PubMed^® Literature Review

Biomechanics concerning plate-stem overlap aims to ensure stability and prevent stress risers that could lead to implant failure or refracture [1-3]. The biomechanical study by Walcher et al. (2016) utilized composite femurs with cemented hip stems and applied distal femoral plates at varying distances from the stem tip [1]. Their findings indicated that strain on the bone increased with decreasing overlap or gap between plate and stem, suggesting that closer proximity may predispose to higher stress concentrations. They recommended at least 6 cm of minimal gap or overlap in osteoporotic bone models to avoid creating stress risers. Kempthorne et al. (2018) examined different configurations using composite bones fitted with cemented stems overlapped by lateral plates [2]. Their results also emphasized lower strain levels when there was sufficient proximal extension of the plate past the tip of the stem—specifically two shaft diameters—which corresponds roughly to approximately 6 cm depending on bone size. Constructs without overlap or those with small gaps demonstrated significantly higher strains leading to lower forces required for fracture under torsional and lateral bending loads. Similarly, Kubiak et al. (2015) analyzed cortical strain and load-to-failure relationships between locked compression plating constructs overlapping cemented stems [3]. Their data showed reduced cortical strain as constructs transitioned from an 8 cm gap between plate end and stem tip towards overlapped configurations, corroborating earlier findings regarding optimal construct length for mitigating stress concentration effects. Collectively, these studies suggest that there is an optimal zone where plate fixation should either sufficiently overlap or be spaced away from a pre-existing femoral stem within certain limits—too close may create high stresses while too far might not provide adequate support against loading forces experienced during normal activities or falls post-surgery. In summary, based upon current biomechanical evidence available through these analyses: - There appears to be consensus recommending an approximate distance of at least two shaft diameters—or around 6 cm—as being beneficial for reducing inter-prosthetic strain. - Overlapping constructs have shown reduced cortical strains compared with non-overlapping ones. - A minimum safe distance should be maintained between plate end and prosthesis tip to minimize risk factors associated with subsequent fractures due to elevated local stresses. These conclusions serve as guidelines derived from simulated conditions which must be carefully interpreted within clinical context considering patient-specific factors such as bone quality, activity level, weight-bearing status among others before translating into surgical practice decisions.