Objective To investigate the rotational mismatch of total kneereplacement with medial 1/3 of tibial tuberosity as bony landmark in osteoarthritic patients with varus or valgus deformity. Methods Axial images on computed tomography of 62 knees (including 55 varus deformities and 7 valgus deformities) in 32 Chinese osteoarthritic patients who had total knee arthroplasty were analyzed, compared with that of 10 healthy knees. On images of the distal femur, the angle between the lines of surgical epicondylar axis(SEA) and posterior condylar axis was measured as posterior condylar angle (PCA), and on images of the proximal tibia, a baseline for the anteriorposterior axis of each component was drawn based on the SEA for the femur and the medial 1/3 of the tibial tuberosity for the tibia. The angle between these lines (Angle α) was defined as therotational mismatch between the components when they were aligned to the anatomic landmarks of each bone. Results The sulcus of medial epicondyle of femur could be identified on CT images of over 80% osteoarthritic knees; the median value of PCA was +2.36°, with an individual variation of 0° to +7.5°. Angle α was +6.45±3.68°(range, 0° to +11.8°) in 10 healthy knees, which increased significantly to +10.85±10.47°(range, 0° to +28.1°)in 55 varus knees (P＜0.05), which also increased significantly to +11.6±7.3°(range, -6.5° to +26.8°) in 7 valgus knees (P＜ 0.05). Conclusion With the medial 1/3 of the tibial tuberosity as the rotational landmark for the tibial component, there was a tendency to align the tibial component in external rotational position relative to the femoral component in knees with normal alignment, the rotational mismatch increased in Chinese osteoarthritic knees with varus and valgus deformity.
ObjectiveTo investigate the improvement of femoral rotation alignment in total knee arthroplasty (TKA) by robotic-arm assisted positioning and osteotomy and its short-term effectiveness.MethodsBetween June 2020 and November 2020, 60 patients (60 knees) with advanced osteoarthritis of the knee, who met the selection criteria, were selected as the study subjects. Patients were randomly divided into two groups according to the random number table method, with 30 patients in each group. Patients were treated with robotic-arm assisted TKA (RATKA) in trial group, and with conventional TKA in control group. There was no significant difference in gender, age, side and course of osteoarthritis, body mass index, and the preoperative hip-knee-ankle angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), posterior condylar angle (PCA), knee society score-knee (KSS-K) and KSS-function (KSS-F) scores between the two groups (P>0.05). The clinical (KSS-K, KSS-F scores) and imaging (HKA, LDFA, MPTA, PCA) evaluation indexes of the knee joints were compared between the two groups at 3 months after operation.ResultsAll patients were successfully operated. The incisions in the two groups healed by first intention, with no complications related to the operation. Patients in the two groups were followed up 3-6 months, with an average of 3.9 months. KSS-K and KSS-F scores of the two groups at 3 months after operation were significantly higher than those before operation (P<0.05), but there was no significant difference between the two groups (P>0.05). X-ray re-examination showed that the prosthesis was in good position, and no prosthesis loosening or sinking occurred. HKA, MPTA, and PCA significantly improved in both groups at 3 months after operation (P<0.05) except LDFA. There was no significant difference in HKA, LDFA, and MPTA between the two groups (P>0.05). PCA in trial group was significantly smaller than that in control group (t=2.635, P=0.010).ConclusionRATKA can not only correct knee deformity, relieve pain, improve the quality of life, but also achieve the goal of restoring accurate femoral rotation alignment. There was no adverse event after short-term follow-up and the effectiveness was satisfactory.
Objective To explore the prediction of postoperative coronal lower limb alignment by the tibia fibular angle (TFA) and femoral fibular angle (FFA) after osteotomy in medial open-wedge high tibial osteotomy (MOWHTO). Methods A clinical data of 20 patients with medial compartment osteoarthritis, who were treated with MOWHTO between September 2019 and September 2020, was retrospectively analyzed. Among them, there were 9 males and 11 females; the age ranged from 46 to 69 years, with an average of 56.0 years. The body mass index (BMI) was 21.3- 35.7 kg/m2, with an average of 26.7 kg/m2. Osteoarthritis involved 11 cases of left knee and 9 cases of right knee; the disease duration was 2-6 years, with an average of 3.8 years. According to the Kellgren-Lawrence classification, there were 7 cases of grade Ⅰ, 9 cases of grade Ⅱ, and 4 cases of grade Ⅲ. The angle and height for open-wedge was planned preoperatively by osteotomy master software, and the TFA and FFA were measured by software after simulated osteotomy. The intraoperative angle for open-wedge was adjusted according to TFA and FFA after simulated osteotomy.The lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), mechanical femorotibial angle (mFTA), weight-bearing line (WBL) ratio, TFA, and FFA were measured before operation and at 2 days after operation. The difference (X) between the intraoperative measurement value and the preoperative plan value of TFA/FFA, and the difference (Y) between the postoperative WBL ratio and the target alignment (62.5%) were calculated, and the correlation between the two indicators was analyzed by Pearson’s test. According to the median BMI of patients (25.81 kg/m2), the patients were allocated into high BMI group (>25.81 kg/m2, n=10) and low BMI group (≤25.81 kg/m2, n=10), and the influencing factors of WBL ratio was analyzed by linear regression. Results There was no significant difference between pre- and post-operation in LDFA and JLCA (P>0.05); while there were significant differences between pre- and post-operation in MPTA, mFTA, and WBL ratio (P<0.05). The TFA was (89.5±4.0)° during operation and (87.7±4.7)° after operation, showing significant difference (t=2.991, P=0.008). There was a positive correlation between the difference (X) between the intraoperative measurement value and the preoperative plan value of TFA and the difference (Y) between the postoperative WBL ratio and the target alignment (r=0.595, P=0.006). The FFA was (86.9±4.3)° during operation and (85.7±4.4)° after operation, showing significant difference (t=1.760, P=0.094). There was a positive correlation between the difference (X) between the intraoperative measurement value and the preoperative plan value of FFA and the difference (Y) between the postoperative WBL ratio and the target alignment (r=0.536, P=0.015). After BMI stratification, X was an influential factor of Y in the low BMI group (P<0.05), but X was not an influential factor of Y in the high BMI group (P>0.05). Conclusion Intraoperative FFA and TFA can predict coronal limb alignment after MOWHTO. FFA and TFA can predict more preciselyfor patients with BMI≤25.81 kg/m2.
ObjectiveTo investigate the short-term effectiveness of novel computer navigation system (Knee 3 software; Brainlab, Germany) assisted total knee arthroplasty (TKA).MethodsBetween July 2020 and December 2020, 19 patients underwent unilateral TKA assisted with Knee 3 software. There were 4 males and 15 females. The mean age was 66.3 years (range, 52-79 years). Eighteen patients were diagnosed with osteoarthritis and 1 patient with rheumatoid arthritis. Sixteen patients had varus knees and 3 patients had valgus knees. Preoperative Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain, stiffness, function, and total scores were 12.4±3.4, 2 (1, 4), 22 (18, 29), and 37 (29, 43), respectively. Intraoperatively, the medial and lateral gaps in knee extension and in 90° of knee flexion were recorded. The operation time, intraoperative blood loss, blood transfusion, and complications were recorded. The hip-knee-ankle angle (HKA), lateral distal femoral angle, and medial proximal tibial angle were measured to evaluate lower limb alignment and prostheses’s alignment using X-ray films at 6 weeks after operation. Patient’s satisfaction rate and WOMAC pain, stiffness, function, and total scores were investigated.ResultsEighteen patients (94.7%) had medial- lateral gap balancing in knee extension, 18 patients (94.7%) had medial-lateral gap balancing in 90° of knee flexion, 19 patients (100%) had medial gap balancing between knee extension and 90° of knee flexion, and 18 patients (94.7%) had lateral gap balancing between knee extension and 90° of knee flexion. The mean operation time was 126 minutes (range, 100-200 minutes). The mean intraoperative blood loss was 205 mL (range, 100-400 mL). Patients were followed up 4-8 months, with an average of 6.2 months. Postoperative complications included 1 deep vein thrombosis of lower extremities and 1 cerebral infarction. X-ray films showed that the mean HKA, lateral distal femoral angle, and medial proximal tibial angle were 179.8° (range, 178°-182°), 83.5° (range, 80°-87°), and 89.5° (range, 87°-93°), respectively. At last follow-up, WOMAC pain, stiffness, function, and total scores were 3.6±1.9, 0 (0, 2), 4 (2, 6), and 9 (5, 10), respectively, which improved when compared with preoperative scores (P<0.05). Twelve patients were very satisfied with the operation results and 7 patients were satisfied with the operation results. The overall satisfaction rate was 100%.ConclusionKnee 3 software can help to obtain good gap balancing and optimal lower limb alignment, with high patient’s satisfaction and good short-term effecectiveness.
Objective To review the progress of total ankle arthroplasty (TAA) in treatment of end-stage ankle osteoarthritis (AOA). Methods The domestic and foreign literatures about TAA in recent years were reviewed. The current status and progress of TAA were summarized from the results of traditional and computer-assisted TAA clinical outcomes. Results End-stage AOA often leads to severe pain and dysfunction, and arthrodesis is still the main selective treatment option. In recent years, with the advancement of surgical techniques and prosthesis design, TAA which can remain joint mobility has increased gradually, and the surgical results also have significant progress. Accurate prosthesis implant and mechanical alignment restoration are critical factors for TAA, and surgery-related malalignment is correlative to the prosthesis failure. Computer assisted patient-specific guide can simplify the TAA procedures and obtain the accuracy of tibia and talus osteotomy. Conclusion The clinical efficiency of preoperative CT based patient-specific guide technology for TAA needs further clinical follow-up. Meanwhile, it is necessary to further develop intraoperative navigation and robotic surgery system suitable for TAA.
ObjectiveTo summarize the clinical application and research status of open wedge high tibial osteotomy (OWHTO).MethodsRelevant literature at home and abroad was reviewed, and the clinical application, effectiveness and complications, technical comparison, and surgical skills of OWHTO were summarized and analyzed.ResultsOWHTO is an effective treatment for mild to moderate medial compartment osteoarthritis due to knee varus. This method can delay the injury process of medial compartment of the knee, delay the time of total knee arthroplasty, and even avoid joint replacement surgery by adjusting the axial alignment of the lower extremity to the non-pathological lateral compartment through osteotomy and orthopedic. OWHTO has the advantages of small incision, dynamic adjustment of the axial alignment of the lower extremity, accurate correction of malformation, and rapid postoperative recovery.ConclusionWith the development of surgical instruments and techniques, OWHTO once again enter the sight of orthopedic surgeons. This technique can solve the pain symptoms of arthritis, correct the tibial varus deformity and reconstruct the axial alignment of the lower extremity, and satisfactory clinical results has been obtained.
Objective To investigate the effect of Navio robot-assisted unicompartmental knee arthroplasty (UKA) on the biomechanics of knee joint during sitting-up movement, and to determine whether UKA can maintain the biomechanical characteristics of knee joint. Methods The clinical data of 8 patients with medial compartment osteoarthritis treated with medial fixed platform of Navio robot-assisted UKA between January 2018 and January 2019 and had the complete follow-up data were retrospectively analyzed. There were 4 males and 4 females; the age ranged from 58 to 67 years, with an average of 62.3 years. The disease duration was 6-18 months, with an average of 13 months. The varus deformity ranged from 4° to 6°, with an average of 5°; the knee flexion range of motion was 0°-130°, with an average of 110°. All patients had no extension limitation. The imaging data of bilateral knees during sitting-up movement were collected by biplane C-arm X-ray machine at 3 weeks before operation and 7 months after operation. The three-dimensional models of femur and tibia were established by dual-energy CT scanning, and the three-dimensional models of femur and tibia were matched and synchronized with the femur and tibia in X-ray film by automatic matching tracer software. The biomechanical parameters of femur and tibia were measured, including internal rotation/external rotation, varus/valgus, forward/backward displacement of medial and lateral tibia contact center, and lateral compartment joint space. Results Eight patients were followed up 5-7 months, with an average of 6.4 months. In the comparison of the affected side before and after operation, except for the difference of varus/valgus which was significant (t=4.959, P=0.002), the differences in other indicators was not significant (P>0.05). There were significant differences in varus/valgus and internal rotation/external rotation between healthy and affected sides at 3 weeks before operation (P<0.05), and the differences in other indicators was not significant (P>0.05). At 7 months after operation, the difference in the forward and backward displacement of medial tibia contact center was significant (t=3.798, P=0.007), and the differences in other indicators was not significant (P>0.05). Conclusion UKA can effectively correct the varus and valgus of the knee joint, and restore the rotational biomechanical characteristics of the affected knee joint. It does not affect the establishment of the lateral compartment joint space, but the medial and lateral tibia contact center still changes.
ObjectiveTo investigate the effect of three-dimensional (3D) printing guide plate on improving femoral rotational alignment and patellar tracking in total knee arthroplasty (TKA).MethodsBetween January 2018 and October 2018, 60 patients (60 knees) with advanced knee osteoarthritis who received TKA and met the selection criteria were selected as the study subjects. Patients were randomly divided into two groups according to the random number table method, with 30 patients in each group. The TKA was done with the help of 3D printing guide plate in the guide group and following traditional procedure in the control group. There was no significant difference in gender, age, disease duration, side, and preoperative hip-knee-ankle angle (HKA), posterior condylar angle (PCA), patella transverse axis-femoral transepicondylar axis angle (PFA), Hospital for Special Surgery (HSS) score, and American Knee Society (AKS) score (P>0.05).ResultsAll incisions healed by first intention and no complications related to the operation occurred. All patients were followed up 10-12 months, with an average of 11 months. HSS score and AKS score of the two groups at 6 months after operation were significantly higher than those before operation (P<0.05), but there was no significant difference between the two groups (P>0.05). Postoperative X-ray films showed that the prosthesis was in good position, and no prosthesis loosening or sinking occurred during follow-up. HKA, PCA, and PFA significantly improved in the two groups at 10 months after operation compared with those before operation (P<0.05). There was no significant difference in HKA at 10 months between the two groups (t=1.031, P=0.307). PCA and PFA in the guide group were smaller than those in the control group (P<0.05).ConclusionApplication of 3D printing guide plate in TKA can not only correct the deformity of the knee joint and alleviate the pain symptoms, but also achieve the goal of the accurate femoral rotation alignment and good patellar tracking.
Lower limb alignment and soft tissue balance are important factors affecting patient satisfaction, clinical functional outcome, and prosthetic long-term survival rate after total knee arthroplasty (TKA). Robot-assisted TKA (rTKA) has the advantages of achieving precise osteotomy and soft tissue balance. However, rTKA under the guidance of classic mechanical alignment principles does not significantly improve the functional outcome after operation. The new TKA alignment principles, such as kinematic alignment (KA) and functional alignment (FA), can better consider the patient’s own knee joint morphology and kinematic characteristics, which may help improve the clinical results of TKA. With the help of more objective and accurate soft tissue balance assessment tool such as pressure sensors, KA and FA have been proven to better achieve soft tissue balance. rTKA can achieve non-neutral alignment goals such as KA or FA more accurately and reproducibly. The use of these lower limb alignment and soft tissue balancing strategies will be expected to further increase the patients’ satisfaction rate after rTKA.
Objective To establish a finite element model of the knee joint based on coronal plane alignment of the knee (CPAK) typing method, and analyze the biomechanical characteristics of different types of knee joints.Methods The finite element models of the knee joint were established based on CT scan data of 6 healthy volunteers. There were 5 males and 1 female with an average age of 24.2 years (range, 23-25 years). There were 3 left knees and 3 right knees. According to the CPAK typing method, the knees were rated as types Ⅰ to Ⅵ. Under the same material properties, boundary conditions, and axial loading, biomechanical simulations were performed on the finite element model of the knee joint. Based on the Von Mises stress nephogram and displacement nephogram, the peak stresses of the meniscus, femoral cartilage, and tibial cartilage, and the displacement of the meniscus were compared among different types of knee joints. Results The constructed finite element model of the knee joint was verified to be effective, and the stress and displacement results were consistent with previous literature. Under the axial load of 1 000 N, the stress nephogram showed that the stress distribution of the medial and lateral meniscus and tibial cartilage of CPAK type Ⅲ knee joint was the most uneven. The peak stresses of the lateral meniscus and tibial cartilage were 9.969 6 MPa and 2.602 7 MPa, which were 173% and 165% of the medial side, respectively. The difference of peak stress between the medial and lateral femoral cartilage was the largest in type Ⅳ knee joint, and the medial was 221% of the lateral. The displacement nephogram showed that the displacement of the medial meniscus was greater than that of the lateral meniscus except for types Ⅲ and Ⅵ knee joints. The difference between medial and lateral meniscus displacement of type Ⅲ knee joint was the largest, the lateral was 170% of the medial. Conclusion In the same type of joint line obliquity (JLO), the medial and lateral stress distribution of the knee was more uniform in varus and neutral positions than in valgus position. At the same time, the distal vertex of JLO subgroup can help to reduce the uneven medial and lateral stress distribution of varus knee, but increase the uneven distribution of valgus knee.