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Ari-PekkaPuhto

Complications of Prosthetic Joints

Essentials

  • A specialist orthopaedic centre must be consulted early whenever complications are suspected.
  • Signs and symptoms of a postoperative infection must be recognised, the depth of the infection established and the causative organism identified.
  • Attention must be paid to preoperative eradication of all possible foci of infection.
  • Regular postoperative follow-up will ensure early recognition of complications. The emergence of symptoms in a previously asymptomatic joint must always be investigated.

Prosthetic joint infection

Classification and symptoms

  • Early postoperative infection
    • Within one month of surgery
    • Acute clinical picture: fever, redness, swelling, wound exudate
    • CRP markedly increased, leucocytosis
      • After surgery, CRP decreases individually and usually normalises within a few weeks. Serial CRP determinations should show a continuous, downward trend. However, for example in patients with rheumatoid arthritis, CRP may stay permanently above the normal reference range. An upward shift in CRP concentration is a worrisome sign and warrants further investigations.
    • Prolonged postoperative pain
      • The extent and duration of postoperative pain vary from patient to patient. Should the pain increase and prevent for example weight bearing on the limb, the presence of other complications should be considered, such as luxation or fracture.
  • Late chronic infection
    • More than one month after surgery
    • Pain persists after surgery
    • Symptoms are mild and variable
    • Often a long history
    • The patient usually remains afebrile
    • CRP usually only slightly increased, with or without leucocytosis
      • ESR is often slightly elevated, but may also be normal
    • The clinical picture resembles that of aseptic loosening of the prosthetic joint.
  • Haematogenous infection
    • Acute clinical picture: fever, generalised symptoms, sepsis, pain, redness, swelling
    • CRP markedly increased, leucocytosis, positive blood cultures
    • Prosthetic joint previously symptomless
    • The foci of infection identifiable

Management

  • A specialist orthopaedic centre should always be consulted before carrying out investigations or starting treatment.
  • The identification of the causative bacteria forms the cornerstone of management. Antimicrobial drugs must not be prescribed even in the presence of a mild wound infection before obtaining reliable culture samples of the joint and consulting a specialist orthopaedic centre.
    • It is not possible to differentiate between a superficial wound infection and a deep prosthetic infection with visual inspection alone. Redness and warmth are both part of the normal wound healing process. Sutures and clips often irritate the skin, and a small amount of exudate is normal from the clip sites when they are being removed.
    • If a true wound infection is suspected and antimicrobial drugs are considered, the possibility of a deep infection must be excluded. Persistent discharge from the wound is strongly suggestive of an infection of the prosthetic joint as is wound dehiscence.
    • A foreign body will quickly be surrounded by a bacterial biofilm which will provide protection against antimicrobial drugs. A course of oral antimicrobial drug will not therefore be able to treat a deep prosthetic infection, but it may interfere with the identification of the bacteria and thus prevent the choice of a correct drug.
  • Early postoperative and haematogenous prosthetic joint infection
    • Prosthesis salvage may be possible.
    • Debridement in the operating theatre with appropriate culture samples
    • Targeted antimicrobial therapy with duration of several weeks (with 1-3 antimicrobial drugs)
    • In cases where the infection recurs during or after the treatment, the prosthesis should be removed. A new prosthesis can be implanted in the same operation (one-stage revision surgery) or, alternatively, later in another operation either during or after the antimicrobial therapy (two-stage revision surgery).
  • Late chronic prosthetic joint infection
    • Prosthesis salvage is not usually possible.
    • One-stage or two-stage revision surgery
    • Targeted antimicrobial therapy with duration of several weeks
  • If any problems are encountered in primary health care as regards the antimicrobial therapy, the specialist team caring for the patient should be contacted.

Prevention

  • It is advisable to consult the orthopaedic team preoperatively regarding any conditions that may prove to be hazardous for the surgery.
  • Preoperative eradication of all possible foci of infection; if in doubt consult an infectious-disease specialist.
    • Skin
      • Integrity of the skin is important. Typical problem sites include the areas between the toes and under the breasts as well as flexural surfaces.
      • An infected skin wound or chronic leg ulcer, for example, are contraindications for surgery.
    • Urine
      • Treatment guidelines for asymptomatic bacteriuria vary from hospital to hospital. Perioperative antimicrobial prophylaxis is usually sufficient to treat bacteriuria, but it will not be effective, for example, against pseudomonas or enterococci.
    • Teeth
      • A dental check-up is recommended to patients who have not visited a dentist regularly, who smoke a lot, who use or have used plenty of alcohol or drugs, or who due to infections have had teeth removed.
      • Denture wearers should also consult a dentist should any gum problems exist.
  • Skin and soft tissue infection
    • The most common cause of a late prosthetic joint infection is bacteraemia of cutaneous origin.
      • Prevention of all sores and ulcers
      • Careful management of skin infections
      • Antimicrobial cover during all procedures involving infected skin

Wear and loosening of a prosthetic joint

  • A macrophage/histiocytic reaction is elicited by wear particles, which are generated by the articulating surfaces of the joint, as well as by bone cement debris and any other micron-size particulate. This will lead to osteolysis and a gradual loosening of the prosthetic components from the bone.
  • Osteolysis is evident in x-rays as a dark zone that stands out from its surroundings within the bone, next to the prosthetic joint component (a radiolucent line).
  • A cementless prosthetic joint component, in particular, may remain fairly asymptomatic, even in cases where the osteolytic area beneath is quite substantial.
  • Loosening of a prosthetic joint is diagnosed when radiologically positive findings are combined with pain on weight bearing.
  • Regular monitoring is essential to ensure early identification of prosthetic joint complications, such as loosening or wear of the plastic components. This will allow the employment of more minor surgical procedures.
  • Monitoring of the prosthetic joint may be organized as remote monitoring, in which the patient fills out a questionnaire about symptoms and plain radiographs are taken.
    • Monitoring of a prosthetic hip joint starts at 5 years after surgery and takes place every 5 years.
    • Monitoring of a prosthetic knee joint starts at 10 years after surgery and thereafter takes place every 5 years.
    • If required, the monitoring intervals may be shorter (e.g. metal on metal prostheses)
  • Possible symptoms associated with a prosthetic joint complication include (i.e. the emergence of symptoms in a previously asymptomatic joint):
    • pain during exercise
    • audible sounds (a squeak, clunk etc.)
    • joint instability
    • swelling of the joint.
  • If symptoms, clinical signs and x-rays are suggestive of component loosening or any other prosthetic joint complication, an orthopaedic surgeon should be consulted.

X-ray diagnostics in prosthetic joint problems

  • Two projections should always be taken, i.e. anteroposterior projection of the hip and lateral projection of the side under investigation (not Lauenstein projection). The lateral projection will show any changes in the anteversion angle of the cup as well as the sides of the femoral component. When x-raying a knee prosthesis, a posteroanterior flexion projection (or an anteroposterior projection) and lateral projection should be taken with the patient standing up.
  • The new films should be compared with previous ones; this will facilitate the identification of possible changes.
  • Findings suggestive of loosening
    • a radiolucent line of 2 mm or more between the cement and bone or between the prosthetic component and cement
    • movement of the cup/cement assembly, or a cementless cup component, when compared with previous x-rays (the cup is likely to be loose)
    • zones of osteolysis around a prosthetic component or cement
    • fracture of the cement mantle indicating loosening of the stem component
    • a pronounced periosteal reaction and thickening of the cortex on the lateral side of the diaphysis (the stem is compressing the cortex)
    • migration of the stem and cement assembly down the marrow cavity
  • Findings suggestive of wear
    • the ball has moved cranially within the cup (when measured with a ruler the distance of the ball from the lower edge of the cup is more than its distance from the upper edge)
    • in a knee prosthesis, asymmetry of the plastic-induced gap between the components.

Reaction to metal in association with metal-on-metal hip prostheses

  • Metal ions released from a hip prosthesis may cause an inflammatory tissue reaction that leads to the development of a so-called pseudotumour and eventually to loosening of the components. It is usually associated with increased concentrations of metal ions in the blood as well as fluid accumulation around the implant.
  • In a considerable number of patients the reaction to metal may produce no or only few symptoms.
  • Unusual symptoms in a hip with a metal-on-metal prosthesis include e.g. constant groin or buttock pains, abnormal sounds coming from the hip (squeaking, grinding or clicking), feeling of pressure or swelling around the hip and a lump felt in the hip region or in the groin.
  • The situation of patients with a metal-on-metal hip prosthesis should be assessed every 2 years with symptom questionnaires, plain x-rays and whole blood assays for chromium and cobalt ions as well as with clinical examination if needed.
  • If there are symptoms from the metal-on-metal hip implant or if the whole blood chromium or cobalt concentration exceeds 5 µg/l the patient is referred to the unit responsible for joint replacement surgery for further investigations. The primary investigation there is a MARS MRI scan.

Erosion of the native acetabulum

  • Possible complication after hemiarthroplasty of the hip
  • Treatment only if symptomatic
  • Revision surgery is not always indicated. The speed of erosion varies, and the lodging of the trochanter against the rim of the acetabulum may halt the progression.

References

  • Tande AJ, Patel R. Prosthetic joint infection. Clin Microbiol Rev 2014;27(2):302-45. [PubMed]