Why does the site of an old fracture become painful when exposed to warm water?

From the Guidelines

Pain at the site of an old fracture during warm showers is typically due to changes in blood flow and pressure in the healed bone area, and managing this discomfort may involve gradually adjusting water temperature and taking over-the-counter pain relievers like acetaminophen or ibuprofen before showering. When exposed to warm water, blood vessels dilate, increasing blood flow to the previously injured area, which can cause pressure on surrounding nerves and tissues that may have been sensitized during the healing process 1. The pain is often more noticeable in fractures that healed with some irregularity or developed post-traumatic arthritis. To manage this discomfort, the following strategies can be considered:

• Gradually adjusting water temperature rather than immediately using hot water
• Taking over-the-counter pain relievers like acetaminophen (500-1000mg) or ibuprofen (200-400mg) about 30 minutes before showering if the pain is predictable, as recommended for managing acute trauma pain in the elderly in a multimodal analgesic approach 1
• Considering brief cold compresses after showering to reduce inflammation If the pain persists or worsens, it is essential to consult a healthcare provider as it could indicate incomplete healing, developing arthritis, or other complications that might require further evaluation with imaging studies or specialized treatment. In elderly patients, a regular administration of intravenous acetaminophen every 6 hours as first-line treatment in managing acute trauma pain is recommended, and considering adding NSAIDs in patients presenting with severe pain, taking into account potential adverse events and pharmacological interactions 1. Additionally, the implementation of a Multi-Modal-Analgesia approach, including acetaminophen, gabapentinoids, NSAIDs, lidocaine patches, and opioids only for breakthrough pain, can be beneficial in managing pain in elderly patients with trauma 1.

From the Research

Possible Causes of Pain at the Site of an Old Fracture

• Pain at the site of an old fracture can be caused by various factors, including delayed union, malunion, or nonunion of the fracture 2
• These complications can lead to substantial suffering and economic burden, making early intervention necessary
• The treatment of malunion, which is a consolidation of a fracture in a position of deformity and malalignment, is a lengthy and complex process aimed at relieving pain, restoring alignment, and function 2

Effect of Warm Water on the Site of an Old Fracture

• There is no direct evidence to explain why warm water would cause pain at the site of an old fracture
• However, it is possible that the warm water may cause increased blood flow to the area, leading to inflammation and pain in cases where the fracture has not fully healed or has resulted in malunion or nonunion 2

Management of Pain Associated with Fractures

• The management of pain associated with fractures is complex and multifactorial, requiring nuanced clinical judgment 3
• Multimodal pain control, including the use of non-steroidal anti-inflammatory drugs (NSAIDs), may be effective in reducing pain and the need for opioids after traumatic fracture 4
• However, the use of NSAIDs may have a small effect on non-union, and further research is needed to fully understand the risks and benefits of their use in fracture management 4