Acute scaphoid fractures

Scaphoid Fat Stripe Sign: Is It a Reliable Radiological Sign of Scaphoid Fracture in Children?

OBJECTIVES

The scaphoid fat pad stripe (SFS) is a radiological sign first described in 1975 as a line of relative lucency lying parallel to the lateral border of the scaphoid, with slight convexity toward it, and it is optimally demonstrated on postero-anterior and oblique views with ulnar deviation of the carpus. The obliteration or displacement of this line is commonly present in acute fractures of the scaphoid, radial styloid process, and proximal first metacarpus. The aim of this observational study is to investigate the supportive value of the fat stripe sign (SFS) in the diagnosis of scaphoid fractures in the pediatric population.

METHODS

This is a monocentric, retrospective study of all patients referred to the Pediatric Traumatology Unit of a tertiary hospital from the Emergency Department with clinical suspicion of scaphoid fracture without visible fracture in the initial X-ray. Radiological reports for CT and MRIs were recorded, and the initial X-rays were blindly reviewed by a pediatric orthopedic fellowship-accredited surgeon for the presence of an abnormal scaphoid fat pad stripe sign and the presence of a fracture line in the initial X-rays.

RESULTS

The results of the blind interpretation of the initial X-rays for the fat stripe sign showed 86% sensitivity and 58% specificity, with the negative predictive value reaching 92%.

CONCLUSIONS

The scaphoid fat stripe sign can be used as an adjacent in the diagnosis of an occult scaphoid fracture in children or adolescents. Its high negative predictive value, if confirmed in larger studies, can be an element used to exclude scaphoid fracture and consequently avoid unnecessary immobilizations and health costs.

Scaphoid waist fractures fixation with staple. Retrospective study of a not widespread procedure

INTRODUCTION

In carpal scaphoid fractures, the surgical treatment with screw is considered the gold standard; shape memory staple however presents substantial advantages. The authors report a study on unstable fractures of the scaphoid waist (type B1, B2, B5, according to Herbert classification) treated with shape memory staple on a large sample of patients, with the aim to confirm the usefulness of this method, the quality of reduction and fixation, the functional results, the time of union and the possible complications.

MATERIALS AND METHODS

A retrospective analysis of 131 patients with scaphoid waist fractures with minimum follow-up 1 year was performed. Staples were used in all cases; technical details are discussed. Outcome measures were: postoperative pain, flexion-extension wrist range, hand grip strength, radiographic consolidation, work absence. Herbert and Fisher Grading System was used to assess subjective, objective and radiographic results.

RESULTS

Consolidation was achieved in all cases of primary fractures (0-30 days) within three months after surgery, and within eight months in all but two cases of delayed unions (operated within 6 months of the injury). Pain was absent at follow-up in 79% of cases, never severe or unbearable, the average flexion-extension range achieved was 112°. Handgrip strength values were comparable to those of contralateral wrist in 75% of cases. Mean time lost at work was 7.4 weeks. No algo-distrophy or malunion were observed. Discussion CONCLUSIONS: Scaphoid waist fractures' treatment with shape memory staple should be considered as an excellent alternative to screw fixation.

Scapholunate Ligament Injury and the Effect of Scaphoid Lengthening

Objective  We hypothesized that lengthening the scaphoid in a model of scapholunate ligament injury (SLI) will result in correction of radiographic markers of dorsal intercalated segment instability (DISI) deformity. Materials and Methods  An SLI with DISI deformity was created by sectioning the SL ligament, the palmar radiocarpal ligaments, and scapho-trapezio-trapezoid ligaments of a cadaveric upper extremity ( n  = 5). The wrist was radiographed in both anteroposterior and lateral planes to confirm creation of SLI and DISI. The scaphoid was then osteotomized at its waist. A series of grafts (1-8 mm) were then placed at the osteotomy site. Radiographs were completed at each length. The main outcome measures were scapholunate interval (SL, mm), scapholunate angle (SLA, degrees), and radiolunate angle (RLA, degrees). These values, measured following the insertion of varying graft lengths, were compared with baseline measurements taken "post-injury" status. Results  The ability to create an SLI with DISI was confirmed in the postinjury group with a statistically significant change in RLA, SLA, and SL compared with preinjury. With osteotomy and progressive insertion of spacers, the values improved into the accepted normal ranges for RLA (6 mm) and SLA (4 mm) with scaphoid lengthening. Conclusions  In this cadaveric model of SL injury, radiographic markers of DISI were returned to within normal ranges with scaphoid osteotomy and lengthening. Clinical Relevance  The results of this study add insight into wrist kinematics in our injury model and may represent a potential future direction for surgical treatment of SLI.

Surgical versus nonsurgical treatment for scaphoid waist fracture with slight or no displacement: A meta-analysis and systematic review

BACKGROUND

Surgical or nonsurgical treatment for scaphoid waist fracture with slight or no displacement is still controversial. This study compared the efficacy of the 2 methods through meta-analysis to provide a reference for the choice of clinical treatment options.

METHODS

Two individuals independently searched for relevant RCTs and cohort studies from PubMed (1946-February 2018), Embase (1946-February 2018), and Cochrane library (1997-February 2018). After quality assessment and data extraction, Stata 14 software was used for combining the effect size, testing heterogeneity, and studying bias. GRADEpro was used to rate the level of evidence.

RESULTS

Ten RCTs and 4 cohort studies with 765 patients were included. No statistical difference in satisfaction, pain, and Disability of the Arm, Shoulder, and Hand score was found after surgical and nonsurgical treatments. Compared with nonsurgical treatment, surgical treatment shortened the time to union (SMD = -5.01, 95% CI: -7.47 to -2.58, P = .000), decreased the convalescence (SMD = -2.09, 95% CI: -3.08 to -1.11, P = .000), and reduced the incidence of nonunion (RR = 0.47, 95% CI: 0.24-0.90), P = .023). Subgroup analyses showed that the percutaneous fixation treatment can shorten the time to union [SMD = -1.82, 95%CI (-2.22 to -1.42), P = = .000] and the convalescence (SMD = -4.26, 95%CI: -6.16 to -2.35, P = = .054), and open reduction fixation treatment can reduce the incidence of nonunion (RR = 0.20, 95%CI: 0.06-0.69, P = = .01).

CONCLUSION

For scaphoid waist fractures with slight or no displacement, there was no statistical difference in patient satisfaction, pain, and The Disability of the Arm, Shoulder, and Hand scores between surgical treatment and nonsurgical treatment. Closed surgical treatment can shorten the time to union and convalescence, and open reduction can reduce the incidence of nonunion. On the basis of this conclusion, chief physicians can consider which treatment to use according to the patient's clinical situation and their subjective intention.

Interobserver Variability of the Diagnosis of Scaphoid Proximal Pole Fractures

Purpose  Fractures of the proximal pole of the scaphoid are prone to adverse outcomes such as nonunion and avascular necrosis. Distinction of scaphoid proximal pole fractures from waist fractures is important for management but it is unclear if the distinction is reliable. Methods  A consecutive series of 29 scaphoid fractures from one tertiary hospital was collected consisting of 5 scaphoid proximal pole and 24 scaphoid waist fractures. Fifty-seven members of the Science of Variation Group (SOVG) were randomized to diagnose fracture location and displacement by using radiographs alone or radiographs and a computed tomography (CT) scan. Results  Observers reviewing radiographs alone and observers reviewing radiographs and CT scans both had substantial agreement on fracture location (κ = 0.82 and κ = 0.80, respectively; p  = 0.54). Both groups had only fair agreement on fracture displacement (κ = 0.28 and κ = 0.35, respectively; p  = 0.029). Conclusion  Proximal pole fractures are sufficiently distinct from proximal waist fractures that CT does not improve reliability of diagnosis. Level of Evidence  Level IV interobserver reliability case-control study.

Micro Screw Fixation for Small Proximal Pole Scaphoid Fractures with Distal Radius Bone Graft

Background  Achieving adequate fixation and healing of small proximal pole acute scaphoid fractures can be surgically challenging due to both fragment size and tenuous vascularity. Purpose  The purpose of this study was to demonstrate that this injury can be managed successfully with osteosynthesis using a "micro" small diameter compression screw with distal radius bone graft with leading and trailing screw threads less than 2.8 mm. Patients and Methods  Patients with proximal pole scaphoid fragments comprising less than 20% of the entire scaphoid were included. Fixation was accomplished from a dorsal approach with a micro headless compression screw and distal radius bone graft. Six patients were included. Average follow-up was 44 months (range, 11-92). Results  Mean proximal pole fragment size was 14% (range, 9-18%) of the entire scaphoid. The mean immobilization time was 6 weeks, time-to-union of 6 weeks, and final flexion/extension arc of 88°/87°. All patients had a successful union, and no patient had deterioration in range of motion, avascular necrosis, or fragmentation of the proximal pole. Conclusion  Small diameter screws with a maximal thread diameter of ≤ 2.8 mm can be used to fix the union of proximal pole acute scaphoid fractures comprising less than 20% of the total area with good success. Level of Evidence  Therapeutic case series, Level IV.

Proximal Pole Scaphoid Nonunion Reconstruction With 1,2 Intercompartmental Supraretinacular Artery Vascularized Graft and Compression Screw Fixation

PURPOSE

To review the incidence of union of patients with proximal pole scaphoid fracture nonunions treated using a 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized graft and a small compression screw.

METHODS

This is a retrospective case series of 12 patients. Calculations of the size of the proximal pole fragment relative to the total scaphoid were performed using posteroanterior view scaphoid radiographs with the wrist in ulnar deviation and flat on the cassette. Analyses were repeated 3 times per subject, and the average ratio of proximal pole fragment relative to the entire scaphoid was calculated. We reviewed medical records, radiographs, and computed tomography (CT) scans of these 12 patients. The CT scans that were performed after an average of 12 weeks were ultimately used to confirm union of the scaphoid fractures. One patient was unable to have a CT so was excluded from the final calculation.

RESULTS

All 11 (100%) scaphoid fractures that were assessed by CT were found to be healed at the 12-week assessment point. The mean proximal pole fragment size was 18% (range, 7%-27%) of the entire scaphoid.

CONCLUSIONS

The 1,2 ICSRA vascularized graft and compression screw was an effective treatment for patients with proximal pole scaphoid fractures.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Conjoint Analysis of Treatment Preferences for Nondisplaced Scaphoid Fractures

PURPOSE

We used conjoint analysis to assess the relative importance of factors that influence a patient's decision between surgical or nonsurgical management of a nondisplaced scaphoid fracture. Our hypothesis was that out-of-pocket costs will have a greater influence on decision making than the time spent in a cast or brace, degree of soreness, or the risk of treatment failure.

METHODS

Two-hundred and fifty participants were recruited using Amazon Mechanical Turk and asked to assume that they had experienced a nondisplaced scaphoid waist fracture. They then indicated their relative preferences among 13 pairs of alternatives with variations in the following attributes: time in a cast, time in a brace, duration of ongoing soreness, risk of treatment failure (by which we meant scaphoid nonunion), out-of-pocket costs based on estimates of direct costs ($500-2,500), and apprehension about surgery. A conjoint analysis was used to determine the relative importance of these factors when choosing between surgical or nonsurgical management.

RESULTS

The factor with the greatest influence on treatment choice was the cost of the procedure. After assessing the respondent's apprehension to undergo surgery, a sensitivity analysis showed the proportion of respondents who would choose surgery given different outcomes. To make the predicted share of those who are "not worried" about surgery equal to those who are "somewhat worried" or "a little worried" would require that the cost of surgery increase by $2,700. In addition, 2 weeks in a cast, 3 weeks in a brace, 2 months of soreness, or a 2% increase in the risk of fracture nonunion generates the same surgical choice probability as a $2,000 increase in the out-of-pocket cost of surgery.

CONCLUSIONS

As conceptualized in this conjoint analysis, out-of-pocket costs and apprehension about surgery seem to have a greater impact on a decision for surgery than the time spent in a brace or cast and the risk of treatment failure.

TYPE OF STUDY/LEVEL OF EVIDENCE

Economic and decision analysis III.

The Scaphoid Staple: A Systematic Review

BACKGROUND

The purpose of this systematic review is to analyze the indications, outcomes, and complications of scaphoid fixation with a staple.

METHODS

The literature was reviewed for all cases of the scaphoid staple. Five articles including 188 patients, of 77 primary scaphoid fractures and 111 other indications that included delayed union, nonunion, and avascular necrosis, were reviewed. Demographic data, outcomes, and complications were recorded.

RESULTS

The union rate of the scaphoid staple is 94.7%, and 95.7% of patients return to work after an average of 9.8 weeks after a 4.7-week period of immobilization. The complication rate was 9.0%, and 7.5% required hardware removal. Clinical and radiographic healing was higher in primary fractures as compared with other indications. Other indications, as compared with primary fracture, had a higher rate of hardware removal.

CONCLUSIONS

For all indications, the scaphoid staple has a high union rate and a low complication rate. In the authors' experience, the procedure is fast, not technically challenging, and may be considered for primary fracture, delayed union, nonunion, and avascular necrosis of the scaphoid.

Anatomic Locking Plate Fixation for Scaphoid Nonunion

Nonunion can occur relatively frequently after scaphoid fracture and appears to be associated with severity of injury. There have been a number of techniques described for bone grafting with or without screw fixation to facilitate fracture healing. However, even with operative fixation of scaphoid fractures with bone grafting nonunion or malunion rates of 5 to 10 percent are still reported. This is the first report of an anatomic locking plate for scaphoid fracture repair in a 25-year-old right hand dominant healthy male.

Claims-based Identification Methods and the Cost of Fall-related Injuries Among US Older Adults

OBJECTIVES

Compare expenditures of fall-related injuries (FRIs) using several methods to identify FRIs in administrative claims data.

RESEARCH DESIGN

Using 2007-2009 Medicare claims and 2008 Health and Retirement Survey data, FRIs were identified using external-cause-of-injury (e-codes 880/881/882/884/885/888) only, e-codes plus a broad set of primary diagnosis codes, and a newer approach using e-codes and diagnostic and procedural codes. Linear regression models adjusted for sociodemographic, health, and geographic characteristics were used to estimate per-FRI, service component, patient cost share, expenditures by type of initial FRI treatment (inpatient, emergency department only, outpatient), and total annual FRI-related Medicare expenditures.

SUBJECTS

The analysis included 5497 community-dwelling adults ≥65 (228 FRI, 5269 non-FRI individuals) with continuous Medicare coverage and alive during the 24-month study.

RESULTS

The 3 FRI identification methods produced differing distributions of index FRI type and varying estimated expenditures: $12,171 [95% confidence interval (CI), $4662-$19,680], $5648 (95% CI, $3819-$7476), and $9388 (95% CI, $5969-$12,808). In all models, most spending occurred in hospital, outpatient, and skilled nursing facility (SNF) settings, but greater proportions of SNF and outpatient spending were observed with commonly used FRI identification methods. Patient cost-sharing was estimated at $691-$1900 across the 3 methods. Inpatient-treated index FRIs were more expensive than emergency department and outpatient-treated FRIs across all methods, but were substantially higher when identifying FRI using only e-codes. Estimated total FRI-related Medicare expenditures were highly variable across methods.

CONCLUSIONS

FRIs are costly, with implications for Medicare and its beneficiaries. However, expenditure estimates vary considerably based on the method used to identify FRIs.

Accuracy of enhanced and unenhanced MRI in diagnosing scaphoid proximal pole avascular necrosis and predicting surgical outcome

PURPOSE

Determine the sensitivity, specificity and accuracy of unenhanced and enhanced MRI in diagnosing scaphoid proximal pole (PP) avascular necrosis (AVN) and correlate whether MRI can help guide the selection of a vascularized or nonvascularized bone graft.

METHODS

The study was approved by the IRB. Two MSK radiologists independently performed a retrospective review of unenhanced and enhanced MRIs from 18 patients (16 males, 2 females; median age, 17.5 years) with scaphoid nonunions and surgery performed within 65 days of the MRI. AVN was diagnosed on the unenhanced MRI when a diffusely decreased T1-W signal was present in the PP and on the enhanced MRI when PP enhancement was less than distal pole enhancement. Surgical absence of PP bleeding was diagnostic of PP AVN. Postoperative osseous union (OU) was assessed with computed tomography and/or radiographs.

RESULTS

Sensitivity, specificity and accuracy for PP AVN were 71, 82 and 78% for unenhanced and 43, 82 and 67% for enhanced MRI. Patients with PP AVN on unenhanced MRI had 86% (6/7) OU; 100% (5/5) OU with vascularized bone grafts and 50% (1/2) OU with nonvascularized grafts. Patients with PP AVN on enhanced MRI had 80% (4/5) OU; 100% (3/3) OU with vascularized bone grafts and 50% (1/2) OU with nonvascularized grafts. Patients with viable PP on unenhanced and enhanced MRI had 91% (10/11) and 92% (12/13) OU, respectively, all but one with nonvascularized graft.

CONCLUSIONS

When PP AVN is evident on MRI, OU is best achieved with vascularized grafts. If PP AVN is absent, OU is successful with nonvascularized grafts.

Operative Treatment of Acute Scaphoid Fractures

Optimal treatment of acute scaphoid fractures is a necessary goal for many reasons. One is that the scaphoid is the most commonly fractured carpal bone. Another is that a missed diagnosis of an acute scaphoid fracture leads to the more challenging situation of a delayed union, non-union and risk for premature radiocarpal arthrosis. Because the scaphoid has an inherent risk for nonunion due to its the tenuous blood supply, timely diagnosis and appropriate treatment are considered critical to achieving acceptable results and to avoiding the consequences of failed union.

Comparison of operative and non-operative treatment of acute undisplaced or minimally-displaced scaphoid fractures: a meta-analysis of randomized controlled trials

Background

Traditionally, acute undisplaced or minimally-displaced scaphoid fractures are treated by casting in short- or long-arm casts. Although reports have shown that operative treatment is safe, effective and produces satisfactory results, outcomes from current studies comparing these two methods are questionable. The aim of this meta-analysis was to evaluate the effects of operative versus non-operative treatment for acute undisplaced or minimally-displaced scaphoid fractures in adults.

Methods

Computerized searches were performed without language restrictions and all randomized controlled studies providing information on the effects of operative versus non-operative treatment on the outcomes of acute undisplaced or minimally-displaced scaphoid fractures were included. The weighted and standard mean difference (WMD and SMD) or the relative risk (RR) were calculated for continuous or dichotomous data respectively.

Results

A total of six studies reported in seven publications were included, representing data on 340 fractures. Meta-analysis indicated that operative treatment resulted in significantly better functional outcomes in the short term when compared with non-operative treatment. Consistently, patients who accepted surgery had a more rapid return to work. Further, surgery was advantageous in preventing delayed union of the fractures, a finding supported by the results of analysis of the time to fracture union. A number-needed-to-treat analysis revealed that more than 20 patients would have to undergo operative treatment to prevent one delayed union.

Conclusion

Acute undisplaced or minimally-displaced scaphoid fractures demonstrate faster recovery with operative treatment; however, the current meta-analysis does not provide evidence supporting the routine use of operative treatment for all acute undisplaced or minimally-displaced scaphoid fractures.

Scaphoid fractures

Scaphoid fractures are the most common carpal bone fracture, usually occurring in young men, although the incidence in women has increased over the past decade. Snuffbox tenderness and/or pain with axial loading of the thumb should be treated as a scaphoid fracture until proved otherwise and the diagnosis confirmed with serial radiographs and/or advanced imaging. Nearly all displaced scaphoid fractures should undergo operative intervention to reduce the risk of nonunion. Nondisplaced fractures have high union rates with cast treatment, but require extended periods of immobilization. Consideration may be given to operative fixation of these fractures to allow early return to sport.

Scaphoid overstuffing: the effects of the dimensions of scaphoid reconstruction on scapholunate alignment

PURPOSE

Osteochondral replacement of the proximal scaphoid has been reported using a vascularized flap from the medial femoral trochlea. A concern with this technique is the loss of stability of the scapholunate relationship with resection of the scaphoid proximal pole. Overexpansion of the scaphoid dimensions (overstuffing) during scaphoid reconstruction with the osteochondral flap may play a role in maintaining scapholunate alignment. Our purpose was to determine if overstuffing the scaphoid can correct rotatory carpal instability in a cadaveric model studied radiographically.

METHODS

The radiolunate angle and scapholunate interval were measured for 5 fresh cadaver wrists. We completely incised the scapholunate interosseous ligament and performed an osteotomy to excise the proximal third of the scaphoid to simulate a proximal pole deficiency nonunion and create a dorsal intercalated segmental instability deformity. Radiographic measurements were repeated. The proximal pole of the scaphoid was replaced with its original piece of bone; radiographic measurements were repeated without scapholunate ligament repair. The osteotomy site was overstuffed with a 4-mm sawbone spacer without scapholunate ligament repair, and radiographs were obtained.

RESULTS

Sectioning of scapholunate ligaments and proximal pole excision successfully created carpal instability demonstrated by abnormal radiolunate angles. Without ligament repair, proximal pole replacement did not restore normal radiolunate angles. Expansion of the scaphoid dimensions corrected radiolunate angles on lateral unloaded radiographs and improved scapholunate intervals on clenched fist radiographs. These findings were statistically significant compared with the unexpanded (replaced) scaphoid.

CONCLUSIONS

These findings suggest that scaphoid reconstruction that results in expansion of the scaphoid's normal dimensions will restore carpal alignment without scapholunate ligament reconstruction.

CLINICAL RELEVANCE

Osteochondral reconstruction of difficult proximal pole nonunions may not require any preservation or reconstruction of scapholunate integrity if the reconstruction expands the normal dimensions of the native scaphoid. Scapholunate interval and carpal alignment may be restored by scaphoid over stuffing. The effects on increased contact pressure and range of motion require further investigation.

Nonoperative treatment for acute scaphoid fractures: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Recommendations for cast immobilization of acute scaphoid fractures vary substantially. We reviewed data from randomized controlled trials comparing nonoperative treatment methods for acute scaphoid fractures to determine the best available evidence.

METHODS

A systematic search of the medical literature from 1966 to 2010 was performed. Two authors independently screened titles and abstracts, reviewed articles, assessed methodological quality according to the Grading of Recommendations Assessment Development and Evaluation system, and extracted data. The primary outcome parameter was nonunion. Data were pooled using random-effects models with standard mean differences for continuous and risk ratios for dichotomous variables, respectively. Heterogeneity across studies was assessed with calculation of the I statistic.

RESULTS

The search resulted in five potentially eligible trials of which four met our inclusion criteria. In total, 523 patients were included in four trials including two evaluating below-elbow casting versus above-elbow casting; one trial comparing below-elbow casting including the thumb versus excluding the thumb; and one trial comparing fractures with a below-elbow cast with the wrist in 20-degrees flexion to 20-degrees extension, with both types excluding the thumb. There were no significant differences in union rate, pain, grip strength, time to union, or osteonecrosis for the various nonoperative treatment methods.

CONCLUSIONS

There is no evidence from randomized controlled trials on physician-based or patient-based outcome to favor any nonoperative treatment method for acute scaphoid fractures.

Headless compression screw fixation of scaphoid fractures

Scaphoid fractures carry significant long-term morbidity and short-term socioeconomic difficulty in the young and active patient population in which they most commonly occur. While cast immobilization results in high rates of radiographic union in nondisplaced scaphoid fractures, internal fixation with headless compression screws has been recommended in cases of displaced fractures. Internal fixation has led to high rates of union in both nondisplaced and displaced fractures with the added benefits of earlier mobilization and return to work and sports. Multiple manufacturers are now offering "second generation" headless compression screws for the internal fixation of scaphoid fractures. The few biomechanical studies that exist demonstrate improved compression forces and load to failure for the newer generation of headless compression screws when compared with the first generation headless compression screw, although it is unclear if these differences are clinically significant.

Optimal fixation of acute scaphoid fractures: finite element analysis

PURPOSE

The hypothesis of this study was that more stable fixation of acute scaphoid fractures may be achieved by a screw placed perpendicular to the fracture plane than along the long axis of the scaphoid, as previously suggested. We examined this assumption on different fracture patterns using a finite element analysis model.

METHODS

A computed tomography scan of an intact scaphoid of a young man provided the data set for all fracture models. We used semiautomatic segmentation to create 3-dimensional computer models of the 3 simple fracture configurations: oblique, transverse waist, and proximal fractures, according to the Herbert classification. Each fracture type was analyzed, using finite elements, for its biomechanical response to 2 types of virtual fixation: a screw placed either perpendicular to the fracture plane or centrally along the long axis of the scaphoid. We measured motion at the fracture plane (in millimeters) and strain in the screw threads (in millipascals).

RESULTS

Considerably less motion was measured at the fracture plane with the perpendicular screw compared with the long axis screw, especially in the oblique-type fractures: (1) Herbert-type B1 oblique fracture mean motion of 0.05 mm (+/-0.03) for the perpendicular screw versus 0.28 mm (+/-0.05) for the long axis screw; (2) B2 transverse waist fracture mean motion of 0.06 mm (+/-0.03) for the perpendicular screw versus 0.18 mm (+/-0.06) for the long axis screw; and (3) B3 proximal fracture mean motion of 0.07 mm (+/-0.01) for the perpendicular screw versus 0.28 mm (+/-0.011) for the long axis screw. Higher strains were measured on the screw placed perpendicular to the fracture.

CONCLUSIONS

According to this model, higher fixation stability is achieved when the scaphoid is fixated perpendicular to the fracture. In transverse waist fractures, a centrally placed screw will also be perpendicular to the fracture, which explains the results of previous models.

The incidence of scaphoid fracture in a military population

BACKGROUND

The rate of occurrence of scaphoid injury is not well known. The incidence of scaphoid fracture has been described mostly in small, injured cohort populations, which may underestimate its frequency. We studied the epidemiology of the scaphoid fracture using a large database in a military population.

PATIENTS AND METHODS

The Defense Medical Epidemiology Database (DMED), a comprehensive database which tracks medical care for all four military services of the United States, was queried for the first occurrence of scaphoid fractures using International Classification of Diseases (ICD)-9 code 814.01. Data were evaluated using multivariate Poisson analysis, controlling for co-variate factors.

RESULTS

We noted 14,704 scaphoid fractures in a population at a risk of 12,117,749 person-years. The unadjusted incidence of scaphoid fracture was 1.21/1000 person-years. Males were significantly more likely to sustain scaphoid fractures, with an adjusted rate ratio (RR) of 1.55 (95% confidence interval (C.I.), 1.47, 1.64), compared to females. The 20-24-year-old age group had the highest incidence of scaphoid fracture at 1.64/1000 person-years, and showed a significantly higher RR compared to the population aged greater than 40 years (adjusted RR 1.55, 95% C.I., 1.38, 1.66). Whites sustained scaphoid fractures at a significantly higher rate than African Americans (adjusted RR 1.32, C.I., 1.26, 1.38).

DISCUSSION/CONCLUSIONS

When compared to the previous data on scaphoid fractures, our study showed a greater incidence of scaphoid fracture at 1.21/1000 person-years in the US military population. These data are derived from a large database which effectively captures the population at risk. Males, the younger age group and the white race were associated with higher rates of scaphoid injury in this specialised military population.

Scaphoid fractures with unusual presentations: a case series

Despite the high incidence of scaphoid fractures, their diagnosis and treatment is often delayed which can lead to complications such as non-union, avascular necrosis, and future arthritis. We present three cases with non-classical mechanisms of injury, leading to a delayed diagnosis in all three cases. Our cases serve to emphasize the importance of a high index of suspicion for the possibility of scaphoid fractures in order to avoid these potential complications.