Isolated suprapatellar bursitis: Computed tomographic and arthroscopic findings

Management of an Unusual Post-arthroscopic Complication: Subquadricipital Hematoma in the Presence of Complete Suprapatellar Plica

Complete suprapatellar plica is a rare congenital anomaly that separates the suprapatellar bursa from the knee joint cavity. Although the pathological incidence of this condition is not known, it can cause patellofemoral symptoms, anterior knee pain, and rarely hemarthrosis. We report a patient with a hematoma in an unusual location just three weeks after an arthroscopic procedure, associated with a complete suprapatellar plica undetected during primary surgery. The hematoma was not in the synovial cavity, rather between the quadriceps tendon and the synovial membrane and presenting with pain and catching. This unusual location has not been reported before. Repeat arthroscopic surgery with drainage of hematoma and plica resection relieved the symptoms.

Qualitative and quantitative measures of prefemoral and quadriceps fat pads are associated with incident radiographic osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVE

To determine if qualitative and quantitative measures of prefemoral fat pad (PFP) and quadriceps fat pad (QFP) are associated with incident radiographic osteoarthritis (iROA) over 4 years in the Osteoarthritis Initiative (OAI) study.

DESIGN

Participants in this nested case-control study were selected from the OAI study with knees that had Kellgren Lawrence grades (KLG) of 0 or 1 at baseline. Case knees were defined by iROA (KLG≥ 2) over 4 years. Control knees without iROA were matched 1:1 with case knees. Magnetic resonance images (MRIs) were read at P0 (time of onset of iROA), P-1 (1 year prior to P0) and baseline, and used to assess PFP (i.e., prefemoral hyperintensity alteration, patellofemoral hyperintensity alteration, maximum axial area) and QFP (i.e., hyperintensity alteration, mass effect, maximum axial area). Conditional logistic regression analyses were performed to study the associations between PFP/QFP measures and iROA, after adjustment for covariates.

RESULTS

354 case knees with iROA were matched to 354 control knees. 66.9% of the participants were female, with an average age of 60.1 years. PFP prefemoral hyperintensity alteration measured at three time points (OR [95%CI]: 1.46 [1.18-1.82], 1.50 [1.20-1.88], 1.52 [1.22-1.89] respectively), PFP maximum axial area (OR [95%CI]: 1.07 [1.01-1.14], 1.08 [1.01-1.15], 1.08 [1.02-1.15] respectively) and QFP hyperintensity alteration (OR [95%CI]: 1.59 [1.27-2.00], 1.44 [1.13-1.82], 1.38 [1.09-1.73] respectively) were significantly associated with iROA in multivariable conditional logistic analyses. QFP mass effect measured at BL and P-1 (OR [95%CI]: 1.42 [1.11-1.82], 1.33 [1.01-1.73] respectively) were significantly associated with iROA.

CONCLUSIONS

Qualitative and quantitative measures of PFP and QFP are associated with increased iROA over 4 years.

Arthroscopic decompression of suprapatellar cyst: case report

Bursae around the knee reduce friction between moving structures. When involution of suprapatellar septum fails to occur ("complete septum"), then suprapatellar bursa may stay completely separated from the knee joint cavity to form a cystic cavity. In the case of the increased volume, suprapatellar bursitis can cause painful suprapatellar swelling. The aim is to point to the possibility of arthroscopic decompression of suprapatellar cyst. In the case presented, the indication for knee arthroscopy was based on clinical examination, ultrasonography and magnetic resonance studies. The preoperative diagnosis was verified intra-operatively, and intra-articular cyst decompression was performed by arthroscopy. At the final examination 8 months postoperatively, the patient still had no pain, swelling and had full range of motion. This minimally invasive operative procedure resulted in a satisfactory anatomic and functional outcome. In this case report, we present a patient with suprapatellar cyst submitted to arthroscopic cyst decompression.

New insights about suprapatellar cyst

Suprapatellar bursa is located between the quadriceps tendon and femur, and it develops before the birth as a separate synovial compartment proximal to the knee joint. By the fifth month of fetal life there is a suprapatellar septum between the knee joint cavity and suprapatellar bursa which later perforates and involutes in a way that a normal communication between the cavity of bursa and knee is established. A small portion of the embrionic septum can later lag as more or less expressed suprapatellar plica. In case when suprapatellar plica has a small communication with valve mechanism or in case of complete septum, bursa becomes a separate compartment and potential location for the suprapatellar cyst development. Magnetic resonance imaging is recognised as the gold standard in diagnosis of knee cysts because of its ability to show cystic nature of the lesion, its relationship with other anatomic structures, as well as to establish whether other knee pathologies are present. Considering treatment possibilities, majority of cysts around the knee resolve spontaneously and should be treated by aspiration and application of corticosteroids. Suprapatellar cyst is a very rare knee pathology and it can in some occasions be treated using open or arthroscopic surgery.