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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

Image from arthroscopy showing fibrillation of the lateral trochlear cartilage.
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fig6: Image from arthroscopy showing fibrillation of the lateral trochlear cartilage.

Mentions: Immediate postreduction arthroscopy was conducted to assess the degree of underlying damage, guide postoperative recovery, repair any potential damage, and define the long-term prognosis of the knee joint. We demonstrated no significant damage to underlying structures, particularly no osteochondral defects, medial patellofemoral ligament rupture, or damage to the retinaculum (Figures 5 and 6). There are reports of significant soft tissue and osteochondral damage of the knee following this type of injury [12, 17, 18]. This is the first case in the literature to provide postreduction arthroscopic imaging showing that successful reduction can be achieved without damage to the joint. In our case this would be consistent with the relatively trivial mechanism of injury and limited manipulations with inadequate sedation and muscle relaxant. Although of note most cases of reduced patella dislocation are associated with osteochondritis.


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

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

Image from arthroscopy showing fibrillation of the lateral trochlear cartilage.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig6: Image from arthroscopy showing fibrillation of the lateral trochlear cartilage.
Mentions: Immediate postreduction arthroscopy was conducted to assess the degree of underlying damage, guide postoperative recovery, repair any potential damage, and define the long-term prognosis of the knee joint. We demonstrated no significant damage to underlying structures, particularly no osteochondral defects, medial patellofemoral ligament rupture, or damage to the retinaculum (Figures 5 and 6). There are reports of significant soft tissue and osteochondral damage of the knee following this type of injury [12, 17, 18]. This is the first case in the literature to provide postreduction arthroscopic imaging showing that successful reduction can be achieved without damage to the joint. In our case this would be consistent with the relatively trivial mechanism of injury and limited manipulations with inadequate sedation and muscle relaxant. Although of note most cases of reduced patella dislocation are associated with osteochondritis.

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