The effects of RF coils and SAR supervision strategies for clinically applicable nonselective parallel-transmit pulses at 7 T

PURPOSE

To investigate the effects of using different parallel-transmit (pTx) head coils and specific absorption rate (SAR) supervision strategies on pTx pulse design for ultrahigh-field MRI using a 3D-MPRAGE sequence.

METHODS

The PTx universal pulses (UPs) and fast online-customized (FOCUS) pulses were designed with pre-acquired data sets (B₀ , B₁ ⁺ maps, specific absorption rate [SAR] supervision data) from two different 8 transmit/32 receive head coils on two 7T whole-body MR systems. For one coil, the SAR supervision model consisted of per-channel RF power limits. In the other coil, SAR estimations were done with both per-channel RF power limits as well as virtual observation points (VOPs) derived from electromagnetic field (EMF) simulations using three virtual human body models at three different positions. All pulses were made for nonselective excitation and inversion and evaluated on 132 B₀ , B₁ ⁺ , and SAR supervision datasets obtained with one coil and 12 from the other. At both sites, 3 subjects were examined using MPRAGE sequences that used UP/FOCUS pulses generated for both coils.

RESULTS

For some subjects, the UPs underperformed when simulated on a different coil from which they were derived, whereas FOCUS pulses still showed acceptable performance in that case. FOCUS inversion pulses outperformed adiabatic pulses when scaled to the same local SAR level. For the self-built coil, the use of VOPs showed reliable overestimation compared with the ground-truth EMF simulations, predicting about 52% lower local SAR for inversion pulses compared with per-channel power limits.

CONCLUSION

FOCUS inversion pulses offer a low-SAR alternative to adiabatic pulses and benefit from using EMF-based VOPs for SAR estimation.

Artifact suppression in readout-segmented consistent K-t space EPSI (RS-COKE) for fast 1 H spectroscopic imaging at 7 T

PURPOSE

Fast proton (¹ H) MRSI is an important diagnostic tool for clinical investigations, providing metabolic and spatial information. MRSI at 7 T benefits from increased SNR and improved separation of peaks but requires larger spectral widths. RS-COKE (Readout-Segmented Consistent K-t space Epsi) is an echo planar spectroscopic imaging (Epsi) variant capable to support the spectral width required for human brain metabolites spectra at 7 T. However, mismatches between readout segments lead to artifacts, particularly when subcutaneous lipid signals are not suppressed. In this study, these mismatches and their effects are analyzed and reduced.

METHODS

The following corrections to the data were performed: i) frequency-dependent phase corrections; ii) k-space trajectory corrections, derived from short reference scans; and iii) smoothing of data at segment transitions to mitigate the effect of residual mismatches. The improvement was evaluated by performing single-slice RS-COKE on a head-shaped phantom with a "lipid" layer and healthy subjects, using varying resolutions and durations ranging from 4.1 × 4.7 × 15 mm³ in 5:46 min to 3.1 × 3.3 × 15 mm³ in 13:07 min.

RESULTS

Artifacts arising from the readout-segmented acquisition were substantially reduced, thus providing high-quality spectroscopic imaging in phantom and human scans. LCModel fitting of the human data resulted in a relative Cramer-Rao lower bounds within 6% for NAA, Cr, and Cho images in the majority of the voxels.

CONCLUSION

Using the new reference scans and reconstruction steps, RS-COKE was able to deliver fast ¹ H MRSI at 7 T, overcoming the spectral width limitation of standard EPSI at this field strength.

Combined acquisition of diffusion and T2*-weighted measurements using simultaneous multi-contrast magnetic resonance imaging

Object

In this work, we present a technique called simultaneous multi-contrast imaging (SMC) to acquire multiple contrasts within a single measurement. Simultaneous multi-slice imaging (SMS) shortens scan time by allowing the repetition time (TR) to be reduced for a given number of slices. SMC imaging preserves TR, while combining different scan types into a single acquisition. This technique offers new opportunities in clinical protocols where examination time is a critical factor and multiple image contrasts must be acquired.

Materials and methods

High-resolution, navigator-corrected, diffusion-weighted imaging was performed simultaneously with T₂*-weighted acquisition at 3 T in a phantom and in five healthy subjects using an adapted readout-segmented EPI sequence (rs-EPI).

Results

The results demonstrated that simultaneous acquisition of two contrasts (here diffusion-weighted imaging and T₂*-weighting) with SMC imaging is feasible with robust separation of contrasts and minimal effect on image quality.

Discussion

The simultaneous acquisition of multiple contrasts reduces the overall examination time and there is an inherent registration between contrasts. By using the results of this study to control saturation effects in SMC, the method enables rapid acquisition of distortion-matched and well-registered diffusion-weighted and T₂*-weighted imaging, which could support rapid diagnosis and treatment of acute stroke.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10334-021-00976-3.

Inlay total shoulder arthroplasty for primary glenohumeral arthritis

Background

Anatomic total shoulder arthroplasty with a nonspherical humeral head and inlay glenoid replacement has been introduced in the past; however, clinical evidence remains limited. We hypothesized that patients with advanced glenohumeral arthritis demonstrate significant improvements in pain and function.

Methods

Prospective patient-reported outcomes (PROs) included the American Shoulder and Elbow Surgeons score, a pain visual analog scale, and satisfaction. Range of motion was compared to the preoperative status. A sensitivity analysis examined responder rates and compared them to literature thresholds using the minimal clinically important difference and substantial clinical benefit. The preoperative glenoid morphology was determined using the Walsh classification. Zone-specific periprosthetic radiolucent lines were quantified at the last follow-up.

Results

Thirty-nine shoulders in 36 patients (3 bilateral) with a mean age of 65.9 years (26 males, 13 females) and a mean follow-up of 41.0 months were included. Ninety-three percent had grade III osteoarthritis, and 7% grade II. The glenoid Walsh classification included A1 (25%), A2 (25%), B1 (22%), B2 (25%), and C (3%). All PROs improved significantly (P < .001) with a mean American Shoulder and Elbow Surgeons score from 30.4 to 77.1, a pain visual analog scale from 8.1 to 1.5, and excellent (9.1/10) patient satisfaction. PRO-related responder rates for minimal clinically important difference and substantial clinical benefit were ≥85%. Forward elevation improved from 107° to 155°, and external rotation from 22° to 51°. One intraoperative glenoid rim fracture led to advanced radiolucency; no other clinically relevant lucency was observed.

Conclusion

Treatment with inlay total shoulder arthroplasty demonstrated significant functional improvement, excellent pain relief, and patient satisfaction in patients with advanced shoulder arthritis and various glenoid morphology types. Our initial results provide further support for this new option in primary shoulder replacement.

Proximal Fifth Metatarsal Fractures in Athletes: Management of Acute and Chronic Conditions

Proximal fifth metatarsal fractures are common in the athlete and can be a source of significant, temporary disability and missed playing time. The pattern of fracture can vary, and the type of fracture leads to a significantly different prognosis and treatment. Jones fractures of the fifth metatarsal are particularly common and difficult to treat in the athlete, can have recurrence and refracture, and require expertise to heal. Intramedullary screw fixation is currently the preferred method of fixation. Most other (non-Jones fractures and os vesalianum) proximal fifth metatarsal fractures can be treated successfully without surgery.

Distal Clavicle Fracture Repair: Clinical Outcomes of a Surgical Technique Utilizing a Combination of Cortical Button Fixation and Coracoclavicular Ligament Reconstruction

Background:

When treated conservatively, unstable distal clavicle fractures demonstrate a high symptomatic nonunion rate. While a variety of surgical techniques have been described, many of these techniques are associated with high failure rates and hardware-related complications. The surgical technique used in this study has shown promising biomechanical results; however, long-term clinical results have not yet been described.

Purpose:

To assess the clinical and radiological outcomes of a surgical technique for fixing displaced distal clavicle fractures using a combination of cortical button fixation and coracoclavicular (CC) ligament reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

We conducted a retrospective review of 22 consecutive patients with displaced, unstable Neer type II or V distal clavicle fractures who underwent this surgical technique from 2012 to 2019. Primary outcome variables were radiographic union, patient satisfaction, and postoperative shoulder function. Preoperative and postoperative University of California, Los Angeles (UCLA), and American Shoulder and Elbow Surgeons (ASES) scores were compared. Secondary outcome variables included intraoperative complications, postoperative complications, time to radiographic union, and preoperative and postoperative CC distance. Quality of life was assessed using preoperative and postoperative 36-Item Short Form Health Survey (SF-36) scores.

Results:

Nearly all (21/22) patients were available for a final review; 1 patient was lost to follow-up at 2 weeks. All 21 patients achieved radiographic union by 4 months (mean, 60.38 days; range, 41-84 days; 95% CI, 53.80-66.96 days). All patients were satisfied with the surgical procedure and their functional outcome. The mean UCLA score improved from 5.36 (95% CI, 4.14-6.60) preoperatively to 32.52 (95% CI, 30.56-34.48) postoperatively (mean difference, 27.14; P < .001). The mean ASES score improved from 16.23 (95% CI, 9.79-22.67) preoperatively to 88.11 (95% CI, 81.82-94.40) postoperatively (mean difference, 71.91; P < .001). Statistically significant improvements in SF-36 scores were seen in the physical functioning, role limitations due to physical health, pain, social functioning, and emotional well-being categories. There were 3 postoperative complications, including 1 patient with a minor complication secondary to hardware irritation, 1 patient with adhesive capsulitis, and 1 patient with wound dehiscence requiring wound closure.

Conclusion:

We describe a surgical technique for fixing displaced distal clavicle fractures using a combination of cortical button fixation and CC ligament reconstruction that resulted in a 100% union rate and excellent clinical outcomes with acceptable complications.

A biomechanical comparison of new techniques for distal clavicular fracture repair versus locked plating

BACKGROUND

Unstable distal clavicular fractures treated surgically are associated with high failure rates and hardware-related complications. Newer techniques have shown promising early clinical results with fewer hardware complications; however, their biomechanical performance has not been assessed. This study biomechanically compared a distal-third locking plate with 3 newer techniques that incorporate coracoid fixation into the construct.

METHODS

The study randomized 36 adult fresh frozen cadaveric shoulders to 4 groups: (1) distal-third locking plate (P); (2) distal-third locking plate with a coracoid button augmentation (P + CB); (3) coracoclavicular button (CB); and (4) coracoclavicular button with coracoclavicular ligament reconstruction using semitendinosus allograft (CB + CC). After fixation, each specimen was stressed in the coronal plane. Cyclic displacement, load at 10-mm displacement, and ultimate load to failure were measured.

RESULTS

All 3 experimental groups biomechanically outperformed the locking plate. Mean load to failure was significantly higher in the CB (343 ± 76 N) and CB + CC (349 ± 94 N) groups compared with the P group (193 ± 52 N). There was also significantly less cyclic displacement in the CB (4.3 ± 1.9 mm) and CB + CC (4.4 ± 1.9 mm) groups compared with the P group (8.2 ± 2.9 mm). With respect to load at 10 mm of displacement, which essentially measures a clinical failure, the P + CB (235 ± 112 N), CB (253 ± 111 N), and CB+CC (238 ± 76 N) experimental groups significantly outperformed the P group (96 ± 29 N).

CONCLUSIONS

CB and CB + CC techniques demonstrated more than 75% greater strength than the traditional locking plate alone. Coupled with greater overall construct strength and lower-profile hardware, these newer techniques may result in improved clinical outcome and fewer hardware-related complications.

Defining the Critical Elements of the Most Common Arthroscopic Procedures: A Consensus of Orthopaedic Sports Medicine Surgeons

Objective

To define the critical elements of common procedures in arthroscopic surgery.

Methods

A survey was administered to surgeons associated with the American Orthopaedic Society for Sports Medicine (AOSSM) to determine the critical elements for four common arthroscopic procedures: anterior cruciate ligament (ACL) reconstruction, knee arthroscopy with meniscal debridement or repair, rotator cuff repair (RCR), and capsulorrhaphy for anterior glenohumeral instability (Bankart repair). Respondents were asked which steps necessitated their direct supervision. The level of experience and practice demographics were also recorded.

Results

For all applicable procedures, patient positioning and closure were not considered critical steps. Establishing arthroscopic portals was critical for all procedures, except knee arthroscopy. Diagnostic arthroscopy was only critical in ACL reconstruction. Private practice surgeons considered every step of these common procedures to be critical elements. Less experienced surgeons were more likely to regard certain aspects of a procedure critical. Surgeons with >15 years of experience considered diagnostic arthroscopy critical to all procedures, whereas those with <15 years of experience did not. Unlike surgeons with a resident as first assist, surgeons with a physician assistant (PA) or nurse practitioner (NP) found every step of each procedure to be critical except closure and positioning.

Conclusion

Across all procedures, only patient positioning and closure were consistently regarded as non-critical elements. There were significant differences in responses according to experience and practice setting. Future research is necessary to determine the implications of these findings and guide the definition of the “critical portions” of surgery.

Injury Pattern in Ligamentous Lisfranc Injuries in Competitive Athletes

BACKGROUND:

We report data on the largest cohort to date of patients who sustained a ligamentous Lisfranc injury during sport. To date, the prevalence of concurrent intercuneiform ligament injuries in the competitive athlete with subtle Lisfranc instability has not been reported.

METHODS:

Eighty-two patients (64 males, 18 females) sustained an unstable Lisfranc injury (49 left, 33 right) and met inclusion criteria. Injuries were classified as traditional dislocation (TRAD, first to second TMT ligament tear), medial column dislocation (MCD, second TMT, and medial-middle cuneiform ligament tear), or proximal extension dislocation (PE, first, second, and medial-middle cuneiform ligament tear) and the injury pattern confirmed at surgery. All athletes underwent open reduction with internal fixation (ORIF) of each unstable midfoot segment. Fisher exact tests and 2-tailed t tests were used to analyze statistical significance according to injury pattern, sport, gender difference, hindfoot angle alignment, and injured side ( P < .05).

RESULTS:

Average age of athletes was 21.0 ± 5.3 years old (range 12-40), and return to sports was 7.5 ± 2.1 months. Injury distribution was as follows: TRAD (n = 40), MCD (n = 17), and PE (n = 23). MCD trended toward a longer return to sport (8.4 ± 3.3 months, P = .074). Football was the most common sport at time of injury (n = 48). Wakeboard athletes (n = 5) were older (31.4 ± 3.2, P = .0002), and MCD tears were more prevalent among them ( P = .061). Basketball (n = 13) players were significantly younger (19.1 ± 2.5 years, P = .028) and returned to sports quicker (5.2 ± 0.7, P = .0002). Return to sport data indicated a typical population for athletes with Lisfranc injury in these sports.

CONCLUSION:

Proximal extension disruption (intercuneiform ligament tear) occurred in 50% of these low-energy Lisfranc athletic injuries. MCD and PE may be more prevalent than previously understood. This is the first study to document the extent, pattern, and prevalence of associated intercuneiform ligament tears in the competitive athlete with a low-energy subtle, unstable Lisfranc injury.

LEVEL OF EVIDENCE:

Level IV, retrospective case series.

Chronic Lateral Ankle Instability: Open Surgical Management

Open surgical reconstruction for chronic lateral ankle instability is a proven and effective means of providing renewed stability. Ankle arthroscopy is recommended before reconstruction to address intra-articular pathology. The open procedure discussed is well researched and proven to restore stability and the ability to return to sport and daily activity. Anatomic shortening with reattachment into a bony trough allows return to full motion, reliable stability, and return to an active lifestyle without sacrificing any tendons or requiring a tenodesis. The authors' aggressive rehabilitation protocol is provided; the approach to athletes/patients with ligament laxity or cavovarus alignment is also addressed.

Chronic Lateral Ankle Instability: Open Surgical Management

Open surgical reconstruction for chronic lateral ankle instability is a proven and effective means of providing renewed stability. Ankle arthroscopy is recommended before reconstruction to address intra-articular pathology. The open procedure discussed is well researched and proven to restore stability and the ability to return to sport and daily activity. Anatomic shortening with reattachment into a bony trough allows return to full motion, reliable stability, and return to an active lifestyle without sacrificing any tendons or requiring a tenodesis. The authors' aggressive rehabilitation protocol is provided; the approach to athletes/patients with ligament laxity or cavovarus alignment is also addressed.

Proximal Adductor Avulsion Injuries: Outcomes of Surgical Reattachment in Athletes

Background:

Sports-related groin injuries are common among athletes. However, traumatic proximal adductor avulsion injuries are relatively rare groin injuries in the athletic population, with limited case reports describing suture anchor repair.

Purpose:

To report on the outcomes of surgical reattachment of proximal adductor avulsion injuries in athletes utilizing a suture anchor repair technique.

Study Design:

Case series; Level of evidence, 4.

Methods:

Prospective data were collected on patients undergoing surgical reattachment of proximal adductor avulsion injuries from December 2012 to May 2015 by a single surgeon. Six athletes presented after a traumatic sports-related injury with disabling groin pain, adductor weakness, and magnetic resonance imaging confirmation of fibrocartilage avulsion of the proximal adductor with retraction. Patient-reported outcomes (Hip Outcome Score–Activities of Daily Living [HOS-ADL] and Hip Outcome Score–Sport Specific [SS] subscales, modified Harris Hip Score [mHHS], and visual analog scale [VAS] for pain) were collected preoperatively and at a minimum 2-year follow-up.

Results:

The latest follow-up of each patient averaged 33.4 months postoperatively (range, 25-42.5 months). All patients returned to sporting activities, with 1 minor wound complication that resolved. Paired-samples t tests indicated that the mean latest postoperative scores for all patients were significantly better than their mean preoperative scores (HOS-ADL: 99.0 vs 43.2, HOS-SS: 98.9 vs 8.3, and mHHS: 97.1 vs 44.6, respectively; P < .001 for all). Similarly, there was a significant improvement in mean postoperative VAS scores for all patients (from 89.2 to 2.2; P < .001).

Conclusion:

Patient-reported outcomes offer an objective measure of hip function and pain control. Surgical reattachment utilizing a multiple suture anchor technique is a successful procedure that allows for a safe return to athletic performance and a predictable return to sport.

Effect of Intraoperative Platelet-Rich Plasma Treatment on Postoperative Donor Site Knee Pain in Patellar Tendon Autograft Anterior Cruciate Ligament Reconstruction: A Double-Blind Randomized Controlled Trial

BACKGROUND

Donor site morbidity in the form of anterior knee pain is a frequent complication after bone-patellar tendon-bone (BPTB) autograft anterior cruciate ligament (ACL) reconstruction. Hypothesis/Purpose: The purpose was to examine the effect of the intraoperative administration of platelet-rich plasma (PRP) on postoperative kneeling pain. It was hypothesized that PRP treatment would reduce knee pain.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Fifty patients (mean ± SD age, 30 ± 12 years) undergoing BPTB ACL autograft reconstruction were randomized to the PRP (n = 27) or sham (n = 23) treatment. In either case, 10 mL of venous blood was drawn before the induction of anesthesia and either discarded (sham) or processed (PRP) for preparation of a PRP gel to be later mixed with donor site bone chips and inserted into the patellar defect. At 12 weeks, 6 months, 1 year, and 2 years after surgery, patients completed International Knee Documentation Committee (IKDC) forms and visual analog scale pain scores for activities of daily living and kneeling. Healing indices at the donor site were assessed by routine noncontrast magnetic resonance imaging (MRI) at 6 months. Mixed-model analysis of variance was used to assess the effect of PRP on patient symptoms and MRI indices of donor site healing, as measured by the width of the donor site defect.

RESULTS

Kneeling pain, pain with activities of daily living, and IKDC scores were not different between treatment groups at any of the time intervals ( P = .08-.83). Kneeling pain improved from 12 weeks to 6 months and from 1 to 2 years ( P < .05). IKDC scores improved substantially from 12 weeks to 6 months ( P < .001) and continued to improve to 2 years (PRP, 86 ± 19; sham, 89 ± 10). MRI indices of donor site healing were not different between treatment groups ( P = .53-.90).

CONCLUSION

Whether randomized to receive PRP in their patellar defect or not, patients continued to have similar levels of kneeling pain and patellar defect sizes after autograft BPTB ACL reconstruction. Registration: NCT01765712 ( ClinicalTrials.gov identifier).

Distal Clavicle Fracture Repair Using Cortical Button Fixation With Coracoclavicular Ligament Reconstruction

Management of distal clavicle fractures remains controversial. Various treatment options have been described including open reduction and internal fixation with hook plate fixation, tension band wiring, screw fixation, and distal locking plates. Many of these techniques are associated with a high perioperative complication rate. We describe a surgical technique that allows indirect fixation of distal clavicle fractures and reconstruction of the CC ligaments without the use of prominent hardware.

Fifth Metatarsal Jones Fractures in the Athlete

Fifth metatarsal fractures, otherwise known as "Jones" fractures, occur commonly in athletes and nonathletes alike. While recent occurrence in the popular elite athlete has increased public knowledge and interest in the fracture, this injury is common at all levels of sport. This review will focus on all three types of Jones fractures. The current standard for treatment is operative intervention with intramedullary screw fixation. Athletes typically report an acute episode of lateral foot pain, described as an ache. Radiographic imaging with multiple views of the weightbearing injured foot are needed to confirm diagnosis. If these images are inconclusive, further magnetic resonance imaging (MRI) or computed tomography (CT) is used. Nonoperative treatment is not commonly used as the sole treatment, except when following reinjury of a stable screw fixation. While screw selection is still controversial, operative treatment with intramedullary screw fixation is the standard approach. Technical tips on screw displacement are provided for Torg (types I, II, III) fractures, cavovarus foot fractures, recurrent fractures, revision surgery, occult fractures/high-grade stress reactions, and Jones' variants. Excellent clinical outcomes can be expected in 80% to 100% of patients when using the intramedullary screw fixation to "fit and fill" the medullary canal with threads across the fracture site. Most studies show the timing for return to sports with optimal healing to be seven to twelve weeks after fixation.

LEVEL OF EVIDENCE

Level V, expert opinion.

Deep Surgical Site Infections Following Pediatric Cervical Spine Surgery

OF BACKGROUND DATA

This is the first reported series looking specifically at factors associated with deep surgical site infections (SSI) following pediatric cervical spine surgery.

OBJECTIVE

To identify risk factors present in pediatric patients who are at risk for SSI following cervical spine surgery.

DESIGN

Level of evidence: level IV-retrospective case series.

INTRODUCTION

To date there are no studies regarding SSI in pediatric cervical spine surgery and thus no benchmark data or risk factors have been identified.

METHODS

Patients with acute deep SSIs occurring within 90 days of the index operation were identified. Patient and surgical characteristics were analyzed for possible predictors of SSI outcome using penalized likelihood logistic regression analysis. Characteristics analyzed included: age, diagnosis, comorbidity, levels fused, approach, implants used, allograft, halo, body mass index, revision, antibiotic dosing, and occipital plating.

RESULTS

A total of 112 patients were included in the study at a mean age of 12.5 years (2 to 18 y). Comorbidities were present in 51 (46%) patients, 15 patients had a documented connective tissue disorder (CTD). The mean number of levels fused was 3.7 (2 to 7) and mean number of screws was 4.4 (2 to 11). Allograft was used alone in 48 patients, occipital plating in 28 patients, and a halo in 39 patients. Deep SSI occurred in 3 patients: two of which had a CTD (1 Trisomy 21, 1 Ehlers-Danlos) and 1 patient with postradiation cervical kyphosis. All were gram-positive infections requiring return to operating room with prolonged IV antibiotics. All patients recovered and fused with spinal implant retention. The incidence of deep SSI was 2.7%. It was determined that a CTD was the only significant predictor of SSI. Subjects with a CTD had 12 times the odds of SSI [odds ratio=12 (1.5, 137.0); P=0.02].

CONCLUSIONS

In our series of pediatric patients the incidence of a deep SSI was 2.7%. The only predictor of SSI was the presence of a CTD.

Diffusion tensor imaging of the optic chiasm in patients with intra- or parasellar tumor using readout-segmented echo-planar

PURPOSE

To evaluate the impact of surgery on the optic pathway of patients with intra- or parasellar mass lesions, as evidenced by readout-segmented DTI.

MATERIALS AND METHODS

Twenty-four patients with intra- or parasellar mass lesions were included in the study. Readout-segmented DTI and T2WI were obtained before and after surgery. The ROIs were set on the optic chiasm as well as the anterior and posterior optic tracts. For each ROI, axial diffusivity (AD), radial diffusivity (RD), fractional anisotropy (FA), and ADC values were calculated. DTI parameters in preoperative studies of all patients were compared and related to the presence of tumor compression. In patients who underwent surgery, pre- and postoperative DTI parameters were compared. The correlation between DTI parameters and visual function was determined.

RESULTS

In the preoperative studies, the optic chiasm of patients with tumor compression showed significant lower AD and RD values. The optic chiasm of patients with visual field disorder showed significantly lower AD and RD values compared to patients without the disorder. There was a negative correlation with a trend toward significance between FA values and visual field disorder scores. The comparative analysis of patients in pre- and postoperative studies showed that the optic chiasm of patients with tumor compression presented a significant lower FA (0.41 versus 0.30, p=0.0068) and higher RD values after surgery.

CONCLUSIONS

DTI is a useful tool to assess the impact of surgery on the optic chiasm and nerve.

[Application of brain diffusion-weighted imaging performed using readout segmentation of long variable echo trains]

We report the preliminary use of the readout segmentation of long variable echo trains(RESOLVE)sequence, a novel magnetic resonance(MR)scanning technique based on a readout segmented echo planar imaging(EPI)strategy. RESOLVE enables high-resolution diffusion-weighted imaging(DWI)by minimizing susceptibility distortions and T2* blurring. The software for this sequence was provided by Siemens AG, Germany. Previously, we determined appropriate sequence parameters to obtain sufficiently high-resolution images through phantom studies. Then, we applied the sequence to some clinical cases with neurological disorders and analyzed the RESOLVE-DWI data with diffusion tensor imaging(DTI)techniques. In this article, we report clinical application of the RESOLVE sequence in two cases, one with cerebellar infarction and one with an intracranial epidermoid cyst. In both cases, RESOLVE-DWI clearly exposed structures that were obscured or severely distorted by artifacts on usual single-shot EPI-DWI. DTI analyses for RESOLVE-DWI data provided detailed information about fiber tracts and cranial nerves.

Modern trunnions are more flexible: a mechanical analysis of THA taper designs

BACKGROUND

There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in contemporary THAs. Although taper corrosion involves a complex interplay of many factors, a previous study suggested that a decrease in flexural rigidity of the femoral trunnion may be associated with an increased likelihood of corrosion at retrieval.

QUESTIONS/PURPOSES

By analyzing a large revision retrieval database of femoral stems released during a span of three decades, we asked: (1) how much does flexural rigidity vary among different taper designs; (2) what is the contribution of taper geometry alone to flexural rigidity of the femoral trunnion; and (3) how have flexural rigidity and taper length changed with time in this group of revised retrievals?

METHODS

A dual-center retrieval analysis of 85 modular femoral stems released between 1983 and 2012 was performed, and the flexural rigidity and length of the femoral trunnions were determined. These stems were implanted between 1991 and 2012 and retrieved at revision or removal surgery between 2004 and 2012. There were 10 different taper designs made from five different metal alloys from 16 manufacturers. Digital calipers were used to measure taper geometries by two independent observers.

RESULTS

Median flexural rigidity was 228 N-m(2); however, there was a wide range of values among the various stems spanning nearly an order of magnitude between the most flexible (80 N-m(2)) and most rigid (623 N-m(2)) trunnions, which was partly attributable to the taper geometry and to the material properties of the base alloy. There was a negative correlation between flexural rigidity and length of the trunnion and release date of the stem.

CONCLUSIONS

There is wide variability in flexural rigidity of various taper designs, with a trend toward trunnions becoming shorter and less rigid with time.

CLINICAL RELEVANCE

This temporal trend may partly explain why taper corrosion is being seen with increasing frequency in modern THAs.

Arthroscopic tenodesis of the long head of the biceps

The long head of the biceps (LHB) is commonly implicated in shoulder pathology due to its anatomic course and intimacy with the rotator cuff and superior labrum of the glenoid. Treatment of tendinosis of the LHB may be required secondary to partial thickness tears, instability/subluxation, associated rotator cuff tears, or SLAP (superior labrum, anterior to posterior) lesions. Treatment options include open or arthroscopic techniques for tenodesis vs tenotomy. Controversy exists in the orthopedic literature regarding the preferred procedure. The all-arthroscopic biceps tenodesis technique is a viable and reproducible option for treatment. This article provides a review of the all-arthroscopic biceps tenodesis technique using proximal interference screw fixation and its subsequent postoperative regimen. All-arthroscopic biceps tenodesis maintains elbow flexion and supination power, minimizes cosmetic deformities, and leads to less fatigue soreness after active flexion. Thus, arthroscopic biceps tenodesis should be offered and encouraged as a treatment option for younger, active patients.

Optimal management of ankle syndesmosis injuries

Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains), and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid) and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on controlling swelling and recovery from surgery. The protocols then progress to restoration of motion, early protected weight bearing, restoration of strength, and eventually a functional progression back to desired activities.

Scan time reduction for readout-segmented EPI using simultaneous multislice acceleration: Diffusion-weighted imaging at 3 and 7 Tesla

PURPOSE

Readout-segmented echo-planar imaging (rs-EPI) can provide high quality diffusion data because it is less prone to distortion and blurring artifacts than single-shot echo-planar imaging (ss-EPI), particularly at higher resolution and higher field. Readout segmentation allows shorter echo-spacing and echo train duration, resulting in reduced image distortion and blurring, respectively, in the phase-encoding direction. However, these benefits come at the expense of longer scan times because the segments are acquired in multiple repetitions times (TRs). This study shortened rs-EPI scan times by reducing the TR duration with simultaneous multislice acceleration.

METHODS

The blipped-CAIPI method for slice acceleration with reduced g-factor SNR loss was incorporated into the diffusion-weighted rs-EPI sequence. The rs- and ss-EPI sequences were compared at a range of resolutions at both 3 and 7 Tesla in terms of image fidelity and diffusion postprocessing results.

RESULTS

Slice-accelerated clinically useful trace-weighted images and tractography results are presented. Tractography analysis showed that the reduced artifacts in rs-EPI allowed better discrimination of tracts than ss-EPI.

CONCLUSION

Slice acceleration reduces rs-EPI scan times providing a practical alternative to diffusion-weighted ss-EPI with reduced distortion and high resolution. Magn Reson Med 74:136-149, 2015. © 2014 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

A comprehensive update on current fixation options for two-part proximal humerus fractures: a biomechanical investigation

BACKGROUND

Recent advancements in implant technology offer updated options for surgical management that have been rapidly adopted into clinical practice. The objective of this study is to biomechanically test and compare the current fixation options available for surgical fixation of two-part proximal humerus fractures and establish load to failure and stiffness values.

METHODS

Sixteen match-paired (32 total) fresh-frozen, cadaveric specimens were randomized to receive 1 of 4 fixation constructs following creation of an AO/OTA Type 11A3 (two-part) proximal humerus fractures. Fixation constructs tested consisted of 3.5 mm fixed angle plate (3.5-FAP), 4.5 mm fixed angle plate (4.5-FAP), humeral intramedullary nail (IMN), and a humeral intramedullary nail with a fixed angle blade (IMN-FAB). Specimen bone density was measured to ensure no adequate, non-osteoporotic bone. Constructs were tested for stiffness and ultimate load to failure and compared via one-way ANOVA analysis with subsequent post hoc Tukey HSD multiple group comparison statistical analysis.

RESULTS

The IMN-FAB construct was significantly stiffer than the 3.5-FAP construct (123.8 vs. 23.9, p<0.0001), the 4.5-FAP construct (123.8 vs. 33.3, p<0.0001) and the IMN construct (123.8 vs. 60.1, p=0.005). The IMN-FAB construct reported a significantly higher load to failure than the 3.5-FAB construct (4667.3 N vs. 1756.9 N, p<0.0001), and the 4.5-FAP construct (4667.3 N vs. 2829.4 N, p=0.019, Table 2). The IMN construct had a significantly higher load to failure than the 3.5-FAP construct (3946.8 vs. 1756.9, p=0.001, Table 2).

CONCLUSION

Biomechanical testing of modern fixation options for two-part proximal humerus fracture exhibited that the stiffest and highest load to failure construct was the IMN-FAB followed by the IMN, 3.5-FAP and then the 4.5-FAP constructs. However, prospective clinical trials with longer-term follow-up are required for definitive assessment of the ideal fixation construct for surgical management of two-part proximal humerus fractures.

Acute achilles tendon repair: strength outcomes after an acute bout of exercise in recreational athletes

BACKGROUND

This is the first study to evaluate the effect of an acute bout of exercise on strength evaluation after Achilles tendon (AT) rupture and repair.

METHODS

Forty patients sustained an acute AT injury and met inclusion criteria for this study. At a minimum of 12 months after operative repair, patients were measured for (1) calf circumference, (2) bilateral isokinetic strength on a Cybex dynamometer before and after 30 minutes of walking at 70% maximal exertion, and (3) subjective evaluation by AAOS lower limb core and foot and ankle modules. Follow-up occurred at a mean of 32.4 ± 20.7 (range, 12-80) months after surgery, and patients were on average 44.4 ± 8.6 (range, 20-62) years old. One-tailed Student's paired t tests analyzed significance for strength and fatigue between the involved and uninvolved ankle (P < .05).

RESULTS

The calf circumference of the involved ankle was significantly smaller than the uninvolved ankle by 1.9 cm, or 4.7%. Plantarflexion deficits of the involved ankle ranged from 12% to 18% for peak torque (P < .0001) and from 17% to 25% for work per repetition (P < .0001), but both ankles fatigued at equal proportions as measured after exercise. Dorsiflexion strength of the involved ankle increased 6% to 11% for peak torque (P = .070) and 1% to 25% for peak work (P = .386). Reported AAOS lower limb core and foot and ankle scores averaged 99.8 and 96.0, respectively.

CONCLUSION

After an AT rupture with repair, patients had less plantarflexion strength, and equal dorsiflexion strength in the operative leg compared to the uninvolved, normal leg. However, subjective results indicated near normal pain and function despite mild plantarflexion strength deficits. Dorsiflexion strength was normal after repair and remained normal even after an acute bout of exercise. Plantarflexion strength ratios postexercise remained similar to pre-exercise after acute exercise bouts. Athletes reported a "flat tire" feeling while running, which suggests a probable gait adjustment as cause for long-term plantarflexion strength deficits.

LEVEL OF EVIDENCE

Level III, cohort study.

High-resolution diffusion-weighted imaging for the separation of benign from malignant BI-RADS 4/5 lesions found on breast MRI at 3T

PURPOSE

To determine whether readout-segmented echo-planar diffusion imaging (RESOLVE) improves separation of malignant versus benign lesions compared to standard single-shot echo-planar imaging (ss-EPI) on BI-RADS 4/5 lesions detected on breast magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Consecutive 3T breast MRI studies with BI-RADS 4/5 designation and subsequent biopsy or benign mastectomy were retrospectively identified. Freehand regions of interest (ROIs) were drawn on lesions and also on normal background fibroglandular tissue for comparison. Lesion-to-background contrast was evaluated by normalizing signal intensity of the lesion ROI by the normal background tissue ROI at b = 800. Statistical analysis used the Mann-Whitney/Wilcoxon rank-sum test for unpaired and Wilcoxon signed-rank for paired comparisons.

RESULTS

Of 38 lesions in 32 patients, 10 were malignant. Lesion-to-background contrast was higher on RESOLVE than ss-EPI (1.80 ± 0.71 vs. 1.62 ± 0.63, P = 0.03). Mean apparent diffusion coefficient (ADC) was the same or lower on RESOLVE than ss-EPI, and this effect was largest in malignant lesions (RESOLVE 0.90 ± 0.13; ss-EPI 1.00 ± 0.13; median difference -0.10 (95% confidence interval [CI]: -0.17, -0.02) × 10(-3) mm(2) /sec; P = 0.014). By either diffusion method, there was a statistically significant difference between benign and malignant mean ADC (P < 0.001).

CONCLUSION

Increased lesion-to-background contrast and improved separation of benign from malignant lesions by RESOLVE compared to standard diffusion suggests that RESOLVE may show promise as an adjunct to clinical breast MRI.

Effect of B-value in revealing postinfarct myocardial microstructural remodeling using MR diffusion tensor imaging

Nonmonoexponential diffusion behavior has been previously reported to exist in some biological tissues, making quantification of diffusion tensor imaging (DTI) indices dependent on diffusion sensitivity of b-value. This study aims to investigate the effect of b-value in revealing postinfarct myocardial microstructural remodeling in ex vivo hearts. DTI scans were performed on heart samples 1, 3, 5, and 7 days after infarction induction as well as intact controls with b-values of 500 to 2500s/mm(2). DTI indices, including fractional anisotropy (FA), and mean and directional diffusivities, were measured in infarct, adjacent and remote regions with zero and each non-zero b-values respectively using conventional DTI analysis. Experimental results showed that these DTI indices decreased gradually with b-values in all regions and groups. Optimal b-values were found to vary with targeted DTI indices, and could strengthen DTI ability in revealing myocardium degradation with using conventional DTI approach. Specifically, FA showed the most sensitive detection of fiber integrity degradation at moderate b-values (≈1500 to 2000s/mm(2)), and the greatest ability of mean and directional diffusivities in monitoring diffusivity alteration occurred at relatively small b-values (≤1500s/mm(2)) during the necrotic and fibrotic phases. These findings may provide useful information for DTI protocol parameter optimization in assessing heart microstructures at other pathological or in vivo states in the future.

Abstract P4-01-10: High-resolution diffusion weighted imaging for the separation of benign from malignant BI-RADS 4/5 lesions found on breast MRI at 3 Tesla

Diffusion weighted imaging (DWI) has shown potential for separating malignant from benign lesions on breast MRI, theoretically improving the specificity of the breast MRI exam. However, standard DWI is hampered by multiple factors in the breast which limit utility in clinical practice. A readout segmented diffusion technique (RESOLVE)(1) permits the use of extremely short echo spacing and resamples uncorrectable data using a real-time navigator, reducing image distortion and potentially providing more accurate apparent diffusion coefficient (ADC) within lesions. In order to study the potentially utility of this method against standard diffusion, we compared ADC values from retrospectively-identified BI-RADS 4/5 (suspicious) lesions with both standard single shot-spin echo EPI (ss-EPI) and RESOLVE diffusion at 3 Tesla over a 10-month period. All patients subsequently went to image-directed biopsy.

The imaging parameters were as follows: TR/TE=7500-10000/60 ms (ss-EPI) and 8000–12000/64 ms (RESOLVE), averages=8 (ss-EPI) and 1 (RESOLVE), readout segmentation factor 5 with echo spacing of 0.3 ms (RESOLVE), slices = 47–50, b-values 0, 800, resolution = 1.8×1.8×2.4 mm3, imaging times of approximately 5 minutes for both techniques. Freehand ROI's were drawn on each suspicious lesion based on b=800 maps in close reference to the post-contrast T1 series by a board-certified radiologist who was blinded to final pathology and sequence. Similar ROI's were drawn in normal tissue as a control. For each lesion, mean ADC values and signal intensities at b=800 were recorded. ADC values were averaged by technique and pathologic outcome (benign or malignant). Signal intensity was normalized by dividing mean signal intensity of the lesion ROI by that of the control. Significance was determined using Wilcoxon rank-sum test for ADC, and paired t-test for signal intensity measures.

Of the final cohort of 38 lesions in 31 patients, 9 were malignant and the remainder were benign. Two lesions were no longer present at breast MRI biopsy, and hence deemed benign. The lesion-to-background signal intensity on diffusion was higher (p = 0.05) on RESOLVE (1.9±0.1) compared to standard diffusion (1.7±0.1). Statistically significant differences between benign and malignant lesion were observed for mean ADC obtained by both methods (Table 1; p &lt; 0.001). Between sequences, there was excellent agreement between RESOLVE and standard EPI for control values obtained from normal tissue, and for mean ADC values of benign lesions. Among malignant lesions, however, there was a statistically significant decrease in mean ADC values measured by RESOLVE (p = 0.05), which effectively widened the separation between benign and malignant lesions.

Our results suggest improved separation of benign from malignant lesions by RESOLVE compared to standard diffusion, as well as increased lesion-to-background contrast, suggesting that this diffusion method has particular promise as an adjunct to dynamic-contrast-enhanced breast MRI.

(1) Porter DA, et al MRM 2009; 62:468–75.

Drop metastases to the pediatric spine revealed with diffusion-weighted MR imaging

Identifying drop metastases to the spine from pediatric brain tumors is crucial to treatment and prognosis. MRI is currently the gold standard for identifying drop metastases, more sensitive than CSF cytology, but imaging is not uncommonly inconclusive. Although diffusion-weighted imaging (DWI) of the brain is very useful in the evaluation of hypercellular tumors, DWI of the spine has not been clinically useful in children because of susceptibility artifacts and lack of spatial resolution. A new technique, readout-segmented echo planar imaging (EPI), has improved these images, allowing for identification of hypercellular drop metastases. We report a case that illustrates the utility of spine DWI in the detection of metastatic disease in children with primary central nervous system (CNS) tumors. This case suggests that DWI of the spine with readout-segmented EPI should be included in the evaluation for drop metastases.

Diffusion imaging in humans at 7T using readout-segmented EPI and GRAPPA

Anatomical MRI studies at 7T have demonstrated the ability to provide high-quality images of human tissue in vivo. However, diffusion-weighted imaging at 7T is limited by the increased level of artifact associated with standard, single-shot, echo-planar imaging, even when parallel imaging techniques such as generalized autocalibrating partially parallel acquisitions (GRAPPA) are used to reduce the effective echo spacing. Readout-segmented echo-planar imaging in conjunction with parallel imaging has the potential to reduce these artifacts by allowing a further reduction in effective echo spacing during the echo-planar imaging readout. This study demonstrates that this approach does indeed provide a substantial improvement in image quality by reducing image blurring and susceptibility-based distortions, as well as by allowing the acquisition of diffusion-weighted images with a high spatial resolution. A preliminary application of the technique to high-resolution diffusion tensor imaging provided a high level of neuroanatomical detail, which should prove valuable in a wide range of applications.

High resolution diffusion-weighted imaging using readout-segmented echo-planar imaging, parallel imaging and a two-dimensional navigator-based reacquisition

Single-shot echo-planar imaging (EPI) is well established as the method of choice for clinical, diffusion-weighted imaging with MRI because of its low sensitivity to the motion-induced phase errors that occur during diffusion sensitization of the MR signal. However, the method is prone to artifacts due to susceptibility changes at tissue interfaces and has a limited spatial resolution. The introduction of parallel imaging techniques, such as GRAPPA (GeneRalized Autocalibrating Partially Parallel Acquisitions), has reduced these problems, but there are still significant limitations, particularly at higher field strengths, such as 3 Tesla (T), which are increasingly being used for routine clinical imaging. This study describes how the combination of readout-segmented EPI and parallel imaging can be used to address these issues by generating high-resolution, diffusion-weighted images at 1.5T and 3T with a significant reduction in susceptibility artifact compared with the single-shot case. The technique uses data from a 2D navigator acquisition to perform a nonlinear phase correction and to control the real-time reacquisition of unusable data that cannot be corrected. Measurements on healthy volunteers demonstrate that this approach provides a robust correction for motion-induced phase artifact and allows scan times that are suitable for routine clinical application.

Comparison of 4.5- and 5.5-mm cannulated stainless steel screws for fifth metatarsal Jones fracture fixation

BACKGROUND

Complications including delayed and nonunions, and extensive time nonweightbearing with conservative treatment of fifth metatarsal Jones fractures, have led authors to recommend surgical fixation for this fracture in athletes who wish to return to activity quickly. The optimal surgical procedure, however, has not been determined. The purpose of this study was to evaluate the effectiveness of 5.5-mm cannulated screw fixation for fifth metatarsal stress fractures in athletes and compare them to an earlier cohort treated with a 4.5-mm screw.

MATERIALS AND METHODS

Twenty athletes were treated surgically with a 5.5-mm cannulated screw and postoperatively wore a removable walking boot, applied cold compression, initiated immediate range of motion, and used crutches for 1 week. Fractures were evaluated for clinical and radiographic healing. These findings were compared to a group that used 4.5-mm screws.

RESULTS

Average radiographic healing was 96.7% and all fractures healed clinically. Athletes returned to sports in an average of 9.3 weeks. There were three re-injuries that were treated with 2 weeks in a walking boot. No patients have required screw removal or have experienced pain at the hardware site, besides the three re-injuries. When compared to the earlier study, no differences were found. However, there were no re-fractures in the 4.5-mm study, but there were three bent screws.

CONCLUSION

The current study demonstrates the clinical effectiveness of the 5.5-mm screw. However, with the numbers available, we were unable to demonstrate significant improvement over the 4.5-mm screw and thus cannot conclude that a larger screw is more effective.

Evaluation and treatment of ankle syndesmosis injuries

Athletes sustain ankle syndesmosis injuries far less frequently than they do lateral ankle sprains; however, syndesmosis injuries are more challenging to detect and treat. Grade II injuries, which are occultly unstable, may be overlooked or treated too conservatively (nonsurgically), leading to latent diastasis, chronic instability, further injury, arthritic changes, chronic pain, osteochondral lesions, and other sequelae. Surgical intervention for chronic syndesmosis injuries produces mixed results and creates an uncertain future for athletes who desire to return to their sport. Optimal treatment starts with a comprehensive evaluation that includes a thorough physical examination as well as imaging studies to evaluate for instability (medial clear space widening and syndesmosis disruption). All acute unstable syndesmosis injuries (grades II and III) should be treated with surgery, which can include repair of the deltoid ligament with open reduction and internal fixation of the syndesmosis. Isolated deltoid sprains also are often repaired surgically in athletes. This more aggressive treatment helps avoid the chronic pain and instability and osteochondral abnormalities associated with chronic injury.

Functional outcome after operative treatment for ankle fractures in young athletes: a retrospective case series

BACKGROUND

No reports describe the outcome for distal fibula and tibia fractures in athletes, although 10 to 15% of all athletic injuries occur around the ankle joint.

MATERIALS AND METHODS

Forty-seven competitive or recreational athletes with ankle fractures underwent open reduction and internal fixation (ORIF). Thirty-six met the inclusion criteria, of which 27 returned for clinical and radiographic exams and also completed validated surveys and a subjective questionnaire.

RESULTS

Nineteen of the 27 were male. The average age of all patients was 18.1 +/- 5.9 years. The final evaluations occurred 12 months to 3.7 years after surgery. Injuries occurred in 13 different sports, of which football had the most (n = 10). Bimalleolar fractures were the most prevalent (n = 10) followed by isolated lateral malleolar fractures (n = 6), syndesmosis injury (n = 4), Salter-Harris (n = 4), medial malleolar fracture (n = 2) and pilon fracture (n = 1). The patients with isolated lateral malleolar fractures returned to competition soonest (6.8 +/- 2.4 weeks) while patients with isolated medial malleolus fractures took the longest to return at a mean of 17.0 +/- 9.9 weeks. Scores for function and pain on the Lower Limb Core Module and for pain on the Foot and Ankle module were all greater than 90.

CONCLUSION

Athletes who undergo ORIF followed by early motion and early weightbearing are able to return to their pre-injury level of competition within 2 to 4 months with minimal functional morbidity or pain.

Reconstruction as a source of artifact in non-gated single-shot diffusion-weighted EPI

A controversy has existed over the requirement to cardiac gate diffusion-weighted MRI acquisitions of the brain. Conventional wisdom suggests gating to be a necessary requirement to allow acquisition of accurate data, but recent applications find gating not necessary. The signal-to-noise and acquisition duration of these two approaches can be quite different; thus, this difference in methodology is important. This is particularly relevant when performing quantitative work such as diffusion tensor imaging. Here, the convention to gate is explained as being due to the historical use of low spatial resolution and more recently to the use of different reconstruction approaches. It is demonstrated that the Margosian reconstruction approach only yields high quality results when used in a gated fashion. Zero padding of the acquisition matrix provides an alternative reconstruction method that is not found to accentuate the artifacts that are due to pulsatile motion in the diffusion-weighted acquisition and thus do not require a gated acquisition. The relative merits of each reconstruction approach are discussed, including estimates of the relative signal-to-noise ratio and resolution benefits. It is concluded that both gated methods and non-gated methods can each provide high quality results with appropriate reconstruction methods.

Fifth metatarsal Jones fracture fixation with a 4.5-mm cannulated stainless steel screw in the competitive and recreational athlete: a clinical and radiographic evaluation

BACKGROUND

Fifth metatarsal Jones fractures are common in the athletic population. Optimal screw selection for operative treatment has not been determined.

HYPOTHESIS

A 4.5-mm cannulated screw used for fixation of the fifth metatarsal Jones fractures in athletes is an effective treatment approach.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors studied 23 consecutive athletes (24 feet) who were treated surgically with a 4.5-mm cannulated screw for fifth metatarsal fractures (Jones fracture) with clinical and radiographic assessments.

RESULTS

There have been no refractures to date. Clinical healing was 100%. The mean percentage healing as shown on radiographs was 98.9%, with a range of 90% to 100%. All athletes returned to sport at a mean time of 7.5 weeks (range, 10 days to 12 weeks). Two athletes experienced a "reinjury" without need for operative treatment. All athletes were recommended to wear orthoses until their competitive careers were completed.

CONCLUSION

Fixation with a stainless steel 4.5-mm cannulated screw gives 100% clinical healing and near-100% healing as shown on radiographs.

CLINICAL RELEVANCE

The 4.5-mm cannulated screws can yield reliable and effective healing as evidenced by clinical assessment and radiographs of fifth metatarsal Jones fractures in athletes.

Potential risk of rerupture in primary achilles tendon repair in athletes younger than 30 years of age

BACKGROUND

Complete Achilles tendon ruptures are found more often in athletes who participate in sports involving explosive acceleration or maximal effort. In most studies, the consensus for athletes is surgery. This form of treatment has been shown to exhibit the best functional performance with a lower rerupture rate.

HYPOTHESIS

Achilles tendon ruptures in a young population (<30 years) have a higher rerupture rate than similar injuries in an older age group (31-50 years), in which the injury is more common.

STUDY DESIGN

Cohort study; Level of evidence, 4.

METHODS

Retrospective study was carried out by chart review. Magnetic resonance images were obtained comparing appearance of repair in young and old patients at 8 to 12 weeks after operation.

RESULTS

There were a total of 4 reruptures in the 89 Achilles tendon repairs. This was an overall rerupture rate of 4.5%, which was consistent with the literature. When the reruptures were critically analyzed, it was noted that the 4 reruptures of the repaired tendon occurred in a young population. Of the 89, there was a subgroup of athletes (n=24) who were 30 years of age or younger at the time of injury. The incidence of rerupture for these individuals was 16.6%. In the remaining athletes (n=65) older than 30 years, the incidence of rerupture was zero. There were no significant differences (P < or =.05) in all parameters measured (average days in a boot, average days to active range of motion, average time to full weight-bearing, average days to bike or use a stair climbing machine, average return to sports) between age groups except in the time from injury to surgery (7.1 days, for athletes < or =30 years vs 2.65 days for athletes >31 years).

CONCLUSIONS

The results of Achilles tendon repair with an early weightbearing and an early range of motion rehabilitation program are good. However, caution may need to be taken in the younger athlete (< or =30 years) during rehabilitation.

CLINICAL RELEVANCE

Although the authors recommend aggressive rehabilitation for Achilles tendon repairs, caution should be observed in the younger athlete.

Arthrogenic muscle response to a simulated ankle joint effusion

BACKGROUND

Arthrogenic muscle inhibition (AMI) is a continuing reflex reaction of the musculature surrounding a joint after distension or damage to the structures of that joint. This phenomenon has been well documented after knee joint injury and has been generalised to occur at other joints of the human body, yet minimal research has been conducted in this regard. The response of the muscles crossing the ankle/foot complex after ankle injury and effusion is not well understood. AMI may occur after an ankle sprain contributing to residual dysfunction.

OBJECTIVE

To determine if AMI is present in the soleus, peroneus longus, and tibialis anterior musculature after a simulated ankle joint effusion.

METHODS

Eight neurologically sound volunteers (mean (SD) age 23 (4) years, height 171 (6) cm, mass 73 (10) kg) participated. Maximum H-reflex and maximum M-wave measurements were collected using surface electromyography after delivery of a percutaneous stimulus to the sciatic nerve before its bifurcation into the common peroneal and posterior tibial nerves.

RESULTS

The H-reflex and M-wave measurements in all muscles increased (p< or =0.05) after the simulated ankle joint effusion.

CONCLUSIONS

Simulated ankle joint effusion results in facilitation of the soleus, peroneus longus, and tibialis anterior motoneurone pools. This may occur to stabilise the foot/ankle complex in order to maintain posture and/or locomotion.

HIN-1, a putative cytokine highly expressed in normal but not cancerous mammary epithelial cells

To identify molecular alterations implicated in the initiating steps of breast tumorogenesis, we compared the gene expression profiles of normal and ductal carcinoma in situ (DCIS) mammary epithelial cells by using serial analysis of gene expression (SAGE). Through the pair-wise comparison of normal and DCIS SAGE libraries, we identified several differentially expressed genes. Here, we report the characterization of one of these genes, HIN-1 (high in normal-1). HIN-1 expression is significantly down regulated in 94% of human breast carcinomas and in 95% of preinvasive lesions, such as ductal and lobular carcinoma in situ. This decrease in HIN-1 expression is accompanied by hypermethylation of its promoter in the majority of breast cancer cell lines (>90%) and primary tumors (74%). HIN-1 is a putative cytokine with no significant homology to known proteins. Reintroduction of HIN-1 into breast cancer cells inhibits cell growth. These results indicate that HIN-1 is a candidate tumor suppressor gene that is inactivated at high frequency in the earliest stages of breast tumorogenesis.