BACKGROUNDFeatures of necrotic lesions and various interventions could affect the biomechanics of the femoral head. A three-dimensional finite-element analysis was designed to demonstrate necrotic femoral head stress changes with various sizes of necrotic lesions, and evaluate the effect of tantalum rods on preventing femoral head cracking.

METHODSFemoral computed tomography scans were used to build a normal three-dimensional finite-element femoral head model in a computer. Based on the normal model, necrotic models of different lesion diameters (15 mm, 20 mm and 30 mm) were created, as were the repaired models with tantalum rods for each diameter. After a series of meshing and force loading, the von Mises stress distributions, simulating single-legged stance, and stresses on specific points under loaded conditions were determined for each model.

RESULTSDeep exploration into the burdened area of the femoral head indicated that higher stresses to the femoral head were observed with a larger necrotic lesion; the largest stress concentration, 91.3 MPa, was found on the femoral head with a lesion diameter of 30 mm. By contrast, topical stress on the surface of the necrotic regions was lowered following implantation of a tantalum rod, and the changes in stress were significant in models with lesions of 15 mm and 30 mm in diameter, with the best biomechanical benefit from the tantalum rod found with a lesion diameter of 15 mm.

CONCLUSIONSFemoral heads with larger necrotic lesions usually have a higher stress concentration and a higher risk of collapse. Various sized lesions on the femoral head can benefit from the mechanical support offered by the implantation of a tantalum rod; however, femoral heads with smaller sized lesions may benefit more. A thorough evaluation of the lesion size should be conducted prior to the use of tantalum rod implants in the treatment of femoral head necrosis.

Femur Head ; physiology ; Femur Head Necrosis ; physiopathology ; Finite Element Analysis ; Humans ; Stress, Mechanical

Chronic myelogenous leukemia (CML) is a malignant clonal disorder of hemopoietic stem cells characterized by abnormal proliferation and accumulation of immature granulocyte. Leukostasis is one of the complications of CML and is characterized by partial or total occlusion of microcirculation by aggregation of leukemic cells and thrombi leading to respiratory, ophthalmic or neurologic symptoms. We experienced a rare case of avascular necrosis of the femoral head as the initial presentation of chronic myelogenous leukemia. A 24-year-old male patient was admitted to our hospital with pain in the right hip joint. The patient was diagnosed to be suffering from chronic myelogenous leukemia by packed marrow with granulocytic and megakaryocytic hyperplasia and the presence of Philadelphia chromosome. The right hip joint pain was attributed to avascular necrosis of the femoral head. And the avascular necrosis could be considered as the complication of chronic myelogenous leukemia due to microcirculatory obstruction of the femoral head. The avascular necrosis of the right femoral head was treated with bipolar hemiarthoplasty.
Male ; Leukemia, Myeloid, Chronic/*diagnosis/physiopathology ; Humans ; Femur Head Necrosis/*diagnosis/physiopathology ; Adult

OBJECTIVE: To analyze the feature of horizontal semicircular canal function at high and low-frequencies in Meniere's disease. METHOD: Thirty patients suffering from unilateral Meniere's disease were included in the research from 2013 June to 2014 June. Caloric test and video head impulse test were performed to evaluate the high low-frequency function of horizontal semicircular canal. RESULT: these patients were devided by the severity of unilateral weakness in caloric test. The gain value in video head impulse test, which reflects the high-frequency function of semicircular canal, were not different between the normal and mild abnormal group (P > 0.05), but were obviously different between the normal and mild-severe abnormal group, slight abnormal and mild-severe abnormal group (P < 0.05). Gain asymmetry, which reflects the high-frequency function of both side, has no difference between three groups (P > 0.05). CONCLUSION A part of Meniere's disease may have normal high, low-frequency function of horizontal semicircular canal. As patient suffering slight injury of low-frequency function, the high-frequency function keeps normal. As the injury of low-frequency function become mildly to severely, the damage of high-frequency function appears, but the symmetry still keeps balance.
Caloric Tests ; Head Impulse Test ; Humans ; Meniere Disease ; physiopathology ; Semicircular Canals ; physiopathology

PURPOSE: Whiplash associated disorders remain a major health problem in terms of impact on health care and on societal costs. Aetiology remains controversial including the old supposition that the cervical muscles do not play a significant role. This study examined the muscle activity from relevant muscles during rear-end impacts in an effort to gauge their influence on the aetiology of whiplash associated disorders. METHODS: Volunteers were subjected to a sub-injury level of rear impact. Surface electromyography (EMG) was used to record cervical muscle activity before, during and after impact. Muscle response time and EMG signal amplitude were analysed. Head, pelvis, and T1 acceleration data were recorded. RESULTS: The activities of the cervical muscles were found to be significant. The sternocleidomastoideus, trapezius and erector spinae were activated on average 59 ms, 73 ms and 84 ms after the impact stimulus, respectively, prior to peak head acceleration (113 ms). CONCLUSION The cervical muscles reacted prior to peak head acceleration, thus in time to influence whiplash biomechanics and possibly injury mechanisms. It is recommended therefore, that muscular influences be incorporated into the development of the new rear-impact crash test dummy in order to make the dummy as biofidelic as possible.
Acceleration ; Accidents, Traffic ; Biomechanical Phenomena ; Electromyography ; Head ; physiopathology ; Humans ; Models, Biological ; Neck Muscles ; physiopathology ; Reaction Time ; Whiplash Injuries ; etiology ; physiopathology

Traumatic brain injury (TBI) is a highly complex multi-factorial disorder. Animal models of TBI are used to elucidate primary and secondary injury mechanisms and pathophysiological changes and to provide the diagnostic and therapeutical basis for TBI. The choices of animal models depend upon the research objectives. However, various animal models have limitations. The models only can duplicate the pivotal injury mechanisms or a certain important pathophysiological course. The characteristics of human TBI can not fully be reflected by using these models. In the review, animal models of traumatic brain injury are classified as dynamic direct brain injury, indirect dynamic brain injury and combined neuro-traumatic models. Several common models are described for consideration.
Animals ; Biomechanical Phenomena ; Brain/physiopathology* ; Brain Injuries/physiopathology* ; Diffuse Axonal Injury/physiopathology* ; Disease Models, Animal ; Forensic Medicine ; Head Injuries, Closed/physiopathology* ; Head Injuries, Penetrating/physiopathology* ; Humans ; Mice ; Rats ; Reproducibility of Results

Shoulder surgeons need to be aware of the critical size of the glenoid or humeral osseous defects seen in patients with anterior shoulder instability, since the considerable size of osseous defect is reported to cause postoperative instability. Biomechanical studies have identified the size of the osseous defect which affects stability. Since engagement always occurs between a Hill-Sachs lesion and the glenoid rim, when considering the critical size of the Hill-Sachs lesion, we have to simultaneously consider the size of the glenoid osseous defect. With the newly developed concept of the glenoid track, we are able to evaluate whether a large Hill-Sachs lesion is an "on-track" or "off-track" lesion, and to consider both osseous defects together. In case of an off-track Hill-Sachs lesion, if the glenoid defect is less than 25%, no treatment is required. In this case, the Latarjet procedure or arthroscopic remplissage procedure can be a treatment option. However, if the glenoid defect is more than 25%, treatment such as bone grafting is required. This will convert an off-track lesion to an on-track lesion. After the bone graft or Latarjet procedure, if the Hill-Sachs lesion persists as off-track, then further treatment is necessitated. In case with an on-track Hill-Sachs lesion and a less than 25% glenoid defect, arthroscopic Bankart repair alone is enough.
Biomechanical Phenomena ; *Glenoid Cavity/injuries/pathology/physiopathology ; Humans ; *Humeral Head/injuries/pathology/physiopathology ; Shoulder Dislocation/physiopathology ; *Shoulder Joint/injuries/pathology/physiopathology

OBJECTIVETo investigate the manifestation of head shaking nystagmus (HSN) and the relationship between HSN and vestibular bithermal test while cross-checking the HSN and vestibular bithermal test.

METHODSOne hundred and twenty-four patients were examined by HSN and vestibular bithermal test. The latency and duration of HSN were observed and the dynamic changes of HSN were also investigated. The results of bithermal test were clarified by the values of canal paresis (CP).

RESULTSThere were 3 types of HSN, including 41 monophasic HSN, 11 biphasic HSN and 7 perverted HSN. The latency of monophasic HSN was (2.75 +/- 1.41) ms and the duration of it was (32.16 +/- 20.30) ms; as for the biphasic HSN, the first phase had no latency and the duration was (12.33 +/- 4.42) ms which was shorter than that of the second phase (57.00 +/- 17.19) ms (P < 0.01) and the latency of second phase was (57.00 +/- 17.19) ms. The value of canal paresis in the patients without HSN was lower than that in the patients with HSN.

CONCLUSIONSThe existence of HSN was dependent on the loss of the function horizontal canal and also on the stage of vestibular compensation. The variation of duration of HSN among individuals was great. In the acute stage of unilateral vestibular function loss, there appeared to be prominent HSN, and the direction of HSN is the same as that of spontaneous nystagmus. With the development of vestibular compensation, biphasic nystagmus would appear instead of monophasic HSN and the direction of first phase represent the direction of un-lesioned side. After compensation, HSN would not be elicited. However,when HSN existed, it suggested that the value of CP should exceed 25%. Perverted nystagmus pointed to central abnormality.

Adolescent ; Adult ; Caloric Tests ; Child ; Female ; Head ; physiopathology ; Humans ; Middle Aged ; Nystagmus, Pathologic ; physiopathology ; Paresis ; physiopathology ; Semicircular Canals ; physiopathology ; Young Adult

OBJECTIVETo study the natural head posture (NHP) of edentulous patients compared with dentate people and to understand NHP shift immediately inserting complete dentures and three months after denture wearing.

METHODSThe NHPs of twenty edentulous patients and twenty-two dentate subjects were recorded with cephalometric technique. The NTPs of edentulous patients were exposed three times, before inserting, right after inserting and three months after inserting dentures. The NHPs of dentate subjects were recorded once as a controlled group. Six angles measured from the radiographs were evaluated for the NHP and three angles and two linear measures for the mandibular position.

RESULTSCompared with dentate subjects, the craniomandibular angles of the edentulous patients increased and the camber of the cervical columns decreased, but changes of the NHP were not significant. The mandible showed a significant upward moving (P < 0.05) and an insignificant forward moving. At the time of denture insertion, the camber of the cervical columns significantly increased (P < 0.05). Three months after using the dentures, the craniomandibular angles of the patients obviously decreased. (P < 0.05).

CONCLUSIONThe shift of NHP after denture inserting does exist. The shifted NHP of the patients with dentures is a new balanced posture and closer to the normal position than the NHP of them without dentures.

Adult ; Aged ; Aged, 80 and over ; Cephalometry ; methods ; Denture, Complete ; Female ; Head ; physiopathology ; Humans ; Male ; Mandible ; physiopathology ; Middle Aged ; Mouth Rehabilitation ; methods ; Mouth, Edentulous ; physiopathology ; rehabilitation ; Neck ; physiopathology ; Posture

OBJECTIVETo verify the therapeutic effect of vascular dementia treated with three-line puncture on the Governor Vessel and Bladder Meridian on head.

METHODSSixty cases were randomly divided into a head-line puncture group and a routine acupuncture group, 30 cases in each group. In head-line puncture group, line puncture was applied on three lines of the Governor Vessel and Bladder Meridian from anterior hairline to occipital tuberosity. In routine acupuncture group, Yintang (GV 29), Fengchi (GB 20), Sishencong (EX-HN 1) penetrating to Baihui (GV 20) and Shenting (GV 24) penetrating to Shangxing (GV 23) were selected. Once a day, 5 times in a week and 8 weeks totally. Score was evaluated with Mini-Mental State Examination scale (MMSE) before and after treatment, and the therapeutic effects in both groups were compared.

RESULTSThe total effective rate of cognitive function was 76. 7% (23/30) in head-line puncture group, superior to that of 43.3% (13/30, P < 0.05) in routine acupuncture group. The MMSE scores in both groups were improved after treatment (both P < 0.01), and it in head-line puncture group was superior to that in routine acupuncture group (P < 0.01).

CONCLUSIONThree-line acupuncture on the Governor Vessel and Bladder Meridian on head can remarkably improve the cognitive function of vascular dementia, and the therapeutic effect is superior to that of routine acupuncture.

Acupuncture Therapy ; Aged ; Cognition ; Dementia, Vascular ; physiopathology ; psychology ; therapy ; Female ; Head ; physiopathology ; Humans ; Male ; Meridians ; Middle Aged ; Treatment Outcome

BACKGROUNDThere is a relatively high failure rate of the femoral component in patients with avascular necrosis at the intermediate-term follow-up. Improving the geometrical fit of the femoral stem against the medullary canal may help to provide long-term survivorship of the hip replacement for patients with avascular necrosis.

METHODSWe designed a specific stem, based on morphometric studies of proximal femoral canals in Chinese avascular necrosis patients and evaluated the stem by finite element analyses, comparing the novel stem with two commercially available and commonly used stems.

RESULTSThe morphometric data from avascular necrosis patients showed specific geometric differences in the proximal femoral canal, including profile curves in both the sagittal and coronary planes than the patients with femoral neck fracture. The shorter stemmed prostheses (Fitmore(®) and our stem) performed better than the longer stemmed prosthesis (VerSys(®)).

CONCLUSIONSThis is the first study to investigate the femoral geometries of Chinese avascular necrosis patients. Our stem provides better stability and is theoretically beneficial to bone ingrowth, which may increase the long-term stability and fixation of the implant.

Adult ; Aged ; Biomechanical Phenomena ; Female ; Femur Head Necrosis ; physiopathology ; Finite Element Analysis ; Humans ; Male ; Middle Aged