case_images: PMC4359866_01
case_images: Macroscopic photograph of clinical findings. A tendon defect was (1.5 cm in size) proximal to the patella that was palpable.
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case_images: fig1
case_images: At the initial examination, a tendon defect at proximal tip to the patella was palpable (Figure 1).
case_images: Lateral plain radiograph. Osteophyte formation was observed in the upper pole of the patella.
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case_images: fig2
case_images: A lateral plain radiograph image showed osteophyte formation in the upper pole of the patella (Figure 2).
case_images: MRI findings. (a) A proton density-weighted image. Continuity of the quadriceps tendon to the patella was completely disrupted. (b) A T2-weighed fat-suppressed image. There was a high-intensity area in the midsubstance of the quadriceps tendon.
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case_images: fig3
case_images: Magnetic resonance imaging (MRI) using proton density-weighted images showed interrupted continuity of the quadriceps tendon and the patella (Figure 3(a)). A fat-suppressed T2-weighted image revealed signal changes in the quadriceps tendon (Figure 3(b)).
case_images: Location of arthroscopic portals. Portal locations in the left knee. (a) Medial far proximal portal. (b) Lateral far proximal portal. (c) Medial suprapatellar portal. (d) Lateral suprapatellar portal. (e) Medial parapatellar portal. (f) Lateral parapatellar portal.
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case_images: fig4
case_images: Medial and lateral parapatellar portals, medial and lateral suprapatellar portals (patellar upper pole level), and medial and lateral far proximal portals were prepared (Figure 4).
case_images: Schema of modified Mason-Allen method.
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case_images: fig5
case_images: Smith & Nephew Inc., Andover, MA) were passed through each bone tunnel of the patella with the eyelet of the 2.4 mm drill pin; one of them was looped before passing. Subsequently, one end of the high-strength thread was passed through the quadriceps tendon using the modified Mason-Allen suture method (Figure 5), was slid over the patellar surface using suture retriever (Smith & Nephew Inc., Andover, MA), and was tied at the patellar lower pole via a small incision with the other side of the thread pulled out from the bone tunnel.
case_images: Intraoperative arthroscopic findings. (a) Arthroscopic images from the lateral suprapatellar portal. Left, patella; right, ruptured tendon. (b) Arthroscopic view from the lateral suprapatellar portal. A high-frequency radiofrequency device was inserted via the medial suprapatellar portal to debride synovia and ruptured fibers. (c) Arthroscopic view from the lateral suprapatellar portal. A suture anchor was inserted at the medial upper rim of the patella. Two bone tunnels were created at the central and lateral upper rim of the patella and two strands of #2 Ultrabraid sutures were inserted into each bone tunnel. (d) Arthroscopic view from the lateral suprapatellar portal after the repair. Continuity of the patella and the quadriceps tendon was obtained.
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case_images: fig6
case_images: The fixity was favorable and the continuity of the tendon and patella was obtained (Figures 6(a)-6(d)).
case_images: Schema for the arthroscopic suture in Case  1. (a) Two threads (a dotted line for the Mason-Allen method and a solid line for the double-loop sliding knot) were used for the central and lateral bone tunnels. (b) The thread (dotted line) in the central bone tunnel holding the tendon by the Mason-Allen method was passed through the anterior region and inside of the tunnel of the patella and was pulled out to the patellar lower rim. (c) The thread (solid line) holding the tendon over and proximal to the roof of the Mason-Allen method was next passed through the anterior region and inside of the tunnel of the patella and was pulled out to the patellar lower rim. The procedures used in (b) and (c) were also performed in the lateral bone tunnel. (d) and (e) Each thread gathered at the patellar lower rim was tied.
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case_images: fig7
case_images: The pull-out fixation schema is depicted in Figures 7(a)-7(e).
case_images: The patient could sit on his heels 2 years after surgery.
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case_images: fig8
case_images: The patient could sit on his heels 6 months after surgery (Figure 8).
case_images: Sagittal postoperative MRI proton density-weighted image. Continuity of the tendon was maintained.
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case_images: fig9
case_images: Association (JOA) scores were 100 and favorable continuity of the quadriceps tendon and patella was seen on MRI (Figure 9). Artistic activities in a deep flexed knee position (such as a Japanese tea ceremony) could be performed without problems and the patient could walk 20 km a day.
case_images: PMC4359866_02
case_images: Preoperative MRI image in Case  2. (a) A sagittal proton density-weighted image showing maintained continuity of the deep layer of the quadriceps tendon and patella, in addition to disruption and deflection of the superficial layer. (b) Short tau inversion recovery (STIR) imaging showing the same changes as in (a).
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case_images: fig10
case_images: MRI proton density-weighted images with and without fat suppression showed disruption of the superficial layer of the quadriceps tendon and maintained continuity of the deep layer (Figures 10(a) and 10(b)).
case_images: Arthroscopic view and schema from the lateral suprapatellar portal in the left knee. (a) The free space between the superior rim of the patella (left) and the torn tendon (right) was caused by the disruption of the superficial layer by the quadriceps tendon rupture. The intact deep layer is visible on the lower side. (b) The schema of (a).
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case_images: fig11
case_images: We identified the torn tendon as the superficial layer of the quadriceps tendon (Figures 11(a) and 11(b)).
case_images: Schema of the arthroscopic suture in Case  2. (a) Two threads (a dotted line for the Mason-Allen method and a solid line for the double-loop sliding knot) were used for the internal, medial, and external bone tunnels. (b) As with Case  1, after the threads were passed through both the superficial layer and the inside of the tunnel of the patella, they were then tied at the lower rim. Subsequently, only the superficial layer was repaired.
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case_images: fig12
case_images: The schema of pull-out fixation is presented in Figures 12(a) and 12(b).
case_images: Flexion was still insufficient and rehabilitation is ongoing one year after the surgery.
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case_images: fig13
case_images: One year after surgery, the Lysholm and JOA scores were 100 and 95, respectively, and mild limitation of flexion range was observed (Figure 13).
case_images: The architecture of the repaired quadriceps tendon seemed almost normal on a sagittal postoperative MRI proton density-weighted image.
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case_images: fig14
case_images: MRI showed favorable continuity of the quadriceps tendon and patella (Figure 14).