The influence of computer-assisted surgery on rotational, coronal and sagittal alignment in revision total knee arthroplasty

BACKGROUND: Despite good results of primary total knee arthroplasty (TKA), the number of revision total knee arthroplasties (rTKAs) is rising. Proper implant position is essential, since malposition leads to worse clinical outcome. In rTKA most anatomical landmarks have disappeared because of extensive bone loss, making it more difficult to adequately implant the knee prosthesis. In primary TKA, computer-assisted surgery (CAS) leads to better prosthetic alignment than mechanical navigation guides. Literature about the use of CAS in rTKA is scarce though, and the effect on rotational prosthetic alignment has not been investigated yet. Hence the primary objective of this study is to compare rotational prosthetic alignment when using CAS in rTKA compared to a mechanical navigation guide. Secondary objectives are to compare prosthetic alignment in the coronal and sagittal planes. It is hypothesized that CAS leads to better rotational, coronal and sagittal prosthetic alignment when used during rTKA. METHODS/DESIGN: A prospective clinical intervention study with use of a historical control group will be conducted. Forty-four patients with a minimum age of 18 to be admitted for CAS-rTKA between September 2012 and September 2015 will be included in the intervention group. Forty-four patients with a minimum age of 18 who underwent rTKA with the use of a mechanical navigation guide between January 2002 and April 2012 will form the historical control group. Both groups will be matched according to gender and type of revision prosthesis. Rotational prosthesis alignment will be evaluated using a CT-scan of the knee joint. DISCUSSION: Proper implant position is essential, since malposition leads to worse clinical outcome. Several studies show a significantly positive influence of CAS on prosthetic alignment in primary TKA, but literature about the use of CAS in rTKA is limited. The purpose of this study is thus to investigate the influence of CAS during rTKA on postoperative prosthetic alignment, compared to mechanical navigation guides. TRIAL REGISTRATION: Netherlands National Trial Register NTR351

Should all hip and knee prosthetic joints be aspirated prior to revision surgery?

Aims It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery. Methods We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria. Results A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%). Conclusion Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection

The Validity of a New Low-Dose Stereoradiography System to Perform 2D and 3D Knee Prosthetic Alignment Measurements

INTRODUCTION:The EOS stereoradiography system has shown to provide reliable varus/valgus (VV) measurements of the lower limb in 2D (VV2D) and 3D (VV3D) after total knee arthroplasty (TKA). Validity of these measurements has not been investigated yet, therefore the purpose of this study was to determine validity of EOS VV2D and VV3D. METHODS:EOS images were made of a lower limb phantom containing a knee prosthesis, while varying VV angle from 15° varus to 15° valgus and flexion angle from 0° to 20°, and changing rotation from 20° internal to 20° external rotation. Differences between the actual VV position of the lower limb phantom and its position as measured on EOS 2D and 3D images were investigated. RESULTS:Rotation, flexion or VV angle alone had no major impact on VV2D or VV3D. Combination of VV angle and rotation with full extension did not show major differences in VV2D measurements either. Combination of flexion and rotation with a neutral VV angle showed variation of up to 7.4° for VV2D; maximum variation for VV3D was only 1.5°. A combination of the three variables showed an even greater distortion of VV2D, while VV3D stayed relatively constant. Maximum measurement difference between preset VV angle and VV2D was 9.8°, while the difference with VV3D was only 1.9°. The largest differences between the preset VV angle and VV2D were found when installing the leg in extreme angles, for example 15° valgus, 20° flexion and 20° internal rotation. CONCLUSIONS:After TKA, EOS VV3D were more valid than VV2D, indicating that 3D measurements compensate for malpositioning during acquisition. Caution is warranted when measuring VV angle on a conventional radiograph of a knee with a flexion contracture, varus or valgus angle and/or rotation of the knee joint during acquisition

Mid-term results of the Latitude primary total elbow arthroplasty

Background: The Latitude total elbow prosthesis is a third-generation implant, developed to restore the natural anatomy of the elbow. Literature on this prosthesis is scarce. The aim of this study was to analyze the mid-term results of the Latitude total elbow prosthesis. Methods: We retrospectively evaluated 62 patients (21 men and 41 women). The mean age at the time of surgery was 65 years (range, 28-87 years). The main indication for surgery was inflammatory arthritis. The outcome measures were complications, reoperations, self-reported physical functioning, pain, satisfaction, objectively measured physical functioning, and radiologic signs of loosening. Kaplan-Meier survival analysis was used to determine survival with revision as the endpoint. Results: Sixty-nine primary Latitude prostheses were placed in 62 patients between 2008 and 2019. Six patients (7 prostheses) died, 3 elbows underwent revision, and 9 patients were lost to follow-up. A total of 44 patients (50 prostheses) were available for follow-up. The mean length of follow-up was 51 months (range, 10-144 months). Kaplan-Meier survival analysis showed a survival rate of 82% at 10 years after surgery. The main reason for revision was aseptic loosening. Radial head dissociation was seen in 8 patients (24%), but none had complaints. Self-reported and objectively measured physical functioning yielded good results, although 23 patients (46%) did show radiolucent lines on radiographs. Conclusion: Latitude total elbow arthroplasty is considered a successful procedure with low pain scores, high patient satisfaction, and good physical functioning. Survival rates nonetheless remain low and complication rates remain high yet are comparable to those of other elbow arthroplasties. We recommend biomechanical studies to concentrate on specific postoperative loading instructions to minimize wear and consequent loosening

Assessment of Prosthesis Alignment after Revision Total Knee Arthroplasty Using EOS 2D and 3D Imaging:A Reliability Study

INTRODUCTION: A new low-dose X-ray device, called EOS, has been introduced for determining lower-limb alignment in 2D and 3D. Reliability has not yet been assessed when using EOS on lower limbs containing a knee prosthesis. Therefore purpose of this study was to determine intraobserver and interobserver reliability of EOS 2D and 3D knee prosthesis alignment measurements after revision total knee arthroplasty (rTKA). METHODS: Forty anteroposterior and lateral images of 37 rTKA patients were included. Two observers independently performed measurements on these images twice. Varus/valgus angles were measured in 2D (VV2D) and 3D (VV3D). Intraclass correlation coefficients and the Bland and Altman method were used to determine reliability. T-tests were used to test potential differences. RESULTS: Intraobserver and interobserver reliability were excellent for VV2D and VV3D. No significant difference or bias between the first and second measurements or the two observers was found. A significant mean and absolute difference of respectively 1.00° and 1.61° existed between 2D and 3D measurements. CONCLUSIONS: EOS provides reliable varus/valgus measurements in 2D and 3D for the alignment of the knee joint with a knee prosthesis. However, significant differences exist between varus/valgus measurements in 2D and 3D

Do CAS measurements correlate with EOS 3D alignment measurements in primary TKA?

PURPOSE: Objective of this study was to compare intraoperative computer-assisted surgery (CAS) alignment measurements during total knee arthroplasty (TKA) with pre- and postoperative coronal alignment measurements using EOS 3D reconstructions. METHODS: In a prospective study, 56 TKAs using imageless CAS were performed and coronal alignment measurements were recorded twice: before bone cuts were made and after implantation of the prosthesis. Pre- and postoperative coronal alignment measurements were performed using EOS 3D reconstructions. Thanks to the EOS radiostereography system, measurement errors due to malpositioning and deformity during acquisition are eliminated. CAS measurements were compared with EOS 3D reconstructions. Varus/valgus angle (VV), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured. RESULTS: Significantly different VV angles were measured pre- and postoperatively with CAS compared to EOS. For preoperative measurements, mLDFA did not differ significantly, but a significantly larger mMPTA in valgus was measured with CAS. CONCLUSION: Results of this study indicate that differences in alignment measurements between CAS measurements and pre- and postoperative EOS 3D are due mainly to the difference between weight-bearing and non-weight-bearing position and potential errors in validity and reliability of the CAS system. EOS 3D measurements overestimate VV angle in lower limbs with substantial mechanical axis deviation. For lower limbs with minor mechanical axis deviation as well as for mMPTA measurements, CAS measures more valgus than EOS. Eventually the results of this study are of clinical relevance, since it raises concerns regarding the validity and reliability of CAS systems in TKA. LEVEL OF EVIDENCE: IIb

Elbow Joint Loads during Simulated Activities of Daily Living:Implications for Formulating Recommendations after Total Elbow Arthroplasty.

Background: Overloading of the elbow joint prosthesis following total elbow arthroplasty can lead to implant failure. Joint moments during daily activities are not well-contextualized for a prosthesis' failure limits and the effect of the current postoperative instruction on elbow joint loading is unclear. This study investigates the difference in elbow joint moments between simulated daily tasks and between flexion-extension, pronation-supination, varus-valgus movement directions. Additionally, the effect of the current postoperative instruction on elbow joint load is examined.Methods: Nine healthy participants (age 45.8 ± 17 years, 3 males) performed eight tasks; driving a car, opening a door, rising from chair, lifting, sliding, combing hair, drinking, emptying cup, without and with the instruction "not lifting more than 1 kg". Upper limb kinematics and hand contact forces were measured. Elbow joint angles and net moments were analyzed using inverse dynamic analysis, where the net moments are estimated from movement data and external forces.Results: Peak elbow joint moments differed significantly between tasks (p &lt; 0.01) and movement directions (p &lt; 0.01). The most and least demanding tasks were, rising from a chair (13.4 Nm extension, 5.0 Nm supination, 15.2 Nm valgus) and sliding (4.3 Nm flexion, 1.7 Nm supination, 2.6 Nm varus). Net moments were significantly reduced after instruction only in the chair task (p &lt; 0.01).Conclusion: This study analyzed elbow joint moments in different directions during daily tasks. The outcomes question whether postoperative instruction can lead to decreasing elbow loads. Future research might focus on reducing elbow loads in the flexion-extension and varus-valgus directions.<br/