Good long-term results, but pain seen with endoscopic reconstruction for ACL ruptures

Hui C. Am J Sports Med. 2011.doi: 10.1177/0363546510379975.

A long-term follow-up of patients with ACL ruptures treated with an endoscopic reconstruction using patellar tendon autograft shows good patient-reported outcomes and range of motion. However, 70% of patients reported pain when kneeling.

Catherine Hui, MD, and colleagues studied 333 patients who underwent the procedure. The investigators excluded those without “isolated” tears, such as patients with an associated ligamentous injury, prior meniscal surgery or chondral injury, leaving 90 patients for the study.

The 15-year follow-up revealed that seven patients ruptured the graft, which was linked to having a graft inclination angle of less than 17º, according to the study abstract. The investigators found that 22 patients had a contralateral ACL rupture, which was associated with being younger than 18 years at the time of the procedure.

Lachman and instrumented tests showed that all of the patients had normal or nearly normal ligament stability. The patients had a mean IKDC score of 91 on a 100-point scale. Radiographic evaluation showed that 41% of patients had grade B osteoarthritis and 10% had grade C.

“Concern remains regarding the incidence of further anterior cruciate ligament injury and the increasing number of patients with radiographic and clinical signs of osteoarthritis, despite surgical stabilization,” the authors wrote.

The most important message with this 15-year follow-up of single-bundle patellar tendon autograft endoscopic ACL reconstruction done by one author with the same technique is the fact 51% of the patients had radiographic evidence of osteoarthritis despite overall good ligamentous stability, and this patient group was selected to be as close as possible to an “isolated ACL tear” cohort. So, the OA development could not be attributable to initial meniscal loss or initial chondral damage at the time of the ACL tear. This implicates that less than optimal postsurgical knee kinematics was achieved despite these knees still being clinically stable.

I wonder if the authors specifically correlated their reported radiographic tunnel position data on the femur and tibia in the patients who developed the OA. Perhaps less than optimal “anatomic” ACL placement could be the key promoting abnormal stresses on the tibiofemoral articular surfaces, particularly the medial compartment, which showed the most late degenerative change. I particularly wonder about the tibial placement being too much in the posterior footprint of the ACL based on the described surgical technique and their reported follow-up radiographic mean tibial tunnel position. I think the femoral tunnel likely was more anatomically positioned drilled through the anteromedial portal consistent with their reported femoral tunnel radiographic mean position.

The second important message with this study relates to their graft re-rupture rate of 8% — at first glance surprisingly high — but consistent with recent studies reporting higher re-tear rates in active patients which fit this group. However, they did correlate, based on their radiographic tunnel data, patients with a graft inclination angle <17° indicative of a vertical graft had a 10 times greater odds of an ACL graft re-tear; so less than optimal graft position may be the primary factor promoting this higher re-tear rate. So again, I wonder about overall graft position as it related to OA development in those 51% of affected patients.

– Patrick A. Smith, MD
Director of Sports Medicine, University of Missouri
Head Team Physician, University of Missouri
Arthroscopic Surgery & Sports Medicine
Columbia Orthopaedic Group
Columbia, Mo.

Disclosures: Smith is a consultant for Arthrex and receives no royalties. He is also a shareholder in Orthopedic Resources.