• MeSH
• Biomechanical Phenomena instrumentation   MeSH
• Walking MeSH
• Fluoroscopy methods   MeSH
• Humans MeSH
• Movement MeSH
• Prosthesis Design MeSH
• Arthroplasty, Replacement, Knee MeSH
• Imaging, Three-Dimensional MeSH
• Check Tag
• Humans MeSH

• MeSH
• Osteoarthritis, Knee radiography   MeSH
• Fluoroscopy methods   MeSH
• Clinical Medicine MeSH
• Cartilage, Articular physiopathology   radiography   MeSH
• Longitudinal Studies MeSH
• Publication type
• Collected Work MeSH

• Conspectus
• Patologie. Klinická medicína
• NML Fields
• ortopedie
• revmatologie
• radiologie, nukleární medicína a zobrazovací metody

Accurate assessment of 3D tibio-femoral kinematics is essential for understanding knee joint functionality, but also provides a basis for assessing joint pathologies and the efficacy of musculoskeletal interventions. Until now, however, the assessment of functional kinematics in healthy knees has been mostly restricted to the loaded stance phase of gait, and level walking only, but the most critical conditions for the surrounding soft tissues are known to occur during high-flexion activities. This study aimed to determine the ranges of tibio-femoral rotation and condylar translation as well as provide evidence on the location of the centre of rotation during multiple complete cycles of different gait activities. Based on radiographic images captured using moving fluoroscopy in ten healthy subjects during multiple cycles of level walking, downhill walking and stair descent, 3D femoral and tibial poses were reconstructed to provide a comprehensive description of tibio-femoral kinematics. Despite a significant increase in joint flexion, the condylar antero-posterior range of motion remained comparable across all activities, with mean translations of 6.3-8.3 mm and 7.3-9.3 mm for the medial and lateral condyles respectively. Only the swing phase of level walking and stair descent exhibited a significantly greater range of motion for the lateral over the medial compartment. Although intra-subject variability was low, considerable differences in joint kinematics were observed between subjects. The observed subject-specific movement patterns indicate that accurate assessment of individual pre-operative kinematics together with individual implant selection and/or surgical implantation decisions might be necessary before further improvement to joint replacement outcome can be achieved.

• MeSH
• Biomechanical Phenomena MeSH
• Gait MeSH
• Femur * diagnostic imaging   MeSH
• Knee Joint * MeSH
• Humans MeSH
• Range of Motion, Articular MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

OBJECTIVES: Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back - a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo. METHODS: The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m(2) (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities. RESULTS: During maximally flexed kneeling and lunging activities, the mean tibial internal rotation was 8° (standard deviation (sd) 6). At a mean 112° flexion (sd 16) during lunging, the medial and lateral condyles were a mean of 2 mm (sd 3) and 8 mm (sd 4) posterior to a transverse line passing through the centre of the medial tibial concavity. With a mean flexion of 117° (sd 14) during kneeling, the medial and lateral condyles were a mean of 1 mm (sd 4) anterior and 6 mm (sd 4) posterior to the same line. During dynamic stair and pivoting activities, there was a mean anteroposterior translation of 0 mm to 2 mm of the medial femoral condyle. Backward lateral condylar translation occurred and was linearly related to tibial rotation. CONCLUSION: The GMK Sphere TKA in our study group shows movements similar in pattern, although reduced in magnitude, to those in recent reports relating to normal knees during several activities. Specifically, little or no translation of the medial femoral condyle was observed during flexion, but there was posterior roll-back of the lateral femoral condyle, equating to tibiofemoral rotation. We conclude that the GMK Sphere is anteroposteriorly stable medially and permits rotation about the medial compartment.Cite this article: Professor G. Scott. Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?: A pulsed fluoroscopic investigation. Bone Joint Res 2016;5:80-86. DOI: 10.1302/2046-3758.53.2000621.

• Publication type
• Journal Article MeSH

Objectives: The medially spherical GMK Sphere (Medacta International AG, Castel San Pietro, Switzerland) total knee arthroplasty (TKA) was previously shown to accommodate lateral rollback while pivoting around a stable medial compartment, aiming to replicate native knee kinematics in which some coronal laxity, especially laterally, is also present. We assess coronal plane kinematics of the GMK Sphere and explore the occurrence and pattern of articular separation during static and dynamic activities. Methods: Using pulsed fluoroscopy and image matching, the coronal kinematics and articular surface separation of 16 well-functioning TKAs were studied during weight-bearing and non-weight-bearing, static, and dynamic activities. The closest distances between the modelled articular surfaces were examined with respect to knee position, and proportions of joint poses exhibiting separation were computed. Results: Overall, 1717 joint poses were analyzed. At a 1.0 mm detection threshold, 37 instances of surface separation were observed in the lateral compartment and four medially (p < 0.001). Separation was activity-dependent, both laterally and medially (p < 0.001), occurring more commonly during static deep flexion in the lateral compartment, and during static rotation in the medial compartment. Lateral separation occurred more frequently than medial during kneeling (7/14 lateral vs 1/14 medial; p = 0.031) and stepping (20/1022 lateral vs 0/1022 medial; p < 0.001). Separation varied significantly between individuals during dynamic activities. Conclusion: No consistent association between closest distances of the articular surfaces and knee position was found during any activity. Lift-off was infrequent and depended on the activity performed and the individual knee. Lateral separation was consistent with the design rationale. Medial lift-off was rare and mostly in non-weight-bearing activities.Cite this article: S. Key, G. Scott, J.G. Stammers, M. A. R. Freeman†, V. Pinskerova, R. E. Field, J. Skinner, S. A. Banks. Does lateral lift-off occur in static and dynamic activity in a medially spherical total knee arthroplasty? A pulsed-fluoroscopic investigation. Bone Joint Res 2019;8:207-215. DOI: 10.1302/2046-3758.85.BJR-2018-0237.R1.

• Publication type
• Journal Article MeSH

Joint stability is a primary concern in total knee joint replacement. The GMK Sphere prosthesis was specifically designed to provide medial compartment anterior-posterior (A-P) stability, while permitting rotational freedom of the joint through a flat lateral tibial surface. The objective of this study was to establish the changes in joint kinematics introduced by the GMK Sphere prosthesis during gait activities in comparison to conventional posterior-stabilized (PS) fixed-bearing and ultra-congruent (UC) mobile-bearing geometries. The A-P translation and internal/external rotation of three cohorts, each with 10 good outcome subjects (2.9 ± 1.6 years postop), with a GMK Sphere, GMK PS or GMK UC implant were analysed throughout complete cycles of gait activities using dynamic videofluoroscopy. The GMK Sphere showed the smallest range of medial compartment A-P translation for level walking, downhill walking, and stair descent (3.6 ± 0.9 mm, 3.1 ± 0.8 mm, 3.9 ± 1.3 mm), followed by the GMK UC (5.7 ± 1.0 mm, 8.0 ± 1.7 mm, 8.7 ± 1.9 mm) and the GMK PS (10.3 ± 2.2 mm, 10.1 ± 2.6 mm, 11.6 ± 1.6 mm) geometries. The GMK Sphere exhibited the largest range of lateral compartment A-P translation (12.1 ± 2.2 mm), and the largest range of tibial internal/external rotation (13.2 ± 2.2°), both during stair descent. This study has shown that the GMK Sphere clearly restricts A-P motion of the medial condyle during gait activities while still allowing a large range of axial rotation. The additional comparison against the conventional GMK PS and UC geometries, not only demonstrates that implant geometry is a key factor in governing tibio-femoral kinematics, but also that the geometry itself probably plays a more dominant role for joint movement than the type of gait activity. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2337-2347, 2019.

• MeSH
• Biomechanical Phenomena MeSH
• Gait * MeSH
• Fluoroscopy MeSH
• Cohort Studies MeSH
• Middle Aged MeSH
• Humans MeSH
• Knee Prosthesis * MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Observational Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH

Introduction: Less invasive restoration of joint congruity and calcaneal shape in displaced intra-articular calcaneal fractures via a sinus tarsi approach followed by percutaneous internal fixation with an interlocking nail results in a low rate of soft-tissue complications and good short-term outcomes1 (Video 1). Indications & Contraindications: Step 1 Patient Placement: Place the patient in the lateral decubitus position, supporting the involved extremity with a soft radiolucent pillow, flex the contralateral knee, check with fluoroscopy before draping, and obtain lateral radiographs. Step 2 Incision: Use a sinus tarsi approach for control of the articular reduction. Step 3 Percutaneous Manipulation of the Main Fragments: Percutaneously manipulate the main fragments to facilitate reduction of the main tuberosity fragment toward the sustentacular fragment and subsequent joint reduction. Step 4 Joint Reduction with Direct Manipulation of the Main Fragments through the Sinus Tarsi Approach: Reduce the joint with direct manipulation of the main fragments through the sinus tarsi approach. Step 5 Joint Fixation with Screws: Check the congruency of the posterior subtalar joint facet, stabilize the posterior facet with 2 screws, reduce the tuberosity against the joint block and anterior process, and temporarily fix with Kirschner wires. Step 6 Introduction of the Intramedullary Nail: Make a 10-mm vertical incision below the attachment of the Achilles tendon, direct the guidewire toward the center of the calcaneocuboid joint, place the guidewire centrally within the calcaneal body, ream over the guidewire, and introduce the intramedullary nail with the attached aiming device. Step 7 Locking of the Nail: Use the aiming device to position the proximal Kirschner wire into the sustentacular fragment, place the nail so that it hits the sustentaculum tali properly, insert a second Kirschner wire through the other hole of the guiding arm, exchange the wires after drilling for locking screws, apply an end cap to extend the length of nail, if needed, and then verify proper reduction and implant position fluoroscopically. Step 8 Postoperative Management: Manage the patient with continuous passive motion and active range-of-motion exercises of the ankle beginning on postoperative day 2 and allow partial weight-bearing of 20 kg for 6 to 10 weeks. Results: Recently, we reported on 103 patients with 106 intra-articular calcaneal fractures treated with the C-Nail by 4 senior surgeons from February 2011 to October 20131. Pitfalls & Challenges:

• Publication type
• Journal Article MeSH