Tibia Vara Research Articles

Difference in Rotational Alignment of the Tibial Component, as Determined by the Range-of-Motion Technique and Akagi's Line, is Influenced by Tibial Varus Deformity: A Cross-Sectional Study.

Anatomical landmarks and range-of-motion (ROM) techniques are commonly used to rotationally align the tibial component in total knee arthroplasty (TKA). This study investigated; 1) the difference in tibial rotational alignment between the ROM technique and Akagi's line, 2) the influence of preoperative deformity and intraoperative gaps on this difference, and 3) intraoperative tibial rotational kinematics associated with these 2 techniques. Patients who underwent cruciate-substituting (CS) TKA (Evolution, Microport Orthopedics) for knee osteoarthritis were enrolled. Intraoperatively, the rotational alignment of the tibial component was determined with the ROM technique and recorded. The difference from the value determined using Akagi's line was evaluated. Correlations among preoperative coronal deformity, postoperative coronal alignment, and intraoperative gaps between the femur and tibia were evaluated. Differences in knee kinematics (rotational movement of the tibia against the femur) between the 2 techniques were compared. This study included 34 knees from 34 patients. The rotational alignment of the tibial component using the ROM technique was 2.5±6.4° externally rotated in relation to that determined using Akagi's line (p=0.029), which was increased in knees with a smaller preoperative medial proximal tibial angle (r=0.45). Tibial rotational kinematics did not significantly differ between the 2 techniques. The ROM technique and Akagi's line yielded significantly different values for the rotational alignment of the tibial component. Orthopedic surgeons using Evolution (CS) should be reminded that in knees with proximal tibial varus deformity, the ROM technique will result in external rotation of the tibial component in relation to Akagi's line.

Surgical correction of pes varus deformity in dachshunds using three-dimensional-printed patient-specific guide system: nine tibiae in seven cases (2018-2022).

To describe the use of a three-dimensional-printed patient-specific guide system for the treatment of distal tibial varus deformity in Dachshunds and retrospectively report the clinical and radiographic outcome. Pes varus deformity in nine limbs of seven dachshunds was treated with corrective osteotomy using a three-dimensional-printed patient-specific guide system. Data from computed tomography were processed to obtain virtual 3D-models of the tibias, which were used for computer-aided design-based surgical planning, three-dimensional-printed patient-specific guide system design and evaluation of planned versus achieved tibial correction. Clinical outcomes were evaluated by lameness score and post-operative owner-reported questionnaire at a minimum of 15 months. The gait abnormality resolved in all limbs. The osteotomy healed uneventfully in eight tibiae. Implant failure occurred in one tibia but was successfully revised. There was good correlation between planned and achieved deformity correction, with mean translational error <1 mm in all planes, and mean angulation correction error <2° in all planes. A 3D-printed patient-specific osteotomy and reduction guide system facilitates the accurate correction of tibial pes varus deformity with very good clinical outcomes. Opening osteotomy, stabilised with orthogonal locking plates and without the application of bone graft led to satisfactory bone healing in all cases.

Medial Tibial Condylar Valgus Osteotomy improve clinical outcomes and effectively corrects significant Tibial varus deformities without compromising joint line obliquity or patellar heigh

BackgroundTibial condylar valgus osteotomy (TCVO), or Chiba osteotomy, is a recognized procedure for treating advanced knee osteoarthritis in middle-aged individuals. Although its effectiveness is established, limited literature exists on its outcomes for specific conditions such as post-traumatic deformities, Blount disease (BD), and Pagoda-like proximal tibia varus deformities. HypothesisWe hypothesized that TCVO could improve both clinical and radiographic outcomes in patients with severe varus deformities, correcting lower-limb variances while preserving joint line obliquity (JLO) and patellar height in substantial varus deformities. Patients and methodsThis study included 33 patients who underwent TCVO, with etiologies including post-traumatic (26 patients, 78.8%), Blount disease (4 patients, 12.1%), and Pagoda deformities (3 patients, 9.1%). The average age was 32.5 years (standard deviation = 12.8 years). Techniques for deformity correction varied, including Patient Specific Instrumentation (PSI) for 10 patients (30.3%) and locking plate fixation for 13 patients (39.4%). We assessed several radiological parameters such as hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), Caton-Deschamps index (CDI), and proximal posterior tibial angle (PPTA). Patient-reported outcomes, including the Knee injury and Osteoarthritis Outcome Score (KOOS) and simple knee value (SKV), were recorded both pre-operatively and two years post-operatively. ResultsStatistically significant improvements were observed in clinical scores and alignment changes two years post-operatively, including increases in HKA (from 166.1 to 178.4, p < .0001) and MPTA (from 72.4 to 85.1, p < .0001), and a decrease in JLO (from 9.8 to 3.2, p < .0001). No significant changes were noted in JLCA, PPTA, and CDI, with the patellar height remaining stable post-operatively. The achieved corrections closely matched the pre-operative plans. ConclusionTCVO offers significant improvements in radiological and clinical parameters for patients with substantial tibial varus deformities, effectively maintaining JLO and patellar height. Optimal outcomes from TCVO are dependent on careful patient selection and precise execution of surgical techniques. Level of evidenceIII.

Modified pendulum osteotomy to correct severe tibial varus deformity

Correction of asevere tibial varus deformity near the knee joint with only aslight influence on leg length and patella height. Medial osteoarthritis and/or cartilage damage with asevere varus deformity > 10° with amedial proximal tibial angle (MPTA) < 80°. Femoral varus deformity with lateral distal femoral angle > 91°, severe lateral cartilage damage, lateral osteoarthritis, lateral meniscus loss. Skin incision of approx. 8-10 cm between the tibial tuberosity and the head of the fibula. Exploration of the peroneal nerve. Detachment of the extensors. Insertion of an obliquely ascending guidewire ending approximately 10 mm below the medial articular surface. Insertion of asecond guidewire. This aims at the middle of the first wire (hemi wedge). Check the wire position under fluoroscopy. Osteotomy with an oscillating saw under cooling. Removal of the wedge and closure of the osteotomy. Percutaneous needling of the medial collateral ligament with acannula to carefully lengthen the ligament. Check the correction result with ametal rod. Osteosynthesis with lateral angle-stable plate. Partial weight-bearing with 10 kg for 6weeks postoperatively, free range of motion. Reports from the literature show that good clinical results can be achieved with this procedure for severe tibial varus deformities. Postoperative leg length discrepancies are less common with this procedure than with laterally closing osteotomy.

Focal Fibrocartilaginous Dysplasia and Growth Arrest

Case: A pediatric patient with focal fibrocartilaginous dysplasia (FFCD) developed angular deformity and growth arrest despite standard guided growth management. The patient underwent implant-mediated guided growth for proximal tibia varus deformity which recurred; subsequently, a physeal bar of the medial proximal tibia was diagnosed, which progressed to physeal arrest. Conclusion: Treatment options for FFCD-associated angular deformity include observation and guided growth. This case highlights the risk of complete physeal arrest in FFCD.

Femoral and tibial phenotypes of varus alignment in a Southeast Asian arthritic population: a descriptive study.

Knowledge of femoral and tibial morphology is important for patient-specific surgery in both joint reconstruction and preservation procedures. Studies evaluating morphological variance in femoral and tibial alignments in Asian populations are scarce. This is the first descriptive study evaluating the femoral and tibial phenotypes of varus alignment in a Southeast Asian population. Long-leg coronal standing radiographs of 2021 limbs were obtained, and the hip-knee-ankle angle, mechanical lateral distal femoral angle, medial proximal tibial angle and joint line convergence angle were measured. Joint line obliquity was calculated, and the knees were classified according to the Coronal Plane Alignment of Knee (CPAK) classification. Descriptive analyses on alignment parameters and demographic data (age, gender, ethnicity and body mass index [BMI]) were performed and entered into a linear regression model. The highest frequency of limb alignment in the population was found to be CPAK type I (52.71%, n = 1003). Tibial varus was the largest contributor of varus malignment. Of the varus knees (n = 1247), varus deformity was found solely in the tibia (68.60%), solely in the femur (2.07%) and was contributed by both the femur and the tibia (4.97%). In the linear regression model, BMI was found to be a strong determinant for femoral varus (P = 0.004) and joint line incongruence (P < 0.001). The findings of this study will be important to surgeons during planning for joint preservation procedures (such as corrective osteotomies) and joint arthroplasties to restore alignment.

Establishing a Reference Database for Select Clinical Measures in National Basketball Association Players.

Musculoskeletal injuries are prevalent in the NBA and are associated with a significant number of games missed. There is a lack of reference data for clinical measures in NBA players, making it difficult for sports medicine professionals to set goals and develop programs. Values for clinical measures in NBA players will differ from those of the general population but will not differ between dominant (D) and nondominant (ND) limbs. Descriptive laboratory study. Level 3. Clinical measures were taken on 325 players invited to NBA training camp (2008-2022). Measures included range of motion for great toe extension, hip rotation, weightbearing ankle dorsiflexion, flexibility, arch height (AH) indices, and tibial varum. Clinical values for NBA players differ from reference norms of the general population. Results for NBA players include great toe extension (D, 40.4°; ND, 39.3°), 90/90 hamstring (D, 41.5°; ND, 40.9°), hip internal rotation (D, 29.0°; ND, 28.8°), hip external rotation (D, 29.7°; ND, 30.9°), total hip rotation (D, 60.2°; ND, 60.4°), Ely (D, 109.9°; ND, 108.8°), AH difference (D, 0.5 mm; ND, 0.5 mm), AH index (D, 0.310; ND, 0.307), arch stiffness (D, 0.024; ND, 0.024), arch rigidity (D, 0.924; ND, 0.925), tibial varum (D, 4.6°; ND, 4.5°), and weightbearing ankle dorsiflexion (D, 35.4°; ND, 35.6°). Descriptive statistics are presented; 2-tailed paired t tests show that, whereas most measures demonstrated differences between sides, the results were not statistically significant. Clinical measures of NBA players differ from those reported for the general population and athletes of other sports although there were no statistically significant differences between D and ND limbs. Establishing a reference database may help clinicians develop more sensitive and more effective preseason and return-to-play screening processes, aiding the management of player orthopaedic care and reducing injury risk.

Chiba osteotomy (Tibial condylar valgus osteotomy) for a large tibial varus deformity: Technical note

Chiba osteotomy is an effective technique for advanced knee osteoarthritis (KOA). The principle of the osteotomy is to correct both varus deformity and intra-articular joint congruity through an L-shaped osteotomy from the medial tibial condyle to the lateral intercondylar eminence. Previous studies have demonstrated that Chiba osteotomy is an effective method for alignment correction surgery for severe knee osteoarthritis. However, these reports slightly differ from the original concept of Chiba osteotomy. This report describes the pre-operative planning and surgical technique of Chiba osteotomy for patients with large tibial varus deformity, focusing on the management of early knee osteoarthritis following conditions such as post-traumatic Blount disease and “Pagoda” like proximal tibia varus deformities, as originally described. Level of evidenceIV

A Biomechanical Comparison Study of Plate-Nail and Dual-Plate Fixation in AO/OTA 41-C2 Tibial Plateau Fractures.

This study's purpose was to evaluate the biomechanical performance of plate-nail and dual-plate fixation for the treatment of AO/OTA 41-C2 tibial plateau fractures. Twenty synthetic tibias were selected and randomly divided into a plate-nail group (n = 10) and a dual-plate group (n = 10). After the artificial tibias were osteotomized to simulate AO/OTA 41-C2 tibial plateau fractures in both groups, the plate-nail and the dual-plate methods, respectively, were used for fixation, and then axial compression loading, three-point bending, torsion, and axial failure tests were carried out. The data of each group were recorded and statistically analyzed. In the axial compression test, the average stiffness of the plate-nail group was higher than that of the dual-plate group (p < 0.05). The displacement generated in the plate-nail group was significantly smaller than that in the dual-plate group (p < 0.05). In the resisting varus test, the stress of the plate-nail group was significantly higher than that of the dual-plate group (p < 0.05). In the resisting valgus test, the stress of the plate-nail group was slightly higher than that of the dual-plate group, but the difference was not statistically significant (p > 0.05). In the static torsion test, the load applied to the plate-nail group was smaller than that of the dual-plate group when rotated to 5° (p < 0.05). In the axial compression failure test, the average ultimate load of the plate-nail group was significantly higher than that of the dual-plate group (p < 0.05). The treatment of AO/OTA 41-C2 tibial plateau fractures with plate-nail fixation is superior to that with dual-plate fixation in resisting axial stress and preventing tibial varus deformity, while dual-plate fixation has better resisting torsional ability.

The effect of osteotomy depth and hinge axis orientation on biplanar surgical accuracy in medial opening-wedge high tibial osteotomy-a deeper understanding by 3D simulations.

Not all surgical osteotomy steps have been properly investigated for their potential impact on surgical accuracy. The main study objective was to investigate the osteotomy parameters that have respectively major and minor impact on coronal and sagittal bony accuracy in medial opening-wedge high tibial osteotomy (MOWHTO). Three tibias from an existing 3D MOWHTO osteotomy database were chronologically selected based on segmentation quality, tibial plateau size and the presence of tibial varus. The study consisted of three parts: (I) translating the hinge axis in the coronal plane and switching the osteotomy starting point (30-40 mm) and depth, (II) the hinge axis was rotated stepwise by 10° to perform five simulations, (III) the hinge axis was rotated in the axial plane stepwise by 10° towards anterolateral to perform four simulations (0°, +10°, +20°, +30°). The medial proximal tibial angle (MPTA) and lateral tibial slope were the primary outcomes. Simulations were performed with 5, 10 and 15 mm gap distraction. In the coronal plane, maximum difference in osteotomy depth was 10 mm which represented an MPTA difference of 0.8°-1.1° in 10 mm gap distraction and 1.2°-2.0° in 15 mm gap distraction. Tibial slope remained unchanged. Rotating the hinge axis in the sagittal plane delivered minor changes on both MPTA (<0.5°) and tibial slope (<1.5°) at 10 mm gap distraction. Per 10° of axial rotation of the hinge axis towards anterolateral, the tibial slope increased by 1.0°-1.3° in 10 mm gap distraction while the MPTA remains nearly unchanged. The study showed that the medio-lateral osteotomy length is the main parameter for obtaining bony accuracy in the coronal plane and maintaining a strict perpendicular axial hinge axis position is crucial in preserving the native tibial slope. Correct axial alignment of the hinge axis can be obtained by creating an equal osteotomy depth of the anterior and posterior tibial cortices in the lateral metaphyseal area.

Altered dynamic joint space in the lateral condyle compartment following medial unicompartmental knee arthroplasty

PurposeThe progression of osteoarthritis in lateral compartment has been identified as a primary complication in medial unicompartmental knee arthroplasty (UKA) revisions, irrespective of whether employing fixed bearing (FB) or mobile bearing (MB) designs. Compared to the previous contact point analyses, the tibiofemoral contacts during knee movements are comprehended by a more comprehensive understanding of joint spaces. This study aims to dynamically map the joint spaces in the lateral compartment during the single-leg lunge following FB and MB UKA procedures, and compare them with the respective contralateral native knees. It is hypothesized that the significant change in joint space for post-UKA compared to their native knees. MethodsTwelve patients with unilateral medial FB UKA and eleven patients with unilateral medial MB UKA were included and underwent computed tomography scans. The exclusion criteria included anterior cruciate ligament deficiency, postoperative knee pain, any postoperative complications, and musculoskeletal illnesses. A dual fluoroscopic imaging system was utilized to capture the single-leg lunge, and 2D-to-3D registration facilitated the visualization of knee motion. According to the knee motions, joint spaces on tibial and femoral surfaces in the lateral compartments of native, FB, and MB UKA knees were calculated and mapped. ResultsIn comparison to the native knees, FB UKA knees exhibited significant increases in medial, lateral, central, and posterior joint spaces in the lateral compartment (p < 0.05), while MB UKA knees showed significant increases only in central and posterior joint spaces (p < 0.05). Moreover, FB UKA demonstrated greater increases in medial, central, and posterior joint spaces compared to MB UKA. Tibial varus and valgus during lunges, as well as the Oxford Knee Score (OKS) and Hip-Knee-Ankle angle (HKA), correlated with joint spaces. ConclusionsDynamic joint space analysis provided a more comprehensive insight into contact dynamics. FB UKA led to an enlargement of joint spaces, whereas MB UKA resulted in joint spaces closer to native knees. These findings contribute to understanding potential postoperative complication in UKAs.

Opening-Wedge High Tibial Osteotomy with a Cancellous Strut Bone Allograft Is Inadequate for Achieving Satisfactory and Lasting Correction in Neglected Infantile Tibia Vara: Results from a Cohort of 29 Patients.

Background: Infantile tibia vara (ITV) is a rare proximal tibia deformity in infancy, leading to progressive knee varus. High tibial osteotomy is commonly practiced but has high recurrence rates. This study analyzed factors affecting treatment failure and recurrence in children undergoing opening-wedge high tibial osteotomy (OWHTO) for ITV. Methods: We retrospectively studied children with ITV who had OWHTO with a press-fit cancellous bone allograft between 2000 and 2020, with ≥2-year follow-up. Outcomes included recurrence (knee varus with tibiofemoral angle > 10°), complications, and reintervention. Results: We analyzed 39 knees in 29 patients (mean age: 4.8 ± 1.9 years; median follow-up: 7.4 years). Recurrence occurred in 22 cases (56%). Age at surgery significantly influenced recurrence, with rates of 16% before age 5 versus 95% later (hazard ratio: 12.0, p = 0.001). Langenskiöld stage also affected recurrence (β-coefficient: 2.7, 95% C.I. 1.0-4.5, p = 0.002; pseudo-R-squared: 0.50, p = 0.001), with recurrence in all stage IV or higher cases. Conclusions: Early diagnosis and treatment before age 5, ideally with Langenskiöld stage III or lower, are crucial for stable correction with OWHTO alone. Late, high-grade ITV may require combined, acute or gradual, and/or staged correction. Further evidence is needed for optimal management.

Ischaemic chondronecrosis as a novel causative factor in the aetiopathogenesis of infantile Blount’s disease

Infantile Blount’s disease primarily affects toddlers, leading to tibia vara with or without growth arrest. While the disease’s association with abnormal compressive forces on the proximal tibial physis is widely accepted, its precise aetiopathology remains elusive. This hypothesis suggests that ischaemic chondronecrosis serves as a previously unaddressed cause of Blount’s disease. Notably, it is also the foremost theory to offer a comprehensive explanation for the specificity of involvement of the posteromedial tibial epiphysis, addressing a crucial aspect that was overlooked in prior research. The theory of pressure-induced ischaemic chondronecrosis is supported by a compelling body of radiological and histological evidence. Experimental studies on femoral heads in animals highlight the susceptibility to ischaemic injury in the absence of an ossific nucleus. The proposed mechanism could explain the delayed ossification observed in the proximal medial tibial epiphysis in Blount’s disease. Comparisons with Perthes’ disease reveal striking parallels in radiographic and histological features, pointing toward a shared aetiology of vascular insult. Despite both conditions progressing through similar stages, the distinction lies in Perthes’ being characterised by osteochondral necrosis, while Blount’s results from chondronecrosis. The potential applications of this hypothesis extend to early detection and prevention, emphasising the avoidance of compression on the medial tibial epiphysis. The study suggests a reevaluation of brace therapy and exploration of the role of serial valgus casting, especially in the early stages of insult and limited to walking time, as a preventive measure against ischaemic chondronecrosis and its complications.In conclusion, this hypothesis sheds light on a novel mechanism of Blount’s disease. Further research is warranted to validate and refine this proposition, offering promising avenues for addressing a century-long enigma in its aetiology.

Osteotomies for genu varum: Should we always correct at the tibia? A multicenter analysis of practices in France

IntroductionTibial correction is often performed during a valgus-producing osteotomy for genu varum. However, overcorrection and the creation of a joint line obliquity (JLO) have been associated with unfavorable functional outcomes after high tibial osteotomy (HTO). The aims of this study were to analyze: 1) the corrections obtained after HTO; 2) the rationale behind the indication per the European Society for Sports Traumatology Surgery and Arthroscopy (ESSKA) recommendations; and 3) the correlation between the postoperative corrections obtained and functional outcomes. HypothesisA significant number of patients who underwent an isolated HTO did not present an “ideal” theoretical indication based on the preoperative angles and correction targets to be performed. Materials and methodsThis multicenter study included 289 isolated HTOs. Demographic and morphometric data were anonymized and compiled in a database. Preoperative radiographic parameters were compared with the ESSKA consensus recommendations on osteotomies for genu varum. The consensus defined the “ideal” indication for performing an HTO as medial tibiofemoral compartment pain with significant tibial varus deformity (medial proximal tibial angle [MPTA]<85°), no significant femoral varus deformity (lateral distal femoral angle [LDFA]<90°), an expected postoperative obliquity of less than 5°, and a correction resulting in moderate tibial valgus (postoperative MPTA<94°). The incidence of patients with an “ideal” theoretical indication for isolated HTO and those with a theoretical indication not perfectly justified by the radiographic data and preoperative planning were recorded. ResultsUnder the ESSKA consensus criteria, 25.3% (n=73) of isolated HTOs, 15.6% (n=45) of isolated femoral osteotomies, 9.3% (n=27) of double-level osteotomies, and 49.9% (n=144) of cases where no osteotomy was performed due to the lack of significant extra-articular tibial and/or femoral deformity were deemed justified. The presence of a preoperative femoral deformity and the absence of an “ideal” indication for HTO did not affect the postoperative Tegner Activity Scale or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (p>0.05). A high preoperative hip-knee-ankle (HKA) angle and MPTA, which indicated less varus, were associated with a greater risk of there being no “ideal” theoretical indication for an HTO (coefficient of determination [R2]=0.19 and R2=1, respectively; p<0.001). ConclusionThis study showed that isolated HTOs in current practice were not justified in a significant number of patients, even though they could lead to tibial overcorrection and excessive JLO. This did not impact the functional results of this series, but it might complicate the performance of a secondary knee arthroplasty. Nevertheless, some young patients in this series underwent a salvage osteotomy outside the “ideal” indications of the European recommendations. Level of evidenceIV; case series.

Enhancing robotic precision in medial UKA: Image-based robot-assisted system had higher accuracy in implant positioning than imageless robot-assisted system across 292 knees.

The objective of this study was to compare the degree of accuracy in implant positioning and limb alignment offered by two robot-assisted (RA) systems: an image-based robot-assisted (IBRA) versus an imageless robot-assisted (ILRA) system for the treatment of medial knee osteoarthritis with unicompartmental knee arthroplasty (UKA). This retrospective radiographic study included medial UKAs performed between 2011 and 2023. Radiographic measurements taken preoperatively and at 1-year postoperative control visit focusing on hip-knee-ankle angle (HKA), posterior tibial slope (PTS), tibial component coronal alignment relative to Cartier's angle and restoration of proper joint line (JL) height were analyzed. Outliers for postoperative measurements were defined as follows: HKA <175° or >180°, PTS <2° or >8°, >3° or <-3° alterations in Cartier's angle and ±2 mm changes in the height of the joint line. The final sample consisted of 292 medial UKAs: 95 (32.5%) with an IBRA system and 197 (67.5%) with an ILRA system. Implant positioning and limb alignment were more accurate in the group of patients treated with IBRA, HKA (77.9% vs. 67.5%, p = 0.07), PTS (93.7% vs. 82.7%, p = 0.01), restoration of tibial varus relative to Cartier's angle (87.4% vs. 65%, p < 0.001) and restoration of JL height (81.1% vs. 69.5%, p = 0.04). Medial UKA surgery using an IBRA system was associated with a higher degree of accuracy in implant positioning and postoperative limb alignment as compared to an ILRA system. This is a valuable contribution to help communicate the advantages of using this surgical technique and improve its reproducibility. Level III, Retrospective cohort study.

A Child with Severe Bilateral Tibia Vara: Treatment with Computer-Assisted Gradual Correction Utilizing Hexapod External Fixator

A 7-year-old obese boy presented to the Paediatric Orthopaedic clinic with a complaint of worsening bilateral knee bowing. He was initially seen for the same problem in another hospital at the age of 3. The bowing of the leg was associated with pain over the lateral aspect of both knees. He was able to walk but unable to run or participate in sports due to the deformity and knee pain. On examination, the child had a waddling gait and lateral thrust due to severe bilateral genu varus. The range of motion of bilateral knee joints was 0 to 110 degrees. The knee intercondylar distance was markedly increased and there was bilateral tibial torsion. No limb length discrepancy and neurovascular examination was normal. The radiograph revealed features of infantile tibia vara (Blount disease). Bilateral proximal tibia temporary hemiepiphysiodesis was attempted but no correction of the deformity was achieved due to implant failure. His parents were then counseled to let him undergo gradual deformity correction surgery using a ring external fixator (hexapod system). The bilateral varus deformity was corrected after 4 months, and the patient was able to walk normally.

3D Slicer open-source software plug-in for vector-based angle calculation of canine hind limb alignment in computed tomographic images.

Severe and complex angular limb deformities in dogs require accurate morphological assessment using diagnostic imaging to achieve successful orthopedic surgery. Computed tomography (CT) is commonly used to overcome projection errors in two-dimensional angular measurements of dog hindlimb alignment. Three-dimensional volume rendering (VR) techniques permit virtual positioning and variable projection, but the final CT-image that defines the projection plane for angular measurements remains two-dimensional. We wanted to develop a true three-dimensional open-source technique to measure the alignments of the hind limbs of dogs in CT scanners. We developed an open-source 3D Slicer plug-in, to perform angular measurements using vector calculations in three-dimensional space. In 113 CT-scans of canine pelvic limbs, femoral torsion, femoral varus, femorotibial rotation, tibial torsion, tibial varus and tibiotalar rotation angles were calculated and compared to an already validated technique using VoXim®. Reference points were identified and measurements were possible in the 113 acquisitions. The greatest difference between the two techniques was 1.4° at only one tibial torsion angle. Mean values for all Bland-Altman plots did not show significant differences and were less than 0.07° for all comparisons. Based on these results we considered angular measurements of canine hind limb alignment in CT scans using the 3D Slicer extension program sufficiently accurate for clinical orthopedic and surgical purposes in veterinary medicine. With our open-source 3D Slicer extension software, we provide a free accessible tool for veterinary orthopedic surgeons and thus we hope to improve angular measurements in CT-scans of canine hind limb deformities through true three-dimensionality.

Coronal Knee Alignment and Tibial Rotation in Total Knee Arthroplasty: A Prospective Cohort Study of Patients with End-Stage Osteoarthritis.

Several studies have found a relationship between the rotational anatomy of the distal femur and the overall coronal lower limb alignment in knees with osteoarthritis (OA). Less is known about the rotation of the proximal tibia, especially in the context of total knee arthroplasty (TKA), where one of the goals of the surgery is to achieve the appropriate component-to-component rotation. The aim of this study was to investigate the relationship between the coronal alignment of the lower extremity and the relative proximal tibial rotation. A prospective cohort study of patients with an end-stage OA scheduled for TKA was conducted. All patients underwent a computed tomography (CT) scan and a standing X-ray of both lower limbs. A relative femorotibial rotation was measured separately for mechanical and kinematic alignment. A statistically significant correlation was found between the tibial varus and the external tibial rotation (p < 0.001). Out of 14 knees with high tibial varus (>5°), 13 (93%) and 7 (50%) knees had >10° of femorotibial rotation for the mechanical and kinematic alignment landmarks, respectively. In order to keep the component-to-component rotation within the 10° margin, more internal rotation of the tibial component is required in knees with higher tibial varus.

Single-center experience with Knee+™ augmented reality navigation system in primary total knee arthroplasty.

Computer-assisted systems obtained an increased interest in orthopaedic surgery over the last years, as they enhance precision compared to conventional hardware. The expansion of computer assistance is evolving with the employment of augmented reality. Yet, the accuracy of augmented reality navigation systems has not been determined. To examine the accuracy of component alignment and restoration of the affected limb's mechanical axis in primary total knee arthroplasty (TKA), utilizing an augmented reality navigation system and to assess whether such systems are conspicuously fruitful for an accomplished knee surgeon. From May 2021 to December 2021, 30 patients, 25 women and five men, underwent a primary unilateral TKA. Revision cases were excluded. A preoperative radiographic procedure was performed to evaluate the limb's axial alignment. All patients were operated on by the same team, without a tourniquet, utilizing three distinct prostheses with the assistance of the Knee+™ augmented reality navigation system in every operation. Postoperatively, the same radiographic exam protocol was executed to evaluate the implants' position, orientation and coronal plane alignment. We recorded measurements in 3 stages regarding femoral varus and flexion, tibial varus and posterior slope. Firstly, the expected values from the Augmented Reality system were documented. Then we calculated the same values after each cut and finally, the same measurements were recorded radiologically after the operations. Concerning statistical analysis, Lin's concordance correlation coefficient was estimated, while Wilcoxon Signed Rank Test was performed when needed. A statistically significant difference was observed regarding mean expected values and radiographic measurements for femoral flexion measurements only (Z score = 2.67, P value = 0.01). Nonetheless, this difference was statistically significantly lower than 1 degree (Z score = -4.21, P value < 0.01). In terms of discrepancies in the calculations of expected values and controlled measurements, a statistically significant difference between tibial varus values was detected (Z score = -2.33, P value = 0.02), which was also statistically significantly lower than 1 degree (Z score = -4.99, P value < 0.01). The results indicate satisfactory postoperative coronal alignment without outliers across all three different implants utilized. Augmented reality navigation systems can bolster orthopaedic surgeons' accuracy in achieving precise axial alignment. However, further research is required to further evaluate their efficacy and potential.

No clinical outcome difference between varus phenotypes after medial opening-wedge high tibial osteotomy at 2 years follow-up.

Clinical studies regarding medial open-wedge high tibial osteotomy (MOWHTO) often analyse a large group of mechanical varus knees rather than differentiating for its primary varus-inducing component. This study aims to compare the radiological and clinical outcomes of the most prevalent varus malalignment phenotypes using the coronal plane alignment of the knee (CPAK) classification. MOWHTO cases with minimal 2-year clinical follow-up were retrospectively selected from a knee osteotomy database (2016-2020). Based on the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA), subjects were allocated to the correct CPAK phenotype pre- and postoperatively. Clinical outcomes were the numeric rating scale (NRS), the knee injury and osteoarthritis outcome score (KOOS) and the therapeutic response rate (TRR) at 2-year follow-up. Inter-observer correlation coefficient (ICC) and unpaired student t test were performed for cross-phenotype comparison. One hundred thirty-five (135) subjects were found eligible (53.0 years old ±9.6 [19-77], 72% male, 53% left-sided). The most prevalent preoperative phenotype was CPAK 1 (n = 70 (52%)) and the postoperative phenotype was CPAK 6 (n = 66 (49%)). All CPAK phenotypes improved significantly relative to baseline but cross-phenotype comparison yielded no significant differences in clinical outcome. The TRR at 2 years was 67% for CPAK 1, 69% for CPAK 2and 87% for CPAK 4. The TRR for CPAK 6 was 64% compared with 80% for CPAK 9, which was not significantly different. At 2-yearfollow-up, no clinically significant differences are observed between different CPAK phenotypes. Accurate MOWHTO corrections provide significant clinical improvement even in the femoral-driven varus knee and the constitutional varus knee dominated by intra-articular wear. The clinical indication for MOWHTO performance should not be reduced to the medial arthritic varus knee with underlying tibial varus alone. Level IV, retrospective comparative study.