Time trend analysis of Injury Severity score of adult trauma patients with emergent CT examination.

PURPOSE: Controversy exists about whole-body computed tomography (CT) as a primary screening modality for suspected multiple trauma patients. Therefore, the aim of this study was to analyze time trends of CT examinations for trauma patients in relation to the Injury Severity Score (ISS). METHODS: We retrospectively analyzed 561 adult trauma patients (mean age = 54 years) who were admitted to the trauma room of our hospital, immediately followed by a CT examination, in 2009, 2013 und 2017. Review of electronic patient charts was performed to determine the cause of injury. ISS was either calculated upon hospital charts and CT imaging reports or documented in the TraumaRegister DGU® for trauma patients with ICU treatment or ISS ≥ 16. RESULTS: An increasing number of CT examinations of acute trauma patients were performed at our hospital with 117 patients in 2009 compared to 192 in 2013 and 252 in 2017. Their mean age increased (50 years in 2009, 54 in 2013 and 55 in 2017;p = 0.046), whereas their mean ISS decreased over time (15.2 in 2009 compared to 12.1 in 2013 and 10.6 in 2017;p = 0.001), especially in women (15.1 in 2009, 11.8 in 2013 and 7.4 in 2017;p = 0.001 both), younger age groups (18 to 24 years:15.6 in 2009, 6.5 in 2013 and 8.9 in 2017; p = 0.033 and 25 to 49 years:15.0 in 2009, 11.2 in 2013 and 8.3 in 2017;p = 0.001) as well as motor vehicle collision (MVC) victims (16.2 in 2009, 11.8 in 2013 and 6.1 in 2017; p < 0.001). Trauma patients with a high ISS were especially more likely of older age (OR 1.02,p < 0.001) and with the type of incident being a fall (< 3 m: OR3.84,p < 0.001;>3 m: OR6.22,p < 0.001) compared to MVC. CONCLUSION: Previous studies suggesting a benefit of primary whole-body CT for trauma patients might not reflect the current patient population with decreasing ISS. Especially females, younger age groups and MVC patients might benefit from stricter selection criteria for receiving whole-body CT. Our results also emphasize the importance of prevention of fall or tumble for elderly people.

[Diagnosis of upper arm, elbow, and proximal lower arm fractures]. / Frakturdiagnostik an Oberarm, Ellenbogen und proximalem Unterarm.

The complex anatomy of the elbow joint enables a wide range of movement and complex functions in everyday and professional life. Typical injuries of this joint include a variety of different pathologies. Due to overlaying structures in plain radiographs, diagnosis of injuries to the elbow joint places high demands on the treating physicians and often needs further diagnostic imaging. The following article will give an overview of the most common of these injuries and their diagnosis.

Evaluation of fetuin-A as a predictor of outcome after surgery for osteoporotic fracture of the proximal femur.

BACKGROUND: In the elderly, osteoporotic fractures of the femur are associated with high morbidity and mortality. At the time of hospitalization and during pre-operative care identification of patients at risk for poor outcome despite an otherwise good clinical condition is challenging. We hypothesized that the serum concentration of fetuin-A during post-operative recovery might serve as a biomarker. METHODS: During a 15 months period patients admitted to our hospital for treatment of a femur fracture were registered on a voluntary basis and irrespective of age, underlying diseases and therapy. For all patients enrolled in this registry, blood was sampled for additional laboratory analysis. Patients with osteoporotic fractures were invited for follow-up examination about 2 years later. At this time, the functional outcome and clinical performance together with the handgrip strength as a surrogate measure of overall strength were assessed and the occurrence of additional fractures was recorded. Results from these assessments and the absence or presence of subsequent fractures were combined as summary score of outcome (SSO) and overall physical performance (oPP), a score derived by principal component analysis and relying on normally distributed data, only. RESULTS: 39 of 96 eligible patients were deceased during the follow-up period, while 45 consented to participate in the study. Patients with a SSO ≥ 17 pts were younger and had higher fetuin-A serum concentrations (each p < 0.05) during hospitalization compared to those with a SSO below 8 pts. Age at follow-up together with total serum protein and fetuin-A levels during post-operative recovery had significant influence on SSO and oPP. Fetuin-A at time of follow-up examination was not associated with outcome. CONCLUSIONS: Our results are in favor of fetuin-A as an important factor for fracture healing but do not support an association between fetuin-A at time of follow-up examination and either SSO or oPP.

[Complex regional pain syndrome]. / Komplexes regionales Schmerzsyndrom.

Complex regional pain syndrome (CRPS) is not a very common yet typical complication of extremity trauma in the daily practice of a trauma surgeon. The pathophysiology of this puzzling disease is still not completely understood and its impact on the patient cannot be overestimated. However, advantages have been made in diagnostics and therapy. While a multitude of different diagnostic systems has led to confusion in the past, we now have an internationally accepted, validated and easy to reproduce diagnostic algorithm in the form of the Budapest criteria. The adequate therapy is still a field for debate, but there is now a broad choice of conservative and interventional treatments for the out- and inpatient setting.

Modified step aerobics training and neuromuscular function in osteoporotic patients: a randomized controlled pilot study.

BACKGROUND: Training programs directed to improve neuromuscular and musculoskeletal function of the legs are scarce with respect to older osteoporotic patients. We hypothesized that a modified step aerobics training program might be suitable for this purpose and performed a randomized controlled pilot study to assess the feasibility of conducting a large study. Here we report on the training-related effects on neuromuscular function of the plantar flexors. PATIENTS AND METHODS: Twenty-seven patients with an age of at least 65 years were enrolled and randomized into control and intervention group. The latter received supervised modified step aerobics training (twice weekly, 1 h per session) over a period of 6 months. At baseline, and after 3 and 6 months neuromuscular function of the plantar flexors, i.e., isometric maximum voluntary torque, rate of torque development and twitch torque parameters were determined in detail in all patients of both groups. RESULTS: Twenty-seven patients (median age 75 years; range 66-84 years) were randomized (control group n = 14; intervention group n = 13). After 3 and 6 months of training, maximum voluntary contraction strength in the intervention group was significantly higher by 7.7 Nm (9.1%; 95% CI 3.3-12.2 Nm, P < 0.01) and 12.4 Nm (14.8%; 95% CI 6.4-18.5 Nm, P < 0.01) compared to controls. These changes were most probably due to neural and muscular adaptations. CONCLUSION: It is worthwhile to investigate efficacy of this training program in a large randomized trial. However, a detailed neuromuscular assessment appears feasible only in a subset of participants.

Fibroblast Growth Factor-23, Sclerostin, and Bone Microarchitecture in Patients With Osteoporotic Fractures of the Proximal Femur: A Cross-sectional Study.

This cross-sectional observational cohort study was designed to simultaneously investigate bone microarchitecture and serum markers of bone metabolism in elderly osteoporotic patients experiencing a trochanteric or femoral neck fracture. Special emphasis was put on renal function, sclerostin and fibroblast growth factor-23 (FGF-23). Eighty-two patients (median age: 84 years; 49 trochanteric fractures) scheduled for emergency surgery due to an osteoporotic fracture participated. Bone specimens for ex vivo microcomputed X-ray tomography were sampled during surgery. Blood samples for laboratory workup were collected before surgery (t0) and 1 day afterward (t1). Fifty-eight patients consented to dual-energy X-ray absorptiometry scanning of the lumbar spine and/or contralateral femoral neck after recovery during the in-patient stay. Samples were grouped according to the site of fracture. Regression coefficients were controlled for age and/or estimated glomerular filtration rate (eGFR), if appropriate. Patients experiencing a femoral neck fracture presented with better preserved renal function (eGFR) and lower C-terminal fragment of fibroblast growth factor-23 (cFGF-23) concentrations compared to those with trochanteric fractures. By contrast, serum sclerostin was similar at both time points and did not differ between groups. Age-adjusted correlation analysis revealed negative associations between eGFR and cFGF-23 determined at t1 (R=-0.34; p<0.05) as well as between eGFR and sclerostin levels at t0 (R=-0.45; p<0.05) in patients with trochanteric and femoral neck fractures, respectively. Our study provides evidence that not only an age-related decline of renal function but also the type of skeletal injury may contribute to the circulating concentrations of cFGF-23.

Intrabody application of eptotermin alpha enhances bone formation in osteoporotic fractures of the lumbar spine; however, fails to increase biomechanical stability - results of an experimental sheep model.

This study analyses the effect of eptotermin α application into fractured vertebrae. It is hypothesized that eptotermin α is capable to enhance bony healing of the osteoporotic spine. In 10 Merino sheep osteoporosis induction was performed by ovariectomy, corticosteroid therapy and calcium/phosphorus/vitamin D-deficient diet; followed by standardized creation of lumbar vertebral compression fractures (VCFs) type A3.1 and consecutive fracture reduction/fixation using expandable mesh cages. Randomly, intravertebral eptotermin α (G1) or no augmentation was added (G2). Macroscopic, micro-CT, and biomechanical evaluation assessed bony consolidation two months postoperatively: Micro-CT data revealed bony consolidation for all cases with significant increased callus development for G2 (60%) and BV/TV (bone volume/total volume 73.45%, osteoporotic vertebrae 35.76%). Neither group showed improved biomechanical stability. Eptotermin α enhanced mineralisation in VCFs in an experimental setup with use of cementless augmentation via an expandable cage. However, higher bone mineral density did not lead to superior biomechanical properties.

Vitamin D increases cellular turnover and functionally restores the skeletal muscle after crush injury in rats.

Insufficient skeletal muscle regeneration after injury often impedes the healing process and is accompanied by functional deficiencies or pain. The aim of our study was to provide evidence that vitamin D improves muscle healing after muscle injury. Therefore, we used male rats and induced an injury of the soleus muscle. After crush injury, animals received either 8.3 mg/kg (332,000 IU/kg) body weight vitamin D or vehicle solution, s.c. After assessment of muscle force at days 1, 4, 14, and 42 after injury, sampling of muscle tissue served for analysis of proliferation, apoptosis, satellite cells, and prolyl-4-hydroxylase-ß expression. Vitamin D application caused a significant increase in cell proliferation and a significant inhibition of apoptosis at day 4 after injury compared to control animals. The numbers of satellite cells were not influenced by the vitamin D application, but there was an increase in prolyl-4-hydroxylase-ß expression, indicative of increased extracellular matrix proteins. This cellular turnover resulted in a faster recovery of contraction forces at day 42 in the vitamin D group. Current data support the hypothesis that vitamin D promotes the regenerative process in injured muscle. Thus, vitamin D treatment may represent a promising therapy to optimize recovery after injury.

A pan-caspase inhibitor reduces myocyte apoptosis and neuropathic pain in rats with chronic constriction injury of the sciatic nerve.

BACKGROUND: Chronic constriction injury is a widely used model for neuropathic pain in rats. It presents with symptoms resembling human neuropathic pain, such as spontaneous pain, hyperalgesia, and allodynia. Recently, myocyte apoptosis was found in neuropathic rats as a possible promoter of pain and motor dysfunction. Our aim in this study was to demonstrate whether muscle cell apoptosis contributes to neuropathic pain in this animal model. METHODS: To clarify this issue, we examined pain, nutritive perfusion, and inflammation in muscle tissue as well as myocyte apoptosis in rats with neuropathic pain established by chronic constriction injury of the sciatic nerve. Animals received either the pan-caspase inhibitor zVAD (OMe)-fmk (n = 5) or equivalent volumes of vehicle (n = 6). Sham-operated rats served as controls (n = 6). RESULTS: At day 4 after nerve ligation, there were no signs of perfusion failure or muscle tissue inflammation in all experimental groups. However, animals treated with the vehicle had marked myocyte apoptosis, which was found almost completely blocked in zVA-Dtreated animals. The zVA-Dtreated animals presented with a significant reduction of pain upon heat, cold, and mechanical stimulation comparable with values found in sham controls. CONCLUSIONS: Myocyte apoptosis possibly contributes to thermal and mechanical allodynia in this experimental model for neuropathic pain. The development of neuropathic pain symptoms did not depend on disturbances in microcirculation or muscle tissue inflammation.

Functional assessment and outcome following surgical treatment of displaced tibial plateau fractures: a retrospective analysis.

PURPOSE: Patients with tibial plateau fractures (TPF) are at risk of long-term hampered bipedal locomotion. A retrospective single-center study using patient-related outcome measures and a sophisticated assessment of walking abilities was conducted. METHODS: Adults receiving surgical treatment of an isolated TPF between January 2012 and December 2016 received the KOOS questionnaire together with the invitation for an extensive follow-up examination on the clinical outcome including standardized assessment of the walking abilities (loadsol® system). Outcome was assessed relative to the severity of the injury or time to follow-up. Fractures were classified according to AO/OTA and Luo, respectively. RESULTS: 58 out of 132 eligible patients filled in the questionnaire and participated at a median follow-up of 3.05 years after injury. For the categories "pain", "mobility", and "daily life activities", all patients were rather satisfied and this was virtually not related to the time between fracture and assessment. Relevant limitations were reported for "sports and recreational activities" and "quality of life". Loading of the previously fractured leg was most evidently changed on stairs and outdoor walking. Outcome was not related to either fracture type severity or time from injury. CONCLUSION: Outcome after an isolated TPF is neither related to fracture type, severity of the fracture nor time from injury. Simple gait analysis techniques relying on different tasks appear to yield a more sophisticated image on functional deficits after TPF than classical exam of ground-level walking and correlate quite well with validated patient-related outcome measures as the KOOS.

Effects on Bone and Muscle upon Treadmill Interval Training in Hypogonadal Male Rats.

Testosterone deficiency in males is linked to various pathological conditions, including muscle and bone loss. This study evaluated the potential of different training modalities to counteract these losses in hypogonadal male rats. A total of 54 male Wistar rats underwent either castration (ORX, n = 18) or sham castration (n = 18), with 18 castrated rats engaging in uphill, level, or downhill interval treadmill training. Analyses were conducted at 4, 8, and 12 weeks postsurgery. Muscle force of the soleus muscle, muscle tissue samples, and bone characteristics were analyzed. No significant differences were observed in cortical bone characteristics. Castrated rats experienced decreased trabecular bone mineral density compared to sham-operated rats. However, 12 weeks of training increased trabecular bone mineral density, with no significant differences among groups. Muscle force measurements revealed decreased tetanic force in castrated rats at week 12, while uphill and downhill interval training restored force to sham group levels and led to muscle hypertrophy compared to ORX animals. Linear regression analyses showed a positive correlation between bone biomechanical characteristics and muscle force. The findings suggest that running exercise can prevent bone loss in osteoporosis, with similar bone restoration effects observed across different training modalities.

Inhibition of caspase mediated apoptosis restores muscle function after crush injury in rat skeletal muscle.

Although muscle regeneration after injury is accompanied by apoptotic cell death, prolonged apoptosis inhibits muscle restoration. The goal of our study was to provide evidence that inhibition of apoptosis improves muscle function following blunt skeletal muscle injury. Therefore, 24 rats were used for induction of injury to the left soleus muscle using an instrumented clamp. All animals received either 3.3 mg/kg i.p. of the pan-caspase inhibitor Z-valinyl-alanyl-DL: -aspartyl-fluoromethylketone (z-VAD.fmk) (n = 12 animals) or equivalent volumes of the vehicle solution DMSO (n = 12 animals) at 0 and 48 h after trauma. After assessment of the fast twitch and tetanic contraction capacity of the muscle at days 4 and 14 post injury, sampling of muscle tissue served for analysis of cell apoptosis (cleaved caspase 3 immunohistochemistry), cell proliferation (BrdU immunohistochemistry) as well as of muscle tissue area and myofiber diameter (HE planimetric analysis). Muscle strength analysis after 14 days in the z-VAD.fmk treated group revealed a significant increase in relative muscle strength when compared to the DMSO treated group. In contrast to the DMSO treated injured muscle, showing a transient switch towards a fast-twitching muscle phenotype (significant increase of the twitch-to-tetanic force ratio), z-VAD.fmk treated animals showed an enhanced healing process with a faster restoration of the twitch-to-tetanic force ratio towards the physiological slow-twitching muscle phenotype. This enhancement of muscle function was accompanied by a significant decrease of cell apoptosis and cell proliferation at day 4 as well as by a significant increase of muscle tissue area at day 4. At day 14 after injury z-VAD.fmk treated animals presented with a significant increase of myofiber diameter compared to the DMSO treated animals. Thus, z-VAD.fmk could provide a promising option in the anti-apoptotic therapy of muscle injury.

Reliability and consequences of intraoperative 3D imaging to control positions of thoracic pedicle screws.

INTRODUCTION: The insertion of thoracic pedicle screws (T1-T10) is subject to a relevant rate of malplacement. The optimum implantation procedure is still a topic of controversial debate. Currently, a postoperative computed tomography is required to evaluate the screw positions. The present study was undertaken to clarify whether intraoperative 3D imaging is a reliable method of determining the position of thoracic pedicle screws. METHODS: This prospective study involved 40 consecutive patients with thoracic spinal injuries, with intraoperative 3D scans being performed to determine the positions of 240 pedicle screws in T1-T10. The results of the 3D scans were compared with the findings of postoperative CT scans, using a clinical classification system. RESULTS: The positions of 204 pedicle screws could be viewed by means of both 3D and CT scans and the results compared. The 3D scans achieved a sensitivity of 90.9 % and a specificity of 98.8 %. The rate of misclassification by the 3D scans was 2.5 %. Nine pedicle screws were classified as misplaced and their position corrected intraoperatively (3.8 %). No screws required postoperative revision. CONCLUSIONS: Performing an intraoperative 3D scan enables the position of thoracic pedicle screws to be determined with sufficient accuracy. The rate of revision surgery was reduced to 0 %.

Tibial plateau fracture: does fracture classification influence the choice of surgical approach? A retrospective multicenter analysis.

PURPOSE: The role of classification systems for the choice of surgical approach and the management of tibial plateau fractures remains unclear. The purpose of this study was to investigate the potential of classification systems to choose the appropriate operative approach. Current surgical management strategies were investigated in a large multicenter assessment. METHODS: In this study, we retrospectively analyzed all patients with tibial plateau fractures that have received surgical treatment in one of the five Level I trauma facilities between 2012 and 2015. Fractures were classified in each center by a senior orthopedic surgeon using the AO/OTA and the Luo classification. Demographics, trauma mechanism, as well as the surgical approach were recorded. RESULTS: 538 patients (46.1% male, 53.9% female) were included. The anterolateral approach was used most frequently with 54.8% of all single approaches; 76.2% of all combined approaches used anterolateral as part of the approach. Combined approaches were used in 22.5% of the cases; a combination of the anterolateral and medial (10%), anterolateral, and posteromedial approach (5.8%) were used most frequently. The lowest number was found for the posterolateral (1.3%) and the combined approaches dorsal/anterolateral and medial/dorsal (1.7%, 1.1%). The AO/OTA classification showed a peak for 41.B2 (21.9%) and B3 (35.5%) fractures. Regarding the Luo classification, the dorsal column was involved in 45.7%. In contrast, only 14.7% of the surgical approaches used were able to address the dorsal tibial plateau potentially. CONCLUSION: The use of dorsal approach seems to be of minor importance than expected in daily clinical practice in this multicenter study. It was not possible to specify whether the AO/OTA or the Luo classification can reliably predict the choice of surgical approach. The operative treatment strategy of tibial plateau fractures seems to rather rely on the surgeons' experience, education, and preferences.

Preoperative skin antisepsis using chlorhexidine may reduce surgical wound infections in lower limb trauma surgery when compared to povidone-iodine - a prospective randomized trial.

BACKGROUND: For the prevention of surgical wound infections (SSIs), local microorganism counts can be lowered by skin antisepsis prior to surgical incisions. Until now, it has been unclear which antiseptic is the most effective. METHODS: This prospective randomized trial analyzed the efficacy of 2 frequently used agents in the reduction of postoperative wound complication rates after aseptic trauma surgery on the lower leg and foot. In the study, 279 consecutive participants were randomized; 112 received surgical skin preparations using chlorhexidine (CHX) (ChloraPrep; Becton Dickinson, Franklin Lakes, NJ) and 167 received preparations with povidone-iodine (PVP-I) (Braunoderm; B. Braun Melsungen AG, Melsungen, Germany). Primary clinical endpoints were SSIs and wound healing disorders (WHDs) within 6 months after surgery. Secondary outcome variables included demographic and perioperative risk factors for SSIs. RESULTS: Rates of WHDs and SSIs were significantly higher in the PVP-I treatment group, which experienced 9 SSIs and 12 WHDs (n = 21; 12.6%), compared to the CHX treatment group, which had 2 SSIs and 3 WHDs (n = 5; 4.5%) (P = .022). Perioperative risk factors for WHDs were obesity and longer surgery time, whereas SSIs were increased in participants with cardiovascular diseases and suction drainage. Logistic regression analysis showed that the odds of complications of wound healing were 3.5 times higher for PVP-I than for CHX (odds ratio = 3.5; 95% confidence interval, 1.1-11.2; P = .032). CONCLUSIONS: Preoperative skin antisepsis for trauma surgery of the lower leg and foot using CHX led to significantly fewer complications of wound healing when compared to PVP-I.

Calcaneal fracture fixation using a new interlocking nail reduces complications compared to standard locking plates - Preliminary results after 1.6 years.

INTRODUCTION: Surgical treatment of displaced intra-articular calcaneal fractures using a standard extended lateral approach for plate fixation is frequently associated with substantial wound healing complications and infections. This matched pairs analysis compares the new minimally-invasive calcaneal interlocking nailing technique to standard locking plate fixation in terms of reduction capacity, complication rates, and functional outcomes. METHODS: Forty feet in 38 patients (mean patient age 52.5 years, range 27-78) were treated with calcaneal locking nail (LN)(n=20) or locking plate (LP)(n=20) and followed clinically and radiologically for 20 months. Follow-up included radiological assessments and functional evaluations including the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score and the Foot Function Index (R-FFI). RESULTS: Times for surgery were similar for both techniques (LN 93min, range 34 to 175 vs. LP 101min, range 53 to 305). Length of hospital stay was significantly lower in the LN group (7.6 days, range 3 to 14 vs. LP 11 days, range 6 to 37). Time away from work was shorter by 3.5 days in LN group. LP group had superior range of motion in plantarflexion, eversion, and inversion at follow-up, while LP patients were superior in demonstrating a secure heelstrike (79% vs. LN 58%) and fewer needed permanent walking aids. AOFAS and FFI scores revealed no differences for both groups. Radiographs indicated an adequate reconstruction in both groups, followed by a slight loss of reduction at follow-up (LP 4.7° postoperative vs. follow-up; LN 5.1°). The overall complication rate between groups was significant with 5% complications in the LN group vs. 50% in the LP group (5% deep infection, 35% impaired wound healing, 5% hardware breakage, 5% superficial wound infection; LN: 5% superficial wound infection). CONCLUSIONS: The new calcaneal interlocking nail shows promising results in terms of reduction capacity and safety. Use of the minimally invasive locking nail technique minimized the risk of postoperative wound complications and achieved superior functional outcomes compared with standard locking plate fixation via the extended lateral approach.

Growth factor-mediated augmentation of long bones: evaluation of a BMP-7 loaded thermoresponsive hydrogel in a murine femoral intramedullary injection model.

BACKGROUND: Due to our aging population, an increase in proximal femur fractures can be expected, which is associated with impaired activities of daily living and a high risk of mortality. These patients are also at a high risk to suffer a secondary osteoporosis-related fracture on the contralateral hip. In this context, growth factors could open the field for regenerative approaches, as it is known that, i.e., the growth factor BMP-7 (bone morphogenetic protein 7) is a potent stimulator of osteogenesis. Local prophylactic augmentation of the proximal femur with a BMP-7 loaded thermoresponsive hydrogel during index surgery of an osteoporotic fracture could be suitable to reduce the risk of further osteoporosis-associated secondary fractures. The present study therefore aims to test the hypothesis if a BMP-7 augmented hydrogel is an applicable carrier for the augmentation of non-fractured proximal femurs. Furthermore, it needs to be shown that the minimally invasive injection of a hydrogel into the mouse femur is technically feasible. METHODS: In this study, male C57BL/6 mice (n = 36) received a unilateral femoral intramedullary injection of either 100 µl saline, 100 µl 1,4 Butan-Diisocyanat (BDI)-hydrogel, or 100 µl hydrogel loaded with 1 µg of bone morphogenetic protein 7. Mice were sacrificed 4 and 12 weeks later. The femora were submitted to high-resolution X-ray tomography and subsequent histological examination. RESULTS: Analysis of normalized CtBMD (Cortical bone mineral density) as obtained by X-ray micro-computed tomography analysis revealed significant differences depending on the duration of treatment (4 vs 12 weeks; p < 0.05). Furthermore, within different anatomically defined regions of interest, significant associations between normalized TbN (trabecular number) and BV/TV (percent bone volume) were noted. Histology indicated no signs of inflammation and no signs of necrosis and there were no cartilage damages, no new bone formations, or new cartilage tissues, while BMP-7 was readily detectable in all of the samples. CONCLUSIONS: In conclusion, the murine femoral intramedullary injection model appears to be feasible and worth to be used in subsequent studies that are directed to examine the therapeutic potential of BMP-7 loaded BDI-hydrogel. Although we were unable to detect any significant osseous effects arising from the mode or duration of treatment in the present trial, the effect of different concentrations and duration of treatment in an osteoporotic model appears of interest for further experiments to reach translation into clinic and open new strategies of growth factor-mediated augmentation.

Subchondral bone sclerosis and cancellous bone loss following OA induction depend on the underlying bone phenotype.

OBJECTIVES: Osteoarthritis (OA) is increasingly considered a disease of the whole joint, yet the interplay between the articular cartilage and the subchondral bone remains obscure. We here set out to investigate the impact of bone mass on the progression of surgically induced knee OA in the mouse. METHODS: OA was induced in the right knees of female C57BL/6 (low bone mass) and STR/ort (high bone mass) mice via anterior cruciate ligament transection and destabilization of the medial meniscus. At 36 weeks of age, left and right knee joints were histologically compared for cartilage degeneration and via microCT analysis for subchondral bone plate thickness. In addition, femora were analyzed for bone mass at diaphysis and distal meta- and epiphysis. RESULTS: The severity of cartilage deterioration did not differ under high and low bone mass conditions. However, the extent of bone sclerosis differed and was proportional to the baseline subchondral bone plate thickness. Moreover, the cancellous bone loss following OA progression was inversely related to the bone mass: high bone mass restricted the loss to the epiphysis, whereas low bone mass allowed for a more widespread loss extending into the metaphysis. CONCLUSIONS: Our results suggest that cartilage degeneration is independent of the underlying bone mass. In contrast, subchondral bone remodeling associated with OA progression seem to correlate with the initial bone mass and suggest an enhanced crosstalk between the deteriorating cartilage and the subchondral bone under low bone mass conditions.

Plyometric training improves voluntary activation and strength during isometric, concentric and eccentric contractions.

OBJECTIVES: This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. DESIGN: Twenty-seven participants were randomly assigned to the intervention or control group. METHODS: Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. RESULTS: After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. CONCLUSIONS: Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode.