Overview of Prepatellar Bursitis

Prepatellar bursitis, colloquially referred to as “housemaid’s knee” or “carpenter’s knee,” is an inflammatory condition of the prepatellar bursa. This fluid-filled sac cushions the area between the patella (kneecap) and the skin. This bursa is particularly susceptible to inflammation due to its superficial location, making it vulnerable to trauma, repetitive kneeling, and prolonged pressure on the knees—hence its association with occupations such as gardening, carpet laying, mining, and mechanics.

The condition can be classified into two main types: infectious (septic) and non-infectious. Non-infectious prepatellar bursitis accounts for most cases (around 70%). It is typically triggered by repetitive mechanical stress, direct trauma, or chronic pressure. Acute injuries such as a direct fall onto the knee or consistent friction from kneeling can inflame the bursa, leading to swelling, pain, and restricted movement. Over time, even minor trauma or repetitive motion can accumulate and manifest as bursitis, underscoring the importance of proper ergonomics and protective measures in high-risk professions. Infectious prepatellar bursitis (30%) occurs when bacteria infiltrate the bursa, leading to septic inflammation. This typically arises from cuts, abrasions, or puncture wounds near the knee that allow pathogens like Staphylococcus aureus to enter and infect the bursa. Septic bursitis presents more severely, often accompanied by fever, increased pain, and noticeable warmth or redness over the affected area. Prompt medical intervention is critical, as untreated septic bursitis can lead to severe complications, including abscess formation or systemic infection.

Anatomy of The Patella

The patella, commonly known as the kneecap, is a sesamoid bone embedded within the quadriceps tendon, playing a pivotal role in knee mechanics. Shaped like an inverted triangle, the patella is located anteriorly to the knee joint and resides within the patellofemoral groove of the femur. Its primary function is to protect the knee joint while enhancing the leverage of the quadriceps muscle, facilitating efficient knee extension. When the knee flexes or extends, the patella glides smoothly within this groove, guided by surrounding structures like the quadriceps tendon, which attaches to the superior aspect of the patella and the patellar tendon. This robust structure connects the inferior pole of the patella to the tibial tuberosity. This configuration allows the patella to act as a fulcrum, amplifying the force generated by the quadriceps muscle group during leg extension. Surrounding the patella are several bursae, which are fluid-filled sacs that reduce friction and cushion the movement of tendons and muscles over bony prominences. 

Bursae around the patella can be categorised into two primary groups. The first group includes the bursae around the patella, such as the suprapatellar bursa, the prepatellar bursa, and the superficial and deep infrapatellar bursae. These bursae are critical in minimising friction between the patella, skin, and surrounding soft tissues. The second group consists of bursae found elsewhere around the knee, such as the pes anserine bursa, located on the medial aspect of the knee, and the iliotibial (IT) bursa, which is associated with the IT band on the lateral side of the knee. These bursae, although not directly connected to the patella, still contribute to the overall functionality and health of the knee joint by ensuring smooth movement of tendons and muscles over adjacent bone structures.

How Common Is Prepatellar Bursitis

Prepatellar bursitis is more prevalent among men than women and typically affects individuals between the ages of 40 and 60. Men account for about 80% of cases within this age group. The condition can arise at any age, but the incidence is higher among men, especially those engaged in occupations or activities that involve prolonged kneeling. About one-third of prepatellar bursitis cases are septic, with infections being more common in children than adults. Non-septic cases make up the remaining two-thirds. The annual incidence of prepatellar bursitis is approximately 10 per 100,000 people, which is likely underestimated. Many cases, especially non-septic ones, may not be reported as only the most severe instances typically require hospitalisation.

What Causes Prepatellar Bursitis

Prepatellar bursitis arises from various mechanical and infectious causes. Direct trauma or repeated impact to the anterior knee, such as frequent falls or constant friction between the skin and the patella, can lead to inflammation of the prepatellar bursa. This results in swelling due to damaged blood vessels. However, infection via hematoma is rare because of limited vascular supply in the bursal tissue. Septic prepatellar bursitis typically occurs when bacteria, most commonly Staphylococcus aureus (80% of cases), infiltrate the bursa through a skin break. Symptoms of an infected bursa may include pain, fever, tenderness, and elevated white blood cells. Additionally, underlying inflammatory diseases such as rheumatoid arthritis or gout may contribute to the development of prepatellar bursitis.

What Are The Symptoms of Prepatellar Bursitis?

Prepatellar bursitis presents various symptoms, primarily characterised by localised pain and swelling at the front of the knee. Swelling is often pronounced and may be accompanied by warmth in the affected area due to inflammation. Pain intensifies with movement, leading to a restricted range of motion (ROM) in the knee joint. In cases where an infection causes bursitis, additional symptoms such as fever and chills may be observed. The infected bursa may also become particularly tender to touch, further complicating mobility.

How Is Prepatellar Bursitis Diagnosed?

Diagnosing prepatellar bursitis requires a thorough assessment involving a clinical history and a physical examination. The history focuses on understanding the onset and progression of symptoms, particularly knee pain swelling, and their impact on daily activities. Physical examination evaluates the knee’s appearance, palpation for warmth, and pain with movement. Imaging studies such as X-rays, MRI, or CT scans may be employed to exclude other conditions like fractures or soft tissue injuries. If infection is suspected or the diagnosis is unclear, arthrocentesis (joint aspiration) is performed to analyse the synovial fluid. This 

procedure serves several purposes:

• Obtaining critical diagnostic information
• Alleviating pressure and pain by draining excess fluid
• Enabling therapeutic injections if needed

Fluid analysis can help confirm or rule out septic bursitis. If a bacterial infection is present, further interventions are guided accordingly. In cases where bursitis coexists with systemic inflammatory diseases like rheumatoid arthritis or gout, additional diagnostic considerations must be made to tailor treatment effectively. Accurate diagnosis is essential for formulating a comprehensive and targeted treatment plan that addresses the local pathology and any underlying contributing factors.

How Is Prepatellar Bursitis Treated?

Treatment for prepatellar bursitis is multifaceted and tailored to the underlying cause and specific pathological changes in the bursa. The primary focus of treatment is to control inflammation, alleviate pain, and promote tissue repair.

• HPL Therapy For Prepatellar Bursitis:

High Power Laser (HPL) Therapy offers a non-invasive approach, utilising focused light energy to penetrate deep tissues. Although specific evidence for bursitis is limited, it’s shown promise in reducing pain and inflammation in other musculoskeletal conditions. The therapy stimulates blood circulation, accelerates the removal of inflammatory mediators, and enhances cellular energy production (ATP) to aid tissue regeneration. This non-invasive modality can be a valuable addition to the overall treatment plan for prepatellar bursitis.

• Shockwave Therapy For Prepatellar Bursitis:

Extracorporeal Shockwave Therapy (ESWT) utilises high-energy acoustic waves to stimulate healing in inflamed tissues. Though more commonly used for conditions like tendinopathy, it has also proven helpful in managing bursitis. The waves create microtrauma within the tissue, promoting the body’s natural healing processes. This can help reduce inflammation, improve tissue regeneration, and relieve pain. Given its effectiveness, ESWT may be a valuable option, especially for chronic or recalcitrant cases of prepatellar bursitis.

• Medications For Prepatellar Bursitis:

Non-steroidal anti-inflammatory drugs (NSAIDs) and topical treatments like creams, sprays, gels, and patches provide localised relief by reducing inflammation and pain when applied directly to the affected area. These topical options may benefit patients who wish to avoid gastrointestinal side effects commonly associated with oral medications. In cases of septic prepatellar bursitis, antibiotics are necessary to combat the infection, addressing the root cause while simultaneously managing symptoms.

The treatment plan should be individualised to ensure optimal recovery and minimise the risk of recurrence.

Physical Therapy and Rehabilitation of Prepatellar Bursitis

Physical therapy and rehabilitation play a crucial role in managing and recovering prepatellar bursitis. The initial approach often involves the RICE method—Rest, Ice, Compression, and Elevation. While common, this method should be applied with caution, especially since there is limited high-level evidence to support its efficacy in randomised clinical trials fully. The rest phase is vital immediately following trauma to reduce the affected tissue’s metabolic demands and prevent further inflammation. However, prolonged immobilisation should be avoided, as it can lead to joint stiffness and muscle weakening. Ice application helps reduce inflammation by causing vasoconstriction. Still, it should be applied cautiously—no longer than 20 minutes, with 30-60 minute intervals between applications. Compression through wraps or braces helps minimise swelling, and elevation can reduce hydrostatic pressure, further decreasing fluid accumulation and promoting blood flow.

Once acute inflammation has subsided, therapeutic exercises become essential. Rehabilitation focuses on restoring the full range of motion and strengthening the muscles that support the knee joint. Quadriceps exercises like static contractions are particularly important for maintaining muscle tone and improving stability. Patients should perform these exercises daily, ensuring that movements remain pain-free. The goal is to reintroduce normal activities while avoiding overloading the joint, which could trigger a recurrence of bursitis.

Incorporating quadriceps stretching is also crucial, as it reduces friction between the skin and the patellar tendon, enhancing flexibility and preventing further irritation. A practitioner may supplement the rehabilitation plan with Laser Therapy to reduce pain and inflammation and educate the patient on protective measures such as knee pads for prolonged kneeling activities.