Distal Interlocking Screws Research Articles

Risk factors for malalignment after intramedullary nail treatment of distal tibia fractures with associated fibula fractures

PurposeMalalignment of distal tibia fractures can lead to malunion/nonunion or alter the limb mechanical axis which may cause arthritis. Proposed methods to decrease malalignment include fibular fixation or multiplanar interlocking screws, however these remain controversial. This study aimed to identify factors associated with malalignment in distal tibial fractures with associated fibular shaft fractures.MethodsA retrospective review was performed of distal tibia fractures with associated fibular shaft fractures treated with intramedullary nailing at two level one trauma centers between 2015 and 2019. Cases involving malalignment (> 5° of deviation from anatomic axis on either coronal/sagittal axis) on final follow-up (minimum three months postoperatively) were compared to those without malalignment with regard to demographics, fracture characteristics, intraoperative characteristics, and complications.ResultsThe rate of malalignment was 13%. On multivariate analysis, multiplanar distal interlocking screw fixation (odds ratio [OR], 0.18; 95% confidence interval [CI] 0.03–0.92) was associated with a decreased rate of final malalignment, while nail diameter > 10 mm was associated with a higher rate (OR, 4.05; 95% CI 1.25–13.11). Fibular fixation was not associated with malalignment.ConclusionMultiplanar distal interlocking screws may protect against malalignment. Fibula fixation does not appear associated with a decreased rate of malalignment in distal tibia fractures treated with intramedullary nails.Level of EvidenceIII.

Early Complications of a Novel Retrograde Intramedullary Femoral Nail in the Treatment of Femur Fractures.

To determine the early implant failure rate of a novel retrograde intramedullary femoral nail. Retrospective cohort study. Academic level 1 trauma center. Patients aged 18 years and older with an acute OTA/AO 32-A, 32-B, 32-C, and 33-A fractures or periprosthetic distal femur fracture from April 2018 to April 2022 were included in the study. The 2 interventions compared were the Synthes Expert retrograde/antegrade femoral nail (or control implant) versus the next-generation retrograde femoral nail (RFN)-advanced retrograde femoral nail (RFNA or experimental implant) (Synthes, West Chester, PA). Early implant-related complications between the experimental and control implants were assessed including locking screw back out, screw breakage, intramedullary nail failure, need for secondary surgery, and loss of fracture reduction. Three hundred fourteen patients were identified with a mean age of 31.0 years, and 62.4% of the patients being male. Open fractures occurred in 32.5% of patients with 3.8% of injuries being distal femur periprosthetic fractures. Fifty-six patients were in the experimental group and 258 patients in the control group. Mean follow-up was 46.8 weeks for the control cohort and 21.0 weeks for the experimental cohort. Distal interlocking screw back out occurred in 23.2% (13 of 56) of the experimental group patients and 1.9% (5 of 258) of the control group patients ( P < 0.0001). Initial diagnosis of interlocking screw back out occurred at an average of 3.2 weeks postoperatively (range, 2-12 weeks). Fifty-four percent of patients who sustained screw back out underwent a secondary operation to remove the symptomatic screws (12.5% of all patients treated with the experimental implant required an unplanned secondary operation due to screw back out). A logistic regression model was used to predict screw back out and found the experimental implant group was 4.3 times as likely to experience distal locking screw back out compared with the control group ( P = 0.01). The retrograde femoral nail-advanced implant was associated with a significantly higher rate of screw back out with a substantial number of unplanned secondary surgeries compared with the previous generation of this implant. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Revision total hip arthroplasty using a modular fluted, tapered revision femoral component and interlocking screws in Vancouver B3 periprosthetic fractures with insufficient bone at the isthmus.

Revision total hip arthroplasty in patients with Vancouver type B3 fractures with Paprosky type IIIA, IIIB, and IV femoral defects are difficult to treat. One option for Paprovsky type IIIB and IV defects involves modular cementless, tapered, revision femoral components in conjunction with distal interlocking screws. The aim of this study was to analyze the rate of reoperations and complications and union of the fracture, subsidence of the stem, mortality, and the clinical outcomes in these patients. A total of 46 femoral components in patients with Vancouver B3 fractures (23 with Paprosky type IIIA, 19 with type IIIB, and four with type IV defects) in 46 patients were revised with a transfemoral approach using a modular, tapered, cementless revision Revitan curved femoral component with distal cone-in-cone fixation and prospectively followed for a mean of 48.8 months (SD 23.9; 24 to 112). The mean age of the patients was 80.4 years (66 to 100). Additional distal interlocking was also used in 23 fractures in which distal cone-in-cone fixation in the isthmus was < 3 cm. One patient (2.2%) died during the first postoperative year. After six months, 43 patients (93.5%) had osseous, and three had fibrous consolidation of the fracture and the bony flap, 42 (91.3%) had bony ingrowth and four had stable fibrous fixation of the stem. No patient had radiolucency around the interlocking screws and no screw broke. One patient had non-progressive subsidence and two had a dislocation. The mean Harris Hip Score increased from of 57.8 points (SD 7.9) three months postoperatively to 76.1 points (SD 10.7) 24 months postoperatively. The 2° tapered, fluted revision femoral component with distal cone-in-cone-fixation, combined with additional distal interlocking in patients with bony deficiency at the isthmus, led to reproducibly good results in patients with a Vancouver B3 fracture and Paprosky type IIIA, IIIB, and IV defects with regard to union of the fracture, subsidence or loosening of the stem, and clinical outcomes.

Research progress on distal interlocking screws of cephalomedullary nails in intertrochanteric fractures

To summarize the new research progress in distal interlocking screws of cephalomedullary nails for the treatment of intertrochanteric fractures. Relevant domestic and foreign literature was extensively reviewed to summarize the static/dynamic types of distal interlocking screw holes, biomechanical studies, clinical studies and application principles, effects on toggling in the cavity, and related complications of distal interlocking screws. The mode of the distal interlocking screw holes can be divided into static and dynamic. Distal interlocking screws play the role of anti-rotation, maintaining femur length, resisting compression stress, increasing torque stiffness, resisting varus stress, etc. The number of the screws directly affects the toggling of the main nail in the cavity. At present, regardless of whether long or short nails are used, distal interlocking screws are routinely inserted in clinical practice. However, using distal interlocking screws can significantly increase the duration of anesthesia and operation, increase fluoroscopy exposure time, surgical blood loss, and incision length. There is a trend of trying not to use distal interlocking screws in recent years. No significant difference is found in some studies between the effectiveness of dynamic and static interlocking for AO/Orthopaedic Trauma Association (AO/OTA) 31-A1/2 fractures. At present, the selection of the number and mode of distal interlocking screws is still controversial. When inserting distal interlocking screws, orthopedists should endeavor to minimize the occurrence of complications concerning miss shot, vascular injuries, local stress stimulation, and peri-implant fractures. Distal interlocking screws are mainly used to prevent rotation. For stable fractures with intact lateral walls, long cephalomedullary nails can be used without distal interlocking screws. For any type of intertrochanteric fractures, distal interlocking screws are required when using short cephalomedullary nails for fixation. Different interlocking modes, the number of interlocking screws, and the application prospects of absorbable interlocking screws may be future research directions.

Off target of distal interlocking screw in short cephalomedullary nail fixation for intertrochanteric femur fractures

To analyze the causes and treatment of off target of the distal interlocking screws when short cephalomeduallry nails were installed through jig-guided targeting device, and to put forward the technical points to prevent off target. Retrospective analysis of 9 patients with intertrochanteric fractures treated between July 2014 and June 2023 was conducted, in which off target occurred during the insertion of the distal interlocking screw by jig-guided targeting device in short cephalomedullary nailling (<24 cm). There were 1 male and 8 females, with an average age of 82.7 years (range, 73-94 years). There were 3 cases of type A1, 5 cases of type A2, and 1 case of type A3 according to 2018-AO/Orthopaedic Trauma Association (AO/OTA) fracture classification. As for the misaligned distal interlocking screw, six parameters were collected and analyzed, including the time of finding, the position, the type of passing through the cortical bone, the special circumstances during operation (such as the need to remove the intramedullary nail for reaming the diaphysis, hammering, etc.), the treatment, and the patient follow-up results. In the 9 patients, the off target of the distal interlocking screw was found in 7 cases during operation and in 2 cases after operation; the locking screw was located behind the nail in 7 cases and in front of the nail in 2 cases; the off target locking screw was passing tangentially in transcortical patern in 6 cases and in bicortical pattern through the medullary cavity in 3 cases. Three cases were attributed to the mismatch between the nail and the femur, two of which were attributed to the narrow femoral medullary cavity, one of which was attributed to the large anterolateral femoral bowing, and the other 6 cases were attributed to technical errors such as the loosening of the jig-guided targeting device, the tension of the fascia lata, and the blunt of the drill. In the 7 cases found during operation, the misaligned interlocking screw was removed first and the screw hole was left vacant, then in 2 cases, the interlocking screw was not used further; in 1 case, the distal dynamic hole was successfully inserted with a dynamic guide frame, and in 4 cases, the interlocking screw was successfully put after 2-3 attempts, leaving a large hole in the lateral cortex. No special treatment was performed in 2 cases found after operation. One patient was out of bed early after operation, 7 patients were in bed for 1 month, and 1 patient deteriorated to A3 type after operation and was in bed for 3 months. All the 9 patients were followed up 6-12 months, with an average of 8 months. Fracture healing was achieved in 8 patients. One patient with vacant interlocking screw had a secondary spiral fracture of the femoral shaft 3 months later, and was refixed with a long cephalomedullary nail and circlage wiring. Distal interlocking screw off target is rare, but when it occurs, it leaves a large cortical hole in the osteoporotic femoral shaft, reducing bone strength; the use of precision instruments and attention to technical details can reduce this adverse phenomenon.

Femur Fractures in 5 Individuals With Pantothenate Kinase-associated Neurodegeneration: The Role of Dystonia and Suggested Management.

Pantothenate kinase-associated neurodegeneration (PKAN) is a rare, neurodegenerative disorder that manifests with progressive loss of ambulation and refractory dystonia, especially in the early-onset classic form. This leads to osteopenia and stress on long bones, which pose an increased risk of atraumatic femur fractures. The purpose of this study is to describe the unique challenges in managing femur fractures in PKAN and the effect of disease manifestations on surgical outcomes. A retrospective case review was conducted on 5 patients (ages 10 to 20y) with PKAN with a femur fracture requiring surgical intervention. Data regarding initial presentation, surgical treatment, complications, and outcomes were obtained. All patients were non-ambulatory, with 4 of 5 patients sustaining an atraumatic femur fracture in the setting of dystonia episode. One patient had an additional contralateral acetabular fracture. Postoperatively, 4 of the 5 patients sustained orthopaedic complications requiring surgical revision, with 3 of these secondary to dystonia. Overall, 4 required prolonged hospitalization in the setting of refractory dystonia. Femur fractures in PKAN present distinct challenges for successful outcomes. A rigid intramedullary rod with proximal and distal interlocking screws is most protective against surgical complications associated with refractory dystonia occurring during the postoperative period. Multidisciplinary planning for postoperative care is essential and may include aggressive sedation and pain management to decrease the risk of subsequent injuries or complications. Level IV.

Backout of Distal Interlocking Screws After Retrograde Femoral Nailing With a Novel Device: A Case Series.

To report upon a series of patients who have experienced the backout of distal interlocking screws after retrograde femoral nailing with the DePuy Synthes RFN-Advanced Retrograde Femoral Nailing System (DePuy Synthes, Raynham, MA). Retrospective case series. Twenty-seven skeletally mature patients with femoral shaft or distal femur fractures who underwent operative fixation with the DePuy Synthes RFN-Advanced Retrograde Femoral Nailing System with 8 patients subsequently experiencing backout of distal interlocking screws. The study intervention included retrospective review of patient charts and radiographs. The incidence rate of distal interlocking screw backout. Thirty percent of patients experienced the backout of at least 1 distal interlocking screw (mean: 1.625) after undergoing retrograde femoral nailing with the RFN-Advanced system. Thirteen total screws backed out postoperatively. Screw backout was identified an average of 61 days postoperatively (range: 30-139 days). All patients complained of implant prominence and pain along the medial or lateral aspect of the knee. Five patients elected to return to the operating room to remove the symptomatic implant. The oblique distal interlocking screws comprised 62% of screw backouts. Given the high incidence rate of this complication, the associated costs of reoperation, and patient discomfort, we believe that a further investigation into this implant complication is warranted. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Decision Making in Combined Hip Arthroscopy and Femoral Derotational Osteotomy Surgeries

Background: Femoral version abnormalities can contribute to intra-articular hip pathology. Combined hip arthroscopy with femoral derotational osteotomy (FDRO) has been shown to successfully treat those with intra-articular hip pathology with excessive anteversion or retroversion of the femur. Indications: We describe the technique for combined hip arthroscopy and FDRO in patients with symptomatic intra-articular hip pathology in the setting of excessive anteversion or retroversion of the femur. Technique Description: Hip arthroscopy is performed using standard anterolateral, modified mid-anterior, and distal anterolateral accessory portals. The labrum is repaired using a narrow diameter suture. Femoroplasty is performed with utilization of fluoroscopic imaging to assess resection. Dynamic flexion is performed as a final check of adequacy of resection. Capsular closure is performed in all cases. After hip arthroscopy, the patient is repositioned on a radiolucent table. A piriformis start point is obtained with a guide pin followed by standard opening reaming and ball-tipped guidewire placement. A femoral osteotomy is made just proximal to the isthmus and made through a lateral approach to the femur. Two K-wires are placed distal and proximal to the osteotomy site. A goniometer is then used to measure rotation. A drill is used to perforate the cortex circumferentially at the osteotomy site. After standard reaming, a sagittal saw is then used to start the osteotomy cut followed by an osteotome. An intramedullary nail is inserted over a ball-tipped guidewire while rotational reduction is assessed from the foot of the operating table. Distal interlocking screws are placed, and the nail is backslapped to create compression at the osteotomy site prior to placing proximal interlocking screws. Results: Recent studies show improved hip outcome scores in patients who undergo concomitant hip arthroscopy and FDRO for symptomatic abnormal femoral version. Discussion/Conclusion: Identifying patients who would benefit from concomitant surgeries requires thorough preoperative evaluation. Correct identification and treatment of these patients leads to improved outcomes. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Effect of Implant Linkage on Axial and Rotational Stiffness of Nail-Plate Constructs for Comminuted Distal Femoral Fractures.

To determine the effect of linking the intramedullary nail and the laterally applied locking plate to treat comminuted distal femur fractures and allow for immediate weight bearing. Comminuted extra-articular distal femur fractures were created in 16 synthetic osteoporotic femurs and split into 2 groups: linked versus unlinked. In the linked construct, in addition to standard plate fixation and proximal locking of the nail, 2 nonthreaded locking bolts (prototypes) were placed through both the plate and the nail. In the unlinked construct, the same number of screws affixed the plate to the bone but were directed around the nail, and separate distal interlocking screws were placed for nail fixation. Each specimen underwent sequential axial and torsional loading, and axial and torsional stiffness were calculated and compared. On average, the unlinked constructs demonstrated a greater axial stiffness at all levels of axial loading, and linked constructs demonstrated greater average rotational stiffness. However, there were no statistically significant differences ( P > 0.189) between the linked and unlinked groups at any axial or torsional load. In distal femur fractures with metaphyseal comminution, there were no significant differences in axial or torsional stiffness when linking the plate to the nail. Linking the construct seems to provide no significant mechanical advantage compared with the unlinked environment, but it may be a useful strategy to reduce nail "traffic" in the distal segment with no significant disadvantage.

Technique for removing a “cold-welded” interlocking screw from an intramedullary nail in the femur: A case report

Rationale: Removing a bent or broken intramedullary (IM) nail can be challenging even if the nail is intact. Several methods have been described for removing bent or broken nails. However, few studies have reported the removal of an IM nail when a proximal interlocking screw is cold-welded. We hope to share our successful treatment strategy for future use. Patient concerns: A 33-year-old male was admitted to our clinic for IM nail removal. The patient complained of discomfort in his right thigh when the weather changed. He had fallen down the stairs 3 years prior, causing a closed fracture of the right femur, and was treated with an IM nail. Diagnoses: Radiography showed an IM nail in the right femur. Interventions: Initially, the distal interlocking screw was easily removed using a screwdriver. Attempts to remove the proximal interlocking screw using various methods were futile. Finally, a high-speed cutting burr was used to cut the proximal interlocking screw. Outcomes: The IM nail was successfully removed. Lessons: A cold-welded proximal interlocking screw was encountered during IM nail removal. The applied technique is an effective alternative when a screw is difficult to remove using conventional tools.

Observational prospective unblinded case-control study to evaluate the effect of the Gamma3® distal targeting system for long nails on radiation exposure and time for distal screw placement

PurposeTo determine if the DTS decreases radiation exposure (primary outcome measure), fluoroscopy time (secondary outcome measure), and time to distal screw placement (secondary outcome measure) compared to the freehand “perfect circles” method when used for locking of cephalomedullary nails in the treatment of femur fractures MethodsFifty-eight patients with hip or femoral shaft fractures that were treated with a long cephalomedullary nail were enrolled in this study. Cohorts were determined based on the method of distal interlocking screw placement into either the “Perfect Circles” or “Distal Targeting” cohort. Time from cephalad screw placement to placement of final distal interlocking screw (seconds), radiation exposure (mGy), and fluoroscopy time (seconds) were compared between groups. Hospital quality measures were compared between cohorts. ResultsUse of the DTS resulted in 77% (4.3x) lower radiation exposure (p < 0.001), 64% (2.7x) lower fluoroscopy time (p < 0.001), and 60% (1.7x) lower intraoperative time from end of cephalad screw placement to end of distal interlocking screw placement (p < 0.001) compared to the freehand “perfect circles” method. There was no difference in 30-day or 90-day complication rates between cohorts. ConclusionThe Stryker Gamma3® Distal Targeting System is a safe, effective and efficient alternative to the freehand “perfect circles” method.

Derotational Plate Augmentation with Retention of Intramedullary Interlocking Nail in Resistant Nonunion at Distal Femur Shaft

Background: Non-union in femur shaft after satisfactory treatment with closed intramedullary interlocking nail is not very common. This nonunion is always a challenging condition for surgeon. These nonunion are usually treated by dynamization, close exchange nail with larger diameter, retention of nail and onlay bone graft, removal of nail and fixed with plates and bone graft, removal of nail and application of cast brace and sometimes removal of nail and applications of external fixators. But no treatment is’ gold standard’ the rotational instability is blamed to be one of the most common reason of nonunion. Aim: To control rotational instability, we did plate augmentation with or without bone grafts without removing the nail to treat this nonunion. Methods: Total patients were 16. Proximal and distal interlocking screws were removed, nonunion site was opened, compression at nonunion site was done, and broad DCP was applied as de rotation plate with or without bone grating. We excluded fracture less than one-year duration and fracture with infective nonunion. Results: In 12 patients bone grafting was done where there was less callus or there was suspicion of atrophic non-union. We got union in all patients. 6.25 months were average time of union. 13 months was average time between the primary and secondary surgery. 71 minutes was means surgical time. Complications or implant failure were not noted. 0.9 cm was average residual limb shortening and 115 degrees was average range of motion at knee joint. Conclusion: Nonunion in distal femur shaft fracture with interlocking nail in situ is reliable and effective procedure Keywords: Distal femur, plate, External fixator. Bone grafting

Locking in trochanteric fractures: a comparison of static versus dynamic locking using the Gamma3 nail.

The Gamma3 nail (Stryker®) is an intramedullary device consisting of a proximal lag screw and distal interlocking screw. It is still unknown whether the screw locking mode could influence clinical outcomes. The aim of this study is to compare static and dynamic screw locking regarding their influence on surgical revisions and lag screw displacement. A retrospective single-centre study was performed on patients ≥ 60years admitted for a trochanteric fracture between September 2016 and January 2020. Surgical revisions and lag screw displacement were evaluated at6 weeks and 1-year follow-up, respectively. A total of 142 patients were included for analysis. Surgical revisions were needed in 13 cases (9.2%). Indications included implant breakage (n = 3), lag screw cut-out (n = 3), lateral hip pain (n = 6) and non-union (n = 1). The number of surgical revisions was not different between static and dynamic locking (OR 2.55; 95%CI 0.73-8.56; p 0.142). The median lag screw displacement was 2.5mm, which was similar for static and dynamic locking (2.3mm versus 2.7mm; p 0.785). The screw locking mode of the Gamma3 nail is not associated with a higher risk of surgical revisions. However, the design of the Gamma3 nail may not be suitable for static locking.

Acute Correction of Multiplanar Proximal Tibial Deformity Utilizing Fixator-Assisted Intramedullary Nailing.

The patient is positioned supine on a radiolucent table. The locations of the proximal tibial osteotomy, fibular osteotomy, external fixator pin sites, and intramedullary nail insertion site are marked with use of a surgical marker and fluoroscopic imaging. Large external fixator half-pins are placed proximal and distal to the planned tibial osteotomy in both the anterior-posterior and sagittal planes, avoiding the path of the planned tibial intramedullary nail. A fibular osteotomy and then a low-energy tibial osteotomy are performed with use of multiple drill holes and an osteotome. Next, the bone deformity is fully corrected and held in the corrected alignment with the external fixators. Then, the opening drill for the intramedullary nail is introduced into the proximal aspect of the tibia over a guidewire, and blocking screws are placed in the coronal and sagittal planes of the proximal fragment next to the opening reamer. The intramedullary canal is then reamed over a ball-tipped guidewire to the desired diameter and the selected intramedullary nail is placed and secured with proximal and distal interlocking screws. Finally, the external fixators are removed. Alternative operative treatments include external fixation and gradual or acute deformity correction as well as fixator-assisted acute deformity correction and plate fixation13-16. Typically, a tibial osteotomy with gradual deformity correction with use of a circular fixator is employed for the treatment of these deformities3,17. The literature shows this to be an effective technique for accurate correction of these complex proximal tibial deformities. With the advent of internal motorized lengthening nails, however, there have been increasing efforts to develop safe and accurate techniques for acutely correcting bone deformity so that these nails can be utilized to treat both angular deformities and bone-length differences simultaneously. Deformity at the proximal aspect of the tibia is often multiplanar, and complete correction of these deformities requires translation, angulation, and rotation through the osteotomy. An osteotomy performed at the proximal aspect of the tibia results in the equivalent of a proximal-third tibial fracture, which is more challenging and more demanding to fix than a diaphyseal tibial fracture because of the wide medullary canal and the strong deforming muscular forces at the proximal tibia. Fixator-assisted intramedullary nailing with blocking screws allows for the accurate correction of the mechanical and anatomic axes while avoiding external fixation. The expected outcome is complete bone deformity correction and healing of the osteotomy site(s)2. Careful preoperative planning is essential to accurately correct the anatomic and mechanical axes in all planes.In cases of acute correction of severe bone deformities, consider prophylactic nerve decompression.When possible, avoid the use of a tourniquet in order to minimize tissue trauma, postoperative swelling, and the need for prophylactic fasciotomies.Obtain and hold perfect osseous alignment with use of temporary uniplanar external fixators prior to placing any definitive hardware. AP = anteroposteriorIM = intramedullaryPACS = picture archiving and communication systemK-wire = Kirschner wireCORA = center of rotation and angulationDVT = deep venous thrombosisPE = pulmonary embolism.

Use of a locking stem for reverse shoulder arthroplasty is a rare but reliable option.

RSA is widely used in the treatment of complex trauma or degenerative changes of the shoulder. Strong primary fixation of the stem is necessary to prevent any loosening of the stem and subsequent revision. Presently, cement fixation or press-fit fixation are two options for humeral fixation, though each has its own limitations and risks. The aim of the current study is to evaluate the effectiveness of an alternative option involving a distal screw interlocking system for fixation of the humeral stem from initial implantation. We performed a retrospective multicenter study of patients implanted with the Humelock Reversed® stem RSA that can be locked with distal humeral screws in cases of operative poor press fit or to modulate the lengthening of the arm via prosthetic humeral height. Seventy-two patients with a minimum two year follow-up were included, 13 for acute trauma, 42 for degenerative changes, and 17 for revision surgery. No difference was seen in radiological or clinical results for patients with or without interlocking screw primary stabilization. For non-trauma patients, the mean raw Constant score improved significantly from 31 (± 12) to 71 (± 12). For trauma patients, the mean raw Constant score for trauma (63.4) was significantly lower than for non-trauma cases (72.1) (p < 0.001). Analysis of the filling ratio demonstrated that interlocking screws were not used for lower filling ratios and that midterm fixation of the stem is not negatively impacted by distal interlocking screw fixation. Even if use of a distal interlocking screw fixation system is rare, it can be useful for patients with poor quality fixation of stemmed RSA. Use of an interlocking screw system to stabilize the stem in RSA provides good immediate and midterm stability of the implant allowing for clinical and radiological outcomes comparable to those obtained with press-fit fixation alone.

Comparision of Distal Uniplanar Locking with Biplanar Distal Locking in Intramedullary Interlocking Nailing of Fractures Distal Shaft of Tibia

Objective: To study the effects of distal uniplanar locking and distal bi planar locking on union times in uncomplicated fractures distal shaft of tibia managed with an intramedullary interlocking nail.&#x0D; Study Design: Comparative prospective study.&#x0D; Place and Duration of Study: Department of Orthopedics and Trauma Combined Military Hospital Rawalpindi from Jan to Nov 2020.&#x0D; Methodology: Fifty-three patients having fractures distal shaft of tibia managed with intramedullary interlocking nail were studied. Twenty-nine patients were managed using two interlocking screws distally (uniplanar) in coronal plane (group-1). Twenty-four patients were managed with three bi planar screws comprising two coronal and one sagittal distal interlocking screw (group-2). Patients were followed every 4 weeks, and bone union time was assessed. Isolated closed fractures treated with closed reduction were included.&#x0D; Results: Patients treated with distal bi planar locking (group-2) had significantly reduced union time in weeks (11.25 ± 1.42) compared to uniplanar distal interlocking (group-1) (15.79 ± 1.80) (p&lt;.001).&#x0D; Conclusion: Union time for distal tibia shaft fractures is significantly reduced when treated with distal biplanar locking; it can be attributed to increased stability of the construct.

Comparative study of intertrochanteric fracture fixation using proximal femoral nail with and without distal interlocking screws.

BACKGROUNDIntertrochanteric (IT) fracture is one of the most common fractures seen in an orthopaedic practice. Proximal femoral nailing (PFN) is a common modality of fixing IT femur fracture. We retrospectively studied whether a PFN with two proximal lag screws can be done without distal interlocking screws in the 31-A1 and 31-A2 fracture patterns according to the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) guidelines for IT femur fractures.AIMTo compare the outcomes of IT fractures (AO/OTA 31-A1 and 31-A2) treated by PFN with and without distal interlocking screws.METHODSWe carried out a retrospective study of 140 patients in a tertiary care centre who had AO/OTA type 31-A1 and 31-A2 IT fractures. We divided the patients into two groups, in which one of the groups received distal interlocking screws (group 1) and the other group did not (group 2). The subjects were followed up for a mean period of 14 mo and assessed for radiological union time, fracture site collapse, mechanical stability of implant, and complications associated with the PFN with distal interlocking and without distal interlocking. Then, the results were compared.RESULTSPFN without distal interlocking screws has several advantages and gives better results over PFN with distal interlocking screws in the AO/OTA 31-A2 fracture pattern. However, similar results were observed in both groups with the fracture pattern AO/OTA 31-A1. In patients with fracture pattern AO/OTA 31-A2 treated by PFN without distal interlocking screws, there were minimal proximal lock-related complications and no risk of distal interlock-related complications. The operative time, IITV radiation time and time to radiological union were reduced. These patients also had better rotational alignment of the proximal femur, and the anatomy of the proximal femur was well maintained. It was also noted that in the cases where distal interlocking was performed, there was a gradual decrease in neck shaft angle, which led to varus collapse and failure of bone-implant construct in 21.40%.CONCLUSIONIn fracture pattern AO/OTA 31-A2, PFN without distal interlocking had better results and less complications than PFN with distal interlocking.

Short cephalomedullary nail toggle: a closer examination.

Objectives:In patients with wide femoral canals, an undersized short nail may not provide adequate stability, leading to toggling of the nail around the distal interlocking screw and subsequent loss of reduction. The purpose of this study was to identify risk factors associated with nail toggle and to examine whether increased nail toggle is associated with increased varus collapse.Design:Retrospective cohort study.Setting:Level 1 and level 3 trauma center.Patients/Participants:Seventy-one patients with intertrochanteric femur fractures treated with short cephalomedullary nails (CMN) from October 2013 to December 2017.Intervention:Short CMN.Main Outcome Measurements:Nail toggle and varus collapse were measured on intraoperative and final follow-up radiographs. Risk factors for nail toggle including demographics, fracture classification, quality of reduction, Dorr type, nail/canal diameter ratio, lag screw engaging the lateral cortex, and tip-apex distance (TAD) were recorded.Results:On multivariate regression analysis, shorter TAD (P = .005) and smaller nail/canal ratio (P < .001) were associated with increased nail toggle. Seven patients (10%) sustained nail toggle >4 degrees. They had a smaller nail/canal ratio (0.54 vs 0.74, P < .001), more commonly Dorr C (57% vs 14%, P = .025), lower incidence of lag screw engaging the lateral cortex (29% vs 73%, P = .026), shorter TAD (13.4 mm vs 18.5 mm, P = .042), and greater varus collapse (6.2 degrees vs 1.3 degrees, P < .001) compared to patients with nail toggle < 4 degrees.Conclusions:Lower percentage nail fill of the canal and shorter TAD are risk factors for increased nail toggle in short CMNs. Increased nail toggle is associated with increased varus collapse. Level of evidence: Therapeutic Level III

Effect of Intramedullary Nailing Patterns on Interfragmentary Strain in a Mouse Femur Fracture: A Parametric Finite Element Analysis.

Delayed long bone fracture healing and nonunion continue to be a significant socioeconomic burden. While mechanical stimulation is known to be an important determinant of the bone repair process, understanding how the magnitude, mode, and commencement of interfragmentary strain (IFS) affect fracture healing can guide new therapeutic strategies to prevent delayed healing or nonunion. Mouse models provide a means to investigate the molecular and cellular aspects of fracture repair, yet there is only one commercially available, clinically-relevant, locking intramedullary nail (IMN) currently available for studying long bone fractures in rodents. Having access to alternative IMNs would allow a variety of mechanical environments at the fracture site to be evaluated, and the purpose of this proof-of-concept finite element analysis study is to identify which IMN design parameters have the largest impact on IFS in a murine transverse femoral osteotomy model. Using the dimensions of the clinically relevant IMN as a guide, the nail material, distance between interlocking screws, and clearance between the nail and endosteal surface were varied between simulations. Of these parameters, changing the nail material from stainless steel (SS) to polyetheretherketone (PEEK) had the largest impact on IFS. Reducing the distance between the proximal and distal interlocking screws substantially affected IFS only when nail modulus was low. Therefore, IMNs with low modulus (e.g., PEEK) can be used alongside commercially available SS nails to investigate the effect of initial IFS or stability on fracture healing with respect to different biological conditions of repair in rodents.

A Novel Distal Interlocking Screw Guidance System Using a Laser Pointer and a Mechanical Fine-Adjustment Device

In minimally invasive bone fracture reduction surgery, broken femur bones are firmly fixed to a metallic intramedullary nail (IMN) after they are properly aligned. One of the greatest challenges of this process is that surgeons cannot directly see holes on the IMN, which increases the difficulty of the procedure and results in the requirement of taking a large number of X-ray images to find the location and direction of holes. We propose a novel distal interlocking screw guidance system that consists of a parallel guidance system using a laser pointer (PGSLP) and a mechanical fine-adjustment device (FAD). The PGSLP is used to make the planes of the C-arm and FAD parallel. The FAD is used to concentrically align the IMN hole with the guiding hole. The performance of the proposed device was evaluated by a series of experiments. The tilted angle error between the C-arm and FAD was measured to be 1.24 ± 0.715°. The translational error between the IMN hole and guiding hole was measured to be 0.378 ± 0.120 mm. Since the proposed guiding system is simple, cost-effective, and accurate, we expect it will soon be used in real operations.