Navigation in ACL reconstruction - comparison with conventional measurement tools

Restoration of rotational and translational stability is a goal of ACL reconstruction. Intraoperative instability measurements of AP translation and rotation are not well established clinically. We compared navigated measurements of tibial AP translation and rotation with mechanical measuring devices: the KT 1000 and a modified goniometer tool. Tests were repeated with intact and dissected ACLs, and measures of translation and rotation statistically compared. There was no significant difference in AP translation between navigation, 3.2 mm (range 1-6 mm) and the KT 1000, 4.8 mm (range, 4-7 mm) in our experimental set up (p>0.05). Tibial rotation revealed no significant difference, 0.12 degrees (range, 0 degrees -1 degrees ) between navigation and goniometer (p>0.05). Total range of rotation was 4.2 degrees (range, 2 degrees -6 degrees ) in intact and 7.05 degrees (range, 4 degrees -9 degrees ) in dissected ACLs (p<0.05). Stability parameters in ACL navigation can be measured precisely under laboratory conditions and results are not significantly different from mechanical testing devices.

Präzision in der orthopädischen Computernavigation

Navigation has become increasingly integrated into orthopaedic surgery, especially in the area of endoprosthetic procedures. Simplification of the instrumentation along with the use of imageless systems has increased the ease of use for the orthopaedic surgeon. Principle navigation systems enable an accuracy of corrections and alignments within intervals of 1 mm or 1 degrees . Consequently, potential intra- and interobserver failures during the registration procedure typically range within a few millimetres or degrees. Analysis of the actual algorithms used for the registration process of the lower extremity mechanical axis and the articular surfaces reveal valid and reproducible results. With the help of navigation, it is possible to achieve a higher degree of precision in total hip and knee implant placement, including a distinct reduction in variance as compared to conventional techniques. Similarly, application of navigation during a high tibial osteotomy or at the osteotomy of the distal radius also enables a more precise correction of the axis of the affected extremity, in addition to improved reproducibility. Despite these promising early results, large prospective clinical studies comparing conventional techniques versus computer assisted navigation are thus far only available for total knee arthroplasty. Whether navigated prosthesis placement can truly extend the longevity of an implant will require continued observation in the years to come. In addition, further prospective studies are required to determine the benefit of navigation in other orthopaedic procedures.

The influence of distance on registration in ISO-C-3D navigation: a source of error in ISO-C-3D navigation

Computer-assisted treatments have become increasingly common. Consequently, there is an increased desire for navigation methods with simplified workflow. Anatomic-based pair-point registration is often mentioned as a source of error. Alternatively, the use of preoperatively implanted markers for registration remains complex. The self-acting registration of Iso-C-3D at the moment of data acquisition can reduce essential errors. The aim of this study was to evaluate the effect of reference placement on accuracy, and to determine the maximum acceptable distance between the reference and a given isocentre. This study demonstrates the interdependence of the reference distance on the region of interest (ROI). The mean error of registration amounts to 0.04 mm (0.04-0.05 mm) up to a distance of 200 mm and beyond 0.25 mm (0.24-0.26) for distances beyond 200 mm. The accuracy was significantly lower (p<0.0001) with a distance more than 200 mm. For optimal accuracy when utilizing navigation for pelvic and long bone surgery, the reference base should not been placed at a distance more than 200 mm from the isocentre of interest.

Preliminary clinical experience using a newly developed minimal-invasive reference base in computer assisted foot surgery

In recent years, many new tools and techniques have been developed in computer assisted orthopaedic surgery primarily with an industry led effort in software innovation and development. Only a few research and clinical projects have focused on intraoperative difficulties. A common operative challenge in computer assisted orthopaedic surgery is the positioning of the reference base. Rigid fixation of a dynamic reference base is essential in navigated surgery of the extremities. The aim of this study was to develop a minimal-invasive screw which could be placed effectively and efficiently with rotational stability during computer assisted orthopaedic surgery. The minimal-invasive screw was initially evaluated in an artificial bone experiment. After successful results with the artificial bone experiment, it underwent testing in seven human cadaver thighs with ISO-C3D navigated drilling. Finally the screw was transferred into a clinical application during five foot surgeries. In 10 ISO-C3D navigated drillings, the lesions were targeted 100% of the drillings. A screw dislocation was not observed. In comparison to conventional one or two pin fixation systems, the newly designed small screw did not have any observed side effects such as artifacts. In addition, the screw generated less heterodyning than a conventional fixation system. The small screw design is an advantage in theatre. We believe the minimally-invasive screw allows the surgeon to use a tool that helps avoid common pitfalls from conventional fixation systems, and it may improve efficiency.

[Navigated reposition of transverse acetabulum fractures. A precision analysis]

Up to now navigated reduction control based on computed tomography (CT) image data could not be used commercially. With newly developed software, a transverse fracture of the acetabulum was reduced with navigation control in a laboratory test. The results were compared to visual and tactile control in a foam pelvis and specimen. Measurements were done with another magnet-based navigation system. The residual dislocation was measured with translation (mm) and rotation (degrees). Compared with visually controlled reduction, navigated reduction led to a residual dislocation of 0.7 mm and 0.9 degrees. Navigated reduction based on CT image data is also accurate for reduction of joint fractures under laboratory conditions. Further improvements of the software are planned for later in vivo use.

Navigierte Iso-C3D-basierte Anbohrung einer osteochondralen Läsion des Talus

Retrograde drilling of osteochondral lesions has obtained acceptable results in the initial stage. Intraoperatively not all lesions are accessible with the arthroscopic technique, despite being readily identifiable with modern imaging preoperatively. As an alternative, open surgical treatment is recommended to achieve good results. The use of computer-assisted navigated retrograde drilling of osteochondral lesions has been described with promising results as a new technique. Computed tomography (CT)- and fluoroscopy-based navigation systems in current use are limited in their flexibility. The drawbacks of fluoroscopy are lack of three-dimensional imaging intraoperatively. CT-based navigation still requires intraoperative cumbersome registration, extra preoperative planning, and imaging with further technical resources. In the current case report, we describe a patient with an osteochondral lesion of the posteromedial talus. In addition to the current method of arthroscopic evaluation and treatment, we also introduce an alternative technique of using Iso-C(3D)-based navigation-assisted retrograde drilling of the lesion. The advantages of this technique are an actual intraoperative three-dimensional imaging for the use of navigation without the need for anatomical registration and an immediate postoperative control of surgical treatment. The results of this case report demonstrate accurately navigated drilling with the described system. The accuracy was confirmed with immediate intraoperative Iso-C(3D) and postoperative CT scans. Our results indicate that the use of an Iso-C(3D) navigation system is a possible alternative to arthroscopic or open drilling for osteochondral lesions of the talus. To provide further evidence for the use of Iso-C (3D)-based drilling, current studies will start at our institution.

Computer-assisted fracture reduction of pelvic ring fractures: an in vitro study

A newly developed software module for computer-assisted surgery based on a commercially available navigation system allows simultaneous, independent registration of two fragments and real-time navigation of both fragments while reduction occurs. To evaluate the accuracy three fracture models were used: geometric foam blocks, a pelvic ring injury with disruption of the symphysis and the sacroiliac joint, and a pelvic ring fracture with symphysis disruption and a transforaminal sacral fracture. One examiner did visual and navigated reduction and in all experiments the end point was defined as anatomic reduction. Residual displacement was measured with a magnetic motion tracking device. The results revealed a significantly increased residual displacement with navigated reduction compared with visual control. The differences were low, averaging 1 mm for residual translation and 0.7 degrees for the residual rotation, respectively. Residual displacement was small in both set-ups and may not be clinically relevant. Additional development of the software prototype with integration of surface registration may lead to improved handling and facilitated multifragment tracking. Use in the clinical setting should be possible within a short time.

Frontal and sagittal balance analysis of late onset idiopathic scoliosis treated with third generation instrumentation

As scoliotic curve is a rotational deformity, derotation maneuvre was used as the corrective factor, but recent studies demonstrated spinal imbalance and decompensation problems in patients treated with this method. This study evaluates 217 late onset idiopathic scoliosis patients surgically treated with third generation instrumentation (Texas Scotish Rite Hospital System - TSRH) from September 1991 to November 1996 with a minimum 2 years follow up. Preoperative and postoperative Cobb angles in the frontal plane and thoracic kyphosis and lumbar lordosis angles in the sagittal plane are measured. The balance was analyzed clinically and radiologically by measurement of the lateral trunk shift (LT), shift of head (SH) and shift of stable vertebra (SS) in vertebral unit (VU). At final follow - up correction loss, infection and other complications were documented. Mean age of the patients was 14.8 +/- 2.3 and mean follow up period 55.8 +/- 29.5 months. When all the patients were included, preoperative mean Cobb angles of major curves in the frontal plane was 59.1 +/- 20.7 degrees. Major curves that were corrected by 34.8 +/- 20.5 % in the bending radiograms were achieved by 58.9 +/- 19.5 % correction postoperatively. At the last control, 7.3 degrees +/- 6.4 degrees of correction loss was recorded in major curves in the frontal plane. Also postoperative kyphosis angle and lumbar lordosis angles were 31.4 degrees +/- 11.6 degrees and 30.6 degrees +/- 10.9 degrees respectively. Postoperatively, a statistically significant correction was obtained in LT, SH and SS values. None of the patients had complete balance (SH: 0 VU, SS: 0 VU) preoperatively. Only 39.2 % of the patients had clinically balanced curves (0 VU < SH < 0.5 VU and 0 VU < SS < 0.5 VU). Postoperatively, 47.9 % of the patients were found to be completely balanced, while 43.8 % had a balanced curve. Overall 91.7 % of the patients had a trunk balance after surgical intervention. The remaining 8.3 % imbalanced curve rate raised up to 16.6 % at final follow up, but the loss of correction rates in S S and SH values were found to be insignificant. The postoperative "imbalance" problem was mostly seen in Type II and Type IV curves. However, at final follow up, the imbalance problem due to overcorrection which became evident especially by "shift of head" to opposite side was seen in all types of curves. It is established that high correction rates can be obtained in scoliotic curves with third - generation instrumentation. No undue effects were observed in the uninstrumented lumbar curves. Thoracic sagittal contours of the hypokyphotic patients were improved. Use of this instrumentation system causes minimal imbalance problems and with proper preoperative planning high correction rates can be achieved.

Isola spinal instrumentation system for idiopathic scoliosis

Since the definition of three-dimensional components of the scoliotic deformity, there have been important improvements in the surgical treatment of the problem. A derotation maneuver was proposed as a treatment option with CD instrumentation, but the reports of imbalance and decompensation with this system repopularized sublaminar wiring and translation as a corrective maneuver. Isola spinal instrumentation is one of the modern systems that utilizes vertebral translation instead of rod rotation. This study analyzes the results of 24 patients with idiopathic scoliosis who had been followed up for at least 2 years, and were surgically treated with titanium Isola Spinal Instrumentation in the Department of Orthopaedics and Traumatology, Ankara Social Security Hospital. Patients were grouped according to the King-Moe classification. Patients with type III, IV or V curves received only posterior instrumentation while this procedure followed anterior release and discectomy in the same session in patients with type I or II curves. A translation maneuver was utilized in the correction of scoliotic curves using the cantilever technique, either alone or supplemented by sublaminar wiring with Songer multifilament titanium cables. This study aimed to elucidate the effects of this technique in the frontal and sagittal plane curves and the trunk balance. The balance was analyzed clinically and radiologically by measurement of the lateral trunk shift (LT), shift of stable vertebra (SS), and shift of head (SH) in vertebral units (VU). The postoperative correction was significant in the frontal plane for all types of curves (p < 0.05). The postoperative correction was 80.9% +/- 9.5% in type III curves. Overall, the mean Cobb angle of the major curve value in the frontal plane was 66.9 degrees +/- 18.8 degrees, and it was corrected by 62.8% +/- 20.1%. The correction loss of Cobb angles in the frontal plane was 5.4 degrees +/- 5.5 degrees at the last follow-up visit. A normal physiologic thoracic contour (30 degrees - 50 degrees) was achieved in 83.3% of the patients and normal lumbar contour (40 degrees - 60 degrees) in 66.7% of the patients in the sagittal plane. The correction was found to be significant in all balance values (p < 0.05). The postoperative correction in LT values correlated with the correction of the Cobb angle values in the frontal plane. All patients had complete balance (SH: 0 VU and SS: 0 VU) or balanced curves (0 VU < SH, SS < 0.5 VU).Finally, the study concluded that the translation maneuver, especially when used with the cantilever technique, resulted in high correction rates in the frontal plane. Additionally, the technique was also successful in obtaining normal sagittal contours and correcting balance values.

The results of anterior radical debridement and anterior instrumentation in Pott's disease and comparison with other surgical techniques

Classic procedure in the treatment of vertebral tuberculosis is drainage of the abscess, curettage of the devitalized vertebra and application of antituberculous chemotherapy regimen. Posterior instrumentation results are encouraging in the prevention or treatment of late kyphosis; however, a second stage operation is needed. Recently, posterolateral or transpedicular drainage without anterior drainage or posterior instrumentation following anterior drainage in the same session is preferred to avoid kyphotic deformity. Seventy-six patients with spinal tuberculosis were operated in the 1st Department of Orthopaedics and Traumatology, Ankara Social Security Hospital, between January 1987 and January 1997. There were four children in our series. Average follow-up period was 36.1 +/- 14.5 months and the average age at the time of operation was 40.8 +/- 15.2 years. This study reports the surgical results of 45 patients with Pott's disease who had anterior radical debridement with anterior fusion and anterior instrumentation [14 patients with Z-plate and 31 patients with Cotrel-Dubousset-Hopf (CDH system)]. The results are compared with those of 8 patients who had posterolateral drainage and posterior fusion, 12 patients who had only anterior drainage and anterior strut grafting and, 11 patients who had posterior instrumentation following anterior radical debridement in the same session in terms of fusion rates, correction of kyphotic deformity, recurrence rate and clinical results. All patients had one year consecutive triple drug therapy. Preoperative 23.2 degrees +/- 12.5 degrees local kyphosis angle was lowered to 6.1 degrees +/- 6.9 degrees with a correction rate of 77.4 +/- 22.3%. When the other three groups which had been instrumented were compared, the correction rates in the local kyphosis angle values were not statistically different and the variation in loss of correction at the last follow-up was also statistically insignificant. The sagittal contour of the involved vertebra's region did not change in the uninstrumented group, while it did so in instrumented groups which had normal range values postoperatively. Overall, 27 patients had neurologic deficits preoperatively. Twenty of these (74.1%) had complete, and 5 (18.5%) had partial recovery with a combined 92.6% neurologic improvement. All the patients had a solid fusion mass at the last controls. Reactivation was not seen. Additionally, contrary to the common belief, anterior instrumentation which anterior autologous strut grafting following anterior radical debridement can be a good treatment option with low complication rate, high correction rate in acute local kyphosis, and high fusion rate.

The results of intraoperative autotransfusion in orthopaedic surgery

Perioperative hemorrhage associated with major orthopaedic surgery can become life threatening. Homologous bank blood transfusion can replace the volume of blood lost but it has serious disadvantages such as the transmission of viral agents, it has an insufficient platelet count, and transfusion reactions are possible. Hypotensive anesthesia, predeposited autologous blood transfusion and intraoperative autotransfusion are used to reduce these disadvantages. This study evaluates the results of 700 patients who underwent major orthopaedic intervention in our clinic between June 1991 and April 1998. Ninety-nine patients had hip surgery while 601 patients had spinal surgery. The autotransfusion unit saved an average of 858.9 +/- 136.8 cc of blood and an average of 1.9 +/- 1.2 units of saved blood was transfused. None of these patients needed homologous blood transfusion. One hundred patients who had spinal surgery during the same period were used as a control group. The control group required an average of 3.2 +/- 2.1 units of bank blood. Preoperative and postoperative hematocrit values revealed a statistically significant difference between the autotransfusion group and the homologous transfusion group (p < 0.05). The results of this study suggest that intraoperative autotransfusion prevents the decrease in hematocrit values while reducing the need for bank blood transfusion and hence avoiding the risk of transmission of viral infections.

Results of the AO spinal internal fixator in the surgical treatment of thoracolumbar burst fractures

The potential for clinical instability following thoracolumbar fractures has evoked a progressive increase in interest in the surgical treatment of unstable thoracolumbar fractures. From September 1988 to October 1991, 44 thoracolumbar burst fractures were treated surgically by the AO Spinal Internal Fixator at the Orthopaedics and Traumatology Clinics of Ankara Social Security Hospital. Mean follow-up period was 28.8 (range 12-48) months. Fourteen (31.8%) of the patients were female, and 30 (68.2%) were male. Postoperatively, the mean anterior vertebral height loss and spinal canal compromise were corrected by 36.5% and 39.9%, respectively. Also, postoperatively 15.9% of improvement was obtained in the mean kyphosis angle. The mean compression angle, which was 19.5 degrees preoperatively, was corrected by 12.3 degrees and came to an average of 7.1 degrees postoperatively. In light of these data, it is suggested that the AO Spinal Internal Fixator effectively restores three-dimensional alignment of the spine and provides a rigid fixation.

Cotrel-Dubousset instrumentation in the treatment of unstable thoracic and lumbar spine fractures

The use of computed tomography and developments in spinal biomechanics have led to a better understanding of vertebral fractures. The disappointing results achieved with conservative treatment have led to an increasing popularity of surgical treatment in the last 15 years. The results of 20 unstable thoracic or lumbar spine fractures treated surgically with Cotrel-Dubousset instrumentation at the First Clinic of Orthopaedics and Traumatology of the Ankara Social Security Hospital between December 1988 and June 1991 were evaluated in this study. The mean follow-up was 31.9 months. The mean sagittal index angle was 23.7 degrees +/- 6.8 degrees preoperatively and was corrected by 67.1 +/- 29.9%, and the thoracolumbar junction angle was brought within physiological limits in 65% of the cases. Postoperatively, the neurological status improved in 15% of the patients and remained unchanged in the rest. It was concluded that the Cotrel-Dubousset instrumentation established vertebral stability in unstable vertebral fractures by forming a rigid frame and restored physiological thoracic and lumbar postural contours due to its highly corrective effect in the sagittal plane.

Surgical management of infective endocarditis in children

Infective endocarditis occurs infrequently in the general pediatric population, occurring mostly in patients with congenital heart disease. This study reviews our surgical experience with infective endocarditis based on a policy of aggressive intervention, conservative operative debridement, and creative reconstruction options using pericardium and prosthetic heart valves. From 1982 to 1989, 16 patients, 3 weeks to 16 years of age, underwent 19 intracardiac operations for infective endocarditis therapy at Kosair Children's Hospital. Eight (42%) were for resection of vegetations alone; an additional 11 operations (58%) involved more extensive debridements requiring either valve replacement or valvuloplasty using pericardium for exclusion of an abscess cavity, closure of a fistula, or for valve repair. Operative mortality was 25% (4 patients) and related to preoperative disease severity. There was one late death. Offending organisms included Staphylococcus species (31%), Haemophilus influenzae (13%), pneumococcus (5%), gram-negative organisms (13%), and Candida (13%); no organism grew on culture in 25%. We conclude that aggressive surgical exploration in patients with infective endocarditis is indicated and often requires resection of vegetations alone. More extensive procedures should preserve as much valvular tissue as possible. Pericardium is useful for reconstruction after debridement.

The computed tomographic evaluation of patellofemoral joint in patellar fractures treated with open reduction and internal fixation

In this study, we examined 97 patella fractures in which open reduction and internal fixation had been performed at the 1st Orthopaedics and Trauma Clinic of Social Security Ankara Hospital between January 1983 and December 1988. After 24 to 96 months, on an average of 48.4 months follow-up period, the cases were evaluated clinically for knee function complaints and by CT and roentgenography for patellofemoral articulation. In 11 of the patients (11.5) there was patellar displacement, 2 of the patients had patellar tilt (2.1%) and in 14 patients (14.5%) there was malalignment in which 1 patient (1.1%) had both patellar tilt and displacement. This data was obtained by measuring femoral trochlear angle (FTA) and patellar tilt angle (PTA) by CT at various degrees of knee flexion. Thirty-three patients (34%) had slight and 19 patients (19.6%) had severe degenerative changes in the patellofemoral articulation. It is found that there is close relation between the variability of the pain complaints of the patients and the type of the fracture and the time of management and the postoperative rehabilitation.

Effects of postnatal maturation on postrest potentiation in isolated rabbit atria

Ultrastructural changes in cardiac sarcoplasmic reticulum (SR) have been reported during postnatal development of the mammalian heart, but the functional significance of these observations has not been well characterized. Calcium release from SR in intact myocardial preparations was determined by the contractile characteristics of postrest contractions. Isometric tension and the maximum rate of tension development of the first contraction following intervals of electromechanical quiescence (rest) were related to steady-state tension and maximum rate of tension development during contraction at constant frequency (1.0 Hz) in isolated left atrial strips from newborn (1-7 days), immature (14-21 days), and adult (more than 6 months) rabbits. The first postrest contraction was increased as a function of the rest interval rate of tension development, defined as postrest potentiation, in all three age groups and reached a maximum value at rest intervals of more than 20 s. Tension developed by the first contraction following a 60-s rest interval was potentiated less in newborn and immature atria than in adult atria at an extracellular calcium concentration ([Ca]e) of 2.5 mM, an age-related difference most marked in the immature. Ryanodine (5.0 X 10(-9) M), a putative blocker of calcium release from cardiac SR, abolished postrest potentiation providing evidence that calcium release from SR is the predominant determinant of the postrest contraction. Postrest tension in atria from the immature rabbit heart was significantly increased both in absolute terms and relative to steady-state tension following stabilization under conditions which increase intracellular [Ca] [( Ca]i), i.e. increasing [Ca]e, increasing tonicity, or decreasing extracellular sodium concentration ([Na]e).(ABSTRACT TRUNCATED AT 250 WORDS)