Introduction of a classification system for patients with patellofemoral instability (WARPS and STAID)

Hiemstra, Laurie A.; Kerslake, Sarah; Lafave, Mark R.; Heard, S. Mark; Buchko, Gregory M

doi:10.1007/s00167-013-2477-0

Cited by 23 publications

(17 citation statements)

References 22 publications

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“…The STAID subtype has a traumatic onset with fewer risky anatomic features, while the WARPS subtype has a traumatic onset of instability with significant risky pathoanatomy. 14,18 The WARPS/STAID classification is scored out of 10, whereby lower scores indicate the WARPS subtype and higher scores represent the STAID subtype. Patellar tilt was measured on computed tomography scan by the angle formed between the posterior femoral condylar line and the line joining the medial and lateral edges of the patella.…”

Section: Methodsmentioning

confidence: 99%

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

2019

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Background: Multiple studies have demonstrated that a number of demographic and pathoanatomic characteristics are associated with patellofemoral instability, recurrence of instability, and less satisfactory results following medial patellofemoral ligament reconstruction (MPFL-R). Despite the growing volume of research, the relationship of risk factors to patient-reported outcome after MPFL-R is unclear. Purpose: To determine if certain pathoanatomic and demographic factors predict disease-specific quality-of-life outcome after isolated MPFL-R for symptomatic patellofemoral instability. Study Design: Cohort study; Level of evidence, 3. Methods: The study analyzed 224 isolated MPFL-Rs. Demographic data were collected, including age at first dislocation, sex, and presence of bilateral instability. Pathoanatomic risk factors included the presence of high-grade trochlear dysplasia, tibial tubercle–trochlear groove (TT-TG) distance, patella alta ratio, Beighton score, and patellar tilt. Other factors included femoral tunnel position accuracy and WARPS/STAID score. Descriptive analyses were conducted, followed by calculation of individual Spearman rank correlation coefficients for the predictor variables versus the Banff Patellofemoral Instability Instrument (BPII) scores. A multivariable regression with stepwise selection was employed to establish the final model predicting BPII score, with all significant variables for alpha ≤ .05 included in the final model. Results: The cohort of 224 patients included 66 (29.5%) males and 158 (70.5%) females, with a mean age of 24.1 years and a mean body mass index of 23.9 kg/m2. The mean age of first patellar dislocation was 15.7 years, and 41.4% of patients had bilateral instability. Pathoanatomic variables within the cohort included the following: high-grade trochlear dysplasia = 41%; mean TT-TG = 14.6 mm, with 16.8% of patients demonstrating a TT-TG ≥18 mm; mean Caton-Deschamps ratio = 1.09, with 22% of patients demonstrating a ratio ≥1.2; and positive Beighton score = 37.5%. The mean BPII score at postoperative 2 years was 67.1 out of 100. A stepwise elimination in the regression model demonstrated no statistically significant 3- or 2-way relationships. Assessment of individual variables indicated that bilateral symptoms ( P = .004), higher age at first dislocation ( P = .024), and femoral tunnel position >10 mm from the Schöttle point ( P = .042) were statistically significant predictors of lower quality-of-life scores. The R2 value for the regression analysis model was 0.07. Conclusion: In this large cohort of patients undergoing isolated MPFL-R for symptomatic lateral patellofemoral instability, a multivariable forward stepwise regression demonstrated that bilateral symptoms, femoral tunnel position, and age at first dislocation were statistically significant predictors of lower postoperative BPII scores. No anatomic risk factors were predictive of quality-of-life outcome score 2 years after MPFL-R surgery. The R2 value indicated that there were many other important contributing factors affecting BPII outcome scores than those explored in this study.

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Section: Methodsmentioning

confidence: 99%

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

2019

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“…The WARPS subtype has atraumatic onset of instability with significant risky pathoanatomy, while the STAID subtype has a traumatic onset with fewer risky anatomic features. 11,13 WARPS is an acronym that represents 5 clinical characteristics: weak, atraumatic, risky anatomy, pain, and subluxation. STAID is an acronym for clinical presentation of the following: strong, traumatic, anatomy normal, instability, and dislocation.…”

Section: Methodsmentioning

confidence: 99%

Age at Time of Surgery but Not Sex Is Related to Outcomes After Medial Patellofemoral Ligament Reconstruction

Hiemstra

Kerslake

2019

Am J Sports Med

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Background: Medial patellofemoral ligament (MPFL) reconstruction has become a well-accepted procedure for recurrent patellofemoral instability. Despite a growing volume of research assessing surgical results, the relationship of age and sex to outcomes after MPFL reconstruction surgery is unclear. Purpose: To investigate whether age at the time of surgery or sex influenced patient-reported quality of life and clinical outcome after MPFL reconstruction for recurrent lateral patellofemoral instability. Study Design: Cohort study; Level of evidence, 3. Methods: Between January 2010 and May 2016, 328 patients underwent primary patellofemoral stabilization. Demographic and clinical data were collected preoperatively. Patients completed the Banff Patellofemoral Instability Instrument (BPII) at the pre- and postoperative visits and were assessed clinically at 12 and 24 months. To assess the effects of age at surgery and sex on BPII, multiple linear regression models were fit predicting BPII at 12 and 24 months. An unadjusted regression was applied with the predictors being age at the time of surgery and sex. A second regression model was applied adjusting for age at first dislocation, grade of trochlear dysplasia, knee hyperextension, and the WARPS/STAID score—a measure of the risky patellofemoral instability characteristics of the patient. Results: Of 328 patients, 298 (91%) had complete data and minimum 12-month BPII scores available for analysis. There were 11 redislocations in the cohort (3.4%), all in female patients. When stratified by sex, baseline characteristics were not statistically different except for higher age at first dislocation ( P = .022) as well as higher WARPS/STAID scores ( P = .006) for males. Age at the time of surgery was statistically significant for each postoperative follow-up, with lower BPII scores apparent for each 10-year increase in age at the time of surgery. In the adjusted model, the WARPS/STAID score was significantly associated with the preoperative BPII score. For the 24-month postoperative BPII scores, age at time of surgery and preoperative WARPS/STAID score were both significant. Lower BPII scores were apparent for each 10-year increase in age at the time of surgery, as well as for lower scores on the WARPS/STAID classification. Conclusion: This study demonstrated that when adjusted for risky pathoanatomy, neither age at first dislocation nor sex influences patient-reported quality of life outcomes after MPFL reconstruction. Age at the time of surgery was correlated with outcome, with lower BPII scores apparent for each 10-year increase in age at the time of MPFL reconstruction.

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“…The concurrent validity of the apprehension test was tested using a Pearson r correlation coefficient for evidence of a relationship between the patients’ VAS apprehension ratings and the postoperative BPII 2.0 scores. The relationship between apprehension and pathoanatomic risk factors was explored using a Pearson r correlation for the Beighton score, patella alta, and WARPS-STAID (Weak, Atraumatic, Risky anatomy, Pain, Subluxation; Strong, Traumatic, normal Anatomy, Instability, Dislocation score) 10 as well as age at first dislocation. A Spearman rho was employed to test the correlation of the patients’ VAS apprehension ratings with the trochlear dysplasia category.…”

Section: Methodsmentioning

confidence: 99%

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

2021

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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.

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Introduction of a classification system for patients with patellofemoral instability (WARPS and STAID)

Abstract: II.

Cited by 23 publications

References 22 publications

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

Age at Time of Surgery but Not Sex Is Related to Outcomes After Medial Patellofemoral Ligament Reconstruction

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

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