Topics in 607 Primary Care Medicine Olecranon and Prepatellar Bursitis Diagnosis and Treatment JOHN H. McAFEE, MD, and DAVID L. SMITH, MD, Portland "Topics in Primary Care Medicine" presents articles on common diagnostic or therapeutic problems en- countered in primary care practice. Physicians interested in contributing to the series are encouraged to contact the series editors. BERNARD LO, MD STEPHEN J. McPHEE, MD Series' Editors Abursa is a synovial pouch that reduces friction between septic. Nonseptic bursitis is further categorized as idio- adjacent tissues. More than 150 bursae have been iden- pathic, traumatic, or crystal-induced. tified in the human body. Of these, the olecranon and prepa- Features of the Condition tellar bursae are particularly predisposed to infection and inflammation. In this article, we briefly review the anatomy Septic Bursitis of the olecranon and prepatellar bursae and discuss the clin- Septic bursitis usually arises from trautna resulting in ical features and treatment of both septic and nonseptic bur- direct inoculation of the bursal space. Blunt trauma, a skin sitis. wound, or repetitive pressure applied over the knee or elbow may precipitate an infection. Septic bursitis arising from Anatomy and Incidence infection in nearby sites, such as in cases of paronychia, has The olecranon bursa is the only bursa ofthe elbowjoint. It also been reported. In contrast, hematogenous bacterial is positioned subcutaneously on the extensor aspect of the seeding of the bursal sac is rare, probably because of the elbow over the olecranon process of the ulna. The bursal limited vascular supply ofthe bursal tissue. anatomy of the knee is more complex, with four bursae The population at risk for the development of septic bur- recognized over the extensor aspect ofthe kneejoint (Figure sitis includes laborers such as miners, gardeners, carpet 1). The suprapatellar bursa located between the femur and layers, and mechanics, in whom repetitive knee or elbow quadriceps tendon communicates with the knee joint as an trauma is common. Those with a history of alcoholism are extension of that synovial cavity. The deep infrapatellar also prone to septic bursitis due to the repeated traumas they bursa lies between the patellar ligament and proximal tibia receive while intoxicated, coupled with their impaired host and rarely becomes symptomatic. The subcutaneous infra- immunity. Likewise, septic bursitis has developed in some patellar bursa is positioned between the skin and tibial tuber- patients with impaired host defense due to the use ofsystemic osity, and the prepatellar bursa is between the skin and pa- glucocorticoids or to certain medical conditions such as ma- tella. Though anatomically distinct, the prepatellar and sub- lignancy, leukopenia, diabetes mellitus, or chronic renal cutaneous infrapatellar bursae are affected by similar failure. The presence of intrabursal rheumatoid nodules or processes and are collectively referred to as the "prepa- gouty tophi, or a prior history of septic bursitis increases a tellar" bursa. The olecranon and prepatellar bursae are person's risk of bursal infection. Iatrogenic sepsis- may closed spaces that ordinarily do not communicate with the follow an intrabursal steroid injection for nonseptic bursitis. associatedjoint space. The incidence of olecranon and prepatellar bursitis is not Nonseptic Bursitis known. Several articles suggest that septic olecranon and Traumatic and idiopathic bursitis likely have a common prepatellar bursitis account for between 0.01 % and 0.1 % of origin, and idiopathic cases result from unrecognized olec- hospital admissions. The overall incidence of olecranon and ranon or prepatellar trauma. The inciting event may be rela- prepatellar bursitis is probably underestimated by these hos- tively trivial, such as when a person leans on the elbow or pital-based studies because only about 30 % of cases are bumps the knee. The same population predisposed to septic septic, and only patients with the most severe cases of septic bursitis is at risk for the development of traumatic bursitis. bursitis require admission. Crystal-induced bursitis most often occurs in patients with a The approach to diagnosing olecranon and prepatellar history of gout. In one series of 15 patients, approximately bursitis is to broadly classify the condition as septic or non- 40 % of those examined had concurrent acute gouty arthritis (McAfee JH, Smith DL: Olecranon and prepatellar bursitis-Diagnosis and treatment. West J Med 1988 Nov; 149:607-610) From the Division of General Medicine, Ambulatory Care and Medical Service (Drs McAfee and Smith), Section of Arthritis and Rheumatology Disease (Dr Smith), Oregon Health Sciences University School ofMedicine, and the Veterans Administration Medical Center, Portland. Reprint requests to John H. McAfee, MD, VA Outpatient Clinic, PO Box 1036, Portland, OR 97207. 608608 TOISTOPICS IN PMAPRIMARY CARCARE MMEDICINEE at an adjacent or nearby joint. A minor bursal trauma may be a precipitating factor by causing intrabursal crystal shedding. TABLE 1.-Clinical Features of Septic and Nonseptic Olecranon and Prepatellar Bursitis Although seen infrequently, a case ofcalcium pyrophosphate crystal-induced bursitis from localized chondrocalcinosis Forms of Bursitis may produce similar features. Finally, rheumatoid arthritis Traumatic and Clinical Feature Septic idiopathic Crystal-induced may be associated with nonseptic olecranon or prepatellar bursitis. Intrabursal rheumatoid nodules are occasionally History of trauma ...... Common Common Occasional present. Bursal tenderness . Very common Occasional Very common Skin abrasion or wound . Common Occasional Rare Clinical Evaluation Local warmth ....... Common Rare Common Local erythema ....... Common Rare Common On physical examination, the findings of olecranon and Surrounding cellulitis . Common Occasional Rare prepatellar bursitis vary, although several features are usu- Fever .Common Absent Occasional ally present. Localized bursal swelling over the extensor aspect of the elbow or knee is universally seen. Localized other systemic signs of infection do not complicate cases of bursal fluctuance is usually present, with bursal fluid vol- traumatic and idiopathic bursitis. umes ranging from a few drops to 40 ml. An especially The physical findings in patients with crystal-induced important finding is that painless passive range of motion of bursitis reflect an acute inflammatory process. Canoso and the knee or elbowjoint is preserved except at extreme flexion Yood reported 15 cases of acute gouty bursitis. All patients where the swollen bursal compartment may become com- had signs of acute bursal inflammation. Three ofthe patients pressed. Generalized joint swelling, inflammation, and a re- had low-grade fever, and six patients had concurrent gouty stricted range of motion imply that arthritis is present. In arthritis. most cases, an arthrocentesis should be done. Characteristics of Bursal Fluid Septic Bursitis The medical history and physical examination may not Septic bursitis involves the olecranon bursa about four suffice to distinguish septic from nonseptic bursitis (Table 1). times more often than the prepatellar bursa. Bursal tender- An aspirate of fluid from the affected bursa should be exam- ness is present in 90% to 100% of patients, and an abrasion ined routinely to establish the cause of the bursitis and to or laceration over the bursa is present in about 50% of pa- direct therapy. Using aseptic precautions, an 18- or 20-gauge tients. Most patients with septic olecranon or prepatellar needle is introduced into the bursal cavity from a lateral bursitis present with swelling and peribursal cellulitis. Other approach. Aspiration from the extensor side of the knee or findings include fever-40% to 90% of cases-or a mild elbow should be avoided because ofthe higher risk ofchronic "sympathetic" effusion ofthe adjacentjoint. fluid drainage. Unless a history of significant trauma exists, routine knee or Nonseptic Bursitis elbow radiographs are not necessary. A nontender bursal effusion is typical of traumatic and Septic Bursitis idiopathic bursitis, although as many as 45 % ofpatients may Bursal fluid is septic when clinically unmistakable pus is have mild bursal tenderness. About 25% of patients have aspirated. In a few cases, however, the fluid will be straw mild peribursal edema, warmth, and erythema. Fever and colored or serosanguineous. Leukocyte counts of bursal fluid tend to be lower than those for joint synovial fluid. Thus, although the cell count may be more than 200,000 per Al, septic bursitis must be suspected with neutrophil counts as low as 1,500 per fd. The glucose concentration of bursal fluid is often less than 50% of the serum glucose concentra- tion. We routinely measure bursal fluid glucose, although the usefulness of this value for distinguishing septic and non- septic bursitis is not established. Gram's stains of culture- proven septic bursal fluid are negative in about 30% ofcases and cannot be relied on to exclude a diagnosis of septic bur- sitis. Aspirated fluid should be cultured routinely. In most aspi- rates of infected fluids, positive cultures will yield Staphy- lococcus aureus or Staphylococcus epidermidis (90%), or streptococcal species (9%). Rarely is septic bursitis caused by anaerobes, mycobacteria, fungi, Haemophilus influenzae, or other gram-negative organisms. Nonseptic Bursitis Fluid specimen cultures in cases of traumatic and idio- pathic bursitis are sterile