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Background Total knee arthroplasty (TKA) is one of the most performed orthopedic procedures worldwide. While excellent efficacy has been reported, about 20% of patients are not satisfied with the result. A potential cause is the problematic reproduction of knee kinematics. This systematic review examines gait analysis studies in primary medial pivot (MP) and posterior stabilized (PS) TKAs to investigate the differences between the two prosthesis designs. Methods A systematic review was conducted by following PRISMA guidelines. Five databases (PubMed, Medline, Embase, Scopus and the Cochrane Database of Systematic Reviews) were analyzed, and eligible articles were evaluated in terms of the levels of evidence. The methodological quality of the articles was assessed by using the MINORS scoring. This review was registered in PROSPERO. Results Nine studies were included. Gait analysis was performed in 197 MP TKA and 192 PS TKA patients. PS TKA cases showed (P P P > 0.05) was reported regarding gait spatial–temporal parameters. The Forgotten Joint Score (FJS) and Western Ontario and McMaster Universities Comparison in terms of Arthritis Index (WOMAC) score (mean stiffness) showed that MP TKA yielded significantly better results than PS TKA. Conclusions This systematic review revealed significant kinematic and kinetic differences between MP and PS TKA at all gait analysis phases. Furthermore, the considerable difference between TKA design and the kinematics of healthy knee were highlighted in this study. Level of evidence III.

Postoperative instability represents one of the most common complications following primary total knee arthroplasty (TKA). To prevent this outcome, valgus deformities have been historically treated using more constrained implants. The purpose of this study was to evaluate the outcome of treating a moderate valgus deformity by combining a surgical technique used to release the postero-lateral soft tissue envelope with the use of a medially congruent (MC) TKA design without using classical, semi-constrained inserts. Seventy-nine MC TKAs were performed by three surgeons at three institutions between 2016 and 2018 as part of a multicenter, international study. Inclusion criteria were: radiographic late-stage osteoarthritic knees with Ranawat’s type 1 or 2 classification of valgus deformity and integrity of the medial capsular–ligament complex (less than 10 mm of medial opening during valgus stress test at 10° of knee flexion). Exclusion criteria were: BMI > 40; neuromuscular, metabolic, or immunologic disorders; or the inability to complete outcome measures or radiographic assessment. Seventy-seven patients (79 knees), 59 males and 18 females, were evaluated at 2-year minimum follow-up according to the Knee Society Score (KSS) and Forgotten Joint Score (FJS). Mean age at surgery was 70 years (range 48–91). The mean range of motion (ROM) improved from 110° (range 85°–130°) preoperatively to 121° (range 105°–135°) (p

Periprosthetic joint infections (PJIs) represent a devastating consequence of total joint arthroplasty. The European Knee Associates (EKA), the American Association of Hip and Knee Surgeons (AAHKS) International Committee, and the Arthroplasty Society in Asia (ASIA) board members were interested in quantifying differences in arthroplasty surgeons’ use of various PJI prevention measures to provide clinical recommendations to reduce PJI incidence. A prospective Microsoft Forms online survey was distributed among EKA, AAHKS International Committee, and ASIA members and their affiliated arthroplasty surgeons. The survey consisted of 20 single and multiple response questions focused on PJI prevention strategies at three perioperative periods: preoperatively, intraoperatively, and postoperatively. Three hundred and ninety-four arthroplasty surgeons from 6 different continents completed the survey. Preoperative: (A) PJI Risk Stratification: 40.6% routinely set thresholds (e.g., BMI, HgbA1C) to be met to qualify for surgery, 36.5% only review past medical history; 9.1% use machine learning to personalize PJI risk; (B) BMI limit: 36% no limit; 15.4% BMI

To evaluate the influence of short versus long stems implanted through a Direct Anterior Approach (DAA) on clinical and radiological outcomes in THA at medium-term follow-up (average follow-up of 44.8 months).167 consecutive total hip arthroplasties treating patients affected by primary hip osteoarthritis were retrospectively evaluated. A standard-length stem (H-MAXs) was used in 70 patients, while a short metaphyseal-fitting femoral stem (MINIMA) was used in 97 patients. The Harris Hip Score (HHS) and Forgotten Joint Score-12 (FJS) were used as outcomes measurements. Post-operatively, Engh's score and Brooker classification were analyzed at 6 months, 1 year and every 2 years until the final FU. The correct size of the implant was evaluated determining the canal fill index (CFI), and all undersized stems were classified according to Magra classification.The average HHS was 83 ± 13.4 in the standard stems group and 87 ± 14.1 for short stems group (p = 0.148). The average FJS was 87.9 ± 15.2 for patients in the standard stems group and 84.5 ± 17.7 with no significant differences (p = 0.327). None of the stems showed radiographic signs of instability (standard stems mean Engh's score: 19.25 versus short stems mean Engh's score: 19.50-p = 0.41). According to Brooker classification, no significant difference in severity was found using different stems (p = 0.715). A high rate of undersized stems was found (standard stems 24%-short stems 25%) but without statistical difference between groups (p = 0.078), while a different trend in malposition following the recent classification proposed by Magra et al. was observed evaluating all undersized stems (p = 0.0387).Both groups achieved good and comparable patient-reported outcome measurements (PROMs) and radiographic stability with fixation observed by bone ingrowth. A high rate of undersized stems was found with a correlation between femoral stem length and specific pattern of malposition. Malalignment in Varus was frequent in shorter stems in contact proximally with medial calcar and distally with lateral cortex, while a uniform undersizing was observed for longer ones with a continuous margin around the stem. However, the stems never presented progressive radiolucent lines over the whole surface of the stem.

Periprosthetic joint infections (PJI) represent one of the most catastrophic complications following total joint arthroplasty (TJA). The lack of standardized diagnostic tests and protocols for PJI is a challenge for arthroplasty surgeons. Next generation sequencing (NGS) is an innovative diagnostic tool that can sequence microbial deoxyribonucleic acids (DNA) from a synovial fluid sample: all DNA present in a specimen is sequenced in parallel, generating millions of reads. It has been shown to be extremely useful in a culture-negative PJI setting. Metagenomic NGS (mNGS) allows for universal pathogen detection, regardless of microbe type, in a 24–48-hour timeframe: in its nanopore-base variation, mNGS also allows for antimicrobial resistance characterization. Cell-free DNA (cfDNA) NGS, characterized by lack of the cell lysis step, has a fast run-time (hours) and, together with a high sensitivity and specificity in microorganism isolation, may provide information on the presence of antimicrobial resistance genes. Metagenomics and cfDNA testing have reduced the time needed to detect infecting bacteria and represent very promising technologies for fast PJI diagnosis. NGS technologies are revolutionary methods that could disrupt the diagnostic paradigm of PJI, but a comprehensive collection of clinical evidence is still needed before they become widely used diagnostic tools. Cite this article: EFORT Open Rev 2021;6:236-244. DOI: 10.1302/2058-5241.6.200099

In this article the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining a total hip arthroplasty (THA) undergoing acute periprosthetic joint infection (PJI). This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulphate antibiotic-added beads. The combination of 3 different surgical techniques (tumour-like synovectomy, Argon Beam application and chlorhexidine gluconate brushing) might enhance the disruption and removal of the bacterial biofilm which is the main responsible of antibiotics and antibodies resistance. The timing of the diagnosis (6 weeks from the original surgery or 1 week from clinical symptoms appearance in the case of an hematogenous infection) and the preoperative isolation of the germ are fundamental in order to obtain a satisfactory outcome. A 12-week course of postoperative antibiotic therapy (6 weeks I.V. and 6 weeks oral) complete the postoperative protocol used by the authors. The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous PJI.

Modern total knee arthroplasty (TKA) systems are designed to reproduce the normal knee kinematics and improve patient outcome. The authors compared two different third-generation medial pivot TKA implants, having a single-radius or a J-curve design in their sagittal plane, hypothesizing no clinical differences. Two cohorts of 50 patients who underwent primary TKA were first preoperatively matched by sex, deformity, body mass index (BMI), Oxford Knee Score (OKS), Knee society score (KSS) and range of motion (ROM) and then statistically analyzed at a minimum follow-up (FU) of 2 years. An identical surgical technique, which aimed to reproduce a slightly tighter medial than lateral compartment, was used in all knees. At a minimum follow-up of 2 years (range 24–34 months) there were no statistically significant differences in OKS and KSS between the two implant groups. The final ROM differed statistically between the two groups: the average maximum active flexion was 123° in the J-curve femoral design group with an adapted “medially-congruent” polyethylene insert, and 116° in the single radius femoral design with a medial “ball-in-socket” articulation. No clinical and radiological differences were found when the two cohorts of patients were compared. This study showed that the implant design played a minor role in the final outcome as opposed to a precise surgical technique. Retrospective case-control study, Level III.

BACKGROUND: Metal-on-Metal (MoM) total hip arthroplasty (THA) represents a very controversial procedure because of the possibility of postoperative adverse local tissue reaction (ALTR). This study investigates the reliability of the ultrasound scan as a diagnostic tool to quantify a clinically useful threshold in the level of periprosthetic fluid collection to suggest implant revision. METHODS: This study includes 116 patients (123 implants) who received an Articular Surface Replacement XL (ASRTMXL, De Puy Synthes, USA) MoM THA. The study group included 56 males and 60 females with a mean age of 66.6 years (range, 15–86 years). All patients were clinically and radiologically annually evaluated (according to the Harris Hip Score) up to a mean follow-up of 7.5 years (min. 1.4 – max. 10.3 years) from the primary surgery: all patients underwent standard ultrasound evaluation of the affected hip and Cobalt/Chromium blood detection testing according to a custom-made diagnostic algorithm for MoM THA revision. RESULTS: At final follow-up, 51 (43.1%) of 117 implants underwent revision after a mean of 6 years (1.79–9.26) from the primary ASR implant. The authors found a statistically significant correlation between Cr (p = 0.015) and Co (p = 0.009) blood values and different ultrasound grades. Statistical analysis showed a significant association between periprosthetic fluid collection and revision surgery (p

Background Osteochondral knee defects (OCD) are often symptomatic, causing pain and functional impairment even in young and active patients. Regenerative surgical options, aiming to stimulate natural cartilage healing, have been recently used as a first line treatment. In this study, a new hydrogel is investigated in its capacity to regenerate the ultra-structural quality of hyaline cartilage when combined with a classical microfracture technique. Material and methods Forty-six patients, affected by grade III and IV knee chondropathies, were consecutively treated between 2013 and 2015 with microfractures followed by application of a modern hydrogel in the lesion site. All patients underwent clinical evaluation (WOMAC) pre-operatively, at 6,12 and at 24 months postoperatively: the results were compared with a subsequent, consecutive, matched, control group of 23 patients treated with microfractures alone. In a parallel and separate in-vitro histological study, adipose derived mesenchymal stem cells (ADMSCs) were encapsulated in the hydrogel scaffold, induced to differentiation into chondrocytes, and observed for a 3 weeks period. Results The initial WOMAC score of 58.6 ± 11.0 in the study group was reduced by 88% at 6 months (7.1 ± 9.2) and 95% at 24 months (2.9 ± 5.9). The “in-vitro” study revealed a histological characterization typical of hyaline cartilage in study group. Separate biopsies performed at 12 months post-op in the study group also revealed type 2 collagen and hyaline-like cartilage in the regenerated tissue. Conclusion Our study demonstrated high patient satisfaction rates after microfractures combined with a modern hydrogel scaffold; histologic evaluation supported the hypothesis of creating an enhanced chondrogenic environment. Microfracture “augmentation” using modern acellular biomaterials, like hydrogels, might improve the clinical outcomes of this classical bone marrow stimulating procedure.

Background Our purpose was to evaluate the clinical and radiographic outcomes of proximal humeral fractures treated with a new generation plating system and compare results with a meta-analysis of recent literature. Methods Between 2014 and 2017, 93 patients (18 males, 75 females) with proximal humerus fractures were treated with open reduction and internal fixation (ORIF) using a Pantera® Plate. These low-profile plates are anatomically shaped and include “cross-elements” that form a three-dimensional scaffold in bone to enhance fixation stability. According to Neer classification, there were 24 two-part fractures, 49 three-part fractures and 20 four-part fractures (4 with dislocated heads). X-rays and Constant Shoulder Scores (CSS) were used to evaluate healing, complications, and clinical outcomes. Results were compared with a meta-analysis of similar studies reported in literature over the last 10 years. Results Eighty-three patients with a minimum follow-up of 2 years had a mean CSS of 72 (53–90) graded as excellent for 23 patients (28%), good for 35 (42%), fair for 14 (17%), and poor for 11 (13%). Fractures healed without complication in 75 (91%) patients. Eight (9%) complications were observed, i.e., three avascular necrosis of the humeral head, one case of implant loosening, two cases of subacromial impingement and two superficial infections. There was no significant correlation between Neer fracture stage and patient outcome (p = 0.257). Compared to the literature, this method had a lower complication grade (p = 0.03), though it did not significantly differ in its clinical outcomes (p = 0.08). Conclusions The investigated plating system includes design features that can potentially increase utility for ORIF of proximal humeral fractures. While the complication profile was signficantly less than reported in the literature for standard proximal humerus plates, clinical outcomes were similar. Further studies will be required to better understand the role of plate design on treatment of these challenging fractures. Level of evidence IV, therapeutic study.

Unicompartmental Knee Arthroplasty (UKA) is an effective surgical option for managing unicompartmental knee osteoarthritis; it represents 10% of all knee arthroplasties worldwide, increasing 32.5% annually in the United States alone. Despite evolution in surgical technique and implant design, success rate and long-term survivorship of UKA have been historically lower than Total Knee Arthroplasty (TKA). The most common causes of UKA failure leading to revision are polyethylene wear, progression of arthritis, aseptic loosening and patella-femoral symptoms due to poor patient selection in many cases. Historically, UKA revisions have presented technical challenges mainly related to managing residual bone defects and ligament insufficiency ultimately leading to knee instability: the fear of instability has often pushed surgeons to lower the threshold for an increase of the intra-articular level of constraint. Unfortunately, the use of more constrained implants requires sacrificing bone stock and has been related to higher rates of re-revision secondary to recurrence of aseptic loosening. Because of these challenges, the authors developed a surgical technique that could combine balancing the knee during revision surgery with the use of the less constrained polyethylene option. To achieve this, we started evaluating a novel device (VERASENSE, Orthosensor, FL) designed to support soft tissue balancing during primary TKA. This intraoperative sensing technology dynamically quantifies intra-articular loads during TKA trial with the goal of correcting any residual imbalance in real time. Herein we propose a novel surgical technique, which might allow use of a primary TKA design characterized by a lower level of constraint, instead of a constrained or hinged revision knee system, during UKA revision. A key aspect of this technique is the use of sensing technology during intraoperative stability testing.

Evidence is limited regarding cannabinoid use among total joint arthroplasty (TJA) patients, despite increased availability and popularity for treating chronic pain. The authors hypothesized that preoperative cannabinoid use increased and opioid use decreased during a 6-year interval in total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients, and also asked whether complications were associated with use of these substances. This retrospective, single-institution study reviewed electronic medical records and the Veterans Affairs Surgical Quality Improvement Program (VASQIP) database for TJA cases from 2012 through 2017. Primary outcomes were the prevalence and trends of active cannabinoid and opioid use, as determined by routine preoperative urine toxicology screening. Multivariable regression analyses were conducted to investigate a secondary outcome, whether there was an association between cannabinoid or opioid use and postoperative complications. A total of 1778 operations (1161 TKAs and 617 THAs) performed on 1519 patients were reviewed. The overall prevalence of pre-operative cannabinoid and opioid use was 11% and 23%, respectively. Comparing 2012 with 2017, cannabinoid use increased from 9% to 15% ( P =.049), and opioid use decreased from 24% to 17% ( P =.040). Cannabinoid users were more likely to be taking opioids than nonusers ( P =.002). Controlling for age, sex, surgery type, and American Society of Anesthesiologists score, cannabinoid use was not associated with 90-day readmission, infection, reoperation, or other VASQIP-captured complications. Laboratory testing indicated a much higher prevalence of cannabinoid use among TJA patients than previously reported. During a 6-year period, cannabinoid use increased more than 60%, and opioid use decreased approximately 30%. These findings indicate that cannabinoid use did not appear to be associated with perioperative complications. [ Orthopedics . 2021;44(1):e101–e106.]

Achieving a well-balanced total knee arthroplasty (TKA) is a difficult task, but the use of real-time sensing technology could provide intraoperative dynamic feedback regarding stability and load. This study compared intraoperative data and clinical outcomes between two cohorts, where one cohort had a sensor-guided medial pivot TKA performed.Methods:Two cohorts of 50 patients each were preoperatively matched to receive the same TKA, having a J-curve femoral design with an adapted “medially congruent” polyethylene insert; the second cohort (group B) underwent the intraoperative sensor-check. Intraoperative sensor data were recorded as tibiofemoral load at 10°, 45°, and 90°. We considered stable knees those with a pressure Results:All patients (group A: no sensor; group B: sensor) were available at 2-year minimum follow-up (FU; min. 24 months, max. 34 months); no preoperative statistical differences existed between groups in the average range of motion (ROM), OKS, KSS, and body mass index. There were no statistical differences at final FU between groups in the average OKS (group A: 41.1; group B: 41.5), in the average KSS (group A: 165.7; group B: 166.3), or in final ROM (group A: 123°; group B: 124°). One patient in each group required a manipulation under anesthesia. In the sensor group, an accessory soft tissue release/bone recut was necessary after sensor testing with trial components in 24% to obtain the desired loads; in the same group, the level of constraint in the final components was increased to posterior-stabilized in 12% because of an inter-compartmental difference >40 lbs. Surgical time was 8 min longer in the sensor group.Conclusion:The use of this sensing technology did not improve the clinical outcome but supported multiple intraoperative decisions aimed to better reproduce the medial pivot kinematic of the normal knee.

Purpose The Covid-19 pandemic has disrupted health care systems all over the world. Elective surgical procedures have been postponed and/or cancelled. Consensus is, therefore, required related to the factors that need to be in place before elective surgery, including hip and knee replacement surgery, which is restarted. Entirely new pathways and protocols need to be worked out. Methods A panel of experts from the European Hip Society and European Knee Association have agreed to a consensus statement on how to reintroduce elective arthroplasty surgery safely. The recommendations are based on the best available evidence and have been validated in a separate survey. Results The guidelines are based on five themes: modification and/or reorganisation of hospital wards. Restrictions on orthopaedic wards and in operation suite(s). Additional disinfection of the environment. The role of ultra-clean operation theatres. Personal protective equipment enhancement. Conclusion Apart from the following national and local guidance, protocols need to be put in place in the patient pathway for primary arthroplasty to allow for a safe return.

Purpose The COVID-19 pandemic has disrupted the health care system around the entire globe. A consensus is needed about resuming total hip and knee procedures. The European Hip Society (EHS) and the European Knee Association (EKA) formed a panel of experts that have produced a consensus statement on how the safe re-introduction of elective hip and knee arthroplasty should be undertaken. Methods A prospective online survey was done among members of EHS and EKA. The survey consisted of 27 questions. It includes basic information on demographics and details the participant’s agreement with each recommendation. The participant could choose among three options (agree, disagree, abstain). Recommendations focussed on pre-operative, peri-operative, and post-operative handling of patients and precautions. Results A total of 681 arthroplasty surgeons participated in the survey, with 479 fully completing the survey. The participants were from 44 countries and 6 continents. Apart from adhering to National and Local Guidelines, the recommendations concerned how to make elective arthroplasty safe for patients and staff. Conclusion The survey has shown good-to-excellent agreement of the participants with regards to the statements made in the recommendations for the safe return to elective arthroplasty following the first wave of the COVID-19 pandemic.

Total knee arthroplasty is a successful procedure in treating subjects with end-stage knee osteoarthritis. The objective of this matched study was to evaluate subjective patient satisfaction and clinical and radiological outcomes in two groups of patients undergoing primary TKA using an identical third-generation design with different conformity in the polyethylene insert. One hundred consecutive patients undergoing TKA because of knee osteoarthritis were randomized in two matched groups. Group A included 50 Posterior-Stabilized (PS) implants, while group B included 50 Medially Congruent (MC) implants. The surgical technique was identical: gap balancing in extension and measured resection in flexion; cruciate ligaments were always removed; the coronal alignment followed the mechanical axis and the tibial slope was set at 3° in the PS group and 5° in the MC. Oxford Knee Score (OKS) and Knee Society Score (KSS) were assessed preoperatively and at 2 year minimum follow-up. Two-sample T test statistical analysis was performed. All patients were available at final follow-up: there were no preoperative statistical differences between the two groups in the average preoperative ROM (PS 112°, MC 108°; n.s.), average preoperative KSS (PS 64.4, MC 63.7; n.s.), average preoperative OKS (PS 19.6; MC 19.0; n.s.), and average BMI (PS 34.40, MC 34.60; n.s.). At final follow-up, there were no statistical differences between the two groups in the average OKS (PS 40,5; MC 41.1; n.s.) and in the average KSS (PS 161,5, MC 165,7; n.s.). We found a statistically but not clinically significant difference at final ROM: the average maximum active flexion was 120° in the PS group and 123° in the MC group (s.s.). This study evaluated two biomechanically different polyethylene inserts in the same TKA design, showing that reducing the level of intra-articular conformity had minimal effects on PROMs and objective short-term clinical results but a potentially beneficial effect on ROM. This study suggests that, once a satisfactory intra-operative stability is obtained, the minimal level of constraint should be used. III.

Periprosthetic joint infection (PJI) is a serious complication in total knee arthroplasty (TKA) and represents one of the most common causes of revision. The challenge for surgeons treating an infected TKA is to quickly obtain an infection-free joint in order to re-implant, when possible, a new TKA. Recent literature confirms the role of local antibiotic-loaded beads as a strong bactericidal, allowing higher antibiotic elution when compared with antibiotic loaded spacers only. Unfortunately, classical Polymethylmethacrylate (PMMA) beads might allow bacteria adhesion, secondary development of antibiotic resistance and eventually surgical removal once antibiotics have eluted. This article describes a novel surgical technique using static, custom-made antibiotic loaded spacers augmented by calcium sulphate antibiotic-impregnated beads to improve the success rate of revision TKA in a setting of PJI. The use of calcium sulphate beads has several potential benefits, including a longer sustained local antibiotic release when compared with classical PMMA beads and, being resorbable, not requiring accessory surgical interventions.

Total knee arthroplasty is a traditional surgical procedure aimed to restore function and relief pain in patients with severe knee osteoarthritis. Recently, many medial pivot knee systems were deigned to replicate the normal knee kinematic: a highly congruent medial compartment and a less conforming lateral tibial plateau characterize these devices. A slightly asymmetric soft tissue balancing is mandatory using medial pivot designs to obtain a correct and physiological knee biomechanics leading good outcomes and long survival rates. This article describes a new surgical technique using a modern third generation TKA design combined with wireless load-sensor tibial trials to improve the correct knee load balancing with a minimal conformity of the polyethylene insert. The use of wireless load-sensing tibial trials has several benefits: it is an intraoperative, objective and dynamic tool allowing surgeons to optimize in real time soft tissue balancing. The meaning of a "truly balanced knee" is still a controversial issue in the current literature.

Multimodal analgesic clinical pathways for joint replacement patients often include perineural catheters, but long-term adherence to these pathways has not yet been investigated. Our primary aim was to determine adherence rate to a knee arthroplasty clinical pathway for patients undergoing staged bilateral procedures.This study was performed at a hospital with a Perioperative Surgical Home program and knee arthroplasty clinical pathway using multimodal analgesia and adductor canal catheters. Data were examined for all orthopedic surgery patients over a 4-year period. We included patients who had staged bilateral knee arthroplasty electively scheduled on 2 separate dates. The primary outcome was rate of adductor canal catheter utilization as a measure of adherence to the clinical pathway. Other outcomes included rates of neuraxial anesthesia and minor and major perioperative complications.We analyzed data for 103 unique patients. The interval between surgeries was a median of 261 days (10th-90th percentile, 138-534 days). All 103 patients had adductor canal catheters for both the first and second surgeries (P0.999). Forty-one percent of patients had the same surgeon for both surgeries, but only 2% had the same anesthesiologist (P0.001). From the first to the second surgery, utilization of neuraxial anesthesia increased from 51% to 68%, respectively (P = 0.005). There were no differences in minor or major complications.For staged bilateral knee arthroplasty patients, 100% clinical pathway adherence including perineural catheters and multimodal analgesia is feasible despite multiple variables. We believe that patient-centered acute pain management requires consistent and reliable delivery of care.

Background Total knee arthroplasty (TKA) designs continue to be modified to optimize patient's outcome. This study was designed to compare clinical and radiological results of classic worldwide used TKA posterior-stabilized (PS) design to those of its recent evolution. Methods A consecutive group of 100 patients undergoing TKA using a classic cemented fixed-bearing PS TKA system was matched by age, gender, body max index to 100 patients having the newer cemented fixed-bearing PS design, both by the same manufacturer. Patients were assessed preoperatively, at 12 months and at 24 months minimum follow-up (range, 24-46) in a standard prospective fashion. The outcome assessments used were the Oxford Knee Score, the Knee Society Score, range of motion, and a satisfaction survey. A 2-sample t test comparing the 2 groups was performed. Results No patients were lost at follow-up. At 2-year follow-up, differences in clinical and radiological Knee Society Score ( P = .09), Oxford Score ( P = .08), and overall satisfaction rate did not reach statistical significance. Implant group 2 showed a statistically significant decrease in postoperative anterior knee pain ( P = .006). At final follow-up, 16% of group 1 knees achieved > 130° flexion compared with 37% in group 2 ( P = .0009). There were 2 revisions for any reason in group 1 and none in group 2. Conclusions Design modifications applied to the newer TKA system allowed greater flexion and lower patellofemoral complications but did not appear to achieve better overall clinical scores.

Purpose: medial opening-wedge osteotomy is a widely performed procedure used to treat moderate isolated medial knee osteoarthritis. Historically, the literature has contained reports showing satisfactory midterm results when accurate patient selection and precise surgical techniques were applied. This study was conducted to investigate the clinical and radiographic seven- to twelve-year results of opening-wedge high tibial osteotomy in a consecutive series of patients affected by varus knee malalignment with isolated medial compartment degenerative joint disease. Methods: we reviewed a case series of 147 medial opening-wedge high tibial osteotomies at an average follow-up of 9.5 years. Endpoints for evaluation included the reporting of adverse effects, radiographic evidence of bone union, radiographic changes in the correction angle during union, and clinical and functional final outcomes. Results: good or excellent results were obtained in 94% of the cases: the patients reported no major complications related to the opening-wedge high tibial osteotomy surgical technique, bone graft resorption, implant choice or postoperative rehabilitation protocol. At final follow-up, the average hip-knee angle was 4° of valgus without major loss of correction during the healing process. A statistically significant change in the patellar height was detected postoperatively, with a trend towards patella infera. Conclusions: medial opening-wedge high tibial osteotomy is still a reliable method for correcting varus deformity while producing stable fixation, thus allowing satisfactory stability, adequate bone healing and satisfactory mid- to long-term results. Level of evidence: Level IV, therapeutic cases series.

There is no present consensus on the most reliable anatomical landmarks or axes for tibial rotational alignment in total knee arthroplasty (TKA). The goal was therefore to review the literature and compare accuracy and repeatability of different axes for tibial baseplate rotation in TKA. Medline and Embase were searched for articles that reported accuracy in terms of error or discrepancy from the trans-epicondylar axes (TEA), and/or repeatability in terms of intraclass correlation coefficient, of one or more axes used for tibial baseplate rotation in TKA. Twenty-one articles met criteria, and their data were extracted and tabulated. The selected articles evaluated 15 different axes, 13 for reliability, 12 for repeatability. The lowest errors or discrepancies from the projected TEA were reported for the original ‘Akagi line’ (posterior cruciate ligament posteriorly to medial border of tibial tuberosity), its variant using the sulcus of the tibial spines as anterior landmark, as well as the anterior tibial border and the curve-on-curve technique. The best inter-observer repeatabilities were reported for ‘Akagi line’ variants that use the geometric centre of the tibial plateau posteriorly and the medial border of the tibial tuberosity, or the medial sixth of the patellar tendon anteriorly. Considering accuracy and repeatability simultaneously, only two axes were found to satisfy both criteria consistently: the original ‘Akagi line’ and the anterior tibial border. Because of the small number of studies found, the collected evidence remains insufficient to recommend reference axes for intra-operative rotational alignment of the tibial baseplate in TKA. A combination of two or more anatomical landmarks or projected axes could be used to ensure adequate tibial baseplate rotation, while considering individual patient morphology and implant design to optimize knee kinematics and prevent prosthetic overhang. Level IV, systematic review of level III and IV studies.

A new philosophy of science and medicine had spread throughout the 17th-century Italy: the “Scientific Revolution.” Giovanni Alfonso Borelli (1608–1679) was one of the most charismatic and brilliant scientists of his generation in Europe. He extended to biology the rigorous analytic methods developed by his indirect mentor Galileo in the field of mechanics. In his masterpiece “De Motu Animalium,” Borelli analyzed structure, motion, balance, and forces concerning almost all the principal joints of the human body, in static and dynamic situations. In particular, he accurately studied the anatomy and biomechanics of the knee joint. He sustained that femoral condyles shift backward during flexion, allowing a wider range of movement. Furthermore, he observed that, when the knee flexes, the lateral condyle moves backward more than the medial condyle: this concept is nowadays known as medial pivoting. The aim of this article is to describe the life and work of this important Italian scientist and to present his unrecognized contribution to modern knee biomechanics.

Revision total knee arthroplasty (TKA) in the setting of major bone deficiency and/or soft tissue laxity might require increasing levels of constraint to restore knee stability. However, increasing the level of constraint not always correlates with mid-to-long-term satisfactory results. Recently, modular components as tantalum cones and titanium sleeves have been introduced to the market with the goal of obtaining better fixation where bone deficiency is an issue; theoretically, satisfactory meta-diaphyseal fixation can reduce the mechanical stress at the level of the joint line, reducing the need for high levels of constraint. This article reviews the recent literature on the surgical management of the unstable TKA with the goal to propose a modern surgical algorithm for adult reconstruction surgeons.

A rectangular and symmetrical gap in flexion as well as in extension is mandatory to achieve good outcomes and good long-term results in total knee arthroplasty (TKA) using classical designs. Recently, as showed in several fluoroscopic studies, different modern designs (medial congruent or sagittally stable implants) have been demonstrated to better reproduce the more physiological medial pivoting (MP) biomechanics of the normal knee when compared to classical postero-stabilized (PS) and cruciate-retaining (CR) designs. These modern designs, characterized by different level of conformity, might require adopting a different surgical technique in terms of soft tissue balancing technique for primary TKA. In such cases, the current authors suggest to reproduce a slightly asymmetric extension and flexion gaps with a tighter medial then lateral compartment to re-establish the MP kinematics of the normal knee.

Purpose: this study was conducted to compare the quantity of intercondylar bone removed during femoral box osteotomy for implantation of three contemporary posterior stabilized (PS) total knee arthroplasty designs: Sigma PS (DePuy), Vanguard (Biomet) and Persona (Zimmer). Methods: we compared the maximum volumetric bone resection required for the housing of the PS mechanism of these three designs. Bone removal by each PS box cutting jig was three-dimensionally measured. The differences between the three designs were analyzed by the Kruskal-Wallis test. The Mann-Whitney U-test was used for pairwise comparisons. The level of significance was set at p Results: for small-size implants, the average box osteotomy volume of Persona was significantly smaller than the Vanguard and Sigma PS volumes (p=0.003). The mean difference between Vanguard and Sigma PS (p=0.01) was also significant. For medium size implants, the mean difference between Persona and Sigma PS (p=0.008) and the mean difference between Vanguard and Sigma PS (p=0.01) were statistically significant. For large size implants, the mean difference between Vanguard and Sigma PS (p=0.01) and the mean difference between Sigma PS and Persona (p=0.008) were statistically significant. Conclusions: irrespective of implant size, the Persona cutting jig always resected significantly less bone than did Vanguard and Sigma PS. Clinical Relevance: although this study does not establish any clinical relevance of removing more or less bone at primary TKA, its results suggest that if a PS design is indicated, it is preferable to select a model which resects less distal femoral bone.

We describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining an infected total knee arthroplasty. This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration using calcium sulfate beads. The combination of three different surgical techniques (methylene blue staining, argon beam electrical stimulation, and chlorhexidine gluconate brushing) might enhance the identification, disruption, and finally removal of the bacterial biofilm, which is the main responsible of antibiotics and antibodies resistance. The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous periprosthetic joint infection.

Anterior knee pain following TKA performed utilizing the PFC Sigma system still represents a cause of failure. The purpose of this study was to evaluate whether or not a recent change in the femoral design (PFC Sigma PS) had a positive impact on the patello-femoral complication rate. A consecutive series of 100 TKA using the PFC Sigma PS system was followed prospectively for a minimum of 3 years. All patellae were replaced and a standard lateral release was never performed. Radiographic analysis following the Knee Society Score (KSS) included antero-posterior weight-bearing, lateral and bilateral axial radiographs. TKA rotational alignment was recorded at the final follow-up in 30 consecutive knees by performing a CT evaluation. Good to excellent clinical results according to the KSS were achieved in 94 % of the knees. Survival without need of reoperation for any reason was 98 % at 3 years minimum follow-up; two reoperations were done for removal of fibromatous intra-articular tissue (“Clunk syndrome”). There were no revisions for septic or aseptic loosening of the components. The mean ROM improved from 104° preoperatively to 115° (97°–132°) postoperatively: postoperative flexion was 120° or more in 58 % of the knees. Severe anterior knee pain was present in 9 % of patients. Radiographic evaluation showed 90 knees with a tibio-femoral anatomical axis between 8° and 2° of valgus (±3° from the intraoperative goal). CT evaluation of 30 consecutive knees showed that the femoral component positioning in relationship to the trans-epicondylar axis had only 2.80° of external rotation (±2.10°) with respect to a planned external rotation of 3°. This difference was statistically significant. Although the PFC Sigma PS system provides good and predictable results for tricompartmental arthritis of the knee, anterior mechanism complications still represent a reason for dissatisfaction in a substantial group of patients.

Accurate preoperative planning is mandatory for a successful total hip arthroplasty (THA). Templating helps to achieve multiple technical goals, including offset restoration, leg-length equality, and components positioning. This study aims to measure how successful a new stepwise method for preoperative radiographic templating is in achieving postoperative restoration of anatomy. We measured the relationship of several radiographic landmarks on the affected limb in comparison to the unaffected limb to define the appropriate position of the components. One hundred consecutive patients with unilateral disease undergoing THA were retrospectively analyzed. The preoperative templates were compared with the postoperative radiographs. Accuracy in achieving the desired offset, leg-length discrepancy within 5 mm, was 93 % and 100 % respectively. Acetabular component positioning within 2° was replicated in 92 %. We conclude that this technique can help the surgeon to accurately reproduce the anatomy of the contralateral unaffected hip.

Purpose: historically, the original CLS Spotorno Stem has demonstrated excellent survival. The design of this stem was recently modified, resulting in the introduction of a shorter, modular version (CLS Brevius). The purpose of the current study was to evaluate the functional, radiological and survivorship outcomes of the cementless CLS Brevius Stem in a multi-surgeon, single center, consecutive series study at two years post-surgery. Methods: the Authors performed 170 total hip arthroplasties in 155 patients using the shorter, tripletaper stem design (CLS Brevius). The patients’ diagnoses were primary hip osteoarthritis (OA) in 74.4%, secondary hip OA in 22.6%, and post-traumatic hip OA in 3%. All operations were performed through a mini-posterior approach, with the patient in the lateral decubitus position. The mean follow-up was 32 months (24-44 months). Outcome was assessed using the Harris Hip Score (HHS). Results: the mean HHS improved from 32 preoperatively to 92 points at final follow-up, while the stem survival rate was 99.4%.Overall, the results were excellent in148 hips (87%), good in 14 hips (8.2%), fair in six hips (3.6%), and poor in two hips (1.2%). Intraoperative complications included a calcar fissure in three hips (1.7%). Correct femoral offset was reproduced in 97% while the planned center of hip rotation was achieved in 98%. Only one hip underwent early stem revision; this was due to major subsidence. Conclusions: the modified CLS stem design showed excellent short-term results with a low rate of early postoperative complications. One of the main findings of this study was the high correlation between the planned femoral offset and center of hip rotation and the final radiographic measurements. This high reproducibility, which indicates the ability of the system to restore normal hip anatomy, is indeed due to the extensive modularity that characterizes this stem system. Long-term follow-up studies are necessary to fully compare the outcomes of the new design with its highly successful predecessor. Level of Evidence: Level IV, therapeutic cases series.

The objective of this study was to evaluate the radiological and clinical correlations between implant design and patellar positioning in patients who underwent TKA utilizing femoral implants with modern designs.Thirty consecutive PFC PS Sigma TKAs, characterized by a new prolonged anterior flange and a "smoother" trochlea, were prospectively reviewed. All patellae were replaced. All patients were evaluated pre-operatively and prospectively at two years follow-up both clinically according to the Knee Society score as well as radiographically. This included computed tomography (CT); patellar tilt, patellar conformity angle, patellar lateralization, and femoral component external-rotation in relation to the clinical trans-epicondylar axis.Average patellar tilt at follow-up was 3° (±7.5°) with respect to a pre-operative 18.5° (±8.5°). Average patellar congruence angle at follow-up was -3° (range, -11° to +9°) with respect to a pre-operative 10.3° (range, + 1.5° to 25.5°). Average lateralization index at follow-up was 2.7 mm (range, -3.4 mm to +7.1 mm) with respect to a pre-operative 12.2 mm (± 4.8 mm). Femoral component positioning related to the trans-epicondylar axis showed an external rotation of 2.80° (± 2.10°) at follow-up with respect to 5.7° (± 1.80°). Clinically, two (6.6%) patients reported patello-femoral complications related to imperfections in the surgical technique more than the implant's design.This study highlighted that modern femoral designs in TKA allow for a correct reproducibility of a normal patello-femoral conformity. Strict surgical principles are paramount to avoid patello-femoral complications even when modern implants are used.

Purpose: to compare the anterior tibial surface curvature, the Akagi’s line and the medial third of the tibial tubercle in order to assess which is the most reliable landmark for correct tibial component rotational positioning in total knee arthroplasty. Methods: three independent investigators reviewed 124 knee MRI scans. The most suitable tibial baseplate tracing for the Nexgen Total Knee System (Zimmer, Warsaw, USA) was superimposed on the scan matching the anterior tibial cortex with the anterior aspect of the baseplate. The rotation of the tibial baseplate tracing was calculated with respect to the transepicondylar axis (TEA), the medial third of the tibial tubercle line, Akagi’s line and the femoral posterior condylar axis (PCA). Customized software was created and used for analysis of the MRI datasets.The reliability of each measurement was then calculated by using the intraclass correlation coefficient for interobserver agreement. Results: observer agreement on the position of the Akagi’s line was within 3° in 64% of the cases and within 5°in 85% of the cases. Agreement on the position of the medial third of the tibial tubercle was within 3°in 29% of the cases and within 5°in 70% of the cases. Agreement on the localization of the anterior tibial surface curvature was within 3°in 89% of the cases and within 5°in 99% of the cases. Component alignment along the anterior cortex guaranteed full matching ± 3° with the epicondylar axis in 75% of the knees. Conclusions: the anterior tibial surface curvature was found to be a more reliable and more easily identifiable landmark for correct tibial component alignment than either Akagi’s line or the medial third of the tibialtubercle. Level of evidence: level III, retrospective cohort study.

This study evaluated the influence of modern tibial baseplate designs when using the anterior tibial cortex as a primary rotational landmark for the tibial baseplate in TKA. Eighty patients undergoing TKA were randomized in two groups. Group 1 included 25 females and 15 males receiving a posterior-stabilized (PS) symmetric tibial baseplate while Group 2 included 24 females and 16 males receiving a PS anatomical tibial component. Identical surgical technique, including the use of the surgical transepicondylar femoral axis (sTEA) and the anterior tibial cortex (“Curve-on-Curve”) as rotational alignment landmarks, was used. All patients underwent CT evaluation performed with the knee in full extension. Three observers independently measured the rotational alignment of the tibial component in relation to the sTEA. The rotational alignment of the symmetric baseplate showed an average external rotation of 1.3° (minimum 5°, maximum −1°): 91% of the knees showed 0 ± 3° with respect to the surgical sTEA, being internally rotated in 20%. The rotational alignment of the anatomical baseplate showed an average external rotation of 4.1° (minimum 0.4°, maximum 8.9°): only 47.5% of the knees showed 0 ± 3°, being externally rotated in 100%. The difference between the two groups was statistically significant. This study confirms the reliability of the “Curve-on-Curve” technique as an adequate rotational alignment anatomical landmark in TKA: the use of an asymmetric tibial baseplate might lead to external rotation of the tibial component when this technique is intraoperatively chosen.

Total knee arthroplasty has been a very successful procedure in the treatment of end-stage arthritis of the knee. However, this procedure has traditionally required an extensive approach that might be linked to an arduous recovery period because of postoperative quadriceps weakness. The proposed benefits of minimally invasive approaches include improved gain of early flexion, decreased use of analgesics, improved postoperative quadriceps function, decreased blood loss, shorter length of hospital stay, cosmetically better smaller incision, early recovery, and rapid rehabilitation.

Patients with anterior cruciate ligament instability resulting from incomplete tears or elongation in continuity without ligament detachment historically have been treated conservatively or by graft replacement. The literature is sparse regarding alternative treatments. The current study presents experience using monopolar thermal repair on 28 consecutive knees with partial anterior cruciate ligament tears all symptomatically unstable. All lesions were less than 6 months old (average, 77 days; range, 7-180 days) and with a difference of 6 mm or more (average, 9 mm; range, 6-13 mm) when comparing both knees using KT-1000 evaluation. Incomplete tears of the anterior cruciate ligament were seen at arthroscopic evaluation. The rehabilitation protocol included use of a brace for at least 6 weeks and progressive weightbearing. A 2-year minimum followup (range, 24-35 months) was done in all patients following the International Knee Documentation Committee guidelines. The overall outcome was normal or nearly normal in 96% of the patients. One failure occurred at 8 weeks. Twenty-six knees had a KT-1000 difference between 0 and 2 mm (average, 1.9 mm). Because thermal application causes death to some of the cells directly treated, it should be taken into account in selection and application. Immediately after thermal use, the anterior cruciate ligament, although thicker and tighter, is at first weaker than normal. Rehabilitation and compliance are critical during early ligament healing. This procedure seems to be a reasonable alternative to anterior cruciate ligament grafting in selected patients.

A review of postoperative infected anterior cruciate ligament reconstructions was done on 3500 consecutive arthroscopic procedures. The purpose was to assess incidence, diagnosis, treatment, and outcome factors. Six postoperative in-traarticular infections were detected. Average followup was 3 years (range, 2-8 years). The rate of infection was 0.14%. Five men and one woman with a median age of 32.5 years (range, 20-51 years) comprised the study group. The average interval from the onset of symptoms to the initial arthroscopic intervention was 7.5 days (range, 2-20 days). Staphylococcus aureus was present in three knees, Staphylococcus epidermidis in two, and Streptococcus nonhemolytic in one. All patients had initial arthroscopic debridement and lavage followed by 6 weeks of intravenous antibiotics. Two grafts were removed: one patient had delayed ligament reconstruction and the other had total knee arthroplasty. The remaining patients had full range of motion. In the group with the best result, two patients had Staphylococcus epidermidis and one had Staphylococcus aureus, which was treated 2 days after clinical symptoms began. The other two patients infected with Staphylococcus aureus had unsatisfactory results. Anterior cruciate ligament infection is rare, but diagnosable. When treated early with appropriate antibiotic therapy and arthroscopic debridement, four of six grafts were retained. If the infection does not respond rapidly to early therapy, then graft removal is an option.

Venous thromboembolism represents a frequent complication following total joint arthroplasty (TJA). Many international guidelines for deep venous thrombosis (DVT) prophylaxis do not recommend a preoperative lower limb duplex ultrasound before total hip and knee arthroplasty. This study is aimed at determining whether a preoperative Doppler ultrasonographic screening is cost-effective as a DVT and pulmonary embolism prevention device. A series of 2,678 consecutive patients undergoing TJA received preoperative assessment for DVT by bilateral lower limbs color Doppler ultrasonography. The study group included 1,697 females (63.3 %) and 981 males (36.7 %): all patients were included regardless of absence of previous vascular symptoms. Assessment included examination of bilateral common femoral, superficial femoral, popliteal, anterior tibial and posterior tibial veins. Preoperative ultrasound screening highlighted the presence of DVTs in 120 patients (4.5 %). Those patients were withdrawn from the operative schedule and began DVT treatment with personalized doses of LMWH (low molecular weight heparin). Patients underwent TJA procedure once the preoperative Doppler ultrasonography revealed absence of DVT (minimum 3 months; maximum 6 months). This study discovered a preoperative asymptomatic DVT in a consistent number of patients just before undergoing TJA: without screening they were at risk of developing possible life-threatening perioperative pathologies. Therefore we consider it prudent to perform a preoperative Doppler ultrasonography to detect any pre-existing DVT, especially in patients who are considered to be at high risk.

Purpose: periprosthetic joint infection (PJI) accounts for 25% of failed total knee arthroplasties (TKAs) and 15% of failed total hip arthroplasties (THAs). The purpose of the present study was to design a multidisciplinary diagnostic algorithm to detect a PJI as cause of a painful TKA or THA. Methods: from April 2010 to October 2012, 111 patients with suspected PJI were evaluated. The study group comprised 75 females and 36 males with an average age of 71 years (range, 48 to 94 years). Eightyfour patients had a painful THA, while 27 reported a painful TKA. The stepwise diagnostic algorithm, applied in all the patients, included: measurement of serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels; imaging studies, including standard radiological examination, standard technetium-99m-methylene diphosphonate (MDP) bone scan (if positive, confirmation by LeukoScan was obtained); and joint aspiration with analysis of synovial fluid. Results: following application of the stepwise diagnostic algorithm, 24 out of our 111 screened patients were classified as having a suspected PJI (21.7%). CRP and ESR levels were negative in 84 and positive in 17 cases; 93.7% of the patients had a positive technetium-labeled bone scan, and 23% a positive Leuko - Scan. Preoperative synovial fluid analysis was positive in 13.5%; analysis of synovial fluid obtained by preoperative aspiration showed a leucocyte count of > 3000 cells μ/l in 52% of the patients. Conclusions: the present study showed that the diagnosis of PJI requires the application of a multimodal diagnostic protocol in order to avoid complications related to surgical revision of a misdiagnosed “silent” PJI. Level of evidence: Level IV, therapeutic case series.

Historically, general anesthesia has been the "gold standard" for surgeons and patients when major hip surgery is being done. The recent introductions of improved techniques and catheters for continuous peripheral nerve blocks have made regional anesthesia more attractive to patients and surgeons. We focus on current trends and future directions in perioperative pain management for major orthopaedic procedures done on the hip. The use of epidural or spinal anesthesia during major hip surgery has been linked to a reduced risk of perioperative complications like deep venous thrombosis, less deterioration of cerebral and pulmonary functions in patients who are at high risk for complications, and overall reduced blood loss. In addition, continuous peripheral nerve blocks showed effective and safe postoperative pain control, allowing for lower opioids consumption, improved and earlier rehabilitation, and high patient satisfaction. Accurate patient selection and patient education are fundamental for the success of any regional anesthesia technique. Modern regional anesthesia for major hip surgery includes the use of a single shot and continuous epidural injections, single-shot and continuous spinal injection, continuous lumbar plexus blockade, and continuous peripheral blockade of the femoral and sciatic nerves. Continuous peripheral nerve blocks represent an adjunctive, effective, and safe technique for postoperative pain control after total hip arthroplasty. Future directions in postoperative pain control include the creation of a comprehensive system that supervises the use of continuous peripheral nerve blocks outside the acute inpatient setting for few days following the surgical procedure.Therapeutic study, Level V (expert opinion). See the Guidelines for Authors for a complete description of levels of evidence.

We prospectively studied 100 Insall-Burstein Posterior Stabilized II total knee arthroplasties (Zimmer Inc, Warsaw, IN) consecutively implanted in 91 patients with osteoarthritis. We reviewed 92 knees in 85 patients at a mean follow-up of 7.5 years (range, 5.3-9.5 years). According to the Knee Society score, 78 (85%) results were excellent, 11 (12%) were good, and 3 (3%) were fair or poor. The unsatisfactory results were attributed to patellofemoral pain with a low patella (2 knees) and to valgus alignment and medial laxity (1 knee). Flexion at follow-up averaged 116 degrees. Nonprogressive radiolucent lines were present around 30% of the tibial components. There was only 1 small osteolytic lesion around the tibial plateau. We observed no aspetic loosening, infection, or patella stress fracture. Survivorship analysis in the worst-case scenario showed a 90.9% success rate at 8 years.

Three different knee replacements, with three trochlear designs, were prospectively evaluated clinically and radiographically for patellar function and presence of patellar complications. They included the Insall-Burstein (IB) I and the IB-II (posterior cruciate ligament substituting) and the Meniscal Bearing Knee (MBK; posterior cruciate ligament recession). The trochlea of the IB-I was short and shallow with an anterior sharp edge of the intercondylar box (later modified to a smoother edge) and the femoral component had a prominent "shoulder." In the IB-II the trochlea was deeper to allow for soft tissue clearance. In the MBK the trochlea was more prolonged, with R and L components and the "shoulder" was less prominent. In all the cases the patella was resurfaced with an all polyethylene dome prosthesis. Knees with tibiofemoral problems were excluded. From the data of the present study the following conclusions can be drawn: (a) The most frequent problem was impingement (clunks) with the early version of the IB-I. Smoothening of the anterior edge significantly reduced the incidence of clunks to 5% in the modified IB I. (b) With the IB-II deepening the trochlea for soft tissue clearance improved the degree, not the incidence of clunks (4.5%), compared to the modified IB I. (c) With the MBK clunks were very rare and patellar function improved. (d) Throughout the three series patellar stress fractures and instability were rare and loosening or wear not evident. (e) Normal function (including stairs ascending and descending) can be expected in over 80% of category A patients. (f) Of the various radiological parameters only patella baja was correlated with symptoms in the IB prostheses. (g) We still prefer the dome design because is more tolerant and with cold flow may better conform to the trochlea increasing contact area.