Aims. Comparison of the outcome between the supine or prone positioned child with a supracondylar humerus fracture by measuring anaesthetic and operating time, functional outcomes and complications. Methods. All children with isolated Gartland 2 and 3 supracondylar humerus fractures were who were admitted to our institute, were asked to participate in the the study. For surgery, the participating children were either operated on in a ‘supine’ or ‘prone’ position. The children were randomly allocated to either the ‘supine’ or ‘prone’ position. The fractures were preferably treated by closed reduction and percutaneous pinning with k-wires. However, if the fracture proved difficult to reduce, we proceeded to open reduction via medial and lateral approach. All fractures were stabilized with one medial and one lateral k-wire. The children were immobilized in a reinforced above elbow back-slab. Total anaesthetic and surgical time were meticulously recorded. Patients were followed up in our outpatient clinic at one week, four weeks (at which time the k-wires were removed). Three months post operatively, elbow extension, flexion and total range of movement was assessed in all children. Results Twenty children with isolated Gartland 2 and 3 supracondylar humerus fractures were included in this study. Nine children (5 ± 1 years, 7 boys and 2 girls) were operated on in a prone position, while 11 children (6 ± 2 years, 10 boys and 1 girls) were operated on in a supine position. Results. The anaesthetic time was significantly longer in the prone (20 ± 8 min) than in the supine position(10 ± 3 min) (p = 0.001). In line with this, surgical time showed a tendency to also be longer in prone (44 ± 36 min) than supine position (18 ± 18 min) (p = 0.08). No differences between prone and supine operated children was found for elbow extension (4.4 ± 7.7° vs. 3.6 ± 7.1°, respectively (p = 0.81)), elbow flexion (129.4 ± 8.8° vs. 127.0 ±8.8°, respectively (p = 0.67)) and/ or elbow range of motion (125.0 ± 16.0° vs. 124.1 ± 14.6°, respectively (p = 0.90)). Conclusion. As no differences were found in elbow mobility 3 months post-operatively and anesthetic and surgical time tends to be longer in a prone position, this study suggests that operating children with Gartland 2 and 3 supracondylar humerus fractures in a supine position is more favorable. NO DISCLOSURES

Diagnostic interpretation error of paediatric musculoskeletal (MSK) radiographs can lead to late presentation of injuries that subsequently require more invasive surgical interventions with increased risks of morbidity. We aimed to determine the radiograph factors that resulted in diagnostic interpretation challenges for emergency physicians reviewing pediatric MSK radiographs.

Emergency physicians provided diagnostic interpretations on 1,850 pediatric MSK radiographs via their participation in a web-based education platform. From this data, we derived interpretation difficulty scores for each radiograph using item response theory. We classified each radiograph by body region, diagnosis (fracture/dislocation absent or present), and, where applicable, the specific fracture location(s) and morphology(ies). We compared the interpretation difficulty scores by diagnosis, fracture location, and morphology. An expert panel reviewed the 65 most commonly misdiagnosed radiographs without a fracture/dislocation to identify normal imaging findings that were commonly mistaken for fractures.

We included data from 244 emergency physicians, which resulted in 185,653 unique radiograph interpretations, 42,689 (23.0%) of which were diagnostic errors. For humerus, elbow, forearm, wrist, femur, knee, tibia-fibula radiographs, those without a fracture had higher interpretation difficulty scores relative to those with a fracture; the opposite was true for the hand, pelvis, foot, and ankle radiographs (p < 0 .004 for all comparisons). The descriptive review demonstrated that specific normal anatomy, overlapping bones, and external artefact from muscle or skin folds were often mistaken for fractures. There was a significant difference in difficulty score by anatomic locations of the fracture in the elbow, pelvis, and ankle (p < 0 .004 for all comparisons). Ankle and elbow growth plate, fibular avulsion, and humerus condylar were more difficult to diagnose than other fracture patterns (p < 0 .004 for all comparisons).

We identified actionable learning opportunities in paediatric MSK radiograph interpretation for emergency physicians. We will use this information to design targeted education to referring emergency physicians and their trainees with an aim to decrease delayed and missed paediatric MSK injuries.

Diagnostic interpretation error of paediatric musculoskeletal (MSK) radiographs can lead to late presentation of injuries that subsequently require more invasive surgical interventions with increased risks of morbidity. We aimed to determine the radiograph factors that resulted in diagnostic interpretation challenges for emergency physicians reviewing pediatric MSK radiographs.

Emergency physicians provided diagnostic interpretations on 1,850 pediatric MSK radiographs via their participation in a web-based education platform. From this data, we derived interpretation difficulty scores for each radiograph using item response theory. We classified each radiograph by body region, diagnosis (fracture/dislocation absent or present), and, where applicable, the specific fracture location(s) and morphology(ies). We compared the interpretation difficulty scores by diagnosis, fracture location, and morphology. An expert panel reviewed the 65 most commonly misdiagnosed radiographs without a fracture/dislocation to identify normal imaging findings that were commonly mistaken for fractures.

We included data from 244 emergency physicians, which resulted in 185,653 unique radiograph interpretations, 42,689 (23.0%) of which were diagnostic errors. For humerus, elbow, forearm, wrist, femur, knee, tibia-fibula radiographs, those without a fracture had higher interpretation difficulty scores relative to those with a fracture; the opposite was true for the hand, pelvis, foot, and ankle radiographs (p < 0 .004 for all comparisons). The descriptive review demonstrated that specific normal anatomy, overlapping bones, and external artefact from muscle or skin folds were often mistaken for fractures. There was a significant difference in difficulty score by anatomic locations of the fracture in the elbow, pelvis, and ankle (p < 0 .004 for all comparisons). Ankle and elbow growth plate, fibular avulsion, and humerus condylar were more difficult to diagnose than other fracture patterns (p < 0 .004 for all comparisons).

We identified actionable learning opportunities in paediatric MSK radiograph interpretation for emergency physicians. We will use this information to design targeted education to referring emergency physicians and their trainees with an aim to decrease delayed and missed paediatric MSK injuries.

The role of anconeus in elbow stability has been a long-standing debate. Anatomical and electromyographic studies have suggested a potential role as a stabilizer. However, to our knowledge, no clinical or biomechanical studies have investigated its role in improving the stability of a lateral collateral ligament (LCL) deficient elbow. Seven cadaveric upper extremities were mounted in an elbow motion simulator in the varus position. An LCL injured model was created by sectioning of the common extensor origin, and the LCL. The anconeus tendon and its aponeurosis were sutured in a Krackow fashion and tensioned to 10N and 20N through a transosseous tunnel at its origin. Varus-valgus angles and ulnohumeral rotations were recorded using an electromagnetic tracking system during simulated active elbow flexion with the forearm pronated and supinated. During active motion, the injured model resulted in a significant increase in varus angulation (5.3°±2.9°, P=.0001 pronation, 3.5°±3.4°, P=.001 supination) and external rotation (ER) (8.6°±5.8°, P=.001 pronation, 7.1°±6.1°, P=.003 supination) of the ulnohumeral articulation compared to the control state (varus angle −2.8°±3.4° pronation, −3.3°±3.2° supination, ER angle 2.1°±5.6° pronation, 1.6°±5.8° supination). Tensioning of the anconeus significantly decreased the varus angulation (−1.2°±4.5°, P=.006 for 10N in pronation, −3.9°±4°, P=.0001 for 20N in pronation, −4.3°±4°, P=.0001 for 10N in supination, −5.3°±4.2°, P=.0001 for 20N in supination) and ER angle (2.6°±4.5°, P=.008 for 10N in pronation, 0.3°±5°, P=.0001 for 20N in pronation, 0.1°±5.3°, P=.0001 for 10N in supination, −0.8°±5.3°, P=.0001 for 20N in supination) of the injured elbow. Comparing anconeus tensioning to the control state, there was no significant difference in varus-valgus angulation except with anconeus tensioning to 20N with the forearm in supination which resulted in less varus angulation (P=1 for 10N in pronation, P=.267 for 20N in pronation, P=.604 for 10N in supination, P=.030 for 20N in supination). Although there were statistically significant differences in ulnohumeral rotation between anconeus tensioning and the control state (except with anconeus tensioning to 10N with the forearm in pronation which was not significantly different), anconeus tensioning resulted in decreased external rotation angle compared to the control state (P=1 for 10N in pronation, P=.020 for 20N in pronation, P=.033 for 10N in supination, P=.001 for 20N in supination). In the highly unstable varus elbow orientation, anconeus tensioning restores the in vitro stability of an LCL deficient elbow during simulated active motion with the forearm in both pronation and supination. Interestingly, there was a significant difference in varus-valgus angulation between 20N anconeus tensioning with the forearm supinated and the control state, with less varus angulation for the anconeus tensioning which suggests that loads less than 20N is sufficient to restore varus stability during active motion with the forearm supinated. Similarly, the significant difference observed in ulnohumeral rotation between anconeus tensioning and the control state suggests that lesser degrees of anconeus tensioning would be sufficient to restore the posterolateral instability of an LCL deficient elbow. These results may have several clinical implications such as a potential role for anconeus strengthening in managing symptomatic lateral elbow instability

The clinical diagnosis of distal radioulnar joint (DRUJ) instability remains challenging. The current diagnostic gold standard is a dynamic computerized topography (CT) scan. This investigation compares the affected and normal wrists in multiple static positions of forearm rotation.. However, its accuracy has been questioned, as the wrist is unloaded and not placed under stress. This may fail to capture DRUJ instability that does not result in static malalignment between the ulnar head and sigmoid notch. The purpose of this biomechanical study was to evaluate the effectiveness of both dynamic and stress CT scans in detecting DRUJ instability. A customized DRUJ arthrometer was designed that allows for both static positioning, as well as dorsal and volar loading at the DRUJ in various degrees of forearm rotation. Ten fresh frozen cadavers were prepared and mounted in the apparatus. CT scans were performed both in the unloaded condition (dynamic CT) and with each arm subjected to a standardized 50N volar and dorsal force (stress CT) in neutral and maximum pronation/ supination. The TFCC (triangular fibrocartilage complex)was then sectioned peripherally to simulate DRUJ instability and the methodology was repeated. CT scans were then evaluated for displacement using the radioulnar ratio method. When calculating the radioulnar ratio for intact wrists using the dynamic CT technique, values were 0.50, 0.64, 0.34 for neutral, pronation and supination, respectively. When the TFCC was sectioned and protocol repeated, the values for the simulated unstable wrist for dynamic CT were 0.54, 0.62, 0.34 for neutral, pronation and supination, respectively. There was no statistically significant difference between the intact and sectioned states for any position of forearm rotation using dynamic CT. Usingstress CT, mean radioulnar ratios for the intact specimens were calculated to be 0.44, 0.36 and 0.31 for neutral, pronation and supination, respectively. After sectioning the TFCC, the radioulnar ratios increased to 0.61, 0.39 and 0.46 for neutral, pronation and supination. There was a statistically significant difference between intact and simulated-unstable wrists in supination (p = 0.002) and in neutral (p=0.003). The radioulnar ratio values used to measure DRUJ translation for dynamic CT scans were unable to detect a statistically significant difference between stable and simulated unstable wrists. This was true for all positions of forearm rotation. However, when a standard load was placed across the DRUJ, statically significant changes in the radioulnar ratio were seen in neutral and supination between stable and simulated unstable wrists. This discrepancy challenges the current gold standard of dynamic CT in its ability to accurately diagnosis DRUJ instability. It also introduces stress CT as a possible solution for diagnosing DRUJ instability from peripheral TFCC lesions

Pathologies such as Scapho-Lunate Advanced Collapse (SLAC), Scaphoid Non-union Advanced Collapse (SNAC) and Kienbock's disease can lead to arthritis in the wrist. Depending on the articular surfaces that are involved, motion preserving surgical procedures can be performed. Proximal Row Carpectomy (PRC) and Four Corner Fusion (4CF) are tried and tested surgical options. However, prospective studies comparing the two methods looking at sufficient sample sizes are limited in the literature. The purpose of this study was to prospectively compare the early results of PRC vs 4CF performed in a single centre. Patients with wrist arthritis were prospectively enrolled (2015 to 2021) in a single centre in Vancouver, Canada. Thirty-six patients and a total of 39 wrists underwent either a PRC (n=18) or 4CF (n=21) according to pre-operative clinical, radiographical, and intra-operative assessment. Patient-Rated Wrist Evaluation (PRWE) scores were obtained preoperatively, as well as at six months and one year post operatively. Secondary outcomes were range of motion (ROM) of the wrist, grip strength, reoperation and complication rates. Statistical significance was set at p=0.05. Respectively for PRC and 4CF, the average PRWE scores at baseline were 61.64 (SD=19.62) and 63.67 (SD=20.85). There was significant improvement at the six-month mark to 38.81 (SD=22.95) (p=0.031) and 41.33 (SD=26.61) (p=0.007), then further improvement at the 12month mark to 33.11 (SD=23.42) (p=0.007) and 36.29 (SD=27.25) (p=0.002). There was no statistical difference between the two groups at any time point. Regarding ROM, statistical difference was seen in pronation for the PRC group at the 6month mark from an average of 72.18 deg to 61.56 deg and in flexion at the 12 month mark from 47.89 deg to 33.50 deg. All other parameters did not show statistically significant difference post operatively. For ROM of the 4CF group, only flexion at the 12month mark showed statistically significant change from an average of 48.81 deg to 38.03 deg. There was no statistical difference in pre-operative ROM between the two groups. One patient in the 4CF group required a revision for delayed union, and three patients ended up with ulnar sided wrist pain. Patients undergoing PRC and 4CF showed significant improvement in post operative PRWE scores, this reflects existing literature. For 4CF care must be taken to minimise ulnar sided wrist pain by relatively shortening the unar sided carpal column mass. ROM analysis showed that patients lost some wrist flexion ROM post-operatively at the 12month mark with both PRC and 4CF. However, other ROM parameters were unchanged

Introduction. Temporary spanning fixation aims to provide bony stability whilst allowing access and resuscitation of traumatised soft-tissues. Conventional monolateral fixators are prone to half-pin morbidity in feet, variation in construct stability and limited weight-bearing potential. This study compares traditional delta-frame fixators to a circular trauma frame; a virtual tibial ring block spanned onto a fine-wire foot ring fixation. Materials and Methods. The two cohorts were compared for demographics and fracture patterns. The quality of initial reduction and the maintenance of reduction until definitive surgery was assessed by two authors and categorised into four domains. Secondary measures included fixator costs, time to definitive surgery and complications. Results. Fifty-six delta-frames and 48 circular fixators were statistically matched for demographics and fracture pattern. Good or excellent initial reduction was achieved in 51 (91%) delta-frames and 48 (100%) circular fixators (p=0.022). Loss of reduction was observed in 15 (27%) delta-frames and 3 (6%) circular fixators (p<0.001). Post-fixator dislocation occurred in five (9%) delta-frames and one (2%) circular fixator (p=0.147). Duration in spanned fixation was equivalent (11.5 and 11.6 days respectively, p=0.211). Three (5%) delta-frames and 12 (25%) circular fixators were used as definitive fixation. The mean hardware cost was £3,116 for delta-frames and £2,712 for circular fixators. Conclusions. Temporary circular fixation offers statistically superior intra-operative reduction and maintenance of reduction, facilitates weight-bearing and provides more opportunity as the definitive fixation. Circular fixation hardware proved to be less expensive and protected against further scheduled and unscheduled operations

Introduction. Acquired chronic radial head (RH) dislocations present a significant surgical challenge. Co-existing deformity, length discrepancy and RH dysplasia, in multiply operated patients often preclude acute correction. This study reports the clinical and radiological outcomes in children, treated with circular frames for gradual RH reduction. Materials and Methods. Patient cohort from a prospective database was reviewed to identity all circular frames for RH dislocations between 2000–2021. Patient demographics, clinical range and radiographic parameters were recorded. Results. From a cohort of 127 UL frames, 30 chronic RH dislocations (14 anterior, 16 posterior) were identified. Mean age at surgery was 10yrs (5–17). Six pathologies were reported (14 post-traumatic, 11 HME, 2 Nail-Patella, 1 Olliers, OI, Rickets). 70% had a congruent RH reduction at final follow-up. Three cases re-dislocated and 6 had some mild persistent incongruency. Average follow up duration was 4.1yrs (9mnths-11.5yrs). Mean radiographic correction achieved in coronal plane 9. o. , sagittal plane 7. o. and carrying angle 12. o. Mean ulna length gained was 7mm and final ulnar variance was 7mm negative (congenital). All cases achieved bony union with 2 requiring bone grafting. Mean frame duration was 166 days. Mean final range of motion was 64. o. supination, 54 . o. pronation, 2. o. to 138. o. flexion. 5 complications and 7 further operations were reported. Conclusions. The majority of children having frame correction achieve complete correction or minor subluxation, which is well tolerated clinically. Frame assisted reduction is an effective tool for selective complex cases irrespective of the pathology driving the RH dislocation

Previous biomechanical studies of lateral collateral ligament (LCL) injuries and their surgical repair, reconstruction and rehabilitation have primarily relied on gravity effects with the arm in the varus position. The application of torsional moments to the forearm manually in the laboratory is not reproducible, hence studies to date likely do not represent forces encountered clinically. The aim of this investigation was to develop a new biomechanical testing model to quantify posterolateral stability of the elbow using an in vitro elbow motion simulator. Six cadaveric upper extremities were mounted in an elbow motion simulator in the varus position. A threaded screw was then inserted on the dorsal aspect of the proximal ulna and a weight hanger was used to suspend 400g, 600g, and 800g of weight from the screw head to allow torsional moments to be applied to the ulna. An LCL injured (LCLI) model was created by sectioning of the common extensor origin, and the LCL. Ulnohumeral rotation was recorded using an electromagnetic tracking system during simulated active and passive elbow flexion with the forearm pronated and supinated. A repeated measures analysis of variance was performed to compare elbow states (intact, LCLI, and LCLI with 400g, 600g, and 800g of weight). During active motion, there was a significant difference between different elbow states (P=.001 pronation, P=.0001 supination). Post hoc analysis showed that the addition of weights did not significantly increase the external rotation (ER) of the ulnohumeral articulation (10°±7°, P=.268 400g, 10.5°±7.1°, P=.156 600g, 11°±7.2°, P=.111 800g) compared to the LCLI state (8.4°±6.4°) with the forearm pronated. However, with the forearm supinated, the addition of 800g of weight significantly increased the ER (9.2°±5.9°, P=.038) compared to the LCLI state (5.9°±5.5°) and the addition of 400g and 600g of weights approached significance (8.2°±5.7°, P=.083 400g, 8.7°±5.9°, P=.054 600g). During passive motion, there was a significant difference between different elbow states (P=.0001 pronation, P=.0001 supination). Post hoc analysis showed that the addition of 600g and 800g but not 400g resulted in a significant increase in ER of the ulnohumeral articulation (9.3°±7.8°, P=.103 400g, 11.2°±6.2°, P=.004 600g, 12.7°±6.8°, P=.006 800g) compared to the LCLI state (3.7°±5.4°) with the forearm pronated. With the forearm supinated, the addition of 400g, 600g, and 800g significantly increased the ER (11.7°±6.7°, P=.031 400g, 13.5°±6.8°, P=.019 600g, 14.9°±6.9°, P=.024 800g) compared to the LCLI state (4.3°±6.6°). This investigation confirms a novel biomechanical testing model for studying PLRI. Moreover, it demonstrates that the application of even small amounts of torsional moment on the forearm with the arm in the varus position exacerbates the rotational instability seen with the LCL deficient elbow. The effect of torsional loading was significantly worse with the forearm supinated and during passive elbow motion. This new model allows for a more provocative testing of elbow stability after LCL repair or reconstruction. Furthermore, this model will allow for smaller sample sizes to be used while still demonstrating clinically significant differences. Future biomechanical studies evaluating LCL injuries and their repair and rehabilitation should consider using this testing protocol

Introduction. The effect of the implant posterior condylar offset has recently generated much enthusiasm among researchers. Some reports were concerned about the relationship between the posterior condylar offset and an extension gap. However, the posterior condylar offset was measured in a flexed knee position or in reference to femoral anatomy alone. Posterior femoral condylar offset relative to the posterior wall of the tibia (posterior offset ratio; POR) is possibly the risk of knee flexion contracture associated with posterior femoral condylar offset after TKA. However, there are no reports concerning the relationship between POR and flexion contracture in vivo. The aim of this study is to evaluate the relationship between the measurement of POR and flexion contracture of the knee in vivo. Methods. Twenty-seven patients who underwent a primary total knee arthroplasty (PFC Sigma RP-F) were participated in the study. The lateral femoro-tibial angle (lateral FTA) was measured using lateral radiographs obtained by two procedures. Two procedures are applied to obtain true lateral radiographs of the lower extremities. (1) Full-length true lateral radiographs on standing, (2) True lateral radiographs in the prone position (Fig. 1A). ‘Posterior offset ratio’ was defined as Fig. 1B. Significant differences among groups were assessed using two-tailed Student's t-tests. Spearman's correlation analysis was performed to evaluate the relationship between lateral FTA and posterior offset ratio of patients. Results. The mean value of the POR on standing was 14.94 ± 7.53%. The mean value of flexion contracture of the knee on standing was 11.67 ± 9.21 degree and that in the prone position was 4.22 ± 6.17 degree (P = 0.001). The POR was negatively correlated with flexion contracture of the knee in all procedures with statistical significance (standing: r = 0.62, P = 0.0039; prone: r = 0.66, P = 0.0001) (Fig. 2). Discussion. We have evaluated flexion contracture by two procedures. The mean value of flexion contracture of the knee on standing was 11.67 ± 9.21 degree, whereas that in the prone position was 4.22 ± 6.17 degree. We surmised that this discrepancy occurred due to the flexor muscle tension on standing. In terms of the evaluation of posterior soft tissue tightness of the knee, muscle relaxation can be achieved in prone position is rather than standing position. Our study investigated the relationship between the posterior protrusions of the posterior condyle of the femur relative to the tibia (POR) and flexion contracture after TKA evaluated by two measurement procedures. POR is strongly correlated with flexion contracture evaluated by both measurement procedures. The value of POR of this implant in vitro was about 25% in previous study, whereas the mean value of POR in vivo was 14.94%, suggesting that POR in the flexion contracture knee relatively reduced because posterior soft tissue pushed femoral component anteriorly. Our result clearly showed that if posterior clearance is insufficient, flexion contracture occur due to posterior soft tissue tightness. In conclusion, POR after TKA in vivo negatively correlate with flexion contracture presumably because posterior soft tissue pushed femoral component anteriorly

Introduction. Impingement of total hip arthroplasties (THAs) has been reported to cause rim damage of polyethylene liners, and in some instances has led to dislocation and/or mechanical failure of liner locking mechanisms in modular designs. Elevated rim liners are used to improve stability and reduce the risk of dislocation, however they restrict the possible range of motion of the joint, and retrieval studies have found impingement related damage on lipped liners. The aim of this study was to develop a tool for assessing the occurrence of impingement under different activities, and use it to evaluate the effects a lipped liner and position of the lip has on the impingement-free range of motion. MATERIALS & METHOD. A geometrical model incorporated a hemi-pelvis and femur geometries of one individual with a THA (DePuy Pinnacle® acetabular cup with neutral and lipped liners; size 12 Corail® stem with 32mm diameter head) was created in SOLIDWORKS (Dassault Systèmes). Joint motions were taken from kinematic data of activities of daily living that were associated with dislocation of THA, such as stooping to pick an object off the floor and rolling over. The femoral component was positioned to conform within the geometry of the femur, and the acetabular component was orientated in a clinically acceptable position (45° inclination and 20° anteversion). Variation in orientation of the apex of the lip was investigated by rotating about the acetabular axes from the superior (0°) in increments of 45° (0°−315°), and compared to a neutral liner. Results. When a lipped liner was used, implant (neck on acetabular rim) impingement was found to occur when performing sit-to-stand from a normal seat, leg cross and pivot, whereas no impingement occurred with a neutral liner. The presence and position of the lip reduced the impingement-free range of motion, compared to the neutral liner. Impingement occurred when the lip was positioned superiorly and anteriorly, when performing most of the activities that were prone to posterior dislocation, and posteriorly, posterior-superiorly and posterior-inferiorly when performing activities prone to anterior dislocation. During sit-to-stand from a normal seat no impingement occurred when a lipped or neutral liner was used. Bone impingement was observed when the performing the roll activity with both lipped and neutral liners. DISCUSSION. Impingement was observed more with lipped liners compared to neutral liners, this agrees with the findings of some clinical studies. The results indicate that the positioning of the lip influences the possible range of impingement-free motion. Considering this and the improved joint stability of using a lipped liner, a balance is required to achieve an optimal range of motion without increasing the risk of dislocation. This tool could potentially to be used to optimise lipped liner design and position, and could assist with the liner selection for patients based on their activities

The Interosseous Membrane (IOM) of the forearm is made up of ligaments, which are involved in load balancing of the radioulnar joint and the shaft. Motion models of the forearm are necessary for planning orthopedic surgeries, such as osteotomies, which aim at solving limit of the range of motion or instabilities. However, existing models focus on a pure kinematic approach, omitting the physical properties of the ligaments, thus limiting the range of application by missing dynamical effects. We developed a model that takes into account the mechanical properties of the IOM. We simulated the pro-supination by creating an elastic coupling to the desired motion around the standard axis of rotation. We tested our model on a healthy subject, using CT-reconstructed bone models, and literature data for the ligaments. Multiple parameters, including forces of ligaments and positions of landmarks, are output for analysis. The length of the ligaments over pro-supination was in agreement with the literature. Their rest lengths must be recorded in future anatomical studies. The IOM helps in maintaining the contact with cartilage, except in late pronation. Scarring of the central band increases the force generated along the axis of rotation toward the wrist, while scarring of the proximal part does the opposite in pronation. In contrast to kinematic models, the proposed model is helpful to study the effect of physical properties of the IOM, such scarring, on the forearm motion. Future work will be to apply our model to pathological cases, and to compare to clinical observations

Ulnocarpal impaction (UCI) is a common cause of ulnar-sided wrist pain. UCI typically occurs in wrists with positive ulnar variance, which causes altered loading mechanics between the ulnar head, lunate and triquetrum. However, many individuals with positive ulnar variance never develop UCI, and some with neutral or negative ulnar variance do experience UCI. This suggests that other variables contribute to the development of UCI. Suspected culprits include lunate morphology, and dynamic changes with loaded (grip) pronation. If these anatomic variations are contributing to UCI, we expect them to influence functional impairment scores. Therefore, the objective of this study was to evaluate the relationship between radiographic parameters and pre-surgical upper extremity patient-rated outcomes scores (PROS) in patients with a diagnosis of UCI. Retrospective cohort study of patients undergoing ulnar shortening osteotomy or arthroscopic wafer procedure for UCI. Data derived from prospectively collected departmental database that captured demographic, clinical, functional and radiographic information. Radiographic parameters evaluated were: lunate morphology [presence vs. absence of hamate facet; Antuna-Zapico (A-Z) classification], and dynamic changes on grip view [difference in lunate-ulnar head distance (LUD); difference in lunate uncovering index (LUI)]. PROS assessed were QuickDASH and Patient-Rated Wrist Evaluation (PRWE) scores, collected at patient enrolment. ANOVA was used to assess for differences in PROS between A-Z classification groups. Student's t-test was used to assess for differences in PROS based on presence/absence of a hamate facet. Regression analysis evaluated a relationship between change in LUD with grip and PROS, and change in LUI with grip and PROS. Preliminary analysis included 23 wrists, with a mean patient age of 48.9 years [standard deviation (SD) 14.5 years]. Forty-eight percent were male, and the dominant limb was involved in 52.2% of cases. Average QuickDASH and PRWE scores at enrolment were 50.9 (SD 22.2) and 62.2 (SD 22.0), respectively. Assessment of radiographs revealed 17 patients (73.9%) without a hamate facet. Five patients (21.7%) had A-Z Type I lunate morphology, and nine (39.1%) had Type II and Type III morphology, respectively. ANOVA revealed no differences in enrolment QuickDASH (p = 0.185) or PRWE (p = 0.256) scores between A-Z classification groups. Similarly, Student's t-test found no difference based on presence/absence of a hamate facet (QuickDASH p = 0.594; PRWE p = 0.573). Regression analysis revealed no relationship between change in LUD with grip and PROS (QuickDash R2 = 0.020, p = 0.619; PRWE R2 = 0.009, p = 0.733), and no relationship between change in LUI with grip and PROS (QuickDash R2 = 0.000, p = 0.913; PRWE R2 = 0.010, p = 0.722). Preliminary results suggest no relationship between A-Z classification lunate morphology, presence/absence of a hamate facet, change in LUD, or change in LUI and pre-surgical PROS. It is unclear if our findings represent the true relationship between these radiographic parameters and PROS, or reflect our preliminary sample size. Data analysis is ongoing to add clarity to this question

Background. Previously, the Coonrad-Morrey elbow system has typically been performed using linked-type total elbow arthroplasty (TEA) implants. However, this implant have been reported to be associated with some problems, such as wearing down, loosening, the complexity of the necessary surgical techniques and inappropriate implant size for Asian people. The Discovery elbow system (Biomet Inc., Warsaw, US) has recently been developed and it has many advantages when compared to Coonrad-Morrey implant, but the treatment outcome for this system is unclear in patients with rheumatoid arthritis (RA). Objectives. The aim of this study was to clarify the outcome of TEA using the Discovery elbow system. Methods. Eleven RA patients (13 elbows) who underwent TEA using the Discovery elbow system were investigated in this study. Two patients (3 elbows) were males, and 9 patients (10 elbows) were females. Ten were right elbows, and 3 were left elbows. Two elbows has Larsen grade “disease, 7 had grade” disease and 4 elbows underwent revision surgery. The surgical approach used for all cases was Campbell's posterior approach. The Discovery elbow system was installed using cemented fixation. Two weeks after the operation, ROM exercise was started. The elbow ROM, Mayo elbow performance score (MEPS), and any complications observed at baseline, 6 months and 24 months after surgery were assessed. Results. The preoperative elbow ROM (mean±SD) was −33.4±4.4° in extension, 133.5±3.4° in flexion, 48.5±8.4° pronation and 67.7±5.7° in supination. The postoperative elbow ROM (mean±SD) was −18.5±6.2° in extension, 112.7±6.1° in flexion, 70.0±3.4° in pronation and 73.7±1.6° in supination. As a result, a significant improvement was observed in extension, flexion and pronation. The MEPS improved significantly at 6 months and 24 months after surgery. In addition, no implant loosening was found or revision surgery was required at 24 months after surgery. Conclusions. In this study, the elbow function was observed to significantly improve by TEA using the Discovery elbow system based on the short-time outcome. However, further study is still needed to clarify the long-term outcome of this implant in RA patients

Four-Corner Fusions (4CF) and Proximal Row Carpectomies (PRC) are common procedures utilized to treat carpal pathologies and radial sided wrist pain. Usually, the range of motion (ROM) and grip strength (GS) is affected by such conditions. Literature quotes significant reduction in ROM (50–60%) and grip strength (GS) (80% of normal) with PRC and 4CF. This study aims to determine the correlation between pre-operative ROM and GS and post-operative ROM and GS for patients with wrist pain undergoing PRC or 4CF. We hypothesize that ROM between pre-operative and post-operative patients does not change, but GS improves. Data from a prospective database of patients with wrist pain was searched to identify patients who have undergone PRC or 4CF with one year follow-up completed in the past two years. 17 such participants were identified. The diagnosis, pre-operative ROM in flexion, extension, radial deviation, ulnar deviation, pronation and supination, as well as GS at time of surgery and at six months and one year follow up were identified and assessed. The data was analysed to determine correlation between pre-and postoperative ROM and GS. The analysis was subdivided to compare patients treated with PRC versus patients with 4CF. No significant difference between pre- and post-operative ROM was detected, except in flexion at 6 months post-operatively. The average flexion was significantly lower at 6 months (p=0.0251) compared to pre-operative levels. Average flexion pre-operatively and at 6 and 12 months was found to be 46.6 (SD=15), 34.3 (SD=13.3), 51.2 (SD=21.5) respectively. Extension was at 41.4 (SD=15.3) pre-operatively and at 33.4 (SD=12.8) and 42.1 (SD=15.5) at 6 and 12 months post-operatively. Similarly, radial and ulnar deviation averages pre-operatively and at 6 and 12 months post-operatively were found to be 11.33 (SD=5.9), 11.9 (SD=4.5), 16 (SD=8.2) [radial deviation] and 24.1 (SD=8.3), 21.4 (SD=7.3), 26 (SD=12.8) [ulnar deviation]. No significant difference was found in GS at 6 months post-operative. However, significant difference at 12 months post-operatively was observed with an average GS of 28.4 kg (SD=12.8) [p=0.0385]. Average GS pre-operatively and at 6 months was 15.8 kg (SD=9.7) and 17.3 kg (SD=8.9) respectively. This study provides an insight on ROM and GS after PRC and 4CF. It shows that patients do not gain or lose ROM after surgery. As expected, GS improves with treatment as the pain diminishes. It is interesting to note that flexion gets worse at 6 months post-operatively before it bounces back to pre-operative levels

Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow centre of rotation is thought to restore normal muscle moment arms and has been suggested to improve elbow strength and function. While much of the focus has been on humeral component positioning, little is known about the effect of positioning of the ulnar stem on post-operative range of motion and clinical outcomes. The purpose of this study is to determine the effect of the sagittal alignment and positioning of the humeral and ulnar components on the functional outcomes after TEA. Between 2003 and 2016, 173 semi-constrained TEAs (Wright-Tornier Latitude/Latitude EV, Memphis, TN, USA) were performed at our institution, and our preliminary analysis includes 46 elbows in 41 patients (39 female, 7 male). Patients were excluded if they had severe elbow deformity precluding reliable measurement, experienced a major complication related to an ipsilateral upper limb procedure, or underwent revision TEA. For each elbow, saggital alignment was compared pre- and post-operatively. A best fit circle of the trochlea and capitellum was drawn, with its centre representing the rotation axis. Ninety degree tangent lines from the intramedullary axes of the ulna and humerus, and from the olecranon tip to the centre of rotation were drawn and measured relative to the rotation axis, representing the ulna posterior offset, humerus offset, and ulna proximal offset, respectively. In addition, we measured the ulna stem angle (angle subtended by the implant and the intramedullary axis of the ulna), as well as radial neck offset (the length of a 90o tangent line from the intramedullary axis of the radial neck and the centre of rotation) in patients with retained or replaced radial heads. Our primary outcome measure was the quickDASH score recorded at the latest follow-up for each patient. Our secondary outcome measures were postoperative flexion, extension, pronation and supination measured at the same timepoints. Each variable was tested for linear correlation with the primary and secondary outcome measures using the Pearson two-tailed test. At an average follow-up of 6.8 years (range 2–14 years), there was a strong positive correlation between anterior radial neck offset and the quickDASH (r=0.60, p=0.001). There was also a weak negative correlation between the posterior offset of the ulnar component and the qDASH (r=0.39, p=0.031), and a moderate positive correlation between the change in humeral offset and elbow supination (r=0.41, p=0.044). The ulna proximal offset and ulna stem angle were not correlated with either the primary, or secondary outcome measures. When performing primary TEA with radial head retention, or replacement, care should be taken to ensure that the ulnar component is correctly positioned such that intramedullary axis of the radial neck lines up with the centre of elbow rotation, as this strongly correlates with better function and less pain after surgery

Many pre-clinical models of atrophic non-union do not reflect the clinical scenario, some create a critical size defect, or involve cauterization of the tissue which is uncommonly seen in patients. Atrophic non-union is usually developed following high energy trauma leading to periosteal stripping. The most recent reliable model with these aspects involves creating a non-critical gap of 1mm with periosteal and endosteal stripping. However, this method uses an external fixator for fracture fixation, whereas intramedullary nailing is the standard fixation device for long bone fractures. OBJECTIVES. To establish a clinically relevant model of atrophic non-union using intramedullary nail and (1) ex vivo and in vivo validation and characterization of this model, (2) establishing a standardized method for leg positioning for a reliable x-ray imaging. Ex vivo evaluation: 40 rat's cadavers (adult male 5–6 months old), were divided into five groups (n=8 in each): the first group was fixed with 20G intramedullary nail, the second group with 18G nail, the third group with 4-hole plate, the fourth group with 6-hole plate, and the fifth group with an external fixator. Tibiae were harvested by leg disarticulation from the knee and ankle joints. Each group was then subdivided into two subgroups for mechanical testing: one for axial loading (n=4) and one for 4-point bending (n=4) using Zwick/Roell® machine. Statistical analysis was carried out by ANOVA with a fisher post-hoc comparison between groups. A p-value less than 0.05 was considered statistically significant. To maintain the non-critical gap, a spacer was inserted in the gap, the design was refined to minimize the effect on the healing surface area. In vivo evaluation was done to validate and characterize the model. Here, a 1 mm gap was created with periosteal and endosteal stripping to induce non-union. The fracture was then fixed by a hypodermic needle. A proper x-ray technique must show fibula in both views. Therefore, a leg holder was used to hold the knee and ankle joints in 90º flexion and the foot was placed in a perpendicular direction with the x-ray film. Lateral view was taken with the foot parallel to the x-ray film. Ex vivo: axial load stiffness data revealed that intramedullary nails are significantly stronger and stiffer than other devices. Bending load to failure showed that 18G nails are significantly stronger than 20G, thus it is used for the in vivo experiments. In vivo: final iteration revealed 3/3 non-union, and in controls with the periosteum and endosteum intact but with the 1mm non-critical gap, it progressed to 3/3 union. X-ray positioning: A-P view in supine position, there was an unavoidable degree of external rotation in the lower limb, thus the lower part of the fibula appeared behind the tibia. To overcome this, a P-A view of the leg was performed with the body in prone rather, this arrangement allowed both upper and lower parts of the fibula to appear clearly in both views. We report a novel model of atrophic non-union, the surgical procedure is relatively simple and the model is reproducible

In the polytrauma patient, intraoperative patient positioning is one factor thought to influence pulmonary complications associated with intramedullary (IM) nailing of the femur. With regards to lateral femoral nailing, it is currently unknown as to whether the position of the injured lung contributes to changes in pulmonary function. It has been proposed that, similar to prone positioning in the ICU for acute respiratory distress syndrome management, having the injured lung in a dependent position during lateral femoral nailing would prevent barotrauma from hyperinflation and promote gas exchange in the non-dependent healthy lung. This study aims to assess the association between the position of the injured lung during lateral femoral nailing and pulmonary complications as determined by ICU LOS. This retrospective cohort study was conducted at a single level 1 trauma centre. All patients treated with IM nailing for femur fracture between 2006 and 2014 were screened for inclusion. Only patients who 1) underwent lateral femoral nailing and 2) had a significant chest injury, defined by chest Abbreviated Injury Scale (AIS) of three or greater, were included. Patients with bilateral femur fractures or symmetric bilateral thoracic injuries were excluded. Intraoperative position of the lung injury was described depending on whether the injured lung was down, or in the dependent position, during lateral femoral nailing, versus the healthy lung down. The primary outcome was ICU LOS in all study patients. Secondary analysis was performed on the subgroup of patients who were admitted to ICU prior to femoral nailing. Data analysis assessing for differences in ICU LOS between groups was performed through Wilcoxan testing. One hundred and thirteen femur fractures were included in the study. During lateral femoral nailing, 53 patients had the injured lung down and 60 patients had the healthy lung down. No differences between age, ICU admission rate, injury severity score, chest AIS or head AIS were detected between the groups. There were no detectable differences in the rate of ICU admission between patients with the injured lung down (47.2%) and patients with the healthy lung down (46.7%) (P=0.96). We were unable to detect a difference in average ICU LOS between patients who had the injured lung down (4.9 days, 95% CI 2.8 – 7) compared to patients with the healthy lung down (6 days, 95% CI 3.7 – 8.4) during lateral femoral nailing (P=0.73). When looking only at patients who were admitted to ICU prior to femoral nailing, the LOS was 10.3 days (95% CI 7 – 13.7) in injured lung down patients compared to 12.9 days (9.2 – 16.6) in healthy lung down patients (P= 0.25). In patients with chest AIS greater than three, the position of the injured lung during lateral femoral IM nailing does not appear to affect ICU LOS

Management of recurrent instability of the hip requires careful assessment to determine any identifiable causative factors. While plain radiographs can give a general impression, CT is the best methodology for objective measurement. Variables that can be measured include: prosthetic femoral anteversion, comparison to contralateral native femoral anteversion, total offset from the medial wall of the pelvis to the lateral side of the greater trochanter, comparison to total offset on the contralateral side, acetabular inclination, & acetabular anteversion. Wera et al describe potential causes of instability. These are typed into I. Acetabular Component Malposition; II. Femoral Component Malposition; III. Abductor Deficiency; IV. Impingement; V. Late Wear; and VI. Unknown. Acetabular component malposition is the most common cause of instability and so measurement of cup orientation is essential. It is well known that excessive or inadequate anteversion can lead to anterior and posterior dislocation respectively but horizontal components are also associated with posterior dislocation due to deficient posterior/inferior acetabular surface. Similarly, excessive or inadequate femoral anteversion can be easily identified on CT as can insufficient total offset of the reconstructed joint compared to the contralateral side. This can be caused by medialization of the acetabular component. Abductor deficiency can be a soft-tissue cause of instability, but it certainly isn't the only one. Knowledge of the prior surgical exposure can be instructive. Anterior exposures can be prone to deficient anterior capsule just as posterior exposures can be prone to deficient posterior capsule and short rotators, while anterolateral and lateral exposures can be associated with gluteus minimus and gluteus medius compromise. Impingement, whether involving implants, bone, or soft tissue are primarily secondary to the above factors, if osteophytes were properly trimmed at the index procedure. Correction of the incorrect variables is the primary goal of revision for instability and greatly preferable to using salvage options such as dual-mobility or constrained articulations which invoke additional concerns. Ultimately though, such salvage options are necessary if the cause of the instability cannot be determined or can be determined but not corrected. Bracing, while highly inconvenient and sometimes impractical for certain patients, still has a role in specific circumstances. Formal analysis of the unstable prosthetic reconstruction is the key to successful treatment

Altered distal radioulnar joint contact (DRUJ) mechanics are thought to cause degenerative changes in the joint following injury. Much of the current research examining DRUJ arthrokinematics focuses on the effect of joint malalignment and resultant degenerative changes. Little is known regarding native cartilage contact mechanics in the distal radioulnar joint. Moreover, current techniques used to measure joint contact rely on invasive procedures and are limited to statically loaded positions. The purpose of this study was to examine native distal radioulnar joint contact mechanics during simulated active and passive forearm rotation using a non-invasive imaging approach. Testing was performed using 8 fresh frozen cadaveric specimens (6 men: 2 women, mean age 62 years) with no CT evidence of osteoarthritis. The specimens were thawed and surgically prepared for biomechanical testing by isolating the tendons of relevant muscles involved in forearm rotation. The humerus was then rigidly secured to a wrist simulator allowing for simulated active and passive forearm rotation. Three-dimensional (3D) cartilage surface reconstructions of the distal radius and ulna were created using volumetric data acquired from computed tomography after joint disarticulation. Using optically tracked motion data and 3D surface reconstructions, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. The results of this study indicate that contact area was maximal in the DRUJ at 10 degrees of supination (p=0.002). There was more contact area in supination than pronation for both active (p=0.005) and passive (p=0.027) forearm rotation. There was no statistically significant difference in the size of the DRUJ contact patch when comparing analogous rotation angles for simulated active and passive forearm motion (p=0.55). The contact centroid moved 10.5±2.6 mm volar along the volar-dorsal axis during simulated active supination. Along the proximal-distal axis, the contact centroid moved 5.7±2.4 mm proximal during simulated active supination. Using the technique employed in this study, it was possible to non-invasively examine joint cartilage contact mechanics of the distal radioulnar joint while undergoing simulated, continuous active and passive forearm rotation. Overall, there were higher contact area values in supination compared with pronation, with a peak at 10 degrees of supination. The contact centroid moved volarly and proximally with supination. There was no difference in the measured cartilage contact area when comparing active and passive forearm rotation. This study gives new insight into the changes in contact patterns at the native distal radioulnar joint during simulated forearm rotation, and has implications for increasing our understanding of altered joint contact mechanics in the setting of deformity