Summary

Augmentation of Medial Patellofemoral Ligament Repair with a Bio-inductive Scaffold

Abstract

Augmentation of Medial Patellofemoral Ligament Repair with a Bio-inductive Scaffold

Purpose

The purpose of this study was to evaluate the use of a biocomposite scaffold to augment a Medial Patellofemoral Ligament (MPFL) reconstruction to treat a lateral patella dislocation.
Methods?
Seven patients underwent augmentation of a Medial Patellofemoral Ligament Reconstruction with a biocomposite scaffold.There were five males (71.4%) and two females (28.6%). The patient’s ages ranged from 14 to 36 years with five patients under the age of 20 (71.4%). Five of the seven patients (71.4%) had associated osteochondral injuries of the lateral femoral condyle or patella and had surgery acutely. Two patients (28.6%) had surgery after at least one additional episode of lateral dislocation. All patient was followed for a minimum of a year.
A standard reconstruction was performed by reefing the MPFL in a pants-over-vest fashion based off the patella insertion. The reconstruction was augmented with a 5mm by 250mm implant (BioBrace®, CONMED, New Haven) shorten to 220mm. A whipstitch was placed on each end of the scaffold. The whipstitched ends were each attached to two 4.75mm anchors with eyelets, The anchor and graft were inserted into two 4.5-millimeter by 25-millimeter sockets in proximal 2/3rds of the patella. The apex/folded-over end of the scaffold was then inserted into a 7-millimeter socket in the femur and an interference screw was inserted with the knee flexed to 30 degrees and the patella centered in the trochlear groove. A hemostat was placed under the scaffold to avoid over-constraint. Preliminary biomechanical testing was done on cadaveric specimens

Results

Six patients returned to pre-injury activity levels and one patient with chronic instability achieved a higher level of activity compared to baseline due to the chronic nature of the patient's patella instability. All patients have full range of motion with good patella mobility and solid end point on lateral glide. Return to sports/work averaged 6 months (Range: 3 to 10 months). There were no wound or graft complications. One patient (14.3%) required arthroscopic lysis of adhesions and manipulation under anesthesia due to decreased flexion and achieved full range of motion afterward.
Preliminary biomechanical testing has shown that the implant has a high maximum pullout strength from the patella socket and the scaffold on implantation is as strong and stiff as the native MPFL as well as the reconstructed MPFL. The scaffold is bio-inductive, allowing for cellular migration and rapid incorporation into host tissue, and provides reinforcement for 2 years through the entire healing process. It incorporates into the bone in 12 weeks.

Conclusion

The preliminary results of this study demonstrate good functional outcomes as shown by the return to preinjury levels of activity when a biocomposite scaffold was used to augment the reconstruction of the MPFL for the treatment of lateral patella dislocation. The scaffold is easily and reproducibly inserted in the patella and femur using standard techniques. The scaffold augmentation strength is as strong and stiff as the native MPFL and acts as a matrix for tissue regeneration with incorporation into the soft tissue over 2 years and bone in 12 weeks. Further study is needed to confirm these preliminary results and compare them to other augmentation techniques.