The greater trochanter of the femur is located superficially and is prone to chronic trauma, with abundant local cancellous bone, making subcutaneous nodules of the greater trochanter relatively common, accounting for 1.59% of all bone and joint subcutaneous nodules in the body. They are most frequently seen in young adults aged 20 to 40, while those under 10 years old are rare.

bubble_chart Pathological Changes

1. The greater trochanter is formed by an independent ossification center, which appears at the age of 4 and fuses with the femur at the age of 18.

The greater trochanter is located at the junction of the femoral neck and the femoral shaft. Most of the gluteal muscles insert into the greater trochanter. The gluteus minimus inserts into the rough anterior surface of the greater trochanter, the gluteus medius inserts into the lateral surface of the greater trochanter, and the piriformis inserts into the top of the greater trochanter. The trochanteric fossa contains the obturator externus, while the medial side has attachments of the obturator internus and the superior and inferior gemelli muscles.

The main bursae of the greater trochanter include: the trochanteric bursa of the gluteus maximus, located between the gluteus maximus and the greater trochanter; the gluteofemoral bursa, situated between the lower edge of the gluteus maximus and the fascia of the vastus lateralis; and the bursa of the gluteus medius, found between the tendons of the gluteus medius and minimus and the superolateral part of the greater trochanter.

2. Subcutaneous nodes of the greater trochanter are divided into osseous and bursal types. Some believe that osseous subcutaneous nodes are primary, while bursal types are secondary. An opposing view holds that primary bursal subcutaneous nodes later involve the greater trochanter of the femur. Others argue that the majority of cases originate in the bone, with a minority originating in the bursa. Guo Juling's analysis of 97 cases showed 63 osseous types and 22 bursal types, while data from Leningrad's 137 cases reported 125 osseous types and 12 bursal types, supporting this point.

Among the three main bursae of the greater trochanter, subcutaneous nodes of the trochanteric bursa of the gluteus maximus are relatively more frequent. In the early stages of the disease, the synovial membrane becomes congested, swollen, and produces excess fluid; in advanced stages, the bursal wall thickens, with a rough inner surface covered by dark red granulation or necrotic tissue, often containing caseous material or pus. If the bursa ruptures, the pus may spread to surrounding tissues or penetrate the skin, forming a sinus.

Pus from subcutaneous nodes of the greater trochanter accumulates between the fascia lata and the vastus lateralis muscle. Due to gravity, multiple abscesses may extend to the ipsilateral knee joint. Lesions of the greater trochanter can form abscesses between the gluteus medius, minimus, and the hip joint capsule, sometimes rupturing into the hip joint and affecting it.

Central osseous subcutaneous nodes of the greater trochanter may expand along the femoral neck and head, breaking through the cortical bone and entering the hip joint. During the debridement of greater trochanter subcutaneous nodes, injury to the hip joint capsule or invasion of the hip joint by the lesion may occur.

It is noteworthy that subcutaneous nodes or multiple abscesses from the thoracolumbar, lumbar, lumbosacral spine, or sacroiliac joint may track to the greater trochanter of the femur, leading to secondary subcutaneous node lesions. Therefore, subcutaneous nodes of the greater trochanter should be thoroughly investigated for possible connections with the aforementioned conditions.

The greater trochanter subcutaneous node is commonly seen in young adults. Systemic and local symptoms are usually mild, with local pain often worsening during walking or passive adduction of the limb. The patient cannot lie on the affected side and exhibits grade I limping while walking. The affected limb is in grade I abduction and external rotation, with the hip joint typically flexed at 30°–40°. Movement of the affected hip joint is usually unimpaired, and heel percussion does not cause hip pain. Local swelling, abscess, or sinus is often observed.

bubble_chart Auxiliary Examination

X-ray imaging: Central-type subcutaneous nodules show sequestra, which form cavities after absorption, while marginal-type subcutaneous nodules are primarily characterized by osteolytic destruction. Bursal-type subcutaneous nodules only exhibit soft tissue swelling and localized bone decalcification.

bubble_chart Diagnosis

The diagnosis of a subcutaneous node in the greater trochanteric bursa should be differentiated from the following conditions:

1. Multiple abscesses

Pay attention to examining whether there are subcutaneous node lesions in the thoracic vertebrae, lumbosacral region, and sacroiliac joints. Abscesses or bursal lesions in the greater trochanter should exclude multiple abscesses from the aforementioned conditions. During surgery, it should be determined whether the abscess originates from the pelvic direction. If necessary, X-ray imaging of the thoracolumbar spine or sacroiliac joints should be performed to confirm the diagnosis.

2. Non-specific bursitis

The aspirate is mostly light yellow fluid, and routine bacterial culture is negative.

1. For elderly patients with small abscesses, non-surgical treatment is an option. A rational chemotherapy regimen combined with local aspiration and medication injection can achieve a cure.

2. If the lesion contains extensive necrotic bone or is accompanied by a persistent sinus tract, surgical debridement may be performed.

**Debridement Procedure**

1. **Anesthesia**: General anesthesia or epidural anesthesia.

2. **Positioning**: Lateral decubitus position with the affected side upward. The patient is slightly elevated and abducted to relax the iliotibial tract and fascia lata, facilitating exposure of the lesion.

3. **Incision**: A lateral curved incision over the greater trochanter. For multiple cold abscesses in the lower thigh, an additional small incision may be made.

Along the incision, the deep fascia and tensor fasciae latae are incised and retracted anteriorly, while the gluteus maximus is retracted posteriorly. To fully expose the lesion above the greater trochanter, partial detachment of the gluteus medius and minimus may be performed, and the vastus lateralis is subperiosteally stripped and retracted to reveal the inferior aspect of the lesion. A thorough exploration is conducted to identify the affected bursa, noting its color, size, extent, and any adjacent bone involvement. Conversely, when examining the bony lesion of the greater trochanter, attention should be paid to whether the bursa is affected. If a cold abscess is present, its extent and any communication with the pelvic cavity should be noted.

4. **Debridement**: The diseased bursa is completely excised, and the bony lesion is curetted, avoiding excessive bone removal to prevent postoperative involvement of the hip joint. After irrigation, the iliotibial tract and the gluteus maximus tendon are sutured, followed by layered closure of the incision.

If a sinus tract is present preoperatively, a drainage tube may be placed and removed 48–72 hours postoperatively.

bubble_chart Differentiation

1. Bone metastatic cancer Patients are typically aged 40-50 years, generally in poor condition. The greater trochanter is a common site for bone metastatic cancer. X-ray films show osteolytic destruction, sometimes with pathological fracture.

2. Primary bone tumors For example, giant cell tumor of bone, etc.

3. Wind-dampness-like greater trochanteritis Mostly bilateral, with slight local swelling and tenderness, no abscess formation. X-ray films show irregular edges, densification, or small cystic changes in the greater trochanter.

4. Chronic bone abscess Commonly seen in children and young adults, lesions often occur at the junction below the greater trochanter and the upper femur. X-ray films may show localized osteolytic destruction, mostly without sequestrum. The surrounding bone is dense, with possible grade I periosteal reaction. {|103|}