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Biomedical subjects

Simon P Frostick

Publications and source records attributed to Simon P Frostick.

11 recordsLinked to original sources
PubMed2006

Clavicular hook plate for lateral end fractures:- a prospective study.

AIM: A prospective study was undertaken over a period of 4 years to evaluate the clinical and radiological outcomes following fixation with a clavicular hook plate for Neer types II and III fractures of lateral end clavicle. MATERIALS: Thirty-one patients (M:F; 24:7) with a mean age of 49 years (range 25-86 years) were recruited for the study. The mean follow-up duration was 40 months (range 18-68 months). Twenty-three patients were treated primarily and eight patients were treated for symptomatic delayed union. RESULTS: All the patients achieved clinical and radiological union over a mean of 12 weeks (range 6-18 weeks). Mean constant score at and after 3 months was 94 (range 82-100). Mean ASES score at and after 3 months was 26 out of a maximum of 30. CONCLUSION: The clinical result of fracture fixation of lateral end clavicle using hook plate appeared good in terms of fracture union and function. The principal advantages of this method were anatomical reduction of the fracture and early rehabilitation which lead to good shoulder girdle function.

Adult↗
PubMed2005

Fatal vascular outcomes following major orthopedic surgery.

Major orthopedic surgery is known to be associated with potentially serious arterial and venous vascular complications, although uncertainty exists about current event rates. Using electronic databases and investigator contact, we identified randomized and cohort studies reporting overall mortality and fatal vascular events. Where possible, studies reporting high autopsy rates (>60%) were examined. Pooled incidences were calculated from eligible studies. For Autopsy studies: Pooled overall mortality and fatal pulmonary embolism for patients undergoing elective hip and knee replacement without prophylaxis could not be calculated, while with prophylaxis they were 0.44% (95% confidence interval 0.02 to 0.87%) and 0.43% (0.01 to 0.85%). For patients undergoing hip fracture surgery, the corresponding rates without prophylaxis were 15.9% (14.5 to 17.3%) and 1.9% (1.4 to 2.4%). With prophylaxis, mortality and fatal pulmonary embolismrates were 8.5% (7.3 to 9.7%) and 1.0% (0.6 to 1.5%). Among Cohort studies: Pooled overall mortality and fatal pulmonary embolism for patients undergoing elective hip and knee replacement without prophylaxis were 0.93% (0.57 to 1.29%) and 0.36% (0.14 to 0.59%). For patients receiving prophylaxis (7 to 14 days), mortality and fatal pulmonary embolism were 0.57% (0.51 to 0.62%) and 0.18% (0.14 to 0.21%). Patients undergoing hip fracture surgery receiving prophylaxis hadmortality and fatal pulmonary embolismrates of 3.2% (2.8 to 3.6%) and 0.30% (0 to 0.61%). Vascular events contributed towards approximately 50% of all deaths with similar proportions due to ischemic heart disease, cardiac failure and pulmonary embolism. In conclusion, although prophylaxis results in a reduction in overall mortality and fatal pulmonary embolism, vascular events continue to be a common cause of mortality.

Autopsy↗
PubMed2005

Matrix metalloproteinase expression is related to angiogenesis and histologic grade in spindle cell soft tissue neoplasms of the extremities.

We defined the immunocytochemical expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in benign soft tissue neoplasms, fibromatoses, and sarcomas, together with the activity of gelatinase MMPs and TIMPs measured by zymography and reverse zymography in a subset of cases. The most strongly expressed MMP in all tumors was MMP-1, with weaker expression of MMP-10, MMP-11, and MMP-14 in most tumors. Nuclear expression of MMP-1, MMP-8, and MMP-13 was an unusual feature. TIMP-2 was expressed in all tumors, with stronger expression in fibromatoses than in sarcomas. Fibromatoses and high-grade sarcomas showed greater MMP-1 expression than other groups, and endothelial MMP-2 expression was more extensive in sarcomas. Differences in MMP and TIMP expression might be linked to the biologic behavior of soft tissue neoplasms. The activation of endothelial MMP-2 linked to widespread MMP-14 expression provides a mechanism for sarcomas to modulate their matrix and facilitate angiogenesis.

Adolescent↗
PubMed2004

Abnormal mitochondrial function and muscle wasting, but normal contractile efficiency, in haemodialysed patients studied non-invasively in vivo.

BACKGROUND: Muscle dysfunction, which contributes to morbidity in patients on haemodialysis, has several manifestations and a number of possible causes. We applied the non-invasive techniques of (31)P-magnetic resonance spectroscopy ((31)P-MRS), magnetic resonance imaging (MRI) and near-infrared spectroscopy (NIRS) to calf muscle of dialysed patients to define the abnormalities in muscle cross-sectional area (CSA), contractile efficiency, mitochondrial function and vascular O(2) supply. METHODS: We performed (31)P-MRS/NIRS/MRI studies on the lateral gastrocnemius during isometric plantarflexion and recovery in 23 male patients on haemodialysis (age 24-71 years; haemoglobin 9.9-14.2 g/dl; bicarbonate 17-30 mmol/l; urea reduction ratio 53-77%; parathyroid hormone 1-95 U/l) and 15 male controls (age 29-71 years). To understand the relationships between calf CSA and body mass we also performed MRI only in a further six male patients and 18 male controls. RESULTS: In patients, exercise duration was 30+/-11% lower than in controls. Muscle CSA was lower by 26+/-5%, but contractile efficiency (force/CSA/ATP turnover) was normal. Slowing of post-exercise phosphocreatine (PCr) recovery implied a 22+/-5% defect in effective 'mitochondrial capacity'. That PCr recovery was slow relative to NIRS recovery suggests that this is largely an intrinsic mitochondrial problem (not the result of impaired O(2) supply), one which, furthermore, correlated with CSA. Urea reduction ratio showed a negative correlation with body mass and CSA, but none with PCr rate constant. CONCLUSIONS: The relationships to urea reduction ratio reflect the effect of muscle mass on dialysis efficiency, rather than direct effects on muscle CSA or metabolism. The relationship between PCr recovery and calf CSA suggests a role for the mitochondrial defect, whatever its cause, in the development of muscle wasting, although a common cause (e.g. physical inactivity) for both abnormalities cannot be ruled out.

Humans↗
PubMed2004

Compression neuropathy of common peroneal nerve caused by an extraneural ganglion: a report of two cases.

Peroneal nerve entrapment is most common in the popliteal fossa, but is rarely caused by a ganglion. Although ganglionic cysts are very common lesions, they seldom cause serious complications. Ganglionic cysts developing in the sheath of a peripheral nerve or joint capsule may cause compression neuropathy. We report on two cases of compression neuropathy of the common peroneal nerve caused by an extraneural ganglion and its evaluation with magnetic resonance imaging (MRI) and ultrasonography. The differential diagnosis should involve L5 root pathology, a posttraumatic intraneural hemorrhage, a nerve compression near the tendinous arch located at the fibular insertion of the peroneal longus muscle, and a nerve-sheath tumor. The combination of MRI and ultrasonography is useful for the accurate diagnosis of this condition, and it should be treated by microsurgical exploration as soon as possible.

Adult↗
PubMed2004

Measuring myoelectric fatigue of the serratus anterior in healthy subjects and patients with long thoracic nerve palsy.

Proper function of serratus anterior plays a vital role in the movement and stability of the scapula, and thus of the glenohumeral joint and the upper limb. The unique anatomy of this muscle makes direct measurements of its fatigue properties impossible. Here we describe for the first time indirect measurements of the myoelectric manifestations of fatigue in the serratus anterior. Eight healthy volunteers (29-35 years) were tested, four of them on two different occasions, using two exercise protocols (60 s isometric maximum upward force in 120 degrees arm flexion, and 60 s maximum forward force at 90 degrees arm flexion) with simultaneous recording by surface and wire electrodes applied according to established methods. Signals were analysed to obtain the rate of fall of median EMG frequency and the rate of rise of amplitude. Both exercise protocols gave similar results. Frequency-slope measurements (mean rate of fall 0.6+/-0.1% initial value per second (% s(-1)) with both surface and wire electrodes) were more precise than those of amplitude (mean rate of rise 2.6+/-0.3% s(-1) with surface electrodes, only 1.3+/-0.2% s(-1) with wire electrodes). Surface electrodes gave much lower variation than fine wires, the coefficient of variation of slopes for surface electrodes being approximately 20-40% both between studies in a single subject and between subjects. In 5 patients (aged 22-59 years) recovering from long thoracic nerve palsy studied using surface electrodes the frequency slopes was normal (0.6+/-0.1% s(-1)), while the amplitude slope was reduced (0.9+/-0.4% s(-1), P = 0.01). This shows abnormal fatigue properties of the reinnervated muscle and a dissociation between the frequency and amplitude manifestations of fatigue.

Adult↗
PubMed2004

The role of cutaneous sensation in the motor function of the hand.

We studied the effect of abolishing cutaneous sensation (by infiltrating local anaesthetic around the median nerve at the wrist) on the ability of 10 healthy volunteers (a) to maintain a submaximal isometric pinch-grip force for 30 s without visual feedback, and (b) to perform a fine finger-manipulation 'handwriting' task. Blocking cutaneous sensation had no effect on ability to maintain pinch force, suggesting that muscle afferents have the major role in force-control feedback. However, a near-linear fall in force, present with or without block (mean slope=-1.3+/-0.2% s(-1)), which cannot be attributed to motor fatigue, reveals a shortcoming of the afferent feedback system. Blocking cutaneous sensation did impair ability to perform the more demanding writing task, as judged by an 18+/-6% increase in the length of the path between target points, a 22+/-9% increase in the duration of the movement and a 63+/-24% in 'normalised averaged rectified jerk', an averaged time-derivative of acceleration (all significantly nonzero, P < 0.04). These experiments demonstrate the relative importance of muscular and cutaneous afferent feedback on two aspects of hand performance, and provide a way to quantify the deficit resulting from the lack of cutaneous sensation.

Electromyography↗
PubMed2003

Arthroscopic capsular shrinkage of the shoulder for the treatment of patients with multidirectional instability: Minimum 2-year follow-up.

PURPOSE: The study goal was to evaluate the arthroscopic treatment of patients with multidirectional instability of the shoulder (MDI). MDI is a disabling condition as a result of pain and restriction of activity. The treatment of MDI is primarily nonsurgical (supervised physiotherapy). TYPE OF STUDY: Prospective cohort study. METHODS: Arthroscopic capsular shrinkage, using a bipolar radiofrequency system, was performed in 32 patients (33 shoulders). The mean age was 27 years (range, 15 to 49). The Constant score was used for assessment preoperatively and at 6-month intervals. In 8 patients, labral lesions were revealed at arthroscopy and were addressed using arthroscopic methods. RESULTS: The follow-up was from 24 to 33 months (26 mean). Patients without labral pathology (group A) and patients with labral lesions (group B) are discussed separately. Group A showed an increase in the mean Constant score at 6 months, but the scores reached a plateau after 6 months. Statistical analysis using 1-way analysis of variance (ANOVA) showed that the mean difference between the preoperative Constant score and the score at latest follow-up was statistically significant (P <.0001; 95% confidence interval, 13.4 to 31.6; standard error, 2.2). The rate of failure or complication was 16%. Three patients experienced recurrence of instability and another developed adhesive capsulitis. Overall, patient satisfaction was 83%. Group B showed an improvement in the Constant scores, and all 8 patients were satisfied. No clinical recurrence of the instability was seen in this group. However, 1 patient developed adhesive capsulitis. This group is too small to draw any statistically valid conclusions. CONCLUSIONS: The early results are encouraging. Postoperative physiotherapy is of paramount importance. Continued long-term follow-up of this relatively new technique is required to determine the failure rate increase that is likely to occur at longer time intervals.

Activities of Daily Living↗
PubMedDate not supplied

Shoulder electromyography in multidirectional instability.

We studied shoulder muscle activity in multidirectional instability (MDI) and multidirectional laxity (MDL) of the shoulder, our hypothesis being that altered muscle activity plays a role in their pathogenesis. Six muscles (supraspinatus, infraspinatus, subscapularis, anterior deltoid, middle deltoid, and posterior deltoid) were investigated by use of intramuscular dual fine-wire electrodes in 7 normal shoulders, 5 MDL shoulders, and 6 MDI shoulders. Each subject performed 5 types of exercise (rotation in neutral, 45 degrees of abduction, 90 degrees of abduction, flexion/extension, and abduction/adduction) on an isokinetic muscle dynamometer at two rates, 90 degrees /s and 180 degrees /s. After filtering, rectification, and smoothing, the electromyography signal was normalized by using the peak voltage of the movement cycle. In subjects with MDI, compared with normal subjects, activity patterns of the anterior deltoid were different during rotation in neutral and 90 degrees of abduction, whereas those of the middle and posterior deltoid were different during rotation in 90 degrees of abduction. In subjects with MDL, the posterior deltoid showed increased activity compared with normal subjects during adduction. Activity patterns of the supraspinatus, infraspinatus, and subscapularis appeared similar in both groups. Dual fine-wire electromyography offers insight into the complex role of shoulder girdle muscle function in normal movement and in instability. Altered patterns of shoulder girdle muscle activity and imbalances in muscle forces support the theory that impaired coordination of shoulder girdle muscle activity and inefficiency of the dynamic stabilizers of the glenohumeral joint are involved in the etiology of MDI. Interestingly, the abnormalities are in the deltoid rather than the muscles of the rotator cuff.

Adult↗