Study Design. An experimental laboratory-based biomechanical study. Objective. To investigate the correlation between cage size and subsidence and to quantify the resistance to subsidence that a larger cage can provide. Summary of Background Data. The assumption that a bigger interbody cage confers less subsidence has not been proven. There was no previous study that has shown the superiority of lateral cages to bullet cages in terms of subsidence and none that has quantified the correlation between cage size and subsidence. Methods. A cage was compressed between two standardized polyurethane foam blocks at a constant speed. Four sizes of bullet cages used for transforaminal lumbar interbody fusion (TLIF) and six sizes of lateral cages used for lateral lumbar interbody fusion (LLIF) were tested. The force required for a 5 mm subsidence, axial area of cages, and stiffness were analyzed. Results. A larger cage required a significantly higher force for a 5 mm subsidence. Longer bullet cages required marginal force increments of only 6.2% to 14.6% compared to the smallest bullet cage. Lateral cages, however, required substantially higher increments of force, ranging from 136.4% to 235.7%. The average force of lateral cages was three times that of bullet cages (6426.5 vs. 2115.9 N), and the average stiffness of the LLIF constructs was 3.6 times that of the TLIF constructs (635.5 vs. 2284.2 N/mm). There was a strong correlation between the axial area of cages and the force for a 5 mm subsidence. Every 1 mm2 increment of axial area corresponded to approximately 8 N increment of force. Conclusion. Cage size correlated strongly with the force required for a 5 mm subsidence. The LLIF constructs required higher force and were stiffer than the TLIF constructs. Among bullet cages, longer cages only required marginal increments of force. Lateral cages, however, required substantially higher force. Level of Evidence: N/A

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Introduction This study aimed to reveal the entire cutaneous nerve distribution pattern of the leg and provide a morphological basis for sensory reconstruction during skin flap transplantation. Materials and Methods Twelve adult cadavers were fixed with formalin, and the whole leg skin with subcutaneous fat was removed close to the muscle surface. The cutaneous nerves were visualized using modified Sihler's staining to reveal the distribution and innervation density of the cutaneous nerves. Results The saphenous nerve innervated the anterior part, 82.2% of the upper‐middle region of the lateral part of the anterolateral leg, and the upper 63.4% of the medial posterior leg. The superficial peroneal nerve innervated 90.1% of the lateral lower one‐third of the anterolateral leg. The medial sural cutaneous nerve covered 26.4% of the posterior leg. The lateral sural cutaneous nerve covered 42.3% (approximately 28.6% overlap with the saphenous nerve) of the upper‐middle region of the anterolateral and posterolateral leg. The number of branches differed between certain cutaneous nerves in the leg. Communications were observed between the arborizations of the four cutaneous nerves mentioned above. The highest density of primary and secondary nerve branches was observed in the upper one‐third of the lateral posterior leg. The upper one‐third of the posteromedial leg contained the highest density of intracutaneous nerve branches and highest number of total nerve branches. Conclusions These results may be used to map sensory regions when designing leg skin flaps for reconstruction surgery to obtain improved sensory recovery.

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