Prepatellar Bursitis

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

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

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.  

Hemorrhagic bursitis

Hemobursa is a rare cause of acute prepatellar bursitis, except in cases of trauma or anticoagulation.

Frequency

Prepatellar bursitis is the second most common superficial bursitis after olecranon bursitis.

Mortality/Morbidity

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.

Sex

Prepatellar bursitis is more common in males than females.

Age

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]

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)

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]

Physical Therapy

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.

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.

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.

Diclofenac topical (Voltaren Gel, Flector Transdermal Patch, Pennsaid topical solution)

Since prepatellar bursitis is quite superficial, topical NSAIDs such as diclofenac topical gel (Voltaren Gel) can be very effective, with minimal systemic side effects. 

Class Summary

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.

Ibuprofen (Advil, Nuprin, Motrin, Midol)

Drug of choice for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Class Summary

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.

Cephalexin (Keflex, Biocef)

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.

Class Summary

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.

Hydrocortisone (Solu-Cortef, Westcort)

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.