Fixation options for total knee arthroplasty: a comprehensive literature review.

Total knee arthroplasty is a consistently successful, cost-efficient, and highly effective surgical procedure for treating severe knee osteoarthritis. The success and longevity of total knee arthroplasty depend significantly on the fixation method used to secure the prosthetic components. This comprehensive review examines the primary fixation methods (cemented, cementless, and hybrid fixation), analysing their biomechanics, clinical outcomes, advantages, and disadvantages, focusing on recent advances and trends in total knee arthroplasty fixation.

Structural bone grafting for glenoid bone loss in primary anatomic total shoulder arthroplasty: a case series and technique report.

Background: Posterior glenoid bone loss in glenohumeral osteoarthritis poses significant challenges in shoulder arthroplasty. Anatomic total shoulder arthroplasty (TSA) with a humeral head autograft to address the glenoid bone deficiency is an option for these difficult cases. Variable results with this procedure are reported in the literature. This article describes the surgical technique of posterior glenoid bone grafting in TSA using a glenoid implant with hybrid fixation and a series of reported patient functional and radiographic outcomes. Methods: A retrospective chart review of cases from 2015 to 2020 by a single surgeon revealed 10 patients who underwent primary TSA with hybrid glenoid component and posterior glenoid bone grafting. Preoperative and postoperative radiographs were assessed for glenoid inclination, glenoid version, acromiohumeral distance, humeral stem status, and glenoid implant status. Functional outcomes were evaluated by range of motion, strength, and patient-reported clinical outcomes (pain and function on a visual analog scale, Disabilities of the Arm, Shoulder, and Hand score, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons score). Complications and reoperations were also evaluated. Results: Average follow-up was 31.4 months, active forward flexion and external rotation improved on average from 105° to 150° and 20° to 60°, respectively (P < .001) and average abduction improved from 100° to 140° (P < .002). At an average of 26.7 months, patients reported assessments (visual analog scale pain and function, Disabilities of the Arm, Shoulder, and Hand score, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons scores) reveal significant (P < .05) improvement in pain and functional outcomes. Radiographically, at 23.0 ± 20.1 months, all patients demonstrated a well-fixed humeral and glenoid component without evidence of lucent lines. The bone graft used in each patient was well unionized and no radiographic complications were reported. No patients underwent revision surgery, and there was one clinical complication reported, which consisted of a suspected rotator cuff injury at follow-up. Conclusion: Hybrid fixation with structural glenoid bone grafting in TSA resulted in excellent outcomes with no evidence of graft or component failure on follow-up radiographs and significantly reduced pain, improved functional scores, and improved active range of motion.

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

Purpose: 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. Methods: 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. Results: 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). Conclusion: 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 of Evidence: Level III, retrospective cohort study.

Does adjunctive fixation in conjunction with miniplate affect condylar position and morphology after mandibular advancement through bilateral sagittal split ramus osteotomy? A retrospective 3-dimensional CT comparative study.

To minimize condylar positional and morphological changes after mandibular advancement through bilateral sagittal split ramus osteotomy (BSSRO), surgeons add either a bicortical screw or a two-hole plate distal to the conventional single miniplate. Since there have been no previous studies investigating the effect of this combination, our study aimed to evaluate the short- and long-term effects of these adjunctive fixation methods (AFM) on condylar positional and morphological changes after mandibular advancement through BSSRO. This retrospective cohort study included consecutive patients with retruded mandibles who were treated in the Department of Orthognathic and TMJ Surgery at West China Hospital of Stomatology, Sichuan University. The patients were divided into two groups based on the primary predictor variable, which was the addition of AFM - either a single bicortical screw or a two-hole plate in addition to the single miniplate. The primary outcome variable was the condylar positional and morphological changes after mandibular advancement through BSSRO. Three-dimensional facial CT scans were obtained at three different time points (preoperatively - T0, 1 week postoperatively - T1, and 1 year postoperatively - T2) and analyzed using ITK-SNAP, 3D Slicer, and SlicerSALT software. Intergroup comparisons were conducted with an independent t-test, with a p-value of <0.05 considered significant. Correlations between the variables were estimated by Pearson correlation. The study comprised 51 patients (32 females, 19 males; mean age 25.13 ± 4.24 years), involving a total of 81 condyles (21 unilateral and 60 bilateral). There was a significant difference in long-term condylar displacement in favor of AFM along with a single miniplate (p < 0.001). The bicortical screw group recorded less condylar displacement than the two-hole plate group horizontally (0.11 mm vs 0.22 mm) and sagittally (0.03 mm vs 0.17 mm), but more vertically (0.85 mm vs 0.03 mm). Bone formation associated with AFM occurred on all condylar surfaces, compared with only three surfaces in the single miniplate group. The adjunctive method in addition to the single miniplate fixation method showed less condylar displacement and more bone apposition after mandibular advancement through BSSRO. The follow-up duration variable was the only significant determinant for volumetric changes in the condyle.

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

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

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

Background: The 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. Methods: Three 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. Results: No 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. Conclusion: The 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.

Outcomes of Metaphyseal Cones and Stem Fixation Following Rotating Hinge in Complex Primary and Revision Total Knee Arthroplasty.

BACKGROUND: Although hinged prostheses have been used successfully in complex revision total knee arthroplasty (TKA), concerns exist regarding early failure due to aseptic loosening and other mechanical complications. The use of metaphyseal cones and hybrid cement fixation have been studied in unlinked constrained primary or revision TKA, but their impact on the survivorship of hinged prostheses has yet to be investigated. METHODS: We identified a consecutive series of 164 hinged prostheses and collected data on demographics, indications, complications, and re-revisions in patients who had fully cemented versus hybrid stems, with and without metaphyseal cones. A multivariate analysis was performed to identify independent variables associated with re-revision as the primary end point. RESULTS: In total, 84 patients (51.2%) had fully cemented stems, and 80 patients (48.8%) had hybrid stems. Cones were used in 73 patients (44.5%). At a mean follow-up of 3.4 ± 2.2 years, 42 patients underwent re-revision (25.8%), most commonly for infection (12.2%), followed by loosening (6.7%) and periprosthetic fracture (3.7%). Patients who had fully cemented stems had lower re-revision rates than hybrid fixation constructs (19 versus 26%, P = .043). Using multivariable regression, a construct with hybrid fixation with cones (odds ratio = 2.39; P = .037) was an independent risk factor for failure. Utilization of cones alone did not have an effect on re-revision rates at 3.4-year follow-up. CONCLUSIONS: While we found no difference with the use of cones, patients undergoing revision TKA with a hinge prosthesis and fully cemented stems had better overall survivorship than hybrid stems.

Midterm results of modular hinge total knee arthroplasty using cementless osseointegrating stems: low fixation associated complications and good functional outcome in primary and revision knee arthroplasty.

PURPOSE: This study aimed to investigate functional outcome and complications after primary and revision modular H-TKA using hybrid fixation with cementless stems. METHODS: Between 2015 and 2018, 48 patients with 50 implants were included after hybrid implantation of a single design H-TKA system using cementless osseointegrating stems and modular components. Complications and clinical outcome were analysed using Knee Society Score (KSS), the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) and the Short-Form Health Survey 12 (SF-12) score. RESULTS: Indications for implantation were aseptic revision (n = 29, 58%), primary TKA (n = 19, 38%) and two-stage septic revisions (n = 2, 4%). Complications were reported in 26% (n = 12), whereas complications associated with hybrid fixation occurred in 5 (10%) cases, with 2 (4%) requiring revision surgery for aseptic loosening and 3 (6%) treated with an adapted postoperative protocol for perioperative fractures. Implant survivorship was 84% after a mean follow-up of 54 months. Postoperative KSS significantly improved from 51.50 (12-100) to 78.36 (41-99; p < 0.001). The mean WOMAC score was 19.26 (0-55), SF-12 PCS was 41.56 points (22.67-57.66) and SF-12 MCS was 49.21 points (23.87-63.21). CONCLUSION: Hybrid modular implantation in H-TKA provides satisfactory clinical and functional results in primary and revision TKA. Clinical outcomes significantly improve with reduced pain, increased mobility, and good-to-excellent functional scores after implantation. Whilst implant survival is comparable to previous studies and complications associated with hybrid fixation are low, general complication rates are comparably high.

Biomechanical evaluation of novel intra- and extramedullary assembly fixation for proximal humerus fractures in the elderly.

Purpose: A novel intra- and extramedullary assembly fixation method was introduced, which achieved good clinical results in complex proximal humeral fractures; however, evidence of its comparability with traditional fixation is lacking. This biomechanical study aimed to compare it with traditional fixation devices in osteoporotic proximal humeral fractures. Methods: Three-part proximal humeral fractures with osteopenia were created on 12 pairs of fresh frozen humerus specimens and allocated to three groups: 1) lateral locking plate, 2) intramedullary nail, and 3) intra- and extramedullary assembly fixation. The specimens were loaded to simulate the force at 25° abduction. Thereafter, an axial stiffness test and a compound cyclic load to failure test were applied. Structural stiffness, number of cycles loaded to failure, and relative displacement values at predetermined measurement points were recorded using a testing machine and a synchronized 3D video tracking system. Results: In terms of initial stiffness and the number of cycles loaded to failure, the intra- and extramedullary assembly fixation group showed notable improvements compared to the other groups (p <0.017). The mean relative displacement value of measurement points in the intra- and extramedullary assembly fixation group was smaller than that in the other two groups. However, there was no significant difference until 10,000 cycles. The mean relative displacement of the intramedullary nail group (3.136 mm) exceeded 3 mm at 7,500 cycles of loading. Conclusion: In this test model, axial fixation can provide better mechanical stability than non-axial fixation. The intra- and extramedullary assembly fixation is better able to prevent the varus collapse for elderly proximal humeral fractures with posteromedial comminution.

Clinical results of acetabular fracture treatment with hybrid fixation by anterior and posterior approach : A minimally invasive technique.

BACKGROUND: Open reduction and internal fixation have been described as the gold standard for the treatment of acetabular fractures, but the high complications of these surgeries have led surgeons to seek less invasive procedures. In recent years, minimally invasive treatment, such as fixation through the skin have been proposed. The aim was to assess acetabular fracture outcomes of combination of posterior approach (Kocher-Langenbeck [KL]) with anterior percutaneous screw fixation (APSF) with minimally invasive surgery (MIS). METHODS: Between February 2017 and July 2019, 155 patients with acetabular fractures underwent fixation with the KL + APSF approach. For 1 year functional outcomes, radiographic findings, and postoperative complications were evaluated. RESULTS: Of 155 patients with a mean age of 40.16 ± 10.32 years, 82 patients were male and 73 were female. The most common pattern of fracture was both columns (32.9%). The average blood loss was approximately 527 ml. The average operation time was 85 min. The mean length of surgical incision was 113.3 mm. Harris' hip score was excellent in 75.5% of cases. The mean VAS score was approximately 4 and 91.6% of patients returned to pre-trauma activity. In 74.8% of cases, the reduction was anatomical. Complications after surgery were very insignificant and included the following: 2 patients had foot drop within 5 months both patients recovered, 2 patients had femoral nerve palsy and 3 cases of deep vein thrombosis and 1 case of pulmonary thromboembolism were treated. There were four patients with surgical site infections, all of whom recovered and two of the seven patients with osteoarthritis underwent total hip arthroplasty. CONCLUSION: Combining posterior approach with minimally invasive anterior method in fixation and treatment of acetabular fractures is a safe and reliable method and showed significant functional results with minimal complications.

Hybrid fixation versus conventional cage-plate construct in 3-level ACDF: Introduce the "seesaw theory" of stand-alone cage.

STUDY DESIGN: A retrospective study. BACKGROUND: Conventional cage-plate construct (CCP) was widely used in anterior cervical discectomy and fusion (ACDF), but the rigid fixation limits the motion of fused segments. Self-locking stand-alone cage (SSC) was an alternative for ACDF procedures and showed several superiorities. However, the effect of hybrid fixation in 3-level ACDF remains unknown. OBJECTIVE: To assess the clinical and radiological outcomes of hybrid fixation with SSC and CCP against conventional CCP in 3-level ACDF. METHOD: A retrospective review of patients who underwent 3-level ACDF at Renji Hospital between January 2018 and December 2019 was performed. Eighty-three patients met the inclusion and exclusion criteria and were stratified into 2 groups based on the fixation methods. The clinical outcomes, functional outcomes, and radiological parameters were collected and analyzed. RESULTS: No significant difference was observed between the two groups in the mean age, sex, body mass index, hospital stay, and duration of follow-up. The postoperative C2-7 Cobb angle in the CCP group was significantly greater than that in the hybrid group. The rate of cervical proximal junctional kyphosis (CPJK) in the hybrid group was significantly lower than that in the CCP group. The CCP group suffered significantly higher rates of adjacent segment degeneration (ASD) than the hybrid group at 2 years postoperatively. Moreover, the incidence of postoperative dysphagia was lower in the hybrid group. No significant differences were observed in JOA and NDI scores between the two groups. CONCLUSION: The hybrid fixation achieved comparable clinical outcomes against CCP fixation, indicating that hybrid fixation is an alternative procedure in 3-level ACDF.

Minimum 5-Year Clinical Outcomes and Survivorship for a Single Revision Total Knee Arthroplasty System Using Hybrid Fixation and Press-Fit Stems.

BACKGROUND: Hybrid fixation, utilizing diaphyseal press-fit stems and cement fixation in the tibial and femoral metaphyseal areas, has long been a strategy for revision total knee arthroplasty (rTKA). The purpose of this study was to evaluate the clinical outcomes and survivorships of hybrid fixation using a single rTKA revision system with a minimum of 5 years follow-up. METHODS: We reviewed our prospectively collected database to identify 281 patients who underwent rTKA using a single revision system with hybrid fixation and press-fit stems between July 2006 and August 2016. We reviewed the clinical outcome scores, including the Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis index, and Veterans RAND 12 Item Health Survey. We also evaluated the 5 and 10-year survivorships and the indications for reoperations. The cohort had a mean age of 70 years (range, 45.2 to 92.0) and a mean body mass index of 33.4 (range, 17.3 to 55.8). The mean time from rTKA surgery was 11.1 years (range, 5.3 to 15.5). RESULTS: Paired t-test analyses showed significant improvements from preoperative versus postoperative clinical outcome scores (P < .001) for Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis, and Veterans RAND 12 Item Health Survey Physical component. Prosthetic joint infections after index rTKA were the most common failure mode with 29 patients requiring reoperations. Rerevision due to aseptic loosening was uncommon (6 patients) with a cumulative survival rate of 95.2% at 5 years and 94.2% at 10 years. CONCLUSION: The use of this single rTKA system utilizing press fit stems combined with hybrid fixation provided significant improvements in the clinical outcomes and excellent survivorships at 5 and 10 years.

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

BACKGROUND: Investigate 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.

Biomechanical comparisons of dynamic fixators with rod-rod and screw-spacer joints on lumbar hybrid fixation.

BACKGROUND: Hybrid fixators with quite different joint design concepts have been widely to suppress adjacent segment degeneration problems. The kinematic and kinetic responses of the adjacent and transition segments and contact behaviors at the bone-screw interfaces served as the objective of this study. METHODS: The moderately degenerated L4/L5 and mildly degenerative L3/L4 segments were respectively immobilized by a static fixator and further bridged by the rod-rod (Isobar) and screw-spacer (Dynesys) fixator. The joint stiffness and mobility of the rod-rod system and the cable pretension of the screw-spacer system were systematically varied. FINDINGS: The flexion of the screw-spacer system provided higher mobility to the transition segment, reducing adjacent-segment problems. The cable pretension had a minor effect on the construct behavior. However, due to limited joint mobility, the rod-rod system showed higher constraints to the transition segment and induced more adjacent-segment compensations. The increased mobility of the rod-rod joint caused it to behave as a more dynamic fixator that increased adjacent-segment compensations at the transition segment. Comparatively, increasing the joint mobility showed more significant effects on the construct behaviors than decreasing the joint stiffness. Furthermore, increased constraint by the rod-rod joint induced higher stress and risk of loosening at the bone-screw interfaces INTERPRETATION: If the protection of the transition segment is the major concern, the rod-rod system can be used to constrain the intervertebral motion and share the higher loads through the fixator. Otherwise, the screw-spacer system is recommended in situations where higher loads onto the transition disc are allowable.

Periprosthetic distal femur fractures around total knee replacements: A comprehensive review.

With a growing number of patients undergoing total knee replacements globally, coupled with an elderly population, the incidence of periprosthetic fractures around total knee replacements is increasing. As such, this is a highly topical subject that is gaining increasing interest within the orthopaedic community. This review provides a narrative synthesis of the most contemporary literature regarding distal femoral periprosthetic fractures. We review the related epidemiology, initial patient evaluation, the evolution and relevance of the classification systems and treatment options, particularly related to endoprosthetics and hybrid fixation constructs. The latest orthopaedic evidence related to this topic has been included.

The Bone Bridge for Tibial ACL Graft Fixation: A Biomechanical Analysis of Different Tibial Fixation Methods for ACL Reconstruction.

Background: The tibial fixation site is considered the weak link in anterior cruciate ligament (ACL) reconstruction, and conflicting results regarding the biomechanical properties of various fixation methods have been reported. Purpose: To examine knots tied over a bone bridge and its biomechanical properties as a suitable tibial fixation method in ACL reconstruction. Study Design: Controlled laboratory study. Methods: We divided 40 fresh-frozen porcine tibiae into 4 equal groups to evaluate flexor tendon grafts set with standard tibial fixation techniques: (1) bone bridge (BB group), (2) suspension button (SB group), (3) combined interference screw and bone bridge (IFS/BB group), and (4) combined interference screw and suspension button (IFS/SB group). Each construct was subjected to cyclic loading (1500 cycles, 50-250 N, 1 Hz) with a servohydraulic materials testing machine to measure elongation; load-to-failure testing (displacement rate: 25 mm/s) was then performed. Load to failure, stiffness, and yield load were compared between constructs using 1-way analysis of variance. Results: The hybrid fixation constructs (IFS/BB and IFS/SB groups) showed significantly better biomechanical properties than the isolated extracortical fixation constructs (BB and SB groups) (P < .05 for all). There were no differences between the isolated extracortical fixation constructs or between the hybrid fixation constructs in elongation or load to failure; however, stiffness of the IFS/BB group was significantly higher than that of the IFS/SB group (175.3 ± 16.6 vs 144.9 ± 20.1 N/mm, respectively; P < .05). Stiffness between the SB and BB groups was not significantly different. Conclusion: Hybrid fixation had superior biomechanical performance compared with isolated extracortical fixation. However, tibial graft fixation using a bone bridge either as isolated extracortical fixation or combined with an interference screw for hybrid fixation showed equivalent biomechanical properties compared with suspension button-based graft fixation. Clinical Relevance: The clinical use of a bone bridge for tibial graft fixation could reduce the cost for ACL reconstruction and lower the rate of implant-associated issues.

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

INTRODUCTION: There 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. METHODS: In 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. RESULTS: Overall, 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. CONCLUSION: Tibial 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.

Novel metaphyseal porous titanium cones allow favorable outcomes in revision total knee arthroplasty.

INTRODUCTION: Loosening and migration are common modes of aseptic failure following complex revision total knee arthroplasty (rTKA). Metaphyseal cones allow surgeons to negotiate the loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing rTKA utilizing a novel metaphyseal cone system with stems of variable length and fixation methods. METHODS: This two-center retrospective study examined all patients who underwent rTKA with a novel porous, titanium tibial or femoral cone in combination with a stem of variable length and fixation who had a minimum follow-up of 2-years. Outcome analysis was separated into tibial and femoral cones as well as the stem fixation method (hybrid vs. fully cemented). RESULTS: Overall, 123 patients who received 156 cone implants were included (74 [60.2%] tibial only, 16 [13.0%] femoral only, and 33 [26.8%] simultaneous tibial and femoral) with a mean follow-up of 2.76 ± 0.66 years. At 2-years of follow-up the total cohort demonstrated 94.3% freedom from all-cause re-revisions, 97.6% freedom from aseptic re-revisions, and 99.4% of radiographic cone osteointegration. All-cause revision rates did not differ between stem fixation techniques in both the tibial and femoral cone groups. CONCLUSION: The use of a novel porous titanium femoral and tibial metaphyseal cones combined with stems in patients with moderate to severe bone defects undergoing complex revision total knee arthroplasty confers excellent results independent of stem fixation technique. LEVEL OF EVIDENCE: IV, case series.

Single staged buttress plating with constrained knee arthroplasty for distal femur fractures in the elderly.

Treatment options for distal femur fractures include open reduction internal fixation (ORIF), arthroplasty, or a hybrid of both. We present a 76 year old female with left knee pain secondary to known osteoarthritis, known lateral condyle insufficiency fracture, and an acute medial condyle fracture. In order to solve the acute and chronic problems in a single procedure, a combined ORIF and constrained condylar knee (CCK) arthroplasty was performed. Arthroplasty alone would have required a highly constrained distal femur replacement, and ORIF alone would have caused prolonged immobilization and continued morbidity from unaddressed chronic problems. We chose a CCK as a less constrained implant would not have protected our ORIF which contained the medial collateral ligament attachment. This technique avoids the complications of ORIF alone, and avoids the known complications of increased constraint in total knee arthroplasty.

Comparison of two different types of hybrid Tibial fixations for anterior cruciate ligament reconstruction: a prospective comparative cohort study.

BACKGROUND: Previous studies have compared different kinds of fixations for anterior cruciate ligament reconstruction. Nevertheless, there is no optimal method to date. To the best of authors' knowledge, there is no article discussing the combination of adjustable suspensory device and interference screw for hybrid tibial fixation. METHODS: In total, 66 patients (n = 34, adjustable suspensory device and interference screw; n = 32, cortical screw and interference screw) were analyzed. Their International Knee Documentation Committee score and Tegner activity level scale were evaluated before and after a 2-year follow-up. The Single Assessment Numeric Evaluation score was evaluated after a 2-year follow-up. Physical exams such as range of motion, anterior knee pain (VAS > = 3) and Lachman test were assessed before and at least 12 months after surgery. To evaluate tunnel widening, anteroposterior and lateral view radiography was conducted 1 day and at least 12 months after surgery. A more than 10% change was considered tibial tunnel widening. Mann-Whitney U test, independent t test, paired t test, Fisher's exact test and chi-squared test were used to compare the variables. Linear and logistic regression models were applied to adjust for potential confounders. RESULTS: No variable except gender (P = 0.006) showed significant difference with regard to demographic data. After adjustment, there was no statistically significant difference between the groups regarding post-operative physical exams. Patients who used adjustable suspensory device and interference screw had lower post-operative Single Assessment Numeric Evaluation score (adjusted ß - 8.194; P = 0.017), Tegner activity level scale (adjusted ß - 1.295; P = 0.001) and pre-operative degrees of knee flexion (adjusted ß - 2.825; P = 0.026). Less percentage of tunnel widening in the lateral view of radiographs was seen in patients in group of adjustable suspensory device and interference screw (adjusted ß - 1.733; P = 0.038). No significant difference was observed in the anteroposterior view of radiographs (adjusted ß - 0.667; P = 0.26). CONCLUSION: In these 66 patients, we observed less tibial tunnel widening and lower post-operative functional scores in the group of adjustable suspensory device and interference screw. Both groups displayed similar outcomes of physical exams as well as improvement after operation. The proposed method may become an alternative option. Nonetheless, the quality of our study is still limited, and thus further studies are warranted to determine the efficacy and further application. TRIAL REGISTRATION: Joint Institutional Review Board of Taipei Medical University, Taipei, Taiwan (No: N201805094 ). STUDY DESIGN: Prospective comparative cohort study; Level of evidence, II.