band wiring combined with cerclage wiring (TBWC). Displacement and stress distribution during knee flexion and extension were compared. Physical models were created using 3D printing technology. These models were then subjected to static tensile test and dynamic fatigue test. Data from 21 patients treated with CB-H and 22 patients treated with TBWC were analyzed to assess the effectiveness. Results: Finite element analysis (FEA) indicated that displacements for CB-H and CB-T were below the failure threshold in all knee joint states. Stresses on the patella and internal fixation were lower in the CB-H and CB-T groups compared with the CB-S and TBWC groups. Both static and dynamic biomechanical experiments confirmed that displacements of CB-H and CB-T also remained below the failure threshold. In clinical research, the CB-H group outperformed the TBWC group in operating time, intraoperative blood loss, length of incision and time to clinical union, and complication control. Conclusion: The CB technique combined with sutures and Nice knot can provide sufficient fixation strength for inferior pole patellar fractures. This method enables early functional exercise and avoids the need for secondary surgery. It could be a promising alternative to traditional TBWC surgery. Cite this article: Bone Joint Res 2025;14(8):721–734.

Keywords

• candy box technique
• biomechanical experiments
• clinical research
• sutures
• internal fixations
• strength
• patella
• patellar fractures
• knee joints
• fatigue
• tendon
• intraoperative blood loss
• finite element models