Fatigue-induced Alterations of the Patellar Tendon in Elite Sprint Track Cyclists.

This study aims to investigate morphological and mechanical properties and echogenicity of the patellar tendon (PT) after acute fatigue-induced alterations in sprint track cyclists. Fourteen elite track cyclists participated in this study. The exercise protocol consisted of three maximal start accelerations (over a distance of 62.5 m), one maximal start acceleration (at both 125 m and 250 m), and sprints from the standing start. Immediately after testing all measurements, PT stiffness and thickness were set at 5-10-15-20 mm distal from the apex of the patella and 5-10 mm proximal to the tibial tuberosity. CSA was set at proximal, middle, and distal, while echogenicity was at proximal and distal points. The results showed significant increases in PT stiffness at all reference points after start acceleration (p<0.001). PT thickness showed similar results for stiffness, except for location placed at TT-5 (p<0.001). CSA increased significantly in proximal, middle, and distal regions (p<0.001), while echogenicity of the tendon increased in proximal and distal regions (p<0.001) after start acceleration. Regional-dependent alterations of PT thickness and stiffness may be related to anatomical and physiological mechanisms due to acute isometric contraction in the initial phase of standing start. Tendon echogenicity might be also useful in monitoring tendon mechanical properties and defining acute fatigue-induced changes.

The bone microstructure from anterior cruciate ligament footprints is similar after ligament reconstruction and does not affect long-term outcomes.

PURPOSE: The purpose of this study was to assess the quality of the bone tissue microstructure from the footprints of the anterior cruciate ligament (ACL) and its impact on late follow-up outcomes in patients who undergo anterior cruciate ligament reconstruction (ACLR). METHODS: The records of 26 patients diagnosed with a completely torn ACL who underwent ACLR were collected. During the surgery performed using the Felmet method, bone blocks from the native ACL footprints were collected. The primary measurements of the bone microstructure were made using a microtomographic scanner. In late follow-up examinations, a GNRB arthrometer was used. RESULTS: There was no significant difference in the bone microstructure assessed using micro-CT histomorphometric data according to the blood test results, plain radiographs, age or anthropometric data. There was no difference in the bone volume/total volume ratio or trabecular thickness in the area of the native ACL footprints. Routine preoperative examinations were not relevant to the quality of the bone microstructure. The elapsed time from an ACL injury to surgery had no relevance to the results of arthrometry. CONCLUSION: The similarities in the microstructure of bone blocks from ACL footprints from the femur and tibia allow the variable use of these blocks to stabilize grafts in the Felmet method. The bone microstructure is not dependent on the time from injury to surgery. Histomorphometric values of the structure of the femoral and tibial ACL footprints have no impact on the long-term stability of the operated knee joint. TRIAL REGISTRATION: The approval of the Bioethics Committee of the Silesian Medical Chamber in Katowice, Poland (resolution 16/2014) was given for this research. LEVEL OF EVIDENCE: II.

Description of Novel Molecular Factors in Lumbar DRGs and Spinal Cord Factors Underlying Development of Neuropathic Pain Component in the Animal Model of Osteoarthritis.

Osteoarthritis (OA) is one of the most common joint disorder, with pain accompanied by functional impairment, as the most pronounced clinical symptom. Currently used pharmacotherapy involves symptomatic treatment that do not always provide adequate pain relief. This may be due to concomitance of central sensitization and development of neuropathic features in OA patients. Here we performed studies in the animal model of OA to investigate of the neuropathic component. Intraarticular injection of monoiodoacetate (MIA, 1 mg) was used to induce OA in Wistar male rats. Development of pain phenotype was assessed by behavioral testing (PAM test and von Frey's test), while corresponding changes in dorsal root ganglia (DRGs L3-L5) and spinal cord (SC) gene expression were assessed by means of qRT-PCR technique. We also performed microtomography of OA-affected knee joints to correlate the level of bone degradation with observed behavioral and molecular changes. We observed gradually developing remote allodynia after MIA treatment, indicating the presence of neuropathic component. Our results showed that, among DRGs innervating knee joint, development of central sensitization is most likely due to peripheral input of stimuli through DRG L5. In SC, development of secondary hypersensitivity correlated with increased expression of TAC1 and NPY. Our studies provided molecular records on abnormal activation of pain transmission markers in DRG and SC during development of OA that are responsible for the manifestation of neuropathic features. The obtained results increase insight into molecular changes occurring in the neuronal tissue during OA development and may contribute to readdressing treatment paradigms.

Assessment of sheep knee joint after ACL replacement with Achilles tendon autograft and PLA-based implant.

In this study, we propose a new approach in the anterior cruciate ligament (ACL) replacement to provide stability and integration with bone tunnel. A polylactide (PLA)-based tubular implant was used to support the graft stabilization in femoral and tibial bones and to stimulate the healing process after (ACL) replacement on a sheep model. The ACL was replaced with an autologous Achilles tendon split graft. The tendon-to-bone healing in the model was analyzed after 6 and 12 weeks. Two groups of animals were compared, i.e. the group with the PLA-based implant used in the ACL replacement and the control group without the implant. The knee joints were mechanically and clinically evaluated, including the histopathology tests, to determine their stability and integrity. The results indicated that the bioresorbable PLA-based tubular implant may facilitate integration of the tendon graft with bone. Remodeling the allograft inside the implant improves the joint mobility from the first week of healing: no pathological changes were observed at the surgery site and in the animals' mobility. After 6 and 12 weeks of healing no significant changes in the mechanical parameters of the knee joint were observed, regarding the joint failure force, knee displacement, angular mobility range and joint stiffness. Relatively small values of the non-destructive tests in the knee displacement, already 6 weeks after surgery, indicated the early stabilization of the knee joint. The studies showed that the failure forces of knee joints after the ACL replacement with the PLA-based implant are lower than those of an intact joint, although their biomechanical features, including strain-at- failure, are similar. The biomechanical parameters of the knee joint were significantly improved due to the selected method of attaching the autograft ends to the femoral and tibial bone surfaces. After 12 weeks the intra-tunnel tendon-bone site with the PLA implant revealed the better tibia-femur joint mechanical stability, linear force-strain function and the decreasing strain-to-failure value, as compared to the control group.

Analysis of intercondylar notch size and shape in patients with cyclops syndrome after anterior cruciate ligament reconstruction.

BACKGROUND: Cyclops lesion is the second most common cause of extension loss after anterior cruciate ligament reconstruction. This study focused on the correlation between the anatomy of the intercondylar notch and the incidence of cyclops lesion. To determine whether the size and shape of the intercondylar notch are related to cyclops lesion formation following anterior cruciate ligament reconstruction according to magnetic resonance imaging (MRI) findings. METHODS: One hundred twenty-five (125) patients were retrospectively evaluated. The notch width index (NWI) and notch shape index (NSI) were measured based on coronal and axial MRI sections in patients diagnosed with cyclops syndrome (n = 25), diagnosed with complete anterior cruciate ligament (ACL) tears (n = 50), and without cyclops lesions or ACL ruptures (n = 50). RESULTS: Imaging analysis results showed that the cyclops and ACL groups had lower mean NWI and NSI values than the control group. Significant between-group differences were found in NSI (p = 0.0140) based on coronal cross-sections and in NWI (p = 0.0026) and NSI (p < 0.0001) based on axial sections. CONCLUSIONS: The geometry of the intercondylar notch was found to be associated with the risk of cyclops lesion formation and ACL rupture.

Stress fractures in uncommon location: Six case reports and review of the literature.

BACKGROUND: Individuals' interest in sports activities has been increasing, contributing to more stress fracture occurrences in uncommon locations on the skeleton. In this study, several cases of stress fractures in atypical locations are presented, and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored. Additionally, different causes of stress fractures, as well as various modalities of treatment, are highlighted. Other potential factors of stress fractures were identified by a literature review. CASE SUMMARY: Six cases of stress fractures in the calcaneus, intermediate cuneiform bone, sacrum, tibia (bilateral), navicular bone and femoral neck are presented, with different types of diagnostic imaging and treatments. All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines. CONCLUSION: The type of therapeutic procedure selected should depend on the specific clinical case, i.e., the patient's condition and level of physical activity.

Bioresorbable Stent in Anterior Cruciate Ligament Reconstruction.

The exact causes of failure of anterior cruciate ligament (ACL) reconstruction are still unknown. A key to successful ACL reconstruction is the prevention of bone tunnel enlargement (BTE). In this study, a new strategy to improve the outcome of ACL reconstruction was analyzed using a bioresorbable polylactide (PLA) stent as a catalyst for the healing process. The study included 24 sheep with 12 months of age. The animals were randomized to the PLA group (n = 16) and control group (n = 8), subjected to the ACL reconstruction with and without the implantation of the PLA tube, respectively. The sheep were sacrificed 6 or 12 weeks post-procedure, and their knee joints were evaluated by X-ray microcomputed tomography with a 50 µm resolution. While the analysis of tibial and femoral tunnel diameters and volumes demonstrated the presence of BTE in both groups, the enlargement was less evident in the PLA group. Also, the microstructural parameters of the bone adjacent to the tunnels tended to be better in the PLA group. This suggested that the implantation of a bioresorbable PLA tube might facilitate osteointegration of the tendon graft after the ACL reconstruction. The beneficial effects of the stent were likely associated with osteogenic and osteoconductive properties of polylactide.