The objective of this study was to evaluate the kinematics of a high-flexion, posterior-stabilized total knee arthroplasty (TKA) in weight-bearing, deep knee bending motion. Fifteen patients implanted with the Legacy Posterior Stabilized Flex (8; mobile bearing and 7; fixed bearing), 18 patients with Scorpio NRG, and 8 patients with PFC sigma RP-F were examined during a deep knee bending motion using fluoroscopy. Femorotibial motion was determined using a 2-dimensional to 3-dimensional registration technique, which used computer-assisted design models to reproduce the position of metallic implants from single-view fluoroscopic images. The average flex-ion ranges of motion between the metallic implants were 120° with Legacy Flex, 125° with NRG and 121° with RP-F. The average rotation of the femoral component was 11° external rotation (ER) with Legacy Flex, 12° with NRG and 11° with RP-F. The mean kinematic pathways were early rollback, lateral pivot with ER, and bicondylar rollback with Legacy Flex, medial pivot with ER and bicondylar rollback with NRG and central pivot with ER and bicondylar rollback with RP-F. The in vivo kinematics was different due to the
This study compared patient-reported outcomes of three total knee arthroplasty (TKA) designs from one manufacturer: one cruciate-retaining (CR) design, and two cruciate-sacrificing designs, anterior-stabilized (AS) and posterior-stabilized (PS). Patients scheduled for primary TKA were included in a single-centre, prospective, three-armed, blinded randomized trial (n = 216; 72 per group). After intraoperative confirmation of posterior cruciate ligament (PCL) integrity, patients were randomly allocated to receive a CR, AS, or PS design from the same TKA system. Insertion of an AS or PS design required PCL resection. The primary outcome was the mean score of all five subscales of the Knee injury and Osteoarthritis Outcome Score (KOOS) at two-year follow-up. Secondary outcomes included all KOOS subscales, Oxford Knee Score, EuroQol five-dimension health questionnaire, EuroQol visual analogue scale, range of motion (ROM), and willingness to undergo the operation again. Patient satisfaction was also assessed.Aims
Methods
In this 2-year randomised clinical trial we examined whether cemented femoral prosthesis geometry affects the pattern of strain-adaptive bone remodelling in the proximal femur after THA. 128 patients undergoing primary THA were randomised to receive a Charnley (shape-closed, no taper), Exeter (force-closed, double-tapered) or C-stem (forced-closed, triple-tapered) prosthesis. All received a cemented Charnley cup. Proximal femoral BMD change over 2 years was measured by DXA. Urine and serum samples were collected at pre-operative baseline and over 1 year post-operatively. N-telopeptides of type-I-collagen (NTX) was measured in urine as a marker of osteoclast activity and Osteocalcin (OC) in serum as a maker of osteoblast activity. Clinical outcome using the Harris and Oxford hip scores, and prosthesis migration measured using digitised radiographs (EBRA-Digital) were measured over 2 years. The baseline characteristics of the subjects in each group were similar (P>
0.05). Decreases in femoral BMD were observed over the first year for all
Objective. Tibia vara seen in Japanese patients reportedly influences the tibial component alignment when performing TKA. However, it is unclear whether tibia vara affects the component position and size selection. We therefore determined (1) the amount of medial tibial bow, (2) whether the tibia vara influences the aspect ratio of the tibial resected surface in aligning the tibial component with the tibial shaft axis (TSA), and (3) whether currently available tibial components fit the shapes of resected proximal tibias in terms of aspect ratio. Material and Methods. The study was performed using CT data from 90 lower limbs in 74 Japanese female patients with primary varus knee OA, scheduled for primary TKAs between January 2010 and March 2012. We measured the tibia vara angle (TVA; the angle between the TSA and the tibial mechanical axis), proximal varus angle (PVA; angle between the TSA and the line connecting the center of the tibial eminence and the center of the proximal 1/3 of the tibia) using three-dimensional preoperative planning software [Fig.1]. Then the mediolateral and middle AP dimensions of the resected surface when the tibial component was set so that its center aligned with the TSA was measured. We determined the correlations of the aspect ratio (the ML dimension divided by the AP dimension) of the resected surface with TVA or PVA and compared the aspect ratios to those of five
Purpose: There is no data concerning morphological dimensions of distal femur(DF), proximal tibia(PT) and thickness of patella(TP) in Indian population and our objective was to analyse the anthropometric data in Indian knees and to correlate them with existing knee arthroplasty systems. Methods: MRI scans of 25 patients(15M;10F) who underwent bilateral knee scans for ligamental injuries were collected. Patients with arthritis, bone loss, varus/ valgus deformity of >
150 and those with immature skeleton were excluded. The mean age was 32 years (range 18–53y). Three surgeons independently measured medio-lateral(ML), antero-posterior(AP) lengths &
aspect ratio(AR) of DF, PT and TP on three occasions one week apart to account for intra &
inter-observer variability. The resultant data of 50 knees was analysed using SPSS v16.0 and compared with five different knee arthroplasty systems (PFC sigma/NexGen/Scorpio/IB-II/ Gender specific knee). Results: The mean ML &
AP for proximal tibia was 73.3±5.3 &
47.8±4.3 mm. The mean ML &
AP (lateral condyle) for distal femur was 74.3±5.9 &
65.4±5.0 mm. The mean unresected thickness of patella was 24.7 &
21.8 mm in males &
females respectively. The ML &
AP showed a statistically significant positive correlation with person’s height (ML®=0.55;AP®=0.50 &
p=0.01). A decrease in AR for increasing AP dimension was noted for both distal femur and proximal tibia (Tibia®=0.153;p=0.29 &
Femur:®=−0.91;p=0.001). Discussion: None of the
There is no data concerning morphological dimensions of distal femur, proximal tibia and patella in Indian population. The objective was to analyse the anthropometric data in Indian knees and to co-relate them with existing knee arthroplasty systems. MRI scans of 25 patients (15 males &
10 females) who underwent bilateral knee scans for ligamental injuries were collected. Patients with arthritis, bone loss, varus/valgus deformity of >
15 degrees and those with immature skeleton were excluded. The mean age was 32 yrs (18–53 yrs). Three surgeons independently measured medio-lateral (ML), antero-posterior(AP) dimensions &
aspect ratio(AR) of distal femur, proximal tibia and unresected patellar thickness(PT) on three occasions one week apart to account for intra &
inter-observer variability. The resultant data of 50 knees was analysed using SPSS v14.0 and compared with five prosthesis knee systems (PFC sigma, NexGen, Scorpio, IB-II &
Gender specific knee). The mean ML &
AP for proximal tibia was 73.3±5.3 &
47.8±4.3 mm. The mean ML &
AP (lateral condyle) for distal femur was 74.3±5.9 &
65.4±5.0 mm. The mean PT was 24.7 &
21.8 mm in males &
females respectively. The ML &
AP showed a statistically significant positive correlation with the height of the person (ML r=0.55; AP r=0.50 &
p=0.01). The tibial and femoral AR showed higher ratio for smaller knees &
smaller ratio for larger knees i.e. decline in AR for increasing AP dimension. None of the
Micromotion of the polyethylene (PE) inlay may contribute to backside PE wear in addition to articulate wear of total knee arthroplasty (TKA). Using radiostereometric analysis (RSA) with tantalum beads in the PE inlay, we evaluated PE micromotion and its relationship to PE wear. A total of 23 patients with a mean age of 83 years (77 to 91), were available from a RSA study on cemented TKA with Maxim tibial components (Zimmer Biomet). PE inlay migration, PE wear, tibial component migration, and the anatomical knee axis were evaluated on weightbearing stereoradiographs. PE inlay wear was measured as the deepest penetration of the femoral component into the PE inlay.Aims
Methods
One of the main causes of tibial revision surgery for total knee arthroplasty is aseptic loosening. Therefore, stable fixation between the tibial component and the cement, and between the tibial component and the bone, is essential. A factor that could influence the implant stability is the implant design, with its different variations. In an existing implant system, the tibial component was modified by adding cement pockets. The aim of this experimental in vitro study was to investigate whether additional cement pockets on the underside of the tibial component could improve implant stability. The relative motion between implant and bone, the maximum pull-out force, the tibial cement mantle, and a possible path from the bone marrow to the metal-cement interface were determined. A tibial component with (group S: Attune S+) and without (group A: Attune) additional cement pockets was implanted in 15 fresh-frozen human leg pairs. The relative motion was determined under dynamic loading (extension-flexion 20° to 50°, load-level 1,200 to 2,100 N) with subsequent determination of the maximum pull-out force. In addition, the cement mantle was analyzed radiologically for possible defects, the tibia base cement adhesion, and preoperative bone mineral density (BMD).Aims
Methods
The June 2024 Knee Roundup360 looks at: The estimated lifetime risk of revision after primary knee arthroplasty influenced by age, sex, and indication; Should high-risk patients seek out care from high-volume surgeons?; Stability and fracture rates in medial unicondylar knee arthroplasties; Rethinking antibiotic prophylaxis for dental procedures post-arthroplasty; Evaluating DAIR: a viable alternative for acute periprosthetic joint infection; The characteristics and predictors of mortality in periprosthetic fractures around the knee; Patient health-related quality of life deteriorates significantly while waiting six to 12 months for total hip or knee arthroplasty; The importance of looking for diversity in knee implants.
Total Elbow Arthroplasty (TEA) is a procedure to treat a number of conditions including rheumatoid arthritis (RA), post-traumatic arthritis, and osteoarthritis. To date, there has been minimal literature published on the Latitude since its release in 2001. There is one study reporting outcomes from the Latitude, a German study published in 2010. The purpose of this study was to analyse outcomes from primary Latitude TEAs. We performed a retrospective case series of 23 TEAs performed on 20 patients. 6 patients required revision surgery and were not included in the analysis. One patient was lost to follow up, resulting in 17 patients included for ROM analysis. All patients received Latitude TEA through a posterior approach and underwent a standard rehab protocol. 11 Patients were recalled at least two years post-op and were administered DASH and MAYO questionnaires. Complications such as triceps insufficiency, ulnar nerve dysfunction, infection, and aseptic loosening were recorded. Outcomes were compared using the Wilcoxon Signed-Rank test in STATA. Immediate post-op radiographs and patients most recent radiographs were analysed by a blinded upper-extremity surgeon not involved in the initial operation and analysed for loosening and implant malpostioning. Mean follow up was 4.8 years (range 2.6–7.5 years). Analysis of 17 TEAs in 16 patients revealed no difference in pre-operative ROM and post-operative ROM for flexion (121°±20 vs 129°±16, p=0.13) extension (40°±27 vs 27°±15, p=0.19), pronation (73°±13 vs 75°±24, p=0.55) or supination (64°±22 vs 68°±14, p=0.52). Patients who underwent TEA for RA had a significant improvement in flexion (121°±15 vs 135°±10, p<0.02). There was a statistically significant improvement in flexion-extension arc post-operatively (101°±28) compared to pre-operative scores (83±23 degrees, p<0.02). DASH and MAYO scores were calculated from 11elbows in 11 non-revision patients able to return for examination. The average MAYO score was 87.9 with nine patients in the “excellent” category, two patients in the “good” category, one patient in the “fair” category, and one in the “poor” category. The average DASH score was 32.9. Two patients underwent revision for periprosthetic fractures, two patients underwent revision for infection, one underwent revision for aseptic loosening and two for radial head dissociation (rate of 30%). This is one of the first studies examining the outcomes of the Latitude TEA. This retrospective case series demonstrates that the Latitude TEA has promising outcomes with respect to improving patient pain and functioning as assessed by the MAYO. Treatment using the Latitude TEA results in favorable functional outcomes for a majority of patients and offers an improvement in flexion-extension arc. Furthermore, our results are comparable to the MAYO scores reported by other studies analysing different
During total knee replacement (TKR), knee surgical navigation systems (KSNS) report in real time relative motion data between the tibia and the femur from the patient under anaesthesia, in order to identify best possible locations for the corresponding prosthesis components. These systems are meant to support the surgeon for achieving the best possible replication of natural knee motion, compatible with the prosthesis design and the joint status, in the hope that this kinematics under passive condition will be then the same during the daily living activities of the patient. Particularly, by means of KSNS, knee kinematics is tracked in the original arthritic joint at the beginning of the operation, intra-operatively after adjustments of bone cuts and trial components implantation, and after final components implantation and cementation. Rarely the extent to which the kinematics in the latter condition is then replicated during activity is analysed. As for the assessment of the active motion performance, the most accurate technique for the in-vivo measurements of replaced joint kinematics is three-dimensional video-fluoroscopy. This allows joint motion tracking under typical movements and loads of daily living. The general aim of this study is assessing the capability of the current KSNS to predict replaced joint motion after TKR. Particularly, the specific objective is to compare, for a number of patients implanted with two different TKR
Introduction:. Due to improvement in overall
Introduction: Acetabular loosening can limit long-term success of total hip replacement. There are at least 62 different
Introduction: Dislocation following total knee arthroplasty (TKA) is an unusual but dramatic post-operative complication. Previously reports involve only a few isolated cases. This study retrospectively analyzed the incidence, associated factors and treatment of dislocation following TKA. Method: All cases of TKA dislocation since 1970, when the first TKA was done at our institution, were identified from our institutional total joint registry (31.000 TKA). The medical history and X-ray were reviewed on all cases with this diagnosis. The 58 cases identified were reviewed with particular attention to associated factors that might contribute to this problem. Results: The overall incidence of TKA dislocation was 1.87 per 1.000 arthroplasties, with a rate of 0.93 and 6.61 for primary and revision TKA respectively. The dislocations occurred at the mean of 29.5 months (range 0 to 193). Original
Purpose: Aseptic loosening is one of the leading causes of failure in total elbow arthroplasty. It is logical to postulate that incorrect implant positioning and alignment may lead to excessive loading and wear which can induce the loosening cascade. However, the effect of implant malalignment on wear inducing loads in the elbow is not yet known. This in-vitro study determined the effect of anterior malpositioning, and varus-valgus (VV) and internal-external (IE) malrotations on humeral stem loading in total elbow arthroplasty. Method: The humeral, ulnar, and radial components of a linked total elbow arthroplasty were optimally positioned using computer navigation in eight cadaveric elbows, mounted in a load/motion control elbow simulator (age 75yrs, range 42–93; 5 male). A modular, humeral component was employed to generate implant malpositioning errors of ±6° VV, ±8° IE, and 5mm anterior. The implant was instrumented with strain gauges to quantify VV and IE bending loads during elbow flexion with the forearm in supination. Load output was combined using a sum-of-squares technique. Passive flexion was performed with the arm in the varus and valgus orientations; passive and active flexion were performed with the arm in the vertical orientation. Results: With the arm (humerus) in the vertical orientation, bending loads increased between 418Nmm and 1618Nmm for all malaligned implant positions (p<
0.05). Passive flexion (1354±859Nmm) produced higher resultant loads for the optimally positioned implant than active (819±891Nmm) flexion (p<
0.05). Although it varied during flexion, loading with the arm in varus (2928±1273Nmm) or valgus (2494±743Nmm) orientations resulted in up to a three-fold increase in loading when compared to the vertical orientation (p<
0.01). Conclusion: These data demonstrate that humeral component malpositioning increases loading in the implant, however further studies are required to determine the long term effect on polyethylene wear and component loosening.
Objective: Decreased quadriceps strength may contribute to anterior knee pain after total knee arthroplasty (TKA). The quadriceps force necessary to establish full extension is strongly dependent on the position and the relative length of the lever arms over the knee joint. The purpose of this in vitro study was to investigate the amount of quadriceps force required to extend the knee isokinetically after TKA in dependence of different
Introduction: There is an increasing interest in surface replacement arthroplasty (SRA) as an alternative to conventional THA (cTHA) in young and active patients. However, there has been considerable variability in reported outcomes. National joint registry reports have shown increased revision rates compared to cTHA. We analysed outcome measured as non-septic revision rate within two years for SRA in the NARA data base (Nordic Arthroplasty Register Association). Materials and Methods: 1638 SRA and 163802 cTHA with age up to 73 years and a non-fracture diagnosis, operated from 1995 to 2007, were compared using Cox multiple regression including age, gender, diagnosis, nation and prosthesis type with cTHA divided into cemented, uncemented, hybrid and reversed hybrid fixation. Men below 50 years of age (460 SRA and 7185 cTHA) were analysed as a subset. The SRA cohort with a mean follow-up 1,8 years was also analysed with the same method including age, gender, diagnosis, number of performed SRA per hospital and the four most commonly used
Aseptic loosening of the total TMC joint prosthesis occurs frequently and may depend on the design of the prosthesis. Numerous TMC
Introduction. It is well known that total knee arthroplasty (TKA) does not preserve normal knee kinematics. This outcome has been attributed to alteration of soft-tissue balance and differences between the geometry of the implant design and the normal articular surfaces. Bicompartmental knee arthroplasty (BKA) has been developed to replace the medial and anterior compartments, while preserving the lateral compartment, the anterior cruciate ligament (ACL), and the posterior cruciate ligament (PCL). In a previous study, we reported that unicompartmental knee arthroplasty did not significantly change knee kinematics and attributed that finding to a combination of preservation of soft-tissue balance and minimal alteration of joint articular geometry (Patil, JBJS, 2007). In the present study, we analyzed the effect of replacing trochlear surface in addition to the medial compartment by implanting cadaver knees with a bicompartmental arthroplasty design. Our hypothesis was that kinematics after BCKA will more closely replicate normal kinematics than kinematics after TKA. Methods. Eight human cadaveric knees underwent kinematic analysis with a surgical navigation system. Each knee was evaluated in its normal intact state, then after BKA with the Deuce design (Smith & Nephew, Memphis, TN), then after ACL sacrifice, and finally after implanting a PCL-retaining TKA (Legion, Smith & Nephew). Knees were tested on the Oxford knee rig, which simulates a quadriceps-driven dynamic deep knee bend. Tibiofemoral rollback and rotation and patellofemoral shift and tilt were recorded for each condition and compared using repeated measures ANOVA for significance. Results. Statistically significant differences were noted in femoral rollback between TKA and Intact conditions but not between Intact and BKA or between Intact and BKA without ACL. Statistically significant differences were noted in tibiofemoral rotation between TKA and Intact conditions but not between Intact and BKA or between Intact and BKA without ACL. No significant differences in patellar lateral shift or lateral tilt were found among the four conditions tested. Discussion & Conclusion. BKA prostheses that preserve the ACL and PCL allow for more normal knee kinematics than does conventional TKA. Our results supported our primary hypothesis that a bicompartmental approach would not significantly alter knee kinematics. These results also imply that replacement of the medial compartment and trochlear surface are not major factors contributing to altered knee function. The results that we observed may not necessarily apply to other BKA designs and should therefore not be extrapolated beyond the
Summary Statement. Femorotibial constraint is a key property of a total knee arthroplasty (TKA) prosthesis and should reflect the intended function of the device. With a validated simulation methodology, this study evaluated the constraint of two TKA prostheses designed for different intentions. Introduction. TKA prostheses are semi-constrained artificial joints. Femorotibial constraint level is a major property of a prosthesis and should be designed to match the device's intended function. Cruciate Retaining (CR) prostheses are usually indicated for patients with a functioning posterior cruciate ligament (PCL). For patients without a fully functioning PCL, CR-Constrained (CRC) prostheses with additional built-in constraint may be indicated. A CRC prosthesis usually consists of a CR femoral component and a tibial insert which has a more conforming sagittal profile to offer an increased femorotibial constraint. This study evaluated the anterior-posterior (AP) constraint behavior of two lines of prostheses (CR and CRC) from a same TKA product family. Using a validated computer simulation approach, multiple sizes of each product line were evaluated. Methods. Both the CR and CRC prostheses are from the same TKA product family (Optetrak Logic, Exactech, FL, USA) and share identical femoral components and tibial baseplates. The CRC tibial inserts have a more conforming sagittal profile than the CR tibial inserts, especially in the anterior aspect. Three sizes (sizes 1, 3, and 5) from each product line were included in this study. Computer simulations using finite element analysis (FEA) were performed to evaluate the femorotibial constraint of each prosthesis per ASTM F1223 standard [1]. The simulation has been validated by comparison with physical testing (more details submitted in a separate paper to CORS 2013). Briefly, FEA models were created using 10-node tetrahedral elements with all materials considered linear elastic. The tibial baseplate was distally fixed and a constant compressive force (710 N) was applied to the femoral component. Nonlinear Surface-Surface-Contact was established at the articulating surfaces, as well as between the tibial insert and the tibial baseplate. A coefficient of friction of 0.1 was assumed for all articulations [2]. The femoral component was driven under a displacement-controlled scheme to slide along AP direction on the tibial insert. Constraint force occurring at the articulation was derived from the reaction force at the distal fixation; thus, the force-displacement curve can be plotted to characterise the constraint behavior of the prosthesis. A nonlinear FEA solver (NX Nastran SOL601, Siemens, TX, USA) was used to solve the simulations. Results. The force-displacement curves predicted by the simulation exhibited the hysteresis loop appearance for both CR and CRC prostheses. The profile of the curves was generally consistent across different sizes for both product lines. The anterior constraint of the CRC prosthesis was significantly greater than the CR prosthesis. The posterior constraint of the CRC prosthesis was also slightly greater. Larger sizes exhibited reduced constraint compared to smaller sizes. Discussion/Conclusion. The increased constraint of the CRC prosthesis revealed in the study is consistent with the geometrical characteristics and the functional intent of the device. The CRC tibial insert is expected to provide significantly greater anterior constraint than the CR prosthesis to prevent paradoxical femoral translation when the patient's PCL is not fully functioning. The CRC tibial insert is also expected to provide slightly increased posterior constraint due to its elevated posterior lip. The observed hysteresis loop appearance is consistent with physical testing and the existence of friction. The reduced constraint on larger sizes is functionally desirable to offer proportional translation freedom. This study demonstrated the effectiveness of the simulation approach in quantifying the constraint behavior of different TKA