Medial Patellofemoral Ligament, Medial Patellotibial Ligament, and Medial Patellomeniscal Ligament: Anatomic, Histologic, Radiographic, and Biomechanical Study

Patellofemoral instability part 1 (When to operate and soft tissue procedures): State of the art

Patellofemoral instability is usually initially treated non-operatively. Surgery is considered in patients with recurrent patellar dislocation and after a first-time patellar dislocation in the presence of either an associated osteochondral fracture or high risk of recurrence. Stratifying the risk of recurrence includes evaluating risk factors such as age, trochlear dysplasia, contralateral dislocation, and patellar height. Surgery with soft tissue procedures includes restoring the medial patellar restraints and balancing the lateral side of the joint. Reconstruction of the medial patellofemoral ligament is the most frequent way of addressing the medial soft tissues in patients with patellofemoral instability. Meanwhile, lateral tightness can be achieved by lateral retinaculum lengthening or release. Approaching patellofemoral instability in a patient-specific approach, combined with a shared decision-making process with the patient/family, will guide surgeons to the deliver optimal care for the patellar instability patient.

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.

Medial patellofemoral ligament reconstruction in skeletally immature patients without correction of bony risk factors leads to acceptable outcomes but higher failure rates

OBJECTIVES

To report outcomes and re-dislocation rates of medial patellar stabilizers reconstruction without bone procedures for correction of anatomical risk factors for patellar instability in skeletally immature patients; to compare isolated medial patellofemoral ligament (MPFL) reconstruction to combined MPFL and medial patellotibial ligament (MPTL) reconstruction in this population.

METHODS

Patients with open physis and bone abnormalities including patella alta and/or increased tibial tubercle-trochlear groove (TT-TG) distance and/or trochlear dysplasia underwent MPFL reconstruction, either isolated or associated with MPTL reconstruction. Preoperative, 1-year follow-up and the latest follow-up (5 years minimum) data were collected. Radiological and clinical evaluations were conducted, with special attention to failure rate. Comparison of results from isolated MPFL and combined MPFL/MPTL reconstructions was performed.

RESULTS

Twenty-nine patients were included, 19 in the isolated MPFL group (median 14 years old; follow-up 5.8 ​± ​1.7 years) and 10 in the combined MPFL/MPTL group (median 13.5 years old; follow-up 5.2 ​± ​1.4 years). Kujala and Tegner scores increased over time, although without statistically significant differences between the two groups at the latest follow-up (p ​= ​0.840 and p ​> ​0.999, respectively). During follow-up, 5 of 19 (26.3%) isolated MPFL and 2 of 10 (20%) MPFL/MPTL reconstructions experienced recurrence of patellar dislocation (p ​> ​0.999). Trochlear dysplasia type D (p ​= ​0.028), knee rotation (p ​= ​0.009) and lateral patellar tilt angle (p ​= ​0.003) were associated with patellar instability recurrence. The isolated MPFL group showed increased laxity on physical exam at the latest follow-up compared to the 1-year follow-up (patellar glide test (p ​= ​0.002), patellar tilt test (p ​= ​0.042) and subluxation in extension (p ​= ​0.019). This increased laxity was not observed in the MPFL/MPTL group (p ​> ​0.999). Comparing both groups, the glide test was significantly better in the combined MPFL/MPTL group in comparison to the isolated MPFL reconstruction group at the latest follow-up (p ​= ​0.021).

CONCLUSION

MPFL reconstruction in isolation or combined with MPTL reconstruction in skeletally immature patients with additional uncorrected anatomical patellofemoral abnormalities leads to acceptable clinical outcomes within a minimum of 5 years follow-up, although has a high failure rate of 24.1%. Addition of a MPTL reconstruction to the MPFL may result in decreased patellar laxity on physical exams, as demonstrated by better patellar glide test, patellar tilt test and subluxation in extension.

LEVEL OF EVIDENCE

Level III; retrospective cohort study.

Combined Medial Patellofemoral Ligament, Medial Quadriceps Tendon-Femoral Ligament, and Medial Patellotibial Ligament Reconstruction for Patellar Instability: A Technical Note

Lateral patellar dislocations often occur in a young, athletic population of recurrent dislocators with generalized laxity and an interest in returning to an active lifestyle. A recent appreciation for the distal patellotibial complex has directed surgeons toward attempting to re-create the native anatomy and knee biomechanics during medial patellar reconstructive procedures. By reconstructing the medial patellotibial ligament (MPTL) in addition to the medial patella-femoral ligament (MPFL) and medial quadriceps tendon-femoral ligament (MQTFL), the current article describes a potentially more stable construct that can be utilized in patients with subluxation with the knee in full extension, patellar instability with the knee in deep flexion, genu recurvatum, and generalized hyperlaxity. Additionally, the current technique utilizes a tibialis anterior allograft. The purpose of this Technical Note is to describe, in detail, the current authors' technique for a combined MPFL, MQTFL, and MPTL reconstruction.

Lateral Patellar Instability

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Patellar instability represents a common problem with an evolving understanding and multifactorial pathoetiology. Treatment plans should be based on the identification of contributing anatomical factors and tailored to each individual patient.

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Risks for recurrent instability are dependent on several patient-specific factors including patella alta, increased tibial tubercle-to-trochlear groove (TT-TG) distance, trochlear dysplasia, younger skeletal age, and ligamentous laxity.

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Cartilage or osteochondral lesions and/or fractures are commonly observed in first-time patellar dislocation, and magnetic resonance imaging (MRI) should be strongly considered. Advanced imaging modalities, such as computed tomography (CT) or MRI, should also be obtained preoperatively to identify predisposing factors and guide surgical treatment.

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Medial patellofemoral ligament (MPFL) reconstruction with anatomical femoral tunnel positioning is associated with lower recurrence rates compared with MPFL repair and has become a common and successful reconstructive surgical option in cases of instability.

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Lateral retinacular tightness can be addressed with lateral retinacular release or lengthening, but these procedures should not be performed in isolation.

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Tibial tubercle osteotomy is a powerful reconstructive tool in the setting of underlying skeletal risk factors for instability and can be of particular benefit in the presence of increased TT-TG distance (>20 mm), and/or in the setting of patella alta.

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The indications for trochleoplasty are still developing along with the clinical evidence, but trochleoplasty may be indicated in some cases of severe trochlear dysplasia. Several surgical techniques have indications in specific clinical scenarios and populations, and indications, risks, and benefits to each are progressing with our understanding.

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Combined femoral derotational osteotomy and MPFL reconstruction can be considered for patients with a femoral anteversion angle of >30° to improve patient outcomes and reduce recurrence rates.

Abnormal patellar loading may lead to femoral trochlear dysplasia: an experimental study of patellar hypermobility and patellar dislocation in growing rats

BACKGROUND

This animal study aimed to explore the effects of patellar hypermobility and patellar dislocation on the developing femoral trochlea.

METHODS

Seventy-two 3-week-old Wistar rats were randomly divided into three groups. The sham group (SG) underwent simple incision and suture of the skin and subcutaneous tissue; the patellar hypermobility group (PHG) underwent medial and lateral retinacular release and pie-crusting technique for the patellar ligament; the patellar dislocation group (PDG) underwent plication of the medial patellofemoral retinaculum. Twelve rats in each group were euthanized at 3 and 6 weeks postoperatively, respectively, and specimens were collected. The bony sulcus angle (BSA), cartilaginous sulcus angle (CSA), trochlear sulcus depth (TSD), and thickness of the cartilage on the lateral facet (CTL), medial facet (CTM), and center (CTC) of the trochlea were measured on hematoxylin and eosin-stained sections.

RESULTS

In the PHG and PDG, the femoral condyles became blunt, the trochlear groove became shallower, and cartilage became thicker compared with the SG. Compared with the SG, the PHG and PDG had significantly larger BSA and CSA values at 3 (p < 0.05) and 6 weeks (p < 0.005), and a significantly shallower TSD (p < 0.05). At 3 weeks, all cartilage thicknesses in the PHG and the CTC and CTM in the PDG were significantly thinner than in the SG (PHG vs. SG: p = 0.009 for CTL, p < 0.001 for CTM, p = 0.003 for CTC; PDG vs. SG: p = 0.028 for CTC, p = 0.048 for CTM). At 6 weeks, the CTC was thicker in the PHG and PDG than the SG (PHG vs. SG: p = 0.044; PDG vs. SG: p = 0.027), and the CTL was thinner in the PDG than the SG (p = 0.044).

CONCLUSION

Patellar hypermobility and patellar dislocation may result in trochlear dysplasia that worsens with age. Excessive or insufficient loading leads to trochlear dysplasia.

After MPFL reconstruction, femoral tunnel widening and migration increase with poor tunnel positioning and are related to poor clinical outcomes

PURPOSE

Isolated MPFL reconstruction (iMPFLR) is increasingly used for the surgical treatment of treatment for recurrent patella dislocation. The purpose of this study was to evaluate the influence of tunnel widening and migration on clinical outcomes after iMPFL using a CT-scannographic analysis at 6 months postoperatively.

METHODS

One hundred and sixty patients (91 females for 69 males) with an average age of 23 years [14-54] who underwent iMPFLR and had an evaluation scan at 6 months postoperatively were evaluated with a mean follow-up of 97 ± 89 months [12 to 166]. Functional International Knee Documentation Committee (IKDC) Score, Kujala score, and joint mobility were assessed preoperatively, at 6 months and at the latest follow-up. The IKDC and Kujala scores were expressed as the difference between pre- and postoperative scores (dIKDC and dKujala). The position of the femoral tunnel was assessed according to the Schöttle criteria on post-operative radiographic profiles. Tunnel widening (at three levels of measurement) and the migration of the center of the tunnel were studied on a CT-scan analysis at 6 months. Any correlation and regression between the evolution of the clinical scores and the measured scannographic parameters were investigated. The relationships between tunnel position and tunnel changes were also studied.

RESULTS

Between pre- and post-op, the IKDC (45 ± 13 to 80 ± 15, p < 0.001) and Kujala (55 ± 11 to 87 ± 12, p < 0.001) scores were significantly improved. Patients with tunnel changes had decreased clinical and functional results at 6 months post-op of an iMPFLR (p < 0.001). These changes in the femoral tunnel, evidenced by a tunnel entrance widening and migration of the tunnel center, were related to an initial malposition of the tunnel (p < 0.001).

CONCLUSION

In iMPFLR, changes in the femoral tunnel, corresponding to dilatation and migration of the tunnel center, may occur. These changes are increased by the initial malpositioning of the femoral tunnel and are correlated with less good clinical and functional outcomes.

LEVEL OF EVIDENCE

Level IV.

Accelerated rehabilitation program following medial patellofemoral ligament reconstruction does not increase risk of recurrent instability

BACKGROUND

Rehabilitation protocols following medial patellofemoral ligament (MPFL) reconstruction were historically restrictive, with patients often immobilized and/or given weightbearing restrictions. However, more recently published protocols have been more aggressive. We compared patient-reported outcomes and recurrent dislocation risk between patients treated with a restrictive rehabilitation program (early post-operative bracing and weightbearing restrictions) and an accelerated rehabilitation protocol (no post-operative bracing or weightbearing restrictions) following MPFL reconstruction.

METHODS

Patients who underwent isolated MPFL reconstruction at an academic center between 2008 and 2016 were identified. Patient demographics, anatomical measurements, surgical details, and outcomes were collected. During this period, the rehabilitation protocol at the center transitioned from a restrictive to an accelerated rehabilitation protocol. Failure risk and patient-reported outcomes were compared based on rehabilitation protocol.

RESULTS

Of the163 isolated MPFL reconstructions performed during the study period, 123 (75%) were available for minimum one-year follow up at a mean of 4.0 years post-operative. Overall, 53 knees (43%) underwent the accelerated rehabilitation protocol and the remaining 70 knees (57%) underwent the restrictive protocol. There were 3 recurrent dislocations during the study period (2.4%), all of which occurred in the restrictive rehabilitation group. Multiple linear regression demonstrated that being in the accelerated rehabilitation group was not associated with poorer Knee injury and Osteoarthritis Outcome Score (KOOS) subscales controlling for age, sex, body mass index, Caton-Deschamps Index, tibial tubercle-trochlear groove distance, sulcus angle, MPFL graft choice, and length of follow-up.

CONCLUSION

An accelerated rehabilitation protocol without immobilization or weightbearing restrictions does not increase risk of recurrent patellar dislocation or poorer patient-reported outcome following isolated MPFL reconstruction.

Plantaris tendon is valuable graft for the medial patellofemoral ligament reconstruction: A biomechanical study

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a standard treatment option for selected patients with patellar instability. Although frequently performed, the optimal graft source for the procedure has not yet been established. This study aimed to determine whether a two-strand plantaris tendon construct possesses the biomechanical properties needed to act as an MPFL reconstruction graft.

METHODS

Thirty paired plantaris and gracilis tendons were harvested from 15 cadavers, mean age at death of 42.7 years. All specimens were frozen and maintained at -20 °C until biomechanical testing. Prior to mechanical testing, specimens were thawed at room temperature. The two-strand plantaris tendon and two-strand gracilis tendon constructs were created and secured in a uniaxial tensile testing machine in a triangular-shaped mode. Biomechanical properties for tensile testing to failure were determined using validated method. Results obtained were compared with the previously published data on native MPFL biomechanical properties.

RESULTS

The mean maximal force was 220.3 ± 108.1 N and 448.1 ± 117 N for the two-strand plantaris tendon construct and two-strand gracilis tendon construct, respectively. Significant differences were observed between all biomechanical properties of two-strand plantaris tendon and two-strand gracilis tendon constructs. The mean maximal force of a two-strand plantaris tendon construct and a two-strand gracilis tendon construct were greater than the mean maximal force of the native MPFL reported in all previous studies.

CONCLUSIONS

This study suggests that, due to its biomechanical properties, the two-strand plantaris tendon graft is suitable as a graft for MPFL reconstruction.

A Comprehensive Description of the Lateral Patellofemoral Complex: Anatomy and Anisometry

BACKGROUND

The lateral patellofemoral complex (LPFC) is an important stabilizer of the patella composed of the lateral retinacular structures including the lateral patellofemoral ligament (LPFL), the lateral patellomeniscal ligament (LPML), and the lateral patellotibial ligament (LPTL). While the isolated anatomy of the LPFL has been previously described, no previous study has investigated the entirety of the LPFC structure, length changes, and radiographic landmarks. An understanding of LPFC anatomy is important in the setting of LPFL injury or previous lateral release resulting in iatrogenic medial instability requiring LPFC reconstruction.

PURPOSE

To both qualitatively and quantitatively describe the anatomy and length changes of the LPFC on gross anatomic dissections and standard radiographic views.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired cadaveric specimens were utilized in this study. Specimens were dissected to identify distinct attachments of the LPFL, LPML, and LPTL. Ligament lengths, footprints, and centers of each attachment were described with respect to osseous landmarks using a 3-dimensional coordinate measuring device. Ligament length changes were also assessed from 0° to 90° of flexion. Radiopaque markers were subsequently utilized to describe attachments on standard anteroposterior and lateral radiographic views.

RESULTS

The individual elements of the LPFC were identified in all specimens. The LPFL patellar attachment had an average total length of 22.5 mm (range, 18.3-27.5 mm), involving a mean of 59% (range, 50%-75%) of the sagittal patella. Based on the average patellar size, a mean of 63% of the LPFL attached to the patella, and the remainder (11.1 ± 1.4 mm) inserted into the patellar tendon. The femoral attachment of the LPFL had a mean maximum length of 24.4 ± 4.3 mm. The center of the LPFL femoral attachment was a mean distance of 13.5 ± 3.2 mm anterior and distal to the lateral epicondyle. The LPFL demonstrated significant shortening, especially in the first 45° of flexion (7.5 ± 5.1 mm). In contrast, the LPTL (5.5 ± 3.0 mm) and LPML (10.0 ± 3.3 mm) demonstrated significant shortening from 45° to 90°. On lateral radiographs, the center of the femoral attachment of the LPFL was a mean total distance of 19.2 ± 7.2 mm from the lateral epicondyle.

CONCLUSION

The most important findings of this study were the correlative anatomy of 3 distinct lateral patellar ligaments (LPFL, LPML, and LPTL) and their anisometry through flexion. All 3 components demonstrated significant shortening during flexion. The quantitative and radiographic measurements detailed the LPFL osseous attachment on the patella; soft tissue attachment on the patellar tendon; and finally, the osseous insertion on the femur distal and anterior to the lateral epicondyle. Similarly, the authors documented the meniscal insertion of the LPML and defined a patellar insertion of the LPTL and LPML as a single attachment. These data allow for reproducible landmarks to aid in the understanding and reconstruction of the lateral patellar restraints.

CLINICAL RELEVANCE

The data produced from this investigation provide a comprehensive description of these 3 lateral patellar stabilizers (LPFL, LPML, LPTL). These data can be used intraoperatively to facilitate anatomic reconstructions of the lateral patellar stabilizers.

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 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.

CLINICAL RESULTS OF MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION

Objective

To assess clinical results of patients who underwent medial patellofemoral ligament (MPFL) reconstruction after a minimum of two years of follow-up.

Methods

Patients' medical records were assessed for residual instability, patient satisfaction, and post-operative functional outcomes.

Results

Fifty-one patients were analyzed, out of which 56.87% were women. Patients' mean age was 30.8 years (16 to 57 years). The mean follow-up time was 68.7 months (37 to 120 months). Length between first dislocation and surgery was less than 1 year for 58.82% of patients, between 1 and 5 years for 37.25%, and over 5 years for 3.93%. Patients showed a high degree of satisfaction (96.08% would undergo surgery again), with recurrence rate of 11.76%. Twenty-two patients reported knee symptoms, including pain from movements (72.72%), weakness (18.18%), constant pain (13.63%), and crepitus (4.54%). Considering dissatisfied patients, patients with dislocation recurrence, and patients with symptoms, five cannot practice physical activity, out of which only three blame their knee.

Conclusion

MPFL reconstruction showed a recurrence rate of 11.7%, with high patient satisfaction, good functional results, and high rate of return to sports, after a minimum of two years of follow-up. Level of Evidence IV, Case Series.

Complicações funcionais do tratamento da instabilidade patelar com reconstrução do ligamento femoropatelar medial com terço medial do tendão patelar com acompanhamento mínimo de 5 anos

Objetivo Avaliar complicações maiores após um mínimo de 5 anos de acompanhamento após luxação aguda ou recidivante da patela tratada com reconstrução do ligamento femoropatelar medial (LFPM) com terço medial do tendão patelar, com ou sem medialização da tuberosidade anterior da tíbia (TAT) associada.

Métodos Um total de 50 pacientes foram incluídos, com acompanhamento mínimo de 5 anos. Os pacientes foram avaliados em relação à ocorrência de complicações como rigidez articular, recidiva de luxação patelar ou instabilidade subjetiva relatada pelos pacientes, e incapacidade de retorno ao nível prévio de atividades físicas.

Resultados O acompanhamento médio foi de 8,9 ± 2,6 anos, com mínimo de 6 e máximo de 15 anos; 64% dos pacientes eram mulheres, com média de idade de 27 ± 11,2 anos; 24% dos pacientes foram submetidos a osteotomia da TAT para medialização concomitantemente; e 46% eram casos agudos. Foram constatados apenas 9 maus resultados (18%), todos decorrentes de recidiva da luxação (12%) e de queixa de instabilidade subjetiva (6%), ocorridos entre 36 e 60 meses de acompanhamento. Não ocorreram outras complicações. Dentre os maus resultados, cinco ocorreram em casos de luxação aguda, e quatro em casos recidivantes, e apenas um havia sido submetido a osteotomia da TAT.

Conclusão A reconstrução do LFPM com terço medial do tendão patelar, associada ou não à osteotomia de medialização da TAT, é uma alternativa no tratamento da instabilidade patelar aguda ou crônica, com falha de apenas 18% em acompanhamento mínimo de 5 anos. Além disso, é um tratamento seguro, sem apresentar outras complicações.

Tibial Tubercle Osteotomy May Not Provide Additional Benefit in Treating Patellar Dislocation With Increased Tibial Tuberosity-Trochlear Groove Distance: A Systematic Review

PURPOSE

To examine the indications and outcomes of medial patellofemoral ligament reconstruction (MPFLR) with or without tibial tubercle osteotomy (TTO) in treating recurrent or habitual patellar dislocation with an increased tibial tuberosity-trochlear groove (TT-TG) distance.

METHODS

We performed a literature search of the established medical databases Cochrane Central, PubMed-MEDLINE, EMBASE, and Web of Science. The inclusion criteria were as follows: skeletally mature patients with recurrent or habitual patellar dislocation and an increased TT-TG distance, treatment with MPFLR combined with a TTO procedure or isolated MPFLR, and reporting of clinical outcomes and complications. Each study was assessed for quality and the level of evidence. The general characteristics, indications, surgical techniques, TT-TG distance, clinical results, imaging evaluation findings, and complications of each study were recorded.

RESULTS

Nine studies consisting of 288 knees met the inclusion criteria. The average Coleman score was 71.56 (range, 55-83). The threshold for an increased TT-TG distance ranged from 16 to 20 mm in the included studies. Similar good postoperative outcomes were reported in patients with an increased TT-TG distance treated with MPFLR with versus without a TTO procedure. The mean postoperative Lysholm score ranged from 75.0 to 94.7 (I² = 87.6%) in the isolated MPFLR group and from 85.0 to 87.6 (I² = 16.3%) in the TTO-with-MPFLR group. Similar postoperative congruence angles were reported in both groups. The postoperative redislocation rate ranged from 0% to 4.2% in the TTO-with-MPFLR group, and no redislocation was found in the isolated MPFLR group. The postoperative apprehension sign was only reported in isolated MPFLR patients.

CONCLUSIONS

The outcomes of MPFLR with or without TTO to treat recurrent or habitual patellar dislocation with an increased TT-TG distance appeared similar. However, this study was limited by the considerable heterogeneity, variety of techniques, variety of TT-TG distances, and variability in patella alta and trochlear dysplasia among the included studies.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to IV studies.

Good results are reported at 60-month follow-up after medial patello-femoral ligament reconstruction with fascia lata allograft for recurrent patellar dislocation

PURPOSE

The aim of this study was to evaluate the efficacy of a new minimally invasive surgical technique for the reconstruction of the medial patellofemoral ligament (MPFL) with fascia lata allograft at 60-month minimum follow-up.

METHODS

Nineteen consecutive patients with chronic recurrent patellar dislocation were treated with MPFL reconstruction (53% isolate procedure, 47% in combination with other treatments). Seventeen patients (11 males/6 females) were available at 60-month follow-up and were clinically evaluated with validated scores. New episodes of patellar dislocation were considered failures. Radiographic and CT scan evaluation were executed preoperatively and at 60-month follow-up.

RESULTS

All clinical scores improved from preoperative assessment to 24-month and 60-month follow-up (p < 0.001). Kujala score increased from 61.2 ± 18.1 to 86.7 ± 8.7 and 82.1 ± 10.2; KOOS increased from 54.5 ± 19 to 86.8 ± 9.6 and 84.3 ± 7.6; VAS for pain decreased from 5.1 ± 2.2 to 2.4 ± 1.5 and 1.7 ± 1.2; Tegner score increased from 3 [2-4] to 5 [3-8] and 5 [3-9], respectively. Objective IKDC improved too. No significant improvements between the 24-month and 60-month follow-up evaluations were recorded. Anterior knee pain was reported in two patients (12%). Treatment failure, a new episode of patellar dislocation 25 months after the surgery, was observed in one patient (6%). Radiographic OA changes were not statistically significant between preop and 60-month follow-up. Tuberosity-troclear groove (TT-TG) distance and the patellar tilt angle were subjected to significant changes due to MPFL reconstruction and associated procedures.

CONCLUSION

MPFL reconstruction with fascia lata allograft, alone or combined with other procedures, is a reliable treatment option for recurrent patellar dislocation with a success rate of 94% and without cartilage deterioration at 60-month follow-up.

LEVEL OF EVIDENCE

IV.

Isolated MPTL reconstruction fails to restore lateral patellar stability when compared to MPFL reconstruction

PURPOSE

To biomechanically evaluate MPTL reconstruction and compare it with two techniques for MPFL reconstruction in regard to changes in patellofemoral contact pressures and restoration of patellar stability.

METHODS

This is an experimental laboratory study in eight human cadaveric knees. None had patellofemoral cartilage lesions or trochlear dysplasia as evaluated by conventional radiographs and MRI examinations. The specimens were secured in a testing apparatus, and the quadriceps was tensioned in line with the femoral shaft. Contact pressures were measured using the TekScan sensor at 30°, 60° and 90°. The sensor was placed in the patellofemoral joint through a proximal approach between femoral shaft and quadriceps tendon to not violate the medial and lateral patellofemoral complex. TekScan data were analysed to determine mean contact pressures on the medial and lateral patellar facets. Patellar lateral displacement was evaluated with the knee positioned at 30° of flexion and 9 N of quadriceps load, then a lateral force of 22 N was applied. The same protocol was used for each condition: native, medial patellofemoral complex lesion, medial patellofemoral ligament reconstruction (MPFL-R) using gracilis tendon, MPFL-R using quadriceps tendon transfer, and medial patellotibial ligament reconstruction (MPTL-R) using patellar tendon transfer.

RESULTS

No statistical differences were found for mean and peak contact pressures, medial or lateral, among all three techniques. However, while both techniques of MPFL-R were able to restore the medial restraint, MPTL-R failed to restore resistance to lateral patellar translation to the native state (mean lateralization of the patella [mm]: native: 9.4; lesion: 22; gracilis MPFL-R: 8.1; quadriceps MPFL-R: 11.3; MPTL-R: 23.4 (p < 0.001).

CONCLUSION

MPTL-R and both techniques for MPFL-R did not increase patellofemoral contact pressures; however, MPTL-R failed to provide a sufficient restraint against lateral patellar translation lateral translation in 30° of flexion. It, therefore, cannot be recommended as an isolated procedure for the treatment of patellar instability.

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.

Anatomy and biomechanics of the medial patellotibial ligament: A systematic review

BACKGROUND

The knowledge of the anatomy and biomechanics of patellar stabilizers is mandatory to achieve good clinical results with surgical reconstructive procedures. Few articles provide clear anatomical and biomechanical picture of medial patello-tibial ligament (MPTL).

METHODS

After a systematic review of the literature we selected in vivo or ex vivo studies providing anatomical or biomechanical measurements. We included 7 studies about MPTL anatomy for a total of 96 knees and 4 biomechanical studies.

RESULTS

The MPTL is a true ligament and important component of the medial patellar stabilizers, together with the medial patello-femoral ligament (MPFL) and medial patello-meniscal ligament. The contribution of MPTL on restriction forces of the patello-femoral joint is still unclear. Quadriceps, patellar, semitendinous and gracilis tendons are adequate grafts for surgical MPTL reconstruction.

CONCLUSIONS

MPTL is a well defined anathomical structure and histologically can be considered a ligament. It plays an important role in patellar stability especially it has a main role on patellar rotation and tilt instead on shift.

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.

Combined medial patellofemoral and patellotibial reconstruction with soft tissue fixation in recurrent patellar dislocation

INTRODUCTION

The medial patellofemoral and patellotibial ligaments (MPFL and MPTL) are the main passive restraints to lateral patellar translation. When nonoperative management of patellofemoral dislocations fails, surgical options can be considered to restore patellofemoral stability. Several reconstruction procedures of the MPFL with semitendinosus, gracilis, quadriceps tendon, and synthetic grafts have been described. No clear superiority of one surgical technique over another is evident.

MATERIALS AND METHODS

Patients who suffered at least two documented episodes of unilateral patellar dislocation, confirmed radiographically and at clinical examination, underwent combined MPFL and MPTL reconstruction. Patients were regularly followed-up postoperatively at 2, 4, 8, 12, and 24 weeks, and then annually for a minimum of 2.5 years. Clinical and functional evaluations were performed using the modified Cincinnati rating system and the Kujala score, while anthropometry values including thigh volume and cross-sectional area of the thigh were measured before the operation and at the latest follow-up bilaterally.

RESULTS

There were 7 males and 27 females with a mean age of 26.5 ± 10.7 years (range, 13-39 years). The mean follow-up was 3.1 years (range, 2.5-4 years). The mean modified Cincinnati score Increased from 51 ± 22 preoperatively to 90 ± 19 (P = .001). The mean Kujala scores increased from 47 ± 17 preoperatively to 82 ± 17 (P = .02), with no significant differences between patients with or without osteochondral lesions (P ≥ .05), and between male and female patients (P ≥ .08). The Insall-Salvati index was 1.1 preoperatively and remained within normal range (P = .05) at the latest follow-up.

CONCLUSION

Combined reconstruction of MPFL and MPTL using an ipsilateral autologous gracilis tendon is satisfactory and effective and can be considered as suitable management option to treat recurrent dislocation of the patella. However, randomized studies are needed to compare different techniques.

STUDY DESIGN

Case series.

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.

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.

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.

Clinical and Radiological Predictors of Functional Outcome After Isolated Medial Patellofemoral Ligament Reconstruction at Midterm Follow-up

BACKGROUND

Isolated medial patellofemoral ligament reconstruction (iMPFLR) is increasingly used for the surgical treatment of recurrent patellofemoral instability.

PURPOSE

The purpose of this study was to identify the clinical and radiological predictors that can significantly influence the functional outcomes after an iMPFLR.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 107 patients (112 ligament reconstructions) who underwent iMPFLR were evaluated with a mean ± SD follow-up of 59 ± 33 months (range, 12-123 months). Functional International Knee Documentation Committee (IKDC) and Kujala scores were assessed preoperatively and every 12 months. Radiological assessment of patellar height and tilt (Laurin angle, Merchant angle, Maldague classification) and computed tomography (CT) scan measurement of patellar tilt (contracted and relaxed quadriceps) and tibial tubercle-trochlear groove distance were performed preoperatively and at 6 months. Femoral tunnel position was assessed following the criteria formulated by Schöttle. The amount of femoral tunnel widening was measured by means of 3-dimensional CT scan at 6 months. Predictors were determined from univariate and multivariate regression analyses integrating clinical and radiological criteria pre- and postoperatively. The dependent variable was defined as the difference between pre- and postoperative scores.

RESULTS

Between pre- and postoperative measurement at last follow-up, a significant improvement for IKDC and Kujala functional scores was observed (Kujala: 57 ± 11.3 to 87 ± 12.9, P < .001; IKDC: 47.8 ± 13.1 to 79 ± 15.8, P < .001). Demographics (age, body mass index, sex), dislocation characteristics (number of dislocations, time between first dislocation and surgery, age at first dislocation, mechanism of first dislocation, knee side), clinical data (frontal limb alignment, hyperlaxity, recurvatum, pre- and postoperative range of motion), and complications (quadriceps atrophy, complex regional pain syndrome) did not influence functional scores. The predictors of lower improvement in functional scores included small correction of the patellar tilt reported on the CT scan measurement, malpositioning of the femoral tunnel, and a widening of this tunnel near the medial cortex. Malpositioning of the femoral tunnel was correlated with tunnel widening, and patients with anterior and proximal malpositioning experienced stiffness in flexion.

CONCLUSION

Overall, iMPFLR demonstrated good outcomes. Predictors influencing the functional results were identified. Less improvement in clinical outcome was reported for patients with a high preoperative patellar tilt and only a small correction in tilt and for those who had femoral tunnel malpositioning, which was correlated with tunnel widening.

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.

High heterogeneity in in vivo instrumented-assisted patellofemoral joint stress testing: a systematic review

PURPOSE

Summarize the in vivo instrumented-assisted patellofemoral evaluation methods for quantifying the patellar mobility in response to a known external force.

METHODS

A systematic review using PubMed, EMBASE, Cochrane Library, and SPORTDiscus electronic databases was conducted to search for studies reporting in vivo instrumented-assisted patellofemoral evaluation of patellar mobility. Searches were conducted in duplicate up to October 2017. Methodologic quality of included articles was assessed using a modified version of the Critical Appraisal Skills Program (CASP) critical appraisal tool.

RESULTS

From the original 2614 records, 9 studies comprising 568 individuals (24 ± 4.8 years old, 51.4% females)-355 (62.5%) asymptomatic individuals, 87 (15.3%) patellofemoral pain, and 126 (22.2%) patellofemoral instability patients-were included. The average maximum force applied by the instruments to the patella was 38.9 ± 27.7 N (range 11.25 to 80 N). Patellar displacement ranged from 3.9 to 10.4 mm, medially, and 3.5 to 14.8 mm, laterally, for asymptomatic individuals. For patellofemoral instability patients, these values were higher, ranging from 3.8 to 22.1 mm, medially, and 7.0 to 21.9 mm, laterally, being these mean values similar across the instability subgroups (medial, lateral, or multidirectional). Patellofemoral pain had a mean of 10 mm and 10.9 mm for medial and lateral displacements, respectively. Mean methodological quality score was 9.8 ± 2.6 (range 6-13) out of 18 possible points.

CONCLUSIONS

There is high heterogeneity within the available instrumented assessment methods and respective measurement outcomes, highlighting the need for better methodological standardization and further developments in this field. This would allow a more accurate and reliable quantification of patellar movement and, subsequently, improve diagnosis, and refine treatment.

LEVEL OF EVIDENCE

Systematic review of level II-IV studies, Level IV.

Medial patellofemoral ligament reconstruction with or without tibial tubercle transfer is an effective treatment for patellofemoral instability

PURPOSE

The hypotheses were that medial patellofemoral ligament reconstruction (MPFLr) would improve the long-term symptoms of patellofemoral Instability (PFI) and control patellar tilt, based on computed tomography (CT), and that the addition of a TT transfer, when it is necessary, would not deteriorate the outcome. The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of a large series of MPFLr, either isolated or associated with a TT transfer.

METHODS

From 133 MPFLr with a minimum of 4 years postoperatively, three groups were defined: isolated MPFLr, MPFLr with tibial tubercle (TT) medialisation or MPFLr with TT medialisation and distalisation. IKDC and Kujala scores were evaluated. Patellar tilt was evaluated on the patient's preoperative and the last available radiograph, and on CT scan measurements performed preoperatively and at 6-month postoperatively.

RESULTS

The mean follow-up was 6.3 ± 1.7 years [4.1-10.3] and four patients reported recurrent patellar dislocation. Between pre and postoperative at last follow-up a significant improvement in IKDC and Kujala functional scores was observed (P < 0.01), with no difference between the three groups. Regarding patellar tilt, there were significant decreases in Laurin and Merchant angles and an improvement of the Maldague stage (P < 0.01). The CT analysis of patellar tilt also demonstrates a significant improvement of the patella tilt (P < 0.01). The control of the patella tilt was correlated with a good functional result (P < 0.01).

CONCLUSION

The MPFLr, whether isolated or associated with a TT transfer, provides good long-term clinical and radiological outcomes with a low rate of recurrence. The addition of a TT transfer, when necessary, results in the same good outcomes. This article provides a guide for surgeons evaluating PFI to choose the most appropriate procedure.

LEVEL OF EVIDENCE

IV.

Combined reconstruction of the medial patellofemoral and medial patellotibial ligaments: outcomes and prognostic factors

PURPOSE

To report outcomes after combined medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) reconstruction and test associations between prognostic factors and clinical outcomes. It was hypothesised that combined MPFL and MPTL reconstruction would result in significant improvement in function, and that outcomes would be associated with age, sex, Beighton score, concomitant articular lesions, and preoperative function.

METHODS

All combined reconstructions of MPFL and MPTL were reviewed. Inclusion criterion was minimum 2-year follow-up. Exclusion criteria were age at surgery ≥ 35 years and concomitant osteotomies. Kujala, Tegner and Marx scores were completed prospectively. Patients were evaluated at a minimum 2-year follow-up. Associations between potential prognostic factors and Kujala and Tegner scores were tested using bivariate analyses followed by multivariate regression models.

RESULTS

Of 22 patients (26 knees), 19 (23 knees) met inclusion criteria, and 16 (20 knees) were available for follow-up. Mean age at surgery was 18 years (range 14.5-23). Mean follow-up was 43 months (range 24-73). Postoperative Kujala score significantly improved compared to before surgery (86.4 ± 12.5 vs. 54.9 ± 15.2, p < 0.01). Postoperative Tegner score was nonsignificantly higher compared to before surgery (4.8 ± 2.4 vs. 4 ± 3, p = ns) and lower compared to before first patella dislocation (4.8 ± 2.4 vs. 5.9 ± 1.2, p < 0.01). Postoperative Kujala score was associated with male sex (p = 0.02), with medial patellofemoral chondral lesions (p = 0.01) and with preoperative Kujala score (p = 0.05). Postoperative Tegner score was associated with male sex (p < 0.01), with preoperative Tegner level (p < 0.01), and with Beighton score (p < 0.01). Patella apprehension was recorded in two knees (10%) in two patients.

CONCLUSION

Combined MPFL and MPTL reconstruction in young adults results in significant improvement in subjective knee function with minimal risks, although preinjury activity levels are not consistently restored. Associated factors of improved outcome include higher preoperative knee scores and activity levels, medial patellofemoral chondral lesions, decreased Beighton scores, and male sex. This supports the advisability of the procedure and can also assist in setting realistic goals for specific groups of patients.

LEVEL OF EVIDENCE

Case series, Level IV.

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.

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.

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.

My Kind of Town (Chicago Is): Content Collections Optimize Learning Related to the 2018 AANA Annual Meeting

The 2018 Arthroscopy Association of North America Annual Meeting represents an opportunity to deepen one's understanding of a wide variety of topics. Arthroscopy journal readers have diverse practices and interests, and the meeting is designed to accommodate individual needs. The constructivist learning theory provides that scholars learn in many different ways. Thus, to enrich your learning experience, selected recently published Arthroscopy articles are suggested to supplement material presented at the meeting. The articles are collated on our web site in Content Collections, to allow meeting participants to prepare and to allow those unable to attend to remain engaged. We offer suggestions and encourage readers to customize their own learning experience.

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.

Editorial Commentary: The Medial Patellar Ligaments: A Step Closer to the Knee Surgeon's "Rubik's Cube" Solution

Recent cadaveric research analyzing the medial patellar ligaments and their contribution to patellar stability points out not only the need for reconstruction of the medial patellofemoral ligament, but also the medial tibiofemoral ligament to restore normal patellar stability and biomechanics.