Patellar reconstruction in primary total knee arthroplasty using bone chips from routine cuts: A case report and review of literature.

BACKGROUND: Total patellectomy is currently reserved for exceptional cases, such as recalcitrant patellofemoral instability and comminuted fractures, due to its demonstrated negative impact on knee biomechanics. Therefore, managing patellectomy is crucial to mitigate its inherent deleterious effects. Various techniques have been described, including autologous or allogeneic bone grafts for reconstruction and soft tissue realignment to enhance the extensor mechanism. CASE SUMMARY: A 73-year-old male underwent a patellectomy due to a comminuted fracture, subsequently developing osteoarthritis and experiencing a decline in functional status. Concurrent with total knee replacement, we conducted a patellar reconstruction, incorporating routine bone cuts and utilizing bone chips to fashion a new patella. This intervention resulted in the restoration of full extension and improvement of knee function. CONCLUSION: Patellar reconstruction demonstrates benefits on knee mechanics and stabilization, contributing to enhanced outcomes and satisfaction following knee replacement. We present an affordable technique for managing patellectomized patients undergoing total knee replacement.

Patellar Resurfacing Is Not a Risk Factor for Postoperative Patella Baja in Total Knee Arthroplasty.

Background: Patella baja is a known complication of total knee arthroplasty (TKA). There is a limited understanding of the association between patellar resurfacing and the incidence of patella baja. We aimed to compare rates of patella baja between unresurfaced and resurfaced patellas in patients undergoing TKA. Methods: A retrospective review of patients who underwent TKA between October 2009 and January 2020 was performed. Patients were included if they had at least one preoperative radiograph and a 1-year follow-up radiograph. Blackburne-Peel index (BPI) and Insall-Salvati ratios (ISRs) were measured on preoperative and 1-year postoperative radiographs and were used to define patella baja vs pseudopatella baja. Statistical analysis was performed using a linear model analysis of variance and the Fisher's exact test. Results: Three hundred eighteen TKAs were included, with 176 being resurfaced and 142 unresurfaced patellas. Of the resurfaced group, 4% (7/176) had true patella baja, compared to 5.6% (8/142) of the unresurfaced patellas. Of the resurfaced patellas, 8% (14/176) had pseudopatella baja, compared to 7% (10/142) in the unresurfaced group. Patellar resurfacing was not associated with a higher incidence of patella baja (P = .60) or pseudopatella baja (P = .83). Lower preoperative ISRs (P = .04) and BPIs (0.03) were highly predictive of a higher incidence of patella baja post-TKA. Conclusions: Patellar resurfacing in TKA is not associated with a higher incidence of patella baja in TKA when compared to unresurfaced patellas. Lower preoperative ISRs and BPIs are highly predictive of a higher incidence of postoperative patella baja.

Functions and Effectiveness of Unloader, Patellofemoral, and Knee Sleeve Orthoses: A Review.

Background: Knee orthoses have been extensively used as a nonsurgical approach to improving knee deficiencies. Currently, arthritic knee conditions remain the leading cause of disability, and this number is expected to increase. As the use of knee orthoses varies widely, so has their effectiveness which is still largely debatable. Here, we present the functions and effectiveness of the three most prominent knee orthotic models dedicated to supporting knee osteoarthritis-unloader, patellofemoral, and knee sleeves. Purpose/Research Question: Considering the depth and diversity of the many clinical studies and documented laboratory reports published to date, this literature review was created to educate the clinician, patient, and researcher on common knee orthoses used for the management of arthritic knee conditions. In doing so, we discuss their design, biomechanical effects, and clinical efficacy, as well as broader outcomes, limitations, and recommendations for use. Results/Synthesis: The knee orthoses discussed within the scope of this paper are dedicated to protecting the knee against strenuous compressive loads that may affect the patellofemoral and tibiofemoral joints of the knee. Since the knee has multiple axes of motion and articulating surfaces that experience different loads during functional activities, it can be implied that, to a large extent, knee brace designs can differ drastically. Unloader knee orthoses are designed to decrease tibiofemoral and patellofemoral joint pressures. Patellofemoral knee orthoses are designed to decrease strain on the patellofemoral and quadriceps tendons while stabilizing the patella. Knee sleeves are designed to stabilize movements, reduce pain in joints, and improve proprioception across the knee joint. Conclusion: Although patients often report benefits from wearing braces, these benefits have not been confirmed by clinicians and scientific investigators. Results from these three orthosis types show that clinical efficacy is still elusive due to the different methodologies used by researchers. Layman Summary: Knee orthoses also referred to as knee brace are commonly used for support and stability of the knee. Unloader knee braces are designed to relieve and support those suffering from knee osteoarthritis by improving physical impairment and reducing pain. Patellofemoral knee braces aim to help patients manage patellofemoral pain syndrome. Rehabilitative compression sleeves, also known as knee sleeves, are often used to assist patients suffering from knee pain and laxity. Important findings on the three knee braces discussed show discrepancies in results. Their effectiveness and validity are yet to be understood.

No increased complication rate with the use of soft tissue quadriceps tendon autograft for primary ACL reconstruction - a systematic review.

BACKGROUND: The autograft of choice for anterior cruciate ligament reconstruction (ACLR) remains debateable. Recently there has been increased popularity of soft tissue quadriceps tendon (s-QT) autograft due to less donor site morbidity, reduced anterior knee pain and comparable re-operation and complication rates. The aim of this review was to analyse functional outcomes of primary ACLR using s-QT in adult population without the bone plug and to report its complication profile against other autografts. PATIENT AND METHODS: This systematic review was performed in accordance with PRISMA guidelines and a review of literature was conducted on four online databases (Medline, EMBASE, Cochrane and Google Scholar). Clinical studies reporting on patients undergoing primary ACLR with s-QT autograft or in comparison to BPTB or HS autografts with a minimum of 6 months follow-up were included. The studies were inclusive of only all soft tissue QT autograft regardless of the implants or fixation method used. Critical appraisal of studies was conducted using the Methodological Index for Non-Randomized Studies (MINORS) tool. RESULTS: Fourteen studies were eligible. There were three randomised control studies (RCT) and 11 non-randomised comparative studies with 1543 patients who underwent ACLR. 682 underwent s-QT, 498 had hamstring tendon (HT) and 174 had bone-patellar tendon-bone (BPTB). 60% (n = 930) were males and mean follow up was 23.6 months (6-65). Eight studies reported post-operative patient reported outcome measures (PROMs). The mean International Knee Documentation Committee (IKDC) score was 91.5 ± 15.1 whereas mean Lysholm score was 90 ± 3.9. Five studies reported on laxity with mean anterior tibial translation (ATT) of 1.28 ± 1.09 mm. Overall complication rate of s-QT ACLR was 6% with 3% graft failure, 0.52% arthrofibrosis, 0.2% infection, 0.75% revision ACLR. There was no significant difference in functional outcome scores, knee stability and range of motion (ROM) between s-QT, HT and BPTB. CONCLUSION: s-QT for ACLR has a comparable functional outcome, laxity, failure and with overall graft failure rate of 3%. LEVEL OF EVIDENCE: III; Systematic review and meta-analysis.

Prevalence of trochlear dysplasia in an 1162 retrospective cohort study using CT scans.

HYPOTHESIS/PURPOSE: The prevalence of trochlear dysplasia is common in different populations. BACKGROUND: The prevalence of trochlear dysplasia in the general population, categorised by sex, race, age, and body mass index, has been sparse. This study aimed to define the prevalence of trochlear dysplasia based on the latter categories. STUDY DESIGN: Cohort retrospective study. METHODS: 1162 skeletal mature healthy femora were obtained from a CT-scan-based modelling system (SOMA). Thin slice CT scans were acquired exclusively for medical indications such as polytrauma (20%), CT angiography (70%) and other reasons (i.e. Total Joint Replacement) (10%). Trochlear dysplasia was measured using Pfirmann's method. Patient demographics such as age, race and sex were recorded. RESULTS: The overall prevalence of trochlear dysplasia is 4.5% and is far more common in Asian female patients compared to Caucasian, African and Middle Eastern knees. CONCLUSION: Overall, the prevalence of dysplasia in the general population was determined to be 4.5%, with female patients being more likely to suffer from the condition. Patients of Asian and Caucasian race were more likely to have trochlear dysplasia, while Middle Eastern male patients displayed more dysplastic values than their female counterparts.

[A new fluoroscopic view to evaluate the medial and lateral articular reduction quality in patella fractures during internal fixation].

Objective: To introduce a new fluoroscopic method for assessing the quality of medial and lateral joint surface reduction during internal fixation of patellar fractures and to summarize the clinical outcomes of patients treated using this method. Methods: A retrospective analysis was conducted on the clinical data of 52 patients with patellar fractures treated between January 2018 and January 2022 who met the inclusion criteria. There were 27 male and 25 female patients, aged 21-75 years, with an average age of 62 years. The types of patellar fractures included 9 transverse fractures, 37 comminuted fractures, and 6 longitudinal fractures. According to the AO/Orthopaedic Trauma Association (AO-OTA)-2018 fracture classification, there were 21 cases of type 34A, 6 cases of type 34B, and 25 cases of type 34C. The time from injury to operation ranged from 1 to 5 days, with an average of 2.3 days. Treatments included internal fixation with hollow screws or hollow screw tension bands, with or without anchor repair. During operation, the medial and lateral joint surfaces of the patella were observed using the tangential fluoroscopic method to assess the smoothness of reduction of the median ridge, lateral joint surface, medial joint surface, and lateral joint edge. Patients were followed up regularly, and X-ray films were taken to observe fracture healing. Knee joint range of motion, Böstman score, and Lysholm score were used to evaluate functional recovery. Results: The tangential fluoroscopic method for the medial and lateral joint surfaces of the patella during operation showed satisfactory reduction of the joint surfaces and good positioning of the implants. All patients were followed up 12-16 months, with an average of 13.4 months. During the follow-up, fracture displacement occurred in 1 case and titanium cable breakage in 1 case. All patella fractures healed successfully, with a healing time of 8-16 weeks (mean, 11.4 weeks). At last follow-up, knee joint range of motion ranged from 120° to 140°, with an average of 136°. The Böstman score ranged from 20 to 30, with an average of 28, yielding excellent results in 45 cases and good results in 7 cases. The Lysholm score ranged from 88 to 100, with an average of 93, yielding excellent results in 40 cases and good results in 12 cases. Conclusion: The intraoperative application of the tangential fluoroscopic method for the medial and lateral joint surfaces of the patella can quickly determine the fluoroscopic plane of the patella, accurately assess the quality of fracture reduction and the position of internal fixator, thereby improving effectiveness.

Knee Extensor Apparatus Reconstruction with Allograft after Patellar Resection: A Case Report.

Background: The extensor apparatus of the knee can be thought of a chain that transmits the muscular strength developed by the quadriceps muscles to the proximal tibia. This complex is essential to allow the extension of the tibia over the femur, being essential to provide knee mobility and stability. In case of lesions which irreparably damage the patella, such as a locally aggressive bone tumor, it is necessary to restore both the apparatus' anatomical continuity and its strength. Case report: A 39-years-old Caucasian man with a history of lung carcinoma developed atraumatic swelling and soreness in his left knee. Imaging evidence reported a degeneration of the left patella. We performed an en bloc resection of the patella and the nearby soft tissues of the extensor apparatus. The resulting gap was fulfilled with a massive allograft consisting of a quadriceps tendon, a patella and a patellar ligament. No complication or local recurrences were observed. At the patient's latest follow-up, he did not have any extension lag and quadriceps strength was completely restored. Conclusion: Massive allografts can represent a reliable alternative for the reconstruction of the patella and the knee extensor apparatus in orthopedic oncology.

Complications following surgical treatment of patella fractures - a systematic review and proportional meta-analysis.

PURPOSE: The aim of this systematic review and proportional meta-analysis was to identify complications of surgical treatment of patella fractures and to estimate their incidence. We extended existing knowledge on this topic by including several more recent and large-scale studies. METHODS: This systematic review and meta-analysis were performed in accordance with the Cochrane Handbook for systematic reviews of interventions. After searching in PubMed, MEDLINE, EMBASE, Cochrane Library, and OpenGrey, all studies after 2000, with study populations > 100 patients, including only patients > 18 years and follow-up > 30 days, were included. Two independent authors assessed the literature search and extracted the data. The risk of bias was assessed using the Newcastle-Ottawa Quality Assessment Scale. The meta-analysis was performed on complications pooled in infections, nonunion, symptomatic implant removal, and fixation failure. RESULTS: The data on complications were available from 14 studies, including a pool of 5659 patients. The most common complication was symptomatic implant removal, affecting. CONCLUSION: Surgically, treatment of patella fractures was associated with a high risk of complications. The most common complication was symptomatic implant removal, affecting 29.6% of patients. Other complications stated were fixation failure 5.2%, infections 3.1% and nonunion 1.7%.

Anterior variable angle locking neutralisation plate superiority over traditional tension band wiring for treating transverse patella fractures.

Purpose: This paper investigates the biomechanical benefits of using hybrid constructs that combine cannulated screws with tension band wiring (TBW) cerclage compared to cannulated screws with anterior Variable Angle locking neutralisation plates (VA LNP). These enhancements can bear heavier loads and maintain the repaired patella's integrity, in contrast to traditional methods. Method: Eighteen fresh-frozen human cadaver patellae were carefully fractured transversely at their midpoints using a saw. They were then divided into two groups of nine for subsequent utilisation. Fixation methods included Cannulated Screw Fixation added with either TBW or VA LNP Fixation Technique. Cyclic loading simulations (500 cycles) were conducted to mimic knee motion, tracking fracture displacement with Optotrak. After that, the constructs were secured over a servo-hydraulic testing machine to determine the load-to-failure on axial mode. Results: The average fracture displacement for the anterior neutralisation plate group was 0.09 ± 0.12 mm, compared to 0.77 ± 0.54 mm for the tension band wiring with cannulated screw group after 500 cyclic loading. This result is statistically significant (p = 0.004). The anterior neutralisation plate group exhibited a mean load-to-failure of 1359 ± 21.53 N, whereas the tension band wiring group showed 780.1 ± 22.62 N, resulting in a significant difference between the groups (p = 0.007). Conclusion: This research highlights the superior biomechanical advantage of VA LNP over TBW for treating simple transverse patella fractures with two cannulated screws. It also highlights how the TBW is still a valuable option considering the load-to-failure limit. Level of Evidence: Not Applicable.

Patellar articular overlap is better associated with patellar alignment during weight-bearing than traditional measures of patellar height.

BACKGROUND: A consequence of a high riding patella is reduced osseous stability and malalignment of the patella (i.e., lateral patellar tilt and displacement). Although quantification of patellar height is a routine part of the radiographic examination of the patellofemoral joint, it is not clear which measure of patellar height is best associated with patella alignment. HYPOTHESIS/PURPOSE: To determine if patellar articular overlap (PAO) is better associated with lateral patellar tilt and lateral patellar displacement compared to traditional measures of patellar height. STUDY DESIGN: Cross-sectional. METHODS: Magnetic resonance images were obtained from 50 female participants (21 with patellofemoral pain and 29 healthy controls) under loaded conditions (25-35% bodyweight) at 15-20 degrees of knee flexion. Measurements of lateral patellar tilt and displacement as well as the PAO, Insall-Salvati ratio (ISV), Caton Deschamps-index (CD-index), or the Blacburn Peel-index (BP-index) were obtained from sagittal and axial plane images. RESULTS: The PAO was found to significantly correlated with lateral patellar tilt (r = -0.77, p < 0.001). In contrast, the ISV, CD-index, or the BP-index were not found to be associated with lateral patellar tilt (r = 0.13, p = 0.34; r = -0.14, p = 0.33; r = -0.08, p = 0.56, respectively). Both the PAO and ISV were found to be significantly correlated with lateral patellar displacement (r = -0.52, p < 0.001; r = 0.43, p = 0.002, respectively). Conversely, the CD-index and BP-index were not found to be associated with lateral patellar displacement (r = 0.03 p = 0.83; r = 0.05 p = 0.74, respectively). CONCLUSION: Of the measures of patellar height evaluated, the PAO was found to provide the greatest association with lateral patellar tilt and displacement.

Risk Factors for Atraumatic Medial Patellar Facet Lesions.

Background: Medial patellar facet lesions have been well-described in the setting of patellar instability. However, relatively little is known about risk factors for atraumatic medial patellar facet lesions. Purpose/Hypothesis: To identify clinical and radiographic risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability. It was hypothesized that a posterior tibial tubercle relative to the trochlear groove would be a risk factor for atraumatic medial patellar facet lesions. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 37 patients with atraumatic medial patellar facet lesions were matched by age, sex, and body mass index with 37 control patients without a history of patellofemoral dysplasia. Demographic and imaging characteristics were compared between groups. Plain radiography was used to evaluate Wiberg type, and magnetic resonance imaging was used to calculate Caton-Deschamps index, tibial tubercle-trochlear groove distance, trochlear facet asymmetry ratio, patellotrochlear index, sulcus depth, patellar bisect ratio, and tibial tubercle height. Statistically significant variables from univariate analysis were used as inputs to the multivariate regression model to assess independent risk factors. Results: There were no differences between groups with respect to Wiberg type, Caton-Deschamps index, tibial tubercle-trochlear groove distance, sulcus depth, or patellotrochlear index (P > .05 for all). The medial facet lesion group had a larger medial trochlear facet (trochlear facet asymmetry ratio, 0.72 ± 0.11 vs 0.60 ± 0.09; P < .001), a more medial-lying patella in the trochlear groove (patellar bisect ratio, 0.57 ± 0.06 vs 0.55 ± 0.07; P = .035), and a more posterior tibial tubercle relative to the trochlear groove (tibial tubercle height, -3.13 ± 5.21 vs -0.23 ± 5.93 mm; P = .030) compared with the control group. Multivariate regression analysis identified trochlear facet asymmetry and tibial tubercle height as independent risk factors for medial patellar facet lesions (relative risk = 97.3 [95% CI, 14.9-635.1], P < .001 and relative risk = 0.95 [95% CI, 0.92-0.98], P = .004, respectively). Conclusion: A relatively larger medial trochlear facet and a more posterior tibial tubercle relative to the trochlear groove were found to be risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability.

An evaluation of a novel method for the MRI-based assessment of Caton-Deschamps index in the Knee.

INTRODUCTION: The radiographical assessment of patella height has historically been performed using X-Ray. The aim of this study was to evaluate a new method for the assessment of patella height using MRI and to assess the correlation with the X-Ray based assessment. MATERIALS AND METHODS: 159 patients who had both lateral radiographs and MRI images were included. Parameters measured included traditional radiographical CDI, MRI-based CDI, and TT-TG distance. On the basis of the TT-TG, the patients were divided into 2 groups. Two different methods were used to assess CDI using MRI: using a single slice image, and an alternative technique using two different cross-sectional images. The correlation of the two measurement methods was assessed using Pearson's correlation coefficient. The intraclass correlation coefficient (ICC) was determined from the measurements of the two investigators. RESULTS: The average TT-TG distance was 11.6 mm (± 4.6). In patients with a TT-TG < 15 mm, both measurement methods showed comparable correlation with measurements on X-Ray. In patients with a TT-TG of > 15 the the new cross-sectional imaging method showed higher correlation with traditional X-Ray assessment compared to CDI assessment using the traditional single slice method (r = 0.594, p < 0.001 vs. r = 0.302, p = 0.055). CONCLUSIONS: The assessment of CDI on MRI using a cross-sectional imaging method has a better correlation with traditional X-Ray assessment of CDI than single-slice assessment. This is particularly true in patients with elevated TT-TG and as such should be preferentially used in the assessment of Patellar height in this cohort.

Midterm Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome.

Background: Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown. Purpose: To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes. Study Design: Case series; Level of evidence, 4. Methods: In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed. Results: The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts (P = .69). For autografts, 6 of 17 (35.3%) failures occurred with gracilis, but 0 of 13 (0%) occurred with semitendinosus (P = .02). Compared with patients without failures, patients with failed primary MPFLR were significantly younger (P = .0005) and were able to touch the palm to the floor with their knees extended (P = .03). For radiographic parameters, the patellar height and tilt were significantly higher in the failure group. The postoperative PROs were suboptimal at a mean follow-up of 5.2 years. All but 1 patient were satisfied with the final outcome. Conclusion: At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.

Supratubercle Anterior Closing Wedge Osteotomy: No Changes in Patellar Height and Significant Decreases in Anterior Tibial Translation at 6 Months Postoperatively.

BACKGROUND: Because of the increased prevalence of revision anterior cruciate ligament (ACL) reconstruction, there has been a desire to understand the role of posterior tibial slope on increased anterior tibial translation and increased ACL graft forces. One potential concern in supratubercle anterior closing wedge proximal tibial osteotomy (ACW-PTO) for decreasing the posterior tibial slope is the risk of altering the patellar height. PURPOSE: To radiographically assess changes in (1) patellar height, (2) anterior tibial translation, and (3) posterior tibial slope after supratubercle ACW-PTO. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who underwent supratubercle ACW-PTO by a single surgeon between July 2019 and June 2023 were included. Standardized lateral knee weightbearing radiographs to assess patellar height (via the Caton-Deschamps index), anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle, and posterior tibial slope were obtained at 4 time points (preoperatively and 1 day, 3 months, and 6 months postoperatively). Paired t test was used to compare differences between preoperative, 1-day, and 3- and 6-month values for patellar height as measured using the Caton-Deschamps index and for posterior tibial slope. Paired t test was also used to compare differences in the preoperative and 6-month postoperative values for anterior tibial translation. RESULTS: In 20 patients after ACW-PTO, the Caton-Deschamps index demonstrated a significant increase in patellar height on postoperative day 1 (P < .001) but no significant differences at 3 (P = .057) and 6 (P = .176) months postoperatively. Anterior tibial translation on standing lateral knee radiographs was significantly decreased by a mean of 8.9 mm from preoperatively to 6 months postoperatively (P < .001). Posterior tibial slope was significantly decreased by a mean of 11.2° from preoperatively to 6 months postoperatively (P < .001). CONCLUSION: Supratubercle ACW-PTO performed for ACL reconstruction failure in the setting of an increased posterior tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, after ACW-PTO, there was a significant decrease in anterior tibial translation and posterior tibial slope.

Robotic Assessment of Patella Tracking in Total Knee Arthroplasty.

OBJECTIVES: Robotic-tools have been developed to improve planning, accuracy and outcomes in total knee arthroplasty (TKA). The purpose of this study was to describe and illustrate a novel technique for assessing the patellofemoral (PFJ) in TKA using an imageless robotic platform. METHODS: A consecutive series of 30 R-TKA were undertaken by a single-surgeon utilising the described technique. A technique to dynamically assess the PFJ intra-operatively, pre and post implantation was developed. A full set of data from 9 cases was then collected and reviewed for analysis. A series of dynamic PFJ tracks collected intra-operatively pre and post implantation are presented. Furthermore, a full assessment of PFJ over and under-stuffing through a 90° arc of flexion is illustrated. Finally, a pre and post centre of rotation for the PFJ was defined and measured. RESULTS: The described technique was defined over a series of 30 R-TKA using the described robotic platform. Nine cases were analysed to determine what data could be measured using the robotic platform. Intra-operative real-time data allowed a visual assessment of PFJ tracking through a range of motion of 0° to 90° flexion pre and post-implantation. PFJ over and under-stuffing was also assessed intra-operatively through a range of motion of 0° to 90° flexion. Post operative analysis allowed a more detailed study to be performed, including defining a pre and post implantation centre of rotation (COR) for the patella. Defining the COR allowed the definition of a patella plane. Furthermore, patella mediolateral shift in full extension, and end flexion could be measured. CONCLUSION: Intra-operative assessment of the PFJ in TKA is challenging. Robotic tools have been developed to improve measurement, accuracy of delivery and outcomes in TKA. These tools can be adapted in novel ways to assess the PFJ, which may lead to further refinements in TKA techniques.

Chitosan-based scaffold augmentation to microfractures: Stable results at mid-term follow-up in patients with patellar cartilage lesions.

Purpose: Patellar cartilage lesions are a frequent and challenging finding in orthopaedic clinical practice. This study aimed to evaluate a chitosan-based scaffold's mid-term clinical and imaging results patients with patellar cartilage lesions. Methods: Thirteen patients (nine men, four women, 31.3 ± 12.7 years old) were clinically evaluated prospectively at baseline, 12, 24 and at a final minimum follow-up of 60 months (80.2 ± 14.7) with International Knee Documentation Committee (IKDC) subjective, Knee Injury and Osteoarthritis Outcome Score and Tegner scores. A magnetic resonance analysis was performed at the last follow-up using the Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) 2.0 score. Results: An overall significant clinical improvement in the scores was observed from baseline to all follow-ups, with stable clinical results from 24 months to the mid-term evaluation. The IKDC subjective score passed from 46.3 ± 20.0 at baseline to 70.1 ± 21.5 at the last follow-up (p = 0.029). Symptoms' duration before surgery negatively correlated with the clinical improvement from baseline to the final follow-up (p = 0.013) and sex influenced the improvement of activity level from the preoperative evaluation to the final follow-up, with better results in men (p = 0.049). In line with the clinical findings, positive results were documented in terms of cartilage repair quality with a mean MOCART 2.0 score of 72.4 ± 12.5. Conclusions: Overall, the use of this chitosan-based scaffold provided satisfactory results with a stable clinical improvement up to mid-term follow-up, which should be confirmed by further high-level studies to be considered a suitable surgical option to treat patients affected by patellar cartilage lesions. Level of Evidence: Level IV, prospective case series.

Outcomes of treatment of patella fractures in children and adolescents.

Purpose: The purpose of this study is to assess clinical and functional outcomes in separate cohorts of operatively and nonoperatively managed pediatric patella fractures. Methods: A retrospective review was completed for patients aged 5-19 years treated for a unilateral patella fracture at a single pediatric level-1 trauma center. Patients were excluded for osteochondral fracture associated with patellar dislocation, polytrauma presentation with additional fractures, or <3 months of clinical follow-up. Functional outcomes were assessed via the Pediatric International Knee Documentation Committee form and the Marx Knee Activity Scale. Results: A total of 53 patients met inclusion criteria; 30 patients were treated operatively and 23 patients were treated nonoperatively. Patients with patellar sleeve/pole fractures were significantly younger by 5.2 years (p < 0.01) and presented with greater variability in mechanism of injury (p < 0.01). The nonoperative cohort achieved bony healing and returned to sports at a median (interquartile range) of 1.7 (1.2-2.3) months and 2.8 (2.3-3.3) months, respectively, post-injury. The operative group achieved bony healing and returned to sports at 2.8 (2.1-3.5) months and 5.9 (4.0-7.1) months, respectively, following surgery. Median (interquartile range) Pediatric International Knee Documentation Committee and Marx scores were 98 (89-100) and 14 (10-16), respectively, for the nonoperative group, and 92 (84-99) and 13 (12-16), respectively, for the operative group. No significant differences in patient-reported outcomes were observed between fracture patterns or treatment cohorts. Conclusion: Pediatric and adolescent patients sustaining patella fractures reported long-term functional outcomes comparable to normative values, across multiple fracture patterns and with appropriate operative and nonoperative treatment. Fractures requiring surgery were expectedly associated with slower healing and return to sport timelines. Level of evidence: Therapeutic Level III.

Evaluation of Patella Anatomy for Total Knee Arthroplasty Approaches.

BACKGROUND: The patella, or kneecap, is a sesamoid bone situated deep to the fascia latae and the tendinous fibers of the rectus femoris. The medial and lateral facets of the patella articulate with the medial and lateral condyles of the femur, respectively, to form the patellofemoral component of the knee joint. When joint cartilage is destroyed due to osteoarthritis, inflammatory arthritis, post-traumatic degenerative joint disease, or osteonecrosis/joint collapse with cartilage loss, a surgical treatment called knee arthroplasty, or total knee arthroplasty (TKA), is used to rebuild the knee joint. OBJECTIVES: The purpose of our study is to provide a detailed morphometric analysis of the human patella. METHODS: A total of 168 patellae (86 left, 82 right) were examined. Eleven parameters were determined to evaluate patella morphometry, and the bones were also evaluated with the Wiberg classification. RESULT: Type I patella was observed in 13 samples (7.74%); 109 (64.88%) and 46 (27.38%) were Type II and Type III, respectively. In the statistical analysis, significant differences were found between the right and left patellae in terms of patellar thickness, vertical ridge length, and Wiberg angle (p<0.05). There were also significant differences between the Wiberg types and the medial articular width and lateral articular width (p<0.05). CONCLUSION: In order to avoid potential difficulties during knee surgery, it is crucial to understand the typical morphological and morphometric properties of the patella. We believe that this study will be useful to surgeons who perform surgical approaches to the knee and to clinicians who evaluate the diseases of the region.

The role of the most cranial trochlear orientation in patellar maltracking to better characterise trochlear morphology.

PURPOSE: The purpose of our study is to describe a magnetic resonance imaging quantitative parameter to assess the morphology of the trochlea that could be measurable from normal to high-grade trochlear dysplasia while evaluating the most proximal slice with trochlear cartilage. METHODS: Two groups of patients have been compared: patients with no patellofemoral pain, no previous trauma and undergoing surgery for a suspected isolated meniscal tears (group A) and patients with objective patellar instability (group B). The cranial trochlear orientation (CTO) angle is defined as the angle between the posterior bicondylar line and the most lateral and most medial points on the subchondral bone covered by cartilage digitised on the first and most cranial image with the trochlear cartilage clearly visible. RESULTS: The final cohort included 253 patients (109 in group A and 144 in group B). CTO was significantly higher in group B (-2.5 ± 8.4 vs. -10.8 ± 5,1; p < .001). Moreover, 75% of knees in group B had a CTO > -7°, while 75% of knees in group A had a CTO < -7°. CTO was measurable in all 253 knees, whereas the lateral trochlear inclination and the sulcus angle were measurable in only 202 knees. The entire cohort was also divided into knees with CTO ≤ 0° and CTO > 0°. All knees with a CTO > 0 were in group B, and 49% of knees with CTO < 0 were in group B. CTO was positively correlated with lateral patellar tilt. CONCLUSIONS: CTO is the only parameter that can be measured on the most cranial slice, in every patient, even in high-grade trochlear dysplasia. According to this new system, the axial trochlear shape may be divided into two types: a positive CTO and a negative CTO, with the trochlea serving, respectively, as a medial and lateral barrier. LEVEL OF EVIDENCE: Level III.

ST-segment elevation myocardial infarction in Nail-Patella syndrome with anomalous coronary anatomy and aneurysms: a case report.

Background: Nail-Patella syndrome (NPS) is an autosomal-dominant pleiotropic condition characterized by pelvic and skeletal abnormalities and most commonly affecting a tetrad of nails, knees, elbows, and iliac horns, the iliac horns being pathognomonic for the condition. The most well-documented extra-skeletal manifestation is renal involvement with alteration in Type III collagen. No documented cases of NPS with anomalous coronary arteries or aneurysms, acute coronary occlusion, or successfully coronary interventions exist in the medical literature. Case summary: A 62-year-old female with a medical history significant for NPS diagnosed 50 years ago presented to the emergency department with a chief complaint of chest pain. She recently developed end-stage renal disease managed with peritoneal dialysis within the last year. Angiography revealed 100% right coronary artery occlusion with an anomalous take-off from the left circumflex artery. She demonstrated diffuse coronary aneurysms in the right coronary artery, mid-left anterior descending artery, and other epicardial vessels. Two drug-eluting stents were placed in overlapping fashion. Following careful apposition, the aneurysmal segment was successfully stented without complication. The patient was discharged without complication 2 days later. Discussion: Our case shows the first reported case of coronary vascular anomalies and successful coronary revascularization in a patient with NPS in the medical literature. Given the recently reported vascular anomalies and known collagen alterations seen in patients with the genetic disorder, clinicians should suspect further systemic vascular anomalies with their own unique therapeutic challenges when encountering patients with this rare genetic syndrome.