Current practice trends in the surgical management of patellofemoral instability: a survey of the Paediatric Research in Sports Medicine (PRiSM) Society

Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients: A Systematic Review of Outcomes by Fixation Technique

Background

Various medial patellofemoral ligament (MPFL) reconstruction techniques have been developed to minimize risks to the physis in skeletally immature patients.

Purpose

To examine outcomes of MPFL reconstruction (MPFLR) based on fixation technique in skeletally immature patients.

Study Design

Systematic review; Level of evidence, 4.

Methods

PubMed, Scopus, Ovid, Cochrane Library, and CINAHL databases were searched for the literature on outcomes of MPFLR in the pediatric population, utilizing various anatomic and nonanatomic techniques. Primary outcomes were postoperative redislocation rates, return-to-sports (RTS) rates, and patient-reported outcomes (PROs). Moreover, outcomes involving sequela of growth plate disturbance were collected.

Results

The final analysis included 17 studies-2 using sling-based techniques, 3 using surface-based techniques, 5 using soft tissue realignments, and 7 utilizing transosseous femoral fixations. Higher rates of postoperative redislocation were found in the sling-based (14.8%) and distal soft tissue realignment using semitendinosus tenodesis (38%) techniques, while lower rates were noted with surface-based (1.3%) and transosseous (3.4%) techniques. For PROs, there were large amounts of heterogeneity among studies, but all reported postoperative improvements, with more positive PROs generally seen in anatomic reconstructions. The RTS rate was 100% for surface-based techniques, 79.4% for distal soft tissue realignments, 79.5% for soft tissue realignment techniques, and 83.2% for transosseous techniques. No negative outcomes as a sequela of growth plate disturbance were reported.

Conclusion

Nonanatomic techniques-such as sling-based and distal soft tissue realignment techniques-have higher rates of redislocation and lower RTS rates in skeletally immature patients undergoing MPFLR. Surface-based and transosseous tunnel-based techniques were shown to have lower redislocation and higher RTS rates.

Clinical Relevance

This review provides insight into the most appropriate surgical management of patellar instability in patients with open growth plates.

Isokinetic Strength Profiles Among Youth after Medial Patellofemoral Ligament Reconstruction

Background

Knee strength is a critical measure of successful rehabilitation following medial patellofemoral ligament reconstruction (MPFLR). Yet, strength outcomes of youth following MPFLR are not widely reported.

Hypothesis/Purpose

The primary purpose was to profile isokinetic strength outcomes by sex and age among youth following MPFLR. A secondary purpose was to determine the relationship between normalized isokinetic strength values and patient-reported outcome scores by age and sex. The hypotheses were that 1) males would demonstrate higher normalized strength, and that 2) a higher proportion of males would achieve ≥90% limb symmetry when compared to females.

Study Design

Cross-sectional.

Methods

At 6.9±2.1 months after MPFLR, 162 patients completed isokinetic assessment of knee extension (KE) and flexion (KF) strength at 180°/s and 300°/s on both limbs (uninvolved [UN], involved [INV]). Strength data and patient-reported outcome scores, including the International Knee Documentation Committee (IKDC) Subjective Knee Form and Pediatric Quality of Life Inventory (PedsQL) were extracted from electronic medical records. Descriptive statistics were used to categorize data by age (Pre-adolescent, Early Adolescent, Late Adolescent, Young Adult) and sex. Independent-samples t-tests and chi-square analyses were used to determine sex-based differences in strength. Multiple linear regression analyses were used to determine the relationship between strength and patient-reported function.

Results

Among Early Adolescents, males demonstrated higher normalized KE strength at 300°/s compared to females (UN: 1.27±0.3 vs. 1.07±0.3 [p=0.01]; INV: 1.07±0.2 vs. 0.92±0.3 [p=0.03]). Among Late Adolescents, males demonstrated higher INV limb strength for KE 180°/s (1.55±0.53 vs. 1.24±0.5; p=0.02), KE 300°/s (1.25±0.4 vs. 1.00±0.4; p=0.01), and KF 180°/s (0.98±0.4 vs. 0.82±0.3; p=0.05). A higher proportion of Late Adolescent and Young Adult males achieved ≥90% LSI compared to females (p=<0.01-0.04). Regression models estimating IKDC and PedsQL scores were significant with INV KE strength as an independent variable (p=0.01-0.03).

Conclusions

Males demonstrated higher normalized strength and symmetry compared to females following MPFLR. Higher INV KE strength was associated with higher patient-reported function.

Level of Evidence

2b.

Three different patellar fixation techniques yield similar clinical and radiological outcomes in recurrent patellar dislocation undergoing medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to evaluate and compare the clinical and radiological outcomes of three different patellar fixation techniques on medial patellofemoral ligament reconstruction (MPFLR) in the treatment of patellar dislocation (PD).

METHODS

Between 2015 and 2020, 130 patients with recurrent PD who underwent surgical reconstruction were eligible for this retrospective study: 48 patients were treated with the semi-tunnel bone bridge fixation technique (Group A), 42 patients were treated with the suture anchor fixation technique (Group B) and 40 patients were treated with the transpatellar tunnel fixation technique (Group C). Clinical outcomes included functional outcomes (Kujala, Lysholm and International Knee Documentation Committee scores), activity levels (Tegner activity score and return to sports), physical examinations, patellar re-dislocation rate and complications. Radiological outcomes included patellar congruence angle, patellar tilt angle, lateral patellar translation and lateral patellar angle.

RESULTS

All clinical and radiological outcomes improved significantly in all groups, without any significant difference among these three groups. At the final follow-up, no re-dislocation occurred, and all groups achieved a successful return to sports. However, the semi-tunnel bone bridge and suture anchor fixation techniques showed statistically higher Tegner activity scores (p = 0.004) and shorter time from surgery to return to sports (p = 0.007) than the transpatellar tunnel fixation technique.

CONCLUSION

The three MPFLR patellar fixation techniques achieved favourable and comparable clinical and radiological outcomes in the treatment of PD. Compared with the transpatellar tunnel fixation technique, the semi-tunnel bone bridge and suture anchor fixation techniques may be more effective with higher activity levels.

LEVEL OF EVIDENCE

Level III.

The Number of Patellar Dislocation Events Is Associated With Increased Chondral Damage of the Trochlea

BACKGROUND

Patellofemoral instability is associated with chondral injuries to the patella, trochlea, and lateral femoral condyle. Although studies have demonstrated an association between patellar dislocations and chondral injuries, the influence of the number of dislocations on chondrosis is not established.

PURPOSE

To elucidate the precise association between the number of patellar dislocation events and the severity of chondral injuries in a multicenter cohort study at the time of patellar stabilization procedures.

STUDY DESIGN

Cross-sectional study; Level of evidence, 2.

METHODS

A prospective multicenter cohort study (JUPITER [Justifying Patellar Instability Treatment by Early Results]) database was queried for cases of primary patellofemoral instability procedures from December 2016 to September 2022. Cartilage lesions were classified using the International Cartilage Repair Society (ICRS) classification system during an arthroscopic or open evaluation (direct visualization), with grades 2 to 4 considered abnormal. The number of dislocations was categorized as 1, 2-5, and >5. Categorical variables were compared with the chi-square test, and binary logistic regression was performed to identify predictors of the presence of chondral lesions.

RESULTS

A total of 938 knees (mean age, 16.2 ± 3.8 years; 61.4% female) were included, with 580 (61.8%) demonstrating a chondral injury. The most affected region was the patella (n = 498 [53.1%]), followed by the lateral femoral condyle (n = 117 [12.5%]) and trochlea (n = 109 [11.6%]). There were no differences in the presence (P = .17) or grade (P = .63) of patellar lesions by the number of dislocations. Patients with >5 dislocations more frequently had trochlear chondral lesions (19.8%) compared with those with fewer dislocations (1, 7.6%; 2-5, 11.0%; P < .001). More dislocations were also associated with a higher proportion of ICRS grade 2 to 4 trochlear lesions (>5, 15.3%; 2-5, 10.0%; 1, 6.9%; P = .015). Combined patellar and trochlear lesions were also more common in those with >5 dislocations (P = .001). In multivariable regression, >5 dislocations was the only variable predictive of a trochlear lesion (odds ratio, 3.03 [95% CI, 1.65-5.58]; P < .001).

CONCLUSION

This large prospective cohort study demonstrated that recurrent patellar dislocations can lead to more severe chondral damage in specific locations in the knee. More than 5 dislocations was associated with a >3-fold increase in the incidence and severity of trochlear chondral injuries. There were no differences in the presence or grade of patellar lesions by the number of dislocations. These findings should caution surgeons regarding prolonged nonoperative treatment.

The Joystick Method: A Mini Open Technique for Repairing Patellar Osteochondral Fractures With Concomitant Medial Patellofemoral Ligament Reconstruction

Fixation of osteochondral fractures after patellar dislocation is typically done using an open approach due to the location of the defect. This is traditionally performed through a medial parapatellar arthrotomy to allow adequate visualization. By using the joystick method, adequate visualization is achieved with a smaller arthrotomy. Careful placement of the joystick in the planned anchor site of the medial patellofemoral ligament reconstruction reduces the number of drill sites in the patella.

Surgical techniques for medial Patellofemoral ligament reconstruction: a systematic review and meta-analysis of level I and II studies

PURPOSE

To determine the most optimal surgical technique for medial patellofemoral ligament reconstruction (MPFLR).

METHODS

Three databases MEDLINE, PubMed, and EMBASE were searched from inception to December 13th, 2022, for level I or II studies comparing MPFLR techniques. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on patient-reported outcome measures were recorded. Quality assessment was carried out using the MINORS and Cochrane Risk of Bias assessment tools. Certainty of evidence was carried out with the GRADE assessment tool.

RESULTS

Ten studies comprising 723 patients (723 knees) were included in this review. The weighted mean difference in Kujala, Lysholm, and IKDC scores comparing single- and double-tunnel patellar drilling techniques was 2.66 (95% CI -1.05-6.37, p = 0.16, I2 = 0%) with moderate certainty, 0.78 (95% CI -9.02-10.58, p = 0.88, I2 = 87%) with low certainty, and 1.71 (95% CI -2.43-5.86, p = 0.42, I2 = 0%) with low certainty, respectively. Double-suture anchor patellar fixation demonstrated greater Kujala scores than transpatellar fixation (87.1 ± 2.8 vs 84.0 ± 3.8, p < 0.001) with moderate certainty. Y-shaped graft patellar fixation demonstrated superior Kujala scores to C-shaped graft patellar fixation (95.9 ± 4.7 vs 91.3 ± 9.7, p = 0.001) with moderate certainty. Augmentation of femoral fixation with polyester sutures demonstrated superior Kujala scores (97.8 ± 6.4. vs 88.0 ± 6.3, p < 0.005) with low certainty. Four-stranded grafts demonstrated greater Kujala scores than two-stranded grafts (93.5 ± 2.6 vs 91.6 ± 3.5, p = 0.01) with low certainty.

CONCLUSION

The optimal MPFLR surgical technique is likely to utilize a four-stranded graft using either endobutton, double-suture anchor, or transosseous suture patellar fixation with polyester suture augmented interference screw femoral fixation. Orthopedic surgeons can consider employing such a technique to improve patient outcomes by conferring greater graft stability, strength, and function. Level of evidence Level II.