Surgical Treatment of Joint Diseases

Epidemiology

Estimates of the prevalence of arthritis and other rheumatic diseases demonstrate the enormous impact that these conditions have on the U.S. populace and the health care system in general. Over 21% of U.S. adults report physician-diagnosed arthritis. Osteoarthritis ( Chapter 241 ), which is the most prevalent form, affects upward to 31 million U.S. adults. Arthritis is already the leading cause of disability in the United States, yet the number of affected individuals with arthritis and arthritis-attributable limitations in activity is anticipated to approach 67 million by the year 2030. Despite therapeutic advances in the medical treatment of inflammatory arthritic disorders, surgical intervention is eventually required in many patients who suffer from inflammatory arthritis. Furthermore, other than exercise and rehabilitation, surgery is often the only option for degenerative arthritis. The increasing prevalence of arthritis, the desire for higher activity levels, and improvements in surgical techniques have fueled the utilization of orthopedic surgery. By the year 2030, it is predicted that over 500,000 hip replacements and 3 million knee replacements will be performed annually in the United States.

Pathobiology

Arthritis results when damage to articular cartilage and accompanying inflammation of the synovium and joint result in the loss of the joint’s mechanical properties. Without the protective layer of articular cartilage, stiffness develops. Furthermore, the nociceptive and proprioceptive receptors in the periosteum are activated, thereby leading to pain.

Osteoarthritis ( Chapter 241 ), which is the most common cause of end-stage arthritis, is classified as primary when due to biochemical changes in the cartilage, or secondary if it results from systemic disease affecting the cartilage, joint damage from preexisting inflammatory joint disease, prior infection, previous surgery, congenital or developmental problems, or trauma. Mechanical overload and joint imbalance then lead to further degradation of cartilage. Important adaptive processes, such as subchondral sclerosis and the formation of osteophytes, occur in response to joint overload. Cysts may also form in the subarticular bone. Over time, the osteophytes or bone spurs lead to restricted range of motion ( Fig. 255-1 ).

By contrast, inflammatory arthritis (e.g., rheumatoid arthritis [ Chapter 243 ], psoriatic arthritis, and spondyloarthropathies [ Chapter 244 ]) targets the synovium. The subsequent release of inflammatory mediators leads to destruction of cartilage. In contrast to osteoarthritis, mechanical overload, bone sclerosis, and osteophytes are not seen. Rather, the inflammatory synovitis leads to characteristic loss of cartilage matrix, marginal bony erosions, and osteopenia ( Fig. 255-2 ).

In osteonecrosis ( Chapter 229 ), blood supply to the bone is compromised, thereby leading to necrosis of the bone that supports the articular surface. The most commonly affected joints are the hip, shoulder, and knee. As the condition progresses, the necrotic bone may collapse, thereby leading to the loss of articular integrity and progressive deterioration of cartilage. Other conditions that may lead to joint damage include metabolic disorders (e.g., chondrocalcinosis, gout), tumor (e.g., synovial chondromatosis), and bleeding disorders (e.g., hemophilia).

Osteotomy

In circumstances in which a structural abnormality around a joint has led to mechanical overload, an osteotomy (bone cutting) may be an option to correct alignment problems. The most common sites for osteotomy are the hip (to treat acetabular dysplasia) and the tibia (to realign the knee). In acetabular dysplasia, the hip socket is excessively shallow, thereby leading to abnormal stresses on the articular cartilage and premature osteoarthritis. An acetabular osteotomy can be performed in patients in whom cartilage still remains. By rotating the pelvic bones, a deeper socket can be formed, thereby reducing stresses on the cartilage and slowing the arthritic process. With tibial osteotomy, the knee joint can be realigned to direct forces away from the region of cartilage damage. Usually a varus (bow-legged) deformity indicates the medial compartment of the knee is excessively worn, and a tibial osteotomy can realign the joint to direct forces to the uninvolved lateral compartment. Typically, osteotomy is considered an option for patients who are younger than age 40 years; beyond this age, the loss of cartilage generally makes total joint arthroplasty the preferred approach.

Arthroscopy

Arthroscopic surgery is performed by inserting a camera and specialized instruments into a joint via small, puncture-type incisions. Arthroscopic surgery is effective in the treatment of intra-articular pathologies such as meniscal tears of the knee, labral tears of the hip, cartilage flaps, small chondral defects, and loose bodies. However, after the articular cartilage is significantly damaged, arthroscopic debridement is usually ineffective unless patients have mechanical symptoms such as locking and clicking. In some instances, underlying joint arthritis may lead to tears in the meniscus or labrum; if such a tear results in new mechanical symptoms, then arthroscopic surgery may be helpful in selected cases. The benefit of arthroscopic subacromial decompression for shoulder impingement syndrome is variable but appears to be minimal overall. ^,

In patients who have femoroacetabular impingement (impingement of the femoral neck upon the acetabular rim, typically during flexion and internal rotation), the repetitive contact between the femoral neck and acetabular rim is believed to result in labral tears, cartilage damage, and eventual arthritis. The bones of the femur and acetabulum can be reshaped by an osteochondroplasty, performed as an open or arthroscopic procedure, to provide good symptomatic relief in the short term. However, the long-term effects, specifically the impact on the future development of arthritis, have yet to be demonstrated for this procedure.