OBJECTIVE: Scaphoid fractures in patients and assessment of healing using PCD-CT have, as far as we know, not yet been studied. Therefore, the aim was to compare photon counting detector CT (PCD-CT) with energy integrating detector CT (EID-CT) in terms of fracture visibility and evaluation of fracture healing.
METHODS: Eight patients with scaphoid fracture were examined with EID-CT and PCD-CT within the first week post-trauma, and with additional scans at 4, 6 and 8 weeks. Our clinical protocol for wrist examination with EID-CT was used (CTDIvol 3.1 ± 0.1 mGy, UHR kernel Ur77). For PCD-CT matched radiation dose, reconstruction kernel Br89. Quantitative analyses of noise, CNR, trabecular and cortical sharpness, and bone volume fraction were conducted. Five radiologists evaluated the images for fracture visibility, fracture gap consolidation and image quality, and rated their confidence in the diagnosis.
RESULTS: The trabecular and cortical sharpness were superior in images obtained with PCD-CT compared with EID-CT. A successive reduction in trabecular bone volume fraction during the immobilized periods was found with both systems. Despite higher noise and lower CNR with PCD-CT, radiologists rated the image quality of PCD-CT as superior. The visibility of the fracture line within 1-week post-trauma was rated higher with PCD-CT as was diagnostic confidence, but the subsequent assessments of fracture gap consolidation during healing process and the confidence in diagnosis were found equivalent between both systems.
CONCLUSIONS: PCD-CT offers superior visibility of bone microstructure compared with EID-CT. The evaluation of fracture healing and confidence in diagnosis were rated equally with both systems, but the radiologists found primary fracture visibility and overall image quality superior with PCD-CT.

OBJECTIVE: To demonstrate the potential of low-dose ultra-high-resolution CT (UHRCT) images to generate high-quality radiographic images on extremity phantoms and to estimate the radiation dose required for this.
METHODS: A hand and knee phantom containing real human bones was imaged on an UHRCT scanner at full-dose, half-dose, and quarter-dose levels using a high-resolution extremity protocol. The raw data was reconstructed using both filtered back projection (FBP) and an iterative reconstruction algorithm (AIDR3D). Using custom designed software, each CT volume data set was converted to attenuation coefficients, and then a synthesized radiograph (synDX) was generated by forward projecting the volume data sets from a point source onto a 2D synthetic detector. The signal-to-noise ratio (SNR) was measured in the synDXs across all dose levels and the root-mean-squared error (RMSE) was computed with the FD synDXs as the reference.
RESULTS: The proposed workflow generates high-quality synDXs at any arbitrary angle. For FBP, the SNR largely tracked with the radiation dose levels for both the knee and hand phantoms. For the knee phantom, iterative reconstruction provided a 6.1% higher SNR when compared to FBP. The RMSE was overall higher for the lowest dose levels and monotonically decreased with increasing dose. No substantial differences were observed qualitatively in the visualization of skeletal detail of the phantoms.
CONCLUSIONS: The fine detail provided by UHRCT acquisitions of extremities facilitates the ability to generate quality radiographs, potentially eliminating the need for additional scanning on a conventional digital radiography system.

OBJECTIVE: 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.
CONCLUSIONS: 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.

BACKGROUND: Numerous studies have been published on the use of 1,2-intercompartmental supra-retinacular artery (ICSRA) as a pedicled vascularised bone graft (PVBG) in scaphoid fracture non-union, however, only very few studies have reported their results of 2,3-ICSRA. The aim of this study was to compare the patient-rated outcome scores between these two PVBGs in proximal pole scaphoid fracture non-union.
METHODS: Nineteen patients who underwent surgery for scaphoid non-union between 2017 and 2021 at a single institution were recruited retrospectively in this study. All patients were operated by a one senior orthopaedic surgeon. A mailed questionnaire with the modified mayo wrist (MMW) and the patient rated wrist evaluation (PRWE) scores were sent to the patients.
RESULTS: All patients were males with a mean age of 22.5 years. There was no statistically significant difference in the PRWE score between the two PVBGs. However, a statistically significant difference was found in the MMW score, with the 1,2-ICSRA PVBG having better scores.
CONCLUSIONS: Despite the 2,3-ICSRA having a longer arc of rotation, longer nutrient arteries, and is technically easier to incorporate in a PVBG, when compared with the 1,2-ICSRA it did not result in better patient-rated outcome scores.

Assessment of scaphoid fracture union on computed tomography scans is not currently standardized. We investigated the extent of scaphoid waist fracture union required to withstand physiological loads in a finite element model, based on a high-resolution CT scan of a cadaveric forearm. For simulations, the scaphoid waist was partially fused at the radial and ulnar sides. A physiological load of 100 N was transmitted to the scaphoid and the minimal amount of union to maintain biomechanical stability was recorded. The orientation of the fracture plane was varied to analyse the effect on biomechanical stability. The results indicate that the scaphoid is more prone to re-fracture when healing occurs on the ulnar side, where at least 60% union is required. Union occurring from the radial side can withstand loads with as little as 25% union. In fractures more parallel to the radial axis, the scaphoid seems less resistant on the radial side, as at least 50% union is required. A quantitative CT scan analysis with the proposed cut-off values and a consistently applied clinical examination will guide the clinician as to whether mid-waist scaphoid fractures can be considered as truly united.

BACKGROUND: Allograft bone screws are rarely described for the fixation of the scaphoid. When fresh fractures are treated, metal screws are mainly used; when pseudarthrosis is the indication, plates in combination with vascularized or non-vascularized bone grafts are mainly used. The necessity of metallic screw removal is under debate, but it is mandatory for plates because of movement restrictions due to the plate. The use of biomaterials in scaphoid fracture fixation was described as leading to union rates of between 64 and 100%. Brcic showed the incorporation of an allogeneic cortical bone screw at 10 weeks postoperative, along with revascularization and stable osteosynthesis with primary bone healing, without any signs of immunological rejection. The purpose of this retrospective study was to explore the results obtained using an allogenic cortical bone screw (Shark Screw®) in patients with fresh scaphoid fracture fixation and pseudarthroses with respect to union rates and time to union.
METHODS: We retrospectively analyzed 75 patients: 31 with fresh fractures and 44 pseudarthrosis patients. The Shark Screw® was used for the fixation of the scaphoid in the fresh-fracture and pseudarthrosis patients. We evaluated the union rate, complication rate and time to union.
RESULTS: Using the human allogeneic cortical bone screw for scaphoid fracture fixation led to a high union rate (94-96%). There were two nonunions in the fresh fracture group and two nonunions in the pseudarthrosis group. The complication rate was 1.3% (1 patient). Median time to union was 16, 18 and 29 weeks for the fresh-fracture, pseudarthrosis and delayed-union patients, respectively. The treatment of fresh scaphoid fractures and pseudarthroses showed similar union rates to those described in the literature, uses a shorter and less invasive surgical method with no need for hardware removal, and has a low complication rate.
CONCLUSIONS: Using the human allogenic cortical bone screw (Shark Screw®) led to similar union rates in fresh fractures-but better union rates in pseudarthrosis patients-compared to those presented in the literature for other scaphoid fracture fixation techniques, and it enabled a short and low-invasive procedure without any donor site morbidity and without the necessity to remove the hardware in a second surgery. The pseudarthrosis patient group showed a particularly strong benefit from this new procedure. The physiological bone metabolism remodels the cortical bone screw without scars.
METHODS: III: retrospective cohort study, therapeutic investigation of a treatment.

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.
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.
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.
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.
Therapeutic II.

BACKGROUND: 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.
METHODS: 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.
CONCLUSIONS: 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.

OBJECTIVE: Studies exploring the epidemiological characteristics of scaphoid fracture nonunion are important to understand the causes and lead to effective prevention strategy. However, such knowledge is limited especially in China. This study aims to reveal the clinical and epidemiological features of scaphoid fracture nonunion in Chinese patients.
METHODS: This was a retrospective study, which was based on patients with scaphoid fracture nonunion treated in a Chinese national orthopedic referral center from 1 August 2009 to 1 August 2020. The basic demographic and clinical characteristics, including gender, age at diagnosis of scaphoid fracture nonunion, dominant hand, the location of fracture, the side, the causes of the injury, age of the injury, age of the treatment for scaphoid fracture nonunion, and the delay period, were retrieved from the medical records. The patients were divided into a non-delay group and a delay group based on whether they had visited the doctor within 1 month after the injury. Scaphoid fracture was classified into the proximal, waist, and distal fractures according to the location. The t-test or Mann-Whitney U test was used to compare the difference between groups when the dependent variable is continuous, while a chi-square test was used when the dependent variable is categorical.
RESULTS: A total of 363 patients were included in this study. The mean age at the diagnosis of scaphoid fracture nonunion was 32 (ranging from 14 to 78). Waist fracture nonunion (76.5%) was most common. Among the 169 patients who sought medical care within 1 month after the injury (non-delay group), more than half (90 cases) were misdiagnosed. 23 cases could not recall the injury, so the time of delay could not be determined. Among the 171 patients who did not seek medical care for acute injury (delay group), the average time was 52 months between the initial injury and the treatment. The proportion of waist nonunions was higher among patients in the delay group than that in the non-delay group.
CONCLUSIONS: Nonunion of scaphoid fracture is caused mainly by delayed treatment and misdiagnosis in China, suggesting that timely treatment and improved diagnosis could lower the prevalence. The fracture location may be a factor contributing to the delaying of seeking medical care.

The purpose of this study was to assess the efficiency, safety, and accuracy of cannulated screw fixation using a robot-assisted method compared with a traditional percutaneous freehand method.
This retrospective clinical study included 18 patients with scaphoid fracture who underwent cannulated screw fixation by robot-assisted technique or traditional percutaneous freehand technique from June 2018 to June 2020. All patients were divided into the robot-assisted group (9 patients) or the traditional surgery group (9 patients). The operation time, blood loss, number of intra-operative fluoroscopies, fracture healing time, Mayo wrist function score, and screw implantation accuracy were recorded in the two groups.
The average age of the robot-assisted group was 37.9 ± 10.6 years (with a range of 30 to 52 years), there were eight males and one female, and there were six cases of scaphoid fracture on the right side and three on the left side. The average pre-operative time was 2.8 ± 0.7 days (ranging from 1 to 3 days). The average age of the traditional surgery group was 31.6 ± 6.8 years (with a range of 20 to 45 years), there were eight males and one female, and there were five cases of scaphoid fracture on the right side and four on the left side. The average pre-operative time was 2.1 ± 0.8 days (with a range of 2 to 4 days). The number of intra-operative fluoroscopies was 24.4 ± 3.5 in the traditional surgery group, whereas it was only 10.1 ± 1.9 in the robot-assisted group, which was significantly lower (P < 0.05). The average operation time of the traditional operation group was 48.4 ± 12.2 min, and that of the robot-assisted group was 32.6 ± 4.2 minutes, which was significantly shorter (P < 0.05). The angles between the actual screw position and the central axis of the scaphoid on both the coronal and sagittal post-operative CT images were 8.3° ± 2.3° and 8.8° ± 1.6° for the traditional operation group and 3.8° ± 0.8° and 4.3° ± 1.2° for the robot-assisted group, so the accuracy of the robot-assisted group was significantly higher (P < 0.05). There were no significant differences between the two groups in wrist function recovery or fracture healing time.
Robot-assisted treatment of scaphoid fracture is more accurate than traditional freehand technology, with shorter operation time and fewer intra-operative fluoroscopies. There is no difference between the two surgical techniques in intra-operative bleeding, post-operative fracture healing, or functional recovery. Robot-assisted surgery is a safe, effective, and accurate method for treating scaphoid fracture.