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A Magnetic Resonance Imaging Study of the Significance of the Distal Femoral Physis During Medial Patellofemoral Ligament Reconstruction.

Greenrod W, Cox J, Astori I, Baulch J, Williams J - Orthop J Sports Med (2013)

Bottom Line: Results are plotted against age and compared as quartile ranges.The femoral insertion of the MPFL was found to be distal to the distal femoral physis in all patients by an average of 10 mm (range, 2-16 mm).However, in children older than 10 years, a 20-mm screw, from the anatomic MPFL insertion and directed 45° distally oblique, should be safe in 98% of patients.

View Article: PubMed Central - PubMed

Affiliation: Mater Children's Hospital, Brisbane, Queensland, Australia. ; School of Medicine, University of Queensland, Brisbane, Queensland, Australia.

ABSTRACT

Background: Medial patellofemoral ligament (MPFL) reconstruction in adults often utilizes screw fixation in the distal femur. The aim was to define the safety of similar fixation in young patients, with respect to their open physis.

Purpose: To define the age-related relationship between the femoral insertion of the MPFL and the medial aspect of the distal femoral physis on magnetic resonance imaging (MRI) scans. The study investigates whether screw fixation at this point is safe with respect to patient age and screw inclination.

Study design: Cross-sectional study.

Methods: Retrospective review of the MRI scans of 159 skeletally immature patients. The femoral insertion of the MPFL was defined with respect to the distal femoral physis. The predicted paths of 2-cm screw fixation were simulated both parallel to the joint line and 45° distally oblique; physeal and joint penetration were noted when present. Results are plotted against age and compared as quartile ranges.

Results: The femoral insertion of the MPFL was found to be distal to the distal femoral physis in all patients by an average of 10 mm (range, 2-16 mm). The mean distance increases slightly with age in a nonlinear relationship (r = 0.51, P < .001) from 9 mm at age 10 years to 12 mm by age 16 years. For the classic, parallel screw, the risk of physeal breach is high for all age groups (mean, 64%). For the novel, oblique screw, joint penetration and physeal breach were less prevalent (mean, 13%), and importantly, the vast majority of these breaches were in younger children (age <9 years 9 months). With oblique screws, older children were at significantly lower risk than younger children (<3% vs 48%; P < .001).

Conclusion: This study accurately defines the relationship between the femoral insertion of the MPFL and the distal femoral physis in children and adolescents. A high risk of potentially poor outcomes was found during anatomic reconstruction of the MPFL in children utilizing classic (parallel) screw fixation, irrespective of age. However, in children older than 10 years, a 20-mm screw, from the anatomic MPFL insertion and directed 45° distally oblique, should be safe in 98% of patients.

No MeSH data available.


Projected screw paths. (A) The distal aspect of the femoral condyle is marked, and a parallel line was drawn through the medial patellofemoral ligament (MPFL) insertion point. (B) The classic screw path is drawn along the parallel line, while (C) the novel screw path is drawn 45° distally oblique.
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fig2-2325967113502638: Projected screw paths. (A) The distal aspect of the femoral condyle is marked, and a parallel line was drawn through the medial patellofemoral ligament (MPFL) insertion point. (B) The classic screw path is drawn along the parallel line, while (C) the novel screw path is drawn 45° distally oblique.

Mentions: A line was drawn through the most distal aspect of the medial and lateral femoral condyles, and a second line was drawn parallel to this but through the MPFL insertion point (Figure 2). The projected path of a fixation screw (20 mm in length) was then drawn from the MPFL insertion point. The classic screw path was drawn along a parallel line. Our novel screw path was then drawn 45° distally oblique to the parallel line (Figure 2). If the projected screw crossed the physis, a physeal breach was recorded. Similarly, if the projected screw crossed the bony cortex of the medial femoral condyle or the intercondylar notch, joint penetration was recorded.


A Magnetic Resonance Imaging Study of the Significance of the Distal Femoral Physis During Medial Patellofemoral Ligament Reconstruction.

Greenrod W, Cox J, Astori I, Baulch J, Williams J - Orthop J Sports Med (2013)

Projected screw paths. (A) The distal aspect of the femoral condyle is marked, and a parallel line was drawn through the medial patellofemoral ligament (MPFL) insertion point. (B) The classic screw path is drawn along the parallel line, while (C) the novel screw path is drawn 45° distally oblique.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4555493&req=5

fig2-2325967113502638: Projected screw paths. (A) The distal aspect of the femoral condyle is marked, and a parallel line was drawn through the medial patellofemoral ligament (MPFL) insertion point. (B) The classic screw path is drawn along the parallel line, while (C) the novel screw path is drawn 45° distally oblique.
Mentions: A line was drawn through the most distal aspect of the medial and lateral femoral condyles, and a second line was drawn parallel to this but through the MPFL insertion point (Figure 2). The projected path of a fixation screw (20 mm in length) was then drawn from the MPFL insertion point. The classic screw path was drawn along a parallel line. Our novel screw path was then drawn 45° distally oblique to the parallel line (Figure 2). If the projected screw crossed the physis, a physeal breach was recorded. Similarly, if the projected screw crossed the bony cortex of the medial femoral condyle or the intercondylar notch, joint penetration was recorded.

Bottom Line: Results are plotted against age and compared as quartile ranges.The femoral insertion of the MPFL was found to be distal to the distal femoral physis in all patients by an average of 10 mm (range, 2-16 mm).However, in children older than 10 years, a 20-mm screw, from the anatomic MPFL insertion and directed 45° distally oblique, should be safe in 98% of patients.

View Article: PubMed Central - PubMed

Affiliation: Mater Children's Hospital, Brisbane, Queensland, Australia. ; School of Medicine, University of Queensland, Brisbane, Queensland, Australia.

ABSTRACT

Background: Medial patellofemoral ligament (MPFL) reconstruction in adults often utilizes screw fixation in the distal femur. The aim was to define the safety of similar fixation in young patients, with respect to their open physis.

Purpose: To define the age-related relationship between the femoral insertion of the MPFL and the medial aspect of the distal femoral physis on magnetic resonance imaging (MRI) scans. The study investigates whether screw fixation at this point is safe with respect to patient age and screw inclination.

Study design: Cross-sectional study.

Methods: Retrospective review of the MRI scans of 159 skeletally immature patients. The femoral insertion of the MPFL was defined with respect to the distal femoral physis. The predicted paths of 2-cm screw fixation were simulated both parallel to the joint line and 45° distally oblique; physeal and joint penetration were noted when present. Results are plotted against age and compared as quartile ranges.

Results: The femoral insertion of the MPFL was found to be distal to the distal femoral physis in all patients by an average of 10 mm (range, 2-16 mm). The mean distance increases slightly with age in a nonlinear relationship (r = 0.51, P < .001) from 9 mm at age 10 years to 12 mm by age 16 years. For the classic, parallel screw, the risk of physeal breach is high for all age groups (mean, 64%). For the novel, oblique screw, joint penetration and physeal breach were less prevalent (mean, 13%), and importantly, the vast majority of these breaches were in younger children (age <9 years 9 months). With oblique screws, older children were at significantly lower risk than younger children (<3% vs 48%; P < .001).

Conclusion: This study accurately defines the relationship between the femoral insertion of the MPFL and the distal femoral physis in children and adolescents. A high risk of potentially poor outcomes was found during anatomic reconstruction of the MPFL in children utilizing classic (parallel) screw fixation, irrespective of age. However, in children older than 10 years, a 20-mm screw, from the anatomic MPFL insertion and directed 45° distally oblique, should be safe in 98% of patients.

No MeSH data available.