Patellar Instability Patients Research Articles

Postoperative Access and Compliance Following Medial Patellofemoral Ligament Reconstruction in Hispanic Adolescents Mirrors the Non-Hispanic Adolescent Population.

Disparity in surgical care of patellar instability patients has not been fully investigated in the adolescent Hispanic population. This demographic has been shown to have differences in their care, including a lower rate of surgical treatment for patellar instability. Socioeconomic factors have been cited as a factor that influences patient outcomes and its relationship with ethnicity in context of patellar instability has not been evaluated. Review performed of patients <19 years of age who underwent MPFL reconstruction between September 2008 and December 2015. Demographics, patient median household income data, and clinical variables were collected. Generalized linear mixed model (GLMM) with subject as random effects factor was utilized to evaluate differences between ethnicity groups due to nonindependence of data. It was then expanded to incorporate interactions between ethnicity and income. Ninety-five patellar dislocation events met criteria in 85 adolescents (mean age: 15.5y). Thirty-four (40%) adolescents identified as Hispanic. In univariate analysis no differences were found between Hispanic and non-Hispanic patients. The multivariate GLMM demonstrated a significant interaction between ethnicity and income. The Hispanic group in the >100% State median income category had the highest rate of postoperative clinic appointments attended (P=0.019). The Hispanic group in the <100% State median income category had the lowest rate of physical therapy appointments attended (P=0.044). No differences were observed for duration of follow-up (P=0.57) or final Kujala score (P=0.75). Hispanic ethnicity alone is not associated with inferior postoperative management after MPFL reconstruction in adolescents. However, when socioeconomic status is considered, Hispanic patients of lower-income backgrounds are found to have lower compliance with postoperative rehab recommendations. Level III.

Evaluation of the Results of Reconstruction of Medial Patellofemoral Ligament in the Treatment of Recurrent Patellar Instability Using Hamstring Autograft by Dual Patella Docking Technique

Abstract Background: Recurrent patellar instability can significantly affect a patient’s life quality. This study evaluated the results of medial patellofemoral ligament (MPFL) reconstruction in the recurrent patellar instability treatment using hamstring autograft by dual patellar docking technique. Materials and Methods: This prospective study was performed on 20 recurrent patellar instability patients. Magnetic resonance imaging and computed tomography scans were performed to confirm MPFL tear and assess the tibial tubercle-trochlear groove distance. Various clinical and radiographic evaluations were performed preoperatively. The surgical technique involved diagnostic arthroscopy, graft preparation, patellar preparation, graft passage, femoral tunnel preparation, and graft fixation. Results: Postoperatively, a substantial progression was observed in the International Knee Documentation Committee score, Kujala score, Cincinnati score, and Lysholm score compared to preoperative values (P &lt; 0.001). In addition, the postoperative measurements of patellar tilt angle and patellar congruence angle were significantly lower than their respective preoperative values (P &lt; 0.001). All 20 (100%) patients had negative findings in the postapprehension test, indicating improved stability. In the postcompression test, 3 (15%) patients showed positive results, whereas 17 (85%) patients had negative results. In terms of complications, 2 (10%) patients experienced patellofemoral pain, 1 (5%) patient had residual patellar translation without dislocation, 1 (5%) patient had limited flexion, and the majority of patients (16, 80%) had no complications. Conclusions: MPFL reconstruction with patellar docking yielded good results with Kujala and Lysholm, as well as adequate, satisfactory congruence angles for most patients. This procedure has exhibited a high success rate in addressing patellofemoral instability.

Correlations of Different Objective and Patient Related Outcome Measures for Patellar Instability Patients

Correlations of Different Objective and Patient Related Outcome Measures for Patellar Instability Patients

Association between single leg hop tests and patient reported outcome measures and patellar instability in patients with recurrent patellar dislocations

ObjectivesTo assess the associations between the single leg hop tests at two premises; baseline and the change after 12 months, and change in patient reported outcome measures and persistent instability...

Wavelet Analysis of Rearfoot Loading of Patients After Medial Patellofemoral Ligament (MPFL) Reconstruction

Abstract Introduction. Patellar instability in younger patients is a common injury (3.3% of all knee injury episodes) and the most frequent dislocation of the knee observed. The sensitivity and reliability of clinical diagnostic tests after medial patellofemoral ligament (MPFL) reconstruction remain unclear and biased. The primary aim of the present study was thus to detect, using wavelet analysis, differences in the rearfoot loading of the operated limb of patients after MPFL reconstruction. The authors hypothesised that applying this specific examination technique would allow for more accurate and less biased clinical results evaluation. Material and Methods. The study involved a group of 15 female subjects (age: 22.8 ± 6.3 years; weight: 58.5 ± 5.1 kg) after MPFL reconstruction and a control group of 29 healthy females (23.2 ± 2.8 years; 61.1 ± 7.7 kg). The subjects performed a 30-second classic Romberg test on a treadmill (Noraxon FDN-T) equipped with a matrix of baroresistive sensors to measure ground reaction forces. Time-frequency analysis of the signal originating from the treadmill was done using an analytic Morse wavelet. Results. The results indicate differences in visual control and vestibular stability in patients before and 3 months after a surgery. They are characterised by a deficit of energy attributed to visual control in favour of an excess of energy associated with vestibular control. Patellar instability patients show greater energy expenditure to maintain body balance for at least 6 months after MPFL reconstruction. Conclusions. Patellar instability patients have increased vestibular control while maintaining balance. Our results suggest an extended rehabilitation period for patients after MPFL reconstruction beyond 6 months.

Trochleoplasty: Groove-Deepening, Recession Wedge, and Entrance Grooveplasty

Patellar instability in patients with a dysplastic trochlea can be challenging to treat without addressing the trochlea directly. Trochleoplasty allows the surgeon to target a root osseous cause of instability and is an effective treatment option in well-selected patients. This chapter explores the variations in trochleoplasty techniques and offers an overview of recently published data associated with this surgery.

Tibial Tuberosity Rotation in Patients With Patellar Instability Versus Age- and Sex-Matched Controls.

Several methods have been described to measure external rotation of the tibial tuberosity; all use femoral landmarks. To develop reproducible tibial-based methods to measure external rotation of the tibial tuberosity in patients with patellar instability. Cross-sectional study; Level of evidence, 3. Included were magnetic resonance images of 61 patients with patellar instability and 61 age- and sex-matched healthy controls. Three novel methods using tibial landmarks to measure the rotation of the tibial tuberosity (plateau axis-tuberosity axis [PA-TA] angle, tibial geometric center-tuberosity axis [GC-TA] angle, and plateau axis-midtuberosity point [PA-MT] angle) as well as a femoral-based rotational measurement (surgical transepicondylar axis-tuberosity axis [sTEA-TA] angle) and the tibial tuberosity-trochlear groove (TT-TG) distance were measured and compared in instability patients and controls using unpaired t tests, and the cutoff values for predicting instability were calculated using receiver operating characteristic curves. The correlations between the angle measurements and the TT-TG distance were analyzed. Instability patients had significantly higher external rotation of the tibial tuberosity compared with controls with regard to the PA-TA angle (18.2° ± 9.6° versus 13.1° ± 6.8°; P = .001), GC-TA angle (8.4° ± 4.5° versus 11.5° ± 3.9°; P = .0001) and sTEA-TA angle (122° ± 8.5° versus 113.6° ± 6.3°; P = .0001). The mean TT-TG distance was also significantly higher in the instability group (18.2 ± 5.4 versus 11.5 ± 2.7 mm; P = .001). The cutoff values were 17.5° (area under the receiver operating characteristic curve [AUC] = 0.66) for PA-TA angle, 8.5° (AUC = 0.705) for GC-TA angle, 118.8° (AUC = 0.79) for sTEA-TA angle, and 15.2 mm for TT-TG distance (AUC = 0.863). PA-TA angle was significantly correlated with all other measurements (r = 0.35-0.71; P ≤ .006 for all), whereas sTEA-TA angle had the strongest correlation with TT-TG distance (r = 0.78; P = .001). The tibial tuberosity was externally rotated in patellar instability patients compared with age- and sex-matched controls, and this intrinsic malalignment of the proximal tibia was demonstrated in the tibial-based measurements.

Medium to long-term outcomes of medial patellofemoral ligament reconstruction using the superficial quadriceps versus a hamstring autograft in patellar instability patients

Medial patellofemoral ligament (MPFL) reconstruction is a standard procedure in patellar dislocation patients. Superficial quadriceps autografts (QA) and hamstring autografts (HA) are popular graft choices in MPFL reconstruction with the lack of directly compared clinical studies between both methods. A total of 43 patellar instability patients, who underwent QA and HA for patellar stabilization at a specified center between 2012 and 2021, were retrospectively reviewed. 21 QA and 22 HA patients were 52.4% of males and 47.6% females with a median age of 25 years (range 12–58) in the QA group, while 63.6% were females with a median age of 21 years (range 14–58) in the HA group. The mean follow-up period was 46.9 months (range 24–77) in QA and 61 months (range 24–100) in the HA group. At the final follow-up, no complications were observed with either technique. No patients presented with recurrent dislocations after surgery. There was no statistically significant difference in postoperative mean Kujala scores (QA = 94.9+/− 4.1 and HA = 94.2+/− 8.0, p = 0.73) or the mean Lysholm scores (QA = 94.1+/− 5.0 and HA = 93.2+/− 7.0, p = 0.61).

Home ownership, full-time employment, and other markers of higher socioeconomic status are predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction

BackgroundThe purpose of this study was to identify socioeconomic predictors of time to initial evaluation, time to surgery, and postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction (MPFLR).MethodsWe conducted a retrospective review of patients at our institution who underwent primary MPFLR with allograft from 2011 to 2019 and had minimum 12-month follow-up. Patients were administered an email survey in January 2022 to assess symptom history, socioeconomic status, and postoperative outcomes including VAS satisfaction and Kujala score. Predictors of time to initial evaluation, time to surgery, and postoperative outcomes were identified using multivariable linear and logistic regression with stepwise selection.ResultsSeventy patients were included in the cohort (mean age 24.8 years, 72.9% female, mean follow-up time 45.7 months). Mean time to evaluation was 6.4 months (range 0–221) and mean time to surgery was 73.6 months (range 0–444). Having a general health check-up in the year prior to surgery was predictive of shorter time to initial evaluation (β = − 100.5 [− 174.5, − 26.5], p = 0.008). Home ownership was predictive of shorter time to surgery (β = − 56.5 [− 104.7, 8.3], p = 0.02). Full-time employment was predictive of higher VAS satisfaction (β = 14.1 [4.3, 23.9], p = 0.006) and higher Kujala score (β = 8.7 [0.9, 16.5], p = 0.03).ConclusionMarkers of higher socioeconomic status including having a general check-up in the year prior to surgery, home ownership, and full-time employment were predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes.Level of evidence: IV, retrospective case series.

The Value of Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State for Commonly Used Patient-Reported Outcomes in Recurrent Patellar Instability Patients After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer

To identify the minimal clinically important difference (MCID), substantial clinical benefit (SCB) and patient acceptable symptomatic state (PASS) for commonly used patient-reported outcomes (PROs) in recurrent patellar instability patients after medial patellofemoral ligament reconstruction (MPFLR) and tibial tubercle transfer (TTT), and to determine the impact of potential prognostic factors on the likelihood of achieving these values. From April 2015 to February 2021, patients who underwent MPFLR and TTT were retrospectively reviewed. PROs included Kujala, Knee Injury and Osteoarthritis Outcome (KOOS), Lysholm, International Knee Documentation Committee (IKDC) and Tegner score. Relevant anchor questions were provided. A distribution- or anchor-based method was adopted to determine the MCID, SCB and PASS. Minimal detectable change (MDC) was included to confirm the validity. Univariate regression analyses were conducted to determine the potential prognostic factors. 142 patients were included. The MCID were 9.1(Kujala), 11.1 (Lysholm), 0.9(Tegner), 9.9(IKDC), 9.0(KOOS-Pain), 10.8(KOOS-Symptoms), 10.0(KOOS-Activities of Daily Living (ADL)), 17.8(KOOS-Sports and Recreation (Sports/Rec)), and 12.7 (KOOS-Quality of Life (QoL)). The SCB were 14.5(Kujala), 12.5(Lysholm), 1.5(Tegner), 14.5(IKDC), 13.9(KOOS-Pain), 14.3(KOOS-Symptoms), 18.4(KOOS-ADL), 47.5(KOOS-Sports/Rec), 15.0(KOOS-QoL). The PASSs were 85.5(Kujala), 75.5(Lysholm), 3.5(Tegner), 73.2(IKDC), 87.5(KOOS-Pain), 73.2(KOOS-Symptoms), 92.0(KOOS-ADL), 77.5(KOOS-Sports/Rec), and 53.1(KOOS-QoL). All SCBs were valid except KOOS-QoL. All MCIDs were valid at the 95% confidence interval (CI) except KOOS scores, the majority of which were valid at the 90% CI. A younger age was an independent prognostic factor of reaching PASS for Lysholm, IKDC, Tegner and KOOS-ADL score. A higher baseline score was a negative prognostic factor for achieving MCID or SCB but had a slightly positive influence on the achievement of PASS. This study established the MCID, SCB, and PASS for commonly used PROs and confirmed their validity in recurrent patellar instability patients after MPFLR and TTT. Younger age and lower baseline scores were prognostic factors of achieving MCID and SCB, while patients with higher baseline scores were more likely to report satisfaction.

Differences in the Severity and Location of Patellofemoral Cartilage Damage Between Instability Patients With and Without Patella Alta.

Patella alta is a risk factor for recurrent patellar instability. Differences in chondral injury in patients with patellar instability between patella alta and patella norma have not been evaluated. To analyze whether preoperative cartilage damage differs in severity and location between patellar instability patients with and without patella alta. Cohort study; Level of evidence, 3. Patients with patellar instability who underwent patellar realignment surgery at a single institution with preoperative magnetic resonance imaging (MRI) scans were included. After measurement of Caton-Deschamps index (CDI) on MRI, patients were divided into patella alta (CDI ≥1.3) and patella norma groups. The area measurement and depth and underlying structures (AMADEUS) score was used to quantify cartilage defect severity on MRI. A total of 121 patients were divided into patella alta (n = 50) and patella norma (n = 71) groups. The groups did not differ significantly in sex ratio, age at MRI, body mass index, mean reported number of previous dislocations, or mean interval between first reported dislocation and date of MRI. A total of 34 (68%) of the patella alta group and 44 (62%) of the patella norma group had chondral defects (P = .625) with no significant between-group differences in defect size (P = .419). In both groups, chondral injuries most affected the medial patellar facet (55% in patella alta vs 52% in patella norma), followed by the lateral facet (25% vs 18%), and lateral femoral condyle (10% vs 14%). A smaller proportion of patients had full-thickness defects in the patella alta compared with the patella norma group (60% vs 82%; P = .030). The overall AMADEUS score was higher for the patella alta versus the patella norma group (68.9 vs 62.1; P = .023), indicating superior articular cartilage status. Patients with patella alta had less severe cartilage injury after patellar instability, including a lower proportion with full-thickness defects and better overall cartilage grade. The location of injury when present was similar between alta and norma, with most defects affecting the medial facet, lateral facet, and lateral femoral condyle in descending frequency.

Poster 295: Surgical Management and Outcomes of Patellar Instability in Hispanic Adolescents Mirrors the General Adolescent Population

Objectives: Literature has shown that there are differences in care across demographics for sports- related injuries. Delay to physician evaluation, delay to surgery, and decreased surgical management has been documented in common pathology such as ACL tears and Shoulder Instability. Recent research has demonstrated that for Patellar Instability in adolescents, African-American patients had lower odds of having surgical management in addition to their care costing more overall, even when controlled for insurance status. The Hispanic population is a growing minority group who face challenges not just in economic status, but language barriers that may also impart inequitable care for one of the most common diagnoses seen in a Sports clinic. The purpose of this study is to assess for any major differences in care provided to adolescent patients who identify as Hispanic compared to the remainder of the adolescent population. Methods: Patellar Instability patients who underwent MPFL Reconstruction at a single center between September 2008 through December 2015 were collected. Inclusion criteria were age &lt; 19 at time of surgery, preoperative and postoperative data available during chart review, case was performed as the index primary reconstructive procedure, and minimum of 3 month follow-up data available. Charts were reviewed to gather demographic and clinical information including age, sex, race, ethnicity, number of instability episodes, MRI at time of initial evaluation, time from injury to surgery, engagement in postoperative physical therapy, number of postoperative visits attended, Kujala score, and complications. Independent variable t-test was used for analysis of number of clinic visits, therapy sessions, and the Kujala score. The remainder of analysis was completed using χ2 testing. Significance was set at p = 0.05. Results: 95 patients (40 male (42%), 55 female (58%)) met the inclusion criteria. Mean patient age was 15.5. 37 patients identified as Hispanic (38.9%) and 58 (61.1%) of patients identified as non-Hispanic. 58.5% of all patients had an MRI available at their first clinic visit, 69.2% of patients had 2 or more dislocation events prior to surgery, and 37% of patients were formally cleared for return to activity. Hispanic patients more frequently had an MRI prior to surgery compared to non-Hispanic patients (73% vs 50%, p = .039). Otherwise, there was no statistically significant difference in observations between Hispanics patients and non-Hispanic patients, including number of dislocations prior to surgery (p = 0.13), number of clinic visits preoperatively or postoperatively (p = 0.51 and 0.09, respectively), number of therapy sessions attended postoperatively (p = 0.46), or the patient reported outcome as measured by the Kujala score (mean = 91.56 vs 95.25, p = 0.13). Complications in the cohort included 1 infection and 1 case of arthrofibrosis. 2 patients in the Hispanic cohort required revision for recurrent instability compared with 5 patients in the non-Hispanic cohort (p = 0.56). Conclusions: Adolescents with patellar instability who identify as Hispanic had similar outcomes scores and complication rates after operative treatment in the form of MPFL Reconstruction. Hispanic patients more frequently had an MRI at their first clinic visit prior to surgery, but the remainder of the perioperative work-up and care was similar to the non-Hispanic cohort. Though significant deviations in care were not found in this study, reviews to elucidate any variations in care should continue in efforts to ensure equitable treatment of at-risk populations.

Poster 139: Utilization of 3D Statistical Shape Modeling of Anatomic Variation Across a Cohort of Patella Instability Patients

Poster 139: Utilization of 3D Statistical Shape Modeling of Anatomic Variation Across a Cohort of Patella Instability Patients

Poster 141: Does the Traditional TT-TG Distance Accurately Reflect the Relative Position of the Tibial Tubercle to the Trochlear Groove? A Three-Dimensional Analysis

Objectives: The tibial tubercle to trochlear groove (TT-TG) distance often guides surgical decision- making for patellar instability. Traditional TT-TG measurements are limited by interrater reliability and lack of consideration for variable anatomy throughout flexion. The purpose of this study was to compare the traditional TT-TG measurement to three-dimensional measures generated from automated trochlear groove detection with sequential radial slices on magnetic resonance imaging (MRI). Methods: Twenty-four knees (4 healthy controls, 20 patellar instability patients) were segmented into three-dimensional distal femur and tibia models. A custom-designed program was employed to detect the trochlear groove through its course based on the shortest distance to the origin in a polar (radial) axis defined by the distal femoral condyles. The program also identified the surface projection of the tibial tubercle center of mass. The medial-lateral distance between the trochlear groove and tibial tubercle was calculated for the first 45 degrees of the detected groove to generate radial TT-TG (rTT-TG) values. The mean and maximum rTT-TG values were compared to the traditional TT-TG MRI measurement performed by one grader. Results: Mean rTT-TG values were significantly greater than traditional measurements (21.8 mm versus 17.9 mm, p=.003) with moderate correlation between measurements (Pearson r = 0.59, p=.002). In Dejour C and D dysplasia, the mean rTT-TG measurements trended towards being greater than traditional measurements (C: 24.3 mm versus 16.6 mm; D: 28.5 mm versus 21.8 mm; p=0.057 for both comparisons). Dejour C dysplasia demonstrated a significantly greater maximum rTT-TG than the traditional measurement (27.9 mm versus 16.6 mm, p=0.029), and Dejour D dysplasia demonstrated a similar trend (30.2 mm versus 21.8 mm; p=0.057). Conclusions: Traditional TT-TG distances may underestimate the true medial-lateral offset between trochlear groove and tibial tubercle, particularly in patients with high- grade dysplasia. This represents a potential alternative to the current standard measurement techniques which may improve measurement reliability by automation. Our study suggests that utilizing 3D radial TT-TG values via automated measurement may more accurately portray the variable anatomy of the trochlear entrance and offer a standardized alternative to a frequently used measurement to overcome reader reliability.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Primary Patellar Instability and Need for Recurrent Surgical Stabilization.

Vitamin D has been proven experimentally to affect musculoskeletal health. The purpose of this study was to identify the relationship between vitamin D deficiency and patellar instability. Vitamin D deficiency is associated with an increased risk of experiencing primary patellar instability and recurrent patellar dislocation after primary surgical stabilization. Retrospective comparative study. Level 3. A 1:1 matched retrospective study of 328,011 patients diagnosed with vitamin D deficiency was performed using the PearlDiver database. Incidence of primary patellar instability was calculated according to sex and age. Rates of primary patellar instability and surgical stabilization for recurrent dislocation were calculated with sex- and age-specific stratifications. Multivariable logistic regression was used to compare the rates of primary injury and recurrent stabilization while controlling for demographics and medical comorbidities. A total of 656,022 patients were analyzed. The overall 1-year incidence rate of patellar instability in patients with vitamin D deficiency was 82.6 per 100,000 person-years (95% CI, 73.2-92.9), compared with 48.5 (95% CI, 41.4-56.5) in the matched control. Women were significantly more likely to experience primary patellar instability within 1 (adjusted odds ratio [aOR] = 1.45; 95% CI, 1.12-1.88) and 2 years (aOR, 1.31; 95% CI, 1.07-1.59) of hypovitaminosis D diagnosis. Patients aged 10 to 25 years with hypovitaminosis D were at greater risk of requiring recurrent patellar stabilization for both men (aOR, 2.48; 95% CI, 1.06-5.80) and women (aOR, 1.77; 95% CI, 1.04-3.02). Patients diagnosed with vitamin D deficiency experienced higher rates of primary patellar instability and have greater risk of requiring recurrent surgical stabilization for subsequent dislocations. These results suggest that monitoring and proactively treating vitamin D deficiency in the physically active patient may lower the risk of suffering primary patellar instability or recurrence after surgical stabilization.

Podium Presentation Title: Factors Affecting the Tibial Tubercle to Trochlear Groove Distance in Patellar Instability Patients

Podium Presentation Title: Factors Affecting the Tibial Tubercle to Trochlear Groove Distance in Patellar Instability Patients

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

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

Paper 04: Differences in the Severity and Location of Patellofemoral Cartilage Damage Between Instability Patients With and Without Patella Alta

Objectives: Patellar instability is estimated to affect approximately 150 out of 100,000 adolescents between the age of 14-18 years old, a rate which is expected to increase over time. Several risk factors have been associated with patellar instability such as younger age, trochlear dysplasia and patella alta. Patella alta is defined as a superiorly-positioned patella, commonly determined using the Caton-Deschamps Index (CDI), with a ratio of 1.3 or greater indicative of patella alta. Patients with patella alta are approximately 2.5-4.0 times more likely to suffer a recurrent patellar dislocation, which is thought to be due to the changes in biomechanics seen in patella alta. Differences in chondral injury in patients with patellar instability between patella alta and patella norma has not been evaluated. Our objective was to retrospectively analyze whether preoperative cartilage damage differs in severity and location between patellar instability patients with and without patella alta. Methods: Patients with patellar instability who underwent patellar realignment surgery at a single institution with a preoperative MRI within 3 months were included. After measurement of CDI on MRI, patients were divided into patella alta (CDI&gt;1.3) and patella norma groups. To quantify cartilage defect severity, the Magnetic Resonance Imaging Score and Classification system (AMADEUS) was utilized by two sports medicine clinical fellows. The AMADEUS score characterizes cartilage defect size, defect depth, presence of subchondral bone defects, and bone marrow edema. The scale is scored 0-100 with 100 indicating no cartilage damage. In patients with multiple cartilage defects on MRI, each defect was characterized and analyzed independently. Continuous variable data were reported as means with standard deviations and categorical data reported as frequencies with percentages. The distribution of data was assessed with the Shapiro-Wilk test. Continuous data were assessed with the Student’s t test and Mann-Whitney U tests as appropriate. Categorical data were assessed with chi-squared analysis. The threshold for significance was set to p &lt; 0.05. Multivariate analysis was conducted with defect depth, bone edema, and AMADEUS score as the dependent variable. All statistical analyses were performed with R Studio (Version 3.6.3, Vienna, Austria). Results: One hundred-twenty-one patients were divided into patella alta (n=50) and patella norma (n=71). The groups did not significantly differ in sex ratio, age at MRI, body mass index (BMI), mean reported number of prior dislocations, or mean interval between first reported dislocation and date of MRI. Thirty-four (68%) of the patella alta group and 44 (62%) of the patella norma group had chondral defects ( P=0.625) with no statistically significant difference in the size of the chondral defects between the groups ( P=0.419). In both groups, chondral injuries most affected the medial patellar facet (55% in patella alta vs. 52% in patella norma), followed by the lateral facet (25% vs 18%), and lateral femoral condyle (10% vs 14%)( P=0.859). The patella alta group had a smaller proportion of patients who had full thickness defects in comparison to the patella norma group (60% vs 82%; P=0.030). The overall AMADEUS score for the patella alta group was higher (68.9 vs. 62.1; P=0.023) compared to the patella norma group, indicating superior articular cartilage status. When looking at a multivariate regression using AMADEUS score as the dependent outcome, female sex shows an increase in AMADEUS score with a beta estimate of 11.96 ( P&lt;0.001). Female sex also shows a higher probability of having no defect associated bone marrow edema (Odds ratio:6.7; P=0.010), and a higher probability of partial-thickness defect rather than full-thickness (Odds ratio:3.9; P=0.004). Age, BMI, interval between dislocation and MRI, and reported number of dislocations were not found to be associated with total AMADEUS score, probability of having defect-associated bone marrow edema, or defect depth. Conclusions: There is a high percentage of cartilage injury in patients with a history of patellar instability with over 60% of patients showing cartilage damage on MRI. Patients with normal patellar height have a higher frequency of full thickness cartilage defects and more severe injury compared to those with patella alta. The location of cartilage injury between alta and norma is similar, with most defects affecting the medial facet, lateral facet, and lateral femoral condyle in descending frequency.

Three-Dimensional Printing of the Patellofemoral Joints of Patellar Instability Patients

Three-dimensional (3D) modeling and printing comprise an important tool for orthopaedic surgeons. One area in which 3D modeling has the potential to dramatically improve our understanding of biomechanical kinematics is pathologies of the patellofemoral joint, in particular trochlear dysplasia. We describe a method for creating 3D printed models of the patellofemoral joint, including computed tomography image acquisition, image segmentation, model creation, and 3D printing. The models created can help surgeons understand and plan surgery for recurrent patellar dislocations.

Poster 244: Pain Catastrophizing in Patellar Instability Patients Undergoing MPFL Reconstruction

Objectives:Pain catastrophizing was established as a way to measure patient perception and response to pain, as represented by three subscores: rumination, magnification, and helplessness. Prior clinical studies have demonstrated the close relationship between pain catastrophizing and persistent postoperative pain after total knee arthroplasty. Among patellofemoral instability patients, pain catastrophizing has also been investigated. However, specific patient factors that contribute to greater degrees of pain catastrophizing in patellofemoral instability are not yet understood. Additionally, investigations of the association between preoperative catastrophizing and postoperative pain are limited. Therefore, the purpose of this study is to investigate risk factors for higher preoperative pain catastrophizing and its correlation with pain scores following medial patellofemoral ligament reconstruction (MPFLR).Methods:This study retrospectively evaluated patients who underwent MPFLR between 2015 and 2020 with preoperative pain catastrophizing scores (PCS). Patient demographics were collected to evaluate risk factors for worse PCS scores. Four overlapping questions from the KOOS JR and full KOOS questionnaires were utilized at the preoperative and 6 months postoperative time points to assess pain on a scale from 0 (least) to 4 (most), including pain with: 1.) Knee Twisting, 2.) Knee Straightening, 3.) Stair Climbing, and 4.) Standing Upright.Results:Thirty-four patients were included for analysis. Higher age at the time of surgery was significantly associated with worse Helplessness (R2=0.11, p=.035), Rumination (R2=0.18, p=.020), and Total PCS scores (R2=0.08, p=.039). Patients with >5 instability events reported significantly worse Rumination (2.29±2.87 vs 4.60±3.31, p=.049). At 6 months post-operatively, 32.35% of patients (11/34) continued to report moderate pain in at least one pain category. These patients reported significantly greater Rumination at baseline (2.91 ± 3.37 vs 6.64 ± 5.22, p = .017). Lastly, higher baseline Helplessness significantly correlated with greater improvement in pain with stairs (p = .049), higher Magnification significantly correlated with greater improvement in pain with standing (p = .012), and higher baseline Total PCS correlated with more improvement in pain with stairs (p = .035) and standing (p = .037). Multivariate analysis demonstrated that history of prior surgery and age remained independently predictive of postoperative pain scores (Table 1).Conclusions:Older age and >5 instability events at presentation were patient risk factors associated with increased pain catastrophizing. Pain catastrophizing had different correlations with postoperative pain depending on subscore, with higher Rumination associated with persistent moderate pain while higher Magnification or Helplessness correlated with greater improvement in pain. However, on multivariate analyses the only significant independent predictors of persistent moderate to severe post-operative pain at 6 months were age and history of prior surgery. Further investigation is needed to determine whether pain catastrophizing is an innate patient factor with post-operative implications or merely an effect of prolonged symptoms in patellar instability patients.Table 1.Multivarite Linear regression model evaluating indepentant predictors of worse postoperative pain scores