Cartilage viability after trochleoplasty

Bony Procedures for surgical patellar stabilization

Surgery for patellofemoral instability is usually 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 due to the presence of several risk factors. Risk factors include demographics such as age, contralateral dislocation, as well as anatomic risk factors (ARF) such as abnormal coronal and rotational alignment, trochlear dysplasia, lateral quadriceps vector, and patella alta. Surgery with soft tissue procedures includes restoring the medial patellar restraints and balancing the lateral side of the joint and can be successful in most patients. However, patients that have excessive and/or several ARF have a high risk of failure with isolated soft tissue stabilization procedures; associated surgical correction of select ARFs is recommended. This article will discuss an approach to evaluate the risk-benefit of adding bony procedures which may decrease the changes of recurrence of patellar instability but can increase surgery-related complications. Approaching patellofemoral instability in a patient-specific approach and combining corrective osteotomies and trochleoplasties with a shared decision with the patient/family, guiding surgeons to deliver optimal care for the patellar instability patient.

Evaluation of Patellar Dysplasia and Postoperative Pain After Mini-Open, Thin-Flap Trochleoplasty: A Retrospective Analysis of 75 Consecutive Cases

Background

The association between inherent patellar anatomy and postoperative pain after trochleoplasty in patients with patellar instability is poorly understood.

Purpose/Hypothesis

The study purpose was to evaluate outcomes after mini-open, thin-flap trochleoplasty. The hypothesis was that more severe patellar dysplasia would be correlated with increased postoperative pain after trochleoplasty.

Study Design

Case series; Level of evidence 4.

Methods

Patients with patellar instability who underwent mini-open, thin-flap trochleoplasty in combination with other individualized procedures between 2013 and 2022 were included. Patellar dysplasia was evaluated by calculating the Wiberg index at the widest and most distal cartilaginous parts of the patella on preoperative magnetic resonance imaging. At the postoperative follow-up, participants completed the visual analog scale for usual pain (VAS-U), Banff Patellofemoral Instability Instrument 2.0 (BPII), global rating of change scale, and an evaluation of their current symptom state. Redislocations and complications were recorded. The correlation between the Wiberg index and the VAS-U was calculated with the Spearman rho. Between-group analyses based on demographic and pathoanatomic features were conducted using the Mann-Whitney U test, independent-samples t test, and chi-square test.

Results

Included were 75 knees in 63 patients (median age at surgery, 19.1 years; IQR, 16-22 years) with a median follow-up of 44 months (IQR, 23.8-83.2 months). The median BPII score was 78.2 (IQR, 54.8-92.5), with 88% reporting an improvement in knee function relative to before surgery, but 21.1% remained dissatisfied with their current knee symptom state. New episodes of patellar dislocation were seen in 3 knees (4%), and 14 knees (18.7%) underwent reoperation with either revision surgery (n = 7; 9.3%) or arthroscopic synovectomy (n = 7; 9.3%). A weak positive, nonsignificant correlation was found between increased postoperative pain and a higher Wiberg index, both at the widest (r S = 0.16; P = .23) and most distal (r S = 0.02; P = .89) parts of the patella. Significantly worse VAS-U scores were seen in female versus male patients (P = .013).

Conclusion

Good patient-reported results with a low risk of redislocation were seen in the study cohort, but reoperation rates were high, and 21% of the patients remained dissatisfied with their current symptom state. More pronounced patellar dysplasia (increased Wiberg index) had only a poor association with more severe postoperative pain in the current study.

Good short-term results following arthroscopic deepening trochleoplasty combined with medial patellofemoral ligament reconstruction: surgical technique and outcomes

PURPOSE

To report short-term results and clinical outcomes of arthroscopic deepening trochleoplasty combined with medial patellofemoral ligament (MPFL) reconstruction utilizing standard arthroscopic instruments in patients of recurrent patellar dislocation and trochlear dysplasia.

METHODS

This is a case series of 13 patients between the ages of 14 and 20 years who presented with recurrent patellar dislocation and severe trochlear dysplasia (Dejour grade D). They were treated surgically using an arthroscopic technique from February 2017 to January 2019 and were followed for 18 months. Patients were assessed preoperatively and postoperatively (at 6, 12, and 18 months) with clinical scores (Tegner Activity Score, Lysholm Knee Score, and Kujala Score).

RESULTS

There were 69.2% females, and the mean age was 16.4 ​± ​2.0 years. There were statistically significant improvements in the mean Lysholm and Kujala scores when comparing pre-operative and post-operative scores at every follow-up landmark (p ​< ​0.05). Comparing the preoperative and 18-month postoperative scores-the Lysholm score improved from 68.2 ​± ​10.3 to 98.7 ​± ​2.1 (p ​< ​0.001), and the Kujala score improved from 50.3 ​± ​12.0 to 95.4 ​± ​4.8 (p ​< ​0.001). Five patients were able to achieve premorbid Tegner activity levels at 12 months, with an additional 5 patients achieving the same premorbid Tegner activity at the 18-month mark. The remaining 3 patients were able to attain >90% of their activity level at 18 months' follow-up. No complications were observed during the follow-up period.

CONCLUSIONS

This proposed arthroscopic deepening trochleoplasty technique combined with MPFL reconstruction has demonstrated excellent and reproducible early clinical outcomes.

LEVEL OF EVIDENCE

IV.

A modified Delphi consensus statement on patellar instability: part II

Aims

The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process.

Methods

This was the second part of a study dealing with these aspects of management in these patients. As in part I, a total of 60 surgeons from 11 countries contributed to the development of consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered unanimous.

Results

Of 41 questions and statements on patellar instability, none achieved unanimous consensus, 19 achieved strong consensus, 15 achieved consensus, and seven did not achieve consensus.

Conclusion

Most statements reached some degree of consensus, without any achieving unanimous consensus. There was no consensus on the use of anchors in MPFL reconstruction, and the order of fixation of the graft (patella first versus femur first). There was also no consensus on the indications for trochleoplasty or its effect on the viability of the cartilage after elevation of the osteochondral flap. There was also no consensus on postoperative immobilization or weightbearing, or whether paediatric patients should avoid an early return to sport.

Trochlear Shape and Patient-Reported Outcomes After Arthroscopic Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction: A Retrospective Cohort Study Including MRI Assessments of the Trochlear Groove

Background

Sparse objective data are available documenting changes of trochlear shape after trochleoplasty.

Purpose/Hypothesis

The purpose was to investigate whether standardized magnetic resonance imaging (MRI) measurements that characterize trochlear dysplasia (TD) change significantly after arthroscopic deepening trochleoplasty (ADT) combined with medial patellofemoral ligament (MPFL) reconstruction. It was hypothesized that MRI measurements would approximate normal values.

Study Design

Case series; Level of evidence, 4.

Methods

Patients who underwent ADT between October 2014 and December 2017 were considered for this study. The preoperative inclusion criteria for ADT surgery were patellar instability, a dynamic patellar apprehension sign at 45° of flexion, a lateral trochlear inclination (LTI) angle of <11°, and failed physical therapy. MRI was performed pre- and postoperatively, and standardized MRI measurements were calculated: LTI angle, trochlear depth, trochlear facet asymmetry, cartilage thickness, and trochlear height. The Banff Patella Instability Instrument 2.0 (BPII) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Kujala score were obtained pre- and postoperatively.

Results

A total of 16 knees in 15 patients (12 female and 3 male; median age, 20.9 years; range, 14.1-51.3 years) were evaluated. The mean follow-up time was 63.6 months (range, 23-97 months). The median LTI angle improved from 1.25° (range, -25.1° to 10.6°) preoperatively to 10.7° (range, -17.7° to 25.8°) postoperatively (P < .001), trochlear depth increased from 0.0 mm (range, -4.2 to 1.8 mm) to 3.23 mm (range, 0.25-5.3 mm) (P < .001), and trochlear facet asymmetry improved from 4.55% (range, 0.0%-28.6%) to 17.8% (range, 0.0%-55.6%) (P < .003). Cartilage thickness was unchanged: 4.5 mm (range, 1.9-7.4 mm) preoperatively and 4.9 mm (range, 0.6-8.3 mm) postoperatively (P = .796). BPII, KOOS, and Kujala scores improved significantly (P < .0034 for all).

Conclusion

Combined ADT and MPFL reconstruction led to statistically significant and clinically relevant improvements in patient-reported outcomes and standardized MRI measurements that characterize TD. The improvements corresponded to those obtained by open trochleoplasty. No significant reduction in cartilage thickness was seen.

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.

➤

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.

➤

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.

Grooveplasty Compared With Trochleoplasty for the Treatment of Trochlear Dysplasia in the Setting of Patellar Instability

Purpose

To compare the clinical efficacy in the resolution of patellar instability, patient-reported outcomes (PROs), and complication and reoperation rates between patients who underwent grooveplasty (proximal trochleoplasty) and patients who underwent trochleoplasty as part of a combined patellofemoral stabilization procedure.

Methods

A retrospective chart review was performed to identify a cohort of patients who underwent grooveplasty and a cohort who underwent trochleoplasty at the time of patellar stabilization. Complications, reoperations, and PRO scores (Tegner, Kujala, and International Knee Documentation Committee scores) were collected at final follow-up. The Kruskal-Wallis test and Fisher exact test were performed when appropriate, and P < .05 was considered significant.

Results

Overall, 17 grooveplasty patients (18 knees) and 15 trochleoplasty patients (15 knees) were included. Seventy-nine percent of patients were female, and the average follow-up period was 3.9 years. The mean age at first dislocation was 11.8 years overall; most patients (65%) had more than 10 lifetime instability events and 76% of patients underwent prior knee-stabilizing procedures. Trochlear dysplasia (Dejour classification) was similar between cohorts. Patients who underwent grooveplasty had a higher activity level (P = .007) and a higher degree of patellar facet chondromalacia (P = .008) at baseline. At final follow-up, no patients had recurrent symptomatic instability after grooveplasty compared with 5 patients in the trochleoplasty cohort (P = .013). There were no differences in postoperative International Knee Documentation Committee scores (P = .870), Kujala scores (P = .059), or Tegner scores (P = .052). Additionally, there were no differences in complication rates (17% in grooveplasty cohort vs 13% in trochleoplasty cohort, P > .999) or reoperation rates (22% vs 13%, P = .665).

Conclusions

Proximal trochlear reshaping and removal of the supratrochlear spur (grooveplasty) in patients with severe trochlear dysplasia may offer an alternative strategy to complete trochleoplasty for the treatment of trochlear dysplasia in complex cases of patellofemoral instability. Grooveplasty patients showed less recurrent instability and similar PROs and reoperation rates compared with trochleoplasty patients.

Level of Evidence

Level III, retrospective comparative study.

Good patient satisfaction with low complications rate after trochleoplasty in patellofemoral instability

PURPOSE

Trochlear dysplasia has been recognized as the most common factor in patients with patellofemoral dislocation. Trochleoplasty is a surgical procedure whose primary goal is to modify the femoral trochlea's abnormal shape in patients suffering from patellar instability, requiring good surgical skills, correct indication, and accurate patient information.

METHODS

The review aims to describe preoperative planning, patient selection, most common surgical techniques, and clinical results of trochleoplasty in patellar instability in a reproducible manner.

RESULTS

Trochleoplasty can be considered a general term to describe a group of different procedures that reduce trochlear dysplasia's impact on patellar instability, aiming to restore patella-trochlear congruency, remove the supratrochlear bump, allowed a new groove positioning and are generally associated with other procedures. Recent studies showed satisfactory long-term results with the restoration of patellar stability, improving radiological findings of patellofemoral instability.

CONCLUSION

Trochleoplasty is a technically demanding technique, requiring careful patient selection, detailed knowledge, and surgical skills to avoid severe complications. Good patient satisfaction with a low risk of significant complications such as patellofemoral arthritis has been revealed. In conclusion, trochleoplasty should be systematically included in the treatment of patellar dislocation, if indicated.

LEVEL OF EVIDENCE

V.

Trochlear Dysplasia: When and How to Correct

When? Only patients with high-grade trochlear dysplasia types B and D, in which the prominence of the trochlea (supratrochlear spur) is over 5 mm, recurrent patellar dislocation, and maltracking. How? Sulcus deepening trochleoplasty: modifies the trochlear shape with a central groove and oblique medial and lateral facets; decreases the patellofemoral joint reaction force by reducing the trochlear prominence (spur); and reduces the tibial tubercle and the trochlear groove value by a proximal realignment. Pros: This procedure is highly effective in restoring patellofemoral stability and satisfying the patients. Cons: The patients must be aware of the risk of continuing residual pain and range-ofmotion limitation and that the development of patellofemoral osteoarthritis is not predictable.

Current Concepts Regarding Patellofemoral Trochlear Dysplasia

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

Traumatic Patellar Dislocations in Childhood and Adolescents

Patellar instability and associated patellar dislocation can result in significant pain, disability, and associated injuries in young athletes. The patellofemoral joint is a complex articulation with stabilizing restraints, both medially and laterally, that help guide the patella into the corresponding trochlear groove as the knee cycles through an extension-to-flexion arc. In addition to soft tissue injuries, many osseous aberrancies can contribute to patellar instability in young athletes, including trochlear dysplasia, patella alta, and axial and coronal plane abnormalities. There is a role for nonoperative treatment in these young athletes; however, if recurrent or associated injuries are identified surgical intervention is warranted. Correct diagnosis of the underlying cause of the patellar instability is paramount to developing a surgical plan that will yield the most favorable outcome for these young athletes.

Trochleoplasty improves knee flexion angles and quadriceps function during gait only if performed bilaterally

PURPOSE

To investigate if a trochleoplasty increases knee flexion angles and extensor moments in the gait of patients with patellar instability and to compare postoperative gait to a healthy control group.

METHODS

A bilateral dislocation group (6 patients) and a unilateral dislocation group (14 patients) were treated with bilateral and unilateral trochleoplasty, respectively. Kinematics and kinetics of the lower extremity were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, plug-in-gait, two force plates). The mean of six trials was computed. The gait cycles were compared pre to postoperatively for each group. The gait of the two groups was compared to each other and the gait of a healthy population (54 knees).

RESULTS

After trochleoplasty, the knee flexion angles and knee extensor moments only increased in the bilateral dislocation group, whereas the gait pattern of the unilateral dislocation group remained unchanged. Compared to the healthy population, the postoperative gait pattern of the bilateral dislocation group did not differ. In contrast, knee flexion angles and extensor moments of the unilateral dislocation group were still lower.

CONCLUSION

In adolescents with bilateral recurrent patellar dislocations, trochleoplasty of both knees increases knee flexion angles and knee extensor moments comparable to normal gait. Unilateral symptomatic patients undergoing a unilateral trochleoplasty did not achieve normal walking. These findings point out that patellar instability should be considered as a bilateral problem, even in patients with unilateral dislocations.

LEVEL OF EVIDENCE

III.

[Diagnosis and therapy of chronic patellofemoral instability]

The chronic patellofemoral instability is a multifactorial disease, which is mostly congenital. Luxation of the patella is mainly atraumatic. Sole conservative treatment is often unsuccessful. Surgical treatment is needed in most cases and requires consideration of all pathologic changes of the patella-stabilizing anatomic structures. Rupture of the medial patellofemoral ligament is almost pathognomonic. In addition, the frontal mechanical axis, rotation of femur and tibia, the trochlear shape, the distance from the tibial tuberosity to the trochlear sulcus and the patellar height play an important role. Often, in addition to soft tissue reconstruction, the bony alignment needs to be corrected. Consideration of risk factors in both adult and adolescent patients is needed to avoid recurrent instability.

When is Trochleoplasty a Rational Addition?

Trochlear dysplasia has been recognized as a dominant anatomic risk factor in patients with recurrent patellar instability. Sulcus-deepening trochleoplasty is a very effective and powerful procedure for correcting trochlear dysplasia and, specifically, eliminating the supratrochlear spur. However, it must be emphasized that trochleoplasty is not appropriate for patients with mild trochlear dysplasia or those without a large supratrochlear spur or bump. We discuss the characteristics and classification of trochlear dysplasia and discuss specific indications for sulcusdeepening trochleoplasty.

Deepening trochleoplasty and medial patellofemoral ligament reconstruction normalize patellotrochlear congruence in severe trochlear dysplasia

AIMS

The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia.

PATIENTS AND METHODS

The study group comprised 20 patients (two male, 18 female; mean age 24 years (16 to 39)) who underwent deepening trochleoplasty and medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent lateral patellar dislocation due to severe trochlear dysplasia (Dejour type B to D). Pre- and postoperative MRI investigations of the study group were compared with MRI data of 20 age- and gender-matched control patients (two male, 18 female; mean age 27 years (18 to 44)) regarding the patellotrochlear contact ratio, patellotrochlear contact area, posterior patellar edge-trochlear groove ratio, and patellar tilt.

RESULTS

Preoperatively, all parameters in the study group indicated significant patellar malalignment, including a reduced patellotrochlear contact ratio (mean 0.38 (0.13 to 0.59) vs mean 0.67 (0.48 to 0.88); p < 0.001), reduced contact area (mean 128 mm² (87 to 190) vs mean 183 mm² (155 to 227); p < 0.001), increased patellar lateralization (mean 0.82 (0.55 to 1.0) vs mean 0.99 (0.93 to 1.1); p < 0.001) and increased patellar tilt (mean 25.8° (8.1° to 43.0°) vs mean 9.1° (0.5° to 16.8°); p < 0.001). Postoperatively, all parameters in the study group improved significantly and reached normal values compared with the control group. The patellotrochlear contact ratio increased to a mean of 0.63 (0.38 to 0.85) (p < 0.001), the contact area increased to a mean of 187 mm² (101 to 255) (p < 0.001), the posterior patellar edge-trochlear groove ratio improved to a mean of 0.96 (0.83 to 0.91) (p < 0.001), and the patellar tilt decreased to a mean of 13.9° (8.1° to 22.1°) (p < 0.001) postoperatively.

CONCLUSION

Deepening trochleoplasty and MPFL reconstruction normalized the patellotrochlear congruence and patellofemoral alignment parameters. Modifying the dysplastic trochlea involves approximating the trochlear morphology to the shape of the patella rather than inducing a patella and trochlea mismatch. Cite this article: Bone Joint J 2019;101-B:325-330.

A combined procedure with Bereiter-type trochleoplasty leads to a stable patellofemoral joint at 5-year follow-up

PURPOSE

Trochlear dysplasia is a major risk factor predisposing to patellar instability and has been reported to occur in up to 85% of patients with recurrent patellar dislocation. Different operative techniques have been described to correct trochlear dysplasia, including the Bereiter technique, in which subchondral bone is removed and the cartilage can be compressed into a U-shaped groove. The hypothesis was that after a Bereiter-type trochleoplasty combined with medialisation of the tibial tubercle and MPFL reconstruction, patellar pain and instability decreased and anatomic reconstruction can be seen radiographically after 5-year follow-up.

METHODS

Between 2004 and 2011, a combined procedure including Bereiter-type trochleoplasty was performed on 21 consecutively included patients (22 knees) with objective patellar instability and severe trochlear dysplasia. Instability and pain were assessed preoperatively and 3, 6, 12, 24 and 60 months postoperatively with the visual analogue scale (VAS) for pain and instability, Kujala, International Knee Documentation Committee Subjective Knee Evaluation (IKDC SKE) and Short Form Health Survey (SF-36). Pre- and postoperatively, a true lateral radiograph was made to investigate the presence of the crossing sign and to measure the trochlear bump and trochlear depth, as well as a sunrise patella view to measure the sulcus angle.

RESULTS

VAS pain and instability, Kujala and IKDC SKE improved significantly 5 years after trochleoplasty (p < 0.05). SF-36 showed no significant improvement. None of the patients reported patellar dislocations postoperatively. Sport activities remained limited. Postoperative radiographs showed no crossing sign. There was a significant increase in trochlear depth (p < 0.0001) and also a significant decrease in trochlear bump and sulcus angle (both p < 0.0001).

CONCLUSIONS

A combined procedure consisting of Bereiter-type trochleoplasty, medialisation of the tibial tubercle and MPFL reconstruction in patients with objective patellar instability and severe trochlear dysplasia resulted in a clear decrease of pain and instability. Radiological assessment showed anatomical reconstruction. Nevertheless, residual symptoms remain and the possibility of future cartilage damage is uncertain.

LEVEL OF EVIDENCE

IV.

Femoral Trochleoplasty for Recurrent Patellar Dislocation: Treating the Underlying Trochlear Dysplasia

The patellofemoral joint presents a complex biomechanical interaction involving soft tissues and bony structures to maintain joint stability. The most relevant factor is trochlear dysplasia which is present in 85% of patients. Femoral trochleoplasty is a surgical procedure to recreate the trochlear groove. This case report describes a young patient who had all clinical factors of patellar instability and trochlear dysplasia. Radiology studies showed trochlear dysplasia type C according to the Dejour classification. The patient underwent a trochleoplasty with an elevated flap of cartilage and subchondral bone as described by Ryzek and Schöttle [J Knee Surg 2015; 28(4): 297–302], associated with the reconstruction of the medial patellofemoral ligament. Femoral trochleoplasty is a surgical procedure to recreate the trochlear groove by removing subchondral bone to create a new trochlear sulcus, while respecting the kinematics and biomechanics of the patellofemoral joint.

Trochlear dysplasia: imaging and treatment options

Recurrent patellar dislocation is a disabling condition, which can lead to articular cartilage injuries, osteochondral fractures, recurrent instability, pain, decreased activity and patellofemoral osteoarthritis. Trochlear dysplasia represents an important component of patellar dislocation.

Imaging provides an objective basis for the morphological abnormalities and thus allows determination of the surgical strategy according to the concept of ‘à la carte’ surgery.

The main surgical techniques of trochleoplasty are the sulcus deepening trochleoplasty, the ‘Bereiter’ trochleoplasty and the recession trochleoplasty.

At mid-term, all techniques have shown a postoperative improvement in clinical scores, with a low rate of recurrence of dislocation and a possible return to sport. But these techniques do not halt the progression of patellofemoral arthritis.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170058

Validation of the German version of the Kujala score in patients with patellofemoral instability: a prospective multi-centre study

INTRODUCTION

The Kujala score is the most frequently used questionnaire for patellofemoral disorders like pain, instability or osteoarthritis. Unfortunately, we are not aware of a validated German version of the Kujala score. The aim of our study was the translation and linguistic validation of the Kujala score in German-speaking patients with patella instability and the assessment of its measurement characteristics.

MATERIALS AND METHODS

The German Kujala score was developed in several steps of translation. In addition to healthy controls, the Kujala German was assessed in consecutive patients undergoing reconstruction of the medial patellofemoral ligament for recurrent patellar dislocations. Pre-op, 6 and 12 months postop the patients completed the Kujala German score, the KOOS, the Lysholm score, a VAS Pain, and the SF-12v2 scores. In addition, there was a Kujala German Score retest preop after a 1-week interval.

RESULTS

We found high reliability in terms of internal consistency for the Kujala score (Cronbach's alpha = 0.87). Convergent validity with the KOOS (symptom r = 0.65, pain r = 0.78, ADL r = 0.74, sports/recreation r = 0.84, quality of life r = 0.70), the Lysholm score (r = 0.88) and the SF-12 physical component summary score (r = 0.79) and VAS pain (r = - 0.71) was also very high. Discriminant validity in terms of correlation with the SF-12 mental component summary Score was satisfactory (r = 0.14).

CONCLUSIONS

In conclusion, the German version of the Kujala score proved to be a reliable and valid instrument in the setting of a typical patellofemoral disease treated with a standard patellofemoral procedure.

Deepening trochleoplasty combined with balanced medial patellofemoral ligament reconstruction for an adequate graft tensioning

AIM

To evaluate our modified deepening trochleoplasty combined with a balanced medial patellofemoral ligament (MPFL) reconstruction for soft tissue alignement.

METHODS

Thirty-three knees with with recurrent patellar dislocations and a trochlear dysplasia in 30 patients (m/f = 12/21, mean age 24 ± 9 years) underwent a combination of a modified deepening trochleoplasty and a balanced MPFL reconstruction for a medial soft tissue alignement. After a mean follow-up period of 29 ± 23 mo, patients’ return to sports, possible complications as well as the clinical outcomes using the Kujala, International Knee Documentation Committee (IKDC) and Lysholm scoring were evaluated. Moreover, patients’ satisfaction with the general outcome, the cosmetic outcome, the pre- and postoperative pain and a potential avoidance behaviour were assessed with additional standardized questionnaires which also included different visual analog scales.

RESULTS

There were no signs of a persistent instability. The Kujala score improved from a mean of 64 ± 16 points to 94 ± 9 points, the Lysholm score improved from a mean of 63 ± 17 to 95 ± 6 points and the IKDC score from 58 ± 11 to 85 ± 12 points, P < 0.0001, respectively. The assessment of pain using a visual analog scale showed a significant pain reduction from a mean of 4.8 ± 2.0 to 1.3 ± 3.4 points (P < 0.0001). Two of 26 cases (92%) who were engaged in regular physical activity before surgery did not return to full sporting activities. One patient felt that his sport was too risky for his knee and reported an ongoing avoidance behaviour. The other patient preferred to wait for surgery of her contralateral knee. Of the eight patients who were not engaged in sporting activities before surgery, three started regular sporting activities after surgery. In 31 of the 33 cases (94%), the patients were very satisfied with the clinical outcome of the surgery. Regarding the cosmetic results, no patients felt impaired in their self-confidence and in their clothing decisions.

CONCLUSION

Our technique shows a good clinical outcome in terms of the common scorings as well as in terms of pain, return to sports and patient satisfaction.

The lateral wedge augmentation trochleoplasty in a pediatric population: a 5-year follow-up study

Patellofemoral instability in children requires surgery when recurrent dislocation occurs. The aim of this study is to report the 5-year clinical and radiographic outcomes following lateral wedge augmentation trochleoplasty of the femoral trochlea. This is a review of 23 (mean age: 12.5 years) patients who underwent surgery for recurrent patellar dislocations related to a flat trochlea. In every case, a lateral wedge augmentation trochleoplasty was performed with preservation of the growth plate. This surgery was consistently associated with a soft tissue procedure. All patients were reviewed for a clinical and radiographic evaluation [computed tomography (CT)-scan]. No case of recurrent patellar dislocation was reported and all patients were satisfied with the procedure; three patients reported anterior knee pain after physical activities. CT scan analysis revealed improvement of the trochlear shape measurements in all cases, but osteoarthritis lesions (narrowing of the lateral patellofemoral compartment) were visible on four CT scans. This trochleoplasty technique augmented by a soft tissue procedure on the extensor apparatus led to acceptable clinical mid-term results in terms of stability for patients with a flat trochlea (grade B according to Dejour classification). However, at the 5-year follow-up, four patients showed signs of osteoarthritis on CT scan evaluation. This warrants serious concern in this young population, and alternative methods should be considered whenever possible.

Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies

Patellar instability is a common clinical problem encountered by orthopedic surgeons specializing in the knee. For patients with chronic lateral patellar instability, the standard surgical approach is to stabilize the patella through a medial patellofemoral ligament (MPFL) reconstruction. Foreseeably, an increasing number of revision surgeries of the reconstructed MPFL will be seen in upcoming years. In this paper, the causes of failed MPFL reconstruction are analyzed: (1) incorrect surgical indication or inappropriate surgical technique/patient selection; (2) a technical error; and (3) an incorrect assessment of the concomitant risk factors for instability. An understanding of the anatomy and biomechanics of the MPFL and cautiousness with the imaging techniques while favoring clinical over radiological findings and the use of common sense to determine the adequate surgical technique for each particular case, are critical to minimizing MPFL surgery failure. Additionally, our approach to dealing with failure after primary MPFL reconstruction is also presented.

A new classification system of patellar instability and patellar maltracking

To date there is no classification of patellar dislocations considering clinical and radiological pathologies. As a result many studies mingle the dislocation's underlying pathologies, so that there are no consistent therapy recommendations. It is this article's objective to introduce a patellar dislocation classification based on the current literature to allow for the application of a structured diagnosis and treatment algorithm. The classification is based on instability criteria as well as on clinical and radiological analyses of maltracking and on loss of patellar tracking. There are five types of patellar instability and maltracking. The rare type 1 is a simple (traumatic) patellar dislocation without maltracking and instability with a low risk of redislocation. Type 2 has a high risk of redislocation after primary dislocation; there is no maltracking. Here, a stabilising operation (in most cases MPFL reconstruction) is indicated and sufficient. Type 3 shows both instability and maltracking. Maltracking is mainly caused by: (a) soft tissue contracture, (b) patella alta, (c) pathological tibial tuberosity-trochlea groove distance, (d) valgus deviations and (e) torsional deformities. Stabilisation by means of isolated MPFL reconstruction is not sufficient in these types and additional osseous corrective surgeries are required to achieve physiological patellar tracking and to prevent redislocation. Type 4 features a highly unstable "floating patella" with complete loss of tracking caused by severe trochlear dysplasia. Therapy of choice is trochleoplasty, and if necessary combined with bony and soft-tissue procedures. Type 5 shows a patellar maltracking without instability. Maltracking can only be fixed by means of corrective osteotomy. The classification is referenced to current literature and each type is introduced by a case example. The resulting treatment consequence is also presented.

An Algorithmic Approach to the Management of Recurrent Lateral Patellar Dislocation

High-level evidence supports nonoperative treatment for first-time lateral acute patellar dislocations. Surgical intervention is often indicated for recurrent dislocations. Recurrent instability is often multifactorial and can be the result of a combination of coronal limb malalignment, patella alta, malrotation secondary to internal femoral or external tibial torsion, a dysplastic trochlea, or disrupted and weakened medial soft tissue, including the medial patellofemoral ligament (MPFL) and the vastus medialis obliquus. MPFL reconstruction requires precise graft placement for restoration of anatomy and minimal graft tension. MPFL reconstruction is safe to perform in skeletally immature patients and in revision surgical settings. Distal realignment procedures should be implemented in recurrent instability associated with patella alta, increased tibial tubercle-trochlear groove distances, and lateral and distal patellar chondrosis. Groove-deepening trochleoplasty for Dejour type-B and type-D dysplasia or a lateral elevation or proximal recession trochleoplasty for Dejour type-C dysplasia may be a component of the treatment algorithm; however, clinical outcome data are lacking. In addition, trochleoplasty is technically challenging and has a risk of substantial complications.

Combined trochleoplasty and MPFL reconstruction for treatment of chronic patellofemoral instability: a prospective minimum 2-year follow-up study

PURPOSE

Excessive trochlear dysplasia may be responsible for recurrent patellofemoral instability (PFI) due to a missing bony guidance for the patella in early flexion. Thus, an isolated medial patellofemoral ligament reconstruction (MPFLR) can be insufficient, since it mainly addresses instability close to extension and additionally can increase patellofemoral pressure leading to pain in flat or convex trochlear dysplasia. Therefore, in combination with a trochleoplasty, an anatomical trochlear groove is created, resulting in patellofemoral stability also in flexion, while patellofemoral pressure is normalized. In this prospective study, we evaluated the outcome of open trochleoplasty in combination with MPFLR with a minimum follow-up of 2 years for treatment of excessive PFI.

METHODS

In between 2007 and 2009, 18 knees of 17 consecutive patients (mean age of 22.2 ± 4.9 years) with trochlear dysplasia type B, C or D according to Dejour et al. and positive apprehension from 0 to 60° of flexion were included. Tegner, Kujala and IKDC scores, apprehension and pain, trochlear dysplasia, sulcus angle, tibial tuberosity trochlear groove, patellar tilt and shift, Caton-Deschamps index as well as patellofemoral arthrosis according to the classification of Iwano et al. were assessed pre- and postoperatively.

RESULTS

At a mean of 30.5 ± 5.9 months, all but one patient were subjectively satisfied with the outcome of the procedure, all showing absence of positive apprehension or redislocation. Significant (p < 0.001) reduction in pain (5.6 to 2.5 ± 2.8 points, VAS) and increase in Tegner (2, range 0-4 points to 6, range 3-8 points), Kujala (51.1 to 87.9 ± 20.0 points) and IKDC (49.5 to 80.2 ± 21.0%) scores could be achieved. Radiologically significant (p < 0.02) improvement of patellofemoral positional parameters leading to more normal anatomy was recorded, while short-term arthrosis was absent.

CONCLUSIONS

Combined treatment for trochleoplasty with MPFLR serves as a successful therapy for chronic PFI. This combinatory treatment concept is a reliable option not only as salvage therapy but also as primary procedure regarding treatment for excessive PFI.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

Current concepts on trochleoplasty procedures for the surgical treatment of trochlear dysplasia

Trochleoplasty is a surgical procedure, whose goal is to change the abnormal shape of the femoral trochlea in patients with recurrent patellar dislocation. Such surgeries that aim to reshape the articular surface of a bone without damaging it are quite unique in orthopaedic surgery. Although in the beginning, trochleoplasty was reserved for the refractory cases where previous surgery has failed, the last years it became more and more popular because of a better knowledge of anatomy and biomechanics and a greater availability of instruments. The roots of the deepening trochleoplasty could be found in the previous century when the first surgeons tried to directly remove the dysplastic bone with pioneer interventions but with devastating consequences. Since then, multiple procedures have been described and are analysed in this review; each one with its unique features, advantages and pitfalls. Regardless of the technique used, the very recent bibliography presents very encouraging results from the application of trochleoplasty with other procedures in a selected population with severe trochlear dysplasia and recurrent patellar dislocation, in whom the benign neglect of dysplasia would lead to unfavourable results.

LEVEL OF EVIDENCE

IV.

Trochlear dysplasia and the role of trochleoplasty

The diagnosis and treatment of chronic patellar instability caused by trochlear dysplasia can be challenging. A dysplastic trochlea leads to biomechanical and kinematic changes that often require surgical correction when symptomatic. In the past, trochlear dysplasia was classified using the 4-part Dejour classification system. More recently, new classification systems have been proposed. Future studies are needed to investigate long-term outcomes after trochleoplasty.

Clinical and electromyographic results of proximal and distal realignment procedures in young patients with recurrent patellar dislocations

BACKGROUND

Until now, no study has been published about the electromyographic changes in the extensor apparatus after the Green procedure for proximal realignment in young patients with recurrent patellar dislocations. This electromyographic study was performed to analyze imbalances between the vastus medialis and vastus lateralis muscles after different patellar realignment procedures.

HYPOTHESIS

Surgical proximal realignment leads to electromyographic changes in the extensor apparatus of the knee and to imbalances between the vastus medialis and vastus lateralis muscles.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 28 knees of 25 patients, with a mean age of 15 years, were treated operatively for recurrent patellar dislocations. The mean follow-up was 6.3 years. Depending on the type of surgical intervention, the patients were assigned to 3 different groups: the patients of group 1 underwent only the Green vastus medialis obliquus (VMO) advancement, group 2 was treated with a combination of the Green proximal and the Roux-Goldthwait distal realignment, and group 3 was treated with a combination of the Green proximal realignment and an additional tubercle transfer. All patients underwent clinical, radiological, and electromyographic examinations. The muscle activities of a healthy control group without patellar dislocations were used for comparison.

RESULTS

A combination of the Green procedure and tubercle transfer led to significantly better clinical results and a lower number of redislocations (P < .05) compared with patients who underwent only the Green proximal realignment. While ascending or descending stairs, the ratio between the electromyographic activities of the vastus medialis and vastus lateralis muscles in groups 1 and 2 was significantly smaller compared with the control group (P < .02). Only the electromyograms of group 3 revealed a balanced extensor apparatus during loading with comparable activities of the vastus medialis and vastus lateralis muscles and no significant difference to the control group (P = .37).

CONCLUSION

Our electromyographic investigations showed the importance of the vastus medialis in the pathogenesis of malalignment of the extensor mechanism. The Green VMO advancement without tibial tubercle transfer is not able to balance the activities of the vastus medialis and vastus lateralis muscles and cannot be recommended for further use.

Midterm results of comprehensive surgical reconstruction including sulcus-deepening trochleoplasty in recurrent patellar dislocations with high-grade trochlear dysplasia

BACKGROUND

Trochlear dysplasia is one of the most consistent anatomic factors that can lead to recurrent patellar dislocations. Various trochleoplasty procedures have been described to treat patellar dislocations in high-grade dysplasia by creating a new congruent trochlea.

PURPOSE

To present the midterm efficacy and outcome of the sulcus-deepening trochleoplasty procedure in patients with recurrent patellar dislocations due to high-grade trochlear dysplasia. The clinical evaluation results, the amount of radiological correction, and the prevalence of arthritis were recorded.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 27 skeletally mature patients (31 knees) with recurrent patellar dislocations due to high-grade trochlear dysplasia without any previous surgery were retrospectively included from September 1993 to September 2006. All patients underwent sulcus-deepening trochleoplasty combined with a bony and/or soft tissue procedure according to concomitant etiological factors to patellar dislocations: medial patellofemoral ligament reconstruction (16.1%), vastus medialis obliquus plasty (83.8%), tibial tuberosity distalization (51.6%), tibial tuberosity medialization (67.7%), and lateral retinaculum release (67.6%). Mean follow-up was 7 years (range, 2-9 years).

RESULTS

The mean sulcus angle decreased significantly (P < .01) from 152° ± 16° preoperatively to 141° ± 9° postoperatively, tibial tuberosity-trochlear groove distance decreased significantly (P < .001) from 19 ± 4 mm to 12 ± 5 mm, and patellar tilt decreased significantly (P < .001) from 37° ± 7° to 15° ± 8°. No recurrence was observed, and there was no case of stiffness. Apprehension signs remained positive in 19.3% of the cases, patellar tracking was normal in all cases, and the lateral patellar glide test finding was negative in 96.8%. The mean preoperative International Knee Documentation Committee (IKDC) score was 51 (range, 25-80), and the mean postoperative IKDC score was 82 (range, 40-100) (P < .001), while the mean Kujala score improved from a preoperative 59 (range, 28-81) to 87 (range, 49-100) postoperatively (P < .001). There was no radiographic evidence of patellofemoral arthritis at the latest follow-up.

CONCLUSION

Sulcus-deepening trochleoplasty is a valid option for the primary surgical treatment of carefully selected patients with recurrent patellar dislocations with high-grade trochlear dysplasia type B and D. Concomitant etiological factors must be cautiously corrected in an associated procedure. Midterm follow-up showed satisfactory restoration of patellar stability and improvement of knee scores with no complication of subsequent arthritis.

The Lyon's sulcus-deepening trochleoplasty in previous unsuccessful patellofemoral surgery

PURPOSE

Trochleoplasty is a relatively rare operation with few published results and it remains a technically demanding procedure which requires careful patient selection. The ideal candidate for surgery remains to be elucidated, and some authors consider it as a good revision option in cases of previous unsuccessful operations for persisting patellar dislocation with underlying trochlear dysplasia. The purpose of this study is to record the results from the application of sulcus-deepening trochleoplasty in patients with trochlear dysplasia and previous unsuccessful surgery for patellar dislocation.

METHODS

Twenty-two patients (24 knees) were operated upon during the period 9/1993-9/2006; they had undergone surgery for patellofemoral instability and had persistent patellar dislocation, and were followed-up for a mean of 66 months (24-191). Trochleoplasty was performed in all patients using the same technique and rehabilitation protocol. Additional soft-tissue and bony operations were performed in every case.

RESULTS

Of all cases, 29.1% had type B and 70.9% had type D trochlear dysplasia. After trochleoplasty, no patient had a patellar re-dislocation up to the last follow-up. Pain decreased in 72% and the apprehension sign was negative in 75% of the cases (p < 0.01). Sulcus angle decreased from 153° ± 14° to 141° ± 10° (p < 0.01), TT-TG distance decreased from 16 ± 6 mm to 12 ± 2 mm (p < 0.001), and patellar tilt decreased from 31° ± 14° to 11° ± 8° (p < 0.0001). Mean pre-operative Kujala score was 44 (25-73) and at the latest follow-up it increased to 81 (53-100), (p < 0.001). At the time of final follow-up, there was no case of patellofemoral arthritis.

CONCLUSIONS

Trochlear dysplasia is a key factor in the treatment of recurrent patellar dislocation and its correction could be included in the surgical options. Sulcus-deepening trochleoplasty is an acceptable revision option for the surgical treatment of patients with persisting patellar dislocation and high-grade trochlear dysplasia.

The role of trochleoplasty in patellofemoral instability

The management of recurrent patellofemoral instability is challenging. The etiology of the instability is multifactorial, requiring the examination of lower limb alignment, relationship of the patella to the trochlear groove and tibial tubercle, and the soft-tissue restraints. As initial surgical efforts were aimed at isolated soft-tissue repair or reconstruction, patients often had continued instability. Thus, a heightened interest in trochleoplasty has occurred as trochlear dysplasia has been found in 85% of patients with recurrent instability. Different types of trochleoplasties have been developed depending on the type of dysplasia including the trochlear lengthening osteotomy, the proximal open trochleoplasty, the deepening trochleoplasty, and the arthroscopic deepening trochleoplasty. The techniques, benefits, and results of these trochleoplasties will be presented in this review.

Trochleoplasty in major trochlear dysplasia: current concepts

Trochleoplasty is the theoretical solution to persistent symptoms (pain and/or instability) related to trochlear dysplasia where there is not only a trochlear flatness but also a trochlear prominence. The threshold of prominence indicating surgical intervention has as yet not been determined. A bump of 5 mm is generally accepted as the inferior limit. Given the interventional nature of this demanding procedure, it should be proposed in selected cases after considerable discussion with the patient. Trochleoplasty is indicated as a primary procedure for major trochlear dysplasia with a prominence > 5 mm. Stabilization is obtained in most of the cases with the risk of residual mild anterior knee pain. It is also indicated as a salvage procedure when a previous surgery failed. Despite the reputation of the procedure, the published results are encouraging in terms of prevention of re-dislocation, satisfaction index, and radiological outcomes. Post-operative stiffness is the main complication, which may require manipulation under anaesthesia or arthroscopic arthrolysis. There are few other complications reported and to date secondary necrosis of the trochlea has not been reported. Technically speaking, the deepening trochleoplasty is a difficult procedure without reliable landmarks. We propose a recession wedge trochleoplasty which is an easier procedure. It is never undertaken as an isolated procedure, but always in conjunction with other realignment procedures of the extensor apparatus according to the "a la carte" surgery concept.

Recession wedge trochleoplasty as an additional procedure in the surgical treatment of patellar instability with major trochlear dysplasia: early results

INTRODUCTION

The importance of a dysplastic trochlea as a component of patellar instability has long been recognized. An original trochleoplasty technique consisting in retro-trochlear recession wedge osteotomy was described by Goutallier et al. The aim is not to fashion a groove but to reduce the bump without modifying patellofemoral congruence.

PATIENTS AND METHODS

This retrospective study reports the operative technique and short-term outcomes of a consecutive case series of 17 patients (19 knees) who underwent recession wedge trochleoplasty for patellofemoral instability associated with severe trochlear dysplasia. Other contributing factors of patellar instability were also corrected as part of the surgical procedure: tibial tuberosity transfer (n=18), MPFL reconstruction (n=8).

RESULTS

Minimum follow-up was 12 months (mean, 34 months; range, 12 to 71 months). The trochlear prominence was reduced from a mean 4.8mm (range, 0 to 8mm) to -0.8mm (range, -8 to 6mm). Patellar tilt was reduced from a mean 14° (range, 6° to 26°) to 6° (range, -1° to 24°). Two cases showed recurrent patellofemoral instability. Mean Kujala, KOOS and IKDC score were respectively 80 (± 17), 70 (± 18) and 67 (± 17) at last follow-up. Three patients required further operations, apart from removal of metal screws: arthroscopic arthrolysis for stiffness (n=1), revision for tibial tuberosity non-union (n=1), and supratrochlear exostosectomy (n=1).

DISCUSSION

Recession wedge trochleoplasty is a feasible additional procedure addressing bony trochlear abnormality in the surgical treatment of patellar instability. Our attitude is to perform it never in isolation but associated to realignment of the extensor apparatus according to the à la carte surgery concept. It seems to be effective in preventing future patellar dislocation and reducing anterior knee pain in case of painful patellofemoral instability with a major dysplastic trochlea, or in revision cases when other realignment procedures have failed.

Classification of trochlear dysplasia as predictor of clinical outcome after trochleoplasty

PURPOSE

Sulcus-deepening trochleoplasty restores the trochlear groove in patients with patellofemoral instability and underlying trochlear dysplasia. There are types of dysplasia both with (B and D) and without (A and C) a supratrochlear spur. The aim of this study was to identify influencing factors for the clinical outcome following trochleoplasty.

METHODS

Forty-four knees in 38 patients who underwent trochleoplasty for instability (type A in 9, B in 15, C in 9 and D in 11 knees) were assessed clinically with the Kujala score and radiologically with radiographs and MRI. The median follow-up was 4 (2-7.8) years.

RESULTS

At follow-up, the median Kujala score had improved from 68 (29-84) to 90 (42-100) points (P < 0.001). Instability (P < 0.001) and pain (P = 0.027) decreased significantly, but in 3 knees, pain was worse postoperatively. Twenty-seven knees were ranked as excellent, 10 as good, 2 as fair and 5 as poor. Overall, dysplasia types B and D benefited more from surgery than types A and C. The postoperative MRI revealed no chondrolysis or subchondral necrosis, but deterioration of cartilage on the lateral trochlear facet was identified.

CONCLUSION

Trochleoplasty is a useful and reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. While improved stability is predictable, pain is less predictable and may even increase following surgery. The overall results were directly dependent on the type of the dysplasia, with a significantly better clinical outcome in type B and D. The clinical relevance of this study is that severe dysplasia can successfully be treated with trochleoplasty.

LEVEL OF EVIDENCE

III.

Gracilis tendon transfer associated with distal alignment for patella alta with recurrent dislocations: an original surgical technique

Many surgical techniques for the medial patellofemoral ligament have recently been suggested, all of which included problems identifying the femoral anchorage point and determining the proper extent of knee flexion for the transplant. P. Burdin proposed a different and original approach consisting in performing a gracilis muscle transfer to the medial edge of the patella, thus obtaining progressive tension of the transfer during knee flexion by means of the myotatic reflex. We report the results herein. We retrospectively assessed 17 knees treated for patellofemoral instability using this technique. Two cases presented subjective patellofemoral instability and 15 presented objective patellofemoral instability. The patients' mean age was 17.4 years (range, 8-47 years) during the first episode of dislocation. Two cases of instability were secondary to advanced neuromuscular disease. Two knees had already undergone two stabilization attempts. Fifteen knees presented trochlear dysplasia (four stage A, eight stage B, and three stage C). The mean age at surgery was 28.2 years (range, 16-47 years). In 15 cases, the gracilis transfer was associated with lowering the anterior tibial tuberosity (mean, 10mm). No patellar fracture occurred. A persistent sensory deficit of the anterior branch of the internal saphenous nerve was observed in 15 cases. One knee remained painful and retained subjective instability; total knee arthroplasty was performed 3 years after the intervention. The mean follow-up at revision was 5.5 years (range, 1.5-16.5 years). No recurrence of dislocation was reported. Eight cases retained subjective instability. The SF-36 and IKDC scores were good or excellent in 12 cases and the KOOS was good or excellent in 13 cases. Radiologically, patellar tilt persisted in six cases out of 14, translation persisted in two cases out of 14, and secondary patella baja was observed in one. Medial patellofemoral osteoarthritis was observed in five cases: one case IWANO stage I and four cases IWANO stage II. These satisfactory results seem stable over time and were acquired using a simple procedure with reduced morbidity, making it possible to avoid significant displacement of the anterior tibial tuberosity and stabilize the extensor apparatus. It can also be hoped that the onset of secondary patellofemoral osteoarthritis, undoubtedly inevitable, has been delayed.

The role of trochlear dysplasia in patellofemoral instability

Trochlear dysplasia is characterized by abnormal trochlear morphology and a shallow groove. It is associated with recurrent patellar dislocation, but it is unclear whether the dysplasia is congenital, the result of lateral tracking and chronic instability, or caused by a combination of factors. Lateral radiographs elucidate the crossing sign and characteristic trochlear prominence. Recurrent patellofemoral instability is multifactorial, and each component must be considered in determining treatment. Managing other factors associated with recurrent instability may compensate for a deficient trochlea and provide stability. Medial patellofemoral ligament reconstruction is recommended for patellofemoral instability in the presence of trochlear dysplasia in patients without patella alta or increased tibial tubercle-trochlear groove distance. Trochleoplasty should be reserved for severe dysplasia in which patellofemoral stability cannot otherwise be obtained.

The arthroscopic deepening trochleoplasty

Since a dysplastic trochlea has been identified as the main pathomorphology in recurrent patellofemoral instability, trochleoplasty became a surgical solution in some of these cases. However, in comparison to other surgical procedures stabilizing the patellofemoral joint, trochleoplasty is a major operation with an arthrotomy, and associated typical risks of open surgery such as arthrofibrosis. Therefore, we developed a technique to perform an arthroscopic deepening trochleoplasty via suprapatellar portals using shaver burrs. Comparable to the open procedure, a cartilage flake is released and a new bony trochlea is created according to the normal anatomy. Then, the cartilage flake is re-fixated using Vicryl tapes and anchors. This method seems to be an obvious advantage in patellofemoral surgery, since an arthrotomy can be avoided, and postoperative pain as well as soft tissue healing time can be reduced.

The sulcus deepening trochleoplasty-the Lyon's procedure

Sulcus deepening trochleoplasty is a technically demanding procedure with precise indications: high grade trochlear dysplasia with patellar instability and/or abnormal tracking. The main goal is to decrease the prominence of the trochlea and to create a new groove with normal depth, thus optimising patellar tracking. Associated abnormalities should be specifically treated. Recurrence of instability is very rare after this procedure and is more likely to result from missed associated abnormalities. Although results seem very good in terms of instability, further evidence is still needed since the groups of patients in the published series are heterogeneous. Trochleoplasty is not indicated for patellofemoral arthritis or pain. As any surgical procedure, sulcus deepening trochleoplasty is liable to complications.

Patellar instability

Recurrent patellar instability can result from osseous abnormalities, such as patella alta, a distance of >20 mm between the tibial tubercle and the trochlear groove, and trochlear dysplasia, or it can result from soft-tissue abnormalities, such as a torn medial patellofemoral ligament or a weakened vastus medialis obliquus. Nonoperative treatment includes physical therapy, focusing on strengthening of the gluteal muscles and the vastus medialis obliquus, and patellar taping or bracing. Acute medial-sided repair may be indicated when there is an osteochondral fracture fragment or a retinacular injury. The recent literature does not support the use of an isolated lateral release for the treatment of patellar instability. A patient with recurrent instability, with or without trochlear dysplasia, who has a normal tibial tubercle-trochlear groove distance and a normal patellar height may be a candidate for a reconstruction of the medial patellofemoral ligament with autograft or allograft. Distal realignment procedures are used in patients who have an increased tibial tubercle-trochlear groove distance or patella alta. The degree of anteriorization, distalization, and/or medialization depends on associated arthrosis of the lateral patellar facet and the presence of patella alta. Associated medial or proximal patellar chondrosis is a contraindication to distal realignment because of the potential to overload tissues that have already undergone degeneration.

The effect of trochleoplasty on patellar stability and kinematics

Objective patellar instability has been correlated with dysplasia of the femoral trochlea. This in vitro study tested the hypothesis that trochleoplasty would increase patellar stability and normalise the kinematics of a knee with a dysplastic trochlea. Six fresh-frozen knees were loaded via the heads of the quadriceps. The patella was displaced 10 mm laterally and the displacing force was measured from 0° to 90° of flexion. Patellar tracking was measured from 0° to 130° of knee flexion using magnetic sensors. These tests were repeated after raising the central anterior trochlea to simulate dysplasia, and repeated again after performing a trochleoplasty on each specimen. The simulated dysplasia significantly reduced stability from that of the normal knee (p < 0.001). Trochleoplasty significantly increased the stability (p < 0.001), so that it did not then differ significantly from the normal knee (p = 0.244). There were small but statistically significant changes in patellar tracking (p< 0.001).

This study has provided objective biomechanical data to support the use of trochleoplasty in the treatment of patellar instability associated with femoral trochlear dysplasia.

A prospective evaluation of trochleoplasty for the treatment of patellofemoral dislocation and instability

Trochlear dysplasia is a developmental condition characterised by an abnormally flat or dome-shaped trochlea and is an important contributory factor to patellofemoral instability and recurrent dislocation. We studied prospectively a series of 54 consecutive patients (59 knees) with patellofemoral instability secondary to trochlear dysplasia, who were treated by a trochleoplasty by a single surgeon between June 2002 and June 2007. Pre- and post-operative scores were assessed by the patients and a satisfaction questionnaire was completed. Of the 54 patients (59 knees) in the series, 39 (44 knees) were female and 15 (15 knees) were male. Their mean age at surgery was 21 years and 6 months (14 years 4 months to 33 years 11 months). In 40 patients (42 knees) the mean follow-up was for 24 months (12 to 58). One patient was unable to attend for follow-up. An analysis of the results of those patients followed up for at least 12 months showed a statistically significant improvement in outcome (p < 0.001 for all scores). Overall, 50 patients (92.6%) were satisfied with the outcome of their procedure. The early results of trochleoplasty are encouraging in this challenging group of patients.

Assessment and management of chronic patellofemoral instability

Chronic patellofemoral instability can be a disabling condition. Management of patients with this condition has improved owing to our increased knowledge of the functional anatomy of the patellofemoral joint. Accurate assessment of the underlying pathology in the unstable joint enables the formulation of appropriate treatment. The surgical technique employed in patients for whom non-operative management has failed should address the diagnosed abnormality. We have reviewed the literature on the stabilising features of the patellofemoral joint, the recommended investigations and the appropriate forms of treatment.