Clinical Care of the Runner

Assessment, Biomechanical Principles, and Injury Management

Mark Harrast

• Publisher: Elsevier
• Year: 2019
• ISBN:
  9780323679503
• Topic: Medicine
• Subtopic: Orthopedics

Offering current guidance from national and international experts, Clinical Care of the Runner provides a comprehensive, practical approach to caring for the runner patient. Editor Dr. Mark A. Harrast, Clinical Professor of Rehabilitation Medicine and Sports Medicine and Medical Director for Husky Stadium and the Seattle Marathon, ensures that you're up to date with assessment, biomechanics, musculoskeletal injuries, medical illness, training, special populations, and other key topics.

• Covers general topics such as evaluation of the injured runner, on-the-field and in-office assessment, and sports psychology for the runner.
• Includes biomechanics and rehabilitation chapters, including running gait assessment, choosing a running shoe, and deep water running for prevention and rehabilitation of running injuries.
• Provides expert guidance on bone stress injuries and bone health, osteoarthritis and running, knee injuries in runners, and other musculoskeletal injuries.
• Features a section on specific populations such as the novice runner, the youth runner, the peripartum runner, and the ultramarathoner.
• Consolidates today's available information and guidance into a single, convenient resource.

Section III

Musculoskeletal Injuries

Outline

Chapter 14. Bone Stress Injuries

Chapter 15. Bone Health of the Runner: Metabolic Workup and Impact on Fracture Risk

Chapter 16. Osteoarthritis and Running

Chapter 17. Hip, Pelvis, and Thigh Injuries in Runners

Chapter 18. Knee Injuries in Runners

Chapter 19. Exertional Leg Pain in Runners

Chapter 20. Ankle and Foot Injuries in Runners

Chapter 14

Bone Stress Injuries

Megan Roche, MD, Michael Fredericson, MD, and Emily Kraus, MD

Abstract

Bone stress injuries (BSIs) occur when bone is no longer able to withstand repetitive, mechanical loading. BSIs are common in elite and recreational runners. The 1-year prospective incidence of BSI in competitive cross-country and track-and-field athletes is as high as 21%. Early identification and proper management of BSI may prevent progression of injury down the pathology continuum on magnetic resonance imaging. BSI may represent a systemic deficit in metabolic or hormonal status. Screening for the Female Athlete Triad and parallel male Triad can help prevent BSI or BSI recurrence. This chapter uses evidence-based medicine to highlight the pathophysiology, risk factors, clinical evaluation, and management of common BSIs in runners. Within this framework, BSIs are grouped by high-, moderate-, and low-risk anatomic sites based on healing properties. With evidence-based management and proper rehabilitation principles, most runners can return to play with conservative treatment.

Keywords

Bone stress injury; Bone stress injury runner; Stress fracture; Stress reaction; Triad

Introduction and Epidemiology

Bone stress injuries (BSIs) result when bone is unable to withstand repetitive, mechanical loading due to factors that disrupt bone load, bone strength, or bone remodeling. BSIs are a common concern in runners. Studies suggest that BSIs account for 0.7%–20% of all sports medicine clinic injuries. ¹

Competitive cross-country and track-and-field athletes have the highest incidence of BSIs compared with other athletes. ¹ The 1-year prospective incidence of BSI in competitive cross-country and track-and-field athletes ranges from 4.9% to 21.1%. ²

BSIs exist along a pathology continuum progressing from radiographic findings on magnetic resonance imaging (MRI) of periosteal edema with varying degrees of bone marrow edema, to more advanced injuries showing evidence of a cortical fracture line. ³ Early identification and proper management of BSIs may help prevent injuries from progressing along this pathology continuum.

BSI may represent a broader, systemic deficit in metabolic, hormonal, or nutritional status. Low energy availability results from insufficient caloric intake and/or excessive energy expenditure and can impact bone health. The terms Relative Energy Deficiency in Sport (RED-S), the Female Athlete Triad (Triad), and the parallel Triad in males all have energy availability as a key element. Proper screening for low-energy availability and other systemic deficits can help prevent BSI recurrence. The metabolic, hormonal, and nutritional aspects of BSI are covered more fully in Chapter 15, “Bone Health of the Runner: Metabolic Work-up and Impact on Fracture Risk,” in Clinical Care of the Runner.

This chapter reviews evidence-based medicine and rehabilitation principles for BSIs. Within this framework, the pathophysiology, risk factors, clinical evaluation, and management of BSIs are detailed, followed by a comprehensive discussion of BSI evaluation based on specific anatomic location.

Pathophysiology of Bone Stress Injuries

Trabecular, or cancellous, bone serves as the internal tissue of skeletal bone and is less dense and more elastic than cortical bone, which typically forms the outer casing of long bones. Cortical bone represents approximately 80% of bone mass and consists of the outer periosteum and inner endosteum. ⁴

Gonadal hormone irregularities can predispose athletes to cortical and trabecular BSI and/or osteopenia or osteoporosis. Athletes with nutritional deficiencies, hormonal irregularities, and lower bone mineral density (BMD) have an increased incidence of cortical and trabecular BSI compared with athletes without these attributes. ⁵

According to Wolff's law, external mechanical forces cause adaptive changes in the internal architecture of the trabeculae, followed by secondary adaptive changes in the external architecture of the cortical bone at the osteoids. ⁶ In cortical bone, the initial response to an increase in mechanical force is osteoclastic activity, leading to resorption of bone. Osteoblastic activity fills resorption cavities with lamellar bone, but formation of bone is slower than resorption of bone. In trabecular bone, external mechanical force may result in microdamage of the trabeculae, which is repaired by microcallus. If insufficient time is given to adapt to an external mechanical force, an imbalance can occur between bone remodeling and bone damage in both cortical and trabecular bones. ⁷

The resulting pathophysiology is currently debated, but accumulating microdamage may coalesce to progress down the BSI pathology spectrum. Stress reactions are associated with periosteal and/or bone marrow edema, and stress fractures have a discernible fracture line. ⁴

Bone exhibits anisotropic mechanical behavior or varying strength as a function of direction of load applied. Tensile loading causes elongation and narrowing of a structure, whereas compressive loading causes shortening and widening of a structure. The mechanical properties of bone enable bone to be stronger in compression than in tension. ⁸ Due to intrinsic stability of the fracture pattern and direct osteogenesis, compression stress fractures are more likely to heal with conservative measures compared with tension stress fractures. ⁶

Risk Factors for Bone Stress Injury

Identification and modification of r...