Leg Alignment Research Articles

High variability exists in 3D leg alignment analysis, but underlying principles that might lead to agreement on a universal framework could be identified: A systematic review.

To (1) investigate the hypothesis that there is high variability in the reported methods to derive axes and joint orientations from three-dimensional (3D) bone models to (a) perform 3D knee-related leg alignment analysis and (b) define coordinate systems for the femur, tibia and leg and (2) identify underlying principles that might lead to agreement on a universal 3D leg alignment analysis framework. A systematic review of the literature between January 2006 and June 2024 was performed. Articles explicitly reporting methods to derive axes and joint orientations from CT-based 3D bone models for alignment parameters and/or coordinate systems of the femur, tibia and leg were included. Study characteristics and reported methods were extracted and presented as a qualitative synthesis. A total of 93 studies were included. There was high variability in the reported methods to derive axes and joint orientations from 3D bone models. Nevertheless, the reported methods could be categorized into four groups, and several underlying principles of the four groups could be identified. Furthermore, the definitions of femoral and tibial coordinate systems were most frequently based on the mechanical axis (femoral, 13/19 [68%]; tibial, 13/26 [50%]) and a central medial-lateral axis (femoral, 16/19 [84%]; tibial, 12/26 [46%]); no leg coordinate system was reported. Interestingly, of the included studies that reported on leg alignment parameters (76/93, 82%), only a minority reported expressing these in a complete coordinate system (25/76, 33%). There is high variability in 3D knee-related leg alignment analysis. Therefore, universal 3D reference values for alignment parameters cannot yet be defined, and comparison of alignment parameter values between different studies is impossible. However, several underlying principles to the reported methods were identified, which could serve to reach more agreement on a future universal 3D framework for leg alignment analysis. Level I (1).

Stress Distribution Patterns of the Femorotibial Joint After Medial Closing-Wedge Distal Femoral Varus Osteotomy: An Evaluation Using Computed Tomography Osteoabsorptiometry

Background: Distal femoral varus osteotomy (DFVO) is an established surgical procedure for addressing valgus malalignment across various knee conditions. However, the effect of DFVO on stress distribution within the femorotibial joint has not been explored through in vivo studies. Purpose: To (1) explore the distribution pattern of subchondral bone density across the proximal tibia in nonarthritic knees without arthritis and in those of patients with valgus knees, (2) assess changes in the pattern of bone density distribution in patients with valgus knees before and after medial closing-wedge (MCW) DFVO, and (3) determine the correlation between leg alignment and changes in bone density distribution. Study Design: Cohort study; Level of evidence, 3. Methods: The authors retrospectively analyzed clinical and radiographic data from 14 patients (14 knees; mean age, 44 years; 3 men, 11 women) treated with MCW-DFVO for lateral compartment osteoarthritis (OA) due to valgus malalignment, alongside a control group of 18 patients (18 knees; mean age, 21 years; 4 men, 14 women) without OA. The distribution patterns of subchondral bone density distribution on the femorotibial articular surface of the tibia were examined both preoperatively and >1 year postoperatively using computed tomography osteoabsorptiometry. Quantitative analyses were conducted on the locations and percentages of the high-density areas (HDAs) on the articular surface. The mean time between surgery and the postoperative radiograph and computed tomography absorptiometry imaging was 13.6 months (range, 11-19 months). The mean length of clinical follow-up was 28.7 months (range, 14-62 months) after surgery. Results: The mean proportion of HDA in the lateral compartment relative to the total HDA (lateral ratio) was significantly greater in the preoperative OA group (58.8%) compared with the control group (41.1%) (P < .001). After MCW-DFVO, the mean lateral ratio in the OA group notably declined to 45.3% (P < .001). The lateral ratio exhibited a significant correlation with the hip-knee-ankle angle in both the control (r = 0.630; P = .011) and OA (r = 0.537; P = .047) groups. Moreover, the alteration in the lateral ratio after MCW-DFVO showed a significant relationship with changes in the hip-knee-ankle angle (r = 0.742; P = .002) and the mechanical lateral distal femoral angle (r = −0.752; P = .002). Within the lateral compartment, HDAs in the 3 lateral regions of the 4 lateral subregions diminished after MCW-DFVO, whereas in the medial compartment, HDAs in the 3 lateral subregions saw an increase. Conclusion: The mean lateral ratio was significantly greater in the preoperative OA group compared with the control group. MCW-DFVO resulted in a redistribution of HDA from the lateral to the medial compartment of the proximal tibial articular surface. The extent of alignment correction after MCW-DFVO was closely linked to the shifts in HDA distribution, reflecting changes in stress distribution.

Osteochondroma of the Distal Tibia in an Adolescent: A Case Report

A 17-year-old male presented with a painful left ankle that had been worsening over the preceding 1 year. Clinical and radiographic inspection revealed marked bowing with a deformation of the fibula secondary to the laterally outgrowing bone lesion from the distal tibia proximal to the growth plate. MRI appearance suggestive of an osteochondroma of the lower extremity of the left tibia with signs of degeneration, It is surrounded by a cartilaginous cap, thickened in places, measuring 22 mm in maximum thickness. Although the radiographic characteristics of the lesion were indicative of osteochondroma, a typically asymptomatic and benign tumor that is usually identified as an incidental finding, the large size and symptoms associated with the lesion described in this article make it rather unusual. In this particular case, excessive bony outgrowth, pain, joint malposition, necessitated surgical intervention. The patient was successfully treated with resection of the tumor, after which gradual restoration of the alignment of the distal leg ensued without the need for fibular osteotomy. After more than 1 year of postoperative follow-up, neither radiographic nor clinical evidence of recurrence had been observed and the patient displayed a pain-free range of ankle motion without any physical limitations.

Analyzing Alignment Error in Tibial Tuberosity–Trochlear Groove Distance in Clinical Scans Using 2D and 3D Methods

Background: Tibial tuberosity–trochlear groove distance (TT-TG) is often used as a primary metric for surgical decision-making in the treatment of patellofemoral instability (PFI), particularly when considering tibial tubercle transfer. Although TT-TG has high interrater reliability, it is prone to measurement differences caused by the alignment of the patient's leg in a scanner gantry, potentially influencing surgical decision-making. Quantification of this error within the clinical literature remains limited. Purpose: To quantify and specify the error in TT-TG caused by leg-scanner alignment by using detailed topographical landmarks and 3-dimensional (3D) analysis of computed tomography scans of patients with PFI. Study Design: Controlled laboratory study. Methods: Three-dimensional models of knees with PFI were created from computed tomography scans and used to identify TT-TG landmarks. TT-TG was measured using the established 2-dimensional (2D) and 3D methods. A model to estimate the differences between these 2 methods was created, and the orientation of the patients’ legs in relation to scanner longitudinal axis was measured to validate this model via linear regression. Interrater reliability was calculated via intraclass correlation coefficients (ICC). Results: A total of 44 knees of patients with PFI were analyzed. Differences between the 2D and 3D methods ranged from -4.0 to 14.7 mm (mean ± SD, 2.7 ± 4.1 mm) with a root mean square difference of 4.8 mm. The TT-TG distance of the 2D method (19.8 ± 7.2 mm) was significantly (P = .045) longer than that of the 3D method (17.1 ± 4.9 mm). The variance of the 2D method was significantly larger than that of the 3D method. In total, 13 (29.5%) of the knees had a difference of >5 mm between 2D and 3D TT-TG. The estimation model had an adjusted r2 value of 1.00 and a resulting root mean square difference of 0.21 mm. 3D TT-TGs interrater reliability was good to excellent (ICC, 0.94 [95 CI%, 0.81-0.98]). Conclusion: 3D TT-TG can be used to correct scanner-leg alignment errors, some of which are substantial when using only 2D TT-TG measurements. Clinical Relevance: The findings in this study suggest a need for caution and awareness of the potential effects of differences in alignment of the axes of the leg and scanner when using purely 2D TT-TG as a basis for surgical planning.

Revision Surgery due to Patient Dissatisfaction with Remaining Valgus leg Alignment after Kinematically Aligned Total Knee Arthroplasty: A Case Report

BACKGROUND: The kinematic alignment (KA) technique aims to achieve true resurfacing of the knee joint and recreate prearthritic anatomy while preserving soft tissues. However, it remains uncertain whether all prearthritic anatomies are biomechanically equivalent and if KA is suitable for cases with extreme anatomical variations. CASE PRESENTATION: The case of a 75-year-old female patient with a moderate valgus deformity who underwent kinematically aligned total knee arthroplasty (TKA) was reported. The patient required early revision surgery due to persistent pain in the medial collateral ligament area and dissatisfaction with the postoperative leg alignment. CONCLUSION: There is a paucity of studies addressing the outcomes of kinematically aligned TKA in patients with valgus knees. Concerns persist regarding the suitability of unrestricted KA for all anatomical variations, particularly extreme ones. This case underscores the importance of considering restricted KA as a potentially safer alternative. In addition, patient perception of limb alignment and appearance significantly impacts the success of total knee arthroplasty, particularly in cases with valgus deformities.

Experimental Study on the Effect of Pilates Training on the Correction of O-shaped Legs in College Students

This study investigates the corrective effects of Pilates training on O-shaped legs among university students. Thirty-two students from the University of Malaya participated in a 10-week Pilates program. The study employed a quantitative approach with pre- and post-intervention measurements to assess changes in knee gap and muscle strength. Results indicated significant improvements in both natural and active knee gaps, suggesting that Pilates effectively strengthens the muscles responsible for leg alignment. The study also found gender and location differences, with males and urban students showing greater knee gap reductions. The sustainability of these improvements was confirmed, with no significant regression observed two weeks post-intervention. This research highlights the potential of Pilates as a non-invasive intervention for postural and musculoskeletal issues, particularly among young adults prone to such problems due to sedentary lifestyles. These findings have significant implications for physical education and rehabilitation, advocating for the integration of Pilates into training regimens to enhance overall physical well-being. Future research should explore the long-term effects and broader applications of Pilates.

Effect of Stem Design and Positioning on the Leg Axis after Total Hip Arthroplasty: A Secondary Analysis.

Background/Objectives: Various parameters, like femoral offset and leg length, are associated with good patient outcomes after total hip arthroplasty. In this prospective study, the effects of stem design, its placement in the proximal femur and the resulting femoral offset on the total leg axis were investigated. Methods: The 27 patients included in this study received biplanar radiography (EOS®, EOS Imaging) with 3D reconstruction using sterEOS® both preoperatively and postoperatively. For all leg alignment parameters obtained from the 3D reconstruction and from measurements using mediCAD, the deltas between the postoperative and preoperative values were determined. Patients were divided into those who received a short-stem prosthesis and those who received a straight-stem prosthesis. Results: The change in femoral offset with the implantation of a short-stem prosthesis was significantly greater than that with the implantation of a straight-stem prosthesis (11.4 ± 5.9 vs. 4.6 ± 7.4 mm, p = 0.014). Compared with the straight-stem implantation, short-stem implantation caused a significantly greater increase in the varus orientation of the leg (-1.4 ± 0.9 vs. -0.4 ± 1.4°, p = 0.048). There was no significant difference in the positioning of the short-stem prosthesis compared to the straight-stem prosthesis in the proximal femur (3.6 ± 3.1 vs. 2.6 ± 1.9°, p = 0.317). Conclusions: These findings substantiate the impact of prosthesis design on offset and leg alignment. The implantation of short-stems is more variable and requires precise planning. Intraoperative non-physiological offset changes and varus deviation of the leg axis should be avoided. Trial registration: This study was retrospectively registered with the German Clinical Trials Register (DRKS) under the number DRKS00015053 on the 1 August 2018.

Comparison of hip abductors’ strength and 2D frontal plane projection angle during two functional tests, in females with and without patellofemoral pain

IntroductionHip abductors eccentrically maintain leg alignment during weight-bearing exercises. Hip abductors' weakness may be a significant aspect to take into account in the conservative management of Patellofemoral Pain (PFP). The aim of the study was to compare hip abductors’ eccentric strength and hip kinematics during two functional tests, in female subjects with PFP. MethodIn a cross-sectional study using convenience sampling, isokinetic Isokinetic unilateral eccentric hip abductors’ mean peak moment (MPM) at 60°/sec and Frontal Plane Projection Angle (FPPA) during Single-Leg Squat (SLS) and Single-Leg Landing (SLL) tests, were assessed in 17 asymptomatic individuals and 19 PFP patients. ResultsThe FPPA during SLL (p = 0.771) and SLS (p = 0.587), as well as the isokinetic values of the eccentric adductors' MPM at 60°/sec (p = 0.769), did not differ between the groups. The isokinetic values and the SLL (r = −0.009 to p = 0.970) and SLS (r = −0.002 to p = 0.993) in the PFP group and the control group (SLS r = 0.160 to p = 0.540) did not show any statistically significant relationships. ConclusionPFP and asymmetry in hip abduction strength are not substantially correlated. It is necessary to conduct more research to comprehend how these impairments interact and to find out if there are patient subgroups with PFP.

Paper 15: Survivorship of 157 Arthroscopic Meniscal Allograft Transplants Using Bone Fixation at Mean 7 Years and Prognostic Factors Analysis

Objectives: Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration &amp; Joint Preservation Society (ICRS) grade. The purpose of this study was to determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure. Methods: Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (International Cartilage Regeneration &amp; Joint Preservation Society [ICRS] grade and Kellgren and Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs), Lysholm score, Knee Disability and Osteoarthritis Outcome Score (KOOS) including subscores, International Knee Documentation Committee (IKDC) score, and visual analog score (VAS) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty (TKA). Anatomic failure was considered a tear covering &gt;20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed utilizing the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure. Results: A total of 157 knees met inclusion criteria (Table 1). After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as anatomic failure, and 13 patients (8.3%) suffered from subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (HR 4.55; 95% CI 1.46-14.17; p=0.009) and anatomic failure (HR 3.05; 95% CI 1.34-6.92; p=0.008). Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR 3.41; 95% CI 1.05-11.01; p=0.04) and anatomic failure (HR 3.04; 95% CI 1.31-7.11; p=0.01) (Table 2). There were no differences in outcomes between medial and lateral MAT. High-grade cartilage damage (defined as ICRS grades 3 and 4) preoperatively (HR 10.67; 95% CI 1.037-109.768; p=0.046), patients age over 25 (HR 5.44; 95% CI 0.120-246.070; p=0.384), and a body mass index &gt;30 (HR 2.24; 95% CI 0.748-6.705; p=0.149) were associated with subjective failure. Considering the entire study population, PROMs including KOOS and IKDC were significantly improved at final follow-up compared to preoperative scores across all measurements (p&lt;0.005). Conclusions: MAT showed good-to-excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent osteochondral allograft transplantation are at higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest MAT has a lasting beneficial effect both as in isolation and in complex cases with one or more concurrent procedures.

Trochlea morphology demonstrates variability but no gender difference in osteoarthritic patients undergoing total knee arthroplasty

BackgroundIn recent years, coronal lower leg alignment has received significant attention. Two classifications recently described the variability in both femoral and tibial morphology, resulting in differing native lower limb alignment.The native trochlea and the variability in morphology has received less attention. MethodsThis is a prospective cohort study of 200 patients undergoing robotically assisted TKA. Preoperative transverse CT scans were used to determine the posterior condylar axis (PCA), transepicondylar axis (TEA), lateral trochlear inclination (LTI), the sulcus angle (SA) and the anterior trochlear line (ATL). Outliers were defined as values > 1.5 IQR from median value. Trochlea dysplasia was defined as LTI < 12°. Gender differences were compared. ResultsIn total, 99 patients were female (49.4%). SA had a median of 137.0° (IQR 12°), ATL 4° (IQR 4), LTI 18° (IQR 7°). Median TEA-PCA was 5° external (IQR 3°). There were 5.0% outliers in SA, 3.0% of outliers in ATL, 3.5% outliers in LTI and 4.5% outliers in the TEA-PCA. Trochlear dysplasia was present in 11.5% of the measurements. There was no difference in any of the angles between the genders. ConclusionThe present study demonstrates no difference in trochlea morphology between the genders, rather a significant number of overall outliers in trochlear morphology. Larger cohorts but also, more investigations, are needed to better understand the trochlear morphology of patients undergoing total knee arthroplasty. The personalized alignment strategies and implants need to account for this variability in the population.

Neutral to slightly undercorrected mechanical leg alignment provides superior long-term results in patients undergoing matrix-associated autologous chondrocyte implantation.

The aim of this study was to evaluate the role of leg alignment on long-term clinical outcomeafter matrix-associated autologous chondrocyte implantation (M-ACI) and to define an individualized target range to optimize clinical outcome. The present study examined patients who underwent M-ACI of the femoral condyle. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) were used to assess the results. Clinical outcomes were related to Patient Acceptable Symptomatic State (PASS). For intra- and interobserver reliability of mechanical tibiofemoral angle, mechanical medial proximal tibial angleand mechanical lateral distal femoral angle, we calculated intraclass correlation coefficientsusing a two-way mixed model with absolute agreement. A regression model and receiver-operating characteristics curve were used to identify an individual range of alignment where a favourable clinical outcome could be expected in the long term. Additional osteotomy was performed in 50% of patients with similar clinical outcomes as physiologically aligned patients (p > 0.05). The curve-fitting regression model identified a target range of -2.5° valgus to 4.5° varus for ideal postoperative alignment (R2 = 0.12, p = 0.01). Patients within this range were more likely to achieve PASS (70% vs. 27%, p = 0.001). In medially treated defects, a refined range of -2.5° valgus to 4° varus alignment was found (R2 = 0.15, p = 0.01). These patients were more likely to achieve PASS (67% vs. 30%, p = 0.01) and showed favourable postoperative KOOS and MOCART scores (p = 0.02). Patients with lateral defects were more likely to achieve PASS within a range of -2° valgus and 0.5° varus (90% vs. 45%, p = 0.03) and showed favourable postoperative KOOS and MOCART scores (p = not significant). An individual range of leg alignment-whether achieved by osteotomy or physiologic alignment-should be respected in M-ACI treatment. A neutral to slightly undercorrected alignment favours the postoperative outcome after M-ACI. When planning surgery for patients with focal cartilage defects of the femoral condyle, these ranges should be recognized as critical factors. Level III.

Current concept: personalized alignment total knee arthroplasty as a contrast to classical mechanical alignment total knee arthroplasty

Mechanical alignment (MA) total knee arthroplasty (TKA), with neutral leg alignment, mechanical component alignment, and parallel gaps, has achieved good long-term survival. Patient satisfaction, however, is not always perfect. In contrast to the MA, which aims for an ideal goal for all patients, an alternative has been proposed: kinematic alignment (KA)-TKA. In KA, the articular surface is replicated using components aligning with the three kinematic axes. KA-TKA has been gaining popularity, and in addition to the true or calipered KA, various derivatives, such as restricted KA, soft-tissue respecting KA, and functional alignments, have been introduced. Moreover, the functional approach encompasses several sub-approaches. This somewhat complicated scenario has led to some confusion. Therefore, the terminology needs to be re-organized. The term “personalized alignment (PA)” has been used in contrast to the MA approach, including all approaches other than MA. The term “PA-TKA” should be used comprehensively instead of KA and it represents the recent trends in distinct and unique consideration of each individual case. In addition to a comparison between MA and KA, we suggest that evaluation should be conducted to decide which approach is the best for an individual patient within the “personalized alignment” concept.

DOES GAIT LAB ASSESSMENT ASSIST IN DECISION MAKING IN PAEDIATRIC LIMB RECONSTRUCTION SURGERY?

IntroductionLimb deformity is usually assessed clinically assisted by long leg alignment radiographs and further imaging modalities (MRI and CT). Often decisions are made based on static imaging and simple gait interpretation in clinic. We have assessed the value of gait lab analysis in surgical decision making comparing surgical planning pre and post gait lab assessment.Materials &amp; MethodsPatients were identified from the local limb reconstruction database. Patients were reviewed in the outpatient clinic and long leg alignment radiographs and a CT rotational limb profile were performed. A surgical plan was formulated and documented. All patients then underwent a formal gait lab analysis. The gait lab recommendations were then compared to the initial plan.ResultsTwelve patients (8 female) with mean age of 14 (range 12–16) were identified. Nine were developmental torsional malalignments, one arthrogryposis, one hemiparesis secondary to spinal tumour resection and one syndromic limb deficiency. The gait lab recommended conservative management in four patients and agreed with eight surgical plans with one osteotomy level changing.Five patients are post-operative: two bilateral distal tibial osteotomies, two de-rotational femoral osteotomy with de-rotational tibial osteotomies and one bilateral femoral de-rotational osteotomies.ConclusionsLimb deformity correction is major surgery with long rehabilitation and recovery period. Gait lab analysis can identify who would benefit from conservative management rather than surgery with our study showing changes to surgical planning in one third of patients. The gait lab analysis helps to identify patients with functional and neuromuscular imbalances where correcting the bony anatomy may not actually benefit the patient.

GUIDED GROWTH SURGERY FOR TREATMENT OF PATELLAR INSTABILITY IN GENU VALGUM

IntroductionGenu valgum is a common presentation in paediatric patients with congenital limb deformities. The aim of this study is to assess the outcome of guided growth surgery in paediatric patients referred via our physiotherapy pathway with isolated genu valgum and associated patellar instability.Materials &amp; MethodsPatients were identified from our prospective patellar instability database. Inclusion criteria was acquired or congenital genu valgum associated with patellar instability in skeletally immature patients. The mechanical lateral-distal femoral angle was assessed on long leg alignment radiographs (mLDFA &lt;85 degrees). Surgical treatment was the placement of a guided growth plate (PediPlate, OrthoPediatrics, USA) on the medial distal femoral physis (hemi-epiphysiodesis). KOOS-child scores were collected pre-operatively and post-operatively (minimum at 6 months).ResultsEleven patients (seven female) with mean age of 12(range 5–15) were identified. Five patients had congenital talipes equinovarus(CTEV), one fibular hemimelia, one di-George syndrome, one septic growth arrest and three had idiopathic genu valgum. Pre- and post-operative KOOS-child scores showed overall improvement: 58(range 36–68) to 88(65–99) and knee symptoms subscores: 64(43–71) to 96(68–100) p&lt;0.01, t-test.Mean follow-up was 10 months (range 3–23). No subsequent dislocations/subluxations occurred during follow-up.ConclusionsGuided growth surgery is an effective way of treating symptomatic patellar instability in skeletally immature patients with genu valgum in the absence of other structural pathology. It was most common in our cohort in patients with unilateral CTEV. We would recommend to screen syndromic and congenital limb deformity patients for patellar instability symptoms in the presence of genu valgum.

Multicentric development and validation of a multi-scale and multi-task deep learning model for comprehensive lower extremity alignment analysis

Osteoarthritis of the knee, a widespread cause of knee disability, is commonly treated in orthopedics due to its rising prevalence. Lower extremity misalignment, pivotal in knee injury etiology and management, necessitates comprehensive mechanical alignment evaluation via frequently-requested weight-bearing long leg radiographs (LLR). Despite LLR’s routine use, current analysis techniques are error-prone and time-consuming. To address this, we conducted a multicentric study to develop and validate a deep learning (DL) model for fully automated leg alignment assessment on anterior–posterior LLR, targeting enhanced reliability and efficiency. The DL model, developed using 594 patients’ LLR and a 60%/10%/30% data split for training, validation, and testing, executed alignment analyses via a multi-step process, employing a detection network and nine specialized networks. It was designed to assess all vital anatomical and mechanical parameters for standard clinical leg deformity analysis and preoperative planning. Accuracy, reliability, and assessment duration were compared with three specialized orthopedic surgeons across two distinct institutional datasets (136 and 143 radiographs). The algorithm exhibited equivalent performance to the surgeons in terms of alignment accuracy (DL: 0.21 ± 0.18°to 1.06 ± 1.3°vs. OS: 0.21 ± 0.16°to 1.72 ± 1.96°), interrater reliability (ICC DL: 0.90 ± 0.05 to 1.0 ± 0.0 vs. ICC OS: 0.90 ± 0.03 to 1.0 ± 0.0), and clinically acceptable accuracy (DL: 53.9%–100% vs OS 30.8%–100%). Further, automated analysis significantly reduced analysis time compared to manual annotation (DL: 22 ± 0.6 s vs. OS; 101.7 ± 7 s, p ≤ 0.01). By demonstrating that our algorithm not only matches the precision of expert surgeons but also significantly outpaces them in both speed and consistency of measurements, our research underscores a pivotal advancement in harnessing AI to enhance clinical efficiency and decision-making in orthopaedics.

Preoperative Arithmetic Hip-Knee-Ankle Angle as a Predictor of Postoperative Leg Alignment in Medial Oxford Unicompartmental Knee Arthroplasty.

Introduction This study aimed to evaluate whether the arithmetic hip-knee-ankle angle (aHKA) can be used to predict the postoperative HKA. Methods This study included 248 knees in 166 patients who underwent Oxford unicompartmental knee arthroplasty (UKA) between February 2021 and November 2022. Through preoperative and postoperative long-leg radiography, the medial proximal tibial angle (MPTA) and the lateral distal femoral angle (LDFA) were expressed as the deviation from the perpendicular line to the mechanical axes, and the mechanical HKA (mHKA) was defined as the angle between the femoral and tibial mechanical axes. Using the MPTA and LDFA, the arithmetic HKA (aHKA; MPTA + LDFA) and the joint line obliquity (JLO; MPTA - LDFA) were calculated, and the preoperative and postoperative values were compared. Results The preoperative aHKA and the postoperative mHKA values were similar (-0.38° ± 2.96°) and significantly smaller than the difference between the preoperative and postoperative mHKAs (4.58° ± 3.60°, P < 0.05). Meanwhile, the MPTA tended to be varus, and the LDFA tended to be valgus. Eventually, the JLO inclined more medially from -6.33° ± 3.42° preoperatively to -8.97° ± 3.92° postoperatively, representing a significant difference (P < 0.05). Conclusion The preoperative aHKA was similar to the postoperative mHKA. Therefore, it can be regarded as a predictor of postoperative leg alignment after Oxford UKA. Meanwhile, there was a medial incline of the joint line. Further investigation is required to evaluate the effect of such a joint line alteration.

Survivorship of 157 Arthroscopic Meniscal Allograft Transplants Using Bone Fixation at a Mean of 7 Years and Prognostic Factors Analysis

Background: Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration & Joint Preservation Society (ICRS) grade. Purpose: To determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure. Study Design: Case-control study; Level of evidence, 3. Methods: Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (ICRS grade and Kellgren-Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs) (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale [VAS] score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty. Anatomic failure was considered a tear covering >20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed using the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure. Results: A total of 157 knees met inclusion criteria. After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as having experienced anatomic failure, and 13 (8.3%) patients experienced subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (hazard ratio [HR], 4.55; 95% CI, 1.46-14.17; P = .009) and anatomic (HR, 3.05; 95% CI, 1.34-6.92; P = .008) failure. Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR, 3.41; 95% CI, 1.05-11.01; P = .04) and anatomic (HR, 3.04; 95% CI, 1.31-7.11; P = .01) failure. High-grade cartilage damage preoperatively (HR, 10.67; 95% CI, 1.037-109.768; P = .046), patient age >25 years (HR, 5.44; 95% CI, 0.120-246.070; P = .384), and a body mass index >30 (HR, 2.24; 95% CI, 0.748-6.705; P = .149) were associated with subjective failure. PROMs including KOOS and IKDC were significantly improved at final follow-up compared with preoperative scores across all measurements (P < .005). Conclusion: MAT showed good to excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent OCA transplantation are at a higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest that MAT has a lasting beneficial effect both in isolation and in complex cases with ≥1 concurrent procedures.

Osteochondritis Dissecans of the Knee Associated With Mechanical Overload

Background: Osteochondritis dissecans (OCD) of the knee is a rare but potentially incapacitating disorder in which subchondral bone detaches, leading to an osteochondral fragment that can become unstable and progress into a loose body. The exact cause is unknown, although several biological and mechanical factors have been described. Purpose: To provide insight into epidemiological data of a large cohort of patients affected by OCD of the knee and to identify potential factors contributing to the cause of this disorder. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 236 patients (259 knees) affected by OCD were included in our Knee Registry (2005-2022) and retrospectively analyzed. Patient characteristics were extracted from the medical records. Location and International Cartilage Regeneration & Joint Preservation Society grade (1-4) of OCD were assessed using magnetic resonance imaging. If available, a full-leg standing radiograph was used to assess alignment. Additionally, a statistical scoring system for instability risk was created. Results: A total of 263 OCD lesions were identified in 259 knees, 66.2% on the medial femoral condyle (MFC), 26.6% on the lateral femoral condyle (LFC), 3.8% on the trochlea, 2.7% on the patella, and 0.8% on the lateral tibia plateau. Male patients made up 57.6% of the sample, which had a mean age of 21.8 years. A very high percentage of patients (77.1%; n = 182) practiced sports, of whom 67.6% (n = 123) were engaged in high-impact sports. The location of the OCD lesions and the leg alignment (n = 110) were significantly correlated: MFC lesions were associated with more varus than valgus alignment (47.5% vs 11.3%) and patients with LFC lesions had more valgus than varus alignment (46.7% vs 20.0%; P = .002). Based on age, smoking, sports activity, and preceding trauma, a multivariable scoring system (0-11 points) was created. An increased risk of lesion instability was associated with an increased score: 29.0% at 0 points and 97.0% at 11 points. Conclusion: This study provides detailed epidemiological data for 236 patients affected by OCD of the knee. Older age, smoking, inactivity, and preceding trauma were predictive for instability of OCD lesions. There was an association between OCD of the MFC and varus malalignment and between OCD of the LFC and valgus malalignment. This finding, in combination with the high percentage of patients practicing high-impact sports, suggests an important role for mechanical overload in the pathogenesis of OCD.

Editorial Comment on the Article by A.N. Tsed et al. “Total Knee Arthroplasty in Hemodialysis Patients: Routine or Complex Surgery?”

Severe comorbidities, like chronic kidney disease, strongly associated with higher risk of complications after total knee arthroplasty. Therefore hemodialysis patients need specific pre-operative as well as peri-operative management, including proper analgesic, antibacterial and thromboembolic pharmacological prophylaxis. Nevertheless the technical issues that surgeon has to solve in achieving proper leg alignment, knee stability and range of motion does not differ from other complex knee primary cases when revision implants and instruments are essential part of surgical requisite.

Enhancing Precision and Efficiency in Knee Arthroplasty: A Comparative Analysis of Computer-Assisted Measurements with a Novel Software Tool versus Manual Measurements for Lower Leg Geometry.

(1) Background: The aim of this prospective study was to evaluate measurement software in comparison with manual measurements using inter-observer and intra-observer variability on radiographs in the preoperative planning of total knee arthroplasty. (2) Methods: Two independent observers retrospectively measured the mechanical lateral proximal femoral angle (mLPFA), the mechanical lateral distal femoral angle (mLDFA), the joint line convergence angle (JLCA), the mechanical medial proximal tibial angle (mMPTA), the mechanical lateral distal tibial angle (mLDTA), the hip-knee angle or mechanical tibial-femoral axis angle (HKA), and the anatomical-mechanical angle (AMA) on 55 long-leg anteroposterior radiographs manually twice, followed by measurements using dedicated software. Variability between manual and computer-aided planning was assessed, and all measurements were performed a second time after 14 days in order to assess intra-observer variability. (3) Results: Concerning intra-observer variability, no statistically significant difference was observed regarding the software-based measurements. However, significant differences were noted concerning intra-observer variability when measuring the mLDFA and AMA manually. Testing for statistical significance regarding variability between manual and software-based measurements showed that the values varied strongly between manual and computer-aided measurements. Statistically significant differences were detected for mLPFA, mLDFA, mMPTA, and mLPTA on day 1, and mLPFA, mMPTA, and mLPTA on day 15, respectively. (4) Conclusions: Preoperative planning of leg axis angles and alignment using planning software showed less inter- and intra-observer variability in contrast to manual measurements, and results differed with respect to manual planning. We believe that the planning software is more reliable and faster, and we would recommend its use in clinical settings.