Timo Stuebig

Range of motion assessment of the shoulder and elbow joints using a motion sensing input device: a pilot study.

BACKGROUND Motion sensing input devices could provide a practical and low-cost alternative method for repeated range of motion measurements. This study aimed to assess the reliability, accuracy and time requirements of a motion sensing input device (Microsoft Kinect) for ROM measurements comparing it with goniometer based measurements and subjective estimation. MATERIAL AND METHODS Full ROM was measured in 14 shoulder and elbow joints using the different methods. The order was randomly selected and each movement was measured twice. The results were recorded in degrees and the time measured in seconds. RESULTS In general, there was a poor to moderate agreement between the Kinect system compared to the goniometer. There was a good agreement between the goniometer-based and the subjective technique. The Kinect-based technique showed excellent test-retest reliability. CONCLUSION The Kinect system showed good test-retest reliability, but lower accuracy compared to goniometer-based measurements. Improvements in patient positioning and measurement protocol standardization must be made before its implementation in clinical practice.

Radiological outcome and intraoperative evaluation of a computer-navigation system for femoral nailing: A retrospective cohort study

AIM Intraoperative determinations of femoral antetorsion and leg length during fixation of femoral shaft fractures present a challenge. In femoral shaft fracture fixations, a computer-navigation system has shown promise in determining antetorsion and leg length discrepancies. This retrospective cohort study aimed to determine whether the use of computer navigation during femoral nailing procedures reduced postoperative femoral malrotation and leg length discrepancy, as well as the number of revision cases. We also sought to determine whether radiation exposure time was reduced when computer navigation was used. MATERIALS AND METHODS Of 246 patients treated for femoral shaft fractures between 2004 and 2012, we selected those that received postoperative computed tomography for rotation and leg length control. We included 24 patients who received navigation-assisted treatments and 48 who received unassisted treatments, matched for age, sex, and fracture type. All patients were treated by femoral nailing. RESULTS The groups showed significant differences in the mean (standard deviation (SD) delay before surgery (navigation-assisted vs. unassisted groups: 8.5 ± 3.2 vs. 5.2 ± 5.8 days; P<0.05) and surgery times (163.7 ± 43.94 vs. 98.3 ± 28.13 min; P<0.001). The groups were significantly different in the mean (SD) radiation exposure time (4.43 ± 1.35 vs. 3.73 ± 1.5 min; P=0.042), and were not significantly different in the postoperative femoral antetorsion difference (8.83 ± 5.52° vs. 12.4 ± 9.2°; P=0.056), or in the postoperative length discrepancy (0.92 ± 0.75 vs. 0.95 ± 0.94 cm; P=0.453). Four (16.7%) navigation-assisted and 15 (31.25%) unassisted surgeries got revision for torsion and/or length corrections. CONCLUSION Our results showed that, compared to unassisted femoral surgery, the computer-navigation system did not improve postoperative results or reduce radiation exposure. In the future, improvements in handling and application could facilitate the workflow and may provide better postoperative results. Currently, computer navigation may provide advantages for complicated or sophisticated cases, such as complex three-dimensional deformity corrections. LEVEL OF EVIDENCE Level III.

Current Concepts for Patellar Dislocation

Context: Patellar dislocation usually occurs to the lateral side, leading to ruptures of the Medial Patellofemoral Ligament (MPFL) in about 90% of the cases. Even though several prognostic factors are identified for patellofemoral instability after patellar dislocation so far, the appropriate therapy remains a controversial issue. Evidence Acquisition: Authors searched the Medline library for studies on both surgical and conservative treatment for patellar dislocation and patellofemoral instability. Additionally, the reference list of each article was searched for additional studies. Results: A thorough analysis of the anatomical risk factors with a particular focus on patella alta, increased Tibial Tuberosity-Trochlear Groove (TT-TG) distance, trochlear dysplasia as well as torsional abnormalities should be performed early after the first dislocation to allow adequate patient counseling. Summarizing the results of all published randomized clinical trials and comparing surgical and conservative treatment after the first-time patellar dislocation until today indicated no significant evident difference for children, adolescents, and adults. Therefore, nonoperative treatment was indicated after a first-time patellar dislocation in the vast majority of patients. Conclusions: Surgical treatment for patellar dislocation is indicated primarily in case of relevant concomitant injuries such as osteochondral fractures, and secondarily for recurrent dislocations.

Injury patterns of seniors in traffic accidents: A technical and medical analysis

AIM To investigate the actual injury situation of seniors in traffic accidents and to evaluate the different injury patterns. METHODS Injury data, environmental circumstances and crash circumstances of accidents were collected shortly after the accident event at the scene. With these data, a technical and medical analysis was performed, including Injury Severity Score, Abbreviated Injury Scale and Maximum Abbreviated Injury Scale. The method of data collection is named the German In-Depth Accident Study and can be seen as representative. RESULTS A total of 4430 injured seniors in traffic accidents were evaluated. The incidence of sustaining severe injuries to extremities, head and maxillofacial region was significantly higher in the group of elderly people compared to a younger age (P < 0.05). The number of accident-related injuries was higher in the group of seniors compared to other groups. CONCLUSION Seniors are more likely to be involved in traffic injuries and to sustain serious to severe injuries compared to other groups.

Nail-medullary canal ratio affects mechanical axis deviation during femoral lengthening with an intramedullary distractor

INTRODUCTION Callus distraction of the femur using an intramedullary distractor has several advantages over the use of external fixators. However, difficulty in controlling the mechanical axis during lengthening may cause deformities and knee osteoarthritis. Purpose of the study is to answer the following questions: (1) is lengthening with an intramedullary device associated with a medial or lateral shift of the mechanical axis? (2) Which factors are associated with varisation/valgisation of the mechanical axis during lengthening? MATERIALS AND METHODS We analysed pre-treatment and post-treatment radiographs from 20 patients who underwent unilateral femoral-lengthening procedures using intramedullary distractors. Patients with acute correction of pre-existing deformities or combined ipsilateral femoral and tibial lengthening were excluded. Mechanical axis deviations, osteotomy level, and nail-medullary canal ratio were recorded. RESULTS Compared to the preoperative axis, the mechanical axis shifted medially in 7 patients (varisation group) and laterally in 13 patients (valgisation group). The groups did not significantly differ regarding preoperative leg length discrepancy (LLD), mechanical axis alignment, LLD-cause and implants used. The nail-medullary canal ratio significantly differed between groups (p<0.001), being <85% in the varisation group and >85% in the valgisation group. The distance between the lesser trochanter and the osteotomy site was significantly longer in the valgisation group (58.9±16.3mm, middle third of the femur) compared to the varisation group (40.6±11.4mm, proximal third of the femur; p=0.02). CONCLUSION The nail-medullary canal ratio should be considered during preoperative planning. To avoid a varisation effect-for example, in cases with pre-existing varus alignment-it would be advisable to perform an osteotomy at the middle third of the femur with implantation of a nail that fully covers the medullary canal at the osteotomy site. LEVEL OF EVIDENCE Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Robotic distal locking of intramedullary nailing: Technical description and cadaveric testing

Interlocked intramedullary nailing is the treatment of choice for femoral shaft fractures. However, distal locking is a technically challenging part of the procedure that can result in distal femoral malrotation and high radiation exposure. We have tested a robotic procedure for robotic distal locking based on the computation of a drilling trajectory on two calibrated fluoroscopic images. Twenty distal holes were attempted in ten cadaveric femur specimens. Successful screw hole drilling was achieved at the first attempt in each of the ten specimens (20 drill holes in total). No failures were recorded. The average total number of images needed was 6.5 +/− 3.6. The average computation time was 16.5+/− 16.0 seconds. Robotic distal locking was feasible in this test and can be integrated into a fully robotic intramedullary nailing procedure.

Computer navigation for total knee arthroplasty achieves better postoperative alignment compared to conventional and patient-specific instrumentation in a low-volume setting

BACKGROUND Procedure volume is an important determinant of total knee arthroplasty (TKA) outcomes. We aimed to determine whether computer navigation or patient-specific instrumentation (PSI) would improve postoperative alignment in a low-volume setting. HYPOTHESIS PSI for TKA achieves better limb and implant alignment compared to conventional TKA and to computer navigated TKA. MATERIALS AND METHODS This is a retrospective cohort study of 385 primary TKAs (Women=59%. Mean age=67years. Mean BMI=30.1kg/m2), which were performed using conventional instrumentation (n=117; 30%), computer navigation (n=209; 54%), or patient-specific instrumentation (n=59; 15%) in a low-volume center (<50 TKAs/year). The risk of postoperative leg and implant mechanical alignment outliers in the coronal plane (>3° from neutral), average alignment and operation time were assessed. RESULTS The risk of postoperative mechanical alignment outliers (>3°) was reduced by 89% in the navigated group (4% outliers) compared to the conventional group (35%) (RR=0.11; p<0.0001). No significant improvement was observed in the PSI group (27%) (RR=0.91; p=0.772). The risk of postoperative femoral component coronal alignment outliers was reduced by 63% in the navigated group (11%) compared to the conventional group (31%) (RR=0.37; p=0.018). No significant reduction in outliers was observed in the PSI group (32%) (RR=1.08; p=0.816). There was a reduction in the risk of tibial component coronal malalignment of 66% in the navigated group (5%) compared to the conventional group (13%) (RR=0.33; p=0.070). There was a two-fold increase in the risk of tibial component alignment outliers in the PSI group (29%) (RR=1.94; p=0.110). DISCUSSION Computer navigation improved postoperative alignment in TKA. No evidence of improved alignment was seen with patient-specific instrumentation. The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data. TYPE OF STUDY Retrospective cohort study. Level IV.

Effect of Femoral Antetorsion on Tibiofemoral Translation and Rotation in the Anterior Cruciate Ligament Deficient Knee

We aimed to investigate how increased or decreased femoral antetorsion would affect the biomechanics of the knee in an anterior cruciate ligament (ACL)-deficient cadaveric model. We hypothesized that external or internal rotation of the distal femur, achieved through a femoral osteotomy, would affect the magnitude of tibiofemoral translation and rotation. Navigated measurements of tibiofemoral translation and rotation during the anterior drawer, Lachman, and pivot shift tests were performed on six whole-body cadaveric specimens in each of the following four conditions: native, ACL-deficient knee, ACL-deficient knee and 20-degree internal distal femur rotation, and ACL-deficient knee and 20-degree external distal femur rotation. Increased femoral antetorsion significantly reduced anterior tibial translation in the ACL-deficient knee during the anterior drawer, Lachman, and pivot shift tests (p < 0.05). Conversely, decreasing femoral antetorsion resulted in an increase in anterior tibial translation in the anterior drawer (nonsignificant), Lachman (p < 0.05), and pivot shift (p < 0.05) tests. Internally rotating the distal femur significantly reduced the magnitude of tibial rotation during the pivot shift test in the ACL-deficient knee (p < 0.05), whereas external rotation of the distal femur significantly increased tibial rotation (p < 0.05). The magnitude of femoral antetorsion affects tibiofemoral translation in an ACL-deficient cadaveric mode. Internally rotating the distal femur 20 degrees reduced the magnitude of tibial translation and rotation similar to that of the native knee, whereas externally rotating the distal femur aggravated translational and rotational instability.

Comparison of algorithms for automated femur fracture reduction

We designed an experiment to determine the comparative effectiveness of computer algorithms for performing automated long bone fracture reduction.

Improving the human–robot interface for telemanipulated robotic long bone fracture reduction: Joystick device vs. haptic manipulator

Intramedullary nailing is the treatment of choice for femoral shaft fractures. However, there are several problems associated with the technique, e.g. high radiation exposure and rotational malalignment. Experimental robotic assistance has been introduced to improve the quality of the reduction and to reduce the incidence of rotational malalignment. In the current study, we compare two devices for control of the fracture fragments during telemanipulated reduction.