Brake reaction time before and after surgery for patients with sequestrectomy versus conventional microdiscectomy

The aim of this study was to compare the effects of sequestrectomy versus conventional microdiscectomy on breaking response time (BRT) for lumbar disc herniation (LDH). BRT is the key factor for return to drive recommendations after surgery. A prospective clinical study was conducted. Patients aged 25-65 years who underwent surgery for lumbar disc herniation and held a valid motorcar driving license were recruited in a single institution. The patients were assessed before surgery, immediately after the surgery and at the follow up examination 30 days post-surgery. BRT was measured using a driving simulator, a visual analogue scale (VAS) was used for pain assessment. BRT values were compared with BRT values of a healthy control group. In patients treated with microdiscectomy BRT reduced from 749 (±223) msec before surgery to 649 (±223) msec immediately after the surgery. In the sequestrectomy group BRT reduced from 852 (±561) msec before surgery to 693 (±173) msec immediately after the surgery. BRT at follow up was 610 (±145) msec for patients treated with microdiscectomy and 630 (±98) msec for patients operated with sequestrectomy. BRT for healthy controls was 487 (±116) msec. Pain improved significantly for both patient samples. Sequestrectomy and microdiscectomy were associated with similar effects on pain and BRT after surgery. There was no statistically significant difference between BRT of both patient samples at 30 days follow up examination. Both surgical techniques showed a positive effect on BRT. No statistically significant difference between sequestrectomy and microdiscectomy on BRT could be found.

Braking reaction time before and after surgery for patients with recurrent lumbar disc herniation

OBJECTIVE

The positive effect of primary lumbar disc surgery on braking reaction time (BRT) has already been shown. The authors investigated the effect of recurrent lumbar disc herniation surgery on BRT.

METHODS

Twenty-four patients (mean age 49.9 years) were investigated for BRT 1 day before surgery, postoperatively before hospital discharge, and 4 to 5 weeks after surgery. Thirty-one healthy subjects served as a control group.

RESULTS

Significant improvement of BRT following surgery was found in all patients (p < 0.05). For patients with right-sided recurrent disc herniation, median BRT was 736 msec before surgery, 685 msec immediately postoperatively, and 662 msec at follow-up. For patients with left-sided recurrent disc herniation, median BRT was 674 msec preoperatively, 585 msec postoperatively, and 578 msec at follow-up. Control subjects had a median BRT of 487, which differed significantly from the patient BRTs at all 3 test times (p < 0.05).

CONCLUSIONS

A significant reduction in BRT in patients with recurrent disc herniation was found following lumbar disc revision surgery, indicating a positive impact of surgery. Due to the improvement in BRT observed immediately after surgery, we conclude that it is appropriate to recommend that patients keep driving after being discharged from the hospital.

Driving ability after right-sided puncture of the common femoral artery during coronary angiography

Objectives/background

To assess brake reaction time (BRT; key factor in driving ability) in patients receiving transfemoral coronary angiography (CAG). We assumed that patients would have a significantly impaired BRT after the procedure.

Methods

A prospective, observational study design was applied. Consecutive patients undergoing right-sided transfemoral CAG as part of the clinical routine were included. An experimental driving simulator was used to determine BRT after receiving a visual stimulus. The subjects applied the brake with their right foot as quickly as possible when a red-light signal appeared. The time interval between stimulus and brake application was taken as BRT. In addition to the total BRT, also its components were determined: neurologic reaction time, foot transfer time and brake travel time. BRT was determined before and 1 day after CAG (pre-post comparison).

Results

71 patients were included in the analysis (58 male, age 61 ± 9 years). Total BRT was 594 ± 188 and 591 ± 198 ms before and after the CAG procedure, respectively (p = 0.270). Similarly, also the BRT components ‘foot transfer time’ and ‘brake travel time’ did not show significant differences between the two test occasions. However, neurologic reaction time decreased from 269 ± 67 to 255 ± 64 ms (p = 0.036).

Conclusions

We found no impairment of BRT on the first day after puncture of the right-sided femoral artery in patients undergoing CAG. Therefore, with regard to BRT, it is regarded safe to resume driving from day 1 after CAG. Other factors of driving safety beyond BRT must also be considered.

Effect of hip braces on brake response time: Repeated measures designed study

BACKGROUND

The question whether or not a patient with a hip brace should drive a car is of obvious importance because the advice given to patients to resume driving is often anecdotal as few scientific data are available on this specific subject.

OBJECTIVES

To assess driving ability (brake response time) with commonly used hip braces.

STUDY DESIGN

Repeated measures design.

METHODS

Brake response time was assessed under six conditions: (1) without a brace (control), (2) with a typical postoperative hip brace with adjustable range of motion and the settings: unrestricted, (3) flexion limited to 70°, (4) extension blocked at 20° hip flexion, (5) both flexion and extension limited (20°/70°) and (6) an elastic hip bandage. Brake response time was assessed using a custom-made driving simulator as used in previous studies. The participants were a convenience sample of able-bodied participants.

RESULTS

A total of 70 participants (35 women and 35 men) participated in our study. Mean age was 31.1 (standard deviation: 10.6; range: 21.7-66.4) years. A significant within-subject effect for brake response time was found ( p = 0.009), but subsequent post hoc analyses revealed no significant differences between control and the other settings.

CONCLUSION

Based on our findings, it does not seem mandatory to recommend driving abstinence for patients wearing a hip orthosis. We suggest that our results be interpreted with caution, because (1) an underlying pathological hip condition needs to be considered, (2) the ability to drive a car safely is multifactorial and brake response time is only one component thereof and (3) brake response time measurements were performed only with healthy participants. Clinical relevance Hip braces are used in the context of joint-preserving and prosthetic surgery of the hip. Therefore, clinicians are confronted with the question whether to allow driving a car with the respective hip brace or not. Our data suggest that hip braces do not impair brake response time.

Driving ability after right-sided ankle arthroscopy--A prospective Study

INTRODUCTION

Due to the current lack of evidence the aim of this study was to investigate the driving ability after right-sided ankle arthroscopy.

MATERIALS AND METHODS

Nineteen patients underwent right-sided ankle arthroscopy. Brake response time (BRT) was assessed preoperatively, 2 days, 2 weeks, 6 weeks, and 12 weeks postoperative. We also determined patients' clinical outcome (AOFAS and AOS questionnaires) and their driving frequency.

RESULTS

BRT was 606ms preoperatively and changed to 821ms 2 days postoperative (p<0.001). The further postoperative BRT course was 606ms (2 weeks), 596ms (6 weeks) and 603ms (12 weeks) (p=n.s.). In addition, a significant influence of the AOS and AOFAS scores on BRT was found, namely poorer clinical outcome also leads to a prolonged BRT (p<0.01 for both). BRT was significantly prolonged in patients with little driving frequency (p=0.001). Furthermore, the 'time-by-driving interaction' was significant (p=0.018), which means the BRT-peak on the second day was much lower in low-frequency drivers.

CONCLUSIONS

From the findings made in the current study we conclude that a driving abstinence of two weeks is necessary following right-sided ankle arthroscopy. Greater driving frequency and good clinical outcome seem to be associated with better driving ability. However, for the time being no exceptions should be made from the above-mentioned recommendation on driving abstinence.

Effect of surgical shoes on brake response time after first metatarsal osteotomy--a prospective cohort study

Background

The aim of this study is to assess patients’ driving ability when wearing surgical shoes following right-sided first metatarsal osteotomy.

Methods

From August 2013 to August 2015, 42 consecutive patients (mean age 54.5 years) with right-sided hallux valgus deformity underwent first metatarsal osteotomy. Patients were tested for brake response time (BRT) 1 day preoperatively (control run) and at 2 and 6 weeks postoperatively. Two different types of foot orthosis were investigated. BRT was assessed using a custom-made driving simulator.

Results

Preoperative BRT was 712 msec (standard deviation (SD), 221 msec). BRT was significantly slower at all tested postoperative times than preoperatively (p < 0.001). The patients showed significant impaired brake response time when wearing surgical shoes. Mean global American Orthopaedic Foot and Ankle Society (AOFAS) outcome score and AOFAS pain and alignment subscores increased postoperatively (p < 0.001).

Conclusions

From our findings, we recommend driving abstinence for a minimum of 6 weeks postoperatively when using a surgical shoe after bunionectomy. However, patients should have sufficient recovery, exercise, and training before resuming driving a car, because safety is always a priority.

Trial registration

ClinicalTrials.gov, NCT02354066

The effect of ankle brace type on braking response time-A randomised study

INTRODUCTION

The question whether or not a patient with an ankle brace should drive a car is of obvious importance because brake response time (BRT) is considered one of the most important factors for driving safety.

MATERIALS AND METHODS

Applying a crossover study design, 70 healthy participants (35 women, 35 men) participated in our study. BRT was assessed using a custom-made driving simulator. We assessed BRT under six conditions: without a brace (control) (1), with a typical postoperative ankle brace with adjustable ROM and the settings: unrestricted (2), fixed at 15° (3) plantar flexion, restricted with 15°/50° (4) (dorsal/plantar flexion), a brace for ligament instabilities (5) and an elastic ankle bandage (6). Participants were instructed to apply the brake pedal exclusively with the right foot as quickly as possible on receipt of a visual stimulus.

RESULTS

The 70 participants showed significantly impaired BRT with the ankle brace for ROM restriction in the settings: unrestricted (p<0.001), fixed at 15° plantar flexion (p<0.001) and 15°/50° dorsal/plantar flexion (p<0.001) as compared to the control group. BRT was not impaired with the brace for ankle instabilities or the elastic ankle bandage.

CONCLUSIONS

In conclusion, right-sided ROM restricting ankle braces involve significant impairment of BRT in healthy participants. No such prolonged BRT was found for an elastic ankle bandage or the ligament brace.

Potential Mechanisms Leading to Overuse Injuries of the Back in Alpine Ski Racing: A Descriptive Biomechanical Study

BACKGROUND

Overuse injuries of the back are a common complaint among top athletes and of competitive alpine skiers in particular. However, there is limited understanding about the sport-specific causes of these injuries that is essential for their prevention.

PURPOSE/HYPOTHESIS

This study was undertaken to describe the sport-specific, overall trunk kinematics and skiers' loading during giant slalom turns and to assess the plausibility of the hypothesis that a combination of frontal bending, lateral bending, and/or torsion in the loaded trunk might be a potential mechanism leading to overuse injuries of the back in alpine ski racing.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eight European Cup-level athletes performed giant slalom runs with 2 different pairs of skis (varying in length, width, and sidecut). They were analyzed with respect to selected kinematic variables related to spinal disc loading. The overall trunk movement components (frontal bending, lateral bending, and torsion) were measured using 2 inertial measurement units fixed on the sacrum and sternum. Total ground-reaction forces were measured by pressure insoles.

RESULTS

During the turn phase in which the total ground-reaction forces were the greatest (up to 2.89 times the body weight), the highest average values of frontal bending (38.7°), lateral bending (14.7°), and torsion (7.7°) in the trunk occurred. Similar magnitudes were observed when skiing on longer, giant slalom skis with less width and sidecut.

CONCLUSION

The typical loading patterns of the back in alpine ski racing include a combined occurrence of frontal bending, lateral bending, and torsion in the loaded trunk. Because these factors are known to be related to high spinal disc loading, they may be considered important components of mechanisms leading to overuse injuries of the back in alpine ski racing.

CLINICAL RELEVANCE

Prevention measures should aim to control and/or reduce the magnitude of frontal bending, lateral bending, and torsion in the trunk, as well as the peak loads, while skiing.

Driving reaction time before and after surgery for disc herniation in patients with preoperative paresis

BACKGROUND CONTEXT

The effect of many types of surgeries on driving reaction time (DRT) has been reported. Although lumbar disc herniation is one of the most common spinal diseases, the effect on DRT has not been investigated.

PURPOSE

To assess the effect of left- and right-sided pareses caused by lumbar disc herniation on DRT before and after surgery.

STUDY DESIGN

Controlled prospective clinical trial.

PATIENT SAMPLE

Patients undergoing disc surgery.

OUTCOME MEASURES

Impact of paresis caused by lumbar disc herniation and disc surgery on DRT.

METHODS

Forty-two consecutive patients (mean age, 50.3 years) were tested for DRT 1 day before surgery, postoperatively before hospital discharge, and 5 weeks after surgery. Visual analogue scale (VAS) for back and leg pain as well as pain medication and patients' driving frequency were recorded.

RESULTS

Significant improvement of DRT after surgery was seen in patients with left- and right-sided pareses (p<.005). For the right-sided paresis group, the preoperative DRT was 761 ms (median, interquartile range [IQR]: 490), 711 ms (median, IQR: 210) immediately postoperatively, and 645 ms (median, IQR: 150) at follow-up (FU). For the left-sided paresis group, DRT was 651 ms (median, IQR: 270) preoperatively, 592 ms (median, IQR: 260) postoperatively, and 569 ms (median, IQR: 140) at FU. Significant differences between right- and left-sided pareses were identified preoperatively and at FU testing (p<.005). No correlation was found between VAS for leg or back pain and DRT. Historical control subjects had a DRT of 487 (median, IQR: 116), which differed significantly at all three test times (p<.001).

CONCLUSIONS

A significant reduction in DRT in patients with right- and left-sided pareses was found after surgery, indicating a positive effect of surgery. The improvement in DRT seen immediately postoperatively and the lack of a generally accepted threshold for DRT would suggest that for both patient samples, it is safe to continue driving after hospital discharge. However, patients should be informed accordingly.

Brake response time returns to the pre-surgical level 6 weeks after unicompartmental knee arthroplasty

PURPOSE

The objective of the study was to clarify whether driving abstinence should be recommended when patients are discharged from hospital after unicompartmental knee arthroplasty (UKA). We tested the hypotheses that there are differences in the peri-operative course of brake response time in patients undergoing right-sided (1) or left-sided (2) UKA. Additionally, we tested whether brake response time is significantly influenced by pain (3), driving experience (4) or age (5).

METHODS

In 43 patients undergoing UKA, brake response time was measured with a custom-made driving simulator pre-operatively and 1 and 6 weeks after UKA. Patients' visual analogue scales for knee pain and their self-reported driving experience were also assessed.

RESULTS

In patients with right-sided UKA, brake response time changed from 786 (261) ms pre-operatively to 900 (430) ms 1 week post-operatively (p = 0.029). At 6 weeks post-operatively, brake response time had returned to 712 (139) ms, which was deemed to be an insignificant change from the pre-operative reference benchmark. When surgery was performed on the contralateral left side, no effect was found onto the right side's brake response time. Knee pain and driving experience were significantly correlated with brake response time. No such correlations were found between brake response time and age.

CONCLUSIONS

On the basis of the current findings, it is concluded that brake response time returns to pre-operative levels 6 weeks after UKA surgery. Therefore, it is proposed that driving be abstained from for that period.

Driving reaction time before and after surgery for lumbar disc herniation in patients with radiculopathy

PURPOSE

Although patients scheduled to undergo lumbar disc surgery often ask when they are allowed to drive a motor vehicle again, there are no published recommendations on this subject.

METHODS

We conducted a prospective study in 46 consecutive patients (mean age 48.9 years) to determine driving reaction time (DRT) before and after surgery in patients with lumbar disc herniation. Of the patients 23 had left-side radiculopathy and 23 right-side radiculopathy. Driving reaction time as well as back and leg pain were evaluated preoperatively, on the day of discharge from hospital and at the 5-week follow-up examination (FU). 31 healthy subjects were tested as controls.

RESULTS

Significant improvement in DRT was seen for both patient samples (p < 0.05). For patients with a right-side radiculopathy preoperative DRT was 664 ms (median, IQR: 241), which was reduced to 605 ms (median, IQR: 189) immediately postoperatively and to 593 ms (median, IQR: 115) at FU. For patients with a left-side radiculopathy DRT was 675 ms (median, IQR: 247) preoperatively, 638 ms (median, IQR: 242) postoperatively and 619 ms (median, IQR: 162) at FU. Pain was moderately correlated to DRT. Control subjects had a driving reaction time of 487 (median, IQR: 116), which differed significantly from patients at all three testing times (p < 0.001).

CONCLUSION

Our data indicate a positive effect of the surgery on driving ability. Therefore, we would suggest that for both patient samples it is safe to continue driving after hospital discharge. However, patients have to be informed about increased DRT caused by radiculopathy already before surgery.

Impaction bone grafting

In revision total hip replacement, bone loss can be managed by impacting porous bone chips. In order to guarantee sufficient mechanical strength, the bone chips have to be compacted. The aim of this study was to determine in an in vitro simulation whether the use of a pneumatic hammer leads to higher primary stability than manual impaction. Bone mass characteristics were measured by force and distance variation of a penetrating punch, which was lowered into a plastic cup filled with bone chips. From these measurements bulk density, contact stiffness, impaction hardness and penetration resistance were calculated for different durations of impaction.

We found that the pneumatic method reached higher values of impaction hardness, contact stiffness and bulk density suggesting an increase in stability of the implant. No significant differences were found between the two different methods concerning the penetration resistance. The pneumatic method might reduce the risk of fracture in vivo, as force peaks are smaller and applied for a shorter period. Results from manual impaction showed higher variability and depend much on the experience of the surgeon. The pneumatic hammer is a suitable tool to standardise the impaction process.

Brake response time before and after total knee arthroplasty: a prospective cohort study

BACKGROUND

Although the numbers of total knee arthroplasty (TKA) are increasing, there is only a small number of studies investigating driving safety after TKA. The parameter 'Brake Response Time (BRT)' is one of the most important criteria for driving safety and was therefore chosen for investigation.The present study was conducted to test the hypotheses that patients with right- or left-sided TKA show a significant increase in BRT from pre-operative (pre-op, 1 day before surgery) to post-operative (post-op, 2 weeks post surgery), and a significant decrease in BRT from post-op to the follow-up investigation (FU, 8 weeks post surgery). Additionally, it was hypothesized that the BRT of patients after TKA is significantly higher than that of healthy controls.

METHODS

31 of 70 consecutive patients (mean age 65.7 +/- 10.2 years) receiving TKA were tested for their BRT pre-op, post-op and at FU. BRT was assessed using a custom-made driving simulator. We used normative BRT data from 31 healthy controls for comparison.

RESULTS

There were no significant increases between pre-op and post-op BRT values for patients who had undergone left- or right-sided TKA. Even the proportion of patients above a BRT threshold of 700 ms was not significantly increased postop. Controls had a BRT which was significantly better than the BRT of patients with right- or left-sided TKA at all three time points.

CONCLUSION

The present study showed a small and insignificant postoperative increase in the BRT of patients who had undergone right- or left-sided TKA. Therefore, we believe it is not justified to impair the patient's quality of social and occupational life post-surgery by imposing restrictions on driving motor vehicles beyond an interval of two weeks after surgery.

Proximal humeral fractures: what is semi-rigid? Biomechanical properties of semi-rigid implants, a biomechanical cadaver based evaluation

INTRODUCTION

Proximal humerus fractures remain challenging especially in the elderly. Biomechanical data put semi-rigid implants in favour of osteopenic or osteoporotic situation. Little surgical side damage is associated with a minimal invasive approach of these implants. The aim of this study was to evaluate the mechanical properties of three such implants.

MATERIAL AND METHODS

Fresh frozen cadaver specimens were mounted as proposed by the distributors. Three different implants were used: LCP-PH (locking compression plate proximal humerus, Synthes, Austria), HB (humerus block, Synthes, Austria), and IMC (intramedullary claw, ITS, Austria). Subcapital fracture was simulated by resecting a 5 mm gap. All specimens were comparable in "B" (one), "M" (ineral) and "D" (ensity). Four load cases were tested: varus bending, medial shearing and axial torque. A cyclic test (1,000 cycles) was performed in the first load case (varus stress) for all three implants.

RESULTS

The LCP-PH was the most rigid in all three load cases, always followed by the HB. The IMC was the most elastic device with almost immeasurable values in axial torque. In the cyclic setting, the load reduction of the HB followed by the LCP-PH was significantly better than that for the IMC.

CONCLUSION

The differences in stiffness are varying tremendously. The IMC is the implant with the lowest stiffness in all load cases and the highest load reduction. New "semi-rigids" claim good clinical performance, yet prospective clinical studies have to prove this. It is unlikely that the IMC can maintain fracture reduction in fracture situations of complex nature (no ligamentotaxis).

Modified Prusik knot versus whipstitch technique for soft tissue fixation in anterior cruciate ligament reconstruction: a biomechanical analysis

Appropriate graft tension and secure graft incorporation in bone tunnels are essential for successful anterior cruciate ligament (ACL) reconstruction using hamstring tendon autografts. Permanent viscoplastic elongation in response to cyclic loading in the early postoperative period and the interposition of suture material in the tendon-bone interface might negatively affect graft function and rigid graft incorporation in the bone tunnels. A modified Prusik knot is an alternative option to the commonly used whipstitch technique for soft tissue fixation in ACL reconstruction. This is a controlled laboratory study. Sixteen formalin-fixed human cadaver semitendinosus tendons were armed with a modified Prusik knot or a whipstitch and tested in a load-to-failure test with a constant displacement rate of 1 mm/s, 14 in the cyclic loading test with 100 cycles from 10 to 50 N followed by 100 cycles from 10 to 75 N. The modified Prusik knot showed smaller force-induced displacements and higher stiffness of the entire construct in the load-to-failure test. Smaller preconditioning displacements were the only significant differences in the cyclic loading test. The modified Prusik knot has equal or superior mechanical properties and provides a larger area in the tendon-bone interface without suture material compared with the whipstitch technique.

Decrease in eccentric hamstring strength in runners in the Tirol Speed Marathon

BACKGROUND

The local muscular endurance of knee flexors, during eccentric work in particular, is important in preventing or delaying kinematic changes associated with fatigue during treadmill running. This result, however, may not be transferable to overground running.

OBJECTIVE

To test the hypothesis that overground running is associated with eccentric hamstring fatigue.

METHODS

Thirteen runners (12 male and one female) performed an isokinetic muscle test three to four days before and 18 hours after a marathon. Both legs were tested. The testing protocol consisted of concentric and eccentric quadriceps and hamstring contractions.

RESULTS

There were no significant differences between peak torque before and after the race, except that eccentric peak hamstring torque (both thighs) was reduced.

CONCLUSION

Overground running (running a marathon) is associated with eccentric hamstring fatigue. Eccentric hamstring fatigue may be a potential risk factor for knee and soft tissue injuries during running. Eccentric hamstring training should therefore be introduced as an integral part of the training programme of runners.

[Therapy for static scapholunate instability -- reconstruction of the dorsal part of the scapholunate ligament with a periosteal flap of the iliac crest]

Recurrent instability is frequent following capsulodesis, tenodesis, or ligament reconstruction in static scapholunate instability. Therefore a periosteal flap of the iliac crest was designed to reconstruct the dorsal part of the SL ligament, which is known to be the biomechanically strongest portion and also the axis of rotation between the scaphoid and lunate. Biomechanical testing of ten fresh frozen dorsal SL ligaments and ten periosteal flaps of the iliac crest showed similar properties concerning failure force, failure displacement, failure stress, energy to failure and stiffness. Results of eight specimens in each group were available following successful testing. Failure force of the dorsal SL ligament was 171.8 N (SD 44.2), energy to failure amounted 269.1 N-mm (SD 98.9), failure stress was 10.3 N/mm (2) (SD 1.3), failure displacement 2.9 mm (SD 0.4), and stiffness 77.2 N/mm (SD 21.4). Testing of the periosteal flap gave the following values: failure force 144.3 N (SD 38.7), energy to failure 217.9 N-mm (SD 85.0), failure stress 9.9 N/mm (2) (SD 1.7), failure displacement 3.0 mm (SD 0.4) and stiffness 60.5 N/mm (SD 14.7). In addition to these test values, clinical and radiological data of eleven patients were available following reconstruction of the dorsal SL ligament with a periosteal flap of the iliac crest. The interval between trauma and surgery was 15 months, mean follow-up was 29 months. One patient was free of pain, whereas ten mentioned pain during or following strenuous work. Two patients were completely satisfied, nine complained about some restriction during special activities. Active range of motion amounted to 56 degrees extension, 46 degrees flexion, 17 degrees radial abduction, 30 degrees ulnar abduction. Grip strength was 38.5 kg, which was 79 % of the contralateral side. Radiological evaluation demonstrated a correction of the static instability in nine cases. In two patients recurrence of static instability was obvious. The prerequisite for success of the procedure is the easy reduction of the carpals. In cases of a fixed rotatory subluxation of the scaphoid, the technique cannot maintain the reduction.

P-Match: transcription factor binding site search by combining patterns and weight matrices

P-Match is a new tool for identifying transcription factor (TF) binding sites in DNA sequences. It combines pattern matching and weight matrix approaches thus providing higher accuracy of recognition than each of the methods alone. P-Match is closely interconnected with the TRANSFAC^® database. In particular, P-Match uses the matrix library as well as sets of aligned known TF-binding sites collected in TRANSFAC^® and therefore provides the possibility to search for a large variety of different TF binding sites. Using results of extensive tests of recognition accuracy, we selected three sets of optimized cut-off values that minimize either false negatives or false positives, or the sum of both errors. Comparison with the weight matrix approaches such as Match™ tool shows that P-Match generally provides superior recognition accuracy in the area of low false negative errors (high sensitivity). As familiar to the user of Match™, P-Match also allows to save user-specific profiles that include selected subsets of matrices with corresponding TF-binding sites or user-defined cut-off values. Furthermore, a number of tissue-specific profiles are provided that were compiled by the TRANSFAC^® team. A public version of the P-Match tool is available at .

Is restoring regenerative potential a way to prevent anthracycline cardiotoxicity? A hypothesis

Anthracycline-induced cardiotoxic effects are a serious problem among young patients who survive childhood cancer and there is an urgent need to avoid such effects. It is generally accepted that the only effective way to do this is to prevent cardiac injury during chemotherapy. There are several possible ways to do this, though questions remain. Evidence suggests the existence of a resident population of self-renewing cardiac stem cells capable of contributing to heart repair. Cardiac stem cells have an intrinsically poor regenerative response to heart injury. However, recent results point to ways to enhance the formation of cardiac precursor cells necessary for regeneration after injury. Moreover, the results of a recent study demonstrated that activation of the Notch signaling pathway, well characterized for its role in myogenesis and tissue formation during embryogenesis, restores impaired regenerative potential of skeletal muscle by activating resident precursor cells (satellite cells), which have a markedly impaired propensity to proliferate and to produce the myoblasts necessary for muscle regeneration. Based on these findings, and because the mechanisms behind the cardiotoxic effects of anthracyclines are not fully understood and current ways to avoid anthracycline-induced cardiotoxic effects have limitations, we hypothesize herein that an attractive way to avoid these effects may be to promote repair and regeneration, as opposed to prevent injury (e.g. by dexrazoxane).

Scapholunate ligament reconstruction using a periosteal flap of the iliac crest: a biomechanical study

INTRODUCTION

Advances continue to improve direct reconstruction of the dorsal scapholunate (SL) ligament, which is the strongest part of the entire SL ligament and is known as the turning point between the scaphoid and lunate. This study was designed to compare the biomechanical properties of the dorsal SL ligament with those of a periosteal flap of the iliac crest, which is a new graft candidate for dorsal SL reconstruction.

MATERIALS AND METHODS

A bone-ligament-bone complex was harvested for biomechanical testing from the iliac crest and the dorsal SL complex. Ten specimens could be prepared in each group. After potting the bone blocks in methylmethacrylate for stable fixation, the specimens were tested, using a servohydraulic testing system, at a rate of 10 mm/min.

RESULTS

Failure displacement, failure force, failure stress, energy to failure, and stiffness were assessed for both groups. Eight specimens in each group were tested successfully. In the ligament group, six specimens failed at the ligament level, whereas two failed at the insertion of the scaphoid. In the periosteum group, all eight specimens failed at the ligament level. The failure force of the dorsal SL ligament averaged 171.8 N, failure stress was 10.3 N/mm2, and failure displacement amounted to 2.9 mm. Energy to failure was 269.1 N-mm, and stiffness averaged 77.2 N/mm. Failure force of the periosteal flap amounted to 144.3 N, failure stress was 9.9 N/mm2, failure displacement was 3.0 mm, and energy to failure was 217.9 N-mm. Stiffness of the periosteal flap measured 60.5 N/mm. Comparison of the dorsal SL ligament and the periosteal flap of the iliac crest revealed no significant biomechanical differences.

CONCLUSION

Therefore, the biomechanical properties of the periosteal flap recommend its use for reconstruction of the dorsal SL ligament.

Excessive heat generation during cutting of cement in the Robodoc hip-revision procedure

The ROBODOC system is a promising new method for removing cement with high-speed milling. Heat is generated during the milling process. This study was designed to measure temperatures in the cutting area, and to assess the risk of heat injury and the effectiveness of irrigation. We measured temperatures at the bone-cement cutting area in three experimental settings, two involving the proximal area comprising a cement mantle, and one the distal cement plug beneath the prosthesis. Without cooling facilities, a mean temperature of 94 degrees C was measured in proximal areas. However, this could effectively be reduced below 70 degrees C with irrigation. In the area of the distal cement plug, we measured a mean temperature of 172 degrees C without irrigation. In this area, the integrated irrigation system with an additional high-flow irrigation system could not guarantee cooling to an acceptable temperature of below 70 degrees C since the irrigation stream was impeded by the cutter in the narrow cavity. We need an integrated irrigation device that guarantees continuous cooling at the cutting interface in front of the cutter.

Effect of a prosthetic disc nucleus on the mobility and disc height of the L4-5 intervertebral disc postnucleotomy

OBJECT

Current procedures for treatment of degenerative disc disease may not restore flexibility or disc height to the intervertebral disc. Recently, a prosthetic device, intended to replace the degenerated nucleus pulposus, was developed. In this biomechanical in vitro test the authors study the effect of implanting a prosthetic nucleus in cadaveric lumbar intervertebral discs postnucleotomy and determine if the flexibility and disc height of the L4-5 motion segment is restored.

METHODS

The prosthetic disc nucleus device consists of two hydrogel pellets, each enclosed in a woven polyethylene jacket. Six human cadaveric lumbar motion segments (obtained in individuals who, at the time of death, were a mean age of 56.7 years) were loaded with moments of +/- 7.5 Nm in flexion-extension, lateral bending, and axial rotation. The following states were investigated: intact, postnucleotomy, and after device implantation. Range of motion (ROM) and neutral zone (NZ) measurements were determined. Change in disc height from the intact state was measured after nucleotomy and device implantation, with and without a 200-N preload.

CONCLUSIONS

Compared with the intact state (100%), the nucleotomy increased the ROM in flexion-extension to 118%, lateral bending to 112%, and axial rotation to 121%; once the device was implanted the ROM was reduced to 102%, 88%, and 90%, respectively. The NZ increased the ROM to 210%, lateral bending to 173%, and axial rotation to 107% after nucleotomy, and 146%, 149%, 44%, respectively, after device implantation. A 200-N preload reduced the intact and postnucleotomy disc heights by approximately 1 mm and 2 mm, respectively. The original intact disc height was restored after implantation of the device. The results of the cadaveric L4-5 flexibility testing indicate that the device can potentially restore ROM, NZ, and disc height to the denucleated segment.

Creatine kinase, myosin heavy chains and magnetic resonance imaging after eccentric exercise

The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase (P < 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase (P < 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration (P< 0.01) as well as an increase in creatine kinase (P < 0.01). We suggest that changes in MRI T, signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres.

Motion in lumbar functional spine units during side bending and axial rotation moments depending on the degree of degeneration

STUDY DESIGN

Human lumbar spine specimens were tested in axial rotation and side bending. Motion was related to the grade of degeneration.

OBJECTIVES

To determine the degree to which degeneration with fissure formation in the disc affects axial rotation of the lumbar functional spine unit.

SUMMARY OF BACKGROUND DATA

There is controversy in the literature regarding the influence of severe degeneration and fissures of the disc on the range of axial rotation.

METHODS

Thirty-six lumbar spine specimens were tested in axial rotation and side bending, by applying pure moments in an unconstrained setting. The motion in 6 df was recorded by dial gauges. The grade of degeneration was established by the grading schemes of Nachemson, Thompson, Adams, and Mimura.

RESULTS

A significant increase of axial rotation and lateral translation under torque was found. This increase mainly took place between Grade 3 according to the schemes of Nachemson, Thompson, and Adams (no fissure formation) and the higher grades of degeneration (defined by fissure formation). Reduced disc height was always associated with fissures.

CONCLUSIONS

A reduced lumbar disc height in radiographs seems to be associated with fissure formation in the disc. In this case, the range axial rotation after torque is increased in comparison with cases with less degeneration.

Effects of specimen length on the monosegmental motion behavior of the lumbar spine

STUDY DESIGN

An in vitro biomechanical analysis of the segmental motion behavior of the same segments in polysegmental (five segments), bisegmental, and monosegmental specimens using sheep lumbosacral spines.

OBJECTIVES

To investigate the effect of specimen length on monosegmental motion behavior. These data may be helpful in planning in vitro tests and in comparing results of studies using specimens of different lengths.

SUMMARY OF BACKGROUND DATA

The length of spinal specimens used for in vitro stability tests varies greatly, depending on the purpose of the study. Some investigators prefer testing specimens with one adjacent segment on either end of the region of interest. Others favor specimens as short as possible.

METHODS

In a first step, seven sheep spine specimens, L3-S1 (note that sheep spines normally have seven lumbar vertebrae), each were tested without preload in a spine-loading apparatus. Alternating sequences of pure lateral bending, flexion/extension, and axial rotation moments (+/-3.75 Nm) were applied continuously. The motion in each single segment was measured simultaneously. Then, these polysegmental specimens were cut into two bisegmental specimens, L3-L5 and L6-S1, and tested in the same way. Finally, another vertebra was removed to obtain two monosegmental specimens, L3-L4 and L7-S1, and to test them as described.

RESULTS

In general, the range of motion at L3-L4 and L7-S1 was smaller when tested in polysegmental than in monosegmental specimens. In polysegmental specimens (five segments), the range of motion at L3-L4 and L7-S1 was approximately 80% (range, 70.6-92.5%) and in bisegmental specimens approximately 95% (range, 66.7-100%) of their range of motion measured in monosegmental specimens. Neutral zone and coupled motions showed the inverse behavior. Significant differences were found. However, they were not consistent with either the loading direction or with the specimen length.

CONCLUSIONS

For comparison of results, the specimen length should be kept constant within one experiment. Segmental motion behavior of specimens with different lengths should be compared only qualitatively.

Measuring forces and frequency during active compression decompression cardiopulmonary resuscitation: a device for training, research and real CPR

Active compression decompression (ACD) cardiopulmonary resuscitation (CPR) is possibly a superior alternative to standard (STD) CPR, but an optimal compression and decompression pattern has to be ensured. ACD-CPR can be evaluated during CPR training sessions using commercially available manikins; however devices for recording compression and decompression forces or frequency during real CPR are lacking. Using the Ambu CardioPump without changing its mechanical characteristics, two force transducers were integrated into the ACD device. Using specially designed electronics and a portable computer, compression and decompression forces were measured and displayed continuously and compression frequency and the compression decompression phase are calculated on-line during real CPR action. All measured parameters were stored on a hard disk for later retrieval and analysis. Linearity of force measurement was better than 6% within a -250- +500 N range. The error in repeatability was below 5% thus outperforming the original mechanical force measurement system of the Ambu CardioPump. Compression frequency was calculated very accurately (error < 1%). The system has been successfully used during CPR training, during ACD-CPR in 37 corpses under research conditions and in five out-of-hospital CPR casualties. Simple and safe in use, our modified CardioPump with integrated electronics provides an important, technically advanced solution for monitoring ACD-CPR on-line. It warrants quality assurance during ACD-CPR training and in real CPR scenarios and guarantees accurate recording of compression and decompression forces and compression frequency.

Measurement of vertebral rotation: a comparison of two methods based on CT scans

This study compared Ho's and Aaro's method to measure vertebral axial rotation in order to find the more accurate one. Two hundred fifty-nine CT scans were taken from 11 cadaver vertebrae. The scans were performed with vertebrae in neutral position and angulated up to 20 degrees in the sagittal and frontal plane to simulate kyphosis/lordosis and side bending. Axial rotation was measured according to both methods. The mean difference between true and measured values was 3.7 +/- 6.7 (95% confidence limit) (Ho's method) and 2.3 +/- 3.7 (Aaro's method), respectively. Correlation with true axial rotation was r2 = 0.66 (Ho's method) and r2 = 0.77 (Aaro's method). We recommend using Aaro's method as the more accurate measure of axial rotation in scoliotic vertebrae.

The prediction of failure of the stem in THR by measurement of early migration using EBRA-FCA. Einzel-Bild-Roentgen-Analyse-femoral component analysis

We report the ten-year results for three designs of stem in 240 total hip replacements, for which subsidence had been measured on plain radiographs at regular intervals. Accurate migration patterns could be determined by the method of Einzel-Bild-Roentgen-Analyse-femoral component analysis (EBRA-FCA) for 158 hips (66%). Of these, 108 stems (68%) remained stable throughout, and five (3%) started to migrate after a median of 54 months. Initial migration of at least 1 mm was seen in 45 stems (29%) during the first two years, but these then became stable. We revised 17 stems for aseptic loosening, and 12 for other reasons. Revision for aseptic loosening could be predicted by EBRA-FCA with a sensitivity of 69%, a specificity of 80%, and an accuracy of 79% by the use of a threshold of subsidence of 1.5 mm during the first two years. Similar observations over a five-year period allowed the long-term outcome to be predicted with an accuracy of 91%. We discuss the importance of four different patterns of subsidence and confirm that the early measurement of migration by a reasonably accurate method can help to predict long-term outcome. Such methods should be used to evaluate new and modified designs of prosthesis.

Effects of prolonged strenuous endurance exercise on plasma myosin heavy chain fragments and other muscular proteins. Cycling vs running

BACKGROUND

This study evaluates creatine kinase, myosin heavy chain, and cardiac troponin blood levels following three types of exercise: 1) short-distance uphill or downhill running; 2) alpine ultramarathon; and 3) alpine long-distance cycling.

METHODS

EXPERIMENTAL DESIGN

Comparative field study; follow-up up to 10 days.

SETTING

Department of Sports Medicine. All biochemical markers were analysed at the Department of Medical Chemistry and Biochemistry.

PATIENTS OR PARTICIPANTS

Subjects included healthy, trained males (N = 53). All subjects were nonsmokers and free from medication prior to and during the study. Each volunteer was an experienced runner or cyclist, who had at least once successfully finished the Swiss Alpine Marathon of Davos or the Otztal-Radmarathon before.

INTERVENTIONS

Running or cycling.

MEASURES

Plasma concentrations of creatine kinase, myosin heavy chain fragments and cardiac troponins were measured to diagnose skeletal and cardiac muscle damage, respectively.

RESULTS

Skeletal muscle protein release is markedly different between uphill and downhill running, with very little evidence for muscle damage in the uphill runners. There is considerable muscle protein leakage in the ultramarathoners (67 km distance; 30 km downhill running). In contrast, only modest amounts of skeletal muscle damage are found after alpine long-distance cycling (230 km distance).

CONCLUSIONS

This study proves that there is slow-twitch skeletal muscle fiber damage after prolonged strenuous endurance exercise and short-distance downhill running. Exhaustive endurance exercise involving downhill running and short-distance downhill running lead to more pronounced injury than strenuous endurance exercise involving concentric actions. From our results there is no reason for suggesting that prolonged intense exercise may induce myocardial injury in symptom-less athletes without cardiac deseases.

Muscular adaptation and strength during the early phase of eccentric training: influence of the training frequency

We investigated the effects of different training frequencies on maximum isometric voluntary contraction (MVC) force and plasma concentrations of muscle proteins during the early phase of eccentric training. MVC and plasma concentrations of creatine kinase (CK) and slow-twitch skeletal (cardiac beta-type) myosin heavy chain (MHC) fragments were measured before and 4 and 7 d after performing the first and last training task. Training tasks, which comprised 70 high-force eccentric contractions involving the thigh muscles (single leg), were performed under supervision in three groups (A, B, C) at the beginning and at the end of the study period (7 wk). In addition, groups A (N = 10) and B (N = 10) trained during the study period starting 1 wk after the first training task. Group A performed one training task once a week for 5 wk and group B (N = 10) twice a week for 2 wk and three times a week during the subsequent 3 wk. In all three groups the first training task resulted in delayed CK and MHC peaks and decrements in MVC, which were comparable (P > 0.05). Only training regimen B resulted in a significant increase in the MVC. Compared with the first training task training regimens, A and B significantly (P < 0.01) reduced the increase in serum muscle protein and muscle function impairment. The responses to the last training task did not differ significantly between groups A and B. In group C the responses after the second training task did not differ significantly from those observed after the first task. Our results suggest that, compared with group A, additional eccentric exercise in group B is the essential basis for the increase in muscle strength during the early phase of eccentric training without further benefits for muscular adaptation. In group C we found no muscular adaptation.

Review of active compression-decompression cardiopulmonary resuscitation (ACD-CPR). Analysis of iatrogenic complications and their biomechanical explanation

Our review takes a critical look at the active compression-decompression technique (ACD) for cardiopulmonary resuscitation (CPR). ACD-CPR was developed following a report of successful resuscitation performed by a medical amateur using a household plunger. The efficacy of the principle of active decompression has been demonstrated by animal and human studies. Potential iatrogenic complications from the CardioPump were evaluated only when large clinical trials were already underway. Our prospective analysis of autopsy patients and systematic randomised studies in corpses prove that ACD-CPR using the CardioPump considerably increases the rate of iatrogenic complications and especially of sternum fractures. The experimental use of the CardioPump in corpses and the analysis of a variety of different parameters, especially of the rubber cushion pads mounted in the silicone cup to prevent skin abrasions, revealed a statistically significant correlation between sternum fractures and female sex (P < 0.01) and usage of the rubber cushion pad (P = 0.045). Biomechanical studies showed that the transmission of forces from the CardioPump is greatly dependent on chest shape. The lower the sternum is sunken compared with the surrounding structures, the higher the force which is transmitted via the central area of the device onto the sternum. The rubber cushion pad shortens the distance between CardioPump and sternum by 5 mm and therefore increases the sternal loading. Sex differences in the shape of the sternum and especially the thickness may account for the significant correlation between sternum fractures and female sex.

Active compression-decompression resuscitation: the influence of different chest geometries on the force transmission

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) is performed using a plunger-like suction device applied onto the chest. Forces are partly transferred through the center of this device as well as through the peripheral ring of the plunger's lip seal. We analysed the load transmission distribution of the Ambu CardioPump; therefore a homemade mechanical model was used for simulating different chest geometries. We applied compression forces up to 750N on the device using a 'material testing machine', and we determined the load transferred through the central part of the device and the peripheral ring respectively. The results show that the deeper the sternum is inbeded in the chest the more force is distributed onto the peripheral ring of the plunger's vacuum cup. For a simulated flat chest, 70 N was transferred through the peripheral ring; at a simulated sternal depression of 20 mm, more than 300 N were transferred peripherally. This study points out that different chest geometries have to be considered when using CardioPump.

[Biomechanics of lumbar instability]

Several authors have tried to define segmental lumbar instability. Their definitions: increased antero-posterior translation, pathologic coupled motion, increased neutral zone, pathologic instantaneous center of rotation describe some mechanic findings occurring in the aging spine. However, there is no evidence that they help to differentiate the pathologic entity of segmental lumbar instability from the normal aging process. Dynamic explanation models are promising but at the moment they cannot be used clinically for diagnosis of instability as well. The most important structure to maintain lumbar stability is the intervertebral disc. In the third and fourth decade, more than 50 percent of specimen show peripheral tears of the anulus. It was shown in animal experiments that these tears develop to radial tears, which are accompanied by nuclear volume loss and decreased height. The facets degenerate one or two decades later. Corresponding with the loss of discal function, they increasingly contribute to spinal stability. In conclusion, the concept of lumbar segmental instability is not very helpful in clinical practise. It is recommended to base the decision of lumbar fusion on a painful degenerated disc, and additional findings promising a good result.

Comparison between single-screw and triangulated, double-screw fixation in anterior spine surgery. A biomechanical test

STUDY DESIGN

The advantage to fixation strength of triangulated, double-screw fixation compared with that of single-screw instrumentation in anterior spine surgery was evaluated by in vitro testing.

OBJECTIVES

To compare the fixation strength of single-screw instrumentation with ventral derotation spondylodesis screws with the fixation strength of triangulated, double-screw instrumentation with Cotrel-Dubousset-Hopf screws. Resistance against pull-out load and against load perpendicular to the axis of the screws was evaluated. To avoid the bias caused by different screw design, the pull-out strength of single screws of both devices was compared first.

SUMMARY OF BACKGROUND DATA

To the authors' knowledge, no study comparing anterior single with triangulated screws has been published.

METHODS

A pull-out test was performed when one vertebra in each spine specimen was instrumented with a ventral derotation spondylodesis screw, one with an isolated Cotrel-Dubousset-Hopf screws, and one with two triangulated, Cotrel-Dubousset-Hopf screws linked by a Cotrel-Dubousset-Hopf block. Load perpendicular to the axis of the screw was applied on the bone-device interface after instrumentation of further specimens with ventral derotation spondylodesis and triangulated, Cotrel-Dubousset-Hopf devices.

RESULTS

Use of isolated Cotrel-Dubousset-Hopf screws compared with ventral derotation spondylodesis screws showed no significant differences in pull-out strength. The use of triangulated, double-screw fixation with Cotrel-Dubousset-Hopf screws led to a significant 79% increase in resistance against pull-out and a 73% increase in resistance against load perpendicular to the screw axis compared with the resistance produced using ventral derotation spondylodesis single-screw instrumentation.

CONCLUSION

In anterior surgery, fixation of the vertebra-device interface can be improved considerably by application of two triangulated screws.

The contribution of anulus fibers to torque resistance

STUDY DESIGN

Anulus fibers of the intervertebral disc oriented in one direction were dissected, and oppositely directed fibers were left intact as a result of a newly developed dissection method. Motion segments were dissected by this way, and motion segments after bilateral facetectomy were loaded in torsion and compared with each other.

OBJECTIVES

To assess the contribution of facets and anulus fibers to torque resistance.

SUMMARY OF BACKGROUND DATA

Mathematical models predict that torsional stress is transmitted only to those collagene fibers of the anulus that are angled in the direction of the applied torque. Torsion and forward bending or torsion and compression are likely to cause anulus damage. No experimental study that we are aware of has confirmed that anulus fibers are the main structure to resist against torque.

METHODS

Pure axial rotation moments were applied on 12 lumbar motion segments. The six components of motion were recorded. Six motion segments were investigated intact after dissection of anulus fibers directed in one direction and after additional bilateral facetectomy. In six motion segments, bilateral facetectomy was performed before anulus dissection.

RESULTS

With the application of an axial rotation moment of 8.5 Nm to the left, axial rotation increased 2 degrees after dissection of disc fibers in one direction, and 1.2 degrees after bilateral facetectomy (P = 0.002). In the opposite direction, there were no differences. After both injuries, axial rotation was 7.6 degrees to the left (direction of fiber dissection) and -3.3 degrees to the right (P = 0.0005).

CONCLUSION

In lumbar motion segments without degeneration, anulus fibers restrict axial rotation more than the facets.

Biomechanical properties of the human tibia: fracture behavior and morphology

Standardized biomechanical dynamic load tests were performed to obtain fundamental information on the fracture behavior and morphology of the human tibia. After preparation, the specimens (n = 32) were loaded to breakage by ventral (one side alternately), dorsal, medial or lateral loading on a servo-hydraulic testing machine (Walter und Bai, Löhningen, Switzerland). Primary and secondary fracture lines and fissures were marked differently on the three surfaces of the tibia specimens. They were then videoscanned and digitized on a flatbed scanner to give two-dimensional fracture-line images. Load limits were 2475 to 12,206 Newton. The study revealed both direct fracture patterns with the fracture lines originating from the opposite site of impact, and indirect fracture patterns originating from the distal third of the specimens. Direct fractures occurred in 46% of the specimens after ventral loading, in 80% after medial or lateral loading, and in 100% after dorsal loading. Ventral, medial or lateral loading frequently produced direct wedge fractures of the Messerer type. Dorsal loading resulted in different direct patterns characterized by transverse fractures with longitudinal fissures at the impact site of the loading stamp. Direct transverse fractures also often showed a wedge-shaped pattern due to additional fissures. These were, however, identifiable only after maceration of the specimens and should receive closer attention in forensic practice.

The possibility of creating lordosis and correcting scoliosis simultaneously after partial disc removal. Balance lines of lumbar motion segments

STUDY DESIGN

The feasibility of correcting scoliosis and creating lordosis simultaneously in the thoracolumbar and lumbar spine by anterior instrumentation was investigated by in vitro testing.

OBJECTIVES

To evaluate the vertebral zones in which a compressive load applied in a motion segment creates side bending and lordosis in intact motion segments and after partial disc removal.

SUMMARY OF BACKGROUND DATA

Most investigators have observed a kyphogenic effect of anterior scoliosis instrumentation and recommended dorsal placement of screws and the use of wedge grafts, although wedge grafts were not used routinely by all surgeons.

METHODS

Zones of lordosization and side bending were determined by evaluation of balance lines between extension-flexion and side bending, respectively, by axial loading on ligamentous human motion segments with intact discs and after partial disc removal.

RESULTS

In lumbar motion segments with intact discs, it is possible to achieve ipsilateral side bending and lordosization by anterior instrumentation. After partial disc removal, the balance line between extension and flexion runs through the ipsilateral pedicle, and, therefore, a compressive load between the vertebral bodies always creates kyphosis.

CONCLUSIONS

After partial disc removal, it is not possible to create lordosis and correction of scoliosis simultaneously by ipsilateral anterior instrumentation without the use of intervertebral wedge grafts.

[Determination of back shape in median sagittal plane using an inclination sensory]

The measurement and assessment of the shape of the human back is in the process of becoming an important area of research. Various measuring techniques have already been developed, including moiré topography, stereoscopic photography and raster stereography. These have been employed in the evaluation of scoliosis, kyphosis, funnel chest and other pathological conditions of the spine. These systems are very complicated (and expensive) since they involve a three-dimensional analysis of the shape of the back. For preventive medical purposes, however, evaluation of the spine in the median sagittal plane alone often suffices. In this study, the inclinations of the back along the spine were measured, and it has been shown that these measurements can be used to reconstruct the shape of the back.

Axial rotation measurement of scoliotic vertebrae by means of computed tomography scans

STUDY DESIGN

This study evaluated the preconditions for exact axial rotation measurement and the possibility for other parameters to measure axial rotation and mechanical torsion.

OBJECTIVES

Quality criteria for axial rotation measurement in computed tomography scans are not established yet. Criteria should be found to improve axial rotation measurement.

SUMMARY OF BACKGROUND DATA

To the authors' knowledge, no systematic analysis of the errors of axial rotation measurement based on computed tomography scans has been performed.

METHODS

Axial rotation was measured in 259 computed tomography scans of 11 cadaveric vertebrae from scoliotic specimens. The sagittal axial rotation measurement angle of Aaro and Dahlborn and a new rotation parameter were measured with a pencil and ruler. Five landmarks were digitized and consequently five axial rotation parameters were computed. The influence of insufficient visualization of bony landmarks, mechanical torsion of the vertebra itself, and oblique position of the vertebra was evaluated.

RESULTS

Accuracy is considerably improved in central computed tomography scans (same distance to the top and bottom of the vertebral body) due to good visualization of landmarks and reduction of effects of mechanical torsion. The oblique vertebral position causes more errors. One mechanical torsion parameter with sufficient reliability is identified.

CONCLUSION

The sagittal axial rotation measurement method of Aaro and Dahlborn is superior to other techniques of measurement. It can be improved considerably if computed tomography scans fulfill certain quality criteria.

Rapid adaptation to eccentric exercise-induced muscle damage

This study examined eccentric exercise-induced muscle damage and rapid adaptation. Twenty-two male subjects performed 70 eccentric actions with the knee extensors. Group A (n = 11) and group B (n = 11) repeated the same exercise 4 and 13 days after the initial bout, respectively. Criterion measures included muscle soreness, muscle force generation (vertical jump height on a Kistler platform), and plasma levels of creatine kinase (CK), slow-twitch skeletal (cardiac beta-type) myosin heavy chains (MHC), and cardiac troponin I. Subjects were tested pre-exercise and up to day 4 following each bout. The initial exercise resulted in an increase in CK and MHC, a decrement in muscle force, and delayed onset muscle soreness in all participants. CK and MHC release correlated closely (rho = 0.73, p = 0.0001), both did not correlate with the decrement in muscle force generation after exercise. Because cardiac troponin I could not be detected in all samples, which excluded a protein release from the heart (cardiac beta-type MHC), this finding provides evidence for a injury of slow-twitch skeletal muscle fibers in response to eccentric contractions. Repetition of the initial eccentric exercise bout after 13 days (group B) did not cause muscle soreness, a decrement in muscle reaction force with vertical jump or significant changes in plasma MHC and CK concentrations, whereas in case of repetition after 4 days (group A) only the significant increases in CK and MHC were abolished. The decrement in reaction force with vertical jump did not differ significantly from that after the initial exercise session, but perceived muscle soreness was less pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Light concentric exercise and heavy eccentric muscle loading: effects on CK, MRI and markers of inflammation

The consequences of a single bout of heavy eccentric exercise with and without repeated concentric exercises on MRI images, serum CK levels and markers of inflammation were studied. Two groups (ECC and ECCON), each consisting of 18 male volunteers, performed 70 eccentic contractions of the quadriceps femoris muscle. The study group (ECCON) performed additional concentric contractions on a dynamometer (Cybex II+) one day before and two hours, 1, 2, 3, 6 and 9 days after eccentric loading. Serum levels of creatine kinase (CK) were examined as a function of time, and correlated with measurements of magnetic resonance imaging (MRI) of the involved muscle groups. T2-weighted images of the thigh muscles were studied. Serum C-reactive protein, complement factors C3c and C4, haptoglobin and transferrin were measured as markers of inflammation. Additional concentric contractions (ECCON group) significantly increased CK, compared to the ECC group. However, it has no apparent effect on MRI signal intensity changes, which were of equal magnitude in the loaded vastus intermedius and deep parts of the vastus lateralis in both groups. Likewise, the serum markers of inflammation of the exercised muscles appeared to be absent. Based on MRI-images, additional concentric contractions had no statistically significant effect on muscle damage and breakdown of connective tissue. The five-fold increase in CK in the ECCON group could be a reflection of "massaging out" of the CK from the muscles into the circulation by additional concentric exercises. However, it could also be an indication for a superior sensitivity of assessing muscle fiber damage in comparison to the MRI.