The persistence of quadriceps weakness represents a major concern following anterior cruciate ligament reconstruction (ACLR). The underlying adaptations occurring in the activity of spinal ...motoneurons are still unexplored. This study examined the discharge patterns of large populations of motor units (MUs) in the vastus lateralis (VL) and vastus medialis muscles following ACLR. Nine ACLR individuals and 10 controls performed unilateral trapezoidal contractions of the knee extensor muscles at 35%, 50% and 70% of the maximal voluntary isometric force (MVIF). High‐density surface electromyography (HDsEMG) was used to record the myoelectrical activity of the vasti muscles in both limbs. HDsEMG signals were decomposed with a convolutive blind source separation method and MU properties were extracted and compared between sides and groups. The ACLR group showed a lower MVIF on the reconstructed side compared to the contralateral side (28.1%; P < 0.001). This force deficit was accompanied by reduced MU discharge rates (∼21%; P < 0.05), lower absolute MU recruitment and derecruitment thresholds (∼22% and ∼22.5%, respectively; P < 0.05) and lower input–output gain of motoneurons (27.3%; P = 0.009). Deficits in MU discharge rates of the VL and in absolute recruitment and derecruitment thresholds of both vasti MUs were associated with deficits in MVIF (P < 0.05). A strong between‐side correlation was found for MU discharge rates of the VL of ACLR individuals (P < 0.01). There were no significant between‐group differences (P > 0.05). These results indicate that mid‐ to long‐term strength deficits following ACLR may be attributable to a reduced neural drive to vasti muscles, with potential changes in excitatory and inhibitory synaptic inputs.
Key points
Impaired expression and control of knee extension forces is common after anterior cruciate ligament reconstruction and is related to high risk of a second injury.
To provide novel insights into the neural basis of this impairment, the discharge patterns of motor units in the vastus lateralis and vastus medialis were investigated during voluntary force contractions.
There was lower knee extensor strength on the reconstructed side with respect to the contralateral side, which was explained by deficits in motor unit discharge rate and an altered motoneuronal input–output gain. Insufficient excitatory inputs to motoneurons and increased inhibitory afferent signals potentially contributed to these alterations.
These results further our understanding of the neural underpinnings of quadriceps weakness following anterior cruciate ligament reconstruction and can help to develop effective rehabilitation protocols to regain muscle strength and reduce the risk of a second injury.
figure legend Changes in activity of motor units underlying deficits in knee extension strength following anterior cruciate ligament reconstruction (ACLR). The behaviour of motor units was assessed by decomposing high‐density surface electromyographic signals that were recorded from the vasti muscles of ACLR and control soccer players during submaximal trapezoidal contractions. The lower knee extension strength of the reconstructed side with respect to the contralateral side was explained by deficits in motor unit recruitment and derecruitment thresholds, by deficits in motor unit discharge rate of the vastus lateralis and by an altered input–output gain of motoneurons. Synaptic alterations and changes at muscle unit level potentially contributed to changes in motor unit activity. Correction made on 15 November 2021, after first online publication: The two preceding sentences have been updated to provide greater clarity.
Abstract
Background
Anatomical variations of the attachment of medial meniscus are a common finding. However, anomalies of the posterior horn are extremely rare. Only two cases of posterior root ...anomaly have been described prior to the routine use of arthroscopy for evaluation and treatment of meniscal pathology. In this report, we present an anomaly of both the anterior and posterior roots of the medial meniscus that posed both a diagnostic and therapeutic dilemma.
Case presentation
The patient is young male soccer player who is currently 16 years of age and began having the atraumatic onset of pain and symptoms that limited performance starting at age 14 and was referred for failure of response to nonoperative treatment. Diagnostic arthroscopy revealed the presence of an anteromedial meniscofemoral ligament whereas the posterior root showed no bony attachment. The radiographic and arthroscopic findings are described. The clinical decision was made after to proceed with observation, reassurance, and gradual return to full activity with physiotherapy guidance.
Discussion and conclusion
The absence of injury, the mild complaints reported by the patient, his age, skeletal immaturity, and remaining growth led us to adopt a conservative approach to treating this anatomic variant and currently the patient is able to participate fully in sports without symptoms or restrictions.
The growing interest in the conservation of historic buildings encourages the development of water-repellent materials and methodologies to consolidate and/or protect stones. Recently, particular ...attention was devoted to composites of inorganic oxides nanoparticles and hybrid siloxane or silicone polymers. Here we present a study on the water repellence of a thin protective coating obtained through sol-gel process starting from Glymo and Dynasylan 40®, and loading the silicate matrix with nano-sized silica particles (Aeroxide LE1® -Degussa-Evonik). The coatings were applied to limestone, sandstone and granite samples. The silica nanoparticles have been characterized by XRD, the siloxane matrix through micro-Raman spectroscopy, while the surface morphology was examined by SEM. The efficacy of the treatments has been evaluated through static contact angle measurements and capillary water absorption. The optical appearance of the coatings was evaluated by colorimetric measurements. Nanoparticles at suitable concentration gave high values for the static contact angle (up to ∼ 150°), for all stone species even for four months exposure to atmospheric conditions. The coatings, in the water capillary absorption tests, however, behave as expected only for granite even if the long-term water direct contact reduces the hydrophobicity.
Background
To arthroscopically evaluate the incidence of lateral meniscal root avulsion (LMRA) and associated intra-articular injuries in patients undergoing anterior cruciate ligament (ACL) ...reconstruction.
Materials and Methods
From April 2014 to March 2017, 532 consecutive patients were diagnosed as having an ACL injury and underwent arthroscopic ACL reconstruction. The diagnosis of LMRA was made arthroscopically. The effects of gender, activity, grade of laxity, time from injury, and concomitant meniscal lesions were analyzed.
Results
Among 532 patients, 497 (93.4%) underwent primary ACL reconstruction and 35 (6.5%) underwent revision procedures. 383 were acute or subacute injuries (less than 6 months from injury to surgery) and 149 chronic (more than 6 months). Average age was 30.4 years (DS: ± 11.04); there were 422 (79.3%) males and 110 (20.6%) females. A LMRA associated with the ACL injury was detected in 72 cases (13.5%), with a significant prevalence observed in males (
χ
2
= 4.65;
P
= 0.031, statistically significant). In the 149 patients with a chronic injury, 27 patients had LMRA (18.1%), while 45 of the 383 patients with an acute or subacute injury had LMRA (11.7%). There was a tendency, albeit not significant (
χ
2
= 3.721;
P
= 0.054), for the prevalence to increase with time since the initial ACL injury. LMRA was significantly associated (
χ
2
= 7.81;
P
= 0.006) with a meniscocapsular tear of the posterior horn of the medial meniscus (ramp lesion). No other significant associations, such as with severity of A-P translation (as measured by KT-2000) or activity level, were detected.
Conclusion
LMRA is a relatively common injury associated with both acute and chronic ACL tears. A relatively high incidence in cases of chronic ACL insufficiency suggests that LMRAs do not heal spontaneously or that they may appear with time, even when absent at the time of the initial injury.
Level of evidence
Level III, cross-sectional study.
Purpose
Graft choice for primary anterior cruciate ligament reconstruction (ACL-R) is debated, with considerable controversy and variability among surgeons. Autograft tendons are actually the most ...used grafts for primary surgery; however, allografts have been used in greater frequency for both primary and revision ACL surgery over the past decade. Given the great debate on the use of allografts in ACL-R, the “Allografts for Anterior Cruciate Ligament Reconstruction” consensus statement was developed among orthopedic surgeons and members of SIGASCOT (Società Italiana del Ginocchio, Artroscopia, Sport, Cartilagine, Tecnologie Ortopediche), with extensive experience in ACL-R, to investigate their habits in the use of allograft in different clinical situations. The results of this consensus statement will serve as benchmark information for future research and will help surgeons to facilitate the clinical decision making.
Methods
In March 2017, a formal consensus process was developed using a modified Delphi technique method, involving a steering group (9 participants), a rating group (28 participants) and a peer-review group (31 participants). Nine statements were generated and then debated during a SIGASCOT consensus meeting. A manuscript has been then developed to report methodology and results of the consensus process and finally approved by all steering group members.
Results
A different level of consensus has been reached among the topics selected. Strong agreement has been reported in considering harvesting, treatment and conservation methods relevant for clinical results, and in considering biological integration longer in allograft compared to autograft. Relative agreement has been reported in using allograft as the first-line graft for revision ACL-R, in considering biological integration a crucial aspect for rehabilitation protocol set-up, and in recommending a delayed return to sport when using allograft. Relative disagreement has been reported in using allograft as the first-line graft for primary ACL-R in patients over 50, and in not considering clinical results of allograft superior to autograft. Strong disagreement has been reported in using allograft as the first-line graft for primary ACL-R and for skeletally immature patients.
Conclusions
Results of this consensus do not represent a guideline for surgeons, but could be used as starting point for an international discussion on use of allografts in ACL-R.
Level of evidence
IV, consensus of experts.
Amphiboles are an important family of rock forming minerals, whose identification is crucial in provenance studies as well as in many other fields of geology, archaeology and environmental sciences. ...This study is aimed to find a quick way to characterize Ca-amphiboles in the tremolite (Ca2Mg5Si8O22(OH)2)–ferro–actinolite (Ca2Fe5Si8O22(OH)2) series. Raman spectroscopy is established as technique to perform non-destructive and quick analysis, with micrometric resolution, able to give the composition in terms of Mg/(Mg + Fe2+) ratio. To exploit the method, a preliminary characterization is performed by Scanning Electron Microscopy coupled with Energy-dispersed X-ray Spectroscopy (SEM-EDS). Two independent methods to evaluate the composition from the Raman data (aiming to an accuracy of about 5%), using the low-wavenumbers part of the spectrum and the OH stretching bands, are developed. The application of the proposed method to micro-Raman mappings and the possible use of handheld Raman spectroscopy to have compositional information on Ca-amphiboles are discussed.
MicroRNAs (miRNAs) are short 20-22 nucleotide RNA molecules that act as negative regulators of gene expression via translational repression: they have been shown to play a role in development, ...proliferation, stress response, and apoptosis. The transcriptional regulator LRF (Leukemia/lymphoma Related Factor) has been shown to prevent p19ARF transcription and consequently to inhibit senescence in mouse embryonic fibroblasts (MEF). Here we report, for the first time, that LRF is post-transcriptionally regulated by miR-20a. Using a gene reporter assay, direct interaction of miR-20a with the LRF 3'UTR is demonstrated. To validate the interaction miR-20a/3'UTR LRF miR-20a was over-expressed, either by transient transfection or retroviral infection, in wild type mouse embryo fibroblasts and in LRF-null MEF derived from LRF knock-out mice. We observed LRF decrease, p19ARF increase, inhibition of cell proliferation and induction of senescence. The comparison of miR-20a activity in wt and LRF-null MEF indicates that LRF is the main mediator of the miR-20a-induced senescence and that other targets are cooperating. As LRF down-regulation/p19ARF induction is always accompanied by E2F1 down-regulation and increase of p16, we propose that all these events act in synergy to accomplish miR-20a-induced senescence in MEF. Senescence has been recently revaluated as a tumor suppressor mechanism, alternative to apoptosis; from this point of view the discovery of new physiological "senescence inducer" appears to be promising as this molecule could be used as anticancer drug.
The majority of knee arthroscopic procedures are performed with 30° scope while the 70° arthroscope is mainly used for surgery of posterior compartments. In the arthroscopic armamentarium, another ...scope, unknown to many surgeons, is also available: the 45° arthroscope. His field of view provides a wider intraoperative view than that of a 30° scope without the characteristic blind spot of a 70° scope. Therefore, the surgeon's orientation is not compromised. because the optic has always an element of forward vision. With these advantages, the 45° scope can be used in all knee surgical procedures without the need for having two scopes sterilized on the surgical table with less risk of contamination and less surgical time. The 45° scope may also be valuable for the arthroscopic surgery of other joints with the same advantages.
The popliteomeniscal fascicules (PMFs) provide the attachment of the lateral meniscus to the popliteus musculotendinous region, forming the floor and the roof the popliteal hiatus. In the second half ...of 1900's, some anatomic studies claim the important function of the PMF as stabilizers of the lateral meniscus; these anatomical structures work in conjunction with the popliteus musculotendinous unit to prevent excessive lateral meniscal movement and possible meniscus subluxation. A correct diagnosis of the PMFs pathology is crucial to establish the suitable surgical treatment for each patient. MRI is a well-established imaging technique in the musculoskeletal system and the frequency of recognition of normal PMF in the normal knees is high in almost all MRI studies. At day, the gold standard for diagnosis is the arthroscopic evaluation that allows the direct visualization of the popliteo-meniscal ligaments at popliteal hiatus and evaluation of lateral meniscal movements. For this reason if unstable condition of meniscus was suspected, arthroscopic observation with probing into the popliteo-meniscal fascicle area is essential for the identification of the fascicle tears. Despite many treatments have being proposed in literature since now there is high recurrence of knee locking after repair and it is fundamental to develop new surgical techniques in order to achieve better outcome.
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