The Infrahoffatic Recess

The infrahoffatic recess is a synovium-lined cleft along the inferoposterior aspect of the infrapatellar (Hoffa) fat pad that demonstrates fluid intensity.

The main differential considerations include infrahoffatic ganglia or fluid-like tumors. The infrahoffatic recess is differentiated from these by its location within the midsagittal plane between the alar folds. It is typically between 5 mm - 15 mm. It may have a linear (most common), pipe-shaped, ovoid, or globular configuration.

Ganglions are usually lobulated and/or septated. Tumors that may mimic the infrahoffatic recess include fibroma of the patellar tendon sheath or a glomus tumor, but these are uncommon.

References

• Aydingöz U, Oguz B, Aydingöz O, Bayramoglu A, Demiryürek D, Akgün I, Uzün I. Recesses along the posterior margin of the infrapatellar (Hoffa's) fat pad: prevalence and morphology on routine MR imaging of the knee. Eur Radiol. 2005 May;15(5):988-94.
• Vahlensieck M, Linneborn G, Schild H, Schmidt HM. Hoffa's recess: incidence, morphology and differential diagnosis of the globular-shaped cleft in the infrapatellar fat pad of the knee on MRI and cadaver dissections. Eur Radiol. 2002 Jan;12(1):90-3.