Anatomic study of the attachment of the medial patellofemoral ligament and its characteristic relationships to the vastus intermedius

Evolution of the term "epicondyle of the femur": Revisiting the anatomical and surgical literature

The femoral epicondyle is an anatomical bony landmark essential for surgeons and anatomists, but there are discrepancies between the two fields when using this term. In current orthopedic surgery, it commonly denotes the small bony prominence of the femoral condyle. Given the derivation, "epicondyle" should be a region projecting laterally from the articular surface rather than a point. These discrepancies in usage are found not only between the fields but also in the literature. This article reviews the narrative definition of "epicondyle of the femur" in surgery and the evolution of the term in anatomy. The outcomes of the review suggest a relationship between the differing perceptions of the epicondyle and the evolution of the term. In reports of studies related to the epicondyle, it is strongly recommended that the definition of the word is clearly stated, with an understanding of its evolution.

Radiographic Landmark Measurements for the Femoral Footprint of the Medial Patellofemoral Complex May Be Affected by Visible Femoral Shaft Length on Lateral Knee Radiographs

PURPOSE

To assess the effect of visible femoral shaft length on the accuracy of radiographic landmarks of the medial patellofemoral complex (MPFC).

METHODS

In 9 cadaveric knees, the MPFC footprint was exposed on the medial femur, and its proximal and distal boundaries were marked. Lateral fluoroscopic images of the knee were assessed in 1-cm length increments, beginning 1 cm proximal to the medial condyle and continuing proximally to 8 cm. The MPFC midpoint was described on each image relative to the posterior cortical line of the femur and a line perpendicular to this line through the proximal margin of the medial condyle. In addition, the MPFC midpoint was assessed relative to a line from the proximal posterior cortex to the midpoint of Blumensaat line.

RESULTS

Using the posterior cortical line as a reference, the MPFC radiographic landmark moved anteriorly with decreasing visible femoral shaft on radiographs, particularly at 4 cm and less. However, no proximal-distal change was noted. Linear regression analysis demonstrated a relationship between visible femoral shaft and MPFC position on radiographs (R = 0.461, R2 = 0.212, B = -0.636, P < .001). For every centimeter decrease in the visible femoral shaft, the radiographic MPFC footprint moved anteriorly by 0.636 mm. Receiver operating characteristic curve analysis revealed that a minimum of 4 cm of femoral shaft on lateral radiographs is required for accurate MPFC footprint localization (area under the curve = 0.80; sensitivity = 76.7%; specificity = 69.0%; P < .001). In contrast, no anterior-posterior change was seen when referencing a line from the proximal posterior cortex to the midpoint of Blumensaat line.

CONCLUSIONS

When using the posterior cortical line to identify the midpoint of the MPFC, at least 4 cm of femoral shaft should be visible for accurate assessment. If less than 4 cm of shaft is visible, a line through the midpoint of Blumensaat line and the proximal posterior cortex can be used as an alternative method to estimate the position of the femoral footprint.

CLINICAL RELEVANCE

As fluoroscopy is frequently used intraoperatively for MPFC reconstruction, our findings may serve as a guide when assessing femoral tunnel placement on fluoroscopy.

Double-Limb Graft Versus Single-Limb Graft Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation: A Meta-analysis of Randomized Controlled Trials and Cohort Studies

BACKGROUND

The medial patellofemoral ligament (MPFL) is the most important stabilizer of lateral dislocation of the patella. Single-limb (SL) and double-limb (DL) graft MPFL reconstructions have been increasingly used to treat recurrent patellar dislocations, but the clinical efficacy of SL versus DL graft MPFL reconstructions remains controversial owing to the inconsistent conclusions of previous studies.

PURPOSE

This study aimed to compare the clinical outcomes of SL and DL graft MPFL reconstructions for patients with recurrent patellar dislocation by conducting a meta-analysis of randomized controlled trials and cohort studies.

STUDY DESIGN

Meta-analysis; Level of evidence, 3.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for relevant studies. The retrieval time was up to July 25, 2022. Two evaluators independently screened the literature, extracted data, and assessed the methodological quality of the enrolled studies. Meta-analysis was conducted using RevMan 5.4 software.

RESULTS

A total of 4 randomized controlled trials and 3 cohort studies with 451 patients were included. The joint stability and functional scores in both groups improved significantly from baseline. When compared with SL graft reconstruction, DL graft reconstruction provided reduced recurrent instability (P = .01), anterior patella-related pain (P = .02), and patellar lateral shift rate (P = .02). Regarding functional recovery, patients undergoing DL graft reconstruction presented better scores on the Kujala (P < .001), Tegner (P = .009), and International Knee Documentation Committee (IKDC) (P < .001) but similar Lysholm scores as compared with SL graft reconstruction. No statistically significant difference was found between the techniques in the reduction of the patellar tilt angle, complications other than anterior patella-related pain, or postoperative pain.

CONCLUSION

When compared with SL graft MPFL reconstruction, DL graft MPFL reconstruction yielded better outcomes in terms of postoperative recurrent instability, anterior patella-related pain, patellar lateral shift rate, Kujala score, Tegner score, and IKDC score. The amount of high-quality evidence is insufficient, so this conclusion should be interpreted with caution.

Cadaveric Study to Define the Anatomy of the Medial Patellofemoral Ligament (MPFL) and Its Variant Patterns

BACKGROUND

The medial patellofemoral ligament (MPFL) is one of the major soft tissue stabilizers on the medial side of the knee joint, extending from the medial condyle of the femur to the medial aspect of the patella. Different kinds of literature described different sizes and different origins and insertions of MPFL. Injury of MPFL causes patellar instability and dislocation. We reported the anatomy and morphology of MPFL and its implications in the repair of MPFL. The aim of the study was also to look at the variant forms of the MPFL.   Methodology: A total of 40 lower limbs fixed in formalin were dissected to study the MPFL of the knee. After reflecting the deep fascia and retinaculum on the medial side of the knee joint the MPFL was exposed. For better learning the lower medial part of vastus medialis was reflected, so that the part of MPFL undercover was exposed.

RESULTS

 Different forms of MPFL were seen like two straps 12.5%, broad rectangle 20%, and triangular shaped 67.5% MPFL. The origin of MPFL was found between the adductor tubercle and medial epicondyle of the femur and insertion was seen extending from the proximal medial half of the patella to the tendinous aponeurosis of vastus medialis obliquus (VMO) and vastus intermedius muscle (VIM).

CONCLUSIONS

This is the first study that described three variant patterns of MPFL in accordance with their morphological appearance. This knowledge will be helpful to the surgeons for easy identification and repair of the MPFL.

Biomechanical Comparison of 3 Medial Patellofemoral Complex Reconstruction Techniques Shows Medial Overconstraint but No Significant Difference in Patella Lateralization and Contact Pressure

PURPOSE

The purpose of this study was to investigate biomechanical differences of medial patellofemoral ligament (MPFL) reconstruction, medial quadriceps tendon femoral ligament (MQTFL) reconstruction, and a combination of these techniques to restore lateral patellar constraint and contact pressures.

METHODS

Eight fresh frozen cadaver knees were mounted to a custom jig with physiological quadriceps tendon loading. Flexion angles and contact pressure (CP) were dynamically measured using Tekscan® pressure sensors and Polhemus® Liberty 6 degree of freedom (6DOF) positioning sensors in the following conditions: 1) intact 2) MPFL and MQTFL deficient, 3) MPFL reconstructed, 4) Combined MPFL + MQTFL reconstructed, and 5) MQTFL reconstructed. Lateral patellar translation was tested using horizontally directed 30 N force applied at 30° of knee flexion. The knees were flexed in dynamic fashion, and CP values were recorded for 10°, 20°, 30°, 50°, 70°, and 90° degrees of flexion. Group differences were assessed with ANOVA's followed by pairwise comparisons with Bonferroni correction.

RESULTS

MPFL (P = .002) and combined MPFL/MQTFL (P = .034) reconstruction significantly reduced patellar lateralization from +19.28% (9.78%, 28.78%) in the deficient condition to -17.57% (-27.84%, -7.29%) and -15.56% (-33.61%, 2.30%), respectively. MPFL reconstruction was most restrictive and MQTFL reconstruction the least -7.29% (-22.01%, 7.45%). No significant differences were found between the three reconstruction techniques. Differences in CP between the three reconstruction techniques were not significant (<.02 MPa) at all flexion angles.

CONCLUSION

The present study found no significant difference for patellar lateralization and patellofemoral CP between MPFL, combined MPFL/MQTFL, and MQTFL reconstruction. All 3 techniques resulted in stronger lateral patellar constraint compared to the native state, while the MQTFL reconstruction emulated the intact state the closest.

CLINICAL RELEVANCE

Various surgical techniques for medial patellofemoral complex reconstruction can restore patellar stability with similar patellofemoral articular pressures.

Editorial Commentary: The Medial Patellofemoral Complex Is Composed of the Medial Patellofemoral Ligament and the Medial Quadriceps Tendon-Femoral Ligament: Do We Need to Reconstruct Both?

The medial patellofemoral ligament (MPFL) has been known as the primary soft-tissue restraint to lateral patellar translation. More recent anatomic studies have identified additional fibers that extend to the quadriceps tendon (medial quadriceps tendon-femoral ligament [MQTFL]), leading to the use of the term "medial patellofemoral complex" (MPFC) to describe the broad and variable attachment of this complex on the patella and quadriceps tendon. Whereas many techniques and outcomes of traditional MPFL reconstruction have been described, fewer reports exist on anatomic MPFC reconstruction to recreate both bundles of this complex. To date, the specific biomechanical roles of, and indications for, reconstruction of the MPFL versus MQTFL fibers have not been defined. One primary benefit of MQTFL reconstruction has been to avoid the risk of patella fracture, which is not obviated in the setting of concurrent patellar fixation when reconstructing both components of the MPFC. The risks and benefits comparing fixation on the patella, quadriceps tendon, or both with anatomic double-bundle reconstruction remain to be determined. Additional studies are needed to understand the differences between reconstructing the proximal and distal fibers of the MPFC with regard to graft length changes and femoral attachment sites, in order to optimally recreate the function of each graft bundle in the surgical treatment of patellar instability.

Combined Reconstruction of the Medial Patellofemoral Ligament and Medial Quadriceps Tendon Femoral Ligament in Skeletally Immature Patients

The medial patellofemoral ligament (MPFL) reconstruction is challenging in skeletally immature patients due to the anatomical particularities at this age. Recently, the medial quadriceps tendon femoral ligament (MQTFL) has received great interest for its ability to restrain the patella's instability along with MPFL. No gold-standard technique has been described so far to reconstruct both MPFL and MQTFL in skeletally immature patients. We present a technique to safely reconstruct the MPFL and the MQTFL in children and adolescents. The gracilis tendon autograft is harvested and passed through the medial collateral ligament as a pulley. The free ends of the graft are passed through the patella by an "L-shaped tunnel" and tied to itself. The other free end of the graft is pulled through the medial third of the quadriceps tendon and tied to itself to achieve tension. Our technique is reproducible, implant-free and avoids complications associated with femoral drilling and graft fixation. However no long-term follow-up results are available.

Radiographic Landmarks for the Femoral Attachment of the Medial Patellofemoral Complex: A Cadaveric Study

PURPOSE

To report the radiographic landmarks for the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the radiographic positions corresponding to the medial quadriceps tendon femoral ligament (MQTFL) and medial patellofemoral ligament (MPFL) fibers.

METHODS

In 8 unpaired cadaveric knees, the MPFC footprint was exposed on the medial femur, and the proximal and distal boundaries of the footprint were marked. Lateral fluoroscopic images of the knee were obtained and analyzed using Image J. The proximal boundary corresponding to the MQTFL, the MPFC midpoint, and distal boundary corresponding to the MPFL were described radiographically and compared for differences in position.

RESULTS

The proximal MQTFL footprint was 0.8 ± 0.6 mm anterior (P = .013) and 5.2 ± 1.8 mm proximal to the MPFC midpoint (P <.001), whereas the distal MPFL footprint was 0.8 ± 0.7 mm posterior (P = .012) and 5.9 ± 1.1 mm distal to the radiographic MPFC midpoint (P <.001). The radiographic point corresponding to the distal MPFL footprint was 0.8 ± 0.9 mm posterior (P = .011) and 11.1 ± 2.3 mm distal to the radiographic point of the proximal MQTFL footprint (P <.001). When using the point of intersection of the posterior cortical line and the proximal posterior condyle as a reference, 91.6% of all points correlating to the MQTFL, MPFC midpoint and MPFL, were within 10 mm in any direction from this radiographic landmark.

CONCLUSIONS

On fluoroscopic imaging, the proximal MQTFL and distal MPFL fibers had significantly different radiographic positions from the MPFC midpoint on the femur. These findings should be considered when reconstructing specific components of the MPFC.

CLINICAL RELEVANCE

As fluoroscopy is often used intraoperatively to guide graft placement, our findings may serve as a reference when differentiating the locations of the MPFL vs MQTFL on the femur for anatomic reconstruction.

Quantifying the Relationship Between the Medial Quadriceps Tendon-Femoral Ligament and Patellar Borders: A Pediatric Cadaveric Study

BACKGROUND

The medial patellofemoral complex (MPFC) is a structure composed of the medial quadriceps tendon-femoral ligament (MQTFL) superiorly and the medial patellofemoral ligament (MPFL) inferiorly. The pediatric MPFL anatomy has been well described, but the precise anatomy of the MQTFL has only recently been described and studied in skeletally immature patients.

PURPOSE

To describe the anatomic relationship between the MQTFL and its insertion on the quadriceps tendon and patella in pediatric specimens.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 22 pediatric cadaveric knee specimens were dissected to analyze attachment of the MQTFL to the quadriceps tendon and patella. Dissection was facilitated using lateral parapatellar arthrotomy followed by eversion of the extensor mechanism to evaluate MQTFL fibers from its undersurface.

RESULTS

The mean specimen age was 7.4 years. Specimens were divided based on age into a younger cohort (1-2 years), middle cohort (4-8 years), and older cohort (9-12 years). The quadriceps tendon attachment (QTA) of the MQTFL proximal to the patella extended a median of 5.0 mm in the younger cohort, 11.4 mm in the middle cohort, and 12.0 mm in the older cohort, with significant differences found between the younger and middle cohorts (P < .047) and the younger and older cohorts (P < .001). The QTA as a percentage of patellar articular height averaged 44.4% across all specimens. The vertical height of the patella measured a median of 14.0 mm, 22.3 mm, and 27.3 mm in the younger, middle, and older cohorts, respectively.

CONCLUSION

This study expands on the recently described anatomy of the pediatric MPFC to quantify the anatomic relationship between the MQTFL attachment to the quadriceps tendon and patella in a more clinically relevant cohort of donor specimens.

CLINICAL RELEVANCE

As access to pediatric cadaveric tissue is extremely limited, a better understanding of MPFC and MQTFL anatomy will support surgeons in preoperative planning and intraoperative considerations for their approach to MQTFL and MPFL reconstruction. This may facilitate improved anatomic surgical stabilization of the patellofemoral joint in pediatric patients.

Simultaneous Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament Reconstructions Using an Artificial Ligament for Lateral Patella Instability

Recent studies on the detailed anatomy of the medial patellar stabilizer have revealed that the medial patellofemoral ligament (MPFL) not only attaches to the patella but also has fibers that attach to the quadriceps muscle, known as the medial quadriceps tendon femoral ligament (MQTFL). Reconstruction of the medial stabilizer for patellar dislocation that includes both the MPFL and MQTFL may achieve better anatomical and physiological correction. In this Technical Note, we will describe a simultaneous reconstruction technique of the MPFL and MQTFL for patellar dislocation using an artificial ligament.

Utility of Diagnostic Ultrasound in the Assessment of Patellar Instability

Background

The use of imaging to diagnose patellofemoral instability is often limited by the inability to dynamically load the joint during assessment. Therefore, the diagnosis is typically based on physical examination using the glide test to assess and quantify lateral patellar translation. However, precise quantification with this technique remains difficult.

Purpose

To quantify patellar position using ultrasound imaging under dynamic loading conditions to distinguish between knees with and without medial patellofemoral complex (MPFC) injury.

Study Design

Controlled laboratory study.

Methods

In 10 cadaveric knees, the medial patellofemoral distance was measured to quantify patellar position from 0° to 40° of knee flexion at 10° increments. Knees were evaluated at each flexion angle under unloaded conditions and with 20 N of laterally directed force on the patella to mimic the glide test. Patellar position measurements were made on ultrasound images obtained before and after MPFC transection and compared for significant differences. To determine the ability of medial patellofemoral measurements to differentiate between MPFC-intact and MPFC-deficient states, area under the receiver operating characteristic (ROC) curve analysis and the Delong test were used. The optimal cutoff value to distinguish between the deficient and intact states was determined using the Youden J statistic.

Results

A significant increase in medial patellofemoral distance was observed in the MPFC-deficient state as compared with the intact state at all flexion angles (P = .005 to P < .001). When compared with the intact state, MPFC deficiency increased medial patellofemoral distance by 32.8% (6 mm) at 20° of knee flexion under 20-N load. Based on ROC analysis and the J statistic, the optimal threshold for identifying MPFC injury was 19.2 mm of medial patellofemoral distance at 20° of flexion under dynamic loading conditions (area under the ROC curve = 0.93, sensitivity = 77.8%, specificity = 100%, accuracy = 88.9%).

Conclusion

Using dynamic ultrasound assessment, we found that medial patellofemoral distance significantly increases with disruption of the MPFC.

Clinical Relevance

Dynamic ultrasound measurements can be used to accurately detect the presence of complete MPFC injury.

Arthroscopic Patellofemoral Measurements Can Reliably Assess Patellar Instability

PURPOSE

To arthroscopically describe patellar position based on lateralization, tilt, and engagement, and compare measurements in normal, medial patellofemoral complex-(MPFC) deficient, and MPFC-reconstructed knees.

METHODS

In 10 cadaveric knees, arthroscopic patellar position was assessed by performing digital measurements on arthroscopic images obtained through a standard anterolateral portal. Lateralization was measured as millimeters overhang of the patella past the lateral edge of the lateral femoral condyle, viewing from the lateral gutter. Patellar tilt was calculated as the difference in medial and lateral distances from the patella to the trochlea, viewing from the sunrise view. Patellotrochlear distance was measured as the anteroposterior distance between the central trochlear groove and patella on the sunrise view. Measurements were obtained at 10° intervals of knee flexion from 0° to 90°, in intact knees (group 1), after arthroscopically transecting the MPFC fibers (group 2), and after MPFC reconstruction (group 3). Optimal cutoff values were identified to distinguish between intact versus MPFC-deficient states.

RESULTS

When compared to group 1, group 2 demonstrated increased patellar lateralization by 22.5% at 0°-40° knee flexion (P = .006), which corrected to baseline in group 3 (P = .006). Patellar tilt measurements demonstrated no differences between groups. Patellotrochlear distance increased by 21.0% after MPFC transection (P = .031) at 0°-40° knee flexion, with correction to baseline after MPFC reconstruction (P = .031). More than 7 mm of lateral overhang at 20°-30° flexion and >6 mm of patellotrochlear distance at 10°-20° flexion were found to indicate MPFC deficiency.

CONCLUSIONS

Utilizing standardized arthroscopic views, we identified significant increases in patellar lateralization and patellotrochlear distance in early knee flexion angles after MPFC transection, and these changes normalized after MPFC reconstruction.

CLINICAL RELEVANCE

Arthroscopic assessments of patellar position may be useful in evaluating patellofemoral stability during patellar stabilization surgery.

Are Patellofemoral Ligaments and Retinacula Distinct Structures of the Knee Joint? An Anatomic, Histological and Magnetic Resonance Imaging Study

There is disagreement regarding the description of the patellofemoral ligaments (PFLs), considered by some authors as capsular thickening and by others as independent ligaments. It was hypothesised that the PFLs and retinacula are structures with different histological features. The aim of this study was to describe the stabilising structures of the patella in detail and to determine if the PFLs and retinacula are different and separable structures from a macroscopic, microscopic and imaging viewpoint. An anatomical study was performed on eight knees from five cadavers (mean age, 56.2 years; range, 35–63 years), and a histological study was conducted on specimens from nine patients having a mean age of 65 years (range 35–84 years) who had undergone surgical knee procedures. The imaging study was based on 100 MRIs (96 patients). The mean age was 46 years (range 16–88), and the study analysed the capsular-ligamentous structures. In the medial compartment, the layers and structures were as follows: superficial layer, medial retinaculum; intermediate layer, Medial Collateral Ligament (MCL), Posterior Oblique Ligament (POL) and Medial Patellofemoral Ligament (MPFL); deep layer, deep part of the MCL and joint capsule. In the lateral compartment, the layers and structures were the following: superficial layer, lateral retinaculum; intermediate layer, Lateral Collateral Ligament (LCL) and Lateral Patellofemoral Ligament (LPFL); deep layer, joint capsule. All of the knees examined presented a clearly distinguishable MPFL and LPFL separable from the capsular layer. Histological study: there was a higher density of nerve fibres in retinacula compared to ligaments (p = 0.0034) and a higher content of elastic fibres in retinacula (p < 0.0005). In imaging, there was no difference between medial and lateral retinaculum thickness (p > 0.05). In conclusion, both the lateral and medial compartment can be described using the three-layer scheme. PFLs and retinacula are separate structures both macroscopically and according to imaging analysis. The retinacula respond to their specific function with a higher nerve fibre content and higher number of elastic fibres compared to the ligaments.

Medial patellofemoral ligament reconstruction: A review

INTRODUCTION

Reconstruction of the medial patellofemoral ligament (MPFL) is an effective surgical method for the treatment of lateral patellar instability. At present, there is not much controversies regarding the femoral attachment, however, the controversies regarding patellar attachment versus attachment, number of graft strands, tension, isometry and so on. The following electronic databases will be searched: PubMed, the Cochrane Library, Embase, Web of Science, Medline. We will consider articles published between database initiation and March 2021. MPFL in the subject heading will be included in the study. Language is limited to English. Research selection, data extraction, and research quality assessment were independently completed by 2 researchers.

CONCLUSIONS

MPFL reconstruction is a reliable technique for the treatment of patellofemoral instability. The Schöttle point is still the mainstream method for locating the femoral attachment, the patellar attachment for single-bundle is located at the junction of the proximal one third and the distal two third of the longitudinal axis of the patella. For double-bundles, one is located in the proximal one third of the medial patellar edge and another is in the center of the patellar edge. Meanwhile, the adjustment of graft tension during operation is very important.

Rehabilitation and Return to Sport After Medial Patellofemoral Complex Reconstruction

The medial patellofemoral complex (MPFC) consists of the medial patellofemoral ligament and medial quadriceps tendon femoral ligament, which play a critical role stabilizing the patella against lateral translation. After a patellar dislocation, athletes with recurrent dislocations have functional limitations that may limit their return to their prior level of competition, requiring surgical reconstruction. Although ample literature exists delineating return-to-play (RTP) considerations after anterior cruciate ligament reconstruction, there is a paucity of evidence specific to MPFC reconstruction. Athletes aiming to return to sport after MPFC reconstruction require the same methodical treatment approach to ensure safe RTP. A criterion-based periodical assessment of progress that measures range of motion, strength, neuromuscular control, balance, agility, and power are pivotal components of rehabilitating this population. A combination of objective and subjective criteria should be assessed when determining an individual’s readiness for sports-specific activities. A battery of functional tests, including quadriceps strength testing, single-limb hop testing, lateral step-down test, the lateral leap and catch test, the Y-balance test, and the depth jump should be considered when evaluating the athlete for readiness for sport, incorporating specific understanding of the biomechanics of the patellofemoral joint. We discuss the considerations for return-to-sport rehabilitation and testing after MPFC reconstruction, to provide clinicians working with an athletic population a framework to adequately prepare their athletes for safe return to sport.

Medial patellofemoral ligament is a part of the vastus medialis obliquus and vastus intermedius aponeuroses attaching to the medial epicondyle

PURPOSE

This study aimed to investigate the bony surface characteristic of the femoral attachment of the medial patellofemoral ligament (MPFL) and the correlation between the relevant layered structures, including muscular aponeurosis and the joint capsule, which contribute to patellofemoral joint (PFJ) stability.

METHODS

The morphology of the medial aspect of the medial condyle using micro-computed tomography and analysed cortical bone thickening in 24 knees was observed. For the macroscopic and histological analyses, 21 and 3 knees were allocated, respectively. The Kruskal-Wallis one-way analysis of variance test with Dunn post hoc testing was performed for statistical analysis.

RESULTS

At the level of the adductor tubercle, there were no significant differences in cortical bone thickness. At the level of the medial epicondyle (MEC), cortical bone thickness was considerably greater than that in other areas of the medial condyle (mean ± standard deviation, 0.60 ± 0.20 mm; p < 0.0001). Macroscopic analysis revealed that the deep aponeurosis of the vastus medialis obliquus and the tendinous arch of the vastus intermedius distally formed the composite membrane and adjoined to the joint capsule to firmly attach to MEC, which was located at 41.3 ± 5.7 mm posterior and 14.2 ± 3.1 mm superior to the joint cartilage. Histological analysis showed a composite membrane and adjoining capsule attached to MEC via fibrocartilage.

CONCLUSION

MPFL could be interpreted as part of the deep aponeurosis of the vastus medialis obliquus (VMO) and the tendinous arch of the vastus intermedius, which combined with the joint capsule to attach to MEC. The cortical bone thickening indicated that the tensile stresses were loaded on MEC in aged cadavers. Involvement of VMO and vastus intermedius aponeuroses in restored graft of MPFL could utilise the dynamic stability of surrounding muscles to mimic a native structure.

Quadriceps Tendon Attachment Technique for Medial Quadriceps Tendon-Femoral Ligament (MQTFL) Reconstruction in the Surgical Treatment of Recurrent Patella Dislocation

Medial quadriceps tendon-femoral ligament (MQTFL) reconstruction for prevention of recurrent patella dislocation is an alternative to medial patellofemoral ligament (MPFL) reconstruction. Because the reconstruction graft attaches to the quadriceps tendon, no patella drill hole is required, thereby eliminating iatrogenic fracture risk. The procedure remains anatomically accurate and early results are comparable to MPFL reconstruction for preventing patella dislocation. The MQTFL reconstruction graft is brought up under the vastus medialis obliquus distal to the patella apex, such that its orientation is directed toward the medial patellofemoral complex (MPFC) midpoint, also known as Tanaka's point. The graft is then secured by looping it around the vastus medialis and rectus femoris tendons, after which optimal graft length is easily established by cycling the knee, after which it is sutured securely into the deep quadriceps tendon precisely at the anatomic midpoint of the MPFC. Anatomic reconstruction of the MQTFL-in which graft orientation is crucial-confers reliable patellofemoral joint stability in the surgical treatment of patients with recurrent patella dislocations.

Anatomical Double-Bundle Medial Patellofemoral Ligament Reconstruction With Autologous Semitendinosus, a Single Patellar Tunnel Technique

Patellofemoral instability is one of the knee problems that can be found in up to 3% of knee injuries, especially in younger aged females. Recent biomechanical studies showed that the main soft tissue stabilizer for patellofemoral stability is the medial patellofemoral ligament (MPFL). More than 200 articles on MPFL reconstruction have been published. Some surgical techniques create multiple holes in the patellar area that may increase the risk of patellar fractures. This technique that we present here attempts to reduce the chance of patella-related complications, while maintaining stability of the reconstructed construct, reducing the use of a lengthy tendon graft within the patella and covering the footprint at the border of the patella closed to the native anatomy of the MPFL.

Current Concepts Regarding Patellofemoral Trochlear Dysplasia

Optimal treatment of patients with patellofemoral trochlear dysplasia and recurrent patellar instability requires in-depth understanding of this complex structural anomaly. An extensive review of the literature suggests that dysplasia occurs as a result of aberrant forces applied to the patellofemoral joint in the majority of cases. Evidence supports surgical stabilization that reconstructs the medial patellofemoral and/or medial quadriceps tendon-femoral ligament without added trochleoplasty in the majority of patients with trochlear dysplasia and recurrent patellar instability. Adding tibial tubercle transfer distally, medially, or anteromedially in those who need it to treat specific deficits in alignment or articular cartilage can be beneficial in selected patients with trochlear dysplasia and recurrent patellar instability. Trochleoplasty may be appropriate in those few cases in which permanent stable patellofemoral tracking cannot be restored otherwise, but the indications are not yet clear, particularly as trochleoplasty adds risk to the articular cartilage. Improved understanding of imaging techniques and 3-dimensional reproductions of dysplastic patellofemoral joints are useful in surgical planning for patients with recurrent patellar instability and trochlear dysplasia.

Femoral Origin Anatomy of the Medial Patellofemoral Complex: Implications for Reconstruction

PURPOSE

To report the shape and orientation of the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the proximal (medial quadriceps tendon femoral ligament, MQTFL) and distal (medial patellofemoral ligament, MPFL) fibers.

METHODS

In 20 cadaveric knees, the MPFC footprint on the medial femur was exposed. Images of the medial femur were analyzed using ImageJ software. The length and width of the MPFC footprint were described to the nearest 0.1 mm; the angle of its long axis was described relative to the axis of the femoral shaft (0.1°). The footprint's most proximal and distal margins were described in relation to the adductor tubercle and medial epicondyle. The differences between each were compared using paired t tests.

RESULTS

17 knees from 10 cadavers were included in this study. The MPFC footprint had a length of 11.7 ± 1.8 mm and a width of 1.7 ± 0.4 mm. The long axis of the footprint was at an angle 14.6° ± 16.6° anterior to the axis of the femoral shaft. The most proximal (MQTFL) fibers originated 7.4 ± 3.8 mm anterior and 1.8 ± 4.7 mm distal to the adductor tubercle and 4.1 ± 2.9 mm posterior and 8.4 ± 5.6 mm proximal to the medial epicondyle. The most distal (MPFL) fibers originated 4.9 ± 4.2 mm anterior and 12.7 ± 4.3 mm distal to the adductor tubercle, as well as 7.1 ± 2.4 mm posterior and 0.5 ± 5.6 mm distal to the medial epicondyle. The distal margin of the femoral MPFC footprint was 10.9 ± 1.7 mm distal (p < .001) and 2.6 ± 3.2 mm more posterior (p = .005) than the proximal margin.

CONCLUSIONS

The femoral footprint of the MPFC has a length almost 7 times greater than its width, with the distal margin being 10.9 mm distal and 2.6 mm posterior to the proximal margin.

CLINICAL RELEVANCE

This differential anatomy within the femoral origin suggests that MPFL and MQTFL reconstruction may require separate positions of femoral fixation to recreate the anatomy of these fibers.

Comparison of Patellofemoral Kinematics and Stability After Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament Reconstruction

BACKGROUND

There is a lack of evidence regarding the optimum extensor-sided fixation method for medial patellofemoral ligament (MPFL) reconstruction. There is increased interest in avoiding patellar drilling via soft tissue-only fixation to the distal quadriceps, thus reconstructing the medial quadriceps tendon-femoral ligament (MQTFL). The biomechanical implications of differing extensor-sided fixation constructs remain unknown.

HYPOTHESIS

The null hypothesis was there would be no differences between traditional MPFL reconstruction and MQTFL reconstruction with respect to resistance to lateral translation, patellar position, or patellofemoral contact pressures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine adult knee specimens were mounted on a jig that applied static, physiologic loads to the quadriceps tendons. Patellar position and orientation, knee flexion angle, and patellofemoral pressure were recorded at 8 different flexion angles between 0° and 110°. Additionally, a lateral patellar excursion test was conducted wherein a load was applied directly to the patella in the lateral direction with the knee at 30° of flexion and subjected to 2-N quadriceps loads. Testing was conducted under 4 conditions: intact, transected MPFL, MQTFL reconstruction, and MPFL reconstruction. For MQTFL reconstruction, the surgical technique established by Fulkerson was employed. For MPFL reconstruction, a traditional technique was utilized.

RESULTS

The patellar excursion test showed no significant difference between the MQTFL and intact states with respect to lateral translation. MPFL reconstruction led to significantly less lateral translation (P < .05) than all other states. There were no significant differences between MPFL and MQTFL reconstructions with respect to peak patellofemoral contact pressure. MPFL and MQTFL reconstructions both resulted in increased internal rotation of the patella with the knee in full extension.

CONCLUSION

Soft tissue-only extensor-sided fixation to the distal quadriceps (MQTFL) during patella stabilization appears to re-create native stability in this time 0 cadaver model. Fixation to the patella (MPFL) was associated with increased resistance to lateral translation.

CLINICAL RELEVANCE

Evolving anatomic knowledge and concern for patellar fracture has led to increased interest in MQTFL reconstruction. Both MQTFL and MPFL reconstructions restored patellofemoral stability to lateral translation without increasing contact pressures under appropriate graft tensioning, with MQTFL more closely restoring native resistance to lateral translation at the time of surgery.

Validity of intraoperative observation of graft length change pattern for medial patellofemoral ligament reconstruction

Background

The clinical outcome of the medial patellofemoral ligament reconstruction (MPFLR) based on graft length change pattern (length pattern group) was compared with MPFLR based on visual examination combined with palpation (visual/palpation group).

Methods

Physical findings, patient-reported outcome, and radiographic demonstration were evaluated pre- and postoperatively.

Results

The length pattern group had significantly lower risk of a positive apprehension test (Odds ratio 0.12, p < 0.01), and higher scores in postoperative Lysholm score (p = 0.046) and patient satisfaction (p = 0.036) than The visual/palpation group.

Conclusion

MPFLR based on graft length change pattern improved on patient-reported outcomes and apprehension test.

Level of evidence

Level Ⅲ, Retrospective comparative study.

Properties and Function of the Medial Patellofemoral Ligament: A Systematic Review

BACKGROUND

As the main passive structure preventing patellar lateral subluxation, accurate knowledge of the anatomy, material properties, and functional behavior of the medial patellofemoral ligament (MPFL) is critical for improving its reconstruction.

PURPOSE

To provide a state-of-the-art understanding of the properties and function of the MPFL by undertaking a systematic review and statistical analysis of the literature.

STUDY DESIGN

Systematic review.

METHODS

On June 26, 2018, data for this systematic review were obtained by searching PubMed and Scopus. Articles containing numerical information regarding the anatomy, mechanical properties, and/or functional behavior of the MPFL that met the inclusion criteria were reviewed, recorded, and statistically evaluated.

RESULTS

A total of 55 articles met the inclusion criteria for this review. The MPFL presented as a fanlike structure spanning from the medial femoral epicondyle to the medial border of the patella. The reported data indicated ultimate failure loads from 72 N to 208 N, ultimate failure elongation from 8.4 mm to 26 mm, and stiffness values from 8.0 N/mm to 42.5 N/mm. In both cadaveric and in vivo studies, the average elongation pattern demonstrated close to isometric behavior of the ligament in the first 50° to 60° of knee flexion, followed by progressive shortening into deep flexion. Kinematic data suggested clear lateralization of the patella in the MPFL-deficient knee during early knee flexion under simulated muscle forces.

CONCLUSION

A lack of knowledge regarding the morphology and attachment sites of the MPFL remains. The reported mechanical properties also lack consistency, thus requiring further investigations. However, the results regarding patellar tracking confirm that the lack of an MPFL leads to lateralization of the patella, followed by delayed engagement of the trochlear groove, plausibly leading to an increased risk of patellar dislocations. The observed isometric behavior up to 60° of knee flexion plausibly suggests that reconstruction of the ligament can occur at flexion angles below 60°, including the 30° and 60° range as recommended in previous studies.

Management of the First Patellar Dislocation: A Narrative Review

First patellar dislocation is a common injury of the knee, involving often adolescents and the active population. The consequences of the first episode can be various and potentially disabling. Among these, acute patellar dislocation can often result in recurrent patellar instability. Recurrent patellar instability is certainly multifactorial but depends primarily on the injury of the medial patellofemoral ligament (MPFL), the major soft-tissue stabilizer of the patella. Some classifications are extremely useful in establishing the diagnosis and therapy in patellofemoral disease, in particular in terms of instability. Among those, Henri Dejour and WARPS (weak atraumatic risky anatomy pain and subluxation)/STAID (strong traumatic anatomy normal instability and dislocation) classifications are certainly the most frequently used. There is no clear agreement on the management of the first patellar dislocation. A conservative approach seems to be the first choice in most of cases, but the presence of patellar displacement or osteochondral fractures makes surgery mandatory at the beginning. In addition, there is no clear consensus on which surgical strategy should be used to approach first dislocation, in relation to the possible variation in location of the MPFL injury, and to the eventual presence of preexisting predisposing factors for patellar instability. MPFL reconstruction may theoretically be more reliable than repair, while there is no clear evidence available that osseous abnormality should be addressed after the first episode of patellar dislocation. A narrative review was conducted to report the etiology, the diagnosis and all the possible treatment options of the first patellar dislocation. Modern classifications of the patellofemoral instability were also presented.

The Vastus Medialis Insertion Is More Proximal and Medial in Patients With Patellar Instability: A Magnetic Resonance Imaging Case-Control Study

Background:

The anatomy and function of the quadriceps muscle play a role in patellofemoral stability. Few studies have evaluated anatomic differences in the vastus medialis between patients with and without patellar instability.

Purpose:

To compare the anatomy of the vastus medialis using magnetic resonance imaging in patients with patellar instability to a control group.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A group of patients with patellar instability were sex-matched with a control group with anterior cruciate ligament tears, meniscal injuries, or sprains; patients younger than 15 years were excluded. The anatomy of the vastus medialis was examined by the distance between the distal origin of the vastus medialis in the femur and the medial femoral condyle, the distance from the proximal pole of the patella to the most distal insertion of the muscle and its ratio to the length of the articular surface of the patella, and a qualitative description of the insertion position of the muscle fibers (directly in the patella or the medial retinaculum).

Results:

Both groups comprised 78 knees (48 female; 61.5%). The mean age in the control and patellar instability groups was 30.2 ± 7.8 years and 25.6 ± 7.5 years, respectively (P = .001). The distance from the vastus origin to the condyle was 27.52 ± 3.49 mm and 26.59 ± 3.43 mm, respectively (P = .041); the distance from the proximal pole of the patella to the most distal muscle insertion was 17.59 ± 5.54 mm and 15.02 ± 4.18 mm, respectively (P < .001); and the ratio of this distance to the joint surface was 0.586 ± 0.180 and 0.481 ± 0.130, respectively (P < .001). In 75.6% of knees in the patellar instability group, the insertion of the vastus was into the medial retinaculum and not into the patella compared with 52.6% in the control group (P = .003; odds ratio, 2.8).

Conclusion:

The distal insertion of the vastus medialis differed in knees with patellar instability, with a more proximal insertion and less patellar coverage relative to controls, and was more frequently found in the retinaculum instead of directly in the patella.

The Ribbon-shaped Femoral Footprint of the Medial Patellofemoral Ligament: Implications for Reconstruction

The medial patellofemoral ligament (MPFL) is the primary static stabilizer to lateral translation of the patella and serves as part of the medial patellar soft tissue restraints. Because of the sensitivity of MPFL graft function after reconstruction to the position of the femoral tunnel, many studies have aimed to identify the exact point of the femoral origin, as well as defining techniques to confirm this position intraoperatively. We describe the ribbon-shaped footprint of the MPFL on the medial femur and the associated difficulty in identifying the origin as a single "point." Varying isometry and biomechanical functions have been shown to exist within the most proximal and most distal fibers, suggesting the function of the MPFL may not be fully recreated with a tubular graft in a round tunnel. We review the anatomical descriptions of the elongated femoral footprint of the MPFL and describe our surgical technique to recreate this.

An Updated Overview of the Anatomy and Function of the Proximal Medial Patellar Restraints (Medial Patellofemoral Ligament and the Medial Quadriceps Tendon Femoral Ligament)

The medial patellofemoral ligament (MPFL) has been widely accepted to function as "the primary static restraint to lateral patellar displacement." However, current growing evidence suggests that there is a complex of medial patellofemoral/tibial ligaments, both proximal [MPFL, and medial quadriceps tendon femoral ligament (MQTFL)], and distal (medial patellotibial ligament and the medial patellomeniscal ligament) which restrain lateral patellar translation at different degrees of knee flexion. Specifically, the MQTFL has gained popularity over the last decade because of pure soft tissue attachments into the extensor mechanism that allow for avoidance of drilling tunnels into the patella during reconstruction. The purpose of this article was to report on the current knowledge (anatomy, biomechanics, diagnosis, indications for surgery, and techniques) on the proximal medial patellar restraints, namely the MPFL and the MQTFL, collectively referred to as the proximal medial patellar restraints.

Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction

PURPOSE

The scientific literature concerning the anatomy of medial soft-tissue stabilizers of the patella is growing exponentially. Much of the surgical literature has focused on the role of the medial patellofemoral ligament (MPFL) and techniques to reconstruct it, yet our understanding of its anatomy has evolved during the past several years. Given this, we report on the current understanding of medial patellofemoral anatomy and implications for reconstruction.

METHODS

Current and historical studies of medial patellar anatomy were reviewed, which include the MPFL and medial quadriceps tendon femoral ligament (MQTFL), as well as that of the distal medial patellar restraints, the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML). In addition to the reported findings, the authors' anatomic descriptions of each ligament during their dissections were identified and recorded.

RESULTS

Despite the name of the MPFL, which implies that the ligament courses between the femur and patella, recent studies have highlighted the proximal MPFL fibers that attach to the quadriceps tendon, known as the MQTFL. The MPFL and MQTFL have also been referred to as the medial patellofemoral complex, reflecting the variability in anatomical attachment sites. The MPFL accounts for only half of the total restraint to lateral patellar displacement, and the remaining contributions to patellar stability are derived from the combination of the MPTL and MPML, which function primarily in greater degrees of knee flexion.

CONCLUSION

The understanding of the complexity of the medial patellar stabilizers continues to evolve. Although MPFL reconstruction is gaining wide acceptance as a procedure to treat patellar instability, it is important to recognize the complex and changing understanding of the anatomy of the medial soft-tissue stabilizers and the implications for reconstruction.

LEVEL OF EVIDENCE

V.

Biomechanical analysis of medial patellofemoral ligament reconstruction: FiberTape® with knotless anchors versus a semitendinosus tendon autograft with soft anchors

BACKGROUND

With the use of synthetic materials for medial patellofemoral ligament (MPFL) reconstruction, graft harvest is not necessary and this may facilitate post-operative rehabilitation. The purpose of this study was to compare the structural properties of MPFL reconstruction using a modern synthetic material (FiberTape® (FT), Arthrex) with knotless anchors or a semitendinosus (ST) tendon autograft with soft anchors.

METHODS

Nine human fresh-frozen amputated knees were used in this study. After the tensile strength of the native MPFL was measured, the MPFLs were reconstructed using two different surgical procedures, FT with knotless anchors (group A) and a ST with soft anchors (group B). Mechanical testing to failure of the reconstructed MPFLs was performed, and the ultimate load (N), stiffness (N/mm), and failure mode were recorded.

RESULTS

The mean (±standard deviation) ultimate load of the native MPFL was 130.6 ± 28.7 N, and all native MPFLs failed at the femoral insertion site. Ultimate load of group A was significantly higher than that of the native MPFL (175.9 ± 34.1 N, p < 0.05). In contrast, the ultimate load of group B was significantly lower than that of the native MPFL (102.7 ± 21.4 N, p < 0.05). The mean stiffness was significantly higher for MPFLs in group A (17.4 ± 4.3 N/mm) than in group B (8.5 ± 1.8 N/mm, p < 0.05). In group A, 5 specimens failed via a knotless anchor pullout at the femoral side, 3 via pullout of knotless anchors at the patella side and 1 via fracture (cheese cut) of the femur without breakage of knotless anchor. In group B, all specimens failed via soft anchor pullout at the patella side. There was no incidence of rupture of FT or ST.

CONCLUSION

FT with knotless anchors was stronger than a ST with soft tissue anchors for MPFL reconstruction.

Combined Soft Tissue Reconstruction of the Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament

Patellar dislocation is a major orthopaedic concern in pediatric and adult populations, with both conservative and surgical options available. Several surgical techniques of the combined or isolated reconstruction of the medial patellofemoral ligament are described in the literature using different grafts, locations, and types of fixations, providing different advantages and disadvantages. New recent developments in cadaveric dissection studies have unveiled the importance of structures that were neglected until recently, such as the medial quadriceps tendon-femoral ligament, which provides a connection between the medial femur and the quadriceps tendon component of the knee extensor mechanism. Hence, we present a surgical technique with combined reconstruction of the medial patellofemoral ligament and medial quadriceps tendon-femoral ligament without the use of hardware and with no need for patellar or femoral drilling (no physis compromise or risk of patellar fracture), which can be used concomitantly with other bony procedures.

Editorial Commentary: Medial Patellofemoral Complex: Driving a Better Understanding of Medial Knee Anatomy

Although its importance as the prime restraint to lateral patellar instability is undoubted, the anatomy of the medial patellofemoral ligament has never been agreed on. Since it was first described by Warren and Marshall in 1979, most of the anatomic studies confirmed its presence in 90% of the cases, but they usually provide inconsistent descriptions of its femoral and patellar attachments. It is proven that length changes in the reconstructed medial patellofemoral ligament depend principally on the femoral attachment site. Moreover, the femoral attachment site affects the patellar tilt, translation, and joint reaction force. Because of the early inconsistent descriptions of the medial patellofemoral ligament attachment sites, some authors have suggested that its anatomy is not fixed or may be patient specific.

Radiographic Landmarks for the Anterior Attachment of the Medial Patellofemoral Complex

PURPOSE

Because fluoroscopy is often used in graft placement during patellar stabilization surgery, the purpose of this study was to describe the radiographic landmarks for the anterior attachment midpoint of the medial patellofemoral complex (MPFC).

METHODS

Seventeen fresh-frozen cadaveric knees were dissected, and the MPFC was exposed from the articular side after a lateral parapatellar approach. The midpoint of the anterior attachment of the MPFC was identified using a ruler and marked with a pin. Lateral fluoroscopic images of the patella were then obtained and analyzed using digital analysis software. The distance from the superior articular pole to the pin was divided by the length of the articular surface to describe the location of the pin as a percentage of patellar articular length.

RESULTS

Of the 17 cadaveric knees, 2 were excluded because of lack of MPFC fibers. In the remaining 15 knees, the mean (±standard deviation) proximal-distal width of the attachment to the patella and/or vastus intermedius tendon was 41 ± 10 mm, spanning from 15 ± 6 mm proximal to the superior pole of the patella to 27 ± 8 mm distal to it. When viewed on lateral fluoroscopic images, the MPFC midpoint was 19% ± 14% of the patellar articular length from the superior articular pole.

CONCLUSIONS

In this study, the radiographic landmarks that correlate to the anatomic midpoint of the anterior MPFC attachment are 19% ± 14% of the articular surface from the superior pole of the patella.

CLINICAL RELEVANCE

Recent reports on medial patellofemoral ligament anatomy now include fibers that extend to the quadriceps tendon, summarized as the MPFC. With the inclusion of these fibers, the midpoint of the anterior MPFC attachment is more proximal than that of the medial patellofemoral ligament alone. Because fluoroscopy is often used intraoperatively to guide graft placement, this study correlates radiographic landmarks with anatomic findings of the MPFC midpoint on its attachment to the extensor mechanism.

Combined Reconstruction of the Medial Patellofemoral Ligament (MPFL) and Medial Quadriceps Tendon-Femoral Ligament (MQTFL) for Patellar Instability in Children and Adolescents: Surgical Technique and Outcomes

OBJECTIVES

A variety of surgical options exist to treat the challenging problem of recurrent patellar instability in children and adolescents. The goal of the current study is to describe a novel combined reconstruction technique of both the medial patellofemoral ligament (MPFL) and the medial quadriceps tendon-femoral ligament (MQTFL) and report patient outcomes of a single-surgeon series.

METHODS

All patients studied underwent simultaneous MPFL and MQTFL reconstruction for patellar instability using gracilis allograft. Demographic, clinical, and radiographic data were collected. Subjective outcomes were assessed for a minimum of 1 year postoperatively.

RESULTS

Twenty-five patients (27 knees), including 15 female and 10 male individuals with an average age of 15.0±2.2 years (range, 10.3 to 18.9), were included. Prior ipsilateral patellofemoral surgery had been performed in 6 of 25 (24%) patients. Simultaneous hemiepiphysiodesis for valgus deformity at the time of combined reconstruction was performed in 5 of 25 (20%) patients. Preoperative imaging showed a mean tibial tubercle-trochlear groove of 17.2±3.8, Caton-Deschamps Index (CDI) of 1.13±0.16, and trochlear dysplasia Dejour A/B [22/26 (85%)] or Dejour C/D [4/26 (15%)]. A total of 18 patients (19 knees, 72%) returned outcomes questionnaires at a mean 2.0±0.5 years after surgery. Mean Kujala, Pedi-IKDC, and Lysholm scores were 85.9±13.9, 81.5±15.2, and 84.3±13.5, respectively. Later revision procedure (tibial tubercle osteotomy) for recurrent patellar instability was required in 2 of 25 patients (8%) patients, and another patient reported persistent instability not requiring revision. Return to sports was possible in 10 of 13 self-reported athletes (77%) at a mean of 5.8±3.9 months (range, 2 to 15).

CONCLUSIONS

The present study describes a combined MPFL-MQTFL reconstruction technique with favorable short-term results. Although particularly useful in the skeletally immature patient where tibial tubercle osteotomy should be avoided and patellar fixation minimized, combined reconstruction may potentially be appropriate for older patients with patellofemoral instability as well. This technique more closely recreates the native anatomy of both the MPFL and MQTFL, may decrease the risk of patellar fracture, and can be useful in the revision setting.

LEVEL OF EVIDENCE

Level IV.

Medial Quadriceps Tendon Femoral Ligament Reconstruction Technique and Surgical Anatomy

Medial patellofemoral ligament reconstruction risks patellar fracture with the osseous violation necessary for patellar attachment. Anatomic studies identify an entire medial patellofemoral complex of structures responsible for medial restraint to patellar lateral instability. One specific component of this complex is the medial quadriceps tendon femoral ligament (MQTFL). This note presents the technique, pearls and pitfalls, and critical surgical anatomy necessary for successful MQTFL reconstruction-a treatment strategy for patellar instability with no increased risk for patellar fracture. An autograft hamstring tendon or allograft tendon is fixed to the anatomically identified femoral origin and passed deep to the vastus medialis obliquus to then weave around the distal medial quadriceps tendon. This simulates the native anatomic interdigitation of the MQTFL with the quadriceps tendon and provides a stable restraint to prevent lateral patellar subluxation or dislocation.

A polygon-shaped complex appearance of medial patellofemoral ligament with dynamic functional insertion based on an outside-in and inside-out dissection technique

PURPOSE

To describe the unclarified characteristics of medial patellofemoral ligament and its relation to neighboring structures.

METHODS

Sixteen fresh-frozen human knees were dissected in using outside-in and inside-out combined technique. The patellar side attachment was observed from the inside view and femoral side from outside view.

RESULTS

The medial patellofemoral ligament was described a complex and multiconnected structure. The femoral side included the upper and lower portion, of which the upper portion attached on the femur with mean width 7.5 ± 1.1 mm and its superficial fibers extended to the adductor magnus tendon and the medial gastrocnemius tendon, and of which the lower portion appeared a right-triangle connected to the MCL without bony attachment. From inside view, the patellar attachment consisted of the bony and non-bony parts. The width of bony attachment was measured mean 16.3 ± 3.8 mm, and the non-bony attachment was found attached on the vastus intermedius tendon with mean width 21.7 ± 4.8 mm. The average thickness was 0.4 ± 0.1 mm and the length were inside assessed mean 67.9 ± 6.1 mm.

CONCLUSION

The medial patellofemoral ligament which dissected a complicated structure with bony and non-bony attachment and multi-connected to neighboring structures on both patella and femur side appears as a polygon-shaped complex structure.

The Anatomy of the Medial Patellofemoral Complex

The term "medial patellofemoral complex" (MPFC) was proposed to describe the static medial stabilizer of the patella, typically referred to as the medial patellofemoral ligament. In light of our increasing understanding of the attachment of its fibers to the quadriceps tendon in addition to the patella, the term MPFC is used in this article. The purpose of this article is to describe and discuss the anatomy of the MPFC.

Editorial Commentary: Medial Patellofemoral Ligament Reconstruction Alone Works Well When the Patient Has Normal Alignment, But Don't Forget to Move the Tibial Tubercle When Necessary!

Medial patellofemoral ligament reconstruction works very well, regardless of graft choice, for controlling lateral patella instability when performed correctly in patients with normal alignment, even in the face of trochlea dysplasia. However, sometimes a tibial tubercle transfer is necessary in patella instability surgery.

The interaction between the vastus medialis and vastus intermedius and its influence on the extensor apparatus of the knee joint

PURPOSE

Although the vastus medialis (VM) is closely associated with the vastus intermedius (VI), there is a lack of data regarding their functional relationship. The purpose of this study was to investigate the anatomical interaction between the VM and VI with regard to their origins, insertions, innervation and function within the extensor apparatus of the knee joint.

METHODS

Eighteen human cadaveric lower limbs were investigated using macro-dissection techniques. Six limbs were cut transversely in the middle third of the thigh. The mode of origin, insertion and nerve supply of the extensor apparatus of the knee joint were studied. The architecture of the VM and VI was examined in detail, as was their anatomical interaction and connective tissue linkage to the adjacent anatomical structures.

RESULTS

The VM originated medially from a broad hammock-like structure. The attachment site of the VM always spanned over a long distance between: (1) patella, (2) rectus femoris tendon and (3) aponeurosis of the VI, with the insertion into the VI being the largest. VM units were inserted twice-once on the anterior and once on the posterior side of the VI. The VI consists of a complex multi-layered structure. The layers of the medial VI aponeurosis fused with the aponeuroses of the tensor vastus intermedius and vastus lateralis. Together, they form the two-layered intermediate layer of the quadriceps tendon. The VM and medial parts of the VI were innervated by the same medial division of the femoral nerve.

CONCLUSION

The VM consists of multiple muscle units inserting into the entire VI. Together, they build a potential functional muscular complex. Therefore, the VM acts as an indirect extensor of the knee joint regulating and adjusting the length of the extensor apparatus throughout the entire range of motion. It is of clinical importance that, besides the VM, substantial parts of the VI directly contribute to the medial pull on the patella and help to maintain medial tracking of the patella during knee extension. The interaction between the VM and VI, with responsibility for the extension of the knee joint and influence on the patellofemoral function, leads readily to an understanding of common clinical problems found at the knee joint as it attempts to meet contradictory demands for both mobility and stability. Surgery or trauma in the anteromedial aspect of the quadriceps muscle group might alter a delicate interplay between the VM and VI. This would affect the extensor apparatus as a whole.

Quantitative and Qualitative Analysis of the Medial Patellar Ligaments: An Anatomic and Radiographic Study

BACKGROUND

The qualitative and quantitative anatomy of the medial patellar stabilizers has been reported; however, a quantitative analysis of the anatomic and radiographic attachments of all 4 ligaments relative to anatomic and osseous landmarks, as well as to one another, has yet to be performed.

PURPOSE

To perform a qualitative and quantitative anatomic and radiographic evaluation of the medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), medial patellomeniscal ligament (MPML), and medial quadriceps tendon femoral ligament (MQTFL) attachment sites, with attention to their relationship to pertinent osseous and soft tissue landmarks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired fresh-frozen human cadaveric knees were dissected, and the MPFL, MPTL, MPML, and MQTFL were identified. A coordinate measuring device quantified the attachment areas of each structure and its relationship to pertinent bony landmarks. Radiographic analysis was performed through ligament attachment sites and relevant anatomic structures to assess their locations relative to pertinent bony landmarks.

RESULTS

Four separate medial patellar ligaments were identified in all specimens. The center of the MPFL attachments was 14.3 mm proximal and 2.1 mm posterior to the medial epicondyle and 8.3 mm distal and 2.7 mm anterior to the adductor tubercle on the femur and 8.9 mm distal and 19.9 mm medial to the superior pole on the patella. The MQTFL had a mean insertion length of 29.3 mm on the medial aspect of the distal quadriceps tendon. The MPTL and MPML shared a common patellar insertion and were 9.1 mm proximal and 15.4 mm medial to the inferior pole. The MPTL attachment inserted on a newly identified bony ridge, which was located 5.0 mm distal to the joint line. The orientation angles of the MPTL and MPML with respect to the patellar tendon were 8.3° and 22.7°, respectively.

CONCLUSION

The most important findings of this study were the correlative anatomy of 4 distinct medial patellar ligaments (MPFL, MPTL, MPML, MQTFL), as well as the identification of a bony ridge on the medial proximal tibia that consistently served as the attachment site for the MPTL. The quantitative and radiographic measurements, while comparable with current literature, detailed the meniscal insertion of the MPML and defined a patellar insertion of the MPTL and the MPML as a single attachment. The data allow for reproducible landmarks to be established from previously known bony and soft tissue structures.

CLINICAL RELEVANCE

The findings of this study provide the anatomic foundation needed for an improved understanding of the role of medial-sided patellar restraints. This will help to further refine injury patterns and/or soft tissue deficiencies that result in lateral patellar instability, which can then be addressed with an anatomic-based reconstruction or repair technique and potentially lead to improved outcomes.

Anatomic Double-Bundle Medial Patellofemoral Ligament Reconstruction with Autologous Semitendinosus: Aperture Fixation Both at the Femur and the Patella

Medial patellofemoral ligament (MPFL) represents the main restraint against lateral patellar displacement. The MPFL insertion at the patella is up to 30 mm wide and is located along the upper half of the medial patellar rim. The femoral insertion of the MPFL is approximately 10 mm distal to the apex of the adductor tubercle and 16 mm proximal to the medial epicondyle. Since most of the patients suffer from MPFL rupture just after the first patellar dislocation, MPFL reconstruction results necessarily in all cases of chronic objective patellar instability to reestablish the primary passive patellofemoral stabilizer. Over time, different techniques of MPFL reconstruction have been proposed with promising results in terms of patient satisfaction and redislocation rate. However, each of these techniques may present peculiar problems and/or complications. An anatomic double-bundle MPFL reconstruction through an aperture fixation both at the femur and at the patella is here presented. The anatomic double-bundle MPFL reconstruction could allow recreating the fan-shape and biomechanics of original MPFL, whereas aperture fixation could provide a strong and safe fixation without risk of loosening or slackening of the graft.

Origin and insertion of the medial patellofemoral ligament: a systematic review of anatomy

PURPOSE

The medial patellofemoral ligament (MPFL) is the major medial soft-tissue stabiliser of the patella, originating from the medial femoral condyle and inserting onto the medial patella. The exact position reported in the literature varies. Understanding the true anatomical origin and insertion of the MPFL is critical to successful reconstruction. The purpose of this systematic review was to determine these locations.

METHODS

A systematic search of published (AMED, CINAHL, MEDLINE, EMBASE, PubMed and Cochrane Library) and unpublished literature databases was conducted from their inception to the 3 February 2016. All papers investigating the anatomy of the MPFL were eligible. Methodological quality was assessed using a modified CASP tool. A narrative analysis approach was adopted to synthesise the findings.

RESULTS

After screening and review of 2045 papers, a total of 67 studies investigating the relevant anatomy were included. From this, the origin appears to be from an area rather than (as previously reported) a single point on the medial femoral condyle. The weighted average length was 56 mm with an 'hourglass' shape, fanning out at both ligament ends.

CONCLUSION

The MPFL is an hourglass-shaped structure running from a triangular space between the adductor tubercle, medial femoral epicondyle and gastrocnemius tubercle and inserts onto the superomedial aspect of the patella. Awareness of anatomy is critical for assessment, anatomical repair and successful surgical patellar stabilisation.

LEVEL OF EVIDENCE

Systematic review of anatomical dissections and imaging studies, Level IV.

The anatomy and isometry of a quasi-anatomical reconstruction of the medial patellofemoral ligament

PURPOSE

To describe the anatomy of the medial patellofemoral ligament (MPFL) and its relationship to the Adductor Magnus (AM) tendon as well as the behaviour exhibited in length changes during knee flexion.

METHODS

Ten cadaveric knees were dissected. The length from the superior and inferior patellar origin of the MPFL to its femoral insertion was measured at different degrees of knee flexion (0°, 30°, 60°, 90° and 120°). The same measures were made from both patellar origins of the MPFL up to the femoral insertion of the AM. The distance between the insertion of the AM and the Hunter canal was also measured.

RESULTS

In general, isometry up to 90° was seen in all measures of the MPFL and those of the AM. The most isometric behaviour was seen in 2 measures: the length of the AM femoral insertion up to the inferior origin of the MPFL on the patella and the length of the femoral insertion of the MPFL up to the inferior origin of the MPFL on the patella. Similar behaviour was seen regardless of the anatomical or quasi-anatomical femoral point of attachment (n.s.). The distance from the AM tendon to the Hunter canal had a mean value of 78.6 mm (SD 9.4 mm).

CONCLUSION

The behaviour exhibited during the changes in the length of the anatomical femoral footprint of the MPFL and the AM is similar. Neurovascular structures were not seen at risk. This is relevant in the daily clinical practice since the AM tendon might be a suitable point of insertion for MPFL reconstruction.

Morphology of insertion sites on patellar side of medial patellofemoral ligament

PURPOSE

The purpose of this study was to clarify the insertion sites on the patellar side of the medial patellofemoral ligament (MPFL).

METHODS

A total of 35 nonpaired human cadaveric knees were used in this study. After identification of the MPFL, the insertion sites on the patellar side of the MPFL were marked. Three-dimensional images were created, and the location and morphology of these insertion sites were analysed.

RESULTS

The morphology of the insertion sites on the patellar side of the MPFL was consistent. The proximal fibres of the MPFL were inserted to the deep fascia of the vastus medialis obliquus (VMO) and medial margin of the vastus intermedius (VI). The distal fibres of the MPFL were inserted to the medial margin of the patella directly. The insertion lengths of the VMO, VI, and patella were 26.7 ± 5.0, 28.5 ± 4.4, and 18.5 ± 4.4 mm, respectively. The rate of the vertical distance from the superior pole of the patella to the superior edge of the MPFL in relation to the total patellar height was 12 ± 4.4 %. At the distal edge, the rate was 58 ± 9.6 %.

CONCLUSION

The insertion sites on the patellar side of the MPFL were consistent. The MPFL inserted into the VMO and VI was significantly longer than into the patella. The clinical relevance of this study is to improve understanding of the anatomy of the insertion sites on the patellar side of the MPFL and the pathophysiology of patellar dislocation.

Medial patellofemoral ligament reconstruction using a bone groove and a suture anchor at patellar: a safe and firm fixation technique and 3-year follow-up study

Background

Graft fixation is critical to the restoration of the medial patella of femoral ligament function and long-term success. Numerous fixations at the patella have been described, while the complications including patellar fractures, violation of the posterior patella and delay of tendon-to-bone healing remain significant challenges. Here, we describe a safe and firm fixation at the patellar for medial patellofemoral ligament (MPFL) reconstruction and explore the safety angle of drilling the suture anchor at different morphology of the patellar. Moreover, we evaluate the results at a 3-year follow-up.

Methods

Combined bone groove and suture anchor fixation at the patella was performed on 26 patients (16 females, 10 males; mean age 26.3 ± 4.7 years) diagnosed with recurrent patellar dislocation. The drilling direction of the suture anchor referred to the safety angle according to the Wiberg type classification. The safety angle was defined as the angle between the drill tunnel and a line that connected the medial and lateral margins of the patella and was established following computed tomography assessment of 117 patients who were diagnosed with patellar dislocation in our hospital according to the Wiberg type classification (I:29, II:65, III:23). X-ray, Lysholm, Kujala and Tegner scores were obtained preoperatively and at the time of final follow-up.

Results

There were no patellar complications, including fracture and redislocation. Average congruence, patella tilt angles and lateral patella angle were significantly changed (P < 0.01). The Lysholm, Kujala and Tegner scores were significantly increased (P < 0.01). The safe angles of male and female patients according to the patellar Wiberg type classification were less than 45.32 ± 1.76 and 41.20 ± 1.33, 69.74 ± 1.38 and 63.66 ± 1.45 and 84.11 ± 1.67 and 80.26 ± 1.73, respectively.

Conclusions

We achieved encouraging results with this fixation at the patellar. When drilling from Wiberg type I to type III patellar, the suture anchor should be more vertical. When fixing the patellar of female patients, the drilling suture anchor should be more sloping.

Variability in the Patellar Attachment of the Medial Patellofemoral Ligament

PURPOSE

To describe and quantify the variability of the attachments of the medial patellofemoral ligament (MPFL).

METHODS

Thirty-three cadaveric knees were dissected, and the MPFL was identified from the articular side after anterior reflection of the extensor mechanism and removal of the synovium. The width of the MPFL at its femoral origin and anterior attachment was measured using digital calipers once by 1 examiner. The percentage of fibers that attached to the patella versus the quadriceps tendon was calculated relative to the width of the total attachment. The length of the MPFL fibers was measured from the femoral origin to (1) the patella and (2) the quadriceps tendon and compared using paired t tests.

RESULTS

Four knees had no identifiable MPFL fibers, and 1 was excluded because of the presence of osteophytes. In 28 knees, the mean width of the MPFL was 10.7 ± 1.8 mm at the femoral origin and 30.4 ± 5.5 mm at the patellar attachment. One knee had all MPFL fibers attaching to the patella, and another had all fibers attaching to the quadriceps tendon. The remainder had attachments to both structures, with 57.3% ± 19.5% (range, 0% to 100%) of fibers attaching to the patella. Mean length of the MPFL fibers was 62.6 ± 5.2 mm from the femoral origin to the patella and 69.7 ± 5.5 mm from the femoral origin to the quadriceps tendon (7.1-mm difference; P < .0001).

CONCLUSIONS

MPFL fibers vary in their width and percentage of attachments to the patella and quadriceps tendon. Further studies are needed to identify the appropriate fixation points to re-create the anatomy and isometry of the MPFL during reconstruction for patellar stabilization.

CLINICAL RELEVANCE

Variability in the anatomy of the MPFL suggests that optimal anatomic graft placement may vary during reconstruction of this ligament.

The Anatomic Midpoint of the Attachment of the Medial Patellofemoral Complex

BACKGROUND

The medial patellofemoral ligament varies in attachment of its fibers to the patella and vastus intermedius tendon. Our aim was to identify and describe its anatomic midpoint. To account for the variability of the attachment site, we refer to it as the medial patellofemoral complex.

METHODS

Using AutoCAD software, we identified the midpoint of the medial patellofemoral complex attachment on photographs of 31 cadaveric knee dissections. The midpoint was referenced relative to the superior articular surface of the patella (P1) and was described in terms of the percentage of the patellar articular length distal to this point. A second point, at the junction of the medial border of the vastus intermedius tendon with the superior articular border of the patella, was identified (P2). The distances of the midpoint to P1 and P2 were calculated and were compared using paired t tests.

RESULTS

Twenty-five images had appropriate quality and landmarks for digital analysis. The midpoint of the medial patellofemoral complex was located a mean (and standard deviation) of 2.3% ± 15.8% of the patellar articular length distal to the superior pole and was at or proximal to P1 in 12 knees. In all knees, the midpoint was at or proximal to P2. After exclusion of 2 knees with vastus intermedius tendon attachments only, the medial patellofemoral complex midpoint was closer to P2 (5.3% ± 8.6% of the patellar articular length) than to P1 (9.3% ± 8.5% of the patellar articular length) (p = 0.06).

CONCLUSIONS

The midpoint of the medial patellofemoral complex was 2.3% of the articular length distal to the superior pole of the patella. Additionally, we describe an anatomic landmark at the junction of the medial border of the vastus intermedius tendon and the articular border of the patella that approximates the midpoint of this complex.

CLINICAL RELEVANCE

Our study shows that the anatomic midpoint of the attachment of the medial patellofemoral complex is proximal to the junction of the medial vastus intermedius tendon and the articular border of the patella, suggesting that graft placement may be more anatomic on the vastus intermedius tendon rather than on the patella.