Persistent J-Sign Following Distalization with Correction of Patellar Height: A Descriptive study reviewing anatomic factors (195)

Objectives: The anatomic factors associated with a J-sign (patella dislocation in extension) are debated and likely multi-factorial. With trochlear shape and patella height playing a role. The goal of distalization of the tibial tubercle (dTTO) is normalization of patella height to improve patellar stabilization by earlier trochlear groove engagement. dTTO is felt to diminish or remove the J-sign by ‘by-passing’ the supra-trochlear bump, thus avoiding the need for a trochleoplasty in addition to a dTTO. The objective is to determine if a persistent J-sign after surgical patellar stabilization and adequate patellar height restoration is due to additional anatomic variances that were not surgically addressed. Methods: A retrospective chart review of 89 consecutive patients who were treated by a single surgeon for recurrent lateral patella dislocation with medial patellofemoral ligament reconstruction (MPFL-R) and dTTO was undertaken. 63 patients were identified with a pre-operative J-sign and formed the study sample. 40 of these patients had no J-sign post-operatively and 23 patients had a persistent postoperative J-sign. All patients had radiographic measurements made for patella alta (caton-deschamps index [CD]), and magnetic resonance imaging measurements of trochlear depth, sulcus angle, as well as the individual components for measuring trochlear depth (medial, central, and lateral height). Results: The average age of patients at time of surgery was 21 years old (range,13-45). Females were 74% of the population. Average BMI was 26 (17-44) and follow-up averaged 16 months. Table 1 demonstrates the between group differences for the statistically significant variables. These included trochlear depth, and lateral-central difference (via components of trochlear depth calculation) (fig 1). If the patient had lateral condylar height < medial condylar height, a J -sign persisted (4 patients). When the post op C/D >/= 1.2, 5/6 (83%) patients had a persistent j-sign. There were 5 re-dislocations in this population: 2/23 (13%) with a persistent J-sign and 3/40 (8%) without. The KOOS was available for all patients at a minimum of 3 months (Table 2). There was no statistically significant domain that demonstrated a difference between the 2 groups. In both groups, the domains with the lowest scores were quality of life, sports, and symptoms. Conclusions: Dysplastic trochlea that have a small lateral-central difference (<2mm), a shallower trochlear depth, or a lateral condylar height less than the medial condylar height, are more likely to result in a persistent J-sign. In the setting of these dysplastic trochleas, consideration should be given to address trochlear anatomy at the same time as addressing patella height normalization.In the presence of a J-sign, patella height should be normalized to CD < 1.1 to reduce the likelihood of a persistent J-Sign. Post-Op KOOS scores suggest the persistent J-sign does not impact the functional recovery in these patients. In our cohort, there was no increased risk of re-dislocation with a persistent J-Sign.

SURGICAL MANAGEMENT OF PATELLAR INSTABILITY IN ADOLESCENTS WITH BODY MASS INDEX GREATER THAN 30

Background: Recurrent patellar instability is a common condition often requiring surgical stabilization in adolescents. Obesity, defined as body mass index (BMI) greater than 30 kg/m2 in adults, has been associated with poorer outcomes with many procedures including ACL reconstruction, spinal fusion, and joint arthroplasty. Data is limited regarding the results of surgery for patellar instability in adolescent patients with BMI > 30 kg/m2. Purpose: The purpose of this study was to report on rates of recurrent patellar instability following surgical management in adolescents with BMI >30 kg/m2 and to compare the rates of recurrent instability between different surgical procedures. Methods A retrospective review of patients who underwent surgical management of patellar instability at our institution was performed. Inclusion criteria included patients aged 19 and younger, with BMI >30 kg/m2 who were followed for least 12 months post procedure. Patients with underlying collagen or systemic disorders, a history of prior ipsilateral knee surgery, or an osteochondral fragment greater than 10mm were excluded. Complications were defined as any recurrent subluxation or dislocation, or need for subsequent instability surgery. A subgroup analysis was performed to compare recurrent instability rates within our cohort between patients who underwent medial retinacular plication versus all other procedures. Categorical variables were compared using Fisher’s exact test. Statistical significance of p<0.05 was applied. Results: Fifty-five patients were identified. Mean age was 15.6±2.4 years. Mean BMI for this cohort was 34.9± 4.3 kg/m2. 72.7% of patients were female. All patients underwent either medial retincular plication, tibial tubercle osteotomy, MPFL reconstruction or combined procedures (Table 1). At a mean of 3.8 years, 16.4% of all patients had any recurrent subluxation or dislocation including 12.7% who had a recurrent dislocation, and 7.3% who required a revision patellar stabilization procedure. Subgroup analysis revealed that obese patients who underwent isolated medial retinacular plication had higher rates of recurrent subluxation or dislocation (24% vs 10%, p=0.272) including recurrent dislocation (20% vs 6.7%, 0.226), and had significantly higher rates of subsequent instability surgery (16% vs 0%, p=0.037) (Table 2). Conclusion: Adolescents with BMI > 30 who undergo patellar stabilization surgery have notable rates of recurrent subluxation or dislocation and subsequent instability surgery though comparable to results in non-obese patients. Obese patients who underwent medial retinacular plication had higher rates of postoperative instability and significantly higher rates of revision instability surgery compared to those who underwent MPFL reconstruction, tibial tubercle osteotomy or combined procedures. Tables/Figures: [Table: see text][Table: see text]

THE EXTENT OF MEDIAL QUADRICEPS TENDON FEMORAL LIGAMENT (MQTFL) PATELLAR AND QUADRICEPS ATTACHMENT: A PEDIATRIC CADAVERIC STUDY

Background: The most common modern procedure for medial patellar stabilization involves reconstruction of the medial patellofemoral ligament (MPFL) and involves reconstructed ligament attachment to the femur and patella. However, cases of patellar fracture have been reported, particularly in the smaller anatomy of the pediatric population, leading to further investigations of patella stabilizing structures. The medial quadriceps tendon femoral ligament has been identified as a separate structure, connecting the patella to the femur and playing a significant role in patella stability. Reconstruction of this ligament may serve a role in patellar stabilization similar to pedicled quadriceps tendon medial ligamentous reconstructions. The anatomy and relationship of the MQTFL attachment to the quadriceps tendon and proximal pole of the patella has not been described in pediatric specimens. Purpose: To determine the anatomical relationship and attachment of the medial quadriceps tendon femoral ligament (MQTFL) on the patella and quadriceps tendon. Methods: Six pediatric cadaveric knee specimens were dissected to identify the patellar and quadriceps attachment site of the MQTFL. Dissection was facilitated by lateral arthrotomy and identification of the MQTFL thickened fibers from the undersurface of the ligament. Results: Six specimens included patients a mean age of 6 years at time of patient death (three 10-year-old specimens, one 4-year-old, and one 2-month-old specimen). The MQTFL was identified in all specimens. As identified from the undersurface of the everted extensor mechanism, it was found to insert a mean distance of 10.5 mm (range 3.9 – 18.2) from the superior pole of the patella. The attachment distally along the edge of the bony patella measured a mean of 12.7 mm (range 5.4-19.4). Total patellar length, as measured from the posterior articular surface, was a mean of 24.5 mm (range 11.0-35.6). Attachment to the quadriceps tendon averaged 47% of total attachment to both the quadriceps tendon and patella; conversely, direct patellar measurement averaged 53%. Conclusion: This study provides quantitative anatomy to attachment of the MQTFL to the patella and quadriceps tendon. Precise knowledge of these structures will assist to more precisely define the complex relationship between stabilizing structures to the medial patellofemoral joint and assist in patella stabilization procedures, particularly in skeletally immature patients. A lower risk of patellar fracture may be one of the key benefits of this procedure, compared with MPFL reconstruction. FIGURES [Figure: see text] References Fulkerson JP, Edgar C. Medial quadriceps tendon-femoral ligament: Surgical anatomy and reconstruction technique to prevent patella instability. Arthrosc Tech 2013;2:e125- e128. Joseph SM, Fulkerson JP. Medial Quadriceps Tendon Femoral Ligament Reconstruction Technique and Surgical Anatomy. Arthroscopy techniques. 2019 Jan 1;8(1):e57-64. Parikh SN, Wall EJ. Patellar fracture after medial patel- lofemoral ligament surgery: A report of five cases. J Bone Joint Surg Am 2011;93. e97(1-8) Dhinsa BS, Bhamra JS, James C, Dunnet W, Zahn H. Patella fracture after medial patellofemoral ligament reconstruction using suture anchors. Knee 2013;20:605- 608. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med 2012;40:1916-1923 Tanaka MJ. The anatomy of the medial patellofemoral complex. Sports Med Arthrosc 2017;25:e8-e11. Kruckeberg BM, Chahla J, Moatshe G, et al. Quantitative and qualitative analysis of the medial patellar ligaments: An anatomic and radiographic study. Am J Sports Med 2017. 363546517729818 LaPrade RF, Engebretsen AH, Ly TV, Johansen S, Wentorf FA, Engebretsen L. The anatomy of the medial part of the knee. J Bone Joint Surg Am 2007;89:2000- 2010. Mochizuki T, Nimura A, Tateishi T, Yamaguchi K, Muneta T, Akita K. Anatomic study of the attachment of the medial patellofemoral ligament and its characteristic relationships to the vastus intermedius. Knee Surg Sports Traumatol Arthrosc 2013;21:305-310. Nelitz M, Williams SR. Anatomic reconstruction of the medial patellofemoral ligament in children and adolescents using a pedicled quadriceps tendon graft. Arthroscopy techniques. 2014 Apr 1;3(2):e303-8.

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.

Combined medial patellofemoral and medial patellotibial reconstruction for patellar instability: a PRISMA systematic review

Background The medial patellofemoral ligament (MPFL) works in association with the medial patellotibial ligament (MPTL) and the medial patellomeniscal ligament (MPML) to impart stability to the patellofemoral joint. The anatomy and biomechanical characteristics of the MPFL have been well described but little is known about the MPTL and MPML. Several reconstruction procedures of the MPFL with semitendinosus, gracilis, patellar and quadriceps tendons, allografts and synthetic grafts have been described. No clear superiority of one surgical technique over another is evident. Methods A systematic review of the literature was conducted using PRISMA guidelines. Inclusion criteria were articles that reported clinical outcomes of combined reconstruction of MPTL and MPFL. The methodological quality of the articles was determined using the modified Coleman Methodology Score (CMS). Results Nine articles were included, reporting the clinical outcomes of 197 operated knees. The surgical procedures described include hamstrings grafting and transfer of the medial patellar and quadriceps tendons with or without bony procedures to reconstruct the MPTL in association with the MPFL. Overall, good and excellent outcomes were achieved. The median CMS is 70.6 ± 14.4 (range 38 to 84). Conclusion Different techniques are reported, and outcomes are good with low rates of recurrence. The quality of the articles is variable, ranging from low to high. Appropriately powered randomized controlled trials are needed to better understand what the adequate indications for surgery in patients with patellar instability and clinical outcomes are. Combined reconstruction of MPFL and MPTL leads to favourable clinical outcomes, supporting its role as a valid surgical procedure for patellar stabilization.

PATELLAR STABILIZATION PROCEDURES IN THE PEDIATRIC POPULATION: INCIDENCE AND DEMOGRAPHICS

BACKGROUND: Patellar instability is a relatively common condition in the young athletic population. There are multiple surgical options for management of patellar instability including medial patellofemoral ligament reconstruction (MPFL), tibial tubercle osteotomy (TTO), and lateral release, as well as different combinations of these procedures. Prior investigations of the adult population have demonstrated an increase in the amount of surgeries over time. In this study, we investigated the demographics and surgical treatment of patellar instability in pediatric and adolescent patients to determine if 1) there had been more surgeries performed year over year, 2) if there had been a change in the type of surgery performed over time, and 3) if age affected the type of surgery performed. METHODS: We queried a California statewide ambulatory surgery database (OSHPD) for all patients under 20 years old diagnosed with patellar instability or patella dislocations in the state of California from 2008-2016. Relevant ICD-9 diagnostic codes, ICD-10 diagnostic codes, and CPT procedural codes were used to identify and analyze this data. The incidence, concomitant procedures, demographics, hospital type, and insurance type were obtained to descriptively describe this population. RESULTS: 4590 patients under the age of 20 received outpatient surgery for patellar instability in 2008-2016. 1472 of the 4590 included concomitant cartilage procedures, while 2733 of the 4590 were patellar stabilization procedures. The average age was 15.5. Of the 4,590 surgeries, 59.6% were female and 40.4% were male. A total of 273 were surgeries were performed on under 13 year-olds, 1808 on 13-15 year-olds, and 2509 on 16-19 year-olds. Included in these 4590 surgeries were 2733 patellar stabilization procedures of interest. Trends were identified concerning the type of patellar stabilization procedures performed. In the youngest population, MPFL alone is performed most frequently (53% of under 13 cases), followed by lateral release alone (34%) and the combination of MPFL and lateral release (13%). For 13-15 year-olds, more lateral release alone procedures (42% of 13-15 cases) were performed. MPFL alone procedures were 40% of cases, with far less MPFL and lateral release combination procedures (13%), TTO and lateral release combination (3%), and TTO alone (2%). For 16-19 year-olds, the frequency of MPFL alone and lateral release alone each accounted for 40% of the patellar stabilization procedures in this age group. 10% of 16-19 cases were then a combination of MPFL and lateral release procedures. TTO alone (4%), TTO and lateral release (4%), and MPFL and TTO (1%) comprised the final 9% of patella stabilization procedures in our oldest patient category. Procedures performed increased in frequency by age group, as indicated by 5.78% (158 for under 13), 38.6% (1055 for 13-15), and 55.62% (1520 for 16-19) of the total patellar stabilization procedures. The frequency of patellar stabilization procedure categories increased by age group in all categories except for the combination of MPFL and TTO. The same number of MPFL and lateral release procedures were performed, with roughly an equal distribution by age group. Over the nine-year period, trends within the age groups stayed roughly consistent for MPFL and MPFL with lateral release. For the under 13 group, the number also remained consistent for lateral release alone. However, for 13-15 and 16-29, the number of lateral releases performed each year drastically decreased from 2008-2016. Related to the prevalence of older pediatric patients undergoing this surgery, 81% (3706) received care at an adult hospital while 19% (884) were treated at a children’s hospital. The majority of California patients receiving surgery were White (53.9%), followed by Hispanic (26.8%), Other (9.1%), Black (5.4%), and Asian (4.8%) race/ethnicity categories. 3472 patients had private insurance, 859 had MediCal, and 259 had another insurance type. The use of private insurance gradually decreased from 2008, while the rate of MediCal coverage greatly increased. CONCLUSIONS: For the pediatric and adolescent population, the total amount of patellar stabilization procedures performed over time has been stable. However, there has been a decrease in the frequency of lateral releases preformed, with an increase in MPFL reconstructions alone over time and with additional procedures. Age was a factor in determining treatment, and as the patients became older, there was a greater percentage of concomitant cartilage procedures. [Table: see text]