History
Obtaining the patient's history is important in ascertaining the diagnosis. Common findings reported by the patient with prepatellar bursitis may include the following:
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Knee pain
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Swelling of the knee
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Redness of the knee
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Difficulty with ambulation
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Inability to kneel on the affected side
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Relief of pain with rest
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History of repetitive motion
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History of occupation requiring excessive kneeling
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History of a fall on the knee or blunt trauma to the knee (with presentation of symptoms up to 10 d after the incident)
Physical
The physician may note any of the following signs and symptoms during physical examination:
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Tenderness of the patella to palpation
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Fluctuant edema over the lower pole of the patella
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Erythema of the knee
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Crepitation of the knee
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Decreased knee flexion secondary to pain
Although a local skin lesion or fever can be a sign of septicity in bursitis, a study by Tuff and Chrobak, indicated that this is not always the case. In the study, involving two patients with septic olecranon bursitis and one with septic prepatellar bursitis (all adult hockey players), no local skin lesions were found, and only one patient, with olecranon bursitis, suffered from fever. The investigators stated, therefore, that clinicians should have a high index of suspicion for septicity in acute bursitis even when local skin lesions and fever are absent. [22]
Causes
Any of the following causes may be associated with development of prepatellar bursitis:
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Direct trauma (eg, a fall on the patella or direct blow to the knee)
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Recurrent minor injuries associated with overuse (eg, repeated kneeling): Superficial bursitis most commonly results from chronic microtrauma
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Septic or pyogenic process
Infection common from Staphylococcus aureus (usually from a break in the skin)
More prevalent in children
Can be mistaken for pyogenic arthritis
Fungal bursitis caused by Prototheca wickerhamii; usually occurs in immunocompromised patients (rarely reported in immunocomptent individuals) [23]
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Crystal deposition (eg, gout, pseudogout)
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History of inflammatory disease
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Occupation
Carpet layer
Coal miner
Roofer
Plumber
Homemaker (housemaid's knee)
Krishna et al reported on the case of a male patient, aged 25 years, with postpolio residual paralysis, who developed massive prepatellar bursitis as a result of ambulating on his knees. The patient, who was obese and had scoliosis (convexity to the right side), had swelling on the anterior portion of the right knee measuring 20 x 10 x 8 cm. [24]
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Prepatellar bursa in normal (left) and inflamed (right) state; trilaminar form.
Tables
Characteristic |
Septic bursitis (SB) |
Nonseptic bursitis (NSB) |
Appearance |
Purulent |
Serosanguineous, straw colored, or bloody |
White blood cell count per µL |
1500-300,000; mean 75,000 |
50-10,000; usually < 3000 |
Differential count |
Polymorphonuclear (PMN) cells |
Predominantly mononuclear cells |
Bursal fluid–to–serum glucose ratio |
< 50% |
>50% |
Gram stain |
Positive in 70% |
Negative |
Culture |
Positive |
Negative |
