Medial Patellofemoral Ligament Origin Research Articles

The Schöttle Point Is Consistently Located Distal to the Medial Femoral Physis in Pediatric Patients: A Digitally Reconstructed Radiographic Study

Background: Significant controversy surrounds ideal tunnel position for medial patellofemoral ligament (MPFL) reconstruction (MPFLR) in the pediatric setting. The start point for femoral tunnel positioning (the Schöttle point) relative to the distal medial femoral physis is not well defined. Previous studies provide conflicting data regarding position of the MPFL origin and the Schöttle point relative to the distal femoral physis. Hypothesis: The Schöttle point would be consistently distal to the distal medial femoral physis. Study Design: Descriptive laboratory study. Methods: The institutional picture archiving and communication system was queried for computed tomography (CT) imaging studies of pediatric knees. Data were imported to an open-source image computing platform. True lateral digitally reconstructed radiographs and 3-dimensional (3D) renderings were generated, and the Schöttle point was registered in 3D space. Then, 3D distance measurements were obtained from the Schöttle point to the distal medial femoral physis. Results: A total of 49 pediatric knee CT scans were included. Mean age was 13.0 ± 2.3 years. Mean minimum distance from the medial physis to the Schöttle point was 9.9 ± 3.0 mm (range, 3.4-16.1 mm). In 49 of 49 cases (100%), the Schöttle point was distal to the physis. Using a 6-mm reaming diameter would result in 3 of 49 (6%) femurs having violation of the distal medial femoral physis. Moving the start point 3 mm distally would result in 0 of 49 (0%) sustaining physeal injury. Conclusion/Clinical Relevance: The Schöttle point is consistently distal to the distal medial femoral physis. The mean minimum distance from the Schöttle point to the physis on the medial cortex is 9.9 mm. The Schöttle point provides a safe and reliable radiographic landmark for pediatric MPFLR, although reaming diameter should be considered.

CORR Synthesis: Can Guided Growth for Angular Deformity Correction Be Applied to Management of Pediatric Patellofemoral Instability?

CORR Synthesis: Can Guided Growth for Angular Deformity Correction Be Applied to Management of Pediatric Patellofemoral Instability?

Relationship of the Medial Patellofemoral Ligament Origin on the Distal Femur to the Distal Femoral Physis: A Systematic Review

Background: The relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis has been reported in multiple studies. Purpose: To determine the distance from the MPFL central origin on the distal femur to the medial distal femoral physis in skeletally immature participants. Study Design: Systematic review. Methods: A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Multiple databases were searched for studies investigating the anatomic origin of the MPFL on the distal femur and its relationship to the medial distal femoral physis in skeletally immature participants. Study methodological quality was analyzed with the Anatomical Quality Assessment tool, with studies categorized as low risk, high risk, or unclear risk of bias. Continuous variable data were reported as mean ± SD. Categorical variable data were reported as frequency with percentage. Results: Seven articles were analyzed (298 femurs, 53.7% male patients; mean age, 11.7 ± 3.4 years). There was low risk of bias based on the Anatomical Quality Assessment tool. The distance from the MPFL origin to the distal femoral physis ranged from 3.7 mm proximal to the physis to 10.0 mm distal to the physis in individual studies. Six of 7 studies reported that the MPFL origin on the distal femur lies distal to the medial distal femoral physis in the majority of specimens. The MPFL originated distal to the medial distal femoral physis in 92.8% of participants at a mean distance of 6.9 ± 2.4 mm. Conclusion: The medial patellofemoral ligament originates distal to the medial distal femoral physis in the majority of cases at a mean proximal-to-distal distance of 7 mm distal to the physis. However, this is variable in the literature owing to study design and patient age and sex.

QUADRICEP TENDON TURNDOWNS FOR MPFL RECONSTRUCTION: AN ANATOMICAL DIFFERENCE BETWEEN THE ORIGINS OF THE QUADRICEP TENDON AND MPFL ON THE PATELLA

Background: Quadriceps tendon (QT) turndowns are an alternative method for medial patellofemoral ligament (MPFL) reconstruction, with several distinct advantages: 1. Avoids the use of patella bone tunnels, which have been associated with patella fracture, 2. Avoids the use of separate incision for hamstring tendon harvest, and 3. Avoids the use of allograft tissue, which adds a significant cost. The disadvantage of the Quad Tendon graft is that the most distal reflection point on the patella may not duplicate the patella origin of the native MPFL. The purpose of this study was to determine whether a QT graft for MPFL reconstruction is anatomically analogous to the native MPFL origin in a skeletally immature population. Methods: Three skeletally immature cadaveric knee specimens (ages 10 and 11, 11) were dissected to reveal the MPFL and QT origins on the patella. The proximal and distal extent of the MPFL was marked on the medial border of the patella. The medial aspect of the quad tendon was reflected as far as possible in both a medial and distal position on the patella, to function as the MPFL graft. The distance was measured between the midpoint of the patellar origin of the MPFL in the coronal plane, and the most distal aspect of the patellar origin of the reflected quad tendon. Results: In the 10, 11, and 11 year-old specimens, the distance between the midpoint of MPFL patellar origin and the QT patellar origin was 3.4 cm, 4.3, and 3.7 mm. In all cases, the QT reflected origin was at least 7 mm anterior to the to native MPFL origin on the medial border of the patella. Conclusion: A disparity exists between the patellar origin of the MPFL and the patellar origin of the quad tendon, with the patellar origin of the MPFL being more medial, more distal, and more posterior than the reflected patellar origin of the QT graft. Surgeons performing MPFL reconstructions may find this anatomically valuable as they attempt to duplicate the normal anatomy of the patella stabilizers during surgical reconstruction. While the QT remains a good graft choice for MPFL reconstruction, attachment of the QT graft at the native origin of the MPFL may better reproduce the anatomy of the MPFL. Figures: [Figure: see text][Figure: see text]

Anisometry of Medial Patellofemoral Ligament Reconstruction in the Setting of Increased Tibial Tubercle–Trochlear Groove Distance and Patella Alta

To assess the impact elevated tibial tubercle-trochlear groove (TT-TG) distance and patella height, as measured by the Caton-Deschamps Index (CDI), have on the isometry of a reconstructed medial patellofemoral ligament (MPFL). Nine fresh-frozen cadaveric knees were placed on a custom testing fixture, with a fixed femur and a mobile tibia. A suture fixed to the MPFL origin on the patella and free to move at the Schöttle point on the femur represented a reconstructed MPFL. A local coordinate system was established, and retroreflective markers attached to the suture quantified MPFL length changes by use of a 3-dimensional motion capture system. The tubercle was transferred to create TT-TG distances of 20mm and 25mm and CDIs of 1.2 and 1.4 (patella alta). Recordings of the MPFL suture length change as the knee was brought through a range of motion were made using all combinations of tubercle anatomy in a randomized order for each specimen. A generalized estimating equation modeling technique was used to analyze and control for the clustered nature of the data. Knees with native tibial tubercle anatomy showed MPFL isometry through 20° to 70° range of motion. Tibial tubercle lateralization (increased TT-TG distance) significantly altered MPFL isometry with a TT-TG distance of 20mm(P < .0001). Patella alta significantly altered MPFL isometry with a CDI of 1.2 (P= .0182). The interaction of tibial tubercle lateralization combined with patella alta significantly increased the amount of anisometry seen in the reconstructed MPFL (P < .001). Increased tibial tubercle lateralization and patella alta produce anisometry in an MPFL reconstruction using currently recommended landmarks, leading to potentially increased graft tension and potential failure. Tibial tubercle transfer should be considered when performing an MPFL reconstruction for recurrent patellofemoral instability in the setting of significant patella alta and an elevated TT-TG distance-especially when both are present-because an isolated MPFL reconstruction will be prone to failure given the anisometry shown in this study.

Variation in the Medial Patellofemoral Ligament Origin in the Skeletally Immature Knee: An Anatomic Study

Background: The medial patellofemoral ligament (MPFL) is frequently reconstructed to treat recurrent patellar instability. The femoral origin of the MPFL is well described in adults but not in the skeletally immature knee. Purpose: To identify a radiographic landmark for the femoral MPFL attachment in the skeletally immature knee and study its relationship to the distal femoral physis. Study Design: Descriptive laboratory study. Methods: Thirty-six cadaveric specimens between 2 and 11 years old were dissected and examined (29 male and 7 female). Metallic markers were placed at the proximal and distal borders of the MPFL femoral origin footprint. Computed tomography scans with 0.625-mm slices in the axial, coronal, and sagittal planes were used to measure the maximum ossified height and ossified depth. The measurements were used to describe the position of the midpoint MPFL attachment with respect to the posterior-anterior and distal-proximal dimensions of the femoral condyle on the sagittal view and to describe the distance from the physis to the femoral origin of the MPFL. Results: In 23 of 36 specimens, the femoral origin of the MPFL was distal to the physis. Thirteen of the 36 specimens had an MPFL origin at or proximal to the physis, with a more proximal MPFL origin consistently seen in older specimens. The distance of the MPFL origin to the physis ranged from 15.1 mm distal to the physis to 8.3 mm proximal to the physis. The mean midpoint of the MPFL femoral origin was located 3.0 ± 5.5 mm distal to the physis for all specimens. For specimens aged <7 years, the mean MPFL origin was 4.7 mm distal to the physis, and for specimens aged ≥7 years, the mean MPFL origin was 0.8 mm proximal to the femoral physis. The MPFL origin was more proximal and anterior for those aged ≥7 years and more distal and posterior for those aged <7 years. Conclusion: Surgical reconstruction of the MPFL is a common treatment to restore patellar stability. There appears to be significant variability in the origin of the MPFL in skeletally immature specimens. This study demonstrated that the MPFL origin was more proximal and anterior with respect to the physis in the older age group. The MPFL origin footprint may be customized for different age groups. Clinical Relevance: This information shows anatomic variation of the MPFL origin with age, with older specimens having a footprint that was more proximal and anterior than younger specimens. Customization of the surgical technique might be considered based on patient age.

“Pin the Tail on the MPFL” Identification by Palpation - Results

Objectives:Medial patellofemoral ligament (MPFL) reconstruction has become increasingly popular to treat patellar dislocation. Studies have noted the importance of recovering the anatomic insertion of the MPFL and that reconstruction should be performed within 5mm of the native insertion site to avoid biomechanical complications. Currently radiographic imaging is used to locate the MPFL insertion site at Schottle’s point. This study investigated the viability of utilizing palpation to locate the MPFL insertion site for proper MPFL reconstruction.Methods:Thirty-eight patellofemoral specialists attending IPSG were selected to participate in this study with a mean of 15.9 years in practice (median 14, range 1-39). Using a single fresh-frozen human cadaveric knee, each specialist individually performed surface palpation of the anatomical landmarks and inserted a dissection pin at the purposed MPFL femoral insertion site. Radiographic images were taken of each pin placement. At conclusion, the cadaveric leg was dissected and forceps were placed at the distal and proximal end of the MPFL insertion with a dissection pin in the middle of the insertion and a radiographic image was taken of this. Images were analyzed using ImageJ software to determine the distance and angle from the MPFL insertion center to the specialist’s pin location.Results:Length and angle measurements were taken three times and averaged for each sample. The bridge of a forceps was utilized as a scale for the images (2.325 pixels/mm). Average distance was found to be 3.18 ± 2.55 mm with an average angle of 161.2 ± 74.4° relative to the anterior direction indicating 0°. Seven of thirty-eight (18%) samples were more than 5mm from the native insertion site.Conclusion:With an average pin displacement of 3.18mm, it was seen that most specialists could accurately determine MPFL insertion location accurately without the use of radiographic equipment. On average, the displacement angle of 161.2° indicates the pin was typically located more posterior than the MPFL insertion site. Seven measurements exceeded 5mm distance from the MPFL insertion, which would be concerning for biomechanical effects on the patellofemoral joint if the repair was placed at the pin location.Clinical Relevance:While experienced patellofemoral surgeons were able to identify femoral MPFL origin with reasonable accuracy by palpation, even experienced surgeons had inaccuracies that could compromise outcomes up to 18% of the time. For this reason we recommend the use of radiography along with appropriate exposure to assist in accurately identifying the anatomic femoral attachment of the MPFL during MPFL reconstruction.

Safe Drilling Paths in the Distal Femoral Epiphysis for Pediatric Medial Patellofemoral Ligament Reconstruction

Background: Anatomic surgical reconstruction of the medial patellofemoral ligament (MPFL) has been popularized for the treatment of recurrent patellar instability in the skeletally immature population. Previous anatomic studies have found that the femoral attachment point of the MPFL is very close to the distal femoral physis. Purpose: To establish the safe angles for drilling the distal femoral epiphysis for MPFL graft placement. Study Design: Descriptive laboratory study. Methods: A total of 23 cadaveric distal femoral epiphyses were scanned into high-resolution 3-dimensional images. Using computer-aided design, we identified and marked the femoral insertion site of the MPFL. Cylinders 8 mm in diameter were placed at varying angles to simulate the drill paths for placement of 6-mm interference screws with a 1-mm buffer. The distance from the MPFL footprint to where the tunnel first violated the physis, the intercondylar notch, or the distal cartilage was measured. We recorded the percentage of tunnels that caused violations before reaching 20 mm, the shortest length of a typical femoral tunnel socket. Results: Measurements indicated that 41% of tunnels angled distally less than 10° violated the physis, 40% of tunnels angled distally more than 10° but anteriorly less than 10° violated the notch, and 27% of tunnels angled distally and anteriorly more than 20° violated the distal femoral cartilage. At least 90% of the tunnels were safe at 20 mm when the drill was angled between 15° and 20° both anteriorly and distally. Conclusion: Because of the anatomy of the distal femoral physis, drilling into the epiphysis from the MPFL attachment site at improper trajectories risks damage to sensitive structures. Angling the drill to an acceptable degree distally and anteriorly leads to less risk to the physis and notch, respectively, but angling too much leads to risk to the distal femoral cartilage. Small variations in the sagittal plane were better tolerated than variations in the coronal plane, so we recommend that more attention be paid to the radiographic anteroposterior view intraoperatively. It is safest to angle the drill distally and anteriorly approximately 15° to 20° in each plane from the MPFL attachment site. Clinical Relevance: During drilling into the distal femoral epiphysis at the MPFL origin in skeletally immature patients, angling the drill appropriately 15° to 20° both distally and anteriorly minimizes damage to the physis, notch, and distal femoral cartilage.

Normal Parameters of the Skeletally Immature Knee: Developmental Changes on Magnetic Resonance Imaging.

A child's knee undergoes significant morphologic changes during development. Age-specific normal parameters have not been previously described. The purpose of this study was to delineate knee morphology changes that occur with maturation utilizing magnetic resonance imaging (MRI). A retrospective review of knee MRIs, ages 4 to 18 years, was performed using "normal" diagnosis codes, including: knee pain, plicae, septic arthritis, jumper's knee, growing pains, benign neoplasm, and osteomyelitis. Seventeen osseous parameters were measured, plus their cartilaginous counterparts, if different. Spearman ρ correlations were calculated between age and MRI measures. A total of 132 MR images were reviewed. Significant correlation with age was observed in all osseous measurements, except medial patellofemoral ligament (MPFL) insertion (P<0.05). Similarly, the cartilage measures demonstrated significant correlation with age, except the notch width index, MPFL insertion, and trochlear morphology. The magnitude of correlation was significantly different between the osseous and cartilage measures for all but 4 of the variables: anterior cruciate ligament (ACL) length and width, intercondylar width and tibial tubercle-trochlear groove (TT-TG) interval. Sex seems to affect ACL length, Insall-Salvati ratio, intercondylar width, and sulcus angle.The MPFL origin starts distal to the physis and moves proximal with age (ρ=0.33, P<0.001), when at age 7 years, it is located at or above the femoral physis. The mean ACL diameter grows from 6.5 to 9.8 mm. Cartilage sulcus angle remains consistently 150 degrees, and the TT-TG interval shifts from 6 to 12 mm with maturity. The normative data presented here demonstrates that maturity correlates well with the morphologic changes seen in most of the studied parameters. These data not only aid in the identification of the abnormal findings by sex and age, but also provides normal sizes of the ACL and location of insertion for the MPFL which can benefit surgical planning.

The relationship of the femoral physis and the medial patellofemoral ligament in children: a cadaveric study.

Patellar dislocations are common in skeletally immature athletes, and the medial patellofemoral ligament (MPFL) is an important primary restraint to lateral patellar translation. The relationship between the MPFL femoral origin footprint and femoral physis is unclear. The purpose of this study was to evaluate the MPFL femoral origin footprint and its relationship to the femoral physis in skeletally immature anatomic specimens. Six skeletally immature cadaver knee specimens were examined through gross dissection (group A: 1, 11, and 11 mo; and group B: 8, 10, and 11 y). Metallic markers were placed at the center of the MPFL femoral origin footprint. Computed tomography scans for each specimen were analyzed. The MPFL footprint width, and the vertical distances from the center and proximal extent of the MPFL footprint to the medial aspect of the physis were measured. The mean width of the MPFL femoral origin footprint was 0.70 cm (0.48 to 1.09 cm) and 1.12 cm (1.03 to 1.29 cm) for groups A and B, respectively. The mean distance from the center of the MPFL origin footprint to medial aspect of the distal femoral physis was 0.90 cm (0.52 to 1.30 cm) and 0.40 cm (0.00 to 0.86 cm) distal to the physis for groups A and B, respectively. The mean distance from the proximal extent of the MPFL origin footprint to the medial aspect of the femoral physis was -0.55 cm (-0.28 to -1.03 cm) and 0.16 cm (-0.34 to 0.64 cm) for groups A and B, respectively. All subjects were found to have a center of the MPFL origin footprint at or below the physis. The proximal extent of the MPFL origin footprint was found to extend above the physis in the 2 older specimens. The relationship of the MPFL origin footprint to the femoral physis in the skeletally immature is not well understood. These dissections may be useful to surgeons performing MPFL reconstructions in skeletally immature patients.

Simultaneous Medial and Lateral Patellofemoral Ligament Reconstruction for Combined Medial and Lateral Patellar Subluxation

Medial patellar subluxation (MPS) is a disabling, often iatrogenic patellar instability due to previous lateral release for patellar instability. Lateral release destabilizes the patella on the lateral side, worsening the initial lateral instability and causing MPS. MPS is poorly recognized and may range from subluxation to true dislocation. This report describes a technique developed in response to episodes of medial and lateral patellar subluxation after failed lateral release for patellar instability. The technique uses a graft that extends from the medial patellofemoral ligament origin through the quadriceps tendon to the lateral epicondyle, thereby reconstructing both the medial and lateral patellofemoral ligaments, as well as providing simultaneous stability to both the medial and lateral sides of the patella.

Metaphyseal Screw Migration After Medial Patellofemoral Ligament Reconstruction in a Skeletally Immature Patient: A Case Report.

Patellar instability is a common problem in the pediatric population and has an estimated annual incidence of forty-three in 100,0001. More recently, the rate of recurrent patellar instability in the pediatric population has been reported to be as high as 70%2. It is well known that the medial patellofemoral ligament (MPFL) is an important stabilizer of the patella and supplies between 50% and 60% of the restraining force to lateral patellar translation3-5. Localizing and recreating the anatomic femoral insertion of the MPFL is important for surgical treatment since malpositioned grafts can lead to patellofemoral overload or recurrent instability6. Locating the anatomic femoral position of the MPFL in adults has been simplified by utilizing radiographic osseous landmarks with intraoperative fluoroscopy7. In children, the exact location of the MPFL relative to the distal femoral physis remains controversial. Utilizing the principles of the perfect lateral radiograph described in a study by Schottle et al. in 20077, Shea et al.8 have suggested that the midsubstance of the MPFL origin lies just proximal to the distal femoral physis. However, a radiographic-based study by Nelitz et al.9 and a study by Ladd et al.10 based on magnetic resonance imaging (MRI) both concluded that the MPFL femoral insertion is located distal to the physis. Furthermore, an MRI study by Kepler et al.11 identified the MPFL insertion to be variable, with 86% attaching distal to the physis, 7% attaching on the physis, and 7% attaching proximal to the physis. These discordant results make it difficult to decide where the most appropriate “anatomic” location truly lies. This translates into some surgeons recommending femoral graft placement proximal to the physis, while other surgeons recommend placement distal to the physis. This becomes more …

Arthroscopic extraarticular reconstruction of the medial patellofemoral ligament with gracilis tendon autograft - surgical technique

The standard approach to reconstruct the medial patellofemoral ligament (MPFL) is by mini-open incision at its patellar insertion and femoral origin. At the medial patella rim, the MPFL insertion may be visualized in most cases by dissection during surgery. On the femur, it is more difficult to localize the MPFL remnants by a mini-open incision due to soft tissue covering the anatomical origin. Therefore, the femoral MPFL origin is usually identified by intraoperative lateral fluoroscopy. However, the insertion and origin of the MPFL at the patella and femur might be directly visualized using an arthroscopic extraarticular approach from the knee joint through a window of the synovial layer. This is especially helpful on the femoral side but also at the patella to find the individual anatomical MPFL footprints. Arthroscopic extraarticular reconstruction may then be performed using one additional medial mid-parapatellar portal. The major advantages of this technique are an individualized anatomical procedure, which is minimal invasive and cosmetically appealing. The aim of this study was to describe the arthroscopic extraarticular approach to the MPFL insertion at the patella and origin at the femur through synovial windows and to explain the procedure of arthroscopic MPFL reconstruction with a gracilis tendon autograft. Level of evidence Expert opinion, surgical technique, Level V.

The Relation of the Femoral Physis and the Medial Patellofemoral Ligament

The purpose of this study was to determine the origin of the medial patellofemoral ligament (MPFL) relative to the distal femoral physis by use of an indirect radiologic method. Twenty radiographs from adolescent male and female subjects (10 samples from each group) were used. The subjects studied were all skeletally immature, with an open distal femoral physis. The radiographic technique described by Schöttle et al. was used to identify the origin of the MPFL. Imaging software was used to determine the approximate distance of the MPFL origin relative to the open growth plate of the subjects involved. In all 20 radiographs the medial physis was found to be distal to the average MPFL insertion point. The mean location for the female physis was 2.7 +/- 1.1 mm distal to the MPFL origin. The mean location for the male physis was 4.6 +/- 2.4 mm distal to the MPFL origin. Based on an indirect radiographic technique, we found that the origin of the MPFL is just proximal to the femoral physis. This information may be useful when planning medial retinacular surgical procedures in skeletally immature athletes to help avoid clinically significant physeal injury.

A mini-invasive adductor magnus tendon transfer technique for medial patellofemoral ligament reconstruction: a technical note

Patellar dislocations are associated with injuries to the medial patellofemoral ligament (MPFL). Several techniques for MPFL reconstruction have been recently published with some disadvantages involved, including large skin incisions and donor site morbidity. Arthroscopic stabilizing techniques carry the potential of inadequate restoration of MPFL function. We present a minimally invasive technique for MPFL reconstruction using adductor magnus tendon autograft. This technique is easily performed, safe, and provides a stabilizing effect equal to current MPFL reconstructions. Skin incision of only 3-4 cm is located at the level of the proximal half of the patella. After identifying the distal insertion of the adductor magnus tendon, a tendon harvester is introduced to harvest the medial two-thirds of the tendon, while the distal insertion is left intact. The adductor magnus tendon is cut at 12-14 cm from its distal insertion and transferred into the patellar medial margin. Two suture anchors are inserted through the same incision at the superomedial aspect of the patella in the anatomic MPFL origin. The graft is tightened at 30 degrees knee flexion. Aftercare includes 4 weeks of brace treatment with restricted range of motion.