Trochleoplasty as a Solitary Treatment for Recurrent Patellar Dislocation Results in Good Clinical Outcome in Adolescents

Thick-shell sulcus-deepening trochleoplasty for recurrent patellar dislocation leads to clinically meaningful improvements and high patient satisfaction in adolescents with open physes

OBJECTIVES

To evaluate clinical and radiological outcomes of thick-shell, sulcus-deepening trochleoplasty in patients with open distal femoral physes and less than two years of growth remaining. We hypothesized that patients would have clinical and radiographic improvements in addition to high patient-reported outcomes following thick-shell, sulcus-deepening trochleoplasty.

METHODS

Bone age was determined on preoperative magnetic resonance imaging (MRI) using the Pennock Knee Bone Age Atlas. Pre- and postoperative radiographs were used to measure the anatomic lateral distal femoral angle (aLDFA) and Blumensaat angle. International Knee Documentation Committee (IKDC), Kujala, and numerical patient satisfaction scores were assessed. Pre- and postoperative aLDFA and Blumensaat angles as well as patient-reported outcomes were analyzed via the Wilcoxon signed-rank test.

RESULTS

Seventeen adolescents (21 knees) with DeJour Types B and D trochlear dysplasia and open distal femoral physes underwent Dejour thick-shell, sulcus-deepening trochleoplasty at a single institution. In twelve females (16 knees, 76.2%) the median chronological and bone ages at the time of operation were 14.9 and 14.3 years, respectively. In 5 males (5 knees, 27.7%), the median chronological and bone ages at the time of operation were 15.7 and 15.2 years, respectively. Mean follow-up time was 64 months postoperatively. Physes were closed in all knees at the time of final clinical and radiographic follow-up. The mean change in aLDFA and Blumensaat Angle was 0.73 (p ​= ​0.1074, 95% CI -0.09-1.57) and 0.88° (p ​= ​0.0477, 95% CI 0.10-1.88), respectively. Median IKDC scores improved from 57.3 preoperatively to 90.9 postoperatively, for a mean difference of 26.1 (p ​= ​0.00064, 95% CI 18.0-34.2). Median Kujala scores improved from 55.0 preoperatively to 95.0 postoperatively, for a mean change of 30.2 (p ​= ​0.0008, 95% CI 19.6-40.8). Overall mean numerical patient satisfaction was high (mean 9.26/10). One of 21 knees (4.8%) underwent additional surgery to address recurrent patellar instability.

CONCLUSION

Thick-shell sulcus-deepening trochleoplasty for addressing recurrent lateral patellar instability in patients with open distal femoral physes and less than two years of growth remaining is safe and provides clinically meaningful improvements in addition to high patient satisfaction when combined with other patellar stabilization procedures.

LEVEL OF EVIDENCE

IV, Retrospective Case Series.

Recurrent patellar dislocation patients with high-grade J-sign have multiple structural bone abnormalities in the lower limbs

PURPOSE

To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD).

METHODS

A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ2 test was used to compare composition ratio differences of structural bone abnormalities among the groups.

RESULTS

A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001).

CONCLUSION

In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures.

LEVEL OF EVIDENCE

Level III.

Isolated Medial Patellofemoral Ligament Reconstruction Results in Lower Failure and Complication Rates Than Isolated Trochleoplasty and Tibial Tubercle Osteotomy: A Systematic Review

PURPOSE

To evaluate outcomes and complications of isolated medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy (TTO), and trochleoplasty for management of patellar instability.

METHODS

A query of Scopus, PubMed, Google Scholar, Cochrane CENTRAL Register of Controlled Trials, and the Cochrane Database of Systematic Reviews was performed in accordance with 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies reported clinical outcome data after isolated MPFLR, TTO, or trochleoplasty for patellar instability with a minimum 12-month follow-up. Meta-analysis and data aggregation was not performed.

RESULTS

Thirty-six studies (5 trochleoplasty, 14 TTO, and 18 MPFLR) consisting of 1,389 patients (114 trochleoplasty, 374 TTO, and 1,001 MPFLR) were included. Risk of bias was assessed with the Methodological Index for Non-Randomized Studies score, which ranged from 11 to 12 in trochleoplasty, 10 to 18 in TTO, and 8 to 18 in MPFLR studies. Patient-reported outcome measures, including Lysholm score (trochleoplasty: 51.1-71 to 71-95; TTO: 57-63.3 to 84-98; MPFLR: 37.4-59.1 to 74-92.5), Kujala score (trochleoplasty: 56-71 to 78-92; TTO: 48.6-68 to 78-92; MPFLR: 53.3-60 to 81.5-92), visual analog scale for pain (trochleoplasty: 52-25; TTO: 54-76 to 14-27; MPFLR: 29 to 17, out of 100), and Tegner score (TTO: 3-4 to 3-4; MPFLR: 2.5-6 to 4.9-5), improved after all surgeries. Failure rates ranged from 0% to 33.3% after MPFLR, 0% to 30.8% after TTO, and 5.3% to 40% after trochleoplasty. Complication rates ranged from 0% to 14.7% after MPFLR, 1.6% to 58.3% after TTO, and 8% to 26.3% after trochleoplasty.

CONCLUSIONS

Isolated MPFLR, TTO, or trochleoplasty may be effective treatment options for patellar stabilization. Although failure rates were highest after isolated trochleoplasty and complication rates were highest after TTO, these procedures are not interchangeable as each addresses a specific pathology.

LEVEL OF EVIDENCE

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

Trochleoplasty Provides Good Outcomes for Recurrent Patellofemoral Dislocations with No Clear Superiority across Different Techniques

Background: Literature is sparse on outcome comparisons between different trochleoplasty techniques in the treatment of patella instability. To date, it is unclear whether there is a technique that offers superior outcomes. This systematic review and meta-analysis aims to compare and evaluate the outcomes of trochleoplasty techniques in the treatment of patellofemoral instability in trochlea dysplasia to establish whether there is an ideal choice of trochleoplasty technique for superior outcomes. Methods: 21 studies involving 880 knees were included. The mean age of the patients was 21.7 years (range 8-49 years). Mean follow-up timeframe of 43.5 months (range 8.8-100 months). Clinical outcomes assessed included rates of recurrence of patellofemoral dislocation, patient satisfaction, Kujala score, International Knee Documentation Committee (IKDC) score, Tegner score, and Lysholm score. Egger's test showed no publication bias across all outcomes assessed. Results: Favourable results were seen across all outcomes assessed and patient satisfaction. Improvements were seen with Kujala, IKDC, and Lysholm scores. Tegner scores showed good return to function. Post-operative dislocation and complication rates were low across the different techniques. Meta-regression for Kujala and IKDC scores showed good outcomes regardless of trochleoplasty technique used (Kujala, p = 0.549, relative risk 492.06; IKDC, p = 0.193, RR 0.001). The exact risk that trochleoplasty poses to the cartilage remains uncertain, as no study had a conservatively managed arm for comparison. Conclusions: Trochleoplasty yielded good outcomes irrespective of technique used with no clear superiority demonstrated in any technique in terms of outcome scores, satisfaction, post-operative dislocation rates or complications.

No significant difference in thick versus thin osteochondral flap trochleoplasty in the treatment of trochlear dysplasia: A systematic review

PURPOSE

Trochleoplasty has become increasingly utilised to address patellar instability in the setting of severe trochlear dysplasia. There remains a paucity of literature on the outcomes of 'thick'- versus 'thin'-osteochondral flap trochleoplasty. The purpose of this study is to compare clinical and radiographic outcomes between patients with patellar instability with symptomatic trochlear dysplasia treated using a 'thick' versus 'thin' osteochondral flap trochleoplasty.

METHODS

A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Quality assessment of final articles was conducted by two blinded reviewers. Articles were separated based on the use of a 'thick' versus 'thin' flap trochleoplasty. Data collection consisted of recording the following variables: patient demographics, indications for trochleoplasty, mean follow-up time, additional procedures performed during trochleoplasty, patient-reported outcome measures (PROMs), radiographic outcomes (tibial tubercle-trochlear groove [TT-TG] distance, Caton-Deschamps Index [CDI] and sulcus angle [SA]) and the incidence of any postoperative complications and patellar redislocation rates.

RESULTS

A total of 24 studies, consisting of 927 patients, were identified as meeting inclusion criteria. A total of five papers described a 'thick' flap technique, while 19 papers described the use of a 'thin' flap technique. No significant difference in the mean improvement of Kujala scores was appreciated when comparing 'thick' versus 'thin' techniques (p > 0.05). Improvements in mean radiographic outcomes based on TT-TG, CDI and SA were observed in both 'thick' and 'thin' flap trochleoplasty groups. The overall redislocation rate was 0.35%.

CONCLUSION

No significant difference in Kujala scores was observed in patients undergoing trochleoplasty utilising 'thick' versus 'thin' technique, while improvements in mean TT-TG, CDI and SA were noted in both technique groups, with an overall redislocation rate of 0.35%.

LEVEL OF EVIDENCE

Level IV.

Is the patella apprehension test a valid diagnostic test for patellar instability? A systematic review

Introduction

Patellar instability can arise from a traumatic event with anatomical predisposing factors increasing the risk of dislocation. Accurate diagnosis is required to initiate appropriate treatment. We aimed to evaluate the patella apprehension test (PAT) as a method to diagnose patellar instability.

Methods

The PRISMA diagnostic test accuracy checklist was followed. The review protocol was registered on PROSPERO with registration number CRD42022357898. Electronic databases, currently registered studies, conference proceedings and the reference lists of included studies were searched. A narrative synthesis evaluated the validity of the PAT as a method of diagnosing patellar instability.

Results

A total of 4867 records were screened in the initial search. Of these, 34 articles satisfied the inclusion criteria, assessing 1139 knees of 1046 patients. The PAT was found to have a high sensitivity and specificity. Its intra and inter-rater reliability was highly variable among studies. Studies reporting patellar instability correction following surgery also found a decrease in the number of patients exhibiting a positive PAT.

Conclusion

Current evidence suggests that the PAT has a high sensitivity and specificity. The intra- and inter-rater validities of the PAT are widely variable due to its subjective nature. Thus, though the PAT can be used to provide a provisional clinical diagnosis of patellar instability, formal functional assessment and imaging should be performed to confirm the diagnosis. Further research should explore the association between a positive PAT and anatomical parameters. In addition, studies comparing the accuracy of the PAT and radiological investigations should be performed.

What is the J-sign and why is it important?

PURPOSE OF REVIEW

Recurrent lateral patellofemoral instability is a complex condition that requires a thorough evaluation to optimize treatment. The J-sign test is classically part of the physical examination, but its significance and importance remain unclear. This review aims to describe how to perform the test and classify the observation as well as to analyze the most recent literature on its clinical applications.

RECENT FINDINGS

The J-sign test has been described as positive (present) or negative (absent), and classified using the quadrant method and the Donnell classification. Suboptimal inter-rater reliability has been shown for both classifications, making comparison between clinicians and studies challenging. The J-sign is most predominantly associated with patella alta, trochlear dysplasia, lateral force vector, and rotational abnormalities. A growing number of studies have shown a correlation between a positive J-sign and lower clinical outcome scores and higher rate of surgical failure.

SUMMARY

The J-sign is an important aspect of the physical examination in patients with recurrent lateral patellofemoral instability. Although there is no consensus on how to perform or classify the test, it can be used as a marker of severity of patellofemoral instability and is one of the tools available to guide the treatment plan.

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.

Inter-rater Reliability of the Classification of the J-Sign Is Inadequate Among Experts

OBJECTIVE

The purpose of this study was to determine the inter-rater and intra-rater reliability of the symmetry, classification, and underlying pathoanatomy associated with the J-sign in patients with recurrent lateral patellofemoral instability.

STUDY DESIGN

Blinded, inter-rater reliability study.

SETTING

N/A.

PARTICIPANTS

Thirty patellofemoral joint experts.

INTERVENTIONS

Thirty clinicians independently assessed 30 video recordings of patients with recurrent lateral patellofemoral instability performing the J-sign test.

MAIN OUTCOME MEASURES

Raters documented J-sign symmetry and graded it according to the quadrant and Donell classifications. Raters indicated the most significant underlying pathoanatomy and presence of sagittal plane maltracking. Intra-rater reliability was assessed by 4 raters repeating the assessments. Mean pairwise simple and/or weighted Cohen's kappa were performed to measure inter-rater and intra-rater reliability, as well as calculation of percent agreement.

RESULTS

J-sign symmetry demonstrated fair inter-rater reliability (k = 0.26), whereas intra-rater reliability was moderate (k = 0.48). Inter-rater reliability for the quadrant and Donell classifications indicated moderate agreement, k = 0.51 and k = 0.49, respectively, whereas intra-rater reliability was k = 0.79 and k = 0.72, indicating substantial agreement. Inter-rater reliability of the foremost underlying pathoanatomy produced only slight agreement (k = 0.20); however, intra-rater reliability was substantial (k = 0.68). Sagittal plane maltracking demonstrated slight inter-rater agreement (k = 0.23) but substantial intra-rater agreement (k = 0.64).

CONCLUSIONS

The symmetry, classification, and underlying pathoanatomy of the J-sign demonstrated fair to moderate inter-rater reliability and moderate to substantial intra-rater reliability among expert reviewers using video recordings of patients with recurrent lateral patellofemoral instability. These findings suggest individual raters have a consistent standard for assessing the J-sign, but that these standards are not reliable between assessors.

LEVEL OF EVIDENCE

III.

Radiographic Evaluation of Pediatric Patients with Patellofemoral Instability

PURPOSE OF REVIEW

The purpose of this review is to highlight the radiographic assessments of utility in the evaluation of a pediatric patient with patellofemoral instability to facilitate a thorough work-up. Understanding of these measures is useful in understanding evolving research in this field, providing accurate patient risk assessment, and appropriately directing surgical decision-making.

RECENT FINDINGS

Recent literature has broadened the radiographic characterization of the pediatric patellar instability and its anatomic risk factors. Knee MRI can inform the assessment of skeletal maturity and novel axial alignment measurements may enhance our identification of patients at increased risk of recurrent instability. Additional improvements have been made in the objective measurement and classification of trochlear dysplasia. Knee MRI-based skeletal age assessments may obviate the need for hand bone age assessments in growing children with patellofemoral instability. Novel objective measures exist in the evaluation of pediatric patellar instability both in the assessment of axial alignment and trochlear dysplasia. Future work should focus on how these measures can aid in guiding surgical decision-making.

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BACKGROUND

Trochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty.

METHODS

Between 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient's latest follow-up assessment.

RESULTS

The mean age at operation was 22y (SD ± 4.7, range 14-37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12-60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m²) was associated with inferior outcomes.

CONCLUSION

Trochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.

Complications and outcomes of trochleoplasty for patellofemoral instability: A systematic review and meta-analysis of 1000 trochleoplasties

BACKGROUND

Trochleoplasty is an effective patellar stabilization procedure; however, it is associated with a risk of complications that cannot be ignored. Prior systematic reviews on this topic did not include more recent studies reporting important outcomes, particularly the long-term results of lateral elevation trochleoplasty. This led us to carry out a new meta-analysis of the various trochleoplasty procedures to specify: (1) the recurrence rate of patellofemoral dislocation; (2) the complication rates and; (3) the clinical outcomes.

PATIENTS AND METHODS

Studies reporting complications and clinical outcomes of trochleoplasty, whether or not it was combined with other procedures for patellofemoral instability, were identified in the MEDLINE, Embase, Scopus, Cochrane Library, Web of Science databases and by searching the grey literature. The primary endpoint was the recurrence of patellofemoral dislocation while the secondary endpoints were objective patellofemoral instability without dislocation, stiffness, patellofemoral osteoarthritis, subsequent surgeries and various clinical outcome scores. The results were combined in a random-effects model (weighing factor: inverse variance) when the heterogeneity was less than 80%.

RESULTS

Twenty-eight studies were included: 5 featured lateral elevation trochleoplasty, 10 about the Dejour deepening trochleoplasty, 12 about the Bereiter deepening trochleoplasty and 1 about the recession wedge trochleoplasty. A total of 1000 trochleoplasty procedures were done in 890 patients who had a follow-up of 1 to 25 years. There were 24 cases of recurrent dislocation (24/994 [2.4%]; this outcome was not reported for 6 trochleoplasties). The Dejour deepening trochleoplasty was the most effective with only 1 recurrence in 349 knees (0.28%). For the other complications, residual patellar instability without dislocation occurred in 82 of 754 knees (8% [95% CI: 3-14%]), patellofemoral osteoarthritis in 117 of 431 knees (27%), stiffness in 59 of 642 knees (7% [95% CI: 3-12%]) and the need for subsequent surgery in 151 of 904 knees (17%).

DISCUSSION

This study found a low recurrence rate for patellofemoral dislocation and residual instability. The incidence of stiffness, patellofemoral osteoarthritis and subsequent surgery remains high but differs greatly between studies. This meta-analysis showed a very large disparity between studies for most complications, which justifies the need for randomized and comparative studies to establish the role of trochleoplasty procedures in the treatment algorithm for patellar instability.

LEVEL OF EVIDENCE

IV; systematic review and meta-analysis.

Patellar Apprehension Is Reduced in Most but Not All Patients After Successful Patellar Stabilization

BACKGROUND

The clinical sign of patellar laxity and the associated symptom of apprehension are mainstays of the physical examination of patellofemoral instability. The apprehension test is widely used as a diagnostic tool and also as an outcome following patellofemoral stabilization surgery. Despite widespread use, the validity, reliability, and responsiveness of the apprehension test have not been established.

PURPOSE

The primary purpose was to evaluate patellar apprehension in patients with recurrent patellofemoral instability to determine if the apprehension test is valid, reliable, and responsive to change after medial patellofemoral ligament (MPFL) reconstruction. The secondary purposes were to concurrently validate patient-rated to surgeon-rated apprehension and to correlate patient-rated apprehension with pathoanatomic characteristics and quality-of-life scores.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

A total of 89 patients underwent an MPFL reconstruction and were assessed preoperatively and at 6, 12, and 24 months postoperatively. The patellar apprehension test was performed in neutral extension and 30° of knee flexion. Patient- and surgeon-rated apprehension were graded on a 10-cm visual analog scale (VAS), and the quality of the apprehension symptoms were recorded. Risk factors for patellofemoral instability were documented, and the Banff Patellofemoral Instability Score 2.0 (BPII 2.0) was used to measure disease-specific quality of life.

RESULTS

The patient-rated and surgeon-rated apprehension VAS scores were statistically significantly reduced from pre- to postoperatively (P < .001, large effect size) for the neutral extension and 30° of flexion apprehension tests. Postoperatively, over 56% of patients reported a negative apprehension test. Up to 15.7% of patients with positive preoperative apprehension did not demonstrate a reduction postoperatively. Patients consistently graded their apprehension symptoms higher in both quantity and quality than the surgeon. The intraclass correlation coefficient (ICC [2, k]) assessing the preoperative patient and surgeon VAS scores revealed moderate interrater reliability in neutral extension (r = 0.60) and weak interrater reliability in 30° of flexion (r = 0.42). The postoperative ICC (2, k) demonstrated strong interrater reliability for both neutral extension (r = 0.74) and 30° of flexion (r = 0.73). The symptoms of apprehension (physical, emotional, and/or physiological) decreased substantially after surgery. The correlation of postoperative patient-rated apprehension VAS and BPII 2.0 scores demonstrated that less residual patellar apprehension was associated with higher BPII scores in neutral extension (r = -0.35, P = .001). There were no statistically significant correlations revealed between the patient-rated postoperative apprehension VAS and pathoanatomic risk factors. BPII 2.0 scores improved pre- to postoperatively from a mean of 27.6 (SD, 15.7) to 74.3 (SD, 18.3). Three patients (3.4%) sustained a patellar dislocation postoperatively.

CONCLUSION

The patellar apprehension test demonstrated strong validity and responsiveness to change. Interrater reliability ranged from weak to strong. There was a statistically significant reduction in apprehension after patellofemoral stabilization in the majority of patients. Patients graded their apprehension symptoms significantly higher in both quantity and quality than the surgeon. Persistent patellar apprehension after stabilization was correlated with lower quality-of-life scores. No relationship could be found between persistent apprehension and patellofemoral risk factors. These results suggest that use of the apprehension tests as an outcome is inappropriate until further validation is performed.

Assessment and Trends of the Methodological Quality of the Top 50 Most Cited Articles on Patellar Instability

Background

Studies with a low level of evidence (LOE) have dominated the top cited research in many areas of orthopaedics. The wide range of treatment options for patellar instability necessitates an investigation to determine the types of studies that drive clinical practice.

Purpose

To determine (1) the top 50 most cited articles on patellar instability and (2) the correlation between the number of citations and LOE or methodological quality.

Study Design

Cross-sectional study.

Methods

The Scopus and Web of Science databases were assessed to determine the top 50 most cited articles on patellar instability between 1985 and 2019. Bibliographic information, number of citations, and LOE were collected. Methodological quality was calculated using the Modified Coleman Methodology Score (MCMS) and the Methodological Index for Non-Randomized Studies (MINORS). Mean citations and mean citation density (citations per year) were correlated with LOE, MCMS, and MINORS scores.

Results

Most studies were cadaveric (n = 10; 20.0%), published in the American Journal of Sports Medicine (n = 13; 26.0%), published between 2000 and 2009 (n = 41; 82.0%), and conducted in the United States (n = 17; 34.0%). The mean number of citations and the citation density were 158.61 ± 59.53 (range, 95.5-400.5) and 12.74 ± 5.12, respectively. The mean MCMS and MINORS scores were 59.62 ± 12.58 and 16.24 ± 3.72, respectively. No correlation was seen between mean number of citations or citation density versus LOE. A significant difference was found in the mean LOE of articles published between 1990 and 1999 (5.0 ± 0) versus those published between 2000 and 2009 (3.12 ± 1.38; P = .03) and between 2010 and 2019 (3.00 ± 1.10; P = .01).

Conclusion

There was a shift in research from anatomy toward outcomes in patellar instability; however, these articles demonstrated low LOE and methodological quality. Higher quality studies are necessary to establish informed standards of management of patellar instability.

Lateral trochlear lengthening osteotomy

INTRODUCTION

The purpose of this study was to describe the indications and technical aspects as well as evaluate the clinical and functional outcome of lengthening osteotomy of the lateral trochlear ridge in patients with patellofemoral pain and/or patella instability and presence of trochlear dysplasia Dejour type A or lack of Dejour type dysplasia and short lateral articular trochlea.

MATERIALS AND METHODS

Six consecutive adult patients were treated with a lateral trochlear lengthening osteotomy. Five patients received a concomitant medial patellofemoral ligament reconstruction. Three patients had prior patella stabilization surgeries. Trochlea dysplasia (Dejour classification), Caton-Dechamps index, tibial tubercle trochlear groove (TT-TG) distance, patellar tilt and lateral condylar index were measured in preoperative MRIs. Clinical and functional evaluation included the Kujala Anterior Knee Pain Scale, the Lysholm Knee Score, the Tegner Activity Score, a subjective evaluation form and isokinetic muscle strength.

RESULTS

Four patients had a Dejour type A dysplasia, two patients had no dysplasia. The mean (range) Caton-Dechamps index was 1.09 (0.95-1.16), TT-TG distance 10.9 mm (9.2-15.6 mm), patellar tilt 15° (4-32°) and lateral condylar index 82.0% (74-90%). One patient was lost to follow up, all others were followed for 2-5 years. All patients were satisfied with the clinical outcome. The Lysholm score increased from 55 (37-79) to 89 (76-100), the Tegner activity score from 3.6 (2-6) to 5.6 (5-7). The Kujala score postoperative was 90 (75-96). Some but not all patients had full strength recovery compared to the contralateral leg.

CONCLUSION

We recommend measuring the lateral condylar index and considering the indication of a lateral trochlear lengthening osteotomy as an additional or isolated procedure in selected patients with trochlear dysplasia Dejour type A or lack of dysplasia and short lateral articular trochlea depending on the extent of the patellar instability.

LEVEL OF EVIDENCE

Level IV, Case Series.

TRIAL REGISTRATION NUMBER

NCT04378491, clinicaltrials.gov, May 7, 2020.

Sulcus-Deepening Trochleoplasty as an Isolated or Combined Treatment Strategy for Patellar Instability and Trochlear Dysplasia: A Systematic Review

Purpose

To highlight the indications and outcomes for sulcus-deepening trochleoplasty, when used as an isolated procedure as well as in combination with other stabilization techniques for patellar instability.

Methods

We performed a systematic review focused on outcomes and complications following trochleoplasty performed either as an isolated procedure or in combination with other procedures to address patellar instability. Inclusion criteria included studies in English that reported on outcomes following primary open trochleoplasty, including Kujala scores and recurrent instability or dislocation events.

Results

Twelve papers including 702 patients who underwent sulcus-deepening trochleoplasty were included. A total of 504 patients underwent isolated sulcus-deepening trochleoplasty, whereas 198 patients underwent trochleoplasty in combination with 1 or more additional stabilization procedures. In total, 67% of patients were female compared with 33% male. The procedure was done was a primary surgical intervention 74% of the time. Postoperative Kujala scores for isolated trochleoplasty ranged from 80 to 92, whereas those for combined stabilization procedures ranged from 76 to 95. The dislocation rate among the studies ranged from 0 to 8%. There was a persistent J-sign in 0 to 12% of treated knees among all studies, and a persistent apprehension test in 0 to 29% of treated knees. Return to play ranged from 65% to 83% in studies in which this was reported as an outcome.

Conclusions

Sulcus-deepening trochleoplasty performed for recurrent patellar instability in the setting of trochlear dysplasia results in improved Kujala scores and a low redislocation rate, when performed as an isolated procedure or in combination with other stabilization procedures. Greater-level evidence is needed to better evaluate the overall efficacy of this procedure in addressing patellar instability.

Level of Evidence

Level of Evidence, IV; Systematic review of level III and IV studies.

A modification of the Bereiter trochleoplasty: indications, technique and outcomes

INTRODUCTION

The Bereiter technique is one recognised method of trochleoplasty that was described using a lateral para-patellar approach. We present our surgical technique and outcomes of this procedure using a medial para-patellar approach allowing for accurate soft tissue balancing of the patella.

METHODS

In total, 27 consecutive patients underwent a Bereiter trochleoplasty using a medial approach. Patients completed pre- and post-operative Kujala scores. All patients' medical records and imaging were reviewed to identify pre-operative indications, complications and re-dislocations.

RESULTS

Data were collected on 31 trochleoplasty procedures in the 27 patients. Mean age at time of surgery was 25 (17-39), and 16 patients were females. Follow-up ranged from 13 to 60 months. All patients had severe trochlea dysplasia with recurrent instability. Three patients underwent a planned tibial tubercle transfer for a pre-operative raised TT-TG distance. The mean pre-operative Kujala score was 53.9 (26-79) rising to 91.2 (88.6-100) post-operatively. A low post-operative Kujala score seen in patients had a significantly lower than average pre-operative score. No patients had any further dislocations following surgery. Two patients complained of significant stiffness in the early post-operative period. No patients required additional procedures to adequately balance the patella following the trochleoplasty combined with medial reefing plus lateral release involved in this modified technique.

CONCLUSION

A modified Bereiter trochleoplasty using a medial rather than a lateral para-patella approach gives excellent results.

LEVEL OF EVIDENCE

Level II evidence.

High failure rate 10.8 years after vastus medialis transfer and lateral release (Green's quadricepsplasty) for recurrent dislocation of the patella

PURPOSE

In adolescent patients with recurrent patellar dislocation, the Green's quadricepsplasty stabilizes the patella in a combination of a lateral release, a transfer of the medial head of the quadriceps onto the lateral part of the patella and an imbrication of the medial patellar retinaculum and joint capsule. This study aimed to evaluate the long-term performance, considering re-dislocations and functional outcomes. We hypothesized a high failure rate in the long term.

METHODS

In this single surgeon and single center study 26 knees in 23 patients (mean age 14.2 years; 4-22 years, 18 females) with recurrent patellofemoral dislocation underwent a vastus medialis transfer, medial reefing and lateral release as it was described by Green in 1965 with a mean follow-up 10.8 years (6-24 years). Clinical assessment was carried out with an IKDC-score (international knee documentation committee) and a self-assessment for each knee separately. The radiologic evaluation included measurement of the patella height, the grade of trochlear dysplasia and the sulcus angle.

RESULTS

In 12 of 26 cases (46.2%) the patella did not re-dislocate after vastus medialis transfer and lateral release. In 11 of 26 cases (42.3%), the patients described the function of their knees as normal or nearly normal according to IKDC after the surgical treatment without any re-dislocation. In 14 of 26 cases (53.8%), the patella re-dislocated. 7 of these 14 cases underwent a revision operation. Re-dislocations occurred after a mean interval of 21 months after the index procedure. In only 2 of 26 cases (7.7%) the patients returned to sports.

CONCLUSION

Green's procedure to stabilize patellofemoral instabilities results in a high failure rate on the long-term and low subjective assessments. We do not recommend performing vastus medialis transfer, medial imbrication and lateral release as a standalone technique.

LEVEL OF EVIDENCE

IV.

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.

Precise Arthroscopic Mini-trochleoplasty and Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability With Severe Trochlear Dysplasia

More than 100 surgical procedures have been reported to address recurrent patellar instability. Trochlear dysplasia is the most common finding among the anatomic risk factors for recurrent patellar instability. Various studies have shown that trochleoplasty combined with medial patellofemoral ligament reconstruction is an effective technique to treat recurrent patellar instability. Nevertheless, trochleoplasty is still a daunting procedure for surgeons because of its multiple and gloomy complications. This article introduces a technique to treat recurrent patellar instability with severe trochlear dysplasia: precise arthroscopic mini-trochleoplasty (PAM trochleoplasty) combined with medial patellofemoral ligament reconstruction. This technique precisely removes the supratrochlear spur and trochlear bump, accurately reshapes the trochlear sulcus with minimal invasion and less osteotomy volume, and keeps the sulcus cartilage intact. The purpose of this technique is to develop trochleoplasty into a common and safe technique, which has good outcomes and low complications.

Sulcus Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction for Patellofemoral Instability: A 2-Year Study

PURPOSE

To evaluate outcome data of patients undergoing DeJour sulcus-deepening trochleoplasty with medial patellofemoral ligament reconstruction (MPFLR) for high-grade trochlear dysplasia at a single institution in the United States.

METHODS

A total of 67 patients (76 knees) with severe trochlear dysplasia and recurrent patellar instability were prospectively enrolled and underwent DeJour sulcus-deepening trochleoplasty with MPFLR from 2011 to 2019. Inclusion criteria included recurrent lateral patellar instability following failure of conservative treatment with radiographic evidence of severe trochlear dysplasia (DeJour types B or D). Patients with less than 2-year follow-up were excluded. Radiographic analysis, physical examination, clinical follow-up, patient demographics, and patient-reported outcome measures were obtained for all patients at each visit.

RESULTS

Forty patients (44 knees) had complete 2-year or longer follow-up and were included. The majority of patients were female (81.8%) with a mean age of 19.2 years (standard deviation [SD] 6.7; range 13.2-47.0). Follow-up ranged from 2.0 years to 6.8 years (mean 3.6 years, SD 1.35). In total, 45.5% had failed previous surgery for patellar instability. Eight knees developed arthrofibrosis and the overall reoperation rate was 27.3%. No patients had fixation failure and no further surgery was required for instability. The mean preoperative International Knee Documentation Committee score of 50.8 improved to 79.1 (P < .001), and the mean preoperative Kujala score of 56.4 improved to 86.5 (P < .001). Patients reported high satisfaction rates (mean 9.1 of 10). When applicable, 100% of patients returned to work, whereas 84.8% returned to sport. There was no significant radiographic progression of patellofemoral arthritis at a mean of 2.4 years after surgery (SD 1.7).

CONCLUSIONS

DeJour sulcus-deepening trochleoplasty combined with MPFLR and used with tibial tubercle osteotomy and lateral release is a reliable and effective treatment for recurrent patellar instability due to severe trochlear dysplasia, even in this group with many revisions of previous procedures.

LEVEL OF EVIDENCE

IV, case series.

Recurrent patellar dislocations in adolescents result in decreased knee flexion during the entire gait cycle

PURPOSE

To evaluate the kinematics/kinetics of the ankle, knee, hip in the sagittal plane in adolescents with recurrent patellar dislocation in comparison to a healthy control.

METHODS

Case-control study. Eighty-eight knees (67 patients) with recurrent patellar dislocation (mean age 14.8 years ± 2.8 SD) were compared to 54 healthy knees (27 individuals, 14.9 years  ± 2.4 SD). Kinematics/kinetics of ankle, knee, hip, and pelvis were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, Plug-in-Gait, two force plates). One cycle (100%) consisted of 51 data-points. The mean of six trials was computed.

RESULTS

The loading-response increased by 0.02 s ± 0.01SE (10.8%) with dislocations (0.98% of total gait, P < 0.01). The mid-stance-phase decreased equally (P < 0.01). Dislocation decreased knee flexion during the entire gait cycle (P < 0.01), with the largest difference during mid-stance (9.0° ± 7.2 SD vs. 18.5° ± 6.7 SD). Dislocation increased plantar-flexion during loading response 4.1° ± 0.4 SE with (P < 0.01), afterward, the dorsal-extension decreased 3.2° ± 0.3 SE, (P < 0.01). Dislocation decreased hip flexion during all phases (P < 0.01). Maximal difference: 7.5° ± 0.5 SE during mid-stance. 80% of all patients developed this gait pattern. Internal moments of the ankle increased, of the knee and hip decreased during the first part of stance.

CONCLUSION

Recurrent patellar dislocation decreases knee flexion during the loading-response and mid-stance phase. A decreased hip flexion and increased plantar-flexion, while adjusting internal moments, indicate a compensation mechanism.

LEVEL OF EVIDENCE

III.

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.

Assessing Femoral Trochlear Morphologic Features on Cross-Sectional Imaging Before Trochleoplasty: Dejour Classification Versus Quantitative Measurement

OBJECTIVE. The purpose of this study is to assess the use of cross-sectional imaging to qualitatively and quantitatively categorize trochlear dysplasia as low grade (type A) or high grade (types B-D) according to the Dejour classification. MATERIALS AND METHODS. A retrospective review of CT and MRI knee examinations performed before patients underwent deepening trochleoplasty was independently conducted by two musculoskeletal radiologists. Each case of trochlear dysplasia was qualitatively assigned a Dejour type. Subsequently, quantitative measurements of the sulcus angle, distance from the tibial tubercle to the trochlear groove, trochlear depth, lateral trochlear inclination, trochlear facet asymmetry, and degree of patellar lateralization were performed. RESULTS. A total of 35 patients (29 female patients and six male patients; mean age, 21.1 years) with 39 affected knees (17 right knees and 22 left knees) were included. Readers had exact qualitative agreement using Dejour classification for 30 of 39 knees (77% [κ = 0.77; 95% CI, 0.62-0.91]) and agreement on classification of low-grade versus high-grade dysplasia for 36 of 39 knees (92%). For these 36 knees, the mean differences in measurements of low- versus high-grade dysplasia, respectively, were as follows: for sulcus angle, 153° versus 168° (p < 0.001); for trochlear depth, 4 versus 1 mm (p < 0.001); for lateral trochlear inclination, 12 versus 7 mm (p < 0.02); and for decreased trochlear facet asymmetry, 13% versus 92% (p < 0.001). Trochlear depth, lateral trochlear inclination, and trochlear facet asymmetry were also different in comparisons of knees with Dejour type B and C trochlear dysplasia versus those with Dejour types B and D (all p < 0.05). No quantitative measurement differentiated between trochlear dysplasia of Dejour types C and D. The distance from the tibial tubercle to the trochlear groove and the degree of patellar lateralization were not statistically different between low- and high-grade dysplasia. CONCLUSION. Qualitative use of the Dejour classification accurately categorizes trochlear dysplasia as low grade or high grade in 92% of cases, with exact agreement reached in 77% of cases. Furthermore, the trochlear depth, lateral trochlear inclination, trochlear facet asymmetry, and sulcus angle can differentiate between low-grade and high-grade dysplasia, with trochlear depth, lateral trochlear inclination, and trochlear facet asymmetry useful for differentiating between Dejour types B and C and Dejour types B and D.

Validity and Reliability of the Banff Patellofemoral Instability Instrument 2.0 in an Adolescent Population

BACKGROUND

Lateral patellofemoral instability is a relatively common problem in the adolescent population. Subjective and objective patient outcomes are commonly used to evaluate treatment success or failure. The Banff Patellofemoral Instability Instrument (BPII) and Paediatric International Knee Documentation Committee (Pedi-IKDC) Subjective Knee Form are patient-reported outcome measures that have been used with an adolescent population previously. The BPII 2.0 is a shortened version of the BPII and has not been validated in an adolescent population. The purpose of the current study was to validate the BPII 2.0 with an adolescent population.

METHODS

This was a multicenter study where patients were recruited from 3 tertiary orthopaedic surgery clinics. A convenience sample (n=140 adolescent patients) with a confirmed diagnosis of lateral patellofemoral instability and who had failed conservative treatment was referred to one of the 3 orthopaedic surgeons. All patients completed the BPII 2.0 and Pedi-IKDC before their clinic appointment. Cronbach's alpha and floor/ceiling effects were used to determine the content validity of both instruments. Patients were also interviewed to ask questions about the BPII 2.0 comprehension and importance of items. One clinic site sent out the BPII 2.0 to 30 additional patients twice in 2 weeks to measure the test-retest reliability (intraclass correlation coefficient 2,k). A Pearson r correlation coefficient was used to determine the relationship between the BPII 2.0 and the Pedi-IKDC and criterion validity.

RESULTS

Cronbach's alpha values were 0.95 and 0.76 for the BPII 2.0 and Pedi-IKDC, respectively. There was no evidence of floor or ceiling effects for either the BPII 2.0 or the Pedi-IKDC. The Pearson r correlation coefficient between the BPII 2.0 and IKDC baseline scores taken at the initial consultation was 0.65 (P<0.001; 95% confidence interval, 0.94-0.97). The intraclass correlation coefficient (2,k) for the test-retest subsample (n=30) was 0.94. Patient interviews revealed that they thought the BPII 2.0 questions were both important and comprehensible.

CONCLUSIONS

The BPII 2.0 is a valid, reliable, and disease-specific patient-reported outcome measure that can be used with an adolescent population with lateral patellofemoral instability. The BPII 2.0 has demonstrated criterion validity through its moderately strong correlation to the Pedi-IKDC for adolescents.

Recurrent Patellofemoral Instability in the Pediatric Patient: Management and Pitfalls

PURPOSE OF REVIEW

The purpose of the review is to discuss the relevant pathoanatomy, management, complications, and technical considerations for recurrent patellofemoral instability (PFI) in the pediatric population. Special consideration is given to recent literature and management of the patient with repeat instability following surgery.

RECENT FINDINGS

Patellar stabilization surgery is in principle dependent upon restoration of normal patellofemoral anatomy and dynamic alignment. Historically, treatment options have been numerous and include extensor mechanism realignment, trochleoplasty, and more recently repair and/or reconstruction of the medial patellofemoral ligament (MPFL) as a dynamic check rein during initial knee flexion. In skeletally immature patients, preference is given to physeal-sparing soft tissue procedures. While medial patellofemoral ligament reconstruction has become a popular option, postoperative failure is a persistent issue with rates ranging from 5 to 30% for PFI surgery in general without any single procedure (e.g., distal realignment, MPFL reconstruction) demonstrating clear superiority. Failure of surgical patellar stabilization is broadly believed to occur for three main reasons: (1) technical failure of the primary stabilization method, (2) unaddressed static and dynamic pathoanatomy during the primary stabilization, and (3) intrinsic risk factors (e.g., collagen disorders, ligamentous laxity). PFI is a common orthopedic condition affecting the pediatric and adolescent population. Treatment of repeat instability following surgery in the PFI patient requires understanding and addressing underlying pathoanatomic risk factors as well as risks and reasons for failure.

Isolated trochleoplasty for recurrent patellar dislocation has lower outcome and higher residual instability compared with combined MPFL and trochleoplasty: a systematic review

PURPOSE

To identify the efficacy of isolated trochleoplasty (TP) as an independent treatment for severe trochlear dysplasia compared with TP combined with medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Search of current literature using terms (trochleoplasty and medial patellofemoral ligament reconstruction) in the electronic search engines PubMed and Embase, and Medline databases was performed on February 25, 2018, and it yielded 515 abstracts for review. At the end of the search, six articles met specific inclusion criteria and were included in this review. Means were calculated for population size, age and follow-up time. The Kujala score was analyzed as the primary clinical outcome parameter in the meta-analysis. Pooled estimates were calculated for postoperative complications.

RESULTS

Six studies with a total of 192 knees (168 patients) were included in this analysis. The isolated TP group comprised of 3 articles with a total of 111 knees, and the TP combined with MPFL group comprised of 3 articles with a total of 81 knees. At the final follow-up, the preoperative Kujala score increased significantly by 21.39 (95% CI 18.94, 23.84; P < 0.00001) points in the isolated TP group and by 24.91 (95% CI 15.47, 34.36; P < 0.00001) points in the TP combined with MPFL group. The rates of subjective patellar instability including subluxation and anterior knee pain were 1.03% and8.45% respectively. Meanwhile, the rate of objective patellar redislocation was 2.06% in isolated TP group and 0% in TP combined with MFPL group. A total of 8.24% returned to the operating room for additional procedures in the isolated TP group and 7.04% in the TP combined with MPFL group.

CONCLUSION

Trochleoplasty is a useful and reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. However, it as isolated treatment for patients has lower outcome and higher residual instability compared with combined MPFL and trochleoplasty.

Manipulation Under Anesthesia With Lysis of Adhesions Is Effective in Arthrofibrosis After Sulcus-Deepening Trochleoplasty: A Prospective Study

Background

Sulcus-deepening trochleoplasty has been established as an effective treatment for patellar instability due to trochlear dysplasia. However, arthrofibrosis is a known complication following trochleoplasty, which may require manipulation under anesthesia (MUA) with or without lysis of adhesions (LOA) to increase the knee range of motion (ROM), especially flexion.

Purpose

To prospectively follow patients for ROM improvements and subsequent complications after undergoing MUA with or without LOA in the setting of sulcus-deepening trochleoplasty.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 76 knees with severe trochlear dysplasia were prospectively enrolled and underwent sulcus-deepening trochleoplasty, with a mean (±SD) follow-up of 32.5 ± 19.3 months. Concomitant procedures included medial patellofemoral ligament reconstruction, lateral retinacular release, and tibial tubercle osteotomy. Physical examination including ROM and findings of recurrent patellar instability were collected for all patients. Arthrofibrosis was defined as active and passive flexion less than 90° within 3 months of surgery combined with a plateau in progress with physical therapy. Paired-samples and independent-samples t tests were used. A P value less than .05 was considered significant.

Results

A total of 62 knees met inclusion and exclusion criteria and were included in the study. Of these patients, 11 experienced arthrofibrosis as a complication and underwent MUA within 3 months of their index procedure. Of these 11 patients, 9 subsequently underwent arthroscopic LOA following MUA because acceptable ROM could not be achieved with manipulation alone. Patients with arthrofibrosis had a premanipulation mean ROM that was significantly different from those without arthrofibrosis (77.3° ±18.6° vs 133.3° ± 12.7°, respectively; P < .001). In the arthrofibrotic group, postoperative ROM increased significantly after MUA and/or LOA compared with the preoperative ROM (127.3° ± 12.5° vs 77.3° ± 18.6°, respectively; P < .001). ROM in the arthrofibrotic group after MUA/LOA was not significantly different from that in the nonarthrofibrotic group (flexion, 127.3° ± 12.5° vs 133.3° ± 12.7°, respectively; P = .156). No complications from the MUA or LOA were reported at subsequent follow-up visits.

Conclusion

When indicated in the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty is a treatment for disabling recurrent patellar instability with a known complication of arthrofibrosis. Initiation of postoperative physical therapy within 3 days of surgery may reduce the incidence of arthrofibrosis. If arthrofibrosis is encountered after a sulcus-deepening trochleoplasty, MUA without LOA is not as effective as when following other procedures of the knee, whereas MUA with LOA is an effective procedure likely to result in ROM and patient outcome scores similar to those of a nonarthrofibrotic knee after the same procedure. Both MUA and LOA appear to be safe based on the limited number of patients in this study without complication.

Trochleoplasty provides good clinical outcomes and an acceptable complication profile in both short and long-term follow-up

PURPOSE

The purpose of this study is to report on the global distribution and clinical outcomes of published articles related to trochleoplasty.

METHODS

The online databases OVID Medline, OVID EMBASE, and the Cochrane Library were searched for the literature assessing trochleoplasty performed for lateral patellofemoral instability (LPI). Study data were abstracted looking at global trends in the literature, as well as clinical and patient-reported outcomes following this technique.

RESULTS

For the assessment of global distribution, 29 studies including 998 patients met the inclusion criteria. The majority of the studies were conducted in Europe (93%) and most used an open thin flap technique (52%). For the secondary analysis of clinical outcomes, 21 studies were included with significant heterogeneity in patient selection, reporting on the degree of trochlear dysplasia, and patient-reported outcomes. All trochleoplasty techniques showed statistically significant improvement in clinical outcomes at average 50 months (range 3-228 months) post-operative, with most patients being satisfied with their procedure. Re-dislocation and complication rates were low.

CONCLUSIONS

European centers have published majority of data on trochleoplasty surgery, which has been shown to be an acceptable procedure for patients with high-grade trochlear dysplasia and LPI. Trochleoplasty has demonstrated good clinical outcomes, a low re-dislocation rate, and an acceptable complication profile in both short and long-term follow-up. This study highlights the difficulty in reporting outcomes in this group of patients due to heterogeneity in patient selection, grading of trochlear dysplasia, and the lack of disease-specific outcome measures.

LEVEL OF EVIDENCE

IV.

Trochleoplasty, Medial Patellofemoral Ligament Reconstruction, and Open Lateral Lengthening for Patellar Instability in the Setting of High-Grade Trochlear Dysplasia

Trochlear dysplasia is the most commonly encountered pathoanatomy in patients who present with patellar instability. Outcomes of trochleoplasty procedures have shown low rates of recurrent instability and high patient-reported outcome scores. This article describes a "thin-flap" groove-deepening trochleoplasty combined with medial patellofemoral ligament reconstruction with a gracilis allograft and lateral retinacular lengthening to treat recurrent patellar instability due to high-grade trochlear dysplasia. This technique can obviate tibial tubercle osteotomy by normalizing the position of the trochlear groove and, subsequently, decreasing the tibial tubercle-to-trochlear groove distance.

Surgical management of patellofemoral instability part 2: post-operative imaging

The patellofemoral joint is a complex joint requiring contributions from both bone and soft tissue for its stability. Pathology of the patellofemoral joint manifests as instability or anterior knee pain. Careful clinical and imaging assessment is important for managing these patients with cross-sectional imaging being a vital component in pre-surgical planning. Operative treatment can involve soft tissue procedures, bony procedures or both. The purpose of part 2 of this two-part article is to review the post-operative imaging findings of the knee extensor mechanism. In doing so, we will provide an overview of some of the bony and soft tissue procedures performed with details of their indications and possible complications. An appreciation of the post-operative surgical appearances will ensure a more comprehensive report and can prevent misinterpretation by the radiologist.

Patient-Reported Outcome Measures for Patellofemoral Instability: a Critical Review

PURPOSE OF REVIEW

The purpose of this paper was to review the current psychometric properties of patient-reported outcome measures that are commonly used for patients with patellofemoral instability. This review provides evidence to guide the selection of subjective outcome measures for assessing outcomes in clinical care and research studies.

RECENT FINDINGS

At the present time, there are two patient-reported outcome measures that have been designed for, and tested on, large cohorts of patellofemoral instability patients, the Banff Patella Instability Instrument (BPII) and the Norwich Patellar Instability Score (NPI). The BPII is a wholistic quality of life outcome measure and the NPI is a symptom score. The use of disease-specific outcome measures such as the BPII and NPI, in combination with generic knee, functional activity, and/or psychological outcome measures that have been proven to be valid and reliable for the patellofemoral instability population, is most likely to provide a well-rounded evaluation of treatment outcomes.

Research Methods and Progress of Patellofemoral Joint Kinematics: A Review

Patellofemoral pain syndrome has a high morbidity, and its pathology is closely associated with patellofemoral joint kinematics. A series of in vivo and in vitro studies have been conducted to explore patellofemoral kinematics, and the findings are relevant to the diagnosis, classification, and management of patellofemoral diseases and even the whole knee joint. However, no definite conclusion on normal patellofemoral kinematics has been established. In this study, the measurement methodologies of patellofemoral kinematics (including data collection methods, loading conditions, and coordinate system) as well as their advantages and limitations were reviewed. Motion characteristics of the patella were analyzed. During knee flexion, the patellar flexion angle lagged by 30–40% compared to the tibiofemoral joint flexion. The patella tilts, rotates, and shifts medially in the initial stage of knee flexion and subsequently tilts, rotates, and shifts laterally. The finite patellar helical axis fluctuates near the femoral transepicondylar axis or posterior condylar axis. Moreover, factors affecting kinematics, such as morphology of the trochlear groove, soft tissue balance, and tibiofemoral motion, were analyzed. At the initial period of flexion, soft tissues play a vital role in adjusting patellar tracking, and during further flexion, the status of the patella is determined by the morphology of the trochlear groove and patellar facet. Our findings could increase our understanding of patellofemoral kinematics and can help to guide the operation plan for patients with patellofemoral pain syndrome.

Trochlear Dysplasia and Its Relationship to the Anterior Distal Femoral Physis

BACKGROUND

Trochlear dysplasia is a known risk factor for patellar instability in adolescent patients. A spatial relationship between dysplastic trochlea and anterior distal femoral physis has not been established. The purpose of this study was to investigate this relationship. Our hypothesis was that the position of the dysplastic trochlea and trochlear bump would coincide with the anterior distal femoral physis and that the distance between them would increase with age.

METHODS

In a retrospective study, magnetic resonance images of adolescents with trochlear dysplasia were evaluated. Measurements performed included trochlear depth, trochlear bump size, proximal trochlea-physis distance, and trochlear bump-physis distance. Linear regression analyses were performed to correlate the variables with increasing age.

RESULTS

In total, 175 knees (160 patients) with trochlear dysplasia were included. The mean trochlea-physis distance was 4.50 mm (SD=1.93) and it increased with age (slope=0.26; P<0.01). The lateral aspect of trochlea was proximal to the physis in 24 (13.7%) knees and was at the level of the physis in 31 (17.7%) knees. The size of trochlear bump increased with age (slope=0.15; P=0.01). The bump-physis distance increased with age (slope=0.41; P<0.01).

CONCLUSIONS

The dysplastic trochlea is closely related to the anterior distal femoral physis. The distance between the dysplastic trochlea and femoral physis increases with age. The close relationship between proximal aspect of trochlea and anterior distal femoral physis should be considered when trochlear surgery is planned in skeletally immature patients.

LEVEL OF EVIDENCE

Level II.

Anteromedial Tibial Tubercle Osteotomy Improves Results of Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability in Patients With Tibial Tuberosity-Trochlear Groove Distance of 17 to 20 mm

PURPOSE

To compare the midterm clinical outcomes of anteromedialization tibial tubercle osteotomy combined with medial patellofemoral ligament reconstruction (TTO+MPFLR) with MPFLR alone (MPFLRa) for the treatment of recurrent patellar instability (RPI) in patients with a tibial tuberosity-trochlear groove (TT-TG) of 17 to 20 mm.

METHODS

From January 2008 to August 2013, patients with RPI and a TT-TG of 17 to 20 mm were divided into 2 groups: TTO+MPFLR or MPFLRa. Subjects were evaluated for J sign classification (1-4+); patellar glide (1-4+); the apprehension test; increased femoral anteversion; the Caton index; trochlear dysplasia; TT-TG; and Kujala, Lysholm, International Knee Documentation Committee (IKDC), and Tegner scores. Kujala improvement was the primary outcome.

RESULTS

Forty-two subjects were evaluated, 18 in the TTO+MPFLR group and 24 in the MPFLRa group. Mean follow-up time was 40.86 months (range, 24-60 months). Demographics between the groups were not different. Preoperatively, there was no statistically significant difference between groups regarding J sign classification; patellar glide; the apprehension test; increased femoral anteversion; the Caton index; trochlear dysplasia; TT-TG; and Kujala, Lysholm, IKDC, and Tegner scores. Postoperative J sign classification mean results comparing TTO+MPFLR and MPFLRa, respectively, were 1 and 1.33 (P = .006). Improvement was significantly higher in the TTO+MPFLR group in all scores except for Tegner. Kujala improvement, 30.27 and 23.95, respectively (P = .003), was also clinically significant, favoring TTO+MPFLR. Lysholm improvement was 40.5 and 36.2, respectively (P = .02), and IKDC improvement was 38.59 and 31.6, respectively (P = .002). There were no reported recurrent subluxations or dislocations in either group.

CONCLUSIONS

TTO+MPFLR resulted in better functional outcome scores and patellar kinematics compared with MPFLRa in the surgical treatment of RPI in patients with a TT-TG distance of 17 to 20 mm.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

No Growth Disturbance After Trochleoplasty for Recurrent Patellar Dislocation in Adolescents With Open Growth Plates

BACKGROUND

Trochlear dysplasia is the most important risk factor for patellofemoral instability among adolescents; therefore, trochleoplasty to reshape the trochlear groove is the treatment of choice for patients with high-grade trochlear dysplasia. However, in the presence of open growth plates, there is a potential risk of injury to the distal femoral growth plate and subsequent growth disturbance. As such, most authors do not recommend trochleoplasty for skeletally immature patients. The effect of trochleoplasty on femoral growth when performed before closure of the distal femoral physis remains unclear.

HYPOTHESIS

For patients with open growth plates and an expected growth <2 years, trochleoplasty does not cause growth disturbance of the distal femur.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Eighteen consecutive adolescents (18 knees) with open physes and severe trochlear dysplasia underwent thin flap trochleoplasty. Pre- and postoperative radiographic examination included anteroposterior and lateral views to assess leg axis and patella alta. A preoperative radiograph of the left hand was performed to measure skeletal age. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and tibial tubercle-trochlear groove distance. Evaluation included pre- and postoperative physical examination with evaluation of leg length and leg axis, Kujala score, and Tegner activity score.

RESULTS

The median age at the time of operation was 12.6 years (range, 12.2-13.3 years) for girls and 14.5 years (14.0-15.4 years) for boys. The mean follow-up after operation was 2.3 years after surgery (range, 2.0-3.0 years). At follow-up for all patients, the growth plates of the knee were closed. Impairment of growth of the distal femur was found neither clinically nor radiographically. No recurrent dislocation occurred. The median Kujala score improved significantly from 67 (range, 54-75) preoperatively to 89.5 (range, 78-96) at follow-up ( P < .01). The median visual analog scale showed significant pre- to postoperative improvement from 5 (range, 3-7) to 1 (range, 0-3) ( P < .01). The activity level according to the Tegner activity score did not change significantly.

CONCLUSION

In this study, trochleoplasty as a treatment for patellofemoral instability of patients with open physes and an expected growth of not more than 2 years showed good clinical results without redislocation and with no growth disturbance. Therefore, for selected adolescent patients with high-grade trochlear dysplasia, trochleoplasty can be safely performed up to 2 years before the projected end of growth.

Patellar Instability Management: A Survey of the International Patellofemoral Study Group

BACKGROUND

Although patellofemoral instability is among the most prevalent knee disorders, the management of patients with this condition is complex and remains variable, given the lack of long-term, high-level clinical outcome studies to compare various operative and nonoperative modalities.

PURPOSE

To discover a consensus within treatment controversies in patellofemoral instability among experienced knee surgeons with a specific interest in the patellofemoral joint.

STUDY DESIGN

Expert opinion; Level of evidence, 5.

METHODS

A 3-step modified Delphi technique was used to establish a consensus. A 34-question, case-based online survey regarding patellofemoral instability was distributed to all active members of the International Patellofemoral Study Group. Consensus statements were generated if at least 66% of the respondents agreed and then redistributed to the same panel. Modifications to the consensus statements were made based on the iterative feedback process until no discordance was encountered in the third stage.

RESULTS

Eight consensus statements were achieved. Nonoperative management is the current standard of care for a first-time dislocation in the absence of an osteochondral fragment or loose body requiring excision (100% agreement). In patients with a first-time dislocation with an operative osteochondral fracture requiring excision or repair, patellar instability should be addressed concurrently (89% agreement). Recurrent instability should be treated surgically, with most surgeons favoring medial reconstruction (77%-86% agreement). While there is general agreement that bony procedures should be performed to correct underlying bony deformities, there is no consensus regarding the most appropriate type of procedure performed. Lateral release should not be performed in isolation for the treatment of patellar instability (89% agreement).

CONCLUSION

Despite the consensus generated in this study, our current understanding remains limited by a lack of high-level evidence as well as the numerous complex variables influencing treatment decision making. High-quality, multicenter randomized controlled trials, particularly those directly comparing specific surgical treatment methods while controlling for underlying risk factors, are needed to address these areas of uncertainty.

Evaluation of Trochlear Dysplasia Severity Using Trochlear Angle: A Retrospective Study Based on Computed Tomography (CT) Scans

Background

Trochlear dysplasia is an important pathological factor in patellofemoral instability. Quantitative evaluation of the severity of trochlear dysplasia is rare and remains unclear.

Material/Methods

Computed tomography (CT) data on 136 knees (95 patients) with trochlear dysplasia in the case group and an age- and sex-matched cohort of 120 knees (70 patients) in the control group were collected for this retrospective study. All participants had undergone CT scans in the supine position. The trochlear angles (TA) formed by the posterior condylar line and the trochlear line were calculated and compared. The threshold for statistical significance was set at p<0.05.

Results

The mean TA values were significantly greater in the case group compared to the control group independent of sex (p<0.01). The distribution of trochlear dysplasia of Dejour grades was type A n=34, type B n=31, type C n=40, and type D n=31. Except for types A and B, differences in the trochlear dysplasia grade between any 2 other types were statistically significant (p<0.01).

Conclusions

The technique of measuring TA is reproducible and accurate in patients with patellar instability and normal controls. The TA positively correlates with higher levels of trochlear dysplasia. This technique can help to evaluate and treat trochlear dysplasia in research as well as in clinical practice.

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.

Solitary Trochleoplasty for Treatment of Recurrent Patellar Dislocation

Background

Solitary trochleoplasty for recurrent patellar dislocation offers a unique benefit in that it addresses the most important factor in patellar instability: the trochlear dysplasia.

Description

The trochlea is visualized through a lateral arthrotomy of the knee joint. An osteochondral layer is peeled off with curved chisels and extended into the intercondylar notch. A triangular bone block is removed from the subchondral bone to form the new groove. A new groove is begun with a chisel and smoothed with a high-speed burr. Also, the osteochondral layer is thinned out and fixed back transosseously in the new groove with 2 Vicryl (polyglactin) bands. The bone block is used to lengthen the lateral condyle by placing it under the osteochondral layer at the proximal extension of the lateral femoral condyle with an overlap of 1 cm.

Alternatives

Nonsurgical alternatives include a knee or patellar brace, taping of the patella, and physiotherapy for strengthening of the vastus medialis obliquus of the quadriceps muscle. Surgical alternatives include reconstruction of the medial patellofemoral ligament; several femoral and tibial osteotomies, such as rotational osteotomies of the femur and tibia or medialization of the tibial tuberosity; and several soft-tissue interventions, such as medial reefing, relocation of the patellar tendon as described by Goldthwait¹, and proximal realignments according to the method described by Insall et al.² or Green et al.³.

Rationale

Most patients with recurrent patellar dislocation have a dysplastic trochlea⁴, which is considered to be the primary reason for a recurrence. While interventions such as reconstruction of the medial patellofemoral ligament or femoral and tibial osteotomies also provide stability of the patella, they do not change the most essential factor of the instability-the trochlear dysplasia. The trochleoplasty addresses this underlying condition and reshapes the trochlea.

Patellar Instability: When is Trochleoplasty Necessary?

Trochleoplasty is a very effective procedure for correcting trochlear dysplasia and addressing instability of the patella. With an increasing knowledge about the anatomy and biomechanics of the anterior distal femur, a wider array of surgical techniques may be applied to address specific conditions. Patients must be carefully selected to undergo trochleoplasty by use of a thorough history and physical examination as well as basic and advanced imaging. The presence of a "J sign" on physical examination, a history of recurrent instability, patella alta, trochlear dysplasia, and elevated tibial tubercle to trochlear groove are signs and symptoms for which the patient should be evaluated. We attempt to elucidate when trochleoplasty is indicated by means of addressing all aspects of evaluation.

Avoiding Complications with MPFL Reconstruction

PURPOSE OF REVIEW

To discuss the potentially significant complications associated with medial patellofemoral ligament (MPFL) reconstruction. Additionally, to review the most current and relevant literature with an emphasis on avoiding these potential complications.

RECENT FINDINGS

Multiple cadaveric studies have characterized the anatomy of the MPFL and the related morphologic abnormalities that contribute to recurrent lateral patellar instability. Such abnormalities include patella alta, excessive tibial tubercle to trochlear grove (TT-TG) distance, trochlear dysplasia, and malalignment. Recent studies have evaluated the clinical outcomes associated with the treatment of concomitant pathology in combination with MPFL reconstruction, which is critical in avoiding recurrent instability and complications. Although there remains a lack of consensus regarding various critical aspects of MPFL reconstruction, certain concepts remain imperative. Our preferred methods and rationales for surgical techniques are described. These include appropriate work up, a combination of procedures to address abnormal morphology, anatomical femoral insertion, safe and secure patellar fixation, appropriate graft length fixation, and thoughtful knee flexion during fixation.

Impact of broad regulatory regions on Gdf5 expression and function in knee development and susceptibility to osteoarthritis

OBJECTIVES

Given the role of growth and differentiation factor 5 (GDF5) in knee development and osteoarthritis risk, we sought to characterise knee defects resulting from Gdf5 loss of function and how its regulatory regions control knee formation and morphology.

METHODS

The brachypodism (bp) mouse line, which harbours an inactivating mutation in Gdf5, was used to survey how Gdf5 loss of function impacts knee morphology, while two transgenic Gdf5 reporter bacterial artificial chromosome mouse lines were used to assess the spatiotemporal activity and function of Gdf5 regulatory sequences in the context of clinically relevant knee anatomical features.

RESULTS

Knees from homozygous bp mice (bp/bp) exhibit underdeveloped femoral condyles and tibial plateaus, no cruciate ligaments, and poorly developed menisci. Secondary ossification is also delayed in the distal femur and proximal tibia. bp/bp mice have significantly narrower femoral condyles, femoral notches and tibial plateaus, and curvier medial femoral condyles, shallower trochlea, steeper lateral tibial slopes and smaller tibial spines. Regulatory sequences upstream from Gdf5 were weakly active in the prenatal knee, while downstream regulatory sequences were active throughout life. Importantly, downstream but not upstream Gdf5 regulatory sequences fully restored all the key morphological features disrupted in the bp/bp mice.

CONCLUSIONS

Knee morphology is profoundly affected by Gdf5 absence, and downstream regulatory sequences mediate its effects by controlling Gdf5 expression in knee tissues. This downstream region contains numerous enhancers harbouring human variants that span the osteoarthritis association interval. We posit that subtle alterations to morphology driven by changes in downstream regulatory sequence underlie this locus' role in osteoarthritis risk.

Trochleoplasty procedures show complication rates similar to other patellar-stabilizing procedures

PURPOSE

Trochleoplasty aims to restore patellar stability. Various techniques have been described and almost all authors report successful results. However, the procedure has a significant risk of complications. Purpose of this study was to perform a systematic review and meta-analysis of the available literature to assess the rate of complications after the various techniques used for trochleoplasty procedures.

MATERIALS AND METHODS

MEDLINE, EMBASE, Web of Science and Cochrane Library databases were searched. Studies on patients with recurrent patellar instability treated with a trochleoplasty with or without additional procedure, and reported complications were included. The primary outcome was the rate of complications per technique. A meta-analysis was performed whenever three or more studies per surgical technique could be included.

RESULTS

The selection process resulted in 20 studies included for analysis. A lateral facet elevating trochlear osteotomy was reported by two studies, ten studies reported on a Bereiter trochleoplasty, five on a Dejour trochleoplasty, one on an arthroscopic technique, one on a 'modified' technique and one on a recession wedge trochleoplasty. Meta-analysis showed that proportion of recurrent dislocation was 0.04 (95% CI 0.02-0.07) for Bereiter trochleoplasty and 0.02 (95% CI 0-0.08) for Dejour trochleoplasty. These proportions were 0.06 (95% CI 0.02-0.13) and 0.09 (95% CI 0.03-0.27) for recurrent instability, 0.07 (95% CI 0.02-0.19) and 0.12 (95% CI 0.00-0.91) for patellofemoral osteoarthritis and 0.08 (95% CI 0.04-0.14) and 0.20 (95% CI 0.11-0.32) for further surgery respectively.

CONCLUSION

This study demonstrates that the complications after a Bereiter and Dejour trochleoplasty including additional procedures are in the range of those of other patellar stabilizing procedures. For four other techniques, no meta-analysis could be performed. The clinical relevance of this study is that it provides clinicians with the best currently available evidence on the rate of complications after trochleoplasty procedures. This can be helpful in the process of deciding whether or not to perform such a procedure, and can be used to better inform patients about the advantages and disadvantages of different trochleoplasty procedures.

LEVEL OF EVIDENCE

Level IV.

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.

Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and meta-analysis

PURPOSE

Many studies have reported satisfactory clinical outcomes and low redislocation rates after reconstruction of the medial patellofemoral ligament (MPFL) for the treatment of lateral patellar instability. Despite uncorrected severe trochlear dysplasia (Dejour type B to D) being acknowledged as a major reason for less favourable clinical outcomes and a higher incidence of patellar redislocations after an isolated MPFL reconstruction, the evidence for a deepening trochleoplasty procedure remains scarce in the current literature. The hypothesis of this systematic review and meta-analysis was that a deepening trochleoplasty in combination with an a la carte extensor apparatus balancing procedure provides lower redislocation rates and superior clinical outcomes than isolated MPFL reconstruction in patients with lateral patellar instability caused by severe trochlear dysplasia.

METHODS

A systematic review of the literature was conducted using specific inclusion and exclusion criteria for clinical studies reporting index operations (trochleoplasty and MPFL reconstruction) for the treatment of patellar instability caused by severe trochlear dysplasia. The Kujala score was analysed as the primary clinical outcome parameter in a random effects meta-analysis.

RESULTS

Ten uncontrolled studies with a total of 407 knees (374 patients) were included in this analysis. The MPFL group comprised 4 studies with a total of 221 knees (210 patients), and the trochleoplasty group comprised 6 studies with a total of 186 knees (164 patients). The mean preoperative Kujala score ranged between 50.4 and 70.5 in the MPFL group and between 44.8 and 75.1 in the trochleoplasty group. The pooled Kujala score increased significantly by 26.4 (95% CI 21.4, 31.3; P < 0.00001) points in the MPFL group and by 26.2 (95% CI 19.8, 32.7; P < 0.00001) points in the trochleoplasty group. The post-operative patellar redislocation/subluxation rate was 7% in the MPFL group and 2.1% in the trochleoplasty group.

CONCLUSION

This analysis found significant post-operative improvements in patient-reported outcomes for patients undergoing both an MPFL reconstruction and in those undergoing a trochleoplasty plus an individual extensor apparatus balancing procedure when assessed using the Kujala score. The likelihood of preventing the patella from subsequent post-operative redislocation/subluxation was, however, greater in patients who underwent trochleoplasty plus extensor balancing.

LEVEL OF EVIDENCE

IV.

Increased Magnetic Resonance Imaging Signal of the Lateral Patellar Facet Cartilage: A Functional Marker for Patellar Instability?

BACKGROUND

In the knee joint, predisposition for patellar instability can be assessed by an abnormal Insall-Salvati index, tibial tuberosity-trochlear groove (TTTG) distance, and abnormal shape of patella and trochlea. Given the complex anatomic features of the knee joint with varying positions of the patella during motion, the presence of a single or even a combination of these factors does not inevitably result in patellar instability. After trocheoplasty in patients with trochlear dysplasia, assessment of trochlear cartilage and subchondral bone is limited due to postoperative artifacts. Identification of presence of edema in the patellar cartilage may be helpful to identify patellar instability before and after surgery in these patients.

PURPOSE

To determine whether increased signal intensity of the lateral patellar facet cartilage or measurements of abnormal patellofemoral articulation are associated with patellar instability before and after trochleoplasty.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-two patients with clinical diagnosis of patellar instability who underwent trochleoplasty, with magnetic resonance imaging (MRI) of the knee before and after surgery, were identified. The following observations and measurements were obtained in preoperative imaging: Insall-Salvati ratio, tibial tuberosity-trochlear groove (TTTG) distance, patellar shape (Wiberg), trochlear shape (Hepp), and edema in the lateral patellar facet cartilage. At 3 to 12 months after surgery, the presence or absence of edema in the cartilage of the lateral facet of the patella, the trochlear shape, and TTTG distance were reassessed. Wilcoxon matched-pairs signed rank test and Student t test were used. Interreader agreement was calculated as the Cohen κ or paired Student t test.

RESULTS

Increased cartilage signal was present in 20 patients before trochleoplasty and in 4 after trochleoplasty. Insall-Salvati ratio was greater than 1.20 in 20 patients. Patellar shape was greater than type 2 in 18 patients. Trochlear shape was greater than type 2 in 21 patients before and 7 after trochleoplasty. Mean TTTG distance was 14 mm before and 10 mm after surgery. When results before and after surgery were compared, a significant difference was found for cartilage signal, TTTG distance, and trochlear shape. Agreement for observations was moderate to substantial, and no significant differences were found for interreader agreement ( P > .05).

CONCLUSION

Patellar cartilage at the lateral facet of the patella can be assessed after trochleoplasty despite postoperative artifacts in the trochlea. A decrease of patellar edema seems to be associated with improved femoropatellar articulation. Moreover, patellar edema may be used as a functional criterion of patellofemoral instability. This would provide additional information compared to morphologic criteria which just describe predisposing factors for femoropatellar instability.