Proximal Junction Research Articles

Surgical Management of Recurrent Musculotendinous Hamstring Injury in Professional Athletes.

Background:Hamstring injury is the most common muscular lesion in athletes. The conservative treatment is well described, and surgical management is often indicated for proximal tendinous avulsions. To our knowledge, no surgical treatment has been proposed for failure of conservative treatment in musculotendinous hamstring lesions.Purpose:To describe the surgical management of proximal and distal hamstring musculotendinous junction lesions in professional athletes after failure of conservative treatment.Study Design:Case series; Level of evidence, 4.Methods:A consecutive series of 10 professional athletes, including 4 soccer players, 4 rugby players, and 2 handball players, underwent surgical intervention between October 2010 and June 2014 for the treatment of recurrent musculotendinous hamstring injuries. All athletes had failed at least 3 months of conservative treatment for a recurrent musculotendinous hamstring injury. Surgical resection of the musculotendinous scar tissue was performed using a longitudinal muscular suture. Lower Extremity Functional Scale (LEFS) and Marx scores were obtained at the 3-month follow-up, and a final phone interview was completed to determine recurrence of hamstring injury and return to previous level of play.Results:The mean age at surgery was 25.2 years (range, 19-35 years). The musculotendinous hamstring lesions involved 8 semitendinosus and 2 biceps femoris, with 6 injuries located proximally and 4 distally. Conservative treatment lasted a mean 5.1 months (range, 3-9 months) after last recurrence, and the patients had an average of 2.7 (range, 2-5) separate incidents of injury recurrence before surgical intervention was decided upon. At the 3-month follow-up, all patients had Marx activity scores of 16 and LEFS scores of 80. All 10 patients returned to the same level of play at a mean 3.4 months (range, 2-5 months). At a mean follow-up of 28.7 months, none of the athletes had suffered a recurrence. No surgical complication was encountered.Conclusion:In cases of failed conservative treatment of musculotendinous hamstring lesions, surgical intervention may be a viable treatment option in professional athletes and allows the patient to return to the same level of play.

Prevention of Acute Proximal Junctional Fractures After Long Thoracolumbar Posterior Fusions for Adult Spinal Deformity Using 2-level Cement Augmentation at the Upper Instrumented Vertebra and the Vertebra 1 Level Proximal to the Upper Instrumented Vertebra.

Retrospective cohort analysis. To evaluate efficacy of proximal junction fracture (PJF) prevention in adult spinal deformity (ASD) using 2-level cement augmentation at the construct's proximal extent. Prevention of PJF after thoracolumbar fusions is critical because they may result in neurological injury. Cement augmentation of constructs' proximal vertebrae is postulated to decrease PJF. Patients with ASD after PSF from pelvis to thoracolumbar junction with 6 months or more follow-up were retrospectively studied. Demographics, deformity radiographical parameters, and health-related quality of life outcomes (HRQoL) scores were compared with patients with no cement, 2-level cement augmentation at upper instrumented vertebra (UIV) and vertebra 1 level proximal to UIV (UIV+1), and cement at another location ("Other"). Revision surgery for PJF was primary outcome. Univariable and multivariable logistic regression analyses were used for statistical analysis. 51 patients [female-29; male-22; average age: 65 yr (33-82)] met inclusion criteria (2-level-19; no-cement-23; "Other"-9). Average follow-up (mo) was longer for no-cement (25 ± 15) and "Other" (20 ± 16) than 2-level (15 ± 8) (P = 0.06). All perioperative radiographical parameters were similar, save first postoperative thoracic kyphosis and lumbopelvic mismatch. Compared with 2-level cement, non-2-level cement had significantly more revisions for PJF (0% vs. 19%; P = 0.02). After UIV adjustment, risks of PJF revision surgery were 13.1 times higher for "Other" (95% CI: 0.5-346.5, P = 0.12) and 9.2 times higher (95% CI: 0.4-239.1, P = 0.18) for no-cement. All HRQoL scores improved in 2-level cement; only back/leg pain significantly improved in non-2-level cement. Postoperative Oswestry Disability Index was significantly less in 2-level cement. The use of 2-level cement augmentation (UIV and UIV+1) in PSF from pelvis to thoracolumbar junction for ASD is associated with a decreased rate of acute proximal junctional fractures and associated revision surgeries. As only associations can be demonstrated from this study's design, prospective investigations with larger, consecutive cohorts should be performed to explore causal relationships. 3.

Development of Validated Computer Based Preoperative Predictive Model for Proximal Junction Failure or Clinically Significant Proximal Junction Kyphosis with 86% Accuracy Based on 510 Adult Spinal Deformity Patients with Two-Year Follow-Up

Development of Validated Computer Based Preoperative Predictive Model for Proximal Junction Failure or Clinically Significant Proximal Junction Kyphosis with 86% Accuracy Based on 510 Adult Spinal Deformity Patients with Two-Year Follow-Up

Measurement Variability in the Evaluation of the Proximal Junction in Distraction-based Growing Rods Patients.

Proximal junctional kyphosis (PJK) is a known complication of spinal fusion and has been shown to occur in the setting of growing rod instrumentation. Previous studies have shown good reliability in measuring PJK in adolescent idiopathic scoliosis. Four pediatric orthopaedic spine surgeons measured the proximal junction in 10 patients with growing rod instrumentation using 2 methods. In method 1, measurements were made from the inferior endplate of the upper instrumented vertebrae (UIV) to the superior endplate of 1 level above the UIV. In method 2, measurements were made from the inferior endplate 2 levels below the UIV to the superior endplate 2 levels above the UIV. These measurements were repeated 1 week later. Method 1 had an intraobserver variability of ±13.2 degrees and interobserver variability of ±21.6 degrees, whereas method 2 had an intraobserver variability of ±18.3 degrees and interobserver variability of ±20.7 degrees. Interobserver variability of PJK is >20 degrees. As PJK is commonly defined as >10 degrees of kyphosis above the UIV, measurement of PJK in patients with distraction-based growing rods on lateral radiographs has too much variability to be useful. Level III-diagnostic studies.

Radiological Outcomes in Adolescent Idiopathic Scoliosis Patients More Than 22 Years After Treatment

Study DesignLongitudinal cohort. ObjectivesTo evaluate the long-term radiologic outcomes in adolescent idiopathic scoliosis (AIS) patients more than 22 years after treatment. Summary of Background DataAlthough treatment for AIS is prophylactic and is aimed at preventing curve progression, very few studies report long-term outcomes of treatment. MethodsAIS patients treated with Boston brace or posterior spinal fusion (PSF) with Harrington–dorso-transverse traction (DTT) instrumentation from 1983 to 1990 were requested to return to clinic. Subsequently, 36-inch standing radiographs were obtained after patient consent. Cobb angles were compared with pretreatment and immediate posttreatment radiographs. Any evidence of adjacent-level disease or local kyphosis was also noted. ResultsOne hundred fifty-nine (78%) of 219 patients were available for follow-up, 66 braced and 93 surgical. There were 85 females with an average age at surgery of 14.3 years and an average age at follow-up of 37.6 years. The mean length of follow-up was 24.5 years (range, 22–30 years). There was a statistically significant curve progression of 2.9° in the PSF group. There was a greater degree of curve progression in the braced group (5.5°), but this was not statistically significant. Proximal segment degeneration was seen in 8 (5%), 2 in the brace cohort and 6 in the PSF cohort. Distal segment degeneration was seen in 26 (16%) patients, 4 treated with brace and 22 treated with PSF. No patient developed proximal junction kyphosis. Three patients in the PSF cohort required additional surgery for distal adding-on. Four patients had a noncontiguous L5–S1 fusion, three from the PSF cohort and one from the braced cohort. ConclusionIn this cohort with an average follow-up of 24.5 years, with 78% available for follow-up, both the braced and surgically treated patients had a very small degree of curve progression, with a small incidence of distal segment degeneration and reoperation. Level of EvidenceIII.

Evaluation of Proximal Junctional Kyphosis following Posterior Thoracic Instrumentation: The Effect of Posterior Anatomical Structures and Facet Joints: A Biomechanical Analysis on Fresh Sheep Spine

Introduction Proximal junctional kyphosis (PJK) has traditionally been defined by a 10 degree or greater increase in kyphosis at the proximal junction as measured according to Cobb method. Especially patients who have advanced spine deformity are prone to PJK and it is related with aggressive treatment protocols. In this biomechanical study, we aimed to evaluate interspinous ligament complex disruption and facet joint degeneration on PJK development. Material and Methods Randomly selected 21 sheeps were operated via posterior approach and pedicle screws were instrumented from T2 to T7. Three groups with seven samples were established to create junctional disruption. First group selected as control group (CG), of which posterior soft tissue and facet joints were preserved intact. In the second group (spinous group, SG), interspinous ligament complex which one segment cranial to UIV has been transected, and third group (facet group FG) where facet joint excision was performed. 25 N, 50 N, 100 N, 150 N, and 200 N forces applied at frequency of 5 Hz as 100 cycles axial to the samples. To determine strength of proximal junctional area in static loading 250 N, 275 N, and 300 N forces was applied. Changes in the proximal junctional region were defined radiologically. Lateral X-ray views were taken to measure interspinous distances, kyphosis angles, and discus heights. Abnormal PJK was defined by a proximal junctional angle greater than 10 degree and at least 10 degree greater than the corresponding preoperative measurement. Results In CG group, average interspinous distance was 6.6 ± 1.54 mm and kyphosis angle was 2.2 ± 0.46 degree before biomechanical testing, and they were measured as 9.4 ± 1.21 mm and 3.3 ± 0.44 degree respectively after forces applied to samples. In SG group, average interspinous distance was 6.2 ± 1.71 mm and kyphosis angle was 2.7 ± 1.09 degree before the experiment, and they were measured as 20.8 ± 5.66 mm and 15.1 ± 2.33 degrees, respectively, after biomechanical testing. In FG group, average interspinous distance was 4.8 ± 1.15 mm and kyphosis angle was −1 ± 4.14 degree before experiment, and they were measured as 11.1 ± 1.96 mm and 11 ± 2.87 degree, respectively, after forces applied to samples. Statistically significantly junctional kyphosis development was detected on both FG and SG group than group control group ( p < 0.05). PJK was seen significantly more frequently on SG group than FG group ( p < 0.05). Disc distances were similar in all groups ( p > 0.05). Conclusion Protecting interspinous ligament complex and facet joint on surgical treatment of spine deformity is mandatory to prevent PJK. To our knowledge, this is the first biomechanical study that reveals that the interspinous ligament complex is more effective in preventing PJK development than facet joints.

Analysis of Results and Complications in Patients with Scheuermann Disease Treated with Posterior Fixation

Introduction The selection of fusion levels in thoracic kyphosis been controversial, the incidence of juvenile kyphosis ranges from 1 to 8% being more common in males. Patients and Methods This study is a retrospective study case series type, level of evidence IV. We evaluated 15 patients with Scheuermann disease treated with posterior transpedicular fixation and osteotomies. Overall, two cases were excluded for not meeting the minimum monitoring time 2 years. The average age at time of surgery was 16.2 years. Patients were evaluated clinically and radiologically pre- and postsurgery to assess results and determine common factors of complications. Results In the series studied found that the percentage correction achieved was 49%, with a loss of correction 3 degrees at follow-up, the incidence of PJK was 23%, two of three patients presented the following factors in common: apex above T5, cervical hyperlordosis, SVA more than 4 cm, increased pelvic incidence, stiffness deformity, proximal fixation with hooks above T3, in the third case ended with pedicle screws. Conclusion Transpedicular fixation system and posterior spinal osteotomy is effective for the treatment of kyphosis by Scheuermann disease; the power of this type of correction techniques may arise in the pediatric population increased incidence of proximal junction kyphosis in patients with highest apex, curve stiffer, cervical hyperlordosis, and lower percentage of correction.

Instrumentation Strategies to Reduce the Risks of Proximal Junctional Kyphosis in Adult Scoliosis: A Detailed Biomechanical Analysis

Study DesignBiomechanical analysis of proximal junctional kyphosis (PJK) through numerical simulations. ObjectivesAssessment of the effect of sagittal alignment, the upper instrumented vertebral level (UIV), and 4 other surgical variables on biomechanical indices related to the PJK risks. Summary of Background DataDespite retrospective clinical studies, biomechanical analysis of individual parameters associated with PJK is lacking to support instrumentation strategies to reduce the PJK risks. MethodsInstrumentations of 6 adult scoliosis cases with different operative strategies were simulated (1,152 simulations). Proximal junctional (PJ) angle and flexion loads were evaluated against the sagittal alignment and the proximal instrumentation level. ResultsInstrumenting 1 more proximal vertebra allowed the PJ angle, proximal moment, and force to be reduced by 18%, 25%, and 16%, respectively. Shifting sagittal alignment by 20 mm posteriorly increased the PJ angle and proximal moment by 16% and 22%, and increased the equivalent posterior extensor force by 37%. Bilateral complete facetectomy, posterior ligaments resection, and the combination of the 2 resulted in an increase of the PJ angle (by 10%, 28%, and 53%, respectively), flexion forces (by 4%, 12%, and 22%, respectively), and proximal moments (by 16%, 44%, and 83%, respectively). Transverse process hooks at UIV compared with pedicle screws allowed 26% lower PJ angle and flexion loads. The use of proximal transition rods with proximal diameter reduced from 5.5 to 4 mm slightly reduced PJ angle, flexion force, and moment (less than 8%). The increase in sagittal rod curvature from 10° to 40° increased the PJ angle (from 6% to 19%), flexion force (from 3% to 10%), and moment (from 9% to 27%). ConclusionsSimulated posteriorly shifted sagittal alignment was associated with higher PJK risks, whereas extending instrumentation proximally allowed a lower mechanical risk of PJK. Preserving PJ intervertebral elements and using a more flexible anchorage at UIV help reduce the biomechanical risks of PJK.

Acute hamstring injury in football players: Association between anatomical location and extent of injury-A large single-center MRI report.

To describe in detail the anatomic distribution of acute hamstring injuries in football players, and to assess the relationship between location and extent of edema and tears, all based on findings from MRI. Retrospective observational study. We included 275 consecutive male football players who had sustained acute hamstring injuries and had positive findings on MRI. For each subject, lesions were recorded at specific locations of the hamstring muscles, which were divided into proximal or distal: free tendon, myotendinous junction, muscle belly, and myofascial junction locations. For each lesion, we assessed the largest cross-sectional area of edema and/or tears. We calculated the prevalence of injuries by location. The relationships between locations and extent of edema and tears were assessed using a one-sample t-test, with significance set at p<0.05. The long head of biceps femoris (LHBF) was most commonly affected (56.5%). Overall, injuries were most common in the myotendinous junction and in proximal locations. The proximal myotendinous junction was associated with a greater extent of edema in the LHBF and semitendinosus (ST) muscles (p<0.05). Proximal locations in the LHBF had larger edema than distal locations (p<0.05). Distal locations in the ST muscle had larger tears than proximal locations (p<0.05). The proximal myotendinous junction (LHBF and ST muscles) and proximal locations (LHBF muscle) are more commonly affected and are associated with a greater extent of edema in acute hamstring muscle injury. Distal locations (ST muscle), however, seem to be more commonly associated with larger tears.

A computational study of pressure wave reflections in the pulmonary arteries.

Experiments using wave intensity analysis suggest that the pulmonary circulation in sheep and dogs is characterized by negative or open-end type wave reflections, that reduce the systolic pressure. Since the pulmonary physiology is similar in most mammals, including humans, we test and verify this hypothesis by using a subject specific one-dimensional model of the human pulmonary circulation and a conventional wave intensity analysis. Using the simulated pressure and velocity, we also analyse the performance of the P-U loop and sum of squares techniques for estimating the local pulse wave velocity in the pulmonary arteries, and then analyse the effects of these methods on linear wave separation in the main pulmonary artery. P-U loops are found to provide much better estimates than the sum of squares technique at proximal locations, but both techniques accumulate progressive error at distal locations away from heart, particularly near junctions. The pulse wave velocity estimated using the sum of squares method also gives rise to an artificial early systolic backward compression wave. Finally, we study the influence of three types of pulmonary hypertension viz. pulmonary arterial hypertension, chronic thromboembolic pulmonary hypertension and pulmonary hypertension associated with hypoxic lung disease. Simulating these conditions by changing the relevant parameters in the model and then applying the wave intensity analysis, we observe that for each group the early systolic backward decompression wave reflected from proximal junctions is maintained, whilst the initial forward compression and the late systolic backward compression waves amplify with increasing pathology and contribute significantly to increases in systolic pressure.

Prevention of proximal junctional kyphosis after posterior surgery of Scheuermann kyphosis: an operative technique.

A prospective randomized study. To introduce an operative technique that prevents proximal junctional kyphosis (PJK) in Scheuermann disease after a segmental posterior spinal instrumentation and fusion. PJK is the progression of kyphotic deformity at the proximal end of a construct >10 degrees, and it can be seen up to 30% after posterior Scheuermann kyphosis surgery. After posterior fusion the biomechanics of the spine changes and the loss of motion at the fused levels is compensated by increased motion at other unfused segments. As a result significant amount of additional force is placed on the proximal junction. With our operative technique, we aimed to have a smooth passage from rigid to mobile segments and to decrease the stress on proximal junction during cantilever reduction to prevent PJK. A total of 60 consecutive patients (mean age: 18.27±3.19, male/female: 28/32) who were surgically treated for Scheuermann kyphosis in our institution were recruited into this study and were prospectively evaluated. Patients were divided into 2 groups according to upper-most screw fixation technique. In group 1, a standard screw insertion technique was used (ST group). The technique was modified in group 2 (MT group), leaving 2 threads out of the posterior cortex. There were 29 patients in group 1 (ST) and 31 patients in group 2 (MT). Patients had an average follow-up time of 24.2 months (range, 19-48 mo). Evaluated radiographic parameters were preoperative and postoperative kyphosis angle, and proximal junctional angle (PJA) at last visit. PJA was defined as the angle between the caudal endplate of the upper instrumented vertebra and the cephalad endplate of 2 suprajacent vertebrae above the upper instrumented vertebra. PJA exceeding 10 degrees was accepted as PJK. Quality of life measurement was assessed preoperatively and postoperatively with SF-36 questionnaire. Correction amounts in ST group and MT group were 46.8% and 43.7%, respectively, which was statistically insignificant. The mean PJA was 8.08±2.96 degrees and 4.44±1.55 degrees in ST and MT groups, respectively, which demonstrated a statistically significant difference (P=0.001). Five patients in ST group had a PJA exceeding 10 degrees (PJK), whereas PJK was not seen in MT group (P=0.022). The improvement in physical component summary of SF-36 was significantly better in MT group; however, mental component summary was similar in both groups. This study introduces a new technique that may have an effect in preventing PJK. Our results seem to be satisfactory, but additional studies with more patients and longer follow-up times are needed to further delineate the feasibility of this technique.

Screw Fixation Diameter for Fifth Metatarsal Jones Fracture: A Cadaveric Study

The fifth metatarsal Jones fracture is a well-documented injury occurring at the proximal diaphyseal-metaphyseal junction. Conservative versus surgical intervention has been discussed in published studies for the management of Jones fractures. Solid intramedullary fixation relies on accurate matching of the screw diameter to the intraosseous diameter. The purpose of the present cadaveric study was to determine the average intraosseous diameter of the proximal fifth metatarsal as it relates to screw size selection for Jones fracture stabilization. Twenty fresh-frozen cadaver legs were used for examination. The fifth metatarsal was completely dissected. A transverse osteotomy was performed from laterally to medially along the midline of the metatarsal. A digital caliper was used to measure the diameter of the medullary canal of the fifth metatarsal. The measurement was taken at the narrowest portion of the medullary canal just distal to the proximal metaphysis. The mean dorsal to plantar diameter of the fifth metatarsal was 6.475 ± 1.54 (range 4 to 12) mm and the mean medial to lateral diameter was 4.6 ± 0.85 (range 3 to 6) mm. Intramedullary screw fixation has shown beneficial results in the treatment protocol of fifth metatarsal Jones fractures. Our study has demonstrated that a 4.5-mm cannulated screw is the narrowest diameter screw that can be used in the average fifth metatarsal and still obtain adequate intraosseous purchase. When selecting the appropriate screw, the surgeon must be comfortable selecting the largest screw that will achieve the maximal interface with the dense cortical bone in both the medial to lateral and dorsal to plantar plane.

What Is the Association Between Sports Participation and the Development of Proximal Femoral Cam Deformity?

Background: Femoroacetabular impingement (FAI) is recognized as a common cause of hip pain and intra-articular disorders in athletes. Studies have suggested a link between participation in athletics during adolescence and the development of cam-type deformities of the proximal femoral head-neck junction. Purpose: To investigate the association of sporting activity participation during adolescence and the development of cam deformity. Study Design: Systematic review. Methods: The PubMed, EMBASE, and Cochrane databases were searched to identify potential studies. s and manuscripts (when applicable) were independently reviewed by 2 reviewers. Nine studies met the inclusion criteria, including 8 studies that compared the prevalence of cam deformity in athletes with that in controls and 3 studies that compared the prevalence of cam deformity before and after physeal closure (2 with both). A meta-analysis was performed with pooling of data and random-effects modeling to compare rates of cam deformity between athletes and controls. Results: High-level male athletes are 1.9 to 8.0 times more likely to develop a cam deformity than are male controls. The pooled prevalence rate (by hip) of cam deformity in male athletes was 41%, compared with 17% for male controls. The pooled mean alpha angle among male athletes was 61°, compared with 51° for male controls. Conclusion: Males participating in specific high-level impact sports (hockey, basketball, and possibly soccer) are at an increased risk of physeal abnormalities of the anterosuperior head-neck junction that result in a cam deformity at skeletal maturity.

Preventing proximal junctional failure in long segmental instrumented cases of adult degenerative scoliosis using a multilevel stabilization screw technique.

Background:The authors sought to demonstrate the safety and effectiveness of the multilevel stabilization screw (MLSS) technique in decreasing the incidence of proximal junctional failure in long segmental instrumented fusions for adult degenerative scoliosis.Methods:Institutional review board approval was obtained and all patients with adult spinal deformity who underwent the MLSS technique were analyzed. A neuro-radiologist and spine-focused neurosurgeon not involved with the surgical treatment performed radiographic analysis. Proximal junctional angle was defined as the caudal endplate of the upper instrumented vertebra (UIV) to the cephalad endplate of two supradjacent vertebrae above the UIV. The UIV is defined as the most cephalad vertebra completed captured by the instrumentation. Abnormal proximal junctional kyphosis (PJK) was defined as proximal junctional sagittal Cobb angle >10 degrees and proximal junction sagittal Cobb angle at least 10 degrees greater than the preoperative measurement. The presence of both is criteria necessary to be considered abnormal.Results:Twenty patients with degenerative scoliosis underwent the MLSS technique with the upper-instrumented vertebrae in the proximal thoracic spine. Fifteen patients met inclusion criteria with greater than 12 months radiographic and clinical follow up. Three patients were excluded due to lack of follow up imaging and two patients were excluded due to the inability to measure the UIV. Age range was 44–84 years with a mean of 66. Eleven of the 15 patients were over the age of 60 at the time of surgery. The male-to-female ratio was 4:11. Body mass index (BMI) range was 24–44 with a mean of 31.5 units. The follow up period ranged from 14 to 58 months with an average follow up of 30 months. The mean change in Cobb angle at the proximal junction was 4.00 degrees with a range from -0.92 to 9.13 degrees. There were no fractures or instrumentation failures at or near the proximal junction. There was no revision surgeries performed for proximal junctional failure. Retrospective clinical questionnaires revealed that surgical expectations were met in 15 of 19 patients surveyed, 79%. One patient was not reachable for a postoperative phone interview. In patients who were not satisfied with their overall experience, the change in Cobb angle ranged from -0.92 to 9.13 degrees with an average change of 3.90 degrees. Whereas patients reporting an overall positive experience had a change in Cobb angle range from -0.12 to 8.07 degrees with an average change of 4.05 degrees.Conclusion:PJK and failure are well-recognized suboptimal outcomes of long-segmental fusions of the thoracolumbar spine that can lead to significant neurological morbidity and costly revision surgeries. With no known proximal junction failures to date, the MLSS technique has shown promising results in preventing adverse proximal junctional conditions and can be safely performed under fluoroscopy guidance. Future direction includes a comparative study establishing the relative risk of developing PJK with this novel technique versus a traditional long-segmental thoracolumbar fusion.

Mutation screening of PALB2 in clinically ascertained families from the Breast Cancer Family Registry.

Loss-of-function mutations in PALB2 are associated with an increased risk of breast cancer, with recent data showing that female breast cancer risks for PALB2 mutation carriers are comparable in magnitude to those for BRCA2 mutation carriers. This study applied targeted massively parallel sequencing to characterize the mutation spectrum of PALB2 in probands attending breast cancer genetics clinics in the USA. The coding regions and proximal intron-exon junctions of PALB2 were screened in probands not known to carry a mutation in BRCA1 or BCRA2 from 1,250 families enrolled through familial cancer clinics by the Breast Cancer Family Registry. Mutation screening was performed using Hi-Plex, an amplicon-based targeted massively parallel sequencing platform. Screening of PALB2 was successful in 1,240/1,250 probands and identified nine women with protein-truncating mutations (three nonsense mutations and five frameshift mutations). Four of the 33 missense variants were predicted to be deleterious to protein function by in silico analysis using two different programs. Analysis of tumors from carriers of truncating mutations revealed that the majority were high histological grade, invasive ductal carcinomas. Young onset was apparent in most families, with 19 breast cancers under 50 years of age, including eight under the age of 40 years. Our data demonstrate the utility of Hi-Plex in the context of high-throughput testing for rare genetic mutations and provide additional timely information about the nature and prevalence of PALB2 mutations, to enhance risk assessment and risk management of women at high risk of cancer attending clinical genetic services.

Proximal Tendon-Prosthesis Junction for Active Tendon Implants of the Hand: A Biomechanical Comparison of 2 Techniques

To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 tendon-prosthesis techniques used to connect the proximal tendon stump to silicone active tendon implants used in reconstruction of flexor tendons. We evaluated percent stretch following cyclic loading and at failure, stiffness during load to failure, and ultimate load of 16 tendon-prosthesis junctions using cadaveric canine flexor digitorum profundus tendons to re-create 2 junction techniques: the tendon loop (TL) and the polyester weave (PW). The TL junction showed greater percent stretch at a static load of 2 N, following 500 cycles of loading between 2 N and 50 N, and at peak load. The PW junction displayed greater stiffness from 50 to 150 N during load to failure. Both junctions failed at a mean ultimate load greater than 220 N. The described proximal junction techniques for active tendon implants were strong enough to resist early active motion in the immediate postoperative period without significant elongation. The PW technique displayed greater stiffness and ultimate load compared with the TL. Data on tendon-prosthesis characteristics of these 2 methods may aid the surgeon in choosing which junction technique to use, during surgical tensioning decisions, and in considering activity protocols after surgery. These data may also serve as a baseline for further investigations regarding active tendon implants.

Evaluation of the association between embrasure morphology and central papilla recession by radiographic method.

The objective of this study was to evaluate the association between embrasure morphology and central papilla recession. The central papilla was assessed in 372 adults using standardized periapical radiographs of the maxillary central incisors. The following vertical distances were measured: h1, papilla tip to contact point (PT-CP); h2, proximal cementoenamel junction to contact point (pCEJ-CP); h3, bone crest to contact point (BC-CP); and h4, bone crest to papilla tip (BC-PT). Vertical lines were measured along the long axis of the tooth. Horizontal distance was measured as w2 (distance between the two central incisors at the proximal CEJ level, ie, the interdental width). All participants were divided into four groups according to their w2 and h2 measurements: narrow-long (w2 ≤ 2 mm and h2 > 4 mm), narrow-short (w2 ≤ 2 mm and h2 ≤ 4 mm), wide-long (w2 > 2 mm and h2 > 4 mm), and wide-short (w2 > 2 mm and h2 ≤ 4 mm). A statistically significant positive relationship was evident between central papilla recession and age, and a statistically significant negative relationship was evident between age and papilla height in all study groups. The study found that occurrence of central papilla recession is significantly related to age with a wide interdental width and long pCEJCP distance. However, other factors also determine whether the interdental papilla is present or not, and further study of the interaction among these factors is warranted.

Musculotendon variability influences tissue strains experienced by the biceps femoris long head muscle during high-speed running

The hamstring muscles frequently suffer injury during high-speed running, though the factors that make an individual more susceptible to injury remain poorly understood. The goals of this study were to measure the musculotendon dimensions of the biceps femoris long head (BFlh) muscle, the hamstring muscle injured most often, and to use computational models to assess the influence of variability in the BFlh’s dimensions on internal tissue strains during high-speed running. High-resolution magnetic resonance (MR) images were acquired over the thigh in 12 collegiate athletes, and musculotendon dimensions were measured in the proximal free tendon/aponeurosis, muscle and distal free tendon/aponeurosis. Finite element meshes were generated based on the average, standard deviation and range of BFlh dimensions. Simulation boundary conditions were defined to match muscle activation and musculotendon length change in the BFlh during high-speed running. Muscle and connective tissue dimensions were found to vary between subjects, with a coefficient of variation (CV) of 17±6% across all dimensions. For all simulations peak local strain was highest along the proximal myotendinous junction, which is where injury typically occurs. Model variations showed that peak local tissue strain increased as the proximal aponeurosis width narrowed and the muscle width widened. The aponeurosis width and muscle width variation models showed that the relative dimensions of these structures influence internal muscle tissue strains. The results of this study indicate that a musculotendon unit’s architecture influences its strain injury susceptibility during high-speed running.

Charge transport in InAs nanowire Josephson junctions

We present an extensive experimental and theoretical study of the proximity effect in InAs nanowires connected to superconducting electrodes. We fabricate and investigate devices with suspended gate-controlled nanowires and nonsuspended nanowires, with a broad range of lengths and normal-state resistances. We analyze the main features of the current-voltage characteristics: the Josephson current, excess current, and subgap current as functions of length, temperature, magnetic field, and gate voltage, and compare them with theory. The Josephson critical current for a short-length device, L = 30 nm, exhibits a record high magnitude of 800 nA at low temperature that comes close to the theoretically expected value. The critical current in all other devices is typically reduced compared to the theoretical values. The excess current is consistent with the normal resistance data and agrees well with the theory. The subgap current shows a large number of structures; some of them are identified as subharmonic gap structures generated by multiple Andreev reflection. The other structures, detected in both suspended and nonsuspended devices, have the form of voltage steps at voltages that are independent of either the superconducting gap or length of the wire. By varying the gate voltage in suspended devices, we are able to observe a crossover from typical tunneling transport at large negative gate voltage, with suppressed subgap current and negative excess current, to pronounced proximity junction behavior at large positive gate voltage, with enhanced Josephson current and subgap conductance as well as a large positive excess current.

Transverse Process Hooks at Upper Instrumented Vertebra Provide More Gradual Motion Transition Than Pedicle Screws

Biomechanical study in a porcine model. To determine whether transverse process hooks (TPHs) placed at the proximal end of a long posterior spinal fusion construct provide a more gradual transition to normal motion of the adjacent cephalad motion segment compared with an all pedicle screw (APS) construct. Proximal junctional kyphosis after instrumentation with long posterior spinal constructs has been increasingly associated with incidence of adjacent segment pathologies. Clinical studies have suggested that proximal anchor type may affect the incidence of proximal junctional kyphosis. Biomechanical tests were conducted on porcine thoracic spines before and after implantation of a long spinal fusion construct. In all specimens, dual long rods (Co-Cr) were implanted posteriorly using pedicle screws at T7-T15. Upper instrumented vertebra, T6, received either TPHs (n = 7) or pedicle screws (APSs) (n = 6). Each specimen was tested in flexion-extension then lateral bending. Moments were applied, and vertebral displacements were recorded. Range of motion (ROM) and stiffness (K) were determined for each motion segment. Differences between TPH and APS at the transition were determined using t tests. In flexion-extension, ROM at the most proximal instrumented motion segment was 9% of control for APS versus 21% of control for TPH. Difference between APS and TPH at UIV was 0.5° (P < 0.008). Stiffness of TPH at T6-T7 was significantly lower than APS in FE (P < 0.003). For APS, the greatest mean ROM occurred at the first uninstrumented segment, whereas TPH maintained the pattern of monotonic increases in mean ROM from distal to proximal. TPHs at the upper instrumented vertebra provided a more gradual transition to normal motion compared with pedicle screws in long posterior spinal fusion constructs. TPH at the upper instrumented vertebra may be postulated to decrease the incidence of postoperative proximal junctional kyphosis compared with APS. N/A.