Patellar Tendon Rupture

Patellar Tendon Rupture
Etiology

Direct Trauma

Penetrating or blunt trauma

Harvesting of middle third for ACL reconstruction
Bonamo, J.J., Krinick, JBJS-A, 1984

Post total knee replacement – acutely or chronically
Rand, J,A., Morrey, B.F, Bryan, R.S., CORR, 1989
Particularly after previous knee operations, and when partial release has been performed to achieve exposure. Most commonly an atraumatic development. One of the most dreaded complications of TKA

Indirect Trauma

Rapid loading of the tendon (eg – jumping)

Influenced by:
– systemic disease – rheumatoid arthritis, lupus, diabetes
– previous history of jumper’s knee
– local or systemic steroids
– local dysvascularity caused by surgery (especially TKA)

Clinical Considerations

Usually associated with significant pain and trauma (indirect or direct)
Tear is usually at the inferior pole of the patella, and may even avulse a piece of bone
Partial tears may be associated with full (but weak) active extension
Radiographs are helpful if patella alta exists
MRI may delineate between partial or complete tears

Biomechanics

A fulcrum directing the forces of flexion (body weight) against the force of the quads.

Amount of force transferred from the quadriceps muscle to the patellar ligament depends on the angle of knee flexion; as flexion increases the quadriceps force must increase to balance the increased body weight produced by the long arm of the femur

Joint reaction forces across the patellofemoral surface – 3 times body weight while rising from a chair and stair walking; 5 times body weight while squatting with the knee flexed to 80o.

Surgical Options

Considerations

Timing: Acute vs Delayed (2 weeks) – the results of acute repairs are generally better

Location of tear – usually inferior pole patella

Protection of Repair

Cast immobilization – can lead to significant stiffness

Defunctioning wire can support the construct – Larson and Lund, CORR 213, 1986 – superior results in group with cerclage wiring

Merseline tape has been advocated to support the construct – Lindy, Boynton, Fadale, Journal of Orthopaedic Trauma, 9-3, 1995

Avoiding patella infera

Fixing the patella with the inferior pole no more inferior than the roof of the intercondylar notch with the knee in 45o flexion.

Ensuring the knee will flex to 90o

Leaving about 1.5 cm of slack in the tendon with the knee extended

Late reconstructions

Semitendinosis augmentation (Kelikian, Surg Gynecol Obst, 1957)
Quadriceps Z-lengthening (Mandelbaum, Bartolozzi, Carney, CORR 235, 1988)
Achilles tendon allograft with calcaneal bone block (Azur, Pickering, Campbell’s, 1998)
Patellar tendon allograft (Emerson, Head, Malinin, CORR 260, 1991) – for TKA

Late reconstructions with severe contractures

Skeletal traction with semitendinosus / gracilis augmentation (Ecker, Lotke, Glazer, JBJS 61-A 1979)

Ilizarov lengthening (Isiklar, Varner, Lindsey, Bocell, CORR, 1996)

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