Lars Grossterlinden

Comparison of open versus percutaneous pedicle screw insertion in a sheep model

Minimally invasive surgery has become more and more important for the treatment of traumatic spine fractures. Besides, some clinical studies, objective data regarding the possible lower damage to the surrounding tissue of the spine is still missing. Here we report a sheep model where we compared a percutaneous versus an open approach for dorsal instrumentation with pedicle screws to the spine. Twelve skeletally mature sheep underwent bilateral pedicle screw fixation at the L4–L6 level. Forty-eight pedicle screws were bilaterally inserted into the pedicles and connected with rods using either an open dorsal standard or a percutaneous approach. Operation time, blood flow, compartment pressure, radiation time, loss of blood, laboratory findings and EMG were evaluated to objectify possible advantages for the percutaneous operation technique. Loss of blood and the distribution of CK-MM as a marker for muscle damage were significantly lower in the percutaneous group. However, radiation time was significantly longer in the percutaneous group. Other parameters like compartment pressure, blood flow and also measurement of the EMG at different time points did not reveal significant differences. Based on the results we found in the present study, percutaneous screw insertion can bring moderate advantages but it should be noted that essential functional deficits to the muscle could not be detected.

Antegrade nailing of humeral head fractures with captured interlocking screws.

Objectives/Design: To assess the functional outcome after treatment of proximal humeral fractures with a new antegrade nail that provides angular and sliding stability. Intervention/Patients: Ninety-seven patients were treated during a 4-year period between April 2000 and March 2004. All patients were followed for 6 months, 51 patients (53%) for 12 months, and 31 patients (32%) for 24 months. This study focuses mainly on the patients with a follow up of 1 year. Their mean age was 68 years (range: 33 to 90); 22% were more than 80 years of age. Main Outcome Measurements: All fractures were radiologically graded by the Neer and AO/ASIF classifications. Clinical assessment was performed at all follow-up visits using the Constant-Murley and Neer scores, and complications were recorded. Results: There were 26.8% 2-part, 66% 3-part, and 7.2% 4-part fractures. The relative Constant-Murley score improved significantly (P < 0.001) from 72% at 6 months to 82% at 12 months after operation. No further improvement regarding functional outcome was observed after 24 months. Patients younger than 60 years of age had better results. No significant functional differences were found among 2-, 3- or 4-part fractures. Complications included backing out of the proximal screws (9.8%), secondary dislocation (1.9%), complete osteonecrosis (1.9%), and partial osteonecrosis (5.8%). Conclusion: Treatment with this nail provides sufficient fixation of the fragments to allow early mobilization. The good functional results in the majority of the patients indicate that this nail can be used, even in complex fractures and elderly patients.

Biomechanical Evaluation for Mechanisms of Periprosthetic Femoral Fractures

BACKGROUND There are a number of biomechanical tests for various treatment options of periprosthetic femoral fractures, but different loading modalities prelude their direct comparison. This study was designed to develop an experimental model of osteoporotic bone fractures near the femoral stem that is based on a simple testing protocol to increase the reproducibility. In addition, we wanted to clarify whether a femoral prosthetic stem reduces the femoral fracture strength. METHODS Twenty human cadaveric femurs were harvested, and five groups were randomized on the basis of the bone mineral density using a pQCT device. The specimens of three groups were provided with a cemented Exeter V40 stem and loaded to failure with torsion (I), anterior (II), and lateral load (III). The femurs of groups IV and V remained uninstrumented and were tested in a four-point bending assay similar to groups II and III. All biomechanical testings were realized with a servohydraulic testing machine (MTS). RESULTS There was no significant difference regarding bone mineral density of all groups. Torsional testing generated proximal intertrochanteric fractures and anterior loading resulted exclusively in supracondylar fractures. Introducing the force from the lateral side, all fracture lines occurred close to the tip of the stem, similar to a Vancouver-B fracture. Assuming that lateral load application is a main responsible mechanism of periprosthetic femoral fracture near the tip of the stem, the fracture strength of instrumented femurs was significantly reduced (group III: 4,692 N vs. group V: 6,931 N; p < 0.05). CONCLUSION Prosthetic stems reduce femoral fracture strength significantly. In an osteoporotic bone model, a four-point bending test with lateral load application seems to be a suitable approach.

Internal fixation of femoral neck fractures with posterior comminution: A biomechanical comparison of DHS® and Intertan nail®

Background and purposeInternal fixation is a therapeutic mainstay for treatment of undisplaced femoral neck fractures and fractures without posterior comminution. The best treatment for unstable and comminuted fractures, however, remains controversial, especially in older patients. The present study was designed to assess the utility of the Intertan Nail® (IT) for stabilization of comminuted Pauwels type III fractures compared to dynamic hips screw (DHS).MethodsRandomized on the basis of bone mineral density, 32 human femurs were assigned to four groups. Pauwels type III fractures were osteomized with a custom-made saw guide. In 16 specimens the posteromedial support was removed and all femurs were instrumented with an IT or a DHS. All constructs were tested with nondestructive axial loading to 700N, cyclical compression to 1,400N (10,000 cycles), and loading to failure. Outcome measures included number of survived cycles, mechanical stiffness, head displacement and load to failure.ResultsPostoperative mechanical stiffness and stiffness after cyclical loading were significantly reduced in all constructs regardless of the presence of a comminution defect (p = 0.02). Specimens stabilized with the IT had a lower construct displacement (IT, 8.5 ± 0.5 mm vs. DHS, 14.5 ± 2.2 mm; p = 0.007) and sustained higher failure loads (IT, 4929 ± 419 N vs. DHS, 3505 ± 453 N; p = 0.036) than the DHS constructs.InterpretationIn comminuted Pauwels type III fractures, the fixation with the IT provided sufficient postoperative mechanical strength, comparable rate of femoral head displacement, and a similar tolerance of physiological loads compared to fractures without comminution. The absence of the posteromedial support in comminuted fractures tended to reduce the failure load regardless of the fixation method.

Factors influencing the accuracy of iliosacral screw placement in trauma patients

Correct placement of iliosacral screws remains a surgical challenge. The aim of this retrospective study was to identify parameters which impact the accuracy of this technically demanding procedure. Eighty-two patients with vertically unstable pelvic injuries treated with a total of 147 iliosacral screws were included. Assessment of postoperative CT scans revealed screw misplacement in 13 cases (8%), of which six occurred following insertion of two unilateral screws into S1. Six screw misplacements occurred in patients with dislocation injuries of the posterior pelvis. Comparison of a navigated and the standard technique revealed a decreased screw misplacement rate in the navigated group (15% standard vs. 3% navigation, p < 0.05). In addition, the malposition rate was influenced by the surgeon’s individual experience (20% for low vs. 3.9% for high volume surgeons, p < 0.05). Overall, the accuracy of iliosacral screw placement depends on the number of screws inserted into S1 and the extent of dislocation. In experienced hands, the use of navigation represents a helpful tool to improve the placement accuracy.

Determination of Femoral Neck Angle and Torsion Angle Utilizing a Novel Three-Dimensional Modeling and Analytical Technology Based on CT Datasets.

Introduction Exact knowledge of femoral neck inclination and torsion angles is important in recognizing, understanding and treating pathologic conditions in the hip joint. However, published results vary widely between different studies, which indicates that there are persistent difficulties in carrying out exact measurements. Methods A three dimensional modeling and analytical technology was used for the analysis of 1070 CT datasets of skeletally mature femurs. Individual femoral neck angles and torsion angles were precisely computed, in order to establish whether gender, age, body mass index and ethnicity influence femoral neck angles and torsion angles. Results The median femoral neck angle was 122.2° (range 100.1–146.2°, IQR 117.9–125.6°). There are significant gender (female 123.0° vs. male 121.5°; p = 0.007) and ethnic (Asian 123.2° vs. Caucasian 121.9°; p = 0.0009) differences. The median femoral torsion angle was 14.2° (-23.6–48.7°, IQR 7.4–20.4°). There are significant gender differences (female 16.4° vs. male 12.1°; p = 0.0001). Femoral retroversion was found in 7.8% of the subjects. Conclusion Precise femoral neck and torsion angles were obtained in over one thousand cases. Systematic deviations in measurement due to human error were eliminated by using automated high accuracy morphometric analysis. Small but significant gender and ethnic differences were found in femoral neck and torsion angles.

3D fluoroscopic navigated reaming of the glenoid for total shoulder arthroplasty (TSA).

Survival rates for total shoulder arthroplasty are critically dependent on the correct placement of the glenoid component. Especially in osteoarthritis, pathological version of the glenoid occurs frequently and has to be corrected surgically by eccentric reaming of the glenoid brim. The aim of our study was to evaluate whether eccentric reaming of the glenoid can be achieved more accurately by a novel computer assisted technique. Procedures were conducted on 10 paired human cadaveric specimens presenting glenoids with neutral version. To identify the correction potential of the navigated technique compared to the standard procedure, asymmetric reaming of the glenoid to create a version of −10° was defined as the target. In the navigated group, asymmetric reaming was guided by a 3D fluoroscopic technique. Postoperative 3D scans revealed greater accuracy for the eccentric reaming procedure in the navigated group compared to the freehand group, resulting in glenoid version of −9.8 ± 3.8° and −5.1 ± 4.1°, respectively (p < 0.05). Furthermore, deviation from preoperative planning was significantly reduced in the navigated group. These data indicate that our navigated procedure offers an excellent tool for supporting glenoid replacement in TSA.

Management of traumatic spinopelvic dissociations: review of the literature

PurposeSpinopelvic dissociation is a rare high-energy injury pattern in adults associated with high morbidity and an increased rate of neurological deficits. The purpose of this article is the conception of fracture type-associated treatment recommendations.MethodsThis article is based on our own experience with spinopelvic dissociations and a review of the current literature.ResultsBilateral vertical plus an optional transverse fracture component configures spinopelvic dissociations as “U”- or “H”-shaped, with the result of a spinopelvic dissociation. “Y”-, “T”- or “II”-shaped fractures do not necessarily belong to this entity but can be subsumed to this entity in a wider sense. The surgical treatment of these injuries remains challenging. Initial haemodynamic stabilisation represents the main goal of primary care until definitive treatment can be performed. Anatomical reduction is demanding and even more complex in fracture areas with large comminution. Surgical treatment options depend on the fracture type, including transsacral screws, sacral banding and spinopelvic fixation, plus combinations of these procedures.ConclusionsSpinopelvic dissociations remain highly complex injuries. “U”- and “H”-shaped fractures usually require triangular fixation, whereas “II”-, “Y”- and “T”-shaped fractures might be sufficiently stabilised with transsacral screws.

Foudroyant Course of an Extensive Clostridium septicum Gas Gangrene in a Diabetic Patient with Occult Carcinoma of the Colon

Background. Spontaneous gas gangrene is a rare disease in which Clostridium septicum frequently can be detected. After an incubation period of 5–48 hours, a very painful swelling is accompanied by a rapidly spreading toxic-infectious clinical picture ultimately leading to septic shock and multiple organ failure. We present a case of a completely documented rare infectious disease with triage findings including initial vital signs, initial medical findings, and the emergency lab., radiological, intraoperative, histopathological, microbiological, and postmortem results. After initial diagnosis of the underlying disease, the patient has been immediately transferred to the operating theatre. The laboratory findings reflect the devastating effect of toxin α which is a toxin typically produced by C. septicum. The patient presented both an anaemia and a manifest coagulopathy as well as an onset of multiple organ failure. Despite the aggressive medical and surgical measures that have been taken, this patient could not be saved. Discussion. The case presented vividly emphasises the difficulty to identify these cases early enough to save a patient. This documentation may help health care providers to identify this life threatening disease as early as possible in future cases.

Proximal Humeral Fractures: Nailing

Treating proximal humeral fractures surgically has always been a challenge for the orthopaedic trauma surgeon. The challenge was and is due to numerous factors such as the specific anatomy of the proximal humerus, problems of an adequate approach and exposure of the fracture and different fracture fragments, possible iatrogenic injuries to the rotator cuff on approach and the detrimental effects of the former on the latter’s gliding and contracting ability after surgery. Furthermore, the very different fracture patterns that can occur at the proximal humerus, the shear number of fragments which can be of extremely bad bone quality, the necessity for anatomic reduction of these fragments with an implant that will allow for a stable osteosynthesis and at the meantime will not impinge in the subacromial area and lastly, the intention of the physician-in-charge to commence with physical therapy as soon as possible post OP. All of these added to the fact that not one fixation technique with one certain implant could be recommended as a treatment or implant of choice in dealing with these difficult fractures. Most of the supposedly applicable surgical techniques and implants had major setbacks such as being limited to only very expert hands, necessitating a long-standing postoperative immobilisation, resulting in secondary loosening of implants, secondary loosening of reduction or impaired bone healing and, despite all efforts, finally led to poor function at the shoulder. With the advent of angular stable implants such as angular stable, anatomically contoured plates designed for proximal humeral fractures only and special angular stable nails for the same or similar indications the treatment options and the quality of treatment in this area was much improved. Our experience with angular stable nails of two different manufacturers in now more than 320 implantations reveals that indications for the surgical treatment of such fractures can be extended constantly, that the number of complications will simultaneously decline, the necessity for primary joint arthroplasty even in multiple fragment fractures is minimal and that long-term results are, comparing the published results in the literature with those of our institution, equal if not superior to other treatment options.