Sarah Kerslake

Initial Validity and Reliability of the Banff Patella Instability Instrument

Background: Patellofemoral instability is a well-recognized problem, but there are currently no published patient-reported quality of life outcome measures that are disease specific for the treatment of this population. Purpose: To establish the content validity, initial construct validity, and initial reliability of the Banff Patella Instability Instrument (BPII). Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The content of the BPII was validated using a modified 3-stage Ebel procedure and analysis of floor and ceiling effects. As a measure of internal consistency, the Cronbach α was utilized to assess how reliably the 32 items of the questionnaire measured a similar construct. Test-retest reliability of the BPII was calculated using an intraclass correlation coefficient (ICC). Construct validity was evaluated on 150 questionnaires completed by patients with a confirmed diagnosis of patellofemoral instability. A one-way between-group analysis of variance was employed to determine if the BPII was able to differentiate between patients presenting at the initial orthopaedic consultation relative to patients presenting at 6 months and 12 months postoperatively. Results: Content validity was clearly established as each item in the BPII achieved a minimum of 83.3% agreement (range, 83.3%-100%) for relevance among the expert panelists. The average agreement was 96.9%; 24 items achieved 100% agreement. There was no evidence of floor or ceiling effects. Reliability (internal consistency) of the BPII was established at the initial orthopaedic consultation (α = .91), 6 months postoperatively (α = .97), and 12 months postoperatively (α = .97). Test-retest analysis resulted in an ICC of 0.98 between tests. Construct validity was established as there was a statistically significant difference in BPII scores at the initial orthopaedic consultation and 6-month and 12-month postoperative appointments (F2,146 = 75.62; P < .001). Conclusion: The BPII demonstrates content validity, strong initial reliability, and a statistically significant level of construct validity in patients with patellofemoral instability. This population includes patients with recurrent patellofemoral instability as well as surgically stabilized patients.

Effect of Trochlear Dysplasia on Outcomes After Isolated Soft Tissue Stabilization for Patellar Instability

Background: Trochlear dysplasia is a well-described risk factor for patellofemoral instability. Despite its clear association with the incidence of patellar instability, it is unclear whether the presence of high-grade trochlear dysplasia influences clinical outcome after patellofemoral stabilization. Purpose: To determine whether isolated proximal soft tissue stabilization for patellofemoral instability is as successful in patients with high-grade dysplasia compared with low-grade or no dysplasia, as measured by disease-specific quality-of-life and pain scores. Study Design: Case series; Level of evidence, 4. Methods: A total of 277 patellofemoral stabilization procedures were performed during the study period. An isolated stabilization was performed in 233 patients, and 203 of these patients (87%) had adequate lateral radiographs and complete Banff Patella Instability Instrument (BPII) scores available for assessment. Of these, 152 patients underwent a medial patellofemoral ligament reconstruction (MPFL-R) and 51 patients received a medial patellofemoral ligament imbrication (MPFL-I). There were 21 patients with no trochlear dysplasia, 89 patients with low-grade dysplasia (Dejour type A), and 93 patients with high-grade dysplasia (Dejour types B-D). An independent-samples t test was used to determine the difference between the pre- and postoperative BPII scores. A Spearman rho correlation was calculated between 3 trochlear dysplasia groups and the BPII scores at a mean 24 months after patellofemoral stabilization. An independent-samples t test was used to assess the influence of trochlear bump size on outcomes by stratifying data and assessing for a relationship to BPII scores. Results: The independent-samples t test demonstrated statistically significant improvements in pre- to postoperative BPII scores for both groups. The MPFL-R group improved from a mean BPII score of 24.36 to 65.16 (P < .001), and the MPFL-I group improved from a mean of 28.92 to 73.45 (P < .01). For the MPFL-R patient cohort, the Spearman rho correlation demonstrated a significant relationship between postoperative BPII scores and presence of a trochlear bump and degree of dysplasia (P ≤ .05). Overall, a trochlear bump of ≥5 mm was associated with lower postoperative BPII scores (t(193) = 2.65, η2 = 0.04). Conclusion: This research has established a statistically significant correlation between trochlear dysplasia and disease-specific outcomes after MPFL-R surgery. Overall, there was evidence of significant improvement in disease-specific quality-of-life scores after patellofemoral stabilization surgery. This study is the largest cohort reported to date and therefore adds substantially to the evidence that trochlear dysplasia is a significant risk factor for and predictor of outcome among patients with patellofemoral instability.

Anterior Knee Pain in the Athlete

Given that the patellofemoral joint is one of the most highly loaded in the human body, the high prevalence of anterior knee pain (AKP) in athletes is unsurprising. Athletes with AKP present a significant diagnostic and therapeutic challenge. A clear understanding of the etiology of patellofemoral pain in this population is essential in guiding a focused history and physical examination, and achieving an appropriate diagnosis and treatment approach. This clinical review provides an assessment framework and a guide for neuromuscular function testing, and an overview of the causes and treatments of AKP in this challenging patient population.

Concurrent Validation of the Banff Patella Instability Instrument to the Norwich Patellar Instability Score and the Kujala Score in Patients With Patellofemoral Instability.

Background: The Banff Patella Instability Instrument (BPII) is a disease-specific, patient-reported, quality-of-life outcome measure designed to assess patients with patellofemoral instability. The iterative assessment of the validity, reliability, and responsiveness of a health-related patient-reported outcome measure is vital to the development of a high-quality evaluation tool. Purpose: To assess the concurrent validity of the BPII to the Norwich Patellar Instability (NPI) score and the Kujala score. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 74 patients with a confirmed diagnosis of recurrent patellofemoral instability completed the BPII, NPI, and Kujala scores at the initial orthopaedic consultation. A Pearson r correlation coefficient was computed to determine the relationship between each of these patient-reported outcomes. Results: There were statistically significant correlations between the BPII and the NPI score (r = −0.53; P < .001) as well as the BPII and the Kujala score (r = 0.50; P < .001). Conclusion: This study demonstrated a moderately strong correlation of the BPII to other outcome measures used to evaluate patients with patellofemoral instability. This study adds further validity to the BPII in accordance with the COSMIN (COnsensus-based Standards for the selection of health Measurement INstruments) guidelines.

Medial Patellofemoral Ligament Reconstruction Femoral Tunnel Accuracy: Relationship to Disease-Specific Quality of Life

Background: Medial patellofemoral ligament (MPFL) reconstruction is a procedure aimed to reestablish the checkrein to lateral patellar translation in patients with symptomatic patellofemoral instability. Correct femoral tunnel position is thought to be crucial to successful MPFL reconstruction, but the accuracy of this statement in terms of patient outcomes has not been tested. Purpose: To assess the accuracy of femoral tunnel placement in an MPFL reconstruction cohort and to determine the correlation between tunnel accuracy and a validated disease-specific, patient-reported quality-of-life outcome measure. Study Design: Case series; Level of evidence, 4. Methods: Between June 2008 and February 2014, a total of 206 subjects underwent an MPFL reconstruction. Lateral radiographs were measured to determine the accuracy of the femoral tunnel by measuring the distance from the center of the femoral tunnel to the Schöttle point. Banff Patella Instability Instrument (BPII) scores were collected a mean 24 months postoperatively. Results: A total of 155 (79.5%) subjects had adequate postoperative lateral radiographs and complete BPII scores. The mean duration of follow-up (±SD) was 24.4 ± 8.2 months (range, 12-74 months). Measurement from the center of the femoral tunnel to the Schöttle point resulted in 143 (92.3%) tunnels being categorized as “good” or “ideal.” There were 8 failures in the cohort, none of which occurred in malpositioned tunnels. The mean distance from the center of the MPFL tunnel to the center of the Schöttle point was 5.9 ± 4.2 mm (range, 0.5-25.9 mm). The mean postoperative BPII score was 65.2 ± 22.5 (range, 9.2-100). Pearson r correlation demonstrated no statistically significant relationship between accuracy of femoral tunnel position and BPII score (r = –0.08; 95% CI, –0.24 to 0.08). Conclusion: There was no evidence of a correlation between the accuracy of MPFL reconstruction femoral tunnel in relation to the Schöttle point and disease-specific quality-of-life scores. Graft failure was not related to femoral tunnel placement. The patellofemoral instability population is complex, and patients present with multiple risk factors that, in addition to the accuracy of femoral tunnel position, contribute to quality of life and warrant further investigation.

Factor Analysis and Item Reduction of the Banff Patella Instability Instrument (BPII) Introduction of BPII 2.0

Background: Clinical management of patellofemoral (PF) instability is a challenge, particularly considering the number of variables that should be taken into consideration for treatment. Quality of life is an important measure to consider with this patient population. Purpose: To factor analyze and reduce the total number of items in the Banff Patella Instability Instrument (BPII). Subsequent to the factor analysis, the new, item-reduced BPII 2.0 was tested for validity, reliability, and responsiveness. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Quality of life was measured for PF instability patients (N = 223) through use of the original BPII at their initial consultation. Data from the BPII scores were used in a principal components analysis (PCA) to factor analyze and reduce the total number of items in the original BPII, to create a revised BPII 2.0. The BPII 2.0 underwent content validation (Cronbach alpha, patient interviews, and grade-level checking), construct validation (analysis of variance comparing the initial visit and the 6-, 12-, and 24-month postoperative visits, eta-square), convergent validation (Pearson r correlation to the original BPII), responsiveness testing (eta-square, anchor-based distribution testing), and reliability testing (intraclass correlation coefficient [ICC]). Results: The BPII was successfully reduced from 32 to 23 items with excellent Cronbach alpha values in the new BPII 2.0: initial visit = 0.91; 6-month postoperative visit = 0.96; 12-month postoperative visit = 0.97; and 24-month postoperative visit = 0.76. Grade-level reading for all items was assessed as below grade 12. The BPII 2.0 was able to discriminate between all time periods with significant differences between groups (P < .05). Eta-square was 0.40, demonstrating a medium to large effect size. The BPII significantly correlated with the BPII 2.0 (0.82, 0.90, 0.90, and 0.94 at the initial visit and 6-, 12-, and 24-month postoperative visits, respectively), providing evidence of convergent validity. A significant correlation was found between the 7-point scale and 24-month postoperative BPII 2.0 scores, a sign of anchor-based responsiveness. ICC (2,k) was 0.97, indicating strong reliability. Conclusion: The BPII 2.0 is valid, reliable, and responsive for assessment of patients with PF instability, both surgically and nonsurgically treated.

Accuracy and Learning Curve of Femoral Tunnel Placement in Medial Patellofemoral Ligament Reconstruction

&NA; The purpose of this study was to assess the accuracy of femoral tunnel placement in a medial patellofemoral ligament reconstruction (MPFL‐R) cohort. The secondary purpose was to establish the evidence of a learning curve to achieve acceptable femoral tunnel placement during MPFL‐R. Two surgeons, using lateral radiographs, assessed 73 subjects post‐MPFL‐R. Femoral tunnel accuracy and direction of tunnel error were measured in relation to Schöttles point (A‐T distance). Interrater reliability (intraclass correlation coefficient 2,k) of these measures was calculated. Learning curve of accurate femoral tunnel placement was examined by dividing the patient cohort into quartiles. A one‐way analysis of variance was used to assess the quartiles for accuracy of femoral tunnel position and surgical time. In relation to Schöttles point, 66/73 (90.4%) femoral tunnels were categorized as being in a “good” or “excellent” position and 7/73 (9.6%) were categorized as being in a “poor” position. Evidence of an MPFL‐R learning curve was established via a statistically significant difference in the mean A to T distance for the four quartiles (F [3, 69] = 6.41, p = 0.001). There was also a statistically significant difference in the surgical time for the four quartiles (F [3, 69] = 8.71, p = 0.001). In this series, accurate femoral tunnels were placed more than 90% of the time during MPFL‐R. A clear learning curve for accurate femoral tunnel placement was demonstrated both with respect to distance of the tunnel from Schöttle point and with regard to surgical time. Level of evidence was IV.

Validity, Reliability, and Responsiveness of the Anterior Cruciate Ligament Quality of Life Measure: A Continuation of Its Overall Validation.

Objective: The purpose is to provide more validity, reliability, and responsiveness testing of the anterior cruciate ligament–quality of life instrument (ACL-QOL), particularly in light of consensus-based standards for the selection of health status measurement instruments (COSMIN) guidelines. Design: Prospective case series. Setting: An orthopedic surgical practice for consultation. Patients: A convenience sample of 579 ACL-deficient patients. Intervention: Anterior cruciate ligament reconstructive surgery. Main Outcome Measures: Patients completed the ACL-QOL at initial visit and underwent reconstructive surgery. Patients were followed at 6, 12, and 24 months using the ACL-QOL to determine its validity and responsiveness. Cronbachs alpha was used to determine the unidimensionality of the ACL-QOL. A subset of patients took the ACL-QOL twice in a test–retest reliability analysis (intraclass correlation coefficient or ICC 2,k). Another subset of 24-month postsurgical patients measured the success of their surgery using a 7-point global rating scale of improvement as an anchor-based method of responsiveness. Results: Cronbachs alpha coefficients = 0.93, 0.95, 0.96, and 0.98 at 6, 12, and 24 months, respectively. Intraclass correlation coefficient = 0.60, SEM = 6.16, and confidence interval of 12.1 (CI 95%). Responsiveness was measured by comparing the 4 serial time periods. Patients improved significantly at each time period (P < 0.05, ETA squared 0.61). A 24-month ACL-QOL was significantly correlated (P > 0.05) to being “significantly better” or “somewhat better.” Conclusions: The results of this study added more validity, reliability, and responsiveness for the ACL-QOL. The ACL-QOL has completed 8 of 9 COSMIN criteria.

Quality-of-Life Outcomes of Patients following Patellofemoral Stabilization Surgery: The Influence of Trochlear Dysplasia

&NA; Trochlear dysplasia is a well‐described risk factor for recurrent patellofemoral instability. Despite its clear association with the incidence of patellofemoral instability, it is unclear whether the presence of high‐grade trochlear dysplasia influences clinical outcome after patellofemoral stabilization. The purpose of this study was to assess whether trochlear dysplasia influenced patient‐reported, disease‐specific outcomes in surgically treated patellar instability patients, when risk factors were addressed in accordance with the à la carte surgical approach to the treatment of patellofemoral instability. The study design is of a case series. A total of 318 patellar stabilization procedures were performed during the study period. Of these procedures, 260 had adequate lateral radiographs and complete Banff Patellar Instability Instrument (BPII) scores available for assessment. A Pearson r correlation was calculated between four characteristics of trochlear dysplasia, the BPII total and the BPII symptoms, and physical complaints scores, a mean of 24 months following patellofemoral stabilization. Independent t‐tests were performed between stratified trochlear dysplasia groups (no/low grade and high grade) and all BPII measures. There was a statistically significant correlation between measures of trochlear dysplasia and quality‐of‐life physical symptoms scores, an average of 2 years following patellofemoral stabilization surgery. The BPII symptoms and physical complaints domain score, as well as the individual weakness and stiffness questions, correlated with the classification of trochlear dysplasia as well as the presence of a trochlear bump (p < 0.05). Independent t‐tests demonstrated statistically significant differences between the no/low‐grade and high‐grade dysplasia groups for the BPII stiffness (p = 0.002), BPII weakness (p = 0.05) and BPII symptom, and physical complaints values (p = 0.04). Two additional measures—the 24‐month postoperative total BPII score (p = 0.11) and BPII pain score (p = 0.07)—demonstrated trends toward statistical significance. This research has established a statistically significant correlation between trochlear dysplasia and disease‐specific quality‐of‐life outcomes following patellofemoral stabilization surgery. There was a significant correlation between patient‐reported physical symptoms after surgery and high‐grade trochlear dysplasia.

Outcomes of surgical stabilization in patients with combined ACL deficiency and patellofemoral instability — A case series

BACKGROUND The purpose of this study was to assess the disease-specific quality of life, and the objective clinical and functional outcomes of patients with symptomatic ACL deficiency and patellofemoral instability following surgical stabilization of both ligaments. METHODS Between February 2010 and August 2013, 22 subjects underwent a combined ACL reconstruction and patellofemoral stabilization. The anterior cruciate ligament quality of life questionnaire (ACL-QOL) was completed pre-operatively and two-years post-operatively. Clinical and functional assessments were performed two-years post-operatively. A paired t-test assessed the difference between the pre- and post-operative ACL-QOL scores. Effect size was calculated manually using the Eta squared formula. A Pearson r correlation coefficient assessed for a relationship between the post-operative ACL-QOL scores and functional tests. RESULTS Twenty patients completed the 24-month ACL-QOL, 17/20 completed clinical assessment, and 14/20 completed functional testing. The mean pre-operative ACL-QOL score was 21.20 (SD=7.25, range 5.8 to 31.7) and two-years post-operative it was 65.24 (SD=21.38, range 34.5 to 99.1). The paired t-test demonstrated a statistically significant improvement in ACL-QOL scores; t (19)=9.119, p<.001 (two-tailed). The Eta squared statistic (0.81) indicated a very large effect size. Statistically significant correlations (p<.05) were evident between post-operative ACL-QOL scores and all the operative limb single-leg hop tests. CONCLUSIONS Combined ACL reconstruction and patellofemoral stabilization surgery leads to good results. This patient cohort with chronic ACL-MPFL injuries demonstrated a statistically significant change in disease-specific quality of life following surgery. In addition, the patient-reported outcomes and objective functional testing results correlated. LEVEL OF EVIDENCE Case series - IV.