Impact of fractured tibia implant fixation devices on bone stiffness during bending test.

This study focuses on evaluating the failure resistance of a previously reduced tibia with internal fixation implants as PLate (PL) or InterMedullary Nail (IMN), subjected later to a tibial lateral trauma. To replicate this type of trauma, which can be caused by a road accident, a three-point bending test is considered using experimental tests and numerical simulations. The withstand evaluation of the tibia-PL and tibia-IMN structures was conducted by following the load transfer through, the bone and the used implants. The analysis, up to tibia failure, required the use of an elasto-plastic behavior law coupled to damage. The model parameters were identified using experimental tests. Il was shown that the tibia-IMN structure provided a bending resistant load up to three-times higher than the tibia-PL. In fact, the used screws for plate fixation induced a high level of stress in the vicinity of threaded region, leading to a crack initiation and a damage propagation. However, in tibia-IMN structure the highest stress was generated in the trapped zone between the loader and the nail, promoting crack formation. From a biomechanical point of view, the structure with IMN is safer than the structure with PL, whose fixation induces earlier damage in bone.

Computational analysis of the biomechanical stability of internal fixation of the lateral tibial plateau fracture: A mechanical stability study.

The selection of internal fixation as the primary fixation modality for the patient is one of the challenges for the surgeon treating the patient in question. A model of the lateral tibial plateau fracture was established. Three different configurations of internal fixators namely L bone plate, T bone plate, and screw-washer were analyzed. Three stages after surgery were simulated to assess the displacement of bone plates, screws, washers, and the stress shielding ratio in the fracture area.At three stages after surgery, the T bone plate showed better stability for patients during rehabilitation compared with the remaining two schemes, and the screw-washer scheme was the least stable due to the larger internal fixation displacement and stress shielding ratio in the fracture area. In contrast, the L bone plate scheme showed better stability in the early stages after surgery but was second only to the screw-washer scheme in the middle and late stages after surgery. The T bone plate showed better stability and became a new selection for surgeons to treat related patients. At three stages after surgery, the T bone plate has better biomechanical stability compared to the L bone plate and screw-washer schemes.

Long-term patient reported outcome measures and kneeling function in patients with tibial intramedullary nails.

INTRODUCTION: Anterior knee pain (AKP) is a common complaint following intramedullary nail (IMN) insertion for tibial shaft fractures. There is a lack of long-term patient reported outcome data following tibial IMN, with conflicting evidence of the role of nail protrusion on AKP. In this study, we assess the long-term patient reported outcome measures and kneeling function in patients with tibial IMNs and compare the results with IMN protrusion, measured radiologically. MATERIALS AND METHODS: A retrospective cohort of 128 patients, from a single UK centre, were invited to participate in the study, to complete a Kujala score, KOOS, EQ-5D-5L and a four-posture kneeling assessment. We report the outcomes of 45 patients at an average follow-up of 6.9 years. RESULTS: The mean Kujala score was 80.7. The mean KOOS score was 83.2, 83.9, 85.8, 70.7 and 72.8 for symptoms, pain, daily living, sport and quality of life, respectively. We found 20.5% of patients experienced daily AKP. Pain and fear of pain were the most common limiting factors in the kneeling assessment. No significant correlation was found between the KOOS or Kujala score and nail-plateau distance, nail-anterior cortex distance, or the overall nail prominence. CONCLUSION: AKP affects a subset of patients more than five years post-tibial IMN, limiting their ability to kneel and other functions of daily living. Tibial IMN prominence does not seem to be associated with AKP.

Percutaneous injection of autologous platelet gel accelerate healing in diabetic tibial non union: On going longitudinal study.

INTRODUCTION: In this study the tibial shaft fracture non unions in diabetes mellitus are evaluated with percutaneous autologous platelet gel supplementation to accelerate union are compared with individually matched control group with autologous iliac crest bone marrow aspirate injection. MATERIAL AND METHODS: This present study was carried out on tibial non unions in diabetic patients recruited in an ongoing longitudinal study over a period of 2006 to 2017, treated by one surgeon at one institute, are included in this report. Each of 18 established tibial atrophic, aseptic non unions treated by percutaneous autologous platelets and iliac crest bone marrow aspirate were followed up on regular basis up till 9 months. The healing of non union was assessed clinically by painless full weight bearing and the radiological union was judged by bridging callus formation observed on at least 3 of 4 cortices in anteroposterior and lateral views. RESULTS: Union was observed in 17 (94.4 %) patients of the autologous platelet group. The average time to union was 9.2 weeks (range 8 to 18 weeks) after percutaneous autologous platelet injection (P < 0.0517) .In the control group, union was observed in 14 (77.8 %) patients (P = 0.672). The average time to union following percutaneous bone marrow injection was 11.6 weeks (range 9 to 28 weeks). The proximal 1/3 shaft non union healed comparatively faster than the distal 1/3 shaft tibia (P ≤ 0.0612). No correlation was observed between the comminuted and non comminuted fracture non union (P = 0.789). A significant correlation was noted as regards the non union healing time duration in patients who were on insulin and oral hypoglycemic drugs (P ≤ 0.001) and also about the total duration of diabetes mellitus in years (P ≤ 0.003). CONCLUSION: This investigation showed that percutaneous autologous platelet gel delivery is sufficient method to obtain union in diabetic tibial fracture non unions, which is less invasive procedure than bone marrow injection. The efficacy of this autologous platelets is once again well established and this study reinforced categorically the previously published report by the author.

Screw placement through a higher medial portal provides better initial stability in arthroscopic ACL tibial avulsion fracture fixation: a finite element analysis.

OBJECTIVE: The objective of this study was to investigate the initial stability of different screw placements in arthroscopic anterior cruciate ligament (ACL) tibial avulsion fracture fixation. METHODS: A three-dimensional knee model at 90° flexion was utilized to simulate type III ACL tibial avulsion fracture and arthroscopic screw fixation through different portals, namely the central transpatellar tendon portal (CTP), anterolateral portal (ALP), anteromedial portal (AMP), lateral parapatellar portal (LPP), medial parapatellar portal (MPP), lateral suprapatellar portal (LSP), medial suprapatellar portal (MSP). A shear force of 450 N was applied to the finite element models at 30° flexion to simulate the failure condition. The displacement of the bony fragment and the volume of the bone above 25,000 µ-strain (damaged bone volume) were calculated around the screw path. RESULTS: When the screw was implanted through CTP, the displacement of the bony fragment reached the maximum displacement which was 1.10 mm and the maximum damaged bone volume around the screw path was 148.70 mm3. On the other hand, the minimum displacement of the bony fragment was 0.45 mm when the screw was implanted through LSP and MSP. The minimum damaged bone volume was 14.54 mm3 around the screw path when the screw was implanted through MSP. CONCLUSION: Screws implanted through a higher medial portal generated less displacement of the bony fragment and a minimum detrimental strain around the screw path. The findings are clinically relevant as they provide biomechanical evidence on optimizing screw placement in arthroscopic ACL tibial avulsion fracture fixation.

Osteosynthesis by locking plate for proximal tibial fractures.

INTRODUCTION: Treatment of proximal tibial fractures is known to be difficult. We report our own experience of the treatment of these fractures and evaluate our results. The hypothesis was that the clinical and radiological results were good. MATERIAL AND METHOD: From January 2004 to October 2008, fourteen AO-type 41A2-3 and C1 fractures have been treated with a LCP locking plate (8 women and 6 men, average age 60.42). Plating was performed either with an open approach or a minimal invasive approach. Clinical and radiological follow-up was carried out looking for range of motion of the knee joint and autonomy level. RESULTS: Mean follow-up was 32.63 months (12-70). Range of motion was maintained with a mean arch of 117.5° Autonomy was maintained in all cases. Professional, domestic and sports activities were unchanged. No infection or general complication occurred. Bone fusion was obtained in all cases after an average of 13.28 weeks. 6° of valgus deformation, already seen immediately postoperatively was observed once. Secondary displacement was observed in 6 cases, with an average of 2.83° DISCUSSION-CONCLUSION: We report good radiological results, with only one initial malalignment. The hypothesis was confirmed. However, X-ray analysis at consolidation shows 6 secondary displacements, without any satisfactory explanation. Though the clinical consequences of these malunions are minimal. Osteosynthesis with plate, in the sight of this study, yields good clinical results. Radiological evolution concerning the evolution of bone axes puts the emphasis on careful operative technique and adequate time to weight bearing. LEVEL OF EVIDENCE: retrospective study, IV.

Evaluation of distal tibia slope in pilon fractures after surgical fixation.

INTRODUCTION: Alteration of sagittal alignment during fracture fixation directly impacts ankle motion in dorsiflexion and plantarflexion. Previously research measured the anterior distal tibia angle (ADTA) in a normal healthy population. The null hypothesis for this study is that ADTA is restored to normal range following unstable pilon fractures. The aim of this study is to identify the range of the ADTA in distal tibia fractures after surgical fixation, compared to a previously published normal population. MATERIAL AND METHODS: A retrospective review of operative distal tibia fractures (AO/OTA classification 43A and 43C - 43B were excluded due to lower likelihood of fracture changing the ADTA) was performed. ADTA on lateral radiograph was measured as the angle relative to the tibia shaft. RESULTS: 100 patients with post-operative radiographs that met inclusion criteria were analyzed. The average ADTA was 6.9° (⌠=4.62°) with a maximum slope of 19.2° (i.e. anterior orientation) and a minimum of -3.3° (i.e. posterior orientation). The uninjured population had an average ADTA of 6.0° (range -2.0°-14°, ⌠=3.0°). CONCLUSION: This analysis shows the average distal tibia sagittal alignment in the post-surgical group is similar to a normal, uninjured population. Large alterations in ADTA would directly impact the ankle in the plane of motion (i.e. negative ADTA would decrease ankle dorsiflexion). Considering ADTA as an objective intra-operative parameter optimizes sagittal plane alignment.

Biomechanical evaluation of different medial column fixation patterns for valgus pilon fractures.

BACKGROUND: The purpose of this study was to perform a biomechanical analysis to compare different medial column fixation patterns for valgus pilon fractures in a case-based model. METHODS: Based on the fracture mapping, 48 valgus pilon fracture models were produced and assigned into four groups with different medial column fixation patterns: no fixation (NF), K-wires (KW), intramedullary screws (IS), and locking compression plate (LCP). Each group contained wedge-in and wedge-out subgroups. After fixing each specimen on the machine, gradually increased axial compressive loads were applied with a load speed of one millimeter per minute. The maximum peak force was set at 1500 N. Load-displacement curves were generated and the axial stiffness was calculated. Five different loads of 200 N, 400 N, 600 N, 800 N, 1000 N were selected for analysis. The specimen failure was defined as resultant loading displacement over 3 mm. RESULTS: For the wedge-out models, Group-IS showed less displacement (p < 0.001), higher axial stiffness (p < 0.01), and higher load to failure (p < 0.001) than Group-NF. Group-KW showed comparable displacement under loads of 200 N, 400 N and 600 N with both Group-IS and Group-LCP. For the wedge-in models, no statistical differences in displacement, axial stiffness, or load to failure were observed among the four groups. Overall, wedge-out models exhibited less axial stiffness than wedge-in models (all p < 0.01). CONCLUSIONS: Functional reduction with stable fixation of the medial column is essential for the biomechanical stability of valgus pilon fractures and medial column fixation provides the enough biomechanical stability for this kind of fracture in the combination of anterolateral fixation. In detail, the K-wires can provide a provisional stability at an early stage. Intramedullary screws are strong enough to provide the medial column stability as a definitive fixation. In future, this technique can be recommended for medial column fixation as a complement for holistic stability in high-energy valgus pilon fractures.

Quadriceps muscle quality and quantity following tibial plateau fracture repair.

PURPOSE: To investigate the qualitative and quantitative changes seen in quadriceps muscles [QM] following tibial plateau fracture and surgery. METHODS: A consecutive series of patients with an isolated tibial plateau fracture presenting to a single academic center were enrolled and prospectively followed. Bilateral knee MRIs were performed preoperatively and 3 and 12 months postoperatively to assess quantity and quality of the quadriceps muscles. All patients underwent tibial plateau operative repair and were made non-weight-bearing for 10 weeks postoperatively then advanced to weight-bearing as tolerated. Functional status assessed via the short musculoskeletal functional assessment (SMFA); knee range of motion [ROM]; vastus medialis oblique [VMO] and vastus lateralis [VL] muscle quantity (axial width, cross sectional area [CSA] and volume) on injured and contralateral limb; VMO, sartorius, semi-membranous and biceps femoris [BF] muscle quality (fat and water content, and proton density fat fraction). All muscle quantitative and qualitative measurements were compared across all time points. RESULTS: Ten patients were included in the final analysis, 6 males and 4 females, with average age of 43.62 ± 16.3 years. While the VMO and VL axial width and CSA were significantly decreased at 3 months preoperatively, this was not statistically significant. There was no significant difference between any QM quantitative measurements at any time points. There was no difference in fat content, water content or PDFF at any time point for the VMO, sartorius, semi-membranous and BF muscles. Regression analysis also showed no association between 12-month SMFA scores and knee ROM with VMO/VL CSA at 1 year. CONCLUSIONS: QM quantity and quality do not significantly change at 3 months and 1 year postoperatively following tibial plateau fracture surgery. LEVEL OF EVIDENCE: Prognostic Level II.

Effect of early weight bearing program with conventional physiotherapy on functional outcomes in surgically treated proximal tibia fracture: a pilot randomized controlled trial.

INTRODUCTION: Patients are often instructed to avoid weight bearing on the proximal tibia for 6 - 12 weeks post-surgery to avoid fracture fixation failure. However, delayed weight bearing leads to delayed mobility, causing difficulties in daily activities; problems such as pain, limited knee ROM, reduced quadriceps muscle strength, and impaired functional outcomes are reported in long-term follow-up. This study primarily aimed to evaluate the feasibility and explore the effect size. The secondary aim was to determine the effectiveness of early weight bearing along with conventional physiotherapy on functional outcomes. MATERIALS AND METHODS: A single-blinded pilot randomized controlled trial with 30 participants with proximal tibia type I, II, and III fractures were included; they were randomized using computer-based software. Seven patients were lost to follow-up. Group I received early weight bearing along with conventional physiotherapy whereas Group II received restricted weight bearing along with conventional physiotherapy. Assessments were made on post-operative day 3 (POD-03), at discharge, at 6 weeks, and at 12 weeks. Radiographs were recorded immediately after the operation, at discharge, and at 12 weeks. RESULTS: A full-scale RCT is feasible with an effect size between 0.3 - 0.7. A statistically significant difference (p < 0.05) was found within both groups 12 weeks post-surgery in all outcome measures; the difference was more prominent in the intervention group. A statistically significant difference (p < 0.05) was found between both the groups post-12 weeks in all outcome measures except quadriceps isometric muscle strength. CONCLUSION: A full-scale RCT for early weight bearing along with conventional physiotherapy for patients operated for Type I, II, and III proximal tibia fracture is feasible. Early weight bearing along with conventional physiotherapy could have a positive effect on reducing patient's pain perception and increasing knee joint mobility, quadriceps isometric muscle strength, knee function, and quality of life without any adverse effects. TRIAL REGISTRATION: ClinicalTrialsRegistry.gov (CTRI/2022/10/046797).

Larger lateral hinges increase the probability of Takeuchi type II and III fractures in high tibial osteotomy.

PURPOSE: Lateral hinge fractures are the main complications in the high tibial osteotomy to treat varus deformities. The aim of present study is to answer the question whether the lateral hinge length (H) has an effect on the type of fracture and required force during the opening in high tibia osteotomy. It was hypothesized in this comparative research that extending the hinge length increased opening force and probability of a type II and type III fractures. METHODS: A monoplanar medial open wedge osteotomy with different intact hinge lengths varying from 9 to 32 mm was performed in 20 ostrich bones. A biomechanical experiment using unidirectional tensile testing apparatus was performed to open the wedge, and the required force was increased until a 10 mm opening was reached; then, the presence of fracture in the lateral cortex and its direction were evaluated. Lateral hinge fracture type based on direction was classified as suggested by Takeuchi et al. RESULTS: Fracture that grows along the osteotomy line (type I) was observed in 4 samples with the mean hinge length (H) of 11 ± 1.54 mm. For seven bones with Takeuchi fracture type II, with downward crack propagation, the mean H was 16 ± 3.36 mm. For the mean H of 25 ± 6.53 mm, the crack propagated upward to the cutting path, displaying a Takeuchi type III fracture in seven samples. The statistical analysis showed that the fracture type significantly depends on the hinge length (P value < 0.05). Also, the mean opening force significantly increased with hinge lengthening (P value < 0.05). The peak forces at crack initiation were 41.8 ± 21.9, 115.2 ± 41.5, and 167 ± 135.3 N, respectively, for the fracture types I, II, and III samples. CONCLUSION: The lateral cortical hinge length was significantly associated with hinge fracture type. The experimental tests indicated that the hinge lengthening increases the risk of type II and III fractures, as classified by Takeuchi.

What Is the Patient-reported Outcome and Complication Incidence After Operative Versus Nonoperative Treatment of Minimally Displaced Tibial Plateau Fractures?

BACKGROUND: Much controversy remains about whether minimally displaced tibial plateau fractures should be treated operatively or nonoperatively. It is generally accepted that gaps and stepoffs up to 2 mm can be tolerated, but this assumption is based on older studies using plain radiographs instead of CT to assess the degree of initial fracture displacement. Knowledge regarding the relationship between the degree of fracture displacement and expected functional outcome is crucial for patient counseling and shared decision-making, specifically in terms of whether to perform surgery. QUESTIONS/PURPOSES: (1) Is operative treatment associated with improved patient-reported outcomes compared with nonoperative treatment in minimally displaced tibial plateau fractures (fractures with up to 4 mm of displacement)? (2) What is the difference in the risk of complications after operative versus nonoperative treatment in minimally displaced tibial plateau fractures? METHODS: A multicenter, cross-sectional study was performed in patients treated for tibial plateau fractures between 2003 and 2019 at six hospitals. Between January 2003 and December 2019, a total of 2241 patients were treated for tibial plateau fractures at six different trauma centers. During that time, the general indication for open reduction and internal fixation (ORIF) was intra-articular displacement of > 2 mm. Patients treated with ORIF and those treated nonoperatively were potentially eligible; 0.2% (4) were excluded because they were treated with amputation because of severe soft tissue damage, whereas 4% (89) were excluded because of coexisting conditions that complicated outcome measurement including Parkinson disease, cerebrovascular accident, or paralysis (conditions causing an inability to walk). A further 2.7% (60) were excluded because their address was unknown, and 1.4% (31) were excluded because they spoke a language other than Dutch. Based on that, 1328 patients were potentially eligible for analysis in the operative group and 729 were potentially eligible in the nonoperative group. At least 1 year after injury, all patients were approached and asked to complete the Knee injury and Osteoarthritis Outcome Scale (KOOS) questionnaire. A total of 813 operatively treated patients (response percentage: 61%) and 345 nonoperatively treated patients (response percentage: 47%) responded to the questionnaire. Patient characteristics including age, gender, BMI, smoking, and diabetes were retrieved from electronic patient records, and imaging data were shared with the initiating center. Displacement (gap and stepoff) was measured for all participating patients, and all patients with minimally displaced fractures (gap or stepoff ≤ 4 mm) were included, leaving 195 and 300 in the operative and nonoperative groups, respectively, for analysis here. Multivariate linear regression was performed to assess the association of treatment choice (nonoperative or operative) with patient-reported outcomes in minimally displaced fractures. In the multivariate analysis, we accounted for nine potential confounders (age, gender, BMI, smoking, diabetes, gap, stepoff, AO/OTA classification, and number of involved segments). In addition, differences in complications after operative and nonoperative treatment were assessed. The minimum clinically important differences for the five subscales of the KOOS are 11 for symptoms, 17 for pain, 18 for activities of daily living, 13 for sports, and 16 for quality of life. RESULTS: After controlling for potentially confounding variables such as age, gender, BMI, and AO/OTA classification, we found that operative treatment was not associated with an improvement in patient-reported outcomes. Operative treatment resulted in poorer KOOS in terms of pain (-4.7 points; p = 0.03), sports (-7.6 points; p = 0.04), and quality of life (-7.8 points; p = 0.01) compared with nonoperative treatment, but those differences were small enough that they were likely not clinically important. Patients treated operatively had more complications (4% [7 of 195] versus 0% [0 of 300]; p = 0.01) and reoperations (39% [76 of 195] versus 6% [18 of 300]; p < 0.001) than patients treated nonoperatively. After operative treatment, most reoperations (36% [70 of 195]) consisted of elective removal of osteosynthesis material. CONCLUSION: No differences in patient-reported outcomes were observed at midterm follow-up between patients treated surgically and those treated nonsurgically for tibial plateau fractures with displacement up to 4 mm. Therefore, nonoperative treatment should be the preferred treatment option in minimally displaced fractures. Patients who opt for nonoperative treatment should be told that complications are rare, and only 6% of patients might undergo surgery by midterm follow-up. Patients who opt for surgery of a minimally displaced tibial plateau fracture should be told that complications may occur in up to 4% of patients, and 39% of patients may undergo a secondary intervention (most of which are elective implant removal). LEVEL OF EVIDENCE: Level III, therapeutic study.

The validation of computed tomography derived radiodensity measurements of bone healing using histopathology.

BACKGROUND: The early identification of delayed bone healing or a non-union is vital for prompt treatment and superior patient outcomes. Current techniques rely heavily on operator skill for interpretation and hence their reliability and repeatability may be inconsistent. This study assessed the application of computed tomography (CT) derived densiometric measurements as a quantitative tool for the assessment of bone healing. METHODS: This prospective, longitudinal, method comparison study was performed using a recognised sheep tibial ostectomy model. Secondary bone healing was assessed at 2, 4, 6, and 8 weeks after the ostectomy was performed. CT densiometric measures of bone healing (Hounsfield units) were taken of the cis, trans, cranial and caudal cortices relative to the bone plate, with histological measurements (percentage of ossification) sourced from the same areas. Cis cortical densiometric data points were excluded from analysis due to significant beam hardening artefact from the bone plate (P < 0.001). A univariable linear regression was performed on the remaining data using averaged radiodensity (independent variable) and histomorphometric (dependent variable) measurements. RESULTS: The two measurements were significantly correlated (R2 = 0.623, P = 0.020) with a clear positive trend identified. CONCLUSION: This study suggests that radiodensity measurements may be a useful diagnostic and management tool for the monitoring of indirect bone healing.

Are extra locking bolts or fibular plating more important in extreme nailing of distal tibia fractures? A cadaveric biomechanical analysis.

OBJECTIVES: In far-distal extra-articular tibia fracture "extreme" nailing, debate surrounds the relative biomechanical performance of plating the fibula compared with extra distal interlocks. This study aimed to evaluate several constructs for extreme nailing including one interlock (one medial-lateral interlock), one interlock + plate (one medial-lateral interlock with lateral fibula compression plating), and two interlocks (one medial-lateral interlock and one anterior-posterior interlock). METHODS: Fifteen pairs of fresh cadaver legs were instrumented with a tibial nail to the physeal scar. A 1 cm segment of bone was resected from the distal tibia 3.5 cm from the joint and an oblique osteotomy was made in the distal fibula. We loaded specimens with three different distal fixation constructs (one interlock, one interlock + plate, and two interlocks) through 10,000 cycles form 100N-700 N of axial loading. Load to failure (Newtons), angulation and displacement were also measured. RESULTS: Mean load to failure was 2092 N (one interlock), 1917 N (one interlock + plate), and 2545 N (two interlocks). Linear mixed effects modeling demonstrated that two interlocks had a load to failure 578 N higher than one interlock alone (95 % CI, 74N-1082 N; P = 0.02), but demonstrated no significant difference between one interlock and one interlock + plate. No statistically significant difference in rates or timing of displacement >2 mm or angulation >10° were demonstrated. CONCLUSIONS: When nailing far-distal extra-articular tibia and fibula fractures, adding a second interlock provides more stability than adding a fibular plate. Distal fibula plating may have minimal biomechanical effect in extreme nailing.

Fixation of Proximal Tibial Fractures with Intramedullary Nail and Immediate Weightbearing: A Beneficial Alternative.

Newer intramedullary (IM) nails have become another option in the fixation of proximal tibia fractures. There is limited data on the successful use of these implants in intra-articular and extra-articular fractures of the proximal tibia, and no studies assessing the ability of these implants to maintain alignment with early weight bearing. Our objective was to determine whether immediate weight bearing after IM fixation, with or without supplemental plate or screw fixation, of proximal third tibial fractures (OTA/AO 41A-C) results in a change in alignment prior to union. 35 patients with 39 proximal tibia fractures from 2015 to 2020, all treated with IM nailing with or without supplemental plate or screw fixation, all made weight-bearing as tolerated following surgery, were included. The main outcomes were change in medial proximal tibial angle (MPTA) and posterior proximal tibial angle (PPTA) from initial post-operative films to final follow up. 12 fractures were OTA/AO 41 type A, 14 were type B, and 13 were type C. Mean initial MPTA was 87.0 +/-2.53 degrees, while mean initial PPTA was 79.6 +/- 3.50 degrees. The mean change in MPTA was 0.048 +/- 2.8 degrees (P=0.92), and mean change in PPTA was 0.264 +/- 3.67 degrees. 92.3% of fractures had normal final coronal plane alignment, with MPTA between 85.0 and 90.0 degrees. 89.7% of fractures had normal final sagittal plane alignment, with PPTA between 77.0 and 84.0 degrees. No patients required reoperation for malalignment. In OTA/AO type 41 fractures, immediate weight bearing after IM nail fixation, with or without supplemental plate or screw fixation when indicated, leads to minimal change in final coronal or sagittal alignment, and was well tolerated in most patients. [authors blinded for review].

Toddler fractures immobilisation and complications: A retrospective review.

BACKGROUND: A Toddler's Fracture (TF) is classically an isolated, nondisplaced, distal-third diaphyseal tibial spiral fracture in younger children. A TF is stable and has a low risk of complication. There is lack of uniformity as to the optimal treatment for TF. Immobilisation with full above knee casting, below knee casting, splinting, controlled ankle motion boots and no immobilisation are all strategies currently in use. There is limited data from European centres regarding those treated without immobilisation. METHODS: A retrospective review of electronic medical and radiology records was performed to identify all children presenting to a multisite department of paediatric emergency medicine in Ireland from January to December 2022. Those with radiologically confirmed TF or a presumptive diagnosis of TF were included. Data retrieved for each child included initial treatment and the number of and reason for ED reattendances relating to the injury in the 6-month period following the injury. RESULTS: 166 children were identified, 96 with radiologically confirmed TF and 70 with presumptive diagnosis TF. Girls accounted for 47 % of presentations. Fall from a standing height (33 %) was the most common mechanism. 13 % (22/166) children were managed without immobilisation. Those with radiologically confirmed fracture (91/96) were significantly more likely to be immobilised than those with a presumptive diagnosis (53/70) (p = 0.001). In total 28 patients (17 % of total) represented to the ED within 6 months. The representation rate in those immobilised was 17 %, while in those not immobilised was 13 % (p = 0.66). CONCLUSION: In this cohort, those with no radiological evidence of fracture are more likely to be managed without immobilisation. There was no significant difference in PED representations between those immobilised and not immobilised.

Biomechanical comparisons of plate placement for medial tibial plateau fractures (Schatzker type IV): A biomechanical study using porcine tibias.

INTRODUCTION: Biomechanical studies on medial tibial plateau fractures (MTPFs) (Schatzker classification type IV) are currently few, while studies using locking plates (LPs) placed on medial proximal tibias are unavailable. Hence, we compared the biomechanical properties of plate osteosynthesis at the medial and anteromedial placements using large- and small-fragment LPs in porcine bones. MATERIALS AND METHODS: MTPFs were internally fixed using LPs on 40 porcine tibias. Specimens were equally divided into four groups: medial placement using a large-fragment LP (LPs for the medial (LM) group), anteromedial placement using a large-fragment LP (LAM group), medial placement using a small-fragment LP (SM group), and anteromedial placement using a small-fragment LP (SAM group). The translation patterns of the constructs in each group were examined by cycling loading test (displacement and translation along the mechanical axis at 10-100, 100-500, 500-1000, 1000-1500, and 1500-2000 cycles). Then, articular gaps and step-off changes after 2000 cycles were compared among the four groups. RESULTS: One-way analysis of variance (ANOVA) revealed no significant differences in displacement and translation during cyclic loading. One-way ANOVA followed by post hoc analysis revealed that the anterior gap was lower in LPs for the medial (LM) than in SM (P = 0.029) and SAM (P = 0.0026). The central gap was also lower in LM than in SM (P = 0.042) and SAM (P < 0.001), and it was lower in LAM than in SAM (P = 0.047). Likewise, the posterior gap was lower in LM than in LAM (P = 0.025) and SAM (P < 0.001). Furthermore, the central step-off of SAM was higher than that of LM, LAM, and SM (P < 0.001, P = 0.0014, and P = 0.0077, respectively). The posterior step-off was lower in LM than in SAM and LAM (P = 0.037 and P < 0.001), and it was also lower in SM than in SAM (P = 0.0082). CONCLUSION: Medial LP placement for MTPFs in porcine bones resulted in significantly lower posterior step-offs after cyclic loading than anteromedial placement, and large-fragment LPs for MTPFs caused significantly lower fracture gaps in the central articular after cyclic loading than small-fragment LPs.

Longitudinal CT-based finite element analyses provide objective fracture healing measures in an ovine tibia model.

Measuring the healing status of a bone fracture is important to determine the clinical care a patient receives. Implantable devices can directly and continuously assess the healing status of fracture fixation constructs, while subject-specific virtual biomechanical tests can noninvasively determine callus structural integrity at single time points. Despite their potential for objectification, both methods are not yet integrated into clinical practice with further evidence of their benefits required. This study correlated continuous data from an implantable sensor assessing healing status through implant load monitoring with computer tomography (CT) based longitudinal finite element (FE) simulations in a large animal model. Eight sheep were part of a previous preclinical study utilizing a tibial osteotomy model and equipped with such a sensor. Sensor signal was collected over several months, and CT scans were acquired at six interim time points. For each scan, two FE analyses were performed: a virtual torsional rigidity test of the bone and a model of the bone-implant construct with the sensor. The longitudinal simulation results were compared to the sensor data at corresponding time points and a cohort-specific empirical healing rule was employed. Healing status predicted by both in silico simulations correlated significantly with the sensor data at corresponding time points and correctly identified a delayed and a nonunion in the cohort. The methodology is readily translatable with the potential to be applied to further preclinical or clinical cohorts to find generalizable healing criteria. Virtual mechanical tests can objectively measure fracture healing progressing using longitudinal CT scans.

Combined vertical and external rotational force in plantarflexion position produces posterior pilon fracture: A preliminary cadaveric study.

BACKGROUND: Posterior pilon fracture is speculated to occur by a combination of rotation and axial load, which makes it different from rotational posterior malleolar fracture or pilon fracture, but is not validated in vitro. The aim of the current study is to investigate the injury mechanisms of posterior pilon fracture on cadaveric specimens. METHODS: Eighteen cadaveric specimens were mounted to a loading device to undergo solitary vertical loading, solitary external rotational loading, and combined vertical and external rotational loading until failure, in initial position of plantarflexion with or without varus. The fracture characteristics were documented for each specimen. RESULTS: Vertical loading force combined with external rotation force diversified the fracture types resulting in pilon fracture, tibial spiral fracture, rotational malleolar fracture, talar fracture or calcaneal fracture. Vertical violence combined with external rotational loading in position of 45° of plantarflexion and 0° of varus produced posterior pilon fracture in specimens No. 13 and 14. CONCLUSION: Combination of vertical and external rotational force in plantarflexion position on cadaveric specimens produce posterior pilon fracture.

Torsion constants and virtual mechanical tests are valid image-based surrogate measures of ovine fracture healing.

In large animal studies, the mechanical reintegration of the bone fragments is measured using postmortem physical testing, but these assessments can only be performed once, after sacrifice. Image-based virtual mechanical testing is an attractive alternative because it could be used to monitor healing longitudinally. However, the procedures and software required to perform finite element analysis (FEA) on subject-specific models for virtual mechanical testing can be time consuming and costly. Accordingly, the goal of this study was to determine whether a simpler image-based geometric measure-the torsion constant, sometimes known as polar moment of inertia-can be reliably used as a surrogate measure of bone healing in large animals. To achieve this, postmortem biomechanical testing and microCT scans were analyzed for a total of 33 operated and 20 intact ovine tibiae. An image-processing procedure to compute the attenuation-weighted torsion constant from the microCT scans was developed in MATLAB and this code has been made freely available. Linear regression analysis was performed between the postmortem biomechanical data, the results of virtual mechanical testing using FEA, and the torsion constants measured from the scans. The results showed that virtual mechanical testing is the most reliable surrogate measure of postmortem torsional rigidity, having strong correlations and high absolute agreement. However, when FEA is not practical, the torsion constant is a viable alternative surrogate measure that is moderately correlated with postmortem torsional rigidity and can be readily calculated.