Comprehensive Functional Capacity Evaluation for the Determination of Safe Return to Play Following ACL Reconstruction Research

Accounting for up to 64% of knee ligament injuries incurred in cutting and pivoting sports, anterior cruciate ligament (ACL) tears are one of the most common knee ligament injuries in athletes1. Patients lacking an intact ACL have a significant risk of functional instability, damage to the menisci and articular cartilage, and osteoarthritis; therefore, reconstruction of the torn ACL is often performed with the goal of restoring stability to the knee and decreasing risk of subsequent injury2,3. Advances in ACL reconstruction (ACLR) and rehabilitation have led to improved outcomes and expedited return to play (RTP), however there is a tremendous amount of variability in the criteria used by physicians to give clearance for RTP following ACLR4.

The FCE consists of three separate components: subjective, clinical, and functional. The subjective component is comprised of questionnaires to track self-reported outcomes (IKDC, KOS-ADL, and KOS-sport)7,8,9. The clinical component includes assessment for effusion, active ROM, passive ROM, and strength of the muscles surrounding the knee. The functional component consists of a landing form assessment (Figure 1),
hop testing, and three task specific qualitative assessments: hop testing, shuttle run, and vertical jump. All components are administered sequentially once the patient’s physician has determined that the patient might be ready to RTP.

The FCE demonstrated a significant ability to determine whether a patient was ready for safe RTP based on ipsilateral reinjury rates (2.6% vs. 15.4%, p = 0.008). Two injuries to the contralateral ACL were seen in patients who passed the FCE, however this may be a consequence of those individuals being susceptible to ACL injury. Patients who passed the FCE reported significantly higher subjective scores and demonstrated greater quadriceps strength than those who failed. In fact, the greatest improvement seen in patients who passed the FCE on a second attempt was in quadriceps strength (QI). FCE can be utilized to standardize the process of advising patients wishing to RTP following ACLR.

ACL Fixation Study

The anterior cruciate ligament (ACL) in the knee is frequently torn in athletes (Fig. 1), affecting up to 400,000 people every year (1). The success of ACL reparation surgery is related to sound initial biomechanical strength of fixation. There are many different fixation methods for soft tissue grafts. These include interference fixation, sutures over a post, and femoral cross-pin fixation. With current procedures, the tibial side interference screw has been shown to slip with the cross-pin fixation (2). The purpose of this study was to test two different hypotheses. First, we hypothesize that a tibial cross-pin performs as well as the clinically proven femoral cross-pin. Secondly, we hypothesize the interference screw will perform better on a femur than on a tibia. We designed a new surgical procedure to see whether it will exhibit superior strength and efficiency in comparison to the traditional, accepted practice that utilizes the femoral cross-pin fixation.

Changing the cross-pin to the tibia and interference screw to the femur can be considered advantageous according to our results. When considering yield load, the tibial cross-pin is better than the femoral cross-pin, the femoral interference screw is better than the tibial interference screw, the tibial cross-pin is better than the tibial interference screw, and there is no significant difference between the femoral cross-pin and the femoral interference screw. The yield load was also significantly higher with the combination of tibial cross-pin and femoral interference screw than with the traditional femoral cross-pin and tibial interference screw (Fig. 9). Regarding cyclic displacement and ultimate load, the femur is better than the tibia with both fixations, and the cross-pin is better than the interference screw (Fig. 5 and Fig. 8). The femur has better bone quality compared to the tibia, especially in regards to the interference screw. The cross-pin proves to be stronger because the graft’s looped end wraps around it while the cross-pin is embedded in bone. Due to the graft having both a looped and free end, both a cross-pin and an interference screw are necessary. Therefore, we recommend to have the interference screw in the femur and the cross-pin in the tibia based on biomechanical properties.

In addition to the biomechanical advantages, there are also clinical advantages to a tibial cross-pin and femoral interference screw. Placing the cross-pin in the tibia is less invasive because it is relatively subcutaneous. This decreases the risk for painful prominent hardware on the tibia, and decreases the risk for deep infection of hardware and the graft at the tibial wound. Tibial cross-pin fixation also allows the surgeon additional benefits of all-epiphyseal fixation on the tibia in skeletally immature cases and increased ease in graft tensioning during final graft fixation because no additional hand is needed to manually reduce the tibia.
Using a tibial cross-pin and femoral interference screw is preferred to a femoral cross-pin and tibial interference screw for anterior cruciate ligament repair surgery.

Research: Soft Tissue ACL Graft Study: A Comparison Study of Femoral Cross Pin Fixation with Tibial Interference Screws vs. Tibial Cross-Pin Fixation with Femoral Interference Screw

The anterior cruciate ligament (ACL) in the knee is frequently torn in athletes, affecting up to 400,000 people every year (1). The success of ACL reparation surgery is related to sound initial biomechanical strength of fixation. There are many different fixation methods for soft tissue grafts. These include interference fixation, sutures over a post, and femoral cross-pin fixation. With current procedures, the tibial side interference screw has been shown to slip with the cross-pin fixation (2). The purpose of this study was to test two different hypotheses. First, we hypothesize that a tibial cross-pin performs as well as the clinically proven femoral cross-pin. Secondly, we hypothesize the interference screw will perform better on a femur than on a tibia. We designed a new surgical procedure to see whether it will exhibit superior strength and efficiency in comparison to the traditional, accepted practice that utilizes the femoral cross-pin fixation.

Changing the cross-pin to the tibia and interference screw to the femur can be considered advantageous according to our results. When considering yield load, the tibial cross-pin is better than the femoral cross-pin, the femoral interference screw is better than the tibial interference screw, the tibial cross-pin is better than the tibial interference screw, and there is no significant difference between the femoral cross-pin and the femoral interference screw. The yield load was also significantly higher with the combination of tibial cross-pin and femoral interference screw than with the traditional way of femoral cross-pin and tibial interference screw (Fig. 9). Regarding cyclic displacement and ultimate load, the femur is better than the tibia with both fixations, and the cross-pin is better than the interference screw. The femur has better bone quality compared to the tibia, especially in regards to the interference screw. The cross-pin proves to be stronger because the graft’s looped end wraps around it while the cross-pin is embedded in bone. Due to the graft having both a looped and free end, both a cross-pin and an interference screw are necessary.

Therefore, we recommend to have the interference screw in the femur and the cross-pin in the tibia based on biomechanical properties (Fig. 5 and Fig. 8).
In addition to the biomechanical advantages, there are also clinical advantages to a tibial cross-pin and femoral interference screw. Placing the cross-pin in the tibia is less invasive because it is relatively subcutaneous. This decreases the risk for painful prominent hardware on the tibia, and decreases the risk for deep infection of hardware and the graft at the tibial wound. Tibial cross-pin fixation also allows the surgeon additional benefits of all-epiphyseal fixation on the tibia in skeletally immature cases and increased ease in graft tensioning during final graft fixation because no additional hand is needed to manually reduce the tibia.

Using a tibial cross-pin and femoral interference screw is preferred to a femoral cross-pin and tibial interference screw for anterior cruciate ligament repair surgery.

Anterior Cruciate Ligament Reconstructive Surgery

Anterior Cruciate Ligament (ACL) anatomic reconstructive surgery is typically performed after the injured knee regains full range of motion and proper muscle control, generally three to four weeks following the injury. During ACL surgery, the torn ligament is replaced (reconstructed) with a graft because the ligament is so damaged that a simple repair is usually not possible. Common grafts used to replace the torn ligament include the hamstring tendons, bone-patellar tendon-bone, quadriceps tendon or allografts from cadavers. The goals of the surgery are to reconstruct the torn ligament, repair any other damaged structures (including meniscus, other ligaments, or cartilage) and restore function and stability to the knee.

Dr. Chudik performs ACL surgery with the assistance of an arthroscope, a camera that inserts into small incisions and allows him to view the inside of the knee joint. The surgery is usually performed as an outpatient procedure (go home the same day) with general anesthesia and an adductor or femoral nerve block. The nerve block involves injecting numbing medicine around the nerves of the leg by the anesthesiologist just prior to the surgery. The torn ACL is replaced by a graft. Each graft type has its own risks and benefits. Prior to surgery, Dr. Chudik will discuss the type of graft that is best for you. During the surgery, the other ligaments, meniscus and cartilage of the knee are evaluated and treated appropriately. Arthroscopically, the torn remnants of the ACL are maintained, the bone prepared, and the graft is placed anatomically where the injured ACL used to be. The graft is held in position with special fixation devices that usually do not need to be removed.