The impact of the SARS-CoV-2 pandemic-related lockdowns on orthopedic trauma emergencies at a level-one trauma center.

INTRODUCTION: The SARS-CoV-2 pandemic and its associated lockdowns had a profound effect on orthopedic trauma emergencies. This study aimed to investigate the patient volume and injury patterns at a level-one trauma center during the SARS-CoV-2 pandemic and compare them to the pre-pandemic conditions. MATERIALS AND METHODS: A retrospective chart review of all patients who presented to the orthopedic trauma emergency department of a level-one trauma center in Cologne, Germany within a 2 year period from March 16th, 2019 to March 15th, 2020 (pre-pandemic control) and from March 16th, 2020 and March 15th, 2021 (pandemic) was performed. The pandemic year was separated into three periods: (1) first lockdown, (2) between lockdowns and (3) second lockdown. The absolute numbers of patient presentations, the Manchester triage score (MTS) and the relative proportion of patients with structural organ injuries, fractures and dislocations, of polytraumatized patients, of hospital admissions, of subsequent emergency or semi-elective surgeries and of work-related accidents were evaluated in comparison to the pre-pandemic control. RESULTS: A total of 21,642 patient presentations were included in this study. Significantly less weekly orthopedic trauma emergency patient presentations were recorded during the pandemic (p < 0.01). The MTS was significantly lower during the first lockdown and between lockdowns (p < 0.01). The proportional incidence of overall structural organ injuries, fractures and dislocations, of upper limb fractures/dislocations, of hospital admissions and of patients requiring surgery was significantly increased during the pandemic (p ≤ 0.03). The proportional incidence of work-related injuries was significantly decreased during the pandemic (p < 0.01). CONCLUSIONS: Orthopedic trauma emergency presentations were reduced during the SARS-CoV-2 pandemic. Due to the reluctancy of patients to visit the emergency department during the pandemic, the proportions of relevant injuries in general and of upper limb injuries in particular as well as of patients requiring hospital admission and trauma-related surgery were significantly increased.

The impact of knee arthrodesis on gait kinematics, muscle activity and patient-reported outcome.

BACKGROUND: The aim of this retrospective study was to analyze gait kinematicsandoutcome parameters after knee arthrodesis. METHODS: Fifteenpatients with a mean follow-up of 5.9 (range0.8-36) years after unilateral knee arthrodesis were included. A 3D gait analysis was performed and compared to a healthy control group of14patients. Comparative electromyography was performed bilaterally at the rectus femoris, vastuslateralis/medialisand tibialis anterior muscles. The assessment further included standardized outcome scores- Lower Extremity Functional Scale (LEFS) andShort Form Health Survey (SF-36). RESULTS: The 3D analysis showed a significantly shortened stance phase (p = 0.000), an extended swing phase (p = 0.000), and an increased time per step (p = 0.009) for the operated side compared with thenonoperatedside. There were statistically significant differences in the extent of movement of the hips, knees and ankles among the operated andnonoperatedsides and the control group. For the mean EMG measurement, no significant difference was found between the healthy control group and the patients with arthrodesis.The average LEFSscorewas 27.5 ± 10.6out of a maximum of 80 points,and the mean physical total scale and mean emotional total scale scores for the SF-36 were 27.9 ± 8.5and 52.9 ± 9.9, respectively. CONCLUSIONS: Arthrodesis of the knee joint causes significant kinematic changes in gait pattern,and patients achieve poor results in subjective and functional outcomes(SF- 36, LEFS).Arthrodesis ensures that the extremities are preserved and can enable walking, but it must be viewed as a severe handicap for the patient.

Influence of articular step-off on contact mechanics in fractures of the posterolateral-central tibial plateau - a biomechanical study.

BACKGROUND: The posterior quadrants of the tibial plateau are frequently involved in OTA type C tibial plateau fractures. The biomechanical influence of a residual articular step-off of the posterolateral-central (PLC) segment, which is difficult to visualize intraoperatively, remains unclear. Therefore, aim of this study was to investigate the contact area and stress of the tibial plateau in cases of different articular step-offs of the PLC segment. METHODS: Seven human cadaveric knees were used to simulate articular impressions of the PLC segment with step-offs of 1 mm, 3 mm, and 5 mm. The knees were axially loaded up to 150 N during a total of 25 dynamic cycles of knee flexion up to 90°. Pressure mapping sensors were inserted into the medial and lateral joint compartments beneath the menisci to measure articular contact area and stress. RESULTS: Between 60° and 90° of knee flexion, increasing PLC segment impressions of the tibial plateau led to increasing contact stress and a significantly reduced contact area. The largest decrease in the contact area was 30 %, with an articular step-off of 5 mm (0.003). An increase in contact stress, especially from a 3-mm step-off, was measured, with a doubling of the mean contact stress at 3-mm and 5-mm step-offs and 90° knee flexion (p = 0.06/0.05). CONCLUSION: From a biomechanical point of view, posterior impressions of the PLC segment greater than a 1-mm step-off should be addressed as anatomically as possible, especially in active patients with the need for higher knee flexion angles.

Factors influencing the outcome after surgical reconstruction of OTA type B and C tibial plateau fractures: how crucial is the restoration of articular congruity?

INTRODUCTION: Only few and inconsistent data about the impact of articular congruity and tolerable residual intraarticular steps and gaps of the joint surface after tibial plateau fractures exist. Therefore, aim of this study was to investigate the correlation between OTA type B and C tibial plateau fracture outcomes and postoperative articular congruity using computed tomography (CT) data. MATERIALS AND METHODS: Fifty-five patients with a mean age of 45.5 ± 12.5 years and treated for 27 type B and 28 C tibial plateau fractures with pre- and postsurgical CT data were included. Primary outcome measure was the correlation of postoperative intraarticular step and gap sizes, articular comminution area, the postoperative medial proximal tibial angle (MPTA), and the Lysholm and IKDC score. Receiver-operating characteristic (ROC) curves were used to determine threshold values for step and gap heights according to the following outcome scores: IKDC > 70; Lysholm > 80. Secondary outcome measures were the correlation of fracture severity, the number of complications and surgical revisions and the outcome scores, as well as the Tegner activity score before injury and at final follow-up. RESULTS: After a mean follow-up of 42.4 ± 18.9 months, the mean Lysholm score was 80.7 ± 13.3, and the mean IKDC score was 62.7 ± 17.6. The median Tegner activity score was 5 before the injury and 4 at final follow-up (p < 0.05). The intraarticular step height, gap size, comminution area and MPTA deviation were significantly negatively correlated with the IKDC and Lysholm scores. The cutoff values for step height were 2.6 and 2.9 mm. The gap size threshold was 6.6 mm. In total, an average of 0.5 ± 0.8 (range 0-3) complications occurred, and on average, 0.5 ± 1.1 (range 0-7) surgical revisions had to be performed. The number of complications and surgical revisions also had negative impacts on the outcome. Neither fracture severity nor BMI or patient's age was significantly correlated with the IKDC or Lysholm score. CONCLUSIONS: Tibial plateau fractures are severe injuries, which lead to a subsequent reduced level of patient activity. Precise reconstruction of the articular surface with regard to intraarticular step and gap size, residual comminution area and joint angle is decisive for the final outcome. Complications and surgical revisions also worsen it. LEVEL OF EVIDENCE: III.

[Augmented primary sutures "internal bracing" following ligamentous elbow dislocation]. / Augmentierte Primärnaht "internal bracing" nach ligamentärer Ellenbogenluxation.

OBJECTIVE: Aim of surgical treatment is the primary stabilization of the unstable elbow following a ligamentous elbow dislocation. INDICATIONS: Ligamentous elbow dislocations are typically accompanied by injuries to the surrounding musculature and collateral ligaments of the elbow joint. Surgical treatment is indicated in case of failure of nonoperative therapy, i.e., when a dislocation can only be prevented in immobilization > 90° and pronation of the elbow or an active muscular centering of the elbow fails after 5-7 days. CONTRAINDICATIONS: Contraindications for a solely "internal bracing" augmented primary suture are generally in the case of accompanying bony injuries in elbow dislocations, extensive soft-tissue injuries, and septic arthritis of the elbow. SURGICAL TECHNIQUE: The augmented primary suture of the elbow is performed using both a lateral (Kocher or Kaplan) and medial (FCU split) approach to the elbow. After reduction of the elbow, the collateral ligaments are first augmented with high-strength polyethylene suture and fixed in the distal humerus together with another high-strength polyethylene augmentation suture. The extensors and flexors are then fixed to the medial and lateral epicondyle, respectively, using suture anchors. POSTOPERATIVE MANAGEMENT: The aim of the postoperative management is early functional exercise of the elbow. The elbow is placed in an elbow brace to avoid varus and valgus load. RESULTS: Between August 2018 and January 2020, a total of 12 patients were treated with an augmented primary suture following unstable ligamentous elbow dislocation. After a mean follow-up of 14 ± 12.7 months, the mean Mayo Elbow Performance Score was 98.5 points with a mean functional arc of 115°. None of the patients reported a recurrent dislocation or persistent instability of the elbow.

Shoulder complaints and incidence of shoulder pathologies after contralateral major amputation in the mid and long-term.

INTRODUCTION: Amputations of the upper extremity are rare but present a life-altering event that is accompanied with considerable restrictions for the affected patients. Even with functional prosthesis, tasks of the amputated limb are usually transferred to the unaffected arm which could result in complaints of the unaffected shoulder in the mid and long term. We therefore aimed to investigate musculoskeletal pain and morphological degenerative changes of the shoulder following a contralateral amputation. MATERIALS AND METHODS: We included all patients with a major amputation treated at our institution with a minimum of three years since the amputation. All patients received an MRI of both shoulders and were investigated using validated scores for the upper extremity and physical activity (SSV, ASES, DASH, GPAQ, SF-36). Results of the MRIs were investigated for morphological changes by two blinded investigators comparing the side of the amputation and the unharmed upper extremity and results were correlated to the time since amputation and their physical activity. RESULTS: A total of 20 patients with a mean age of 56 ± 19.9 years (range, 23-82 years) could be included in the study. The mean time since the amputation was 26.3 ± 19 years (range, 3-73 years). On the unharmed upper extremity, the mean SSV was 61.9 ± 24.6, the mean ASES-Score 54.5 ± 20.3, the Constant-score of 63.7 ± 40.4 and a DASH-score of 47.6 ± 23.8. The MRI of the unharmed shoulder showed significant more full-thickness rotator cuff tears and joint effusion compared to the side of the amputation. Significant differences in the degree of a glenohumeral arthritis, AC-joint arthritis, or partial rotator cuff tears could not be found between shoulders. CONCLUSION: Amputations of the upper extremity are associated with a high disability of the unharmed upper extremity and more full thickness rotator cuff tears compared to the side of the amputation. However, the small number of patients and rotator cuff injuries should be kept in mind when interpreting the data. LEVEL OF EVIDENCE: IV (retrospective case series).

Monteggia fractures and Monteggia-like-lesions: a systematic review.

Monteggia injuries are rare, but severe injuries of the elbow including various injury patterns. Treatment of these injuries is still topic of debate and strategies differ widely. In this systematic review on Monteggia injuries in adults, we aimed to clarify the incidence of different injury patterns within Monteggia injuries, investigate the main reasons leading to revision surgery and explore which surgical treatments should be favored to achieve satisfactory clinical results.We initially identified 182 publications and ultimately included 17 retrospective studies comprising 651 cases. All patients were classified using the Bado classification, leading to 30.5% Bado type I fractures, 60.4% type II fractures, 5.1% type III and 3.1% type IV fractures. Mean revision rate was 23%. Ulna non-union (28%) and limited range-of-motion (22%) are the main reasons for revision surgery. Meta-analysis shows a trend toward the use of locking plates for ulna fixation which may lead to less revision surgery and fewer ulna non-unions. Further biomechanical and clinical research is necessary to clarify the role of radial head surgery.

The automized fracture edge detection and generation of three-dimensional fracture probability heat maps.

With proven impact of statistical fracture analysis on fracture classifications, it is desirable to minimize the manual work and to maximize repeatability of this approach. We address this with an algorithm that reduces the manual effort to segmentation, fragment identification and reduction. The fracture edge detection and heat map generation are performed automatically. With the same input, the algorithm always delivers the same output. The tool transforms one intact template consecutively onto each fractured specimen by linear least square optimization, detects the fragment edges in the template and then superimposes them to generate a fracture probability heat map. We hypothesized that the algorithm runs faster than the manual evaluation and with low (< 5 mm) deviation. We tested the hypothesis in 10 fractured proximal humeri and found that it performs with good accuracy (2.5 mm ± 2.4 mm averaged Euclidean distance) and speed (23 times faster). When applied to a distal humerus, a tibia plateau, and a scaphoid fracture, the run times were low (1-2 min), and the detected edges correct by visual judgement. In the geometrically complex acetabulum, at a run time of 78 min some outliers were considered acceptable. An automatically generated fracture probability heat map based on 50 proximal humerus fractures matches the areas of high risk of fracture reported in medical literature. Such automation of the fracture analysis method is advantageous and could be extended to reduce the manual effort even further.

Locking the Taylor Spatial Frame - The effect of three additional longitudinal rods on osteotomy site movements.

BACKGROUND: In clinical practice, even when the fixator is locked, a noticeable laxity of the construct can be observed. This study was designed to measure the stiffness of the fixator and to analyze the movements of the osteotomy site. Furthermore, the effect of three additional longitudinal rods on the locking of the construct was analyzed. METHODS: Five synthetic tibia/fixator models (Model A) were tested under rotational torque (40 Nm) and axial compression (700 N). Three additional rigid rods were subsequently mounted, and the tests were repeated (Model B). The movements of the fixator as well as the osteotomy site were registered by a digital optical measurement system. Load- deformation curves, and so stiffness of the models, were calculated and compared. FINDINGS: Under rotational and axial loadings, Model A was found to be less rigid than Model B (p = 0.034; p = 0.194). Notably, Model A showed a region of laxity around neutral rotational (ΔF = 5 Nm) and axial (ΔF = 16.64 N) loading before a linear deformation trend was measured. Concomitantly, greater osteotomy site movement was measured for Model A than for Model B under full loading (p = 0.05) and within the region of increased laxity (p = 0.042). INTERPRETATION: The fixator showed an element of laxity around neutral axial and rotational loading, which transferred to the bone and led to a notable amount of osteotomy gap movement. Mounting three additional rods increased the stiffness of the construct and therefore reduced the movement of the osteotomy site.

The Use of the Ilizarov Fixator for the Treatment of Open and Closed Tibial Shaft and Distal Tibial Fractures in Patients with Complex Cases.

INTRODUCTION: Open and closed fractures of the tibial shaft or distal tibia can be challenging for surgeons to treat if the fractures are accompanied by aggravating conditions, such as various accompanying diseases, pronounced soft tissue injuries, osteomyelitis, and/or noncompliance. The aim of this retrospective study was to present our approach and results with the Ilizarov fixator as a treatment option for such individually complex cases. MATERIALS AND METHODS: Between 2005 and 2018, 20 patients were treated with the Ilizarov fixator for fractures of the tibial shaft/distal tibia. The indication for this was a 2nd- to 3rd-degree open fracture in 10 patients, a 1st-degree open fracture in one patient, and closed fractures in 9 patients. Aggravating conditions included soft tissue injuries, osteomyelitis, leg deformities, multiple traumas, smoking, alcohol/drug abuse, and obesity (BMI > 60). In addition to demographic data, the time of fixator treatment, complications, and the endpoint of consolidation were evaluated retrospectively. RESULTS: The mean time of fixator treatment was 29 (range 15-65) weeks. Complete fracture consolidation was achieved in 13 patients (65%) with the Ilizarov fixator. The mean follow-up period after fixator removal was 36 (range 2-186) months in 14 patients. Five patients with complete consolidation were lost to further follow-up. One patient was amputated. In six patients without union, internal osteosynthesis was carried out. CONCLUSION: The use of the Ilizarov fixator is a treatment option for individual high-risk patients with complicating courses but should be seen as a salvage procedure due to the high complication rate and long treatment process.

Injuries to the Coronoid Process of the Ulna with Involvement of the Lesser Sigmoid Notch.

INTRODUCTION: This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch. MATERIAL AND METHODS: Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients < 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured. RESULTS: Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm. CONCLUSION: Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.

Analysis of bone transport for ankle arthrodesis as a limb salvage procedure for the treatment of septic pilon fracture nonunion.

Septic nonunion of the pilon region with ankle joint infection is challenging for orthopedic surgeons to treat and is associated with a high risk of limb loss. Therefore, the aim of this study was to evaluate the effectiveness of bone transport for ankle arthrodesis in salvaging the limp after septic ankle destruction of the pilon region. We conducted a single-center, retrospective study including 21 patients treated for septic pilon nonunion with accompanying septic ankle destruction via Ilizarov bone transport between 2004 and 2018. In all cases, the complete excision of the nonunion and the resection of the ankle joint were carried out, followed by treating the bone and joint defect with a bone transport into the ankle arthrodesis. In 12/21 patients an additional flap transfer was required due to an accompanying soft tissue lesion. The overall healing and failure rate, final alignment and complications were recorded by the patients' medical files. The bone-related and functional results were evaluated according to the Association for the Study and Application of Methods of Ilizarov (ASAMI) scoring system and a modified American Orthopedic Foot and Ankle Society (AOFAS) scale. After a mean follow-up of 30.9 ± 15.7 months (range 12-63 months), complete bone and soft tissue healing occurred in 18/21 patients (85.7%). The patients had excellent (5), good (7), fair (4), and poor (3) results based on the ASAMI functional score. Regarding bone stock, 6 patients had excellent, 7 good, and 6 fair results. The modified AOFAS score reached 60.6 ± 18 points (range, 29-86). In total, 33 minor complications and 28 major complications occurred during the study period. In 2 cases, a proximal lower leg amputation was performed due to a persistent infection and free flap necrosis with a large soft tissue defect, whereas in one case, persistent nonunion on the docking side was treated with a carbon orthosis because the patient refused to undergo an additional surgery. Bone transport for ankle arthrodesis offers the possibility of limb salvage after septic ankle destruction of the pilon region, with acceptable bony and functional results. However, a high number of complications and surgical revisions are associated with the treatment of this severe complication after pilon fracture.

Anatomical repair and ligament bracing of Schenck III and IV knee joint dislocations leads to acceptable subjective and kinematic outcomes.

PURPOSE: The aim of this study was to analyze the outcomes of anatomical repair and ligament bracing for Schenck III and IV knee dislocation (KD). METHODS: The results of 27 patients (15 and 12 cases of Schenck III and IV KD, respectively) after a mean follow-up of 18.1 ± 12.1 months (range 6-45 months) were retrospectively reviewed. Twenty-two patients suffered high-kinetic-energy accidents, whereas five patients suffered ultralow-velocity (ULV) trauma due to obesity. The outcome measures were the Lysholm score, Hospital for Special Surgery (HSS) knee score, Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Short Form 36 (SF-36) score. A kinematic 3D gait analysis with five walking trials was performed to compare the patients and healthy controls. RESULTS: The mean KSS, HSS score, Lysholm score, and KOOS were 77.4 ± 14.4, 84.6 ± 11.2, 81.5 ± 10.4, and 67.3 ± 16.8, respectively. No intra- or postoperative complications occurred. The mean range of motion deficiency compared to the healthy side was 24.4 ± 18.5°. Ten patients had first-degree residual laxity of the anterior cruciate ligament; 12 and 2 patients had first- and second-degree residual laxity of the collateral ligament, respectively. Five patients underwent additional arthroscopic arthrolysis due to arthrofibrosis at an average of 6.2 ± 1.9 months (range 4-9 months) after the initial surgery. The 3D gait analysis showed no major differences in joint stability or movement between the patients and healthy controls. Only the ULV trauma patients had significantly lower outcome scores and showed larger kinematic deviations in joint movement during the gait analysis. CONCLUSION: Anatomical repair with ligament bracing is a suitable surgical procedure in the treatment of KD and provides evidence in clinical practice with the benefit of early, definitive repair and preservation of the native ligaments. Patients reach acceptable subjective and objective functional outcomes, including mainly normalized gait patterns during short-term follow-up, with only minor changes in kinematics and spatial-temporal characteristics. Obese patients who suffered ULV trauma showed significantly inferior outcomes with larger deviations in joint kinematics. LEVEL OF EVIDENCE: Level III.

Long-term follow up of extensor tendon ruptures of the knee using electromyography and three-dimensional gait analysis.

BACKGROUND: The aim of this study was to analyze the long-term outcomes of extensor tendon ruptures of the knee using exact measuring tools. METHODS: The results of patients treated for extensor tendon rupture with a minimum follow up of 10 years were reviewed. Electromyography (EMG) and three-dimensional (3D) gait analyses were performed and compared with the healthy side of each patient and with the gait patterns of 20 healthy controls. Functional outcome scores were assessed using the Lysholm score and Knee Injury and Osteoarthritis Outcome Score (KOOS). RESULTS: After a mean of 13.4 ± 3 years, 23 patients were available for follow up. The mean Lysholm score was 86.6, and the KOOS averaged 78.1. Gait analysis showed no major kinematic differences between these patients compared with healthy controls. In the squat test, the mean peak amplitude of the rectus femoris muscle was significantly smaller on the injured side than on the healthy side (140.21 ± 66.13 µV vs. 168.25 ± 91.77 µV; P = 0.01). The mean peaks of the vastus lateralis and medialis EMG signals were also lower on the injured side (P = 0.63; P = 0.08). Correspondingly, the thigh girth at 20 cm and 10 cm above the knee was significantly lower on the injured side. One patient had re-rupture after patella tendon repair. CONCLUSION: At long-term follow up the patients reached good clinical outcomes and exhibited mainly physiological gait patterns after rupture of knee extensor tendons. However, the thigh muscles showed hypotrophy and a significantly smaller EMG signal amplitude during a high-intensity task on the formerly injured side.

Ilizarov bone transport using an intramedullary cable transportation system in the treatment of tibial bone defects.

INTRODUCTION: Segmental tibia defects remain challenging for orthopedic surgeons to treat. The aim of this study was to demonstrate bone-related and functional outcomes after treatment of complex tibial bone defects using Ilizarov bone transport with a modified intramedullary cable transportation system (CTS). PATIENTS AND METHODS: We conducted a single-center, retrospective study including all 42 patients treated for tibial bone loss via Ilizarov bone transport with CTS between 2005 and 2018. Bone-related and functional results were evaluated according to the Association for the Study and Application of Methods of Ilizarov (ASAMI) scoring system. Complication and failure rates were determined by the patients' medical files. RESULTS: Patients had a mean age of 45.5 ± 15.1 years. The mean bone defect size was 7.7 ± 3.4 cm, the average nonunion scoring system (NUSS) score was 59 ± 9.5 points, and the mean follow-up was 40.8 ± 24.4 months (range, 13-139 months). Complete bone and soft tissue healing occurred in 32/42 patients (76.2%). These patients had excellent (10), good (17), fair (2), and poor (3) results based on the ASAMI functional score. Regarding bone stock, 19 patients had excellent, 10 good, and 3 fair results. In total, 37 minor complications and 62 major complications occurred during the study. In 7 patients, bone and soft tissue healing occurred after CTS failure with either an induced membrane technique or classic bone transport; 3 patients underwent lower leg amputation. Patients with treatment failure were significantly older (57.6 vs. 41.8 years; p = 0.003). Charlson score and treatment failure had a positive correlation (Spearman's rho 0.43; p = 0.004). CONCLUSION: Bone transport using both intramedullary CTS and Ilizarov ring fixation is viable for treating patients with bone loss of the tibia and complex infection or soft tissue conditions. However, a high number of complications and surgical revisions are associated with the treatment of this severe clinical entity and should be taken into account.

Biomechanical comparison of screw osteosyntheses and anatomical plating for coronoid shear fractures of the ulna.

INTRODUCTION: Among the few techniques described for the treatment of coronoid fractures, osteosynthesis techniques include screw osteosynthesis from anterior to posterior (AP) or from posterior to anterior (PA) and plate osteosynthesis. The aim of this study was to test the biomechanical stability of screw osteosynthesis and plate osteosynthesis using anatomical plates in coronoid process fractures. MATERIALS AND METHODS: On a total of 25 biomechanical synthetical ulnae, a coronoid shear fracture including 70% of the coronoid height was simulated. Osteosynthesis was then performed using two 2.7 mm screws from anterior, posterior and with use of three different anatomical plates of the coronoid process. For the biomechanical testing, axial load was applied to the fragment with 1000 cycles from 5 to 250 N, load to failure and load at 100 µm displacement. Displacements were measured using a point-based three-dimensional motion analysis system. RESULTS: Osteosynthesis using the PA-screw showed significant more displacement during cyclic loading compared with all other osteosyntheses (0.99 mm), whereas AP-screw showed the smallest displacement (0.10 mm) during cyclic loading. The PA-screw technique showed a significant lower load to failure compared to all other osteosynthesis with the highest load in AP-screw osteosynthesis. The load for 100 µm displacement was the smallest in PA-screw with a significant difference to the AP-screw and one plate osteosynthesis. CONCLUSION: Osteosynthesis of large coronoid shear fractures with two small-fragment screws from anterior allows stable fixation that is not inferior to anterior plate osteosynthesis and might be an alternative in specific fracture types. Posterior screw fixation was found as the weakest fixation method. LEVEL OF EVIDENCE: Basic science study.

Treatment of aseptic nonunion after medial opening-wedge high tibial osteotomy.

BACKGROUND: Nonunion after medial opening-wedge high tibial osteotomy (OWHTO) is a rare but serious complication with very limited data regarding its treatment. The aim of this study was to analyze the healing rate after operative treatment of nonunion after OWHTO. METHODS: We performed a single-center, retrospective study that included 14 patients with nonunion after OWHTO between 2010 and 2018. The treatment for all patients consisted of local debridement and cancellous bone grafting at the osteotomy gap. Revision osteosynthesis due to a loss of correction/loosening of the locking screws or plates was performed in 5 patients. In 7 patients, lateral hinge fractures were treated with additional lateral plating. Union was confirmed using the modified "Radiographic Union Score for Tibial fractures". Outcome measure was the Lysholm Knee Score at final follow-up. RESULTS: The mean age of the patients included in our study was 48.4 ± 6.7 years. Three patients were female (21.4%). The mean follow-up period was 20.8 ± 12.8 months. Union was achieved in 12/14 patients (85.7%) after a mean of 6 months (range, 3-13). The mean Lysholm Knee Score at the final follow-up was 83.2 ± 11.6. Two patients did not reach definitive union during the follow-up. In one patient, an infection of the nonunion following bone grafting was successfully treated with a two-stage procedure. Two patients needed additional cancellous bone grafting 6 and 8 months after the first revision surgery. All patients showed pain-free full weight bearing after union was achieved. CONCLUSIONS: Nonunions after OWHTO can generally be treated successfully with cancellous bone grafting. For patients who have loss of correction, loosening of the osteosynthetic material or fracture of the lateral hinge, an additional revision or additive osteosynthesis may be required. LEVEL OF EVIDENCE: Grade III.

Fractures around the hip: inducing life-like fractures as a basis for enhanced surgical training.

INTRODUCTION: In this study we investigated if realistic fracture patterns around the hip can be produced on human cadaveric specimens with intact soft tissue envelope. Possible applications of such fractured specimens would be in surgical training. MATERIALS AND METHODS: 7 cadaveric specimens (2 male, 5 female, 2 formalin-fixed, 5 fresh-frozen) were fractured. 2 specimens were fractured on both femurs, 5 only on one side, resulting in 9 fractures total. 5 fractures were set in our custom-made drop-test bench, 2 fractures by inducing axial force using a hammer, and the remaining 2 fractures by a direct dorsal approach and a chisel. AO/OTA and Pauwels classification were used to classify the fractures on the specimens by two independent trauma surgeons. RESULTS: In our drop-test bench, axial load with the femur adducted by 10° resulted in an intertrochanteric fracture (AO type A1.3), adducted by 20° resulted in a femoral neck fracture (Pauwels type III). Fracture induction using a hammer resulted in two intertrochanteric fractures (AO type A2.2 right, A3.3 left). The use of a chisel resulted in both cases in a femoral neck fracture. The acetabulum could be fractured multifragmentarily through use of a hemiprosthesis as a stamp. CONCLUSION: A high energetic impulse induced by a custom-made drop-test bench can successfully simulate realistic proximal femur and acetabular fractures in cadaveric specimens with intact soft tissue. Furthermore, axial load using a hammer as well as using a chisel through a direct dorsal approach represent additional methods for fracture induction. These pre-fractured specimens can be utilized in surgical education to provide a realistic teaching experience for specialized trauma education courses.

Osteosynthesis of Phalangeal Fractures: Biomechanical Comparison of Kirschner Wires, Plates, and Compression Screws.

PURPOSE: The aim of this study was to compare several osteosynthesis techniques (intramedullary headless compression screws, T-plates, and Kirschner wires) for distal epiphyseal fractures of proximal phalanges in a human cadaveric model. METHODS: A total of 90 proximal phalanges from 30 specimens (index, ring, and middle fingers) were used for this study. After stripping off all soft tissue, a transverse distal epiphyseal fracture was simulated at the proximal phalanx. The 30 specimens were randomly assigned to 1 fixation technique (30 per technique), either a 3.0-mm intramedullary headless compression screw, locking plate fixation with a 2.0-mm T-plate, or 2 oblique 1.0-mm Kirschner wires. Displacement analysis (bending, distraction, and torsion) was performed using optical tracking of an applied random speckle pattern after osteosynthesis. Biomechanical testing was performed with increasing cyclic loading and with cyclic load to failure using a biaxial torsion-tension testing machine. RESULTS: Cannulated intramedullary compression screws showed significantly less displacement at the fracture site in torsional testing. Furthermore, screws were significantly more stable in bending testing. Kirschner wires were significantly less stable than plating or screw fixation in any cyclic load to failure test setup. CONCLUSIONS: Intramedullary compression screws are a highly stable alternative in the treatment of transverse distal epiphyseal phalangeal fractures. Kirschner wires seem to be inferior regarding displacement properties and primary stability. CLINICAL RELEVANCE: Fracture fixation of phalangeal fractures using plate osteosynthesis may have the advantage of a very rigid reduction, but disadvantages such as stiffness owing to the more invasive surgical approach and soft tissue irritation should be taken into account. Headless compression screws represent a minimally invasive choice for fixation with good biomechanical properties.