AI-based hip prosthesis failure prediction through evolutional radiological indices.

INTRODUCTION: This study aimed to develop artificial intelligence models for predicting hip implant failure from radiological features. Analyzing the evolution of the periprosthetic bone and implant's position throughout the entire follow-up period has shown the potential to be more relevant in outcome prediction than simply considering the latest radiographic images. Thus, we investigated an AI-based model employing a small set of evolutional parameters derived from conventional radiological features to predict hip prosthesis failure. MATERIALS AND METHODS: One hundred sixty-nine radiological features were annotated from historical anteroposterior and lateral radiographs for 162 total hip arthroplasty patients, 32 of which later underwent implant failure. Linear regression on each patient's chronologically sorted radiological features was employed to derive 169 corresponding evolutional parameters per image. Three sets of machine learning predictors were developed: one employing the original features (standard model), one the evolutional ones (evolutional model), and the last their union (hybrid model). Each set included a model employing all the available features (full model) and a model employing the few most predictive ones according to Gini importance (minimal model). RESULTS: The evolutional and hybrid predictors resulted highly effective (area under the ROC curve (AUC) of full models = 0.94), outperforming the standard one, whose AUC was only 0.82. The minimal hybrid model, employing just four features, three of which evolutional, scored an AUC of 0.95, proving even more accurate than the full one, exploiting 173 features. This tool could be shaped to be either highly specific (sensitivity: 80%, specificity: 98.6%) or highly sensitive (sensitivity: 90%, specificity: 92.4%). CONCLUSION: The proposed predictor may represent a highly sensitive screening tool for clinicians, capable to predict THA failure with an advance between a few months and more than a year through only four radiological parameters, considering either their value at the latest visit or their evolution through time.

Clinical and radiological outcomes of an uncemented metaphyseal short stem at minimum 10 years of follow-up: a prospective observational study.

PURPOSE: There is growing interest around short stems as they provide a less invasive approach for total hip arthroplasty preserving bone stock for a possible revision surgery if required. The main purpose of this work was to assess the long-term performance of an uncemented metaphyseal short stem in terms of survival rate and in addition its clinical and radiological outcomes. MATERIALS AND METHODS: From January to December 2010, we prospectively enrolled all consecutive patients undergoing primary total hip arthroplasty with an uncemented metaphyseal short stem in our institution with a minimum follow-up of 10 years. The radiographic features investigated were the varus-valgus stem orientation, areas of osteolysis and radiolucencies, stress shielding, and heterotopic calcifications. The clinical outcomes were measured using the HHS. RESULTS: A total of 163 patients (172 hips) were finally included and the measured survival rate at 10 years was 99.6%. The average HHS increased from 55.0 preoperatively to 97.8 at the last follow-up (p < 0.0001). Among them, 137 patients (164 hips) were also available for radiographic assessment. Mild varus malalignment was observed in 40% of cases and remained stable in the serial X-rays and was not associated with step loosening. Mild stress shielding was observed around 13 stems (9%) and moderate only around 3 implants. CONCLUSION: In conclusion, the uncemented metaphyseal short stems showed excellent survival and clinical results at 10 years and at a radiographical level very low stress shielding was observed; moreover, besides the high frequency of varus alignment the implanted stems was not associated with revision surgery or with worse clinical outcomes.

A new classification to characterize and predict treatment of acetabular bone defects.

BACKGROUND: The increasing amount of revision surgeries in total hip arthroplasty (THA) represents a burden for orthopedic surgeons given the complexity and unpredictability of this kind of surgery. The aim of the current study was to develop a new radiographic classification of acetabular bone defects stratify the severity of the lesion and to suggest the surgical strategy to address it. METHODS: Radiographs of 151 consecutive patients who underwent acetabular revision surgery in our institution were collected to develop a new classification that groups the acetabular bone defects in three zones (A, B and C). The performance to predict treatment and inter- and intra-rater agreement were evaluated. RESULTS: The ability of the newly proposed classification to predict treatment was 87.3% (k weighted: 0.65). The inter-rater reliability was 90.1% (k: 0.81), and the intra-rater reliability between the two sets of evaluations performed by the observer at 1-month distance was 97.5% (k: 0.94). CONCLUSIONS: The newly proposed classification was able to characterize the extent of acetabular bone defects and predict pre-operatively the appropriate surgical treatment strategy in 87.3% of cases. It showed a strong agreement among raters and an almost perfect agreement among different measurements at 1 month distance. This new tool could be used in the preoperative assessment to drive the use of secondary level image examinations and the type of surgical management.

Interaction of Bacteria, Immune Cells, and Surface Topography in Periprosthetic Joint Infections.

The incidence of periprosthetic joint infections (PJIs) is ~2% of total procedures and it is expected to rise due to an ageing population. Despite the large burden PJI has on both the individual and society, the immune response to the most commonly isolated pathogens, i.e., Staphylococcus aureus and Staphylococcus epidermidis, remains incompletely understood. In this work, we integrate the analysis of synovial fluids from patients undergoing hip and knee replacement surgery with in-vitro experimental data obtained using a newly developed platform, mimicking the environment of periprosthetic implants. We found that the presence of an implant, even in patients undergoing aseptic revisions, is sufficient to induce an immune response, which is significantly different between septic and aseptic revisions. This difference is confirmed by the presence of pro- and anti-inflammatory cytokines in synovial fluids. Moreover, we discovered that the immune response is also dependent on the type of bacteria and the topography of the implant surface. While S. epidermidis seems to be able to hide better from the attack of the immune system when cultured on rough surfaces (indicative of uncemented prostheses), S. aureus reacts differently depending on the contact surface it is exposed to. The experiments we performed in-vitro also showed a higher biofilm formation on rough surfaces compared to flat ones for both species, suggesting that the topography of the implant could influence both biofilm formation and the consequent immune response.

Action Observation and Motor Imagery administered the day before surgery enhance functional recovery in patients after total hip arthroplasty: A randomized controlled trial.

OBJECTIVE: To investigate the effects of Action Observation and Motor Imagery administered the day before surgery on functional recovery in patients after total hip arthroplasty. DESIGN: Randomised controlled trial. SETTING: Humanitas Clinical and Research Center, Milan, Italy. PARTICIPANTS: Eighty inpatients with end-stage hip osteoarthritis undergoing total hip arthroplasty. INTERVENTIONS: All patients followed a standardized postoperative rehabilitation program. Experimental group (AO + MI) performed two 12-minute Action Observation and Motor Imagery sessions on the preoperative day, whereas control group underwent usual care consisting of education without any additional preoperative activity. OUTCOME MEASURES: A blinded physiotherapist assessed participants for functional mobility (Timed Up and Go - TUG) (primary outcome), maximum walking speed (10-Meter Walk Test - 10MWT), pain (Numeric Pain Rating Scale - NPRS) and fear of movement (Tampa Scale of Kinesiophobia - TSK) the day before and at four days after surgery. RESULTS: No between-group differences were found at baseline. Although TUG and 10MWT worsened in both groups (p < 0.001), better TUG was found for AO + MI group at four days (mean difference -5.8 s, 95% confidence interval from -11.3 to -0.3 s, p = 0.039). NPRS (p < 0.001) and TSK (p = 0.036 for AO + MI group, p = 0.003 for control group) improved after surgery without between-group differences. CONCLUSIONS: Patients undergoing Action Observation and Motor Imagery on the day before surgery showed less functional decline than control group in the first days after total hip arthroplasty. This intervention may contribute to a safer discharge with higher functional abilities in patients hospitalized for total hip arthroplasty.

Incidence and predictors of blood transfusions in one-stage bilateral total hip arthroplasty: a single center prospective cohort study.

INTRODUCTION: The safety of performing one-stage bilateral total hip arthroplasty (THA) remains controversial among the orthopedic community. The aim of the present study was to determine the incidence and predictors of blood transfusions in one-stage bilateral THA performed in a high-volume single center. PATIENTS AND METHODS: Patients undergoing one-stage bilateral THA between 2015 and 2017 were included. The following data were collected from the hospital medical records: age, body mass index (BMI), American Society of Anaesthesiologists (ASA) score, smoking habit, comorbidities, preoperative serum creatinine, serum iron, ferritin, C-reactive protein (CRP), and hemoglobin (Hb). The Hb levels at postoperative day 1 and 3 were also collected. RESULTS: A total of 367 patients with a mean age of 56.1 years (range, 32-79) were included. Forty-eight (13%) patients were transfused with a mean number of 1.6 blood units per patient. In non-transfused patients, the average Hb drop was 3.6 (SD ± 1) g/dL and 4.9 g/dL (SD ± 1.3) at postoperative day 1 and day 3, respectively. The average preoperative Hb level was 14.64 (SD ± 1.21) g/dL. In the univariate logistic regression, the following variables were predictive factors for transfusions: male gender (OR 0.447; P = 0.01), preoperative hemoglobin level (OR 0.622; P = 0.001), preoperative ferritin level (OR 0.995; P = 0.016), BMI (OR 0.837; P = 0.001), cardiopathy (OR 3.534; P = 0.046), preoperative anaemia (OR 10.54; P = 0.011). In the multivariate logistic regression only preoperative hemoglobin level (OR 0.666; P = 0.01), and BMI (OR 0.868; P = 0.007) were statistically significant. CONCLUSIONS: The incidence of blood transfusions after one-stage bilateral THA is low in non-anemic patients operated on at a high-volume arthroplasty center. The main predictors of blood transfusions are preoperative Hb level and BMI.

Conversion of Fused Hip to Total Hip Arthroplasty: Long-Term Clinical and Radiological Outcomes.

BACKGROUND: Despite promising results at the mid-term followup, several aspects of conversion of the fused hip to total hip arthroplasty (THA) remain controversial. The aim of this study was to evaluate clinical and radiological outcomes with a minimum 5-year followup in patients who underwent conversion of the fused hip to THA. METHODS: Fifty-seven patients (59 hips) were evaluated. The Harris Hip Score (HHS), range of motion (ROM), and the Visual Analogue Scale (VAS) were used to assess hip function and low back pain. Subjective satisfaction with surgery and the presence of the Trendelenburg sign was also evaluated. Radiological assessment was performed pre- and postoperatively to evaluate loosening and heterotopic ossification (HO). RESULTS: After a mean followup of 13.0 ± 6.2 years, HHS and VAS significantly improved from 46.0 ± 16.7 to 80.8 ± 18.8 and from 4.4 ± 1.5 to 2.1 ± 1.4 (both P < .001), respectively. Twenty-three patients (40.4%) had a positive Trendelenburg sign, and HOs were found in 29 cases (49.1%). An overall 29.8% complication rate was noted. Smoking habits and rheumatoid arthritis were predictive of Trendelenburg sign (P = .046 and P = .038, respectively). Implant survival rate as the end point was 98.7 ± 1.3% at 5 years, 92.4 ± 3.3% at 10 years, 82.1 ± 5.7% at 15 years, and 73.4 ± 8.0% at 20 and 25 years. A worse cumulative implant survival rate was noted in patients who underwent previous hip surgery, defined as any hip operation before fusion (P = .005). CONCLUSION: Conversion of the fused hip to hip arthroplasty provides high levels of hip functionality and satisfaction with surgery at long-term followup. An implant survival rate higher than 70% can be expected 25 years postoperatively.

Outcomes of patients with unexpected diagnosis of infection at total hip or total knee arthroplasty revisions.

PURPOSE: The pre-operative differential diagnosis between periprosthetic joint infections (PJIs) and aseptic failure is challenging particularly in low virulence and biofilm-related infections. This study aimed to assess the incidence and survival of patients with unexpected PJIs in a presumed aseptic revision of total hip (THA) and knee (TKA) arthroplasties. METHODS: A retrospective analysis of a prospective cohort of patients was performed with 295 patients undergoing THA (n = 241) or TKA (n = 54) revision for presumed aseptic causes. Patients were diagnosed with unexpected PJI taking into account leukocyte count in the synovial fluid, sonicate, synovial culture, and tissue cultures of samples collected during surgery. The primary endpoint was the infection-free implant survival rate at theone year follow-up. RESULTS: The unexpected PJIs were 60 out of 295 (20.3%), whereas 235 (79.7%) were aseptic revisions. In the unexpected PJI group, 6 (11.1%) patients underwent knee revision and 54 (22.4%) hip revision. At the one year follow-up, one patient (1.6%) in the unexpected PJI group and 3 (1.3%) in the aseptic group (p = 1.0) failed for infection. The infection-free implant survival rate at the one year follow-up was 98.3% (C.I. 95%, 94.9-99.9%) for the unexpected PJI group and 98.7% (C.I. 95%, 97.3-99.9%) (p = 0.82) for the aseptic group. CONCLUSION: The incidence of unexpected PJIs in a presumed aseptic revision of THAs and TKAs has been previously underestimated. The infection-free implant survival rate at the one year follow-up in patients with unexpected PJIs was not significantly lower compared with patients undergoing aseptic revision.

Total Hip Arthroplasty With a Monoblock Conical Stem in Dysplastic Hips: A 20-Year Follow-Up Study.

BACKGROUND: Total hip arthroplasty in patients with hip dysplasia is challenging as a result of complex anatomic deformities in the hip. The aim of the study was to evaluate the survivorship, the clinical and radiographic outcomes of cementless Wagner Cone stem in patients with dysplastic hip. METHODS: This retrospective study reports on 102 patients (135 hips) who have undergone total hip arthroplasty between 1993 and 1997. The mean age of patients was 51 years (range, 21-73). Minimum follow-up was 20 years. According to the Crowe classification, 38 hips presented dysplasia of grade I, 41 of grade II, 37 of grade III, and 19 of grade IV. RESULTS: Kaplan-Meier survivorship for aseptic loosening was 97% (95% confidence interval, 94.4-99.6) at 20 years. The average Harris hip score increased from 43.4 points (range, 22-51) to 86.4 points (range, 39-100) (P < .0001) and average Merle d'Aubignè score increased from 8.4 (range, 4-13) to 15 (range, 5-18) (P < .0001); at the last follow-up, average University of California at Los Angeles activity score and visual analog score were 4.53 (range, 1-9) and 1.25 (range, 0-6), respectively; 17% of heterotopic ossification and 19.2% of radiolucency lines around the stem were reported. CONCLUSION: Monoblock Wagner Cone stem is a reliable option in dysplastic hip with an excellent survivorship and good clinical and radiographic outcome in the long term.

Outcome of short versus conventional stem for total hip arthroplasty in the femur with a high cortical index: a five year follow-up prospective multicentre comparative study.

BACKGROUND: The uncemented total hip arthroplasty (THA) has become the choice for many hip surgeons. Although conventional uncemented femoral components have a proven track record, there remain concerns about the rate of thigh pain, proximal stress shielding, and consequent loss of bone stock at revision surgery. METHODS: Inclusion criteria were the following: patients between 50 and 85 years old undergoing primary THA with implant of short (group 1) or conventional (group 2) femoral stem and with femoral shape type A, according to Dorr classification. Clinical follow-up was registered using OHS, HHS, and Womac scores. The radiographic scans were evaluated in order to compare component positioning and bone remodeling at five year follow-up. RESULTS: We included in the analysis 60 subjects in group 1 and 67 in group 2. No differences were registered between the groups comparing demographic and operative data. One case in group 1 (1.7%) and three cases in group 2 (4.5%) reported an intra-operative fracture. There was a significant improvement in the functional scores in both groups with no significant difference at final follow-up. The incidence of reported thigh pain at follow-up was 14.9% in group 2 and 3.3% in group 1 (p = 0.033). Radiographic analysis documented a difference in terms of stress shielding and thinning of medial and lateral cortex in favour of group 1. Moreover, patients of group 1 showed a higher varus angle at six month follow-up. CONCLUSION: In patients with high cortical index, a short stem shows better clinical and radiological outcomes at five year follow-up.