[Is there life after trauma surgery? Push forward and achieve a new equilibrium]. / Gibt es ein Leben nach der Unfallchirurgie? Durchstarten und ankommen im neuen Gleichgewicht!

After the active working life is completed it is not passive relaxation which will bestow enduring endorphin levels but the exact opposite: enduring tension! Quality of life and happiness in the third phase of life will only be found by trauma surgeons who remain seeking, not led by guidelines but self-determined and developing creativity and willingness to unfold.

[Biomechanical investigation of fixed-angle plate osteosynthesis of the proximal humerus]. / Biomechanische Untersuchung der winkelstabilen Plattenosteosynthese am proximalen Humerus.

INTRODUCTION: Proximal humeral fractures are common in the elderly population and are often associated with osteoporosis. Fixation of unstable proximal humeral fractures is problematic due to loss of fixation in osteoporotic bone. Fixed-angle devices are intended to provide superior mechanical stability due to the principle of an internal fixator. The NCB(R)-PH (non-contact-bridging proximal humerus) plate is a new fixed-angle device that locks the screws to the plate by secondary insertion of a locking cap. The aim of this study was to investigate if and to what extent NCB-PH plates applied in the locked mode provide higher mechanical stability in a proximal humerus fracture model. METHODS: For this investigation 16 (8 pairs) fresh frozen cadaveric humeri were used. An AO/ASIF 11-B 1 fracture of the proximal humerus was created in each bone and fixed with the NCB-PH plate. In a paired setting one bone was fixed with the plate in the locked mode and the other with the plate in the non-locked mode. The bones were then subjected to 100 cycles of axial loading and interfragmentary motion was measured. Bones surviving this test were subjected to load-to-failure testing and the force at which failure occurred was recorded. RESULTS: Bones fixed with the plate in the locked mode showed a statistically significant lower (51%) interfragmentary rotation compared to bones fixed with the plate in the non-locked mode. There was also a tendency for the bones fixed with the plate in the locked mode to fail first under higher forces (16%) during load-to-failure testing. CONCLUSION: The NCB-PH plate provides superior interfragmentary stability when used in the locked mode in a human cadaveric proximal humerus fracture model. Therefore, we recommend that all screws should be inserted in the locked mode. The results suggest that the NCB-PH plate in the locked mode provides higher primary postoperative stability thus permitting early functional treatment of the patient.

[Lower limb salvage using Pirogoff ankle arthrodesis : minimally invasive and effective fixation with the Ilizarov external ring fixator]. / Extremitätenerhalt durch tibiokalkaneare Arthrodese nach Pirogoff : Minimal-invasive und effektive Osteosynthese mit dem Ilizarov-Ringfixateur.

BACKGROUND: Irreversible destruction of the forefoot and midfoot generally leads to amputation. So-called limited surgical procedures such as transmetatarsal or Chopart/Syme amputations often result in poor clinical outcomes. Prostheses for these stumps are difficult to fit, a fact that reduces mobility for these patients, so reamputations are not rare. The very old method of tibiocalcaneal arthrodesis introduced by Pirogoff in 1854 can be an interesting surgical alternative in these cases, and the use of an Ilizarov external ring fixator may solve the stabilisation problem. MATERIAL AND METHODS: From 1 January 1990 to 1 January 2007, six patients underwent surgery for tibiocalcaneal Pirogoff arthrodesis with an external Ilizarov ring fixator. RESULTS: All patients could be evaluated postoperatively, with a medium follow-up time of 45.8 months. Outcome was measured with a modified ankle disarticulation score. In four cases, the outcome was good or excellent. Two cases (33%) with initially successful arthrodeses required transtibial reamputations because of secondary infection. All other cases healed very well. There was no delayed union or nonunion of the arthrodeses in our series. CONCLUSIONS: Tibiocalcaneal Pirogoff arthrodesis can be a surgical alternative in forefoot and midfoot destructions to achieve a well-covered, comfortable stump with a minimum of leg-length shortening that is easy to fit with a prosthesis and even allows some limited barefoot mobility. Bony fixation and healing of the arthrodesis are the challenges, but these difficulties can be avoided by using an external ring fixator system. Despite a failure rate of up to one-third, this method can be an effective solution due to the good functional outcome.

Rapid-inflation intermittent pneumatic compression for prevention of deep venous thrombosis.

BACKGROUND: Current treatment regimens that are designed to prevent deep venous thrombosis in patients undergoing orthopaedic procedures rely predominantly on drug prophylaxis alone. The purpose of this randomized clinical study was to evaluate the effectiveness of a mechanical adjunct to chemoprophylaxis that involves intermittent compression of the legs. METHODS: During a twenty-two month period, 1803 patients undergoing a variety of orthopaedic procedures were prospectively randomized to receive either chemoprophylaxis alone or a combination of chemoprophylaxis and mechanical prophylaxis. Nine hundred and two patients were managed with low-molecular-weight heparin alone, and 901 were managed with low-molecular-weight heparin and intermittent pneumatic compression of the calves for varying time periods. Twenty-four percent of the patients underwent total hip or knee joint replacement. Screening for deep venous thrombosis was performed on the day of discharge with duplex-color-coded ultrasound. RESULTS: In the chemoprophylaxis-only group, fifteen patients (1.7%) were diagnosed with a deep venous thrombosis; three thromboses were symptomatic. In the chemoprophylaxis plus intermittent pneumatic compression group, four patients (0.4%) were diagnosed with deep venous thrombosis; one thrombosis was symptomatic. The difference between the groups with regard to the prevalence of deep venous thrombosis was significant (p = 0.007). In the chemoprophylaxis plus intermittent pneumatic compression group, no deep venous thromboses were found in patients who received more than six hours of intermittent pneumatic compression daily. CONCLUSIONS: Venous thrombosis prophylaxis with low-molecular-weight heparin augmented with a device that delivers rapid-inflation intermittent pneumatic compression to the calves was found to be significantly more effective for preventing deep venous thrombosis when compared with a treatment regimen that involved low-molecular-weight heparin alone.

The effects of non-steroidal anti-inflammatory drug application on incisional wound healing in rats.

OBJECTIVE: There is evidence that non-steroidal anti-inflammatory drugs (NSAIDs) delay both epithelialisation and angiogenesis in the early phases of wound healing because of an antiproliferative effect. We investigated the influence of diclofenac, a non-selective NSAID, on incisional wound healing. METHOD: Ten male Wistar rats were given 5 mg diclofenac per kg bodyweight per day; 10 rats were given placebo pellets. After 10 days, unimpaired healing occurred independently of drug treatment both macroscopically and microscopically. Histomorphometry revealed a significant reduction (p = 0.006) in fibroblasts after diclofenac application (median 3 166 cells per mm2) compared with the placebo group (median 3940 cells per mm2). Epidermal thickness was not statistically different between the two groups. RESULTS: Diclofenac diminished the amount of fibroblasts in connective tissue, reflecting the known antiproliferative effect of NSAIDs on fibroblasts. Clinical healing was not affected. CONCLUSION: We recommend short-term diclofenac application for post-surgical and post-traumatic patients with wounds who would benefit from its antiphlogistic and analgesic effect. However, if wound healing is disturbed, the negative effect of diclofenac on fibroblasts should be considered. This is particularly relevant for patients with chronic wounds or conditions such as diabetes which can delay wound healing.

[Therapy indications and options for skeletal metastases]. / Therapieindikationen und -optionen bei ossären Metastasen.

Pathological fractures are dreaded complications due to skeletal metastasis. Modern oncological therapies and more sophisticated new radiological techniques such as MRI and positron emission tomography have improved multimodal treatment concepts. Surgical intervention is determined by the primary disease, general condition and life expectancy of the patient. The goals of surgical treatment are improvement of life quality, pain relief and maintenance of mobility.

[Osteitis. Infections of the locomotive system]. / Osteitis. Infektionen des Bewegungsapparates.

Infections of the locomotive system appear in many different forms such as acute inflammation of joints or bone following injury or surgical or chronic processes, often lasting for years. They demand an exact treatment plan not only to remove necrotic tissue but also for reconstruction of defects. A special problem is infection following alloplastic reconstruction of joints or spine. Multiple surgical procedures are required to hinder reinfection, restore function, and assure acceptable patient quality of life.

Predictive value of bone mineral density and morphology determined by peripheral quantitative computed tomography for cancellous bone strength of the proximal femur.

Peripheral quantitative computed tomography (pQCT) is an established diagnostic method for assessment of bone mineral density in the diagnosis of osteoporosis. However, the capacity of structural parameters of cancellous bone measured by high-resolution computed tomography remains to be explored. In 33 patients, bone mineral density (BMD) of the proximal femur was measured in vitro by pQCT using cylindrical biopsies from the intertrochanteric region harvested before the implantation of an artificial hip joint. By digital image analysis of CT scans, parameters derived from histomorphometry describing the microarchitecture of cancellous bone were measured. The biopsies were also loaded to failure by an uniaxial compression test to determine the biomechanical parameters, Young's modulus, strength, and maximum energy absorption (E(max)). Strong correlations were found for BMD vs. mechanical parameters (r = 0.73 for Young's modulus, r = 0.82 for strength, and r = 0.79 for E(max); p < 0.001, n = 29). The morphological parameters, bone volume per trabecular volume (BV/TV), apparent trabecular thickness (app.Tb.Th), apparent trabecular separation (app.Tb.Sp), and trabecular number (Tb.N), correlated significantly with all mechanical parameters. The combination of morphological parameters with BMD in a multivariate regression model led to an overall, but only moderate, increase in R(2) in all cases. Our data confirm the high predictive value of BMD for the mechanical competence of cancellous bone of the intertrochanteric region. However, quantification of cancellous bone structure by image analysis of CT scans may provide additional qualitative information for the analysis of bone strength.

Correlation of bone mineral density with strength and microstructural parameters of cortical bone in vitro.

The aim of this study was to evaluate the influence of microstructural parameters, such as porosity and osteon dimensions, on strength. Therefore, the predictive value of bone mineral density (BMD) measured by quantitative computed tomography (QCT) for intracortical porosity and other microstructural parameters, as well as for strength of cortical bone biopsies, was investigated. Femoral cortical bone specimens from the middiaphysis of 23 patients were harvested during total hip replacement while drilling a hole (dia. 4.5 mm) for the relief of the intramedullary pressure. In vitro structural parameters assessed in histological sections as well as BMD determined by quantitative computed tomography were correlated with yield stress, and elastic modulus assessed by a compression test of the same specimens. Significant correlations were found between BMD and all mechanical parameters (elastic modulus: r = 0.69, p < 0.005; yield stress: r = 0.64, p < 0.005). Significant correlations between most structural parameters assessed by histology and yield stress were discovered. Structural parameters related to pore dimensions revealed higher correlation coefficients with yield stress (r = -0.69 for average pore diameter and r = -0.62 for fraction of porous structures, p < 0.005) than parameters related to osteons (r = 0.60 for osteon density and average osteonal area, p < 0.005), whereas elastic modulus was predicted equally well by both types of parameters. Significant correlations were found between BMD and parameters related to porous structures (r = 0.85 for porosity, 0.80 for average pore area, and r = 0.79 for average pore diameter in polynomial regression, p < 0.005). Histologically assessed porosity correlated significantly with parameters describing porous structures and haversian canal dimensions. Our results indicate a relevance of osteon density and fraction of osteonal structures for the mechanical parameters of cortical bone. We consider the measurement of BMD by quantitative computed tomography to be helpful for the estimation of bone strength as well as for the prediction of intracortical porosity and parameters related to porous structures of cortical bone.

Fluorine-18-FDG PET and technetium-99m antigranulocyte antibody scintigraphy in chronic osteomyelitis.

UNLABELLED: The aim of this study was to assess the usefulness of PET with 2-18F-fluoro-2-deoxy-D-glucose (FDG), as compared to immunoscintigraphy (IS) with 99mTc-labeled monoclonal antigranulocyte antibodies (AGAbs), in the detection of chronic osteomyelitis. METHODS: Fifty-one patients suspected of having chronic osteomyelitis in the peripheral (n = 36) or central (n = 15) skeleton were evaluated prospectively with static FDG PET imaging and combined 99mTc-AGAb/99mTc-methylene diphosphonate (MDP) bone scanning within 5 days. FDG PET and IS were evaluated in a blinded and independent manner by visual interpretation, which was graded on a five-point scale of two observers' confident diagnosis of osteomyelitis. Receiver operating characteristic (ROC) curve analysis was performed for both imaging modalities. The final diagnosis was established by means of bacteriologic culture of surgical specimens and histopathologic analysis (n = 31) or by biopsy and clinical follow-up over 2 yr (n = 20). RESULTS: Of 51 patients, 28 had osteomyelitis and 23 did not. According to the unanimous evaluation of both readers, FDG PET correctly identified 27 of the 28 positives and 22 of the 23 negatives (IS identified 15 of 28 positives and 17 of 23 negatives, respectively). The area under the ROC curve was 0.97/0.97 (reader 1/reader 2) for FDG PET and 0.87/0.90 for IS, with a high degree of interobserver concordance (K-values were 0.96 for FDG PET and 0.91 for IS). In the central skeleton, the ROC curve area was 0.98/1.00 for FDG PET and 0.71/0.77 for IS (p<0.05). On the basis of ROC analysis, the overall accuracies of FDG PET and IS in the detection of chronic osteomyelitis were 96%/96% and 82%/ 88%, respectively. With regard to the optimal threshold values, sensitivity and specificity were 100%/97% and 95%/95% with FDG PET, compared to 86%/92% and 77%/82% with IS, respectively. CONCLUSION: In the peripheral skeleton, both FDG PET and combined 99mTc-AGAb/99mTc-MDP scanning are appropriate imaging modalities to diagnose chronic osteomyelitis. FDG PET additionally allows reliable differentiation between osteomyelitis and infection of the surrounding soft tissue. In the central skeleton within active bone marrow, FDG PET is highly accurate and superior to AGAb imaging in the diagnosis of chronic osteomyelitis, which frequently presents as a nonspecific photopenic lesion at scintigraphy with labeled white blood cells.

Chest trauma and its impact on the release of vasoactive mediators.

Every year, major chest injury is involved in 56% of deaths in trauma victims. Blunt chest trauma apparently plays a crucial role in trauma-induced death of multiply injured patients. Therefore, the aim of this study was to evaluate the impact of different types of injuries, including lung tissue damage, on the release of various prostanoids. In a prospective study, the release of arachidonic acid (AA) metabolites was estimated in patients suffering blunt chest trauma alone, i.e., single thoracic injury, and in multiple injured patients including blunt chest trauma. The results were compared with those of patients suffering from single long bone fractures of the leg without additional injury. The plasma concentrations of the AA metabolites, prostacyclin, thromboxane, prostaglandin F2 alpha, and prostaglandin M were determined immediately after admission and in hourly and daily intervals thereafter. Despite clearly different injury scores, elevated levels of circulating AA metabolites were found in the plasma in all patients. This study reveals that any trauma increases significantly the release of prostanoids into the peripheral blood without regard to the impact of tissue damage. This phenomenon is, however, most pronounced following lung injury. On the basis of these results we suggest that there is a specific impact of those mediators in blunt chest trauma. The prostanoids apparently are suitable to describe and even to monitor the extent of thoracic trauma, thus giving additional information in some respect to the individual outcome.

Early posttraumatic increase in production of nitric oxide in humans.

Since nitric oxide (NO) contributes to both circulatory disorders and host defense, we analyzed the NO production in (poly)trauma patients (pts) in a prospective (pre)clinical study starting as early as at the scene of accident. Upon approval of the local IRB/EC, 85 multiple injured pts were enrolled. Subsets were performed according to trauma severity (ISS) and injury pattern, and between survivors versus nonsurvivors. The first blood sample was collected at the scene of accident, then in hourly to daily intervals. NO production was assessed by measuring nitrate+nitrite plasma levels. To estimate dilution effects, all values were calculated according to the actual plasma protein content. The extent of trauma was appraised by C-reactive protein (CRP) levels. Immediately after trauma, NO2-+NO3- plasma levels were always elevated. This was most pronounced in thoracic injury, irrespective of whether it was combined with multiple trauma. Nitrate+nitrite levels returned to normal within 24 h. CRP generation increased during 12 h following trauma and was most marked in severest trauma (ISS >50). For the first time, we show very early data following major trauma that demonstrate that NO overproduction starts immediately after trauma. However, systemic NO2-+NO3- levels actually reflect the severity of injury only during the first 2 h. Thereafter, NO generation is rather related to the individual trauma pattern, e.g., chest trauma. Nonetheless, the role of NO after severe trauma and especially in thoracic injury remains unclear and should further be elucidated in a specific study.

Trauma severity-dependent changes in AT III activity.

Trauma may cause a relevant reduction in antithrombin (AT) III activity, which is associated with adverse events. The very early changes in AT III activity after accident trauma are still unclear and possible relations with Interleukin (IL)-6, which is known to interact with AT III, have not been investigated so far. Upon approval of the IRB/IEC, 30 patients were enrolled with multiple injuries (ISS 9-75). Groups were performed according to injury severity, IL-6 concentration, and survivors versus non-survivors. Blood samples were collected at the scene of accident then at 2, 4, 6, 12, and 24 h and at day 3, 5, 10 and 15. No patient received AT III concentrates. In all groups a reduction in AT III activity occurred, which was most pronounced in very severe injuries. The activity re-increased spontaneously and steadily in all groups regardless of the IL-6 concentration. There was no clear impact of the AT III activity on survival.

Prediction of cortical bone porosityIn Vitro by microcomputed tomography.

The high importance of intracortical porosity for mechanical strength of cortical bone has been established. The contribution of other parameters of microstructure such as osteon dimensions for strength is in discussion. The aim of this study was to evaluate the predictive value of microcomputed tomography (µCT) for porosity and other microstructural parameters of cortical bone in cortical bone biopsies. Femoral cortical bone specimens from the middiaphysis of 24 patients were harvested during the procedure of total hip replacement at the location where normally one hole (Ø 4.5 mm) for the relief of the intramedullary pressure is placed.In vitro intracortical porosity and bone mineral density (BMD) measurements by µCT were compared with structural parameters assessed in histological sections of the same specimens. A strong correlation was found between intracortical porosity measured by µCT and histological porosity (r=0.95,P<0.0001). Porosity measured by µCT was also a strong predictor for other parameters describing dimensions of porous structures. BMD-1 was associated with osteonal area (r=-0.76,P<0.0001). We consider the measurement of porosity by µCT as a very potent procedure for assessing intracortical porosity and parameters related to porous structures of cortical bone nondestructivelyin vitro.

Is interleukin 6 an early marker of injury severity following major trauma in humans?

HYPOTHESIS: Interleukin 6 (IL-6), a multifunctional cytokine, is expressed by various cells after many stimuli and underlies complex regulatory control mechanisms. Following major trauma, IL-6 release correlates with injury severity, complications, and mortality. The IL-6 response to injury is supposed to be uniquely consistent and related to injury severity. Therefore, we designed a prospective study starting as early as at the scene of the unintentional injury, to determine the trauma-related release of plasma IL-6 in multiple injured patients. PATIENTS AND METHODS: On approval of the local ethics committee, 94 patients were enrolled with different injuries following trauma (Injury Severity Score [ISS] median, 19; range, 3-75). The patients were rescued by a medical helicopter. Subsets were performed according to the severity of trauma--4 groups (ISS, <9, 9-17, 18-30, and >32)-and survival vs nonsurvival. The first blood sample was collected at the scene of the unintentional injury before cardiopulmonary resuscitation, when appropriate. Then, blood samples were collected in hourly to daily intervals. Interleukin 6 plasma levels were determined using a commercial enzyme-linked immunosorbent assay test. The short-term phase protein, C-reactive protein, was measured to characterize the extent of trauma and to relate these results to IL-6 release. RESULTS: As early as immediately after trauma, elevated IL-6 plasma levels occurred. This phenomenon was pronounced in patients with major trauma (ISS, >32). Patients with minor injury had elevated concentrations as well but to a far lesser extent. In surviving patients, IL-6 release correlated with the ISS values best during the first 6 hours after hospital admission. All patients revealed increased C-reactive protein levels within 12 hours following trauma, reflecting the individual injury severity. This was most pronounced in patients with the most severe (ISS, >32) trauma. CONCLUSIONS: To our knowledge, this is the first study that elucidates the changes in the IL-6 concentrations following major trauma in humans as early as at the scene of the unintentional injury. The results reveal an early increase of IL-6 immediately after trauma. Moreover, patients with the most severe injuries had the highest IL-6 plasma levels. There is strong evidence that systemic IL-6 plasma concentrations correlate with ISS values at hospital admission. Therefore, IL-6 release can be used to evaluate the impact of injury early regardless of the injury pattern.

Is the activity of soluble CD14 enhanced following major trauma?

BACKGROUND: The molecule CD14 acts as a receptor for the protein-bound endotoxin (lipopolysaccharide [LPS]) complex and mediates the cellular effects of LPS. The soluble formation, sCD14, is supposed to neutralize circulating LPS (i.e., LPS antagonist) or transfer LPS effects to endothelial cells (i.e., LPS agonist). OBJECTIVE: To elucidate the release of sCD14 per se in patients with major trauma in the early posttrauma period. Our a priori hypothesis was that sCD14 release depends on the plasma LPS concentration simultaneously measured. PATIENTS: In a prospective study, 65 patients with multiple injuries (Injury Severity Score, 9-75) were enrolled. The patients were rescued by the medical helicopter service and directly admitted to our clinics. The plasma concentrations of sCD14 (enzyme immunoassay) and LPS (chromogenic limulus amebocyte lysate test) were analyzed. The first blood sample was collected immediately at the accident site. The following samples were drawn at intervals from 2 hours to daily for 2 weeks. RESULTS: Sixty-one patients survived the observation time. Immediately after trauma, their mean sCD14 level was not different from that of healthy individuals. Two hours later, a pronounced increase of sCD14 was observed and sustained throughout the observation period. Even nonsurvivors showed an increased sCD14 release, but less pronounced. In all patients, plasma LPS levels were elevated during the first 12 hours. CONCLUSIONS: Major trauma caused an increased release of sCD14. This elevation, however, was not correlated to LPS levels or to the severity of trauma (estimated by trauma scores). We found no evidence that sCD14 levels are of prognostic value regarding survival. Furthermore, the release of sCD14 did not occur in an LPS-neutralizing manner, but rendered possible an LPS-independent mechanism.

Ilizarov callus distraction produces systemic bone cell mitogens.

We tested the hypothesis that the application of strain during callus distraction induces systemic osteoblast stimulating factors that enhance osteoblast activity both locally and systemically. To study the systemic occurence of strain-induced osteoblast stimulating factor during callus distraction, we investigated the mitogenic capacity of sera from 12 patients who had undergone callus distraction on the osteoblastic cell line SaOS-2 (part I). Serum samples from six patients who had undergone rigidly fixed high tibial osteotomy (i.e., without distraction) served as controls. The sera were assayed for platelet-derived growth factor and transforming growth factor-beta. In part II of the study, the in vitro effects of mechanical strain were investigated in a simplified model by cyclic stimulation of osteoblast cultures isolated from cortical bone explants from the same patients; a specially developed apparatus was used for cell-stretching. Sera taken during the third to fourth week of callus distraction demonstrated a significant increase in proliferation of SaOS-2 cells (p < 0.005). In contrast, sera from patients who had had an osteotomy failed to induce or decreased the mitogenic capacity of SaOS-2 cells. The concentration of platelet-derived growth factor increased significantly (p < 0.01) in sera from both the patients who had undergone callus distraction and the controls who had had osteotomy. However, the level of transforming growth factor-beta was increased (p < 0.05) in the sera from the patients who had distraction (sera that stimulated proliferation of SaOS-2 cells), but the level was not increased in the sera from patients who had osteotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

A new acceleration apparatus for the study of whiplash with human cadaveric cervical spine specimens.

The biomechanics of whiplash is often studied using cadaveric cervical spine specimens. One of the most important points in this kind of study is to create realistic loading conditions. The aim of the present project therefore was to develop an acceleration apparatus, which allows the study of whiplash with human cadaveric cervical spine specimens under as realistic loading conditions as possible. The new acceleration apparatus mainly consisted of a sled, a pneumatic acceleration unit and a railtrack and offered several unique features to create more realistic loading conditions. Among these features, the possibility to simulate the passive movements of the trunk is of capital importance. In this new apparatus, first, the general feasibility of whiplash experiments was studied, second, the reproducibility of the impacts was quantified and third, the effect of simulated movements of the trunk on accelerations and loads was examined. In the new acceleration apparatus various types of collisions could reproducibly be simulated. Simulated passive movements of the trunk strongly influenced the loading pattern of the neck. Without pivoting a steep increase of all loading parameters could be observed. This increase was less pronounced if pivoting was allowed. In conclusion, biomechanical aspects of whiplash could reproducibly be examined in the new acceleration apparatus. Due to its significant effects on the loading of the neck, pivoting of the trunk should always be taken into account in future experiments on the biomechanics of whiplash in which isolated cervical spine specimens are used.

Human osteoblasts from younger normal and osteoporotic donors show differences in proliferation and TGF beta-release in response to cyclic strain.

Mechanical stimulation of bone tissue by physical activity stimulates bone formation in normal bone and may attenuate bone loss of osteoporotic patients. However, altered responsiveness of osteoblasts in osteoporotic bone to mechanical stimuli may contribute to osteoporotic bone involution. The purpose of the present study was to investigate whether osteoblasts from osteoporotic patients and normal donors show differences in proliferation and TGF beta production in responses to cyclic strain. Human osteoblasts isolated from collagenase-treated bone explants of 10 osteoporotic patients (average age 70 +/- 6 yr) and 8 normal donors (average age 54 +/- 10 yr) were plated into elastic rectangular silicone dishes. Subconfluent cultures were stimulated by cyclic strain (1%, 1 Hz) in electromechanical cell stretching apparatus at three consecutive days for each 30 min. The cultures were assayed for proliferation, alkaline phosphatase activity and TGF beta release in each three parallel cultures. In all experiments, osteoblasts grown in the same elastic dishes but without mechanical stimulation served as controls. Significant differences between stimulated cultures and unstimulated controls were determined by a paired two-tailed Wilcoxon test. In comparison to the unstimulated controls, osteoblasts from normal donors significantly increased proliferation (p = 0.025) and TGF beta secretion (p = 0.009) into the conditioned culture medium. In contrast, osteoblasts from osteoporotic donors failed to increase both proliferation (p > 0.05) and TGF beta release (p > 0.05) in response to cyclic strain. Alkaline phosphatase activity was not significantly affected (p > 0.05) in normal as well as osteoporotic bone derived osteoblasts. These findings suggest a different responsiveness to 1% cyclic strain of osteoblasts isolated from normal and osteoporotic bone that could be influenced by both the disease of osteoporosis and the higher average age of the osteoporotic patient group. While osteoblasts from osteoporotic donors failed to increase proliferation and TGF beta release under the chosen mechanical strain regimen that stimulated both parameters in normal osteoblasts, it is possible that some other strain regimen would provide more effective stimulation of osteoporotic cells.

Primary repair for posterior cruciate ligament injuries. An eight-year followup of fifty-three patients.

We reviewed 53 of 58 patients who had primary repairs of posterior cruciate ligament injuries between 1981 and 1988. Sixteen patients had isolated posterior cruciate ligament ruptures, 16 had complex injuries with capsular and collateral ligament involvement, and 21 had additional anterior cruciate ligament ruptures. Forty-six patients were treated by transosseous multiple-loop sutures and seven with bony avulsions by screw osteosynthesis. The mean follow-up time was 7.5 years (range, 3 to 12). All patients were examined subjectively (questionnaire) and objectively (clinical examination, KT-1000 arthrometer, functional testing, radiographs, and Cybex II isokinetic strength analysis). The results were graded according to the International Knee Documentation Committee evaluation form and the Lysholm score. The average Lysholm score was 82.4 (range, 40 to 100). Thirty-eight patients returned to their preinjury activities at the same intensity level. The patients' subjective assessments were normal or nearly normal in 35 patients. The posterior drawer test was negative or 1+ in 46 patients. Cybex isokinetic strength analysis revealed a decrease in quadriceps muscle strength of the involved limb by 10.5% (P < 0.01). Our data suggest that primary repair of posterior cruciate ligament ruptures provides good results after 8 years in approximately two thirds of the patients. Distal ligamentous ruptures, lack of athletic activity, and temporary olecranization correlated with poor results. Bony avulsions, midsubstance or proximal ruptures, and athletic activity correlated with good results.