| Objective: The infrapatellar fat pad(IFP), also known as Hoffa’s fat pad, is an intracapsular and extrasynovial structure that fills the anterior knee compartment. Hoffa(1904) first described the syndrome of impingement of the infrapatellar fat pad. IFP is richly vascularized and innervated. Though the precise function of the IFP is unknown, studies have shown that it may play a role in the biomechanics of the knee or act as a store for reparative cells after injury. Lesions or mass-like abnormalities rarely occur within the IFP, but can act as potent sources of anterior knee pain, with rich nociceptive innervation in the central and lateral portions of the IFP and in the surrounding synovium.With the different pathological source, there are many types, different character, different size, different imaging features, but the symptoms are often similar. Clinically, it was easy to get misdiagnosis and missed diagnosis. Foreigners reported various series of IFP tumor treated by open excision. Nowadays, the therapeutic trend for such lesions is arthroscopic excision. Technological advances throughout the 20 th century enabled an increase in arthroscopic knee surgery, including arthroscopic debridement for IFP tumour or tumour-like lesions. With clinical understanding of the diagnosis, treatment of the disease, we can read more and more literature on arthroscopic resection of the IFP tumours, but mostly case reports. That were lack of convincible evidence, and it was seldom reported in our country.The object of this study was to report a group of benign tumours in the infrapatellar fat pad treated with arthroscopic resection. By analyzed the clinical presentation, histological type, and treatment, we present our suggested management in tumours of IFP.Methods: We performed a retrospective review of our prospectively collected cases of IFP tumours underwent arthroscopic resection and were followed for a mean duration of 35 months(nineteen to 78). The gender, age at presentation, history of trauma, clinical features, histological type, radiological scans and follow-up were recorded. Clinical outcomes were assessed with the Lysholm score. Descriptive summary statistics included means and frequencies. In order to investigate the effect on clinical outcomes, paired-samples T test were carried out on pre- and postoperative Lysholm scores. The significance of the difference between Lysholm Scores v.s. clinicopathological variables were tested by Chi-square, Fisher’s analysis. Correlations between potential clinicopathological factors like age, VAS, course, volume, Outerbrige scores and Lysholm scores were raised and analysed with Pearson’s coefficient(original data) or Spearman’s rank correlation coefficient(ranked data). All statistical tests were two-sided. A P-value of <0.05 was considered significant.Results: Of the 23 cases, the mean age was 34 years(fifteen to 60) with 5 males and 18 females. Pain was the most common symptom, present in 91%(n=21/23). The most common histological type were localized pigmented villonodular synovitis(LPVNS)(26% n=6/23) and ganglion cyst(GC)(22% n=5/23). The mean Lysholm scores were significantly improved from 60 pre-operatively(forty-four to76) to 96 post-operatively(ninty-one to 100). There was a linear negative correlation between the Lysholm scores and age, VAS scores, course, Outerbridge(r=-0.670, P=0.000, r=-0.651, P=0.000, r=-0.723, P=0.000, r=-0.509, P=0.007, respectively). A significant positive correlation were observed between age and VAS, course, Outerbridge(r=-0.521, P=0.005, r=0.443, P=0.017, r=0.681, P=0.000, respectively). A positive correlation was shown between the VAS scores and course(r=0.353, P=0.049).Conclusions: IFP tumours of the knee are rare and do not have specific symptoms. The symptoms correlate with the motor function. The diagnosis was established by MRI and arthroscopy and confirmed by histopathologic examination. For symptomatic solitary IFP tumour, arthroscopic resection is strongly recommended as a superior treatment choice. Increased awareness is required to diagnose this clinical condition early and to start the appropriate treatment in order to avoid morbidity. |
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