A Novel Hip Pad Design to Prevent Meralgia Paresthetica After Surgery in the Prone Position

Many posterior spine and cranial procedures require patients to lie in the prone position for extended periods. Industry-standard operating table designs support the patient with two adjacent, rectangular hip pads that are positioned near the anterior superior iliac spine. As a result, meralgia paresthetica (MP) can occur from prolonged impingement of the lateral femoral cutaneous nerve (LFCN), leading to paresthesias, sensory loss, and pain in the anterolateral thigh. MP occurs postoperatively in about 24% of posterior spine cases lasting longer than 3.5 h (Agarwal et al. in Clin Spine Surg 31:53, 2018). Currently, there are no hip pads in the market designed to protect the LFCN during these procedures. This study aimed to develop a hip pad that protects the LFCN from compression without causing additional risk to the patient. Multiple prototypes with alternative geometries to the industry-standard rectangular hip pad were designed based on efficacy, compatibility with current surgical tables, ease of fabrication, and cost of production. To assess design efficacy, two rounds of flow rate testing were conducted using hollow rubber tubing to simulate the LFCN. The tube was placed over each hip pad prototype and water flow rates were measured with increasing weights applied. After the initial round of testing, a more anatomically representative testing apparatus was constructed to simulate the biomechanics of the inguinal region and a second round of flow rate testing was performed. The data was analyzed using one-way ANOVA tests for statistically significant differences in flow rates and cross-referenced between both rounds of testing. The U-shaped pad design demonstrated a significantly better flow rate when compared to industry-standard hip pad geometries. Improved flow rate testing found a significant difference between the Control and U-shaped design flow rates at 0 kg (p = 0.0216 < 0.05) and at 11.5 kg (p = 0.0036 < 0.05) of compression weight. The results provide promising evidence that the prototype designs may reduce compression on the LCFN when compared to industry standard designs. Based on preliminary data, it appears the U-shaped design is the best prototype to prevent pressure on the LFCN. Further testing iterations are needed to support the efficacy of the prototype hip pad designs.