Studies on patients have shown that normal anatomic motion is often not achieved with current total knee arthroplasty (TKA) designs. The purpose of this study was to determine whether anatomic motion could be restored using a design where intercondylar guiding surfaces were positioned between the medial and lateral femoral condyles. A crouching machine was constructed, which included simulations of the collateral ligaments, the quadriceps mechanism, the hamstrings, and the gastrocnemius. Medial pivot, medially congruent, ultracongruent, and replica intercondylar TKAs were designed and 3-dimensionally printed. The femoral-tibial kinematics were measured by determining lateral and medial contacts, as the knee underwent flexion and extension from 12 to 130°. The replica intercondylar design showed an almost constant position of the medial contact, with a progressive posterior displacement laterally during flexion. In contrast, the other designs showed nearly parallel motion with minimal variation in contact location. It was concluded that intercondylar guiding surfaces could produce anatomical motion in a TKA where the cruciate ligaments were resected.

Bone Flaps for Structural Reconstruction of the Lower Extremity.

Intra-operative femoral condyle fractures during primary total knee arthroplasty: Incidence, risk patterns, and early outcomes in an Asian cohort.

The impact of preoperative rehabilitation on bone mineral density (BMD) and tendon-bone healing in anterior cruciate ligament reconstruction (ACLR) patients is unknown. A total of 53 ACL rupture patients were randomized into 2 groups (Control Group [CON, n = 27] and Exercise rehabilitation group [ER, n = 26]). The CON received conventional treatment, and the ER group received 6-week exercise on this basis. Subsequently, both groups underwent ACLR. At baseline, after 3, 6 and 12 months post-ACLR, the knee BMD, magnetic resonance imaging, and physical function were measured. The BMD of lateral femur condyle (LFC) in ER group was higher than CON group at 3 and 6 months post-ACLR (p = 0.004, 0.01). The signal/noise quotient (SNQ) of proximal and distal segments in ER group were lower than CON group at 6 and 12 months post-ACLR (p = 0.02, 0.03). The medial femoral condyle cartilage thickness in ER group was begun thicker than CON group at 3 months post-ACLR (p = 0.04). At 6 months post-ACLR, the relative peak torque of the quads and hamstrings, the balance composite score, the Lysholm and IKDC scores in the ER group were better than CON group (Quads p = 0.02; Hamstrings p = 0.01; balance p < 0.001; Lysholm p < 0.001; IKDC p < 0.001). The difference value of BMD from baseline to 3 months post-ACLR in medial femoral condyles (MFC) exhibited positive correlations with 6 and 12 months post-ACLR within distal autograft SNQ (p = 0.025; 0.011). ACLR patients who undergo preoperative rehabilitation can effectively delay the decline of BMD in the LFC, enhance the tendon-bone healing, improve the knee articular cartilage thickness and advance the physical function. The less the early BMD of MFC loss in early postoperative, the better the later tendon-bone healing within or near the tibial tunnel. PRS, NCT05924178. Registered 28 May 2023, www. gov.

Mechanical overloading is a key risk factor for knee osteoarthritis (OA), yet its compartment-specific effects on the mechanobiology of the osteochondral unit and its interplay with synovial inflammation remain insufficiently defined. Here, multiscale imaging of clinical specimens is applied to uncover how mechanical and inflammatory cues shape the osteochondral unit in knee OA. Medial and lateral femoral condyles from patients with primary OA and secondary OA due to rheumatoid arthritis (RA), spanning varus to valgus alignment, were analyzed. A comprehensive multiscale imaging pipeline, including micro-computed tomography, cartilage- and bone-specific histomorphometry, quantitative backscattered electron imaging, and osteocyte lacunocanalicular network analysis, is integrated with targeted proteomic profiling of synovial fluid. Mechanical alignment is strongly associated with compartment-specific cartilage degeneration and subchondral bone adaptation in OA, as reflected by robust correlations between loading and OARSI score, subchondral bone thickness, bone formation, and osteocyte lacunocanalicular network parameters. Notably, the medial compartment exhibits substantially greater susceptibility to mechanically induced osteochondral remodeling than the lateral compartment. In contrast, these structure-function relationships are attenuated in RA. Collectively, these findings indicate that osteochondral remodeling in knee OA is predominantly associated with mechanical loading and reveal disease- and compartment-specific patterns in the balance between mechanical and inflammatory contributions, supporting a more tailored approach to treating knee arthropathies by prioritizing biomechanical or anti-inflammatory strategies according to disease context and compartmental involvement. STATEMENT OF SIGNIFICANCE: There remains ongoing debate regarding the extent to which osteoarthritis (OA) is a mechanical disease. The investigation of leg axis deviations (i.e., mechanical alignment) provides an ideal model to address this question. Here, we present a comprehensive multiscale characterization of the osteochondral unit in knee OA, integrating clinical imaging, micro-CT, histomorphometry, quantitative backscattered electron imaging, and targeted synovial proteomics. Mechanical alignment emerged as the predominant factor associated with cartilage degeneration, pathological subchondral bone formation, and osteocyte lacunocanalicular network alterations. In contrast, synovial TNF-α independently predicted cartilage degeneration in an inflammatory OA subtype secondary to rheumatoid arthritis. These findings reveal disease- and compartment-specific patterns and support a tailored approach in which biomechanical and biological strategies are prioritized according to context.

Full-length standing lower limb radiographs are commonly used to measure limb length and femoral and tibial segmental lengths. The purpose of the study was to compare the differences in length measurements using 3 methods. We retrospectively reviewed preoperative full-length standing radiographs of skeletally immature patients with limb length discrepancy (LLD) scheduled for isolated epiphysiodesis of the proximal tibia and/or distal femur between 2012 and 2024 at a single center. Method 1 (True length) measured the longitudinal length from the top of the femoral head to the distal edge of the medial femoral condyle for the femoral segment, and from the distal edge of the medial femoral condyle to the center of the distal tibial plafond for the tibial segment. In method 2 (Apparent length), segmental height was measured as the vertical distance between horizontal reference lines drawn tangential to the top of the femoral head, the bottom of the medial condyle, and the distal tibial plafond. In method 3, functional LLD was measured based on the difference in femoral head height. Bland-Altman plots were used for measurement agreement analysis. Thirty-seven patients (16 boys, 43%) with a mean age of 13±1.5 years underwent epiphysiodesis for LLD. The mean absolute difference between methods 1 and 2 in the measurement of total limb length, femoral and tibial segmental lengths was 0.5mm, 1.5mm, and 1mm, respectively (P<0.0001). True Length (Method 1) slightly overestimated the length compared with Apparent Length (Method 2). LLD measured with methods 1 and 2 was similar to method 3 (P>0.05). The subtle differences between the methods correlated with coronal plan limb alignment. The 3 radiographic LLD measurement methods were comparable. The subtle variability in measurement values correlated with lower limb angular deformity, which highlights the importance of considering coronal plane deformity when interpreting radiographic measurements for LLD. Consistent use of a single measurement technique is important to avoid subtle variability in LLD estimation, especially in the presence of angular deformities. Level III.

The laryngotracheal junction (LTJ) is a functionally critical zone, due to its narrow anatomy, complex airflow dynamics, and proximity to the glottis and cricoid cartilage. Extensive stenoses, cricoid defects, and stomal anterior wall loss frequently exceed the possibilities of conventional resection and reconstruction. To outline the current role of microvascular reconstruction at the LTJ, with a focus on indications, techniques, and limitations from the perspective of otolaryngology and thoracic surgery. Narrative literature review of clinically established flap reconstruction techniques at the LTJ, including recent case series and key publications. For short, non-pretreated defects, cricotracheal resection and segmental tracheal resection with end-to-end anastomosis remain the standard of care. Microvascular reconstructions are mainly used for long, circumferential LTJ defects, extensive cricoid loss, previously irradiated or multiply operated regions, and complex treatment interventions. The radial forearm free flap is currently the best-established option for long tracheal and laryngotracheal defects and can be combined with cartilage reinforcement or a mucosal lining. Osseous flaps such as the medial femoral condyle flap and the thoracodorsal artery scapular tip flap allow larynx-preserving reconstruction, with restoration of a stable ring or posterior framework in selected cases. Prefabricated constructs, ALT-based flaps, jejunal grafts, and pedicled flaps play an adjunctive role in borderline and salvage situations. Microvascular reconstruction extends the therapeutic spectrum for LTJ surgery beyond conventional resection techniques and can provide a functional airway in highly complex situations and with acceptable morbidity. Given the limited evidence base from case series, interdisciplinary planning and centralisation of these procedures in experienced centres are essential.

Medial Tibial Plateau depth is a key morphological determinant of cartilage lesion severity in anteromedial knee osteoarthritis.

Femoral Condylar Consumption Index (FCCI): A geometric MRI predictor of lateral meniscal lesion and re-tear.

The characteristics of patients that promote progressive cartilage degradation following patellar dislocations are not well understood. The study hypothesis is that associations relating cartilage degradation to low BMI, high activity and youth in the early months following patellar dislocation are not exhibited for contralateral knees or a longer time from injury. Quantitative MRI-based evaluation of injured and contralateral knees occurred within 5 months of a unilateral patellar dislocation (baseline evaluation, 36 subjects) and beyond 5 months (follow-up evaluation, 20 subjects). Linear regressions correlated T1ρ relaxation times for regions of patellofemoral and tibiofemoral cartilage against body mass index, age, and activity level. Long relaxation times indicate cartilage degradation. Baseline T1ρ relaxation times were significantly inversely correlated with body mass index throughout patellofemoral cartilage for injured knees (p < 0.001 to 0.03). Similar relationships were identified for all regions of patellar cartilage for contralateral knees (p = 0.011 to 0.015). Injured and contralateral T1ρ relaxation times were also correlated with activity level (positive correlation) and age (inverse correlation) for various regions of cartilage (p < 0.001 to 0.047). The only significant correlations for the follow-up groups related increasing body mass index to long cartilage T1ρ relaxation times for the contralateral medial trochlear groove, femoral condyles, and lateral tibial plateau (p = 0.008 to 0.026). The attributes of a dislocation that determine characteristics influencing cartilage are common to both knees but dissipate over time. A systemic, transient inflammatory response to injury could explain the short-term similarities between injured and contralateral knees following dislocation.

Background:Trochlear dysplasia (TD) is considered by many to be an important risk factor for patellar dislocation (PD), and its accurate assessment is critical. Several methods to quantify TD exist, but none stand alone as the ideal measurement.Hypothesis:The authors hypothesized that a novel TD measurement, the lateral trochlear anterior condyles (LTAC) angle, is a simple yet comprehensive and reproducible technique for describing TD. Patients with PD will have lower LTAC angles (flatter trochlear groove [TG]) than controls; patients with recurrent PDs (RPDs) will have lower LTAC angles (flatter TG) than those with onetime PDs (OPDs).Study Design:Cross-sectional study; Level of evidence, 3.Methods:A retrospective case-control study was conducted of pediatric and adolescent patients with a history of PD versus a control group of age- and sex-matched patients (individuals with anterior cruciate ligament injuries but no history of PD). A subgroup analysis compared those with OPD versus RPDs. The LTAC angle was defined as the angle formed between (1) the lateral trochlear facet and (2) a line drawn connecting the most anterior portion of the medial and lateral femoral condyles. The LTAC angle was measured at 4 axial magnetic resonance imaging levels within the TG, assessing cartilaginous and osseous surfaces. LTAC mean differences were analyzed (all PDs vs controls; RPDs vs OPDs), and cutoffs for distinguishing all PDs from controls were based on the Youden index.Results:There were 170 patients (mean ± SD age, 15.29 ± 2.45 years; 58% female) with a history of PD (106 RPDs and 67 OPDs) and 98 controls (mean age, 15.56 ± 1.40 years; 47% female). Significant differences in mean LTAC values were observed between PD cases and controls at all levels of the TG on cartilaginous and osseous surfaces (P < .001). Patients with RPDs demonstrated significantly lower cartilaginous LTAC values than those with OPDs across all TG levels (P < .05), while osseous LTAC values showed no statistically significant differences at the proximal 3 axial levels (P > .05).Conclusion:The LTAC angle, a novel TD measurement, consistently shows lower values in PD cases as compared with controls throughout the TG. The LTAC angle combines the advantages of the lateral trochlear inclination angle and the sulcus angle (TG congruency) and assesses TD using a 1-image technique. The LTAC angle is a simple yet comprehensive measurement technique for TD that is able to stratify patients based on a history of PD events.

Background: Pediatric mandibular reconstruction requires restoration of mandibular continuity while accounting for craniofacial growth, dental development, and long-term functional outcomes. Although vascularized osseous free flaps are widely used, the influence of defect characteristics and patient age on donor-site selection remains unclear. This study evaluated patterns of flap selection in relation to mandibular defect classification and patient age. Methods: This retrospective single-center cohort study included 75 patients aged 1–18 years who underwent microvascular mandibular reconstruction between 2011 and 2025. Donor sites included the fibula, iliac crest, and medial femoral condyle. Mandibular defects were classified according to the Brown classification. Associations between defect class, age, donor-site selection, and flap loss were analyzed. Results: The fibula flap was used most frequently (52.0%), followed by the iliac crest (44.0%) and medial femoral condyle (4.0%). Donor-site selection was significantly associated with Brown defect classification (p < 0.001). Age differed across donor-site groups, with fibula flaps used more often in younger patients and iliac crest flaps in older patients. However, after stratification by defect class, age-related differences were not statistically significant. Overall flap survival was 93.3%, and age was not associated with total flap loss. Conclusions: Donor-site selection showed a stronger association with defect characteristics than with patient age. Observed age-related patterns likely reflect differences in defect morphology. These findings support the clinical relevance of a defect-oriented framework for pediatric mandibular reconstruction; however, flap selection remains individualized and influenced by multiple patient- and surgeon-related factors.

Background:Focal chondral and osteochondral defects in the knee are often difficult to treat. One solution is the use of osteochondral allograft (OCA) transplantation. The literature deliberates lesions located in the medial femoral condyle (MFC), but little is discussed regarding the lateral femoral condyle (LFC).Purpose:To compare graft survivorship and patient-reported outcomes (PROs) among patients who underwent OCA transplantation of the LFC to the MFC.Study Design:Cohort study; Level of evidence, 3.Methods:A total of 319 patients who underwent primary OCA transplantation of the LFC (n = 111) and MFC (n = 208) were identified. Reoperations were recorded, and OCA failure was defined as allograft removal. PROs included the Knee injury and Osteoarthritis Outcomes Score (KOOS), the International Knee Documentation Committee (IKDC) score, the modified Merle d’Aubigné-Postel score, and satisfaction.Results:Patients with MFC grafts were older than those with LFC grafts (33 and 26 years, respectively; P < .001) and had a slightly higher body mass index (25.6 and 24.4 kg/m2, respectively; P = .039). Diagnosis, sex, and allograft size did not differ between groups. Reoperations occurred in 27.9% of MFC grafts and 26.1% of LFC grafts (P = .737). OCA failure occurred in 12% of MFC grafts and 9% of LFC grafts (P = .413). The 10-year survivorship was 88% for MFC grafts and 92.9% for LFC grafts (P = .543). Among in situ allografts, the mean follow-up duration was 9.4 years for MFC grafts and 8.6 years for LFC grafts (P = .313). At the latest follow-up, the IKDC pain subscale and total scores were similar, but function subscale scores differed significantly between LFC (6.8 ± 2.4) and MFC (7.5 ± 2.1) patients (P = .019). KOOS and Merle d’Aubigné-Postel scores were similar between patients with MFC and LFC grafts. Patients with MFC grafts reported higher satisfaction than those with LFC grafts (93.7% vs 86.3%, respectively; P = .041).Conclusion:OCA transplantation of the LFC demonstrates high graft survivorship and significant improvement in PROs at mid-term follow-up. Clinical outcomes, reoperation rates, and survivorship were comparable to OCA transplantation of the MFC. These findings suggest that OCA transplantation of the LFC represents a reliable treatment option in appropriately selected patients.

Persistent, static anterior tibial translation (sATT) alterations following anterior cruciate ligament reconstruction (ACLR) may influence cartilage health. T2 relaxation times and serum biomarkers of cartilage degradation/bone resorption provide insight into osteoarthritis development. The relationship between sATT and these markers is unknown. We aimed to determine if changes in sATT are associated with early signs of osteoarthritis development, preoperatively and 6 months post-ACLR. We conducted a secondary analysis of a prospective cohort study (Level 2) of 29 participants with ACL injury (N = 29) through 6 months post-ACLR. Magnetic resonance imaging (MRI) was used to measure sATT in the medial and lateral tibiofemoral compartments and quantitative MRI was used to assess cartilage T2 relaxation times within 1 month of ACL injury (pre-ACLR) and 6 months post-ACLR. Serum biomarkers associated with cartilage and bone breakdown, including cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-3 (MMP-3) and N-terminal telopeptide (NTX), were analyzed at pre-ACLR and 6 months. Pearson's correlations were used to determine associations between sATT with T2 relaxation time and serum biomarkers. sATT persisted in both medial and lateral compartments after ACLR and was significantly greater at 6 months on the injured knee compared to the uninjured knee (average difference of 1.6 ± -2.1 mm [p < 0.001] and 1.5 ± 2.8 mm [p = 0.007] in the medial and lateral compartments, respectively). Greater interlimb difference in sATT at 6 months correlated with increased (worse) T2 relaxation times in the anterior lateral (r = 0.386, p = 0.038) and medial (r = 0.426, p = 0.021) femoral condyles. No significant associations were found between sATT and T2 relaxation times in other cartilage regions or with serum biomarker levels (p > 0.05). sATT persisted after ACLR and greater persistence of sATT was linked to elevated T2 relaxation times in the anterior femoral condyles. These findings may provide further insight into a mechanism of cartilage deterioration after ACLR. Level II.

Variability in knee pivoting behavior and condylar translation: Insights from a dynamic CT study.

Medial meniscus posterior root tears (MMPRTs) have been associated with rapidly progressive cartilage degeneration when left untreated in adults. However, their clinical presentation, tear morphology, and associated cartilage pathology remain poorly characterized in pediatric and adolescent patients. To identify risk factors for medial tibiofemoral compartment cartilage injury in pediatric and adolescent patients undergoing MMPRT repair, and secondarily to characterize MMPRT morphologies and skeletal maturity-associated injury patterns. Case series; Level of evidence, 4. Patients <19 years of age who underwent a transosseous MMPRT repair between 2015 and 2025 across 5 institutions were included. Operative records were reviewed to classify MMPRT morphology using the LaPrade classification and to document concomitant ligamentous procedures. The presence, location, and severity of arthroscopically identified medial tibiofemoral compartment cartilage injuries involving the medial femoral condyle (MFC) and/or medial tibial plateau were graded using the International Cartilage Regeneration & Joint Preservation Society (ICRS) classification. Patients with and without medial compartment cartilage injury were compared, and multivariable logistic regression was used to identify risk factors associated with its presence at the time of surgery. A total of 75 patients underwent a transosseous MMPRT repair (mean age, 15.2 ± 2.3 years), and 40% were skeletally immature. The most common MMPRT morphology was a type 5 root avulsion (55%), followed by a type 2 complete radial root tear (36%). Skeletally immature patients more frequently sustained isolated MMPRTs (60% vs 11%; P < .001), whereas skeletally mature adolescents more commonly had ligament-associated MMPRTs (89% vs 40%; P < .001). Overall, medial compartment cartilage injury was arthroscopically identified in 34 patients (45%) at the time of surgery. Most cartilage injuries involved the MFC (82%) and were classified as ICRS grade 1 (15%) or grade 2 (62%), while 24% were high-grade (ICRS grade 3 or 4). Multivariable logistic regression demonstrated that age (OR per year, 1.33; 95% CI, 1.02-1.73; P = .03) and delayed surgery (≥90 days after injury) (OR, 4.96; 95% CI, 1.6-15; P = .005) were significantly associated with medial compartment cartilage injury. The association between delayed surgery and medial compartment cartilage injury remained consistent in a sensitivity analysis incorporating concomitant ligament injury. Concomitant medial compartment cartilage injury was arthroscopically identified in 45% of pediatric and adolescent patients undergoing MMPRT repair. While most of these cartilage injuries involved the MFC and were classified as ICRS grade 2, nearly one-quarter were high-grade lesions (ICRS grade 3 or 4). Increasing age and delayed surgery (≥90 days after injury) were significantly associated with medial compartment cartilage injury. Overall, these findings underscore the potential importance of timely recognition and surgical treatment of MMPRTs in young patients.

Background:Medial patellofemoral ligament reconstruction (MPFLR) is a common surgical procedure for the treatment of recurrent patellar instability. Techniques vary by graft type, fixation method, number of graft limbs, graft placement, and tensioning. Hamstring tendons are most commonly used, but autograft causes donor-site morbidity, while allograft increases cost and requires availability. Recent anatomic studies have described a medial patellofemoral complex (MPFC) with a broad attachment to both the superomedial patella and the distal medial quadriceps tendon, suggesting the need to restore a broad footprint across both sites.Indications:MPFLR may be performed in isolation or in combination with bony procedures that address structural malalignment. Recent evidence suggests a role for isolated MPFLR regardless of coronal alignment and patellar height, in the absence of severe dysplasia or jumping J sign. We present a modification of the MPFLR technique described by Fink et al, utilizing quadriceps tendon autograft to restore a broad footprint of the MPFC.Technique Description:A 6 to 7 mm–diameter partial-thickness strip of tendon is harvested from the medial quadriceps tendon, leaving a thin cuff of tendon intact medially for side-to-side repair. The graft is left intact at the patellar insertion and redirected 90°, beneath the intact medial tendon insertion. The graft base is attached to exposed bone on the medial aspect of the superomedial corner of the patella using an all-suture anchor. The free end is passed between layers 2 and 3 and fixed within a socket at the Schottle point on the medial femoral condyle using a resorbable interference screw.Results:The described technique utilizes the quadriceps tendon autograft for MPFLR. The graft is easily obtained through a slight proximal extension of the incision required for patellar graft fixation. Harvest is reliable and reproducible, with extremely low donor site morbidity.Discussion/Conclusion:Maintenance of graft origin at the proximal patella with secondary fixation at the superomedial patella combines the traditional construct for MPFLR (bone fixation at superomedial patella) with that described by Tanaka as medial quadriceps tendon femoral ligament reconstruction (attachment at medial quadriceps tendon insertion). Thus, the technique described here restores a larger footprint of the entire MPFC, more closely approximating normal anatomy.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.

Intra-articular lesions of menisci and cartilage are common in anterior cruciate ligament reconstruction (ACLR) and may differ between primary and revision procedures. Clarifying their prevalence, morphology, and risk factors is important for prognosis and surgical planning. To perform a systematic review and meta-analysis comparing the prevalence and risk factors for intra-articular injuries in primary versus revision ACLR. Systematic review and meta-analysis; Level of evidence, 4. Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the PubMed, MEDLINE, and Embase databases were searched, supplemented by citation review and author contact. Comparative studies reporting intraoperative meniscal and/or chondral findings in both primary and revision ACLRs were included. Pooled odds ratios with 95% confidence intervals were calculated using random- or fixed-effects models. Nineteen studies consisting of 37,423 ACLRs were included. Revision ACLR was associated with higher odds of meniscal injury (OR, 1.64; 95% CI, 1.12-2.41). Meniscal treatment did not differ significantly between groups. Chondral lesions were >3-fold more prevalent in revisions (OR, 3.53; 95% CI, 2.71-4.60), especially at the trochlea (OR, 3.21; 95% CI, 2.59-3.97; I2 = 33%), medial tibial plateau (OR, 3.12; 95% CI, 2.61-3.73; I2 = 0%), and medial femoral condyle (OR, 2.99; 95% CI, 2.30-3.89; I2 = 61%). High-grade lesions (Outerbridge/International Cartilage Regeneration & Joint Preservation Society grades 3 and 4) were consistently more common in revisions, with progression observed in up to 26% of intrapatient comparisons. Risk factors reported for intra-articular injuries on revision ACLR included older age, male sex, tunnel malposition, malalignment, increased tibial slope, longer time to revision, and prior meniscectomy. In this review of >37,000 ACLRs, revision status was associated with 1.6-fold higher odds of meniscal tears and 3.5-fold higher odds of chondral lesions compared with primary reconstruction. Chondral injury at revision was more prevalent across all compartments and consistently more severe, with the greatest risk observed in the trochlea and medial compartment. These findings demonstrate a substantially greater intra-articular disease burden at the time of revision surgery.

Lower-extremity coronal alignment influences joint loading, gait mechanics, and the progression of osteoarthritis, yet the relative contributions of hip and knee anatomy remain incompletely defined. Valgus lower extremity alignment has traditionally been attributed to lateral femoral condyle hypoplasia, but the major contributor to valgus alignment and that femoral version and tibial bowing are more strongly associated with valgus deformity. We performed a retrospective review of 122 consecutive primary total knee arthroplasties (57 valgus, 65 varus) with preoperative long-leg radiographs and hip-to-ankle computed tomography. Hip-knee-ankle angle, tibial shaft angulation, femoral version, and medial and lateral femoral condyle heights were independently measured by three blinded observers. Multivariate analyses of covariance were used to determine differences between groups for femoral version and bowing angle with age and sex as covariates; all other continuous variables were compared with two-tailed t-tests, and categorical variables with Chi-square analyses (α = 0.05). Valgus alignment demonstrated significantly lower femoral anteversion than varus alignment (5.5 [95% confidence interval (CI) 3.1 to 7.9] versus 10.3 [95% CI 8.0 to 12.5], P = 0.005) and a markedly higher prevalence of femoral retroversion (30 versus 3%, P < 0.001). Medial tibial bowing greater than 3° occurred in 50.9% of valgus knees compared with 3% of varus knees (P < 0.001). Unexpectedly, lateral femoral condyle height was slightly greater in the valgus group compared with the varus group (62.8 versus 60.9 mm, P = 0.025). Valgus lower extremity alignment is strongly associated with femoral retroversion and medial tibial bowing, but not lateral femoral condyle hypoplasia. These findings challenge long-standing assumptions about the pathogenesis of valgus deformity and underscore the importance of assessing femoral version and tibial morphology when planning total knee or hip arthroplasty.

To evaluate the predictive value of magnetic resonance imaging (MRI)-derived cross-sectional area (CSA) measurements of hamstring and peroneus longus tendons in estimating intraoperative autograft diameter during anterior cruciate ligament (ACL) reconstruction, and to identify clinically useful CSA cut-offs for achieving graft diameters ≥ 8mm. Fifty-two patients undergoing primary ACL reconstruction were included in this prospective observational study, with 26 each in the hamstring tendon (HT) and peroneus longus tendon (PLT) autograft groups. Preoperative CSA was measured on axial MRI at specific anatomical levels. Intraoperative graft diameters were recorded post- harvest. Correlation analysis and receiver operating characteristic curves were used to assess predictive value and determine CSA thresholds for adequate graft size. For the HT group, CSA measured at the medial femoral condyle showed the strongest correlation with intraoperative diameter (r = 0.782; p < 0.001), with an optimal CSA cut-off of ≥ 19.15mm² (AUC 0.917, sensitivity: 85%, specificity: 100%). For the PLT group, ankle-level CSA best predicted graft diameter (cut-off: ≥12.84mm², AUC 0.958, sensitivity: 95.8%, specificity: 100%). MRI-based CSA measurement provides a reliable, non-invasive method for predicting autograft adequacy. This study establishes clinically relevant CSA thresholds for HT and PLT tendons and is the first to report such values for PLT, aiding preoperative graft selection in ACL reconstruction.