Object. Our purpose is to describe a new surgical technique, the transoral kyphoplasty, that we performed in 3 cases of tumors in C2. Materials and Methods. From February 2004 to January 2006 3 cases of C2 tumoral localizations did not show healing after 6 months of conservative treatments. To reduce pain and avoid both C2 collapse and prolonged immobilization transoral kyphoplasties were performed. Results. There were no complications and/or complaints related to the procedure. There were no C2 related symptoms or neurological problems. The first patient died 8 months after surgery due to unrelated causes. The second and the third are alive and, follow ups of 2 years and 8 months respectively, reveal good and pain-free cervical motion, with no findings regarding pathologic mobility/instability on X-ray and CT. Discussion. The management of tumors of the C2 body is still controversial. In cancer patients non-operative treatment could fail. In these cases the literature recommends internal fixation (anterior or posterior), percutaneous vertebroplasty, or transoral vertebroplasty [. 1. –. 4. ]. Anatomically, the transoral route is the most straightforward percutaneous access to the C2 body [. 4. ]. In our cases, after conservative treatment failure, we performed the transoral kyphoplasty to avoid major surgical procedures, and considering kyphoplasty an improvement of the vertebroplasty. While maintaining the normal cervical spine anatomy, and avoiding arthrodesis or fixation that reduce the cervical spine range of motion, in the thoracolumbar spine kyphoplasty versus vertebroplasty is correlated with a reduction in the complication rate [. 5. ]. Conclusions. Transoral kyphoplasty could be considered a safe, quick and effective treatment in reducing pain and avoiding vertebral collapse in patients with tumors in C2, not responding to non-operative treatment

Evaluation of the anatomical features, details of surgical technique and results of the THA in patients with CDH (type C1 and C2 by G. Hartofilakidis). From 2001 to 2016 years one surgical team performed 683 THA in patients with CDH. We retrospectively studied 561 total hip arthroplasties in 349 patients, follow-up rate was 82.1%, from 12 to 188 months (mean 69.4). The results were evaluated by clinical examination, X-rays analysis, Harris Hip Score. Unilateral high hip dislocation was observed in 175 patients (31.2%), in these cases often have underdeveloped half of the pelvis on the side of the dislocation. Type C1 was observed in 326 cases and type C2 – in 235 cases. Type C1 in comparison with C2 has less leg length discrepancy, developed shape of proximal femur, presence of supraacetabular osteophyte. The mean displacement of femoral head was 47.6 mm (from 29 to 55) for C1 and 63.4 mm (from 41 to 78) for C2. Average offset in C1 was 50.1 mm (37–63) and in C2 − 44.3 mm (34–52). Shortening osteotomy by T. Paavilainen performed in 165 cases (50.6%) with C1 dysplasia and in 235 cases (100%) with C2. The features of surgical technique were small size of the cups with obligatory additional screw fixation of the cup and small offset of the stems. The cup was positioned into the true acetabulum in 99.1% cases of C2 type, for C1 – only 69.0%). The cups size 44 mm were used in 97.3% cases for type C2 and in 78.6% cases for type C1. For shortening osteotomy in 76.3% cases Wagner Cone stems were used. Early complications included 9 dislocations (1.6%), 8 femoral nerve neuropathies (1.4%) and 3 infections (0.5%). There is no sciatic nerve palsy. Late complications included dislocation in two hips (1.1%), nonunion of the greater trochanter (8.4%), aseptic loosening of the femoral component − 2 (0.8 %), aseptic loosening of the cup − 11 (1.6%). Average Harris Hip score improved from 39.5 to 83.6 with unsignificant diffence between types C1 and C2 (from 37.3 to 81.4 and from 40.4 to 85.1 consequently). Revision rate was 2.1% for type C1 and 5.5% for type C2. Hip replacement surgery in patients with high hip dislocation is very challenging. Type C2 dysplasia has only one surgical option with good long-term results – placement of the cup into the true acetabulum and shortening osteotomy. Its advantages include leg length alignment and decreased risk of sciatic nerve injury. Type C1 dysplasia presents more heterogenic group of patients and allows to use several surgical options – different placement of the cup and surgical approach without shortening osteotomy. Functional results in patients with type C1 are a little bit worse in comparison with type C2, but C1 had less risk of complications. The main problem of shortening osteotomy by Paavilainen is delayed union and non-union of great trochanter

Objectives. As one of the heat-stable enterotoxins, Staphylococcal enterotoxin C2 (SEC2) is synthesized by Staphylococcus aureus, which has been proved to inhibit the growth of tumour cells, and is used as an antitumour agent in cancer immunotherapy. Although SEC2 has been reported to promote osteogenic differentiation of human mesenchymal stem cells (MSCs), the in vivo function of SCE2 in animal model remains elusive. The aim of this study was to further elucidate the in vivo effect of SCE2 on fracture healing. Materials and Methods. Rat MSCs were used to test the effects of SEC2 on their proliferation and osteogenic differentiation potentials. A rat femoral fracture model was used to examine the effect of local administration of SEC2 on fracture healing using radiographic analyses, micro-CT analyses, biomechanical testing, and histological analyses. Results. While SEC2 was found to have no effect on rat MSCs proliferation, it promoted the osteoblast differentiation of rat MSCs. In the rat femoral fracture model, the local administration of SEC2 accelerated fracture healing by increasing fracture callus volumes, bone volume over total volume (BV/TV), and biomechanical recovery. The SEC2 treatment group has superior histological appearance compared with the control group. Conclusion. These data suggest that local administration of SEC2 may be a novel therapeutic approach to enhancing bone repair such as fracture healing. Cite this article: T. Wu, J. Zhang, B. Wang, Y. Sun, Y. Liu, G. Li. Staphylococcal enterotoxin C2 promotes osteogenesis of mesenchymal stem cells and accelerates fracture healing. Bone Joint Res 2018;7:179–186. DOI: 10.1302/2046-3758.72.BJR-2017-0229.R1

Purpose of study. The vast majority of C2 ring fractures can be managed non-operatively but occasionally the situation precludes this and surgery is considered. Thus study reviews our indications and surgical options in this scenario. Methods. A retrospective review of patient folders and x-rays was performed of all patients with C2 traumatic spondylolisthesis that were managed surgically between 2003 and 2012. Demographic data, particularly indications for surgery, the options chosen and the clinical and radiological outcomes were analysed. Results. Six patients required surgery for a Traumatic Spondylolisthesis of the Axis during this period. Of these 6 cases, 2 were performed for failure of conservative treatment and the other 4 for associated injuries or condition (pregnancy). A variety of surgical methods were utilised including pars repair, C2-C2 posterior fusion and combined anterior C2/3 plating with posterior C1-3 fixation. Osseous healing was achieved in all patients in less than 6 months. There was one case that presented at 3 months post op with an adjacent level subluxation that required application of cones callipers until bony union. There were no infective complications, and no deterioration of neurological findings. Conclusion. Although the majority of Traumatic Spondylolisthesis of the Axis can be managed non-operatively, there are occasional non-spinal reasons to consider surgical stabilisation. There are many options but we would recommend a C2/3 fusion rather than pars repair due to the C2/3 disc trauma and inevitable ankylosis. This can be effectively performed from a posterior approach. NO DISCLOSURES

To describe a modification of the existing technique for C2 translaminar screw fixation that can be used for salvage in difficult cases. Bilateral crossing C2 laminar screws have recently become popular as an alternative technique for C2 fixation. This technique is particularly useful in patients with anomalous anatomy, as a salvage technique where other modes of fixation have failed or as a primary procedure. However, reported disadvantages of this technique include breach of the dorsal lamina and spinal canal, early hardware failure and difficulty in bone graft placement due to the position of the polyaxial screw heads. To address some of these issues, a modified technique is described. In this technique, the upper part of the spinous process of C2 is removed and the entry point of the screw is in the base of this removed spinous process. From October 2008 to March 2009, 6 patients underwent insertion of unilateral translaminar screws using our technique. The indications were: basilar invagination(three cases), C1/C2 fracture (two cases), tumour (one case). Age varied from 22 to 81 years (mean 48 years). All patients had post-operative x-ray and CT scan to assess position of the screws. Mean follow-up was 6 months. The screw position was satisfactory in all patients. There were no intraoperative or early postoperative complications. Our modification enables placement of bone graft on the C2 lamina and is also less likely to cause inadvertent cortical breach. Because of these advantages, it is especially suitable for patients with advanced rheumatoid arthritis with destruction of the lateral masses of C2 or as part of a hybrid construct in patients with unilateral high riding vertebral artery. This technique is not suitable for bilateral translaminar screw placement

In this biomechanical study of isolated porcine C2 vertebrae, antero-posterior forces were applied to potted specimens. Bipedicular fractures were generated in 25.4% of fifty-nine specimens (others fractured mostly through laminae). Bipedicular fractures were subsequently fixed under direct vision with trans-pedicular lag screws. These fixed specimens were then tested again. The mean ultimate tensile strength of the construct was 27.1% compared to the native bone’s fracture strength in the same specimen. This is a good model for hangman’s fracture, and is relevant to newer constructs that utilize C2 pedicle screws as part of a larger instrumentation procedure. Hangman’s fracture rarely needs internal fixation. However, if fixation is indicated the fracture can sometimes be directly fixed with trans-pedicular screws rather than fusing C1-C2 and committing to a great loss of neck range of motion. To our knowledge, the actual pullout strength of pedicle screws in C2 is previously unreported. Hence, we developed a laboratory model of hangman’s fracture by applying antero-posterior tensile force in fifty-nine porcine specimens that were stripped of soft tissues. The failure strength of the bone averaged approximately 3200 N, and subsequent fixation averaged to 27.1% of this value. Regardless of pre-hoc expectations, these values indicate that the screw purchase is strong enough to consider continued use of the procedure in repair of hangman’s fracture, fixation to C2 of multi-level constructs, and so forth. Multiple anterior and posterior screw procedures have been tested in the past, but to our knowledge the pullout strength of C2 pedicle screws has not been examined. Because the usage of C2 pedicle screws is growing in popularity, this biomechanical information is pertinent to work in traumatic, degenerative, and reconstructive procedures. Some limitations of the present study are that the specimens were porcine rather than human, and that only fixation to single vertebrae was examined. Funding: Dr Kaspar holds academic research grants from McMaster University and from The Physicians’ Services Incorporated (PSI) Foundation, the former of which was used to finance this project. There are no commercial grants or conflicts of interest

The treatment of type-II traumatic spondylolisthesis of C2 remains controversial. We reviewed the outcome of 16 patients treated between 2001 and 2003. As classified by Levine and Edwards, 14 patients sustained type-II fractures and two type-I injuries. There were no type-III injuries. All except one patient, who was injured playing rugby, were injured in motor vehicle accidents (four drivers, 10 passengers and one pedestrian). Eight patients had associated injuries. Thirteen patients were managed by means of a halo body jacket within 2 weeks of presentation for 5 to 9 weeks. One patient with a type-II injury was treated in an ABCO brace and those with type-I injuries in a Philadelphia collar. All patients showed evidence of radiological union within 12 weeks (mean 7.5 weeks). Flexion/extension views revealed no instability. All patients regained full flexion and extension clinically, but five had some limitation of rotation. One patient removed the halo body jacket himself. There were no pin-tract or neurological complications. Mean follow-up time was 13.5 months (3 to 27). Four patients exhibited late disc space changes at C2/3 on radiographs. Early patient mobilisation in a halo body jacket is an effective and safe management option for type-II C2 traumatic spondylolisthesis

Purpose: The purpose of this work was to determine the role of orthopaedic treatment as a function of initial criteria of instability and potential risk of secondary restabilisation after healing of the common anterior vertebal ligament in patients with bipediculated C2 fractures and to compare the results of surgical treatment using CE pediatric fixation of C1-C3 fractures associated with C1-C3 graft to those with C2-C3 arthrodesis using posterior screw plate fixation with a pedicular screw in C2. Material and methods: This was a retrospective analysis conducted in patients treated over a ten year period. There were 57 patients treated by two different orthopaedic surgery teams. There were 33 women and 24 mean, mean age 37 years with a maximum follow-up of 12 months. Clinical and radiographic findings were the same before treatment and at last follow-up. The surgical indication was for rupture of the common posterior vertebral ligament as assessed differently by two different surgical teams. Results: Orthopaedic treatment was given to 65% of the patients (72% and 62% for the two teams). Clinical outcome in these patients was good or excellent in 69% and 79% resepectively for the two teams. Surgical treatment was given in 35% of the cases. Cervical CD fixation produced 100% fair clinical results and 40% very good and good radiographic results with the other 60% being acceptable. For the C2-C3 plate with a pedicular screw in C2, the clinical outcome was good or very good in 53% with 34% fair and poor results and 73% good and very good and 27% poor radiographic results. Discusssion: This work demonstrated that indications or orthopaedic treatment can be extended, following the work by Roy-Cammille on the instability of these lesions introducting thus the notion of spontaneous anterior restabilisation due to healing of the common anterior vertebral ligament. For the choice of the technique, arthrodesis by cervical CD fixation remains a safe and sure technique despite the logical loss of C2-C3 rotation. Plate screw fixation with a C2 pedicular screw is more attractive but remains technically difficult

Purpose. The treatment of C2 fractures with collar, halo or surgery can all be justified depending on the patient. In our unit, primary treatment is with a halo: in a previous study presented at BASS we found an 85% fusion rate. In a follow on study, we wished to assess the outcome in those patients who underwent surgical treatment. Methods. The discharge logbook was examined retrospectively to identify patients who had posterior instrumentation for C2 fractures from 2008-2010 inclusive. Discharge summaries, clinic letters and radiology images/reports from PACS were analysed to obtain data regarding primary treatment, outcome, necessity for delayed treatment and radiological evidence of union. Results. Seven patients were identified who had surgery for C2 fracture. All 7 patients were treated with C1 and C2 lateral mass screws. In two of these patients additional lateral mass screws were inserted at C3. Due to patient preference, three of the seven patients underwent operative fixation without prior treatment in a halo. All three patients had evidence of bony union at the fracture site on subsequent radiological follow up. The remaining four patients were initially treated in a halo and had delayed surgery. After surgery two of these four patients had radiological evidence of bony union at the fracture site, one remained non-united and one patient has not yet been fully assessed. Conclusions. In this small series, operative fixation for C2 fracture lead to bony union at the fracture site in 5 out of 6 cases where full follow up was available. Interestingly, bony union at the fracture site may be an achievable objective even when surgery has been delayed or is not the primary treatment

To assess the outcome and safety of transarticular C1-C2 screw fixation. The clinical and radiological outcomes of 15 patients treated with posterior atlantoaxial transarticular screw fixation and posterior wiring was assessed at a minimum follow up of six months. Indications for fusion were rheumatoid arthritis in eight (instability in six and secondary degenerative changes in two), non union odontoid fracture four, symptomatic osodontoideum one, C1-C2 arthrosis one and irreducible odontoid fracture one. Fusion was assessed with plain x-rays including flexion – extension films. Twenty nine screws were placed under fluroscopic guidance. Bilateral screws were placed in 14 patients and a single screw in one patient. This patient had a single screw placed due to the erosion of the controlateral C2 pars by an anomolous vertebral artery. All patients had radiological union. Two screws (7%) were malpositioned, neither was associated with clinical sequelae. No neurological or vascular injuries were noted. Transarticular C1-C2 fusion yielded a 100% fusion rate. The risk of neurological or vascular injury can be minimised by thorough assessment of pre operative CT scans to assess position of the vertebral artery and use of intra operative lateral and AP fluroscopy

Aims: The optimal treatment of Type II odontoid fractures remains controversial. Our retrospective multicentric study of 114 odontoid process fractures documents experience with management of these fractures and discuss a new classification subtype II T and its surgical treatment. Methods: Fractures were defined using plain radiographs and CT reconstructions as per the Anderson- D’Alonzo classification. We have surgically treated 114 consecutive patients suffering from C2 odontoid fracture. 104 fractures were classified as Type II and 10 as Type III. Two cases of atypical, horizontal, mid-shaft odontoid process fractures were reported. In 55% an anterior two-screw fixation technique was chosen, remaining 45% underwent single-screw fixation. Results: One year follow-up data were available in 86.8% of cases and no major complications were found. Fusion rate calculated 6 months following surgery was 93%. We encountered cases, where the fracture line passes transversally through the middle of the shaft of odontoid process, below the level of transverse atlantal ligament, and we suggest to classify these cases as Type II T fractures. Also we analysed series of 75 surgically treated C1-2 instabilities and out of 11 pseudoarthrosis of the odontoid process 7 unrecognised Type II T fractures were found. Conclusions: Reported atypical fractures, newly classified as Type II T, are highly unstable (especially in rotations). In the authors’ opinion, two- screw technique should be the treatment of choice when internal fixation indicated

Goals: Advantage of the dorsal fixation of C1/2

Materials and Methods: From 01/2006 to 12/2006 22 patients with a traumatic fracture of C1/2 were operativly stabilized. The avarage age was 79 year (66–92). No neurological deficit. Diagnostic was always a CT-scan for classification of fracture typ. 7 patients were temporarily immobilized with HALO fixateur. Within th next 8 days final operation hab been carried out. 7 patients with Anderson fractures typ II were stabilized with open fixation from ventral (group 1). 4 Jefferson fractures and 2 combined C1/2 fractures were were stabilized with open fixation from dorsal (Magerl) (group 2). Percutanous fixation from dorsal was done in 5 patients with fractures of the atlas, 4 with Anderson fractures typ II (group3). Clinical and radiological follow up was done in 18 patients

Results: Duration for operation was in 64min in group1, 134min in group 2 and in 42min in group3. No neurological deficit or damage of A.vertebralis occurred. Blood loss was in group 1 and 3 under 50ml in group 2 750ml. In group3 one slightly dislocation of screw happened without need of revision. Movement of cervical spine was reduced in group 2 and 3. During follow up 3 of seven ventral stabilized Anderson fractures typ II (group1) were dislocated. Dorsal percutanous fixation for operatively revision was done.

Discussion: Percutanous dorsal transarticular screw fixation C1/2 is a challanging procedure for stabilization of atlantoaxial fractures. Main advantages compared to other operation techniques are less blood loss, short operation time, high rate of success.

Aims. In this study, we aimed to visualize the spatial distribution characteristics of femoral head necrosis using a novel measurement method. Methods. We retrospectively collected CT imaging data of 108 hips with non-traumatic osteonecrosis of the femoral head from 76 consecutive patients (mean age 34.3 years (SD 8.1), 56.58% male (n = 43)) in two clinical centres. The femoral head was divided into 288 standard units (based on the orientation of units within the femoral head, designated as N[Superior], S[Inferior], E[Anterior], and W[Posterior]) using a new measurement system called the longitude and latitude division system (LLDS). A computer-aided design (CAD) measurement tool was also developed to visualize the measurement of the spatial location of necrotic lesions in CT images. Two orthopaedic surgeons independently performed measurements, and the results were used to draw 2D and 3D heat maps of spatial distribution of necrotic lesions in the femoral head, and for statistical analysis. Results. The results showed that the LLDS has high inter-rater reliability. As illustrated by the heat map, the distribution of Japanese Investigation Committee (JIC) classification type C necrotic lesions exhibited clustering characteristics, with the lesions being concentrated in the northern and eastern regions, forming a hot zone (90% probability) centred on the N4-N6E2, N3-N6E units of outer ring blocks. Statistical results showed that the distribution difference between type C2 and type C1 was most significant in the E1 and E2 units and, combined with the heat map, indicated that the spatial distribution differences at N3-N6E1 and N1-N3E2 units are crucial in understanding type C1 and C2 necrotic lesions. Conclusion. The LLDS can be used to accurately measure the spatial location of necrotic lesions and display their distribution characteristics. Cite this article: Bone Joint Res 2024;13(6):294–305

Aims. Knee osteoarthritis (OA) involves a variety of tissues in the joint. Gene expression profiles in different tissues are of great importance in order to understand OA. Methods. First, we obtained gene expression profiles of cartilage, synovium, subchondral bone, and meniscus from the Gene Expression Omnibus (GEO). Several datasets were standardized by merging and removing batch effects. Then, we used unsupervised clustering to divide OA into three subtypes. The gene ontology and pathway enrichment of three subtypes were analyzed. CIBERSORT was used to evaluate the infiltration of immune cells in different subtypes. Finally, OA-related genes were obtained from the Molecular Signatures Database for validation, and diagnostic markers were screened according to clinical characteristics. Quantitative reverse transcription polymerase chain reaction (qRT‐PCR) was used to verify the effectiveness of markers. Results. C1 subtype is mainly concentrated in the development of skeletal muscle organs, C2 lies in metabolic process and immune response, and C3 in pyroptosis and cell death process. Therefore, we divided OA into three subtypes: bone remodelling subtype (C1), immune metabolism subtype (C2), and cartilage degradation subtype (C3). The number of macrophage M0 and activated mast cells of C2 subtype was significantly higher than those of the other two subtypes. COL2A1 has significant differences in different subtypes. The expression of COL2A1 is related to age, and trafficking protein particle complex subunit 2 is related to the sex of OA patients. Conclusion. This study linked different tissues with gene expression profiles, revealing different molecular subtypes of patients with knee OA. The relationship between clinical characteristics and OA-related genes was also studied, which provides a new concept for the diagnosis and treatment of OA. Cite this article: Bone Joint Res 2023;12(12):702–711

Objectives. Using a simple classification method, we aimed to estimate the collapse rate due to osteonecrosis of the femoral head (ONFH) in order to develop treatment guidelines for joint-preserving surgeries. Methods. We retrospectively analyzed 505 hips from 310 patients (141 men, 169 women; mean age 45.5 years . (sd. 14.9; 15 to 86)) diagnosed with ONFH and classified them using the Japanese Investigation Committee (JIC) classification. The JIC system includes four visualized types based on the location and size of osteonecrotic lesions on weightbearing surfaces (types A, B, C1, and C2) and the stage of ONFH. The collapse rate due to ONFH was calculated using Kaplan–Meier survival analysis, with radiological collapse/arthroplasty as endpoints. Results. Bilateral cases accounted for 390 hips, while unilateral cases accounted for 115. According to the JIC types, 21 hips were type A, 34 were type B, 173 were type C1, and 277 were type C2. At initial diagnosis, 238/505 hips (47.0%) had already collapsed. Further, the cumulative survival rate was analyzed in 212 precollapsed hips, and the two-year and five-year collapse rates were found to be 0% and 0%, 7.9% and 7.9%, 23.2% and 36.6%, and 57.8% and 84.8% for types A, B, C1, and C2, respectively. Conclusion. Type A ONFH needs no further treatment, but precollapse type C2 ONFH warrants immediate treatment with joint-preserving surgery. Considering the high collapse rate, our study results justify the importance of early diagnosis and intervention in asymptomatic patients with type C2 ONFH. Cite this article: Y. Kuroda, T. Tanaka, T. Miyagawa, T. Kawai, K. Goto, S. Tanaka, S. Matsuda, H. Akiyama. Classification of osteonecrosis of the femoral head: Who should have surgery?. Bone Joint Res 2019;8:451–458. DOI: 10.1302/2046-3758.810.BJR-2019-0022.R1

Aims. To determine the major risk factors for unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) and their interactions, using machine learning-based prediction algorithms and game theory. Methods. Patients who underwent surgery for ASD, with a minimum of two-year follow-up, were retrospectively reviewed. In total, 210 patients were included and randomly allocated into training (70% of the sample size) and test (the remaining 30%) sets to develop the machine learning algorithm. Risk factors were included in the analysis, along with clinical characteristics and parameters acquired through diagnostic radiology. Results. Overall, 152 patients without and 58 with a history of surgical revision following surgery for ASD were observed; the mean age was 68.9 years (SD 8.7) and 66.9 years (SD 6.6), respectively. On implementing a random forest model, the classification of URO events resulted in a balanced accuracy of 86.8%. Among machine learning-extracted risk factors, URO, proximal junction failure (PJF), and postoperative distance from the posterosuperior corner of C7 and the vertical axis from the centroid of C2 (SVA) were significant upon Kaplan-Meier survival analysis. Conclusion. The major risk factors for URO following surgery for ASD, i.e. postoperative SVA and PJF, and their interactions were identified using a machine learning algorithm and game theory. Clinical benefits will depend on patient risk profiles. Cite this article: Bone Joint Res 2023;12(4):245–255

No therapeutic strategy, administered in the early stage of osteoarthritis (OA), is fully able to block the degenerative and inflammatory progress of the pathology, whose only solution remains surgery. Aiming to identify minimally invasive therapies able to act on both degenerative and inflammatory processes, infiltrative treatments based on mesenchymal stem cells represent a promising solution due to their proliferative, immunomodulatory, anti-inflammatory, and paracrine ability. Accordingly, the aim of the present study was to investigate the performance of different cell therapies (stem cells from adipose tissue, ADSCs, stromal vascular fraction, SVF, and culture expanded, AECs vs negative control NaCl) in the treatment of OA. An in vivo model of early OA was developed in sheep knee (research protocol N.62/2018-PR date 29/01/2018 approved by the local Ethical Committee). Three and six months after the treatments injections, gross evaluation of articular surfaces (damage score, DS), histological (cartilage thickness, Th; fibrillation index, FI; collagen II content, C2) and mechanical assessment (elastic modulus, E; stress-relaxation time, τ) of cartilage were carried out. Due to the importance of the relationship between structure/composition (histology) and function (mechanics), this study investigated which of the revealed parameters were involved in such relation and how they were influenced by the level of degeneration and by the specific cell treatment, thus to better understand cell-tissue interaction. A statistically significant multi-variable linear regression model was found between τ and Th, FI, C2 (R2 0.7, p-value 8.39E-5). The relation was particularly strong between τ and C2 (p-value 7E-4), with a positive coefficient of 0.92. This is in agreement with literature, where a higher cartilage viscosity was related to a major content of collagen. By dividing the samples in two groups depending on cartilage damage, the more degenerated group (DS > 5) showed statistically significant lower C2 (p-value 0.0124) and τ (p-value 0.05), confirming that collagen content and viscosity decrease with OA grade increasing. Averaging the entire group of samples, the OA degeneration progressed between 3 and 6 months after, and despite, the treatment. But focusing on specific treatments, SVF and AECs differed from the general trend, inducing a higher amount of collagen at 6 months respect to 3 months. Moreover, articular cartilage treated by AECs and, overall, SVF showed a higher content of collagen and a major viscosity respect to the other treatments. We conclude that an injection of mesenchymal stem cells from stromal vascular fraction in early OA articulations could hinder the degenerative process, preserving or even restoring collagen content and viscosity of the articular cartilage

Abstract. Introduction. Intra-articular distal humerus OTA type C fractures are challenging to treat. When osteosynthesis is not feasible one can choose to do a primary arthroplasty of elbow or manage non-operatively. The indications for treatment of this fracture pattern are evolving. Objectives. We present our outcomes and complications when this cohort of patients was managed with either open reduction internal fixator (ORIF), elbow arthroplasty or non-operatively. Methods. Retrospective study to include OTA type C2 and C3 fracture distal humerus of 36 patients over the age of 50 years managed with all the three modalities. Patient's clinical notes and radiographs were reviewed. Results. Between 2016 and 2022, 21 patients underwent ORIF – group 1, 10 patients were treated with arthroplasty – group 2 and 5 were managed conservatively- group 3. The mean age of patients was 62 years in group 1, 70 years in group 2 and 76 years in group 3. The mean range of movement (ROM) arc achieved in the group 1 & 2 was 103 while group 3 was 68. At least follow up was 6 months. 5 patients in group 1 underwent metalwork removal and 2 patients in group 3 under arthroplasty. Conclusion. The outcomes of arthroplasty and ORIF are comparable, but reoperation rates and stiffness were higher in ORIF and conservative group. Surgeon choice and patient factors play important role in decision towards choosing treatment modality. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Odontoid fracture of the second cervical vertebra (C2) is the most common spinal fracture type in elderly patients. However, very little is known about the biomechanical fracture mechanisms, but could play a role in fracture prevention and treatment. This study aimed to investigate the biomechanical competence and fracture characteristics of the odontoid process. A total of 42 human C2 specimens (14 female and 28 male, 71.5 ± 6.5 years) were scanned via quantitative computed tomography, divided in 6 groups (n = 7) and subjected to combined quasi-static loading at a rate of 0.1 mm/s until fracturing at inclinations of −15°, 0° and 15° in sagittal plane, and −50° and 0° in transverse plane. Bone mineral density (BMD), specimen height, fusion state of the ossification centers, stiffness, yield load, ultimate load, and fracture type according to Anderson and d'Alonzo were assessed. While the lowest values for stiffness, yield, and ultimate load were observed at load inclination of 15° in sagittal plane, no statistically significant differences could be observed among the six groups (p = 0.235, p = 0.646, and p = 0.505, respectively). Evaluating specimens with only clearly distinguishable fusion of the ossification centers (n = 26) reveled even less differences among the groups for all mechanical parameters. BMD was positively correlated with yield load (R² = 0.350, p < 0.001), and ultimate load (R² = 0.955, p < 0.001), but not with stiffness (p = 0.070). Type III was the most common fracture type (23.5%). These biomechanical outcomes indicate that load direction plays a subordinate role in traumatic fractures of the odontoid process in contrast to BMD which is a strong determinant of stiffness and strength. Thus, odontoid fractures appear to result from an interaction between load magnitude and bone quality

Cranio-cervical connection is a well-established biomechanical concept. However, literature of this connection and its impact on cervical alignment is scarce. Chin incidence (CI) is defined as a complementary to the angle between chin tilt (CHT) and C2 slope (C2S) axes. This study aims to investigate the relationship between cervical sagittal alignment parameters and CI with its derivatives. A retrospective cross-sectional study carried out in a tertiary center. CT-neck radiographs of non-orthopedics patients were included. They had no history of spine related symptoms or fractures in cranium or pelvis. Images’ reports were reviewed to exclude those with tumors in the c-spine or anterior triangle of the neck. A total of 80 patients was included with 54% of them were males. The mean of age was 30.96± 6.03. Models of predictability for c2-c7 cobb's angle (CA) and C2-C7 sagittal vertical axis (SVA) using C2S, CHT, and CI were significant and consistent r20.585 (f(df3,76) =35.65, P ≤0.0001, r=0.764), r20.474 (f(df2,77) =32.98, P ≤0.0001, r=-0.550), respectively. In addition, several positive significant correlations were detected in our model in relation to sagittal alignment parameters. Nonetheless, models of predictability for CA and SVA in relation to neck tilt (NT), T1 slope (T1S) and thoracic inlet axis (TIA) were less consistent and had a significant marginally weaker attributable effect on CA, however, no significant effect was found on SVA r20.406 (f(df1,78) =53.39, P ≤0.0001, r=0.620), r20.070 (f(df3,76) =1.904, P 0.19), respectively. Also, this study shows that obesity and aging are linked to decreased CI which will result in increasing SVA and ultimately decreasing CA. CI model has a more valid attributable effect on the sagittal alignment in comparison to TIA model. Future investigations factoring this parameter might enlighten its linkage to many cervical spine diseases or post-op complications (i.e., trismus)