Jan Bredow

Robot‐assisted fracture reduction using three‐dimensional intraoperative fracture visualization: An experimental study on human cadaver femora

Closed fracture reduction can be a challenging task. Robot‐assisted reduction of the femur is a newly developed technique that could minimize potential complications and pitfalls associated with fracture reduction and fixation. We conducted an experimental study using 11 human cadaver femora with intact soft tissues. We compared robot‐assisted fracture reduction using 3D visualization with manual reduction, using 2D fluoroscopy. The main outcome measure was the accuracy of reduction. The manual reductions were done by an experienced orthopedic trauma surgeon, whereas the robot‐assisted reductions were done by surgeons of different experience. The robot‐assisted group showed significantly less postreduction malalignment (p < 0.05) for internal/external rotation (2.9° vs. 8.4°) and for varus/valgus alignment (1.1° vs. 2.5°). However, the reduction time was significantly (p < 0.01) longer (6:14 min vs. 2:16 min). The higher precision associated with robot‐assisted fracture reduction makes this technique attractive and further research and development worthwhile. In particular, less experienced surgeons may benefit from this new technique.

Robot Assisted Fracture Reduction

Reduction in femoral shaft fractures may be difficult to achieve with minimal invasive techniques. Malalignment and high intraoperative radiation exposures often results. Our hypothesis is that robot assisted fracture reduction may improve the precision of reduction while reducing the amount of radiation exposure. We present a telemanipulator system for robot assisted reduction of femoral shaft fractures. The telemanipulated reduction is performed with a 2 dof input device with haptical feedback based on intraoperatively acquired 3D imaging data. We performed a test series to measure achievable reduction accuracies on artificially broken human femur bones without soft tissues. Furthermore, we performed first tests for the reduction on complete human legs in 3D. It could be shown, that telemanipulated reduction of such fractures in 3D is yielding very good accuracies in an intuitive and efficient way. Robot assisted fracture reduction can improve the reduction accuracy and reduce the X-ray irradiation exposure to the patient and the OR staff.

A short-stem hip implant with metaphyseal anchorage in patients with developmental dysplasia of the hip

BACKGROUND Short-stem implants are routinely used for total hip arthroplasty in younger patients that are more likely to have secondary osteoarthritis than older patients. OBJECTIVE To investigate the applicability of short-stem hip implants for secondary osteoarthritis due to developmental dysplasia of the hip. METHODS This study analyzed the clinical and radiological results of patients with developmental dysplasia of the hip (DDH, 58 hips) and compared them to those of patients with primary osteoarthritis (POA, 59 hips) treated with the metaphyseal total hip arthroplasty (Metha®) short stem with metaphyseal fixation. RESULTS The mean clinical and radiological follow-up periods were 2.9 ± 1.1 years and 3.8 ± 1.9 years, respectively. The mean Harris Hip Score (HHS) significantly increased in both groups over this period (p< 0.0001). The caput-collum-diaphysis (CCD) angle was significantly lower in the POA group prior to surgery and significantly increased in the POA and and decreased in DDH groups, respectively. The preoperative femoral offset was lower in the DDH group and increased significantly after surgery. CONCLUSIONS The Metha® short stem in patients with DDH allows good reconstruction of joint biomechanics with a good clinical outcome.

Effect of prolonged-released oxycodone/naloxone in postoperative pain management after total knee replacement: a nonrandomized prospective trial

PURPOSE The purpose of this study was to examine the effect of postoperative prolonged release oxycodone/naloxone (OXN) in comparison to other opioids (control group) on the early postoperative rehabilitation outcome after total knee replacement. METHODS In a prospective, noninterventional, nonrandomized clinical trial, 80 patients were assigned to either the OXN group or a control group. Postoperative outcome and pain level at days 3, 6, 21, 35, and 6months were evaluated using the Bowel Function Index, Brief Pain Inventory Short Form questionnaire, the Hospital for Special Surgery score, modified Larson score, and the ability to attend physiotherapy. Medications were recorded and safety analysis was done. Both groups were compared using an analysis of covariance. RESULTS There were no significant differences between both groups regarding pain levels. OXN group patients reported better bowel function (median values of 0.0 for the OXN group and 20.0 for the control group). No effect of treatment group (P=.19) and no treatment-by-visit interaction on Hospital for Special Surgery final score (P=.67) could be detected, but Larson function score in the early postoperative phase was significantly better in the OXN group (P=.018). The proportion of OXN group patients who were able to attend without any restriction was 58.1%. The proportions of patients in the OXN group and control group who experienced mild or moderate adverse drug reactions were 23.3% and 37.8%, respectively. There were no serious adverse drug reactions. CONCLUSION In conclusion, OXN provides an effective analgesia and offers several benefits such as higher ability to participate in physiotherapy and better functional results. Incidence and severity of constipation can be reduced by using prolonged-released OXN as compared with other opioids.

Dual-position calibration markers for total hip arthroplasty: theoretical comparison to fixed calibration and single marker method

PurposeDigital templating is considered a standard for total hip arthroplasty. Different means for the necessary calibration of radiographs are known. While single marker calibration with radiopaque spheres is the most common, it is associated with possible significant deviations from the true magnification of the hip. Notably, fixed magnification factors showed better results. Therefore, a dual-position calibration marker method was simulated and compared to the established methods.MethodsFirst, an empirical fixed magnification factor was identified and applied to a series of radiographs. Second, three magnification factors were generated based on sagittal patient data of 398 CT scans. These methods were compared to the fixed factor.ResultsThe fixed factor was 122.6%. In the clinical application, the error of the fixed factor was 2.5% while the error of the single marker was 5.2%. In the CT cohort, the mean reference factor was 120.5% in females and 120.3% in males. The reference factor was compared to sex-specific means, sex-specific linear functions, and sex-specific cubic functions. The best results were found for the linear regression model with a mean difference of 0.8% from the reference value. No proportional bias was found (p = 0.623).ConclusionThe simulation of the dual-position marker method using the linear regression model showed promising results, superior to all other methods. In future studies, its clinical application should be tested.

Lebensqualität und funktionelles Ergebnis nach mikrochirurgischer Dekompression bei lumbaler Spinalkanalstenose – eine Registerstudie

Introduction Because of recent increases in life expectancy, lumbar spinal stenosis (LSS) has become one of the most common degenerative changes in the spine. In patients not responding to conservative therapy, microsurgical decompression is the gold standard of operative treatment for degenerative LSS. The goal of the current study is to evaluate quality of life after microsurgical decompression for LSS, using data from the DWG Register (previously Spine Tango). Methods 36 patients were included in this single-center, prospective, observational study from January 2013 to June 2014. Data were collected from the Spine Tango or DWG Register. The core outcome measure index (COMI), Oswestry Disability Index (ODI), and the quality of life questionnaire EuroQoL-5D were used. Data were collected prior to surgery as well as six weeks, six months, and twelve months after the operation. Results The patient cohort comprised 13 females and 23 males (36.1 and 63.9 %). Complete 12-month follow-up data on 21 patients were available for analysis. Compared to preoperative measures, the COMI score increased 8.1 ± 1.5 over the entire follow up, with 4.5 ± 3.1 at 6 weeks (p < 0.001), 4.8 ± 3.1 at 6 months, and 3.8 ± 3.2 at 12 months. ODI scores, measuring spinal function impairment, were significantly better than preoperative values overall (47.5 ± 17.3) and after 6 weeks (29.1 ± 22.4; p < 0.005), 6 months (30.0 ± 19.3), and 12 months (23.8 ± 18.2). Quality of life measures improved in a similar manner (preoperative: 0.36 ± 0.38; 6 weeks: 0.57 ± 0.34 (p < 0.019); 6 months: 0.62 ± 0.28; 12 months: 0.67 ± 0.31). Conclusion Our study shows that LSS patients without previous surgery and neurologic deficits can expect significant pain relief and improved quality of life already six weeks after undergoing stabilizing decompression. There was an increase in positive postoperative effects over 12 months. The DWG Register provides a standardized and validated means to compare non-operative and operative treatments of the spine over the long term.

Einfluss osteoligamentärer Verletzungen auf die Stabilität des atlantoaxialen Komplexes

Background The odontoid process and the transverse ligament are the most important structures stabilising the atlantoaxial complex. It has not been fully elucidated how injuries of these structures contribute towards instability and a potential narrowing of the spinal canal. Therefore, our investigation aimed to perform a biomechanical analysis of spinal width and dislocation of the odontoid process depending on injuries of the aforementioned structures. Methods In 10 fresh human cadaveric specimens, physiologic flexion and extension were simulated under fluoroscopy in intact specimens and after application of an odontoid process fracture and transverse ligament rupture in a crossover design. The width of the spinal canal and the dislocation of fragments were measured. Results In the intact condition, values of 19.8/19.5/19.8 mm (neutral/flexion/extension) were observed regarding spinal width. After an isolated fracture, values were 18.5/18.9/17.9 mm. With additional ligamentous injury, values changed to 20.3/19.4/22.6 mm. In the second group, values after initial ligament injury were 18.6/16.2/17.3 mm and 16.6/14.1/18.7 mm after fracture. Dislocation of fragments after an isolated fracture averaged 2.2/2.5/2.5 mm; an additional ligamentous injury led to 2.6/2.2/2.2 mm. In the second group, where a ligamentous injury preceded the fracture, a dislocation of 1.5/1.9/3.5 mm was detected after the fracture. Conclusion Neurological disorders have been observed starting at a spinal canal constriction of 2.0 mm. Our results demonstrate that a relevant constriction of the spinal canal may be due to isolated or combined injuries of the bone and the transverse ligament. Furthermore, our results show the importance of posttraumatic immobilisation of the spine with a view to the role of the transverse ligament for stabilisation of the atlantoaxial complex.

Non-operative treatment of lumbar spinal stenosis

BACKGROUND AND OBJECTIVE Non-operative treatment is widely accepted for early stages of lumbar spinal stenosis. In general, a trial of conservative treatment is recommended prior to surgery. However, there is an ongoing debate regarding benefits from non-operative treatment and their duration. METHODS Thirty-eight patients were included in this prospective study. All patients received repeated epidural injections and facet joint injections as well as physiotherapy during a one week hospitalization. Patient characteristics, VAS scores, COMI and ODI scores and SF-36 were assessed prior to and immediately after treatment as well as after six, twelve, and 26 weeks. For six weeks after treatment, patients were asked to record a pain diary. RESULTS Back and leg pain scores improved significantly on VAS up to three months follow-up. COMI score improved significantly over the entire follow-up. Regarding quality of life, mental sub-scores showed no improvement. Physical component summary scores improved for the first three months. CONCLUSIONS Non-operative treatment offers pain relief and improves physical function for three months. COMI scores improve up to six months follow-up. Spine Tango registry offers standardized instruments for outcome evaluation of non-operative treatment.

The Influence of Hip Rotation on Femoral Offset Following Short Stem Total Hip Arthroplasty.

Short stem total hip arthroplasty (THA) is thought to be an advantageous surgical option for young patients. Femoral offset has been identified as an important factor for clinical outcome of THA. However, little is known on functional implications of femoral offset after short stem THA. Importantly, hip rotation influences the projected femoral offset and may lead to significant underestimation. Therefore, a novel method to identify and account for hip rotation was applied to a prospectively enrolled series of 37 patients (48 radiographs) undergoing short stem THA. Repeated measurements were performed and intraobserver and interobserver reliability was assessed and femoral offset was corrected for rotation. Based on this study, rotation-correction of femoral offset is of highest relevance for the correct interpretation in future studies.

Correction to: Does increased femoral antetorsion predispose to cartilage lesions of the patellofemoral joint?

Unfortunately, the following reference was not included in the original publication of the article.