Nonarthritic Hip Pathology

Introduction

Due to the high loads received by the hip joint during walking and running, the hip and its surrounding structures are prone to numerous pathologies with varying degrees of severity. In a population of participants 65 years and older, near 20% had self-reported hip pain that consequently impacted their overall health such that without these symptoms, their average general health status would be similar to people under 65 years of age. Hip pathology is especially prominent in the athletic population due to the additional forces experienced by the hip during high-impact sports-related activities. According to a recent study by Kerbel et al. athletes participating in soccer, ice hockey, and running are among the most at risk for hip injuries and disorders that can occur as a result of acute trauma or overuse or as gradual onsets.

The more widely researched conditions, and much of our understanding of hip pathologies, are associated with intra-articular pathologies and arthritic disorders. There are, however, many abnormalities that contribute to significant hip pain, which exist outside these types of lesions. An important part of treating patients with hip pain is to consider the local and surrounding factors, including nervous, osteoligamentous, tendinous, and muscular structures. Properly diagnosing and understanding hip pathology can be difficult because of its complex nature and the tendency for conditions to be concomitant and symptoms to overlap, but it is crucial nonetheless. This chapter will focus on the recognition and management of extra-articular hip pathologies.

Structural and Functional Anatomy

The hip joint plays a key role in movement, stability in facilitating weight-bearing, and dynamic support for the body. It is composed of a system of interactions between the skeleton and the surrounding soft connective tissue. A ball-and-socket joint is formed by the articulation of the femoral head and the acetabulum, which is formed by the ischium, ilium, and pubis bones. The acetabulum encompasses the entire head of the femur allowing for movement along three major axes. For support, the hip labrum and a group of superficial and deep ligaments form a fibrous capsulolabral structure, which restricts translation at the femoroacetabular articulation while still allowing for complex rotation and planar movements. ^, The movements permitted by the hip are flexion, extension, adduction, abduction, external rotation, and internal rotation. Some of the major muscles that provide these movements include the iliopsoas (hip flexion), the hamstring muscles (extension), the adductor muscles (adduction), and the gluteus maximus (extension and external rotation), minimus (abduction and internal rotation), and medius (abduction) muscles. Overall, there are 22 muscles providing stability and the forces necessary for movement, which can be divided by their anatomic positioning or their actions.

Based on the pathways of nerves through the hip and thigh regions, most intra-articular pathologies elicit pain that radiates to the anterior and medial hip (i.e., groin), whereas extra-articular conditions typically cause pain rotating to the posterior and lateral aspect of the hip. However, intra-articular pathology can certainly cause posterior and/or laterally based hip pain, and clinicians must be aware of atypical sources of hip pain when evaluating patients, particularly females.

Key anatomic structures within and around the hip and groin area include several bursae, which are fluid-filled sacs that function to cushion the joint area. These bursae include the trochanteric bursa on the lateral side of the hip as well as the iliopsoas bursa, found in the anteromedial aspect of the hip and thigh. Inflammation of these sacs, called bursitis, can be caused by several different conditions and represents a common extra-articular pathology that is a source of hip pain. In addition, injuries to the thigh muscles that generate hip movement, including strains and tears, as well as lumbar spine conditions, can often be causes of the referred hip pain. Furthermore, stress fractures about the hip and dysfunction in the surrounding joints, such as the sacroiliac (SI) joint, are all among the various nonarthritic hip pathologies that lead to hip pain. ^, Table 10.1 provides a summary of the nonarthritic and extra-articular hip pathologies to be discussed in the subsequent sections of this chapter, which are organized by anatomic location.