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Patella dislocation with vertical axis rotation: the "dorsal fin" patella.

Gamble D, Otto Q, Carrothers AD, Khanduja V - Case Rep Orthop (2015)

Bottom Line: Closed reduction in the emergency room was unsuccessful but was achieved in theatre under general anaesthetic with muscle relaxation.Attempts to reduce vertical patella dislocations under sedation with excessive force or repeatedly without success should be avoided to prevent unnecessary damage to the patellofemoral joint.In this clinical situation we recommend closed reduction under general anaesthetic followed by immediate knee arthroscopy under the same anaesthetic to ensure that there is no chondral damage to the patella or femoral trochlea and to rule out an osteochondral fracture.

View Article: PubMed Central - PubMed

Affiliation: Trauma and Orthopaedic Department, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hill Road, Cambridge CB2 0QQ, UK.

ABSTRACT
A 44-year-old woman presented following minor trauma to her right knee. While dancing she externally rotated around a planted foot and felt sudden pain in her right knee. She presented with her knee locked in extension with a "dorsal fin" appearance of the soft tissues tented over the patella. This was diagnosed as a rare case of an intraarticular patella dislocation, which was rotated 90 degrees about the vertical axis. Closed reduction in the emergency room was unsuccessful but was achieved in theatre under general anaesthetic with muscle relaxation. Postreduction arthroscopy demonstrated that no osteochondral or soft tissue damage to the knee had been sustained. In patients presenting with a knee locked in extension with tenting of skin over the patella (the "dorsal fin" appearance), intra-articular patella dislocation should be suspected. Attempts to reduce vertical patella dislocations under sedation with excessive force or repeatedly without success should be avoided to prevent unnecessary damage to the patellofemoral joint. In this clinical situation we recommend closed reduction under general anaesthetic followed by immediate knee arthroscopy under the same anaesthetic to ensure that there is no chondral damage to the patella or femoral trochlea and to rule out an osteochondral fracture.

No MeSH data available.


Related in: MedlinePlus

Anterior-posterior view of the patients' knee with the characteristic “dorsal fin” appearance of tenting of the skin over the laterally displaced patella.
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fig1: Anterior-posterior view of the patients' knee with the characteristic “dorsal fin” appearance of tenting of the skin over the laterally displaced patella.

Mentions: A 44-year-old woman presented to the accident and emergency department with acute right knee pain. While dancing the quick-step (an energetic and form-intensive style) she externally rotated about a planted right foot and felt an acute pain in her right knee with her patella shifting laterally. On arrival at hospital her right leg was locked in full extension and she was in severe pain. The patient had no history of previous knee trauma, prior dislocations, or joint hypermobility. She has no other past medical history to suggest any cause for dislocation of the patella. In particular she had no history of paediatric lower limb alignment problems that would predispose her to a dislocated patella. On inspection of the limb there was a deformity of her right patella indicative of a rare patellar dislocation (Figures 1 and 2). The patella appeared rotated on its vertical axis and the skin over the knee joint was tented. It was fixed in position. There was a mild joint effusion and no joint line tenderness. Her range of motion at the right knee was significantly reduced with any flexion from full extension causing the patient significant pain. She was able to straight leg raise on examination indicating that her extensor mechanism was intact. The limb was otherwise neurovascularly intact. The examination of the contralateral limb was entirely normal.


Patella dislocation with vertical axis rotation: the "dorsal fin" patella.

Gamble D, Otto Q, Carrothers AD, Khanduja V - Case Rep Orthop (2015)

Anterior-posterior view of the patients' knee with the characteristic “dorsal fin” appearance of tenting of the skin over the laterally displaced patella.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4390077&req=5

fig1: Anterior-posterior view of the patients' knee with the characteristic “dorsal fin” appearance of tenting of the skin over the laterally displaced patella.
Mentions: A 44-year-old woman presented to the accident and emergency department with acute right knee pain. While dancing the quick-step (an energetic and form-intensive style) she externally rotated about a planted right foot and felt an acute pain in her right knee with her patella shifting laterally. On arrival at hospital her right leg was locked in full extension and she was in severe pain. The patient had no history of previous knee trauma, prior dislocations, or joint hypermobility. She has no other past medical history to suggest any cause for dislocation of the patella. In particular she had no history of paediatric lower limb alignment problems that would predispose her to a dislocated patella. On inspection of the limb there was a deformity of her right patella indicative of a rare patellar dislocation (Figures 1 and 2). The patella appeared rotated on its vertical axis and the skin over the knee joint was tented. It was fixed in position. There was a mild joint effusion and no joint line tenderness. Her range of motion at the right knee was significantly reduced with any flexion from full extension causing the patient significant pain. She was able to straight leg raise on examination indicating that her extensor mechanism was intact. The limb was otherwise neurovascularly intact. The examination of the contralateral limb was entirely normal.

Bottom Line: Closed reduction in the emergency room was unsuccessful but was achieved in theatre under general anaesthetic with muscle relaxation.Attempts to reduce vertical patella dislocations under sedation with excessive force or repeatedly without success should be avoided to prevent unnecessary damage to the patellofemoral joint.In this clinical situation we recommend closed reduction under general anaesthetic followed by immediate knee arthroscopy under the same anaesthetic to ensure that there is no chondral damage to the patella or femoral trochlea and to rule out an osteochondral fracture.

View Article: PubMed Central - PubMed

Affiliation: Trauma and Orthopaedic Department, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hill Road, Cambridge CB2 0QQ, UK.

ABSTRACT
A 44-year-old woman presented following minor trauma to her right knee. While dancing she externally rotated around a planted foot and felt sudden pain in her right knee. She presented with her knee locked in extension with a "dorsal fin" appearance of the soft tissues tented over the patella. This was diagnosed as a rare case of an intraarticular patella dislocation, which was rotated 90 degrees about the vertical axis. Closed reduction in the emergency room was unsuccessful but was achieved in theatre under general anaesthetic with muscle relaxation. Postreduction arthroscopy demonstrated that no osteochondral or soft tissue damage to the knee had been sustained. In patients presenting with a knee locked in extension with tenting of skin over the patella (the "dorsal fin" appearance), intra-articular patella dislocation should be suspected. Attempts to reduce vertical patella dislocations under sedation with excessive force or repeatedly without success should be avoided to prevent unnecessary damage to the patellofemoral joint. In this clinical situation we recommend closed reduction under general anaesthetic followed by immediate knee arthroscopy under the same anaesthetic to ensure that there is no chondral damage to the patella or femoral trochlea and to rule out an osteochondral fracture.

No MeSH data available.


Related in: MedlinePlus