Navigated Unicompartmental Knee Arthroplasty: A Different Perspective

BackgroudAnteromedial osteoarthritis is a recognized indication for unicompartmental knee arthroplasty (UKA). Favorable postoperative outcomes largely depend on proper patient selection, correct implant positioning, and limb alignment. Computer navigation has a proven value over conventional systems in reducing mechanical errors in total knee arthroplasty (TKA). However, the lack of strong evidence impedes the universal use of computer navigation technology in UKA. Therefore, this study was proposed to investigate the accuracy of component positioning and limb alignment in computer navigated UKA and to observe the role of navigation in proper patient selection.MethodsA total of 50 knees (38 patients) underwent computer navigated UKA between 2016 and 2018. All operations were performed by the senior surgeon using the same navigation system and implant type. The navigation system was used as a tool to aid patient selection: knees with preoperative residual varus > 5° on valgus stress and hyperextension > 10° were switched to navigated TKA. We measured the accuracy of component placement in sagittal and coronal planes on postoperative radiographs. Functional outcomes were also evaluated at the final follow-up (a minimum of 16 months).ResultsNine patients had tibia vara and 14 patients had preoperative hyperextension deformity. We observed coronal outliers for the tibial component in 12% knees and for the femoral component in 10% knees. We also observed sagittal outliers for the tibial component in 14% knees and for the femoral component in 6% knees. There was a significant improvement in the functional score at the final follow-up. On multiple linear regression, no difference was found in functional scores of knees with or without tibia vara (p = 0.16) and with or without hyperextension (p = 0.25).ConclusionsOur study further validates the role of computer navigation in desirable implant positioning and limb alignment. We encourage use of computer-assisted navigation as a tool for patient selection, as it allows intraoperative dynamic goniometry and provides real-time kinematic behavior of the knee to obviate pitfalls such as significant residual varus angulation and hyperextension that predispose early failure of UKA.     

Combined Proximal Tibial Osteotomy for Adult Kashin–Beck Disease with Severe Varus Knee Osteoarthritis: Case Report and Literature Review

BackgroundKashin–Beck disease (KBD) is an endemic, chronic osteoarthropathy that seriously affects joint function and can lead to severe knee deformity. Osteotomy is considered to be one of the effective methods for the treatment of this disease. Therefore, we designed a novel type of osteotomy named combined proximal tibial osteotomy (CPTO), which combines the characteristics of opening‐wedge high tibial osteotomy and tibial condylar valgus osteotomy.Case presentationWe report the case of a 48‐year‐old male with knee pain and varus deformity who was diagnosed with KBD and varus knee osteoarthritis (Kellgren–Lawrence stage IV). Considering the patient''s relatively young age, a varus deformity of the right knee of 16.79°, and an intra‐articular instability, we performed a CPTO treatment. In this procedure, we performed an L‐shaped osteotomy from the medial edge of the proximal tibia to the intercondylar eminence and an osteotomy from the medial side of the proximal tibia to the lateral side through the same incision, to adjust the leg alignment and the congruity of the joint by valgus correction. At 29 months follow‐up, this patient achieved satisfactory results, with a varus right knee of 2.87°. There was significant improvement in his right knee function, pain, and joint stability.ConclusionsCPTO may be an acceptable treatment for KBD patients with severe knee varus deformity and intra‐articular instability. It can be considered as an alternative treatment, especially for patients with advanced osteoarthritis needing knee preservation.     

Total Knee Arthroplasty Using Adjusted Restricted Kinematic Alignment for the Treatment of Severe Varus Deformity: Technical Note

ObjectiveTo describe a new alignment technique of adjusted restricted kinematic alignment (arKA) for the treatment of severe varus deformity in total knee arthroplasty.MethodsThree female patients (three severe varus knees) who underwent navigation‐assisted total knee arthroplasty (TKA) using arKA from April 2020 to September 2020 were included in this study, with an average age of 71.33 years (range, 61 to 80 years). General anesthesia was given to all patients. Intraoperative observations including tibia resection angle, frontal femoral angle, axial femoral angle, medial and lateral gap in the extension and flexion positions and joint line translation were recorded. Also, operation duration and drainage volume were recorded. Radiographic parameters including the mechanical axis (α), coronal femoral component angle (β), coronal tibial component angle (γ), sagittal femoral component angle (δ), tibial posterior slope angle (ε), femoral‐patella angle (θ), and femoral notching were assessed. Clinical evaluation was performed using the Hospital for Special Surgery (HSS) Score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score. Both individual and mean measurement data were displayed.ResultsThe mean tibial resection was 4.00° varus (range, 3° to 5°), and the mean frontal femoral angle was 3.67° varus (range, 3° to 4°) in extension. The flexion lateral gap was wider than the medial gap with a mean laxity of 1.34 mm. Moreover, the mean axial femoral angle was 2.67° external (range, 0° to 6°) in flexion, and the mean joint line translation was 1.00 mm proximal (range, 0 to 3 mm). In addition, the mean preoperative mechanical axis was 156.22° (range, 153.65° to 158.90°) and the mean postoperative mechanical axis was 174.04° (range, 173.83° to 174.17°) with a mean correction of 17.82°. The mean femoral angle was 92.60° (range, 91.29° to 93.30°) and the mean tibial angle was 86.95° (range, 86.83° to 87.04°) in coronal plane. The HSS score improved from an average of 46.67 points (range, 42 to 51) preoperatively to 83.67 points (range, 81 to 86) at 3 months postoperatively. The mean WOMAC score was 16.33 points at 3 months postoperatively.ConclusionsThe new alignment technique of arKA aims to balance the flexion and extension gap without extensive releases of soft tissue and restore the native pre‐arthritic alignment, may be a promising alignment strategy for treating severe varus deformity. However, further study and comparison with other alignment techniques is needed.     

Effects of Surgeon Handedness on the Outcomes of Unicompartmental Knee Arthroplasty: A Single Center's Experience

ObjectiveSurgeon handedness has been widely discussed in operative surgery, and could cause clinical discrepancy. However, few studies have reported the effect of handedness on unicompartmental knee arthroplasty (UKA). Based on our clinical observation and case analysis, we aimed to find out the effects of surgeon handedness on UKA.MethodsWe retrospectively studied 94 UKA procedures performed by one right‐handed surgeon from January 2017 to December 2018 at a single medical center. The cases were divided into two groups by operation side (49 L‐UKAs and 45 R‐UKAs). Preoperative demographic data were collected. Imaging parameters (femorotibial and hip‐knee‐ankle angles and tibial‐plateau retroversion) and joint function scores (Knee Society Score [KSS] and Oxford Knee Score [OKS]) were recorded. Patients were followed up regularly and Forgotten Joint Score (FJS) was calculated at the last follow‐up. All data were compared between the two groups with independent‐samples t‐test, and paired t‐test was used for intragroup comparisons.ResultsThe average follow‐up was 26.7 ± 3.2 months. The average patient age was 63.5 ± 9.0 years and the average body mass index was 26.89 ± 3.43 kg/m². There was no significant group difference in any preoperative characteristic. Both the KSS and OKS improved significantly after surgery (p < 0.05). No significant group difference was found between the KSS or OKS at any follow‐up visit. The varus or valgus of tibial component was 3.57 ± 1.42° on the left side and 3.19 ± 1.56° on the right side (p = 0.45). The varus or valgus of femoral component was 7.81 ± 2.43° in patients undergoing L‐UKA and 7.05 ± 2.90° in those undergoing R‐UKA (p = 0.04). No statistical differences were found in outliers of component orientation on both sides. The femorotibial and hip‐knee‐ankle angles improved significantly in both groups, and there was no significant group difference in either lower limb alignment or tibial‐plateau retroversion. The complication rate was 8.16% (4/49) in the L‐UKA group and 6.67% (3/45) in the R‐UKA group. There was no correlation between prosthesis orientation and early joint function score.ConclusionsSurgeon handedness may cause a worse prosthetic orientation on femoral side during surgeon''s non‐dominant UKA, and surgeons should be cautious of bone resection and prosthesis implantation. However, radiographic difference did not bring variations on short‐term clinical outcomes or lower limb alignment.     

膝关节内侧固定平台单髁假体放置位置优化的有限元分析

目的探讨股骨组件及胫骨组件冠状面位置变化对股骨及胫骨生物力学的影响。方法取1名汉族男性志愿者的左侧膝关节CT及MRI图像,建立正常膝关节三维有限元模型(finite elemental model,FEM)。设计股骨组件及胫骨组件内翻6°、内翻3°、0°、外翻3°、外翻6°,组合成25个膝内侧单髁置换FEM。沿股骨机械轴加载1000 N载荷,观察von Mises云图应力分布,测量外侧间室载荷比例,测量胫骨组件下方松质骨及内侧皮质骨、聚乙烯衬垫上表面、外侧间室股骨软骨高接触应力值。将与中立位(胫骨及股骨假体内外翻0°、胫骨假体后倾5°)比较有统计学意义的指标通过散点图标识,找出点项目密集区和稀疏区,比较两区有统计学意义的项目数量,确定股骨组件、胫骨组件优化位置。结果股骨组件0°位放置时,胫骨从内翻6°至外翻6°各组合的胫骨组件下方松质骨高接触应力差异无统计学意义;胫骨组件0°位放置时,股骨组件内翻6°、外翻6°组件下方松质骨高接触应力值与中立位比较增加(9.21±3.38)MPa和(9.08±4.13)MPa(P<0.05)。股骨、胫骨组件从内翻6°至外翻6°变化时,胫骨下方内侧皮质骨高接触应力值逐渐下降(P<0.05)。股骨组件0°位放置时,胫骨组件从内翻6°至外翻6°各组合聚乙烯衬垫上表面高接触应力值的差异无统计学意义;胫骨组件0°位放置时,股骨组件内翻6°、外翻6°组与中立位组比较分别增加(2.88±2.53)MPa和(3.47±2.86)MPa(P<0.05);股骨及胫骨组件从内翻6°至外翻6°变化时,外侧间室载荷比例及外侧间室股骨软骨高应力值逐渐下降(P<0.05)。稀疏区(股骨或胫骨从内翻3°至外翻3°的所有组合的集合)有统计学意义的指标比例(2.8%,1/36)明显小于密集区(去除稀疏区以外的所有组合的集合)的比例(57.8%,37/64),差异有统计学意义(χ^2=29.61,P<0.001)。结论在下肢力线正常、关节线不变的条件下,膝关节内侧固定平台单髁假体放置位置为股骨组件、胫骨组件内翻、外翻角度不宜超过3°。     

Three-dimensional finite element analysis of unicompartmental knee arthroplasty--the influence of tibial component inclination.

Aseptic loosening and failure of a tibial component are recognized problems in unicompartmental knee arthroplasty (UKA). Excessive stress on the supporting cancellous bone is thought to contribute to the loosening and failure. Of factors that could influence supporting cancellous bone stresses, we focused on the inclination of a unicompartmental tibial component by analyzing the effect of coronal plane and sagittal plane inclination. Detailed geometrically accurate, three-dimensional finite element models were constructed from computed tomography (CT) data of a typical adult male proximal tibia. The material properties for the models were obtained directly from the CT data to simulate the inhomogeneous distribution of cancellous bone properties. Placing the component in slight valgus inclination in the coronal plane reduced the cancellous bone stresses. Posterior inclination in the sagittal plane caused a moderate increase in the stresses. Our results suggest that slight valgus inclination of a UKA tibial component may be preferable to varus or square inclination in the coronal plane. An excessive posterior slope of a tibial component should be avoided.     

Flexion Tibial Plateau Fractures: 3‐dimensional CT Simulation‐based Subclassification by Injury Pattern

ObjectiveTo identify different injury patterns of flexion tibial plateau fractures (FTPFs) with 3D CT simulation technology. The association between these hypothesized injury patterns and concomitant injuries was also investigated.MethodsThe tibial plateau fracture cases of 297 patients consecutively treated at our trauma center from August 2016 to December 2018 were reviewed retrospectively. A total of 108 patients with FTPFs were enrolled. 3D CT simulation technology was used to reconstruct the position of the knee joint at the time of tibial plateau fracture. The 3D segments for the tibia and femur were created separately, the tibial 3D segment was aligned with the articular surface of the femoral condyle, and then the corresponding injury patterns were deduced. The magnitudes of translation and rotation incurred after the segments were repositioned were calculated by Mimics software. The associations between the hypothesized injury patterns and concomitant injuries were compared.ResultsFTPFs were classified into two groups according to the fracture region: unicondylar FTPFs (type I) and bicondylar FTPFs (type II). According to the injury patterns simulated in this study, these two types of FTPFs were further subclassified into five subgroups. Type I FTPFs were categorized into two subtypes based on the degree of rotation in the coronal plane (varus < 0°; valgus > 0°): pure flexion‐varus fractures (type IA, −10.23° ± 2.11°, 3.7%, 4/108) and pure flexion‐valgus fractures (type IB, 11.54° ± 2.63°, 26.9%, 29/108). Type II FTPFs were divided into three subgroups based on the degree of rotation in the axial plane (internal rotation >10°; flexion‐neutral −10° to 10°; external rotation <−10°): flexion‐neutral fractures (type IIA, 2.01° ± 3.43°, 13.0%, 14/108), flexion‐internal rotation fractures (type IIB, 23.66° ± 6.17°, 35.2%, 38/108) and flexion‐external rotation fractures (type IIC, −16.23° ± 4.27°, 21.3%, 23/108). The incidence of posterolateral quadrant collapse fractures among type IIB fractures was significantly increased relative to that of type IIC fractures (P < 0.001). The incidence of posterolateral quadrant split fractures, anterolateral quadrant fractures and proximal fibular fractures among type IIC fractures was significantly higher than that among type IIB fractures (P < 0.001). The number of these concomitant injuries significantly differed between type IIB and type IIC fractures (P < 0.001).Conclusion3D CT simulation‐based subclassification according to the pattern of injury can help surgeons better understand FTPFs and select an appropriate treatment strategy.     

Adequate Positioning of the Tibial Component Is Key to Avoiding Bearing Impingement in Oxford Unicompartmental Knee Arthroplasty

BackgroundBearing dislocation is a serious complication of unicompartmental knee arthroplasty (UKA) with the Oxford knee prosthesis equipped with a mobile bearing. We aimed to clarify the extent of intraoperative movement of the mobile bearing and its relationship with the positioning of prosthesis components in patients undergoing Oxford UKA.MethodsThis retrospective study included 50 patients (50 knees) who underwent Oxford UKA for anteromedial osteoarthritis or osteonecrosis of the knee. Intraoperative bearing movement was assessed at various angles of knee flexion (0°, 30°, 60°, 90°, and 120°). We stratified patients according to the extent of bearing movement posteriorly during intraoperative knee flexion, with or without contacting the lateral wall of the tibial component (with contact, 20 knees; without contact, 30 knees). Postoperative radiographic evaluations were conducted at 1 week postoperatively to assess the positional parameters of the tibial and femoral components (varus/valgus alignment, rotation, mediolateral position). Clinical evaluations were conducted at 1 year postoperatively (maximum flexion angle, Oxford Knee Score).ResultsAbnormal intraoperative movement of the mobile bearing resulting in contact with the lateral wall of the tibial component was associated with a significantly more medial position and external rotation of the tibial component, as well as poorer improvement in knee flexion angle at 1 year postoperatively.ConclusionIn Oxford UKA recipients, the bearing may impinge on the lateral wall of the tibial component during flexion above 60° if the tibial component is placed too medially or exhibits pronounced external rotation, which may limit knee function improvement postoperatively.     

Valgus Subsidence of the Tibial Component Caused by Tibial Component Malpositioning in Cementless Oxford Mobile-Bearing Unicompartmental Knee Arthroplasty

BackgroundValgus subsidence (VS) of the tibial component is a rare complication of unicompartmental knee arthroplasty (UKA), and surgeons might consider revision surgery. The present study aimed to identify the factors related to VS of the tibial component after cementless Oxford mobile-bearing UKA.MethodsThe study included 120 patients who underwent Oxford mobile-bearing UKA using a cementless tibial component in our center between September 2015 and September 2016. Six showed VS of >2° after surgery. Patients were stratified into 2 groups according to the occurrence of VS of the tibial component (VS group, n = 6; no-subsidence group, n = 114). Postoperative radiographic evaluations were conducted to assess the varus/valgus alignment, rotation, and mediolateral position of the tibial and femoral components. The Oxford Knee Score (OKS) was assessed at 3, 6, and 12 months postoperatively. Positional parameters and sequential change in OKS were compared between the two groups using unpaired t-test (P < .05, statistically significant).ResultsAt 3 months postoperatively, an average VS of 3.4° in the VS group was observed, with a significant decrease in OKS. VS was associated with a significantly more medial position and external rotation of the tibial component. After 3 months, VS stopped, and the OKS gradually improved without revision surgery.ConclusionsVS might be caused by the malpositioning of the tibial component. VS of the tibial component after UKA appears to stop, with simultaneous pain relief, even without revision after 3 months postoperatively.     

Correction of coronal plane deformities around the knee using a tension band plate in children younger than 10 years

Background:

Guided growth through temporary hemiepiphysiodesis has gained acceptance as the preferred primary treatment in treating pediatric lower limb deformities as it is minimally invasive with a lesser morbidity than the traditional osteotomy. The tension band plate is the most recent development in implants used for temporary hemiepiphysiodesis. Our aim was to determine its safety and efficacy in correcting coronal plane deformities around the knee in children younger than 10 years.

Materials and Methods:

A total of 24 children under the age of 10 were operated for coronal plane deformities around the knee with a single extra periosteal tension band plate and two nonlocking screws. All the children had a pathological deformity for which a detailed preoperative work-up was carried out to ascertain the cause of the deformity and rule out physiological ones. The average age at hemiepiphysiodesis was 5 years 3 months (range: 2 years to 9 years 1 month).

Results:

The plates were inserted for an average of 15.625 months (range: 7 months to 29 months). All the patients showed improvement in the mechanical axis. Two patients showed partial correction. Two cases of screw loosening were observed. In the genu valgum group, the tibiofemoral angle improved from a preoperative mean of 19.89° valgus (range: 10° valgus to 40° valgus) to 5.72° valgus (range: 2° varus to 10° valgus). In patients with genu varum the tibiofemoral angle improved from a mean of 28.27° varus (range: 13° varus to 41° varus) to 1.59° valgus (range: 0-8° valgus).

Conclusion:

Temporary hemiepiphysiodesis through the application of the tension band plate is an effective method to correct coronal plane deformities around the knee with minimal complications. Its ease and accuracy of insertion has extended the indication of temporary hemiepiphysiodesis to patients younger than 10 years and across a wide variety of diagnosis including pathological physis, which were traditionally out of the purview of guided growth.     

An Approach to Intraoperatively Identify the Coronal Plane Deformities of the Distal Tibia When Treating Tibial Fractures with Intramedullary Nail Fixation: a Retrospective Study

ObjectiveTo develop a new approach to intraoperatively identify the presence of coronal plane deformities (both valgus and varus) when treating tibial fractures with closed reduction and intramedullary nail fixation.MethodsA retrospective analysis was conducted by enrolling 33 consecutive patients with tibial fractures who received closed reduction and intramedullary nail fixation from January 2018 to January 2019 at our trauma center. Out of the 33 patients, 23 were males and 10 were females and the average age was 41 years (ranging 22 to 69 years of age). Standard anteroposterior and lateral preoperative radiographs were routinely performed. After intraoperatively inserting the tibial intramedullary nail through the standard entry point, the parallel relationship between the distal horizontal interlocking screw and the tibiotalar joint surface on the anteroposterior fluoroscopy was used to determine the occurrence of valgus or varus deformities of the distal tibial fragment. Radiographic and clinical outcomes were analyzed using the average interval from injury to surgery, the lateral distal tibial angle (LDTA) of the unaffected and affected sides, complications and the Olerud–Molander ankle score.ResultsAll 33 patients were postoperatively followed for 13 to 25 months (mean 18.7 months). The fractures achieved bone union at an average of 4.3 months (ranging from 3 to 6 months). The total complication rate was 60.6% (20 cases), including four cases that showed deep vein thrombosis, one case showing an infection and delayed union and 15 cases showing slight to moderate anterior knee pain. The postoperative LDTA of the unaffected side measured 87.3° to 89.6 ° (average 88.7° ± 0.8°), and the LDTA of the affected side was 87.5° to 90.4° (average 88.9° ± 1.1°). There was no significant difference between the unaffected and affected sides (t = −1.865, P = 0.068). The intraoperative measurement indicated six cases of valgus angulation and three cases of varus angulation deformities, and all deformities were corrected during surgery. According to the Olerud–Molander ankle score, clinical outcomes demonstrated 22 excellent cases, eight good cases, two fair cases, and one poor case 12 months after surgery.ConclusionThe parallel relationship between the distal horizontal interlocking screw and tibiotalar joint surface on intraoperative anteroposterior films were able to determine the onset of valgus or varus angulations of the distal tibial fragment in the fracture zone after the tibial intramedullary nail was inserted through the standard entry point.     

Is Flexion Gap Rectangular in Native Indian Knees? Results of an MRI Study

BackgroundThe purpose of this study was to evaluate the flexion-gap of the native knees in the normal population and to assess any gender-specific variations in the flexion gap of the knees.MethodsA total of 50 normal asymptomatic volunteers with normal knee radiographs were selected for MRI of the knee. The left knee was scanned in an open MRI using a T1-weighted sequence. Imaging was performed in neutral, passive varus and valgus stress at 90° of knee flexion by placing custom-made blocks on a special board consecutively below the distal part of the leg.ResultsThe study population consisted of 26 males and 24 females with a mean age of 25.77 years. Under varus stress, the mean lateral flexion gap increased to 9.28 ± 1.53 mm and under valgus stress, the mean medial flexion gap increased to 2.75 ± 1.22 mm from neutral. The increase in the flexion gap on the lateral side was 5.28 ± 1.79 mm, which was significantly higher compared to that on the medial side. In gender-specific analysis, the mean lateral flexion gap was 10.21 mm in females and 8.46 mm in males under varus stress.ConclusionThe findings of the study indicate that the lateral soft tissues are more lax compared to the medial soft tissue structures and this laxity is higher in females as compared to males. The study provides evidence of the existing physiological variations of these soft tissue structures resulting in a trapezoidal flexion gap in the native knees rather than the recommended rectangular gap.     

The Permissive Safe Angle of the Tibial Tunnel in Transtibial Posterior Cruciate Ligament Reconstruction: A Three‐Dimensional Simulation Study

ObjectiveTo determine the permissive safe angle (PSA) of the tibial tunnel in transtibial posterior cruciate ligament (PCL) reconstruction based on a three‐dimensional (3D) simulation study.MethodsThis was a computer simulation study of transtibial PCL reconstruction using 3D knee models. CT images of 90 normal knee joints from 2017 to 2020 were collected in this study, and 3D knee models were established based on CT data. The tunnel approaches were subdivided into the anterior 1/3 of the anteromedial tibia (T1), middle 1/2 of the anteromedial tibia (T2), the tibial crest (T3), anterior 1/3 of the anterolateral tibia (T4), middle 1/2 of the anterolateral tibia (T5). Five tibial tunnels (T1–T5) were simulated on the 3D knee models. The PSAs, in different tibial tunnel approaches were measured, and subgroup analyses of sex, age and height were also carried out.ResultsThe mean PSAs of the tibial tunnels with 5 different approaches (T1–T5) were 58.49° ± 6.82°, 61.14° ± 6.69°, 56.12° ± 7.53°, 52.01° ± 8.89° and 49.90° ± 10.53°, respectively. The differences of the mean PSAs between the anteromedial and anterolateral approaches were significant (P < 0.05). However, there was no significant difference of the mean PSA value between the two anteromedial tibial tunnel approaches (T1–T2) (P > 0.05), as well as between the two anterolateral tibial tunnel approaches (T4–T5). The patient''s anthropomorphic characteristics of sex, age, and height were not associated with the PSAs.ConclusionsThe PSA varied with the anteromedial, tibial crest and anterolateral approaches for transtibial PCL reconstruction, and surgeons should limit the PCL drill guide by referring to the specific PSA for different surgical approaches.     

The Coronal Plane High Tibial Osteotomy. Part 1: A Clinical and Radiographic Analysis of Intermediate Term Outcomes

The coronal plane high tibial osteotomy is a novel technique that is used to treat tibiofemoral malalignment. The authors hypothesize that the coronal plane high tibial osteotomy is (1) efficacious in treating both varus and valgus tibiofemoral malalignment; (2) does not alter the slope of the proximal tibia; and (3) does not alter the relationship between the patella and tibial tubercle. A retrospective review of 25 patients with tibiofemoral malalignment (19 varus/6 valgus) treated with a coronal plane osteotomy with a minimum of 2-year follow-up was performed. A Kaplan–Meyer survival curve was performed using knee arthroplasty and a Hospital for Special Surgery (HSS) knee score <70 as failure criteria. The Insall–Salvati ratio and the proximal tibial slope were measured. A p value of 0.05 was considered significant. At 60-month follow-up, knees with initial varus malalignment had an 84% survival rate using both knee arthroplasty and the HSS score as endpoints. Knees with initial valgus malalignment had an 84 and 60% survival rate using knee arthroplasty and the HSS score as endpoints, respectively. There was no statistically significant change in the Insall–Salvati ratio and proximal tibial slope after coronal plane osteotomy. The coronal plane osteotomy is efficacious in treating varus and valgus tibiofemoral malalignment and does not alter the patellar–tibial tubercle relationship or the posterior tibial slope [case series (level of evidence: IV)].     

Treatment of 10-mm-Deep or Greater Uncontained Tibial Bone Defects in Primary Total Knee Reconstruction without Metal Augmentation: Autologous Oblique Structural Peg Bone and Cancellous Chip Bone Grafting

BackgroudIn this study, we report satisfactory clinical and radiological outcomes after autologous oblique structural peg bone and cancellous chip bone grafting without metal augmentation, including the use of a metal wedge, block, or additional stem, for patients with ≥ 10-mm-deep uncontained medial proximal tibial bone defects in primary total knee replacement.MethodsThe study group included 40 patients with primary total knee replacement with ≥ 10-mm-deep uncontained tibial bone defects who underwent autologous oblique structural peg bone and cancellous chip bone grafting and were followed-up for at least 1 year. Tibial cutting was performed up to a depth of 10 mm from the articular surface of the lateral tibial condyle, after which the height and area of the remaining bone defect in the medial condyle were measured. The bone defect was treated by making a peg bone and chip bone using excised segments of the tibia and femur. In all cases, the standard tibial stem and full cemented fixation techniques were used without metal augmentation. Preoperative and final follow-up radiologic changes and clinical measures were compared, and prosthesis loosening and bone union were checked radiologically at final follow-up.ResultsThe mean depth of the bone defects was 10.9 mm, and the mean percentage of the area occupied by bone defects in the axial plane was 18.4%. The mean mechanical femorotibial angle was corrected from 19.5° varus preoperatively to 0.2° varus postoperatively (p < 0.002). There was no prosthesis loosening, and all cases showed bone union at the 1-year postoperative follow-up.ConclusionsEven in patients with uncontained tibial bone defects ≥ 10-mm deep in primary total knee replacement, if the defect occupies less than 30% of the cut surface, autologous oblique structural peg bone and cancellous chip bone grafting can be used to achieve satisfactory outcomes with a standard tibial stem and no metal augmentation.     

Analysis of medial tibial plateau fracture injury patterns using quantitative 3D measurements

BackgroundThe Wahlquist system classifies tibial medial plateau fractures into three types based on the sagittal fracture line location, with type C at highest risk of complications. However, the injury mechanism of tibial medial plateau fractures, especially tibial rotation movement, remains unclear. The purpose of the present study was to determine the injury patterns of medial tibial plateau fractures using 3D model simulation and quantitative 3D measurements.MethodsSeventy-eight consecutive AO/OTA type 41-B tibial plateau fractures were retrospectively analyzed using CT-based 3D models and quantitative 3D measurements. The knee posture at the moment of fracture occurrence was simulated, and various knee angles in the sagittal, coronal, and axial planes were measured to evaluate the mechanism of medial tibial plateau fracture. The mean valgus-varus, hyperextension-flexion, and internal-external rotation angles were determined, and the chi-square test was used for comparisons of categorical varus and valgus force data to determine the main force direction in Wahlquist type C fractures.ResultsAngle measurements in the coronal planes showed that 28 (35.9%) medial tibial plateau fractures resulted from a varus injury pattern, while 50 fractures (64.1%) resulted from a valgus pattern. Valgus force produced significantly more Wahlquist type C fractures (37 of 50 fractures) than varus force (2 of 28 fractures) (p < 0.05). There was no significant difference in the cases of patients with type C fractures between the tibial internal and external rotation injury patterns(P > 0.05).ConclusionsValgus force was the cause of 64.1% of the medial tibia plateau fractures in the present cohort. Furthermore, valgus force produced more Wahlquist type C fractures than varus force. The present findings will help orthopedists understand the injury mechanism of the Wahlquist classification system, and will facilitate the identification of the common features of medial tibial plateau fractures induced by specific injury patterns.     

Utility of Preoperative Distractive Stress Radiograph for Beginners to Extent of Medial Release in Total Knee Arthroplasty

Background

This study evaluated the preoperative distractive stress radiographs in order to quantify and predict the extent of medial release according to the degree of varus deformity in primary total knee arthroplasty.

Methods

We evaluated 120 varus, osteoarthritic knee joints (75 patients). The association of the angle on the distractive stress radiograph with extent of medial release was analyzed. The extent of medial release was classified into the following 4 groups according to the stage: release of the deep medial collateral ligament (group 1), release of the posterior oblique ligament and/or semimembranous tendon (group 2), release of the posterior capsule (group 3) and release of the superficial medial collateral ligament (group 4).

Results

The mean femorotibial angle on the preoperative distractive stress radiograph was valgus 2.4° (group 1), valgus 0.8° (group 2), varus 2.1° (group 3) and varus 2.7° (group 4). The extent of medial release increased with increasing degree of varus deformity seen on the preoperative distractive stress radiograph.

Conclusions

The preoperative distractive stress radiograph was useful for predicting the extent of medial release when performing primary total knee arthroplaty.