Computer-assisted navigation for intramedullary nail fixation of intertrochanteric femur fractures: A randomized,controlled trial

IntroductionLag screw cutout is one of the most commonly reported complications following intramedullary nail fixation of intertrochanteric femur fractures. However, its occurrence can be minimized by a well-positioned implant, with a short Tip-to-Apex Distance (TAD). Computer-assisted navigation systems provide surgeons with the ability to track screw placement in real-time. This could allow for improved lag screw placement and potentially reduce radiation exposure to the patient and surgeon.MethodsBetween Oct 2014 and Jan 2016, patients with intertrochanteric femur fractures being treated with intramedullary nail fixation by one of three fellowship-trained orthopaedic traumatologists were enrolled. Inclusion criteria were low-energy mechanism of injury and fracture class 31-A1/A2. Open fractures and patients with multiple injuries to the lower extremity were excluded. Patients were randomly assigned to computer-assisted navigation or a conventional fluoroscopic technique for lag screw placement. The primary outcomes were TAD, measured by postoperative anteroposterior and lateral x-rays by an independent reviewer, and radiation exposure measured in seconds of fluoroscopy time. Surgical time was also recorded.Results50 patients were randomized, 26 to the computer-assisted navigation group and 24 to the control group. The mean manually-measured TAD in the computer-assisted navigation group was 14.1 mm ± 3.2 and in the control group was 14.9 mm ± 3.0 (p = 0.394). There was no difference between groups in total radiation time (navigation: 58.8 s ± 23.6, control: 56.5 s ± 28.5, p = 0.337) or radiation time during lag screw placement (navigation: 19.4 s ± 8.8, control: 18.8 s ± 8.0, p = 0.522). The surgical time was significantly longer in the computer-assisted navigation group with a mean surgical time of 45.8 min ± 9.8 compared to 38.4 min ± 9.3 in the control group (p = 0.009).ConclusionsComputer-assisted navigation consistently produced excellent TADs, however it was not significantly better than conventional methods when done by fellowship-trained orthopaedic traumatologists. Surgeons with a lower volume trauma practice could potentially benefit from computer-assisted navigation to obtain better TAD.     

Does an additional antirotation U-Blade (RC) lag screw improve treatment of AO/OTA 31 A1-3 fractures with gamma 3 nail?

IntroductionPoor bone quality and unstable fractures increase the cut-out rate in implants with gliding lag screws. The U-Blade (RC) lag screw for the Gamma3^® nail was introduced to provide monoaxial rotational stability of the femoral head and neck fragment. The purpose of this study was to evaluate whether the use of the U-Blade (RC) lag screw is associated with reduced cut-out in patients with OTA/AO 31A1-3 fractures.Material & methodsBetween 2009 and 2014, 751 patients with OTA/AO 31A1-3 fractures were treated with a Gamma3^® nail at our institution. Out of this sample 199 patients were treated with U-blade (RC) lag screws. A total of 135 patients (117 female, 18 male) with standard lag screw (treatment group A) were matched equally regarding age (±4 years) sex, fracture type and location to 135 patients with U-blade (RC) lag screw (treatment group B). Within a mean follow up of 9.2 months (range 6–18 months) we assessed the cut-out rate, the calTAD, lag screw migration, the Parker's mobility score and the Parker’s ratio at postoperatively, six and 12 months following surgery. Furthermore we recorded all complications, ASA-Score, hospital stay and duration of surgery retrospectively.ResultsThe most common fracture among group B with a cut-out of the lag screw were AO/OTA 2.3 and 3.2 fractures whereas in group A cut-out was most commonly seen in AO/OTA 2.1, 2.2 and 2.3 fractures, there was no significant reduction of the cut-out rate in group B 2.2% (n = 3) compared to group A 3.7% (n = 5). The duration of surgery was significantly shorter in group A (p < 0.05). There was no significant difference in lag screw placement, the Parker’s ratio and mobilization.ConclusionIn our study the U-Blade (RC) lag screw did not reduce the cut-out in treatment of OTA/AO 31A1-3 fractures at all. Considering the longer duration of surgery and the higher costs of the U-Blade (RC) lag screw, our results do not justify its use. However, further prospective randomized studies will be necessary.     

Radiological evaluation of intertrochanteric fracture fixation by the proximal femoral nail

BackgroundSuccessful treatment of intertrochanteric femoral fractures was reportedly influenced by the position of the fixation devices, by reduction quality and by fracture type.MethodsThe records of 227 patients with intertrochanteric fractures treated by intramedullary hip screws were analysed retrospectively. The angle and distance from the femur head apex were transformed into Cartesian coordinates. Comparisons were performed between patients with no mechanical failure (207 patients, 90.7%), with cutouts (15 patients, 6.6%) and with secondary loss of reduction (5 patients, 2.2%).ResultsThe standard tip apex distance (TAD) measurement above 25 mm did not predict failure (p = 0.62). Mechanical failure rates increased from 4.8% to 34.4% when the centre of lag screw was not in the second quarter of the head–neck interface line (the so-called “safe zone”) (p = 0.001). Lag screw insertion lower or higher than 11 mm of the head apex line were associated with failure rates of 5.5% and 18.6%, respectively (p = 0.004). Multivariate logistic regression showed that lag screw insertion not within the “safe-zone” was associated an Odds Ratio of 13.4 (95% CI 2.24–81) for mechanical failure (p = 0.004).ConclusionsThe TAD scale focuses on length measurement and lacks the vector properties of multidirectional measurements. Vector analysis revealed that the caudal-cranial correct lag screw position is the most important factor in preventing mechanical failure.     

Radiographic evaluation of first MTP joint arthrodesis for severe hallux valgus: Does the introduction of a lag screw improve union rates and correction of the intermetatarsal angle?

BackgroundFirst metatarsophalangeal (MTP-1) joint fusion is a reliable method for the correction of various deformities including hallux valgus and hallux rigidus. Ideal constructs provide high rates of fusion in desired alignment. The present study examines the union rates, as well as the change in dorsiflexion angle during the follow up period in patients who underwent MTP-1 fusion with a dorsal locking plate and a lag screw, versus patients fused with a dorsal locking plate alone.MethodsThis is a retrospective review of 99 feet undergoing MTP-1 fusion. Joints were fused using either a dorsal locking plate alone or a lag screw plus a dorsal locking plate. Union was determined radiographically during the follow up period. Suspected nonunions were confirmed with CT. Dorsiflexion angles were radiographically measured at first post-operative visit and at final follow up.ResultsThere were 36 patients in the lag screw plus dorsal plate group, and 63 in the dorsal plate group. Mean follow up was 12.9 months (Range: 12–33.5 months). The dorsal plate plus lag screw group had a significantly lower change in mean dorsiflexion angle (0.57° ± 5.01°) during the post-operative period compared to the dorsal plate group at final follow up versus the dorsal plate group (6.73° ± 7.07°).ConclusionThe addition of a lag screw to a dorsal locking plate for MTP-1 arthrodesis may offer improved stability of the joint in the sagittal plane over time compared to a dorsal plate alone.Level of evidenceRetrospective level III evidence.     

Prospective randomized study comparing two cephalomedullary nails for elderly intertrochanteric fractures: Zimmer natural nail versus proximal femoral nail antirotation II

ObjectivesAlthough both clinical and biomechanical studies suggest that cephalomedullary implants have a mechanical advantage over extramedullary implants, a high rate of complications or implant failure remains in elderly patients with osteoporosis. In an attempt to address some of these challenges, new implants with improved designs named proximal femoral nail antirotation II (PFNA II) and Zimmer natural nail (ZNN) were developed for elderly patients. Although the PFNA II reportedly has good clinical outcomes, it is unclear which implant achieves better safety and efficacy for treating intertrochanteric hip fractures. The primary objective of this prospective, randomized trial involved 353 patients was to evaluate Harris Hip Score (HHS). The secondary objective was to compare results associated with clinical outcome such as operation time, fluoroscopy time, lateral hip pain, walking ability, and reoperation rate as well as the incidence of cut-out by using implant position and fracture reduction quality.Methods353 patients with an intertrochanteric fracture amenable to either ZNN implant or PFNA II with a mean age of 77.0 years and a mean follow-up period of 12.3 months were included. We analyzed 353 patients with an intertrochanteric fracture treated using a ZNN implant (n = 172, group I) or a PFNA II (n = 181, group II) between January 2011 and August 2014.ResultsThere were no significant inter-group differences in HHS, walking ability, and reoperation rate were observed. However, operation and fluoroscopy time were significantly different between the two groups as well as group I showed a higher incidence of lateral hip pain than group II. In addition, no significant inter-group differences in cut-out rate determined by implant position and fracture reduction quality. We also found that cut-out was associated with lag screw position in the femoral head measured by Tip-apex distance (TAD) but not with reduction quality.ConclusionsAlthough group I had significant longer operation and fluoroscopy time than group II, both implants are useful tools in the treatment of elderly intertrochanteric fractures as well as only TAD, but not Cleveland zone significantly correlated with lag screw cut-out.     

Computational analysis of the safe zone for the antegrade lag screw in posterior column fixation with the anterior approach in acetabular fracture: A cadaveric study

ObjectiveThe fluoroscopically-guided procedure of antegrade posterior lag screw in posterior column fixation through anterior approach is technique-dependent and requires an experienced surgeon. The purpose of this study was to establish the safe zone for the antegrade posterior lag screw by using computational analysis.MethodThe virtual three-dimensional model of 178 hemi-pelvises was created from the CT data (DICOM format) by using Mimics^® program, and were used to measure the safe zone of antegrade lag screw fixation on the inner table of the iliac wing, and the largest diameter of cylindrical implant inside safe zone. The central point (point A) of the cylinder was assessed and was compared with the intersection point (point B) between the linea terminalis and the anterior border of the sacroiliac articulation.ResultsThe safe zone was triangular with an average area of 670.4 mm² (range, 374.8–1084.5 mm²). The largest diameter of the cylinder was a mean 7.4 mm (range, 5.0–10.0 mm). When height was under 156.3 cm, the diameter of the cylindrical implant was smaller than 7.0 mm (p < 0.001, regression coefficient = 0.09). The linear distance between points A and B was 32.5 mm (range, 19.2–49.3 mm). Point A was far enough away from the well-positioned anterior column plate to prevent collision between the two.ConclusionThe safe zone was shaped like a triangle, and was large enough for multiple screws. Considering the straight-line distance between points A and B, the central screw can be fixed without overlapping with the well-positioned anterior column plate at the point between holes 2 and 3.     

Additional vertebral augmentation with posterior instrumentation for unstable thoracolumbar burst fractures

BackgroundTo investigate the role of vertebral augmentation in kyphosis reduction, vertebral fracture union, and correction loss after surgical management of thoracolumbar burst fracture.DesignRetrospective chart and radiographic review.SettingLevel 1 trauma center.MethodsThe analysis included patients treated between April 2007 and June 2015, who received pedicle-screw-rod distraction and reduction within two days following acute traumatic thoracolumbar burst fracture with a load sharing score >6. Medical records were retrospectively reviewed for data regarding operative details, imaging and laboratory findings, neurological function, and functional outcomes.InterventionNot applicable.Main outcome measuresSagittal index, pain score, loss of correction, and implant failure rate.ResultsNineteen patients were enrolled in this study (mean age, 37.2 ± 13 years; age range, 17–62 years; female/male ratio: 10/9). Of the five patients who received only reduction (no augmentation), one underwent revision surgery because of implant failure and pedicle screw backing out. Compared to patients who received only reduction, those who received both reduction and augmentation showed better sagittal alignment after the operation, with better sagittal index immediately postoperatively and during the follow-up (p < 0.05).ConclusionsTranspedicular vertebral augmentation with calcium sulfate/phosphate-based bone cement may reinforce thoracolumbar burst fracture stability, partially restore vertebral body height, and reduce pedicle screw bending and movement, thereby preventing early implant failure and late loss of correction, especially in patients with excellent fracture reduction.Level of evidence: Therapeutic level III, retrospective chart review     

Expandable proximal femoral nail versus gamma proximal femoral nail for the treatment of AO/OTA 31A1-3 fractures

IntroductionThe gamma-proximal femoral nail (GPFN) and the expandable proximal femoral nail (EPFN) are two commonly used intramedullary devices for the treatment of AO 31A1-3 proximal femur fractures. The aim of this study was to compare outcomes and complication rates in patients treated by both devices.Patients and methodsA total of 299 patients (149 in the GPFN group and 150 in the EPFN group, average age 83.6 years) were treated for AO 31A1-3 proximal femur fractures in our institution between July 2008 and February 2013. Time from presentation to surgery, level of experience of the surgeon, operative time, amount of blood loss and number of blood transfusions were recorded. Postoperative radiological variables, including peg/screw location, tip to apex distance and orthopaedic complications, as, malunion, nonunion, surgical wound infection rates, cutouts, periprosthetic fractures and the incidence of non-orthopaedic complications. Functional results were estimated using the modified Harris Hip Score, and quality of life was queried by the SF-36 questionnaire.ResultsThe GPFN and the EPFN fixation methods were similar in terms of functional outcomes, complication rates and quality of life assessments. More patients (107 vs. 73) from the GPFN group were operated within 48 h from presentation (44.8 h vs. 49.9 h for the EPFN group, p = 0.351), and their surgery duration and hospitalisation were significantly longer (18.5 days vs. 26 days, respectively, p < 0.001). The GPFN patients were frequently operated by junior surgeons: 90% (135) while 50.6% (76) of the EPFN operations were performed by senior doctors. Other intraoperative measures were similar between groups. Cutout was the most common complication affecting 6.7% of the GPFN group and 3.3% of the EPFN group (p = 0.182).ConclusionsGood clinical outcomes and low complication rates in the GPFN and the EPFN groups indicate essentially equivalent safety and reliability on the part of both devices for the treatment of proximal femoral fractures.     

Computational simulation of cephalomedullary nailing in the osteoporotic Asian femur and clinical implications

PurposeTo assess the conformity of PFNA-II® and introduce clinical implications of new cephalomedullary nail (CMN) by analyzing three-dimensional (3D) modeling with virtual implantation at the actual size.Materials and methodsThirty-four patients (average age; 79 years, range 68–94 years) who sustained the intertrochanteric fracture of the femur were enrolled in the present study. After importing into Mimics® software, the intact femurs on the opposite side were selected as cropping areas to reconstruct the 3D femur model with the medullary canal. PFNA-II® and new CMNs (lateral angle 0° and 2°, CCD angle 130°; CMN0° and CMN2°) were processed at the actual size and ideally placed in the proximal femur using Mimics® software. The virtual entry point (EP), nail conformity, and anatomical relationships with the adjacent structures were assessed.ResultsThe virtual EP of PFNA-II® was placed along the cervico-trochanteric (CT) junction in the posterior half around trochanteric fossa and always medial to the tip of greater trochanter (GT). There were six abutments in PFNA-II® models, one impingement in CMN 0°, and no impingement in CMN 2°. All the models with cortical abutment showed increased anterior and lateral bowing of the proximal shaft owing to age-dependent changes. Compared with PFNA-II®, with a decreasing tendency on the mediolateral angle of new CMNs, the virtual EP shifted to the medial and anterior side towards the CT junction. By simulating the intentional positioning in the media-to-lateral direction, the abutments in the PFNA-II® model could not be avoided. Furthermore, the lag screw of CMN 0° was placed ideally at the center or inferior side of the femoral head < 10 mm in any direction without a cortical abutment.ConclusionTo avoid cortical abutment of CMN in the Asian geriatric femur, the virtual EP would be technically placed in the medial to the GT tip, and the implant design should be changed to decrease the mediolateral angle.     

Risk factors of avascular necrosis of the femoral head and fixation failure in patients with valgus angulated femoral neck fractures over the age of 50 years

IntroductionThe aim of our study was to identify the risk factors for avascular necrosis of the femoral head (AVN) and fixation failure (FF) after screw osteosynthesis in patients with valgus angulated femoral neck fractures.Patients and methodsWe conducted a retrospective study of 308 patients (mean age, 72.5 years, range, 50–97 years), with a mean follow-up of 21.4 months (range, 12–64 months). The risk for failure in treatment (FIT) associated with patient- and fracture-related factors was evaluated by logistic regression analyses.ResultsFIT was identified in 32 cases (10.3%): 22 cases (7.1%) of AVN and 10 cases (3.2%) of FF. Initial valgus tilt > 15° (p = 0.023), posterior tilt > 15° (p = 0.012), and screw sliding distance (p = 0.037) were significantly associated with FIT. FIT occurred in 7 patients (5.2%) with B1.2.1 fractures and 17 patients (48.6%) with B1.1.2 fractures (p < 0.001). The odds of FIT were 17-fold higher in patients with initial valgus and posterior tilts > 15° (B1.1.2) compared to patients with <15° of tilt in both planes (B1.2.1).ConclusionThe severity of initial deformity predicts AVN and FF in patients with valgus angulated femoral neck fractures. Patients with an initial valgus and posterior tilt > 15° are reasonable candidates for primary arthroplasty due to high risk of FIT.     

Fixation of displaced femoral neck fractures in young adults: Fixed-angle devices or Pauwel screws?

BackgroundWe sought to compare the incidence of complications after fixation of displaced femoral neck fractures in young adults treated with fixed-angle devices versus multiple cancellous screws and a trochanteric lag screw (Pauwel screw).MethodsWe conducted a retrospective cohort study at a level I trauma centre. Sixty-two skeletally mature patients (age range, 16–60 years) with displaced femoral neck fractures were included in the study. Forty-seven were treated with a fixed-angle device (sliding hip plate with screw or helical blade) and 15 with multiple cancellous screws placed in a Pauwel configuration. The main outcome measure was postoperative complication of osteonecrosis or nonunion treated with a surgical procedure.ResultsSignificantly fewer failures occurred in the fixed-angle group (21%) than in the screws group (60%) (p = 0.008). Osteonecrosis was rare in the fixed-angle group, occurring in 2% of cases versus 33% of cases in the screws group (p = 0.002). Consistent with previous studies, good to excellent reductions were associated with a failure rate of 25% and fair to poor reductions were associated with a failure rate of 55% (p = 0.07). The best-case scenario of a good to excellent reduction stabilised with a fixed-angle device yielded a success rate of 85%.ConclusionIn young patients with displaced high-energy femoral neck fractures, fixed-angle devices resulted in fewer treatment failures than did Pauwel screws.     

Risk factors for cut-out of double lag screw fixation in proximal femoral fractures

ObjectiveWe assessed factors associated with cut-out after internal fixation of proximal femoral fractures using double lag screw nails.DesignRetrospective cohort study.SettingA university hospital.Patients and methodsPatients with non-pathological intertrochanteric femur fractures and a minumum 90 days follow-up who underwent internal fixation with dual lag screw nails were included. Potential risk factors for lag screw cut-out investigated by our study were: age, gender, body mass index, comorbidities (American Society of Anesthesiologists [ASA] classification), type of fracture (AO/OTA classification), fracture stability, side, operation time, implant length, reduction quality, tip-apex distance (TAD), and lag screw configuration. Logistic regression was used to investigate potential predictors of screw cut-out.ResultsEighty-five of the 118 patients with hip fractures treated between February 2010 and November 2013 at our institution met the inclusion criteria for the study. Fifty-eight patients were female (68.2%), mean age was 77.4 (range: 50–95 years), mean follow up was 380 days (range: 150 days-2.5 years), and cut of was observed in 9 patients (10.5%). The following variables identified through univariate analysis with p < 0.2 were included in multivariant logistic regression model: age, side, reduction quality, implant length, TAD and ASA score. Only TAD (p = 0.003) was found to be significant in the multivariant model.ConclusionsOur study confirmed that risk factors for cut-out with single-lag screw devices are also applicable to dual-lag screw implants. We found that TAD was a significant factor for cut-out in dual-lag screw implants. Thus, screw cut-out can be minimized by optimizing screw position.     

Internal fixation versus conservative treatment for elderly patients with a trochanteric hip fracture in conjunction with post-stroke hemiplegia

ObjectiveTo retrospectively evaluated Gamma nail internal fixation in the treatment of elderly patients with post-stroke hemiplegia experiencing trochanteric hip fracture.MethodsThe patients were obtained consecutively from January 2005 to December 2010 with inclusion criteria. The total number was 138 and allocated to two groups: treated with the Gamma nail (n = 72,group A) and continuous skin traction (n = 66,group B). Preoperative variables including patient age, gender, duration of cerebrovascular accident, duration of hypertension, ASA risk score, Harris hip score and fracture type were recorded and compared. After treatment, time of patients activity on the bed, ambulation time, Harris hip score, mortality, complications were recorded and used to compare the outcomes.Results(1) Follow-up was undertaken from 3 to 10 years, with an average of 5.8 years. (2) No statistical difference in preoperative variables was found between the 2 groups. (3) two groups had statistical significance (P = 0.000) in the time of patients activity on the bed and ambulation time and group A can activities on the bed and ambulates earlier. (4) There were significant differences between 2 groups in Harris hip score at 1 and 3 years and group A was significantly higher than group B. (5) there were statistically significant differences in mortality of 3 years, 5 years and 10 years and the group B was significantly higher than the group A. (6) There was a statistical significance in complications between 2 groups and group B was higher than group A. Major complications in group A were pain, lag screw cut out, implant infection and distal femoral fractures caused by fall after the surgery.ConclusionOn elderly patients with trochanteric hip fracture on the hemiplegic lower side, Gamma nail internal fixation treatment can achieve better effect, patients can be early activity, fewer complications, and less mortality.     

Biomechanical analysis of peri‑implant fractures in short versus long cephalomedullary implants following pertrochanteric fracture consolidation

IntroductionPertrochanteric femur fracture fixation with use of cephalomedullary nails (CMN) has become increasingly popular in recent past. Known complications after fracture consolidation include peri‑implant fractures following the use of both short and long nails, with fracture lines around the tip of the nail or through the interlocking screw holes, resulting in secondary midshaft or supracondylar femur fractures, respectively. Limited research exists to help the surgeon decide on the use of short versus long nails, while both have their benefits. The aim of this biomechanical study is to investigate in direct comparison one of the newest generations short and long CMNs in a human anatomical model, in terms of construct stability and generation of secondary fracture pattern following pertrochanteric fracture consolidation.MethodsEight intact human anatomical femur pairs were assigned to two groups of eight specimens each for nailing using short or long CMNs. Each specimen was first biomechanically preloaded at 1 Hz over 2000 cycles in superimposed synchronous axial compression to 1800 N and internal rotation to 11.5 Nm. Following, internal rotation to failure was applied over an arc of 90° within one second under 700 N axial load. Torsional stiffness as well as torque at failure, angle at failure, and energy to failure were evaluated. Fracture patterns were analyzed.ResultsOutcomes in the study groups with short and long nails were 9.7 ± 2.4 Nm/° and 10.2 ± 2.9 Nm/° for torsional stiffness, 119.8 ± 37.2 Nm and 128±46.7 Nm for torque at failure, 13.5 ± 3.5° and 13.4 ± 2.6° for angle at failure, and 887.5 ± 416.9 Nm° and 928.3 ± 461.0 Nm° for energy to failure, respectively, with no significant differences between them, p ≥ 0.17. Fractures through the distal locking screw holes occurred in 5 and 6 femora instrumented with short and long nails, respectively. Fractures through the lateral entry site of the head element were detected in 3 specimens within each group. For short nails, fractures through the distal shaft region, not interfacing with the implant, were detected in 3 specimens.ConclusionFrom a biomechanical perspective, the risk of secondary peri‑implant fracture after intramedullary fixation of pertrochanteric fractures is similar when using short or long CMN. Moreover, for both nail versions the fracture pattern does not unexceptionally involve the distal locking screw hole.     

Surgical tips of intramedullary nailing in severely bowed femurs in atypical femur fractures: Simulation with 3D printed model

IntroductionThe surgical management of atypical femoral fractures (AFFs) is complex in cases with severe bowing of the femur, being associated with a high rate of failure. Our first aim was to use preoperative templating and 3D printed model characterise the technical difficulties associated with use of current commercially available intramedullary nail (IMN) systems for the management of AFFs with severe bowing. Our second aim was to use outcomes of our 3D printing analysis to define technical criteria to overcome these problems.Material and MethodsThe modelled femur with 3D printing had an anterior bowing curvature radius of 772 mm and an angle of lateral bowing of 15.4°. Nine commercially available IMN systems were evaluated in terms of position of the nail within the medullary canal, occurrence of perforation of femoral cortex by the distal tip of the nail, and location of the site of perforation relative to the knee joint. The following IMN systems were evaluated: unreamed femoral nail (UFN), cannulated femoral nail (CFN), Sirus nail, right and left expert Asian femoral nail (A2FN), right and left Zimmer Natural Nail (ZNN), proximal femoral nail anti-rotation (PFNA), and Zimmer Cephalomedullary Nail (CMN).ResultsAlong the sagittal plane, the UFN, CFN and Sirus systems were acceptably contained within the medullary canal, as well as the “opposite side” A2FN and ZNN. Only the Sirus IMN system was contained along the coronal plane. The distal part of the all other IMN systems perforated the anterior cortex of the femur, at distances ranging between 2.8 and 11.7 cm above the distal end of the femoral condyles. Using simulated fracture reduction in the 3D printed model, none of the 9 IMN systems provided acceptable anatomical reduction of the fracture. A residual gap in fragment position and translation was provided by the “opposite side” ZNN, followed by the UFN and Sirus systems.ConclusionCommercially available IMN systems showed mismatch with severely bowed femurs. Our simulation supports that fit of these systems can be improved using an IMN system with a small radius of curvature and diameter, and by applying specific operative procedures.     

A mathematical simulation of the tip-apex distance and the calcar-referenced tip-apex distance for intertrochanteric fractures reduced with lag screws

BackgroundAs a predictor of the risk of lag screw cutout, it was recommended that keeping tip-apex distance (TAD) < 25 mm and placing the screw centrally or inferiorly, but positioning the lag screw too inferiorly in the head would produce TAD > 25 mm. We aim to simulate various positions of the lag screw in the femoral head and identify whether 25 mm is a suitable cut-off value that favours all sizes of femoral heads with intertrochanteric fractures of the hip.MethodsUsing a general mathematical software, the positions of the screw tip points were simulated. The virtual anterior–posterior and lateral views were then visualised, and the locus of the screw tips was projected into a Cartesian coordinate system according to the TAD and calcar-referenced tip-apex distance (CalTAD) formulas. Each original virtual anterior–posterior and lateral image was zoomed and compiled to match a calculated average image. The screw tip points were recorded, traced and compiled into volumes which could be used to visualise the screw's movements and positioning within the femoral head. The extracted volumes were calculated when 10 mm < TAD < 25 mm and 10 mm < CalTAD < 25 mm, and the region where these two volumes overlapped was also calculated. Suitable positions for the screw tip were then assessed.ResultsFor the TAD calculation, the shape of the traced screw tip points had a pancake-like appearance, while the CalTAD plot produced a teardrop-shaped region. The volume ratios of TAD, CalTAD and overlapping region relative to the femoral head volume were respectively 3.51 ± 1.30%, 5.19 ± 1.62% and 2.64 ± 1.32%. The volumes of the traced TAD, CalTAD and overlapping regions increased slower than the volume of an idealised sphere.ConclusionPositioning the lag screw should address geometrical effects of both tip-apex distance and femoral head size, with an emphasis on measuring the position of the screw tip for the suitable zone by volume ratio. The previous 25 mm TAD cut-off value should be adjusted according to the individual femoral head size.     

The results of tension band rotator cuff suture fixation of locked plating of displaced proximal humerus fractures

IntroductionThe purpose of this study was to assess 1-year outcomes of patients with displaced proximal humerus fractures who underwent treatment with locked plate fixation with rotator cuff suture augmentation.MethodsA total of 86 patients who had sustained 2, 3 and 4-part displaced proximal humerus fractures underwent locked plate fixation with multiple sutures placed in the cuff tendons. Clinical outcome variables included active forward elevation (AFE), active external rotation (AER), and Constant and American Shoulder and Elbow Surgeons (ASES) scores. Post-operative variables included the following complications: varus re-collapse, loss of fixation, osteonecrosis of the humeral head (AVN), screw cut out, hardware failure and infection.ResultsForty-one patients were available with minimum of 1-year follow-up. Mean AFE was 142 ± 17.0° and AER was 41 ± 13.0°. The overall complication rate was 14.6%, with osteonecrosis being the most common (12.2%). Of the 21 patients (51.2%) that initially had varus displacement, all but one maintained anatomic reduction and fixation. Mean ASES score was 78.2 ± 20.0 and average Constant score was 72.7 ± 17.6. Bivariate analyses demonstrated that pre-operative medial comminution (p = 0.297) or varus collapse (p = 0.95) were not associated with an increased likelihood of sustaining a complication.ConclusionsFollow-up of patients in this series demonstrated a low overall complication rate and excellent functional outcomes. We believe suture augmentation of the rotator cuff can counteract varus forces on proximal humerus fractures fixed with locked plates, and should be performed routinely in displaced 2, 3 and 4 part fractures.     

What is the most fixable intramedullary implant for basicervical fracture and transcervical shear fracture? – A finite element study

ObjectiveThe objectives of this study are 1) to biomechanically compare six different intramedullary fixations for basicervical fracture (AO 31-B3, Type 2 in area classification) and transcervical shear fracture (AO 31-B2.3, Type 1–2 in area classification) using the finite element (FE) method, and 2) to investigate the effects of two different unstable fracture types on fixation.MethodsFE models of two different types of proximal femoral fractures are constructed from CT scan images of a patient with osteoporosis. The fracture models are fixed with a short femoral nail with a single lag screw, short femoral nail with a single blade, and short femoral nail with double lag screws, and then fixed with long femoral nails for each of the three nail types. Subsequently, the maximum loads during walking and stair climbing, as well as the minimum principal strain and compressive failure elements are calculated to assess the fixation of each implant.ResultsIn both fracture types, the long nail with double lag screws show the smallest volume of compressive failure elements (basicervical fracture, 2 mm³; transcervical shear fracture, 217 mm³). In all types of implants, the volume of the compressive failure elements is larger in the transcervical shear fracture than in the basicervical fracture. A similar trend is observed for the minimum principal strain (compressive strain).ConclusionThe present study shows that a long nail with double lag screws is the most fixative intramedullary nail device for basicervical fracture and transcervical shear fracture in any condition. Furthermore, it is shown that transcervical shear fracture is considerably more unstable than basicervical fracture.     

Radiographic predictors of symptomatic screw removal after retrograde femoral nail insertion

IntroductionRemoval of symptomatic implants is a common procedure performed by orthopaedic trauma surgeons. No guidance is available regarding which factors contribute to the likelihood of an implant becoming symptomatic. Our objective was to determine whether radiographic parameters associated with distal interlocks in retrograde femoral nails are associated with the rate of symptomatic screw removal.Patients and methodsWe conducted a retrospective review at a Level I trauma center. Study patients (n = 442) had femoral fractures treated with retrograde intramedullary nails from 2007 to 2014 and at least 1 year of follow-up. The main outcome measurement was symptomatic distal screw removal as predicted by radiographic parameters.ResultsSymptomatic screw removal occurred in 12% of the patients. Increased distance between the most distal screw and the articular surface of the femur significantly reduced likelihood of symptomatic screw removal. A cutoff of 40 mm from the articular block was predictive of removal (≥40 mm, 0% removal; <40 mm, 18% removal, p < 0.0001). In patients with distal screws placed within 40 mm of the articular surface of the femur, a ratio of screw length to distance between medial and lateral femoral cortices that was ≥1 was a strong predictor of symptomatic screw removal (area under Receiver Operating Characteristic curve, 0.75; p < 0.0001).ConclusionsMore distal screws and screws that radiographically extend to or beyond the medial cortex are more likely to cause pain and require removal in femoral fractures treated with retrograde intramedullary nails. We identified a specific distance from the joint (<40 mm) and a ratio of screw length to bone width (≥1) that significantly increased the likelihood of symptomatic screw removal. Clinicians can use these data to inform patients of the likely risk of implant removal and perhaps to better guide placement and length of screws when the clinical scenario allows some flexibility in location and length of screws.     

Expert tibia nail for subtrochanteric femoral fracture to prevent thermal injury

IntroductionSubtrochanteric femoral fractures are relatively uncommon, accounting for 7–15% of all hip fractures and treatment of these fractures are considered challenge for orthopaedic surgeons. Although several treatment options are reported with up to 90% of satisfactory results, the choice of the appropriate implant is still a matter of debate. Some authors reported thermal injury after reaming for intramedullary nail fixation in patients with narrow medullary canal.Presentation of caseA 21-year-old female patient was admitted to our hospital because of right subtrochanteric femoral fracture. The narrowest diameter of medullary canal of her femur was about 7 mm but she refused open reduction and internal fixation with plate due to large scar formation. We used expert tibia nail instead of femoral intramedullary nail to prevent thermal injury.DiscussionSubtrochanteric femoral fractures are difficult to treat because of their biomechanical and anatomical characteristics. Although several implants are reported for the surgical treatment of these fractures, intramedullary nails have been advocated due to their biological and biomechanical advantages. However, under certain circumstances with associated injury or anatomic difference we might consider another treatment options.ConclusionExpert tibia nail may be considered one of the treatment options for subtrochanteric femoral fracture with narrow medullary canal. We also emphasize the importance of preoperative evaluation of the medullary canal size for these risky fractures.