Comparison of two percutaneous volar approaches for screw fixation of scaphoid waist fractures: radiographic and biomechanical study of an osteotomy-simulated model

A comparative cadaveric study for percutaneous scaphoid fixation: robotic vs freehand

PURPOSES

To compare the robotic-assisted and the traditional freehand percutaneous scaphoid fixation in number of guidewire attempts, duration of fluoroscopy time, amount of radiation dose, and screw centrality.

METHODS

Twenty cadaveric specimens were randomized into either the robotic or freehand group. The scaphoids in both groups were fixed by either the same attending or resident from our hand surgery department. The operation duration, amount of radiation from intraoperative fluoroscopy, total fluoroscopy time, and the number of guidewire attempts were documented and compared. Postoperatively, all the specimens had a computed tomography (CT) scan performed, and the difference in the final position of the screw and the central axis of the scaphoid was examined.

RESULTS

In the robotic group, all the guide wires were satisfactorily positioned within a single attempt, while the median number of attempts in the traditional freehand group was 18 (quaternion 14-65). This also meant that the surgeon in the robotic group experienced significantly lower radiation exposure dose and time as compared to the freehand group. There were no significant differences in the final screw position as compared to the central axis of the scaphoid in both groups. Although there was no difference in surgeon performance in the robotic group, the operative time for the attending was significantly lower as compared to the resident in the freehand group.

CONCLUSION

Robotic-assisted surgery for scaphoid fracture fixation is superior to the traditional freehand method as it facilitates accurate screw placement with lower radiation exposure and fewer guide wire attempts.

Surgical management of slightly or non-displaced corporal scaphoid fractures by retrograde percutaneous screw fixation through the anterior trapezium horn: A single-center retrospective French study of 33 patients between January 2015 and January 2019

INTRODUCTION

Percutaneous screw fixation has recently gained popularity as an alternative to conservative treatment to avoid prolonged immobilization. The placement of a screw in the central axis of the scaphoid has been shown to be biomechanically superior to its eccentricity. Still, it poses difficulties in performing percutaneous screw fixation via both palmar and dorsal approaches.

OBJECTIVE

We describe a palmar percutaneous screwing of corporal fractures of the scaphoid by a simple palmar transtrapezial approach allowing an optimal centering of the screw.

METHOD

We selected patients operated on by the same surgeon using the palmar transtrapezial approach between January 2015 and January 2019 based on the coding used for these fractures and the operative reports. In addition, pre- and postoperative data were collected from the patient's computer and paper records and by telephone contact with the patients.

RESULTS

Thirty-three patients were included. Percutaneous screw fixation of the scaphoid was performed under locoregional anesthesia in the operating room with one arm in the supine position on the arm table. No hyper-extension of the wrist was performed. The Kirchner guidewire passed through the anterior horn of the trapezium and then into the trapezium-scaphoid joint. A screw replaced it after satisfactory centering in the axis of the scaphoid. Management took place on average within 12 days after the trauma. 75.8% were A2 fractures, according to Herbert's classification. The average operating time was 16.63minutes, and in 91% of the cases, the patient was hospitalized for one day. The variation of the scapholunate angle on the preoperative profile radiographs with the angle defined by the axis of the scaphoid screw and the lunate postoperatively was on average 2.94°. One patient presented nonunion, and four showed an undersized screw with a screw overhang requiring revision surgery.

CONCLUSION

The transtrapezial approach to fixation of acute scaphoid fractures facilitates precise percutaneous screw placement in the central axis of the scaphoid. A study of long-term complications, including the degenerative impact on the scaphotrapezial joint, is needed to assess the safety of passage through the anterior horn of the trapezium.

Double-Screw Osteosynthesis in an Unstable Scaphoid Fracture Model: A Biomechanical Comparison of Two Screw Configurations

PURPOSE

Although there is evidence that a single headless compression screw is sufficient for fixation of most scaphoid fractures, double-screw osteosynthesis has been shown to result in higher failure strength and stiffness than a single screw. However, the biomechanical effect of different screw configurations has not been determined.

METHODS

A standardized unstable fracture model was produced in 28 cadaveric scaphoids. Specimens were randomly allocated to 1 of 2 fixation groups using 2 internal compression screws positioned in either the sagittal or coronal plane. A specimen-specific 3-dimensionally-printed customized screw placement and osteotomy device was developed using computer-aided design-generated models derived from computed tomography scan data of each individual scaphoid. Load to failure and stiffness of the repair constructs were evaluated using a mechanical testing system.

RESULTS

There were no significant differences in size, weight, and density between the scaphoid specimens. The average distance between screws was significantly greater in the sagittal group than in the coronal group. There were no significant differences between the coronal and sagittal aligned double screws in load to 2 mm displacement (mean coronal 180.9 ± 109.7 N; mean sagittal 156.0 ± 85.8 N), load to failure (mean coronal 275.9 ± 150.6 N; mean sagittal 248.0 ± 109.5 N), stiffness (mean coronal 111.7 ± 67.3 N/mm; mean sagittal 101.2 ± 45.1 N/mm), and energy absorption (mean coronal 472.6 ± 261.4 mJ; mean sagittal 443.5 ± 272.7 mJ).

CONCLUSIONS

There are no significant biomechanical differences between the sagittal or coronal aligned double headless compression screws in a scaphoid fracture model with bone loss.

CLINICAL RELEVANCE

In cases where double-screw fixation of the scaphoid is being considered, the placement of double screws can be at the discretion of the surgeon, and can be dictated by ease of access, surgical preference, and fracture orientation.

Comparison of conventional and transtrapezial palmar approaches for screw fixation of scaphoid waist fractures: a clinical study

We investigated two palmar approaches for screw fixation of acute scaphoid waist fractures: the conventional percutaneous or transtrapezial approach. Thirty cases who underwent operation from 2013 to 2021 were reviewed (conventional group, 15; transtrapezial approach group, 15). Cross-sections were constructed along the long axis of the scaphoid on postoperative computed tomography to evaluate the screw position, relative to the centre point in the distal-third, midwaist and proximal-third of the bone. The screw could be inserted centrally in the proximal and distal regions using the transtrapezial approach. In the conventional approach, the screw was inserted radially in the distal region, but tended to be positioned centrally in the midwaist and proximal regions. As central placement of the screw in the proximal fragment offers a biomechanical advantage, both approaches can be options for some fracture patterns, while for others, the fracture pattern could influence which approach is better.Level of evidence: IV.

Evaluation of the mechanical properties and clinical application of nickel-titanium shape memory alloy scaphoid arc nail

To investigate the mechanical and biomechanical properties of nickel-titanium (Ni-Ti) shape memory alloy scaphoid arc nail (NT-SAN) fixator as well as study the surgical method of treating carpal scaphoid fractures and evaluate its clinical efficacy. (1) Static and dynamic bending tests with embedded axial bending fixture were conducted to study the mechanical properties. (2) To evaluate biomechanical strength and fatigue, 32 scaphoid samples were classified into four groups to perform the fixation rigidity test: intramedullary Kirschner fixation (group A), Kirschner straddle nail fixation (group B), screw nail fixation (group C), and NT-SAN fixation (group D). Next, 24 scaphoid waist fracture models were classified to conduct fatigue experiments as follows: Kirschner straddle nail fixation (group E), screw nail fixation (group F), and NT-SAN fixation (group G). (3) The Krimmer score chart was used for clinical evaluations. (1) NT-SAN showed excellent mechanical performance and a long lifespan. (2) NT-SAN was fixated with a strong intensity and an anti-fatigue outcome. (3) Ninety-eight interviewed patients were satisfied with the therapeutic effects of the arc nail (satisfaction rate: 95.92%). The designed strength and hardness of NT-SAN corresponded with the anatomical characteristics of the scaphoid, and the designed mechanical properties met the biomechanical requirements of a scaphoid fracture. The fatigue strength can meet the requirements of bone healing after the scaphoid fracture. Clinical trials on NT-SAN scaphoid fracture treatment have shown that the surgery is simple and the clinical results are satisfactory. The therapeutic level of NT-SAN is III; thus, it is worth promoting.

Percutaneous Scaphoid Fixation: Experience Value among Different Approaches

Background  Percutaneous scaphoid osteosynthesis is an attractive and increasingly popular option, as a treatment for acute scaphoid fractures in selected cases, and as an alternative to conservative treatment. The purpose of this study is to assess the radiographic positioning of the screw in percutaneous scaphoid fixation, taking into consideration the surgeons' experience, and the difference between volar and dorsal approaches. Methods  We retrospectively assessed patients undergoing percutaneous scaphoid fixation from 2013 to 2019. Inclusion criteria are as follows: (1) scaphoid waist fractures (Herbert's B2), (2) a minimum of 18 years of age and a maximum of 55 years of age, (3) dominant hand, (4) manual work, (5) minimum follow-up time of 6 months, and (6) without associated lesions. Criteria for correct positioning are as follows: (1) on the axis or parallel to the scaphoid axis with a maximum deviation of 1.5 mm volar/dorsal, (2) without proximal/dorsal prominence, (3) correct scaphoid alignment/reduction, and (4) absence of threads in the fracture site. Radiographs were evaluated separately by a hand surgeon, a general orthopaedic surgeon, and an orthopaedic resident. Results  With a total of 39 patients, a dorsal approach was performed in 10 patients and a palmar approach in 29 patients. We verified a very good interobserver reliability. The hand surgeon's team correctly positioned 15 (83.3%, 15/18), while the other team did 9 correctly (42.9%, 9/21). Comparing teams according to the approach used, the dorsal approach did not show a statistical difference, while the same was not true for the volar approach ( p  < 0.05). Conclusion  This points to a positive impact on the team's experience in the positioning of the screws, and therefore in the benefit of treatment by teams dedicated to the area, while daring to suggest that less-experienced surgeons should utilize the dorsal approach.

Scaphoid Fractures in Athletes

Scaphoid fractures are common injuries in athletes. Most can be treated with cast immobilization, with an expected rate of union of 90% to 95%. Cast treatment, however, has the disadvantages of longer immobilization time, joint stiffness, reduced grip strength, and longer time to return to manual work or athletics. Closed reduction and percutaneous screw fixation generally are preferred in athletes to allow a quicker return to sport; if closed reduction cannot be obtained, open reduction and internal fixation may be required.

Rotational Stability of Scaphoid Waist Nonunion Bone Graft and Fixation Techniques

PURPOSE

Rotational instability of scaphoid fracture nonunions can lead to persistent nonunion. We hypothesized that a hybrid Russe technique would provide improved rotational stability compared with an instrumented corticocancellous wedge graft in a cadaver model of scaphoid nonunion.

METHODS

A volar wedge osteotomy was created at the scaphoid waist in 16 scaphoids from matched-pair specimens. A wedge was inset at the osteotomy site or a 4 × 16-mm strut was inserted in the scaphoid and a screw was placed along the central axis (model 1). The construct was cyclically loaded in torsion until failure. The screw was removed and the proximal and distal poles were debrided. A matching wedge and packed cancellous bone graft or an 8 × 20-mm strut was shaped and fit inside the proximal and distal pole (model 2). A screw was placed and testing was repeated.

RESULTS

In the first model, there was no significant difference in cycles to failure, target torque, or maximal torque between the strut graft and the wedge graft. Cycles to failure positively correlated with estimated bone density for the wedge graft, but not for the strut graft. In the second model, the strut graft had significantly higher cycles to failure, greater target torque, and higher maximal torque compared with the wedge graft. The number of cycles to failure was not correlated with estimated bone density for the wedge or the strut grafts.

CONCLUSIONS

The hybrid Russe technique of inlay corticocancellous strut and screw fixation provides improved rotational stability compared with a wedge graft with screw fixation for a cadaver model of scaphoid waist nonunion with cystic change.

CLINICAL RELEVANCE

The hybrid Russe technique may provide better rotational stability for scaphoid waist nonunions when the proximal or distal scaphoid pole is compromised, such as when there is extensive cystic change, when considerable debridement is necessary, or with revision nonunion surgery.

Which Headless Compression Screw Produces the Highest Interfragmentary Compression Force in Scaphoid Fracture?

BACKGROUND

Interfragmentary compression at the fracture site facilitates healing. Headless compression screws used to treat scaphoid fractures can be grouped as shank screws, conical tapered screws and double component screws. There has been no meta-analysis of biomechanical studies to compare interfragmentary compression produced by the above screws.

METHODS

A computerised search of Pubmed, Embase and OVID database was undertaken to identify the studies. We estimated the weighted mean difference of interfragmentary compression (in Newton) with 95% confidence intervals. Random effects model was selected for meta-analysis.

RESULTS

The pooled estimate of nine studies demonstrated that conical tapered screw produced significantly higher interfragmentary compression force compared to the shank screw (WMD 19.96, 95% CI 11.2-28.8, p < 0.0001, I ² = 99%). The pooled estimate of four studies demonstrated that dual component screw produced significantly higher interfragmentary compression force compared to the shank screw (WMD 16.93, 95% CI 12.3-21.6, p < 0.0001, I ² = 97.7%). The pooled estimate of four studies showed that there was no significant difference in the interfragmentary compression force generated by either conical tapered screw or dual component screw (WMD 3.93, 95% CI - 8.3 to 16.2, p = 0.53, I ² = 99.7%). There was evidence of minimal publication bias.

CONCLUSION

Conical tapered screws and dual component screws produced statistically significant higher interfragmentary compression force at the scaphoid fracture site compared to shank screws. There was no difference in the compression force generated by either conical tapered screw or dual component screw.

Deviations in positioning variable pitch screws- scaphoid waist fractures

INTRODUCTION

Operative therapy using a headless cannulated variable pitch compression screw is the gold standard for the treatment of instable scaphoid fractures.

HYPOTHESIS

Deviation from the central placement is associated with a loss of stability and stiffness.

MATERIAL AND METHODS

An artificial bone model was manufactured and different screw positions (central, 10° and 20° to the long axis) were assessed. A shearing test with axial force on the 45° flexed scaphoid was applied.

RESULTS

The inserted variable pitch screw showed the highest stiffness and failure force in a position in the long axis. At 10 degrees, a slight decrease in stiffness (32.7N/mm±9.3N/mm) and failure force (41.6N±13.2N) was observed, while a significant reduction in stiffness (29.3N/mm±4.6N/mm) and failure force (50.3N±19.5N) was measured at 20 degrees.

DISCUSSION

Deviations in the angle of insertion of the compression screw cause loss in failure force, thus deviations from the central placement is associated with less stability and stiffness.

LEVEL OF PROOF

Controlled laboratory study (basic science study, biomechanical testing).

Acute Scaphoid Waist Fracture in the Athlete

Scaphoid fractures are the most common carpal fracture and the most challenging. Although appropriately managing acute scaphoid waist fractures is a priority, it also is of primary importance to make a diagnosis acutely. Scaphoid waist fractures can occur with low-energy trauma and lead to mild symptoms. A tendency to minimize symptoms and low level of initial disability lead to delay in diagnosis. Displaced scaphoid fractures require operative intervention uniformly. Although nondisplaced fractures can heal with nonoperative treatment, management of these injuries is affected by patient demands. In high-level athletes, operative treatment of nondisplaced injuries may lead to earlier return to sport.

Approach to the Perpendicular Fixation of a Scaphoid Waist Fracture-A Computer Analyzed Cadaver Model

PURPOSE

In scaphoid fracture screw fixation, the screw is commonly placed along the long axis of the bone, without consideration of the fracture plane. This position is not perpendicular to transverse waist fractures or to the more common horizontal oblique fractures. Our aim was to examine the feasibility and describe possible approaches to, placing a screw perpendicular and in the center of the scaphoid waist fracture.

METHODS

Computed tomography of 12 cadaver wrists was performed in 3 positions to examine possible approaches in flexion, neutral, and extension of the wrist. The scans were evaluated using a 3-dimensional model that simulated horizontal oblique (60°) and transverse (90°) fractures. We examined all possible approaches for screw positioning and their deviation from the axis perpendicular to the fracture and in the center of its plane.

RESULTS

The preferred approaches for a perpendicular screw in a horizontal oblique fracture were found to be proximal-dorsal in flexion or transtrapezial in the extended or neutral positions (through the volar-radial trapezium). In transverse fractures, the possible approaches were proximal-dorsal or transtrapezial in the flexed or neutral positions and distal in the extended position (volar to volar-radial trapezium). In these approaches, the screw could be placed perpendicularly (deviating by < 10°) and in the center of the fracture in all specimens.

CONCLUSIONS

According to this model, it appears feasible to place a perpendicular screw in the center of a horizontal oblique waist fracture using a proximal-dorsal approach in flexion or a transtrapezial approach in neutral or extension positions of the wrist. Palpable landmarks may be used as additional guides to direct these approaches according to the clinical setting.

CLINICAL RELEVANCE

Perpendicular screw fixation of horizontal oblique or transverse scaphoid waist fractures is a possible option, if chosen for its biomechanical advantages.

Antegrade Versus Retrograde Technique for Fixation of Scaphoid Waist Fractures: A Comparison of Screw Placement

Background  Scaphoid waist fractures are often treated using headless compression screws using dorsal or volar approaches. Objectives  The purpose of this study is to compare differences in screw position using a volar (retrograde) or dorsal (antegrade) approach. Patients and Methods  A total of 82 patients were retrospectively evaluated: 41 treated with a volar and 41 with a dorsal approach were selected. Postoperative radiographs were reviewed by three observers who rated screw location in the proximal pole, waist, and distal pole. Results  Thirty-four patients (83%) in the antegrade group had central screw placement in the waist of the scaphoid in posteroanterior and lateral planes compared with 14 (34.9%) in the retrograde group ( p  < 0.05). For the antegrade group, the screw was central in 217 of 246 zones (88.2%) compared with 127 of 246 (51.6%) in the retrograde group ( p  < 0.05). Conclusions  The dorsal antegrade approach appears to allow the surgeon to achieve central screw placement along all three scaphoid regions. Level of Evidence  This is Level III study.

The Vascular Anatomy of the Scaphoid: New Discoveries Using Micro-Computed Tomography Imaging

PURPOSE

The purpose of this study was to investigate the intraosseous vascular anatomy of the scaphoid using recent advances in micro-computed tomography (micro-CT) imaging and 3-dimensional reconstruction. We also studied the effect of scaphoid shape and screw position on the intraosseous vascular structure.

METHODS

Thirteen upper extremities were injected with a contrast agent. The scaphoid bones were extracted and scanned using a micro-CT scanner. The vascular impact of screw insertion at various axes through the scaphoid was calculated and compared using the generated 3-dimensional models. The specimens were 3-dimensionally-printed and the morphology was assessed according to bone dimensions. A relationship between the internal vascular patterns and these morphological features was determined.

RESULTS

All specimens received vascular inflow from the dorsal ridge forming a vascular network that supplied an average of 83% of the bone's volume. This network was supplemented in 4 specimens with volar vessels entering at the waist. Another network was identified, created by vessels entering volarly at the tubercle, which supplied the remainder of the scaphoid. One specimen did not receive any vessels at the tubercle. With regards to screw placement, screws placed in the central axis were the least disruptive to the internal vascularity, followed by the antegrade (dorsal) insertion axis. Two morphological bone types were identified: type I or full scaphoids and type II or slender scaphoids. Type I possessed a more robust internal vascular network than type II scaphoids.

CONCLUSIONS

This study identifies 2 distinct types of scaphoid morphology with 1 of them having a less robust blood supply, which may prove to be related to development of nonunion, avascular necrosis, or Preiser disease. Central axis and antegrade (dorsal) screw fixation may be least disruptive to the internal blood supply.

CLINICAL RELEVANCE

Safer fixation of the scaphoid bone may be achieved by knowledge of intraosseous vascular patterns.

The Author's Technique for the Management of Unstable Scaphoid Nonunions: Tips and Tricks

This article presents historical aspects, rationale, indications, planning, and execution of anterior interpositional bone grafting technique for unstable scaphoid nonunions. The author's original technique considers four points: (1) preoperative planning based on comparative anteroposterior radiographs in maximal ulnar deviation was used to calculate resection zone, size of the graft, and scaphoid length; (2) a volar approach was used; (3) an iliac crest wedge-shaped corticocancellous graft was interposed; and (4) Kirschner wires were inserted for fixation. Contemporary refinements of the technique including a modification to treat nonunions with failed previous screw fixation with tricks and hints and results are shown.

Biomechanical Strength of Scaphoid Partial Unions

Background  It remains unknown how much force a partially united scaphoid can sustain without refracturing. This is critical in determining when to discontinue immobilization in active individuals. Purpose  The purpose of this study was to test the biomechanical strength of simulated partially united scaphoids. We hypothesized that no difference would exist in load-to-failure or failure mechanism in scaphoids with 50% or more bone at the waist versus intact scaphoids. Materials and Methods  Forty-one cadaver scaphoids were divided into four groups, three experimental osteotomy groups (25, 50, and 75% of the scaphoid waist) and one control group. Each was subjected to a physiologic cantilever force of 80 to 120 N for 4,000 cycles, followed by load to failure. Permanent deformation during physiologic testing and stiffness, max force, work-to-failure, and failure mechanism during load to failure were recorded. Results  All scaphoids survived subfailure conditioning with no significant difference in permanent deformation. Intact scaphoids endured an average maximum load to failure of 334 versus 321, 297, and 342 N for 25, 50, and 75% groups, respectively, with no significant variance. There were no significant differences in stiffness or work to failure between intact, 25, 50, and 75% groups. One specimen from each osteotomy group failed by fracturing through the osteotomy; all others failed near the distal pole loading site. Conclusion  All groups behaved similarly under physiologic and load-to-failure testing, suggesting that inherent stability is maintained with at least 25% of the scaphoid waist intact. Clinical Relevance  The data provide valuable information regarding partial scaphoid union and supports mobilization once 25% union is achieved.

Scaphoid Fracture Fixation in a Nonunion Model: A Biomechanical Study Comparing 3 Types of Fixation

PURPOSE

Union of a scaphoid fracture after fixation is influenced by various factors, one of which is fracture stability. This study aims to compare the biomechanical stability of 3 different types of scaphoid fracture fixation in a scaphoid nonunion model.

METHODS

Thirty cadaveric scaphoid specimens were assigned to one of 3 different fixation groups: (1) single 3.0-mm compression screw, (2) two 2.2-mm screws, and (3) scaphoid plate. A 3-mm volar wedge osteotomy was created at the scaphoid waist to simulate a nonunion model. The primary outcome measure was load to failure, whereas secondary outcome measures were load to 2-mm displacement, energy absorbed, stiffness, and mode of failure, recorded by video and retrieval analysis.

RESULTS

There was a significantly lower load to failure in the single screw construct compared with that in the double screw (mean difference 187.2 N) and plate fixation constructs (mean difference 150.7 N). The mean load to 2-mm displacement in the single screw construct (91.5 N) was also significantly lower than that in the double screw (181.8 N) and plate fixation constructs (197.2 N). There was a significantly lower stiffness with the single screw fixation compared with that of the double screws (mean difference 85.4 N/mm), and lower energy absorbed with single screws when compared with that of double screws (mean difference 386.5 mJ) and when compared with plate fixation (mean difference 270.8 mJ).

CONCLUSIONS

In this biomechanical study comparing fixation methods using a model of scaphoid nonunion with bone loss, we found that double screws or plate fixation demonstrated significantly greater stability, stiffness, and energy absorption when compared with a single compression screw. We found no discernible differences between double screw fixation and the plate groups.

CLINICAL RELEVANCE

The use of double screws or plate fixation in a nonunion setting may allow accelerated rehabilitation without compromise to fracture stability.

Scaphoid screw fixation perpendicular to the fracture plane: Comparing volar and dorsal approaches

INTRODUCTION

To percutaneously fixate a midwaist scaphoid fracture, both volar and dorsal approaches are considered valid options although they may have different screw insertion angles relative to the scaphoid fracture plane influencing fixation stability. In this virtual simulation study, we investigated the accessibility of placing a screw perpendicularly to the fracture plane in transverse and horizontal oblique scaphoid midwaist fracture models and compared standard volar and dorsal approaches.

MATERIAL AND METHODS

Computed tomography scans of 38 healthy wrists were used to obtain virtual 3-dimensional wrist models in flexion and extension. In case the trapezium in volar approach or the distal radius in dorsal approach obstructed the screw axis perpendicular to the fracture plane, an alternative non-obstructed screw axis was chosen as close as possible to the perpendicular axis. The deviation angle between the best possible non-obstructed screw placement and true perpendicular screw placement was quantified.

RESULTS

For transverse fractures, the average deviation angle (±standard deviation) was 8° (±5°) in volar approach, and 0° (±0°) in dorsal approach. For horizontal oblique fractures, these angles were 40° (±6°) and 14° (±8°), respectively.

DISCUSSION

In our simulations, compared to the volar approach, the dorsal approach provided the most precise screw placement perpendicular to the fracture plane, with the largest differences for horizontal oblique fractures. When taken in addition to screw purchase, thread engagement and protrusion risk, information about screw orientation may help surgeons in deciding between percutaneous approaches in scaphoid surgery on which there is currently no consensus.

LEVEL OF EVIDENCE

N/A.

Percutaneous, Transtrapezial Fixation without Bone Graft Leads to Consolidation in Selected Cases of Delayed Union of the Scaphoid Waist

Purpose  We evaluated clinical and radiographic outcome of percutaneous transtrapezial fixation of the scaphoid delayed union or nonunion using a headless bone screw without bone grafting. Methods  Sixteen patients with delayed union or nonunion of the scaphoid were included in this retrospective study between 2006 and 2011. All patients had a delayed presentation of scaphoid fracture, and none of them was treated conservatively elsewhere. Patients with bone graft, sclerotic bone debridement, or displacement of the fragment at the nonunion site were excluded. A percutaneous transtrapezial fixation technique was used in all cases. Patients were reviewed until clinical and radiographic union was observed. At the final follow-up, DASH (Disabilities of the Arm, Shoulder and Hand) and PRWHE (Patient-Rated Wrist and Hand Evaluation) outcome scores were completed. Results  Radiographic union was obtained in 15 out of 16 patients (94%) at an average follow-up of 36 months (range: 12-98 months). No complications from the percutaneous technique were noted. The average DASH score was 6 (range: 0-39) and the average PRWHE score was 10 (range: 0-56). No statistical significant difference in range of motion and grip strength was found between the operated side and the contralateral side. Conclusion  Percutaneous transtrapezial screw fixation for delayed or nonunion of selected scaphoid fractures without bone grafting is promising. At a mean of 4 months, 94% union was obtained with good functional results when there was no sclerosis, minimal osteolysis, and no displacement at the scaphoid nonunion site. Type of Study  Therapeutic study. Level of Evidence  IV.

Percutaneous Screw Fixation for Scaphoid Fractures

Treatment of nondisplaced scaphoid waist fractures has evolved from conventional cast immobilization to percutaneous screw insertion. This study assessed clinical and radiologic outcomes of volar percutaneous screw fixation for 15 type B2 scaphoid fractures (according to the Herbert and Fisher classification). All patients were followed for an average of 33 months (range, 6-50 months). All fractures achieved radiographic union at an average of 57 days (range, 35-70 days), requiring no additional procedures. None of the patients showed radiographic signs of osteoarthritis, osteonecrosis of the scaphoid, or hardware-related complications. For scaphoid waist fractures without collapse, percutaneous screw fixation provided satisfactory results with a high rate of union, early return of function, and minimal complications. [Orthopedics. 2017; 40(4):e729-e734.].

Three-dimensional comparison of alternative screw positions versus actual fixation of scaphoid fractures

PURPOSE

The recommended technique for the fixation of a scaphoid waist fracture involves a headless compression screw placed in the proximal fragment center. This is usually accomplished by placing a longitudinal axis screw as visualized by fluoroscopy. The screw length has been shown to have a biomechanical advantage. An alternative to these options, which has been debated in the literature, is a screw placed perpendicular to the fracture plane and in its center. The perpendicular screw may have a biomechanical advantage despite the fact that it may be shorter. This study examined the differences in location and length in actual patients between a screw in the center of the proximal fragment with a longitudinal axis screw, and the actual fixating screw. These were then compared to a perpendicular axis screw.

METHODS

Pre- and post-operative CT scans of 10 patients with scaphoid waist fractures were evaluated using a 3D computer model. Comparisons were made between the length, location and angle of actual and virtual screw alternatives; namely, a screw along the central third of the proximal fragment (central screw axis) where the scaphoid longitudinal axis was calculated mathematically (longitudinal screw axis) and a screw placed at 90° to the fracture plane and in its center (perpendicular screw axis).

RESULTS

The longitudinal axis screw was found to be significantly longer than the other axes (28.3mm). There was a significant difference between the perpendicular axis screw and the location and angle of the other screw axis, but it was only shorter than the longitudinal screw (23.6mm versus 25.5mm for the actual screw; ns.).

CONCLUSIONS

A computed longitudinal axis screw is longer than a central or actual screw placed longitudinally by visual inspection by the surgeon. Although it needs to be placed using computer assisted (CAS) techniques, it may have the biomechanical advantages of a longer screw in a similar trajectory. The perpendicular screw was found to be significantly different in position and angle but not shorter than the actually placed screw. It has biomechanical advantages and does not require visualization with CAS methods, making it the more attractive alternative.

Acute Scaphoid Fractures: A Critical Analysis Review

Nondisplaced scaphoid fractures can be effectively treated nonoperatively, with union rates approaching or, in some series, exceeding the rates attained with operative intervention. The evidence supports equal outcomes when using a short arm or long arm cast for the closed treatment of nondisplaced scaphoid fractures. Also, equivalent outcomes have been demonstrated with or without a thumb spica component to the cast. Operative intervention is the recommended treatment for displaced scaphoid fractures. Advanced imaging should be obtained if clinical suspicion is present for a scaphoid fracture with negative radiographs more than 2 weeks after the injury. In some settings, it may even be more cost-effective to obtain advanced imaging sooner.

Comparison of Dorsal and Volar Percutaneous Approaches in Acute Scaphoid Fractures: A Meta-Analysis

The dorsal approach allows better central screw placement along the long axis of the scaphoid compared with the volar approach in managing acute scaphoid fractures. However, it is unclear whether the dorsal approach leads to better clinical outcomes than the volar approach. This meta-analysis compared clinical outcomes, including the incidence of nonunion, postoperative complications, overall functional outcome, postoperative pain, grip strength, and range of wrist motion, between the dorsal and volar percutaneous approaches for the management of acute scaphoid fractures. Seven studies met the criteria for inclusion in the meta-analysis. The proportion of patients who developed nonunion (OR 0.74, 95% CI: 0.21 to 2.54; P = 0.63) and postoperative complications (OR 1.05, 95% CI: 0.45 to 2.44; P = 0.91) did not differ significantly between the dorsal and volar approaches. Both approaches also led to similar results in terms of overall functional outcome (95% CI: -0.39 to 0.22; P = 0.57), postoperative pain (95% CI: -0.52 to 0.46; P = 0.92), grip strength (95% CI: -4.56 to 1.02; P = 0.21), flexion (95% CI: -2.86 to 1.13; P = 0.40), extension (95% CI: -1.17 to 2.67; P = 0.44), and radial deviation (95% CI: -1.94 to 2.58; P = 0.78). However, ulnar deviation (95% CI: -7.48 to 0.05; P = 0.05) was significantly greater with the volar approach. Thus, orthopedic surgeons need to master both the dorsal and volar percutaneous approaches because not all acute scaphoid fractures can be dealt with completely with one approach.

Mechanical Evaluation of Four Internal Fixation Constructs for Scaphoid Fractures

BACKGROUND

The objective of this study was to compare the mechanical performance of 4 different constructs for fixation of oblique scaphoid fractures.

METHODS

Twenty-eight synthetic scaphoids underwent an oblique osteotomy along the dorsal sulcus. Each was randomly assigned to fixation by 1 of 4 methods: two 1.5-mm headless compression screws, one 2.2-mm screw, one 3-mm screw, or a 1.5-mm volar variable-angle plate. After fixation, scaphoids were potted at a 45° angle and loaded at the distal pole by a hydraulically driven mechanical testing system plunger until the fixation failed. Excursion and load were measured with a differential transformer and load cell, respectively. From these data, the stiffness, load-to-failure, and maximum displacement of each construct were calculated.

RESULTS

The 2.2-mm screw demonstrated the highest stiffness and the two 1.5-mm screws had the lowest. However, there were no significant differences among the fixation methods in terms of stiffness. Both 2.2- and 3-mm screw constructs had significantly higher loads-to-failure than two 1.5-mm screws. The maximum load for the plate approached, but did not achieve, statistical significance compared with the 1.5-mm screws. There was no significant difference among constructs in displacement.

CONCLUSIONS

All constructs demonstrated similar mechanical properties that may provide sufficient stability for effective clinical use. Given their significantly higher loads-to-failure, a 2.2- or 3-mm screw may be superior to two 1.5-mm screws for fixation of unstable scaphoid fractures. The volar plate did not have superior mechanical characteristics to the compression screws.

Radiographic Parameters to Predict Union After Volar Percutaneous Fixation of Herbert Type B1 and B2 Scaphoid Fractures

PURPOSE

To study the angle of screw placement in relation to the scaphoid fracture plane and its effect on union after percutaneous fixation of scaphoid waist fractures.

METHODS

Twenty-four consecutive scaphoid waist fractures were retrospectively evaluated for the orientation of screws in relation to the fracture plane using a method in which the sum-of-smaller angles (SSA) in 3 different radiographs were used to correlate with time to fracture union.

RESULTS

All but one patient achieved union after percutaneous fixation of the scaphoid. Another patient required revision surgery within the study period for inadequate fixation. A shortened time to union was significantly correlated to larger SSA.

CONCLUSIONS

SSA may be a reasonable predictor of union after percutaneous fixation of scaphoid waist fracture. It can be reliably calculated using plain radiographs. An SSA of 190° or more correlated with union by 8 weeks postoperatively.

Transtrapezial Approach for Fixation of Acute Scaphoid Fractures

Introduction

The transtrapezial approach for fixation of acute scaphoid fractures facilitates precise percutaneous placement of a screw along the central axis of the scaphoid, which has been shown to be biomechanically superior.

Step 1 Position the Patient Surgeon and Fluoroscopy Equipment

Correctly position the patient, surgeon, and fluoroscopy equipment before starting the procedure.

Step 2 Mark the Skin

Mark the central axis of the scaphoid on the skin along the anteroposterior and lateral (optional) planes as the markings allow visual control for insertion of the guidewire.

Step 3 Stab Incision

Make a volar stab incision over the distal half of the trapezium.

Step 4 Insert the Guidewire

Insert the guidewire through the trapezium along the central axis of the scaphoid, which is the critical step of the procedure.

Step 5 Drilling

Drill the trapezium and the distal cortex of the scaphoid to allow easy insertion of the screw.

Step 6 Length Measurement

Precisely measure the scaphoid length to determine the appropriate screw length.

Step 7 Insert the Screw

Insert the selected screw over the guidewire.

Results

In our report on the first results of this technique in forty-one patients with an acute nondisplaced scaphoid waist fracture, all fractures united within ten weeks (mean, 6.4 weeks) and the modified Mayo wrist score was good (four patients) or excellent (thirty-seven patients) at a mean follow-up of thirty-six months (range, fourteen to sixty-eight months).IndicationsContraindicationsPitfalls & Challenges.

The Accuracy of Pain Measurement in Diagnosis of Scaphoid Bone Fractures in Patients with Magnetic Resonance Imaging: Report of 175 Cases

Introduction:

Scaphoid fracture is the most common fracture among the bones of the wrist. Plain radiography has a sensitivity of 59 to 79 percent for the diagnosis of scaphoid fracture after injury. Casting is done to avoid complications in patients with suspected fractures with normal radiography. Magnetic resonance imaging (MRI) has a sensitivity of 100% and a specificity of 99%. To avoid unnecessary casting and high costs, we decided to offer a way more efficient than radiography and less costly than MRI.

Material and Methods:

In the present study, 175 patients with suspected scaphoid fracture along with snuff box tenderness and normal radiography were enrolled in the study. On arrival, patients’ pain score were determined using visual analog scale method with anatomical snuffbox tenderness and then MRI was performed on the patients’ wrist and the results were recorded for patient in the check list. The data was then aggregated and analyzed.

Results:

The result of MRI for fracture was negative for 90.9% and positive for 9.1%. The mean pain score was 7.3 in negative MRI group and 8.75 in positive MRI group, considering a significant difference. ROC curve graph showed that the sensitivity and specificity will be 87% and 57%, respectively for scores 7.5 and higher and 75% and 72%, respectively for scores 8.5 and higher.

Conclusion:

It seems that although this method, beside other criteria in the diagnosis of fractures, can be useful in future studies, it would not be helpful in fracture detection.

Arthroscopic Management of Scaphoid Nonunions

The difficulty in healing scaphoid nonunions is challenged further by the dynamic, unstable nature of the fracture-fragment interface. Recently, several investigators have introduced a minimally invasive technique for scaphoid nonunion repair, which has the advantages of minimal morbidity and accurate articular reduction, resulting in less postoperative stiffness and increased functional outcomes. However, failure to recognize the critical steps during minimally invasive surgery can result in incorrect treatment or limit any chances for successful bone repair. We reviewed the selected literature pertinent to arthroscopic techniques in the treatment of scaphoid nonunions. Furthermore, we presented a new arthroscopic approach that can be used in place of traditional formal open exposures in challenging cases of nonunion.

Transtrapezial Approach for Fixation of Acute Scaphoid Fractures: Rationale, Surgical Techniques, and Results: AAOS Exhibit Selection

The ideal position for a screw used for scaphoid fixation is central. The purpose of this study was to compare the current volar percutaneous approaches used for scaphoid fracture fixation, explore different options to improve central screw placement, and describe our experience with the transtrapezial approach.

Management of complications of wrist fractures

This article reviews the most common complications associated with the management of carpal fractures. Discussion focuses on the recognition of commonly "missed" fractures and fracture patterns and the negative sequelae that can result from these delayed diagnoses. The pitfalls of conservative treatment of specific carpal fractures are reviewed, and the most common complications resulting from the operative management of carpal injuries are described.