Medial patellofemoral ligament reconstruction for patellar instability in patients with hypermobility: a case control study

The relationship between joint hypermobility and patellar instability: A systematic review

Introduction

Hypermobility describes the movement of joints beyond normal limits. Whether hypermobility predisposes to patellar instability is yet to be established. We aimed to determine if joint hypermobility leads to an increased risk of patellar instability, and to evaluate outcomes of treatment for patellar instability in those who exhibit hypermobility.

Methods

Published and unpublished literature databases were searched to September 7, 2023. Studies comparing prevalence of patellar dislocation/differences in treatment outcomes in patients with and without hypermobility were included.

Results

We identified 18 eligible studies (4,391 patients). The evidence was low in quality. A case series on 82 patients found that there was a relationship between generalised joint laxity and patellar instability. This was corroborated by a study comparing 104 patients with patellar dislocation to 110 patients without. Prevalence of generalised joint laxity was six time higher in the former (64.4% vs 10.9%, p < 0.001).Five studies found surgical intervention aimed at correcting patellar dislocation in patients with idiopathic hypermobility led to satisfactory outcomes. There was conflicting evidence regarding if hypermobile patients have worse outcomes than non-hypermobile patients following medial patellofemoral ligament reconstruction (MPFLR) in two studies. In addition, this procedure had a 19.1% failure rate in patients with Ehlers Danlos Syndrome (EDS), with hypermobility associated with a higher failure rate (p = 0.03). One study showed the type of graft used made no difference in outcome scores or re-dislocation rates (p > 0.5). Another study had 7/31 (22.6%) autografts which failed, compared to 2/16 allografts (12.5%) (p = 0.69).

Conclusion

Joint hypermobility is a risk factor for patellar instability. Identification of at-risk groups may aid prevention of dislocations and allow for appropriate treatment. Patients with EDS experience poor outcomes following patellar stabilization surgery, with post-operative monitoring required.

Functional benefit of joint surgery in patients with non-vascular Ehlers-Danlos syndrome: results of a retrospective study

BACKGROUND

Ehlers-Danlos syndrome (EDS) is a hereditary disease characterised by joint hypermobility, skin hyperextensibility and tissue fragility. Hypermobile EDS (hEDS is the more frequent subtype. Joint surgery may benefit certain patients after failure of medical treatments, but there is no consensus on the optimal surgical management of patients with hEDS. The aims of this retrospective study were to chart the surgical management of patients with hEDS, to determine the role of arthroscopy and to evaluate the functional results of joint surgery, including the reintervention rates.

RESULTS

A total of 69 patients with non-vascular EDS were evaluated (60 female; 87%). Mean (SD) age at first surgery was 25.6 ± 11.1 years. Among the 69 patients, first surgeries were carried out on the knee (n = 50; 39.4%), ankle (n = 28; 22.0%), shoulder (n = 22; 17.3%), wrist (n = 18; 14.2%) and elbow (n = 9; 7.1%). One-fifth of all first operations (20.8%) were carried out by arthroscopy, most often on the knee (36% of knee surgery cases). At the time of primary surgery, the surgeon was alerted to the diagnosis or suspicion of hEDS in only 33.9% of patients. The rate of reoperations (2 to ≥ 5) was 35.7% (10/28) for the ankle, 40.9% (9/22) for the shoulder, 44.4% (4/9) for the elbow, 50% (9/18) for the wrist and 60% (30/50) for the knee. Local or regional anaesthesia was badly tolerated or ineffective in 27.8%, 36.4% and 66.6% of operations on the wrist, shoulder and elbow, respectively. Overall, the majority of patients (> 70%) were satisfied or very satisfied with their surgery, particularly on the non-dominant side. The lowest satisfaction rate was for shoulder surgery on the dominant side (58.3% dissatisfied).

CONCLUSIONS

Surgery for joint instability has a greater chance of success when it is carried out in patients with a known diagnosis of EDS before surgery. The majority of patients were satisfied with their surgery and, with the exception of the knee, there was a low rate of reoperations (≤ 50%). Arthroscopic procedures have an important role to play in these patients, particularly when surgery is performed on the knee.

Midterm Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome

Background

Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown.

Purpose

To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes.

Study Design

Case series; Level of evidence, 4.

Methods

In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed.

Results

The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts (P = .69). For autografts, 6 of 17 (35.3%) failures occurred with gracilis, but 0 of 13 (0%) occurred with semitendinosus (P = .02). Compared with patients without failures, patients with failed primary MPFLR were significantly younger (P = .0005) and were able to touch the palm to the floor with their knees extended (P = .03). For radiographic parameters, the patellar height and tilt were significantly higher in the failure group. The postoperative PROs were suboptimal at a mean follow-up of 5.2 years. All but 1 patient were satisfied with the final outcome.

Conclusion

At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.

Double-Bundle Quadriceps Tendon Autograft for Reconstruction of the Medial Patellofemoral Complex to Manage Recurrent Patellar Dislocation in Patients With Open Physes

Management of chronic patellar instability in patients with open physis requires special reconstruction techniques to minimize the risks of femoral growth plate injury due to the close proximity of the open physis to the native femoral origin of the medial patellofemoral ligament (MPFL). Children and adolescents have a relatively smaller patella than the adult group, so, there is a higher risk of patellar fracture when tunnels are performed in the patella. It is wise to mimic the normal anatomy of the medial patellofemoral complex (MPFC) by reconstruction of both of the medial quadriceps tendon femoral ligament (MQTFL) and MPFL, so as to restore the normal fan-shaped MPFC, with its wide anterior attachment to both of the patella and quadriceps tendon (QT). This article describes a simple, safe, reproducible, and cost effective technique for surgical management of chronic patellar instability in patients with open physis by reconstruction of the MPFC using a double-bundle QT autograft.

Does Ligamentous Laxity Protect Against Chondral and Osteochondral Injuries in Patients With Patellofemoral Instability?

Background:

Many patients undergoing medial patellofemoral ligament (MPFL) reconstruction for patellofemoral instability have chondral or osteochondral injuries requiring treatment.

Hypothesis:

In patients undergoing MPFL reconstruction for patellofemoral instability, those with ligamentous laxity (LAX) would be less likely to have chondral or osteochondral defects requiring surgical intervention compared with those with no laxity (NLX).

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Included were 171 patients with patellofemoral instability (32 men, 139 women; mean age, 22 years [range, 11-57 years]) who underwent MPFL reconstruction between 2005 and 2015. Patients with a Beighton-Horan score ≥5 were considered LAX (n = 96), while patients with scores <5 were considered NLX (n = 75). Preoperative magnetic resonance images were evaluated to determine the presence, size, and location of chondral or osteochondral injury as well as the grade according to the Outerbridge classification. Documented anatomic measurements included tibial tubercle–trochlear groove (TT-TG) distance, Caton-Deschamps Index (CDI) for patellar height, and the Dejour classification for trochlear dysplasia.

Results:

Of the 171 patients, 58 (34%) required a surgical intervention for a chondral or osteochondral defect: chondroplasty (29/58; 50%), particulated juvenile cartilage implantation (18/58; 31%), microfracture (16/58; 28%), osteochondral fracture fixation (2/58; 3.4%), and osteochondral allograft (2/58; 3.4%). While there was no statistical difference in the proportion of patellar chondral or osteochondral injuries between patients with NLX (58%) versus LAX (67%) (P = .271), there was a significantly higher rate of patellar grade 3 or 4 injuries in the NLX (74%) versus LAX (45%) group (P = .004). Similarly, there was no difference in femoral chondral or osteochondral injury rates between groups (P = .132); however, femoral grade 3 or 4 injuries were significantly higher in the NLX (67%) versus the LAX (13%) group (P = .050). After adjusting for age, sex, radiographic parameters (TT-TG distance and CDI), and trochlear morphology, patients with LAX were 75% less likely to have had a grade 3 or 4 patellar cartilage injury compared with patients with NLX (P = .006).

Conclusion:

For patients who sustained patellar or femoral chondral or osteochondral injuries, compared with their counterparts with NLX, patients with LAX were less likely to have severe (grade 3 or 4) injuries requiring surgical intervention.

Putting it all Together: Evaluating Patellar Instability Risk Factors and Revisiting the "Menu"

Management of the patient with multiple risk factors for recurrent patellar instability is complex. Surgeons must possess familiarity with the anatomic risk factors that are associated with first time and recurrent instability events and weigh them in the patient's individualized surgical "menu" options for surgical patellar stabilization. Addressing individual risk factors, pairing imaging findings with physical examination, and thoughts on prioritizing risk factors to determine which should be prioritized for surgical correction are discussed.

Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy

STUDY DESIGN

Case-control.

OBJECTIVE

To examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT.

BACKGROUND

PT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT.

METHODS

11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests.

RESULTS

Patients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (-21.1° ± 5.9° vs. -14.8° ± 5.5°, P = .023) and step down (-15.6° ± 5.5° vs. -9.0° ± 6.0°, P = .017).

CONCLUSIONS

Patients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.

Clinical assessment of generalized ligamentous laxity using a single test: is thumb-to-forearm apposition enough?

The complete Beighton criteria, commonly used to establish the diagnosis of generalized ligamentous laxity (GLL), include nine discrete examination maneuvers. However, busy examiners may perform only a single maneuver (e.g. passive apposition of the thumb to the forearm) as a rapid method of assessment. We hypothesize that the use of a single-joint hypermobility test does not reliably identify the presence of GLL. Healthy patients 2-18 years old presenting to a general pediatric orthopaedic clinic were screened for participation. Exclusion criteria included the presence of a systemic illness, neuromuscular disease, and inability to complete the examination. Subjects were assessed for GLL according to the Beighton criteria, using a cutoff score of 5. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio were calculated for the thumb-to-forearm apposition test with the composite Beighton score used as the gold standard. Two hundred and four patients were included in the study, 111 females and 93 males, with an average age of 10.7 years. The prevalence of GLL was 13.3%. When thumb-to-forearm apposition was performed unilaterally, the PPV was poor (34%). Conversely, the NPV was excellent (99%). Sensitivity of thumb-to-forearm motion was extremely high (99%), although the specificity of this test was modest (67%). The likelihood ratio was fair (+3.3). Performing the test bilaterally did not significantly change its utility. Thumb-to-forearm apposition testing was equally effective in identifying the presence of GLL in males and females. When performed in isolation, assessment of thumb-to-forearm apposition has a poor PPV, excellent NPV, and modest likelihood ratio. It is an extremely sensitive test, with only fair specificity. Other upper extremity tests of GLL perform similarly. Therefore, while single tests like thumb-to-forearm apposition may be helpful for 'ruling out' GLL, they are less reliable at identifying it correctly. When single tests are used to identify GLL in either clinical or research settings, the results should be interpreted with caution. Level of evidence Level I (diagnostic).

Surgical Management of Shoulder and Knee Instability in Patients with Ehlers-Danlos Syndrome: Joint Hypermobility Syndrome

Ehlers-Danlos Syndrome (EDS) is a hereditary disorder of the connective tissue, which has been classified into numerous subtypes over the years. EDS is generally characterized by hyperextensible skin, hypermobile joints, and tissue fragility. According to the 2017 International Classification of EDS, 13 subtypes of EDS have been recognized. The majority of genes involved in EDS are either collagen-encoding genes or genes encoding collagen-modifying enzymes. Orthopedic surgeons most commonly encounter patients with the hypermobile type EDS (hEDS), who present with signs and symptoms of hypermobility and/or instability in one or more joints. Patients with joint hypermobility syndrome (JHS) might also present with similar symptomatology. This article will focus on the surgical management of patients with knee or shoulder abnormalities related to hEDS/JHS.

Treatment of patellar dislocation with arthroscopic medial patellofemoral ligament reconstruction using gracilis tendon autograft and modified double-patellar tunnel technique: minimum 5-year patient-reported outcomes

BACKGROUND

The purpose of this study was to retrospectively analyze the clinical outcomes of patients with recurrent patellar dislocation who underwent arthroscopic medial patellofemoral ligament (MPFL) reconstruction using gracilis tendon autograft and a modified double-patellar tunnel method. We hypothesized that our modified method would provide good clinical outcomes.

METHODS

Patients who underwent arthroscopic MPFL reconstruction with autograft gracilis tendon and modified double-patellar tunnels technique for recurrent patellar dislocation and were followed up for a minimum of 5 years were identified, and the clinical and follow-up data were retrospectively analyzed. Preoperatively, joint hypermobility was assessed with the Beighton score. The Insall-Salvati ratio, TT-TG distance, and Q angle were measured on radiographic images. Patient-reported outcomes including the Kujala, Lysholm, and Tegner scores were collected preoperatively and postoperatively. Patient satisfaction was assessed at the end of 5 years. Complications and recurrent dislocation occurring after surgery were recorded.

RESULTS

A total of 79 patients (94 knees) were enrolled; of these, 13 (16.5%) were lost to follow-up. The data of 66 patients (80 knees) were available for final analysis. Mean age at surgery was 21.3 ± 7.8 years. Mean follow-up time was 66.1 ± 5.5 months (range, 60-78 months). Postoperative patient-reported outcome was not associated with Beighton score, Insall-Salvati ratio, or TT-TG distance. Q angle was negatively correlated to Kujala scores and Lysholm scores. Severity of trochlear dysplasia was not associated with postoperative patient-reported outcome. The mean Kujala score increased from 69.4 ± 7.9 to 96.1 ± 1.9, the mean Tegner score increased from 3.1 ± 1.3 to 5.9 ± 1.3, and the mean Lysholm score increased from 73.5 ± 14.6 to 95.3 ± 3.4. Two patients experienced recurrent patellar dislocation during follow-up.

CONCLUSIONS

MPFL reconstruction using autologous gracilis tendon under arthroscopy appears to be a reliable and safe method for treating recurrent patellar dislocation.

LEVEL OF EVIDENCE

Level IV.

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.

Generalized joint hypermobility does not influence clinical outcomes following isolated MPFL reconstruction for patellofemoral instability

PURPOSE

Generalized joint hypermobility (GJH) has frequently been described as a risk factor for patellofemoral instability; however, only a few primary research studies have demonstrated any evidence of a relationship. The primary purpose of this study was to determine if isolated proximal soft tissue stabilization for patellofemoral instability is as successful in patients with GJH compared those without, as measured by disease-specific quality-of-life (QOL), symptom scores and functional outcomes. The secondary purpose was to determine if clinical and patient-reported outcomes were influenced by patient demographic factors in the presence of joint hypermobility.

METHODS

Between 2009 and 2014, data were collected on 174/193 knees (92% follow-up) following an isolated medial patellofemoral ligament reconstruction (MPFL-R). Patients with a Beighton score of 4 or greater were classified as positive for GJH, and any score of 3 or less was classified as negative. Pre- and post-operative Banff Patella Instability Instrument (BPII) scores were compared using a two-sample t test to determine the influence of GJH on QOL. The relationship between the Beighton score, and demographic and clinical factors was explored using correlational analysis. Functional testing including balance and single-leg hop testing was conducted 1 and 2 years post-operatively. Limb symmetry and mean limb-to-limb performance differences were calculated.

RESULTS

In this cohort of isolated MPFL reconstructions, 55.1% had a positive Beighton score. There were seven surgical failures (3.6%). There was no evidence of a relationship between a positive Beighton score and pre-operative BPII scores, post-operative BPII scores or post-operative symptom scores. GJH did not correlate significantly with any post-operative functional testing measures. A positive Beighton score was inversely related to patient age and more prevalent in females.

CONCLUSIONS

This study determined that the presence of GJH did not influence disease-specific quality of life, physical symptom score or functional outcomes following MPFL reconstruction.

LEVEL OF EVIDENCE

III.

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

BACKGROUND

Multiple studies have demonstrated that a number of demographic and pathoanatomic characteristics are associated with patellofemoral instability, recurrence of instability, and less satisfactory results following medial patellofemoral ligament reconstruction (MPFL-R). Despite the growing volume of research, the relationship of risk factors to patient-reported outcome after MPFL-R is unclear.

PURPOSE

To determine if certain pathoanatomic and demographic factors predict disease-specific quality-of-life outcome after isolated MPFL-R for symptomatic patellofemoral instability.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study analyzed 224 isolated MPFL-Rs. Demographic data were collected, including age at first dislocation, sex, and presence of bilateral instability. Pathoanatomic risk factors included the presence of high-grade trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, patella alta ratio, Beighton score, and patellar tilt. Other factors included femoral tunnel position accuracy and WARPS/STAID score. Descriptive analyses were conducted, followed by calculation of individual Spearman rank correlation coefficients for the predictor variables versus the Banff Patellofemoral Instability Instrument (BPII) scores. A multivariable regression with stepwise selection was employed to establish the final model predicting BPII score, with all significant variables for alpha ≤ .05 included in the final model.

RESULTS

The cohort of 224 patients included 66 (29.5%) males and 158 (70.5%) females, with a mean age of 24.1 years and a mean body mass index of 23.9 kg/m². The mean age of first patellar dislocation was 15.7 years, and 41.4% of patients had bilateral instability. Pathoanatomic variables within the cohort included the following: high-grade trochlear dysplasia = 41%; mean TT-TG = 14.6 mm, with 16.8% of patients demonstrating a TT-TG ≥18 mm; mean Caton-Deschamps ratio = 1.09, with 22% of patients demonstrating a ratio ≥1.2; and positive Beighton score = 37.5%. The mean BPII score at postoperative 2 years was 67.1 out of 100. A stepwise elimination in the regression model demonstrated no statistically significant 3- or 2-way relationships. Assessment of individual variables indicated that bilateral symptoms (P = .004), higher age at first dislocation (P = .024), and femoral tunnel position >10 mm from the Schöttle point (P = .042) were statistically significant predictors of lower quality-of-life scores. The R² value for the regression analysis model was 0.07.

CONCLUSION

In this large cohort of patients undergoing isolated MPFL-R for symptomatic lateral patellofemoral instability, a multivariable forward stepwise regression demonstrated that bilateral symptoms, femoral tunnel position, and age at first dislocation were statistically significant predictors of lower postoperative BPII scores. No anatomic risk factors were predictive of quality-of-life outcome score 2 years after MPFL-R surgery. The R² value indicated that there were many other important contributing factors affecting BPII outcome scores than those explored in this study.

Upsloping lateral sourcil: a radiographic finding of hip instability

While radiographic findings of frank hip dysplasia are well defined, there is a lack of diagnostic criteria for patients with radiographically ‘normal’ hips who have borderline morphologic deficits and clinical instability. In this study, we aim to define and validate a new radiographic finding associated with hip instability known as the upsloping lateral sourcil (ULS). Patients (316) were reviewed for lateral center edge angles, generalized joint laxity assessed with the Beighton Hypermobility Score and the presence of the ULS. The ULS was defined as a caudal-to-cranial inclination of the middle-to-far lateral aspect of the acetabular sourcil with loss of the normal lateral acetabular concavity. The prevalence of the ULS correspondingly increased with the degree of under-coverage as defined by LCEA. Within the normal coverage group, hips with a ULS had smaller LCEAs than those without ULS (29° versus 32°, P < 0.001). Among hips with a ULS, 59.00% had generalized joint laxity. The association between the ULS finding and generalized joint laxity was statistically significant (P < 0.01). The ULS is seen with higher prevalence in patients with clinical hip laxity and radiographically decreasing LCEA and may serve as an adjunctive finding in patients presenting with hip pain and instability. The ULS may help to characterize patients with borderline hip dysplasia and laxity that fall outside conventional imaging criteria for dysplasia.

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.

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

PURPOSE

The purpose of this article is to review anatomical, biomechanical, and clinical data of the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML), as well as studies focusing on the medial patellofemoral ligament (MPFL) but with relevant data about the MPTL and MPML.

METHODS

A literature search of articles specifically addressing the MPTL and/or MPML was included along with studies focusing on the MPFL but with relevant data about the MPTL and MPML.

RESULTS

The medial patellar ligaments responsible for maintaining the stability of the patellofemoral (PF) joint include the MPFL, the MPTL, and the MPML. The MPFL is considered the primary restraint to lateral patellar translation, while the latter two are considered secondary restraints. There is robust literature on the anatomical, imaging, and biomechanical characteristics of the MPFL, and also the clinical outcome of its injury and surgical reconstruction; much less is known about the MPTL and MPML. Isolated MPFL reconstruction has good clinical and functional outcomes, with a low failure rate when defined as frank re-dislocation. Complications, including continued episodes of patellar apprehension and subluxation, remain present in most series. In addition, the current literature primarily includes a homogeneous population with few excessive anatomic dysplastic factors. There is lack of knowledge on the role of MPTL and MPML in (potentially) aiding patella stabilization and improving clinical outcomes. Understanding the role of the medial-sided patellar ligaments, in particular the role of the secondary stabilizers, in PF function and injury will aid in this goal.

CONCLUSION

MPTL and MPML have consistent basic science literature, as well as favorable clinical outcomes of surgical patellar stabilization with reconstruction of the MPTL. However, there is much heterogeneity among clinical case series and lack of comparative studies to allow clear indication for the role of isolated or combined surgical reconstruction in patellar stabilization. Therefore, this comprehensive review helps understand the current knowledge and the possible applications in the orthopedic clinical practice.

LEVEL OF EVIDENCE

V.

An evaluation of the effectiveness of medial patellofemoral ligament reconstruction using an anatomical tunnel site

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability has gained popularity, and anatomical and biomechanical studies have recently altered our operative techniques. The aim of this study was to report the clinical outcome of this new anatomical MPFL reconstructive technique and investigate whether correlating factors could be identified.

METHODS

Between 2009 and 2012, a total of 31 consecutive patients underwent MPFL reconstruction using an autologous gracilis graft and anatomical tunnel placement. Pre- and post-operative data were collected as a part of routine clinical practice. The preoperative assessment included a rotational profile CT scan of the lower extremity according to the Lyon protocol with TT-TG distance measurement. Outcomes were evaluated with the Kujala and Norwich patella instability (NPI) scores preoperatively and at follow-up (1.5-5.1 years).

RESULTS

A significant improvement in both the Kujala (p < 0.001) and NPI (p = 0.012) scores was recorded. A medium and large negative correlations were found between TT-TG distance and Kujala score improvement (ρ = -0.48, p = 0.020) and NPI score improvement (ρ = -0.83, p = 0.042), respectively. Multiple regression analysis identified TT-TG distance, Beighton score and BMI as factors explaining the variance of Kujala score improvement.

CONCLUSION

Anatomical MPFL reconstruction with the gracilis autograft for patellar instability resulted in good outcome. This underlines the importance of anatomical tunnel placement in MPFL reconstruction. With a precise preoperative work-up, factors can be identified that may guide selecting the optimal operative strategy and improve counselling of the patient.

LEVEL OF EVIDENCE

Case series, Level IV.

Medial patellofemoral ligament reconstruction: patient selection and perspectives

Patellofemoral instability is a painful and often recurring disorder with many negative long-term consequences. After a period of failed nonoperative management, surgical intervention has been used to reduce the incidence of patellar subluxation and dislocations. Medial patellofemoral ligament (MPFL) reconstruction successfully addresses patellofemoral instability by restoring the deficient primary medial patellar soft tissue restraint. When planning MPFL reconstruction for instability, it is imperative to consider the patient's unique anatomy including the tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, and patella alta. Additionally, it is important to individualize surgical treatment in the skeletally immature, hypermobile, and athletic populations.

Evaluation of a modified knee rotation angle in MRI scans with and without trochlear dysplasia: a parameter independent of knee size and trochlear morphology

PURPOSE

Regarding TT-TG in knee realignment surgery, two aspects have to be considered: first, there might be flaws in using absolute values for TT-TG, ignoring the knee size of the individual. Second, in high-grade trochlear dysplasia with a dome-shaped trochlea, measurement of TT-TG has proven to lack precision and reliability. The purpose of this examination was to establish a knee rotation angle, independent of the size of the individual knee and unaffected by a dysplastic trochlea.

METHODS

A total of 114 consecutive MRI scans of knee joints were analysed by two observers, retrospectively. Of these, 59 were obtained from patients with trochlear dysplasia, and another 55 were obtained from patients presenting with a different pathology of the knee joint. Trochlear dysplasia was classified into low grade and high grade. TT-TG was measured according to the method described by Schoettle et al. In addition, a modified knee rotation angle was assessed. Interobserver reliability of the knee rotation angle and its correlation with TT-TG was calculated.

RESULTS

The knee rotation angle showed good correlation with TT-TG in the readings of observer 1 and observer 2. Interobserver correlation of the parameter showed excellent values for the scans with normal trochlea, low-grade and high-grade trochlear dysplasia, respectively. All calculations were statistically significant (p < 0.05).

CONCLUSION

The knee rotation angle might meet the requirements for precise diagnostics in knee realignment surgery. Unlike TT-TG, this parameter seems not to be affected by a dysplastic trochlea. In addition, the dimensionless parameter is independent of the knee size of the individual.

LEVEL OF EVIDENCE

II.

Trochleoplasty with a flexible osteochondral flap: results from an 11-year series of 214 cases

AIMS

The Bereiter trochleoplasty has been used in our unit for 12 years to manage recurrent patellar instability in patients with severe trochlea dysplasia. The aim of this study was to document the outcome of a large consecutive cohort of patients who have undergone this operation.

PATIENTS AND METHODS

Between June 2002 and August 2013, 214 consecutive trochleoplasties were carried out in 185 patients. There were 133 women and 52 men with a mean age of 21.3 years (14 to 38). All patients were offered yearly clinical and radiological follow-up. They completed the following patient reported outcome scores (PROMs): International Knee Documentation Committee subjective scale, the Kujala score, the Western Ontario and McMaster Universities Arthritis Index score and the short-form (SF)-12.

RESULTS

Outcomes were available for 199 trochleoplasties in 173 patients giving a 93% follow-up rate at a mean of 4.43 years (1 to 12). There were no infections or deep vein thromboses. In total, 16 patients reported further patella dislocation, giving an 8.3% rate of recurrence. There were 27 re-operations, giving a rate of re-operation of 14%. Overall, 88% were satisfied with the operation and 90% felt that their symptoms had been improved.

CONCLUSION

All PROMs improved significantly post-operatively except for the mental component score of the SF-12. Trochleoplasty performed using a flexible osteochondral flap is an effective treatment for recurrent patellar instability in patients with severe trochlea dysplasia and gives good results in the medium term. Cite this article: Bone Joint J 2017;99-B:344-50.

Adolescent patellar instability

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis.

Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis.

This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients.

Cite this article: Bone Joint J 2017;99-B:159–70.

Complications of medial patellofemoral ligament reconstruction using two transverse patellar tunnels

PURPOSE

The aim of this study was to report the complication rate after a medial patellofemoral ligament (MPFL) reconstruction using transverse patellar tunnels in a retrospective case series performed in a single institution.

METHODS

Case series of 179 patients (192 knees) that had an MPFL reconstruction, with or without additional bony realignment procedures, between January 2009 and March 2015. Data were obtained from available patient charts.

RESULTS

Thirty-nine complications (20.3 %) were registered. Twenty-seven of these (14.7 %) were minor. Seven patients (3.6 %) sustained a patellar fracture without adequate trauma. Male gender was a risk factor for patellar fracture (p < 0.001). Sixteen (8.1 %) reported recurrence of instability, of whom 10 (5.1 %) were defined as objective instability (reported dislocation and positive apprehension test).

CONCLUSION

This is largest patient series to date in which the complications after a two tunnel MPFL reconstruction are described. The use of transverse patellar tunnels increases the risk of sustaining a patellar fracture.

LEVEL OF EVIDENCE

IV.

Modified Broström Procedure for Chronic Lateral Ankle Instability in Patients With Generalized Joint Laxity

BACKGROUND

Generalized joint laxity (GJL) has been considered a risk factor for late failure of ligament reconstruction in the knee; however, it is not known whether GJL is the cause of recurrent instability after the modified Broström procedure for chronic lateral ankle instability.

PURPOSE

To compare the clinical results of the modified Broström procedure for chronic lateral ankle instability in patients with or without GJL.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 100 patients (100 ankles) who underwent the modified Broström procedure were divided into 2 groups, with or without GJL, according to the Beighton criteria. Age and body mass index were matched between the 2 groups. The mean follow-up duration was 43.3 months in the laxity group (44 ankles; Beighton score ≥5) and 42.9 months in the nonlaxity group (56 ankles).

RESULTS

The mean preoperative Karlsson and American Orthopaedic Foot and Ankle Society (AOFAS) scores were a respective 53.2 and 60.9 in the laxity group and 53.9 and 62.6 in the nonlaxity group, and these scores improved to 87.4 and 89.5, respectively, in the laxity group and to 94.1 and 94.8, respectively, in the nonlaxity group at final follow-up. The mean preoperative talar tilt angle and anterior talar translation were a respective 12.5° and 8.8 mm in the laxity group and 10.8° and 8.5 mm in the nonlaxity group, and these values improved to 7.3° and 6.0 mm, respectively, in the laxity group and to 5.2° and 5.0 mm, respectively, in the nonlaxity group at final follow-up. Failure rates were 11.4% (5 patients) in the laxity group and 1.8% (1 patient) in the nonlaxity group. Significant differences were found between the 2 groups in terms of the Karlsson score, AOFAS score, talar tilt angle, anterior talar translation, and failure rate at final follow-up (P < .05).

CONCLUSION

Patients with GJL showed inferior outcomes and a higher failure rate compared with patients without GJL. Therefore, GJL appears to be a risk factor associated with recurrent instability after the modified Broström procedure.

Anatomic physeal-sparing technique for medial patellofemoral ligament reconstruction in skeletally immature patients with ligamentous laxity

PURPOSE

To evaluate the clinical outcome of this modified physeal-sparing technique for MPFL reconstruction in skeletally immature patients with ligament laxity.

PATIENTS AND METHODS

This study was conducted on 16 patients (11 females and 5 males) with an average age of 11.5 years (8-15). They all had recurrent patellar dislocation with generalized ligament laxity (mean Beighton's score of 7) and no patellar tilt on X-ray. We modified the Frank Noyes' non-anatomic technique for MPFL reconstruction to become anatomic without hardware fixation for the graft.

RESULTS

The mean follow-up period was 29.25 months (SD 4.3) ranged from 24 to 34 months. Preoperative Kujala score had ranged from 49 to 61 points (mean of 56, SD 4.72), improved to be ranged from 90 to 99 points (mean 94, SD 2.73), which is considered highly significant (p value < 0.005). Till the latest follow-up, there were no definite re-dislocation episodes in any of our patients.

CONCLUSION

The described technique allows reconstruction of the MPFL in skeletally immature patients with ligament laxity avoiding any potential risks of growth disturbances or chondral damage as compared to other techniques. The modification of two-point femoral fixation allows both a more anatomic and more secure form of reconstruction and is cost-effective without the need for hardware.

Measurement of tibial tuberosity-trochlear groove distance: evaluation of inter- and intraobserver correlation dependent on the severity of trochlear dysplasia

PURPOSE

Excessive tibial tuberosity-trochlear groove distance (TT-TG) is considered as one of the major risk factors in patellofemoral instability (PFI). TT-TG characterises the lateralisation of the tibial tuberosity and the medialisation of the trochlear groove in the case of trochlear dysplasia. The aim of this study was to assess the inter- and intraobserver reliability of the measurement of TT-TG dependent on the grade of trochlear dysplasia.

METHODS

Magnetic resonance imaging (MRI) scans of 99 consecutive knee joints were analysed retrospectively. Hereof, 61 knee joints presented with a history of PFI and 38 had no symptoms of PFI. After synopsis of the axial MRI scans with true lateral radiographs of the knee, the 61 knees presenting with PFI were assessed in terms of trochlear dysplasia. The knees were distributed according to the four-type classification system described by Dejour.

RESULTS

Regarding interobserver correlation for the measurements of TT-TG in trochlear dysplasia, we found r=0.89 (type A), r=0.90 (type B), r=0.74 (type C) and 0.62 (type D) for Pearson's correlation coefficient. Regarding intraobserver correlation, we calculated r=0.89 (type A), r=0.91 (type B), r=0.77 (type C) and r=0.71 (type D), respectively. Pearson's correlation coefficient for the measurement of TT-TG in normal knees resulted in r=0.87 for interobserver correlation and r=0.90 for intraobserver correlation.

CONCLUSION

Decreasing inter- and intraobserver correlation for the measurement of TT-TG with increasing severity of trochlear dysplasia was detected. In our opinion, the measurement of TT-TG is of significance in low-grade trochlear dysplasia. The final decision to perform a distal realignment procedure based on a pathological TT-TG in the presence of high-grade trochlear dysplasia should be reassessed properly.

LEVEL OF EVIDENCE

Retrospective study, Level II.