Medial patellotibial ligament and medial patellomeniscal ligament: anatomy, imaging, biomechanics, and clinical review

Combined medial patellofemoral ligament and medial patellotibial ligament reconstruction in recurrent patellar instability: A systematic review and meta-analysis

BACKGROUND

The medial patellofemoral ligament (MPFL), along with the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament, aid in the stabilization of the patellofemoral joint. Although the MPFL is the primary stabilizer and the MPTL is a secondary limiter, this ligament is critical in maintaining joint stability. There have been few studies on the combined MPFL and MPTL reconstruction and its benefits.

AIM

To look into the outcomes of combined MPFL and MPTL reconstruction in frequent patellar instability.

METHODS

By May 8, 2022, four electronic databases were searched: Medline (PubMed), Scopus, Web of Science, and Google Scholar. General keywords such as "patellar instability," "patellar dislocation," "MPFL," "medial patellofemoral ligament," "MPTL," and "medial patellotibial ligament" were co-searched to increase the sensitivity of the search.

RESULTS

The pooled effects of combined MPFL and MPTL reconstruction for Kujala score (12-mo follow-up) and Kujala score (24-mo follow-up) were positive and incremental, according to the findings of this meta-analysis. The mean difference between the Cincinnati scores was also positive, but not statistically significant. The combination of the two surgeries reduces pain. According to cumulative meta-analysis, the trend of pain reduction in various studies is declining over time.

CONCLUSION

The combined MPFL and MPTL reconstruction has good clinical results in knee function and, in addition to providing good control to maintain patellofemoral joint balance, the patient's pain level decreases over time, making it a valid surgical method for patella stabilization.

Individual Influence of Trochlear Dysplasia on Patellofemoral Kinematics after Isolated MPFL Reconstruction

INTRODUCTION

The influence of the MPFL graft in cases of patella instability with dysplastic trochlea is a controversial topic. The effect of the MPFL reconstruction as single therapy is under investigation, especially with severely dysplastic trochlea (Dejour types C and D). The purpose of this study was to evaluate the impact of trochlear dysplasia on patellar kinematics in patients suffering from low flexion patellar instability under weight-bearing conditions after isolated MPFL reconstruction.

MATERIAL AND METHODS

Thirteen patients were included in this study, among them were eight patients with mild dysplasia (Dejour type A and B) and five patients with severe dysplasia (Dejour type C and D). By performing a knee MRI with in situ loading, patella kinematics and the patellofemoral cartilage contact area could be measured under the activation of the quadriceps musculature in knee flexion angles of 0°, 15° and 30°. To mitigate MRI motion artefacts, prospective motion correction based on optical tracking was applied. Bone and cartilage segmentation were performed semi-automatically for further data analysis. Cartilage contact area (CCA) and patella tilt were the main outcome measures for this study. Pre- and post-surgery measures were compared for each group.

RESULTS

Data visualized a trending lower patella tilt after MPFL graft installation in both groups and flexion angles of the knee. There were no significant changes in patella tilt at 0° (unloaded pre-surgery: 22.6 ± 15.2; post-surgery: 17.7 ± 14.3; p = 0.110) and unloaded 15° flexion (pre-surgery: 18.9 ± 12.7; post-surgery: 12.2 ± 13.0; p = 0.052) of the knee in patients with mild dysplasia, whereas in patients with severe dysplasia of the trochlea the results happened not to be significant in the same angles with loading of 5 kg (0° flexion pre-surgery: 34.4 ± 12.1; post-surgery: 31.2 ± 16.1; p = 0.5; 15° flexion pre-surgery: 33.3 ± 6.1; post-surgery: 23.4 ± 8.6; p = 0.068). CCA increased in every flexion angle and group, but significant increase was seen only between 0°-15° (unloaded and loaded) in mild dysplasia of the trochlea, where significant increase in Dejour type C and D group was seen with unloaded full extension of the knee (0° flexion) and 30° flexion (unloaded and loaded).

CONCLUSION

This study proves a significant effect of the MPFL graft to cartilage contact area, as well as an improvement of the patella tilt in patients with mild dysplasia of the trochlea. Thus, the MPFL can be used as a single treatment for patient with Dejour type A and B dysplasia. However, in patients with severe dysplasia the MPFL graft alone does not significantly increase CCA.

Patellofemoral Instability Part I: Evaluation and Nonsurgical Treatment

Patellofemoral instability (PFI) is a prevalent cause of knee pain and disability. It affects mostly young females with an incidence reported as high as 1 in 1,000. Risk factors for instability include trochlear dysplasia, patella alta, increased tibial tubercle-to-trochlear groove distance, abnormal patella lateral tilt, and coronal and torsional malalignment. Nonsurgical and surgical options for PFI can treat the underlying causes with varied success rates. The goal of this review series was to synthesize the current best practices into a concise, algorithmic approach. This article is the first in a two-part review on PFI, which focuses on the clinical and radiological evaluation, followed by nonsurgical management. The orthopaedic surgeon should be aware of the latest diagnostic protocol for PFI and its nonsurgical treatment options, their indications, and outcomes.

Evaluation of recurrent dislocation of the patella in children with MRI: Goldthwait technique combined with lateral release, and VMO advancement-a retrospective study of 85 knees

PURPOSE

There are certain risk factors responsible for patella instability that should be identified before choosing the most appropriate treatment.

METHODS

We evaluated 83 skeletally immature patients who, after two or more patellar dislocation episodes, underwent surgical treatment to address the condition of patellar instability. Each patient was evaluated for patellar instability risk factors using the Balcarek patellar instability severity score. Evaluation of patellar instability included knee MRI to systematically identify anatomical risk factors. The preoperative and postoperative clinical evaluation included the modified Cincinnati score and the Kujala score. The Roux-Goldthwait technique combined with lateral retinaculum release and the advancement of the vastus medialis oblique (VMO) was performed on all knees.

RESULTS

The mean patient age at the time of surgery was 12.2 ± 1.59 years (range 8-14 years). The average follow-up was 4.72 ± 1.37 (range 3-8) years. Trochlear dysplasia (decreased trochlear depth), the most common anatomical risk factor, was identified in 71 knees (83.5%). The modified Cincinnati score increased from 58.46 ± 8.75 (range 49-76) points to 94.07 ± 2.88 (range 88-98) postoperatively. The mean Kujala scores increased from 58.51 ± 8.94 (range 49-76) points to 93.66 ± 2.65 (range 87-98) postoperatively. The two-tailed P value was less than 0.0001. The patients were followed until their skeletal maturation, without reporting any incidents of patella dislocation, except one.

CONCLUSION

The Roux-Goldthwait technique combined with lateral retinaculum release, and the advancement of VMO, can restore patellar tracking and can decrease the probability of another dislocation. It was an effective treatment in skeletally immature patients who had two or more episodes of patellar dislocation.

LEVEL OF EVIDENCE

IV.

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.

Online Rehabilitation Protocols for Medial Patellofemoral Ligament Reconstruction With and Without Tibial Tubercle Osteotomy Are Variable Among Institutions

Purpose

To compare and contrast the various rehabilitation protocols for medial patellofemoral ligament (MPFL) reconstruction and MPFL reconstruction plus tibial tubercle osteotomy (TTO) published online by academic orthopaedic surgery residency programs and private practice institutions throughout the United States.

Methods

We performed a systematic electronic search of MPFL reconstruction rehabilitation protocols in academic orthopaedic surgery residency programs in the United States using Google’s search engine (www.google.com) based on the Fellowship and Residency Electronic Interactive Database Access System (FREIDA). Private practice organizations publishing MPFL reconstruction or MPFL reconstruction–TTO rehabilitation protocols that were found on the first page of search results were also included, but no comprehensive search for private practice protocols was performed. Protocols specifying an MPFL reconstruction with TTO were included for separate review because of altered weight-bearing status postoperatively. A list of comparative criteria was created to assess the protocols for the presence and timing of the various rehabilitation components.

Results

From the list of 189 U.S. academic residency programs, as well as additional private practice protocols found in the Google search, 38 protocols were included for review (31 protocols for isolated MPFL reconstruction and 7 protocols for MPFL reconstruction plus TTO). A return to full range of motion by week 6 was recommended by 15 (48.4%) of the isolated MPFL reconstruction protocols and 6 (85.7%) of the MPFL reconstruction–TTO protocols. Six weeks of knee brace wear was recommended by 13 isolated MPFL reconstruction protocols (43.3%) and 4 MPFL reconstruction–TTO protocols (57.1%). Moreover, 6 isolated MPFL reconstruction protocols (19.4%) and 3 MPFL reconstruction–TTO protocols (42.9%) recommended use of a patellar stabilizing brace postoperatively.

Conclusions

There is substantial variability among rehabilitation protocols after MPFL reconstruction, as well as MPFL reconstruction plus TTO, including postoperative range of motion, weight-bearing status, and time until return to sport. Furthermore, many online protocols from academic orthopaedic surgery residency programs and private practices in the United States fail to mention several of these parameters, most notably functional testing to allow patients to return to sport.

Clinical Relevance

Proper rehabilitation after MPFL reconstruction with or without TTO is an important factor to a patient’s postoperative outcome. This study outlines the variability in online rehabilitation protocols after MPFL reconstruction with or without TTO published online by academic residency programs and private practice institutions.

Combined Medial Patellofemoral Ligament and Medial Patellotibial Ligament Reconstruction for Recurrent Lateral Patellar Dislocation in Flexion

Recurrent lateral patellar dislocation can be a challenging entity to manage. It results from an imbalance between the restraints to lateralization of the patella and the forces applied to the patella within the biomechanical environment of the knee. The medial patellofemoral ligament has been recognized as the most important static soft-tissue restraint. However, the medial patellotibial ligament and medial patellomeniscal ligament are important for patellar stability at higher degrees of knee flexion. Lateral patellar dislocation in flexion poses a particularly challenging clinical entity with a combination of unique characteristics that need to be addressed to achieve optimal patellar tracking and stability. In this technical note, we describe a combined medial patellofemoral ligament and medial patellotibial ligament reconstruction technique to address lateral patellar dislocation in flexion.

The majority of patellar avulsion fractures in first-time acute patellar dislocations included the inferomedial patellar border that was different from the medial patellofemoral ligament attachment

PURPOSE

Accurate assessment of the locations of patellar avulsion fractures in acute patellar dislocations is clinically relevant for decision making for treatment. The study aim was to classify the locations of patellar avulsion fractures with a focus on the ligament attachments of medial stabilizing structures.

METHODS

Out of 131 first-time acute traumatic patellar dislocations, 61 patients had patellar fractures. Subsequently, 10 patients with isolated osteochondral fractures of the articular surface in the patella were excluded. Finally, 51 patients (34 females and 17 males, average age: 18.5 years, 95% CI 16.1-20.9) were included in the study cohort. Based on the locations of the patellar attachment, the patients were divided into three groups: the superior group [medial patellofemoral ligament (MPFL) attachment], inferior group [medial patellotibial ligament (MPTL)/medial patellomeniscal ligament (MPML) attachment], and mixed group.

RESULTS

In the patellar avulsion group (51 patients), the superior group, mixed group, and inferior group contained 8/51 (16%), 12/51 (24%), and 31/51 (61%) patients, respectively.

CONCLUSIONS

This study showed that 84% of the patellar avulsion fractures were located in the inferomedial patellar border, which consisted of MPTL/MPML attachments that were clearly different from the true "MPFL" attachment at the superomedial patellar border. In terms of the clinical relevance, the acute surgical repair of MPTL/MPML attachments in the inferomedial patellar border may not sufficiently control the patella if optimal management of the MPFL is not performed.

LEVEL OF EVIDENCE

IV.

Combined medial patellofemoral and medial patellotibial reconstruction for patellar instability: a PRISMA systematic review

BACKGROUND

The medial patellofemoral ligament (MPFL) works in association with the medial patellotibial ligament (MPTL) and the medial patellomeniscal ligament (MPML) to impart stability to the patellofemoral joint. The anatomy and biomechanical characteristics of the MPFL have been well described but little is known about the MPTL and MPML. Several reconstruction procedures of the MPFL with semitendinosus, gracilis, patellar and quadriceps tendons, allografts and synthetic grafts have been described. No clear superiority of one surgical technique over another is evident.

METHODS

A systematic review of the literature was conducted using PRISMA guidelines. Inclusion criteria were articles that reported clinical outcomes of combined reconstruction of MPTL and MPFL. The methodological quality of the articles was determined using the modified Coleman Methodology Score (CMS).

RESULTS

Nine articles were included, reporting the clinical outcomes of 197 operated knees. The surgical procedures described include hamstrings grafting and transfer of the medial patellar and quadriceps tendons with or without bony procedures to reconstruct the MPTL in association with the MPFL. Overall, good and excellent outcomes were achieved. The median CMS is 70.6 ± 14.4 (range 38 to 84).

CONCLUSION

Different techniques are reported, and outcomes are good with low rates of recurrence. The quality of the articles is variable, ranging from low to high. Appropriately powered randomized controlled trials are needed to better understand what the adequate indications for surgery in patients with patellar instability and clinical outcomes are. Combined reconstruction of MPFL and MPTL leads to favourable clinical outcomes, supporting its role as a valid surgical procedure for patellar stabilization.

Medial Patellotibial Ligament Reconstruction Improves Patella Tracking When Combined With Medial Patellofemoral Reconstruction: An In Vitro Kinematic Study

PURPOSE

To investigate the isolated and combined effects of medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) deficiency and reconstruction on patellofemoral kinematics.

METHODS

Sixteen matched-paired female cadaveric knee specimens with a mean age of 53.5 years (range, 26-65) were tested in 5 conditions: (1) intact, (2) MPFL or MPTL cut, (3) MPFL and MPTL combined cut, (4) MPFL or MPTL reconstruction, and (5) MPFL and MPTL combined reconstruction. Dynamic testing allowed continuous analysis of kinematics from 0° to 90° of knee flexion. Knees were also tested statically using a lateral load of 45 N at 0°, 30°, 60°, and 90° of flexion. In both dynamic and static loading tests, a motion capture system detected patellar position for each testing state to distinguish changes in patellar kinematics. Random-intercepts linear mixed-effects models were used to compare patellar kinematics.

RESULTS

The MPFL is the primary restraint to lateral translation of the patella at all knee flexion angles. MPTL deficiency alone did not create significant patella instability, but further increased instability when the MPFL was deficient. Isolated MPFL and combined reconstruction provided improved stability. Through full range of motion native patella tracking was best recreated with combined ligament reconstruction.

CONCLUSIONS

The MPFL plays the greatest role in medial patellar stability, but the MPTL appears to have an influence on patella tracking. This study provides further understanding to the impact of the MPFL and MPTL on patellofemoral motion with implications for reconstruction to improve stability and optimize patellofemoral tracking.

CLINICAL RELEVANCE

This study provides further understanding of the role of the MPFL and MPTL on patellofemoral motion with implications for reconstruction to improve stability and optimize patellofemoral tracking.

Scoring system for optimal management of acute traumatic patellar dislocation: A multicenter study

BACKGROUND

In first-time acute traumatic patellar dislocations, numerous anatomic and clinical factors are complicatedly associated and should be comprehensively considered for the optimal management of conservative or surgical intervention. The purpose of this study was to establish a scoring system, using a concept that is not complicated and easily used in clinic.

METHODS

Of 131 first-time acute traumatic patellar dislocations, 81 patients (51 females, 30 males) with an average age of 19.6 (95%CI, 17.5-21.6) years and an average follow-up duration of 17.1 (95% CI, 12.3-21.9) months, who underwent conservative treatment after first-time dislocations, were reviewed. Based on the odds ratios applying logistic regression analysis, the scoring system was established.

RESULTS

The scoring system (total: 10 points) had simple composition of age <20 (2 points), sports injury (1 points), hemarthrosis (1 points), and image findings of a bony fragment (3 points), lateral shift of the patella (1 points), and trochlear dysplasia (2 points). A threshold score of 6.5 was determined using the area under receiver operating characteristic curve of 0.893 (p < 0.0001). In logistic regression analysis, a score of ≥7 was shown to be a dominant factor for recurrence (OR = 27.1, p < 0.0001). Furthermore, the association between the score and recurrence risk was as follows: a score of ≤4 = low risk (1/21 cases, 5%); a score of 5-7 = medium risk (13/27 cases, 48%); a score of ≥8 = high risk (30/33 cases, 91%).

CONCLUSIONS

Based on the simple scoring system, patients who scored ≥8 were considered suitable for surgical treatment because of the high rate of recurrence, whereas those who scored ≤4 were considered suitable for conservative treatment because of the low rate of recurrence.

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.

Concepts of the Distal Medial Patellar Restraints: Medial Patellotibial Ligament and Medial Patellomeniscal Ligament

The important medial patellar ligamentous restraints to lateral dislocation are the proximal group (the medial quadriceps tendon femoral ligament and the medial patellofemoral ligament) and the distal group [medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML)]. The MPTL patellar insertion is at inferomedial border of patella and tibial insertion is in the anteromedial tibia. The MPML originates in the inferomedial patella, right proximal to the MPTL, inserting in the medial meniscus. On the basis of anatomy and biomechanical studies, the MPTL and MPML are more important in 2 moments during knee range of motion: terminal extension, when it directly counteracts quadriceps contraction. In a systematic review on MPTL reconstructions 19 articles were included detailing the clinical outcomes of 403 knees. All were case series. Overall, good and excellent outcomes were achieved in >75% of cohorts in most studies and redislocations were <10%, with or without the association of the medial patellofemoral ligament. The MPTL is a relevant additional tool to proximal restraint reconstruction in select patient profiles; however, more definitive clinical studies are necessary to better define surgical indications.

A Knee Size-Independent Parameter for Malalignment of the Distal Patellofemoral Joint in Children

Introduction

Patellar instability (PI) is a common finding in children. Current parameters describing patellofemoral joint alignment do not account for knee size. Additionally, most parameters utilize joint-crossing tibiofemoral landmarks and are prone to errors. The aim of the present study was to develop a knee size-independent parameter that is suitable for pediatric or small knees and determines the malpositioning of the distal patellar tendon insertion solely utilizing tibial landmarks.

Methods

Sixty-one pediatric knees were included in the study. The tibial tubercle posterior cruciate ligament distance (TTPCL) was measured via magnetic resonance imaging (MRI). The tibial head diameter (THD) was utilized as a parameter for knee size. An index was calculated for the TTPCL and THD (TTPCL/THD). One-hundred adult knees were analyzed to correlate the data with a normalized cohort.

Results

The THD was significantly lower in healthy females than in males (69.3 mm ± 0.8 mm vs. 79.1 mm ± 0.7 mm; p < 0.001) and therefore was chosen to serve as a knee size parameter. However, no gender differences were found for the TTPCL/THD index in the healthy adult study cohort. The TTPCL/THD was significantly higher in adult PI patients than in the control group (0.301 ± 0.007 vs. 0.270 ± 0.007; p=0.005). This finding was repeated in the PI group when the pediatric cohort was analyzed (0.316 ± 0.008 vs. 0.288 ± 0.010; p=0.033).

Conclusion

The TTPCL/THD index represents a novel knee size-independent measure describing malpositioning of the distal patellar tendon insertion determined solely by tibial landmarks.

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.

Proximal medial patellar restraints and their surgical reconstruction

Reconstruction of the medial patellofemoral ligament (MPFL) has been increasing as a surgical solution for treatment of recurrent lateral patellofemoral dislocation. Recent attention has been given to fibers extending from the femur to the quadriceps tendon, proximal to the MPFL, termed the medial quadriceps tendon-femoral ligament. This article briefly reviews the proximal medial patellar restraints and surgical procedures for their reconstruction.

Editorial Commentary: What Is the Optimal Management of First and Recurrent Patellar Instability? Patellofemoral Instability Management Continues to Evolve

Patellar instability patients may present for evaluation after their first instability episode or after recurrent episodes. Current management differs for these 2 groups. The accepted "common denominator" of patellar instability is the medial patellofemoral ligament, or medial patellar restraints, to be more all-encompassing. These patients often have multiple contributing comorbidities (e.g., trochlear dysplasia, patellar alta, excessive lateral position of tibial tubercle). Historically, the recommended treatment for a first-time patellar dislocation was nonoperative because medial soft tissue repairs had not been proven more effective. Indications for primary repair of the medial patellar restraints are a single discrete tear identified on magnetic resonance imaging. In the case of recurrent patellar instability, medial patellofemoral ligament reconstruction, rather than repair/reef, has been the recommended approach. The keys to reconstruction remain: honor the anatomy and avoid overconstraint of the patella. For first time dislocation patients with trochlear dysplasia, patellar alta, and age <25 years, recurrent instability is common.

Reconstruction of the medial patellotibial ligament results in favorable clinical outcomes: a systematic review

PURPOSE

The medial patellotibial ligament (MPTL), the medial patellofemoral ligament (MPFL), and the medial patellomeniscal ligament (MPML) support the stability of the patellofemoral joint. The purpose of this systematic review was to report the surgical techniques and clinical outcomes of the repair or reconstruction of the MPTL in isolation or concomitant with the MPFL and/or other procedures.

METHODS

A systematic review of the literature was conducted. Inclusion criteria were articles in the English language that reported clinical outcomes of the reconstruction of the MPTL in isolation or in combination with the MPFL and/or other procedures. Included articles were then cross-referenced to find additional journal articles not found in the initial search. The methodological quality of the articles was determined using the Coleman Methodology Score.

RESULTS

Nineteen articles were included detailing the clinical outcomes of 403 knees. The surgical procedures described included hamstrings tenodesis with or without other major procedures, medial transfer of the medial patellar tendon with or without other major procedures and the reconstruction of the MPTL in association with the MPFL. Overall, good and excellent outcomes were achieved in > 75% of cohorts in most studies and redislocations were < 10%, with or without the association of the MPFL. An exception was one study that reported a high failure rate of 82%. Results were consistent across different techniques. The median CMS for the articles was 66 out of 100 (range 30-85).

CONCLUSION

Across different techniques, the outcomes are good with low rates of recurrence, with one article reporting a high rate of recurrence. Quality of the articles is variable, from low to high. Randomized control trials are needed for a better understanding of the indications, surgical techniques, and clinical outcomes. This systematic review suggests that the reconstruction of the MPTL leads to favorable clinical outcomes and supports the role of the procedure as a valid surgical patellar stabilization procedure.

LEVEL OF EVIDENCE

IV: systematic review of level I-IV studies.

Treatment of recurrent patellar dislocation via knee arthroscopy combined with C-arm fluoroscopy and reconstruction of the medial patellofemoral ligament

Recurrent patellar dislocations were treated via knee arthroscopy combined with C-arm fluoroscopy, and reconstruction of the medial patellofemoral ligaments. Between October 2013 and March 2017, 52 cases of recurrent patellar dislocation [27 males and 25 females; age, 16-47 years (mean, 21.90 years)] were treated. Arthroscopic exploration was performed and patellofemoral joint cartilage injuries were repaired. It was subsequently determined whether it was necessary to release the lateral patellofemoral support belt. Pre-operative measurements were used to decide whether tibial tubercle osteotomy was required. Medial patellofemoral ligaments were reconstructed using autologous semitendinosus tendons. Smith and Nephew model 3.5 line anchors were used to double-anchor the medial patellofemoral margin. On the femoral side, the medial patellofemoral ligament was fixed using 7-cm, absorbable, interfacial compression screws. All cases were followed for 1-40 months (average, 21 months). The Q angle, tibial tuberosity trochlear groove distance, Insall-Salvati index, patellofemoral angle, lateral patellofemoral angle and lateral shift were evaluated on X-Ray images using the picture archiving and communication system. Subjective International Knee Documentation Committee (IKDC) knee joint functional scores and Lysholm scores were recorded. Post-operative fear was absent, and no patellar re-dislocation or re-fracture was noted during follow-up. At the end of follow-up, the patellofemoral angle (0.22±4.23°), lateral patellofemoral angle (3.44±1.30°), and lateral shift (0.36+0.14°) differed significantly from the pre-operative values (all, P<0.05). Furthermore, IKDC and Lysholm scores (87.84+3.74 and 87.48+3.35, respectively) differed significantly from the pre-operative values (both, P<0.05). These findings suggest that, in the short term, recurrent patellar dislocation treatment via knee arthroscopy combined with C-arm fluoroscopy and reconstruction of the medial patellofemoral ligament was effective.

The medial patellofemoral complex

PURPOSE OF REVIEW

The purpose of this review is to describe the current understanding of the medial patellofemoral complex, including recent anatomic advances, evaluation of indications for reconstruction with concomitant pathology, and surgical reconstruction techniques.

RECENT FINDINGS

Recent advances in our understanding of MPFC anatomy have found that there are fibers that insert onto the deep quadriceps tendon as well as the patella, thus earning the name "medial patellofemoral complex" to allow for the variability in its anatomy. In MPFC reconstruction, anatomic origin and insertion points and appropriate graft length are critical to prevent overconstraint of the patellofemoral joint. The MPFC is a crucial soft tissue checkrein to lateral patellar translation, and its repair or reconstruction results in good restoration of patellofemoral stability. As our understanding of MPFC anatomy evolves, further studies are needed to apply its relevance in kinematics and surgical applications to its role in maintaining patellar stability.

Biomechanical Evaluation of the Medial Stabilizers of the Patella

BACKGROUND

Quantification of the biomechanical properties of each individual medial patellar ligament will facilitate an understanding of injury patterns and enhance anatomic reconstruction techniques by improving the selection of grafts possessing appropriate biomechanical properties for each ligament.

PURPOSE

To determine the ultimate failure load, stiffness, and mechanism of failure of the medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), and medial patellomeniscal ligament (MPML) to assist with selection of graft tissue for anatomic reconstructions.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twenty-two nonpaired, fresh-frozen cadaveric knees were dissected free of all soft tissue structures except for the MPFL, MPTL, and MPML. Two specimens were ultimately excluded because their medial structure fibers were lacerated during dissection. The patella was obliquely cut to test the MPFL and the MPTL-MPML complex separately. To ensure that the common patellar insertion of the MPTL and MPML was not compromised during testing, only one each of the MPML and MPTL were tested per specimen (n = 10 each). Specimens were secured in a dynamic tensile testing machine, and the ultimate load, stiffness, and mechanism of failure of each ligament (MPFL = 20, MPML = 10, and MPTL = 10) were recorded.

RESULTS

The mean ± SD ultimate load of the MPFL (178 ± 46 N) was not significantly greater than that of the MPTL (147 ± 80 N; P = .706) but was significantly greater than that of the MPML (105 ± 62 N; P = .001). The mean ultimate load of the MPTL was not significantly different from that of the MPML ( P = .210). Of the 20 MPFLs tested, 16 failed by midsubstance rupture and 4 by bony avulsion on the femur. Of the 10 MPTLs tested, 9 failed by midsubstance rupture and 1 by bony avulsion on the patella. Finally, of the 10 MPMLs tested, all 10 failed by midsubstance rupture. No significant difference was found in mean stiffness between the MPFL (23 ± 6 N/mm²) and the MPTL (31 ± 21 N/mm²; P = .169), but a significant difference was found between the MPFL and the MPML (14 ± 8 N/mm²; P = .003) and between the MPTL and MPML ( P = .028).

CONCLUSION

The MPFL and MPTL had comparable ultimate loads and stiffness, while the MPML had lower failure loads and stiffness. Midsubstance failure was the most common type of failure; therefore, reconstruction grafts should meet or exceed the values reported herein.

CLINICAL RELEVANCE

For an anatomic medial-sided knee reconstruction, the individual biomechanical contributions of the medial patellar ligamentous structures (MPFL, MPTL, and MPML) need to be characterized to facilitate an optimal reconstruction design.