Greater hip internal rotation range of motion is associated with increased dynamic knee valgus during jump landing, both before and after fatigue.

PURPOSE: The aim of this study was to analyse sex-specific differences contributing to dynamic valgus in competitive soccer players before and after a standardised fatiguing protocol. METHODS: Thirty-nine healthy female and male competitive soccer players (19 females and 20 males) were recruited for the purpose of this study. Bilateral medial knee displacement (MKD) was assessed during drop jump landings using a three-dimensional motion capture system before and after a standardised fatiguing protocol. In addition, all soccer players underwent clinical examinations, including rotational hip range of motion (ROM), isokinetic strength testing and magnetic resonance imaging (MRI) of the hip and knee. Sex-specific and fatigue-dependent differences were reported, and the influence of demographic, clinical and radiographic factors on MKD was analysed via multiple linear regression models. RESULTS: Compared with male soccer players, female soccer players demonstrated a tendency towards increased MKD during drop jump landings before (p = 0.09) and after the fatiguing protocol (p = 0.04). Sex-specific differences included increased hip internal rotation (IR) ROM, decreased hip external rotation (ER) strength and increased femoral torsion in females (all p < 0.002). According to the multiple linear regression models (stepwise method), increased hip IR ROM (90° of flexion) and the non-dominant leg remained the sole independent predictors of increased MKD during drop jump landings before (p < 0.01 and p = 0.02, respectively) and after fatigue (p < 0.01 and p < 0.01, respectively). An increase in hip IR ROM in females was linearly related to MKD after fatigue (R2 = 0.25; p < 0.01). CONCLUSION: Female soccer players exhibited increased dynamic valgus before and after fatigue, which is likely attributed to joint mobility, as well as muscular and anatomical differences, such as increased hip IR ROM, reduced hip ER strength and increased femoral torsion. In particular, females with increased hip IR ROM were more susceptible to effects of fatigue on MKD, which may increase their risk for anterior cruciate ligament injury. LEVEL OF EVIDENCE: Level III.

The influence of the weight-bearing state on three-dimensional (3D) planning in lower extremity realignment - analysis of novel vs. state-of-the-art planning approaches.

BACKGROUND: The use of 3D planning to guide corrective osteotomies of the lower extremity is increasing in clinical practice. The use of computer-tomography (CT) data acquired in supine position neglects the weight-bearing (WB) state and the gold standard in 3D planning involves the manual adaption of the surgical plan after considering the WB state in long-leg radiographs (LLR). However, this process is subjective and dependent on the surgeons experience. A more standardized and automated method could reduce variability and decrease costs. PURPOSE: The aim of the study was (1) to compare three different three-dimensional (3D) planning modalities for medial open-wedge high tibial osteotomy (MOWHTO) and (2) to describe the current practice of adapting NWB CT data after considering the WB state in LLR. The purpose of this study is to validate a new, standardized approach to include the WB state into the 3D planning and to compare this method against the current gold standard of 3D planning. Our hypothesis is that the correction is comparable to the gold standard, but shows less variability due compared to the more subjective hybrid approach. METHODS: Three surgical planning modalities were retrospectively analyzed in 43 legs scheduled for MOWHTO between 2015 and 2019. The planning modalities included: (1) 3D hybrid (3D non-weight-bearing (NWB) CT models after manual adaption of the opening angle considering the WB state in LLR, (2) 3D NWB (3D NWB CT models) and (3) 3D WB (2D/3D registration of 3D NWB CT models onto LLR to simulate the WB state). The pre- and postoperative hip-knee-ankle angle (HKA) and the planned opening angle (°) were assessed and differences among modalities reported. The relationship between the reported differences and BMI, preoperative HKA (LLR), medial meniscus extrusion, Outerbridge osteoarthritis grade and joint line convergence angle (JLCA) was analyzed. RESULTS: The mean (std) planned opening angle of 3D hybrid did not differ between 3D hybrid and 3D WB (0.4 ± 2.1°) (n.s.) but was higher in 3D hybrid compared to 3D NWB (1.1° ± 1.1°) (p = 0.039). 3D WB demonstrated increased preoperative varus deformity compared to 3D NWB: 6.7 ± 3.8° vs. 5.6 ± 2.7° (p = 0.029). Patients with an increased varus deformity in 3D WB compared to 3D NWB (> 2 °) demonstrated more extensive varus alignment in LLR (p = 0.009) and a higher JLCA (p = 0.013). CONCLUSION: Small intermodal differences between the current practice of the reported 3D hybrid planning modality and a 3D WB approach using a 2D/3D registration algorithm were reported. In contrast, neglecting the WB state underestimates preoperative varus deformity and results in a smaller planned opening angle. This leads to potential under correction in MOWHTO, especially in patients with extensive varus deformities or JLCA. CLINICAL RELEVANCE: Incorporating the WB state in 3D planning modalities has the potential to increase accuracy and lead to a more consistent and reliable planning in MOWHTO. The inclusion of the WB state in automatized surgical planning algorithms has the potential to reduce costs and time in the future.

Operative vs. conservative treatment of AC-Joint Dislocations Rockwood grade ≥ III -An economical and clinical evaluation.

INTRODUCTION: Acromioclavicular joint dislocations (ACD) are one of the most common shoulder injuries. There is no consensus in how to treat higher graded ACD ≥ Rockwood grade III. This study compares operative versus conservative treatment regarding costs and clinical outcome parameters. MATERIALS AND METHODS: This retrospective, consecutive case-control-study includes 14 patients. Seven operatively treated patients were matched, by Rockwood grade, with seven conservatively treated patients. The cost was extracted out of the clinical- and insurance-based cost sheets and furthermore these include the loss of earnings. Clinical examination, demographic data as well as different outcome-questionnaires were recorded. RESULTS: There were no significant differences between operative and conservative treated patients for outcome Questionnaires. Of note, there was a significantly higher incidence of tenderness over the AC-joint (p = 0.0038) postoperatively. As expected, economical evaluation showed various findings in favor of the conservative treatment. The costs for medical services (11012.39vs.1163.81USD; p = 0.0061), days of hospitalization (3.3vs.0days; p < 0.0001); total cost for medical treatment (30262.17 vs. 7833.82 USD; p = 0.0358) were significantly higher in the operative group. CONCLUSION: Even with a limited case number and a retrospective study design almost all clinical results were equal in both groups. Operative therapy of higher graded ACDs (Rockwood > III) compared to conservative is economically inefficient. Under consideration of clinical comparable results, indications for operative treatment should be set very carefully.

Factors affecting augmented reality head-mounted device performance in real OR.

PURPOSE: Over the last years, interest and efforts to implement augmented reality (AR) in orthopedic surgery through head-mounted devices (HMD) have increased. However, the majority of experiments were preclinical and within a controlled laboratory environment. The operating room (OR) is a more challenging environment with various confounding factors potentially affecting the performance of an AR-HMD. The aim of this study was to assess the performance of an AR-HMD in a real-life OR setting. METHODS: An established AR application using the HoloLens 2 HMD was tested in an OR and in a laboratory by two users. The accuracy of the hologram overlay, the time to complete the trial, the number of rejected registration attempts, the delay in live overlay of the hologram, and the number of completely failed runs were recorded. Further, different OR setting parameters (light condition, setting up partitions, movement of personnel, and anchor placement) were modified and compared. RESULTS: Time for full registration was higher with 48 s (IQR 24 s) in the OR versus 33 s (IQR 10 s) in the laboratory setting (p < 0.001). The other investigated parameters didn't differ significantly if an optimal OR setting was used. Within the OR, the strongest influence on performance of the AR-HMD was different light conditions with direct light illumination on the situs being the least favorable. CONCLUSION: AR-HMDs are affected by different OR setups. Standardization measures for better AR-HMD performance include avoiding direct light illumination on the situs, setting up partitions, and minimizing the movement of personnel.

Influence of medial open wedge high tibial osteotomy on tibial tuberosity-trochlear groove distance.

PURPOSE: Medial open wedge high tibial osteotomy (MOWHTO) is an effective treatment option for realignment of a varus knee. However, a simple supra-tuberositary osteotomy can lead to patella baja and potentially increases the tibial tuberosity-trochlear groove distance (TTTG). The purpose of this study was to quantify the influence of MOWHTO on TTTG. METHODS: Three-dimensional (3D) surface models of five lower extremities with a varus hip-knee-ankle angle (HKA) and a borderline TTTG (≥ 15 mm), five lower extremities with a varus HKA and a normal TTTG (< 15 mm) and a 3D statistical shape model (SSM) of a neutrally aligned healthy knee were analysed by simulating MOWHTO with a stepwise increment of one degree of valgisation from the preoperative coronal deformity (0°-15°) for each patient, resulting in a total of 165 simulations. Postoperative 3D TTTG and tibial torsion (TT) were measured for each simulation. A mathematical formula was developed to calculate the increase of TTTG after MOWHTO. Mean differences between simulated and calculated TTTG were analysed. RESULTS: Mean preoperative HKA was 6.5 ± 3.0° varus (range 0.8°-11.5°). Mean TTTG increased from 14.2 ± 3.2 mm (range 9.6-19.1) preoperatively to 18.8 ± 3.8 mm (range 14.5-25.0) postoperatively (p = 0.001). TTTG increased approximately linear by + 0.5 ± 0.2° (range 0.3-0.8) per 1° of valgisation with a high positive correlation (0.99, p = 0.001) from 0° to 15°. Mean difference between simulated and calculated TTTG was 0.03 ± 0.02 mm (range 0.01-0.07) per 1° of valgisation (p < 0.001). CONCLUSION: MOWHTO results in an approximately linear increase in TTTG of + 0.5 mm per 1° of valgisation in the range from 0° to 15° and the lateralisation of the tibial tuberosity can be calculated reliably using the described formula. Preoperative analysis of TTTG in patients undergoing MOWHTO may prevent unintentional patellofemoral malalignment. LEVEL OF EVIDENCE: III.

Increased femoral curvature and trochlea flexion in high-grade patellofemoral dysplastic knees.

PURPOSE: High-grade patellofemoral dysplasia is often associated with concomitant axial and frontal leg malalignment. However, curvature of the femur and sagittal flexion of the trochlea has not yet been studied in patellofemoral dysplastic knees. The aim of the study was to quantify the femoral curvature and sagittal flexion of the trochlea in both high-grade patellofemoral dysplastic and healthy knees. METHODS: A retrospective case-control study matched 19 high-grade patellofemoral dysplastic knees (Dejour types C and D) with 19 healthy knees according to sex and body mass index. Three-dimensional (3D) femoral curvature and sagittal trochlea flexion were analysed. To analyse femoral curvature, the specific 3D radius of curvature (ROC) was calculated. Trochlear flexion was quantified through the development of the trochlea flexion angle (TFA), which is a novel 3D measurement in relation to the anatomical and mechanical femur axis and is referred to as 3D TFAanatomic and 3D TFAmech. The influence of age, gender, height, weight and frontal and axial alignment on ROC and TFA was analysed in a multiple regression model. RESULTS: Overall ROC was significantly smaller in dysplastic knees, compared with the control group [898.4 ± 210.8 mm (range 452.9-1275.1 mm) vs 1308.4 ± 380.5 mm (range 878.3-2315.8 mm), p < 0.001]. TFA was significantly higher in dysplastic knees, compared with the control group, for 3D TFAmech [13.8 ± 7.2° (range 4.4-33.4°) vs 6.5 ± 2.3° (range 0.8-10.2°), p < 0.001] and 3D TFAanatomic [12.5 ± 7.2° (range 3.1-32.2°) vs 6.4 ± 1.9° (range 2.1-9.1°), p = 0.001]. A smaller ROC was associated with smaller height, female gender and higher femoral ante torsion. An increased TFA was associated with valgus malalignment. CONCLUSION: High-grade patellofemoral dysplastic knees demonstrated increased femoral curvature and sagittal flexion of the trochlea, compared with healthy knees. The ROC and newly described TFA allowed the quantification of the sagittal femoral deformity. TFA and ROC should be incorporated in future deformity analysis to investigate their potential as a target for surgical correction. LEVEL OF EVIDENCE: Level III.

No relevant mechanical leg axis deviation in the frontal and sagittal planes is to be expected after subtrochanteric or supracondylar femoral rotational or derotational osteotomy.

PURPOSE: The purpose of this study was to investigate if one level of corrective femoral osteotomy (subtrochanteric or supracondylar) bears an increased risk of unintentional implications on frontal and sagittal plane alignment in a simulated clinical setting. METHODS: Out of 100 cadaveric femora, 23 three-dimensional (3-D) surface models with femoral antetorsion (femAT) deformities (> 22° or < 2°) were investigated, and femAT normalized to 12° with single plane rotational osteotomies, perpendicular to the mechanical axis of the femur. Change of the frontal and sagittal plane alignment was expressed by the mechanical lateral distal femoral angle (mLDFA) and the posterior distal femoral angle (PDFA), respectively. The influence of morphologic factors of the femur [centrum-collum-diaphyseal (CCD) angle and antecurvatum radius (ACR)] were assessed. Furthermore, position changes of the lesser (LT) and greater trochanters (GT) in the frontal and sagittal plane compared to the hip centre were investigated. RESULTS: Mean femoral derotation of the high-antetorsion group (n = 6) was 12.3° (range 10-17°). In the frontal plane, mLDFA changed a mean of 0.1° (- 0.06 to 0.3°) (n.s.) and - 0.3° (- 0.5 to - 0.1) (p = 0.03) after subtrochanteric and supracondylar osteotomy, respectively. In the sagittal plane, PDFA changed a mean of 1° (0.7 to 1.1) (p = 0.03) and 0.3° (0.1 to 0.7) (p = 0.03), respectively. The low-antetorsion group (n = 17) was rotated by a mean of 13.8° (10°-23°). mLDFA changed a mean of - 0.2° (- 0.5° to 0.2°) (p < 0.006) and 0.2° (0-0.5°) (p < 0.001) after subtrochanteric and supracondylar osteotomy, respectively. PDFA changed a mean of 1° (- 2.3 to 1.3) (p < 0.01) and 0.5° (- 1.9 to 0.3) (p < 0.01), respectively. The amount of femAT correction was associated with increased postoperative deviation of the mechanical leg axis (p < 0.01). Using multiple regression analysis, no other morphological factors were found to influence mLDFA or PDFA. Internal rotational osteotomies decreased the ischial-lesser trochanteric space by < 5 mm in both the frontal and sagittal plane (p < 0.001). CONCLUSIONS: In case of femAT correction of ≤ 20°, neither subtrochanteric nor supracondylar femoral derotational or rotational osteotomies have a clinically relevant impact on frontal or sagittal leg alignment. A relevant deviation in the sagittal (but not frontal plane) might occur in case of a > 25° subtrochanteric femAT correction. LEVEL OF EVIDENCE: IV.

Extent of posterolateral tibial plateau impaction fracture correlates with anterolateral complex injury and has an impact on functional outcome after ACL reconstruction.

PURPOSE: The impact of posterolateral tibial plateau impaction fractures (TPIF) on posttraumatic knee stability in the setting of primary anterior cruciate ligament (ACL) tear is unknown. The main objective was to determine whether increased bone loss of the posterolateral tibial plateau is associated with residual rotational instability and impaired functional outcome after ACL reconstruction. METHODS: A cohort was identified in a prospective enrolled study of patients suffering acute ACL injury who underwent preoperative standard radiographic diagnostics and clinical evaluation. Patients were included when scheduled for isolated single-bundle hamstring autograft ACL reconstruction. Exclusion criteria were concurrent anterolateral complex (ALC) reconstruction (anterolateral tenodesis), previous surgery or symptoms in the affected knee, partial ACL tear, multi-ligament injury with an indication for additional surgical intervention, and extensive cartilage wear. On MRI, bony (TPIF, tibial plateau, and femoral condyle morphology) and ligament status (ALC, concomitant collateral ligament, and meniscus injuries) were assessed by a musculoskeletal radiologist. Clinical evaluation consisted of KT-1000, pivot-shift, and Lachman testing, as well as Tegner activity and IKDC scores. RESULTS: Fifty-eight patients were included with a minimum follow-up of 12 months. TPIF was identified in 85% of ACL injuries (n = 49). The ALC was found to be injured in 31 of 58 (53.4%) cases. Pearson analysis showed a positive correlation between TPIF and the degree of concomitant ALC injury (p < 0.001). Multiple regression analysis revealed an increased association of high-grade TPIF with increased lateral tibial convexity (p = 0.010). The high-grade TPIF group showed worse postoperative Tegner scores 12 months postoperatively (p = 0.035). CONCLUSION: Higher degrees of TPIFs are suggestive of a combined ACL/ALC injury. Moreover, patients with increased posterolateral tibial plateau bone loss showed lower Tegner activity scores 12 months after ACL reconstruction. LEVEL OF EVIDENCE: III.

Excessive femoral torsion is not associated with patellofemoral pain or instability if TKA is functionally aligned and the patella denervated.

PURPOSE: Recent data suggest that individual morphologic factors should be respected to restore preoperative patellofemoral alignment and thus reduce the likelihood of anterior knee pain. The goal of this study was to investigate the effect of excessive femoral torsion (FT) on clinical outcome of TKA. METHODS: Patients who underwent TKA and complete preoperative radiographic evaluation including a long-leg radiograph and CT scan were included. 51 patients showed increased FT of > 20° and were matched for age/sex to 51 controls (FT < 20°). Thirteen patients were lost to follow-up. Thirty-eight matched pairs were compared after a 2 year follow-up clinically (Kujala and patellofemoral score for TKA) and radiographically (FT, frontal leg axis, TT-TG, patellar thickness, patellar tilt, and lateral displacement of patella). Functional alignment of TKA was performed (hybrid-technique). All patellae were denervated but no patella was resurfaced. RESULTS: There was no significant difference between clinical scores two years after surgery between patients with normal and excessive FT (n.s.). Kujala score was 64.3 ± 16.7 versus 64.8 ± 14.4 (n.s.), and patellofemoral score for TKA was 74.3 ± 21 versus 78.5 ± 20.7 (n.s.) for increased FT group and control group, respectively. There was no correlation between preoperative FT and clinical scores. Other radiographic parameters were similar between both groups. No correlations between clinical outcomes and preoperative/postoperative frontal leg axis or total leg axis correction were found (n.s.). CONCLUSION: If the leg axis deformity is corrected to a roughly neutral alignment during cemented TKA, including patellar denervation, then excessive FT was not associated with patellofemoral pain or instability. LEVEL OF EVIDENCE: Prospective comparative study, level II.

The relationship between pelvic tilt, frontal, and axial leg alignment in healthy subjects.

INTRODUCTION: The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal, and axial leg alignment remains unclear. The aim of the study was to analyze the relationship between pelvic tilt and frontal and axial leg alignment in healthy subjects. MATERIAL AND METHODS: Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), hip-knee-ankle angle (HKA), femoral antetorsion and tibial torsion were measured using SterEOS (EOS Imaging) software. EOS was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of HKA, femoral antetorsion, tibial torsion and gender on pelvic tilt was analyzed in a univariate correlation and multiple regression model. RESULTS: Sixteen female subjects and 14 male subjects with a mean age of 27.1 years ± 10 (range 20-67) were included. HKA, femoral antetorsion, and tibial torsion correlated with anterior pelvic tilt in univariate analysis (all p < 0.05). Anterior pelvic tilt increased 1.1° (95% CI: 0.7 to 1.5) per 1° of knee valgus (p < 0.001) and 0.5° (95% CI: 0.3 to 0.7) per 1° of external tibial torsion (p < 0.001). Overall, linear regression model fit explained 39% of variance in pelvic tilt by the HKA, femoral antetorsion and tibial torsion (R2 = 0.385; p < 0.001). CONCLUSION: Valgus alignment and increasing tibial torsion demonstrated a weak correlation with an increase in anterior pelvic tilt in healthy subjects when placing their feet anteriorly. The relationship between frontal, axial leg alignment and pelvic tilt needs to be considered in patients with multiple joint disorders at the hip, knee and spine. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the pelvic tilt when the FPA is kept constant.

3D planning and patient specific instrumentation for intraarticular corrective osteotomy of trapeziometacarpal-, metacarpal and finger joints.

BACKGROUND: Intra-articular malunions of the finger can lead to deformity and loss of function and can be treated with intra-articular corrective osteotomies. The aim of this study was to evaluate radiographic joint congruency, feasibility and functional outcome of three-dimensional (3D) printed patient-specific instrumentation (PSI) for corrective osteotomies at the trapeziometacarpal and finger joints. METHODS: Computer-tomography (CT) scans were acquired preoperatively for standard 3D planning, which was followed by calculation of cutting planes and the design of individualized bone surface contact drilling, sawing and reposition guides. Follow-up CT scans and clinical examinations (range of motion, grip strength) were performed. Postoperative complications were documented and patient-reported outcome measurements were assessed (Single Assessment Numeric Evaluation (SANE) score, brief Michigan Hand Questionnaire (MHQ)). RESULTS: Ten patients (mean age 28.4 ± 12.8,range 13.8-51.3) years) were included with a mean follow-up of 21 ± 18 (3-59) months including seven osteotomies at the trapeziometacarpal or metacarpophalangeal joints and three at the proximal interphalangeal joint (PIP). All radiographic follow-up examinations showed the planned correction with good joint congruency and regular osseous consolidation. At the latest follow-up, the range of motion (ROM) increased and the average grip strength recovered to the level of the contralateral side. No postoperative complication was detected. The mean SANE score improved from 44 ± 23 (0-70) to 82 ± 12 (60-90) after a mean of 72 ± 20 (44-114) months. The mean postoperative brief MHQ was 92 ± 8 (71-98). CONCLUSION: The use of 3D PSI in treating intra-articular malunions at the trapeziometacarpal and finger joints restored articular congruency accurately. ROM and grip strength improved postoperatively comparable to the healthy contralateral side and patient-reported outcome measures improved after medium-term follow-up.

Introducing a brain-computer interface to facilitate intraoperative medical imaging control - a feasibility study.

BACKGROUND: Safe and accurate execution of surgeries to date mainly rely on preoperative plans generated based on preoperative imaging. Frequent intraoperative interaction with such patient images during the intervention is needed, which is currently a cumbersome process given that such images are generally displayed on peripheral two-dimensional (2D) monitors and controlled through interface devices that are outside the sterile filed. This study proposes a new medical image control concept based on a Brain Computer Interface (BCI) that allows for hands-free and direct image manipulation without relying on gesture recognition methods or voice commands. METHOD: A software environment was designed for displaying three-dimensional (3D) patient images onto external monitors, with the functionality of hands-free image manipulation based on the user's brain signals detected by the BCI device (i.e., visually evoked signals). In a user study, ten orthopedic surgeons completed a series of standardized image manipulation tasks to navigate and locate predefined 3D points in a Computer Tomography (CT) image using the developed interface. Accuracy was assessed as the mean error between the predefined locations (ground truth) and the navigated locations by the surgeons. All surgeons rated the performance and potential intraoperative usability in a standardized survey using a five-point Likert scale (1 = strongly disagree to 5 = strongly agree). RESULTS: When using the developed interface, the mean image control error was 15.51 mm (SD: 9.57). The user's acceptance was rated with a Likert score of 4.07 (SD: 0.96) while the overall impressions of the interface was rated as 3.77 (SD: 1.02) by the users. We observed a significant correlation between the users' overall impression and the calibration score they achieved. CONCLUSIONS: The use of the developed BCI, that allowed for a purely brain-guided medical image control, yielded promising results, and showed its potential for future intraoperative applications. The major limitation to overcome was noted as the interaction delay.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length.

BACKGROUND: Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries. METHODS: The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed. RESULTS: ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient. Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0-2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54-0.85) (p = 0.03) and an accuracy of 79%. CONCLUSION: ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears. STUDY DESIGN: Cohort study; Level of evidence, 3.

The winking sign is an indicator for increased femorotibial rotation in patients with recurrent patellar instability.

PURPOSE: Rotation of the tibia relative to the femur was recently identified as a contributing risk factor for patellar instability, and correlated with its severity. The hypothesis was that in patellofemoral dysplastic knees, an increase in femorotibial rotation can be reliably detected on anteroposterior (AP) radiographs by an overlap of the lateral femoral condyle over the lateral tibial eminence. METHODS: Sixty patients (77 knees) received low-dose computed tomography (CT) of the lower extremity for assessment of torsional malalignment due to recurrent patellofemoral instability. Three-dimensional (3D) surface models were created to assess femorotibial rotation and its relationship to other morphologic risk factors of patellofemoral instability. On weight-bearing AP knee radiographs, a femoral condyle/lateral tibial eminence superimposition was defined as a positive winking sign. Using digitally reconstructed radiographs of the 3D models, susceptibility of the winking sign to vertical/horizontal AP knee radiograph malrotation was investigated. RESULTS: A positive winking sign was present in 30/77 knees (39.0%) and indicated a 6.3 ± 1.4° increase in femorotibial rotation (p < 0.001). Femoral condyle/tibial eminence superimposition of 1.9 mm detected an increased femorotibial rotation (> 15°) with 43% sensitivity and 90% specificity (AUC = 0.72; p = 0.002). A positive winking sign (with 2 mm overlap) disappeared in case of a 10° horizontally or 15° vertically malrotated radiograph, whereas a 4 mm overlap did not disappear at all, regardless of the quality of the radiograph. In absence of a winking sign, on the other hand, no superimposition resulted within 20° of vertical/horizontal image malrotation. Femorotibial rotation was positively correlated to TT-TG (R2 = 0.40, p = 0.001) and patellar tilt (R2 = 0.30, p = 0.001). CONCLUSIONS: The winking sign reliably indicates an increased femorotibial rotation on a weight-bearing AP knee radiograph and could prove useful for day-by-day clinical work. Future research needs to investigate whether femorotibial rotation is not only a prognostic factor but a potential surgical target in patients with patellofemoral disorders. LEVEL OF EVIDENCE: III.

Incidence, radiographic predictors, and clinical outcome of acromial stress reaction and acromial fractures in reverse total shoulder arthroplasty.

BACKGROUND: Acromial and scapular spine fractures (ASFs) are known complications following implantation of reverse total shoulder arthroplasty (RTSA). The entity of acromial stress reaction (ASR) without fracture has recently been described. The purpose of this study was to analyze the incidence, radiographic predictors, treatment options, healing rates, and clinical outcomes of ASF and ASR compared with a control group. METHODS: A total of 854 primary RTSAs were implanted between 2005 and 2018 in a single shoulder unit of a tertiary referral hospital and retrospectively reviewed for the incidence of ASF and ASR. ASR was defined as pain at the acromion or scapular spine after fracture exclusion on computed tomography scans. The ASF group was matched to a control group. Preoperative and postoperative radiographs were analyzed for radiographic predictors of ASF or ASR. The impact of ASF and ASR, operative vs. nonoperative treatment, and fracture union on clinical outcomes (Constant-Murley score [CS], Subjective Shoulder Value [SSV], and range of motion) with a minimum follow-up period of 2 years was analyzed. RESULTS: A total of 46 ASFs (5.4%) in 44 patients and 44 ASRs (5.2%) in 43 patients were detected at a mean of 16 ± 24 months and 20 ± 23 months postoperatively, respectively. Predictive radiographic factors were an increased critical shoulder angle and lateralization shoulder angle. The overall union rate was 55% (22 of 40) but was significantly higher following operative treatment (9 of 11, 82%) compared with nonoperative treatment (13 of 29, 45%). Patients with ASF or ASR demonstrated inferior clinical outcomes (CS, 44 ± 21 and 48 ± 18; SSV, 52% ± 25% and 57% ± 27%) compared with the control group (CS, 66 ± 14; SSV, 82% ± 22%) independent of bony union or treatment at a mean of 59 ± 33 months (ASF) and 61 ± 38 months (ASR). CONCLUSION: ASF and ASR are frequent complications following RTSA implantation with similar poor clinical outcome measures. The healing rate was shown to be much higher with a surgical approach. Nevertheless, fracture consolidation does not result in better clinical outcomes compared with nonunion.

Plantar Plating in the Modified Lapidus Procedure: Evaluation of Function and Impairment of the Tibialis Anterior Tendon.

The modified "Lapidus" procedure (MLP) describes the arthrodesis of the first tarsometatarsal joint. We investigate if there are detectable changes of the tendon or the function of the muscle and clinical outcome after MLP. We reviewed 22 feet. All patients underwent magnetic resonance imaging (MRI) at an average of 27 (range, 12-49) months. Clinical outcome was evaluated using the European Foot and Ankle Society score. Strength was measured and complications were assessed. MRI revealed signs of tendinopathy of the tibialis anterior tendon in 13 feet (59%). The mean total European Foot and Ankle Society score at final follow-up was 17 (range, 6-24) points. The mean postoperative Visual Analog Scale score was 1.4 (range, 0-5). Range of motion and force data were not significantly different to the contralateral side. In conclusion, MRI showed signs of tendinopathy in 59%, which does not seem to affect clinical outcome, but has to be considered when choosing the desired implant and placement. MLP leads to high patient satisfaction rates and significant improvement at midterm follow up.

The Metatarsal Cortical Index as an Indicator of Insufficiency Fracture of the Foot.

The diagnosis of metatarsal stress fractures is challenging. Standard imaging often shows false-negative results. The aim of this study was to create reliable radiologic outcome parameters to predict insufficiency fractures of the metatarsals. We performed an age- and sex-matched case-control study of patients with (n = 18) and without insufficiency fracture (n = 18) of the foot. The metatarsal cortical index (MCI) for each metatarsal was developed to predict an insufficiency fracture. The MCI of each metatarsal was significantly decreased in the insufficiency fracture group compared with the control group (p < .01). The MCI of the fourth ray yielded the highest area under the curve among the analyzed MCI values (area under the curve, 0.79; 95% confidence interval, 0.61-0.90). A cut-off value of 1.62 for the MCI of the fourth ray yielded a sensitivity of 78% and a specificity of 78% to predict insufficiency fracture of the foot (odds ratio, 12.25; 95% confidence interval, 2.54-58.97), and enabled accurate allocation to the insufficiency fracture group versus the control group in 74% of cases. In conclusion, a decreased MCI is associated with metatarsal insufficiency fractures and enables an accurate diagnosis in 3 out of 4 cases. The MCI might aid clinicians in identifying insufficiency fracture, and raise the suspicion of the diagnosis without additional imaging studies.

Minimally invasive arthrodesis of the first metatarsophalangeal joint: A systematic literature review.

AIM: Currently, cohort studies reported the use of minimally invasive arthrodesis of the first metatarsophalangeal joint (MTP I). The aim of this systematic literature review was to analyse clinical, radiological outcome and complications with this technique. METHODS: A systemic literature search of the databases Google Scholar, PubMed, Scopus, EMBASE and Cochrane to identify studies reporting on clinical, radiological outcome or complications of minimally invasive MTP I arthrodesis was conducted. RESULTS: A total of 6 studies (1 Level V, 5 Level IV) reporting on 109 minimally invasive MTP arthrodesis in 105 patients were included. Validated scores were reported in 103 cases. Clinical outcome improved in 57 cases from a mean of 36.9 to 82.6 points American Orthopedic Foot and Ankle Score (AOFAS) and in 46 cases from 38.7 to 18.4 points Manchester Oxford Foot Questionnaire (MOXFQ). Radiological fusion rate was 87% (n = 94 out of 109) achieved after 6-12 weeks. Overall complication rate was 11.9% (13 cases) leading to revision surgeries in 5.5% (6 cases). Most common complications Most common complications were symptomatic non-union (n = 6, 5.5%), asymptomatic non-union (n = 2, 1.8%) and subsequent interphalangeal joint arthritis (n = 2, 1.8%). CONCLUSION: Minimally invasive MTP I arthrodesis is a promising technique with comparable clinical, radiological outcome and complication rates to open surgery in hallux rigidus and rigido-valgus. Future studies are needed providing higher level of evidence to prove the potential benefit of minimally invasive compared to open MTP I arthrodesis.

Carbon fibre/polyether ether ketone (CF/PEEK) implants in orthopaedic oncology.

BACKGROUND: Radiation therapy is an important therapeutic element in musculoskeletal tumours, especially when encountering multiple or painful lesions. In osteolytic lesions, a surgical stabilization with implants is often required. However, metallic implants not only complicate the CT-based planning of a subsequent radiation therapy, but also have an uncontrollable dose-modulating effect in adjuvant radiotherapy. In addition, follow-up imaging and the diagnosis of local recurrences are often obscured by metallic artefacts. Radiolucent implants consisting of carbon/polyether ether ketone (CF/PEEK) therefore facilitate adjuvant radiation therapy and follow-up imaging of bone lesions. We hereby present clinical cases with application of CF/PEEK implants in orthopaedic tumour surgery. METHODS: We report a single-centre experience of three selected patients with surgical stabilization of osteolytic bone lesions using CF/PEEK implants. Detailed information about the clinical presentation, preoperative considerations, surgical procedures and postoperative results is provided for each case. RESULTS: One spinal lesion (T12 vertebral body), one lesion of the upper extremity (humerus) and one of the lower extremities (tibia) were surgically stabilized with use of CF/PEEK implants. With a mean follow-up of 12 months (range 6-25 months), no adverse events were observed. Two patients received adjuvant radiotherapy. Follow-up imaging was obtained in all patients. CONCLUSION: The applicability of CF/PEEK implants in orthopaedic tumour surgery is good with respect to postoperative follow-up imaging, application of adjuvant radiotherapy and intraoperative handling. As a result of the unique material properties, oncological patients might particularly benefit from CF/PEEK implants.