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1.  Objective Assessment of shoulder mobility with a new 3D gyroscope - a validation study 
Background
Assessment of shoulder mobility is essential for clinical follow-up of shoulder treatment. Only a few high sophisticated instruments for objective measurements of shoulder mobility are available. The interobserver dependency of conventional goniometer measurements is high. In the 1990s an isokinetic measuring system of BIODEX Inc. was introduced, which is a very complex but valid instrument. Since 2008 a new user-friendly system called DynaPort MiniMod TriGyro ShoulderTest-System (DP) is available. Aim of this study is the validation of this measuring instrument using the BIODEX-System.
Methods
The BIODEX is a computerized robotic dynamometer used for isokinetic testing and training of athletes. Because of its size the system needs to be installed in a separated room. The DP is a small, light-weighted three-dimensional gyroscope that is fixed on the distal upper patient arm, recording abduction, flexion and rotation. For direct comparison we fixed the DP on the lever arm of the BIODEX. The accuracy of measurement was determined at different positions, angles and distances from the centre of rotation (COR) as well as different velocities in a radius between 0° - 180° in steps of 20°. All measurements were repeated 10 times. As satisfactory accuracy a difference between both systems below 5° was defined. The statistical analysis was performed with a linear regression model.
Results
The evaluation shows very high accuracy of measurements. The maximum average deviation is below 2.1°. For a small range of motion the DP is slightly underestimating comparing the BIODEX, whereas for higher angles increasing positive differences are observed.
The distance to the COR as well as the position of the DP on the lever arm have no significant influence. Concerning different motion speeds significant but not relevant influence is detected. Unfortunately device related effects are observed, leading to differences between repeated measurements with any two different devices up to 8° at maximal range of motion (180°).
Conclusions
In summary the results shows high correlation and good reproducibility of measurements. All deviations are inside the tolerance interval of 5°, if one device is used. An unlikely systematic device effect is detected. These laboratory trials are promising for the validation of this system in humans. The challenge for both systems will be the changing of the COR in the shoulder joint at elevations higher than 90°.
doi:10.1186/1471-2474-12-168
PMCID: PMC3151225  PMID: 21777447
2.  Closing-wedge high tibial osteotomy: survival and risk factor analysis at long-term follow up 
Background
Closing-wedge high tibial osteotomy (HTO) is successful for the treatment of medial osteoarthritis with varus malalignment. Preoperative risk factors for HTO failure are still controversial. The aim of this study was to elucidate the outcome and assess the influence of risk factors on long term HTO survival.
Methods
199 patients were retrospectively studied with a mean follow-up period of 9.6 years after HTO. HTO failure was defined as the need for conversion to TKA. Survival was analyzed with the Kaplan-Meier method. Knee function was evaluated by the Hospital for Special Surgery (HSS) score. HTO-associated complications were also assessed. Univariate, multivariate, and logistic regression analysis were performed to evaluate the influence of age, gender, BMI, preoperative Kellgren-Lawrence osteoarthritis grade, and varus angle on HTO failure.
Results
39 complications were recorded. Thus far, 36 HTOs were converted to TKA. The survival of HTO was 84% after 9.6 years. Knee function was considered excellent or good in 64% of patients. A significant preoperative risk factor for HTO failure was osteoarthritis, Kellgren-Lawrence grade >2.
Conclusion
HTO provides good clinical results in long-term follow-up. Preoperative osteoarthritis Kellgren-Lawrence grade >2 is a significant predictive risk factor for HTO failure. Results of HTO may be improved by careful patient selection. Complications associated with HTO should not be underestimated.
doi:10.1186/1471-2474-12-46
PMCID: PMC3046001  PMID: 21320313
3.  Navigation of total knee arthroplasty: rotation of components and clinical results in a prospectively randomized study 
Background
Navigation was introduced into total knee arthroplasty (TKA) to improve accuracy of component position, function and survival of implants. This study was designed to assess the outcome of navigated TKA in comparison with conventional implantation with the focus on rotational component position and clinical mid-term results.
Methods
In a prospectively randomized single-blinded approach, 90 patients with primary gonarthrosis were assigned to three different groups. Thirty patients each were assigned to NexGen LPS without and with navigation (groups 1 and 2), and 30 patients to navigation with the Stryker Scorpio PS (group 3). The navigation system used was the imageless Stryker KneeTrac, version 1.0. Clinical outcome was assessed by a blinded observer applying the Knee Society Score (KSS) and a visual analogue scale (VAS) for pain. CT scans and radiographs were conducted prior to and 12 weeks after index surgery.
Results
Seventy-nine patients were available for clinical evaluation at 3 ± 0.4 years follow-up. Four implants had to be revised for early loosening or infection (4.4%). Four patients had died and three patients were not able to follow the invitation for clinical assessment. Functional results in the KSS were significantly lower after navigated TKA. Operation time and incisions with navigation were significantly longer. Significantly less radiological outliers with navigation were found for coronal alignment of the femur, only.
Conclusion
In this series, no beneficial effect for navigation in TKA could be shown assessing clinical data, as functional results in the presented series seemed to be lower after first generation navigated TKA. The clinical mid- to long-term value of navigation remains to be evaluated in larger patient series or meta-analyses at longer follow-up.
Trial registration number
DRKS 00000430
doi:10.1186/1471-2474-12-16
PMCID: PMC3025928  PMID: 21235810
4.  An ex vivo continuous passive motion model in a porcine knee for assessing primary stability of cell-free collagen gel plugs 
Background
Primary stability of cartilage repair constructs is of the utmost importance in the clinical setting but few continuous passive motion (CPM) models are available. Our study aimed to establish a novel ex vivo CPM animal model and to evaluate the required motion cycles for testing the mechanical properties of a new cell-free collagen type I gel plug (CaReS®-1S).
Methods
A novel ex vivo CPM device was developed. Full-thickness cartilage defects (11 mm diameter by 6 mm deep) were created on the medial femoral condyle of porcine knee specimens. CaReS®-1S was implanted in 16 animals and each knee underwent continuous passive motion. After 0, 2000, 4000, 6000, and 8000 motions, standardized digital pictures of the grafts were taken, focusing on the worn surfaces. The percentage of worn surface on the total CaReS®-1S surface was evaluated with image processing software.
Results
Significant differences in the worn surface were recorded between 0 and 2000 motion cycles (p < 0.0001). After 2000 motion cycles, there was no significant difference. No total delamination of CaReS®-1S with an empty defect site was recorded.
Conclusion
The ex vivo CPM animal model is appropriate in investigating CaReS®-1S durability under continuous passive motion. 2000 motion cycles appear adequate to assess the primary stability of type I collagen gels used to repair focal chondral defects.
doi:10.1186/1471-2474-11-283
PMCID: PMC3019221  PMID: 21159196
5.  TKA following high tibial osteotomy versus primary TKA - a matched pair analysis 
Background
High tibial osteotomy (HTO) is a well established technique for the treatment of medial osteoarthritis of the knee with varus malalignment. Results of total knee arthroplasty (TKA) after previous HTO are still discussed controversially. The aim of this study was to elucidate the clinical and radiological results as well as perioperative data of prior HTO on TKA.
Methods
Forty-one TKA after HTO were compared to 41 primary TKA at minimum of six years follow-up. Patients were matched according to age, gender, follow-up, etiology, and prosthetic design. Surgical data and complications were evaluated. Clinical outcome was assessed using a number of clinical scores and the visual analogue scale (VAS) for pain. X-rays were evaluated by the method of the American Knee Society. The patellar position was measured by the Insall-Salvati ratio.
Results
There was no significant difference in mean operation time (p = 0.47) and complication rate (p = 0.08). The Knee Score of the KSS (p = 0.0007) and the ROM (p = 0.006 for extension and p = 0.004 for flexion, respectively) were significantly better in the control group. Mid-term results of the VAS, WOMAC, Lequesne, UCLA, Feller's Patellar Score and SF-36 showed no significant difference. Femoral and tibial component alignment were similar in both groups. One tibial component showed suspect radiolucencies in the HTO group. The Insall-Salvati ratio showed three patients with patella alta and one patient with patella baja in the HTO group. At latest follow-up all implants were still in place.
Conclusions
Evaluating the clinical and radiological outcome, significant differences were only detected for range of motion and the Knee Score of the KSS. The present study suggests that the results of TKA with and without prior HTO are mainly identical. Although patients with a previous HTO had more complications, no statistically significant differences were noted with this group size.
doi:10.1186/1471-2474-11-207
PMCID: PMC2944221  PMID: 20840744
6.  Co-occurrence of outlet impingement syndrome of the shoulder and restricted range of motion in the thoracic spine - a prospective study with ultrasound-based motion analysis 
Background
Shoulder complaints, and especially the outlet-impingement syndrome, are a common condition. Among other things, poor posture has been discussed as a cause. A correlation between impingement syndrome and restricted mobility of the thoracic spine (T) has been described earlier, but there has been no motion analysis of the thoracic spine to show these correlations. In the present prospective study, we intended to find out whether there is a significant difference in the thoracic sagittal range of motion (ROM) between patients with a shoulder outlet impingement syndrome and a group of patients who had no shoulder pathology. Secondly, we wanted to clarify whether Ott's sign correlates with ultrasound topometric measurements.
Methods
Two sex- and age-matched groups (2 × n = 39) underwent a clinical and an ultrasound topometric examination. The postures examined were sitting up straight, sitting in maximal flexion and sitting in maximal extension. The disabilities of the arm, shoulder and hand (DASH) score (obtained by means of a self-assessment questionnaire) and the Constant score were calculated. Lengthening and shortening of the dorsal projections of the spine in functional positions was measured by tape with Ott's sign.
Results
On examination of the thoracic kyphosis in the erect seated posture there were no significant differences between the two groups (p = 0.66). With ultrasound topometric measurement it was possible to show a significantly restricted segmental mobility of the thoracic spine in the study group compared with the control group (p = 0.01). An in-depth look at the mobility of the subsegments T1-4, T5-8 and T9-12 revealed that differences between the groups in the mobility in the lower two sections of the thoracic spine were significant (T5-8: p = 0.03; T9-12: p = 0.02). The study group had an average Constant score of 35.1 points and the control group, 85.5 (p < 0.001). On the DASH score the patient group reached 34.2 points and the control group, 1.4 (p < 0.001). The results of Ott's sign differed significantly between the two collectives (p = 0.0018), but showed a weak correlation with the ultrasound topometric measurements (study group flexion/extension: r = 0.36/0.43, control group flexion/extension: r = 0.29/0.26).
Conclusion
The mobility of the thoracic spine should receive more attention in the diagnosis and therapy of patients with shoulder outlet impingement syndrome.
doi:10.1186/1471-2474-11-135
PMCID: PMC2903509  PMID: 20587014
7.  Results of the cementless Plasmacup in revision total hip arthroplasty: a retrospective study of 72 cases with an average follow-up of eight years 
Background
There are multiple revision implant systems currently available for socket revision in revision total hip arthroplasty. Up until now, not all of these systems have been followed up with regards to their long-term use as a revision implantation.
For the first time, this study presents the hemispherical porous-coated socket Plasmacup SC, produced by Aesculap, Tuttlingen, Germany, and the clinical and radiological mid-term results of this revision cup implant.
Methods
Over a period of ten years the Plasmacup SC press-fit-cup was used as a revision implant in 72 consecutive aseptic cases which were included in this retrospective study. The mean follow-up period was 8 years. Bone graft transplantation was performed in 32% of all cases. In 90%, the cup was fixed with additional screws. The follow-up radiographs were analysed with regards to cup migration, osteointegration and osteolysis in the DeLee zones using a computer aided program taking the teardrop figure as a main point of reference. For clinical evaluation the Harris-Hip-Score and the WOMAC-Score were utilized.
Results
At the follow up examination, the mean Harris-Hip-Score was 83.5 points and the mean WOMAC-Score 34.7 points. 93% of all patients were satisfied with the result of the operation. No aseptic cup loosening could be observed and only one cup had to be removed due to infection. No significant longitudinal or transversal cup migration could be observed.
Conclusion
Aesculap's Plasmacup SC is suitable as a cementless cup revision implant. There is stable cup osteointegration, post press-fit implantation, even in the case of major acetabular bone defects.
doi:10.1186/1471-2474-11-101
PMCID: PMC2887774  PMID: 20507578

Results 1-7 (7)