Infrapatellar Pain in a Young Woman
Published on Cancer Network (http://www.cancernetwork.com)
Infrapatellar Pain in a Young Woman
Photoclinic [1] | June 04, 2011
By RheumatologyNetwork Staff [2]
A 23-year-old woman who reported experiencing direct trauma to her right knee on a hard surface 3
months earlier was admitted to the arthroscopy unit with complaints of decreased range of motion
(flexion, 90°; extension, 75°) and intractable pain.
A 23-year-old woman who reported experiencing direct trauma to her right knee on a
hard surface 3 months earlier was admitted to the arthroscopy unit with complaints of decreased
range of motion (flexion, 90°; extension, 75°) and intractable pain. She also had swelling in the knee.
Physical examination revealed the “bulge sign,” a synovial fluid wave with squeezing of the knee at
the medial aspect characteristic of small effusions. The patellar tendon and femoral condyles were
tender to palpation with the knee extended.
Ultrasonography showed mild effusion that was remarkable on quadriceps contraction.
The sulcus angle and trochlear depth were normal.
The patient underwent arthroscopy with resection of hypertrophic fat pad tissue in the infrapatellar
area (photographs). A diagnosis was made with the arthroscopy. What does it show?
What is your diagnosis?
Find the answer on the next page.
The patient had a hypertrophic infrapatellar fat pad (Hoffa disease) and small medial plica; both
were resected under arthroscopic control. Hoffa disease is an obscure but consistent cause of
anterior knee pain that often is perceived as a rare condition. The diagnosis usually is made by
exclusion.1
Hoffa disease was described in 1904 by Albert Hoffa, a German surgeon. The condition is
characterized by pain in the infrapatellar and retropatellar areas that often is exacerbated by knee
movement; it results from femorotibial impingement with an enlarged infrapatellar fat pad. The
impingement mechanism eventually leads to cartilage damage (top and middle photographs, below).
In addition, the infrapatellar fat pad is considered the source of several proinflammatory molecules
in knee osteoarthritis.2
The prevalence of Hoffa disease is unknown. In a study by Kumar and associates,1 the condition was
present as an isolated lesion in 1.3% of patients who underwent arthroscopy. They found an overall
incidence of 6.8%.
Arthroscopy is an accurate tool for the diagnosis and definitive management of a hypertrophic fat
pad. Direct observation of inflammation, fibrosis, and impingement is helpful in planning the amount
of tissue to resect.
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Infrapatellar Pain in a Young Woman
Published on Cancer Network (http://www.cancernetwork.com)
In a case series of 62 patients, von Engelhardt and colleagues3 concluded that
MRI should be considered for the diagnosis of infrapatellar fat pad impingement. Edema of the Hoffa
fat pad was the most important MRI criterion for identifying the impingement in this series.
Use of musculoskeletal ultrasonography is increasing in office practice. This imaging modality may
be useful in the diagnosis of patellar tendinitis, infrapatellar bursitis, and jumper’s knee, all causes of
infrapatellar pain that may mimic a hypertrophic fat pad. Patients with abnormal flattening of the
trochlear groove have episodes of patellar dislocation and anterior knee pain. A normal trochlear
depth and sulcus angle measured by ultrasonography ruled out patellar instability in this patient.
A hypertrophic mediopatellar plica may mimic or even be associated with Hoffa disease, as was the
case in this patient. In my opinion, the relationship between Hoffa disease and the mediopatellar
plica has physiopathological importance in 2 ways. One, the inflammation and fibrosis of the
mediopatellar plica resulting from femoral condyle impingement may involve the infrapatellar fat
pad. Although the infrapatellar fat pad is located centrally beneath the patellar tendon, it can appear
to be joined medially as a continuous structure in the presence of the medial plica. Two, the
presence of a hypertrophic medial plica may decrease the motion of the fat pad medially with an
impingement mechanism. I agree with Saddik and coworkers4 that the precise relationship with
Hoffa impingement is unclear.
Excluding a 2009 study by Brooker and colleagues,5 most publications about a hypertrophic
infrapatellar fat pad have been case reports; therefore, a conservative treatment has not been
standardized. Because pain and swelling are common clinical manifestations, analgesics, NSAIDs,
and intra-articular corticosteroid injections are used frequently before arthroscopy is considered.
Most patients improve symptomatically after arthroscopic resection of a hypertrophic fat pad, which
usually is indicated if conservative therapeutic options, including physical therapy, are not
successful.
The surgical technique performed in this case was similar to that described by Kumar and
colleagues.1 I usually use high-portal arthroscopic resection, which allows for excellent triangulation
with the surgical instruments and provides a panoramic view of the infrapatellar recess (bottom
photograph, above). During the procedure, extension of the knee or pressure applied on the patellar
tendon by an assistant often facilitates grasping of the fat pad tongue. This maneuver also provides
a better idea about the size of the fat pad and avoids violation of the anterior capsule and injury of
the patellar tendon.
A motorized shaver can be used to remove the hypertrophic fat pad. However, I prefer using a
basket forceps placed through the anterolateral portal. After a complete release of the fat pad, the
grasping forceps placed in the superomedial portal is pulled out with a gentle screw-like movement.
Because fat is friable tissue that can be entrapped in the superomedial portal,6 I recommend
reviewing it before finalizing the procedure.
Quadriceps strength and range of motion exercises made up the main physiotherapy program for
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Infrapatellar Pain in a Young Woman
Published on Cancer Network (http://www.cancernetwork.com)
this patient. One month after the surgical intervention, she was asymptomatic with complete
recovery of range of motion.
References:
1. Kumar D, Alvand A, Beacon JP. Impingement of infrapatellar fat pad (Hoffa’s disease): results of
high-portal arthroscopic resection. Arthroscopy. 2007;23:1180-1186.e1.
2. Distel E, Cadoudal T, Durant S, et al. The infrapatellar fat pad in knee osteoarthritis: an important
source of interleukin-6 and its soluble receptor. Arthritis Rheum. 2009;60:3374-3377.
3. von Engelhardt LV, Tokmakidis E, Lahner M, et al. Hoffa’s fat pad impingement treated
arthroscopically: related findings on preoperative MRI in a case series of 62 patients. Arch Orthop
Trauma Surg. 2010;130:1041-1051.
4. Saddik D, McNally EG, Richardson M. MRI of Hoffa’s fat pad. Skeletal Radiol. 2004;33:433-444.
5. Brooker B, Morris H, Brukner P, et al. The macroscopic arthroscopic anatomy of the infrapatellar
fat pad. Arthroscopy. 2009;25:839-845.
6. González AC. Fat pad entrapment in suprapatellar pouch following previous arthroscopic resection
of infrapatellar fat pad and medial plica: a rare complication. J Musculoskel Pain. 2001;9:95-98.
Source URL: http://www.cancernetwork.com/photoclinic/infrapatellar-pain-young-woman
Links:
[1] http://www.cancernetwork.com/photoclinic
[2] http://www.cancernetwork.com/authors/rheumatologynetwork-staff
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