Varus Knee Research Articles

Lateral distal femoral condyle has more uniform cartilage wear in varus knee osteoarthritis

Bone resection is highly valued in total knee arthroplasty (TKA), but how to determine the amount of distal femur resection is still controversial. The purpose of this study was to explore how to use lateral condyle as a reference for distal femoral osteotomy in TKA. Magnetic resonance imaging (MRI) and Radiographic images from 118 nonarthritic subjects and 123 osteoarthritis (OA) subjects were used to assess the cartilage wear pattern of the distal femur in varus knees. Measurements were performed on three-dimensional reconstruction after virtual bone cutting. The difference between the resection amount of distal (0°) and posterior (90°) was calculated when the medial condyle was used as a reference in OA patients. The osteotomy amount on lateral was calculated in nonarthritic subjects when the medial condylar osteotomy was consistent with the thickness of the implants. In 43% of OA patients, there was > 1 mm difference between the 0° and 90° in medial condyle cartilage, and no difference was observed in lateral. When using medial condyle as a reference for osteotomy, there was a difference of 1.3 ± 0.56 mm between the resection amount of 0° and 90°, and the difference was 0.24 ± 0.27 mm when using lateral condyle. Statistical analysis showed that there was a linear correlation between the resection amount of lateral condyle and mechanical lateral distal femoral angle (mLDFA) in nonarthritic subjects (r = 0.845, p < 0.001). Lateral distal femoral condyle has more uniform cartilage wear in varus knee osteoarthritis. Using the lateral condyle as the reference for distal femoral osteotomy is more suitable for the cartilage wear pattern of the varus knee. The position of cutting guide can be adjusted by preoperative measurements of mLDFA.

The coronal alignment differs between two-dimensional weight-bearing and three-dimensional nonweight bearing planning in total knee arthroplasty.

The goal of this study is (1) to assess differences between two-dimensional (2D) weight-bearing (WB) and three-dimensional (3D) nonweight-bearing (NWB) planning in total knee arthroplasty (TKA) and (2) to identify factors that influence intermodal differences. Retrospective single-centre analysis of patients planned for a TKA with patient-specific instruments (PSI). Preoperative WB long-leg radiographs and NWB computed tomography were analysed and following radiographic parameters included: hip-knee-ankle angle (HKA) (+varus/-valgus), joint line convergence angle (JLCA), femorotibial subluxation and bony defect classified according to Anderson. Preoperative range of motion was also considered as possible covariate. Demographic factors included age, sex, and body mass index. A total of 352 knees of 323 patients (66% females) with a mean age of 66 ± 9.7 years were analysed. The HKA differed significantly between 2D and 3D planning modalities; varus knees (n = 231): 9.9° ± 5.1° vs. 6.7° ± 4°, p < 0.001; valgus knees (n = 121): -8.2° ± 6° vs. -5.5° ± 4.4°, p < 0.001. In varus knees, HKA (β = 0.38; p < 0.0001) and JLCA (β = 0.14; p = 0.03) were associated with increasing difference between 2D/3D HKA. For valgus knees, HKA (β = -0.6; p < 0.0001), JLCA (β = -0.3; p = 0.0001) and lateral distal femoral angle (β = -0.28; p = 0.03) showed a significant influence on the mean absolute difference. The coronal alignment in preoperative 3D model for PSI-TKA significantly differed from 2D WB state and the difference between modalities correlated with the extent of varus/valgus deformity. In the vast majority of cases, the 3D NWB approach significantly underestimated the preoperative deformity, which needs to be considered to achieve the planned correction when using PSI in TKA. Level III.

Comparing the Interobserver Reliability of 4 Methods Used to Measure Knee Laxity on Coronal Plane Stress Radiograph.

Varus and valgus knee stress radiographs provide valuable information in the pre- and postoperative evaluation of joint laxity in patients with multiligament knee injuries (MLKIs). To review the literature for described techniques of quantifying laxity on coronal stress radiographs of the knee and identify the most reliable method. Cohort study (diagnosis); Level of evidence, 3. A thorough literature search using the MEDLINE and Embase databases identified 4 studies with distinct methods for objectively measuring laxity on varus and valgus stress radiographs: Heesterbeek et al (2008), Jacobsen (1976), LaPrade et al (2004), and Sawant et al (2004). To compare these methods, 200 coronal plane stress radiographs from 50 patients with MLKIs were retrospectively reviewed from an MLKI database at a single institution. The amount of varus and valgus laxity on each radiograph was measured independently by 4 reviewers using each method. Intraclass correlation coefficients (ICCs) with 95% CIs were calculated to assess the interobserver reliability of each method overall and the varus and valgus measurements individually. For all 4 methods, the overall interobserver reliability was considered at least moderate. The method by Heesterbeek et al proved to have the highest interrater reliability in all domains-overall (ICC, 0.87 [95% CI, 0.85-0.90]), valgus (ICC, 0.83 [95% CI, 0.78-0.88]), and varus (ICC, 0.87 [95% CI, 0.83-0.90])-demonstrating good to excellent reliability both overall and in varus measurements and showing good reliability in valgus measurements. The method by Sawant et al demonstrated good reliability in valgus measurements. All other measures demonstrated moderate reliability. Available methods for measuring knee joint laxity on varus and valgus knee stress radiographs in patients with MLKIs demonstrated moderate to good interobserver reliability. The method described by Heesterbeek et al proved to have the highest reliability overall as well as in measurements on varus and valgus views individually.

Association Between Lumbar Spine Disorder and Genovarum: A Population-Based Cross-Sectional Study.

It is becoming increasingly important to study pathology at the knee and spine because of their role in causing pain and deformity in one another. Compression of the lumbar nerve root can disrupt innervation to the thigh muscles, cause an imbalance of muscle and result in varus deformity. In this study, we try to figure out the relation between lumbar spine disorders and genu varum and realize if lumbar spine disorders can cause varus deformity in a patient. In this cross-sectional study, the number of 53 patients with knee varus greater than 20 degrees who visited the orthopedic clinics of Rasoul Akram and Moheb Mehr hospitals affiliated to Iran University of Medical Sciences between 2020 and 2022 were investigated in terms of association with lumbar disorders. The demographic characteristics and clinical findings of the patients were recorded and collected using a checklist by referring to the patient's medical profiles. Radiographic findings were evaluated by referring to the imaging department and using the Pacs system. The diagnosis of the patients was based on the history and findings of the knee graph, which was measured with a goniometer to measure the knee angle. The frequency of lumbar disorders caused by pressure on the lumbar nerves in patients with genu varum deformity including canal stenosis, osteoarthritis, spondylolisthesis, and disc herniation was investigated. To investigate lumbar problems, patients' history and radiographic images as well as lumbosacral and knee MRI of patients were used. The mean age was 66.3 ± 7.66 years. 40 (75.5%) cases were female and 13 (24.5%) cases were male. Lumbar canal stenosis with 28(52.8%) and disc herniation with 32(60.4%) were the most common lumbar disorders in patients with knee varus more than 20 degrees. The mean age of patients with varus of more than 20 degrees with lumbar disorders was significantly higher than that of patients without lumbar disorders. (P: 0.001) There was no significant difference between gender distribution and lumbar disorders in patients with varus more than 20 degrees. Significant positive correlation between genu varum with lumbar canal stenosis (r: 0.53, P: 0.001), osteoarthritis (r: 0.38, P: 0.004), spondylolisthesis (r: 0.39, P: 0.002) and disc herniation (r: 0.46, P: 0.001) was reported2. An association between lumbar disorders and varus more than 20 degrees was found to be considerable.

Risk factors for varus knee osteoarthritis and their relationship with disease severity based on Kellgren-Lawrence classification.

To explore the hazard element of varus knee osteoarthritis (OA) and its relationship with Ailment severity based on the Kellgren-Lawrence classification. This study selected a cohort of patients who initially presented without clinical signs of arthritis and did not exhibit knee valgus or varus deformities when assessed from a hip-knee-ankle alignment perspective, focusing on the internal side. As the study progressed some individuals developed OA. Eligible participants were those who had undergone a standard whole lower extremity weight-bearing X-ray examination at our orthopedic outpatient clinic. The study period spanned from January 2021 to April 2022, and the selection criteria were strictly applied throughout this timeframe. Data on clinical and X-ray indices, including fibular head height, Kellgren-Lawrence grade, joint line convergence angle (JLCA), proximal medial tibial angle (MPTA), and Hip-knee-ankle angle, were collected from patients. The study included 23 grade 0, 22 grade I, 32 grade II, 32 grade III, and 97 grade IV Kellgren-Lawrence classified patients. Significant differences in age, gender, and BMI were observed across groups (all P<0.05). With increasing OA severity, fibular head height and MPTA decreased, while JLCA and Hip-knee-ankle angle increased significantly (all P<0.05). Patients with OA exhibited larger fibular head height and MPTA but smaller JLCA and Hip-knee-ankle angle than those without arthritis (all P<0.05). Logistic regression analysis confirmed age, fibular head height, MPTA, JLCA, and Hip-knee-ankle angle as independent risk factors for varus knee OA (all P<0.05). Additionally, there was a strong positive correlation between age and fibular head height with disease severity, but a strong negative correlation between Hip-knee-ankle angle and disease severity (all P<0.05). Patients with varus knee OA have larger fibular head height and MPTA than those without arthritis. Age, fibular head height, and Hip-knee-ankle angle are risk factors for the development of varus knee OA. The severity of arthritis and varus deformity increases with age and fibular head height.

Unicompartmental knee replacement combined with anterior cruciate ligament reconstruction provides comparable results to total knee replacement with no increased risk of complications.

There is controversy about the management of unicompartmental knee osteoarthritis (OA) in young, active patients with anterior cruciate ligament (ACL) insufficiency. This study compares the subjective, radiological, and functional results of total knee replacement (TKR) vs. combined medial unicompartmental knee replacement (UKR) with ACL reconstruction. Twelve patients suffering from medial OA and ACL deficiency with varus knee deformity and/or tibial slope<10° and absence of patellofemoral-related problems were eligible for combined UKR and ACL reconstruction (Group A). Twenty-six patients matched for age, male/female ratio and body mass index who received TKR in the same time frame were included as a control group (Group B). Oxford Knee Score (OKS), WOMAC index of osteoarthritis, Knee Osteoarthritis Outcome Score (KOOS), and routine X-rays were used for assessment. Ten years after surgery, the mean overall KOOS score, OKS, WOMAC index increased from preoperatively, showing a statistically significant difference (p<0.001). In terms of KOOS, OKS, or WOMAC scores at the most recent follow-up, there was no discernible difference between the groups (p=n.s.). Three years following surgery, one female patient in group A received revision TKR due to the lateral compartment's osteoarthritis developing and the patient's pain persisting. Concerning radiographic assessment, at the most recent follow-up (average 7.9years in group A and 8.8years in group B), there were no radiographic indications of implant loosening or proof of pathologic radiolucent lines. UKR combined with ACL restoration offers clinical and radiographic outcomes comparable to TKR 10years following surgery with no elevated risk of complications.

The Triple Varus Knee: A Case Presentation

Background: Knee instability due to posterior cruciate ligament (PCL) and posterolateral corner (PLC) deficiency is a devastating condition that negatively affects patient quality of life. This video presents the surgical management of a triple varus knee, including combined high tibial osteotomy (HTO), revision PCL and PLC reconstruction, and meniscus root repair. Indications: Combined HTO and revision PCL and PLC reconstruction is indicated for patients with previously failed PCL and PLC reconstruction in the setting of varus malalignment. Technique Description: The procedure begins with a medial opening-wedge biplanar HTO, which is fixed with a patient-specific locking plate. The PCL femoral tunnel is drilled via a low anterolateral portal, and the tibial insertion is debrided via a posteromedial portal. The medial meniscus is carefully freed from the posterior capsule, and 2 luggage tag sutures are placed through the posterior root. The PCL tibial tunnel and meniscus root tunnels are drilled via their respective guides. The meniscal sutures are passed through the tunnel but not fixed. An Achilles bone-block allograft is passed through the PCL tibial tunnel and fixed with suspensory fixation and an interference screw on the femoral side, while the tibial side is left free. A peroneal nerve neurolysis is performed. A fibular tunnel is drilled, and a semitendinosus allograft is whip-stitched on both sides and passed through the tunnel. A Beath pin is inserted into the femur, and the tunnel is over drilled. Both limbs of the graft are passed deep to the iliotibial band and into the tunnel. The tibial side of the PCL is fixed with an interference screw at 90° of knee flexion. The PLC grafts are fixed with an interference screw at 30° of knee flexion with slight valgus. The medial meniscus root sutures are tied over a button, with 60° of knee flexion. Screws from osteotomy fixation are replaced as needed. Results: Although outcomes following the combined procedure are lacking, good to excellent clinical outcomes have been reported in isolation following each procedure. Conclusion: A combination of HTO and revision PCL and PLC reconstruction should be considered for patients with persistent instability and/or pain in the setting of triple varus knee. 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.

Outcomes of combined ACL reconstruction and open wedge HTO: a systematic review

The deterioration of knee structures is enhanced by the anterior cruciate ligament (ACL) tear, which also can lead to osteoarthritis following a series of events. Additionally, untreated ACL insufficiency can lead to varus malalignment. ACL reconstruction can achieve the stability of the knee and restrict the osteoarthritis progression. High tibial osteotomy (HTO) is an intervention for the correction of varus malalignment in the lower extremity. HTO efficacy has been extended for the management of ACL-deficient varus knees. The combination of ACL reconstruction with HTO may result in better outcomes. The present review aimed at assessing the outcomes of ACL reconstruction and open wedge HTO combination. Scientific databases were explored for related studies published after 2015 and using a set of keywords for the searching process. Eligible criteria of the included studies were original articles written in the English language, reporting a combination of ACL reconstruction and open wedge HTO available for full text. A total of eight articles were included as they met the determined criteria. The total number of patients was 163 cases with an age range of 18 years and less than 70 years. The follow-up period was between 12 months and 10 years. The combination of ACL reconstruction and open wedge HTO resulted in favorable outcomes. However, there were few complications and a low rate of failure.

Open Wedge High Tibial Osteotomy for Treatment of Varus Knee in Adults Combined With Arthroscopic Evaluation

Open Wedge High Tibial Osteotomy for Treatment of Varus Knee in Adults Combined With Arthroscopic Evaluation

LATERAL EPICONDYLE SLIDING OSTEOTOMY IN KNEE ARTHROPLASTIES WITH VALGUS DEFORMITY.

To evaluate the efficacy and safety of sliding osteotomy of the lateral epicondyle in correcting rigid valgus deformity in knee arthroplasty. A retrospective study of patients undergoing total knee arthroplasty with lateral epicondyle sliding osteotomy between 2006 and 2018. The main outcome was the incidence of complications and adverse events. Secondary outcomes were Visual Analog Scale for Pain, varus stress test, and varus knee thrust during gait. 19 knees (19 participants) were included in the study. The mean follow-up was 4.2 years. There were no cases of infection or reoperation due to instability. Two participants (10.5%) had mild or moderate knee pain (VAS pain = 4.6 ± 1.9). Two arthroplasties (10.5%) had mild varus stress. No participant presented varus thrust. Sliding osteotomy of the lateral epicondyle allows fast and safe ligament balance of knee valgus deformities. Level of Evidence I, Case series.

ФУНКЦИОНАЛЬНАЯ ОЦЕНКА РЕЗУЛЬТАТОВ ПРОКСИМАЛЬНОЙ СЕГМЕНТАРНОЙ РЕЗЕКЦИИ МАЛОБЕРЦОВОЙ КОСТИ ПРИ ОСТЕОАРТРОЗЕ МЕДИАЛЬНОГО ОТДЕЛА КОЛЕННОГО СУСТАВА

Osteoarthritis (OA) of the knee joint is the commonest form of OA. It occurs commonly in the medial compartment because of a preponderance of varus knees. High tibial osteotomy, total knee replacement and unicompartmental knee replacement are technically demanding procedures, while proximal segmental fibular resection (PSFR) significantly relieves pain and improves joint function in knee osteoarthritis (OA). This study was conducted at the department of traumatology and orthopedics at the Belarusian state medical university. The objective of this study was to assess functional outcomes after PSFR and its correlation with bone mineral density. 23 patients with unicompartmental OA with varus deformity were included in the study. Inclusion criteria included patients with moderate-to-severe symptomatic medial unicom- partmental OA of the knee, who had an indication for a surgical procedure, and who were able to give informed consent for the surgery. Exclusion criteria included patients with posttraumatic knee OA or inflammatory joint disease and patients with a history of previous operations or fractures the primary outcome was measured by calculating the ratio of knee joint space. The secondary outcome measure was pain measured by the visual analog scale (VAS).

Preoperative radiographs underdiagnose the severity of lateral femoral and medial trochlear cartilage damage in varus osteoarthritis knees.

This study evaluated whether preoperative radiographs accurately predicted intra-articular cartilage damage in varus knees. The study assessed 181 knees in 156 patients who underwent total knee arthroplasty. Cartilage damage was graded by two examiners with the International Cartilage Repair Society classification; one used knee radiographs and the other used intraoperative photographs. It was then determined if this radiographic cartilage assessment over- or underestimated the actual damage severity. Knee morphological characteristics affecting radiographic misestimation of damage severity were also identified. The concordance rate between radiographic and intraoperative assessments of the medial femoral condyle was high, at around 0.7. Large discrepancies were found for the lateral femoral condyle and medial trochlear groove. Radiographic assessment underestimated cartilage damage on the medial side of the lateral femoral condyle due to a large lateral tibiofemoral joint opening and severe varus alignment {both r = -0.43}. Medial trochlear damage was also underdiagnosed, in cases of residual medial tibiofemoral cartilage and shallow medial tibial slope {r = -0.25 and -0.21, respectively}. Radiographic evaluation of knee osteoarthritis was moderately practical using International Cartilage Repair Society grades. Lateral femoral condyle and medial trochlear cartilage damage tended to be misestimated, but considering morphologic factors might improve the diagnostic rate.

Correction of Coronal Deformity and Intercompartmental Imbalance through Bone Resection.

This review discusses the correction of coronal deformity and intercompartmental imbalance through bone resection in total knee arthroplasty (TKA). To achieve functional knee balance, coronal, rotational, and sagittal alignment are critical to successful patient outcomes. Though variations in coronal alignment are debated as a correlate to positive results, advancements in utilizing implant position, alignment, and soft tissue balance to improve patient outcomes and function are an evolving discussion. This study draws upon existing literature, clinical studies, and surgical techniques related to TKA, including advancements in navigation and robotics. The study highlights the importance of individualized alignment strategies for varus and valgus knees. While mechanical neutral alignment has shown excellent long-term data, reevaluating the anatomic recreation of the patient's joint line obliquity is now being studied extensively. Sensor data and navigation systems contribute to improved outcomes and patient satisfaction. The evolution of navigation and robotics has led surgeons to achieve their target angles consistently and accurately; now, the discussion is around the most effective alignment targets. The classification of various phenotypes assists in the proposed starting points for implant position, but soft tissue tension is required in the input data to achieve global balance and stable motion. Each approach's advantages and limitations are considered. In conclusion, achieving optimal coronal alignment, joint line obliquity, and soft tissue balance is crucial for successful TKA outcomes. Personalized alignment philosophies, supported by three-dimensional data and sensor technology, are evolving to minimize critical errors and enhance functional results. Robotic assistance and future advancements in artificial intelligence and machine learning hold promise for further improving TKA outcomes in the quest for soft tissue stabilization.

Comparison of clinical, imaging and second-look arthroscopic outcomes between varus knee patients with and without preoperative tibial varus deformity after medial opening-wedge high tibial osteotomy

PurposeThis study aimed to compare the regeneration status of articular cartilage, clinical, and radiologic outcomes between varus knee patients with and without preoperative tibial varus deformity (PTVD) after medial opening-wedge high tibial osteotomy (OWHTO) MethodsVarus knee patients who had undergone OWHTO were divided into two groups according to preoperative medial proximal tibial angle (MPTA): a great varus (GV) group (MPTA <85°) and a mild varus (MV) group (85°≤preoperative MPTA <87°). The hip–knee–ankle (HKA) angle, weight-bearing line ratio (WBL%), MPTA, joint line convergence angle and joint line obliquity were measured. Second-look arthroscopy was undertaken 24 months after HTO. The Knee Society (KS) function score and knee score, and Lysholm score were used to evaluate the functional outcomes. All parameters were evaluated preoperatively and 24 months after HTO. ResultsThe GV group had greater varus than the MV group in HKA and WBL% before surgery, but greater valgus after surgery. The arthroscopic probe before HTO revealed the advanced chondral damage in the GV group and lighter chondral damage in the MV group. The regeneration of medial femoral condyle was considerably more frequent in the GV group (72.5%, 45/62) than in the MV group (50.0%, 27/54) (P = 0.030). No significant differences were observed in all functional outcomes preoperatively and 24 months after HTO. ConclusionThe extent of cartilage regeneration in patients without PTVD was inferior to that in those with PTVD, but the functional outcomes were comparable. OWHTO may be a treatment option in a selected subset of varus knee patients without PTVD.

"Boot Sign" of Anterior Femoral Condylar Resectional Shape during Total Knee Arthroplasty Is More Frequent in Asian Patients.

There is lack of intraoperative consensus on the distal femur anterior resected surface shape that allows reliable rotational alignment assessment during total knee arthroplasty (TKA). We aimed to evaluate the ratio and prevalence of anterior femoral resection surface intraoperatively. The study included 234 osteoarthritis patients with varus knees and not valgus knees or deformities. After conventional medial parapatellar approach, measured resection technique based on the mechanical axis of the femur and preoperative TEA-PCA angle on CT with anterior reference was used among all the patients. The anteroposterior (AP) lengths after distal femoral resection were measured as the femoral lateral AP (FLAP) and femoral medial AP (FMAP) lengths. Based on the medial (MD) and lateral condyle (LD) vertical distance ratios of the femur anterior resected surface, the groups were classified into "boot sign", "grand-piano", and "butterfly sign" groups. For comparison of the mean values, the data were assessed for normality with the Shapiro-Wilk test. One-way ANOVA with post hoc analysis using Tukey's honestly significant difference (HSD) test was used to compare the mean values among the groups. The correlations between the MD/LD and variables were analyzed using the Pearson correlation coefficient. Linear regression analyses were used to find the associated factors to the anterior femoral resection surface shape. Mean intraoperative femoral rotation and distal femoral cutting angles were 4.9° ± 1.2 and valgus 5.0° ± 0.7, respectively. Mean FLAP was 52.9 ± 4.2 mm. Mean MD/LD (0.61 ± 0.13) was lower than that of typical "grand-piano sign". The morphological shape incidence of the "boot sign" was 62.4%. In the "boot sign" group, the FLAP was found to be smaller than that in the other groups (52.4 ± 4.2 vs. 53.7 ± 4.2 vs. 54.9 ± 2.7; p = 0.02), while the intraoperative femoral rotation angle was found to be larger than in the other groups (5.0 ± 1.2 vs. 4.6 ± 1.1 vs. 4.7 ± 1.2; p = 0.039). The MD/LD-associated factors were FLAP, intraoperative femoral rotation, and distal femoral cutting angles (R2 = 0.268). The femur anterior resection surface shape in TKA was found in the "boot sign" rather than the "grand-piano sign" in Korean ethnics owing to an asymmetric morphology of femoral condyles. Ethnic differences, including distal femoral morphology, should be considered for assessment of the femoral rotation angle using the femur anterior resection surface shape.

Knee

The December 2023 Knee Roundup360 looks at: Obesity is associated with greater improvement in patient-reported outcomes following primary total knee arthroplasty; Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?; Robotic or manual total knee arthroplasty: a randomized controlled trial; Patient-relevant outcomes following first revision total knee arthroplasty, by diagnosis: an analysis of implant survivorship, mortality, serious medical complications, and patient-reported outcome measures using the National Joint Registry data set; Sagittal alignment in total knee arthroplasty: are there any discrepancies between robotic-assisted and manual axis orientation?; Tourniquet use does not impact recovery trajectory in total knee arthroplasty; Impact of proximal tibial varus anatomy on survivorship after medial unicondylar knee arthroplasty; Bone cement directly to the implant in primary total knee arthroplasty?; Maintaining joint line obliquity optimizes outcomes in patients with constitutionally varus knees.

Lateral subvastus approach to total knee arthroplasty: A novel surgical technique and retrospective review of 931 consecutive cases

BackgroundThe lateral muscle-sparing approach total knee arthroplasty (TKA) has been detailed and indicated selectively for severe valgus deformities. We present the largest, to date, consecutive series of lateral subvastus TKAs and we hypothesize that preoperative alignments would demonstrate no differences in range of motion (ROM), knee society scores (KSS), kneeling ability, patient satisfaction, or complications. Materials and methodsThis retrospective study examined 931 primary TKAs in 824 patients performed through the lateral subvastus approach with one to two years follow-up. All primary TKAs performed between July 2020 and February 2022 were included. We used descriptive statistics, chi-squares, and analysis of variance (ANOVA) to examine the cohort. Significance was set to p < .05. ResultsPatient's ROM significantly improved by six weeks, (1–117°, P < .05) with continued improvement by one-year, (0–121, P < .05) with no significant differences in alignment in extension, (P = .142) or flexion, (P = .253). There were also no significant differences in alignment in KSS scores at six-weeks, (P = .635), three-months, (P = .829), six-months, (P = .836), one-year, (P = .641) or two-years, (P = .776). There were no significant differences in kneeling ability, (P = .563), and 85% of patients reported being able to kneel. There were no differences in patient satisfaction, (P=.436), and 90% of patients reported being satisfied. There was a low 8% complication rate in this cohort. Neutral and varus knees were less likely than valgus knees to develop deep vein thrombosis (DVT; P < .05) or have a medial collateral ligament (MCL) injury (P < .05). ConclusionsPatients with varus, valgus, and neutral knees had similar outcomes when using a lateral subvastus approach to TKA in ROM and KSS that were stable over two years with similar kneeling ability and satisfaction. There was a low incidence of complications with neutral and varus knees at the lowest risk. A lateral subvastus approach to TKA can be safe and effective for all knee deformities.

THE MECHANICAL REGULATION OF SEMA3A IN PATIENT SYNOVIAL FLUID WITH CHRONIC KNEE VARUS MALALIGNMENT

AbstractOBJECTIVEKnee varus malalignment increases medial knee compartment loading and is associated with knee osteoarthritis (OA) progression and severity1. Altered biomechanical loading and dysregulation of joint tissue biology drive OA progression, but mechanistic links between these factors are lacking. Subchondral bone structural changes are biomechanically driven, involve bone resorption, immune cell influx, angiogenesis, and sensory nerve invasion, and contribute to joint destruction and pain2. We have investigated mechanisms underlying this involving RANKL and alkaline phosphatase (ALP), which reflect bone resorption and mineralisation respectively3 and the axonal guidance factor Sema3A. Sema3A is osteotropic, expressed by mechanically sensitive osteocytes, and an inhibitor of sensory nerve, blood vessel and immune cell invasion4. Sema3A is also differentially expressed in human OA bone5.HYPOTHESIS: Medial knee compartment overloading in varus knee malalignment patients causes dysregulation of bone derived Sema3A signalling directly linking joint biomechanics to pathology and pain.METHODSSynovial fluid obtained from 30 subjects with medial knee OA (KL grade II-IV) undergoing high tibial osteotomy surgery (HTO) was analysed by mesoscale discovery and ELISA analysis for inflammatory, neural and bone turnover markers. 11 of these patients had been previously analysed in a published patient-specific musculoskeletal model6 of gait estimating joint contact location, pressure, forces, and medial-lateral condyle load distribution in a published data set included in analyses. Data analysis was performed using Pearson's correlation matrices and principal component analyses. Principal Components (PCs) with eigenvalues greater than 1 were analysed.RESULTSPC1 (32.94% of variation) and PC2 (25.79% of variation) from PCA analysis and correlation matrices separated patients according to correlated clusters of established inflammatory markers of OA pain and progression (IL6/IL8, r=0.754, p&lt;0.001) and anti-inflammatory mediators (IL4/IL10, r=0.469, p=0.005). Bone turnover marker ALP was positively associated with KL grade (r=0.815, p=0.002) and negatively associated with IL10 (r=−0.402, p=0.018) and first peak knee loading pressures (r=−0.688, p=0.019). RANKL was positively associated with IL4 (r=0.489, p=0.003). Synovial fluid Sema3A concentrations showed separate clustering from all OA progression markers and was inversely correlated with TNF-α (r=−0.423, p=0.022) in HTO patients. Sema3A was significantly inversely correlated with total predicted force in the medial joint compartment (r=−0.621, p=0.041), mean (r=−0.63, p=0.038) and maximum (r=−0.613, p=0.045) calculated medial compartment joint pressures during the first phase and mean (r=−0.618, p=0.043) and maximum (r=−0.641, p=0.034) medial compartment joint pressures during midstance outputs of patient-specific musculoskeletal model.CONCLUSIONSThis study shows joint inflammatory status and mechanical overloading influence subchondral bone-remodelling. Synovial Sema3A concentrations are inversely correlated to patient-specific musculoskeletal model estimations of pathological medial overloading. This study reveals Sema3A as a biological mediator with capacity to induce OA pain and disease progression that is directly regulated by gait mechanical loading.Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Constitutional alignment predicts medial ligament balancing in mechanically aligned total knee arthroplasty for varus knees.

The aim of this study was to identify if constitutional alignment and preoperative radiologic parameters determined whether medial gap balancing was required in mechanically aligned total knee arthroplasty (TKA). Two hundred and sixty three patients with 394 consecutive knees who underwent primary TKAs were retrospectively analysed in this study. Selective sequential multiple needle puncturing (MNP) was performed for medial ligament balancing when required. Constitutional alignment, which was determined using the Coronal Plane Alignment of the Knee (CPAK) classification, as well as preoperative and postoperative radiologic parameters was evaluated to identify factors which predicted the need for MNP. One hundred and fifty eight (40.1%) knees required medial ligament balancing with MNP. Patients who required MNP during surgery had significantly more constitutional varus, more varus preoperative mechanical Hip-Knee-Ankle angle (mHKA), smaller preoperative medial proximal tibial angle (MPTA) and a larger change in mHKA and MPTA after surgery than those who did not. Patients with constitutional varus also had a higher incidence of having had MNP to both anterior and posterior superficial medial collateral ligament (sMCL) fibres. There was no significant difference in preoperative lateral distal femoral angle (LDFA), posterior tibial slope (PTS) and varus-valgus difference (VVD) between groups. Ligament balancing using MNP was determined by constitutional alignment rather than medial soft tissue contracture. Patients with constitutional varus who had a larger medio-lateral gap difference in extension also had a higher incidence of having had MNP to both anterior and posterior sMCL fibres. Retrospective comparative study, level IV.

Preserving primary medial static stabilizer ligaments achieves physiological knee kinematics in total knee arthroplasty

PurposeAs postoperative knee instability has been reported to be one of the critical reasons for early failure in total knee arthroplasty (TKA), obtaining optimal knee stability—especially in medial—was indispensable for successful TKA. We hypothesized that preserving medial soft tissue structures was the key to maintain physiological medial knee stability. Thus, TKAs with preserving primary medial static stabilizer ligaments technique were performed, and the postoperative knee kinematics was evaluated. MethodsPrimary knee osteoarthritis patients with varus knee deformity and planed for primary TKA were enrolled. However, patients with severe varus knee deformities, valgus knee deformities, and rheumatoid arthritis were excluded. TKAs were performed by removing medial femoral and tibial osteophytes; however, the primary medial static stabilizer ligaments—the superficial medial collateral ligament (MCL), deep MCL, and posterior oblique ligament—were not released. The cruciate-retaining (CR), posterior-stabilized (PS), and medial-pivot (MP) inserts were implanted, and the knee kinematics was measured. These data were statistically analyzed using analysis of variance. The institutional review board approved the study. ResultsFrom full extension to maximum flexion, the lateral femoral condyle moved backward, greater than the medial femoral condyle, and consequently the femur external rotated on the tibia. These kinematics patterns were shown in CR, PS, and MP groups. ConclusionAs the knee kinematics of CR and PS are similar to that of MP, which has been reported to demonstrate physiological knee kinematics, preserving primary medial static stabilizer ligaments technique could potentially preserve physiological knee kinematics.