Management of patellar tendon ruptures following total knee arthroplasty

Abstract

The extensor mechanism of the knee consists of the quadriceps muscles and tendon, the patella, patellar tendon and supporting medial and lateral retinaculum. Rupture of the patellar ligament is one of the most seriouscomplications after total knee arthroplasty. The etiology ismultifactorial. Given the complexity of these cases,which often include multiple medical problems, connectivetissue abnormalities, or multiple previous operations on thesame knee, its comorbidity. Although patellar tendon disruption during TKA is a rareoccurrence, all surgeons performing this procedure should beready to handle this potentially disastrous complication. Early accurate diagnosis is important, as the method of treatment and the outcome depend on this. However, other factors include the time since injury is very important as those treated acutely have a more favorable outcome. Rupture of the patellar tendon is most commonlycaused by a violent contraction ofthe quadriceps muscle against thefixed load of the patient’s bodyweight with the knee in a flexedposition, and occurred as aresultfrom repetitive microtrauma to thefibers of the patellar tendon. The hallmark of a patellar tendonrupture on physical examination isthe patient’s inability to activelyextend the knee against gravity.This finding, along with a painful,palpable defect in the substance ofthe tendon and demonstration ofpatella alta on a lateral radiograph,makes the diagnosis of this conditionrelatively straightforward. Complex revision total knee arthroplasty has alwaysrequired a more generous surgical exposure to prevent rupture of patellar tendon; the most common techniques for extensile exposure are quadriceps snip,tibial tubercle osteotomy, and quadriceps turndown. It is not surprising that treatment of patellar tendonrupture has not provided good results. For example, primaryrepair of the tendon alone rarely restores extensor function. Immediate surgical repair of theruptured patellar tendon is recommendedfor optimal return of function.A Bunnell-type repair withthe use of heavy nonabsorbablesutures through transosseous tunnelswith a reinforcing cerclagesuture is recommended for a securerepair. In addition, the use of a flexible cable creates a more synergistic construct with the patellar tendon. The modified technique of using semitendinosus and gracilis tendons(STG) with preserved distalinsertions in combined with tension-reducing wire, in treatment of the rupture has several advantages. First, semitendinosus and gracilis tendons are rich in tendonfibers,which are stronger than those of the fascia lata, orquadriceps-patellar retinaculum. Second, by preserving distal insertion of the tendon you provide additional stability during the early stages of tendonbone healing, and retain blood supply to promote healing of the tendon. Third, when the tendons are passed in opposite directions throughthe tunnels, force is distributed on both sides of original patellartendon. In rare instances, allograft tendons arerequired to span the defect whenlocal tissue is unavailable. It has proven to be successful in most patients. The studies emphasize the importance of tightly tensioning the allograft with the knee in full extension, Failure to provide maximaltension on the graft will result in subsequent extensor lag. Artificial ligaments can be a useful tool inligament reconstruction, avoiding the necessity of tendonharvesting procedures and the possibility of donor sitemorbidity.The use of the LARS ligament is well established incases of cruciate and collateral knee ligament reconstruction and can also be used for thereconstruction of a neglected patella tendonin an elderly, and low demand patients.