Christoph Linhart

Purpose: Bone mineral density (BMD) is a key determinant of skeletal strength, relevant in many disciplines. Freezing is widely used to preserve cadaveric bone, but its effect on BMD remains controversal. This study assessed whether a vBMD is altered in frozen versus thawed state of human vertebral bodies measured by quantitative computed tomography (qCT). Materials and methods: Thirty-three human vertebrae (14 C7, 9 Th1, 10 Th2) were stored at − 20 °C. Trabecular and cortical vBMD were measured in the frozen state (− 15 to − 20 °C) using qCT with a calibration phantom. After thawing overnight at room temperature, identical scans were performed. Paired t-tests and Pearson correlation coefficients compared frozen and thawed values. Results: One trabecular specimen was excluded as an outlier. Mean trabecular volometeic bone mineral density (vBMD) was 154.68 mg Ca-HA/ml (frozen) vs. 148.93 mg Ca-HA/ml (thawed), mean difference − 5.74 mg Ca-HA/ml ( p = 0.164). Cortical vBMD was 219.56 mg Ca-HA/ml (frozen) vs. 219.90 mg Ca-HA/ml (thawed), mean difference 0.34 mg Ca-HA/ml ( p = 0.948). Correlations between frozen and thawed values were strong ( r = 0.89 trabecular; r = 0.94 cortical). Conclusion: A single freeze–thaw cycle at − 20 °C does not significantly alter cortical or trabecular vBMD in human vertebral bodies measured by qCT. These results support the measurement of BMD of frozen specimens, minimizing handling and avoiding unnecessary thawing in research and forensic settings.

Background: After unilateral total knee arthroplasty (TKA), patients place more weight on the nonsurgical limb than the surgical limb. The objective of this study was to determine the possibility of providing live biofeedback during early recovery of patients undergoing unilateral TKA and to determine the necessary sample size for future trials. Methods: Twenty patients with unilateral TKA were randomized into two groups: a feedback group and a control group. Inclusion criteria included no contralateral knee pain and aid-free walking before surgery. There were 8 patients in the feedback group and 10 in the control group. Compliance with the recommended training was 91%. The feedback group trained with an insole device for 15 min a day for 4 weeks, along with normal physiotherapy. The control group received normal physiotherapy only. Gait parameters were recorded on level ground at two and six weeks. The primary outcome was the percent loading rate. The secondary outcomes included gait speed, cadence, percent peak force, and pain. Results: Patients within the feedback group showed a small, non-significant trend toward a higher precent load rate at 6 weeks compared to the control group in level walking (p = 0.92). Conclusions: Our findings indicate that live biofeedback on a gait parameter, like percent load rate, can be provided by the mentioned system and may support immediate changes in gait parameters. The compliance of 91% with training and no reported adverse events indicates that the system was easy to use. Following TKA, there may be a potential exploratory use of mobile, real-time biofeedback to help address gait abnormalities and accelerate rehabilitation. This clinical trial was registered at clinicaltrials.gov (Identifier: NCT03673293) on 14 September 2018. This study was conducted in accordance with the Declaration of Helsinki and approved by the institutional review board of the University of Utah (IRB_00110935) on 10 September 2018.

Background: This institutional, register-based analysis aimed to evaluate the feasibility of using CT-based sacral Hounsfield units (HUs) for assessing bone density in pelvic fragility fractures and to explore their potential correlation with DEXA measurements and osteological laboratory diagnostics. Methods: Patients aged > 80 years, admitted between 2003 and 2019 with pelvic ring fractures, were analyzed in this retrospective single-center study. CT scans were evaluated according to the classification of fragility fractures of the pelvis (FFPs), which guided treatment decisions (conservative or surgical). The diagnosis of a fragility fracture was based on both fracture morphology and patient history, including the presence of low-energy trauma. Bone health was assessed using standardized laboratory diagnostics including serum calcium, phosphate, alkaline phosphatase, and 25(OH)-vitamin D, in addition to DEXA scans and CT-derived Hounsfield units. Vitamin D levels and bone density evaluations were analyzed to identify possible correlations among these factors and with fracture patterns. Results: A total of 456 patients (mean age 87.3 years, 79.6% female) were included. The CT-based FFP classification identified Type II as the most common fracture type (66.7%). Conservative treatment was the predominant approach (84.9%). Serum 25(OH)-vitamin D deficiency was observed in 62.7% of the patients, while osteopenia and osteoporosis were found in 34.3% and 46.5% of cases, respectively. HU values at S1 showed significant correlation with femoral neck T-scores, highlighting the utility of CT scans for bone density assessment. Conclusions: This study emphasizes the complementary roles of CT-derived HU values and DEXA T-scores in evaluating bone quality and fracture severity in geriatric patients with FFP. While DEXA remains the gold standard, CT imaging offers valuable early insights, supporting the timely initiation of osteoporosis therapy. Given the high prevalence of fragility fractures in this age group, early CT-based screening may facilitate earlier initiation of osteoporosis-specific therapy, including anabolic agents where indicated. Further research is needed to explore the relationships between vitamin D levels, bone density assessments, and fracture types.

Purpose: The surgical management of periprosthetic femoral fractures is particularly challenging in geriatric patients due to physiological limitations. The choice between open reduction and internal fixation (ORIF) and hip revision arthroplasty for treating Vancouver B2 and B3 fractures remains controversial. This study aims to contribute further evidence by analyzing the in-hospital outcomes in geriatric patients with Vancouver B2/3 fractures. Methods: This retrospective study analyzed 133 patients treated for Vancouver B2/3 fractures at a level I trauma center from 2017 to 2023. Data were collected on preclinical characteristics, comorbidities, Vancouver classification, surgery-related parameters, and postoperative outcomes for an age- and gender-matched analysis. A subgroup analysis was also conducted on patients classified as American Society of Anesthesiologists (ASA) class 3 and 4. Results: Among the 133 patients, 85 suffered Vancouver B2 fractures and 48 Vancouver B3 fractures. Age-and-gender-matched analysis revealed that ORIF was more commonly performed in patients with higher ASA grades. A subgroup analysis of ASA 3 and 4 patients and an age-and-gender-matched analysis showed that ORIF resulted in shorter operation times and less blood loss. No significant differences were found in mortality or complication rates. Conclusions: ORIF is associated with shorter operation times, less bleeding, and comparable in-hospital outcomes in treating Vancouver B2/3 fractures in higher-risk geriatric patients compared to revision arthroplasty. The retrospective design and small sample size in the ORIF group are limitations of the study. Further studies with functional evaluation are still required.

Background: Among the risk factors for nonunion are unchangeable patient factors such as the type of injury and comorbidities, and factors that can be influenced by the surgeon such as fracture treatment and the postoperative course. While there are numerous studies analyzing unchangeable factors, there is poor evidence for factors that can be affected by the physician. This raises the need to fill the existing knowledge gaps and lay the foundations for future prevention and in-depth treatment strategies. Therefore, the goal of this study was to illuminate knowledge about nonunion in general and uncover the possible reasons for their development; Methods: This was a retrospective analysis of 327 patients from 2015 to 2020 from a level I trauma center in Germany. Information about patient characteristics, comorbidities, alcohol and nicotine abuse, fracture classification, type of osteosynthesis, etc., was collected. Matched pair analysis was performed, and statistical testing performed specifically for atrophic long-bone nonunion; Results: The type of osteosynthesis significantly affected the development of nonunion, with plate osteosynthesis being a predictor for nonunion. The use of wire cerclage did not affect the development of nonunion, nor did the use of NSAIDs, smoking, alcohol, osteoporosis and BMI; Conclusion: Knowledge about predictors for nonunion and strategies to avoid them can benefit the medical care of patients, possibly preventing the development of nonunion.

Osteoporotic proximal femur fractures are on the rise due to demographic change. The most dominant surgical treatment option for per/subtrochanteric fractures is cephalomedullary nailing. As it has been shown to increase primary stability, cement augmentation has become increasingly popular in the treatment of osteoporotic per/subtrochanteric femur fractures. The ultimate goal is to achieve stable osteosynthesis, allowing for rapid full weight-bearing to reduce possible postoperative complications. In recent years, bioresorbable bone cements have been developed and are now mainly used to fill bone voids. The aim of this study was to evaluate the biomechanical stability as well as the micro-structural behaviour of bioresorbable bone cements compared to conventional polymethylmethacrylate (PMMA)-cements in a subtrochanteric femur fracture model. Biomechanical as well as micro-computed tomography morphology analysis revealed no significant differences in both bone cements, as they showed equal mechanical stability and tight interdigitation into the spongious bone of the femoral head. Given the positive risk/benefit ratio for bioresorbable bone cements, their utilisation should be evaluated in future clinical studies, making them a promising alternative to PMMA-bone cements.

Background: Gluteal muscle fatty atrophy (gMFA) might impair pelvic stability and negatively influence remobilization in patients with fragility fractures of the pelvis (FFP). This study aimed to investigate the association between gMFA and surgical indication in patients with FFP. Methods and materials: A retrospective analysis of 429 patients (age ≥80) diagnosed with FFP was performed. gMFA of the gluteus maximus, medius, and minimus was evaluated using a standard scoring system based on computer tomography images. Results: No significant difference was found in gMFA between genders or among FFP types. The severity of gMFA did not correlate with age. The severity of gMFA in the gluteus medius was significantly greater than in the gluteus maximus, whereas the most profound gMFA was found in the gluteus minimus. gMFA was significantly more severe in patients who underwent an operation than in conservatively treated patients with type-III FFP, and an independent correlation to surgical indication was found using logistic regression. Conclusion: Our findings imply that gMFA is an independent factor for surgical treatment in patients with type-III FFP. Besides focusing on the fracture pattern, the further evaluation of gMFA could be a feasible parameter for decision making toward either conservative or surgical treatment of type-III FFP.

Background: Early postoperative mobilization is essential for orthogeriatric patients. The prognostic nutritional index (PNI) is widely used to evaluate nutritional status. This study sought to investigate the predictive value of PNI for early postoperative mobility in patients with pertrochanteric femur fractures. Materials and methods: This study included 156 geriatric patients with pertrochanteric femur fractures treated with TFN-Advance™ (DePuy Synthes, Raynham, MA, USA). Mobility was evaluated on the third postoperative day and by discharge. Stepwise logistic regression analyses were performed to evaluate the association significance of PNI with postoperative mobility together with comorbidities. The optimal PNI cut-off value for mobility was analyzed using the receiver operating characteristic (ROC) curve. Results: Three days postoperatively, PNI was an independent predictor of mobility (OR: 1.14, 95% CI: 1.07–1.23, p < 0.01). By discharge, it was found that PNI (OR: 1.18, 95% CI: 1.08–1.30, p < 0.01) and dementia (OR: 0.17, 95% CI: 0.07–0.40, p < 0.001) were significant predictors. PNI correlated weakly with age (r = −0.27, p < 0.001). The PNI cut-off value for mobility on the third postoperative day was 38.1 (specificity = 78.5%, sensitivity = 63.6%). Conclusions: Our findings indicate that PNI is an independent predictor of early postoperative mobility in geriatric patients with pertrochanteric femur fractures treated with TFNA™.

BACKGROUND: Posterior instrumentation using pedicle screws and rods is the most commonly used technique for the treatment of thoracolumbar fractures of the spine. The procedure aims to restore the neurologic and biomechanical functions of the spine and allows for early mobilization and rapid reintegration into society. It is unclear whether the magnitude of correction has an effect on postoperative outcomes. OBJECTIVE: We aimed to determine whether the magnitude of sagittal angular correction during posterior instrumentation of the spine had an effect on postoperative quality of life, pain and function outcomes as measured using the EQ5D-3L and the Core Outcome Measures Index (COMI) instruments. We also aimed to quantify the correlation between EQ5D-3L and COMI scores. METHODS: We analyzed the pre- and postoperative radiographs of 52 patients who underwent percutaneous pedicle screw placement for thoracolumbar fractures, as well as their self-reported EQ5D-3L and COMI quality of life, pain and functional outcome scores. Regression models were constructed to estimate the effect that the magnitude of Cobb angle correction had on postoperative outcomes. We also estimated the correlation between EQ5D-3L and COMI scores. RESULTS: The median EQ5D-3L TTO score was 0.9 (range, -0.1 to 1). The median COMI score was 3.1 (range, 0 to 10). There was no significant effect of the magnitude of correction on EQ5d-3L TTO scores (p= 0.3379; R= 0.36) or on COMI scores (p= 0.3379; R= 0.15). Age and bone mineral density were not found to be significant predictors of outcome (p= 0.05). There was a strong correlation between the EQ5D-3L TTO and COMI scores (r=-0.62). CONCLUSION: The magnitude of Cobb angle correction during pedicle screw instrumentation of thoracolumbar fractures did not influence quality of life, pain or function outcomes. There was good correlation between EQ5D-3L TTO scores and COMI scores.

Purpose Osteoporosis-related proximal femur fractures continue to increase significantly due to demographic change. This study was designed to evaluate the biomechanical stability of two different fixation methods (cerclage vs. screw) for refixation of a trochanter minor fragment in the pertrochanteric fractures in cadaveric bones. Methods Artificial bones (n = 14) and human bones (n = 16) were treated with a DHS and the trochanter minor fragment was reduced by cerclage wiring or direct screw fixation. After preloading the simulated iliopsoas with 10 N, a tensile test was performed, ending with either a 70% loss of strength or avulsion of the fragment. The mean values of the avulsion force and the surface strain were recorded. Results All tensile tests showed no significant differences between refixation using a direct screw or wire cerclage, for both artificial bones and human specimens. Absolute values showed higher avulsion forces after direct screw fixation than refixation with a wire cerclage. The surface tension of specimens treated with direct screw fixation was lower than that of specimens treated with wire cerclage. An opposite effect was seen in artificial bones. Both effects were not statistically significant. Conclusion Based on the equal stability after lag screw placement compared to cerclage wiring, we promote the placement of a lag screw into the lesser trochanter fragment in pertrochanteric femur fractures when using a dynamic hip screw. Level of evidence Level III.