We previously compared the component alignment in total knee replacement using a computer-navigated technique with a conventional jig-based method. We randomly allocated 71 patients to undergo either computer-navigated or conventional replacement. An improved alignment was seen in the computer-navigated group. The patients were then followed up post-operatively for two years, using the Knee Society score, the Short Form-36 health survey, the Western Ontario and McMaster Universities osteoarthritis index, the Bartlett Patellar pain questionnaire and the Oxford knee score, to assess functional outcome. At two years post-operatively 60 patients were available for assessment, 30 in each group and 62 patients completed a postal survey. No patient in either group had undergone revision. All variables were analysed for differences between the groups either by Student’s The clinical outcome of the patients with a computer-navigated knee replacement appears to be no different to that of a more conventional jig-based technique at two years post-operatively, despite the better alignment achieved with computer-navigated surgery.
We performed a randomised controlled trial comparing
computer-assisted surgery (CAS) with conventional surgery (CONV)
in total knee replacement (TKR). Between 2009 and 2011 a total of
192 patients with a mean age of 68 years (55 to 85) with osteoarthritis
or arthritic disease of the knee were recruited from four Norwegian
hospitals. At three months follow-up, functional results were marginally
better for the CAS group. Mean differences (MD) in favour of CAS
were found for the Knee Society function score (MD: 5.9, 95% confidence
interval (CI) 0.3 to 11.4, p = 0.039), the Knee Injury and Osteoarthritis
Outcome Score (KOOS) subscales for ‘pain’ (MD: 7.7, 95% CI 1.7 to
13.6, p = 0.012), ‘sports’ (MD: 13.5, 95% CI 5.6 to 21.4, p = 0.001)
and ‘quality of life’ (MD: 7.2, 95% CI 0.1 to 14.3, p = 0.046).
At one-year follow-up, differences favouring CAS were found for
KOOS ‘sports’ (MD: 11.0, 95% CI 3.0 to 19.0, p = 0.007) and KOOS
‘symptoms’ (MD: 6.7, 95% CI 0.5 to 13.0, p = 0.035). The use of
CAS resulted in fewer outliers in frontal alignment (>
3° malalignment),
both for the entire TKR (37.9% Cite this article:
The restoration of knee alignment is an important
goal during total knee arthroplasty (TKA). In the past surgeons aimed
to restore neutral limb alignment during surgery. However, previous
studies have demonstrated alignment to be dynamic, varying depending
on the position of the limb and the degree of weight-bearing, and
between patients. We used a validated
Aims. Neither a surgeon’s intraoperative impression nor the parameters of
Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre. Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A sub-cohort of 250 radiographs were annotated for landmarks relevant to knee alignment and used to train a deep learning (U-Net) workflow for angle calculation on the entire database. The radiological ankle centre was defined as the midpoint of the superior talus edge/tibial plafond. Knee alignment (hip-knee-ankle angle) was compared against 1) midpoint of the most prominent malleoli points, 2) midpoint of the soft-tissue overlying malleoli, and 3) midpoint of the soft-tissue sulcus above the malleoli.Aims
Methods
Substantial healthcare resources have been devoted
to
Improvements in the surgical technique of total
knee replacement (TKR) are continually being sought. There has recently
been interest in three-dimensional (3D) pre-operative planning using
magnetic resonance imaging (MRI) and CT. The 3D images are increasingly
used for the production of patient-specific models, surgical guides
and custom-made implants for TKR. The users of patient-specific instrumentation (PSI) claim that
they allow the optimum balance of technology and conventional surgery
by reducing the complexity of conventional alignment and sizing
tools. In this way the advantages of accuracy and precision claimed
by
There are several methods for evaluating stability
of the joint during total knee replacement (TKR). Activities of daily
living demand mechanical loading to the knee joint, not only in
full extension, but also in mid-flexion. The purpose of this study
was to compare the varus-valgus stability throughout flexion in
knees treated with either cruciate-retaining or posterior-stabilised
TKR, using an intra-operative navigation technique. A total of 34
knees underwent TKR with
Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.
Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model. We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition.Aims
Methods
Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice. This retrospective cohort study included consecutive patients undergoing TKA at a specialist centre in the UK between November 2010 and December 2012. Data were collected using a bespoke electronic database and cross-referenced with national arthroplasty audit data, with variables including: preoperative characteristics, intraoperative factors, complications, and mortality status. Patient-reported outcome measures (PROMs) were collected by a specialist research team at ten years post-surgery. There were 536 TKAs, of which 308/536 (57.5%) were in female patients. The mean age was 69.0 years (95% CI 45.0 to 88.0), the mean BMI was 32.2 kg/m2 (95% CI 18.9 to 50.2), and 387/536 (72.2%) survived to ten years. There were four revisions (0.7%): two deep infections (requiring debridement and implant retention), one aseptic loosening, and one haemosiderosis.Aims
Methods
We describe the mid-term results of a prospective study of total knee replacement in severe valgus knees using an osteotomy of the lateral femoral condyle and
It is unknown whether gap laxities measured in robotic arm-assisted total knee arthroplasty (TKA) correlate to load sensor measurements. The aim of this study was to determine whether symmetry of the maximum medial and lateral gaps in extension and flexion was predictive of knee balance in extension and flexion respectively using different maximum thresholds of intercompartmental load difference (ICLD) to define balance. A prospective cohort study of 165 patients undergoing functionally-aligned TKA was performed (176 TKAs). With trial components in situ, medial and lateral extension and flexion gaps were measured using robotic navigation while applying valgus and varus forces. The ICLD between medial and lateral compartments was measured in extension and flexion with the load sensor. The null hypothesis was that stressed gap symmetry would not correlate directly with sensor-defined soft tissue balance.Aims
Methods
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. 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 posterior slopes (0° to 7°). To assess the effect of axial malrotation, we measured the coronal plane alignment of a tibial tray that was axially rotated (25° internal to 15° external), as viewed on a standard anteroposterior (AP) radiograph.Aims
Methods
Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment. A total of 121 consecutive TKAs performed between 11 February 2018 to 11 June 2019 with preoperative varus deformity were reviewed at minimum one-year follow-up. Three knees were excluded due to severe preoperative varus deformity greater than 15°, and a further three due to requiring revision surgery, leaving 109 patients and 115 knees to undergo primary TKA using the concept of restricted kinematic alignment with advanced technology. Patients were stratified into three groups based on the preoperative limb varus deformity: Group A with 1° to 5° varus (43 knees); Group B between 6° and 10° varus (56 knees); and Group C with varus greater than 10° (16 knees). This study group was compared with a matched cohort of 115 TKAs and 115 patients using a neutral mechanical alignment target with manual instruments performed from 24 October 2016 to 14 January 2019.Aims
Methods
The primary aim of this study was to compare the postoperative systemic inflammatory response in conventional jig-based total knee arthroplasty (conventional TKA) versus robotic-arm assisted total knee arthroplasty (robotic TKA). Secondary aims were to compare the macroscopic soft tissue injury, femoral and tibial bone trauma, localized thermal response, and the accuracy of component positioning between the two treatment groups. This prospective randomized controlled trial included 30 patients with osteoarthritis of the knee undergoing conventional TKA versus robotic TKA. Predefined serum markers of inflammation and localized knee temperature were collected preoperatively and postoperatively at six hours, day 1, day 2, day 7, and day 28 following TKA. Blinded observers used the Macroscopic Soft Tissue Injury (MASTI) classification system to grade intraoperative periarticular soft tissue injury and bone trauma. Plain radiographs were used to assess the accuracy of achieving the planned postioning of the components in both groups.Aims
Methods
The mobile bearing Oxford unicompartmental knee arthroplasty (OUKA) is recommended to be performed with the leg in the hanging leg (HL) position, and the thigh placed in a stirrup. This comparative cadaveric study assesses implant positioning and intraoperative kinematics of OUKA implanted either in the HL position or in the supine leg (SL) position. A total of 16 fresh-frozen knees in eight human cadavers, without macroscopic anatomical defects, were selected. The knees from each cadaver were randomized to have the OUKA implanted in the HL or SL position.Aims
Methods
This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes. A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle.Aims
Methods
As the population ages, there is projected to be an increase in the level of demand for total knee arthroplasty (TKA) in octogenarians. We aimed to explore whether those aged ≥ 80 years achieved similar improvements in physical function to younger patients while also comparing the rates of length of stay (LOS), discharge to rehabilitation, postoperative complications, and mortality following TKA in older and younger patients. Patients from one institution who underwent primary elective TKA between 1 January 2006 and 31 December 2014 were dichotomized into those ≥ 80 years old (n = 359) and those < 80 years old (n = 2479) for comparison. Multivariable regression was used to compare the physical status component of the 12-Item Short-Form Health Survey (SF-12), LOS, discharge to rehabilitation, complications, and mortality between the two groups.Aims
Patients and Methods
There has been a significant reduction in unicompartmental knee arthroplasty (UKA) procedures recorded in Australia. This follows several national joint registry studies documenting high UKA revision rates when compared to total knee arthroplasty (TKA). With the recent introduction of robotically assisted UKA procedures, it is hoped that outcomes improve. This study examines the cumulative revision rate of UKA procedures implanted with a newly introduced robotic system and compares the results to one of the best performing non-robotically assisted UKA prostheses, as well as all other non-robotically assisted UKA procedures. Data from the Australian Orthopaedic Association National Joint Arthroplasty Registry (AOANJRR) for all UKA procedures performed for osteoarthritis (OA) between 2015 and 2018 were analyzed. Procedures using the Restoris MCK UKA prosthesis implanted using the Mako Robotic-Arm Assisted System were compared to non-robotically assisted Zimmer Unicompartmental High Flex Knee System (ZUK) UKA, a commonly used UKA with previously reported good outcomes and to all other non-robotically assisted UKA procedures using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship.Aim
Methods