Purpose. Addressing posterior tibial plateau fractures is increasingly recognized as an important prognostic factor for functional outcome. The treatment of posterior tibial plateau fractures is rather demanding and the implants are still standard, off-the-shelf implants. This emphasizes the need for a more thorough morphological study of the posterior tibial plateau, in order to treat these posterior fractures more adequately. We aimed to demonstrate anatomical variations of the tibia in order to develop better implants. Method. After approval of the ethical committee 22 historically available CT scans of intact left tibia”s were segmented using Mimics (Materialise, Belgium). In order to perform principal component analysis, corresponding meshes are necessary. Mesh correspondence was achieved by deforming one selected source tibia to every other target tibia, through non rigid registration. The non-rigid registration algorithm was based on the algorithm described by Amberg et al (ref). After performing the non-rigid registration, principal component analysis was performed in Matlab (Mathworks, USA). Results. The first 3 components account for 98,1% of the anatomical shape variation of the tibia. The first principal component accounts for 95,4, the second accounts for 1,6% and the third component accounts for the remaining 1,1% of variation. In the first principal component the most marked variation was the length and the shaft width. Shorter tibia”s have a steeper and more angled posterior medial and lateral plateau as where longer tibia”s have a more rounded posterior tibia plateau. On the distal end, the tip of the medial malleolus is more prominent in shorter tibia”s than in longer tibia”s. The orientation of the tibiofibular joint is directed more posteriorly in larger tibias where it is orientated more laterally in smaller tibia”s. The slope of the medial and lateral tibia plateau is not related to the length or width of the plateau. The second principal component shows a relationship between a valgus shaped tibia shaft and its relation to a relatively smaller medial plateau”s compared with straight tibia”s of the same length. Valgus shaped, small tibia shafts have more posteriorly tilted lateral plateau”s compared with straight, broad shafted tibias. The third principal component shows that an angular shaped posterior tibia plateau is related to a more increased anterior bowing. The increase in the posterior tilt is mostly marked in the medial tibia plateau. Conclusion. The majority of tibia shape variations is directly related to the length of the shaft. The clinically known varus and valgus deformations represent only a small percentage of the total variation. Nevertheless, their variation within the second component is large and has a direct relation to the morphology of the tibia plateau. This data coud furthermore be used to improve implant design

Introduction

Previous studies have demonstrated the need of accurate reduction of ankle syndesmosis. Measurement of syndesmosis is difficult on plain radiographs. Recently, a difference of 2mm in anterior and posterior measurements at incisura of the inferior tibio-fibular joint on CT has been described as a measure of malreduction (depicted as ‘G’ for ease of description). Our practice changed towards routine post operative bilateral CT following syndesmosis fixation to assess the reduction and identify potential problems at an early stage. The aim of this primarily radiological study was to determine if the use of bilateral cross sectional imaging brings additional benefit above the more conventional practice of unilateral imaging.

The “Knot of Henry” was dissected in 16 embalmed cadaveric feet to reveal the complex interconnections between flexor hallucis longus (FHL) and flexor digi-torum longus (FDL) tendons. Three distinct anatomical patterns were observed.

Tension was applied manually to FHL or FDL proximal to the Knot. Digit movement was different depending on the anatomical pattern.

FHL or FDL tendon transfer is an accepted technique to prevent progression of acquired plano-valgus deformity. In order to minimise donor deficit, we suggest the use of either FHL or FDL should be based on assessment of the anatomical pattern at the time of surgery.

Introduction

Although total hip arthroplasty is a very successful operation, complications such as: dislocation, aseptic loosening, and periprosthetic fracture do occur. These aspects have been studied in large populations for traditional stem designs, but not for more recent short stems. The design rationale of short stems is to preserve bone stock, without compromising stability. However, due to their smaller bone contact area, high peak stresses and areas of stress shielding could appear in the proximal femur, especially in the presence of atypical bone geometries. In order to evaluate this aspect, we quantified the stress distribution in atypical proximal femurs implanted with a commercially available calcar guided short stem.

The aim of this study was to discover if the ulnar styloid is sufficiently consistent in size, shape and position relative to other bony features of the ulna to be used as a reference in pre-operative planning of fixation of broken bones.

The comparison of size and shape (together known as form) between bones has recently been facilitated thanks to the advance of technologies designed to allow the comparison of the form of structures using anatomical landmarks.

This new class of methods is collectively known as geometric morphometrics. It eliminates the differences in location and rotation of landmark through registration that minimises the sum of squared deviations from each other after scaling. This is Procrustes registration. The residual size and shape information is amenable to statistical analysis. In the present application, the registered Procrustes landmarks are used to compute a mean (reference) shape. The individuals are then compared to this mean/ reference shape. Using principal components analysis (PCA) variations in shape are not only identi-fied, but also quantified. The identification of patterns of deviation from the mean shape is considerably enhanced through the use of 3-D visualistaions of the shape variations represented by the space of the PCA.

These analyses indicate that the ulnar styloid is suf-ficiently consistent in location to other anatomical landmarks that it could be used as a radiographic marker in preoperative planning.

More importantly, the analysis of this study indicates that the methods of geometric morphometrics are widely applicable to the analysis of 3-D variations in morphology facilitating the analysis and comparison of radiographs. A useful future application will be in the development of 3-D reference morphologies that will allow the surgeon to compare and contrast the morphology of a radiograph of a badly broken (comminuted) bone to a standard one. Eventually computer might assist the surgeon by geometrically and visually showing how and by how much the bone needs reduction. Similarly, applications to the the virtual comparison of diseased and healthy bones might allow quantative and visual comparisons that could aid diagnosis and planning.

Artificial bone models (ABMs) are commonly used in traumatology and orthopedics for training, education, research and development purposes. The aim of this study was to develop the first evidence-based generic Asian pelvic bone model and compare it to an existing pelvic model. A hundred clinical CT scans of intact adult pelvises (54.8±16.4 years, 161.3±8.3 cm) were acquired. They represented evenly distributed female and male patients of Malay (n=33), Chinese (n=34) and Indian (n=33) descent. The CTs were segmented and defined landmarks were placed. By this means, 100 individual three-dimensional models were calculated using thin plate spline transformation. Following, three statistical mean pelvic models (male, female, unisex) were generated. Anatomical variations were analyzed using principal component analysis (PCA). To quantify length variations, the distances between the anterior superior iliac spines (ASIS), the anterior inferior iliac spines (AIIS), the promontory and symphysis (conjugate vera) as well as the ischial spines (diameter transversa) were measured for the three mean models and the existing ABM. PCA demonstrated large variability regarding pelvic surface and size. Principal component one (PC 1) contributed to 24% of the total anatomical variation and predominantly displayed a size variation pattern. PC 2 (17.7% of variation) mainly exhibited anatomical variations originating from differences in shape. Female and male models were similar in ASIS (225±20 mm; 227±13 mm) and AIIS (185±11 mm; 187±10 mm), whereas differed in conjugate vera (116±10 mm; 105±10 mm) and diameter transversa (105±7 mm; 88±8 mm). Comparing the Asian unisex model to the existing ABM, the external pelvic measurements ASIS (22.6 cm; 27.5 cm) and AIIS (186 mm; 209 mm) differed notably. Conjugate vera (111 mm; 105 mm) and diameter transversa (97 mm; 95 mm) were similar in both models. Low variability of mean distances (3.78±1.7 mm) was found beyond a sample number of 30 CTs. Our analysis revealed notable anatomical variations regarding size dominating over shape and gender-specific variability. Dimensions of the generated mean models were comparatively smaller compared to the existing ABM. This highlights the necessity for generation of Asian ABMs by evidence-based modeling techniques

Variations in pelvic anatomy are a major risk factor for misplaced percutaneous sacroiliac screws used to treat unstable posterior pelvic ring injuries. A better understanding of pelvic morphology improves preoperative planning and therefore minimises the risk of malpositioned screws, neurological or vascular injuries, failed fixation or malreduction. Hence a classification system which identifies the clinically important anatomical variations of the sacrum would improve communication among pelvic surgeons and inform treatment strategy. 300 Pelvic CT scans from skeletally mature trauma patients that did not have pre-existing posterior pelvic pathology were identified. Axial and coronal transosseous corridor widths at both S1 and S2 were recorded. Additionally, the S1 lateral mass angle were also calculated. Pelvises were classified based upon the sacroiliac joint (SIJ) height using the midpoint of the anterior cortex of L5 as a reference point. Four distinct types could be identified:. Type-A – SIJ height is above the midpoint of the anterior cortex of the L5 vertebra. Type-B – SIJ height is between the midpoint and the lowest point of the anterior cortex of the L5 vertebra. Type-C – SIJ height is below the lowest point of the anterior cortex of the L5 vertebra. Type-D – a subgroup for those with a lumbosacral transitional vertebra, in particular a sacralised L5. Differences in transosseous corridor widths and lateral mass angles between classification types were assessed using two-way ANOVAs. Type-B was the most common pelvic type followed by Type-A, Type-C, and Type-D. Significant differences in the axial and coronal corridors was observed for all pelvic types at each level. Lateral mass angles increased from Types-A to C, but were smaller in Type-D. This classification system offers a guide to surgeons navigating variable pelvic anatomy and understanding how it is associated with the differences in transosseous sacral corridors. It can assist surgeons’ preoperative planning of screw position, choice of fixation or the need for technological assistance

A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA. 566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry. The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm. This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning

Objectives. Congenital cruciate ligament deficiency is a rare condition that may occur in isolation or in association with longitudinal limb deficiencies such as fibular hemimelia or proximal femoral focal deficiency. Often anomalies of the menisci and their attachments can be very abnormal and impact on surgical management by standard techniques. Arthroscopic surgical knee reconstruction is undertaken to improve symptomatic instability and/or to stabilise and protect the knee for future planned limb lengthening surgery. The aim of this study is to evaluate the arthroscopic findings of patients undergoing surgery for congenital cruciate ligament deficiency, and specifically to determine the frequency and types of meniscal anatomical variations seen in these cases. Methods. Patients undergoing surgery for congenital cruciate ligament deficiency were identified from a prospectively collated database. Diagnosis was confirmed through review of the clinical notes and imaging. Operative notes and 4K saved arthroscopic images and video recordings for these cases were reviewed. Results. Over a six-year period (July 2017 – September 2023), 42 patients underwent surgery for congenital ligament deficiency and tibiofemoral instability (45 surgical episodes). Median age of patients at time of surgery was 10 years (range 4 – 17 years). The most frequent diagnosis was congenital longitudinal limb deficiency syndromes in 27 cases, with the most frequent being fibular hemimelia. Isolated congenital ligament deficiency without any other associated extra-articular manifestations occurred in 11 cases. Absence of meniscal root attachments or hypertrophy of meniscofemoral ligaments acting as ‘pseudo-cruciates’ were seen in over 25% of patients. In isolated ACL deficiency these were injured causing onset of instability symptoms and pain following trauma. Often these abnormal structures required addressing to allow surgical reconstruction. Conclusions. Our findings demonstrate that there are often meniscal variations seen in association with congenital absence or hypoplasia of the cruciate ligaments. In these patients hypertrophied meniscofemoral ligaments may act as cruciate-like structures and play a role in providing a degree of sagittal plane stability to the knee. However, when the knee becomes unstable to the point that cruciate ligament reconstruction is indicated, these meniscal variants may often require stabilisation using complex meniscal root repair techniques or variations to standard cruciate ligament reconstruction techniques to accommodate the variant anatomy

Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability. Cite this article: Bone Jt Open 2022;3(3):268–274

Abstract. Objectives. Ultrasound speckle tracking is a safe and non-invasive diagnostic tool to measure soft tissue deformation and strain. In orthopaedics, it could have broad application to measure how injury or surgery affects muscle, tendon or ligament biomechanics. However, its application requires custom tuning of the speckle-tracking algorithm then validation against gold-standard reference data. Implementing an experiment to acquire these data takes months and is expensive, and therefore prohibits use for new applications. Here, we present an alternative optimisation approach that automatically finds suitable machine and algorithmic settings without requiring gold-standard reference data. Methods. The optimisation routine consisted of two steps. First, convergence of the displacement field was tested to exclude the settings that would not track the underlying tissue motion (e.g. frame rates that were too low). Second, repeatability was maximised through a surrogate optimisation scheme. All settings that could influence the strain calculation were included, ranging from acquisition settings to post-processing smoothing and filtering settings, totalling >1,000,000 combinations of settings. The optimisation criterion minimised the normalised standard deviation between strain maps of repeat measures. The optimisation approach was validated for the medial collateral ligament (MCL) with quasi-static testing on porcine joints (n=3), and dynamic testing on a cadaveric human knee (n=1, female, aged 49). Porcine joints were fully dissected except for the MCL and loaded in a material-testing machine (0 to 3% strain at 0.2 Hz), which was captured using both ultrasound (>14 repeats per specimen) and optical digital image correlation (DIC). For the human cadaveric knee (undissected), 3 repeat ultrasound acquisitions were taken at 18 different anterior/posterior positions over the MCL while the knee was extended/flexed between 0° and 90° in a knee extension rig. Simultaneous optical tracking recorded the position of the ultrasound transducer, knee kinematics and the MCL attachments (which were digitised under direct visualisation post testing). Half of the data collected was used for optimisation of the speckle tracking algorithms for the porcine and human MCLs separately, with the remaining unseen data used as a validation test set. Results. For the porcine MCLs, ultrasound strains closely matched DIC strains (R. 2. > 0.98, RMSE < 0.59%) (Figure 1A). For the human MCL (Figure 1B), ultrasound strains matched the strains estimated from the optically tracked displacements of the MCL attachments. Furthermore, strains developed during flexion were highly correlated with AP position (R = 0.94) with strains decreasing the further posterior the transducer was on the ligament. This is in line with previously reported length change values for the posterior, intermediate and anterior bundles of the MCL. Conclusions. Ultrasound speckle tracking algorithms can be adapted for new applications without ground-truth data by using an optimisation approach that verifies displacement field convergence then minimises variance between repeat measurements. This optimisation routine was insensitive to anatomical variation and loading conditions, working for both porcine and human MCLs, and for quasi-static and dynamic loading. This will facilitate research into changes in musculoskeletal tissue motion due to abnormalities or pathologies. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Aims. Accumulated evidence indicates that local cell origins may ingrain differences in the phenotypic activity of human osteoblasts. We hypothesized that these differences may also exist in osteoblasts harvested from the same bone type at periarticular sites, including those adjacent to the fixation sites for total joint implant components. Methods. Human osteoblasts were obtained from the acetabulum and femoral neck of seven patients undergoing total hip arthroplasty (THA) and from the femoral and tibial cuts of six patients undergoing total knee arthroplasty (TKA). Osteoblasts were extracted from the usually discarded bone via enzyme digestion, characterized by flow cytometry, and cultured to passage three before measurement of metabolic activity, collagen production, alkaline phosphatase (ALP) expression, and mineralization. Results. Osteoblasts from the acetabulum showed lower proliferation (p = 0.034), cumulative collagen release (p < 0.001), and ALP expression (p = 0.009), and produced less mineral (p = 0.006) than those from the femoral neck. Osteoblasts from the tibia produced significantly less collagen (p = 0.021) and showed lower ALP expression than those from the distal femur. Conclusion. We have demonstrated for the first time an anatomical regional variation in the biological behaviours of osteoblasts on either side of the hip and knee joint. The lower osteoblast proliferation, matrix production, and mineralization from the acetabulum compared to those from the proximal femur may be reflected in differences in bone formation and implant fixation at these sites. Cite this article: Bone Joint Res 2021;10(9):611–618

Functional deficient of the little finger flexor digitorum superficialis (FDS-V) is known to be present in our population. The aim of this study is to evaluate the prevalence of the absence of FDS-V function in the Hong Kong Chinese population. The association between FDS-V absence and various variables (age, gender, hand dominance, occupation, smoking status, plamaris longus absence) were evaluated. The effects on the grip power due to FDS-V absence were analyzed. The anatomical variations were studied by cadaveric study. The clinical and anatomical variations were correlated by MRI study. 152 adult Chinese men and women from age 18 to 65 were recruited randomly. Subjects with congenital abnormalities, history of hand injury, history of upper limb surgery or underlying neuromuscular diseases were excluded. This study has 3 different parts. The first part is a clinical survey to determine the prevalence of the absence of FDS-V function by both the standard test and the modified test. The second part is a cadaveric study to determine the anatomical variations of FDS-V tendon by cadaveric dissection. The third part of this study is to correlate the clinical findings with MRI study. Total 152 subjects were recruited with 51 male and 101 female, average age 37.6. The prevalence of the absence of FDS-V function by the standard test was 40.1% for right hand and 37.5% for left hand (38.8%). The prevalence of the absence of FDS-V function by the modified test was 9.2% on the right hand and 9.9% on the left hand (9.54%). The absence of FDS-V function was found more common to be bilateral than unilateral. This was found that 68.6% were bilateral by the standard test and 61% were bilateral by the modified test. The associations of functional FDS-V absence with various variables were insignificant. The effects of various variables on the grip power were analyzed using the multiple linear regression. Gender was1he only variable that had significant effects on the grip power for both the right and left hand. On either hand, the absence of Palmaris longus tendon and the absence of the FDS-V function had no significant effects on the grip power. Cadaveric study showed that the little finger FDS tendon was present in all 10 cadaveric hands. Abnormal muscle or tendon interconnection was not found. MRI study showed that there was hypoplastic tendon in subjects with absent FDS-V function. The prevalence of the absence of FDS-V function in the Hong Kong Chinese population was 38.8% by the standard test and 9.54% by the modified test. The absence of little finger FDS function has no significant effects on the functional status as quantified by the grip power. We can postulate that patients with little finger FDS tendon injury can have normal range of motion and hand function if the FDP tendon is intact

Introduction. An understanding of anatomic variability can help guide the surgeon on intervention strategies. Well-functioning thumb metacarpophalangeal joints (MCPJ) are essential for carrying out typical daily activities. However, current options for arthroplasty are limited. This is further hindered by the lack of a precise understanding of the geometric variation present in the population. In this paper, we offer new insight into the major modes of geometric variation in the thumb MCP using Statistical Shape Modelling. Methods. Ten participants free from hand or wrist disease or injury were recruited for CT imaging (Ethics Ref:14/LO/1059). 1. Participants were sex matched with mean age 31yrs (range 27–37yrs). Metacarpal (MC1) and proximal phalanx (PP1) bone surfaces were identified in the CT volumes using a greyscale threshold, and meshed. The ten MC1 and ten PP1 segmented bones were aligned by estimating their principal axes using Principal Component Analysis (PCA), and registration was performed to enable statistical comparison of the position of each mesh vertex. PCA was then used again, to reduce the dimensionality of the data by identifying the main ‘modes’ of independent size and shape variation (principal components, PCs) present in the population. Once the PCs were identified, the variation described by each PC was explored by inspecting the shape change at two standard deviations either side of the mean bone shape. Results. For the ten MC1s, over 80% of the variation was described by the first two PCs (Table 1). Figure 1 shows the effect of the variation in PC1. The majority of geometric variation of the ten PP1s was also described by the first two PCs, with PC1 describing 78.9%. Figure 2 shows the effect of this component on the mean bone geometry. Both the distal articulating surface (head) of the MC1 and the proximal articulating surface (base) of the PP1 vary in overall size. However, the MC1 head also varies in shape (curvature), whereas the PP1 base does not appear to undergo noticeable variation in shape. In this study population, smaller MC1 was observed to correlate with a flatter head, whereas the PP1 head shape did not vary with size. Discussion. The flatter MC1 head (smaller height-radius ratio) may have implications for MCPJ instability, and possibly for osteoarthritic degeneration. A recent study predicted similar trends for the first CMC joint. 2. Previous investigation also observed correlation between MC1 head curvature and MCPJ RoM. 3. , which may explain clinical observations of differing thumb movement strategies. This study used a convenience sample and cannot describe a full population's variability, though the high variance captured by only two PCs suggests adequate external validity amongst similar populations. Further confidence would be gained from studying the joint (i.e. single PCA containing both bones), and wider populations. Significance. These data: provide more precise description of anatomic variation; may offer insights into thumb movement strategies and MCPJ osteoarthritic degeneration. 4. ; and support implant design for individuals whose anatomy can bear an anatomic reconstruction. For any figures or tables, please contact the authors directly

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

Neurovascular injury during shoulder arthroplasty is uncommon and has been reported to occur in 1–4% of cases. The incidence of nerve abnormalities during intraoperative nerve monitoring during shoulder arthroplasty is substantially higher. However, the rate of false positives with nerve monitoring is high and the clinical significance of these intraoperative findings is unknown. Therefore, the clinical utility of intraoperative nerve monitoring is unproven. Regardless, experience with intraoperative nerve monitoring has allowed us to identify the times during the procedure when measurable nerve dysfunction is most common. Moreover, experience as well as familiarity with reported patient and anatomic risk factors may help reduce the incidence of neurovascular injury. Five rules that will likely help to reduce intraoperative nerve injuries include recognition of reported patient risk factors, knowledge of relevant anatomy and normal anatomic variations, intraoperative identification and protection of at-risk neurovascular structures, limitation of overall operative time and the amount of time with the arm in at-risk positions, and minimization of retraction force. It is likely not possible to completely avoid neurovascular injuries during TSA. However, by following these five rules, the risk of neurovascular injury can be minimised

Percutaneous fixation with iliosacral screws has been shown to be a safe and reproducible method for the management of certain posterior pelvic injuries. However, the method is contraindicated in patients with sacral anatomical variations and dysmorphism. The incidence and the pattern of S1 anatomical variations were evaluated in 61 volunteers (35 women and 26 men) using MRI scans of the sacrum. S1 dimensions (12 parameters) in both the transverse and coronal planes were recorded and evaluated. Individuals were divided in four groups based on the S1 body size and the asymmetry of dimensions on the transverse and coronal planes. In 48 (78.6%) patients, dimensions in both planes were symmetrical despite the varying size of the S1 body. In 9 (14.8%) patients, coronal plane dimensions were disproportionally smaller compared to those of the transverse plane with a varying size of S1 body making effective iliosacral screw insertion a difficult task. In 2 (3.3%) patients there was a combination of large transverse plane and small coronal plane dimensions, with large S1 body size. A preoperative imaging study of S1 body size and coronal plane dimensions and an intraoperative fluoroscopic control of S1 dimensions on the coronal plane are suggested for safe iliosacral screw fixation

Anatomical variation of Lisfranc mortise has been implicated in the susceptibility of Lisfranc fracture-dislocation. We investigated whether the variations in the dimensions of second metatarsal base makes the joint vulnerable to fracture dislocation. Patients and Methods: 31 normal (group A) and 23 injured (group B) foot x-rays were compared. The average age of patients was 33(range 16–64) years. Routine AP and 45 degree oblique foot x-rays were used to measure second metatarsal parameters such as L (length of second metatarsal) were measured on x-rays in both groups. Additionally D (height of base of second metatarsal in sagittal plane of foot) was measured in CT scans. Statistical analysis was performed to test the viability of the null hypothesis that states that the relationship of second metatarsal length and height at the base does not correlate with increased susceptibility of Lisfranc injury. Similar analyses of the relevant parameters at the second metatarsal mortice were also calculated. Results: Mean values of D, L and D/L were obtained in both groups. Statistically the value of D/L was found to be significantly different between injured group and normal group, with a P value of 0.03, while the values of length of second metatarsal itself was not significantly different between two groups (P=0.15). However, no significant correlation was noticed using other parameters of the second metatarsal mortice. Conclusion: Previously shallowness of the second metatarsal mortice was shown to be significantly correlated with increased risk of Lisfranc injury. However, this study suggests that dimensions of second metatarsal such as, depth/length of the second metatarsal significantly increase the risk of Lisfranc injury. In other words more slender metatarsal dimensions at its base carry increased risk to Lisfranc injury. Thus, anatomical variation at the base of the second metatarsal makes the Lisfranc joint susceptible to injury

Introduction. Femoral neck impingement occurs clinically in total hip replacements (THR) when the acetabular liner articulates against the neck of a femoral stem prosthesis. This may occur in vivo due to factors such as prostheses design, patient anatomical variation, and/or surgical malpositioning, and may be linked to joint instability, unexplained pain, and dislocation. The Standard Test Method for Impingement of Acetabular Prostheses, ASTM F2582 −14, may be used to evaluate acetabular component fatigue and deformation under repeated impingement conditions. It is worth noting that while femoral neck impingement is a clinical observation, relative motions and loading conditions used in ASTM F2582-14 do not replicate in vivo mechanisms. As written, ASTM F2582-14 covers failure mechanism assessment for acetabular liners of multiple designs, materials, and sizes. This study investigates differences observed in the implied and executed kinematics described in ASTM F2582-14 using a Prosim electromechanical hip simulator (Simulation Solutions, Stockport, Greater Manchester) and an AMTI hydraulic 12-station hip simulator (AMTI, Watertown, MA). Method. Neck impingement testing per ASTM F2582-14 was carried out on four groups of artificially aged acetabular liners (per ASTM F2003-15) made from GUR 1020 UHMWPE which was re-melted and cross-linked at 7.5 Mrad. Group A (n=3) and B (n=3) consisted of 28mm diameter femoral heads articulating on 28mm ID × 44mm OD acetabular liners. Group C (n=3) and D (n=3) consisted of 40mm diameter femoral heads articulating on lipped 40mm ID × 56mm OD 10° face changing acetabular liners. All acetabular liners were tested in production equivalent shell-fixtures mounted at 0° initial inclination angle. Femoral stems were potted in resin to fit respective simulator test fixtures. Testing was conducted in bovine serum diluted to 18mg/mL protein content supplemented with sodium azide and EDTA. Groups A and C were tested on a Prosim; Groups B and D were tested on an AMTI. Physical examination and coordination measurement machine (CMM) analyses were conducted on all liners pre-test and at 0.2 million cycle intervals to monitor possible failure mechanisms. Testing was conducted for 1.0 million cycles or until failure. An Abaqus/Explicit model was created to investigate relative motions and contact areas resulting from initial impingement kinematics for each test group. Results. Effects of kinematic differences in the execution of ASTM F2582-14 were observed in the four groups based on simulator type (Figure 1) and liner design. The Abaqus/Explicit FEA model revealed notable differences in relative motions and contact points (Figure 2) between specimen components i.e. acetabular liner, femoral head, and femoral stem throughout range of motion. Acetabular liner angular change within shell-fixtures, rim deformation, crack propagation, and metal-on-metal contact between acetabular shell-fixtures and femoral stems were observed as potential failure mechanisms (Figure 3) throughout testing. These mechanisms varied in severity by group due to differing contact stresses and simulator constraints. Significance. Investigating failure mechanisms caused by altered kinematics of in-vitro neck impingement testing, due to influences of simulator type and acetabular liner design, may aid understanding of failure mechanisms involved when assessing complaints/retrievals and influence future prosthetic designs. For any figures or tables, please contact the authors directly

Anatomical variations in the attachment between the tendon of the flexor hallucis longus (FHL) and of the flexor digitorum longus (FDL) are not clearly detailled in the medical literature. Twenty-four cadaver specimens were dissected and the distal anatomical relationship between the FHL and the FDL were analyzed and measured. There are three configurations of the attachment between the tendon of the FHL and of the FDL. The absence of a tendon link seems to be more common than has been published to date in the medical literature. We have also shown that the same patient may have a different configuration on each foot. Anatomical variations in the links between the tendon of the flexor hallucis longus (FHL) and of the flexor digitorum longus (FDL) are not clearly detailled in the medical literature. There are three configurations of links between the tendon of the FHL and of the FDL. The absence of a tendon link seems to be more common than has been published to date in the medical literature. A surgeon who wants to preserve the distal function of the FDL after transferring the proximal portion of the latter should perform surgical tenodesis initially or explore the FHL-FDL attachment and perform tenodesis when a type-3 configuration is discovered. We distinguish three different configurations of the distal link between the FHL and the FDL. In type 1, a tendinous band from the FHL is attached to the FDL (42%, 10/24). In type 2, a tendinous band from the FHL is attached to the FDL and another one from the FDL is attached to the FHL (42%, 10/24). In type 3, there is no attachment (17%, 4/24). In no case is there only an attachment from the FDL to the FHL. In four cadavers a different configuration was present on each foot. The diameter of the attachment compared with the “donor” tendon varied between 37 and 53%. Twenty-four intact cadaver specimens were dissected and the distal anatomical relationship between the FHL and the FDL were analyzed. The width of the tendons and their attachments were measured to the nearest half-millimetre