Probing the Shape of the Weyl Fermi Surface of NbP Using Transverse Electron Focusing.

Weyl semimetals are defined by their unique Fermi surface, comprising pairs of Weyl points of opposite chirality, connected through topological surface states. Angle-resolved photoemission spectroscopy (ARPES) has been used to verify the existence of the Weyl points and the Fermi arcs. However, ARPES is limited in resolution, leading to significant uncertainty when characterizing the shape of the Fermi surface of semimetals and measuring features such as the distance between the Weyl points. Here, to surpass the resolution of ARPES, we combine quantum oscillation measurements with transverse electron focusing experiments. These techniques offer complementary information, enabling the reconstruction of the distinctive peanut-shaped cross section of the Weyl Fermi surface and accurately determining the separation between Weyl points in the Weyl semimetal NbP. Our Letter showcases the integration of quantum oscillations and transverse electron focusing, allowing for the measurements of complex Fermi surface geometries, concurrently with carriers' transport properties, in high-mobility quantum materials.

Chronic exertional compartment syndrome: correlation of compartment pressure and muscle ischemia utilizing 31P-NMR spectroscopy.

In the past 5 years, a great deal of time and effort has been expended in an effort to better define clinical, anatomic, and laboratory parameters of CECS. It is now a well-recognized entity and one that can be readily resolved with fasciotomy. But the reasons for predisposition and the pathophysiologic mechanisms remain obscure. It appears, however, that basing the decisions for fasciotomy on clinical characteristics alone leads to overdiagnosis and excessive surgery. In this series, almost 50% of the referred subjects failed to demonstrate adequate laboratory criterion for the diagnosis of CECS. Fasciotomy in these patients may have effected a cure, but the reasons may be unrelated to increased intracompartmental pressure. Furthermore, in the laboratory diagnosis of CECS, the rate of return to resting compartment pressure following exercise seems more accurate than reliance on resting pressure alone. 31P-NMR has proved valuable in the dynamic assessment of muscle ischemia as reflected by relative PCr concentrations. Finally, although a mechanism explaining the source of pain has not been established by this study, it appears that ischemia is not a significant factor.

Repair of Achilles tendon ruptures with a polylactic acid implant: assessment with MR imaging.

An investigational tendon repair device composed of a polymer of lactic acid (PLA) is currently undergoing multicenter clinical trials for use in repairing rupture of the Achilles tendon. The advantages of the PLA device include high tensile strength and the induction of a rapid proliferative tissue response resulting in a shorter rehabilitation period than with conventional surgical repair. We reviewed 16 MR examinations performed in 10 patients 3-35 months after repair to characterize the MR appearance. All 16 T1-weighted sagittal images revealed a thickened fusiform tendon with streaks of moderate signal within the tendon corresponding to the PLA device and its surrounding collagenogenic response. The double-echo T2-weighted axial images at the mid tendon level demonstrated progressive changes in the signal pattern of the central portion of the tendon that reflected the maturation of the healing tendon. All tendons repaired with PLA implants were uniformly hypertrophied relative to the contralateral normal side because of the induced proliferative collagenogenic ingrowth. Two follow-up MR examinations were performed in six patients and showed mean reductions in tendon caliber of 24% and 30% at the mid and inferior levels. MR imaging of the Achilles tendon repaired with PLA implants shows a diffusely thickened tendon with streaks of signal within the tendon that distinguish it from tendons repaired by conventional techniques.

Abdominal and groin injuries in tennis.

Although abdominal and groin injuries are not unique to the game of tennis, the very mechanics of the ground stroke and overhead volley predispose participants in this sport to the chronic pain and frustration of these injuries. Careful consideration must be given not only to the muscular anatomy of the region but also to the visceral and neurologic anatomy. A patient, controlled program of rehabilitation, emphasizing flexibility and subsequent strengthening, must be stressed if recurrence is to be avoided.

Management and rehabilitation of ligamentous injuries to the ankle.

The management of ligamentous injuries to the ankle is controversial. Neither the methods for classification and diagnosis, or the procedures for treatment are clear cut. Ankle sprains are a common occurrence, with the majority involving the lateral ligament complex. Within this complex, the anterior talofibular ligament is injured most frequently, usually while the foot is in the plantar flexed position. Ankle injuries can be diagnosed through physical exam, including the anterior drawer test and/or a stress exam, or through roentgenographic evaluation. The purpose of the stress roentgenogram is to measure the degree of talar tilt. However, it does not always yield consistent, reliable results. This inconsistency has led to the use of arthrography. There is debate over its use as well, however, Ankle sprains can be classified into three groups, according to functional loss. Treatment for first and second degree sprains is usually non-operative. The best approach to Grade III sprains is debatable. The issues in the treatment of Grade III sprains are first, whether treatment should be operative or non-operative, and second, whether non-operative treatment should emphasise immobilisation or mobilisation. Brostrom's work is cited as noteworthy. He recommended adhesive strapping followed by mobilisation as the treatment of choice, and reserves surgery for cases of chronic instability. Results demonstrated that strapping yielded shorter disability periods, while surgery produced less instability. The prevention of functional instability is a major concern in the treatment of ankle injuries. There is no consensus for treating a lateral ligament rupture. The authors suggest immobilisation followed by a rehabilitative programme. Three methods of immobilisation are plaster casting, adhesive strapping, and the air-stirrup. The physiological mechanism of cryotherapy and thermotherapy are discussed briefly and recommendations for their use are provided. Aspiration is also discussed. Loss of motion is designated as a primary cause of chronic pain and reinjury, and exercises intended to restore range of motion are provided. Exercises aimed at restoring strength and proprioception are also presented. This allows for return to activity and serves to prevent reinjury.

A modified Bristow-Helfet-May procedure for recurrent dislocation and subluxation of the shoulder. Report of two hundred and twelve cases.

A modified Bristow-Helfet-May procedure was performed for recurrent dislocation or subluxation of the glenohumeral joint in 207 patients (212 shoulders), whose average age at the time of surgery was 20.3 years (range, fourteen to forty-seven years). The procedure was modified by directing the coracoid segment and conjoined tendon over the superior border rather than through the substance of the subscapularis tendon and muscle. The indications were either documented recurrent anterior dislocation of the glenohumeral joint or subluxation with instability as demonstrated on examination with the patient under anesthesia. The procedure was evaluated on the basis of the rate of recurrence of dislocation and subluxation, postoperative complications, the patients' subjective evaluation, and the effect of the procedure on the motion of the glenohumeral joint and the strength of the muscles of the shoulder as related to overhead throwing. Eight (3.8 per cent) of the shoulders redislocated and ten (4.7 per cent) had one or more subjective episodes of subluxation after the procedure. Complications included postoperative infection in two patients and problems with the screw that required its removal in ten. One hundred and thirty-one (62 per cent) of the patients responded to a questionnaire regarding their subjective evaluation of the results of surgery. Eleven (8 per cent) were unable to perform daily activities that involved overhead work, and forty-five (34 per cent) stated that they still had some degree of discomfort or pain in the shoulder. One hundred and twenty-six patients (96.2 per cent) stated that they were happy with the results of the surgery and would have the procedure again. Thirty patients had Cybex testing of the muscles of the shoulder. Only three (16 per cent) of the nineteen athletes whose dominant arm had been operated on returned to their pre-injury level of throwing. Data obtained with regard to changes in the range of motion and strength of the glenohumeral joint indicate that this loss of throwing ability was not due solely to a loss of glenohumeral motion. It appeared to be also related to a concomitant loss of strength at the extreme of external rotation of the humerus and the initiation of internal rotation of the humerus.

Osteoid osteoma. Distant, periarticular, and subarticular lesions as a cause of knee pain.

Osteoid osteoma, a benign osteoblastic tumour comprised of osteoid and atypical bone, is a well-known entity. However, clinical diagnosis may be delayed, especially when the pain is referred to a nearby joint. This paper reports a series of 11 cases occurring in physically active patients in whom the diagnosis was delayed because of pain referral to the knee. The mean duration from the onset of symptoms to diagnosis of osteoid osteoma was 20 months (range 3 to 48 months). Review of these 11 lesions indicates that they can be classified on the basis of their anatomical location: (a) distant to the knee; (b) periarticular; or (c) subarticular (intraarticular). It should be noted that initially only 5 of the 11 cases displayed characteristic x-ray findings; in the remaining 6 cases, diagnosis was dependent on positive 99mTc radionuclide bone scans, tomograms, and computerised tomography scans. Of the 9 patients who underwent surgical resection of their lesions, all had complete relief of symptoms and all continued to be asymptomatic at follow-up evaluations.

Application of electrothermal energy in arthroscopy.

Bovine stifle joints were utilized for the application of electrothermal energy in arthroscopic surgical procedures. The anatomy of the bovine stifle joint was comparable to that of the human knee and proved to be a suitable model for arthroscopic surgery. Partial and total meniscectomies were performed in vitro and in situ on cadaveric stifle joints using 1.5% glycine as a liquid medium. Histologic preparations revealed no adverse effects associated with the use of glycine, and coagulation necrosis never extended more than 0.1 mm into the meniscal substance. Instrumentation designed specifically for the intraarticular application of electrothermal energy facilitated arthroscopic meniscectomy with minimal effect on adjacent tissue.

Fractures of the base of the fifth metatarsal distal to the tuberosity. Classification and guidelines for non-surgical and surgical management.

Between 1973 and 1982 forty-six fractures of the base of the fifth metatarsal, distal to the tuberosity, were treated and followed for a mean of forty months (range, six to 108 months). Roentgenographic criteria were used to define three types of fractures: acute fractures characterized by a narrow fracture line and absence of intramedullary sclerosis; those with delayed union, with widening of the fracture line and evidence of intramedullary sclerosis; and those with non-union and complete obliteration of the medullary canal by sclerotic bone. Of the twenty-five acute fractures in this series, fifteen were treated with a non-weight-bearing toe-to-knee cast, and fourteen of them healed in a mean of seven weeks. Only four of the other ten, which were treated with various weight-bearing methods, progressed to union. Of the twelve patients with delayed union, one refused treatment, one was treated with a bone graft, and ten were treated initially by immobilization of the limb in a plaster cast and weight-bearing. Of these ten fractures, seven healed in a mean of 15.1 months and three eventually required grafting for non-union. Of the nine non-unions in the series, which were treated primarily with medullary curettage and bone-grafting, eight healed in a mean of three months. In all, twenty fractures were treated surgically with an autogenous corticocancellous graft that was inlaid after thorough curettage and drilling of the sclerotic bone that obliterated the intramedullary cavity. Of these twenty fractures, nineteen progressed to complete healing and one, to asymptomatic non-union.(ABSTRACT TRUNCATED AT 250 WORDS)

Coracoid fracture as a complication of surgical treatment by coracoclavicular tape fixation. A case report.

In a 22-year-old man surgically treated for acromioclavicular dislocation, coracoid fracture was caused by bone failure at the Mersaline loop. The addition of bony erosion between the two drill holes in the clavicle caused the tape to loosen and the deformity to recur. Postoperative infection may also have played a role in causing the coracoid fracture. When tape is used, it should be passed around the clavicle, not through it. If the deformity recurs, coracoid fracture should be suspected.