Anterior cruciate ligament reconstruction : patellar tendon, Gore-Tex, Kennedy LAD and tibia tunnel ingrowth

Abstract

Anterior cruciate ligament injury can induce permanent functional impairment in the physically active individual. Different methods to repair or replace the tom ligament have been tried and investigated. This thesis investigates three principally different grafts used in ACL reconstruction; autogenous tendon, stent/augmentation and prosthetic. Special emphasis has been put on stability examined with KT-1 000, Lachman and pivot shift tests, functional outcome measured with Lysholm, Tegner and IKDC scores and finally radiological evaluation of the tibia-tunnel.

In two studies, one on chronic (>6 months) ACL injuries and one on acute (<3 weeks) with 40 patients in each, we investigated short- and midterm results. The patients were randomised between ACL reconstruction performed with the use of autogenous patellar-tendon graft or a weaker autogenous graft that was augmented with a polypropylene braid. At follow-up after 4 and 7 years, respectively, we found no statistical difference in stability tests, functional or activity scores. Both groups showed stable improvement concerning scores and arthrometry compared to preop. No advantage was found with the addition of the LAD.

In a prospective study on ten patients with a bone-patellar tendon-bone reconstruction, tibia condyle bone mineral density (BMD), bone ingrowth and changes in diameter in the tibia bone tunnel was studied by quantified computed tomography postoperatively and after 1, 3, 6 and 12 months.

There was no sign of bone ingrowth in the bone tunnels. The tunnel diameter initially increased. After 1 year 5 patients had a smaller, 2 patients had the same and 2 patients had a bigger diameter compared to postoperative examination. There was a decrease in tibia condyle BMD at 3 months, after 12 months BMD had increased but was not restored completely. We concluded that: Autogenous bone-tendon-bone grafts is not, after one year, incorporated into the tibia-tunnel by bone ingrowth into the central tendon part of the graft. Although the patients were rehabilitated according to an accelerated protocol they showed the same amount of bone mineral loss as reported in patients with inactivity/post-traumatic induced osteopenia.

Seventeen out of 22 patients reconstructed with the Gore-Tex prosthetic ligament were evaluated after 14 years. They were evaluated with the KT-1 000 arthrometer, CT scans of the tibia-tunnel, IKDC, Lysholm and Tegner scores, pivot shift, Lachman test and visual analogue scale (VAS) score for pain. We found osteolytic enlargement in the tibia-tunnel in 14 of the examined 17 patients. Our study showed that all osteolysis are not symptomatic and can not be detected with evaluation scores, clinical or arthrometric exams.

The 80 acute and chronic patients in the 2 first studies were evaluated 14 years after reconstruction. Follow-up protocol was the same with the addition of IKDC score, radiological examination with weight bearing anteroposterior and lateral projections of the knee and quantified computed tomography (QCT) of the tibiatunnel.

In this long-term follow-up we found no adverse reactions to augmentation and it is equal to the patellar tendon technique in maintaining achieved stability over time, therefore it seems to be a safe complement if a graft of inadequate strength has to be used. LAD and chronic injuries was associated with more tibia- tunnel expansions compared to PT and acute injuries. PT reconstructions had a tendency towards more patella-/femoral joint degeneration. Chronic injuries had significantly more arthrotic changes and lower Lysholm score.