- HIV is a retrovirus, which encodes its genome in RNA and transcribes genome copies in DNA using the enzyme reverse transcriptase within host cells such as the human CD4 (T helper) lymphocyte.
- HIV infection is marked by a fall in the CD4 cell count with an associated decrease in immunity, particularly humoral immunity.
- HIV infection results in a syndrome known as acquired immune deficiency syndrome (AIDS).
- Despite the numerous advances made in antiretroviral therapies such as nucleoside analogues, protease inhibitors, fusion inhibitors and integrase inhibitors that reduce the viral load in the host serum and restore the numbers of host CD4 cells there is still no cure for HIV infection.
- HIV weakens the immune system and reduces a patient’s ability to fight infections.
- Early non-orthopaedic studies reported an increased risk of infections in HIV-positive patients with an absolute CD4 cell count of <200 cells/mm3or a viral load of >10,000 copies/ml.
- There is currently no agreement in the literature on whether a HIV-positive patient’s CD4 cell count or viral load influences the risk of post-orthopaedic implant surgical infection.
Orthopaedic surgery and HIV
- Orthopaedic surgery was dramatically influenced by the HIV pandemic.
- Early reports showed complication rates of 140% and mortality rates of 55–70%, this led to a pessimistic approach to surgery in HIV-positive patients.
- The initial perception was that these patients were prone to:
- Poor wound healing.
- High postoperative complication rates.
- A protracted postoperative period.
- Higher mortality rates.
- These early studies were skewed by the fact that these procedures were usually performed as emergencies presenting as a direct consequence of HIV.
- Effective antiretroviral therapy has dramatically improved the outlook of HIV-infected patients, and altered the nature of the surgical care that these patients require.
- If the patient’s CD4+ cell count is not depressed, the surgical outcome should be good.
- Initial studies reported infection rates as high as 24–40%; more recently studies have showed a 3.5% infection rate in patients with CD4 cell counts as low as 200.
- The recommendations are effective prophylactic antibiotics, clean operating environment, strict theatre discipline and careful soft-tissue handling.
- HIV has been reported as a worse prognostic indicator for adult respiratory distress syndrome (ARDS) following trauma.
- In open fractures, where contamination has already occurred, the frequency of wound infection is high in all published series (42% in HIV-positive patients compared with 11% in controls).
- Untreated HIV infection may delay, and sometimes prevent, fracture union. The effects of the disease on fracture healing increases with the increase in its severity.
- The non-union responds well to stable internal fixation and autologous bone grafting.
- There may be a risk of late sepsis around implants as the immunity of the patient wanes and the disease advances.
- This has been seen both following trauma and arthroplasty.
- Removal of instrumentation may be indicated as the disease advances. These late infections can be due to reactivation of latent bacteria or may be because of late haematogenous seeding.
- Most of the research in this regard was on HIV-positive haemophiliac patients.
- A large retrospective multicentre study found an increased rate of deep sepsis – as high as 18.7%. These patients are, however, at high risk of bleeding as well as bacteraemia associated with regular factor transfusions.
- The risk of sepsis seems to be lower in non-haemophiliac HIV-positive patients but literature remains lacking.
Other implants and elective surgery
- Elective surgery seems to be safe in HIV-positive patients with better outcomes seen in controlled disease.
- Harrison et al.2found that in the absence of preoperative wound contamination, there is no higher incidence of wound infection regardless of the CD4 cell count.
- Buehrer et al.3confirmed this in a similar HIV-positive haemophiliac study.
- The initial nihilistic surgical approach to HIV-positive patients seems to have been too cautious.
- With a few exceptions, most orthopaedic surgery can be undertaken safely in these patients, provided that one adheres to proper surgical principles.
- Surgical outcome of HIV-positive patients approaches that of the general population with good disease control.