[Accuracy and clinical efficacy of robot-assisted transiliac-transsacral screw placement for posterior pelvic ring fractures].

OBJECTIVE: To explore accuracy and clinical effect of robot-assisted implantation of sacroiliac penetrating screw in orthopedic surgery for posterior pelvic ring fracture. METHODS: The clinical data of 24 patients with posterior pelvic ring fracture treated with robot-assisted sacroiliac penetration screws from August 2022 to August 2023 were retrospectively analyzed, including 10 males and 14 females; aged from 21 to 73 years old with an average of (49.29±14.48) years old;according to Tile pelvic fractures, 13 patients were type B and 11 were type C. The effect of screw placement was evaluated according to Gras criteria based on postoperative CT scan results. At the final follow-up, fracture healing was evaluated according to Matta score, and functional recovery was evaluated by Majeed score. RESULTS: All patients were followed up for 3 to 13 months with an average of (6.00±3.28) months. Totally 36 sacroiliac penetrating screws, 18 S1 penetrating screws, 18 S2 penetrating screws were inserted, a total of 29 were excellent and 7 good according to Gras standard. Screw adjustment times was 0.00 (0.00, 0.75) times. At the final follow-up, Matta score was excellent in 18 patients, 5 good and 1 moderate, and the maximum displacement distance was 2.55 (0.00, 5.65) mm. Majeed score was 84.37±8.38, 15 patients were excellent, 7 good and 2 moderate. CONCLUSION: Robot could accurately and safely assist in the placement of sacroiliac joint screws for the treatment of posterior pelvic ring fractures, and promote postoperative functional recovery of patients.

L4 fixation is not necessary in L5-Iliac spinopelvic fixation after trauma, but coadjutant transilio-transsacral fixation is.

INTRODUCTION: Spinopelvic dissociation (SPD) is a severe injury characterized by a discontinuity between the spine and the bony pelvis consisting of a bilateral longitudinal sacral fracture, most of the times through sacral neuroforamen, and a horizontal fracture, usually through the S1 or S2 body. The introduction of the concept of triangular osteosynthesis has shown to be an advance in the stability of spinopelvic fixation (SPF). However, a controversy exists as to whether the spinal fixation should reach up to L4 and, if so, it should be combined with transiliac-transsacral screws (TTS). OBJECTIVE: The purpose of this study is to compare the biomechanical behavior in the laboratory of four different osteosynthesis constructs for SPD, including spinopelvic fixation of L5 versus L4 and L5; along with or without TTS in both cases. MATERIAL AND METHODS: By means of a formerly described method by the authors, an unstable standardized H-type sacral fracture in twenty synthetic replicas of a male pelvis articulated to the lumbar spine, L1 to sacrum, (Model: 1300, SawbonesTM; Pacific Research Laboratories, Vashon, WA, USA), instrumented with four different techniques, were mechanically tested. We made 4 different constructs in 5 specimen samples for each construct. Groups: Group 1. Instrumentation of the L5-Iliac bones with TTS. Group 2. Instrumentation of the L4-L5-Iliac bones with TTS. Group 3. Instrumentation of L5-Iliac bones without TTS. Group 4: Instrumentation of L4-L5-Iliac bones without TTS. RESULTS AND CONCLUSIONS: According to our results, it can be concluded that in SPD, better stability is obtained when proximal fixation is only up to L5, without including L4 (alternative hypothesis), the addition of transiliac-transsacral fixations is essential.

[Early effectiveness of computer navigation system-assisted transiliac-transsacral screws placement for posterior pelvic ring injuries].

Objective: To investigate the early effectiveness of transiliac-transsacral screws internal fixation assisted by augmented reality navigation system HoloSight (hereinafter referred to as "computer navigation system") in the treatment of posterior pelvic ring injuries. Methods: A retrospective analysis was made in the 41 patients with posterior pelvic ring injuries who had been treated surgically with transiliac-transsacral screws between June 2022 and June 2023. The patients were divided into navigation group (18 cases, using computer navigation system to assist screw implantation) and freehand group (23 cases, using C-arm X-ray fluoroscopy to guide screw implantation) according to the different methods of transiliac-transsacral screws placement. There was no significant difference in gender, age, body mass index, causes of injuries, Tile classification of pelvic fracture, days from injury to operation, usage of unlocking closed reduction technique between the two groups ( P>0.05). The time of screw implantation, the fluoroscopy times, the guide wire adjustment times of each screw, and the incidence of complications were recorded and compared between the two groups. The position of the transiliac-transsacral screw was scanned by CT within 2 days after operation, and the position of the screw was classified according to Gras standard. Results: The operation was successfully completed in both groups. The time of screw implantation, the fluoroscopy times, and the guide wire adjustment times of each screw in the navigation group were significantly less than those in the freehand group ( P<0.05). There were 2 cases of incision infection in the freehand group, and the incision healed by first intention after active dressing change; there was no screw-related complication in the navigation group during operation and early period after operation; the difference in incidence of complications between the two groups (8.7% vs. 0) was not significant ( P=0.495). According to the Gras standard, the screw position of the navigation group was significantly better than that of the freehand group ( P<0.05). Conclusion: Compared with the traditional freehand method, the computer navigation system assisted transiliac-transsacral screws internal fixation in the treatment of posterior pelvic ring injuries has advantages of improving the accuracy of screw implantation and reducing radiation damage and the time of screw implantation.

Nonoperative management of minimally displaced lateral compression type 1 (LC1) injuries with comminuted rami fractures is associated with late displacement.

PURPOSE: Rami comminution has been found to be predictive of lateral compression type 1 (LC1) injury instability on examination under anesthesia (EUA) and lateral stress radiographs (LSR). The purpose of this study was to evaluate how rami comminution and subsequent operative vs. nonoperative management impact the late displacement of these injuries. METHODS: Retrospective review of a prospectively collected LC1 database was performed to identify all patients with minimally displaced LC1 injuries (< 1 cm) and follow-up radiographs over a four-year period (n = 125). Groups were separated based on the presence of rami comminution and subsequent management, including rami comminution/operative (n = 49), rami comminution/nonoperative (n = 54), and no comminution/nonoperative (control group, n = 22). The primary outcome was late fracture displacement, analyzed as both a continuous variable and as late displacement ≥ 5 mm. RESULTS: As a continuous variable, late fracture displacement was lower in the comminuted rami/operative group as compared to the comminuted rami/nonoperative group (PD: -3.0 mm, CI: -4.8 to -1.6 mm, p = 0.0002) and statistically non-different from control. Late displacement ≥ 5 mm was significantly more prevalent in the comminuted rami/nonoperative group than in the comminuted rami/operative and no comminution/nonoperative groups (control)(PD: -33.9%, CI: -49.0% to -16.1%, p = 0.0002 and PD: -30.0%, CI: -48.2% to -6.5%, p = 0.02, respectively). CONCLUSION: Late fracture displacement was greatest in the group with rami comminution/nonoperative management. Rami comminution, which has been previously associated with dynamic displacement on EUA and LSR, is also associated with a higher incidence of late displacement when managed nonoperatively. LEVEL OF EVIDENCE: Level III, prognostic retrospective cohort study.

Early effectiveness of computer navigation system-assisted transiliac-transsacral screws placement for posterior pelvic ring injuries / 中国修复重建外科杂志

OBJECTIVE@#To investigate the early effectiveness of transiliac-transsacral screws internal fixation assisted by augmented reality navigation system HoloSight (hereinafter referred to as "computer navigation system") in the treatment of posterior pelvic ring injuries.@*METHODS@#A retrospective analysis was made in the 41 patients with posterior pelvic ring injuries who had been treated surgically with transiliac-transsacral screws between June 2022 and June 2023. The patients were divided into navigation group (18 cases, using computer navigation system to assist screw implantation) and freehand group (23 cases, using C-arm X-ray fluoroscopy to guide screw implantation) according to the different methods of transiliac-transsacral screws placement. There was no significant difference in gender, age, body mass index, causes of injuries, Tile classification of pelvic fracture, days from injury to operation, usage of unlocking closed reduction technique between the two groups ( P>0.05). The time of screw implantation, the fluoroscopy times, the guide wire adjustment times of each screw, and the incidence of complications were recorded and compared between the two groups. The position of the transiliac-transsacral screw was scanned by CT within 2 days after operation, and the position of the screw was classified according to Gras standard.@*RESULTS@#The operation was successfully completed in both groups. The time of screw implantation, the fluoroscopy times, and the guide wire adjustment times of each screw in the navigation group were significantly less than those in the freehand group ( P<0.05). There were 2 cases of incision infection in the freehand group, and the incision healed by first intention after active dressing change; there was no screw-related complication in the navigation group during operation and early period after operation; the difference in incidence of complications between the two groups (8.7% vs. 0) was not significant ( P=0.495). According to the Gras standard, the screw position of the navigation group was significantly better than that of the freehand group ( P<0.05).@*CONCLUSION@#Compared with the traditional freehand method, the computer navigation system assisted transiliac-transsacral screws internal fixation in the treatment of posterior pelvic ring injuries has advantages of improving the accuracy of screw implantation and reducing radiation damage and the time of screw implantation.

The combination of intraoperative CT navigation and C-arm fluoroscopy for INFIX and percutaneous TITS screw placement in the treatment of pelvic ring injury: technical note.

BACKGROUND: The subcutaneous screw rod system, commonly known as the internal pelvic fixator (INFIX), is useful in managing unstable pelvic ring fractures. Conventional INFIX and transiliac-transsacral (TITS) screw techniques are performed using C-arm fluoroscopy. There have been problems with medical exposure and screw insertion accuracy with these techniques. This work describes new INFIX and TITS techniques using intraoperative computed tomography (CT) navigation and C-arm fluoroscopy for pelvic ring fracture. METHODS: A typical case is presented in this study. An 86-year-old woman suffered from an unstable pelvic ring fracture due to a fall from a height. INFIX and TITS screw fixation with intraoperative CT navigation were selected to optimize surgical invasiveness and proper implant placement. RESULTS: The patient was placed in a supine position on a Jackson table. An intraoperative CT navigation was imaged, and screws were inserted under the navigation. Postoperative X-rays and CT confirmed that the screw was inserted correctly. This technique was less invasive to the patient and had little radiation exposure to the surgeon. Rehabilitation of walking practice was started early after the surgery, and she was able to walk with the assistance of a walker by the time of transfer. CONCLUSIONS: The technique employed in our case study has the cumulative advantages of safety, accuracy, and reduced radiation exposure, together with the inherent advantages of functional outcomes of previously reported INFIX and TITS screw techniques. Further experience with this approach will refine this technique to overcome its limitations and facilitate its wider use.

Three-dimensional morphometry of the first two sacral segments and its impact on safe transiliac-transsacral screw placement.

INTRODUCTION: Percutaneous screw fixation of the posterior pelvic ring is a popular technique to treat unstable pelvic ring lesions. This technique is practicable in both, the high-energy pelvic ring fractures, mostly in the young population as well as the osteoporotic fractures in the elderly. Risk of the transiliac-transsacral screw positioning is that the critical area of nerve root exit has to be passed twice. For secure screw placement, without causing iatrogenic neurovascular injuries, the knowledge of distances to the narrowest areas is essential. Purpose of this anatomical study was to examine the optimal intraosseous screw placement for the first two sacral segments. MATERIAL/METHODS: Images of uninjured pelves from 50 patients (64-line CT scanner) were evaluated. Then virtual transiliac-transsacral srews were positioned into the first two sacral segments. The distance from the screws' entrance points at the ilium's alar bone to the narrowest portion of the whole pedicle as well as the height and width in this area were measured. Descriptive statistics were used and gender related differences were evaluated using student T-test. RESULTS: For the first sacral segment the distance to the narrowest zone amounted in mean 62.75 mm, respectively 63.31 mm, depending on the selected way of measurement. For the second segment the mean distance to the neuroforamina was on average 50.61 mm, respectively 51.54 mm. The average height in S1 measured 25.88 mm and the average width 25.49 mm. The average height for S2 was 17.54 mm and the average width 17.61 mm. We could not find any statistically significant gender correlation for the measured distances. CONCLUSION: Results of this anatomical study may help in performing a safe surgical procedure.

A useful intraoperative technique for transiliac-transsacral screws: a point-to-point coaxial guide apparatus.

BACKGROUND: The transiliac-transsacral screw placement is a clinical challenge for surgeons. This study explored a point-to-point coaxial guide apparatus assisting the transiliac-transsacral screw insertion and aimed to investigate the feasibility and accuracy of the guide apparatus in the treatment of posterior ring unstable pelvic fracture compared with a free-hand technique. METHODS: A retrospective study was performed to evaluate patients treated with transiliac-transsacral screws assisted by the point-to-point coaxial guide apparatus or free-hand technique. The intraoperative data of operative time and radiation exposure times were recorded. Postoperative radiographs and CT scans were performed to scrutinize the accuracy of screws position. The quality of the postoperative fracture reduction was assessed according to Matta radiology criteria. The pelvic function was assessed according to the Majeed scoring criteria at 6 months postoperatively. RESULTS: From July 2017 to December 2019, a total of 38 patients were included in this study, 20 from the point-to-point guide apparatus group and 18 from the free-hand group. There were no significant differences between the two groups in gender, age, injury causes, pelvic fracture type, screws level, and follow-up time (P > 0.05). The average operative time of the guide apparatus group for each screw was significantly less than that in the free-hand group (25.8 ± 4.7 min vs 40.5 ± 5.1, P < 0.001). The radiation exposure times were significantly lower in the guide apparatus group than that in the free-hand group (24.4 ± 6.0 vs 51.6 ± 8.4, P < 0.001). The intraosseous and juxtacortical rate of screw placement (100%) higher than in the free-hand group (94.4%). CONCLUSION: The point-to-point coaxial guide apparatus is feasible for assisting the transiliac-transsacral screw in the treatment of posterior unstable pelvic fractures. It has the advantages of simple operation, reasonable design and no need for expensive equipment, and provides an additional surgical strategy for the insertion of the transiliac-transsacral screw.

Assessment of osseous corridor for transiliac-transsacral screws and clinical applications: Computational simulation study.

BACKGROUND: Transiliac-transsacral (TITS) screw fixation might be necessary in some cases involving the vertical shearing injuries with transforaminal fracture and bilateral posterior ring injuries. However, the possibility of S1 TITS screw should be preoperatively assessed because the pelvic ring injuries with sacral dysmorphism had the insufficient osseous corridors. HYPOTHESIS: AxWS2 may predict the possibility of TITS screw fixation and be used as the new indicator to discriminate the sacral dysmorphism. MATERIALS & METHODS: The conventional CT images of eighty-two cadaveric pelvis imported into Mimics® software to reconstruct three-dimensional (3D) models. A 7.0 mm-sized screw was processed into a 3D model using a 3D-sensor at actual size and virtually implanted as S1 and S2 TITS screw using Mimics® software. The cortical violation around screw path was evaluated using 3D biplanar and conventional CT images. The osseous corridor widths around TITS screws were measured in the axial plane images and defined as AxWS1 and AxWS2, respectively. RESULTS: Despite no cortical violation in S2 of all models, cortical violation of S1 TITS screw was found in 20 models. Of them, 14 models (impossible models) were identified in the 3D biplanar images, and all 20 models (CT-violation models) were identified only in CT axial plane images. AxWS1 was<7mm in the impossible models and<9.0mm in the CT-violation models. AxWS2 negatively correlated with AxWS1 (R -0.450, p<0.01). By receiver operating characteristic curve analysis to identify the CT-violation model using AxWS2, the cut-off value of AxWS2 was 13.32mm (sensitivity 0.70, specificity 0.70). DISCUSSION: By using AxWS2, the possibility of S1 TITS screw fixation could be predicted and safely placed without cortical violation, if AxWS2 was less than 13mm. Considering the negative relationship with AxWS1, AxWS2 should be used as a new indicator to predict safe S1 TITS screw fixation. LEVEL OF EVIDENCE: III, controlled laboratory study.

Comparison between posterior sacral plate stabilization versus minimally invasive transiliac-transsacral lag-screw fixation in fractures of sacrum: a single-centre experience.

PURPOSE: The sacrum is a mechanical nucleus working as the base for the spinal column, as well as the keystone of the pelvic ring. Thus, injuries of the sacrum can lead to biomechanical instability and nerve conduction abnormality. METHODS: The common classification is the Denis classification, but these fractures are often part of a lesion of the posterior pelvic ring and therefore the Tile classification is very useful. The goals of operative intervention are to reduce fracture fragments, protect neurological structures, and provide adequate stability for early mobilization. RESULTS: The stabilization of these injuries can be difficult even in a patient with adequate bone stock and concomitant medical comorbidities. The posterior-ring tension-band metallic plate and sacroiliac joint screw are two commonly used methods for posterior internal fixation of the pelvis. CONCLUSIONS: In this study, we evaluate the differences, in the treatment of sacral fractures, between the two techniques, revising the literature and our experience.

Reduction and temporary stabilization of Tile C pelvic ring injuries using a posteriorly based external fixation system.

Tile C pelvic ring injuries are challenging to manage even in the most experienced hands. The majority of such injuries can be managed using percutaneous reduction techniques, and the posterior ring can be stabilized using percutaneous transiliac-transsacral screw fixation. However, a subgroup of patients present with inadequate bony corridors, significant sacral zone 2 comminution or significant lateral/vertical displacement of the hemipelvis through a complete sacral fracture. Percutaneous strategies in such circumstances can be dangerous. Those patients may benefit from prone positioning and open reduction of the sacral fracture with fixation through tension band plating or lumbo-pelvic fixation. Soft tissue handling is critical, and direct reduction techniques around the sacrum can be difficult due to the complex anatomy and the fragile nature of the sacrum making clamp placement and tightening a challenge. In this paper, we propose a mini-invasive technique of indirect reduction and temporary stabilization, which is soft tissue friendly and permits maintenance of reduction during definitive fixation surgical.

Computational simulation study on ilio-sacral screw fixations for pelvic ring injuries and implications in Asian sacrum.

OBJECTIVES: Despite a high possibility of technique-related complications, ilio-sacral (IS) screw fixation is the mainstay of operative management in posterior pelvic ring injuries. We aimed to make IS screw trajectory with fully intraosseous path that was optimal and consistent, and confirm the possibility of transiliac-transsacral (TITS) screw fixation in Asian sacrum. METHODS: Eighty-two cadaveric sacra (42 males and 40 females) were enrolled and underwent continuous 1.0-mm slice computed tomography (CT) scans. CT images were imported into Mimics® software to reconstruct three-dimensional model of the pelvis. To simulate IS screws, we inserted 7.0-mm-sized TITS cylinder for first (S1) and second (S2) sacral segment and 7.0-mm oblique cylinder for S1. TITS cylinder could not be inserted into S1 of 14 models (sacral variation models) but could be inserted into the S2 of all models. The actual length of virtual IS screws was measured, and anatomic features of safe zone (SZS2) including the area, horizontal distance (HDS2), and vertical distance (VDS2) were evaluated by the possibility of TITS screw fixation in the S1. RESULTS: When the oblique cylinder was directed toward the opposite upper corner of S1 at the level of the first foramen, there was no cortical violation regardless of sacral variation. The average length of TITS cylinder was 152.3 mm (range 127.9-178.2 mm) in S1 and 136.0 mm (range 97.8-164.1 mm) in S2, and for oblique cylinder it was 99.2 mm (range 82.4-132.2 mm). The average VDS2, HDS2, and the area of SZS2 were 15.5 mm (range 8.7-24.4 mm), 18.3 mm (range 12.7-26.6 mm), and 221.1 mm2 (range 91.1-386.7 mm2), respectively. The VDS2 and SZS2 of sacral variation were significantly higher than those of normal (both p = 0.001). CONCLUSIONS: Considering the high variability of the S1, it is better to direct the IS screw trajectory toward the opposite upper corner of the S1 at the level of first sacral foramen. If a TITS screw is needed, the transverse fixation for the S2 could be performed alternatively due to its sufficient osseous site even in Asian sacrum.