Dermal discoloration due to osmium tetroxide.

INTRODUCTION: Osmium tetroxide is a strong oxidizing agent. After dermal exposure to osmium tetroxide, skin discoloration and red papules can occur. We describe a patient with skin discoloration due to osmium tetroxide. CASE SUMMARY: A 25-year-old postgraduate student unintentionally exposed his hand to osmium tetroxide while working in a laboratory setting. After immediate washing, he sought medical care due to left middle finger discoloration. He reported no discomfort in the affected area. Thorough water rinsing was continued, and corticosteroid ointment was applied. IMAGES: Our patient developed dark brown pigmentation on the ventral side of the left middle finger. The pigmentation disappeared one week later. CONCLUSION: Osmium tetroxide may induce dark brown skin discoloration.

Osmic acid revisited: factors that predict a favourable response.

OBJECTIVE: Chemical synovectomy with osmic acid has been used for many years in the treatment of chronic synovitis that is unresponsive to systemic treatment and intra-articular corticosteroid. Our aims were to compare the safety and the efficacy of this procedure with that of alternative treatment modalities, and to identify any factors that may predict the response to treatment. METHODS: A retrospective review of 103 osmic acid injections was performed in 65 patients with chronic knee synovitis, between 1992 and 1998. After a clinical review 6 weeks after injection, the length of remission was determined by telephone survey. Thirty-six months of follow-up was available for 96 injections, with a minimum of 12 months for the remainder. Remission was defined as complete absence of pain and swelling. RESULTS: Sixty-nine (67.0%) knee joints remained completely free of pain and swelling at 6 months, falling to 52 (50.5%) at 12 months, 32 (31.1%) at 24 months, and 19 (18.4%) at 36 months. Knees with mild radiological changes experienced significantly better results compared with those with moderate or severe changes (P=0.006 and 0.046 respectively). In patients undergoing bilateral injections, there was a correlation between the duration of remission achieved for each of the two knees (r=0.83, P < 0.01). A correlation was also observed between the responses obtained after first and repeated synovectomies of the same knee (r=0.62, P < 0.05). Eighty-six per cent of injections were uncomplicated. Side-effects included pain, which followed 13 injections (12.4%), and two skin burns. CONCLUSIONS: Long-term complete remission was achieved in 18.4% of knees. This treatment may be best reserved for joints with less severe radiological changes. The response to a first osmic acid injection has a strong predictive value when considering further treatment of the same or the contralateral joint.

A retrospective study on chemical and radioactive synovectomy in severe haemophilia patients with recurrent haemarthrosis.

Between 1970 and 1994, 116 chemical and 90 radioactive synovectomies were performed in 107 patients with severe haemophilia and two with type 3 von Willebrand's disease. The products used were osmic acid (OA) in 100 cases, 90-Yttrium in 35 cases, 186-Rhenium in 48, 169-Erbium in two, hexacetonide triamcinolone in 16 and radioactive gold in five cases. The use of radioactive colloids is not allowed in France in patients under 15 years of age. Twenty-nine patients had more than one synovectomy per joint. All patients were evaluated for 6 months post-synovectomy, using both a clinical and a radiological score. Six months after synovectomy, a good or excellent result was obtained for 81% of the joints treated with isotopes, compared with 44% of those treated with OA, P<0.001. This superiority of isotopes over osmic acid was still observed after 6 months for the 89 joints that were re-evaluated, with follow-up ranging from 1 to 9 years. It was possible to calculate a radiological score in 84 cases. With OA the best results were from the joints with the lowest scores pre-synovectomy (<7). No correlation could be established between the clinical and the radiological scores, due to the small size of the sample. In summary: (1) chemical and radioactive synovectomy are simple and safe procedures for haemophilic arthropathy, (2) in our series, after 6 months the efficacy of isotopic synovectomy was greater than that of chemical synovectomy, and this benefit seems to persist after 6 months, and up to 9 years in the group of patients with longer-term follow-up.

Osmium tetroxide in antigen-induced arthritis: failure to inhibit joint destruction.

Antigen induced arthritis (AIA) was elicited in 28 adult rabbits using ovalbumin. All animals developed an intensive monarthritis manifested by local heat and swelling. Two, 7 and 21 days later, respectively, 0.3 ml of 1 per cent OsO4 was injected into the arthritic knees of three groups of 9 rabbits. The rabbits were killed 1, 3 and 6 months later. No modifying influence on the severe to complete cartilage destruction was evident. One group of 8 rabbits received only OsO4 and the cartilage of these animals remained intact after 6 months.

Intra-articular osmic acid in rheumatoid arthritis: five years' experience.

Two hundred and one patients (305 knees) with rheumatoid arthritis received intra-articular osmic acid in one or both knees. Assessment was based on pain relief, warmth, tenderness, size and presence of effusion, degree of synovial thickening and range of pain-free movement. Satisfactory results were obtained in 61% at one year gradually reducing to 22% over a five-year period. If only those knees with none or minimal joint damage were considered, then a satisfactory result was obtained in a higher percentage, 74% at one year and 38% at five years.

[Radiological opacities after intra-articular injection of osmic acid. Relationship with the injection site (author's transl)]. / Opacités radiologiques après synoviorthèse du genou à l'acide osmique. Relation avec le site d'injection.

Abnormal radiological opacities are sometimes observed after intra-articular injection of osmic acid. These opacities are radio-opaque because osmium is a heavy metal (atomic number = 76). They are usually found near the suprapatellar pouch which is the usual injection site. A parasynovial injection (or back flow from the joint cavity) of some of the osmic solution, followed by concentration and fixation of the osmic deposits at this level, seems to be the cause of these radiological opacities. This could be the reason for the poor clinical results encountered in some cases of osmic acid therapy followed by such deposits.

Reversible renal side effects of intra-articular osmic acid injection.

In 101 patients treated for knee joint hydrops with intra-articular osmic acid injection, an increased incidence of proteinuria and microscopic haematuria was noted on the first day after injection. This increase subsided rapidly and had disappeared 3 days after the injection. Three patients showed transient glycosuria. No signs of permanent renal damage appeared in any patient.

Absence of increased frequency of degenerative joint changes after osmic acid injections.

Fifty-two adults and 31 children, who were treated with osmic acid for one knee joint, were observed for 8-18 years. No other local treatment of the knee joints was given. In adults no difference was seen in clinical or radiological findings between joints treated and not treated with osmic acid. The age of the patient had a marked influence on the development of degenerative joint disease. In children, radiological deterioration of the knee joints was marked in joints affected by radiological changes even before treatment. It is concluded that though osmic acid causes superficial damage to the cartilage, it has no significant clinical relevance. Osmic acid can still be recommended as a simple remedy in the treatment of knee joint synovitis, in both adults and children.