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

Abstract

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.

Is the patella apprehension test a valid diagnostic test for patellar instability? A systematic review

“…17 , 19 , 20 , 21 , 22 , 23 Risk of bias was deemed high in one case series due to missing details of patient demographics. 24 Only three case series carried a low risk of bias. 25 , 26 , 27 There were some concerns regarding the risk of bias in the remaining 19 case series due to their retrospective nature and being performed in a single center.…”

Insall proximal realignment with/without tibial tubercle osteotomy for recurrent patellar instability yields acceptable medium- to long-term results but risk of osteoarthritis progression is considerable

“…A few recent studies report BPII 2.0 scores after MPFL-R with/without additional individualised procedures. Both Zimmermann and Börtlein [ 44 ] and Hiemstra et al [ 18 ] found an increase in BPII 2.0 score from pre – to postoperatively from 29 and 28, to 76 and 74, respectively. Although the mean postoperative score in these studies is higher compared to the current patient series, the follow-up time is considerably shorter and it is unclear whether patients with preoperative signs of patellofemoral OA were included in those studies.…”

“…This difference in findings might be due to the inclusion of TTO in the current treatment strategy. In comparison, studies applying modern MPFL-R - regardless of pathoanatomic features of treated knees - redislocation and/or subluxation rates between 3.4% and 8.4% [ 18 , 43 ] have been seen. One of the few other studies reporting both on luxation and subluxation rates after MPFL-R with/without TTO is that by Enderlein et al [ 15 ].…”

Mental and physical health-related quality of life in patients with recurrent patellar dislocations—a generic and disease-specific quality of life questionnaire assessment

“…This finding supports previous findings that the presence or absence of recurrent patellar dislocation alone is not an adequate parameter to evaluate the success of a treatment [ 21 ]. Studies have reported that even after patellar-stabilizing surgery, individuals cease sport participation [ 24 ], experience ongoing subjective feelings of instability [ 13 ], and fear reinjury [ 15 ]. In addition, complex surgical interventions might expose one’s to additional physical and mental distress, which could further increase fear avoidance behaviour [ 18 ].…”