Search Results (93)

Background/Objectives: Lateral patellar dislocation (LPD) is a common pathology of the adolescent knee and a major predisposing factor for patellofemoral instability (PFI). The pathogenesis of PFI involves a combination of anatomical and biomechanical contributors, with increasing evidence pointing to sex-specific differences in knee morphology. Despite this, the developmental course of these parameters and their variation between sexes remain insufficiently characterized. This study aims to investigate sex-related differences in patellofemoral joint geometry among skeletally immature patients with a history of PFI, focusing on how these anatomical variations evolve with increasing knee size, as represented by femoral condylar width. Methods: A total of 315 knee MRIs from patients under 18 years with documented PFI were retrospectively analyzed. Trochlear morphology, patellar tilt, axial positioning, and sagittal alignment were assessed using established MRI-based parameters. All measurements were normalized to bicondylar width to account for individual knee size. Sex-specific comparisons were performed using independent t-tests and linear regression analysis. Results: Females exhibited significantly smaller femoral widths, shallower trochlear depth (TD), shorter tibial tubercle–posterior cruciate ligament (TTPCL) distances, and lower patellar trochlear index (PTI) values compared to males (p < 0.05). In males, increasing femoral width was associated with progressive normalization of patellar tilt and sagittal alignment parameters. In contrast, these alignment parameters in females remained largely unchanged or worsened across different femoral sizes. Additionally, patellar inclination angle and PTI were significantly influenced by knee size in males (p < 0.05), whereas no such relationship was identified in females. Conclusions: Sex-specific morphological differences in patellofemoral geometry are evident early in development and evolve distinctly with growth. These differences may contribute to the higher prevalence of PFI in females and underscore the importance of considering sex and knee size in anatomical assessments. Full article

Background: Primary patellar dislocation is a relatively uncommon knee injury but carries a high risk of recurrence, particularly in young and physically active adolescent individuals. Anatomical features of the patellofemoral joint have been implicated as key contributors to instability. The purpose of this study was to evaluate anatomical risk factors associated with recurrent patellar dislocation following a primary traumatic event, using MRI-based parameters. Methods: Fifty-four patients who sustained a first-time lateral patellar dislocation were included. MRI was used to measure tibial tuberosity–trochlear groove (TT–TG) distance, tibial tuberosity–posterior cruciate ligament (TT–PCL) distance, Insall–Salvati ratio (IS), sulcus angle (SA), patellar tilt angle (PTA), patella length, and patellar tendon length. Trochlear dysplasia was assessed according to the Dejour classification. Recurrence was defined as a subsequent dislocation occurring within three years of the primary injury. Results: Significant differences were observed in TT–TG distance and patellar tendon length (p < 0.05). Patients with recurrent dislocation had lower TT–TG values and shorter patellar tendon lengths. Other parameters, including PTA, IS, and patella height, did not show statistically significant differences. Conclusion: Anatomical factors may contribute to the risk of recurrent patellar dislocation. Identifying these variables using imaging may support clinical decision making and guide individualized treatment plans following primary injury. Full article

Background/Objectives: Several studies have described the changes in tibiofemoral rotation (TFRA) and patellar tilt angle (PTA) following total hip arthroplasty (THA). However, no studies have applied three-dimensional measurements to evaluate leg lengthening, changes in global femoral offset (GFO) or TFRA, or PTA during THA. Accordingly, this study employs three-dimensional measurements to test our hypothesis that increased leg lengthening is associated with an increase in TFRA, which increases PTA and worsens postoperative m-Harris Hip Score (mHHS). Methods: A total of 111 consecutive patients who underwent THA were enrolled. THA-related changes in GFO, femoral version, TFRA, PTA, and leg lengthening. Relationships between each parameter and the m-Harris Hip Sc were also assessed using the intraclass correlation coefficient. Results: Leg lengthening was significantly positively correlated with changes in TFRA and PTA. However, changes in GFO negatively correlated with changes in TFRA and PTA. Moreover, changes in GFO and leg lengthening were the only factors affecting changes in TFRA and PTA, respectively. Conclusions: Direct relationships exist between changes in GFO and changes in TFRA and PTA. This may be related to increased tension of the adductor muscles and medial soft tissue around the knee, ultimately reducing strain on the patellofemoral joint and improving knee pain. Full article

Background/Objectives: Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition that causes anterior knee pain, often linked to increased joint stress. Rehabilitation typically includes education, strength training, and functional exercises. Recently, telerehabilitation has become a promising alternative, particularly useful in improving access to care in rural areas. This study compares the effects of supervised (SE), web-based (WBE), and self-guided (SGE) exercise programs on pain, functionality, and fear of movement (kinesiophobia) in individuals with PFPS. Materials and Methods: Sixty female patients with PFPS participated in this randomized controlled trial. They were randomly assigned to one of three groups: SE, WBE, or SGE. Each program lasted six weeks, with exercises adjusted based on individual tolerance. Outcomes were assessed using the Kujala Anterior Knee Pain Scale, the visual analog scale (VAS) for pain, the Timed Up and Go Test (TUG) for mobility, and the Tampa Kinesiophobia Scale. Results: All groups showed significant improvements in pain, functionality, and kinesiophobia (p < 0.05). The SE group achieved the greatest improvements across all measures, reducing pain and kinesiophobia while enhancing functionality (p < 0.017). The WBE group also showed significant improvements, outperforming the SGE group in all outcomes (p < 0.017). The SGE group demonstrated the least improvement but still achieved positive changes. Conclusions: Supervised exercise programs were the most effective in managing PFPS symptoms. However, the web-based programs also provided substantial benefits, making them a viable option when in-person supervision is not feasible. Future research should aim to enhance digital interventions for broader accessibility and engagement. Trial Registration: The study protocol was also registered on ClinicalTrials.gov (NCT06625086). Full article

Background/Objectives: Optimal activation of the quadriceps femoris, particularly the vastus medialis, while minimizing excessive activation of the vastus lateralis, is crucial for treating knee injuries like ACL ruptures and patellofemoral pain syndrome. Restoring proper muscle balance may enhance rehabilitation outcomes, but effective strategies for modulating muscle activity remain unclear. High-velocity low-amplitude hip manipulation has shown potential to influence neuromuscular function, yet its impact on quadriceps activation during knee extension has not been well studied. Therefore, the main aim of this study is to examine the effects of a single session of high-velocity low-amplitude hip manipulation on quadriceps femoris muscle activation and maximum voluntary contraction during knee extension. Methods: This study utilizes a randomized controlled design. Thirty physically active men and women (mean age: 21.9 ± 1.7 years) were randomly assigned to either an experimental group (n = 15; receiving hip joint manipulation) or a control group (n = 15; undergoing a sham intervention). Participants in the intervention group received a treatment involving hip manipulation and short-duration traction. Muscle activity of the rectus femoris, vastus lateralis, and vastus medialis was assessed using surface electromyography before and after the intervention, while muscle performance was measured by evaluating isometric knee extension strength in the lower limb. The isometric strength test was conducted in a seated position with the knee flexed at 60 degrees in Biodex System 4. Results: This study finds that the experimental group had significantly higher vastus lateralis mean amplitude (p = 0.020; effect size = 0.186) and vastus medialis mean amplitude (p < 0.001; effect size = 0.577) of electromyography root mean square electromyography compared to the control group. The experimental group also showed greater vastus medialis max amplitude (p < 0.001; effect size = 0.435). No significant differences were noted for rectus femoris mean amplitude (p = 0.078; effect size = 0.110), vastus lateralis max amplitude (p = 0.363; effect size = 0.031), rectus femoris max amplitude (p = 0.069; effect size = 0.117), or median frequency of the raw electromyography signal across muscle groups. Conclusions: In conclusion, high-velocity low-amplitude hip manipulation significantly enhances vastus medialis activation, highlighting its potential to improve quadriceps balance. These findings support the incorporation of hip manipulation into rehabilitation protocols. Full article

This review explores the technological advancements in, engineering considerations regarding, and quality standards of veterinary patellar groove replacement implants. Veterinary-specific regulations for these implants are currently lacking. Therefore, human knee implant benchmarks are used as references. These benchmarks guide evaluation of the surface quality, material selection, biocompatibility, and mechanical performance of the implant to ensure reliability and longevity. Patellar luxation is a common orthopedic disorder in small animals which leads to patellofemoral joint instability and cartilage degeneration, and is often caused by angular limb deformities that disrupt patellar alignment. In severe cases, patellar groove replacement is necessary to restore function and alleviate pain. The implant materials must provide durability, mechanical strength, and biocompatibility to withstand joint forces while ensuring minimal wear. High-quality surface finishes reduce the friction experienced by these materials, improving their long-term performance. Advances in 3D printing allow the creation of patient-specific implants. These implants offer an enhanced anatomical fit and enhanced functionality, which is especially beneficial in complex cases. However, challenges remain in achieving consistent manufacturing quality and economic feasibility. While custom implants are invaluable for difficult cases, standardized designs are sufficient for routine applications. Combining human implant standards with new manufacturing technologies improves veterinary orthopedic solutions. This integration expands the treatment options for patellar luxation and enhances the quality and accessibility of implants. Full article

Background/Objectives: Patellofemoral pain (PFP) is believed to be a precursor to knee osteoarthritis (OA). The primary purpose of this study was to compare matrix metalloproteinase-9 (MMP-9) levels in young adult females with and without PFP. The secondary purpose was to determine the associations between MMP-9, patella position, hip and knee kinematics, and pain in females with PFP. Methods: Plasma was analyzed for MMP-9. Patellar position was measured using diagnostic ultrasound as the degree of offset (RAB angle) from the deepest aspect of the femoral trochlear groove to the inferior pole of the patella. A positive RAB angle suggested patella lateralization. Hip and knee kinematics during a single-leg squat were measured using 2-dimensional motion analysis and quantified as the dynamic valgus index (DVI), a combined measure of hip and knee motion. A higher DVI suggests increased valgus loading at the patellofemoral joint. Pain was measured using a 10 cm visual analog scale. Results: Females with PFP had significantly higher levels of MMP-9 than controls (72.7 vs. 58.0 ng/mL, p = 0.03). Females with PFP had a significant positive association between MMP-9 and patella lateralization (r = 0.38, p = 0.04), suggesting that greater patellar lateralization may contribute to increased joint inflammation. A significant inverse association was observed between MMP-9 and the DVI (r = −0.50, p = 0.007), indicating that individuals with higher inflammatory marker levels may adopt movement patterns that reduce valgus loading. Conclusions: The significant association between MMP-9 and patella lateralization suggested a potential link between patella alignment and joint inflammation, which may contribute to early joint degeneration. The inverse association between MMP-9 levels and the DVI suggested that subjects with higher MMP-9 levels adjusted their movement pattern as a compensatory mechanism to reduce knee valgus stress to reduce joint degeneration. Full article

Background: Patellofemoral instability is a pathological condition that is characterized by altered joint congruence, which manifests as episodes of subluxation or dislocation of the patella. The aim of this study was to systematically review the literature on this condition by comparing the results of various studies evaluating the effectiveness of surgical versus conservative treatment approaches for patellar instability, particularly in patients experiencing a first episode of patellar dislocation. Methods: The research was conducted using three different databases: PubMed, Cochrane Library, and PEDro. Both randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) with full text availability were included. All articles were in English, and no temporal limits were imposed during the search. Results: In total, 10 articles met the inclusion criteria and were included in the systematic review. The standard for statistical significance was p < 0.05. The statistical analysis of re-dislocation rates indicated a statistically significant difference between the conservative and surgical groups (p = 0.023). The statistical analysis also showed that the mean Kujala score was significantly lower in the non-operative group (80.94) than the surgical group (89.83) (p = 0.017). These results indicate that surgical treatment is significantly more effective in reducing re-dislocation rates than conservative treatment and has better Kujala scores than conservative treatment. Conclusions: A reduction in the re-dislocation rate and improved scores on subjective tests related to pain and quality of life were observed with surgical treatment. Nevertheless, a higher level of evidence is needed to more clearly and accurately determine the most effective treatment approach. Full article

High-level (HL) and low-level (LL) competitive aerobics athletes demonstrate different landing patterns during rotational jump landings, resulting in differing risks of lower limb injuries. This research aimed to investigate biomechanical differences between different levels of competitive aerobics athletes during rotational jump landings. The subjects included 15 male HL athletes and 15 LL athletes. This study captured kinematics, kinetics, muscle activation, and muscle force data, calculating joint stiffness, energy dissipation, anterior tibial shear force (ATSF), and patellofemoral joint contact force (PTF). LL athletes demonstrated significantly greater ankle dorsiflexion, inversion, and internal rotation angles; knee abduction angle and moment, internal rotation angle and moment; and smaller ankle plantarflexion moment and knee flexion angle. They also showed lower calf muscle coactivation, PTF, joint stiffness at the knee and hip, and the energy dissipation of the ankle and lower limb; greater thigh muscle coactivation and ATSF. The results show that LL athletes exhibit poorer stability at the ankle and knee joints, with a higher risk of anterior cruciate ligament (ACL) and ankle inversion injuries during rotational jump landings. To lower these risks, LL athletes should increase the flexion angle of the knee, hip, and ankle plantarflexion during landing. Full article

Background/Objectives: The diagnostic guidelines for pediatric patellofemoral instability (PFI) remain incomplete. PFI remains a challenging issue as it affects the biomechanics of the knee joint, triggers anterior knee pain, and is linked to the development of early-onset osteoarthritis. The diagnostic process is complicated by numerous anatomical factors that must be considered. This review aims to consolidate current knowledge presented in the literature on radiological diagnostics for PFI in pediatric populations, with the application of all imaging techniques—including ultrasonography (US), magnetic resonance imaging (MRI), computed tomography (CT), and radiography (RTG)—which enable the evaluation of anatomical risk factors critical for the diagnosis, prevention, and treatment of PFI. Methods: A search of the PubMed/MEDLINE database was conducted to identify relevant studies from 1975 to 2024. The search terms were as follows: (patellar or patella) and (instability or displacement or dislocation) and (diagnostic or diagnosis or imaging or radiographic). A total of 2743 articles were retrieved, which were screened to yield 29 studies for further review. These studies were then divided into seven categories regarding the diagnostic methods: risk factors, tibial tubercle trochlear groove (TT-TG)/tibial tubercle posterior cruciate ligament (TT-PCL), MPFL injury and cartilage damage, patella and trochlear dysplasia, torsional abnormalities, coronal plane alignment, and genetics. Results: The methods presented statistically significant differences, with those most commonly used for the diagnosis of patella dislocation being TT-TG index, MPFL rapture, and trochlear dysplasia. Conclusions: In summary, multiple diagnostic tools, including MRI, CT, X-ray, and physical examination, are available for the assessment of PFI, each contributing to treatment decisions. Although MRI remains the primary diagnostic tool, further research is needed to establish more precise diagnostic criteria. Full article

The development of an instrumented patellar prosthesis, able to measure the contact forces at the patellofemoral joint, can significantly aid in investigating the causes of total knee arthroplasty failures due to patellar complications. This study focuses on developing and validating an instrumented patellar prosthesis to measure contact forces in the patellofemoral joint. A piezoresistive force sensor was characterized and integrated into a conditioning circuit, with the aim of its implementation in the prosthesis. To measure medial and lateral forces independently, the sensors were trimmed in half. Compression tests (up to 2000 N) assessed sensor performance in terms of linearity (R² = 0.998 intact vs. 0.989 trimmed), repeatability (0.9% intact vs. 0.8% trimmed), and accuracy (1.7% intact vs. 2.3% trimmed) for forces up to 250 N. Higher force levels resulted in increased errors, but at a rate still comparable to that of existing sensors in the literature. Key considerations for the design of the instrumented prosthesis, such as minimizing point and shear loads, were identified. A prototype prosthesis capable of housing the sensor was proposed. The integrated system shows potential for improving the understanding of Total knee arthroplasty (TKA) failures through in vitro studies and could serve as an intraoperative tool for the evaluation of bone resections. Full article

The biomechanical mechanism of postoperative patellofemoral joint (PFJ) complications after open-wedge high tibial osteotomy (OWHTO) has not been investigated. This study was to determine the length changes in the patellar tendon (PT), medial patellotibial ligament (MPTL), medial patellofemoral ligament (MPFL), and quadriceps moment arm (QMA) during staircase motion before and after OWHTO. Computed tomography (CT) scans of 15 patients’ lower extremities were used to reconstruct three-dimensional models, and magnetic resonance imaging (MRI) of the knee and hip joints was used to mark the soft tissue footprints. Then, such soft tissue lengths were quantified by a dual fluoroscopic imaging system (DFIS). Additionally, function scores were used to assess patient outcome changes. The results showed that there was a contraction of the PT after OWHTO due to its adhesion to the osteotomy site, causing PT length to be negatively correlated to the open-wedge angle. In addition, the shortening of the MPTL and QMA caused patellar instability and an imbalance in the strength of the lower extremities. Additionally, most knee function scores improved after OWHTO, except the Feller scores. Multiple methods should be considered to optimize surgical procedures, postoperative rehabilitation, and physical therapy. Full article

Background: Patellofemoral pain (PFP) is one of the most common multifactorial musculoskeletal pathologies affecting the knee joint. The prevalence of PFP in the general population ranges from 11% to 17%, with higher rates observed in specific groups such as females, runners, military personnel, and young athletes. To assess symptoms associated with PFP, the patellofemoral subscale (KOOS-PF) was developed, consisting of 11 questions that evaluate pain, stiffness, and quality of life. The KOOS-PF scale has already been validated and shown to be reliable in both its Spanish and Arabic versions. Objectives: The aim of this study was to assess the reliability and validity of the KOOS-PF scale in the Greek language among the Greek population with patellofemoral pain. Methods: Fifty-five participants aged 18–65 years who suffered from PFP were evaluated in two phases on the first and third days to determine the reliability and validity of the measures of KOOS-PF in the Greek language. Construct validity was assessed using the knee outcome survey scale—activities of daily living scale (KOS-ADLS). Reliability was measured through repeated measurements (test–retest) using intraclass coefficient correlation (ICC), standard error of measurement (SEM), and smallest detectable difference (SDD). Internal consistency was evaluated using Cronbach’s coefficient a. The significance level was set at 5% (α = 0.05). Results: The KOOS-PF measures showed high internal consistency reliability (Cronbach’s alpha 0.87, p = 0.05) and high test–retest reliability (ICC = 0.95, p = 0.05, SEM = 3.7, SDC = 13.57). Additionally, the Greek version of the KOOS-PF exhibited high construct validity when correlated with the KOS-ADLS scale (r = 0.72, p = 0.001). Conclusions: The KOOS-PF scale displayed high reliability and construct validity for measuring patellofemoral pain in the Greek population. Full article

While several studies have reported short-term clinical outcomes after medial patellofemoral ligament (MPFL) repair with suture tape augmentation, there is still a dearth of knowledge regarding midterm clinical outcomes. This study aimed to evaluate the midterm clinical outcomes of MPFL repair with suture tape augmentation in patients with patellar dislocation. We retrospectively reviewed the clinical records of patients who underwent MPFL repair with suture tape augmentation for at least one episode of patellar dislocation between 2015 and 2020. Patient-reported clinical outcomes (PROs) were evaluated via the International Knee Documentation Committee (IKDC) score and the knee injury osteoarthritis outcome score (KOOS). In total, 17 knees (4 males and 13 females) who underwent MPFL repair with suture tape augmentation with a mean follow-up of 54.6 ± 19.5 months were included in this study. PROs significantly improved from preoperatively to the final follow-up (IKDC score: 50.7 ± 26.6 vs. 88.8 ± 13.0, p < 0.001; KOOS: 68.8 ± 23.3 vs. 91.2 ± 8.4, p = 0.011) without reducing the patient’s activity level at the final follow-up (UCLA AS score: 7.9 ± 2.4 at preinjury vs. 7.9 ± 2.2 at the final follow-up, p = 0.655). Subgroup analysis revealed good postoperative outcomes, regardless of the patient’s skeletal maturity or the presence or absence of generalized laxity. In conclusion, MPFL repair with suture tape augmentation is a safe and effective treatment for midterm follow-up. Full article

Background/Objectives: After open-wedge high tibial osteotomy (OWHTO), the patella is displaced distally, causing patellofemoral joint degeneration. The objective of this study was to ascertain whether the combination of OWHTO and lateral retinacular release (LRR) can prevent articular cartilage degeneration of the patellofemoral joint using magnetic resonance imaging T2 mapping. Methods: This study included 37 patients (37 knees) who underwent OWHTO alone (OWHTO group) and 37 patients (37 knees) who underwent OWHTO with LRR (OWHTO + LRR group) with a correction angle of <10° for varus knee osteoarthritis. MRI was performed on all knees prior to and 6 months after surgery to assess the patellar cartilage in sagittal images for T2 mapping. Three regions of interest, (the medial facet, patellar ridge, and lateral facet), were established for the articular cartilage on the patellar side. The T2 values were subsequently quantified. Lower limb alignment, patellar height, patellar tilt angle, and lateral shift ratio were evaluated pre-and post-surgery. Results: Mean T2 values at 6 months post-surgery of the medial facet and patellar ridge of the OWHTO group showed a significant increase after surgery; no significant changes were observed in either region in the OWHTO + LRR group. In both groups, a significant decrease in patellar tilt angle was observed postoperatively; no change was noted in the lateral shift ratio or congruence angle. The change in patellar tilt angle was significantly lower in the OWHTO + LRR group than in the OWHTO group. Conclusions: LRR combined with OWHTO prevented patellofemoral joint cartilage degeneration after surgery in cases of varus knee osteoarthritis. Full article