Superior outcomes of decompression with an interlaminar dynamic device versus decompression alone in patients with lumbar spinal stenosis and back pain: a cross registry study.

INTRODUCTION: Surgical decompression for lumbar spinal stenosis (LSS) has been associated with poorer outcomes in patients with pronounced low back pain (LBP) as compared to patients with predominant leg pain. This cross registry study assessed potential benefits of the interlaminar coflex® device as an add-on to bony decompression alone. METHODS: Patients with lumbar decompression plus coflex® (SWISSspine registry) were compared with decompressed controls (Spine Tango registry). Inclusion criteria were LSS and a preoperative back pain level of ≥5 points. 1:1 propensity score-based matching was performed. Outcome measures were back and leg pain relief, COMI score improvement, patient satisfaction, complication, and revision rates. RESULTS: 50 matched pairs without residual significant differences but age were created. At the 7-9 months follow-up interval the coflex® group had higher back (p=0.014) and leg pain relief (p<0.001) and COMI score improvement (p=0.029) than the decompression group. Patient satisfaction was 90% in both groups. No revision was documented in the coflex® and one in the decompression group (2.0%). DISCUSSION: In the short-term, lumbar decompression with coflex® compared with decompression alone in patients with LSS and pronounced LBP at baseline is a safe and effective treatment option that appears beneficial regarding clinical and functional outcomes. However, residual confounding of non-measured covariables may have partially influenced our findings. Also, despite careful inclusion and exclusion of cases the cross registry approach introduces a potential for selection bias that we could not totally control for and that makes additional studies necessary.

Moments and forces during pedicle screw insertion. In vitro and in vivo measurements.

STUDY DESIGN: Moments and forces during pedicle screw insertion were measured in vivo and in vitro and were correlated to several parameters of the screw-bone interface. OBJECTIVES: To compare the in vitro and in vivo screw insertion loads and to relate these measurements to bone mineral density, pedicle size, and other screw parameters (material, diameter). SUMMARY OF BACKGROUND DATA: The in vitro screw insertion torque has been correlated to the screw pullout forces and the number of cycles to ultimate interface failure. However, there are no comparable in vivo data. METHODS: One hundred three pedicle screws were included in the study, 43 in vivo and 60 in vitro. Duel-energy x-ray absorptiometry boen mineral density data were available for 20 in vivo and 32 in vitro specimens. A custom-made sterilizable six-axis load cell was integrated into a torque wrench, enabling the recording of the applied moments and forces during screw insertion. Statistical analysis was performed to detect differences and correlations. RESULTS: The mean in vivo insertion torque (1.29 Nm) was significantly greater than the in vitro value (0.67 Nm). The linear correlation between insertion torque and bone mineral density was significant for the in vitro data but not for the in vivo data. No correlation was observed between insertion torque and pedicle diameter. Two patterns of torque were observed during the insertion process. CONCLUSIONS: There is a significant difference between the insertion loads measured in vivo and those measured in vitro. Additional research is needed to verify whether this method provides an indication of screw fixation quality.

Image-guided insertion of transpedicular screws. A laboratory set-up.

STUDY DESIGN: A computer-assisted system allowing precise preoperative planning and real-time intraoperative image localization of surgical instruments is tested in a laboratory setup. OBJECTIVES: The purpose of this study is to assess the applicability, functionality, and accuracy of this transpedicular spinal fixation technique. SUMMARY OF BACKGROUND DATA: Most techniques in transpedicular spinal fixation rely on the identification of predefined targets with the help of anatomic landmarks and on the intraoperative use of image intensifiers. Various studies report considerable screw misplacement rates which may lead to serious clinical sequelae such as permanent nerve damage. METHODS: The proposed system was tested in an in vitro setup drilling 20 pedicle pilot holes in lumbar vertebrae. The accuracy was assessed using precision cuts through the pedicles and simulation of a 6-mm pedicle screw insertion. RESULTS: An ideal screw position was found in 70 of 77 cuts, and in no case was an injury to the pedicular cortex observed. CONCLUSIONS: The presented technique provides a safe, accurate, and flexible basis for transpedicular screw placement in the spine. This approach should be further evaluated in clinical applications.

Accuracy of computer-assisted pedicle screw placement. An in vivo computed tomography analysis.

STUDY DESIGN: A computer-assisted planning and visualization system (the Orthopaedic Surgery Planning System) was tested for pedicle screw insertion in vivo. OBJECTIVES: To evaluate the system's applicability for regular intraoperative use and its accuracy for pedicle screw placement in vivo. SUMMARY OF BACKGROUND DATA: Pedicle screw placement poses considerable anatomic and biomechanical risks. The reported rates of screw misplacement with conventional insertion techniques are unacceptably high. It previously has been shown in vitro that computer assistance offers the potential to decrease the number of screws perforating the pedicular cortex. METHODS: The accuracy of 162 pedicle screws inserted with the Orthopaedic Surgery Planning System was assessed by means of postoperative computed tomography evaluation. Reconstructions of the horizontal, frontal, and sagittal planes were analyzed. Cortex perforations were graded in steps of 2 mm. RESULTS: The cortex was perforated in 2.7% of pedicles. Complete preoperative computed tomography scanning of the levels to be operated on is essential to allow for a precise image reconstruction. Initial difficulties in applying the system contribute to the malplacements. A learning curve for general handling of the Orthopaedic Surgery Planning System was observed. CONCLUSIONS: The system provides a safe and reproducible technique for pedicle screw insertion. Other applications in the field of spine surgery are under evaluation.

Exercise-induced compartment syndrome in the flexor-pronator muscle group. A case report and pressure measurements in volunteers.

Compartment syndrome is caused by an increase in intracompartmental pressure above the capillary level, preventing capillary flow. The acute onset of symptoms occurs after events such as fracture, soft tissue trauma, and revascularization and usually necessitates prompt fasciotomy to avoid loss of function or even necrosis of the enclosed muscle. Compartment syndromes in athletes are of a recurrent nature and are usually referred to as chronic. Nonoperative treatment is often successful. Although compartment syndromes can occur in several anatomic regions, the most commonly seen in athletes involve the leg. Chronic compartment syndromes of the upper extremity are rare, and only a few cases have been reported in the literature. The intracompartmental pressures causing chronic symptoms in these cases ranged between 22 mm Hg at rest and 40 mm Hg after 30 minutes of exercise. Under maximal contraction, a pressure of 58 mm Hg has been recorded. The object of this paper is to report a case of a tennis player where much higher flexor-pronator muscle intracompartmental pressures than those noted above were recorded. We compared the intracompartmental pressure data of this patient with intracompartmental pressures measured in six symptom-free volunteers.

Adjacent vertebral failure after vertebroplasty. A biomechanical investigation.

Vertebroplasty, which is the percutaneous injection of bone cement into vertebral bodies has recently been used to treat painful osteoporotic compression fractures. Early clinical results have been encouraging, but very little is known about the consequences of augmentation with cement for the adjacent, non-augmented level. We therefore measured the overall failure, strength and structural stiffness of paired osteoporotic two-vertebra functional spine units (FSUs). One FSU of each pair was augmented with polymethylmethacrylate bone cement in the caudal vertebra, while the other served as an untreated control. Compared with the controls, the ultimate failure load for FSUs treated by injection of cement was lower. The geometric mean treated/untreated ratio of failure load was 0.81, with 95% confidence limits from 0.70 to 0.92, (p < 0.01). There was no significant difference in overall FSU stiffness. For treated FSUs, there was a trend towards lower failure loads with increased filling with cement (r2 = 0.262, p = 0.13). The current practice of maximum filling with cement to restore the stiffness and strength of a vertebral body may provoke fractures in adjacent, non-augmented vertebrae. Further investigation is required to determine an optimal protocol for augmentation.

Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis.

Surgical dislocation of the hip is rarely undertaken. The potential danger to the vascularity of the femoral head has been emphasised, but there is little information as to how this danger can be avoided. We describe a technique for operative dislocation of the hip, based on detailed anatomical studies of the blood supply. It combines aspects of approaches which have been reported previously and consists of an anterior dislocation through a posterior approach with a 'trochanteric flip' osteotomy. The external rotator muscles are not divided and the medial femoral circumflex artery is protected by the intact obturator externus. We report our experience using this approach in 213 hips over a period of seven years and include 19 patients who underwent simultaneous intertrochanteric osteotomy. The perfusion of the femoral head was verified intraoperatively and, to date, none has subsequently developed avascular necrosis. There is little morbidity associated with the technique and it allows the treatment of a variety of conditions, which may not respond well to other methods including arthroscopy. Surgical dislocation gives new insight into the pathogenesis of some hip disorders and the possibility of preserving the hip with techniques such as transplantation of cartilage.

Compression of the radial digital nerve of the thumb.

We report a case of digital nerve compression in the thumb caused by a fibrous band from flexor pollicis brevis to the sheath of flexor pollicis longus. After release of that band the patient was immediately symptom free.

The first twelve cases of computer assisted periacetabular osteotomy.

Image guided freehand navigation of surgical instruments has been applied to the Bernese periacetabular osteotomy, a complex surgical technique for the treatment of dysplastic hips. This navigation system has been introduced into the operating room and has so far been used for 12 patients. Image data from computed tomography (CT) scans are presented in various ways to support the preoperative plan and to provide optimized control of surgical action. Special attention has been paid to the implementation of a sophisticated surgeon-machine interface. This paper describes the features of this novel surgical navigation system and its introduction into the clinical environment.

Computer-assisted Orthopaedic surgery (AOS): from pedicle screw insertion to further applications.

Computer assisted orthopaedic surgery is a new but rapidly evolving field. Based on previous research and development in the area of stereotactic neuronavigation a few groups have adapted these technologies for the image interactive insertion of pedicle screws. The present paper summarizes past and current work in the field of computer assisted orthopaedic surgery and describes the state of the art of research and future innovations, particularly in in vivo applications.

Mechanisms of retrolisthesis in the lower lumbar spine. A radiographic study.

The study investigates lower lumbar segments with posterior vertebral shifts (retrolisthesis) with respect to the orientation of facet joints, disc height, lordosis of the lumbar spine, and orientation of vertebral endplates. Standing lumbar radiographs as well as CT and/or MRI investigations of 69 patients were analyzed. Data from patients with retrolisthesis (20 cases) were compared to data from patients with degenerative spondylolisthesis (DS, 23 cases), and from patients without signs of vertebral shifts (26 cases). The orientation of facet joints in segments with retrolisthesis was not different from segments without shifts, whereas the facet joints in patients with DS were oriented more sagittally. The overall lordosis of the lumbar spine and the endplate inclination were considerably reduced in patients with retrolisthesis, especially compared to those with DS. Disc height was comparable in retrolisthesis and DS, but was reduced compared to segments without shifts. The results support biomechanical considerations, that a retrolisthesis of a lower lumbar spine segment is correlated with a reduction of lumbar lordosis, endplate inclination, and segmental height.

[Surgical indication of ankle joint supination trauma?]. / Gibt es noch eine Operationsindikation nach Sprunggelenks-Supinationstraumata?

Even for severe ankle sprains the non-operative, functional treatment is the therapy of choice. The prognosis is good: persisting symptoms and instability are rare and the outcome seems to be independent of initial therapy. An indication for primary operation is an exception. In case of remaining symptoms the patient should be referred to an orthopedic surgeon for further diagnostic studies (MRI) and possibly secondary operative stabilization.

Degeneration of the cervical disc: histology compared with radiography and magnetic resonance imaging.

Decisions about the treatment of neck pain are largely made on the basis of information gained from plain X-rays and magnetic resonance imaging (MRI), which are used routinely as part of preliminary investigation. We performed a descriptive cadaveric study to compare histology with radiography and MRI. We correlated plain radiography, disc height [Farfan index (FI)] and MRI findings with histology to assess the ability of radiology to detect significant pathologic lesions. The study included 52 motion segments from nine subjects over the age of 50, who underwent routine hospital autopsy. Disc degeneration was assessed by histology, radiography, disc height (FI: anterior disc height plus posterior disc height divided by anterioposterior diameter) and MRI using established grading systems. Most of the discs were classified radiologically as grade 1 (19/52), grade 2 (13/52), grade 3 (9/52) or grade 4 (3/52). Eight of the discs were graded as normal. The distribution of MRI grades was grade 0 (9/36), grade 1 (9/36), grade 2 (7/36), grade 3 (8/36) and grade 4 (3/36). Half of the discs (26/52) showed advanced (grade 4) degeneration histologically. FI correlated with histological grade (P = 0.013), MRI grade (P = 0.02) and radiological grade (P < 0.001) of degeneration. Radiological and histological grade of degeneration showed a weak correlation (r = 0.3, P = 0.033). MRI correlated with overall histological grade (r = 0.41, P = 0.015, n = 34). Histological features (e.g., tears, rim lesions, prolapse of nucleus material) were poorly recognised by MRI, which had a sensitivity for disc material prolapse and annulus tears of less than 40%. Our study showed that discs from patients over 50 years are histologically severely degenerated; however, these changes may not be detected by conventional radiography and MRI.

Tenodesis of the long head of biceps brachii in the painful shoulder: improving results in the long term.

Fifteen shoulders of 14 patients with a keyhole tenodesis of the long head of the biceps were reviewed at an average follow-up of 7 years (3 years, 1 month to 13 years, 2 months). In 13 cases additional shoulder disease was noted during the operation. Eight patients had undergone rotator cuff decompression before the reference biceps tenodesis was performed. Eight (53%) cases achieved an excellent result; one was rated as good, four were rated as fair, and two had failures. Seven shoulders had an improved result from short to long term, and only two deteriorated. An upward migration of the humeral head on x-ray evaluation was noted but was without clinical significance. A local anesthetic test to the long head of the biceps before the operation seemed to be valuable in assessing chances of a good long-term result.

[Surgical therapy of radial head fracture--results of osteosynthesis and resection treatment]. / Die operative Therapie der Radiusköpfchenfraktur--Ergebnisse der Osteosynthesen und der Resektionsbehandlung.

Between 1982 and 1993 we performed internal fixation or resection in 95 adult patients for radial head fracture. It was possible to follow up 68 patients for an average of 2.1 years. In 53 cases the initial injury was an isolated radial head fracture, which was treated by internal fixation in 41 and resection in 12 cases. Good results were obtained in 80% of patients. A satisfactory outcome was associated with young age, little initial fragment dislocation, internal fixation with screw + K-wire, and early postoperative physiotherapy. Primary resection for crush fractures of the radial head did not have negative long-term effects. In a comparison group with complex elbow injuries (elbow luxation in 9 and a Monteggia-type injury in 6 cases) in addition, results were considerably poorer and did not depend on the above-mentioned factors.

Dens fractures in the elderly. Results of anterior screw fixation in 19 elderly patients.

Type 2 dens fractures in the elderly may be regarded as fragility fractures due to osteoporosis and are prone to nonunion with closed treatment. We investigated the outcome of direct anterior screw fixation of these fractures in 19 patients over 65 years of age. The type of injury, radiological appearance over time and the clinical outcome were analyzed, with an average follow-up of 4.5 years. Surgery and postoperative treatment were tolerated well in all patients. In 16 cases, bony union was achieved after 3-6 months. 2 pseudarthroses, which required no treatment, occurred. At follow-up, 15 patients had no symptoms. 10 of the patients had diminished rotation. We conclude that anterior screw fixation is a successful therapy in most cases of type 2 dens fractures in the elderly.

[Percutaneous cementing techniques in treatment of osteoporotic spinal sintering]. / Perkutane Zementierungstechniken zur Behandlung osteoporotischer Wirbelkörpersinterungen.

During the last years minimal-invasive augmentation techniques of vertebral bodies have been established to stabilize painful height losses. A vertebroplasty fills the vertebral body with cement, whereas a kyphoplasty intends to achieve a reduction of kyphosis prior to cementing. The present review describes both techniques and summarizes in vivo and in vitro experiences.

[Loss of correction after dorsal stabilization of burst fractures of the thoracolumbar junction. The role of transpedicular spongiosa plasty]. / Korrekturverlust nach dorsaler Stabilisierung von Berstungsfrakturen des thorakolumbalen Ubergangs. Die Rolle der transpedikulären Spongiosaplastik.

Short segment pedicle instrumentation for thoracolumbar burst fracture is known to fail due to lack of anterior support. Additional transpedicular grafting and dorsolateral fusion were offered to prevent its failure. The purpose of this study was to analyse the clinical and radiological outcome in two identical groups of patients treated with short segment pedicle instrumentation and posterolateral fusion with and without inter- and intracorporal transpedicular bone grafting. The clinical and radiological results of two identical groups of patients with thoracolumbar burst fractures were analysed. 15 patients (2 f, 13 m), mean age 35 years, were treated with bisegmental fixation with the fixateur interne and unisegmental fusion. Further 15 patients (3 f, 12 m), mean age 34 years, obtained additional intra- and intercorporal bone grafting. The implants were removed 15 resp. 13 months post surgery. Latest clinical and radiological follow-up was at 61/24 months. The clinical results were identical in both groups. Radiological measurements showed a significant loss of correction for all three measured angles (vertebral kyphosis, unisegmental kyphosis and bisegmental kyphosis) in both groups. However, patients with transpedicular bone grafting showed less loss of bony, vertebral kyphosis. Neither dorsolateral fusion nor dorsolateral fusion with transpedicular bone grafting could prevent loss of angular corrections.

Bone substitutes in vertebroplasty.

Vertebroplasty--percutaneous cement augmentation of vertebral bodies--is an efficient procedure for the treatment of painful vertebral fractures in osteoporosis. At the present time, polymethylmethacrylate (PMMA) is the only available cement with reports of clinical application and experience. The material is easy to handle, the radiopacity can be adapted by adding contrast dye, and it is mechanically efficient. Composite cements (acrylic cements in conjunction with ceramics) are bioactive, highly radiopaque, and feature excellent mechanical properties. One such cement, Cortoss, is currently undergoing clinical trials for vertebroplasty and has so far been shown to be a potentially valuable alternative to PMMA. Several in vitro studies with injectable calcium phosphate (CaP) cements show their feasibility and mechanical effectiveness. Animal studies confirm their biocompatibility and osteoconductivity. However, handling problems and the limited radiopacity of these cements currently preclude their clinical use.

[Percutaneous cementing techniques of the spine -- chances and limits]. / Perkutane Augmentierungstechniken der Wirbelsäulen. Möglichkeiten und Grenzen.

Vertebroplasty and Kyphoplasty represent minimal-invasive techniques for cement augmentation of vertebral bodies. Both procedures are successfully used for pain-relieving stabilizations of osteoporotic fractures or malignant processes. Advantages of kyphoplasty over vertebroplasty are to be seen in the possibility of deformity correction as well as in a decreased risk of cement extrusions which represent the most important potential for clinical complications. Long-term experiences with the effect of cementing are sparse. Thus it seems even more important, to judge indications and possibilities realistically. The decision whether and when to perform an augmentation is influenced by multiple factors. These include age of the patient, age of the fracture, degree of deformation and further degenerative changes of the spine. This article summarizes the present research and literature und is thought to provide guidelines for the aforementioned decision making processes.