Exploration of bone metabolism status in the distal femur of mice at different growth stages.

The mouse femur, particularly the distal femur, is commonly utilized in orthopedic research. Despite its significance, little is known about the key events involved in the postnatal development of the distal femur. Therefore, investigating the development process of the mouse distal femur is of great importance. In this study, distal femurs of CD-1 mice aged 1, 2, 4, 6, and 8 weeks were examined. We found that the width and height of the distal femur continued to increase till the 4th week, followed with stabilization. Notably, the width to height ratio remained relatively consistent with age. Micro computed tomography analysis demonstrated gradual increases in bone volume/tissue volume, trabecular number, and trabecular thickness from 1 to 6 weeks, alongside a gradual decrease in trabecular separation. Histological analysis further indicated the appearance of the secondary ossification center at approximately 2 weeks, with ossification mostly completed by 4 weeks, leading to the formation of a prototype epiphyseal plate. Subsequently, the epiphyseal plate gradually narrowed at 6 and 8 weeks. Moreover, the thickness and maturity of the bone cortex surrounding the epiphyseal plate increased over time, reaching peak cortical bone density at 8 weeks. In conclusion, to enhance model stability and operational ease, we recommend constructing conventional mouse models of the distal femur between 4 and 8 weeks old.

Total knee arthroplasty and periprosthetic distal femoral fracture: looking beyond the osteoporosis to previous osteoporotic fracture.

Osteoporosis increases the risk of periprosthetic distal femoral fractures after TKA, especially in patients with a history of osteoporotic fractures. Therefore, careful assessment and proper treatment of osteoporosis need and the importance of taking osteoporotic medication needs to be recognized by the patients following primary TKA. PURPOSE: Osteoporosis is a risk factor for fractures, including those of the hip, vertebrae, and distal radius; however, the association between osteoporosis and periprosthetic fractures after total knee arthroplasty (TKA) has not been much investigated. Therefore, we aimed to investigate the association of the presence of systemic osteoporosis with periprosthetic fractures after TKA. METHODS: This study included 34 patients with periprosthetic fractures following primary TKA and 106 controls matched for age and sex. Bone mineral density was evaluated at the femoral neck, total hip, and lumbar spine using dual X-ray absorptiometry. Medical records were reviewed for age; sex; body mass index; smoking; rheumatoid arthritis, endocrine diseases, and cardiovascular diseases; history of glucocorticoid use; medication for osteoporosis; and history of previous osteoporotic fracture. In addition, anterior femoral notching after TKA was evaluated. Univariable and multivariable logistic regression analysis were used to determine factors associated with periprosthetic fracture. RESULTS: The prevalence of osteoporosis in the fracture group was higher than that in the control group (61.8% vs. 40.6%, p=0.045). The rate of medication for osteoporosis was significantly low in the fracture group (47.6 % vs 76.7%, p=0.026). History of previous osteoporotic fracture (odds ratio [OR], 9.1; p=0.015) and osteoporosis (OR, 3.6; p=0.013) were significant risk factors for periprosthetic fractures after TKA. Medication for osteoporosis could decrease the risk of periprosthetic fracture (OR 0.3; p=0.020). CONCLUSION: Osteoporosis is a major risk factor for periprosthetic distal femoral fractures after TKA. Therefore, careful assessment and proper treatment of osteoporosis need and the importance of taking osteoporotic medication needs to be recognized to the patients following primary TKA, especially in patients with a history of osteoporotic fracture. LEVEL OF EVIDENCE: Prognostic study, level III.

Morphological analysis of patellofemoral joint in haemophilic arthropathy: A case-control study.

INTRODUCTION: Knees affected by haemophilic arthropathy exhibit distinct differences in both bone morphology and soft tissue behaviour. This study aims to analyse the morphological characteristics of the distal femur and patellofemoral joint in patients with haemophilia in comparison to normal healthy population. MATERIAL AND METHODS: Study was conducted as pair-matched case-control study with 43 individuals in both the haemophilia group and the control group. Patellar luxation, patellar tilt (PT), length of the patella in both axis (pAP, pML), depth and angle of trochlear sulcus (SD, SA), lateral trochlear inclination (LTI), medial and lateral femoral facet length (mFL, LFL), intercondylar depth (ID), transepicondylar axis (TEA) and lateral condyle length (LCL) were assessed on knee MRI. Correlation between Pettersson score and measured variables were also analysed. RESULTS: PT was medial sided in 10 (23.2%) cases in haemophilic group. Mean values of pAP, pML, PT were significantly lower in haemophilia group (p < .001, p: .007, p = .001 respectively). There were no significant changes in SA (p = .628), SD (p = .340), LTI (p = .685), LFL (p = .241) and MFC-LFC (p = .770) whilst mFL was significantly longer in haemophilia group (p = .009). ID (p < .001), TEA (p = .007) and LCL (p = .001) were all shorter in haemophilia group. Pettersson score was inversely correlated with pAP, pML, ID, TEA, LCL, pML/SA and ID/LCL. CONCLUSION: Morphological changes in haemophilic arthropathy involve a smaller and medially-tilted patella, narrowed lateral condyle and transepicondylar axis, combined with reduced intercondylar depth. These alterations must keep in mind especially in pre- and intraoperative assessments for arthroplasty procedures.

External fixator versus elastic stable intramedullary nail for treatment of metaphyseal-diaphyseal junction fractures of the pediatric distal femur: a case-control study.

BACKGROUND: Several methods have been used for the treatment of pediatric distal femoral fractures, such as elastic stable intramedullary nail (ESIN), external fixator (EF) and plate osteosynthesis, but there has been no consensus about the optimal method. The purpose of this study was to compare the clinical outcome between EF and ESIN techniques used in metaphyseal-diaphyseal junction (MDJ) fractures of the pediatric distal femur. METHODS: We retrospectively analyzed operatively treated MDJ fractures of pediatric distal femur between January 2015 and January 2022. Patient charts were reviewed for demographics, injury and data of radiography. All of the patients were divided into EF and ESIN groups according to the operation techniques. Malalignment was defined as more than 5 degrees of angular deformity in either plane. Clinical outcomes were measured by Flynn scoring system. RESULTS: Thirty-eight patients were included in this study, among which, 23 were treated with EF, and 15 with ESIN. The mean follow-up time was 18 months (12-24 months). At the final follow-up, all of the fractures were healed. Although there were no statistical differences between the two groups in demographic data, length of stay, estimated blood loss (EBL), rate of open reduction, time to fracture healing and Flynn score, the EF was superior to ESIN in operative time, fluoroscopic exposure and time to partial weight-bearing. The EF group had a significantly higher rate of skin irritation, while the ESIN had a significantly higher rate of malalignment. CONCLUSION: EF and ESIN are both effective methods in the treatment of MDJ fractures of the pediatric distal femur. ESIN is associated with lower rates of skin irritation. However, EF technique has the advantages of shorter operative time, reduced fluoroscopic exposure, and shorter time to partial weight-bearing, as well as lower incidence of malalignment. LEVEL OF EVIDENCE: Level III.

Decreased femoral trochlea axial orientation corrected by derotational distal femur osteotomy in patients with patellar dislocation yields satisfactory outcomes.

PURPOSE: The femoral trochlea axial orientation has been shown to be a better predictor of patellar dislocation than the femoral anteversion angle. However, no study has investigated the importance of the femoral trochlea axial orientation in the surgical treatment of patellar dislocation. It is aimed to explore the pathological threshold of the femoral trochlea axial orientation and its guiding implications for surgical interventions in the study. METHODS: Sixty-four patients with patellar dislocation and 64 controls were included for measurement of the femoral trochlea axial orientation. The ability to predict the patellar dislocation and the pathologic threshold of the femoral trochlea axial orientation were evaluated using the receiver operating characteristic curve. One hundred patients with medial patellofemoral ligament reconstruction and 25 patients with derotational distal femur osteotomy were divided into two groups based on the femoral trochlea axial orientation cut-off value and their postoperative knee functions, and patellar tilt angles were compared. RESULTS: There were significant differences in the femoral trochlea axial orientation (60.8 ± 7.9 vs. 67.8 ± 4.6, p < 0.05) between patients with patellar dislocation and the normal population. The sensitivity and specificity of the femoral trochlea axial orientation were 0.641 and 0.813, respectively, at the femoral trochlea axial orientation smaller than 63.8°. Amongst patients having had isolated medial patellofemoral ligament reconstruction with decreased femoral trochlea axial orientation, knee function was poorer after surgery. The prognosis of patients with the femoral trochlea axial orientation correction in derotational distal femur osteotomy was better than that for patients without correction. CONCLUSIONS: The femoral trochlea axial orientation had good predictive efficiency for patellar dislocation. Isolated medial patellofemoral ligament reconstruction is not sufficiently effective for patients with patellar dislocation and decreased femoral trochlea axial orientation. Patients with a decreased femoral trochlea axial orientation can have better surgical outcomes after correction by derotational distal femur osteotomy. LEVEL OF EVIDENCE: Level III.

Far cortical locking constructs for fixation of distal femur fractures in an Asian population: A prospective observational study.

BACKGROUND: The stiffness of locked plates suppresses healing process, prompting the introduction of far cortical locking to address this issue. This study aimed to demonstrate the clinical efficacy of far cortical locking constructs in treating distal femoral fractures in an Asian population. METHODS: This multicenter prospective observational study was conducted at four university hospitals between February 2018 and February 2021. Demographic data, the presence of metaphyseal comminution, and surgical fixation details were recorded. Clinical outcomes, including single-leg standing, EQ-5D, and EQ-VAS scores, and radiologic outcomes, including the RUST score of each cortex, were evaluated and compared according to the presence of metaphyseal comminution. RESULTS: There were 37 patients (14 men and 23 women) with a mean age of 67.3 ± 11.8 years. Twenty-two patients had metaphyseal comminution (59%), and 15 presented simple fractures in metaphyseal areas. Four patients (13%) could stand on one leg >10s at 6 weeks, and 24 patients (92%) at 1 year. EQ-5D increased from 0.022 ± 0.388 to 0.692 ± 0.347, and the mean EQ-VAS 51.1 ± 13.1 to 74.1 ± 24.1 between discharge (n = 37) and post-operative 1 year (n = 33), respectively. RUST score presented increment for time, from 6.2 ± 1.8 at 6 week to 11.6 ± 1.1 at 1 year. Radiological healing demonstrated rapid increase from week 6 (16/28, 43%) to month 3 (27/31, 87%), with no obvious increase was observed in 6 months (23/26, 89%) or 12 months (25/28, 89%). Simple metaphyseal fractures presented significantly higher RUST scores at 6 weeks and 3 months, but there was no difference in RUST scores at 6 months or 1 year according to metaphyseal comminution. CONCLUSIONS: Plate constructs with far cortical locking screws provided safe and effective fixation for distal femoral fractures, with consistent radiological and clinical results, regardless of metaphyseal comminution.

Geriatric distal femoral fractures: post-operative complications and nine-year mortality-a retrospective analysis of two tertiary trauma centres.

PURPOSE: This study aimed to estimate the mortality at various post-operative intervals and explore influential variables for these outcomes in elderly patients with distal femur fractures (DFF). METHODS: A retrospective observational study was conducted across two tertiary care institutions, between 2014 and 2020. The primary outcomes were mortality rates at 30-day, six month, and one year post-surgery. Secondary outcomes included 1-year readmission and reintervention rates along with their correlated complications. RESULTS: A total of 37 DFF in 35 patients was analyzed; average age was 83.6 years (range, 65-98 years). The overall mortality rate at a maximum follow-up of 8.8 years was 74% (26/35 patients). The median survival time was 3.2 years and the survival probability at five years was 27% (95% confidence interval [CI], 13 to 43%). Mortality rates at 30 days, six months, and one year after surgery were 8.6% (3 patients), 23% (8 patients), and 34% (12 patients), respectively. Overall mortality rate was 64% (15/24 patients) for native distal femur fractures, and 92% (13/14 patients) for periprosthetic fractures (p = 0.109). Patients older than 85 years and male gender were identified as risk factors for mortality within the first year post-operatively. CONCLUSION: Elderly fractures have a high mortality at eight years of follow-up. Mortality at one year was much higher than in other studies of the same nature. We did not find statistically significant differences when comparing native bone fractures with periprosthetic fractures. Factors that impact mortality were being a man, advanced age, elevated index comorbidity, and dementia. There is no relationship between the time to be taken to the surgical procedure and mortality results.

Cortical bone thickness on preoperative CT scans as predictor of bone quality in distal femur fractures: a retrospective study in Caucasians.

AIM: Distal femur fractures (DFF) are rare, but associated with high complication rates and mortality, particularly in patients with osteoporosis. To improve preoperative assessment, we analyzed if cortical bone thickness on CT and AP radiographs is associated with clinical parameters of bone quality. METHODS: Retrospective single-center study of adult patients presenting at a level-one trauma center, with a DFF between 2011 and 2020. Clinical parameters for bone quality, such as age, sex, body mass index (BMI), energy impact level of trauma, and known history of osteoporosis, were assessed. Mean cortical bone thickness (CBTavg) on AP radiograph was determined using a previously published method. Cortical thickness on CT scan was measured at 8 and 14 cm proximal to the articular surface of the lateral condyle. RESULTS: 71 patients (46 females) between 20 and 100 years were included in the study. Cortical thickness determined by CT correlated significantly with CBTavg measurements on AP radiograph (Spearman r = 0.62 to 0.80; p < 0.001). Cortical thickness was inversely correlated with age (Spearman r = - 0.341 to - 0.466; p < 0.001) and significantly associated with trauma impact level and history of osteoporosis (p = < 0.001). The CT-based values showed a stronger correlation with the clinical parameters than those determined by AP X-ray. CONCLUSION: Our results showed that cortical thickness of the distal femur correlates with clinical parameters of bone quality and is therefore an excellent tool for assessing what surgical care should be provided. Interestingly, our findings indicate that cortical thickness on CT is more strongly correlated with clinical data than AP radiograph measurements.

Risk of reverse golf club deformity with medial plating of distal femur fracture.

INTRODUCTION: This study described a deformity induced by medial plating of supracondylar distal femur fractures using plates that are precontoured for other anatomic locations. MATERIALS AND METHODS: OTA/AO 33A fractures were created in 12 sawbone femurs and fixed with either a proximal humerus locking plate (PH), an ipsilateral lateral tibial plateau plate (LTP), or an ipsilateral medial distal tibial plate (MDT). A motion capture system measured changes in length and rotation of the distal femur as the plate was applied. Each plate underwent four trials and the mean and standard deviation (SD) for each measurement was reported. An analysis of variance with post hoc Tukey test compared malreduction measures between plate types. RESULTS: All plates consistently created a varus deformity. There was lateral lengthening with a compensatory medial shortening and an increase in the lateral distal femoral angle. The distal fracture fragment was laterally translated, and internally rotated. The PH plate had significantly greater lateral length (27.39 mm SD 4.78, p = 0.007), shorter medial length (13.57 mm SD 4.99, p = 0.028), greater lateral translation (28.82 mm SD 5.70, p = 0.010) and greater widening of the lateral distal femoral angle (28.54° SD 4.98, p < 0.001) than the LTP and MDT plates. The MDT plate had significantly greater angulation anteriorly (8.40° SD 1.07, p < 0.001) and laterally (7.63° SD 3.10, p = 0.002) than the PH and LTP plates. There was no significant difference between plates in internal rotation (PH: 3.07° SD 2.79; LTP: 2.05° SD 1.05; MDT 3.81° SD 3.56; p = 0.659). CONCLUSION: When dual plating supracondylar distal femur fractures, poor plate positioning and a mismatch between plate contour and the slope of the medial distal femur can lead to varus angulation, internal rotation, and lateral translation or a "reverse golf club deformity". After comparing three types of precontoured plates, the authors recommend initial evaluation of the ipsilateral proximal tibial plate when placing a plate along the medial distal femur. LEVEL OF EVIDENCE: IV.

Comparative study of retrograde intramedullary nailing versus locking extramedullary plating in complete articular fractures with metaphyseal comminution of the distal femur.

INTRODUCTION: Fractures of the distal femur with metaphyseal comminution and complete intra-articular involvement (AO/OTA classifications 33C2 and 33C3) present challenges for reduction and fixation. However, an optimal fixation method remains unknown. This study aimed to compare the clinical and radiographic outcomes of locking extramedullary plating (LEP) and retrograde intramedullary nailing (RIN) for complete distal femoral intra-articular fractures with metaphyseal comminution. MATERIALS AND METHODS: Between January 2016 and May 2022, 80 patients (45 men and 35 women; average age, 56.7 years) diagnosed with AO/OTA 33C2 and 33C3 were treated with either LEP or RIN and followed up for at least one year. Post-operative evaluations included radiographic assessments of bone union rate, timing, and alignment. Clinically, the knee joint range of motion (ROM), lower extremity functional scale (LEFS), and Kellgren and Lawrence (KL) grade were analyzed. The complications were also compared. RESULTS: 36 underwent LEP and 44 underwent RIN. Bone union was observed in 69.4% and 63.6% of the patients in the LEP and RIN groups, respectively (p = 0.64). The average union time was 6.9 months for the LEP group and 6.6 months for the RIN group (p = 0.51). A tendency toward varus deformity was observed in the RIN group, although the difference was not statistically significant. No significant differences were observed in knee ROM, LEFS, or KL grade. Complications included non-union (33.8%; RIN, 11; LEP, 16), varus deformity (5%; RIN, 4; LEP, 0), infection (1.3%; RIN, 0; LEP, 1), heterotrophic ossification (1.3%; RIN, 0; LEP, 1), and wound dehiscence (2.5%; RIN, 2; LEP, 0). CONCLUSIONS: The surgical fixation methods, RIN and LEP, for complete distal femoral intra-articular fractures with metaphyseal comminution showed similar clinical and radiological outcomes. However, regardless of the type of fixation device used, there was a reduced rate of bone union owing to high energy and a less favorable prognosis.

Does the type of medial plate fixation matter for supplemental fixation of distal femur fractures manage with a lateral pre-contoured locked plate? A Biomechanical study.

INTRODUCTION: Fixation of distal femur fractures with a lateral pre-contoured locking plate provides stable fixation and is the standard treatment in most cases, allowing early range of motion with a high rate of union. However, in situations, the stability achieved with the lateral plate alone may be insufficient, predisposing to fixation failure. The objective of the study was to compare, in synthetic bone models, the biomechanical behaviour of the fixation with a distal femur lateral pre-contoured locking plate solely and associated with a 3.5 mm proximal humeral locking plate applied upside down or a 4.5 mm helical locking compression plate on the medial side. MATERIAL AND METHODS: A total of 15 solid synthetic left femur samples were used. A metaphysical defect at the level of the medial cortex was simulated. The samples were randomly distributed into three groups equally. All groups received a 4.5/5.0 mm single lateral 9-hole distal femur lateral pre-contoured locking plate. Group 1 had no supplementary plate. Group 2 received a supplementary 6-hole 3.5 mm proximal humeral locking plate and Group 3 received a supplementary 4.5/5.0 mm helical 14-hole narrow locking compression plate. RESULTS: Both supplementary plate types used in groups 2 and 3 contributed to increase the apparent stiffness of the construct, but pairwise comparison showed statically significant difference only between group 1 and 3. No significant difference was observed between groups 2 and 3. CONCLUSION: Both supplementary plates might be considered for improving the fixation in distal femur fracture in selected cases.

Titanium versus stainless steel alloy bridge plates for distal femur fractures: Does callus form earlier with titanium?

INTRODUCTION: Distal femur fractures account for 3-6% of all femur fractures. Internal fixation of most distal femur fractures with an anatomic lateral locking plate should permit some motion at the metaphyseal portion of the fracture when secondary bone healing is planned by the operating surgeon. While several studies have been performed evaluating union rates for distal femur fractures with stainless steel and titanium plates, the timing of callus formation between stainless steel and titanium implants used as bridge plates for distal femur fractures (AO/OTA 33-A and -C) has been investigated to a lesser extent. We hypothesize that callus will be visualized earlier with post-operative radiographs with titanium versus stainless steel bridge plates. METHODS: We retrospectively reviewed a consecutive cohort of patients over 18 years of age with acute AO/OTA 33-A and 33-C fracture patterns treated with an isolated stainless steel or titanium lateral bridge plate within 4 weeks of injury by a single fellowship-trained orthopedic trauma surgeon from 2011 to 2020 at one academic Level 1 trauma center. An independent, fellowship-trained orthopedic trauma attending surgeon reviewed anterior-posterior (AP) and lateral radiographs from every available post-operative clinic visit and graded them using the Modified Radiographic Score for Tibia (mRUST). RESULTS: Twenty-five subjects were included in the study with 10 with stainless steel and 15 with titanium plates. There were no significant differences in demographics between both groups, including age, sex, BMI, injury classification, open versus closed, mechanism, and laterality. Statistically significant increased mRUST scores, indicating increased callus formation, were seen on 12-week radiographs (8.4 vs. 11.9, p = 0.02) when titanium bridge plates were used. There were no statistically significant differences in mRUST scores at 6 or 24-weeks, but scores in the titanium group were higher in at every timepoint. DISCUSSION: In conclusion, we observed greater callus formation at 12 weeks after internal fixation of 33-A and 33-C distal femur fractures treated with titanium locked lateral distal femoral bridge plates compared to stainless steel plates. Our data suggest that titanium metallurgy may have quicker callus formation compared to stainless steel if an isolated, lateral locked bridge plate is chosen for distal femur fracture fixation.

Distal femur fractures in elderly treated with internal fixation or distal femoral replacement - retrospective cohort study on 75 patients assessing functional outcomes, reoperations, and mortality.

PURPOSE: This cohort study aimed to describe the functional outcomes, complications, and mortality of patients over 65 with acute distal femur fractures treated with open reduction and internal fixation (ORIF) or distal femoral replacement (DFR). METHODS: We retrospectively analyzed all patients older than 65, operated consecutively for a distal femur fracture treated with ORIF or DFR. We included 75 patients (9 33A, 5 33B, and 61 33C AO/OTA fractures), 55 treated with ORIF, and 20 with DFR. We used Parker's mobility index (PMI) to assess functional outcomes at 1, 3, and 12 months and study closure. We analyzed complications, reoperations, and mortality at 30 days, one year, and at the end of the study. RESULTS: The PMI was significantly higher in the DFR group at months 1 (p = 0.023) and 3 (p = 0.032). We found no significant differences between cohorts at one year and the end of follow-up. Postoperative complications were significantly more frequent in the ORIF group (38.10% vs. 10%, p = 0.022). Reoperations were similar in both cohorts (p = 0.98). Mortality at one month was 4% and 20% at one year, and at the end of follow-up, there were no significant differences between groups. CONCLUSION: The outcomes of this study suggest that DFR offers a faster functional recovery with lower complication rates than those treated with ORIF. Additionally, both options have similar reoperation and mortality rates. Appropriately designed studies are needed to define the best treatment strategy for this type of patient.

Nonvascularized fibular graft with locking screw fixation for metaphyseal bone loss of distal femur: biomechanical assessment validated by a clinical case series.

BACKGROUND: The optimal modality to surgically treat significant bone loss of distal femur remains inconclusive. The objectives of the present study were to assess the mechanical performance of nonvascularized fibular graft (NVFG) with locking screw fixation in distal femur fixation construct by finite element analysis and to retrospectively describe the outcomes of the present technique in clinical cases. METHODS: Four constructs which the fractured femur was stabilized by LCP-DF alone, dual plating, LCP-DF combined with NVFG, and LCP-DF combined with NVFG (LCP-DF-NVFG-S) with locking screw were assessed the biomechanical performance under physiological loads. For the clinical case series, 12 patients with open intercondylar fracture with metaphyseal bone loss of distal femur were operated by LCP-DF-NVFG-S. The collected data included fracture consolidation, length of NVFG, perioperative complications and objective clinical results. RESULTS: LCP-DF-NVFG-S demonstrated lower implant equivalent von Mises stress (EQV) stress and better fracture stability than other constructs. A locking screw presented its essence in maintaining the NVFG in the required position and subsequently enhancing the fracture stability. In regard to the clinical series, all fractures were consolidated with an average duration of 27.8 weeks (range 20-32). An average NVFG length was 7.8 cm (range 6-12). No perioperative complication was demonstrated. By the Knee Society score, 1 was considered to be excellent, 9 to be good and 2 to be poor. CONCLUSION: Based on the results of mechanical assessment and case series, LCP-DF-NVFG-S can be an effective technique in the management of metaphyseal bone loss of distal femur.

High revision rates and mortality after distal femoral replacement for periprosthetic distal femoral fractures: analysis from the German Arthroplasty Registry (EPRD).

PURPOSE: This study was initiated to analyze the outcome after distal femoral replacement (DFR) for periprosthetic distal femoral fractures (PDFF). METHODS: Data from the German Arthroplasty Registry (EPRD) were analyzed. A total of 626 patients could be identified with a DFR for PDFF. Mean age was 78.8 years, and 84.2% were female. Revisions and mortality were analyzed and compared with patient groups with a similar procedure (revision total knee arthroplasty) or similar general condition (fracture total hip arthroplasty, hip hemiarthroplasty). Matched-pair-analyses were performed. RESULTS: Within one year after surgery, 13.2% of the patients had died and further 9.4% were revised. Within four years, 32.7% had died and 19.7% were revised. Revisions were nearly twice as high as in the comparison groups. Periprosthetic infection (PJI) was the most frequent cause for revision, resulting in a PJI rate of 12.8%, which was lower in the comparison groups. Mortality after DFR was as similar high as after fracture hip arthroplasty. CONCLUSION: PDFF are a serious injury, and the necessary surgical treatment has a high risk of complications. Every third patient after DFR for PDFF had died and every fifth patient needed revision within 4 years after surgery. Efforts should be undertaken to provide optimal treatment to these high-risk patients to reduce unfavorable outcomes. LEVEL OF EVIDENCE: III. REGISTRATION OF CLINICAL TRIALS: As this is a registry-derived study of data of the German Arthroplasty Registry (EPRD), no registration was performed.

Rates of interlock screw back-out are high with the retrograde femoral nailing advanced system for distal femur fractures.

PURPOSE: The retrograde femoral nailing advanced (RFNA) system (DePuy synthes) is a commonly used implant for the fixation of low distal femur and periprosthetic fractures. There is concern that the rate of distal interlock screw back-out may be higher for the RFNA compared to other nails (ON). The purpose of this study was to evaluate the incidence of interlock screw back-out and associated screw removal for RFNA versus ON, along with associated risk factors. METHODS: A retrospective comparative study of patients who underwent retrograde nailing for a distal femur fracture at an academic level one trauma center was performed. The incidence of distal interlock screw back-out and need for screw removal were compared for RFNA versus a propensity score matched cohort who received other nails. RESULTS: One hundred and ten patients underwent retrograde nailing with the RFNA for a distal femur fracture from 2015 to 2022 (average age: 66, BMI: 32, 52.7% smokers, 54.5% female, 61.8%). There was a significantly higher rate of interlock back-out in the RFNA group compared to the ON (27 patients, 24.5% vs 12 patients, 10.9%, p = 0.01), which occurred 6.3 weeks postoperatively. Screw removal rates for back-out were not significantly different for the RFNA group versus ON (8 patients, 7.3% vs 3 patients, 2.7%, p = 0.12). CONCLUSION: In this retrospective comparative study of distal femur fractures treated with retrograde nailing, the RFNA implant was associated with an increased risk of distal interlock screw back-out compared to other nails.

Total femoral spanning for distal femur "fragility" fractures utilising nail-plate fixation "short-term experience of a district general hospital".

PURPOSE: Our primary objective was to investigate the time to radiological union following linked nail-plate fixation of distal femur "fragility" fractures. Secondary objectives were to evaluate all-cause reoperations, 90-day mortality, rate of blood transfusion and the impact on quality of life. METHODS: In this retrospective study of all adults (≥ 65 years) with native or periprosthetic distal femur fragility fractures, underwent a linked nail-plate fixation, data were retrieved on fracture classifications, clinical frailty score, blood transfusion, length of hospital stay, 90-day mortality, time to radiological union, overall complication rates and EuroQoL-5D. RESULTS: In total, 18 out of 23 patients completed sequential follow-up. Radiological union was observed in 14 patients (median 143 days; range 42-414). Three patients underwent reoperations. There were no implant failures or a subsequent periprosthetic fractures. Ninety-day mortality was 17.4%. Eighteen patients required blood transfusion. The QoL was significantly lower after index surgery (0.875 vs. 0.684; p < 0.01). CONCLUSION: Based on our observation, with short-term follow-up, the linked nail-plate yields optimal stability to allow immediate weight bearing, in a cohort with moderate frailty. It is reproducible, with variable radiological union rates. The concept of "total femoral spanning" reduces the risk of subsequent periprosthetic fractures. The additional intervention has increased the rates of allogenic blood transfusion. There is significant impact on overall QoL, with almost 50% being more dependent in self-care.

Retrograde intramedullary nailing with supplemental plate and lag screws allows early weight bearing following distal end-segment femur fractures (AO/OTA 33) in a low-resource setting.

PURPOSE: To underline the feasibility of achieving early weight bearing in patients with distal end-segment femur fractures (AO/OTA 33) treated with retrograde intramedullary nailing and supplemental plate or lag screws in the absence of C-arm. METHODS: 41 distal end-segment femur fractures (DFFs) included in the study were treated with SIGN nails with or without a side plate in a center that lacked intraoperative fluoroscopy and fracture table. A medial or lateral para-patellar incision was used for fracture reduction, nail insertion and side plate placement. Follow-ups were done at six weeks, 12 weeks, and six months post-operatively. RESULTS: Distal end-segment fractures constituted 13.2% of all femur fractures treated. The patients' mean age and range were 49.6 and 23-83 years respectively. They were mostly injured in road traffic accidents. 27 were daily-income earners. By the 12th week post-operatively, 82.1% of them could flex their knee beyond 90°, all of them could bear weight fully, and 71.8% could squat & smile. CONCLUSION: The study highlighted the procedure for retrograde nailing of DFFs in a setting without the requisite facilities for minimally-invasive surgeries. The findings demonstrated the feasibility of achieving an expedited weight bearing for the predominantly daily-income-earning victims to ensure early return to work and poverty reduction. While the small sample size is a limitation, the study does provide information that could serve as a basis for future randomized controlled trials in low-resource settings.

The Impact of Delayed Osteosynthesis of Bone Healing in Patients with Extra-articular Distal Femoral Fracture.

Background: In extra-articular distal femoral fractures (EDFFs), nonunion is a serious complication that occurs rarely. In this study, we examined how longer preservation of initial fracture hematoma by delaying the osteosynthesis (OS) affects the fracture union. Methods: In a retrospective cohort study, 98 EDFF patients were included. The OS was done within 2 days of injury in 50 patients (early OS group) and after 2 days of injury in 48 patients (late OS group). Time to callus formation and fracture union, bleeding amount, surgical duration, pain, knee range of motion, knee function, and postoperative complications, including the nonunion, knee deformity, infection, and revision, were compared between the 2 groups. Statistical analyses were done with SPSS. A comparison of the mean between the 2 groups was made with an independent t test or its nonparametric counterpart. A comparison of categorical variables between the 2 groups was made using a chi-square or the Fisher's exact test. P ˂ 0.05 was considered statistically significant. Results: The mean time to callus formation was 47.1 ± 17.3 days in the early OS group and 46.9 ± 19.7 in the late OS group (P = 0.950). The mean time to fracture union was 114.9 ± 21 in the early OS group and 117.4 ± 28.8 days in the late OS group (P = 0.630). The mean operation time and bleeding amount between the 2 groups did not differ significantly (P = 0.230 and P = 0.340, respectively). The knee range of motion, pain, and function were not notably different (P = 0.620, P = 0.790, and P = 0.770, respectively). Nonunion occurred in 3 patients of early OS and 2 patients of the late OS group. Other complications were also comparable in the 2 study groups. Conclusion: Delayed OA in EDFF patients has no significant effect on bone healing and fracture union. Future standard studies are required to confirm these results.

Functional and Oncological Outcome of Patients with Distal Femoral Osteosarcoma Managed by Limb Salvage Using Modular Endoprosthesis.

BACKGROUND: The aim of the study was to assess the functional and oncological outcomes of patients with distal femoral osteosarcoma managed by limb salvage using modular endoprosthesis as well as to assess related complications. PATIENTS AND METHODS: A total of 82 patients were included in our study. Functional outcome was assessed using MSTS score and knee range of motion. Oncological outcome was assessed regarding local recurrence, chest metastasis, and patient survivorship. Complications were classified according to Henderson et al. RESULTS: The mean MSTS score was 26.21 (87.4%) (range 8-30 points) with 70.7% of patients having more than 90° of flexion. The incidence of local recurrence was 3.7% (3 patients), while the incidence of chest metastasis was 14.6% (12 patients). Aseptic loosening (type 2 failure) was the commonest complication (19.5%), followed by infection (15.9%). The 5- and 10-year survivorships of the limb were 98.8%, while the 5- and 10-year survivorships of the prosthesis were 67.7% and 52.4%, respectively. CONCLUSION: This study showed that patients with osteosarcoma distal femur who are treated by chemotherapy and limb salvage have an excellent long-term prognosis in terms of patient as well as limb survivorship. The use of modular endoprosthesis in these patients offer an acceptable function, with two-thirds of the patients retaining their prosthesis after 5 years and more than half retaining them after 10 years.