Evaluation of the consistency of the MRI- based AI segmentation cartilage model using the natural tibial plateau cartilage.

OBJECTIVE: The study aims to evaluate the accuracy of an MRI-based artificial intelligence (AI) segmentation cartilage model by comparing it to the natural tibial plateau cartilage. METHODS: This study included 33 patients (41 knees) with severe knee osteoarthritis scheduled to undergo total knee arthroplasty (TKA). All patients had a thin-section MRI before TKA. Our study is mainly divided into two parts: (i) In order to evaluate the MRI-based AI segmentation cartilage model's 2D accuracy, the natural tibial plateau was used as gold standard. The MRI-based AI segmentation cartilage model and the natural tibial plateau were represented in binary visualization (black and white) simulated photographed images by the application of Simulation Photography Technology. Both simulated photographed images were compared to evaluate the 2D Dice similarity coefficients (DSC). (ii) In order to evaluate the MRI-based AI segmentation cartilage model's 3D accuracy. Hand-crafted cartilage model based on knee CT was established. We used these hand-crafted CT-based knee cartilage model as gold standard to evaluate 2D and 3D consistency of between the MRI-based AI segmentation cartilage model and hand-crafted CT-based cartilage model. 3D registration technology was used for both models. Correlations between the MRI-based AI knee cartilage model and CT-based knee cartilage model were also assessed with the Pearson correlation coefficient. RESULTS: The AI segmentation cartilage model produced reasonably high two-dimensional DSC. The average 2D DSC between MRI-based AI cartilage model and the tibial plateau cartilage is 0.83. The average 2D DSC between the AI segmentation cartilage model and the CT-based cartilage model is 0.82. As for 3D consistency, the average 3D DSC between MRI-based AI cartilage model and CT-based cartilage model is 0.52. However, the quantification of cartilage segmentation with the AI and CT-based models showed excellent correlation (r = 0.725; P values < 0.05). CONCLUSION: Our study demonstrated that our MRI-based AI cartilage model can reliably extract morphologic features such as cartilage shape and defect location of the tibial plateau cartilage. This approach could potentially benefit clinical practices such as diagnosing osteoarthritis. However, in terms of cartilage thickness and three-dimensional accuracy, MRI-based AI cartilage model underestimate the actual cartilage volume. The previous AI verification methods may not be completely accurate and should be verified with natural cartilage images. Combining multiple verification methods will improve the accuracy of the AI model.

Morphological and morphometric analysis of oblique popliteal ligament in North Indian population: a cadaveric study.

PURPOSE: To study the morphology and the morphometry of the oblique popliteal ligament (OPL). METHODS: Thirty cadaver knees were dissected to study the morphology and morphometry of the OPL. For the measurement of the morphology of the OPL a standard tape and the vernier callipers were used. RESULT: Out of 30 specimens 14 were Y shaped, 10 were band shaped, and 6 were Z shaped observed. Total length was measured on both the limbs, on the right side it was 4.5 ± 0.4 cm and on the left side 4.5 ± 0.5 cm was recorded. Width at the medial attachment was also measured on both the limbs, on the right side it was 4.6 ± 0.5 cm and on the left side 4.7 ± 0.5 cm was recorded. And width at the lateral attachment was recorded too, on the right side it was 4 ± 0.3 cm and on the left side it was 4 ± 0.3 cm. Width at the midpoint was recorded as on the right side 3.5 ± 0.2 cm and on the left side 3.5 ± 0.2 cm. CONCLUSION: The OPL is a thick ligament that arises as an extension of the semimembranosus, and it exists in various morphology which includes band, Y, Z, complex shapes.

Femoral anterior condyle height decreases as the distal anteroposterior size increases in total knee arthroplasty: A comparative study.

PURPOSE: The anterior flange height of the current femoral component increases with an increasing distal femoral anteroposterior dimension. During total knee arthroplasty (TKA), we have observed that a large femur may have a thinner anterior condyle, whereas a small femur may have a thicker anterior condyle. The first purpose of this study was to examine whether the femoral anterior condyle height decreases as the distal femoral anteroposterior size increases and whether gender differences exist in anterior condyle height. METHODS: A total of 1218 knees undergoing TKA intraoperative and computed tomography scans from 303 healthy knees were used to measure the anterior lateral condylar height (ALCH), anterior medial condylar height (AMCH), and the lateral anteroposterior (LAP) and medial anteroposterior (MAP) dimensions of distal femurs. The LAP and MAP measurements were used for adjustments to determine whether gender differences exist in anterior condyle heights. Linear regression analysis was performed to determine correlations between ALCH and LAP or between AMCH and MAP. RESULTS: There were significant differences between males and females in ALCH in both the CT and TKA groups and AMCH in the CT group (all P<0.01). After adjusting for LAP and MAP, there were significant gender differences in the lateral and medial condylar heights in both groups (P<0.01). There were significant negative correlations between ALCH and LAP values and between AMCH and MAP values in both CT and TKA measurements, with the LAP and MAP values increasing as ALCH and AMCH decreased. CONCLUSIONS: The results demonstrate that femoral anterior condylar height decreased with increasing anteroposterior dimension in both the medial and lateral condyle. In addition, this study also showed that anterior condylar heights are highly variable, with gender differences. The data may provide an important reference for designing femoral anterior flange thickness to precisely match the natural anterior condylar anatomy.

Tibia-first, gap-balanced patient-specific alignment technique achieves well-balanced gaps in 90% of cases by rebuilding bony anatomy within boundaries.

PURPOSE: Patient-specific alignment (PSA) technique tries to achieve balanced gaps and simultaneously rebuild the individual bony phenotype. The hypothesis was: PSA technique achieves balanced knees in a high percentage with more anatomical resections than adjusted mechanical alignment (AMA). METHODS: Three hundred sixty-seven patients underwent navigated total knee arthroplasty (TKA) with a tibia-first gap-balanced PSA technique. Resection boundaries for medial proximal tibia angle (MPTA) of 86-92°, mechanical lateral distal femoral angle (mLDFA) of 86-92°, and hip-knee-ankle angle (HKA) of 175-185° were defined. Preoperative and intraoperative parameters of HKA, MPTA, mLDFA, and gap widths were recorded. Depending on the coronal deformity, the patients were divided into three groups: varus HKA < 178°; straight 178-182° and valgus HKA > 182°. The stability was analysed by assessing the difference between medial and lateral extension and flexion gaps as well as between flexion and extension gaps. All PSA measurements were compared with data from a previously published AMA series. RESULTS: PSA achieved balanced gaps in extension, flexion and between flexion/extension in over 90% of cases, being similar to AMA. In PSA, MPTA and mLDFA were restored within 1°, except in extreme varus (MPTA difference 2°) and valgus knees (mLDFA difference 3°). This was caused by the defined boundaries of the alignment technique. This individualised reconstruction led to significantly more anatomical resections of all tibia and femur resections. CONCLUSION: A tibia-first, gap-balanced PSA technique achieves balanced joints in more than 90% of cases. By maintaining preoperative MPTA and mLDFA to a high extent, far more anatomical resections, compared to AMA were performed. Future studies need to be conducted to investigate whether those promising intraoperative results correlate with postoperative patient outcomes and whether patients outside the 5° corridor have higher failure rates. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Ten Flaws of Systematic Mechanical Alignment Total Knee Arthroplasty.

Mechanical alignment (MA) and its tenets have been considered essential for total knee arthroplasty (TKA) success since they were introduced in 1973. However, over time, there have been colossal advances in our knowledge and understanding of the anatomy and kinematics of the knee, as well as in surgical precision and implants. However, the MA systematic principles of prosthetic arthroplasty and implant position related to the lower-extremity mechanical axis, have only recently been called into question. The high rates of dissatisfaction and residual pain reported after MA TKA prompted this questioning, and that leaves plenty of room for improvement. Despite the general consensus that there is great variability between patients' anatomy, it is still the norm to carry out a systematic operation that does not consider individual variations. Evolving to a more personalized arthroplasty surgery was proposed as a rational and reasonable option to improve patient outcomes. Transitioning to a personalized TKA approach requires questioning and even disregarding certain MA TKA principles. Based on current knowledge, we can state that certain principles are erroneous or unfounded. The aim of this narrative review was to discuss and challenge 10 previously accepted, yet we believe, flawed, principles of MA, and to present an alternative concept, which is rooted in personalized TKA techniques.

Predicting postoperative coronal alignment after fixed-bearing unicompartmental knee arthroplasty using a new morphological assessment method: the arithmetic hip-knee-ankle angle.

PURPOSE: Only a few reports have been published so far on factors that predict postoperative coronal alignment after unicompartmental knee arthroplasty (UKA). The purpose of this study is to clarify the relationship between the arithmetic hip-knee-ankle angle (aHKA) and postoperative coronal alignment after medial fixed-bearing UKA. METHODS: One hundred and one consecutive patients (125 knees) who underwent medial fixed-bearing UKA were assessed. Pre- and postoperative coronal HKA angles, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and the thickness of the tibial and femoral bone cut were measured. aHKA was calculated as 180° - LDFA + MPTA. Correlations between postoperative HKA angle and aHKA, LDFA, and MPTA were investigated by single regression analysis. After the patients were divided into three groups according to the postoperative HKA angle, i.e., HKA angle > 180°, 175° < HKA angle ≤ 180°, and HKA angle ≤ 175°, aHKA, LDFA, MPTA, preoperative HKA angle, and the thickness of the distal femoral as well as tibial bone cut were compared among the three groups. RESULTS: aHKA and MPTA were positively correlated with postoperative HKA angle, while no correlation was found between postoperative HKA angle and LDFA. Among the three groups classified by postoperative HKA angle, significant differences were found in aHKA, MPTA, and preoperative HKA angle, while no significant difference was found in LDFA and the amount of distal femoral and tibial osteotomies. CONCLUSIONS: aHKA was correlated with postoperative HKA angle after medial fixed-bearing UKA, which was probably due to the influence of MPTA.

Saucerization of complete discoid lateral meniscus is associated with change of morphology of the lateral femoral condyle and tibial plateau.

PURPOSE: To determine the effect of saucerization surgery on knee joint morphology associated with a complete discoid lateral meniscus (DLM) using magnetic resonance (MR) imaging. METHODS: This retrospective study included cases had undergone saucerization surgery for symptomatic DLM between 2007 and 2022. All cases were divided into two by age group: < 12 (U13) and > 13 (O13). The cases in the match group were randomly selected from preoperative cases in the O13 group matched with the age at the final follow-up (F/U) of cases in the U13 group. The following morphological parameters were evaluated using MR images preoperatively and at the final postoperative F/U in each group: anterior obliquity of the lateral tibial plateau (AOLTP), posterior obliquity of the lateral tibial plateau (POLTP), and the lowest point of the lateral femoral condyle (LPLFC). Each parameter was compared between the U13 preoperative (pre-OP) group and the O13 pre-OP group, the preoperative and final follow-up in the U13, and the U13 group at the final F/U and the match group preoperatively. RESULTS: A total of 77 cases were evaluated. 31 cases were in the U13 pre-OP group and 46 were in the O13 pre-OP group. With a minimal F/U of 2 years, 27 cases in the U13 group and 36 in the O13 group were included. The mean F/U period was 4.6 years in the U13 group and 3.2 years in the O13 group. 32 cases were included in the match group. In the match group, the inclination of the POLTP was significantly larger (P = 0.042) and the LPLFC was more lateral (P = 0.0034) than at the final F/U in the U13 group. CONCLUSIONS: Saucerization surgery for DLM in juvenile patients can prevent progression to the characteristic bone morphology DLM. These results could help the surgeon making the decision when the surgery would be performed for symptomatic DLM patients. LEVEL OF EVIDENCE: Retrospective comparative study; level of evidence, 3.

Posteromedial capsular anatomy of the tibia for consideration of the medial meniscal support structure using a multidimensional analysis.

Medial meniscal extrusion (MME) is a structural abnormality that leads to early knee osteoarthritis; however, its formation remains debated. For anatomical consideration of the mechanism underlying MME formation, we examined the capsular attachment on the posteromedial tibia and its layered association with the semimembranosus. Fourteen knees of eight body donors were analyzed in this study; six knees were grouped for macroscopic analysis, whereas four knees each were grouped for histological and phosphotungstic acid-enhanced micro-computed tomography analyses. The capsular attachment varied in width according to location and was not distant from the articular cartilage and posterior root. A portion of the posteromedial joint capsule formed the semimembranosus tendinous sheath. The dense fibrous membrane superficial to the semimembranosus, which was continuous from its tendinous sheath, existed as one of the layers of the joint capsule. The aforementioned findings were confirmed in all specimens. Based on the capsular attachment and its layered association with the semimembranosus, the conventional posteromedial knee ligaments may be only a part of the joint capsule divided into two layers by the semimembranosus. If the coordinated action of the joint capsule and semimembranosus partially contributes to the medial meniscus stability, such a structural problem may affect MME formation.

The continuous structure of the joint capsule and meniscus in the pig knee.

The knee joint capsules composed of a fibrous layer and a synovial layer. The knee meniscus consists of the superficial network, lamellar layer, tie fibre and circumferential bundles. However, the continuous structure of the knee joint capsule and meniscus has not been reported. Fetal and adult pigs were used to investigate the structural relationship between the stifle joint capsule and meniscus based on the gross anatomy and histological findings. In the gross anatomical examination, the joint capsule appeared to have separated attachments to the meniscus, except for the lower aspect of the popliteal hiatus. Histologically, the lower half of the popliteal hiatus was found to have separated attachments, with vessels running between the attachments of the joint capsules. The synovial layer of the joint capsule continued to the superficial network, and the fibrous layer of the joint capsule continued to the lamellar layer and tie fibres. There were two routes of arterial entry into the meniscus: intracapsular and intercapsular. It appeared that the presence of separated attachments of the joint capsule was necessary to allow the intercapsular route. This study clarified for the first time the routes of feeding vessels entering the meniscus and proposed to call this entry point the meniscus hilum. We consider that this detailed anatomical information is important for understanding the continuation between the joint capsule and the meniscus.

Internal Structural Connections in the Popliteus Tendon Complex with Posterior Cruciate Ligament and Clinical Implications / Conexiones Estructurales Internas en el Complejo Tendón Poplíteo con Ligamento Cruzado Posterior e Implicaciones Clínicas

SUMMARY: At present, the anatomical relationship the mid-portion of popliteus tendon complex (PTC) and the surrounding tissues is still unclear, especially its relationship to the posterior cruciate ligament (PCL). It affected the anatomical reconstruction of the posterolateral complex (PLC) injury. A total of 30 cases of the adult human knee joint fixed with formalin were used. Sagittal sections were made in 14 knee joints by the P45 plastination technique and dissection of 16 cases of knee joints. The P45 section revealed that the popliteus muscle fascia ran superiorly over the posterior edge of the tibial intercondylar eminence, and turned forward to be integrated into the PCL. Laterally, near the posterior edge of the lateral tibial plateau, the popliteus tendon penetrates through the articular capsule (AC), where two dense fibrous bundles were given off upwards by the popliteus tendon: one was the ventral fiber bundle, which ran superiorly over the posterior edge of the tibial plateau and then moved forwards to connect with the lateral meniscus; the dorsal fibers bundle ascended directly and participated in the AC. Meanwhile, the popliteus muscle dissection showed that at the posterior edge of the platform of the lateral condyle of the tibia, at the tendon-muscle transition, the PTC and AC were anchored to PCL.

En la actualidad, la relación anatómica entre la porción media del complejo tendinoso poplíteo (CTP) y los tejidos circundantes aún no está clara, especialmente su relación con el ligamento cruzado posterior (LCP). Esto afecta la reconstrucción anatómica de la lesión del complejo posterolateral (LCP). Se utilizaron un total de 30 casos de articulaciones de rodillas humanas de individuos adultos fijadas con formalina. Se realizaron cortes sagitales en 14 articulaciones de rodilla mediante la técnica de plastinación P45 y disección de 16 casos de articulaciones de rodilla. La sección P45 reveló que la fascia del músculo poplíteo discurría superiormente sobre el margen posterior de la eminencia intercondílea tibial y giraba hacia delante para integrarse en el LCP. Lateralmente, cerca del margen posterior de la platillo tibial lateral, el tendón poplíteo penetra a través de la cápsula articular (CA), donde el tendón poplíteo desprendió hacia arriba dos haces fibrosos densos: uno era el haz de fibras ventral, que corría superiormente sobre el margen posterior de la meseta tibial y luego se movió hacia adelante para conectar con el menisco lateral; el haz de fibras dorsales ascendía directamente y participaba en la CA. Por su parte, la disección del músculo poplíteo mostró que en el margen posterior del platillo del cóndilo lateral de la tibia, en la transición tendón-músculo, el CTP y el AC estaban anclados al LCP.

Immunohistochemical analysis of the ligamentum mucosum is the key to understand its clinical usefulness.

Ligamentum Mucosum(LM) is a ligamentous structure within the synovial layer of the knee joint capsule. For a long time LM was perceived as the vestigial remnant from the embryological development of the knee. Being treated as an irrelevant structure LM was often the first victim of shaver during arthroscopy. However, last years have shown increased interest in this structure due to its potentially significant clinical role. Our aim was to classify LM based on its morphological characteristics and examine its microanatomy using immunohistochemical analysis to reveal the potential clinical value for surgeons. We have examined sixteen fresh frozen lower limbs, 6 females (mean age 83.1 ± 3.4 years) and 10 males (mean age 84.2 ± 6.8 years). Classical histological H+E stain was routinely conducted. Subsequently, CD31 antibody (DAKO, Monoclonal Mouse Anti-Human, Clone JC70A) was used to mark vascular epithelium. Monoclonal Mouse Anti-Human Neurofilament Protein (NFP) antibody (DAKO, Clone 2F11) was used to expose the nerves. Moreover, we have conducted arthroscopic visualizing and suturing LM to the torn ACL during routinely performed arthroscopic suturing of the ACL. The dissection process has revealed that LM was present only in 75% of cases. Histological examination confirmed the presence of longitudinal collagen fiber bundles in all samples. Tiny nerves were confirmed by NFP, along the subsynovial layer in all samples. CD-31 immunostain revealed the presence of many vascular vessels along the entire ligament, especially well developed at its distal end. Our study has revealed that LM contains rich vascular network. Thus, it may be a donor for the revascularization process after ACL tear or reconstruction which may improve the recovery. Another great advantage of the LM is the presence of nerves along the subsynovial layer, hopefully they may serve as the source of reinnervation and hence better clinical outcome. Based on our results we believe that seemingly irrelevant LM may be very useful during surgical procedures in the knee region. Suturing LM to the ACL may not only prevent the infrapatellar fat pad from subluxation but also improve the blood flow and reinnervation of the injured ACL. Until now there are only a few studies examining microanatomy of the LM. This basic knowledge may serve as the foundation for surgical procedures. Hopefully our findings may be useful for surgeons while planning surgical procedures or clinicians while diagnosing patients who suffer anterior knee pain.

[Progress of injection sites of local infiltration analgesia in total knee arthroplasty].

Objective: To review the research progress of injection sites of local infiltration analgesia (LIA) in total knee arthroplasty (TKA). Methods: The relevant domestic and foreign literature in recent years was extensively reviewed. The neuroanatomy of the knee, and the research progress of the selection and the difference of effectiveness between different injection sites of LIA in clinical studies were summarized. Results: Large concentrations of nociceptors are present throughout the various tissues of the knee joint. Patellar tendon, subpatellar fat pad, lateral collateral ligament insertions, iliotibial band insertions, suprapatellar capsule, and posterior capsule were more sensitive to pain. Most current studies support injections into the lateral capsule, collateral ligament, retinaculum, quadriceps tendon, fat pad, and subcutaneous tissue. Whether to inject into the back of the knee and subperiosteum is controversial. Conclusion: The relative difference of knee tissue sensitivity to pain has guiding significance for the selection of LIA injection site after TKA. Although researchers have conducted clinical trials on injection site and technique of LIA in TKA, there are certain limitations. The optimal scheme has not been determined yet, and further studies are needed.

Effect of demographic features on morphometric variables of the knee joint: Sample of a 20 to 40-year-old Turkish population.

This study aimed to investigate the relationship between body mass index (BMI), age, and sex and morphological risk factors that may cause internal knee injuries. The magnetic resonance images of 728 participants who met the inclusion criteria and had a mean age of 34.4 ±â€…6.8 years were analyzed retrospectively. Demographic differences were analyzed by measuring 17 morphological parameters known to be associated with internal knee injuries. Men had a higher anterior cruciate ligament length (ACLL), anterior cruciate ligament width, (ACLW) lateral femoral condylar width (LFCW), medial femoral condylar width (MFCW), lateral femoral condylar depth (LFCD), distal femoral width (DFW), and intercondylar femoral width (IFW) than women (P < .05). By contrast, the medial meniscus bone angle (MMBA) was lower in men than in women (P < .05). Women aged 31 to 40 years had a lower Insall-Salvati index (ISI) and lateral tibial posterior slope (LTPS) than those aged 21 to 30 years (P < .05), whereas men aged 31 to 40 years had a lower ISI than those aged 21 to 30 years (P < .05). Women with BMI ≥ 30 had a higher LFCW and MFCW but a lower ISI than those with BMI < 30 (P < .05). Men with BMI ≥ 30 had a higher LFCW, MFCW, DFW, and MMBA than those with BMI < 30 (P < .05). The use of value ranges structured according to demographic characteristics, rather than a single value range for all patient groups, may contribute to the evaluation and treatment of the morphological features that are thought to be effective in the development of internal knee injuries. These values may also shed light on future radiological risk scoring systems and artificial intelligence applications in medicine.

Particularities on Anatomy and Normal Postsurgical Appearances of the Knee.

Detailed knowledge of anatomy helps to understand pathologic processes. This article focuses on the anatomy and functionality of the knee, with emphasis on recently studied concepts and anatomic features that have an association with the development of pathology. The most common anatomic variants posing a challenge for diagnosis and other common findings in asymptomatic patients are reviewed. Good understanding of the different surgical procedures helps in providing as much information as possible to guarantee a positive outcome, improving prognosis. We review what are the commonly expected postsurgical appearances and the most common postsurgical complications.

Reappraisal of the proximal tibia anatomy in Turkish population.

OBJECTIVE: Total knee arthroplasty has been popular in recent years. Morphometry of proximal tibia is important for surgeons to perform successful total knee arthroplasty. Aim of this study was to reappraise the proximal tibia morphometry. METHODS: In this study, 57 human dry tibia were evaluated. Anteroposterior and mediolateral dimensions of tibial condyles, maximum width of superior articular surface and length of tibia were measured. Furthermore, morphometric measurements of the intercondylar area and Gerdy's tubercle (infracondylar tibial tubercle) were done. All measurements were performed by two observers using a digital caliper. RESULTS: Mean anteroposterior and mediolateral dimensions of medial tibial condyle were found 39.76 and 23.27 mm, respectively. Mean anteroposterior and mediolateral dimensions of lateral tibial condyle were measured 34.72 and 21.83 mm, respectively. Mean anteroposterior dimension of intercondylar area was 41.62 mm. Shape of the Gerdy's tubercle was oval in 76.8%, irregular in 12.5%, and triangular in 10.7%. Texture of the tubercle was smooth in 85.7% and rough in 14.3%. Mean superoinferior and mediolateral dimensions of Gerdy's tubercle were 12.28 and 10.27 mm, respectively. Anteroposterior and mediolateral dimensions of tibial condyles were significantly higher (p < 0.05) for the medial condyle. Positive and statistically significant correlations were found between the tibial length and the other parameters (p < 0.05, r > 0.40). CONCLUSION: The morphometric data of tibial plateau are important for surgeons during total knee arthroplasty. The superoinferior and mediolateral dimensions of the Gerdy's tubercle, the distance between Gerdy's tubercle and tibial tuberosity, the distance between Gerdy's tubercle and lateral tibial plateau were measured for the first time in our study. The data obtained from this study can be used as a guideline in designing tibial component of the total knee prosthesis in Turkish population. In arthroplasty, patient-specific prosthetic implants may eradicate implant mismatch in the near future.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm.

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

The coronal alignment technique impacts deviation from native knee anatomy after total knee arthroplasty.

PURPOSE: The aim of this study was to analyze and quantify the changes in native coronal alignment of a population of TKA patients according to different alignment goals. METHODS: Five hundred and twenty TKAs were analyzed. The following angles were measured using an image-free navigation system prior to prosthetic implantation: medial femorotibial mechanical angle without stress and with maximum manual stress to reduce the deformity, medial distal femoral mechanical angle, medial proximal tibial mechanical angle. The native angles were derived from the osteoarthritic knee angles using a validated correction technique, and the overall, femoral and tibial coronal phenotypes were defined. Five different coronal alignment techniques were simulated: mechanical (MA), restricted mechanical (RMA), anatomical (AA), kinematic (KA) and restricted kinematic (RKA). The overall, femoral and tibial coronal phenotypes were compared before and after TKA. The primary endpoint was the binary criterion of whether or not TKA restored the natural overall phenotype. Secondary endpoints were the binary criteria of whether or not the natural femoral and tibial phenotypes were restored by TKA. The rates of restored and non restored phenotypes were compared with a Chi-square test at a 0.05 level of significance, with post hoc tests between all pairs of techniques at a 0.01 level of significance. RESULTS: The overall phenotype was restored significantly differently by the five alignment techniques: 15% for MA, 23% for RMA, 2% for AA, 100% for KA and 79% for RKA (p < 0.001). There was a significant difference between each of the technique pairs (p < 0.01 to p < 0.001), except for the mechanical alignment-restricted mechanical alignment pair. The femoral phenotype was restored significantly differently by the five alignment techniques: 37% for MA, 58% for RMA, 19% for AA, 100% for KA and 85% for RKA (p < 0.001). The tibial phenotype was restored significantly differently by the five alignment techniques: 36% for MA, 36% for RMA, 17% for AA, 100% for KA and 88% for RKA (p < 0.001). There was a significant difference between each pair of techniques for both femoral and tibial phenotypes (p < 0.01 to p < 0.001). CONCLUSION: Except for the kinematic alignment technique, the various alignment techniques induce significant changes in the pre-arthritic anatomy of the TKA patient. The surgeon must be aware of these modifications. The clinical relevance of this alteration still needs to be defined. LEVEL OF EVIDENCE: III.

Measurement of Medial Tibial Eminence Dimensions for the Clinical Evaluation of ACL-Injured Knees: A Comparison between CT and MRI.

Anterior cruciate ligament (ACL) injuries commonly lead to translational and rotational tibiofemoral instability. The morphology of the medial tibial eminence (MTE) has received increased attention regarding its role in tibiofemoral stability in ACL-injured knees. Therefore, quantification of MTE dimensions on clinical imaging may help clinicians predict knee stability after ACL injury. Although magnetic resonance imaging (MRI) is routinely obtained in patients with ACL injuries, whether the dimensions of the MTE can be accurate quantified on MRI is unknown. The purpose of this study was to assess the degree of correlation between measurements of MTE height and width on computed tomography (CT) versus MRI. An institutional picture archiving and communication system imaging database was used to identify patients aged between 15 and 60 years who received concurrent MRI and CT of the same knee within a 1-year interval. Knees with significant arthrosis, deformity, intraarticular fracture, or hardware-related artifact that obscured visualization of the MTE were excluded. Mean differences and interstudy agreement between CT and MRI MTE measurements were compared using concordance correlation coefficient (r c) and Bland-Altman analysis. A total of 41 knees in 38 patients (mean age, 37 years; 82% male) were analyzed. Interrater reliability for CT and MRI measurements was high (intraclass correlation coefficient = 0.740-0.954). On coronal CT and MRI, mean MTE height measurements were 10.4 ± 1.9 and 10.4 ± 1.8 mm, respectively; mean MTE width measurements were 14.6 ± 3.6 and 14.2 ± 3.0 mm, respectively. On sagittal CT and MRI, mean MTE height measurements were 11.6 ± 1.7 and 11.7 ± 1.7 mm, respectively; mean MTE width measurements were 36.5 ± 4.8 and 36.2 ± 5.0 mm, respectively. Good agreement was observed between CT and MRI measurements of MTE height and width on coronal and sagittal planes (r c = 0.947-0.969). Measurements of MTE height and width were similar on MRI relative to CT on both coronal and sagittal planes. MRI may be suitable for characterizing the dimensions of the MTE when clinically evaluating patients with ACL injuries, potentially allowing for individualized patient care.

Considerable inter-individual variability of tibial geometric ratios renders bone-implant mismatch unavoidable using off-the-shelf total knee arthroplasty: a systematic review and meta-analysis.

PURPOSE: The purpose of this systematic review and meta-analysis was to investigate the variability in tibial geometric ratios among knees of different sexes and races to determine whether commercially-available tibial baseplates accommodate the morphologic diversity. The hypothesis was that anthropometric studies report considerable variability of tibial geometric ratios among sexes and races. METHODS: This systematic review and meta-analysis was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) criteria. Two authors independently conducted an electronic search using MEDLINE® and Embase® on 28 January 2021 for clinical studies reporting on tibial geometric ratios. Tibial geometric ratios, as reported by the clinical studies, were represented by plotting their means and two standard deviations for comparison to two symmetric and two asymmetric commercially-available tibial baseplates. RESULTS: A total of 27 articles that reported on a combined total of 20,944 knees were eligible for data extraction. Variation in tibial aspect ratios was equal among sexes. The greatest variation in aspect ratio was observed among East Asians, followed by Caucasians, African-Americans, Indian and Middle Easterns. The variation in tibial asymmetry ratio was larger among men compared to women. The greatest variation in asymmetry ratio was observed among African-Americans, followed by Caucasians, East Asians, Indian and Middle Easterns. Bone-implant mismatch of > 3 mm overhang or > 4 mm under-coverage with four commercially-available tibial baseplates occurred in large proportions of knees due to variations in aspect ratio (in 17-100% of knees) and asymmetry ratio (in 7-100% of knees). CONCLUSION: Anthropometric studies reported considerable inter-individual variability of tibial geometric ratios, which exceeded effects of sexual dimorphism and racial diversity. Bone-implant mismatch may be unavoidable in a large proportion of knees, when considering that a surgeon generally only uses one or a few TKA brands. These findings support the drive towards patient-specific implants to potentially achieve accurate bone-implant fit by implant customisation. LEVEL OF EVIDENCE: IV.

Evaluation of the knee joint morphology associated with a complete discoid lateral meniscus, as a function of skeletal maturity, using magnetic resonance imaging.

INTRODUCTION: A discoid lateral meniscus (DLM) is associated with increased risk for meniscal tears and progression of knee joint osteoarthritis. Our aim was to differentiate knee joint morphology between patients with and without a DLM, as a function of skeletal maturity, using magnetic (MR) imaging. MATERIALS AND METHODS: This was a retrospective analysis of MR images of the knee for 110 patients, 6-49 years of age. Of these, 62 were in the open physis group (38 with a DLM) and 48 in the closed physis group (23 with a DLM). The following morphological parameters were measured: anterior obliquity of the lateral tibial plateau (AOLTP), posterior obliquity of the lateral tibial plateau (POLTP), the lowest point of the lateral femoral condyle (LPLFC), and the posterior lateral condylar angle (PLCA). RESULTS: Regardless of skeletal maturity, a DLM was associated with a greater inclination of the POLTP, lateralization of the LPLFC, and smaller PLCA (p < 0.001 for all compared to that of the control group). In the DLM group, the inclination of the AOLTP and the POLTP were significantly smaller (p < 0.001) and the LPLFC was more lateral (p < 0.001) in the closed physis group than in the open physis group. In the control group, the inclination of the POLTP was larger (p < 0.001) and the PLCA smaller (p = 0.019) in the open than in the closed physis group. CONCLUSIONS: We identified a characteristic knee morphology among patients with a complete DLM using MR imaging, which was observed before physeal closure and persisted after skeletal maturity was attained. We also noted lateralization of the LPLFC in the presence of a DLM, with an increase in lateralization with skeletal maturation. LEVEL OF EVIDENCE: Case-control study, III.