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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

Graphic depictions of various femoral attachments with the model medial patellofemoral ligament (MPFL) fixed at different knee flexion angles. For grafts fixed at >45° of knee flexion, substantial variation in graft lengths occur during the 0° to 30° range if the femoral attachment is not exactly at the Schottle point. As the MPFL is most important during the first 30° of flexion, deviations from proper kinematics will have significant clinical implications.
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fig6-2325967115569198: Graphic depictions of various femoral attachments with the model medial patellofemoral ligament (MPFL) fixed at different knee flexion angles. For grafts fixed at >45° of knee flexion, substantial variation in graft lengths occur during the 0° to 30° range if the femoral attachment is not exactly at the Schottle point. As the MPFL is most important during the first 30° of flexion, deviations from proper kinematics will have significant clinical implications.

Mentions: Our findings indirectly support securing the graft in the 30° to 45° range. The basis for this recommendation is established from prior research, which suggests that (1) the MPFL is the most important patellar stabilizer during the first 30° of knee flexion until the patella engages the trochlear groove,1,5 (2) overtightening the graft in extension results in iatrogenic medial subluxation of the patella, and (3) overtightening the graft in flexion results in loss of flexion and chondrosis.6,8,16,25,28 By examining the line graphs, if the graft is secured in more than 45° of knee flexion, the graft demonstrates significant variability in length during the 0° to 30° flexion range if the femoral attachment is not exactly at the Schottle point (Figure 6). In other words, fixing the graft at greater than 45° of knee flexion will magnify any mistakes in location and creates additional difficulty in maintaining appropriate graft kinematics when it is most important for patellar stability (ie, from 0° to 30° of knee flexion). Even if the femoral attachment is not exactly at the Schottle point, fixing the graft in the 30° to 45° range will minimize any deleterious effect.


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)

Graphic depictions of various femoral attachments with the model medial patellofemoral ligament (MPFL) fixed at different knee flexion angles. For grafts fixed at >45° of knee flexion, substantial variation in graft lengths occur during the 0° to 30° range if the femoral attachment is not exactly at the Schottle point. As the MPFL is most important during the first 30° of flexion, deviations from proper kinematics will have significant clinical implications.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

fig6-2325967115569198: Graphic depictions of various femoral attachments with the model medial patellofemoral ligament (MPFL) fixed at different knee flexion angles. For grafts fixed at >45° of knee flexion, substantial variation in graft lengths occur during the 0° to 30° range if the femoral attachment is not exactly at the Schottle point. As the MPFL is most important during the first 30° of flexion, deviations from proper kinematics will have significant clinical implications.
Mentions: Our findings indirectly support securing the graft in the 30° to 45° range. The basis for this recommendation is established from prior research, which suggests that (1) the MPFL is the most important patellar stabilizer during the first 30° of knee flexion until the patella engages the trochlear groove,1,5 (2) overtightening the graft in extension results in iatrogenic medial subluxation of the patella, and (3) overtightening the graft in flexion results in loss of flexion and chondrosis.6,8,16,25,28 By examining the line graphs, if the graft is secured in more than 45° of knee flexion, the graft demonstrates significant variability in length during the 0° to 30° flexion range if the femoral attachment is not exactly at the Schottle point (Figure 6). In other words, fixing the graft at greater than 45° of knee flexion will magnify any mistakes in location and creates additional difficulty in maintaining appropriate graft kinematics when it is most important for patellar stability (ie, from 0° to 30° of knee flexion). Even if the femoral attachment is not exactly at the Schottle point, fixing the graft in the 30° to 45° range will minimize any deleterious effect.

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