Residency · Residency · Orthopedic Surgery
Sports-Related Fractures and Stress Injuries
Introduction
Stress injuries represent a spectrum of overuse bone pathology ranging from periosteal stress reactions to complete stress fractures. They account for up to 20% of all sports medicine clinic visits. Understanding the biomechanics, risk factors, high-risk versus low-risk locations, and management principles is essential for the orthopedic surgeon treating athletes.
Pathophysiology
According to Wolff's law, bone remodels in response to mechanical loads placed upon it. Stress injuries result from an imbalance between bone resorption and formation during the remodeling cycle. Repetitive submaximal loading leads to microdamage accumulation when remodeling cannot keep pace. The injury exists on a spectrum from stress reaction (periosteal edema, endosteal edema) to stress fracture (cortical fracture line). Bone fatigue failure can occur in normal bone subjected to abnormal stress (fatigue fracture) or in abnormal bone subjected to normal stress (insufficiency fracture).
Risk Factors
Extrinsic Factors
Extrinsic risk factors include rapid increases in training intensity, duration, or frequency ("too much, too soon"), changes in playing surface or footwear, inadequate recovery time between training sessions, and equipment factors such as worn shoes or hard surfaces.
Intrinsic Factors
Intrinsic risk factors include the female athlete triad or RED-S (disordered eating, menstrual dysfunction, and low bone mineral density), low vitamin D levels and calcium deficiency, lower extremity malalignment (pes planus, leg length discrepancy, excessive tibial torsion), prior history of stress fracture (which increases risk 2 to 6 times), low BMI, smoking, and poor conditioning.
Clinical Evaluation
The history reveals an insidious onset of activity-related pain that initially resolves with rest but progresses to pain at rest. Examination shows focal bony tenderness, and there may be localized swelling or periosteal thickening. The hop test and fulcrum test (for femoral shaft) can reproduce symptoms. Underlying metabolic or hormonal abnormalities should always be assessed, especially in female athletes.
Imaging
Radiographs are the initial study but may be negative for 2 to 6 weeks; findings to look for include periosteal reaction, cortical lucency, sclerosis, or callus formation. MRI is the gold standard with sensitivity approaching 100%. The Fredericson classification for tibial stress injuries grades severity: Grade 1 shows periosteal edema only, Grade 2 shows periosteal and marrow edema on T2, Grade 3 shows marrow edema on T1 and T2, and Grade 4 shows a visible fracture line. Bone scan is highly sensitive but less specific and is useful when MRI is contraindicated. CT is helpful for cortical detail, especially in the tarsal navicular and fifth metatarsal.
Classification: High-Risk vs. Low-Risk
Low-Risk Stress Fractures (Compression Side)
Low-risk locations include the posteromedial tibial shaft (the most common stress fracture overall), metatarsal shafts (second and third most common), calcaneus, fibula, and femoral shaft. These generally heal well with activity modification because they have good blood supply and are subjected to compression loading. Return to sport typically occurs within 4 to 8 weeks.
High-Risk Stress Fractures (Tension Side)
| Location | Risk Factor | Concern | Treatment |
|---|---|---|---|
| Femoral neck (tension/superolateral side) | Runners; military | Displacement → AVN | Percutaneous screw fixation |
| Anterior tibial cortex | Jumping athletes | "Dreaded black line"; nonunion | IM nailing or anterior tension band plate |
| Tarsal navicular (central 1/3) | Sprinters; jumpers | Watershed zone; nonunion | NWB cast 6-8 wks or screw fixation |
| 5th metatarsal (Jones zone) | Basketball; soccer | Poor vascularity; nonunion | Intramedullary screw fixation in athletes |
| Medial malleolus | Runners | Nonunion risk | Screw fixation if displaced/non-healing |
High-risk locations include the femoral neck (superolateral or tension side, with risk of displacement and AVN), the anterior tibial cortex (tension side, characterized by the dreaded black line and risk of nonunion), the tarsal navicular (central one-third watershed area, prone to nonunion), the fifth metatarsal (proximal diaphysis or Jones fracture zone, with poor vascularity), and the medial malleolus, great toe sesamoids, and patella. These require aggressive management, often surgical intervention, and carry risks of progression, nonunion, or catastrophic failure.
Management
Nonoperative Treatment (Low-Risk Fractures)
Relative rest with avoidance of impact activities is the foundation, while fitness is maintained through cross-training (cycling, swimming, deep water running). A progressive return to impact loading begins once the athlete is pain-free for 10 to 14 days. Modifiable risk factors should be corrected, including nutrition, vitamin D and calcium supplementation, training errors, and biomechanics. RED-S should be addressed with a multidisciplinary approach involving sports medicine, nutrition, psychology, and endocrinology.
Operative Treatment (High-Risk Fractures)
Femoral neck stress fractures on the tension side are treated with percutaneous screw fixation to prevent displacement. Anterior tibial cortex stress fractures are managed with intramedullary nailing for refractory cases, with anterior tension band plating as an alternative. Tarsal navicular fractures are treated with non-weight-bearing casting for 6 to 8 weeks if nondisplaced, or percutaneous screw fixation for displaced or recalcitrant cases. Fifth metatarsal (Jones fracture) stress fractures are treated with intramedullary screw fixation in athletes for faster return to sport. Medial malleolus stress fractures are treated with screw fixation if displaced or non-healing.
Specific Sport-Related Acute Fractures
Avulsion Fractures in Adolescent Athletes
Anterior superior iliac spine avulsions result from sartorius pull. Anterior inferior iliac spine avulsions result from rectus femoris pull. Ischial tuberosity avulsions result from hamstring pull. Most are treated nonoperatively, with surgical fixation reserved for displacement exceeding 2 cm.
Other Common Sport-Related Fractures
Clavicle fractures are the most common fracture in contact sports, with midshaft being the most common location. Operative fixation is considered for displaced, shortened, or comminuted fractures in athletes. Scaphoid fractures result from a fall on an outstretched hand and present with snuffbox tenderness; a high index of suspicion is needed. Mallet finger involves a distal phalanx avulsion with an extensor lag at the DIP joint and is treated with splinting in extension for 6 to 8 weeks.
Prevention
Prevention strategies include gradual training progression (the 10% rule for weekly mileage increases), adequate calcium (1000 to 1300 mg per day) and vitamin D (600 to 1000 IU per day) intake, appropriate footwear and training surfaces, screening for and addressing RED-S components, and biomechanical assessment and correction of lower extremity malalignment.
Clinical Pearls
MRI is the gold standard for diagnosis, as radiographs may be negative for weeks. Distinguishing high-risk (tension side, poor vascularity) from low-risk (compression side) stress fractures is essential because management differs dramatically. The female athlete triad and RED-S must be screened for in all athletes with stress fractures, especially those with recurrent injuries. High-risk stress fractures often require surgical intervention to prevent catastrophic failure or nonunion. Prevention focuses on training load management, nutrition optimization, and biomechanical correction.
References
- Fredericson M, Jennings F, Beaulieu C, Matheson GO. "Stress Fractures in Athletes." Topics in Magnetic Resonance Imaging. 2006;17(5):309-325.
- Nattiv A, Kennedy G, Barrack MT, et al. "Correlation of MRI Grading of Bone Stress Injuries with Clinical Risk Factors and Return to Play." American Journal of Sports Medicine. 2013;41(8):1930-1941.
- Tenforde AS, Kraus E, Fredericson M. "Bone Stress Injuries in Runners." Physical Medicine and Rehabilitation Clinics. 2016;27(1):139-149.
- Boden BP, Osbahr DC. "High-Risk Stress Fractures: Evaluation and Treatment." Journal of the American Academy of Orthopaedic Surgeons. 2000;8(6):344-353.