Patellar Position Research Articles

Three-dimensional automated measurements of femoral angles for the preoperative planning in dogs with patellar luxation

ObjectivesTo report the surgical outcomes of treating patellar luxation (PL) in dogs with surgical planning based on three-dimensional (3D) automated measurement of femoral angles.Study designMulticenter retrospective study.MethodsForty-one dogs with PL underwent preoperative computed tomography (CT). Three-dimensional femur models were exported as stereolithographic files, and imported into computer-aided design (CAD) software where 3D measurements were performed. The anatomical laterodistal femoral (aLDFA), femoral neck (FNA), and femoral torsion (FTA) angles were recorded. Surgical records, complications, radiographic femoral postoperative alignment, preoperative and postoperative lameness evaluation, and patellar position were reviewed. The success of the surgical outcome was based on the presence of normal patellar tracking at the last clinical recheck.ResultsForty-seven limbs were included; 46% of the cases (22/47) were affected by grade 3 PL. Mean (±SD) 3D aLDFA, FNA, and FTA measurements were 101.4° (±3.6), 132.5° (±2.6), and 17.6° (±4.3) in dogs with medial patellar luxation (MPL) and 89.3° (±7.6), 134.8° (±2.9), 36.9° (±5.3) with lateral patellar luxation (LPL), respectively. Based on the 3D preoperative planning, corrective osteotomies were performed in 34 of 47 cases. The mean radiographic follow-up was 4.7 months. At the final follow-up, PL was successfully treated in 45 of 47 cases. Patella reluxated in five cases. In three of five cases, the 3D automated plan was not followed by the surgeon.DiscussionSurgical treatment of PL based on 3D femoral measurements successfully corrected PL in 45 of 47 cases (96%). This is the first study reporting the use of 3D automated femoral angle measurement in clinical cases affected by PL.

Changes in donor site after two variants of patellar tendon graft harvest

Background. The patellar tendon is often used as ACL graft. Identifying of factors that improve donor site healing may improve the outcomes.Aim. Study changes in the patellar tendon after two variants of graft harvest techniques and determine what features contribute to better donor site healing.Methods. The morphology of the patellar tendon was studied after two variants of graft harvest techniques with early rehab protocol. The retrospective group included 30 patients with no patellar tendon and bone defects closure. The prospective group included 30 patients with full-layer patellar tendon suture and bone defects closure. The Insall-Salvati ratio after surgery was measured on an X-ray in both groups. MRI study before surgery and 12 months after and CT 1 day and 6 months after surgery was performed in prospective group. The sizes of patellar tendon and conditions of bone defects were studied. Results. Patella position was physiological and did not differ between the groups (1.11 ± 0.13 - in group 1 and 1.12 ± 0.15 - in group 2, p = 0.955). In the prospective group after 12 months the patellar tendon length was shorter by 3.1% (-1.4 ± 2.4 mm, p = 0.003); the ligament width in the upper and middle thirds slightly increased (0.3±2.4 mm, p=0.502 and 0.5±2.1, p=0.205), and in the lower third it was 2.7% greater (0.7±1.7 mm, p=0.034); the ligament thickness increased by 55% (2.4±1.6 mm, p=0.001). All patients in group 1 had persistent bone and tendon defects. In group 2 the bone defects healed 6 months after, the ligament restored its shape and size, approaching the preoperative values 12 months after the surgery.Conclusions. Full-layer suture of the patellar tendon, autoplasty of bone defects and early mobilization ensure healing of bone defects and restoration of the integrity, shape and size of the ligament.

Neglected Patellar Tendon Rupture Reconstruction With Peroneus Longus Tendon Autograft and Modified Quadriceps Lengthening: A Case Report

Neglected patellar tendon reconstruction poses several challenges, including considerations for graft options, quadriceps lengthening, and postoperative extensor strength. There is no universal consensus on the optimal technique for neglected patellar tendon reconstruction. In this study, we report the patient with a neglected patellar tendon resulting from trauma occurring 1 year earlier. This patient has ambulatory disturbance, a high-riding patella, and notable limitations in knee range of motion. Our reconstruction procedure involves the use of the peroneus longus autograft, in conjunction with prolene mesh and modified quadriceps tendon lengthening. The results demonstrate an adequately restored patellar position, as evidenced by an Insall-Salvati ratio of 1.3. The patient exhibits a good functional outcome.

Lowering of the Patella — prevention and treatment of a rare complication during leg lengthening: a case report

Background. Changes in the level of the patella position are a well-known complication of knee replacement, reconstruction of the anterior cruciate ligament, high tibial osteotomy and consequences of injuries. However, this problem has not been disclosed in the literature in relation to distraction osteogenesis using the Ilizarov method. The aim of the study is to describe such a rare iatrogenic complication as patella baja during limb lengthening by the Ilizarov method using a clinical case as an example. Case description. In 2017, a 17-year-old teenager was injured in a head-on collision of cars at high speed. The patient was diagnosed with an open fracture of the left femur and fibula and tibia of the left leg. He was treated in another clinic using the Ilizarov apparatus for osteosynthesis of the femur, tibia and proximal osteotomy of the tibia to move the bone to fill the distal bone defect. At the end of the treatment, the patient had a moderate limitation of the knee flexion (180-80°). In 2018, the patient was admitted to our clinic due to osteomyelitis at the level of the consolidated fracture. A new resection of the osteomyelitis lesion and proximal osteotomy for bifocal osteogenesis were performed. During the treatment, limitation of knee flexion (180-120°) was developed and radiographic signs of low position of the patella were obtained. Given the progression of patella baja (the Caton-Deschamps index = 0.51), we were forced to return the patient to the operating room to restore the correct height of the patella. Conclusions. The presented clinical case emphasizes the need for a more thorough assessment of the patella height after surgical treatment on the proximal tibia using the Ilizarov method. It is also noted that it is important to conduct a control MRI, which allows for a more detailed study of the initial position of the anterior tibial tubercle. In our case, early detection of complications allowed us to achieve complete recovery without any consequences.

MRI analysis of the physiological patellofemoral joint morphology of adult knees.

The aim of the present study was to determine physiological reference values for the morphology of the patella and to analyse these parameters according to patella position in healthy knee joints. Healthy knee joints of 409 patients (mean age, 52.3years [± 16.8]) were analysed retrospectively on MRI images for Insall-Salvati index (ISI), sagittal patella thickness (PTS) and patella length (PLS) as well as axial patella thickness (PTA) and patella width (PWA). Differences between patellar diameters were analysed depending on ISI, side, age and gender. Mean PTS was 20.1 mm (± 2.4), PLS 44.0 mm (± 4.4), PTA 21.8 mm (± 2.4) and PWA 44.5 mm (± 4.7). Depending on the vertical patellar position (ISI), all patellar parameters (p < 0.01) showed significant differences between patients with a patella alta, norma and baja. In general, a smaller ISI showed higher measured values for the patellar parameters. There were no significant differences for the laterality. Only PTS showed a significant age difference (p = 0.031). All parameters were significantly larger in male compared to female knees (p < 0.001). Reference parameters for the patella morphology are reported. Concluding from the results, a relationship between vertical patellar position and patellar morphology seems to exist. This finding should be taken into account in diagnostics and therapy of patella disorders.

Tibial Tubercle Osteotomy With and Without Medial Patellofemoral Ligament Reconstruction in Adolescent Patients Leads to Decrease in Patellar Height and Patella Tendon Length.

Patellar height changes after tibial tubercle osteotomy (TTO) have not yet been described. We aimed to evaluate whether TTO ± medial patellofemoral ligament reconstruction (MPFL-R) influences patellar height and tendon length, hypothesizing that TTO would decrease patellar height and tendon length. A retrospective review was performed of skeletally mature adolescents (<18y) receiving primary anteromedialization or medialization TTO ± MPFL-R. Patients with at least 6 months of radiographic follow-up were included in the study. Pre and postoperative patellar heights were assessed on lateral, weight-bearing, and flexion (30 to 70 degrees) radiographs using the Blackburne-Peel Index (BPI), Caton-Deschamps Index (CDI), and Insall-Salvati Ratio (ISR). Subgroup analyses were performed to compare patellar height changes in patients with preoperative patella alta, norma, and baja, as well as between patients undergoing medialization and anteromedialization TTO. Data were analyzed for normality using a Shapiro-Wilk test, and paired-sample t tests were performed. Forty-nine knees were included (mean age: 15y; range: 12 to 17). A significant decrease in mean patellar height after TTO ± MPFL-R was observed across all measures: BPI (0.12, P = 0.000783), CDI (0.08, P = 0.01062), and ISR (0.15, P = 0.00000075). Patellar tendon length decreased by 2.26mm ( P = 0.001272). Subgroup analyses demonstrated a decrease in mean patellar height across all 3 measurements ( P < 0.001; BPI, CDI, and ISR) for patients with preoperative patella alta but not patella norma or baja. Additional subgroup analysis showed a patellar height decrease using BPI (0.15, P = 0.004583) and ISR (0.14, P = 0.0002806) for patients receiving medialization TTO but not anteromedialization. The anteromedialization cohort did not demonstrate patellar height change using BPI and CDI; ISR demonstrated a decrease (0.10, P = 0.00917). Mean patellar height and tendon length decreases after TTO ± MPFL-R in skeletally mature, adolescent patients. Subgroup analyses suggest these changes occur in patients with preoperative patella alta and/or patients who undergo medialization TTO. These data suggest that some distalization in patellar positioning may be achieved without formal distalization osteotomy.

Evaluation of the Tibial Plateau-Patella Angle (TPPA) in Dogs.

Estimating a dog's patellar position involves various methods, which categorize it as norma, alta (high), or baja (low). However, they require various calculations. We aimed to evaluate the clinical applicability of a new method, the tibial plateau-patella angle (TPPA). This could aid in planning patella luxation surgery, estimating the patella position after TPLO and various osteotomies. We conducted a two-step study: first, on 15 stifles without pathologies from nine canine cadavers, and second, using 100 patient X-rays from the archive. Three stifle angle positions (45 ± 5°, 90 ± 5°, and 135 ± 5°) and three weight groups (S, M, and L) were evaluated in the first part of this study. Based on these results, the second part of this study was conducted using 100 pathology-free radiographs at the optimal stifle angle (90 ± 5°) from the archive. All radiographs were measured by three observers with varying levels of experience. Our results indicate that the stifle angle significantly impacted the TPPA, whereby lower values were detected with higher stifle angles, which remained consistent within the weight groups. High inter- and intra-observer agreement was achieved. The physiological TPPA values ranged from 26.7° to 48.8°, remaining consistent within the various weight groups. Observer 3 in Group S exhibited a 20% (insignificant) deviation, possibly due to challenges in determining the caudal point of the tibial plateau. In contrast with humans, TPPA values in dogs are negatively correlated with stifle angles, independent of weight. Our reliable and reproducible protocol suggests the potential benefits of training on small-breed dogs stifles.

Effect of soft tissue tension around the knee joint on medio-lateral patellar position

Patellofemoral pain (PFP) is one of the most common sports injuries of the knee joint and has a high persistence and recurrence rate. Medio-lateral patellar position in the knee extension position during contraction is associated with PFP. However, soft tissue tension that most influences the medio-lateral patellar position in the knee extension position during contraction in vivo is unclear. We aimed to clarify the relationship between medio-lateral patellar position and soft tissue tension around the knee joint. Twelve patients with PFP and 20 healthy participants were included. Medio-lateral patellar position and tension of the rectus femoris, vastus lateralis (VL), vastus medialis, iliotibial band (ITB), lateral patellofemoral ligament, and medial patellofemoral ligament were measured during contraction and rest. The tensions of the VL and ITB during contraction and the medio-lateral patellar position at rest were significantly associated with medio-lateral patellar position during contraction (β = 0.449, 0.354, and 0.393, respectively). In addition, the tension of ITB was significantly associated with the medio-lateral patellar position at rest (β = 0.646). These relationships were not affected by the presence of PFP. These findings suggest that the patellar position during contraction became more lateral as the tension in the VL and ITB increased, regardless of the presence of PFP. These results may facilitate the prevention and treatment of PFP.

Incidence of patella baja and pseudopatella baja in aseptic revision total knee arthroplasty.

There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group's ROM. This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR. 55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001). After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making. III.

Osteotomy Correction Angle Cut-off Points Can Guide the Operation to Prevent a Significant Decrease in Patella Height.

Patients who undergo a biplanar ascending medial open-wedge high tibial osteotomy with an excessive correction angle might experience patella infera and even knee pain after surgery. The purpose of this study was to identify the cut-off points for the degree of knee varus correction of open-wedge high tibial osteotomy, which is related to the symptomatic patellar position change. This retrospective study included 124 patients (mean age 61.69 ± 6.28 years; 78 women, 46 men) with varying degrees of varus knee osteoarthritis. All patients had undergone standard biplanar medial open-wedge high tibial osteotomy. They were divided into nine groups according to the change in hip-knee-ankle angle. Plain radiographs and three-dimensional CT images were obtained preoperatively and 18 months postoperatively. Patellar height was assessed using the Caton-Deschamps index, the Insall-Salvati index, and the Blackburne-Peel index. The patellofemoral index and patellar tilt were used to evaluate the degree of horizontal displacement of the patella. The varus correction, medial-proximal tibial angles, joint line convergence angles, and hip-knee-ankle angles were also measured. The subjective score was evaluated using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). There were significant changes in patella indexes in each group after surgery, among which there was no significant difference in patellar height changes for Groups A to F (p > 0.05), which were significantly lower than those in Group G, H, and I (p < 0.001). The patellar tilt and patellofemoral index also followed the same trend. The improvement in WOMAC scores for Groups G, H, and I was also significantly less for Groups A to F (p < 0.001). The patellar height, patellar tilt, and patellofemoral index all changed significantly in parallel with increasing degrees of osteotomy correction. The cut-off points for correction angle are 12.5° to 13.4°. When the correction angle is larger than this range, the patellar position can be significantly affected. Postoperative patellofemoral joint pain may be related to the changes in patella position.

Association between patellofemoral osteoarthritis with demographic features and anatomical variants of the knee in non-traumatic patients

Background: Patellofemoral osteoarthritis (PFOA) is a common cause of knee discomfort and impairment, particularly among athletes. The development of PFOA has been associated with anatomical knee variations, such as trochlear dysplasia and patella alta. However, the relationship between these anatomical variants and the development of PFOA remains poorly understood. This study aimed to investigate the association between PFOA and knee anatomical variants in a cohort of patients. Methods: The study included 200 patients with PFOA and 200 healthy controls. In this study, we investigate the relationship of osteoarthritis with both anatomical variants and demographic characteristics. The participants underwent Magnetic resonance imaging (MRI) evaluation of the knee, and anatomical variants including trochlear dysplasia and patella alta were assessed. The severity of PFOA was also graded based on cartilage area and depth, as well as the bone marrow involvement and presence of osteophytes. Results: Statistically significant differences were observed between the two groups in terms of Tibial tuberosity-trochlear groove (TT-TG) distance, patella position, trochlear dysplasia, and Insall-Salvati ratio. The mean TT-TG distance, prevalence of alta patella position, and Insall-Salvati ratio were significantly higher in cases (P&lt;0.001 for all), and cases had a higher incidence of trochlear dysplasia (P&lt;0.001). There were no significant differences between cases and controls regarding patella baja. Conclusion: Anatomical knee variants, including the TT-TG distance, trochlear dysplasia, and Insall-Salvati ratio, are significant risk factors for PFOA progression. The results also indicate that higher BMI and older age are significantly associated with more measures of MRI Osteoarthritis Knee Score (MOAKS) than demographic information. Among anatomical variants, a higher TT-TG distance and an increased grade of trochlear dysplasia show a significant relationship with more measures of MOAKS. Understanding the relationship between these factors has important clinical and research implications and can help inform the development of new treatments.

Bidirectional Patellar Luxation in Small- or Miniature-Breed Dogs in Japan; Patient Characteristics and Radiographic Measures Compared with Medial Patellar Luxation.

Bidirectional patellar luxation (BPL) is a relatively rare form of patellar luxation, with limited information reported regarding breed predisposition and etiology. The purpose of this study was to describe the patient characteristics and radiographic measures of proximodistal patellar position associated with BPL in dogs in Japan, compared with dogs with medial patellar luxation (MPL). A retrospective medical record search of surgically corrected MPL and BPL dogs was performed, and breed, age, sex, body weight, and presence of the patella alta in the extended-stifle position were recorded. The ratio of the patellar ligament length to patella length (PLL/PL) and the ratio of the distance between the proximal pole of the patella and the femoral condyle to patella length (A/PL) were measured on stifle radiographs. A total of 35 dogs with BPL and 95 dogs with MPL were included. The BPL was most commonly present in Toy Poodles (odds ratio compared to MPL dogs: 7.05) in the present study. There were no significant differences in age, sex, or body weight between the BPL and MPL groups. Patella alta in the extended-stifle position was more common in the BPL group (23.4%) than in the MPL group (0.8%). However, there were no significant differences in PLL/PL or A/PL between the BPL and MPL groups. The study highlights BPL in different dog breeds in Japan, and suggests that the occurrence of BPL may be related to stifle extension. However, more research is needed to fully understand the etiology of BPL.

Analysis and Mechanism(s) of Hemophilia a Pain in Factor VIII Knockout Mice

Hemophilia A (HA) is characterized by spontaneous bleeding and pain. To understand mechanisms underlying HA pain, we developed models of chronic &amp; acute pain in FVIII knock-out (F8KO; B6;129S-F8tm1Kaz/J) male mice using innovative translatable measures to assess pain-related behaviors &amp; gait. We tested for: [i] mechanical hyperalgesia using von-Frey monofilaments; [ii] physical activity using weight-bearing with incapacitance meter and video recordings of free moving mice for locomotion (walking/running), grooming (licking/rubbing body) &amp; rearing (standing); and [iii] gait analysis during normal walking using in-house assembled MouseWalker with high-speed camera &amp; artificial intelligence (AI)-based algorithms. We observed significant increase in behavioral features of pain starting at ~8wks which continues to 20wks in F8KO Vs age matched B6 (p&amp;lt;0.05), including mechanical hyperalgesia, weight-bearing asymmetry, less time in locomotion, rearing &amp; grooming. Gait analysis of ~10wks F8KO showed lowered all-stance, increased body instability, single-swing &amp; posterior extreme position indices to compensate for body instability. This suggests that joint pain may interfere with weight-bearing &amp; locomotion in F8KO, consistent with joint pain, and affect daily activities such as walking in HA patients. To simulate bleeding-induced “ acute” pain, we gently inserted 30 G needle into sub patellar position of right hind leg of ~6wks old, anesthetized mice. F8KO showed significantly (p&amp;lt;0.05) reduced locomotion, rearing, grooming, %weight applied and increased mechanical sensitivity on injured limb at 4 days post-injury (4D PI) Vs uninjured (UI) F8KO lasting to 4wks PI for most of behavioral parameters suggesting that nociceptive inputs are induced at injury and pain persists after healing. We observed significant spatiotemporal gait alterations in F8KO PI Vs UI (p&amp;lt;0.05 for all features), including reduced stance duration, step length, swing speed and increased swing duration in the injured right hind limb (IRHL) indicative of avoidance of weight bearing on IRHL. To compensate, UI left hind limb (LHL) showed increased stance &amp; reduced swing duration on LHL &amp; left front limb (LFL). These data suggest that F8KO tends to spend shorter ground time on IRHL and longer airtime, compensated by UI LHL &amp; LFL. These observations are complementary to those of mice with sciatic nerve injury &amp; arthritis and patients with rheumatoid arthritis, ankylosing spondylitis, and gout. We observed significant (&amp;lt;0.05) alterations in interlimb coordination with decreased diagonal swing &amp; compensation with increased bound swing, the simultaneous motion of both FLs. A significant increase in all stance index could be compared to increased double support phase &amp; stance phase in patients with HA. F8KO 4D PI showed significant (p&amp;lt;0.05) increase in plasma serum amyloid P &amp; IL6 Vs UI F8KO &amp; injured B6 (IB6). Knee joint at 4D PI Vs UI F8KO &amp; IB6, showed expansion of synovial membrane with increased cellular infiltrate &amp; significant (p&amp;lt;0.05) increase in myeloperoxidase, neutrophil elastase +ve cells, degranulating mast cells, calcitonin gene related peptide (CGRP) and substance P (SP). H&amp;E and iron-stained sections of the knee joint ~8wks PI showed significant signs of hemarthropathy (p&amp;lt;0.05) Vs UI F8KO &amp; I B6. Interestingly, at ~14wks UI knee joint of F8KO showed significant stromal changes Vs UI B6 demonstrated by increased vasculature, iron stores &amp; mild synovial hyperplasia, indicative of subclinical bleeding that could trigger the transition to chronic pain with age. The underlying mechanisms involve inflammation, mast cell and neutrophil activation, and vascular changes, perhaps triggered by bleeding. Mast cell tryptase &amp; neutrophil elastase activate protease-activated receptor 2, which may cause nociceptor and endothelial activation, leading to vascular dysfunction and pain. SP and CGRP stimulate vascular permeability and arteriolar dilatation, respectively, and are involved in the generation and maintenance of pain. Thus, neuro-immune and neuro-vascular mechanisms underlie HA pain and may interfere with healing. We show features of pain, gait &amp; weight bearing changes in F8KO mice similar to those of HA patients. Sensory and gait tests used by us have the potential to develop objective measures of pain in HA. Gait changes in F8KO mice precede joint arthropathy, thus may be an early assessment tool in patients with HA.

Trochlear Ridge Prostheses for Reshaping Femoral Trochlear Ridges in Dogs with Patellar Luxation.

To describe the implant characteristics and surgical application of a custom-made trochlear ridge prosthesis (TRP) and to report clinical outcomes in dogs affected by patellar luxation treated with TRP. Dogs affected by patellar luxation underwent computed tomography. A specific canine bone anatomical replica, a cutting guide, and a TRP were designed and provided for surgery. Surgical records, clinical and radiographic reassessments, complications, pre- and postoperative lameness, type and degree of patellar luxation, and TRP and patellar position after surgery were reviewed. Clinical outcomes were defined as full, acceptable, or unacceptable function. The TRP was implanted in 60 femoral trochleae: 48 unilateral and 12 bilateral. Successful correction of patellar luxation was achieved in 59/60 cases. TRP was applied with other surgical techniques in 36/60 of the cases and as the only surgical procedure in 24/60 cases. Overall, three complications were observed: two minor and one major (patellar luxation recurrence). Neither implant loosening nor infection was observed. The mean radiographic follow-up was 3.8 months. At the time of the final follow-up, 57/60 cases were scored as fully functional. The TRP application either alone or in combination with other surgical techniques allowed for correction of patellar luxation and improvement in preoperative lameness with nominal complications. TRP could represent a potentially reliable alternative to trochleoplasty.

Can Anterior Knee Pain Be Explained by Patella Position After Infrapatellar Tibia Intramedullary Nailing?

The objective of this study is to investigate the postoperative position of the patella and its relationship with anterior knee pain in patients operated with infrapatellar reamed tibia intramedullary nailing (IMN). Patients who underwent tibia IMN between 2019 and 2022 and who had anterior knee pain in their postoperative follow-up at least two outpatient clinic controls with an interval of at least one month were examined. Patellar height indices (Insall-Salvati, Blackburne-Peel, Caton-Deschamps, and modified Insall-Salvati) and sagittal angulation (patella-patellar tendon angles) were measured on the lateral direct radiographs of the patients in semi-flexion. As a control group, measurements were made on the contralateral intact extremity radiographs of the same patients. There was no significant difference in patellar height indices between the fractured and intact sides in any of the patients (p = 0.588; p = 0.747; p = 0.446; p = 0.573, respectively). When the sagittal angulations were analyzed, a significant difference was found between the fractured and intact sides of the patients (p = 0.048), resulting in an approximate three-degree change. Patellar sagittal balance has been identified as one of the contributing factors to the development of anterior knee pain following reamed tibial IMN. Further biomechanical and comprehensive clinical studies are needed on this subject.

The Impact of Patellar Position on Mediolateral Joint Gap in Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty: A Prospective Study

BackgroundThis prospective study aimed to investigate the influence of patellar position (ie, eversion, lateralization, and reduction) on medial and lateral gap measurements during total knee arthroplasty (TKA) in both cruciate-retaining (CR) and posterior-stabilized (PS) TKA designs. MethodsThe present work analyzed 50 knees with primary osteoarthritis that underwent TKA between July and November 2019. Medial and lateral gaps were measured at different knee flexion angles (0°, 45°, 90°, and 120°) in 3 patellar positions after sequentially inserting CR type and PS type trial component in the same knee. ResultsIn CR TKA, medial gaps in patellar reduction showed significantly smaller gaps at 90° and 120° of knee flexion compared to those in eversion and lateralization (P < .001). Lateral gaps in patellar reduction were also significantly larger than those in eversion and lateralization (P < .001). The mediolateral gap difference in patellar reduction was significantly greater at all flexion angles compared to those in eversion and lateralization (P < .001). In PS TKA, similar patterns were observed for medial gaps, lateral gaps, and mediolateral gap differences (P < .001). ConclusionsThe ligament balancing with the patella everted or subluxed may lead to an overly tight medial gap and/or loose lateral gap in the knee with a closed arthrotomy, which has potential consequences for knee function in both CR and PS TKA designs. The results of this study highlight the importance of considering patellar position to ensure optimal soft-tissue balance and joint stability in TKA.

Maintenance of the joint line and posterior condylar offset are the most notable variables for successful outcomes of revision total knee arthroplasty.

Controversy regarding which variables should be prioritized for better outcomes in revision total knee arthroplasty (RTKA) exists. This study aimed to comprehensively analyze the variables affecting RTKA outcomes. We retrospectively identified 87 RTKAs in 82 patients who were performed between March 2014 and February 2020. Range of motion (ROM), including flexion contracture (FC) and further flexion (FF), was analyzed according to the covariates. The covariates included mode of failure, joint line position, anteroposterior (AP) position, rotational alignment of the femoral component, and patellofemoral alignment. The differences between the final follow-up values of each RTKA variable and those of the native knee were evaluated. The clinical outcomes were evaluated. No significant differences were observed between the joint line positions of the RTKA and native knees. The patellar and AP positions of the femoral component were restored to pre-TKA values. The femoral component had an external rotation of 2.78° compared with the native knee. In multivariable stepwise regression analysis, restoration of the adductor tubercle joint line and posterior condylar offset (PCO) were significant variables affecting ROM. Septic RTKA (33 knees) resulted in poor FF outcomes (p = 0.030) and Western Ontario and McMaster Universities Osteoarthritis Index stiffness (WOMAC S) scores (p < 0.001), compared with aseptic RTKA (54 knees). Restoration of the joint line position and PCO are crucial factors for improved ROM in RTKA. Joint line elevation in RTKA resulted in worse ROM than joint line lowering. In addition, RTKA due to septic failure had inferior ROM and WOMAC S scores compared with RTKA due to aseptic failure. Level III, cohort study.

Periarticular knee osteotomies for pre-arthritic deformities in the frontal plane : Indications and surgical techniques

Currently, periarticular knee joint osteotomies are an integral part of the treatment of early arthritic deformities in the knee joint. Analysis of the deformity is performed with astandardized full-leg standing x‑ray of both legs, as well as alateral x‑ray of the knee joint that includes 2/3 of the proximal tibial shaft. An MRI examination of the knee joint is obtained to assess the articular cartilage, the ligaments and menisci. Torsion angle measurements with the CT/MRT supplement the diagnostics if necessary. Knowledge of normal physiological values and their standard deviations of the mechanical leg axis and the joint angles around the knee is obligatory. The osteotomy is performed as close as possible to the femoral and/or tibial deformity. Postsurgical deformities including pathological patella position or asignificant difference in leg length must be prevented. Adescription of proximal tibia opening or closing wedge osteotomies based on the nomenclature of the joint angles by Paley is presented. The indications for the various osteotomy techniques in the coronary plane are discussed in detail.

Comparison of CT-measured angles of pelvic limbs without patellar luxation of six canine breeds.

Dogs with medial patellar luxation can be affected by pelvic limb deformities whose corrective osteotomies and associated biomechanical rebalancing might provide higher success rates than standard surgical procedures limited to the stifle joint. In bilaterally affected canine patients, comparison with the contralateral normal limb is impossible. Reference values are useful for orthopedic decision-making. Inconsistency of published reference values might depend on methodology or canine breed. We hypothesized that canine pelvic limb alignment is breed-specific. CT scans of 42 pelvic limbs of dog breeds predisposed for medial patellar luxation, with an orthotopic patellar position and stability were studied. Several angleswere measured with an open-source 3D Slicer plugin using vector calculations. The breeds were compared with a general linear model with a Bonferonni adjustment using SPSS. Chihuahuas, Pomeranians, Jack Russel Terriers, Pugs, French Bulldogs, Maltese were examined. In the order of the listed breeds, the angles were as follows: 28.3°±10.7°, 20.1°±2.9°, 35.4°±6.9°, 32.8°±3.0°, 19.0°±7.1°, 26.6°±5.3° for the antetorsion, 5.3°±1.8°, 2.8°±2.8°, 8°±4.4°, 3.8 °±3.1°, 4.7°±3.3°, 2.3°±3.3° for the femoral varus, of -5.5°±6.2°, 1.1°±4.1°, -5.2°±9.5°, 6.1°±8.0°, -0.1°±5.9°, -9.2°±4.7° for the tibial torsion, 2.0°±2.9°, 2.1°±2.7°, 6.4°±6.8°, 0.0°±5.7°, 3.0°±5.8°, 8.8°±8.6° for the tibial valgus, 1.2°±10.4°, 1.8°±3.4°, -1.7°±4.9°, -1.7°±9.4°, 5.1°±8.8°, -0.2°±8.6° for the femorotibial rotation and -3.4°±2.2°, 1.1°±4.1°, -2.8°±3.4°, -5.2°±4.0°, -2.1°±4.4°, -5.4°±3.7° for the tibiotalar rotation. There were significant differences between breeds in femoral torsion, femoral varus, and tibial torsion angles, but no significant differences in tibial valgus, femorotibial, and tibiotalar rotation angles. Our hypothesis is therefore partially correct. Our results are limited to small dogs prone to medial patellar luxation and might not be generalized. To establish robust reference values larger case numbers and more breeds should be evaluated. In conclusion, canine pelvic limb alignment reference values for small dogs with a predisposition for medial patellar luxation should be considered breed-specific.

Poster 291: Ultrasound-based patellar glide test: A new dynamic assessment of patellar instability

Objectives: Patellar instability can be difficult to assess due to the dynamic nature of this condition. While MRI and CT can demonstrate the morphology of the patellofemoral joint, the assessment of instability relies on dynamic testing. The patellar glide test is commonly utilized as a method of dynamic assessment on physical examination, yet precise quantification with this method remains difficult. Recently, cadaveric studies have demonstrated the utility of ultrasound in quantifying patellar translation. Therefore, our study aimed to apply the ultrasound-based patellar glide test to determine its utility in differentiating between knees with and without patellar instability in a clinical population. Methods: Patients with recurrent patellar instability were included in this study. Using a portable device, the ultrasound-based patellar glide test was performed with the knee in extension, and patellar position was visualized with and without a manual lateralizing force. The ultrasound probe was placed at the medial patellofemoral joint to visualize the relation of the medial patellar facet to the medial trochlea. Descriptive statistics were used to describe patellar position in the unloaded and loaded states, and patellar translation was calculated as the difference between the loaded and unloaded positions. Values were compared between symptomatic and asymptomatic knees. For each measurement of translation, receiver operating characteristic (ROC) curve analysis was performed. Youden’s J statistic was calculated to determine the optimal cutoff values to distinguish between asymptomatic vs symptomatic knees. Results: 50 knees from 25 patients (17F, 8M, mean age 26.9+/-9.4) were included in this study, of which 29 knees were unstable and 21 were stable and asymptomatic. When comparing symptomatic and asymptomatic knees, patellar position in the unloaded (4.6+/-2.8mm vs 3.8+/-2.3mm, p=0.277) and loaded states (1.1+/-3.24mm, 2.1+/-2.5mm, p=0.252) were not significantly different. Patellar translation was found to be significantly different between the symptomatic and asymptomatic states (3.5+/-2.2mm vs 1.7+/-1.5mm, p=0.002). ROC curve analysis demonstrated that patellar translation &gt;3mm detected the presence of patellar instability with AUC 0.88 (95% CI 0.77, 0.98). 3mm translation was found to identify patellar instability with sensitivity 43.4%, specificity 95.2%, PPV 90.9%, and NPV 60.6%. Conclusions: The ultrasound-based patellar glide test was found to differentiate between symptomatic and asymptomatic knees in patients with patellar instability with high accuracy. Given the increasing availability of portable ultrasound devices and the need for quantification of patellar laxity, further studies are recommended to evaluate the role of this method of assessment in the diagnosis and management of patellar instability.