Better clinical outcomes and overall higher survival with hybrid versus cemented primary total knee arthroplasty: a minimum 15 years follow-up.

PURPOSE: To compare the clinical outcomes and survival at long-term between hybrid and cemented primary total knee arthroplasty (TKA). A better clinical outcome and survival following a follow-up as long as 15 years with the use of hybrid fixation as compared with cemented fixation was hypothesized. METHODS: Case-control study of 126 patients with a mean age of 62.4 years who underwent hybrid TKA matched with 126 patients underwent cemented TKA. Clinical outcome was assessed by the Knee Society scores (KSS) and reduced Western Ontario and MacMaster Universities questionnaire (WOMAC). Radiological assessment was made by the Knee Society method. RESULTS: The mean follow-up was 15.7 (range 15-17) years. At the final follow-up, clinical scores were significantly better in the hybrid group, although the differences were not clinically relevant. Revisions for all reasons were performed in five knees in the hybrid group and 15 knees in the cemented group (p = 0.033). In the hybrid group, there was one aseptic femoral loosening and no aseptic tibial loosening. In the cemented group, the main reasons for aseptic revisions were polyethylene wear (six knees) and tibial loosening (four knees). Cemented fixation was a significant risk factor for aseptic revision (hazard ratio 2.3; 95% CI 1.3-3.7%; p = 0.004). Survival at 15 years for aseptic reasons was 96.5% (95% CI 93.4-98.7%) in hybrid groups and 90.3% (95% CI 88.7-93.9%) in cemented group (p = 0.020). CONCLUSION: After a minimum follow-up of 15 years, hybrid fixation of primary TKA for osteoarthritis provide significantly higher clinical benefits compared with cemented fixation, but the differences were not clinically relevant. Hybrid fixation provides longer overall survival, although the femoral component survival was similar between groups. LEVEL OF EVIDENCE: III.

Evidence-Based Medicine (EBM) is properly perceived but its application is still limited in the orthopedic clinical practice: an online survey among the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) members.

PURPOSE: To evaluate the knowledge and awareness of Evidence-Based Medicine (EBM) among members of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA). METHODS: A questionnaire was developed that explored the following areas: (i) respondents' attitudes to EBM; (ii) their motivation to implement EBM in daily practice; (iii) their educational background, knowledge and skills related to accessing and interpreting information; (iv) their level of attention to, and use of, scientific literature; (v) access to and availability of evidence; (vi) perceived barriers in using EBM in clinical practice. The resulting data were analyzed using descriptive statistics, and the correlation between age, educational background and country was further investigated. RESULTS: Two-hundred and eighty-eight ESSKA members (11% of the total population) compiled the questionnaire. The participants covered all the five continents and an expected prevalence of European professionals (77%) was observed. The vast majority of participants were medical doctors (91%), mainly specialized in knee surgery with minimal involvement in research. 97% of the participants declared having some knowledge of EBM, acquired mainly during their professional education, with some geographical differences. The youngest clinicians and those from Eastern Europe reported the greatest difficulty in using EBM in daily practice. The application of EBM in clinical practice is positively affected by the time dedicated to research and negatively correlates with the time dedicated to patient care. CONCLUSIONS: The results of this survey highlight the need for further investigation into the main reasons behind the limited diffusion of the EBM approach, despite the medical community's knowledge and interest in the concept. A wider application of EMB would upgrade clinical practice, linking medical knowledge and scientific evidence to patients' needs which would result of benefit to patients, but also more in general to the health system.

Tourniquet application does not affect the periprosthetic bone cement penetration in total knee arthroplasty.

PURPOSE: Poor scientific evidence exists on the issue of tourniquet application during total knee arthroplasty (TKA). It has been suggested that tourniquet application might improve interdigitation of the cement into the periprosthetic bones due to relatively dry surgical field. The hypothesis of the present study was that tourniquet use did not affect the periprosthetic bone cement penetration. METHODS: The single-centre, randomized, controlled trial included 86 patients undergoing primary TKA (Clinical-Trials.gov NCT02475603). All patients meeting the inclusion criteria were randomly assigned to the tourniquet (n = 43) or non-tourniquet (n = 43) group after obtaining a written informed consent. The cumulative bone cement penetration was radiologically measured in AP (seven zones) and lateral views (three zones) as defined by Knee Society Scoring System. Further parameters such as perioperative blood loss, soft tissue swelling, pain level/analgesic consumption, operative time, length of hospital stay (LOS) and complication rate were statistically compared between the groups. RESULTS: The cumulative bone cement penetration averaged 28.5 ± 1.7 mm in tourniquet versus 26.6 ± 1.6 mm in non-tourniquet groups (n.s.). The mean intraoperative blood loss was 250 ml higher in the non-tourniquet group (p = 0.0001). Patient-reported pre- to 6th-day post-operative reduction of the pain level was significantly higher in the non-tourniquet group (p = 0.003). The Morphine Equivalent Dose was higher in the Tourniquet group at discharge day (p = 0.02). Parameters such as total blood loss, soft tissue swelling, surgical time, LOS, and complication rates revealed similar results between the groups. CONCLUSIONS: Tourniquet application did not influence the bone cement penetration significantly. Even though the intraoperative blood loss was reduced, the total blood loss was not affected significantly by tourniquet use. There was a tendency of higher post-operative pain and opioid analgesic requirement in the tourniquet group. LEVEL OF EVIDENCE: I.

Total Knee Arthroplasty Kinematics.

Knee kinematics is an analysis of motion pattern that is utilized to assess a comparative, biomechanical performance of healthy nonimplanted knees, injured nonimplanted knees, and various prosthetic knee designs. Unfortunately, a consensus between implanted knee kinematics and outcomes has not been reached. One might hypothesize that the kinematic variances between the nonimplanted and implanted knee might play a role in patient dissatisfaction following TKA. There is a wide range of TKA designs available today. With such variety, it is important for surgeons and engineers to understand the various geometries and kinematic profiles of available prostheses. The purpose of this review is to provide readers with the pertinent information related to TKA kinematics.

Ignore the Patella in Revision Total Knee Surgery: A Minimum 5-Year Follow-Up With Patella Component Retention.

BACKGROUND: In the setting of aseptic revision, a common question is: what should be done with the previously resurfaced patella? We report on a series of aseptic revision total knee arthroplasties (RTKA) where one or both components were revised and the patella was not. METHODS: The study group was 147 consecutive RTKA in 137 patients with a mean age of 70.1 ± 9.3 years where the patella was not revised. The average body mass index was 31.0 ± 5.4 kg/m2. Follow-up was a minimum of 5 years (range, 5 to 12 years). At final follow-up, 13 patients died and 2 patients were lost to follow-up leaving 122 patients and 130 knees available for review. Mean time from primary surgery to RTKA was 9.2 ± 5.5 years. Both components were revised in 50 knees, the femur only in 11 knees, the tibia only in 12 knees, and 57 had an isolated polyethylene revision. We found 5 patients with a mismatch between the patella and femoral components and 30 cases with patella component wear identified intraoperatively. RESULTS: At final follow-up, there were no reoperations on any patella and none were at risk of failure. There were 6 knees with a lateral patella tilt beyond 10°, but none were subluxed. Knee Society Scores averaged 85 ± 17.2 points at final follow-up. CONCLUSION: At midterm follow-up in this group of RTKA where the patella was not revised, we identified no subsequent failures of the patella. This is despite the presence of mild patella polyethylene wear and mismatched shapes in several knees. LEVEL OF EVIDENCE: III.

Comparison of Anterior-Stabilized and Posterior-Stabilized Total Knee Arthroplasty in the Same Patients: A Prospective Randomized Study.

BACKGROUND: A highly conforming, anterior-stabilized (AS) insert is designed to provide anteroposterior (AP) stability of the posterior-stabilized (PS) insert without a post. The purpose of this study was to compare the static and dynamic stability and function of AS and PS total knee arthroplasty (TKA) in the same patients. METHODS: A prospective, randomized controlled trial was performed in 45 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to receive an AS TKA, and the other knee was scheduled for a PS TKA from the same knee system. At 2 years postoperatively, the static AP stability was compared using anterior and posterior drawer stress radiographs at 90° knee flexion. Dynamic AP stability was evaluated using one-leg standing lateral fluoroscopic images throughout the range of motion. Knee function was compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. RESULTS: At 2 years postoperatively, there was a significant difference in knee AP laxity at 90° of flexion between the two groups (7.6 ± 3.9 mm in the AS group vs 2.2 ± 2.3 in the PS group, P < .001). However, there were no differences in dynamic AP stability under one-leg standing fluoroscopic lateral images at 30°, 60°, and 90° knee flexion (P = .732, P = .764, and P = .679, respectively). The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were not significantly different between the two groups (P = .641 and P = .582, respectively). CONCLUSION: Despite the fact that the AS TKA group showed significantly more static posterior displacement than the PS TKA group at 90° of knee flexion, both the AS and PS TKA groups showed similar dynamic stability under weight-bearing conditions and knee function at 2 years postoperatively.

Current Practice Trends in Primary Hip and Knee Arthroplasties Among Members of the American Association of Hip and Knee Surgeons: A Long-Term Update.

At the 2018 Annual Meeting of the American Association of Hip and Knee Surgeons, an audience response poll was conducted to determine current practice patterns among its members. The poll pertained to primary total hip arthroplasties and primary total knee arthroplasties, and results were compared to the findings from similar polls completed at previous annual meetings of the American Association of Hip and Knee Surgeons. This article summarizes the current findings and compares trends over time from the previous polls.

Satisfactory Short-Term Results of Navigation-Assisted Gap-Balancing Total Knee Arthroplasty Using Ultracongruent Insert.

BACKGROUND: The use of highly conforming ultracongruent (UC) polyethylene insert is bone-preserving and became a relatively common alternative to the conventional posterior stabilized total knee arthroplasty (TKA) design. The purpose of this study was to analyze the short-term clinical and radiologic results of UC insert TKA using the navigation-assisted gap-balancing technique. METHODS: Two hundred thirty-three knees were operated with a mean follow-up period of 8.1 years (minimum of 5 years). Radiologic and clinical outcomes were assessed before operation and at latest follow-up using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. For statistical analysis, paired sample t-test and analysis of variance were used. Significance was considered as P < .05. RESULTS: According to the preoperative deformities (valgus, mild varus, and moderate varus), there were 23 cases (9.9%) of valgus deformity, 180 cases (77.3%) of mild varus deformity, and 30 cases (12.9%) of moderate varus deformity. Overall, the results at mean 8.1 years revealed an improvement in mean Knee Society Score (54 ± 12 to 92 ± 3) and mean Western Ontario and McMaster Universities Osteoarthritis Index scores (62 ± 14 to 17 ± 3). Overall, 220 of 233 cases (94.4%) were in neutral alignment (between -3° and +3°) at latest follow-up. There were no migrating or shifting prosthesis that should be considered as possible failure. There was 0% component revision rate. CONCLUSION: Navigation-assisted gap-balancing technique using UC insert TKA had satisfactory short-term outcome. Strict gap-balancing technique using the offset-type-force-controlled-spreader-system aided in the satisfactory results.

Medial Mobile-Bearing Unicompartmental Knee Arthroplasty in Young Patients Aged Less Than or Equal to 50 Years.

BACKGROUND: Contemporary research has shown medial mobile-bearing unicompartmental knee arthroplasty to be an effective treatment in patients younger than 60 years; however, only one other study has specifically investigated unicompartmental arthroplasty outcomes in patients 50 years or younger. The purpose of this study was to determine the clinical outcomes and survivorship of medial mobile-bearing unicompartmental arthroplasty in this younger patient population. METHODS: A retrospective review of patients undergoing primary unicompartmental knee arthroplasty using the Oxford partial knee from 2003 to 2014 in a single practice database was performed. Patients were included in the study if they were 50 years of age or younger with a primary diagnosis of anteromedial osteoarthritis and minimum clinical follow-up of 2 years. Patient clinical outcomes, function, and need for revision surgery were assessed. RESULTS: The study included 340 knees. Average patient age was 46.5 years, and the mean follow-up was 6.1 years. Patients demonstrated significant improvements (P < .05) in range of motion (114.5 v 116.9), University of California Los Angeles activity score (4.4 vs 5.6), Knee Society clinical (37.3 vs 86.5) and functional scores (58.8 v 79.8). Overall, 20 patients required reoperation, and the predicted survival rate was 96% at 6 years and 86% at 10 years. Aseptic loosening occurred in 7 patients at an average of 5.6 years postoperatively, while 4 patients required conversion to total knee arthroplasty because of arthritic progression at a mean time of 6.6 years. There were no revision procedures required due to polyethylene liner wear or breakage. CONCLUSION: Medial mobile-bearing unicompartmental arthroplasty should be considered as a treatment option in patients younger than 50 years of age suffering from anteromedial osteoarthritis of the knee.

Computed Tomography Techniques Help Understand Wear Patterns in Retrieved Total Knee Arthroplasty.

BACKGROUND: Suboptimal total knee arthroplasty (TKA) position of both femoral and tibial components is thought to be linked with poor clinical outcomes, polyethylene wear and the "unexplained" painful knee arthroplasty. The aim of this study was to better understand the effect of implant orientation on knee implant performance. METHODS: We analyzed 30 retrieved contemporary TKA implants. Implant positioning measurements in the coronal plane were made prior to revision using a diagnostic algorithm, based on 3D computed tomography (CT) images. Each retrieved polyethylene component was imaged using a micro-CT scanner and a high resolution computational 3D model of each component was digitally reconstructed. The difference in thickness between medial and lateral components was calculated. Statistical analysis was performed to investigate the association between component positioning and damage patterns. RESULTS: We found a significant correlation between both the tibiofemoral and femoral angles and difference in thickness between polyethylene compartments: varus angulations were strongly associated with thinner medial compartments, whilst valgus angulations were associated with thinner lateral compartments. Moreover, suboptimal tibiofemoral orientations and tibial component angulations were associated to greater differences in thickness between polyethylene compartments. CONCLUSION: Our study is the first to compare accurate 3D CT measurements of prerevision TKA positioning in the coronal plane with postrevision retrieval analysis from innovative, accurate and highly reliable micro-CT-based method. Our results demonstrate the impact of component positioning on polyethylene damage and helps understanding of the in vivo performance of these implants. LEVEL OF EVIDENCE: III.

Disclosing Agents for the Intraoperative Identification of Biofilms on Orthopedic Implants.

BACKGROUND: Disclosing agents are dyes used in dentistry to colorize plaque (biofilm) and may offer a means for intraoperative detection of biofilms on orthopedic implants. Methylene blue (MB) stains biofilm and is safely used in orthopedic applications. Injection of MB into acutely infected prosthetic knees before debridement may enable visualization of biofilm, which could influence treatment decisions. The aims of this study were to determine if MB could be used to visualize biofilm on total knee arthroplasty (TKA) implants and to determine if MB staining has an antimicrobial effect that might interfere with subsequent culture. METHODS: Staphylococcus epidermidis biofilms were formed on TKA polyethylene liners and polymethylmethacrylate (PMMA) and Teflon discs. After staining biofilms on these implants, the bacterial densities were determined through sonication and quantitative culture. The antimicrobial activity of MB staining was determined by measuring the bacterial density of S. epidermidis biofilms on PMMA discs incubated in 0.05% MB for 24 hours vs 30 seconds and comparing it with controls unexposed to MB. RESULTS: MB stained S. epidermidis biofilms grown on TKA implants and Teflon and PMMA discs in vitro. Sonication and quantitative culture of the stained implants showed that bacterial densities were at supraphysiological levels. Staining did not affect the ability to culture the organism. CONCLUSION: MB is a possible cost-effective and novel method to expeditiously identify intraoperative biofilm. To further evaluate MB staining and its potential clinical usefulness, future studies are needed to assess the ability of MB to stain physiological levels of biofilm.

Correcting Severe Varus Deformity Using Trial Components During Total Knee Arthroplasty.

BACKGROUND: Extensive medial soft tissue release may be necessary to correct severe varus deformity during total knee arthroplasty (TKA). However, this procedure may result in instability. Here, we describe a novel soft tissue balancing technique, which can minimize medial release in severe varus deformity during TKA. METHODS: Fifty knees (40 patients) with hip-knee-ankle angle of more than 20° of varus were corrected using this technique (group 1). After achieving flexion gap balancing by needle puncturing and spreading of the superficial medial collateral ligament, extension gap balancing was obtained by gradual extension with the trial components in place. After group 1 was set, a one-to-one patient-matched control group who had mild varus deformity was selected by propensity score matching (50 knees, 48 patients, group 2). At postoperative 1 year, mediolateral laxity was compared between the 2 groups using the stress radiographs. Clinical outcomes were also compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. RESULTS: There were no differences in mean medial and lateral laxities between groups 1 and 2 at 1 year after the operation (medial laxity: 2.3° ± 1.4° and 2.7° ± 1.3°, respectively, P = .310) (lateral laxity: 3.6° ± 1.7° and 3.2° ± 2.0°, respectively, P = .459). There were no significant differences in postoperative clinical scores and knee alignment. CONCLUSION: Our technique of obtaining extension gap balancing using trial components led to safe and effective balancing by avoiding unnecessary extensive release in severe varus deformity during TKA.

Influence of Medial Collateral Ligament Release for Internal Rotation of Tibia in Posterior-Stabilized Total Knee Arthroplasty: A Cadaveric Study.

BACKGROUND: Previous studies suggested that changes in kinematics in total knee arthroplasty (TKA) affected satisfaction level. The aim of this cadaveric study was to evaluate the effect of medial collateral ligament (MCL) release by multiple needle puncture on knee rotational kinematics in posterior-stabilized TKA. METHODS: Six fresh, frozen cadaveric knees were included in this study. All TKA procedures were performed with an image-free navigation system using a 10-mm polyethylene insert. Tibial internal rotation was assessed to evaluate intraoperative knee kinematics. Multiple needle puncturing was performed 5, 10, and 15 times for the hard portion of the MCL at 90° knee flexion. Kinematic analysis was performed after every 5 punctures. After performing 15 punctures, a 14-mm polyethylene insert was inserted, and kinematic analysis was performed. RESULTS: The tibial internal rotation angle at maximum knee flexion without multiple needle puncturing was significantly larger (9.42°) than that after 15 punctures (3°). Negative correlation (Pearson r = -0.715, P < .001) between tibial internal rotation angle at maximum knee flexion and frequency of puncture was observed. The tibial internal rotation angle with a 14-mm insert was significantly larger (7.25°) compared with the angle after 15 punctures. CONCLUSION: Tibial internal rotation during knee flexion was reduced by extensive MCL release using multiple needle puncturing and was recovered by increasing of medial tightness. From the point of view of knee kinematics, medial tightness should be allowed to maintain the internal rotation angle of the tibia during knee flexion which might lead to patient satisfaction.

Obesity Does Not Affect Outcomes in Hybrid Versus Cemented Total Knee Arthroplasty in Asians.

BACKGROUND: This study aims to evaluate patient reported and functional outcomes following hybrid versus cemented total knee arthroplasty (TKA) in patients, stratified by body mass index (BMI). METHODS: Registry data of patients undergoing primary TKA between January 2004 and January 2013 were collected. Baseline interviews were conducted preoperatively to assess sociodemographic characteristics, BMI, and knee arthritis severity, using the Knee Society Score which consists of the Knee Society Knee Score and the Knee Society Function Score (KSFS) and Oxford Knee Score (OKS). These scores were collected prospectively, preoperatively, and postoperatively up to 2 years. Two-year outcomes and 5-year revision rates were then compared between (1) hybrid and cemented TKA groups and (2) BMI subclasses within the hybrid and cemented TKA groups. RESULTS: Patients who underwent cemented TKA had marginally better flexion range, KSFS, and OKS at 2 years postoperatively. In the overweight category, flexion range, KSFS, and OKS were marginally lower for hybrid TKAs. There were no differences in outcomes between the 2 groups in Class I and II obesity. Within the cemented TKA group, there were no differences in the outcomes between BMI subclasses. There were significant differences in the KSFS (0.023) and OKS (0.030) between the BMI subclasses within the hybrid TKA group, with patients in Class II obesity faring the worst. There was no statistically significant difference in the revision rates. CONCLUSION: We conclude that obesity does not affect outcomes in hybrid versus cemented TKA.

Comparison of osteoconductivity and absorbability of beta-tricalcium phosphate and hydroxyapatite in clinical scenario of opening wedge high tibial osteotomy.

The purpose of this study was to compare the osteoconductivity, and absorbability of hydroxyapatite or beta-tricalcium phosphate in clinical scenario of opening wedge high tibial osteotomy Total 41 knees of 40 patients with follow up period of more than 1 year were enrolled. These patients were divided into two groups, Group I (22 knees, 21 patients) used hydroxyapatite and Group II (19 knees, 19 patients) used beta-tricalcium phosphate as a substitute in the opening gap. According to proven method, the osteoconductivity was assessed radiographically by the extent of new bone formation at osteotomy space and absorbability was evaluated by measuring the area occupied by substitute at immediate postoperative, postoperative 6 months and 1 year. Regarding preoperative demographic data, no significant differences were found between two groups. No statistically significant differences were found between two groups regarding lower limb alignment (mechanical femorotibial angle, weight-bearing line%) and posterior tibial slope at postoperative and final follow up radiographs. Concerning the osteoconductivity, there were no significant differences between two groups in any zone. However, the absorption rate was significantly greater in the Group II than in Group I at 6 months (Group I: 13.7 ± 6.8, group II: 35.3 ± 15.8, P = 0.001) and 1 year (Group I: 24.2 ± 6.3, Group II: 49.6 ± 14.3, P < 0.0001). The complications related to bone substitutes were not observed. Both hydroxyapatite and beta-tricalcium phosphate showed satisfactory gap healing without complications and can be successfully used as alternative healing materials in opening wedge high tibial osteotomy. Our study showed that beta-tricalcium phosphate has superior absorbability than hydroxyapatite. But osteoconductivity showed no significant difference.

Knee Arthroplasty After Subchondroplasty: Early Results, Complications, and Technical Challenges.

BACKGROUND: Calcium phosphate bone substitutes (CPBS) are commonly used to augment and repair bone voids and defects after fractures around the knee joint. The purpose of this study was to determine whether prior arthroscopic application of a CPBS, for repair of magnetic resonance imaging-identified subchondral fractures associated with osteoarthritis (procedure referred to as subchondroplasty) adversely affected the performance and/or outcome of subsequent knee arthroplasty. METHODS: Twenty-two patients who had arthroscopic repair of a periarticular fracture combined with use of a CPBS who later had knee arthroplasty were identified. Average follow-up for study patients was 23.5 months (range 12-52 months). These patients were matched demographically and for follow-up duration in a 2:1 ratio to a group of control subjects undergoing arthroplasty who had not undergone prior surgery. RESULTS: Technical challenges related to surgical performance, clinical outcomes, and complications were determined for both the groups. At most recent follow-up, study patients had an average Oxford score of 40.6 (range, 25-48) compared with control subjects with an average score of 40.1 (range, 12-48). There was no difference in complications or surgical complexity between groups, and only standard primary components were used. CONCLUSION: The results of our study suggest that prior arthroscopic repair combined with CPBS of periarticular fractures around the knee does not compromise the early outcomes and surgical performance or increase complications related to subsequent arthroplasty. However, longer follow-up of these patients is warranted to confirm that implant durability remains uncompromised.

Medial over-resection of the tibia in total knee arthroplasty for varus deformity using computer navigation.

We are reporting a series of 35 cases in which downsizing, lateralizing of the tibial baseplate and resection of the uncovered medial plateau bone releases the medial collateral ligament and tightens the lateral collateral ligament. Result in excellent ligamentous balance and correction to neutral mechanical axis. The mean follow up was 32.8 months (11-95 months) and the average pre-operative varus was 9.47° (3.5-15°) with the average post-operative alignment was 0.65° varus. We obtained a mean correction of 0.45° for every mm (millimeter) of bone resected. We did not have any varus collapse or instability. Medial Over-resection could be employed as a technique in the management of varus OA knee with 2mm of resection giving about 10 correction of deformity.

Doctor, what does my knee arthroplasty weigh?

The aim of this study was to compare the weight of the total knee arthroplasty (TKA) implants and the weight of the natural knee. A prospective study was conducted with two different brands of cemented primary TKA. During the procedure, we collected the removed bone, soft tissues and the post-implantation cement and weighed them all separately at the end. In both groups, the implants plus cement were significantly heavier than the removed bone and soft tissues. The average weight gained was 266.7 ± 35.1 g for group 1 and 279.1 ± 48.7 g for group 2. This significant local weight gained after TKA is a new parameter that should be taken into account for further studies and when creating new implants.

Improvement of rotational arc during deep flexion range of a novel designed polyethylene insert for posterior-stabilised total knee arthroplasty.

BACKGROUND: One of the remaining issues in total knee arthroplasty (TKA) is achieving sufficient rotational arc during deep flexion range of the knee for specific postures such as the 'seiza' or cross-legged sitting. This study aimed to evaluate whether there was a change in the actual in vivo rotational arc during deep flexion range before and after a design change of polyethylene (PE) inserts. METHODS: In 50 posterior-stabilised TKA cases, knee kinematics, including rotational movement, were measured intraoperatively using an image-free navigation system to compare a newly designed PE insert with reduced the posterior lip with a conventional PE insert. Femoral-tibial rotational angles at 30°, 45°, 60°, 90°, 120°, and 130° knee flexion were evaluated. Varus/valgus instability, knee range of motion, and femoral rollback were also measured. Obtained parameters were compared between new and conventional PE inserts. The independent factors associated with rotational arc during deep flexion range (120° and 130° knee flexion) were analysed using multivariate analysis. RESULTS: The newly designed PE insert demonstrated a significant increase in the rotational arc at 120° (22.9 ± 8.7° vs. 30.1 ± 11.9°, P < 0.001) and 130° (24.3 ± 9.5° vs. 32.5 ± 12.4°, P < 0.001) knee flexion compared with that with the conventionally designed posterior-stabilised insert. Multivariate analysis demonstrated that using the newly designed PE insert was an independent predictor of improved rotational arc during deep flexion range: regression coefficient was 11.2 (95% confidence interval 7.1-15.3, P < 0.001). CONCLUSION: The design change, which reduced the posterior lip of the PE insert, contributed to improved rotational arc in 120° and 130° deep flexion ranges.

Superior two-year results of externally unsupported polyester compared to supported grafts in above-knee bypass grafting: a multicenter randomised trial.

OBJECTIVES: The aim of this study was to compare externally supported thin wall knitted polyester (P-EXS) and externally unsupported thin wall knitted polyester (P-non-EXS) for above-knee (AK) femoro-popliteal bypass grafting. DESIGN: A prospective multicenter randomised clinical trial. MATERIAL AND METHODS: Between 1999 and 2008, 265 AK femoro-popliteal bypass grafts (6 mm in diameter) were performed, including 136 P-EXS and 129 P-non-EXS. The selection of patients was based on the presence of disabling claudication or critical ischaemia. Follow-up took place at 3, 6, 12, 18, and 24 months and included clinical examination and duplex ultrasonography. The main end points of this study were primary patency rates at one and two years. Secondary end points were mortality, and primary assisted and secondary patency rates. Cumulative patency rates were calculated with life-table analysis and log-rank testing. RESULTS: The 1-year primary, primary assisted and secondary patency rates were 65%, 70% and 84%, respectively, for P-EXS and 76% (p = 0.05), 82% (p = 0.03) and 88% (p = 0.35), respectively, for P-non-EXS. Two-year primary, primary assisted and secondary patency rates were 45%, 57% and 70%, respectively, for P-EXS and 62% (p = 0.003), 75% (p = 0.005) and 84% (p = 0.02), respectively, for P-non-EXS. The overall mortality rate after two years was 11.3%. CONCLUSION: In above-knee femoro-popliteal bypass grafting patency rates of externally supported knitted polyester grafts were inferior to their unsupported counterpart. ISRCTN: At the time this study started this number was not the standard.