Hybrid Fixation Technique Research Articles

Hybrid Fixation for Large Unstable Juvenile Osteochondritis Dissecans Lesions: Midterm Results in Adolescent Patients With Completely or Partially Salvageable Progeny Fragment.

This study aimed to describe the midterm clinical and radiographic outcomes of a hybrid fixation technique (HFT) combining interfragmentary compression with screws and biological support provided by the osteochondral autograft transplantation system (OATS) for treating large unstable juvenile osteochondritis dissecans (JOCD) lesions involving the knee in patients aged ≤18 years. Thirteen patients (15 knees, 9 males) with unstable JOCD lesions in the knee underwent treatment. HFT was indicated for lesions that had a completely salvageable (N=10) or partially salvageable progeny fragment (N=5). Patients were evaluated at a minimum follow-up of 1 year. The mean age of the patients was 15.3 years (range, 11 to 18y), with 10 lesions involving the medial femoral condyle and 5 involving the lateral femoral condyle. The mean lesion area were 397.7mm2. The outcome measures included the Pedi-IKDC and Tegner activity scales. Radiographic evaluation consisted of assessing osteochondral graft integration using the MOCART score on MRI and determining the degree of osteoarthritis using the Kellgren-Lawrence system (KL). At a mean follow-up of 51 months (range, 12 to 143mo), the mean Pedi-IKDC and Tegner activity scale were 90.1±7.2 and 94.7±6.7 points, respectively. Patients with unilateral lesions resumed sports activities on average after 7.7 months (range, 6 to 12mo). All patients exhibited progeny fragment integration on MRI, with a mean MOCART score of 85±6.5 (range, 75 to 95). Radiographs indicated grade 1 KL joint space in 13 knees and grade 2 in 2 knees. At the last follow-up, 12 patients were asymptomatic, whereas 1 patient experienced occasional mild discomfort during intense physical activity. Six patients required additional surgery for hardware removal, and 1 patient underwent intra-articular loose body removal. The hybrid fixation technique showed promising outcomes in terms of fragment healing and midterm results for unstable JOCD lesions. These findings suggest that HFT can be considered a valid treatment option for large unstable lesions involving the femoral condyles of the knee in adolescents. Therapeutic study (level of evidence IV).

Superior accuracy in knee double level osteotomy using a novel hybrid fixation technique compared to conventional double plating.

This study aimed to compare two different double-level knee osteotomy (DLO) fixation techniques. The primary outcome reported the radiological coronal plane correction and its accuracy. The secondary outcomes reported the correction outliers, the clinical outcomes, the 5-year postoperative satisfaction and the complications. A retrospective review of a single surgeon osteotomy database identified 52 cases of DLO between 2011 and 2019, of which 24 cases met the inclusion criteria. Patients were categorised into two groups: the nail-plate (NP) group fixed with a magnetic extendable intramedullary tibial nail and femoral conventional plate, and the double-plate (DP) group fixed with conventional plates (tibia and femur). Radiographic parameters were recorded, including the mechanical femorotibial angle (mFTA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle (mLDFA), joint line convergence angle (JLCA) and weight-bearing line ratio (Mikulicz %). Surgical accuracy was calculated as the difference between the achieved and the planned correction. Outliers were defined as those with a greater than 10% difference from the planned correction. Simple knee value scores and visual analogue scale for pain were recorded preoperatively and postoperatively at 2 and 5 years. Five-year patient satisfaction was recorded. A total of 24 patients were included: the NP group (n = 12) and the DP group (n = 12). Significant coronal plane corrections were achieved in the NP group for the mean mFTA (preoperative 167.9° ± 3.4° to postoperative 182.1° ± 1.4°), the mean MPTA (preoperative 83.5° ± 2.9° to postoperative 91.3° ± 2.8°) and the mean mLDFA (preoperative 89.8° ± 3.4° to postoperative 85.9° ± 4.4°). Similarly, significant coronal plane corrections were achieved in the DP group for the mean mFTA (preoperative 168.6° ± 4.4° to postoperative 182.2° ± 2°), the mean MPTA (preoperative 84.2° ± 2° to postoperative 88.3° ± 4.1°) and the mean mLDFA (preoperative 90.7° ± 2.9° to postoperative 83.9° ± 1.7°) (all p < 0.05). The mean correction accuracy was higher for the NP versus DP group at 3.4 ± 3.4% versus 7.1 ± 3.9% (intergroup p < 0.05). There were no outliers in the NP group versus two outliers (overcorrected) (16.7%) in the DP group. Significant clinical improvement was reported in both groups at 2 and 5 years postoperatively (all p < 0.05). Superior correction accuracy and no outliers were achieved in hybrid fixation double-level knee osteotomy compared to the conventional double-plating technique. The magnetic extendable nail offers the advantage of fine-tuning the correction postoperatively and could be a potential research template for future designs of postoperative correction implants. Level III, retrospective cohort study.

A systematic review and meta-analysis of hybrid vs. cemented stems - which method is more optimal for revision total knee arthroplasty?

The number of primary and revision Total Knee Arthroplasty (TKA) cases are expected to increase in future. There are various advantages and disadvantage to employing either of the two main types of stem fixation methods - cemented or hybrid technique. This review aimed to study the most optimal fixation method for revision TKAs by comparing radiological outcomes and re-revision rates. A systematic review and meta-analysis was performed using PubMed and Cochrane Library from 2010 to identify studies explicitly comparing outcomes between cemented against hybrid fixation revision TKA techniques, with a minimum follow up of at least 24 months. A total of 8 studies was included in this review. Egger's test and visual inspection of the funnel plot did not reveal publication bias. There was no statistically significant difference in radiological failure and loosening (OR 0.79, CI 0.37-1.66, I2 = 29%, p = 0.22), all causes of re-revision (OR 1.03, CI 0.73-1.44, I2 = 0%, p = 0.56) and aseptic revision (OR 0.74, CI 0.27-2.02, I2 = 0%, p = 0.41) between cemented and hybrid techniques. Functional and pain outcomes compared between the two fixation techniques were largely similar across the studies included in this meta-analysis. Despite a trend favouring hybrid stems in revision TKA, current evidence revealed that radiological outcomes and re-revision rates are largely similar between cemented and hybrid fixation techniques.

FUNCTIONAL OUTCOME OF TOTAL HIP ARTHROPLASTY WITH DUAL MOBILITY CUPS IN HIP ARTHRITIS-A PROSPECTIVE COHORT STUDY

Background: Dual mobility (DM) total hip arthroplasty (THA) has gained popularity due to its potential to enhance stability and reduce dislocation rates compared to traditional THA constructs. However, there is a need for further investigation into its functional outcomes, complications, and implant survivorship. Method: We conducted a hospital-based prospective study involving 50 patients undergoing total hip replacement over a one-year period. Functional outcomes were assessed using the Harris Hip Score (HHS) and Posterior Muscle Endurance (PME) Score. Descriptive statistics were used for data analysis. Results: The study population consisted predominantly of older patients (mean age 64.30 years), with a higher representation of males (56%). The most common diagnosis was neck of femur fracture (NOF#) (75%), with a balanced distribution of cemented (40%), uncemented (40%), and hybrid (20%) fixation techniques. HHS and PME scores showed significant improvements over 12 months, with excellent outcomes observed in 61.1% of participants. Complications occurred in 14% of patients, with peri-prosthetic fracture and surgical site infection being the most common. Implant survivorship at final follow-up was 94%. Conclusion: Dual mobility cup total hip replacement demonstrates promising outcomes in terms of functional improvement, low complication rates, and high implant survivorship. It represents a viable option for patients undergoing THA, particularly those at risk of dislocation. Further research, including prospective comparative studies, is needed to better understand its long-term efficacy and suitability across different patient populations.

Unilateral Biplanar Screw-Rod Fixation Technique for the Treatment of Odontoid Fractures in Patients with Atlantoaxial Bone or Vascular Abnormalities

This study aims to introduce the Unilateral Biplanar Screw-Rod Fixation (UBSF) technique (A hybrid fixation technique: Two sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures. Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and CT scans were conducted and reviewed at 1 day, and patients asked return for CT reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index pre-surgery and at one week and 12 months post-surgery. Between January 2016 to December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck VAS and NDI scores improved significantly at 1 week and 12 months postoperative (P < 0.01). The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation.

Hybrid cortical bone trajectory and modified cortical bone trajectory techniques in transforaminal lumbar interbody fusion at L4-L5 segment: A finite element analysis

BackgroundThe academia has increasingly acknowledged the superior biomechanical performance of the hybrid fixation technique in recent years. However, there is a lack of research on the hybrid fixation technique using BCS (Bilateral Cortical Screws) and BMCS (Bilateral Modified Cortical Screws). This study aims to investigate the biomechanical performance of the BCS and BMCS hybrid fixation technique in transforaminal lumbar interbody fusion (TLIF) at the L4-L5 segment in a complete lumbar-sacral finite element model. MethodsThree cadaver specimens are used to construct three lumbar-sacral finite element models. The biomechanical properties of various fixation technologies (BCS-BCS, BMCS-BMCS, BMCS-BCS, and BCS-BMCS) are evaluated at the L4-5 segment with a TLIF procedure conducted, including the range of motion (ROM) of the L4-5 segment, as well as the stress experienced by the cage, screws, and rods. The testing is conducted under specific loading conditions, including a compressive load of 400 N and a torque of 7.5Nm, subjecting the model to simulate flexion, extension, lateral bending, and rotation. ResultsNo significant variations are seen in the ROM at the L4-5 segment when comparing the four fixation procedures during flexion and extension. However, when it comes to lateral bending and rotation, the ROM is ordered in descending order as BCS-BCS, BCS-BMCS, BMCS-BMCS, and BMCS-BCS. The maximum stress experienced by the cage is observed to be highest within the BMCS-BCS technique during movements including flexion, extension, and lateral bending. Conversely, the BMCS-BMCS technique exhibits the highest cage stress levels during rotational movements. The stress applies to the screws and rods order the sequence of BCS-BCS, BCS-BMCS, BMCS-BCS, and BMCS-BMCS throughout all four working conditions. ConclusionThe BMCS-BCS technique shows better biomechanical performance with less ROM and lower stress on the internal fixation system compared to other fixation techniques. BMCS-BMCS technology has similar mechanical performance to BMCS-BCS but has more contact area between screws and cortical bone, making it better for patients with severe osteoporosis.

Strains on the human femur after revision total knee arthroplasty: An in vitro study using digital image correlation.

Pain at the tip of the stem of a knee prosthesis (End-of-Stem Pain) is a common problem in revision total knee arthroplasty (TKA). It may be caused by a problematic interaction between stem and bone, but the exact biomechanical correlate is still unknown. On top of this, there is no biomechanical study investigating End-of-Stem Pain at the distal femur using human specimens. Aim of this study was to find out whether the implantation of a revision total knee implant leads to high femoral surface strains at the tip of the stem, which the authors expect to be the biomechanical correlate of End-of-Stem Pain. We implanted 16 rotating hinge knee implants into 16 fresh-frozen human femora using the hybrid fixation technique and comparing two reaming protocols. Afterwards, surface strains on these femora were measured under dynamic load in two different load scenarios (climbing stairs and chair rising) using digital image correlation (DIC) and fracture patterns after overcritical load were analysed. Peak surface strains were found at the tip of the stem in several measurements in both load scenarios. There were no significant differences between the two compared groups (different trial sizes) regarding surface strains and fracture patterns. We conclude that implantation of a long intramedullary stem in revision TKA can lead to high surface strains at the tip of the stem that may be the correlate of femoral End-of-Stem Pain. This finding might allow for a targeted development of future stem designs that can lead to lower surface strains and therefore might reduce End-of-Stem Pain. Digital Image Correlation proved valid for the measurement of surface strains and can be used in the future to test new stem designs in vitro.

Incidence of postoperative complications in patellar fractures related to different methods of osteosynthesis procedures - a retrospective cohort study

BackgroundPatellar fractures have a comparatively low incidence compared to all fracture frequencies of the musculoskeletal system. However, surgical management is crucial to prevent postoperative complications that affect the knee joint. The purpose of the present study was to evaluate the incidence of postoperative complications and onset of postoperative osteoarthritis related to the chosen technique of patellar fracture management.MethodsIn a retrospective cohort study consecutive managed, isolated patella fractures were reviewed for demographic data, trauma mechanism, patella fracture type, fixation technique and postoperative complications. The results were documented radiographically and clinically and analysed statistically. The reporting followed the STROBE guidelines.ResultsA total of 112 patients were eligible for data evaluation. Surgical management of comminuted patellar fractures with small fragment screws showed significant fewer postoperative complications compared to other fixation techniques (8%, p < 0.043). The incidence of posttraumatic infection was significantly higher following the hybrid fixation technique with cannulated screws and tension wire than following the other analysed techniques (p = 0.024). No postoperative wound infection was observed after screw fixation or locking plate fixation. Symptomatic hardware was most frequently seen after tension-band fixation. Onset of posttraumatic osteoarthritis was most often found after the hybrid fixation technique (55%).ConclusionSurgical management of patellar fractures remains crucial but fracture fixation using plating systems or small fragment screws is least associated with postoperative complications.Trial registrationTrial registration number (DRKS):00027894.

The effect of different hybrid rigid internal fixation techniques on the postoperative stability following a mandibular advancement using a bilateral sagittal split ramus osteotomy: A retrospective three-dimensional comparative study

ObjectiveTo three-dimensionally evaluate post-operative mandibular stability following bilateral sagittal split ramus osteotomies between hybrid and non-hybrid rigid internal fixation techniques. Materials and MethodSeventy adults with skeletal class II deformity who underwent bilateral split sagittal osteotomy with mandibular advancement were included. Patients were divided into four groups based on their fixation techniques: hybrid technique (HT) groups I, II, and IV received a 4-hole 2 mm miniplate with either a bicortical screw (BS), additional 2 mm 4-hole miniplate, or two-hole miniplate, while non-HT group III received a 4-hole 2 mm miniplate with four mini-screws (MS). Measurements were taken pre-operatively (T0), immediately postoperatively (T1), and ≥1 year after surgery (T2) using 3D Slicer software. ResultsAge, sex, and follow-up period did not correlate significantly with postoperative relapse or stability. Significant differences were observed in the advancement on the right side between groups II, III, and IV and on the left side between groups I, III, and IV. However, the type of surgical intervention showed no significant effect on postoperative relapse and stability. All groups of fixations showed satisfactory stability with irrelevant relapse (< 2 mm or 2°). ConclusionThe study demonstrated satisfactory and comparable stability among different fixation groups on patients undergoing mandibular advancement following bilateral split sagittal osteotomy. The results highlighted the importance of considering the degree of advancement when planning orthognathic surgery and managing postoperative outcomes.

Comparison of four surgical methods for pediatric forearm double diaphyseal fractures: a retrospective analysis.

One of the most frequent fractures in children is a double forearm fracture. They make up 26% of children's long bone fractures in the upper extremities and their incidence has increased in recent years. In this study, pediatric patients with double forearm fractures were treated using plate screw, intramedullary K-wire (I-KW), intramedullary titanium elastic nails (TENs), and hybrid fixation (HF) to compare the radiographic and functional results. The printed and digital medical records were retrospectively examined from our hospital's archives after receiving consent from the regional ethics committee. Legal guardians of the patients, who were under the age of 18, gave their informed consent. Based on the surgical procedure used, the patients were split into 4 groups. Double plating was the D-P group, hybrid fixation method was the HF group, intramedullary elastic titanium nail was the TEN group, and intramedullary K-wire was the I-KW group. The study comprised 78 patients in total, with 19 patients in the HF group, 21 patients in the TEN group, 20 patients in the I-KW group, and 18 patients in the D-P group. When the mean operating times of the four approaches were compared, a substantial difference was found. The D-P group's mean operating time (65.2±4.9 minutes) was noticeably longer than those of the other groups (p<0.001). The HF group's mean operating time was 55.93.4 min longer than that of the TENs and I-KW groups, which was statistically significant (p<0.001). In comparison to the other groups, the D-P group's mean intraoperative fluoroscopy time was considerably shorter (6±3 sec) (p<0.001). When compared to the D-P group, it was considerably higher in the HF group (12±2 sec) (p<0.001). In comparison to the TENs (20±4 sec) and I-KW groups (19±5 sec), it was significantly lower in the HF group (p<0.001). In comparison to the HF group, the D-P group's tourniquet use lasted much longer (p<0.001). The TENs and I-KW groups did not use a tourniquet because a mini-incision was made. The D-P group's mean blood loss (110±10 ml) was substantially larger than that of the other groups (p<0.001) in the mean blood loss data. In comparison to the TENs (40±5 ml) and I-KW (40±5 ml) groups, the mean blood loss in the HF group (90±10 ml) was considerably larger (p<0.001). All patients received an above-elbow postoperative cast. The HF group (2 weeks) and the D-P group (2 weeks) experienced significantly less postoperative immobility than the TENs and I-KW groups (4.4 weeks, p<0.001). The four fixation techniques used in the current study for juvenile diaphyseal double forearm fractures produced positive clinical and functional outcomes. The hybrid fixation technique was discovered to be comparable to the other techniques and even beneficial in some ways. So, a safe and efficient treatment option for juvenile diaphyseal double forearm fractures is hybrid fixation.

Hybrid pedicle screw and modified cortical bone trajectory technique in transforaminal lumbar interbody fusion at L4-L5 segment: finite element analysis

BackgroundInvestigate the biomechanical properties of the hybrid fixation technique with bilateral pedicle screw (BPS) and bilateral modified cortical bone trajectory screw (BMCS) in L4-L5 transforaminal lumbar interbody fusion (TLIF).Methods Three finite element (FE) models of the L1-S1 lumbar spine were established according to the three human cadaveric lumbar specimens. BPS-BMCS (BPS at L4 and BMCS at L5), BMCS-BPS (BMCS at L4 and BPS at L5), BPS-BPS (BPS at L4 and L5), and BMCS-BMCS (BMCS at L4 and L5) were implanted into the L4-L5 segment of each FE model. The range of motion (ROM) of the L4-L5 segment, von Mises stress of the fixation, intervertebral cage, and rod were compared under a 400-N compressive load with 7.5 Nm moments in flexion, extension, bending, and rotation.Results BPS-BMCS technique has the lowest ROM in extension and rotation, and BMCS-BMCS technique has the lowest ROM in flexion and lateral bending. The BMCS-BMCS technique showed maximal cage stress in flexion and lateral bending, and the BPS-BPS technique in extension and rotation. Compared to the BPS-BPS and BMCS-BMCS technique, BPS-BMCS technique presented a lower risk of screw breakage and BMCS-BPS technique presented a lower risk of rod breakage.Conclusion The results of this study support that the use of the BPS-BMCS and BMCS-BPS techniques in TLIF surgery for offering the superior stability and a lower risk of cage subsidence and instrument-related complication.

High Survivorship of Hybrid Fixation Technique in Aseptic Condylar Revision Total Knee Arthroplasty with Minimal Metaphyseal Bone Loss: 5-10 Year Clinical Outcomes.

The aim of this study was to evaluate the outcomes of hybrid fixation technique in aseptic condylar revision total knee arthroplasty (rTKA). A retrospective consecutive study of patients with minimal metaphyseal bone loss who underwent aseptic rTKA with press-fit cementless femoral stems and short cemented tibial stems. Primary outcome measure was mechanical failure. Surgical complications, reoperations and revision for any cause were collected and Knee society score at final follow-up. Kaplan-Meier survival curves were used to estimate implant survivorship. Seventy-three patients were included with minimum 5 years follow-up with a mean age of 74.5 years. At mean follow-up of 8.5 years (range 5-10), only two patients required revision, both for infection. Radiographic evaluation was undertaken for all remaining patients at final follow-up and showed no evidence of mechanical failure. Six patients (8.4%) showed non-progressive radiolucent lines around the cementless femoral stem with only one having a pedestal at the tip of the femoral stem and four patients (5.6%) showed non-progressive radiolucent lines around the cemented tibial stem. Mean KSS score was 80.6 (standard deviation 13.8) indicating satisfactory clinical outcomes. Using "any cause implant revision" as an end point, implant survivorship for this construct was 97.3% at mean 8.5 years. In our experience, a hybrid fixation technique with a press-fit cementless femoral stem and a short-cemented tibial stemmed construct achieves excellent medium- to long-term outcomes in aseptic condylar revision cases with minimal metaphyseal bone loss.

Hybrid Fixation of Failed Internally Fixed Distal Femoral Fracture with an Extramedullary Locking Plate and an Intramedullary Cortical Strut Allograft Construct- A Case Report

Abstract Introduction: Fractures in osteoporotic bones present a surgical challenge for fixation and are often associated with significant morbidity. Case presentation: We present a case of failed internal fixation of fracture femoral shaft in a 74-year-old patient with osteoporosis. Fracture fixation was undertaken using an extra medullary locking plate and an intramedullary cortical strut graft, a hybrid fixation technique, a Locking Plate Allograft Construct. Discussion: Bone grafts are often used to support the native bone. By using a hybrid technique, the locking plate allograft construct achieves an enhanced stability of fracture fixation compared to plate alone, thus improving the outcome of surgery in osteoporotic bone fractures. Conclusion: Hybrid fixation using locking plate allograft constructs are relatively easy to perform and provide superior fixation to routine methods in osteoporotic bone fractures.

Hybrid fixation of unicompartmental knee arthroplasty shows equivalent short-term implant survivorship and clinical scores compared to standard fixation techniques.

There is a paucity of data regarding hybrid-fixated unicompartmental knee arthroplasty (UKA), and no study directly compared all three available fixation techniques (cementless, cemented, and hybrid). The hypothesis was that hybrid fixation might have a lower incidence of radiolucent lines (RLL) than cemented UKA, with equivalent outcomes to uncemented UKA. A total of 104 UKA with a minimal follow-up of 1 year were retrospectively included, of which 40 were cemented, 41 cementless, and 23 hybrid prostheses. The functional outcomes scores included the Oxford Knee (OKS), Subjective Knee (SKS), and Forgotten Joint scores (FJS). RLLs, subsidence, and component positioning were assessed on radiographs. At a mean follow-up of 28months, the survival rate was 95% for cemented UKA and 100% for the cementless and hybrid UKA (n.s.), respectively. Postoperative FJS (93 vs. 82 points, p = 0.007) and SKS (4.7 vs. 4.1 points, p = 0.001) were better in cementless than cemented UKA, with hybrid-fixated UKA in between the two (90 and 4.4 points, n.s.). Improvement of OKS preoperatively to postoperatively did not differ between the groups (n.s.). RLLs were more frequent in cemented (23%) compared to cementless (5%, p = 0.021) and hybrid UKA (9%, n.s.). With an incidence of 12%, subsidence occurred more commonly in cementless UKA compared to cemented (5%) and hybrid (0%) (n.s.) UKA. Hybrid fixation achieves equivalent results to standard UKA fixation techniques regarding implant survival and functional and radiological outcomes. Therefore, the hybrid fixation technique seems to be a valuable alternative as it combines the advantages of cemented tibial components with those of uncemented femoral components. III.

Biomechanical Effects of Stemmed Total Knee Arthroplasty on the Human Femur: A CT-Data Based Study.

End-of-stem pain of the femur is a common problem in revision total knee arthroplasty (TKA). It may be caused by a problematic interaction between stem and bone, but the exact biomechanical correlate is still unknown. The aim of this prospective study was to find out how the stem is positioned in the medullary canal, how the femoral geometry changes due to implantation, and whether the results are influenced by the diameter of the trial. We implanted 16 rotating hinge knee implants into 16 fresh-frozen human femora using the hybrid fixation technique and comparing two reaming protocols. We created 3-dimensional models of the specimens before and after implantation using CT-scans and calculated the differences. The main contact between stem and bone was found at the proximal 30 mm of the stem, especially anterior. We observed two different contact patterns of stem and bone. The cortical thickness was reduced especially at the anterior tip of the stem with a maximum reduction of 1405 ± 501 μm in the standard group and 980 ± 447 μm in the small_trial group, which is a relative reduction of 34 ± 14% (standard group) and 26 ± 14% (small_trial group). The bone experienced a deformation to posterior and lateral. We conclude that the tip of the stem is an important biomechanical region. Different contact patterns between stem and bone as well as the reduction in cortical thickness at the tip of the stem may play a role in the development of end-of-stem pain.

Biomechanical investigation of the hybrid modified cortical bone screw–pedicle screw fixation technique: Finite-element analysis

BackgroundHybrid fixation techniques including the both modified cortical bone trajectory (MCBT) and traditional trajectory (TT) at the L4 and L5 lumbar segment are firstly proposed by our team. Therefore, the purpose of this study is to evaluate and provide specific biomechanical data of the hybrid fixation techniques including the MCBT and TT.MethodsFour human cadaveric specimens were from the anatomy laboratory of Xinjiang Medical University. Four finite-element (FE) models of the L4–L5 lumbar spine were generated. For each of them, four implanted models with the following fixations were established: TT-TT (TT screw at the cranial and caudal level), MCBT-MCBT (MCBT screw at the cranial and caudal level), hybrid MCBT-TT (MCBT screw at the cranial level and TT screw at the caudal level), and TT-MCBT (TT screw at the cranial level and MCBT screw at the caudal level). A 400-N compressive load with 7.5 N/m moments was applied to simulate flexion, extension, lateral bending, and rotation, respectively. The range of motion (ROM) of the L4–L5 segment and the posterior fixation, the von Mises stress of the intervertebral disc, and the posterior fixation were compared.ResultsCompared to the TT-TT group, the MCBT-TT showed a significant lower ROM of the L4–L5 segment (p ≤ 0.009), lower ROM of the posterior fixation (p < 0.001), lower intervertebral disc stress (p < 0.001), and lower posterior fixation stress (p ≤ 0.041). TT-MCBT groups showed a significant lower ROM of the L4–L5 segment (p ≤ 0.012), lower ROM of the posterior fixation (p < 0.001), lower intervertebral disc stress (p < 0.001), and lower posterior fixation stress (p ≤ 0.038).ConclusionsThe biomechanical properties of the hybrid MCBT-TT and TT-MCBT techniques at the L4–L5 segment are superior to that of stability MCBT-MCBT and TT-TT techniques, and feasibility needs further cadaveric study to verify.

Tibial tunnel enlargement is affected by the tunnel diameter-screw ratio in tibial hybrid fixation for hamstring ACL reconstruction

IntroductionThere is no evidence on screw diameter with regards to tunnel size in anterior cruciate ligament reconstruction (ACLR) using hybrid fixation devices. The hypothesis was that an undersized tunnel coverage by the tibial screw leads to subsequent tunnel enlargement in ACLR in hybrid fixation technique.MethodsIn a retrospective case series, radiographs and clinical scores of 103 patients who underwent primary hamstring tendon ACLR with a hybrid fixation technique at the tibial site (interference screw and suspensory fixation) were obtained. Tunnel diameters in the frontal and sagittal planes were measured on radiographs 6 weeks and 12 months postoperatively. Tunnel enlargement of more than 10% between the two periods was defined as tunnel widening. Tunnel coverage ratio was calculated as the tunnel diameter covered by the screw in percentage.ResultsOverall, tunnel widening 12 months postoperatively was 23.1 ± 17.1% and 24.2 ± 18.2% in the frontal and sagittal plane, respectively. Linear regression analysis revealed the tunnel coverage ratio to be a negative predicting risk factor for tunnel widening (p = 0.001). The ROC curve analysis provided an ideal cut-off for tunnel enlargement of > 10% at a tunnel coverage ratio of 70% (sensitivity 60%, specificity 81%, AUC 75%, p < 0.001). Patients (n = 53/103) with a tunnel coverage ratio of < 70% showed significantly higher tibial tunnel enlargement of 15% in the frontal and sagittal planes. The binary logistic regression showed a significant OR of 6.9 (p = 0.02) for tunnel widening > 10% in the frontal plane if the tunnel coverage ratio was < 70% (sagittal plane: OR 14.7, p = 0.001). Clinical scores did not correlate to tunnel widening.ConclusionTibial tunnel widening was affected by the tunnel diameter coverage ratio. To minimize the likelihood of disadvantageous tunnel expansion—which is of importance in case of revision surgery—an interference screw should not undercut the tunnel diameter by more than 1 mm.

Superior Survival of Fully Cemented Fixation Compared to Hybrid Fixation in a Single Design Rotating Hinge Knee Implant.

Clinical observations revealed higher rates of aseptic loosening for hybrid fixated rotating hinge knee implants compared to fully cemented ones. We hypothesize that the use of a fully cemented fixation technique had a higher survival rate for aseptic loosening compared to a hybrid fixation technique in a rotating hinge knee implant. All procedures of patients who were treated with the RT-PLUS rotating hinge knee implant (Smith & Nephew, Memphis, TN) between 2010 and 2018 were included. Primary outcome was revision for aseptic loosening. Kaplan-Meier survivorship and Cox proportional hazard regression analysis were performed to calculate survival rates and hazard ratios. A total of 275 hinge knee implants were placed in 269 patients (60 primary procedures, 215 revisions). Median follow-up was 7.3±3.9 years. In total, 24 components (16 hybrid femur, 2 fully cemented femur, 6 hybrid tibia; all revision procedures) in 19 patients were revised for aseptic loosening. Kaplan-Meier survivorship analysis showed superior survival rates of fully cemented components (femur 97.1%; tibia 100%) compared to hybrid fixated components (femur 89.5%; tibia 95.9%) at the 10-year follow-up. Multivariate Cox hazard analysis showed a significantly higher risk of aseptic loosening for hybrid fixated components, a prior stemmed component and the femoral component. Fully cemented fixation showed superior survival rates for aseptic loosening compared to hybrid fixation in a single design rotating hinge knee implant. A prior stemmed component appears to be a risk factor for aseptic loosening and the femoral component seems to be more prone to loosening.

Mandibular Stability After Sagittal Split Ramus Osteotomy With Hybrid Technique in Asymmetric Patients.

The hybrid technique after bilateral sagittal split ramus osteotomy is an internal fixation method using monocortical mini-plates and additional bicortical positional screws. In this study, we analyzed the postoperative stability of 23 patients with mandibular asymmetry who underwent bilateral sagittal split ramus osteotomy and hybrid fixation with or without LeFort I osteotomy. Anatomical landmarks of the deviated and non-deviated sides of the jaw were established to measure the angle and distance to the reference plane in three-dimensional cone beam computed tomography images. We analyzed the positional changes and correlations of the reference points at preoperative (T1), postoperative 2 weeks (T2), and postoperative 1 year (T3). There were significant differences in preoperative position of the upper and lower molar cervix alveolar crest to the reference plane (U6-X and L6-X) and the condylion angles between deviated and non-deviated sides. Postoperatively (T2-T3), each reference point had no statistically significant positional change. Pearson correlation coefficient between the amount of menton deviation (ME-X at T1) and positional change of menton after surgery (T2-T3) was 0.30, and P value was 0.168. The hybrid fixation technique is an effective fixation method for achieving postoperative stability for mandibular asymmetry.

Comparison of Three Different Surgical Fixation Techniques in Pediatric Forearm Double Fractures.

IntroductionAlthough forearm fractures are one of the most common fractures in children, controversy remains about the optimal fixation technique in the surgical treatment of these fractures. The aim of this study was to compare the results of pediatric patients with a forearm double fracture who underwent open reduction and internal fixation (plate-screw group), elastic intramedullary nailing to both bones (ESIN), and hybrid fixation (the radius or ulna is fixed with the help of ESIN and the other forearm bone is fixed using plate-screw).MethodsA retrospective scan was made of the records of 51 patients with forearm double diaphyseal fractures (19 plate-screw, 18 ESIN, and 14 hybrid fixation). Comparisons were made in respect of the duration of surgery, length of the incision, duration of follow-up, time to union, functional results, and complication rates.ResultsThe study results showed that the surgical incision length and operating time in the hybrid group were statistically significantly shorter than in the plate-screw group (p<0.05). No statistically significant difference was determined between the three groups in respect of the functional results (p>0.05).ConclusionWhen the hybrid fixation technique was compared with other methods, the results were equal or better in terms of surgery time, incision length, time to union, and complications. Therefore, this technique can be used as an effective and reliable method in appropriate pediatric forearm diaphyseal double fractures.