A 67-year-old female patient presented to our institution with bilateral painless knee swelling. Her previous medical history was unremarkable.
Bilateral knee radiographs demonstrated multiple dense, sharply delineated subcutaneous calcifications in the prepatellar region of both knees (Fig. 1a-e).
The synovial-lined prepatellar bursa is located anterior to the lower half of the patella and does not communicate with the knee joint. Its role is to minimise friction between the patellar tendon, the patella, and the subcutaneous tissue [1, 2]. If inflamed, the condition is called prepatellar bursitis. A mechanical contributing factor is usually involved [3]. The most common causes of prepatellar bursitis are overuse of the joint and chronic trauma due to sports (wrestling, football) or occupational activities with frequent kneeling [2, 4]. In the latter case prepatellar bursitis is also named "housemaid’s knee", referring to the chronic and excessive monotone movements of housemaids that used to scrub floors on their hands and knees, with resulting inflammation and cystic swelling of the prepatellar bursa [2, 4]. Other occupations related to the condition are tile layer, carpet fitter, plumber, and roofer. Calcifications may develop in any chronically inflamed bursa, related to decreased blood circulation in settings of repeated trauma, after haematoma resolution, but also secondary to infection [1].
Typical symptoms of prepatellar bursitis include bilateral localised knee swelling over the patella's lower pole due to bursal fluid accumulation, often recurrent, with fluctuance on clinical examination. Erythema may be present. Discomfort or pain are not typical symptoms [3]. Usually there is no limitation of joint movement [3].
In calcific prepatellar bursitis, radiographs show multiple well-defined, dystrophic calcifications projecting on the prepatellar bursa [1, 2]. There may be surrounding tissue swelling. On MRI, the prepatellar bursa becomes visible when inflamed, with oedematous synovia and fluid accumulation, with low signal intensity on T1-weighted images and a high signal intensity on T2-weighted images [2]. Focal areas of low signal intensity on T1- and T2-weighted MRI images correspond to calcifications or chronic blood degradation products [2]. Based on MRI imaging criteria alone, chronic synovial proliferation with heterogeneous surrounding soft tissue changes may, in rare cases, be difficult to differentiate from malignant tumours such as synovial sarcoma, whose clinical manifestations are different with chronic pain more often involved [2].
Therapeutic options include pharmacotherapy with nonsteroidal anti-inflammatory drugs, local steroid injections, bursal fluid aspiration, ice application, bandages, and rest. Surgical bursectomy is indicated in cases where the knee swelling becomes symptomatic and progressive [5].
In conclusion, calcific prepatellar bursitis is a rare condition associated with chronically repeated kneeling. It has a characteristic imaging appearance on radiographs with bilateral multiple well defined calcifications projecting onto the prepatellar bursae.
Calcific prepatellar bursitis - "housemaid's knee"
Based on the provided anteroposterior (AP) and lateral X-ray images of both knees, multiple calcifications of varying sizes with relatively clear margins are visible in the subcutaneous region anterior to the patella (kneecap), mainly located within the soft tissue in front of the patella. Overall, there is no obvious sign of fracture or bony destruction. The joint spaces do not appear significantly narrowed or widened, and the articular surfaces remain relatively regular. Localized swelling can be observed in the surrounding soft tissues.
In summary, given the location of multiple relatively regular calcifications within the soft tissue anterior to the bilateral patellae, combined with the absence of significant pain beyond swelling, calcific prepatellar bursitis remains the most likely diagnosis.
Considering the patient’s age, symptoms (painless swelling in both knees), history of regular activities (if involving repetitive kneeling or joint strain, this further supports the diagnosis), and the typical calcification pattern on X-ray, the most probable diagnosis is: Calcific Prepatellar Bursitis.
If clinical or laboratory results suggest specific concerns (e.g., infection or tumor), further MRI evaluation or aspiration of bursal fluid for analysis may be required to rule out other conditions.
For bursae with significant fluid accumulation, aspiration under strict aseptic conditions may be performed, possibly combined with local drug injection.
If bursitis is recurrent, unresponsive to conservative management, or calcified lesions are significant and interfere with function, surgical excision of the bursa may be considered.
The goal of rehabilitation is to reduce local irritation, strengthen the muscles around the knee joint, and improve joint range of motion. Below is a concise plan based on the FITT-VP principle:
For older adults, special attention should be paid to bone health and cardiopulmonary status, ensuring exercise intensity is managed appropriately. In cases of osteoporosis or other chronic conditions, rehabilitation under the guidance of a professional therapist or physician is advised.
Disclaimer: This report is a reference analysis based on the currently available information and does not replace in-person medical consultation or professional, individualized diagnostic and treatment recommendations. In case of worsening symptoms or if further evaluation is required, please seek medical attention promptly.
Calcific prepatellar bursitis - "housemaid's knee"
