Prosthesis loosening is the leading cause of postoperative revision in unicompartmental knee arthroplasty (UKA). The deviation of medial and lateral translational installation of the prosthesis during surgery is a common clinical phenomenon and an important factor in increasing the risk of prosthesis loosening. This study established a UKA finite element model and a bone-prosthesis fixation interface micromotion prediction model. The predicted medial contact force and joint motion of the knee joint from a patient-specific lower extremity musculoskeletal multibody dynamics model of UKA were used as boundary conditions. The effects of 9 femoral component medial and lateral translational installation deviations on the Von Mises stress of the proximal tibia, the contact stress, and the micro-motion of the bone prosthesis fixation interface were quantitatively studied. It was found that compared with the neutral position (a/A of 0.492), the lateral translational deviation of the femoral component significantly increased the tibial Von Mises stress and the bone-prosthesis fixation interface contact stress. The maximum Von Mises stress and the maximum contact stress of the fixation interface increased by 14.08% and 143.15%, respectively, when a/A was 0.361. The medial translational deviation of the femoral component significantly increased the bone-prosthesis fixation interface micro-motion. The maximum value of micromotion under the conditions of femoral neutral and medial translation deviation was in the range of 20-50 μm, which is suitable for osseointegration. Therefore, based on considerations such as the micromotion range suitable for osseointegration reported in the literature, the risk of reducing prosthesis loosening, and factors that may induce pain, it is recommended that clinicians control the mounting position of the femoral component during surgery within the safe range of 0-4 mm medial translation deviation.
Humans ; Arthroplasty, Replacement, Knee/methods* ; Finite Element Analysis ; Biomechanical Phenomena ; Knee Prosthesis ; Tibia/surgery* ; Femur/surgery* ; Stress, Mechanical ; Prosthesis Failure ; Knee Joint/surgery* ; Prosthesis Design

Although metal blocks have been widely used for reconstructing uncontained tibial bone defects, the influence of their elastic modulus on the stability of tibial prosthesis fixation remains unclear. Based on this, a finite element model incorporating constrained condylar knee (CCK) prosthesis, tibia, and metal block was established. Considering the influence of the post-restraint structure of the prosthesis, the effects of variations in the elastic modulus of the block on the von Mises stress distribution in the tibia and the block, as well as on the micromotion at the bone-prosthesis fixation interface, were investigated. Results demonstrated that collision between the insert post and femoral prosthesis during tibial internal rotation increased tibial von Mises stress, significantly influencing the prediction of block elastic modulus variation. A decrease in the elastic modulus of the metal block resulted in increased von Mises stress in the proximal tibia, significantly reduced von Mises stress in the distal tibia, decreased von Mises stress of the block, and increased micromotion at the bone-prosthesis fixation interface. When the elastic modulus of the metal block fell below that of bone cement, inadequate block support substantially increased the risk of stress shielding in the distal tibia and fixation interface loosening. Therefore, this study recommends that biomechanical investigations of CCK prostheses must consider the post-constraint effect, and the elastic modulus of metal blocks for bone reconstruction should not be lower than 3 600 MPa.
Knee Prosthesis ; Humans ; Finite Element Analysis ; Tibia/surgery* ; Elastic Modulus ; Arthroplasty, Replacement, Knee/methods* ; Stress, Mechanical ; Metals ; Prosthesis Design ; Knee Joint/surgery* ; Biomechanical Phenomena

OBJECTIVE: To investigate the effectiveness of digital three-dimensional (3D) printing osteotomy guide plate assisted total knee arthroplasty (TKA) in treatment of knee osteoarthritis (KOA) patients with femoral internal implants. METHODS: The clinical data of 55 KOA patients who met the selection criteria between July 2021 and October 2023 were retrospectively analyzed. Among them, 26 cases combined with femoral implants were treated with digital 3D printing osteotomy guide plate assisted TKA (guide plate group), and 29 cases were treated with conventional TKA (control group). There was no significant difference in gender, age, body mass index, side, Kellgren-Lawrence classification, preoperative visual analogue scale (VAS) score, Hospital for Special Surgery (HSS) knee score, knee range of motion, and other baseline data between the two groups ( P>0.05). The operation time, intraoperative blood loss, incision length, postoperative first ambulation time, surgical complications; VAS score, knee HSS score, knee range of motion before operation, at 1 week and 3 months after operation, and at last follow-up; distal femoral lateral angle, proximal tibial medial angle, hip-knee-ankle angle and other imaging indicators at last follow-up were recorded and compared between the two groups. RESULTS: The operation time, incision length, intraoperative blood loss, and postoperative first ambulation time in the guide plate group were significantly lower than those in the control group ( P<0.05). In the control group, there were 1 case of incision rupture and bleeding and 1 case of lower limb intermuscular venous thrombosis, which was cured after symptomatic treatment. There was no complication such as neurovascular injury, incision infection, or knee prosthesis loosening in both groups. Patients in both groups were followed up 12-26 months, with an average of 16.25 months. The VAS score, HSS score, and knee range of motion improved at each time point after operation in both groups, and further improved with time after operation, the differences were significant ( P<0.05). The above indicators in the guide plate group were significantly better than those in the control group at 1 week and 3 months after operation ( P<0.05), and there was no significant difference between the two groups at last follow-up ( P>0.05). At last follow-up, the distal femoral lateral angle, the proximal tibial medial angle, and the hip-knee-ankle angle in the guide plate group were significantly better than those in the control group ( P<0.05). CONCLUSION The application of digital 3D printing osteotomy guide plate assisted TKA in the treatment of KOA patients with femoral implants can simplify the surgical procedures, overcome limitations of conventional osteotomy guides, reduce surgical trauma, achieve individualized and precise osteotomy, and effectively restore lower limb alignment and knee joint function.
Humans ; Arthroplasty, Replacement, Knee/instrumentation* ; Osteoarthritis, Knee/surgery* ; Osteotomy/instrumentation* ; Male ; Retrospective Studies ; Female ; Printing, Three-Dimensional ; Femur/surgery* ; Middle Aged ; Bone Plates ; Range of Motion, Articular ; Aged ; Treatment Outcome ; Surgery, Computer-Assisted/methods* ; Knee Prosthesis ; Knee Joint/surgery* ; Operative Time

OBJECTIVE: To investigate the effect of femoral condyle sliding osteotomy (FCSO) on the flexion gap and external rotation of the prosthesis in balancing coronal instability during initial total knee arthroplasty (TKA). METHODS: Between November 2021 and October 2024, FCSO technique was applied to balance the coronal medial and lateral spaces during initial TKA in 3 patients, including medial condyle sliding osteotomy (MCSO) and lateral condyle sliding osteotomy (LCSO). There were 1 male and 2 females with the age of 81, 68, and 68 years old. The affected knee has varus or valgus deformity, with tibia-femoral angles of 169.7°, 203.3°, and 162.2°, respectively. The hip-knee-ankle angle (HKA), range of motion (ROM), knee society scoring system (KSS), and pain visual analogue scale (VAS) score were used to evaluate joint function and pain relief. Based on model bone, the thickness and bone bed area of the medial and lateral femoral condyle osteotomy blocks in FCSO were measured. During TKA in 12 patients, the range of osteotomy block movement was evaluated. By simplifying the upward and forward movement of the osteotomy block into a geometric model, the impact of movement on the flexion gap and external rotation of the prosthesis was calculated. RESULTS: After application of FCSO during TKA, the limb alignment and medial and lateral balance at extension and flexion positions were restored in 3 patients. Three patients were followed up 23, 11, and 3 months, respectively. Postoperative HKA, pain VAS score, KSS score, and ROM all showed significant improvement compared to preoperative levels. The maximum thickness of osteotomy blocks by MCSO and LCSO was 17 and 12 mm, respectively. The simple upward movement of the osteotomy block mainly affected the extension gap, and had little effect on the flexion gap and external rotation of the prosthesis. Moving the osteotomy block forward at the same time had a significant impact on the flexion gap and external rotation of the prosthesis, especially on LCSO. Mild forward movement leaded to a decrease in external rotation of more than 3°, which had a serious impact on the patellar trajectory. CONCLUSION FCSO can effectively solve the problem of imbalance between the medial and lateral spaces during initial TKA, avoiding knee joint instability caused by excessive loosening and limiting the use of constrained condylar prosthesis. The distance for the downward movement of the osteotomy block in MCSO and LCSO was 3-5 mm and 6-8 mm, respectively, with 10-15 mm of space for forward movement and almost no space for backward movement. For MCSO, the upward and forward movement of the osteotomy block will increase the external rotation of the prosthesis, which is beneficial for improving the patellar trajectory and suitable for valgus knee. LCSO is suitable for varus knee, and the osteotomy block only slides vertically up and down without moving forward and backward.
Humans ; Osteotomy/methods* ; Male ; Female ; Arthroplasty, Replacement, Knee/methods* ; Aged ; Range of Motion, Articular ; Femur/surgery* ; Knee Joint/physiopathology* ; Aged, 80 and over ; Knee Prosthesis ; Treatment Outcome ; Osteoarthritis, Knee/surgery*

OBJECTIVE: To explore the effectiveness of artificial hemi-knee prosthesis reconstruction for bone defects after resection of pediatric osteosarcoma. METHODS: A retrospective analysis was conducted on the clinical data of 18 children with osteosarcoma who met the selection criteria and were treated between January 2016 and December 2019. There were 11 males and 7 females, aged 6-10 years (mean, 8.9 years). Osteosarcoma located in the distal femur in 11 cases and the proximal tibia in 7 cases. Among them, 12 cases were conventional osteosarcoma and 6 cases were small cell osteosarcoma, with a disease duration of 1-9 months (mean, 3.1 months). All patients received 2 cycles of preoperative chemotherapy with doxorubicin, cisplatin, and ifosfamide. After en bloc tumor segment resection, bone defects were reconstructed using custom-made artificial hemi-knee prostheses. Rehabilitation training was initiated at 8 weeks postoperatively under the protection of a knee immobilizer brace, combined with 4 cycles of adjuvant chemotherapy. During follow-up, lower limb growth length and limb shortening (compared with the healthy side) were measured, and limb function was evaluated using the Musculoskeletal Tumor Society-93 (MSTS-93) scoring system. RESULTS: All surgeries were successfully completed, with an operation time of 2.0-3.1 hours (mean, 2.4 hours) and intraoperative blood loss of 180-320 mL (mean, 230.0 mL). Incisional edge necrosis occurred in 1 case at 10 days postoperatively, while the incisions of the remaining 17 patients healed by first intention. One case developed periprosthetic infection caused by Staphylococcus aureus at 1 week postoperatively, which was cured after symptomatic treatment. All 18 patients were followed up 60-96 months (mean, 74.2 months). No local tumor recurrence was observed during follow-up. Imaging examinations showed prosthesis loosening in 2 cases, while the prosthesis of other patients were well-positioned. At last follow-up, the knee joint range of motion was 80°-120° (mean, 106.7°). The MSTS-93 score was 16-29 (mean, 24.7), with 12 cases rated as excellent, 5 good, and 1 fair. The patients' height increased by 12.8-20.0 cm (mean, 15.5 cm), the lower limb growth length was 6.0-13.0 cm (mean, 9.7 cm), and limb shortening was 1.8-4.6 cm (mean, 3.1 cm). There was no significant difference in MSTS-93 scores, lower limb growth length, or limb shortening between the distal femur group and the proximal tibia group ( P>0.05). CONCLUSION Artificial hemi-knee prosthesis reconstruction can preserve the adjacent normal epiphysis of the knee joint, maximize limb growth potential, and reduce adult limb length discrepancy, making it a suitable reconstruction option for children with knee osteosarcoma.
Humans ; Osteosarcoma/surgery* ; Male ; Child ; Female ; Knee Prosthesis ; Retrospective Studies ; Bone Neoplasms/surgery* ; Plastic Surgery Procedures/methods* ; Tibia/surgery* ; Femur/surgery* ; Arthroplasty, Replacement, Knee/methods* ; Treatment Outcome ; Chemotherapy, Adjuvant ; Femoral Neoplasms/surgery*

OBJECTIVE: To investigate the diagnostic efficacy of ^99mTc-MDP three-phase bone scintigraphy (TPBS) combined with C-reactive protein (CRP) for periprosthetic joint infection (PJI). METHODS: The clinical data of 198 patients who underwent revision surgery of artificial joint between January 2017 and January 2024 and received TPBS examination before surgery were retrospectively analyzed. There were 77 males and 121 females with an average age of 63.74 years ranging from 24 to 92 years. There were 90 cases of hip arthroplasty and 108 cases of knee arthroplasty. PJI was diagnosed according to the 2013 American Musculoskeletal Infection Society (MSIS) standard diagnostic criteria. The sensitivity, specificity, accuracy, negative predictive value (NPV), and positive predict value (PPV) were calculated. The receiver operating characteristic (ROC) curve was used to compare the diagnostic performance of the three methods, and the area under curve (AUC) was used to evaluate the diagnostic performance. RESULTS: According to the 2013 MSIS criteria, 116 cases were diagnosed as PJI, and the remaining 82 cases were aseptic loosening. The cases of PJI diagnosed by TPBS, CRP, and TPBS-CRP were 125, 109, and 137 respectively, and the cases of aseptic loosening were 73, 89, and 61 respectively. The sensitivity, accuracy, NPV, and PPV of TPBS-CRP combination in the diagnosis of PJI were higher than those of TPBS and CRP, but the specificity was lower than that of TPBS and CRP. ROC curve analysis further showed that the AUC value of TPBS-CRP combination was better than that of TPBS and CRP. The severity of bone defect and the duration of symptoms in patients with false positive TPBS diagnosis were worse than those in patients with true negative TPBS diagnosis (P<0.05), but there was no significant difference in the survival time of prosthesis between the two groups (P>0.05). Among the patients diagnosed with PJI by TPBS, CRP, and TPBS-CRP, 49, 35, and 54 patients had received antibiotic treatment 2 weeks before diagnosis, respectively. There was no significant difference in the diagnostic accuracy of TPBS and TPBS-CRP before diagnosis between patients treated with and without antibiotics and those not treated (P>0.05). The diagnostic accuracy of antibiotic therapy before CRP diagnosis was significantly lower than that of untreated patients (P<0.05). CONCLUSION TPBS and CRP have limited specificity in differentiating PJI from aseptic loosening. The TPBS-CRP combination diagnostic method can synergize the local bone metabolic characteristics and systemic inflammatory response to achieve higher diagnostic accuracy, but caution should be exercised in patients with severe bone defects and longer symptom duration.
Humans ; Prosthesis-Related Infections/blood* ; Middle Aged ; Male ; Female ; Aged ; C-Reactive Protein/metabolism* ; Retrospective Studies ; Adult ; Radionuclide Imaging/methods* ; Arthroplasty, Replacement, Knee/adverse effects* ; Aged, 80 and over ; Technetium Tc 99m Medronate ; Arthroplasty, Replacement, Hip/adverse effects* ; Sensitivity and Specificity ; Knee Prosthesis/adverse effects* ; ROC Curve ; Reoperation ; Radiopharmaceuticals ; Young Adult

OBJECTIVE: To investigate the clinical utility of novel of new hematological markers in the preoperative diagnosis of periprosthetic joint infection (PJI). METHODS: A retrospective analysis was conducted on a total of 149 patients who underwent revision of total hip arthroplasty (THA) or total knee arthroplasty (TKA) at a single center between January 2016 and June 2022, including 63 males and 86 females, aged from 47 to 93 years old with an average of (69.5±11.8) years old. Of them, 46 were diagnosed as PJI(PJI group), including 22 males and 24 females. The mean age was (71.3±12.5) years old. The body mass index (BMI) was (26.4±3.1) kg·m^-2. And 103 patients were diagnosed as aseptic prosthesis loosening (aseptic group), including 41 males and 62 females. The mean age was (68.7±11.4) years old. The BMI was (25.8±3.5) kg·m^-2. Preoperatively analyzed clinical parameters included C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), albumin, globulin, albumin-to-globulin ratio (AGR), plasma D-dimer, and plasma fibrinogen. The receiver operating characteristic curve (ROC), sensitivity, and specificity analysis were employed to compare the diagnostic value of each blood marker in preoperative PJI diagnosis. RESULTS: In the PJI group, the levels of CRP were 16.6 (7.6, 4.5) mg·L^-1, ESR was 17.0 (12.8, 35.5) mm·h^-1, plasma D-dimer was 1.0 (0.5, 3.1) μg·L^-1, and plasma fibrinogen was 4.2 (3.2, 3.1) mg·L^-1;all of which were higher compared to the aseptic group with CRP at 4.2 (2.6, 7.8) mg·L^-1, ESR at 12.0(8.0, 20.0 )mm·h^-l, D-dimer at 0.4(0.2, 0.7)μg·L^-1, and fibrinogen at 2.8(2.4, 3.3 ) g·L^-1(P<0.05). However, the albumin level of 35.3 (32.3, 37.5) g·L^-1 and the WBC ratio of 1.0(0.9, 1.1) in the PJI group were significantly lower compared to the aseptic group with levels of 39.8 (36.1, 41.8) g·L^-1 and 1.4 (1.3, 1.5), respectively (P<0.05). Only the area under the curve (AUC) of AGR and plasma fibrinogen were greater than 0.8. The optimal predictive cut-1off, AUC, sensitivity and specificity were 3.4 g·L-1, 0.820, 69.57% and 84.47% for plasma fibrinogen; 1.18, 0.813, 82.61% and 78.64% for AGR, respectively. CONCLUSION AGR and plasma fibrinogen are promising blood markers for improving the diagnosis of PJI.
Humans ; Female ; Fibrinogen/metabolism* ; Male ; Middle Aged ; Aged ; Prosthesis-Related Infections/blood* ; Retrospective Studies ; Biomarkers/blood* ; Aged, 80 and over ; Arthroplasty, Replacement, Knee/adverse effects* ; Arthroplasty, Replacement, Hip/adverse effects* ; Leukocyte Count

OBJECTIVE: To explore the role of antibiotic-eluting absorbable calcium sulfate in treating periprosthetic infection after one-stage revision of knee arthroplasty. METHODS: A retrospective analysis was performed on 36 patients(36 knees)who underwent phaseⅠrevision for periprosthesis infection after total knee arthroplasty from January 2018 to March 2022. All patients were underwent knee cavity puncture before operation and had positive results of aseptic body fluid culture, 21 patients received revision combined with antibiotic loaded calcium sulfate at stageⅠ(calcium sulfate group) during operation, and 15 patients underwent renovation at stageⅠ(revision group). There were 9 males and 12 females in calcium sulfate group, aged from 54 to 76 years old with an average of(67.6±6.2) years old. There were 15 patients in revision group, including 4 males and 11 females, aged from 60 to 75 years old with average of (69.6±4.1) years old. The levels of serum C-reactive protein (CRP), interleukin-6 (IL-6) at 7, 14, 30 and 90 days after operation were compared between two groups, and the rate of end-infection control at follow-up were compared. The systemic antibiotic application time, hospital stay and postoperative complications were observed between two groups. RESULTS: Calcium sulfate group were followed up for 12 to 29 months with an average of(18.9±4.2) months, and the infection control rate was 90.5%;while revision group were followed up 18 to 29 months with average of (21.6±3.7) months, and the infection control rate was 86.7% (13/15). There were no significant differences in follow-up time and infection control rate between two groups(P>0.05). Postoperative levels of CRP and IL-6 at 7, 14 and 30 days in calcium sulfate group were (32.79±11.48), (15.50±6.52), (9.36±3.32) mg·L^-1 and (17.31±6.15) pg·ml^-1, respectively;which were lower than those in revision group (40.65±11.32), (30.15±10.57), (18.97±5.86) mg·L^-1 and (25.54±6.73) pg·ml^-1, had statistical differences(P<0.05). There were no significant differences in IL-6 levels at 7 and 14 days after operation and CRP levels at 90 days after operation between two groups (P>0.05). The hospitalization time and systemic antibiotic application time in calcium sulfate group were (18.4±2.2) and (63.5±21.4) d, respectively;which were better than those in revision group (20.5±2.4) and (82.7±16.9) d, and had statistical differences(P<0.05). No significant wound complications and hypercalcemia were observed in calcium sulfate group. CONCLUSION Antibiotic eluted absorbable calcium sulfate could be used to treat periprosthetic knee infection, significantly reducing CRP levels in the early postoperative period, shortening hospital stay and systemic antibiotic application time, but it does not significantly improve the control rate of revision infection at stageⅠ.
Humans ; Male ; Female ; Aged ; Prosthesis-Related Infections/surgery* ; Middle Aged ; Calcium Sulfate/administration & dosage* ; Arthroplasty, Replacement, Knee/adverse effects* ; Retrospective Studies ; Anti-Bacterial Agents/therapeutic use* ; Interleukin-6/blood* ; C-Reactive Protein/metabolism* ; Reoperation ; Knee Prosthesis/adverse effects*

PURPOSE: End-stage knee osteoarthritis (OA) patients are the primary candidates for total knee arthroplasty (TKA). However, most morphological refinements of TKA prosthesis are based on anatomical data from the knees of healthy individuals. This study aimed to determine whether differences exist in key bony morphological characteristics of the distal femur and proximal tibia between osteoarthritic knees and healthy knees. METHODS: This was a retrospective cross-sectional observational study with a case-control design. Patients who were aged ≥ 50 years, had no history of trauma, fracture, or surgery in the studied knee, and had no obvious knee flexion contracture were included in this study by CT scans. Patients who met the American College of Rheumatology clinical criteria for knee OA were included in the study group. Kellgren-Lawrence grade III or IV knees were studied (for bilateral cases, the more severely affected knee was chosen). Patients who presented with unilateral knee pain or trauma were included in the control group, with CT scans from the opposite (asymptomatic) knee used for analyzing. The studied knee had a Kellgren-Lawrence grade of 0 or I and showed no abnormalities upon physical examination. Archived knee CT scans from 160 patients were divided into 2 groups: the study group (80 moderate-to-severe OA knees) and the control group (80 healthy knees). After 3-dimensional reconstruction and virtual cutting using a CT workstation, 13 morphological parameters of the distal femur and proximal tibia were compared between the 2 groups using independent-samples t-tests. RESULTS: No significant group differences in the femoral anteroposterior dimension (p = 0.797), height of the lateral femoral condyle (p = 0.268), posterior condylar angle (p = 0.240), tibial anteroposterior dimension (p = 0.536), or tibial lateral anteroposterior dimension (p = 0.702) were observed. However, the femoral mediolateral dimension (p = 0.002), distal femoral aspect ratio (femoral mediolateral dimension/femoral anteroposterior dimension) (p < 0.001), height of the femoral trochlear groove (p < 0.001), height of the medial femoral condyle (p < 0.001), tibial mediolateral dimension (p = 0.001), proximal tibial aspect ratio (tibial mediolateral dimension/tibial anteroposterior dimension) (p = 0.004), tibial medial anteroposterior dimension (p = 0.005), and tibial asymmetry ratio (tibial medial anteroposterior dimension/tibial lateral anteroposterior dimension) (p = 0.006) were all significantly greater in the study group. CONCLUSION Knees with moderate-to-severe OA are significantly wider than healthy knees, and OA is a risk factor for increased tibial platform asymmetry. When refining the morphological parameters of TKA prostheses, the specific bony morphological characteristics of OA knees should be taken into account to reduce the potential risk of femoral or tibial component underhang and facilitate optimal balance between tibial component fit and rotational alignment.
Humans ; Osteoarthritis, Knee/pathology* ; Male ; Female ; Cross-Sectional Studies ; Retrospective Studies ; Arthroplasty, Replacement, Knee ; Middle Aged ; Aged ; Case-Control Studies ; Prosthesis Design ; Knee Prosthesis ; Femur/anatomy & histology* ; Tibia/anatomy & histology* ; Tomography, X-Ray Computed ; Knee Joint/diagnostic imaging*

Compared with total knee arthroplasty, unicondylar knee replacement has the advantage of preserving the knee tissue structure and motor function to the greatest extent. Pre-clinical in-vitro test is an important tool to evaluate the safety and effectiveness of unicondylar knee prostheses, and it is also a key focus of the product registration process. Through collection, comparison, and analysis of current regulations, technical standards, guidelines, and related research literature, this paper expounds on the relevant research methods for the pre-clinical in-vitrotesting of unicondylar knee prostheses. At the same time, in conjunction with current evaluation requirements and experience, the study discusses the focus of pre-clinical performance research for unicondylar knee prostheses during the registration process to clarify the performance evaluation requirements of this product category. This aims to provide a reference for the pre-clinical performance research of unicondylar knee prostheses and to standardize industry testing standards.
Knee Prosthesis ; Arthroplasty, Replacement, Knee ; Humans ; Prosthesis Design ; Materials Testing