PURPOSE: Subpectoral biceps tenodesis is a widely used surgical technique to relieve pain and restore function in the shoulder by securing the long head of the biceps tendon. This study aimed to evaluate the mechanical performance of three fixation techniques using cortical button, interference screw and keyhole methods by assessing their strength, durability and strain distribution, incorporating the novel application of digital image correlation (DIC). METHODS: Thirty fresh porcine bone-tendon specimens were allocated evenly among the fixation techniques. Biomechanical testing involved cyclic axial loading (10-100 N) for 500 cycles, followed by load-to-failure testing using a universal testing machine. DIC analysis assessed strain distribution around the bone drill site. Statistical comparisons of displacement, load-to-failure and strain patterns were performed. RESULTS: Cortical button fixation demonstrated the highest average load-to-failure at 353 ± 45 N, with all specimens completing 500 cycles and showing the least variability. In comparison, interference screw fixation had the lowest average load-to-failure (271 ± 71 N) with two failures occurring before 500 cycles, and the keyhole technique showed intermediate performance at 319 ± 45 N, also with two early failures. Cyclic displacement after 500 cycles was lowest for the interference screw (3.16 ± 0.52 mm), followed by the keyhole (11.51 ± 2.08 mm), and highest for the cortical button (13.84 ± 1.90 mm). Displacement range after 500 cycles was also lowest in the interference screw group (0.62 ± 0.05 mm), compared to the cortical button (0.88 ± 0.07 mm) and keyhole (0.91 ± 0.23 mm). DIC revealed the highest maximum first principal strain around cortical button fixation (0.21%), followed by interference screw (0.16%) and keyhole (0.13%). CONCLUSION: Cortical button fixation demonstrated the highest load-to-failure and the lowest variability, indicating mechanical reliability. The interference screw and keyhole techniques showed comparable load-to-failure values and cyclic displacement but exhibited greater variability. DIC analysis revealed higher localized strain around the cortical button fixation, whereas the interference screw and keyhole techniques displayed more evenly distributed strain. LEVEL OF EVIDENCE: Level V.

• Keywords
• biceps tenodesis, cortical button, digital image correlation, interference screw, keyhole technique, subpectoral tenodesis,
• Publication type
• Journal Article MeSH

BACKGROUND AND OBJECTIVE: The use of bone allograft reconstructions after tumor resection can introduce significant complications. Stable fixation is required to decrease the incidence of mechanical complications of segmental bone allografts. The purpose of the present study is to compare plating fixation methods of diaphyseal allografts after intercalary resection of the femur. METHODS: We created four defined fixation models using plates and/or intramedullary polymethylmethacrylate (PMMA) to simulate typical bone tumor resection with intercalary allograft reconstruction. One angularly stable plate (DFP) with 13 locking screws and fresh frozen allografts (labeled "I") were used for bone reconstruction. Three modified reconstructions were created: "II" included a supplementary plate (SP) with four locking screws, "III" was augmented with intramedullary PMMA in the allograft, and "IV" combined intramedullary PMMA and both plates. We applied a load model that simulates partial weight bearing on the lower limb to simulate the load during postoperative rehabilitation. RESULTS: The highest stress in the DFP occurred at the allograft-bone transition, with variant IV reaching 297 MPa. PMMA augmentation reduced median interfragmentary motion (IFM) and sliding distances, with variant III achieving the lowest distal sliding distance (0.9 μm) in the distal area. Supplementary plate fixation reduced maximal and median proximal IFM distances (86.9 μm in variant II vs. 116.0 μm in variant I) but increased sliding distances (23.7 μm in variant II vs. 0.6 μm in variant I). CONCLUSIONS: PMMA augmentation reduces IFM and sliding distances, enhancing rigidity, particularly in the distal area. Supplementary plate fixation decreases IFM distances in the proximal area but increases sliding distances in the same region. Variants III and IV demonstrate lower IFM and sliding distances in the distal area overall. Variant III shows very low sliding distances in both distal and proximal areas. Variant IV combines improved firmness with slightly higher stress levels.

• MeSH
• Allografts MeSH
• Biomechanical Phenomena MeSH
• Femur * surgery   MeSH
• Bone Plates * MeSH
• Bone Screws MeSH
• Humans MeSH
• Femoral Neoplasms * surgery   MeSH
• Bone Neoplasms * surgery   MeSH
• Computer Simulation * MeSH
• Polymethyl Methacrylate MeSH
• Bone Transplantation * methods   MeSH
• Plastic Surgery Procedures * methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Polymethyl Methacrylate MeSH