Calcium-Containing Crystal-Associated Arthropathies in the Elderly
Basic calcium phosphate and CPPD crystals may coexist in synovial fluid. Similar to CPPD, BCP crystal disease is often concurrent with OA and can cause calcification of articular cartilage. Basic calcium phosphate is more common than CPP crystals with occurrence of 30% to 50% in OA synovial fluid.42 Additionally, BCP crystal disease has been linked to increased severity of OA. Basic calcium phosphate crystals in knee joints were found to have radiographically more severe arthritis with larger effusions.44,45 Similarly, BCP crystals in OA synovial fluid correlated with higher Kellgreen-Lawrence grade scores by radiography.42,46
It is currently believed that BCP crystals are continuously formed in the extracellular matrix, and their deposition is actively prevented by PPi present in the matrix.47 Elevated PPi levels, on the other hand, favor the formation of CPP crystals.48 The clinical upshot seems to be that although CPP crystals are almost universally intra-articular and released by chondrocytes, BCD crystals and deposits are more frequently present in soft tissues.
Acute Calcific Tendinitis
Typically, this type of tendinitis involves the shoulder joint and is extra-articular. Common treatments help, including NSAIDs, intra-articular steroids, ice, and rest. In addition, high-energy extracorporeal shock wave therapy has been shown to be effective when used with conscious sedation.49,50 Needling or barbotage in association with lavage and steroid injections also is effective and has occasionally been shown to reduce the size of the calcium deposit as well, often in combination with IV drugs like ethylenediaminetetraacetic acid.51-53
Acute calcific periarthritis of the hand presents similar to gout or pseudogout, affecting the wrist, usually in postmenopausal women.54 Basic calcium phosphate crystals are aspirated from the joint, and periarticular crystals may be subtle. Local steroid injections are beneficial.Milwaukee shoulder syndrome is an arthropathy associated with BCP crystals in the joint fluid and results in extensive destruction of shoulder articular cartilage and surrounding tissues. It is commonly bilateral and occurs in elderly women more often than it does in men.55 Aspiration of the shoulder joint typically reveals a serosanginous fluid. Fluid samples can be assessed for hydroxyapatite crystals by staining with alizarin red dye, which produces a characteristic “halo” or orange-red stain by light microscopy.43 Surgical treatment of Milwaukee shoulder syndrome is difficult due to increased age of the population affected and the severity of the shoulder destruction. Usually a conservative approach of analgesics, recurrent shoulder aspirations, and steroid injections is the best treatment option.
Conclusions
Calcium-containing crystal-associated arthropathies are a complex array of entities that target the veteran elderly population with increasing frequency. Challenges still remain in the diagnosis, crystal identification, and treatment due to coexisting comorbid conditions and polypharmacy commonly seen in veterans. Overall morbidity associated with calcium-containing crystal-associated arthropathies and the coexisting osteoarthritis is great, and focused identification of the disease process with tailored treatment can achieve the goal of decreasing symptoms and improving quality of life.
Acknowledgements
This work was supported by grant P20GM104937 (A.M.R.).
