Symptomatic Patellar Instability Research Articles

GUIDED GROWTH SURGERY FOR TREATMENT OF PATELLAR INSTABILITY IN GENU VALGUM

IntroductionGenu valgum is a common presentation in paediatric patients with congenital limb deformities. The aim of this study is to assess the outcome of guided growth surgery in paediatric patients referred via our physiotherapy pathway with isolated genu valgum and associated patellar instability.Materials & MethodsPatients were identified from our prospective patellar instability database. Inclusion criteria was acquired or congenital genu valgum associated with patellar instability in skeletally immature patients. The mechanical lateral-distal femoral angle was assessed on long leg alignment radiographs (mLDFA <85 degrees). Surgical treatment was the placement of a guided growth plate (PediPlate, OrthoPediatrics, USA) on the medial distal femoral physis (hemi-epiphysiodesis). KOOS-child scores were collected pre-operatively and post-operatively (minimum at 6 months).ResultsEleven patients (seven female) with mean age of 12(range 5–15) were identified. Five patients had congenital talipes equinovarus(CTEV), one fibular hemimelia, one di-George syndrome, one septic growth arrest and three had idiopathic genu valgum. Pre- and post-operative KOOS-child scores showed overall improvement: 58(range 36–68) to 88(65–99) and knee symptoms subscores: 64(43–71) to 96(68–100) p<0.01, t-test.Mean follow-up was 10 months (range 3–23). No subsequent dislocations/subluxations occurred during follow-up.ConclusionsGuided growth surgery is an effective way of treating symptomatic patellar instability in skeletally immature patients with genu valgum in the absence of other structural pathology. It was most common in our cohort in patients with unilateral CTEV. We would recommend to screen syndromic and congenital limb deformity patients for patellar instability symptoms in the presence of genu valgum.

Poster 276: Assessment of Trochlear Cartilage Thickness and Volume Using Sagittal Magnetic Resonance Images to Quantify Trochlear Dysplasia: A Matched-Cohort Study

Objectives: Trochlear dysplasia is considered a major contributing factor for patellar instability. More recently, trochleoplasty procedures have become popularized to address this morphological abnormality. Both thick and thin flap trochleoplasty techniques exist, with the goal to deepen the trochlea while avoiding perforation of the trochlear cartilage during the procedure. However, the relative cartilage thickness in the dysplastic trochlea has not been well described. This study aimed to assess trochlear cartilage thickness and volume in knees with and without patellar instability and the relationship to measurements of trochlear dysplasia. Methods: 25 knees with symptomatic patellar instability were compared with 25 gender-matched knees. Retrospective chart review was performed to obtain demographic data. On sagittal images, trochlear cartilage thickness (TCT) and trochlear cartilage volume (TCV) were analyzed at the center, medial border, and lateral border of the trochlea. TCT was defined as the cartilage thickness halfway along the trochlear length at its maximum dimension. TCV was defined by total area of cartilage proximal to the plane of the intercondylar midpoint. Symptomatic and control values were compared using paired sample t-test. Stepwise multivariate linear regression was performed to assess for associations with standard radiographic parameters of trochlear dysplasia. Results: TCT was significantly different between the medial, central and lateral trochlea in both the symptomatic and control groups (p<0.001). Only lateral TCT demonstrated a significant difference between groups, which was 20.3% (p=0.035) thicker in the symptomatic cohort compared to controls. No significant differences existed in TCV between symptomatic and control groups. In females, central TCT was 28.3% thicker in the symptomatic cohort (p=0.024), while medial TCV was 2.3x greater (p = 0.019). Males failed to demonstrate gender specific differences. Regression analysis demonstrated that patient height showed a significant relationship with all measurements except for medial TCV. Central TCT demonstrated a significant, independent relationship with trochlear depth (Coefficient 0.38, p = 0.011), while central TCV demonstrated a significant, independent relationship with trochlear depth (Coefficient 9.9, p <0.001), sulcus angle (Coefficient 1.1, p <0.001), and lateral trochlear inclination (Coefficient -1.1, p <0.001). Conclusions: While trochlear dysplasia typically refers to abnormal bony morphology, this study demonstrates the role of differential contributions of chondral thickness and volume between knees with and without patellar instability, and that these measurements correlated with severity of dysplasia. Future studies should further investigate the relationship between TCT and TCV with other dysplasia parameters to better inform the surgical considerations of performing trochleoplasty in the treatment of patellar instability. [Table: see text]

Poster 251: Patients who Undergo Bilateral Medial Patellofemoral Ligament Reconstruction Return to Sport at a Similar Rate to Unilaterals: A Matched Cohort Study

Objectives: Lateral patellar instability is a debilitating condition not only to athletes, but also a broad range of highly active individuals. Many of these patients experience instability symptoms bilaterally. Medial patellofemoral ligament reconstruction (MPFLR) is indicated to prevent future recurrence and ideally facilitate a complete return to sports (RTS). While RTS has been examined following MPFLR, the rate and timing of RTS in patients that undergo MPFLR bilaterally is unknown. The purpose of this study is to compare patients who have received bilateral MPFLR to a matched unilateral cohort, to elucidate potential differences and eventually allow better prognostication of this unique population’s ability to return to sports. Methods: Patients who underwent primary MPFL reconstructions with minimum 12-months clinical follow-up were identified from a single institution from the years 2011 to 2021. Those who underwent non-simultaneous primary MPFL reconstruction of bilateral knees were identified, as well as cohort of unilateral MPFLR. Surveys were then disseminated, including the Visual Analog Scale (VAS) for pain and satisfaction, the Kujala Anterior Knee Pain Scale, the Tegner Activity Scale, and the MPFL-RSI assessing psychological readiness to RTS. Detailed baseline sport activity and RTS information was collected, which was modified for bilateral patients to report on each procedure. For analysis, bilateral and unilateral MPFLRs were matched in a 1:2 ratio based on age, sex, BMI, and status of concomitant tibial tubercle osteotomy (TTO). A sub-analysis was performed comparing patients who underwent concomitant TTO compared to isolated MPFLR. Outcomes were compared between cohorts using T-tests and Chi-square analyses when required. Bivariate linear regression and logistic regression were performed to assess correlation between RTS and outcome scores, as well as psychological readiness. Results: Surveys were completed by 24 patients who underwent bilateral MPFL reconstruction and 105 unilateral patients with a total mean follow-up time of 4.2 ± 2.4 years. Among the bilateral patients, average time between MPFL procedures was 19.3 ± 16.9 months; notably, 71.4% of patients had symptoms in the contralateral knee at the time of index procedure. Three bilateral patients were unable to be matched, resulting in a 21:42 match with respective bilateral and unilateral cohorts having a mean age (22.5 ± 5.7 vs 23.3 ± 6.6 years; p = 0.65), sex (males 9/21 vs 18/42; p = 1.00), BMI (25.87 ± 6.39 vs 25.21 ± 4.78 kg/m2; p = 0.65), and concomitant TTO (9/18 vs 18/42; p = 1.00) that did not significantly differ, indicating successful matching. When comparing matched cohorts, bilateral MPFLR patients returned-to-sport at a similar rate to unilaterals following both their first (61.1% vs 63.2%; p = 0.98) and second MPFLR (72.7% vs 63.2%; p = 0.82). After undergoing both procedures, 33.3% of the bilateral cohort was able to return to their preinjury level of sport, compared to 26.3% of unilaterals (p = 0.82). The mean time for bilateral patient to RTS following their first procedure was 24.3 ± 7.5 weeks and 22.5 ± 12.9 weeks after their second, compared to the unilateral time-to-return taking 38.5 ± 23.0 weeks, though this difference at each time point (bilateral index vs unilateral; bilateral contralateral vs unilateral) did not reach significance (p = 0.06; p = 0.08). All patients scored highly with respect to VAS surgery satisfaction (85.4 vs 82.8; p = 0.44). There were no significant differences found between bilateral and unilateral cohorts for the Kulaja score (79.0 vs 86.1; p = 0.14) or in psychological readiness to RTS as indicated by the MPFL-RSI (49.7 ± 24.2 vs 58.8 ± 26.7; p = 0.24). Regression analysis found both the Kujala score (β = 0.06, p = 0.01) and MPFL-RSI (β = 0.06, p < 0.01) to be weakly, but significantly associated with rate of RTS. Sub-analysis of MPFLR with and without concomitant TTO did not demonstrate any significant differences with respect to RTS, psychological readiness, or any other outcome score (p > 0.05). Conclusions: The results of this study suggest that patients who undergo MPFLR bilaterally are able to return to sports at a similar rate and to a similar level compared to a matched unilateral comparison group with equivalent satisfaction and functional outcome scores. These findings are particularly important due to the high prevalence of simultaneous bilateral symptomatic patellar instability. With no demonstrable differences in rate and timing of return-to-sport, knee function, and psychological readiness between patients who have undergone unilateral versus bilateral MPFLR, surgeons can more confidently report equivalent outcomes to patients particularly with respect to RTS rates.

Association of Trochlear Length on Sagittal MRI to Trochlear Dysplasia in Knees With Patellar Instability.

Trochlear dysplasia is a primary risk factor for patellar instability and leads to loss of the osteochondral constraint of the patella. Trochleoplasty techniques include the Peterson grooveplasty, which alters the length of the trochlea; however, a radiographic measurement of trochlear length to support this has not been described. To describe measurements to quantify trochlear length on sagittal magnetic resonance imaging in patients with and without patellar instability and to correlate trochlear length with measurements of trochlear dysplasia. Cross-sectional study; Level of evidence, 3. A total of 66 age- and sex-matched knees (36 female and 30 male; mean age, 20.8 ± 4.8 years) were included in this study, of which 33 had patellar instability. Trochlear extension length (TEL) and trochlear alpha angle (TAA) were measured on 3 sagittal magnetic resonance imaging scans (center of the knee, center of the medial condyle, and center of the lateral condyle), and measurements were compared between symptomatic and control knees. Receiver operating characteristic curve analysis was performed, and the area under the curve (AUC) was calculated to describe the accuracy of each measurement to distinguish between knees with and without patellar instability. Linear and multivariate regression analyses were performed to assess the relationship between sagittal measurements and axial measurements of trochlear dysplasia, including lateral trochlear inclination, sulcus angle, and trochlear depth, as well as patient size reflected by the epicondylar distance. In symptomatic knees, the central trochlea extended more proximally than in control knees, as determined by the TEL (14.0 ± 3.0 vs 11.5 ± 2.3 mm, respectively; P < .001) and TAA (68.4° ± 3.8° vs 70.5° ± 3.4°, respectively; P = .017). AUC calculations showed that a TEL ≥11 mm at the central trochlea was predictive of patellar instability in both male and female knees (AUC = 0.83 and 0.77, respectively), as was a TAA ≤67° in female knees (AUC = 0.72). An independent association between the central TEL and sulcus angle was found. The central TEL showed a weak correlation with patient size, as measured by the epicondylar distance, while the TAA did not. In knees with symptomatic patellar instability, the central trochlea was found to extend 2.5 mm more proximally than in control knees, and this increase in length correlated with severity of trochlear dysplasia. As radiographic examinations of the trochlea and grooveplasty procedures are often based on the proximal extent of the cartilaginous trochlea, further studies are needed to identify the role of trochlear length in the assessment and treatment of trochlear dysplasia in the setting of patellar instability.

Paper 52: Sex-Based Differences in Outcomes After MPFL Reconstruction

Objectives:The purpose of the current study was to investigate whether pain, function, satisfaction, or return to play (RTP) differ between sexes post-operatively in those undergoing MPFL reconstruction for symptomatic patellar instability.Methods:A retrospective review of patients who underwent an MPFL reconstruction for symptomatic patellar instability was performed. Kujala score, Visual Analogue Scale (VAS), patient satisfaction, willingness to undergo surgery again, revisions, return to play (RTP) and MPFL-RSI score were evaluated. Clinical outcomes were compared between male and female patients. A p value of <0.05 was considered to be statistically significant.Results:Our study included 141 knees that underwent MPFLR, and the patient population was 69.5% female. Post-operatively, the mean VAS score at rest was 1.0 ± 1.7 in male patients and 1.6 ± 2.1 in female patients (p= 0.0963). The mean Kujala score was 88.8 ± 13.3 and 83.5 ± 16.1 for male and female patients respectively (p=0.1062). Overall, there was a significant difference in RTP, with male patients returning at higher rates (58.1% vs 33.3%, p = 0.0479). The mean VAS score during activity was significantly lower in male patients at 1.8 compared to female patients at 3 (p=0.016). MPFL-RSI-score was also significantly worse in female patients (69.5 vs 55.6, p = 0.0098). While female patients had slightly higher rates of recurrent subjective instability (14.3% vs 11.7%) and re-dislocation (2% vs 0%), the difference was not statistically significant (p = 0.6731 and 0.3490, respectively). Female patients demonstrated higher rates of additional surgery at long term follow up, though this difference was also not statistically significant (12.2% vs 4.6%, p = 0.1674).Conclusions:Female patients had worse clinical outcomes than males undergoing MPFLR for patellar instability, with significantly lower rates of RTP, VAS score during sport and MPFL-RSI scores with a trend towards lower Kujala score and VAS score.

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BackgroundTrochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty. MethodsBetween 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient’s latest follow-up assessment. ResultsThe mean age at operation was 22y (SD ± 4.7, range 14–37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12–60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m2) was associated with inferior outcomes. ConclusionTrochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.

Medial patellofemoral ligament MRI abnormalities in the setting of MCL injuries: are they clinically relevant?

To assess MRI abnormalities of the medial patellofemoral ligament (MPFL) in patients with clinically and MRI-proven superficial medial collateral ligament (sMCL) injuries and determine the clinical significance. High-field strength knee MRI examinations were selected which demonstrated sMCL injuries. These cases were retrospectively reviewed for the presence, location, and severity of MPFL abnormality. The MPFL was divided into a more superior transverse component arising from a femoral attachment (tMPFL), and a broader more inferior oblique decussation component (odMPFL) arising from the anterior margin of the upper sMCL. Chart review was performed to determine the clinical relevance of any MPFL findings. One hundred patients with MCL injury were identified. These included 37 grade I sprains, 33 partial tears, 20 high-grade partial tears, and 10 full thickness tears. Abnormal edema was present at the femoral attachment of the tMPFL in 83%. The odMPFL was abnormal in 90%, most commonly involving the femoral third. No patients had imaging evidence of concurrent lateral patellar dislocation on the initial MRI study. No patients had documented patellofemoral instability at the time of original injury or upon follow-up. No patients required MPFL reconstruction. The MRI appearance of the MPFL is abnormal in the majority of patients with clinically and MRI-documented sMCL sprains and tears. These cases had no evidence of concurrent lateral patellar dislocation on the initial MRI and did not develop patellar instability symptoms.

Technical Considerations for an Anteromedializing Tibial Tubercle Osteotomy

Background: Tibial tubercle osteotomy and distal realignment allows for adjustment to the patellofemoral articulation in order to improve patellar tracking and redistribute patellar contract pressures. Indications: A healthy, active 39-year-old woman status post right knee tibial tubercle osteotomy presented with &gt;2 years of patellar instability symptoms in the left knee. Imaging revealed a tibial tubercle to trochlear groove (TT-TG) distance of 21 mm and patellar tendon lateral trochlear ridge (PT-LTR) distance of 14 mm. Technique Description: After knee arthroscopy is performed, an open incision is made along the inferomedial patellar tendon. Two pilot holes are created before a sagittal saw is used to make the tibial tubercle osteotomy, before completing it with an osteotome. Anteromedialization and/or distalization of the osteotomy is performed relative to templated values in order to improve patellar articulation. After correction, 3 bicortical screws are placed to achieve stable fixation. Results: There were no immediate complications following surgery. Surgical management led to improvement of the patient’s patellofemoral pain, which allowed return to prior baseline level of function. Discussion/Conclusion: The preferred technique for an anteromedialzing tibial tubercle osteotomy is presented. An anteromedializing tibial tubercle osteotomy is an effective surgical option for patients with evidence of patellar maltracking or central or lateral patellar chondromalacia whom have failed conservative management. This case demonstrates the efficacy of an anteromedializing tibial tubercle osteotomy to provide pain relief by improving patellar tracking and offloading patellar contact pressures on areas of prominent chondral wear.

Coronal and Transverse Malalignment in Pediatric Patellofemoral Instability.

Patellofemoral instability (PFI) encompasses symptomatic patellar instability, patella subluxations, and frank dislocations. Previous studies have estimated the incidence of acute patellar dislocation at 43 per 100,000 children younger than age 16 years. The medial patellofemoral ligament (MPFL) complex is a static soft tissue constraint that stabilizes the patellofemoral joint serving as a checkrein to prevent lateral displacement. The causes of PFI are multifactorial and not attributed solely to anatomic features within the knee joint proper. Specific anatomic features to consider include patella alta, increased tibial tubercle–trochlear groove distance, genu valgum, external tibial torsion, femoral anteversion, and ligamentous laxity. The purpose of this paper is to provide a review of the evaluation of PFI in the pediatric and adolescent patient with a specific focus on the contributions of coronal and transverse plane deformities. Moreover, a framework will be provided for the incorporation of bony procedures to address these issues.

Medial patellofemoral ligament reconstruction for patellofemoral instability: a new surgical technique

&lt;p class="abstract"&gt;&lt;span lang="EN-US"&gt;The purpose of this study was to present new surgical technique for MPFL reconstruction. We also describe its functional outcome, complications, and the advantages of the procedure. This study is a prospective analysis of collected data during the period of august 2018 to January 2020. Ten cases of patients with recurrent symptomatic patellar instability and who underwent isolated MPFL reconstruction were included in the study. Kujala scoring and lysholm scoring was done to assess the functional outcome at follow-up. Post-operative dislocation and apprehension were recorded in each case along with any complication. Pre-operative Kujala score was 36.80 which improved to 89.80 postoperatively at the time follow-up. Pre-operative lysholm score was 36.80 which improved to 92.70 postoperatively at the time follow-up. The improvement in Kujala score and Lysholm score was found to be highly significant (p&amp;lt;0.01). We have done a simple technique where MPFL is reconstructed anatomically to restore kinematics and stability. Consistent good results with early rehabilitation can be obtained using the described technique.&lt;/span&gt;&lt;/p&gt;

Modified technique for medial patellofemoral ligament reconstruction – Its outcome with 2-year follow-up

Objectives: The purpose of this study was to present our modified technique for MPFL reconstruction. We also present its functional outcome, complications, and patients’ satisfaction from the procedure. Materials and Method: This study is a retrospective analysis of prospectively collected data during the period of July 2015 and March 2019. Forty cases in patients with recurrent symptomatic patellar instability without a patellar fracture and who underwent isolated MPFL reconstruction were included in the study. Kujala scoring was done to assess the functional outcome at follow-up. Post-operative dislocation and apprehension were recorded in each case along with any complication. Patients were asked to complete a subjective questionnaire postoperatively during follow-up, to assess their satisfaction with the surgical procedure. Results: Pre-operative Kujala score was 45.85 which improved to 92.72 postoperatively at the time follow-up. The improvement in Kujala score was found to be highly significant (P &lt; 0.01). Subjective assessment of the procedure: 72.5% of the patients had an excellent outcome. About 15% of the patients had a good outcome whereas 10% had a fair outcome. Only one patient had a poor outcome. Conclusion: In properly selected patients with recurrent patellar instability, isolated MPFL reconstruction appears to be a safe and efficient surgical procedure for the stabilization of patella, with a low failure rate. Consistent good results with early rehabilitation can be obtained using suture anchors to fix the implant on patella and using the described technique.

The morphology of patella changed significantly after soft tissue correction for children with recurrent patella dislocation

BackgroundAlthough morphological improvement of femoral trochlea has been investigated in children with patellar dislocation after surgery, whether the patellar shape changed under the same condition is still unknown. The purpose of the study was to investigate the changes of patellar morphology in transverse plane following surgical correction of recurrent patellar dislocation in children.MethodsA total of 22 patients with a mean age of 9.9 years (7 to 12) were included. All had unilateral recurrent patellar dislocation. The knees with recurrent patellar dislocation were treated with medial patellar retinaculum plasty and defined as the affected side. The contralateral knees with no symptom of patellar instability were considered as the unaffected side. All patients were treated between October 2014 and August 2018. Axial CT (Computed Tomography) scans were undertaken in all patients to assess the patella morphological characteristics on a particular axial image preoperatively and at the final follow-up.ResultsThere were not significant differences about patellar transverse diameter, thickness and Wiberg angle between affected side and unaffected side before surgery and at the last follow-up respectively (The mean follow-up period: 28.0 ± 3.3 months). However, before surgery, the Wiberg-index in the affected side (0.74 ± 0.06) was significantly different from that in the unaffected side (0.64 ± 0.04). At the last follow-up, the Wiberg-index in the affected side (0.67 ± 0.05) and the unaffected side (0.65 ± 0.04) were not significantly different. Also, in the affected side, the Wiberg-index at the last follow-up was significantly lower than that before surgery (P < 0.05). The Wiberg-index in the unaffected side was not significantly different before surgery and at the last follow-up.ConclusionThe patellar morphology can change significantly after surgical procedures in children with patellar recurrent dislocation whose epiphysis is not closed.

Trochlear dysplasia influences patellotrochlear index when measuring patella alta

Objectives:Patella alta is a risk factor for patellar instability and its recurrence after treatment. The patellotrochlear index (PTI) is a measurement used to quantify patella alta, describing patellar engagement in the trochlea through an index of trochlear overlap with patellar articular surface based on sagittal imaging. Values less than 20% have been reported to indicate patella alta, yet this measurement has primarily been described in normal knees. Trochlear dysplasia is also a common risk factor in patellar instability and can affect the length of the trochlea. Therefore the purpose of this study was to compare PTI measurements in knees with and without trochlear dysplasia, and to describe its relationship with trochlear length.Methods:Knees with trochlear dysplasia (defined by trochlear depth<4mm) based on CT imaging were identified from a series of knees with symptomatic patellar instability and compared to age- and gender matched asymptomatic controls. Measurements of patellar height including PTI and Caton Deschamps Index (CDI) were performed, as well as additional measurements of trochlear dysplasia including lateral trochlear inclination [LTI] and sulcus angle [SA]. Trochlear length was quantified using a previously described method of trochlear center-edge angle (TCEA) measurement, an angle between the posterior femoral cortical line with its intersection with Blumensaat’s line to the most proximal margin of the trochlea, with a smaller angle indicating more proximal extension of the trochlea. TCEA was measured at the central, medial, and lateral trochlea. Measurements were compared between dysplastic and control groups using t-test. Linear and multivariate regression analyses were performed to assess the relationship between PTI and measurements of trochlear dysplasia.Results:21 knees with trochlear dysplasia (13 female and 8 male) were included in this study, and were compared with 21 age- and gender-matched controls. In the dysplastic group, trochlear depth (TD) was 0.7+/-2.4mm vs 6.8+/-2.5mm (p<0.001) in the control group, SA was 154.2+/-11.5 degrees vs 134.0+/-8.3 degrees (p<0.001), and LTI was 12.1+/-6.2 vs 23.7+/-4.4 degrees (p<0.001) . Despite CDI being greater in the symptomatic group (1.19+/-0.23 vs 1.06+/-0.19, p=0.053), PTI was greater (with more overlap) in the symptomatic group (34.92+/-15.23% vs 25.43+/-21.55%, p=0.076). In the symptomatic group, the trochlear groove extended more proximally at the central (TCEA 58.4 degrees vs 68.6 degrees, p<0.001) and medial aspects (68.9 degrees vs 77.9 degrees, p<0.001). In dysplastic knees, PTI demonstrated a weak negative correlation with TCEA (R=-0.40) and with LTI (R=-0.45).Conclusion:In this study, knees with trochlear dysplasia had a PTI of 35% vs 25% in the control group, indicating greater patellar engagement despite having greater measurements of patella alta based on CDI (1.19 vs 1.06). PTI correlated with increased proximal extension of the trochlea which may account for the greater patellofemoral overlap. As abnormal trochlear length can associated with supratrochlear spurs, greater values on PTI may not necessarily indicate functional patellofemoral engagement. Further studies are needed to identify the functional relationship between trochlear length and patella alta.

CORR Synthesis: Can Guided Growth for Angular Deformity Correction Be Applied to Management of Pediatric Patellofemoral Instability?

CORR Synthesis: Can Guided Growth for Angular Deformity Correction Be Applied to Management of Pediatric Patellofemoral Instability?

Anteroposterior distance between the tibial tuberosity and trochlear groove in patients with patellar instability

BackgroundOur objective was to describe a measurement to assess sagittal tibial tuberosity (TT)–trochlear groove (TG) distance and to compare this between asymptomatic (control) patients and patients with symptomatic patellar instability. MethodsWe compared static CT images of 22 fully extended knees of patients with symptomatic patellar instability with images of 22 asymptomatic knees. TT–TG distance was measured to quantify lateralization of the TT, and anteroposterior TT–TG distance was used to quantify the sagittal distance between these two points. Lateral trochlear inclination, sulcus angle, and trochlear depth were measured. Groups were compared using paired t tests (alpha = 0.05). Correlations of anteroposterior TT–TG distance with lateral trochlear inclination, sulcus angle, and trochlear depth were assessed using linear and multivariate regression. ResultsMean TT–TG distances were 19.9 ± 4.4 mm (symptomatic) and 16.8 ± 5.5 mm (control) (mean ± std deviation) (P = 0.002). Mean anteroposterior TT–TG distances were 8.3 ± 7.8 mm (symptomatic) and −0.5 ± 4.6 mm (control) (P < 0.0001). The symptomatic group had greater measurements of trochlear dysplasia, with lower lateral trochlear inclination, greater sulcus angle, and lower trochlear depth (all P < 0.0001). Anteroposterior TT–TG distance and trochlear depth were strongly negatively correlated (r = 0.62, R2 = 0.39, P < 0.0001). ConclusionsIn asymptomatic patients, the anteroposterior TT–TG distance was −0.5 mm, indicating that the TG and TT were nearly in the same coronal plane. In patients with symptomatic patellar instability, the TG was almost nine millimeters anterior, and this distance correlated with measurements of trochlear dysplasia. Level of evidenceIII, case control study.

LATERAL PATELLAR INCLINATION IN CHILDREN AND ADOLESCENTS: MODIFIED MEASUREMENT TECHNIQUE TO CHARACTERIZE PATELLAR INSTABILITY

Background: Patellar instability (PI), although rare, occurs most often in younger patients with underlying pathoanatomy. Patellar tilt is one of many identified risk factors for PI. Lateral patellar inclination (LPI) angle measures patellar tilt relative to the distal femur as viewed on the axial MRI with the widest cross-section of the patella. The LPI measurement has historically been described with reference to the posterior aspect of the femur at the same transverse level as the widest cross-section of the patella. Given the transitional anatomy of the distal femur and variable heights of the patella, the LPI may be better represented by referencing the axis of the fully formed posterior condyles. The posterior condyles represent a true axis of rotation that serves as an internal reference for knee motion and are clearly visible on MRI. Normative values for LPI have not been established and accepted in the literature; and, proposed maximum thresholds range from 10° to 20°. We hypothesized that a modified LPI measurement (LPI) referencing the posterior condylar axis would be different from the apparent LPI (ALPI) as measured historically in a pediatric and adolescent population. Given the clarity of fully formed posterior condyles as compared with the posterior femur transitioning from the shaft to the condyles, we also hypothesized that the modified LPI would have higher inter- and intra-rater reliability than the ALPI measurements. Methods: Patients aged 9 to 18 years and treated for PI at our tertiary referral center between January 2014 and August 2017 were identified. The ALPI measurement was made as previously described on axial MRI images (Figure 1). The LPI was measured with reference to the posterior condylar orientation (Figure 2 A-B). All measurements were performed by two independent observers. A cohort was randomly selected from these patients and measurements were performed for this cohort by three independent observers and re-performed after a minimum of two weeks. Inter- and intra-rater correlation coefficients were calculated for this subgroup and regression analysis was performed on the entire cohort. Results: Sixty-five patients met inclusion criteria for this study, and thirty patients were randomly selected for reliability analysis. The ALPI inter-rater reliability (ICC = 0.708, 95% CI: 0.47 – 0.85) showed good agreement while that of the LPI (ICC = 0.885, 95% CI: 0.77 – 0.95) also showed good agreement with less variability. Intra-rater reliability for ALPI (ICC = 0.975, 95% CI: 0.95-0.99) was similar to the intra-rater reliability for LPI (ICC = 0.975, 95% CI: 0.95-0.99). In the entire cohort of 65 patients, the average ALPI (14.6+/-9.9°) was 6.1+/-3.4° less than the average LPI (19.6+/-9.4°) (p = 0.037). Referencing a previously described maximum threshold of 13.5° for LPI, 46% of the patients in the cohort had normal tilt based on ALPI measurements while only 27% of patients in the cohort had normal tilt based on new LPI measurements. Conclusion: The LPI measurement has similar inter and intra rater reliability with less inter-rater variability compared to the historical measurement (ALPI). A significant difference in patellar tilt was found between the two techniques of measuring LPI with the historical technique underestimating the amount of tilt present. Furthermore, a larger percentage of this PI patient cohort would be classified as having normal patellar tilt based on the ALPI measurement than would be classified as abnormal based on the LPI measurement. When assessing children and adolescents with symptomatic PI, the LPI measurement referencing the posterior condylar axis provides more consistent and more representative measurements of the true patellar tilt. Previously described threshold values for patellar tilt should be re-examined using this new measurement technique to appropriately risk stratify patients with PI as historical measurements appear to underestimate this pathoanatomy. [Figure: see text][Figure: see text]

Anatomic double-bundle medial patellofemoral ligament reconstruction with aperture fixation using an adjustable-length loop device: a 2-year follow-up study

BackgroundTo assess the clinical availability of an adjustable-length loop device for use in the double-bundle technique with aperture fixation at the patella and femur during anatomic double-bundle medial patellofemoral ligament reconstruction (DB-MPFLR) for recurrent patellar dislocation.MethodsWe retrospectively investigated 11 patients (12 knees) with recurrent patellar dislocation who underwent anatomic DB-MPFLR with an ipsilateral semitendinosus tendon autograft. The graft was folded in half, and its central portion was hanged using the adjustable-length loop device. Both free ends of the graft were fixed at the proximal and distal ends of the medial edge of the patella by using suture anchors, and the hanged graft loop was pulled into the femoral tunnel while maintaining equal tension on both bundles. Manual traction of the suture loops was applied to fix the graft appropriately in full range of motion (ROM) of the knee joint under arthroscopic guidance. Clinical outcomes such as re-dislocation, ROM, clinical scores (Kujala score, Lysholm score, and visual analogue scale score for anterior knee pain), and complications were assessed preoperatively and at 2 years postoperatively. Radiographic parameters indicating patellar position, including congruence angle and lateral patellofemoral angle, were measured at 4 different angles of knee flexion (30°, 45°, 60°, and 90°).ResultsAt 4 different flexion angles of the knee joint, the preoperative congruence angle decreased significantly and the lateral patellofemoral angle increased significantly at the final follow-up (P < 0.001). Notably, the improvements in these angles were maintained with no significant differences at the 4 different flexion angles. None of the patients experienced subluxation or re-dislocation after surgery. The patellar instability symptoms improved, as confirmed on the basis of radiographic and other clinical outcomes.ConclusionNew DB technique with aperture fixation at the patella and femur by using an adjustable-length loop device offers high stability with full ROM of the knee joint, can be considered as a feasible procedure and technique for recurrent patellar dislocation.

Patellar position in patients with patellofemoral syndrome as characterized by anatomo-radiographic study

ObjectivesTo determine the prevalence of high patella in adult patients with knee pain, and to correlate patellar height with symptoms of patellar instability, episode of patellofemoral dislocation and anterior pain in the knee; and also verify the concordance correlation between the Insall-Salvati and Caton-Deschamps indices. MethodCross-sectional study analyzing the medical records of patients with knee pain, using lateral view knee radiographs with 30° degrees of flexion and computed tomography. The values of the Insall-Salvati index and the Caton-Deschamps index were used to determine the patellar height. ResultsA total of 756 records were analyzed, resulting in 140 knees studied, 39% men and 61% women. Both indices produced statistically significant associations for the occurrence of high patella and signs of instability and episodes of dislocation, but there was no significant association for anterior knee pain. The Kappa index obtained when analyzing the concordance correlation between the Insall-Salvati index and Caton-Deschamps index points to a regular association between them. ConclusionPatients with high patella present a higher prevalence of instability. Having a high patella has no significant relationship with the presence of anterior knee pain. The Insall-Salvati and Caton-Deschamps indices demonstrate a regular agreement on the presentation of patellar heights results.

Surgical Treatment With Closing-Wedge Distal Femoral Osteotomy for Recurrent Patellar Dislocation With Genu Valgum

Background: Closing-wedge distal femoral osteotomy (CWDFO)—combined with medial reefing and lateral release, if necessary— has been used to treat recurrent patellar dislocation (RPD) with genu valgum. Purpose: To evaluate the clinical and radiologic outcomes of surgical treatment with CWDFO for treatment of RPD with genu valgum. Study Design: Case series; Level of evidence, 4. Methods: Fourteen consecutive patients (23 knees) with RPD and genu valgum were treated with CWDFO. Patients with a minimum 2-year follow-up period were eligible for this study. Patients with prior failed surgery were also eligible. Radiographic evaluation was performed with mechanical femorotibial and lateral distal femoral angle. The radiographic parameters presenting patellar positions and pathologic abnormalities associated with RPD were evaluated. Chondral lesion changes in second-look arthroscopic examination were examined, and clinical outcomes (eg, occurrence of redislocation, range of motion, and clinical scores) were assessed pre- and postoperatively at a minimum of 2 years. Results: At a mean follow-up of 30.7 months (range, 25-62 months), the mean mechanical femorotibial and mechanical lateral distal femoral angles changed significantly from valgus 5° (range, 2°-11°) to varus 3° (2°-11°; P < .001) and from 83° (range, 78°-86°) to 89° (84°-92°; P < .001), respectively. The mean patellar congruence angle improved from 40° lateral (range, 20°-53° lateral) to 4° medial (23° medial to 21° lateral; P < .001), as did the lateral patellofemoral angle from 26° (range, 8°-62°) to 9° (0°-15°; P < .001). Computed tomography scans showed that the mean distance of patellar lateral shift decreased from 13.5 mm (range, 4-22 mm) to 2.0 mm (–4 to 5 mm; P < .001). The mean tibial tubercle to trochlear groove distance significantly decreased from 20.4 to 13.5 mm (P < .001), while the Caton-Deschamps ratio did not change significantly after surgery (P = .984). Chondral lesions of the patella and trochlear groove significantly improved or were maintained. None of the patients experienced subluxation or redislocation after surgery. Patellar instability symptoms also improved, as validated by radiographic and other clinical outcomes. Conclusion: CWDFO combined with medial reefing and lateral release successfully treated RPD with genu valgum for a minimum follow-up of 2 years, with improved patellar alignment and stability.

Current Concepts in the Management of Patellar Instability

Patellar instability is a common presenting clinical entity in the field of orthopedics. This not only can occur from baseline morphologic variability within the patellofemoral articulation and alignment, but also from traumatic injury. While conservative management is many times employed early in the treatment course, symptomatic patellar instability can persist. This article reviews the available indexed published literature regarding patellar instability. Given the debilitating nature of this condition and the long term sequelae that can evolve from its lack of adequate recognition and treatment, this article details the most current methods in the evaluation of this entity as well as reviews the most up-to-date surgical treatment regimens that are available to address this condition.