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

PURPOSE: To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD). METHODS: 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. RESULTS: 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). CONCLUSION: 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 OF EVIDENCE: Level III.

Patellar osteochondritis dissecans: maturation-dependent patellofemoral joint characteristics.

BACKGROUND: The likelihood of healing of osteochondritis dissecans decreases with skeletal maturity and there are theories that abnormal biomechanical forces contribute to the development and progression of these lesions. OBJECTIVE: To characterize, according to regional skeletal maturity, the morphology and alignment indices of the patellofemoral joint on MRI in patients with patellar osteochondritis dissecans. MATERIALS AND METHODS: MRI examinations of patients with patellar osteochondritis dissecans obtained between January 2008 and May 2023 were retrospectively reviewed to determine regional skeletal maturity, osteochondritis dissecans lesion size and location, patellar and trochlear morphology (Wiberg/Dejour classifications), and to calculate trochlear sulcus angles, trochlear depth index, lateral trochlear inclination, Insall-Salvati index, Caton-Deschamps index, patellar tendon-lateral trochlear ridge, and tibial tubercle-trochlear groove distances. Values were compared between skeletally immature and mature groups. RESULTS: Sixty-eight children (22 girls, 46 boys, age: 14.0 ± 1.7 years) yielded 74 knees with patellar osteochondritis dissecans lesions, 14 (19%) of which were skeletally mature. The most common anatomic location was over the central patella [median ridge (34/74 - 46%) on the axial images and over the middle third (45/74 - 61%) on the sagittal images]. Overall, mean trochlear sulcus angle (high, 151 ± 11°), trochlear depth index (low, 2.8 ± 1.4 mm), and Insall-Salvati index (borderline, 1.3 ± 0.1) were abnormal for the entire sample. Skeletally mature knees were significantly more likely to have higher (more dysplastic) Dejour types when compared to skeletally immature knees (p < 0.01). Knees in the mature group, compared to immature, had significantly more abnormal mean lateral trochlear inclination (15 ± 8° vs. 19 ± 6°, p = 0.03) and patellar tendon-lateral trochlear ridge distance (5.55 ± 4.31 mm vs. 2.89 ± 4.69 mm, p = 0.04). Half of the knees had ≥ 4 abnormal features that predispose to patellofemoral maltracking; mature knees were significantly (p = 0.02) more likely to have a higher number of abnormal features (> 6 features, 7/14, 50.0%) versus immature knees (0-3 features, 33/60, 55.0%). CONCLUSION: In children with patellar osteochondritis dissecans, abnormal patellofemoral morphology and alignment indices were common in all patients and more severe in mature knees.

[Radiological diagnostics of patellofemoral instability and patellar dislocation]. / Radiologische Diagnostik der patellofemoralen Instabilität und Patellaluxation.

Patellofemoral instability (PFI) describes a (sub)luxation of the patella in the patellofemoral joint. Pathophysiologically, PFI is usually due to a nonphysiological movement of the patella, so-called maltracking, either due to acute trauma with injury to the supporting ligamentous apparatus or due to the presence of anatomical risk factors. Radiologically assessable risk factors for maltracking include trochlear dysplasia, patella alta, patellar tilt, lateralization of the tibial tuberosity, torsional deformity and genu valgum. This article presents the most commonly used and best validated measurement techniques. In addition, the characteristic injury pattern after lateral patellar dislocation is shown.

Varus osteotomy as a salvage procedure for young patients with symptomatic patellofemoral arthritis and valgus malalignment at short- to mid-term follow-up: a case series.

PURPOSE: The purpose of the study was to report the clinical, functional and radiological outcome following varus osteotomy as a salvage procedure in young to middle-aged patients with patellofemoral arthritis (PFA) and associated valgus malalignment. It was hypothesized that a significant improvement in knee function and reduction in pain would be achieved. Moreover, no conversion to patellofemoral joint arthroplasty could be observed. MATERIAL AND METHODS: Patients (< 50 years of age) that underwent varus osteotomy between 08/2012 and 01/2020 for the treatment of symptomatic PFA and associated valgus malalignment were consecutively included (minimum follow-up: 24 months). Patient-reported outcome measures (PROM; International Knee Documentation Committee subjective knee form [IKDC]), Visual Analog Scale [VAS] for pain, Tegner Activity Scale [TAS], and satisfaction with the postoperative results (1-10-scale, 10 = highest satisfaction) and weight-bearing whole-leg anteroposterior radiographs were conducted pre- and postoperatively. The change in PROM and femorotibial angle (FTA) were tested for statistical significance. RESULTS: In total, 12 patients (14 knees) were included (66.7% female; mean age: 33.8 ± SD 6.6 years). In ten cases, lateral opening-wedge distal femoral osteotomies (DFO) were performed, of which three cases included a concomitant femoral derotation. Three medial closing-wedge DFO and one medial closing-wedge high tibial osteotomy were performed. At follow-up (55.3 ± 29.3 months), a significant improvement in knee function (IKDC: 56.4 ± 14.4 to 69.1 ± 11.2, p = 0.015) and reduction in pain (VAS for pain: 3.5 [interquartile range 2.3-5.8] to 0.5 [0-2.0], p = 0.018) were observed. Patients were able to reach their preoperative sporting activity level (TAS: 3.0 [3.0-4.0] to 3.5 [3.0-4.0], p = 0.854) and were highly satisfied with the postoperative result (9.0 [6.5-10]). Additionally, a significant correction of valgus malalignment was observed (5.0° ± 2.9° valgus to 0.7° ± 3.2° varus, p < 0.001). Regarding complications, two re-osteosyntheses were performed due to loss of correction and delayed union. No conversion to patellofemoral arthroplasty occurred. CONCLUSION: In patients with symptomatic PFA and associated valgus malalignment, varus osteotomy as a salvage procedure achieved a significant improvement in knee function and reduction in pain. No conversion to patellofemoral joint arthroplasty occurred at short- to mid-term follow-up. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

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.

PURPOSE: 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). METHODS: 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. RESULTS: 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. CONCLUSION: 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 OF EVIDENCE: Level IV.

Variations in Trochlear Morphology of Contemporary and Legacy Total Knee Arthroplasty Prostheses: A Review of 22 Designs.

BACKGROUND: The morphology of the trochlear compartment of total knee arthroplasty (TKA) prostheses is a major determinant of postoperative patello-femoral kinematics, particularly with unresurfaced patellae. The objective of this study was to quantify and compare the trochlear morphology of a large series of contemporary and legacy TKA designs. METHODS: The 3-dimensional surface models of 22 femoral components (13 contemporary and 9 legacy) were created using high-resolution laser scanning. The trochlear profile of each component was analyzed from proximal to distal in 15° increments around the trochlear axis. In each profile, the following variables were measured: sulcus angle, medio-lateral deviation of the sulcus, the height and width of the facets, and the trochlear groove orientation. RESULTS: In the contemporary group, the sulcus angle decreased progressively along the trochlear arc to varying degrees, except for 2 symmetrical designs, whereas the sulcus angle of the legacy designs showed considerable variability. The height of the medial facet was very strongly correlated with that of the lateral facet in the contemporary group (R2 = 0.89), whereas the correlation was weak for the legacy designs (R2 = 0.36). Moreover, the trochlear sulcus deviated laterally from distal to proximal in 10 contemporary designs and 7 legacy designs, resulting in a trochlear groove orientation of 4.2 to 11.1° and 4.3 to 10.5°, respectively. In the remaining 5 designs (3 contemporary and 2 legacy), the sulcus was vertical. CONCLUSIONS: There is more consistency in trochlear morphology of contemporary TKA designs compared to that of legacy designs, yet there are still large variations between different designs.

Influence of Lateral Retinacular Release in Realigning the Patella Between Varus and Valgus Knees in Primary Total Knee Arthroplasty.

Purpose: Our study aims to find the role of lateral retinacular release (LRR) on realigning the patella in knees with maltracking during primary total knee arthroplasty. We also compared the patellar morphological factors between the varus and valgus knees on predicting the need for LRR. Methods: We have retrospectively analyzed the incidence of LRR in consecutive 152 primary TKA (124 patients) from May 2018 to December 2018. We have evaluated the preoperative radiological parameters like Wiberg's patellar morphological type, patellar angle, sulcus angle, patellar width and thickness, preoperative patellar tilt and patellar shift, lateral patellofemoral angle and congruent angle. Post-operatively, patellar shift and patellar tilt were measured. Multivariate regression analysis was used to find the association of LRR with the individual radiological parameters. Results: There was no statistical difference in the postoperative patellar shift and tilt between lateral released and non-released groups, suggesting realignment of the patella after LRR (p > 0.05). The morphological parameters like patellar shift, lateral patellofemoral angle and congruent angle were significantly increased in valgus knees compared to varus knees (p < 0.05). The preoperative patellar shift of > 3.5 mm have a specificity of 93.7% and a negative predictive value (NPV) of 92.7%, congruent angle > 16° have a specificity of 85.3% and NPV of 4.2% in varus knees in predicting LRR. Conclusion: Radiological parameters of patellar maltracking like increased patellar tilt and lateral patellar shift get corrected postoperatively after performing the lateral release. Patella with Wiberg type 3 morphology, patellar shift > 3.5 mm and congruent angle > 16° in axial view tend to have an increased chance of lateral retinacular release.

Early Postoperative Complications and Associated Variables After Tibial Tubercle Osteotomy: A 15-Year Experience From a Single Academic Institution.

Background: Tibial tubercle osteotomy (TTO) is a well-established surgical treatment option for patients with patellofemoral disorders. Purpose: To determine the rate of early (≤90 day) postoperative complications after TTO and variables related to postoperative complications. Study Design: Case series; Level of evidence, 4. Methods: Patients who underwent TTO at a single academic institution within a 15-year period (2008-2022) were identified. All patients with a minimum 90-day follow-up were considered for study inclusion. Exclusion criteria were age younger than 14 years and revision surgery. Patient characteristics, surgical history, and concomitant procedures were identified, and risk factor analysis was performed to identify variables associated with early postoperative complications. Results: A total of 344 knees in 313 patients met eligibility criteria and were included in the final analysis. One intraoperative complication (0.3%), a premature closure of the incision before repair of the vastus medialis, was identified. There were 141 postoperative complications (138 surgical, 3 medical) in 118 patients for a complication rate of 34.3%. The most common complications were stiffness requiring a nonstandard-of-care intervention (16.3%), superficial wound infection/wound dehiscence (8.1%), and hemarthrosis/effusion requiring aspiration (5.8%). Patients experiencing postoperative complications were older (mean difference, 3.49 years; 95% CI, 1.26-5.73 years; P = .002), had a higher mean Charlson Comorbidity Index (mean difference, 0.26; 95% CI, 0.08-0.45; P = .006), and were more likely to be current smokers (P = .015) compared with patients with no complications. Inpatient surgery (defined as surgery in a hospital setting with at least 1 overnight stay) was associated with postoperative complications (odds ratio [OR], 2.29; 95% CI, 1.39-3.77; P = .001); this association remained significant generation of a multivariate model (OR, 2.07; 95% CI, 1.19-3.58; P = .010). Previous surgery on the ipsilateral knee (P < .001) and concomitant autologous chondrocyte implantation (P = .046) were also associated with postoperative complications. Conclusion: The study findings indicated a low intraoperative complication rate (0.3%) and a relatively high early postoperative (≤90 day) complication rate (34.3%) after TTO. Variables associated with postoperative complications included greater age, higher Charlson Comorbidity Index, surgery in an inpatient setting, previous surgery on the ipsilateral knee, and concomitant autologous chondrocyte implantation.

Using Dual-Orthogonal Fluoroscopy and CT to Assess the Relationship Between Knee Morphology and Patellar Kinematics in Patients With Patellofemoral Pain.

INTRODUCTION: Patellofemoral pain (PFP) is one of the most common knee overuse injuries, with studies suggesting PFP as a precursor for early knee osteoarthritis. The etiology of PFP is multi-factorial; however, patellar mal-tracking has been regarded as a primary mechanism. Details of this multi-factorial mechanism have been unclear because of the limitations in evaluating in-vivo, three-dimensional (3D) patellofemoral joint movement during dynamic activities accurately. Alternatively, studies have demonstrated the high accuracy and repeatability of dual fluoroscopy and CT/MRI for measuring knee joint motion. OBJECTIVE: This study uses dual fluoroscopy and CT to investigate the associations between joint morphology and patellar kinematics in healthy controls and subjects with PFP. METHODS: Eight PFP females (29.7±10.6 years) and 10 healthy females (25.0±7.7 years) were recruited and screened by a sports medicine physician. CT imaging was performed on participants in a supine with the knee extended, and ankle and hip in neutral alignment. Dual-orthogonal fluoroscopy measured patellar movement while participants performed a lunge task. A calibration algorithm was used to register the 3D CT model to 2D fluoroscopy image to calculate the relative position and angles of the patella based on the clinical definition of patellar motion. Measures of patellar and trochlear morphology were generated and correlated to kinematic data. RESULTS AND CONCLUSION: There was a significant difference in the patellar-to-trochlear width ratio; however, no other significant differences in CT morphology measurements were present between groups. For PFP patients in the weight-bearing extended position, there was a moderate positive correlation between the patellar-to-trochlear width ratio and medial-lateral patellar shift (τ = 0.643, p = 0.026). Healthy controls in this position demonstrated a moderate positive correlation between the lateral-trochlear inclination angle and medial-lateral patellar shift (τ = 0.600, p = 0.016) and moderate negative correlation between medial trochlear inclination angle and medial-lateral patellar shift (τ = -0.511, p = 0.040). The findings suggest that, for this cohort, there is correlation between morphology and patellar kinematics. Passive and active stabilizers likely have a role in mal-tracking.

Should isolated superolateral Hoffa's fat pad edema identified by MRI be reported or ignored in adolescent patients?

BACKGROUND AND OBJECTIVE: The presence of superolateral Hoffa's fat pad (SHFP) edema is associated with several morphometric measurements related to patellar alignment and trochlear morphology. Our aim is to evaluate management implications in adolescent patients with isolated superolateral Hoffa's fat pad edema on MRI. MATERIALS AND METHODS: Retrospective review of 117 adolescents with knee MRI (mean 14.8 years old) with isolated superolateral Hoffa's fat pad edema. Patients with edema were separated into two groups based on the number of MRI axial slices involved with edema: group 1 (G1) of 27 patients with 1 slice vs group 2 (G2) of 90 patients with 2 or more slices. A comparison control group was used (45 patients who had normal MRI knees). Data points included % referral for physical therapy (PT) or surgery, Hoffa's fat pad edema, tibial tubercle-trochlear groove (TT-TG) distance and lateral trochlear inclination (LTI) angle. Fisher's exact and independent t-tests, ANOVA and regression models were used for statistical analysis. RESULTS: There is statistically significant difference between Hoffa's fat pad edema patients and control regarding PT referral with G1: 70%, G2: 76%, and control: 53% (p = 0.03). There is statistically significant difference between these groups regarding TT-TG measurements with higher values in edema groups; G1: 11.9 mm±4.1, G2 13 mm ±4.1, and control 8.7 mm±3.6, (p = 0.001). There was a statistically significant association between edema and increased TT-TG distance (p = 0.001) but not LTI angle (p = 0.2). CONCLUSION: MRI identification of isolated superolateral Hoffa's fat pad edema is positively associated with TT-TG distance and its presence is associated with higher referral rates to physical therapy for patella maltracking.

Management of patella maltracking after total knee arthroplasty: a systematic review.

PURPOSE: Patella maltracking is among the most frequent causes of poor outcomes and early failure after total knee arthroplasty (TKA), with an incidence that ranges from 1 to 20%. Even if there is agreement between authors regarding the preoperative and intraoperative management of patella maltracking in TKA, less clear are postoperative conducts. The purpose of this systematic review is to summarize and compare surgical techniques used to treat patella maltracking after TKA. METHODS: A systematic review of the literature was performed with a primary search on Medline through PubMed. The PRISMA 2009 flowchart and checklist were used to edit the review. Screened studies had to provide clinical, functional and radiological results and complications of the proposed treatment to be included in the review. RESULTS: A total of 21 articles were finally included. Three main types of surgical procedures and other minor techniques have been identified to manage patella maltracking after TKA. The choice of the proper technique to use in the specific case depends on several factors, first of all the malpositioning of the prosthetic components. CONCLUSION: Patella maltracking after TKA represents a frequent and challenging problem for orthopedic surgeons. Treatments described in the literature are often able to correct an abnormal patellar tracking; nevertheless, authors report variable percentages of residual knee pain and dissatisfaction in re-treated patients. Therefore, it would be desirable to prevent the maltracking condition at the time of primary arthroplasty, using proper surgical precautions.

Botulinum neurotoxin type A improves vasti muscle balance, patellar tracking, and pain in patients with chronic patellofemoral pain.

The purpose of this study was to determine the effects of botulinum neurotoxin type A (BoNT-A) on vastus lateralis:vastus medialis (VL:VM) muscle balance, patellar tracking, and pain in patients with chronic patellofemoral (PF) pain. We recruited 13 participants (9 females, 4 males) with recalcitrant PF pain who underwent ultrasound-guided BoNT-A injections into the distal third of the VL muscle, followed by a 6-week home exercise program to strengthen their VM muscle. We imaged the participants in a C-arm computed tomography (CT) scanner before and after the intervention. We calculated VL:VM ratios from CT images from a supine, nonweight-bearing condition. We obtained patellar tilt and bisect offset values from CT images from an upright, weight-bearing condition. We recorded functional pain scores before, immediately after, and 2-4 years after the intervention. We classified the participants into normal tracking and maltracking groups based on their patellar tilt and bisect offset values. BoNT-A with home exercise reduced VL:VM ratio (18%; p < 0.001), patellar tilt (19%; p = 0.020), and bisect offset (5%; p = 0.025). Four participants classified as maltrackers before the intervention transitioned to normal tracking after the intervention. Functional pain scores improved immediately after the intervention (13%, p < 0.001) and remained improved at 2-year follow-up (12%, p = 0.011). Statement of Clinical Significance: This study provides new evidence in support of BoNT-A for treatment of PF pain. Classification of patients under weight-bearing conditions may identify individuals who will most benefit from a BoNT-A treatment.

Revision lateralization osteotomy of the tibial tubercle has excellent outcomes in patients suffering from previous medial tibial tubercle overcorrection.

INTRODUCTION: Tibial tubercle osteotomy (TTO) is a common procedure used to treat patients with patellofemoral instability (PFI) and osteoarthritis (PFOA). Medial patellar maltracking due to previous excessive medialization of the tibial tubercle has rarely been reported. Therefore, the goal of this study was to assess patient-reported outcome measures (PROMs) after revision osteotomy with lateralization of the tibial tubercle (RL-TTO) to correct medial patellofemoral maltracking. MATERIALS AND METHODS: Between 2017 and 2021, a series of 11 patients (male/female 1/10; age 35.8 ± 10.5 years) were treated by RL-TTO, of whom 8 patients could be retrospectively evaluated after a mean of 32.4 ± 15.1 months (range 18-61 months) postoperatively. The Kujala anterior knee pain scale, the patellofemoral subscale of the Knee Osteoarthritis and Outcome Score (KOOS-PF), and a numeric analog scale (NAS; 0-10) regarding anterior knee pain (AKP) at rest and during activity were assessed from pre- to postoperatively. RESULTS: The preoperative mean tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-posterior cruciate ligament (TT-PCL) distances were - 6.5 ± 6.5 mm and 0.7 ± 4.6 mm, respectively. The intraoperatively determined amount of tibial tubercle lateralization averaged 10.7 ± 3.6 mm. The Kujala score and KOOS-PF improved significantly from 33.6 ± 10.1 (23-51) points to 94.4 ± 6.2 points (82-100) (p < 0.001) and from 20.6 ± 13.2 points (0-43.3) to 87.3 ± 9.9 points (72.8-100) (p < 0.001) from pre- to postoperatively, respectively. Pain at rest decreased from 5.8 ± 1.9 to 0.8 ± 0.9 (p < 0.001), and pain during activity decreased from 8.6 ± 1.3 to 1.6 ± 1.5 (p < 0.001). CONCLUSION: RL-TTO significantly improved subjective knee function and AKP in patients suffering from medial patellar maltracking due to previous excessive tibial tubercle medialization osteotomy at short-term follow-up.

Failure modes in malrotated total knee replacement.

PURPOSE: Achieving normal rotational alignment of both components in total knee arthroplasty (TKA) is essential for improved knee survivorship and function. However, malrotation is a known complication resulting in higher revision rates. Understanding malrotation of the components and its concomitant clinical and functional outcomes are important for early diagnosis and management. The purpose of this study was to evaluate the effect of malrotation on clinical outcomes and failure modes in both single and combined rotational malalignment. METHODS: From our hospital database of 364 revisions, a cohort of 76 knees with patellar maltracking, stiffness, reduced range of motion and early aseptic failure were reviewed and investigated for component malrotation using computed tomography following Berger protocol. CT findings confirmed component malrotation in 70 of these patients. Investigations included (1) measurement of femoral component malrotation using surgical transepicondylar axis, (2) measurement of tibial component malrotation using anteroposterior axis and (3) measurement of combined component rotational errors. RESULTS: The correlation of CT analysis and clinical outcomes after primary TKA revealed association of patellar maltracking with femoral internal rotation, pain and instability with tibial internal rotation and knee stiffness in patients with combined component malrotation as the commonest mode of presentation. Our study showed that patients with isolated femoral, tibial and combined malrotation presented at a mean period of 3.4 ± 1.34, 1.7 ± 0.8 and 2.3 ± 0.69 years, respectively, after the index surgery. Post-revision, the mean Knee Society Score and Oxford Knee Score improved from 29.1 to 78.7, and 10.5 to 32.8, respectively, and the mean range of motion improved from 74.9 ± 24.8 to 97.1 ± 12.7 degrees at a mean follow-up of 42 months. CONCLUSION: Early detection of malrotation in TKA and its management with revision of both components can lead to better clinical and functional outcomes. LEVEL OF EVIDENCE: III.

The Influence of Surgical Realignment Procedures on Dynamic Patellar Tracking: A Dynamic Magnetic Resonance Imaging-Controlled Feasibility Study.

Persisting patellar maltracking following surgical realignment often remains unseen. The aim of this study was to analyze the effects of realignment procedures on patellofemoral kinematics in patients with patellofemoral instability (PFI) and patellofemoral maltracking (PM) by using dynamic magnetic resonance imaging (MRI). Patients planned for surgical patellar realignment due to PFI and a clinically and radiologically apparent PM between December 2019 and May 2022 were included. Patients without PM, limited range of motion, joint effusion, or concomitant injuries were excluded. Dynamic mediolateral translation (dMPT) and patella tilt (dPT) were measured preoperatively and three months postoperatively. In 24 patients (7 men, 17 women; mean age 23.0 years), 10 tibial tubercle transfers, 5 soft tissue patella tendon transfers, 6 trochleoplasties, 3 lateral lengthenings, 1 varizating distal femoral osteotomy (DFO), and 1 torsional DFO were performed. At final follow-up, dMPT (from 10.95 ± 5.93 mm to 4.89 ± 0.40 mm, p < 0.001) and dPT (from 14.50° ± 10.33° to 8.44° ± 7.46°, p = 0.026) were significantly improved. All static radiological parameters were corrected to physiological values. Surgical patellar realignment contributed to the significant improvement of patellofemoral kinematics, with an approximation to normal values. The postoperative application of dynamic MRI allowed for a quantification of the performed correction, allowing for a postoperative control of success.

The Increased Tibiofemoral Rotation: A Potential Contributing Factor for Patellar Maltracking in Patients with Recurrent Patellar Dislocation.

OBJECTIVE: The purpose of this study was to analyze the relationship between tibiofemoral rotation and patellar maltracking in patients with recurrent patellar dislocation. METHODS: A total of 143 consecutive knees (118 patients) with clinically diagnosed recurrent patellar dislocation from January 2018 to December 2019 were retrospectively analyzed. Patellar tilt angle and bisect offset index were recorded on axial CT to assesses the severity of patellar maltracking. Tibiofemoral rotation angle is measured by comparing the angle between the posterior femoral and tibial condylar lines on three-dimensional CT. The Pearson correlation was calculated to investigate the association between tibiofemoral rotation angle and patellar maltracking. Patients were divided into the rotation group (≥15°) and control group (<15°) based on the value of tibiofemoral rotation and a further comparison was performed. To further clarify the complicated relationship among tibial tubercle-trochlear groove (TT-TG), tibial tubercle-posterior cruciate ligament distance (TT-PCL), tibiofemoral rotation, and patellar maltracking, patients were divided into four subgroups according to the value of TT-TG and TT-PCL. RESULTS: The mean preoperative tibiofemoral rotation angle was 12° ± 6° (range, 0°-31°). Pearson correlation between patellar maltracking parameters (bisect offset index, patellar tilt angle) and various bony deformities found that the tibiofemoral rotation angle was moderately correlated with bisect offset index (r = 0.451, p < 0.001) and patellar tilt angle (r = 0.462, p < 0.001). Further results demonstrated that bisect offset index (152.1 vs 121.2, p < 0.001) and patellar tilt angle (41.2° vs 33.5°, p < 0.001) were significantly higher in the rotation group than that in control group. For patients with a TT-TG distance of >20 mm, the increased TT-TG distance was mainly caused by tibiofemoral rotation angle in group C (TT-TG > 20 mm, TT-PCL < 24 mm) and predominantly induced by tibial tubercle lateralization in group D (TT-TG > 20 mm, TT-PCL > 24 mm). Bisect offset index and patellar tilt angle were significantly higher in the group C than group D. CONCLUSION: The increased tibiofemoral rotation angle is associated with patellar maltracking in patients with recurrent patellar dislocation. Patients with increased tibiofemoral rotation angle usually have more severe patellar maltracking.

Dynamic Mediolateral Patellar Translation Is a Sex- and Size-Independent Parameter of Adult Proximal Patellar Tracking Using Dynamic 3 Tesla Magnetic Resonance Imaging.

PURPOSE: To provide normal values for physiological patellofemoral tracking in a representative group of healthy individuals, as well as sex differences, using real-time 3T-magnetic resonance imaging (MRI) and to test for the reliability of the presented technique. METHODS: One hundred knees of healthy individuals with no history of patellofemoral symptoms were scanned with dynamic MRI sequences, during repetitive cycles of flexion (40°) and full extension. Within a 30-seconds time-frame, three simultaneous, transverse slices were acquired. Dynamic mediolateral patellar translation (dMPT) and dynamic patellar tilt (dPT) were measured on two occasions by two independent examiners. Common radiological parameters were measured using static MRI, and correlations were calculated. RESULTS: 100 knees (53 right, 47 left; age: 26.7 ± 4.4 years; BMI: 22.5 ± 3.1) of 57 individuals (27 females, 30 males) were included. Mean height was 170.1 ± 7.7 cm in women and 181.8 ± 6.4 cm in men. Average patella diameter was 37.9 ± 2.7 (95% CI 37.1-38.7) mm in women and 42.4 ± 3.2 (95% CI 41.5-43.3) mm in men. In females, the patellar diameters and intercondylar distances were significantly smaller than in males (P < .001). Radiological parameters for patellar maltracking were within the normal range. During the range of motion, mean dMPT was 1.7 ± 2.4 (95% CI .9-2.5) mm in females and 1.8 ± 2.7 (95% CI 1.1-2.6) mm in males (P = .766). Mean dPT was 1.3 ± 2.9° (95% CI .4-2.1°) in females and -0.2 ± 3.8° (95% CI -1.2-.9°) in males (P = .036). Neither dMPT nor dPT was correlated with height, BMI, or patellar diameter. Intercondylar distance correlated weakly with dPT (r = -.241; P = .041). Intra- and interrater reliability were excellent for dMPT and dPT. CONCLUSION: Dynamic mediolateral patellar translation is a size- and sex-independent parameter for proximal patellar tracking. In healthy individuals without patellofemoral abnormalities normal dMPT proximal to the trochlea groove was 1.7 ± 2.5 (1.2-2.2) mm, independent of size or sex. Normal dPT showed a dependency on sex and was 1.3 ± 2.9 (.4-2.1)° in women and -0.2 ± 3.8 (-1.2-0.9)° in men. LEVEL OF EVIDENCE: Level II, diagnostic study.

Evaluating Patellofemoral Patients: Physical Examination, Radiographic Imaging, and Measurements.

Patellofemoral pain is one of the most common symptoms of patients presenting to sports medicine clinics. Obtaining a pertinent history and performing a thorough examination is crucial to identifying the subset of patients with instability who are most likely to benefit from surgical stabilization. A comprehensive radiographic work-up that includes standard radiographs and advanced imaging helps elucidate the diagnosis and provides crucial information for preoperative planning. This article reviews the evaluation, physical examination, and interpretation of radiographic imaging of patients with patellofemoral pain as an introduction to subsequent articles in this issue discussing surgical interventions.

Coronal Malalignment-When and How to Perform a Tibial Tubercle Osteotomy.

Coronal malalignment of the patellofemoral joint may contribute to both instability as well as pain and joint overload. The use of distal realignment procedures has evolved to include uniplanar and multiplanar osteotomies, which allows patient-specific treatment. With a careful understanding of the complex pathoanatomy, including osseous, soft tissue, and dynamic muscular factors, an appropriately designed tibial tubercle osteotomy (TTO) is an invaluable tool for the orthopedic surgeon to improve joint biomechanics and off-load articular injuries. Current techniques have improved TTO surgery to limit complications and produce reliably good results.