Forces required to dynamize sliding screws in gamma nail and selfdynamizable internal fixator

BACKGROUND

Single limb support phase of the gait-cycle in patients who are treated for a pertrochanteric fracture is characterized by transversal loads acting on the lag screw, tending to block its dynamization. If the simultaneous axial force overcomes transversal loads of the sliding screw, the dynamization can still occur.

METHODS

Biomechanical investigation was performed for three types of dynamic implants: Gamma Nail, and two types of Selfdynamizable Internal Fixators (SIF) - SIF-7 (containing two 7 mm non-cannulated sliding screws), and SIF-10 (containing one 10 mm cannulated sliding screw). Contact surface between the stem and the sliding screws is larger in SIF implants than in Gamma Nail, as the stem of Gamma Nail is hollow. A special testing device was designed for this study to provide simultaneous application of a controlled sliding screws bending moment and a controlled transversal load on sliding screws (Qt) without using of weights. Using each of the implants, axial forces required to initiate sliding screws dynamization (Qa) were applied and measured using a tensile testing machine, for several values of sliding screws bending moment. Standard least-squares method was used to present the results through the linear regression model.

RESULTS

Positive correlation between Qt and Qa was confirmed (p < 0.05). While performing higher bending moments in all the tested implants, Qa was higher than it could be provided by the body weight. It was the highest in Gamma Nail, and the lowest in SIF-10.

CONCLUSIONS

A larger contact surface between a sliding screw and stem results in lower forces required to initiate dynamization of a sliding screw. Patients treated for a pertrochanteric fracture by a sliding screw internal fixation who have longer femoral neck or higher body weight could have different programme of early postoperative rehabilitation than lighter patients or patients with shorter femoral neck.

Effect of lag screw on stability of first metatarsophalangeal joint arthrodesis with medial plate

Background

First metatarsophalangeal joint (MTP-1) arthrodesis is a commonly performed procedure in the treatment of disorders of the great toe. Since the incidence of revision after MTP-1 joint arthrodesis is not insignificant, a medial approach with a medially positioned locking plate has been proposed as a new technique. The aim of the study was to investigate the effect of the application of a lag screw on the stability and strength of first metatarsophalangeal joint arthrodesis with medial plate.

Methods

The bending tests in a testing machine were performed for models of the first metatarsal bone and the proximal phalanx printed on a 3D printer from polylactide material. The bones were joined using the locking titanium plate and six locking screws. The specimens were divided into three groups of seven each: medial plate and no lag screw, medial plate with a lag screw, dorsal plate with a lag screw. The tests were carried out quasi-static until the samples failure.

Results

The addition of the lag screw to the medial plate significantly increased flexural stiffness (41.45 N/mm vs 23.84 N/mm, p = 0.002), which was lower than that of the dorsal plate with a lag screw (81.29 N/mm, p < 0.001). The similar maximum force greater than 700 N (p > 0.50) and the relative bone displacements lower than 0.5 mm for a force of 50 N were obtained for all fixation techniques.

Conclusions

The lag screw significantly increased the shear stiffness in particular and reduced relative transverse displacements to the level that should not delay the healing process for the full load of the MTP-1 joint arthrodesis with the medial plate. It is recommended to use the locking screws with a larger cross-sectional area of the head to minimize rotation of the medial plate relative to the metatarsal bone.

A case of total hip arthroplasty for nonunion after femoral trochanteric fracture surgery with complete breakage of only the compression screw of the InterTAN nail

Intramedullary nails are an effective treatment for common femoral trochanteric fractures. However, one of their complications is implant breakage due to poor reduction and nonunion after surgery. We herein report a case of a 54-year-old man who underwent total hip arthroplasty for nonunion after internal fixation of a femoral trochanteric fracture. The femoral trochanteric fracture was treated by internal fixation using the Trigen InterTAN nail. The patient developed symptoms of hip pain 6 months after internal fixation. Nine months after internal fixation, hip radiographs and computed tomography scans showed breakage of only the compression screw. During total hip arthroplasty, we were unable to remove the lag screw and compression screw before the femoral head dislocation because no gap was present between the two screws. Thus, we removed these screws with the femoral head after dislocation of the femoral head. The removed nail was partially damaged at the lag screw hole. This change was retrospectively observed on the preoperative computed tomography scan. Three months after total hip arthroplasty, the patient was able to walk unaided and the hip pain had resolved. If only the compression screw is completely broken after internal fixation with the Trigen InterTAN nail, both the lag screw and compression screw will be difficult to remove with preservation of the femoral head. We effectively managed such a case by not only revision internal fixation but also total hip arthroplasty.

Augmentative lag screws as a treatment for aseptic hypertrophic nonunion after internal fracture fixation

BACKGROUND

Hypertrophic nonunion after intramedullary (IM) nailing and plating is Uncommon and the treatment remained controversial. The aim of this study was to show the result of a simple augmentative lag screws technique for vital non-unions after internal fixation PATIENTS AND METHODS: We retrospectively reviewed the patients with nonunion after internal fixation between January 2016 to August 2022. Patients with unacceptable shortening or deformity were excluded as well as nonunion septic cases. All the patients were followed up for at least 6 months.

RESULTS

Seven patients achieved bony union in a median time of 12 weeks (IRQ 12-16). There was a failure case with persistent non-union and brokerage of the screws.

DISCUSSION

Various techniques have been described to treat non-union after intramedullary nailing or plating. The existing nail is frequently removed, and the non-union site is either re-reamed and re-nailed or fixed with a plate or external fixation devices or rechanged by a nail in the case of plates. In our study of non-union, augmentative lag screws were successfully applied to treat eight patients with aseptic nonunion, resulting in the healing of non-union in all cases except one.

CONCLUSION

Augmentative lag screws represent a simple technique for the management of aseptic hypertrophic nonunion after internal fixation with a significantly shorter operating time.

Biomechanics of sacroiliac joint fixation using lag screws: a cadaveric study

BACKGROUND

Iliosacral screw placement is ubiquitous and now part of the surgeon's pelvic trauma armamentarium. More recent evidence supports sacroiliac arthrodesis for treating sacroiliac joint (SIJ) dysfunction in select patients. Regardless of the surgical indication, there are currently no studies examining lag screw compression biomechanics across the SIJ. The objective of this biomechanical investigation was to quantify iliosacral implant compressive loads and to examine the insertion torque and compressive load profile over time.

METHODS

Eight human cadaveric pelvic specimens underwent SIJ fixation at S1 and S2 using 11.5 and 10.0 mm iFuse-TORQ Lag implants, respectively, and standard 7.3 mm trauma lag screws. Load decay analysis was performed, and insertion and removal torques were measured.

RESULTS

For both implants at S1 and S2 levels, the load relaxed 50% in approximately 67 min. Compressive load decay was approximately 70% on average occurring approximately 15 h post-insertion. Average insertion torque for the 11.5 mm TORQ implant at S1 was significantly greater than the trauma lag screw. Similarly, at S2, insertion torque of the 10.0 mm TORQ implant was greater than the trauma lag screw. At S1, removal torque for the 11.5 mm TORQ implant was higher than the trauma lag screw; there was no significant difference in the removal torque at S2.

CONCLUSIONS

In this study, we found that a novel posterior pelvic implant with a larger diameter, roughened surface, and dual pitch threads achieved improved insertion and removal torques compared to a standard screw. Load relaxation characteristics were similar between all implants.

[Effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture]

OBJECTIVE

To analyze the effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture.

METHODS

From January 2016 to June 2021, 26 patients with Ideberg typeⅡglenoid fractures were treated with trans-axillary lag screw combined with supporting plate, including 15 males and 11 females. The age ranged from 21 to 75 years, with an average of (43.12±6.56) years old. The Constant-Murley Shoulder joint Scale and University of California at Los Angeles (UCLA) score were used to evaluate the function and clinical efficacy of shoulder joint.

RESULTS

All patients were followed up, and the duration ranged from 19 to 42 months, with an average of (30.6±10.5) months. One year after surgery, the Constant-Murley score increased from preoperative 34.9±2.5(ranged, from 28 to 47) to 87.2±6.8(ranged, from 70 to 95). The UCLA score improved from preoperative 17.9±1.7(9 to 25) to 33.1±2.3(29 to 35). Seventeen patients got an excellent result, with 7 good, and 2 fair. None of the patients had infection, screw, and plate loosening, fracture, and other complications after surgery. Two patients had different degrees of Chronic pain in the shoulder during the follow-up period.

CONCLUSION

The treatment of Ideberg typeⅡscapular glenoid fractures through axillary approach with lag screws and supporting steel plates has the advantages of convenient exposure, direct visual restoration of the normal anatomical shape of the scapular glenoid, selection of suitable positions for screw and steel plate placement, achieving better treatment results, and fewer complications. It is an effective and reliable surgical method.

Proposal of a modified tip apex distance for prediction of lag screw cut-out in trochanteric hip fractures

INTRODUCTION

Lag screw cut-out is a serious complication of dynamic hip screw fixation of trochanteric hip fractures. The lag screw position has been acknowledged as one of the important factors affecting the lag screw cut-out. We propose a modification of the Tip Apex Distance (TAD) and hypothesise that it could improve the reliability of predicting lag screws cut-out in these injuries.

MATERIALS AND METHODS

A retrospective study was conducted for hip fracture entries in the period from Jan 2018 to July 2022. A hundred and nine patients were suitable for the final analysis. The modified TAD was measured in millimetres based on the sum of the traditional TAD in the lateral view and the net value of two distances in the AP view, the first distance is from the tip of the lag screw to the opposite point on the femoral head along the axis of the lag screw while the second distance is from that point to the femoral head apex. The first distance is a positive value, whereas the second distance is positive if the lag screw is superior and negative if inferior. A receiver operating characteristic curve was used to evaluate the reliability of the different parameters assessing the lag screw position within the femoral head.

RESULTS

Reduction quality, fracture pattern as per the AO/OTA classification, TAD, Calcar Referenced TAD, Axis Blade Angle, Parker's ration in the AP view, Cleveland Zone 1, and modified TAD were statistically associated with lag screw cut-out. Among the tested parameters, the modified TAD had 90.1% sensitivity and 90.9% specificity for lag screw cut-out at a cut-off value of 25 mm with a P-value < 0.001.

CONCLUSION

The modified TAD had the highest reliability in the prediction of lag screw cut-out. A value ≤ 25 mm could potentially protect against lag screw cut-out in trochanteric hip fractures.

No effect of hydroxyapatite-coated sliding hip screw threads on screw migration in the femoral head/neck of pertrochanteric fractures: a randomized controlled trial using radiostereometric analysis

INTRODUCTION

Cut-out is the most frequently reported mechanical failure of internal fixation of pertrochanteric fractures. The purpose of this study was to examine if hydroxyapatite-coated screw thread on a sliding hip screw (SHS) could reduce screw migration within the femoral head in patients with stable pertrochanteric fractures.

MATERIALS AND METHODS

In a double-blinded randomized controlled study, 37 patients at mean age 78 (range 56-96), with pertrochanteric fracture (Evans I, II, IV) received surgery with a SHS with a hydroxyapatite-coated or a non-coated lag screw thread. Radiostereometry and standard radiographs were obtained 1 day, 6 weeks, 3- and 6 months post-operatively to evaluate screw and fracture migration and fracture reposition. The two groups were combined to describe fracture migration.

RESULTS

There was similar and small screw migration in the femoral head between the two groups at 6 weeks, 3- and 6 months (p > 0.12). Fracture migration occurred predominantly in the first 6 weeks, where fracture impaction was 5.95 mm (CI 95% 2.87 to 9.04) and anterior rotation of the femoral head was -2.94° (CI 95% - 5.22 to - 0.66). Migration of the fracture (total translation) correlated to the post-operative fracture reposition (p = 0.002), but not significantly to screw migration (p = 0.09). Neither screw total translation (rho 0.06, p = 0.79) nor fracture total translation (rho 0.04, p = 0.77) correlated with bone mineral density.

CONCLUSION

There was no clinical benefit of hydroxyapatite coating on lag screw migration in this patient cohort. Migration of the pertrochanteric fractures was higher with poor fracture reposition but fractures generally stabilized after 6 weeks follow-up. The study was registered at ClinicalTrials.gov (NCT05677061).

LEVEL OF EVIDENCE II

Patient-blinded prospective randomized study. Trial registration number The study was registered at ClinicalTrials.gov (NCT05677061).

Endovascular assisted removal of intrapelvic lag screw after intramedullary proximal femoral nail: A case report and literature review

Background

Trochanteric fractures are very common hip injuries often fixed with intramedullary nailing as the recommended treatment. Medial lag screw migration of the intramedullary nail system is an uncommon complication. The objective of this case report is to highlight the importance of optimal reduction in hip fractures and the need for a multidisciplinary approach with vascular assistance in intrapelvic lag screw migration.

Case report and results

We collected 24 cases of intrapelvic migration of the lag screw in the latest literature. Here, we report the case of a 68-year-old patient with medial pelvic migration of the lag screw after minor trauma and its removal using peroperative simultaneous angiography. After removal of the osteosynthesis material, a revision to a total hip arthroplasty was performed.

Conclusion/discussion

This is the first case demonstrating an endovascular assisted removal simultaneous with revision surgery. We suggest that a multidisciplinary approach is warranted in which the orthopedic surgeon is assisted by a vascular surgeon. An endovascular assisted open removal of the lag screw with conversion to a hip arthroplasty is considered a safe treatment.

Which head element is more effective for cement augmentation of TFNA? Helical blade versus lag screw

BACKGROUND

Early fixation and rehabilitation is the gold standard treatment for intertrochanteric femur fractures. Cement augmentation through perforated head elements has been developed to avoid postoperative complications such as cut-out or cut-through. The purpose of this study was to compare two head elements in terms of cement distribution using computed tomography (CT) and to examine their initial fixation and clinical outcomes.

METHODS

Elderly patients who had intertrochanteric fractures were treated with a trochanteric fixation nail advanced (TFNA) helical blade (Blade group) or a TFNA lag screw (Screw group). In both groups, 4.2 mL of cement was injected under an image intensifier (1.8 mL of cement was directed cranially and 0.8 mL each caudally, anteriorly, and posteriorly). Patient demographics and clinical outcome were investigated post-operatively. Cement distribution from the center of the head element was evaluated with CT. Maximum penetration depth (MPD) were measured in the coronal and sagittal planes. On each axial plane, the cross-sectional areas in the cranial, caudal, anterior and posterior directions were calculated. The sum of cross-sectional areas (successive 36 slices) was defined as the volume of the head element.

RESULTS

The Blade group included 14 patients, and the Screw group included 15 patients. In the Blade group, MPD in the anterior and caudal direction was significantly greater than that in the posterior direction (p < 0.01). In the Screw group, volume in the cranial and posterior direction was significantly greater than that in the Blade group (p = 0.03). Subsequently, the total volume in the Screw group was significantly larger than that in the Blade group (p < 0.01). No significant correlation was detected between bone mineral density, T score, young adult mean, and total cement volume. Change in radiographic parameters and clinical outcome such as Parker score and visual analog scale were similar in both groups. No patients suffered from cut-out / cut through or non-union.

CONCLUSIONS

The position of cement distribution through the lag screw is different from that through the helical blade, and the total volume of the head element is significantly larger in the lag screw. Both groups had similarly effective results in terms of mechanical stability after surgery, postoperative pain and early phase of rehabilitation.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN45341843, 24/12/2022, Retrospectively registered.

Double lag-screw compression for optimal fixation of intertrochanteric fractures with large fragment gap: A technical note

Cephalomedullary nailing of unstable intertrochanteric fractures has been established as a fruitful surgical approach with relatively limited complications. Anatomic fracture reduction and proper implant positioning are vital to attaining a favorable long-term surgical outcome. Appropriate intraoperative fracture compression augments stability and invigorates healing. The amount of compression permitted by cephalomedullary nails cannot always adequately reduce large fragment gaps. This paper presents a novel technical trick of double compression of the fracture site, in order to achieve the essential extra compression and reduction when required, thus decreasing the risk of postoperative implant cut-out. The technique was used in 14 out of 277 peritrochanteric fractures treated with cephalomedullary nailing in our trauma center for 12 months, with satisfactory outcomes regarding both fracture site union and postoperative functional capacity.

Comparison of mid-term clinical results between lag screw fixation and Kirschner wire fixation after close reduction in adolescent triplane distal tibia epiphyseal fracture

OBJECTIVE

To compare the mid-term clinical results of lag screw and Kirschner wire fixation(KWF) for close reduction in triplane distal tibia epiphyseal fracture.

METHODS

A retrospective analysis of 25 cases of triplane fractures of the distal tibia treated in our department from Jan 2017 to Dec 2019 was performed, Lag screw fixation(LSF) was used in 14 cases and Kirschner wire fixation in 11 cases, the clinical results were evaluated by premature epiphyseal closure(PPC) rate, the American Orthopaedic Foot and Ankle Score (AOFAS) Ankle-hindfoot foot scoring system, the lateral distal tibial angle (LDTA) from X-ray.

RESULTS

All the 25 children were followed up for a mean of 34(ranging 26-52) months. AOFAS scores improved from a mean of 33(ranging 29-43) pre-op, to 82(ranging 77-88) at three month follow up, to 92 (ranging 88-98) at last follow-up in all 25 cases. Till last follow up there was no cases premature physeal closure in LSF group but 4 cases in KWF group, LDTA in both groups at last follow up shows no ankle varus or valgus deformity, and the ankle joint function was not limited in all cases.

CONCLUSION

Lag screw and Kirschner wire fixation methods can both achieve good clinical effects for triplane distal tibia epiphyseal fracture. Lag screw fixation provide lower PPC rate but Kirschner wire fixation save one anesthesia and surgery.

Biomechanical study on fixation methods for horizontal oblique metacarpal shaft fractures

OBJECTIVE

To investigate differences in the effectiveness of two lag screws, a regular bone plate, and locking bone plate fixation in treating horizontal oblique metacarpal shaft fractures.

MATERIALS AND METHODS

Horizontal oblique metacarpal shaft fractures were created in 21 artificial metacarpal bones and fixed using one of the three methods: (1) two lag screws, (2) a regular plate, and (3) a locking plate. All the specimens were subjected to the cantilever bending test performed using a material testing machine to enable recording of the force-displacement data of the specimens before failure. The Kruskal-Wallis test was used to compare failure force and stiffness values among the three fixation methods.

RESULTS

The mean failure force of the two lag screw group (78.5 ± 6.6 N, mean + SD) was higher than those of the regular plate group (69.3 ± 17.6 N) and locking plate group (68.2 ± 14.2 N). However, the mean failure force did not significantly differ among the three groups. The mean stiffness value of the two lag screw group (17.8 ± 2.6 N/mm) was lower than those of the regular plate group (20.2 ± 10.5 N/mm) and locking plate group (21.8 ± 3.8 N/mm). However, the mean stiffness value did not significantly differ among the three groups.

CONCLUSION

The fixation strength of two lag screw fixation did not significantly differ from that of regular and locking bone plate fixation, as indicated by the measurement of the ability to sustain force and stiffness.

Reinforcement strategy for medial open-wedge high tibial osteotomy: a finite element evaluation of the additional opposite screw technique and bone grafts

BACKGROUND AND OBJECTIVE

bone grafts (bgs) and the opposite screw insertion technique are reported to enhance initial stability after medial open-wedge high tibial osteotomy (OWHTO); however, it is unclear how the general and local biomechanical stability of the proximal tibia is affected by these reinforcement strategies. In this study, we aimed to assess the biomechanical differences among different fixation configurations for OWHTO under two loading conditions using finite element analysis, and to assess the biomechanical contribution of an opposite screw insertion.

METHODS

Models of the proximal tibia with three different gap defects were created to simulate different distraction heights in OWHTO. Four groups of models were then assembled with different fixation configurations, including the no BG (NBG) group, BG group, partially threaded screw (PT) group, and fully threaded screw (FT) group. Testing loads were applied to simulate the static forces on the knee joint during double-limb and single-limb standing. For each group, the stresses of the lateral hinge area (LHA) and the medial implant area (MIA), the maximum displacement of the tibia and the relative displacement (RD) of the medial gap were evaluated.

RESULTS

Compared to NBG group, bone block grafting effectively reduced the stress of the tibia and implant, as well as the maximum displacement of the tibia and the RD of the medial gap. The opposite screw group showed similar trends in alleviating the stress concentration on the LHA and MIA, and contributing to the maintaining the medial gap reduction, especially in the FT group; however, additional stresses were concentrated on the opposite screw itself, which indicated the potential risk of screw breakage.

CONCLUSIONS

Compared to NBG group, the BG group bone graft showed superior biomechanical advantages in decreasing the risk of implant failure and lateral hinge fracture, and maintaining the reduction in OWHTO. The additional opposite screw provided an extra support to the proximal tibia, with similar contributions to improve the structural stability after osteotomy, especially in the FT group.

No difference between lag screw and helical blade for cephalomedullary nail cut-out a systematic review and meta-analysis

INTRODUCTION

Cephalomedullary nail (CMN) cut-out is a severe complication of treatment of intertrochanteric femur fractures. This study aimed to identify modifiable risk factors predictive of implant cut-out including: CMN proximal fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, screw location, and surgeon fellowship training.

METHODS

A systematic review of the published literature was conducted on Pubmed/MEDLINE and Cochrane Library databases for English language papers (January 1st, 1985-May 10th, 2020), with 21 studies meeting inclusion/exclusion criteria. Studies providing quantitative data comparing factors affecting CMN nail cut-out were included, including fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, and screw location. Twelve studies were included and graded by MINOR and Newcastle-Ottawa Scale to identify potential biases. Meta-analysis and pooled analysis were conducted when possible with forest plots to summarize odds ratios (OR) and associated 95% confidence interval (CI).

RESULTS

There was no difference in implant cut-out rate between lag screws (n = 745) versus helical blade (n = 371) (OR: 1.03; 95% CI: 0.25-4.23). Pooled data analysis revealed TAD > 25 mm (n = 310) was associated with higher odds of increased cut-out rate relative to TAD < 25 mm (n = 730) (OR: 3.72; 95% CI: 2.06-6.72).

CONCLUSION

Our review suggests that cephalomedullary implant type (lag screw vs. helical blade) is not a risk factor for implant cut-out. Consistent with the previous literature, increased tip-apex distance > 25 mm is a reliable predictor of implant cut-out risk. Suboptimal screw location and poor reduction quality are associated with increased risk of screw cut-out.

LEVEL OF EVIDENCE

Level III.

Technical note on the removal of a "cold-welded" lag screw from a Trigen Meta-Tan nail

Intramedullary or cephalomedullary nail removal often is performed during nonunion reoperations. We have experienced a rare case in which it was difficult to remove the lag screw of the antegrade intramedullary nail, requiring a large amount of force to be applied over a long period. Removal of the lag screw is essential for removal of the nail and subsequent revision surgery. In our case, the lag screw could be removed only by cutting the screw with a carbide drill. For cases in which the nail and lag screw are firmly fixed, surgeons should prepare for the possibility of their separation using a carbide drill. Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Outcomes of Wedge Wing in the Lag Screw for Unstable Intertrochanteric Fractures in Elderly Patients

Purpose

To evaluate clinical-functional and radiologic outcomes of elderly patients with an unstable intertrochanteric femur fracture treated with a wedge wing in the lag screw.

Materials and Methods

Forty-eight patients treated with the Dyna Locking Trochanteric nail (DLT nail) to resolve an unstable intertrochanteric femur fracture were reviewed retrospectively. Based on AO/OTA classification, Fracture 31-A2 (34 cases) and 31-A3 (14 cases) were included in the analysis. We measured the femoral neck-shaft angle, tip-apex distance (TAD), Cleveland index, sliding distance of the lag screw, and time to the fracture union. The Harris Hip Score and Paker and Palmer's mobility score for clinical evaluation were used.

Results

The mean follow-up period was 21.4 months (range, 12–34 months). The postoperative state of reduction was good in 28 cases and acceptable in 20 cases. The mean TAD was 20.5 mm. The position of the lag screw was center-center in 30 cases and center-inferior in 18 cases. The mean sliding distance of the lag screw was 3.4 mm at the last follow-up. The mean union time was 4.5 months. Two cases had complications which included a cut-out (1 case) and non-union (1 case). The mean Harris Hip Score was 86.5±8.3 (range, 76–90). Walking ability in 34 of the cases (70.8%) at last follow-up was similar to that prior to fracture.

Conclusion

Functional and radiological outcomes are satisfactory using the DLT nail in the treatment of elderly patients with unstable intertrochanteric fractures; however, wedge wing in the lag screw does not prevent implant-related complications.

Anterior Odontoid Screw Fixation for C2 Fractures: Surgical Nuances, Complications, and Factors Affecting Fracture Union

OBJECTIVE

Type II odontoid fractures are the commonest C2 fractures. The management of dens fractures remains controversial with various radiological and fracture morphological factors affecting the approach and outcomes.

METHODS

All cases of anterior odontoid screw fixation between 2010 and 2020 were retrospectively analyzed. Patients' clinical, radiological (type of fracture, orientation, displacement, and diastasis), operative (single vs. double screw) and follow-up records were documented. The postoperative imaging findings were classified into grades I (excellent), II (good), and III (poor) based on the anatomical alignment with the screw. Follow-up cervical computed tomography was reviewed for fracture union.

RESULTS

A total of 49 patients with a mean age of 37.3 ± 13.8 years were included in the study. The average time from injury to surgery was 23.1 ± 22.2 days. The bicortical screw purchase and superoposterior odontoid tip breach significantly affected the postoperative alignment (P = 0.035 each). Fracture union was noted in 41 (83.7%) patients. The horizontal fracture displacement ≥2.5 mm (P = 0.02) and poor postoperative fracture alignment (P < 0.001) resulted in worse fracture union rates. Transient dysphagia was the commonest complication (n = 12), whereas screw breakout (n = 2) and pullout (n = 2) were other hardware-related complications. One patient underwent re-exploration for screw readjustment and 2 underwent posterior instrumentation.

CONCLUSIONS

Anterior odontoid screw fixation is technically straightforward, less morbid, and preserves biomechanical cervical mobility, when compared with the posterior instrumentation. With careful patient selection, meticulous surgical planning, and intraoperative image-guided screw insertion, good fracture union outcomes can be obtained. In the current study, we were able to achieve stable fracture union in 83.7% patients.

Lag screw with DHS (LSD) for vertical angle femoral neck fractures in young adults

Vertical Pauwels Type III fractures of the neck of femur in young patients are difficult fractures to treat. These are usually as a result of high energy trauma which are associated with a significant degree of fracture comminution in the neck of femur. This makes the fracture reduction and fixation difficult. Many fixation methods and implants have been described for use in these fractures but are not without reported complications such as non-union and varus collapse. In this article, we highlight the incidence of fracture comminution in both the anterior and posterior cortices of the femoral neck, better visualised with axial computed tomography scanning and describe a simple technique utilizing lag screws and a DHS implant to adequately address these fractures.

Outcomes of Patients Undergoing Anterior Screw Fixation for Odontoid Fracture and Analysis of the Predictive Factors for Surgical Failure

Objective

Anterior odontoid screw fixation (AOSF) is a safe and effective treatment for type II and rostral type III odontoid fracture. This study aimed to report the outcomes of the AOSF surgery and evaluate the potential risk factors of surgical failure.

Methods

We enrolled 63 patients who underwent AOSF. Follow-up computed tomography was performed 6 months after the surgery and once a year thereafter to evaluate the union. Clinical data including the age, sex, presenting symptoms, cause of injury, fracture gaps, dislocation position, degree of displacement, screw direction angle, and time interval from injury to operation were collected.

Results

Successful fusion was achieved in 55 patients (87.3%) and surgical failure occurred in 8 patients (12.7%). Variables such as age, sex, dislocation position, degree of displacement, screw direction angle, and time interval from injury to operation were not significantly associated with the surgical failure. However, surgical failure was statistically significantly associated with the fracture gap. The overall mean fracture gap at the time of injury was 1.29 mm (range, 0–3.11 mm), and the incidence of surgical failure was 8.3 times higher when the fracture gap at the time of injury was > 2 mm (p=0.019).

Conclusion

When performing AOSF in patients with type II or rostral shallow type III odontoid fractures, the displacement of the odontoid fracture fragment should be appropriately reduced to the aligning position before screw insertion and downward reduction should be achieved by perforation of the apical cortex of the odontoid during screw fixation, even if the surgery is delayed.

Management of Subchondral Lucencies of the Medial Aspect of the Equine Antebrachiocarpal Joint

The objective of this study is to describe the management and outcomes of eight horses with subchondral lucencies (SCLs) of the medial aspect of the antebrachiocarpal (ABC) joint. The medical records and radiographs of the carpi of 8 horses with SCLs of the medial aspect of the ABC joint were reviewed. Follow-up clinical information was obtained for 6-60 months (the median duration of 14 months). Treatment was successful if radiographic healing was apparent or lameness was reduced or eliminated. Four horses had SCLs in the distomedial radius (DMR) and four in the proximal aspect of the radiocarpal bone (RCB). Lameness was present in all horses with DMR SCLs and in one horse with an RCB SCL. Treatments included restriction of exercise (n = 3), intra-articular administration of corticosteroids (n = 2), or placement of a screw across the SCL (n = 3). Exercise restriction alone was successful in three nonlame horses younger than one year with proximal RCB SCL and intra-articular corticosteroid administration in the ABC joint in two horses aged 2 years or younger with DMR SCLs. A yearling with a large proximal RCB SCL and two horses aged 5 years or older with DMR SCLs were successfully treated with screw placement across the SCL. Exercise restrictions and intra-articular administration of corticosteroids were successful in management of DMR SCLs in five horses. Placing a screw across the SCL of three horses resulted in resolution of lameness and substantial improvement of the radiographic appearance of the lesion in the RCB or DMR.

The impact of lag screw in the healing time of distal tibia fractures treated with minimally invasive plate osteosynthesis: A randomized clinical trial

BACKGROUND

In recent years, Minimally Invasive Plate Osteosynthesis (MIPO) has been gaining popularity in the treatment of distal tibia fractures, because it is a minimally invasive surgical procedure, thus it limits the soft-tissues damage. This prospective randomized study aims to assess the impact of lag screw in the healing time of distal tibia fractures treated with MIPO technique, in a six-month follow-up.

METHODS

Patients between 20 and 70 years of age with distal tibial fracture, type 43-A according to AO/OTA classification system were included. All the patients were randomized into two groups, to receive MIPO without lag screw (Group-A) or MIPO with percutaneous lag screw (Group-B). Patients were followed clinically and radiographically at 3, 6, 12 and 24 weeks postoperatively. The main outcome measure was the time needed to achieve the painless full weight-bearing (FWB) after surgery. Unpaired t-test after ANOVA (analysis of variance) was performed to assess AOFAS score differences between the 2 groups at each follow-up. Pearson correlation test also was performed. The tests were two-tailed with a confidence level of 5%.

RESULTS

42 patients (24 male and 18 female, mean age 49.54 years old, range 25-80) were recruited. A significant shorter mean time until painless FWB (p = 0.016) was observed in Group-B (11.22 ± 3.06 weeks) compared with Group-A (13.48 ± 2.42 weeks) (Table 2). The mean AOFAS score was comparable in patients treated with (Group-B) and without lag screw (Group-A) at all follow-ups.

CONCLUSIONS

This prospective randomized clinical study has shown that the use of lag screw in distal tibia fractures treated with MIPO technique speeds the fracture healing, thus shortening the time needed to achieve FWB.

Fully threaded sacroiliac lag screws have higher load to failure when compared to partially threaded screws: A biomechanical study

The purpose of this study is to compare biomechanical properties of fully and partially threaded iliosacral screws. We hypothesise that fully threaded screws will have a higher yield force, and less deformation than partially threaded screws following axial loading. Twenty sawbone blocks were uniformly divided to simulate vertical sacral fractures. Ten blocks were affixed with fully threaded iliosacral screws in an over-drilled, lag-by-technique fashion whilst the remaining ten were fixed with partially threaded lag-by-design screws. All screws measured 7.3-mm x 145 mm, and were inserted to a 70% of calculated maximal insertional torque, ensuring uniform screw placement throughout across models. Continuous axial loads were applied to 3 constructs of each type to failure to determine baseline characteristics. Five hundred loading cycles of 500 N at 1 Hz were applied to 4 constructs of each type, and then axially loaded to failure. Force displacement curves, elastic, and plastic deformation of each construct was recorded. Fully threaded constructs had a 428% higher yield force, 61% higher stiffness, 125% higher ultimate force, and 66% lower yield deformation (p < 0.05). The average plastic deformation for partially threaded constructs was 336% higher than fully threaded constructs (p = 0.071), the final elastic deflection was 10% higher (p = 0.248), and the average total movement was 21% higher (p = 0.107). We conclude from this biomechanical study that fully threaded, lag-by-technique iliosacral screws can withstand significantly higher axial loads to failure than partially threaded screws. In addition, fully threaded screws trended towards exhibiting a significantly lower plastic deformation following cyclical loading.

Benefits of opposite screw insertion technique in medial open-wedge high tibial osteotomy: A virtual biomechanical study

Background

Alignment correction of the lower limb by medial open-wedge high tibial osteotomy (HTO) is an efficient technique, but loss of correction and hardware failure can occur owing to inadequate fixation. A surgical technique using opposite screw insertion was previously applied for salvage of the lateral hinge fracture, but evidence for its utility as a protective strategy was unclear.

Methods

Finite element models were reconstructed using artificial bone models, commercial bone plate, and locking screws in the HTO model. The 6.5-mm cancellous or 6.5/8.0-mm pretensioned lag screw was virtually inserted from the opposite cortex to the medial tibial plateau. Testing loads were applied for simulating standing and initial sit-to-stand postures. The axial displacement of the posteromedial tibial plateau, which represents the loss of the posteromedial tibial plateau in clinical observation, and stresses on the bone plate, locking screws, and opposite screws were evaluated.

Results

Pretensioned lag screw insertion effectively reduced the loss of posteromedial reduction compared with the HTO model without opposite screw insertion [6.5-mm lag screw, by 50.8% (standing)/56.3% (sit-to-stand); 8.0-mm lag screws, by 51.9% (standing)/57.5% (sit-to-stand); normalised by the performance in the intact model]. The noncompressed opposite cancellous screw slightly reduced the stresses on the bone plate and screws, but did not contribute to the control of reduction loss at the posteromedial tibial plateau. Stresses on screws were lower than those on the corresponding bone plates, so the risk of screw breakage may be low.

Conclusion

The present study revealed that pretensioned opposite lag screw insertion is a simple and effective technique to improve the structural stability in medial open-wedge HTO. Further biomechanical and clinical verification will be required to enhance user confidence in this technique.

The translational potential of this article

The efficacy and advantages of additional opposite lag screw insertion in medial wedge high tibial osteotomy surgery have been described in this current study by a virtual biomechanical evaluation. Basing on this observation, it would worth further clinical trials for clarification and verification in reality.

Kyphectomy and interbody fixation using lag screws in a child with myelomeningocele kyphosis: a technical case report

A 5-year-old boy had a thoracolumbar-level MMC that had been repaired at the day after birth and kyphotic deformity got worse as he grew. He complained of discomfort about not being able to take a supine posture and decided to perform surgery for kyphosis. In our case, surgical correction is offered to stop the deformity progression, manage the associated pain, and finally to gain sitting and supine posture. We report the surgical procedure with 4 levels of en bloc kyphectomy and using the lag screws. Especially when lag screws are used, several complications including posterior instrumentation failure, hardware prominence and wound break down can be solved by removing the implants after bone fusion has been achieved.

Principle of Lag-Screw Fixation in Mandibular Trauma

Aims and Objectives:

The aim of the study is to assess the effectiveness of lag screw fixation in mandibular fractures with respect to parameters such as stability of the occlusion, functional stability, infection rates, neurosensory deficit, ease of technique, and maximum interincisal opening.

Materials and Methods:

Our study was carried out on 13 patients with mandibular fractures. Selected cases were treated with lag screw technique and 2.7 mm titanium screws were used. Postoperative complications such as wound dehiscence, infection, neurosensory disturbance, nonunion, malocclusion, postoperative mouth opening, and occlusal discrepancies were assessed.

Results:

All the patients were male, aged between 17 and 50 years. The cause of the injury was road traffic accidents in all, except for two assaults. Our study of 13 cases of fractured mandible included five symphyses, five parasymphyses, two angle, and one body fracture cases. Our observation with open reduction and rigid internal fixation with 1–2 lag screws revealed close approximation of fractured fragments in all the cases, except in three patients who had mild discrepancy of occlusion.

Conclusion:

Lag screw technique provides good interfragmentary compression and restoration of premorbid anatomic alignment of fracture fragments. In displaced mandibular fractures, especially in oblique fractures, the use of lag screw has proven to be ideal. The complications were found to be low. It was concluded that the lag screw provided excellent stability and occlusion.

A novel technique using a pedicle screw and bucking bar for the treatment of hangman's fracture

The treatment of hangman's fracture is controversial. If treated with a traditional surgical procedure, there will likely be many complications, such as kyphosis, pseudarthrosis and nonunion. Our present study aims to describe a bucking bar method with pedicle screw fixation to treat hangman's fracture. Thirty-two patients with an unstable hangman's fracture who underwent posterior C2-3 pedicle lag screw fixation surgery assisted by a bucking bar between May 2004 and Jan 2017 were evaluated. All the participating patients were successfully treated using this novel technique, and follow-up revealed anatomical fusion in 27 patients, incomplete fusion in 4 patients, and C2-3 angular deformity healing in 1 patient. No patient developed throat wall edema or pseudomembrane formation. Satisfactory reduction, fixation and fusion of C2 pedicle fractures can be achieved using a pedicle screw assisted with the transoral bucking bar technique. LEVEL OF EVIDENCE: IV, retrospective case-series study.

Individual Surgical Strategy Using Posterior Lag Screw-Rod Technique for Unstable Atypical Hangman's Fracture Based on Different Fracture Patterns

OBJECTIVE

The literature on surgical management of atypical hangman's fracture (AHF) is sparse. The aim of this study was to describe an individual surgical strategy using a lag screw-rod technique for treatment of unstable AHF based on different fracture patterns.

METHODS

A retrospective analysis of 23 patients with unstable AHF was performed. Fractures were classified into 3 patterns: A, 1 fracture line through 1 side of C2 body obliquely and another through pars interarticularis on the other side; B, 1 fracture line through 1 side of C2 body obliquely and another through contralateral lamina; C, bilateral oblique fracture lines through posterior cortex of C2 on different sides. Posterior C2-C3 pedicle screw fixation and fusion using a lag screw-rod technique with different surgical strategies for each fracture pattern was used for all patients. Complications, neck pain, neurologic status, reduction of anterior translation and angulation between C2 and C3, and fusion rate were evaluated.

RESULTS

No technique-related complications (e.g., spinal cord or nerve injury caused by malposition of screws) occurred. Mean follow-up time was 37 months. Satisfactory reduction and bony union were demonstrated on postoperative radiographs. Neck pain and neurologic deficits caused by C2 injury improved significantly in all patients after operation. No graft or implant-related complications were observed in patients during the entire follow-up period.

CONCLUSIONS

Using individual surgical strategies based on different fracture patterns, the posterior C2-C3 lag screw-rod technique may be an effective and reliable option for unstable AHF.

Analysis of Computed Tomography Scan After Anterior Odontoid Screw Fixation with the Herbert Screw: Is It Effective to Reduce Fracture Gap?

OBJECTIVE

To assess computed tomography scans to evaluate the extent of reduction of fracture displacement and fracture gap after anterior odontoid screw fixation using the Herbert screw.

METHODS

Thirty-seven odontoid fractures were reduced and treated by anterior odontoid screw fixation with the Herbert screw. There were 37 patients whose age ranged from 20 to 79 years. Three-dimensional computed tomography scans were obtained for all patients to assess the screw position, the presence of the penetration of superior cortex of dens, the extent of reduction of fracture displacement, and fracture gap.

RESULTS

Mean fracture displacement was 2.6 ± 3.2 mm before surgery; after the operation this value was 1.0 ± 1.5 mm. The difference in fracture gap between the preoperative and the postoperative state was -0.1 ± 1.1 mm, which was not statistically significant (P = 0.667). We achieved cortical purchase in only 16 of 37 patients (43.2%); cortical purchase was not obtained in 21 patients (56.7%) due to the fear of the risk of the damage of neural and vascular structures. Of these 21 patients who had no penetration of the superior cortex of dens, widening of the fracture gap occurred in 12 patients (57%), no change in 6 patients (29%), and there was shortening in 3 patients (14%). However, of the 16 patients with penetration of apical dens tip, we achieved significant reduction of fracture gap (P = 0.002).

CONCLUSIONS

To maximize reduction of fracture gap using the Herbert screw, it is essential to penetrate the apical dens tip.

Failure of a Rotation Control Gamma 3 Lag Screw Used to Treat a Trochanteric Fracture

Gamma 3 rotation control lag screws (U-blade) are particularly useful when treating rotational and unstable fractures of the proximal femur. A 93-year-old woman who underwent closed reduction of a trochanteric fracture and internal fixation with a Gamma 3 nail rotation control lag screw. The patient presented with metal failure and U-blade bending following a fall occurring 4 weeks after surgery. Here, we present a case report summarizing removal of the failed lag screw.

Distal fibula oblique fracture fixation using one-third tubular plate with and without lag screw - A biomechanical study of stability

This laboratory-based study compared distal fibula simple oblique fracture fixation with one-third tubular plate with and without a single lag screw to determine which was mechanically more stable. A control group fixed with a limited contact dynamic compression plate was also tested. Biomechanical testing of 30 osteotomised saw bones under lateral bending and torsional forces was performed. There was no significant difference between the mean lateral bending and mean torsional stiffness between the fixation with tubular plate and lag screw and tubular plate alone. Limited contact dynamic compression plate conferred the best stability in lateral bending and torsion, as expected.

A novel technique for the fixation of inter-trochantieric hip fractures: A telescoping lag screw

One-hundred and three patients with intertrochanteric hip fractures as classified by the OTA 2007 system underwent fixation using the telescoping AOS Galileo lag screw system and ES Nail (a long IM nail). Thirty-one patients (76%) were female and ten (24%) were male, with an average age of 75.70 ± 11.3 years at date of surgery. At final follow-up 21 (53%) patients returned to their pre-fracture ambulatory status, 20 (47%) had a reduction in ambulatory status, and no patients were confined to a wheel chair. The telescoping capability of the AOS Galileo lag screw allowed for a decrease in total length by 3.96 ± 3.04 mm during fracture healing. The TAD distance at final follow-up was 14.09 ± 4.69 mm. Lateral protrusion of the lag screw into soft tissue did not occur. There was one reported incidence of femoral head cutout, which occurred after the lag screw had telescoped its entire distance and began functioning as a rigid non-compressible lag screw. All other fractures healed uneventfully and no device failure occurred. The AOS Galileo telescoping lag screw has shown promise concerning IT fracture fixation and will continue to undergo further investigation.

Does lag screw fixation of condylar fractures result in adequate stability? A finite element analysis

The great incidence and controversies related to the diagnosis, treatment, surgical accesses, and type of osteosynthesis materials confer an outstanding role to condylar fractures among facial fractures. Plate configurations, with diverse formats and sizes, may be used to surgically resolve condylar fractures. With the purpose of improving the advantages and minimizing the disadvantages of fixation techniques, the neck screw was developed aiming at the needed stabilization to render a correct fixation through a system of dynamic compression. This is achieved by increasing the contact between the fractured bone stumps, as well as assisting at the time of fracture reduction. The present paper aims at comparing the fixation and stability of mandibular condylar fractures using the neck screw and an overlaid "L"-shaped-4-hole-2 mm plate on the one hand, with a system in which the neck screw and the "L"-shaped plate form a single structure, having been joined by a welded point, on the other hand. The results with the neck screw are satisfactory, and, thus, it is an alternative for the reduction and fixation of fractures of the mandibular condyle, whether or not a plate is joined to the structure, provided it is correctly prescribed and with adequate surgical sequence and technique.

A practical 'safe zone' technique for lag screw fixation of the fibula

Introduction During ankle fracture fixation, iatrogenic trauma to retro fibula structures can result in morbidity and reoperation. We describe a safe zone for lag screw insertion. Materials and methods This study was completed in three sections. We identified the average entry and exit points for the lag screw using 45 Weber B ankle fractures identified from our trauma database. We then analysed 26 sequentially presented ankle magnetic resonance images, concentrating on axial sections at 4, 8, 12 and 16 mm above the ankle joint. Finally, we used 63 sequentially performed magnetic resonance scans to confirm the safe zone from these consistent structures. Results The typical lag screw exit point was 14.2 mm above the ankle joint (95% confidence Interval 11.3-17.1 mm). A safe zone trajectory occurred between 31 and 45 degrees taken from the anterior aspect of the flat fibular surface at this level. The obvious palpable landmark to direct screw trajectory and avoid 'at risk' structures was found to be the medial edge of the Achilles tendon. Our final dataset confirmed in 63 scans, the medial aspect of the Achilles tendon to be a consistent safe zone with a minimum distance of at risk structures of 4 mm. Conclusion This simple method of directing the fibula lag screw towards the palpable medial edge of the Achilles tendon is practical, easy to teach and directs the screw on a safe trajectory away from the most commonly injured structures around the back of the fibula.

A clinical prospective randomized comparative study on ostyeosynthesis of mandibular anterior fractures following open reduction using lag screws and miniplates

Introduction

The aim of the present study was to compare fixation of mandibular anterior fractures following open reduction using lag screws or miniplates.

Materials and Methods

This prospective study was conducted on 20 patients diagnosed with cases of displaced mandibular anterior fractures treated with open reduction and internal fixation. The patients were then randomly allocated to either of two groups - Group A: two 2.5 mm stainless steel lag screws were placed in 10 patients. Group B: two 2.5 mm miniplates were placed in 10 patients for the fixation of fractures. Subsequent follow-up was done on the 1^st day, 1^st, 4^th, and 36^th week postoperatively. During every follow-up, patient was assessed clinically for infection, malocclusion, loosening of plate/screw, malunion/nonunion, and masticatory efficiency. Radiographs (orthopantogram) were taken preoperative, 1^st, 4^th, and 36^th postoperative week to compare the osteosynthesis between the two groups. Pain was objectively measured using a visual analog scale. The data collected was subjected to unpaired t-test and paired t-test for statistical analysis.

Result

It was found that lag screw placement was rapid in comparison of miniplate placement. 3rd month postoperative assessment revealed Lag screw group to have better biting efficiency, and better bone healing which was statistically significant when compared with miniplate group.

Conculsion

Our study suggests that lag screw osteosynthesis can be advocated as a valid treatment modality in the management of mandibular symphysis and parasymphysis fractures.

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

INTRODUCTION

Lag 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.

METHODS

Between 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.

RESULTS

50 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 14.1mm±3.2 and in the control group was 14.9mm±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 45.8min±9.8 compared to 38.4min±9.3 in the control group (p=0.009).

CONCLUSIONS

Computer-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.

Tibial impingement secondary to distal fibular lag screw placement: A case report

Impingement, tibial erosions, and "painful hardware" caused by a lag screw used for malleolar fracture stabilization are rare occurrences. We report a case of a symptomatic lag screw, used to fix a distal fibular fracture, that impinged on the distal tibial and causing symptoms. Awareness of the condition and early diagnosis based on thoughtful review of CT images are key to symptom alleviation. A review of the published data on the complication of "painful hardware" following ankle fracture fixation is also presented.

A comparative study between traditional fixation with miniplates and modified lag screws for the treatment of mandibular fractures

OBJECTIVES

The objective of this study is to investigate two internal fixation surgical techniques for mandibular fractures in order to compare modified lag screw techniques with standard miniplates.

MATERIALS AND METHODS

This is an observational prospective study. Three hundred eighteen patients were operated on for mandibular fractures. The patients were divided into two groups according to the type of surgical technique used: modified lag screws (155 patients) and traditional miniplates (163 patients). Analyses were made of sociodemographic and preoperative variables, the parameters related to the fracture type and postoperative data.

RESULTS

There were no differences between the two groups regarding their sociodemographic characteristics. The modified lag screws were primarily used with double fractures, while conventional miniplates were more often used with simple fractures. The number of complications was higher with the miniplate technique. The unfavorable fractures had an OR of 5.75 due to postoperative complications; double fractures had an OR of 8.87 and simple fractures an OR of 19.53, which, in both cases, were lower with conventional miniplates than with modified lag screws.

CONCLUSION

Modified lag screws provide a rigid fixation system that is as secure as miniplates, but with greater compression between the fragments, less postsurgical gap, faster ossification, and fewer postoperative complications.

CLINICAL RELEVANCE

The modified screw technique is a safe tool that does not require any specific osteosynthesis materials not found in a basic traumatology kit and has a lower cost, due to the reduced amount of material used.

Unilateral C1 Sagittal Split Fractures: An Unusual Entity Revisited

BACKGROUND

An isolated, unilateral fracture of the C1 lateral mass is a rare condition that has been only minimally described in the literature. Historically, these fractures have predominantly been managed conservatively with either external immobilization or traction.

CASE DESCRIPTION

We review the literature and present 2 patients that presented after failing conservative management, but demonstrated excellent clinical outcomes after surgical treatment.

CONCLUSIONS

After failure of conservative management, unilateral sagittal split fractures may be safely and effectively managed with unilateral open reduction and placement of a lag screw.

Breakage of the Tail Portion of the Lag Screw during Removal of Proximal Femoral Zimmer Natural Nail: Report of Two Cases with Technical Notes

Proximal femoral cephalomedullary nailing is one of the treatments of choice for intertrochanteric fracture. Zimmer Natural Nail® (ZNN; Zimmer) is one of the alternatives. We report two cases of broken tail portion of the ZNN lag screw during the removal procedure. This may be the first reported cases in scientific literature with this pattern of failure. We report these cases to highlight one of the possible problems that could occur during removal of this implant which can possibly prolong the operation time significantly if the required device is not prepared.

Biomechanical Comparison of Inter-fragmentary Compression Pressures: Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

OBJECTIVE

The purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw.

METHODS

We compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws.

RESULTS

The mean compression pressures of the 40- and 45-mm long cannulated lag screws were 50.48±1.20 N and 53.88±1.02 N, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was 52.82±2.17 N, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure (60.68±2.03 N) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively).

CONCLUSION

Our results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

Absolute or relative stability in minimal invasive plate osteosynthesis of simple distal meta or diaphyseal tibia fractures?

INTRODUCTION

Minimal invasive plate osteosynthesis in simple distal meta or diaphyseal tibia fractures can be applied using absolute (lag screw and neutralisation plate; LSN) or relative stability (bridge plate; BP). The primary aim of the study was to compare time to radiological union and time to full weight bearing in the two groups (LSN vs. BP). Reduction was performed either percutaneously or by a minimally open approach (mini open). Secondary aim was to analyse the number of complications between both groups.

METHODS

Retrospective single centre review of patients with a simple distal meta or diaphyseal tibia fracture operated with a Locking Compression Plate (LCP) between 2009 and 2015 in a Level one Trauma Centre. Postoperative radiographs were assessed in a standardised manner. Time to radiological fracture union and time to full weight bearing were observed. Callus index and postoperative complications were analysed.

RESULTS

Fifty-seven patients with a minimum follow-up of 6 months were analysed. Forty-eight patients had a shaft (AO/OTA Type 42) and nine a distal tibia fracture (AO/OTA Type 43). Forty patients were treated with using the LSN concept and 17 patients with the BP concept. Median time to radiological fracture union was statistically significant shorter (p=0.04) in the LSN group with 19 weeks compared to 27 weeks in the BP-group. Time to full weight bearing was 10 weeks in both groups. A total (including implant removal) of 35 reoperations were performed in the LSN-group and 18 in the BP-group. Wound healing disorders (deep surgical site infections) were seen less the LSN group in 3/40 (7.5%) compared to the BP-group with 3/17 (17.6%). In the LSN group, there was no statistical difference in time to union or weight bearing between a percutaneous or mini open approach.

CONCLUSION

Stable osteosynthesis of simple distal meta or diaphyseal tibia fractures leads to faster radiologic fracture healing without an increase in complications or number of revisions compared to bridge plating. If a percutaneous reduction is not feasible for the insertion of a lag screw, a mini-open approach does not lead to a delay in fracture healing.

Wing-augmentation reduces femoral head cutting out of dynamic hip screw

The dynamic hip screw (DHS) is commonly used in the treatment of femoral intertrochanteric fracture with high satisfactory results. However, post-operative failure does occur and result in poor prognosis. The most common failure is femoral head varus collapse, followed by lag screw cut-out through the femoral head. In this study, a novel-designed DHS with two supplemental horizontal blades was used to improve the fixation stability. In this study, nine convention DHS and 9 Orthopaedic Device Research Center (ODRC) DHSs were tested in this study. Each implant was fixed into cellular polyurethane rigid foam as a surrogate of osteoporotic femoral head. Under biaxial rocking motion, all constructs were loaded to failure point (12mm axial displacement) or up to 20,000 cycles of 1.45kN peak magnitude were achieved, whichever occurred first. The migration kinematics was continuously monitored and recorded. The final tip-to-apex distance, rotational angle and varus deformation were also recorded. The results showed that the ODRC DHS sustained significantly more loading cycles and exhibited less axial migration in comparison to the conventional DHS. The ODRC DHS showed a significantly smaller bending strain and larger torsional strain compared to the conventional DHS. The changes in tip-to-apex distance (TAD), post-study varus angle, post-study rotational angle of the ODRC DHS were all significantly less than that of the conventional DHS (p < 0.05). We concluded that the ODRC DHS augmented with two horizontal wings would increase the bone-implant interface contact surface, dissipate the load to the screw itself, which improves the migration resistance and increases the anti-rotational implant effect. In conclusion, the proposed ODRC DHS demonstrated significantly better migration resistance and anti-rotational effect in comparison to the conventional DHS construct.

Removal of a broken trigen intertan intertrochanteric antegrade nail

Implant breakage is a serious complication after cephalomedullary nailing for unstable intertrochanteric fracture. Failure usually occurs at the lag screw hole in the nail body. On the other hand, lag screw failure is extremely rare and occurs around the nail-lag screw junction. We experienced rare mechanical failure of the Intertan nail, which showed breakage at the lag screw hole and failure of the integrated compression screw underneath the main lag screw.

Interfragmentary lag screw fixation in locking plate constructs increases stiffness in simple fracture patterns

BACKGROUND

The aim of the current biomechanical cadaver study was to quantify the influence of an additional lag screw on construct stiffness in simple fracture models at the distal femur stabilised with a locking plate.

METHODS

For biomechanical testing paired fresh frozen human femora of 5 donors (mean age: 71 (SD 9) years) were chosen. Different locking plate configurations either with or without interfragmentary lag screw were tested under torsional load (2/4Nm/deg) or axial compression forces (500/1000N).

FINDINGS

Data show that plate constructs with interfragmentary lag screw reveal similar axial and torsional stiffness values compared to intact bone as opposed to bridging plate constructs that showed significantly lower stiffness for both loading conditions.

INTERPRETATION

The current biomechanical testing unveils that the insertion of a lag screw combined with a locking plate dominates over a bridging plate construct at the distal femur in terms of axial and torsional stiffness.

Breakage of a Lag Screw of Cephalomedullary Nail: A Technique of Removal

A broken lag screw of the cephalomedullary nail is a rare condition. Removal of the retained lag screw from the femoral head is also very challenging. This article describes a surgical technique and the modified instrument that was available in the operating room for removing the broken implant by closed technique.

Does the IOFIX improve compression in ankle fusion?

BACKGROUND

The new IOFIX is an intra-osseous fixation device comprising an "X-post" through which a lag screw passes to apparently improve force distribution across an arthrodesis. We conducted a novel human cadaveric study. Our null hypothesis was no difference in force exists in an ankle arthrodesis model stabilized with the IOFIX or a conventional single lag screw.

METHOD

In ten cadaver ankles a pressure transducer was compressed as an IOFIX and standard single lag screws were alternately compared.

RESULTS

The median average force created by the IOFIX was 3.95kg and 2.4kg for the single conventional lag screw (p⩽0.01). The IOFIX improved contact area across the arthrodesis with a median average of 3.41cm(2) compared with 2.42cm(2) in the lag screw group (p⩽0.03).

CONCLUSION

Our results suggest an IOFIX improves force distribution across an ankle arthrodesis compared with a single conventional lag screw.

Retrograde lag screw placement in anterior acetabular column with regard to the anterior pelvic plane and midsagittal plane -- virtual mapping of 260 three-dimensional hemipelvises for quantitative anatomic analysis

Percutaneous screw placement can be used for minimally invasive treatment of none or minimally displaced fractures of the anterior column. The complex pelvic geometry can pose a major challenge even for experienced surgeons. The present study examined the preformed bone stock of the anterior column in 260 hemipelvises (130 male and 130 female). Screws were virtually implanted using iPlan(®) CMF (BrainLAB AG, Feldkirchen, Germany); the maximal implant length and the maximal implant diameter were assessed. The study showed, that 6.5mm can generally be used in men; in women however individual planning is essential in regard to the maximal implant diameter since we found that in 15.4% of women, screws with a diameter less than 6.5mm were necessary. The virtual analysis of the preformed bone stock corridor of the anterior column showed two constrictions of crucial clinical importance. These can be found after 18% and 55% (men) respectively 16% and 55% (women) measured from the entry point along the axis of the implant. The entry point of the retrograde anterior column screw in our collective was located lateral of tuberculum pubicum at the level of the superior-medial margin of foramen obturatum. In female patients, the entry point was located significantly more lateral of symphysis and closer to the cranial margin of ramus superior ossis pubis. The mean angle between the screw trajectory and the anterior pelvic plane in sagittal section was 31.6 ± 5.5°, the mean angle between the screw trajectory and the midsagittal plane in axial section was 55.9 ± 4.6° and the mean angle between the screw trajectory and the midsagittal plane in coronal section was 42.1 ± 3.9° with no significant deviation between both sexes. The individual angles formed by the screw trajectory and the anterior pelvic and midsagittal plane are independent from anthropometric parameters sex, age, body length and weight. Therefore, they can be used for orientation in lag screw placement keeping in mind that the entry point differs in both sexes.

Minimal invasive para-rectus approach for limited open reduction and percutaneous fixation of displaced acetabular fractures

INTRODUCTION

Minimal invasive fixation has been reported as an alternative option for treatment of acetabular fractures to avoid blood loss and complications of extensive approaches. Closed reduction and percutaneous lag screw fixation can be done in minimally displaced acetabular fractures. Open reduction is indicated, if there is wide displacement. In this study, we report the use of a mini-open anterior approach to manipulate and reduce anteriorly displaced transverse acetabular fractures combined with percutaneous lag screw fixation.

METHODS

This report included eight patients. All had anterior displaced simple transverse acetabular fractures. An oblique mini-incision was made above and medial to the mid-inguinal point, and lateral to the lateral border of rectus abdominis muscle. The external abdominal oblique aponeurosis was incised along its fibres. The arched fibres of internal abdominal oblique were displaced medially above the inguinal ligament to expose and incise the fascia transversalis. Care was taken to avoid injury of ilioinguinal nerve, inferior epigastric vessels, and spermatic cord. The external iliac vessels were palpated and protected laterally. A blunt long bone impactor was introduced through this small incision to manipulate and reduce the fracture under fluoroscopic control. Fluoroscopic guided percutaneous lag screw fixation was done in all patients.

RESULTS

The average time to operation was 4 days. Average blood loss was 110mL. Operative time averaged 95min. Maximum fracture displacement averaged 10mm preoperatively and 1.3mm postoperatively. According to Matta score, anatomical reduction of the fracture was achieved in five patients and imperfect in three. Follow up averaged 27 months. Wound healing occurred without complications and fracture union was achieved without secondary displacement in all patients. Average time to fracture healing was 14 weeks. According to the modified Merle d'Aubigné score, functional outcome was good to excellent in all patients.

DISCUSSION AND CONCLUSION

Limited open reduction can solve the problem of fracture reduction, which is the main concern in minimal invasive fixation of acetabular fractures. It may help the inclusion of displaced acetabular fractures for percutaneous lag screw fixation. This mini-para-rectus approach has the advantages of minimal soft tissue dissection with the possible anatomical reduction of simple transverse displaced acetabular fractures.

Computed tomographic evaluation of the proximal femur: A predictive classification in displaced femoral neck fracture management

BACKGROUND

Femoral neck fracture is truly an enigma due to the high incidence of avascular necrosis and nonunion. Different methods have been described to determine the size of the femoral head fragment, as a small head has been said to be associated with poor outcome and nonunion due to inadequate implant purchase in the proximal fragment. These methods were two dimensional and were affected by radiography techniques, therefore did not determine true head size. Computed tomography (CT) is an important option to measure true head size as images can be obtained in three dimensions. Henceforth, we subjected patients to CT scan of hip in cases with displaced fracture neck of femur. The study aims to define the term small head or inadequate size femoral head" objectively for its prognostic significance.

MATERIALS AND METHODS

70 cases of displaced femoral neck fractures underwent CT scan preoperatively for proximal femoral geometric measurements of both hips. Dual energy X-ray absorptiometry scan was done in all cases. Patients were treated with either intertrochanteric osteotomy or lag screw osteosynthesis based on the size of the head fragment on plain radiographs.

RESULTS

The average femoral head fragment volume was 57 cu cm (range 28.3-84.91 cu cm; standard deviation 14 cu cm). Proximal fragment volume of >43 cu cm was termed adequate size (type I) and of ≤43 cu cm as small femoral head (type II). Fractures which united (n = 54) had a relatively large average head size (59 cu cm) when compared to fractures that did not (n = 16), which had a small average head size (49 cu cm) and this difference was statistically significant. In type I fractures union rate was comparable in both osteotomy and lag screw groups (P > 0.05). Lag screw fixation failed invariably, while osteotomy showed good results in type II fractures (P < 0.05).

CONCLUSION

Computed tomography scan of the proximal femur is advisable for measuring true size of head fragment. An objective classification based on the femoral head size (type I and type II) is proposed. Osteosynthesis should be the preferred method of treatment in type I and osteotomy or prosthetic replacement is the method of choice for type II femoral neck fractures.