After 3 months of gradual improvement with physical therapy, the patient returned for a follow-up visit, concerned that her knee function was beginning to decline. Physical examination showed patella alta with a thinned and diminutive palpable tendon in the patellar tendon region. She was capable of active flexion to 90º and extension to 50º, but beyond 50º, she was unable to actively extend; she was capable of full passive extension. MRI showed a repeat full-thickness patellar tendon tear with retraction from the inferior pole of the patella; previous tears to the quadriceps tendon were healed. Because of the recurrent nature of the injury, the patient’s physical examination, MRI findings, and anticipated poor quality of remaining tendon tissue, patellar tendon reconstruction using a cadaveric Achilles tendon allograft was recommended. The patient chose surgery for potential improvement in knee range of motion, active extension, and ambulation.
The previous anterior midline incision was used and carried down through the subcutaneous tissues where a complete rupture of the patellar tendon was identified. A limited amount of good-quality tendon tissue remained at the medial aspect of the tibial tuberosity. The remaining tissue located at the patella’s inferior pole was nonviable for use in surgical repair. Retinacular contractures were released to bring the patella distally; the trochlear groove was used as the anatomic landmark for the patella resting position. During reconstruction, the knee was placed into 30° of flexion, with the patella located in the trochlear groove, and the cadaveric Achilles tendon was placed on the midline of the patella, where measurements were done to assess proper length and tension (Figure 1).
The patient’s remaining native tissue on the medial aspect of the tibial tuberosity was used to augment the Achilles tendon graft medially. The cadaveric Achilles tendon graft was primarily used to replace the central and lateral aspects of the patellar tendon. Additionally, the calcaneal bone segment at the end of the Achilles tendon graft was removed prior to use. Cadaveric and host tissues at the medial aspect of the tibial tuberosity were sutured together with a No. 1 Vicryl suture (Figure 2). The distal aspect of the cadaveric Achilles tendon was used to re-approximate the patient’s native patellar tendon insertion at the tibial tuberosity. To supplement the graft anchor, a Richards metallic ligament staple (Smith & Nephew, Memphis, Tennessee) was used to fix the distal aspect of the Achilles tendon graft into the tibial tuberosity.
Proper tensioning of the graft was performed by visualizing patella tracking during the arc-of-knee motion and properly suturing the graft to allow for functional range. The proximal aspect of the cadaveric Achilles tendon was sutured into host tissues surrounding the superior pole of the patellar and quadriceps tendon. The edges of the graft were sutured with supplemental No. 1 Vicryl sutures (Figure 3).
Before surgical closure, knee range of motion was checked and noted to be 0º to 100º. The repaired construct was stable and uncompromised throughout the entire range of motion. Patella tracking was central and significantly improved; knee stability was normal to varus and valgus stress.
The patient was placed in a knee immobilizer for 6 weeks before range of motion was allowed. Seven months postoperatively, the patient returned for a follow-up visit, ambulating with 2 forearm crutches, which was her baseline ambulatory status. Physical examination revealed passive range of motion from 0º to 130º, an extension lag of 10º, and 4/5 quadriceps strength. It was recommended the patient continue physical therapy to improve strength and range of motion.
Conclusion
This is the first report in the literature documenting a recurrent patellar tendon rupture after primary repair in a patient with a history of IM tibial nailing. It is also the first report of a cadaveric Achilles tendon allograft used as a solution to this problem. Complete reconstruction of the patellar tendon using an Achilles tendon allograft is a method commonly used for ruptures after total knee arthroplasty.4-7,23,24 This case report highlights the utility of a cadaveric Achilles tendon in the setting of a recurrent patellar tendon rupture with poor remaining tissue quality.