Osteoarthritis (OA) is a chronic degenerative joint disease with cartilage degeneration, subchondral bone sclerosis, synovial inflammation and osteophyte formation. Sensory nerves play an important role in bone metabolism and in the progression of inflammation. This study explored the effects of capsaicin-induced sensory nerve denervation on OA progression in mice. This study was approved by the Institutional Animal Care and Use Committee. OA was induced via destabilization of the medial meniscus (DMM). Sensory denervation was induced by subcutaneous injection of capsaicin (90mg/kg) one week prior to DMM. One week after capsaicin injection, sensory denervation in the tibia was confirmed by immunofluorescent staining with calcitonin gene-related peptide (CGRP)-specific antibodies. Four weeks after DMM, micro-CT scans, histological analysis and RT-PCR tests were performed to evaluate OA progression. Statistical analysis was performed using SPSS 13. P values of less than 0.05 were considered statistically significant. Subcutaneous injection of capsaicin successfully induced tibial sensory denervation (n=3), which aggravated OA by increasing subchondral bone resorption. The Osteoarthritis Research Society International (OARSI) score of the capsaicin+DMM group (n=8) (11.81±2.92) was significantly higher (P=0.003) than the score of the vehicle+DMM group (n=8) (8.31±1.80). The BV/TV of the tibial subchondral bone in the capsaicin+DMM group (n=8) was 55.67%±3.08, which was significantly lower (P < 0 .001) than in the vehicle+DMM group (n=8) (86.22%±1.92). In addition, the level of expression of somatostatin in the capsaicin+DMM group (n=8) was lower than in the vehicle+DMM group (n=8) (P=0.007). Capsaicin-induced sensory denervation increased tibial subchondral bone resorption, reduced the expression of somatostatin and eventually exacerbated the existing cartilage degeneration in mice. Despite capsaicin is often used clinically to relieve OA pain, its safety is still controversial according to the OARSI guidelines for the non-surgical management of knee osteoarthritis. The findings of our study suggest that application of capsaicin, although effective in relieving pain, may accelerate the progression of existing OA

Introduction. The management of chronic wrist pain is a challenging clinical problem. Wrist denervation aims to achieve an improvement in pain through selective neurotomy, irrespective of cause. Numerous authors have reported their experience and demonstrated a range of clinical outcomes. No studies to date have reliably identified patient populations in whom denervation surgery is most likely to succeed. We aimed to establish and investigate a new approach, combining local anaesthetic injections with a uniquely tailored functional assessment by a hand therapist, to act as a tool to identify individuals in whom surgical denervation is more likely to yield benefit. Methods. We conducted a retrospective review of 17 patients who had undergone wrist denervation procedures following our method of pre-operative assessment and selection. Patients in whom denervation was combined with other diagnostic or therapeutic surgical procedures were excluded. Each patient underwent an initial assessment by a hand therapist in which pain and functional scores were recorded using the Patient Rated Wrist Evaluation (PRWE). Further unique assessments of function were made, tailored to the functional goals and requirements of each patient. Pain scores were measured for each task. Local anaesthetic injections were then administered around the nerves considered for neurotomy and the assessments were repeated. Patients who demonstrated clear improvements in pain and function underwent surgery. Post-operative assessments of pain and function were repeated. Results. Results were analysed using the Wilcoxon signed ranks test. There was a statistically significant improvement in pain following wrist denervation surgery (p=0.06) as well as an improvement in function as measured on PRWE (p=0.01). Furthermore, the degree of improvement following local anesthetic injection correlated with the degree of improvement seen after surgery (p=0.06). Conclusions. Regardless of underlying diagnosis, improvements in pain and function following our assessment and selection process correlated with improvements seen after denervation surgery

Our aim was to determine the effect of denervation on repair-associated mRNA levels in the MCL after partial tear. Cohorts of rabbits underwent partial MCL tear with or without concomitant femoral nerve transection. Ligaments were harvested, RNA extracted and RT-PCR was performed using rabbit-specific primers for repair-associated molecules at three days, two wks, six wks and sixteen wks post-injury. Angiogenesis genes MMP3, MMP13, matrix components Collagen I and III and growth factors TGF-ß and NGF mRNA levels were increased in the denervated group at two-weeks post-injury (p< 0.05). Denervation significantly alters mRNA levels during the early stages of rabbit MCL healing. To determine the effect of denervation on repair-associated mRNA levels in the injured medial collateral ligament (MCL). Previous experiments revealed that denervation impairs healing of the MCL. We hypothesized that denervation would decrease repair-associated mRNA levels in the injured MCL when compared with normally innervated injured MCL. Adult, skeletally mature female rabbits were assigned to one of four groups: unoperated control, femoral nerve transection alone (denervated controls), MCL partial tear and denervated MCL partial tear. At three days, two weeks, six weeks or sixteen weeks post-surgery, cohorts of six rabbits from each experimental group were killed. Control rabbits were assessed at two weeks. Ligaments were harvested, RNA extracted and RT-PCR was performed using rabbit-specific primers. In the denervated injury group, mRNA levels of angiogenesis genes MMP-3 and MMP-13, matrix components Collagen I and III and growth factors TGF-ß and NGF had all increased at two-weeks post-injury, in comparison to non-denervated (p< 0.05). We also found increased levels of MMP-3 and NGF mRNA in the denervated group at sixteen weeks post injury (p< 0.05). The mRNA levels of the housekeeping gene GAPDH were increased in the denervated group only at three days post injury (p< 0.05). Of note, TGF-ß mRNA levels were significantly decreased in the denervated group at three days post injury (p< 0.05). Contrary to our initial hypothesis, denervation increases mRNA levels for many important molecules during the early stages of MCL healing. Additional research will be required to explain how and why denervation impairs ligament healing. No previous study has shown that innervation regulates mRNA levels in healing ligament

Purpose of the study: There is no satisfactory surgical solution for symptomatic osteoarthritis of the elbow joint with preserved functional motion if arthroplasty is not indicated (age, functional demand). The same is true for resistant epicondylalgia. The joint denervation techniques applied for the wrist and proximal inter-phalangeal joints have demonstrated their efficacy. We conducted an anatomic study of elbow innervation as a preliminary step to the development of a standardized surgical procedure for complete denervation of the elbow compartment. Material and methods: The study was conducted on 15 right and left unprepared fresh cadaver specimens. A standardized dissection method was used. The terminal branches of the brachial plexus were dissected proximally to distally under magnification, from the root of the arm to the mid third of the forearm. Results: Innervation of the medial compartment arose: anteriorly, from one of the two capsuloperiosteal branches arising from the medial nerve; in the epitrochleo-olecraneal gutter, from capsular branches issuing from the trunk of the radial nerve at the root of the arm and running with the ulnar nerve. The innervation of the lateral compartment arose: anteriorly, from an inconstant capsular branch issuing from the musculo-cutaneous nerve arising 4 to 7 cm downstream from the joint space and running between the bones. In the other cases, this zone was innervated by a nerve branch coming from the dorsal cutaneous nerve of the forearm issuing from the radial nerve. This branch innervated the apex of the laeral epicondyle in all cases. The posterior part of the lateral compartment was constantly innervated by a branch arising from the radial nerve in the proximal part of the arm, running between the deep hed of the triceps and the vastus lateralis, giving rise of nerves innervating the joint and terminating in the body of the anconeus muscle. Discussion: Our study enabled the description of new sources of elbow innervation not reported by Wilhelm. Conclusion: This systematization study of elbow joint innervation is a preliminary step to the development of a complete procedure for unicompartmental lateral or medial denervation of the elbow joint. The fields of application are the treatment of symptomatic osteoarthritis of the elbow joint in patients with preserved joint motion and resistant epicondylalgia

Lumbar facet joint pain cannot be reliably diagnosed clinically, the International Spinal Injection Society recommends two diagnostic local anaesthetic blocks before radiofrequency (RF) denervation [. 1. ]. Scoring systems may improve diagnostic accuracy. The two most popular scores disagree on the interpretation of pain induced by extension/rotation:. ‘Cochin Criteria’ [. 2. ]: pain on extension/rotation _ not facet joint problem. Helbig & Lee [. 3. ]: pain on extension/rotation _ facet joint problem. Methods: Retrospective study of all patients who had RF denervations of the lumbar facet joints in 2004. Patients were selected clinically and did not undergo diagnostic blocks. Cochin criteria, Helbig & Lee scores, work status, and outcome were taken from the case notes. Likelihood ratios were calculated for the scores, their individual components, and work status. Results: 145 patients underwent RF facet joint denervation, for 127 all data was available. In 68 patients the procedure was successful (53.5%). Conclusion: Neither the Cochin Criteria nor the Helbig & Lee score can predict the response to radiofrequency denervation of the lumbar facet joints. Pain on extension/rotation weakly indicates a poor response to facet joint denervation. X-rays do not help with the diagnosis. Social factors may be more important than clinical signs

Aims. A systematic review of the available literature comparing the outcomes of radiofrequency denervation to sham procedure in treating chronic low back pain caused by lumber zygapophysial joint pathology. Methods. Medline and EMBASE databases were searched for English language articles from 2005 to July 2010. Articles were considered for review if they satisfied the inclusion criteria: Randomised Controlled Trials(RCT) comparing radiofrequency neurotomy(RFN) to a ‘placebo’ procedure in patients with chronic low back pain caused by facet joint osteoarthritis. Adult patients of both sexes above 17 years of age who complained of continuous low back pain for more than 6 months with focal tenderness over the facet joints. Outcome measures of interest are pain improvement, physical activity, analgesic use, quality of life variables, range of motion of the lumbar spine and hip movement. Critical appraisal of the selected studies was carried out using the CASP appraisal tool for RCT. Results. Two articles were identified. Both demonstrated a statistically significant improvement in the pain (p<0.05) using a visual analogue scale in the RFN group compared to the sham procedure. Only one trial demonstrated a corresponding reduction in analgesic use. There was no consensus of improvement of quality of life factors in either study as compared to placebo. Conclusion. Radiofrequency denervation is better than sham procedure in treating pain caused by facet joint osteoarthritis with minimal adverse effects in the short term. A higher powered trial using a larger cohort and longer follow up is required to resolve some of the equivocal results. Conflicts of Interest. None. Source of Funding. None

Percutaneous radiofrequency neurotomy of the lumbar medial branch is a widely accepted treatment for pain of the lumber intervertebral joints. However its success rate has varied among authors. One reason for this inconsistency is the lack of method for objective evaluation of whether the nerve has been sufficiently denervated or not. This study has made possible real time and accurate monitoring of whether electrocauterization is properly executed or not. The subjects were 50 patients with law back pain persisting for 3 months or longer in whom facet block or medial branch block of posterior ramus was only temporarily effective. They ranged in age from 19 to 76 years (mean 54 years) and were followed up for 1 year to 7 years and 1 month (mean 2 years and 9 months). In our percutaneous radiofrequency neurotomy, the target point of denervation is defined as the groove between the mammillary process and accessory process (1) and complex muscle action potentials (CMAPs) of multifidus muscles are used as an index for objective evaluation of the effects of denervation. Improvements were observed immediately after the treatment in 39 patients (78%). The effects of this treatment, once attained, remained over a long period, and the duration of effects was 18–20 months as estimated by the cumulative success rate calculated using the Kaplan-Meyer method. Patients must be carefully selected for percutaneous radiofrequency neurotomy to be consistently effective, all the more because the procedure is simple. However, it is a reliable method for denervation of the lumbar medial branch and long-term relief from pain can be expected. This therapy, therefore, is an effective alternative for the treatment of chronic pain due to lumbar intervertebral arthropathy that resists conservative treatments and disturbs daily living

Aims: To assess the paraspinal muscle innervation and endurance in LSSMethods: Study included 25 patients with clinically and radiologically diagnosed LSS. Electromyography (EMG) of the paraspinal muscles was performed at the L3 to S1 levels bilaterally using a concentric needle. At least 20 insertions were analysed from each muscle to detect abnormal spontaneous activity associated with axonal damage (þbrillation potentials, positive sharp waves and complex repetitive discharges). Paraspinal muscle activity during trunk ßexion-extension movement and muscle endurance during dynamic isoinertial back endurance test were assessed by surface EMG. Muscle fatigue was calculated using mean power frequency (MPF) analysis. Results: Abnormal þndings in needle EMG of the paraspinal muscles were observed in 18 out of the 22 (81.8%) examined patients. Abnormal ßexionextension activation of the paraspinal muscles was observed in all examined patients. The MPF change was signiþcantly smaller than in previously evaluated healthy subjects and non-speciþc CLBP patients (P< 0.001) not suffering from symptoms of LSS. Para-spinal muscle fatigability was not associated with the denervation of the muscles. Conclusions: Denervation and abnormal activation of lumbar paraspinal muscles are frequent þndings in non-operated LSS patients. The paraspinal muscle endurance of the patients was unexpectedly good

Percutaneous radiofrequency facet joint denervation (RFJD) has been used increasingly since being described by Shealy1 for the non-surgical treatment of chronic low back pain. Extensive literature exists on this technique with a number of randomised control studies suggesting efficacy against Placebo2,3. However, the efficacy and reliability of repeat RFJD for chronic back pain is unknown. A prospective study was carried out on a consecutive series of 57 patients undergoing repeat lumbar RFJD between 2004 & 2006. 57 consecutive patients treated by the senior author (OLO) between April 2004–June 2006 were included in a prospective analysis using a visual analogue score (VAS) and the low back outcome score (LBOS). All 57 participants completed a telephone questionnaire at follow up. There were no complications. At a median average follow up of 14 months overall, clinical outcomes demonstrated moderate improvement in the majority of patients with poor rating at LBOS decreasing from 54.3% pre- to 40.3% post-RFJD. The overall degree of satisfaction was 77.2%. The overall median duration of pain relief was 10 months. Our study suggests that repeat RFJD appears to have reliable and satisfactory results when repeated with most patients reporting a high degree of satisfaction and with the clinical outcome similar to the initial procedure

Aim of the study: The evaluation of denervation efficiency in the treatment of the arthritis of the base of the thumb. Material and method. Between 2001– 2004, 15 patients were surgically treated for arthritis of the basis of the thumb. There were all females of an average age of 53 years. In all patients the procedure was done ambulatory under local anesthesia. After completing a protocol form, regarding pain motion and power of the thumb, an incision was made at the level of the wrist crease extended from the level of FCR to the level of the 2nd extensor compartment. Through this incision the articular branches which conform the studies of Wilhem and Fusche supply the 1st CMC joint were divided. A supplementary incision for the first intermetacarpal space was made. The patients were free to return to their activities the third postoperative day and they were reviewed after 3, 6, 12, 24 months by an independent doctor. Their data were also recorded conform the protocol. Results: Twelve patients out of 15 had excellent improvement of their strength. Pinch and grip power was doubled. Mobility of the thumb according to Kapanji scale was improved in all cases. Pain was reduced in 65% average. The patients were satisfied from the operation. There was one patient with poor improvement and two patients who never shown up at the follow-up. As the last were at the beginning of our learning curve we think that could have a less satisfactory result. Discussion: The method is simple with minimal impact to the patient activity or life. It gives good results in 65% –75% and leaves further operative procedures possible. Although there not enough data yet for this procedure and our number of cases is small with short follow-up we believe that it is a nice procedure, it satisfies both the patient and the surgeon regarding the overall improvement of mobility and pain

Introduction. Degenerative meniscal tears are the most common meniscal lesions, representing huge clinical and socio-economic burdens. Their role in knee osteoarthritis (OA) onset and progression is well established and demonstrated by several retrospective studies. Effective preventive measures and non-surgical treatments for degenerative meniscal lesions are still lacking, also because of the lack of specific and accurate animal models in which test them. Thus, we aim to develop and validate an accurate animal model of meniscus degeneration. Method. Three different surgical techniques to induce medial meniscus degenerative changes in ovine model were performed and compared. A total of 32 sheep (stifle joints) were subjected to either one of the following surgical procedures: a) direct arthroscopic mechanical meniscal injury; b) peripheral devascularization and denervation of medial meniscus; c) full thickness medial femoral condyle cartilage lesion. In all the 3 groups, the contralateral joint served as a control. Result. From a visual examination of the knee joint emerged a clear difference between control and operated groups, in the menisci but also in the cartilage, indicating the onset of OA-related cartilage degeneration. The meniscal and cartilaginous lesions were characterized by different severity and location in the different groups. For instance, a direct meniscal injury caused cartilaginous lesions especially in the medial part of the condyles, and the other approaches presented specific signature. Evaluation of scoring scales (e.g. ICRS score) allowed the quantification of the damage and the identification of differences among the four groups. Conclusion. We were effectively able to develop and validate a sheep model of meniscal degeneration which led to the onset of OA. This innovative model will allow to test in a pre-clinical relevant setting innovative approaches to prevent meniscal-related OA. Funding. Project PNRR-MAD-2022-12375978 funded by Italian Ministry of Health

The August 2014 Spine Roundup. 360 . looks at: rhBMP complicates cervical spine surgery; posterior longitudinal ligament revisited; thoracolumbar posterior instrumentation without fusion in burst fractures; risk modelling for VTE events in spinal surgery; the consequences of dural tears in microdiscectomy; trends in revision spinal surgery; radiofrequency denervation likely effective in facet joint pain and hooks optimally biomechanically transition posterior instrumentation

Background: Progression of fatty infiltration of the suscapularis muscle subsequent to total shoulder arthroplasty is frequent and may be an underestimated problem. The approach with osteotomy of the lesser tuberosity led to consistent bone to bone healing with neither retraction nor overtensioning of the musculotendinous unit. However, in a previous study, fatty infiltration of the subscapular muscle had progressed at least by one stage in 45% of the patients’ shoulders. We hypothesized that anterior approach to the shoulder joint with release of the subscapularis muscle would lead to a direct or indirect subclinical damage of the subscapular nerve and would be an explanation for the progression of fatty infiltration of the muscle. Methods: Nine Shoulders in eight consecutive patients had received a total shoulder arthroplasty using an anterior approach with osteotomy of the lesser tuberosity. The mean age at time of operation was 67 years. Patients were followed clinically including the Constant score and a detailed neurological examination, as well as radiographically with pre–and postoperative MRI’s, CT’s and standard radiographs at 6–and 12 months thereafter. Neurophysiological assessment was performed using a new pre–intra–and postoperative electromyographic technique for the subscapular muscle. Fibrillation and sharp waves as spontaneuous activities of the motor unit potentials (MUP) indicated direct signs of denervation. Incomplete interference patterns (IP’s) indicated an incomplete innervation pattern as an indirect sign of denervation. Results: After a one year follow up, 89% of the patients were very satisfied or satisfied with the result. The relative Constant Score improved from an average of 50 percent preoperatively to an average of 96 percent postoperatively (p=0,008). That corresponds to a postoperative subjective Shoulder value of 89 percent. From preoperative to 6–and 12-months postoperative, the average degree of fatty infiltration of the subscapular muscle progressed in an almost significant extent (0.6, 1.1, and 1.6 respectively; p=0.056). Intra–and postoperatively, there were neither fibrillations and sharp waves of the MUP’s as direct signs, nor incomplete (IP’s) of the motor unit of the subscapular nerve as indirect signs of denervation. Conclusion: Total Shoulder Arthroplasties perfomed by an anterior approach using an osteotomy of the lesser tuberosity yields good results with a high satisfaction rate. Comparable to our previous study, there are signs of progression of fatty infiltration of the subscapularis muscle within the first year subsequent to total shoulder arthroplasty. However, there were no signs of direct or indirect subclinical damage of the subscapular nerve during total shoulder arthroplasty

While a tourniquet is traditionally used to obtain a dry field during primary TKA (and is also thought to reduce perioperative blood loss), adverse effects of tourniquet use have been reported. Avoiding routine use of the tourniquet during TKA can minimise certain complications while improving the quality of the early result. Most studies of TKA with and without tourniquet show little difference in all forms of blood loss except for intraoperative. Some studies even show less overall blood loss in groups without tourniquet use. Modern techniques to minimise intraoperative loss have included topical treatments, systemic medications, as well as a bipolar tissue sealer. Visualisation of bleeding vessels and their management intra-operatively can substantially reduce early post-op hemarthrosis. Tourniquet use has also been related to post-operative thigh pain. This is a negative aspect of tourniquet use that can interfere with physical therapy and rehabilitation. Occasionally it can be a significant factor in post-op recovery. Data supports the fact that avoiding a tourniquet or at least reducing pressure to the minimum necessary may help to reduce post-operative thigh pain. Ischemia and tissue damage can affect neuromuscular function and rehabilitation following TKA. The time necessary to achieve straight leg raising and knee flexion is delayed by tourniquet use during TKA. Compressive nerve injury also may result in secondary effects of denervation on distal tissues. This denervation can delay recovery of blood flow and increase vessel spasm, hemorrhage and edema. The degree of dysfunction is related to the magnitude of tourniquet compression. Tension in the lateral retinaculum is directly affected by tourniquet use. Observations from these studies would indicate that lateral release should be performed only if found necessary after tourniquet deflation in order to minimise the potential morbidity that accompanies this procedure. Although thromboembolic events can occur during TKA without, tourniquet use is associated with more frequent events when it is used. Finally, it is prudent to avoid the use of a tourniquet in patients with vascular calcifications around the knee or abdomen due to advanced arteriosclerosis, previous bypass grafts, or reduced limb or tissue blood supply for any reason. Routine TKA with minimal tourniquet use greatly simplifies its performance in those settings where it is contra-indicated

While a tourniquet is traditionally used to obtain a dry field during primary TKA (and is also thought to reduce peri-operative blood loss), adverse effects of tourniquet use have been reported. Avoiding routine use of the tourniquet during TKA can minimise certain complications while improving the quality of the early result. Most studies of TKA with and without tourniquet show little difference in all forms of blood loss except for intra-operative. Some studies even show less overall blood loss in groups without tourniquet use. Modern techniques to minimise intra-operative loss have included topical treatments, systemic medications, as well as a bipolar tissue sealer. Visualisation of bleeding vessels and their management intra-operatively can substantially reduce early post-op hemarthrosis. Tourniquet use has also been related to post-operative thigh pain. This is a negative aspect of tourniquet use that can interfere with physical therapy and rehabilitation. Occasionally it can be a significant factor in post-op recovery. Data supports the fact that avoiding a tourniquet or at least reducing pressure to the minimum necessary may help to reduce post-operative thigh pain. Ischemia and tissue damage can affect neuromuscular function and rehabilitation following TKA. The time necessary to achieve straight leg raising and knee flexion is delayed by tourniquet use during TKA. Compressive nerve injury also may result in secondary effects of denervation on distal tissues. This denervation can delay recovery of blood flow and increase vessel spasm, hemorrhage and edema. The degree of dysfunction is related to the magnitude of tourniquet compression. Tension in the lateral retinaculum is directly affected by tourniquet use. Observations from these studies would indicate that lateral release should be performed only if found necessary after tourniquet deflation in order to minimise the potential morbidity that accompanies this procedure. Although thrombo-embolic events can occur during TKA without, tourniquet use is associated with more frequent events when it is used. Finally, it is prudent to avoid the use of a tourniquet in patients with vascular calcifications around the knee or abdomen due to advanced arteriosclerosis, previous bypass grafts, or reduced limb or tissue blood supply for any reason. Routine TKA with minimal tourniquet use greatly simplifies its performance in those settings where it is contra-indicated

Many authors believe that patellar resurfacing decreases the incidence of anterior knee pain. We analysed the results of 98 of our own patients (103 knees). Over the past two years, we performed total knee arthroplasty on 23 men (one bilateral) and 75 women (four bilateral). None of the patellae were replaced, but we carefully removed osteophytes, debrided the patella, and performed a thorough peripatellar synovectomy and circumpatellar cautery denervation. All patients on our database were telephoned, and those who reported pain were examined independently by a consultant and a registrar. If there was any controversy about the site of the pain, a third surgeon saw the patient. No patient had pain severe enough to warrant revision surgery. Only two (2%) had anterior knee pain, and in neither of them was it marked. We do not know whether our favourable results are attributable to the peripatellar synovectomy and/or circumpatellar cautery denervation. While we concede that a control study of patients who have undergone patellar resurfacing might be necessary before a firm conclusion can be drawn, we question whether, with such a low incidence of patellar problems, this is ethically justifiable

Purpose of study: To describe the histological effects of botulinum toxin on gastrocnemius muscle affected by cerebral palsy. Method: Samples of gastrocnemius were obtained at the time of surgery. Ethical committee approval had been obtained for the study. Details of timing and doses of botulinum toxin previously administered to the muscle were recorded. A variety of immunohistochemical tests were employed to identify any changes in the muscle. Alterations in the distribution of myosin isoforms were identified with antibodies for fast, slow and neonatal myosin. The presence of persistent denervation was inferred from fibres deficient in neuronal nitric oxide synthase (nNOS). Mitochondrial abnormalities were assessed with an NADH stain and the presence of chronic atrophic fibres (nuclear clumps) noted. Results: Our first case had received 3 botulinum injections over a period of 5 years, the last one 3 years prior to biopsy. Histology showed pronounced abnormalities with a wide variation in fibre size, areas of myofibrillar disruption and 50% of fibres co-expressing fast and slow myosin. Other samples showed less change but showed more frequent nuclear clumps than controls, indicating chronic atrophy and more hybrid fibres than controls, but always less than 10%. Treated muscles also showed a small, variable number of atrophic fibres without nNOS. Treated samples showed no apparent fibre type grouping, a feature associated with collateral sprouting of peripheral nerves following denervation. Conclusions: Moderate doses of botulinum toxin appear to produce an alteration in muscle histology apparent several years afterwards. No correlation could be found between the timing of the previous injection or the dose of botulinum toxin injected and the severity of the changes. Botulinum toxin remains a valuable aid in the management of spastic muscle. However consideration should be given to other methods of treatment if an effective non surgical alternative exists

Orthopedic implants containing biodegradable magnesium have been used for fracture repair with considerable efficacy; however, the underlying mechanisms by which these implants improve fracture healing remain elusive. Here we show the formation of abundant new bone at peripheral cortical sites after intramedullary implantation of a pin containing ultrapure magnesium into the intact distal femur in rats. This response was accompanied by substantial increases of neuronal calcitonin gene-related polypeptide-a (CGRP) in both the peripheral cortex of the femur and the ipsilateral dorsal root ganglia (DRG). Surgical removal of the periosteum, capsaicin denervation of sensory nerves or knockdown in vivo of the CGRP-receptor-encoding genes Calcrl or Ramp1 substantially reversed the magnesium-induced osteogenesis that we observed in this model. Overexpression of these genes, however, enhanced magnesium-induced osteogenesis. We further found that an elevation of extracellular magnesium induces magnesium transporter 1 (MAGT1)-dependent and transient receptor potential cation channel, subfamily M, member 7 (TRPM7)-dependent magnesium entry, as well as an increase in intracellular adenosine triphosphate (ATP) and the accumulation of terminal synaptic vesicles in isolated rat DRG neurons. In isolated rat periosteum-derived stem cells, CGRP induces CALCRL- and RAMP1-dependent activation of cAMP-responsive element binding protein 1 (CREB1) and SP7 (also known as osterix), and thus enhances osteogenic differentiation of these stem cells. Furthermore, we have developed an innovative, magnesium-containing intramedullary nail that facilitates femur fracture repair in rats with ovariectomy-induced osteoporosis. Taken together, these findings reveal a previously undefined role of magnesium in promoting CGRP-mediated osteogenic differentiation, which suggests the therapeutic potential of this ion in orthopedics

Objectives: Posterolateral annular lesions were experimentally induced and allowed to mature for 12 weeks in the intervertebral discs of sheep. IDET was performed in an attempt to denervate and repair the annular lesion. The histological and immunohistochemical effects of IDET were studied. Summary of Background Data: IDET continues to be used as a minimally-invasive treatment for chronic discogenic low back pain, with success rates reported in up to 70% of cases. The mechanism of action by which IDET exerts its effect is poorly understood. Proposed mechanisms include the contraction of collagen and the coagulation of annular nociceptors. An ovine model was used firstly to induce a posterolateral annular lesion, secondly to assess the innervation of such a lesion, and thirdly to assess the effect of IDET on this innervation. Methods: Posterolateral annular incisions were made in 40 lumbar discs of 20 sheep. Twelve weeks were allowed for each annular lesion to mature. IDET was then performed in the disc with the posterolateral annular tear and in another control level. IDET was performed using a modified intradiscal catheter. Temperatures were recorded in the nucleus (T. N. ) and the posterior annulus (T. PA. ). The spines were harvested at predetermined intervals up to eighteen months. Histological sections of the discs were graded for disc morphology to assess degeneration and immunohistochemical staining to assess potential denervation. Results: Vascular granulation tissue consistent with a healing response was observed in the posterior annular tear of all incised discs from 12 weeks. PGP 9.5 positive nerve fibres were clearly identified in the adjacent periannular tissue and the outer few lamellae of the posterior annulus. During the IDET procedure the mean maximaximum T. PA. was 63.6°C and the mean maximaximum T. N. was 67.8°C. At sacrifice the number of nerve fibres identified in the posterior annular tear was the same for those specimens that had undergone IDET and those that had not. From six weeks after IDET there was evidence of thermal necrosis in the inner annulus and adjacent nucleus but sparing the periphery of the disc. Conclusions: IDET delivered at 90°C in the sheep consistently heated the posterior annulus and the nucleus to a temperature normally associated with coagulation of nociceptors and collagen contraction. IDET did not denervate the posterior annular lesion. Thermal necrosis was observed within the inner annulus and adjacent nucleus from six weeks after IDET. The reported benefits from IDET appear to be related to factors other than denervation and repair

Purpose: Lateral hypoaesthesia of the knee following peroperative section of an infrapatellar sensorial branch during anteromedial access for knee surgery is a well-known phenomenon. Development of a painful neurinoma at this level is much more exceptional but can be the cause of persistent pain, often becoming violent in the anteromedial region of the proximal tibia which may often evoke the diagnosis of mechanical failure of the prosthesis due to superficial conflict or loosening. There is relatively little in the French orthopaedic literature on this topic. We wanted to draw attention to this often missed diagnosis. Material and methods: We report the cases of three patients with degenerative knee disease who underwent total knee arthroplasty using a posterior stablised prosthesis implanted via an anteromedial approach. Persistent pain which developed over more than six months led these patients to consult. Several surgeons evoked a “classical” cause of postoperative pain resulting from postoperative loosening but the x-ray and scintigraphy findings were inconclusive. Physical examination demonstrated dysaesthesia in the lateral infra-pateller region with a positive Tinel sign on the anteromedial aspect of the knee immediately below the tibial implant suggestive of a neurinoma of the infrapatellar branch of the saphenous nerve. An anatomic study conducted on ten knees enabled us to identify the anatomic bases necessary to achieve local anaesthesic blocks providing the pretherapeutic diagnosis. The diagnostic tests were performed with injection of 5 ml xylocaine in the subcutaneous tissue over the medial aspect of the knee upstream from the suspected neurinoma. Complete resolution of pain evaluated 10 minutes after injection led to proposing neurotomy of the infra-patellar nerve via a separate medial incision. Results: Denervation provided immediate relief in three patients. For two, the pain and dysaesthesia regressed completely. Substantial improvement in hyperaesthesia was noted in one patient. Discussion: The anatomic studies demonstrated that one or more branches of the infra-patellar nerve cross the mid line from the apex of the patella to the anterior tibial tuberosity in 98% of the cases. In ongoing work during revision procedures for total knee arthroplasty, we have noted hypoaesthesia or anaesthesia in the infra-patellar nerve territory in 15% of the patients. Dell reported a series of 70 patients with postoperative neurinomas of the knee and obtained 86% good results after denervation. Conclusion: Hyperalgic iatrogenic neurinoma of an infra-patellar branch of the saphenous nerve is a certain but rare cause of pain after knee surgery, generally for prosthesis. Misdiagnosis of a mechanical complication is not uncommon. The clinically suggested diagnosis is easy to confirm by a subcutaneous local anaesthesia test. Neurotomy of the infra-patellar nerve can be proposed after failure of drug and physical treatments