The infraacetabular screw - anatomy, radiology, biomechanics and clinics.

Acetabular fracture surgery follows the primary aim of anatomic reduction and rigid stable fixation of the fracture. Infraacetabular screws (IAS) allow for an increased stability of the acetabular fixation by closing the periacetabular fixation frame without requiring an additional posterior approach. The osseous screw corridor for infraacetabular screws use the transition zone between the acetabular ring and the obturator ring. The infraacetabular screw corridor (IAC) shows a double-cone shape with an isthmus located near the acetabular fovea. The iliopectineal eminence (IE) is mainly used as a clinical landmark for the intraoperative assessment of the entry point of IAS. The inlet view, the combined obturator oblique outlet view and a 1/3 iliac oblique outlet view may be used for the intraoperative radiological assessment for both the entry point and the screw trajectory of IAS. Several biomechanical studies have shown that IAS increase the stiffness of the internal fixation. Scientific proof for an improved clinical outcome is still missing.

Acetabular posterior column screws via an anterior approach.

Screw fixation of acetabular column fractures is a well-established alternative option to plate fixation providing comparable biomechanical strength and requiring less surgical exposure. For displaced acetabular fractures involving both columns open reduction and plate fixation of one column in combination with a column-crossing screw fixation of the opposite column via a single approach is a viable treatment option. Preoperative planning of posterior column screws (PCS) via an anterior approach is mandatory to assess the eligibility of the fracture for this technique and to plan the entry point and the screw trajectory. The intraoperative application requires fluoroscopic guidance using several views. A single view showing an extraarticular screw position is adequate to rule out hip joint penetration. The fluoroscopic assessment of cortical perforation of the posterior column requires several oblique views such as lateral oblique views, obturator oblique views and axial views of the posterior column or alternatively intraoperative CT scans. The application of PCS via an anterior approach is a technically demanding procedure, that allows for a relevant reduction of approach-related morbidity, surgical time and blood loss by using a single approach.

The Pararectus approach: a preferred surgical approach for fixation of acetabular fractures predominantly involving the anterior column - a narrative review.

Beginning in France in the 1960s, the management of acetabular fractures has increasingly evolved toward surgical treatment strategies. The basic principles established by the pioneers of acetabular surgery, Letournel and Judet - anatomical reconstruction of the joint and stable osteosynthesis - remain unchanged. Modern advancements in surgical techniques aim to reduce access-related trauma and minimize complications. The notable rise in acetabular fractures among the elderly, which predominantly affect the anterior aspects of the acetabulum, has driven the development of less invasive, soft tissue-sparing anterior approaches. This evolution began with the ilio-inguinal approach in the 1960s, progressed to the modified Stoppa approach in the 2000s and, most recently, the Pararectus approach in the 2010s. Each of these approaches upholds the fundamental principles of effective acetabular fracture care, while offering distinct advantages and disadvantages. In this review, we examine the merits and limitations of the Pararectus approach, specifically focusing on its utility in the surgical treatment of anterior column posterior hemitransverse acetabular fractures. Ultimately, the success of the individual patient's outcome is less dependent on the chosen approach and more on the surgeon's experience and expertise. Ideally, surgeons should be proficient in all these approaches to tailor the surgical strategy to the individual patient's requirements, thereby ensuring optimal outcomes.

Acetabular fractures in geriatric patients: epidemiology, pathomechanism, classification and treatment options.

The incidence of geriatric acetabular fractures has shown a sharp increase in the last decades. The majority of patients are male, which is different to other osteoporotic fractures. The typical pathomechanism generally differs from acetabular fractures in young patients regarding both the direction and the amount of force transmission to the acetabulum via the femoral head. Geriatric fractures very frequently involve anterior structures of the acetabulum, while the posterior wall is less frequently involved. The anterior column and posterior hemitransverse (ACPHT) fracture is the most common fracture type. Superomedial dome impactions (gull sign) are a frequent feature in geriatric acetabular fractures as well. Treatment options include nonoperative treatment, internal fixation and arthoplasty. Nonoperative treatment includes rapid mobilisation and full weighbearing under analgesia and is advisable in non- or minimally displaced fractures without subluxation of the hip joint and without positive gull sign. Open reduction and internal fixation of geriatric acetabular fractures leads to good or excellent results, if anatomic reduction is achieved intraoperatively and loss of reduction does not occur postoperatively. Primary arthroplasty of geriatric acetabular fractures is a treatment option, which does not require anatomic reduction, allows for immediate postoperative full weightbearing and obviates several complications, which are associated with internal fixation. The major issue is the fixation of the acetabular cup in the fractured bone. Primary cups, reinforcement rings or a combination of arthroplasty and internal fixation may be applied depending on the acetabular fracture type.

Influence of positive end-expiratory pressure on arterial blood pressure in mechanically ventilated trauma patients in the field: a retrospective cohort study.

Ventilation with positive end-expiratory pressure (PEEP) may result in decreased venous return to the heart and therefore decrease cardiac output. We evaluated the influence of PEEP ventilation on arterial blood pressure in the field in 296 posttraumatic intubated patients being treated by a helicopter emergency medical service in a retrospective cohort study. Initial systolic blood pressure on the scene, upon hospital admission and their mean difference were compared between patients being ventilated with no/low PEEP (0-0.3 kPa) and moderate PEEP (0.3-1 kPa). In a subgroup analysis of initially hemodynamic unstable patients (systolic blood pressure < 80 mmHg), systolic blood pressure was compared between patients being ventilated with no/low or moderate PEEP Further, the mean difference between initial systolic blood pressure and upon hospital admission was correlated with the chosen PEEP. Systolic arterial blood pressure of patients being ventilated with no/low PEEP improved from 105 ± 36 mmHg to 112 ± 38 mmHg, and that of patients being ventilated with moderate PEEP improved from 105 ± 38 mmHg to 119 ± 27 mmHg. In initially unstable patients being ventilated with no/low PEEP systolic blood pressure improved from initially 55 ± 36 mmHg to 78 ± 30 mmHg upon hospital admission, and in those being ventilated with moderate PEEP, the systolic blood pressure improved from 43 ± 38 mmHg to 91 ± 27 mmHg. There was no significant correlation between the chosen PEEP and the mean difference of systolic blood pressure (Pearson's correlation, r = 0.07, P = 0.17). Ventilation with moderate PEEP has no adverse effect on arterial systolic blood pressure in this cohort of trauma patients requiring mechanical ventilation. Initially unstable patients being ventilated with moderate PEEP tend to be hemodynamically more stable.

Migration characteristics of the Corail hydroxyapatite-coated femoral stem-a retrospective clinical evaluation and migration measurement with EBRA.

PURPOSE: Uncemented stem migration analysis by EBRA-FCA (Einzel-Bild-Roentgen Analyse, Femoral Component Analysis) has been seen to be a good predictive indicator for early implant failure. In this study, we investigated the migration behavior of a cementless press-fit stem after two years follow-up. Stem type and postoperative gap between collar and femur were evaluated as a risk factor. METHODS: Applying a retrospective study design, we reviewed all consecutive patients who between 2013 and 2017 received a cementless press-fit Corail stem (DePuy Orthopaedics Inc., Warsaw, IN, USA) at our Department. We reviewed medical histories and performed radiological measurements using EBRA-FCA software. RESULTS: A total of 109 stems in 105 patients (female: 60; male: 45) fulfilled our inclusion criteria. Mean age at surgery was 67.8 (range, 21.6-90.5) years. EBRA migration analysis showed a mean subsidence of 1.8 mm (range, 0.0-12.1) at final follow-up. At 18 months mean subsidence of collared stems was significantly lower than in the collarless group [1.3 mm (range, 0.0-7.6) vs. 3.2 mm (range, 0.5-10.7), p = 0.0104]. Collared stems resting on the femoral cut presented a tendency to less subsidence than did collared stems showing a postoperative gap between collar and femur (1.3 vs. 2.0 mm) without finding statistical significance (p > 0.05). CONCLUSIONS: Low subsidence and the migration pattern of the cementless press-fit stem may predict a good long-term result. Collared stems investigated in our study provide good stability and are able to prevent significant subsidence. Trial registration number and date of registration: Number: 20181024-1875; Date: 2018-10-24.

The acetabular roof reinforcement plate for the treatment of displaced acetabular fractures in the elderly: results in 59 patients.

INTRODUCTION: Open reduction and internal fixation is considered the gold standard of treatment for displaced acetabular fractures in younger patients. For elderly patients with osteoporotic bone quality, however, primary total hip arthroplasty (THA) with the advantage of immediate postoperative mobilization might be an option. The purpose of this study was to evaluate the clinical and radiological outcomes of surgical treatment of displaced osteoporotic acetabular fractures using the acetabular roof reinforcement plate (ARRP) combined with THA. MATERIALS AND METHODS: Between 2009 and 2019, 84 patients were operated using the ARRP combined with THA. Inclusion criteria were displaced osteoporotic fractures of the acetabulum with or without previous hemi- or total hip arthroplasty, age above 65 years, and pre-injury ability to walk at least with use of a walking frame. Of the 84 patients, 59 could be followed up after 6 months clinically and radiographically. Forty-nine (83%) were primary fractures and 10 (17%) periprosthetic acetabular fractures. RESULTS: The mean age was 80.5 years (range 65-98 years). The average time from injury to surgery was 8.5 days (range 1-28). Mean time of surgery was 167 min (range 100-303 min). Immediate postoperative full weight bearing (FWB) was allowed for 51 patients (86%). At the 6-month follow-up, all 59 patients except one showed bony healing and incorporation of the ARRP. One case developed a non-union of the anterior column. No disruption, breakage or loosening of the ARRP was seen. Additional CT scans performed in 18 patients confirmed bony healing. Twenty-six patients (44%) had regained their pre-injury level of mobility. Complications requiring revision surgery occurred in 8 patients. Five of them were suffering from a prosthetic head dislocation, one from infection, one from hematoma and one from a heterotopic ossification. CONCLUSIONS: The ARRP has proven to provide sufficient primary stability to allow for immediate FWB in most cases and represents a valuable option for the surgical management of displaced acetabular fractures in this challenging patient group.

Subsidence of a metaphyseal-anchored press-fit stem after 4-year follow-up: an EBRA-FCA analysis.

PURPOSE: Uncemented stem migration analysis by EBRA-FCA (Einzel-Bild-Roentgen Analyse, Femoral Component Analyse) has been seen to be a good predictive indicator for early implant failure. In this study, we investigated the migration behavior of a cementless metaphyseal-anchored press-fit stem after 4-year follow-up. METHODS: Applying a retrospective study design, we reviewed all consecutive patients who between 2012 and 2017 received a cementless Accolade II press-fit stem at our Department. We reviewed medical histories and performed radiological measurements using EBRA-FCA software. EBRA-FCA measurements and statistical investigations were performed by two independent investigators. RESULTS: A total of 102 stems in 91 patients (female 60; male 31) fulfilled our inclusion criteria. Mean age at surgery was 66.2 (range 24.3-92.6) years. EBRA migration analysis showed a mean subsidence of 1.4 mm (range 0.0-12.0) at final follow-up. The angle between stem and femur axis was 0.5° (range 0.0°-2.8°) after 48 months. No correlations between gender or Dorr types and subsidence were found (p > 0.05). A body mass index > 30 kg/m2 showed a significant increase in stem subsidence within the first 6 (p = 0.0258) and 12 months (p = 0.0466) postoperative. CONCLUSIONS: Migration pattern of the metaphyseal-anchored stem and a low subsidence rate at final follow-up may predict a good long-term clinical result. TRIAL REGISTRATION: Number: 20181024-1875.

Bilateral medial medullary syndrome following anterior screw fixation of type 2 odontoid fracture, a case report of two patients.

INTRODUCTION: Medial medullary syndrome (MMS) has not been reported after anterior screw fixation of an odontoid type 2 fracture. CASE PRESENTATION: We report on two cases who suffered from an unstable type 2 odontoid fracture following a skiing and a domestic fall accident. Prior to anterior screw fixation surgery both patients presented without neurologic deficits but postoperatively developed a bilateral MMS, including an incomplete tetraparesis, impaired sensation of position and movement as well as tactile discrimination and paralysis of the tongue muscle with deviation to the paralyzed side. MRI showed a typical heart-shaped ischaemic lesion in the medial medulla bilaterally. The search for aetiologic factors was uneventful in both patients except for severe atherosclerosis. DISCUSSION: Due to the close proximity of the ischaemic area to the surgical site, we here propose the perioperative mechanical manipulation of the upper cervical spine during surgery of patients with atherosclerosis as a new aetiology for MMS.

Common Pitfalls in the Management of Bone Metastasis of the Extremities - a Current Concept and Systematic Review of the Literature.

BACKGROUND/AIM: The surgical treatment of patients with bone metastasis of the extremities poses a set of unique challenges. We aimed to highlight common hazards when treating pathological fractures as well as hazards surrounding assumptions on metastatic status and life expectancy. MATERIALS AND METHODS: This systematic literature review includes studies published from January 1, 1985 to May 7, 2021. Published articles were surveyed using PubMed. Of 99 studies, 32 original articles were found to meet the inclusion criteria. The PRISMA guidelines were used to select articles. RESULTS: Current literature reports a variety of common pitfalls. In order to avoid pitfalls, it is essential to secure the diagnosis. Furthermore, life expectancy must be given consideration when planning surgical therapy. In addition, a well-functioning multidisciplinary team is needed to coordinate further options such as radiation or embolization. CONCLUSION: Despite the fact that the surgical principles for treating bone metastases of the extremities are often to the point, incorporating all the nuances of treatment is a meticulous procedure.

Single column plate plus other column lag screw fixation vs. both column plate fixation for anterior column with posterior hemitransverse acetabular fractures - a biomechanical analysis using different loading protocols.

OBJECTIVES: Open reduction and internal fixation of both columns is considered the treatment of choice for displaced anterior column with posterior hemitransverse (ACPHT) fractures in non-geriatric patients. Plate fixation of one column combined with lag screw fixation of the other column allows to decrease operative time and approach-related morbidity compared to conventional both column plating. The aim of this biomechanical study was to evaluate whether single column plate plus other column lag screw fixation confers similar stability to both column plate fixation. Physiological loads were simulated using both the single-leg stance (SLS) as well as the sit-to-stand (STS) loading protocols. METHODS: A clinically relevant ACPHT fracture model was created using fourth-generation composite hemipelves. Fractures were stabilized with three different fixation constructs: (1) anterior column plate plus posterior column screw fixation (AP+PCS), posterior column plate plus anterior column screw fixation (PP+ACS) and anterior column plate plus posterior column plate fixation (AP+PP). Specimens were loaded from 50 to 750 N with a ramp of 100 N/s. Fracture gap motion (FGM) and relative interfragmentary rotation (RIFR) between the three main fracture fragments were assessed under loads of 750 N using an optical 3D measurement system. RESULTS: STS loading generally resulted in higher mean FGM and RIFR than STS loading in the AP+PCS and AP+PP groups, while no significant differences were found in the PP+ACS group. Compared to conventional both column plate fixation (AP+PP), PP+ACS displayed significantly higher FGM and RIFR between the iliac wing and the posterior column during SLS loading. No significant differences in FGM and RIFR were identified between the AP+PCS and the AP+PP group. CONCLUSION: Overall, single column plate plus other column lag screw fixation conferred similar stability to conventional both column plate fixation. From a clinical point of view, AP+PCS appears to be the most attractive alternative to conventional AP+PP for internal fixation of ACPHT fractures.

An alphanumeric classification of osteoporotic pelvic ring injuries.

INTRODUCTION: Classification and management of osteoporotic pelvic ring injuries (OPRI) continue to pose a considerable challenge to orthopaedic traumatologists. The currently used fragility fractures of the pelvis (FFP) classification of OPRI has recently been shown to have significant weaknesses. The aim of this study therefore was to propose a new, simple, yet comprehensive alphanumeric classification (ANC) of OPRI and to assess its intra- and interobserver reliability. Furthermore, its potential advantages over the FFP classification are discussed. MATERIALS AND METHODS: One hundred consecutive CT scans from patients with OPRI were evaluated by three orthopaedic traumatologists with varying levels of experience and one musculoskeletal radiologist. Intra- and interobserver reliability of the proposed classification system was assessed using weighted kappa (κ) statistics and percentage agreement. In addition, the Fleiss' kappa statistic was computed to assess interobserver agreement among all four raters. RESULTS: Overall intraobserver reliability of the proposed ANC was substantial [κ ranging from 0.71 to 0.80; percentage agreement: 70% (range, 67-76%)]. Overall interobserver reliability between pairs of raters was substantial as well [κ ranging from 0.61 to 0.68; percentage agreement: 58% (range, 53-61%)]. For ANC types, groups and subgroups, intra- and interobserver reliability were substantial to almost perfect. Interobserver agreement among all four raters was moderate to substantial, with Fleiss' kappa values of 0.48, 0.69, 0.71 and 0.52 for ANC overall, types, groups and subgroups, respectively. CONCLUSION: The proposed ANC of OPRI demonstrated overall reliability comparable to that of the FFP classification. The ANC, however, is simple, more comprehensive, and consistently relates to injury severity.

Biomechanical comparison of fixation techniques for transverse acetabular fractures - Single-leg stance vs. sit-to-stand loading.

OBJECTIVES: To biomechanically compare five different fixation techniques for transverse acetabular fractures using both the single-leg stance (SLS) and the sit-to-stand (STS) loading protocols and to directly compare fracture gap motion (FGM) and relative interfragmentary rotation (RIFR). METHODS: Transtectal transverse acetabular fractures were created on fourth-generation composite hemipelves in a reproducible manner. Five different fixation techniques were biomechanically assessed using both an SLS and STS loading protocol: anterior plate (AP) only, posterior plate (PP) only, anterior plate plus posterior column screw (AP+PCS), posterior plate plus anterior column screw (PP+ACS) and anterior plus posterior plate (AP+PP). After preconditioning, the specimens were loaded from 50 to 750 N with a ramp of 100 N/s. FGM and RIFR under loads of 750 N were measured using an optical 3D measurement system. RESULTS: In the three groups of fixation techniques addressing both columns, STS loading resulted in higher mean FGM and in RIFR than SLS loading. No construct failure was observed. In the single plate groups (AP only and PP only), STS loading resulted in failure of all specimens before reaching loads of 750 N, while no failure occurred after SLS loading. No significant differences in FGM and RIFR were found between the double plate (AP+PP) and the single plate plus column screw (AP+PCS and PP+ACS) techniques. CONCLUSION: SLS loading appeared to overestimate the strength of acetabular fracture fixation constructs and STS loading may be more appropriate to provide clinically relevant biomechanical data. Internal fixation of a single column might not provide adequate stability for transverse fractures, while strength of single plate plus column screw fixation and double plate fixation was comparable.

Cervical Disc and Ligamentous Injury in Hyperextension Trauma: MRI and Intraoperative Correlation.

BACKGROUND AND PURPOSE: To identify and evaluate diagnostic magnetic resonance imaging (MRI) features in patients with suspicion of discoligamentous cervical injury after hyperextension trauma of the cervical spine. METHODS: MR images with a standard protocol (1.5 T, including sagittal T2-weighted images and short tau inversion recovery [STIR]) in 21 patients without any sign of fracture or instability on multidetector computed tomography of the cervical spine were assessed. Among other structures we evaluated the following: prevertebral hematoma, anterior longitudinal ligament (ALL), intervertebral disc, and spinal cord. Presence and the anatomic level of injury were identified and recorded. Results were then compared with intraoperative findings as a reference standard. Simple descriptive statistical analysis, agreement coefficients (given by calculating the percent agreement), and the determination of Gwet's AC1 coefficient were used to analyze our results. RESULTS: The overall percent agreement between STIR and intraoperative findings was 90.9% (AC1 = .881) and for T2 69.7% (AC1 = .498). For the ALL, the overall agreement was 87.9% (AC1 = .808) and for the intervertebral disc 78.8% (AC1 = .673), in which STIR always showed a higher agreement. Prevertebral hematoma was found in 20 of 21 patients with the maximum thickness at the same anatomic level as the intraoperatively proven lesion in 12 of 18 patients (67%). Edema and/or hemorrhage of the spinal cord was shown in 16 of 21 being at the same anatomic level as the intraoperatively confirmed pathology in 16 of 16 patients (100%). CONCLUSIONS: MRI is a reliable tool for the evaluation of discoligamentous injuries in the cervical spine, with ancillary features proven as helpful information.

Brake reaction time before and after surgery for patients with sequestrectomy versus conventional microdiscectomy.

The aim of this study was to compare the effects of sequestrectomy versus conventional microdiscectomy on breaking response time (BRT) for lumbar disc herniation (LDH). BRT is the key factor for return to drive recommendations after surgery. A prospective clinical study was conducted. Patients aged 25-65 years who underwent surgery for lumbar disc herniation and held a valid motorcar driving license were recruited in a single institution. The patients were assessed before surgery, immediately after the surgery and at the follow up examination 30 days post-surgery. BRT was measured using a driving simulator, a visual analogue scale (VAS) was used for pain assessment. BRT values were compared with BRT values of a healthy control group. In patients treated with microdiscectomy BRT reduced from 749 (±223) msec before surgery to 649 (±223) msec immediately after the surgery. In the sequestrectomy group BRT reduced from 852 (±561) msec before surgery to 693 (±173) msec immediately after the surgery. BRT at follow up was 610 (±145) msec for patients treated with microdiscectomy and 630 (±98) msec for patients operated with sequestrectomy. BRT for healthy controls was 487 (±116) msec. Pain improved significantly for both patient samples. Sequestrectomy and microdiscectomy were associated with similar effects on pain and BRT after surgery. There was no statistically significant difference between BRT of both patient samples at 30 days follow up examination. Both surgical techniques showed a positive effect on BRT. No statistically significant difference between sequestrectomy and microdiscectomy on BRT could be found.

Fluoroscopically guided acetabular posterior column screw fixation via an anterior approach.

OBJECTIVE: Safe posterior column screw fixation via an anterior approach under two-dimensional fluoroscopic control. INDICATIONS: Anterior column with posterior hemitransverse fractures (ACPHF); transverse fractures; two-column fractures and T­type fractures without relevant residual displacement of the posterior column after reduction of the anterior column and the quadrilateral plate. CONTRAINDICATION: Acetabular fractures requiring direct open reduction via a posterior approach; very narrow osseous corridor in preoperative planning; insufficient intraoperative fluoroscopic visualization of the anatomical landmarks. SURGICAL TECHNIQUE: Preoperative planning of the starting point and screw trajectory using a standard pelvic CT scan and a multiplanar reconstruction tool. Intraoperative fluoroscopically controlled identification of the starting point using the anterior-posterior (ap) view. Advancing the guidewire under fluoroscopic control using the lateral-oblique view. Lag screw fixation of the posterior column with cannulated screws. POSTOPERATIVE MANAGEMENT: Partial weight bearing as advised by the surgeon. Postoperative CT scan for the assessment of screw position and quality of reduction of the posterior column. Generally no implant removal. RESULTS: In a series of 100 pelvic CT scans, the mean posterior angle of the ideal posterior column screw trajectory was 28.0° (range 11.1-46.2°) to the coronal plane and the mean medial angle was 21.6° (range 8.0-35.0°) to the sagittal plane. The maximum screw length was 106.3 mm (range 82.1-135.0 mm). Twelve patients were included in this study: 10 ACPHF and 2 transverse fractures. The residual maximum displacement of the posterior column fracture component in the postoperative CT scan was 1.4 mm (0-4 mm). There was one intraarticular screw penetration and one perforation of the cortical bone in the transition zone between the posterior column and the sciatic tuber without neurological impairment.

Preoperative planning and safe intraoperative placement of iliosacral screws under fluoroscopic control.

OBJECTIVE: Preoperative planning of the starting point and safe trajectory for iliosacral screw (SI screw) fixation using CT scans for safe and accurate fluoroscopically controlled percutaneous SI screw placement. INDICATIONS: Transalar and transforaminal sacral fractures. SI joint disruptions and fracture-dislocations. Non- or minimally displaced spinopelvic dissociation injuries. CONTRAINDICATIONS: Transiliac instabilities. Sacral fractures with neurological impairment requiring decompression. Relevant residual displacement after closed reduction attempts. Insufficient fluoroscopic visualization of the anatomical landmarks of the upper sacrum. SURGICAL TECHNIQUE: Preoperative planning of the starting point and the safe screw trajectory using CT scans and two-dimensional multiplanar reformation tools. Fluoroscopically guided identification of the starting point using the lateral view according to preoperative planning. Advancing the guidewire under fluoroscopic control using inlet and outlet views according to the planned trajectory. Predrilling and placement of 6.5 mm cannulated screws. POSTOPERATIVE MANAGEMENT: Weightbearing as tolerated using crutches. Immediate CT scan in case of postoperative neurological impairment. Generally no screw removal. RESULTS: Fifty-nine screws were placed in 34 patients using the described technique. There were 2 cases of screw malpositioning (anatomical landmarks inadequately identified and fluoroscopically controlled SI screw fixation should thus not have been performed at all; in a case with sacral dysmorphism, preoperative planning suggested a posterior and/or caudal S1 starting point, respectively, but intraoperatively, selection of a different starting point and screw trajectory resulted in screw malpositioning with iatrogenic L5 nerve palsy).

Risk factors for nonunion after intramedullary nailing of subtrochanteric femoral fractures.

INTRODUCTION: Nonunion is a common complication after intramedullary nailing of subtrochanteric femoral fractures. A more detailed knowledge, particularly of avoidable risk factors for subtrochanteric fracture nonunion, is thus desired to develop strategies for reducing nonunion rates. The aim of the present study therefore was to analyse a wide range of parameters as potential risk factors for nonunion after intramedullary nailing of subtrochanteric fractures. MATERIALS AND METHODS: Seventy-four patients who sustained a subtrochanteric fracture and were treated by femoral intramedullary nailing at a single level 1 trauma centre within a 6-year period were included in this study. A total of 15 patient-related, fracture-related, surgery-related, mechanical and biological parameters were analysed as potential risk factors for nonunion. Furthermore, the accuracy of each of these parameters to predict nonunion was calculated. RESULTS: Nonunion occurred in 17 of 74 patients (23.0%). Of the 15 potential risk factors analysed, only 3 were found to have a significant effect on the nonunion rate (p < 0.05): postoperative varus malalignment, postoperative lack of medial cortical support and autodynamisation of the nail within the first 12 weeks post-surgery. Accuracy of each of these 3 parameters to predict nonunion was > 0.70. Furthermore, the nonunion rate significantly increased with the number of risk factors (no risk factor: 2.9%, one risk factor: 23.8%, two risk factors: 52.9%, and three risk factors: 100% [Chi-square test, p = 0.001)]. CONCLUSIONS: Our study indicates that intraoperative correction of varus malalignment and restoration of the medial cortical support are the most critical factors to prevent nonunion after intramedullary nailing of subtrochanteric femoral fractures. In addition, autodynamisation of the nail within the first 3 months post-surgery is a strong predictor for failure and should result in revision surgery.