Lower Back Contusion

Anatomy

The back gets its shape from the vertebral column, which includes the cervical spine of the neck, the thoracic spine of the chest, and the lumbar spine of the lower back. The lower back includes the lumbar vertebrae and sacrum. The smaller motion muscles of the back include the multifidi, which span only a couple of segments, and the larger muscles that span the entire circumference of the lower abdomen and back. Finally, there are the larger groups that connect the upper trunk and lower trunk, such as the latissmus dorsi and gluteus maximus.

Physiologic Response

Muscle tissue injury recovers by a process of repair. It does so in three distinct phases. The first phase is the destructive phase. There is acute rupture followed by necrosis of the muscle cells. This also involves variable collection of blood called a hematoma. Inflammatory cells also participate in this phase. The second phase is the repair phase, when the muscle cells are regenerated and there is connective tissue scar formation. The concern here is contracture with extensive scar. The third phase is the remodeling phase, in which the new muscle cells mature and the scar tissue remodels.

Common bruising is a minor contusion with capillary leakage of red blood cells. Most often, [Page 814]bruising is indeed minor and disappears in 2 to 4 weeks. However, certain individuals are more prone to bruising, such as women, children, elderly people, those taking blood thinners, and individuals with genetic bleeding disorders. Severe contusions may lead to pain and impaired movement due to scar tissue formation. Large hematomas may further limit motion and enhance scar formation. Rarely, a contusion with hematoma may stimulate bone formation in the muscle, called heterotopic bone formation. This latter entity is most common in the thigh and the elbow.

Clinical Presentation and Evaluation

Athletes will present with a history of a direct-impact injury. They will manifest localized pain, tenderness, and swelling. Discoloration may occur, with typical bruising progressing through four phases. Initially, it is bluish-red, followed by reddish-blue. It then turns to greenish-yellow and, finally, brown. These represent the breakdown phases of blood cells. Most significantly, the athlete will present with decreased movement. It is important to rule out an underlying, more significant injury. This would include spinal fracture and abdominal injuries such as a kidney laceration. An X-ray or bone scan should be considered to definitively rule out fractures. Fractures will usually manifest with tenderness to direct spinal palpation. If there is a question, a plain radiograph will help distinguish a fracture. Further imaging is often not needed. Magnetic resonance imaging (MRI) may aid in ruling out muscle tearing, but its expense often does not justify its use. A simple ultrasound image is an effective tool with minimal expense in the detection of hematoma and muscle disruption.

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