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

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Trauma Surgery

Background:

• Intra-articular patella dislocation is a rare knee injury.
• A characteristic "dorsal fin" appearance of the knee can indicate this condition.
• Early diagnosis and appropriate management are crucial to prevent further joint damage.

Purpose of the Study:

• To report a rare case of intra-articular patella dislocation.
• To highlight the clinical presentation and diagnostic challenges.
• To recommend optimal management strategies for this injury.

Main Methods:

• Case report of a 44-year-old female patient with knee trauma.
• Initial closed reduction attempt in the emergency room.
• Successful closed reduction under general anesthesia with muscle relaxation in the operating theater.
• Post-reduction knee arthroscopy to evaluate for intra-articular damage.

Main Results:

• The patient sustained a 90-degree vertical intra-articular patella dislocation.
• Closed reduction was unsuccessful under sedation but achieved under general anesthesia.
• Post-reduction arthroscopy revealed no osteochondral or soft tissue damage to the knee.
• The "dorsal fin" sign was a key indicator of the dislocation.

Conclusions:

• Intra-articular patella dislocation should be suspected in patients with a locked knee and "dorsal fin" sign.
• Avoid forceful or repeated reduction attempts under sedation due to risk of iatrogenic damage.
• Recommend closed reduction under general anesthesia followed by immediate arthroscopy to assess and manage chondral and osteochondral integrity.