Treatment with acetaminophen is appropriate for this patient with knee osteoarthritis (OA). The presence of progressive knee pain in this older individual that is worse with walking and is accompanied by unicompartmental joint-space narrowing and osteophytosis in the absence of extensive inflammation is pathognomonic for OA. Although OA includes a component of low-level inflammation, the goal of treatment is relief of pain and restoration of function. Most treatment guidelines suggest the initial use of acetaminophen for pain control in patients with knee OA. Acetaminophen is usually at least moderately effective in OA management; at doses of up to 3 to 4 g/d, it is considered safe and well tolerated. Additionally, it causes little or no gastrointestinal intolerance in most patients, does not affect blood pressure, and has significantly less nephrotoxicity than NSAIDs.
Of note, results from a recently published meta-analysis examining 74 randomized trials with almost 59,000 patients suggest that single-agent acetaminophen is ineffective for the treatment of knee and hip OA and that NSAIDs should be first-line therapy. It is unclear whether guidelines will change because of this meta-analysis (da Costa et al).
Both selective cyclooxygenase (COX)-2 inhibitors and traditional nonselective NSAIDs (such as ibuprofen) are of proven benefit in patients with OA and may be incrementally more effective than acetaminophen; selective COX-2 inhibitors have improved gastrointestinal tolerance and might be a better choice than a traditional NSAID in this patient given his gastric symptoms. However, both selective COX-2 inhibitors and traditional NSAIDs promote hypertension and can cause or exacerbate kidney disease; this patient's chronic kidney disease therefore makes them even less desirable as first-line therapy compared with acetaminophen. Other options for pharmacotherapy include local and topical therapy, intra-articular management, tramadol, and, if absolutely necessary, opiates.
Colchicine is an anti-inflammatory agent commonly used in gout and is not recommended for OA therapy.