The prepatellar bursa is a superficial bursa with a thin synovial lining located between the skin and the patella. In cadaveric studies, a trilaminar prepatellar bursa was found in 78-93% of people, and a bilaminar bursa was found in 7-22% cases.[1] Normally, the prepatellar bursa does not communicate with the joint space and contains a minimal amount of fluid; when it becomes inflamed, however, there is a marked increase of fluid within its space. It is clinically very important in prepatellar bursitis to differentiate between chronic nonseptic bursitis (NSB) and acute septic bursitis (SB).[2, 3]
Prepatellar bursitis is historically called "housemaid's knee," although it is also known as "coal miner’s knee"[4] and "carpet layer’s knee."[5] In the literature, the earliest reference to the condition and its management occurred in 1861.[6] (See the image below.)
The physician may note any of the following signs and symptoms during physical examination:
Laboratory studies are not usually indicated to diagnose prepatellar bursitis. However, aspiration of prepatellar bursa fluid may be indicated to differentiate NSB from SB. Evaluate the aspirated fluid for white blood cell (WBC) count, protein, lactate, glucose, crystals, and Gram stain results.
Plain radiographs may show soft tissue swelling; however, radiographs are necessary only if other conditions are suggested (eg, fracture and/or dislocation).
Computed tomography (CT) scanning and magnetic resonance imaging (MRI) are reserved for cases that have been difficult to manage (eg, failure of initial treatment for septic prepatellar bursitis).[7, 8] Ultrasonography may be a useful technique for evaluating synovial fluid in the knee.
Conservative Management:
Conservative management consists of protection, rest, ice, compression, and elevation (PRICE); nonsteroidal anti-inflammatory drugs (NSAIDs); and bursal aspiration. Intrabursal steroid injection may be indicated for the treatment of chronic NSB. For acute SB, antibiotic therapy is the key treatment and should be started as soon as infection is suspected after the bursal fluid aspiration. Transient immobilization of the knee in the neutral position with a posterior splint may be needed in cases of acute prepatellar SB.[9]
Physical therapy
After the initial period of rest, the goal of physical therapy is to regain any loss of range of motion (ROM) while increasing the flexibility of the quadriceps and hamstrings. Use of therapeutic modalities can be helpful to assist stretching in this period.
Occupational therapy
The role of the occupational therapist in this scenario is to address modifications of activities in patients diagnosed with prepatellar bursitis secondary to overuse. Emphasize patient education, avoidance of kneeling, and use of kneepads if kneeling is necessary.
Surgical intervention:
Incision and drainage of the prepatellar bursa usually is performed when symptoms of acute SB have not improved significantly within 36-48 hours of antibiotic administration. Surgical removal of the bursa (ie, bursectomy) may be necessary for chronic or recurrent prepatellar bursitis.[10] Arthroscopic or endoscopic excision of the bursa has been reported to have satisfactory results, with less trauma than open excision.[11, 12]
The prepatellar bursa is a flat, round, synovial-lined structure; its main function is to separate the patella from the patellar tendon and skin. This bursa is superficial, suggesting that it is undeveloped at birth. Within the first few months to years of life, the bursa arises from direct pressure and friction. It reduces friction between the skin and the patella and allows maximal range of motion (ROM).
Nonseptic bursitis (NSB) is a sterile inflammation that develops secondary to occupational or athletic trauma, crystal deposition (gout, pseudogout), or systemic disease, such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis,[13] or uremia. Most cases of NSB result from chronic microtrauma caused by repetitive friction. Particularly vulnerable are individuals continually exposed to compressive and sheer forces between the skin and the patella bone, including members of occupational groups whose job requires frequent kneeling or crawling (eg, carpenters, gardeners, roofers) and athletes participating in sports such as ice hockey, volleyball, and wrestling. The inflammatory response causes an overproduction of bursal fluid and subsequent bursal swelling, resulting in NSB.[14, 15]
Septic bursitis (SB) results from infection of the bursal sac, which is frequently caused by skin lesions but can also arise from secondary spread of infection from initial cellulitis into a pretraumatized superficial bursa or, in rare cases, from hematogenous seeding. Infection is commonly caused by bacteria (most often Staphylococcus aureus) but can in rare cases result from fungi.[16] The prepatellar bursa is the bursa most commonly involved in Brucella infection.[17, 18, 19] In addition, tuberculosis of the patella may present as prepatellar bursitis.[20]
Up to 50% of all SB cases occur in immunocompromised patients. Other risk factors include chronic rheumatic inflammatory diseases.
Hemobursa is a rare cause of acute prepatellar bursitis, except in cases of trauma or anticoagulation.
Prepatellar bursitis is the second most common superficial bursitis after olecranon bursitis.
Mortality associated with prepatellar bursitis is rare. Morbidity usually is secondary to pain and limited function.[21] In the case of septic prepatellar bursitis, failure to diagnose in a timely manner may lead to increased morbidity secondary to infectious etiology.
Prepatellar bursitis is more common in males than females.
Prepatellar bursitis can affect all age groups; however, in the pediatric age group, it is likely to be septic and to develop in an immunocompromised host.
The prognosis in prepatellar bursitis is generally good with prompt diagnosis and treatment.
Obtaining the patient's history is important in ascertaining the diagnosis. Common findings reported by the patient with prepatellar bursitis may include the following:
Knee pain
Swelling of the knee
Redness of the knee
Difficulty with ambulation
Inability to kneel on the affected side
Relief of pain with rest
History of repetitive motion
History of occupation requiring excessive kneeling
History of a fall on the knee or blunt trauma to the knee (with presentation of symptoms up to 10 d after the incident)
The physician may note any of the following signs and symptoms during physical examination:
Tenderness of the patella to palpation
Fluctuant edema over the lower pole of the patella
Erythema of the knee
Crepitation of the knee
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]
Any of the following causes may be associated with development of prepatellar bursitis:
Direct trauma (eg, a fall on the patella or direct blow to the knee)
Recurrent minor injuries associated with overuse (eg, repeated kneeling): Superficial bursitis most commonly results from chronic microtrauma
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]
Crystal deposition (eg, gout, pseudogout)
History of inflammatory disease
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]
These include the following:
Cellulitis
Other connective-tissue disorders
Northam and Gaskin reported on a magnetic resonance imaging (MRI) finding of prepatellar fibrosis in three collegiate wrestlers, with the investigators considering the lesion to be of no clinical significance.[25]
Laboratory studies are not usually indicated to diagnose prepatellar bursitis. However, analysis of fluid aspirated from the bursa is important in differentiating septic bursitis (SB) from nonseptic bursitis (NSB). The fluid should be sent for analysis, since the prepatellar bursa is commonly a site of infection. (See the table below.)
Table 1. Characteristics of bursal fluid in patients with septic and nonseptic prepatellar bursitis (Open Table in a new window)
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 |
Evaluate the aspirated fluid for WBC count, protein, lactate, glucose, crystals, and Gram stain results. Typical findings in septic bursitis include the following:
WBC count of 50,000/µL or greater
Elevated protein
Elevated lactate
Decreased glucose
Gram stain results specific to bacteria
In crystal-induced diseases causing bursitis, findings include monosodium urate crystals (gout), calcium pyrophosphate crystals (pseudogout), and cholesterol crystals (rheumatoid arthritis).
Plain radiographs may show soft tissue swelling; however, radiographs are necessary only if other conditions are suggested (eg, fracture and/or dislocation).
CT scanning and MRI are reserved for cases that have been difficult to manage (eg, failure of initial treatment for septic prepatellar bursitis).[7, 8]
Ultrasonography may be a useful technique for evaluating synovial fluid in the knee.
Aspiration of prepatellar bursa fluid may be indicated because sepsis is common. Consider injection of the prepatellar bursa with corticosteroids only when infection has been excluded. Select position of maximal fullness as the site for injection. Complications of injection include, but are not limited to, the following:
Infection
Bleeding
Postinjection inflammation and erythema
Postinjection pain
Tendon rupture
Subcutaneous atrophy
A compression dressing should be worn for 24-36 hours after the procedure, with avoidance of direct pressure to the knee.
Conservative management consists of protection, rest, ice, compression, and elevation (PRICE); nonsteroidal anti-inflammatory drugs (NSAIDs); and bursal aspiration. Intrabursal steroid injection may be indicated for the treatment of chronic NSB. For acute SB, antibiotic therapy is the key treatment and should be started as soon as infection is suspected after the bursal fluid aspiration.
A literature review by Brown et al found that at 1-year follow-up, patients with prepatellar SB who had undergone antibiotic therapy for less than 8 days did not experience a higher recurrence rate than did those who received a longer course of antibiotic treatment.[26]
Transient immobilization of the knee in the neutral position with a posterior splint may be needed in cases of acute prepatellar SB.[9]
After the initial period of rest, the goal of physical therapy is to regain any loss of ROM while increasing the flexibility of the quadriceps and hamstrings. Use of therapeutic modalities can be helpful to assist stretching in this period.
The role of the occupational therapist in this scenario is to address modifications of activities in patients diagnosed with prepatellar bursitis secondary to overuse. Emphasize patient education, avoidance of kneeling, and use of kneepads if kneeling is necessary.
Incision and drainage of the prepatellar bursa usually is performed when symptoms of septic bursitis have not improved significantly within 36-48 hours. Surgical removal of the bursa (ie, bursectomy) may be necessary for chronic or recurrent prepatellar bursitis.[10] Arthroscopic or endoscopic excision of the bursa has more recently been reported to have satisfactory results, with less trauma than open excision.[11, 12]
Using a systematic literature review, Baumbach et al developed a treatment algorithm for olecranon and prepatellar bursitis in which they advised that septic forms of these conditions initially be treated conservatively. They recommended that incision, drainage, or bursectomy be reserved for patients with severe, refractory, or chronic/recurrent disease.[27]
A study by von Dach et al suggested that even in cases of moderate to severe septic prepatellar or olecranon bursitis, it is safe to substitute a one-stage bursectomy with primary closure for a two-stage procedure. The study, which included 168 patients, also found that the median hospital stay was 2 days shorter with the one-stage approach than with the two-stage operation.[28] A study by Uçkay et al concluded that for adults with moderate to severe septic bursitis who require inpatient treatment, bursectomy with primary closure in combination with 7 days of antibiotic drug therapy is a safe and effective approach that saves resources.[29]
A study by Meade et al of 27 cases of recalcitrant septic prepatellar or olecranon bursitis indicated that endoscopic bursectomy can effectively treat these conditions. It has been questioned whether, when performed endoscopically, the procedure allows infected tissue to be adequately debrided in bursitis, thus preventing the disease’s recurrence. However, wound healing complications in the study were absent, and there was just one minor recurrence. In addition, hospital stays were reported to be much shorter than have been found in association with more conservative therapy for septic bursitis and in previous case series on endoscopic bursectomy.[30]
Similarly, the aforementioned literature review by Brown and colleagues indicated that in patients with either septic or nonseptic prepatellar bursitis, endoscopic and open bursectomy are equally effective. At 1-year follow-up, the rate of recurrence did not differ between the two techniques. The investigators also reported that at 1-year post surgery, 80% of patients who underwent endoscopic bursectomy were pain free.[26]
Initiate early orthopedic surgery consultation for severe septic prepatellar bursitis that fails to improve within 36-48 hours and requires incision and drainage. Orthopedic surgery consultation should also be requested in recurrent and/or chronic prepatellar bursitis that does not respond to conservative treatment.
Initiate infectious disease consultation within 36-48 hours in septic prepatellar bursitis that is unresponsive to treatment.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Since prepatellar bursitis is quite superficial, topical NSAIDs such as diclofenac topical gel (Voltaren Gel) can be very effective, with minimal systemic side effects.
NSAIDs are the drugs of choice for mild to moderate pain. They work by decreasing prostaglandin synthesis, thereby reducing inflammation. Ibuprofen commonly is used; however, alternatives are available, such as naproxen and ketoprofen. Use of a particular NSAID usually is secondary to physician and patient experience.
Drug of choice for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.
Antibiotics should be started if septic prepatellar bursitis is suspected or documented after aspiration of bursal fluid for Gram stain and culture. An initial antibiotic can be selected based on a common pathogen (Staphylococcus aureus) and Gram stain results. In some cases of severe inflammation and in immunocompromised individuals, intravenous (IV) antibiotics may be required.
Patients with high risk for methicillin-resistant S aureus (MRSA) infection should receive empiric therapy with an antimicrobial agent that has activity against MRSA, such as IV vancomycin or daptomycin (in cases of severe inflammation) or oral clindamycin, doxycycline, or trimethoprim-sulfamethoxazole (in mild cases).[31]
In a retrospective study of 82 patients treated for severe septic bursitis (in most cases, prepatellar bursitis), Martinez-Taboada et al investigated the effectiveness of antibiotic therapy using cloxacillin, either alone or in combination with another antibiotic.[32] The authors concluded that if extensive cellulites are not present, cloxacillin may by itself be sufficient to treat severe septic bursitis. In particularly severe cases, however, they found that cloxacillin administered in combination with gentamicin appears to be a better treatment choice.
First-generation cephalosporin arrests bacterial growth by inhibiting bacterial cell wall synthesis. Bactericidal activity against rapidly growing organisms. Primary activity against skin flora; used for skin infections or prophylaxis in minor procedures.
Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli. Many injectable corticosteroids are available. Selection usually is physician directed.
Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Conservative care usually is effective for treatment of prepatellar bursitis. Common treatment recommendations may include the following:
Rest
Ice until swelling subsides, then may use ice or heat
Aspiration when necessary
Injection (if no evidence of infection)
Elevation of the affected leg when possible
Anti-inflammatory medications
Antibiotics if indicated because of infection
Assistive device for ambulation if necessary
Inpatient care may be necessary in septic prepatellar bursitis, and the patient may require administration of IV antibiotics.
See the list below:
Avoidance of kneeling
Occupational modifications (use of knee pads)
Prognosis is excellent with definitive treatment.
Stress to the patient the importance of avoiding prolonged or repetitive kneeling, along with making the appropriate occupational modifications.
Overview
What is prepatellar bursitis (housemaid's knee)?
What is included in the workup of prepatellar bursitis (housemaid's knee)?
How is prepatellar bursitis (housemaid's knee) treated?
What is the pathophysiology of prepatellar bursitis (housemaid's knee)?
What is the pathophysiology of nonseptic prepatellar bursitis (housemaid's knee)?
What is the pathophysiology of septic prepatellar bursitis (housemaid's knee)?
What is the pathophysiology of hemorrhagic prepatellar bursitis (housemaid's knee)?
What is the prevalence of prepatellar bursitis (housemaid's knee)?
What is the mortality and morbidity associated with prepatellar bursitis (housemaid's knee)?
What are the sexual predilections of prepatellar bursitis (housemaid's knee)?
Which age groups have the highest prevalence of prepatellar bursitis (housemaid's knee)?
What is the prognosis of prepatellar bursitis (housemaid's knee)?
Presentation
Which clinical history findings are characteristic of prepatellar bursitis (housemaid's knee)?
Which physical findings are characteristic of prepatellar bursitis (housemaid's knee)?
What causes prepatellar bursitis (housemaid's knee)?
DDX
What are the differential diagnoses for Prepatellar Bursitis?
Workup
What is the role of lab tests in the workup of prepatellar bursitis (housemaid's knee)?
What is the role of imaging studies in the workup of prepatellar bursitis (housemaid's knee)?
What is the role of injection in the workup of prepatellar bursitis (housemaid's knee)?
Treatment
What is the role of surgery in the treatment of prepatellar bursitis (housemaid's knee)?
Medications
What is the role of medications in the treatment of prepatellar bursitis (housemaid's knee)?
Which medications in the drug class Antibiotics are used in the treatment of Prepatellar Bursitis?
Follow-up
What is included in conservative treatment of prepatellar bursitis (housemaid's knee)?
When is inpatient care indicated for the treatment of prepatellar bursitis (housemaid's knee)?
How is prepatellar bursitis (housemaid's knee) prevented?
What is the prognosis of prepatellar bursitis (housemaid's knee)?
What is included in patient education about prepatellar bursitis (housemaid's knee)?