Quantum critical dynamics in a 5,000-qubit programmable spin glass.

Experiments on disordered alloys1-3 suggest that spin glasses can be brought into low-energy states faster by annealing quantum fluctuations than by conventional thermal annealing. Owing to the importance of spin glasses as a paradigmatic computational testbed, reproducing this phenomenon in a programmable system has remained a central challenge in quantum optimization4-13. Here we achieve this goal by realizing quantum-critical spin-glass dynamics on thousands of qubits with a superconducting quantum annealer. We first demonstrate quantitative agreement between quantum annealing and time evolution of the Schrödinger equation in small spin glasses. We then measure dynamics in three-dimensional spin glasses on thousands of qubits, for which classical simulation of many-body quantum dynamics is intractable. We extract critical exponents that clearly distinguish quantum annealing from the slower stochastic dynamics of analogous Monte Carlo algorithms, providing both theoretical and experimental support for large-scale quantum simulation and a scaling advantage in energy optimization.

Cervical nerve root variant: report of two cases under the cervical endoscopy and review of clinical literature.

BACKGROUND: We know of five cases of cervical nerve root variants that have been reported, all of which were found during posterior cervical surgery. We reported two cases of cervical nerve root variants. One had two anomalous branches of the C7 root, is the other had a C5, C6 nerve root communication branch. CASE DESCRIPTION: A 62-year-old female presented with neck and right upper extremity pain, accompanied by hypaesthesia in her right forearm for 4 months. Preoperative X-ray film, magnetic resonance imaging (MRI) and computed tomography (CT) scan demonstrated C6-7 uncovertebral joint hyperplasia and foraminal stenosis. She underwent posterior cervical endoscopic foraminoplasty. The right C7 nerve root was observed to have two anomalous branches originated from a proximal trunk. After the surgery, the symptoms resolved. A 54-year-old female presented with radiating pain and numbness in her right arm and hand for 4 months. Preoperative MRI showed a C5/6 intervertebral disc herniation. She had hypaesthesia in radial side of her right arm and 1st-3rd fingers. Posterior cervical endoscopic foraminalplasty was performed for the patient. After decompression of the bony wall of the posterior nerve root canal, a 2-mm thick communicating nerve was observed emerging from the dura with the C6 nerve root and exiting to the caudal level. After the surgery, the symptoms resolved immediately. CONCLUSIONS: Cervical nerve root variant may be more apparent on edoscopic approaches to the cervical foraminae than at open surgery.

The effect of range of motion after single-level discover cervical artificial disk replacement.

STUDY DESIGN: A biomechanical study of cervical artificial disk replacement (CADR). OBJECTIVE: This study aimed to investigate the range of motion (ROM) of the treated segment, the ROM of the adjacent segments, the global ROM in the sagittal plane, and the total neck ROM in the 3 cardinal planes after single-level Discover CADR. SUMMARY OF BACKGROUND DATA: CADR could theoretically preserve the motion function of the treated segment without affecting the adjacent segments significantly. Although previous studies have reported excellent clinical outcomes and ROM of the treated segment after CADR, few studies have focused on the ROM of the adjacent segments, the global ROM, and the total neck motion. METHODS: C5/6 Discover CADR was performed in 58 patients (37 male and 21 female) between September 2008 and September 2010. Anteroposterior, lateral, and flexion-extension lateral radiographies were performed before operation and at the 1-year follow-up. Clinical parameters, including the Japanese orthopedic association score, the neck disability index, and the visual analogue scale, were evaluated. The ROM of the treated segment (C5/6) and the adjacent segments (C4/5 and C6/7) and the global ROM (C2/7) were measured by radiography. To evaluate the total neck ROM, the cervical ROM device was advocated. Preoperative and postoperative data were compared using the paired t test. RESULTS: The Japanese orthopedic association score was 14.3 at the 1-year follow-up as compared with the preoperative score of 8.7. Other scoring systems had improved postoperatively, including the neck disability index from 85.1 to 68.6 and the visual analogue scale from 7.8 to 3.3. Compared with the preoperative ROM, the postoperative ROM increased by 3.0 degrees (27.0%) in C5/6, 1.3 degrees (13.7%) in C4/5, and 1.8 degrees (17.6%) in C6/7. The postoperative global ROM also increased by 6.7 degrees (15.2%) compared with preoperative global data. Compared with the preoperative total neck motion, the postoperative total neck motion increased by 8.3 degrees (9.3%) in the sagittal plane and 6.1 degrees (7.7%) in the coronal plane. There was an insignificant increase of 0.8 degrees (0.6%) in the horizontal plane. CONCLUSIONS: This study demonstrated that the single-level Discover CADR increased the ROM of the treated segment and the adjacent segments. There was also an increase in the global ROM and the total neck motion in the sagittal and the coronal planes, although there was no significant difference in the horizontal plane before and after operation.

The use of intra-articular vancomycin is safe in primary hip and knee arthroplasty.

Background: The use of a single dose of intra-articular antibiotic (IAA) has been reported in reducing the rate of prosthetic joint injection after total hip and knee arthroplasty. We examine the safety of IAA in primary hip and knee replacement surgery and the blood levels and joint fluid levels of vancomycin utilising this technique. Methods: From August to October 2021, 68 patients undergoing primary total joint arthroplasty (THA & TKA) were given 1g vancomycin intra-articularly (IA)after closure of the fascia. All patients received 2g cefazolin intravenously (IV) 30 min prior to the procedure as is our standard prophylaxis, and 21 of the patients (IA + IV) were also administered an additional 1 gm vancomycin IV. Post-operative blood vancomycin, creatinine land eGFR level monitoring was performed d1 and d3. To determine the post-operative intra-articular vancomycin levels, surgical drain fluid was sampled at day 1 and 2, in 10 patients. Results: All patients had serum vancomycin levels measured on day 1 and 3. In the group where vancomycin was injected after fascial closure, the average blood vancomycin level day 1 was 5.2 µg/ml (range 2.0-10.9) and day 3 was <1.4 µg/ml. The average pre-op creatinine levels were 69.4 µmol/L (56.1-82.6) compared to 70.2 µmol/L (57.0-83.4) on day 1 and 66.1 µmol/L (52.6-79.6) on day 3, (p = 0.663). The average pre-op eGFR levels (ml/min/1.73 m2) were 82.2 (76.0-88.3) compared to 81.7 (75.6-87.8) on day 1 and 83.0 (76.8-89.2) on day 3 (p = 0.736). Samples of joint fluid aspirated from surgical drains on day 1 and day 2 showed average vancomycin levels of 224 µg/ml and 51 µg/ml respectively, significantly higher than the MIC for Staph aureus. Conclusions: The use of intra-articular vancomycin is safe in primary TJA, with no renal damage and delivers levels within the joint which are highly therapeutic for at least 48 h post injection.

A comparison of anterior cervical discectomy and corpectomy in patients with multilevel cervical spondylotic myelopathy.

BACKGROUND: The optimal surgical approach for multilevel cervical spondylotic myelopathy (CSM) has not been defined, and the relative merits of multilevel anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy (2-level or skip 1-level corpectomy) and fusion (ACCF) remain controversial. However, few comparative studies have been conducted on these two surgical approaches. METHODS: This study retrospectively reviewed the case histories of 120 patients that underwent surgical treatment for 3- or 4-level CSM from July 2003 to June 2008. One hundred and twenty patients (81 male and 39 female) of mean age 58.3±9.8 years (37-78) were included. The study compared perioperative parameters (blood loss, operation times), complications [surgery-related complications (CSF, hoarseness, epidural hematoma, C5-palsy, dysphagia), instrumentation and graft related complications (dislodgement, subsidence)], clinical parameters [Japanese Orthopedic Association (JOA) scores, Neck Dysfunciton Index (NDI) scores], and radiologic parameters (segmental lordosis, fusion rate). RESULTS: At a minimum of 2-year follow-up, both ACDF and ACCF groups demonstrated a significant increase in the JOA scores (preoperatively 9.25±1.9 and 8.86±1.9, postoperatively 13.86±1.6 and 13.27±1.8, respectively), segmental lordosis (preoperatively 9.79±3.4 and 9.54±3.0, postoperatively 17.75±2.6 and 14.49±2.5, respectively) and NDI scores (preoperatively 12.56±3.0 and 12.21±3.4, postoperatively 3.44±1.7 and 5.68±2.6, respectively). Six patients (2 dislodgement, 4 subsidence) in ACCF group had instrumentation and graft related-complications and they had no obvious neurological symptoms without a second operation. Blood loss (102.81±51.3 and 149.05±74, respectively, P=0.000), NDI scores (P=0.000), and instrumentation and graft related-complications (P=0.032) were significantly lower in the ACDF group, whereas operation time (138.07±30.9 and 125.08±26.4, respectively, P=0.021) and segmental lordosis (P=0.000) were significantly greater in the ACDF group. Other parameters were not significantly different in the two groups. CONCLUSIONS: Surgical managements of 3- or 4-level CSM by ACDF or ACCF showed no significant differences in terms of achieved clinical symptom improvements, with the exception of better postoperative NDI scores in ACDF. In addition, ACDF is better than ACCF in terms of blood loss, lordotic curvature improvement and instrumentation and graft related-complication rates, with the exception of operation times.

The effect of multilevel anterior cervical fusion on neck motion.

BACKGROUND: Anterior cervical decompression and fusion (ACDF) procedures are successful in treating multilevel cervical radiculopathy and cervical myelopathy. It was reported that this procedure would result in a loss of cervical range of motion. However, few studies have focused on the exact impact of multilevel (more than 3 levels) ACDF on cervical range of motion. METHODS: 29 patients underwent a 3-level or 4-level ACDF. In all the patients, preoperative active cervical ROM measurement was performed, and postoperative measurement was performed at 1-year follow-up by a CROM device. The pre- and postoperative data were compared to each other using paired t tests (α = 0.05). RESULTS: The patients had significantly less ROM after the surgery in all planes of motion. Major reduction was observed in flexion (39.5%), left and right lateral flexion (25.7 and 25.9%), with relatively minor impact on extension (18.3%), left and right rotation (14.0 and 14.4%) observed. In the three cardinal planes, major reduction was observed in the sagittal plane (28.2%) and coronal plane (25.8%), while minor impact observed in the horizontal plane (14.1%). CONCLUSIONS: The patients of cervical spondylotic myelopathy had an obvious reduction in active cervical ROM following multilevel ACDF. However, patients might not experience great difficulties in performing daily activities with regard to the loss of neck motion after fusion.

Somatosensory evoked potential from S1 nerve root stimulation.

The objective of this study was to detect cerebral potentials elicited by proximal stimulation of the first sacral (S1) nerve root at the S1 dorsal foramen and to investigate latency and amplitude of the first cerebral potential. Tibial nerve SEP and S1 nerve root SEP were obtained from 20 healthy subjects and 5 patients with unilateral sciatic nerve or tibial nerve injury. Stimulation of the S1 nerve root was performed by a needle electrode via the S1 dorsal foramen. Cerebral potentials were recorded twice to document reproducibility. Latencies and amplitudes of the first cerebral potentials were recorded. Reproducible cerebral evoked potentials were recorded and P20s were identified in 36 of 40 limbs in the healthy subjects. The mean latency of P20 was 19.8 ± 1.6 ms. The mean amplitude of P20-N30 was 1.2 ± 0.9 µV. In the five patients, P40 of tibial nerve SEP was absent, while well-defined cerebral potentials of S1 nerve root SEP were recorded and P20 was identified from the involved side. This method may be useful in detecting S1 nerve root lesion and other disorders affecting the proximal portions of somatosensory pathway. Combined with tibial nerve SEP, it may provide useful information for diagnosis of lesions affecting the peripheral nerve versus the central portion of somatosensory pathway.

Scaling advantage over path-integral Monte Carlo in quantum simulation of geometrically frustrated magnets.

The promise of quantum computing lies in harnessing programmable quantum devices for practical applications such as efficient simulation of quantum materials and condensed matter systems. One important task is the simulation of geometrically frustrated magnets in which topological phenomena can emerge from competition between quantum and thermal fluctuations. Here we report on experimental observations of equilibration in such simulations, measured on up to 1440 qubits with microsecond resolution. By initializing the system in a state with topological obstruction, we observe quantum annealing (QA) equilibration timescales in excess of one microsecond. Measurements indicate a dynamical advantage in the quantum simulation compared with spatially local update dynamics of path-integral Monte Carlo (PIMC). The advantage increases with both system size and inverse temperature, exceeding a million-fold speedup over an efficient CPU implementation. PIMC is a leading classical method for such simulations, and a scaling advantage of this type was recently shown to be impossible in certain restricted settings. This is therefore an important piece of experimental evidence that PIMC does not simulate QA dynamics even for sign-problem-free Hamiltonians, and that near-term quantum devices can be used to accelerate computational tasks of practical relevance.

Neck motion following multilevel anterior cervical fusion: comparison of short-term and midterm results.

OBJECT: Multilevel anterior cervical decompression and fusion is indicated for patients with multilevel compression or stenosis of the spinal cord. Some have reported that this procedure would lead to a loss of cervical range of motion (CROM). However, few studies have demonstrated the exact impact of the procedure on CROM. Here, the authors describe short- and midterm postoperative CROM following multilevel anterior cervical decompression and fusion. METHODS: Thirty-five patients underwent a 3- or 4-level anterior cervical decompression and fusion. In all patients, active CROM was measured preoperatively and at both the short-term (3-4 months) and midterm (12-15 months) follow-ups by using a CROM device. The preoperative and postoperative data were analyzed using ANOVA (α = 0.05). RESULTS: Patients had significantly less ROM in all planes of motion postoperatively. The greater limitation in CROM was observed at the short-term follow-up. However, at the midterm follow-up, an obvious increase in CROM was observed in each cardinal plane compared with that in the short-term (sagittal plane 17.4%, coronal plane 14.1%, and horizontal plane 19.5%). A gradual increase in the CROM in each cardinal plane was observed during the recovery period in 5 patients. In the 6 conventional motions, the major recovery of CROM was observed in flexion (27.5%), while relatively less recovery was seen in extension (10.5%). CONCLUSIONS: Patients had an obvious reduction in active CROM following multilevel anterior cervical decompression and fusion. The greater limitation in CROM was observed at the short-term follow-up. In the midterm follow-up, however, an obvious recovery in CROM was observed in each cardinal plane, reducing the restriction of neck motion further.

A comparison of the Gallie technique and casting versus the harms technique for the treatment of odontoid fractures.

OBJECTIVE: The objective of this study was to compare perioperative, clinical parameters, complications, and reoperation rate of the Gallie technique and head-neck-chest plaster with the Harms technique in the treatment of odontoid fractures. DESIGN: A retrospective study. SETTING: Level I spine center. PATIENTS: Fifty-seven patients with odontoid fractures treated either with the Gallie technique and casting or the Harms technique between July 2002 and June 2008. INTERVENTION: Surgery. MAIN OUTCOME MEASUREMENTS: At a minimum of 2-year follow-up, comparison of the two groups was conducted in terms of hospital stay, blood loss, operation time, cost of the first admission, total cost, time to fusion, time to return to previous occupation, Japanese Orthopedic Association scores, visual analog scale scores of neck pain, complications (nonunion, delayed union, hardware breakage, wound infection), and reoperation rate. RESULTS: There were no significant differences in terms of hospital stay, time to fusion, Japanese Orthopedic Association scores, neck pain visual analog scale scores, complications, or reoperation rate between the two groups. Blood loss, operation time, cost of the first admission, and total cost were significantly lower in the Gallie group than that in the Harms group. However, the Gallie group took longer to return to previous occupation than the Harms group (P < 0.001). CONCLUSIONS: Management of odontoid fractures by either the Gallie technique and casting or the Harms technique was found to be similar in clinical outcomes. Although the Harms technique was associated with more blood loss, operation time, and cost, the Harms technique was found to be superior to the Gallie technique with casting in terms of time to return to previous occupation.

Desmoplastic fibroma of the cervical spine: case report and review of the literature.

STUDY DESIGN: A case report and literature review are presented. OBJECTIVE: To present a rare case of desmoplastic fibroma (DF) in the cervical spine and discuss the diagnosis and treatment of this disorder. SUMMARY OF BACKGROUND DATA: DF is an extremely rare primary tumor of bone, especially in cervical spine. It is a benign but locally aggressive tumor of the connective tissue. It has a predilection for the mandible and the metadiaphyses of long bones. It has a propensity for local recurrence, especially after intralesional resection. METHODS: We report on a 70-year-old woman with a DF of the fourth and fifth cervical vertebrae. The patient complained of progressive neck pain and limitation of activity. After radiologic evaluation, a mass lesion was found on the fourth and fifth cervical vertebral bodies. A 2-level corpectomy with wide marginal resection of the tumor was performed through the anterior approach, and the histopathologic examination yielded the diagnosis of DF. Reconstruction was achieved with a long titanium mesh and locking plate with autologous iliac crest bone graft. RESULTS: After surgery, pain was completely relieved, and neurologic function was normal. The postoperative course was uneventful, and the patient has been well without recurrence for 35 months of follow-up evaluation. CONCLUSION: Patients with DF of the cervical spine may present with the arm and neck pain mimicking cervical disc disease. High index of suspicion by the clinicians must be practiced to make the appropriate diagnosis, and histologic confirmation of the diagnosis is essential. Surgical resection with wide margins is the preferred treatment.

The influence of ambient theater temperature on cement setting time.

We have prospectively recorded ambient operating theater temperature from 186 total knee arthroplasties and the time taken for the cement to set at implantation. The majority of cases used Antibiotic Simplex cement (n = 131), and the rest, Simplex with tobramycin (n = 55). Set time was defined as when a no. 15 scalpel could not indent the cement surface at either the femoral or tibial interface. There was a reasonable negative correlation between temperature and setting time (Antibiotic Simplex: Pearson correlation coefficient, R = -0.674; Simplex with tobramycin: R = -0.655). There was also a considerable variation of setting time at any given theater temperature. There is an inverse relationship between ambient theater temperature and the setting time for Simplex cement, and surgeons should be aware that the setting time can vary considerably. Their operative protocol should take this into account.