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Troubleshooting the Femoral Attachment During Medial Patellofemoral Ligament Reconstruction: Location, Location, Location.

Burrus MT, Werner BC, Conte EJ, Diduch DR - Orthop J Sports Med (2015)

Bottom Line: Appropriately, significant research has been undertaken regarding graft biomechanics and techniques, as intraoperative errors in graft placement often result in poor patient outcomes.Using a sawbones knee model, the concepts of an MPFL graft that is "high and tight" or "low and loose" are presented, with the goal of providing physicians with intraoperative tools to adjust an incorrectly placed femoral MPFL attachment.This model is also used to justify the recommendation of graft fixation in 30° to 45° of knee flexion.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.

ABSTRACT
The medial patellofemoral ligament (MPFL) has been recognized as an important soft tissue restraint in preventing lateral patellar translation. As many patients with acute or chronic patellar instability will have a deficient MPFL, reconstruction of this ligament is becoming more common. Appropriately, significant research has been undertaken regarding graft biomechanics and techniques, as intraoperative errors in graft placement often result in poor patient outcomes. Although the research has not answered all of the dilemmas encountered during reconstruction, publications consistently emphasize the importance of re-establishing an anatomic femoral attachment. The purpose of this study was to briefly review the current literature on MPFL reconstruction. Graft selection and patellar graft attachment and fixation are discussed, but the main focus is the femoral attachment as this is where most errors are seen and, unfortunately, where getting it right appears to matter the most. Using a sawbones knee model, the concepts of an MPFL graft that is "high and tight" or "low and loose" are presented, with the goal of providing physicians with intraoperative tools to adjust an incorrectly placed femoral MPFL attachment. This model is also used to justify the recommendation of graft fixation in 30° to 45° of knee flexion.

No MeSH data available.


Related in: MedlinePlus

Sawbones and corresponding graphic depiction of how a poorly placed proximal medial patellofemoral ligament (MPFL) femoral attachment creates too much tension in the graft during knee flexion, as a longer graft would be required to maintain the same amount of tension. The red circle matches the radius of the graft at full extension. The blue line represents the distance from the femoral insertion to the patellar insertion. In other words, if the blue line ends outside of the red circle, then the graft would be too tight. Thus, “high and tight.”
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fig4-2325967115569198: Sawbones and corresponding graphic depiction of how a poorly placed proximal medial patellofemoral ligament (MPFL) femoral attachment creates too much tension in the graft during knee flexion, as a longer graft would be required to maintain the same amount of tension. The red circle matches the radius of the graft at full extension. The blue line represents the distance from the femoral insertion to the patellar insertion. In other words, if the blue line ends outside of the red circle, then the graft would be too tight. Thus, “high and tight.”

Mentions: Based on the above data, recommendations were developed to assist surgeons in making intraoperative adjustments if the graft becomes too tight or too loose during knee flexion. As shown in Figure 4, if the guide pin is attached to the femur at a location proximal to the Schottle point, then the suture has positive length changes as the knee is brought into flexion (ie, the distance between the patellar and femoral attachments increases). This is due to the cam shape of the distal femur with the long anterior to posterior length of the femoral condyles. Thus, the graft will become too tight when the knee is brought into flexion. A simple way to recall this relationship is “high and tight,” as a proximal or high pin position results in a graft tight in flexion. Conversely, if the guide pin is attached to the femur at a location distal to the Schottle point, then the graft has negative length changes as the knee is brought into flexion (ie, the distance between the patellar and femoral attachments decreases) (Figure 5). Thus, the graft will become too loose when the knee is brought into flexion. A simple way to recall this relationship is “low and loose.” Intraoperatively, a commonly used technique to measure graft tension is to loop the 2 free graft ends around the guide pin in the femur and take the knee through a full ROM. As light tension is applied, changes in length are observed. The surgeon can also manually assess patella translation and stability. Thus, the surgeon can roughly gauge graft tension and, based on the above concepts, make femoral attachment adjustments as needed.


Troubleshooting the Femoral Attachment During Medial Patellofemoral Ligament Reconstruction: Location, Location, Location.

Burrus MT, Werner BC, Conte EJ, Diduch DR - Orthop J Sports Med (2015)

Sawbones and corresponding graphic depiction of how a poorly placed proximal medial patellofemoral ligament (MPFL) femoral attachment creates too much tension in the graft during knee flexion, as a longer graft would be required to maintain the same amount of tension. The red circle matches the radius of the graft at full extension. The blue line represents the distance from the femoral insertion to the patellar insertion. In other words, if the blue line ends outside of the red circle, then the graft would be too tight. Thus, “high and tight.”
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2 - License 3
Show All Figures
getmorefigures.php?uid=PMC4555580&req=5

fig4-2325967115569198: Sawbones and corresponding graphic depiction of how a poorly placed proximal medial patellofemoral ligament (MPFL) femoral attachment creates too much tension in the graft during knee flexion, as a longer graft would be required to maintain the same amount of tension. The red circle matches the radius of the graft at full extension. The blue line represents the distance from the femoral insertion to the patellar insertion. In other words, if the blue line ends outside of the red circle, then the graft would be too tight. Thus, “high and tight.”
Mentions: Based on the above data, recommendations were developed to assist surgeons in making intraoperative adjustments if the graft becomes too tight or too loose during knee flexion. As shown in Figure 4, if the guide pin is attached to the femur at a location proximal to the Schottle point, then the suture has positive length changes as the knee is brought into flexion (ie, the distance between the patellar and femoral attachments increases). This is due to the cam shape of the distal femur with the long anterior to posterior length of the femoral condyles. Thus, the graft will become too tight when the knee is brought into flexion. A simple way to recall this relationship is “high and tight,” as a proximal or high pin position results in a graft tight in flexion. Conversely, if the guide pin is attached to the femur at a location distal to the Schottle point, then the graft has negative length changes as the knee is brought into flexion (ie, the distance between the patellar and femoral attachments decreases) (Figure 5). Thus, the graft will become too loose when the knee is brought into flexion. A simple way to recall this relationship is “low and loose.” Intraoperatively, a commonly used technique to measure graft tension is to loop the 2 free graft ends around the guide pin in the femur and take the knee through a full ROM. As light tension is applied, changes in length are observed. The surgeon can also manually assess patella translation and stability. Thus, the surgeon can roughly gauge graft tension and, based on the above concepts, make femoral attachment adjustments as needed.

Bottom Line: Appropriately, significant research has been undertaken regarding graft biomechanics and techniques, as intraoperative errors in graft placement often result in poor patient outcomes.Using a sawbones knee model, the concepts of an MPFL graft that is "high and tight" or "low and loose" are presented, with the goal of providing physicians with intraoperative tools to adjust an incorrectly placed femoral MPFL attachment.This model is also used to justify the recommendation of graft fixation in 30° to 45° of knee flexion.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.

ABSTRACT
The medial patellofemoral ligament (MPFL) has been recognized as an important soft tissue restraint in preventing lateral patellar translation. As many patients with acute or chronic patellar instability will have a deficient MPFL, reconstruction of this ligament is becoming more common. Appropriately, significant research has been undertaken regarding graft biomechanics and techniques, as intraoperative errors in graft placement often result in poor patient outcomes. Although the research has not answered all of the dilemmas encountered during reconstruction, publications consistently emphasize the importance of re-establishing an anatomic femoral attachment. The purpose of this study was to briefly review the current literature on MPFL reconstruction. Graft selection and patellar graft attachment and fixation are discussed, but the main focus is the femoral attachment as this is where most errors are seen and, unfortunately, where getting it right appears to matter the most. Using a sawbones knee model, the concepts of an MPFL graft that is "high and tight" or "low and loose" are presented, with the goal of providing physicians with intraoperative tools to adjust an incorrectly placed femoral MPFL attachment. This model is also used to justify the recommendation of graft fixation in 30° to 45° of knee flexion.

No MeSH data available.


Related in: MedlinePlus