Arthroscopic Resection of a Chondroma of the Hoffa Fat Pad: Case Report and Review of Literature ()
Subject Areas: Orthopedics, Surgery & Surgical Specialties
1. Introduction
Hoffa’s disease is an intrinsic pathology of infra-patellar fat pad. It was described for the first time by Albert Hoffa in 1904 and defined as an acute or chronic inflammation of the infra-patellar fat. It involves anterior pain below the patella as main symptom with often a sensation of knee instability. Recurrent episodes of hydrarthrosis are reported especially in chronic cases.
The test of Hoffa is considered positive when the patient complains a pain or apprehension when the examiner presses by his two thumbs on the knee along both edges of the patellar tendon during passage from flexion to extension.
Chondroma of Hoffa seems to be the end-stage of this disease. It’s considered as rare mild cartilaginous tumors. The etiology of this lesion is not well known, but it results probably from repeated traumas responsible for metaplasia of extra-synovial mesenchymatous cells.
2. Case Report
A 40-year-old man complained of pain in his right knee earlier with a feeling of knee instability evolving for 1 year following an occupational accident with a twisting mechanism without changing the range of motion and absence of visible or palpable mass. He received an MRI that objectified a well individualized chondroma of Hoffa without meniscal or ligament lesion associated (Figure 1).
The first arthroscopic exploration revealed several fragments squamous pearly white of cartilaginous aspect filling the joint cavity and removing probably from the chondroma (Figure 2).
After washing aspiration we performed complete resection of chondroma under arthroscopic control after extension of arthroscopic portal. The tissue removed was white-tan, shiny, cartilaginous material. The mass measured 4 × 2 × 2 cm (Figure 3 and Figure 4).
The resection was easy and the chondroma was well bounded. The aspect of the nearby tissue was normal.
The postoperative course was simple and the patient was able to return to work after two weeks. The pathologic anatomical examination of the surgical specimen found in a chondroma.
After a follow-up during six months, the pain decreased significantly and the sensation of instability disappeared.
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Figure 1. MRI image: in patellar tracking intra “Hoffa”.
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Figure 2. Intraoperative arthroscopic aspect of fragments removing from the chondroma.
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Figure 3. Arthroscopic removal of chondroma.
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Figure 4. Macroscopic appearance of chondroma.
3. Discussion
Hoffa’s disease is determined by hyperplasia of the fatty tissue which can sometimes reach the joint and cause expansion of the capsule [1] . Age of onset is between 12 and 75 years old with a mean of 49.4 years old [2] . Although the etiology of this hyperplasia remains obscure, it is almost always associated with a history of knee injuries in young patients leading to the impingement and inflammation of infra-patellar fat [3] - [5] . The chondroma of Hoffa seems to be the final stage of processing adipocytes into chondrocytes and osteoblasts [6] .
Hoffa’s fat pad is intracapsular but extra-synovial. It’s limited by the patella up, the tibia and the infra-patellar purse down, the patellar ligament and the capsule forward and synovial joint back [7] [8] . The clinical picture is most associated earlier pain type of infra-patellar discomfort without modification of articular amplitudes associated to a sensation of instability of the knee especially in up and down stairs. At an advanced stage, a palpable mass more or less visible on clinical examination can be objectified [9] - [11] . The infiltration of corticosteroids in early stage of disease may be offered as a preoperative proposition [12] .
MRI is the gold standard for analyzing fat Hoffa. The most suggestive MRI sign is presence of an important infra-patellar edema of fat body and synovial recess associated with a fibrous area that may contain calcifications. In case of intracapsular chondroma, this examination reveals an heterogeneous mass with a T1 hyposignal and T2 heterogeneous signal. Adjacent bone erosion is possible. Radiography has an interest especially during ossified stages [13] [14] .
4. Conclusion
Conservative treatment is proposed first at all and consists of a strengthening of the quadriceps associated with an anti-inflammatory therapy. Infiltration of corticosteroids in Hoffa fat can also be suggested. Arthroscopic resection remains the treatment of choice in case of failure of conservative treatment.
NOTES
*Corresponding author.