Neutral Alignment Research Articles

How Much Subtalar and Ankle Joint Surface are Actually Destroyed when Reaming for Tibiotalocalcaneal (TTC) Nailing? A Cadaveric Study

Category: Ankle; Trauma Introduction/Purpose: Tibiotalocalcaneal (TTC) nailing in the setting of acute ankle trauma has become increasingly popular over the last decade, with expanding indications. Potential advantages of TTC nailing include: less soft tissue dissection, decreased wound burden, and earlier weightbearing. No consensus exists as to whether formal joint preparation is necessary, and at one or both joints. While some argue that joint preparation is not necessary due to inherent joint destruction from the injury and reaming during TTC nailing, others advocate for preparation to facilitate fusion and ensure no further motion occurs at the joint which could lead to nonunion and/or hardware failure. The purpose of this study was to quantify the proportion of ankle and subtalar joint articular surface destruction associated with reaming for TTC nail fixation. Methods: Twelve cadaver feet from 6 specimens were procured. The specimens were reduced and pinned into neutral ankle dorsiflexion and neutral hindfoot alignment. Prior to reaming, each specimen was secured in a simulated supine position. Per standard TTC nailing technique, a 3.0 millimeter (mm) guide wire was inserted under fluoroscopy, retrograde from the calcaneus, through the talus, and into the tibia, followed by a 12mm opening reamer. The specimens were then dissected, exposing the tibial plafond (TP), talar dome (TD), posterior facet of the talus (PFT), and posterior facet of the calcaneus (PFC). Clinical images of each joint were obtained at an angle of 90 degrees and 12 centimeters (cm) from the joint surface. The images were processed using the ImageJ software platform. The total joint surface area, area of articular destruction, and the remaining joint surface area were calculated. The percentage of joint destruction associated with reaming was then calculated. Results: The mean surface area values and percentages of articular surface destruction are summarized in Table 1. The mean surface area (cm2) after reaming was 11.82, 13.70, 9.23, and 7.79 for the TP, TD, PFT, PFC, respectively. The percentage of articular cartilage destruction was 9.32%, 10.33%, 8.89%, and 10.28% for the TP, TD, PFT, PFC, respectively. No joint destruction was observed in the middle facets of the subtalar joint. Conclusion: This study demonstrates that reaming for TTC nail placement involves only a small portion (roughly 8-10%) of each of the articular surfaces of the ankle and subtalar joints. Violation of the middle facet of the subtalar joint did not occur. These results suggest that a significant portion of hindfoot articular surface remains after reaming for TTC nail. Formal joint preparation may be beneficial to aid with fusion after TTC nail placement, particularly when used in younger, more active individuals who sustain hindfoot and ankle trauma.

Influence of Double Hindfoot Arthrodesis and the Sequence of Joint Fusion on Ankle Kinematics: A Cadaveric Gait Simulation Study

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Although double hindfoot arthrodesis (subtalar and talonavicular) provides pain relief and deformity correction for patients with end-stage arthritis, altered ankle biomechanics may occur following these procedures. Furthermore, it has been reported that hindfoot fusions may lead to progressive ankle degenerative changes and a higher failure rate in patients undergoing total ankle arthroplasty. Previous biomechanical studies demonstrated that hindfoot fusion altered ankle joint kinematics and contact mechanics during simplified loading scenarios, but the effect during dynamic activity is unknown. Therefore, this study sought to quantify the changes in ankle kinematics after a double hindfoot arthrodesis during the stance phase of simulated gait. In addition, we sought to assess whether the sequence in which joints are fused plays a role in altering ankle kinematics. Methods: Fourteen mid-tibia specimens underwent stance phase simulations of level walking using a validated six-degree of freedom robot. All specimens had neutral hindfoot alignment. An eight-camera motion system tracked reflective markers in the tibia, talus, calcaneus, and navicular bones. Simulated arthrodeses of the subtalar and talonavicular joints were performed using two 7.0mm and two 5.5mm crossing screws, respectively. The subtalar alignment was set at 5º valgus, and the talonavicular at neutral abduction/adduction. Fluoroscopic images confirmed proper screw position and hindfoot alignment. Each specimen was tested in three conditions: pre-arthrodesis(intact), isolated arthrodesis(subtalar or talonavicular joint), and double arthrodesis(double). Specimens were further divided into two groups depending on whether the subtalar(STDouble) or talonavicular(TNDouble) joint was fused first. Ankle kinematics were calculated for each condition for the entire cohort of specimens and each of the two groups. Bias-corrected 95% confidence intervals of the difference in ankle kinematics relative to the intact condition were constructed. Results: Double hindfoot arthrodesis significantly altered ankle kinematics(Figure1A). Ankle plantarflexion decreased during heel strike by up to 2.0° on average and increased during toe-off by 6.5° compared to the intact condition. Ankle eversion increased by 1.5º and 2.5º on average during mid- and late stance, respectively. Internal rotation decreased during midstance by 1.1º on average and increased in late stance by 4.5°. The order in which hindfoot joints were fused significantly influenced ankle kinematics(Figure1B). On average, the TNDouble condition produced 2.3º and 3.5º more ankle eversion during the mid- and late stance, respectively, and 2.10° more ankle internal rotation during the early stance compared to the STDouble condition (not shown). Significant changes were also present after isolated hindfoot arthrodeses and remained consistent after the double arthrodesis. Conclusion: Double hindfoot arthrodesis significantly altered ankle kinematics throughout stance. Ankle kinematics also differed depending on which joint was fused first. Notably, the TNDouble condition produced more ankle internal rotation during early stance and more ankle eversion during mid- and late stance compared to the STDouble condition. This finding suggests that the sequence in which joints are fused affects the resultant ankle kinematics. Finally, the kinematic changes after isolated hindfoot arthrodesis remained consistent after incorporating the second joint into the fusion. It appears that once one joint needs to be fused, avoiding the double arthrodesis may not necessarily protect the ankle.

Accuracy of a Patient-Specific Total Ankle Arthroplasty Instrumentation.

Total ankle arthroplasty (TAA) is a preferred surgical option for end-stage ankle osteoarthritis; however, it is a demanding procedure with a higher historical rate of revision compared with ankle fusion. Patient-specific instrumentation (PSI) has been introduced to optimize prosthesis alignment and theoretically overall improve TAA outcomes. The goal of this study is to report on the experience and surgical outcomes of one implant with specific evaluation of the accuracy and reproducibility of the system with respect to prosthesis alignment and prediction of implant size. A retrospective, multicentered study involving 4 foot and ankle fellowship-trained orthopaedic surgeon's patients undergoing TAA between January 1, 2015, and December 31, 2018, using the PROPHECY PSI system. 80 TAA procedures were performed. On average the postoperative tibial component alignment was 89.9 (range, 86.1-96.5) degrees in the coronal plane, with a mean sagittal alignment of 88.1 (range, 81.3-96.7) degrees. The mean deviation from neutral sagittal alignment improved from 4.9 ± 3.9 degrees preoperatively to 2.7 ± 1.7 degrees postoperatively, whereas the mean coronal alignment improved from 3.3 ± 2.5 degrees to 1.3 ± 1.1 degrees. The PSI software correctly determined the tibial implant size in 70 patients (89%). Prediction of talar implant sizing was less accurate than the tibial component, with 56 patients (71%) using the predicted sized implant. The overall implant survival at a mean follow-up of 45 months (range, 27-76) was 97.5%. We found that this PSI system accurately and reliably assisted in implant total ankle prosthesis positioning within a clinically acceptable margin and without significant outliers. Prediction of implant size was not as accurate as component orientation. Level III, retrospective study.

192 Preserving Glenoid Subchondral Bone in aTSR

Abstract Aim Glenoid loosening remains a major concern in anatomical Total Shoulder Replacement (aTSR). Preoperative planning software and patient specific guides allow implantation optimization in aTSR. This study aims to examine and compare the amount of bone resected with prescribed adjusted angles to respecting the subchondral plate with minimal resection, using a freehand technique. Method Two groups of shoulder CT scans were assessed, normal and osteoarthritic of patients who had undergone aTSR. Preoperative planning software was used to place the glenoid component in prescribed adjusted angles, with neutral (0o,0o), retroverted (-10o,0o) and inclined alignment (0o,10o). This was then compared to positioning the component using a freehand technique, whereby the component was placed in a position to maintain the subchondral plate with minimal bone loss and respecting the integrity of the vault. Results The number of CT scans was 68, 34 normal and 34 osteoarthritic. The freehand technique resulted in statistically superior cortical bone seating in the osteoarthritic group with a mean (standard deviation) of 53.27% (14.32), while neutral alignment resulted in 36.68% (10.81), retroversion 40.40% (13.06), and inclination 39.34% (13.52), p<0.001. Similarly in the normal scans, cortical bone seating in the freehand scenario was 46.71% (15.96), neutral 25.65% (12.27), retroverted 26.73% (15.03), and inclined 32.93% (12.12), p<0.001. Conclusions The freehand method for positioning the guidewire resulted in significantly superior cortical bone seating, when compared to prescribed adjusted angles. Applying this technique in the clinical setting may achieve superior glenoid component seating and hence reduce the risk of aseptic loosening in aTSR.

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

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

Reduction of Atlanto-Occipital Dislocation After Cervical Collar Removal

A 39-year-old male pedestrian-hit-by-car was transferred to our institution with atlantooccipital dislocation (AOD) on outside computed tomography (CT) imaging. On arrival he had a rigid cervical collar in place. Given the reported AOD, we placed the patient flat, removed the cervical collar, and supported the head in neutral alignment with sandbags. Due to a technical issue uploading his prior imaging to our system, the patient underwent repeat CTs at our center. Subsequently, after the outside images were uploaded, we were able to compare his cervical spine CT images before and after removing his cervical collar. On comparison, we noted a substantial reduction in AOD after collar removal. We hope this serves as a reminder of this key step in managing a rare but deadly clinical entity and a small demonstration of the efficacy of this intervention.

Micro Electromechanical System Navigation Assists Femoral Extramedullary Alignment Osteotomy in Total Knee Arthroplasty: A Single-Blind Randomizing Study.

A micro-electromechanical system (MEMS) was developed based on spatial alignment and navigation technology to assist femoral extramedullary alignment osteotomy (FEAO) in total knee arthroplasty (TKA). The system can locate and adjust the femoral distal condylar osteotomy (FDCO) to obtain a better femoral prosthesis placement. It is a portable navigation device and provides an innovative approach for FDCO. Sixty patients who suffered from severe knee osteoarthritis who underwent unilateral TKA from May 14, 2021 to May 30, 2022 were randomly divided into a MEMS-FEAO group and a conventional femoral intramedullary alignment osteotomy (FIAO) group, with 30 cases in each group for a controlled retrospective study. The hip-knee-ankle angle (HKAA) of the lower limb was measured before and after surgery, the femoral valgus angle (FVA) was measured preoperatively, and the femoral prosthesis valgus angle (FPVA) and the femoral prosthesis flexion angle (FPFA) were measured postoperatively following computed tomography imaging protocols. Measurement data is statistically described as mean ± standard deviation c. The count data is described by frequency (constituent ratio) using the rank sum test. A total of 6.7% (2/30) of FEAO compared to 20.0% (6/30) of FIAO cases were postoperative deviations where the HKAA exceeded ±3° of neutral alignment (p < 0.05). The postoperative HKAA was 178.74° ± 1.56° versus 176.64° ± 3.39° (p < 0.05), the HKAA deviation was 1.25° ± 1.56° versus 3.36° ± 3.40° (p < 0.05), and the FPFA was 4.85° ± 2.46° versus 6.60° ± 1.86°(p < 0.05). Therefore, the differences were all statistically significant between the two groups. However, the FPVA was -0.59° ± 2.73° versus -0.80° ± 2.85° (p > 0.05), and there was no statistical significance between the two groups. The MEMS-FEAO system can improve the accurate alignment and can be utilized as a locator to obtain the best femoral prosthesis placement in TKA and significantly reduce the rate of poor force line of the lower limb.

Accuracy and outcome of a handheld accelerometer-based navigation device compared to conventional alignment method in total knee arthroplasty in a Chinese population

Background Total knee arthroplasty (TKA) is a successful procedure in treatment of degenerative disease of the knee, and optimal component placement is essential for long-term implant survival. The purpose of this study was to compare the accuracy of the accelerometer-based KneeAlign 2 (KA2) navigation system against conventional methods for accurate positioning of the femoral and tibial components in TKA in a Chinese population. Methods A total of 123 (37 conventional and 86 KA2) cases of elective primary TKA were reviewed. Hip-knee-ankle (HKA) angle, mechanical lateral distal femoral angle (mLDFA), and anatomical lateral distal femoral angle (aLDFA) were measured from hip-to-ankle EOS radiographs. Accuracy of conventional alignment and KA2 navigation system was assessed by measuring the difference between intraoperative goal and postoperative radiographic measurements of the components for each respective case. Results There was no significant difference between conventional alignment methods and KA2 navigation in achieving a neutral mechanical alignment of the lower limb. KA2 navigation was significantly more accurate than conventional alignment methods for optimal positioning of the tibial component in both the coronal and sagittal plane, while no significant difference between the two groups was appreciated in the positioning of the femoral component in the coronal plane. Conclusions TKA using the accelerometer-based KA2 system was found to offer a high degree of accuracy in component alignment, and in particular, significantly improved tibial component alignment in comparison with conventional alignment methods in a Chinese population. However, no significant improvements were observed in neutral mechanical axis of the lower limb alignment and femoral component placement in the coronal plane.

Is Posterior Femoral Neck Cortex an Obstacle in Achieving Sagittal Plane Balance of Uncemented Straight Femoral Stem?

There is a paucity of the literature that aims to improve sagittal plane balance of femoral stem in hip arthroplasty. We have comparatively evaluated the effect of trimming the posterior cortex left in situ after femoral neck osteotomy and counter-clockwise rotation of starting awl with respect to their ability to achieve neutral alignment of femoral stem in sagittal plane. (1) Which of the two techniques under reference is more reliable in achieving a sagittal plane balance of the femoral stem in the femoral canal? (2) Does either of the two techniques have the potential to adversely affect other parameters for the optimum placement of femoral stem? This prospective study involved a total of 60 patients (age group of 18 to 60years) who underwent primary total hip arthroplasty (THA) through a standard posterolateral approach. They were randomized into groups (1) PNCT (n = 30): femoral canal preparation was done by posterior neck cortex trimming method; (2) CCRA (n = 30): femoral canal preparation was done by counter-clockwise rotation of starting awl. Postoperatively, radiographs and computed tomography were obtained and angle of femoral stem with the femoral canal in coronal and sagittal plane, femoral stem tip deviation in coronal and sagittal plane, anteversion of the femoral stem, duration of canal preparation and blood loss were analyzed between the two groups. Based on our results, there is a significantly better sagittal alignment of the femoral stem within the femoral canal, both in terms of angle of the femoral stem with the femoral canal (p < 0.001) and the deviation of the femoral stem tip from the center of the medullary canal (p < 0.001) when the posterior neck cortex was trimmed. Canal preparation by trimming the posterior neck cortex took a mean of 11.93min (range 8-15min) against the mean duration of 6.87min (range; 5min to 9min) in the other group (p < 0.001). Trimming the posterior femoral neck cortex after neck osteotomy results in better sagittal plane balance of uncemented straight femoral stem. III.

Thoracolumbar and Lumbopelvic Spinal Alignment During the Barbell Back Squat: A Comparison Between Men and Women.

Maintaining neutral spinal alignment is considered important when performing the barbell back squat exercise. Since male and female lifters may differ in injury location it is important to examine whether they differ in spinal alignment during the back squat. The study aimed to quantify the spinal alignment in the upper and lower lumbar spine during the barbell back squat exercise in male and female lifters. Secondary aims were to compare alignment during the back squat to standing habitual lumbar spine alignment and determine whether male and female lifters differ in these aspects. Observational, Cross-sectional. Competitive power- and weightlifters were recruited and performed three repetitions of the barbell back squat exercise using a load equivalent to 70% of their one-repetition maximum. Spinal alignment and range of motion were measured using inertial measurement units placed on the thoracic, lumbar and sacral spine. Data was presented descriptively and comparisons between men and women as well as spinal alignment in four different positions were done with a factorial repeated measures analysis of variance. Twenty-three (14 males, 9 females) were included. During execution of the squat, spinal alignment adjustments in the lumbar spine were made in all three planes of movement, compared to the start position, in both male and female lifters. Compared to their standing habitual posture, all lifters adjusted their upper lumbar spine to a less lordotic position when in the start position of the back squat (standing upright with the barbell on their back). Only male lifters assumed a less lordotic alignment in their lower lumbar spine in the start position compared their habitual posture. Adjustments of spinal alignment, predominantly in the sagittal plane, are made during execution of the back squat in both male and female lifters. Further, lifters adopt a less lordotic alignment with a heavy barbell on their upper back, more so in male than female lifters. In conclusion, it seems that spinal alignment changes noticeably during the barbell back squat. 3©The Author(s).

Neutral Mechanical Alignment and Prevalence of Constitutional Varus Knees Among the Saudi Population at King Saud University Medical City.

Background Various studies have described the restoration of the neutral mechanical alignment of the lower limb in total knee replacement (TKR) as a key factor of knee implant durability. Mechanical alignment of the knee requires that the tibial and femoral cuts are perpendicular to the mechanical axis of each bone in the coronal plane. Objectives The aim of this study is to investigate mechanical knee alignment and the prevalence of constitutional varus knee among the Saudi population at a single tertiary center with no history of musculoskeletal abnormalities. Methodology This is a retrospective cross-sectional study involving patients with no musculoskeletal abnormality who had their lower limb X-ray Centigram using the universal viewer zero footprint system made between 2015 and 2021. The study took place at King Saud University Medical City. The X-rays were obtained from patients' electronic medical records retrospectively. A total of 728 knees of 370 males and 358 females were included in this study. Results The results showed that 165 male knees (44.4%) and 218 female knees (60%) had constitutional varus alignment with the hip-knee-ankle (HKA) angle of ≤3° or less. The average HKA angle was smaller in males than in females: -3.69° versus -1.98°, respectively. Conclusion We have identified variables and factors that can help surgeons detect the constitutional varus on a full leg radiograph preoperativelyat the time of TKA, regardless of the osteoarthritic changes of the knee. We encourage the scientific community to look for causes and risk factors for developing constitutional varus.

Clinical and Radiological Outcomes of a Comparative Study of Anterior Cervical Decompression and Fusion with Partial Pediculotomy, Partial Vertebrotomy (PPPV) Posterior Endoscopic Cervical Decompression (PECD) for Cervical Foraminal Pathology.

Background and Objectives: The purpose was to compaSre medium-term clinical and radiological outcomes of Partial Pediculotomy, Partial Vertebrotomy (PPPV) Posterior Endoscopic Cervical Decompression (PECD) surgery versus Anterior Cervical Discectomy and Fusion (ACDF) for patients with cervical disc herniations and foraminal pathologies. Materials and Methods: A prospective registry of patients who had undergone either PPPV PECD surgery or ACDF surgery for cervical disc herniation or foraminal pathologies under a single fellowship-trained spine surgeon was performed. The baseline characteristics and operative details including complications were recorded for all included patients. The clinical outcomes evaluated include VAS, MJOA, motor score, and NDI and MacNab's score. The radiological parameters in neutral-measured facet length, facet area, disc height, C2-C7 angle, neck tilt angle, T1 slope and thoracic inlet angle were also evaluated. Results: A total of 55 patients (29 PPPV PECD, 26 ACDF) were included, with mean follow-up periods of 21.9 and 32.3 months, respectively. Each cohort was noted to have a single case of surgical complication. Statistically significant changes of facet area (49.05 ± 14.50%) and facet length (52.71 ± 15.11%) were noted in the PPPV PECD group. At neutral alignment of the neck on a lateral X-ray, compared to ACDF, PPPV PECD had a statistically significant change in neck tilt angle (-11.68 ± 17.35°) and T1 slope angle (-11.69 ± 19.58°). Whilst both PPPV PECD and ACDF had significant improvements in VAS, MJOA and NDI postoperatively, PPPV PECD was found to be superior across all above scores at various follow-up timepoints compared to its ACDF counterparts. Conclusions: PPPV PECD surgery achieved a satisfactory radiological correction of neck alignment and significantly improved clinical outcomes at medium-term follow-up for our cohort of patients, highlighting its feasibility in treating patients with cervical disc herniations and foraminal pathologies.

Gender-specific distribution of knee morphology according to CPAK and functional phenotype classification: analysis of 8739 osteoarthritic knees prior to total knee arthroplasty using artificial intelligence.

Osteoarthritis of the knee is commonly associated with malalignment of the lower limb. Recent classifications, as the Coronal Plane Alignment of the Knee (CPAK) and Functional Phenotype classification, describe the bony knee morphology in addition to the overall limb alignment. Data on distribution of these classifications is not sufficient in large populations. The aim of this study was to analyse the preoperative knee morphology with regard to the aforementioned classifications in long leg radiographs prior to total knee arthroplasty surgery using Artificial Intelligence. The cohort comprised 8739 preoperative long leg radiographs of 7456 patients of all total knee arthroplasty surgeries between 2009 and 2021 from our institutional database. The automated measurements were performed with the validated Artificial Intelligence software LAMA (ImageBiopsy Lab, Vienna) and included standardized axes and angles [hip-knee-ankle angle (HKA), mechanical lateral distal femur angle (mLDFA), mechanical medial proximal tibia angle (mMPTA), mechanical axis deviation (MAD), anatomic mechanic axis deviation (AMA) and joint line convergence angle (JLCA)]. CPAK and functional phenotype classifications were performed and all measurements were analysed for gender, age, and body mass index (BMI) within these subgroups. Varus alignment was more common in men (m: 2008, 68.5%; f: 2953, 50.8%) while neutral (m: 578, 19.7%; f: 1357, 23.4%) and valgus (m: 345, 11.8%; f: 1498, 25.8%) alignment was more common in women. The most common morphotypes according to CPAK classification were CPAK Type I (2454; 28.1%), Type II (2383; 27.3%), and Type III (1830; 20.9%). An apex proximal joint line (CPAK Type VII, VIII and IX) was only found in 1.3% of all cases (n = 121). In men, CPAK Type I (1136; 38.8%) and CPAK Type II (799; 27.3%) were the most common types and women were spread more equally between CPAK Type I (1318; 22.7%), Type II (1584; 27.3%) and Type III (1494; 25.7%) (p < 0.001). The most common combination of femur and tibia types was NEUmLDFA0°,NEUmMPTA0° (m: 514, 17.5%; f: 1004, 17.3%), but men showed femoral varus more often. Patients with a higher BMI showed a significantly lower age at surgery (R2 = 0.09, p < 0.001). There were significant differences between men and women for all radiographic parameters (p < 0.001). Distribution in knee morphology with gender-specific differences highlights the wide range in osteoarthritic knees, characterized by CPAK and phenotype classification and may influence future surgical planning. Level III.

Influence of Preoperative Sagittal Alignment on Functional Recovery in Operated Cases of Cervical Spondylotic Myelopathy.

Objective We examine the influence of preoperative cervical sagittal curvature (lordotic or nonlordotic) on the functional recovery of surgically managed cases of cervical spondylotic myelopathy (CSM). The impact of sagittal alignment on the functional improvement of operated CSM cases has not been thoroughly investigated. Materials and Methods We did retrospective analysis of consecutively operated cases of CSM from March 2019 to April 2021. Patients were grouped into two categories: lordotic curvature (with Cobb angle > 10 degrees) and nonlordotic curvature (including neutral [Cobb angle 0-10 degrees] and kyphotic [Cobb angle < 0 degrees]). Demographic data, and preoperative and postoperative functional outcome scores (modified Japanese Orthopaedic Association [mJOA] and Nurick grade) were analyzed for dependency on preoperative curvature, and correlations between outcomes and sagittal parameters were assessed. Results In the analysis of 124 cases, 63.1% (78 cases) were lordotic (mean Cobb angle of 23.57 ± 9.1 degrees; 11-50 degrees) and 36.9% (46 cases) were nonlordotic (mean Cobb angle of 0.89 ± 6.5 degrees; -11 to 10 degrees), 32 cases (24.6%) had neutral alignment, and 14 cases (12.3%) had kyphotic alignment. At the final follow-up, the mean change in mJOA score, Nurick grade, and functional recovery rate (mJOArr) were not significantly different between the lordotic and nonlordotic group. In the nonlordotic group, cases with anterior surgery had a significantly better mJOArr than those with posterior surgery ( p = 0.04), whereas there was similar improvement with either approach in lordotic cases. In the nonlordotic group, patients who gained lordosis (78.1%) had better recovery rates than those who had lost lordosis (21.9%). However, this difference was not statistically significant. Conclusion We report noninferiority of the functional outcome in the cases with preoperative nonlordotic alignment when compared with those with lordotic alignment. Further, nonlordotic patients who were approached anteriorly fared better than those approached posteriorly. Although increasing sagittal imbalance in nonlordotic spines portend toward higher preoperative disability, gain in lordosis in such cases may improve results. We recommend further studies with larger nonlordotic subjects to elucidate the impact of sagittal alignment on functional outcome.

Assessing the impact of critical risk factors on the development of musculoskeletal disorders: a structural equation modelling approach

Musculoskeletal Disorders (MSDs) have a significant impact on people’s lives as well as their workplaces, organizations, families, society, and national economy. Therefore, the main objective of this study is to investigate the impacts of different risk factors in developing MSD problems. Structural equation modelling has been used to examine the effects of different risk factors on developing MSD problems. Five hypotheses were developed for workplace, personal, biomechanical, psychosocial, and organisational risk factors to examine the positive relation with MSD problems generation. Results showed that biomechanical risk factors, including repetitive motion, vibration, force, posture, and deviation from neutral body alignment, have significant impacts on the development of MSD problems. Similar results were found for workplace, personal, psychosocial, and organisational risk factors. Therefore, either the single risk factor or collectively contributes significantly to MSD problems generation. Decision-makers can use this study to analyse the impacts of different factors on the generation of MSD problems within their industries or organizations. To the best of the author’s knowledge, this study is the first and foremost approach to determine the impacts of the critical risk factors on developing MSD problems through an organised and scientific approach.

Valgus alignment of the femoral component is associated with higher revision rates 10years after TKA.

Appropriate positioning and alignment of tibial and femoral component in primary total knee arthroplasty (TKA) are factors of major importance directly related to patient satisfaction and implant survival. Most literature works elaborate on overall post-operative alignment and its correlation to implant survival. However, less is known about the impact of individual component alignment. The purpose of this study was to investigate the effect of undercorrection of overall alignment as well as the effect of individual tibial and femoral component alignment on the post-operative failure rate after total knee arthroplasty. Clinical and radiographic data of primary TKA cases from 2002 to 2004, with a minimum of 10-year follow-up, were retrospectively reviewed. The pre- and post-operative hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured on weight-bearing, full-length antero-posterior lower limb radiographs. Statistical analysis was performed to establish the correlation between both overall and implant alignment and revision rate. In total, 379 primary TKA cases were evaluated. The mean time of follow-up was 12.9years (range 10.3-15.9years, SD = 1.8). Nine out of 379 cases were revised due to aseptic loosening; the mean time to revision was 5.5years (range 1.0-15.5years, SD = 4.6). Varus undercorrection of overall alignment was not associated with a higher rate of revision (p = 0.316). Post-operative valgus femoral alignment (mLDFA < 87°) contributed to a significant decreased prosthesis survival in contrast to neutral femoral alignment (revision rate valgus group: 10.7% and neutral group: 1.7%; p = 0.003). Post-operative tibial mechanical alignment was not identified as a significant predictor for implant survival (revision rate varus group: 2.9% and neutral group: 2.4%; p = 0.855). Primary TKA showed significantly higher revision rates when the femoral component was placed in > 3° of valgus (mLDFA < 87°). In contrast, postoperative overall residual varus alignment (HKA) and varus alignment of the tibial component were not related to higher revision rates at a minimum 10-year follow-up after TKA. These findings should be considered when choosing component position in individualised TKA. III.

Hallux Valgus Bunion Splint: Surgical Dressing Technique.

Hallux valgus is a common condition with a complex etiology resulting in numerous treatment options. Recurrence of the deformity can occur following correction. Surgical technique and possibly also postoperative care play a role in reducing recurrence rates. This article highlights a postoperative surgical dressing technique which allows for semirigid support during the immediate postoperative period. A wooden tongue depressor placed along the medial border of the hallux comprises the primary support for the dressing. The rigidity of the tongue depressor allows for the hallux to be drawn toward the depressor, encouraging neutral alignment of the hallux. Dressings are removed 2 weeks postoperatively, with new dressings applied in similar fashion and maintained in place until 6 weeks postoperatively. Based upon our observations, our surgical dressing technique provides sufficient support following hallux valgus correction surgery while being straightforward to replicate without the need for frequent dressing changes. The dressing materials are of negligible cost and are typically readily available. No associated wound complications have been observed. We present an easily replicable and affordable option for postoperative hallux valgus correction surgical dressings. Level V: Expert Opinion.

All-Inside Repair of Complex Posterior Horn Meniscus Tears

Background: Due to difficult-to-access location and complex tear patterns, the management of meniscus injuries in isolation and in conjunction with anterior cruciate ligament injury may be challenging. The aim of this video is to present techniques and tips that may help surgeons perform arthroscopic all-inside repair of complex meniscus tears. Indications: Indications for the presented repair techniques are young patients with high activity demands, symptomatic lateral and medial meniscus lesions, ligamentous knee instability, chondral changes grade 2 or less, neutral joint alignment, and body mass index below 35 kg/m2. Technique Description: High anterolateral, low anteromedial, and accessory anterolateral portals are used for the arthroscopic assessment of meniscus tear quality and pattern, and to ensure adequate access to the lesion. Horizontal mattress, vertical mattress, and cerclage sutures are passed using a range of all-inside devices to approximate tear edges with the aim of restoring native hoop stresses along the circumferential meniscus collagen fibers. Tear edges are abraded to enhance healing potential. Two separate cases and complex tear configurations are presented to illustrate these all-inside meniscus repair techniques. Results: Meniscus repair yields superior long-term outcomes compared with partial meniscectomy. Improvements in subjective knee function and lower rates of progression to long-term knee osteoarthritis are reported in patients treated with meniscus repair versus resection. Advantages of all-inside meniscus repair include the reduced risk of iatrogenic neurovascular lesions, decreased operative time, restoration of native contact surfaces, and repair without fixation of the menisci to the surrounding soft tissue. Discussion/Conclusion: Arthroscopic all-inside meniscus repair enables the safe and efficient management of complex meniscus tears in active patients with symptomatic meniscus pathology, and can be performed concurrent with knee ligament surgery. Consequently, all-inside meniscus repair techniques are a versatile addition to the toolkit of complex knee surgeons. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

MALALIGNMENT OF TOTAL ANKLE ARTHROPLASTY INCREASES PEAK CONTACT PRESSURE AND SHEAR STRESS ON THE BONE-IMPLANT INTERFACE

An increasingly used treatment for end-stage ankle osteoarthritis is total ankle replacement (TAR). However, implant loosening and subsidence are commonly reported complications, leading to relatively high TAR failure rates. Malalignment of the TAR has often been postulated as the main reason for the high incidence of these complications. It remains unclear to what extent malalignment of the TAR affects the stresses at the bone-implant interface. Therefore, this study aims to elucidate the effect of TAR malalignment on the contact stresses on the bone-implant interface, thereby gaining more understanding of the potential role of malalignment in TAR failure.FE models of the neutrally aligned as well as malaligned CCI Evolution TAR implant (Van Straten Medical) were developed. Separate models were developed for the tibial and talar segment, with the TAR components in neutral alignment and 5° and 10° varus, valgus, anterior and posterior malalignment, resulting in a total of 9 differently aligned TAR models. Loading conditions of the terminal stance phase of the gait cycle, when the force on the ankle joint is highest (5.2x body weight), were applied. Peak and mean contact pressure and shear stress at the bone-implant interface were analyzed. Also, stress distributions on the bone-implant interface were visualized.In the neutrally aligned tibial and talar TAR models, peak contact pressures of respectively 98.4 MPa and 68.2 MPa, and shear stresses of respectively 49.3 MPa and 39.0 MPa were found. TAR malalignment increases peak contact pressure and shear stress on the bone-implant interface. A maximum peak contact pressure of 177 MPa was found for the 10° valgus malaligned tibial component and the highest shear stress found was 98.5 MPa for the 10° posterior malaligned talar model.Upon TAR malalignment contact stresses increase substantially, suggesting that proper orientation of the TAR is needed to minimize peak stresses on the bone-implant interface. This is in line with previous studies, which state that malalignment considerably increases bone strains, micromotion, and internal TAR contact pressures, which might increase the risk of TAR failure. Further research is needed to investigate the relationship between increased contact stresses at the bone-implant interface and TAR failure.

660 Intraoperative O-C2 and O-EA Angular Measurements for Achieving Optimal Alignment During Posterior Fossa Decompression and Occipitocervical Fusion for Complex Chiari Malformation

INTRODUCTION: Excess flexion or extension during occipitocervical fusion (OCF) can lead to postoperative complications such as dysphagia and neck pain. Achieving neutral craniocervical alignment intraoperatively can be challenging in patients with Chiari malformation (CM) with craniocervical instability (CCI) undergoing posterior fossa decompression (PFD) and OCF because the head must be flexed for optimal PFD and subsequently extended to neutral for OCF. METHODS: We retrospectively reviewed patients with CM 1 and 1.5 who underwent PFD and OCF. Patient demographics, preoperative presentation, XR morphometrics, operative details, postoperative complications, and clinical outcomes were analyzed. RESULTS: Out of 39 patients (mean age 24.6 years, range 3-51, 76.9% female), 37 patients did not require revision surgery after PFD and OCF. In this non-revision cohort, O-C2a (13.5 ± 10.4° vs. 17.5 ± 10.1°, P = .047) and nPAS (10.9 ± 3.4 mm vs. 13.1 ± 4.8 mm, P = .007) increased significantly after surgery. In 2 patients who required revision due to postoperative dysphagia, these measurements acutely decreased after initial surgery (mean difference -16.6° in O-C2a and -12.8° in O-EAa), and revision surgery restored the morphometrics back to baseline. Applying these observations, we now intraoperatively measure these fluoroscopic morphometrics and ensure neutral craniocervical alignment using the Mayfield head clamp locking mechanism prior to hardware placement. CONCLUSIONS: Utilizing fluoroscopic morphometrics pre- and intra-operatively can guide surgeons in appropriate positioning during combined PFD and OCF. With neutral rotatory fixation, single-axis flexion/extension of the head during each stage of the surgery with the Mayfield head clamp locking mechanism facilitates positioning in conjunction with these fluoroscopic-based measurements.