**2.4.2 Acute chest syndrome**

Acute chest syndrome is a specificity of SCD and affects around 20% of the patients. A combination of thoracic pain, fever and infiltrates on thoracic x-ray characterizes this syndrome. The etiology is multifactorial including pulmonary embolism, microvascular occlusion and infection Severity varies, but 13% of patients require mechanical ventilation and 3% may die. In a post operative period of any arthroplasty procedure in SCD patient, this syndrome should be seriously considered in establishing etiologies of acute chest pain. In fact, it prevention and management include respiratory support, antibiotics, blood transfusions and deep venous thromboses prophylaxis/therapy. At times corticosteroids may be indicated.

### **2.4.3 Infection**

Susceptibility to infection is an issue in SCD. Many of these patients are immunocompromised because of autosplenectomy and osteonecrotic tissues tend to be colonized by Gram negative organisms. Several organisms have been identified as important causes of infection including S pneumoniae, H influenza, and non-typhi Salmonella species and appropriate antibiotic prophylaxis and immunization must be instituted in these patients. Therefore, a systematic preoperative investigation should be undertaken prior to any Arthroplasty procedure in a SCD patient to rule out occult infection; this should a least include urine culture, ENT consultation and dental examination and corrections. If there is a suspicion of infectious foyers a full antibiotic

Arthroplasty in HIV/SCD Carriers 493

SCD have been incriminated as high risk factor or secondary aseptic necrosis, mainly of the hip. Provided the standard treatment of aseptic necrosis of the Hip is total hip arthroplasty, it become evident although rare and not reported currently, combination of both condition (SCD& HIV) in patients demanding arthroplasty, may in the next future, become a challenging issue. There is no evidence base on this precise issue; however, since the above both section A and B have been focused respectively on arthroplasty in HIV carriers in one hand, and in another one, Arthroplasty in SCD, knowing about HIV carriage in SCD patients may help to set up our thinking regarding arthroplasty in patients with both

As it has been said above, the literature on HIV carriage in SCD patients is very scars, due to the paucity of patients themselves. In fact, the clinical experience in Central Africa where HIV carriage is higher than 10% in general population, shows that this rate is not significantly higher in homozygous HbSS patients. Further more, as the large majority of HbSS homozygous patients are also sexually active, it make sense to believe that the HIV infection in these specific set, is got through the same pathways with the general population. One of the rare related paper we could found regarding this matter is the one of Bagasra O et al; it suggests that, in patients with both SS and HIV-1 infection, the retroviral disease may be ameliorated by host factors of which absence of splenic function prior to HIV-1 contamination may be one. In another term, this author assume that HbSS carriage makes the body more resistant to HIV process as into his experimental case-control study of ten years follow-up, both the CD4 count and the Viral load were better in HbSS patients with HIV infection compare to HbAA counter part with the same viral infection. This may be explained by the fact that, as the spleen and lymph nodes are major sites of human immunodeficiency virus type 1 replication, mutation, and genetic variation in vivo; and as a major portion of this lymphatic tissue, such as the spleen, is removed or otherwise is unavailable for invasion by the HIV-1 virus, the course of this infection is altered. The clinical consequence is a prolonged symptom-free interval or even increased survival that we experience in daily clinical follow up of homozygous HbSS patients. Into the contrary, as it was reported by Sellier P et al, no significant difference in HIV infection progression is observed between heterozygous SCD carriers with HIV and their normal Hemoglobin

Therefore, as far as HIV carriage is concerned in SCD patients, we should always distinguish homozygous patients in which, the expected course of retroviral process is slow than usual in one side, and in the other side, heterozygous patient in which it does not differ from that of the non SCD-non HIV patients. The same differentiation may be necessary

If we agree to distinguish Homozygous patients from their heterozygous counterpart

Regarding first homozygous HbSS patients, to the best of our knowledge, no evidence exist on the use of ARVT on them. However, on observing a short cohort of 5 patients in our practice at the Central Hospital of Yaoundé in Cameroun in to the last 5 years, our standard

regarding the HIV carriage, it makes sense to do the same in the matter of ARVT.

regarding the management of antiretroviral therapy (ARVT) in this field.

conditions.

**3.2 HIV carriage in SCD patients** 

counter part with the same virus.

**3.3 Antiretroviral therapy in SCD patients** 

treatment should be undertaken with normalization of biological markers prior to the joint procedure. After arthroplasty, bone fragments from joint resection and reaming should also be send for bacterial analysis; if positive, a specific antibiotic testing should be undertaken. Subsequently, a long term antibiotic therapy should be undertaken in collaboration with the infectious diseases team, and till the normalization of biological infectious markers.
