Medially congruent total knee arthroplasty in valgus knee deformities yields satisfactory outcomes: a multicenter, international study.

PURPOSE: 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. METHODS: 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. RESULTS: 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 < 0.001) at the time of the last follow-up. Preoperative knee extension significantly improved from 3° (range - 15° to 20°) to 1° (range - 5° to 5°) of flexion at the last follow-up in all the patients. KSS and KSS Functional scores were 89 (range 65-100) and 82 points (range 55-100), respectively. The FJS obtained at the last follow-up was 72 (range 49-88). Two patients (2.5%) had major postoperative complications (one periprosthetic joint infection; one postoperative patellar fracture) requiring surgical interventions. CONCLUSIONS: In different surgeon's hands, the use of a modern medially congruent TKA design yielded good clinical outcomes at 2 years in a consecutive series of TKA in valgus arthritic knees. Postoperative instability was not recorded in this series and this finding was related to the high conformity design of the MC polyethylene insert, which significantly differs from classical posterior-stabilized (PS) designs. LEVEL OF EVIDENCE: IV.

"Recommendations for periprosthetic joint infections (PJI) prevention: the European Knee Associates (EKA)-International Committee American Association of Hip and Knee Surgeons (AAHKS)-Arthroplasty Society in Asia (ASIA) survey of members".

PURPOSE: 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. METHODS: 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. RESULTS: 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 < 35; 30.9% BMI < 40; 17.2% BMI < 45; (C) Nutritional status: 55.3% do not screen; among those who screen their patients (44.7%), albumin is the single most used marker (86.3%); (D) Hyperglycemia/Diabetes: 83.3% check this comorbidity; 88.1% use HgbA1C as single best screening test; (E) MRSA nasal colonization: 63.7% do not test; 28.9% test all patients; 7.4% test selectively. Intraoperative: (A) Antibiotic prophylaxis in high-risk patients: 43.4% use single antibiotic for 24 h; 21.3% use double antibiotic for 24 h; 14.2% use single/double antibiotic for 7 days postoperatively; (B) Skin-cleansing: 68.7% at home (45.6% chlorhexidine sponge; 11.9% clippers); (C) Intraoperative skin disinfection: 46.9% single chlorhexidine; 25% double chlorhexidine-povidone-iodine;15.4% single povidone-iodine; (D) Tranexamic acid (TXA) to reduce bleeding/SSI: 96% yes (51% double IV dose, 35.2% single IV dose, 23.6% intra-articular injection); (E) Surgical suction drain: 52% do not use drains; 19.7% use a drain < 24 h; (F) Intra-articular lavage: 64.9% use only saline; 28.1% use dilute povidone-iodine; (G) Antibiotic local delivery to prevent PJI: 82.4% use antibiotic-added cement. Postoperative: (A) Routine monitoring of PJI serologic markers: 42% only in symptomatic patients; 34.2% do not; 20.8% in all patients; (B) Serologic markers to rule in/out PJI: 95.9% CRP; 71% SEDRATE; 60.6% WBC; (C) Synovial fluid test to rule in/out PJI: 79.6% culture/sensitivity; 69.5% WBC count; 31.4% CRP. CONCLUSIONS: This survey demonstrated that notable differences still exist in the application of PJI preventive measures across different geographic areas: Optimizing the patient preoperatively and applying multimodal intraoperative strategies represent newer, clinically relevant steps in the effort to reduce the burden of PJI. More uniform guidelines still need to be produced from international scientific societies in order facilitate a more comprehensive approach to this devastating complication. LEVEL OF EVIDENCE: IV.

Proximal humeral fractures treated with a low-profile plate with enhanced fixation properties.

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.

Kinetic Sensors for Ligament Balance and Kinematic Evaluation in Anatomic Bi-Cruciate Stabilized Total Knee Arthroplasty.

Sensor technology was introduced to intraoperatively analyse the differential pressure between the medial and lateral compartments of the knee during primary TKA using a sensor to assess if further balancing procedures are needed to achieve a "balanced" knee. The prognostic role of epidemiological and radiological parameters was also analysed. A consecutive series of 21 patients with primary knee osteoarthritis were enrolled and programmed for TKA in our unit between 1 September 2020 and 31 March 2021. The VERASENSE Knee System (OrthoSensor Inc., Dania Beach, FL, USA) has been proposed as an instrument that quantifies the differential pressure between the compartments of the knee intraoperatively throughout the full range of motion during primary TKA, designed with a J-curve anatomical femoral design and a PS "medially congruent" polyethylene insert. Thirteen patients (61.90%) showed a "balanced" knee, and eight patients (38.10%) showed an intra-operative "unbalanced" knee and required additional procedures. A total of 13 additional balancing procedures were performed. At the end of surgical knee procedures, a quantitatively balanced knee was obtained in all patients. In addition, a correlation was found between the compartment pressure of phase I and phase II at 10° of flexion and higher absolute pressures were found in the medial compartment than in the lateral compartment in each ROM degree investigated. Moreover, those pressure values showed a trend to decrease with the increase in flexion degrees in both compartments. The "Kinetic Tracking" function displays the knee's dynamic motion through the full ROM to evaluate joint kinetics. The obtained kinetic traces reproduced the knee's medial pivot and femoral rollback, mimicking natural knee biomechanics. Moreover, we reported a statistically significant correlation between the need for soft tissue or bone resection rebalancing and severity of the initial coronal deformity (>10°) and a preoperative JLCA value >2°. The use of quantitative sensor-guided pressure evaluation during TKA leads to a more reproducible "balanced" knee. The surgeon, evaluating radiological parameters before surgery, may anticipate difficulties in knee balance and require those devices to achieve the desired result objectively.

No clinical differences at the 2-year follow-up between single radius and J-curve medial pivot total knee arthroplasty in the treatment of neutral or varus knees.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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. LEVEL OF EVIDENCE: Retrospective case-control study, Level III.

Effect of polyethylene conformity on total knee arthroplasty early clinical outcomes.

PURPOSE: 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. METHODS: 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. RESULTS: 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.). CONCLUSION: 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. LEVEL OF EVIDENCE: III.

The effects of femoral component design on the patello-femoral joint in a PS total knee arthroplasty.

INTRODUCTION: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Bi-cruciate retaining total knee arthroplasty is here to stay: A consecutive series transitioning from manual instrumentation to enabling technologies.

BACKGROUND: Bicruciate-retaining (BCR) total knee arthroplasty (TKA) has seen renewed interest due to the potential for more natural knee kinematics with anterior cruciate ligament (ACL) retention. OBJECTIVE: The present study attempts to determine differences in the 2-year survivorship and patient-reported outcomes between two surgical strategies (traditional instrumentation versus robotics) applied to the extensive use of a modern, 2nd generation BCR TKA design. METHODS: We performed a retrospective study with prospectively collected data of 113 patients who underwent primary TKA between 2018 and 2020 using a 2nd generation BCR TKA implant. Patient demographics, PROMS, and intra/post-operative complications were collected. Patients were also evaluated according to the use or not of robotics. A Kaplan-Meier analysis was used to evaluate revision-free survival at follow up. RESULTS: 102 patients were enrolled: 90 received traditional surgery and 12 robotic-assisted surgery. The mean age was 68 years (SD 7.76) with an average BMI of 29.6 kg/m2 (SD 3.56). The mean follow up (FU) was 32.4 ± 6.2 months (range 24-45 months). Survivorship at 2 years was 98% (95% CI: 92.4-99.5). Revisions/reoperations were performed for anterior cruciate ligament (ACL) tear (1/4), pain (1/4), arthrofibrosis (1/4) and acute periprosthetic joint infection (PJI) (1/4). At final FU, 92 patients (90.2%) considered themselves satisfied, showing a mean OKS of 40.6 (SD 5.1) and a mean FKS of 76.7 (SD 11.8). No differences in the outcome were found between traditional and robotic-assisted procedures. CONCLUSION: The modern BCR design evaluated in this study achieved excellent results in terms of implant survivorship, low rate of reoperation and clinical results, independently from the use of enabling technologies.

Asymmetric gap balancing improves knee kinematic following primary total knee arthroplasty.

PURPOSE: The purpose of this study was to demonstrate closer-to-normal knee kinematics following primary total knee arthroplasty (TKA) performed establishing asymmetric gap balancing intraoperatively. MATERIAL AND METHOD: Two age-, sex-, BMI-matched groups of patients underwent medially stabilized TKA because of isolated knee disease. Group A (12 patients) underwent "unrestricted" kinematic alignment (uKA) according to Howell while group B (15 patients) received robot-assisted "simplified" KA (sKA) with an alignment goal (Hip-Knee-Ankle axis-HKA) ± 5° respect to the mechanical axis. Intraoperatively, in group B, the flexion gap at 90° was first set at an average of 1.5 mm (0-5 mm; SD 4.4 mm) tighter in the medial compartment with respect to the lateral; in the same way, the extension gap was then set at an average of 2.0 mm (0-4.5 mm; SD 3.1 mm) tighter in the medial compartment with respect to the lateral. All patients, including a non-arthritic cohort (group C: 5 controls) underwent gait analysis using an instrumented treadmill (WalkerView-WV) equipped with an instrumented belt armed with a 3D video camera. The WV software evaluated multiple spatiotemporal and kinematic parameters, including: (1) contact time (s); (2) knee ROM during gait cycle; (3) step length percentage with respect to total gait (%) and pure step length (cm). Statistical analyses included t-Test and ANOVA and were conducted by using SPSS. RESULTS: At the final FU, significant differences were noted during gait between the two TKA groups (uKA-sKA) and the controls. Both TKA groups showed superior mean contact time on the surgical knee (uKA 1 s; sKA 0.97 s) as compared to the controls (0.72 s) (P = 0.002) while no differences were found between them (P = 0.11). TKA groups showed a lower, maximum ROM in the surgical knee (mean uKA 36º; mean sKA 49º) relative to the controls (mean 57º) (P < 0.05) but a statistical difference was found between them (P = 0.003). Both TKA groups showed a higher step length percentage with respect to the total gait and a shorter step length on the surgical side (uKA: mean 8.28% and mean step length 35.5 cm; sKA: mean 8.38% and mean step length 34.6 cm) in comparison to the controls (mean 3.38%; mean step length 71.4 cm) (P < 0.05) while no statistical differences were found between them. CONCLUSION: To our knowledge, this was the first study to exhibit the kinematic advantages of a slightly asymmetric gap balancing during KA TKA. Combining a medially-stabilized implant design and a surgical technique aiming to obtain a tighter medial compartment represents a promising approach to improve outcomes after TKA.

A multimodal approach in total hip arthroplasty preoperative templating.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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 %. CONCLUSION: We conclude that this technique can help the surgeon to accurately reproduce the anatomy of the contralateral unaffected hip.

Direct anterior approach in total hip arthroplasty: influence of stem length on clinical and radiological outcomes at medium-term follow-up.

PURPOSE: 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). METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Native knee kinematics is not reproduced after sensor guided cruciates substituting total knee arthroplasty.

PURPOSE: Gait analysis was used to evaluate knee kinematics in patients who underwent successful primary total knee arthroplasty (TKA) using two modern bi-cruciate substituting designs. The knee joint was balanced intraoperatively using real-time sensor technology, developed to provide dynamic feedback regarding stability and tibiofemoral load. The authors hypothesized that major differences exist in gait parameters between healthy controls and post-TKA patients. METHODS: Ten patients who underwent successful TKA using bi-cruciate substituting designs were evaluated at a minimum of 9 months postoperatively using three-dimensional knee kinematic analysis; a multi-camera optoelectronic system and a force platform were used. Sensor-extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA) and knee rotational angle at heel-strike. Multiple gait analysis data from the study group were compared to a group of ten healthy controls who were matched by age, sex and BMI. Clinical outcome in the TKA group was also measured using the Knee injury and Osteoarthritis Outcome Score (KOOS). RESULTS: Clinically, at final follow-up, a statistically significant difference in pain, general symptoms, and activities of daily living was seen between the groups. From a gait analysis standpoint, TKA patients had significantly less rotation at heel strike (p = 0.04), lower late stance peak extension moments (p = 0.02), and less Knee Adduction Angle excursion during swing phase (p = 0.04) compared to the control group. No statistically significant difference was observed for knee flexion angle at heel strike, knee adduction moment, or peak knee flexion moment between the groups. CONCLUSIONS: Modern bi-cruciate substituting TKA designs failed to reproduce normal knee kinematics. The lack of full knee extension during the stance phase, absence of the "screw-home mechanism" typical of an ACL functioning knee, and the reduced fluctuation in knee adduction angle during the swing phase still represent major proprioceptive and muscular recruitment differences between normal and replaced knees.

Debridement, Antibiotic Pearls, and Retention of the Implant (DAPRI) in the Treatment of Early Periprosthetic Joint Infections: A Consecutive Series.

INTRODUCTION: Periprosthetic joint infections (PJI) represent a devastating consequence following total joint arthroplasty (TJA). In this study, the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure (DAIR) to improve the possibilities of retaining an acutely infected TJA. MATERIALS AND METHODS: 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 in a setting of acute (<4 weeks from symptoms onset) PJI with pathogen identification. The combination of three different surgical techniques (tumor-like synovectomy, argon beam/acetic acid application and chlorhexidine gluconate brushing) aims to remove the bacterial biofilm from the implant without explanting the original hardware. RESULTS: In total, 62 patients met the acute infection criteria (<4 weeks of symptoms); there were 57 males and five females. The patients' average age at the time of treatment was 71 years (62-77) and the average BMI was 37 kg/m2. The micro-organism, always identified through synovial fluid analysis (culture, multiplex PCR or Next Generation Sequencing), was an aerobic Gram + in 76% (S. Coag-Neg 41%; S. aureus 16%), Gram-in 10% (E. coli 4%) and anaerobic Gram + in 4%. The DAPRI treatment was performed at an average of 3 days from symptoms onset (1-7 days). All patients underwent a 12-week course of post-operative antibiotic therapy (6 weeks I.V. and 6 weeks oral). All patients were available at the 2-year minimum FU (24-84 months). A total of 48 (77.5%) patients were infection-free at the final FU, while 14 patients underwent 2-stage revision for PJI recurrence. In total, four patients (6.4%) had a prolonged drainage from the wound after placement of the calcium sulphate beads. CONCLUSIONS: This study suggests that the DAPRI technique could represent a valid alternative to the classic DAIR procedure. The current authors do not recommend this procedure outside of the main inclusive criteria (acute scenario micro-organism identification).

Biomechanical considerations for an easily-restricted robot-assisted kinematic alignment: a surgical technique note.

BACKGROUND: In total knee arthroplasty, the normal kinematics of the knee may not be restored solely based on preoperative gait, fluoroscopic-based, and dynamic radiostereometric analyses. SURGICAL TECHNIQUE CASE PRESENTATION: This note introduced a 69-year-old male patient who sustained post-traumatic osteoarthritis of his right knee. He underwent robot-assisted total knee arthroplasty based on anatomical reproduction of knee stability during the swing phase of gait. The kinematic alignment was simply achieved within an easy-to-identified range after preoperative radiographic assessment, intraoperative landmarking and pre-validated osteotomy, and intraoperative range of motion testing. CONCLUSIONS: This novel technique allows personalized and imageless total knee arthroplasty. It provides a preliminary path in reproducing the anatomy alignment, natural collateral ligament laxity, and accurate component placement within safe-to-identified alignment boundaries.

Comparison between gaits after a medial pivot and posterior stabilized primary total knee arthroplasty: a systematic review of the literature.

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 < 0.05) a significantly higher peak of knee flexion angle during the swing phase, greater knee flexion angle at toe-off, an increased knee adduction angle, higher knee flexion and extension moment, increased anterior femoral roll during knee flexion and anterior translation on medial and lateral condyle during knee flexion compared to MP TKA. MP TKA showed statistically significant (P < 0.05) higher knee rotational moment and greater tibiofemoral external rotation motion during knee flexion than PS TKA. No statistically significant difference (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.

A Modified Technique for Two-Stage Revision in Knee PJI Treatment.

Knee PJIs represent one of the most important complications after joint replacement surgery. If the prerequisites for implant retention do not subsist, the surgical treatment of these conditions is performed using one-stage and two-stage revision techniques. In this study, an implemented two-stage revision technique was performed, adopting antibiotic calcium sulfate beads and tumor-like debridement guided by methylene blue, such as described for the DAPRI technique. The aim of the present study is to compare the implemented two-stage revision technique with the standard technique in order to assess its effectiveness. METHODS: Twenty patients affected by knee PJIs were prospectively enrolled in the study and underwent an implemented two-stage revision technique (Group A). Data collected and clinical results were compared with a matched control group treated with a standard two-stage technique (Group B). For each patient, the time of the reimplantation and length of antibiotic systemic therapy were recorded. Each patient underwent routine laboratory tests, including inflammatory markers. RESULTS: In Group A and in Group B, inflammatory markers normalized at 6.5 ± 1.1. weeks and 11.1 ± 2.3 weeks, respectively (p < 0.05). Also, the difference in length of antibiotic therapy and time to reimplantation were significantly shorter in Group A (p < 0.05). No recurrence of infection was found in Group A at the last follow-up. DISCUSSION: The implemented two-stage revision technique demonstrated a faster normalization of inflammatory markers, as well as a decrease in reimplantation time and duration of antibiotic therapy, compared to the traditional technique. The use of calcium sulfate antibiotic beads and tumor-like debridement seems to improve the results and reduce the time of healing. CONCLUSION: The implemented two-stage revision technique seems to improve the results and reduce the time of healing. This leads to a more rapid and less stressful course for the patient, as well as a reduction in health care costs.

Contemporary femoral designs in total knee arthroplasty: effects on the patello-femoral congruence.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.