Revision Anterior Cruciate Ligament Reconstruction with Bone–Patellar Tendon–Bone Autograft

Risk Factors

The need for ACL revision surgery can be because a patient suffers an ACL graft tear similar to the original injury at some time after returning to sports or work activities. A patient usually knows that the ACL graft has torn because the injury feels the same as what he/she experienced previously. However, when instability is observed upon evaluation early during recovery or the patient experiences a giving-way episode with even minor activities, this would indicate that the ACL graft failed to incorporate, either due to technical error or biological conditions.

Among the primary risk factors for ACL graft injury are young age and involvement in competitive sports. Several studies have shown ACL graft tear rates to be higher in younger patients. Shelbourne et al. found the ACL graft tear rate within 5 years after primary ACL reconstruction in 1415 patients was 8.7% for patients less than 18 years old, compared with 2.6% for patients 18–25 years old and 1.1% for patients greater than 25 years old. Andernord et al. studied the Swedish National Knee Ligament Register of almost 17,000 patients between 2005 and 2013 and found the risk factors for subsequent revision surgery to be the sport of soccer and adolescent age, with these two predictors having almost 3 times higher risk than other patients. Two- to 6-year follow-up from the Multicenter Orthopaedics Outcomes Network group found the rate of revision surgery was 7.7% of 980 patients, and younger age and the use of allografts were risk factors for revision ACL surgery. In a study of 402 competitive basketball or soccer athletes under age 17 at the time of ACL reconstruction, the rate of ACL graft injury was 15.7% for soccer and 8.3% for basketball.

Another risk factor for ACL graft tear is the use of allografts. Several studies have shown much higher graft tear/failure rates with allografts than with either hamstring or patellar tendon autografts. Engelman et al. found a 29% ACL revision rate using allografts, compared with 11% for autografts for young adolescents. Pallis et al. studied 120 cadets at a military academy and found the ACL revision rate to be 44% with using allografts, compared with 11% for patellar tendon autograft and 13% for hamstring autografts.

Some studies have shown higher rates of ACL revision after primary ACL surgery with the use of hamstring autografts compared with patellar tendon autografts. In a study of the Kaiser Permanente ACLR Registry for 2005–2012, the 5 year survival rate of 17,436 surgeries was 95%, and the factors associated with the risk of revision were the use of allografts, the use of hamstring autografts, male sex, younger age, lower body mass index, and Caucasian race. Similarly, a study of 12,643 patients in the Norwegian Cruciate Ligament Registry between 2004 and 2012 found the rate of revision ACL surgery was twice as high with hamstring autografts than with patellar tendon autografts.

Technical Errors

Surgical technique error is another cause of ACL graft failure. Placing the graft too far anterior may cause the graft to stretch when full flexion is obtained. However, placing the graft too far posteriorly may cause increased tension on the graft with extension. Anterior tunnel placement on the tibia can cause impingement of the graft in the intercondylar notch and decreased extension ( Fig. 89.1 ). Arthroscopic ACL reconstruction, in which the transtibial technique is used for drilling the femoral tunnel, can often result in vertical orientation of the graft ( Fig. 89.2 ). It is difficult to place the ACL graft in the correct location without knowing normal knee anatomy. The intercondylar notch in normal knees contains the ACL and posterior cruciate ligament, with little space existing between the ligaments. A properly placed graft should fit in the intercondylar notch with the knee in full hyperextension, without impingement in the notch ( Fig. 89.3 ).

Graft Choice

Graft choices for revision ACL reconstruction are the same as what is available for primary ACL reconstruction. According to a panel of 35 orthopaedic surgeons from around the world, the most common graft source used for revision ACL surgery is allograft tissue (33%), followed by either patellar tendon autograft (29%) or hamstring autograft (28%). The Multicenter ACL Revision Study found that allografts were used for revision ACL surgery 54% of the time, compared with only 27% for primary ACL reconstruction. My preference of graft choice is the patellar tendon autograft for both primary and revision ACL surgery. Given that allografts have a higher failure rate with both primary and revision surgery, I believe the best and most reliable graft source should be used with revision surgery, to be able to give the patient the best possible chance for achieving good stability and overall good outcome. A patellar tendon autograft from the contralateral knee is my first choice, but in cases where the patient has undergone ACL reconstruction with patellar tendon autografts on both knees, a reharvested patellar tendon can be successfully used. My rationale for choosing patellar tendon autograft, especially from the contralateral normal knee, is explained further in Chapter 15 of this book.