Aims. The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation. Methods. We constructed a computer model of knee arthroplasty and used a virtual cutting guide to cut the tibia at 90° to the coronal plane. The virtual guide was rotated axially (15° medial to 15° lateral) and with
Aims. This study aims to investigate the effects of
Abstract. Purpose. Recently several authors have suggested a correlation between
Abstract. Introduction. High
Abstract. Introduction. Changes in
The purpose of this study was to evaluate 3 methods used to produce
We performed a CT-based computer simulation study
to determine how the relationship between any inbuilt posterior
slope in the proximal tibial osteotomy and cutting jig rotational
orientation errors affect tibial component alignment in total knee
replacement. Four different
The optimal management of the tibial slope in
achieving a high flexion angle in posterior-stabilised (PS) total
knee replacement (TKR) is not well understood, and most studies
evaluating the
Objectives. Posterior condylar offset (PCO) and
The aim of this study was to investigate the long-term clinical
and radiological outcome of patients who suffer recurrent injuries
to the anterior cruciate ligament (ACL) after reconstruction and
require revision surgery. From a consecutive series of 200 patients who underwent primary
reconstruction following rupture of the ACL, we identified 36 who
sustained a further rupture, 29 of whom underwent revision surgery.
Patients were reviewed prospectively at one, two, seven, 15 and
about 20 years after their original surgery. Primary outcome measures
were the number of further ruptures, the posterior tibial slope
(PTS), and functional and radiological outcomes. These were compared
with a gender and age matched cohort of patients who underwent primary
ACL reconstruction only.Aims
Patients and Methods
Aims. A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different
Aims. Unicompartmental knee arthroplasty (UKA) has become a popular method of treating knee localized osteoarthritis (OA). Additionally, the posterior cruciate ligament (PCL) is essential to maintaining the physiological kinematics and functions of the knee joint. Considering these factors, the purpose of this study was to investigate the biomechanical effects on PCL-deficient knees in medial UKA. Methods. Computational simulations of five subject-specific models were performed for intact and PCL-deficient UKA with tibial slopes. Anteroposterior (AP) kinematics and contact stresses of the patellofemoral (PF) joint and the articular cartilage were evaluated under the deep-knee-bend condition. Results. As compared to intact UKA, there was no significant difference in AP translation in PCL-deficient UKA with a low flexion angle, but AP translation significantly increased in the PCL-deficient UKA with high flexion angles. Additionally, the increased AP translation became decreased as the
Aims. Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA. Methods. A total of 220 consecutive primary TKAs between May 2016 and November 2018, performed by a single surgeon, were reviewed. Planned coronal plane component alignment and overall limb alignment were all 0° to the mechanical axis; tibial
Objectives. Unicompartmental knee arthroplasty (UKA) is one surgical option for treating symptomatic medial osteoarthritis. Clinical studies have shown the functional benefits of UKA; however, the optimal alignment of the tibial component is still debated. The purpose of this study was to evaluate the effects of tibial coronal and sagittal plane alignment in UKA on knee kinematics and cruciate ligament tension, using a musculoskeletal computer simulation. Methods. The tibial component was first aligned perpendicular to the mechanical axis of the tibia, with a 7°
Introduction. Malalignment of total knee arthroplasty components may affect implant function and lead to decreased survival, regardless of preferred alignment philosophy – neural mechanical axis restoration or kinematic alignment. A common technique is to set coronal alignment prior to adjusting slope. If the guide is not maintained in a neutral position, adjustment of the slope may alter coronal alignment. Different implant systems recommend varying degrees of slope for ideal function of the implant, from 0–7°. The purpose of this study was to quantify the change in coronal alignment with increasing
Aims. The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. Methods. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. Results. There were evident biomechanical differences between the simulated patient models, but also trends that appeared reproducible at the population level. Optimizing the implant position significantly reduced the maximum observed strain root mean square deviations within the cohort from 36.5% to below 5.3% for all but the anterolateral ligament; and concomitantly reduced the kinematic deviations from 3.8 mm (SD 1.7) and 4.7° (SD 1.9°) with MA to 2.7 mm (SD 1.4) and 3.7° (SD 1.9°) relative to the pre-diseased state. To achieve this, the femoral component consistently required translational adjustments in the anterior, lateral, and proximal directions, while the tibial component required a more
Abstract. Introduction. OtisMed Shape Match ® patient specific implant cutting jigs were designed to place TKA in kinematic alignment (KA) rather than traditional mechanical alignment (MA). This product was withdrawn from the market in 2013. It has been hypothesised that KA might lead to early implant failure. Initial evidence has not supported this. We present 10 year outcome data for the largest single centre cohort to date. Methodology. Between 2010 and 2013, 127 Shape Match® TKAs were implanted in 119 individuals. Retrospective review of long leg post-operative radiographs assessed femoral mechanical anatomical angle (FMA), tibial mechanical angle (TMA), hip-knee-ankle angle (HKA),
Introduction. Robot-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to quantify soft tissue laxity and adjust the plan prior to bone resection should reduce variability in polyethylene thickness. This study was performed to compare accuracy to plan for component positioning and polyethylene thickness in RA-TKA versus M-TKA. Methods. 199 consecutive primary TKAs (96 C-TKA and 103 RA-TKA) performed by a single surgeon were reviewed. Full-length standing and knee radiographs were obtained pre and post-operatively. For M-TKA, measured resection technique was used. Planned coronal plane femoral and tibial component alignment, and overall limb alignment were all 0° to the mechanical axis; tibial
Introduction. Implant malalignment is an important predictor of prosthetic failure following total knee arthroplasty (TKA). The purpose of this study was to determine the incidence of outliers for common alignment targets and the impact of surgeon volume and experience on the accuracy of implant alignment with current generation manual instrumentation. Methods. This study was a retrospective, multi-center, radiographic analysis of 1675 consecutive primary uncomplicated TKAs from seven surgeons at three academic and state-funded centers in the US and UK. Surgeons were categorized as “high-volume” (≥50 TKAs/year) and “high-experience” (≥5 years post-fellowship). Femorotibial, tibial varus/valgus, and
Introduction. The relationship between sagittal component alignment on clinical outcomes has not fully evaluated after TKA. This study evaluated the effect of sagittal alignment of the components on patient function and satisfaction as well as kinematics and kinetics. Methods. This study included 148 primary TKAs with cruciate-substituting prosthesis for primary OA. With post-operative lateral radiograph, femoral component flexion angle (γ) and tibial component