Medial Patellofemoral Ligament Injury Research Articles

The Adductor Sling Technique for Pediatric Medial Patellofemoral Ligament Reconstruction Better Resists Dislocation Loads When Compared With Adductor Transfer at Time Zero in a Cadaveric Model

To characterize the ability of the intact medial patellofemoral ligament (MPFL) and the adductor transfer and adductor sling MPFL reconstruction techniques to resist subluxation and dislocation in a cadaveric model. Nine fresh-frozen cadaveric knees were placed on a custom testing fixture with the femur fixed parallel to the floor, the tibia placed in 20° of flexion, and the patella attached to a load cell. The patella was displaced laterally, and subluxation load (in newtons), dislocation load (in newtons), maximum failure load (in newtons), patellar displacement at failure, and mode of failure were recorded. Testing was conducted with the MPFL intact and after the adductor sling and adductor transfer reconstruction techniques. Statistical analysis was completed using 1-way repeated-measures analysis of variance with the Holm-Šidák post hoc test. The subluxation load was not significantly different between groups. The native MPFL dislocation load was significantly higher than the dislocation loads of both reconstruction techniques, but no significant difference between the dislocation loads of the 2 reconstruction techniques occurred. The native MPFL failure load was significantly higher than the failure loads of both reconstruction techniques. The adductor sling failure load was significantly higher than the adductor transfer failure load. The mode of failure varied across groups. The native MPFL failed by femoral avulsion, patellar avulsion, and midsubstance tear. The main mode of failure for adductor transfer was pullout, whereas failure for the adductor sling technique most often occurred at the sutures. Most of the native MPFLs and all adductor sling reconstructions failed after dislocation. The adductor transfer reconstructions were much more variable, with failures spanning from before subluxation through dislocation. Our cadaveric model showed that neither the adductor transfer technique nor the adductor sling technique restored failure load to that of the native condition. There was no significant difference in the subluxation or dislocation loads between the 2 MPFL reconstructions, but the adductor sling technique resulted in a higher load to failure. The adductor transfer technique frequently failed before subluxation or dislocation when compared with the adductor sling technique and the native MPFL. The best technique for MPFL reconstruction in patients with open physes is a topic of debate. Given the long-term consequences of MPFL injury and potential for growth plate disturbance, it is important to study MPFL reconstruction techniques thoroughly, including in the laboratory setting.

Acute patellar dislocation: how skeletal maturity affects patterns of injury.

The main objective of this study was to understand the role of skeletal maturity in the different patterns of osteochondral and ligamentous injuries after an acute lateral patellar dislocation. Two radiologists independently reviewed MRIs of 212 knees performed after an acute lateral patellar dislocation to evaluate the presence of high-grade patellar osteochondral injury, femoral osteochondral injury, and medial patellofemoral ligament injury. The association of skeletal maturity (indicated by a closed distal femoral physis), age, sex, and first-time versus recurrent dislocation with each of these various lesions was analyzed using Chi-square or T test, and multivariable logistic regression with estimation of odds ratios (OR). Skeletal maturity was significantly associated with high-grade patellar osteochondral injury [OR=2.72 (95% CI 1.00, 7.36); p=0.049] and femoral-side MPFL tear [OR=2.34 (95% CI 1.05, 5.25); p=0.039]. Skeletal immaturity was significantly associated with patellar-side MPFL tear [OR=0.35 (95% CI 0.14, 0.90); p=0.029]. Patterns of injury to the patella and medial patellofemoral ligament vary notably between the skeletally immature and mature, and these variations may be explained by the inherent weakness of the patellar secondary physis.

MRI Findings Associated With Anterior Cruciate Ligament Tears in National Football League Athletes.

Anterior cruciate ligament (ACL) tears are a high-frequency injury requiring a lengthy recovery in professional American football players. Concomitant pathology associated with ACL tears as identified on magnetic resonance imaging (MRI) is not well understood in these athletes. To describe the MRI findings of concomitant injuries associated with ACL tears among athletes in the National Football League (NFL). Cross-sectional study; Level of evidence, 3. Of 314 ACL injuries in NFL athletes from 2015 through 2019, 191 complete MRI scans from the time of primary ACL injury were identified and reviewed by 2 fellowship-trained musculoskeletal radiologists. Data were collected on ACL tear type and location, as well as presence and location of bone bruises, meniscal tears, articular cartilage pathology, and concomitant ligament pathology. Mechanism data from video review were linked with imaging data to assess association between injury mechanism (contact vs noncontact) and presence of concomitant pathology. Bone bruises were evident in 94.8% of ACL tears in this cohort, most often in the lateral tibial plateau (81%). Meniscal, additional ligamentous, and/or cartilage injury was present in 89% of these knees. Meniscal tears were present in 70% of knees, lateral (59%) more than medial (41%). Additional ligamentous injury was present in 71% of all MRI scans, more often a grade 1/2 sprain (67%) rather than a grade 3 tear (33%), and most often involving the medial collateral ligament (MCL) (57%) and least often the posterior cruciate ligament (10%). Chondral damage was evident in 49% of all MRI scans, with ≥1 full-thickness defect in 25% of all MRI scans, most often lateral. Most (79%) ACL tears did not involve direct contact to the injured lower extremity. Direct contact injuries (21%) were more likely to have a concomitant MCL tear and/or medial patellofemoral ligament injury and less likely to have a medial meniscal tear. ACL tears were rarely isolated injuries in this cohort of professional American football athletes. Bone bruises were almost always present, and additional meniscal, ligamentous, and chondral injuries were also common. MRI findings varied by injury mechanism.

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

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. 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). 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.

Habitual Patellar Dislocation Treated By Anteromedial Tibial Tubercle Transfer (Fulkerson Osteotomy) with Medial Patellofemoral Ligament Reconstruction Using Superficial Layer of Quadriceps Tendon Autograft: A Case Report

Introduction: Bony malalignment and soft tissue injury of Medial Patellofemoral Ligament (MPFL) in chronic patellar instability is considered as a surgical indication for distal realignment in the form of anteromedial tibial tubercle transfer (Fulkerson osteotomy) with MPFL reconstruction, are effectively unloads the lateral patella while making the patellofemoral joint more congruous, stable and pain free. Method: A 26 years old male with left habitual patellar dislocation and pain on his left knee. The patient underwent Fulkerson osteotomy (Tibial tuberosity elevation osteotomy and medial transfer) and medial patellofemoral ligament (MPFL) reconstruction using superficial layer of quadriceps tendon autograft. The patient underwent arthroscopic examination preoperatively and found cartilage lesion of patella (Outerbridge type III). Conclusion: Fulkerson osteotomy and MPFL reconstruction is a successful procedure to treat habitual patellar dislocation and patellofemoral pain. The Fulkerson osteotomy can improve the patella stability and knee function. MPFL reconstruction using superficial layer of quadriceps tendon was simple and has fewer complication than using other autografts, such as hamstring tendon, adductor tendon, and patellar tendon.

Medial Patellofemoral Ligament Reconstruction With a Single-Limb Allograft: A Reproducible and Effective Technique

Background: Medial patellofemoral ligament (MPFL) injury occurs in up 96% of lateral patellar dislocations, commonly affecting those less than 20 years old. The MPFL can be reconstructed using either a double-limb or single-limb technique. While both techniques achieve similar patient outcomes, a single-limb technique may require less operative time. Indications: The MPFL reconstruction is indicated in patients with recurrent patellar subluxations, dislocations, or unresolved apprehension. Care should be exercised in identifying whether patients require additional procedures in addition to MPFL reconstruction such as tibial tubercle osteotomy or trochleoplasty. These considerations include TT-TG >17 to 20 mm and Dejour B/D trochlear dysplasia. Technique Description: Following diagnostic arthroscopy, a medial peripatellar incision is made. Layers 1 and 2 are sharply dissected over the patellar periosteum, and tissue planes are subsequently developed using Metzenbaum scissors. A plane between layers 2 and 3 extending from the medial patella to the medial femoral epicondyle is developed. Using fluoroscopy, Schöttle point is identified, and a femoral tunnel is drilled. Two PEEK anchors are placed at the junction of the proximal one-third and distal two-thirds of the patella. In parallel, a tibialis anterior graft is sized, whipstitched, and tensioned on the back table. One end of the prepared graft is secured in the femoral tunnel with a PEEK tenodesis screw. The graft is then shuttled between layers 2 and 3, followed by fixation on the patellar side using the previously placed suture anchors. Isometry of the graft is confirmed under direct and arthroscopic visualization. Results: In multiple systematic reviews of single-limb versus double-limb MPFL reconstruction, no differences were observed in terms of patient-reported outcome scores, repeat dislocation, and reoperation. Furthermore, a recent meta-analysis suggests a trend toward less postoperative stiffness (1.2% vs 3.5%, P = .09) for single-bundle techniques. Discussion/Conclusion: Single-limb MPFL reconstruction is reproducible and effective, with clinically satisfactory outcomes and low failure rates. Single-limb MPFL reconstruction demonstrates similar outcomes as double-limb reconstruction, with a potential decrease in surgical time and postoperative stiffness. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Male sex is an independent risk factor for patellar osteochondral fractures following acute patellar dislocation in pediatric patients

PurposeAlthough most patellar dislocations are associated with medial patellofemoral ligament (MPFL) injury, many patients also sustain concomitant patellar osteochondral fractures following a patellar dislocation. Few prior studies have described or evaluated risk factors for patellar osteochondral fractures in pediatric patients. The purpose of the present study was to describe the incidenceand location of patellar osteochondral fractures following acute patellar dislocation in pediatric patients. In addition, we described risk factors for patellar osteochondral fractures in this population. We hypothesized that most fractures would occur at the inferomedial quadrant of the patella following a traumatic injury mechanism.MethodsFollowing Institutional Review Board approval, the electronic medical record was queried to identify pediatric patients ≤ 18 years old who underwent MPFL reconstruction (MPFLR) or non-operative treatment for patellar instability between July 2016 and February 2020. Osteochondral fractures were defined as full-thickness chondral injuries with attached subchondral bone or purely osseous injuries measuring ≥ 3 mm (mm) in at least two magnetic resonance imaging (MRI) planes. Patients were included in the study if they had complete preoperative x-ray and MRI studies with minimum 6-month follow-up. Patients were excluded if they had incomplete imaging, isolated chondral fractures, or less than 6 months follow-up. Univariate analysis was used to identify patient factors associated with osteochondral fractures. Multivariate regression analysis was used to identify risk factors for osteochondral fractures.ResultsSixty patients (63 knees) were included in the study, 15 (23.8%) of whom had a patellar osteochondral fracture. The majority of osteochondral fractures (87%) involved the inferomedial quadrant of the patella. Univariate analysis showed an association between male sex (p = 0.041), skeletal immaturity (p = 0.028), and decreased patellar tilt (p = 0.021) and patellar osteochondral fractures. Multivariate regression analysis identified male sex as an independent risk factor for osteochondral fractures (relative risk: 4.8, 95% confidence interval [CI]: 1.08–20.9, p = 0.039). No patients had recurrent dislocation at minimum 6-month follow-up. All patients with osteochondral fractures returned to sports at most recent follow up.ConclusionIn this study, 23% of pediatric patients with acute patellar dislocations have a concomitant patellar osteochondral fracture. The majority of patellar osteochondral fractures involve the inferomedial quadrant of the patella. Male sex is an independent risk factor for patellar osteochondral fractures, and skeletal immaturity is associated with patellar osteochondral fractures in this population.Level of evidenceLevel III.

Medial Patellofemoral Ligament Reconstruction

Background: Recurrentlateral patellar dislocation is a devastating condition associated with different pathologies, including medial patellofemoral ligament (MPFL) injury, increased tibial tubercle to trochlear groove (TT-TG) distance, and trochlear dysplasia. This video aims to provide an overview of isolated MPFL reconstruction in a patient with recurrent patellar dislocation and chronic MPFL injury. Indications: Isolated MPFL reconstruction is indicated for patients with recurrent lateral patellar instability following an initial trial of nonoperative management, in the absence of other contributing anatomic factors. Candidates for isolated MPFL reconstruction should have a TT-TG distance of <20 mm, and normal or Dejour type A trochlear morphology. Technique Description: Semitendinosus allograft is used to reconstruct the torn or attenuated MPFL. Following diagnostic arthroscopy, an incision is made over the medial border of the patella and dissection is carried through the skin and subcutaneous tissue to the fascia. Two K-wires are over-drilled and two 3.5-mm Arthrex SwiveLock anchors are placed. The allograft is prepared and whipstitched on both sides. The central portion of the graft is tide down to the anchors. A second incision is then made on the medial side of the knee over the epicondyle. Dissection is carried down to the fascia, and palpation is used to identify Schottles’ point. This is confirmed with fluoroscopy. An 8-mm drill bit is then used to drill to a depth of 60 mm on the femoral side. The grafts are passed one at a time through the femoral tunnel. The femoral side is fixed with an Arthrex BioComposite Interference Screw and the incisions are subsequently irrigated and closed in a layered fashion. Results: MPFL reconstruction demonstrates good functional and clinical outcomes with high rates of patient satisfaction and low rates of failure. A recent systematic review demonstrated an 84% rate of return to sport, improved postoperative outcomes, and pooled risks of recurrent instability and reoperation of less than 5% following isolated MPFL reconstruction. Conclusion: Isolated MPFL reconstruction should be considered for patients with recurrent patellar instability in the absence of other clinical risk factors. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Medial patellofemoral ligament reconstruction using superficial layer of quadriceps tendon autograft: A case series of three patients

IntroductionRecurrent patellar dislocation which caused by Medial Patellofemoral Ligament (MPFL) injury could be treated by MPFL reconstruction. This study evaluated MPFL reconstruction using superficial layer of quadriceps tendon autograft with knee functional outcome. MethodThree patients with recurrent patellar dislocation underwent MPFL reconstruction with superficial layer of quadriceps tendon autograft. The central quadriceps tendon was harvested at the superficial layer of the tendon. Then the proximal autograft routed medially on the periosteal hinge through vastus medial muscle. Functional outcome using IKDC, Tegner-Lysholm, and Modified Cincinnati were assessed pre and post-operative. ResultA good stability and painless knees were achieved. IKDC score, Tegner-Lysholm, and Modified Cincinnati was improved from pre-operative to post-operative. No severe postoperative complication was recorded. DiscussionThe superficial layer of quadriceps tendon has similar biomechanical and anatomical macroscopic attribute to native MPFL. The procedure using quadriceps tendon was simple and has fewer complication than using other autografts, such as hamstring tendon, adductor tendon, and patellar tendon. The one-year follow-up outcome of this procedure is excellent. ConclusionMPFL reconstruction with superficial layer of quadriceps tendon autograft was proven to prevent patellar dislocation without deteriorating quadriceps muscle strength and produced knee stabilization with functional score improvement.

Clinical outcome of Patella stability after fixation of Osteochondral fracture in Acute Primary Traumatic Patella Dislocation without MPFL Repair or Reconstruction

Introduction: Conservative management is advisable for acute primary traumatic patella dislocation (PTPD). Surgical treatment is reserved for osteochondral fractures (OCF), medial patello femoral ligament (MPFL) avulsion/tear, compound injuries, and any underlying bony abnormalities requiring correction. MPFL repair (at avulsed site) or reconstruction along with underlying bony correction in PTPD is controversial. The purpose of this study is to evaluate patella stability after fixation of OCF in PTPD without performing MPFL repair or reconstruction, even in the presence of any underlying bony abnormalities. Material and Methods: This is a retrospective study of eight patients who had PTPD with OCF along with MPFL injury who presented between 2016 and 2019. Pre-operative X-rays and MRI were done to assess the status of MPFL, identify the presence of OCF and to calculate Insall-Salvati index, Tibial Tuberosity-Trochlear groove distance and Trochlear dysplasia. All patients underwent surgery by open approach and OCF fixation by bioabsorbable pins or suture material. MPFL was neither repaired at avulsed site nor reconstructed and even no bony corrections were done. Results: Average size of OCF fragments is 15*7 mm and all involving medial facet of patella. Lysholm score improved significantly from 32.8 to 94.8 and Kujala score from 49.1 to 96 at the end of 6 months. None of the patient had patella instability till latest follow-up, average follow-up period is 4.5 years (3–6 years). Clinically, apprehension test was negative in all cases with full ROM. Post-operative imaging including X-ray and MRI showed complete healing of the OCF along with complete healing/regeneration of MPFL with same pre-existing bony abnormalities if present preoperatively. Conclusion: This study shows excellent patella stability and full knee function along with complete union of OCF and complete healing/regeneration of MPFL in PTPD even in the presence of underlying bony abnormality. Hence, in PTPD with OCF, there is no need to repair/reconstruct MPFL or to correct underlying bony pathology, only OCF fixation is required.

Chondral and Soft Tissue Injuries Associated to Acute Patellar Dislocation: A Systematic Review.

Introduction: Chondral and soft tissue injuries can be associated with first time patellar dislocation, but it is unclear how common they are, and which tissues are affected. A systematic review of the literature was performed to investigate the frequency, location, and extent of chondral and medial patellofemoral ligament (MPFL) injuries in patients following first time patellar dislocation. Methods: This systematic review was conducted according to the PRISMA guidelines. PubMed, Google Scholar, Embase, and Web of Science databases were accessed in November 2021. All the published clinical studies reporting the frequency, location, and extent of soft tissue lesions following first time patellar dislocation were accessed. Studies reporting data on habitual, congenital, or recurrent patellofemoral instability were excluded. Results: Data from 42 articles (2254 patients, mean age 21.6 ± 7.3 years) were retrieved. Ninety-eight percent of patients who experienced first time patellar dislocation demonstrated MPFL rupture at MRI. Forty-eight percent of MPFL ruptures were located at the patellar side, 34% at the femoral insertion site, and 18% in the midportion. Eighty-five percent of patients showed signs of patellar chondral damage at MRI, and trochlear chondral injuries were evidenced in 47% of patients. Intra-articular loose bodies were observed in 11.5% of patients. At arthroscopy, the medial facet and the crest of the patella more commonly exhibited chondral lesions than the lateral facet and femoral trochlea. Conclusions: Most patients suffer chondral damage and MPFL tears following after a first time patellar dislocation.

MPFL reconstruction and tibial tuberosity transposition in patients with patellar instability: May it troubleshots also trochlear dysplasia?

PurposeThis study aimed to highlight short- and medium-term outcomes of combined medial patello-femoral ligament (MPFL) reconstruction and anterior tibial tuberosity (ATT) transposition surgery in patients with recurrent patellar instability and different degrees of trochlear dysplasia.MethodsBetween January 2014 and May 2019, 25 patients with patellar instability underwent a surgical procedure combining the lowering/transposition of the ATT and the MPFL reconstruction. Each patient were preoperative assessed by Kujala score, International Knee Documentation Committee (IKDC), Tegner activity level scale. The assessment of instability predisposing factors was carried out with patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, sulcus angle, patellar tilt and MPFL injuries. Functional outcomes were evaluated with Kujala, IKDC and Tegner scores at 3, 6 and 12 months after surgery.ResultsThe average age of the patients was 20 years (range 13–43 years). Pre- operative Caton–Deschamps index was pathological in 10 (40%). Sulcus angle was elevated in 13 patients (52%) and TT-TG distance was irregular in 17 patients (68%). Trochlear dysplasia was present in 13 patients (9 type A, 3 type B, 1 type C according to Dejour’s Classification). No re-dislocation occurred during the follow-up. There was a significant increase in the Kujala, IKDC and Lysholm scores after 3, 6 and 12 months, and the results were compared for the different follow-up times and patient’s trochlear dysplasia degree.ConclusionThis prospective observational longitudinal study identified good clinical outcomes in patients who underwent MPFL reconstruction and ATT transposition for patellar instability. Finally, the different risk factors for patellar instability examined, particularly the presence of trochlear dysplasia, did not significantly influence the final functional results, which range from good to excellent without re-dislocation episodes.

Lateral Release With Tibial Tuberosity Transfer Alters Patellofemoral Biomechanics Promoting Multidirectional Patellar Instability

The purpose of this study was to develop and validate a finite element (FE) model of the patellofemoral (PF) joint to characterize patellofemoral instability, and to highlight the effect of lateral retinacular release in combination with tibial tuberosity transfer with respect to contact pressures (CP), contact area (CA), and kinematics during knee flexion. A comprehensive, dynamic FE model of the knee joint was developed and validated through parametric comparison of PF kinematics, CP, and CA between FE simulations and invitro, cadaveric experiments. Using this FE model, we characterized the effect of patellar instability, lateral retinacular release (LR), and tibial tuberosity transfer (TTT) in the setting of medial patellofemoral ligament injury during knee flexion. There was a high level of agreement in CP, CA, lateral patellar displacement, anterior patellar displacement, and superior patellar displacement between the FE model and the invitro data (Pvalues 0.19, 0.16, 0.81, 0.10, and 0.36, respectively). Instability conditions demonstrated the greatest CP compared to all of the other conditions. During all degrees of flexion, TTT and concomitant lateral release (TTT+ LR) decreased CP significantly. TTT alone shows a consistently lower CA compared to nonrelease conditions with subsequent lateral release further decreasing CA. The results of this study demonstrate that the FE model described reliably simulates PF kinematics and CP within 1 SD in uncomplicated cadaveric specimens. The FE model is able to show that tibial tubercle transfer in combination with lateral retinacular release markedly decreases patellofemoral CP and CA and increases lateral patellar displacement that may decrease bony stabilization of the patella within the trochlear groove and promote lateral patellar instability. The goal of surgical correction for patellar instability focuses on reestablishing normal PF kinematics. By developing an FE model that can demonstrate patient PF kinematics and the results of different surgical approaches, surgeons may tailor their treatment to the best possible outcome. Of the surgical approaches that have been described, the biomechanical effects of the combination of TTT with lateral retinacular release have not been studied. Thus, the FE analysis will help shed light on the effect of the combination of TTT with lateral retinacular release on PF kinematics.

Role of Magnetic Resonance Imaging in Study of the Patellofemoral Joint Morphological Abnormalities Predisposing to Patellar Instability

Objectives: The Patellofemoral joint (PFJ) is a complex joint structure with high functional and biomechanical requirements. The purpose of this study is to evaluate cause of patella-femoral joint instability with in-depth evaluation of influence of anatomical risk factors (AF), measurements and anatomical relationships of the patellofemoral joint and various pathologies causing medial patellofemoral ligament (MPFL) injury that contributes to the patellar maltracking using 1.5 Tesla magnetic resonance imaging. Materials and Methods: The present prospective study is carried out at department of radiology, shri M P Shah Medical College, Jamnagar. This is study of total 50 patients carried out in 12-month duration from July 2019 to June 2020, in which 50 patients aged between 8 - 68 years selected as study group presented with complaint symptoms of patellofemoral instability, knee pain and maltracking were examined and identified by an orthopaedic surgeon. Patients with the clinical suspicion of a PFJ maltracking were selected for subsequent MRI examination. Results: The age distribution in our study was in range of 8 years to 68 years with maximum population within 31 to 40 years range, 66 % were male and 34 % female. Their trochlear depth, sulcal angle, trochlear facet asymmetry, lateral inclination angle was found abnormal in 18 cases (36%), 8 (16%) showed patellar alta and 7 (14%) patella baja. Lateralization of patella (> 6 mm) was noted in 18 patients (36%), Medial patellofemoral ligament injuries were seen in 16 (32%) patients on MRI and kissing contusion 10 (20%) patients. A detailed understanding of the anatomy and pathology of the anterior knee compartment is essential for proper imaging interpretation and treatment management. Conclusion: Magnetic resonance (MR) imaging has been established as the method of choice, showing high accuracy in patellofemoral joint abnormalities. The present study aims to explore the role of MR imaging in diagnosing the various disorders located in anterior compartment of knee. Keywords: Joint instability, Patellofemoral joint, MPFL, MR imaging/diagnosis.

Magnetic Resonance Imaging Evaluation of Patellofemoral Joint.

Patellofemoral pain is the leading cause of knee pain in young adults. Magnetic resonance imaging plays an important role in early diagnosis of patellofemoral joint pathology. This study was carried out to evaluate the patellofemoral joint using magnetic imaging resonance and describe various predisposing factors for patellofemoral instability. The study was carried in Department of Radiology, BPKIHS over a period of six months from February 2020 to August 2020. All patients with clinical diagnosis of patellar instability were included and Magnetic resonance imaging was done using standard knee protocol and findings were noted on structured proforma. Analysis was done using statistical package for the social sciences version 20 applying simple descriptive statistical methods. A total of 60 patients who underwent MRI knee were analyzed, out of which 28(46.7%) patients were male while 32(53.3%) patients were female. 44 patients (58.3%) had various predisposing factors for patellar instability. The commonest predisposing factor was patellar subluxation (73.3%) followed by abnormal trochlear groove angle (58.3%) and patellar translation (increased tibia tubercle trochlear groove distance) (53.3%). Various MRI findings in our study were bone contusion (28 cases,46.7%), joint effusion (36 cases,60%), medial patellofemoral ligament injury (11cases ,18.3%), erosion of patellar cartilage (5 cases,8.3%), femoral cartilage erosion (3 cases,5%),loose bodies (2 cases,3.3%), subchondral edema (3 cases,5%) and meniscus injury (18 cases,30%). Magnetic resonance imaging is not only useful in assessing lesions of the bone, cartilage and ligaments of patellofemoral joint but also enables detection of various predisposing factors for patellofemoral instability.

Prevalence and Site of Medial Patellofemoral Ligament Injuries in Patients With Acute Lateral Patellar Dislocations: A Systematic Review and Meta-analysis.

Background:Medial patellofemoral ligament (MPFL) injuries are common in patients with acute lateral patellar dislocations, but the pattern of MPFL injuries is unclear, especially with respect to patient age.Purpose:The primary aim was to determine the prevalence of MPFL injuries according to the site of injury in patients with acute lateral patellar dislocations. The secondary aim was to compare the site of MPFL injuries in patients aged ≤16 versus >16 years.Study Design:Systematic review; Level of evidence, 4.Methods:A systematic literature search was performed with PubMed, Embase, and CINAHL to identify articles published from January 1, 1999, to May 31, 2019, that examined the site of MPFL injuries in patients with acute patellar dislocations. The study design, sample size, age at injury, technique used for diagnosing MPFL injuries (magnetic resonance imaging, ultrasound, and/or surgery), and prevalence and site of MPFL injuries were extracted from each study. The pooled estimate of the proportion of MPFL injuries at each site was calculated (femur, patella, midsubstance, and combined sites of injury) as well as proportions stratified by age group (≤16 and >16 years).Results:The literature search yielded 420 unique articles, of which 52 were screened for eligibility; of these, 17 were excluded. Thus, a total of 35 articles (2558 patients) were included in the final analysis. The overall prevalence of MPFL injuries was 94.7% (95% CI, 91.2%-96.8%). Most MPFL injuries occurred at the patella (37.1% [95% CI, 30.8%-43.9%]), followed by the femur (36.8% [95% CI, 31.0%-43.0%]), combined sites (25.1% [95% CI, 20.7%-30.1%]), and the midsubstance (15.6% [95% CI, 13.2%-18.4%]). In patients aged ≤16 years, most MPFL injuries occurred at the patella (39.3% [95% CI, 27.9%-51.9%]), and in patients aged >16 years, most MPFL injuries occurred at the femur (47.2% [95% CI, 40.6%-54.0%]).Conclusion:The prevalence of MPFL injuries in patients with acute patellar dislocations varied by site of injury and by age. MPFL injuries at the patella were most prevalent overall and in children and adolescents, and MPFL injuries at the femur were more prevalent in adults.

Gender-related differences in concomitant articular injuries after acute lateral patellar dislocation.

To explore the gender differences in the concomitant articular injuries after acute lateral patellar dislocation (LPD). Magnetic resonance images were prospectively analyzed in 166 patients after an acute LPD. Concomitant articular injuries included bone contusion, medial patellofemoral ligament (MPFL) injury, articular cartilage lesion, and vastus medialis obliquus (VMO) lesion. Statistical analyses were performed between the patient's gender and the incidence of concomitant articular injuries in adolescent and adult subgroups. The incidence of partial and complete MPFL tear in adolescent males and females were (45%, 50%) and (63.2%, 29.8%), respectively. Compared with adolescent females, adolescent males showed higher incidence of complete MPFL tear (P=0.049). The incidence of articular cartilage lesion of patella in adolescent males and females were 40% and 21.1%, respectively. Compared with adolescent females, adolescent males showed higher incidence of articular cartilage lesion of the patella (P=0.043). No correlations were identified in other injuries in the adolescent group. The incidence of partial and complete MPFL tear in adult males and females were (34.4%, 65.6%) and (56.8%, 37.8%), respectively. Compared with adult females, adult males showed higher incidence of complete MPFL tear (P=0.036). The incidence of articular cartilage lesion of patella in adult males and females were 56.3% and 32.4%, respectively. Compared with adult females, adult males showed higher incidence of articular cartilage lesion of patella (P=0.047). The incidence of VMO injury in adult males and females were 59.4% and 35.1%, respectively. Compared with adult females, adult males showed higher incidence of VMO injury (P=0.044). No correlations were identified in other injuries in the adult group. Compared with females, males predispose to complete MPFL tear and articular cartilage lesion of patella after acute LPD. Compared with female adults, male adults predispose to VMO injury.

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?

Concurrent Anterior Cruciate Ligament and Medial Patellofemoral Ligament Reconstruction: A Case Report and Literature Review

Anterior cruciate ligament (ACL) insufficiency in combination with patellar instability are rare occurrences and are difficult to treat. Failure to address patellar instability in such cases may place excessive strain on ACL graft leading to graft rupture. We present three such cases treated by concurrent ACL and medial patellofemoral ligament (MPFL) reconstruction with hamstring tendon autografts. Two patients had MRI evidence of MPFL injury and one patient had intact MPFL on MRI. All patients had good outcome without any residual instability at final follow-up.

Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients.

Patellofemoral instability is a common problem affecting children and adolescents, with recurrent instability often requiring surgical intervention. Medial patellofemoral ligament (MPFL) reconstruction has become a mainstay for the treatment of patellofemoral instability because of the biomechanical importance of the MPFL against lateral dislocation as well as the high frequency of MPFL injury following traumatic patellar dislocation. The concern in managing skeletally immature patients is the potential for injury to the distal femoral physis. Here, we highlight 2 techniques for MPFL reconstruction. The first technique utilizes a hamstring autograft. The steps include: Step 1: Harvest the semitendinosus graft from a 2-cm posteromedial incision with use of an open tendon harvester proximally and a closed tendon harvester distally. Step 2: Prepare the graft for double-bundle reconstruction, allowing for approximately 50 to 60 mm for the reconstructed MPFL and 15 to 20 mm for graft placement within the patella and femoral sockets. Step 3: Use a guidewire and reamer to create 2 patellar sockets approximately 15 mm long each. Step 4: Use a guidewire under fluoroscopy to position and create a femoral socket distal to the distal femoral physis approximately 15 mm long. Step 5: Fix the graft on the femur with use of a tenodesis screw, pass the graft through the soft-tissue space between the fascia and synovium to the superior half of the patella, then dock the free ends of the graft onto the 2 patellar sockets with "PEEK (polyetheretherketone) SwiveLocks (Arthrex)" while the knee is in 30° of flexion. We also review a second technique of docking the hamstring graft onto the adductor tubercle and suturing it proximally to the deep distal medial aspect of the quadriceps tendon. Although only a limited number of studies have reported the outcomes of MPFL reconstruction in skeletally immature patients, such studies have demonstrated a high return to preoperative level of sports activity and a reduced prevalence of recurrent patellar instability.