Comparison of finite helical axes of normal and anatomically designed prosthetic knees.

BACKGROUND: Describing three-dimensional joint motion using the finite helical axis has an advantage in understanding unknown coupling motion in prosthetic knee joints. We aimed to examine the differences in the orientations of finite helical axis of normal and anatomically designed cruciate-retaining and posterior-stabilized prosthetic knees after total knee arthroplasty. METHODS: Ten normal, 40 cruciate-retaining prosthetic knees of 33 patients and 19 posterior-stabilized prosthetic knees of 14 patients enabling to flex > 120° were analyzed during a squatting motion with deep knee bending. The motion was recorded by a fluoroscopic imaging system, and the pose of the bone and prostheses were determined by an image registration technique. The finite helical axes were calculated using 30° window. FINDINGS: The finite helical axis in the early flexion phase of the normal knees had a greater inferior inclination (mean - 19.0° (SD 7.2°)) than those of the cruciate-retaining (mean - 1.7 (SD 5.0°)) and posterior-stabilized (mean - 2.9° (SD 5.5°)) prosthetic knees (p < 0.001), and became almost horizontal and constant in the mid to deep flexion phases. In contrast, the cruciate-retaining and posterior-stabilized prosthetic knees demonstrated slightly inclined and almost constant vertical angles throughout the all phases. INTERPRETATION: These results demonstrate that, in the normal knee, a clear coupling motion occurs during the early flexion phase. For the cruciate-retaining and posterior-stabilized prosthetic knees, an unclear coupling motion exists during all phases. These results suggest that the physiological motion is not possible to reproduce using shape-guided motion only even in an anatomically designed prosthetic knee.

Influence of Posterior Tibial Slope on Kinematics After Cruciate-Retaining Total Knee Arthroplasty.

BACKGROUND: The purpose of this study was to investigate the influence of posterior tibial slope (PTS) on knee kinematics after cruciate-retaining total knee arthroplasty (CR-TKA). These influences were evaluated using a prosthesis designed with high geometric conformity to the medial articular surface under the weight-bearing condition of deep knee bending. METHODS: We evaluated 71 knees (52 patients) after CR-TKA using 2- to 3-dimensional registration techniques. All patients were categorized into 2 groups: group A (PTS ≤ 7°) and group B (PTS ≥ 8°). We compared in vivo knee kinematics during deep knee bending under weight-bearing conditions between the 2 groups. The anteroposterior position of the nearest points, flexion angles, and external rotation angles of the femoral components relative to the tibial components were evaluated. Additionally, the knee flexion angles of the femur relative to the tibia obtained from the installation angles of the components were evaluated. RESULTS: PTS did not affect the external rotation angles and anteroposterior position. The postoperative maximum flexion angle and range of motion between the femur and tibia in group B were significantly greater than those in group A. CONCLUSION: PTS of 8° or more in CR-TKA using prosthetics designed with high geometric conformity to the medial articular surface did not affect the anteroposterior position and external rotation, but increased the postoperative maximum flexion angle and range of motion.

Graft quality and clinical outcomes of intraoperative bone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction.

BACKGROUND/OBJECTIVE: In anatomic double-bundle anterior cruciate ligament reconstruction, it is crucial to create two separate bone tunnels within the footprints of the anterior cruciate ligament at the femur and tibia. This can occasionally be difficult to accomplish and the adverse effects of bone tunnel communication are unclear. The purpose of this study was to examine the effects of intraoperative bone tunnel communication on graft quality and clinical outcome. METHODS: Fifty-two patients (52 knees) who underwent anatomic double-bundle anterior cruciate ligament reconstruction with hamstring tendons were included. The mean age of the patients was 30.7 years. Clinical assessments were performed 1 year after surgery. Bone tunnel communication was evaluated using computed tomography 10 days after surgery. Graft quality was evaluated using magnetic resonance imaging 6 months after surgery and the signal/noise quotient was calculated using the region of interest technique. RESULTS: Bone tunnel communication was observed in the femur of one knee (1.9%) and the tibias of 10 knees (30.8%). The knees with tibial bone communication were classified into Group C (N = 16), and the knees without tibial bone tunnel communication were classified into Group N (N = 36). No significant differences were observed between Groups C and N in terms of clinical outcome. The signal/noise quotient of the distal portion of the posterolateral graft in Group C was significantly higher than that of Group N. CONCLUSION: Bone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction did not affect clinical outcome, but it did affect posterolateral graft quality. LEVEL OF EVIDENCE: Level 4, case series, therapeutic studies.

Drug free remission after steroid-dependent disappearance of lymphoproliferative disorder in rheumatoid arthritis patient treated with TNF-alpha blockade: case study.

INTRODUCTION: TNF-α inhibitors plus MTX appear to have benefit in the longer-term reduction of RA. Boolean long-term remission under drug-free conditions is rare. The therapeutic mechanism and the factor of predicting response have not been clarified yet. CASE DESCRIPTION: A 24-year-old female rheumatoid arthritis (RA) patient, who once attained complete remission (CR) with the combination therapy with tumor necrosis factor alpha (TNF-alpha) inhibitor adalimumab (ADA) and methotrexate (MTX), showed the occurrence of Epstain- Barr virus (EBV)-associated lymphoproliferative disorder (LPD). Pulse treatment with methylprednisolone after the termination of anti TNF-α therapy resulted in the remission of EBV-associated LPD. The administration of prednisolone (PSL) was tapered off after the improvement of clinical symptoms and laboratory data. The patients achieved drug-free 12 months after urgent hospitalization and delivered healthy baby 2 years after hospital discharge. She has been complete drug-free Boolean remission for 5 years. DISCUSSION AND EVALUATION: The purpose of this brief case is report that we experienced the remission of LPD after CR with combined therapy with ADA and MTX. We believe this case report will be one of the paths for unveiling the pathogenesis and improving the treatment for RA. CONCLUSIONS: We believe this case report will be one of the paths for unveiling the pathogenesis and improving the treatment for RA.

Sagittal view of the tibial attachment of the anterior cruciate ligament on magnetic resonance imaging and the relationship between anterior cruciate ligament size and the physical characteristics of patients.

BACKGROUND: It is necessary to create bone tunnels within the native footprint during anatomic anterior cruciate ligament (ACL) reconstruction. Predicting the size of the ACL preoperatively may be useful in order to determine the diameter of the bone tunnels preoperatively or during surgery. The tibial insertion site of the ACL includes a depressed area, the ACL fovea, which is generally observed in the sagittal view on magnetic resonance imaging (MRI). The purposes of this study were to measure the anteroposterior diameter of the ACL fovea in the sagittal view on MRI and to investigate its associations with the physical characteristics of patients. METHODS: One hundred patients (100 knees; 50 males and 50 females; mean age, 33 years) were included in this study. The anteroposterior diameter of the ACL fovea was measured in the sagittal view on MRI. The relationships between the diameter of the ACL fovea and physical characteristics including height, weight, and body mass index (BMI) were analyzed. RESULTS: The mean diameter of the ACL fovea was 16.1 mm in male patients and 14.3 mm in female patients, which were comparable to the previously reported values. There were significant positive correlations between the diameter of the ACL fovea and height and weight, but not BMI. The number of knees in which the diameter of the ACL fovea was <13 mm was 14 (14 %), and females were more likely to have ACL fovea diameter <13 mm. CONCLUSIONS: The study indicated that it is possible to predict the size of the ACL before surgery by measuring the diameter of the ACL fovea on MRI. Physical characteristics of patients correlated with the diameter of the ACL fovea. Especially in female patients, it is important to consider the size of the ACL preoperatively.