Definition

Total hip arthroplasty (THA), commonly called hip replacement surgery, involves the reconstruction of a diseased, damaged, or ankylosed hip joint. The most common causes of adult hip disease are osteoarthritis, inflammatory arthritides, avascular necrosis, post-traumatic degenerative joint disease, congenital hip disease, oncologic bone disease, and infection involving the hip joint. The surgical treatment of hip arthritides has evolved from the first excisional arthroplasty by Anthony White in 1821 into the modern THA [1]. The modern era of hip joint replacement began in the late 1960s when Sir John Charnley combined a stainless steel femoral component with a polyethylene socket fixed to the adjacent acetabulum with polymethyl methacrylate (cement). Since that time, arthroplasty of the hip joint has become an accepted and standard treatment of common adult hip joint disease. Modern hip arthroplasty surgery has resulted in the restoration of pain-free motion and improved quality of life for millions [2]. Total joint arthroplasty, including hip and knee, has become the most common elective surgical procedure performed in the United States, with more than one million performed in 2009 [3]. The Centers for Disease Control and Prevention reported that 327,000 total hip replacements were performed in the United States in 2009 [3].

Hip joint arthroplasty can be divided into either THA, which provides a prosthetic replacement of the proximal femur and acetabulum, or hemiarthroplasty, which replaces the proximal femur while leaving the native acetabulum intact. Hip hemiarthroplasty is reserved for patients with a healthy articular surface in the acetabulum and is most commonly seen after proximal femur fractures. The focus of this chapter is on THA, which is the preferred surgical option for patients with degenerative changes affecting both the femur and acetabulum. Further categorization for hip arthroplasty can be made by prosthetic hardware components, surgical approach, or fixation method of the prosthesis (cement versus biologic or “press-fit” integration). Surgical decision-making for hardware type, approach, and prosthetic fixation is beyond the scope of this chapter, but it is important to note that there are no published consensus guidelines on best prostheses, approach, or fixation method among surgeons performing total hip arthroplasties.

Symptoms

The primary symptom of hip disease is groin pain, but patients may also have associated back and knee pain. Patients may describe a decline in mobility, self-care, and activities of daily living. They may present with an abnormal gait or may describe difficulty in walking long distances and need for an assistive device. Donning their shoes or socks and taking them off and getting in and out of the seated position may be difficult daily activities. Inability to participate in recreational activities or light sports may be a presenting complaint.

Physical Examination

Patients with hip disease are likely to have physical examination findings that will require continued attention postoperatively (Table 61.1). The examiner should examine both hips, knees, and back for range of motion. Decreased range of motion of the affected hip will be found and may be the first physical examination finding in cases of mild disease. Also, a thorough neurovascular examination of all extremities should be performed. One of the most commonly observed examination findings is an antalgic (painful) gait pattern representing a combination of pain that inhibits motion, structural loss of joint motion, avoidance behavior, and weakness. Hip pain or weakness of the hip abductors can result in contralateral pelvic tilt or drop (Trendelenburg sign) with ipsilateral weight bearing (Fig. 61.1). Muscle weakness is typically not true neurologic weakness but rather represents a disuse weakness associated with pain and avoidance. A hip flexion contracture may be observed with the Thomas test (Fig. 61.2), and accentuated lumbar lordosis may be seen in those with a hip flexion contracture, which may result in secondary mechanical low back pain due to alteration of normal spine mechanics. A limb length discrepancy may be observed, with the affected hip being the shorter limb.

Functional Limitations

Functional limitations from severe hip disease include difficulty in walking and with all mobility, even rising from a seated position, because of pain and weakness. This may affect a patient’s ability to dress, to bathe, to perform household chores, to participate in recreational activities, and to work outside the home. The goal of THA is to improve pain and consequently to improve function with activities of daily living.

Diagnostic Studies

Plain radiography remains the primary imaging tool for evaluation of hip disease and for postoperative assessment of THA. On radiographic examination, significant loss of joint cartilage as demonstrated by joint space narrowing, joint incongruity, osteophyte formation, subchondral cysts, and sclerosis are seen in individuals being considered for THA (Fig. 61.3). Many postoperative complications after THA can be evaluated by plain radiography. In patients thought to have a dislocation after THA, radiographs should be obtained urgently because a true dislocation must be relocated expediently (Fig. 61.4). Plain radiographs are also obtained in patients thought to have prosthetic loosening or periprosthetic fracture (Fig. 61.5). If plain radiographs do not show pathologic changes in a patient with enigmatic hip pain after THA, magnetic resonance imaging can be done with minimal artifact and can demonstrate disease in the periprosthetic soft tissues, including synovitis, periprosthetic inflammation, osteolysis, and iliopsoas tendinitis [4]. A computed tomography scan or bone scan may be part of the evaluation for osteolysis or loosening and infection.