The use of bioabsorbable cross-pin transcondylar fixation has remained a viable option for femoral fixation in anterior cruciate ligament reconstruction. Although numerous biomechanical studies have demonstrated high fixation strength and minimal slippage with use of this method of fixation, there have been increasing reports of a variety of clinical complications associated with these implants. We reviewed the literature for all complications associated with the Bio-TransFix implant and present a case report of a patient status after ACL reconstruction using Bio-TransFix cross-pin femoral fixation with iliotibial band friction syndrome from a broken cross-pin four month post-operatively.
Anterior cruciate ligament injuries are a significant cause of disability in active individuals with an estimated incidence of 80,000–200,000 ACL injuries occurring in the United States each year [
A 29-year-old female presented to our orthopaedic service following a twisting injury during martial arts, where she heard her right knee pop and experienced immediate pain and swelling in her knee. Physical examination demonstrated +2 Lachman and +1 pivot in her right knee. MRI confirmed full thickness ACL tear, as well as medial and lateral meniscal pathology with a lateral meniscal tear. Arthroscopic ACL reconstruction of the patient’s right knee was performed using allograft and the Bio-TransFix system (Arthrex; Naples, FL). Following drilling of the tibial tunnel and guide placements, the Bio-TransFix guide and pin were inserted and secured in the graft. An 8–10 mm IntraFix screw and sleeve construct were then inserted at this time. The graft was noted to be taut, and full extension showed no impingement both on the PCL and on the notch. There were no intraoperative complications. At six weeks after the ACL reconstruction procedure, clinical examination revealed some mild wound breakdown at the tibia and a prominence over the lateral incision, through which the cross-pin was inserted. The patient’s range of motion was from 0 to 90 at this time. Lachman test was negative. The patient had no symptoms of instability. At four months after ACL reconstruction, the patient was doing well, but was still having pain over the lateral incision. An MRI of the right knee demonstrated a broken, displaced cross-pin. The proximal portion of the pin was displaced into the adjacent soft tissues and surrounded by extensive edema and a thickened iliotibial band (Figures
Axial PD fat suppressed T2-weighted images of a right knee in a patient with prior anterior cruciate reconstruction demonstrate a fractured Bio-TransFix cross pin (red arrows).
Coronal fat suppressed T2-weighted images demonstrate that the proximal portion of the pin has backed out of the distal femur and is found within the adjacent soft tissues where it is surrounded by edema (blue arrows) and a thickened iliotibial band (green arrows). The distal portion of the pin (red arrows) and ACL graft are intact.
The patient continued to have pain and elected to undergo surgery. Under general anesthesia, an incision over the previous one was performed. The IT band was split and the underlying soft tissue palpated. The Bio-TransFix pin was found to be broken and was then removed with a clamp (Figure
Broken tip of Bio-TransFix implant.
Mechanical fixation can be categorized as direct or indirect. Direct fixation, as seen with interference screws, staples and spiked washers, refers to compression of the soft tissue to allow direct contact healing between the graft and the bone surface without the development of a fibrous interzone normally seen in nonanatomic fixation methods. [
Metal cross-pin femoral fixation was first described by Clark et al. [
The Bio-TransFix femoral fixation device places a bioabsorbable pin across the femur traversing the femoral tunnel for secure femoral fixation of the graft construct acting as transverse suspension bar perpendicular to pullout forces. As demonstrated by Ahmad et al. in a biomechanical study using 33 porcine femora to evaluate femoral soft tissue fixation, the Bio-TransFix cross-pin fixation provided high fixation strength and sufficient resistance against slippage in comparison to the conventional interference screw fixation and other similar devices [
While biomechanical studies appear to support the use of the Bio-TransFix and TransFix femoral fixation devices, there is a paucity of clinical studies with long-term followup. One controlled prospective randomized study with 2-year followup demonstrated no statistically or clinically relevant differences between cross-pin femoral fixation versus metal interference screw fixation [
Despite the ubiquitous use of cross-pin femoral fixation, there have been numerous intraoperative as well as postoperative complications reported in the literature. Cross-pin femoral fixation devices such as RigidFix have been associated with a variety of complications ranging from lateral pin slip [
There has been only one previously reported case of Bio-TransFix pin breakage with resultant clinical complications. Pelfort et al. [
Although the literature has not shown a definitive correlation between intraoperative technique and complications arising from bioabsorbable cross-pins, we feel that there are numerous technical considerations with regard to this type of femoral fixation. For the Bio-TransFix implant, our recommendations extend to taking measures to ensure that the implant is not broken intraoperatively as well as confirming complete seating of the implant once inserted. In the case report presented, it is plausible that our implant malfunction was the result of intra-operative difficulties. Our experience with this implant has shown that, during insertion, the wire or implant may break if there is an alignment mismatch. The bioabsorbable implant has a low resistance to tensile forces, and it may break if it is not inserted parallel to the nitinol wire. To prevent breakage of the implant, we recommend that retrieval of the nitinol wire from the lateral to medial femoral cortex be done in line with the drilled pin using a smooth, straight motion to avoid causing any kinks in the wire. The wire should be held as taut as possible in the same direction of the pin. Once the wire has been inserted, the implant should be tapped in the same orientation as the wire in a gradual stepwise manner. Kocher clamps should be attached to both sides of the wire, with one clamp attached near the implant inserter approximately 1 cm from the distal end of the slot in the inserter. The wire should be pulled from the medial side until the clamp touches the distal end of the slot and can no longer be advanced. The implant should then be gently tapped along the wire, again taking care to ensure proper orientation. This will recreate the distance between the clamp and the distal end of the slot. The medial side of the wire should then be pulled until the clamp advances to the end of the slot. Repeat these steps until the inserter bottoms out to the marking (on the inserter) near the skin as noted before. It is important not to tap beyond this marking as the implant will no longer advance and may break inside the bone resulting in post-operative migration. Steps should also be taken to ensure that there has been complete seating of the implant. The measurements off the reamer, broach, and the implant inserter should all be confirmed to be the same. Once the implant has been inserted, the lateral cortex should be digitally palpated.
Although the use of the bio-absorbable cross-pins has received considerable attention as a means of femoral fixation for anterior cruciate reconstruction, case series, and imaging studies have shown that a significant number of cross-pins can fracture and migrate with a potential for resultant clinical complications. Due to the asymptomatic or nonspecific nature of these complications, imaging studies are an integral part of patient management. Our case report illustrates the common phenomenon of implant breakage with a relatively rare complication of iliotibial band friction syndrome. It is possible that this complication was due to a combination of inherent implant failure and intra-operative difficulties. Given our experience and review of the literature, we feel that is it critical to be aware of the intra-operative difficulties that can be associated with this implant and encourage a low threshold for suspicion of pin breakage and migration when patients present with clinical complaints after ACL reconstruction. While the use of X-rays may serve as an initial screening modality to demonstrate pin breakage in these patients, the use of magnetic resonance imaging serves as a better imaging modality as it can not only diagnose fractured cross-pins but also reveal any surrounding soft tissue findings such as edema, IT band syndrome as well as provide information on state of the ACL graft. Patients with complications associated with cross-pin breakage and migration will often have complete resolution of symptoms once the offending fragment is surgically removed.