Anterior cruciate ligament reconstruction with hamstring tendon autograft

OVERVIEW

Chapter synopsis

This chapter details the arthroscopy-assisted technique of anterior cruciate ligament (ACL) reconstruction with a quadrupled hamstring autograft that is performed using independently drilled femoral and tibial tunnels. Specifics of graft harvesting, tunnel positioning, graft fixation, and rehabilitation are covered.

Important points

Harvest tendons carefully to maximize length.
Know how to modify the graft if overall diameter is <8 mm
Avoid graft impingement on the posterior cruciate ligament (PCL) as well as the roof of the notch with knee extension
Pre-tension graft prior to implantation
Perform secure graft fixation with the knee in extension
Use a staged rehabilitation program

Clinical/surgical pearls

Perform dissection of the semitendinosus and gracilis tendons by releasing all fascial bands; recognize that disappearance of the dimple sign indicates release of all bands from the semitendinosus.
Utilize the anteromedial portal to evaluate the pilot hole prior to femoral tunnel drilling as well as to evaluate the planned tibial tunnel to ensure the graft will not impinge on the PCL or notch.

Clinical/surgical pitfalls

Graft truncation: how to manage
Graft contamination prior to implantation
Graft fixation
Postoperative infection

Introduction

Anterior cruciate ligament (ACL) reconstruction using a quadrupled hamstring autograft has demonstrated clinical outcomes comparable to use of central third autogenous patellar tendon and quadriceps tendon. ^, The patellar tendon autograft is often the preferred graft for collegiate and professional athletes in high demand sports, such as football, basketball, and soccer, due to faster graft incorporation and faster return to sports ^, as well as lower revision rates in some studies. ^, Nonetheless, hamstring autografts have proved reliable and are especially useful in younger athletes with open physes. In addition, patients desiring improved cosmesis and those with prolonged pre-operative stiffness after initial injury or pre-existing chondromalacia patella may benefit from a hamstring graft. In our experience, once surgery is decided upon, much discussion revolves around the particular graft to be used in the reconstruction. While the surgeon’s preference and experience carry great weight, the patient may have a specific preference based on a teammate’s surgery or the recommendation of a trainer or therapist. It is for these reasons that surgeons need to be versatile in their ability to perform ACL reconstruction using a variety of grafts. Notwithstanding advances in ACL surgery, the rate of failure remains approximately 10% overall and can approach 25% for young, active athletes returning to sports. Causes of failure are myriad and are less dependent on graft choice than factors such as failure to recognize and treat associated injuries, tunnel placement and graft fixation, suboptimal rehabilitation, and reinjury. These principles apply to ACL reconstruction regardless of graft choice. When electing to use a hamstring tendon autograft, two keys to successful surgery are harvesting tendons carefully to maximize length and ensuring that the quadrupled tendon graft will have a sufficient diameter >8 mm, below which there is increased risk of failure.

Pre-operative considerations

Mechanism of injury

Most ACL injuries occur during noncontact pivoting or with knee hyperextension while landing. Females are at greater risk for ACL injury, which may be due to neuromuscular differences that include increased dynamic valgus and high abduction loads on the knee during landing as well as decreased hamstring torque and increased quadriceps activation, which increase anterior shear force on the ACL. ^,

History

Typically, patients recall that while landing or pivoting, the knee buckled with an audible pop, immediate pain, and inability to stand or continue playing. Swelling subsequently develops within a few hours, and the knee will have a painful, limited range of motion. However, such dramatic presentation will occasionally not occur, and the patient may even be able to continue playing to some degree. In chronic injury, the patient may only complain of the knee giving way with pivoting unless subsequent meniscal or chondral injury has occurred.

Physical exam

Acute setting

A comprehensive knee examination in the acute setting is not usually possible. Assess the neurovascular status of the extremity first. Second, determine the integrity of the extensor mechanism by palpation and assess any extensor lag. Note the degree of hemarthrosis, and if tense, consider aspiration to aid in the exam. Attempt to displace the patella laterally and note any tenderness over the medial patellofemoral ligament to diagnose a possible patellar dislocation, which is a key differential in acute hemarthrosis of the knee, especially in the young patient. Perform an anterior drawer test at 25 degrees flexion (Lachman’s test) by allowing the entire extremity to externally rotate to relax the hamstrings. If there is increased excursion or the endpoint is soft, an ACL tear is confirmed. Grading in the acute setting is difficult. The pivot shift is not performed acutely, as it is too painful for the patient and the knee cannot usually be fully extended as necessary for this test. Ascertain medial and lateral stability of the knee in full extension and 30 degrees flexion. Evaluate the PCL with a posterior drawer test at 90 degrees flexion. Typically, the lateral joint line will be tender to palpation due to bone contusions of the lateral femur and tibia. However, tenderness along the posterolateral joint line and over the fibular head may suggest posterolateral laxity. Be suspicious of possible associated posterolateral injury if the mechanism of injury is hyperextension or there is history of contact to the anterior aspect of the knee. Measure external tibial rotation at 30 degrees flexion and compare with the uninjured knee. Posterolateral injury is confirmed by >10 degrees increase in external tibial rotation.

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