Stress Reaction and Fractures

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Overview of Stress Reactions and Fractures

Stress injuries range from periostitis—an inflammatory reaction of the periosteum—to a complete stress fracture involving a full cortical break (see Image. Stress Reaction). These injuries result from repetitive submaximal loading of bone over time and were first documented in the mid-19th century among military recruits, described as “March Fractures” (see Image. March Fracture of Second Metatarsal). Julius Wolff’s theory (1836–1902) holds that bones remodel in response to mechanical loads. When repetitive loading surpasses the bone’s adaptive capacity, osteoclast activity outpaces osteoblasts, leading to progressive microdamage and, ultimately, a stress fracture.

Patients typically notice symptom onset 2 to 3 weeks after an increase in training volume or intensity, with pain that initially occurs after activity and later persists at rest. Stress injuries occur most commonly in the lower extremities (eg, tibia, femur, metatarsals) and are seen frequently in running and jumping sports. Upper extremity stress injuries (eg, ulnar fractures) are less common but occur in specific populations. Diagnosis requires a high index of suspicion, a detailed history, physical examination, and imaging. Plain radiographs may remain normal for 2 to 4 weeks; thus, advanced imaging such as magnetic resonance imaging (MRI) is often necessary. Most stress fractures respond to conservative management, but high-risk fractures (eg, tension-sided femoral neck or anterior tibial cortex) may require surgical intervention. Early recognition and preventive strategies (eg, gradual increases in training) remain critical to avoiding complications.

Lower Extremity Stress Fractures

The following conditions are various types of injuries affecting lower extremity bones:

Tibia

The tibia is the most frequently affected site of stress reactions and fractures.

1. Medial tibial stress syndrome (MTSS): Also known as shin splints, MTSS can be difficult to distinguish from medial tibial stress fractures. MTSS pain worsens with exertion, whereas stress fracture pain often persists even during daily activities.

2. Anterior cortex tibial stress fractures: These are less common and affect jumping or leaping athletes. They may present radiographically as a “dreaded black line” and carry a high risk of nonunion. Aggressive conservative measures or surgical fixation with intramedullary rods or flexible plates may be necessary.

3. Medial tibial plateau stress fractures: These are rare, often mistaken for meniscal injuries or pes anserine bursitis, and require a high index of suspicion.

Femur

1. Femoral neck stress fractures: These constitute approximately 11% of stress injuries in athletes and predominantly affect runners. Two subtypes exist:

   1. Tension-type (distraction) fractures: Involve the superior-lateral femoral neck and present the highest risk for complete fracture. Early detection is paramount.

   2. Compression-type fractures: Involve the inferior-medial femoral neck and occur more often in younger athletes. If no fracture line is visible, nonsurgical management may suffice.

2. Femoral shaft stress fractures: These account for 22.5% of stress fractures in military recruits. Patients report vague, insidious leg pain. The “fulcrum test” may help localize pain. Nondisplaced lesions often respond well to conservative care.

Fibula

Fibular stress fractures usually occur in the distal third of the fibula, proximal to the tibiofibular ligament. Pain is reproducible on palpation.

Patella

Rare patellar stress fractures can be transverse or vertical. Transverse fractures carry a greater risk of displacement, often requiring immobilization or surgical fixation.

Medial Malleolus

Vertical stress fractures at the junction of the medial malleolus and tibial plafond appear in running and jumping athletes. Full cortical disruption usually necessitates surgical intervention.

Pelvis

Pelvic stress fractures can present vaguely, often mimicking adductor strains, osteitis pubis, or sacroiliitis. Common sites include the ischiopubic ramus and sacrum, especially in runners.

Foot and Ankle

1. Calcaneus: Patients show tenderness posterior to the talus and a positive squeeze test.

2. Navicular: Common in runners and basketball players, these fractures carry a high risk of nonunion due to poor blood supply. Tenderness over the navicular is a key clinical clue.

3. Metatarsals: Represent about 9% of stress fractures in athletes, usually occurring in the second or third metatarsal. Swelling, point tenderness, and pain exacerbated by weight-bearing are typical. A “dancer’s fracture” occurs at the base of the second metatarsal, while fractures distal to the tuberosity of the fifth metatarsal are called “Jones fractures.”

4. Sesamoids: Stress fractures of the great toe sesamoids present with gradual unilateral plantar pain, commonly affecting the medial sesamoid (see Image. Sesamoid Stress Fracture).

Upper Extremity and Rib Stress Fractures

Upper extremity stress fractures are uncommon and most often occur in the ulna. Rib stress fractures, though rare, can be seen in specific groups:

1. First rib: Seen in pitchers, basketball players, weightlifters, and ballet dancers.

2. Ribs 4 to 9: Common in competitive rowers; posteromedial fractures can occur in golfers.