A prospective study on outcome of patient-specific cones in revision knee arthroplasty.

BACKGROUND: Cones are known to be good substitutes for metaphyseal and diaphyseal bone loss during revision total knee arthroplasty (RTKA). Often the off-the-shelf cones do not fit to the individual patient's anatomy. New 3D-printing additive technologies allow to develop patient-specific cones. The aim of this prospective study was to describe their outcome. METHODS: From 2017 until 2020, 35 patient-specific titanium cones (15 femoral and 20 tibial) were implanted during 31 RTKAs (45% varus-valgus constrained implants and 55% rotating hinges). Clinical outcome was evaluated using KSS, WOMAC and FJS-12 scoring systems at 12 and 24 months. No patients were lost for follow-up. RESULTS: In all cases, there were no technical difficulties in adapting the cones to both the host bone and the revision implant. By the time of performing data analysis (January 2021), none of the 31 patients needed revision surgery for any reason. At 12 months of follow-up, the mean values of scores for knee function improved significantly from baseline (p < 0.01): KSS-103.00 (min 100-max 111, SD 5.35), WOMAC-16.5 (min 9-max 24, SD 6.45), FJS-12-61.60 (min 52-max 76, SD 9.20). At 24 months, the trend towards improvement of functional results continued but did not reached statistical significance comparing to 12 months: KSS was 105.92 (min 95-max 155, SD 16.18), WOMAC-14.07 (min 0-max 42, SD 12.42), FJS-12-83.78 (min 65-max 97, SD 09.64). Radiographic signs of osteointegration were detected within the first 6 month after surgery in all cases. Loosening of femoral or tibial components as well as peri-prosthetic infection was not observed in any of the patients during the follow-up. CONCLUSION: The original additive technology for designing and producing patient-specific metaphyseal and diaphyseal cones with different porosity zones for extensive femoral and tibial bone defects in RTKA is precise and clinically effective solution, at least in the short term. It could be a valid alternative to "off-the-shelf" cones or sleeves as well as structural allografts and even mega-prosthesis, but a longer follow-up period is required to assess its medium- and long-term reliability.

International Organism Profile of Periprosthetic Total Hip and Knee Infections.

BACKGROUND: There is scarce literature describing pathogens responsible for periprosthetic joint infections (PJIs) around the world. Therefore, we sought to describe periprosthetic joint infection causative organisms, rates of resistant organisms, and polymicrobial infections at 7 large institutions located in North/South America and Europe. METHODS: We performed a retrospective study of 654 periprosthetic hip (n = 361) and knee (n = 293) infections (January 2006 to October 2019) identified at Cleveland Clinic Ohio/Florida in the United States (US) (n = 159), Hospital Italiano de Buenos Aires in Argentina (n = 99), Hospital Asociación Española in Uruguay (n = 130), Guy's and St Thomas' Hospital in the United Kingdom (UK) (n = 103), HELIOS Klinikum in Germany (n = 59), and Vreden Institute for Orthopedics in St. Petersburg, Russia (n = 104). Analyses were performed for the entire cohort, knees, and hips. Alpha was set at 0.05. RESULTS: Overall, the most frequent organisms identified were Staphylococcus aureus (24.8%) and Staphylococcus epidermidis (21.7%). The incidence of organisms resistant to at least one antibiotic was 58% and there was a significant difference between hips (62.3%) and knees (52.6%) (P = .014). Rates of resistant organisms among countries were 37.7% (US), 66.7% (Argentina), 71.5% (Uruguay), 40.8% (UK), 62.7% (Germany), and 77.9% (Russia) (P < .001). The overall incidence of polymicrobial infections was 9.3% and the rates across nations were 9.4% in the US, 11.1% in Argentina, 4.6% in Uruguay, 4.9% in UK, 11.9% in Germany, and 16.3% in Russia (P = .026). CONCLUSION: In the evaluated institutions, S aureus and S epidermidis accounted for almost 50% of all infections. The US and the UK had the lowest incidence of resistant organisms while Germany and Russia had the highest. The UK and Uruguay had the lowest rates of polymicrobial infections.

Site-Dependent Peculiarities of Calcium Bonds in Bone Tissue.

The relationship of the hierarchical organization of the skeleton with the local electronic and atomic structure of bone is investigated. The Ca 2p photoemission from intact and various arthritis-damaged areas was measured and examined to study site-dependent peculiarities of calcium bonds in subchondral femoral bone. The medial and lateral condyles of the femur resected during total knee arthroplasty were used as samples. The Ca 2p3/2,1/2-1 photoelectron spectra demonstrate the distinct hierarchy-induced deviations of calcium bonds on the proximal side of the samples. It is shown that the apatite calcium bonds dominate in intact area, whereas non-apatite bonds dominate in OA-damaged areas, especially near sclerotic area but not inside it. The site dependence is associated with the interaction of broken collagen molecules with hydroxyapatite nanocrystallites at the cartilage-bone interface. The interplay of biomechanical and biochemical processes is examined, and the restoration of calcium bonds in sclerotic bone is discussed.

Dislocation of modern design rotating hinge total knee arthroplasty : case series and narrative review.

Knee dislocation is an infrequent complication after rotating hinge total knee arthroplasty (RHTKA). The aim of the present study was to describe our experience with dislocating RHTKA in a consecutive prospective large series, its occurrence rate, causative mechanisms and to perform a review of available literature. In total, six dislocations were observed in 303 RHTKA procedures (NexGen RHK, ZimmerBiomet, Warsaw, Indiana, US) at a mean of 10 (range, 2 - 24) months after surgery. This results in a 2% dislocation rate, which is lower than the 3.1% cumulative rate reported earlier in literature. Men and women were distributed equally, with a mean age of 56 years old. The indication for RHTKA among the six dislocations was revision in 4 cases and primary arthroplasty for the other 2 cases. Analysis revealed that the main mechanism of hinge dislocation was forced knee flexion with concomitant extensor mechanism insufficiency (4/6 cases). The second cause was unscrewing of the locking pin (2/6 cases). This is probably caused by the screw home mechanism that results in a counterclockwise torque -and therefore a loosening- effect on locking bolts, specifically in right-sided RHTKA. Obesity probably predisposes to hinge dislocation since 83% of patients in this series were obese (BMI, range 34 to 52). The findings of this study suggest that dislocation of RHTKA is a rare complication that could happen to obsese patients without an adequate extensor mechanism. Level of evidence : IV.

Functional outcome of two-stage reimplantation in patients with periprosthetic joint infection after primary total knee arthroplasty.

INTRODUCTION: Two-stage reimplantation in patients with chronic periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) with the use of either articulating or static antibiotic-loaded spacers during the first step is considered to be the golden standard in orthopaedics. THE AIM OF THE STUDY: The aim of the study was to evaluate the correlation of spacer type with the infection elimination rate as well as functional outcomes after two-staged revision TKA in patients with PJI. MATERIALS AND METHODS: The cohort comprised 161 patients who were treated for PJI after TKA during a period from January 2007 to December 2015. After the exclusion of patients with severe bone defects (AORI 2B or 3), 104 were left for the analysis: 72 patients with articulating and 32 with static spacers. The overall patient mean age was 62 years old (95% CI, 30-84): 73 for females, 31 for males. The outcomes were evaluated after three, six and 12 months using the American Knee Society Score (KSS) and EQ-5D. Only 92 patients were available for observation: 25 with static and 67 with articulating spacers. RESULTS: One year after the surgery, patients with articulating spacers demonstrated significantly higher mean KSS and function scores in comparison to patients with static spacers (90.4, 77.3 and 78.5, 67.8, respectively (p < 0.05)). The range of motion was also significantly better in patients with articulating spacers: 104.9° in comparison to 93.9° (р < 0.0001). The final EQ-5D score was comparable in both groups (0.82, 73.1 in articulating and 0.82, 72.6 in static spacers). CONCLUSION: The two-stage revision TKA for PJI using articulating spacers in comparison to the static ones provides better infection eradication rate as well as functional outcomes and improved quality of life.

Higher physical activity and lower pain levels before surgery predict non-improvement of knee pain 1 year after TKA.

PURPOSE: The purpose of this study was to describe patterns of pain during the first year following total knee arthroplasty (TKA) and evaluate pre- and postoperative factors associated with pain and patient satisfaction at 1 year. It was hypothesized that more severe preoperative pain would be associated with more residual pain and lower patient satisfaction 1 year after surgery. METHODS: A longitudinal cohort study was performed with repeated measures of pain (0-10 numeric rating scale) and evaluation of other self-reported symptoms (Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index, and Fatigue Severity Score), daily functioning (Lawton Instrumental Activities of Daily Living Scale), quality of life (EQ-5D-3L), knee function (KSS Knee and Function Score), perioperative and clinical characteristics (e.g. surgery duration, brand of implant, comorbidities), biochemical parameters (haemoglobin, C-reactive protein, creatinine), and patient satisfaction (20-item scale). Post-surgical improvement was defined as at least a two-point decrease in the patient's rating of pain interference with walking from baseline to 1 year. Hundred patients (mean age 64 ± 8 years and 93% female) consecutively admitted for uncomplicated primary TKA participated, and 79 with complete data were included in this analysis. RESULTS: Pain generally decreased during the first postoperative year, from an average rating of 6 (SD = 3) to 1 (SD = 2). However, 18 of the 79 patients experienced no improvement in pain from baseline to 1 year. Factors associated with non-improvement of pain interference with walking after TKA included lower preoperative ratings of pain interference with walking (p < 0.001) and lower preoperative ratings of average pain (p = 0.004), active or very active levels of preoperative physical activity (p = 0.017), and higher ratings of worst pain on the first three postoperative days (p = 0.028). Pain at 1 year was the only predictor of lower patient satisfaction at 1 year. CONCLUSIONS: Patients with low preoperative pain ratings or high preoperative levels of physical activity are at increased risk of non-improvement in knee pain after TKA. This finding should be taken into consideration when selecting appropriate candidates for TKA surgery. Orthopaedic surgeons should pay particular attention to patients reporting low pain interference with walking and consider other conservative or surgical treatment options before TKA. Effective strategies for detection and treatment of TKA patients with high pain ratings at early follow-up visits also need to be developed. LEVEL OF EVIDENCE: Prognostic study, Level II.

Factors Related to Postoperative Pain Trajectories following Total Knee Arthroplasty: A Longitudinal Study of Patients Admitted to a Russian Orthopaedic Clinic.

This study explores sociodemographic, clinical, and surgical factors in relation to pain trajectories during the first 3 days following total knee arthroplasty (TKA). 100 patients (mean age 63.5 ± 7.8 years and 93% female) consecutively admitted for uncomplicated primary TKA were prospectively included. Postoperative pain was assessed using pain diaries. Measures of preoperative pain, symptoms, daily functioning, quality of life, comorbidities, knee function, perioperative characteristics, and physical/biochemical parameters were also evaluated. All pain ratings decreased in the three days following surgery (p < .001) as well as the reported number of daily hours in moderate/severe pain (p < .001). Women reported more pain than men (p = .009). Pain trajectories did not differ by education, employment, cohabitation, or any patient clinical and biochemical characteristics but were significantly related to preoperative anxiety (p = .029). Patients reporting moderate/severe pain prior to surgery also reported more hours in moderate/severe pain on days 0-3 postoperatively (p = .029). Patients with surgeries longer than 90 min reported more hours of moderate/severe pain compared with patients who had shorter surgeries (p = .008), and similar results were observed for ratings of pain with activity (p = .012). In this sample, only female gender, higher levels of preoperative pain and anxiety, and longer surgical duration were associated with increased pain after TKA.

Computer navigation helps achieving appropriate gap balancing and restoration of alignment in total knee arthroplasty for fixed valgus knee osteoarthritis irrespective of the surgical approach.

The aim of this study was to describe the deformity of both bone and soft tissues in valgus knees and attempt, with the help of computer-assisted total knee arthroplasty (CAS-TKA), to answer the question whether a medial or lateral approach should be used in a fixed deformity. This was a prospective study of 52 consecutive patients with valgus knee osteoarthritis (OA) on who CAS-TKA was performed between 2008 and 2012. Only patients (N = 42) with valgus deformity Krackow type II and III were included for detailed analysis: 17 were operated utilizing a medial and 25 using a lateral approach. Computer navigation was used to perform quantitative control of alignment and gap changes in the medial and lateral knee compartment after each step of the release. Radiological alignment as well as functional results with Knee Society and WOMAC scores were evaluated after a mean (SD) of 23 (5) months in all patients. Twenty-eight different combinations of pathological changes of bone and soft-tissues were described in the 52 patients making the identification of a typical pathological pattern for valgus deformity impossible. In 60% of patients, irrespective from the approach, the valgus deformity was reduced after release of the ilio-tibial tract. No significant difference between both groups was observed in the extent of releases, gap balancing, surgical time, implants constraint, leg alignment and mid-term functional outcomes. None of the included patients were revised for any reason.