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

Purpose: The goal of laminectomy is to relieve spinal stenosis and improve radiculopathy. Back pain related to poor trunk muscular conditioning may negatively affect post-operative outcomes. A better understanding of this relationship is important to improve the selection of appropriate surgical candidates. The purpose of this study was to assess the association between cross-sectional lumbar paraspinal muscle area as measured by CT or MRI and outcomes following laminectomy. Method: Prospective observational study of 23 patients undergoing primary elective lumbar laminectomy without fusion who were assessed with pre-operative CT scans. Clinical outcomes were measured with Numerical Pain Scale (NPS) for back and leg pain and the Oswestry Low Back Disability Index (ODI) at baseline and follow-up at a minimum of one year. Lumbar paraspinal muscle cross-sectional area was measured using digital imaging software and adjusted for percent fat infiltration; CT scans evaluations were blinded to clinical outcomes. Results: There were significant improvements in clinical outcomes following laminectomy. ODI decreased from 53.9±11.8 (mean±standard deviation) at baseline to 27.3±20.6 after a follow-up of 15.2±3.5 months. A strong correlation existed between cross-sectional lumbar paraspinal muscle area after adjusting for infiltrating fat content an improvement in ODI (r=0.51, p< 0.02) or back pain NPS (r=0.55, p< 0.02). These relationships remained statistically significant after adjusting for age and body mass index. No significant associations were identified for improvements in leg pain NPS. Conclusion: This study suggests a possible relationship between cross-sectional lumbar paraspinal muscle area and outcomes following laminectomy. This raises important questions regarding the role of trunk muscular conditioning in the etiology of back pain and success of surgery. Further research is required to refine this measurement as a tool to improve patient selection for surgery

Background: Prospective population studies demonstrate that poor paraspinal muscle endurance increases the risk of developing first-time LBP and many CLBP studies also document excessive paraspinal muscle fatigability. The question arises as to whether this could have predisposed to chronic symptoms, through impaired spinal instability, especially in light of the wide inter-individual variation observed in the constitutionally determined paraspinal muscle fibre-type composition, which governs contractile performance. Objective: To determine whether CLBP-associated excessive paraspinal fatigue results from a paucity in the type I fibre content. Design: Control comparison using male subjects. Subjects: Thirty-five CLBP patients with Von-Korff Chronic Pain Scores of ≤ III (high level of residual function, despite pain, to negate effects of disuse atrophy), and 32 controls of similar age. Outcome measures: Fatigue-induced median frequency (MF) declines in the surface EMG signal, monitored bilaterally at L4 level during Biering-Sorensen- and 60%MVC- isometric fatigue tests. Percutaneous para-spinal muscle biopsies permitted histomorphometric comparisons. Results: Between-group differences were assessed using independent t-tests (p < 0.05). There were no differences for MF decline during the Biering-Sorensen -0.37(0.16) vs. -0.36(0.12), and the 60% MVC test −0.42(0.31) vs −0.51(0.29), and in the percentage number of type I fibres, 63.6% vs 64.3%, or percentage area occupied by type I fibres, 69.4% vs 67.2%, in the paraspinal muscles for patients and controls respectively (p> 0.05). Conclusion: Impaired CLBP-associated endurance is not the result of a constitutionally ‘adverse’ fibre-type composition

Aims: The purpose was to assess the effect of discec-tomy surgery on postural control, lumbar perception and reßex activation of paraspinal muscles during sudden upper limb loading. Methods: The study included 20 patients selected for an operation for chronic low back pain due to disc herniation and 15 controls without chronic back pain. The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The postural control was measured with a vertical force platform. Pain, disability and depression scores were recorded. Results: Patients had poorer lumbar perception (P=0.012) and postural control (P< 0.05) than healthy control subjects. The postural control remained unchanged but lumbar perception (P=0.054) and the lumbar feed-forward control (P=0.043) improved after the surgery. Conclusions: This study demonstrated impaired lumbar proprioception and postural control in sciatica patients. During short-term follow-up after operative treatment, postural control does not seem to change, but impaired lumbar proprioception and feed-forward control of paraspinal muscles seem to recover

Summary Statement. Paraspinal muscle contain higher proportion of slow-twich fibers. The fixation of the rat tail induced transition of muscle fiber types in the paravertebral muscles characterised by the decrease in the proportion of the slow type myosin heavy chain. Introduction. Lumbar degenerative kyphosis often accompanies back pain, easy fatigability, fatty degeneration and atrophy of back muscles. There are two types of skeletal muscle fibers according to oxidative activities: slow-twich (Type 1) and fast-twitch (Type 2) fibers. Type 2 fibers were subdivided into three types: Type 2A, 2B and 2D/X. Each fiber type primarily expresses a specific isoform of myosin heavy chain (MHC). It has been known that back muscles contain higher proportion of MHC type 1. However, the impact of kyphosis on the proportion of fiber types in the paravertebral muscles has not been fully understood. The aim of this study is to analyze the transition of muscle fiber types after kyophotic or straight fixation using a rat tail model. Methods. A rat tail was fixed in straight or kyphotic position (straight or kyphosis group) by a custom-made external fixator and wires. A group of animals which underwent only pierced wounds in their tails served as control. The gene expression profiles of isoforms of MHCs in dorsal coccygeal muscles were analyzed by quantitative RT-PCR. The fiber types of muscles were assessed using SDS-PAGE. Band densities of silver-stained gel were quantified. Results. At first, the gene expression profiles of MHCs and protein expression in the dorsal coccygeal muscles were compared with tibilis anterior and gastrocunemius muscles. Higher proportion of MHC type 1 gene and protein expression were confirmed in the dorsal coccygeal muscles than tibialis anterior and gastrocuneimus muscles. MHC type 2B protein expression was not detected in dorsal coccygeal muscles. Next, coccygeal muscles after straight or kyphotic fixation were analyzed and compared with control. Gene expression of MHC type 1 was decreased at 7 and 28 days after fixation in straight and kyphosis group. The significant difference was seen at 28 days in kyphosis group. The band densities of MHC protein type 1 and 2A plus 2D/X were decreased in both straight and kyophosis groups at 28 days after fixation while sample volume was adjusted by wet wight of dissected coccygeal muscles. The mean proportion of MHC protein type 1 separated by SDS-PAGE were decreased in straight and kyphosis group. The difference was significant in straight group. Discussion. Our results demonstrated that the fixation of the rat tail induced transition of muscle fiber types in the paravertebral muscles characterized by the decrease in the proportion of the MHC type 1. Back muscles are required to contract continuously to keep posture. Slow-twitch fibers in back muscle contribute for continuous contraction. Slow-twitch fibers utilise energy efficiently by oxidative process while fast-twitch fibers mainly consume glucose through glycolysis producing lactate acid. Not only decreased amount of MHC but also decreased proportion of MHC type 1 might be the reason of easy fatigability in lumbar degenerative kyphosis. The limitations of this study is the difference between human paravertebral and rat coccygeal muscles and short duration of observation

The August 2023 Spine Roundup360 looks at: Changes in paraspinal muscles correspond to the severity of degeneration in patients with lumbar stenosis; Steroid injections are not effective in the prevention of surgery for degenerative cervical myelopathy; A higher screw density is associated with fewer mechanical complications after surgery for adult spinal deformity; Methylprednisolone following minimally invasive lumbar decompression: a large prospective single-institution study; Occupancy rate of pedicle screw below 80% is a risk factor for upper instrumented vertebral fracture following adult spinal deformity surgery; Deterioration after surgery for degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research Network

The October 2024 Spine Roundup. 360. looks at: Analysis of risk factors for non-fusion of bone graft in anterior cervical discectomy and fusion: a clinical retrospective study; Does paraspinal muscle mass predict lumbar lordosis before and after decompression for degenerative spinal stenosis?; Return to work after surgery for lumbar disk herniation: a nationwide registry-based study; Can the six-minute walking test assess ambulatory function impairment in patients with cervical spondylotic myelopathy?; Complications after adult deformity surgery: losing more than sleep; Frailty limits how good we can get in adult spine deformity surgery

Summary Statement. Patients with adolescent idiopathic scoliosis show clear signs of abnormal motor coordination between the long superficial paraspinal muscles and the deep rotators. These findings suggest an abnormal behavior of the deep rotator muscles at the concave side. Introduction. An imbalance between the myoelectric activity of the muscles of the convexity and the concavity has been described in patients with adolescent idiopathic scoliosis (AIS). These findings are based on EMG patterns recorded with surface electrodes that do not distinguish between deep and superficial muscles. This work was aimed at analyzing the coupled behavior of the superficial and deep paraspinal muscles in subjects with AIS at both sides of the curve. Material. A total of 16 females (mean age, 16.2±4.3 years) with AIS between 20 and 35° Cobb (mean, 32.8±11.9°) underwent electromyography of the paraspinal muscles by direct intramuscular disposable concentric electrodes (Dantec DCN. TM. ) of 25mm and 37mm in length, and 0.46 mm. in diameter. A total of 4 electrodes were inserted at the apex on both sides of the curve (2 in deep rotator muscle and 2 in the long paraspinal superficial muscles). Myoelectrical activity was recorded simultaneously in the four muscle groups in different positions: standing, flexion, extension, right and left lateralizations, and rotations toward the side of the concavity and convexity. A 4-channel Keypoint® electromyography device (Medtronic, Denmark) was used. The recorded signals were analyzed in a laptop with Windows. ®. 7 Intel Core i3 64bit with Matlab. ®. R2012a. The following parameters were analyzed: Signal power, Mean and Median frecuency, and the Dimitrov spectral index, a marker of muscle fatigue. In addition, the signal power in each task was normalised by the signal power in standing position. The records were compared with those obtained in 4 healthy subjects, matched in age, without spinal deformity. Results. The signal amplitude in different subjects and tests ranged from tens of microvolts up to two milivolts. Most of the energy of the EMG signal was concentrated below 500 Hz in power spectrum density chart. In standing position, the activity of the deep muscle was greater than that of the long superficial paraspinal muscles, with higher activation in the convex side (63% of cases). Increased activity of the deep muscles as compared to the surperficial layers was also evident during flexion of the spine, with a higher activity of the deep muscles of the concavity. The 4 muscle groups showed low activity during spine extension movements, though the deep rotator activity was always greater than the superficial paraspinal muscles. In rotation exercises, the most active muscles were found the contralateral with a clear inhibition of the deep muscles of the concavity in the rotation to that side. This did not apply for rotation through the convex side. It was also noticeable that in the case of deep muscles, both sides of the spine require high activation when performing left flexion. Conclusions. Patients with AIS show clear signs of abnormal motor coordination between the superficial paraspinal muscles and the deep rotators. These findings do not clearly define whether this mismatch is primary or secondary to the presence of the deformity although they suggest an abnormal behavior of deep rotator muscles that could have etiopathogenic relevance

This work was aimed at study the role of paraspinal muscles on spinal tensegrity. Four different models of spinal tensegrity breakage with and without injury of the posterior spinal muscle were investigated. Fifteen minipigs (mean age 6-week) underwent costotransversectomy (CTT) at 5 consecutive vertebral segments. In 4 animals ribs and transverse processes (T7–T11) were removed through a posterior midline approach with complete desinsertion of paraspinal muscles. In other 3 animals, CTT was performed by a posterolateral approach (T6–T10) without detachment of paraspinal muscles. Other 4 minipigs underwent rib resection (T7-T11) throughout a thoracoscopic approach avoiding damage of posterior spinal muscles. A final group of 4 animals, a complete detachment of the paraspinal muscles was performed from T7 to T11 without removing bony structures and leaving in deep surgical wax attached to the spinous and transverse processes to avoid reinsertion of the muscles after surgery. Anatomic specimens were radiologically and macroscopically studied just at sacrifice 5 months after surgery. All 4 animals operated on of CTT by midline posterior approach developed structural spinal deformity with curve convexity at the side of rib removal (mean Cobb angle 34,6°). Animals undergoing CTT by posterolateral approach without paraspinal muscle detachment did not develop any significant spinal deformity. Absence of spinal deformity was also found in those animals in which rib resection was performed by thoracoscopy without injury of the posterior spinal muscles. All 4 animals undergoing detachment of the paraspinal muscles without CTT and application of the surgical wax developed scoliotic curves (mean Cobb angle of 28°). In conclusion, a new insight on the underlying pathogenic mechanisms of scoliotic curves is given by using this spinal tensegrity model. Isolated damage of the posterior muscle-ligamentous structures around the costotransverse joints breaking muscles spine tensegrity seems to be mandatory to induce scoliotic deformity. Rib removal alone appeared to have less scoliotic inductive implication. The finding questions previous knowledge on scoliosis etiopathogeny

Paraspinal muscle dysfunction is associated with chronic low back pain (CLBP) in prospective studies, some authors suggesting a primary role for muscle in CLBP development. To investigate this possibility, we compared paraspinal muscle electromyographic (EMG) fatigue characteristics with fibre-type composition in ambulant, male CLBP patients and male controls of similar age. Thirty-five patients with Chronic Pain Grades of III (a high level of residual function, despite pain, negated the effects of disuse atrophy), and 32 controls were studied. Paraspinal surface EMG signals were recorded from the T10/11 and L4/5 regions bilaterally during standard isometric endurance tests. The rate of fatigue-induced median frequency (MF) decline was calculated from the power spectrum. Percutaneous paraspinal muscle biopsies permitted the determination of muscle fibre-type characteristics. MF decline, mean fibre size and relative area occupied by fibre types did not differ significantly between groups. The paraspinal muscles of ambulant CLBP patients demonstrate no excessive fatigability, when assessed by EMG, nor a relative paucity in the area occupied by either fibre type. Patients developing CLBP do not demonstrate an adverse paraspinal muscle fibre-type composition

Aims. To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod. Methods. This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining. Results. Titanium (Ti), vanadium (V), and neodymium (Nd) concentrations in the biopsies taken near the wear marks were found to be significantly higher than those in the control tissue samples. Significantly increased Nd concentrations were also found in the tissues near the barrel of the MCGR. Chronic inflammation was revealed by the histological studies with fibrosis and macrophage infiltration. Black particles were present within the macrophages in the fibrotic tissues. Conclusion. Ti and V were generated mainly at the BO due to metal-on-metal contact, whereas the Nd from the rotor of the MCGR is likely released from the BO during distraction sessions. Phagocytotic immune cells with black particles inside raise concern regarding the long-term implications of metallosis. Cite this article: Bone Joint J 2020;102-B(10):1375–1383

Segmental spinal reflexes (stretch reflexes) were studied in patients with scoliosis. The proprioceptive responses to the phasic stretch of the paraspinal muscles were asymmetric in all patients, and were increased on the convex side. The asymmetry was more pronounced when the patients were standing. The observed asymmetry of the reflex responses was taken to indicate asymmetry in the tone and postural activity of the superficial layer of the paraspinal muscles. A reciprocal relationship was found in the segmental reflex organisation between the superficial and deep layers of the paraspinal muscles. The increase in reflex response of the superficial muscles on the convex side can be due to diminished reciprocal inhibition from weak, deep muscles. Thus a segmental neurogenic disorder involving predominantly the deep paraspinal muscles of the convexity of the curve may be the primary lesion responsible for the development of scoliosis

Purpose. Cognitive Muscular Therapy (CMT) is a new treatment for low back pain which integrates psychological techniques for pain management alongside training to improve postural control. Rather than focus on postural alignment or strength, CMT aims to improve the regulation of postural tone (low-level activity which supports the body against gravity). This is achieved by teaching patients an awareness of compensatory paraspinal activation, which can be triggered by overactivity of the abdominal muscles. The aim of this study was to understand whether CMT could reduce symptoms associated with low back pain and improve paraspinal muscle activation. Methods and results. Fifteen patients with chronic low back pain received seven weekly sessions of CMT from a physiotherapist. Clinical data was captured at baseline and two weeks after the intervention using the Roland-Morris questionnaire and the pain catastrophising scale. Activation of the erector spinae muscle during walking was also measured at baseline and after the final intervention session. Change data were analysed using paired t-tests. There was a 75% reduction (p<0.001) in the Roland-Morris score from a mean (SD) of 9.3(2.9) to 2.3(2.6), along with a 78% reduction in pain catastrophising (p<0.002) from 16.6(13) to 3.7(4.8). Activation of the contralateral erector spinae muscles reduced by 30% (p<0.01) during the contralateral swing phase of walking. Conclusion. In this small sample, CMT delivered large clinical improvements and reduced activation of the low back muscles during walking. Larger randomised trials are now required to confirm whether CMT could outperform existing physiotherapy treatments for chronic back pain. Conflict of interest. No conflicts of interest. Source of funding. University of Salford

The posterior midline approach used in spinal surgery has been associated with a significant rate of wound dehiscence. This study investigates anatomical study of the arterial supply of the cervical and thoracic spinal muscles and overlying skin at each vertebral level. It aimed to provide possible anatomical basis for such wound complications. A dissection and angiographic study was undertaken on 8 cadaveric neck and posterior torso from 6 embalmed and 2 fresh human cadavers. Harvested cadavers were warmed and hydrogen peroxide was injected into the major arteries. Lead oxide contrast mixture was injected in stepwise manner into the subclavian and posterior intercostal arteries of each specimen. Specimens were subsequently cross-sectioned at each vertebral level and bones elevated from the soft tissue. Radiographs were taken at each stage of this process and analysed. The cervical paraspinal muscles were supplied by the deep cervical arteries, transverse cervical arteries and vertebral arteries. The thoracic paraspinal muscles were supplied by the superior intercostal arteries, transverse cervical arteries and posterior intercostal arteries. In the thoracic region, two small vessels provide the longitudinal connection between the segmental arteries and in the cervical region, deep cervical arteries provide such connection from C3 to C6. The arterial vessels supplying the paraspinal muscles on the left and right side anastomose with each other, posterior to the spinous processes in all vertebral levels. At cervical vertebral levels, source arteries travel near the surgical field and are not routinely cauterised; Haematoma is postulated to be the cause of wound complications. At thoracic levels, source arteries travel in the surgical field and tissue ischemia is a contributing factor to wound complications, especially in operations over extensive levels. Post-operative wound complications is a multi-factorial clinical problem, the anatomical findings in this study provide possible explanations for wound dehiscence in the posterior midline approach. It is postulated that drain tubes may reduce the incidence of haematoma in the cervical level

Introduction: Acute compartment syndrome is most commonly seen in the lower limb. Only four cases have been reported in the paraspinal muscles. The common features of this condition have not been described. Methods: Following the successful surgical treatment of a case of bilateral paraspinal muscle compartment syndrome, a thorough search was made of all similar cases in Medline, and by hand-searching of references lists. Results: Only four other cases of non-traumatic paraspinal compartment syndrome were identified in the literature. Closer analysis revealed many features in common with our case. The condition tends to occur in skiers in their 20s with a previous history of exercise-induced back pain. Patients present with paraspinal muscle spasm and loss of sensation of the loin, after a few days of heavy exertion. There is abdominal tenderness and bowel sounds are reduced. Consistent findings on blood chemistry are marked elevation of creatinine kinase, myoglobin and LDH. There is an associated myoglobinuria. MRI is helpful in identifying extent of muscle involvement and guiding surgical intervention. The most useful investigation is the direct measurement of compartment pressures. Treatment can be operative or non-operative, although surgery is associated with more rapid recovery and elimination of pain. Discussion and Conclusion: The common features of acute paraspinal compartment syndrome of non-traumatic origin have not previously been recognised. We have helped define the characteristics of this condition to aid earlier recognition and treatment

Purpose & Background: The spinal muscles are increasingly being linked to spinal complaints. However, little is known regarding the corticospinal control of these muscles. Corticospinal pathways can be activated using transcranial magnetic stimulation (TMS) applied over the motor cortex. This study uses TMS to assess corticospinal input to the paraspinal muscles in the thoracic region. Methods: Ten individuals (mean [± SD] age 33 ± 10 yrs; mean height 166 ± 10 cm; two left-handed; five male, five female) with no history of neurological disorder were recruited into this study and written informed consent obtained. Subjects lay prone in a relaxed position with the head unsupported. Surface electromyographic (EMG) recording electrodes were positioned bilaterally over the paraspinal muscles adjacent to thoracic spinal processes T1 and T2. TMS was applied using a MagStim 200 stimulator connected to a double cone coil with its cross-over positioned over the vertex so that the maximum induced current flowed in a posterior to anterior direction. The stimulus intensity was adjusted in steps of 5% of the maximum stimulator output (MSO), and ten stimuli were delivered at each strength. Threshold for a motor evoked potential (MEP) in each muscle was determined as the minimum intensity that would evoke MEPs to 50% of stimulus presentations. Latency of MEPs was determined by measuring the time between the stimulus and the start of the first deflection in the MEP. The procedure was repeated for the other pairs of thoracic segments between T3 and T12. Results: In all subjects, it was possible to evoke MEPs in relaxed paraspinal muscles at all thoracic levels. Mean (±SEM) threshold for evoking a MEP on the left side increased from 47 ± 2.5 %MSO at level T1 to 55 ± 2.5 %MSO at T12 (Pearson correlation, P< 0.05) but remained more constant (P> 0.05) on the right side (T1, 55 ± 3.9 %MSO; T12, 57 ± 3.3 %MSO). Over all levels tested, mean threshold for MEPs was 3.9 ± 0.6 %MSO higher on the right than the left side (Student’s paired t-test, P< 0.05). Mean latency of MEPs on the left increased from 11.9 ± 0.7 ms at level T1 to 15.5 ± 0.6 ms at T12 and on the right from 12.3 ± 0.5 ms at level T1 to 16 ± 0.7 ms at T12 (Pearson correlation, P< 0.05). Throughout the thoracic region, latency of MEPs was 0.8 ± 0.2 ms longer on the right than the left side (Student’s paired t-test, P< 0.05). Conclusion: The latency of MEPs increased as recordings were made from muscles innervated more caudally. Threshold for MEPs varied between subjects and at different spinal levels but our results indicate that it was higher at more caudal levels, perhaps suggesting weaker corticospinal innervation. Threshold was lower and latency shorter for muscles on the left side raising the interesting possibility that paraspinal muscles have some asymmetry in their corticospinal innervation. This study has provided us with baseline electrophysiological data allowing us to investigate the voluntary control pathways to muscles stabilising the thoracic spinal cord following trauma or disease

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Aims. The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results. Methods. Consecutive AIS patients treated with an MIS technique at two tertiary centres from June 2013 to March 2016 were retrospectively included. Preoperative patient deformity characteristics, perioperative parameters, power of deformity correction, and complications were studied. A total of 93 patients were included. The outcome of the first 25 patients and the latter 68 were compared as part of our safety analysis to examine the effect of the learning curve. Results. In the first 25 cases, with a mean follow-up of 5.6 years (standard deviation (SD) 0.4), the mean preoperative major Cobb angle was 57.6° (SD 9.8°) and significantly corrected to mean 15.4° (SD 5.6°, 73% curve correction). The mean preoperative T5-T12 was 26.2 (SD 12.8) and significantly increased to mean 32.9 (SD 8.3). Both frontal and sagittal plane correction was conserved two years after surgery. The rate of perioperative complications was 12% and three further complications occurred (three deep delayed infection). In the latter cases, 68 patients were included with a mean follow-up time of three years (SD 0.6). The mean preoperative major Cobb angle was 58.4° (SD 9.2°) and significantly corrected to mean 20.4° (SD 7.3°).The mean preoperative T5-T12 kyphosis was 26.6° (SD 12.8°) and was significantly increased to mean 31.4° (SD 8.3°). Both frontal and sagittal correction was conserved two years after surgery. The perioperative (30 day) complication rate was 1.4%. Two (2.9%) additional complications occurred in two patients. Conclusion. MIS for AIS is associated with a significant correction of spine deformity in the frontal and sagittal planes, together with low estimated blood loss and short length of stay. The perioperative complication rate seems to be lower compared with the standard open technique based on the literature data. The longer-term safety of MIS for AIS needs to be documented with a larger cohort and compared with the standard posterior approach. Cite this article: Bone Joint J 2020;102-B(4):506–512

The requirements for a motion segment fusion for degenerative disc disease are relief from symptoms from a solid union with minimal damage to surrounding tissue. This is possible with the ‘Mini PLIF’ using the B Twin cages and facet screws. This procedure produces reliable relief of symptoms with a solid fusion. The use of facet screws mean that the nerve supply of the paraspinal muscles is protected. Between June 2002 and February 2006 35 patients underwent this procedure. There were 13 males and 22 females with an average age of 40 years from all walks of life. 30 patients had back and leg pain with only 5 having solely back pain. 28 patients had surgery at L5/ S1 with 4 patients at L4/5 and 3 at both. The median pre operation ODI was 53 (IQR 60–44) and at one year follow up the ODI was 24 (IQR 37–13). There were two complications of superficial infection and two pseudarthroses requiring pedicle screw constructs and revision bone grafting to achieve union. We believe this procedure demonstrates good relief from symptoms with a good fusion rate preserving the paraspinal muscles

Purpose. Lumbar paraspinal muscle dysfunction and low back pain are strongly correlated. Muscle atrophy is common in LBP and is recognised by MRI scan. Corticosteroid injections and physical rehabilitation programs are advocated for treatment of LBP. The purpose is to evaluate efficacy of specific lumbar multifidus muscle retraining exercises and perifacet multifidus injections in treatment of Low Back Pain (LBP) and referred leg pain. Method. 63 patients with non-specific LBP, with or without leg pain, were randomised to three treatment groups. MR images of paraspinal muscle and the atrophy classified. A-Control group, standard physiotherapy for 10 weeks. B-Multifidus rehabilitation program for 10 weeks. C-Perifacet injection (multifidus injection) with methylprednisolone. ODI was primary outcome measure and the SF-36, modified Zung Depression Index and others were secondary outcome measures. Results. 56 patients completed trial. ODI improved from a mean of 29.9 to 25.9, but there were no statistically significant differences between groups. 62% of patients were at risk/had major psychological overlay. LBP improved most in group C (Perifacet injection) (P< 0.02), mean improvement in SF-36 bodily pain score was 21.2 (with a 95% CI of 2.1-44.0) while PF and SF were improved most in group B (multifidus rehabilitation) (P< 0.03). Conclusion. Perifacet injection and a multifidus retraining program are more effective than standard physiotherapy in relieving pain and improving physical capacity respectively. Multifidus rehabilitation program is the recommended treatment for non-specific LBP, as the ultimate goal should be to restore function. Perhaps the combination of perifacet injection to relieve pain followed by multifidus retraining program is the best treatment option. No change in the multifidus muscle was seen over time