Stress-vs-time signals allow the prediction of structurally catastrophic events during fracturing of immature cartilage and predetermine the biomechanical, biochemical, and structural impairment

Objective Trauma-associated cartilage fractures occur in children and adolescents with clinically significant incidence. Several studies investigated biomechanical injury by compressive forces but the injury-related stress has not been investigated extensively. In this study, we hypothesized that the biomechanical stress occurring during compressive injury predetermines the biomechanical, biochemical, and structural consequences. We specifically investigated whether the stress-vs-time signal correlated with the injurious damage and may allow prediction of cartilage matrix fracturing. Methods Superficial and deeper zones disks (SZDs, DZDs; immature bovine cartilage) were biomechanically characterized, injured (50% compression, 100%/s strain-rate), and re-characterized. Correlations of the quantified functional, biochemical and histological damage with biomechanical parameters were zonally investigated. Results Injured SZDs exhibited decreased dynamic stiffness (by 93.04 ± 1.72%), unresolvable equilibrium moduli, structural damage (2.0 ± 0.5 on a 5-point-damage-scale), and 1.78-fold increased sGAG loss. DZDs remained intact. Measured stress-vs-time-curves during injury displayed 4 distinct shapes, which correlated with histological damage (p < 0.001), loss of dynamic stiffness and sGAG (p < 0.05). Damage prediction in a blinded experiment using stress-vs-time grades was 100%-correct and sensitive to differentiate single/complex matrix disruptions. Correlations of the dissipated energy and maximum stress rise with the extent of biomechanical and biochemical damage reached significance when SZDs and DZDs were analyzed as zonal composites but not separately. Conclusions The biomechanical stress that occurs during compressive injury predetermines the biomechanical, biochemical, and structural consequences and, thus, the structural and functional damage during cartilage fracturing. A novel biomechanical method based on the interpretation of compressive yielding allows the accurate prediction of the extent of structural damage.National Institutes of Health (U.S.) (Grant R01-AR45779)Deutsche Forschungsgemeinschaft (Grant RO2511/1-1)Deutsche Forschungsgemeinschaft (Grant RO2511/2-1)Germany. Federal Ministry of Education and Research (Grant 01KQ0902B TP2

Does fixed-angle plate osteosynthesis solve the problems of a fractured proximal humerus?: A prospective series of 87 patients

Background and purpose There is considerable controversy about the treatment of complex, displaced proximal humeral fractures. Various types of head-preserving osteosynthesis have been suggested. This prospective case series was designed to evaluate the perioperative and early postoperative complications associated with fixed-angle implants and to record outcome after bone healing

Inter- and intraobserver reliability of the MTM-classification for proximal humeral fractures: A prospective study

<p>Abstract</p> <p>Background</p> <p>A precise modular topographic-morphological (MTM) classification for proximal humeral fractures may address current classification problems. The classification was developed to evaluate whether a very detailed classification exceeding the analysis of fractured parts may be a valuable tool.</p> <p>Methods</p> <p>Three observers classified plain radiographs of 22 fractures using both a simple version (fracture displacement, number of parts) and an extensive version (individual topographic fracture type and morphology) of the MTM classification. Kappa-statistics were used to determine reliability.</p> <p>Results</p> <p>An acceptable reliability was found for the simple version classifying fracture displacement and fractured main parts. Fair interobserver agreement was found for the extensive version with individual topographic fracture type and morphology.</p> <p>Conclusion</p> <p>Although the MTM-classification covers a wide spectrum of fracture types, our results indicate that the precise topographic and morphological description is not delivering reproducible results. Therefore, simplicity in fracture classification may be more useful than extensive approaches, which are not adequately reliable to address current classification problems.</p

Complication rates and outcomes stratified by treatment modalities in proximal humeral fractures : a systematic literature review from 1970-2009

BACKGROUND: The optimal treatment of complex, displaced proximal humeral fractures is controversial. A systematic literature review of the time period from 1970 to 2009 was conducted. The purpose was to evaluate the clinical success and complications of the available treatment modalities to determine specific treatment recommendations for the different fracture patterns. METHODS: The databases (PubMed/EMBASE) were searched for the time period (01/1970–09/2009). Study quality, treatment modalities, classification, outcome scores and complications of 200 publications including 9377 patients were analyzed. Interventions were compared by analysis of variance with subsequent Tukey’s-test. Complication rates among methods were compared by using Pearson’s-chi-square-test and pairwise comparisons using Fisher’s-two-tailed-exact-test. RESULTS: Hemiarthroplasty, angle-stable plate and non-operative treatment were used for 63% of the follow-up-patients. For 3- and 4-part fractures, patients with hemiarthroplasty [3-Part: 56.4 (lower/upper 95% confidence interval (CI): 43.3-68.7); 4-Part: 49.4 (CI: 42.2-56.7)] received a lower score than different surgical head-preserving methods such as ORIF [3-Part: 82.4 (CI: 76.6-86.9); 4-Part: 83.0 (CI:78.7-86.6)], intramedullary nailing [3-Part: 79.1 (CI:74.0-83.4)] or angle-stable plates [4-Part: 66.4 (CI: 59.7-72.4)]. The overall complication rate was 56%. The most common complications were fracture-displacement, malunion, humeral head necrosis and malreduction. The highest complication rates were documented for conventional plate and hemiarthroplasty and for AO-C, AO-A, for 3- and 4-part fractures. Only 25% of the data were reported with detailed classification results and the corresponding outcome scores. DISCUSSION: Despite the large amount of patients included, it is difficult to determine adequate recommendations for the treatment of proximal humeral fractures because a relevant lack of follow-up data impaired subsequent analysis. For displaced 3- and 4-part fractures head-preserving therapy received better outcome scores than hemiarthroplasty. However, a higher number of complications occurred in more complex fractures and when hemiarthroplasty or conventional plate osteosynthesis was performed. Thus, when informing the patient for consent, both the clinical results and the possibly expected complications with a chosen treatment modality should be addressed