Modulation of early osteoarthritis by tibiofemoral re-alignment in sheep.

OBJECTIVE: To investigate whether tibiofemoral alignment influences early knee osteoarthritis (OA). We hypothesized that varus overload exacerbates early degenerative osteochondral changes, and that valgus underload diminishes early OA. METHOD: Normal, over- and underload were induced by altering alignment via high tibial osteotomy in adult sheep (n = 8 each). Simultaneously, OA was induced by partial medial anterior meniscectomy. At 6 weeks postoperatively, OA was examined in five individual subregions of the medial tibial plateau using Kellgren-Lawrence grading, quantification of macroscopic OA, semiquantitative histopathological OA and immunohistochemical type-II collagen, ADAMTS-5, and MMP-13 scoring, biochemical determination of DNA and proteoglycan contents, and micro-computed tomographic evaluation of the subchondral bone. RESULTS: Multivariate analyses revealed that OA cartilaginous changes had a temporal priority over subchondral bone changes. Underload inhibited early cartilage degeneration in a characteristic topographic pattern (P ≥ 0.0983 vs. normal), in particular below the meniscal damage, avoided alterations of the subarticular spongiosa (P ≥ 0.162 vs. normal), and prevented the disturbance of otherwise normal osteochondral correlations. Overload induced early alterations of the subchondral bone plate microstructure towards osteopenia, including significantly decreased percent bone volume and increased bone surface-to-volume ratio (all P ≤ 0.0359 vs. normal). CONCLUSION: The data provide high-resolution evidence that tibiofemoral alignment modulates early OA induced by a medial meniscus injury in adult sheep. Since underload inhibits early OA, these data also support the clinical value of strategies to reduce the load in an affected knee compartment to possibly decelerate structural OA progression.

Internal tibial torsion is associated with medial meniscus posterior horn tears.

PURPOSE: Risk factors for meniscal tears play a decisive role in deciding on treatment and rehabilitation. The purpose of this study was to investigate the effect of tibial rotation on medial meniscus posterior horn tears (MMPHTs). METHODS: This study is a retrospective case-control study. Fifty patients with meniscal tears and 57 knees with intact meniscus were compared. Tibial rotation, femoral version, tibial slope and knee varus were measured in each participant. Knee osteoarthritis was classified according to the Kellgren-Lawrence classification. Demographic characteristics were noted. RESULTS: There were significant differences in the mean tibial torsion angles and mean mechanical axes between the groups. The mean tibial rotation and mean mechanical axis were 26.3° ± 6.7 and 3.7° ± 2.7 in the MMPHT group and 30.3° ± 8.4 and 2.05° ± 2.7 in the control group, respectively (p = 0.008, p = 0.002). CONCLUSION: The current retrospective study has shown that tibial rotation is markedly reduced in patients with MMPHTs. Although the actual mechanism is not clear, the internal torsion of the tibia causes a decrease in the foot progression angle and increases the knee adduction moment, which in turn increases the medial tibial contact pressure. Internal torsion of the tibia, such as knee varus, may play a role in the aetiology of MMPHTs by this way. Whilst there was a significant difference in the mean varus and tibial torsion between the groups, there was no significant difference in the mean femoral version or tibial slope. LEVEL OF EVIDENCE: III.

Online Instruction to Measure Axial Alignment with the Bonesetter App.

Background and objectives: Alignment of the lower extremity is important when treating congenital deformities, fractures, and joint replacement. During the COVID-19 pandemic, AO North America offered an online course on deformity measurement and planning. The Bonesetter app is a deformity planning tool that is freely available online. The purpose of this study was to see how effective an online course was in teaching axial alignment measurement and to assess that skill using an online digital planning tool, the Bonesetter app. Materials and Methods: An online module on axial alignment was provided during the AONA osteotomy course as well as a tutorial on how to use an online digital planning tool (Bonesetter app). The tools within the Bonesetter app allow users to draw digital lines directly on the CT images and measure the exact angle between two planes. Participants in this study were directed to perform these measurements in four different cases that tested different variations of deformity. Results: The measurements were completed correctly in case 1 = 56%, case 2 = 61%, case 3 = 84%, and case 4 = 76%. The standard deviation of angular digital measurements between individuals was ±4.26 degrees. Measuring the angle directly vs. drawing angles to a horizontal line had smaller standard deviations per case (p < 0.005) and less incidents outside 1 standard deviation for each measurement. Errors in adding and subtracting were the most common errors, particularly in relation to femoral anteversion or retroversion. Conclusions: The online course successfully instructed a group of orthopedic surgeons to measure alignment and malalignment of lower limb axial deformities. The Bonesetter app helped participants to learn this skill and identify errors in measurement. The inability to differentiate between anteversion and retroversion of the femur is a common source of error when it occurs and should be a focus of instruction.

Effects of Total Hip Arthroplasty on Axial Alignment of the Lower Limb in Patients with Unilateral Developmental Hip Dysplasia (Crowe type IV).

BACKGROUND: The aim of this study was to evaluate the influence of total hip arthroplasty on axial alignment of the lower limb in adults with unilateral developmental hip dysplasia (Crowe type IV). METHODS: We retrospectively reviewed medical records of 50 adults who underwent total hip arthroplasty, in which the acetabular cup was placed in the anatomical position. The following parameters were measured before surgery, immediately after surgery, and two years later: mechanical axis deviation (MAD), tibiofemoral angle (TFA), femoral offset, hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (LDFA), mechanical medial proximal tibial angle, height of medial femoral condyle, height of lateral femoral condyle, and leg lengthening. Length of the resected femoral segment was also recorded from medical records. RESULTS: Preoperative MAD, TFA, HKA, and LDFA of the ipsilateral lower limb showed significant valgus deformity. MAD of the ipsilateral lower limb and valgus inclination were significantly smaller immediately after surgery than before, while TFA, HKA, femoral offset, and LDFA were significantly larger (P < 0.05). These parameters did not differ significantly between immediately after surgery and two years later (P > 0.05). Ipsilateral extremities were extended by a mean of 2.54 cm (range, 0 to 5.35 cm). The mean length of the femoral resected segment was 3.56 cm (range, 2.03 to 5.74 cm). The contralateral lower limb showed marginally smaller MAD and medial proximal tibial angle after surgery than before, but larger LDFA, TAF, and HKA. CONCLUSIONS: In patients with developmental hip dysplasia who underwent total hip arthroplasty with placement of the acetabular component at the level of the anatomic hip center, axial alignment of the ipsilateral lower limb was immediately altered, and valgus inclination was significantly reduced. The procedure only slightly altered the axial alignment of the contralateral lower limb.

Chronological Changes in Axial Alignment of the Ipsilateral Hip and Knee After Total Hip Arthroplasty.

BACKGROUND: Internal rotation of the hip and lateral patellar tilt increases after total hip arthroplasty (THA). However, it remains unknown whether these parameters change with time after the index THA. METHODS: A total of 91 patients undergoing 2-stage bilateral primary THAs between January 2008 and May 2014 were included to assess the association of chronological changes in internal rotation of the hip or lateral patellar tilt with anthropometric and perioperative parameter and changes in alignment after the index THA. Chronological changes were assessed as changes between postoperative computed tomography on the index surgery and the preoperative computed tomography on the contralateral THA. Internal rotation of the hip was defined as the angle between the posterior intercondylar line and a line passing through the posterior inferior iliac spines. Lateral patellar tilt was defined as the angle between the posterior intercondylar line and a line joining the medial and lateral edges of the patella. RESULTS: Internal rotation of the hip and lateral patellar tilt changed until 2 years after the index surgery by a mean of -2° (range -17.3° to 17.7°) and -2° (range -18.2° to 5.3°), respectively. Adductor tenotomy was associated with increasing internal rotation of the hip with time (adjusted R2 0.076); leg lengthening and larger preoperative femorotibial angle were associated with decreasing lateral patellar tilt with time (adjusted R2 0.159). CONCLUSION: Both internal rotation of the hip at rest and lateral patellar tilt decreased by approximately 2° until 2 years after surgery and there was a large variation in chronological change.

Effect of arthroscopic resection for discoid lateral meniscus on the axial alignment of the lower limb.

PURPOSE: This study was designed to investigate the changes in the lower limb axial alignment and knee joint function after arthroscopic resection of discoid lateral menisci. METHODS: Pre-operative and post-operative full-length weight-bearing radiographs of the lower limb were obtained from 60 patients with discoid lateral menisci from August 2015 to August 2016. Twenty-four patients were treated with meniscectomy and 36 cases were treated with meniscoplasty. The axial alignment of the lower limb was measured, and changes in the lower limb axial alignment before and after surgery were analyzed. The effects of differing degrees of meniscal resection on the lower limb axial alignment were compared and analyzed. Knee joint function on the affected side was scored using the Lysholm knee scoring, Tegner activity, and International Knee Documentation Committee (IKDC) subjective scales before surgery and one, six and 12 months after surgery. RESULTS: There were apparent changes in the lower limb axial alignment after surgery (p < 0.01). The changes were more conspicuous after a total meniscectomy than a meniscoplasty but were insignificant (p > 0.05). Intragroup comparisons of the Lysholm knee, IKDC, and Tegner scores before and after surgery revealed significant differences (p < 001). However, the differences were not significant between the two surgical approaches (p > 0.05). CONCLUSION: For those with considerable genu varum or genu valgum after surgery, individualized therapy should be developed to correct the lower limb axial alignment and to prevent articular cartilage degeneration. Arthroscopic resection of a discoid lateral meniscus greatly improves knee joint function.

Femoral bow predicts postoperative malalignment in revision total knee arthroplasty.

Diaphyseal bowing may compromise axial alignment in revision total knee arthroplasty (TKA). 277 patients undergoing revision TKA were evaluated for coronal bowing and hip-knee-ankle (HKA) axis. The mean femoral bow was 1.52° ± 0.18° varus (-10.1° to +8.4°). The mean tibial bow was 1.25° ± 0.13° valgus (-5.9° to +10°). HKA axis averaged 3.08° ± 0.35° varus preoperatively compared to 0.86° ± 0.25° varus postoperatively. Inter-rater and intra-rater reliability was high. Femoral bow greater than 4° significantly correlated with postoperative HKA axis malalignment (r = 0.402, P = 0.008). 39.7% of patients deviated 3° or greater from a neutral mechanical axis with a significant difference in femoral bow (0.94° ± 0.31°, P = 0.003). Diaphyseal bowing clearly has an important effect on postoperative limb alignment in revision TKA.

Initial graft tension affects patellofemoral alignment during anatomical anterior cruciate ligament reconstruction.

BACKGROUND: This study aimed to evaluate the effects of the differences in initial graft tension (IGT) on patellofemoral alignment in the axial plane after anatomical anterior cruciate ligament reconstruction (ACLR). METHODS: A total of 102 patients who underwent primary anatomical ACLR using a bone-patellar-tendon-bone autograft were enrolled. The grafts were fixed with maximum manual force at full knee extension (higher graft tension; H group) and with 5-20 N at 20° knee flexion which corresponded to 80 N at full knee extension (lower graft tension; L group) pulls in 39 and 63 patients, respectively. All patients underwent computed tomography of the bilateral knee joints with knee extension 1 week postoperatively. The patellofemoral alignment (sulcus angle, lateral trochlear inclination angle, lateral patellofemoral angle (LPFA), condylar-patellar angle (CPA) (lateral facet, patellar tilt), congruence angle, and bisect offset index) on the axial computed tomography images were evaluated, and the side-to-side differences (SSDs) between the injured knee and the contralateral knee were calculated. RESULTS: Congruence angle SSD was remarkably higher in the H group than in the L group (3.8 ± 4.7 vs. 0.4 ± 5.7, P < 0.01). Furthermore, the LPFA SSD and CPA (patellar tilt) SSD were significantly higher in the H group (-1.8 ± 3.1 vs. -0.4 ± 2.7, P = 0.04 and -1.6 ± 2.8 vs. -0.3 ± 2.7, P = 0.04, respectively). CONCLUSIONS: A higher IGT during anatomical ACLR induces a lateral shift and tilt of the patella against the femur immediately after surgery compared with the lower IGT.

Femoral internal torsion greater than twenty-five degrees and/or external tibial torsion greater than thirty degrees as measured by computed tomography are threshold values for axial alignment correction in patellofemoral instability.

OBJECTIVES: Patellofemoral instability (PFI) has multiple predisposing anatomic factors, including ligamentous hyperlaxity, coronal and axial malalignment, patella alta, trochlea dysplasia, excessive lateral patellar tilt, and excessive lateral Q vector. Yet, few studies have analyzed surgical thresholds for performing axial alignment corrective osteotomies in the treatment of PFI and patella maltracking. The objective of this systematic literature review was to determine if there is a threshold for axial plane alignment that triggers surgical correction for the treatment of patellar instability in the published literature. METHODS: Using a predetermined search strategy, a systematic literature search of 10 major databases and gray literature resources was completed. Only studies reporting on patellar instability and outcomes were included. Radiologic indications, additional procedures, outcomes, and complications were reported. Titles and abstracts were screened, and full-text manuscripts were then selected and extracted. Variables related to radiographic and clinical parameters, patient demographics, surgery performed, surgical correction, complications, and reoperations were recorded preoperatively and postoperatively. RESULTS: A total of 1132 abstracts and titles were screened by two reviewers, yielding 15 eligible studies. The reported threshold identified in our study for axial plane alignment that triggers surgical correction in most of the published literature when discussing PFI was either tibial torsion greater than 30° and/or femoral anteversion greater than 25°. Following rotational osteotomy of one or both long bones, one study (7%) reported improvements in tubercle-sulcus angle, two studies (13%) reported improvements in femoral-tibial angle, and four studies (27%) reported decreases in tibial torsion. For patient-reported outcomes, seven studies (47%) reported improvement in the Kujala score, five studies (33%) reported postoperative improvement in Lysholm, and four studies (27%) reported improvement in the International Knee Documentation Committee (IKDC) score. Nine studies (60%) reported preoperative femoral anteversion; however, only two studies compared pre- and post-operative values (one study reported a decrease in anteversion and another study reported an increase in anteversion). CONCLUSION: When treating PFI, the reported threshold for axial plane alignment that triggers surgical correction in most of the published literature was tibial torsion greater than 30° and/or femoral anteversion greater than 25° as measured by CT. However, there is no consensus on the axial alignment measurement technique. LEVEL OF EVIDENCE: III.

Only 26% of Native Knees Show an Identical Coronal Functional Knee Phenotype in the Contralateral Knee.

BACKGROUND: A comprehensive exploration evaluating left-to-right knee symmetry across all anatomical planes utilizing three-dimensional (3D) scans stands absent from the existing body of research. Therefore, the primary objectives of this investigation involved examining potential differences and resemblances in alignment and structure between left and right non-osteoarthritic (native) knees in various planes (coronal, sagittal, and axial) using three-dimensional single-photon emission computed tomography/computed tomography (SPECT/CT) images. METHODS: A total of 282 native knees from 141 patients were retrospectively gathered from the hospital's records. Patients, aged between 16 and 45, who underwent Tc99m-methyl diphosphonate SPECT/CT scans for both knees, adhering to the Imperial Knee Protocol, were included. A statistical analysis was conducted, including 23 knee morphometric parameters, comparing left and right knees, and classifying them based on functional knee phenotypes across the coronal, sagittal, and axial planes. RESULTS: Regarding the functional coronal knee phenotype, 26% of patients (n = 37) exhibited identical phenotypes in both knees (p < 0.001). Significant correlated similarities between the left and right knees were observed in the coronal plane (Pearson's r = 0.76, 0.68, 0.76, 0.76, p < 0.001) and in several morphometric measures in the sagittal plane (Pearson's r = 0.92, 0.72, 0.64, p < 0.001). Moderately correlated similarities were noted in the axial plane (Pearson's r = 0.43, 0.44, 0.43, p < 0.001). CONCLUSIONS: Only 26% of native knees exhibit an identical coronal phenotype in their contralateral knee, whereas 67% have the adjacent coronal phenotype. Strongly correlated resemblances were established across various left and right knee morphometric parameters in the coronal, sagittal, and axial planes. These findings could enhance decisions in procedures like total knee arthroplasties or osteotomies, where alignment is key to outcomes, and reveal a potential for future artificial intelligence-driven models to improve our understanding and improve personalized treatment strategies for knee osteoarthritis.

Effect of Tibiofemoral Rotation Angle on Graft Failure After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Coronal and sagittal malalignment of the knee are well-recognized risk factors for failure after anterior cruciate ligament (ACL) reconstruction (ACLR). However, the effect of axial malalignment on graft survival after ACLR is yet to be determined. PURPOSE: To evaluate whether increased tibiofemoral rotational malalignment, namely, tibiofemoral rotation angle (TFA) and tibial tubercle-trochlear groove (TT-TG) distance, is associated with graft failure after ACLR. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: In this retrospective matched control study of a single center's database, 151 patients who underwent revision ACLR because of graft failure (ACLR failure group, defined as symptomatic patients with anterior knee instability and an ACL graft tear appreciated on magnetic resonance imaging [MRI] and confirmed during arthroscopic surgery) were compared with a matched control group of 151 patients who underwent primary ACLR with no evidence of failure after ≥2-year follow-up (intact ACLR group). Patients were matched by sex, age, and meniscal injury during primary ACLR. Axial malalignment was assessed on preoperative MRI through the TFA and the TT-TG distance. Sagittal alignment was measured through the posterior tibial slope on MRI. The optimal TFA cutoff associated with graft failure was identified by a receiver operating characteristic curve. The Kaplan-Meier curve with log-rank analysis was performed to evaluate the influence of the TFA on ACLR longevity. RESULTS: The mean age was 25.7 ± 10.4 years for the ACLR failure group and 25.9 ± 10.0 years for the intact ACLR group. Among all the included patients, 174 (57.6%) were male. In the ACLR failure group, the mean TFA was 5.8°± 4.5° (range, -5° to 16°), while it was 3.0°± 3.3° (range, -3° to 15°) in the intact ACLR group (P < .001). Neither the TT-TG distance nor the posterior tibial slope presented statistical differences between the groups. The receiver operating characteristic curve suggested an optimal TFA cutoff of 4.5° for graft failure (area under the curve = 0.71; P < .001; sensitivity, 68.2%; specificity, 75.5%). Considering this a threshold, patients who had a TFA ≥4.5° had 6.6 times higher odds of graft failure compared with patients with a TFA <4.5° (P < .001). Survival analysis demonstrated a 5-year survival rate of 81% in patients with a TFA <4.5°, while it was 44% in those with a TFA ≥4.5° (P < .001). CONCLUSION: An increased TFA was associated with increased odds of ACLR failure when the TFA was ≥4.5°. Measuring the TFA in patients with ACL tears undergoing reconstruction may inform the surgeon about additional factors that may require consideration before ACLR for a successful outcome.

Setting the Tibial Component Rotation Based on Femoral Landmarks Allows Congruent Knee Kinematics in Robotic-Assisted Medial Unicompartmental Knee Replacement.

The accurate positioning of the prosthetic components is essential for achieving successful results in medial unicompartmental knee arthroplasty (mUKA). The tibial component rotation in image-based robotic-assisted UKA is usually based on tibial bony landmarks matched to the pre-operative CT model. The study aimed to evaluate whether setting the tibial rotation on femoral CT-based landmarks allows congruent knee kinematics. We retrospectively analyzed data from 210 consecutive image-based robotic-assisted mUKA cases. In every case, we set the tibia rotation landmark parallel to the posterior condylar axis and centered it on the trochlea groove defined on the preoperative CT scan. The implant positioning was primarily set parallel to this rotation landmark and then adjusted based on tibial sizes avoiding component over- or under-hang. During surgery, we recorded the knee kinematics under valgus stress to reduce the arthritic deformity. A femoral-tibial contact point was recorded over the entire range of motion and displayed as a tracking profile on the tibia implant. The femoro-tibial tracking angle (FTTA) was then calculated based on a tangent line to the femoro-tibial tracking-points and the difference to the femur-based rotation landmark. In 48% of the cases, we could position the tibia component exactly to the femoral rotation landmark, whereas in 52% of cases, minimal adjustments were made to avoid component's under- or over-hang. The mean tibia component rotation (TRA) with reference to our femur-based landmark was +0.24° (SD ± 2.9°). The femur-based tibia rotation landmark showed a high correspondence to the FTTA with 60% of the cases having less than 1° of deviation. Mean FTTA was +0.7° (SD ± 2.2°). The mean difference between the absolute value of the TRA and the FTTA (|TRA| - |FTTA|) was -0.18° (SD ± 2°). Setting the tibial component rotation based on CT scan femoral landmarks and not on tibial anatomical landmarks is a reliable method to obtain congruent knee kinematics during image-based robotic-assisted medial UKA with less the 2° deviations on average.

Partial resection of lateral discoid meniscus changes lower limb axial alignment - A retrospective cohort study.

AIM: This study aimed to explore the changes in lower limb axial alignment and knee joint function after arthroscopic partial resection of the discoid lateral meniscus. METHODS: Preoperative and postoperative full-length weight-bearing radiographs of the lower limb were obtained from a total of 161 patients with lateral menisci tears from September 2018 to September 2020 who underwent partial meniscal resection. The patients were divided into discoid meniscus group (DMG) and ordinary meniscus group (OMG). The measured mechanical axis deviation (MAD), proximal tibia angle (PTA), and distal femoral angle (DFA) in the axial alignment of the lower limb were determined before and after surgery. Knee joint function on the affected side was determined using the International Knee Documentation Committee (IKDC) subjective scale and the Lysholm knee scoring scale before surgery and at one, six, 12, and 24 months after surgery. RESULTS: For MAD and DFA, there were statistically significant differences between the preoperative and postoperative findings within each group (P < 0.01); the MAD and DFA were smaller after surgery. The difference in preoperative and postoperative PTA of the DMG was statistically significant (P < 0.01), meaning that the PTA becomes larger after surgery. The differences in preoperative and postoperative PTA of the OMG, preoperative PTA between the two groups, and postoperative PTA between the two groups were not statistically significant (P > 0.05). Intragroup comparisons of the IKDC subjective scale and the Lysholm knee scoring scale before and after surgery revealed significant differences (P < 0.05). CONCLUSION: Arthroscopic partial resection of the discoid lateral meniscus is a safe and effective surgical method that can significantly improve knee joint function. Although the axial arrangement of the lower limbs will be slightly changed in the early stage, it will still be within the normal range after surgery in patients with normal lower limb axial alignment. For patients with varus or valgus before surgery, this procedure should be applied with caution.

Radiographic Evaluation of Pediatric Patients with Patellofemoral Instability.

PURPOSE OF REVIEW: The purpose of this review is to highlight the radiographic assessments of utility in the evaluation of a pediatric patient with patellofemoral instability to facilitate a thorough work-up. Understanding of these measures is useful in understanding evolving research in this field, providing accurate patient risk assessment, and appropriately directing surgical decision-making. RECENT FINDINGS: Recent literature has broadened the radiographic characterization of the pediatric patellar instability and its anatomic risk factors. Knee MRI can inform the assessment of skeletal maturity and novel axial alignment measurements may enhance our identification of patients at increased risk of recurrent instability. Additional improvements have been made in the objective measurement and classification of trochlear dysplasia. Knee MRI-based skeletal age assessments may obviate the need for hand bone age assessments in growing children with patellofemoral instability. Novel objective measures exist in the evaluation of pediatric patellar instability both in the assessment of axial alignment and trochlear dysplasia. Future work should focus on how these measures can aid in guiding surgical decision-making.

The 3-triangle method preserves the posterior tibial slope during high tibial valgus osteotomy: first preliminary data using a mathematical model.

PURPOSE: Despite much improved preoperative planning techniques accurate intraoperative assessment of the high tibial valgus osteotomy (HTO) remains challenging and often results in coronal over- and under-corrections as well as unintended changes of the posterior tibial slope. Noyes et al. reported a novel method for accurate intraoperative coronal and sagittal alignment correction based on a three-dimensional mathematical model. This is the first study examining preliminary data via the proposed Noyes approach for accurate intraoperative coronal and sagittal alignment correction during HTO. METHODS: From 2016 to 2020 a total of 24 patients (27 knees) underwent HTO applying the proposed Noyes method (Noyes-Group). Radiographic data was analyzed retrospectively and matched to patients that underwent HTO using the conventional method, i.e., gradual medial opening using a bone spreader under fluoroscopic control (Conventional-Group). All operative procedures were performed by an experienced surgeon at a single orthopaedic university center. RESULTS: From the preoperative to the postoperative visit no statistically significant changes of the posterior tibial slope were noted in the Noyes-Group compared to a significant increase in the Conventional-Group (p = 0.01). Regarding the axial alignment no significant differences between both groups were observed pre- and postoperatively. The number of over- and under-corrections did not differ significantly between both groups. Linear regression analysis showed a significant correlation of the postoperative medial proximal tibial angle (MPTA) with the position of the weightbearing line on the tibial plateau. CONCLUSION: The 3-triangle method by Noyes seems to be a promising approach for preservation of the posterior tibial slope during HTO.

Enhancing rotational placement of reconstruction prostheses of the distal femur after sarcoma resection.

INTRODUCTION: Currently there are no accepted international guidelines for the correct placement of reconstruction prostheses in the axial plane of the femur after en bloc resection. The most accepted method is based on the linea aspera as an intraoperative landmark, indicating posterior. This study was conducted to address the reliability of the linea aspera as a landmark for rotational alignment. MATERIAL AND METHODS: 50 CT angiographies of the right limb were used for this purpose. These 2D images were reconstructed into 3D models using proprietary software (materialize NV, Leuven, Belgium). The posterior condylar line was used as a reference axis. The orientation of the linea aspera was described as the angle between the perpendicular line to the PCL, through the center of the diaphysis, and the lateral (α) and medial labium (ß). RESULTS: The linear mixed model shows that the α- and ß-angles are significantly associated with the distance from the joint line (p<0.001) and vary significantly between subjects (p<0.001). The α-angle has the lowest variance and approximates more closely true posterior, while the median ß-angle never overlaps true posterior. DISCUSSION: When a surgeon would blindly rely on the linea aspera as a posterior landmark roughly 78% of the femoral implants would exceed the accepted ±3° deviation around the surgical transepicondylar axis (sTEA) as defined in total knee replacement. The linea aspera is not a reliable landmark for axial rotation of femoral implants. The position is highly dependent on the osteotomy height and in addition differs between individual patients. Preoperative assessment of the linea aspera is advocated in order to reduce the risk of malrotation. As the height of the osteotomy cannot always be determined correctly preoperatively, a table was designed as a guideline for how much a deviation from the planned resection height will affect the rotation of the implant.

Anterior-Posterior (AP) Calcaneal Profile View: A Novel Radiographic Image to Assess Varus Malalignment.

BACKGROUND: Assessing and correcting malalignment is important when treating calcaneus fractures. The Harris axial view is commonly utilized to assess varus deformity but may be inherently inaccurate due to its tangential nature. The anterior-posterior (AP) calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. METHODS: Five nonpaired ankle cadaveric specimens were used in this investigation. Oblique osteotomies were created in relation to the long axis, and varus deformities were produced by inserting solid radiolucent wedges into the osteotomies to create models of 10, 20, and 30 degrees of angulation of the calcaneal tuberosity. Specimens were imaged using both the Harris axial view and the AP calcaneal profile view. RESULTS: For cadavers with 10 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 10.9 ± 4.8 (range, 5.5-16.0) degrees and 13.0 ± 5.5 (range, 7.3-20.9) degrees, respectively. For cadavers with 20 degrees of actual varus angulation, the mean Harris view angle and the AP calcaneal profile view angle were 11.5 ± 2 (range, 8.2-13.6) degrees and 18.1 ± 4.8 (range, 11.7-23.5) degrees, respectively (P = .005). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle (P = .012) and actual angulation (P = .011). For cadavers with 30 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 18.3 ± 4.3 (range, 13.3-23.6) degrees and 28.3 ± 2.9 (range, 24.4-31.1) degrees, respectively (P < .001). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle (P = .001) and actual angulation (P < .001). There was no significant difference between the AP calcaneal profile view angle and actual angulation (P > .999). CONCLUSION: The AP calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. While both views demonstrated similar measurement error for lesser degrees of varus malalignment, the AP calcaneal profile view demonstrated more accurate measurement of increasing heel varus compared with the Harris view. CLINICAL RELEVANCE: The AP calcaneal profile view could be used in addition to other radiographic views when treating displaced, intra-articular calcaneus fractures to help optimize correction of hindfoot alignment.

[Clinical application and research status of open wedge high tibial osteotomy].

OBJECTIVE: To summarize the clinical application and research status of open wedge high tibial osteotomy (OWHTO). METHODS: Relevant literature at home and abroad was reviewed, and the clinical application, effectiveness and complications, technical comparison, and surgical skills of OWHTO were summarized and analyzed. RESULTS: OWHTO is an effective treatment for mild to moderate medial compartment osteoarthritis due to knee varus. This method can delay the injury process of medial compartment of the knee, delay the time of total knee arthroplasty, and even avoid joint replacement surgery by adjusting the axial alignment of the lower extremity to the non-pathological lateral compartment through osteotomy and orthopedic. OWHTO has the advantages of small incision, dynamic adjustment of the axial alignment of the lower extremity, accurate correction of malformation, and rapid postoperative recovery. CONCLUSION: With the development of surgical instruments and techniques, OWHTO once again enter the sight of orthopedic surgeons. This technique can solve the pain symptoms of arthritis, correct the tibial varus deformity and reconstruct the axial alignment of the lower extremity, and satisfactory clinical results has been obtained.

Intraoperative validation of bone cut accuracy of a pinless smart touch-screen navigation system device in total knee arthroplasty.

PURPOSE: Primary objective in most of the published literature on computer-assisted total knee arthroplasty (TKA) has so far been the comparison of axial alignment and components position, obtained either through navigation systems or through conventional instrumentation. We have found no studies aimed at assessing the intraoperative reliability of a navigation system in relation to bone cuts height. Aim of our study was therefore to establish bone cut accuracy of a pinless navigation system. METHODS: From January 2014 to February 2016, 44 consecutive patients requiring total knee replacement (TKR) were enrolled in a prospective study. Primary end point of the study was to assess the accuracy of the DASH iPOD TOUCH Navigation System (Brainlab AG, Feldkirchen, Germany) by measuring the real thickness of both tibial and femoral osteotomies. We compared the data indicated by the navigation system with the intraoperative anatomical measurements done with the aid of a caliper. In addition, the radiographic alignment was compared with the data derived from the navigator. RESULTS: The device proved to be precise. Differences between the two methods of measurement are distributed over a millimeter range. Radiological measurements showed that 95.5% of tibial components were within the range of 3° varus/valgus; same results were obtained by the navigation system; instead, 90.1% of femoral components were within the range of 3° varus/valgus based on the radiological measurement, whereas according to the navigation system, 86.4% were in this range. CONCLUSIONS: The DASH iPOD TOUCH Navigation System is a precise and reliable instrument to assist in TKA navigation.

A shortened uncemented stem offers comparable positioning and increased metaphyseal fill compared to a standard uncemented stem.

BACKGROUND: Shortened stems are increasingly used in uncemented total hip arthroplasty (THA) as they represent a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems. The purpose of this study was to compare the metaphyseal canal-fill ratio (CFR) and axial alignment of a shortened double-tapered stem with those of a standard stem. The hypothesis was that the shortened stem would achieve greater metaphyseal fill and comparable axial alignment. METHODS: The authors reviewed routine follow-up anteroposterior radiographs taken 2 months after THA to evaluate metaphyseal fill and axial alignment of a shortened stem (n = 96) and a standard stem (n = 101). The CFR was calculated at the level of the tip and superior margin of the lesser trochanter. Stem alignment was defined as the angle between the stem axis and the proximal anatomic femoral axis. Stems were classified as being in varus or valgus alignment if they deviated by more than 3° from the anatomic axis of the femur. RESULTS: Hips implanted with shortened and standard stems had comparable demographics and axial alignment (1.1° ± 1.7° vs 0.8° ± 1.2°; p = 0.331). However, varus alignment was observed in 5% of shortened stems compared to only 1% of standard stems, though this difference was not significant (p = 0.111). The femoral CFR was greater using shortened stems than using standard stems, both at the level of the tip of the lesser trochanter (0.91 ± 0.05 vs 0.85 ± 0.08; p < 0.001) and at its superior margin (0.76 ± 0.06 vs 0.72 ± 0.07; p < 0.001). CONCLUSIONS: Compared to the standard stem, the shortened stem had increased metaphyseal filling and equivalent alignment. These findings suggest that shortened stems could provide adequate metaphyseal fixation and correct alignment. Further studies remain necessary to evaluate how shortened stems perform in terms of osseointegration, clinical outcomes and survival.