Gender-based differences exist in the functional knee phenotypes classification of the osteoarthritic knee.

PURPOSE: To identify gender differences in (1) the coronal alignment of functional knee phenotypes and (2) the JLCA (joint line convergence angle) in relation to the phenotype classification. METHODS: This study is a retrospective data analysis, including 12,099 osteoarthritic knee computed tomography (5025 male, 7074 female) analysed by Medacta software for hip-knee-ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA) and JLCA. The data were grouped into genders and combined according to the Functional Knee Phenotypes Classification. RESULTS: Out of 127 phenotypes for males and 131 for females, 17 common phenotypes were reported. The commonest four were similar for both genders with VARHKA177° NEUFMA93° NEUTMA87° (9.8% males, 9.50% females), followed by VARHKA174° NEUFMA93°VARTMA84° (7.1%) and VARHKA174°VARFMA90° NEUTMA87° (7.0%) for males and VARHKA174° NEUFMA93° NEUTMA87° (6.1%), VARHKA174° NEUFMA93°VARTMA84° (5.1%) for females. The commonest FMA and TMA (91.5° to 94.5° and 85.5° to 88.5°, respectively) were the same for both genders, however, the rest of the male population observed greater femoral varus than the female population (p < 0.001). JLCA values ranged from -28.4° to 8.2° in the overall study population. Males and females had a mean JLCA of -2.96° (±2.6° SD) and -2.66° (±2.8°7 SD), respectively, p < 0.001. CONCLUSIONS: Gender differences exist within the osteoarthritic knee phenotype. The male varus phenotype is influenced by FMA, while TMA values are similar across genders. JLCA variations show similarities to both TMA and FMA, suggesting JLCA is influenced by bone morphology more than by gender. These differences inform surgical decision-making for the personalised approach to the primary TKA. LEVEL OF EVIDENCE: Level III.

Only 26% of Native Knees Show an Identical Coronal Functional Knee Phenotype in the Contralateral Knee.

BACKGROUND: A comprehensive exploration evaluating left-to-right knee symmetry across all anatomical planes utilizing three-dimensional (3D) scans stands absent from the existing body of research. Therefore, the primary objectives of this investigation involved examining potential differences and resemblances in alignment and structure between left and right non-osteoarthritic (native) knees in various planes (coronal, sagittal, and axial) using three-dimensional single-photon emission computed tomography/computed tomography (SPECT/CT) images. METHODS: A total of 282 native knees from 141 patients were retrospectively gathered from the hospital's records. Patients, aged between 16 and 45, who underwent Tc99m-methyl diphosphonate SPECT/CT scans for both knees, adhering to the Imperial Knee Protocol, were included. A statistical analysis was conducted, including 23 knee morphometric parameters, comparing left and right knees, and classifying them based on functional knee phenotypes across the coronal, sagittal, and axial planes. RESULTS: Regarding the functional coronal knee phenotype, 26% of patients (n = 37) exhibited identical phenotypes in both knees (p < 0.001). Significant correlated similarities between the left and right knees were observed in the coronal plane (Pearson's r = 0.76, 0.68, 0.76, 0.76, p < 0.001) and in several morphometric measures in the sagittal plane (Pearson's r = 0.92, 0.72, 0.64, p < 0.001). Moderately correlated similarities were noted in the axial plane (Pearson's r = 0.43, 0.44, 0.43, p < 0.001). CONCLUSIONS: Only 26% of native knees exhibit an identical coronal phenotype in their contralateral knee, whereas 67% have the adjacent coronal phenotype. Strongly correlated resemblances were established across various left and right knee morphometric parameters in the coronal, sagittal, and axial planes. These findings could enhance decisions in procedures like total knee arthroplasties or osteotomies, where alignment is key to outcomes, and reveal a potential for future artificial intelligence-driven models to improve our understanding and improve personalized treatment strategies for knee osteoarthritis.

Definition of normal, neutral, deviant and aberrant coronal knee alignment for total knee arthroplasty.

PURPOSE: One of the most pertinent questions in total knee arthroplasty (TKA) is: what could be considered normal coronal alignment? This study aims to define normal, neutral, deviant and aberrant coronal alignment using large data from a computed tomography (CT)-scan database and previously published phenotypes. METHODS: Coronal alignment parameters from 11,191 knee osteoarthritis (OA) patients were measured based on three dimensional reconstructed CT data using a validated planning software. Based on these measurements, patients' coronal alignment was phenotyped according to the functional knee phenotype concept. These phenotypes represent an alignment variation of the overall hip knee ankle angle (HKA), femoral mechanical angle (FMA) and tibial mechanical angle (TMA). Each phenotype is defined by a specific mean and covers a range of ±1.5° from this mean. Coronal alignment is classified as normal, neutral, deviant and aberrant based on distribution frequency. Mean values and distribution among the phenotypes are presented and compared between two populations (OA patients in this study and non-OA patients from a previously published study). RESULTS: The arithmetic HKA (aHKA), combined normalised data of FMA and TMA, showed that 36.0% of knees were neutral within ±1 SD from the mean in both angles, 44.3% had either a TMA or a FMA within ±1-2 SD (normally aligned), 15.3% of the patients were deviant within ±2-3 SD and only 4.4% of them had an aberrant alignment (±3-4 SD in 3.4% and >4 SD in 1.0% of the patients respectively). However, combining the normalised data of HKA, FMA and TMA, 15.4% of patients were neutral in all three angles, 39.7% were at least normal, 27.7% had at least one deviant angle and 17.2% had at least one aberrant angle. For HKA, the males exhibited 1° varus and females were neutral. For FMA, the females exhibited 0.7° more valgus in mean than males and grew 1.8° per category (males grew 2.1° per category). For TMA, the males exhibited 1.3° more varus than females and both grew 2.3° and 2.4° (females) per category. Normal coronal alignment was 179.2° ± 2.8-5.6° (males) and 180.5 > ± 2.8-5.6° (females) for HKA, 93.1 > ± 2.1-4.2° (males) and 93.8 > ± 1.8-3.6° (females) for FMA and 86.7 > ± 2.3-4.6° (males) and 88 > ± 2.4-4.8° (females) for TMA. This means HKA 6.4 varus or 4.8° valgus (males) or 5.1° varus to 6.1° valgus was considered normal. For FMA HKA 1.1 varus or 7.3° valgus (males) or 0.2° valgus to 7.4° valgus was considered normal. For TMA HKA 7.9 varus or 1.3° valgus (males) or 6.8° varus to 2.8° valgus was considered normal. Aberrant coronal alignment started from 179.2° ± 8.4° (males) and 180.5 > ± 8.4° (females) for HKA, 93.1 > ± 6.3° (males) 93.8 > ± 5.4° (females) for FMA and 86.7 > ± 6.9° (males) and 88 > ± 7.2° (females) for TMA. This means HKA > 9.2° varus or 7.6° valgus (males) or 7.9° varus to 8.9° valgus was considered aberrant. CONCLUSION: Definitions of neutrality, normality, deviance as well as aberrance for coronal alignment in TKA were proposed in this study according to their distribution frequencies. This can be seen as an important first step towards a safe transition from the conventional one-size-fits-all to a more personalised coronal alignment target. There should be further definitions combining bony alignment, joint surfaces' morphology, soft tissue laxities and joint kinematics. LEVEL OF EVIDENCE: III.

Effectiveness of manual lymphatic drainage and intermittent pneumatic compression in lymphedema maintenance therapy.

Background: To compare the effectiveness of intermittent pneumatic compression (IPC) and/or manual lymphatic drainage (MLD) associated to compression stockings in the maintenance treatment of lymphedema. Patients and methods: Patients in the maintenance phase of lymphedema therapy with MLD and compression since more than a year with stable values for weight and circumferences of ankle and calf were asked to participate in a study: Compression had to be worn daily, (1) 4 weeks IPC+MLD, (2) 4 weeks MLD alone, (3) 4 Weeks IPC alone (Order 1 and 3 was randomized). At the beginning and after each 4 weeks, circumference measurements (by hand and by machine: BT600®, Bauerfeind) were documented, pain and discomfort were assessed, and quality-of-life questionnaires were completed. Results: Of 20 participants, 18 (14 female, 4 male), mean age 59.6 years (48-89) could be evaluated. 11 subjects had bilateral, 7 unilateral, 5 primary, 13 secondary lymphedema since 2-20 years (mean 7.7), the subjects had received MLD and compression for 2-14 years (mean 6.4), 1-3 times per week (mean 1.5). The BMI ranged between 21 and 47 (mean 33.7). No differences between any phases were found for: Calf and thigh volume, circumference of calf. Only the ankle circumference was significant less (-0.22 cm) when using "both" (IPC+MLD). Compared to before the study, quality of life was better in all three phases, but with a significantly higher improvement in the phases with IPC than in the phases without. Conclusions: There were no differences in objective measurement between MLD alone, IPC alone or both, excepting the minimal significant difference in ankle circumference after IPC+MLD. QOL favored IPC application. Considering the economic consequences of these results, a change of maintenance therapy with MLD weekly over years in favor of permanent care with IPC and few appointments of MLD per year should be considered and further investigated.

Use of the forgotten joint score (FJS)-12 to evaluate knee awareness after quadriceps tendon reconstruction.

BACKGROUND: Quadriceps tendon rupture (QTR) is a severe injury of the knee extensor apparatus. The study aims to validate the use of forgotten joint score (FJS-12) for functional outcome assessing after surgical treatment of QTR. METHODS: Fifty-seven patients who underwent surgery for QTR with transosseous suture reconstruction in a single orthopaedic surgery and traumatology center between 2015 and 2020 were eligible for enrolment in this retrospective case series. The demographic data and other pre-operative details such as age, gender, comorbidities and medication use also were extracted from the medical records. Patient reported outcome measures (PROMs) were gathered in the form of Western Ontario and McMaster Universities Arthritis Index Score (WOMAC), Tegner Activity Score (TAS), Lysholm Score and FJS-12 at a mean follow-up time of 49.84 months ± 20.64 months. The FJS-12 was validated by correlation with WOMAC, TAS and Lysholm Score. RESULTS: The mean age of all patients were 69.2 ± 13.6 years with 51 (89.5%) males and 6 (10.5%) females. The mean time from injury to surgery was 3.39 ± 5.46 days. All patients reported satisfactory functional outcomes after surgery on FJS-12, WOMAC and Lysholm scores, except the TAS, which decreased slightly from pre-operative level. There was a high negative correlation between WOMAC and FJS-12, but moderate positive correlations between FJS-12 and TAS and Lysholm scores. The Cronbach's alpha value was 0.96 for 12 items in FJS-12. CONCLUSION: This study has found that FJS-12 is a reliable and easy to assess tool for functional outcomes after QTR reconstruction. It has shown moderate to strong correlation with other commonly used outcome measures (WOMAC, TAS and Lysholm).

Comparative retrieval analysis of a novel anatomic tibial tray backside: alterations in tibial component design and surface coating can increase cement adhesions and surface roughness.

BACKGROUND: With the Persona® knee system a novel anatomic total knee design was developed, which has no pre-coating, whereas the predecessor knee system is pre-coated with polymethylmethacrylate (PMMA). Joint registry data have shown no decrease in risk of aseptic revision of PMMA pre-coated tibial components compared with non-pre-coated implants. The aim of this retrieval study was to compare the amount of cement adhesions, geometry and surface features between the two knee designs and to correlate them with the underlying reason for revision surgery. METHODS: Retrieval analysis was performed of 15 NexGen® and 8 Persona® fixed-bearing knee implants from the same manufacturer retrieved from two knee revision centres. A photogrammetric method was used to grade the amount of cement attached to the tibial tray backside. The geometry and dimensions of the tibial trays, tray projections and peripheral lips were measured using digital callipers and compared between the two different designs. To measure the surface roughness on the backside of the tibial tray, a contact profilometer was used. To investigate differences between the two designs statistical analyses (t-test) were performed. RESULTS: All Persona® trays showed evidence of cement adhesion with a % area of 75.4%; half of the NexGen® trays had cement adhesions, with a mean value of 20%. There was a significant difference in the percentage of area covered by cement between the two designs (p < 0.001). Results from the contact profilometer revealed that Persona® and NexGen® tray backsides showed a similar lateral (1.36 µm and 1.10 µm) and medial (1.39 µm and 1.12 µm) mean surface roughness with significant differentiation (p < 0.05) of the lateral and medial roughness values between the two designs. Persona® stems showed a significantly higher mean surface roughness (1.26) compared to NexGen® stems (0.89; p < 0.05). CONCLUSION: The novel anatomic knee system showed significantly more cements adhesions and a higher surface roughness which was most likely attributed to the most obvious design and coating alteration of the tibial tray. This study provides first retrieval findings of a novel TKA design recently introduced to the market.

Stress Radiographs in the Posterior Drawer Position at 90° Flexion Should Be Used for the Evaluation of the PCL in CR TKA with Flexion Instability.

The purpose of this study was to define a cut-off value for the posterior drawer position in stress radiography that confirms an insufficiency of the posterior cruciate ligament (PCL) in cruciate-retaining (CR) total knee arthroplasty (TKA). In this retrospective study, 20 symptomatic patients with flexion instability and suspected PCL insufficiency in CR TKA were included. Asymptomatic patients served as an age- and sex-matched control group. All of the patients had undergone stress radiography, and the posterior translation was measured in a posterior drawer position at 30° and 90° flexion. The two groups were compared using t-tests and chi-square tests. The stress radiographs showed significantly more posterior translation in the symptomatic group (p < 0.01). Stress radiographs at 90° flexion more effectively discriminated between the patients with and without PCL insufficiency compared with those carried out at 30° flexion. Sensitivity and specificity testing revealed the best sensitivity (90.5%) and the best specificity (94.7%) at 90° posterior drawer radiographs at a cut-off value of 10 mm. Stress radiographs including the posterior drawer position at 90° flexion should be part of the diagnostic algorithm in patients with suspected flexion instability. A posterior translation of more than 10 mm in CR TKA strongly indicates an insufficiency of the PCL.

Ethnical Differences in Knee Phenotypes Indicate the Need for a More Individualized Approach in Knee Arthroplasty: A Comparison of 80 Asian Knees with 308 Caucasian Knees.

The purpose of this study was to determine the distribution of functional knee phenotypes in a non-osteoarthritic Asian population. The Stryker Orthopaedic Modeling and Analytics (SOMA) database was searched for CT scans of the lower limb meeting the following inclusion criteria: patient age at time of image >18 and <46 years, no signs of fractures and/or previous surgery and/or degenerative changes, Asian ethnicity. A total of 80 CT scans of 40 patients were included (24 males, 16 females). The hip-knee-ankle angle (HKA), femoral mechanical angle (FMA) and tibial mechanical angle (TMA) were measured. Based on these measurements, each limb was phenotyped according to the previously introduced functional knee phenotype concept. All angles and phenotypes of the present study were compared with previously published data of a non-osteoarthritic Caucasian population (308 legs of 160 patients, 102 males, 58 females). Asian knees had a significantly lower TMA (both genders p < 0.001) but a higher FMA (males p < 0.05, females p < 0.001) than Caucasian knees but showed no difference in the HKA. Asian knees differed significantly with regard to femoral and tibial phenotypes (p < 0.01), but not with regard to limb phenotypes. The high variability of all coronal alignment parameters highlights the importance of a detailed analysis prior to TKA. Ethnical differences underline the need for a more individualized approach in TKA.

Detailed information gain and therapeutic impact of whole body computed tomography supplementary to conventional radiological diagnostics in blunt trauma emergency treatment: a consecutive trauma centre evaluation.

PURPOSE: The indication of whole body computed tomography (WBCT) in the emergency treatment of trauma is still under debate. We were interested in the detailed information gain obtained from WBCT following standardized conventional imaging (CI). METHODS: Prospective study including all emergency trauma centre patients examined by CI (focused assessment of sonography in trauma, chest and pelvic X-ray) followed by WBCT from 2011 to 2017. Radiology reports were compared per patient for defined body regions for number and severity of injuries (Abbreviated Injury Scale, AIS; Injury Severity Score, ISS), incidental findings and treatment consequences (Wilcoxon signed rank test, Spearman rho, Chi-square). RESULTS: 1271 trauma patients (ISS 11.3) were included in this study. WBCT detected more injury findings than CI in the equivalent body regions (1.8 vs. 0.6; p < 0.001). In 44.4% of cases at least one finding was missed by CI alone. Compared to WBCT, injury severity of specified body regions was underestimated by CI on average by an AIS of 1.9 (p < 0.001). In 22.0% of cases injury severity increased by an AIS ≥ 2 following WBCT. In 16.8% of patients additional injury findings resulted in a change of treatment (number needed to profit, NNP = 6 patients): NNP decreased from 25 for patients with an ISS < 7 up to nearly 2 for patients with an ISS > 25 at final evaluation, thereby demonstrating a significant improvement in the NNP with increasing ISS (rho = 0.33, p < 0.001). Moreover, WBCT in 88.4% of patients identified ≥ 1 incidental finding (mean 3.4) vs. 28.9% by CI only (p < 0.001). Overall, WBCT had treatment consequences in 31.9% of cases (NNP = 3.1). CONCLUSIONS: The application of WBCT in addition to CI in the emergency treatment of trauma had therapy consequences for almost every third patient. On the other hand, WBCT appeared not to be indicated (ISS < 8) in at least 2/5 of patients.

Osteoarthritic and non-osteoarthritic patients show comparable coronal knee joint line orientations in a cross-sectional study based on 3D reconstructed CT images.

PURPOSE: Recently introduced total knee arthroplasty (TKA) alignment strategies aim to restore the pre-arthritic alignment of an individual patient. The native alignment of a patient can only be restored with detailed knowledge about the native and osteoarthritic alignment as well as differences between them. The first aim of this study was to assess the alignment of a large series of osteoarthritic (OA) knees and investigate whether femoral and tibial joint lines vary within patients with the same overall lower limb alignment. The secondary aim was to compare the alignment of OA patients to the previously published data of non-OA patients. This information could be useful for surgeons considering implementing one of the new alignment concepts. MATERIAL: Coronal alignment parameters of 2692 knee OA patients were measured based on 3D reconstructed CT data using a validated planning software (Knee-PLAN®, Symbios, Yverdon les Bains, Switzerland). Based on these measurements, patients' coronal alignment was phenotyped according to the functional knee phenotype concept. These phenotypes represent an alignment variation of either the overall alignment, the femoral joint line orientation or the tibial joint line orientation. Each phenotype is defined by a specific mean and covers a range of ± 1.5° from this mean. Mean values and distribution among the phenotypes are presented and compared between two populations (OA patients of this study and non-OA patients of a previously published study) as well as between HKA subgroups (varus, valgus and neutral) using t tests and Chi-square tests (p < 0.05). RESULTS: Femoral and tibial joint lines varied within patients with the same overall lower limb alignment. A total of 162 functional knee phenotypes were found (119 males, 136 females and 94 mutual phenotypes). Mean values differed between the OA and non-OA population, but differences were small (< 2°) except for the overall alignment (e.g. HKA). The distribution of OA and non-OA patients among the phenotypes differed significantly, especially among the limb phenotypes. CONCLUSION: Differences between OA and non-OA knees are small regarding coronal femoral and tibial joint line orientation. Femoral and tibial joint line orientation of osteoarthritic patients can, therefore, be used to estimate their native coronal alignment and plan an individualized knee alignment. LEVEL OF CLINICAL EVIDENCE: III.

Diagnostics of infrapatellar saphenous neuralgia-a reversible cause of chronic anteromedial pain following knee surgery.

OBJECTIVES: To evaluate the impact of diagnostic nerve block and ultrasound findings on therapeutic choices and predict the outcome after concomitant surgery in patients with suspected neuropathy of the infrapatellar branch of the saphenous nerve (IPBSN). METHODS: Fifty-five patients following knee surgery with suspicion of IPBSN neuralgia were retrospectively included. Ultrasound reports were assessed for neuroma and postsurgical scarring (yes/no). Responders and non-responders were assigned following anesthetic injection of the IPBSN. The type of procedure (neurectomy/interventional pain procedure/other than nerve-associated therapy) and pain score at initial follow-up were recorded and patients were assigned as positive (full pain relief) or negative (partial/no pain relief) to therapeutic nerve treatment. Factors associated with a relevant visual analog scale (VAS) reduction were assessed using uni- and multivariate logistic regression models and chi-square for quantitative and qualitative variables (p ≤ 0.05). RESULTS: Responders (37/55) more often had an entrapment or an evident neuroma of the IPBSN (97% vs. 6%). A positive Hoffmann-Tinel sign (p = 0.002) and the absence of knee joint instability (p = 0.029) predicted a positive response of the diagnostic nerve block (90%; 26/29). In the follow-up after therapeutic nerve treatment, all patients with full pain relief showed neuromas or entrapment of the IPBSN. Patients negatively responding to therapeutic nerve treatment more frequently showed an additional knee joint instability (25% vs. 4%). CONCLUSION: Selective denervation for neuropathic knee pain is beneficial in selected patients with significant VAS reduction after diagnostic nerve block. Non-responders following diagnostic nerve block but sonographic evidence of IPBSN pathologies need to be evaluated for other causes such as knee joint instability. KEY POINTS: • Sonographic diagnosis of neuroma or entrapment of the IPBSN is frequently seen in patients with anteromedial knee pain and leads to a good response to diagnostic nerve block following knee surgery. • The vast majority of patients with clinical signs of IPBSN neuropathy and response to a diagnostic nerve block sustained full pain relief following therapeutic nerve treatment. • Patients not responding to therapeutic IPBSN treatment have to be evaluated for other causes of anteromedial knee pain such as knee joint instability.

Correlations of typical pain patterns with SPECT/CT findings in unhappy patients after total knee arthroplasty.

PURPOSE: The diagnostic process in patients after painful total knee arthroplasty (TKA) is challenging. The more clinical and radiological information about a patient with pain after TKA is included in the assessment, the more reliable and sustainable the advice regarding TKA revision can be. The primary aim was to investigate the position of TKA components and evaluate bone tracer uptake (BTU) using pre-revision SPECT/CT and correlate these findings with previously published pain patterns in painful patients after TKA. METHODS: A prospectively collected cohort of 83 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm including 99m-Tc-HDP-SPECT/CT, which led to a diagnosis indicating revision surgery. Pain character, location, dynamics and radiation were systematically assessed as well as TKA component position in 3D-CT. BTU was anatomically localized and quantified using a validated localization scheme. Component positioning and BTU were correlated with pain characteristics using non-parametric Spearman correlations (p < 0.05). RESULTS: Based on Spearman's rho, significant correlations were found between pain and patients characteristics and SPECT/CT findings resulting in nine specific patterns. The most outstanding ones include: Pattern 1: More flexion in the femoral component correlated with tender/splitting pain and patella-related pathologies. Pattern 3: More varus in the femoral component correlated with dull/heavy and tingling/stinging pain during descending stairs, unloading and long sitting in patients with high BMI and unresurfaced patella. Pattern 6: More posterior slope in the tibial component correlated with constant pain. CONCLUSION: The results of this study help to place component positioning in the overall context of the "painful knee arthroplasty" including specific pain patterns. The findings further differentiate the clinical picture of a painful TKA. Knowing these patterns enables a prediction of the cause of the pain to be made as early as possible in the diagnostic process before the state of pain becomes chronic. LEVEL OF EVIDENCE: Level III.

High inter- and intraindividual differences in medial and lateral posterior tibial slope are not reproduced accurately by conventional TKA alignment techniques.

PURPOSE: The purpose of this study was to describe the medial and lateral posterior tibial slope (MPTS and LPTS) on 3D-CT in a Caucasian population without osteoarthritis. It was hypothesised that standard TKA alignment techniques would not reproduce the anatomy in a high percentage of native knees. METHODS: CT scans of 301 knees [male:female = 192:109; mean age 30.1 ([Formula: see text] 6.1)] were analysed retrospectively. Tibial slope was measured medially and laterally in relation to the mechanical axis of the tibia. The proportion of MPTS and LPTS was calculated, corresponding to the "standard PTS" of 3°-7°. The proportion of knees accurately reproduced with the recommended PTS of 0°-3° for PS and 5°-7° for CR TKA were evaluated. RESULTS: Interindividual mean values of MPTS and LPTS did not differ significantly (mean (range); MPTS: 7.2° ( - 1.0°-19.0°) vs. LPTS: 7.2° ( - 2.4°-17.8°), n.s.). The mean absolute intraindividual difference was 2.9° (0.0°-10.8°). In 40.5% the intraindividual difference between MPTS and LPTS was > 3°. When the standard slope of 3°-7° medial and lateral was considered, only 15% of the knees were covered. The tibial cut for a PS TKA or a CR TKA changes the combined PTS (MPTS + LPTS) in 99.3% and 95.3% of cases, respectively. CONCLUSION: A high interindividual range of MPTS and LPTS as well as considerable intraindividual differences were shown. When implementing the recommended slope values for PS and CR prostheses, changes in native slope must be accepted. Further research is needed to evaluate the impact of altering a patient's native slope on the clinical outcome. LEVEL OF EVIDENCE: IV.

Main factors predicting somatic, psychological, and cognitive patient outcomes after significant injury: a pilot study of a simple prognostic tool.

BACKGROUND: There are still insufficient data on the complexity and predictability of patient-related outcomes following trauma. The aim of this study was to assess longer-term outcomes in patients with significant injury and to develop a simple scoring method to identify patients at high risk of subsequent deficits 1-2 years after injury. METHODS: We conducted a prospective cohort study of survivors of significant injury (New Injury Severity Score, NISS greater than or equal to 8), with analysis of patients' 1- to 2-year health-related quality of life (HRQoL) and their functional outcomes based on Short Form-36 (SF-36), Trauma Outcome Profile (TOP), and Quality Of Life after Brain Injury (QOLIBRI). Documented variables suspected or known from the literature to be possible factors associated with outcome were first analysed by univariate analysis, and significant variables were entered into a stepwise logistic regression analysis. Scores predicting longer-term impaired outcome were constructed from risk factors resulting from multivariate analysis. RESULTS: Depending on the patient-reported outcome measure (PROM) used, up to 30 per cent of 1052 study patients (mean NISS 18.6) indicated somatic, 27 per cent psychological, and 54 per cent cognitive deficits. The investigated sociodemographic, injury-related, treatment, and early hospital outcome variables demonstrated only low associations with longer-term outcome in univariate analysis that were highest for preinjury pain or function (R = 0.4) and outcome at hospital discharge (R = 0.3). After logistic regression, the study variables explained a maximum variance of 23 per cent for somatic, 11 per cent for psychological, and 14 per cent for cognitive longer-term outcomes. The resulting Aarau trauma prognostic longer-term outcome scoring (ATPLOS) system, developed by checking eight risk factors, had a specificity of up to 80 per cent, and importantly may facilitate early detection of patients at risk of a poorer longer-term outcome. CONCLUSION: Despite the high rate of deficits recorded for survivors of significant injury, particularly in loss of cognitive function, the multiple variables analysed only led to a limited characterization of patient-related longer-term outcomes. Until more is known about additional individual influencing factors, the proposed scoring system may serve well for clinical evaluation. REGISTRATION NUMBER: NCT02165137 (http://www.clinicaltrials.gov).

Comparative retrieval analysis of antioxidant polyethylene: bonding of vitamin-E does not reduce in-vivo surface damage.

BACKGROUND: With the Persona® knee system a new polyethylene formulation incorporating vitamin-E which aims to reduce oxidation and maintain wear resistance was introduced. Although in-vitro studies have demonstrated positive effects of the vitamin-E antioxidants on UHMWPE, no retrieval study has looked at polyethylene damage of this system yet. It was the aim to investigate the in-vivo performance of this new design, by comparing it with its predecessor in retrieval analysis. METHODS: 15 NexGen® and 8 Persona® fixed-bearing implants from the same manufacturer (Zimmer Biomet) were retrieved from two knee revision centres. For retrieval analysis, a macroscopic analysis of polyethylene using a peer-reviewed damage grading method was used (Hood-score). The roughness of all articulating metal components was measured using a contact profilometer. The reason(s) for TKA revision were recorded. Statistical analyses (t-test) were performed to investigate differences between the two designs. RESULTS: The mean Hood score for Persona® inserts was 109.3 and for NexGen® 115.1 without significant differences between the two designs. Results from the profilometer revealed that Persona® and NexGen® femoral implants showed an identical mean surface roughness of 0.14 µm. The Persona® tibial tray showed a significantly smoother surface (0.06 µm) compared to the NexGen® (0.2 µm; p < 0.001). Both Hood score and surface roughness were influenced by the reasons for revision (p < 0.01). CONCLUSIONS: The bonding of the antioxidant vitamin-E to the PE chain used in the novel Persona® knee system does not reduce in-vivo surface damage compared to highly crosslinked PE without supplemented vitamin-E used in its predecessor knee system NexGen®. However, the Persona® titanium alloy tibial tray showed a significantly smoother surface in comparison to the NexGen® titanium alloy tibial tray. This study provides first retrieval findings of a novel TKA design and may help to understand how the new Persona® anatomic knee system performs in vivo.

Change of tibial tuberosity-trochlear groove (TT-TG) distance during total knee arthroplasty had no influence on clinical outcome and anterior knee pain.

PURPOSE: The main purpose of this study was to determine whether there is a correlation between the change of tibial tuberosity-trochlear groove (TT-TG) distance and clinical outcomes after total knee arthroplasty (TKA). METHODS: A total of 52 knees undergoing TKA due to primary osteoarthritis were included in this retrospective study. All patients had pre- and postoperative CT scans. TT-TG distance was measured by two independent observers and the following alignment parameters were measured: hip-knee ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA), and posterior condylar angle (PCA). Clinical outcome was assessed using Knee Society Score (KSS) pre- and post-operatively and at a minimum of 12-month follow-up. Evidence of AKP was noted from follow-up reports. Pre- and postoperative scores were compared using a paired Student t-test. Pearson correlations were calculated to assess the influence of TT-TG on clinical outcome and of alignment parameters on the change in TT-TG. TT-TG between patients with and without AKP was compared using unpaired Student's t-test (p < 0.05). RESULTS: Neither the absolute postoperative TT-TG nor the amount of change in TT-TG correlated with the post-operative KSS or the change in KSS. Post-operative TT-TG and change in TT-TG did not differ significantly between patients with and patients without AKP. Only the change in FMA showed a correlation with the change in TT-TG (p = 0.01, r = 0.36). CONCLUSION: Despite a missing correlation between outcomes and TT-TG distance in this study, excessive TT-TG distance should be avoided. Furthermore, surgeons need to be aware that changes in femoral joint line orientation might affect TT-TG distance.

Medically graded reduced capacity to work (RCW) following significant injury as explained by patient related outcome measures (PROMs): A prospective trauma center evaluation.

BACKGROUND: Data is limited how well patient-reported longer-term outcome measures (PROMs) explain medically graded reduced capacity for work (RCW). OBJECTIVE: This prospective study investigates the association of RCW with several PROMs in addition to demographic and injury-related variables in significantly injured of working age. METHODS: Patients (New Injury Severity Score, NISS ≥ 8) were recruited consecutively. RCW, as registered by the largest Swiss accident insurer, was tested against demographic, trauma and treatment characteristics, and patients' contemporaneous two year rating of functional outcome and quality of life following trauma with measures such as the Short-Form (SF)-36 or Trauma Outcome Profile (TOP), using uni- and multivariable analysis. RESULTS: 140 patients (mean 42 years, 2-year RCW rate 21%) participated in the longer-term follow-up of self-rated outcome. In multivariable analysis, all investigated baseline factors together accounted for 48% of the variance explaining 2-year postinjury RCW with 31% contributed by demographic, injury or treatment related variables, and 17% by patients' condition at hospital discharge. Patients' self-rated longer-term outcome provided 61% of the information on concurrent RCW, whereby 53% identified worsening of physical function (SF-36) and additional 8% constraints in daily activities (TOP). Four variables (Glasgow Outcome Scale at the time of hospital discharge and SF-36 physical functioning, TOP daily activities, SF-36 role physical at two years) explained 71% of RCW, corresponding to an area under the curve (AUC) of 0.95. CONCLUSIONS: Objectively graded RCW 2 years after injury was found to be well explained by the combined information of patients' subjective longer-term outcome together with basic patient, trauma and treatment characteristics.

AI-based detection and classification of distal radius fractures using low-effort data labeling: evaluation of applicability and effect of training set size.

OBJECTIVES: To evaluate the performance of a deep convolutional neural network (DCNN) in detecting and classifying distal radius fractures, metal, and cast on radiographs using labels based on radiology reports. The secondary aim was to evaluate the effect of the training set size on the algorithm's performance. METHODS: A total of 15,775 frontal and lateral radiographs, corresponding radiology reports, and a ResNet18 DCNN were used. Fracture detection and classification models were developed per view and merged. Incrementally sized subsets served to evaluate effects of the training set size. Two musculoskeletal radiologists set the standard of reference on radiographs (test set A). A subset (B) was rated by three radiology residents. For a per-study-based comparison with the radiology residents, the results of the best models were merged. Statistics used were ROC and AUC, Youden's J statistic (J), and Spearman's correlation coefficient (ρ). RESULTS: The models' AUC/J on (A) for metal and cast were 0.99/0.98 and 1.0/1.0. The models' and residents' AUC/J on (B) were similar on fracture (0.98/0.91; 0.98/0.92) and multiple fragments (0.85/0.58; 0.91/0.70). Training set size and AUC correlated on metal (ρ = 0.740), cast (ρ = 0.722), fracture (frontal ρ = 0.947, lateral ρ = 0.946), multiple fragments (frontal ρ = 0.856), and fragment displacement (frontal ρ = 0.595). CONCLUSIONS: The models trained on a DCNN with report-based labels to detect distal radius fractures on radiographs are suitable to aid as a secondary reading tool; models for fracture classification are not ready for clinical use. Bigger training sets lead to better models in all categories except joint affection. KEY POINTS: • Detection of metal and cast on radiographs is excellent using AI and labels extracted from radiology reports. • Automatic detection of distal radius fractures on radiographs is feasible and the performance approximates radiology residents. • Automatic classification of the type of distal radius fracture varies in accuracy and is inferior for joint involvement and fragment displacement.

Typical Pain Patterns in Unhappy Patients After Total Knee Arthroplasty.

BACKGROUND: The primary aim of this study is to assess characteristics of pain in patients with ongoing pain after total knee arthroplasty (TKA). The secondary aim of this study is to identify specific pain patterns and link these to underlying pathologies. METHODS: A prospectively collected cohort of 97 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm, which led to a diagnosis that set the indication for revision surgery. Character, location, dynamics, and radiation of pain were systematically assessed and correlated with the underlying pathologies. RESULTS: Most frequent pain characters were pricking/lancinating (45.7%), pinching/crushing, and dull/heavy (38.6%); 89.5% of all patients localized their knee pain anteriorly; 48.1% reported pain aggravations by descending stairs. Radiating pain was reported in 14% of the patients. Patella-related problems (56.7%) and instability (52.6%) were the most frequent pathologies. Based on correlations between the characteristics 6 specific pain patterns were identified. The most outstanding ones include the following: pattern 1, instability is associated with jumping/shooting, pricking/lancinating and tugging/wrenching pain, and aggravated by chair raising and starting; pattern 6, pain aggravation by descending stairs is associated with anterior and lateral jumping/shooting, tingling/stinging and sharp/lacerating pain character, and TKA positioning and patella baja. CONCLUSION: The assessment of painful TKA patients involving specific pain patterns help to further differentiate and define the clinical picture and ultimately the cause of a painful TKA. If the causes of the described complaints are known, a decision for a therapy can be made reliably and sustainably at an early stage before the state of pain becomes chronic.

A comparison of femoral component rotation after total knee arthroplasty in Kanekasu radiographs, axial CT slices and 3D reconstructed images.

OBJECTIVE: To compare the posterior condylar angle measured with Kanekasu radiograph and 2D-CT with the gold standard 3D-CT following primary total knee arthroplasty (TKA). METHODS: Eighty-two knees with pain following TKA were included in this retrospective study. Two independent raters measured the anatomical and surgical posterior condylar angles twice on each Kanekasu radiograph and 2D-CT. These measurements were compared against the 3D-CT measurement. The intra- and interrater reliability of the Kanekasu radiograph and 2D-CT and the correlation with 3D-CT were calculated. RESULTS: The intra- and interrater reliability for measurements of the anatomical posterior condyle angle for the Kanekasu radiograph and the 2D-CT were excellent for both raters (0.85-0.92). For the less experienced rater 1, the intrarater reliability was significantly better for 2D-CT than Kanekasu radiograph for measuring both the surgical (p < 0.01) and anatomical posterior condyle angles (p < 0.05). For the experienced rater 2, the intrarater reliability was significantly better for Kanekasu radiograph than 2D-CT for measurement of the surgical posterior condyle angle (p < 0.05). The correlation with 3D-CT is higher in 2D-CT than in Kanekasu radiograph (p < 0.01). While the Kanekasu radiograph predicts the 3D-CT angle with 65.9%, 2D-CT can measure the true angle with 82.9% certainty. CONCLUSION: Measurements using the anatomical transepicondylar axis are easier to replicate compared to the surgical transepicondylar axis. In comparison with the gold standard 3D-CT, 2D-CT showed a significantly higher correlation with 3D-CT than the Kanekasu measurements. If 3D-CT is available, it should be preferred over 2D-CT and Kanekasu view radiograph for femoral component rotation measurements.