Recurrent Patellar Dislocation Research Articles

Surgical treatment for recurrent patellar dislocation with severe torsional deformities:Double-level derotational osteotomy may not have a clear advantage over single-level derotational osteotomy in improving clinical and radiological outcomes.

The purpose of this study was toinvestigate whether double-level (femur + tibia) derotational osteotomy is superior to single-level femoral derotational osteotomy for recurrent patellar dislocation with severe femoral and tibial rotational deformities (femoral anteversion >30° and external tibial torsion >30°). Between January 2015 and June 2020, a total of 115 knees with recurrent patellar dislocation treated with combined medial patellofemoral ligament reconstruction (MPFL-R) and derotational osteotomies were evaluated after a minimum follow-up of 2 years. Among these cases, 15 knees that underwent double-level derotational osteotomy were included in the double-level group, which was propensity-matched in a 1:2 ratio to a single-level group of patients who underwent single-level femoral derotational osteotomy (30 knees). The clinical and radiological outcomes were evaluated and compared between the groups. Furthermore, the foot progression angle was measured preoperatively and 2 years after surgery. The patient-specific variables did not differ significantly between the double-and the single-level groups after propensity score matching. The postoperative mean foot progression angle was significantly lower in the double-level groupthan in the single-level group (9° ± 8° vs. 15° ± 11°; p = 0.014); however, there were no statistically significant differences between the groups in terms of any other clinical and radiological assessments. For patients with severe femoral and tibial torsional deformities (femoral anteversion >30° and external tibial torsion >30°), the double-level derotational osteotomy is superior to single-level osteotomy in maintaining normal foot progression angle, but it does not show an advantage in terms of patient-reported outcomes, radiological resultsand redislocation rate at minimum 2 years of follow-up. Furthermore, concomitant excessive external tibial torsion (>30°) did not have an adverse effect on clinical outcomes in patients who underwent derotational distal femoral osteotomy with MPFL-R due to excessive femoral anteversion. Level III.

Single Versus Double Tunnel Fixation in Medial Patellofemoral Ligament Reconstruction: A Meta-Analysis.

The purpose of this meta-analysis was to conduct a comparative analysis of clinical scores and complication rates among patients experiencing recurrent patellar dislocation who underwent medial patellofemoral ligament (MPFL) reconstruction using both single and double tunnel techniques. A comprehensive search was conducted across electronic databases including PubMed, the Cochrane Library, Web of Science, and Google Scholar to retrieve articles relevant to MPFL reconstruction utilising the tunnel technique. Subsequently, meta-analyses were undertaken to assess complication rates and changes in clinical scores before and after surgery. Following this, sensitivity analysis and meta-regression analysis were performed to scrutinise potential confounding variables. A total of thirty-two studies were included in the analysis, comprising twenty-seven non-comparative studies and five comparative studies. The findings revealed a similarity in postoperative complication rates between the single and double tunnel fixation techniques: [9.0% (95%CI, 4.0%-15.6%) versus 8.9% (95%CI, 4.7%-14.1%, p = 0.844)]. Likewise, no statistically significant differences were observed in Lysholm scores [34.1 (95%CI, 26.7-41.5) versus 33.8 (95%CI, 27.7-40.0, p = 0.956)], Kujala scores [29.4 (95%CI, 22.3-36.4) versus 27.3 (95%CI, 22.3-32.3, p = 0.637)], and Tegner score change [1.1 (95%CI, 0.8-1.4) versus 0.7 (95%CI, -0.2-1.6, p = 0.429)] before and after MPFL reconstruction, respectively, using these two techniques. In conclusion, the authors found that the clinical functional improvement and complication rates in MPFL reconstruction using the single tunnel fixation technique are comparable to those achieved with the double tunnel fixation approach. However, to further advance the understanding in this field, additional randomised controlled studies must be conducted to provide further insights. Key Words: MPFL reconstruction, Bone tunnel, Patellar dislocation, Meta-analysis.

Recurrent patellar dislocation patients with high-grade J-sign have multiple structural bone abnormalities in the lower limbs.

To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD). A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ2 test was used to compare composition ratio differences of structural bone abnormalities among the groups. A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001). In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures. Level III.

Derotational distal femur osteotomy with medial patellofemoral ligament reconstruction can get good outcomes in the treatment of recurrent patellar dislocation with excessive TT-TG and increased femoral anteversion.

Surgery is the main treatment for recurrent patellar dislocation (PD). However, due to the complexity of anatomical factors, there is still a lack of consensus on the choice of combined surgical methods. This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction combined with derotational distal femur osteotomies (MPFLR + DDFO) and combined with tibial tubercle osteotomies (MPFLR + TTO) for recurrent PD with increased femoral anteversion angles (FAA) and excessive tibial tubercle-trochlear groove (TT-TG) distance. In this retrospective analysis, MPFLR + DDFO and MPFLR + TTO patients from 2015 to 2020 were included. Group A (MPFLR + DDFO, n = 42) and B (MPFLR + TTO, n = 46) were formed. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), visual analog scale (VAS) and intermittent and persistent osteoarthritis pain scale (ICOAP), Tegner scores), and complications. The Caton-Deschamps index (CD-I), patellar title angle, patellar congruence angle, patella-trochlear groove distance, TT-TG distance, and FAA were used to assess radiological outcomes. All clinical outcomes improved significantly in both groups, but Group A had significantly better postoperative scores than Group B (Kujala: 89.8 ± 6.4 vs. 82.9 ± 7.4, P < 0.01; Lysholm: 90.9 ± 5.1 vs. 81.3 ± 6.3, P = 0.02; IKDC: 87.3 ± 9.0 vs. 82.7 ± 8.0, P < 0.01; Tegner: 6.0 (5.0, 9.0) vs. 5.0 (4.0, 8.0), P = 0.01). However, there was no significant difference in the VAS and ICOAP scores between the two groups. No dislocation recurrences occurred. Radiological outcomes improved significantly in both groups, but Group A had better outcomes. After surgery, the patellar height of 88.5% (23/26) patients in Group A and 82.8% (24/29) patients in Group B was restored to normal (the Caton-Deschamps index <1.2). Both MPFLR + TTO and MPFLR + DDFO obtained satisfactory clinical and radiological outcomes in the treatment of recurrent PD with increased FAA and excessive TT-TG. However, the outcomes of MPFLR + DDFO were better and should be considered a priority. MPFLR + TTO may be not necessary for such patients.

Identification of eight genes associated with recurrent patellar dislocation

The inheritance of recurrent patellar dislocation (RPD) is known, but the susceptible gene remains unidentified. Here, we performed the first whole exome sequencing (WES) cohort study to identify the susceptible genes. The results showed eight genes were associated with this disease. Notably, the carboxypeptidase D (CPD) gene showed the highest relevance based on its gene function and tissue expression. Single-cell sequencing results indicate that the CPD gene is involved in the pathophysiological process of RPD through granulocytes. Implicated pathways include nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and Wnt/β-catenin signaling, potentially influencing CPD's role in RPD pathogenesis. This study identified the susceptible gene and investigates the potential pathogenesis of RPD, which provided a new prospect for the understanding of RPD. Besides, it would offer the theoretical basis for disease prevention and genetic counseling.

Diagnosis and treatment of recurrent patellar dislocation with knee extensor device combined with rearrangement.

This study aimed to investigate the clinical effects of combining knee extension mechanism (EM) with rearrangement in the treatment of recurrent patellar dislocation (RPD). Eighty-four patients with RPD admitted to the First Affiliated Hospital of Kunming Medical University were included. In this work, all patients received routine computed tomography (CT) examinations. In addition, the evaluation factors of EM combined with rearrangement therapy in RPD patients were analyzed using logistic regression. Lysholm and Kujula scores, femoral canal width, patellar canal width, patellar tilt angle (PTA), and lateral patellar displacement (LPD) were significantly increased at 1 and 3 years after treatment (p < 0.05). LPA was significantly decreased, while the tibial tuberosity trochlear groove of the femur (TT-TG) demonstrated no considerable differences (p > 0.05). The good rate of the short-term Insall-Salvati index was 78.6%, and that of the long-term Insall-Salvati index was 76.1%. The combination of the knee extension device and rearrangement therapy has a higher rate of short-term and long-term Insall-Salvati index (ISI) excellence. In addition, the range of motion of the knee joint increased significantly, and the Q Angle decreased significantly (p < 0.05). Logistic regression analysis showed that age and ISI were highly correlated with the evaluation of therapeutic effects in patients with RPD. EM combined with rearrangement in the treatment of RPD had positive short-term and long-term efficacy, high application value, and age, which can be popularized in clinical applications and have positive diagnostic value.

The Morphologic Patella Entry Point Into The Proximal Trochlea Is More Lateral in Recurrent Dislocators Than Controls as Measured by Entry Point-Trochlear Groove Angle

PurposeThe purpose of this work is to create a metric for evaluating the degree of laterality of the patella’s entry into the trochlea, the entry point-trochlear groove (EP-TG) angle, and to evaluate if this laterality is associated with recurrent patella instability. MethodsThe time frame of the study was January 2020 to February 2023. The inclusion criteria were patients treated by the senior author (JPF) (with the exception of two patients who were treated by another provider at the institution who was aware of the study) who have been diagnosed with recurrent atraumatic patellar dislocations. Controls without knee pathology were selected from the New Mexico Decedent Imaging Database (NMDID). Simpleware ScanIP was used to create three-dimensional (3D) models of the distal femurs from CT scans. AP images of these 3D models were uploaded to a custom EP-TG angle measuring tool. Three measurers used the tool to measure the EP-TG angle of the distal femurs. Results28 patients were included for the recurrent dislocator group. 24 decedents from NMDID were selected for the control group, each with a left or right knee chosen randomly for measurement. A one-sided Mann-Whitney U test, used to evaluate whether the recurrent dislocators had higher EP-TG angle values, yielded a p value <0.001, demonstrating a high level of significance. A Bayesian mixed effect model, used to determine how different the EP-TG angles are between the two groups, gave a posterior predictive interval (PPI) of [11.93, 19.12] degrees for the EP-TG angle shift of dislocators. The intraclass correlation coefficient was 0.648. ConclusionsThe morphological entry point of the patella into the proximal trochlea is more lateral in recurrent patella dislocators than in controls. This increased laterality can be measured by EP-TG angle, which may be useful information for optimizing treatment of recurrent patella instability. Level of EvidenceLevel III Case Control Study

The Importance of Medial Patellar Shape as a Risk Factor for Recurrent Patellar Dislocation in Adults

Background: Research on the cause of lateral patellar dislocation (LPD) has focused on trochlear morphologic parameters, joint alignment, and patellofemoral soft tissue forces. A paucity of information is available regarding how patellar morphologic parameters influence the risk for LPD. Purpose/Hypothesis: The purpose was to assess whether patellar morphology is a risk factor for recurrent LPD. It was hypothesized that (1) patients with recurrent LPD would have decreased patellar width and volume and (2) patellar morphologic parameters would accurately discriminate patients with recurrent LPD from controls. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 21 adults with recurrent LPD (age, 29.7 ± 11.1 years; height, 170.8 ± 9.9 cm; weight, 76.1 ± 17.5 kg; 57% female) were compared with 21 sex- and height-matched controls (age, 27.2 ± 6.7 years; height, 172.0 ± 10.6 cm; weight, 71.1 ± 12.8 kg; 57% female). Three-dimensional axial fat-saturated magnetic resonance imaging scans were used to measure patellar medial, lateral, and total width; patellar volume; patellar medial and lateral facet length; the Wiberg index; and previously validated knee joint alignment and femoral shape measurements (eg, tibial tuberosity to trochlear groove distance, trochlear dysplasia). Results: The LPD group demonstrated reduced medial patellar width (Δ = −3.6 mm; P < .001) and medial facet length (Δ = −3.7 mm; P < .001) but no change in lateral width or facet length. This resulted in decreased total patellar width (Δ = −3.2 mm; P = .009), decreased patellar volume (Δ = −0.3 cm3; P = .025), and an increased Wiberg index (Δ = 0.05; P < .001). No significant differences were found for all other patellar shape measures between cohorts. Medial patellar width was the strongest single discriminator (83.3% accuracy) for recurrent LPD. Combining medial patellar width, patellofemoral tilt, and trochlear groove length increased the discrimination to 92.9%. Conclusion: The medial patellar width was significantly smaller in patients with recurrent LPD and was the single most accurate discriminator for recurrent LPD, even compared with traditional trochlear shape and joint alignment measures (eg, trochlear dysplasia, patella alta). Therefore, medial patellar morphology should be assessed in patients with LPD as a risk factor for recurrence and a potential means to improve treatment.

Impact of sex and age on the lateralisation of the tibial tubercle in normal paediatric and adolescent populations.

Numerous methods have been proposed to characterise tubercle lateralisation. However, their normal values and related changes remain unclear. Accordingly, it was aimed to determine the potential sex and age effects and determined the optimal individualised method of diagnosing lateralisation of the tibial tubercle in patients with recurrent patellar dislocation (RPD). Measurements included the tibial tubercle-trochlear groove (TT-TG) distance, tibial tubercle-posterior cruciate ligament (TT-PCL) distance and tibial tubercle lateralisation (TTL); and the proximal tibial width (PTW), trochlear width (TW) and trochlear dysplasia index (TDI), for adjustment. A two-way analysis of variance was used to determine the effect of age, sex and their interaction within the normal group. When the age effect was statistically significant, a nonlinear regression was created. Areas under the receiver-operating characteristic curve (AUCs) were calculated to assess diagnostic accuracy. A total of 277 normal participants (mean [SD] age, 13.5 [2.6] years; 125 [45.1%] female) and 227 patients with RPD (mean [SD] age, 13.5 [2.6] years; 161 [58.1%] female) were analysed. It was found that in the normal group, in patients aged 7-10, TT-PCL distance (p = 0.006), TTL (p = 0.007) and TT-PCL/PTW (p < 0.001) were significantly larger in females than in males. A significant sex effect was also detected on TT-TG/TW (p = 0.014). TT-TG distance, TT-PCL distance, TTL and TT-PCL/PTW (in male patients) approached an established normal adult value of 12.3 mm, 20.9 mm, 0.64 and 0.28, respectively, with increasing age (p < 0.001). The AUC was greater for TT-TG/TDI and TT-TG/TW (p ≤ 0.01) and TT-TG/TDI outperformed TT-TG/TW in patients aged 15-18 (p = 0.004). Tubercle lateralisation increased with age and was affected by sex, with the exception of TT-TG distance and TT-TG/TDI. TT-TG/TDI is the optimal method of diagnosing a lateralized tibial tubercle in patients with RPD. These findings assist with the evaluation of tubercle lateralisation in that they provide a proper protocol for paediatric and adolescent populations with RPD; and thus, will help determine whether medial tubercle transfer should be included among the tailored surgical procedures considered for the treatment of patients with RPD. Level III.

The Dejour classification for trochlear dysplasia shows slight interobserver and substantial intraobserver reliability.

Trochlear dysplasia is one of the main risk factors for recurrent patellar dislocation. The Dejour classification identifies four categories that can be used to classify trochlear dysplasia. The purpose of this study is to evaluate the inter- and intraobserver reliability of the Dejour classification for trochlear dysplasia. The hypothesis was that both intra- and interobserver reliability would be at least moderate. This is a cross-sectional, reliability study. Twenty-eight examiners from the International Patellofemoral Study Group 2022 meeting evaluated lateral radiographs of the knee and axial magnetic resonance images from 15 cases of patellofemoral instability with trochlear dysplasia. They classified each case according to Dejour's classification for trochlear dysplasia (A-D). There were three rounds: one with only computed radiograph (CR), one with only magnetic resonance imaging (MRI) and one with both. Inter- and intraobserver reliability were calculated using κ coefficient (0-1). The mean age of patients was: 14.6 years; 60% were female and 53% had open physis. The interobserver reliability κ probabilities were 0.2 (CR), 0.13 (MRI) and 0.12 (CR and MRI). The intraobserver reliability κ probabilities were 0.45 (CR), 0.44 (MRI) and 0.65 (CR and MRI). The Dejour classification for trochlear dysplasia has slight interobserver reliability and substantial intraobserver reliability. Level I.

The tibial tubercle-to-trochlear groove distance changes in standing weight-bearing condition: An upright weight-bearing computed tomography analysis

BackgroundThe tibial tubercle-to-trochlear groove (TT-TG) distance and Insall-Salvati (I/S) ratio are widely used to determine the need for distal realignment in conjunction with medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent patellar dislocation. A TT-TG distance >20 mm and an I/S ratio >1.3 are significant anatomical risk factors for patellar instability. However, these parameters have traditionally been measured using non-weight-bearing (NWB) imaging modalities. As patellar dislocation occurs during weight-bearing actions, these two parameters should be measured under weight-bearing conditions. Thus, this study aimed to measure the TT-TG distance and I/S ratio using upright full-weight-bearing (FWB) computed tomography (CT) scans and compare the data with NWB CT scans. MethodsThis study included 49 knee joints of 26 healthy volunteers. CT images were obtained under both FWB and NWB standing conditions using a 320-detector row upright CT scanner. TT-TGs in the axial plane and I/S ratios in the sagittal plane were measured and compared. ResultsThe average FWB TT-TG distance was 20.3 ± 3.9 mm, whereas the average NWB TT-TG distance was 12.3 ± 4.7 mm. The TT-TG level was significantly higher in the FWB condition than that in the NWB condition (P < 0.001). The I/S ratios were comparable between the FWB and NWB conditions (P = 0.29). ConclusionsThe TT-TG distance in the standing weight-bearing condition was larger than the conventional TT-TG distance and surpassed the historical cutoff value of TT-TG, which may affect the indication of additional distal realignment in MPFL reconstruction for patellar instability.

Conversion of failed revision total knee arthroplasty in arthrodesis with modular nail maintaining the uncemented femoral stem in patient with extensor mechanism insufficiency: a case report

BackgroundThe transition from revision total knee arthroplasty (RTKA) to arthrodesis involves the replacement of cemented femoral and tibial stems with a modular nail designed for arthrodesis. This conversion process is associated with challenges such as bone loss, blood loss, and prolonged surgical durations. Effectively addressing these complexities through a less invasive surgical approach could be pivotal in enhancing patient outcomes and minimizing associated complications.Case presentationA 75-year-old white Caucasian female patient with a revision total knee arthroplasty (RTKA) performed with a modular uncemented rotating-hinge system, reporting an history of recurrent patellar dislocation, was referred to our institution after a fall resulting in periprosthetic tibial plateau fracture. The fracture was treated with open reduction and internal fixation, but afterwards the patient had been unable to walk again. Tibial stem was mobilized, and extensor mechanism was insufficient due to chronic incomplete quadriceps tendon rupture. The femoral stem was stable, so we decided to convert the rotating-hinge in a arthrodesis with an uncemented modular knee fusion nail maintaining the previous femoral stem.ConclusionsThe result was a successful arthrodesis with minimal bone and blood loss, reduced operative time, and optimal functional outcome at the one-year follow-up. This case highlights the advantage of using a modular knee revision platform system that gives the opportunity to convert a RTKA in arthrodesis.

Medial Patellofemoral Ligament and Lateral Patellofemoral Ligament Reconstruction after Tibial Tuberosity Transposition in a Young Woman with Patellar Instability

In patients with reccurent lateral and medial patellar instability, isolated medial patellofemoral ligament (MPFL) reconstruction may be insufficient due to poor lateral retinacular tissue quality. In this report, we describe a case of a patient that underwent simultaneous MPFL and lateral patellofemoral ligament (LPFL) reconstruction on the left knee due to chronic bidirectional patellar instability. A 29-year-old female patient presented with first-time lateral patellar dislocation five years ago due to acute strain. She underwent a tibial tuberosity transposition in another hospital. After the surgery, she suffered from recurrent medial and lateral patellar dislocation and presented to our center. MPFL and concomitant LPFL reconstruction on the left knee was simultaneously performed due to bilateral patellar dislocation. The patella was stable postoperatively, and the patient underwent physiotherapy with successful results to date. Single-time patellar dislocation should be treated conservatively. Surgical treatment after the first episode of dislocation can magnitude the risk of postoperative complications. The simultaneous reconstructing of the LPFL yields patellar fixation indistinguishable from the native LPFL. These grafts provide separate tensioning depending on body anatomy, allowing for individualized stability. Anatomical MPFL reconstruction is supported by well-established high-quality research. Reconstructing the LPFL anatomically yields patellar fixation indistinguishable from the native LPFL.

Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation.

The present study aimed to assess the clinical efficacy and imaging results of reconstruction of the medial patellofemoral ligament through a double bundle of single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation. Twenty-three patients with recurrent patellar dislocation, including ten males and 13 females, with 23 knee joints were enrolled according to the relevant criteria. Reconstruction of the medial patellofemoral ligament was performed through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity. Knee function was evaluated using visual analog scale (VAS) score, International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner score, and Kujala score at pre- and postoperative stages. Patellar stability was assessed by CT scans measuring tibial tuberosity-trochlear groove (TT-TG) distance, lateral patella displacement (LPD), congruence angle (CA), and patellar tilt angle (PTA). All 23 patients were effectively followed up for 13-28months (mean: 21.91 ± 4.14months). At the last follow-up, the postoperative VAS score, IKDC score, Lysholm score, Tegner score, and Kujala score of 23 patients were 1.13 ± 0.82, 87.35 ± 3.17, 90.22 ± 1.28, 4.35 ± 0.65, and 89.26 ± 1.96, respectively, as compared to the preoperative values of 5.91 ± 1.13, 30.96 ± 5.09, 30.30 ± 2.98, 1.26 ± 0.62, and 27.87 ± 3.46, respectively, and these differences were statistically significant (P < 0.001). At the last follow-up, the postoperative TT-TG, LPD, CA, and PTA values of the 23 patients were 8.80 ± 1.85mm, 6.01 ± 1.77mm, 11.32 ± 6.18°, and 9.35 ± 2.88°, respectively, compared to the preoperative values of 18.77 ± 1.74mm, 14.90 ± 4.07mm, 37.82 ± 5.71°, and 23.58 ± 3.24°, respectively, and the differences were statistically significant (P < 0.001). No relevant complications were observed in the 23 patients. Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation showed satisfactory medium-term efficacy, and further investigations are required to confirm the long-term efficacy of this approach.

Epidemiology of Lateral Patellar Dislocation Including Bone Bruise Incidence: Five Years of Data from a Trauma Center.

Systematic summary of the epidemiology of patellar dislocation is rare. This study aims to investigate sex-, age-, type-, injury causing events-, incidence of bone bruise and time from last injury (TFLI)-specific characteristics, and detail the epidemiological characteristics of patellar dislocation. In this descriptive epidemiological study, a total of 743 patients who have a history of lateral patellar dislocation with either first-time patellar dislocation (FPD) or recurrent patellar dislocation (RPD) between August 2017 and June 2022 at our institution met the inclusion criteria and were selected in this study. Patient characteristics including the type, gender, age, events leading to patellar dislocation, incidence of patellar bone bruise, and the time from last injury (TFLI) of patellar dislocation were retrospectively obtained and described. Magnetic resonance imaging scans (MRI) of the knee were reviewed for insuring bone bruise. Among the 743 patients with patellar dislocation who required surgical reconstruction of the medial retinaculum, 418 (56.2%) had RPD and 325 (43.8%) had FPD. There were more females (65.0%) than males (35.0%) in patellar dislocation patients. Among the female patients, those aged <18 years had higher incidence (31.4%) of patellar dislocation. Among the male patients, those aged <18 and 19-28 years had higher incidence (16.8%) of patellar dislocation. Of all age groups, the prevalence rate of patellar dislocationwas high in juvenile population and females, but with no statistical significance. The most common patellar dislocation-causing event was sport accidents (40.1%), followed by life accidents (23.2%). The incidence of left-knee patellar dislocation was slightly higher than that of right-knee patellar dislocation. The incidence of patellar bone bruise of RPD (63.2%) was significantly lower (p < 0.05) than that of FPD (82.2%). Patellar dislocation patients with bone bruise had shorter time from last injury (TFLI) than those without patellar bone bruise (p < 0.05). The incidence of bone bruise of RPD was lower than that of FPD, and patients with patellar bone bruise may have a shorter time from last injury than those without bone bruise.

Derotational distal femoral osteotomy improves subjective function and patellar tracking after medial patellofemoral ligament reconstruction in recurrent patellar dislocation patients with increased femoral anteversion: A systematic review and meta-analysis.

The purpose of this study is to systematically review and quantitatively analyse the clinical outcomes of combined derotational distal femoral osteotomy (D-DFO) and medial patellofemoral ligament reconstruction (MPFL-R) in the treatment of recurrent patellar dislocation (RPD) with increased femoral anteversion angle (FAA). This study was performed in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (Assessing the Methodological Quality Of Systematic Reviews) Guidelines. PubMed, Embase, Web of Science and Cochrane Library databases were searched to identify studies reporting clinical outcomes of combined D-DFO and MPFL-R in RPD patients with increased FAA. Data on patient-reported outcome measures, radiological parameters, patellar tracking as revealed by J-sign and complications were extracted based on the inclusion criteria. The Methodological Index for Non-Randomized Study score was used for quality assessment. Review Manager and R statistical software were used to perform the statistical analysis. Eleven studies with a total of 569 knees in 553 patients were included. Patients were predominantly female (79%). The weighted mean of FAA decreased from 33.6° to 13.0° (weighted mean difference = 20.59; p < 0.00001) after the combined procedure. Significant improvements (p < 0.00001) were identified in the Lysholm score (weighted mean: 55.5 vs. 80.4), International Knee Documentation Committee (IKDC) score (weighted mean: 52.8 vs. 78.6) and Kujala score (weighted mean: 54.5 vs. 80.6). The incidence of residual J-sign ranged from 14.3% to 38.3% with an overall pooled rate of 28.2% (95% confidence interval = 22.8%-33.6%). The overall redislocation rate was 1.1%. No patients experienced surgical site infection or bone nonunion. Two studies compared the clinical outcomes of MPFL-R with and without D-DFO. Compared with isolated MPFL-R, the combined procedure yielded a better Lysholm score (weighted mean: 84.9 vs. 79.3, p < 0.0001), IKDC score (weighted mean: 84.1 vs. 79.9, p = 0.001), Kujala score (weighted mean: 84.3 vs. 79.4, p < 0.0001) and a lower residual J-sign rate (26/97 [26.8%] vs. 44/105 [41.9%], p = 0.02), respectively. The combination of D-DFO and MPFL-R led to improved clinical outcomes and a low redislocation rate in patients with RPD and increased FAA. Additional D-DFO can achieve more favourable results in subjective function and patellar tracking than isolated MPFL-R in the setting of excessive FAA. Level IV.

Morphological Changes of the Posterior Femoral Condyle After Medial Patellar Retinaculum Plasty in Skeletally Immature Patients With Recurrent Patellar Dislocation and Trochlear Dysplasia.

Surgical correction for recurrent patellar dislocation (RPD) can improve femoral trochlear morphology; nonetheless, the effects of surgical correction on femoral condyle morphology are unclear. To investigate the morphological changes in the posterior femoral condyle in skeletally immature patients with RPD and trochlear dysplasia (TD) after surgical correction. Cohort study; Level of evidence, 3. A total of 20 skeletally immature patients with bilateral RPD and TD were included in this study. For each patient, the knee that was dislocated more frequently or had sustained a recent injury was treated with medial patellar retinaculum plasty (group S; n = 20 knees), and the asymptomatic or only occasionally dislocated contralateral knee was treated conservatively (group C; n = 20 knees). The lengths of the anterior medial and lateral femoral condyles and the lengths of the posterior medial and lateral femoral condyles were evaluated preoperatively and at the final follow-up. Trochlear morphological characteristics, tibial tuberosity-trochlear groove distance, and patellar tilt angle were compared between preoperative and final follow-up values with the 2-sample paired Student t test and were compared between groups S and C with the independent-samples t test. The mean follow-up time was 60.7 ± 4.8 months. No knee in group S experienced a redislocation, whereas 80% (16/20) of knees in group C experienced a dislocation. There were significant group differences in the ratio of the posterior medial femoral condyle (PMFC) to the posterior lateral femoral condyle (PLFC) (group S, 1.08 ± 0.05; group C, 1.14 ± 0.06; P = .042). There was no significant difference in the ratio of the anterior lateral femoral condyle to the anterior medial femoral condyle (group S, 1.16 ± 0.13; group C, 1.18 ± 0.09; P = .635). In group S, all trochlear morphological characteristics and patellofemoral joint characteristics improved compared with preoperatively (P≤ .047 for all). In addition, all values significantly differed between groups S and C at the final follow-up (P≤ .044 for all). The study findings demonstrated that the morphology of the posterior femoral condyle in skeletally immature patients with bilateral RPD and TD changes after surgical correction, with the PLFC growing faster than the PMFC.

Comparison of Failure Rates at Long-term Follow-up Between MPFL Repair and Reconstruction for Recurrent Lateral Patellar Instability.

The medial patellofemoral ligament (MPFL) is the primary soft tissue restraint to lateral patellar translation and is often disrupted by lateral patellar dislocation. Surgical management for recurrent patellar instability focuses on restoring the MPFL function with repair or reconstruction techniques. Recent studies have favored reconstruction over repair; however, long-term comparative studies are limited. To compare long-term clinical outcomes, complications, and recurrence rates of isolated MPFL reconstruction and MPFL repair for recurrent lateral patellar instability. Cohort study; Level of evidence, 3. A total of 55 patients (n = 58 knees) with recurrent lateral patellar instability were treated between 2005 and 2012 with either MPFL repair or MPFL reconstruction. The exclusion criteria were previous or concomitant tibial tubercle osteotomy or trochleoplasty and follow-up of <8 years. Pre- and postoperative descriptive, surgical, imaging, and clinical data were recorded for each patient. MPFL repair was performed on 26 patients (n = 29 knees; 14 women, 15 men), with a mean age of 18.4 years. MPFL reconstruction was performed on 29 patients (n = 29 knees; 18 women, 11 men), with a mean age of 18.2 years. At a mean follow-up of 12 years (range, 8.3-18.9 years), the reconstruction group had a significantly lower rate of recurrent dislocation compared with the repair group (14% vs 41%; P = .019). There were no differences in the number of preoperative dislocations or tibial tubercle-trochlear groove distance. The reconstruction group had significantly more time from initial injury to surgery compared with the repair group (median, 1460 days vs 627 days; P = .007). There were no differences in postoperative Tegner, Lysholm, or Kujala scores at the final follow-up. In addition, no statistically significant differences were detected in return to sport (RTS) rates (repair [81%] vs reconstruction [75%]; P = .610) or reoperation rates for recurrent instability (repair [21%] vs reconstruction [7%]; P = .13). MPFL repair resulted in a nearly 3-fold higher rate of recurrent patellar dislocation (41% vs 14%) at the long-term follow-up compared with MPFL reconstruction. Given this disparate rate, the authors recommend MPFL reconstruction over repair because of the lower failure rate and similar, if not superior, clinical outcomes and RTS.

Arthroscopically Assisted Double-Bundle Medial Patellofemoral Ligament Augmentation With Physeal-Sparing Suture Fixation for Recurrent Patellar Dislocation in Skeletally Immature Patients

Recurrent patellar dislocation is a common patellofemoral disease that affects active adolescents. The optimal surgical treatment of recurrent patellar dislocation in skeletally immature patients remains controversial. This Technical Note describes an arthroscopically assisted double-bundle medial patellofemoral ligament (MPFL) augmentation. Orthocord suture, with ideal strength and partial bioabsorbable characteristics, is used as the stabilizer to augment and protect the native MPFL during its biological healing. Under an arthroscope, patellar tunnels are created with Kirshner wire at the upper third point of the medial articular margin and the midpoint of the proximal articular margin. A physeal-sparing transosseous suture fixation technique is applied at the femoral attachment. Two femoral tunnels are made with half-circle cutting needle, which is pierced into the femoral origin of the MPFL and exits the posterior femoral cortex. After dynamic assessments of knee range of motion and patellofemoral congruence, free ends of the Orthocord suture bundle are tied together at the external opening of the femoral tunnel. Transosseous suture fixation balances the requirements of anatomic restoration, reliable fixation, and physeal preservation, and thus may provide a promising alternative to current algorithm of addressing recurrent patellar dislocation in pediatric population.

Clinical significance of polymorphisms of genes encoding collagen (COL1A1, COL5A1) and their correlation with joint laxity and recurrent patellar dislocation in adolescents

The aim of this study was to assess the coexistence of polymorphisms of the COL1A1 and COL5A1 genes with clinically diagnosed laxity and the occurrence of recurrent patellar dislocation in adolescents. The research group comprised 50 cases of recurrent patellar dislocation. The mean age at diagnosis was 14.2 years (10–17, SD 2.6). The control group consisted of 199 participants without a diagnosis of recurrent patellar dislocation, with a mean age of 15.2 (10–17 years, SD 2.7). Joint laxity by the Beighton scale was assessed. Analysis of the allele distribution of the analysed genes COL1A1 and COL5A1 revealed no statistically significant difference between the study group and the control group (p = 0.859 and p = 0.205, respectively). Analysis of the Beighton score showed a statistically significantly higher result in the study group than in the control group (p < 0.001). No correlation between the presence of polymorphisms and joint laxity diagnosis was confirmed. In conclusion, COL1A1 and COL5A1 gene polymorphisms are not significantly more common in adolescents with recurrent patellar dislocation than in healthy peers; there is also no correlation between joint laxity and polymorphisms of the COL1A1 and COL5A1 genes.Registered on ClinicalTrials.gov with ID: PMMHRI-2021.2/1/7-GW.