Why is Intramedullary (IM) nail insertion more painful than hemiarthroplasty?

From the Guidelines

Intramedullary (IM) nail fixation is more painful than hemiarthroplasty due to the differences in surgical approach and bone manipulation, with IM nailing causing significant periosteal irritation and inflammatory responses. The process of reaming the medullary canal of the bone during IM nailing stimulates intraosseous nerve endings, triggering intense inflammatory responses and activating nociceptors throughout the bone 1. Additionally, IM nailing often requires more forceful manipulation during insertion, creating microfractures and tissue trauma. The nail itself exerts pressure against the endosteal surface during weight-bearing, causing ongoing mechanical pain.

In contrast, hemiarthroplasty involves removing the damaged femoral head and replacing it with a prosthesis, which eliminates the pain source rather than stabilizing it. Hemiarthroplasty also typically involves less intramedullary reaming and manipulation of the intact bone. According to a study published in 2013, operative intervention for metastatic fractures of long bones provides a good functional result in approximately 80% to 85% of patients, and a good analgesic effect is accomplished in the majority of patients 1.

For pain management following IM nailing, a multimodal approach is recommended, including:

• Scheduled acetaminophen (1000mg every 6 hours)
• NSAIDs like celecoxib (200mg twice daily)
• Short-term opioids such as oxycodone (5-10mg every 4-6 hours as needed) for breakthrough pain
• Early mobilization and physical therapy. It is essential to note that post-operative radiotherapy is commonly recommended regardless of the surgical procedure for bony metastases, and the typical schedule is 30 Gy in 10 fractions, although The British Association of Surgical Oncologists guidelines recommends 20 Gy in 5 fractions 1.

From the Research

Comparison of IM Nail and Hemiarthroplasty

• IM nail and hemiarthroplasty are two different surgical procedures used to treat fractures, with IM nail being used for long-bone fracture fixation and hemiarthroplasty being used for malignant hip lesions.
• A study published in 2017 2 found that hemiarthroplasty was associated with lower risk of pathologic fracture, fixation failure, or reoperation compared to IM nail fixation.

Pain Associated with IM Nail

• Insertion-related pain is a common complication of IM nail fixation, with proposed theories including hardware prominence, suboptimal nail entry points, and local heterotrophic ossification 3.
• A study published in 2020 4 found that anterior knee pain was the most frequent complication of IM nail fixation for tibial shaft fractures, occurring in 23% of patients.
• The study also found that 18% of patients required at least one subsequent surgery, with screw removal due to pain or discomfort being the most frequent indication.

Blood Loss and Transfusion Risk

• Blood loss can be a result of the original trauma or secondary to the subsequent surgical insult, especially during the reaming of the intramedullary canal 5.
• A study published in 2023 5 found that 62.7% of patients required blood transfusion post-operatively, with pre-operative Hb <100 g/L, nail/canal ratio <70%, and need for open reduction being associated with an increased risk of transfusion.

Reasons for Increased Pain in IM Nail

• The increased pain associated with IM nail compared to hemiarthroplasty may be due to the insertion-related pain and complications associated with IM nail fixation, such as hardware prominence and suboptimal nail entry points 3, 4.
• Additionally, the blood loss and transfusion risk associated with IM nail fixation may also contribute to the increased pain and discomfort experienced by patients 5.