Articular cartilage, the resilient durable tissue that forms the opposing articulating surfaces of synovial joints, provides these surfaces with the low friction, lubrication, and wear characteristics that make possible smooth painless movement.1 It also absorbs mechanical load and spreads these applied loads onto subchondral bone.2 No synthetic or reparative material performs as well as a natural joint surface. Injuries or diseases of articular cartilage cause pain and loss of mobility for more people than disorders of any other musculoskeletal tissue. This chapter reviews current understanding of how the unique structure and composition of articular cartilage give the tissue its remarkable...
Bone is living, dynamic tissue that affects three main functions of the body: skeletal homeostasis (providing structure to house the internal organs as well as a system of pulleys and levers to move the body), mineral homeostasis (storing and releasing ions), and hematopoiesis (accommodating the machinery of blood cell formation). As living tissue, bone is in a state of continuous flux and renewal; osteoclastsresorb bone, and osteoblasts create new bone. This process allows ions to be released and stored. It also repairs areas of structural damage. Most bone forms according to the cartilage model, a process called endochondral ossification. The...
Articular cartilage, the resilient durable tissue that forms the opposing articulating surfaces of synovial joints, provides these surfaces with the low friction, lubrication, and wear characteristics that make possible smooth painless movement.1 It also absorbs mechanical load and spreads these applied loads onto subchondral bone.2 No synthetic or reparative material performs as well as a natural joint surface. Injuries or diseases of articular cartilage cause pain and loss of mobility for more people than disorders of any other musculoskeletal tissue. This chapter reviews current understanding of how the unique structure and composition of articular cartilage give the tissue its remarkable...
Synovial tissue is found in joints, tendon sheaths, and bursae and allows smooth motion. Synovial tissue is organized in a membranous structure called the synovium. This chapter describes the gross anatomy, histology, and function of synovium, on which the joints, tendons, and bursae depend for motion and metabolism. Synovial fluid, which is produced by the synovium and functions as the conduit for the synovium’s complex role, will also be discussed. Both inflammatory and noninflammatory conditions affect the synovium. The discussion of normal synovium and synovial fluid will lay the groundwork for understanding these conditions as well as synovial fluid collections,...
Skeletal ligaments are highly organized, fibrous tissues that connect bone to bone. Some ligaments are large and easily seen or felt; others are small and subtle. All share the task of protecting the joints from instability and allowing normal motion to occur with minimal resistance. The orientation of a ligament relative to the plane of the joint it crosses determines its mechanical function. For example, the anterior talofibular ligament, the structure most commonly injured in an ankle sprain, attaches the distal fibula to the lateral side of the talus, sloping somewhat anteriorly as it courses toward its distal attachment. Thus,...
Once thought to be vestigial and functionless, the menisci are now believed to play a critical role in knee biomechanics. The meniscus cushions the proximal tibia from impact, distributes the load of weight bearing over an area of maximal size, helps stabilize the joint against anterior displacement, helps lubricate the joint, and assists with proprioception (Fig. 1). Figure 1 The medial compartment of the knee showing the articulation of the menisci (M) with the condyles of the femur (F) and tibia (T). As shown, the meniscus increases contact between the bones and therefore distributes stress. (Reproduced with permission from Warren...
Skeletal muscle is the single largest tissue mass in the body, constituting 40% to 45% of the dry body weight. Muscles attach to the bones and produce movements or exert static forces. They can be connected directly to bone or insert on a bone by means of a tendon, which is a specialized type of connective tissue. The area of interface between a skeletal muscle and its tendon is called the musculotendinous junction. Skeletal muscles may take a variety of forms, from the slender sartorius to the broad, fan-shaped pectoralis major. However, their histologic architecture remains the same. Each muscle...
Inflammation is characterized by erythema, warmth, pain, and edema. Acute inflammation generally occurs in response to an injury or introduction of foreign material at a specific site and is an important part of wound healing. Chronic inflammation is usually associated with a systemic disease process, such as rheumatoid arthritis (RA), and itself can be a major source of disability. When inflammation affects the joints of the musculoskeletal system, it most often affects the synovial membrane,resulting ina condition calledsynovitis. Inflammation may also affect tendons or tendon sheaths (tendinitis); it also can occur extra-articularly in bursae (bursitis). While acute inflammation is often...
Shoulder and Arm Bones and Joints The shoulder comprises three bones (the clavicle, scapula, and humerus) and three joints (the glenohumeral, the acromioclavicular [AC], and the scapulothoracic) (Fig. 1). Figure 1 The bones of the shoulder: the clavicle, humerus, and scapula. The clavicle articulates with the scapula at the acromioclavicular joint. The humerus articulates with the scapula at the glenohumeral joint. The glenohumeral joint is the primary articulation of the shoulder, the point where the head of the humerus meets the glenoid. The AC and scapulothoracic joints attach the trunk to the scapula, with the arm appended to it. The...
Osteoarthritis is a family of degenerative joint diseases characterized by chronic pain, deformity, and progressive physical and psychological disability. Osteoarthritis without an identified cause is called primary osteoarthritis. Secondary osteoarthritis results from known precipitants such as bone ischemia, trauma, and neuropathy, among others. The common terminal state for all forms of osteoarthritis is the destruction of the joint. The diagnosis is made when a patient reports joint pain; radiographs demonstrate cartilage loss, hardening of the bone below the cartilage, and bone spur formation; and no other disease is responsible. It is essential to remember that not all patients with radiographic...
