Intraoperative dynamics of workflow disruptions and surgeons' technical performance failures: insights from a simulated operating room.

INTRODUCTION: Flow disruptions (FD) in the operating room (OR) have been found to adversely affect the levels of stress and cognitive workload of the surgical team. It has been concluded that frequent disruptions also lead to impaired technical performance and subsequently pose a risk to patient safety. However, respective studies are scarce. We therefore aimed to determine if surgical performance failures increase after disruptive events during a complete surgical intervention. METHODS: We set up a mixed-reality-based OR simulation study within a full-team scenario. Eleven orthopaedic surgeons performed a vertebroplasty procedure from incision to closure. Simulations were audio- and videotaped and key surgical instrument movements were automatically tracked to determine performance failures, i.e. injury of critical tissue. Flow disruptions were identified through retrospective video observation and evaluated according to duration, severity, source, and initiation. We applied a multilevel binary logistic regression model to determine the relationship between FDs and technical performance failures. For this purpose, we compared FDs in one-minute intervals before performance failures with intervals without subsequent performance failures. RESULTS: Average simulation duration was 30:02 min (SD = 10:48 min). In 11 simulated cases, 114 flow disruption events were observed with a mean hourly rate of 20.4 (SD = 5.6) and substantial variation across FD sources. Overall, 53 performance failures were recorded. We observed no relationship between FDs and likelihood of immediate performance failures: Adjusted odds ratio = 1.03 (95% CI 0.46-2.30). Likewise, no evidence could be found for different source types of FDs. CONCLUSION: Our study advances previous methodological approaches through the utilisation of a mixed-reality simulation environment, automated surgical performance assessments, and expert-rated observations of FD events. Our data do not support the common assumption that FDs adversely affect technical performance. Yet, future studies should focus on the determining factors, mechanisms, and dynamics underlying our findings.

"High ankle block" for surgery at the ankle joint.

BACKGROUND: Surgery around the ankle is increasingly embedded in outpatient treatment concepts. Unfortunately, the classic "ankle block" as a concept of regional anesthesia is inappropriate for surgery around the ankle because the injection sites are too distal to block this specific region. METHODS: The "high ankle block" avoids this disadvantage by dislocating the injection points 15 cm proximal to the malleoli. Three of five peripheral nerves necessary to perform the block can be reached by a circumferential subcutaneous wall. The Posterior Tibial Nerve and the Deep Peroneal Nerve are addressed by an ultrasound guided approach. RESULTS: The efficacy of the technique is highlighted by a case series (3 cases) in which the new blockade was used as a stand-alone procedure, i.e. without additional general anesthesia. CONCLUSIONS: The "high ankle block" may serve as an ultrasound guided expansion to the classic techniques, extending the operative spectrum to the ankle region.

Anatomical and biomechanical evaluation of the lateral calcaneo-cuboid and bifurcate ligaments.

BACKGROUND: This study aims to analyze the ligaments of the dorso-lateral calcaneo-cuboid joint and to assess the biomechanical relevance of the bifurcate ligament. METHODS: 16 specimens were analyzed for their ligamentous anatomy of the dorso-lateral calcaneo-cuboid joint and side-alternating assigned to two groups with varying ligamentous dissection order. The Chopart joint was stressed in plantar, medial, and lateral direction measuring the displacement by an 3D motion tracker for every dissection step. RESULTS: 37.5% of specimens had all ligaments (lateral calcaneo-cuboid, dorsal calcaneo-cuboid, bifurcate calcaneo-cuboid, bifurcate calcaneo-navicular), 37.5% were lacking bifurcate´s calcaneo-cuboid-portion, and 25% presented without dorsal calcaneo-cuboid. Biomechanical testing revealed no significant displacement within the calcaneo-cuboid or talo-navicular joint for any stressed state except for axial compression with dissected dorsal talo-navicular joint capsule in Group 2. CONCLUSION: Broad morphological variability and missing significant displacement regardless of its integrity, make the bifurcate ligament appear of limited biomechanical relevance.

Arthroscopically Assisted Treatment of Complex Ankle Fractures: Intra-articular Findings and 1-Year Follow-Up.

Especially after complex ankle fractures, patients regularly suffer from residual symptoms, presumably due to occult intra-articular injuries. The aim of this study was to evaluate the intra-articular lesions, identify fractures specifically at risk for these, and assess the results after arthroscopically assisted open reduction and internal fixation of complex ankle fractures after 1 year. The primary outcome was the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot score. Secondary outcome parameters were the Olerud and Molander Ankle Score (OMAS), Tegner activity scale, arthroscopic findings, functional assessment, and complications. Thirty-two patients (56% female) were enrolled. Chondral lesions were detected in 91%. Full-thickness lesions treated by microfracturing were observed in 0% of unimalleolar, 43% of bimalleolar, and 40% of trimalleolar fractures. After 1 year, the median (interquartile range) AOFAS was 94 (9) and OMAS was 90 (10) for all patients. When analyzing factors possibly influencing the outcome, age, sex, smoking, grading for surgical procedures according to the American Society of Anesthesiologists, fracture type (uni-, bi-, or trimalleolar), severity of chondral lesions graded according to the International Cartilage Repair Society (grade <4 versus grade 4), and syndesmotic instability had no significant influence on the outcome. The only variable significantly influencing the AOFAS (p = .004) and OMAS (p < .001) was body mass index (BMI; rs = -0.522 and -0.606, respectively), with a higher BMI resulting in inferior outcome scores. Complications were observed in 3 patients, 2 with superficial skin necrosis at the posterolateral incision and 1 nonunion of the medial malleolus. Taken together, these data show that intra-articular injuries were common in ankle fractures. Bi- and trimalleolar fractures were particularly at risk for full-thickness lesions. A higher BMI tended to result in inferior outcome scores. Arthroscopically assisted open reduction and internal fixation led to good to excellent results in all but 1 patient.

Development of an accelerated functional rehabilitation protocol following minimal invasive Achilles tendon repair.

PURPOSE: Surgical repair after acute Achilles tendon rupture leads to lower re-rupture rates than non-surgical treatment. After open repair, early functional rehabilitation improves outcome, but there are risks of infection and poor wound healing. Minimal invasive surgery reduces these risks; however, there are concerns about its stability. Consequently, physicians may have reservations about adopting functional rehabilitation. There is still no consensus about the post-operative treatment after minimal invasive repair. The aim of this study was to define the most effective and safe post-operative rehabilitation protocol following minimal invasive repair. METHODS: A systematic literature search in Embase, MEDLINE and Cochrane Library for prospective trials reporting on early functional rehabilitation after minimal invasive repair was performed. Seven studies were included. RESULTS: One randomized controlled trail, one prospective comparative and five prospective non-comparative studies were identified. Four studies performed full weight bearing, all demonstrating good functional results, an early return to work/sports and high satisfaction. One study allowed early mobilization leading to excellent subjective and objective results. The only randomized controlled trial performed the most accelerated protocol demonstrating a superior functional outcome and fewer complications after immediate full weight bearing combined with free ankle mobilization. The non-comparative study reported high satisfaction, good functional results and an early return to work/sports following combined treatment. CONCLUSION: Immediate weight bearing in a functional brace, together with early mobilization, is safe and has superior outcome following minimally invasive repair of Achilles tendon rupture. Our recommended treatment protocol provides quality assurance for the patient and reliability for the attending physician. LEVEL OF EVIDENCE: II.

Significant increase of pathogen detection rate by dry arthroscopic biopsies at suspected low-grade infection following total knee arthroplasty: a prospective observational study.

INTRODUCTION: The differentiation between stiff-knee and low-grade periprosthetic joint infection (PJI) is the current diagnostic challenge in total knee (TKA) revision arthroplasty. The aim of this study was to investigate the additional value of dry biopsies, compared to wet biopsies, in patients presenting with knee stiffness following primary TKA. MATERIALS AND METHODS: Single center, prospective observational study. Consecutive patients with joint stiffness of unknown origin following primary TKA were enrolled. Patient assessment followed the diagnostic standard algorithm. During diagnostic arthroscopy, synovial fluid (synovial WBC, PMN%) and five dry biopsies (dry) were collected. Then fluid was infused and another five microbiology (wet) and five histological biopsies gathered, all from identical locations. The primary outcome parameter was the difference between the pathogens in wet and dry biopsies. RESULTS: 71 patients (61% females, 67 ± 10 years) were eligible. Preoperative blood serology mean CRP (0.7 ± 1.5 mg/dl; p = 0.852), WBC (6.6 ± 1.7 G/l; p = 0.056), and synovial fluid mean WBC (1639 ± 2111; p = 0.602), PMN% (38 ± 28; p = 0.738) did not differ between patients with negative, positive wet or dry biopsies. The histology was in 11% positive (p = 0.058). In 32% at least one pathogen was detected, 48% from wet, 44% from dry biopsies. An inhomogeneous distribution was found. Cutibacterium acnes (100%) was solely found in wet, Micrococcus luteus (75%), Staphylococcus capitis (67%), and Micrococcus lylae (100%) were predominantly found in dry biopsies. Additional dry biopsies increased the pathogen detection rate by 49%. CONCLUSION: The addition of dry biopsies to the current standard diagnostic algorithm for PJI increased the pathogen detection rate by 49%.

Analysis of the three-dimensional anatomical variance of the distal radius using 3D shape models.

BACKGROUND: Various medical fields rely on detailed anatomical knowledge of the distal radius. Current studies are limited to two-dimensional analysis and biased by varying measurement locations. The aims were to 1) generate 3D shape models of the distal radius and investigate variations in the 3D shape, 2) generate and assess morphometrics in standardized cut planes, and 3) test the model's classification accuracy. METHODS: The local radiographic database was screened for CT-scans of intact radii. 1) The data sets were segmented and 3D surface models generated. Statistical 3D shape models were computed (overall, gender and side separate) and the 3D shape variation assessed by evaluating the number of modes. 2) Anatomical landmarks were assigned and used to define three standardized cross-sectional cut planes perpendicular to the main axis. Cut planes were generated for the mean shape models and each individual radius. For each cut plane, the following morphometric parameters were calculated and compared: maximum width and depth, perimeter and area. 3) The overall shape model was utilized to evaluate the predictive value (leave one out cross validation) for gender and side identification within the study population. RESULTS: Eighty-six radii (45 left, 44% female, 40 ± 18 years) were included. 1) Overall, side and gender specific statistical 3D models were successfully generated. The first mode explained 37% of the overall variance. Left radii had a higher shape variance (number of modes: 20 female / 23 male) compared to right radii (number of modes: 6 female / 6 male). 2) Standardized cut planes could be defined using anatomical landmarks. All morphometric parameters decreased from distal to proximal. Male radii were larger than female radii with no significant side difference. 3) The overall shape model had a combined median classification probability for side and gender of 80%. CONCLUSIONS: Statistical 3D shape models of the distal radius can be generated using clinical CT-data sets. These models can be used to assess overall bone variance, define and analyze standardized cut-planes, and identify the gender of an unknown sample. These data highlight the potential of shape models to assess the 3D anatomy and anatomical variance of human bones.

The value of arthroscopy in the treatment of complex ankle fractures - a protocol of a randomised controlled trial.

BACKGROUND: An anatomical reconstruction of the ankle congruity is the important prerequisite in the operative treatment of acute ankle fractures. Despite anatomic restoration patients regularly suffer from residual symptoms after these fractures. There is growing evidence, that a poor outcome is related to the concomitant traumatic intra-articular pathology. By supplementary ankle arthroscopy anatomic reduction can be confirmed and associated intra-articular injuries can be treated. Nevertheless, the vast majority of complex ankle fractures are managed by open reduction and internal fixation (ORIF) only. Up to now, the effectiveness of arthroscopically assisted fracture treatment (AORIF) has not been conclusively determined. Therefore, a prospective randomised study is needed to sufficiently evaluate the effect of AORIF compared to ORIF in complex ankle fractures. METHODS/DESIGN: We perform a randomised controlled trial at Munich University Clinic enrolling patients (18-65 years) with an acute ankle fracture (AO 44 A2, A3, B2, B3, C1 - C3 according to AO classification system). Patients meeting the inclusion criteria are randomised to either intervention group (AORIF, n = 37) or comparison group (ORIF, n = 37). Exclusion criteria are fractures classified as AO type 44 A1 or B1, pilon or plafond-variant injury or open fractures. Primary outcome is the AOFAS Score (American Orthopaedic Foot and Ankle Society). Secondary outcome parameter are JSSF Score (Japanese Society of Surgery of the Foot), Olerud and Molander Score, Karlsson Score, Tegner Activity Scale, SF-12, radiographic analysis, arthroscopic findings of intra-articular lesions, functional assessments, time to return to work/sports and complications. This study protocol is accordant to the SPIRIT 2013 recommendation. Statistical analysis will be performed using SPSS 22.0 (IBM). DISCUSSION: The subjective and functional outcome of complex ankle fractures is regularly unsatisfying. As these injuries are very common it is essential to improve the postoperative results. Potentially, arthroscopically assisted fracture treatment can significantly improve the outcome by addressing the intra-articular pathologies. Given the absolute lack of studies comparing AORIF to ORIF in complex ankle fractures, this randomised controlled trail is urgently needed to evaluate the effectiveness of additional arthroscopy. TRIAL REGISTRATION: ClinicalTrials.gov reference: NCT02449096 (Trial registration date: April 7th, 2015).

Using self-drilling screws in volar plate osteosynthesis for distal radius fractures: a feasibility study.

BACKGROUND: Symptomatic extensor tendon irritation is a frequent complication in volar plate osteosynthesis of distal radius fractures. It is typically caused by dorsal screw protrusion and overdrilling of the dorsal cortex. The use of self-drilling locking screws (SDLS) could overcome both causes. The practical applicability of SDLS depends on two prerequisites: (1) the feasibility of preoperative distal screw length determination, and (2) sufficient primary biomechanical stability of SDLS compared to standard locking screws (SLS). METHODS: We first assessed the feasibility of preoperative screw length determination (1): Distal radius width, depth and distal screw lengths were measured in 38 human radii. Correlations between distal radius width and depth were assessed, a cluster analysis (Ward's method and squared Euclidean distance) for distal radius width conducted, and intra-cluster screw lengths analyzed (ANOVA). The biomechanical performance of SDLS (2) was assessed by comparison to SLS in a distal radius fracture model (AO-23 A3). 75 % distal screw length was chosen for both groups to simulate a worst-case scenario. Uniaxial compression tests were conducted to measure stiffness, elastic limit, maximum force and residual tilt. Statistics comprised of independent sample t-tests and a Bonferroni correction (p < 0.0125). RESULTS: (1) Distal radius width and depth showed a high correlation (R (2) = 0.79; p < 0.001). Three distal radius width clusters could be identified: small <34 mm; medium 34-36.9 mm; large >36.9 mm. ANOVA and Tukey post-hoc analysis revealed significantly different volar-dorsal depths (p < 0.05) for nearly all screws. (2) To assess biomechanical stability nine specimens were tested each; no significant differences were found between the SDLS and SLS groups. CONCLUSIONS: This feasibility study demonstrates that (1) distal radius width can be used as a predictor for distal screw length and (2) that SDLS provides mechanical stability equivalent to SLS. These results highlight the feasibility of applying SDLS screws in volar plate osteosynthesis at least in extraarticular fractures.

Ankle dorsiflexion: what is normal? Development of a decision pathway for diagnosing impaired ankle dorsiflexion and M. gastrocnemius tightness.

INTRODUCTION: Impaired ankle dorsiflexion (ADF) is known to increase forefoot pressure, which is associated to various pathologies affecting the foot and ankle. M. gastrocnemius tightness (MGT) is its most common cause. Up to date we are missing a standardized examination procedure, norm values, and a valid decision pathway to diagnose impaired ADF and MGT. The aim of this study was to define norm values for ADF using a standardized examination procedure. These were used to define a decision pathway to diagnose impaired ADF and MGT. MATERIALS AND METHODS: 64 young, asymptomatic subjects were examined. Based on a standardized examination procedure, bilateral ADF, both with the knee extended and flexed, non-weight bearing and weight bearing, was assessed by three investigators. Inter-rater test reliability and norm values for ADF were calculated. Side differences were analyzed. ADF differences between the knee extended and flexed were calculated. RESULTS: The standardized examination procedure revealed high ICC values (0.876-0.915). ADF values with the knee extended for the left/right limb were 22.7° ± 5.9° [95 % CI 21.2°-24.3°]/23.4° ± 6.5° [95 % CI 21.7°-25.1°] non-weight bearing and 33.3° ± 5.5° [95 % CI 31.9°-34.7°]/33.6° ± 5.6° [95 % CI 32.1°-35.0°] weight bearing. Physiological side differences with the knee extended were <6° (95 % CI). Knee flexion resulted in an approximate ADF increase of 10°. CONCLUSIONS: Based on an extensive systematic approach, physiological values for ADF were assessed in a large asymptomatic population. This allowed the definition of a decision pathway to diagnose impaired ADF and MGT. Patients presenting with pathologies associated with impaired ADF should be examined according to the herein presented examination protocol. This systematic approach provides a consistent definition of impaired ADF and MGT, which is the prerequisite to study the effectiveness of treatment strategies for MGT.

Biomechanical Testing of Distal Radius Fracture Treatments: Boundary Conditions Significantly Affect the Outcome of In Vitro Experiments.

The variety of experimental setups used during in vitro testing of distal radius fracture treatments impairs interstudy comparison and might lead to contradictory results. Setups particularly differ with respect to their boundary conditions, but the influence on the experimental outcome is unknown. The aim of this biomechanical study was to investigate the effects of 2 common boundary conditions on the biomechanical properties of an extra-articular distal radius fracture treated using volar plate osteosynthesis. Uniaxial compression tests were performed on 10 synthetic radii that were randomized into a proximally constrained group (ProxConst) or proximally movable group (ProxMove). The load was applied distally through a ball joint to enable distal fragment rotation. A significantly larger (ProxConst vs ProxMove) stiffness (671.6 ± 118.9 N·mm(-1) vs 259.6 ± 49.4 N·mm(-1)), elastic limit (186.2 ± 24.4 N vs 75.4 ± 20.2 N), and failure load (504.9 ± 142.5 N vs 200.7 ± 49.0 N) were found for the ProxConst group. The residual tilt did not differ significantly between the 2 groups. We concluded that the boundary conditions have a profound impact on the experimental outcome and should be considered more carefully in both study design and interstudy comparison.

Laparoscopic adrenalectomy--10-year experience at a teaching hospital.

BACKGROUND: Minimally invasive adrenalectomy has been adopted as the treatment of choice for benign adrenal tumors. This study aimed to investigate the outcome of laparoscopic adrenalectomies performed over a 10-year period at a teaching hospital. METHODS: All laparoscopic adrenalectomies carried out between 1 April 2000 and 31 March 2010 were evaluated with respect to perioperative management, complications, conversion rate, learning curve, tumor size, and surgically relevant characteristics of different adrenal pathologies. RESULTS: Over a period of 10 years, 215 laparoscopic lateral transabdominal adrenalectomies were carried out for Conn's syndrome (n = 90), Cushing's syndrome (n = 72), pheochromocytoma (n = 30), metastatic disease (n = 8), incidentalomas (n = 10), and other rare adrenal pathologies (n = 5). Morbidity, mortality, and conversion rate were 7.0, 0.9, and 4.2 %, respectively. Patients with Cushing's disease and bilateral adrenalectomy showed a higher complication rate. In retrospect, the indication for a laparoscopic approach was at least questionable in five cases. During these 10 years, four surgeons unfamiliar with the technique received intensive training to a defined plan. CONCLUSIONS: Laparoscopic adrenalectomy represents a safe operating technique associated with few complications and a low conversion rate. Patients with severe Cushing's disease are prone to complications and require intensive monitoring postoperatively. Laparoscopic adrenalectomy is associated with a learning curve, and particular emphasis should be given to surgical training.

The influence of knee position on ankle dorsiflexion - a biometric study.

BACKGROUND: Musculus gastrocnemius tightness (MGT) can be diagnosed by comparing ankle dorsiflexion (ADF) with the knee extended and flexed. Although various measurement techniques exist, the degree of knee flexion needed to eliminate the effect of the gastrocnemius on ADF is still unknown. The aim of this study was to identify the minimal degree of knee flexion required to eliminate the restricting effect of the musculus gastrocnemius on ADF. METHODS: Bilateral ADF of 20 asymptomatic volunteers aged 18-40 years (50% female) was assessed prospectively at six different degrees of knee flexion (0°, 20°, 30°, 45°, 60°, 75°, Lunge). Tests were performed following a standardized protocol, non weightbearing and weightbearing, by two observers. Statistics comprised of descriptive statistics, t-tests, repeated measurement ANOVA and ICC. RESULTS: 20 individuals with a mean age of 27 ± 4 years were tested. No significant side to side differences were observed. The average ADF [95% confidence interval] for non weightbearing was 4° [1°-8°] with the knee extended and 20° [16°-24°] for the knee 75° flexed. Mean weightbearing ADF was 25° [22°-28°] for the knee extended and 39° [36°-42°] for the knee 75° flexed. The mean differences between 20° knee flexion and full extension were 15° [12°-18°] non weightbearing and 13° [11°-16°] weightbearing. Significant differences of ADF were only found between full extension and 20° of knee flexion. Further knee flexion did not increase ADF. CONCLUSION: Knee flexion of 20° fully eliminates the ADF restraining effect of the gastrocnemius. This knowledge is essential to design a standardized clinical examination assessing MGT.

Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm.

PURPOSE: Olecranon bursitis and prepatellar bursitis are common entities, with a minimum annual incidence of 10/100,000, predominantly affecting male patients (80 %) aged 40-60 years. Approximately 1/3 of cases are septic (SB) and 2/3 of cases are non-septic (NSB), with substantial variations in treatment regimens internationally. The aim of the study was the development of a literature review-based treatment algorithm for prepatellar and olecranon bursitis. METHODS: Following a systematic review of Pubmed, the Cochrane Library, textbooks of emergency medicine and surgery, and a manual reference search, 52 relevant papers were identified. RESULTS: The initial differentiation between SB and NSB was based on clinical presentation, bursal aspirate, and blood sampling analysis. Physical findings suggesting SB were fever >37.8 °C, prebursal temperature difference greater 2.2 °C, and skin lesions. Relevant findings for bursal aspirate were purulent aspirate, fluid-to-serum glucose ratio <50 %, white cell count >3,000 cells/µl, polymorphonuclear cells >50 %, positive Gram staining, and positive culture. General treatment measures for SB and NSB consist of bursal aspiration, NSAIDs, and PRICE. For patients with confirmed NSB and high athletic or occupational demands, intrabursal steroid injection may be performed. In the case of SB, antibiotic therapy should be initiated. Surgical treatment, i.e., incision, drainage, or bursectomy, should be restricted to severe, refractory, or chronic/recurrent cases. CONCLUSIONS: The available evidence did not support the central European concept of immediate bursectomy in cases of SB. A conservative treatment regimen should be pursued, following bursal aspirate-based differentiation between SB and NSB.

[Fractures of the talar neck and body : An overview]. / Frakturen des Talushalses und -Corpus : Eine Übersicht.

Fractures to the talar neck and talar body (central talar fractures) are rare injuries but often result in devastating outcomes. It is therefore important to diagnose these injuries early and provide the best possible treatment. The analysis, classification, and surgical planning of central talar fractures should be based on computed tomography (CT) imaging. In the case of dislocated fractures, surgeons must strive for an anatomic reduction and fixation. The approach routes are based on the fracture morphology and must enable adequate reduction of the fracture. This can often only be achieved by two or more approach routes. The outcome correlates with fracture complexity and the quality of the reduction. Complications such as avascular necrosis and posttraumatic osteoarthritis are common and have a negative effect on the results of the treatment.

Value of Intraoperative 3D Imaging on the Quality of Reduction of the Distal Tibiofibular Joint When Using a Suture-Button System.

BACKGROUND: The quality of reduction of the distal tibiofibular joint (DTFJ) has a major impact on the outcome. Novel suture-button systems as well as intraoperative 3D imaging can be applied to increase the quality of DTFJ reduction intraoperatively. The individual effect of either remains unknown. The aim of this study was to investigate the value of intraoperative 3D imaging on the quality of reduction of the DTFJ when using a suture-button system. METHODS: Retrospective, radiographic study including adult patients who underwent surgical stabilization of the syndesmosis with a suture-button system for acute, unilateral, unstable syndesmotic injuries with postoperative bilateral CT imaging. The use of an intraoperative 3D scan was the individual surgeon's choice. Assessed was whether the intraoperative 3D imaging had an influence on the postoperative quality of DTFJ reduction and revision rates. These findings were put in perspective to the correction potential of the suture-button system. RESULTS: A total of 147 patients were included; 76 of these received an intraoperative 3D imaging. Neither the rate of formal malreduction (17% vs 17%) nor the postoperative revision rate (4% vs 3%) differed significantly between patients with or without intraoperative 3D imaging. Intraoperative 3D imaging revealed a false-negative rate of 14%. The intrinsic correction potential of the suture-button system reduced the number of formally malreduced DTFJs in both groups by 51%. CONCLUSION: The additional value of intraoperative 3D imaging to assess the quality of DTFJ reduction in our series did not improve syndesmotic reduction when using a flexible suture-button system. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort study.

Compensation of Dynamic Fixation Systems in the Quality of Reduction of Distal Tibiofibular Joint in Acute Syndesmotic Complex Injuries: A CT-Based Analysis.

BACKGROUND: There is an ongoing discussion on how to best stabilize syndesmotic injuries. Previous studies have indicated a better quality of reduction of the distal tibiofibular joint (DTFJ) for the suture button systems compared to syndesmotic screw fixation. Still, the reason for this superiority remains unclear. The aims of this retrospective study were to (1) analyze the deviation of the tibial and fibular drilling tunnels of the suture button system and (2) to compare these to the quality of reduction of the DTFJ assessed on bilateral postoperative CT images. METHODS: Included were all adult patients who underwent syndesmotic stabilization for an acute injury using a suture button system, with postoperative, bilateral CT imaging over a 10-year period. A total of 147 patients were eligible. Based on individually reconstructed axial CT slices, the postoperative quality of reduction of the DTFJs was rated on bilateral CT images. Furthermore, the rotation and translation of the suture button drilling tunnels were analyzed. Based on these measurements, the intraoperative reduction of the DTFJ was recalculated and again rated. Using these values, the correction potential of suture button systems on the reduction of the DTFJ was analyzed. RESULTS: (1) The drilling tunnel deviated considerably for both rotation |2.3±2.1 degrees| (range: |0.0-13.1 degrees|) and translation |0.9±0.8 mm| (range: |0-4.3 mm|). Based on the deviation of the drilling tunnels in fibula and tibia, the calculated intraoperative reduction of the DTFJ was classified as malreduced in 35.4%. (2) The DTFJ was postoperatively identified as malreduced in 17% of patients. Overall, the suture button system tended to compensate toward a more anatomical reduction both in the axial and sagittal plane. CONCLUSION: A suture button system postoperatively deviates and apparently has the capacity to compensate for intraoperative malreduction. Analysis of the drilling tunnels revealed that the use of a rigid fixation system would have doubled the postoperative malreduction rate.

Comparison of initial compression of the medial, lateral, and posterior screws in an ankle fusion construct.

BACKGROUND: One of the requirements for successful ankle arthrodesis is adequate compression by the fixation across the fusion surfaces. A common screw construct for ankle fusion is three crossed screws from proximal-to-distal. Because the screws are inserted nearly orthogonal to each other, it is possible minimal additional compression is obtainable once the first screw is inserted. The aim of this study was to determine which of the three screws gave the greatest initial compression and theoretically should be inserted first. MATERIALS AND METHODS: Seventeen cadaver limbs were dissected to expose the anterior and posterior aspects of the tibiotalar joint. Three Fuji film templates were created for each ankle joint with a hole to accommodate a 7.0-mm cannulated screw. Each film was tested with a single medial, lateral, or posterior screw. The Fuji films were then analyzed for contact area, percent contact area, and pressure. RESULTS: There was no difference in the total contact area, percent contact area, or pressure generated between the three screws. The mean contact area for all screws was 11% of the joint surface. All three screws had greater contact area and percent contact area over the anterior half of the ankle joint. CONCLUSION: The medial, lateral, and posterior screws were equivalent with respect to contact area, percent contact area, and pressure generated across the tibiotalar joint. All three screws had greater contact area over the anterior half of the joint. Only 11% of the tibiotalar joint surface came in contact following the insertion of a single partially threaded screw. CLINICAL RELEVANCE: In a neutrally aligned ankle arthrodesis the order of screw insertion does not affect the amount of compression ultimately achieved at the fusion site.

Towards optimization of volar plate fixations of distal radius fractures: Using finite element analyses to reduce the number of screws.

BACKGROUND: Using fewer distal screws in volar plate fixation of distal radius fractures could reduce treatment costs and complications. However, there is currently no consensus on the ideal screw configuration, likely due to experimental limitations and its subject-specific nature. In this study, finite element analysis was used to investigate (1) if reducing the number of screws is biomechanically feasible and (2) if an optimal screw configuration is subject-specific. METHODS: Validated subject-specific finite element models of 16 human radii with extra articular distal radius fractures and volar plate fixation with six distal screws were used as a baseline. 41 additional configurations with three to six distal screws were simulated for each subject. Axial stiffness and peri-implant strains around the distal screws were evaluated. Subject-specific optimum configurations were determined using a lower bound for the axial stiffness and minimizing peri-implant strains. FINDINGS: Even using three distal screws led to only minor deterioration of the biomechanical properties in the best configuration (axial stiffness: -11.2%, peri-implant strains: -35.0%), but a considerable deterioration in the worst configuration (axial stiffness: -46.2%, peri-implant strains: +112.4%). The optimization showed that the ideal screw configuration is subject-specific and on average 1.9 screws could be saved based on the herein used optimization criterion. INTERPRETATION: This study highlights that not only how many, but which screws are used in volar plate fixation of distal radius fractures is critical. Using a patient-specific selection of distal screws bears potential to save costs and reduce complications.