The Influence of the Posterior Slope Angle and Posterior Condylar Offset in Posterior-Stabilized Total Knee Arthroplasty Was Analyzed From the Way of Constructing Flexion Gap

IntroductionThe purpose of this study was to compare the effects of two ways of establishing the flexion gap on the flexion angle and flexion-extension motion after posterior-stabilized （PS） prosthesis. A way for the posterior slope angle（PSA）and posterior condylar offset（PCO）were greater than preoperative, another for less than preoperative.Materials and MethodsThey are grouped according to the way flexion gaps are constructed. Data from 28 total knee arthroplasty（TKA）patients treated with propensity score match (PSM) were included. The difference of flexion angle and flexion-extension motion between the two groups was compared, and the influence of PCO and PSA on the flexion angle in the two ways was analyzed.ResultsPostoperative flexion degree of the two groups was 115.50±14.64° and 112.29±10.64° (P =0.553), and there was no statistical significance. Postoperative flexion-extension motion grade data of the decrease group was better than that of the increased group (P =0.031). Postoperative flexion angle was negatively correlated with PCO change in the increase group (r²=0.574 b '=-0.758 p=0.002).ConclusionsIncreasing the PSA and PCO to construct flexion gaps in PS TKA will cause problems with flexion-extension movements. It may be more reasonable to avoid excessive PSA and select appropriate PCO to reconstruct the flexion gap in PS prosthetic.

The posterior tibial slope is mainly created by the posterior rotation of the tibial condyles

Purpose: Constitutional varus in the coronal plane is formed based on the Hueter-Volkmann’s law. The varus deformity occurs at the proximal metaphysis of the tibia and the tibial condyle rotates medially. In the sagittal plane, we hypothesized that the posterior slope angle of the tibial articular surface may also occur at the proximal metaphysis and the tibial condyle rotates posteriorly. The purpose of this study was to verify the hypothesis. Methods: A total of 208 patients who underwent TKA had lateral view proximal tibia digital radiograph on which seven parameters were analyzed. The posterior slope angle of the tibial articular surface relative to the anterior wall of the tibial condyle and that relative to the anterior cortex of the tibial shaft were assessed. Correlation between the position of the tibial condyle and the posterior slope angle of the articular surface were assessed. Results: The proximal tibial condyle itself did not have a posterior slope in the 86.5% of the participants. Posterior rotation of the tibial condyle created posterior slope of the tibial articular surface relative to the anterior cortex of the tibial shaft. The more tibial condyle was posteriorly rotated, the more the tibial articular surface shifted posteriorly. Conclusion: Study findings showed that the posterior tibial slope occurs at the proximal metaphysis of the tibia, and the tibial condyle rotates posteriorly. The posterior tibial slope involves the posterior shift of the tibial articular surface. The posterior tibial slope is mainly created by the posterior rotation of the tibial condyle.

Clinical features and treatment of “Non-dislocated hyperextension tibial plateau fracture”

Background To explore the epidemiological characteristics, clinical characteristics, treatment strategies and clinical results of non-dislocated hyperextension tibial plateau fracture. Method A total of 25 cases of non-dislocated hyperextension tibial plateau fracture patients were collected, including 12 males and 13 females, aged 27-79 years. Preoperative tibial plateau posterior slope angle was - 10 ~ 0 degrees, average - 5.2 degrees. Preoperative MRI showed 5 cases of MCL injury, 3 cases of PLC complex injury and 2 cases of PLC + PCL injury. The change of tibial plateau posterior slope angle was more than 10 degrees in patients with ligament injury, and the patients with a tibial plateau posterior slope angle change less than 10 degrees had no ligament injury; 6 patients with simple column fracture had a ligament injury, 2 patients with bilateral column fracture had a ligament injury, and 2 patients with three column fracture had a ligament injury. Results All patients were followed up for 12-24 months (average 16.4 months). The operation time was 65-180 minutes (average 124 minutes), and the bleeding volume was 20-200 ml (average 106 ml). The plate was placed on the anterior part of tibial plateau. Evaluation of postoperative fracture reduction: 20 cases were anatomic reduction, 5 cases were good reduction (between 2-5mm articular surface collapse), and the excellent rate of fracture reduction was 100%. The fracture healing time was 3-6 months (average 3.3 months). The postoperative knee Rasmussen score was 18-29 (average 24.9), and the postoperative knee joint mobility was 90-130 ° (average 118 °). Superficial infection occurred in 2 patients. Conclusions The main imaging characteristic of "non-dislocated hyperextension tibial plateau fracture" is the change of tibial plateau posterior slope angle. The injury of single anteromedial column/anterolateral column fracture is easy to combine with "diagonal" injury, and when the tibial plateau posterior slope angle changes more than 10 degrees, it is easy to be associated with ligament injury. By restoring the joint articular surface and lower limb force line, repairing the soft tissue structure, and reconstructing the knee joint stability, we can achieve satisfactory results.

Ángulo de pendiente tibial posterior “Slope” en prótesis total de rodilla. Diferencias entre alineación Intra o Extramedular y su repercusión sobre el rango de movilidad postoperatorio.

Introduction: The aim of this work was to compare the posterior tibial slope of the tibial component after performing a total knee arthroplasty, as an intramedullary or extramedullary guide was used during the surgical technique, as well as comparing the range of mobility obtained according to the Instrumentation used. Material and methods: We conducted a descriptive, retrospective, observational study of a series of 57 patients operated in our Center during 2012 and 2013, with the same model of total knee arthroplasty (Sigma PS® DePuy), divided into two homogeneous groups in terms of age, sex, degree of osteoarthritis evolution, the first with patients operated by extramedullary guidance and the second by intramedullary guidance. A radiographic study was performed, measuring the posterior slope angle in the sagittal plane. The range of mobility achieved after arthroplasty and implant survival was studied. Results: Together, in both groups, measurements of the posterior slope angle were made, which was 4.35º preoperative average. In groups, the mean postoperative posterior fall angle was 4.04 ° in the patients who underwent an EM guide, while those who underwent an IM guide the mean was 1.76 °; the differences being statistically significant. The range of mobility in the ATRs operated by intramedullary guidance was 102.7º on average (range 80-125º), while in the group where the extramedullary guide was used, it was 104.3º (range 80-130º) no these differences being statistically significant. Regarding the survival of the implant, during the study period two cases of patients undergoing surgery for the replacement of prostheses were found, both of which belonged to the “Extramedullary guide” group. Conclusion: The posterior drop angle, for the same PS prosthesis model, was statistically different according to the guide used, being within the 3-7º range in the group where the extramedullary guide was used; but despite these differences, no impact on the range of mobility was observed. Currently, it is recommended to restore the patient's posterior tibial slope, and in cases with a slope greater than 10º use a PS ATR.

MRI in idiopathic, stable, slipped capital femoral epiphysis: evaluation of contralateral pre-slip

Purpose Early diagnosis and treatment of slipped capital femoral epiphysis (SCFE) is important to prevent slip progression and avoid complications. We sought to determine if MRI findings in patients with unilateral SCFE could indicate ‘pre-slip’ or predict future SCFE in the contralateral hip. Methods A prospective study evaluated patients with unilateral SCFE over a two-year period. MRI of the asymptomatic hip was performed within the perioperative period. Patients were followed with radiographs until a contralateral slip occurred or until physeal closure. Demographics, clinical stability, severity, posterior slope angle (PSA), modified Oxford Bone Score (mOBS) and patency of the triradiate cartilage were recorded and statistical analysis performed. Results In all, 33 of 54 patients with unilateral SCFE were enrolled into the study. In all, 29 (87.8%) had complete follow-up. Five of the enrolled patients (15.2%) developed a sequential slip requiring in situ pinning. Six of 33 (18.2%) patients had positive MRI findings: four of which proceeded to sequential SCFE and two which did not. One sequential slip had a negative MRI. PSA predicted 1/11 sequential slips (sensitivity 9.09%, specificity 81.4%, positive predictive value (PPV) 11.1%, negative predictive value (NPV) 77.8%) and mOBS predicted 5/11 sequential slips (sensitivity 45.5%, specificity 93%, PPV 62.5%, NPV 87%). An open triradiate cartilage was present in 8/11 patients with sequential slips (sensitivity 72.7%, specificity 81.4%, PPV 50%, NPV 92.1%). Conclusion MRI findings consistent with ‘pre-slip’ were present in 66.7% of patients who developed a sequential SCFE. Further study on the utility/sensitivity of MRI in predicting sequential SCFE is warranted. Level of Evidence II, diagnostic