Prepatellar Bursitis


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Definition/ Description 

In general, a bursa is a closed pocket filled with a liquor which ensures there is less friction between body parts. The prepatellar bursa is located under the skin and occurs in most people. Many different aetiologies have been proposed as the cause of prepatellar bursitis. The inflammation of a bursa is called bursitis. This inflammation can take form by either an infectious nature (30%) or a non-infectious nature (70%). The infectious prepatellar bursitis is caused by a bacterial invasion from the immediately overlying skin. Chronic inflammation of prepatellar bursa after repetitive minor trauma is called ‘housemaid’s knee’. It can be seen in the those who have to kneel very often, such as carpet layers and housemaids. Also a fall directly on the patella, an acute trauma, may cause patellar bursitis. Other causes of the prepatellar bursitis are infections or low-grade inflammatory conditions, such as gout, syphilis, tuberculosis or rheumatoid arthritis.

Clinically Relevant Anatomy

The kneecap is a triangular shaped bone in front of the knee. It moves up and down in the groove of the femur when you bend and straighten your knee. The patellar tendon is a thick structure that connects the bottom of the patella with the tibia. The upper part of the patella is connected to the quadriceps, who provokes the knee extension and moves the patella upwards. A bursa is a small with fluid filled sac that decreases friction between two tissues. This can be between skin and a tendon or between bony structures. Most of the time bursae are located around large joints such as the knee, hip, elbow and shoulder.

There are a lot of bursae around the knee that we can divide into two groups: those that are lying around the patella and those that occurs elsewhere. The suprapatellar bursa, the superficial, deep infrapatellar bursae and prepatellar bursa are situated around the patella. Bursae that are not close to the patella are for example the pes anserinus bursa and the iliotibial bursa.  

The suprapatellar bursa is located between the tendon of the quadriceps and the femur. It interacts with the knee joint as an extension of that synovial cavity. The deep infrapatellar bursa lies between the ligament of the patella and the tibia plateau and is rarely symptomatic. The subcutaneous infrapatellar bursa lies between the overlying subcutaneous tissue and tibial tuberosity and the prepatellar bursa lies between the overlying subcutaneous tissue and the patella. Anatomically, the prepatellar and subcutaneous infrapatellar bursae are mostly affected by the same processes and are collectively referred as the ‘prepatellar bursa’.

Epidemiology/Etiology

When a bursa is infected it can probably cause pain, fever, tenderness and an elevated amount of white blood cells. This can be a septic or a non-septic bursitis and it is not always easy to distinguish those two on clinical grounds or by diagnostic tests.

Typically for a septic prepatellar bursitis is a break in the skin near the bursa, which leads to swelling and pain around this area. This happens when a bacteria (for example S. Aureus, 80% of the cases) have passed across the soft tissues from a break in the skin and begins to multiply within the bursa. Also constant friction between the skin and the patella, pressure and impacts of the anterior knee (falling directly onto the patella)  can be a cause of this condition. By an impact the damaged blood vessels in the knee results in inflammation and swelling of the bursa. Actually a bacterial seeding of the bursal sac caused by a hematoma is rare, because of the limited vascular supply of the bursal tissue.

Prepatellar bursitis is also called housemaid knee or carpenters knee. The prepatellar bursitis is an ailment that often occurs in specific jobs which involve a position where they sit on their knees like miners, gardeners, carpet layers and mechanics.This chronic prepatellar bursitis is caused by repeated blows or friction on the knee. The prepatellar bursitis affects men more often than women and it can emerge at all ages. 80% of the people with prepatellar bursitis are men aged between 40 – 60 years. 1/3 of the prepatellar bursitis are septic and 2/3 are non-septic.  An infectious prepatellar bursitis emerges more often with children than grown-ups.

Prepatellar bursitis occurs often, with at least an annual incidence of 10/100 000. The incidence of prepatellar bursa is probably underestimated because most of the case are non-septic and only patients with the most severe cases of prepatellar bursitis requires admission in the hospital. 

We can conclude that prepatellar bursitis can occur after an acute trauma like falling directly on the patella, an infection or low-grade inflammatory conditions like arthritis, gout, syphilis and tuberculosis. 

Characteristics/Clinical Presentation

The two most common symptoms are pain and swelling.  The bursa can occur an hour after a blow and can build up over weeks when there is daily friction on the knee. The pain is often present during movements, in rest and at night. The pain is shallow but there are moments where a very sharp, stinging pain can arise. On top of these two symptoms irritation and sensitivity surrounding the patella can occur. When the bursitis is infectious because of the bacterial infection of the bursa, the pains can be associated with fever. A bursitis isn’t often connected with a change in the ‘range of motion’. The flexion and extension of the knee can in some serious cases be gravely reduced, because the bursal compartment becomes compressed and this causes pain during these movements. An especially important finding is that passive range of motion of the knee feels painless. The knee will feel painful while bending and stretching.
The bursal fluid is septic when pus is aspirated. The number of leukocytes is mostly lower than those for joint synovium and the neutrophil counts are as low as 1500 per fd.
Nonseptic bursitis fluid of the bursa has typically a low vicosity and ranges from straw colored to bloody.

Differential Diagnosis

Prepatellar bursitis is often confused with other causes of knee pain:
• Medial Collateral and Lateral Collateral Ligament Injury
• Osteoarthritis: an inflammation of the bone and knee joint.
• Pes Anserinus, Bursitis: pain is located on de proximal medial aspect of the knee.
• Posterior Cruciate Ligament Injury:
• Rheumatoid Arthritis: is a systematic autoimmune inflammatory disease and causes persistent inflammation of synovial tissue.
• Patellar tendon rupture
• Chondromalacia patella , Patellofemoral pain: common cause of anterior knee pain and difficult to examine an treat.

Diagnostic Procedures

A bursitis can be established through anamnesis and a physical examination. The therapist has to try and determine the origin and the course of the pain during the anamnesis. It’s imperative that the therapist can exclude an infection during the diagnosis. In doubt of an infection, the therapist will extract some fluids out of the knee and send this substance to a laboratory for further examination. When the patella is under pressure the patient will feel a stinging pain in this exact spot. The pain is connected with local swelling. It is also imperative to check if there is a reduction in mobility. The testing of the patella is often not possible with patients who carry a serious prepatellar bursitis, because the tissue around the patella is very sensitive.

To make sure that the injury is a prepatellar bursitis, that the patella isn’t broken or that there aren’t any ruptures in the tendons in and around the knee, an x-ray, MRI and CAT-scan can be taken. A arthogram, aspiration or blood test can be used to rule out other injuries.

Outcome Measures

• Physical examinations
• MRI, ultrasound
• NIOSH Questionnaire: lifetime prevalence of seven knee pathologies (bursitis, arthritis, knee taps, infections, fractured patella, surgery,.)
• NHANES Questionnaires: prevalence of ten knee symptons
• KOOS Questionnaire : consists of 5 subscales (Pain, other symptoms, Function in daily living ADL, Function in sport and recreation and knee related quality of life). Each questions gets a score from 0 to 4 and a normalized score is calculated for each subscale (100 = no symptoms and 0 = extreme symptoms).
• Visual analogue scale (VAS): to measure pain intensity
• Anterior Knee Pain Scale: to measure the functions

Examination

For doctors and therapists it is usually obvious to diagnose prepatellar bursitis from the physical examination. The patients will also be asked questions about their history and they have to describe the onset of symptoms, the pattern of knee pain and swelling and how the symptoms affect their lifestyle. All of this is important for the diagnose and treatment.

For the physical examination, the doctor will examine the patient’s knee joint, pain, range of motion, tenderness and will look for swelling. For the range of motion, a bursitis doesn’t normally affect joint movement, though in some cases the swollen bursa can make it difficult to completely flex of straighten the knee. The temperature of the skin might be warmer than another place and could be pink or red. It’s also possible that the patient could have a fever or chills or feeling sick. This can be a sign of a septic bursitis. Immediately medical care is necessary to make sure the infection does not spread.

In cases of immediately swelling of the knee after a fall or other injury to the kneecap, the doctor has to be sure the kneecap isn’t fractured. X-rays have to be taken. Chronic bursitis is normally easy to diagnose without any other significant tests. Also MRI’s and ultrasounds can be taken, but it’s only used if the doctor isn’t sure whether the symptoms are caused by knee bursitis or another condition.
If it is uncertain whether or not the bursa is infected, an arthrocentesis can be done. It is typically done for three reasons: necessary information is needed to make a diagnose, to relieve the pressure in the joint and will help alleviate the pain and excess fluid also needs to be removed before a therapeutic injection is given. 

 
When there is a limited range of motion or swells, a doctor may recommend using a needle and syringe to remove the fluid from the joint. This fluid can be send to labs for testing whether or not the bursa is infected.
Common tests for infection are gram stain, white blood cell count (an elevated number of white blood cells in the synovial fluid indicates infection) and glucose levels tests (when the levels are significantly lower than normal it may indicate an infection). Gram stain is used to determine if there are certain troublesome bacteria present. Not all bacteria’s can be identified. Even when the test comes back negative, a septic bursitis cannot be completely ruled out.

Medical Management

A bursitis prepatellaris should in general heal all by itself. In the first place an anti-inflammatory medication is often used. After that the doctor will advise to decrease physical activity to avoid any kind of overload. It is often suggested to use theR.I.C.E regime  in the first 72 hours after the injury or when the first signs of inflammation appear. In case that rest isn’t sufficient for full rehabilitation, the doctor may send the patient on to a physiotherapist (look at Physical Therapy Management).
In case the physiotherapist’ therapy doesn’t help, other measures must be taken.

- Infiltration.
This part of the therapy is not done by the physiotherapist himself, but he has to know the existence of it. In other serious cases the patient will have to undergo infiltration. In order to do this de doctor will inject corticosteroids into the inflamed bursa of the patient. After this infiltration has taken place, a solid pressure bandage must be placed and it is suggested that the patient rests for 48 hours.

- Operation.
In case of a chronic bursitis prepatellaris the doctor will suggest an operation. This only happens occasionally in heavy cases. Either the bursa shall be removed or the tendon will be extended during the operation. The extension of the tendon will reduce the pressure that is placed on the bursa, which in turn will reduce the patient’s pain. The regular duration of the operation is 18 minutes. After the operation, the process of healing shall take from 6 to 8 weeks. Skin problems are the most typical complication of surgical treatment for prepatellar bursitis.Over time a new bursa will grow back.

When conservative treatments have failed as treatment for post-traumatic prepatellar bursitis, outpatient arthroscopic bursectomy under local anaesthesia is an effective procedure. The treatment for prepatellar bursitis depends primarily on the cause of the bursitis and secondarily on the pathological change in the bursa. A surgical procedure is in most cases not required, but if needed, the surgical procedures involved are (1) aspiration and irrigation with a suitable drug, (2) incision and drainage in cases of acute suppurative bursitis, and (3) excision of chronically infected and thickened bursa. For the last category of patients, we customarily make a transverse incision at the anterior knee area under local or general anaesthesia, which results in admission to the hospital and leaves poor cosmetic results. The resultant skin problems cause suffering in some of the cases. This study proposes an out-patient arthroscopic method under local anaesthesia aiming at a better cosmetic appearance and a cost saving for the treatment of chronic prepatellar bursitis. We make an assumption that the results of endoscopic approach would be better than those who got the conventional technique.

-Operative technique
The patients are placed in a supine position and the tourniquet will be routinely applied on the thigh and not inflated until necessary. The skin will be prepared in an aseptic manner over the whole lower extremity. A solution will be infiltrated at the portal site and into the cavity, respectively a 1% xylocaine solution with a 1:100,000 epinephrine. For monitoring a 2.7-mm, 30-degree endoscope will be used and a 2.7-motorised shaver to remove thickened synovium. Two or three 2mm portals will be made; an anterior medial portal and anterior lateral portal are routinely used and if necessary a superior lateral portal. To make a 2mm incision for each portal, a no. 11 scalpel will be used. After this, the trochar will be inserted into the cavity and the other instruments will follow. The bursa cavity and synovial thickening are directly visible by the endoscopy. The motorized shaver inserts through the other portal and total synovectomy including the bursa will be performed until all the pathological lesions are removed. When all the procedures are completed, the portals will be closed with adhesive tape without any suture. The anterior knee area is dressed with loosely unfolded gauze, padding and bandage is applied.

-Postoperative care
There is no hospitalization needed, patients can go home immediately after the surgery. There is also no need for antibiotics, either before or after the operation. Non-steroidal anti-inflammatory drugs will be given to the patients, also applying ice packing is recommended for the first 48 hours. Also the wounds are not inspected for the first 48 hours. An elastic compression bandage will be applied to the knee in the first week. In the first two weeks, vigorous activity is not allowed. Returning to normal activities is allowed in the third postoperative week.

-Medication:

• Steroid injections
Cortisone injections, often called corticosteroid injections or simply steroid injections. It decreases joint inflammation, including swelling, heat, and redness, and in turn ease joint pain. 

• Corticosteroid injections
Corticosteroid injections may alleviate the symptoms quickly. The corticosteroid injections are effective, but some studies have shown that these injections have been linked with side effect such as pain and skin degeneration. Therefore, corticosteroid injections are mostly kept aside for patients that don’t respond to other treatments.

• Non-steroidal anti-inflammatory drugs, or NSAIDs
To decrease the pain, swelling, and inflammation, patients can ask for a prescription or for over-the-counter anti-inflammatory medications, such as aspirin, ibuprofen, naproxen, and COX-2 inhibitors. Patients should check first with their physician before taking NSAIDs. It can interact with supplements, vitamins, and/or other medications that the patients are taking at the moment.

• Topical medications
Creams, sprays, gels and patches can provide pain relieve when those are directly applied to the skin over the knee. When people want to reduce the gastrointestinal side effects that can be caused by oral medications, tropical medications may be a good choice.
Side effects or negative drug interactions may occur from using tropical medications. When patients have to take new medication, they should always discuss it with their doctor or pharmacist. Certainly read the drug labels and instructions indicated on the box.

Physical Therapy Management

The treatment of a bursitis is comparable with the treatment of an overuse injury. (level of evidence 2a)

The therapist will often begin with soft tissue massages, this is important for the trophicity and better vascularity. This is followed by some mobilisations in flexion; it is the only anatomic position where a movement restriction can occur. This is possible because of the swelling. When the passive mobilisations are done the physiotherapist will give some light exercises to the patient. A nice example of such an exercise is when the patient sits on the edge of the table and lightly lifts and then drops the knee again. As soon as the patient can fulfil the exercises without any pain, the physiotherapist will step on to more specific exercises based on muscle-strengthening en flexibility.
An important exercise is the static contraction of the quadriceps.(level of evidence 5) This should be an exercise that the patient can fulfil at home 1 to 3 times a day. The objective of the rehabilitation is that patient can resume their everyday activities. The patient must push a towel into the table by using his quadriceps. To see if the exercise is working you have to put your fingers on the inner side of the quadriceps, you will feel the muscle tighten during the contraction of the muscle. The patient has to hold his contraction during 5 seconds; the exercise can be repeated 10 times as hard as possible. It is important not to forget this exercise must be pain free. 

Also the stretching of the quadriceps is a good exercise for the patient, it reduces the friction between the skin and the patella tendon. There is less friction when the patella tendon is more flexible. The physiotherapist can also help the patient by using electrotherapy, schooling and giving advice. This advice shall mostly be about how to make the right movements. Ultrasound on the prepatellar bursitis is a treatment that’s not often used.

Besides the Rest, Ice, Compression and Elevation (=RICE) -method (level of evidence 2a) is a common used treatment for prepatellar bursitis. The ‘rest-phase’ consists a short period of immobilization. This period should be limited to the first days after the trauma. Resting will reduce the metabolic demands of the injured tissue and will avoid increased blood flow. The use of ice will cause a decrease of the temperature of the tissues in question, inducing vasoconstriction and a limitation of the bleeding. Also the pain wel decrease because the ice will occur increasing threshold levels in the free nerve endings and at synapses. Don’t put the ice too long on your knee (maximum 20 minutes at a time with an interval of 30-60 minutes). The compression will decrease the intramuscular blood flow to the affected area and will also reduce the swelling. At last there is the elevation. This ensures that the hydrostatic pressure will decrease and it will also reduce the accumulation of interstitial fluid. This part of the Rice-principe also decreases the pressure in local blood vessels and helps to limit the bleeding. However, the effectiveness of this RICE-method has not been proven in any randomized clinical trial.
In some cases there may be an aspiration of the fluid and an infiltration with an anti-inflammatory drug. (level of evidence 2a)

Prevention

In order to prevent a prepatellar bursitis you should avoid injury or an overload of your muscles. It is very important to do an appropriate warm-up and cool down, while playing sports. For example if you play volleyball, it is advisable to wear knee pads. This will prevent falling on the kneecap. Also when you spent a lot of time on your knees is it advisable to wear knee pads. Another important thing to avoid a prepatellar bursitis is to check if the flexibility of the knee and the strength and endurance of the leg mucles stays optimal.

Key Research

• Yu-Chih H, et al. Endoscopic treatment of prepatellar bursitis. Int Orthop 2011; 35(3): 355–358.(2)
• Hurkmans E.J., et al. KNGF-guideline for Physical Therapy in patients with rheumatoid arthritis. 2008; 118 (5): 13-16.(1)

From Web of knowledge

• Infectious olecranon and patellar bursitis: short-course adjuvant antibiotic therapy is not a risk factor for recurrence in adult hospitalized patients http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=2&colname=WOS
  
• Cloxacillin-based therapy in severe septic bursitis: Retrospective study of 82 cases http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=3&colname=WOS
  
• Ossifying Bursitis Praepatellaris of the Knee Joint http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=4&colname=WOS
  
• Hemorrhagic prepatellar bursitis: a rare case report and review of the literature http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=8&colname=WOS
  
• Prepatellar Septic Bursitis: A Case Report of Skin Necrosis Associated With Open Bursectomy http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=7&colname=WOS
  
• Olecranon and prepatellar bursitis - Treating acute, chronic, and inflamed http://apps.isiknowledge.com.ezproxy.vub.ac.be:2048/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S24LCBd8ahiI4bB3hJ7&page=1&doc=30&colname=WOS

Resources

• http://www.drlox.com/knee-pain-v2/knee-bursitis/
• http://www.houstonmethodist.org/orthopedics/where-does-it-hurt/knee/prepatellar-bursitis
• http://www.arthritis-health.com/types/bursitis/knee-prepatellar-bursitis

Clinical Bottom Line

The prepatellar bursa is located under the skin and occurs in most people. When a bursa is inflamed, it's called a bursitis. The inflammation can be of an infectious nature or a non-infectious nature. Many different aetiologies have been proposed as the cause of prepatellar bursitis. Chronic inflammation of prepatellar bursa after repetitive minor trauma is called ‘housemaid’s knee’. It can be seen in the those who have to kneel very often, such as carpet layers and housemaids. Also a fall directly on the patella, an acute trauma, may cause patellar bursitis. Treatment for prepatellar bursitis depends primarily on the cause of the bursitis and secondarily on the pathological change in the bursa. A surgical procedure is in most cases not required, but if needed, the surgical procedures involved are (1) aspiration and irrigation with a suitable drug, (2) incision and drainage in cases of acute suppurative bursitis, and (3) excision of chronically infected and thickened bursa. 

Recent Related Research (from Pubmed)


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• Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm.
• Septic Bursitis in an 8-Year-Old Boy.
• The Morel-Lavallée Lesion as a Rare Differential Diagnosis for Recalcitrant Bursitis of the Knee: Case Report and Literature Review.