Bony prominences are areas where bone lies close to the skin surface, with minimal protective layers of fat or muscle tissue. They bear a disproportionate amount of pressure when a person is seated or lying down for extended periods. Standard medical practice is to avoid direct massage on these areas, particularly for individuals with limited mobility who are at risk for skin breakdown. Applying mechanical force directly to these vulnerable spots can significantly increase the risk of serious underlying tissue injury and subsequent pressure ulcer formation.
Identifying Areas of High Vulnerability
High-risk anatomical locations are found where the body’s weight is concentrated against an external surface. The most common site for pressure injury is the sacrum, the large triangular bone at the base of the spine, and the coccyx, or tailbone. These areas are vulnerable because they sustain significant force when a person is lying flat or sitting up in bed.
The heels are also extremely susceptible because the underlying calcaneus bone is covered by a comparatively thin layer of soft tissue. Other vulnerable sites include the bony points of the hips, known as the greater trochanters, which are strained when lying on one side. Furthermore, the elbows and the scapulae, or shoulder blades, represent sites where the skin is easily compressed between the bone and a supportive surface.
The Mechanism of Tissue Damage
Directly massaging a bony prominence can initiate or accelerate a deep tissue injury (DTI), a form of pressure-induced damage that begins in the deeper layers of muscle and subcutaneous fat. Muscle and fat tissues are less tolerant of reduced blood flow than the skin, meaning injury can start near the bone and progress outward toward the surface. This damage often appears as a persistent, non-blanchable deep red or purple area on intact skin.
A major factor contributing to this damage is the mechanical stress caused by friction and shearing forces. Friction is the resistance created when the skin is dragged across a surface, while shearing occurs when the skin remains stationary but the underlying tissue shifts. The act of vigorous massage itself introduces these shearing forces, stretching blood vessels and compromising capillary blood flow, which leads to localized ischemia, or oxygen deprivation. Without a continuous supply of oxygen and nutrients, the cells begin to die, leading to tissue necrosis.
Safe Alternatives for Pressure Management
Managing pressure and maintaining tissue health requires a focus on safe, preventative strategies. A fundamental strategy is implementing a systematic repositioning schedule to redistribute sustained pressure away from vulnerable areas. While a two-hour turning schedule is a common standard in many care settings, the frequency should be tailored to the individual’s tolerance for pressure and overall condition.
Specialized support surfaces are essential tools for pressure redistribution:
- Higher-specification foam mattresses or alternating-pressure systems for bed-bound individuals.
- Pressure-redistributing cushions for those who can sit, protecting the ischial tuberosities.
- Prophylactic dressings, such as soft silicone multi-layered foam, placed over high-risk areas like the sacrum and heels to provide cushioning and reduce friction.
Maintaining the resilience of the skin and underlying tissue also depends on comprehensive care, including attention to nutrition and hydration. Ensuring adequate intake of protein and calories is necessary to support tissue repair and overall skin integrity. Caregivers should focus on gentle cleaning and moisturizing of the skin around the prominence, keeping the skin clean and dry while avoiding any force that could cause friction or shear over the bone itself.