Introduction
Background
Arthroplasty of the hip may be categorized as a total hip arthroplasty or a hemiarthroplasty. In a total hip arthroplasty, the articular surfaces of both the acetabulum and femur are replaced. This involves either replacement of the femoral head and neck (conventional total hip arthroplasty) (see Images 1-7) or replacement of the surface of the femoral head (resurfacing total hip arthroplasty) (see Image 8); both procedures also replace the acetabulum.
In contrast to a total hip arthroplasty, a hemiarthroplasty involves replacement of the articular surface of the femoral head without surgical alteration to the acetabular articular surface. This may involve replacement of the femoral head and neck (unipolar hemiarthroplasty) (see Images 9-10), replacement of the femoral head and neck with an additional acetabular cup that is not attached to the pelvis (bipolar hemiarthroplasty) (see Images 11-12), or replacement of the surface of the femoral head (resurfacing hemiarthroplasty) (see Image 35). With a bipolar hemiarthroplasty, there is normal motion between the femoral head and acetabular cup, and between the acetabular cup and native acetabulum (see Image 13).
The hip joint may be replaced with a variety of materials, including metal, polyethylene, and ceramic. There are also various methods of arthroplasty fixation, such as polymethylmethacrylate (PMMA) cement and screw fixation, although cementless press fit and porous ingrowth arthroplasties may also be used. Arthroplasty materials and fixation are discussed in the Anatomy section, below.
Imaging of a hip arthroplasty and its complications primarily relies on the information that is obtained from routine radiography, although there are specific roles for other imaging techniques, such as arthrography, computed tomography (CT) scanning, magnetic resonance imaging (MRI), ultrasonography, and nuclear medicine.
For excellent patient education resources, visit eMedicine's Arthritis Center and Foot, Ankle, Knee, and Hip Center. Also, see eMedicine's patient education article Total Hip Replacement.
Related eMedicine topics:
Acetabulum Fractures
Fractures, Hip
Osteonecrosis, Hip
Related Medscape topics:
Resource Center Fracture
Resource Center Joint Disorders
Resource Center Rheumatoid Arthritis
CME Glucosamine May Be No Better Than Placebo for Hip Osteoarthritis
CME/CE New Guidelines Issued for Management of Hip and Knee Osteoarthritis
Pathophysiology
Common indications for a total hip arthroplasty include conditions that affect both the articular surfaces of the acetabulum and femur, such as osteoarthritis. A resurfacing total hip arthroplasty is considered in younger patients with osteoarthritis and good bone stock (ie, no osteopenia or excessive bone loss). A hemiarthroplasty is commonly used when avascular necrosis of the femoral head is present, or if there is a displaced femoral neck fracture with significant risk of developing avascular necrosis, without hip joint osteoarthritis.
Complications of hip arthroplasty include implant fracture, dislocation, mechanical loosening, infection, heterotopic bone formation, and particle disease (also termed aggressive granulomatosis, which represents a foreign-body reaction to implant debris that causes focal osteolysis).1
Related eMedicine topics:
Acetabulum Fractures
Avascular Necrosis, Femoral Head
Heterotopic Ossification
Osteoarthritis
Osteonecrosis, Hip
Related Medscape topic:
Specialty Site Orthopaedics
Frequency
United States
More than 120,000 total hip arthroplasties are performed annually.2
International
Worldwide, approximately 800,000 total hip arthroplasties are performed annually.2
Mortality/Morbidity
A 3% prevalence of prosthetic loosening is observed at 11 years after hip replacement, and there is a 1% prevalence of prosthetic infection.
Anatomy
Arthroplasty Components
Acetabulum components include the following:
- Polyethylene (with or without metal backing) (see Images 1-4 and 11-13)
- Cobalt-chromium metal (see Image 5)
- Ceramic (see Images 6-7).
Femoral components include the following:
- Metal femoral stem (cobalt-chromium or titanium alloy) (see Images 1-13)
- Metal (see Image 5) or ceramic (see Images 6-7) femoral head.
Arthroplasty Articulations
The most common materials used for a total hip replacement articulation are a metal femoral head (cobalt-chromium), which articulates with an acetabular cup (polyethylene with metal backing) (see Images 1-3). Newer techniques that produce highly cross-linked polyethylene reduce wear and subsequent particle disease. Another material that is used for the femoral head is ceramic, articulating with either a polyethylene (see Image 4) or ceramic cup (see Images 6-7). Metal-on-metal articulations are also used as a way to reduce particle shedding and osteolysis (see Image 5).
Arthroplasty Fixation: Acetabulum
Fixation of the acetabular component to bone may involve methylmethacrylate cement (see Image 3), spikes, or screws (see Images 2 and 5). Cementless components may be press fit or may have a roughened surface for bone ingrowth (see Images 1, 4, and 6-8). Of note, the acetabular cup of a bipolar hemiarthroplasty is not attached to the acetabulum; therefore, normal bone condensation of the acetabular roof (called the sourcil) remains, and normal lucency from hyaline cartilage is seen between the acetabular cup and native acetabulum (see Image 11). Motion may also be seen between the acetabular cup and the native acetabulum; mild changes in the position of the acetabular cup should not be misinterpreted as abnormal (see Images 12-13). These features are absent in a total hip arthroplasty in which the acetabulum has been reamed, and the acetabular cup should be stationary.
Arthroplasty Fixation: Femur
Fixation of the femoral component to bone may also involve methylmethacrylate cement (see Images 1, 3, 5, 11). A cement restrictor or centralizer may be seen distal to the femoral stem in this setting (see Image 14). As with the acetabular cementless components, those of the femur may be press fit (see Image 2) or may have a roughened surface for bone ingrowth (see Image 4), which appears as spot welds (see Image 15). In addition, femoral cerclage wires or cables are often used to secure a trochanteric osteotomy or bone graft after a hip arthroplasty revision (see Images 6, 16, 52).
Preferred Examination
Radiography is the primary imaging method for the evaluation of hip arthroplasties (See Radiograph, below).
Limitations of Techniques
Specific issues exist that are related to the choice of the hip arthroplasty material that is used and to the type of the arthroplasty itself.
The most common scenario for a replaced femoral head and acetabular articulation in a total hip arthroplasty is to use a cobalt-chromium alloy metal femoral head and a polyethylene cup (with metal backing) articulation. A complication related to this combination is polyethylene wear and subsequent inflammation and osteolysis from particle disease. In order to reduce component wear, ceramic femoral heads have also been used with a polyethylene acetabular cup, as well as a combination of a ceramic head and a ceramic cup. Although not exclusive to ceramic-on-ceramic articulation, patients have complained of "squeaking" during ambulation.3 Ceramic head components may also fail or fragment.
There has been a renewed interested in metal-on-metal articulations with the use of a larger femoral head component, which has the advantage of a lower frequency of hip dislocations. The metal-on-metal articulation also has less wear compared with that of polyethylene components, and the particles are smaller and associated with less inflammation. Of concern, however, are reports that chromium and cobalt metal ions have been found in the blood and urine after metal-on-metal arthroplasties. Although a study by Miller et al quoted an increased incidence of leukemia from such procedures, there were no statistical differences between the metal-on-metal and the metal-on-polyethylene articulations.4
With regard to the type of arthroplasty, resurfacing metal-on-metal arthroplasties have been considered for younger patients who have osteoarthritis and normal proximal femur bone quality.5 The advantage of this surgery is that the femoral neck is preserved, which may be advantageous to the patient, who may later need a conventional arthroplasty. Patient selection is key to the success of resurfacing arthroplasties. Thinning of the femoral neck has been described after this type of surgery (possibly related to stress shielding), although this finding is not associated with failure.5 The incidence of femoral neck fracture after hip resurfacing is approximately 1.25%.5
Differential Diagnoses
Other Problems to Be Considered
Acetabulum Fractures Avascular Necrosis, Femoral Head
Femoral Neck, Fractures
Fractures, Hip
Immune Response to Implants
Infection
Intertrochanteric Hip Fractures
Osteoarthritis
Osteonecrosis, Hip
Total Joint Replacement Rehabilitation
More on Hip Replacement |
 Overview: Hip Replacement |
| Imaging: Hip Replacement |
| Follow-up: Hip Replacement |
| Multimedia: Hip Replacement |
| References |
| Next Page » |
References
Tigges S, Stiles RG, Roberson JR. Complications of hip arthroplasty causing periprosthetic radiolucency on plain radiographs. AJR Am J Roentgenol. Jun 1994;162(6):1387-91. [Medline]. [Full Text].
White LM, Kim JK, Mehta M, et al. Complications of total hip arthroplasty: MR imaging-initial experience. Radiology. Apr 2000;215(1):254-62. [Medline]. [Full Text].
Huo MH, Gilbert NF, Parvizi J. What's new in total hip arthroplasty. J Bone Joint Surg Am. Aug 2007;89(8):1874-85. [Medline]. [Full Text].
Miller TT. Imaging of hip arthroplasty. Semin Musculoskelet Radiol. Mar 2006;10(1):30-46. [Medline].
Amstutz HC, Campbell P, Le Duff MJ. Metal-on-metal hip resurfacing: what have we learned?. Instr Course Lect. 2007;56:149-61. [Medline].
Manaster BJ. From the RSNA refresher courses. Total hip arthroplasty: radiographic evaluation. Radiographics. May 1996;16(3):645-60. [Medline]. [Full Text].
Weissman BN. Imaging of total hip replacement. Radiology. Mar 1997;202(3):611-23. [Medline]. [Full Text].
Weissman BNW, Sledge CB. The hip. Orthopedic Radiology. Philadelphia, Pa: WB Saunders Co; 1991:385-495.
Tigges S, Stiles RG, Roberson JR. Appearance of septic hip prostheses on plain radiographs. AJR Am J Roentgenol. Aug 1994;163(2):377-80. [Medline]. [Full Text].
Berquist TH, Bender CE, Maus TP, Ward EM, Rand JA. Pseudobursae: a useful finding in patients with painful hip arthroplasty. AJR Am J Roentgenol. Jan 1987;148(1):103-6. [Medline]. [Full Text].
Kitamura N, Pappedemos PC, Duffy PR 3rd, et al. The value of anteroposterior pelvic radiographs for evaluating pelvic osteolysis. Clin Orthop Relat Res. Dec 2006;453:239-45. [Medline].
Buckwalter KA, Parr JA, Choplin RH, Capello WN. Multichannel CT imaging of orthopedic hardware and implants. Semin Musculoskelet Radiol. Mar 2006;10(1):86-97. [Medline].
Naraghi AM, White LM. Magnetic resonance imaging of joint replacements. Semin Musculoskelet Radiol. Mar 2006;10(1):98-106. [Medline].
Weybright PN, Jacobson JA, Murry KH, et al. Limited effectiveness of sonography in revealing hip joint effusion: preliminary results in 21 adult patients with native and postoperative hips. AJR Am J Roentgenol. Jul 2003;181(1):215-8. [Medline]. [Full Text].
van Holsbeeck MT, Eyler WR, Sherman LS, et al. Detection of infection in loosened hip prostheses: efficacy of sonography. AJR Am J Roentgenol. Aug 1994;163(2):381-4. [Medline]. [Full Text].
Rezig R, Copercini M, Montet X, Martinoli C, Bianchi S. Ultrasound diagnosis of anterior iliopsoas impingement in total hip replacement. Skeletal Radiol. Feb 2004;33(2):112-6. [Medline].
Lachiewicz PF, Rogers GD, Thomason HC. Aspiration of the hip joint before revision total hip arthroplasty. Clinical and laboratory factors influencing attainment of a positive culture. J Bone Joint Surg Am. May 1996;78(5):749-54. [Medline].
Wank R, Miller TT, Shapiro JF. Sonographically guided injection of anesthetic for iliopsoas tendinopathy after total hip arthroplasty. J Clin Ultrasound. Sep 2004;32(7):354-7. [Medline].
Einsiedel T, Gebhard F, Bregolato I, et al. Proximal cement fixation in total hip arthroplasty-first results with a new stem design. Int Orthop. Jun 2008;32(3):295-306. [Medline].
González Della Valle A, Comba F, Taveras N, Salvati EA. The utility and precision of analogue and digital preoperative planning for total hip arthroplasty. Int Orthop. Jun 2008;32(3):289-94. [Medline].
Mouzopoulos G, Stamatakos M, Arabatzi H, et al. The four-year functional result after a displaced subcapital hip fracture treated with three different surgical options. Int Orthop. Jun 2008;32(3):367-73. [Medline].
Wedemeyer C, Neuerburg C, Heep H, et al. Jumbo cups for revision of acetabular defects after total hip arthroplasty: a retrospective review of a case series. Arch Orthop Trauma Surg. Jun 2008;128(6):545-50. [Medline].
Further Reading
Keywords
hip arthroplasty, hip prosthesis, THR, THA, heterotopic ossification, particle disease, periprosthetic lucency, aggressive granulomatosis, hemiarthroplasty, acetabulum, methylmethacrylate, metal-on-metal articulation, metal-on-metal arthroplasty, cemented component, cementless component, joint aspiration
