PMC6166387_01
(a) Anteroposterior and (b) sagittal preoperative X-rays before the revision surgery. The iterative rupture of the extensor mechanism is explained by the fracture of the transverse patellar tunnel drilled during the initial surgery to pass the semitendinosus graft.
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The iterative rupture of the knee extensor mechanism was also an iatrogenic fracture of the transverse patellar tunnel (Figure 1).
Preoperative X-ray of the contralateral knee to measure the Caton-Deschamps index and patellar height.
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A preoperative lateral standard X-ray was taken of the contralateral knee at 30  of flexion to measure the Caton-Deschamps index and patellar height (Figure 2).
Pictures of the surgical steps. (a) With the artificial ligament in place. (b) Perioperative view with the artificial ligament and one adjustable loop. (c) With the artificial ligament and the two adjustable loops. (d) The final step when the artificial ligament and the loops are tightened. A staple is placed to secure the artificial ligament.
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The artificial ligament was then passed through the lateral retinaculum and above the patella at the junction with the quadriceps tendon in a Pulvertaft manner and through the medial retinaculum to return to its origin (Figure 3(a)). At the proximal side of the reconstruction, the two free ends of the PULLUP  BTB were inserted into each braid to close the system (Figures 3(b) and 3(c)). Then, the 2 PULLUP  BTB loops were tightened (Figure 3(d)).
(a) Anteroposterior and (b) sagittal postoperative X-rays at 3 months.
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The knee was placed in an articulated brace with compressive ice therapy for 24 hours, and a postoperative X-ray was taken (Figure 4).
(a) T2 sagittal slice and (b) T2 axial slices of the control MRI at 1-year follow-up. The axial slice corresponds to the level of the fracture of the transverse patellar tunnel. Fracture is healed and continuity of the patellar tendon is preserved.
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The MRI at 1 year showed complete healing of the patellar tendon and the bone (Figure 5).