Arthroscopic Medial Patellofemoral Ligament Insertion Reconstruction and Plication for Medial Patellar Retinaculum Using Suture Anchor in First Acute Patellar Dislocation

Background: The objective of this study was to evaluate the clinical results of arthroscopic medial patellofemoral ligament (MPFL) insertion reconstruction and plication for medial patellar retinaculum using suture anchor combined with lateral retinacular release in first acute patellar dislocation (APD) with MPFL insertion injury in adolescents.Methods: A prospective study was performed between January 2016 and July 2019. The series included 61 cases of adolescent patients with first APD. There were 7 males and 54 females with an average age of 15.5 years (10 to 22). All cases were treated with arthroscopic suture anchor plication for medial patellar retinaculum combined with lateral retinacular release. Congruence angle (CA), lateral patellar angle (LPA), and patellar tilt angle (PTA) are measured by CT scan between last follow-up and preoperative. In addition, the patients were evaluated with the Lysholm and Kujala scores.Results: The average follow-up time was 40.9 months (24-60 months). All 61 knees showed excellent or good results postoperatively. The Lysholm score increased significantly from 58.6±8.1 to 91.9±5.0 at the last follow-up postoperatively (P<0.001 ). The Kujala scores increased significantly from 60.4±7.3 to 88.9±4.8 at the last follow-up postoperatively (P < 0.001). CA in 0° extension position was improved significantly from 19.8±2.1° preoperatively to -6.7±1.7° at the last follow-up (P<0.001), LPA was increased from -7.4±2.2° to 5.7±1.8° (P<0.001), and PTA was increased from 23.8±2.9° to 12.3 ±2.3° (P<0.001). The postoperative mean Lysholm and Kujala scores were 91.9 (81–100) and 88.9 (79–100), respectively.Conclusions: When the first APD occurs associated with the MPFL avulsed from the patella, the presented technique could not only reattach MPFL at the patellar border but also strengthen the medial patellar retinaculum. This anatomical repair technique can significantly improve the stability of the patella and has the advantage of being less invasive by the full-arthroscopic approach.

1053 Comparing MRI Parameters in Quantifying Patellofemoral Instability

Aim Patellofemoral instability is where various stabilising factors of the patellofemoral joint undergo pathomorphological changes. It has an incidence rate of 5.8 per 100,000 in UK and has been associated with osteoarthritis[1]. Variations in the factors that stabilise the patellofemoral joint can be observed on MRI including measurements of the trochlea in relation to the patella, the femur and soft tissue changes. This study aims to compare different measures used to detect and quantify patellofemoral instability on MRIs and to look for any significant difference in their use both in isolation and together. Method 109 MRI reports of 78 patients diagnosed with patellofemoral instability were reviewed and all quantitative and qualitative parameters reported were inputted in a data table. Quantitative elements known as the Dejour protocol included the trochlear sulcus angle, patellar tilt angle, tibial tuberosity-trochlear groove distance and the Insall-Salvati ratio. Qualitative factors involved facet changes, patellar position, and any damage to soft tissue. Results It was found that the Insall-Salvati ratio greater than 1.2 and the patellar tilt angle of greater than 11 degrees irregular ranges had the greatest incidence in the MRI reports found 77.1% and 87.6% respectively in MRIs that reported them. Conclusions There is a discrepancy between quantitative parameters in their correlation with patellofemoral instability for the MRI reports observed. [1]: Ye Q, Yu T, Wu Y, Ding X, Gong X. Patellar instability: the reliability of magnetic resonance imaging measurement parameters. BMC Musculoskeletal Disorders. 2019;20(1).

Comparison of the Radiologic, Morphometric, and Clinical Outcomes between Kinematically and Mechanically Aligned Total Knee Arthroplasty: A Propensity Matching Study

The purpose of this study was to compare radiologic, morphometric, and clinical outcomes between kinematically aligned (KA) and mechanically aligned (MA) total knee arthroplasty (TKA) in Korean patients. Overall, 168 patients who underwent primary TKA were retrospectively reviewed, and propensity matching (age, sex, and body mass index) was performed as 1:3 ration (KA TKAs [n = 42]: MA TKAs [n = 126]). Joint-line orientation angle (JLOA), coronal and axial alignments of implants, hip–knee–ankle (HKA) angle, and patellar tilt angle were assessed using full-length standing radiograph, axial computed tomography (CT) scan, and plain radiographs. Morphometric assessment was performed by analyzing the intraoperative measurement of the femoral cut surface and femoral components fitting in five zones. Clinical outcomes more than 2 years of follow-up were evaluated with the Knee Society (KS) knee and functional scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and the Short-Form Health Survey (SF-36). In radiologic results, JLOA was more parallel to the floor in KA TKAs (KA: medial tilt 0.9 ± 1.5 degrees; MA: lateral tilt 1.7 ± 1.5 degrees, p < 0.05), and patellar tilt angle was closer to preoperative status after KA TKA (KA: 2.0 ± 1.6 degrees; MA;0.3 ± 1.2 degrees, p < 0.05). HKA angle and rotational mismatch were similar between two groups. In morphometric analysis, entire overhang of anterior femoral cutting surface was reduced in KA TKA compared with MA TKA (KA: 11.7 ± 6.2 mm; MA: 14.4 ± 5.9 mm, p < 0.05). However, both of MA and KA TKAs showed underhang in mediolateral dimension without difference. There were no significant differences in clinical scores between two groups. KA TKA showed more parallel JLOA to floor, closer patellar tilt to preoperative status, and better anterior flange fitting that can reproduce more natural knee kinematics compared with MA TKA. Although clinical outcomes assessed by conventional evaluating tools were similar between two groups, further evaluation focusing on the patellofemoral symptoms or unawareness of TKA is necessary to clarify the clinical benefit of KA TKA.

Relationship of Patellofemoral Angles and Tibiofemoral Rotational Angles With Jumper’s Knee in Professional Dancers: An MRI Analysis

Background: Jumper’s knee is a type of tendinopathy affecting the distal insertion of the quadriceps tendon (25% of cases) or the patellar tendon. It has been shown that frontal-plane measurements, such as genu valgum, genu varum, an increased quadriceps angle, a protuberant tibial tuberosity, patella alta, and short hamstring muscles, may be related to jumper’s knee. Purpose: To investigate the effects of tibiofemoral rotational angles and patellofemoral (PF) angles on the development of jumper’s knee in professional folk dancers. Study Design: Case-control study; Level of evidence, 3. Methods: We examined 26 dancers (16 male, 10 female) with knee pain using magnetic resonance imaging (MRI), for a total of 32 knees. Of the knees, 21 with quadriceps tendinopathy (QT) and 7 with patellar tendinopathy (PT) were detected. Using MRI scans, we measured PF angles (PF sulcus angle, lateral PF angle, patellar tilt angle, lateral trochlear inclination angle, lateral patellar tilt angle, and PF congruence angle) and tibiofemoral rotational angles (condylar twist angle, posterior condylar angle, femoral Insall angle, tibial Insall angle, posterior tibiofemoral angle, and angle between the Whiteside line and posterior femoral condylar line) and noted specifics such as patella alta, patella baja, and the Wiberg classification of the patellar shape between the patients with versus without QT and between patients with versus without PT to understand if there was any relationship with tendinopathy. Results: No statistically significant difference was observed in age, sex, patella alta, or the Wiberg classification between the QT groups (with vs without) and between the PT groups (with vs without) ( P > .05). Having QT was found to be significantly associated with the PF sulcus angle ( P = .009), and having PT was found to be significantly associated with the femoral Insall angle ( P = .029). Conclusion: Jumper’s knee was found to be associated with anatomic variations of the PF sulcus angle and rotation of the patellar tendon in relation to the femur (femoral Insall angle) on axial MRI scans in professional dancers. Unlike those of other athletes, dancers’ knees are exposed more to external rotation forces because of turnout, and this can be the cause of jumper’s knee.

Comparison of Clinical and Radiological Outcomes Between Transosseous Tunnel and Suture Anchor Patellar Fixation for Medial Patellofemoral Ligament Reconstruction: A Cohort Study With 2-Year Follow-up

Background: Several surgical methods have been developed for medial patellofemoral ligament reconstruction (MPFLR). However, the question of which patellar fixation method, suture anchor (SA) or transosseous tunnel (TO) fixation, achieves better overall outcomes remains to be answered. Hypothesis: SA patellar fixation will present comparable clinical outcomes and a lower complication rate compared with TO patellar fixation for MPFLR. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively reviewed the outcomes of 46 patients who underwent MPFLR with either TO fixation (n = 21; mean age, 24.4 ± 6.1 years) or SA fixation (n = 25; mean age, 24.1 ± 12.1 years) for the treatment of recurrent patellar dislocation. Clinical findings (International Knee Documentation Committee [IKDC] subjective score, Lysholm score, and Tegner activity score), radiological findings (congruence angle and patellar tilt angle), and complications (redislocation, patellar fracture, patellofemoral osteoarthritis progression, infection, and stiffness) were compared between the TO and SA groups at the 2-year follow-up visit. Results: The mean postoperative IKDC subjective and Lysholm scores did not differ significantly between groups. However, postoperative Tegner activity scores were significantly higher in the TO group than in the SA group (TO, 5.8 ± 1.4; SA, 4.9 ± 1.2; P = .012). Congruence angle did not differ significantly between the groups (TO, −3.2 ± 22.8; SA, −7.6 ± 17.8; P = .464). Patellar tilt angle was lower in the TO group than in the SA group (TO, 10.5 ± 5.4; SA, 13.7 ± 2.8; P = .015). During the follow-up period, the TO group had 1 redislocation and 2 patellar fractures, whereas the SA group had no redislocations or fractures. Patellofemoral osteoarthritis progression was significantly higher in the TO group than in the SA group at the 2-year follow-up visit (TO, 9/21; SA, 2/25; P = .006). Conclusion: Both TO and SA patellar fixation methods for MPFLR showed improved clinical outcomes. When compared with TO fixation, SA fixation presented comparable clinical outcomes and a lower complication rate.

Relation of the chondromalatia patellae to proximal tibial anatomical parameters, assessed with MRI

BackgroundMagnetic resonance imaging (MRI) is a non-invasive highly sensitive tool for diagnosing chondromalacia patellae in the early stages. Many studies have evaluated patellar and trochlear morphology with different radiologic indices. We aimed to assess the discriminative power of tibial, patellar, and femoral indices in MRI for chondromalacia patellae.Patients and methods100 cases of chondromalacia, as well as 100 age-matched controls among the patients who underwent knee MRI between February 2017 and March 2019, were included. The standard protocol of knee MRI was applied and the diagnosis of chondromalacia was made on MRI findings. Chondromalacia subjects were also classified as grade 1 to 4 according to the Modified Outerbridge’s MRI grading system. We measured 25 MRI parameters in the knee and adjacent structures to determine the relation between chondromalacia patellae and anatomical MRI parameters.ResultsTibial slope, trochlear depth, lateral trochlear inclination, and lateral patellar tilt angle had significant correlation with chondromalacia. Any increase in lateral trochlear inclination and lateral patellar tilt angle could increase the probability of the disease (Odds ratio [OR] 1.15, 1.13; 95% CI: 1.03–1.30; 1.02–1.26, respectively), while any increase in medial tibial slope and trochlear depth could decrease the probability of chondromalacia (OR 0.85, 0.06; 95% CI: 0.73–0.98, 0.02–0.17, respectively). We also designed a model for the severity of disease by using the patellar height index (relative odds ratio: 75.9).ConclusionsThe result of this study showed the novelty role of tibial anatomy in developing chondromalacia and its mechanism. We also concluded that patellar height might be an important factor in defining disease severity.

Clinical Outcomes After Medial Patellofemoral Ligament Reconstruction With Suture Fixation of the Gracilis Tendon via Transosseous Tunnels

Background: Several fixation methods have been introduced in medial patellofemoral ligament (MPFL) reconstruction. However, the optimal management of patients with recurrent patellar dislocation remains controversial. Purpose: To present a case series with a minimum 2-year follow-up of 29 patients with recurrent patellar dislocation who underwent a new transosseous suture fixation technique for MPFL reconstruction. Study Design: Case series; Level of evidence, 4. Methods: From January 2014 through February 2016, a total of 29 patients with recurrent patellar dislocation for which the MPFL was reconstructed with transosseous suture patellar fixation were studied. All patients were available for follow-up (mean, 37.52 months; range, 26-48 months). The patellar attachment was fixed by transosseous patellar sutures. The International Knee Documentation Committee (IKDC) subjective knee score, Kujala score, Tegner score, range of motion, congruence angle, patellar tilt angle, and complications were assessed both pre- and postoperatively. Results: No recurrent dislocation was observed in any of the 29 patients for a minimum of 2 years. All outcome scores improved significantly from preoperatively to postoperatively: the average IKDC subjective knee evaluation score from 53 to 87, Kujala from 54 to 90, Lysholm from 50 to 89, and Tegner from 3 to 5 ( P < .001 for all). The congruence angle significantly decreased from 22° preoperatively to –3° postoperatively, and the patellar tilt angle (Merchant) decreased from 23° preoperatively to 5° postoperatively ( P < .001 for both). In total, 25 patients (25/29; 86.21%) were completely pain-free when performing activities of daily living at the last follow-up, and 27 patients (93.1%) rated themselves as very satisfied or satisfied with the results. Conclusion: In patients with chronic recurrent patellar dislocation, transosseous patellar suture fixation for MPFL reconstruction can significantly improve patellar stability and achieve good results at short-term follow-up.

Automatic Segmentation and Measurement on Knee Computerized Tomography Images for Patellar Dislocation Diagnosis

Traditionally, for diagnosing patellar dislocation, clinicians make manual geometric measurements on computerized tomography (CT) images taken in the knee area, which is often complex and error-prone. Therefore, we develop a prototype CAD system for automatic measurement and diagnosis. We firstly segment the patella and the femur regions on the CT images and then measure two geometric quantities, patellar tilt angle (PTA), and patellar lateral shift (PLS) automatically on the segmentation results, which are finally used to assist in diagnoses. The proposed quantities are proved valid and the proposed algorithms are proved effective by experiments.

Anatomical Medial Patellofemoral Ligament Reconstruction for Recurrent Patella Dislocation: Two-Strand Grafts versus Four-Strand Grafts

The purpose of this study was to describe two anatomical medial patellofemoral ligament (MPFL) reconstruction methods: reconstruction with two-strand grafts and reconstruction with four-strand grafts and to evaluate the clinical and radiological results. From January 2010 to January 2013, patients who sustained recurrent patella dislocation and met inclusion criteria were included in the study and divided into two groups randomly to undergo MPFL reconstruction either by two-strand grafts (T group) or four-strand grafts (F group). Patients were followed up 1 month, 1 year, 2 years, and 3 years postoperatively. The apprehension test was applied to test patella stability. The Kujala score, Lysholm score, and Crosby–Insall grading were used to evaluate the function of the affected knee. The patellar congruence and patellar tilt angle were used to measure the morphology of the patellofemoral joint. In addition, patients' subjective assessments and complications were recorded. Thirty-eight patients in T group and 38 patients in F group were followed for at least 36 months. The apprehension test was positive in all patients preoperatively but was negative at follow-up. The Kujala score, Lysholm score, patellar congruence angle, and the patellar tilt angle of patients in both groups improved significantly at 36-month follow-up when compared with those assessed preoperatively. However, patients in the F group achieved better clinical results in terms of Kujala score, patellar congruence angle, patellar tilt angle, and Crosby–Insall grading when compared with those in the T group 3 years after the operation. Most patients (92% of patients in the T group and 97% of patients in the F group) were satisfied with the surgery. The anatomical MPFL reconstruction with two-strand grafts or four-strand grafts were both safe techniques for recurrent patella dislocation with satisfactory clinical outcomes. The anatomical fixation with four-strand grafts achieved better clinical and radiographic results in the follow-up, which may be a better reconstruction method.