Identifying Patients With Patella Alta and/or Severe Trochlear Dysplasia Through the Presence of Patellar Apprehension in Higher Degrees of Flexion

Background: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle–trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as tibial tubercle osteotomy or trochleoplasty. The indications to perform such procedures are traditionally based on imaging criteria but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. Hypothesis: The persistence of patellar apprehension at greater than 60° of knee flexion is associated with patella alta, an increased TT-TG distance, and trochlear dysplasia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 76 patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeatedly assessed as the knee was flexed in 10° intervals, as measured using a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain radiographs and magnetic resonance imaging (MRI) scans were obtained for all patients. Patellar height was assessed with the Caton-Deschamps (CD) index, and trochlear morphology was assessed through measurements of the sulcus angle and depth on MRI and classified using the Dejour classification system. Imaging measurements of patients in whom apprehension resolved by 60° of knee flexion were compared with measurements for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60° of flexion in 56 patients and persisted into deeper flexion in 20 patients. The patients with a delayed resolution of apprehension demonstrated a higher CD index; elevated TT-TG distance; increased sulcus angle; decreased sulcus depth; and higher incidence of Dejour type B, C, or D dysplasia (all P < .05). Of the 20 patients with a delayed resolution of apprehension, 18 had either Dejour type B, C, or D dysplasia or a CD index of at least 1.30. A delayed resolution of apprehension was present in 11 of the 16 patients with Dejour type B, C, or D dysplasia. Conclusion: Overall, 90% of patients with significant patella alta and the majority of patients with high-grade trochlear dysplasia demonstrated patellar apprehension that persisted beyond 60° of knee flexion. Additionally, 90% of patients with persistent apprehension had significant patella alta and/or trochlear dysplasia. Further work is needed to evaluate the utility of these findings to inform surgical decision-making in this population.

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The Presence of Patellar Apprehension in Higher Degrees of Flexion Identifies Patients with Patella Alta and or Severe Trochlear Dysplasia

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00345 ◽

2020 ◽

Vol 8 (7_suppl6) ◽

pp. 2325967120S0034

Author(s):

Matthew Colatruglio ◽

David Flanigan ◽

Sarah Harangody Robert Magnussen

Keyword(s):

Sports Medicine ◽

Knee Flexion ◽

Patellar Instability ◽

Trochlear Dysplasia ◽

Patella Alta ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Sulcus Angle ◽

Plain Films ◽

Recurrent Patellar Instability

Objectives: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle-trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as a tibial tubercle osteotomy or trochleoplasty. The indications to include such procedures are traditionally based on imaging criteria, but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. We hypothesis that the persistence of patellar apprehension at greater than 60 degrees of knee flexion is associated with patella alta, increased TT-TG distance, and trochlear dysplasia. Methods: Seventy-six patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeated assessed as the knee was flexed in 10 degrees intervals as measured with a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain films and MRI were obtained in all patients. Patellar height was assessed with the Caton-Deschamps (CD) index and trochlear morphology was assessed through measurement of the sulcus angle and depth on MRI and classification with the Dejour classification system. Imaging measurements of patients in which apprehension resolved by 60 degrees of knee flexion were compared with measures for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60 degrees of flexion in 55 patients and persisted into deeper flexion in 21 patients. The patients with delayed resolution of apprehension demonstrated a higher CD Index, elevated TT-TG distance, increased higher sulcus angle, decreased trochlear depth, and a higher incidence of Dejour B, C, or D dysplasia (all p < 0.05, Table 1). Of the 21 patients with delayed resolution of apprehension, 18 had either Dejour B, C, or D dysplasia or a Caton-Deschamps Index of at least 1.3. Delayed resolution of apprehension was present in 11 of the 16 patients with Dejour B, C, or D dysplasia. Conclusion: The presence of patellar apprehension in higher degrees of knee flexion is associated with patella alta, increased TT-TG distance, and more severe trochlear dysplasia. Further work is needed to evaluate utility of this exam finding to inform surgical decision-making in this population.

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Clinical Outcomes and Predictive Factors for Failure With Isolated MPFL Reconstruction for Recurrent Patellar Instability: A Series of 211 Reconstructions With a Minimum Follow-up of 3 Years

The American Journal of Sports Medicine ◽

10.1177/0363546519838405 ◽

2019 ◽

Vol 47 (6) ◽

pp. 1323-1330 ◽

Cited By ~ 22

Author(s):

Elliot Sappey-Marinier ◽

Bertrand Sonnery-Cottet ◽

Padhraig O’Loughlin ◽

Herve Ouanezar ◽

Levi Reina Fernandes ◽

...

Keyword(s):

Patellar Instability ◽

Trochlear Dysplasia ◽

Patella Alta ◽

Mpfl Reconstruction ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Kujala Score ◽

The Mean ◽

Recurrent Patellar Instability

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is widely acknowledged as an integral part of the current therapeutic armamentarium for recurrent patellar instability. The procedure is often performed with concomitant bony procedures, such as distalization of the tibial tuberosity or trochleoplasty in the case of patella alta or high-grade trochlear dysplasia, respectively. At the present time, few studies have evaluated the clinical effectiveness of MPFL reconstruction as an isolated intervention. Purpose: To report the clinical outcomes of isolated MPFL reconstruction in cases of patellar instability and to identify predictive factors for failure. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis of prospectively collected data was performed, including all patients who had undergone isolated MPFL reconstruction between January 2008 and January 2014. Preoperative assessment included the Kujala score, assessment of patellar tracking (“J-sign”), and radiographic features, such as trochlear dysplasia according to Dejour classification, patellar height with the Caton-Deschamps index (CDI), tibial tubercle–trochlear groove distance, and patellar tilt. The Kujala score was assessed postoperatively. Failure was defined by a postoperative patellar dislocation or surgical revision for recurrent patellar instability. Results: A total of 239 MPFL reconstructions were included; 28 patients (11.7%) were uncontactable and considered lost to follow-up. Thus, 211 reconstructions were analyzed with a mean follow-up of 5.8 years (range, 3-9.3 years). The mean age at surgery was 20.6 years (range, 12-48 years), and 55% of patients were male. Twenty-seven percent of patients had a preoperative positive J-sign, and 93% of patients had trochlear dysplasia (A, 47%; B, 25%; C, 15%; D, 6%). The mean CDI was 1.2 (range, 1.0-1.7); mean tibial tubercle–trochlear groove distance, 15 mm (range, 5-30 mm); and mean patellar tilt, 23° (range, 9°-47°). The mean Kujala score improved from 56.1 preoperatively to 88.8 ( P < .001). Ten failures were reported that required surgical revision for recurrent patellar instability (4.7%). Uni- and multivariate analyses highlighted 2 preoperative risk factors for failure: patella alta (CDI ≥1.3; odds ratio, 4.9; P = .02) and preoperative positive J-sign (odds ratio, 3.9; P = .04). Conclusion: In cases of recurrent patellar instability, isolated MPFL reconstruction would appear to be a safe and efficient surgical procedure with a low failure rate. Preoperative failure risk factors identified in this study were patella alta with a CDI ≥1.3 and a preoperative positive J-sign.

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Inter-rater reliability of TT-TG distance is good and does not vary based on preselected versus independent slice selection on MRI

Journal of ISAKOS Joint Disorders & Orthopaedic Sports Medicine ◽

10.1136/jisakos-2019-000306 ◽

2019 ◽

Vol 4 (6) ◽

pp. 302-305

Author(s):

Corey Beals ◽

David C Flanigan ◽

Nicholas Peters ◽

Walter Kim ◽

Nicholas Early ◽

...

Keyword(s):

Patellar Instability ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Level Of Evidence ◽

Rater Reliability ◽

Sulcus Angle ◽

Intraclass Correlations ◽

Good For ◽

Active Patients ◽

Axial Slice

ObjectivesPatellar instability is a frequent cause of knee dysfunction in young, active patients. Tibial tubercle–trochlear groove (TT-TG) distance, trochlear morphology (trochlear depth and sulcus angle) and patellar height are felt to contribute to patellar instability and may influence treatment. These measurements are frequently performed on MRI images. We hypothesised that inter-rater reliability of measures would be good and that inter-rater variation is driven primarily by slice selection.MethodsTwenty-six patients with at least one documented episode of patellar instability confirmed by MRI were identified. Six raters reviewed MRI images from each patient. Each rater measured and recorded TT-TG distance, trochlear depth and sulcus angle, and patellotrochlear index (PTI) for each patient and the slices used for the measurements. Each rater repeated the measurement using preselected slices. Inter-rater reliability was calculated by intraclass correlations (ICCs) for slice selection and for TT-TG distance, trochlear morphology measures and PTI with both independently selected and preselected slices. Statistically significant differences (p<0.05) in ICC based on slice selection were defined as values without overlap of their 95% CIs.ResultsInter-rater reliability was excellent for tibial (ICC=0.93) axial slice selection and sagittal slice selection (ICC=0.94), and good for femoral (ICC=0.88) axial slice selection. Using independent slice selection, inter-rater reliability was good for TT-TG distance (ICC=0.79) and fair for trochlear depth (ICC=0.57), sulcus angle (ICC=0.57) and PTI (ICC=0.71). When preselected slices were used, inter-rater reliability was good for TT-TG distance (ICC=0.85), sulcus angle (ICC=0.83) and PTI (ICC=0.77) and fair for trochlear depth (ICC=0.68). Only sulcus angle demonstrated a significant (p<0.05) improvement in inter-rater reliability with the use of preselected slices.Discussion and conclusionInter-rater reliability of TT-TG distance is good and does not vary based on preselected versus independent slice selection on MRI. Inter-rater reliability of trochlear morphology measures based on axial MRI slices and PTI is fair. Inter-rater variation can be reduced (particularly in the case of sulcus angle) through agreement on slice selection.Level of evidenceLevel III, diagnostic.

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ASSOCIATION BETWEEN RADIOGRAPHIC PARAMETERS AND OSTEOCHONDRAL DAMAGE IN PATIENTS WITH PATELLAR INSTABILITY

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00481 ◽

2020 ◽

Vol 8 (7_suppl6) ◽

pp. 2325967120S0048

Author(s):

Lilah Fones ◽

Regina Kostyun ◽

James Pace

Keyword(s):

Patellar Instability ◽

Trochlear Dysplasia ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Odds Ratios ◽

Sulcus Angle ◽

Radiographic Parameters ◽

Radiographic Measurements ◽

Patient Reported ◽

Adolescent Patients

Objectives: Osteochondral damage is a potential consequence of patellar instability that is associated with an increased risk of arthritis and lower patient reported outcomes. Currently, there is little evidence of risk factors associated with osteochondral damage in the setting of patellar instability. The purpose of this study was to identify the association of patient demographics, chronicity of patellar instability, and radiographic measurements with osteochondral damage in adolescent patients with patellar instability. Methods: Upon obtaining Institutional Review Board approval, a chart review was conducted to identify patients 18 years of age and younger treated for patellar instability between 2013 and 2018 at a tertiary referral center. Patients with both acute traumatic and chronic recurrent dislocations with magnetic resonance imaging (MRI) results available were included. Patients were excluded if they had a previous ipsilateral patellar instability surgical intervention. MRI exams were reviewed, and measurements were conducted for Caton-Deschamps (CD) ratio, proximal tibial tubercle to trochlear groove (pTT-TG), distal tibial tubercle to trochlear groove (dTT-TG), lateral trochlear inclination (LTI), lateral patellar inclination (LPI), and sulcus angle. Logistical regression was conducted using binary outcome of presence or absence of osteochondral damage (Statistical Analysis Software, Cary, NC). Odds ratios were calculated for parameters that were statistically significant (p<0.05). Results: A total of 129 knees and 122 patients (average age at first visit 14.4±3.0, 51% female) were identified with patellar instability, of which 53% had osteochondral damage. Approximately one third of patients (67%) were treated with surgical management. There was no association identified between osteochondral damage and sex, age, BMI, symptom duration, physeal status, or number of dislocation (acute vs chronic). Of the radiographic measurements evaluated, LTI, LPI, sulcus angle and dTT-TG all had a statistically significant association with the presence of osteochondral damage (Table 1). Every 1-unit decrease in LTI (more trochlear dysplasia) was associated with a 6% increased chance of osteochondral damage. Every 1-unit increase in LPI, sulcus angle, and dTT-TG is associated with an increased chance of osteochondral damage of 5.5%, 5.8%, and 11.3%, respectively. The CD ratio and pTT-TG had no association with osteochondral damage. Confidence intervals, p-values, and odds ratios are presented in Table 1. Conclusions: There is an association between radiographic parameters, particularly those that correlate with higher levels of trochlear dysplasia, and osteochondral damage in adolescent patients with patellar instability, but no association with being either an acute or chronic dislocator. Clinically, this may impact the management of patients presenting with patellar instability and no radiographic evidence of osteochondral damage. In these patients, clinicians may have a lower threshold for surgical interventions in those with higher levels of trochlear dysplasia as evidenced by decreased LTI and an increased LPI, sulcus angle, and dTT-TG.

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Trochlear dysplasia - congenital anomaly or biomechanical development

Medicinski pregled ◽

10.2298/mpns1804096t ◽

2018 ◽

Vol 71 (3-4) ◽

pp. 96-99

Author(s):

Zlatko Temelkovski ◽

Zoran Bozinovski ◽

Alan Andonovski ◽

Biljana Andonovska

Keyword(s):

Knee Flexion ◽

Patellar Instability ◽

Trochlear Dysplasia ◽

Breech Presentation ◽

Trochlear Groove ◽

Mechanical Theory ◽

Predisposing Factor ◽

Sulcus Angle ◽

Pathologic Findings ◽

The Mean

Introduction. The aim of this study was to investigate the appearance of the trochlear groove in infants and to present the possible causes for the development of trochlear dysplasia as one of the most severe pathologic findings in patients with patellar instability. Material and Methods. Knee ultrasonography was performed in 200 infants, 3 to 6 months of age. The measurements were made at 30 and 60 degrees of knee flexion, in order to measure the trochlear bone and cartilaginous sulcus angle on the patellar surface of the femur and to determine the degree of trochlear dysplasia. A 7-megahertz probe was used for measurements, which was tangentially placed with the reference to the posterior femoral joint. Results. A completely flat trochlear bony sulcus angle was registered in all infants aged 3 to 6 months. The mean cartilaginous sulcus angle was between 149 ? 5.4? and 19 infants had a sulcus angle over 159?. Eleven infants with trochlear dysplasia were in breech presentation at birth. Conclusion. Our study showed that the cartilaginous part of the trochlear groove was already well developed at birth. Breech presentation of the fetus could be a predisposing factor for dysplasia of the cartilaginous part of the trochlear groove. The bony part of the trochlear groove is dysplastic in infants and it gradually gets deeper, later getting a shape of the overlying articular cartilage. The influence of the Delpech law, with lower pressure in the trochlear groove, could be the possible mechanical theory explaining the development of the trochlear dysplasia in the later stage of the childhood.

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Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Regardless of the Tibial Tubercle Trochlear Groove Distance: Outcomes at 1 and 2 Years

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967118s00078 ◽

2018 ◽

Vol 6 (7_suppl4) ◽

pp. 2325967118S0007

Author(s):

Brandon J. Erickson ◽

Joseph Nguyen ◽

Katelyn Gasik ◽

Jacqueline Brady ◽

Beth E. Shubin Stein

Keyword(s):

Patellar Instability ◽

Medial Patellofemoral Ligament ◽

Trochlear Dysplasia ◽

Patellar Height ◽

Mpfl Reconstruction ◽

Tibial Tubercle ◽

Trochlear Groove ◽

One Year ◽

Recurrent Patellar Instability

Background: Several surgical options exist for treatment of recurrent patellar instability. The treatments can be divided into ligamentous and bony procedures. It is currently unclear which patients require a bony procedure in addition to a soft tissue reconstruction. Purpose: To report the one and two-year outcomes of patients following medial patellofemoral ligament (MPFL) reconstruction performed in isolation regardless of the patellar height, tibial tubercle trochlear groove distance (TT-TG) or trochlear dysplasia. Hypothesis:: Patients will have <5% re-dislocation rate and significant improvements in patient reported outcome measures (PROMs) following isolated MPFL reconstruction. Methods: All patients with recurrent patellar instability and without significant unloadable chondral defects, failed previous surgery or pain greater than or equal to 50% as their chief complaint, were prospectively enrolled beginning March of 2014. All patients underwent a primary, unilateral, isolated MPFL reconstruction regardless of concomitant bony pathology for treatment of recurrent patellar instability. Patients were followed at standard intervals. PROMs were collected at one year and two year follow up visits. Information on recurrent subjective instability, dislocations, and ability to return to sport (RTS) was recorded. TT-TG and patellar height (using the Caton-Deschamps index) were measured on magnetic resonance images. Results: Overall, 90 patients (77% female; average age 19.4 +/- 5.6 years) underwent a MPFL reconstruction from March 2014 to August 2017; 63 (70%) of whom reached one year follow up, and 35 of these patients (39%) reached 2-year follow-up. No patient experienced a redislocation; 96% of patients at one year and 100% of patients at two years had no subjective patellofemoral instability. RTS rates at one and two years were 59% and 75% respectively. No patient experienced a complication at one year. All patients had a clinically and statistically significant improvement from baseline to 1-year follow-up in the following PROMs: Knee injury and Osteoarthritis Outcome Score Quality of Life (KOOS QOL) (32.7 to 72.0; p<0.001), International Knee Documentation Committee (IKDC) (51.4 to 82.6; p<0.001) Kujala (62.2 to 89.5; p<0.001), and all general health PROM. No clinically and statistically significant change was seen between 1- and 2-year follow-ups in all outcome scores (all p>0.05). A non-statistically significant increase was seen in sporting activity of the Pediatric Functional Activity Brief Scale (Pedi-FABS) (13.9 to 16.7 p=0.292) at 2 years. Average patient satisfaction was 9.3 of 10 (10 being most satisfied) at 1- and 2-year follow-up. Average TT-TG was 15.1 +/- 4.0. Average patellar height was 1.25 +/- 0.17. Conclusion: Isolated MPFL reconstruction is an effective treatment for patellar instability and provides significant improvements in PROMs with a low redislocation/instability rate at early 1 and 2 year follow up, regardless of bony pathologies including TT-TG, Caton-Deschamps Index and trochlear dysplasia. The goal of this ongoing prospective study is to follow these patients out for 5 to 10 years to assess what radiologic and physical examination factors predict failure of isolated MPFL reconstruction.

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Isolated MPFL reconstruction for recurrent lateral patellar instability in patients with TT-TG distance <25 mm: A calculated safe risk!

Journal of Arthroscopic Surgery and Sports Medicine ◽

10.25259/jassm_22_2021 ◽

2021 ◽

Vol 0 ◽

pp. 1-7

Author(s):

Sumant Chacko Verghese ◽

Santosh K. Sahanand ◽

Nikhil Joseph Martin ◽

Abhay Harsh Kerketta ◽

Prashanth Chalasani ◽

...

Keyword(s):

Functional Outcome ◽

Patellar Instability ◽

Trochlear Dysplasia ◽

Treatment Algorithm ◽

Patella Alta ◽

Mpfl Reconstruction ◽

Long Term Results ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Study Population

Objectives: The objectives of the study were to describe the surgical technique of our modification of isolated medial patellofemoral ligament (MPFL) reconstruction, in patients with patellar instability. As per literature, isolated MPFL reconstruction is advocated if tibial tubercle-trochlear groove (TTTG) <20 mm. Our study proposes isolated MPFL reconstruction in patients with TT-TG <25 mm and aims to determine any predisposing anatomic variants to aid in the treatment algorithm. Materials and Methods: A retrospective analysis of 52 patients with patellar instability (TT-TG <25 mm), who underwent isolated MPFL reconstruction was undertaken. The study population was divided into two groups; TT-TG <20 mm and TT-TG = 20–24 mm. Both groups were assessed radiologically and on the basis of clinical and functional outcome (KUJALA score), over 5-year follow-up period. Results: The mean age of the study population was 21.98 years, with a female (63.5%) majority. Among the 52 patients included in the study, 39 patients (75%) had TT-TG <20 mm and 13 patients (25%) had TT-TG = 20–24 mm. We noticed statistically significant improvement in both groups with respect to clinical and functional outcome, with no reported complications. None of the patients had patella alta or high grades of trochlear dysplasia. Conclusion: MPFL reconstruction without concomitant bony procedures can be safely performed in patients with a TT-TG <25 mm, in the absence of patella alta or high-grade trochlear dysplasia. Our modification of isolated MPFL reconstruction has shown excellent long-term results. In addition, our technique uses only a single interference screw, thereby reducing cost of surgery and implant hardware.

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Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Regardless of Tibial Tubercle–Trochlear Groove Distance and Patellar Height: Outcomes at 1 and 2 Years

The American Journal of Sports Medicine ◽

10.1177/0363546519835800 ◽

2019 ◽

Vol 47 (6) ◽

pp. 1331-1337 ◽

Cited By ~ 15

Author(s):

Brandon J. Erickson ◽

Joseph Nguyen ◽

Katelyn Gasik ◽

Simone Gruber ◽

Jacqueline Brady ◽

...

Keyword(s):

Patellar Instability ◽

Medial Patellofemoral Ligament ◽

Trochlear Dysplasia ◽

Patellar Height ◽

Mpfl Reconstruction ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Outcome Scores ◽

Recurrent Patellar Instability

Background: It is unclear which patients with recurrent patellar instability require a bony procedure in addition to medial patellofemoral ligament (MPFL) reconstruction. Purpose: To report 1- and 2-year outcomes of patients after isolated MPFL reconstruction performed for patellar instability regardless of patellar height, tibial tubercle–trochlear groove (TT-TG) distance, or trochlear dysplasia. Study Design: Case series; Level of evidence, 4. Methods: All patients with recurrent patellar instability and without significant unloadable chondral defects (Outerbridge grade IV), cartilage defects (especially inferior/lateral patella), previous failed surgery, or pain >50% as their chief complaint were prospectively enrolled beginning March 2014. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of concomitant bony pathology for treatment of recurrent patellar instability. Information on recurrent subjective instability, dislocations, ability to return to sport (RTS), and outcome scores was recorded at 1 and 2 years. TT-TG distance, patellar height (with the Caton-Deschamps index), and trochlear depth were measured. Results: Ninety patients (77% female; mean ± SD age, 19.4 ± 5.6 years) underwent MPFL reconstruction between March 2014 and August 2017: 72 (80%) reached 1-year follow-up, and 47 (52.2%) reached 2-year follow-up (mean follow-up, 2.2 years). Mean TT-TG distance was 14.7 ± 5.4 mm (range, –2.2 to 26.8 mm); mean patellar height, 1.2 ± 0.11 mm (range, 0.89-1.45 mm); and mean trochlear depth, 1.8 ± 1.4 mm (range, 0.05-6.85 mm). Ninety-six percent of patients at 1 year and 100% at 2 years had no self-reported patellofemoral instability; 1 patient experienced a redislocation at 3.5 years. RTS rates at 1 and 2 years were 90% and 88%, respectively. Mean time to RTS was 8.8 months. All patients had clinically and statistically significant improvement in mean Knee injury and Osteoarthritis Outcome Score–Quality of Life (32.7 to 72.0, P < .001), mean International Knee Documentation Committee subjective form (51.4 to 82.6, P < .001), and mean Kujala score (62.2 to 89.5, P < .001). No difference existed between 1- and 2-year outcome scores (all P > .05). Conclusion: At early follow-up of 1 and 2 years, isolated MPFL reconstruction is an effective treatment for patellar instability and provides significant improvements in outcome scores with a low redislocation/instability rate regardless of bony pathologies, including TT-TG distance, Caton-Deschamps index, and trochlear dysplasia. Future data from this cohort will be used to assess long-term outcomes.

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Bisect offset ratio and cartilaginous sulcus angle are good combined predictors of recurrent patellar dislocation in children and adolescents

Journal of ISAKOS Joint Disorders & Orthopaedic Sports Medicine ◽

10.1136/jisakos-2020-000461 ◽

2021 ◽

pp. jisakos-2020-000461

Author(s):

Sheanna Maine ◽

Christina Ngo-Nguyen ◽

Martina Barzan ◽

Chris Stockton ◽

Luca Modenese ◽

...

Keyword(s):

Patellar Dislocation ◽

Trochlear Dysplasia ◽

Pediatric Population ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Recurrent Patellar Dislocation ◽

Patellar Tilt ◽

Level Of Evidence ◽

Femoral Torsion ◽

Sulcus Angle

ObjectivesRecurrent patellar dislocation (RPD) is found most commonly in the juvenile population. While risk factors have been well-established in adults, there remains a paucity in radiographical data to define normal and pathoanatomical juvenile cohorts. The objectives of this paper were to elucidate the differences in the patellofemoral joint between RPD and typically developed (TD) juvenile populations, using MRI measurements, and determine the best independent and combined predictors of RPD.MethodsA prospective, cross-sectional study was conducted with 25 RPD and 24 TD participants aged between 8 and 19 years. MR images were obtained to assess common measures of lower limb alignment, patellofemoral alignment, and trochlear dysplasia.ResultsSignificant differences were evident for acetabular inclination, tibial-femoral torsion, tibial tubercle-to-trochlear groove (TT-TG) distance, lateral patellar tilt (LPT), cartilaginous sulcus angle (CSA) and bisect offset ratio (BOR). CSA and BOR were included in the final predictive model, which correctly classified 89.4% of RPD cases.ConclusionRadiographical parameters that stratify risk of RPD in adults are also able to predict RPD in the pediatric population (TT-TG, LPT, CSA and BOR). Together, CSA and BOR accurately identified 89.4% of RPD. These measures should be included in the evaluation of pediatric patients who present with patellar dislocation.Level of evidenceLevel II.

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