The morphology of proximal pole scaphoid fractures: implications for optimal screw placement

Rethinking Scaphoid Fixation

Scaphoid fixation, whether for acute injuries or nonunion, is made challenging by the small and intra-articular nature of the most commonly fractured carpal bone. The purpose of this article is to review the techniques to simplify scaphoid fixation and to optimize healing and early return to activity.

Scaphoid Malunion: Incidence, Predictors, and Outcomes

Background  Scaphoid malunion is rarely reported. Previous literature has attributed loss of carpal height and degenerative changes to scaphoid malunion, but the percentage of asymptomatic malunions remains unknown. Purpose  The authors of this study aim to define predictors of malunion and outcomes associated with scaphoid malunion. Methods  Institutional board review was obtained prior to evaluating medical records of patients 18 years and older who were treated for scaphoid fractures and/or nonunion between 2000 and 2020. The following data were collected for each patient: age, gender, fracture location, surgical technique, time to union, and whether malunion resulted. Malunion was defined using a lateral intrascaphoid angle (LISA) >45 degrees and height-to-length ratio (HLR) >60. Pain scores, range of motion (ROM), and secondary surgery were also evaluated. Results  Overall, 355 scaphoid injuries, including 196 acute fractures and 159 nonunions, were evaluated in this analysis. Of these, 55 scaphoids (15%) met the definition of malunion. Of these patients, 23% were female. The mean age at the time of injury was 29 years. Nonunion cases were more likely than acute cases to be associated with malunion. Proximal pole fractures were more likely to associated with malunion than waist fractures. When controlling for nonunion and fracture location, malunited scaphoids were not associated with any significant difference in pain score, ROM, or secondary surgery, compared with nonmalunion cases. A total of 10 patients (3.3%) without malunion and 2 patients (3.6%) with malunion went on to a secondary surgery. Final extension/flexion was 67/67 degrees and 56/59 degrees in nonmalunion and malunion groups, respectively, but these differences were not significant. Conclusion  Compared with scaphoid injuries that do not result in malunion, scaphoid injuries that heal into malunion have similar outcomes. While scaphoid malunion in a single case or series may be associated with poor outcomes, this study suggests that scaphoid malunions do not have worse functional outcomes. Level of Evidence  This is a Level IV study.

A Comparison Between Robotic-Assisted Scaphoid Screw Fixation and a Freehand Technique for Acute Scaphoid Fracture: A Randomized, Controlled Trial

PURPOSE

We compared robotic-assisted scaphoid screw fixation to conventional technique in terms of accuracy, surgical times, radiation exposure, and clinical outcomes, including range of motion, grip strength, functional score, and complications.

METHODS

This study was a registered, prospective, randomized, controlled trial. From May 2019 to December 2019, 1 surgeon performed 18 robotic-assisted and 18 conventional scaphoid screw fixations and these patients were eligible for participation in this study. Surgical time, including the time of the overall procedure, set-up time, and time for ideal guidewire placement, was recorded. The number of guidewire attempts also was recorded. All patients were evaluated clinically and radiographically at follow-up with respect to the severity of pain, wrist motion, grip strength, complications, and Mayo modified wrist score.

RESULTS

The average set-up time and overall time of the procedure were longer in the robotic-assisted than in the conventional groups, while the mean guidewire insertion time and the mean guidewire attempts was less in the robotic-assisted group than that of the conventional group. The overall radiation exposure was lower in the robotic group.

CONCLUSIONS

Robotic-assisted technique provided a useful tool to improve implantation accuracy and shorten radiation exposure. Additional cost and prolonged duration of surgery without evidence of improved clinical scores may limit widespread acceptance of this technique.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Arthroscopic bone graft and fixation for proximal scaphoid nonunions

AIMS

This study aims to report the outcomes in the treatment of unstable proximal third scaphoid nonunions with arthroscopic curettage, non-vascularized bone grafting, and percutaneous fixation.

METHODS

This was a retrospective analysis of 20 patients. All cases were delayed presentations (n = 15) or failed nonoperatively managed scaphoid fractures (n = 5). Surgery was performed at a mean duration of 27 months (7 to 120) following injury with arthroscopic debridement and arthroscopic iliac crest autograft. Fracture fixation was performed percutaneously with Kirschner (K)-wires in 12 wrists, a headless screw in six, and a combination of a headless screw and single K-wire in two. Clinical outcomes were assessed using grip strength, patient-reported outcome measures, and wrist range of motion (ROM) measurements.

RESULTS

Intraoperatively, established avascular necrosis of the proximal fragment was identified in ten scaphoids. All fractures united within 16 weeks, confirmed by CT. At a mean follow-up of 31 months (12 to 64), there were significant improvements in the Patient-Rated Wrist Evaluation, Mayo Wrist Score, abbreviated Disabilities of the Arm, Shoulder and Hand score, wrist ROM, grip strength, and the patients' subjective pain score. No peri- or postoperative complications were encountered.

CONCLUSION

Our data indicate that arthroscopic bone grafting and fixation with cancellous autograft is a viable method in the treatment of proximal third scaphoid nonunions, regardless of the vascularity of the proximal fragment. Cite this article: Bone Joint J 2022;104-B(8):946-952.

CSR-Net: Cross-Scale Residual Network for multi-objective scaphoid fracture segmentation

The scaphoid is located in the carpals. Owing to the body structure and location of the scaphoid, scaphoid fractures are common and it is difficult to heal. Three-dimensional reconstruction of scaphoid fracture can accurately display the fracture surface and provide important support for the surgical plan involving screw placement. To achieve this goal, in this study, the cross-scale residual network (CSR-Net) is proposed for scaphoid fracture segmentation. In the CSR-Net, the features of different layers are used to achieve fusion through cross-scale residual connection, which realizes scale and channel conversions between the features of different layers. It can establish close connections between different scale features. The structures of the output layer and channel are designed to establish the CSR-Net as a multi-objective architecture, which can realize scaphoid fracture and hand bone segmentations synchronously. In this study, 65 computed tomography images of scaphoid fracture are tested. Quantitative metrics are used for assessment, and the results obtained show that the CSR-Net achieves higher performance in hand bone and scaphoid fracture segmentations. In the visually detailed display, the fracture surface is clearer and more intuitive than those obtained from other methods. Therefore, the CSR-Net can achieve accurate and rapid scaphoid fracture segmentation. Its multi-objective design provides not only an accurate digital model, but also a prerequisite for navigation in the hand bone.

Reconstruction of proximal pole scaphoid non-union with avascular necrosis using proximal hamate: A four-case series

Union of proximal pole scaphoid fracture is challenging because the vascular supply is limited. The avascular necrosis accompanying non-union and progressive fragmentation make surgical reconstruction difficult. The present study aimed to report short-term results of reconstruction with proximal hamate in proximal pole scaphoid non-union with avascular necrosis. Four patients (3 male, 1 female) were assessed for non-union following proximal pole scaphoid fracture. Mean age was 25.7 years (range, 22-35 years). Mean interval between injury and reconstruction was 7.5 years (range, 5-9 years). In 3 patients, no treatment was given following the fracture and in the other internal fixation was performed following cast immobilization. The non-united avascular proximal scaphoid was resected and reconstructed with proximal hamate autograft. Mean follow-up was 14.0 months (range, 9-22 months) after reconstruction. At the last control, cases were evaluated in terms of clinical and functional status, and radiologic union was determined on CT scan. Three patients reported subjective decrease in pain. Mean grip strength proportionally to the unaffected side was 24% (range, 8-51%), mean flexion-extension was 55.3% (range, 21-60%), and radial-ulnar deviation was 63.6% (range, 25-100%). Mean QuickDASH score was 32.3 (range, 13.6-52.2). Union was observed in all patients. Proximal hamate reconstruction provided union and pain relief, but only moderate objective functional results. It can be used as an alternative technique in proximal pole scaphoid non-union with avascular necrosis.

Robot-assisted double screw fixation of minimally displaced scaphoid waist fracture nonunions or delayed unions without bone graft

We retrospectively reviewed 12 minimally displaced fractures of the scaphoid waist in 12 patients who developed delayed or nonunions with or without conservative treatment. Mean time between injury and surgery was 6 months (range 3-12). The fractures were stabilized with double screws, which were percutaneously inserted with robot assistance, and without bone grafting. All fractures united at a mean of 8 weeks (range 6-10) after surgery. The patients were followed-up at 6 months and 1 year. The patients recovered good wrist function. No major postoperative complications were reported, and the patients returned to their usual level of activity. Robot assistance gave a high degree of accuracy when placing the cannulated screws since only two attempts were needed for correct placement of the guide wires. We explain the high union incidence by patient selection, good stabilization and not disturbing the vascular supply.Level of evidence: IV.

Factors Associated with Scaphoid Nonunion following Early Open Reduction and Internal Fixation

Background  Nonunion after open reduction and internal fixation (ORIF) of scaphoid fractures is reported in 5 to 30% of cases; however, predictors of nonunion are not clearly defined. Objective  The purpose of this study is to determine fracture characteristics and surgical factors which may influence progression to nonunion after scaphoid fracture ORIF. Patients and Methods  We performed a retrospective case-control study of scaphoid fractures treated by early ORIF between 2003 and 2017. Inclusion criteria were surgical fixation within 6 months from date of injury and postoperative CT with minimum clinical follow-up of 6 months to evaluate healing. Forty-eight patients were included in this study. Nonunion cases were matched by age, sex, and fracture location to patients who progressed to fracture union in the 1:2 ratio. Results  This series of 48 patients matched 16 nonunion cases with 32 cases that progressed to union. Fracture location was proximal pole in 15% (7/48) and waist in 85% (41/48). Multivariate regression demonstrated that shorter length of time from injury to initial ORIF and smaller percent of proximal fracture fragment volume were significantly associated with scaphoid nonunion after ORIF (63 vs. 27 days and 34 vs. 40%, respectively). Receiver operating curve analysis revealed that fracture volume below 38% and time from injury to surgery greater than 31 days were associated with nonunion. Conclusion  Increased likelihood for nonunion was found when the fracture was treated greater than 31 days from injury and when fracture volume was less than 38% of the entire scaphoid. Level of Evidence  This is a Level III, therapeutic study.

Robot-assisted percutaneous scaphoid fracture fixation: a report of ten patients

This study reports the technique, efficacy and safety of robotic-assisted, computer-navigated, percutaneous fixation of scaphoid fractures. Ten males with acute undisplaced waist fractures underwent fixation with this method using a commercially available three-dimensional fluoroscopy unit and robotic navigation system. The mean total operative duration was 40 minutes, which comprised of a set-up time of 18 minutes and planning and surgical time of 22 minutes. All patients required only a single guidewire insertion attempt, and there were no screw protuberances or other complications. All fractures united at a mean of 8 weeks. At a mean follow-up of 6.5 months (range 6-8), the mean Mayo wrist score was 96, patient-rated wrist evaluation was 2, flexion-extension arc was 96% and grip strength was 91% of the contralateral side. We conclude from our patients that robotic-assisted percutaneous scaphoid fixation is feasible, safe and accurate, and is a satisfactory method for treating these injuries. Level of evidence: IV.

The Use of the Proximal Hamate as an Autograft for Proximal Pole Scaphoid Fractures: Clinical Outcomes and Biomechanical Implications

Scaphoid proximal pole fractures remain a surgical challenge because of high propensity for nonunion, osteonecrosis, and ultimately carpal collapse. Options for management of nonsalvageable proximal pole fractures include non-vascularized bone grafts, vascularized pedicled bone grafts, free vascularized bone flaps, and rib cartilage grafts. The proximal pole of the hamate can also serve as a replacement arthroplasty in the setting of proximal pole scaphoid nonunions with collapse, bone loss, and/or osteonecrosis. This novel graft addresses shortcomings of other graft choices by providing a local structural autograft solution with minimal donor site morbidity, correcting carpal collapse, reconstructing the scapholunate ligament, and mitigating the need for microvascular anastomosis.

Computer-assisted Surgery for Scaphoid Fracture

The computer-assisted surgery (CAS) has significantly improved the accuracy, reliability and outcomes of traumatic, spinal, nerve surgery and many other operations with a less invasive way. The application of CAS for scaphoid fractures remains experimental. The related studies are scanty and most of them are cadaver researches. Some intrinsic defects from the registration procedure, scan and immobilization of limbs may inevitably result in deviations. Some deviations become more obvious with operations of small bones (such as scaphoid) although they are acceptable for spine and other orthopedic surgeries. We reviewed the current literatures on the applications of CAS for scaphoid operation and summarized technical principles, scan and registration methods, immobilization of limbs and their outcomes. On the basis of the data, we analyzed the limitations of this technique and envisioned its future development.