Modeling of the native knee with kinematic data derived from experiments using the VIVO™ joint simulator: a feasibility study.

BACKGROUND: Despite advances in total knee arthroplasty, many patients are still unsatisfied with the functional outcome. Multibody simulations enable a more efficient exploration of independent variables compared to experimental studies. However, to what extent numerical models can fully reproduce knee joint kinematics is still unclear. Hence, models must be validated with different test scenarios before being applied to biomechanical questions. METHODS: In our feasibility study, we analyzed a human knee specimen on a six degree of freedom joint simulator, applying a passive flexion and different laxity tests with sequential states of ligament resection while recording the joint kinematics. Simultaneously, we generated a subject-specific multibody model of the native tibiofemoral joint considering ligaments and contact between articulating cartilage surfaces. RESULTS: Our experimental data on the sequential states of ligament resection aligned well with the literature. The model-based knee joint kinematics during passive flexion showed good agreement with the experiment, with root-mean-square errors of less than 1.61 mm for translations and 2.1° for knee joint rotations. During laxity tests, the experiment measured up to 8 mm of anteroposterior laxity, while the numerical model allowed less than 3 mm. CONCLUSION: Although the multibody model showed good agreement to the experimental kinematics during passive flexion, the validation showed that ligament parameters used in this feasibility study are too stiff to replicate experimental laxity tests correctly. Hence, more precise subject-specific ligament parameters have to be identified in the future through model optimization.

An anteromedial stabilization procedure has the most protective effect on the anterior cruciate ligament in tibial external rotation. A human knee model study.

INTRODUCTION: Anterior cruciate ligament (ACL) reconstruction remains associated with the risk of re-rupture and persisting rotational instability. Additional extraarticular anterolateral stabilization procedures stabilize the tibial internal rotation and lead to lower ACL failure rate and improved knee stability. However, data for additional stabilization of tibial external rotation is lacking and the importance of an anteromedial stabilization procedure is less well evaluated. Aim of this study is to investigate the influence of an extraarticular anteromedial stabilization procedure for the stabilization of the tibial external rotation and protection of the ACL from these rotational forces. METHODS: Internal and external rotations of the tibia were applied to a finite element (FE) model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Five additional anatomic structures (Anteromedial stabilization/anteromedial ligament, AML, augmented superficial medial collateral ligament, sMCL, posterior oblique ligament, POL, anterolateral ligament, ALL, and popliteal tendon, PLT) were added to the FE model separately and then combined. The force histories within all structures were measured and determined for each case. RESULTS: The anteromedial stabilization or imaginary AML was the main secondary stabilizer of tibial external rotation (90% of overall ACL force reduction). The AML reduced the load on the ACL by 9% in tibial external rotation which could not be achieved by an augmented sMCL (-1%). The AML had no influence in tibial internal rotation (-1%). In the combined measurements with all additional structures (AML, ALL, PLT, POL) the load on the ACL was reduced by 10% in tibial external rotation. CONCLUSION: This study showed that an additional anteromedial stabilization procedure secures the tibial external rotation and has the most protective effect on the ACL during these external rotational forces.

Hinge screw or no hinge stabilization provides decreased stability compared to hinge plate in a biomechanical evaluation of distal femoral derotational osteotomies.

PURPOSE: Derotational distal femoral osteotomy (DFO) is the causal treatment for patients with femoral torsional deformity. The fixation is achieved by a unilateral angle-stable plate. Delayed- or non-unions are one of the main risks of the procedure. An additional contralateral fixation may benefit the outcome. Therefore, we hypothesize that primary stability in DFO can be improved by an additional fixation with a hinge screw or an internal plate. METHODS: Derotational DFO was performed in 15 knees and fixed either with an angle-stable plate only (group 'None'), with an additional lateral screw (group 'Screw') or with an additional lateral plate (group 'Plate'). Biomechanical evaluation was carried out under axial loading of 150 N (partial weight bearing) and 800 N (full weight bearing), followed by internal and external rotation. After linear axial loading in step 1, a cyclic torsional load of 5 Nm was applied under constant axial load in step 2. In step 3, the specimens were unloaded. Micromovements between the distal and proximal parts of the osteotomy were recorded at each step for all specimens. RESULTS: In step 1, the extent of micromovements was highest in group 'None' and lowest in group 'Plate' without being significantly different. In step 2, group 'Plate' showed significantly higher stability, reflected by less rotation and lower micromovements. Increasing the axial load from 150 to 800 N at step 2 resulted in increased stability in all groups but only reached significance in group 'None'. CONCLUSION: An additional contralateral plate significantly increased stability in derotational DFO compared to the unilateral angle-stable plate only. Contrary, a contralateral hinge screw did not provide improved stability. STUDY DESIGN: Experimental study. LEVEL OF EVIDENCE: IV.

Comparison of 3T and 7T magnetic resonance imaging for direct visualization of finger flexor pulley rupture: an ex-vivo study.

OBJECTIVE: To compare image quality and diagnostic performance of 3T and 7T magnetic resonance imaging (MRI) for direct depiction of finger flexor pulleys A2, A3 and A4 before and after artificial pulley rupture in an ex-vivo model using anatomic preparation as reference. MATERIALS AND METHODS: 30 fingers from 10 human cadavers were examined at 3T and 7T before and after being subjected to iatrogenic pulley rupture. MRI protocols were comparable in duration, both lasting less than 22 min. Two experienced radiologists evaluated the MRIs. Image quality was graded according to a 4-point Likert scale. Anatomic preparation was used as gold standard. RESULTS: In comparison, 7T versus 3T had a sensitivity and specificity for the detection of A2, A3 and A4 pulley lesions with 100% vs. 95%, respectively 98% vs. 100%. In the assessment of A3 pulley lesions sensitivity of 7T was superior to 3T MRI (100% vs. 83%), whereas specificity was lower (95% vs. 100%). Image quality assessed before and after iatrogenic rupture was comparable with 2.74 for 7T and 2.61 for 3T. Visualization of the A3 finger flexor pulley before rupture creation was significantly better for 7 T (p < 0.001). Interobserver variability showed substantial agreement at 3T (κ = 0.80) and almost perfect agreement at 7T (κ = 0.90). CONCLUSION: MRI at 3T allows a comparable diagnostic performance to 7T for direct visualization and characterization of finger flexor pulleys before and after rupture, with superiority of 7T MRI in the visualization of the normal A3 pulley.

[Patient-specific cutting guides in corrective osteotomy near to the knee joint]. / Patientenspezifische Schnittblöcke bei kniegelenknahen Korrekturosteotomien.

OBJECTIVE: Patient-specific cutting guides (PSCG) are used in osteotomy near to the knee joint to simplify the operative technique, shorten the duration of surgery, reduce radiation exposure and to exactly realize the preoperative planning during surgery, especially when complex deformities are corrected simultaneously in multiple planes. INDICATIONS: The application of PSCG is in principle possible in all osteotomies near to the knee joint but is especially useful in multidimensional, complex osteotomy. CONTRAINDICATIONS: No specific contraindications. SURGICAL TECHNIQUE: After multidimensional 3D analysis and planning using a preoperative computed tomography (CT) protocol, a 3D-printed patient-specific cutting guide is produced. This PSCG is used during standard osteotomy near to the knee. Using this PSCG the guided sawcut and predrilling of the screw positions inside the bone for the screws of the planned angle stable osteotomy plate are performed. The amount of the deformity correction needed is "stored" in the PSCG and is converted to the bony geometry during placement of the screws in the predrilled holes through the plate after opening or closing the osteotomy. Apart from that, the surgical approach and technique are equivalent to the standard osteotomy types near to the knee. POSTOPERATIVE MANAGEMENT: The application of PSCG in osteotomy near to the knee does not change the postoperative management of the specific osteotomy. RESULTS: The use of patient-specific cutting guides leads to a higher accuracy in the implementation of the preoperative planning and the desired target axis is achieved with greater accuracy. Multidimensional complex corrections can also be exactly planned and implemented. In addition, the intraoperative radiation exposure for the operation team can possibly be reduced.

Refixation of the anterior cruciate ligament: A biomechanical analysis of suture techniques in a porcine model.

Purpose: Refixation of acute anterior cruciate ligament (ACL) tears represents an increasingly popular treatment option. Systematic evaluations of various suture technique parameters are still pending. We therefore aimed to evaluate the mechanical pull-out outcomes of various suture methods for optimization of ACL refixation. Methods: Sixty fresh knees from mature domestic pigs were dissected and the femoral attachment of the ACL was peeled off. The 60 knees were divided in 10 groups and sutured as follows: (A) one suture (1, 2, 4 and 6 passes), (B) two sutures (2, 4 and 6 passes each; sutures knotted together as a loop) and (C) two sutures (2, 4 and 6 passes each, sutures knotted separately). The pull-out test was conducted using a validated electrodynamic testing machine. First occurrence of failure, maximum pull-out load and stiffness were measured. Suture failure was defined as pull-out of the ACL. Results: Two-point fixation, using two sutures, with at least two passes, showed the most favourable biomechanical stability. The maximum pull-out load was significantly higher with two sutures (529.5 N) used compared to one (310.4 N), p < 0.001. No significant differences were found for maximum pull-out loads between two-point fixation versus one-point fixation but stiffness was significantly higher with two-point fixation (107.4 N/mm vs. 79.4 N/mm, p < 0.001). More passes resulted in higher maximum pull-out loads. Conclusion: The results suggest using two independent sutures, refixed separately and at least two suture passes, is appropriate for ACL refixation. More suture passes provide additional strength but are technically challenging to achieve during surgery. Level of Evidence: Level IV.

Vitamin E-enriched medium cross-linked polyethylene in total knee arthroplasty (VIKEP): clinical outcome, oxidation profile, and wear analysis in comparison to standard polyethylene-study protocol for a randomized controlled trial.

BACKGROUND: The gliding surface of total knee endoprostheses is exposed to high loads due to patient weight and activity. These implant components are typically manufactured from ultra-high molecular weight polyethylene (UHMWPE). Crosslinking of UHMWPE by ionizing radiation results in higher wear resistance but induces the formation of free radicals which impair mechanical properties after contact with oxygen. Medium-crosslinked UHMWPE enriched with vitamin E (MXE) provides a balance between the parameters for a sustainable gliding surface, i.e., mechanical strength, wear resistance, particle size, and oxidation stability. Therefore, a gliding surface for knee endoprostheses made up from this material was developed, certified, and launched. The aim of this study is to compare this new gliding surface to the established predecessor in a non-inferiority design. METHODS: This multicenter, binational randomized controlled trial will enroll patients with knee osteoarthritis eligible for knee arthroplasty with the index device. Patients will be treated with a knee endoprosthesis with either MXE or a standard gliding surface. Patients will be blinded regarding their treatment. After implantation of the devices, patients will be followed up for 10 years. Besides clinical and patient-related outcomes, radiological data will be collected. In case of revision, the gliding surface will be analyzed biomechanically and regarding the oxidative profile. DISCUSSION: The comparison between MXE and the standard gliding surface in this study will provide clinical data to confirm preceding biomechanical results in vivo. It is assumed that material-related differences will be identified, i.e., that the new material will be less sensitive to wear and creep. This may become obvious in biomechanical analyses of retrieved implants from revised patients and in radiologic analyses. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04618016. Registered 27 October 2020, https://clinicaltrials.gov/study/NCT04618016?term=vikep&checkSpell=false&rank=1 . All items from the World Health Organization Trial Registration Data Set can be found in Additional file 1.

"Run-and-jump failure": new injury patterns in indoor bouldering.

In recent years, professional and non-professional bouldering have seen a fundamental change in movement patterns towards complex movement sequences. This is associated with increased demands on the musculoskeletal system, especially the lower extremities, which can lead to new injury patterns. In the course of our clinical work, we have already seen an increasing number of lower extremity injuries after run-and-jump sequences, with a severe one being highlighted in this case report.

Evaluation of finger cartilage composition in recreational climbers with 7 Tesla T2 mapping magnetic resonance imaging.

Purpose: Sport climbing may lead to tissue adaptation including finger cartilage before apparent surface damage is detectable. The main aim was to assess finger cartilage composition with T2 mapping in young, active climbers and to compare the results to a non-climbers' collective. A secondary aim was to compare whether differences in cartilage T2 times are observed between older vs. younger volunteers. Methods and materials: 7 Tesla MRI of the fingers Dig.2-4 was performed using a multi-echo spin echo sequence. Manual segmentation of 3 ROIs at the metacarpal heads, 1 ROI at the base phalanx and 1 ROI at the proximal interphalangeal joint was performed. Included were 13 volunteers without history of trauma who are regularly performing climbing activities as a recreational sport (>20 h/month). These were age-matched with 10 control subjects not performing climbing activities. Results: Mean age was 32.4 years for the climbing group and 25.8 years for the controls. Mean T2 values for the 5 different ROIs were 42.2 ± 7.8 msec for climbers and 41.4 ± 6.8 msec for non-climbers. No significant differences were observed for T2 values between both groups. However, higher age had a significant impact on T2 values for all assessed ROIs (higher age 44.2 ± 9.5, younger age 32.9 ± 5.7, p = 0.001). Discussion: This study evaluated the cartilage composition of young, engaged climbers with a T2 mapping MRI technique with the purpose to depict early onset joint changes. No negative impact on cartilage composition due to the sport activity was found, whereas age-related effects on the cartilage seemed to be more prominent.

Wrist Injuries in Climbers.

BACKGROUND: Acute and chronic injuries to the wrist are among the most common sport-related complaints of climbing athletes but have not been extensively evaluated in this population. Therefore, it is important to categorize climbing injuries to the wrist, analyze risk factors, and assess treatment outcomes. PURPOSE: To evaluate the distribution, outcomes, and influencing factors of wrist injuries in climbers. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Climbing athletes with wrist injuries who presented to our specialized sports medical center over the course of 4 years (2017-2020) were selected. All had prospectively completed questionnaires including their climbing-specific background (years of training, climbing level, training methods, etc). Injuries were analyzed (International Climbing and Mountaineering Federation [UIAA] grade and diagnosis), and treatment methods and outcomes were retrospectively assessed with a minimum follow-up of 2 years. Parameters included the climbing score, visual analog scale for pain score, Patient-Rated Wrist Evaluation (PRWE) score, and shortened version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) score including the sport component (DASH-Sport) score before and after treatment as well as time to return to climbing. RESULTS: A total of 69 patients (25 female, 44 male) with 78 wrist injuries were identified and analyzed. Of these, 7 injuries were bilateral, occurring at the same time, and 2 injuries were independent reinjuries to either the same or the contralateral side. In addition, 24 injuries (30.8%) were acute, while 54 (69.2%) were chronic. Overall, 2 injuries had a UIAA grade of 3; all others had a UIAA grade of 2. The most frequent injuries were synovitis of the ulnocarpal recess, ulnar impaction, bone marrow edema of the lunate, wrist sprains (joint capsular pain with stress, with no pathological finding on magnetic resonance imaging), and wrist ganglion cysts. Nonoperative treatment was performed for 61 of the injuries, while 17 were treated surgically. In 51 cases (65.4%), injuries healed without consequences; in 27 cases (34.6%), discomfort remained. The visual analog scale pain score decreased from 4.8 ± 1.9 before treatment to 0.7 ± 1.0 after treatment (P < .001), the PRWE score decreased from 53.6 ± 24.9 to 10.3 ± 13.1 (P < .001), the QuickDASH score improved from 53.0 ± 16.6 to 20.0 ± 20.2 (P < .001), and the DASH-Sport score improved from 82.0 ± 16.1 to 38.1 ± 23.5 (P < .001). The climbing score improved from 2.5 ± 1.1 to 4.3 ± 1.0 points (P < .001). The patient-reported number of days with pain was negatively correlated with changes in the PRWE score (r = -0.351; P < .001), QuickDASH score (r = -0.316; P = .007), and climbing score (r = -0.264; P = .025) as well as the number of days without climbing (r = -0.266; P = .025). The number of days without climbing was positively correlated with changes in the PRWE score (r = 0.369; P < .001). CONCLUSION: Wrist injuries in climbers constituted a diverse set of diagnoses. Ulnar-sided injuries were most common, and many patients had >1 diagnosis. Outcomes for all treatment methods (surgery and nonoperative care) were favorable, but approximately one-third of climbers had persistent wrist discomfort after treatment, underscoring the need for accurate diagnoses and acute and expert care.

Epidemiology of Acute and Overuse Injuries in Underwater Rugby.

Background: Underwater rugby (UWR) is a team sport. Athletes require a high degree of strength, endurance, speed, and coordination involving intense physical contact. Currently, a paucity of literature exists regarding injury occurrence in UWR. Purpose: To examine the nature and prevalence of acute and overuse injuries in UWR. Study Design: Descriptive epidemiology study. Methods: Between November 2020 and March 2021, a total of 720 German UWR athletes were invited to take an online survey developed by orthopaedic specialists with UWR athletes. Data were recorded regarding general and health-related information, training habits, acute injuries that necessitated an interruption in training and/or doctor consultation, as well as overuse injuries. Overuse injuries were evaluated using the Oslo Sports Trauma Research Centre Overuse Injury Questionnaire. Statistical analyses included t tests or rank sum tests depending on normality of distribution. A nonparametric Kruskal-Wallis 1-way analysis of variance on ranks was used for nonnormally distributed data among several groups. Results: This study included 161 active athletes (mean ± SD, 36.1 ± 11.9 years old; 75.3% male) for analysis, of whom 90.1% were competing regularly. The performance-level distribution was as follows: first German national league (n = 73), second German national league (n = 46), state league (n = 17), district league (n = 1), and no league (n = 24). The mean ± SD sport-specific training workload was 5.6 ± 3.0 h/wk, including UWR training, additional swimming (n = 71; 44.1%), strength (n = 70; 43.5%), and/or endurance training (n = 102; 63.4%). Acute injuries were recorded in 78.9% of all athletes. The most typical locations for acute injuries were hand/finger (42.4%), head/face (concussion, ruptured eardrum; 18.1%), wrist (5.5%), or spine (5.0%). Overuse injuries were reported by 42.9% of the participants. The predominant locations for overuse injuries were hand/finger (18.8%), shoulder/clavicle (14.1%), spine and wrist (10.7% each), head/face (8.7%), and ankle joint and knee (6.7% each). Conclusion: In the current study, 3 of 4 athletes reported at least 1 acute injury, and 2 of 5 athletes reported at least 1 overuse injury. Leading injury regions were the hand/finger, head/ear, wrist, and spine.

Effects of exercise and cold-water exposure on microvascular muscle perfusion.

PURPOSE: Microvascular blood flow (MBF) and its intramuscular regulation are of importance for physiological responsiveness and adaptation. The quantifiable in-vivo monitoring of MBF after cycling or systemic cold-water exposure may reveal new insights into capillary regulatory mechanisms. This study aimed to assess the role of exercise and cold therapy on MBF by using contrast-enhanced ultrasound (CEUS). METHODS: Twenty healthy athletes were recruited and randomly assigned to an intervention (IG) or a control group (CG). MBF was quantified in superficial (rectus femoris, RF) and deep muscle layers (vastus intermedius, VI). Representative perfusion parameters (peak enhancement (PE) and wash-in area under the curve (WiAUC)) were measured after a standardized measurement protocol for both groups at resting conditions (t0) and after cycling (20 min., 70% Watt max, t1) for both groups, after cold-water immersion exposure for IG (15 min., 12°C) or after precisely 15 minutes of rest for CG (t2) and for both groups after 60 minutes of follow-up (t3). RESULTS: At t1, MBF in VI increased significantly compared to resting conditions in both groups in VI (p= 0.02). After the cold-water exposure (t2), there were no statistically significant changes in perfusion parameters as well as after 60 minutes of follow-up (t3) (p = 0.14). CONCLUSION: Cycling leads to an upregulation of MBF. However, cold exposure does not change the MBF. The implementation of CEUS during different physiological demands may provide deeper insight into intramuscular perfusion regulation and regenerative processes.

Functional and Sport-Specific Outcome Following Traumatic First-Time Shoulder Dislocation and Arthroscopic Surgical Repair in Rock Climbers.

INTRODUCTION: Traumatic shoulder dislocations rank among the most common shoulder injuries in climbers, with rising numbers over the last years. The objective of this study was to analyze the outcome following traumatic first-time shoulder dislocation and subsequent surgical treatment in this population. METHODS: In a retrospective study, climbers who experienced a traumatic shoulder dislocation were treated with an arthroscopic repair of the labrum-ligament complex (LLC). The functional outcome was assessed with a standardized questionnaire and clinical examination, including the Constant Murley and Single Assessment Numeric Evaluation scores. The sport-specific outcome was analyzed using the Union Internationale des Associations d'Alpinisme (UIAA) scale of difficulty and a sport-specific outcome score. RESULTS: The functional and sport-specific outcome for 27 climbers (20 men; 7 women; 3 with bilateral injuries; age, 34±11 [17-61] y; data presented as mean±SD [range]) was assessed 53±29 (12-103) mo after surgery. The postoperative Constant Murley score was 95±8 (67-100) points. At follow-up, 93% (n=25) of patients had started climbing again. Twenty-one climbers (78%) reached a climbing level within the range of ±0.33 UIAA grades of their initial capability or even exceeded their preinjury grade. Only 7% (n=2) of the patients had a recurrent shoulder dislocation, leading to a secondary surgery, and, therefore, required ongoing postoperative treatment at the time of follow-up. CONCLUSIONS: Arthroscopic repair of the LLC following first-time traumatic shoulder dislocation in climbers shows a good outcome and a low recurrence rate. After surgery, most patients are able to regain a high level of rock-climbing ability.

Intraoperative control by Schanz-screws is inaccurate to achieve the exact amount of correction in de-rotational osteotomies.

PURPOSE: The accuracy of intraoperative control of correction commonly is achieved by K-wires or Schanz-screws in combination with goniometer in de-rotational osteotomies. The purpose of this study is to investigate the accuracy of intraoperative torsional control in de-rotational femoral and tibial osteotomies. It is hypothesized, that intraoperative control by Schanz-screws and goniometer in de-rotational osteotomies around the knee is a safe and well predictable method to control the surgical torsional correction intraoperatively. METHODS: 55 consecutive osteotomies around the knee joint were registered, 28 femoral and 27 tibial. The indication for osteotomy was femoral or tibial torsional deformity with the clinical occurrence of patellofemoral maltracking or PFI. Pre- and postoperative torsions were measured according to the method of Waidelich on computed tomography (CT) scan. The scheduled value of torsional correction was defined by the surgeon preoperatively. Intraoperative control of torsional correction was achieved by 5 mm-Schanz-screws and goniometer. The measured values of torsional CT scan were compared to the preoperative defined and intended values and deviation was calculated separately for femoral and tibial osteotomies. RESULTS: The surgeon's intraoperative measured mean value of correction in all osteotomies was 15.2° (SD 4.6; range 10-27), whereas the postoperatively measured mean value on CT scan was 15.6 (6.8; 5.0-28.5). Intraoperatively the femoral mean value measured 17.9° (4.9; 10-27) and 12.4° (1.9; 10-15) for the tibia. Postoperatively the mean value for femoral correction was 19.8 (5.5; 9.0-28.5) and 11.3 (5.0; 5.0-26.0) for tibial correction. When considering a deviation of plus or minus 3° to be acceptable femorally 15 osteotomies (53.6%) and tibially 14 osteotomies (51.9%) fell within these limits. Nine femoral cases (32.1.%) were overcorrected, four cases undercorrected (14.3%). Four tibial cases of overcorrection (14.8%) and 9 tibial cases of undercorrection (33.3%) were observed. However, the observed difference between femur and tibia regarding the distribution of cases between the three groups did not reach significance. Moreover, there was no correlation between the extent of correction and the deviation from the intended result. CONCLUSION: The use of Schanz-screws and goniometer in de-rotational osteotomies as an intraoperative control of correction is an inaccurate method. Every surgeon performing derotational osteotomies must consider this and include postoperative torsional measurement in his postoperative algorithm until new tools or devices are available to guarantee a better intraoperative accuracy of torsional correction. STUDY DESIGN: Observational study. LEVEL OF EVIDENCE: III.

Constrained metal-on-metal hip arthroplasty: ever heard of a 50-year survival story?

BACKGROUND: The history of total hip arthroplasty dates back to the first half of the twentieth century. Data on hip endoprostheses implanted during the 1960s and 1970s suggest widely varying survival rates of the prosthesis. CASE: A case of a patient who underwent total hip arthroplasty in 1972 using a Sivash prosthesis, developed in 1956 in the former Soviet Union, is presented in this article. The prosthesis has remained unrevised in the patient's body for 50 years and he continues to be widely free of implant-related symptoms. Despite the constrained metal-on-metal design of the implant, which can lead to adverse reactions to metal debris, no elevated systemic metal ion levels were detected. CONCLUSION: The likelihood of encountering patients with prosthesis survival beyond 50 years is still rare. Nevertheless, changing demographics and the steadily improving designs and materials of hip endoprostheses may likely result in such cases.

The awareness of injury prevention programmes is insufficient among French- and German-speaking sports medicine communities in Europe.

PURPOSE: Evaluate the current state of sports injury prevention perception, knowledge and practice among sports medicine professionals located in Western Europe and involved in injury prevention. METHODS: Members of two different sports medicine organizations (GOTS and ReFORM) were invited to complete a web-based questionnaire (in German and in French, respectively) addressing perception, knowledge and implementation of sports injury prevention through 22 questions. RESULTS: 766 participants from a dozen of countries completed the survey. Among them, 43% were surgeons, 23% sport physicians and 18% physiotherapists working mainly in France (38%), Germany (23%) and Belgium (10%). The sample rated the importance of injury prevention as "high" or "very high" in a majority of cases (91%), but only 54% reported to be aware of specific injury prevention programmes. The French-speaking world was characterized by lower levels of reported knowledge, unfamiliarity with existing prevention programmes and less weekly time spent on prevention as compared to their German-speaking counterparts. Injury prevention barriers reported by the respondents included mainly insufficient expertise, absence of staff support from sports organizations and lack of time. CONCLUSION: There is a lack of awareness regarding injury prevention concepts among sports medicine professionals of the European French- and German-speaking world. This gap varied according to the professional occupation and working country. Relevant future paths for improvement include specific efforts to build awareness around sports injury prevention. LEVEL OF EVIDENCE: Level IV.

Determination of Standard Values for Knee Version in a Healthy Population.

BACKGROUND: Different measures are used to describe relevant anatomic variations that can result in patellofemoral instability and disorders. Knee version, the relative rotational alignment between the femur and tibia in the axial plane at the level of the knee, may have a decisive effect on the kinematics of the patellofemoral joint. However, data regarding the values of knee version are currently lacking. PURPOSE: This study aimed to determine standard values for knee version in a healthy population. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 100 healthy volunteers (50 male and 50 female) without patellofemoral disorders or lower extremity malalignment were included in this study and underwent knee magnetic resonance imaging. The torsion values of the femur and tibia were independently measured using the Waidelich and Strecker method. Knee version, defined as static rotation of the tibia with respect to the femur in full extension, was determined by measuring the angle between the tangent lines to the dorsal femoral condyle (DFC) and the dorsal tibial head (DTH; defined by the posterior point of the proximal tibial plateau). Supplementary measurements were obtained as follows: (1) femoral epicondylar line (FEL), (2) tibial ellipse center line (TECL), (3) tibial tuberosity-trochlear groove (TT-TG) distance, and (4) tibial tuberosity-posterior cruciate ligament (TT-PCL) distance. RESULTS: In 200 analyzed legs of 100 volunteers (mean age, 26.5 ± 5.8 years [range, 18 to 40 years]), we identified a mean internal femoral torsion of -23.8°± 9.7° (range, -46.2° to 1.6°), external tibial torsion of 33.2°± 7.4° (range, 16.4° to 50.3°), and external knee version (DFC to DTH) of 1.3°± 3.9° (range, -8.7° to 11.7°). Other measurements were as follows: FEL to TECL, -0.9°± 4.9° (range, -16.8° to 12.1°); FEL to DTH, -3.6°± 4.0° (range, -12.6° to 6.8°); and DFC to TECL, 4.0°± 4.9° (range, -12.7° to 14.7°). The mean TT-TG distance was 13.4 ± 3.7 mm (range, 5.3-23.5 mm), and the mean TT-PCL distance was 11.5 ± 3.5 mm (range, 6.0-20.9 mm). Female participants had significantly greater external knee version than male participants. CONCLUSION: Coronal- and sagittal-plane alignments of the knee have a well-known effect on the biomechanics of this joint. Additional information about the axial plane may result in new decision-making algorithms for managing knee disorders. This study is the first to report standard values of knee version in a healthy population. As a subsequent step building on this work, we advocate for the measurement of knee version in patients with patellofemoral disorders, as this parameter may assist with new treatment guidelines in the future.

Ski Mountaineering-Scientific Knowledge of This New Olympic Sport: A Narrative Review.

ABSTRACT: Ski mountaineering (skimo) has been accepted as a new sport for the 2026 Milan-Cortina Olympics. The equipment used in this competitive ski mountaineering varies from leisure ski mountaineering equipment mainly in one point: the minimal weight. At the elite athlete level, skimo demands both maximal endurance performance and a high-intensity anaerobic capacity for the sprint and vertical races. Race time significantly correlates to V˙O2max, body mass index and racing gear mass. Available literature only rarely comments on competitive skimo injuries. Injuries are not only due to falls in downhill skiing but also can result from external hazards, such as avalanches and cold. The high training load of athletes in combination with a low body weight, low body fat, and exposure to cold cause high rates of respiratory infections in athletes. The inclusion of skimo into the Olympic program is expected to result in certain changes, such as higher training loads for the athletes and increased scientific interest into training methods.

Dynamic study of the finger interphalangeal joint volar plate-motion analysis with magnetic resonance cinematography and histologic comparison.

OBJECTIVE: We aimed to further improve knowledge about volar plate (VP) motion of the finger proximal interphalangeal joint (PIP), by analyzing the dynamic VP shape during a full range of finger flexion using magnetic resonance cinematography of the fingers (MRCF), and to compare the results with anatomical cross sections from cadaver specimens. MATERIALS AND METHODS: The dynamic sagittal VP shape was visualized with MRCF in a total number of 23 healthy volunteers. The length, angle, and thickness as well as the contact length of the VP to the PIP joint base were measured. Statistical analysis included t-test or rank-sum testing. Anatomical cross sections with differing degrees of PIP joint flexion were obtained from 12 cadaver specimens (fingers) for comparison. RESULTS: Significant positive correlations between PIP joint flexion angle and VP area, length, depth and the VP contact length were found. This matched histologically to fiber rearrangements especially within the loose third VP layer. CONCLUSION: Our study analyzed the full range of motion dynamic VP shape of the PIP joint using MRCF. This contributes to a more precise understanding of the complex interaction of the VP with the PIP joint and may facilitate evaluation of clinical cases such as VP avulsion or pulley rupture.