Michael Kraus

Can Computer-assisted Surgery Reduce the Effective Dose for Spinal Fusion and Sacroiliac Screw Insertion?

BackgroundThe increasing use of fluoroscopy-based surgical procedures and the associated exposure to radiation raise questions regarding potential risks for patients and operating room personnel. Computer-assisted technologies can help to reduce the emission of radiation; the effect on the patient’s dose for the three-dimensional (3-D)-based technologies has not yet been evaluated.Questions/purposesWe determined the effective and organ dose in dorsal spinal fusion and percutaneous transsacral screw stabilization during conventional fluoroscopy-assisted and computer-navigated procedures.Patients and MethodsWe recorded the dose and duration of radiation from fluoroscopy in 20 patients, with single vertebra fractures of the lumbar spine, who underwent posterior stabilization with and without the use of a navigation system and 20 patients with navigated percutaneous transsacral screw stabilization for sacroiliac joint injuries. For the conventional iliosacral joint operations, the duration of radiation was estimated retrospectively in two cases and further determined from the literature. Dose measurements were performed with a male phantom; the phantom was equipped with thermoluminescence dosimeters.ResultsThe effective dose in conventional spine surgery using 2-D fluoroscopy was more than 12-fold greater than in navigated operations. For the sacroiliac joint, the effective dose was nearly fivefold greater for nonnavigated operations.ConclusionCompared with conventional fluoroscopy, the patient’s effective dose can be reduced by 3-D computer-assisted spinal and pelvic surgery.Level of Evidence Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

One year orthopaedic trauma experience using an advanced interdisciplinary hybrid operating room

Hybrid operating rooms have been used successfully in several surgical specialties, but no data have been published for orthopaedic trauma. We present our one-year orthopaedic trauma experience using a hybrid operating room, which incorporates 3D fluoroscopic imaging as well as navigation capabilities. Data were compiled for a series of 92 cases performed in an advanced hybrid operating room at the level one trauma center in Ulm, Germany. All patients who had surgery performed using this operating room during the first year were included. Setup time and surgical complications using hybrid operating room were recorded and analysed. The hybrid operating room resulted in no higher rate of complication than expected from the same cases in a conventional operating room. The hybrid room did however allow the surgeon to confidently place implants for orthopaedic trauma cases, and was most advantageous for spine and pelvis cases, both minimally invasive and conventional. Further, appropriate reduction and implant position was confirmed with 3D imaging prior to leaving the operating room and obviated the need for postoperative CT scan. Based on our one-year experience, the hybrid operating room is a useful and safe tool for orthopaedic trauma surgery.

A prospective randomized controlled trial comparing occupational therapy with home-based exercises in conservative treatment of rotator cuff tears

BACKGROUND This pilot study evaluates the outcome after occupational therapy, compared to home-based exercises in the conservative treatment of patients with full thickness rotator cuff tears. METHODS Forty-three adult subjects (range, 18-75 years), who had a full thickness rupture of the rotator cuff which was verified by magnetic imaging tomography, with clinical signs of a chronic rotator cuff impingement, and who were available for follow-up, were randomized to occupational therapy or to independent home-based exercises using a booklet. After drop-out, 38 patients were available for full examination at follow-up. Before therapy and after 2 months of conservative treatment, pain intensity, the Constant-Murley score, isokinetic strength testing in abduction and external rotation, functional limitation, clinical shoulder tests and health-related quality of life (EQ-5D) were evaluated. RESULTS Two-thirds of the patients improved in clinical shoulder tests, regardless of the therapy group. There were no significant differences between the groups with reference to pain, range of motion, maximum peak force (abduction, external rotation), the Constant-Murley score, and the EQ-5D index. The only significant difference observed was the improvement in the self-assessed health- related quality of life (EQ-5D VAS) favoring home-based exercises. CONCLUSION Home-based exercise, on the basis of an illustrated booklet with exercises twice a day, supplies comparable results to formal occupational therapy in the conservative treatment of rotator cuff tears. The results of this pilot study suggest some potential advantages related to psychological benefits using home-based treatment.

The effect of both a thoracic trauma and a soft-tissue trauma on fracture healing in a rat model

Background and purpose There is some clinical evidence that fracture healing is impaired in multiply injured patients. Nothing is known, however, about the effects of various types of injuries and their contribution to a possible disturbance of the fracture-healing process. We investigated the effect of a thoracic trauma and an additional soft-tissue trauma on fracture healing in a rat tibia model. Methods 3 groups of rats were operated: group A with a simple fracture of the tibia and fibula, group B with a fracture and an additional thoracic trauma, and group C with a fracture, thoracic trauma, and an additional soft-tissue trauma. The fracture and the soft-tissue injury were produced by a special guillotine-like device and the thoracic trauma by a blast wave generator. After one day, the serum level of IL-6 was quantified, and at the end of the study (28 days) the mechanical properties and the callus volume of the healed tibia were determined. Results Increasing the severity of the injury caused IL-6 levels to more than double 1 day after injury. It halved the load to failure in mechanical tests and led to reduced callus volume after 28 days of healing. Interpretation Fracture healing is impaired when additional thoracic trauma and soft tissue trauma occurs.

Integration of fluoroscopy-based guidance in orthopaedic trauma surgery – A prospective cohort study

INTRODUCTION Computer-assisted guidance systems are not used frequently for musculoskeletal injuries unless there are potential advantages. We investigated a novel fluoroscopy-based image guidance system in orthopaedic trauma surgery. MATERIALS AND METHODS The study was a prospective, not randomised, single-centre case series at a level I trauma centre. A total of 45 patients with 46 injuries (foot 12, shoulder 10, long bones seven, hand and wrist seven, ankle seven and spine and pelvis four) were included. Different surgical procedures were examined following the basic principles of the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF). Main outcome measurements were the number of trials for implant placement, total surgery time, usability via user questionnaire and system failure rate. RESULTS In all cases, the trajectory function was used, inserting a total of 56 guided implants. The system failed when used in pelvic and spinal injuries, resulting in a total failure rate of 6.5% (n=3) of all included cases. The overall usability was rated as good, scoring 84.3%. CONCLUSION The novel image-guidance system could be integrated into the surgical workflow and was used successfully in orthopaedic trauma surgery. Expected advantages should be explored in randomised studies.

Therapy Recommendation “Act as Usual” in Patients with Whiplash Injuries QTF I°

Up to now no therapy study has used the classification system of the Quebec Task Force (QTF) to differentiate between patients with (QTF II°) and without functional disorders (QTF I°). This differentiation seems meaningful, as this difference may be relevant for the correct treatment planning. In this context the effect of the therapy recommendation “act as usual” has been evaluated in a homogeneous patient collective with whiplash injuries QTF I°. 470 patients with acute whiplash injuries had been catched in this study and classified according to the QTF. 359 patients (76.4%) with QTF I° injuries could be identified. Out of that 162 patients were enrolled to the study and received the therapy recommendation “act as usual” and the adapted pain treatment with non-steroidal anti-inflammatory drugs (NSAID). After six months the outcome was evaluated by phone. After injury the median pain score assessed by a visual analogue scale (VAS) was 5.4 (min = 3.3; max = 8.5). After six months 5 of the 162 patients complained intermittent pain symptoms (VAS values < 2). This is consistent with a chronification rate of 3.1%. After injury, the median pain disability index (PDI) was 3.9 (min = 1.9; max = 7.7). After six months 3 of the 162 patients stated persisting disability during sporting and physical activities (VAS values < 1). The therapy recommendation “act as usual” in combination with an adapted pain treatment is sufficient. Usually patients with whiplash injuries QTF I° do not need physical therapy. An escalation of therapy measures should be reserved to patients with complicated healing processes.

Muscle activity influence on the kinematics of the cervical spine in frontal tests

Objective: The question of muscle activity influence on the cervical spine kinematics during rear-end and frontal crash events has been discussed. Less data are available concerning frontal collisions. Therefore, the objective of this study was to investigate the influence of the ventral and dorsal neck muscles on the cervical spine kinematics during simulated frontal sled collisions. Methods: A frontal collision with a velocity change (delta V) of 10.2 km/h was simulated in a sled test with 10 healthy subjects (7 female; 3 male). A high-speed camera and accelerometers recorded the motion and acceleration data. The activity of the sternocleidomastoid muscles was recorded with surface electrodes. To avoid cross-talk, an intramuscular recording of the semispinalis capitis muscles was performed with fine-wire electrodes. Results: The sequence of both muscle activities was reproducible in all subjects. The maximal force of the sternocleidomastoid muscle was observed after a median of 152 ms, with 0 defining the time of the trigger signal. With earlier onset of muscle force, maximal dorsal horizontal acceleration of the head (r = −0.600) was reached later and the ventral translation (r = −0.733) and flexion movement (r = −0.755) set in earlier. The maximal force of the semispinalis capitis muscle was observed after a median of 160 ms. If the duration of muscle force was longer, the maximal head flexion (r = 0.685) and the maximal ventral head translation (r = 0.738) were reached later. Conclusions: The sternocleidomastoid muscle force is mainly associated with the horizontal head acceleration and influences the onset of the flexion and translation motion. To summarize, these temporal correlations allow the conclusion that the semispinalis capitis muscle force is mainly associated with the angular head acceleration and influences the duration of the flexion and translation motion.

Image guidance can support scaphoid K-wire insertion: an experimental study and initial clinical experience

PurposeIn the treatment of small bone fractures, such as the scaphoid bone, conventional navigation is limited by its dependence on fixed reference arrays. We introduce a new technique based on reference markers in surgical instruments. If visible on a standard fluoroscopic image, static trajectories are overlaid in this image to guide implant insertions. Fixed markers are not required. The purpose of this study was to identify the possible advantages of the new guidance technique.MethodsFor this study, 20 artificial hand specimens were randomized into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. We used a clip containing radiopaque markers, which was detected by the system’s workstation. A static trajectory was displayed consecutively in the fluoroscopic image to serve as an aiming device. Secondly, we included 3 patients with fractures of the scaphoid bone to test the integrability of this novel method in a clinical setting.ResultsIn the experimental setup, trajectory guidance reduced the duration of surgery and radiation exposure. Furthermore, it reduced the perforation rate. Accuracy was not improved by the new technique. For clinical cases, the system was integrated into the accommodated surgical workflow and rated as very helpful by users.ConclusionThe system helped reduce the misplacement rate and the emission of radiation. The main limitations were that trajectories were not displayed in real time and could only be shown in a single fluoroscopic image. However, the system is simple and can be easily integrated into the surgical workflow.

Muscle Activity Influence on the Kinematics of the Cervical Spine in Rear-End Sled Tests in Female Volunteers

Objective: Although much research has been performed to investigate the cervical spine kinematics during rear-end collisions, our understanding about the exact role of the musculature is limited. The question of the influence of muscle activity on cervical spine kinematics has been discussed. Methods: A rear-end collision with a speed change (ΔV) of 6.3 km/h was simulated in a sled test with 8 female subjects to investigate the influence of the ventral and dorsal cervical spine musculature on cervical spine kinematics. A high-speed camera and accelerometers recorded the motion and acceleration data. The activity of the sternocleidomastoid muscles was recorded with surface electrodes. To avoid cross talk, an intramuscular recording of the semispinalis capitis muscles was performed with fine-wire electrodes. Results: The analysis of the motion and acceleration parameters allowed the definition of 4 phases. The headrest contact began after a median of 84 ms and the sternocleidomastoid muscle force could be detected after a median of 81 ms, with 0 defining the time of the trigger signal. The maximal force of the sternocleidomastoid muscle and the maximal headrest effect began prior to the maximal ventral angular head acceleration and prior to the maximal ventral horizontal head acceleration relative to T1. The start of the semispinalis capitis muscle force was observed after a median of 159 ms and increased until a flexion of 20 to 25° was reached. Conclusions: The headrest effect and the sternocleidomastoid muscle force firstly supported the deceleration of the head relative to T1 toward dorsal, which was followed by an accelerating effect toward ventral. The semispinalis capitis muscle force exerted a late decelerating effect on head flexion and ventral translation movement.

Navigated treatment of metatarsal V fractures using a new image based guidance system.

Computer assisted imaging systems are rarely used for fracture treatment and foot surgery. We introduce a new system for image based guidance in traumatology.