1. The Clamshell Fracture and Adjunctive Acetabuloplasty in the Arthroscopic Osteosynthesis of Femoral Head Fractures With Femoroacetabular Impingement 
Dean K. Matsuda, M.D. 
Arthroscopy Techniques 
Volume 1, Issue 1, Pages e5-e10 (September 2012)
DOI: /j.eats
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2. Figure 1
Detail of preoperative anteroposterior pelvis radiograph showing right femoral head fracture with double-density shadow (arrows) and concentric reduction after closed reduction.
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3. Figure 2
Same preoperative anteroposterior radiograph of right hip shown in Fig 1 emphasizing acetabular crossover sign at intersection of anterior rim (red line) and posterior rim (blue line) and ischial spine sign, both radiographic indicators of focal pincer FAI from a retroverted acetabulum. A pistol-grip deformity (arrow) confirms cam-type FAI morphology.
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4. Figure 3
Supine arthroscopic view with 70° arthroscope in anterolateral portal of right hip showing 1 large chondral surface (a) of clamshell fracture. (FH, femoral head fracture defect; L, labrum; ORIF, open reduction–internal fixation.)
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5. Figure 4
Supine arthroscopic view of right hip from anterolateral portal showing clamshell fracture floating above fracture donor site. One should note the articular cartilage on the superior (a) and inferior (b) aspects of the osteochondral fracture. (Ac, acetabulum; FH, femoral head.)
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6. Figure 5
Supine arthroscopic view of right hip from anterolateral portal of clamshell fracture being pried open with 45° microfracture awl. (a, superior fragment; b, inferior fragment; L, labrum.)
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7. Figure 6
Virtual path (red line) in setting of acetabular overcoverage from pincer FAI. One should note the relative shallow angle of attack for screw fixation.
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8. Figure 7
Improved steeper path (red line) for screw fixation after arthroscopic acetabular rim reduction.
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9. Figure 8
Supine arthroscopic image of right hip showing proximal headless cannulated compression screw being inserted between trimmed acetabular rim (AR) and surgically detached labrum (L) improving path of internal fixation of osteochondral fracture fragment (a).
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10. Figure 9
Supine arthroscopic view from anterolateral portal of right femoral head fracture construct after arthroscopic osteosynthesis with 2 headless compression screws. One should note the screw heads buried below the level of articular cartilage and engaging the femoral head subchondral bone (arrows). (ORIF, open reduction–internal fixation.)
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11. Figure 10
Supine arthroscopic image from anterolateral portal after arthroscopic osteosynthesis of right femoral head osteochondral fracture (a), acetabular rim trimming, labral refixation, and femoral osteoplasty (not shown) before release of hip distraction. (ORIF, open reduction–internal fixation.)
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12. Figure 11
Detail of right hip from anteroposterior pelvis radiograph 24 months postoperatively. There is evidence of osseous union without joint encroachment by intact screws. There is no radiographic evidence of osteoarthrosis or osteonecrosis. The arrow shows the proximal extent of rim reduction below which the previous crossover sign is no longer present.
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