Retrograde Screw Research Articles

Finite Element Analysis of Percutaneous Anterograde and Retrograde Screws in the Treatment of Superior Rami Pubis Fracture

PurposeThis study aims to evaluate the biomechanical characteristics of percutaneous antegrade and retrograde screws in treating superior pubic rami fractures in zone II, employing finite element analysis. It provides a theoretical basis for the treatment of the superior rami of pubis zone II fracture.MethodsThe software of Mimics and 3-Matic were utilized for reconstructing a fracture model of the superior pubic rami in zone II. Percutaneous screw implantation was simulated for treatment. Material properties were assigned using Mimics, and Ansys software was employed to simulate forces on the S1 vertebral endplate under a 500 N load in a standing posture. Mechanical stability was assessed by comparing these simulations.Results(1) Displacement and stress variations in the pubic bone and screws were consistent across the model and on the fracture site, whether the fracture was in zone I or zone II. However, in zone III, the displacement and stress experienced by the screws were markedly higher than those in zones I and II. (2) When employing an antegrade screw to simulate treatment of a superior pubic rami fracture in zone II, the maximum displacement and stress recorded were 0.88 mm and 15.53 MPa, respectively. Conversely, the use of a retrograde screw for treating a superior pubic rami fracture yielded a maximum displacement of 0.59 mm and stress of 5.51 MPa.ConclusionThe biomechanical analysis suggests that for zone II superior pubic rami fractures, where the fracture line is no more than 70 mm from the insertion point (encompassing zones I and II fractures), the use of retrograde screw implantation is preferable.

Maintenance of acetabular correction following PAO: a multicenter study comparing stainless-steel and titanium screws.

Stainless-steel screws are commonly used for fragment fixation during periacetabular osteotomy (PAO) at our institutions. Titanium is reserved for patients with documented nickel allergies. Titanium screws possess a significantly lower Young's modulus than stainless steel and, therefore, potentially less resistance to physiologic loading. Thus, we hypothesized that the use of titanium screws might be associated with changes in acetabular correction prior to healing. The aim of this study was to compare the maintenance of acetabular correction following PAO using stainless-steel or titanium screws. A documented nickel allergy was confirmed with an allergy specialist. Patients' age at surgery, gender and BMI were collected. The lateral center-edge angle of Wiberg (LCEA), medial center-edge angle (MCEA), anterior wall index (AWI), posterior wall index (PWI) and Tönnis angle were measured. The delta value for radiographic parameters was calculated as the difference between values immediately post-operation and at 6 months post-operation. Only age at surgery (P < 0.001) and the pre-operative LCEA (P = 0.013) were significantly different between groups (Tables I and II). The remaining pre- and post-operative radiological measurements were similar (Table II). Comparison of delta values at 6 months follow-up indicated no significant differences between screw types (Table III). No patients in the titanium group had a trans-iliac retrograde screw included in their construct (P = 0.003). All patients healed from their osteotomies. The use of titanium screws in patients with an allergy to nickel was not associated with differences in acetabular correction or the rate of osseous union rates despite its lower inherent mechanical properties.

Antegrade Posterior Column Acetabulum Fracture Screw Fixation via Posterior Approach: A Biomechanical Comparative Study.

Background and Objectives: Minimally invasive surgeries for acetabulum fracture fixation are gaining popularity due to their known advantages versus open reduction and internal fixation. Antegrade or retrograde screw fixation along the long axis of the posterior column of the acetabulum is increasingly applied in surgical practice. While there is sufficient justification in the literature for the application of the anterior approach, there is a deficit of reports related to the posterior approach. The aim of this study was to evaluate the biomechanical competence of posterior column acetabulum fracture fixation through antegrade screw placement using either a standard cannulated screw or a cannulated compression headless screw (CCHS) via posterior approach. Materials and Methods: Eight composite pelvises were used, and a posterior column acetabulum fracture according to the Letournel Classification was simulated on both their left and right sides via an osteotomy. The sixteen hemi-pelvic specimens were assigned to two groups (n = 8) for either posterior column standard screw (group PCSS) or posterior column CCHS (group PCCH) fixation. Biomechanical testing was performed by applying steadily increased cyclic load until failure. Interfragmentary movements were investigated by means of motion tracking. Results: Initial stiffness demonstrated significantly higher values in PCCH (163.1 ± 14.9 N/mm) versus PCSS (133.1 ± 27.5 N/mm), p = 0.024. Similarly, cycles and load at failure were significantly higher in PCCH (7176.7 ± 2057.0 and 917.7 ± 205.7 N) versus PCSS (3661.8 ± 1664.5 and 566.2 ± 166.5 N), p = 0.002. Conclusion: From a biomechanical perspective, CCHS fixation demonstrates superior stability and could be a valuable alternative option to the standard cannulated screw fixation of posterior column acetabulum fractures, thus increasing the confidence in postoperative full weight bearing for both the patient and treating surgeon. Whether uneventful immediate postoperative full weight bearing can be achieved with CCHS fixation should primarily be investigated in further human cadaveric studies with a larger sample size.

Distal Metaphyseal Ulnar Shortening Osteotomy Fixation: A Biomechanical Analysis

Ulnar shortening osteotomy can be used to treat ulnar impaction syndrome and other causes of ulnar wrist pain. Distal metaphyseal ulnar shortening osteotomy (DMUSO) is one technique that has been proposed to reduce the complications seen with a diaphyseal USO or a wafer resection. However, to our knowledge, the optimal fixation construct for DMUSO has not been studied. We sought to characterize the biomechanical stiffness and rotational stability of different DMUSO constructs. A DMUSO was performed on 40 human cadaveric ulnas using 4 different fixation constructs (10 specimens per group): one 3.0 mm antegrade screw; two 2.2 mm antegrade screws; one 3.0 mm retrograde screw; and two 2.2 mm retrograde screws. Biaxial testing using axial load and cyclical axial torque was performed until failure, defined as 10° of rotation or 2 mm displacement. Specimens were assessed for stiffness at failure. Bone density was assessed using the second metacarpal cortical percentage. Bone density was similar between all 4 testing groups. Of the 4 groups, the 2 antegrade screw group exhibited the highest rotational stiffness of 232 ± 102 Nm/deg. In paired analysis, this was significantly greater than 1 retrograde screw constructs. In multivariable analysis, 2-screw constructs were significantly stiffer than 1 screw and antegrade constructs were significantly stiffer than retrograde. Maximum failure torque did not differ with orientation, but 2 screws failed at significantly higher torques. Using 2 screws for DMUSO fixation constructs may provide higher stiffness and maximum failure torque, and antegrade screw constructs may provide more stiffness than retrograde constructs. Antegrade screw fixation using 2 screws may provide the strongest construct for DMUSO. Antegrade fixation may be preferred because it avoids violating the distal radioulnar joint capsule and articular surface of the ulna.

Clinical outcomes of percutaneous screw fixation of acetabular fracture: A minimally invasive procedure

ObjectiveOpen reduction with internal fixation is the surgical intervention of choice for acetabular fractures (AFs). Percutaneous screw fixation for AFs is a new procedure that is desirable because of the complex anatomy of the pelvis. In this study, we aimed to assess the functional outcomes, mobility, healing, and distal neurovascular abnormalities in patients who underwent percutaneous retrograde screw fixation. MethodsOur study included 36 patients with AFs treated with percutaneous screw fixation between January 2016 and June 2021. There were 18 cases with anterior column AF, 7 cases with transverse AF, and 11 cases with associated AF, 6 of which had a T-shaped AF. Frequencies and percentages were used to describe characteristics and clinical outcomes. Mean and standard deviation were used for continuous variables. SPSS version 23 (IBM Corporation, Armonk, NY, USA) was used for statistical analysis. ResultsThe average time to regain full mobility with full weight bearing was 12.9 ± 5.4 weeks, and approximately 11.1 ± 2.8 weeks was required for patients to be pain-free with satisfactory fracture healing. Only a minority (8.3%) of patients had abnormalities affecting the distal neurovascular system, and 11.1% experienced sexual dysfunction. Pain severity was assessed with a visual analogue scale. The average pain severity on the first and third post-operative days was 4 ± 2.4 and 3.8 ± 2.6, respectively. However, the average pain intensity before discharge was 1.7 ± 2.6. ConclusionPercutaneous screw fixation is the most efficient surgical choice for most pelvic/AFs.

Translated article] Comparison of three different minimally invasive intramedullary screw for proximal phalanx fractures. A biomechanical study

Background and objectivePhalangeal fractures are the most common hand fractures. In the last years, intramedullary compression screw (IMHCS) for instable transverse or short oblique proximal P1 fractures have been described. Although both anterograde (intraarticular or trans-articular) and retrograde IMHCS techniques have shown good results, no comparison between anterograde and retrograde screw in P1 fractures has been published. We sought to determine stability with retrograde IMHCS and anterograde IMHCS, both trans-articular and intra-articular technique, in a cadaveric transverse proximal P1 fracture model, at two different levels. Material and methodsWe performed a biomechanical study in 30 fresh-frozen human cadaveric P1 fracture model. Fracture was performed at 9-mm from the metacarpo-phalangeal (MCP) joint in 15 specimens, whereas it was done at 15mm in the other 15. In turn, in each group, five fractures were stabilised with an anterograde intra-articular IMHCS, five with anterograde trans-articular IMHCS and other five with retrograde IMHCS. ResultsAnterograde IMHCS fixation in 9-mm P1 fractures (both trans- and intra-articular technique, 62.74N and 70.86N, respectively) was found to be more stable than retrograde IMHCS one (32.72N) (p=0.022). Otherwise, retrograde IMHCS fixation was found to be more stable in more distal P1 fractures (90.52N retrograde vs. 57.64N trans-articular vs. 42.92N intra-articular; p=0.20). ConclusionsAnterograde IMHCS fixation in proximal transverse P1 bone cut in a cadaveric model provides more stability than retrograde IMHCS, while retrograde screw provides more stability when the bone cut is located more distal.

Outcomes of PIPA/DIPA with Retrograde Screw Fixation for Correction of Lesser Toe Deformities

Category: Lesser Toes; Midfoot/Forefoot Introduction/Purpose: Hammertoes and other lesser toe deformities represent extremely common foot problems, affecting nearly one-third of the general population. When surgery is indicated, correction of these deformities has traditionally been described using a PIP arthroplasty technique with a smooth, temporary Kirschner-wire for fixation. This method can produce excellent results, but there are well-described risks including deformity recurrence, secondary deformities, painful nonunion, and pin tract infections. Our goal is to describe a more modern technique that includes preparation and arthrodesis of both the PIP and DIP joints with intramedullary screw fixation. Methods: A retrospective chart review was conducted at one tertiary referral center of patients who underwent correction of lesser toe deformity between 2017 and 2021. Inclusion criteria were patient age greater than 18, use of the PIPA/DIPA technique with screw, and a minimum 10 weeks of follow up with radiographs. Charts were reviewed for patient demographics, comorbidities, preoperative characteristics, and postoperative complications. Our primary outcome variable was deformity correction achieved and maintained at minimum 10 weeks postoperatively based on both chart review and radiographs. Secondary outcomes included hardware failure, infection, vascular complication, screw removal for any reason, nonunion, and amputation. Results: 129 patients and 374 operative toes were identified on chart review and met inclusion criteria. Of these patients, 370 toes (98.9%) maintained deformity correction both clinically and radiographically at 10 weeks and did not undergo revision surgery. 17 toes (4.5%) required screw removal for any reason. 3 toes (0.8%) experienced deep infection, and 1 patient experienced superficial infection that resolved with oral antibiotic treatment. Furthermore, in addition to a concomitant deep infection, one toe experienced vascular compromise and required amputation. There were no symptomatic nonunions, and there were 7 (1.8%) asymptomatic nonunions as seen on radiographs. Conclusion: With respect to previously and classically described methods of lesser toe deformity correction, the PIPA/DIPA technique with a retrograde screw presents an acceptable and safe method for sustained deformity correction.

Biomechanical analysis of stability of joint depression calcaneal fractures: Fixation with locking compression plate alone compared with addition of supplemental oblique screw

PurposeThe standard treatment of calcaneus fractures is a lateral plate and screw construct. Patients at our institution have been treated with a lateral locking plate combined with one retrograde screw inserted in the oblique plane to allow immediate weight bearing. The purpose of this study was to determine whether addition of a oblique screw to a lateral plate construct increases stability. MethodsA Sanders 2B fracture (AO/OTA 83-C2) was created in 8 pairs (16 total specimens) of cadaveric feet. All were repaired using a lateral locking plate/screws construct. One specimen in each pair was chosen randomly to receive an additional oblique screw. The specimens were tested with cyclic load of up to 800 N. Movement at the fracture sites and subsidence of the talus were tracked with a three-dimensional video analysis system. ResultsTalar subsidence was not significantly affected by the presence of the additional oblique screw (p = 0.22). The sustentaculum fragment in the case of the screw repair moved 0.39 mm while the same fragment without the additional screw repair displaced 0.12 mm (p < 0.01). Two repairs with and one repair without the additional screw failed during longer-term cyclic loading. ConclusionThe two repair types were not statistically different in regards to talar subsidence. While statistical significance resulted in the comparison of sustentaculum fragment movement, the amount of movement did not reach a level of clinical relevance. This study demonstrated immediate stability and durability of the additional screw construct with high volume weight bearing loads.

Biomechanical analysis of Magic screw fixation for acetabular posterior column fracture

This study aims to analyze the biomechanical stability of Magic screw in the treatment of acetabular posterior column fractures by finite element analysis. A three-dimensional finite element model of the pelvis was established based on the computed tomography (CT) and magnetic resonance imaging (MRI) data of a volunteer and its effectiveness was verified. Then, the posterior column fracture model of the acetabulum was generated. The biomechanical stability of the four internal fixation models was compared. The 500 N force was applied to the upper surface of the sacrum to simulate human gravity. The maximum implant stresses of retrograde screw fixation, single-plate fixation, double-plate fixation and Magic screw fixation model in standing and sitting position were as follows: 114.10, 113.40 MPa; 58.93, 55.72 MPa; 58.76, 47.47 MPa; and 24.36, 27.50 MPa, respectively. The maximum stresses at the fracture end were as follows: 72.71, 70.51 MPa; 48.18, 22.80 MPa; 52.38, 27.14 MPa; and 34.05, 30.78 MPa, respectively. The fracture end displacement of the retrograde tension screw fixation model was the largest in both states, and the Magic screw had the smallest displacement variation in the standing state, but it was significantly higher than the two plate fixations in the sitting state. Magic screw can satisfy the biomechanical stability of posterior column fracture. Compared with traditional fixations, Magic screw has the advantages of more uniform stress distribution and less stress, and should be recommended.

Identifying safe corridors for anterior pelvic percutaneous instrumentation using computed tomography-based anatomical relationships

IntroductionPercutaneous anterior pelvic ring instrumentation is performed for retrograde screw fixation of ramus fractures, as well as for repair of pubic symphysis diastasis. The anatomic relationships of critical structures around the anterior pelvic ring, such as the spermatic cord and round ligament, have been described in only a few studies regarding the risk of iatrogenic injury during surgery. Our goal is to further describe these relationships, as well as provide radiographic information on safe corridors for percutaneous fixation. MethodsEighty (80) axial computed tomography scans of the abdomen, obtained for non traumatic diagnostic purposes and screened for prior abdominal trauma or procedures, were evaluated by 3 fellowship trained radiologists. Mid-symphyseal cuts were used to obtain several measurements relative to the spermatic cords (SC) or round ligaments (RL): inter-cord or inter-ligament distance, skin to cortex of symphysis distance (vertical), skin to cortex of symphysis distance (oblique), safe corridor distance (between SC/RL and femoral triangle), center safe angle (relative to bilateral ischia), maximal safe angle, and minimal safe angle. ResultsThere were 41 male and 39 female scans included in the final analysis. The average inter-cord distance was 50.2 mm, skin to cortex vertical distance of 43.0 mm, skin to cortex oblique distance of 83.5 mm, safe corridor distance 26.3 mm, center safe angle 19.3˚, maximal safe angle 32.3˚, and minimal safe angle 13.6˚. These were further broken down by range and gender in Table 1. Agreement between radiologists was high for these different measurements with the exception of the skin to cortex oblique distance in female patients and the maximal safe angle in female patients, due to absence of round ligament in a majority of the scans. The round ligament was only present at the mid-symphyseal level for our three reviewers in 37/39, 36/39, and 24/39 of female patient scans. ConclusionsWe have identified defined safe corridors for instrumentation of the anterior pelvic ring that can assist the surgeon in percutaneous application of fixation for fracture care.

Comparación de tres técnicas de tornillo endomedular mínimamente invasivo para fracturas de falange proximal. Estudio biomecánico

Background and objectivePhalangeal fractures are the most common hand fractures. In the last years, intramedullary compression screw (IMHCS) for instable transverse or short oblique proximal P1 fractures have been described. Although both anterograde (intraarticular or trans-articular) and retrograde IMHCS techniques have shown good results, no comparison between anterograde and retrograde screw in P1 fractures has been published. We sought to determine stability with retrograde IMHCS and anterograde IMHCS, both trans-articular and intra-articular technique, in a cadaveric transverse proximal P1 fracture model, at two different levels. Material and methodsWe performed a biomechanical study in 30 fresh-frozen human cadaveric P1 fracture model. Fracture was performed at 9-mm from the metacarpo-phalangeal (MCP) joint in 15 specimens, whereas it was done at 15 mm in the other 15. In turn, in each group, five fractures were stabilized with an anterograde intra-articular IMHCS, five with anterograde trans-articular IMHCS and other five with retrograde IMHCS. ResultsAnterograde IMHCS fixation in 9-mm P1 fractures (both trans- and intra-articular technique, 62.74 N and 70.86 N, respectively) was found to be more stable than retrograde IMHCS one (32.72 N) (p = 0.022). Otherwise, retrograde IMHCS fixation was found to be more stable in more distal P1 fractures (90.52 N retrograde vs. 57.64 N trans-articular vs. 42.92 N intra-articular; p = 0.20). ConclusionsAnterograde IMHCS fixation in proximal transverse P1 bone cut in a cadaveric model provides more stability than retrograde IMHCS, while retrograde screw provides more stability when the bone cut is located more distal.

Percutaneous screw fixation assisted by hollow pedicle finder for superior pubic ramus fractures

BackgroundPubic ramus fracture was an injury of anterior pelvic ring, the anterior pelvic ring plays an important role in maintaining the stability of the pelvis. The purpose of this study was to investigate the effect and indication of percutaneous retrograde pubic screw fixation assisted by hollow pedicle finder for pubic ramus fractures.MethodsThe clinical data of 68 patients with pubic ramus fracture treated with cannulated screw from March 2008 to March 2020 were retrospectively analyzed. According to the surgical methods, they were divided into traditional surgery group (32 cases in group A, with traditional retrograde pubic screw fixation) and modified surgery group (36 cases in group B, with percutaneous retrograde pubic screw fixation assisted by hollow open circuit device). Operation time, blood loss, incision length, screw length and complications were recorded and compared between the two groups. On the second day after surgery, the maximum fracture displacement over plain radiographs, entrance radiographs and exit radiographs of the pelvis was evaluated according to Matta criteria to evaluate the postoperative fracture reduction. Majeed score was used to evaluate the hip function at 12 months after surgery.ResultsThe operations were successfully completed in both groups. The operation time, blood loss and incision length in group B were significantly less than those in group A (P < 0.05). There was no significant difference in screw length between the two groups (t = 0.797, P = 0.431). All patients were followed up for 8–38 months (mean 21.8 months). There were no vascular and nerve injury, fracture of internal fixator, screw entry into joint cavity, fracture nonunion and other complications in both groups. The fracture healing time of the two groups was 23.1 ± 2.1 weeks in group A while 22.7 ± 2.1 weeks in group B, respectively, and there was no statistical difference in the fracture healing time between the two groups (P > 0.05). In group A, there were 3 cases of incision infection, 1 case of incision fat liquefaction and 2 cases of lower extremity deep venous thrombosis, and the complication rate was 18.8%. There was only 1 case of lower extremity deep vein thrombosis in group B, and the complication rate was 2.8%, which was significantly lower than that in group A. The fracture in one case after surgery was found to be displaced in group A and no fracture was found in group B. There was no significant difference between the two groups in Matta imaging evaluation on the next day after surgery and Majeed function evaluation at 12 months after surgery (P > 0.05).ConclusionPercutaneous retrograde pubic ramus screw fixation assisted by hollow pedicle finder is effective in the treatment of pelvic pubic ramus fracture. It has the advantages of less incision, shorter operation time, less blood loss and lower incidence of complications compared with traditional methods. However, correct surgical indications should be required when we apply this surgical method.

A New Technique for Anterior Pelvic Ring Fixation Using a Minimally Invasive Approach

Introduction: Percutaneous screw fixation have been introduced as a minimally invasive method in anterior pelvic ring fractures. The aim of the study is to present the outcomes of a new minimally invasive technique for fixation of anterior pelvic ring fractures medial to the pubic tubercle. Materials and Methods: Sixty-two patients were referred to our center during 5 years for the fixation of the anterior pelvic ring fracture under the new procedure. The fracture site was bridged using a 3-hole 3.5 mm reconstruction plate when 1 or 2 long retrograde screw was passed through the plate in the superior ramus. Results: A case of device failure was observed in the patient treated with the new method, which did not lead to loss of reduction and did not limit the patient’s activity. Apart from this, we did not have any abnormalities in the follow-up radiographs of the patients and no complications were reported. Conclusion: The results of this study showed the potential of our new method for fixation of various types of anterior pelvic ring injuries. Level of Evidence: Level IV.

Minimally invasive stabilization of fragility fractures of the pelvis with transsacral bar and retrograde transpubic screw

Stabilization of fragility fractures of the pelvis (FFP) using aminimally invasive technique. Insertion of atranssacral rod into the transsacral corridor of S1. Insertion of aretrograde transpubic screw through the superior branch of the pubic bone. Uni- or bilateral displaced fragility fractures of the sacrum or sacroiliac joint. Nondisplaced fractures of the sacrum or sacroiliac joint in case of nonsuccessful conservative treatment. Uni- or bilateral fractures of the superior branch of the pubic bone, which are present in combination with aposterior pelvic instability. Fragility fractures of the pelvis, which can be successfully treated conservatively. Absence of transsacral corridor in sacral body S1. Major displacement, nonreducible fractures of the superior branch of the pubic bone. Soft tissue infection at insertion site of implants. The transsacral bar is inserted under fluoroscopic control from ilium to ilium through the transsacral corridor of the sacral body S1. The retrograde transpubic screw is inserted from the pubic tubercle through the superior branch of the pubic bone past the acetabulum into the body of the ilium. An early mobilization with weight bearing of both lower extremities as tolerated by the patient is allowed. Conventional radiographs for control of the position of the implants and fractures are taken after mobilization RESULTS: In all, 64patients with FFP typeII, FFP typeIII or FFP typeIV were stabilized with atransacral bar osteosynthesis in the posterior pelvis. In 32patients (50%), additional sacroiliac screws were inserted. In 29patients (45.3%) the transsacral bar osteosynthesis was combined with atranspubic retrograde screw. Median length of hospital stay was 17.5days. In all, 20patients (31.3%) suffered general, 10patients (15.6%) suffered surgery-related complications, and 41patients (64.1%) were mobile in the room or on the ward at discharge. One-year mortality was 10.9%. The values of the SF‑8 Physical and Mental Component Scores, Parker Mobility Score and Numeric Rating Scale were moderate, yet comparable with the values of patients of the same age.

High results and lower cost in four-bone arthrodesis with retrograde screws.

Aim To describe the technique of the four-corner fusion with two retrograde crossed headless screws in cases of carpal collapse. Methods This technique is a consolidated procedure performed in cases of scaphoid non- union advanced collapse (SNAC) type II and III, scapholunate advanced collapse (SLAC) type II and III and in other cases of carpal collapse. Between 2017 and 2019 we treated six male patients (a mean age of 55.0 years) with radiocarpal osteoarthritis. Our technique involves the use of two retrograde crossed headless screws; the first screw was placed distally proximally from the uncinate to the lunate and the second screw from the pyramidal to the capitate, crossed at approximately 90 degrees. Clinical and radiographic two-year follow-up was performed. Before the treatment and during the follow-ups VAS, PRWE and DASH Quick score scales, measured wrist range of motion (WROM) were administered and evaluated. Results In all cases the X-ray consolidation of arthrodesis within five months was noticed; in 50% patients already under 3-month control. No observed signs of mobilization of screws and inflammatory or infectious processes were found. All patients were satisfied (reduction/disappearance of pain). All surgically treated patients resumed normal daily activities. These improvements were confirmed by the results of the evaluation scale and clinical examination. Conclusion This technique, in our opinion, represents a gold standard. Its low costs of the material used (especially comparing to other technique), a low prevalence of complications of materials and fusion in 100% of cases should be also considered.

Subtalar arthrodesis using a single compression screw: a comparison of results between anterograde and retrograde screwing.

The primary objective of this study was to compare the radiological and clinical results of anterograde and retrograde screwing in subtalar arthrodesis using a single compression screw. The secondary objective was to evaluate the subjective results and consolidation of this procedure. The hypotheses were that isolated screw fixation was sufficient to achieve good consolidation and that there was no difference between the two techniques with a similar rate of bone fusion. This is a monocentric, retrospective, radio-clinical study based on 99 patients (101 feet), 58 males and 41 females, with an average age of 64years. The main aetiology was post-traumatic osteoarthritis, which represented 51% of cases. Two groups were formed: group A (52 feet) consisting of fixed arthrodesis with ascending (retrograde) screwing and group D (49 feet) consisting of fixed arthrodesis with descending (anterograde) screwing. The two groups were statistically comparable in terms of demographic data as well as aetiologies and comorbidities. Arthrodeses which were not fused at 6months were reassessed at one year and in the event of any radio-clinical doubt regarding consolidation, an additional CT scan was prescribed. Average post-operative follow-up was 11 ± 5years (2-27years). Ninety-two arthrodeses (93%) were fused at one year and 9 were considered to be in non-union, 5 (9.8%) in group A, and 4 (8.3%) in group D. We recorded 30 complications, 22 of which were due to a conflict with the screw head, 18 (34.5%) in group A and 4 (8.3%) in group D (p = 0.03). Conflict between the screw head and the heel led to the removal of the screw after consolidation of the arthrodesis. The clinical results were evaluated using Odom's criteria. Nine per cent of patients described their results as excellent, 29% as good, 51% as satisfactory and 11% found the result to be poor. The fusion rate for isolated compression screw arthrodesis is good, and there is no difference between anterograde and retrograde screws. However, the discomfort caused by the screw head being insufficiently embedded in the retrograde group led to a non-negligible number of additional surgeries to remove the screw.

Anatomical evaluation of the transpubic screw corridor based on a 3D statistical model of the pelvic ring

Retrograde transpubic screw fixation is a common procedure for the treatment of anterior pelvic ring fractures. With its sparing surgical approach and significant pain relief after screw fixations allowing early mobilisation, it has gained importance especially in the treatment of insufficiency fractures in elderly patients. However, positioning of transpubic screw osteosynthesis is not always possible due to narrowness and curvature of the screw corridor. The aim of the present study was to evaluate availability and length of the screw corridor using a 3D statistical model of the pelvic ring consisting out of 150 uninjured pelves. Virtual bore probes with a diameter of 7.5 mm were analysed as to accessibility, length and grey value distribution in Hounsfield Unit (HU). A transpubic corridor with a diameter of ≥ 7.5 mm was available in 185 of 300 investigated superior pubic rami with mean screw length of 131.7 mm. Accessibility of the screw corridor was higher in males than in females. However, screw length showed no systematic differences between the sexes or ethnicities. Analysis of the grey value distribution demonstrated the strongest bone to be located at the lateral ilium and the supraacetabular region.

Digital study of the ideal position of lag screw internal fixation in the anterior column of the acetabulum

To find the ideal position of lag screw internal fixation in the anterior column of acetabulum by digital technology, and measure its related parameters, so as to improve the accuracy of lag screw implantation. The CT scan data of 266 semi-pelvic raw in 133 cases (78 males and 55 females, aged 18-65 years old with an average age of 42 years) were collected between January 2019 and January 2020 to compose three-dimensional models. According to the relationship between the peripheral bone cortex of the anatomical channel and the lag screw, a new standard for the ideal position of lag screw fixation in the anterior column of acetabulum was proposed to simulate the implantation of the screw. After the screw was in the ideal position, the following indicators were measured: the maximum allowable diameter of the virtual screw (the diameter of the cylinder up to the new standard, R), the length (the distance between the center of the nail point on both sides, L); the position of the retrograde nail point (the interval between the nail insertion points and the midpoint of the pubic symphysis and the pubic tubercle, respectively, D1 and D2) and the position of the antegrade nail insertion point (the distance between the nail insertion point and the anterior superior iliac spine, the major ischial notch, and the vertical distance between the nail insertion point and the apex of the posterior upper edge of the acetabulum, respectively, D3, D4, D5); and the direction of the virtual screw at the ideal position (the angle between the screw and the horizontal plane, sagittal plane, and coronal plane, respectively, ∠β, ∠γ, ∠δ) were calculated. The maximum allowable diameter of virtual screws was 5.70-14.10 mm for males, with an average of 9.25 mm; for females, it was 4.40-10.40 mm with an average of 7.29 mm. The antegrade insertion point of the anteroposterior acetabular lag screw was located at 2.0-2.5 cm above the apex of the acetabulum, which was almost the same distance from the anterior superior iliac spine and the ischial notch, about 5 cm; the insertion point of the retrograde implant was located at the pubic bone 2.5-3.0 cm below the nodule. When the acetabular anterior column screw was in the ideal position, there was no significant difference in the comparison of ∠β and ∠γ between the male and the female ( P>0.05), and the differences in the other indicators were significant ( P<0.05). Except for D4 and ∠β showing no significant difference between the left and right sides ( P>0.05), the differences in the other indicators were significant ( P<0.05). In the bony channel of the anterior column of the acetabulum, all males can accommodate screws with a diameter of <5.70 mm, and females can accommodate screws with a diameter of <4.40 mm. The anterograde or retrograde screw insertion points are different for male and female. The use of digital technology to individually measure the appropriate screw parameters can improve the accuracy and stability of the lag screw internal fixation for acetabular anterior column fractures.

Factors Associated With Failure of Superior Pubic Ramus Screws.

Examine factors associated with fixation failure in patients treated with superior intramedullary ramus screws. Retrospective. Single, Level 1 trauma center. Unstable pelvic ring fractures amenable fixation that included superior intramedullary ramus screws. Percutaneously inserted intramedullary superior ramus screw fixation of superior pubic ramus (SPR) fractures. Loss of reduction (LOR) of the SPR fracture defined as >2 mm displacement on pelvic radiographs at any time point in follow-up. Two hundred eighty-five fractures in 211 patients (age 44, 95% confidence interval 40.8%-46.4%, 59.3% women, 55.1% retrograde screws) were included in the analysis. 14 (4.9%) of fractures had LOR. Patients were significantly more likely to have LOR as age increased (P = 0.01), body mass index (BMI) increased (P = 0.01), and if they were women (P < 0.01). There was a significantly decreased LOR (P < 0.01) as fractures moved further from the pubis symphysis. Retrograde screws were significantly (P < 0.01) more likely to have LOR. In SPR fractures treated with retrograde screws, failure was significantly associated with increasing BMI (P = 0.02), the presence of an inferior ramus fracture (P = 0.02), and trended toward significance with increasing age (P = 0.06), and decreased distance from the symphysis (P = 0.07). Superior ramus screws are associated with a low failure rate (4.9%), which is lower than previously reported. Retrograde screw insertion, distance from the symphysis, increasing age, increasing BMI, decreased distance from the symphysis, and ipsilateral inferior ramus fractures were predictors of failure. In these patients, alternative modalities should be considered, although low rates of failure can still be expected. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Percutaneous fixation of acute scaphoid waist fractures: Long-term patient-reported functional outcomes and satisfaction at a mean of 11 years following surgery

The aim of this study was to report the long-term functional outcomes and complication rates following early percutaneous fixation of acute fractures of the scaphoid. A trauma database was searched to identify all skeletally-mature patients with an undisplaced or minimally-displaced scaphoid waist fracture managed with early percutaneous retrograde screw fixation over a thirteen-year period from 1997−2010. Medical records were retrospectively reviewed, and complications documented. Long-term follow-up was by a questionnaire-based review. The Patient-Rated Wrist Evaluation (PRWE) was the primary outcome measure. Secondary outcomes included the Quick version of the Disability of the Arm, Shoulder and Hand score (QuickDASH), the EuroQol 5-dimensions score (EQ-5D-5L), and complications. During the study period 114 patients underwent this procedure. The mean age was 28 years (range 17–62) and 97 patients (85%) were male. The median time from injury to surgery was nine days (range 1–27). Twelve patients (11%) reported a complication, all of whom required repeat surgical intervention (six revision ORIF for non-union, five elective removal of hardware, one early revision fixation due to screw impingement). Long-term outcome data was available for 77 patients (68%) at mean follow-up of 11.4 years (range 6.4–19.8). The median PRWE was 0 (IQR 0–7.5), median QuickDASH 0 (IQR 0–4.5) and median EQ-5D-5L 1.0 (IQR 0.837–1.0). There were 97% (n = 74) patients satisfied with their outcome. Early percutaneous fixation of acute non-displaced or minimally displaced scaphoid fractures results in good long-term patient reported outcomes and health-related quality of life. Although comparable with previous studies, the overall surgical reintervention rate is notable and can result in inferior outcomes. Level of evidenceTherapeutic level III (Retrospective Cohort Study).